United States
Environmental Protection
Agency
Industrial Environmental Research
Laboratory
Cincinnati OH 45268
EPA-600/2-79-207
December 1979
Research and Development
&EPA
Volatile Component
Recovery from
Sulfite Evaporator
Condensate
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RESEARCH REPORTING SERIES
Research reports of the Office of Research and Development, U.S. Environmental
Protection Agency, have been grouped into nine series. These nine broad cate-
gories were established to facilitate further development and application of en-
vironmental technology. Elimination of traditional grouping was consciously
planned to foster technology transfer and a maximum interface in related fields.
The nine series are:
1. Environmental Health Effects Research
2. Environmental Protection Technology
3. Ecological Research
4. Environmental Monitoring
5. Socioeconomic Environmental Studies
6. Scientific and Technical Assessment Reports (STAR)
7. Interagency Energy-Environment Research and Development
8. "Special" Reports
9. Miscellaneous Reports
This report has been assigned to the ENVIRONMENTAL PROTECTION TECH-
NOLOGY series. This series describes research performed to develop and dem-
onstrate instrumentation, equipment, and methodology to repair or prevent en-
vironmental degradation from point and non-point sources of pollution. This work
provides the new or improved technology required for the control and treatment
of pollution sources to meet environmental quality standards.
This document is available to the public through the National Technical Informa-
tion Service, Springfield, Virginia 22161.
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EPA-600/2-79-207
December 1979
VOLATILE COMPONENT RECOVERY
FROM
SULFITE EVAPORATOR CONDENSATE
by
Walter A. Sherman
William A. Dryer
John D. Michna
Flambeau Paper Co.
Park Falls, WI 54552
Grant No. S803302-01-0
Project Officers
Donald L. Wilson and Ralph H. Scott
Industrial Pollution Control Division
Industrial Environmental Research Laboratory
Cincinnati, Ohio 45268
INDUSTRIAL ENVIRONMENTAL RESEARCH LABORATORY
OFFICE OF RESEARCH AND DEVELOPMENT
U.S. ENVIRONMENTAL PROTECTION AGENCY
CINCINNATI, OHIO 45268
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DISCLAIMER
This report has been reviewed by the Industrial Environ-
mental Research Laboratory, Cincinnati, OH, U.S. Environmental
Protection Agency, and approved for publication. Approval
does not signify that the contents necessarily reflect the views
and policies of the U.S. Environmental Protection Agency, nor
does mention of trade names or commercial products constitute
endorsement or recommendation for use.
ii
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FOREWORD
When energy and material resources are extracted, processed,
converted and used, the related pollutional impacts on our envi-
ronment and even on our health often require that new and in-
creasingly more efficient pollution control methods be used. The
Industrial Environmental Research Laboratory - Cincinnati (IERL-
CI) assists in developing and demonstrating new and improved
methodologies that will meet these needs both efficiently and
economically.
This report "VOLATILE COMPONENT RECOVERY FROM SULFITE EVAPO-
RATOR CONDENSATE" is intended to show how volatile chemicals can
be stripped from or adsorbed from Sulfite Evaporator Condensate
and be purified so that they can be sold as raw materials for
other processes. This process should allow a company to remove
certain chemicals from its waste stream and reduce the BOD load
to its effluent treatment plant. The sale of the recovered
chemicals should be able to pay for the operating cost of the
plant. For further information, please contact the Food and Wood
Products Branch of the Industrial Environmental Research Labora-
tory, Cincinnati, Ohio.
David G. Stephan
Director
Industrial Environmental Research Laboratory
Cincinnati
111
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ABSTRACT
This study is on the operation of a demonstration unit to
remove sulfur dioxide, methanol, furfural and acetic acid from
evaporator condensate produced from a calcium base acid sulfite
cook. This unit consisted of a steam stripper, vent tank for
SC>2 recovery, activated carbon adsorption columns ,and fractional
distillation columns.
The steam stripper and the fractional distillation units
used to purify the stripped material operated very successfully
with little maintenance. During an extended test run, this
stripping process removed 84.1% of the SC>2, 100% of the fur-
fural, and 95-5% of the methanol. The steam rate required for
stripping was 2.3% or 2?.7#'s of steam/1000#'s of condensate
stripped. The S02 is separated, cooled and returned to the
sulfite acid making system. Furfural is recovered at 90% purity
which can be sold as crude but Flambeau purifies it to a 99-5%.
Methanol is recovered with less than 1% water and is suitable
for burning or some industrial uses.
The stripping steam is also used to heat the first effect
of the multi-effect evaporator.
Activated carbon adsorption and ethyl alcohol regeneration
of the carbon removes acetic acid from the condensate and
recovers it as ethyl acetate, which upon concentration by
fractional distillation is brought to 99-5% purity. This part
of the process is still in the development stage.
This report was submitted in fulfillment of grant #S-803
302-01-0 by the Flambeau Paper Co. under the partial sponsor-
ship of the U.S. Environmental Protection Agency. This report
covers the period from June 1976 to June 1978, and the work was
completed as of June 1978.
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CONTENTS
Foreword iii
Abstract iv
Figures vi
Tables vii
Abbreviations and Symbols viii
Acknowledgment ix
1. Introduction 1
2. Conclusions 5
3. Recommendations ..... 7
4-. Operation and Results 8
5. Economic Evaluation 32
6. Analytical Procedures 35
References 36
Appendices
A. Steam Stripping Tables 37
B. Heat and Material Balances Around Fractionators. 4-6
0. Abstracts from Pertinent Patents 57
D. Equipment Sepcifications 59
Glossary 62
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FIGURES
Number
Page
1 Original Design Operation Flowsheet 9
2 Modified Operation Flowsheet -. . 10
3 Carbon Loading Curves 12
4- Carbon Column Regeneration IS
5 Regeneration Curve 9/10/77 19
6 Regeneration Curve 10/18/77 21
7 Mini-Fractionator 24-
8 Purification of Crude Furfural 28
vi
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TABLES
Number Page
1 Predicted Recovery from Flambeau Condensate .... 2
2 Steam Stripping 14
3 Operating Data, 10-Day Trial 32
1A Peed to Steam Stripper 38
2A % Removal by Steam Stripper 39
IB Heat and Material Balance for Steam Stripping . . . 41
2B Heat and Material Baldnce For #1 Practionator ... 43
3B Heat and Material Balance for #2 Practionator ... 44
4B Heat and Material Balance for #3 Practionator
Peed Tank 45
5B Heat and Material Balance for #3 Practionator ... 47
6B Heat and Material Balance for #7 Practionator ... 48
7B Heat and Material Balance for #7 Practionator
92 to 98% Purfural Purity 50
8B Heat and Material Balance for #7 Practionator
.98 to 99.6# Purfural Purity • • 51
9B Heat and Material Balance for #4 Peed Tank .... 52
10B Heat and Material Balance for #5 Practionator • • 53
11B Heat and Material Balance for EtAc Separator
and #6 Practionator 55
12B Heat and Material Balance for #10 Practionator . . 56
vii
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LIST OF ABBREVIATIONS AND SYMBOLS
ABBREVIATIONS
atm Atmosphere
BOD..... 5 day Biochemical
Oxygen Demand
Btms... .bottoms
COD ....Chemical Oxygen
Demand
cond....condenser
disch...discharge
educt...eductors
evap....evaporator
ex exchanger
fig figure
ft feet
fr fractionator
fract...fractionator
fufr....furfural
gal gallons
gpm gallons/minute
hex heat exchangeT>
in inches
I.P.C...Institute of Paper
Chemistry, Appleton,
Wisconsin
kg. . . .
kg/s .
kJ ____
kPa. . .
Ib ----
in • • • •
min. . .
mos. . .
No ____
ovrhd .
reg. . .
regen.
s .....
sec . .
sep . .
stg . .
strip.
T .....
T.P..
.kilograms
.kilograms/sec
.kilojoule
.kilopascal
.pound
.meter
.cubic meter
.cubic meter/second
.minute
.months
.number
.overhead
.regeneration
.regeneration
.second or steam
.second
.separator
.storage
.stripper
. tank
.Treatment Plant
SYMBOLS
C Centigrade
EtAc....Ethyl Acetate
EtOH ...Ethanol
(ethyl alcohol)
F Farenheit
HAc Acetic Acid
H20 Water
MeAc...Methyl Acetate
MeOH...Methanol
(methyl alcohol)
S02-...Sulfur Dioxide
# number or pound
$/hr.. .pound per hour
#/day..pound per day
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ACKNOWLEDGMENT
The Flambeau Paper Co. wishes to acknowledge the Environ-
mental Protection Agency Grant No. S-803302-01-0 of $500,000 to
aid in installing and starting the Demonstration Plant for
"VOLATILE COMPONENTS RECOVER FROM SULFITE EVAPORATOR CONDENSATE",
Mr. Kenneth W. Baierl, Sr. was responsible for developing
much of the technology and invented new cost saving techniques.
Previous work had been done by Mr. Baierl at Scott Paper Com-
pany at Everett, Washington and the Institute of Paper Chemistry
in Appleton, Wisconsin on this recovery process.
Marathon Engineering, Inc. of Menasha, Wisconsin detailed
the engineering and C. R. Meyer & Sons, Co. of Oshkosh, Wiscon-
sin built the demonstration plant.
William A. Dryer, Director of Research and Development and
John D. Michna developed new techniques and contributed to the
success of chemical recovery.
IX
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SECTION 1
INTRODUCTION
If a pulp mill recovers a high percentage of spent sulfite
liquor with modern pulp washing equipment, then the BOD obtained
from the evaporation of this spent liquor will be a large por-
tion of the total BOD discharged from the mill. Several re-
searchers have analyzed condensates and encouraged study of
methods for separating the recoverable materials.
Sulfite evaporator condensate and sulfite digester blow
gas both contain S02» methanol, furfural, and acetic acid. SOo
can be recycled to the acid plant; methanol, furfural, and
acetic acid are all commercial chemicals with established prices
and markets. Previous work in recovery of these chemicals had
been done by the Pulp Manufacturers' Research League, the In-
stitute of Paper Chemistry (IPC), and by Mr. Kenneth W. Baierl,
Sr., of Scott Paper Company. When Scott discontinued work in
this area, Mr. Baierl offered his services to the IPC. IPC
developed a joint research project, IPC Project 3100, which was
cosupported by the U.S. Environmental Protection Agency (EPA),
the Wisconsin Department of Natural Resoureces, and ten pulp
mill organizations. The resulting report by K.W. Baierl, et al.,
was entitled "Treatment of Sulfite Evaporator Condensates for
Recovery of Volatile Components."'' The report reviewed a year's
operation of a pilot plant at a Consolidated Papers Corporation
sulfite mill in Appleton, Wisconsin, and included material, heat
and BOD balances.
The research demonstrated that the process could recover
the four chemicals of interest in reusable and salable form.
The researchers predicted from their work that the process would
reduce BOD in the condensate by 90 percent on clean condensate
and by 60 percent on contaminated condensate.
Samples of evaporator condensates were submitted by sulfite
mills supporting the project. The test results indicated the
amounts of each chemical available in the condensate, as well as
the levels of COD and BOD. Flambeau decided to support further
pilot work in the summer of 1973 to determine if the process
would be worth a full-scale pilot study.
In 1974- a- larger-scale pilot study was performed to develop
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design data for a mill-scale demonstration of the recovery
system and to more accurately determine the expected chemical
yields. These further pilot studies provided design data and
showed a larger chemical recovery potential than was calculated
in 1974- Predicted recoveries are shown in Table 1.
TABLE 1 - PREDICTED RECOVERY FROM FLAMBEAU CONDENSATE
Chemicals to 1973 1974-
be Recovered Ibs/day kg/day Ibs/day kg/day
Sulfur Dioxide
Methanol
Furfural
Acetic Acid (in 1973)
(As Ethyl Acetate in 1974)
2,448
1,320
672
6,216
1,110.4
598.7
304-.8
2,819.6
2,448
2,856
1,560
19,984
1,110.4
1,295.5
707.6
9,064.7
Basis: 44% Hardwood, 56% softwood in Flambeau sulfite pulping
furnish.
An increase in the percentage of hardwood in the furnish
was planned because condensate from hardwood sulfite liquor
evaporation contains more of the desired organic chemicals than
softwood, and because chemical recovery would thus appear even
more attractive.
Final design incorporated certain novel ideas including
those in U.S. Patent No. 4,002,525, filed by Kenneth W. Baierl,
Sr., and assigned to Flambeau Paper Company. This patent is
called "Chemical Recovery from Waste Liquors Utilizing Indirect
Heat Exchangers in Multi-Stage Evaporation Plus Contact Steam
Stripping."2 The proposed process makes steam stripping of
condensates economically attractive by substantially reducing
steam requirements and by improving stripping efficiency. Later
developments during the design work resulted in new concepts,
such as "Chemical Concentration by Adsorption, "3 covered under
U.S. Patent No. 4,016,180. This patent was also filed by
Kenneth W. Baierl, Sr., and assigned to Flambeau Paper Company.
Still further developments included a new concept in fur-
fural purification described in U.S. Patent No. 4,071,398,
entitled "Chemical Concentration by Sequential Activated Carbon
Adsorption and Fractionation."^ This was invented by Kenneth
W. Baierl, Sr., and assigned to Flambeau Paper Company. This
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patent makes it possible to concentrate and remove the crude
90 percent furfural "oil" for further purification to 99.5
percent and to recycle the dilute water solution of furfural
for further concentration.
On April 12, 1974, Flambeau applied to the EPA for a demon-
stration grant of $500,000. The EPA authorized Grant No. S-
803302-01-0 under the name, "Treatment of Evaporator Condensate
for Recovery of Volatile Components" on June 25, 1974. Ralph
H. Scott, Chief, Paper and Forest Industries, was Project
Officer for the EPA. The Project Manager for Flambeau was
Walter A. Sherman, Vice President and Assistant General Manager.
The "EPA Determination of Rights" to the inventions
patented has released the patents to Flambeau Paper Company.
The EPA "deems it to be very much in the public interest to en-
courage development, demonstration, and marketing of said re-
ported inventions as a means, if successful of conservation of
materials, waste load reduction and energy use reduction." This
release was granted on the basis that Flambeau would encourage
the use of these processes by others, for either the recovery
of chemicals or for the reduction of steam and fuel. Flambeau
Paper Company has actively encouraged other pulp mills and in-
dustries to install the Chemical Recovery Plant, but no such in-
stallations have occurred.
The Flambeau evaporator condensate contains about 0.05 per-
cent sulfur dioxide, 0.05 percent methanol, 0.7 percent acetic
acid and 0.05 percent furfural. This stream, which is only
about 10 percent of the total flow to the effluent treatment
plant contributes over 50 percent of the total BOD-. Sulphur
dioxide, methanol, and furfural can be removed by steam strip-
ping. Acetic acid can be adsorbed on activated carbon.
The Flambeau steam stripping system uses the steam required
to operate the evaporators for the stripping process. This
steam and volatile materials are then condensed in the first
evaporator effect. The noncondensibles are sent to our acid
plan where the sulfur dioxide is used to produce more cooking
acid. The first fractionator separates the water from the
methanol and crude furfural. The second fractionator separates
the methanol from the crude furfural. Although crude furfural
can be sold as is, Flambeau uses another fractionator and dis-
tills the crude furfural into a 99.5% pure production for which
the demand is greater.
The acetic acid is removed from the carbon using a non-
thermal regeneration process. The activated carbon is used as
a catalyst, and hot ethanol reacts with the acetic acid to
produce ethyl acetate which is then vaporized out of the carbon.
-------
Should any furfural enter the carbon tower, it is removed by
using a hot ethanol extraction. Four fractionators are used to
recover any unused ethanol and to purify the ethyl acetate.
This process is semi-automated and can "be operated "by two men
on each shift.
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SECTION 2
CONCLUSIONS
This demonstration project can be divided into two parts -
steam stripping and carbon adsorption - both with chemical
recovery.
STEAM STRIPPING
Steam stripping has been-a demonstrated success. Removals
of 100 percent of the furfural, 98.8 percent of the methanol,
84-. 1 percent of the sulfur dioxide, and 40.2 percent of the BOD
sent to the stripper were achieved. A steam rate in the strip-
per was 2.8 percent based on the weight of the condensate. An
additional 0.378 kg/s (3000 Ibs/hr) of steam was necessary to
operate the fractionators to produce methanol with less than 1
percent water, and to produce a 99-5 percent furfural product.
The steam stripper, vent tank, and the first and second
fractionators required for this process require little main-
tenance or supervision. If the fractionators were placed in
the evaporator area, they could be handled by the evaporator
operator. The production of the 99.5 percent furfural, which
is accomplished once or twice a week by vacuum distillation,
requires about 20 manhours of additional labor. This frac-
tionator must be cleaned about three times a year, requiring
30 manhours per clean-up.
The cost of the steam stripper, vent tank, and the #1,2, &
7 fractionators were $878,140 in 1976 dollars. The operating
cost of this unit is $774 per day while the value of the chem-
icals recovered averages $735 per day. The capital cost and
net operating cost may be justified at least in part by the
decrease in the cost of other effluent treatment facilities.
CARBON ADSORPTION
Operating problems arose in the carbon adsorption phase of
this project. The capital cost for the carbon towers, the 4
fractionators, and the necessary tankage was $1,659,838. The
amount of acetic acid converted to ethyl acetate and the
recovery of ethyl acetate in a salable form determines the net
operating cost of this project. While steam stripping can be
operated without carbon adsorption, carbon adsorption can not
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be operated without steam stripping. Therefore, operating cost
for both steam stripping and carbon adsorption must be calcul-
ated together. During the 10 day trial period, we produced
$481 per day of salable chemicals at an operating cost of
$1008 per day. Had we been able to convert all of the acetic
acid into ethyl acetate, we would produce $5519 per day of
salable chemicals at an operating cost of $3134 per day, and
at the same time the BOD load to the treatment plant would
have been reduced by 7710 kg/day (17,000 Ibs.)-
Although ethyl acetate can be produced in commercial quan-
tities with the existing equipment, the life of the carbon
catalyst is a critical question. Conclusions regarding this
aspect of the project include the following:
1. Dirty condensate should not be processed, as some 60 percent
of the spent liquor in this feed is adsorbed by the carbon.
2. Steam stripping was deemed necessary as a preliminary step
to carbon adsorption.
3. Furfural and sulfur dioxide should not enter the acetic
acid adsorption tower, as they will block acetic acid
adsorption sites and shorten carbon life.
4-. The steam used in regeneration must not contain chemicals
which might poison the carbon. One such chemical is
octadecylamine, a filming amine used to prevent corrosion
in steam handling equipment.
5. Channeling in the carbon towers must be recognized.
6. For chemical regeneration, the carbon tower must be relat-
ively small in diameter to provide a suitable vapor velo-
city with a minimum amount of regenerant.
7- If the adsorption of acetic acid can be accomplished without
the loss of carbon life, the return realized from the sale
of ethyl acetate would pay for the operating cost of the
plant.
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SECTION 3
RECOMMENDATIONS
The steam stripping phase of this project with its chemical
recovery has performed well and should be put into commercial
operation.
The carbon adsorption phase of this project will require
further work to prove all of the causes for the loss of carbon
life. This work should be conducted using new carbon. Only
clean condensate which has been steam stripped prior to carbon
adsorption should be used. Care should be taken to avoid intro-
duction of furfural, sulfur dioxide, filming amine, or any other
chemical compound preferentially adsorbed on the carbon active
sites.
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SECTION 4
OPERATION AND RESULTS
During this project two major configurations of the recov-
ery system were used. That shown in Figure 2 was developed to
solve some of the problems which showed up in the initial Figure
1 design where steam stripping was done after carbon adsorption
to recover any ethanol left in the carbon after regeneration.
CONDENSATE SEPARATION
Vent Tank
The condensate streams are separated at the evaporators.
Condensate from the surface condenser is used to wash the
evaporator. It was found that the condensate from the operating
effects of the evaporator contain only about 0.002% sulfur
dioxide by weight. Since the vent tank could not reduce the
sulfur dioxide content below this level, this condensate is not
sent to the vent tank.
The condensate from the 3 condensers which are part of the
vacuum system for our evaporators, is collected and sent to the
vent tank. (Figure 1) This condensate contains between 0.5
to 1.096 sulfur dioxide. It was found early in our work that if
we were to remove the sulfur dioxide, this condensate would have
to be heated to at least 90°C (194°F). To do this a steam
sparger was installed in the bottom of this tank. The vapors
from this tank are condensed in the vent condenser. Sulfur
dioxide does not condense when the water and recovered chemicals
are condensed and the S02 is sent to the acid plant for the
production of calcium base cooking acid. The water and chemicals
are returned to the vent tank from the vent condenser.
During the month of December 1977» records were kept of the
amount of sulfur dioxide being removed by the vent tank. It
averaged 94-.4$ with a maximum of 99.8% and a minimum of 74.6%.
While this method of sulfur dioxide removal is essential, the
variation in the results dictated that a more positive method
of sulfur dioxide removal, such as steam stripping, must be
employed to insure that only a trace amount of S02 would enter
the adsorption towers.
8
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POH fVAM
luSCO ONIV
AfltH VACUUM
DISTILLATION)
roimn.
-------
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>
•* i
>
s
/
r-
J
I
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THI< IMf bSCD ONLY OUHINO
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FIGURE: 2
MODIFIED OPERATION FLOWSHEET
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Surge Tank
The condensate from the vent tank and from the last four
effects of the evaporators are combined and sent to the surge
tank. This tank serves two purposes. It allows the carbon
adsorption tower to be fed at a constant rate. It also provides
storage to hold the condensate which has to be drained from the
tower prior to regeneration and to fill the tower once the re-
generation is complete.
All the condensate is strained to remove suspended solids
before going to the surge tank. These strainers became quite
a problem. When the columns were first started they became
plugged with carbon fines during the first step in regeneration.
Also when the vent tank was not working properly, they plugged
with sulfur compounds. Poly-propylene bag strainers were fin-
ally secured for these strainers which reduced the amount of
time needed for cleaning. Steam stripping prior to carbon
adsorption finally cured the problem.
CARBON ADSORPTION, STEAM STRIPPING #1 AND #2 FRACTIONATORS
Carbon Adsorption
These four units work as a group during the carbon adsorp-
tion cycle. The surge tank condensate, which contains about
0.002% sulfur dioxide, 0.05% methanol, 0.7% acetic acid, 0.05%
furfural, and 0.01% ethanol, is fed to one of the two carbon
adsorption towers. At the start, all of the chemicals are
adsorbed on the carbon (Figure 2;. Once the adsorption sites
are full, acetic acid and furfural easily replace the methanol
and ethanol which break through first and are sent to the steam
stripper for recovery. Acetic acid is next to break through.
Carbon adsorption is considered complete at some point between
where the actic acid first breaks through and where the acetic
acid concentration leaving the tower equals the concentration
being fed to the tower.
Figure 3 shows that the chemical composition of the con-
densate going to the carbon column is never constant. It will
depend on the type of wood cooked, which evaporator is in wash,
the condition of the evaporator with regard to air leakage, and
the length of time since the last clean up. These four sets
of curves show that the acetic acid concentration vary up to
12% during any one carbon loading.
These curves also show that the amount of chemicals which
can be adsorbed on the carbon varies. The higher the concen-
tration of the chemicals going to the adsorption tower, the
greater the amount of chemicals the tower will adsorb. The
11
-------
ro
m3 Condensate Treated
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-------
condition of the carbon plays an important role. If the ad-
sorption sights are blinded by spent liquor, sulfur dioxide,
furfural which is not removed during a regeneration, or in our
case contaminated steam used for purging the tower, then
adsorption will be reduced. Likewise, if there should be
channeling in the tower either during the adsorption phase or
the regeneration phase, the adsorption capacity of the carbon
tower will be reduced. The type of carbon used and whether it
is new or thermally regenerated may also affect adsorption.
When the plant was started with new carbon, we were able to
adsorb the chemicals from about 378 m5 (100,000 gal.) of
condensate before the acetic acid would break through. Toward
the end of the project, the acetic acid break through was oc-
curring between 151 m3 to 227 ^3 (40,000 to 60,000 gal.) of
condensate. If we were to operate on a continuous basis, it
would have been necessary for us to treat about 340 m3 (90,000
gal.) of condensate before break through under ideal conditions
or 4-92 m3 (130,000 gal.) under normal operating conditions. We
were not able to consistently maintain either of these goals.
Figure 3 illustrates the importance of a thorough regeneration
prior to an adsorption. On April llth, almost 286 cubic meters
(65,000 gal.) of condensate was treated before break through.
On April 15th, using the same carbon, only 132 cubic meters
(30,000 gal.) of condensate was treated before break through.
This shows that prior to the April 15th adsorption, many of the
carbon adsorption sights were not available to adsorb acetic
acid because of a poor regeneration.
During the final three months of operations, octadcylamine
was removed from the steam. Sight glasses were set up both at
the evaporators and the recovery plant to monitor condensate
going to the carbon column. If the condensate was not colorless
it was sent directly to the effluent treatment plant. The
condensate was stripped before going to the carbon towers.
These steps have increased the amount of liquid which could
be treated prior to regeneration, but only the replacement of
the carbon by new or thermally regenerated carbon will provide
full adsorption capacity.
Steam Stripping
Except for the last three months, the treated condensate
leaving the carbon towers was sent to the steam stripper for
enrighment. Steam on the way to the multiple effect evaporator
was used as the stripping steam. &U.S. Patent #4002525) (Fig-
ure 1). This allowed the use of 33% stripping steam in the
stripper. Of this stripping steam used, 96.4% was recovered for
operating the evaporators. As this steam passed through the
stripper, it removed all of the alcohols, acetates, and any
furfural which remained in the treated condensate. The stripped
condensate was then sent to the effluent treatment plant.
13
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During December 1977? samples taken on the feed to and on
the effluent from the steam stripper showed:
TABLE 2 STEAM STRIPPING
To Steam Stripper % Removed "by
kg/24- Hr. #/24 Hr. Steam Stripper
BOD
MeAc
MeOH
EtOH
HAc
Furf.
B00
7,721
10
631
327
4,44-5
417
16
17,021
22
1,392
720
9,800
920
36
40.2
100
98.8
100
42.4
100
84.1
The steam stripper effectively removes all of the methyl
acetate, methanol, ethanol, and furfural from the condensate.
The use of the vent tank prior to steam stripping cuts the
SOo to less than 3 kg (6#) per 24 hours. These results then
show that this is an effective method of keeping unwanted
chemicals off carbon adsorption sites.
Originally plans were made to use this purified condensate
back into the pulping system. The presence of carbon fines in
the condensate, which would contaminate the pulp, prevented
this. The rubbing of the carbon together during regeneration
produces fines, and periodically these fines showed up in the
stripped condensate.
#1 Fractionator
The vapors from the steam stripper were condensed in the
first evaporator effect. This condensate was then sent to the
chemical recovery plant and became feed for the #1 fractionator.
The #1 fractionator separates most of the water and acetic
acid from the alcohols, furfural and sulfur dioxide (Figure 1).
Originally it was planned that this fractLonator should remove
all of the water. To do this required too much steam. When
this fractionator is operating properly, the bottoms contain
0.26$ acetic acid with the other chemicals being undetectable.
These bottoms are sent through a heat exchanger to help heat the
feed to the steam stripper and then to our effluent treatment
plant. The overhead from this fractionator contains 27% meth-
anol, 0.65% furfural, 21% ethyl acetate, 21% ethanol, and 2.6%
sulfur dioxide. This is used for the feed to #2 fractionator.
-------
All of the fractionators had common problems during start-
up. All of the vent condensers from each fractionator dis-
charged into a common header. As each fractionator "breathed,
vapors from one fractionator would "be pushed into or sucked
out of the common vent line. This in turn would upset the
boiling point of the liquid at the top of another fractionator
and cause a violent reaction blowing liquid into as many as
three additional fractionators. Then all the fractionators
would blow their overhead to the atmosphere. Temporary sep-
arate vent lines and finally permanent separate vent lines
were installed to each fractionator.
Another problem common to all of these fractionators was
that each fractionator was operated by three control loops. The
pressure drop through the packing controlled the steam. The
temperature near the top of the column controlled the valve
which regulated the take off from the overhead of the column.
The level in the reboiler controlled the take off from the
bottom of the fractionator.
The problem with this type of control was that if too much
product was removed from the top of the fractionator, the pres-
sure drop through the column would be reduced and this would
call for more steam to be applied to the reboiler. Water vapor
develops very little pressure drop through the packing. Alcohol
and other more volatile chemical vapors develop a much higher
pressure drop. This additional steam would increase the boil-
up rate. This in turn would increase the liquid level in the
condenser and finally a point would be reached where the liquid
would cover the discharge line to the vent condenser. Now
pressure would build up in the column and force liquid through
the vent condenser into the atmosphere.
The tap at the bottom of the column for sensing the pres-
sure was located directly across from the discharge of the
reboiler. This location forced liquid into the pressure tap
and gave a false high pressure reading which would close the
steam valve and cause the fractionator to drop without the
operator being aware of the problem.
During the shutdown from October 1 to October 23, 1976,
the following changes were made to correct these problems.
1. The deisgn of the condensers provided for the overhead to
be drawn off the bottom of the condenser and the reflux
came from the overflow pipe at the side of the condenser.
The thermal well was placed below the reflux line and un-
less product was being drawn off, the temperature at the
thermal well did not change. These thermal wells were
moved into the reflux line to insure continous temperature
reporting for the operators in the control room.
-------
2. Air purges were installed on all of the pressure and level
sensors in the fractionators to eliminate false pressure
reports due to liquid in the lines.
3. High temperature cutoff controls were installed on the #1,
#2, #3, and #5 fractionators to prevent takeoff of overhead
once the temperature at the top of the fractionator reached
a set point, this insured us of a minimum pressure drop
through the packing and prevented the reboiler's steam
valve from opening wide open.
The primary cause of the October 1st shutdown was the dis-
ruption of the packing in #1 fractionator. The combination of
an organic sulfur compound which built up in the packing,
coupled with the violent steam surges during the" time that the
vent lines were tied together, caused the top three rings of
packing to unroll. These were sent back to the company for
repair and rewinding-. To prevent this from happening again,
a regular program of boiling this fractionator out with caustic
was instituted to remove this organic sulfur build-up. Hold
down bars were installed on the top of this fractionator to
keep the packing from rising. Steam stripping prior to carbon
adsorption appeared to eliminate the organic sulfur buildup in
the packing.
#2 Fractionator
This fractionator was designed to separate the ethanol
from the methanol coming from the overhead of #1 fractionator
(Figure 1). Because of the water and furfural in the feed to
this fractionator, a line was installed to send the bottoms of
this fractionator to #3 feed tank rather than to the regener-
ation tank. The bottoms from this fractionator contained about
4-5.2% ethanol and 1.4$ furfural with the remainder water. The
overhead from this fractionator contained about 51-9% methanol,
4.°$sulfur dioxide, W.7% ethyl acetate, and 2.596 methyl ace-
tate. Because of the sulfur dioxide, this product had limited
commercial value except as fuel.
Because of the low water content in the feed and the slow
feed rate, this fractionator presented no operational problem.
Once it was decided to steam strip prior to carbon adsorp-
tion, only furfural, methanol, acetic acid, and water went to
#1 fractionator (Figure 2). This fractionator separated the
methanol and furfural from the acetic acid and water. No. 2
fractionator then could separate the methanol from the furfural
and water. The furfural water mixture at the bottom of #2
fractionator contained over 30% furfural and no alcohol. Once
these bottoms were cooled, this permitted us to by-pass #3
and 7 fractionators and go directly to the furfural day tank.
16
-------
Carbon Regeneration
During the carbon adsorption phase, the condensate flows
upwards through the tower. Furfural collects near the bottom
of the tower and the acetic acid is distributed throughout the
tower. Once acetic acid breaks through the carbon and the
condensate flow is sent to the second tower, the loaded tower
is ready for regeneration (Figure 4-).
Most of the regenerations were accomplished in the follow-
ing manner. The tower was drained back to the surge tank while
adding either vaporized or liquid ethanol to the top of the
tower. The ethanol displaces some of the water which had ad-
hered to the carbon and also comes into intimate contact with
the acetic acid adsorbed on the carbon. As soon as the conden-
sate is drained from the tower and heat is applied to the carbon
in the form of ethanol vapor, the following reaction takes
place and ethyl acetate is formed.
EtOH + HAc >- EtAc + HpO
Some of the ethanol condenses andrefluxes at the bottom
of the tower. This hot liquid ethanol dissolves and removes
the furfural from the bottom of the tower. After 22.7 m^
(6,000 gal.) of ethanol has been used, the addition of ethanol
vapor to the column is stopped and steam is added in an upward
flow. This drives off the ethyl acetate and ethanol mixed with
varying amounts of water from the top of the tower. These
vapors are condensed in the regeneration condenser. This liquid
is stored in one of two tanks for further processing.
The #3 storage tank receives all of the liquid removed
from the bottom of the carbon tower during regeneration. It
also receives any liquid from the regeneration condenser which
contains more than 12% water. This tank is also used to collect
the bottoms from the #2 fractionator, the underflow from #5
separator, any alcohol removed from #7 fractionator, the con-
densate from the eductors on #7 fractionator and the bottoms
from #10 fractionator (Figure 1).
If the condensed liquid from the regeneration condenser
contains less than 12% water, it is sent to the #4- fractionator
feed tank.
During the course of regeneration, the products obtained
from both the bottom and the top of the tower vary greatly
with time. The nearly vertical lines on Figures 5 and 6 show
the times when high volumes of chemicals are extracted. The
nearly horizontal lines show that very little chemical is ex-
tracted. Figure 5 shows a regeneration during which most of
the ethyl acetate and furfural were removed from the carbon.
17
-------
TO NO. 3 FEED TANK
TO NO. 4 FEED TANK
TO REGENERATION TANK
•*•
TO NO. 3
FEED TANK
TO SUR6E
LEVEL TANK
TANK
oo
STEAM
EtOH FROM
REGENERATION
TANK
ETHANOL
VAPORIZOR
REGENERATION
CONDENSER
CARBON
STEAM FIGURE 4
CARBON COLUMN REGENERATION
-------
Total
Lb. of Liquid Recovered
During Regeneration
No, 1 Carbon Tower 9/10/77
* * r x
3 6 9 12
Hours of Regeneration
Figure
Regeneration Curve 9/10/77
19
-------
The steep slope of the ethanol line and the nearly horizontal
water line shows that the regeneration was stopped before all
of the ethanol was purged. Figure 6 shows a regeneration
during which most of the ethyl acetate, furfural, and acetic
acid was removed from the carbon. The steep slope of the water
curve and the nearly horizontal slope of the ethanol curve
shows that the regeneration should have been stopped sooner.
By extending this regeneration, extra liquid which was mostly
water had to be processed by our No. 3 fractionator. This in
turn forced us to delay the start of the next regeneration until
the excess liquid was processed.
These towers were designed with timers and automatic in-
struments so that the regeneration could be programmed. In
practice this did not work. The draining of the tower created
the first problem. A vent line had to be installed between the
level tank and the regeneration condenser to keep the level tank
from air binding. The valve in this line could not be opened
before the liquid level in the carbon tower was below the bottom
of the regeneration condenser or this condenser would flood.
If this valve was not opened soon enough, then the vacuum in
the top of the tower would keep the liquid from being pumped
to the surge tank.
The level sensing switches at the top of the carbon towers,
which signaled the control room when the tower was full, proved
to be inadequate. The balls on the original float switches
collapsed under alternate pressure and vacuum. One of the spare
vents at the top of each tower were used to install new probe
type switches.
The pressure switches which controlled the steam and the
ethanol vapor to the tower were not sensitive enough to prevent
the blowing of rupture disks in the lines going to the tower
when steam or ethanol vapor started flowing into the tower.
Prom November 1, 1976 through January 12, 1977» the Recovery
Plant was shut down for lack of steam. This was the year of the
severe natural gas shortage. The federal government prohibited
the use of natural gas for electric power generation and this
rule was applied to gas turbine generators. The local utility
had such a generator with a waste heat boiler which supplied
9.4-5 kg./s (75,000#/hr.) steam to the Flambeau Paper Co. With
this supply cut off, our company suffered a steam shortage
which could not be corrected until a package boiler was leased
and brought on line on January 12, 1977- During this time,
the recovery plant was shut down. Only steam for heating the
building and for tracing the liquid lines was used. The carbon
towers were drained and steam was bled through them to prevent
them from freezing. Oxidation of the sulfur dioxide trapped
20
-------
o
C-
o
vO
»d
o
o
3
•d
o
fc
P4 O
ITT
H
O
fl
•d
o
o
3
•d
o
h
PH
J
Total
Lb. of Liquid Recovered
During Regeneration
No. 1 Carbon Tower 10/18/77
3i ' • 6
Hours of Regeneration
Figure 6 , Regeneration Curve 10/18/77
21
-------
in the carbon formed sulfuric acid which corroded the bottom
strainers. When these strainers leaked, carbon filled the feed
tanks and plugged up the fractionation columns. The system had
to be shut down, the carbon removed from the towers, and the
strainers at the bottom of these towers replaced and the towers
refilled with carbon. It also necessitated the cleaning of the
feed tanks and of #3 and #5 fractionators.
During June of 1977? one of the carbon towers was struck
by lightning. The lightning on its way to the ground melted
two of the bottom strainers at the base of the tower. As soon
as it was discovered that granular carbon was escaping from
the bottom of the tower, the tower was shut down and the carbon
removed. This time the carbon was sent back for thermal regen-
eration. To prevent strainer problems in the future, the
strainers were replaced with perforated pipes. Graded gravel
and sand were placed around and over these pipes to form a
base for the carbon. This tower was then filled with new car-
bon. When the thermally regenerated carbon was available, the
other tower was emptied and the bottom strainers were protected
with graded gravel and sand before being refilled with the
thermally regenerated carbon. These changes solved the internal
strainer problem.
Carbon life still remained a problem. To correct this, a
major process modification was started in March of 1978* Con-
densate was stripped prior to carbon adsorption (Figure 2).
This removed sulfur dioxide, methanol and furfural from the
feed.
Spent sulfite liquor was prevented from reaching the car-
bon. Sight glasses were installed in the lines leading to the
surge tank both at the evaporators and at the recovery plant.
As soon as it was discovered, either operator could divert cont-
aminated condensate directly to the effluent treatment system.
These changes prevented further deterioration of the car-
bon during the next 40 regenerations. It also reduced the
amount of alcohol required to leach the furfural and spent
liquor from the carbon. The elimination of methanol prevented
the formation of methyl acetate and the elimination of sulfur
dioxide reduced the organo-sulfur problems we. were'having in
fractionators No. 5,6, and 10.
During the last 10 days that the plant operated, it pro-
duced at a consistent rate without an upset. An average of
0.37m (83-5 gal. or 964 Ibs.) of ethyl acetate, 226.8 kg (500
Ibs.) of 99# furfural and 0.41 m.5 (94 gal.) of methanol were
produced each day. A regeneration was completed in twelve hours
for the first time.
22
-------
Since we did not have to remove furfural or spent sulfite
liquor from the carbon, the amount of alcohol used during the
regeneration was reduced. It is now felt that if a mini-
fractionator (Figure 7) were installed between the level tank
and the regeneration condenser, some of the alcohol which now
goes to the No. 3 feed tank would be fractionated and go to
the No. 4 feed tank. This would reduce the concentration of
alcohol in the No. 3 fractionator feed, increase the through-
put of this fractionator and put us one step closer to our
goal of a continous process.
FRACTIONATORS #3 AND #7
The products of regeneration are separated and purified
through a series of fractionation steps using five fractionators.
Fractionator #J>
Fractionators #3 and #7 are used for removing water and
furfural from the regeneration products (Figure 1). The #7
fractionator serves a dual purpose, atmospheric fractionation
and vacuum distillation.
The #3 fractionator is fed from the #3 feed tank at a
rate between 0.00252 to 0.00757 m3/s (4- to 12 gpm) depending
on the amount of alcohol and acetates contained in the feed.
Furfural and water leave with the bottoms. The ethanol, ethyl
acetate and methanol are rectified and leave from the top of
the column. The furfural and water from the bottom of the
column are sent directly to the #7 fractionator as feed. The
ethanol, ethyl acetate, methanol and a trace of water are re-
moved from the top of the column and sent to the #4- feed tank
for further purification.
The operation of #3 fractionator is very critical. An
alcohol layer must be kept just above the furfural layer in
the fractionator to force the furfural to the bottom of the
column. This is accomplished by limiting the amount of alcohol
drawn off the top of the fractionator. If the draw off from
the top of this fractionator is too slow, alcohol will work its
way into the stripping section of the column, and some alcohol
will be discharged to the #7 fractionator. This alcohol will
finally end up in the day tank of #7 fractionator and prevent
the separation of the 90i& furfural crude.
If the draw off from the top of the fractionator is too
fast, the furfural will move up the column into the rectification
section and be discharged from the top of the column. It will
then end up with the recovered ethanol from the bottom of #5
-------
CARBON
TPWEK
STEAM
REGENERATION
CONDENSER
REFLUX
MINI
FRACTIONATOR
NO. 3
FEED
TANK
IF< 12% H20
H20
SURGE
TANK
NO. 4
FEED
TANK
FIGURE 7
MINI - FRACTIONATOR
-------
fractionator and become distributed through the activated carbon
during the next regeneration. Furfural takes up acetic acid
adsorption sites on the carbon, and if the furfural is near the
top of the tower, it is very difficult to remove.
The design of #3 fractionator failed to allow enough theor-
etical plates in the stripping section of this column to allow
the separation of the alcohol from the furfural and water.
During the October 1976 shutdown, 1.82 m (6 ft.) of packing was
moved from the rectification section to the stripping section
of this column by interchanging the 2nd and 3rd sections of this
fractionator. This allowed us to operate, but it made the
column difficult to handle due to the loss of theoretical plates
in the rectification section.
The heat exchanger originally installed between the bottom
of #3 fractionator and the feed plate of #7 fractionator was
removed due to fouling. The polymerized material from the
bottom of #3 fractionator plugged the tubes in this heat ex-
changer.
The safety outlet valves in #3 and #4- feed tanks had to
be replaced because they did not contain 100% stainless steel
parts. Wisconsin law required that both the inlet and the dis-
charge pipes from all tanks containing volatile materials must
be at the bottom of the tank. This caused short circuiting
and improper mixing of the chemicals in #3 and #4- feed tanks.
This situation was partially corrected by installing recircu-
lation lines in each of these tanks.
It required 8 to 12 hours to get a satisfactory separation
in the #3 fractionator when it is just starting up. Lines were
installed to allow off quality products from both the bottom
and the top of this fractionator to be recycled back to the #3
feed tank so that during startup this fractionator would not
have to be run on total reflux. This allowed for a faster
buildup of chemicals in the system and this fractionator could
then be brought on line in less than 3 hours.
It was found that the chemical recovery plant did not have
a reliable source of cooling water for the condensers. A larger
cooling water pump with a pressure reducing valve was installed
to correct this problem.
Steam stripping prior to carbon adsorption eliminated
furfural from this fractionator (Figure 2). This simplified
the operation of this fractionator and allowed the bottoms to
be discharged directly to our effluent treatment plant.
Fractionator #7
The #7 fractionator separates the furfural from the water.
25
-------
Furfural at a concentration of 22% with water forms an azeotrope
and boils at about 98°C (208°F) and is removed from'the top of
the column. This is cooled and sent to the day tank where 90%
furfural settles to the bottom and 12% furfural layers on the
top. This 12% furfural solution is then returned to the frac-
tionator as reflux. By applying between 0.038 to 0.088 kg/s
(300 to 700#/hr.) of steam, the furfural is stripped from the
liquid descending the column. About 0.5% furfural and 1.5%
acetic acid together with the spent liquor and the polymerized
material are discharged in the bottoms. These bottoms are
returned to the surge tank so that they would be treated by
the carbon towers to recover the furfural and acetic acid be-
fore being discharged.
It is necessary to keep air from coming in contact with
furfural. Air and furfural heated will polymerize. To prevent
plugging of the tubes in the reboiler, a trap was placed before
the pump and a strainer was placed in line after the pump to
collect this polymerized material. This solved the tube fouling
problem.
Another problem with the #7 fractionator was that this
polymerized material would plug the packing. Experimentation
showed us how to clean this packing easily using chemicals.
When the method was perfected, we were able to disassemble,
clean the packing and reassemble the column during an 8 hour
day.
Steam stripping, prior to carbon adsorption, eliminated
the need for using our No. 7 fractionator to concentrate the
furfural to 90%. The bottoms from No. 2 fractionator went
directly to the furfural day tank where it separated into two
layers, one containing 90% furfural.and the other 12% furfural.
The 12% furfural layer would leave from the top of the day
tank and be returned to the No. 1 fractionator for reprocessing
(Figure 2). This change, not only saved steam, but also re-
duced the plant's maintenance problems. It allowed work on
No. 7 fractionator without a complete plant shut down. No. 1
and No. 2 fractionators work very well this way and remove 99%
of the methanol and furfural fed to them.
FURFURAL PURIFICATION
No. 7 Fractionator Vacuum Distillation
The #7 fractionator was built to operate under either
atmospheric or vacuum conditions. This dual use of the same
fractionator is covered by U.S. Patent. #4-071398. A 22% furfural
water azeotrope boils at 98°C and will separate on cooling into
two layers, one containing 90% furfural, the other 12% furfural.
26
-------
Vacuum distillation of the 90% furfural produces 99.5% furfural.
When sufficient 90% furfural has been collected from the
operating of the #7 fractionator under atmospheric conditions,
this fractionator is taken off line and the bottoms of the #3
fractionator are returned to the surge tank where it again
goes through the carbon tower and furfural is readsorbed
on the carbon. The #7 fractionator is drained and pumped back
to the surge tank and the kettle at the bottom of this fraction-
ator is filled with 90% furfural from the furfural day tank
(Figure 8). As heat is applied to the liquid in the kettle, a
vacuum is drawn on the column to prevent the temperature from
exceeding 100°C. Should the furfural go over this temperature,
it will start to decompose.
Initially the 22% furfural water azeotrope boils off the
90% furfural in the kettle. As the per cent of water in the
kettle decreases, more and more furfural is boiled off with the
water and the temperature in the kettle rises. These vapors
are condensed and stored in the day tank where they separate
back into layers of 90% furfural and 12% furfural. This is
saved and used for the next vacuum distillation.
The composition of the overhead from the top of this frac-
tionator is continually sampled and tested. When the water
content in the overhead drops to less than 0.5%, the liquid
from the condenser is stored in drums as the final product.
Distillation is continued until there is only about 0.22m3
(50 gal.) of material left in the kettle. At this time the
steam is shut off and the contents of the kettle, with its
impurities are returned to the spent sulfite liquor feed tanks
ahead of the evaporators for reprocessing. Feed from the
bottom of the #3 fractionator is again sent to #7 fractionator
and the #7 fractionator is again put on atmospheric distillation
and the collection of furfural is resumed.
FRACTIONATOBS #», #5, #6, AND #10
These fractionators are used to produce pure ethyl acetate
and to recover unreacted ethanol (Figure 2). There is little or
no sale for contaminated ethyl acetate. Unreacted ethanol must
be recovered and returned to the regeneration tank for reuse.
Discontinued #4- Fractionator
The #4- fractionator was originally designed to remove the
methanol from the ethyl acetate-ethanol-water solution. The
methanol was supposed to leave from the top of the fractionator
while the ethanol, ethyl acetate, and water were to leave from
the bottom of this fractionator. The ethyl acetate and the
methanol did not separate. Even if we allowed 3 parts of ethyl
-------
I
00
<5 1
^xC^
No. 7
^><^
}
KETTU
7\ l\f\
PAY
TVJWK
71
TO PffUMS
FIGURE 8
PURIFICATION OF CRUDE FURFURAL
-------
acetate to escape with 1 part of methanol, there was still
methanol being discharged from the bottom of the column.
Also, there was no logical place to go with the material
removed from the top of the fractionator. If it was sent back
to #3 feed tank, the methanol in the system would build up. If
it was sent to the surge tank or to #1 or to #2 fractionators,
the ethyl acetate would contaminate the methanol product. There-
fore, the piping was changed and this fractionator was elimi-
nated.
Fractionator #5
The #5 fractionator was designed to separate the ethyl
acetate from the ethanol and water. The feed to this fraction-
ator comes from the discharge from the top of #3 fractionator
and at certain times from the regeneration condenser. It is
important to keep this feed at less than 12% water. If there
is too much water in the feed, it will dilute the ethanol at
the bottom of the fractionator and thus dilute the ethanol
going to the regeneration tank.
The maximum feed rate was never established because the
#3 fractionator limited the rate of feed to this fractionator.
The usual feed rate to this column was between 0.000126 to
0.000252 m3/s (2 to 4- gpm). The ethyl acetate-ethanol-water
azeotrope together with the methanol and any sulfur dioxide
worked its way through the rectification section of this frac-
tionator and was sent to the ethyl acetate separator. The
remaining ethanol and water dropped through the stripping
section, was cooled, and then sent to the regeneration tank
to be used for the next chemical regeneration.
This fractionator worked very well once separation was
obtained. For this reason, we try to never shut this fraction-
ator down.
Ethyl Acetate Separator
The condensed liquid from the top of #5 and from the top
of #6 fractionator are combined and water is added to this at
the rate of 0.0000126 m?/s (0.2 gpm). Then it is cooled and
sent to the ethyl acetate separator where the ethyl acetate
separates from the wash water. The washing of the ethyl acetate
with water removes the ethanol and methanol and purifies the
product. The ethyl acetate from the top of the separator be-
comes the feed for the #6 fractionator while the bottoms are
recycled.
At first the liquid from the bottom of the separator was
returned to the #3 feed tank. With the #4- fractionator removed
29
-------
from the system there was no way for the methanol to escape.
A new line was installed so that these bottoms could be sent to
the feed of the #1 fractionater. It was hoped that with the
large amount of water in #1 f ractionator that the ethyl acetate
would break down and revert back to acetic acid and ebhanol.
This did not happen and the methanol was further contaminated.
In order to salvage some of this ethyl acetate, the bottoms of
the ethyl acetate separator were sent to the #3 feed tank so
long as the methanol concentration was no greater than 8%.
Once the methanol concentration rose above 8%, the bottoms had
to be sent to the #1 fractionator feed.
Steam stripping, prior to carbon adsorption, eliminated
the need for our #4 f ractionator. We no longer had to contend
with sulfur dioxide and methanol in the feed to our #5 frac-
tionator. This in turn eliminated the sulfur dioxide and
methanol from the ethyl acetate separator. It had been found
that if the sulfur dioxide content in this separator became too
high, the two phases in the separator would invert and water
would enter #5 f ractionator. Once this happened, it would
take several days before we could eliminate the water from
that fractionator and start producing 99+% ethyl acetate again.
The elimination of methanol from these streams allowed us to
return the water phase from the bottom of this unit to the #3
feed tank. This in turn eliminated the ethyl acetate from
the #1 and 2 fractionators and the methanol product.
#6 Fractionator
The #6 fractionator was designed as the final step in the
purification of ethyl acetate. The. small amount of water and
ethanol in the feed to #6 fractionator formed an azeotrope with
ethyl acetate which lowered the boiling point to below.that of
pure ethyl acetate. This allowed the water and ethanol to be
removed from the top of this column. This overhead was then
returned to the ethyl acetate separator. Pure ethyl acetate
from the bottom of this column was to be stored in the ethyl
acetate storage tank.
#10 Fractionator
During this process, yellowish organic: sulfur compounds
formed and remained with the ethyl acetate. To remove the
yellow color, the No. 4- fractionator was used after the No.
6 fractionator and renamed No. 10 (Figure 2).
This column produced colorless 99-5% ethyl acetate at the
top and the yellow color which collected at the bottom was
pumped back to the no. 3 feed tank about once every 24 hours.
It is estimated that 0.057 m3 (15 gal.) of ethyl acetate was
recycled each time the bottoms of the No. 10 fractionator was
50
-------
pumped out. It has "been noted that since we started steam
stripping prior to carbon adsorption, that the color in the
ethyl acetate is gradually disappearing. If this trend con-
tinues, it could mean that this fractionator might not be
needed for this purpose.
Material Balances
Material balances showing the operation of the steam
stripper and the fractionators can be found in Appendix A.
These tables show average values only. The concentration of
the various streams are continually changing through the
regeneration cycle.
31
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SECTION 5
ECONOMIC EVALUATION
Being a first generation plant, engineering, consulting
and construction costs were high. Many items included in the
original design, were later found unnecessary. Engineering
and consulting services for this project were $591>324. Con-
struction costs were $2,537,978.
Near the end of the project, a 10 day trial was conducted.
Caustic cleaned carbon was the only carbon available to us for
this trial. Laboratory tests showed that it would adsorb only
9-7!# ,as much acetic acid as would new Witco Carbon, and only
as much acetic acid as thermally regenerated carbon.
TABLE 3. OPERATING DATA, 10-DAY TRIAL
Stream/
Compound
Gal./
Day
m5/
Day
Lbs./
Day
Theoretical
kg/ Recovery
Day
1974
Input 230,000 870.642
Output, Salable
Sulfur Dioxide 1,770 804.5 72.3
Methanol 94 0.34 620 281.18 21.7
Furfural 500 226.76 32.1
Ethyl Acetate 126 0.45 964 929.02 4.8
The economic analysis of this run was based on the follow-
ing process. One kg (2.205 lb.) of ethyl acetate requires 0.52
kg (1.147 lb.) of ethyl alcohol and 0.68 kg (1.50 lb.} of acetic
acid. Ethyl alcohol costs about $0.375/kg ($0.17/lb.), and the
Srice for ethyl acetate delivered is $0.507/kg ($.23/lb.) minus
0.088/kg ($0.04/lb.) for transportation and commission, giving
a net price of $0.419/kg ($0.19/lb.). Only fuel value can be
give to the methanol, as what was produced was contaminated
with sulfur dioxide and could not be sold. The sale prices of
the products produced each day were:
32
-------
429.02 kg Ethyl Acetate x $0.4l9/kg $179.76/Day
226.76 kg Furfural x $1.19/kg
281.18 kg Methanol x $0.044/kg
804.50 kg Sulfur Dioxide x $0.023/kg
270.00/Day
12.51/Day
18.30/Day
TOTAL SALE PRICE $480.77/Day
Operation Cost of the plant was:
Steam
Labor
Maintenance
Ethanol
$576.00/Day
300.00/Day
48.00/Day
84.00/Day
TOTAL COST OP OPERATION $l,008.00/Day
This operation removed 2.544 kg/day (5,610 Ibs./day) of
BOI>5. The net operating cost was $527.23/day or 9.40/lb. of
BOD removed.
Further modifications of the process shown in Figure 2 in-
clude addition of the Mini-Fractionator shown in Figure 4. The
Mini-Fractionator is designed to fractionate the regeneration
products so that more product with less than 12 percent water
is produced, reducing the bottlenecking effect of Fractionator
No. 3« If 100 percent removal of methanol, acetic acid, and
furfural could be obtained with new carbon, then the following
economic balance would apply:
Methanol at a concentration of 0.071% 618.16 kg/Day
Acetic acid at a concentration of 0.894 7»783.54 kg/day
Ethyl Acetate (7.783-54 x 1.467) 11,418.45 kg/Day
Furfural at a concentration of 0.067% 583-33 kg/day
Ethyl acetate (11,418.45 x $0.419)
Furfural (583-33 x $1.19)
Methanol for fuel (618.16 x $0.066)
4,784.33/Day
694.16/Day
40.80/Day
TOTAL SALE PRICE 5,519•29/Day*
Operating cost for this plant would be:
Steam
Labor
Maintenance
Ethanol
576.00/Day
300.00/Day
48.00/Day
2,210.00/Day
TOTAL COST OF OPERATION $ 3,134.00/Day
This would allow the plant to net $2,385.29 per day
while reducing the BODc load to the treatment plant by 7709-75
kg (18,000 Ib.) per day.
33
-------
*Income from the sale of S02 is not included since some of the
S02 would be used in water to wash the scale out of the evapor-
ator so that none of the organic chemicals would bypass the
recovery equipment.
-------
SECTION 6
ANALYTICAL PROCEDURES
The Hewlett Packard 5830A gas chromatograph was fitted
with dual thermal conductivity detectors fitted with two 12 foot
by 1/8 inch diameter stainless steel columns which were used to
determine the percent by weight of methyl acetate, methanol,
ethanol, ethyl acetate, acetic acid, and furfural in the samples.
These columns were packed with 5% carbowax 20M on JO/60 mesh
Chromosorb T. Samples were tested using the following program:
The initial temperature of 80°C was held for 5 minutes. Then
the temperature increased at the rate of 30°C per minute until
180°C was reached. This temperature was held for 5 minutes to
complete the test. The injection temperature was 190°C, the
detector temperature was 230°C, the attenuation was 9» the
helium carrier flow was 11 ml/min. and the injection size was
0.3 microliter. Using this method, 3 samples per hour could be
tested.
The gas chromatograph was standardized using different
concentrations of the pure chemicals and the factors were
incorporated into the computer program of the gas chromatograph
so that the results were directly printed out by the chromato-
graph. The operator ha^ to inject the sample and edit the
proper times when the chemicals came out into the computer. If
he was uncertain about the chemical composition of a peak, he
would spike the sample with a known amount of the suspected
chemical and rerun the sample. If the suspected peak increased
in size, then he 'knew that he had the right chemical.
Sulfur dioxide was determined by titration with standard
potassium iodate to a blue starch end point.
In special cases, where it was known that only acetic acid
was present, the concentration was determined by titration with
a standard sodium hydroxide solution. This was done because
acetic acid had the tendency to hang up in the column of the
gas chromatograph and several successive samples had to be
tested to insure a correct reading. This method also relieved
the load on the gas chromatograph and allowed it to be used
for testing other samples.
-------
1. Baierl, Kenneth ¥., et al, "Treatment of Sulfite Evaporator
Condensate for Recovery of Volatile Components," prepared
for the U.S. Environmental Protection Agency, Office of
Research and Development, EPA Grant No. S801207, November
1973. EPA-660/2-73-030
2. Baierl, Kenneth W., U.S. Patent No. 4,002,525, Chemical
Recovery from Waste Liquors Utilizing Indirect Heat Ex-
changers in Multi-Stage Evaporation Plus Contact Steam
Stripping," assigned to Flambeau Paper Company, January 11,
1977-
3. Baierl, Kenneth W., U.S. Patent No. 4,016,180, "Chemical
Concentration by Adsorption," assigned to Flambeau Paper
Company April 5, 1977.
4. Baierl, Kenneth W., U.S. Patent No. 4,071,398,"Chemical
Concentration by Sequential Activated Carbon Adsorption
and Fractionation," assigned to Flambeau Paper Company,
January 31, 1978.
5. U.S. Environmental Protection Agency, "Determination of
Rights: Grantee-Reported Inventions," EPA Grant No.
8803,301-01-02, Flambeau Paper Company, November 4, 1977-
-------
APPENDIX A
STEAM STRIPPING TABLES
These tables show the average feed to and the percent
removal "by the steam stripper for BODc and certain chemicals
during the month of December 1977-
37
-------
TABLE 1A. PEED TO STEAM STRIPPER
00
SENT TO STEAM STRIPPER
DATE
Dec.
1977
9
10
12
13
14
16
17
19
20
21
22
BOD
7709
6587
6221
10516
6930
7908
7995
7575
6277
84-53
794-8
16996
14-543
13715
2274-3
15277
174-36
17626
16700
13838
18635
19728
MeAc
kg
0
0
0
0
0
0
4-9
0
0
0
63
«
0
0
0
0
0
108
0
0
0
139
MeOH
ke
4-15
730
525
74-1
595
64-2
585
398
885
510
15f4
915
1610
1158
1633
1311
14-15
1510
1097
1950
1125
EtOH
*§ f
181 398
14-33 3160
318 700
220 484
0 0
446 983
0 0
300 661
0 0
694- 1530
IN 24
HOURS
HAc
4470
4657
4529
4666
5168
4050
4590
4186
4185
4063
4330
9855
10268
9984
10287
11394
8929
10129
9229
9226
8957
9547
Furf .
k£
701
420
497
335
410
393
337
528
181
591
195
#
1546
926
1096
739
904
866
743
1163
399
1304
430
SOp
kg ^
34 76
9
15
11
5
11
28
14
9
11
32
19
33
25
10
25
62
30
20
25
71
AVE. 7721 17021 10 22 631 1392 327 720 4445 9800 417 920 16 36
-------
TABLE 2A. % REMOVAL BY STEAM STRIPPER
% REMOVAL BY STEAM
DATE
Dec.
1977
9
10
12
13
14
16
17
19
20
21
22
BOD
' 41.7
47.2
30.3
55.1
35.0
49.8
42.0
38.7
25.4
49.6
40.8
MeAc
100
100
100
100
100
100
100
100
100
100
100
MeOH
85.2
100
100
100
100
100
100
100
100
100
100
EtOH
100
100
100
100
100
100
100
100
100
100
100
STRIPPER
HAc
23.1
35.3
31.3
20.8
32.0
44.7
66.9
55.1
42.8
72.0
51.5
Purr.
100
100
100
100
100
100
100
100
100
100
100
SOp
100
50
71.4
80.0
50.0
80.0
84.6
83-7
75.0
80.0
92.9
AVE.
40.2
100
98.8
100
42.4
100
84.1
-------
APPENDIX B.
HEAT AND MATERIAL BALANCES ABOUND THE FRACTIONATORS
The following tables show heat and material balances around
the major pieces of operating equipment and storage tanks used
in this process. Each stream is cross reference- by block flow-
sheet No. to figures 1, 2, and 5 of this report.
-------
rpART.TT TR TTEAnn ATJT) MATtf-RTAT, •RAT.AlSrntt JPOR ST^AM cjrppTpp-^R
BLOCK FLOWSHEET NO.,
See Fig. 1
FLOW BATE ke/s
#/hr
COMPONENTS
METHANOL Iss/a
#/hr
FURFUEAL ke/s
#/hr
ACETIC kp/s
ACID #/hr
SULFUR ke/s
DIOXIDE #/hr
ETHANOL ke/s
#/hr
ETHYL ke/s
ACETATE #/hr
METHYL kc/s
ACETATE #/hr
WATER ke/s
#/hr
PROPERTIES
TEMP. UC
UF
PRESS kPa
IDSIR
SPECIFIC GRAVITY
SPECIFIC HEAT
VISCOSITY CDS
HEAT QUANTITIES
kJ/kK
btu/#
19
Btms fm.
DESIGN
12.4
98,702
12.4
98.702
129
265
268.9
59
0.955
1.010
0.17
544
254
stri-DTEC
OPER.
7,12
56,500
0.0115
90
7.11
56.410
129
265
268.9
59
24
btms fm.#l frac.
DESIGN
2.96
25,500
2.96
25.500
100
212
586
85
0.958
1.007
0.26
418
180
OPER.
2.08
16,496
0.008
58
2.07
16,458
100
212
158
0.2
21
Disch. to T.P.
DESIGN
15.4
122.202
15.4
l?2t?02
69.4
157
227
55
0.977
1.004
0.42
291
125
Continue
OPER.
9.2
72.996
0.0161
128
9.1R
72 1 86ft
69.4
157
227
55
1
-------
TABLE 1B (CONTINUED)
BLOCK FLOWSHEET NO..
(See Fig. 1)
FLOW RATE kg/s
#/h-p
COMPONENTS
METHANOL kg/s
#/hr
FURFURAL kg/a
£/hr
ACETIC kg/R
ACID sSf/hr
SULFUR k.g/3
DIOXIDE #/h-r
ETHANOL ke/s
#/hT>
ETHYL kg/s
ACETATE 3^/h-r
METHYL kg/s
ACETATE #/h4
WATER kg/s
7^/h-r
PROPERTIES
TEMP. OC
°F
PRESS kPa
psig
RPECT1?TC TrRAVITY
RPEnTT?TH TTEAT
VTRCORTTY f.ps
HEAT QTTANTTfTTER .
k,T/kg
"htii/^
20
Steam
DESTCiN
5.15
25.000
3.15
25,000
134
274
207
30
0.092
0.46
0.0135
2726
1172
OPER.
2.27
18.000
2.27
18,000
134
274
207
30
0.092
0.46
0.0135
]<=>
Ffifid t;o heat; fixn.
DESIGN
12.3
97.323
0.015
120
0.030
240
12.25
97,203
54
130
269
39
0.986
1.000
0.55
228
98
OPER.
6.93
55 T 000
0.005
38
0.0001
1
0.018
139
0.0005
4
0.005
43
0.0001
1
6.90
54,774
54
130
269
39
16
Feed fm.heat; RTC.
J3ESIGN_j
12.3
97.323
0.015
120
0.030
240
12.25
97,203
121
250
159
23
0.942
1.010
0.20
507
218
OPER.
6.93
55.000
0.005
38
0.0001
1
0.018
139
0.0005
4
0.005
43
0.0001
1
6.90
54,774
121
250
, 172
25
17
overhead fm.stTO
DESIGN
2.98
23.621
0.015
120
0.030
240
2.96
23,501
121
250
159
23
0.072
0.460
0.013
2708
1164
OPER.
2.08
16 . 500
0.005
38
0.0001
1
0.005
38
0.0005
4
0.004
28
20
0.0001
1
2.06
16,370
127
260
193
28
-------
TABLE 2B HEAT AND MATERIAL BALANCE FOR #1 FRACTIONATOR
BLOCK FLOWSHEET NO.
See Fig. 1 '
TPinv PATTC Xg/f!
#/hr
noMPfyKiwTS
MWTOTATJnT, frg/-^
#/hr
MTP.FTTPAL fcg/s,
#/hr
AOETTC! Xg/s
AHTD ^/h-p
RTTT.mn? kg/fi
TTTOYTTm 3$Tg/f5
AH-RrpAT-R pSf/hT
UAT-RR l^g/p
^/hr
PRO PARTIES
T-RMP. °Q
OT?
pp"RSS xpa
psi g
SPWlTFTn TrP-AVITY
RPWITFTC FEAT
VTRfJORTTY nps
HEAT QTTANTTTTES
kJ/kg
btu/#
18
Ffied fm.
DESIGN
P.Q8
P^ fiPl
o.ms
IPO
0.030
P40
P.Q6P
P^tS01
116
P4-0
6Q
10
O.Q4R
"1 .011
O.PO
484
P08
strpr.
OPER.
P. 08
1 6 , SOO
O.OOS
38
0.0001
1
0.0048
38
0.0005
4
0.0035
P8
O.OOP5
PO
0.0001
1
P. 063
16 t 370
P5
77
0
0
41
Feed fm.,
DESIGN
0.085
677
0.0005
4
0.013
100
0.0089
71
0.063
502
40
104
7
1
0.958
0.894
0.688
149
64
^5 sen.
OPER.
0.019
150
3.0005
4
0.0006
5
0.0016
13
0.0001
1
0.016
127
25
77
24
Bottoms 5
DESIGN
2.96
23 . 500
2.961
23 . 500
100
212
586
85
0.958
1.007
0.26
419
180
01 frac.
OPER.
2.08
16.496
0.0048
38
2.074
16,458
100
212
1
0.2
23
Ovrhd. #r Frac.
DESIGN
0.015
121
0.015
120
0.030
240
0.0001
1
44
111
7
1.0
0.760
0.62
0.45
114
49
OPER.
0.019
154
0.0053
42
0.0001
1
0.0005
4
0.0042
33
0.0042
33
0.0003
2
0.0049
39
25
77
0
0
-------
TABLE 3B HEAT AND MATERIAL BALANCE FOR #2 FRACTIONATOR
BLOCK FLOWSHEET NO.
See Fig. 1
FLOW RATE ke/s
#/hr
COMPONENTS
METHANOL kp/s
#/hr
FURFURAL kp/s
#/hr
ACETIC kp/s
ACID #/hr
SULFUR kp/s
DIOXIDE #/hr
ETHANOL ke/s
#/hr
ETHYL kp/s
ACETATE #/hr
METHYL ke/s
ACETATE #/hr
WATER kff/s
#/hr
PROPERTIES
TEMP. °C
Uj,
PRESS kPa
psig
SPECIFIC GRAVITY
SPECIFIC HEAT
VISCOSITY CTDS
HEAT QUANTITIES
kJ/ks
btu/#
23
Feed to #2 Frac.
DESIGN
0.015
121
0.015
120
0.030
240
0.0001
1
44
111
7
1.0
0.760
0.6P
0.45
114
4Q
OPER.
0.019
154
0.0053
42
0.001
1
0.0005
4
0.0042
33
0.0042
33
0.0003
2
0.0049
39
25
77
0
0
25
Btms.fm.#2 frac.
DESIGN
0.0001
1
0.030
240
0.0001
1
100
212
152
22
0.958
1.007
0.26
419
1RO
OPER.
0.0092
73
0.001
1
0.0042
33
0.0049
39
81
178
2
0.3
26
Ovrhd.fra.#2 Frac.
DESIGN
0.015
120
0.015
120
44
111
'7
1.0
0.760
0.62
0.45
114
49
OPER.
0.0102
81
0.0053
42
0.0005
4
0.0042
33
0.0003
2
60
140
0
0
-------
•I*
VJI
TABLE 4B HEAT AND MATERIAL BALANCE FOR #5 FRACTIONATOR FEED TANK
BLOCK FLOWSHEET NO..
See Fig. 1
•RTDW RATE fcg/s
#/hr
coMPON'Risr'rs
METHANOT, fcg/s
#/hr
MTRFTTT?AT, feg/s
^7h-p
ACtfTTO kg/s
A.r.fn #/hr
STTLWTR kg/s
nTOYTTTE 5&7V1T
WPHATTOT, Irg/s
^/hr
WFHYT, Xg/s
AfJ-pyTATT? ^/hT
IVTRTHYT, kg/s
ftf! TCP ATE 3^/hT
UAT-RR Kg/R
3^/hT
PROPERTIES
T-RMP. °C!
Op
PRESS kPa
Dsic
SPECIFIC GRAVITY
SPECIFIC HEAT
VISCOSITY nps
HEAT QUANTITIES
KJ/lfg
t>tu/#
25
Btm. #2 Fract.
DESIGN
n nnni
1
0.0001
1
TOO
PI?
1S2
22
O.Q58
1.007
0.26
^-19
180
OPER.
n ODQ?
7^
0.0001
1
0.0042
tt
0.00^9
^9
81
178
2
0.5
51 Intermittent .
FnRe K . Le ve 1 Tank
DESIGN
n.^fi^i
4470
0.0005
4
0.0087
69
0.075
585
0.472
5748
60
140
117
17
0.985
1.006
0.49
251
108
OPER.
O.O4O
514
0.0006
5
0.0004
5
0.0101
80
0.0005
4
0.028
222
102
215
52 Intermittent
Fm.Regen. Cond.
DESIGN
D.P7?
2158
0.147
1168
0.109
862
0.016
128
58
100
76
11
0.846
0.610
0.744
95
41
OPER.
O.455
5615
0.0008
6
0.0065
50
0.0059
51
0.116
92
0.0055
42
0.0001
1
0.522
2558
40
104
41
Btm. #5 Separatoi
DESIGN
0.085
677
0.0005
4
0.0125
100
0.0089
71
0.065
502
40
104
7
1
0.958
0.894
0.688
149
64
OPER.
0.019
150
0.0005
4
0.0006
5
0.0016
15
0.0001
1
0.016
12?
25
77
-------
TABLE 4B (CONTINUED)
BLOCK FLOWSHEET NO.
See Fig. 1
FLOW RATE ke/s
#/hr
COMPONENTS
METHANOL ke/s
#/hr
FURFURAL ke/s
#/hr
ACETIC ke/s
ACID #/hr
SULFUR ke/s
DIOXIDE #/hr
ETHANOL ke/s
#/hr
ETHYL kg/3
ACETATE #/hT
METHYL ke/s
ACETATE ^/h-p
WATER ke/s
#/hr
PROPERTIES
TEMP. °C
bp
PRESS kPa
psie
SPECIFIC (GRAVITY
SPECIFIC HEAT
VISCOSITY CTDS
HEAT QUANTITIES
kJ/ke
btu/#
75 Intermittent
Fm. Educt. Cond.
DESIGN
0.0079
63
0.0024-
19
0.0055
44-
21
70
152
22
1.05
0.825
0.47
72
51
OPER.
-p
S
•^
a-
o
&
102 Intermittent
EtOH Fm.#7 Frac.
DESIGN
-p
A
t— \
bD
o
ft
o
&
OPER
fft
-p
vu
Q
pH
faD
^
o
^
o
&
101 Intermittent
Fm.Bot. #10 Frac
DESIGN
rrt
-P
0
rH
•Jj)
Q
fl
O
3
OPER.
rrf
-P
O
cl
hO
O
£
O
UH
81
178
5
0.4
33
Fm. #3 Feed T.
DESIGN
0.648
5139
0.0005
4
0.0087
69
0.068
683
0.0084
67
0.535
4247
60
140
179
26
0.983
1.006
0.49
251
108
OPER.
0.^04
4000
0.0008
6
0.0071
56
0.0043
34
0.131
1038
0.0058
46
0.0001
1
0.355
2819
-------
TABLE 5B HEAT AND MATERIAL BALANCE FOR #3 FRACTIONATOR
BLOCK FLOWSHEET NO..
See Fig. 1 •
FLOW RATE kp/a
#/hr
COMPONENTS
METHANOL kg/a
tf/hr
FURFURAL ke/s
72/h-p
ACETIC kK/s
ACID ti/h-r
STILFim kg/a.
DIOXIDE j&Th-p
ETHANOL k^/jji
#/hr
ETHYL ktf/s
ACETATE sK/h-p
METHYL k.g/s
ACETATE 7^/h-p
WATER lrg/s
^/hr
PROPERTIES
TEMP. °C
Oj,
PRESS kPa
psiff
SPECIFIC GRAVITY
SPECIFIC HEAT
VISCOSITY
HEAT QUANTITIES
kJ/kK
btu/#
33
Pm.#3Frac.Sts.T.
DESIGN
0.64R
S13Q
O.OOOS
4
O.OOR7
6Q
O.ORfi
fi«3
n.nn«4
67
0.535
4247
60
140
179
26
0.983
1.006
0.49
251
108
OPER.
0 . 504
4000
O.OOOR
6
0-0071
56
O.O043
34
0.131
1D3R
n.nn5R
46
0.0001
1
0.355
2819
54
130
35A *
Btms#3to#7Fract.
DESIGN
0.54R
435O
O.OOR7
6Q
0.531
4?1?
102
215
172
25
0.956
1.008
0.25
428
184
OPER.
O-PRR
?PR6
0.0057
4-5
O.O035
PR
o.nrxvi-
7,
O.P7R
P?10
100
212
35B *
Btms. to Suree T
DESIGN
n.^R
43 5D
n.onR7
fiQ
0.531
421 P
102
215
172
25
0.956
1.008
0.25
428
184
OPER.
O.nfiS
514
o.onm
1 1
0 OOOR
fi
0.063
497
too
PIP
34
Ovrhd to
DESIGN
n OQQ
7RQ
n nnn1^
a
n nRft
A«^
n rtCtfl.il
67
0 O044
35
49
IPO
7
1
0.808
0.730
0.760
149
64
£4 SteT,
OPER.
n i m
i pnn
n nnnft
A
n i^n
in^c;
n nnc;«
46'
O.O001
1
0 O141
1 IP
39
10P
0
0
*18% of the time bottoms go to surge tank.
-------
TABLE 6B HEAT AND NATERIAL BALANCE FOR #7 FRACTIONATOR
BLOCK FLOWSHEET NO.
See Fig. 1
FLOW RATE ke/s
#/hr
COMPONENTS
METHANOL ks/s
#/hr
FURFURAL ke/s
#/hr
ACETIC kp/s
ACID #/hr
SULFUR ke/s
DIOXIDE #/hr
ETHANOL kff/s
j#/hr
ETHYL ACE ke/s
ACETATE j07hr
METHYL ke/s
ACETATE #/hr
WATER ke/s
#/hr
PROPERTIES
TEMP. UC
OF
PRESS kPa
psxg
SPECIFIC GRAVITY
SPECIFIC HEAT
VISCOSITY cps
HEAT QUANTITIES
kJ/ks
btu/#
35A
#7 Frac.
DESIGN
0.54-8
4.550
0.0087
69
0.531
4212
102
215
172
25
0.956
1.008
0.25
428
184
Feed
OPER.
0.288
2.286
0.0057
45
0.0055
28
0.0004
3
0.278
2210
100
212
47
Dvrhd.fra.j
DESIGN
0.058
458
0.0150
105
0.045
555
40
104
7
1
1.056
0.867
147
65
^7 frac.
OPER.
0.019
151
0.0052
41
0.0018
14
0.012
96
39
102
49
Reflux fi
DESIGN
0.049
385
0 .-0045
54
0.044
551
40
104
7
1
1.014
0.948
158
68
n.day tk
OPER.
0.014
115
0.0010
8
0.0016
13
0.0118
94
39
102
71
90% Crud
DESIGN
0.0045
36
0.0042
33
0.0004
3
21
70
j furf.
OPER.
0.0045
36
0.0042
35
0.0001
1
0.0003
2
21
70
--
-------
TABLE 6B (CONTINUED)
BLOCK FLOWSHEET NO.
See Pig. 1
WmW RATTC kff/S
#/hr
qoMpmrarTs
METHANOL ke/s
#/hr
FURFURAL ke/s
#/hr
ACETIC ks/s
ACID #/hr
SULFUR ke/s
DIOXIDE #/hr
ETIIANOL kK/s
#/hr
ETHYL kK/s
ACETATE y//hr
METHYL ke/s
ACETATE #/hr
V/ATER ka/s
#/hr
PROPERTIES
TEMP. °C
op
PRESS kPa
psiec
SPECIFIC GRAVITY
SPECIFIC HEAT
VISCOSITY CTDS
LIEAT _QJJAHTITIES
kJ/kfs
btu/^
4fi
Btms.fm.#7 Frac.
DESIGN
0.559
4281
0.531
4216
100
212
124
18
0.852
1.008
0.262
421
181
OPER.
0.283
2250
0.0015
12
0.0035
28
0.0003
2
0.278
2208
100
212
1
0.2
-------
VJ1
o
TABLE 7B
HEAT AND MATERIAL BALANCE FOR #7 FRACT. 92 TO 98% FURFURAL PURITY
BLOCK FLOWSHEET NO.
See Fig. 5
FLOW RATE kg/R
^Ai-p
COMPONENTS
METHANOT, kg/s
^/hr>
TTTTRWTRAT, k.g/_s
3^/h-p
AC-RTTC Ve/s
AHTT) ^/h-p
RTTT.TPTTR Trg/s
•nTOYTTTR #/Trr>
EmATTOT, Ve/s
^/h-P
ETTTYT, kg/s
An-RfPATTR :#/h-r
MEWTYT, kg/s
An^rpAfT-R ^/irp
WATER kg /a
30/h-r
PROPERTJ-RS
TEMP. °C
UE
PRESS kPa
^ psig
SPECTFTn fi-RAVTTY
SPECTETO FEAT
VTSOOSTTY nps
HEAT1 QTTANTTTTES
k.T/kg
^W#
71
Crude 1
DESIGN '
.O04S
^6
n . DO4P
^^
-OO04
5)
?1
7°
\irfural
OPER.
.004S
^6
O.O04?
^^
.nnm
i
.nnn';
?
?i
70
82
Ref:
DESIGN
90-9R°/6
Tax
OPER.
QO-Qfi^
83
To I
DESIGN
•
Day Tank
OPER
-------
VJ1
TABLE 9B HEAT AND MATERIAL BALANCE FOR #4 FEED TANK
3LOCK FLOWSHEET NO.
See Fig. 2
FLOW RATE ke/s
#/hr
COMPONENTS
METHANOL ke/s
#/hr
FURFURAL kpr/s
#/hr
ACETIC ke/s
ACID #/hr
SULFUR ke/s
DIOXIDE #/hr
ETHANOL ke/s
#/hr
ETHYL ke/s
ACETATE #/hr
METHYL" ke/s
ACETATE #/hr
WATER ke/s
#/hr
PROPERTIES
TEMP. UC
Up
PRESS kPa
PSIK
SPECIFIC GRAVITY
SPECIFIC HEAT
VISCOSITY cps
HEAT QUANTITIES
kJ/kK
btu/#
34
Ovhd.fm.#3 Frac.
DESIGN
0.099
789
0.0005
4
0.086
683
0.0084
67
0.0044
35
49
120
7
1
0.0808
0.730
0.760
149
64
OPER.
0.151
1200
0.0008
6
0.130
1035
0.0058
46
0.0001
1
0.014
112
39
102
0
0
104
Ovhd.fm.#10Frac.
DESIGN
0.108
858
0.108
858
77
170
117
17
0.900
0.474
0.272
151
65
OPER.
0.0038
30
0.0038
30
77
170
0
0
36
To #5 Frac. Feed
DESIGN
0.371
2947
0.0005
4
0.233
1851
0.117
929
0.021
163
38
100
152
22
0.836
0.599
0.719
95
41
OPER.
0.151
1200
0.0008
6
0.130
1035
0.0058
46
0.0001
1
0.014
112
21
70
-------
ro
TABLE 10B HEAT AND MATERIAL BALANCE FOR #5 FRACTIONATOR
BLOCK FLOWSHEET NO.
See Fig. 2
FLOW RATE kg/a
a/hr
COMPONENTS
METHANOL kg /a
jg/h-r
FURFURAL kg/s
#/hT-
ACETIC kg/s
ACID ^/h-r
SULFUR kg/s
DIOXIDE T^/hr
ETHATTOL kg/s
j&E/h-r
ETHYL ke;/?
ACETATE -"/hT.
METHYL kg/a
ACETATE #/hr
WATER k.g/R
PROPERTIES
TEMP. UC
UF
PBESS kPa ,_
-*. PR1'g
SPECIFIC CrPAVITY
SPECIFIC HEAT
VISCOSITY cpa
HEAT OTTANTTTIES
kJ/kg
btu/^
^6
^5 Frac
DESIGN
0.371
pq/4-7
n.ooos
4
0.233
18S1
0.117
Q2Q
O.OP1
163
38
100
152
PP
0.836
O.S9Q
0.719
95
41
Feed
OPER.
0.151
1POO
0.0008
6
0.130
1O35
0.0058
46
0.0001
1
O.O14
IIP
PI
70
39
3tms.fm.^
DESIGN
O.P*n
18P5
O.P21
1751
0.0093
74
78
173
15P
PP
0.766
0.846
0.48?
277
119
J5 Frafi.
OPER.
^.143
1138
0.1P9
10P5
0.0004
3
0.014
no
79
175
3
0.4
40
Qvhd . f m
DESIGN
0 - 1 41
1122
0.0005
4
0.0126
TOO
•0.117
9P9
0.0112
89
54
130
' 7
1
0.899
0.532
0.382
121
52
#5 Frac.
OPER.
0.0078
62
0-0005
4
0.0006
5
0.0054
43
0-0001
1
0-0011
9
61
141
0
0
-------
TABLE 10B (CONTINUED)
•RTDHF •RTfiURHEET NO.
See Fig. 2
WDW RATE frg/fi
#/hr
COMPONENTS
MWFFTAWnT, fcg/s
#/h-p
FTTRMTRAT, Kg/s
^/h-r
ACT/PIC kg/a
A HIT) #/h-p
STTLWTR kg/s
DTOYTDE #/hr
ETFTANOT, fcg/s
tf/hr
ETRYT, kg/s
AO"RTATE #/lrr«
MWFTYT, kg/fi
AnWTA.TE ^/h-p
WATER kg/s
#/hr
PROPERTIES
TEMP. U0
UT?
PRESS kPa
PSiK
SPECIPTC GRAVITY
SPECIFIC HEAT
VISCOSITY
HEAT QUANTITIES
KJ/kg
btu/#
Ztl
Btms . f BL
DESIGN
0.08S
fV77
O.OOOS
4-
...
O.01P6
TOO
O.OORQ
71
0.06^
SOP
40
104
7
1
0.958
0.894
0.688
149
64
. separ.
OPER.
0.019
ISO
0-0005
4
0.0006
5
0.0016
13
0.001
1
0.016
i?7
25
77
4?
Feed to ^
DESIGN
0.449
3565
0.0089
71
0.418
3315
0.023
179
40
104
7
1
0.903
0.494
0.405
84
36
£ frac.
OPER.
0.015
117
0.0001
1
0.0004
3
0.014
108
0.001
1
0.0005
4
21
70
45
Btms. fm #6Frac.
DESIGN
0.108
858
0.018
858
77
170
117
17
0.900
0.474
0.272
151
65
OPER.
0.0038
30
0.0038
30
77
170
1
0.2
43
Ovhd.fm.jj
DESIGN
0.341
2707
0.0089
71
0.310
0.023
179
40
104
7
1
0.904
0.503
0.413
84
36
6 Frac.
OPER.
0.0110
87
0.001
1
0.0004
3
0.0098
78
0.0001
1
0.0005
4
24
75
0
0
0.503
-------
Table 11B HEAT AND MATERIAL BALANCE IDE EtAc SEPARATOR & NO. 6 FRACTIONATOR
BLOCK FLOWSHEET NO..
See Fig. 2
FLOW RATE ker/s
#7hT
COMPONENTS
METHANOL ke/s
^/h-r
FURFURAL kg/p
#7hr
ACETIC kg/s
A.CTD #/h-r
SULFUR kg/s
DIOXIDE 5^/h-p
ETHA1TOL kg/a
#/hr>
ETHYL kg/fi
ACETATE ^/h-p
METHYL kg/a
ACETATE ^/h-r
WATER kg/R
^7hr
PROPERTIES
TEMP UC
Oj>
PRESS kPa
p,sier
SPECIFIC GRAVITY
SPECIFIC HEAT
VISCOSITY CBS
HEAT QUANTITIES
kJ/ke
btu/#
40
Ovhd.fm. #5 Frac
DESIGN
0.141
11?2
0.0005
4
0.01P6
100
0.117
Q?Q
0.011P
sq
7?
1^0
7
1
0.899
0.552
0.582
121
52
OPER.
62
0.0005
4
0.0006
5
0.0054
45
0.0001
1
0.0011
9
61
141
0
0
44
Water
DESIGN
0.052
415
0.052
415
82
180
7
1
0.999
1.000
1.100
544
148
OPER.
0.015
117
0.015
117
21
70
43
Ovhd.fm.^
DESIGN
0.541
2707
0.0089
71
0.510
2457
0.025
179
40
104
7
1
0.904
0.505
0.415
84
56
?6 Frac.
OPER.
0.0110
87
•
0.0001
1
0.0004
5
0.0098
78
0.0001
1
0.0005
4
24
75
0
0
42
Ovhd. fm
DESIGN
0.449
5565
0.0089
71
0.422
5515
0.025
179
40
104
7
1
0.905
0.494
0.405
84
56
Senar
OPER.
0.015
117
0.0001
1
0.0004
5
0.014
108
0.0001
1
0.0005
4
21
70
-------
VJ1
VJJ
TABLE 12B HEAT AND MATERIAL BALANCE FOR #10 FRACTIONATOR
BLOCK FLOWSHEET NO.
See Fig. 2
FLOW RATE ker/s
#/hr
COMPONENTS
METHANOL ke/s
#/hr
FURFURAL ke/s
£/hr
ACETIC ktf/s
ACID #/hr
SULFUR k.g/S
DIOXIDE #/hr
ETHANOL ker/s
#7hr
ETHYL ke;/s
ACETATE #/hr
METHYL k^/s
ACETATE #/hr
WATER te/s
#/hr
PROPERTIES
TEMP. °C
UF
PRESS KPa
psig
SPECIFIC GRAVITY
SPECIFIC HEAT
VISCOSITY ops
HEAT QUANTITIES
kjAg
btu/#
^-S
Feed ia^lOFrac.
DESIGN
0.108
8S8
0.108
858
79
170
117
17
O.QOO
0.474
0.27?
1ST
65
OPER.
0.0038
30
0.0038
30
77
170
1
0.?
101
Btm.fn.#10 Frac.
DESIGN
erf
-p
erf
Q
.£
W
r-J
o
d
1 -i
o
f^H
OPER.
erf
-P
erf
p
_£H
r-<
O
&
I "\
O
f^t
104
EtAc Prod.
DESIGN
0-10&
858
O.TOft
858
77
170
117
17
o.qoo
0.474
0.272
151
65
OPER.
0.0038
30
0.0038
30
77
170
i
o.?
-------
TABLE 8B
HEAT AND MATERIAL BALANCE FOR #7 FRACT. 98 TO 99.6% FURF. PURITY
BLOCK FLOWSHEET NO.
See Fig. 5
FLOW RATE kp;/s
#/hr
COMPONENTS
METHANOL ke/p
#/hr
FURFURAL ker/s
#/hr
ACETIC ks/s
ACID #/hr
SULFUR ker/s
DIOXIDE #/hr
ETHANOL kc/s
#/hr
ETHYL hpj/p
ACETATE #7hr
METHYL kp;/s
ACETATE ^7hr
WATER ke/s
7^/hr
PROPERTIES
TEMP. UC
WF
PRESS kPa
psie
SPECIFIC GRAVITY
SPECIFIC HEAT
VISCOSITY CDS
HEAT QUANTITIES
71A
Kettle
DESIGN
98%
OPER.
98%
105
To Dav Tank
DESIGN
98%+
OPER.
98%+
50
Product
DESIGN
•
OPER
0.0037
29
0.0037
29
40
104-
-------
APPENDIX C
ABSTRACTS FROM PERTINENT PATENTS
UNITED STATES PATENT 4,002,525 Baierl January 11, 1977
Chemical Recovery From Waste Liquors Utilizing Indirect Heat
Exchangers in Multi-Stage Evaporation Plus Contact Steam
Stripping.
A method of treating was-te liquors such as those derived
from the sulfite or Kraft pulp making process is disclosed
which provides recovered "by-products of high purity while
moreover decreasing the total amount of process steam required.
The method comprises steam stripping the evaporator condensate
feed to remove volatile chemical by-products therefrom, and
thereafter directing the stripping steam for reuse in concen-
trating additional volumes of feed in the evaporator. In this
manner, the only steam lost during the stripping operation is
that used for increasing the sensible heat of the evaporator
condensate feed within the steam stripping column. The con-
densed steam and volatile by-products resulting from evaporator
heating operation are then preferable directed to a fraction-
ation column or columns in order to separate and recover the
valuable by-products for reuse or sale. In situations where
the condensate feed contains volatile noncondensible gases
which are valuable for reuse, the evaporator condensate feed
may be preheated and contacted with evaporator vent gases. The
latter are partially condensed to allow the noncondensible
gases to be recovered and reused.
UNITED STATES PATENT 4,016,180 Baierl April 5, 1977
Chemical Concentration by Adsorption
A low cost, two-stage adsorption-desorption method of
concentrating dilute supplies of chemicals is provided which
uses a minimum of energy in the form of process steam and
yields highly concentrated supplies of end products which are
suitable for reuse or sale. The methods hereof are particular-
ly adapted for concentrating waste condensates derived from
pulp-making operations such as the Kraft or Sulfite processes,
but in general is also applicable for treating all types
57
-------
of dilute organic or inorganic adsorbable chemicals. The
invention involves first adsorbing a chemical fraction from a
dilute stream thereof onto activated carbon, followed by-
regenerating the adsorbed chemicals and concentrating the
same by fractional distillation, whereupon the partially con-
centrated chemicals are again adsorbed, regenerated, subjected
to a second fractional distillation concentration step, and
recovered. In preferred alternate procedures, aqueous sulfite
waste condensates containing minor amounts of acetic acid,
methanol, furfural and sulfur dioxide are treated by the
methods hereof to yield concentrated quantities of acetic
acid, ethyl acetate or furfural.
UNITED STATES PATENT 4,071,398 Baierl January 31, 1978
Chemical Concentration by Sequential Activated Carbon
Adsorption and Fractionation.
A continuous, low cost method of concentrating dilute
streams containing fractions of adsorbable chemicals is dis-
closed which minimizes heat consumption and provides highly
concentrated supplies of valuable chemicals which are suitable
for reuse or sale without substantial further processing. The
methods hereof are particularly adapted for concentrating
waste condensates derived from pulp-making operations such as
the Kraft or sulfite processes, but in general are also
applicable for treating a wide variety of dilute organic or
inorganic adsorbable chemicals. The invention involves
initially adsorbing and concentrating a chemical fraction from
the dilute stream followed by desorption and recycling of the
adsorbed materials to further concentrate the same, whereupon
the desorbed chemicals are directed to a second concentration
zone and concentrated therein; at this point the partially
concentrated stream is diverted back to the adsorption zone
for further adsorption and concentration simultaneously with
the dilute stream initially passing there through while con-
centration continues in the second zone to yield a final
product having a concentration on the order of 90% by weight
or better.- In preferred forms only a single fractionating
column is employed in the second concentration stage which
minimizes capital costs and reduces steam consumption, while
recycling back to the adsorption zone permits continuous
operation of one fractionation column doing the work of two
or more columns. Thus, dual use of the single frae%ionator
column in both intermediate and final concentration steps
allows continuous operations with equipment heretofore used
only in batch-type operations.
-------
APPENDIX D
EQUIPMENT SPECIFICATIONS
The equipment used in the chemical recovery system were
sized as follows.
The vent tank is 1.2 m (4 ft.) in diameter and is 2.0 m
(6 ft. 8 in.) high. There is no packing in this unit. The
precondenser is 0.6 m (2 ft.) in diameter and 5 m (16}£ ft.)
high. It has 2,696,254 kJ/s (9,200,000 BTU/hr) capacity. The
vent condenser is 0.34- m (14 in.) in diameter and 3.2 m (10>i ft)
high and has 1.172,000 kJ/s (5,000,000 BTU/hr) capacity.
The steam stripper is 1.7 m (51/£ ft.) in diameter and 5-2 m
(17 ft.) high. It contains 0.91 m (3 ft.) of packing with 7
theoretical plates. The pressure drop through the packing is
5.17 Pa/m packing (0.75 inches of water/foot of packing). The
heat exchanger which heats the condensate to the steam stripper
is rated at 3-956,460 KJ/s (13,500,000 BTU/hr).
Each carbon tower is 2.7 m (9 ft.) in diameter and 18.3 m
(60 ft.) high. It contains 36,000 kg (40 tons) of carbon and
will hold 77.6 m5 (20,500 gal.) of liquid. The surge tank is
3.7 m (12 ft.) in diameter and 9.4 m (31 ft.) high. It will
hold 99-2 m3 (26,200 gal.) of condensate.
Number 1 fractionator is 0.91 m (3 ft.) in diameter and
7-1 m (23 ft. 2 in.) high. The stripping section has 2.7 ni
(9 ft.) of packing or 7 theoretical plates. It has a pressure
drop of 7.18 Pa/m (0.88 inches of water per foot) of packing.
The rectification section has 1.8 m (6 ft.) of packing or 7
theoretical plates. It has a pressure drop of 7-84 Pa/m
(0.96 inches of water per foot) of packing. The condenser for
this column is 0.56 m ^22 in.) in diameter with 8.8 m (8 ft.)
of tubing. It is rated at 1,361,901 kJ/s (4,647,000 BTU/hr.).
The reboiler for this fractionator is rated at 1.145,615 kJ/s
(3,909,000 BTU/hr).
Number 2 fractionator is 0.51 m (20 in.) in diameter and
8.8 m (29 ft.) in height. The stripping section has 4.5 m
(15 ft.) of packing or 24 theoretical plates. The pressure
drop through the packing is 20.41 Pa/m (2.5 inches of water
per foot) of packing. The rectification section has 2.1 m
59
-------
(7 ft.) of packing or 14 theoretical plates. It has a pressure
drop of 23.59 Pa/m (2.89 inches of water per foot) of packing.
The condenser for this column is .273 m (10-3/4 in.) in diameter
and has tubes 1.8 m (6 ft.) long. It is rated at 198,116 kJ/s
(676,000 BTU/hr.). The reboiler is rated at 200,460 kJ/s
(684,000 BTU/hr.).
Number 3 fractionator is 0.61 m (2 ft.) in diameter and
9.3 m (301/£ ft.) high. The stripping section contains 3-0 m
(10 ft.) of packing or Y^% theoretical plates. The pressure
drop through the packing is 3-51 Pa/m (0.43 inches of water
per foot) of packing. The rectification section contains
2.4 m (8 ft.) of packing or 13 theoretical plates. The pressure
drop through this packing is 8.90 Pa/m (1.09 inches of water
per ft.) of packing. The condenser for this column is .35 &
(14 in.) in diameter and the tubes are 2.4 m (8 ft.) long. It
has a rated capacity of 477,120 kJ/s (1,628,000 BTU/hr.). The
reboiler is rated at 494,997 KJ/s (1,689,000 BTU/hr.). The
feed tank for this unit is 3-4 m (11 ft.) in diameter and 5-5 m
(18 ft.) high. It will hold 48 m (12,800 gal.) of feed.
Number 7 fractionator is .30 m (1 ft.) in diameter and
4.16 m (13 ft. 8 in.) high. The stripping section has 1.8 m
(6 ft.) of packing or 10 theoretical plates. The pressure drop
through this packing is 5-71 Pa/m (0.7 in. of water per foot)
of packing. The rectification section has 1.2 m (4 ft.) of
packing or 9 theoretical plates. It has a pressure drop of
1.63 Pa/m (0.2 in. of water per foot) of packing. The con-
denser for this column is .22 m (8-5»8 in.) in diameter and
has tubes 1.2 m (4 ft.) long. It is rated at 143,312 KJ/s
(408,000 BTU/hr.). The reboiler is rated at 143,312 kJ/s
(489,000 BTU/hr.). ,The furfural day tank is 1..1 m (31/2 ft.)
in diameter and 1.8 m (6 ft.) high. It will hold 1.65 DK
(436 gallons).
Number 5 fractionator is .61 m (2 ft.) in diameter and
7.21 m (23 ft. 8 in.) high. The stripping section has 2.29 m
(71/£ ft.) of packing or 12 theoretical plates. The pressure
drop through this packing is 5-71 Pa/m (0.7 in. of water per
foot) of packing. The rectification section has 2.7 m (9 ft.)
of packing or 16 theoretical plates. The pressure drop through
this packing is 7»18 Pa/m (0.88 in. of water per foot) of
packing. The condenser for this column is .323 m (12-3/4 in.)
in diameter and has tubes of 2.44 m (8 ft.) long. It has a
rated capacity of 317,982 kJ/s (1,085,000 BTU/hr.). The re-
boiler for this column has a rated capacity of 326,774 kJ/s
(1,115,000 BTU/hr.
The #5 separator is .61 m (2 ft.) in diameter and 1.98 m
ft.) tall. It has no packing.
60
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Number 6 fractionator is .91 m (3 ft.) in diameter and
5.5 m (18 ft. ) high. The stripping section has 2.4 m (8 ft.)
of packing or 8 theoretical plates. The pressure drop through
this packing is 8.74- Pa/m (1.07 in. of water per foot; of
packing. The rectification section has .91 m (3 ft.) of pack-
ing or 2 theoretical plates. The pressure drop through this
packing is 5-71 Pa/m (0.7 in. of water per foot) of packing.
The condenser for this column is .41 in (16 in) in diameter
with tubes 2.4 m (8 ft.) long. It is rated at 617,793 kJ/s
(2,108,000 BTU/hr.). The reboiler for this column is rated at
545,112 kJ/s (1,860,000 BTU/hr.).
Number 10 fractionator is .30 m (1 ft.) in diameter and
7.6 m (25 ft.) high. The stripping section has 2.1 m (7 ft.)
of packing or 13 theoretical plates. The rectification section
has 2.1 m (7 ft.) of packing or 16 theoretical plates. The
condenser for this column is .168 m (6-5/8 in.) in diameter
with 2.4 m ( 8 ft.) tubes. This condenser is rated at 79,129
kJ/s (270,000 BTU/hr.). The reboiler is rated at 118,107
(403,000 BTU/hr.).
61
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GLOSSARY
bottoms: The discharge from the bottom of a fractionator or
steam stripper.
overhead: The discharge from the top of a fractionator or
steam stripper.
rectification section: The section above the feed plate of a
fractionator.
stripper: A steam stripping unit.
stripping section: The section below the feed plate in a
fractionator.
62
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TECHNICAL REPORT DATA
(Please read Instructions on the reverse before completing)
1. REPORT NO.
EPA-600/2-79-207
3. RECIPIENT'S ACCESSION NO.
4. TITLE AND SUBTITLE
VOLATILE COMPONENT RECOVERY FROM SULFITE
EVAPORATOR CONDENSATE
5. REPORT DATE
December 1979 issuing date
6. PERFORMING ORGANIZATION CODE
7. AUTHOR(S)
Walter A. Sherman, William A. Dryer, and John D. Michna
8. PERFORMING ORGANIZATION REPORT NO,
9. PERFORMING ORGANIZATION NAME AND ADDRESS
Flambeau Paper Co.
200 First Avenue North
Park Falls, Wisconsin 5^552
10. PROGRAM ELEMENT NO.
1BB610;01-05
11. CONTRACT/GRANT NO.
8-803302-01-0
12. SPONSORING AGENCY NAME AND ADDRESS
Industrial Environmental Research Laboratory
Office of Research and Development
U.S. Environmental Protection Agency
Cincinnati, Ohio ^5268
13. TYPE OF REPORT AND PERIOD COVERED
- 5/1 V?8
14. SPONSORING AGENCY CODE
EPA/600/12
15. SUPPLEMENTARY NOTES
16. ABSTRACT
This study is on the operation and modification of a demonstration unit to remove
sulfur dioxide, methanol, furfural and acetic acid from its sulfite evaporator con-
densate. This unit consisted of a steam stripper, vent tank S0_ recovery, activated
carbon adsorption columns and fractional distillation columns.
The steam stripping and fractional distillation of the stripped material parts
operate very successfully with little maintenance being required. In an extended
test run, the stripping process removed 8*f.1$ of the S0_, 100$ of the furfural, and
95.5$ of the methanol from the condensate at a steam rare of 2.8$ or 2?.7 Ibs. of
steam/1000 Ibs. of condensate stripped. The S0_ is separated, cooled, and returned
to the sulfite cooking acid make up system. Furfural is recovered at 90$ purity
which can be sold as crude, but Flambeau purifies it to 99.5$. Methanol is recovered
with less than 1$ water and is suitable for burning or some industrial uses. The
stripping Bt.eam is also used to heat the first effect of the multi-effect evaporator.
Activated carbon adsorption and ethyl alcohol regeneration of the carbon removes
acetic acid from the condensate and recovers it as ethyl acetate, which upon concen-
tration by fractional distillation is 99.5+$ pure. This part of the process is still
in the development stage.
17.
KEY WORDS AND DOCUMENT ANALYSIS
DESCRIPTORS
b.lDENTIFIERS/OPEN ENDED TERMS C. COSATI Field/Group
Evaporators, Condensation, Activated Carbon
Adsorption, Sulfite pulping, Spent sulfite
liquors, Paper industry, Biochemical oxygen
demand
Steam stripping
Fractional distilla-
tion
13B
18. DISTRIBUTION STATEMENT
RELEASE TO PUBLIC
19. SECURITY CLASS (ThisReport)
UNCLASSIFIED
21. NO. OF PAGES
73
20. SECURITY CLASS (Thispage)
UNCLASSIFIED
22. PRICE
EPA Form 2220-1 (Rev. 4-77) PREVIOUS EDITION is OBSOLETE
63
0 U.S. GOVEJWMEN1 PBINTINC OFFICE I9M-657-146/5523
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