PHASE II REPORT
APPLICABILITY OF ORGANIC SOLIDS TO THE
DEVELOPMENT OF NEW TECHNIQUES FOR REMOVING
OXIDES OF SULFUR FROM FLUE GASES
10669-6003-RO-OO 1 September, 1969
PREPARED FOR:
NATIONAL CENTER FOR AIR POLLUTION CONTROL
UNDER CONTRACT NO. PH22-68-46
TRW
ONE SPACE PARK
REDONDO BEACH, CALIFORNIA
-------
TRW
INTEROFFICE CORRESPONDENCE 4741.4.69-103
T° Distribution «=c: DATE: 3 October 1969
SUBJECT. Transmittal of TRW Document FROM: R. A. MeyersV
NO. 10669-6009-RO-OO BLDG. MAIL STA. EXT.
01 2161 69181
Transmitted herewith for your information and retention is a
copy of TRW Document No. 10669-6009-RO-OO, "Phase II Report
Applicability of Organic Solids to the Development of New
Techniques for Removing Oxides of Sulfur From Flue Gases",
dated 1 September 1969.
Distribution:
E. A. Burns
D. H. Cortez
A. F. Diaz
B. Dubrow
M. P. Gardner
E. D. Guth
A. Grunt
J. S. Land
A. A. Lee
J. L. Lewis
G. J. Ogle
M. K. O'Rell
R. S. Ottinger
C. Shih
J. R. Spraul
L. J. Van Nice
E. R. Wilson
SYSTEMS 0180 REV. 3-67
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1.- - - ~
I.
I
PHASE II REPORT
APPLICABILITY OF ORGANIC SOLIDS TO THE DEVELOPMENT
OF
NEW TECHNIQUES FOR REMOVING OXIDES OF SULFUR FROM FLUE GASES
by
R. A. Meyers, A. Grunt and M. Gardner
Prepared for:
National Air Pollution Control Administration
Under Contract No. PH 22-68-46
1 September 1969
Approved:
fa.~
.E. A. Burns, Manager
Chemical Research and
Services Department
TRIM
snnAlS GIfOUI' .
TRW SYSTEMS GROUP
One Space Park
Redondo Beach, California 90278
-------
1.0
INTRODUCTION AND SUMMARY
This Phase II addendum report describes the laboratory work performed
by TRW Systems Group for the National Air Pollution Control Administration
under Contract No. PH-22-68-46. The laboratory effort had the following
objectives:
.
Screen selected organic solids for ability
to remove sulfur dioxide from synthetic
flue gas, and
.
Obtain more detailed data on the most promising
organic solid (5)
As a result of a detailed literature search and conceptual analysis
during Phase I of this program, a number of organic solids were identified
as having capacity for the binding of sulfur dioxide. A principle accomplish-
ment of this task was the identification of a number of waste materials which
have high potential for removal of sulfur dioxide from flue gases. Organic
materia.ls were selected on the basis of:
.
Known or postulated ability to take up sulfur
dioxide,
.
Price and availability,
.
Thermal stability,
Regenerability, and
.
.
Mechanical properties.
Five organic materials were selected which offer promise for removing
sulfur dioxide from flue gases:
1.
2.
Ce 11 u 1 os i cs ,
Nigrosin~
3.
4.
Poly(N-vinylcarbazole) ,
Pyrolyzed poly(vinylchloride), and
5.
pyro lyzed poly( acryl onitri 1 e)..
-1-
-------
. -- - -~~~ ~ ~~--~ ---~-~----- .
The specific cellulosics selected were: waste newsprint, sawdust and
cotton. Although a number of other inexpensive cellulosic based materials
could have been evaluated, the limitations of Phase II required that the
scope be narrowed.
As little or no data was available regarding the ability of the above-
mentioned organic solids to sorb sulfur dioxide, a screening program was
initiated for the assessment of the relative potential of the selected or-
ganic solids for the removal of sulfur dioxide from flue gases. The screen-
ing program involved determination of thermal stability at flue gas temperature
(215°F and above) and ability to take up sulfur dioxide from moving flue gas
streams at 215° to 300°F. All seven candidates (this includes the three
cellulosics) were. found to be thermally stable in flue gas, while all but
nigrosin were found to take up substantial amounts of sulfur dioxide from
synthetic flue gas streams. Of the solids which were evaluated, newsprint
was found to be the most promising offering the following advantages over
other sorbent systems for removal of sulfur dioxide:
i
.
Selective sorption of sulfur dioxide from flue gas
streams. (Little or no pickup of nitrogen, water
carbon dioxide, oxygen, etc.).
Low initial price (e.g., $3.00 per ton for office
waste paper).
.
.
The large scale use of waste cellulosics for sulfur
dioxide removal could help solve a solid waste dis-
posal problem.
.
Ready availability of sorbent in areas proximate to
power stations.
Low attrition of sorbent (high mechanical strength.
e.g., tensile strength of 80,000 psi compared with
65,000 psi for medium steel).
.
.
Totally reversible sorption.
Low temperature regeneration (350°F).
.
-2-
-------
More detailed accumulation of data was performed on newsprint utili-
zing synthetic flue gases at temperatures encountered in flue gas streams
(2150 -3000F). 80th thermogravimetric analysis of weight increases of
newsprint as a function of time in synthetic flue gas and chemical analysis
of flue gas streams which had passed through packed beds of newsprint were
performed to determine rate and capacity of newsprint for S02 sorption. In
addition, regeneration studies were performed utilizing chemical analysis
of desorption streams. The results may be summarized as follows:
.
Newsprint picks up approximately 1-2% by weight sulfur
dioxide in 20 minutes at a flow rate of ca., 200 vol/hr.
Newsprint has a capacity of approximately 10% S02 by
weight.
.
.
Desorption streams of 16-26% by volume sulfur dioxide
are o~tained from newsprint at desorption temperatures
of 350-4500F.
The resu1t~ of the screening tests and more detailed accumulation of
data, together with experimental procedures are presented in four sections:
2.0
3.0
4.0
5.0
Screening of Organic Solids,
More Detailed Accumulation of Data on Newsprint,
Appendix A - Thermogravimetric Analysis of S02 Sorption and
Appendix 8 - Sorption-Desorption Experiments - Analysis of
Effluent Flue Gas
-3-
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10669-6009-RO-00
2.0
SCREENING OF ORGANIC SOLIDS
Five organic solids were identified in a detailed literature search
and conceptual analysis which offered promise for removing sulfur dioxide
from flue gas streams:
.
Cellulosics
.
Nigrosin
.
Po1y(N-viny1~arbazo1e) - PVK
Pyro1yzed po1y(viny1ch1oride) - PVC
.
.
Pyro1~zed poly(acrylonitrile) - PAN
The specific cellulosics selected for this study were: waste news-
print, sawdust, and cotton. The chemical compositions of the above candi-
dates as w~ll as the postulated chemical and physical interactions with
S02 are discussed in detail in the Phase I report. A sequential screening
program was designed in order to determine which of the candidates should
undergo more detailed characterization (Figure 1).
.
Thermal Stability
by Temperature
Programmed Thermo-
gravimetric Analysis
...
.....
Select Most
Promising
S02 Sorption at
~ i215°F by Is?therma1 ~
..... i ThermograVlmetric
Analysis
...
,
.. Sel ect Most
Promising
...
~.
S02 Sorption at
Three Temperatures
(215-300°F)
~
~
Selection for
,More Detailed
: Accumulation
i of Data
FIGURE 1. SCREENING OF ORGANIC SOLIDS
-4-
-------
Thermogravimetric analyses in air and in synthetic flue gas were identi-
cal (Figure 2) and showed that all of the candidates were stable at flue gas
temperatures. Two types each of pyrolyzed PVC and Nigrosin were evaluated.
The next sequential screening step involved measurement of weight uptake
by temperature programmed thermogravimetric analysis in a synthetic flue gas.
The flow rate was constant at 100 cc/min and it was assumed that weight up-
take was due to sulfur dioxide (this was verified for newsprint and sawdust).
All candidates were initially screened at 215°F. Poly{vinylcarbazole), saw-
dust, pyrol~zed poly{acrylonitrile), and newsprint picked up significant quan-
tities of sulfur dioxide (Table 1). At this point, those organic solids which
failed to pick up weight were eliminated (with the exception of cotton, as the
cellulosics as a class had shown weight uptake to 215°F and it was thought
possible that the cotton might show an improved weight uptake at elevated
temperatures). In addition, pOly{vinylcarbazole) was eliminated even though
it took up sulfur dioxide because of its high price, e.g., in order for the
PVK to be a candidate for further investigation, it would have had to show a
marked improvement over the other far less expensive organic solids.
The next screening step involved determination of sulfur dioxide uptake
at four temperatures (Table 2). Cotton, newsprint, sawdust, and pyrolyzed
- PAN picked up weight at temperatures of 2l5-300°F. The cellulosics did not
pick up weight in some of the temperature regions, probably due to the opera-
bility of more than one sorption mechanism (Eqs. 1 and 2). Table 3 shows the
regenerable uptake of S02 by newsprint and sawdust as compared with activated
charcoal.
CHARGE TRANSFER
..
CELLULOSE + n S02 ... .. CELLULOSE. (502)n
K . =. [CELLULOSE. (502)n1 n .
equtl [ CELLULOSE I [S02 I n
~!
\'1'
(1)
CHEMICAL REACTION
CELLULOSE -f OH)n +nS02 ... ~ CELLULOSEf OS02H)n
K = [CELL:ULOSE-f OS02H)nJ n
equil (CELLUL05Ef OH)nJ. I 502J n
(2)
-5-
-------
o
10
20
:10
~«)
S
;: 50
I ~
0\ i to
I
10
10
to
100
0
I
J2
~
. N!WS"INT~,
I
I
I
I
I
I
,
\
,
,
"
~
.
COAnNGS ON Fm.ICK
soo
I
212
I
m
\ I
m
I
752
I
752
I
212
I
m
I
J2
. I
J92
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I
J92
I
:J92
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212
I
932
I
12
. I
:192
I
572
I
752
I
932
FIGURE 2.
Thermogravimetr1c Analyses of Organic
Solids in Air or in Synthetic Flue Gas
.....
o
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-------
10669-6009-RO-00
TABLE 1
S02 SORPTION AT 2150F OF ORGANIC SOLIDS BY ISOTHERMAL
THERMOGRAVIMETRIC ANALYSIS IN SYNTHETIC FLUE GASa
ORGAN I C SOLI D % UNCORRECTED WEIGHT
UPTAKE OF SO b,c
2
in 3 hr. periods
Newsprint 1.9
Sawdust 3.0
Cotton -0-
Pyro lyzed PVC 2.2
Pyrolyzed PAN -0-
Poly(N-vinylcarbazole) 3.0
Nigrosin' -2.0
aThe synthetic flue gas with composition: 0.57% 'S02' 0.07% N02' 18.07%
C02 and 2.80% 02 was humidified by passage through a humidifier main-
tained at400C. Flow rate was 100 cc/min.
bNo correction was made for the slow thermal loss of the organic solids
maintained at 2150F.
CWeight uptake taken to be due entirely to S02'
.'
i .
I ,
, .
i.
';'7-
-------
l0669..6009-RO..OO
TABLE 2 ...
S02 SORPTION AT FOUR TEMPERATURES OF ORGANIC
SOLIDS BY ISOTHERMAL THERMOGRAVIMETRIC ANALYSISa
ORGANIC SOLID
TEMpoF
UNCORRECTED % WEIGHT
UPTAKE OF SO b
in 3 hr. tim~ periods
Pyrolized PAN
215 1.9 2.6c
250 -0- 0.9c
275 1.8 2.8c
300 -0- l.Oc
215 -0-
250 0.5
275 -0-
300 0.4
215 3.0
250 -0-
275 -0-
300 -0-
215 2.2
250 1.9
275 3.2
300 1.4
Newsprint
Cotton
Sawdust
aThe synthetic flue gas with composition: 0.57% S02' 0.07% N02' 18.07% C02
and 2.80% 02 was humidified by passage through a humidifier maintained at
40°C. Flow rate was 100 cc/min.
bWeight uptake taken to be due entirely to S02'
cCorrected weight %, correction factors determined from isothermal runs in
nitrogen: + 0.23%/hr. at 215°F, + 0.30%/hr. at 250°F, + 0.32%/hr at 275°F
+ 0.33%/hr. at 300°F.
-8-
-------
TABLE 3.
S02 Uptake of Cellulosics and Charcoals
Surface Initial 502 Uptake (a, d) Regeneration I(a, b, d) Regeneration II(a. b,. d)
Sorbe.nt Area
m2/g gig sorb. x 10-2 2 -2 gig sorb. x 10-2 g/m2 sorb. x 10-2 -2 g/m2 sorb. x 10-4
g/m sorb. x 10 gig sorb. x 10
Sawdust 0.5(c) 5.9 11.8 4.0 8.0 4.3 8.6
. Newspr.i nt 1.3(c) 4.0 3.1 4.6 3.5 5.0 3.9
Activated 1000 7.9 .0079 -- -- -- --
Charcoal (Approx)
Carbon -- 0 -- -- -- -- --
Black
I
1.0
I
. .
(a)30% 502 in N2 stream through sorbent at 2l50F .space velocity approximately 25 hr-l (neglecting volume occupied by sorbent)
(b)N2 stream at 3500F for 5 minutes, space velocity approxi~telY 250 hr-l (neglecting. volume occupied by sorbent)
(c)BET method with Krypton
(d)S02 uptake was determined by first passing a very. small amount of N2 gas through material at room temperature to remove
unsorbed and loosely bonded 502' then flushing with N2 at 3500F passing effluent through std. base and back titrating
with -"2504 .
.....
o
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1.0
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-------
10669-6009-RO-00
3.0
MORE DETAILED ACCUMULATION OF DATA ON NEWSPRINT
At this point, newsprint was selected as the prime candidate due to
the fact that it had a leading weight uptake and was, by far, the least
expensive and most easily obtainable in quantity of all the organic solids
in contentiQn. More detailed determination of rate of sorption of sulfur
dioxide as a function of temperature and sulfur dioxide concentration wa~
determined for newsprint by thermogravimetric analysis (Table 4).
It should be indicated that while the TGA technique, as applied to
cellulosics for S02 uptake, is exploratory in nature, a definite increase
in weight of cellulosics in synthetic flue gas is noted, which clearly
shows affinity of the specific cellulosic materials for S02 at flue gas
temperature.
The results indicate that paper picks up sulfur dioxide from flue gas
streams containing 0.57-2.0%,.v/v sulfur dioxide at temperatures of 2l5-302°F
with an ultimate capacity for sulfur dioxide of 10.2% by weight. The rate
, .
data shown in the tables were obtained under diffusion limited conditions at
approximately 10 vo1/hr-1 wherein the laminar layer about the paper sample
greatly influences the rate of diffusion controlled sorption of S02.
Sorption and desorption profiles were determined for packed beds of
shredded newsprint. Synthetic flue gas was passed through a packed bed of
paper maintained at 215°F at a velocity of 180 vols/hr for a period of 20
minutes. The sorption of S02 from the stream was followed by chemical ana-
lysis of the effluent flue gas. The results are shown in Figures 3 and 4.
The figures show initial rapid uptake of sulfur dioxide during the first
five to six minutes of sorption followed by a slower but indeed, signifi-
cant uptake out to the termination of the experiment. .
Desorption of sulfur dioxide from newsprint was found to give 22-26%
v/v S02 in the desorption gas stream at 450°F and 16.5% maximum percent
S02 v/v in the desorption gas stream at 350°F (See Table 5).
-10-
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TABLE 4
. RUN NO.
DETERMINATION OF RATE OF SORPTION OF SULFUR DIOXIDE BY NEWSPRINT AS A
. .
FUNCTION OF SULFUR DIOXIDE CONCENTRATION AND TEMPERATURE
CORRECTED a, b TOTAL % WEIGHT UPTAKE
~W lat, mg/hr OVER 7 HOUR PERIOD
S02 CONTENT
TEMP., of
1
2
3
0.57%
(O. 0149 ing/ml)
216 1. 74
248 2.00
302 0.62
216 2.34
248 0.81
302 0.38
216 4.20
248 1.77
302 1.59
216' 2.48
216 10.2d
t
. ....
....
.
4
5.
6
1.0%
(O. 0262 mg/ml)
7
8
9
2.0%
(O. 0524 mg/ml)
10
11
0.57%
(O. 0149 mg/ml)
aCorrection factors fgr pape~ weight loss at temgerature. determined in dry nitrogen (+ 0.67 mg/hr at 2150F,
+ 0.87 mg/hr at 248 F and + 0.95 mg/hr at 302 F).
bl00 cc/min flue gas flo~ for three hour time period the rate remains constant. Synthetic flue gas passed through
chumidifier at 40°C.
Weight newsprint, approx. 290 mg.
dThis sample was exposed to flue gas until rate leveled ~ff to zero for ultimate capacity dete rmination. .
....
o
0'1
0'1
1.0
I
0'1
o
o
1.0
I
::0
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-------
TABLE 5
DESORPTION OF S02 FROM NEWSPRINT
I "
--'
N
I
DESORPTION -" RUN la (450oPJ DESORPTION - RUN 2a (4500P) DESORPTION -" RUN Ja (J500P)
% Volume % Volume % Volwne
502 in 502 in 502 in
Time of Effluent S02 Time of Effluent 502 Time of Effluent 502
5ample Flow, Min Gas l!!ill ~ Flow, Min Gas l!!ill Sample Flow, Min Gas ~
Preflow (Expansion) 26.49 115.17 preflow (Expansion) 21.90 57.50 Preflow (Expansion) 16.50 40.00
1 1 4.33 16.48 1 1 13.00 20.58 1 1 12.30 15.58
2 2 1.08 13.23 2 1 9.20 17.82 2 1 9.60 16.10
3 2 0.36 2.24 3 1 4.80 10.43 3 1 3.60 7.74
4 1 0.47 1.50 4 1 " 1.70 4.10 4 1 4.10 8.48
5 1 1.27 0.54 5 1 1.00 2.30 5 1 0.90 2.08
6 1 0.98 0.86 6 1 1.50 3.62 6 1 1. 70 3.94
7 1 0.45 0.45 7 1 0.70 1.66 7 1 0.70 1.63
8 1 0.36 1.28 8 1 1.10 2.43 8 1 0.80 1. 76
9 1 0.32 " 0.38 9 1 0.70 1.44 9 1 0.60 1.31
10 1 0.28 0.29 10 1 0.60 1.47 10 1 0.70 1.38
11 1 0.17 0.19 11 1 0.50 1.12 . 11 1 0.50 1.06
12 1 0.11 {).48 12 1 0.80 1.66 12 1 0.50 1.06
13 1 0.13 0.29 13 1 0.50 1.12 13 1 0.30 0.80
14 1 0.20 0.70 14 1 0.40 0.90
15 1 0.20 0.70 15 1 0.30 0.80
aConditions
Run 1 Run 2 Run 3
Col. length 8 ft 8 ft 8 ft
Ullage 102 ee 102 ee 102 ee
Total Volume 109 ee 110 ee "111 ee
Weight Newsprint 9.73 g 8.32 9 8.32 9
Pulp Density 1.28 glee 1.04 glee 1.04 glee
Regen. Temperature 450°F 450°F 350°F
502 sorption stream for these experiments was a 30% S02 in nitrogen mixture.
--'
a
0\
0\
1.0
I
0\
a
a
1.0
I
:;:c
a
I"
a
a
-------
,
.....
w
,
2.0
~
<
w
~.
.In
V').
<
C>
w
::»
-' .
u. 1.0
Z
~
~
d"
V')
"#
°0
-------------------
502 CONCENTRATION IN UNTREATED FLUE GAS
. .
o
o
o
S02 CONCENTRATION IN EFFLUENT
AFTER FLOW THROUGH NEWSPRINT
5
10
TIME (MIN) .
15
FIGURE 3. S02 CONCENTRATION IN FLUE GAS EFFLUENT
o
20
.....
o
0\
0\
\0
I
0\
o
o
\0
I
:::0
o
I
o
o
-------
1.0
. .
----
I
~---
-----
-----
502 CONCENTRATION IN UNTREATED FLUE GAS
~ 0.8 0
«
w
«
~
V')
V') 0.6
«
C>
w
::>
~
. u.
- Z "
~ 0.4
.
~
:I>
N
0
V') .
:;R 0.2
0
..
10
TIME (MIN)
FIGURE 4. S02 CONCENTRATION IN DRY GAS EFFLUENT
O. -
o
5
502 CONCENTRATION IN EFFLUENT
AFTER FLOW THROUGH NEWSPRINT
15
-
20
-
a
0'1
0'1
\0
.
0'1
a
a
\0
.
:::0
a
..
a
a
-------
10669..6009~RO~00
. " , .. . . .,' .
4.0
APPENDIX A - THERMOGRAVIMETRIC ANALYSIS OF S02 SORPTION
A thermogravimetric analysis apparatus (TGA) was employed to monitor
the changes in weight of samples of newsprint as a simulated "f1ue gas II
was passed over the paper under isothermal conditions. The rate of weight
gain was recorded as a function of time on an X-Y recorder. The weight
gain data was employed to determine sorption rates at various temperatures.
An Aminco TGA was employed for the measurements of weight change. The
simulated flue gas was prepared by passing a dry gas of the proper composi-
tion through a humidification chamber, where the gas stream was saturated
with water vapor at the temperature maintained by the surrounding oven
(40°C in this study). The lines from the oven to the TGA apparatus were
insulated and heated to a temperature above the temperature maintained by
the oven in order to prevent condensation of water in the lines. The gas
flow into the humidification 'chamber was maintained at 100 cm3 per minute
by a metering valve. This flow rate provided a quantity of S02 which was
greatly in excess of the quantity sorbed in any given time period.
The standard sample holder (Figure 5') was used for screening, while a
'specia1 sample holder (Figure 6) was fabricated for the TGA balance for more
detailed accumulation of data experiments. This holder is essentially a
glass cage and suspension rod designed to maintain the sample in the de-
sired cylindrical geometry throughout the experiment. The gas flow enters
the furnace tube from the inlet tube at the bottom, passes around the sample,
and exists from the apparatus.
The synthetic flue gas mixtures containing 1% and 2% S02 were prepared
from the stock mixture purchased from Matheson, which has been described
above, by adding down pressures of pure S02 to a storage tank, then filling
to the required final pressure with the purchased flue gas mixture contain-
ing 0.57~ of S02' A sufficient quantity of gas mixture was prepared at
each S02 concentration to complete the scheduled runs at that composition.
This method of preparing the synthetic flue gas supply was preferred to the
method of mixing metered flows of component gases because of the greater
certainty of maintaining a known gas composition throughout each experimen-
tal run.
-15-
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1~669-6009-RO-00
~
GAS OUTLET
~
GAS INLET
SAMPLE IN .
~J)CIBLE
FIGURES. STANDARD TGA SAMPLE
HOLDER
\
. ,
FIGURE 6~ QUARTZ CAGE FOR
ISOTHERMAL TGA
EXPERlfflENTS .
The samples were rectangular pieces of newsprint 70. mm (2.8 inches)
by 80. mm (3.1 inches). No preconditioning of any kind was carried out.
Each sample weighed approximately 290 mg (6 x 10-4 lbs) with the exception
of the capacity run for which a 550/mg sample was utilized.
-16..
-------
r
I
I
Results
A series of 10 TGA runs of 3 hours duration were carried out at 102°C
(115°F), 120°C (248°F), and 150°C (302°F) at the S02 concentrations of 0.57,
1.0 and 2.0 volume percent. In addition to these runs, a single run of 10
hours duration was carried out at 102°C and an S02 concentration of 0.57
volume percent. Data from all eleven TGA runs are tabulated in Table 4.
Correlation of rate of weight gain with~increasing S02 concentration
was generally masked by variations in paper surface characteristics such as,
variations in amount of ink. Consequently, it was evident that further
treatment of the data, such as calculation desorption kinetics or activation
energies was not warranted.
The approximate capacity of the newspaper form of cellulosic was deter-
mined by TGA in run #11. For this determination, sample size was maximized
(551 mg) maintaining 100 mg full scale on the TGA apparatus balance.
-17-
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10669-6009-RO-00
5.0
APPENDIX B - SORPTION-DESORPTION EXPERIMENTS - ANALYSIS OF EFFLUENT FLUE GAS
Experimental work was performed on packed columns of paper pulp. The
sorption profiles reveal large initial sorption with lower level sorption
continuing for the duration of the 20-minute runs. The desorption profiles
indicate that a high percentage of the sorbed S02 is des orbed by a thermal
mechanism and that repeated use of the columns are possible.
Sorption Experiments
The test apparatus utilized in the sorption experiments is presented
schematically in Figure' 7. The system consisted of two cylinders contain-
ing N2 gas and synthetically-blended flue gas, respectively, a Fischer-
Porter flowmeter, a metering valve, a humidifier (omitted for Run Number 2),
a two-way' valve, the sorption column system, the column by-pass system, an
oven with an upper temperature limit of 400°C, a two-way stopcock, two
pyrex glass scrubber traps, a bubble meter, and the necessary stainless steel
lines and valves to construct the diagrammed system. The sorption experiments
were conducted by the following procedure:
a. The system was constructed as diagrammed.
b. The oven'temperature was allowed to reach equilibrium at the
required sorption temperature.
c. The flow rate was established using flue gas through the by-pass
system to determine approximate pressure and valve settings.
d. The scrubber traps were filled with 150 cc of 3% H202 solution.
e. The column valves are opened and the flue gas flow is diverted
through the column system. Timing begins when flow is seen in
the scrubber system.
f. Utilizing the two-way stopcock, the flue gas flow from the column
is diverted to a fresh scrubber trap at one-minute intervals.
During the one-minute periods, the scrubber trap is removed from
the system, the sample recovered and fresh peroxide replaced in
the trap. Once during each interval, a flow rate reading is
taken.
g. Sampling continues at one-minute intervals for 20 minutes. The
samples are analyzed by the procedure given in the following
paragraph.
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I .
....
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...
. TO HOOD
EXIT AND
BUBBLE
METER
ELECTRONIC
TIMER
TWO WAY
STOPCOCK
.
JOk H202
SCRUBBER
SYSTEM
OVEN
SORPTION
COLUMN
EMPTY COLUMN
BY-PASS SYSTEM
METERING VALVE
ROTOMETER
FIGURE 7. Sorption Test Apparatus
TWO'
WAY
VALVE
HUMIDIFIER
N2 GAS
FLUE GAS
SYNTHETIC
BLEND
....
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0'1
0'1
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0'1
o
o
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o
I
o
o
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10669-6009-RO-00
The samples obtained in Step f. above are analyzed by the following procedure:
a. The solutions are rinsed from the scrubbers into 250 cc beakers.
b. The solutions are reduced in volume from 150 cc to approximately
5 cc by boiling.
c. 4 cc of acetone and 3 drops of Su1fonazo III indicator solution
is added to the solution.
d. The resulting solution is titrated with 0.01 N Ba(C104)2 solution
to a blue end point.
e. Calculations are as follows:
A.
(mg S02 recovered) = T x N x 64.0
where:
T = Ba(C104)2 titer (m1)
N = Normality of Ba(C104)2 solution.
B.
A
% Vol S02' = 2.927
A
2.927 + C
where:
A = mg S02 recovered ,
C = Volume of gas passed through the system in the one-minute period
2.927 = S02 gas density mg/cc.
I
- j ,
I
Desorption Experiments
The desorption apparatus is presented schematically in Figure.8. The
system consists of two cylinders containing N2 gas and 30% S02 - N2 gas
blend respectively. an oven capable of 400°C temperature. desorption
column systems. a two stopcock. dual pyrex glass scrubbers. a marionette
bottle equipped with a two-way stopcock and a graduated cylinder. The
, '
desorption experiments were conducted by the following procedure:
a. The oven was allowed to reach thermal equilibrium at approximately
102°C.
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10669-6009-RO-00
b. A flow of 30% S02 gas blend was initiated through the column and
maintained at 25 column volumes per hour for 90 minutes. Satura-
tion is assumed. .
c. The column is reduced to ambient temperature and 200 cc of gas
displaced with N utilizing the scrubber system. A sample is
taken to determi~e the percentage of ellage swept by this pro-
cedure. . .
d. The column is isolated and the oven allowed to thermally equili-
brate at desorption temperature. .
e. When the column is at temperature, the valve connecting column
and scrubber system is opened and the gas allowed to expand
through the scrubber.
f. A slow N2 gas flow is initiated and 15 samples are obtained at
one-minute intervals as described in this sorption procedure.
The volume of N2 passed per minute is recorded by reading the
graduated cylinders at the completion of each one-minute sample
period.
g. The samples are analyzed and S02 recovered calculated by the
methods given for the sorption procedure.
The results for the sorption runs are given in Figures 3 and 4. The
results are reported in % vol/vol S02 as a function of time.
.
.
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TWO-WAY
STOPCOCK
I
N
N
I
MARIONETTE
BOTTLE
TWO-WAY
STOPCOCK
3% H202.
SCRUBBER
SYSTEM
-..,. .
COLUMN
SYSTEM
INTERCHANGABLE
CONNECTOR
N2
FIGURE 8. DESORPTION TEST APPARATUS
OVEN
.300k SO
2
GAS
.....
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en
en
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I
en
o
o
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I
o
o
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