cxEPA
United States
Environmental Protection
Agency
Industrial Environmental Research
Laboratory
Research Triangle Park NC 27711
EPA-600/2-78-146
July 1978
Research and Development
Chlorolysis Applied
to the Conversion of
Chlorocarbon
Residues
-------
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.
EPA REVIEW NOTICE
This report has been reviewed by the U.S. Environmental Protection Agency, and
approved for publication. Approval does not signify that the contents necessarily
reflect the views and policy of the Agency, nor does mention of trade names or
commercial products constitute endorsement or recommendation for use.
This document is available to the public through the National Technical Informa-
tion Service, Springfield, Virginia 22161.
-------
EPA-600/2-78-146
July 1978
Chlorolysis Applied to the Conversion
of Chlorocarbon Residues
by
C.E. Shannahan, H. Weber, G. Hauptman, and N. Carduck
Hoechst-Uhde Corporation
560 Sylvan Avenue
Englewood Cliffs, New Jersey 07632
Contract No. 68-03-2380
Program Element No. 1BB036
EPA Project Officers:
Max Samfield
Industrial Environmental Research Laboratory
Office of Energy, Minerals, and Industry
Research Triangle Park, NC 27711
and
Robert V. Swank
Environmental Research Center
College Station Road
Athens, Georgia 30605
Prepared for
U.S. ENVIRONMENTAL PROTECTION AGENCY
Office of Research and Development
Washington, DC 20460
-------
ABSTRACT
This program was initiated with the objective of determining the
technical feasibility and economic viability of eliminating, within the United
States, the discharge of large quantities of chlorocarbon residues which are
harmful to the environment through the use of a German process (chlorolysis),
which has been used commercially on almost identical residues, to produce a
saleable product.
The concept is based on installing a centrally located conversion plant
which would collect discharges from a number of nearby producers of
chlorocarbon residues in order to reduce transportation and processing costs
to a minimum and thereby increase the economic attractiveness of the plant.
Based on information obtained from an earlier EPA report,* it appears that a
commercial scale conversion plant could be located in either the Houston or
New Orleans area where approximately one-fourth to one-third of the total
amount of such residues now being produced could be converted to carbon
tetrachloride. The economic evaluation shows a nominal rate of return of
24.2% after taxes based upon typical utility and consumption figures including
credits for chemicals produced.
The technology selected and analyzed for this purpose is licensed by
Hoechst AG (FDR) and through Hoechst-Uhde Corporation (USA) and is known as
the "Chlorolysis Process." This process has been utilized in West Germany for
almost a decade. A large commercial plant (50,000 MT/yr) incorporating this
technology started operation last year. In addition to its established basis,
"chlorolysis" also offers the advantage of handling a wide variety of
chlorocarbon waste residues making it especially suitable for use in a
regional plant.
This report was submitted in fulfillment of Contract Number 68-03-2380 by
Hoechst-Uhde Corporation under the sponsorship of the U.S. Environmental
Protection Agency. The report covers a period from December 1976 to March
1978, and work was completed as of June 1978.
-------
CONTENTS
Abstract ii
Figures jy
Tables V"
Acknowledgments vi
1. Introduction 1
Purpose 1
Organization of study 1
2. Summary 3
3. Conclusions 4
4. Recommendations 5
5. Historical Background 6
Experimental work 6
Chlorocarbon survey 7
6. General Process Description 9
Introduction 9
Process description . . 9
Pretreatment of residues including light ends, heavy ends
and solvents. . , 11
Chlorolysis process 14
Incineration unit 23
Special investigations 26
Discussion of detailed technical findings 32
Plant design considerations - process unit 35
Environmental work . 37
7. Economic Analysis 40
References 47
Appendix
A. Design Specifications 48
Specifications of raw materials, utilities and auxiliaries. 48
Product specification 51
Waste streams 52
Consumption figures 53
iii
-------
FIGURES
Number Page
1 Block flow diagram of chlorolysis plant 10
2 Drying of light ends and treatment of heavy ends 12
3 Treatment of solvents 15
4 Reaction 16
5 Distillation I 18
6 Distillation II 20
7 Emergency absorption and high temperature heating 22
*
8 Incineration 24
9 Chorolysis plant for waste conversion, material balance
(VCM-wastes + solvents) 29
10 Chorolysis plant for waste conversion, material balance
(VCM-wastes) 30
11 Chlorolysis plant for Waste conversion, material balance
{VCM-wastes + HO) . 31
12 Correlation of chlorine emission rates and maximum ground level
concentration 38
A-l Sensitivity of chlorolysis plant economics to carbon tetra-
chloride price and disposal toll charge (base feed mixture) . . 54
A-2 Sensitivity of chlorolysis plant economics to carbon tetra-
chloride price and disposal toll charge (100% VCM residue feed) 55
iv
-------
TABLES
Number Page
1 Composition of Feedstock 27
2 Feedrate 28
3 Elemental Analysis of Feedstocks (%) 33
4 Economic Evaluation Summary, Base Case (Mixture I) Feed Residues. 41
5 Economic Evaluation Summary, 100% VCM Residue Feed (Mixture II) . 43
6 Summary of Results of Economic Calculations for Base and Mixture
II (100% VCM Residue) Feed Cases 45
-------
ACKNOWLEDGMENTS
Although numerous persons contributed to the successful completion of
this project, the authors wish to give special recognition to the two EPA
Project Officers involved, Drs. Max Samfield and Robert Swank. Without their
sustained, competent and constructive guidance and cooperation, the work would
not have been possible. In addition, the authors wish to give a special
thanks to Ms. Anne Warner of the Athens Environmental Research Laboratory, for
her many efforts in organizing and producing this final report, and to Mr.
Paul DesRosiers of the Office of Energy, Minerals, and Industry whose
dedication to the project's goals provided the necessary continuity to insure
its completion.
vi
-------
SECTION 1
INTRODUCTION
Chlorolysis is a recycling process through which by-product residues of
various chlorination synthesis processes may be used as feed in order to
convert them into useful industrial products, specifically, to carbon tetra-
chloride and hydrogen chloride.
PURPOSE
The purpose of this study is to determine the applicability of the
chlorolysis process to convert toxic and undesirable chlorocarbon wastes in an
ecologically satisfactory manner as well as analyze the economic basis on
which such a plant can be operated in the USA, Furthermore, the process
features the design of an enclosed system to handle the various potential
feedstock candidates that might be expected in a regional plant.
The precedent for this study involves other studies and developments as
follows:
1. Successful bench-scale tests on typical VCM waste, EPA Contract
Number 68-03-2380.
2. Independent test work performed by Diamond Shamrock, EPA Contract
Number 68-01-0457.
3. Commercial installations utilizing this process to produce 8,000 and
50,000 MT/yr CCli+ at Hoechst and 36,000 MT/yr in the USSR. The 8,000
MT/yr CCli^ pilot plant, which ran successfully for about four years,
was the basis for the construction of the 50,000 MT/yr CCl^ plant,
which is now on line.
4. Survey of chlorohydrocarbon wastes by Repro Chemical Corporation, EPA
Contract Number 68-03-0456.
5. The commercial application for a variety of toxic chlorinated
hydrocarbon wastes (Cj-C^) which the chlorolysis process offers.
ORGANIZATION OF STUDY
The design project report is contained in three volumes which are
described as follows:
-------
Volume I Summary of Process and Economics
Volume II Process Equipment and Flowsheets
Volume III Offsites, Cost Estimates, and Standards
Volume I contains the essential information required for evaluating the
process and has been prepared in accordance with NTIS requirements for public
dissemination. Volumes II and III are reference volumes which include
additional detailed information that provide the bases and backup for Volume
I.
-------
SECTION 2
SUMMARY
The results of this engineering design and economic feasibility study
establish a basis whereby toxic and hazardous chlorocarbon wastes can be
safely and economically converted into saleable end-products. Furthermore,
this process offers an important advantage of eliminating the biological
hazards associated with conventional alternative means of disposal, namely
deep well injection, and ocean, or land incineration. The process as offered
is essentially a closed system and has been proven commercially. Finally,
with regard to another of EPA's goals to promote resource recovery, it must be
pointed out that the process conserves vital natural resources, specifically
carbon and chlorine, which, instead of being destroyed, are processed into
useful end products.
The economic evaluation of such an installation processing approximately
25,000 MT/yr of residues indicates a rate of return (ROR) of 24.2% after taxes
(refer to Section 7). While this ROR, in itself, may not be attractive as an
investment under normal chemical industry standards, it must be recognized
that this return should be adjusted to reflect the costs and negative impact
on ROR associated with other means of disposal particularly the incineration
of valuable materials. It is essential that proper economic recognition be
given to the practical elimination of health and safety hazards which are
difficult to quantify as an increment of ROR.
-------
SECTION 3
CONCLUSIONS
1. The chlorolysis process is a commercially proven process to convert toxic
and hazardous chlorocarbon wastes into useful end products.
2. A plant can be designed to attain as nearly as possible a totally
enclosed system with minimal discharge to the environment.
3. The chlorolysis process eliminates the ecological and safety hazards
associated with other means of waste disposal, noteably deep wells, and
land or sea incineration.
4. The chlorolysis process is capable of converting low molecular weight
aliphatic chlorocarbons into a saleable product and is a suitable
candidate process for a regional disposal plant. The process is also
capable of handling aromatic chlorocarbons up to a maximum of 5% by
weight of the feedstock material on a blended basis (refer to Section 5,
Chlorocarbon Survey).
5. The chlorolysis process conserves vital natural resources, e.g., methane
and chlorine.
6. A regional plant which could produce 75,000 MT/yr of CCl^ (nominal 25,000
MT/yr residues processed) is estimated to cost about $29,000,000, at
present-day costs, exclusive of land, and would have a 24.2% ROR at this
capacity. This rate of return is based on a toll charge for handling
waste at $75/MT and a selling price for carbon tetrachloride at $300/MT
(refer to Section 7).
7. Actual plant capacity should be tailored to meet specific regional
requirements in order to realize optimum return consistent with previous
design concepts and capacities that have been proven commercially.
8. The amount of by-product anhydrous HC1 generated from the prototype
design plant would not justify further processing involving separate HC1
electrolysis and/or oxychlorination units, especially at present prices
for HC1 as muriatic acid. In the event the regional plant is located
near or adjacent to such processing plants, e.g., a VCM complex,
consideration should be given to the sale of anhydrous HC1 as feedstock,
thereby upgrading the value of the by-product HCl.
-------
SECTION 4
RECOMMENDATIONS
1. Develop and execute a program to familiarize appropriate governmental
agencies and the industrial sector with the advantages and economic
features of chlorolysis for toxic chlorocarbon waste disposal.
2. Investigate incentives available in the form of subsidies, public
financing, tax credits, etc., that might be made available through appro-
priate governmental agencies which would enhance the economic viability
and attractiveness of a regional chlorolysis plant.
-------
SECTION 5
HISTORICAL BACKGROUND
EXPERIMENTAL WORK
Recognizing the potential hazard to public health in handling hazardous
chlorocarbon residues from insecticide and herbicide plants in the USA as well
as to develop a method to dispose of Herbicide Orange (HO) which was used as a
defoliant in the Vietnam War, EPA authorized the Hoechst-Uhde Corporation
(HUC) in 1973 to undertake an experimental study to assess the applicability
of the Hoechst AG chlorolysis process to convert such wastes into carbon
tetrachloride. At the same time, in a parallel effort, EPA also determined
that sufficient chlorocarbon residues were being generated in the USA from
vinyl chloride monomer (VCM) and chlorinated solvent production alone to
sustain regional, multi-industrial waste source treatment facilities.
On this basis, experimental tests were conducted on blends of typical
chlorinated solvent wastes and Herbicide Orange (HO) to determine the
conversion that could be expected and whether the dioxin content of the HO
could be eliminated or reduced to an acceptable level. HO, which was used as
a military defoliant, is a mixture of equal parts of the n-butyl esters of
2,4-dichloro and 2,4,5-trichlorophenoxyacetic acids and also contains about
14-18 ppm tetrachlorodibenzo-p-dioxin (dioxin or TCDD), a very powerful
teratogen.
The tests included one blend of 32.4% HO and 67.6% distilled perchloro-
ethylene waste which was fed into an experimental bench scale reactor
operating at a reaction temperature of approximately 600°C and an operating
pressure of 2500 psig. Even this feed mixture was essentially all converted
to carbon tetrachloride, carbonyl chloride, and hydrogen chloride, with the
measured TCDD content of the product CCli,. under 1 ppb. The HO sulphur content
of 0.04% produced a corrosion rate in the nickel reactor of 6.4 mm/yr with
intercrystalline attack to a depth of 0.25 mm.
This experimental work plus information on the relative amounts of VCM
wastes generated compared to those involving pesticides led to the conclusion
that only approximately 5% of the total feed material to a regional
chlorolysis plant should consist of wastes such as HO. Mixtures containing
greater percentages would probably cause accelerated corrosion due to the more
prevalent traces of sulphur in insecticide and herbicide residues. The data
also strongly suggested that certain parts of any commercial chlorolysis
conversion reactor should be designed as "sacrificial." That is to say, the
-------
reactor should be segmened in the direction of reactant flow with particular
attention to the segement containing the zone of maximum reaction. It is this
particular segment which will undergo extra severe corrosion when extreme
sulphur conditions are imposed by the feedstock. This segment, therefore,
must be carefully positioned and monitored, and easily removed and replaced
with a backup unit always kept on site for this purpose.
CHLOROCARBON SURVEY
The volume of chlorocarbon wastes generated in the United States was
estimated to be approximately 190 MM Ibs/yr (86,400 MT). Current methods of
disposing of these wastes range from ocean discharge, burial, and deep well
injection to open-pit burning and enclosed incineration. About 55% of these
wastes are produced in the Gulf Coast area.
The identified residues are suitable feedstocks for a chlorolysis
operation provided they are pretreated to remove particulates, moisture, and
high boiling components.
Geographically, the chlorocarbon wastes are generated primarily at Gulf
Coast locations ranging from Corpus Christi, Texas, to New Orleans, Louisiana.
The apparent concentration along the Gulf Coast indicates that a regional
waste disposal unit would be viable. Such a regional facility should include
a chlorolysis unit, a waste pretreatment unit, and a conventional incineration
unit.
In addition to assessing the volume of wastes generated, it is also
necessary to consider the ultimate application and use of any product that can
be realized by the conversion of this material. At the present time,
chlorolysis represents a commercially proven technology capable of handling
the broad range of chlorinated hydrocarbons produced from process
manufacturing facilities in the chlorinated hydrocarbon field. Up to the
present time, chlorolysis has only been considered for the production of
carbon tetrachloride. Whether modifications could or should be initiated to
diversify the product slate is currently an unresolved matter. Accordingly,
the survey presented in the following paragraphs of this section of the report
is confined to the carbon tetrachloride market.
The total production capacity for carbon tetrachloride is estimated to be
about 540,000 U.S. tons per year (491,000 MT). However, this capacity is
flexible because perchloroethylene and carbon tetrachloride are coproducts.
The ratio of these products can be varied to satisfy swings in the
marketplace.
About 80% of the carbon tetrachloride produced is used in the manufacture
of Freon-ll and 12 for refrigeration and propellant usage. The 20% balance is
used for miscellaneous applications and export.
Growth of the carbon tetrachloride market has been closely related to the
growth of the fluorocarbon market. The growth of this market through 1975 had
been about 6% per year. The fastest growth has been experienced by the
propellant sector. This represents some 40% of the fluorocarbon market.
-------
However, the recent concern about the depletion of the ozone layer,
attributed to the C1 fluorochlorocarbons, has reduced the use of fluorocarbon
aerosol propellants by about 50%. This slowdown is expected to result in zero
growth until the ozone depletion question is resolved.
The volume of carbon tetrachloride that moves into the marketplace has
been reduced to about 440,000 U.S. tons. Further pressure on the aerosol
market will result in the volume dropping to about 340,000 U.S. tons, where it
would be expected to stabilize.
The product mix of plants that co-produce carbon tetrachloride with
either perchloroethylene or methylene chloride and chloroform can adjust to
compensate for these losses in the carbon tetrachloride market. Indeed, such
adjustments are already being made.
A chlorolysis unit rated at 24,000 U.S. tons per year of residue feed
would produce about 92,000 U.S. tons of carbon tetrachloride. This represents
about 30% of the projected stabilized market. This influx of new capacity
would have a significant effect on present producers. Further adjustments in
product mix would be necessary as would be the closure of marginal operations.
-------
SECTION 6
GENERAL PROCESS DESCRIPTION
INTRODUCTION
The chorolysis process includes the following plant units : pretreatment
of residues, reaction, distillation, and emergency absorption. In addition, a
high temperature incineration unit must be provided to eliminate any leftover
residues (see Figure 1) .
Residues cannot be introduced into the chlorolysis process as received,
i.e., in the form they have been supplied, they must be treated. Light ends,
for example, contain water which must be removed in a drying unit. VCM-
residues and solvent residues are contaminated with solids such as soot, which
must be removed in a falling film evaporator unit.
The treated residues are then passed to the reaction unit. Reaction
takes place at high pressure and high temperature. In the distillation unit,
the reaction products are separated, i.e., the HC1 and carbon tetrachloride
(CCltj) from the residues, which have not been completely converted, and the
excess feed chlorine. The latter two entities are then recycled to the
reactor. From the gaseous HC1, a 31% hydrochloric acid solution is produced
in an absorption column operating adiabatically .
An absorption unit is always available for both emergency and normal
shut-down of the plant. Thus, it is possible to treat all waste gases
containing Cl2 and HC1.
All residues left over from the pretreatment as well as those waste
waters containing chlorinated hydrocarbons are destroyed in the incinerator.
PROCESS DESCRIPTION
General
The following information describes a complete plant for the production
of carbon tetrachloride using chlorine and chlorinated hydrocarbons as feed-
stocks . Because of the wide range of possible feedstocks that can be
employed, the process will have a broad technical application for the
destructive removal of chlorinated hydrocarbon residues . The process was
developed based on the following basic conditions :
-------
C12
LE
HE
SOLV
DRYER
FALLING FILM EVAP.
FALLING FILM EVAP.
HC1 ABSORPTIOH
MURIATIC ACID
UNCONVERTED RESIDUES PLUS
RECYCLE C12
REACTION
DISTILLATION
CCli,
INCINERATION
NEUTR. WATER
Figure 1. Block flow diagram of chlorolysis plant.
-------
1. low consumption of chlorine and, consequently, low quantities of HC1
produced;
2. maximum utilization of residues resulting from broad spectrum of
industrial chlorination processes; and
3. no co-production of other chlorinated hydrocarbons.
Suitable raw materials are those residues from the production of vinyl
chloride monomer, chloromethanes, propylene oxide, allyl chloride, perchloro-
ethylene, as well as residues from benzene chlorination. The maximum content
of aromatics, however, should not in general exceed 5%, calculated as benzene.
As an example, carbon tetrachloride is to be produced in an adiabatic
reaction from chlorine and VCM-residues mixed with solvent wastes according to
the following stoichiometric equation:
1 kg residue + 2.734 kg C12 •* 3.010 kg CClk + (D
0.723 kg HCl + 0.001 kg Br2*
This equation is based on a typical feedstock analysis as specified in Chapter
3.
With a pressure of approximately 200 bar and a temperature of approxi-
mately 600°C, the conversion is more than 95% complete. Those heavy ends, not
completely converted (chiefly hexachlorobenzene) are separated from the
reaction products in the first distillation column and recycled to the reactor
to extinction.
PRETREATMENT OF RESIDUES INCLUDING LIGHT ENDS, HEAVY ENDS AND SOLVENTS
Drying of Light Ends (see Figure 2)
This unit is provided for pretreatment of wet light ends with a design
water content of 0.1% by weight. For the chlorolysis process, the moisture
content must be reduced to less than 20 ppm by weight.
The drying unit consists of two adsorbers and one regeneration system.
The wet light ends wastes are continuously fed as liquid into the unit (by
means of pumps), passing through one of two adsorbers L-151 A/B from bottom to
top. The dissolved water in the wastes are adsorbed on silica gel. The dried
organics leave the unit and flow into intermediate tank V-203.
While one adsorber is being charged, i.e., drying, the other is being
regenerated. Regeneration is achieved by activation with hot inert gas and
subsequent cooling. Regeneration takes place counter-currently to the drying
operation, i.e., from top to bottom. Prior to activation, the adsorber is
drained and the liquid sent into separator V-152.
*from traces of bromides in rock salt.
11
-------
DISTILLATE TO p-to<.*.B
RESIDUE TOIUCINEHATIQN
-lOiA.B
HUC DRAWING NUMBER
B-10393-7
Figure 2. Drying of light ends and treatment of heavy ends.
-------
Nitrogen is then introduced into the system as the activation gas,
circulated by means of blower K-151, subsequently heated up in E-152, and
eventually passed through the regenerating adsorber from top to bottom.
During the slow heating-up of the silica gel bed to about 80°C, the
remaining adhering chlorinated hydrocarbons are vaporized. Scrubber C-151 is
bypassed and the organics are condensed in cooler E-151, separated in V-151,
and finally passed into separator V-152. When the outlet temperature of the
gases rise to about 80 °C, the principal quantity of chlorinated hydrocarbons
have been removed and dehydration starts.
Since HC1 may be formed at the higher temperatures by decomposition of
the chlorinated hydrocarbons, the activation gas is passed through the NaOH-
scrubber C-151 when the temperature exceeds 80°C to prevent HC1 corrosion.
After scrubbing, the regeneration gas is cooled in E-151 and then passed
to blower K-151. The condensed water is passed via V-151 into separator V-
152. Activation is continued until the outlet temperature of the adsorber
rises sharply, which indicates the end of the dehydration phase.
At about 110°C, the steam to the heater E-152 is shut off and the gas is
circulated through the cooler for about 3 to 4 hours, while bypassing the NaOH
scrubber C-151, until the adsorber has cooled down sufficiently.
In the heavy ends treatment unit, the waste residues are separated from
tarry residues and soot by distillation.
A falling-film evaporator unit operating under vacuum (about 65 m bars)
was chosen to minimize the thermal load in view of the risk of polymerization
and coking.
The unit is equipped with two evaporators, because the evaporator
surfaces have to be cleaned from time to time.
The heavy ends wastes are pumped via filters into falling-film
evaporators E-201 A/B. Each evaporator is heated with saturated steam to
approximately 120°C-
The concentrated residues are separated from the vapors in V-201 A/B and
continuously drained. The residues flow via barometric leg into sealing drums
V-202 A/B and are continuously pumped into residue collecting vessel V-301 or
directly into the incinerator (unit 300).
The vapors are condensed in E-202 and E-203, then passed via barometric
leg into sealing drum V-205 and finally pumped into drum V-203.
Vacuum required for evaporation is generated by a multistage vacuum steam
jet unit J-201. Surface condensers are provided for condensation of the
driving steam to minimize the production of contaminated wastewater.
The second condenser E-203 is cooled by fluorocarbon R 12 to achieve the
maximum possible condensation.
13
-------
Small amounts of uncondensed organic components are carried over by the
condensed driving steam via the barometric leg into sealing drum V-204. From
here they are passed into the incineration unit .
For corrosion protection, it is recommended that small amounts of NHs be
fed into the suction end of the vacuum unit , thus obtaining slightly alkaline
wastewater .
Treatment of Solvents (see Figure 3)
In the treatment of solvents, the residues are separated from sooty solid
materials and polymers by carefully controlled distillation.
Distillation is effected in a falling-film evaporator under vacuum
(approximately 0.06 bar absolute) to minimize thermal load.
Two evaporators are provided, since they have to be cleaned regularly.
The solvents are transferred by pumps from tank farm through preheater E-251
into evaporator E-252 A/B. The falling-film evaporator is heated with steam
to approximately 197 °C. The heavies are separated from the distillate to be
chlorolyzed in separator V-251 A/B and are collected in receiver V-252 A/B.
By means of pump P-251 A/B, the heavies are fed directly to the incineration
unit. The solvents distillat are condensed in condenser E-253, which is then
cooled with warm water, and collected in pump feed vessel V-253. The
distilled solvents are then passed to the reaction vessel by pumps P-252 A/B.
The warm water cycle for cooling condenser E-253 consists of circulating
pump P-253 A/B, cooler E-255 and expansion vessel V-255. The vacuum required
for the operation of the falling-film evaporator E-252 A/B is generated by
means of steam injector J-251. A water-cooled second condenser unit E-254 is
installed between condenser E-253 and steam injector J-251. Traces of
uncondensed vapors from both solvents and driving steam are condensed in E-254
and collected in receiver V-254. This wastewater is then sent to the residue
incineration unit .
CHLOROLYSIS PROCESS
Reaction (see Figure 4)
The chlorolysis reactions are all exothermic. The following are the
equations of some characteristic oxidations , indicating the heat of reaction
at 1 bar and 300 °C.:
(kcal/kg feed)
CHC13 + C12 -»• CClij + HC1 -180 kcal
.+ 5 C12 -»• 2 CCl^ + 4 HC1 -1056 kcal
C6H6 + 15 C12 -»• 6 CCln. + 6 HC1 -3770 kcal
C6C16 + 9 C12 • •»• 6 CCln ~483 kcal
14
-------
SClVFMTS FROM P-106*,B
E-253
0 n
XTE-251 I |v-252A,B
P-251A.B
V-255
£-255
T
V-253
P-253A.8
P-252A.B
J-251
SOI VENTS DISTII.I ATE TO
RESIDUE TO INCIMERATIOrl
HUC DRAWING NUMBER
B-10394-7
Figure 3. Treatment of solvents.
-------
CTl
.SOLVENTS FROM P-252A.B
V-402
V-401
R ,_
HYDROGEN CHLORIDE TO py
C-S21~~U^
REACTION PRODUCT TO
c-soi"
QUENCH TETRA FROM
C-531
CHLORINE FROM
LIGHT ENDS AND
BL.
H
D C
P-403A.B
HEAVY ENDS DISTILLATE^
P ^
P-404A.B
E-40I ,
tr
) •:
P-401A.B
E-402A
)
P-402A.B
_ CHLORINE FROM C-521 .
BOTTOM PRODUCT FROM
C-501
HOC DRAWING NUMBUR
B-10396-7
Figure 4. Reaction.
-------
Reaction takes place at a temperature up to 600 C and 181 bars absolute.
The heat of reaction is sufficient for adiabatic operation. Auxiliary heat is
needed only for reactor startup. Final temperature is controlled by varying
the chlorine excess in the reactor, but must not exceed 620°C, due to
limitations of the materials of construction used for the reactor itself.
Optimum reaction conditions vary greatly and depend on the composition of the
feed residues. They are best determined by bench reactor experimentation.
For example, we know that when chlorolyzing benzene and alkyl benzenes,
hexachlorobenzene is formed as an intermediate which is itself only reacted
above 500°C. Prechlorination of olefin-containing feedstock with cold
chlorine at a temperature up to 70°C is recommended and provided in this
design study, since coking products are often formed during the reaction
between olefins and hot chlorine.
Therefore, liquid chlorine plus the pretreated light and heavy ends are
fed into the prechlorination unit, which consists of circulating pumps P-404
A/B, holding tank V-401, separator V-402, and cooler E-401. The
prechlorinated light and heavy ends are then mixed with the bottom product
from heavy ends column C-501 and transferred by means of high-pressure pumps
P-401 A/B into the reactor R-401.
The remaining required chlorine is fed into reactor R-401 by means of
special high-pressure pumps P-402 A/B. Before entering the reactor, feed
chlorine is heated to approximately 250°C by steam and Dowtherm in preheaters
E-402 A/B/C. A side stream of cold chlorine is fed by pump P-403 A/B into the
prechlorination unit.
Reactor R-401 consists of a nickel-lined steel tube. The outside walls
of the first sections of the reactor are provided with electrical heating.
Heating is required for start-up and compensation for heat losses if needed.
The final section of the reactor serves to quench the reaction products by
injection of carbon tetrachloride. In the quench section, the reaction
products are cooled from approximately 600°C to 500°C.
By pressure relief to 22 bars absolute, reaction products are cooled down
to 420°C as a result of the Joule-Thomson effect, before entering heavy ends
column C-501.
Reaction by-products include hexachlorobenzene, hexachloroethane,
carbonyl chloride, and carbon dioxide. Hexachlorobenzene and hexachloroethane
are actually intermediate products of chlorolysis. They are concentrated in
the bottom of heavy ends column C-501 and recycled back to the reactor. From
compounds in the feed stock containing oxygen, e.g., water, ether, etc.,
carbonyl chloride, and carbon dioxide are formed. Carbonyl chloride is
separated as a bottom product in the HC1 column C-521 and fed into the
incineration unit. CO2 is discharged together with HC1 as overhead from C-
521. The small amounts of soot and iron (III) chloride (catalyst in EDC
production) are discharged with hexachlorobenzene and hexachloroethane as
bottom products from the heavy ends column and separated by filtration. See
the following discussion and Figure 5 for details on separation and recovery
system design and operation.
17
-------
HYDROGEN CHLORIDE FROM V-4Q2
HYDROGEN CMI.ORIPE TO B I
00
f !
V-501
E-502
1 REACTOR R-401
ICHIORINE TO REACTOR R-M1
525 P-522A.8 P-521A.B
HOC DI'AWIt.'o NL'MBtP.
Figure 5. Distillation I.
-------
Heavy Ends, Raw CCl^ and HC1-column (see Figure 5)
In the heavy ends column C-501 unconverted hexachlorobenzene and
hexachloroethane are separated as bottom products and recycled to the reactor.
As overhead products, gaseous HC1, Cl2, and CCli^, small amounts of gaseous
COC12 and CC>2 are drawn off at a temperature of approximately 154°C and fed
into the raw CCli^ column C-511 for further separation. The pressure in the
heavy ends column is approximately 22 bars absolute, and the bottom
temperature is approximately 244°C. Dowtherm is used for heating the reboiler
E-502.
The overhead products of the heavy ends column are further separated in
the raw CCl^. column C-511. Overhead products, HC1, C02, Cl2, and COC12, are
drawn off at approximately 69°C and fed into the HC1 column C-521. The bottom
product, carbon tetrachloride, containing small amounts of bromine, carbonyl
chloride and traces of chlorine, hexachlorobenzene, and hexachloroethane, is
drawn off and passed into the pure CCl^ column C-531. The pressure in the raw
CCl^ column is approximately 21.5 bars absolute, the bottom temperature is
approximately 225°C. The heat required for the raw CCl^ column is supplied by
a Dowtherm-heated thermosyphon reboiler E-513.
The overhead product of the raw CCl^ column C-511 is separated in the HC1
column C-521. The overhead product, HC1, is drawn off with small amounts of
CO2 and supplied to battery limits for further use.
Chlorine, still containing some carbonyl chloride, is drawn off as a side
stream and recycled into the reactor together with fresh chlorine. As bottom
product, a mixture of carbonyl chloride, carbon tetrachloride and chlorine is
obtained, which is incinerated in unit 300. The pressure in the HC1 column
amounts to approximately 20.8 bars absolute. The column head temperature is
. o
approximately -8 C, whereas the column bottom is approximately 102 C.
The HC1 column is heated by reboiler E-522. For its heating medium,
Tripene (hexachlorobutadiene) was chosen due to its stability to chlorine.
Tripene is circulated by means of pumps P-522 A/B and heated from 104°C to
160°C in heat exchanger E-526 with medium-pressure steam. The vapors from the
column head are partially condensed in E-521, collected in vessel V-521, and
fed by pumps P-521 A/B as reflux. V-521 is thus designed with a buffer volume
surge capacity of approximately three hours of operation. If the HC1 supply
to the battery limits is interrupted, total condensation may take place.
Pure Carbon Tetrachloride Column (See Figure 6)
The bottom product of column C-511 is distilled into pure carbon tetra-
chloride in column C-531 where it is fed as liquid between the upper and
middle layers of the column packings. The side stream (product carbon
tetrachloride) is drawn off as a gas between the middle and lower layers of
the column packings. The gas is condensed in E-531 and finally stored in
intermediate tank V-531. By means of feed pumps P-531 A/B, the condensed
carbon tetrachloride is fed to the shift tanks V-534 A/B, which are
alternately operated. The shift tanks are discharged by pump P-534 into the
final CCltf product tank.
19
-------
HUC DPAWING NUMBKR
B-10398-7
Figure 6. Distillation II.
-------
The reboilers are heated with low-pressure steam (2 bars absolute). The
bottoms are fed by means of pumps P-532 A/B via cooler E-535 into collecting
tank V-532.
The overhead is condensed in E-532 and transferred into reflux drum V-
533. A portion of the distillate is refluxed to column C-531. The remainder
is pumped into collecting vessel V-532, mixed with the bottoms, and fed back
into the quenching section of reactor R-401.
Small amounts of uncondensed vapors containing CClt*, Cl2, HC1 and Br2 are
fed into absorber C-532 where treatment is effected by scrubbing with a 20%
NaOH solution. The bottom product of C-532 is separated in V-535 into caustic
wastewater and recycle carbon tetrachloride. The lighter wastewater flows via
an overflow into the incineration unit. The heavier carbon tetrachloride is
drawn off at the bottom of the separator, passed into vessel V-536 and then
recycled to the pure carbon tetrachloride column C-531 via driers L-531 A/B.
High Temperature Unit (See Figure 7)
A high temperature unit is necessary to provide the reboiler for columns
C-501 and C-511 with a suitable heating agent. The columns are operated at
pressures of 22 and 21 bars, respectively; producing bottom temperatures of
250°C and 220°C, respectively. Thus, it is not economical to use steam as a
heating agent.
Natural gas is used as fuel for the high temperature furnace B-701.
Dowtherm serves as the heating agent for the circulating system. Pumps P-701
A/B effect the forced circulation of Dowtherm through the heater and consumer
reboiler. The temperatures of the circulated Dowtherm are 305 °C at reboiler
supply and 275°C upon return to the furnace.
Vessel V-701 serves..as collection vessel for the whole Dowtherm system,
including piping and apparatus. Inside the collection vessel, a steam heating
coil prevents solidification of the Dowtherm. Pump P-702 is provided to fill
the system.
Emergency Absorption (See Figure 7)
The emergency absorption unit is provided for the treatment of waste vent
gases containing chlorine, hydrogen chloride, and carbonyl chloride. These
waste gases occur due to release of safety valves during shut-down of the
plant as a consequence of the pressure release in the columns and subsequent
purging with nitrogen, and also after pressure release and purging during a
change of filters. The absorption takes place in liquid injection scrubbers
by recirculating 20% NaOH according to the following reaction equations:
HC1 + NaOH -> NaCl + H2O;
Cl +2 NaOH -»• NaOCl + NaCl + H20;
COC12 + 4 NaOH -*• Na2CO3 + 2 NaCl + 2 H20.
21
-------
to
K)
R-401
COUECTINO LINE
BLOWDOWN FHQI
VALVE OF REACTOR
P-602C.O P-603A.B P-604A.B
L-601
HUC DRAWING NUMBER
B-10399-7
Figure 7. Emergency absorption and high temperature heating.
-------
The unit consists of four stages with three liquid injection scrubbers
connected in series, J-601, J-602, and J-603, followed by a scrubbing column,
C-601. Each injection scrubber is provided with its own storage tank, V-601,
V-602 A, and V-602 B and its own circulating pump P-601 A/B, P-602 A/B, and P-
602 C/D. The scrubber column, C-601, is also provided with its own pump, P-
603 A/B.
The absorption reactions are exothermic, therefore, three coolers, E-601,
E-602, and E-603, are also provided.
The first stage for emergency absorption deals only with the treatment of
gases released as a result of the opening of the reactor safety valve. The
other waste vent gases are passed directly into the second stage via the
suction of injector J-602. Those inerts and contaminate gases not yet
absorbed are then fed through the vent line of the storage tanks to the
suction of the third injector, and finally into the bottom of column C-601.
Bypass is provided to avoid vacuum in storage tank V-601, resulting from the
suction of injectors J-602 and J-603.
Depending on the NaOH required, it is possible to take a small amount of
fresh NaOH from storage tank V-603 and feed it by means of pumps P-604 A/B
into the bottom of scrubber C-601.
The NaOH flows via overflow control from the scrubbing column into V-602
B, then via overflow into V-602 A and from there into wastewater pit L-601.
Pit L-601 must also provide intermediate storage capacity for the larger
amount of bleaching liquor to be treated'in the wastewater purification plant.
This provision is necessary in view of the fact that the capacity of the
wastewater purification unit would not be sufficient in the case of
instantaneous discharge of the NaOH from the emergency absorption tanks.
INCINERATION UNIT (See Figure 8)
In the combustion unit, those leftover residues generated from both the
pretreatment of feedstock heavy ends and solvents and the bottom product of
the HCl-column are destroyed. In addition, all wastewater streams containing
traces of chlorinated hydrocarbons are incinerated. These aqueous wastes are
obtained in small quantities during the pure CCl^ distillation and in the
pretreatment units for feedstock light ends, heavy ends, and solvents (see
Figures 2, 3, and 6, and HUC Block Diagram Number B-10400-7 in Volume II) .
Waste products (chlorinated hydrocarbons) are fed to a burner system,. B-
301 and B-302, designed for incinerating liquid and/or gaseous residues. An
important factor to be considered in the incineration process is the caloric
value of the waste products themselves. This depends primarily on chlorine
content; a high chlorine content results in low caloric value and vice versa.
A chlorine content of 60-70% may normally be expected in the waste
products from the production of vinyl chloride monomer, and the caloric value
will be in the range of 2000 to 4000 kcal/kg. Complete combustion is unlikely
when the caloric value is below 3000 kcal/kg. Additional fuel must,
23
-------
to
D>^"'IIH"
V-301
P-301A.8
^COMBUSTION AIR ^J
Ix*"" —— — —•""
f^ WAU.R ICONfiEHSAlE I
C-302
NgQH
P-303A.B P-304A.8
PROCESS WATER
NEUTRALISED WATER
Figure 8. Incineration.
-------
therefore, be used by providing a separate gas burner or by mixing fuel oil
with the waste.
The waste, consisting of chlorinated hydrocarbons (C, H, Cl, O) possibly
containing traces of Fe, Cu and Al compounds, is atomized with the aid of
compressed air or steam in a special burner. Combustion air and water (e.g.,
wastewater) are also admitted to the combustion chamber. Incineration takes
place at a pressure of about 2000 mm water head and at temperatures in the
range of 1250°C.
The combustion product is a gaseous mixture of N2, Oa, HC1, CO2, Cl2, and
H20.
The equilibrium between water, chlorine, hydrogen chloride and oxygen in
the incinerator gases can be expressed as follows:
H20 + C12 "t 2 HC1 + h O2
Equilibrium constant:
(P HC1)2-(P
KP = (P H20)-(P C12) ,
where: P HC1 = partial pressure of HC1 in the reaction gas
P O2 = partial pressure of O2 in the reaction gas
P H2O = partial pressure of H2O in the reaction gas
P C12 = partial pressure of C12 in the reaction gas.
The reaction is temperature dependent.
The ratio of hydrogen chloride to chlorine in the reaction gas mixture
increases with rising temperature. Furthermore, the conversion (combustion)
of chlorinated hydrocarbons is improved at higher temperatures.
Excessive oxygen and hydrogen also affect the reaction. A lack of oxygen
in the reaction zone results in the formation of soot, whereas a great excess
of oxygen tends to increase the free chlorine content in the exhaust gas. An
excess of water suppresses the formation of free chlorine.
The reason for adding more water than required for the chemical
equilibrium (hydrogen demand) is to reduce the combustion temperature from
approximately 2000°C to approximately 1250°C to offer better protection to the
firebrick lining of the combustion chamber, which will "melt" at or near
1500°C.
Combustion Chamber System
The following design criteria for the combustion chamber are important:
25
-------
Temperature and residence time of the reactants in the combustion zone
are critical parameters. High temperatures permit short residence times and
vice versa, provided that complete combustion of the chlorinated hydrocarbons
is assured. Complete combustion may be defined as having been achieved when
the following parameter is greater than 99%:
(C02 - CO).
x 100
C02
In this case, a large combustion chamber was designed similar to that
used in the waste incineration process of Hoechst AG, ensuring complete
combustion of the chlorinated hydrocarbons with minimum formation of free
chlorine. These results are achieved by a long residence time (^_ 3 seconds)
of the reaction gases in the combustion zone and by introducing a relatively
large quantity of water.
Combustion Gas Treatment
The hot combustion gases from the incineration chamber, B-303, are fed
via a cooling tube to the quench system, C-301, where the gas temperature is
lowered from about 1000°C to about 100°C by injecting recirculated
hydrochloric acid. The cooling tube is bricklined. The quench column has an
acid-proof lining to protect the steel wall against corrosion.
Quench gas is fed to column C-302 where the HC1 is absorbed in "clean"
water. Additional hydrochloric acid thus formed collects in the bottom and is
sent partly to the quench acid collecting tank V-302, and partly to the
neutralization pit. The recirculating hydrolochloric acid concentration is
approximately 2.5% by weight.
SPECIAL INVESTIGATIONS
Feedstock
The bases for the feedstock composition calculations are the analyses
performed by Repro Chemical Corporation in the report entitled "Converting
Chlorohydrocarbon Wastes by Chlorolysis."3 Based upon the Repro data, four
residue mixtures had to be examined to cover the probable operating spectrum:
1. 60% by weight VCM residues and 40% by weight solvent wastes;
2. 100% VCM residues;
3. VCM residues and maximum oxygenated chlorinated hydrocarbons
(HO); and
4. Minimum VCM residues and maximum solvent wastes (shown to be same
as mixture 1).
Mixture 1 was considered as the "base case." The resulting feed
compositions are summarized in Table 1. Based upon a sized design capacity of
25,000 MT/yr of feed mixture 1, allowable feed rates for mixtures 1 through 3
are presented in Table 2. For mixtures 1 through 3, detailed material
balances were also calculated as shown in Figures 9 through 11.
26
-------
TABLE 1. COMPOSITION OF FEEDSTOCK
to
Components
1.
2.
3.
4.
5.
6.
7.
8.
9.
10.
11.
12.
13.
14.
15.
16.
17.
18.
19.
20.
21.
22.
Chloroethylene (VCM)
Chloroethane
Dichloroethylene
Trichlororr.e thane
Chlorobutatliene
Dichloroethane
Carbon Tetrachloride
Benzene
Trichloroethylene
Dichloropropane
Trichloroethane
Dichloropropene
Dichlorobutene
Trichloropropene
Chlorobenseno
Tetrachloroethane
Dichlorobenxene
Hex achloroe I: hane
Hexachlorobutadiene
HexacUioroburizene
2 , 4-Dichloro-Phenoxy-
Acetic-Acid n-Butylester
2,4,5-Tricr.loro-Phenoxy-
Acotic-Acid n-flutylejjter
Formula
C2U3C1
C2H5C1
C2H2C12
CHC13
C^HsCl
C2HltCl2
CO.,,
C6»G
C2HC13
C3H6C12
C2I13C13
C3H..C12
C,,H6C12
C3H3C13
C6«5C1
C2H2C1,,
C6H,,C12
C2C16
d.Cls
C6C16
CHOC1
12 1 ^ '> * 2
C12"l3°3C13
Molecular Boiling
Mass Point
kg/Kmol °C LE* IIED* Solvent*
62.50
64.52
96.94
119.38
88.54
98.96
153.82
78.11
131.39
112.99
133.42
110.97
125.00
145.42
112.56
167. 05
147.00
236.74
260.76
284.78
277.15
311.59
-13.3 10.9
13.1 3.8
32-60.3 4.5 0.5
61.7 9.9
59.4-68 14.5 2.7
57-84 30.4 2.2
76.5 16.9 0.7
80.1 6.2
87.2 2.9
69.7-120.4 - 1.7
74-113 - 56.6
77-112 - 2.7
101-156 - 26.0
114-142 - 0.7
132.2 - 2.8
130-146 - 2.3
172-179 - 1.1
186 - - 25.0
215 - - 65.0
322 - _ 10_Q
146 - -
£1 mm Ilg)
-
X 100.0 100.0 100.0
VCM-Solv* .VCM*
60% VCM 33% LE
40% Solv 67% HED
2.2
0.3
1.1
2.0
4.0
6.9
3.5
1.2
0.6
0.7
22.7
1.1
10.4
0.3
1.1
0.9
0.4
10.0
26.0
4.0
— -
—
100.0
3.6
1.3
1.8
3.3
6.6
11.5
6.0
2.0
1.0
1.1
37.9
1.8
17.4
0.5
1.9
1.6
0.7
-
-
-
-
-
100.0
VCM+liO*
95'« VCM
51 iiO
3.4
1.2
1.7
3.1
6.3
10.9
5.7
1.9
1.0
1.0
36.0
1.7
16.6
0.5
1.8
1 .5
0.7
-
-
-
2 .5
2.5
100.0
— . — — M ~^— ~~~~~ "~ - —
weight.
-------
TABLE 2. FEEDRATE
03
Componc:nts
1.
2.
3.
4.
5.
6.
7.
8.
9.
10.
11.
12.
13.
14.
15.
16.
17.
18.
19.
20.
21.
22.
Chloroethylene (VCM)
Chloroethane
Di Chloroethylene
Trichloromethane
Chlorobutadiene
Di chloroethane
Carbon Tetrachloride
Benzene
Trichloroethylene
Dichloropropane
Trichloroe thane
Dichloropropene
Dichlorobutene
Trichloropropene
Chlorobenzene
Tetrachloroethane
Dichlorobenzene
Hexachloroethane
Hexachlorobutadiene
Hexachlorobenzene
2 , 4-Dichloro-Phenoxy-
Acetic-Acid n-flutylester
2,4, 5-Trichloro-Phenoxy-
Acetic-Acid n-Butylester
Formula !,!•:* 11KD* Solventn*
C2H3C1 67 -
C2H5C1 24 -
C2H2C12 20 6
CHC13 61 -
C,,H5C1 90 34
C2H4C12 188 28
CC1,, 105 9
C6H6 38 -
C2HC13 18 -
C3H6C12 - 21
C2H3C13 - 7H
C-jHt.Cl;, - 34
C,(H6C12 - 326
C3H3C13 9
C6II5C1 35
CjHjCl,, - 29
C6iti,Cl2 - 14
C2C16 - - 312.5
C|»C16 - - 812.5
CeCl6 - - 125
c^ii^oadj -
Cj2H13O3Cl3- -
I 619 1256 1250
VCM t Sol v.* VCM*
60* VCM 33*. LE
401. Polv. 67i. l!i-:D
67
24
34
Gl
124
216
114
38
18
21
711
34
326
9
35
29
14
312.5
812.5
125
-
-
3125
113
41
56
103
206
359
188
63
31
34
1184
56
544
16
59
50
22
-
-
_
-
-
3125
VCM+liO*
95% VCM
5% !!O
106
33
53
97
197
341
178
59
31
31
1125
53
519
16
56
47
22
-
_
_
78
78
3125
*kg/h.
-------
CHLORINE
02 13
C12 8496
H20 1
C12 15306
COC12 65
CCl,. 6
15377
S
f HC1-
C12 9
CCC12 36
CCli, 2
47
I
02 1
C12 521
H20 <1
X M2
02 12
C12 7975
H20 1
' 7988
1
HC153/
B T
CO2 10
HC1 2261
2271
.
VCM-WASTES
LE 619
HE 1256
1865 \f
*
+ SOLVENTS SODIUM HYDROXIDE 20%
i
PRECHLORINATION
DRUM F-401
02 1
LESHE 2343
2344
I
1 1250 SOLV
PHECHLORINATED
t
REACTOR T-401
1 .
C02 10
HC1 2208
C12 15316
COC12 104
Br2 3
CCli, 10334
C2C16 128
CgClfi 382
28485
I
QUENCH T-401
C12 <1
COC12 2
Br2 7
CCli, 5185
C2C16 <1
C6C16 <1
5194
J 1
C02 10
HC1 2208
C12 15316
COC12 106
Br2 10
CCli, 15519
C2C16 128
Cede 382
33679
HEAVY ENDS COLUMN C-501J— ^
C02 10
HC1 2208
C12 15315
COC12 101
CCli, 8
17642
\\
CCli, 4548
C2C16 <1
C6C16 <1
4548
<
^>-| FINAL CC14
— B S
1 *
T
C02 10
HC1 2208
C12 15316
COC12 106
Br2 10
CCli, 14503
C2C16 <1
CfiCls <1
32153
CCl!, 1016
C2C16 128
C6C16 382
1526
1
NaOH 7
H20 30
C12
COC1
Br
CCl
X
I 1
NaOH SCRUBBER C-532 1
I NaOCl 1
NaCl 4
Na?C03 3
I NaOBr 2
1 NaBr 2
1 H2O 32
CCli, 134
J\l
SEPARATOR V-535 1
CCli, 134 1
134 1
Waste water
NaOCl 1
NaCl 4
Na2C03 3
NaOBr 2
NaBr 2
H20 32
44
)LUMN C-511 DRYER L-531 |
B
C12 1
COC12 5
Br2 10
CCli, 14495
C2C16 <1
CcClt <1
14511
i
CCli,
| COC12 | HYDROGEN CHLORIDE | FINAL CC14
CCli, 134 j
Waste water
H2O 1
C12 <1
COC12 2
Br2 7
CCli, 637
DIMENSION: kg/h
B = Bottom
S = sidestream
T = Top
Figure 9. Chlorolysis plant for waste conversion, material balance
(VCM-wastes + solvents).
HUC Drawing No. B05541-3
29
-------
02
Cl->
H26
02
C12
H20
17
10838
1
10856
C12 9418
COC12 821
CCli, 4]
95041
1
868
<1
869
VCM-WASTES
*
Ht %
|LE 1031 33
JKE 2094 67
' 3125 100
t
— T PRECHLORINATION
DRUM
B
I
REACTOR
1 ,
F-401
02 1
VCM 3906 (Prechlo
3907
T-401
C02 14
HC1 3644
C12 9431
COC12 134
Br2 3
CCli, 12194
C2C16 144
CsClfi 433
25997
QUENCH T-401
COC12 3
Br2 8
CCli, 4789
C2C16 <1
C6C16 _<1
4800
\|
B ,
C02 14
HC1 3644
C12 9431
CCC12 137
Br2 11
CCli, 16983
C2C16 144
CfcClfc 433
30797
|
HEAVY ENDS COLUMN C-5011
SODIUM HYDROXIDE 20% [
CCli, 1153
C2C16 144
C6C16 433
1730
HC1-COLUMN C-521
C12
12
L2 48
. 3
63
1
B
coci, 1
2 |
T
|C02 14
HC1 3731
1 3745
T
«•
ccii,
C2C1(
C6C1(
p
SJ F
1 '
HYDROGEN CHLORIDE
NaOH 9
H20 37
46
C12 1
COC12 4
Br2 3
CCli, 135
It 3
NaOH SCRUBBER C-532
NaOCl
NaCl
Na2C03
NaOBr
NaBr
CCl^
H20
1
6
4
2
2
135
39
189
SEPARATOR V-535
C02
HC1
14
3644
C12 9430
COC12 130
13225
CO2
HC1
C12
COC12
Br2
CCli,
C2C16
14
3544
9431
137
11
16983
144
433
30797
CC1,,
H2O
Waste water
NaOCl
NaCl
Na CO
NaOBr
NaBr
HO
1
6
4
2
2
39
.54
RAW CC1. COLUMN C-511
DRYER L-531
Kli, 4140
^2^16 1
4140
1
B
C12
COC12
Br2
ccii,
C2Cl6
i
7
" CClu 135 /
15842
r
Haste watc
FINAL CC1. COLUMN C-531
4 rr
11034
FINAL CC1
Br
CC1^
8
649
660
DIMENSION: kg/h
B = Bottom
S = Sidestream
T - Top
Figure 10. Chlorolysis plant for waste conversion, material balance
(VCM-wastes).
HUC Drawing No. B05542-3
30
-------
CHLORINE
02
H20
1
825
826
VCM-WASTES + HO
17
11383
11401
C12 9493
COC12 298
CCli, 4
9795
SODIUM HYDROXIDE 20%
HE
HO
2969
156
3125
95
5
100
PRECHLORINATION
DRUM F-401
1
02
VCM+HO
3865 (Prechlorlnated)
3866
REACTOR T-401
C02
HC1
C12
COC12
Br2
CCli,
C2C16
C6C16
21
3762
9538
478
3
12743
186
557
NaOH 23.5
H20 94.5
118.0
C12 1
COC12 13
Br2 3
CC1,, 348
365
HC1-COLUMN C-521
CC12 44
COC12 167
CClft 8
219
B
C02
HC1
COC1
as/
h'
21
3847
3868
'
-
T
C
C
B
C
C
c
c
H
C
c
c
I
27288
QUENCH T-401
12
OC12
r2
Cli,
2^6
6«6
5
20
5299
6324
1
C02
HC1
C12
COC12
Br2
ccii,
C2C16
CSC16
21
3762
9538
483
23
18042
186
557
, 32612
HEAVY ENDS COLOTBJ
02
Cl
12
OC3?
Cl,,
RAW
cell,
C2C16
21
3762
9537
465
12
13797
|
T
C0?
HC1
C12
COC12
Br2
CCli,
C2C16
C-501
h
21
3762
9538
483
23
16559
^v
C
H
1
• 1
NaOH SCRUBBER C-532
I
NaOCl 1
NaCl 16
Na2C03 14
NaOBr 2
NaBr 2
CCli, 348
H2O 100
483
SEPARATOR V-535 I
Cli, 348
2° _Si
, 3038fi
CC14 COLUMN C-511
B
3627
362T
1
C12
COC12
Br2
CCli,
C2C16
C6Cl6
18
23
16547
16589
*-^4 FINAL CC14 COLUMN C-531
I
i
r
*OGEN CHLORIDE 1
|
s
CCli,
FINAL CC14
11248
T
Waste water
NaOCl 1
NaCl 16
Na2C03 14
NaOBr 2
NaBr 2
H20 100
ns
DRYER L-531
CC1,, 348
Haste water
H20 <1
»
\
COC1, 5
Br2 " 2n
CClt, 1672
DIMENSION: kg/h
B = Bottom
S = sidestream
T = Top
Figure 11. Chlorolysis plant for waste conversion, material balance
(VCM-wastes + HO) . mr Drawing NQ
31
-------
For the composition of light ends as specified by Repro in Table 1, the
numbers with two digits following the decimal point were rounded off and the
difference from 100%, amounting to 0.2%, was assumed to be dichloroethane.
The unknown components of heavy ends distillate (HED) were calculated as
trichloroethane. The undefined aromatic chlorocarbon components of 3.9% were
apportioned into 2.8% chlorobenzene and 1.1% dichlorobenzene corresponding to
the observed mass ratio between chloro- and dichlorobenzene in VCM residues of
Hoechst AG, without considering the other aromatics. In this way, an aromatic
content of 3.74% as benzene was obtained for the HED.
Moreover, in deviation from the Repro data, a bromine content of 0.2% in
HED was assumed. Bromine results from rock salt and is taken up with the
chlorine gas in the electrolysis process. In the production of dichlorethane,
bromine compounds, higher boiling than EDC, are obtained. These compounds are
concentrated in the VCM heavy ends and discharged together with them.
The concentration of sulfur and sulfur-containing compounds is limited to
25 ppm S in all feed residues in order to avoid accelerated corrosion of the
nickel reactor tube. The resulting elemental compositions for the three
feedstocks are summarized in Table 3.
CAPACITY OF THE PLANT
Plant design was based on a capacity of 25,000 MT/yr of chlorohydrocarbon
waste residue feedstock mixture 1 as specified in the Special Investigations
portion of this chapter with an on-stream time of 8000 hrs/yr. The rest of
the year (760 hours) is provided for shut-down, maintenance, etc.
DISCUSSION OF DETAILED TECHNICAL FINDINGS
Base Case Residue Mixture 1 and Mixture 4
All equipment was designed and sized for mixture 1. According to the
experience of Hoechst AG with various chlorohydrocarbon wastes, 40% will be
the maximum solvents waste quantity which can be mixed with VCM residues.
Mixture 1 is, thus, identical to mixture 4. The reason for this limitation is
the high starting (chlorolysis initiation) temperature of this mixture in the
reactor which is estimated to be approximately 200°C. Accordingly, feed
chlorine would have to be heated up to 250°C. This is the upper limit based
upon the materials of construction employed and the manufacture's limits for
the high-pressure chlorine heat exchanger, E-402.
Also for this mixture—not yet having been experimentally examined—a
chlorine excess of 180% of the stoichiometric requirement is calculated as
being necessary to achieve proper conversions.
Mixture 2
Bottlenecks would result at the following points, in comparison with
mixture 1, when using 25,000 MT/yr residues of mixture 2: prechlorination,
HCl-column, and refrigerating unit. It was decided that it was more
32
-------
TABLE 3. ELEMENTAL ANALYSIS OF FEEDSTOCKS(%)
VCMVCM+Solv.VCM+HO
33% LE 60% VCM 95% VCM
Elements 67% RED 40% Solv. 5% HO
c
H
Cl
Br
0
27.9
3.3
68.7
0.1
_
23.5
2.0
74.4
0.1
_
29.0
3.4
66.7
0.1
0.8
100.0 100.0. 100.0
33
-------
economical to utilize the reactor at 100% efficiency and to eliminate the
bottlenecks in these other pieces of equipment.
For mixture 2, the required preheating temperature of the chlorine feed
is about 120°C with an 80% chlorine excess.
Mixture 3
The material balance for case 3 shows 5% oxygenated residues (HO) added
to VCM residues. It is not possible to mix a higher percentage of oxygenated
residues (HO) since the content of aromatic calculated as benzene in the
mixture would exceed the 5% experience limit.
The reason for this limit is the maximum permissible design temperature
(620°C) of the reactor. For an aromatic content greater than 5% by weight,
the final temperature would have to exceed 620°C to achieve the necessary
conversions.
For mixture 3, an 80% excess chlorine is required with a preheating
temperature of 120°C.
Treatment of Byproducts
The detailed material balances (see Figures 9 through 11) for the
chlorolysis process show the amount of byproducts being produced.
The quality of HC1 produced is sufficient for electrolysis and oxychlori-
nation, but the HC1 amount is too small to permit economical operation of such
independent units in a waste complex of the capacity envisaged. Economic
operation is possible only if HC1 from other sources is available or if the
amount of HCl chlorolysis can be added to existing electrolysis or
oxychlorination plants.
Transporation of liquid HCl is permitted only in pressure vessels
designed for a pressure of about 120 bar. Consequently, economical transport
of large quantities is not possible over long distances. Therefore, it is
recommended that the chlorolysis plant be sited within a corresponding
production complex which can use the gaseous HCl produced by direct pipeline
transfer.
The carbonyl chloride obtained in the bottom of the HCl-column is
contaminated by chlorine and CCl^. Carbonyl chloride has to be rectified, to
allow for its usage as feedstock in an isocyanate process. Since the quantity
obtained (36 kg/hr COC12) is very small, it is not economical to provide a
separate column, a storage vessel with filling device, and all the safety
facilities required for such a hazardous material. Thus, the stream taken
from the bottom of the HCl column is passed directly to the residue combustion
plant. Even when HO or similarly oxidized organic is mixed with the VCM
residues, the quantity of carbonyl chloride is only 167 kg/hr. The
purification of this COC12 would be economical only if the chlorolysis plant
were built within a chemical complex, where the byproducts could be utilized
by direct pipeline transfer.
34
-------
PLANT DESIGN CONSIDERATIONS - PROCESS UNIT
Pretreatment of Residues
The residues as supplied cannot be used directly. The light ends, for
example, contain vip to 0.1% dissolved water, which must be eliminated by means
of a silica gel adsorption drying plant.
Heavy ends and solvents contain mostly solid materials, e.g., soot,
coking products or polymers, which are not quantitatively converted to carbon
tetrachloride and hydrogen chloride in the chlorolysis process. Because these
components and non-volatile inorganic compounds accumulate in the reactor,
they must be separated by filtration or, as in the case of solutions by
distillation, e.g., in a falling-film evaporator. Non-volatile inorganic
compounds like iron (III) chloride tend to be deposited in the bottom of the
heavy ends column and are filtered out when the bottom product is recycled to
the reactor.
When treating the solvents, it must be considered that the component
hexachlorobenzene (HCB) contained in the residues is not completely soluble at
ambient temperature. Therefore, this residue must be maintained at about 100-
110°C in the hold tank to keep the HCB soluble.
The following conclusions are drawn for the design of equipment based
upon the material balance for the base case as compared to those of the other
mixtures, 2 and 3.
Drying of Light Ends (Unit 150)
The feed rate of light ends for mixture 2 amounts to 1031 kg/hr and for
mixture 3, 980 kg/hr in comparison with 619 kg/hr for the base case. This
corresponds to a capacity factor of 166% for operation with mixture 2 compared
with the base case. The drier capacity is higher and designed for a feed rate
of 2 m3/hr light ends, since driers L-151 A/B are also designed for drying
during start-up of the plant. Specified drier capacity is, thus, sufficient
for both operations.
Treatment of Heavy Ends/Solvents (Unit 200/250)
Two falling-film evaporator units operated alternately are provided for
operation with the base case mixture. The capacity for treating heavy ends is
1256 kg/hr and for solvents 1250 kg/hr so that the total capacity amounts to
2506 kg/hr. Both units can be used in parallel for operation with heavy ends
(maximum 2094 kg/hr).
Reaction Part (Unit 400)
Prechlorination—
The light and heavy ends must be at first prechlorinated; however, the
solvents can be directly fed into the reactor without prechlorination. For
operation with mixture 2, the sum of the feed rates of light and heavy ends
35
-------
into the prechlorinator amounts to 3125 kg/hr compared to 1875 kg/hr for the
base case with required chlorine quantities of 869 kg/hr and 522 kg/hr,
respectively. This means that the prechlorination quantity for the base
case is too small by the factor of 166%.
In order to provide more flexibility when using all residue mixtures,
the specified prechlorination equipment has been designed for mixtures 2 and
3.
Reaction—
In the reaction section, pumps P-401 A/B are designed for case 3,
because the quantity of mixture 3 is 20% higher than in the base case. With
regard to the feed rate, the capacity of reactor R-401 is sufficient for
operation with all residue mixtures.
Separation Unit 500
The equipment in the distillation section has been laid out, in any
case, according to the maximum load. Because of the high chlorine excess,
the load in the heavy ends columns C-501 and in the crude CCl^ column C-511
is maximum when mixture 1 is used. For mixtures 2 and 3, the HCl-cblumn
C-521 and pure CClt* column C-531 are loaded at a higher rate compared to the
base case.
Incinerator (Unit 300)
The incineration unit is designed for mixtures 2 and 3 with a feed
capacity of 600 kg/hr and an on-stream time of 8000 hrs/yr. Mixtures 2 and
3 provide the maximum residual wastes from the pretreatment units.
It is necessary to add water to wastes with a high heating value in
order to regulate the reaction temperature in the combustion chamber. For
this reason, most of the small waste water streams (shown in Figures 2, 3,
and 6, and HOC Drawing Number B-10400-7, Volume II) containing traces of
chlorinated hydrocarbons are used togehter with additional "clean" water to
control the reaction temperature in the incinerator.
The off-gas is treated by scrubber C-302 operating with "clean" water.
In case of perfect combustion, no free chlorine is formed and HC1 can be
removed thoroughly with water to meet emission standards.
In case of imperfect or incomplete conbustion, i.e., with too much
excess oxygen, 500 (weight) ppm of chlorine may be obtained in the vent gas
if washed only with water. To meet emission standards and to prevent this
high chlorine content at the stack exhaust, the following provisions were
made:
1. the stack height was fixed at 40 m, and
36
-------
2. a small amount of caustic soda was specified to be added to the
washing water to eliminate the traces of chlorine and HC1. Thus, a
chlorine content of less than 20 (weight) ppm is expected.
Based upon .these specifications and assumptions, i.e., a chlorine
content at stack exit less than 20 weight ppm, a stack height of 40 m, and
an allowable ground level concentration of 0.1 mg/m3, the emission standards
will not be exceeded up to a wind velocity of 0.1 m/sec. The calculations
were checked using the nomograph in Figure 12.3 According to the lengthy
experience of Hoechst AG in operating incineration plants, no high boilers
such as HCB and others will be detectable in the vent gas if the indicated
design and operating specifications are followed.
The HC1 acid produced (approximately 2.5 weight %) in the vent scrubber
system is neutralized in a pit and then sent to battery limits for discharge
as waste salt water.
Design Specifications
Detailed specifications for raw materials, utilities, auxiliaries,
products, etc., were developed by combining Hoechst operating experience
(Federal Republic of Germany) with American-Gulf Coast area chemical
systhesis industry needs and experience. The resulting design values are
presented in detail in Appendix A.
ENVIRONMENTAL WORK
Introduction
From a variety of industrial chlorination processes, e.g., vinyl
chloride and chlorinated solvent and pesticide production, toxic and
hazardous byproduct residues are obtained which have to be disposed of.
Today, the disposition of these wastes has become a serious environmental,
social, and even potentially a health problem. Industry is now forced by
environmental and safety regulations to produce as little waste as possible,
and then to have this waste treated with minimum impact on the environment.
For this reason, industry strives to convert its wastes into products that
may be utilized again, whenever and wherever it is possible.
Several processes for disposal of chlorinated residues by conversion to
other products have been applied at commercial scale:
1. Incineration with scrubbing where muriatic acid is produced, from
which part of the hydrogen chloride may be recovered (chlorine
value);
2. A catalytic cracking process taking place in conjunction with the
oxychlorination process (to produce vinyl chloride precursor) in
which the hydrogen chloride of the combustion gas is consumed and
converted to ethylene dichloride (recovers some chlorine and carbon
values); and
37
-------
H Q X
n ™
~i
-
-
-
-
_
.
-
.
•
.
.
•
•
U!
00
•
IOOO \
700 .
5OO
400 '
300
J50
200 .
I *^/>
i 3w
100
70 "
• 50 •
30 •
•20 .
13
10
IOOO -
600
600 ]
5OO
400
300 .
• 250
• ?00
• '50
• 100
•70 '
• 50
•30 •
20
•IS
•10
IOOO
000 -
600
500
• 4OO "
300
250
2OO
150
100
•70
•50 -
• 30 '
•20 -
•15
• O -i
looo
BOO '
700
COO
500
400
.
soo
•250
• 200
ISO
• 100
• 70
• SO
• 30
-SO "
• 15
• 10 -
SOO
400
• 300 •
250
• 25O
ISO
too
70
50
• 40
• 3O
- 20
• 15
• K>
200
ISO
100
70
SO
• 40
30
20
• 15
• 10
A B C D E F
STABILITY CATEGORIES
U
0.1-
0.2-
03-
04 —
0.5 ~"
0,7 ..
2-
3-
5-
7~
10-
20-
30-
40-
50-
70-
IOO-
-0.1
— 0.2
^^^^|||
-0«""^-
"* "0.3 "^^^^^
~°'7 ~~~^~~^
^^~~~-^
— 3
•^ 4
-5
- 7
-10
-20
~40
H— *t y
-50
- 70
-»00
BOO-
«oo •
soo •
400-
200
100-
80 •
60-
40 •
20-
10-
8 -
6-
4 *
2-
~~v- 0.8 •
^•~-»_^^ 0.6-
~^_^ 0.4.
Jj~^^_^
PERMISSIBLE ^^1.
0.1-
^TRFAM MO ^OQ APTUA! ^-
OIlltMIVI tii
EFFECTIVE HEIGHT OF EMISSION WIND SPEED s,V.!*'. 10 1. '"""""« s°'" ««"•"••" '"«'» o.«-«« ^ EM'SSIO'J
( merer)
(m/sec)
m itc * ' Pj
(miles/hr) < 2 A AS B (g/sec)
23 AB B C E F
35 B 8C C D t
VTE xm°r xp
(lb/hr!(mg/m3)
S6 C CO 0 0 D
» 6 C D 0 D D
Tt
-------
3. The chlorolysis process, where carbon tetrachloride and anhydrous
hydrogen chloride are produced recovering virtually all the carbon
chlorine, and hydrogen values.
Chlorolysis Process
Chlorolysis is a recycling process for which byproduct residues of
various chlorination processes may be used as feed in order to convert them
into products that may be utilized again, that is, to carbon tetrachloride
and anhydrous hydrogen chloride (which can also be absorbed in water and
sold as muriatic acid).
This study is based on feedstock residues obtained from VCM-production
and the production of solvents containing chlorine, e.g., perchloroethylene.
Chlorolysis itself produces only a small quantity of byproducts, since
the space time yield and the conversion (95%) are highly efficient. All
chlorolysis byproducts, that is those components which have not been
completely converted to HC1 and CCli^, are recycled to the reactor to
extinction. Carbonyl chloride is obtained as an unwanted byproduct if the
feedstocks contain oxygen. Carbonyl chloride is burnt together with those
blowdown tars that are left over from pretreatment of the feedstock residues.
The chlorolysis plant is provided with an absorption unit for the
removal of chlorine and hydrogen chloride gas in case of emergency and for
normal startup and shutdown of the plant. This unit consists of three
stages, which assures that the environment remains unaffected.
Incineration Unit
As described previously, all pretreatment chlorinated tars that cannot
be used in chlorolysis are burnt, together with all wastewater streams
contaminated with traces of chlorinated hydrocarbons.
During incineration, HC1, CO2, and H20 are formed and, in case of
improper functioning of the unit, also traces of chlorine. The hydrogen
chloride is absorbed from the off-gas in a way that the environmental
regulations are observed (See Figure 8).
For specification of the stack height, a C12 or HC1 concentration value
for off gases from the absorber C-302 was assumed which was unfavorable by a
factor of 10. According to the nomograph contained in an EPA report
entitled "Estimation of Permissible Concentration of Pollutants for
Continuous Exposure,"3 using the specified stack height of 40 m, the actual
value emission rate Q = 0.58 g/sec (with a safety factor of 10) was still
below the permissible value Q = 1 g/sec.
39
-------
SECTION 7
ECONOMIC ANALYSIS
1. The costs and economics presented herein are based on a new plant
location with a clear and level site in the Gulf Coast area. It is also
assumed that foundations can be installed with conventional spread
footings and that a pumping station is not required to provide cooling
water to the plant.
2. The basis of a new plant location significantly affects the economics of
the chlorolysis plant. It should be recognized that the economic
criteria presented in this study would be improved substantially if the
chlorolysis plant were installed as part of an existing chlorocarbon
chemical production complex.
3. The study is based on plant erection during the first half of 1977. No
forward escalation has been included for possible increased or decreased
costs from that time. It is estimated that approximately two and
one-half years would be required to erect the plant from the time of
contract award.
4. The economic criteria is based on a plant location that would be central
and convenient to those plants producing vinyl chloride monomer and
chlorinated solvent wastes. This condition exists in both the New
Orleans and Houston areas. In either case the collection and
transportation of the waste to the regional chlorolysis plant would be
minimal.
5. The cost summaries presented in Tables 4 and 5 correspond to operation at
the design feed capacity for the base (mixture I) and 100% VCM residue
(mixture II) feed cases, respectively. Nominal values for both the
carbon tetrachloride selling price and residue disposal toll charge of
$300/MT and $75/MT, respectively, were assumed for these analyses.
6. The sensitivity of plant economics to assumed carbon tetrachloride value
and toll charge for each feed case is summarized in Table 6 and plotted
in Figures 12 and 13. The assumed carbon tetrachloride value ranged from
$275/MT to $325/MT. Based on a cursory examination of the projected
market, this range seems appropriate, but a more detailed analysis would
be necessary at a later date for a precise economic .evaluation.
Similarly, the assumed toll charge range was $25/MT to $125/MT. As seen
from Figures 12 and 13, the plant economics are not as sensitive to toll
40
-------
TABLE 4. ECONOMIC EVALUATION SUMMARY
Base Case (Mixture 1) Feed Residues
BASIS 25,000
Raw Materials
C12
Caustic (20%)
Methane
Utilities
Power
Steam (HP + LP)
Cooling Water
Operating Cost
MT/yr 75,000 MT/yr CClk Product
Total Fixed
Process Royalty
Working Capital
Total Fixed Royalty & Working
Annual Quantity Unit Price
68,000 MT $125/MT
14,500 MT $30/MT
134,500,000 ft3 $2/1000 ft3
Total Raw Material Cost
25,600,00 KWH $0.015/KWH
52,000 MT $4/MT
3.9 x 109 gal. $0.01/1000 gal.
Total Utility Cost
Men/Shift Total
•
Labor 10 44
Supervision
Maintenance, 4% Fixed
Total Operating Cost
Overhead Expense
Direct Overhead 30% Labor & Supervision
General Plant Overhead 50% Operating Cost
Insurance, Property Taxes 1.5% Total Fixed
Depreciation 10% BLCC & 5% Offsite
Interest 10% Working Capital
Total Overhead
Process Royalty Over
Ten Years
Total Production Cost
for First Ten Years
Product Cre
-------
TABLE 4. ECONOMIC EVALUATION SUMMARY (continued)
Base Case (Mixture 1) Feed Residues
Waste Credit
Annual Quantity
Unit Price
(Toll for Waste Removal)
Chlorocarbon Waste 25,000 MT
ROI
ROR
Payout
(After Tax Income)
(Total Fixed + Work)
(Cash Flow)
(Total Fixed + Work)
(Total Fixed)
(Cash Flow)
$75/MT
Total Product & Waste
Credit
GROSS INCOME
AFTER TAX INCOME
DEPRECIATION
CASH FLOW
16.4%*
24.2%
3.75 yrs
Annual Income
$ 1,875,000
$25,267,500
$ 9,217,500
$ 4,608,750
$ 2,175,000
$ 6,783,750
*These percentages are based on royalty paid over ten-year period after which
return/rate would improve.
42
-------
TABLE 5. ECONOMIC EVALUATION SUMMARY
100% VCM Residue Feed (Mixture II)
BASIS 25,000
Raw Materials
C12
Caustic (20%)
Methane
Utilities
Power
Steam (HP + LP)
Cooling Water
Operating Cost
MT/yr 88,500 MT/yr CCl^ Product
Total Fixed
Process Royalty
Working Capital
Total Fixed Royalty & Working
Annual Quantity Unit Price
93,800 MT $125/MT
14,500 MT $30/MT
134,500,000 ft3 $2/1000 ft3
Total Raw Material Cost
25,600,000 KWH $0.015/KWH
52,000 MT $4/MT
3.9 x 109 gal. $0.01/1000 gal.
Total Utility Cost
Men/Shift Total
Labor 10 44
Supervision
Maintenance, 4% Fixed
Total Operating Cost
Overhead Expense
Direct Overhead
General Plant Over he
Insurance, Property
Depreciation
Interest
Product Credit
CCltj
HC1 (100%)
30% Labor & Supervision
sad 50% Operating Cost
Taxes 1.5% Total Fixed
10% BLCC S 5% Offsite
10% Working Capital
Total Overhead
Process Royalty Over
Ten Years
Total Production Cost
for First Ten Years
Annual Quantity Unit Price
88,500 MT $300/MT
30,000 MT $50/MT
Product Credit
$25,496,900
3,500,000
2,549,690
$31,546,590
Annual Cost
$11,750,000
435,000
269,000
$12,454,000
$ 383,000
208,000
39,000
$ 630,000
$ 761,000
97,000
1,020,000
$ 1,878,000
$ 258,000
939,000
381,000
2,175,000
255,000
$ 4,008,000
$ 350,000
$19,320,000
Annual Income
$26,550,000
1,500,000
$28,050,000
43
-------
TABLE 5. ECONOMIC EVALUATION SUMMARY (continued)
100% VCM Residue Feed (Mixture II)
Waste Credit
Annual Quantity
Unit Price
(Toll for Waste Removal)
Chlorocarbon Waste 25,000 MT
ROI
ROR
Payout
(After Tax Income)
(Total Fixed + Work)
(Cash Flow)
(Total Fixed + Work)
(Total Fixed)
(Cash Flow)
$75/MT
Total Product & Waste
Credit
GROSS INCOME
AFTER TAX INCOME
DEPRECIATION
CASH FLOW
18.9%*
26.7%*
3.4 yrs
Annual Income
$ 1,875,000
$29,925,000
$10,605,000
$ 5,302,500
$ 2,175,000
$ 7,477,500
*These percentages are based on royalty paid over ten-year period after which
return/rate would improve.
44
-------
TABLE 6. SUMMARY OF RESULTS OF ECONOMIC CALCULATIONS FOR BASE AND
MIXTURE II (100% VCM Residue) Feed Cases
Ui
Selling price Toll charge
CCljt, $/MT waste, $/MT
BASE CASE
275
300
325
275
300
325
275
300
325
MIXTURE II
275
300
325
275
300
325
275
300
325
75
75
75
25
25
25
125
125
125
(100% VCM Residue)
75
75
75
25
25
25
125
125
125
ROI, %
13.1
16.4
19.7
10.9
14.2
17.5
15.3
18.6
22.0
CASE
14.9
18.9
22.9
12.5
16.7
20.6
17.2
21.1
25.1
ROR, %
20.7
24.2
27.5
18.6
21.9
25.4
23.1
26.5
29.7
20.5
24.5
28.4
20.5
24.5
28.4
25.0
28.9
32.8
Payout, Discounted
yrs cash flow, %
4.4 13.0
3.8 16.0
3.3 18.2
4.9
4.1
3.6
3.9
3.4
3.1
4.0 15.0
3.4 18.0
3.0 21.0
4.4
3.7
3.2
3.6
3.1
2.8
-------
charge as carbon tetrachloride price. Nevertheless, it would be
necessary to negotiate contracts for these charges with waste producers
before proceeding with construction of a regional chlorolysis plant.
As can be seen from these calculations, the adjustments to the economics
analysis which may be necessary for a specific location or situation can be
either additive or deductive. In general, it can be expected that all of
these factors would tend to balance out. Therefore, the net result is such
that the economics, as presented herein, are sufficiently accurate and
representative to be used for future planning purposes.
With regard to the results of this analysis, if one uses the nominal
carbon tetrachloride value and toll charge above, it can be seen that the
return on investment (ROI) ranges from about 16% to 19%. Similarly, the rate
of return (ROR), which includes credit for depreciation, corresponds to
approximately 24% to 27%. Finally, the discounted cash flow is in the range
of 16% to 18% for the same conditions. (Return on investment and rate of
return are defined in Tables 4 and 5.)
46
-------
REFERENCES
1. Disposal of Organochlorine Wastes by Incineration at Sea. EPA-430/9-75-
104, U.S. Environmental Protection Agency.
2. Shiver, J. Converting Chlorohydrocarbon Wastes by Chlorolysis. Repro
Chemical Corporation. EPA-600/2-76-270, U.S. Environmental Protection
Agency, Washington, DC.
3. Handy, R. and A. Schindler. Estimation of Permissible Concentrations of
Pollutants for Continuous Exposure. Research Triangle Institute. EPA-
600/20-76-155, U.S. Environmental Protection Agency, Research Triangle
Park, NC. 1975.
47
-------
APPENDIX A
DESIGN SPECIFICATIONS
SPECIFICATIONS OF RAW MATERIALS, UTILITIES AND AUXILIARIES
Raw Materials
Chlorine (liquid)
Chlorine
Water
Nitrogen trichloride
Hydrogen
Oxygen
Carbon dioxide
Mercury
99.5% minimum
<60 wt ppm
unknown
<50 wt ppm
<1500 wt ppm
<5 wt ppm
negligible
Note: This specification was given by Repro3 and was used as the basis for
all material balances. It would be preferable to use chlorine with a
maximum 20 ppm H20 and 50 ppm 02.
Utilities
Steam—
Steam (high pressure) saturated
Steam (low pressure) saturated
Cooling Water—
Supply
Temperature, summer conditions
Pressure
Return
Pressure
Fouling factors
BL
BL
200 psig
15 psig
90°F
60psig
100°F
to be set by pressure drop of users
0.0002-0.005
0.0004-0.001
hr-ft2-°F
BTU
kcal
48
-------
Fuel
Natural Gas—
The United Gas Pipeline Company of Jackson, Mississippi, would provide
natural gas for the facility. The specification for this gas is as follows:
Fuel Value - 1.035-1.039 BTU/cf—
Hydrogen
Oxygen
Carbon monoxide
Carbon dioxide
Methane
Propane
Nitrogen
Ethane
Isobutane
n-Butane
Pentane
H2S 0%
Sulphur
Humidity
Pressure
NGPA charcoal test
Electric Power—
Conditions at the BL of the plant:
1. Frequency: 60 Hz
2. Power receiving voltage: 13.800 kV
3. Equipment voltage: 500 V and 13.800 kV
4. Lighting circuit voltage: 208 V
5. Short circuit capacity on the side 13.8 kV: 200 MVA
6. Feeding of power and lighting users from common transformers
7. Voltage of electric motors Capacity up to 200 kW: 500 V
Larger than 200 kW: 13,800 V
8. Voltage variation from nominal not more than ± 5%, in case of emergency
+ 10%
9. Frequency variation: + 1%, in ease of emergency + 5%
10. Emergency power will be supplied to maintain safety operation or
execute safe shutdown
5% by mol.
0% by mol.
0% by mol.
0.82% by mol.
96.13% by mol.
0.27%
0.31%
2.32%
0.06%
0.06%
0.03%
0.01 g/100 cf
<7 lbs/1,000,000 cf
60 Ibs delivered
0 gal./I,000,000
Nitrogen—
Oxygen content
Oil content
Dew point
Pressure
C02 content
maximum 20 wt ppm
absent
-55°C
35 psig
not detectable
49
-------
Plant Air—
Pressure 85 psig
Dew point -9°C (during summer)
Oil content absent
Instrument Air—
Pressure 85 psig
Dew point -30°C
Oil absent
Auxiliaries
Ammonia—
Conditions at BL, tank storage or bottles.
Caustic Soda—
Conditions at BL 30% or 50% by wt
Pressure 50 psig
Silica Gel
Specifications—
Si02 99.8% by wt
SizOs 0.01%
A1203 0.03%
Ti02 0.03%
Na20 0.02%
CaO 0.04%
Traces of other elements 0.04%
Physical Properties—
Specific gravity 2.2 g/cm3
Bulk density 750 g/1
Specific surface 800 m2/g
Size 3-4 mm
Heat Transfer Medium - Dowtherm A—
Boiling point 575°p
Melting point -18°F
Density, lb/ft3 at boiling point 55
Refrigerant R-12
50
-------
Local Potable Water
(Henry Speir, Laboratory Technician, National Aeronautics and
Administration, Bay St. Louis, MO, 601/688-2000. 9 June 1976.)
Space
Analysis
Silica
Iron 0.02
Manganese
Calcium
Magnesium
Sodium
Potassium
Bicarbonate
Carbonate
Sulfate
Chloride
Fluoride
Nitrate
Dissolved solids
Total phosphorus
Tripen (Hexachlorobutadiene)
ppm
19.00
0.10
3.70
0.50
91.00
1.10
194.00
11.00
17.00
12.00
0.30
0.60
252.00
50.00
As lubricate for chlorine high pressure pump
reboiler E-522.
P-402 and heating agent for
Specification
Molecular weight
Specific gravity at 20°C, kg/1
Melting point, °C
Boiling point at 760 mm Hg, °C
Specific heat at 22°C, kcal/ck°C
Viscosity, cp, 15°C
Viscosity, cp, 21°C
Viscosity, cp, 50°C
Viscosity, cp, 98°C
Thermal conductivity at 22°C,
kcal/mhr °C)
Technical Grade
260.8
1.68
-18
212
0.202
9.22
3.68
2.40
1.13
0.087
PRODUCT SPECIFICATION
Final Product
Specification—
Carbon tetrachloride
Impurity (maximum)
Humidity
Free chlorine
minimum 99.9% by wt
35 ppm wt
10 ppm wt
51
-------
Non-volatile residue
Acidity (HC1)
Tr ichloroethylene
Perchloroethylene
Hexachloroethane
Other additions
(by gas chromatography)
Maximum color
Iodine index
Specific weight at 25°C
Distillation limits
Byproduct
Hydrogen Chloride (gaseous)
Analysis
HC1
Impurities (maximum)
Chlor ine
Carbon tetrachloride
Carbonyl chloride
Moisture
6 ppm wt
10 ppm wt
100 ppm wt
50 ppm wt
10 ppm wt
100 ppm wt
5 APHA
negative
1.582-1.590
not more than 1°C
minimum 99% by wt
100 ppm wt
50 ppm wt
50 ppm wt
100 ppm wt
WASTE STREAMS (See Figures 2, 3, and 6 of Volume I)
Waste Gas (Stream Numbers refer to HUC Drawing Number B-10400-7 in Volume II)
Stream Number
206
255
309
605
538
607
Amount, kg/h
6
6
2851
maximum 4334
1250
10
7475
Composition
leakage air, traces of heavy ends
leakage air, traces of solvents
inerts 96 wt %
H20 4 wt %
inerts
Cl2 maximum 10 vol. ppm
COC12 maximum 10 vol. ppm
CClit maximum 10 vol. ppm
inerts
CClit maximum 50 wtr ppm
COC12 maximum 1 wt ppm
HC1 maximum 3 wt ppm
N2 72.9 wt %
H20 10.6 wt %
02 3.7 wt %
C02 12.8 wt %
SO2 0.4 wt ppm
52
-------
Waste Water (Stream Numbers refer to HUC Drawing Number B-10400-7 in Volume
II)
313 14,000 NaCl 5 wt %
Normal Maximum
606 normal 40 H20 90 wt % 80 wt %
maximum 50,000 NaOH 5-10 wt % 16 wt %
in case of NaOCl 2 wt % 1 wt %
emergency NaCl 2 wt % 1 wt %
NazCOs «0.1 wt % 0.1 wt %
CCli+ - 0.8 wt %
Heavy ends - 0.2 wt %
CONSUMPTION FIGURES
The expected consumption figures for raw materials, chemicals, and utilities
for the chlorolysis and incineration plant, based upon 1,000 kg of feedstock
residues, are as follows:
Raw Materials and Chemicals
Chlorine (100%) 2723 kg (base case)
3943 kg (maximum, case III)
NaOH (20%) 580 kg
Utilities
Power 640 kWH
Cooling water, At = 5°C 580 m3
Steam, 15 psig 1150 kg
Steam, 200 psig 960 kg
Natural gas, 9210 kcal/Nm3) 152 Nmd
Nitrogen 16 Nm
Instrument air 654 Nm
Atomizing air 160 Nn^
Condensate 0.15 m
Process water * m
The above utility figures do not include minor consumption in the auxiliary
units such as waste HC1 treatment or cooling tower operation, etc.
53
-------
30 -
28 -
26 -
24 -
;22 -
20 -
18 -
22
20
18
16
16 -
270 280 290 300 310 320 333
SELLING PRICE
CCU, '$/MT
Figure A-l. Sensitivity of chlorolysis plant economics to carbon
tetrachloride price and disposal toll charge (base
feed mixture).
54
-------
34
32
26
24
30
28
26
24
22-
22
20
13
16
14
20-
12
18
270 280
290 300
SELLING PRICE
CC1,,, S/MT
310 320 333
Figure A-2.
Sensitivity of chlorolysis plant economics to carbon
tetrachloride price and disposal toll charge (100%
VCM residue feed).
55
-------
TECHNICAL REPORT DATA
(Please read Instructions on the reverse before completing)
1. REPORT NO.
EPA-600/2-78-146
3. RECIPIENT'S ACCESSION NO.
4. TITLE AND SUBTITLE
Chlorolysis Applied to the Conversion of
Chlorocarbon Residues
5. REPORT DATE
July 1978
6. PERFORMING ORGANIZATION CODE
c.E.Shannahan, H.Weber, G.Hauptman,
and N. Carduck
8. PERFORMING ORGANIZATION REPORT NO,
9. PERFORMING ORGANIZATION NAME AND ADDRESS
Hoechst-Uhde Corporation
560 Sylvan Avenue
Englewood Cliffs, New Jersey 07632
10. PROGRAM ELEMENT NO.
1BB036
11. CONTRACT/GRANT NO.
68-03-2380
12. SPONSORING AGENCY NAME AND ADDRESS
EPA, Office of Research and Development
Industrial Environmental Research Laboratory
Research Triangle Park, NC 27711
13. TYPE OF REPORT AND PERIOD COVERED
Final; 12/76-3/78
14. SPONSORING AGENCY CODE
EPA/600/13
15. SUPPLEMENTARY NOTES EPA project officers are M.Samfield (TERL-RTP) and R.V.
Swank (ERL-Athens).
16. ABSTRACT
The report gives results of a study to determine the technical and economic
feasibility within the U.S. of eliminating the discharge of large quantities of chloro-
carbon residues, which are harmful to the environment. The Chlorolysis Process,
used on pilot scale in West Germany for nearly 10 years on almost identical
residues, has produced saleable products. The concept involves a centrally
located conversion plant which would collect discharges from several nearby pro-
ducers of chlorocarbon residues in order to reduce transportation and processing
costs. Based on information from a previous EPA report, it appears that such a
plant could be located in either the Houston or New Orleans area, where from one-
fourth to one-third of the total amount of such residues now being produced could be
converted to carbon tetrachloride. A nominal rate of return of 24.2%, after taxes,
is indicated, based on typical utility and consumption figures, including credits for
chemicals produced. The process is licensed by Hoechst AG (FDR), through Hoechst
-TJhde Corporation (USA). A large commercial plant (50,000 metric ton/yr) incor-
porating this technology started up in 1977. In addition to its established basis,
the Chlorolysis Process can handle a wide variety of chlorocarbon waste residues,
making it especially suitable for a regional plant.
17.
KEY WORDS AND DOCUMENT ANALYSIS
DESCRIPTORS
b.IDENTIFIERS/OPEN ENDED TERMS
c. cos AT I Field/Group
Pollution
Chlorination
Chlorine Organic
Compounds
Chlorohydrocarbons
Residues
Waste Treatment
Carbon Tetra-
chloride
Pollution Control
Stationary Sources
Chlorolysis
Chlorocarbons
13B
07C,07B
3. DISTRIBUTION STATEMENT
Unlimited
19. SECURITY CLASS (ThisReport)
Unclassified
21. NO. OF PAGES
62
20. SECURITY CLASS (Thispage)
Unclassified
22. PRICE
EPA Form 2220-1 (9-73)
56
------- |