JPS5811080A - Method of washing inside of vessel - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION This invention relates to a method for cleaning containers, particularly containers used for the storage and/or transportation of chemicals and the like, in an environmentally and economically acceptable manner. More particularly, the present invention cleans the interior of containers with a solvent, recovers the contaminant-containing solvent for subsequent reuse, and cleans the contaminant-containing solvent for subsequent reuse;
RR41 relates to a method for cleaning the interior of containers contaminated by chemical residues.

When cargo is transported by road using tank cars, transported by rail using tank wagons, packed into tanks by ships or berths, and then packed into drums before being transported by water, residual chemicals are removed from inside the tanks. It is possible to sufficiently remove
In some cases it is generally desirable and even necessary. Cleaning of the tank is especially necessary if you are going to fill it with a different cargo than the previous one. This is because it is necessary to ensure that the cargo is not contaminated by iU residue remaining in the tank from the previous time. Such tank cleaning is also carried out before tank repair or testing.

It is estimated that there are probably several hundred types of cargo handled by tank wagons, tank cars, and drums, perhaps in the thousands. Tanks, some tank cars and drums are generally used in dedicated 141 service (carrying only one type of cargo) and are washed only before repair or testing unless they become contaminated. Non-dedicated tank cars and drums are cleaned after each shipment to prevent cross-contamination. It is estimated that approximately 37,000 tank wagons, 5,000,000 tank cars and 25,000,000 drums are cleaned annually (U, S, Departm).
entof Commerce, National
Technical Information S@rv
ie@PB-280726”SourCaAsaess
ment! Ra1l Tank Car, Tank
Truah, and Prum Cleaning,
5tate of theArt"by Mon5a
nto Research Corp, Dayton.

0h1o, April mouth, 1978 Kl Teru).

Due to the wide variety of chemical residues that must be removed from these tanks, it is extremely difficult to design and operate a single tank cleaning station capable of handling such residues. be.

Generally, cleaning agents such as water, water, detergents, and bath additives are used in such methods of cleaning tanks. These cleaning agents are generally applied using steam hoses, pressure rods, and rotating jet heads placed through openings in the containers. Scraping and scraping of hardened or crystallized contaminants is often necessary. Vapors emanating from tanks used to store volatile materials would be sent to the cleaning equipment flare. Vapors of substances such as anhydrous ammonia and salt solution dissolve in water to form waste hydroxide. Not processed by flare,
Also, vapors 1d that do not dissolve in water are released into the atmosphere.

Steam cleaning and/or water flushing of tank wagons, tank cars, and drums generally involves airborne splashing and the discharge of contaminated wastewater. Both organic and inorganic vapors are released into the air by washing tanks and tank cars. Contaminated water from washing tank wagons, tank cars, and drums primarily contains oil, grease, and high lv element demand (COD).
substances, suspended solids and toxic or toxic substances.

According to EPA calculations, 215 tank truck industries discharge wastewater into streetcar facilities with little or no pretreatment. Where pretreatment is available, it is generally limited to sedimentation, neutralization, and evaporation treatments in bonds or lagoons.

Until the late 1960's, little attention was paid to the treatment of wastewater from washing tank wagons, tank cars and drums. This lack of attention was primarily due to the fact that the amount of wastewater is generally small, the equipment is small, and the impact it has on the environment.
This is because the amount of pollution caused by pollution was considered to be relatively small compared to other sources of industrial pollution.

As already indicated, the wastewater from two-thirds of the system is directed to the tram treatment system, and the rest is discharged into the surface water stream, possibly after some oil separation treatment.

In recent years, the tank cleaning industry has made efforts to increase waste processing capacity. There is no known device with a fully satisfactory processing system. Most of the processing techniques at an applicable level are well known and have been used by @ZoKogyo for several years. Due to the wide range of types of residues to be removed and the diversity of effluent wastes, it has been considered impractical to use a single specific device and method for cleaning.

For this reason, tank car cleaning companies have approached the problem of cleaning and contaminant treatment individually by using a combination of several methods.

However, to date, there is no single practical and economical method to effectively clean and reduce emissions from tank wagon and tank car washing operations.

Many methods and devices have been developed for cleaning containers such as tank wagons, tank cars and drums. See, for example, the following US patent:

4.106,950 Grlimer
) 1977, 10.283.434.881 Smith 1969.5.253.2
s 1,269 Watts
1966, 10.253.188,238 Lyon 1965.6.83.046,
163 Kearney et al.
) 1962, 7.24 3.042,553 Kearney et al.
et al) 1962, 7.3 3.053.215 Mirror (M1st, or)
1962.5.8 Ro, 025, 190 Groom et al. 1962.3.1
3 3.944,924 Sven-Erik Rijklundh et a
l) 19<SO, Otsu 12 2.092,321 Macfaden 193
7.9.7 (McFaddsn) 2.065,462 Olson (Olason)
1936.12.222.045,752 Butterworth 1936.6.30 (But
terworth) 1.816,954 Byerley
) 191.8.41.722, 211 Guardlno 1929.7.23 However, no prior literature clearly describes environmentally and economically acceptable methods for removing chemical residues from containers. do not have.

Several methods for recovering and reusing solvents have been described in general terms. See, for example, the Grismer and Smith patent. However, they do not describe a particularly economically and environmentally acceptable recovery method that takes into account the wide range of rod chemical residues or contaminants in the solvent.

Other documents describe the use of complex equipment to scour the interior of tanks. For an example, see Watt's patent.

Other documents describe the use of portable cleaning devices to clean tanks during transport. See, for example, the Rion patent. However, nothing is said about the treatment of waste illumination from such cleaning methods.

Other methods have been described, such as the use of chlorinated hydrocarbon solvents to clean the interior of tank streams. See, eg, the Carney et al. patent. These methods are
DI requires complicated heating and injection equipment.

Furthermore, most literature calls for transliterating specific solvents to remove specific chemical residues and uses those solvents multiple times.

The inventors have now discovered an economical and cost effective method for cleaning the interior of containers.

According to the method of the invention, the interior of containers is cleaned with a solvent and the solvent containing contaminants is recovered from the containers. and treating the contaminant-containing solvent to form a combustible contaminant composition with the pure solvent, wherein the pure solvent is reused and the contaminant composition is disposed of in a trivial manner by incineration thereof. Process in the state of being edicted.

In accordance with the invention, the interior surface of the container is contacted with a contaminated solvent to remove at least a portion of the contaminant to obtain a contaminated solvent, and the contaminated solvent is collected from the container. It is proposed a method for removing contaminants from the interior surfaces of containers, which comprises separating substantially all of the contaminants from the contaminant-containing solvent, thereby obtaining an incinerable contaminant composition. Ru.

The solvent used in the method of this invention is one that is liquid at ambient temperature and capable of removing contaminants present in the particular container to be cleaned.

Solvents generally dissolve contaminants: υ remove contaminants, forming a solvent solution containing the contaminants, but also remove contaminants by suspending the contaminants in the solvent. be able to.

The solvent used is further one that can be substantially completely separated from contaminants by at least one of several standard separation techniques, such as distillation, liquid-liquid extraction, combination thereof, and similar methods. It is.

Solvents that can be used in the practice of this invention include, but are not limited to:

1. Chlorinated liquid aliphatic compounds (typically lower aliphatic compounds), such as medelene chloride, trichloroethane, trichloroethylene, ethylene dichloride and hyber-chloroethylene.

2. Liquid aromatic compounds and solvents (monocyclic in lμ type), such as benzene, monocyclic alkylated aromatic compounds (toluene, o'-, m"-, and/or p-xylene, ethylbenzene, etc.) ), hydroxy aromatic compounds (phenol, o-, 7fe and/or 1m-cresol and cresyl m, etc.), benzyl compounds, labor group amines (aniline, etc.), bitter aromatic ethers (anisole, etc.), chlorinated aromatics compounds (e.g. 0-dichlorobenzene), nitrated aromatics, and bicyclic aromatics (e.g. pyridine)
.

6. Lower alkanones, such as acetone, methyl ethyl phthone, cyclohexanone, and zatone.

4 Aldehydes, such as benzaldehyde, acetaldehyde, etc.

5. Sulfoxide moe, such as dimethyl sulfoxide.

6 Organic acids, such as sulfonic acids and lower carboxylic acids such as formic acid, lauric acid, myristic acid, acetic acid and propionic acid.

Z aliphatic amines such as mono-, di- and tri-,
Alkanolamines such as ethanolamine.

8. Aliphatic alcohols, such as methanol, ethanol, glopanol (eg mehyisoglobanol), butyl alcohol anti-hifusel oil.

9. Solvents with or without non-aromatic 5-ring and 61, carbocyclic and bicyclic capping groups: 4: such as cyclohexanone, dioxane, etc.

10. Ethers, such as dibuchetyl.

11. Esters, for example esters of carboxylic acids such as ethyl acetate.

12. Coal or petroleum distillates, such as petroleum ether, benzene, naphtha, Stoddard solvent
s aobvent).

Mixtures of these solvents, reaction products and solvents such as organic carboxylic acids can also be used.

However, this is limited to cases where these products or mixtures have sufficient dissolving power, are liquid at moderate ambient temperatures or at room temperature, and have a viscosity suitable for pumping. Salts of solvents, except that they have low vapor pressure and are odorless at room temperature, are not effective, especially for paraffinic and other non-polar residues.

Chlorinated solvents are known to accelerate corrosion when mixed with water under certain conditions, so care should be taken to minimize the presence of water when using chlorinated solvents. I have to pay the border.

Particularly desirable solvents are polar solvents and chlorinated aliphatic solvents.

We have found that perchlorethylene and/or mixtures of perchlorethylene and cyclohexanone are particularly desirable solvents due to their ability to clean a wide range of chemical residues and their safe properties such as high flash points. Ta.

Although perchlorethylene can clean many chemical residues at marginal wetness, we have shown that the cleaning ability of perchlorethylene is enhanced by increasing the temperature above about 50C. At this temperature, bark l
:I+Niaethylene cleans most epoxies, alkyds, and acrylics whose residues are generally considered difficult to clean.

Other types of residues, such as some types of polyesters and phenols, and hydrolyzed isocyanate films can be removed with a mixture of perchlorethylene and cyclohexanone. The ability of the solvent to remove the above-mentioned residues increases as the mixing ratio of chlorhexanone and chlorhexanone increases.

It has been found that a mixture of perchlorethylene and cyclohexanone in a volume ratio of about i/40 to 50,150 removes almost all of the residue, and that a solvent with a volume ratio of 50,150 is desirable.

Perchlorethylene, one of the preferred solvents of this invention, has no flash point and has a flash point of 160"F (711
:) Holds higher. When containing perchloroethylene and cyclohexyl mixed polyester phenols at a volume ratio of 50,150, the flash point is approximately 110 to 13,077 (
50,2-54C) Tonal. Although mixtures of perchlorethylene and cyclohexanone are themselves nonflammable, they are generally unable to maintain a high flash point for high-melt mixtures of low flash point organics. For this reason, prior to cleaning or rinsing the tank using this mixed solvent, cleaning or rinsing the tank using e.g. It is desirable, but not essential, to extract organic matter.

In order to maintain the high cleaning capacity of the solvent and/or to maintain the flash point as high as possible (preferably above 160'F), it is necessary to maintain the concentration of residue in the solvent below a certain value. . It has been found that for perchlorethylene, it is desirable that the double distillate confusion is about 25% by volume or less. For a mixed solvent of perchlorethylene and cyclohexanone with a volume ratio of 5015[], it is desirable that the residue concentration be less than about 25% by volume. When the residual temperature reaches the above values, it is desirable to treat and recover the solvent by the method of the present invention.

A major advantage of the tank cleaning method of this invention is that it is environmentally sustainable. Solvents should be extracted and reused only to the minimum extent necessary, vapors from the bag presses 1 should be captured and disposed of in an environmentally acceptable manner, and chemical residues should be properly removed using environmentally acceptable methods. to be processed.

The method of recovering organic solvent from the solvent used for cleaning and treating the residue is useful not only in the method of the present invention for tank cleaning, but also as a method for replenishing certain solvents from certain compositions in general. I found that.

Generally, the solvent composition contains, for example, this light A1.
1l Desired solvents listed in section 1 of the solvent (1)
In particular, chlorinated aliphatic solvents such as methylene chloride, trichloroethane, l-lichloroethylene, ethylene dichloride and perchloroethylene) and I2J
Sweet Solvent It is not only difficult and expensive to subject these solvent compositions to distillation alone, but also
It has been found that the mixture E7 with the desired solvent is also unsuitable for separating the desired solvent from contaminants, such as the formation of contaminants.

One embodiment of the method of this invention for separating the desired solvent from a contaminated solvent composition containing the desired solvent and tI3 dye consists of the following steps.

(a) Distilling the solvent composition to obtain can residue and overhead product.

The overhead product contains at least some contaminants and the desired solvent.

(b) Contacting the overhead product with an effective amount of sulfuric acid to remove most of the contaminants to obtain 1" dredged spent sulfuric acid containing the desired solvent and removed contaminants.

e→ Substantially neutralize the acidified desired solvent and recover the desired solvent.

Suitable disclosure devices W are well known in the art. For example, perchlorethylene distillers have been used for a long time. Obtain bottoms and overhead product. An overhead product is obtained upon exposure of the solvent containing contaminants. Usually this will include some contaminants such as polar contaminants such as chemical residues and the desired solvent such as perchlorethylene.

The overhead product is then sent to a liquid-liquid contacting system where it is contacted with an effective amount of sulfuric acid to remove most of the contaminants. The sulfuric acid is concentrated sulfuric acid, preferably at a concentration of about 85% or greater, and preferably about 96% or greater to minimize corrosion problems. Sulfuric acid reacts with and/or absorbs contaminants. Two layers are formed during this contacting step. an upper layer comprising an acidified solvent, such as an acidified perchloroethylene composition;
This is a spent sulfur layer. The spent sulfuric acid layer contains contaminants extracted from the overhead product.

By exposing the contaminated solvent containing a mixture of perchlorethylene and cyclohexanone, an overhead product containing recovered perchlorethylene and cyclohexanone is obtained. This overhead product can be reused as is if the content of contaminants is relatively low. However, if the level of contaminants or degree of decomposition is too high for use, it may be sent to a liquid-liquid contactor for contact with sulfuric acid.

Generally, cyclohexanone cannot withstand contact with sulfuric acid, so if a mixture of cyclohexanone and perchlorethylene is subjected to direct acid contacting, most or all of the cyclohexanone will be lost.

Therefore, it is desirable to do the following. That is, first, cyclohexanone is separated from the mixed solution by a method such as fractional release. The remaining portion of the solvent mixture consisting primarily of perchlorethylene containing contaminants is then contacted with sulfuric acid. The contaminant-free perchlorethylene recovered from the sulfuric acid can then be remixed with the exposed cyclohexanone to form a contaminant-free mixed solvent suitable for reuse.

If solvents containing contaminants are exposed, the can residue may exhibit high viscosity. Therefore, embodiments of the invention include adding a flammable diluent to the can residue. The diluent can be injected from the fish oil unit into the pipeline transporting the can residues, or directly into the release unit itself.

Direct addition of diluent to the total distillation unit reduces the viscosity of the bottoms, avoids solidification of the residue, and reduces the concentration of desired solvents in the overhead product, such as perchloroethylene, as well as cycloproethylene and cyclohexanone. The yield of the mixture is improved. Also, can residue has no fuel value for incineration.

The choice of diluent is highly dependent on the properties of the solvent to be recovered. It is desirable that the diluent remain liquid under rest conditions, ie, have low volatility under open humidity and pressure. However, the main purpose of using a diluent is to keep the can residue fluid, i.e. to enable pumping, and if necessary to provide sufficient fuel value for combustion. be.

Preferred diluents are high boiling hydrocarbons such as fuel oil, mineral oil and naphtha. Particularly desirable for use in tank cleaning processes are fuel oils, especially A2 fuel oils. This is because it provides sufficient heating to evaporate and burn off most other compositions that may be present.

Generally, the range of diluent amounts to be used can be defined as the range effective to fluidize the can residue and avoid solidification and gelation of the can residue under off-season conditions. The appropriate f# tit of diluent to be employed will depend on the nature of the solvent composition being treated, the nature of the diluent employed and the conditions of distillation. Approximately 1Q% based on the volume of the solvent composition to be distilled, approximately 300%
I found that I should use . Desired range is approximately 50%
to about 200%.

The acidified perchlorethylene composition (contaminants removed by contacting the overhead product with sulfuric acid) is substantially neutralized by contacting it with a base. A base can be used that neutralizes the acidified perchlorethylene and does not affect its cleaning ability or decompose the solvent. Preferred bases are alkalis, amines, and carbonates of alkaline earth metals. Alkali hydroxides such as sodium hydroxide, calcium hydroxide, etc. may also be used. but,
A preferred hydroxide is soda ash (sodium carbonate). This is because it is a solid and can be easily removed from perchlorethylene after neutralization. Amines could also be used as bases. A well known amine that can be used and also stabilizes perchloroethylene is N-methylmoboline. However, this base is preferred over materials such as sodium carbonate.

The spent sulfuric acid is desirably coated with a high boiling hydrocarbon such as fuel oil or mineral oil to extract small amounts of residual solvent, such as perchlorethylene, contained in the spent E Cm. Such contacting steps are well known in the art, and equipment and operating conditions for such liquid-liquid contacting will be readily determined by those skilled in the art.

This step 1ii+ll could be carried out in the same equipment as the sulfur 1 ii+ll process or in a separate equipment. The spent sulfuric acid could be brought into contact with air, for example by blowing air, to remove trapped solvent.

The hydrocarbons used to extract perchlorethylene from 1 ton of sulfuric acid can be neutralized and added to the contaminated solvent reservoir as a diluent as described above.

If this hydrocarbon is added directly to the tank as a diluent, at least a portion of the perchloroethylene contained in the hydrocarbon could be recovered in the tank.

For a better understanding of this invention, examples are presented below. However, no specific details or numerical values included in the examples should be construed as limitations unless such details are recited in the claims. All sections and baryanto are 1st grade unless otherwise noted.

Example 1 Distillation of a cleaning solvent containing contaminants and a simulated sample of perchloroedere containing contaminants containing 25% of the chemical by volume in contact with sulfuric acid was prepared.

The composition of this simulated sample is as follows.

Capacity (ml) Perchlorethylene 750.0
2-Ethylhexyl acrylate 45.0 Butyl acrylate 30.0 Isocyanate) (1) 20.0 Styrene 20.0 Fucrate (2) 12.5 Fatty acid (3)
7.5 acetate)”
7.5 Paint (5)
2.5n-dodecyl mercaptan
2.5 Lubricating oil (6) 22.2 Vetrolatum 250
Resin (7)' 70.0 Superactive agent (8' 12
．． 51027.5 Note (1) Mobay Mondun MR, MR8, M
-452, MDI.

Up John Equal volume mixture of PAPI-135 and 390-P (note + no TDI) (2) Equal volume mixture of diethyl ester and dioctyl ester.

(3j Em@ry Emfao 1210.Pa
ndG Tallow 22゜T (erculem P
amak Ta1l Oll 4-47 and Pan
dG Cooonυtt, an equal volume mixture of C-110.

+41 n-amyl ester, butyl ester,
Le: I-, X Equal volume mixture of thyl and hyethyl acetoester.

(5) Pittsburgh Glass Al6-
710. B-16730゜Qulck Pry i>
namel, PPG Multlprlme.

Dupont Topcoat, 'E/5eale
r and Pretr satmant 808-012
An equal volume mixture of.

(61Lubrzol 58.78.890.9')
6.985.1097°13<So, 1395.51
75.3702.3826A, 4426A.

5002, 6401.6705. Exxon Par
onox 12゜15.24, 27, 50, 75, 10
0.165 and Robm and Haag Acry
Equal volume mixture of 704.940+1019.

(7) Equal volume mixture of acrylic resin, epoxy Md 1 lil and alkyd resin.

(8) Robm and Haos Trlton
Equal volume mixture of CF-10, CF-52 and 5F-17.

Fuel oil was added to the above simulated sample of contaminated perchlorethylene. The amount of fuel oil is approximately 25% of the volume of the fuel.

A secular fuel oil of the Citrus family, Genus 2, was used.

Samples containing fuel oil were prepared under atmospheric pressure. The temperature of the can was approximately 1251:1. After regulating under the above conditions, the can residue was collected under reduced pressure.
did.

Pressure Can wetting 1ψ Steam temperature Note 12
6 120 126 110 124 101 124 - 124 Slow oil release 400 95 - Start of boiling 40
0 105 82 400 105 95 400 '106.5 98 Rapid oil release 106 6B 100 69 61 72 67 100 82 74 Rapid oil release 99 87 iio so Slow oil release distillate was analyzed using gas chlorotogelaphy. Chloroethylene was 901%.

At the end of the regime, the can residue contained 6.72% perchlorethylene by weight. The oil exudate after contact with concentrated sulfuric acid contained 96.6*m% perchlorethylene.

A similar solvent sample containing contaminants was heated at 10 On+a.H.
It was enacted in g. The overhead product contained 92.2 pilt% perchlorethylene, and the bottom product contained 3.5 pilt% perchlorethylene.
% perchlorethylene by weight.

The oil exudate after contact with concentrated sulfuric acid contained 975% by weight perchlorethylene.

Example 2゜ Cleaning of solvent with sulfuric acid 10% by volume chemical residue (Example 1 @ see) and 90%
A simulated sample of 1000 m4 of contaminated oil spill perchlorethylene solvent containing approximately 96% perchlorethylene
was contacted with concentrated sulfuric acid.

Mix for 5 minutes to avoid layer separation 1. After that, it was left still. As a result of analysis by gas chromatography, the perchlorethylene layer contained 100% perchlorethylene, including sampling error, and the sulfuric acid layer contained 25% perchlorethylene.

Example 6 Neutralization of Acid-Washed Perchlorethylene A sample of sulfuric acid-washed perchlorethylene was contacted with granular calcium hydroxide. As a result, the acid contained in perchlorethylene was neutralized, and calcium sulfate dispersed in perchlorethylene was precipitated and coagulated. Immediately following this precipitation, the mixture was thoroughly treated with perchlorethylene and N-medelmorpholine to obtain perchlorethylene that could be reused for tank cleaning.

EXAMPLE 4 Distillate Containing Contaminants The sulfuric acid used to wash the perchloroethylene contained varying amounts of suspended perchlorethylene. Analysis of several samples of spent sulfuric acid showed that perchlorethylene ranged from about 0.14 fi to about 7.
It contained % by weight. When spent sulfuric acid was extracted with A2 fuel oil, that is, mixed and allowed to stand, the perchlorethylene ff1U was reduced to about 0.2 to 0.3 N%.

Also, when extracted with naphtha 140, perchlorethylene was reduced to the same level as above.

It was also possible to remove perchlorethylene from spent sulfuric acid by blowing air. Perchloroethylene could then be recovered from the gas phase.

As is clear from the above description, the above objectives are effectively achieved. And since some changes could be made to the above method without departing from the invention, all threatening terms contained in the above description are KI! It should be understood as an example rather than a definitive meaning.

The following is a continuation of page 1. Inventor Barry Alan Friedfeldt 311 Zielton Meadow Ridge, Connecticut 06 484 United States Inventor Saladous John Kaniecki New Chassis 07444 Pompton Plains Bread, United States・Allen Place 2 0 Inventor: John Falton Kennedy 17 Clover Lane, Westport, Connecticut, United States of America 06 880 0 Inventor: John Gutan Liu 3, Demarest Mill Court, West Nyatsuk, New York, United States of America 0 shots Author: Waahed Matsuri Dam, United States of America, Massachusetts 02169, 77 Quincy Adams Place @l! Author: Paul Tan Chen 8392 Huntington Beach Seaboat, California, 92646, USA 0 Inventor: Molton Sternbarb, 870 Old Greenwich Old Wagon Road, Connecticut, USA 0 Inventor: Batamadai Easwaran Narasimpan Burpur Heights B-211 Day 400005 Bonpei, India

Claims (1)

[Claims] 1. (a) bringing the inner surface of the container into contact with a solvent containing the contaminants in the container to remove at least a portion of the contaminants to obtain a solvent containing the contaminants; (b) removing the contaminants; collecting the solvent containing the contaminants from the container, and separating substantially all of the contaminants from the contaminant-containing solvent, recovering substantially all of the solvent substantially free of the contaminants, and incinerating or combustible compositions. A method for removing contaminants from the internal surfaces of a container, comprising obtaining a contaminant composition which can be made incinerated by admixing with a contaminant composition. 2. The method according to claim 1, wherein the solvent is a chlorinated hydrocarbon, a polar solvent, or a mixture thereof. 3. The method according to claim 2, wherein the chlorinated hydrocarbon is perchlorethylene and the polar solvent is cyclohexanone. 4. The method of Section 11r1 for separating at least a portion of the contaminants from the solvent by distillation. 5. The method of claim 4, wherein the combustible composition is added to distillation bottoms. 6. The method according to claim 5, in which the combustible composition is mixed with fuel oil. Z The solvent is a chlorinated hydrocarbon and the contaminants are separated from the contaminant-containing solvent by the steps described below.
+ Scope of Requirement 111A E. 4 (v1) Method. (a) Removal of contaminated solvent (in a sump, can residue, and column containing substantially all chlorinated hydrocarbons) to produce a shellfish product. (b) incinerating the can residue; (c) removing residual contaminants from the chlorinated hydrocarbons by treating the overhead product with sulfuric acid; and (d) washing the chlorinated hydrocarbons. (e) washing the sulfuric acid with a flammable composition to remove residual chlorinated hydrocarbons from the acid; Separation of the agglomerated acids from the sulfuric acid. 8. Returning the neutralized chlorinated hydrocarbon to the first stage of the process and reusing it as a solvent to remove contaminants from the internal surfaces of the vessel. The method according to claim 7. 9. The method according to claim 7, in which the flammable composition used for cleaning sulfur n8 in step (e) is added to the can residue in step (a). 10 Distillation equipment used for distillation of solvents containing contaminants,
The method of claim 9, wherein the combustible composition is added to the can residue by direct injection of the combustible composition. 11. The method according to claim 10, wherein the combustible composition is a fuel oil.