CN101318877B - Process for recycling chloromethane generated in cartap production process - Google Patents
Process for recycling chloromethane generated in cartap production process Download PDFInfo
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- CN101318877B CN101318877B CN2008101225149A CN200810122514A CN101318877B CN 101318877 B CN101318877 B CN 101318877B CN 2008101225149 A CN2008101225149 A CN 2008101225149A CN 200810122514 A CN200810122514 A CN 200810122514A CN 101318877 B CN101318877 B CN 101318877B
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Abstract
The invention discloses a process for reclaiming methyl chloride generated in the production of cartap hydrochloride. The process comprises the following steps of: collecting tail gas containing methyl chloride, which is discharged in the production of cartap hydrochloride; treating the collected tail gas by a separation method of pressurizing and cooling a flow containing methyl chloride to liquefy methanol and dichloroethane, and conducting washing, caustic wash, dehydration and compression to obtain the methyl chloride; and, after compression, reclaiming the methyl chloride in vented gas containing air by a absorbing medium. The whole reclaiming process is environment-friendly due to the realization of clean production and radical elimination of the impact on environment caused by tail gas discharged in the industrial production of cartap hydrochloride. The method has a high absorbing and reclaiming rate, with the mass content of the reclaimed methyl chloride reaching between 99 and 99.99 percent.
Description
Technical field
The present invention relates to the method for purifying and recovering of methyl chloride, more particular is to discharge the tail gas from cartap production to reclaim the method that high yield reclaims the by product methyl chloride through the degree of depth.
Background technology
Clam worm poison derivative pesticide is the bionical sterilant of efficient in one, low toxicity, wide spectrum, and cartap be use the most extensively in these series product, more efficient, the kind that has more broad spectrum, Japanese military field invention and commercialization are arranged the earliest.Domestic have many research units to research and develop since the 60 to 70's, and the progress of achieving no breakthrough property is just confirmed synthesis technique basically until last century end all the time, reaches international standards through nearly ten years continue to optimize at present.See that from the production technique of present domestic cartap most enterprises all adopt desinsection list or disosultap in solvent, to obtain sulphur cyanogen thing with sodium cyanide after hydrolysis, precipitation, separate, dry and obtain cartap, this process recovery ratio is high, quality better.Part enterprise adopts muriate or sulfonated liquid method to produce its yield low, product unstable be prone to rise bag, variable color.
Adopt desinsection list or disosultap and sodium cyanide in solvent, to produce, get into hydrolyzing process and will produce a large amount of tail gas that contains methyl chloride, can be used as the raw material of other Chemicals behind the methyl chloride reclaiming clean wherein.The purification that does not relate to methyl chloride in the hydrolysis tail gas among the preparation method of patent of invention 98111505.5 cartaps is reclaimed; And the manufacturing enterprise of present cartap does not all have the retrieving arrangement of methyl chloride; Restricted by output on the one hand, on the other hand maybe be because recovery did not have rigid requirement to methyl chloride at that time.Methyl chloride tail gas is the general recovery technologies of industry such as careless dried phosphine and organosilicon through washing, technology dry, compression; Only different in dry and purification; Must after compression, discharge because contain air in certain amount in the tail gas, otherwise can in limits of explosion, set off an explosion (the aerial limits of explosion of methyl chloride is 8.1～17.2%), the recovery that therefore liquefies is under some influence; The recovery has only about 93%, in other methyl chloride discharging directly into atmosphere of 7% environment has been caused influence.What produce in the cartap production process contains methyl chloride tail gas component very not identical with Glyphosate 62 IPA Salt (no methylal has increased ethylene dichloride); Therefore on reclaiming, adopt increased again under the prerequisite of washing, dry, compression pre-treatment reduce the washing water consumption and drop a hint in the absorption of methyl chloride reclaim problem such as the solution recovery is low, contaminate environment, recovery methyl chloride quality are not good again.
Summary of the invention
The objective of the invention is to reclaim and produce the tail gas that contains methyl chloride in the cartap production process; The novel method that provides a kind of cartap hydrolysis tail gas clean-up, the degree of depth to reclaim; And whole recovery technology is environmental protection; Can realize cleaner production, thoroughly solve of the influence of cartap suitability for industrialized production discharging tail gas environment.
The object of the invention can reach through following measure:
A kind of technology that reclaims the methyl chloride that produces in the cartap production process comprises the steps:
1. collect the tail gas that contains methyl chloride that discharges in the cartap production process;
2. adopt the pressurized with fluid and/or the refrigerative separation method that will contain methyl chloride to handle collected tail gas, make wherein methyl alcohol and ethylene dichloride partial liquefaction, obtain methyl chloride through washing, alkali cleaning and dehydration compression again;
3. utilize adsorption medium to reclaim methyl chloride aeriferous dropping a hint after the compression.
The weight content of the methyl chloride that is wherein reclaimed is 20～99.99%, is preferably 99～99.99%.
Wherein to adopt sulphur cyanogen thing, methyl alcohol and hydrogenchloride be that the alcoholysis method of raw material is produced to cartap, and its discharging tail gas is formed and is generally:
| Methyl chloride | Air | Methyl alcohol | Ethylene dichloride | Water | Hydrogenchloride | Other |
| 15-90 | 8-20 | 2-15 | 3-8 | 5-10 | 1-10 | 1-5 |
Methyl alcohol wherein, ethylene dichloride are in saturated or hypersaturated state; The boiling point of normal pressure methanol and ethylene dichloride and emergent pressure are far above methyl chloride; Therefore adopt compression and/or refrigerative method with the methyl alcohol in the gas phase, the most of condensation of ethylene dichloride, thereby can reduce the absorption load of subsequent handling significantly.Methyl chloride saturated vapor pressure at normal temperatures is 506.63Mpa (absolute pressure); Therefore can tail gas be compressed to 0.3-0.8Mpa (absolute pressure); For guaranteeing that methyl alcohol separates with the most economical of methyl chloride, preferred pressure is 0.35-0.45Mpa (absolute pressure), and the separation that is liquefied of methyl alcohol and ethylene dichloride more than 80% will be arranged this moment; This condensation mainly contains methyl alcohol, ethylene dichloride, through simple process can return cyaniding in the cartap production, hydrolyzing process recycles.Partial liquefaction is convection cell pressurization or cooling separately; But consider the cost problem; Also can use pressurization and cooling simultaneously; The state that is about to contain the gas of methyl chloride is adjusted into: pressure be absolute pressure (being absolute pressure) 0.2～0.8Mpa (preferred pressure 0.35～0.45MPa), temperature-35～50 ℃, with 10～99% liquefaction of wherein easy liquefied material methyl alcohol, ethylene dichloride after gas-liquid separation remove.
Can remove the not methyl alcohol of liquefaction through washing, obtain washing gas.Can improve the thick concentration of collecting of methyl alcohol through the method for circulation washing.Because most methyl alcohol, ethylene dichloride separated (being pre-treatment); Can significantly reduce the consumption of washing water; Content for methyl alcohol in rate of mass transfer and the raising washing water adopts the circulation absorption technique, and single tower is adopted according to tolerance in the absorption tower; Perhaps multitower serial or parallel connection, working pressure is 0.15-0.25Mpa (absolute pressure).Contain the methyl alcohol that weight concentration is 10-30% in the washing water, add a certain amount of fresh methanol and can return the hydrolyzing process use.
Still contain carbonic acid gas, hydrogenchloride or vaporific hydrochloric acid in the gas after washing; Can adopt alkali cleaning to remove; The alkali that adopts is generally oxyhydroxide or the carbonate that contains sodium or element; Be preferably weight concentration and be the aqueous solution of 10～40% sodium hydroxide, Pottasium Hydroxide, yellow soda ash or salt of wormwood, the aqueous sodium hydroxide solution that the best is chosen as weight concentration 25-35% absorbs.
Still contain the water of 80-15000ppm in the gas after above-mentioned processing, still do not meet the requirement of industry standard, the method that can pass through the absorption of solution and/or solid adsorbent reduces water cut.Wherein solution dehydrates can be removed most moisture, and it is 70～99% sulfuric acid that solution can be selected mass concentration for use, and adsorptive pressure is absolute pressure 0.1～0.3MPa.Also can adopt solid-state absorption to carry out deep dehydration behind the solvent dehydration, solid adsorbent can be selected oxide compound or anhydrous metal salt for use, is preferably copper sulfate, calcium sulfate, calcium chloride, lime carbonate, water glass, Vanadium Pentoxide in FLAKES, quicklime or 3A aluminum oxide molecular sieve.Moisture content can drop to below the 15ppm after deep dehydration is handled.
Gas after the dehydration is compressed and can obtain methyl chloride.But must after compression, discharge because contain air in certain amount in the tail gas, otherwise can be in the limits of explosion implode, the recovery that therefore liquefies is affected; Consider that the aerial limits of explosion of methyl chloride is 8.1～17.2% (volumes); Therefore the air content in the gas phase tail gas should just can guaranteed security of system below 82.8%; Be that oxygen content in the gas phase should be below 17.38% (volume); In 15% (volume), be equivalent to per hour discharge 15Nm like oxygen content in the gas phase
3Air and 6Nm
3Methyl chloride, do not reclaim the recovery (about 93%) that has not only influenced environment but also reduced methyl chloride like this part methyl chloride.Utilize the excellent grain active carbon of absorption, desorption performance as adsorption medium (its iodine number>=1000mg/g, adsorptive value (CCL to dropping a hint of above situation compression emptying
4)>=70%.), the organism in the organic exhaust gas is adsorbed concrete technology be: adopt two tower alternating temperature adsorption process, tower absorption, another tower regeneration, its adsorptive pressure is absolute pressure power 0.1～0.25Mpa.The absorption pressure compression system is got back to through water vapour in the absorption back, and water of condensation goes Waste Water Treatment to handle.The absorption recovery reaches about 95%, and the recovery of former absorption pressure compression system is 93%, and this methyl chloride total yield reaches 99.65%.Improve the recovery and solved environmental problem.
Pressurization cooling step of the present invention is removed most of methyl alcohol, ethylene dichloride, thereby reduces the water yield of after scouring, alleviates the processing load of the three wastes on the one hand, avoids on the other hand influencing the recovery because of the methyl chloride that washing water are taken away more.And afterwards a part of methyl chloride is taken away in pressurized air emptying meeting, reclaim the recovery (recovery reaches 99%) that wherein methyl chloride had not only been protected environment but also improved methyl chloride through the adsorption medium degree of depth at present.
Whole recovery technology of the present invention is environmental protection, can realize cleaner production, thoroughly solves the influence of cartap suitability for industrialized production discharging tail gas to environment.This method absorption recovery is high, and the mass content of the methyl chloride that is reclaimed can reach 99～99.99%.
Embodiment
Embodiment 1
Use the exhaust port of a pipe connection cartap hydrolysis system and cause a container and be 2m
3Surge tank in, through spinner-type flowmeter, adopt pre-treatment after common process is handled the weight content with methyl chloride and ethylene dichloride in the gas phase examination spectrum analysis exit gas, in each experimentation from surge tank sampling analysis methyl chloride content wherein.
Be compressed to 0.25MPa (absolute pressure) earlier; Be cooled to 10 ℃ through condenser system; Gas phase is used water washing through packing tower again after gas-liquid separation; The washing water that contain methyl alcohol are added and can be returned other operations behind the methyl alcohol and use, and water washing gas absorbs through 32% aqueous sodium hydroxide solution, 95% vitriol oil again, and system pressure maintains about 0.22MPa (absolute pressure).Gas after the sour processed is carried out deep dehydration through the Calcium Chloride Powder Anhydrous drying again.Gas compression with behind the deep dehydration obtains methyl chloride, discharges from the compression set outlet.Content of methyl chloride and impurity are seen shown in the table 1.
Aeriferous the dropping a hint with pipe connection in two tower alternating temperature adsorption process systems in compression back, tower absorption, another tower regeneration.Contain bottom entering A tower absorption wherein the methyl chloride of the gas of methyl chloride from the A tower; After absorption finishes, carry out along putting step-down from the top of A tower, this gas that is rich in methyl chloride is sent to the recovery methyl chloride; Regenerate along feeding water vapor from A tower top after putting, water vapor condensation discharging from the tower bottom, the water of condensation that contains methyl chloride is delivered to the water treatment system processing; A tower behind the steam regeneration is charged to adsorptive pressure with the tail gas that contains methyl chloride, thereby accomplishes an operation cycle.
Two tower alternating temperatures are adsorbed on and carry out high pressure absorption under the 0.15MPa absolute pressure; Absorption finishes the back along putting step-down, and this gas that is rich in methyl chloride is back to dehumidification system and reclaims.Adsorption tower is round diameter 1700mm, the high 6000mm of being, fills up activated carbon in jar.Be metered into and reclaim gas and analyze methyl chloride drainage rate wherein, the result sees for details shown in the table 2.
Embodiment 2
Operation steps is with implementing 1, and pressurization processing under cooling piezometric compression pressure is absolute pressure 0.35MPa, and cooling temperature is 0 ℃, and alkali cleaning use alkali is 29% aqueous sodium hydroxide solution, and the vitriol oil with 98% absorbs, and wherein washing, alkali cleaning and dewatering pressure are absolute pressure 0.19MPa.Adopt anhydrous cupric sulfate to carry out deep dehydration after the dehydration again.Content of methyl chloride and impurity after the compression are seen shown in the table 1.
The adsorptive pressure of dropping a hint is absolute pressure 0.20MPa, is metered into and reclaims gas and analyze methyl chloride drainage rate wherein, and the result sees for details shown in the table 2.
Embodiment 3
Operation steps is with implementing 1, and pressurization processing under cooling piezometric compression pressure is absolute pressure 0.45MPa, and cooling temperature is-5 ℃, and alkali cleaning use alkali is 35% aqueous sodium hydroxide solution, and the vitriol oil with 95% absorbs, and wherein washing, alkali cleaning and dewatering pressure are absolute pressure 0.25MPa.Adopt Carbon Dioxide calcium to carry out deep dehydration after the dehydration again.Content of methyl chloride and impurity after the compression are seen shown in the table 1.
The adsorptive pressure of dropping a hint is absolute pressure 0.22MPa, is metered into and reclaims gas and analyze methyl chloride drainage rate wherein, and the result sees for details shown in the table 2.
The methyl chloride that obtains after table 1 compression and the content of impurity
Table 2 absorption emptying gas result
Claims (9)
1. a technology that reclaims the methyl chloride that produces in the cartap production process is characterized in that comprising the steps:
1. collect the tail gas that contains methyl chloride that discharges in the cartap production process; Described cartap employing sulphur cyanogen thing, methyl alcohol and hydrogenchloride are that the alcoholysis method of raw material is produced;
2. adopt the pressurized with fluid and/or the refrigerative separation method that will contain methyl chloride to handle collected tail gas, make wherein methyl alcohol and ethylene dichloride partial liquefaction, pass through washing, alkali cleaning and dehydration again, compression obtains methyl chloride;
Absorption through solution and solid adsorbent during dehydration reduces water cut; Described solution is that mass concentration is 70～99% sulfuric acid, and adsorptive pressure is absolute pressure 0.1～0.3MPa; Described solid adsorbent is oxide compound or anhydrous metal salt;
3. utilize adsorption medium to reclaim methyl chloride aeriferous dropping a hint after the compression;
Described adsorption medium is a gac; Adsorptive pressure is absolute pressure power 0.1～0.25Mpa.
2. technology according to claim 1, the weight content of the methyl chloride that it is characterized in that being reclaimed is 20～99.99%.
3. technology according to claim 2, the weight content of the methyl chloride that it is characterized in that being reclaimed is 99～99.99%.
4. technology according to claim 1; The state that will contain the gas of methyl chloride when it is characterized in that partial liquefaction is adjusted into: pressure is that absolute pressure 0.2～0.8MPa, temperature are-35～50 ℃, with 10～99% liquefaction of wherein methyl alcohol and ethylene dichloride after gas-liquid separation remove.
5. technology according to claim 1 is washed the gas behind the partial liquefaction when it is characterized in that washing through single-stage washing or plural serial stage, must wash gas.
6. technology according to claim 5, the pressure that adopts when it is characterized in that washing is absolute pressure 0.15～0.25MPa.
7. technology according to claim 1, the alkali that adopts when it is characterized in that the gas alkali cleaning after the washing is oxyhydroxide or the carbonate that contains sodium element.
8. technology according to claim 7, adopting weight concentration when it is characterized in that alkali cleaning is 10～40% the sodium hydroxide or the aqueous solution of yellow soda ash.
9. technology according to claim 1 is characterized in that described solid adsorbent is copper sulfate, calcium sulfate, calcium chloride, lime carbonate, water glass, Vanadium Pentoxide in FLAKES, quicklime or 3A aluminum oxide molecular sieve.
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| Application Number | Priority Date | Filing Date | Title |
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| CN2008101225149A CN101318877B (en) | 2008-06-23 | 2008-06-23 | Process for recycling chloromethane generated in cartap production process |
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| CN2008101225149A CN101318877B (en) | 2008-06-23 | 2008-06-23 | Process for recycling chloromethane generated in cartap production process |
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| CN102935325B (en) * | 2012-10-24 | 2015-05-20 | 大连理工大学 | Method for reducing chloromethane material consumption during butyl rubber production process |
| CN107803109A (en) * | 2017-09-30 | 2018-03-16 | 安徽华星化工有限公司 | Cartap house exhaust processing method |
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN1199921C (en) * | 2002-07-23 | 2005-05-04 | 浙江新安化工集团股份有限公司 | Technique for cleanly recovering byproduct methyl chloride of glyphosate acid |
| CN101012146A (en) * | 2007-02-12 | 2007-08-08 | 张华� | Method of separating and recovering methyl chloride from methyl chloride mixture gas |
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN1199921C (en) * | 2002-07-23 | 2005-05-04 | 浙江新安化工集团股份有限公司 | Technique for cleanly recovering byproduct methyl chloride of glyphosate acid |
| CN101012146A (en) * | 2007-02-12 | 2007-08-08 | 张华� | Method of separating and recovering methyl chloride from methyl chloride mixture gas |
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Address after: 224631 Shugang Highway No.1, Xiangshui Eco-chemical Park, Yancheng City, Jiangsu Province Co-patentee after: Jiangsu Zhongyi Chemicals Co., Ltd. Patentee after: Jiangsu Tianrong Group Co., Ltd. Co-patentee after: Jiangsu Reher Chemical Co., Ltd. Address before: 213300 No. 147 Pingling East Road, Liyang City, Jiangsu Province Co-patentee before: Jiangsu Zhongyi Chemicals Co., Ltd. Patentee before: Jiangsu Tianrong Group Co., Ltd. Co-patentee before: Jiangsu Reher Chemical Co., Ltd. |
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Granted publication date: 20120613 Termination date: 20190623 |