CN111054203A - Tail gas treatment method and system for DMF (dimethyl formamide) wastewater - Google Patents
Tail gas treatment method and system for DMF (dimethyl formamide) wastewater Download PDFInfo
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- CN111054203A CN111054203A CN201911390714.7A CN201911390714A CN111054203A CN 111054203 A CN111054203 A CN 111054203A CN 201911390714 A CN201911390714 A CN 201911390714A CN 111054203 A CN111054203 A CN 111054203A
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- 238000000034 method Methods 0.000 title claims abstract description 25
- ZMXDDKWLCZADIW-UHFFFAOYSA-N N,N-Dimethylformamide Chemical compound CN(C)C=O ZMXDDKWLCZADIW-UHFFFAOYSA-N 0.000 title abstract description 80
- 239000002351 wastewater Substances 0.000 title abstract description 9
- 238000005406 washing Methods 0.000 claims abstract description 69
- 239000002253 acid Substances 0.000 claims abstract description 55
- 239000007921 spray Substances 0.000 claims abstract description 40
- BDAGIHXWWSANSR-UHFFFAOYSA-N methanoic acid Natural products OC=O BDAGIHXWWSANSR-UHFFFAOYSA-N 0.000 claims abstract description 31
- ROSDSFDQCJNGOL-UHFFFAOYSA-N Dimethylamine Chemical compound CNC ROSDSFDQCJNGOL-UHFFFAOYSA-N 0.000 claims abstract description 29
- 239000003513 alkali Substances 0.000 claims abstract description 26
- 238000012856 packing Methods 0.000 claims abstract description 26
- 235000019253 formic acid Nutrition 0.000 claims abstract description 16
- OSWFIVFLDKOXQC-UHFFFAOYSA-N 4-(3-methoxyphenyl)aniline Chemical compound COC1=CC=CC(C=2C=CC(N)=CC=2)=C1 OSWFIVFLDKOXQC-UHFFFAOYSA-N 0.000 claims abstract description 15
- 239000000945 filler Substances 0.000 claims abstract description 15
- 239000000243 solution Substances 0.000 claims description 45
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 25
- 238000004065 wastewater treatment Methods 0.000 claims description 20
- QAOWNCQODCNURD-UHFFFAOYSA-N Sulfuric acid Chemical compound OS(O)(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-N 0.000 claims description 14
- HLBBKKJFGFRGMU-UHFFFAOYSA-M sodium formate Chemical compound [Na+].[O-]C=O HLBBKKJFGFRGMU-UHFFFAOYSA-M 0.000 claims description 11
- NCIDKUDOSHBPMB-UHFFFAOYSA-N n-methylmethanamine;sulfuric acid Chemical compound CNC.OS(O)(=O)=O NCIDKUDOSHBPMB-UHFFFAOYSA-N 0.000 claims description 10
- 235000019254 sodium formate Nutrition 0.000 claims description 10
- 239000004280 Sodium formate Substances 0.000 claims description 9
- 229920003023 plastic Polymers 0.000 claims description 8
- 239000004033 plastic Substances 0.000 claims description 8
- 238000012544 monitoring process Methods 0.000 claims description 6
- 238000004140 cleaning Methods 0.000 claims description 5
- VEXZGXHMUGYJMC-UHFFFAOYSA-N Hydrochloric acid Chemical compound Cl VEXZGXHMUGYJMC-UHFFFAOYSA-N 0.000 claims description 4
- 238000012806 monitoring device Methods 0.000 claims description 4
- 239000012670 alkaline solution Substances 0.000 claims description 3
- 238000007664 blowing Methods 0.000 claims description 3
- 239000002245 particle Substances 0.000 claims 1
- KKCBUQHMOMHUOY-UHFFFAOYSA-N sodium oxide Chemical compound [O-2].[Na+].[Na+] KKCBUQHMOMHUOY-UHFFFAOYSA-N 0.000 claims 1
- 229910001948 sodium oxide Inorganic materials 0.000 claims 1
- 239000001117 sulphuric acid Substances 0.000 claims 1
- 235000011149 sulphuric acid Nutrition 0.000 claims 1
- 239000002649 leather substitute Substances 0.000 abstract description 11
- 238000004519 manufacturing process Methods 0.000 abstract description 4
- 239000010865 sewage Substances 0.000 abstract description 2
- 239000007789 gas Substances 0.000 description 69
- HEMHJVSKTPXQMS-UHFFFAOYSA-M Sodium hydroxide Chemical group [OH-].[Na+] HEMHJVSKTPXQMS-UHFFFAOYSA-M 0.000 description 18
- 238000006243 chemical reaction Methods 0.000 description 11
- 239000012295 chemical reaction liquid Substances 0.000 description 7
- 238000005516 engineering process Methods 0.000 description 7
- 239000002585 base Substances 0.000 description 6
- 239000000463 material Substances 0.000 description 6
- 238000000746 purification Methods 0.000 description 6
- 230000000694 effects Effects 0.000 description 4
- 239000007788 liquid Substances 0.000 description 4
- 230000009286 beneficial effect Effects 0.000 description 3
- 230000007613 environmental effect Effects 0.000 description 3
- MWUXSHHQAYIFBG-UHFFFAOYSA-N nitrogen oxide Inorganic materials O=[N] MWUXSHHQAYIFBG-UHFFFAOYSA-N 0.000 description 3
- 229920005749 polyurethane resin Polymers 0.000 description 3
- 239000002904 solvent Substances 0.000 description 3
- 238000005507 spraying Methods 0.000 description 3
- 239000000126 substance Substances 0.000 description 3
- 239000002912 waste gas Substances 0.000 description 3
- 239000010963 304 stainless steel Substances 0.000 description 2
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 description 2
- 229910000589 SAE 304 stainless steel Inorganic materials 0.000 description 2
- 230000001174 ascending effect Effects 0.000 description 2
- 238000007084 catalytic combustion reaction Methods 0.000 description 2
- 238000002485 combustion reaction Methods 0.000 description 2
- 239000000470 constituent Substances 0.000 description 2
- 239000000835 fiber Substances 0.000 description 2
- 239000008235 industrial water Substances 0.000 description 2
- 238000002156 mixing Methods 0.000 description 2
- 238000007146 photocatalysis Methods 0.000 description 2
- 230000001699 photocatalysis Effects 0.000 description 2
- 238000005554 pickling Methods 0.000 description 2
- 238000011084 recovery Methods 0.000 description 2
- 238000011160 research Methods 0.000 description 2
- 239000012855 volatile organic compound Substances 0.000 description 2
- 239000002699 waste material Substances 0.000 description 2
- 238000010521 absorption reaction Methods 0.000 description 1
- XKMRRTOUMJRJIA-UHFFFAOYSA-N ammonia nh3 Chemical compound N.N XKMRRTOUMJRJIA-UHFFFAOYSA-N 0.000 description 1
- 239000003054 catalyst Substances 0.000 description 1
- 239000003518 caustics Substances 0.000 description 1
- 239000011248 coating agent Substances 0.000 description 1
- 238000000576 coating method Methods 0.000 description 1
- 230000007797 corrosion Effects 0.000 description 1
- 238000005260 corrosion Methods 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 238000011161 development Methods 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 125000002147 dimethylamino group Chemical group [H]C([H])([H])N(*)C([H])([H])[H] 0.000 description 1
- 239000006185 dispersion Substances 0.000 description 1
- 230000008030 elimination Effects 0.000 description 1
- 238000003379 elimination reaction Methods 0.000 description 1
- 230000003628 erosive effect Effects 0.000 description 1
- 239000004744 fabric Substances 0.000 description 1
- 238000007037 hydroformylation reaction Methods 0.000 description 1
- 230000007774 longterm Effects 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 229910052757 nitrogen Inorganic materials 0.000 description 1
- 239000002574 poison Substances 0.000 description 1
- 231100000614 poison Toxicity 0.000 description 1
- 229920000728 polyester Polymers 0.000 description 1
- 229920002635 polyurethane Polymers 0.000 description 1
- 239000004814 polyurethane Substances 0.000 description 1
- 238000003825 pressing Methods 0.000 description 1
- 239000002994 raw material Substances 0.000 description 1
- 150000003839 salts Chemical class 0.000 description 1
- 239000000779 smoke Substances 0.000 description 1
- 238000002791 soaking Methods 0.000 description 1
- 238000012360 testing method Methods 0.000 description 1
- 238000012795 verification Methods 0.000 description 1
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D53/00—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols
- B01D53/34—Chemical or biological purification of waste gases
- B01D53/74—General processes for purification of waste gases; Apparatus or devices specially adapted therefor
- B01D53/77—Liquid phase processes
- B01D53/78—Liquid phase processes with gas-liquid contact
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D53/00—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols
- B01D53/34—Chemical or biological purification of waste gases
- B01D53/46—Removing components of defined structure
- B01D53/54—Nitrogen compounds
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D53/00—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols
- B01D53/34—Chemical or biological purification of waste gases
- B01D53/46—Removing components of defined structure
- B01D53/72—Organic compounds not provided for in groups B01D53/48 - B01D53/70, e.g. hydrocarbons
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D2251/00—Reactants
- B01D2251/30—Alkali metal compounds
- B01D2251/304—Alkali metal compounds of sodium
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D2251/00—Reactants
- B01D2251/50—Inorganic acids
- B01D2251/506—Sulfuric acid
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D2251/00—Reactants
- B01D2251/60—Inorganic bases or salts
- B01D2251/604—Hydroxides
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- Environmental & Geological Engineering (AREA)
- Health & Medical Sciences (AREA)
- Biomedical Technology (AREA)
- Analytical Chemistry (AREA)
- General Chemical & Material Sciences (AREA)
- Oil, Petroleum & Natural Gas (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Treating Waste Gases (AREA)
- Gas Separation By Absorption (AREA)
Abstract
The invention provides a tail gas treatment method and a tail gas treatment system for DMF (dimethyl formamide) wastewater, belonging to the technical field of industrial sewage treatment. Firstly, removing dimethylamine from the generated tail gas by an acid washing tower, and removing formic acid by an alkali washing tower; the acid washing tower comprises a multi-stage packing spray tower, tail gas enters from the bottom of the acid washing tower and is removed by contacting with packing and an acid solution sprayed from top to bottom; the alkaline tower comprises a multi-stage tower plate spray tower, tail gas passing through the acid washing tower enters from the bottom of the alkaline tower and is removed by contacting with a filler and a strong alkali solution sprayed from top to bottom. The invention effectively treats the tail gas (dimethylamine and formic acid) with malodor generated by the treatment process system of the synthetic leather DMF-containing wastewater by utilizing lower cost, and improves the production area and the surrounding air environment.
Description
Technical Field
The invention belongs to the technical field of environmental protection leather-making industrial sewage, relates to DMF-containing wastewater treatment, and particularly relates to a comprehensive treatment technology for tail gas of DMF-containing wastewater.
Background
The wet process polyurethane synthetic leather is produced through adding DMF solvent, other stuffing and assistant into wet polyurethane resin to produce mixed liquid, vacuum defoaming, soaking or coating onto base cloth, adding water with affinity to DMF but not with polyurethane resin, replacing DMF with water to solidify polyurethane resin gradually to form porous film, and dry adhering or surface finishing to form the finished product. Therefore, in the production process of the dry/wet synthetic leather, dimethylformamide (also called DMF, hereinafter referred to as DMF) is needed to be used as a solvent, but the DMF does not participate in the chemical reaction in the production process of the synthetic leather, and is finally dissolved in water and discharged out of a production system. DMF as a solvent can be recycled, so that the economic value of DMF is improved, and COD, ammonia nitrogen and total nitrogen content in the discharged water can be effectively reduced.
DMF can be decomposed in water to generate dimethylamine and formic acid in an accelerated manner under the high-temperature and acid-base environment, and the conventional DMF recovery basically adopts a rectification recovery process, so that DMF can be decomposed to generate a large amount of malodorous dimethylamine and formic acid in the whole process, and the influence on the air environment is large. With the stricter environmental protection policy, the treatment of the tail gas of the three wastes in the DMF-containing wastewater treatment process of the synthetic leather needs to be converted and upgraded, especially in the aspect of tail gas treatment, otherwise, the dry/wet process leather-making industry faces the situation of elimination.
At present, three common synthetic leather tail gas treatment schemes are provided, one scheme is that industrial water is utilized to spray tail gas, dimethylamine in the tail gas is absorbed and dissolved in water, and the absorption efficiency is less than 50%; one method adopts a low-temperature plasma photocatalysis technology, the removal rate of dimethylamine is close to 80%, formic acid cannot be removed, and the odor is still serious; one is to adopt a catalytic combustion scheme, nitrogen oxides in the tail gas after combustion exceed the standard, a catalyst in the tail gas is easy to poison and lose efficacy, the cost is high, odor still exists due to insufficient combustion, and the catalytic combustion scheme is not beneficial to large-scale industrial application. The technology is applied to the industry of treating waste water containing DMF in synthetic leather, but at present, no synthetic leather enterprise can recover and rectify tail gas from DMF waste water to reach the standard, and odor indexes (dimensionless) can not meet the latest national standard (GB 14554-93).
Disclosure of Invention
Aiming at the defects or shortcomings in the prior art, the invention aims to provide a comprehensive treatment method for tail gas generated in a DMF (dimethyl formamide) wastewater treatment process, and solves the problems that the treatment removal rate of the tail gas is not high and formic acid and odor cannot be effectively removed at present.
Therefore, the invention adopts the following technical scheme:
a treatment system for tail gas generated in DMF wastewater treatment is characterized in that the generated tail gas is firstly subjected to dimethylamine removal by an acid washing tower and then subjected to formic acid removal by an alkali washing tower;
the acid washing tower comprises a multi-stage packing spray tower, tail gas enters from the bottom of the acid washing tower and is removed by contacting with packing and an acid solution sprayed from top to bottom;
the alkaline tower comprises a multi-stage tower plate spray tower, tail gas passing through the acid washing tower enters from the bottom of the alkaline tower and is removed by contacting with a filler and a strong alkali solution sprayed from top to bottom.
Preferably, the pH of the acid solution is from 4 to 6.
More preferably, the acid solution comprises a dilute sulfuric acid solution or a dilute hydrochloric acid solution.
Further, the dimethylamine sulfate solution generated in the acid washing tower is recycled after being concentrated.
Preferably, the pH of the strong alkaline solution is from 9 to 11.
Further, the sodium formate solution generated in the alkaline tower is concentrated and then recycled.
More preferably, the packing in the acid or base wash tower comprises plastic particulate packing or plate corrugated packing.
Further, a purified gas monitoring device is arranged at a purified gas outlet of the alkaline tower and used for monitoring the quality of purified gas at the purified gas outlet; the treatment system for tail gas generated in the DMF wastewater treatment also comprises a circulating water system, wherein a water inlet of the circulating water system is arranged in the middle of the acid washing tower or the alkali washing tower, and a water outlet of the circulating water system is arranged at the bottom of the acid washing tower or the alkali washing tower and is used for starting the circulating water system when a purified gas quality monitoring result does not reach a standard, or the tail gas treatment capacity is increased, or the concentration crystallizer is blocked.
Furthermore, the multistage packing spray tower or the multistage tower plate spray tower comprises a plurality of groups of spray pipes, each group of spray pipes is arranged in a cross shape, and a plurality of nozzles are arranged along the spray pipes; the spray nozzles on the adjacent two groups of spray pipes are arranged with different densities: one group of the spray pipes increases the nozzle spacing towards the end of the spray pipes far away from the center of the cross, and the other group increases the nozzle spacing towards the center of the cross along the end of the spray pipes far away from the center of the cross.
Furthermore, a flow guide pipe is communicated with the air inlet of the alkaline tower, the flow guide pipe is provided with an outlet arc-shaped bent end far away from the air inlet of the alkaline tower, and the outlet arc-shaped bent end faces the axis of the alkaline tower and inclines upwards; and a blowing device is arranged at the bottom of the alkaline washing tower just under the arc-shaped bent end of the outlet.
The invention has the following beneficial effects:
at present, tail gas generated by DMF-containing wastewater treatment of synthetic leather is an industrial problem, and no effective treatment scheme exists at present through long-term research of colleges and universities, scientific research institutions and the like, so that the industrial problem is solved by the invention of the technology. Compared with the original tail gas treatment technology, the method reduces the operation cost.
The invention provides a solution of an integrated system for tail gas acid washing and alkali washing, which comprises the following steps: the engineering practice repeated test verifies that the acid solution is a dilute sulfuric acid solution with the PH value of 4-6; the alkali liquor is a sodium hydroxide solution with pH of 9-11, so that the odor index and the VOCs concentration of the tail gas are effectively reduced, the plant area and the surrounding air environment are improved, and the environmental protection benefit is huge.
Meanwhile, the specially designed spray system and the flow guide system of the alkaline washing tower are beneficial to fully mixing gas and liquid, and further enhance the effect of acid washing or alkaline washing.
And moreover, the salts generated by the reaction are concentrated to be used as raw materials in the chemical industry, so that the method can be widely applied to the chemical industry, changes waste into valuable, realizes resource utilization and generates economic value.
Drawings
FIG. 1 is a schematic flow diagram of the system of the present invention.
In the figure, 1, a kettle residue workshop; 2. a circulating fan; 3. an acid liquor circulating pump; 4. an acid washing tower; 5. an alkali liquor circulating pump; 6. an alkaline washing tower; 7. a tail gas discharge port; 8. system tail gas; 9. concentrating sodium formate; 10. dimethylamine sulfate was concentrated.
Detailed Description
The tail gas removing method is a method discovered by the inventor accidentally after trying all schemes in the industry at present, such as an industrial water spraying technology, a photocatalysis technology and the like, and although the technical scheme is common, the industrial problem is solved skillfully.
The plate corrugated filler is developed on the basis of soft filler and semi-soft filler, and has the structure that a plastic wafer is changed into a double-ring large plastic ring by pressing and buckling, and hydroformylation fibers or polyester yarns are pressed on the ring of the ring, so that fiber bundles are uniformly distributed; the inner ring is a snowflake-shaped plastic branch, which can be used for film hanging and can effectively cut bubbles, so that organic matters in water can be efficiently treated.
Example 1:
as shown in figure 1, the invention provides a comprehensive treatment system for tail gas generated in a DMF (dimethyl formamide) wastewater treatment process, which is characterized in that tail gas generated by a DMF-containing synthetic leather wastewater treatment process system is collected, mixed and sequentially enters a tail gas acid washing tower and an alkali washing tower, dimethylamine and formic acid in the tail gas are respectively fixed in the forms of dimethylamine sulfate and sodium formate, the dimethylamine sulfate and the sodium formate are concentrated and then are recycled, and the washed qualified tail gas is discharged into the atmosphere. The method specifically comprises the following scheme:
a treatment system for tail gas generated in DMF wastewater treatment is characterized in that the generated tail gas is firstly subjected to dimethylamine removal by an acid washing tower and then subjected to formic acid removal by an alkali washing tower;
the acid washing tower comprises a multi-stage packing spray tower, tail gas enters from the bottom of the acid washing tower and is removed by contacting with packing and an acid solution sprayed from top to bottom;
the alkaline tower comprises a multi-stage tower plate spray tower, tail gas passing through the acid washing tower enters from the bottom of the alkaline tower and is removed by contacting with a filler and a strong alkali solution sprayed from top to bottom.
Preferably, the pH of the acid solution is from 4 to 6.
More preferably, the acid solution comprises a dilute sulfuric acid solution or a dilute hydrochloric acid solution.
Further, the dimethylamine sulfate solution generated in the acid washing tower is recycled after being concentrated.
Preferably, the pH of the strong alkaline solution is from 9 to 11.
Further, the sodium formate solution generated in the alkaline tower is concentrated and then recycled.
More preferably, the packing in the acid or base wash tower comprises plastic particulate packing or plate corrugated packing.
The system comprises a washing tower, an alkali washing tower, a purification gas outlet, a circulating water system, a circulating gas monitoring device and a circulating water system, wherein the washing tower is used for washing the waste water in the DMF process, the purification gas outlet of the alkali washing tower is provided with the purification gas monitoring device and is used for monitoring the quality of the purification gas at the purification gas outlet, the circulating water system is arranged in the middle of the washing tower or the alkali washing tower, and the water outlet of the circulating water system is arranged at the bottom of the washing tower or the alkali washing tower and is used for starting the circulating water system when the quality monitoring result of the purification gas does not reach the standard, or the treatment capacity of the tail gas is increased, or the concentration crystallizer is blocked.
Furthermore, the multistage packing spray tower or the multistage tower plate spray tower comprises a plurality of groups of spray pipes, each group of spray pipes is arranged in a cross shape, and a plurality of nozzles are arranged along the spray pipes; the spray nozzles on the adjacent two groups of spray pipes are arranged with different densities: one group of the spray pipes increases the nozzle spacing towards the end of the spray pipes far away from the center of the cross, and the other group increases the nozzle spacing towards the center of the cross along the end of the spray pipes far away from the center of the cross. On the one hand, the spraying liquid is not wasted, on the basis, the spraying liquid is fully contacted with the filler and the treated waste gas, and the quality of the purified gas at the outlet is guaranteed to reach the standard.
8. Furthermore, a flow guide pipe is communicated with the air inlet of the alkaline tower, the flow guide pipe is provided with an outlet arc-shaped bent end far away from the air inlet of the alkaline tower, and the outlet arc-shaped bent end faces the axis of the alkaline tower and inclines upwards; and a blowing device is arranged at the bottom of the alkaline washing tower just under the arc-shaped bent end of the outlet. On the one hand, the gas that contains the acid constituent can be introduced into the caustic wash tower middle part through the honeycomb duct, avoids the gas that contains the acid constituent to the erosion and corrosion of tower wall, and on the other hand, the blast apparatus via the middle part is even with pending tail gas at the very first time dispersion to ascending and packing and handling waste gas fully contact in the tower in ascending direction, guarantee that export purified gas quality is up to standard.
The system of the invention specifically comprises the following steps:
the first step is as follows: and mixing odor (the main component is formic acid odor) of the kettle residue discharge workshop, the rectifying tower and waste gas (the main component is dimethylamine and formic acid) collected by non-condensable gas of each rectifying tower reboiler by using a circulating fan.
The second step is that: the mixed odor (dimethylamine and formic acid) enters a tail gas acid washing tower, the tail gas acid washing tower is composed of three layers of tower plates and part of packing (if a reaction tower made of PP materials is adopted, the packing is made of plastic materials, if a tower made of 304 stainless steel materials is adopted, the packing can be corrugated plate regular packing with Y350 holes, the main effect is that the contact area of the reaction tower and the solution is enlarged, the reaction is more complete), the reaction liquid is dilute sulfuric acid solution or dilute hydrochloric acid solution, and the PH value is kept between 4 and 6. Mixed tail gas enters from the middle lower part of the pickling tower, reaction liquid is respectively sprayed to the three layers of tower plates by using a circulating pump, the tail gas and the reaction liquid are fully reacted on the tower plates and the filler, the generated dimethylamine sulfate solution enters the bottom of the pickling tower, the saturated dimethylamine sulfate solution is concentrated and then is recycled, and dimethylamine odor is basically and completely reacted in the process.
The reaction mechanism of the process is that dimethylamine has weak alkalinity and can react with strong acid sulfuric acid to generate dimethylamine sulfate, and the reaction formula is as follows:
2C2H3NH+H2SO4→(C2H3NH)2·H2SO4
the third step: the tail gas after acid washing enters an alkaline washing tower, the tail gas alkaline washing tower is composed of three layers of tower plates and packing (if a reaction tower made of PP materials is adopted, the packing is made of plastic materials, if a tower made of 304 stainless steel materials is adopted, the packing can be corrugated plate regular packing with Y350 holes, the main function is to increase the contact area of the tail gas and the solution for reaction and enable the tail gas to react more fully), the reaction liquid is sodium hydroxide solution (the reaction liquid is strong base solution, and the sodium hydroxide is only one of the most ideal strong base solutions), and the pH value is kept at 9-11. Tail gas enters from the bottom of the alkaline washing tower, reaction liquid is respectively sprayed to three layers of tower plates by using a circulating pump, the tail gas and the reaction liquid fully react on the tower plates and the filler, the produced sodium formate solution enters the bottom of the alkaline washing tower, the saturated sodium formate solution is concentrated and then recycled, and the tail gas after alkaline washing can meet the latest standard (GB 14554-93).
The reaction mechanism of the process is that formic acid has strong basicity and can react with strong basicity sodium hydroxide to generate sodium formate, and the reaction formula is as follows:
HCOOH+NaOH→HCOONa+H2O
the fourth step: dimethylamine sulfate and sodium formate are concentrated and sold to corresponding chemical enterprises, so that resource utilization is realized, and economic benefit is improved.
Effect verification:
according to the system, when the air volume of the treated odor is 8000m3/h, the heights of the tail gas acid cleaning tower and the tail gas alkali cleaning tower are 6000mm, the diameter of the tower is 1500mm, three layers of fillers are arranged, and the total area of the fillers in one tower is 235 square meters. When the amount of 98% concentrated sulfuric acid solution consumed by the acid washing tower is 20L/h, and the amount of 32% sodium hydroxide solution consumed by the alkaline washing tower is 2L/h, tail gas after acid washing and alkaline washing is monitored by an authority, and VOCs are 6.63mg/m3(the latest national norm is 200mg/m3Inner, GB21902-2008), odor index (dimensionless) 309 (latest national standard GB14554-93 stipulates that the height of the smoke exhaust pipe is within 20 meters, and the odor index is not more than 2000. ) The exhaust gas discharge port has no stink any more, and the whole plant area and the surrounding air environment are greatly improved. The obtained effect belongs to the best industry at present.
The invention is applied to the centralized rectification treatment project of synthetic leather containing DMF high-concentration wastewater from Zhejiang Shanxi drum energy development Limited company, and is monitored by a third party authority, and the data is as follows:
as described above, the present invention can be preferably realized. The above-mentioned embodiments are only examples of the present invention, and are not intended to limit the scope of the present invention, i.e., all equivalent variations and modifications of the present invention are covered by the scope of the claims of the present invention.
Claims (10)
1. A treatment method for tail gas generated in DMF wastewater treatment is characterized in that the generated tail gas is firstly subjected to acid cleaning to remove dimethylamine and then subjected to alkali cleaning to remove formic acid.
2. The method for treating tail gas generated in DMF wastewater treatment according to claim 1, wherein the pH value of the acid solution used for acid washing is 4-6; the pH value of the strong alkali solution used for alkali washing is 9-11.
3. The method for treating tail gas generated in DMF wastewater treatment according to claim 1 or 2, wherein the acid solution used for acid washing comprises dilute sulphuric acid solution or dilute hydrochloric acid solution; the strong alkaline solution used for the alkaline cleaning includes a strong sodium oxide solution.
4. The treatment system for tail gas generated in the DMF wastewater treatment of claim 1, which is characterized in that the generated tail gas is firstly subjected to an acid washing tower to remove dimethylamine and then is subjected to an alkali washing tower to remove formic acid;
the acid washing tower comprises a multi-stage packing spray tower, tail gas enters from the bottom of the acid washing tower and is removed by contacting with packing and an acid solution sprayed from top to bottom;
the alkaline tower comprises a multi-stage tower plate spray tower, tail gas passing through the acid washing tower enters from the bottom of the alkaline tower and is removed by contacting with a filler and a strong alkali solution sprayed from top to bottom.
5. The system for treating tail gas generated in DMF wastewater treatment according to claim 4, wherein the ratio of the tail gas treatment capacity per hour to the consumed acid solution with the volume concentration of 98% is 400m3-500m3/: 1L; the ratio of the tail gas treatment amount per hour to the consumed strong alkali solution with the volume concentration of 32-35% is 4000m3-4500m3/：1L。
6. The treatment system for tail gas generated in DMF wastewater treatment according to claim 4, wherein dimethylamine sulfate solution generated in the acid washing tower is recycled after passing through the concentration crystallizer; and the sodium formate solution generated in the alkaline tower is recycled after passing through a concentration crystallizer.
7. The system for treating tail gas generated in DMF wastewater treatment as claimed in claim 4, wherein the filler in the acid washing tower or the alkali washing tower comprises plastic particle filler or plate corrugated filler.
8. The system for treating tail gas generated in DMF wastewater treatment as defined in claim 6, wherein a purified gas monitoring device is arranged at the purified gas outlet of the alkaline tower for monitoring the quality of the purified gas at the purified gas outlet;
the treatment system for tail gas generated in the DMF wastewater treatment also comprises a circulating water system, wherein a water inlet of the circulating water system is arranged in the middle of the acid washing tower or the alkali washing tower, and a water outlet of the circulating water system is arranged at the bottom of the acid washing tower or the alkali washing tower and is used for starting the circulating water system when a purified gas quality monitoring result does not reach a standard, or the tail gas treatment capacity is increased, or the concentration crystallizer is blocked.
9. The treatment system for tail gas generated in DMF wastewater treatment according to claim 4, wherein the multistage packing spray tower or multistage column plate spray tower comprises a plurality of groups of spray pipes, each group of spray pipes is arranged in a crisscross manner, and a plurality of nozzles are arranged along the spray pipes; the spray nozzles on the adjacent two groups of spray pipes are arranged with different densities: one group of the spray pipes increases the nozzle spacing towards the end of the spray pipes far away from the center of the cross, and the other group increases the nozzle spacing towards the center of the cross along the end of the spray pipes far away from the center of the cross.
10. The system for treating tail gas generated in the DMF wastewater treatment according to claim 4, wherein a flow guide pipe is communicated with the air inlet of the alkaline tower, and the flow guide pipe is provided with an outlet arc-shaped bent end far away from the air inlet of the alkaline tower, and the outlet arc-shaped bent end faces to the axis of the alkaline tower and inclines upwards; and a blowing device is arranged at the bottom of the alkaline washing tower just under the arc-shaped bent end of the outlet.
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