CN111054203B - Tail gas treatment method and system for DMF wastewater - Google Patents
Tail gas treatment method and system for DMF wastewater Download PDFInfo
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- CN111054203B CN111054203B CN201911390714.7A CN201911390714A CN111054203B CN 111054203 B CN111054203 B CN 111054203B CN 201911390714 A CN201911390714 A CN 201911390714A CN 111054203 B CN111054203 B CN 111054203B
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- alkaline washing
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- 238000000034 method Methods 0.000 title abstract description 18
- 239000002351 wastewater Substances 0.000 title abstract description 6
- 238000005406 washing Methods 0.000 claims abstract description 59
- 239000007921 spray Substances 0.000 claims abstract description 41
- 238000005554 pickling Methods 0.000 claims abstract description 30
- 239000002253 acid Substances 0.000 claims abstract description 29
- 239000000945 filler Substances 0.000 claims abstract description 29
- BDAGIHXWWSANSR-UHFFFAOYSA-N methanoic acid Natural products OC=O BDAGIHXWWSANSR-UHFFFAOYSA-N 0.000 claims abstract description 29
- ROSDSFDQCJNGOL-UHFFFAOYSA-N Dimethylamine Chemical compound CNC ROSDSFDQCJNGOL-UHFFFAOYSA-N 0.000 claims abstract description 27
- 239000003513 alkali Substances 0.000 claims abstract description 18
- 238000004065 wastewater treatment Methods 0.000 claims abstract description 18
- 235000019253 formic acid Nutrition 0.000 claims abstract description 15
- 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 14
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 25
- QAOWNCQODCNURD-UHFFFAOYSA-N Sulfuric acid Chemical compound OS(O)(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-N 0.000 claims description 13
- 238000012856 packing Methods 0.000 claims description 12
- HLBBKKJFGFRGMU-UHFFFAOYSA-M sodium formate Chemical compound [Na+].[O-]C=O HLBBKKJFGFRGMU-UHFFFAOYSA-M 0.000 claims description 10
- NCIDKUDOSHBPMB-UHFFFAOYSA-N n-methylmethanamine;sulfuric acid Chemical compound CNC.OS(O)(=O)=O NCIDKUDOSHBPMB-UHFFFAOYSA-N 0.000 claims description 9
- 235000019254 sodium formate Nutrition 0.000 claims description 9
- 239000004280 Sodium formate Substances 0.000 claims description 8
- 239000004033 plastic Substances 0.000 claims description 8
- 229920003023 plastic Polymers 0.000 claims description 8
- 238000012544 monitoring process Methods 0.000 claims description 7
- 239000002585 base Substances 0.000 claims description 5
- 238000007664 blowing Methods 0.000 claims description 4
- 238000005452 bending Methods 0.000 claims description 3
- 238000012806 monitoring device Methods 0.000 claims description 3
- 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
- 239000002649 leather substitute Substances 0.000 abstract description 11
- 230000008569 process Effects 0.000 abstract description 11
- 238000004519 manufacturing process Methods 0.000 abstract description 4
- 239000010865 sewage Substances 0.000 abstract description 2
- ZMXDDKWLCZADIW-UHFFFAOYSA-N N,N-Dimethylformamide Chemical compound CN(C)C=O ZMXDDKWLCZADIW-UHFFFAOYSA-N 0.000 description 79
- 239000007789 gas Substances 0.000 description 66
- 239000000243 solution Substances 0.000 description 35
- HEMHJVSKTPXQMS-UHFFFAOYSA-M Sodium hydroxide Chemical compound [OH-].[Na+] HEMHJVSKTPXQMS-UHFFFAOYSA-M 0.000 description 18
- 238000006243 chemical reaction Methods 0.000 description 13
- 238000005516 engineering process Methods 0.000 description 6
- 239000012295 chemical reaction liquid Substances 0.000 description 4
- 239000007788 liquid Substances 0.000 description 4
- 239000002904 solvent Substances 0.000 description 4
- VEXZGXHMUGYJMC-UHFFFAOYSA-N Hydrochloric acid Chemical compound Cl VEXZGXHMUGYJMC-UHFFFAOYSA-N 0.000 description 3
- 239000004743 Polypropylene Substances 0.000 description 3
- 230000000694 effects Effects 0.000 description 3
- 230000007613 environmental effect Effects 0.000 description 3
- 239000000463 material Substances 0.000 description 3
- 230000007246 mechanism Effects 0.000 description 3
- MWUXSHHQAYIFBG-UHFFFAOYSA-N nitrogen oxide Inorganic materials O=[N] MWUXSHHQAYIFBG-UHFFFAOYSA-N 0.000 description 3
- 238000011084 recovery Methods 0.000 description 3
- 238000004064 recycling 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
- 230000009286 beneficial effect Effects 0.000 description 2
- 230000008901 benefit Effects 0.000 description 2
- 238000002485 combustion reaction Methods 0.000 description 2
- 238000000354 decomposition reaction Methods 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
- 229920005749 polyurethane resin Polymers 0.000 description 2
- 238000005507 spraying Methods 0.000 description 2
- 239000012855 volatile organic compound Substances 0.000 description 2
- 239000002699 waste material Substances 0.000 description 2
- -1 Polypropylene Polymers 0.000 description 1
- 238000010521 absorption reaction Methods 0.000 description 1
- 239000012670 alkaline solution Substances 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
- 238000007084 catalytic combustion reaction Methods 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
- 238000013461 design Methods 0.000 description 1
- 238000011161 development Methods 0.000 description 1
- 125000002147 dimethylamino group Chemical group [H]C([H])([H])N(*)C([H])([H])[H] 0.000 description 1
- 238000007599 discharging Methods 0.000 description 1
- 238000002474 experimental method Methods 0.000 description 1
- 239000004744 fabric Substances 0.000 description 1
- 125000002485 formyl group Chemical class [H]C(*)=O 0.000 description 1
- 239000010985 leather Substances 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
- 229920001155 polypropylene Polymers 0.000 description 1
- 229920002635 polyurethane Polymers 0.000 description 1
- 239000004814 polyurethane Substances 0.000 description 1
- 239000002994 raw material Substances 0.000 description 1
- 238000011160 research Methods 0.000 description 1
- 150000003839 salts Chemical class 0.000 description 1
- 238000009991 scouring Methods 0.000 description 1
- 238000002791 soaking Methods 0.000 description 1
- 238000012795 verification Methods 0.000 description 1
Classifications
-
- 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
Abstract
The invention provides a tail gas treatment method and a tail gas treatment system for DMF wastewater, and belongs to the technical field of industrial sewage treatment. Firstly, 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 pickling tower comprises a multi-stage filler spray tower, tail gas enters from the bottom of the pickling tower and is removed by contacting with the filler and acid solution sprayed from top to bottom; the alkaline washing tower comprises a multi-stage tower plate spray tower, tail gas from the acid washing tower enters from the bottom of the alkaline washing tower, and is contacted with the filler and strong alkali solution sprayed from top to bottom to be removed. The invention effectively treats the malodorous tail gas (dimethylamine and formic acid) generated by the DMF wastewater treatment process system of the synthetic leather by using 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 tanning industrial sewage, relates to DMF (dimethyl formamide) -containing wastewater treatment, and in particular relates to a comprehensive tail gas treatment technology of DMF-containing wastewater.
Background
The wet process polyurethane synthetic leather is produced through the steps of adding DMF solvent, other stuffing and assistant into wet process polyurethane resin to prepare mixed liquid, defoaming in vacuum machine, soaking or coating onto base cloth, and setting in water with affinity to the solvent (DMF) and no affinity to the polyurethane resin. It can be seen that Dimethylformamide (DMF) is required to be used as a solvent (also called DMF hereinafter, DMF) in the dry/wet synthetic leather production process, but DMF does not participate in chemical reaction in the synthetic leather production process, and finally is dissolved in water and discharged out of the production system. DMF can be recycled as a solvent, so that on one hand, the economic value of the DMF is improved, and on the other hand, the COD, ammonia nitrogen and total nitrogen content in the discharged water can be effectively reduced.
Since DMF is decomposed when meeting water, dimethylamine and formic acid can be produced by accelerating the decomposition under the high temperature and acid-base environment, the prior DMF recovery basically adopts a rectification recovery process, and a large amount of dimethylamine and formic acid with malodor can be produced by the DMF decomposition in the whole process, so that the influence on the air environment is great. With the increasing stricter environmental protection policy, the treatment of the three wastes tail gas of the DMF wastewater treatment process of the synthetic leather must be transformed and upgraded, especially in the aspect of tail gas treatment, otherwise, the dry/wet leather industry faces the obsolete situation.
At present, three common synthetic leather tail gas treatment schemes are adopted, 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 is to adopt a low-temperature plasma photocatalysis technology, the dimethylamine removal rate is close to 80 percent, formic acid can not be removed, and the malodor is still serious; one is to adopt the catalytic combustion scheme, the nitrogen oxides in the tail gas after combustion exceed standard, the catalyst in the tail gas is easy to poison and lose efficacy, the cost is high, the odor still exists due to insufficient combustion, and the large-scale industrialized application is not facilitated. The technology is applied to the DMF wastewater treatment industry of synthetic leather, but until the current time, the DMF wastewater recovery rectification tail gas treatment of the synthetic leather enterprises is up to the standard, and the odor indexes (dimensionless) do not meet the latest national standard (GB 14554-93).
Disclosure of Invention
Aiming at the defects or shortcomings of the prior art, the invention aims to provide a comprehensive treatment method for tail gas generated in the DMF wastewater treatment process, which solves the problems that the prior treatment and removal rate of the tail gas is low and formic acid and odor cannot be effectively removed.
For this purpose, the invention adopts the following technical scheme:
a treatment system for tail gas generated in DMF wastewater treatment comprises the steps of removing dimethylamine from the generated tail gas through an acid washing tower, and removing formic acid through an alkaline washing tower;
the pickling tower comprises a multi-stage filler spray tower, tail gas enters from the bottom of the pickling tower and is removed by contacting with the filler and acid solution sprayed from top to bottom;
the alkaline washing tower comprises a multi-stage tower plate spray tower, tail gas from the acid washing tower enters from the bottom of the alkaline washing tower, and is contacted with the filler and strong alkali solution sprayed from top to bottom to be removed.
Preferably, the pH of the acid solution is 4-6.
More preferably, the acid solution comprises a dilute sulfuric acid solution or a dilute hydrochloric acid solution.
Further, dimethylamine sulfate solution generated in the pickling tower is concentrated and then recycled.
Preferably, the pH of the strong base solution is from 9 to 11.
Further, the sodium formate solution generated in the alkaline washing tower is concentrated and then recycled.
More preferably, the packing in the acid wash column or the alkali wash column comprises plastic particulate packing or plate corrugated packing.
Further, a purified gas monitoring device is arranged at the purified gas outlet of the alkaline washing tower and is used for monitoring the quality of purified gas at the purified gas outlet; the treatment system for tail gas generated in DMF wastewater treatment further comprises a circulating water system, wherein a water inlet of the circulating water system is arranged in the middle of the pickling tower or the alkaline washing tower, and a water outlet of the circulating water system is arranged at the bottom of the pickling tower or the alkaline washing tower and is used for starting the circulating water system when the quality monitoring result of purified gas does not reach the standard, or when the tail gas treatment capacity is increased, or when a concentration crystallizer is blocked.
Further, the multi-stage filler spray tower or the multi-stage tower plate spray tower comprises a plurality of groups of spray pipes, wherein each group of spray pipes are arranged in a crisscross manner, and a plurality of nozzles are arranged along the spray pipes; the spray nozzles on the spray pipes of two adjacent groups are different in density: one group of spray pipes increases in nozzle spacing along the center of the cross toward the end of the spray pipe away from the center of the cross, and the other group increases in nozzle spacing along the end of the spray pipe away from the center of the cross toward the center of the cross.
Further, a guide pipe is communicated with the air inlet of the alkaline washing tower, the guide pipe is provided with an outlet arc-shaped bent end far away from the air inlet of the alkaline washing tower, and the outlet arc-shaped bent end faces the axis of the alkaline washing tower and inclines upwards; and a blowing device is arranged at the bottom of the alkaline washing tower and is opposite to the lower part of the arc-shaped bending end of the outlet.
The invention has the following beneficial effects:
at present, tail gas generated by DMF wastewater treatment of synthetic leather is a difficult problem in industry, and through long-term research of universities and scientific institutions, no effective treatment scheme exists so far, and the technical invention solves the difficult problem in industry. Compared with the original tail gas treatment technology, the operation cost is reduced.
The invention provides a solution of an integrated system for pickling and alkaline washing of tail gas, which comprises the following steps: proved by engineering practical repeated experiments, the acid liquor is dilute sulfuric acid solution with pH of 4-6; the alkaline solution is sodium hydroxide solution with pH of 9-11, so that the odor index and VOCs concentration of tail gas are effectively reduced, the factory and surrounding air environment are improved, and the environmental protection benefit is great.
Meanwhile, the special design of the spraying system and the alkali washing tower diversion system is beneficial to fully mixing gas and liquid, and further enhances the effect of acid washing or alkali washing.
In addition, the salt generated by the reaction can be widely applied to the chemical industry after being concentrated as a raw material in the chemical industry, thereby changing waste into valuable, recycling and producing economic value.
Drawings
Fig. 1 is a schematic flow chart 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. a pickling tower; 5. an alkali liquor circulating pump; 6. an alkaline washing tower; 7. a tail gas discharge port; 8. tail gas of the system; 9. concentrating sodium formate; 10. dimethylamine sulfate concentration.
Detailed Description
The tail gas removing method is a method which is discovered accidentally after the inventor tries all schemes in the current industries such as an industrial water spraying technology, a photocatalysis technology and the like, and the technical scheme is common but skillfully solves the industrial problem.
The plate ripple packing is developed on the basis of soft packing and semi-soft packing, and has the structure that a plastic wafer is pressed and buckled into a double-ring large plastic ring, and aldehyde fiber or polyester yarn is pressed on the ring of the ring, so that fiber bundles are uniformly distributed; the inner ring is a snowflake-shaped plastic branch, so that the film can be hung, air bubbles can be effectively cut, and organic matters in water can be efficiently treated.
Example 1:
as shown in fig. 1, the invention provides a comprehensive treatment system for tail gas generated in a DMF wastewater treatment process, which is characterized in that the tail gas generated in the DMF wastewater treatment process system for synthetic leather is collected and mixed and sequentially enters a tail gas pickling tower and an alkaline washing tower, dimethylamine and formic acid in the tail gas are respectively fixed in the forms of dimethylamine sulfate and sodium formate for concentrating and then recycling, and the washed qualified tail gas is discharged into the atmosphere. The method specifically comprises the following steps:
a treatment system for tail gas generated in DMF wastewater treatment comprises the steps of removing dimethylamine from the generated tail gas through an acid washing tower, and removing formic acid through an alkaline washing tower;
the pickling tower comprises a multi-stage filler spray tower, tail gas enters from the bottom of the pickling tower and is removed by contacting with the filler and acid solution sprayed from top to bottom;
the alkaline washing tower comprises a multi-stage tower plate spray tower, tail gas from the acid washing tower enters from the bottom of the alkaline washing tower, and is contacted with the filler and strong alkali solution sprayed from top to bottom to be removed.
Preferably, the pH of the acid solution is 4-6.
More preferably, the acid solution comprises a dilute sulfuric acid solution or a dilute hydrochloric acid solution.
Further, dimethylamine sulfate solution generated in the pickling tower is concentrated and then recycled.
Preferably, the pH of the strong base solution is from 9 to 11.
Further, the sodium formate solution generated in the alkaline washing tower is concentrated and then recycled.
More preferably, the packing in the acid wash column or the alkali wash column comprises plastic particulate packing or plate corrugated packing.
Further, a purified gas monitoring device is arranged at the purified gas outlet of the alkaline washing tower and is used for monitoring the quality of purified gas at the purified gas outlet; the treatment system for tail gas generated in DMF wastewater treatment further comprises a circulating water system, wherein a water inlet of the circulating water system is arranged in the middle of the pickling tower or the alkaline washing tower, and a water outlet of the circulating water system is arranged at the bottom of the pickling tower or the alkaline washing tower and is used for starting the circulating water system when the quality monitoring result of purified gas does not reach the standard, or when the tail gas treatment capacity is increased, or when a concentration crystallizer is blocked. The circulating water system of the invention has three functions: (1) temporarily starting when the quality monitoring result of the purified gas does not reach the standard; (2) when the tail gas treatment capacity is increased, temporarily starting; (3) when the concentration crystallizer is blocked, the device is opened. The stable operation of the system is ensured, and the quality of the outlet purified gas reaches the standard.
Further, the multi-stage filler spray tower or the multi-stage tower plate spray tower comprises a plurality of groups of spray pipes, wherein each group of spray pipes are arranged in a crisscross manner, and a plurality of nozzles are arranged along the spray pipes; the spray nozzles on the spray pipes of two adjacent groups are different in density: one group of spray pipes increases in nozzle spacing along the center of the cross toward the end of the spray pipe away from the center of the cross, and the other group increases in nozzle spacing along the end of the spray pipe away from the center of the cross toward the center of the cross. On the one hand, the spray liquid is ensured not to be wasted, on the basis, the spray liquid is ensured to be fully contacted with the filler and the treated waste gas, and the quality of the outlet purified gas is ensured to reach the standard.
8. Further, a guide pipe is communicated with the air inlet of the alkaline washing tower, the guide pipe is provided with an outlet arc-shaped bent end far away from the air inlet of the alkaline washing tower, and the outlet arc-shaped bent end faces the axis of the alkaline washing tower and inclines upwards; and a blowing device is arranged at the bottom of the alkaline washing tower and is opposite to the lower part of the arc-shaped bending end of the outlet. On the one hand, the gas containing the acid component can be introduced into the middle part of the alkaline washing tower through the flow guide pipe, so that the scouring corrosion of the gas containing the acid component to the tower wall is avoided, on the other hand, the tail gas to be treated is uniformly dispersed in the first time through the air blowing device in the middle part, and rises in the tower in an upward direction to fully contact with the filler and the treated waste gas, so that the quality of the outlet purified gas is ensured to reach the standard.
The system of the invention specifically comprises the following steps:
the first step: and mixing the odor (the main component is formic acid odor) of the kettle residue discharging workshop, the rectifying towers and waste gas (the main component is dimethylamine and formic acid) collected by non-condensable gases of reboilers of the rectifying towers by using a circulating fan.
And a second step of: the mixed odor (dimethylamine and formic acid) enters a tail gas pickling tower, the tail gas pickling tower is composed of three layers of tower plates and partial filler (if a reaction tower made of PP (Polypropylene) is adopted, the filler is made of plastic, and if a tower made of 304 stainless steel is adopted, the filler can be a Y350-hole corrugated plate structured filler, so that the contact area for the mixed odor and the solution is enlarged, the reaction is more sufficient), the reaction solution is dilute sulfuric acid solution or dilute hydrochloric acid solution, and the pH value is kept between 4 and 6. The mixed tail gas enters from the middle lower part of the pickling tower, the reaction liquid is sprayed to three layers of tower plates respectively by utilizing a circulating pump, the tail gas and the reaction liquid fully react on the tower plates and the filler, the produced dimethylamine sulfate solution enters the bottom of the pickling tower, and the saturated dimethylamine sulfate solution is concentrated and then recycled, so that the dimethylamine odor is basically reacted completely 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:
2C 2 H 3 NH+H 2 SO 4 →(C 2 H 3 NH) 2 ·H 2 SO 4
and a third step of: 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 a filler (if a reaction tower made of PP material is adopted, the filler is made of plastic material, and if a tower made of 304 stainless steel material is adopted, the filler can be made of a Y350-hole corrugated plate structured filler, so that the contact area for reaction with the solution is enlarged, the reaction is more complete, a sodium hydroxide solution (here, the sodium hydroxide is only one of the most ideal alkali solutions) is adopted as the reaction solution, and the PH value is kept at 9-11. The tail gas enters from the bottom of the alkaline washing tower, the reaction liquid is sprayed to three layers of tower plates respectively by utilizing 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 alkalinity and can react with strong alkali sodium hydroxide to generate sodium formate, and the reaction formula is as follows:
HCOOH+NaOH→HCOONa+H 2 O
fourth step: the dimethylamine sulfate and the sodium formate are concentrated and sold to corresponding chemical enterprises, so that the recycling utilization is realized, and the economic benefit is improved.
And (3) effect verification:
the system of the invention has three layers of fillers, namely, the total filler area of one tower is 235 square meters, wherein the odor treatment air quantity is 8000m3/h, the heights of the tail gas pickling tower and the alkaline washing tower are 6000mm, the tower diameter is 1500 mm. The pickling tower consumes 98% concentrated sulfuric acid solution of 20L/h, and the alkaline tower consumes 32% sodium hydroxide solution of 2L/h, and the pickling tower is subjected to pickling and alkaline washingIs monitored by an authority mechanism, and the VOCs is 6.63mg/m 3 (the latest national standard is 200 mg/m) 3 In the above, GB 21902-2008), an odor index (dimensionless) 309 (latest national standard GB14554-93 prescribes that the height of the chimney is within 20 meters, and the odor index is not more than 2000. ) The exhaust emission port no longer has stink, and the whole factory area and the surrounding air environment are greatly improved. The obtained effect is the best in the current industry.
The invention is applied to the concentrated rectification treatment project of DMF-containing high-concentration wastewater of Zhejiang Shaanxi drum energy development limited company synthetic leather, and is monitored by a third-party authority, and the data are as follows:
as described above, the present invention can be preferably realized. The above embodiment is only one embodiment of the present invention, and is not intended to limit the scope of the present invention, i.e., all equivalent changes and modifications made by the present invention are covered by the scope of the claims.
Claims (5)
1. A treatment system for tail gas generated in DMF wastewater treatment is characterized in that the generated tail gas is firstly subjected to an acid washing tower to remove dimethylamine, and then subjected to an alkali washing tower to remove formic acid;
the pH value of the acid solution used for pickling is 4-6; the pH value of the alkali solution used for alkali washing is 9-11; the acid solution used for pickling is dilute sulfuric acid solution; strong alkali solution used for alkali washing is strong sodium oxide solution;
the pickling tower comprises a multi-stage filler spray tower, tail gas enters from the bottom of the pickling tower and is removed by contacting with the filler and acid solution sprayed from top to bottom;
the alkaline washing tower comprises a multi-stage tower plate spray tower, tail gas from the acid washing tower enters from the bottom of the alkaline washing tower, and is contacted with a filler and strong alkali solution sprayed from top to bottom to be removed;
the multi-stage filler spray tower or the multi-stage tower plate spray tower comprises a plurality of groups of spray pipes, wherein each group of spray pipes are arranged in a crisscross manner, and a plurality of nozzles are arranged along the spray pipes; the spray nozzles on the spray pipes of two adjacent groups are different in density: one group of spray pipes far from the cross center are provided with nozzle spacing which is increased along the cross center, and the other group of spray pipes far from the cross center are provided with nozzle spacing which is increased along one end of the spray pipes far from the cross center;
a guide pipe is communicated with the air inlet of the alkaline washing tower, and is provided with an outlet arc-shaped bent end far away from the air inlet of the alkaline washing tower, and the outlet arc-shaped bent end faces the axis of the alkaline washing tower and inclines upwards; and a blowing device is arranged at the bottom of the alkaline washing tower and is opposite to the lower part of the arc-shaped bending end of the outlet.
2. The treatment system for generating tail gas in DMF wastewater treatment as claimed in claim 1, wherein the ratio of the tail gas treatment amount per hour to the 98% acid solution consumed by volume concentration is 400m 3 -500m 3 /: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 4000m 3 -4500m 3 /：1L。
3. The treatment system for tail gas generated in DMF wastewater treatment according to claim 1, wherein dimethylamine sulfate solution generated in the pickling tower is recycled after passing through a concentration crystallizer; the sodium formate solution produced in the alkaline washing tower is recycled after passing through a concentration crystallizer.
4. The abatement system for generating tail gas in DMF waste water treatment of claim 1, wherein the packing in the acid wash tower or the base wash tower comprises plastic particulate packing or board corrugated packing.
5. A treatment system for generating tail gas in DMF waste water treatment as claimed in claim 3, wherein a purified gas monitoring device is provided at the purified gas outlet of the alkaline scrubber for monitoring the purified gas quality of the purified gas outlet;
the treatment system for tail gas generated in DMF wastewater treatment further comprises a circulating water system, wherein a water inlet of the circulating water system is arranged in the middle of the pickling tower or the alkaline washing tower, and a water outlet of the circulating water system is arranged at the bottom of the pickling tower or the alkaline washing tower and is used for starting the circulating water system when the quality monitoring result of purified gas does not reach the standard, or when the tail gas treatment capacity is increased, or when a concentration crystallizer is blocked.
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