Method for treating organic waste gas of methylamine co-production DMF (Dimethyl Formamide) device

Abstract

The invention discloses a method for treating organic waste gas of a methylamine co-production DMF (Dimethyl Formamide) device, which comprises the following steps of: introducing the organic waste gas generated in waste water of the methylamine co-production DMF device into a waste gas collecting header pipe through negative pressure pumping of an induced draft fan, and removing water-soluble organic matters and particulate matters from the organic waste gas through a water washing tower; the waste gas washed by the water washing tower is subjected to acid washing and alkali washing, so that acid-alkali substances in the organic waste gas are subjected to a neutralization reaction, odor in the organic waste gas is removed, and inorganic salt and water are generated; feeding the treated organic waste gas into a demister to remove moisture in the waste gas, and adsorbing organic substances by using activated carbon; feeding the treated waste gas into a deodorization spray tower for atomization, combining atomized liquid with the odorous gas to generate coating, oxidation and decomposition reactions, and finally converting the odorous gas into carbon dioxide, water and inorganic salt; and the treated and up-to-standard waste gas is discharged through a chimney. According to the invention, the exhaust gas can reach the standard and be discharged, and the surrounding environment is obviously improved.

Description

Technical Field

[0001] The patent of this invention relates to the field of fine chemical technology, specifically to a method for treating organic waste gas generated during the wastewater treatment process of a methylamine co-production DMF device. Background Art

[0002] The wastewater generated during the operation of the fine chemical production of methylamine and DMF units will release a large amount of organic waste gas during the treatment process. If not effectively treated, it will have a certain impact on the surrounding environment and air quality.

[0003] In order to reduce the impact on the environment, optimize the air quality around the production unit, and ensure that the organic waste gas emissions meet the standards, based on the implementation of GB 37822-2019 "Volatile Organic Compound Unorganized Emission Control Standard" and the "Odor Pollutant Emission Standard" (GB14554-2018) and "Atmospheric Pollutant Comprehensive Emission Standard" (GB16297-1996) emission standards and combined with the process characteristics, the applicant collected the organic waste gas released during the wastewater treatment process generated by the methylamine co-production DMF unit and summarized the process method, thereby achieving the waste gas emission standards. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to meet the national emission standards and optimize the surrounding environment of the device, provide a more comfortable working environment for the physical and mental health of employees, and provide a method for unified waste gas treatment of a methylamine co-production DMF device, so as to achieve the purpose of effectively controlling the organic waste gas emitted by the methylamine co-production DMF device.

[0005] The technical solution of the present invention is: a method for treating organic waste gas from a methylamine co-production DMF device, which comprises the following steps: introducing the organic waste gas generated in the wastewater of the methylamine co-production DMF device into a waste gas collection main pipe by using an induced draft fan to draw negative pressure; removing water-soluble organic matter and particulate matter from the organic waste gas by passing through a water washing tower; and subjecting the waste gas after washing in the water washing tower to acid washing and alkali washing to neutralize the acid and alkali substances in the organic waste gas, thereby removing the odor in the organic waste gas and generating inorganic salts and water; then sending the treated organic waste gas into a demister to remove moisture from the waste gas, and then using activated carbon to adsorb the organic matter; sending the treated waste gas into a deodorizing spray tower for atomization, wherein the atomized liquid combines with the odorous gas to generate coating, oxidation, and decomposition reactions, and finally converting the odorous gas into carbon dioxide, water, and inorganic salts; and finally discharging the treated waste gas that meets the standards by leading it up through a chimney.

[0006] This treatment method is mainly suitable for treating low concentrations (H2S, non-methane total hydrocarbons, ammonia, odor concentration, etc.). By analyzing the content of organic waste gas generated by the system, the data are as follows:

[0007] Table 1 Organic waste gas content of methylamine co-production DMF device

[0008] Sampling name Hydrogen sulfide (kg / h) Ammonia (kg / h) Odor concentration Total non-methane hydrocarbons (kg / h) exhaust gas 30.46 152.6 5600 126.8

[0009] Table 2 Emission indicators of the "Emission Standards for Odor Pollutants" and the "Comprehensive Emission Standards for Air Pollution"

[0010]

[0011] A device for treating organic waste gas from a methylamine co-production DMF device, the device comprising: a waste gas collecting main pipe, a water washing tower, an acid washing tower, an alkali washing tower, a demister, an activated carbon adsorption device, a deodorizing tower, and an induced draft fan, wherein the waste gas collecting main pipe, the water washing tower, the acid washing tower, the alkali washing tower, the demister, the activated carbon adsorption device, the deodorizing tower, and the induced draft fan are sequentially connected through a waste gas pipeline, and after the induced draft fan is started, the device is placed under negative pressure to introduce the organic waste gas into the waste gas collecting main pipe, and the water washing tower is provided with a water washing tower circulation device. A circulating water pump is provided, and water is sprayed from top to bottom in the tower through the water washing tower circulating water pump; the pickling tower is provided with a pickling tower circulating pump, and the acid liquid is sprayed from top to bottom in the tower through the pickling tower circulating pump; the alkali washing tower is provided with a alkali washing tower circulating pump, and the alkali liquid is sprayed from top to bottom in the tower through the alkali washing tower circulating pump; the deodorizing tower is provided with a deodorizing tower circulating pump, and the deodorizing liquid is sprayed from top to bottom in the tower through the deodorizing tower circulating pump; the induced draft fan outlet is connected to the chimney for discharging treated exhaust gas.

[0012] The water washing tower, acid washing tower, alkali washing tower, etc. are filled with two layers of fillers, all of which are made of corrosion-resistant materials; the filler support is made of stainless steel and the filler is PP ball; the filling volume in the tower is designed to be filled according to the size of the waste gas volume generated by the device. The device is designed to process 13000m3 of waste gas. 3 / h, each tower has a filling capacity of 4m 3 ; Material selection is popular, and the operating characteristics of each tower are different from pH value control.

[0013] The deodorizing liquid added to the deodorizing tower is a commercially available product. Deodorizing liquids manufactured by Shandong Wanhua Tianhe New Materials Co., Ltd., Shandong Kasong Chemical, Zike Equipment Co., Ltd., and Wuxi Yuda Fine Chemical Co., Ltd. all meet the requirements. This application uses the OS-1555 biological deodorizing liquid produced by Zike Equipment Co., Ltd., which has proven effective. Dosing method: Regularly sample and analyze odor concentration to maintain a dimensionless odor concentration of ≤2000. Deodorizing liquid is then added based on the analysis data to ensure that the odor concentration remains ≤2000 (dimensionless) and meets emission standards.

[0014] The relevant features of the present invention are as follows:

[0015] 1) According to the different components of the waste gas, the selected spray liquid, namely the acid washing tower, alkali washing tower, water washing tower, etc., is suitable for large air volume and low concentration waste gas, and the treatment efficiency can reach more than 90%

[0016] 2) There are two important sections inside the spray tower: the spray section and the demisting section. The spray section, from the spray layer to the upper end of the air inlet pipe, is the main section of the tower where gas and liquid contact and mass transfer occur. The dehydration (demisting) section, located above the nozzle, is where large droplets fall by their own weight. A demister is installed to remove small droplets, ensuring better gas-liquid separation.

[0017] 3) The waste gas contains water-soluble substances and acid and alkali waste gases. Water washing + acid washing + alkali washing is sufficient to remove these waste gases. Activated carbon adsorption is set up at the back end as a control facility to ensure stable waste gas treatment.

[0018] The present invention has the following beneficial effects: By collecting and treating organic waste gas generated by wastewater from a methylamine co-production DMF unit, the present invention significantly improves the surrounding environment and ensures compliance with emission standards, compared to uncollected and treated waste gas. Furthermore, the present invention is simple to operate, safe, and hygienic, significantly outperforming traditional wastewater and waste gas treatment processes. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 Schematic diagram of the process flow of the device of the present invention;

[0020] Markings in the figure: 1. Waste gas collection main pipe, 2. Water washing tower, 3. Water washing tower circulating water pump, 4. Pickling tower, 5. Pickling tower circulating pump, 6. Alkali washing tower, 7. Alkali washing tower circulating pump, 8. Demister, 9. Activated carbon adsorption device, 10. Deodorization tower, 11. Deodorization tower circulating pump, 12. Induced draft fan, 13. Chimney. DETAILED DESCRIPTION

[0021] See also Figure 1, start the water washing tower circulating water pump 3, water forms a spray in the tower from top to bottom; start the acid washing tower circulating pump 5, acid liquid forms a spray in the tower from top to bottom; start the alkali washing tower circulating pump 7, alkali liquid forms a spray in the tower from top to bottom; start the deodorizing tower circulating pump 11, deodorizing liquid forms a spray in the tower from top to bottom; when the water washing tower circulating pump 3, the acid washing tower circulating pump 5, the alkali washing tower circulating pump 7 and the deodorizing tower circulating pump 11 are all put into operation, open the valves of the exhaust gas pipelines of each branch line, start the induced draft fan 12 to make the equipment The waste gas from each pool in the wastewater system is collected through a branch pipe to the waste gas collection main pipe 1 and enters the water washing tower 2. The water washing tower is filled with two layers of fillers to remove most of the water-soluble organic matter and particulate matter, reducing the amount of acid and alkali washing chemicals at the back end. The washed particulate matter is mixed with water and enters the bottom water tank to be replaced by water and returned to the wastewater system for treatment; the top gas phase enters the acid washing tower 4. The acid washing tower is filled with two layers of fillers to neutralize the alkaline substances in the waste gas with the acid in the acid washing tower to generate inorganic salts and water, thereby removing part of the The malodor is separated, and the inorganic salts and water generated enter the bottom water tank and are replaced by water and returned to the wastewater system for treatment; the top gas phase enters the alkali washing tower 6, which is filled with two layers of fillers. The acidic substances in the exhaust gas react with the alkali solution in the alkali washing tower to produce acid-base neutralization reaction to generate inorganic salts and water, thereby removing part of the malodor. The generated inorganic salts and water enter the bottom water tank and are replaced by water and returned to the wastewater system for treatment; the top gas phase enters the demister 8, and the odor reduces the wind speed in the demister and contacts the baffle and wire mesh, colliding , and remove the water vapor in the exhaust gas again; the treated organic exhaust gas without moisture and dust particles enters the activated carbon adsorption box 9, and fully adsorbs organic matter under the action of activated carbon adsorption; the exhaust gas enters the deodorization tower 10, and is atomized by the deodorizing liquid. The liquid combines with the exhaust gas to produce a series of physical and chemical reactions such as oxidation and decomposition, and is converted into carbon dioxide, water and inorganic salts. The generated inorganic salts and water enter the bottom water tank and are returned to the wastewater system for treatment through water displacement; the exhaust gas that meets the standards in the top gas phase treatment is discharged high through the chimney 13.

[0022] The method of the present invention is used to collect and process waste gas for testing, and the relevant data of the third-party testing are shown in Table 3 below.

[0023] Table 3 Third-party testing data

[0024] Sampling name Hydrogen sulfide (kg / h) Ammonia (kg / h) Odor concentration Total non-methane hydrocarbons (kg / h) Exhaust gas <![CDATA[1.05*10 -4 ]]> 0.0149 1995 0.0362

Claims

1. A method for treating organic waste gas from a methylamine co-production DMF device, characterized in that: The method comprises the following steps: introducing the organic waste gas generated in the wastewater of the methylamine co-production DMF device into a waste gas collecting main pipe by using an induced draft fan to draw negative pressure; the organic waste gas is passed through a water washing tower to remove water-soluble organic matter and particulate matter; the waste gas after washing in the water washing tower is subjected to acid washing and alkali washing to neutralize the acid and alkali substances in the organic waste gas, thereby removing the odor in the organic waste gas and generating inorganic salts and water; the treated organic waste gas is then sent to a demister to remove moisture from the waste gas and then the organic matter is adsorbed by activated carbon; the treated waste gas is sent to a deodorizing spray tower for atomization, and the atomized liquid is combined with the odorous gas to generate coating, oxidation and decomposition reactions, thereby finally converting the odorous gas into carbon dioxide, water and inorganic salts; the treated waste gas that meets the standards is discharged through a chimney.

2. The method for treating organic waste gas from a methylamine co-production DMF device according to claim 1, wherein: The deodorizing liquid is added to the deodorizing tower in the following manner: by regularly sampling and analyzing, the odor concentration is controlled to be ≤2000, and the deodorizing liquid is added in time according to the analysis data to ensure that the odor concentration is ≤2000 and meets the emission standards.

3. A device for treating organic waste gas from a methylamine co-production DMF device, characterized in that: The device comprises: a waste gas collecting main pipe (1), a water washing tower (2), an acid washing tower (4), an alkali washing tower (6), a demister (8), an activated carbon adsorption device (9), a deodorizing tower (10), and an induced draft fan (12). The waste gas collecting main pipe (1), the water washing tower (2), the acid washing tower (4), the alkali washing tower (6), the demister (8), the activated carbon adsorption device (9), the deodorizing tower (10), and the induced draft fan (12) are sequentially connected through a waste gas pipeline. After the induced draft fan is started, the device is placed under negative pressure to introduce organic waste gas into the waste gas collecting main pipe. The water washing tower (2) is provided with a water washing tower circulating water pump (3 ), water is sprayed from top to bottom in the tower through the water washing tower circulating water pump (3); the acid washing tower (4) is provided with an acid washing tower circulating pump (5), and the acid liquid is sprayed from top to bottom in the tower through the acid washing tower circulating pump (5); the alkali washing tower (6) is provided with an alkali washing tower circulating pump (7), and the alkali liquid is sprayed from top to bottom in the tower through the alkali washing tower circulating pump (7); the deodorizing tower (10) is provided with a deodorizing tower circulating pump (11), and the deodorizing liquid is sprayed from top to bottom in the tower through the deodorizing tower circulating pump (11); the air outlet of the induced draft fan (12) is connected to the chimney (13) for discharging the treated waste gas.

4. The device for treating organic waste gas from a methylamine co-production DMF device according to claim 3, wherein: The water washing tower (2), acid washing tower (4) and alkali washing tower (6) are filled with two layers of fillers, all of which are made of corrosion-resistant materials; the filler support is made of stainless steel and the filler is PP ball; the filling volume in the tower is designed to be filled according to the size of the waste gas volume generated by the device. The device is designed to process 13000m3 of waste gas. 3 / h, each tower has a filling capacity of 4m 3 .

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