A system for hydrolyzing dimethylformamide and recovering dimethylamine

Abstract

The utility model discloses a kind of dimethylformamide hydrolysis and recover dimethylamine's system, including adjusting pH unit, for wastewater and lye mixing and adjusting pH value;Heating unit, for the wastewater after adjusting pH value heating;Hydrolysis reaction unit, with heating unit intercommunication, for the heated wastewater hydrolysis;Stripping deamination unit, with hydrolysis reaction unit intercommunication, for removing and concentrating dimethylamine in the wastewater after hydrolysis;Condensation separation unit, with the steam export of stripping deamination unit intercommunication, for dimethylamine-containing steam condensation and separation into gas phase and liquid phase;Dimethylamine absorption unit, with the gas phase export of condensation separation unit intercommunication, for absorbing gas phase dimethylamine and obtaining dimethylamine aqueous solution product;Tail gas purification unit, with the tail gas export of the dimethylamine absorption unit intercommunication.This patent's system can reduce DMF residual concentration to extremely low after wastewater treatment, create good condition for subsequent wastewater anaerobic, aerobic biochemical treatment.

Description

Technical Field

[0001] This utility model relates to the field of wastewater treatment, and in particular to a system for hydrolyzing dimethylformamide and recovering dimethylamine. Background Technology

[0002] Dimethylformamide (DMF) is miscible with water and most organic solvents, making it a commonly used solvent in chemical reactions. It is widely used in industries such as polyurethane, pharmaceuticals, dyes, and electronics. In the polyurethane industry, DMF is primarily used as a curing agent; in the pharmaceutical industry, it is mainly used as a drug synthesis intermediate; in the dye industry, it is primarily used as a dye solvent; and in the electronics industry, it is used for quenching tin-plated components and cleaning circuit boards.

[0003] DMF has a wide range of industrial applications, resulting in a large amount of DMF-containing wastewater. However, due to the toxicity of DMF and its difficulty in biodegradation, the main treatment methods for DMF-containing wastewater currently include pretreatment such as adsorption, extraction, chemical oxidation, and alkaline hydrolysis to reduce the DMF concentration to a certain level before biodegradation.

[0004] A novel extraction-distillation process (a new process for treating DMF wastewater in the pharmaceutical industry, environmental engineering) has been proposed. Using chloroform as the extractant, at a temperature of 20°C and a solvent ratio of 2, the mass fraction of the extracted DMF product is 98.87%. However, the process still suffers from problems such as low DMF yield and high energy consumption.

[0005] The invention (CN201410546709.1) proposes a pretreatment method for wastewater containing low concentrations of dimethylformamide (DMF). By adding acid to the wastewater to adjust the pH value and then reacting it for a period of time under the action of a catalyst, the DMF can be fully decomposed, thereby improving its biodegradability. Compared with alkaline hydrolysis, acid hydrolysis of DMF usually requires a higher acid concentration. Furthermore, the dimethylamine and formic acid formed by DMF hydrolysis are still toxic to microorganisms, making this method only suitable for treating wastewater containing low concentrations of DMF.

[0006] Dimethylamine (DMA), also known as aminodimethylamine or N-methylmethylamine, is a small-molecule amine organic compound. It is used as a raw material in the production of pharmaceuticals, dyes, pesticides, leather depilatories, rubber vulcanization accelerators, rocket propellants, and more. For example, in pharmaceuticals, it is used in the manufacture of phenergan, sulfonamides, and caffeine cough syrups; in pesticides, it is used in the production of thiram, amitraz, and fenvalerate; and in organic synthesis, it is used to produce dimethylformamide and dimethylhydrazine.

[0007] Since the DMF content in wastewater is usually low, DMF recovery technologies using extraction and distillation methods suffer from high energy consumption, low DMF recovery rates, and low purity of the recovered DMF. Conventional anaerobic-aerobic biochemical treatment technologies for DMF-containing wastewater are relatively simple and mature, but they require pretreatment to reduce the biotoxicity of DMF to microorganisms. This not only wastes DMF resources but also increases investment and operating costs for pretreatment equipment. Utility Model Content

[0008] The purpose of this invention is to provide a system for hydrolyzing dimethylformamide and recovering dimethylamine.

[0009] The innovation of this utility model lies in the fact that the system of this patent can reduce the residual concentration of DMF to an extremely low level (<15mg / L) after treating wastewater, effectively eliminating biological toxicity and creating favorable conditions for subsequent anaerobic and aerobic biochemical treatment of wastewater.

[0010] To achieve the aforementioned objectives, the technical solution of this utility model is: a system for hydrolyzing dimethylformamide and recovering dimethylamine, comprising...

[0011] The pH adjustment unit is used to mix wastewater with alkaline solution and adjust the pH value;

[0012] A heating unit is used to heat the wastewater after pH adjustment.

[0013] A hydrolysis reaction unit, connected to the heating unit, is used to hydrolyze the heated wastewater;

[0014] The stripping and deamination unit is connected to the hydrolysis reaction unit and is used to remove and concentrate dimethylamine in the hydrolyzed wastewater.

[0015] The condensation and separation unit is connected to the steam outlet of the stripping and deamine unit and is used to condense and separate the dimethylamine-containing steam into a gas phase and a liquid phase.

[0016] The dimethylamine absorption unit is connected to the gas phase outlet of the condensation and separation unit and is used to absorb gaseous dimethylamine and obtain dimethylamine aqueous solution product.

[0017] The exhaust gas purification unit is connected to the exhaust gas outlet of the dimethylamine absorption unit.

[0018] Furthermore, the stripping deamination unit includes a deamination tower with a deamination wastewater outlet at the bottom. A heat exchange unit is also provided between the pH adjustment unit and the heating unit. The heat exchange unit is a heat exchanger used to exchange heat between the pH-adjusted wastewater and the deamination wastewater at the deamination wastewater outlet of the stripping deamination unit.

[0019] Furthermore, the pH adjustment unit is a mixer.

[0020] Furthermore, the deaminating tower is provided with a steam inlet at the bottom, and the deaminating tower includes a lower stripping section and an upper rectification section. The stripping section is provided with a water inlet connected to the hydrolysis reaction unit, and the rectification section is provided with a steam outlet and a reflux liquid inlet.

[0021] Furthermore, the condensation separation unit includes a condenser and a gas-liquid separator. The amine-containing water vapor inlet of the condenser is connected to the steam outlet of the deamine removal tower. The condensate outlet of the condenser is connected to the condensate inlet of the gas-liquid separator. The liquid phase outlet of the gas-liquid separator is connected to the reflux liquid inlet of the deamine removal tower. The gas phase outlet of the gas-liquid separator is connected to the dimethylamine absorption unit.

[0022] Furthermore, the dimethylamine absorption unit includes an injector, a dimethylamine recovery tank, and a cooler. The inlet of the injector is connected to the gas phase outlet of the gas-liquid separator, and the dimethylamine recovery tank is connected to the outlet of the injector. The cooler is connected between the circulating liquid outlet of the dimethylamine recovery tank and the top absorption liquid inlet of the injector. The bottom of the dimethylamine recovery tank is provided with a dimethylamine aqueous solution product discharge port.

[0023] Furthermore, the exhaust gas purification unit is a purification tower, the exhaust port of the dimethylamine recovery tank is connected to the air inlet of the purification tower, and the bottom of the purification tower is provided with an absorbent liquid outlet connected to the dimethylamine recovery tank.

[0024] Furthermore, the mixer is a pipeline mixer, equipped with a wastewater raw solution inlet, a wastewater raw solution outlet, and an alkali solution inlet; the heating unit is a plate-type indirect heating heater, a shell-and-tube indirect heating heater, or a pipeline direct heating heater; the hydrolysis tower is a laminar flow tower, with an inlet at the bottom and an outlet at the top, and the inlet is connected to the heating unit; the deamination tower is a plate-type or packed distillation tower. The beneficial effects of this utility model are:

[0025] 1. The system in this invention can reduce the residual concentration of DMF to an extremely low level after treating wastewater.

[0026] (<15mg / L), effectively detoxifying the biological toxicity and creating favorable conditions for subsequent anaerobic and aerobic biochemical treatment of wastewater.

[0027] 2. This invention can recover the byproduct dimethylamine aqueous solution, thereby reducing wastewater treatment costs through waste resource utilization. Attached Figure Description

[0028] Figure 1 This is a schematic diagram of the structure of this utility model. Detailed Implementation

[0029] The technical solutions in the embodiments of this utility model will now be clearly and completely described with reference to the accompanying drawings.

[0030] Example 1: A system for hydrolyzing dimethylformamide and recovering dimethylamine, comprising...

[0031] pH adjustment unit 1 is used to mix wastewater and alkaline solution and adjust the pH value. The pH adjustment unit is a mixer, which is a pipeline mixer. The mixer is equipped with a wastewater raw solution inlet, a wastewater raw solution outlet and an alkaline solution inlet.

[0032] Heating unit 2 is used to heat the wastewater after pH adjustment. Heating unit 2 is a plate-type indirect heating heater, a shell-and-tube indirect heating heater, or a pipeline direct heating heater.

[0033] Hydrolysis reaction unit 3 is connected to heating unit 2 and is used to hydrolyze heated wastewater. The hydrolysis tower is a laminar flow tower with an inlet at the bottom and an outlet at the top. The inlet is connected to heating unit 2.

[0034] The stripping deamination unit 4 is connected to the hydrolysis reaction unit 3 and is used to remove and concentrate dimethylamine in the hydrolyzed wastewater. The stripping deamination unit 4 includes a deamination tower, which is a plate or packed distillation tower. The bottom of the deamination tower is provided with a deamination wastewater outlet and a steam inlet. The deamination tower includes a lower stripping section and an upper rectification section. The stripping section is provided with a water inlet connected to the hydrolysis reaction unit 3, and the rectification section is provided with a steam outlet and a reflux liquid inlet.

[0035] The condensation separation unit 5 is connected to the steam outlet of the stripping and deamination unit 4, and is used to condense and separate the dimethylamine-containing steam into a gas phase and a liquid phase. The condensation separation unit 5 includes a condenser 5.1 and a gas-liquid separator 5.2. The amine-containing steam inlet of the condenser 5.1 is connected to the steam outlet of the deamination tower, the condensate outlet of the condenser 5.1 is connected to the condensate inlet of the gas-liquid separator 5.2, the liquid phase outlet of the gas-liquid separator 5.2 is connected to the reflux liquid inlet of the deamination tower, and the gas phase outlet of the gas-liquid separator 5.2 is connected to the dimethylamine absorption unit 6.

[0036] The dimethylamine absorption unit 6 is connected to the gas phase outlet of the condensation and separation unit 5, and is used to absorb gaseous dimethylamine and obtain a dimethylamine aqueous solution product. The dimethylamine absorption unit 6 includes an injector 6.1, a dimethylamine recovery tank 6.2, and a cooler 6.3. The inlet of the injector 6.1 is connected to the gas phase outlet of the gas-liquid separation tank 5.2, and the dimethylamine recovery tank 6.2 is connected to the outlet of the injector 6.1. The cooler 6.3 is connected between the circulating liquid outlet of the dimethylamine recovery tank 6.2 and the top absorption liquid inlet of the injector 6.1. The bottom of the dimethylamine recovery tank 6.2 is provided with a dimethylamine aqueous solution product discharge port.

[0037] The exhaust gas purification unit 7 is connected to the exhaust gas outlet of the dimethylamine absorption unit 6. The exhaust gas purification unit 7 is a purification tower. The exhaust port of the dimethylamine recovery tank 6.2 is connected to the air inlet of the purification tower. The bottom of the purification tower is provided with an absorbent liquid outlet connected to the dimethylamine recovery tank 6.2.

[0038] Example 2: Referring to Example 1, a heat exchange unit 8 is also provided between the pH adjustment unit 1 and the heating unit 2. The heat exchange unit 8 is a heat exchanger used to exchange heat between the pH-adjusted wastewater and the deamined wastewater at the outlet of the stripping deamine unit 4.

[0039] The working principle includes the following steps:

[0040] (1) pH adjustment unit 1: Mix dimethylformamide wastewater with alkaline solution to adjust the pH value of the wastewater to 11.5-12 to obtain adjusted wastewater;

[0041] (2) Heat exchange unit 8 and heating unit 2 heat the regulated wastewater to 70-80°C and hydrolyze it in hydrolysis reaction unit 3 to obtain hydrolyzed wastewater. The hydraulic retention time is 3-4 hours.

[0042] (3) The hydrolysis wastewater is sent to the stripping and deamination unit 4 for stripping and deamination to obtain steam containing dimethylamine and deamination wastewater;

[0043] (4) The vapor containing dimethylamine is condensed and separated into gas and liquid in the dimethylamine absorption unit 6 to obtain gaseous dimethylamine and condensate. The condensate is returned to the stripping and deamination step. The gaseous dimethylamine is absorbed by a low-temperature absorption liquid to obtain a dimethylamine aqueous solution product. The tail gas generated during the absorption process is purified.

[0044] The described embodiments are merely some, not all, of the embodiments of this utility model. All other embodiments obtained by those skilled in the art based on the embodiments of this utility model without inventive effort are within the scope of protection of this utility model.

Claims

1. A system for hydrolyzing dimethylformamide and recovering dimethylamine, characterized in that, include The pH adjustment unit is used to mix wastewater with alkaline solution and adjust the pH value; A heating unit is used to heat the wastewater after pH adjustment. A hydrolysis reaction unit, connected to the heating unit, is used to hydrolyze the heated wastewater; The stripping and deamination unit is connected to the hydrolysis reaction unit and is used to remove and concentrate dimethylamine in the hydrolyzed wastewater. The condensation and separation unit is connected to the steam outlet of the stripping and deamine unit and is used to condense and separate the dimethylamine-containing steam into a gas phase and a liquid phase. The dimethylamine absorption unit is connected to the gas phase outlet of the condensation and separation unit and is used to absorb gaseous dimethylamine and obtain dimethylamine aqueous solution product. The exhaust gas purification unit is connected to the exhaust gas outlet of the dimethylamine absorption unit.

2. The system for hydrolyzing dimethylformamide and recovering dimethylamine according to claim 1, characterized in that, The stripping deamination unit includes a deamination tower with a deamination wastewater outlet at the bottom. A heat exchange unit is also provided between the pH adjustment unit and the heating unit. The heat exchange unit is a heat exchanger used to exchange heat between the pH-adjusted wastewater and the deamination wastewater at the deamination wastewater outlet of the stripping deamination unit.

3. The system for hydrolyzing dimethylformamide and recovering dimethylamine according to claim 2, characterized in that, The pH adjustment unit is a mixer.

4. The system for hydrolyzing dimethylformamide and recovering dimethylamine according to claim 3, characterized in that, The deaminating tower is equipped with a steam inlet at the bottom and includes a lower stripping section and an upper rectification section. The stripping section is equipped with a water inlet connected to the hydrolysis reaction unit, and the rectification section is equipped with a steam outlet and a reflux liquid inlet.

5. The system for hydrolyzing dimethylformamide and recovering dimethylamine according to claim 4, characterized in that, The condensation separation unit includes a condenser and a gas-liquid separator. The amine-containing water vapor inlet of the condenser is connected to the steam outlet of the deamine removal tower. The condensate outlet of the condenser is connected to the condensate inlet of the gas-liquid separator. The liquid phase outlet of the gas-liquid separator is connected to the reflux liquid inlet of the deamine removal tower. The gas phase outlet of the gas-liquid separator is connected to the dimethylamine absorption unit.

6. The system for hydrolyzing dimethylformamide and recovering dimethylamine according to claim 5, characterized in that, The dimethylamine absorption unit includes an injector, a dimethylamine recovery tank, and a cooler. The inlet of the injector is connected to the gas phase outlet of the gas-liquid separator, and the dimethylamine recovery tank is connected to the outlet of the injector. The cooler is connected between the circulating liquid outlet of the dimethylamine recovery tank and the top absorption liquid inlet of the injector. The bottom of the dimethylamine recovery tank is provided with a dimethylamine aqueous solution product discharge port.

7. The system for hydrolyzing dimethylformamide and recovering dimethylamine according to claim 6, characterized in that, The exhaust gas purification unit is a purification tower. The exhaust port of the dimethylamine recovery tank is connected to the air inlet of the purification tower. The bottom of the purification tower is provided with an absorbent liquid outlet connected to the dimethylamine recovery tank.

8. The system for hydrolyzing dimethylformamide and recovering dimethylamine according to claim 6, characterized in that, The mixer is a pipeline mixer, which has a wastewater raw liquid inlet, a wastewater raw liquid outlet and an alkali inlet; the heating unit is a plate-type indirect heating heater, a tube-type indirect heating heater or a pipeline direct heating heater; the hydrolysis tower is a laminar flow tower, with a water inlet at the bottom of the tower and a water outlet at the top, and the water inlet is connected to the heating unit; the deamination tower is a plate-type or packed distillation tower.

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