Device for treating DMAC (dimethylacetamide) wastewater

Abstract

The utility model discloses a device for treating DMAC (dimethylacetamide) wastewater, which comprises an alkaline hydrolysis reaction kettle, a feed port of the alkaline hydrolysis reaction kettle is respectively connected with an alkali storage tank and a wastewater storage tank, a discharge port of the alkaline hydrolysis reaction kettle is connected with a precipitation kettle, and a discharge port of the precipitation kettle is connected with a centrifugal machine. The DMAC wastewater treatment device is simple in structure, small in occupied area, low in energy consumption and low in equipment investment, DMAC wastewater is firstly subjected to alkaline hydrolysis treatment in the device and then subjected to precipitation treatment, the obtained wastewater treatment process is short, operation is easy, the treatment effect is good, the industrialization implementation difficulty is low, and the application value is high.

Description

Technical Field

[0001] The utility model relates to a device for treating wastewater, in particular to a device for treating DMAC wastewater, and belongs to the technical field of wastewater treatment devices. Background Art

[0002] DMAC (N,N-dimethylacetamide), as an important organic solvent, is widely used in the synthesis of various organic compounds. In recent years, with the widespread use of DMAC, research on the treatment of this type of waste has gradually deepened. Currently, the main treatment methods for wastewater containing DMAC include extraction, heat pump distillation, oxidation, and adsorption. The relevant existing technologies are as follows:

[0003] Guo Kaiwei et al. mentioned a DMAC-containing wastewater treatment device in CN213596112 U. The patent introduced that the equipment using "buffer tank, regulating tank, aeration tank, A tank, O tank and MBR membrane tank" can treat DMAC-containing wastewater, but this method is suitable for wastewater with low DMAC content, and the acclimatization of microorganisms takes time, and the system operation stability is poor.

[0004] Xing Xinzheng et al., in CN 214327069 U, describe a denitrification device for DMAC-containing wastewater. According to the patent, the device uses a "pre-reaction tank, a denitrification tank, and a transfer pump" to treat DMAC wastewater. The device primarily uses a pre-reaction + stripping method to remove DMAC from the wastewater. The reaction zone converts organic nitrogen in the DMAC into nitrogen gas, which is then removed in the stripping zone. This method is simple to operate, but is ineffective for treating low-concentration wastewater.

[0005] Chen Maolin et al. mentioned a treatment system for wastewater containing DMF and DMAC in CN 203487004 U. According to the patent, the wastewater containing DMAC can be treated with equipment such as "buffer tank, pretreatment device, dosing device, regulating tank, anaerobic ammonia oxidation tank, biological selection, biological denitrification device, sludge tank, recycled water device, and industrial water collection well". The operation process is long and the operation is relatively cumbersome. Utility Model Content

[0006] The purpose of the utility model is to provide a device for treating DMAC wastewater. The device treats DMAC wastewater through the mechanism of "alkaline hydrolysis + precipitation", has a good treatment effect on DMAC wastewater, is particularly suitable for low-concentration DMAC wastewater, and has a simple structure, easy operation, and good industrial application prospects.

[0007] In order to achieve the above purpose, the utility model adopts the following technical solutions:

[0008] A device for treating DMAC wastewater comprises an alkaline hydrolysis reactor, wherein a feed port of the alkaline hydrolysis reactor is respectively connected to an alkali storage tank and a wastewater storage tank, a discharge port of the alkaline hydrolysis reactor is connected to a precipitation reactor, and the discharge port of the precipitation reactor is connected to a centrifuge.

[0009] The device of the present invention can be used to treat DMAC wastewater of various concentrations. This DMAC wastewater is generated by the introduction of DMAC during the synthesis of new compounds. The DMAC content in the wastewater is generally ≤30%. The present device is particularly suitable for treating low-concentration DMAC wastewater with a DMAC content of ≤5%. When treating low-concentration DMAC wastewater, the device offers lower costs and greater advantages.

[0010] Furthermore, the alkaline hydrolysis reactor is provided with a gas outlet, which is connected to the absorption tower and is located at the upper part or top of the alkaline hydrolysis reactor.

[0011] Furthermore, a stirring mechanism is provided in the alkaline hydrolysis reactor.

[0012] Furthermore, the alkaline hydrolysis reactor is provided with a temperature control device.

[0013] Furthermore, a material transfer pump is provided between the alkaline hydrolysis reactor and the precipitation reactor;

[0014] Furthermore, a material transfer pump is provided between the alkali storage tank and the alkaline hydrolysis reactor;

[0015] Furthermore, a material transfer pump is provided between the wastewater storage tank and the alkaline hydrolysis reactor.

[0016] Furthermore, the precipitation kettle is provided with a solid feeding bin. The solid feeding bin is provided with a solid precipitant. The solid feeding bin is arranged on the upper part or top of the precipitation kettle.

[0017] Furthermore, a feed pipe is provided at the bottom of the solid feeding bin, and the end of the feed pipe is located at the lower part or bottom of the precipitation kettle.

[0018] Furthermore, a stirring mechanism is provided in the precipitation kettle.

[0019] Furthermore, the precipitation kettle is provided with a gas outlet, which is connected to the absorption tower. The gas outlet is located at the upper part or top of the precipitation kettle.

[0020] The utility model has the advantages of simple structure, convenient operation, small floor space, low energy consumption and small equipment investment. DMAC wastewater is firstly subjected to alkaline hydrolysis treatment in the device and then subjected to precipitation treatment. The obtained wastewater treatment process is short, the operation is simple, the treatment effect is good, the industrial implementation difficulty is low, the application value is high, and the utility model is particularly suitable for the treatment of DMAC wastewater, especially low-concentration DMAC wastewater, and has higher economic efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 This is a schematic diagram of the structure of the device for treating DMAC wastewater according to the present invention.

[0022] In the figure, 1. Alkali transfer pump; 2. Wastewater transfer pump; 3. Alkali hydrolysis reactor; 4. Absorption tower; 5. Alkali hydrolysis liquid transfer pump; 6. Solid feed bin; 7. Sedimentation tank; 8. Centrifuge; 9. Alkali storage tank; 10. Wastewater storage tank. DETAILED DESCRIPTION

[0023] The following will provide a clear and complete description of the technical solutions in the embodiments of the present invention, in conjunction with the accompanying drawings. Obviously, the described embodiments represent only a portion of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments derived by persons of ordinary skill in the art without inventive effort are within the scope of protection of the present invention. It should be noted that all directional indications (such as up, down, left, right, front, back, etc.) in the embodiments of the present invention are intended only to explain the relative positional relationships and movement of the various components in a specific posture (as shown in the accompanying drawings). If the specific posture changes, the directional indications will also change accordingly. Furthermore, the descriptions of various components or structures in the present invention are not to be construed as indicating or implying their relative importance or implicitly specifying the number of technical features indicated. Therefore, each component or structural feature may explicitly or implicitly include at least one. Furthermore, the technical solutions of the various embodiments may be combined, but only if they are achievable by persons of ordinary skill in the art. If the combination of technical solutions contradicts or is unachievable, such combination shall be deemed non-existent and outside the scope of protection claimed by the present invention.

[0024] Example 1

[0025] A device for processing DMAC wastewater, such as Figure 1 As shown, the device includes an alkaline hydrolysis reactor and a precipitation reactor that are interconnected. The alkaline hydrolysis reactor is used for alkaline hydrolysis reaction of wastewater. The alkaline hydrolysis reactor is a hollow structure with no special requirements for its shape. A feed port and a discharge port are provided on it, and the number of the feed port and the discharge port is at least one. The feed port of the alkaline hydrolysis reactor is respectively connected to the alkali storage tank and the wastewater storage tank. The alkali storage tank is filled with alkali solution required for the reaction. The alkali solution can be sodium hydroxide solution, etc. The wastewater storage tank is filled with wastewater containing DMAC. An alkali transfer pump is provided between the alkali storage tank and the alkaline hydrolysis reactor, and a wastewater transfer pump is provided between the wastewater storage tank and the alkaline hydrolysis reactor. There are no special requirements for the feeding position of the alkali solution and the wastewater. The feed can be from the upper part or top of the alkaline hydrolysis reactor, or from the lower part or bottom of the alkaline hydrolysis reactor, or as shown in the figure. Figure 1As shown in , wastewater is fed from the lower part of the alkaline hydrolysis reactor, and alkali liquor is fed from the upper part of the alkaline hydrolysis reactor. The discharge port of the alkaline hydrolysis reactor is preferably set at its bottom to facilitate material discharge. Valves are preferably set on the feed port and discharge port.

[0026] Furthermore, in order to maintain the smooth progress of the alkaline hydrolysis reaction, a stirring mechanism is provided in the alkaline hydrolysis reactor. The stirring mechanism can be selected according to the existing technology, such as a turbine stirrer, a paddle stirrer, etc. Figure 1 As shown, the stirring mechanism includes a motor and a stirring rod connected to the motor, a stirring paddle can be provided on the stirring rod, and the motor is provided on the top of the alkaline hydrolysis reactor.

[0027] Furthermore, in order to maintain the smooth progress of the alkaline hydrolysis reaction, a temperature control device can be further provided on the alkaline hydrolysis reactor. The temperature control device can be a jacket provided on the outer wall of the alkaline hydrolysis reactor. A heat medium can be passed through the jacket to maintain and control the temperature. The heat medium can be steam or thermal oil. A heating wire can also be provided in the jacket to maintain the temperature by electrical heating.

[0028] Furthermore, in the alkaline hydrolysis reaction, the wastewater and the alkali solution react in the alkaline hydrolysis reactor, and the reaction formula is: The alkaline hydrolysis reactor is provided with a gas outlet to discharge the gases generated during the reaction. The gas outlet is preferably located at the upper portion or top of the alkaline hydrolysis reactor and is connected to an absorption tower. The absorption tower is mainly used to absorb VOCs in the gas. The absorption tower is provided with a packing layer and a certain level of acid liquid. In addition, the absorption tower can also be equipped with an external circulation pump for spraying acid liquid to absorb the gas.

[0029] Further, the material in the alkaline hydrolysis reactor enters the precipitation kettle through a discharge port, and a transfer pump is provided between the alkaline hydrolysis reactor and the precipitation kettle, for pumping the alkaline hydrolysis reaction solution into the precipitation kettle. The precipitation kettle is a hollow structure, and its shape has no special requirements. The precipitation kettle is provided with a feed port, a discharge port and a gas outlet. The feed port of the precipitation kettle is preferably arranged at its top, and the feed port is connected with the discharge port of the alkaline hydrolysis reactor. The gas outlet of the precipitation kettle is preferably arranged at its top or top, for discharging gas. The gas outlet of the precipitation kettle is connected with an absorption tower, and gas is discharged by the absorption tower after being absorbed by the absorption tower, and can be directly discharged into the atmosphere. The gas inlet of the absorption tower can be one, or multiple, and the gas discharged by the alkaline hydrolysis reactor and the gas discharged by the precipitation kettle can be passed into the absorption tower respectively by pipeline, or can be brought together by pipeline and then passed into the absorption tower.

[0030] Furthermore, the precipitation kettle is provided with a solid feeding hopper, which is primarily used to add a solid precipitant to the precipitation kettle. Examples of the solid precipitant include soluble or polymeric salts of iron, aluminum, and calcium. The solid precipitant can remove dimethylamine from the wastewater. The solid feeding hopper is preferably located at the top or upper portion of the precipitation kettle and is connected to a feed port on the precipitation kettle. A feed pipe is provided at the bottom of the solid feeding hopper, the end of which is located at the lower or bottom portion of the precipitation kettle. This allows the solid precipitant to directly enter the precipitation kettle below the liquid level, thereby avoiding dust hazards in the gas phase space within the kettle.

[0031] Furthermore, a stirring mechanism is also provided in the precipitation kettle, and the stirring mechanism can be selected according to existing technologies, such as a turbine stirrer, a paddle stirrer, etc. For example, the stirring mechanism can include a motor and a stirring rod connected to the motor, and a stirring paddle can be provided on the stirring rod, and the motor is provided on the top of the precipitation kettle.

[0032] After the alkaline hydrolysis reaction liquid is fully stirred and precipitated with the solid precipitant in the precipitation kettle, the material is discharged from the discharge port of the precipitation kettle and enters a centrifuge. The feed port of the centrifuge is connected to the discharge port of the precipitation kettle. The material is centrifuged in the centrifuge, and the resulting solid material is transported to a hazardous waste storage. The water obtained by centrifugation is then washed and transferred to a sewage treatment station for treatment.

[0033] Furthermore, each alkaline hydrolysis reactor and precipitation reactor, the alkali storage tank and alkaline hydrolysis reactor, the wastewater storage tank and alkaline hydrolysis reactor, the alkaline hydrolysis reactor and the absorption tower, the precipitation tank and the absorption tower, and the precipitation tank and the centrifuge are all connected by pipelines.

[0034] The utility model is a process for treating DMAC wastewater as follows: a fixed amount of wastewater is transferred into an alkaline hydrolysis reactor via a wastewater transfer pump, stirring of the alkaline hydrolysis reactor is started, a fixed amount of alkali liquor is pumped into the alkaline hydrolysis reactor via an alkali transfer pump, a heat medium is subsequently introduced into the outer jacket of the alkaline hydrolysis reactor, the temperature of the alkaline hydrolysis reactor is raised to 40-60°C for alkaline hydrolysis treatment, the gas generated during the process is discharged through the gas outlet into an absorption tower for absorption, and the unabsorbed non-condensable gas is discharged into the atmosphere. After the reaction of the alkaline hydrolysis reactor is completed, the discharge port at the bottom of the alkaline hydrolysis reactor is opened, the alkaline hydrolysis reaction liquid is transferred into a precipitation reactor via a transfer pump, a solid precipitant is added to the precipitation reactor via a solid feeding bin, and the agitator of the precipitation reactor is started to stir to ensure that the precipitant and the alkaline hydrolysis reaction liquid are evenly mixed. The gas generated during the process is discharged through the gas outlet into the absorption tower for absorption, and the gas absorbed by the absorption tower is discharged into the atmosphere. After the reaction, the discharge port at the bottom of the precipitation kettle is opened to allow the material in the precipitation kettle to enter the centrifuge through the height difference, or it can be pumped into the centrifuge through a transfer pump. The material is centrifugally separated in the centrifuge, and the solid material obtained by centrifugation is transported to the hazardous waste storage, and the water phase obtained by centrifugation is transferred to the sewage station.

[0035] Example 2

[0036] The device described in Example 1 was used to treat wastewater generated during the synthesis of phenoxycarboxylic acid compounds. The wastewater had a DMAC concentration of 0.6%, a COD of 7019 mg / L, and a TDS of 381 mg / L. The treatment process included: starting the wastewater transfer pump 2 to pump wastewater from the wastewater storage tank 10 into the alkaline hydrolysis reactor 3. The stirring mechanism of the alkaline hydrolysis reactor was then started. Simultaneously, the alkali transfer pump 1 pumped liquid caustic soda from the alkali storage tank 9 into the alkaline hydrolysis reactor 3. The heating device of the alkaline hydrolysis reactor 3 was then started to raise the temperature within the alkaline hydrolysis reactor 3 to 40-80°C. After a certain reaction time, the DMAC in the alkaline hydrolysis reactor 3 was measured to be less than 0.1%. The bottom valve of the alkaline hydrolysis reactor 3 was opened, and the alkaline hydrolysis liquid transfer pump 5 was started to transfer the liquid into the precipitation reactor 7. After the transfer was completed, the stirring mechanism and bottom valve of the alkaline hydrolysis reactor 3 were closed. Turn on the stirring facility of the precipitation kettle 7, and at the same time open the gate valve of the solid feeding bin 6, so that the solid material therein enters the precipitation kettle 7 by gravity, adjust the speed of the precipitation kettle 7, and open the bottom valve of the kettle after the end. After the solid-liquid mixture is separated by a centrifuge, the treatment is completed.

Claims

1. A device for processing DMAC waste water, characterized in that: The invention comprises an alkaline hydrolysis reactor, wherein the feed port of the alkaline hydrolysis reactor is respectively connected with an alkali storage tank and a wastewater storage tank, the discharge port of the alkaline hydrolysis reactor is connected with a precipitation reactor, and the discharge port of the precipitation reactor is connected with a centrifuge.

2. The device according to claim 1, characterized in that: A solid feeding bin is provided on the precipitation kettle.

3. The device according to claim 2, characterized in that: A feeding pipe is provided at the bottom of the solid feeding bin, and the end of the feeding pipe is located at the lower part or bottom of the precipitation kettle.

4. The device according to claim 2 or 3, characterized in that: The solid feeding bin is arranged on the upper part or top of the precipitation kettle.

5. The device according to claim 1, 2 or 3, characterized in that: Includes at least one of the following structures: a. A transfer pump is provided between the alkaline hydrolysis reactor and the precipitation reactor; b. A transfer pump is provided between the alkali storage tank and the alkaline hydrolysis reactor; c. A transfer pump is provided between the wastewater storage tank and the alkaline hydrolysis reactor.

6. The device according to claim 1, 2 or 3, characterized in that: The alkaline hydrolysis reaction kettle and the precipitation kettle are both provided with stirring mechanisms.

7. The device according to claim 1, 2 or 3, characterized in that: The alkaline hydrolysis reactor is provided with a temperature control device.

8. The device according to claim 1, 2 or 3, characterized in that: The alkaline hydrolysis reactor is provided with a gas outlet, and the gas outlet is connected to the absorption tower.

9. The device according to claim 8, characterized in that: The gas outlet is located at the upper part or top of the alkaline hydrolysis reactor.

10. The device according to claim 1, 2 or 3, characterized in that: The precipitation kettle is provided with a gas outlet, and the gas outlet is connected to the absorption tower.

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