Chloromethane by-product dilute sulfuric acid concentration recycling device

Abstract

The utility model relates to a kind of chloromethane by-product dilute sulfuric acid concentration recycling device, including with the organic matter separation system being connected with concentration system, organic matter separation system includes sequentially connected hydrolytic kettle, organic matter thermal separation equipment, primary condenser and secondary condenser;Hydrolytic kettle is connected with chloromethane by-product dilute sulfuric acid delivery pipe, desalted water pipeline, hydrogen peroxide delivery pipe respectively, primary condenser is communicated with condensate tank, the condensate tank is communicated with hydrolytic kettle, secondary condenser is communicated with methanol recovery tank, gas phase pipeline respectively, methanol recovery tank is communicated with chloromethane synthesis device;Organic matter thermal separation equipment is communicated with dilute sulfuric acid heater, dilute sulfuric acid heater is communicated with concentration system.The utility model is concentrated before dilute sulfuric acid, first organic matter is separated out in dilute sulfuric acid, not only increase economic value, but also reduce the subsequent dilute sulfuric acid vacuum concentration system's jam risk, improve the operation stability of dilute sulfuric acid vacuum concentration system.

Description

Technical Field

[0001] This utility model belongs to the field of chloromethane by-product recycling technology, specifically relating to a device for concentrating and recycling dilute sulfuric acid, a by-product of chloromethane. Background Technology

[0002] In the production of chloromethane, methanol and hydrogen chloride are used under catalytic conditions to produce chloromethane, water, unreacted methanol, hydrogen chloride, and byproducts such as dimethyl ether and dichloromethane. During production, hydrogen chloride and most of the methanol in the chloromethane are removed through water washing and alkaline washing steps. Most of the organic matter is absorbed through a multi-stage washing reaction with concentrated sulfuric acid, and dimethyl ether, methanol, and dichloromethane are removed from the chloromethane.

[0003] The dilute sulfuric acid produced after washing with concentrated sulfuric acid contains substances such as chloromethane, dimethyl sulfate, and methyl hydrogen sulfate. If it is sold directly as a byproduct, it will pose significant environmental and safety risks.

[0004] Existing technologies typically employ mature dilute sulfuric acid vacuum concentration systems to treat dilute sulfuric acid containing large amounts of organic matter. While using these systems directly results in some organic matter being evaporated into sulfuric acid, the high temperatures cause small organic molecules to form larger ones, accumulating within the system and eventually clogging equipment, reducing operational stability, and increasing the risk of equipment damage. Furthermore, the evaporation of organic matter generates high-COD, highly acidic organic wastewater, placing a significant load on the plant's biological treatment system and increasing pollutant emissions. Utility Model Content

[0005] To overcome the shortcomings of existing technologies, this utility model provides a dilute sulfuric acid concentration and recycling device for chloromethane byproducts. This device pre-treats the dilute sulfuric acid before it enters the dilute sulfuric acid vacuum concentration system. The sulfuric acid separated from organic matter significantly reduces the amount of organic matter entering the dilute sulfuric acid vacuum concentration system, enhances the anti-clogging performance of the dilute sulfuric acid vacuum concentration system, and ensures the long-term stability of the device during operation.

[0006] The technical solution adopted in this utility model is as follows:

[0007] A device for concentrating and recycling dilute sulfuric acid, a byproduct of chloromethane production, is disclosed. The device includes an organic matter separation system connected to a concentration system. The organic matter separation system comprises a hydrolysis reactor, an organic matter thermal separation device, a primary condenser, and a secondary condenser connected in sequence. The hydrolysis reactor is connected to a dilute sulfuric acid delivery pipe, a demineralized water pipe, and a hydrogen peroxide delivery pipe, respectively. The primary condenser is connected to a condensate tank, which is also connected to the hydrolysis reactor. The secondary condenser is connected to a methanol recovery tank and a gas phase pipe, respectively. The methanol recovery tank is connected to a chloromethane synthesis unit. The organic matter thermal separation device is connected to a dilute sulfuric acid heater, which is also connected to the concentration system.

[0008] Preferably, the concentration system (dilute sulfuric acid vacuum concentration system) includes a flash tank, a first vacuum concentration vessel, a second vacuum concentration vessel, and a concentrated sulfuric acid storage tank connected in sequence. The dilute sulfuric acid heater is connected to the flash tank, the first vacuum concentration vessel and the second vacuum concentration vessel are respectively connected to a vapor phase condenser, and the vapor phase condenser is connected to an acidic wastewater storage tank.

[0009] Preferably, the organic thermal separation device is a tower structure.

[0010] Preferably, the dilute sulfuric acid transport pipe, demineralized water pipe, and hydrogen peroxide transport pipe of the chloromethane byproduct are respectively connected to the upper part of the hydrolysis reactor, the bottom of the hydrolysis reactor is connected to the upper part of the organic thermal separation equipment, and the top of the hydrolysis reactor is connected to the top of the first-stage condenser.

[0011] Preferably, the top of the organic thermal separation device is connected to the top of the primary condenser, the bottom of the organic thermal separation device is connected to the dilute sulfuric acid heater, and the lower part of the organic thermal separation device is connected to the saturated steam conveying pipe, which is also connected to the dilute sulfuric acid heater.

[0012] Preferably, the bottom of the primary condenser is connected to the top of the condensate tank, and the bottom of the condensate tank is connected to the upper part of the hydrolysis vessel via a circulating pump.

[0013] Preferably, the bottom of the primary condenser is connected to the top of the secondary condenser, the bottom of the secondary condenser is connected to the gas phase pipeline, and the gas phase pipeline is connected to the incineration device.

[0014] Preferably, the vapor phase condenser is connected to a vacuum unit, and the acidic wastewater storage tank is connected to a wastewater treatment system and a hydrolysis reactor, respectively.

[0015] Preferably, the concentrated sulfuric acid storage tank is connected to the chloromethane purification device via a concentrated sulfuric acid cooler.

[0016] Preferably, the dilute sulfuric acid heater is connected to the upper part of the flash tank, the top of the flash tank is connected to the gas phase condenser, and the bottom of the flash tank is connected to the first vacuum concentration vessel.

[0017] The working principle of this utility model is as follows:

[0018] The dilute sulfuric acid, a byproduct of chloromethane purification, is mixed with water (excluding brine or condensate from system evaporation) for hydrolysis. The concentration of the hydrolyzed dilute sulfuric acid is controlled at 40-60%, and the temperature is controlled above 50°C. 0.5-6% wt of hydrogen peroxide is added as an auxiliary agent to enhance the hydrolysis of organic matter in the dilute sulfuric acid. After hydrolysis, the dilute sulfuric acid is stripped by heating to 110-180°C. Through hydrolysis and heating stripping, methanol and dimethyl ether are separated from the dilute sulfuric acid. The sulfuric acid is then cooled to 5-10°C through two-stage condensation to recover methanol. Uncondensed dimethyl ether and other organic gases are sent to the incineration unit. The de-organized dilute sulfuric acid then enters the dilute sulfuric acid vacuum concentration system for concentration, forming 93-96% sulfuric acid that is recycled back to the chloromethane purification unit.

[0019] The beneficial effects of this utility model are as follows:

[0020] (1) Before dilute sulfuric acid is evaporated and concentrated, organic matter in dilute sulfuric acid is separated out and methanol, dimethyl ether and other substances are recycled separately, which reduces the emission of pollutants and increases economic value.

[0021] (2) Before the dilute sulfuric acid is evaporated and concentrated, the organic matter in the dilute sulfuric acid is separated first, which reduces the risk of blockage in the subsequent dilute sulfuric acid vacuum concentration system and improves the operational stability of the dilute sulfuric acid vacuum concentration system. Attached Figure Description

[0022] Figure 1 This is a schematic diagram of the structure of this utility model;

[0023] Figure 2 This is a schematic diagram of the organic matter separation system of this utility model;

[0024] Figure 3 This is a schematic diagram of the concentration system of this utility model;

[0025] Illustration:

[0026] 1. Hydrolysis vessel; 2. Organic matter thermal separation equipment; 3. Primary condenser; 4. Secondary condenser; 5. Dilute sulfuric acid delivery pipe; 6. Demineralized water pipeline; 7. Hydrogen peroxide delivery pipe; 8. Condensate tank; 9. Methanol recovery tank; 10. Incineration unit; 11. Dilute sulfuric acid heater; 12. Flash tank; 13. First vacuum concentration vessel; 14. Second vacuum concentration vessel; 15. Concentrated sulfuric acid storage tank; 16. Vapor phase condenser; 17. Acidic wastewater storage tank; 18. Steam delivery pipe; 19. Circulation pump; 20. Vacuum unit; 21. Concentrated sulfuric acid cooler. Detailed Implementation

[0027] The present invention will be further described below with reference to the accompanying drawings and specific embodiments, but the scope of protection of the present invention is not limited thereto.

[0028] Reference Figures 1-3 A device for concentrating and recycling dilute sulfuric acid, a byproduct of chloromethane, is disclosed. The device includes an organic matter separation system connected to a concentration system. The organic matter separation system comprises a hydrolysis reactor 1, an organic matter thermal separation device 2, a primary condenser 3, and a secondary condenser 4 connected in sequence. The hydrolysis reactor 1 is connected to a dilute sulfuric acid delivery pipe 5, a demineralized water pipe 6, and a hydrogen peroxide delivery pipe 7, respectively. The primary condenser 3 is connected to a condensate tank 8, which is also connected to the hydrolysis reactor 1. The secondary condenser 4 is connected to a methanol recovery tank 9 and a gas phase pipeline, respectively. The methanol recovery tank 9 is connected to a chloromethane synthesis unit. The organic matter thermal separation device 2 is connected to a dilute sulfuric acid heater 11, which is also connected to the concentration system.

[0029] The concentration system (dilute sulfuric acid vacuum concentration system) includes a flash tank 12, a first vacuum concentration vessel 13, a second vacuum concentration vessel 14, and a concentrated sulfuric acid storage tank 15 connected in sequence. The dilute sulfuric acid heater 11 is connected to the flash tank 12. The first vacuum concentration vessel 13 and the second vacuum concentration vessel 14 are respectively connected to the vapor phase condenser 16. The vapor phase condenser 16 is connected to the acidic wastewater storage tank 17.

[0030] The organic matter thermal separation equipment is a tower-type structure. It can be an enamel-lined evaporator or a combination of a distillation tower and an enamel-lined evaporator.

[0031] The dilute sulfuric acid transport pipe 5, demineralized water pipe 6, and hydrogen peroxide transport pipe 7 of the chloromethane byproduct are respectively connected to the upper part of the hydrolysis reactor 1, the bottom of the hydrolysis reactor 1 is connected to the upper part of the organic thermal separation equipment 2, and the top of the hydrolysis reactor 1 is connected to the top of the first-stage condenser 3.

[0032] The top of the organic thermal separation device 2 is connected to the top of the primary condenser 3, the bottom of the organic thermal separation device 2 is connected to the dilute sulfuric acid heater 11, and the lower part of the organic thermal separation device 2 is connected to the saturated steam conveying pipe 18, which is also connected to the dilute sulfuric acid heater 11.

[0033] The bottom of the primary condenser 3 is connected to the top of the condensate tank 8, and the bottom of the condensate tank 8 is connected to the upper part of the hydrolysis vessel 1 through the circulation pump 19.

[0034] The bottom of the primary condenser 3 is connected to the top of the secondary condenser 4, the bottom of the secondary condenser 4 is connected to the gas phase pipeline, and the gas phase pipeline is connected to the incineration device 10.

[0035] The vapor phase condenser 16 is connected to the vacuum unit 20, and the acidic wastewater storage tank 17 is connected to the sewage treatment system and the hydrolysis reactor 1.

[0036] The concentrated sulfuric acid storage tank 15 is connected to the chloromethane purification device via the concentrated sulfuric acid cooler 21.

[0037] The dilute sulfuric acid heater 11 is connected to the upper part of the flash tank 12, the top of the flash tank 12 is connected to the gas phase condenser 16, and the bottom of the flash tank 12 is connected to the first vacuum concentration vessel 13.

[0038] Dilute sulfuric acid is mixed with demineralized water or condensate evaporated from the system and introduced into hydrolysis reactor 1 to form a hydrolysis system. The ratio of water to dilute sulfuric acid is controlled to maintain the final hydrolysis concentration between 40% and 60%. Hydrogen peroxide is added during the hydrolysis process. Hydrogen peroxide promotes the decomposition of organic matter, breaking down long-chain organic compounds in the dilute sulfuric acid and reducing their molecular weight. This ensures the effectiveness of subsequent heating and separation of organic matter by dilute sulfuric acid. The amount of hydrogen peroxide added is adjusted based on the color of the hydrolyzed sulfuric acid, generally controlled between 0.5% and 6%, and the hydrolysis temperature is controlled above 50℃.

[0039] Hydrolyzed sulfuric acid enters the organic thermal separation unit 2 via pipelines or intermediate conveying equipment. This unit can use an enamel-lined evaporator or a combination of a distillation tower and an enamel-lined evaporator. The sulfuric acid in the heating tower is heated to a temperature controlled between 110 and 180°C. The dilute sulfuric acid is then evaporated and stripped, and the organic matter in the dilute sulfuric acid is evaporated into the liquid phase. The organic gas phase generated by thermal separation mixes with the organic gas phase generated by hydrolysis and enters the primary condenser 3 and the secondary condenser 4 for gas phase cooling. The outlet temperature of the primary condenser (circulating water cooling) is controlled between 40 and 80°C, and the outlet temperature of the secondary condenser (low-temperature water cooling) is controlled between 5 and 20°C. The condensate formed in the primary condenser enters the condensate tank 8. This condensate contains a small amount of methanol and can be reused in the preceding hydrolysis equipment. The secondary condenser condenses most of the methanol in the gas phase, forming 50-90% dilute methanol. This methanol can be reused in the chloromethane synthesis unit via a distillation unit. The gas phase, after undergoing two-stage cooling, contains organic compounds such as dimethyl ether and chloromethane, and is transported through pipelines to the incineration unit.

[0040] The dilute sulfuric acid separated by the organic thermal separation equipment enters the dilute sulfuric acid vacuum concentration system through pipelines. Under vacuum conditions, the boiling point of sulfuric acid is lowered. The water in the sulfuric acid is evaporated by passing through the first vacuum concentration vessel 13 and the second vacuum concentration vessel 14, and finally 93-96% concentrated sulfuric acid is recycled to the chloromethane purification device.

[0041] This invention enables the removal of most organic matter from dilute sulfuric acid before it enters the dilute sulfuric acid vacuum concentration system. It decomposes substances such as methyl sulfate and dimethyl sulfate, and extracts and recovers methanol from the organic matter, which can be reused in chloromethane synthesis. Dimethyl ether and other substances are separated and incinerated for fuel use, significantly improving economic efficiency. Furthermore, the sulfuric acid separated from organic matter greatly reduces the amount of organic matter entering the dilute sulfuric acid vacuum concentration system, enhancing its anti-clogging performance and ensuring long-term operational stability.

[0042] The above specific embodiments are used to explain and illustrate the present utility model, and are not intended to limit the present utility model. Any modifications and changes made to the present utility model within the spirit and scope of the claims shall fall within the protection scope of the present utility model.

Claims

1. A device for concentrating and recycling dilute sulfuric acid, a byproduct of chloromethane, characterized in that: The apparatus includes an organic matter separation system connected to a concentration system. The organic matter separation system comprises a hydrolysis reactor, an organic matter thermal separation device, a primary condenser, and a secondary condenser connected in sequence. The hydrolysis reactor is connected to a dilute sulfuric acid delivery pipe (a byproduct of chloromethane), a demineralized water pipe, and a hydrogen peroxide delivery pipe. The primary condenser is connected to a condensate tank, which is also connected to the hydrolysis reactor. The secondary condenser is connected to a methanol recovery tank and a gas phase pipe. The methanol recovery tank is connected to a chloromethane synthesis unit. The organic matter thermal separation device is connected to a dilute sulfuric acid heater, which is also connected to the concentration system.

2. The dilute sulfuric acid concentration and recycling device for chloromethane byproducts according to claim 1, characterized in that: The concentration system includes a flash tank, a first vacuum concentration vessel, a second vacuum concentration vessel, and a concentrated sulfuric acid storage tank connected in sequence. The dilute sulfuric acid heater is connected to the flash tank. The first vacuum concentration vessel and the second vacuum concentration vessel are respectively connected to a vapor phase condenser. The vapor phase condenser is connected to an acidic wastewater storage tank.

3. The dilute sulfuric acid concentration and recycling device for chloromethane byproducts according to claim 1, characterized in that: The organic thermal separation equipment is a tower structure.

4. The dilute sulfuric acid concentration and recycling device for chloromethane byproducts according to claim 1, characterized in that: The dilute sulfuric acid transport pipe, demineralized water pipe, and hydrogen peroxide transport pipe of chloromethane byproduct are respectively connected to the upper part of the hydrolysis reactor, the bottom of the hydrolysis reactor is connected to the upper part of the organic thermal separation equipment, and the top of the hydrolysis reactor is connected to the top of the first-stage condenser.

5. The dilute sulfuric acid concentration and recycling device for chloromethane byproducts according to claim 1, characterized in that: The top of the organic thermal separation device is connected to the top of the primary condenser, the bottom of the organic thermal separation device is connected to the dilute sulfuric acid heater, and the lower part of the organic thermal separation device is connected to the saturated steam conveying pipe, which is also connected to the dilute sulfuric acid heater.

6. The dilute sulfuric acid concentration and recycling device for chloromethane byproducts according to claim 1, characterized in that: The bottom of the primary condenser is connected to the top of the condensate tank, and the bottom of the condensate tank is connected to the upper part of the hydrolysis reactor through a circulating pump.

7. The dilute sulfuric acid concentration and recycling device for chloromethane byproducts according to claim 1, characterized in that: The bottom of the primary condenser is connected to the top of the secondary condenser, the bottom of the secondary condenser is connected to the gas phase pipeline, and the gas phase pipeline is connected to the incineration device.

8. The dilute sulfuric acid concentration and recycling device for chloromethane byproducts according to claim 2, characterized in that: The vapor phase condenser is connected to the vacuum unit, and the acidic wastewater storage tank is connected to the sewage treatment system and the hydrolysis reactor, respectively.

9. The dilute sulfuric acid concentration and recycling device for chloromethane byproducts according to claim 2, characterized in that: The concentrated sulfuric acid storage tank is connected to the chloromethane purification device via a concentrated sulfuric acid cooler.

10. The dilute sulfuric acid concentration and recycling device for chloromethane byproducts according to claim 2, characterized in that: The dilute sulfuric acid heater is connected to the upper part of the flash tank, the top of the flash tank is connected to the gas phase condenser, and the bottom of the flash tank is connected to the first vacuum concentration vessel.

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