Treatment system for high-concentration carbon dioxide exhaust gas containing VOCs (Volatile Organic Compounds)

Abstract

The utility model relates to a treatment system for high-concentration carbon dioxide exhaust gas containing VOCs (volatile organic compounds), which aims to solve the technical problems of high cost and CO2 waste of the VOCs exhaust gas at present, and adopts the technical scheme that the treatment system comprises a gas pretreatment device, an industrial-grade liquid CO2 production device, a food-grade liquid CO2 production device and a waste gas treatment device, after being pretreated, the gas is respectively subjected to food-grade treatment and industrial-grade treatment and is purified, liquefied and rectified to generate a product, and the generated waste gas enters a direct-fired thermal oxidation furnace and a waste heat boiler to be treated and then is discharged. According to the device, the investment cost of the VOCs treatment device can be reduced, the operation energy consumption is reduced, the occupied area is reduced, industrial-grade and food-grade liquid carbon dioxide products can be produced, and the device has good popularization and application values.

Description

Technical Field

[0001] The utility model belongs to the technical field of treatment of high-concentration carbon dioxide exhaust gas containing VOCs, and specifically relates to a treatment system for high-concentration carbon dioxide exhaust gas containing VOCs. Background Art

[0002] Global climate change is having a profound impact on human survival and development, and has become a major challenge faced by all countries in the world.

[0003] In the field of coal chemical industry, low-temperature methanol washing technology is widely used in the purification process of coal-to-natural gas, coal-to-methanol, coal-to-oil, and coal-to-synthetic ammonia due to its many advantages such as high purification degree, good selectivity, and easy regeneration. The waste gas emitted by the low-temperature methanol washing device is a high-concentration carbon dioxide emission waste gas containing VOCs, with a large emission volume and small gas volume fluctuations. Among them, CO 2 The volume fraction of CO2 is usually 80-90%, while the volume fraction of VOCs is only between 1-5%.

[0004] The treatment of high-concentration carbon dioxide emissions containing VOCs is usually based on the different calorific values ​​of the exhaust gas, which is directly treated by a regenerative thermal oxidizer (RTO) or a direct-fired thermal oxidizer to meet the emission standards. Not only is there a problem of high investment and operating costs, but the carbon dioxide is not captured and recovered. Utility Model Content

[0005] The utility model aims to solve the above problems and provide a processing system for high-concentration carbon dioxide exhaust gas containing VOCs.

[0006] In order to solve the above technical problems, the technical solution adopted by the utility model is:

[0007] A system for treating high-concentration carbon dioxide exhaust gas containing VOCs, comprising a gas pre-treatment device, an industrial-grade liquid CO 2 Production equipment, food grade liquid CO 2 Production plants and waste gas treatment plants;

[0008] The gas pretreatment device comprises a raw gas pipeline, a gas-liquid buffer tank and a compressor. The high-concentration carbon dioxide exhaust gas containing VOCs is connected to the gas-liquid buffer tank through the raw gas pipeline, and the outlet of the gas-liquid buffer tank is connected to the inlet of the compressor;

[0009] The industrial grade liquid CO 2 The production device includes industrial-grade pipelines, a first purification unit, a first liquefaction unit, a first ice machine, a first distillation tower and an industrial-grade liquid CO 2The compressor outlet is connected to the inlet of the first purification unit through an industrial-grade pipeline, the outlet of the first purification unit is connected to the inlet of the first liquefaction unit, the outlet of the first liquefaction unit is connected to the inlet of the first distillation tower, and the outlet of the first distillation tower is connected to the industrial-grade liquid CO 2 The product storage tank is connected to the industrial-grade liquid CO 2 The evaporation port of the product storage tank is connected to the first purification unit, the outlet is fed into a tank truck through a pump, and the first ice machine is connected to the first liquefaction unit;

[0010] The food grade liquid CO 2 The production device includes food-grade pipelines, a second purification unit, a second liquefaction unit, a second ice machine, a second distillation tower, a third distillation tower and food-grade liquid CO 2 The compressor outlet is connected to the inlet of the second purification unit through a food-grade pipeline, the outlet of the second purification unit is connected to the inlet of the second liquefaction unit, the outlet of the second liquefaction unit is connected to the inlet of the second distillation tower, the outlet of the second distillation tower is connected to the inlet of the third distillation tower, and the outlet of the third distillation tower is connected to the food-grade liquid CO 2 The product tank is connected to the food grade liquid CO 2 The evaporation port of the product storage tank is connected to the second purification unit, the outlet is fed into a tank truck through a pump, and the second ice machine is connected to the second liquefaction unit;

[0011] The waste gas treatment device includes a waste gas pipeline, a direct-fired thermal oxidation furnace and a waste heat boiler. The tops of the first purification unit, the first distillation tower, the second purification unit, the second distillation tower and the third distillation tower are respectively connected to the direct-fired thermal oxidation furnace through the waste gas pipeline, and the direct-fired thermal oxidation furnace is connected to the waste heat boiler.

[0012] Furthermore, a first flow regulating valve is provided on the industrial-grade pipeline between the compressor and the first purification unit.

[0013] Furthermore, a second flow regulating valve is provided on the food-grade pipeline between the compressor and the second purification unit.

[0014] Furthermore, the first purification unit and the second purification unit are each provided with two parallel adsorption towers, which take turns to adsorb and purify the compressed high-concentration carbon dioxide exhaust gas containing VOCs.

[0015] Compared with the prior art, the beneficial effects of the utility model are:

[0016] 1. The utility model can not only reduce the investment cost of VOCs treatment equipment, reduce operating energy consumption, and reduce floor space, but also produce industrial-grade and food-grade liquid carbon dioxide products, and has good promotion and application value;

[0017] 2. The pipelines and equipment of the food-grade and industrial-grade production lines in the utility model are completely independent, which can realize the production of liquid carbon dioxide with different outputs and different product uses according to market demand, and will not cause the problem of industrial-grade products contaminating food-grade equipment and pipelines, thus ensuring food safety to the greatest extent;

[0018] 3. Compared with the direct-fired thermal oxidation furnace that directly treats the high-concentration carbon dioxide exhaust gas containing VOCs from the low-temperature methanol washing device, the scale of the direct-fired thermal oxidation furnace of the utility model is only 1 / 5-1 / 4 of the original one, and the investment cost and operating cost are also greatly reduced;

[0019] 4. The utility model has flow regulating valves on the two pipelines, which can adjust the output of industrial-grade products and food-grade products at any time according to the market demand for liquid carbon dioxide products to maximize benefits. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 It is a structural schematic diagram of the utility model;

[0021] In the figure: 1. Raw gas pipeline; 2. Gas-liquid buffer tank; 3. Compressor; 4. Industrial-grade pipeline; 5. First flow control valve; 6. First purification unit; 7. First liquefaction unit; 8. First ice machine; 9. First distillation tower; 10. Industrial-grade liquid CO 2 Product storage tank; 11. Food-grade pipeline; 12. Second flow control valve; 13. Second purification unit; 14. Second liquefaction unit; 15. Second ice machine; 16. Second distillation tower; 17. Third distillation tower; 18. Food-grade liquid CO 2 Product storage tank; 19. Waste gas pipeline; 20. Direct-fired thermal oxidation furnace; 21. Waste heat boiler. DETAILED DESCRIPTION

[0022] The utility model is further described below in conjunction with the accompanying drawings and embodiments.

[0023] Example 1

[0024] like Figure 1 As shown, a system for treating high-concentration carbon dioxide exhaust gas containing VOCs includes a gas pre-treatment device, an industrial-grade liquid CO 2 Production equipment, food grade liquid CO 2 Production plants and waste gas treatment plants;

[0025] The gas pretreatment device comprises a raw gas pipeline 1, a gas-liquid buffer tank 2 and a compressor 3. The high-concentration carbon dioxide exhaust gas containing VOCs is connected to the gas-liquid buffer tank 2 through the raw gas pipeline 1. The outlet of the gas-liquid buffer tank 2 is connected to the inlet of the compressor 3.

[0026] The industrial grade liquid CO 2The production device includes an industrial-grade pipeline 4, a first purification unit 6, a first liquefaction unit 7, a first ice machine 8, a first distillation tower 9 and an industrial-grade liquid CO 2 The outlet of the compressor 3 is connected to the inlet of the first purification unit 6 through an industrial-grade pipeline 4, and a first flow regulating valve 5 is provided on the industrial-grade pipeline 4. The outlet of the first purification unit 6 is connected to the inlet of the first liquefaction unit 7, and the outlet of the first liquefaction unit 7 is connected to the inlet of the first distillation tower 9. The outlet of the first distillation tower 9 is connected to the industrial-grade liquid CO 2 The product storage tank 10 is connected to the industrial-grade liquid CO 2 The evaporation port of the product storage tank 10 is connected to the first purification unit 6, and the outlet is fed into a tank truck through a pump. The first ice machine 8 is connected to the first liquefaction unit 7. The first purification unit 6 is provided with two parallel adsorption towers, which take turns to adsorb and purify the compressed high-concentration carbon dioxide exhaust gas containing VOCs. When one of the adsorption towers is saturated with adsorption, the industrial-grade liquid CO 2 The gas phase CO evaporated in the product storage tank 10 2 After being heated, it is passed into the adsorption tower for desorption and regeneration, and the regenerated gas is sent to the subsequent direct-fired thermal oxidation furnace 20 through the exhaust gas pipeline 19.

[0027] The food grade liquid CO 2 The production device includes a food-grade pipeline 11, a second purification unit 13, a second liquefaction unit 14, a second ice machine 15, a second distillation tower 16, a third distillation tower 17 and a food-grade liquid CO 2 The outlet of the compressor 3 is connected to the inlet of the second purification unit 13 through the food-grade pipeline 11, and the food-grade pipeline 11 is provided with a second flow regulating valve 12. The outlet of the second purification unit 13 is connected to the inlet of the second liquefaction unit 14, and the outlet of the second liquefaction unit 14 is connected to the inlet of the second distillation tower 16, and the outlet of the second distillation tower 16 is connected to the inlet of the third distillation tower 17, and the outlet of the third distillation tower 17 is connected to the food-grade liquid CO 2 The product storage tank 18 is connected to the food grade liquid CO 2 The evaporation port of the product storage tank 18 is connected to the second purification unit 13, and the outlet is fed into a tank truck through a pump. The second ice machine 15 is connected to the second liquefaction unit 14. The second purification unit 13 is provided with two parallel adsorption towers, which take turns to adsorb and purify the compressed high-concentration carbon dioxide exhaust gas containing VOCs, using food-grade liquid CO 2 The gas phase CO evaporated in the product storage tank 18 2 After being heated, it is passed into the adsorption tower for desorption and regeneration, and the regenerated gas is sent to the subsequent direct-fired thermal oxidation furnace 20 through the exhaust gas pipeline 19.

[0028] The waste gas treatment device includes a waste gas pipeline 19, a direct-fired thermal oxidation furnace 20 and a waste heat boiler 21. The tops of the first purification unit 6, the first distillation tower 9, the second purification unit 13, the second distillation tower 16 and the third distillation tower 17 are respectively connected to the direct-fired thermal oxidation furnace 20 through the waste gas pipeline 19, and the direct-fired thermal oxidation furnace 20 is connected to the waste heat boiler 21.

[0029] The working process of this utility model:

[0030] The VOCs-containing high-concentration carbon dioxide exhaust gas from the low-temperature methanol washing unit mainly contains low-carbon hydrocarbons such as methane and a small amount of H 2 S, COS, CO and other gases, these substances have a very low boiling point, are not easy to decompose, and have no meaning of recycling; 2 The volume fraction is as high as 80-90%, containing saturated water, and can produce liquid carbon dioxide products at low cost;

[0031] When the utility model is used, the high-concentration carbon dioxide exhaust gas containing VOCs from the low-temperature methanol washing device is pressure-regulated and enters the gas-liquid buffer tank 2 through the raw gas pipeline 1 to separate free water. The separated high-concentration carbon dioxide exhaust gas containing VOCs enters the compressor 3 to be pressurized to 2.5-3.0MPaG and then sent to the downstream industrial and food-grade liquid CO 2 Production equipment;

[0032] A portion of the gas enters the first purification unit 6 through the industrial-grade pipeline 4. The first purification unit 6 includes two parallel adsorption towers. The adsorption towers are filled with materials such as molecular sieves, activated carbon, and alumina. After removing water and other high-boiling-point components, the gas enters the first liquefaction unit 7. The two parallel adsorption towers in the first purification unit 6 take turns to adsorb and purify the compressed high-concentration carbon dioxide exhaust gas containing VOCs. When one of the adsorption towers is saturated with adsorption, the industrial-grade liquid CO 2 The gas phase CO evaporated in the product storage tank 10 2 After being heated, it is passed into the adsorption tower for desorption and regeneration. The regenerated gas is sent to the subsequent direct-fired thermal oxidation furnace 20 through the VOCs waste gas pipeline 19. In the first liquefaction unit 7, the purified high-concentration carbon dioxide gas is evaporated by the refrigerant medium to convert the gaseous CO 2 Condensed into liquid CO 2 The refrigerating medium is then gasified into a gaseous state and recycled through the first refrigeration machine 8. In the first distillation tower 9, non-condensable gases such as nitrogen, methane, and carbon monoxide are released through the pressure control valve at the top of the distillation tower and sent to the subsequent direct-fired thermal oxidation furnace 20 through the exhaust gas pipeline 19. The liquid carbon dioxide after distillation and purification is sent to the industrial-grade liquid CO 2 The product is stored in 10 tanks and pumped into tank trucks for export or use.

[0033] Another part of the compressed VOCs-containing high-concentration carbon dioxide exhaust gas enters the second purification unit 13 through the food-grade pipeline 11. The second purification unit 13 contains two parallel adsorption towers, which are equipped with molecular sieves, activated carbon, aluminum oxide and other materials. After removing water and other high-boiling point components, it enters the second liquefaction unit 14. The two parallel adsorption towers in the second liquefaction unit 14 take turns to adsorb and purify the compressed VOCs-containing high-concentration carbon dioxide exhaust gas. When one of the adsorption towers is saturated with adsorption, it uses food-grade liquid CO 2 The gas phase CO evaporated in the product storage tank 18 2 After being heated, it is passed into the adsorption tower for desorption regeneration. The regenerated gas is sent to the subsequent direct-fired thermal oxidation furnace 20 through the exhaust gas pipeline 19. In the second liquefaction unit 14, the purified high-concentration carbon dioxide gas is evaporated by the refrigerant medium to convert the gas phase CO 2 Condensed into liquid CO 2 The refrigerant is then sent to the second distillation tower 16 and the third distillation tower 17 for multi-stage distillation and purification. The refrigerant is then gasified into a gaseous state. The refrigerant is recycled through the second ice machine 15. The non-condensable gases such as nitrogen, methane, and carbon monoxide in the second distillation tower 16 and the third distillation tower 17 are discharged through the pressure control valve at the top of the distillation tower and sent to the subsequent direct-fired thermal oxidation furnace 20 through the exhaust gas pipeline 19. The liquid carbon dioxide after multiple distillation and purification is sent to the food-grade liquid CO 2 The product is stored in a tank 18 and pumped into a tank truck for export or use;

[0034] The regenerated gas and non-condensable gas from the first purification unit 6, the first distillation tower 9, the second purification unit 13, the second distillation tower 16 and the third distillation tower 17 are all low-volume, high-concentration VOCs gases. They are sent to the subsequent direct-fired thermal oxidation furnace 20 through the exhaust gas pipeline 19 for high-temperature thermal oxidation treatment, and then the by-product steam is used in the waste heat boiler 21 to achieve flue gas emission standards.

Claims

1. A system for treating high-concentration carbon dioxide exhaust gas containing VOCs, characterized in that: Including gas pre-treatment device, industrial-grade liquid CO2 production device, food-grade liquid CO2 production device and waste gas treatment device; The gas pretreatment device comprises a raw gas pipeline (1), a gas-liquid buffer tank (2) and a compressor (3); the high-concentration carbon dioxide exhaust gas containing VOCs is connected to the gas-liquid buffer tank (2) through the raw gas pipeline (1); the outlet of the gas-liquid buffer tank (2) is connected to the inlet of the compressor (3); The industrial-grade liquid CO2 production device comprises an industrial-grade pipeline (4), a first purification unit (6), a first liquefaction unit (7), a first ice machine (8), a first distillation tower (9) and an industrial-grade liquid CO2 product storage tank (10), wherein the outlet of the compressor (3) is connected to the inlet of the first purification unit (6) through the industrial-grade pipeline (4), the outlet of the first purification unit (6) is connected to the inlet of the first liquefaction unit (7), the outlet of the first liquefaction unit (7) is connected to the inlet of the first distillation tower (9), the outlet of the first distillation tower (9) is connected to the industrial-grade liquid CO2 product storage tank (10), the evaporation port of the industrial-grade liquid CO2 product storage tank (10) is connected to the first purification unit (6), the outlet is input into a tank truck through a pump, and the first ice machine (8) is connected to the first liquefaction unit (7); The food-grade liquid CO2 production device comprises a food-grade pipeline (11), a second purification unit (13), a second liquefaction unit (14), a second ice machine (15), a second distillation tower (16), a third distillation tower (17) and a food-grade liquid CO2 product storage tank (18); the outlet of the compressor (3) is connected to the inlet of the second purification unit (13) through the food-grade pipeline (11); the outlet of the second purification unit (13) is connected to the inlet of the second liquefaction unit (14); the outlet of the second liquefaction unit (14) is connected to the inlet of the second distillation tower (16); the outlet of the second distillation tower (16) is connected to the inlet of the third distillation tower (17); the outlet of the third distillation tower (17) is connected to the food-grade liquid CO2 product storage tank (18); the evaporation port of the food-grade liquid CO2 product storage tank (18) is connected to the second purification unit (13); the outlet is input into a tank truck through a pump; the second ice machine (15) is connected to the second liquefaction unit (14); The waste gas treatment device comprises a waste gas pipeline (19), a direct-fired thermal oxidation furnace (20) and a waste heat boiler (21); the tops of the first purification unit (6), the first distillation tower (9), the second purification unit (13), the second distillation tower (16) and the third distillation tower (17) are respectively connected to the direct-fired thermal oxidation furnace (20) through the waste gas pipeline (19); and the direct-fired thermal oxidation furnace (20) is connected to the waste heat boiler (21).

2. A system for treating high-concentration carbon dioxide exhaust gas containing VOCs according to claim 1, characterized in that: A first flow regulating valve (5) is provided on the industrial-grade pipeline (4) between the compressor (3) and the first purification unit (6).

3. A system for treating high-concentration carbon dioxide exhaust gas containing VOCs according to claim 1, characterized in that: A second flow regulating valve (12) is provided on the food-grade pipeline (11) between the compressor (3) and the second purification unit (13).

4. A system for treating high-concentration carbon dioxide exhaust gas containing VOCs according to claim 1, characterized in that: The first purification unit (6) and the second purification unit (13) are each provided with two parallel adsorption towers, which take turns to adsorb and purify the compressed high-concentration carbon dioxide exhaust gas containing VOCs.

Images