Device for removing high sulfur content in carbon dioxide tail gas
By adopting the pre-desulfurization process of the deheavy distillation tower and the graded impurity removal process of low-pressure roughing and high-pressure refining in the treatment of carbon dioxide tail gas, the problems of multiple equipment and high cost in the treatment of high-sulfur carbon dioxide tail gas are solved, and energy conservation, emission reduction and purity improvement are achieved.
Patent Information
- Application Number
- CN202422499800.4
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2024-10-15
- Publication Date
- 2025-10-03
- Estimated Expiration
- 2034-10-15
AI Technical Summary
When treating high sulfur content in carbon dioxide tail gas, existing technologies require a large number of equipment and large investments, and the desulfurizer needs to be replaced regularly, resulting in high production and labor costs.
A desulfurization distillation tower is used to pre-desulfurize the exhaust gas. Combined with the graded impurity removal process of low-pressure crude and high-pressure refined, carbon dioxide is used as a refrigerant for cascade refrigeration, which simplifies the process route, reduces the desulfurization load of the refined desulfurization tower, and reduces the work of the compressor and the difficulty of impurity separation.
It reduces production and labor costs, simplifies process routes, saves equipment investment, improves carbon dioxide purity and extraction rate, reduces cooling loss, and has a significant energy-saving effect.
Smart Images
Figure CN223412360U_ABST
Abstract
Description
Technical Field
[0001] The utility model belongs to the technical field of carbon dioxide production, in particular to a device for removing high sulfur content in carbon dioxide tail gas. Background Art
[0002] Carbon dioxide (CO2), a carbon oxide with the chemical formula CO2 and a chemical formula weight of 44.0095, is a colorless and odorless or colorless and odorless gas at room temperature and pressure, while its aqueous solution has a slightly sour taste. It has a wide range of uses. Gaseous carbon dioxide is used in carbonating soft drinks, chemical processing, food preservation, inert protection in chemical and food processing, welding gas, and plant growth stimulant.
[0003] In summary, carbon dioxide has a wide range of uses. At the same time, the existing low-temperature methanol washing section produces a large amount of tail gas, which has the characteristics of large gas volume, low carbon dioxide purity and high sulfur content (its content range is 10 to 90 ppm). Based on this, the tail gas of the traditional low-temperature methanol washing section is vented tail gas. With the demand for carbon reduction, how to recover it has become a technical problem that needs to be solved urgently; in traditional technology, the treatment of low-sulfur carbon dioxide generally adopts a "sandwich cake" process, that is: first remove hydrogen sulfide, then remove carbonyl sulfide (hydrolysis, hydrogen sulfide is generated), and finally remove hydrogen sulfide; based on this, in order to treat carbon dioxide gas with a high sulfur content, multiple groups of "sandwich cake" processes are used in series. This method has the disadvantages of a large number of equipment, large investment, and the need to regularly replace the desulfurizer, and high production and labor costs. Utility Model Content
[0004] The purpose of the utility model is to provide a device for removing high sulfur content in carbon dioxide tail gas, so as to solve the problems raised in the above background technology.
[0005] To achieve the above objectives, the present invention provides the following technical solutions:
[0006] A device for removing high sulfur content in carbon dioxide tail gas includes a low-temperature methanol washing section, wherein the tail gas pipeline of the low-temperature methanol washing section is connected to the first inlet of a deheavy distillation tower through a first compressor and a first channel of a fourth heat exchanger, the gas phase outlet of the deheavy distillation tower is connected to the inlet of a fine desulfurization tower through the first heat exchange channel of the first heat exchanger and a booster, the gas phase outlet of the fine desulfurization tower is connected to the inlet of a delight distillation tower through the first heat exchange channel of a water cooler and the second heat exchange channel of the first heat exchanger, and the liquid phase outlet of the delight distillation tower is connected to a carbon dioxide storage tank.
[0007] The beneficial effects of the present invention are as follows: the present invention abandons the process route of treating carbon dioxide gas with high sulfur content in traditional technology, utilizes a desulfurization distillation tower to treat the vented tail gas, and pre-removes the vented tail gas, which can reduce the desulfurization load of the fine desulfurization tower without the need for graded desulfurization, greatly simplifies the process route, and reduces investment, production and labor costs; at the same time, it adopts a low-pressure roughing and high-pressure refining graded impurity removal process to reduce the work of the compressor and reduce the difficulty of impurity separation.
[0008] Preferably, the gas phase outlet of the light degassing distillation tower is connected to the first heat exchange channel of the second heat exchanger, the liquid phase outlet of the first heat exchange channel of the second heat exchanger is connected to the reflux ports of the heavy degassing distillation tower and the light degassing distillation tower respectively, the gas phase outlet of the first heat exchange channel of the second heat exchanger is connected to the first heat exchange channel of the third heat exchanger, the liquid phase outlet of the first heat exchange channel of the third heat exchanger is connected to the reflux port of the heavy degassing distillation tower, and the gas phase outlet of the first heat exchange channel of the third heat exchanger is connected to the exhaust gas treatment device.
[0009] Preferably, the liquid phase outlet of the de-heavy distillation tower is connected to a tail gas treatment device.
[0010] Preferably, a tee is provided between the liquid phase outlet of the light removal distillation tower and the carbon dioxide storage tank, the third end of the tee is connected to the second heat exchange channel of the third heat exchanger, the outlet of the second heat exchange channel of the third heat exchanger is connected to the second compressor through the second channel of the fourth heat exchanger, and the outlet of the second compressor is connected to the second inlet of the heavy removal distillation tower.
[0011] Preferably, the second heat exchange channel of the second heat exchanger is connected to the refrigerant circulation unit, which includes a booster liquefier. The booster liquefier is connected to the third channel of the fourth heat exchanger through a buffer tank, and the third channel outlet of the fourth heat exchanger is connected to the second heat exchange channel of the second heat exchanger; the second heat exchange channel outlet of the second heat exchanger is connected to the booster liquefier inlet.
[0012] Preferably, a throttle valve is provided between the third end of the tee and the second heat exchange channel of the third heat exchanger.
[0013] According to the above scheme, a device for removing high sulfur content in carbon dioxide tail gas is made, which is mainly used for desulfurizing the original vented tail gas in the low-temperature methanol washing section and purifying it to produce carbon dioxide, so that the product can be applied to industrial welding, oil field flooding, food processing and other fields; so as to achieve the advantages of energy conservation and emission reduction, saving equipment investment, reducing the use of desulfurizers and reducing production and labor costs; the utility model innovatively adopts a de-heavy distillation tower to pre-desulfurize the vented tail gas, first removes carbonyl sulfide that is easily hydrolyzed in the later stage, and on this basis removes part of hydrogen sulfide, so as to reduce the adsorption desulfurization load of the fine desulfurization tower, and does not need to adopt graded desulfurization. The method greatly simplifies the process route and reduces investment, production and labor costs. At the same time, the utility model adopts cascade refrigeration of carbon dioxide and the second refrigerant to achieve three-stage refrigeration temperature zones, and recovers the cold capacity of the cold logistics in a cascade manner, while avoiding the loss of cold capacity caused by overcooling of the hot logistics, which has a significant energy-saving effect. Furthermore, the carbon dioxide product is used as a refrigerant to create a low-temperature zone, which improves the product extraction rate. At the same time, the refrigerant carbon dioxide is returned to the distillation system after gasification, which has the characteristic of no waste of raw materials. From a macro perspective, the utility model adopts a low-pressure roughing and high-pressure refining graded impurity removal process to reduce the work done by the compressor and reduce the difficulty of impurity separation. BRIEF DESCRIPTION OF THE DRAWINGS
[0014] Figure 1 It is a structural diagram of the present utility model.
[0015] In the figure: 1. First compressor; 2. Fourth heat exchanger; 3. Heavy gas removal distillation tower; 4. First heat exchanger; 5. Booster; 6. Fine desulfurization tower; 7. Water cooler; 8. Light gas removal distillation tower; 9. Second heat exchanger; 10. Third heat exchanger; 11. Carbon dioxide storage tank; 12. Second compressor; 13. Tail gas treatment device; 14. Booster liquefier; 15. Throttle valve; 16. Buffer tank; 17. Low-temperature methanol washing section. DETAILED DESCRIPTION
[0016] The technical solutions in the embodiments of the present invention will be described clearly and completely below with reference to the accompanying drawings in the embodiments of the present invention.
[0017] Reference Figure 1As shown, the utility model is a device for removing high sulfur content in carbon dioxide tail gas, comprising a low-temperature methanol washing section 17, the tail gas pipeline of the low-temperature methanol washing section 17 is connected to the first inlet of the heavy desulfurization distillation tower 3 through the first compressor 1 and the first channel of the fourth heat exchanger 2, the gas phase outlet of the heavy desulfurization distillation tower 3 is connected to the inlet of the fine desulfurization tower 6 through the first heat exchange channel of the first heat exchanger 4 and the booster 5, the gas phase outlet of the fine desulfurization tower 6 is connected to the inlet of the light desulfurization distillation tower 8 through the first heat exchange channel of the water cooler 7 and the second heat exchange channel of the first heat exchanger 4, and the liquid phase outlet of the light desulfurization distillation tower 8 is connected to the carbon dioxide storage tank 11. The tail gas in the low-temperature methanol washing section 17 of the present invention enters the desulfurization distillation tower 3 for pre-distillation treatment on the basis of compression and heat exchange cooling, so as to remove the heavy substances in the tail gas. The heavy substances include alcohol, water, part of hydrogen sulfide, carbonyl sulfide and other impurities in the tail gas. In particular, the removal of water and carbonyl sulfide can avoid the hydrolysis of carbonyl sulfide to generate hydrogen sulfide in the later stage, thereby achieving the characteristic of avoiding the use of traditional purification methods; at the same time, the pre-distillation of the desulfurization distillation tower can reduce the desulfurization load of the fine desulfurization tower 6. The fine desulfurization tower 6 is a packed distillation tower, in which the packing in the tower can be The use of zinc oxide, activated carbon, etc. can effectively remove sulfur from the tail gas, reduce the sulfur content in the tail gas to below 0.1ppm, and can also increase the operating time of the fine desulfurization tower 6; further, the utility model has a water cooler 7 and a first heat exchanger 4 in front of the desulfurization tower 8 to exchange heat and cool the gas phase passing through the fine desulfurization tower 6 to meet the operating requirements of the desulfurization tower 8 and further improve the purity of carbon dioxide; the above-mentioned arrangement can reduce the desulfurization load of the fine desulfurization tower without the need for graded desulfurization, greatly simplify the process route, and reduce investment, production and labor costs.
[0018] Furthermore, the gas phase outlet of the de-light distillation tower 8 is connected to the first heat exchange channel of the second heat exchanger 9, the liquid phase outlet of the first heat exchange channel of the second heat exchanger 9 is respectively connected to the reflux ports of the de-heavy distillation tower 3 and the de-light distillation tower 8, the gas phase outlet of the first heat exchange channel of the second heat exchanger 9 is connected to the first heat exchange channel of the third heat exchanger 10, the liquid phase outlet of the first heat exchange channel of the third heat exchanger 10 is connected to the reflux port of the de-heavy distillation tower 3, and the gas phase outlet of the first heat exchange channel of the third heat exchanger 10 is connected to the exhaust gas treatment device 13. The utility model performs graded condensation treatment on the gas phase of the de-light distillation tower 8, recovers the condensed liquid phase, uses it as the reflux liquid of the de-heavy distillation tower 3 and the de-light distillation tower 8, and allows the non-condensable gas to enter the tail gas treatment device 13 for treatment; the above process can achieve graded condensation, which not only can achieve the characteristic of saving cooling capacity, but also can achieve full recovery and reuse of the gas phase output by the de-light distillation tower 8; the de-light distillation tower 8 described in the utility model is mainly used to remove light component impurities such as oxygen, nitrogen, hydrocarbons, carbon monoxide, etc. in the raw gas.
[0019] Furthermore, the liquid phase outlet of the deheaving distillation tower 3 is connected to the tail gas treatment device 13. The tail gas treatment device 13 mainly includes a gas-liquid separator, a catalyst, an exhaust pipe, etc., which can be directly purchased on the market, so it is not described in detail.
[0020] Furthermore, a tee is provided between the liquid phase outlet of the light-removal distillation tower 8 and the carbon dioxide storage tank 11. The third end of the tee is connected to the second heat exchange channel of the third heat exchanger 10. The outlet of the second heat exchange channel of the third heat exchanger 10 is connected to the second compressor 12 via the second channel of the fourth heat exchanger 2. The outlet of the second compressor 12 is connected to the second inlet of the heavy-removal distillation tower 3. The present invention uses carbon dioxide product as a refrigerant to create a low-temperature zone, thereby improving the product extraction rate. The refrigerant carbon dioxide is then vaporized and returned to the distillation system, eliminating raw material waste and achieving the characteristics of saving cooling capacity and reducing energy consumption.
[0021] Furthermore, the second heat exchange channel of the second heat exchanger 9 is connected to a refrigerant circulation unit, which includes a pressurized liquefier 14. The pressurized liquefier 14 is connected to the third channel of the fourth heat exchanger 2 via a buffer tank 16. The outlet of the third channel of the fourth heat exchanger 2 is connected to the second heat exchange channel of the second heat exchanger 9; the outlet of the second heat exchange channel of the second heat exchanger 9 is connected to the inlet of the pressurized liquefier 14. The present invention adopts cascade refrigeration of carbon dioxide and a second refrigerant to achieve a two-stage refrigeration temperature zone. The temperature in the second heat exchanger 9 is approximately: -22 to -14°C; the temperature in the third heat exchanger 10 is approximately: -53 to -48°C. The cold energy of the cold flow is recovered in a cascade manner, while the cold energy loss caused by overcooling of the hot flow is avoided, which has a significant energy-saving effect. The pressurized liquefier 14 described in the present invention includes a refrigeration unit, a heat exchanger, etc., which is conventional equipment and can be directly purchased on the market. The structure is not described in detail.
[0022] Furthermore, a throttle valve 15 is provided between the third end of the tee and the second heat exchange channel of the third heat exchanger 10 .
[0023] The utility model also provides a process for removing high sulfur content in carbon dioxide tail gas, which comprises the following steps:
[0024] Step 1: The tail gas in the tail gas pipeline of the low-temperature methanol washing section 17 enters the first compressor 1 for compression. The compressed tail gas enters the first channel of the fourth heat exchanger 2 for heat exchange. After heat exchange, it enters the de-weighting distillation tower 3 for distillation. The pressure of the tail gas after entering the first compressor 1 is 6 to 12 bar, and the temperature after passing through the first channel of the fourth heat exchanger 2 is 9 to 20°C.
[0025] Step 2: The tail gas enters the heavy-distillation tower 3 and undergoes mass transfer and heat exchange with the reflux liquid from the top of the tower for distillation. The light components and the vaporized gas phase of the reflux liquid after heat transfer enter the first heat exchange channel of the first heat exchanger 4 through the gas phase outlet at the top of the heavy-distillation tower 3. The heavy components removed by the heavy-distillation tower 3 mainly include alcohol, water, hydrogen sulfide, and carbonyl sulfide impurities in the feed gas. The gas phase at the top of the heavy-distillation tower 3 is carbon dioxide, the sulfur content of which is reduced to below 20 ppm, and the main component is hydrogen sulfide.
[0026] Step 3: The temperature of the gas phase after heat exchange in the first heat exchange channel of the first heat exchanger 4 is 20-40°C. The gas phase with a temperature of 20-40°C is increased to 22-32 bar by the booster 5 and then enters the fine desulfurization tower 6 for desulfurization, reducing the sulfur content in the gas phase to below 0.1 ppm;
[0027] Step 4: The gas phase after desulfurization through the fine desulfurization tower 6 enters the first heat exchange channel of the water cooler 7 for heat exchange, enters the second heat exchange channel of the first heat exchanger 4 for further heat exchange, and enters the light desulfurization distillation tower 8 for distillation; the gas phase temperature after passing through the first heat exchange channel of the water cooler 7 is 40 to 45°C, and the gas phase temperature after further heat exchange through the second heat exchange channel of the first heat exchanger 4 is -22 to -14°C;
[0028] Step 5: The raw gas entering the de-light distillation tower 8 undergoes mass transfer and heat exchange with the reflux liquid at the top of the de-light distillation tower 8. The carbon dioxide in the raw gas is continuously condensed and liquefied, enriched at the bottom of the tower, and enters the carbon dioxide storage tank 11 from the liquid phase outlet of the de-light distillation tower 8.
[0029] Furthermore, in the step 5, a portion of the liquid phase at the bottom of the light removal distillation tower 8 enters the carbon dioxide storage tank 11 through a tee, and the other portion is reduced in pressure to 6 to 9 Bar through a throttle valve 15 and then enters the second heat exchange channel of the third heat exchanger 10 as a cold source to exchange heat with the material from the first heat exchange channel of the third heat exchanger 10. After heat exchange, it enters the second channel of the fourth heat exchanger 2 for further heat exchange, and after further heat exchange, it is compressed by the second compressor 12 and enters the heavy removal distillation tower 3 for the production of carbon dioxide in the system.
[0030] Furthermore, in the step 5, the gas phase at the top of the light removal distillation tower 8 enters the first heat exchange channel of the second heat exchanger 9, and part of the gas phase is condensed and enters the heavy removal distillation tower 3 and the light removal distillation tower 8 respectively as reflux liquid; the remaining gas phase in the first heat exchange channel of the second heat exchanger 9 enters the first heat exchange channel of the third heat exchanger 10 for further condensation and liquefaction, and the condensed and liquefied liquid phase enters the heavy removal distillation tower 3 as reflux liquid, and the unliquefied gas phase in the first heat exchange channel of the third heat exchanger 10 enters the tail gas treatment device 13; the bottom liquid of the heavy removal distillation tower 3 in the step 2 also enters the tail gas treatment device 13 for treatment.
[0031] Furthermore, the refrigerant in the second heat exchange channel of the second heat exchanger 9 provides cooling capacity for the first heat exchange channel of the second heat exchanger 9 and then enters the booster liquefier 14. After being pressurized by the buffer tank 16, it enters the third channel of the fourth heat exchanger 2 for heat exchange. The refrigerant after heat exchange enters the second heat exchange channel of the second heat exchanger 9 to form a cycle; the refrigerant is R717, R134a, and R507; the refrigeration temperature of the refrigerant is -18 to -42°C.
[0032] Although the embodiments of the present invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and variations may be made to these embodiments without departing from the principles and spirit of the present invention, and the scope of the present invention is defined by the appended claims and their equivalents.
Claims
1. A device for removing high sulfur content from carbon dioxide tail gas, comprising a low-temperature methanol washing section (17), characterized in that: The tail gas pipeline of the low-temperature methanol washing section (17) is connected to the first inlet of the deheavy distillation tower (3) through the first compressor (1) and the first channel of the fourth heat exchanger (2); the gas phase outlet of the deheavy distillation tower (3) is connected to the inlet of the fine desulfurization tower (6) through the first heat exchange channel of the first heat exchanger (4) and the booster (5); the gas phase outlet of the fine desulfurization tower (6) is connected to the inlet of the delight distillation tower (8) through the first heat exchange channel of the water cooler (7) and the second heat exchange channel of the first heat exchanger (4); and the liquid phase outlet of the delight distillation tower (8) is connected to the carbon dioxide storage tank (11).
2. The device for removing high sulfur content in carbon dioxide tail gas according to claim 1, characterized in that: The gas phase outlet of the light-removal distillation tower (8) is connected to the first heat exchange channel of the second heat exchanger (9), the liquid phase outlet of the first heat exchange channel of the second heat exchanger (9) is connected to the reflux ports of the heavy-removal distillation tower (3) and the light-removal distillation tower (8), respectively, the gas phase outlet of the first heat exchange channel of the second heat exchanger (9) is connected to the first heat exchange channel of the third heat exchanger (10), the liquid phase outlet of the first heat exchange channel of the third heat exchanger (10) is connected to the reflux port of the heavy-removal distillation tower (3), and the gas phase outlet of the first heat exchange channel of the third heat exchanger (10) is connected to the tail gas treatment device (13).
3. The device for removing high sulfur content in carbon dioxide tail gas according to claim 2, characterized in that: The liquid phase outlet of the de-heavy distillation tower (3) is connected to the tail gas treatment device (13).
4. The device for removing high sulfur content in carbon dioxide tail gas according to claim 2, characterized in that: A tee is provided between the liquid phase outlet of the light-removal distillation tower (8) and the carbon dioxide storage tank (11); the third end of the tee is connected to the second heat exchange channel of the third heat exchanger (10); the outlet of the second heat exchange channel of the third heat exchanger (10) is connected to the second compressor (12) through the second channel of the fourth heat exchanger (2); and the outlet of the second compressor (12) is connected to the second inlet of the heavy-removal distillation tower (3).
5. The device for removing high sulfur content in carbon dioxide tail gas according to claim 2, characterized in that: The second heat exchange channel of the second heat exchanger (9) is connected to a refrigerant circulation unit, and the refrigerant circulation unit includes a booster liquefier (14). The booster liquefier (14) is connected to the third channel of the fourth heat exchanger (2) through a buffer tank (16). The outlet of the third channel of the fourth heat exchanger (2) is connected to the second heat exchange channel of the second heat exchanger (9); and the outlet of the second heat exchange channel of the second heat exchanger (9) is connected to the inlet of the booster liquefier (14).
6. The device for removing high sulfur content in carbon dioxide tail gas according to claim 4, characterized in that: A throttle valve (15) is provided between the third end of the tee and the second heat exchange channel of the third heat exchanger (10).