Low-temperature flue gas treatment system

Abstract

A low-temperature flue gas treatment system, comprising a heat exchanger (1), an absorption refrigerator (2), a spray column (3), a cooling column (4), an adsorption column (5) and a regeneration column (6). Flue gas undergoes primary cooling by means of the heat exchanger (1), subsequently drives the absorption refrigerator (2) to operate and undergoes secondary cooling; after the flue gas inside the spray column (3) exchange heat with a spray liquid, the temperature thereof is reduced below the room temperature; then the flue gas is adsorbed in the adsorption column (5) to be purified into clean flue gas; a heat exchange medium that has exchanged heat with the flue gas is used for the regeneration column (6) to regenerate an adsorbent. The flue gas first passes through the heat exchanger (1) and the absorption refrigerator (2) to undergo waste heat recovery and cooling and then enters the spray column (3), helping to reduce the cooling load of the spray column (3) and reduce energy consumption. Graded cooling of the flue gas inside the spray column (3) can improve the cooling effect of the flue gas. In addition, the use of the waste heat recovered by the heat exchanger (1) for the regeneration column (6) improves the economy of the entire system.

Description

Low temperature flue gas treatment system

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This disclosure is based on and claims the priority of Chinese patent application with application number 202410281173.9 and application date March 12, 2024. The entire content of the Chinese patent application is hereby incorporated into this disclosure by reference. Technical Field

[0003] The present disclosure relates to the technical field of adsorption purification, and in particular to a low-temperature flue gas treatment system. Background Art

[0004] Boiler flue gas contains a variety of pollutants, which need to be removed before discharge. Nitrogen compounds in flue gas are typically removed through adsorption using adsorbents. Because the adsorption process requires low temperatures, the flue gas must first be cooled to a relatively low temperature before passing it through the adsorbent for adsorption. After a period of use, the adsorbent must be regenerated, and this regeneration process requires high temperatures.

[0005] In related technologies, the cooling of flue gas and the high-temperature regeneration process of the adsorbent require high-power refrigeration and heating equipment respectively. Especially in the final stage of flue gas cooling, the temperature of the flue gas is relatively low, resulting in relatively low energy efficiency of the refrigeration equipment and high energy consumption, which seriously affects the economy of the flue gas treatment process. Summary of the Invention

[0006] The present disclosure is based on the inventors' findings and understanding of the following facts and problems:

[0007] The flue gas generated by the boiler has a relatively high temperature. During the flue gas discharge process, the flue gas temperature drops, and the flue gas's residual heat is not utilized, resulting in a large amount of waste heat. Furthermore, the adsorbent regeneration process in the regeneration tower requires a considerable amount of heat to heat the adsorbent. Therefore, the inventors considered fully utilizing the flue gas's residual heat to reduce energy waste and improve the economic efficiency of the flue gas treatment process.

[0008] The present disclosure aims to solve one of the technical problems in the related art at least to a certain extent. To this end, the present disclosure proposes a low-temperature flue gas treatment system.

[0009] The low-temperature flue gas treatment system disclosed in the present invention includes: a heat exchanger, an absorption refrigeration machine, a spray tower, a cooling tower, an adsorption tower and a regeneration tower, the heat exchanger includes a primary side pipeline and a secondary side pipeline, the primary side pipeline has an inlet and an outlet for the flue gas to be purified, the secondary side pipeline is used to pass a heat exchange medium, the heat exchange medium is used to exchange heat with the flue gas to cool the flue gas once, and the flue gas after the primary cooling is discharged from the outlet of the primary side pipeline; the absorption refrigeration machine is connected to the outlet of the primary side pipeline, the absorption refrigeration machine is driven by the flue gas after the primary cooling and realizes secondary cooling of the flue gas after the primary cooling; the spray tower includes a flue gas inlet, a first spray area, a second spray area and a flue gas outlet, the absorption system The cooling machine is connected to the flue gas inlet, and the flue gas after secondary cooling enters the spray tower through the flue gas inlet and flows through the first spray area and the second spray area in sequence to be cooled to low-temperature flue gas below room temperature and discharged through the flue gas outlet. The absorption refrigeration machine is also connected to the second spray area to cool the spray liquid in the second spray area; the cooling tower is connected to the first spray area to cool the spray liquid in the first spray area; the adsorption tower is connected to the flue gas outlet of the spray tower, and an adsorbent is provided in the adsorption tower to adsorb and purify the low-temperature flue gas into clean flue gas; the regeneration tower is connected to the secondary side pipeline so that the heat exchange medium after heat exchange with the flue gas to be purified is used to heat and regenerate the adsorbent in the regeneration tower.

[0010] In the low-temperature flue gas treatment system disclosed herein, before the flue gas to be purified is subjected to low-temperature adsorption, part of the waste heat therein is first recovered through a heat exchanger and the flue gas is cooled once, and then the flue gas after the first cooling is passed into an absorption refrigeration machine to further recover the waste heat therein and cool it a second time. After the flue gas to be purified is cooled twice, it enters the spray tower, which reduces the cooling load of the spray tower and is beneficial to reducing the energy consumption of the spray tower.

[0011] After secondary cooling, the flue gas enters the spray tower and is first spray-cooled in the first spray zone, and then further spray-cooled in the second spray zone. The spray liquid in the second spray zone is cooled by the cooling capacity generated by the absorption chiller. This staged cooling and the cooling capacity of the absorption chiller improve the flue gas cooling effect and energy utilization. The secondary cooling flue gas is spray-cooled in the spray tower to a low-temperature flue gas below room temperature. This low-temperature flue gas has a high adsorption rate in the adsorption tower, achieving a good purification effect. Furthermore, the waste heat recovered by the heat exchanger can be used to heat the regeneration tower to regenerate the adsorbent, enabling the reuse of waste heat and improving the economic efficiency of the entire system.

[0012] In some embodiments, the first spray area is provided with a first spray pipe and a first liquid collecting tank. The first spray pipe is used to spray spray liquid to spray cool the flue gas after secondary cooling. The first liquid collecting tank is used to receive the spray liquid. The cooling tower includes a liquid inlet connected to the first liquid collecting tank and a liquid outlet connected to the first spray pipe. The spray liquid in the first liquid collecting tank is cooled by the cooling tower and then transported back to the first spray pipe.

[0013] In the low-temperature flue gas treatment system disclosed herein, the first spray pipe can spray the spray liquid relatively evenly across the first spray zone, ensuring more complete contact between the spray liquid and the flue gas in the first spray zone, resulting in a better heat exchange effect for the flue gas. After heat exchange with the flue gas, the spray liquid heats up and falls into the first sump. The spray liquid in the first sump can then enter the cooling tower to exchange heat with the air, cooling the spray liquid. The cooled spray liquid is then transported back to the first spray pipe, enabling recycling and conserving the spray liquid.

[0014] In some embodiments, the second spray area is provided with a second spray pipe and a second liquid collecting tank, the absorption refrigeration machine includes an evaporator, the second spray pipe and the second liquid collecting tank are both connected to the evaporator, and the spray liquid in the second liquid collecting tank is cooled by the evaporator and then transported back to the second spray pipe.

[0015] In the low-temperature flue gas treatment system disclosed herein, the flue gas temperature has already dropped after being spray-cooled by the first spray zone. A second spray pipe is installed in the second spray zone to further spray-cool the flue gas, lowering the flue gas temperature and improving adsorption efficiency upon entering the adsorption tower. Furthermore, since the flue gas is already at a lower temperature upon entering the second spray zone, using an electric chiller would consume significant energy. Using an absorption chiller to cool the spray liquid is more energy-efficient, reducing system operating costs.

[0016] In some embodiments, the absorption chiller includes a generator, a condenser and an absorber. The generator is connected to the outlet of the primary side pipeline. The flue gas after primary cooling is used to provide heat to the generator to drive the absorption chiller. The condenser and the absorber are both connected to the liquid outlet of the cooling tower to use the spray liquid discharged from the cooling tower to cool the refrigerant in the condenser and the absorber.

[0017] In the low-temperature flue gas treatment system disclosed herein, the absorption chiller generates significant heat during operation in its condenser and absorber. Cooling these condensers and absorber with spray liquid discharged from the cooling tower enables more efficient operation of the absorption chiller. Furthermore, cooling the condenser and absorber with the cooling tower eliminates the need for separate cooling equipment for the absorption chiller, reducing overall system operating costs.

[0018] In some embodiments, the spray tower further includes a third spray area, which is located between the first spray area and the second spray area. The flue gas after secondary cooling flows through the first spray area, the third spray area and the second spray area in sequence. The third spray area is provided with a third spray pipe and a third liquid collecting tank.

[0019] The low-temperature flue gas treatment system further includes an electric refrigerator connected to the third liquid collecting tank and the third spray pipe to cool the spray liquid in the third liquid collecting tank and transport the cooled spray liquid back to the third spray pipe.

[0020] In the low-temperature flue gas treatment system disclosed herein, flue gas sequentially flows through the first, third, and second spray zones, exchanging heat with the spray liquid in each of these zones. This allows the flue gas to reach temperatures below room temperature, facilitating the subsequent low-temperature adsorption of impurities in the flue gas in the adsorption tower. Furthermore, because the flue gas is progressively cooled in the first, third, and second spray zones, the heat exchange temperature difference between the spray liquid and the flue gas is small within each spray zone, resulting in a better heat exchange effect and less evaporation loss of the spray liquid. This conserves spray liquid while achieving a better cooling effect on the flue gas.

[0021] In some embodiments, the electric refrigerator is connected to the cooling tower, and the cooling tower is used to provide cooling water to the electric refrigerator to dissipate heat from the electric refrigerator.

[0022] In the low-temperature flue gas treatment system disclosed herein, the condenser portion of the electric chiller generates significant heat during operation. Cooling water provided by the cooling tower dissipates this heat, enabling more efficient operation. Furthermore, using cooling water to dissipate heat from the chiller eliminates the need for separate heat dissipation equipment, reducing overall system operating costs.

[0023] In some embodiments, the spray tower further includes a fourth spray area, and the flue gas after secondary cooling flows through the fourth spray area, the first spray area, and the second spray area in sequence. The fourth spray area is provided with a fourth spray pipe and a fourth liquid collecting tank.

[0024] The low-temperature flue gas treatment system includes a circulation pipe connected between the fourth spray pipe and the fourth liquid collecting tank to circulate the spray liquid in the fourth spray area.

[0025] In the low-temperature flue gas treatment system disclosed herein, the flue gas, after secondary cooling, still has a relatively high temperature when it enters the spray tower in the fourth spray zone. This creates a significant temperature difference between the flue gas and the spray liquid. Part of the spray liquid evaporates into water vapor after heat exchange with the flue gas, which then exits the spray tower along with the flue gas, while the remaining spray liquid falls into the fourth collection tank. A circulation pipe is provided to transport the spray liquid from the fourth collection tank back to the fourth spray pipe, enabling the recycling of the spray liquid and conserving it.

[0026] In some embodiments, the low-temperature flue gas treatment system further includes a liquid replenishing pipe, one end of which is connected to the liquid inlet of the cooling tower for replenishing spray liquid into the cooling tower.

[0027] In the low-temperature flue gas treatment system disclosed herein, the spray liquid will experience evaporation losses during heat exchange with air in the cooling tower. Therefore, a refill pipe is provided to replenish the spray liquid in a timely manner, thereby ensuring a good spray cooling effect on the flue gas.

[0028] In some embodiments, the low-temperature flue gas treatment system includes a spray liquid treatment device, which is provided on the liquid infusion pipe and is used to adjust the pH value of the spray liquid flowing through the liquid infusion pipe.

[0029] In the low-temperature flue gas treatment system disclosed herein, the spray liquid undergoes heat exchange with the gas, causing changes in pH and the incorporation of impurities carried by the gas. This can easily lead to corrosion of the delivery pipeline during the spray liquid delivery process. The provision of a spray liquid treatment device can neutralize the supplied spray liquid and remove impurities, reducing the extent of corrosion caused by the spray liquid to the delivery pipeline, extending the service life of the delivery pipeline, and reducing system maintenance costs.

[0030] In some embodiments, the spray tower includes a packing layer, and the packing layer is arranged in the first spray zone and the second spray zone.

[0031] In the low-temperature flue gas treatment system disclosed herein, a packing layer is provided in the spraying area, so that the flue gas can be more evenly distributed in the spraying area when passing through the packing layer, with a larger contact area with the spray liquid, and has a better spray cooling effect. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] FIG1 is a schematic diagram of Example 1 of a low-temperature flue gas treatment system disclosed herein.

[0033] FIG2 is a partial schematic diagram of Example 1 of the low-temperature flue gas treatment system disclosed herein.

[0034] FIG3 is a schematic diagram of Example 2 of the low-temperature flue gas treatment system disclosed herein.

[0035] FIG4 is a partial schematic diagram of Example 2 of the low-temperature flue gas treatment system disclosed herein.

[0036] FIG5 is a schematic diagram of Example 3 of the low-temperature flue gas treatment system disclosed herein.

[0037] FIG6 is a partial schematic diagram of Example 3 of the low-temperature flue gas treatment system disclosed herein.

[0038] FIG7 is a schematic structural diagram of an absorption chiller of the low-temperature flue gas treatment system of the present disclosure.

[0039] Reference numerals: 1, heat exchanger; 11, primary side pipeline; 12, secondary side pipeline; 2, absorption refrigerator; 21, generator; 22, Condenser; 23. Evaporator; 24. Absorber; 3. Spray tower; 31. Flue gas inlet; 32. Flue gas outlet; 33. First spray zone; 331. First spray pipe; 332. First collecting tank; 34. Second spray zone; 341. Second spray pipe; 342. Second collecting tank; 35. Third spray zone; 351. Third spray pipe; 352. Third collecting tank; 36. Fourth spray zone; 361. Fourth spray pipe; 362. Fourth collecting tank; 37. Packing layer; 4. Cooling tower; 41. Liquid inlet; 42. Liquid outlet; 5. Adsorption tower; 6. Regeneration tower; 7. Electric refrigerator; 8. Circulation pipe; 9. Liquid replenishment pipe; 10. Spray liquid treatment device. DETAILED DESCRIPTION

[0040] The embodiments of the present disclosure are described in detail below, and examples of the embodiments are shown in the accompanying drawings. The embodiments described below with reference to the accompanying drawings are exemplary and intended to be used to explain the present disclosure, but should not be understood as limiting the present disclosure.

[0041] As shown in FIG. 1 to FIG. 6 , the low-temperature flue gas treatment system of the embodiment of the present disclosure includes a heat exchanger 1 , an absorption refrigerator 2 , a spray tower 3 , a cooling tower 4 , an adsorption tower 5 and a regeneration tower 6 .

[0042] The heat exchanger 1 includes a primary side pipeline 11 and a secondary side pipeline 12. The primary side pipeline 11 has an inlet and an outlet for the flue gas to be purified. The secondary side pipeline 12 is used to introduce a heat exchange medium. The heat exchange medium is used to exchange heat with the flue gas to cool the flue gas once. The flue gas after the first cooling is discharged from the outlet of the primary side pipeline 11.

[0043] Specifically, the heat exchanger 1 can be a partition-type heat exchanger 1, and the heat exchange medium can be air. The flue gas to be purified is introduced into the heat exchanger 1 from the inlet of the primary side pipeline 11, and the air is introduced into the heat exchanger 1 from the inlet of the secondary side pipeline 12, and the two perform heat exchange in the heat exchanger 1. The flue gas is discharged from the outlet of the primary side pipeline 11 and is cooled once, and the air is discharged from the outlet of the secondary side pipeline 12 with the temperature increased. The heat exchanger 1 recovers the waste heat of the flue gas to be purified and cools the flue gas once, reducing the load of the spray tower 3 to cool the flue gas. At the same time, the hot air at the outlet of the secondary side pipeline 12 can be used in the regeneration tower 6 to regenerate the adsorbent, saving the energy required to heat the adsorbent and improving the economy of the entire system.

[0044] The absorption chiller 2 is connected to the outlet of the primary pipeline 11. It is driven by the flue gas after primary cooling and provides secondary cooling for the flue gas. The flue gas, still at a relatively high temperature after primary cooling in the heat exchanger 1, is passed into the absorption chiller 2 to drive it. This process further lowers the flue gas temperature, reducing the load on the spray tower 3 to cool the flue gas. Furthermore, the cooling energy generated by the absorption chiller 2 can be used to cool the spray liquid within the spray tower 3, improving the overall system's economic efficiency.

[0045] The spray tower 3 includes a flue gas inlet 31, a first spray area 33, a second spray area 34 and a flue gas outlet 32. The absorption refrigeration machine 2 is connected to the flue gas inlet 31. The flue gas after secondary cooling enters the spray tower 3 through the flue gas inlet 31 and flows through the first spray area 33 and the second spray area 34 in sequence to be cooled to low-temperature flue gas below room temperature and discharged through the flue gas outlet 32. The absorption refrigeration machine 2 is also connected to the second spray area 34 for cooling the spray liquid in the second spray area 34.

[0046] Specifically, the flue gas inlet 31 is located at the lower portion of the spray tower 3, the flue gas outlet 32 ​​is located at the upper portion of the spray tower 3, and the first spray zone 33 and the second spray zone 34 are located between the flue gas inlet 31 and the flue gas outlet 32. In the first spray zone 33 and the second spray zone 34, the spray liquid is sprayed downward, and the flue gas, which has undergone secondary cooling, flows upward and exchanges heat with the spray liquid.

[0047] After the secondary cooling, the flue gas can enter the spray tower 3 and continue to cool down until the temperature reaches below room temperature. In the spray tower 3, the flue gas flows through the first spray zone 33 and the second spray zone 34 in sequence. The temperature of the flue gas in the first spray zone 33 is relatively high. After heat exchange with the spray liquid, the temperature of the spray liquid rises to a high level. The spray liquid can be cooled by a cooling tower, an electric refrigerator, or the like. After the flue gas passes through the spray cooling treatment in the first spray zone 33, the temperature is relatively low when it flows into the second spray zone 34. In the second spray zone 34, the flue gas needs to be further cooled to below room temperature. In the second spray zone 34, an absorption refrigerator 2 is used to cool the spray liquid. Compared with the use of an electric refrigerator, this saves a lot of electricity and improves the economic efficiency of the system.

[0048] The cooling tower 4 is connected to the first spraying area 33 and is used to cool the spray liquid in the first spraying area 33. Specifically, the spray liquid after heat exchange with the flue gas in the first spraying area 33 can be transported to the cooling tower 4 for cooling, and the cooled spray liquid is transported back to the first spraying area 33 to spray cool the flue gas.

[0049] The adsorption tower 5 is connected to the flue gas outlet 32 ​​of the spray tower 3. An adsorbent is provided in the adsorption tower 5 to adsorb and purify the low-temperature flue gas into clean flue gas; the regeneration tower 6 is connected to the secondary side pipeline 12 so that the heat exchange medium after heat exchange with the flue gas to be purified is used to heat the adsorbent in the regeneration tower 6.

[0050] After three cooling steps, the flue gas becomes low-temperature flue gas below room temperature. The low-temperature flue gas contacts the adsorbent in the adsorption tower 5, resulting in a better adsorption effect and more complete impurity removal. The low temperature is room temperature or below, optionally below zero degrees Celsius, and optionally -20°C to -15°C.

[0051] After a period of adsorption, the adsorbent enters the regeneration tower 6. Hot air from the secondary side pipeline 12 enters the regeneration tower 6, heating the adsorbent in the regeneration tower 6 to release impurities from the adsorbent. The adsorbent is then regenerated and can be reused. This process not only saves energy but also reduces adsorbent costs, improving the economic efficiency of the entire system.

[0052] In the low-temperature flue gas treatment system of the embodiment of the present disclosure, before the flue gas to be purified is subjected to low-temperature adsorption, part of the waste heat therein is first recovered through a heat exchanger and the flue gas is cooled once, and then the flue gas after the first cooling is passed into an absorption refrigeration machine to further recover the waste heat therein and cool it a second time. After the flue gas to be purified is cooled twice, it enters the spray tower, which reduces the cooling load of the spray tower and is beneficial to reducing the energy consumption of the spray tower.

[0053] After secondary cooling, the flue gas enters the spray tower and is first spray-cooled in the first spray zone, and then further spray-cooled in the second spray zone. The spray liquid in the second spray zone is cooled by the cooling capacity generated by the absorption chiller. This staged cooling and the cooling capacity of the absorption chiller improve the flue gas cooling effect and energy utilization. The secondary cooling flue gas is spray-cooled in the spray tower to a low-temperature flue gas below room temperature. This low-temperature flue gas has a high adsorption rate in the adsorption tower, achieving a good purification effect. Furthermore, the waste heat recovered by the heat exchanger can be used to heat the regeneration tower to regenerate the adsorbent, enabling the reuse of waste heat and improving the economic efficiency of the entire system.

[0054] In some embodiments, as shown in Figures 1 to 6, the first spray area 33 is provided with a first spray pipe 331 and a first liquid collecting tank 332. The first spray pipe 331 is used to spray spray liquid to spray cool the flue gas after secondary cooling. The first liquid collecting tank 332 is used to receive the spray liquid. The cooling tower 4 includes a liquid inlet 41 connected to the first liquid collecting tank 332 and a liquid outlet 42 connected to the first spray pipe 331. The spray liquid in the first liquid collecting tank 332 is cooled by the cooling tower 4 and then transported back to the first spray pipe 331.

[0055] Specifically, the first spray zone 33 is located at the bottom of the spray tower 3, and the first spray pipe 331 is located above the first liquid collecting tank 332. The first spray pipe 331 sprays spray liquid to spray-cool the flue gas. After the spray liquid exchanges heat with the flue gas, it falls into the first liquid collecting tank 332. The liquid inlet 41 is located at the top of the cooling tower 4, and the liquid outlet 42 is located at the bottom of the cooling tower 4. The spray liquid in the first liquid collecting tank 332 enters the cooling tower 4 and exchanges heat with the air therein. After the heat exchange, the temperature of the spray liquid decreases and it is then transported back to the first spray pipe 331, thus achieving the recycling of the spray liquid and saving the spray liquid.

[0056] In the first spraying area 33, the temperature of the flue gas is relatively high, and part of the spray liquid directly evaporates during the heat exchange with the flue gas and is discharged from the flue gas outlet 32 ​​along with the flue gas. This part of the spray liquid takes away the heat of the flue gas by latent heat, and the other part of the spray liquid falls into the first collecting tank 332. The temperature of the spray liquid in the first collecting tank 332 is relatively high, and it is more economical to cool it through the cooling tower 4.

[0057] In some embodiments, as shown in Figures 1 to 6, the second spray area 34 is provided with a second spray pipe 341 and a second liquid collecting tank 342. The absorption refrigerator 2 includes an evaporator 23. The second spray pipe 341 and the second liquid collecting tank 342 are both connected to the evaporator 23. The spray liquid in the second liquid collecting tank 342 is cooled by the evaporator 23 and then transported back to the second spray pipe 341.

[0058] The second spray zone 34 is located above the first spray zone 33. The second spray pipe 341 is located above the second liquid collecting tank 342. The second spray pipe 341 sprays spray liquid to cool the flue gas. After exchanging heat with the flue gas, the spray liquid falls into the second liquid collecting tank 342. The spray liquid in the second liquid collecting tank 342 can be transported to the evaporator 23 of the absorption chiller 2. In the evaporator 23, the refrigerant evaporates and removes heat from the spray liquid, thereby cooling the spray liquid. The cooled spray liquid is then transported back to the second spray pipe 341, completing the spray liquid circulation.

[0059] After the flue gas is sprayed and cooled in the first spray zone 33 , its temperature has dropped. A second spray pipe 341 is provided in the second spray zone 34 to spray and cool the flue gas again, so that the flue gas reaches a lower temperature and has a better adsorption effect after entering the adsorption tower 5 .

[0060] In the second spray zone 34, the flue gas must be ultimately cooled to a set temperature, requiring a relatively low spray liquid temperature. Given the same cooling range, the lower the final cooling temperature achieved by an electric chiller, the more electricity it consumes. Therefore, using an electric chiller to cool the spray liquid in the second spray zone 34 consumes a significant amount of electricity. Using an absorption chiller 2, however, avoids this problem, conserving the electricity required to cool the spray liquid in the second spray zone 34 and improving system efficiency.

[0061] In some embodiments, as shown in Figures 1 to 6, the absorption chiller 2 includes a generator 21, a condenser 22 and an absorber 24. The generator 21 is connected to the outlet of the primary side pipeline 11. The flue gas after the primary cooling is used to provide heat to the generator 21 to drive the absorption chiller 2. The condenser 22 and the absorber 24 are both connected to the liquid outlet of the cooling tower 4 to use the spray liquid discharged from the cooling tower 4 to cool the refrigerant in the condenser 22 and the absorber 24.

[0062] Specifically, as shown in FIG7 , the absorption chiller 2 includes a working fluid pair. For example, a water-lithium bromide working fluid pair is used. A lithium bromide aqueous solution is contained in the generator 21. The flue gas at the outlet of the primary side pipeline 11 can heat the generator 21, causing the water in the lithium bromide aqueous solution to evaporate into water vapor. The water vapor enters the condenser 22, where cooling water provided by the liquid outlet 42 of the cooling tower 4 cools the condenser 22, condensing the water vapor into liquid water. The liquid water can then be throttled down to the evaporation pressure and enter the evaporator 23. The liquid water evaporates in the evaporator 23 while absorbing heat from the spray liquid, thereby cooling the spray liquid in the second spray zone 34. After the water in the generator 21 evaporates, it becomes a concentrated lithium bromide solution, which can enter the absorber 24 after throttling. In the absorber 24, the concentrated lithium bromide solution is mixed with the water vapor from the evaporator 23. The concentration of the lithium bromide solution is restored after absorbing the water vapor. The heat released in this process is taken away by the cooling water from the cooling tower 4. Finally, the lithium bromide is easily pumped back to the generator 21, and the entire absorption refrigeration process is circulated in this way.

[0063] During the above process, the absorption chiller 2 cools the spray liquid in the second spray zone 34, eliminating the need for a high-power electric chiller and saving energy. Furthermore, the existing cooling tower 4 provides cooling water to cool the condenser 22 and absorber 24, eliminating the need for other heat dissipation equipment to dissipate heat from the absorption chiller 2 and reducing overall system operating costs.

[0064] In some embodiments, as shown in Figures 3 and 4, the spray tower 3 also includes a third spray area 35, which is located between the first spray area 33 and the second spray area 34. The flue gas after secondary cooling flows through the first spray area 33, the third spray area 35 and the second spray area 34 in sequence. The third spray area 35 is provided with a third spray pipe 351 and a third collecting tank 352. The low-temperature flue gas treatment system also includes an electric refrigerator 7, which is connected to the third collecting tank 352 and the third spray pipe 351 to cool the spray liquid in the third collecting tank 352 and the cooled spray liquid is transported back to the third spray pipe 351.

[0065] Specifically, the third spray zone 35 is located in the middle of the spray zone, and the third spray pipe 351 is located above the third liquid collecting tank 352. The third spray pipe 351 sprays spray liquid to cool the flue gas. After heat exchange with the flue gas, the spray liquid falls into the third liquid tank 352. The spray liquid in the third liquid collecting tank 352 can be transported to the electric refrigerator 7 for cooling. After cooling, the spray liquid is returned to the third spray pipe 351 to complete the cycle. The flue gas flows through the first spray zone 33, the third spray zone 35, and the second spray zone 34 in sequence, exchanging heat with the spray liquid, reaching a lower temperature, which is beneficial for the subsequent adsorption of impurities in the flue gas. In addition, because the flue gas is cooled step by step in the first spray zone 33, the third spray zone 35, and the second spray zone 34, the heat exchange temperature difference between the spray liquid and the flue gas is small in each spray zone, resulting in a better heat exchange effect and less evaporation loss of the spray liquid. This saves spray liquid and effectively cools the flue gas.

[0066] In some embodiments, as shown in Figures 3 and 4, the electric refrigerator 7 is connected to a cooling tower 4, which is used to provide cooling water to the electric refrigerator 7 to dissipate heat from the electric refrigerator 7. Specifically, the cooling water from the liquid outlet 42 of the cooling tower 4 can dissipate heat from the electric refrigerator 7, for example, from the condensing device of the electric refrigerator 7. This arrangement eliminates the need for additional cooling equipment to dissipate heat from the electric refrigerator 7, thereby reducing the operating cost of the entire system and achieving better economic efficiency.

[0067] In some embodiments, as shown in Figures 5 and 6, the spray tower 3 also includes a fourth spray area 36. The flue gas after secondary cooling flows through the fourth spray area 36, ​​the first spray area 33 and the second spray area 34 in sequence. The fourth spray area 36 is provided with a fourth spray pipe 361 and a fourth collecting tank 362. The low-temperature flue gas treatment system includes a circulation pipe 8, which is connected between the fourth spray pipe 361 and the fourth collecting tank 362 to circulate the spray liquid in the fourth spray area 36.

[0068] Specifically, the fourth spray pipe 361 is located above the fourth liquid collecting tank 362. The fourth spray pipe 361 sprays spray liquid to cool the flue gas. The spray liquid exchanges heat with the flue gas and falls into the fourth liquid collecting tank 362. The spray liquid in the fourth liquid collecting tank 362 is transported back to the fourth spray pipe 361 through the circulation pipe 8. The temperature of the flue gas in the fourth spray zone 36 is relatively high. When it comes into contact with the spray liquid, the spray liquid evaporates and cools the flue gas by latent heat. The evaporated spray liquid is discharged from the flue gas outlet 32 ​​along with the flue gas. The purpose of providing the circulation pipe 8 is to realize the circulation of the spray liquid in the fourth spray zone 36. At the same time, the fourth spray zone 36 has a pre-cooling effect on the flue gas, reducing the cooling load of the first spray zone 33 and the second spray zone 34, and reducing the energy consumption of the system.

[0069] In some embodiments, as shown in Figures 1-6 , the low-temperature flue gas treatment system further includes a liquid replenishment pipe 9 and a spray liquid treatment device 10. One end of the liquid replenishment pipe 9 is connected to the liquid inlet of the cooling tower 4 and is used to replenish the spray liquid into the cooling tower 4. The spray liquid treatment device 10 is provided on the liquid replenishment pipe 9 and is used to adjust the pH value of the spray liquid flowing through the liquid replenishment pipe 9.

[0070] Specifically, the liquid replenishment pipe 9 can be connected between the liquid inlet 41 of the cooling tower 4 and the first liquid collecting tank 332 to replenish the spray liquid in the first liquid collecting tank 332 to the cooling tower 4. During the replenishment process, the pH value of the spray liquid is adjusted by the spray liquid treatment device 10. In addition, clean spray liquid can be directly replenished into the cooling tower 4 through the liquid replenishment pipe 9 without passing through the spray liquid treatment device 10, which can also achieve the purpose of replenishing the spray liquid and adjusting its pH value.

[0071] Since the spray liquid experiences evaporation losses in both the spray tower 3 and the cooling tower 4, a replenishment pipe 9 is provided to replenish the spray liquid. Furthermore, the spray liquid's pH changes after heat exchange with the flue gas, and it may also incorporate impurities carried by the flue gas, which can easily corrode the pipeline during transportation. Therefore, a spray liquid treatment device 10 is provided to neutralize the replenished spray liquid and remove impurities.

[0072] In some embodiments, as shown in FIG. 1 to FIG. 6 , the spray tower 3 includes a packing layer 37 , which is disposed in the first spray zone 33 and the second spray zone 34 .

[0073] As shown in Figures 1 and 2, a packing layer 37 is provided between the first spray pipe 331 and the first liquid collecting tank 332, and between the second spray pipe 341 and the second liquid collecting tank 342. The packing layer makes the smoke more evenly distributed in the spray area, increases the contact area with the spray liquid, and achieves better heat exchange effect.

[0074] In other embodiments, as shown in Figures 3 and 4 , a packing layer 37 is also provided between the third spraying pipe 351 and the third liquid collecting tank 352 in the third spraying area 35. As shown in Figures 5 and 6 , a packing layer 37 is also provided between the fourth spraying pipe 361 and the fourth liquid collecting tank 362 in the fourth spraying area 36.

[0075] In some embodiments, as shown in Figures 1-6 , the flue gas inlet 31 of the spray tower 3 is located at the bottom of the spray tower 3, and the flue gas outlet 32 ​​is located at the top of the spray tower 3. The flue gas flows from bottom to top within the spray tower 3, while the spray liquid is sprayed from top to bottom. This arrangement allows the flue gas and the spray liquid to flow in countercurrents, increasing their contact time and area, resulting in more efficient heat exchange and a better cooling effect of the spray liquid on the flue gas.

[0076] The operation process of the low-temperature flue gas treatment system of the embodiment of the present disclosure is described below using Example 2 as an example.

[0077] As shown in Figures 3 and 4, the high-temperature flue gas first flows through the primary side pipe 11 of the heat exchanger 1 and exchanges heat with the air in the secondary side pipe 12. After the heat exchange, the flue gas is cooled for the first time, while the temperature of the secondary side air increases. The flue gas after the first cooling enters the generator 21 of the absorption refrigeration machine 2 and provides heat to the generator 21 to evaporate the refrigerant therein. Then the flue gas flows out of the generator 21 and is cooled for the second time. The flue gas after the second cooling enters the spray tower 3 through the flue gas inlet 31 and exchanges heat with the spray liquid to achieve the third cooling. After the third cooling, the temperature of the flue gas reaches below room temperature and enters the adsorption tower 5. The adsorbent in the adsorption tower 5 adsorbs the flue gas below room temperature and removes the impurity gases therein. After adsorption, the flue gas becomes clean flue gas that can be directly discharged. After a period of use, the adsorbent can enter the regeneration tower 6. The hot air at the outlet of the secondary side pipeline 12 of the heat exchanger 1 can heat the adsorbent to achieve high-temperature decomposition and regeneration of the adsorbent. The regenerated adsorbent is sent back to the adsorption tower 5 for reuse.

[0078] In the spray tower 3, the temperature of the spray liquid increases after heat exchange with the flue gas. It then enters the cooling tower 4 to exchange heat with the air. After heat exchange, the temperature of the spray liquid decreases and is transported back to the spray tower 3 for further spraying. At the same time, the outlet 42 of the cooling tower 4 discharges the lower-temperature spray liquid. One branch of the low-temperature spray liquid flows to the electric refrigerator 7 and is used to dissipate heat from the electric refrigerator 7, while the other branch flows to the absorption refrigerator 2 and is used to dissipate heat from the absorber 24 and condenser 22.

[0079] In the description of the present disclosure, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise", "axial", "radial", "circumferential" and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present disclosure and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation to the present disclosure.

[0080] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features being referred to. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one such feature. Throughout the present disclosure, "plurality" means at least two, such as two, three, etc., unless otherwise specifically defined.

[0081] In this disclosure, unless otherwise expressly specified or limited, terms such as "mounted," "connected," "connect," and "fixed" should be understood in a broad sense. For example, they may refer to fixed connections, detachable connections, or integration; mechanical connections, electrical connections, or communication between them; direct connections or indirect connections through an intermediate medium; and internal communication between two elements or interaction between two elements, unless otherwise expressly limited. Those skilled in the art will understand the specific meanings of the above terms in this disclosure based on specific circumstances.

[0082] In the present disclosure, unless otherwise expressly specified or limited, when a first feature is "above" or "below" a second feature, it may mean that the first and second features are in direct contact, or the first and second features are in indirect contact through an intermediate medium. Furthermore, when a first feature is "above," "above," or "above" a second feature, it may mean that the first feature is directly above or diagonally above the second feature, or simply means that the first feature is at a higher level than the second feature. When a first feature is "below," "below," or "below" a second feature, it may mean that the first feature is directly below or diagonally below the second feature, or simply means that the first feature is at a lower level than the second feature.

[0083] In the present disclosure, the terms "one embodiment", "some embodiments", "examples", "specific examples", or "some examples" mean that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present disclosure. In this specification, the schematic expressions of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art can combine and combine different embodiments or examples described in this specification and features of different embodiments or examples without contradiction.

[0084] Although the above embodiments have been shown and described, it is understood that the above embodiments are illustrative and are not to be construed as limitations on the present disclosure. Changes, modifications, substitutions and variations of the above embodiments by those skilled in the art are all within the scope of protection of the present disclosure.

Claims

1. A low-temperature flue gas treatment system, comprising: A heat exchanger comprising a primary side pipeline and a secondary side pipeline, wherein the primary side pipeline has an inlet and an outlet for the flue gas to be purified, and the secondary side pipeline is used to pass a heat exchange medium, the heat exchange medium is used to exchange heat with the flue gas to reduce the temperature of the flue gas, and the flue gas after the primary cooling is discharged from the outlet of the primary side pipeline; An absorption refrigeration machine, the absorption refrigeration machine is connected to the outlet of the primary side pipeline, the absorption refrigeration machine is driven by the flue gas after the primary cooling and realizes secondary cooling of the flue gas after the primary cooling; A spray tower, the spray tower comprising a flue gas inlet, a first spray zone, a second spray zone, and a flue gas outlet, the absorption chiller being connected to the flue gas inlet, the flue gas after secondary cooling entering the spray tower through the flue gas inlet and sequentially flowing through the first spray zone and the second spray zone to be cooled to low-temperature flue gas below room temperature and discharged through the flue gas outlet, the absorption chiller being further connected to the second spray zone to cool the spray liquid in the second spray zone; a cooling tower connected to the first spraying area and configured to cool the spray liquid in the first spraying area; An adsorption tower, the adsorption tower is connected to the flue gas outlet of the spray tower, and an adsorbent is provided in the adsorption tower to adsorb and purify the low-temperature flue gas into clean flue gas; A regeneration tower is connected to the secondary side pipeline so that the heat exchange medium after heat exchange with the flue gas to be purified is used to heat and regenerate the adsorbent in the regeneration tower.

2. The low-temperature flue gas treatment system according to claim 1, wherein the first spray area is provided with a first spray pipe and a first collecting tank, the first spray pipe is used to spray spray liquid to spray cool the flue gas after secondary cooling, the first collecting tank is used to receive the spray liquid, the cooling tower includes a liquid inlet connected to the first collecting tank and a liquid outlet connected to the first spray pipe, the spray liquid in the first collecting tank is cooled by the cooling tower and then transported back to the first spray pipe.

3. The low-temperature flue gas treatment system according to claim 2, wherein the second spray area is provided with a second spray pipe and a second liquid collecting tank, the absorption refrigeration machine includes an evaporator, the second spray pipe and the second liquid collecting tank are both connected to the evaporator, and the spray liquid in the second liquid collecting tank is cooled by the evaporator and then transported back to the second spray pipe.

4. The low-temperature flue gas treatment system according to claim 3, wherein the absorption refrigerator comprises a generator, a condenser and an absorber, the generator is connected to the outlet of the primary side pipeline, the flue gas after primary cooling is used to provide heat to the generator to drive the absorption refrigerator, and the condenser and the absorber are both connected to the liquid outlet of the cooling tower to utilize the spray liquid discharged from the cooling tower to cool the refrigerant in the condenser and the absorber.

5. The low-temperature flue gas treatment system according to any one of claims 1 to 4, wherein the spray tower further comprises a third spray area, the third spray area being located between the first spray area and the second spray area, the flue gas after secondary cooling sequentially flows through the first spray area, the third spray area, and the second spray area, the third spray area being provided with a third spray pipe and a third liquid collecting tank, The low-temperature flue gas treatment system further includes an electric refrigerator connected to the third liquid collecting tank and the third spray pipe to cool the spray liquid in the third liquid collecting tank and transport the cooled spray liquid back to the third spray pipe. 6 . The low-temperature flue gas treatment system according to claim 5 , wherein the electric refrigerator is connected to the cooling tower, and the cooling tower is used to provide cooling water to the electric refrigerator to dissipate heat from the electric refrigerator.

7. The low-temperature flue gas treatment system according to any one of claims 1 to 6, wherein the spray tower further comprises a fourth spray area, the flue gas after secondary cooling flows through the fourth spray area, the first spray area and the second spray area in sequence, the fourth spray area is provided with a fourth spray pipe and a fourth liquid collecting tank, The low-temperature flue gas treatment system includes a circulation pipe connected between the fourth spray pipe and the fourth liquid collecting tank to circulate the spray liquid in the fourth spray area.

8. The low-temperature flue gas treatment system according to any one of claims 2 to 7, further comprising a liquid replenishing pipe, one end of which is connected to the liquid inlet of the cooling tower for replenishing spray liquid into the cooling tower.

9. The low-temperature flue gas treatment system according to claim 8, comprising a spray liquid treatment device, wherein the spray liquid treatment device is provided on the liquid replenishing pipe, and the spray liquid treatment device is used to adjust the pH value of the spray liquid flowing through the liquid replenishing pipe. 10 . The low-temperature flue gas treatment system according to claim 1 , wherein the spray tower comprises a packing layer, and the packing layer is arranged in the first spray zone and the second spray zone.

Images