System for treating flue gas

Abstract

The application discloses a system for treating flue gas, wherein the cooling liquid in the cooling tower is used to cool high-temperature flue gas and then is used to wash regenerated rich gas in the washing tower, so that additional cooling liquid is not added into the washing tower, and thus the amount of the cooling liquid used in the system for treating flue gas is reduced. The cooling liquid discharged from the washing tower is used to cool high-temperature flue gas through the first supplement inlet of the cooling tower, so that the amount of the cooling liquid used in the cooling tower is reduced, and thus the amount of the cooling liquid used in the system for treating flue gas is further reduced. After the cooling liquid discharged from the washing tower is used to cool high-temperature flue gas through the first supplement inlet of the cooling tower, the dissolved sulfur dioxide in the cooling liquid is released into the cooling tower, which is beneficial to the utilization of sulfur elements in the high-temperature flue gas, and thus the resource utilization rate of the high-temperature flue gas is improved. In addition, the system for treating flue gas can be operated in a self-sustaining mode, and thus the amount of the cooling liquid used is greatly reduced.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of flue gas treatment, in particular to a system for treating flue gas. BACKGROUND

[0002] Coal-fired flue gas contains a large amount of pollutants such as sulfur dioxide and nitrogen oxides. In order to reduce the harm to the human body, the coal-fired flue gas needs to be purified before being discharged into the atmosphere. In the related art, a low-temperature flue gas adsorption technology for integrated removal of pollutants is proposed. The low-temperature flue gas adsorption technology is as follows: first, the flue gas is cooled to low-temperature flue gas below room temperature, then the pollutants in the flue gas are adsorbed by the adsorbent, and finally the adsorbent saturated with adsorption is heated and regenerated for recycling.

[0003] However, a large amount of cooling liquid is needed to cool and wash the high-temperature flue gas in the low-temperature adsorption, and the amount of cooling liquid is large. Moreover, part of the sulfur dioxide in the high-temperature flue gas will dissolve in the cooling liquid in the process of cooling the high-temperature flue gas, which is not conducive to the utilization of sulfur elements in the high-temperature flue gas and reduces the resource utilization rate. SUMMARY

[0004] The present application aims to at least solve one of the technical problems in the related art to some extent. To this end, an embodiment of the present application proposes a system for treating flue gas, which can reduce the amount of cooling liquid and improve the resource utilization rate.

[0005] The system for treating flue gas of the embodiment of the present application comprises a cooling tower, an adsorption tower and a regeneration tower which are connected in sequence, the cooling tower is used for cooling high-temperature flue gas into low-temperature flue gas below zero degree, the cooling tower comprises a cooling liquid inlet, a cooling liquid outlet and a first supply inlet, cooling liquid flows into the cooling tower from the cooling liquid inlet to cool the high-temperature flue gas and flows out from the cooling liquid outlet, the adsorption tower has an adsorbent layer inside, the adsorbent layer is used for adsorbing and purifying the low-temperature flue gas entering the adsorption tower into clean flue gas, the adsorbent saturated with adsorption in the adsorption tower can be supplied into the regeneration tower to be regenerated and produce regenerated adsorbent and regeneration rich gas, the regenerated adsorbent can be supplied into the adsorption tower, the regeneration tower has a regeneration rich gas outlet for discharging the regeneration rich gas, the system for treating flue gas of the embodiment of the present application further comprises a sodium pyrosulfite system, the sodium pyrosulfite system comprises a washing tower and a sodium pyrosulfite synthesizing device, the washing tower comprises a gas inlet, a gas outlet, a washing inlet and a washing outlet, the gas inlet is communicated with the regeneration rich gas outlet, so that the regeneration rich gas discharged from the regeneration rich gas outlet enters the washing tower through the gas inlet to be washed to form washing gas and is discharged from the gas outlet, the gas outlet is connected with the sodium pyrosulfite synthesizing device, so that the washing gas discharged from the gas outlet enters the sodium pyrosulfite synthesizing device to prepare sodium pyrosulfite by the sodium pyrosulfite synthesizing device, the washing inlet is communicated with the cooling liquid outlet, so that the cooling liquid discharged from the cooling liquid outlet enters the washing tower through the washing inlet to wash the regeneration rich gas and is discharged from the washing outlet, the washing outlet is communicated with the first supply inlet, so that the cooling liquid discharged from the washing tower enters the cooling tower through the first supply inlet to supply the cooling liquid in the cooling tower.

[0006] The system for treating flue gas of the embodiment of the present application, the cooling liquid in the cooling tower is used to cool the high-temperature flue gas and then is used to wash the regenerated rich gas in the washing tower, so that additional cooling liquid is not added into the washing tower, thereby reducing the amount of cooling liquid used in the system for treating flue gas of the embodiment of the present application. The cooling liquid discharged from the washing tower is used to cool the high-temperature flue gas in the cooling tower through the first supply inlet, thereby reducing the amount of cooling liquid used in the cooling tower, and further reducing the amount of cooling liquid used in the system for treating flue gas of the embodiment of the present application. After the cooling liquid discharged from the washing tower is introduced into the cooling tower through the first supply inlet, the dissolved sulfur dioxide in the cooling liquid is released into the cooling tower, which is beneficial to the utilization of sulfur elements in the high-temperature flue gas, thereby improving the resource utilization rate of the high-temperature flue gas. In addition, in the system for treating flue gas of the embodiment of the present application, the cooling liquid discharged from the cooling tower can be used in the washing tower, and the cooling liquid discharged from the washing tower can be used in the cooling tower. Therefore, when there is a preset amount of cooling liquid in the system for treating flue gas of the embodiment of the present application, the cooling liquid requirements of the washing tower and the cooling tower can be met, and additional cooling liquid does not need to be supplemented into the system for treating flue gas of the embodiment of the present application in the subsequent operation process of the system for treating flue gas of the embodiment of the present application. That is, when there is a preset amount of cooling liquid in the system for treating flue gas of the embodiment of the present application, the system for treating flue gas of the embodiment of the present application can be self-sustaining, thereby greatly reducing the amount of cooling liquid used.

[0007] In some embodiments, the system for treating flue gas further comprises a cooling tower, which is in communication with the regenerated rich gas outlet to cool the regenerated rich gas and introduce the cooled rich gas into the gas inlet.

[0008] In some embodiments, the cooling tower comprises a cooling liquid inlet, a cooling liquid outlet and a second supply inlet, cooling liquid flows into the cooling tower from the cooling liquid inlet to cool the regenerated rich gas and flows out from the cooling liquid outlet, the cooling liquid outlet is in communication with the washing inlet, so that the cooling liquid discharged from the cooling liquid outlet enters the washing tower through the washing inlet to wash the regenerated rich gas together with the cooling liquid discharged from the cooling liquid outlet and is discharged from the washing outlet, the washing outlet is in communication with the second supply inlet, so that the liquid discharged from the washing tower enters the cooling tower through the second supply inlet to supply the cooling liquid in the cooling tower.

[0009] In some embodiments, the system for treating flue gas further comprises a liquid collecting device, the cooling liquid outlet and the cooling liquid outlet are both in communication with the liquid collecting device to store the cooling liquid discharged from the cooling tower and the cooling liquid discharged from the cooling tower in the liquid collecting device, the liquid collecting device is in communication with the washing inlet to supply the cooling liquid to the washing tower and / or supply the cooling liquid to the cooling tower to wash the regenerated rich gas in the washing tower.

[0010] In some embodiments, the washing tower comprises a first washing tower and a second washing tower connected in sequence, the first washing tower comprises the gas inlet and the washing inlet, and the second washing tower comprises the gas outlet and the washing outlet, so that the regenerated rich gas enters the first washing tower and the second washing tower in sequence for step-by-step washing.

[0011] In some embodiments, the system for treating flue gas further comprises a first liquid storage device in communication with the washing outlet to store the liquid discharged from the second washing tower, and the first make-up inlet and the second make-up inlet are both in communication with the first liquid storage device, so that the first liquid storage device supplies the cooling liquid to the cooling tower and / or supplies the cooling liquid to the cooling tower.

[0012] In some embodiments, the first washing tower further comprises an intermediate washing outlet for discharging the liquid in the first washing tower, the second washing tower further comprises an intermediate washing inlet for supplying the liquid into the second washing tower, and the system for treating flue gas further comprises a second liquid storage device in communication with the intermediate washing outlet to store the liquid discharged from the first washing tower, and the second washing inlet is in communication with the second liquid storage device, so that the second liquid storage device supplies the liquid for washing the regenerated rich gas into the second washing tower.

[0013] In some embodiments, the cooling tower comprises a first-stage cooling tower and a second-stage cooling tower connected in sequence, the first-stage cooling tower is in communication with the regenerated rich gas outlet, and the second-stage cooling tower is in communication with the gas inlet, so that the regenerated rich gas discharged from the regenerated rich gas outlet is subjected to first-stage cooling in the first-stage cooling tower and then subjected to second-stage cooling in the second-stage cooling tower, and the second-stage cooled regenerated rich gas is introduced into the washing tower for washing.

[0014] In some embodiments, the regeneration tower further comprises an upper carrier gas inlet arranged at the upper part of the regeneration tower and in communication with the flue gas outlet and / or the adsorption tower, so that a part of the low-temperature flue gas and / or a part of the adsorbed flue gas is introduced into the headspace of the regeneration tower as carrier gas through the upper carrier gas inlet, to reduce the temperature of the headspace of the regeneration tower and carry the regenerated rich gas generated in the regeneration tower to be discharged from the regenerated rich gas outlet, and / or the regeneration tower further comprises a lower carrier gas inlet arranged at the lower part of the regeneration tower and in communication with the adsorption tower, so that a part of the adsorbed flue gas discharged from the adsorption tower is introduced into the bottom space of the regeneration tower as lower carrier gas through the lower carrier gas inlet, to reduce the temperature of the bottom space of the regeneration tower, and to carry the regenerated rich gas generated in the regeneration tower to be discharged from the regenerated rich gas outlet together with the upper carrier gas.

[0015] In some embodiments, the system for treating flue gas further comprises a heat exchange device and a combustion furnace. The heat exchange device comprises a tail gas inlet, a tail gas outlet, a high-temperature flue gas inlet for passing in high-temperature flue gas, and a high-temperature flue gas outlet, wherein the tail gas inlet is in communication with the sodium sulfite synthesis device so that the tail gas discharged from the sodium metabisulfite enters the heat exchange device and cools the high-temperature flue gas, and the cooled high-temperature flue gas flows out from the high-temperature flue gas outlet, which is in communication with the flue gas inlet so that the cooled high-temperature flue gas enters the cooling tower, and the tail gas after heat exchange with the high-temperature flue gas can be discharged from the tail gas outlet; the combustion furnace is in communication with the tail gas outlet so that the heat-exchanged tail gas discharged from the heat exchange device enters the combustion furnace for loop reaction. BRIEF DESCRIPTION OF DRAWINGS

[0016] Figure 1 is a schematic diagram of a flue gas treatment system according to an embodiment of the present application.

[0017] Reference Signs:

[0018] 100, system for treating flue gas;

[0019] 1, cooling tower; 11, cooling liquid inlet; 12, cooling liquid outlet; 13, first supply inlet; 14, first flue gas inlet; 15, first flue gas outlet;

[0020] 2, adsorption tower; 21, adsorbent layer;

[0021] 3, regeneration tower; 31, regenerated rich gas outlet; 32, upper carrier gas inlet; 33, lower carrier gas inlet;

[0022] 4, sodium sulfite system; 41, scrubbing tower; 411, gas inlet; 412, gas outlet; 413, scrubbing inlet; 414, scrubbing outlet; 42, sodium sulfite synthesis device;

[0023] 415, first scrubbing tower; 4151, intermediate scrubbing outlet; 416, second scrubbing tower; 4161, intermediate scrubbing inlet;

[0024] 5, cooling tower; 51, cooling liquid inlet; 52, cooling liquid outlet; 53, second supply inlet; 54, second flue gas inlet; 55, second flue gas outlet;

[0025] 6, liquid collecting device;

[0026] 7, heat exchange device; 71, tail gas inlet; 72, tail gas outlet; 73, high-temperature flue gas inlet; 74, high-temperature flue gas outlet;

[0027] 8, combustion furnace;

[0028] 9, first liquid storage device;

[0029] 10. Second liquid storage device. Detailed Implementation

[0030] Embodiments of the present invention are described in detail below, examples of which are illustrated in the accompanying drawings. The embodiments described below with reference to the accompanying drawings are exemplary and intended to explain the present invention, and should not be construed as limiting the present invention.

[0031] The following describes a system 100 for treating flue gas according to an embodiment of the present invention with reference to the accompanying drawings.

[0032] like Figure 1 As shown, the flue gas treatment system 100 of this embodiment includes a cooling tower 1, an adsorption tower 2, and a regeneration tower 3 connected in sequence. The cooling tower 1 is used to cool high-temperature flue gas to low-temperature flue gas below zero degrees Celsius. The cooling tower 1 includes a coolant inlet 11, a coolant outlet 12, and a first replenishment inlet 13. Coolant flows into the cooling tower 1 from the coolant inlet 11 to cool the high-temperature flue gas and flows out from the coolant outlet 12. The adsorption tower 2 has an adsorbent layer 21, which is used to adsorb and purify the low-temperature flue gas entering the adsorption tower 2 into clean flue gas. The adsorbent in the adsorption tower 2 that is saturated with adsorption can be supplied to the regeneration tower 3 for regeneration to generate regenerated adsorbent and regenerated rich gas. The regenerated adsorbent can be supplied to the adsorption tower 2. The regeneration tower 3 has a regenerated rich gas outlet 31 for discharging the regenerated rich gas.

[0033] The flue gas treatment system 100 of this embodiment further includes a sodium pyrolysis system 4. The sodium pyrolysis system 4 includes a scrubbing tower 41 and a sodium pyrolysis synthesis device 42. The scrubbing tower 41 includes a gas inlet 411, a gas outlet 412, a scrubbing inlet 413, and a scrubbing outlet 414. The gas inlet 411 is connected to the regenerated rich gas outlet 31 so that the regenerated rich gas discharged from the regenerated rich gas outlet 31 enters the scrubbing tower 41 through the gas inlet 411 for scrubbing to form scrubbing gas, which is then discharged from the gas outlet 412. The gas outlet 412 is connected to the sodium pyrolysis synthesis device 42. The washing gas discharged from the gas outlet 412 enters the sodium pyrosulfite synthesis unit 42 so that the sodium pyrosulfite synthesis unit 42 can produce sodium metabisulfite. The washing inlet 413 is connected to the coolant outlet 12 so that the coolant discharged from the coolant outlet 12 enters the washing tower 41 through the washing inlet 413 to wash the regenerated rich gas and is discharged from the washing outlet 414. The washing outlet 414 is connected to the first supply inlet 13 so that the coolant discharged from the washing tower 41 is fed into the cooling tower 1 through the first supply inlet 13 to replenish the coolant in the cooling tower 1.

[0034] The high-temperature flue gas is cooled to low-temperature flue gas in the cooling tower 1, and the low-temperature flue gas is discharged from the cooling tower 1 and enters the adsorption tower 2. The adsorbent layer 21 in the adsorption tower 2 adsorbs and purifies the low-temperature flue gas entering the adsorption tower 2 into clean flue gas, and the clean flue gas meets the emission standard and can be directly discharged or discharged at a designated point. The adsorbent layer 21 saturated with adsorption in the adsorption tower 2 can be supplied to the regeneration tower 3 to regenerate the adsorbent and the regenerated gas. The adsorbent in the adsorbent layer 21 can be supplied to the adsorption tower 2 after regeneration to continue to adsorb and regenerate the low-temperature flue gas.

[0035] The low-temperature flue gas is adsorbed by the adsorption tower 2 to remove nitrogen oxides, sulfur dioxide and other harmful components in the low-temperature flue gas, thereby producing clean flue gas meeting the emission standard, and further realizing purification of the low-temperature flue gas. The adsorbent layer 21 saturated with adsorption enters the regeneration tower 3 for regeneration, so that the adsorbent layer 21 can continue to adsorb the low-temperature flue gas, thereby realizing cyclic utilization of the adsorbent layer 21, and further reducing the cost of purifying flue gas. Moreover, the adsorbent layer 21 saturated with adsorption enters the regeneration tower 3 to release nitrogen oxides, sulfur dioxide and other harmful components in the adsorbent layer 21 to form a regenerated gas, so as to facilitate treatment of nitrogen oxides, sulfur dioxide and other harmful components.

[0036] Since the solubility of nitrogen dioxide in nitrogen oxides is much greater than that of sulfur dioxide, the regeneration gas entering the washing tower 41 for washing can remove nitrogen dioxide in the regeneration gas to avoid the influence of nitrogen dioxide on the recovery of sulfur dioxide and improve the recovery rate of sulfur dioxide. In addition, other nitrogen oxides (such as nitric oxide, etc.) are dissolved in the cooling liquid, which further avoids affecting the recovery of sulfur dioxide and further improves the recovery rate of sulfur dioxide. The washing gas enters the sodium sulfite synthesis device 42 to synthesize sodium metabisulfite to realize resource utilization of sulfur dioxide.

[0037] The cooling liquid in the cooling tower 1 is cooled after cooling the high-temperature flue gas and enters the washing tower 41 to wash the regeneration gas, so as to avoid adding additional washing liquid to the washing tower 41, thereby reducing the amount of cooling liquid of the flue gas treatment system 100 of the embodiment of the present application. The cooling liquid discharged from the washing tower 41 enters the cooling tower 2 through the first supply inlet 13 to cool the high-temperature flue gas, thereby further reducing the amount of cooling liquid of the flue gas treatment system 100 of the embodiment of the present application.

[0038] After the cooling liquid discharged from the washing tower 41 enters the cooling tower 2 through the first supply inlet 13, the dissolved sulfur dioxide in the cooling liquid is released into the cooling tower 2, which is beneficial to the utilization of sulfur elements in the high-temperature flue gas, thereby improving the resource utilization rate of the high-temperature flue gas.

[0039] In addition, in the flue gas treatment system 100, the scrubbing tower 41 can use the cooling liquid discharged from the cooling tower 1, and the cooling tower 1 can use the cooling liquid discharged from the scrubbing tower 41. Therefore, when the flue gas treatment system 100 has a preset amount of cooling liquid, the cooling liquid requirements of the scrubbing tower 41 and the cooling tower 1 can be met. In the subsequent operation process of the flue gas treatment system 100, no additional cooling liquid needs to be supplemented to the flue gas treatment system 100. That is, when the flue gas treatment system 100 has a preset amount of cooling liquid, the flue gas treatment system 100 can be self-sustaining, thereby greatly reducing the amount of cooling liquid used.

[0040] It should be noted that the cooling liquid can be water or a solution suitable for cooling high-temperature flue gas and suitable for washing regenerated rich gas.

[0041] Optionally, the first supply inlet 13 is connected with a cooler, so that the cooling liquid entering the cooling tower 1 through the first supply inlet 13 is cooled by the cooler, so that the cooling liquid entering the cooling tower 1 through the first supply inlet 13 maintains a better temperature.

[0042] Preferably, the temperature of the low-temperature flue gas is -20°C to -10°C, so as to facilitate subsequent processing of the low-temperature flue gas.

[0043] In some specific embodiments, the first flue gas outlet 15 of the cooling tower 1 is in communication with the inlet of the adsorption tower 2, so that the low-temperature flue gas is discharged from the first flue gas outlet 15 and enters the adsorption tower 2 through the inlet of the adsorption tower 2.

[0044] The temperature of the regenerated rich gas discharged from the regeneration tower 3 is higher than the temperature of the low-temperature flue gas discharged from the cooling tower 1.

[0045] For example, the cooling liquid is water, and the flue gas treatment system 100 has a gas inlet amount of 5000 Nm 3 / h during operation, and can save 70 t to 90 t of water per hour.

[0046] For another example, the cooling liquid is water, and the flue gas treatment system 100 has a gas inlet amount of 7000 Nm 3 / h during operation, and can save 80 t to 95 t of water per hour.

[0047] To this end, in some embodiments, as shown in Figure 1 the flue gas treatment system 100 further comprises a cooling tower 5, which is in communication with the regenerated rich gas outlet 31 to cool the regenerated rich gas and pass the cooled rich gas into the gas inlet 411.

[0048] The regenerated rich gas is cooled by the cooling tower 5 to bring it to a suitable temperature range, so that the pyrosodium system 4 can recover sulfur from the regenerated rich gas, thereby improving the resource utilization rate of sulfur from the regenerated rich gas by the pyrosodium system 4.

[0049] In some specific embodiments, the regenerated rich gas outlet 31 is connected to the second flue gas inlet 54 of the cooling tower 5 so that the regenerated rich gas can be discharged from the regenerated tower 3 through the regenerated rich gas outlet 31 and enter the cooling tower 5 through the second flue gas inlet 54 for cooling.

[0050] Furthermore, the second flue gas outlet 55 of the cooling tower 5 is connected to the gas outlet 411 so that the cooled rich gas can leave the cooling tower 5 through the second flue gas outlet 55 and enter the scrubbing tower 41 through the gas outlet 411.

[0051] like Figure 1 As shown, in some embodiments, the cooling tower 5 includes a cooling liquid inlet 51, a cooling liquid outlet 52, and a second replenishment inlet 53. The cooling liquid flows into the cooling tower 5 from the cooling liquid inlet 51 to cool the regenerated rich gas and flows out from the cooling liquid outlet 52. The cooling liquid outlet 52 is connected to the scrubbing inlet 413 so that the cooling liquid discharged from the cooling liquid outlet 52 enters the scrubbing tower 41 through the scrubbing inlet 413 and, together with the cooling liquid discharged from the cooling liquid outlet 12, scrubs the regenerated rich gas and discharges from the scrubbing outlet 414. The scrubbing outlet 414 is connected to the second replenishment inlet 53 so that the liquid discharged from the scrubbing tower 41 enters the cooling tower 5 through the second replenishment inlet 53 to replenish the cooling liquid in the cooling tower 5.

[0052] It should be noted that the cooling fluid can be water, or a solution suitable for cooling high-temperature flue gas or for scrubbing regenerated rich gas. The cooling fluid can be the same liquid as the coolant, or it can be different from the coolant.

[0053] The liquid discharged from the scrubbing tower 41 enters the cooling tower 5 through the second replenishment inlet 53, thereby reducing the amount of cooling liquid used, and thus reducing the amount of cooling liquid used in the flue gas treatment system 100 of this embodiment of the invention.

[0054] The cooling liquid discharged from the cooling tower 5 enters the scrubbing tower 41 to scrub the regenerated rich gas, so as to further avoid adding additional scrubbing liquid to the scrubbing tower 41.

[0055] In addition, the liquid discharged from the scrubbing tower 41 is fed into the cooling tower 5 through the second replenishment inlet 53, which allows the sulfur dioxide in the liquid to be released into the regenerated rich gas in the form of gas, which is conducive to the utilization of sulfur elements and thus further improves the resource utilization rate of high temperature flue gas.

[0056] like Figure 1As shown, optionally, the cooling liquid and the cooling down liquid are the same liquid, and the cooling liquid outlet 12 is in communication with the second supply inlet 53, so that the discharged cooling liquid in the cooling tower 1 can directly enter the cooling down tower 5 as the cooling down liquid in the cooling down tower 5, thereby enabling the cooling down tower 5 to directly obtain supply from the cooling tower 1, and further enabling the cooling down liquid in the cooling down tower 5 to be replenished more quickly by the cooling tower 1.

[0057] As shown, further, the cooling liquid and the cooling down liquid are the same liquid, and the cooling down liquid outlet 52 is in communication with the first supply inlet 13, so that the discharged cooling down liquid in the cooling down tower 5 can directly enter the cooling tower 1 as the cooling liquid in the cooling tower 1, thereby enabling the cooling tower 1 to directly obtain supply from the cooling down tower 5, and further enabling the cooling liquid in the cooling tower 1 to be replenished more quickly by the cooling down tower 5. Figure 1

[0058] Optionally, the cooling down liquid discharged from the cooling down liquid outlet 52 is mixed with the cooling liquid discharged from the cooling liquid outlet 12 before entering the washing tower 41 to wash the regenerated rich gas.

[0059] Optionally, the second supply inlet 53 is connected with a cooler, so that the cooling down liquid entering the cooling down tower 5 through the second supply inlet 53 is cooled by the cooler, thereby keeping the cooling down liquid entering the cooling down tower 5 through the second supply inlet 53 at a better temperature.

[0060] As shown, in some embodiments, the system 100 for treating flue gas further comprises a liquid collecting device 6, and the cooling liquid outlet 12 and the cooling down liquid outlet 52 are both in communication with the liquid collecting device 6, so that the cooling liquid discharged from the cooling tower 1 and the cooling down liquid discharged from the cooling down tower 5 are stored in the liquid collecting device 6, and the liquid collecting device 6 is in communication with the washing inlet 413, so that the liquid collecting device 6 supplies the cooling liquid to the washing tower 41 and / or supplies the cooling down liquid to the cooling down tower 5 to wash the regenerated rich gas in the washing tower 41. Figure 1 The liquid collecting device 6 can store the cooling liquid and the cooling down liquid, so as to supply the washing tower 41 according to the actual needs of the washing tower 41.

[0061] The high-temperature flue gas and the regenerated rich gas contain solid particles such as coal powder, and when the high-temperature flue gas is cooled, the cooling liquid can wash the solid particles in the high-temperature flue gas into the cooling liquid, and when the regenerated rich gas is cooled, the cooling down liquid can wash the solid particles in the regenerated rich gas into the cooling down liquid, thereby causing the cooling liquid discharged from the cooling tower 1 and the cooling down liquid discharged from the cooling down tower 5 to contain solid particles.

[0062]

[0063] ​​The cooling liquid discharged from the cooling tower 1 and the cooling liquid discharged from the cooling tower 5 will be deposited in the collecting device 6, and the solid particles in the cooling liquid and the cooling liquid are removed by the collecting device 6 to improve the cleaning effect of the cooling liquid and the cooling liquid on the regenerated rich gas in the washing tower 41.

[0064] Optionally, the system 100 for treating flue gas comprises a plurality of pumps, so that the cooling liquid discharged from the cooling tower 1 and the cooling liquid discharged from the cooling tower 5 can be pumped into the collecting device 6 by the pumps, and the collecting device 6 can supply the cooling liquid into the washing tower 41 and / or supply the cooling liquid into the cooling tower 5 by the pumps, so as to improve the flow stability of the cooling liquid and the cooling liquid in the system 100 for treating flue gas in the embodiments of the present application by the pumps.

[0065] As shown in Figure 1 In some embodiments, the washing tower 41 comprises a first washing tower 415 and a second washing tower 416 which are sequentially communicated, the first washing tower 415 comprises a gas inlet 411 and a washing inlet 413, and the second washing tower 416 comprises a gas outlet 412 and a washing outlet 414, so that the regenerated rich gas sequentially enters the first washing tower 415 and the second washing tower 416 for step-by-step washing.

[0066] The first washing tower 415 performs primary washing on the regenerated rich gas, and the second washing tower 416 performs secondary washing on the regenerated rich gas, so that the first washing tower 415 and the second washing tower 416 can better wash the nitrogen dioxide and other nitrogen oxides in the regenerated rich gas, and the first washing tower 415 and the second washing tower 416 can also wash the solid particles in the regenerated rich gas, thereby facilitating the preparation of sodium pyrosulfite with higher purity from the regenerated rich gas.

[0067] As shown in Figure 1 Optionally, the cooling liquid discharged from the cooling tower 1 and the cooling liquid discharged from the cooling tower 5 are mixed into a mixed liquid, and then the mixed liquid enters the first washing tower 415 to wash the regenerated rich gas, and after the first washing tower 415 completes the primary washing, the mixed liquid enters the second washing tower 416 to perform secondary washing on the regenerated rich gas by the mixed liquid.

[0068] As shown in Figure 1 In some embodiments, the system 100 for treating flue gas further comprises a first liquid storage device 9, the first liquid storage device 9 is in communication with the washing outlet 414 to store the liquid discharged from the second washing tower 416, and the first replenishing inlet 13 and the second replenishing inlet 53 are both in communication with the first liquid storage device 9, so that the first liquid storage device 9 replenishes the cooling liquid into the cooling tower 1 and / or replenishes the cooling liquid into the cooling tower 5.

[0069] The first liquid storage device 9 can store coolant and cooling liquid, so as to further facilitate the adjustment of the flow rate of coolant supplied to cooling tower 1 according to the actual operation of cooling tower 1, and further facilitate the adjustment of the flow rate of cooling liquid supplied to cooling tower 5 according to the actual operation of cooling tower 5, thereby enabling cooling tower 1 and cooling tower 5 to operate more stably.

[0070] Solid particles in the coolant and cooling liquid discharged from the second scrubbing tower 416 are deposited in the first liquid storage device 9. This allows the first liquid storage device 9 to remove solid particles from the coolant and cooling liquid discharged from the second scrubbing tower 416, thereby reducing the amount of impurities in the coolant supplied to the cooling tower 1 from the first liquid storage device 9 and reducing the amount of cooling liquid supplied to the cooling tower 5 from the first liquid storage device 9.

[0071] like Figure 1 As shown, in some embodiments, the first scrubbing tower 415 further includes an intermediate scrubbing outlet 4151 for discharging liquid from the first scrubbing tower 415, and the second scrubbing tower 416 further includes an intermediate scrubbing inlet 4161 for supplying liquid into the second scrubbing tower 416. The flue gas treatment system 100 further includes a second liquid storage device 10, which is connected to the intermediate scrubbing outlet 4151 to store liquid discharged from the first scrubbing tower 415. The second scrubbing inlet 413 is connected to the second liquid storage device 10 so that the second liquid storage device 10 supplies liquid for scrubbing the regenerated rich gas into the second scrubbing tower 416.

[0072] The second liquid storage device 10 can store the mixed liquid discharged from the first washing tower 415 in order to control and regulate the flow rate of the mixed liquid entering the second washing tower 416.

[0073] Solid particles in the coolant and cooling liquid discharged from the first scrubbing tower 415 are deposited in the second liquid storage device 10, so as to remove solid particles in the coolant and cooling liquid discharged from the first scrubbing tower 415 through the second liquid storage device 10, thereby increasing the cleaning effect of the second scrubbing tower 416.

[0074] In some embodiments, the cooling tower 5 includes a first-stage cooling tower and a second-stage cooling tower connected in sequence. The first-stage cooling tower 5 is connected to the regenerated rich gas outlet 31, and the second-stage cooling tower is connected to the gas inlet 411, so that the regenerated rich gas discharged from the regenerated rich gas outlet 31 is cooled by the first-stage cooling tower and then enters the second-stage cooling tower for secondary cooling. The regenerated rich gas after secondary cooling is then fed into the scrubbing tower 41 for scrubbing.

[0075] The regenerated rich gas is cooled stepwise by using a first-stage cooling tower and a second-stage cooling tower to enhance the cooling effect. Furthermore, by using a first-stage and a second-stage cooling tower, the footprint of a single cooling tower 5 can be reduced, thus preventing the single cooling tower 5 from becoming too large.

[0076] In related technologies, during the adsorbent desorption and regeneration process in the regeneration tower, a large amount of nitrogen gas needs to be introduced into the regeneration tower to carry the rich regeneration gas out of the regeneration tower. Because nitrogen gas needs to be introduced as a carrier gas, the investment and operating costs are high.

[0077] Therefore, such as Figure 1 As shown, in some embodiments, the regeneration tower 3 further includes an upper carrier gas inlet 32, which is located at the top of the regeneration tower 3 and communicates with the flue gas outlet and / or the adsorption tower 2, so that a portion of the low-temperature flue gas and / or a portion of the adsorbed flue gas are introduced into the top space of the regeneration tower 3 as carrier gas through the upper carrier gas inlet 32, so as to reduce the temperature of the top space of the regeneration tower 3 and carry the regeneration rich gas generated in the regeneration tower 3 out from the regeneration rich gas outlet 31.

[0078] In an embodiment of the present invention, a portion of low-temperature flue gas is introduced into the top space of the regeneration tower 3 as a carrier gas. This can conveniently control the temperature at the top of the regeneration tower 3, and avoid the generation of water vapor and condensate at the top of the regeneration tower 3 due to the temperature rise of the preheating section and regeneration section of the regeneration tower 3. This can solve problems such as material blockage at the top of the regeneration tower 3, blockage of the adsorbent channel, and false alarms of the material level at the top of the regeneration tower 3 caused by the mixing of condensate and adsorbent dust.

[0079] On the other hand, the low-temperature flue gas plays the same role as inert gases such as nitrogen. Therefore, nitrogen can be used as a carrier gas or at least the amount of nitrogen used can be reduced. The regeneration rich gas can be quickly discharged from the regeneration tower 3, while the water vapor generated in the regeneration tower 3 due to the heating of the adsorbent can also be discharged. The oxygen concentration in the regeneration tower 3 can also be reduced, thereby reducing the risk of combustion of the adsorbent in the regeneration tower 3.

[0080] On the other hand, by avoiding the generation of large amounts of water vapor and condensate in the regeneration tower and by quickly removing small amounts of water vapor and condensate from the regeneration tower, corrosion of the regeneration tower is avoided or at least mitigated.

[0081] like Figure 1 As shown, in some embodiments, the regeneration tower 3 further includes a downgassing inlet 33, which is located at the bottom of the regeneration tower 3 and communicates with the adsorption tower 2. This allows a portion of the adsorbed flue gas discharged from the adsorption tower 2 to be used as downgassing gas and introduced into the bottom space of the regeneration tower 3 through the downgassing inlet 33 to reduce the temperature of the bottom space of the regeneration tower 3. The downgassing gas, together with the upgassing gas, carries the regeneration rich gas generated in the regeneration tower 3 and is discharged from the regeneration rich gas outlet 31.

[0082] In the embodiments of the present application, by introducing the up-carrier gas and the down-carrier gas as the carrier gas through the two carrier gas inlets of the regeneration tower 3, the regenerated rich gas in the regeneration tower 3 can be completely discharged. The down-carrier gas introduced into the bottom of the regeneration tower 3 is more beneficial to the cooling of the cooling section of the regeneration tower.

[0083] Further, by taking part of the clean flue gas discharged from the adsorption tower 2 as the down-carrier gas, the clean flue gas is reused, and the cost is reduced. Moreover, the clean flue gas does not pollute the adsorbent in the cooling section of the regeneration tower 3.

[0084] It should be noted that the adsorbent reaching the cooling section of the regeneration tower 3 is the desorbed adsorbent, and the clean flue gas introduced into the cooling section can prevent the adsorbent from being polluted. The low-temperature flue gas after being sprayed and cooled is not adsorbed and purified by the adsorption tower 2, and therefore the low-temperature flue gas discharged from the cooling tower 1 cannot be introduced into the cooling section.

[0085] In some embodiments, the down-carrier gas inlet 33 is arranged on the side wall of the lower part of the regeneration tower 3, the adsorbent outlet of the regeneration tower 3 is connected with the adsorbent feeding port of the adsorption tower 2, and the adsorbent outlet is arranged on the bottom wall of the regeneration tower 3.

[0086] As shown in FIG. 1, Figure 1 In some embodiments, the system 100 for treating flue gas further comprises a heat exchange device 7 and a combustion furnace 8. The heat exchange device 7 comprises a tail gas inlet 71, a tail gas outlet 72, a high-temperature flue gas inlet 73 and a high-temperature flue gas outlet 74. The high-temperature flue gas inlet 73 is used for introducing high-temperature flue gas. The tail gas inlet 71 is communicated with the sodium sulfite synthesis device 42 so that the tail gas discharged from the sodium sulfite flows into the heat exchange device 7, the high-temperature flue gas is cooled, and the cooled high-temperature flue gas flows out from the high-temperature flue gas outlet 74. The high-temperature flue gas outlet 74 is communicated with the flue gas inlet so that the cooled high-temperature flue gas enters the cooling tower 1. The tail gas after heat exchange with the high-temperature flue gas can be discharged from the tail gas outlet 72. The combustion furnace 8 is communicated with the tail gas outlet 72 so that the heat-exchanged tail gas discharged from the heat exchange device 7 enters the combustion furnace 8 to perform a loop reaction, so as to treat the tail gas by the combustion furnace 8.

[0087] The temperature of the tail gas discharged from the sodium sulfite synthesis device 42 is low. By the heat exchange device 7, the tail gas and the high-temperature flue gas are heat-exchanged, the temperature of the high-temperature flue gas is reduced, the cooling capacity loss of the cooling tower 1 for cooling the high-temperature flue gas is reduced, and the energy consumption of the system 100 for treating flue gas in the embodiments of the present application is reduced.

[0088] By the heat exchange device 7, the tail gas and the high-temperature flue gas are heat-exchanged, the temperature of the tail gas is increased, and the heat loss of the combustion furnace 8 after the tail gas enters the combustion furnace 8 is reduced.

[0089] In the description of the present application, it is to be understood that the orientations or positional relationships indicated by the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "upper", "lower", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", "axial", "radial", "circumferential" and the like are based on the orientations or positional relationships shown in the drawings, and are only for the purpose of facilitating the description of the present application and simplifying the description, and do not indicate or imply that the devices or elements indicated thereby must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as limiting the present application.

[0090] In addition, the terms "first", "second", "third", etc. are only used for descriptive purposes and cannot be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated thereby. Therefore, the features defined with "first", "second", etc. can explicitly or implicitly include at least one of the features. In the description of the present application, the meaning of "a plurality of" is at least two, such as two, three, etc., unless otherwise explicitly specified and limited.

[0091] In the present application, unless otherwise explicitly specified and limited, the terms "mounting", "connecting", "connecting", "fixing" and the like should be understood broadly, for example, it can be fixedly connected, or it can be detachably connected, or it can be integrated; it can be mechanically connected, or it can be electrically connected or in communication with each other; it can be directly connected, or it can be indirectly connected through an intermediate medium; it can be the internal communication or interaction relationship of two elements, unless otherwise explicitly limited. For those skilled in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.

[0092] In the present application, unless otherwise explicitly specified and limited, the first feature is "on" or "under" the second feature, which can be direct contact between the first and second features, or indirect contact between the first and second features through an intermediate medium. Moreover, the first feature "above", "above" and "above" the second feature can be directly above or obliquely above the first feature, or only indicate that the horizontal height of the first feature is higher than that of the second feature. The first feature "below", "below" and "below" the second feature can be directly below or obliquely below the first feature, or only indicate that the horizontal height of the first feature is less than that of the second feature.

[0093] In this disclosure, the terms "one embodiment", "some embodiments", "an example", "a specific example", or "some examples" mean that a particular feature, structure, material, or characteristic is included in at least one embodiment or example of the present disclosure. The illustrative appearances of the above-mentioned terms in various places in the specification are not necessarily referred to the same embodiment or example. Moreover, the particular features, structures, materials, or characteristics can be combined in any suitable manner in one or more embodiments or examples. Furthermore, the terms "comprising", "containing", "having" or "including" and their derivatives, mean "including but not limited to". The terms "coupled" and "connected", along with their derivatives, mean "directly or indirectly connected".

[0094] Although the above-mentioned embodiments have been shown and described, it is to be understood that the above-mentioned embodiments are exemplary, and are not to be construed as limiting the present disclosure, and the changes, modifications, replacements and variations made by those skilled in the art to the above-mentioned embodiments are within the protection scope of the present disclosure.

Claims

1. A system for treating flue gas, characterized in that, The system comprises a cooling tower, an adsorption tower, and a regeneration tower connected in sequence. The cooling tower cools high-temperature flue gas to below-zero temperature. The cooling tower includes a coolant inlet, a coolant outlet, and a first replenishment inlet. Coolant flows into the cooling tower from the coolant inlet to cool the high-temperature flue gas and flows out from the coolant outlet. The adsorption tower has an adsorbent layer that adsorbs and purifies the low-temperature flue gas entering the adsorption tower into clean flue gas. The adsorbent in the adsorption tower that is saturated is supplied to the regeneration tower for regeneration, producing regenerated adsorbent and regenerated rich gas. The regenerated adsorbent is supplied to the adsorption tower. The regeneration tower has a regenerated rich gas outlet for discharging the regenerated rich gas. The flue gas treatment system further includes a sodium pyrosulfite system, which includes a scrubbing tower and a sodium pyrosulfite synthesis unit. The scrubbing tower includes a gas inlet, a gas outlet, a scrubbing inlet, and a scrubbing outlet. The gas inlet is connected to the regenerated rich gas outlet so that the regenerated rich gas discharged from the regenerated rich gas outlet enters the scrubbing tower through the gas inlet to be scrubbed to form scrubbing gas, which is then discharged from the gas outlet. The gas outlet is connected to the sodium pyrosulfite synthesis unit so that the scrubbing gas discharged from the gas outlet enters the sodium pyrosulfite synthesis unit to produce sodium metabisulfite. The scrubbing inlet is connected to the coolant outlet so that the coolant discharged from the coolant outlet enters the scrubbing tower through the scrubbing inlet to scrub the regenerated rich gas, which is then discharged from the scrubbing outlet. The scrubbing outlet is connected to the first replenishment inlet so that the coolant discharged from the scrubbing tower enters the cooling tower through the first replenishment inlet to replenish the coolant in the cooling tower. It also includes a cooling tower, which is connected to the regenerated rich gas outlet to cool the regenerated rich gas and introduce the cooled rich gas into the gas inlet; The cooling tower includes a cooling liquid inlet, a cooling liquid outlet, and a second replenishment inlet. Cooling liquid flows into the cooling tower from the cooling liquid inlet to cool the regenerated rich gas and flows out from the cooling liquid outlet. The cooling liquid outlet is connected to the washing inlet so that the cooling liquid discharged from the cooling liquid outlet enters the washing tower through the washing inlet and, together with the cooling liquid discharged from the cooling liquid outlet, washes the regenerated rich gas and then discharges from the washing outlet. The washing outlet is connected to the second replenishment inlet so that the liquid discharged from the washing tower enters the cooling tower through the second replenishment inlet to replenish the cooling liquid in the cooling tower.

2. The system for treating flue gas according to claim 1, characterized in that, It also includes a liquid collection device, wherein the coolant outlet and the cooling liquid outlet are both connected to the liquid collection device so that the coolant discharged from the cooling tower and the cooling liquid discharged from the cooling tower are stored in the liquid collection device. The liquid collection device is connected to the washing inlet so that the liquid collection device supplies the coolant and the cooling liquid to the washing tower to wash the regenerated rich gas in the washing tower.

3. The system for treating flue gas according to claim 2, characterized in that, The scrubbing tower includes a first scrubbing tower and a second scrubbing tower connected in sequence. The first scrubbing tower includes the gas inlet and the scrubbing inlet, and the second scrubbing tower includes the gas outlet and the scrubbing outlet, so that the regenerated rich gas enters the first scrubbing tower and the second scrubbing tower in sequence for staged scrubbing.

4. The system for treating flue gas according to claim 3, characterized in that, It also includes a first liquid storage device, which is connected to the washing outlet to store liquid discharged from the second washing tower. The first supply inlet and the second supply inlet are both connected to the first liquid storage device so that the first liquid storage device can supply coolant to the cooling tower and / or supply cooling liquid to the cooling tower.

5. The system for treating flue gas according to claim 4, characterized in that, The first washing tower further includes an intermediate washing outlet for discharging liquid from the first washing tower, and the second washing tower further includes an intermediate washing inlet for supplying liquid into the second washing tower. The flue gas treatment system further includes a second liquid storage device, which is connected to the intermediate scrubbing outlet to store liquid discharged from the first scrubbing tower. The intermediate scrubbing inlet is connected to the second liquid storage device so that the second liquid storage device supplies liquid to the second scrubbing tower for scrubbing the regenerated rich gas.

6. The system for treating flue gas according to claim 1, characterized in that, The cooling tower includes a first-stage cooling tower and a second-stage cooling tower connected in sequence. The first-stage cooling tower is connected to the regenerated rich gas outlet, and the second-stage cooling tower is connected to the gas inlet, so that the regenerated rich gas discharged from the regenerated rich gas outlet undergoes primary cooling in the first-stage cooling tower and then enters the second-stage cooling tower for secondary cooling. The regenerated rich gas after secondary cooling is then introduced into the washing tower for washing.

7. The system for treating flue gas according to any one of claims 1-6, characterized in that, The regeneration tower also includes an upper carrier gas inlet, which is located at the top of the regeneration tower and communicates with the flue gas outlet of the cooling tower and / or the adsorption tower. This allows a portion of the low-temperature flue gas and / or a portion of the adsorbed flue gas to be introduced as upper carrier gas into the top space of the regeneration tower through the upper carrier gas inlet. This serves to lower the temperature of the top space of the regeneration tower and carries the regeneration-rich gas generated within the regeneration tower out through the regeneration-rich gas outlet. The regeneration tower also includes a downgassing inlet, which is located at the bottom of the regeneration tower and communicates with the adsorption tower. This allows a portion of the adsorbed flue gas discharged from the adsorption tower to be used as downgassing gas and introduced into the bottom space of the regeneration tower through the downgassing inlet. This is done to reduce the temperature of the bottom space of the regeneration tower and, together with the upgassing gas, carries the regeneration rich gas generated in the regeneration tower out through the regeneration rich gas outlet.

8. The system for treating flue gas according to any one of claims 1-6, characterized in that, Also includes: A heat exchange device includes an exhaust gas inlet, an exhaust gas outlet, a high-temperature flue gas inlet, and a high-temperature flue gas outlet. The high-temperature flue gas inlet is used to introduce high-temperature flue gas. The exhaust gas inlet is connected to the sodium metabisulfite synthesis device so that the exhaust gas discharged from the sodium metabisulfite enters the heat exchange device to cool the high-temperature flue gas and flows out from the high-temperature flue gas outlet. The high-temperature flue gas outlet is connected to the flue gas inlet of the cooling tower so that the cooled high-temperature flue gas enters the cooling tower, and the exhaust gas after heat exchange with the high-temperature flue gas is discharged from the exhaust gas outlet. A combustion furnace is connected to the exhaust gas outlet so that the heat-exchanged exhaust gas discharged from the heat exchange device enters the combustion furnace for a loop reaction.

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