Low temperature flue gas treatment system

Abstract

The present application relates to the field of adsorption purification technology and discloses a low-temperature flue gas treatment system, which comprises a heat exchanger, an absorption refrigerating machine, a spray tower, a cooling tower, an adsorption tower and a regeneration tower. The flue gas is cooled once by the heat exchanger, and then the flue gas drives the absorption refrigerating machine to work and is cooled twice. The flue gas is cooled to below room temperature after heat exchange with the spray liquid in the spray tower. Then the flue gas is purified into clean flue gas by the adsorption tower. The heat exchange medium after heat exchange with the flue gas is used for the regeneration tower to regenerate the adsorbent. The flue gas is first cooled by the heat exchanger and the absorption refrigerating machine to recover waste heat and reduce the temperature, and then enters the spray tower, which is beneficial to reducing the cooling load of the spray tower and reducing energy consumption. The flue gas is cooled in stages in the spray tower, which can improve the flue gas cooling effect. At the same time, the waste heat recovered by the heat exchanger is used for the regeneration tower, which improves the economy of the whole system.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of adsorption purification, and particularly relates to a low-temperature flue gas treatment system. BACKGROUND

[0002] The flue gas generated by a boiler contains various pollutants, and the pollutants need to be removed before the flue gas is discharged. For the nitrogen compounds in the flue gas, an adsorbent is generally used for adsorption removal. Since the adsorption process needs to be carried out at low temperature, the flue gas needs to be cooled to a low temperature first, and then the flue gas is introduced into the adsorbent for adsorption treatment. The adsorbent needs to be regenerated after being used for a period of time, and the regeneration process needs to meet the high-temperature condition.

[0003] In the related art, the cooling of the flue gas and the high-temperature regeneration of the adsorbent need to use high-power refrigeration and heating equipment respectively. In particular, in the last stage of the flue gas cooling, the temperature of the flue gas is low, which results in a low energy efficiency of the refrigeration equipment and a large energy consumption, and seriously affects the economy of the flue gas treatment process. SUMMARY

[0004] The present application is made based on the discovery and understanding of the inventors on the following facts and problems:

[0005] The flue gas generated in the boiler has a high temperature, and the flue gas temperature will decrease during the flue gas discharge process, resulting in a large waste of waste heat. Moreover, a large amount of heat is needed in the regeneration process of the adsorbent in the regeneration tower to heat and regenerate the adsorbent. Therefore, the inventors consider that the waste heat of the flue gas should be fully utilized to reduce the waste of energy and improve the economy of the flue gas treatment process.

[0006] The present application aims to at least solve one of the technical problems in the related art. To this end, the present application provides a low-temperature flue gas treatment system.

[0007] The low-temperature flue gas treatment system of the present application comprises a heat exchanger, an absorption refrigerator, a spray tower, a cooling tower, an adsorption tower and a regeneration tower, the heat exchanger comprises a primary side pipeline and a secondary side pipeline, the primary side pipeline has an inlet for the flue gas to be purified and an outlet, the secondary side pipeline is used for passing a heat exchange medium, the heat exchange medium is used for heat exchange with the flue gas to reduce the temperature of the flue gas once, and the flue gas after the temperature reduction once is discharged from the outlet of the primary side pipeline; the absorption refrigerator is connected with the outlet of the primary side pipeline, the absorption refrigerator is driven by the flue gas after the temperature reduction once and realizes the temperature reduction twice of the flue gas after the temperature reduction once; the spray tower comprises a flue gas inlet, a first spray zone, a second spray zone and a flue gas outlet, the absorption refrigerator is connected with the flue gas inlet, the flue gas after the temperature reduction twice enters the spray tower through the flue gas inlet and flows through the first spray zone and the second spray zone in sequence to be cooled to low-temperature flue gas below room temperature and is discharged through the flue gas outlet, and the absorption refrigerator is also connected with the second spray zone to cool the spray liquid in the second spray zone; the cooling tower is connected with the first spray zone to cool the spray liquid in the first spray zone; the adsorption tower is connected with the flue gas outlet of the spray tower, and an adsorbent is arranged in the adsorption tower to adsorb and purify the low-temperature flue gas into clean flue gas; and the regeneration tower is connected with the secondary side pipeline, 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 to regenerate the adsorbent.

[0008] In the low-temperature flue gas treatment system of the present application, the flue gas to be purified is first reduced in temperature once by the heat exchanger to recover part of the waste heat and then is reduced in temperature twice by the absorption refrigerator to further recover the waste heat and reduce the temperature, so that the flue gas to be purified enters the spray tower after the temperature reduction twice, thereby reducing the cooling load of the spray tower and being beneficial to reducing the energy consumption of the spray tower.

[0009] The flue gas after the temperature reduction twice enters the spray tower and is first sprayed and cooled in the first spray zone and then is further sprayed and cooled in the second spray zone, and the spray liquid in the second spray zone can be cooled by the cold energy prepared by the absorption refrigerator, so that the flue gas cooling effect can be improved by the staged cooling and the cold energy of the absorption refrigerator, and the energy utilization rate is improved. The flue gas after the temperature reduction twice is sprayed and cooled by the spray tower to be low-temperature flue gas below room temperature, and the low-temperature flue gas has a high adsorption rate in the adsorption tower, so that a good purification effect can be achieved. In addition, the waste heat recovered by the heat exchanger can be used for heating in the regeneration tower to regenerate the adsorbent, so that the waste heat is reused and the economy of the whole system is improved.

[0010] Optionally, the first spray area is provided with a first spray pipe and a first liquid collecting tank, the first spray pipe is used for spraying the spray liquid to spray cool the flue gas after the first temperature reduction, and the first liquid collecting tank is used for receiving the spray liquid, the cooling tower comprises a liquid inlet communicated with the first liquid collecting tank and a liquid outlet communicated with the first spray pipe, and the spray liquid in the first liquid collecting tank is conveyed back to the first spray pipe after being cooled by the cooling tower.

[0011] In the low-temperature flue gas treatment system, the first spray pipe can uniformly spray the spray liquid in the first spray area, the spray liquid can be more fully contacted with the flue gas, and the flue gas has a better heat exchange effect. After the heat exchange between the spray liquid and the flue gas, the temperature of the spray liquid is increased and the spray liquid falls into the first liquid collecting tank, the spray liquid in the first liquid collecting tank can be introduced into the cooling tower to exchange heat with air, so that the spray liquid is cooled, and the cooled spray liquid is conveyed back to the first spray pipe, thereby realizing the recycling of the spray liquid and saving the spray liquid.

[0012] Optionally, the second spray area is provided with a second spray pipe and a second liquid collecting tank, the absorption refrigerating machine comprises an evaporator, the second spray pipe and the second liquid collecting tank are connected with the evaporator, and the spray liquid in the second liquid collecting tank is conveyed back to the second spray pipe after being cooled by the evaporator.

[0013] In the low-temperature flue gas treatment system, the temperature of the flue gas is reduced after the spray cooling in the first spray area, the flue gas is sprayed and cooled again in the second spray area provided with the second spray pipe, so that the flue gas can reach a lower temperature and has a better adsorption effect when entering the adsorption tower. In addition, since the temperature of the flue gas is relatively low when entering the second spray area, if an electric refrigerating machine is used for refrigeration, a large amount of electric energy will be consumed, and the use of the absorption refrigerating machine to cool the spray liquid is more energy-saving, thereby reducing the operation cost of the system.

[0014] Optionally, the absorption refrigerating machine comprises a generator, a condenser and an absorber, the generator is connected with the outlet of the primary side pipeline, the flue gas after the first temperature reduction is used to provide heat for the generator to drive the absorption refrigerating machine, and the condenser and the absorber are connected with the liquid outlet of the cooling tower to cool the refrigerant in the condenser and the absorber by using the spray liquid discharged from the cooling tower.

[0015] In the low-temperature flue gas treatment system, the condenser and the absorber of the absorption refrigerating machine generate a large amount of heat during operation, and the spray liquid discharged from the cooling tower is used to cool the condenser and the absorber, so that the absorption refrigerating machine can operate more efficiently. At the same time, the condenser and the absorber are cooled by the cooling tower, and a cooling device needs not to be additionally arranged for the absorption refrigerating machine, thereby reducing the operation cost of the whole system.

[0016] Optionally, the spray tower further comprises a third spray zone, the third spray zone is located between the first spray zone and the second spray zone, the flue gas after secondary cooling flows through the first spray zone, the third spray zone and the second spray zone in sequence, the third spray zone is provided with a third spray pipe and a third liquid collecting tank,

[0017] The low-temperature flue gas treatment system further comprises an electric refrigerator, the electric refrigerator is connected with the third liquid collecting tank and the third spray pipe to cool the spray liquid in the third liquid collecting tank, and the cooled spray liquid is transported back to the third spray pipe.

[0018] In the low-temperature flue gas treatment system, the flue gas flows through the first spray zone, the third spray zone and the second spray zone in sequence, and exchanges heat with the spray liquid in the first spray zone, the third spray zone and the second spray zone respectively, so that the temperature can be below room temperature, which is beneficial to the low-temperature adsorption of impurities in the flue gas in the subsequent adsorption tower. In addition, the flue gas is cooled step by step in the first spray zone, the third spray zone and the second spray zone, the heat exchange temperature difference between the spray liquid and the flue gas in each spray zone is small, the heat exchange effect is good, the evaporation loss of the spray liquid is small, the spray liquid is saved, and the flue gas has a good cooling effect.

[0019] Optionally, the electric refrigerator is connected with the cooling tower, and the cooling tower is used for providing cooling water to the electric refrigerator to cool the electric refrigerator.

[0020] In the low-temperature flue gas treatment system, the condenser part of the electric refrigerator generates a lot of heat when it is running, and the cooling water provided by the cooling tower can cool the electric refrigerator, so that the electric refrigerator can work more efficiently. At the same time, the cooling water is used to cool the electric refrigerator without the need to additionally provide a heat dissipation device for the electric refrigerator, thereby reducing the operation cost of the whole system.

[0021] Optionally, the spray tower further comprises a fourth spray zone, the flue gas after secondary cooling flows through the fourth spray zone, the first spray zone and the second spray zone in sequence, the fourth spray zone is provided with a fourth spray pipe and a fourth liquid collecting tank,

[0022] The low-temperature flue gas treatment system comprises a circulating pipe, the circulating pipe is connected between the fourth spray pipe and the fourth liquid collecting tank to circulate the spray liquid in the fourth spray zone.

[0023] In the low-temperature flue gas treatment system, the flue gas after secondary cooling still has a high temperature when entering the fourth spray tower, and the heat exchange temperature difference between the flue gas and the spray liquid is large, part of the spray liquid is evaporated into water vapor after heat exchange with the flue gas, and the water vapor is discharged from the spray tower with the flue gas, and the remaining spray liquid falls into the fourth liquid collecting tank. The circulation pipe can re-transport the spray liquid in the fourth liquid collecting tank back to the fourth spray pipe, realize the recycling of the spray liquid, and save the spray liquid.

[0024] Optionally, the low-temperature flue gas treatment system further comprises a liquid supplementing pipe, one end of the liquid supplementing pipe is connected with the liquid inlet of the cooling tower, and the liquid supplementing pipe is used for supplementing the spray liquid into the cooling tower.

[0025] In the low-temperature flue gas treatment system, the spray liquid is evaporated and lost after heat exchange with air in the cooling tower. Therefore, the liquid supplementing pipe is arranged to supplement the spray liquid in time, so that the flue gas has a good spray cooling effect.

[0026] Optionally, the low-temperature flue gas treatment system comprises a spray liquid treatment device, the spray liquid treatment device is arranged on the liquid supplementing pipe, and the spray liquid treatment device is used for adjusting the pH value of the spray liquid flowing through the liquid supplementing pipe.

[0027] In the low-temperature flue gas treatment system, the spray liquid changes in acidity and alkalinity after heat exchange with gas, and some impurities carried by the gas are mixed into the spray liquid, so that the spray liquid is easy to corrode the conveying pipeline during conveying. The spray liquid treatment device can neutralize and remove the impurities in the spray liquid, weaken the corrosion degree of the conveying pipeline by the spray liquid, prolong the service life of the conveying pipeline, and reduce the maintenance cost of the system.

[0028] Optionally, the spray tower comprises a filler layer, and the filler layer is arranged in the first spray area and the second spray area.

[0029] In the low-temperature flue gas treatment system, the filler layer arranged in the spray area can make the flue gas flow through the filler layer more uniformly in the spray area, the contact area with the spray liquid is larger, and the spray cooling effect is better. BRIEF DESCRIPTION OF DRAWINGS

[0030] Figure 1 is a schematic view of embodiment 1 of the low-temperature flue gas treatment system.

[0031] Figure 2 is a partial schematic view of embodiment 1 of the low-temperature flue gas treatment system.

[0032] Figure 3 is a schematic view of embodiment 2 of the low-temperature flue gas treatment system.

[0033] Figure 4is a partial schematic view of the low-temperature flue gas treatment system of embodiment 2 of the present application.

[0034] Figure 5 is a schematic view of the low-temperature flue gas treatment system of embodiment 3 of the present application.

[0035] Figure 6 is a partial schematic view of the low-temperature flue gas treatment system of embodiment 3 of the present application.

[0036] Figure 7 is a schematic view of the structure of the absorption refrigerating machine of the low-temperature flue gas treatment system of the present application.

[0037] Reference signs:

[0038] 1, heat exchanger; 11, primary side pipeline; 12, secondary side pipeline; 2, absorption refrigerating machine; 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 fitting; 332, first liquid collecting tank; 34, second spray zone; 341, second spray pipe fitting; 342, second liquid collecting tank; 35, third spray zone; 351, third spray pipe fitting; 352, third liquid collecting tank; 36, fourth spray zone; 361, fourth spray pipe fitting; 362, fourth liquid collecting tank; 37, filler layer; 4, cooling tower; 41, liquid inlet; 42, liquid outlet; 5, adsorption tower; 6, regeneration tower; 7, electric refrigerating machine; 8, circulating pipe; 9, liquid supplementing pipe; 10, spray liquid treatment device. DETAILED DESCRIPTION

[0039] Embodiments of the present application are described in detail below, examples of which are shown in the accompanying drawings. The embodiments described below by reference to the drawings are exemplary and are intended to explain the present application, and cannot be understood as limiting the present application.

[0040] As shown in Figures 1-6 , the low-temperature flue gas treatment system of the embodiment of the present application includes a heat exchanger 1, an absorption refrigerating machine 2, a spray tower 3, a cooling tower 4, an adsorption tower 5, and a regeneration tower 6.

[0041] 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 passing in flue gas to be purified, and the secondary side pipeline 12 is used to pass in 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 first temperature reduction is discharged from the outlet of the primary side pipeline 11.

[0042] Specifically, the heat exchanger 1 can be a partition wall heat exchanger 1, and the heat exchange medium can be air. The flue gas to be purified is introduced into the heat exchanger 1 through the inlet of the primary side pipeline 11, and the air is introduced into the heat exchanger 1 through the inlet of the secondary side pipeline 12, and the two are heat exchanged in the heat exchanger 1. The flue gas is discharged from the outlet of the primary side pipeline 11 and is once cooled, and the air is discharged from the outlet of the secondary side pipeline 12 and the temperature is increased. The heat exchanger 1 recovers the waste heat of the flue gas to be purified and realizes the first cooling of the flue gas, reducing the load of the spray tower 3 for cooling the flue gas. At the same time, the hot air at the outlet of the secondary side pipeline 12 can be used for the regeneration tower 6 to realize the regeneration of the adsorbent, saving the energy required for heating the adsorbent and improving the economy of the entire system.

[0043] The absorption refrigeration machine 2 is connected to the outlet of the primary side pipeline 11, and the absorption refrigeration machine 2 is driven by the once cooled flue gas and realizes the secondary cooling of the once cooled flue gas. The flue gas still has a high temperature after being cooled by the heat exchanger 1, and introducing it into the absorption refrigeration machine 2 can be used to drive the absorption refrigeration machine 2. The temperature of the flue gas is lowered again in this process, reducing the load of the spray tower 3 for cooling the flue gas; at the same time, the cold energy generated by the absorption refrigeration machine 2 can be used to cool the spray liquid in the spray tower 3, and the economy of the entire system is good.

[0044] The spray tower 3 includes a flue gas inlet 31, a first spray zone 33, a second spray zone 34, and a flue gas outlet 32. The absorption refrigeration machine 2 is connected to the flue gas inlet 31, and the secondary cooled flue gas enters the spray tower 3 through the flue gas inlet 31 and flows through the first spray zone 33 and the second spray zone 34 in turn 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 zone 34 to cool the spray liquid in the second spray zone 34.

[0045] Specifically, the flue gas inlet 31 is located at the lower part of the spray tower 3, the flue gas outlet 32 is located at the upper part 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 secondary cooled flue gas flows upward and exchanges heat with the spray liquid.

[0046] The flue gas after secondary cooling can enter the spray tower 3 to continue cooling until the temperature is below room temperature. The flue gas flows through the first spray area 33 and the second spray area 34 in the spray tower 3 in turn. The temperature of the flue gas is relatively high in the first spray area 33, and the spray liquid is heated after heat exchange with the flue gas. The spray liquid can be cooled by a cooling tower, an electric refrigerator or the like. After the spray cooling treatment of the flue gas in the first spray area 33, the flue gas flows into the second spray area 34 with a lower temperature. The flue gas needs to be further cooled to below room temperature in the second spray area 34. The spray liquid is cooled by the absorption refrigerator 2 in the second spray area 34. Compared with the use of an electric refrigerator, a large amount of electric energy is saved, and the economy of the system is better.

[0047] The cooling tower 4 is connected with the first spray area 33 and is used for cooling the spray liquid in the first spray area 33. Specifically, the spray liquid after heat exchange with the flue gas in the first spray area 33 can be transported into the cooling tower 4 to be cooled. The cooled spray liquid is transported back to the first spray area 33 to spray and cool the flue gas.

[0048] The adsorption tower 5 is connected with the flue gas outlet 32 of the spray tower 3. The adsorption tower 5 is provided with an adsorbent to adsorb and purify the low-temperature flue gas into clean flue gas. The regenerating tower 6 is connected with the secondary side pipeline 12 to heat the adsorbent in the regenerating tower 6 by the heat exchange medium after heat exchange with the flue gas to be purified.

[0049] After three times of cooling, the flue gas becomes low-temperature flue gas below room temperature. The low-temperature flue gas has a good adsorption effect when contacting with the adsorbent in the adsorption tower 5, and the impurities are more fully removed. The above-mentioned low temperature is room temperature and below room temperature. Preferably, the low temperature is below zero Celsius. More preferably, the low temperature is-20℃ to-15℃.

[0050] The adsorbent can enter the regenerating tower 6 after a period of adsorption. The hot air in the secondary side pipeline 12 enters the regenerating tower 6 to heat the adsorbent in the regenerating tower 6, so that the impurities in the adsorbent are desorbed, and the adsorbent is regenerated and can be used again. This process not only saves energy, but also saves the cost of adsorbent, and the economy of the whole system is better.

[0051] In the low-temperature flue gas treatment system of the embodiment, part of the waste heat in the flue gas to be purified is recovered by a heat exchanger before low-temperature adsorption, and the flue gas is cooled once. Then the flue gas after the first cooling is introduced into an absorption refrigerator to further recover the waste heat and cool the flue gas twice. After the two times of cooling, the flue gas to be purified 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.

[0052] After secondary cooling, the flue gas enters the spray tower and is first cooled by spraying in the first spray zone, then further cooled by spraying in the second spray zone. The spray liquid in the second spray zone can be cooled by the cooling capacity generated by the absorption chiller. Thus, through staged cooling and the cooling capacity of the absorption chiller, the flue gas cooling effect can be improved, and energy utilization efficiency can be increased. The flue gas, after secondary cooling, is cooled to a low-temperature level below room temperature by the spray tower. This low-temperature flue gas has a high adsorption rate in the adsorption tower, achieving a better purification effect. Furthermore, the waste heat recovered by the heat exchanger can be used to heat the regeneration tower to regenerate the adsorbent, realizing the reuse of waste heat and improving the overall system economy.

[0053] In some embodiments, such as Figures 1-6 As shown, the first spray zone 33 is provided with a first spray pipe fitting 331 and a first liquid collection tank 332. The first spray pipe fitting 331 is used to spray spray liquid to spray and cool the flue gas after secondary cooling. The first liquid collection tank 332 is used to receive the spray liquid. The cooling tower 4 includes an inlet 41 connected to the first liquid collection tank 332 and an outlet 42 connected to the first spray pipe fitting 331. The spray liquid in the first liquid collection tank 332 is cooled by the cooling tower 4 and then transported back to the first spray pipe fitting 331.

[0054] Specifically, the first spray zone 33 is located at the lower part of the spray tower 3, and the first spray pipe 331 is located above the first liquid collection tank 332. The first spray pipe 331 sprays spray liquid to cool the flue gas. After exchanging heat with the flue gas, the spray liquid falls into the first liquid collection tank 332. The liquid inlet 41 is located at the upper part of the cooling tower 4, and the liquid outlet 42 is located at the lower part of the cooling tower 4. The spray liquid in the first liquid collection tank 332 enters the cooling tower 4 and exchanges heat with the air inside the cooling tower 4. After heat exchange, the temperature of the spray liquid decreases, and then it is transported back to the first spray pipe 331, realizing the recycling of the spray liquid and saving spray liquid.

[0055] In the first spray zone 33, the temperature of the flue gas is relatively high. Some of the spray liquid evaporates directly when exchanging heat with the flue gas and is discharged from the flue gas outlet 32 ​​with the flue gas. This part of the spray liquid carries away the heat of the flue gas through latent heat. Another part of the spray liquid falls into the first collection tank 332. The temperature of the spray liquid in the first collection tank 332 is relatively high, and it is more economical to cool it through the cooling tower 4.

[0056] In some embodiments, such as Figures 1-6 As shown, the second spray zone 34 is provided with a second spray pipe fitting 341 and a second liquid collection tank 342. The absorption chiller 2 includes an evaporator 23. The second spray pipe fitting 341 and the second liquid collection tank 342 are both connected to the evaporator 23. The spray liquid in the second liquid collection tank 342 is cooled by the evaporator 23 and then transported back to the second spray pipe fitting 341.

[0057] The second spraying area 34 is located above the first spraying area 33, and the second spraying pipe 341 is located above the second liquid collecting groove 342. The second spraying pipe 341 sprays the spraying liquid to cool the flue gas, and the spraying liquid falls into the second liquid collecting groove 342 after heat exchange with the flue gas. The spraying liquid in the second liquid collecting groove 342 can be transported to the evaporator 23 of the absorption chiller 2. In the evaporator 23, the refrigerant evaporates and takes away the heat in the spraying liquid to cool the spraying liquid, and the cooled spraying liquid is transported back to the second spraying pipe 341 to complete the circulation of the spraying liquid.

[0058] The flue gas has been cooled by the first spraying area 33, and its temperature has been reduced. The second spraying pipe 341 is arranged in the second spraying area 34 to cool the flue gas again, so that the flue gas can reach a lower temperature and have a better adsorption effect when entering the adsorption tower 5.

[0059] In the second spraying area 34, the flue gas needs to be finally cooled to a set temperature, and the required spraying liquid temperature is low. Because the lower the final temperature of the electric chiller is under the same temperature reduction range, the more electric energy is consumed. Using the electric chiller to cool the spraying liquid in the second spraying area 34 will consume more electric energy. Using the absorption chiller 2 avoids the above situation and saves the electric energy required for cooling the spraying liquid in the second spraying area 34, so that the system has better economic efficiency.

[0060] In some embodiments, as shown in Figures 1-6 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, and the once-cooled flue gas is used to provide heat for the generator 21 to drive the absorption chiller 2. The condenser 22 and the absorber 24 are connected to the liquid outlet of the cooling tower 4 to cool the refrigerant in the condenser 22 and the absorber 24 by using the spraying liquid discharged from the cooling tower 4.

[0061] Specifically, as shown in Figure 7As shown, the absorption chiller 2 includes a working pair, for example, a water-lithium bromide working pair, and the generator 21 is filled with a lithium bromide aqueous solution. The flue gas at the outlet of the primary side pipeline 11 can heat the generator 21 to evaporate the water in the lithium bromide aqueous solution into water vapor. The water vapor enters the condenser 22, and the cooling water provided by the outlet 42 of the cooling tower 4 cools the condenser 22 to condense the water vapor into liquid water. Subsequently, the liquid water can be depressurized to the evaporation pressure by throttling and enters the evaporator 23. The liquid water evaporates in the evaporator 23 while absorbing the heat in the spray liquid to cool the spray liquid in the second spray zone 34. After the water evaporates in the generator 21, the lithium bromide solution becomes a concentrated solution, which can enter the absorber 24 after throttling. In the absorber 24, the concentrated lithium bromide solution mixes with the water vapor from the evaporator 23, and the concentration of the concentrated 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 solution is easily pumped to the generator 21, and the entire absorption refrigeration process is cycled.

[0062] In the above process, the spray liquid in the second spray zone 34 is cooled by the absorption chiller 2, avoiding the use of a high-power electric chiller and saving energy. At the same time, the condenser 22 and the absorber 24 are cooled by the cooling water provided by the existing cooling tower 4, avoiding the use of other heat dissipation devices to dissipate heat from the absorption chiller 2 and saving the cost of the entire system operation.

[0063] In some embodiments, as shown in Figure 3 , Figure 4 As shown, the spray tower 3 further includes a third spray zone 35 located between the first spray zone 33 and the second spray zone 34. The flue gas after secondary cooling flows through the first spray zone 33, the third spray zone 35, and the second spray zone 34 in sequence. The third spray zone 35 is provided with a third spray pipe 351 and a third liquid collecting tank 352. The low-temperature flue gas treatment system further includes an electric chiller 7 connected to the third liquid collecting tank 352 and the third spray pipe 351 to cool the spray liquid in the third liquid collecting tank 352 and deliver the cooled spray liquid back to the third spray pipe 351.

[0064] Specifically, the third spraying area 35 is located in the middle of the spraying area, the third spraying pipe 351 is located above the third liquid collecting groove 352, the third spraying pipe 351 sprays the spraying liquid to cool the flue gas, and the spraying liquid falls into the third liquid collecting groove after heat exchange with the flue gas. The spraying liquid in the third liquid collecting groove 352 can be transported to the electric refrigerator 7 for cooling, and the cooled spraying liquid is transported back to the third spraying pipe 351 to complete the circulation. The flue gas flows through the first spraying area 33, the third spraying area 35 and the second spraying area 34 in sequence and exchanges heat with the spraying liquid, so that the flue gas can reach a lower temperature, which is beneficial to the subsequent adsorption of impurities in the flue gas. In addition, since the flue gas is cooled step by step in the first spraying area 33, the third spraying area 35 and the second spraying area 34, the heat exchange temperature difference between the spraying liquid and the flue gas in each spraying area is small, the heat exchange effect is good, the evaporation loss of the spraying liquid is small, the spraying liquid is saved, and the flue gas has a good cooling effect.

[0065] In some embodiments, as shown in Figure 3 , Figure 4 The electric refrigerator 7 is connected with the cooling tower 4, and the cooling tower 4 is used to provide cooling water to the electric refrigerator 7 to cool the electric refrigerator 7. Specifically, the cooling water from the outlet 42 of the cooling tower 4 can cool the electric refrigerator 7, for example, the condenser of the electric refrigerator 7. The above-mentioned arrangement does not need to additionally arrange other cooling equipment to cool the electric refrigerator 7, which reduces the operation cost of the whole system and has good economy.

[0066] In some embodiments, as shown in Figure 5 , Figure 6 The spraying tower 3 further comprises a fourth spraying area 36, the flue gas after secondary cooling flows through the fourth spraying area 36, the first spraying area 33 and the second spraying area 34 in sequence, the fourth spraying area 36 is provided with a fourth spraying pipe 361 and a fourth liquid collecting groove 362, and the low-temperature flue gas treatment system comprises a circulating pipe 8 connected between the fourth spraying pipe 361 and the fourth liquid collecting groove 362 to circulate the spraying liquid in the fourth spraying area 36.

[0067] Specifically, the fourth spraying pipe 361 is located above the fourth liquid collecting groove 362, the fourth spraying pipe 361 sprays the spraying liquid to cool the flue gas, and the spraying liquid falls into the fourth liquid collecting groove 362 after heat exchange with the flue gas. The spraying liquid in the fourth liquid collecting groove 362 is transported back to the fourth spraying pipe 361 through the circulating pipe 8. The temperature of the flue gas in the fourth spraying area 36 is high, and when the flue gas contacts the spraying liquid, the spraying liquid evaporates and cools the flue gas through the latent heat, and the evaporated spraying liquid is discharged with the flue gas from the flue gas outlet 32. The purpose of arranging the circulating pipe 8 is to realize the circulation of the spraying liquid in the fourth spraying area 36. At the same time, the fourth spraying area 36 has a pre-cooling effect on the flue gas, which reduces the cooling load of the first spraying area 33 and the second spraying area 34 and reduces the system energy consumption.

[0068] In some embodiments, as shown in Figures 1-6 The low-temperature flue gas treatment system further comprises a liquid supplement pipe 9 and a spray liquid treatment device 10. One end of the liquid supplement pipe 9 is connected to the liquid inlet of the cooling tower 4, for supplementing the spray liquid in the cooling tower 4. The spray liquid treatment device 10 is arranged on the liquid supplement pipe 9, for adjusting the pH value of the spray liquid flowing through the liquid supplement pipe 9.

[0069] Specifically, the liquid supplement pipe 9 can be connected between the liquid inlet 41 of the cooling tower 4 and the first liquid collecting tank 332, for supplementing the spray liquid in the first liquid collecting tank 332 to the cooling tower 4, and adjusting the pH value of the spray liquid by the spray liquid treatment device 10 in the process of supplementing. In addition, clean spray liquid can also be directly supplemented to the cooling tower 4 through the liquid supplement pipe 9 without passing through the spray liquid treatment device 10, which can also play a role in supplementing the spray liquid and adjusting the pH value thereof.

[0070] Since the spray liquid is evaporated in the spray tower 3 and the cooling tower 4, the liquid supplement pipe 9 is arranged to supplement the spray liquid. In addition, the spray liquid changes in acidity and alkalinity after heat exchange with the flue gas, and some impurities carried by the gas are mixed in, which can easily corrode the pipeline during transportation. The spray liquid treatment device 10 is arranged to neutralize and remove the impurities in the supplemented spray liquid.

[0071] In some embodiments, as shown in Figures 1-6 The spray tower 3 comprises a filler layer 37 arranged in the first spray zone 33 and the second spray zone 34.

[0072] As shown in Figure 1 , Figure 2 The filler layer 37 is arranged 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 arrangement of the filler layer makes the distribution of the flue gas in the spray zone more uniform, and the contact area with the spray liquid larger, which has a better heat exchange effect.

[0073] In other embodiments, as shown in Figure 3 , Figure 4 In the third spray zone 35, the filler layer 37 is also arranged between the third spray pipe 351 and the third liquid collecting tank 352. As shown in Figure 5 , Figure 6 In the fourth spray zone 36, the filler layer 37 is also arranged between the fourth spray pipe 361 and the fourth liquid collecting tank 362.

[0074] In some embodiments, as shown in Figures 1-6As shown, the flue gas inlet 31 of the spray tower 3 is located at the lower part of the spray tower 3, the flue gas outlet 32 is located at the upper part of the spray tower 3, and the flow direction of the flue gas in the spray tower 3 is from bottom to top, and the spraying direction of the spray liquid is from top to bottom. The above-mentioned arrangement makes the flue gas and the spray liquid flow in opposite directions, increases the contact time and contact area of the two, makes the heat exchange more sufficient, and the cooling effect of the spray liquid on the flue gas is better.

[0075] The operation process of the low-temperature flue gas treatment system of the embodiment of the present application will be described below taking Example 2 as an example.

[0076] As shown in Figure 3 , Figure 4 As shown, the high-temperature flue gas first flows through the primary side pipeline 11 of the heat exchanger 1, exchanges heat with the air in the secondary side pipeline 12, and the flue gas is cooled for the first time after heat exchange, and the temperature of the secondary side air is increased. The once-cooled flue gas enters the generator 21 of the absorption refrigerator 2 and provides heat to the generator 21 to evaporate the refrigerant therein, and then the flue gas flows out of the generator 21 and is cooled for the second time. The twice-cooled flue gas enters the spray tower 3 through the flue gas inlet 31 and exchanges heat with the spray liquid to achieve the third cooling. The temperature of the thrice-cooled flue gas reaches below room temperature and enters the adsorption tower 5, and the adsorbent in the adsorption tower 5 adsorbs the flue gas below room temperature to remove impurity gases therein, and the flue gas after adsorption becomes clean flue gas that can be directly discharged. The adsorbent can enter the regeneration tower 6 after being used for a period of time, and 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 desorption regeneration of the adsorbent. The regenerated adsorbent is sent back to the adsorption tower 5 for reuse.

[0077] In the spray tower 3, the temperature of the spray liquid is increased after heat exchange with the flue gas, and then enters the cooling tower 4 to exchange heat with air, and the temperature of the spray liquid after heat exchange is reduced and is transported back to the spray tower 3 for spraying again. At the same time, the outlet 42 of the cooling tower 4 discharges the spray liquid with a lower temperature, and the low-temperature spray liquid flows to the electric refrigerator 7 and is used for heat dissipation of the electric refrigerator 7, and the other branch flows to the absorption refrigerator 2 and is used for heat dissipation of the absorber 24 and the condenser 22.

[0078] In the description of the present application, it should be understood that the orientations or positional relationships indicated by the terms "center", "longitudinal", "transverse", "length", "width", "thickness", "upper", "lower", "front", "rear", "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 convenience of describing the present application and simplifying the description, and therefore cannot be understood as indicating or implying that the devices or elements referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as limiting the present application.

[0079] In addition, the terms "first", "second", etc. are used only for descriptive purposes and are not to be construed as indicating or implying relative importance or an ordered ranking of the indicated technical features. Thus, features defined with "first", "second" etc. can include at least one of the features explicitly mentioned or implicitly suggested. In the description of the application, the term "a plurality" means at least two, for example two, three, etc., unless explicitly specified otherwise.

[0080] In the present application, unless specifically defined otherwise, the terms "mounting", "connected", "connection", "fixed", and the like are to be construed broadly, for example, they can be fixed connection, or detachable connection, or integral; they can be mechanical connection, or electrical connection, or communication with each other; they can be direct connection, or indirect connection through intermediate medium; they can be the internal communication of two elements or the interaction relationship between two elements, unless otherwise explicitly defined. 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.

[0081] In the present application, unless specifically defined otherwise, the first feature is "on" or "under" the second feature can be that the first and second features are in direct contact, or the first and second features are in indirect contact through an intermediate medium. Moreover, the first feature "above", "over" and "on" the second feature can be that the first feature is directly above or obliquely above the second feature, or only indicates that the horizontal height of the first feature is higher than that of the second feature. The first feature "below", "under" and "under" the second feature can be that the first feature is directly below or obliquely below the second feature, or only indicates that the horizontal height of the first feature is less than that of the second feature.

[0082] In the present application, the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" etc. mean that the specific features, structures, materials or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present application. In the present specification, the illustrative 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 appropriate manner in any one or more embodiments or examples. In addition, different embodiments or examples described in the specification and the features of different embodiments or examples can be combined and combined by those skilled in the art without contradiction.

[0083] Although the above embodiments have been shown and described, it can be understood that the above embodiments are exemplary and cannot be construed as limiting the present application, and the changes, modifications, replacements and variations of the above embodiments made by those skilled in the art are within the protection scope of the present application.

Claims

1. A low temperature flue gas treatment system, characterized in that, Comprise: a heat exchanger comprising a primary side pipe and a secondary side pipe, the primary side pipe having an inlet for passing in flue gas to be purified and an outlet, the secondary side pipe for passing in a heat exchange medium for heat exchange with the flue gas to primary cool the flue gas, the primary cooled flue gas being discharged from the outlet of the primary side pipe; an absorption refrigerating machine connected to the outlet of the primary side pipe, the absorption refrigerating machine being driven by the primary cooled flue gas and achieving secondary cooling of the primary cooled flue gas; a spray tower comprising a flue gas inlet, a first spray zone, a second spray zone and a flue gas outlet, the absorption refrigerating machine being connected to the flue gas inlet, the secondary cooled flue gas entering the spray tower through the flue gas inlet and flowing through the first spray zone, the second spray zone in sequence to be cooled to low-temperature flue gas below room temperature and being discharged through the flue gas outlet, the absorption refrigerating machine being further connected to the second spray zone for cooling spray liquid in the second spray zone; a cooling tower connected to the first spray zone for cooling spray liquid in the first spray zone; an adsorption tower connected to the flue gas outlet of the spray tower, the adsorption tower being provided with an adsorbent for adsorbing and purifying the low-temperature flue gas into purified flue gas; a regeneration tower connected to the secondary side pipe, 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 for regeneration.

2. The low temperature smoke treatment system of claim 1, wherein, The first spray zone is provided with a first spray pipe and a first liquid collecting tank, the first spray pipe being used for spraying spray liquid to spray cool the secondary cooled flue gas, and the first liquid collecting tank being used for receiving the spray liquid, the cooling tower comprising a liquid inlet communicating with the first liquid collecting tank and a liquid outlet communicating with the first spray pipe, the spray liquid in the first liquid collecting tank being transported back to the first spray pipe after being cooled by the cooling tower.

3. The low temperature flue gas treatment system of claim 2, wherein, The second spray zone is provided with a second spray pipe and a second liquid collecting tank, and the absorption refrigerating machine comprises an evaporator, the second spray pipe and the second liquid collecting tank being connected to the evaporator, the spray liquid in the second liquid collecting tank being transported back to the second spray pipe after being cooled by the evaporator.

4. The low temperature flue gas treatment system of claim 3, wherein, The absorption refrigerating machine comprises a generator, a condenser and an absorber, the generator being connected to the outlet of the primary side pipe, the primary cooled flue gas being used to provide heat for the generator to drive the absorption refrigerating machine, and the condenser and the absorber being connected to the liquid outlet of the cooling tower to cool refrigeration working medium in the condenser and the absorber by using the spray liquid discharged from the cooling tower.

5. The low temperature flue gas treatment system of claim 3, wherein, The spray tower further comprises a third spray zone between the first spray zone and the second spray zone, the secondary cooled flue gas flowing through the first spray zone, the third spray zone and the second spray zone in sequence, the third spray zone being provided with a third spray pipe and a third liquid collecting tank, The low-temperature flue gas treatment system further comprises an electric refrigerator connected with the third collecting tank and the third spraying pipe to cool the spraying liquid in the third collecting tank and deliver the cooled spraying liquid back to the third spraying pipe.

6. The low temperature flue gas treatment system of claim 5, wherein, The electric refrigerator is connected with the cooling tower, and the cooling tower is used to provide cooling water for the electric refrigerator to dissipate heat of the electric refrigerator.

7. The low temperature flue gas treatment system of claim 3, wherein, The spraying tower further comprises a fourth spraying area, and the flue gas after secondary cooling flows through the fourth spraying area, the first spraying area and the second spraying area in sequence. The low-temperature flue gas treatment system comprises a circulating pipe connected between the fourth spraying pipe and the fourth collecting tank to circulate the spraying liquid in the fourth spraying area.

8. The low temperature flue gas treatment system of claim 2, wherein, The spraying tower further comprises a liquid supplementing pipe, one end of the liquid supplementing pipe being connected with a liquid inlet of the cooling tower to supplement the spraying liquid in the cooling tower.

9. The low temperature flue gas treatment system of claim 8, wherein, The spraying tower further comprises a spraying liquid treatment device arranged on the liquid supplementing pipe, the spraying liquid treatment device being used to adjust the pH value of the spraying liquid flowing through the liquid supplementing pipe.

10. The low temperature flue gas treatment system of any of claims 1-9, wherein, The spraying tower comprises a filler layer arranged in the first spraying area and the second spraying area.

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