Flue gas low temperature purification system

Abstract

The present application relates to the technical field of flue gas purification and discloses a flue gas low-temperature purification system, which comprises a spray tower, an adsorption tower, a regeneration tower, a heat exchanger and an absorption refrigerating machine. The spray tower is used for cooling flue gas into low-temperature flue gas with subzero temperature. The adsorption tower is used for adsorbing and purifying the low-temperature flue gas into clean flue gas. The regeneration tower is used for heating and regenerating adsorbents. The regeneration tower is connected with the adsorption tower to make the adsorbents circulate between the adsorption tower and the regeneration tower. The heat exchange medium, which is introduced into the cold side inlet of the heat exchanger, exchanges heat with the flue gas discharged from the boiler flue and is then supplied into the regeneration tower. The generator inlet of the absorption refrigerating machine is connected with the hot side outlet. The evaporator inlet of the absorption refrigerating machine is connected with the spray liquid outlet of the spray tower. The evaporator outlet of the absorption refrigerating machine is connected with the spray liquid inlet of the spray tower to cool the spray liquid. The flue gas low-temperature purification system can utilize the flue gas waste heat multiple times and reduce the energy consumption of the system.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of flue gas purification, in particular to a flue gas low-temperature purification system. BACKGROUND

[0002] The low-temperature method pollutant integrated removal technology is a comprehensive flue gas pollutant treatment technology. Based on the principle of flue gas low-temperature adsorption denitration, SO2 and residual moisture are removed through a desulfurization adsorption tower, and SO3, Hg, HCl, HF, VOCs and a small amount of NOx are also adsorbed. After the desulfurization and dehumidification, the flue gas is cooled to a subzero temperature zone, and then enters a low-temperature denitration adsorption tower. NOx is deeply adsorbed and removed at low temperature, achieving the two goals of 'integrated removal' and 'near-zero emission' of pollutants.

[0003] In the related art, if the flue gas is to be deeply cooled to below room temperature, a conventional electric refrigerator needs to consume a large amount of electric energy. In particular, the lower the flue gas cooling temperature, the smaller the refrigeration coefficient of the electric refrigerator, and the more the electric energy consumed. Similarly, the adsorbent in the regenerator needs to be heated to a high temperature of 300℃ or above to meet the regeneration temperature requirement, so a high-grade steam or other medium needs to be used to heat it, which consumes a large amount of energy and uses a heater to heat the adsorbent in the regenerator. Both of them consume a large amount of energy and are poor in economy. SUMMARY

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

[0005] On the path of flue gas emission, the flue gas temperature is gradually reduced, and if it is not utilized, a large amount of waste heat in the flue gas will be wasted. In the related art, a large amount of high-temperature heat medium (such as clean air at about 400℃) needs to be introduced into the heating section of the regenerator to heat the adsorbent. Therefore, the inventors use flue gas waste heat to heat clean air, and introduce the heat-exchanged clean air into the heating section to utilize the flue gas waste heat and avoid energy waste.

[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 flue gas low-temperature purification system which can utilize flue gas waste heat multiple times and has the advantage of low energy consumption.

[0007] The flue gas low-temperature purification system of the present application comprises:

[0008] a spray tower having a flue gas inlet and a flue gas outlet, the spray tower being configured to cool flue gas introduced from the flue gas inlet to low-temperature flue gas at a subzero temperature;

[0009] an adsorption tower having an adsorbent inlet, an adsorbent outlet and a flue gas inlet connected with the flue gas outlet, the adsorption tower being used for adsorbing purification of the low-temperature flue gas into clean flue gas;

[0010] a regenerating tower including a heating section used for heating regeneration of the adsorbent therein, the regenerating tower having a regenerating inlet connected with the adsorbent outlet and a regenerating outlet connected with the adsorbent inlet, so as to circulate the adsorbent between the adsorption tower and the regenerating tower;

[0011] a heat exchanger having a hot side inlet connected with the boiler flue, a hot side outlet, a cold side inlet used for feeding a heat exchange medium and a cold side outlet connected with the heating section, the heat exchange medium fed into the cold side inlet of the heat exchanger being used for heat exchange with the flue gas discharged from the boiler flue and then fed into the heating section;

[0012] an absorption refrigerating machine, a generator inlet of the absorption refrigerating machine being connected with the hot side outlet, an evaporator inlet of the absorption refrigerating machine being connected with the spray liquid outlet of the spray tower, and an evaporator outlet of the absorption refrigerating machine being connected with the spray liquid inlet of the spray tower, so as to cool the spray liquid in the evaporator of the absorption refrigerating machine.

[0013] The flue gas low-temperature purification system of the present application can first utilize the flue gas discharged from the boiler flue to exchange heat with clean air, utilize the clean air after heat exchange to heat the adsorbent in the heating section, realize the first utilization of the flue gas waste heat, then utilize the flue gas after heat exchange as a driving source to drive the absorption refrigerating machine, so as to produce cold energy, thereby realizing the second utilization of the flue gas waste heat. In addition, the cold energy produced by the absorption refrigerating machine can be used to cool the spray liquid of the spray tower, thereby replacing the original refrigeration equipment (such as a refrigerating machine) of the spray tower and reducing the consumption of electric energy.

[0014] In addition, the flue gas after heat exchange still has certain heat, the inventor utilizes the flue gas after heat exchange as a driving source to drive the absorption refrigerating machine to work, the cold energy produced by the absorption refrigerating machine can also be used to cool the spray liquid of the spray tower, thereby further utilizing the heat of the flue gas and avoiding excessive consumption of electric energy by the purification system.

[0015] Optionally, a generator outlet of the absorption refrigerating machine is connected with the flue gas inlet of the spray tower.

[0016] The flue gas used as a driving source in the flue gas low-temperature purification system of the present application is fed into the spray tower after use for spray treatment, thereby avoiding pollution of the environment by the flue gas discharged into the atmosphere. In addition, the temperature of the flue gas is much lower than the temperature of the flue gas directly discharged from the boiler, thereby facilitating the spray cooling treatment of the spray tower.

[0017] Optionally, the regeneration tower further comprises a preheating section above the heating section, the preheating section having a first downcomer and a first medium flow channel, the heating section having a second downcomer and a second medium flow channel, the first downcomer being used for guiding the falling of the adsorbent in the preheating section, the second downcomer being used for guiding the falling of the adsorbent in the heating section, the first medium flow channel being used for passing the first heat exchange medium into the adsorbent in the first downcomer, and the second medium flow channel being used for passing the second heat exchange medium into the adsorbent in the second downcomer.

[0018] The preheating section and the heating section of the flue gas low-temperature purification system adopt indirect heat exchange, which can avoid the mutual interference of water vapor generated in the cooling process of high-temperature air or adsorbent, and can also avoid the mixing of impurities in the air into the adsorbent, thereby affecting the adsorption effect of the adsorbent.

[0019] Optionally, the regeneration tower further comprises a cooling section below the heating section, the cooling section having a third downcomer and a third medium flow channel, the third downcomer being used for guiding the falling of the adsorbent in the cooling section, and the flue gas outlet of the adsorption tower being communicated with the third medium flow channel, so that the flue gas discharged from the flue gas outlet of the adsorption tower passes into the third medium flow channel to cool the adsorbent in the third downcomer.

[0020] After the adsorbent in the heating section of the flue gas low-temperature purification system is exchanged with high-temperature air to be desorbed, the adsorbent can flow to the third downcomer. At this time, the adsorbent has a certain temperature. It has been found through research that the adsorption and purification effect of the flue gas is weak if the adsorbent at this temperature directly flows to the adsorption tower. Therefore, low-temperature flue gas is passed into the cooling section to cool the adsorbent in the third downcomer, so that the adsorption effect of the adsorbent in the adsorption tower can be improved.

[0021] Optionally, the heat exchanger comprises a shell and a heat exchange pipe arranged in the shell, an inner cavity of the shell constitutes a hot side space communicated with the hot side inlet and the hot side outlet, and an inner cavity of the heat exchange pipe constitutes a cold side space communicated with the cold side inlet and the cold side outlet.

[0022] In the flue gas low-temperature purification system, the heat exchange between the flue gas discharged from the boiler flue and the clean air in the heat exchanger is indirect, so as to avoid the pollution of the air.

[0023] Optionally, the flue gas low-temperature purification system further comprises a cold energy recovery assembly, and at least one of the smoke outlet, the flue gas outlet and the smoke outlet of the cooling section is connected with the cold energy recovery assembly.

[0024] The cold energy recovery assembly can be used for recovering cold energy in flue gas discharged from the flue gas outlet, flue gas discharged from the cooling section and flue gas discharged from the flue gas discharge port, so that waste of cold energy of flue gas is avoided.

[0025] Optionally, the spray cooling tower comprises a plurality of spray assemblies, and the spray tower has a plurality of spray zones arranged in sequence along the flue gas flow direction in the spray tower, and the plurality of spray assemblies correspond to the plurality of spray zones one by one, and are used for spraying and cooling flue gas flowing through the plurality of spray zones in sequence to low-temperature flue gas at subzero temperature.

[0026] The flue gas low-temperature purification system of the application can use a plurality of spray assemblies to spray and cool different spray zones in the spray tower, so that the flue gas in the spray tower is gradually cooled along the flow direction thereof until the temperature of the flue gas is reduced to below 0 DEG C.

[0027] Optionally, the cold energy recovery assembly comprises a cold energy recovery tower and a cold energy exchanger, the cold energy recovery tower is connected with the flue gas discharge port of the adsorption tower and the cold energy exchanger, circulating liquid in the cold energy exchanger exchanges cold energy with the clean flue gas in the cooling recovery tower to recover cold energy in the clean flue gas, and the cold energy exchanger is connected with at least one of the plurality of spray zones to indirectly cool spray liquid discharged from the at least one spray zone and supply the cooled spray liquid to a spray assembly corresponding to the at least one spray zone.

[0028] The flue gas low-temperature purification system of the application can use a cold energy recovery assembly to recover cold energy in flue gas, and the recovered cold energy can be used to cool spray liquid discharged from a spray zone again, and the cooled spray liquid is supplied into the corresponding spray zone, so that the cold energy is recovered and reused.

[0029] Optionally, the plurality of spray zones comprise a first-stage spray zone, a second-stage spray zone, a third-stage spray zone and a fourth-stage spray zone arranged in sequence along the flue gas flow direction, and the plurality of spray assemblies comprise a first-stage spray assembly, a second-stage spray assembly, a third-stage spray assembly and a fourth-stage spray assembly, and the cold energy exchanger is connected with a spray liquid outlet of the second-stage spray zone and a spray liquid inlet of the second-stage spray assembly.

[0030] The flue gas low-temperature purification system of the application divides the spray tower into four spray zones, and further optimizes the effect of step-by-step cooling of the spray tower, so that the temperature difference between adjacent two-stage spray zones is not too large, and the cooling of spray liquid does not need to consume too much cold energy.

[0031] Optionally, an evaporator inlet of the absorption refrigerating machine is connected with a spray liquid outlet of the fourth-stage spray zone, and an evaporator outlet of the absorption refrigerating machine is connected with a spray liquid inlet of the fourth-stage spray assembly.

[0032] The cold energy generated by the absorption refrigerating machine of the flue gas low-temperature purification system can be used to cool the spray liquid of the fourth spray assembly, so that the use of a low-temperature refrigerating machine can be avoided, and accordingly the electric energy consumption of the system can be reduced. BRIEF DESCRIPTION OF DRAWINGS

[0033] Figure 1 is a structural schematic diagram of the flue gas low-temperature purification system of the present application.

[0034] Figure 2 is a structural schematic diagram of the flue gas low-temperature purification system of the present application.

[0035] Figure 3 is a structural schematic diagram of the regeneration tower of the flue gas low-temperature purification system of the present application.

[0036] Figure 4 is a sectional schematic diagram of the gas-permeable outer shell of the flue gas low-temperature purification system of the present application.

[0037] REFERENCE SIGNS:

[0038] gas-permeable outer shell 100;

[0039] spray tower 1; flue gas inlet 11; flue gas outlet 12; first spray zone 131; second spray zone 132; third spray zone 133; fourth spray zone 134; first spray assembly 141; second spray assembly 142; third spray assembly 143; fourth spray assembly 144;

[0040] adsorption tower 2; flue gas inlet 21; flue gas outlet 22; adsorbent inlet 23; adsorbent outlet 24;

[0041] regeneration tower 3; preheating section 31; first downcomer 311; first medium flow channel 312; heating section 32; second downcomer 321; second medium flow channel 322; cooling section 33; third downcomer 331; third medium flow channel 332; regeneration inlet 34; regeneration outlet 35;

[0042] heat exchanger 4; hot side inlet 41; hot side outlet 42; cold side inlet 43; cold side outlet 44;

[0043] absorption refrigerating machine 5; generator inlet 51; generator outlet 52; evaporator inlet 53; evaporator outlet 54;

[0044] cold energy recovery assembly 6; cold energy recovery tower 61; cold energy exchanger 62;

[0045] medium-temperature refrigerating machine 7. DETAILED DESCRIPTION

[0046] Embodiments of the present application are described in detail below with reference to the attached drawing figures, wherein the embodiments described are by way of illustration only and are not intended to be limiting of the application.

[0047] As shown in Figures 1-4 The flue gas low-temperature purification system of the present application comprises a spray tower 1, an adsorption tower 2, a regeneration tower 3, a heat exchanger 4 and an absorption refrigerating machine 5.

[0048] The spray tower 1 has a flue gas inlet 11 and a flue gas outlet 12, and is used for cooling the flue gas into low-temperature flue gas at subzero temperature. The adsorption tower 2 has an adsorbent inlet 23, an adsorbent outlet 24 and a flue gas inlet 21 connected with the flue gas outlet 12, and is used for adsorbing and purifying the low-temperature flue gas into clean flue gas. The regeneration tower 3 comprises a heating section 32 for heating and regenerating the adsorbent therein, and has a regeneration inlet 34 connected with the adsorbent outlet 24 and a regeneration outlet 35 connected with the adsorbent inlet 23, so as to circulate the adsorbent between the adsorption tower 2 and the regeneration tower 3.

[0049] It can be understood that the flue gas inlet 11 of the spray tower 1 is connected with the boiler flue, so that the flue gas discharged from the boiler flue can be introduced into the spray tower 1, and the flue gas is cooled by spraying in the spray tower 1.

[0050] Preferably, the temperature of the low-temperature flue gas is -20℃ to -15℃.

[0051] The heat exchanger 4 has a hot-side inlet 41 connected with the boiler flue, a hot-side outlet 42, a cold-side inlet 43 for introducing a heat exchange medium and a cold-side outlet 44 connected with the heating section 32, and the heat exchange medium introduced into the cold-side inlet 43 is supplied into the heating section 32 after heat exchange with the flue gas discharged from the boiler flue. The generator inlet 51 of the absorption refrigerating machine 5 is connected with the hot-side outlet 42, the evaporator inlet 53 of the absorption refrigerating machine 5 is connected with the spray liquid outlet of the spray tower 1, and the evaporator outlet 54 of the absorption refrigerating machine 5 is connected with the spray liquid inlet of the spray tower 1, so as to cool the spray liquid in the evaporator of the absorption refrigerating machine 5.

[0052] It can be understood that part of the flue gas discharged from the boiler flue is introduced into the spray tower 1, and part of the flue gas is introduced into the heat exchanger 4 through the hot-side inlet 41, so as to exchange heat with the heat exchange medium in the heat exchanger 4. In the heat exchanger 4, the flue gas after heat exchange is introduced into the generator inlet 51 of the absorption refrigerating machine 5 through the hot-side outlet 42, i.e. the flue gas after heat exchange is used as a power source to drive the absorption refrigerating machine 5, and the absorption refrigerating machine 5 can be used to produce cold energy, thereby realizing multiple utilization of the flue gas waste heat.

[0053] In use (taking a lithium bromide absorption chiller as an example), the lithium bromide solution in the absorber is pumped into the generator by a solution pump, a high-temperature heat source (high-temperature flue gas, etc.) is used to heat the lithium bromide solution in the generator, so that the lithium bromide solution is heated to evaporate to form lithium bromide gas, and the lithium bromide gas is introduced into the condenser, the lithium bromide gas is condensed and liquefied in the condenser and is introduced into the evaporator after being reduced in pressure by the throttling device, and the lithium bromide solution is evaporated in the evaporator and can absorb the heat of the surrounding environment, thereby achieving cooling of the spray liquid introduced into the evaporator.

[0054] It should be noted that the heat exchange medium can be air, high-temperature resistant oil, molten salt, etc., wherein the air can be purified air, and the heat exchange medium in the subsequent description of the present application is taken as an example of purified air, which is referred to as "purified air" hereinafter.

[0055] Therefore, the flue gas low-temperature purification system of the present application can first utilize the flue gas discharged from the boiler flue to exchange heat with the purified air, utilize the purified air after heat exchange to heat the adsorbent in the heating section 32, realize the first utilization of the flue gas waste heat, and then utilize the flue gas after heat exchange as a power source to drive the absorption chiller 5 to produce cold energy, thereby realizing the second utilization of the flue gas waste heat. In addition, the cold energy produced by the absorption chiller 5 can cool the spray liquid of the spray tower 1, replacing the original refrigeration equipment (such as a chiller, etc.) of the spray tower 1, and reducing the consumption of electric energy.

[0056] Optionally, the generator outlet 52 of the absorption chiller 5 is connected with the flue gas inlet 11 of the spray tower 1. That is to say, the flue gas as a driving source in the flue gas low-temperature purification system of the present application is introduced into the spray tower 1 for spray treatment after use, avoiding pollution of the environment by discharging the flue gas into the atmosphere. The temperature of the flue gas is much lower than that of the flue gas directly discharged from the boiler, thus facilitating the spray cooling treatment of the spray tower 1.

[0057] Optionally, the regenerator 3 further comprises a preheating section 31 located above the heating section 32, the preheating section 31 has a first downcomer 311 and a first medium flow channel 312, the heating section 32 has a second downcomer 321 and a second medium flow channel 322, the first downcomer 311 is used to guide the adsorbent to fall in the preheating section 31, the second downcomer 321 is used to guide the adsorbent to fall in the heating section 32, the first medium flow channel 312 is used to introduce a first heat exchange medium into the adsorbent in the first downcomer, and the second medium flow channel 322 is used to introduce a second heat exchange medium into the adsorbent in the second downcomer.

[0058] Specifically, as shown in Figure 1 and Figure 3As shown, the preheating section 31 is located above the heating section 32, and the regeneration inlet 34 is connected to the first feed pipe 311 so that the adsorbent in the adsorption tower 2 enters the first feed pipe 311 through the adsorbent outlet 24 and the regeneration inlet 34.

[0059] It is understood that the clean air after heat exchange in the heating section 32, introduced by the heat exchanger 4, serves as the second heat exchange medium. This second heat exchange medium in the heating section 32 is used to exchange heat with the adsorbent in the second feed pipe 321. Preferably, the first medium flow channel 312 connects to the second medium flow channel 322. The second heat exchange medium after heat exchange in the heating section 32 forms the first heat exchange medium and is introduced into the first medium flow channel 312 to preheat the adsorbent in the first feed pipe 311, thus avoiding heat waste.

[0060] Preferably, the heat exchanger 4 includes a shell and heat exchange tubes disposed within the shell. The inner cavity of the shell forms a hot-side space communicating with the hot-side inlet 41 and the hot-side outlet 42, and the inner cavity of the heat exchange tubes forms a cold-side space communicating with the cold-side inlet 43 and the cold-side outlet 44. In the flue gas low-temperature purification system of the present invention, the heat exchange between the flue gas discharged from the boiler flue and the clean air in the heat exchanger 4 is indirect to avoid air pollution.

[0061] It should be noted that the preheating section 31 and heating section 32 of the flue gas low-temperature purification system of the present invention both adopt indirect heat exchange, which can not only avoid mutual interference between the high-temperature air or the water vapor generated by the adsorbent during the cooling process, but also prevent impurities in the air from mixing into the adsorbent and affecting the adsorption effect of the adsorbent.

[0062] Optionally, such as Figures 1-3 As shown, the regeneration tower 3 also includes a cooling section 33 located below the heating section 32. The cooling section 33 has a third feed pipe 331 and a third medium flow channel 332. The third feed pipe 331 is used to guide the adsorbent to fall in the cooling section 33. The flue gas outlet 22 of the adsorption tower 2 is connected to the third medium flow channel 332 so that the flue gas discharged from the flue gas outlet 22 of the adsorption tower 2 enters the third medium flow channel 332 to cool the adsorbent in the third feed pipe 331.

[0063] It is understood that after the adsorbent in the heating section 32 of the flue gas low-temperature purification system of the present invention exchanges heat with the high-temperature air and is decomposed, it can flow to the third feed pipe 331. At this time, the adsorbent has a certain temperature. Studies have found that if the adsorbent at this temperature is directly flowed to the adsorption tower 2, the adsorption and purification effect on the flue gas will be weak. Therefore, by introducing low-temperature clean flue gas into the cooling section 33, the adsorbent in the third feed pipe 331 is cooled, so that the adsorbent can be conveniently used in the adsorption tower 2.

[0064] Optionally, the flue gas low-temperature purification system of the present invention further includes a cold energy recovery component 6, and at least one of the flue gas outlet 12, the flue gas outlet 22 and the flue gas outlet of the cooling section 33 is connected to the cold energy recovery component 6.

[0065] Preferably, such as Figure 1 As shown, the cold energy recovery component 6 is connected to the exhaust port 12, the flue gas outlet 22, and the exhaust port of the cooling section 33.

[0066] In other words, the low-temperature flue gas purification system of the present invention can utilize the cold energy recovery component 6 to recover the cold energy in the flue gas discharged from the exhaust port 12, the flue gas discharged from the flue gas outlet 22, and the flue gas discharged from the cooling section 33, thereby avoiding the waste of flue gas cold energy.

[0067] In addition, such as Figure 3 As shown, the first medium flow channel 312, the second medium flow channel 322, and the third medium flow channel 332 in the flue gas low-temperature purification system of the present invention are all serpentine flow channels, which ensures the flow time of the heat exchange medium in the first medium flow channel 312, the second medium flow channel 322, and the third medium flow channel 332, thereby improving the heat exchange effect with the adsorbent.

[0068] It should be noted that, as Figure 4 As shown, the adsorbent can be filled inside the permeable shell 100 for adsorption. The adsorbent can be granular or powdered, or it can be an adsorbent body made of powder or granular adsorbent, such as a spherical or cylindrical body formed by binding powder or granular adsorbent with a binder. Of course, a protective shell can be further formed on the outside of the adsorbent body, such as a permeable membrane covering the outside of the adsorbent body, to improve the strength of the adsorbent body. The permeable shell has vents, through which flue gas can enter the permeable shell. The flue gas can pass through the gaps between adjacent adsorbents and / or the pores of the adsorbent itself, thereby reducing direct collisions, friction and wear between adsorbents, and dust generation. The permeable shell can be in the shape of a sphere, cylinder, or other rotating body, wherein the diameter of the permeable shell 100 is 10mm-100mm, and the diameter of the adsorbent is 1mm-10mm.

[0069] Optionally, the spray cooling tower includes multiple spray components, and the spray tower 1 has multiple spray zones. The multiple spray zones are arranged sequentially and at intervals along the flue gas flow direction in the spray tower 1. The multiple spray components correspond one-to-one with the multiple spray zones, and are used to spray and cool the flue gas flowing through the multiple spray zones sequentially to a low temperature of sub-zero.

[0070] The flue gas low-temperature purification system of the present invention can use multiple spray components to spray and cool different spray zones in the spray tower 1, so that the flue gas in the spray tower 1 is cooled down step by step along its flow direction until the flue gas temperature is reduced to below 0°C.

[0071] Optionally, the cold energy recovery assembly 6 comprises a cold energy recovery tower 61 and a cold energy exchanger 62, the cold energy recovery tower 61 is connected with the flue gas outlet 12 of the adsorption tower 2 and the cold energy exchanger 62, the circulating liquid in the cold energy exchanger 62 exchanges cold energy with the clean flue gas in the cooling recovery tower to recover the cold energy in the clean flue gas, the cold energy exchanger 62 is connected with at least one of the plurality of spray zones to indirectly cool the spray liquid discharged from the at least one spray zone and supply the cooled spray liquid to the spray assembly corresponding to the at least one spray zone.

[0072] It can be understood that the cold energy exchanger 62 can be connected with one spray zone or a plurality of spray zones to cool the spray liquid discharged from the corresponding spray zone. The circulating liquid with cold energy in the cold energy exchanger 62 is formed by directly exchanging heat with the clean flue gas entering the cold energy recovery tower 61 in the cold energy recovery tower 61. The cold energy exchanger 62 can be provided with two pipelines, one of which is used to pass in the heat-exchanged circulating liquid (temperature close to 0°C), and the other is used to pass in the spray liquid discharged from the spray zone after heat exchange with the flue gas (temperature higher than 0°C), so that indirect heat exchange can occur in the cold energy exchanger 62, so that the heat-exchanged spray liquid in the cold energy exchanger 62 can be used in the spray zone again, thereby realizing the recovery and reuse of the cold energy of the flue gas.

[0073] Therefore, the flue gas low-temperature purification system of the present application can recover the cold energy in the flue gas by using the cold energy recovery assembly 6, and can be used again to cool the spray liquid discharged from the spray zone, and then pass the cooled spray liquid into the corresponding spray zone, thereby realizing the recovery and reuse of the cold energy.

[0074] Optionally, as shown in Figure 1 The plurality of spray zones comprise a first-stage spray zone 131, a second-stage spray zone 132, a third-stage spray zone 133 and a fourth-stage spray zone 134 arranged in sequence along the flue gas flow direction; the plurality of spray assemblies comprise a first-stage spray assembly 141, a second-stage spray assembly 142, a third-stage spray assembly 143 and a fourth-stage spray assembly 144; the cold energy exchanger 62 is connected with the spray liquid outlet of the second-stage spray zone 132 and the spray liquid inlet of the second-stage spray assembly 142.

[0075] That is, the second-stage spray assembly 142 cools the flue gas to 30-35°C, and the clean flue gas in the adsorption tower 2 cools the spray liquid in the second-stage spray zone 132 from 40-44°C to 30-34°C. Specifically, the clean flue gas in the adsorption tower 2 exchanges heat with the circulating liquid of the cold energy recovery tower 61 in the cold energy recovery tower 61, and then the heat-exchanged circulating liquid exchanges heat with the spray liquid in the second-stage spray zone 132 in the cold energy exchanger 62, so that the spray liquid in the second-stage spray zone 132 is cooled from 40-44°C to 30-34°C.

[0076] It can be understood that the flue gas flows in the direction from bottom to top after entering the spray cooling tower, that is, the flue gas enters the spray cooling tower and passes through the first spray zone 131, the second spray zone 132, the third spray zone 133 and the fourth spray zone 134 in turn. Since the initial temperature of the flue gas (80-100℃) is high, the spray liquid in the first spray assembly 141 is used to spray and cool the flue gas by using normal temperature liquid in the first spray zone 131. At this time, the temperature of the spray liquid in the first spray assembly 141 rises to 50-54℃, and since the temperature of the spray liquid is high, it is directly heat-exchanged with the circulating liquid of the cold energy recovery tower 61, the temperature difference of heat exchange is large, which can cause poor heat exchange effect and easy energy waste. Preferably, the flue gas purification system of the present application further comprises a water cooler connected between the spray liquid outlet of the first spray zone 131 and the liquid inlet of the first spray assembly 141. The spray liquid discharged from the first spray zone 131 is cooled by the water cooler and then returned to the first spray assembly 141.

[0077] In addition, the third spray assembly 143 is provided with a medium-temperature refrigerator 7 for cooling the spray liquid after heat exchange in the third spray zone 133.

[0078] Optionally, the evaporator inlet 53 of the absorption refrigerator 5 is connected with the spray liquid outlet of the fourth spray zone 134, and the evaporator outlet 54 of the absorption refrigerator 5 is connected with the spray liquid inlet of the fourth spray assembly 144.

[0079] The cold energy generated by the absorption refrigerator 5 of the flue gas low-temperature purification system of the present application can be used to cool the spray liquid of the fourth spray assembly 144, so that the use of a low-temperature refrigerator can be avoided, and the power consumption of the system can be reduced accordingly.

[0080] Therefore, the flue gas low-temperature purification system of the present application divides the spray tower 1 into four spray zones, further optimizes the effect of step-by-step temperature reduction of the spray tower 1, and avoids that the temperature difference between adjacent two-stage spray zones is too large, which can cause excessive consumption of cold energy for cooling the spray liquid.

[0081] 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.

[0082] In addition, the terms "first", "second", etc. are used only for the purpose of description and do not imply or imply relative importance or imply the number of the technical features indicated. Therefore, the features defined as "first", "second" 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.

[0083] 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, or it can be the internal communication or interaction 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.

[0084] 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.

[0085] In the present application, the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" mean that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present application. In the present specification, the illustrative description of the above terms does 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, those skilled in the art can combine and combine different embodiments or examples described in the present specification and the features of different embodiments or examples without contradiction.

[0086] Although the above embodiments have been shown and described, it is 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 scope of the present application.

Claims

1. A flue gas cryogenic cleaning system characterized by, The application relates to a low-temperature flue gas absorption and cooling system. The system comprises: a spray tower having a flue gas inlet and a flue gas outlet, the spray tower being used for cooling flue gas into low-temperature flue gas of zero temperature; an adsorption tower having an adsorbent inlet, an adsorbent outlet and a flue gas inlet connected with the flue gas outlet, the adsorption tower being used for adsorbing and purifying low-temperature flue gas into clean flue gas; a regeneration tower comprising a heating section used for heating and regenerating adsorbent, the regeneration tower having a regeneration inlet connected with the adsorbent outlet and a regeneration outlet connected with the adsorbent inlet, so that adsorbent circulates between the adsorption tower and the regeneration tower; a heat exchanger having a hot side inlet connected with a boiler flue, a hot side outlet, a cold side inlet used for feeding a heat exchange medium and a cold side outlet connected with the heating section, the heat exchange medium fed into the cold side inlet of the heat exchanger being used for exchanging heat with flue gas discharged from the boiler flue and then being fed into the heating section; 2. The flue gas cryogenic cleaning system of claim 1, wherein, an absorption refrigerating machine, a generator inlet of the absorption refrigerating machine being connected with the hot side outlet, an evaporator inlet of the absorption refrigerating machine being connected with a spray liquid outlet of the spray tower, and an evaporator outlet of the absorption refrigerating machine being connected with a spray liquid inlet of the spray tower, so as to cool spray liquid in the evaporator of the absorption refrigerating machine.

3. The flue gas cryogenic cleaning system of claim 2, wherein, A generator outlet of the absorption refrigerating machine is connected with the flue gas inlet of the spray tower.

4. The flue gas cryogenic cleaning system of claim 3, wherein, The regeneration tower further comprises a preheating section above the heating section, the preheating section having a first downcomer and a first medium flow channel, the heating section having a second downcomer and a second medium flow channel, the first downcomer being used for guiding adsorbent to fall in the preheating section, the second downcomer being used for guiding adsorbent to fall in the heating section, the first medium flow channel being used for feeding a first heat exchange medium into adsorbent in the first downcomer, and the second medium flow channel being used for feeding a second heat exchange medium into adsorbent in the second downcomer.

5. The flue gas cryogenic cleaning system of claim 1, wherein, The regeneration tower further comprises a cooling section below the heating section, the cooling section having a third downcomer and a third medium flow channel, the third downcomer being used for guiding adsorbent to fall in the cooling section, and the flue gas outlet of the adsorption tower being communicated with the third medium flow channel, so that flue gas discharged from the flue gas outlet of the adsorption tower is fed into the third medium flow channel to cool adsorbent in the third downcomer.

6. The flue gas cryogenic cleaning system of claim 1, wherein, The heat exchanger comprises a shell and a heat exchange pipe arranged in the shell, an inner cavity of the shell constituting a hot side space communicated with the hot side inlet and the hot side outlet, and an inner cavity of the heat exchange pipe constituting a cold side space communicated with the cold side inlet and the cold side outlet. The system further comprises a cold energy recovery assembly, at least one of the flue gas outlet, the flue gas outlet of the adsorption tower and the flue gas outlet of the cooling section being connected with the cold energy recovery assembly.

7. The flue gas cryogenic cleaning system of claim 6, wherein, The spray cooling tower comprises a plurality of spray assemblies, a plurality of spray zones are arranged in the spray tower, and the plurality of spray zones are arranged in sequence along the flue gas flow direction in the spray tower. The plurality of spray assemblies correspond to the plurality of spray zones one by one, and are used for spraying and cooling the flue gas flowing through the plurality of spray zones in sequence into low-temperature flue gas at zero temperature.

8. The flue gas cryogenic cleaning system of claim 7, wherein, The cold energy recovery assembly comprises a cold energy recovery tower and a cold energy exchanger. The cold energy recovery tower is connected with the flue gas outlet of the adsorption tower and the cold energy exchanger. The circulating liquid in the cold energy exchanger exchanges cold energy with the clean flue gas in the cooling recovery tower to recover the cold energy in the clean flue gas. The cold energy exchanger is connected with at least one of the plurality of spray zones to indirectly cool the spray liquid discharged from the at least one spray zone and supply the cooled spray liquid to the spray assembly corresponding to the at least one spray zone.

9. The flue gas cryogenic cleaning system of claim 8, wherein, The plurality of spray zones comprise a first-stage spray zone, a second-stage spray zone, a third-stage spray zone and a fourth-stage spray zone arranged in sequence along the flue gas flow direction; The plurality of spray assemblies comprise a first-stage spray assembly, a second-stage spray assembly, a third-stage spray assembly and a fourth-stage spray assembly; The cold energy exchanger is connected with the spray liquid outlet of the second-stage spray zone and the spray liquid inlet of the second-stage spray assembly.

10. The flue gas cryogenic cleaning system of claim 9, wherein, The evaporator inlet of the absorption refrigerating machine is connected with the spray liquid outlet of the fourth-stage spray zone, and the evaporator outlet of the absorption refrigerating machine is connected with the spray liquid inlet of the fourth-stage spray assembly.

Images