Waste alkali liquid desulfurization tail gas treatment system and method

Abstract

The invention discloses a waste lye desulfurization tail gas treatment system and method.The waste lye desulfurization tail gas treatment system comprises a desulfurization unit, a tail gas pretreatment unit and a tail gas co-treatment unit; the input end of the desulfurization unit is connected with a waste alkali liquid discharging device, the liquid output end of the desulfurization unit is connected with a waste alkali liquid resource utilization device, and the tail gas co-processing unit comprises a first heat exchanger, a flame arrester, a combined heat and power generation boiler and a flue gas treatment device; the cold side input end of the first heat exchanger is connected with the output end of the tail gas pretreatment unit, the hot side input end of the first heat exchanger is connected with the first output end of the combined heat and power generation boiler, and the cold side output end of the first heat exchanger is connected with the input end of the flame arrester. And finally, up-to-standard emission is realized, the treatment energy consumption is effectively reduced, meanwhile, the construction, operation and maintenance cost of a tail gas incinerator is saved, and the requirements of energy conservation and emission reduction are met.

Description

Technical Field

[0001] This application relates to the field of alkali treatment technology, and in particular to a waste alkali desulfurization tail gas treatment system and method. Background Technology

[0002] Large-scale integrated utilization projects of coal, oil, and gas resources generate a large amount of waste alkaline liquid during the alkaline washing of acidic gas. The main units that generate acidic gas are residue catalytic thermal cracking (DCC) units and methanol-to-olefins (MTO) units. Taking the residue catalytic thermal cracking unit as an example, the waste alkaline liquid it emits contains a large amount of sulfides, ammonia nitrogen, and benzene compounds. Most of the sulfides are catalytically oxidized to sodium thiosulfate and sodium sulfate in the desulfurization reactor through aeration. A small amount of sulfur ions are in the form of hydrogen sulfide, most of the ammonia nitrogen is in the form of ammonia gas, and the vast majority of benzene compounds are directly stripped and carried into the desulfurization tail gas.

[0003] Conventional biological treatment devices are effective at removing low concentrations of ammonia, hydrogen sulfide, and readily biodegradable organic matter from waste gas. However, due to the unique cyclic structure of benzene compounds, conventional biological treatment processes are almost ineffective at removing them. Therefore, using biological treatment alone to treat desulfurization tail gas often leads to excessive benzene levels at the total discharge outlet of the treatment facility. Furthermore, because the ammonia content in desulfurization tail gas is high, simple biological treatment processes cannot achieve compliance. Therefore, it is necessary to design a waste alkaline solution desulfurization tail gas treatment method to remove ammonia and benzene compounds from the desulfurization tail gas, thereby meeting increasingly stringent environmental protection requirements. Summary of the Invention

[0004] This application provides a waste alkali desulfurization tail gas treatment system and method, which solves the technical problem in the prior art where the high content of ammonia and benzene series compounds in the desulfurization tail gas leads to substandard tail gas emissions.

[0005] In a first aspect, embodiments of the present invention provide a waste alkali solution desulfurization tail gas treatment system, comprising a desulfurization unit, a tail gas pretreatment unit, and a tail gas co-treatment unit; the input end of the desulfurization unit is connected to a waste alkali solution discharge device, the liquid output end of the desulfurization unit is connected to a waste alkali solution resource utilization device, the gas output end of the desulfurization unit is connected to the input end of the tail gas pretreatment unit, and the output end of the tail gas pretreatment unit is connected to the tail gas co-treatment unit; the tail gas co-treatment unit includes a first heat exchanger, a flame arrester, a cogeneration boiler, and a flue gas treatment device; the cold side input end of the first heat exchanger is connected to the tail gas pretreatment unit. The output terminals of the first heat exchanger are connected to each other; the hot-side input terminal of the first heat exchanger is connected to the first output terminal of the cogeneration boiler; the cold-side output terminal of the first heat exchanger is connected to the input terminal of the flame arrester; the hot-side output terminal of the first heat exchanger is connected to the flue gas treatment device; the output terminal of the flame arrester is connected to the first input terminal of the cogeneration boiler; the second output terminal of the cogeneration boiler is connected to the flue gas treatment device; the desulfurization unit is configured to remove sulfides from waste alkaline solution; the tail gas pretreatment unit is configured to perform preliminary treatment on tail gas pollutants; and the tail gas co-treatment unit is configured to further treat tail gas pollutants.

[0006] In conjunction with the first aspect, in one possible implementation, the desulfurization unit includes a regulating tank, a catalyst injection facility, a desulfurization aeration blower, and a desulfurization reactor; the input end of the regulating tank is connected to the waste alkali liquid discharge device, and the output end of the regulating tank is connected to the input end of the catalyst injection facility; the output end of the catalyst injection facility is connected to the liquid input end of the desulfurization reactor, and the desulfurization aeration blower is connected to the gas input end of the desulfurization reactor; the gas output end of the desulfurization reactor is connected to the input end of the tail gas pretreatment unit, and the liquid output end of the desulfurization reactor is connected to the waste alkali liquid resource utilization device; the desulfurization unit further includes a booster pump; the input end of the booster pump is connected between the regulating tank and the catalyst injection facility.

[0007] In conjunction with the first aspect, in one possible implementation, the tail gas pretreatment unit includes an acid washing tower, a sulfuric acid dosing facility, a biological treatment stage, a tail gas conveying fan, and a condensate collection and conveying device; the first input end of the acid washing tower is connected to the gas output end of the desulfurization reactor, and the output end of the acid washing tower is connected to the input end of the biological treatment stage; the output end of the biological treatment stage is connected to the input end of the tail gas conveying fan, the first output end of the tail gas conveying fan is connected to the input end of the condensate collection and conveying device, the second output end of the tail gas conveying fan is connected to the cold side input end of the first heat exchanger, and the output end of the condensate collection and conveying device is connected to the input end of the regulating tank; the sulfuric acid dosing facility is connected to the second input end of the acid washing tower; the tail gas pretreatment unit further includes a circulating pump; one end of the circulating pump is connected to the third input end of the acid washing tower, and the other end of the circulating pump is connected to the fourth input end of the acid washing tower.

[0008] In conjunction with the first aspect, in one possible implementation, the exhaust gas co-treatment unit further includes a second heat exchanger, the first input end of which is connected to the second output end of the cogeneration boiler, and the first output end of which is connected to the flue gas treatment device; fresh air is input into the second input end of the second heat exchanger, and the second output end of the second heat exchanger is connected to the second input end of the cogeneration boiler.

[0009] In conjunction with the first aspect, in one possible implementation, the exhaust gas pretreatment unit further includes a second biological treatment stage; the second biological treatment stage is connected between the first biological treatment stage and the exhaust gas conveying fan.

[0010] In conjunction with the first aspect, in one possible implementation, the exhaust gas co-treatment unit includes a flue gas booster fan; the flue gas booster fan is connected between the first output end of the cogeneration boiler and the hot-side input end of the first heat exchanger.

[0011] In conjunction with the first aspect, in one possible implementation, the exhaust gas co-treatment unit further includes a lower explosive limit (LEL) detector and an emergency shut-off valve assembly; one end of the LEL detector is connected between the second output end of the exhaust gas conveying fan and the cold-side input end of the first heat exchanger, the other end of the LEL detector is connected to the first input end of the emergency shut-off valve assembly, and the first output end of the emergency shut-off valve assembly is connected to the first heat exchanger; the second input end of the emergency shut-off valve assembly is connected between the LEL detector and the cold-side input end of the first heat exchanger, and the second output end of the emergency shut-off valve assembly is connected to other exhaust gas treatment devices.

[0012] In conjunction with the first aspect, in one possible implementation, multiple LEL (Lower Limit of Explosion) detectors are provided, and the multiple LEL detectors are connected in parallel.

[0013] Secondly, embodiments of the present invention provide a method for treating waste alkali desulfurization tail gas, applicable to the waste alkali desulfurization tail gas treatment system described in the first aspect or in combination with any possible implementation of the first aspect, comprising the following steps: Desulfurization unit treatment: the discharged waste alkali is input into a regulating tank to adjust the pH and flow rate; the waste alkali is transported to a catalyst injection facility by a booster pump, and a catalyst is injected in proportion; the waste alkali containing the catalyst is transported to the desulfurization reactor, and at the same time, the desulfurization aeration blower introduces air into the desulfurization reactor, and the waste alkali undergoes a catalytic oxidation reaction in the reactor to remove sulfides and generate elemental sulfur; the desulfurized waste alkali is transported to a resource utilization device, and the sulfur-containing tail gas enters the tail gas pretreatment unit; tail gas pretreatment: the sulfur-containing tail gas enters the acid washing tower, and sulfuric acid is injected into the acid washing tower circulating liquid by a sulfuric acid dosing facility to adjust the pH of the acid washing tower circulating liquid, for removing alkaline gases and residual H2S; the tail gas after acid washing enters the desulfurization unit. The system enters a biological treatment stage, where microorganisms degrade organic sulfur and small molecule pollutants. A second biological treatment stage is added for further biological purification. The treated exhaust gas is pressurized by an exhaust gas conveying fan, and after condensate separation, it is fed into a condensate collection and conveying device. The condensate in the condensate collection and conveying device is then recycled back to a regulating tank. The dried exhaust gas is then transported to the exhaust gas co-treatment unit. In the co-treatment stage, the exhaust gas enters the cold side of the first heat exchanger, where it exchanges heat with the high-temperature flue gas from the cogeneration boiler. The heated exhaust gas then passes through a flame arrester and enters the cogeneration boiler for combustion, thus completely decomposing pollutants. One path of the high-temperature flue gas from the boiler is cooled on the hot side of the first heat exchanger before entering the flue gas treatment device. The other path of the high-temperature flue gas from the boiler is preheated with fresh air on the hot side of the second heat exchanger before entering the flue gas treatment device. The flue gas treatment device performs dust removal and denitrification, achieving emission standards.

[0014] In conjunction with the second aspect, in one possible implementation, the exhaust gas co-treatment also includes a safety interlock. The LEL (Lower Explosion Limit) detector monitors the concentration of combustible gas in the exhaust gas in real time. If the concentration exceeds the limit, the emergency shut-off valve group is triggered to switch the exhaust gas to the backup exhaust gas treatment device.

[0015] One or more technical solutions provided in this application have at least the following technical effects:

[0016] This invention employs a waste alkali desulfurization tail gas treatment system and method. The waste alkali desulfurization tail gas treatment system includes a desulfurization unit, a tail gas pretreatment unit, and a tail gas co-treatment unit. The input end of the desulfurization unit is connected to a waste alkali discharge device, the liquid output end of the desulfurization unit is connected to a waste alkali resource utilization device, the gas output end of the desulfurization unit is connected to the input end of the tail gas pretreatment unit, and the output end of the tail gas pretreatment unit is connected to the tail gas co-treatment unit. The desulfurization unit is configured to remove sulfides from the waste alkali, the tail gas pretreatment unit is configured to perform preliminary treatment of tail gas pollutants, and the tail gas co-treatment unit is configured to further treat tail gas pollutants. This application solves the technical problem of high ammonia and benzene series content in desulfurization tail gas, leading to substandard emissions, in existing technologies. After simple pretreatment, the desulfurization tail gas is co-treated by a cogeneration boiler, ultimately achieving compliant emissions, effectively reducing energy consumption, and eliminating the construction and operation costs of a tail gas incinerator, thus meeting energy conservation and emission reduction requirements. Attached Figure Description

[0017] To more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings used in the description of the embodiments of this application will be briefly introduced below. Obviously, the drawings described below are some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0018] Figure 1 A schematic diagram of a waste alkali desulfurization tail gas treatment system provided in an embodiment of this application;

[0019] Figure 2 A flowchart of a waste alkali desulfurization tail gas treatment method provided in an embodiment of this application.

[0020] Icons: 1-Desulfurization unit; 11-Regulating tank; 12-Catalyst dosing facility; 13-Desulfurization aeration fan; 14-Desulfurization reactor; 15-Boost pump; 2-Tail gas pretreatment unit; 21-Acid washing tower; 22-Sulfuric acid dosing facility; 23-Biological treatment stage 1; 24-Tail gas conveying fan; 25-Condensate collection and conveying device; 26-Circulating pump; 27-Biological treatment stage 2; 3-Tail gas co-treatment unit; 31-First heat exchanger; 32-Flame arrestor; 33-Cogeneration boiler; 34-Flue gas treatment device; 35-Flue gas booster fan; 36-Second heat exchanger; 37-LEL lower explosion limit detector; 38-Emergency shut-off valve assembly. Detailed Implementation

[0021] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of this application. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0022] In the description of the embodiments of this application, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing the embodiments of this application and for simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this application. The terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance. Furthermore, the terms "installed," "connected," and "linked" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in the embodiments of this application according to the specific circumstances.

[0023] This invention provides a waste alkali solution desulfurization tail gas treatment system, such as... Figure 1 As shown, the system includes a desulfurization unit 1, a tail gas pretreatment unit 2, and a tail gas co-treatment unit 3. The input end of the desulfurization unit 1 is connected to the waste alkali liquid discharge device, the liquid output end of the desulfurization unit 1 is connected to the waste alkali liquid resource utilization device, the gas output end of the desulfurization unit 1 is connected to the input end of the tail gas pretreatment unit 2, and the output end of the tail gas pretreatment unit 2 is connected to the tail gas co-treatment unit 3. The tail gas co-treatment unit 3 includes a first heat exchanger 31, a flame arrester 32, a cogeneration boiler 33, and a flue gas treatment device. 34; The cold-side input end of the first heat exchanger 31 is connected to the output end of the exhaust gas pretreatment unit 2, the hot-side input end of the first heat exchanger 31 is connected to the first output end of the cogeneration boiler 33, the cold-side output end of the first heat exchanger 31 is connected to the input end of the flame arrester 32, and the hot-side output end of the first heat exchanger 31 is connected to the flue gas treatment device 34; the output end of the flame arrester 32 is connected to the first input end of the cogeneration boiler 33; and the second output end of the cogeneration boiler 33 is connected to the flue gas treatment device 34. The desulfurization unit 1 is configured to remove sulfides from the waste alkaline solution, the exhaust gas pretreatment unit 2 is configured to perform preliminary treatment on the exhaust gas pollutants, and the exhaust gas co-treatment unit 3 is configured to further treat the exhaust gas pollutants.

[0024] For example, desulfurization unit 1 removes sulfides from waste alkaline solution and transports the desulfurized waste alkaline solution to downstream treatment devices. The desulfurized tail gas enters tail gas pretreatment unit 2, where some easily degradable organic matter, such as ammonia and hydrogen sulfide, is removed. The pretreated tail gas then exchanges heat with the flue gas discharged from the cogeneration boiler 33 before being co-fired in the boiler furnace. This application solves the problem of excessively long treatment processes and high treatment costs caused by the complex composition of desulfurized tail gas. After simple pretreatment, the desulfurized tail gas is co-treated by the cogeneration boiler 33, ultimately achieving compliant emissions, effectively reducing energy consumption, and eliminating the construction and maintenance costs of tail gas incinerators, thus meeting energy conservation and emission reduction requirements.

[0025] In the embodiments of this application, such as Figure 1 As shown, the desulfurization unit 1 includes a regulating tank 11, a catalyst injection facility 12, a desulfurization aeration blower 13, and a desulfurization reactor 14. The input end of the regulating tank 11 is connected to the waste alkali liquid discharge device, and the output end of the regulating tank 11 is connected to the input end of the catalyst injection facility 12. The output end of the catalyst injection facility 12 is connected to the liquid input end of the desulfurization reactor 14, and the desulfurization aeration blower 13 is connected to the gas input end of the desulfurization reactor 14. The gas output end of the desulfurization reactor 14 is connected to the input end of the tail gas pretreatment unit 2, and the liquid output end of the desulfurization reactor 14 is connected to the waste alkali liquid resource utilization device. The desulfurization unit 1 also includes a booster pump 15. The input end of the booster pump 15 is connected between the regulating tank 11 and the catalyst injection facility 12.

[0026] For example, the waste alkaline liquid from the catalytic pyrolysis of residual oil produced by the residual oil enters the regulating tank 11 for homogenization, and is then transported to the desulfurization reactor 14 by the booster pump 15. The liquid-phase catalyst, which is uniformly and continuously output by the catalyst injection facility 12, is fully mixed with the waste alkaline liquid on the inlet pipeline of the booster pump 15 and then enters the desulfurization reactor 14. The desulfurization aeration blower 13 continuously aerates the desulfurization reactor 14 during the reaction. The outlet of the desulfurization aeration blower 13 is equipped with a vent valve, which can adjust the aeration rate according to the air volume required by the desulfurization reactor 14. The gas output end of the desulfurization reactor 14 is connected to the acid washing tower 21.

[0027] For example, the desulfurization reactor 14 is a plug flow reactor, in which the booster pump 15, catalyst injection facility 12, and desulfurization aeration blower 13 all operate continuously. To increase the reaction residence time, the desulfurization reactor 14 can be configured with multiple reactors connected in series. The gas output end of the desulfurization reactor 14 is equipped with an online oxygen content detector, which can adjust the aeration rate in real time according to the oxygen utilization rate.

[0028] In the embodiments of this application, such as Figure 1As shown, the exhaust gas pretreatment unit 2 includes an acid washing tower 21, a sulfuric acid dosing facility 22, a biological treatment stage 23, an exhaust gas conveying fan 24, and a condensate collection and conveying device 25. The first input end of the acid washing tower 21 is connected to the gas output end of the desulfurization reactor 14, and the output end of the acid washing tower 21 is connected to the input end of the biological treatment stage 23. The output end of the biological treatment stage 23 is connected to the input end of the exhaust gas conveying fan 24, the first output end of the exhaust gas conveying fan 24 is connected to the input end of the condensate collection and conveying device 25, the second output end of the exhaust gas conveying fan 24 is connected to the cold side input end of the first heat exchanger 31, and the output end of the condensate collection and conveying device 25 is connected to the input end of the regulating tank 11. The sulfuric acid dosing facility 22 is connected to the second input end of the acid washing tower 21. The exhaust gas pretreatment unit 2 also includes a circulating pump 26. One end of the circulating pump 26 is connected to the third input end of the acid washing tower 21, and the other end of the circulating pump 26 is connected to the fourth input end of the acid washing tower 21.

[0029] For example, the acid washing tower 21 removes high-concentration ammonia from the tail gas through a matching circulating pump 26 and sulfuric acid dosing facility 22. An online pH meter is installed on the outlet pipeline of the circulating pump 26. After the acidic substances in the circulating pump 26 react with the ammonia, the pH of the circulating liquid will rise, requiring periodic replenishment of the system with strong inorganic acid. Simultaneously, the nearly saturated ammonium sulfate solution needs to be periodically discharged from the acid washing tower 21 to ensure the ammonia removal rate. Residual ammonia, hydrogen sulfide, and easily degradable organic matter in the tail gas exiting the acid washing tower 21 can be effectively removed in the first stage of biological treatment 23 and the second stage of biological treatment 27. The tail gas conveying fan 24 continuously provides power for tail gas conveying. During the tail gas conveying process, the saturated water vapor in the tail gas condenses and is returned to the regulating tank 11 of the desulfurization unit 1 through the condensate collection and conveying device 25.

[0030] For example, the ammonia content in the desulfurization tail gas at the inlet of acid washing tower 21 is approximately 500 mg / m³. 3 The ammonia content in the desulfurization tail gas at the outlet of pickling tower 21 is approximately 50 mg / m³. 3 .

[0031] In the embodiments of this application, such as Figure 1 As shown, the exhaust gas co-processing unit 3 also includes a second heat exchanger 36. The first input end of the second heat exchanger 36 is connected to the second output end of the cogeneration boiler 33, and the first output end of the second heat exchanger 36 is connected to the flue gas treatment device 34. Fresh air is input into the second input end of the second heat exchanger 36, and the second output end of the second heat exchanger 36 is connected to the second input end of the cogeneration boiler 33.

[0032] In the embodiments of this application, such as Figure 1 As shown, the exhaust gas pretreatment unit 2 also includes a biological treatment stage 27; the biological treatment stage 27 is connected between the biological treatment stage 23 and the exhaust gas conveying fan 24.

[0033] In the embodiments of this application, such as Figure 1 As shown, the exhaust gas co-processing unit 3 includes a flue gas booster fan 35; the flue gas booster fan 35 is connected between the first output end of the cogeneration boiler 33 and the hot side input end of the first heat exchanger 31.

[0034] For example, the flue gas booster fan 35 is a variable frequency fan, which can adjust the flue gas volume at the hot side input of the first heat exchanger 31 according to the temperature requirements of the cold side output of the first heat exchanger 31. The combined heat and power boiler 33 is a highly efficient energy utilization technology that simultaneously produces electricity and chemical steam through a single energy input. Its core advantage lies in the cascade utilization of energy, with a comprehensive efficiency of 70%-90%, far exceeding that of traditional stand-alone power generation (approximately 35%-50%). It combines energy saving, environmental protection, and economy. In the event of a single boiler interlock trip, it can urgently stop the power-side heat load, cleverly achieving boiler hot standby. While improving the reliability of chemical steam use, it ensures that the boiler operates at high load for the vast majority of the time, further saving energy.

[0035] For example, a flame arrester 32 is provided after the first heat exchanger 31 to prevent backfire when the boiler furnace air pressure and the tail gas delivery pipeline pressure are abnormal.

[0036] In the embodiments of this application, such as Figure 1 As shown, the exhaust gas co-treatment unit 3 also includes a lower explosive limit detector 37 and an emergency shut-off valve assembly 38; one end of the lower explosive limit detector 37 is connected between the second output end of the exhaust gas conveying fan 24 and the cold side input end of the first heat exchanger 31, the other end of the lower explosive limit detector 37 is connected to the first input end of the emergency shut-off valve assembly 38, the first output end of the emergency shut-off valve assembly 38 is connected to the first heat exchanger 31; the second input end of the emergency shut-off valve assembly 38 is connected between the lower explosive limit detector 37 and the cold side input end of the first heat exchanger 31, and the second output end of the emergency shut-off valve assembly 38 is connected to other exhaust gas treatment devices.

[0037] In the embodiments of this application, such as Figure 1 As shown, multiple LEL (Lower Limit of Explosion) detectors 37 are provided, and multiple LEL detectors 37 are connected in parallel.

[0038] This invention provides a method for treating waste alkaline solution desulfurization tail gas, such as... Figure 2 As shown, this method is applicable to waste alkali desulfurization tail gas treatment systems and includes the following steps:

[0039] Desulfurization Unit 1 processes: Waste alkaline solution is fed into regulating tank 11 to adjust pH and flow rate; the waste alkaline solution is then transported to catalyst injection facility 12 via booster pump 15, where catalyst is injected in proportion; the catalyst-containing waste alkaline solution is transported to desulfurization reactor 14, while simultaneously, desulfurization aeration blower 13 introduces air into desulfurization reactor 14, where the waste alkaline solution undergoes catalytic oxidation to remove sulfides and generate elemental sulfur; the desulfurized waste alkaline solution is then transported to resource utilization device, and the sulfur-containing tail gas enters tail gas pretreatment unit 2;

[0040] Tail gas pretreatment: Sulfur-containing tail gas enters acid washing tower 21, and sulfuric acid dosing facility 22 injects sulfuric acid to adjust the pH of the circulating liquid in acid washing tower 21 to remove alkaline gases and residual H2S; the tail gas after acid washing enters biological treatment stage 1 23, where organic sulfur and small molecule pollutants are degraded by microorganisms, and a second biological treatment stage 27 is added for deep biological purification; the treated tail gas is pressurized by tail gas conveying fan 24, and after condensate separation, it is input into condensate collection and conveying device 25, and the condensate in condensate collection and conveying device 25 is returned to regulating tank 11 for recycling, and the dried tail gas is transported to tail gas co-treatment unit 3;

[0041] Co-treatment of exhaust gas: The exhaust gas enters the cold side input end of the first heat exchanger 31, where it exchanges heat with the high-temperature flue gas discharged from the cogeneration boiler 33 to raise its temperature. The heated exhaust gas then enters the cogeneration boiler 33 for combustion via the flame arrester 32, thereby completely decomposing pollutants. One path of the high-temperature flue gas generated by the boiler is cooled on the hot side of the first heat exchanger 31 before entering the flue gas treatment device 34. The other path of the high-temperature flue gas generated by the boiler is preheated with fresh air on the hot side of the second heat exchanger 36 before entering the flue gas treatment device 34. The flue gas treatment device 34 performs dust removal and denitrification to achieve emission standards.

[0042] In the embodiments of this application, such as Figure 2 As shown, a safety interlock is also set up in the exhaust gas co-treatment. The LEL (Lower Explosion Limit) detector 37 monitors the concentration of combustible gas in the exhaust gas in real time. If the concentration exceeds the limit, the emergency shut-off valve group 38 is triggered to switch the exhaust gas to the backup exhaust gas treatment device.

[0043] For example, the hot-side input end of the first heat exchanger 31 is connected to the output end of the flue gas booster fan 35. The second output end of the cogeneration boiler 33 mixes with the first input end of the second heat exchanger 36 before being connected to the flue gas treatment device. The cold-side output end of the first heat exchanger 31 is connected to the input end of the flame arrester 32. The output end of the flame arrester 32 mixes with the second output end of the second heat exchanger 36 before being connected to the second input end of the cogeneration boiler 33. Fresh air is introduced into the second input end of the second heat exchanger 36.

[0044] For example, the system is equipped with a lower explosion limit detector 37 and an emergency shut-off valve assembly 38. When the gas in the cogeneration boiler 33 exceeds the lower explosion limit of the lower explosion limit detector 37, the gas supply path to the boiler can be cut off in an emergency through the emergency shut-off valve assembly 38, and the gas can be urgently sent to other waste gas treatment devices, thereby ensuring the safety of the system.

[0045] The various embodiments in this specification are described in a progressive manner. For the same or similar parts between the various embodiments, please refer to each other. Each embodiment focuses on describing the differences from other embodiments.

[0046] The above embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit this application. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of this application.

Claims

1. A waste alkali solution desulfurization tail gas treatment system, characterized in that, It includes a desulfurization unit (1), a tail gas pretreatment unit (2), and a tail gas co-treatment unit (3); The input end of the desulfurization unit (1) is connected to the waste alkali liquid discharge device, the liquid output end of the desulfurization unit (1) is connected to the waste alkali liquid resource utilization device, the gas output end of the desulfurization unit (1) is connected to the input end of the tail gas pretreatment unit (2), and the output end of the tail gas pretreatment unit (2) is connected to the tail gas co-treatment unit (3). The exhaust gas co-processing unit (3) includes a first heat exchanger (31), a flame arrester (32), a cogeneration boiler (33), and a flue gas treatment device (34); The cold side input end of the first heat exchanger (31) is connected to the output end of the exhaust gas pretreatment unit (2), the hot side input end of the first heat exchanger (31) is connected to the first output end of the cogeneration boiler (33), the cold side output end of the first heat exchanger (31) is connected to the input end of the flame arrester (32), and the hot side output end of the first heat exchanger (31) is connected to the flue gas treatment device (34). The output end of the flame arrester (32) is connected to the first input end of the cogeneration boiler (33); The second output end of the cogeneration boiler (33) is connected to the flue gas treatment device (34); The desulfurization unit (1) is configured to remove sulfides from the waste alkaline solution, the tail gas pretreatment unit (2) is configured to perform preliminary treatment on the tail gas pollutants, and the tail gas co-treatment unit (3) is configured to perform further treatment on the tail gas pollutants.

2. The waste alkali desulfurization tail gas treatment system according to claim 1, characterized in that, The desulfurization unit (1) includes a regulating tank (11), a catalyst injection facility (12), a desulfurization aeration blower (13), and a desulfurization reactor (14); The input end of the regulating tank (11) is connected to the waste alkali discharge device, and the output end of the regulating tank (11) is connected to the input end of the catalyst injection facility (12). The output end of the catalyst injection facility (12) is connected to the liquid input end of the desulfurization reactor (14), and the desulfurization aeration blower (13) is connected to the gas input end of the desulfurization reactor (14). The gas output end of the desulfurization reactor (14) is connected to the input end of the tail gas pretreatment unit (2), and the liquid output end of the desulfurization reactor (14) is connected to the waste alkali liquid resource utilization device. The desulfurization unit (1) also includes a booster pump (15); The input end of the booster pump (15) is connected between the regulating tank (11) and the catalyst injection facility (12).

3. The waste alkali liquid desulfurization tail gas treatment system according to claim 2, characterized in that, The exhaust gas pretreatment unit (2) includes an acid washing tower (21), a sulfuric acid dosing facility (22), a biological treatment stage (23), an exhaust gas conveying fan (24), and a condensate collection and conveying device (25); The first input end of the acid washing tower (21) is connected to the gas output end of the desulfurization reactor (14), and the output end of the acid washing tower (21) is connected to the input end of the biological treatment section (23). The output end of the biological treatment section (23) is connected to the input end of the exhaust gas conveying fan (24), the first output end of the exhaust gas conveying fan (24) is connected to the input end of the condensate collection and conveying device (25), the second output end of the exhaust gas conveying fan (24) is connected to the cold side input end of the first heat exchanger (31), and the output end of the condensate collection and conveying device (25) is connected to the input end of the regulating tank (11). The sulfuric acid dosing facility (22) is connected to the second input end of the acid washing tower (21); The exhaust gas pretreatment unit (2) also includes a circulation pump (26); One end of the circulating pump (26) is connected to the third input end of the pickling tower (21), and the other end of the circulating pump (26) is connected to the fourth input end of the pickling tower (21).

4. The waste alkali liquid desulfurization tail gas treatment system according to claim 3, characterized in that, The exhaust gas co-processing unit (3) further includes a second heat exchanger (36), the first input end of the second heat exchanger (36) is connected to the second output end of the cogeneration boiler (33), and the first output end of the second heat exchanger (36) is connected to the flue gas treatment device (34). Fresh air is introduced into the second input terminal of the second heat exchanger (36), and the second output terminal of the second heat exchanger (36) is connected to the second input terminal of the cogeneration boiler (33).

5. The waste alkali desulfurization tail gas treatment system according to claim 3, characterized in that, The exhaust gas pretreatment unit (2) also includes a biological treatment stage (27); The second biological treatment stage (27) is connected between the first biological treatment stage (23) and the exhaust gas conveying fan (24).

6. The waste alkali desulfurization tail gas treatment system according to claim 4, characterized in that, The exhaust gas co-treatment unit (3) includes a flue gas booster fan (35); The flue gas booster fan (35) is connected between the first output end of the cogeneration boiler (33) and the hot side input end of the first heat exchanger (31).

7. The waste alkali desulfurization tail gas treatment system according to claim 3, characterized in that, The exhaust gas co-treatment unit (3) also includes an LEL (lower explosion limit) detector (37) and an emergency shut-off valve assembly (38); One end of the LEL lower explosion limit detector (37) is connected between the second output end of the exhaust gas conveying fan (24) and the cold side input end of the first heat exchanger (31), and the other end of the LEL lower explosion limit detector (37) is connected to the first input end of the emergency shut-off valve group (38), and the first output end of the emergency shut-off valve group (38) is connected to the first heat exchanger (31). The second input terminal of the emergency shut-off valve assembly (38) is connected between the LEL lower explosion limit detector (37) and the cold side input terminal of the first heat exchanger (31), and the second output terminal of the emergency shut-off valve assembly (38) is connected to other waste gas treatment devices.

8. The waste alkali desulfurization tail gas treatment system according to claim 7, characterized in that, Multiple LEL (lower explosion limit) detectors (37) are provided, and multiple LEL detectors (37) are connected in parallel.

9. A method for treating waste alkaline solution desulfurization tail gas, characterized in that, The waste alkali desulfurization tail gas treatment system as described in any one of claims 1-8 includes the following steps: Desulfurization unit (1) process: The discharged waste alkali liquid is fed into the regulating tank (11) to adjust the pH and flow rate; the waste alkali liquid is transported to the catalyst injection facility (12) by the booster pump (15) and the catalyst is injected in proportion; the waste alkali liquid containing the catalyst is transported to the desulfurization reactor (14), and at the same time, the desulfurization aeration blower (13) introduces air into the desulfurization reactor (14). The waste alkali liquid undergoes a catalytic oxidation reaction in the reactor to remove sulfides and generate elemental sulfur; the desulfurized waste alkali liquid is transported to the resource utilization device, and the sulfur-containing tail gas enters the tail gas pretreatment unit (2); Tail gas pretreatment: Sulfur-containing tail gas enters the acid washing tower (21), and sulfuric acid dosing facility (22) injects sulfuric acid to adjust the pH of the circulating liquid in the acid washing tower (21) to remove alkaline gas and residual H2S; the tail gas after acid washing enters the first stage of biological treatment (23), where organic sulfur and small molecule pollutants are degraded by microorganisms, and a second stage of biological treatment (27) is added for deep biological purification; the treated tail gas is pressurized by the tail gas conveying fan (24), and after condensate separation, it is input into the condensate collection and conveying device (25), and the condensate in the condensate collection and conveying device (25) is returned to the regulating tank (11) for recycling, and the dried tail gas is transported to the tail gas co-treatment unit (3); Co-treatment of exhaust gas: The exhaust gas enters the cold side input end of the first heat exchanger (31), and the exhaust gas exchanges heat with the high temperature flue gas discharged from the cogeneration boiler (33) in the first heat exchanger (31) to raise its temperature; the heated exhaust gas enters the cogeneration boiler (33) for combustion through the flame arrester (32), thereby completely decomposing pollutants. One path of the high-temperature flue gas generated by the boiler is cooled by the hot side of the first heat exchanger (31) and then enters the flue gas treatment device (34); the other path of the high-temperature flue gas generated by the boiler is preheated by the hot side of the second heat exchanger (36) and then enters the flue gas treatment device (34); the flue gas treatment device (34) performs dust removal and denitrification to achieve emission standards.

10. The method for treating desulfurization tail gas from waste alkali solution according to claim 9, characterized in that, In the exhaust gas co-treatment, a safety interlock is also set up. The LEL lower explosion limit detector (37) monitors the concentration of combustible gas in the exhaust gas in real time. If the concentration exceeds the standard, the emergency shut-off valve group (38) is triggered to switch the exhaust gas to the backup exhaust gas treatment device.

Images