Aerosol control system in ammonia desulfurization process

Abstract

The invention provides an aerosol control system in an ammonia desulfurization process. The aerosol control system comprises a vacuum flash evaporator, a primary heat recovery device, a secondary heat recovery device and a desulfurization tower, a flue gas inlet is formed in the first-stage heat recovery device, the first-stage heat recovery device is connected with the second-stage heat recovery device and the vacuum flash evaporator, the second-stage heat recovery device is connected with the desulfurization tower through a flue gas inlet pipe, and a flow guide liquid cyclone is arranged in the flue gas inlet pipe; a washing and spraying layer, an absorption stage and a demisting unit are sequentially arranged in the desulfurization tower from bottom to top; a plurality of absorption stages are arranged, and the plurality of absorption stages are sequentially arranged in the desulfurization tower from bottom to top; a flue gas outlet is formed in the desulfurization tower, and the flue gas outlet is positioned above the demisting unit. In the desulfurization tower, the gravity type liquid uniform distributor is arranged in the absorption stage according to the liquid-gas ratio, the atomization level of absorption liquid is reduced to the minimum, and the absorption process is completed through an efficient gas-liquid catalyst.

Description

Technical Field

[0001] The present invention relates to the technical field of aerosol control in an ammonia desulfurization process, and in particular to an aerosol control system and method in an ammonia desulfurization process, and in particular to an aerosol control process method in an ammonia desulfurization process. Background Art

[0002] Ammonia desulfurization is a desulfurization process without wastewater and waste residue discharge, and is widely used in coal-fired, chemical, and petrochemical industries. However, since this process easily produces particulate matter such as ammonium sulfate and ammonium sulfite to form aerosols, it has always been a technical difficulty. Generally, in the current wet desulfurization process, high-temperature flue gas greater than 100°C enters the desulfurization tower, where it is sprayed for cooling and sprayed for absorption. In order to ensure that particulate matter in the flue gas meets the emission standards, the traditional process uses precise control of the amount of absorbent added, an increase in the liquid-to-gas ratio, additional end water washing, and even wet electrostatic demisting.

[0003] However, in fact, it is difficult to accurately control the amount of absorbent added in actual operation. The main reason is that the general control loop has control lag. When the load changes in the front section, it takes 10 to 20 seconds for the detection signal to be transmitted to the control loop. At this time, the flue gas has reached the outlet, which can easily cause the indicators to fail to meet the standards. Increasing the liquid-to-gas ratio is an idea to solve the above difficulties. In order to cope with load changes, it is necessary to ensure that the total amount of absorption liquid in the system is redundant, that is, to increase the liquid-to-gas ratio, which results in increased energy consumption. Adding end water washing has the disadvantage of high energy consumption. Adding wet electric demisting has the disadvantages of high investment, high energy consumption, and high failure rate.

[0004] There are two reasons for the generation of aerosols: the first is that hot flue gas and desulfurization slurry contact in reverse to entrain small particles and form fine particles. At the same time, there are pressure gradients, velocity gradients, temperature gradients, and concentration gradients in the flue gas, which have different effects on the formation of desulfurization slurry droplets in different particle size ranges; the second is that during the ammonia desulfurization process, the gaseous NH3 volatilized by ammonia water reacts with SO2 and water vapor in the flue gas in a heterogeneous reaction to form aerosols. When the addition ratio of NH3 to SO2 is slightly less than 2, SO2 will be completely consumed, and NH2 reacts with SO2 and water vapor to form aerosol particles, which is mainly affected by the reaction temperature and the concentration and ratio of the reactants.

[0005] The present invention is also combined with energy recovery equipment to recover the heat in the flue gas for evaporation crystallization and air preheating of the heating furnace, thereby saving energy.

[0006] The patent document with publication number CN115608147A discloses a flue gas desulfurization device, a flue gas desulfurization system and a flue gas desulfurization method, which solves the technical problems of high alkali liquid cost and secondary pollution in the prior art. The flue gas desulfurization device includes: a first channel, in which high-sulfur flue gas and desulfurization slurry contact and undergo desulfurization reaction to generate low-sulfur flue gas and a solid-liquid mixture; an injection structure for injecting desulfurization slurry into the first channel; wherein the desulfurization slurry includes desulfurization catalyst powder and a dispersant, the dispersant includes water or dilute sulfuric acid, and the desulfurization catalyst catalytically oxidizes sulfur dioxide in high-sulfur flue gas into sulfuric acid. However, the patent document still has the defect of high energy consumption. Summary of the invention

[0007] In view of the defects in the prior art, the object of the present invention is to provide an aerosol control system in an ammonia desulfurization process.

[0008] An aerosol control system in an ammonia desulfurization process provided by the present invention comprises: a vacuum flash evaporator, a primary heat recovery, a secondary heat recovery and a desulfurization tower;

[0009] The primary heat recovery is provided with a flue gas inlet, the primary heat recovery is connected with the secondary heat recovery and the vacuum flash evaporator, the secondary heat recovery is connected with the desulfurization tower through a flue gas inlet pipe, and a flow guide cyclone is provided in the flue gas inlet pipe;

[0010] The desulfurization tower is provided with a washing spray layer, an absorption stage and a demisting unit from bottom to top in sequence; the absorption stage is provided in plurality, and the plurality of absorption stages are arranged in sequence from bottom to top in the desulfurization tower;

[0011] The desulfurization tower is provided with a flue gas outlet, and the flue gas outlet is located above the demisting unit.

[0012] Preferably, the single absorption stage comprises: a liquid collector, a gas-liquid catalyst and a gravity distributor;

[0013] The liquid collector, the gas-liquid catalyst and the gravity distributor are arranged in the desulfurization tower from bottom to top;

[0014] The liquid collector diverts the rich liquid to the oxidation reactor and the rich liquid regeneration device through the rich liquid diversion device; the rich liquid regeneration device is used to transmit the regenerated rich liquid to the gravity distributor;

[0015] The oxidation reactor is connected to the ammonium sulfate solution concentration and crystallization system through an ammonium sulfate delivery pump.

[0016] Preferably, the rich liquid flow diversion device is provided with a rich liquid flow diversion control system, and the liquid flow diversion control system is used to control the diversion of the rich liquid flow diversion device;

[0017] The rich liquid regeneration device is provided with a rich liquid regeneration control system, and the rich liquid regeneration control system is used to control the regeneration of the rich liquid regeneration device.

[0018] Preferably, a first solution index analyzer is provided on the connecting pipe between the liquid collector and the rich liquid diversion device;

[0019] A second solution index analyzer is provided on the connecting pipe between the rich liquid regeneration device and the gravity distributor;

[0020] The rich solution diversion control system, the rich solution regeneration control system, the first solution index analyzer and the second solution index analyzer of all the absorption stages form a PID control logic.

[0021] Preferably, the absorption stages are set to four, namely the first absorption stage, the second absorption stage, the third absorption stage, and the fourth absorption stage;

[0022] The first absorption stage, the second absorption stage, the third absorption stage and the fourth absorption stage are arranged in the desulfurization tower in sequence from bottom to top.

[0023] Preferably, the first absorption stage comprises: a first liquid collector, a second gas-liquid catalyst and a third gravity distributor;

[0024] The first liquid collector, the second gas-liquid catalyst and the third gravity distributor are arranged from bottom to top in the desulfurization tower;

[0025] The first liquid collector diverts the rich liquid to the oxidation reactor and the first rich liquid regeneration device through the first rich liquid diverting device;

[0026] The first rich liquid regeneration device is used to transfer the regenerated rich liquid to the first gravity distributor.

[0027] Preferably, the second absorption stage comprises: a second liquid collector, a second gas-liquid catalyst and a third gravity distributor;

[0028] The second liquid collector, the second gas-liquid catalyst and the third gravity distributor are arranged from bottom to top in the desulfurization tower;

[0029] The second liquid collector diverts the rich liquid to the oxidation reactor and the second rich liquid regeneration device through the second rich liquid diverting device;

[0030] The second rich liquid regeneration device is used to transfer the regenerated rich liquid to the second gravity distributor.

[0031] Preferably, the third absorption stage comprises: a third liquid collector, a third gas-liquid catalyst and a third gravity distributor;

[0032] The third liquid collector, the third gas-liquid catalyst and the third gravity distributor are arranged from bottom to top in the desulfurization tower;

[0033] The third liquid collector diverts the rich liquid to the oxidation reactor and the third rich liquid regeneration device through the third rich liquid diverting device;

[0034] The third rich liquid regeneration device is used to transfer the regenerated rich liquid to the third gravity distributor.

[0035] Preferably, the fourth absorption stage comprises: a fourth liquid collector, a fourth gas-liquid catalyst and a fourth gravity distributor;

[0036] The fourth liquid collector, the fourth gas-liquid catalyst and the fourth gravity distributor are arranged in the desulfurization tower from bottom to top;

[0037] The fourth liquid collector diverts the rich liquid to the oxidation reactor and the fourth rich liquid regeneration device through the fourth rich liquid diverting device;

[0038] The fourth rich liquid regeneration device is used to transfer the regenerated rich liquid to the third gravity distributor.

[0039] Preferably, a liquid storage tank is provided in the desulfurization tower;

[0040] The liquid storage tank is located below the washing spray layer, and the liquid storage tank is connected to the washing spray layer through a washing circulation pump and a mixer.

[0041] Compared with the prior art, the present invention has the following beneficial effects:

[0042] 1. The present invention provides an aerosol control system in an ammonia desulfurization process. High-temperature flue gas enters a primary heat recovery device with desalted water as a cold source, produces high-temperature desalted water at 90-100°C, enters a vacuum flash evaporator, and outputs saturated steam at 80-90°C for multi-effect evaporation and crystallization of ammonium sulfate. A secondary heat recovery device is set to produce hot air at 60-70°C, which is returned to the boiler or heating furnace. The flue gas that has dropped below 70°C passes through a guide cyclone to separate the condensed acid liquid and then enters the washing section of the desulfurization tower. The washing section is provided with washing sprays in the up and down directions to wash away impurities in the flue gas. When the flue gas temperature is high, the hot flue gas and the desulfurization slurry contact in reverse to entrain small particles and form fine particles. At the same time, there are pressure gradients, velocity gradients, temperature gradients, and concentration gradients in the flue gas, which have different effects on desulfurization slurry droplets of different particle size ranges. Aerosols are easily generated in the process of cooling the flue gas and the slurry. Through the above-mentioned settings, the present invention can reduce the flue gas temperature to 60-70 degrees, and realizes the step-by-step utilization of energy through two-stage heat recovery, recovering low-temperature steam for evaporation and crystallization and recovering hot air to reduce energy consumption, and reducing the aerosols generated during the temperature exchange process when the low-temperature flue gas enters the absorption tower.

[0043] 2. The present invention sets multiple independent absorption stages according to the total amount of desulfurization. Each absorption stage includes a rich liquid diversion device and control system, a rich liquid regeneration device and control system. These two control systems and the pH and conductivity analyzers of the circulating liquid at each stage form a PID control logic. A portion of the rich liquid diverted from all absorption stages is collected and sent to the oxidation reactor for oxidation and then sent to the multi-effect evaporation system. The other portion of the rich liquid is regenerated by the rich liquid regeneration device and then circulated for desulfurization. Through the above settings, the present invention adopts an advanced detection-control scheme, which can adapt to load changes and has great operational flexibility, so that the concentration of free ammonia carried by the tail gas during the upward process is minimized, and a multi-stage absorption unit is set according to the liquid-gas ratio required by the process.

[0044] 3. The present invention only has one absorption circulation pump, and the control distribution of multiple independent absorption stages is completed through two control systems: the rich liquid diversion device and control system, and the rich liquid regeneration device and control system. Through the above arrangement, the present invention can reduce the number of circulation pumps by more than 60% and the total equipment investment by more than 20%.

[0045] 4. In the desulfurization tower of the present invention, a gravity liquid distributor is arranged in the absorption stage according to the liquid-gas ratio, so as to reduce the atomization level of the absorption liquid to the minimum, and complete the absorption process through the efficient gas-liquid catalyst. Through the above arrangement, the present invention can reduce the energy consumption of the circulation pump by more than 30%, and has low requirements for the inlet pressure of the tower, increases the operating flexibility, and makes the operating conditions of the absorption reaction more gentle, which is conducive to improving the reaction efficiency and the reaction conversion rate. In addition, the gravity distributor is not affected by the pressure, and the cross-sectional uniformity is better, which avoids uneven distribution of flue gas and absorption liquid. BRIEF DESCRIPTION OF THE DRAWINGS

[0046] Other features, objects and advantages of the present invention will become more apparent from the detailed description of non-limiting embodiments made with reference to the following drawings:

[0047] Figure 1 This is the structural block diagram of the aerosol control system in the ammonia desulfurization process.

[0048] The figure shows:

[0049] 1. Smoke inlet; 2. Primary heat recovery; 3. Secondary heat recovery; 4. Smoke inlet pipe; 5. Washing circulation pump; 6. Mixer; 7. Washing spray layer; 8. First liquid collector; 9. First gas-liquid catalyst; 10. First gravity distributor; 11. Second liquid collector; 12. Second gas-liquid catalyst; 13. Second gravity distributor; 14. Third liquid collector; 15. Third gas-liquid catalyst; 16. Third gravity distributor; 17. Fourth liquid collector; 18. Fourth gas-liquid catalyst; 19. Fourth gravity distributor; 20. Demisting Unit; 21. Flue gas outlet; 22. Absorption liquid delivery pump; 23. First rich liquid regeneration equipment; 24. First rich liquid diversion equipment; 25. Second rich liquid diversion equipment; 26. Second rich liquid regeneration equipment; 27. Third rich liquid diversion equipment; 28. Third rich liquid regeneration equipment; 29. ​​Fourth rich liquid diversion equipment; 30. Vacuum flash evaporator; 31. Ammonium sulfate delivery pump; 32. Ammonium sulfate solution concentration and crystallization system; 33. Solution index analyzer; 34. Diversion cyclone; 35. Fourth rich liquid regeneration equipment; 36. Oxidation reactor; 37. Liquid storage tank. DETAILED DESCRIPTION

[0050] The present invention is described in detail below in conjunction with specific embodiments. The following embodiments will help those skilled in the art to further understand the present invention, but are not intended to limit the present invention in any form. It should be noted that, for those of ordinary skill in the art, several changes and improvements can also be made without departing from the concept of the present invention. These all belong to the protection scope of the present invention.

[0051] Embodiment 1:

[0052] like Figure 1As shown, this embodiment provides an aerosol control system in an ammonia desulfurization process, including: a vacuum flash evaporator 30, a primary heat recovery 2, a secondary heat recovery 3 and a desulfurization tower; a flue gas inlet 1 is provided on the primary heat recovery 2, the primary heat recovery 2 is connected with the secondary heat recovery 3 and the vacuum flash evaporator 30, the secondary heat recovery 3 is connected with the desulfurization tower through a flue gas inlet pipe 4, and a flow guide cyclone 34 is provided in the flue gas inlet pipe 4; a washing spray layer 7, an absorption stage and a demisting unit 20 are sequentially arranged in the desulfurization tower from bottom to top; a plurality of absorption stages are provided, and a plurality of absorption stages are sequentially arranged in the desulfurization tower from bottom to top; a flue gas outlet 22 is provided on the desulfurization tower, and the flue gas outlet 22 is located above the demisting unit 20. A liquid storage tank 37 is provided in the desulfurization tower; the liquid storage tank 37 is located below the washing spray layer 7, and the liquid storage tank 37 is connected to the washing spray layer 7 through a washing circulation pump 5 and a mixer 6.

[0053] A single absorption stage includes: a liquid collector, a gas-liquid catalyst and a gravity distributor; the liquid collector, the gas-liquid catalyst and the gravity distributor are arranged in the desulfurization tower from bottom to top; the liquid collector diverts the rich liquid to the oxidation reactor 36 and the rich liquid regeneration device through the rich liquid diversion device; the rich liquid regeneration device is used to transfer the regenerated rich liquid to the gravity distributor; the oxidation reactor 36 is connected to the ammonium sulfate solution concentration and crystallization system 32 through the ammonium sulfate delivery pump 31. A rich liquid diversion control system is arranged on the rich liquid diversion device, and the liquid diversion control system is used to control the diversion of the rich liquid diversion device; a rich liquid regeneration control system is arranged on the rich liquid regeneration device, and the rich liquid regeneration control system is used to control the regeneration of the rich liquid regeneration device. A first solution index analyzer is arranged on the connecting pipe between the liquid collector and the rich liquid diversion device; a second solution index analyzer is arranged on the connecting pipe between the rich liquid regeneration device and the gravity distributor; the rich liquid diversion control system, the rich liquid regeneration control system, the first solution index analyzer and the second solution index analyzer of all absorption stages form a PID control logic.

[0054] There are four absorption stages, namely the first absorption stage, the second absorption stage, the third absorption stage, and the fourth absorption stage; the first absorption stage, the second absorption stage, the third absorption stage, and the fourth absorption stage are arranged in the desulfurization tower from bottom to top. The first absorption stage includes: a first liquid collector 8, a second gas-liquid catalyst 9, and a third gravity distributor 10; the first liquid collector 8, the second gas-liquid catalyst 9, and the third gravity distributor 10 are arranged in the desulfurization tower from bottom to top; the first liquid collector 8 diverts the rich liquid to the oxidation reactor 36 and the first rich liquid regeneration device 23 through the first rich liquid diversion device 24; the first rich liquid regeneration device 23 is used to transmit the regenerated rich liquid to the first gravity distributor 10. The second absorption stage includes: a second liquid collector 11, a second gas-liquid catalyst 12 and a third gravity distributor 13; the second liquid collector 11, the second gas-liquid catalyst 12 and the third gravity distributor 13 are arranged from bottom to top in the desulfurization tower; the second liquid collector 11 diverts the rich liquid to the oxidation reactor 36 and the second rich liquid regeneration device 26 through the second rich liquid diverting device 25; the second rich liquid regeneration device 26 is used to transfer the regenerated rich liquid to the second gravity distributor 13. The third absorption stage includes: a third liquid collector 14, a third gas-liquid catalyst 15 and a third gravity distributor 16; the third liquid collector 14, the third gas-liquid catalyst 15 and the third gravity distributor 16 are arranged from bottom to top in the desulfurization tower; the third liquid collector 14 diverts the rich liquid to the oxidation reactor 36 and the third rich liquid regeneration device 28 through the third rich liquid diverting device 27; the third rich liquid regeneration device 28 is used to transfer the regenerated rich liquid to the third gravity distributor 16. The fourth absorption stage includes: a fourth liquid collector 17, a fourth gas-liquid catalyst 18 and a fourth gravity distributor 19; the fourth liquid collector 17, the fourth gas-liquid catalyst 18 and the fourth gravity distributor 19 are arranged from bottom to top in the desulfurization tower; the fourth liquid collector 17 diverts the rich liquid to the oxidation reactor 36 and the fourth rich liquid regeneration equipment 37 through the fourth rich liquid diversion equipment 29; the fourth rich liquid regeneration equipment 37 is used to transfer the regenerated rich liquid to the third gravity distributor 16.

[0055] like Figure 1 As shown, A is flash steam, B is compressed air, C is ammonium sulfate solution outlet, D is absorbent replenishment, E is hot flue gas inlet, F is cold water inlet, G is hot water outlet, H is cold air inlet, and I is hot air outlet.

[0056] The heat recovery involved in this embodiment is divided into two stages. The first stage produces high-temperature desalted water at 90-100°C, which enters the vacuum flash evaporator and produces saturated steam at 80-90°C for multi-effect evaporation and crystallization of ammonium sulfate. A secondary heat recovery device is set to produce hot air at 60-70°C and return it to the boiler or heating furnace. The flue gas that drops below 70°C is separated from the condensed acid liquid by the diversion cyclone and enters the washing section of the desulfurization tower. No spray cooling is performed before entering the absorption tower. The condensed acid liquid is precipitated from the flue gas after indirect heat exchange. This embodiment focuses on cooling the flue gas to below the dew point before it enters the purification equipment. The purpose of spraying in the purification equipment is purification, not cooling. The purpose is to prevent the generation of a large temperature gradient, and the hot flue gas and the desulfurization slurry are in reverse contact to entrain small particles to form fine particles.

[0057] This embodiment relates to the field of aerosol control in the ammonia flue gas process. Ammonia flue gas is a desulfurization process that does not emit wastewater or waste residue, and is widely used in coal combustion, chemical industry, and petrochemical industry. However, since this process easily produces particulate matter such as ammonium sulfate and ammonium sulfite to form aerosols, it has always been a technical difficulty. In order to ensure that particulate matter in the exhaust gas meets the emission standards, the traditional process accurately controls the amount of absorbent added, increases the liquid-to-gas ratio, adds end water washing, and even wet electrostatic demisters. This embodiment provides a process flow for controlling the generation of aerosols, such as Figure 1 As shown. The high-temperature flue gas enters the primary heat recovery device with desalted water as the cold source, and produces high-temperature desalted water at 90-100°C, which enters the vacuum flash evaporator and outputs saturated steam at 80-90°C for ammonium sulfate multi-effect evaporation crystallization. A secondary heat recovery device is set to produce hot air at 60-70°C and return it to the boiler or heating furnace. The flue gas that drops below 70°C passes through the diversion cyclone to separate the condensed acid liquid and enter the washing section of the desulfurization tower. The washing section is provided with washing sprays in the upper and lower directions to wash away impurities in the flue gas. The present invention designs multiple independent absorption stages according to the total amount of desulfurization, and each absorption stage includes a rich liquid diversion device and a control system, a rich liquid regeneration device and a control system. These two control systems and the pH and conductivity analyzers of the circulating liquid of each stage form a PID control logic. A part of the rich liquid diverted from all absorption stages is collected and sent to the oxidation reactor for oxidation and then sent to the multi-effect evaporation system. The other part of the rich liquid is regenerated by the rich liquid regeneration equipment and then circulated for desulfurization.

[0058] This embodiment only has one absorption circulation pump, and the control distribution of multiple independent absorption stages is completed through two control systems: the rich liquid diversion device and control system, and the rich liquid regeneration device and control system. In this embodiment, a gravity liquid distributor is set in the absorption stage according to the liquid-gas ratio in the desulfurization tower to minimize the atomization level of the absorption liquid and complete the absorption process through an efficient gas-liquid catalyst.

[0059] Embodiment 2:

[0060] Those skilled in the art may understand this embodiment as a more specific description of Embodiment 1.

[0061] The present embodiment relates to the field of aerosol control in ammonia-based desulfurization, and is applicable to an absorption tower that uses ammonia as an absorbent to remove sulfur dioxide.

[0062] This embodiment provides a method for controlling aerosols in an ammonia desulfurization process, where the temperature of the flue gas entering the desulfurization device is less than 70°C. The high-temperature flue gas enters a primary heat recovery device with desalted water as a cold source, produces high-temperature desalted water at 90 to 100°C, enters a vacuum flash evaporator, and produces saturated steam at 80 to 90°C for ammonium sulfate multi-effect evaporation crystallization. A secondary heat recovery device is then set up to produce hot air at 60 to 70°C, which is returned to the boiler or heating furnace. The flue gas that drops below 70°C enters the scrubbing section of the desulfurization tower, and flue gas above 70°C is not allowed to enter the desulfurization tower.

[0063] A flow cyclone is set between the desulfurization tower and the heat recovery device to separate the condensed acid liquid. Multiple independent absorption stages are designed according to the total desulfurization amount. Each absorption stage includes rich liquid diversion equipment and control system, rich liquid regeneration equipment and control system. These two control systems and the pH and conductivity analyzers of the circulating liquid at each stage form a PID control logic.

[0064] The setting values ​​of the rich liquid diversion device and control system are the pH and conductivity of the circulating liquid, and the adjustment value is the diversion ratio control system parameter. The diversion ratio control system is realized through parameters such as flow detection, pressure detection, and change rate detection. The diversion ratio of the rich liquid diversion device is generally 0.2 to 0.5. The set pH value is generally controlled at 3 to 5.

[0065] The setting values ​​of the rich liquid regeneration equipment and control system are the pH and conductivity of the circulating liquid, and the adjustment values ​​are the adjustment parameters of the rich liquid regeneration equipment. The adjustment parameters of the rich liquid regeneration equipment are realized through parameters such as absorbent flow detection, pressure detection, and change rate detection. The set pH value is generally controlled at 3 to 7.

[0066] An absorption circulation pump is set up to complete the control distribution of multiple independent absorption stages through two control systems: rich liquid diversion equipment and control system, rich liquid regeneration equipment and control system. The number of absorption stages is calculated based on the sulfur dioxide concentration in the flue gas and the liquid-gas ratio. Each absorption stage is designed to remove 30-60% of the total sulfur dioxide.

[0067] The absorption unit is not equipped with a pressure-type liquid distributor, but a gravity-type liquid distributor to minimize the atomization level of the absorption liquid and complete the absorption process through an efficient gas-liquid catalyst. In this embodiment, the absorption area is not suitable for pressure-type liquid distributors including atomizing nozzles, centrifugal nozzles, etc.

[0068] The gravity-type liquid distributor is provided with one or more liquid inlets according to different tower diameters, and one or more levels of distribution are provided. The deviation rate of the number of liquid drop points per square meter is less than 10%, thereby ensuring uniform distribution.

[0069] The gas-liquid contact completes the absorption process through a highly efficient gas-liquid catalyst. When the absorption reaction occurs on this catalyst, it is carried out under liquid phase homogeneous conditions.

[0070] The ammonium sulfate solution discharged from the desulfurization tower does not contain solid ammonium sulfate crystals, and solid ammonium sulfate is produced through a multiple-effect evaporation crystallization process. The high-temperature water recovered from the primary heat recovery of flue gas is high-temperature desalted water with a temperature of 90 to 100°C. After passing through a vacuum flash evaporator, saturated steam at 80 to 90°C is flashed out for multiple-effect evaporation crystallization of ammonium sulfate. The secondary heat recovery device produces hot air at 60 to 70°C and returns it to the boiler or heating furnace. The energy-saving effect is significant.

[0071] Embodiment 3:

[0072] Those skilled in the art may understand this embodiment as a more specific description of Embodiment 1.

[0073] This embodiment provides a process flow for controlling aerosol generation, such as Figure 1 As shown. The high-temperature flue gas enters the primary heat recovery device 2 with desalted water as the cold source, produces high-temperature desalted water at 90-100°C, enters the vacuum flash evaporator 30, and outputs saturated steam at 80-90°C for ammonium sulfate multi-effect evaporation crystallization 32. Since the multi-effect evaporation is carried out under a negative pressure of -70-80 kPag, the generated steam can be used for heating the circulating material.

[0074] In this embodiment, a secondary heat recovery device 3 is provided to produce hot air at 60-70° C., which is returned to the boiler or heating furnace, thereby saving energy for air preheating and fuel gas.

[0075] In this embodiment, the flue gas needs to be cooled to below 70°C, and then separated from the condensed acid by the diversion cyclone 34 before entering the scrubbing section of the desulfurization tower. The scrubbing section is provided with scrubbing sprays 7 in the up and down directions to wash away impurities in the flue gas. The low-temperature flue gas contacts the scrubbing liquid, which greatly reduces the amount of fine particles formed by the reverse contact between the flue gas and the desulfurization slurry and the entrainment of small particles.

[0076] This embodiment designs multiple independent absorption stages according to the total amount of desulfurization. Each absorption stage includes a rich liquid diversion device and control system, a rich liquid regeneration device and control system. These two control systems and the pH and conductivity analyzers of the circulating liquid at each stage form a PID control logic. A portion of the rich liquid diverted from all absorption stages is collected and sent to the oxidation reactor for oxidation and then sent to the multi-effect evaporation system. The other portion of the rich liquid is regenerated by the rich liquid regeneration device and then circulated for desulfurization. The PID control logic formed by the advanced rich liquid diversion device and control system and the rich liquid regeneration device and control system can avoid the heterogeneous reaction between gaseous NH3 and SO2 in the flue gas to generate aerosol.

[0077] In this embodiment, only one absorption circulation pump is provided, and control distribution of multiple independent absorption stages is accomplished through two control systems, namely, a rich liquid diversion device and control system and a rich liquid regeneration device and control system.

[0078] In this embodiment, a gravity liquid distributor is set in the absorption stage according to the liquid-gas ratio in the desulfurization tower to minimize the atomization level of the absorption liquid and complete the absorption process through an efficient gas-liquid catalyst. The gravity liquid distributor is set with one or more liquid inlets according to the different tower diameters, and one or more levels of distribution are set. The deviation rate of the number of liquid drop points per square meter is less than 10%, ensuring uniform distribution. The gas-liquid contact completes the absorption process through an efficient gas-liquid catalyst. When the absorption reaction occurs on this catalyst, it is carried out under liquid phase homogeneity conditions.

[0079] In the desulfurization tower of the present invention, a gravity-type liquid distributor is arranged in the absorption stage according to the liquid-gas ratio to reduce the atomization level of the absorption liquid to the minimum, and the absorption process is completed through a highly efficient gas-liquid catalyst.

[0080] In the description of the present application, it should be understood that the terms "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", etc., indicating orientations or positional relationships, are based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present application.

[0081] The above describes the specific embodiments of the present invention. It should be understood that the present invention is not limited to the above specific embodiments, and those skilled in the art can make various changes or modifications within the scope of the claims, which does not affect the essence of the present invention. In the absence of conflict, the embodiments of the present application and the features in the embodiments can be combined with each other arbitrarily.

Claims

1. An aerosol control system in an ammonia desulfurization process, characterized in that: include: A vacuum flash evaporator (30), a primary heat recovery (2), a secondary heat recovery (3) and a desulfurization tower; The primary heat recovery (2) is provided with a flue gas inlet (1), the primary heat recovery (2) is connected to the secondary heat recovery (3) and the vacuum flash evaporator (30), the secondary heat recovery (3) is connected to the desulfurization tower via a flue gas inlet pipe (4), and a flow guide cyclone (34) is provided in the flue gas inlet pipe (4); The desulfurization tower is provided with a washing spray layer (7), an absorption stage and a demisting unit (20) in order from bottom to top; the absorption stage is provided in plurality, and the plurality of absorption stages are arranged in order from bottom to top in the desulfurization tower; The desulfurization tower is provided with a flue gas outlet (22), and the flue gas outlet (22) is located above the demisting unit (20).

2. The aerosol control system in the ammonia desulfurization process according to claim 1, characterized in that: The single absorption stage comprises: a liquid collector, a gas-liquid catalyst and a gravity distributor; The liquid collector, the gas-liquid catalyst and the gravity distributor are arranged in the desulfurization tower from bottom to top; The liquid collector diverts the rich liquid to the oxidation reactor (36) and the rich liquid regeneration device through the rich liquid diversion device; the rich liquid regeneration device is used to transmit the regenerated rich liquid to the gravity distributor; The oxidation reactor (36) is connected to the ammonium sulfate solution concentration and crystallization system (32) via an ammonium sulfate delivery pump (31).

3. The aerosol control system in the ammonia desulfurization process according to claim 2, characterized in that: The rich liquid flow diversion device is provided with a rich liquid flow diversion control system, and the liquid flow diversion control system is used to control the diversion of the rich liquid flow diversion device; The rich liquid regeneration device is provided with a rich liquid regeneration control system, and the rich liquid regeneration control system is used to control the regeneration of the rich liquid regeneration device.

4. The aerosol control system in the ammonia desulfurization process according to claim 3, characterized in that: A first solution index analyzer is provided on the connecting pipe between the liquid collector and the rich liquid diversion device; A second solution index analyzer is provided on the connecting pipe between the rich liquid regeneration device and the gravity distributor; The rich solution diversion control system, the rich solution regeneration control system, the first solution index analyzer and the second solution index analyzer of all the absorption stages form a PID control logic.

5. The aerosol control system in the ammonia desulfurization process according to claim 4, characterized in that: The absorption stages are set to four, namely the first absorption stage, the second absorption stage, the third absorption stage, and the fourth absorption stage; The first absorption stage, the second absorption stage, the third absorption stage and the fourth absorption stage are arranged in the desulfurization tower in sequence from bottom to top.

6. The aerosol control system in the ammonia desulfurization process according to claim 5, characterized in that: The first absorption stage comprises: a first liquid collector (8), a second gas-liquid catalyst (9) and a third gravity distributor (10); The first liquid collector (8), the second gas-liquid catalyst (9) and the third gravity distributor (10) are arranged in the desulfurization tower from bottom to top; The first liquid collector (8) diverts the rich liquid to the oxidation reactor (36) and the first rich liquid regeneration device (23) via the first rich liquid diverting device (24); The first rich liquid regeneration device (23) is used to transfer the regenerated rich liquid to the first gravity distributor (10).

7. The aerosol control system in the ammonia desulfurization process according to claim 6, characterized in that: The second absorption stage comprises: a second liquid collector (11), a second gas-liquid catalyst (12) and a third gravity distributor (13); The second liquid collector (11), the second gas-liquid catalyst (12) and the third gravity distributor (13) are arranged in the desulfurization tower from bottom to top; The second liquid collector (11) distributes the rich liquid to the oxidation reactor (36) and the second rich liquid regeneration device (26) through the second rich liquid distribution device (25); The second rich liquid regeneration device (26) is used to transfer the regenerated rich liquid to the second gravity distributor (13).

8. The aerosol control system in the ammonia desulfurization process according to claim 7, characterized in that: The third absorption stage comprises: a third liquid collector (14), a third gas-liquid catalyst (15) and a third gravity distributor (16); The third liquid collector (14), the third gas-liquid catalyst (15) and the third gravity distributor (16) are arranged in the desulfurization tower from bottom to top; The third liquid collector (14) diverts the rich liquid to the oxidation reactor (36) and the third rich liquid regeneration device (28) via the third rich liquid diverting device (27); The third rich liquid regeneration device (28) is used to transfer the regenerated rich liquid to the third gravity distributor (16).

9. The aerosol control system in the ammonia desulfurization process according to claim 8, characterized in that: The fourth absorption stage comprises: a fourth liquid collector (17), a fourth gas-liquid catalyst (18) and a fourth gravity distributor (19); The fourth liquid collector (17), the fourth gas-liquid catalyst (18) and the fourth gravity distributor (19) are arranged in the desulfurization tower from bottom to top; The fourth liquid collector (17) diverts the rich liquid to the oxidation reactor (36) and the fourth rich liquid regeneration device (37) via the fourth rich liquid diverting device (29); The fourth rich liquid regeneration device (37) is used to transfer the regenerated rich liquid to the third gravity distributor (16).

10. The aerosol control system in the ammonia desulfurization process according to claim 1, characterized in that: A liquid storage tank (37) is provided in the desulfurization tower; The liquid storage tank (37) is located below the washing spray layer (7), and the liquid storage tank (37) is connected to the washing spray layer (7) via a washing circulation pump (5) and a mixer (6).

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