A system and method for desulfurization and desorption of sulfur dioxide by multi-stage desulfurization liquid-rich air conditioning

Abstract

This invention discloses a system and method for desorbing sulfur dioxide in a multi-stage desulfurization system using a rich liquid cavitation system. The system includes multiple desorption units, each divided into upper and lower chambers by a heating surface. The upper chamber is the desorption chamber, and the lower chamber is the steam heating chamber. The exhaust port of the desorption chamber in each preceding desorption unit is connected to the steam inlet of the steam heating chamber in the following stage. The condensate outlet of the steam heating chamber in each following stage is connected to the desorbed liquid inlet of the desorption chamber in the preceding stage. The method also includes multiple desorption units, utilizing the steam generated during cavitation in the desorption chamber of the preceding stage as the heating steam for the steam heating chamber of the following stage, thus desorbing SO2 from the desorption chamber and making the thermal energy of the desorbed steam from the preceding stage the heat source for the subsequent stage.

Description

Technical Field

[0001] This invention belongs to the fields of energy and power engineering and environmental engineering, and specifically relates to a system and method for desulfurization and desorption of sulfur dioxide by multi-stage desulfurization liquid-rich air. Background Technology

[0002] Currently, the combustion of sulfur compounds associated with coal produces SO2, which causes air pollution and is one of the factors contributing to acid rain and smog. Furthermore, my country is a country with scarce available sulfur resources. Therefore, advanced methods for the efficient removal and recycling of SO2 from coal-fired flue gas have been a subject of ongoing research and exploration.

[0003] The alkaline aluminum sulfate desorption desulfurization method is theoretically a desulfurization technology with high efficiency in removing and desorbing SO2. After desorbing SO2 in the rich desulfurization solution, the regenerated alkaline aluminum sulfate can be recycled. The desorption product—high-purity SO2—can be sold as a product or used to manufacture sulfuric acid and sulfur. It has the dual value of controlling sulfur dioxide pollution and utilizing coal sulfur resources.

[0004] The currently disclosed technology uses alkaline aluminum sulfate solution to remove SO2. There are two main methods for desorbing SO2 from the rich desulfurization solution: One is a steam stripping method using water vapor to heat the rich desulfurization solution to 100℃ for SO2 desorption. Experiments conducted by the Shenyang Chemical Research Institute in 1954 showed that when the desorption rate is close to 100%, desorbing 1 ton of SO2 consumes 6.7 tons of low-pressure steam. The other is a method using alkaline aluminum sulfate desulfurization solution for SO2 desorption via air evaporation, as disclosed in patents (ZL201821778513.5 and CN201811276655.6). Experiments by the applicant of this invention showed that when the desorption rate is close to 94%, at 55℃, air evaporation of 1 ton of SO2 generates approximately 6.7 tons of water vapor (heat consumption of approximately 15.856 × 10⁻⁶). 6 The process requires a large heat source (kilojoules), resulting in high heat consumption and significant investment in conveying equipment. Furthermore, for every ton of SO2 desorbed, at least 6.7 tons of water vapor are produced, forming a mixed gas. This requires condensing 6.7 tons of water vapor to obtain 1 ton of SO2, necessitating large-scale condensation equipment and excessively high investment. This increased cost of SO2 desorption is one of the reasons why the alkaline aluminum sulfate desorption desulfurization method has not been widely adopted.

[0005] In view of this, the present invention is hereby proposed. Summary of the Invention

[0006] To address the aforementioned problems, the purpose of this invention is to provide a system and method for multi-stage desulfurization and desorption of sulfur dioxide by liquid-rich air, thereby solving the problems of high heat consumption, large scale of heat transport equipment and steam condensation equipment, and high investment in alkaline aluminum sulfate desorption desulfurization method for SO2 desorption.

[0007] To achieve the above objectives, the present invention provides a multi-stage desulfurization system for desorbing sulfur dioxide in a liquid-rich cavitation system, comprising a multi-stage cavitation desorption unit, wherein each stage of the cavitation desorption unit is divided into upper and lower chambers by a heating surface, the upper chamber being the cavitation desorption chamber and the lower chamber being the steam heating chamber.

[0008] The exhaust port of the desorption chamber of each pre-stage desorption unit is connected to the steam inlet of the steam heating chamber of the subsequent stage desorption unit via a pipeline.

[0009] Preferably, the condensate outlet of the steam heating chamber of each subsequent air desorption unit is connected to the desorbent inlet of the air desorption chamber of the preceding air desorption unit via a pipeline. The gas outlets of the steam heating chambers from the second-stage air desorption unit to the final-stage air desorption unit are connected to the SO2 utilization process via a vacuum system. A vacuum system is provided at the gas outlet of the steam heating chamber of the first-stage air desorption unit, and the condensate outlet of the steam heating chamber of the first-stage air desorption unit is connected to the heat source recovery system via a condensate pump.

[0010] Furthermore, the steam inlet of the steam heating chamber of the primary air desorption unit is connected to a parallel steam jet pump and a bypass valve, and the steam enters the steam heating chamber through the steam jet pump or the bypass valve.

[0011] Furthermore, the exhaust port of the desorption chamber of the final stage air desorption unit is connected to a heat exchanger and a direct air-cooling system. The gas-side inlet of the heat exchanger is connected to the exhaust port of the desorption chamber of the final stage air desorption unit, and the gas-side outlet of the heat exchanger is connected to the direct air-cooling system.

[0012] Furthermore, the system also includes a desulfurization rich liquid header and a regenerated liquid header. The desulfurization rich liquid header supplies desulfurization rich liquid to the desorption chamber of each stage of air desorption unit. The regenerated solution after desorption of SO2 by the desorption chamber of each stage of air desorption unit is output to the regenerated liquid header. The water-side inlet of the heat exchanger is connected to the desulfurization system, and the water-side outlet of the heat exchanger is connected to the desulfurization rich liquid header. The condensate outlets of the heat exchanger and the direct air-cooling system are connected to the desulfurization rich liquid header. The vacuum system of the direct air-cooling system is connected to the SO2 utilization process flow.

[0013] Preferably, the cavitation temperature of the desulfurized rich liquid in the preceding cavitation desorption unit is higher than that in the following cavitation desorption unit, and the steam temperature in the steam heating chamber of the same cavitation desorption unit is higher than that in the desulfurized rich liquid in the cavitation desorption chamber.

[0014] The present invention also provides a method for desorbing sulfur dioxide in a multi-stage desulfurization liquid-rich cavitation system, comprising a multi-stage cavitation desorption unit, wherein the steam generated during cavitation in the desorption chamber of the preceding stage cavitation desorption unit is used as the heating steam for the steam heating chamber of the following stage cavitation desorption unit to desorb SO2 in that stage cavitation desorption chamber, so that the heat energy of the desorption steam in the preceding stage becomes the heat source for desorption in the following stage cavitation unit.

[0015] Preferably, industrial exhaust steam is used as a heat source, and the temperature of the industrial exhaust steam is not higher than the desulfurization-rich liquid cavitation temperature of the first-stage cavitation desorption unit, including the following steps:

[0016] (1) When the bypass valve is closed, the industrial exhaust steam exchanges energy with the working steam and is heated when it passes through the steam jet pump. The temperature of the heated industrial exhaust steam is higher than the desorption temperature of sulfur dioxide desorbed by the primary air desorption unit.

[0017] (2) The heated industrial exhaust steam enters the steam heating chamber through the steam inlet of the first-stage cavitation desorption unit. The desulfurized rich liquid in the first-stage cavitation desorption unit undergoes cavitation desorption, and the regeneration solution enters the regeneration liquid header. The SO2 and water vapor mixture generated by desorption enters the steam heating chamber of the next stage cavitation desorption unit through the exhaust port of the first-stage cavitation desorption unit. The non-condensable gas in the steam heating chamber of the first-stage cavitation desorption unit is discharged through the gas outlet via the vacuum system. The condensate in the steam heating chamber of the first-stage cavitation desorption unit is transported to the heat source regeneration system through the condensate outlet by the condensate pump.

[0018] (3) The desulfurized rich liquid in the desorption chamber of the next stage desorption unit undergoes desorption and cavitation. The regenerated solution enters the regenerated liquid header. The SO2 and water vapor mixture generated by desorption enters the steam heating chamber of the next two stages of desorption units through the exhaust port of the desorption chamber of this stage. The water condensed in the steam heating chamber of the next stage desorption unit flows to the desorption chamber of the first stage desorption unit through the condensate outlet. The SO2 gas in the steam heating chamber of the next stage desorption unit is sent to the SO2 utilization process through the vacuum system via the gas outlet.

[0019] Step (3) is repeated until the desulfurized rich liquid in the desorption chamber of the final stage desorption unit undergoes desorption.

[0020] (5) In the desulfurization rich liquid of the desulfurization desorption chamber of the final stage desulfurization desorption unit, desulfurization occurs. The regenerated solution enters the regenerated liquid header. The water vapor and SO2 mixed gas generated by desorption first enter the gas side of the heat exchanger and exchange heat with the desulfurization rich liquid from the desulfurization system on the water side of the heat exchanger. Some of the steam condenses. The uncondensed steam and SO2 enter the direct air cooling system. The water vapor condenses into condensate and is separated from the SO2 gas. The condensate enters the desulfurization rich liquid header, and the SO2 is sent to the utilization process. The condensate from the heat exchanger enters the desulfurization rich liquid header. The desulfurization rich liquid after the water side of the heat exchanger has been heated by heat exchange enters the desulfurization rich liquid header.

[0021] Preferably, industrial exhaust steam is used as a heat source, and the temperature of the industrial exhaust steam is higher than the cavitation temperature of the desulfurization-rich liquid in the first-stage system, including the following steps:

[0022] (1) Open the bypass valve, and the industrial exhaust steam enters the steam heating chamber through the bypass valve and the steam inlet of the primary air desorption unit;

[0023] (2) The desulfurized rich liquid in the desorption chamber of the first-stage desorption unit undergoes desorption and cavitation. The regenerated solution enters the regenerated liquid header. The SO2 and water vapor mixture generated by desorption enters the steam heating chamber of the next stage desorption unit through the exhaust port of the desorption chamber of this stage. The non-condensable gas in the steam heating chamber of the first-stage desorption unit is discharged through the gas outlet via the vacuum system. The condensate in the steam heating chamber of the first-stage desorption unit is transported to the heat source regeneration system through the condensate outlet by the condensate pump.

[0024] (3) The desulfurized rich liquid in the desorption chamber of the next stage desorption unit undergoes desorption and cavitation. The regenerated solution enters the regenerated liquid header. The SO2 and water vapor mixture generated by desorption enters the steam heating chamber of the next two stages of desorption units through the exhaust port of the desorption chamber of this stage. The water condensed in the steam heating chamber of the next stage desorption unit flows to the desorption chamber of the first stage desorption unit through the condensate outlet. The SO2 gas in the steam heating chamber of the next stage desorption unit is sent to the SO2 utilization process through the vacuum system via the gas outlet.

[0025] Step (3) is repeated until the desulfurized rich liquid in the desorption chamber of the final stage desorption unit undergoes desorption.

[0026] (4) In the desulfurization rich liquid of the desulfurization desorption chamber of the final stage desulfurization desorption unit, desulfurization occurs. The regenerated solution enters the regenerated liquid header. The water vapor and SO2 mixed gas generated by desorption first enter the gas side of the heat exchanger and exchange heat with the desulfurization rich liquid from the desulfurization system on the water side of the heat exchanger. Some of the steam condenses. The uncondensed steam and SO2 enter the direct air cooling system. The water vapor condenses into condensate and is separated from the SO2 gas. The condensate enters the desulfurization rich liquid header, and the SO2 is sent to the utilization process. The condensate from the heat exchanger enters the desulfurization rich liquid header. The desulfurization rich liquid after the water side of the heat exchanger has been heated by heat exchange enters the desulfurization rich liquid header.

[0027] Furthermore, it also includes the following steps:

[0028] (0) The desulfurization rich liquid is sent into the desorption chamber of each stage of the air desorption unit and the regenerated liquid manifold to reach the set liquid level value.

[0029] The air desorption chambers and steam heating chambers of each air desorption unit, as well as the heat exchangers, direct air cooling system, desulfurization rich liquid header, regeneration liquid header and connecting pipelines, are vented to their respective required pressure settings.

[0030] The present invention provides a system and method for multi-stage desulfurization and desorption of sulfur dioxide by liquid-rich air conditioning, which has the following beneficial effects:

[0031] 1. Industrial production exhaust contains a large amount of latent heat of vaporization, which is discharged into the natural environment as waste heat. This invention utilizes this waste heat to provide heat for desorption of SO2 by air purifiers. This not only solves the problem of the huge amount of heat of vaporization required for desorption of SO2 by air purifiers, but also allows the latent heat of exhaust steam to be reused once, thus treating waste with waste and reducing the cost of SO2 desorption.

[0032] 2. The condensate after the steam heating chamber is heated is not contaminated and can be returned to the heat source regeneration system for reuse;

[0033] 3. The SO2 and water vapor mixture generated by the desorption of the previous stage air desorption unit enters the steam heating chamber of the next stage air desorption unit to provide the heat required for the desorption of the next stage air desorption unit. The latent heat of vaporization is reused multiple times, and the heat required from the heat source is significantly reduced. Compared with the heat required from the heat source of a single stage air desorption unit, the heat required by the N-stage air desorption unit is approximately 1 / N of that of the single stage air desorption unit.

[0034] 4. The steam condensation amount of the last stage air desorption unit in the N-stage air desorption unit of the direct air cooling system is less than 1 / N of that of a single stage, which significantly reduces the steam condensation amount of the direct air cooling system.

[0035] 5. The temperature of the circulating desulfurization liquid in the desulfurization system is lower than the temperature of the steam and SO2 mixture generated by the final stage air-cooling desorption unit. The heat exchanger utilizes this temperature difference to achieve the beneficial effects of both increasing the temperature of the desulfurization rich liquid entering the air-cooling desorption chamber and reducing the condensation load of the direct air-cooling system. Furthermore, the design of the multi-stage air-cooling desorption unit will significantly reduce the steam condensation load of the direct air-cooling system.

[0036] 6. This significantly reduces the size of heat source equipment and direct air cooling systems, effectively lowering investment in SO2 desorption equipment and ultimately significantly reducing SO2 desorption costs. Attached Figure Description

[0037] Figure 1 This is a schematic diagram of the structure of the three-stage desulfurization system for desorbing sulfur dioxide using liquid air in Examples 1 and 2.

[0038] In the attached diagram: 1. Heating surface; 2. Air desorption chamber; 3. Steam heating chamber; 4. Steam inlet; 5. Condensate outlet; 6. Gas outlet; 7. Vacuum system; 8. Desorption liquid inlet; 9. Desorption liquid outlet; 10. Exhaust port; 11. Steam jet pump; 12. Bypass valve; 13. Heat exchanger; 14. Direct air cooling system; 15. Desulfurization rich liquid header; 16. Throttling valve; 17. Regenerated liquid header; 18. Regenerated liquid pump; 19. Condensate pump; 20. Desulfurization system. Detailed Implementation

[0039] To enable those skilled in the art to better understand the present invention, the present invention will be further described in detail below with reference to specific embodiments.

[0040] This patent discloses a multi-stage desulfurization system for desorbing sulfur dioxide using a rich liquid air purifier. The system is an N-stage desulfurization system for desorbing SO2 using an alkaline aluminum sulfate desulfurization system. It consists of a first-stage desorption unit, a final-stage desorption unit, and N-2 intermediate-stage desorption units. By repeatedly and continuously using steam condensation to release latent heat, it solves the problems of high heat consumption, large scale of heat transfer and steam condensation equipment, and excessive investment associated with SO2 desorption in alkaline aluminum sulfate desulfurization systems, effectively reducing the cost of SO2 desorption.

[0041] Each level of air desorption unit is divided into upper and lower chambers by a heating surface 1. The upper chamber is the air desorption chamber 2, and the lower chamber is the steam heating chamber 3. The steam heating chamber 3 of the first-stage air desorption unit, which uses industrial production exhaust steam as a heat source, and the other levels of air desorption units are all located at the lower part of the heating surface 1. The steam heating chamber 3 is equipped with a steam inlet 4, a condensate outlet 5 at the lower part of the steam heating chamber 3, and a gas outlet 6 and a vacuum system 7 at the upper part of the steam heating chamber 3. The air desorption chamber 2 of all levels of air desorption units is located at the upper part of the heating surface 1. The air desorption chamber 2 is equipped with a desorption liquid inlet 8, a desorption liquid outlet 9 at the lower part of the air desorption chamber 2, and an exhaust port 10 at the upper part of the air desorption chamber 2.

[0042] The heating surface 1 is used to transfer the heat released by the condensation of water vapor in the steam heating chamber 3 to the desorbed liquid in the cavitation desorption chamber 2. The upper surface of the heating surface 1 is the bottom of the cavitation desorption chamber 2. The cavitation temperature of the alkaline aluminum sulfate desulfurization rich liquid in the cavitation desorption chamber 2 of the last-stage cavitation desorption unit must be at least higher than 50°C, and the cavitation temperature of the previous stage cavitation desorption unit must be higher than that of the next stage to form the necessary heat transfer temperature difference. The lower surface of the heating surface 1 is the top of the steam heating chamber 3. The steam temperature in the steam heating chamber 3 must be higher than the cavitation temperature set for the desorbed desulfurization rich liquid in the cavitation desorption chamber 2 of this stage to form the necessary heat transfer temperature difference.

[0043] The steam inlet 4 of the steam heating chamber of the first-stage desorption unit, which uses industrial exhaust steam as a heat source, is connected to a parallel steam jet pump 11 and a bypass valve 12. Industrial exhaust steam enters the steam inlet 4 through the steam jet pump 11 or the bypass valve 12. The steam jet pump 11 heats the turbine exhaust steam (which is below the required temperature) to the required temperature with high-pressure steam and outputs it to the steam heating chamber 3 of the first-stage desorption unit. If the turbine exhaust steam temperature meets the required temperature range, or if there is extraction steam that meets the required temperature range, it can be directly delivered to the steam heating chamber 3 of the first-stage desorption unit through the bypass valve 12 and the steam inlet 4. The condensate outlet 5 of the first-stage desorption unit is also connected to a condensate pump 19. The exhaust port 10 of the desorption chamber of the last-stage desorption unit is sequentially connected to a heat exchanger 13 and a direct air-cooling system 14, wherein the heat exchanger 13 and the direct air-cooling system 14 are positioned higher than the desulfurization rich liquid header 15. The water side of heat exchanger 13 receives the lower-temperature desulfurization rich liquid from desulfurization system 20. The gas side of heat exchanger 13 receives a mixture of water vapor and SO2 from the exhaust port 10 of the desulfurization chamber of the final stage desulfurization unit. After surface heat exchange, the heated desulfurization rich liquid and condensate are output to the desulfurization rich liquid header 15, while the uncondensed water vapor and SO2 mixture are output to the direct air-cooling system 14. The direct air-cooling system 14 includes a steam distribution system, radiators, a condensate system, and a vacuum system. The direct air-cooling system 14 receives the water vapor and SO2 mixture from the heat exchanger, condenses the water vapor and separates it from the SO2 through surface heat exchange with ambient air, outputs the SO2 to the SO2 utilization process through the vacuum system, and collects the condensate in the condensate system before outputting it to the desulfurization rich liquid header 15.

[0044] Except for the primary cavitation desorption unit, the condensate outlet 5 of the steam heating chamber 3 of each stage of the cavitation desorption unit is higher than the desorbent inlet 8 of the preceding stage's cavitation desorption chamber 2. The steam heating chamber 3 of the primary cavitation desorption unit receives water vapor, such as turbine exhaust steam, extraction steam, or exhaust steam heated to the required temperature by the steam jet pump 11, through the steam inlet 4. The steam heating chambers 3 of the remaining stages of the cavitation desorption unit receive a mixture of water vapor and SO2 gas output from the preceding stage's cavitation desorption chamber 2 through the steam inlet 4. The condensate in the steam heating chamber 3 of the primary cavitation desorption unit is transported to the heat source regeneration system by the condensate pump 19 through the condensate outlet 5. The condensate in the steam heating chambers 3 of the remaining stages of the cavitation desorption unit flows by gravity to the preceding stage's cavitation desorption chamber 2 after passing through the condensate outlet 5. The non-condensable gas in the steam heating chamber 3 of the first-stage cavitation desorption unit is discharged through the gas outlet 6 by the vacuum system 7, and the SO2 gas in the steam heating chamber 3 of the remaining stages of cavitation desorption units is sent to the SO2 utilization process through the gas outlet 6 by the vacuum system 7.

[0045] Each air desorption chamber 2 of the air desorption unit receives the liquid to be desorbed from the desulfurization rich liquid header 15 through its own desorption liquid inlet 8, and its flow rate is regulated and controlled by the throttle valve 16 installed on the pipeline of the desorption liquid inlet 8.

[0046] The regenerated alkaline aluminum sulfate solution after desorbing SO2 in the desorption chamber 2 of each air-conditioning desorption unit is output to the regenerated liquid header 17 through its respective desorption liquid outlet 9. An overflow weir is provided at the desorption liquid outlet 9 to control the liquid level in the air-conditioning desorption chamber 2. The liquid level in the regenerated liquid header 17 is lower than the top height of the overflow weir of the first-stage desorption liquid outlet 9. The regenerated liquid header 17 and the first-stage air-conditioning desorption chamber are connected to maintain the same internal pressure, forming a free overflow from the overflow weir. The liquid flowing out of the overflow weirs of other stages is introduced into the regenerated liquid header 17 below the liquid surface through the downcomer pipe, forming a submerged outflow, which blocks the airflow channels between the desorption chambers 2 of each stage, providing conditions for the differential control of the temperature and pressure setpoints of the desorption chambers 2 of each stage. A regenerated liquid pump 18 is provided on the outlet pipe of the regenerated liquid header 17 to transport the regenerated alkaline aluminum sulfate solution to the desulfurization system or the sulfate neutralization system.

[0047] Example 1

[0048] Taking a three-stage desulfurization system for desorbing sulfur dioxide using rich liquid cavitation as an example, the cavitation desorption temperature of the alkaline aluminum sulfate desulfurization rich liquid in the desorption chamber 2 of the final stage desulfurization unit is set to 55℃. The inter-stage temperature difference between the desulfurization rich liquid cavitation desorption temperatures of adjacent stages is set to 5℃. The temperature difference between the cavitation temperature of the rich liquid in the same stage and the temperature of the steam or steam / SO2 mixture in the steam heating chamber 3 is set to 5℃. The exhaust steam from the turbine operating at a back pressure of 12.34 kPa is used as the heat source for supplying heat for SO2 desorption. The turbine exhaust steam temperature is approximately 50℃, requiring a steam jet pump 11 to heat the 50℃ exhaust steam to 70℃ using high-pressure steam. The depth of the desorbed liquid in each stage desorption chamber 2 is set to 300mm, and the flow velocity of the desorbed liquid from the desorbed liquid inlet 8 to the desorbed liquid outlet 9 is set to 0.05m / s.

[0049] like Figure 1 As shown, the three-stage desulfurization system for desorbing sulfur dioxide using liquid-rich air conditioning consists of three parts: a first-stage air conditioning desorption unit, a second-stage air conditioning desorption unit, and a final-stage air conditioning desorption unit. The latter stage air conditioning desorption unit is located above the former stage and is arranged in a three-dimensional manner.

[0050] In the steam heating chambers 3 of the first-stage desorption unit, the second-stage desorption unit, and the final-stage desorption unit, the lower part contains steam condensate, and the upper part contains water vapor or a mixture of water vapor and SO2. The steam heating chamber 3 of the first-stage desorption unit receives steam from the turbine exhaust gas (heated from 50°C to 70°C by the steam jet pump 11) via the steam inlet 4. The steam heating chamber 3 of the second-stage desorption unit receives a mixture of 65°C water vapor and SO2 from the first-stage desorption unit via the steam inlet 4. The steam heating chamber 3 of the final-stage desorption unit receives a mixture of 60°C water vapor and SO2 from the second-stage desorption unit via the steam inlet 4. The condensate from the steam heating chamber 3 of the first-stage desorption unit is pumped to the heat source regeneration system by the condensate pump 19 after exiting through the condensate outlet 5. The condensate from the remaining desorption units flows by gravity from the condensate outlet 5 to the desorption chamber 2 of the preceding stage desorption unit. The non-condensable gas in the steam heating chamber 3 of the first-stage desorption unit is discharged to the vacuum system 7 via gas outlet 6. The SO2 gas in the steam heating chamber 5 of the second-stage and final-stage desorption units is discharged to the vacuum system 7 via gas outlet 6 and then sent to the SO2 utilization process. The separation of SO2 and water vapor in the final-stage desorption unit is carried out in the direct air-cooling system 14. The SO2 gas obtained after condensing the water vapor is sent to the SO2 utilization process by the vacuum system of the direct air-cooling system 14.

[0051] The heating surface 1 is used to transfer the heat released by the condensation of water vapor in the steam heating chamber 3 to the desorbed liquid in the cavitation desorption chamber 2. The upper surface of the heating surface 1 is the bottom of the cavitation desorption chamber 2. The vacuum system of the direct air cooling system 14 and the vacuum systems 7 of the last stage and the second stage control the pressure values ​​in the cavitation desorption chamber 2 of the last stage cavitation desorption unit, the second stage cavitation desorption unit, and the first stage cavitation desorption unit, respectively. This ensures that the cavitation desorption temperature of the alkaline aluminum sulfate desulfurization rich liquid in the cavitation desorption chamber 2 of the last stage cavitation desorption unit, the second stage cavitation desorption unit, and the first stage cavitation desorption unit reaches the set 55℃, 60℃, and 65℃, respectively, forming a heat transfer temperature difference of 5℃ between adjacent stages. The lower surface of the heating surface 1 forms the top of the steam heating chamber 3. The steam temperatures in the steam heating chambers 3 of the final stage desorption unit, the second stage desorption unit, and the first stage desorption unit are set to 60℃, 65℃, and 70℃, respectively, forming a 5℃ heat transfer temperature difference with the desulfurized rich liquid desorption temperature set in the desorption chamber 2 of the same stage. The steam jet pump 11 is used to heat the turbine exhaust steam at 50℃ to the required 70℃ using high-pressure steam and output it to the steam heating chamber 3 of the first stage desorption unit. In this operating condition, the bypass valve is closed.

[0052] The heat exchanger 13 is arranged above the top of the desulfurization rich liquid header 15. It is used to receive the desulfurization rich liquid with a temperature of less than 45°C from the desulfurization system 20 and the 55°C water vapor and SO2 mixture from the exhaust port 10 of the air desorption chamber 2 of the final stage air desorption unit. After surface heat exchange, the heated desulfurization rich liquid and condensate are output to the desulfurization rich liquid header 15; the uncondensed water vapor and SO2 mixture are output to the direct air cooling system 14.

[0053] The method for desorbing sulfur dioxide using a three-stage desulfurization system with rich liquid air conditioning is as follows:

[0054] (1) Send the desulfurized rich liquid into the heat exchanger 13, the desulfurized rich liquid header 15, the regenerated liquid header 17 and all the air desorption chambers 2 of each stage, so that the air desorption chamber 2 reaches the set liquid level value, and the regenerated liquid header 17 reaches the set liquid level value 100mm lower than the liquid level of the first air desorption chamber 2.

[0055] The direct air-cooling system 14 of the final stage desorption unit and the vacuum system 7 of the final stage desorption unit and the second stage desorption unit are started to vent the gas in each stage desorption chamber 2, steam heating chamber 3, heat exchanger 13, direct air-cooling system 14, desulfurization rich liquid header 15, regeneration liquid header 17 and connecting pipelines to the pressure set value required by each desulfurization rich liquid desorption unit.

[0056] Close the bypass valve 12, open the vacuum system 7 of the steam heating chamber 3 of the primary ventilator desorption unit to vent the gas in the steam heating chamber 3, and use high-pressure steam to heat the 50°C turbine exhaust steam to 70°C and send it into the steam heating chamber 3 through the steam jet pump 11.

[0057] (2) The desulfurized rich liquid entering the desulfurization desorption chamber 2 of the first-stage cavitation desorption unit flows from the desorption liquid inlet 8 to the desorption liquid outlet 9 at a set liquid level and flow rate. During this process, it exchanges heat with the steam in the steam heating chamber 3 of this stage through the heating surface 1 and is heated to the set cavitation desorption temperature of 65°C in the desulfurization desorption chamber 2, causing cavitation. This causes SO2 in the desulfurized rich liquid to desorb and alkaline aluminum sulfate to regenerate. The regenerated alkaline aluminum sulfate solution enters the regeneration liquid header 17 through the desorption liquid outlet 9. The SO2 and water vapor mixture generated by desorption at 65°C enters the steam heating chamber 3 of the second-stage cavitation desorption unit through the exhaust port 10. The desulfurized rich liquid in the desulfurization desorption chamber 2 of the first-stage cavitation desorption unit cavits at the set value of 65°C and absorbs heat, which causes the water vapor in the steam heating chamber 3 of this stage to condense into condensate. The condensate is sent back to the heat source regeneration system by the condensate pump 19 through the condensate outlet 5, and the non-condensable gas is discharged by the vacuum system 7 through the gas outlet 6.

[0058] (3) The desulfurized rich liquid entering the desulfurization desorption chamber 2 of the second-stage cavitation desorption unit flows from the desorption liquid inlet 8 to the desorption liquid outlet 9 under the set liquid level and flow rate. During this process, it exchanges heat with the 65°C steam entering the steam heating chamber 3 of this stage through the heating surface 1 and is heated to the 60°C cavitation desorption temperature set in the desulfurization desorption chamber 2 of this stage, which causes cavitation. This causes SO2 in the desulfurized rich liquid to be desorbed and alkaline aluminum sulfate to be regenerated. The regenerated alkaline aluminum sulfate solution enters the regeneration liquid header 17 through the desorption liquid outlet 9. The 60°C SO2 and water vapor mixed gas generated by desorption enters the steam heating chamber 3 of the final-stage cavitation desorption unit through the exhaust port 10. In the desulfurization-rich liquid in the desorption chamber 2 of the second-stage cavitation unit, cavitation occurs at a set temperature of 60°C, absorbing heat and causing water vapor in the steam heating chamber 3 of the second-stage cavitation desorption unit to condense into condensate, which is then separated from SO2 gas. The condensate flows by gravity through the condensate outlet 5 to the desorption chamber 2 of the first-stage cavitation desorption unit, while the SO2 gas is sent to the SO2 utilization process through the gas outlet 6 by the vacuum system 7.

[0059] (4) The desulfurized rich liquid entering the desorption chamber 2 of the final stage cavitation desorption unit, flows from the desorption liquid inlet 8 to the desorption liquid outlet 9 at a set liquid level and flow rate. During this process, it exchanges heat with the 60°C steam entering the steam heating chamber 3 at the heating surface 1, raising its temperature to the set cavitation desorption temperature of 55°C for the desorption chamber 2, causing cavitation. This results in the desorption of SO2 in the desulfurized rich liquid and the regeneration of alkaline aluminum sulfate. The regenerated alkaline aluminum sulfate solution enters the regeneration liquid header 17 through the desorption liquid outlet 9. The 55°C generated during desorption... The water vapor and SO2 mixture at ℃ first enter the heat exchanger 13 under the action of the direct air cooling system 14, and undergo surface heat exchange with the desulfurized rich liquid from the desulfurization system 20 in the heat exchange tube bundle of the heat exchanger 13, causing some water vapor to condense. The uncondensed water vapor and SO2 mixture enter the direct air cooling system 14. The condensate in the heat exchanger 13 flows into the desulfurized rich liquid header 15 by gravity. The desulfurized rich liquid from the desulfurization system 20 enters the desulfurized rich liquid header 15 after being heated by the heat exchanger 13.

[0060] (5) The mixture of water vapor and SO2 entering the direct air cooling system 14 undergoes surface heat exchange with the ambient air. The water vapor condenses and separates from the SO2 gas. The condensate flows through the condensate tank and is collected and flows into the desulfurization rich liquid header 15 by gravity. The SO2 gas is sent to the SO2 utilization process by the vacuum system set in the direct air cooling system 14.

[0061] (6) The regenerated alkaline aluminum sulfate solution entering the regenerated liquid manifold 17 is transported by the regenerated liquid pump 18 to the desulfurization system 20 or partially to the sulfate neutralization system.

[0062] Using existing publicly available technologies or methods, it is possible to adjust and control the relevant parameters of the system for desulfurizing sulfur dioxide in the above-mentioned three-stage desulfurization rich liquid. Following step (1), the desulfurization rich liquid is continuously fed into the heat exchanger 13. Step (1) continuously maintains the saturated steam pressure value corresponding to the set temperature in each stage of the desulfurization desorption chamber 2. Step (1) continuously sends 70°C water vapor into the steam heating chamber 3 of the first-stage desulfurization desorption unit. Step (2) the non-condensable gas in the steam heating chamber 3 of the first-stage desulfurization desorption unit is continuously discharged by the vacuum system 7. Condensate pump 19 delivers condensate from the steam heating chamber 3 of the primary air desorption unit to the heat source regeneration system. Steps (3) and (4) continuously deliver SO2 gas through gas outlet 6 to the SO2 utilization process via vacuum system 7. Step (5) continuously delivers SO2 gas to the SO2 utilization process via vacuum system set in direct air cooling system 14. Step (6) continuously delivers the regenerated alkaline aluminum sulfate solution entering regenerated liquid header 17 to desulfurization system 20 or partially to sulfate neutralization system via regenerated liquid pump 18. By following the above steps, the three-stage desulfurization system rich in liquid air desorption of sulfur dioxide achieves continuous and stable operation.

[0063] Example 2

[0064] Taking a three-stage desulfurization system for desorbing sulfur dioxide using rich liquid cavitation as an example, the cavitation desorption temperature of the alkaline aluminum sulfate desulfurization rich liquid in the desorption chamber 2 of the final stage desulfurization unit is set to 55℃. The inter-stage temperature difference between the desulfurization rich liquid cavitation desorption temperatures of adjacent stages is set to 5℃. The temperature difference between the desulfurization rich liquid cavitation temperature and the steam or steam / SO2 mixture in the steam heating chamber 3 of the same stage desulfurization unit is set to 5℃. The exhaust steam from the turbine operating at a back pressure of 31.16 kPa is used as the heat source for supplying heat for SO2 desorption. The turbine exhaust steam temperature is approximately 70℃, so there is no need to use the steam jet pump 11 for heating. The depth of the desorbed liquid in each stage desorption chamber 2 is set to 300 mm, and the velocity of the desorbed liquid flowing from the desorbed liquid inlet 8 to the desorbed liquid outlet 9 is set to 0.05 m / s.

[0065] like Figure 1 As shown, the structure of the three-stage desulfurization system for desorbing sulfur dioxide by liquid air is exactly the same as that in Example 1, except that the turbine exhaust does not need to be heated by the steam jet pump 11, but can be heated by opening the bypass valve 12.

[0066] The method for desorbing sulfur dioxide in a three-stage desulfurization liquid-rich air-conditioning unit is exactly the same as in Example 1, except that the turbine exhaust steam at 70°C is directly sent into the steam heating chamber 3 of the first-stage air-conditioning desorption unit through the bypass valve 12, without the need for the steam jet pump 11 to raise the temperature.

[0067] This article uses specific examples to illustrate the inventive concept in detail. The description of the above embodiments is only for the purpose of helping to understand the core idea of ​​the present invention. It should be noted that any obvious modifications, equivalent substitutions or other improvements made by those skilled in the art without departing from the inventive concept should be included within the protection scope of the present invention.

Claims

1. A multi-stage desulfurization system for desorbing sulfur dioxide using a liquid-rich air-conditioning system, characterized in that, It includes a multi-stage air desorption unit, each stage of which is divided into upper and lower chambers by a heated surface. The upper chamber is the air desorption chamber and the lower chamber is the steam heating chamber. The lower part of the air desorption chamber is provided with a desorption liquid outlet, and an overflow weir is provided at the desorption liquid outlet to control the liquid level in the air desorption chamber. The exhaust port of the desorption chamber of each pre-stage desorption unit is connected to the steam inlet of the steam heating chamber of the subsequent stage desorption unit via a pipeline; the condensate outlet of the steam heating chamber of each subsequent stage desorption unit is connected to the desorbent inlet of the desorption chamber of the pre-stage desorption unit via a pipeline; the gas outlet of the steam heating chamber from the second stage desorption unit to the final stage desorption unit is connected to the SO2 utilization process via a vacuum system; a vacuum system is installed at the gas outlet of the steam heating chamber of the first stage desorption unit; the condensate outlet of the steam heating chamber of the first stage desorption unit is connected to the heat source recovery system via a condensate pump; the condensate outlets of the steam heating chambers from the second stage desorption unit to the final stage desorption unit are all higher than the desorbent inlet of the pre-stage desorption chamber. The steam inlet of the steam heating chamber of the first-stage cavitation desorption unit is connected to a parallel steam jet pump and a bypass valve. Steam enters the steam heating chamber through the steam jet pump or the bypass valve. The cavitation temperature of the desulfurized rich liquid in the preceding cavitation desorption unit is higher than that of the following cavitation desorption unit. The steam temperature of the steam heating chamber of the same-stage cavitation desorption unit is higher than that of the desulfurized rich liquid in the cavitation desorption chamber. The desulfurization rich liquid header supplies desulfurization rich liquid to the desorption chamber of each stage of the desorption unit. The regenerated solution after desorbing SO2 from the desorption chamber of each stage of the desorption unit is output to the regenerated liquid header. The liquid level in the regenerated liquid header is lower than the overflow weir crest height of the first-stage desorption liquid outlet. The regenerated liquid header and the first-stage desorption chamber are connected to maintain the same internal pressure, forming a free overflow from the overflow weir. The liquid flowing out of the overflow weirs of other stages is introduced into the regenerated liquid header below the liquid surface through downcomers, forming a submerged outflow. This blocks the airflow channels between the desorption chambers of each stage of the desorption unit, providing conditions for differential control of the temperature and pressure setpoints of the desorption chambers of each stage of the desorption unit.

2. The system according to claim 1, characterized in that, The exhaust port of the desorption chamber of the final stage air desorption unit is connected to a heat exchanger and a direct air-cooling system. The gas-side inlet of the heat exchanger is connected to the exhaust port of the desorption chamber of the final stage air desorption unit, and the gas-side outlet of the heat exchanger is connected to the direct air-cooling system.

3. The system according to claim 2, characterized in that, The water-side inlet of the heat exchanger is connected to the desulfurization system, the water-side outlet of the heat exchanger is connected to the desulfurization rich liquid header, the condensate outlet of the heat exchanger and the direct air-cooling system is connected to the desulfurization rich liquid header, and the vacuum system of the direct air-cooling system is connected to the SO2 utilization process flow.

4. A method for multi-stage desulfurization and sulfur dioxide desorption / resorption using a multi-stage desulfurization system with rich liquid air as described in any one of claims 1-3, characterized in that, It includes a multi-stage cavitation desorption unit, which uses the steam generated during cavitation in the desorption chamber of the previous stage as the heating steam for the steam heating chamber of the next stage cavitation desorption unit to desorb SO2 in that stage, so that the heat energy of the desorption steam in the previous stage becomes the heat source for desorption in the next stage.

5. The method according to claim 4, characterized in that, Using industrial exhaust steam as a heat source, with the industrial exhaust steam temperature not exceeding the desulfurization-rich liquid cavitation temperature of the primary cavitation desorption unit, includes the following steps: (1) When the bypass valve is closed, the industrial exhaust steam exchanges energy with the working steam and is heated when it passes through the steam jet pump. The temperature of the heated industrial exhaust steam is higher than the desorption temperature of sulfur dioxide desorbed by the primary air desorption unit. (2) The heated industrial exhaust steam enters the steam heating chamber through the steam inlet of the first-stage cavitation desorption unit. The desulfurized rich liquid in the first-stage cavitation desorption unit undergoes cavitation desorption, and the regeneration solution enters the regeneration liquid header. The SO2 and water vapor mixture generated by desorption enters the steam heating chamber of the next stage cavitation desorption unit through the exhaust port of the first-stage cavitation desorption unit. The non-condensable gas in the steam heating chamber of the first-stage cavitation desorption unit is discharged through the gas outlet via the vacuum system. The condensate in the steam heating chamber of the first-stage cavitation desorption unit is transported to the heat source regeneration system through the condensate outlet by the condensate pump. (3) The desulfurized rich liquid in the desorption chamber of the next stage desorption unit undergoes desorption and cavitation. The regenerated solution enters the regenerated liquid header. The SO2 and water vapor mixture generated by desorption enters the steam heating chamber of the next two stages of desorption units through the exhaust port of the desorption chamber of this stage. The water condensed in the steam heating chamber of the next stage desorption unit flows to the desorption chamber of the first stage desorption unit through the condensate outlet. The SO2 gas in the steam heating chamber of the next stage desorption unit is sent to the SO2 utilization process through the vacuum system via the gas outlet. Step (3) is repeated until the desulfurized rich liquid in the desorption chamber of the final stage desorption unit undergoes desorption. (4) In the desulfurization rich liquid of the desulfurization desorption chamber of the final stage desulfurization desorption unit, desulfurization occurs. The regenerated solution enters the regenerated liquid header. The water vapor and SO2 mixed gas generated by desorption first enter the gas side of the heat exchanger and exchange heat with the desulfurization rich liquid from the desulfurization system on the water side of the heat exchanger. Some of the steam condenses. The uncondensed steam and SO2 enter the direct air cooling system. The water vapor condenses into condensate and is separated from the SO2 gas. The condensate enters the desulfurization rich liquid header, and the SO2 is sent to the utilization process. The condensate from the heat exchanger enters the desulfurization rich liquid header. The desulfurization rich liquid after the water side of the heat exchanger is heated by heat exchange enters the desulfurization rich liquid header.

6. The method according to claim 4, characterized in that, Using industrial exhaust steam as a heat source, with the exhaust steam temperature higher than the cavitation temperature of the desulfurization-rich liquid in the primary system, the process includes the following steps: (1) Open the bypass valve, and the industrial exhaust steam enters the steam heating chamber through the bypass valve and the steam inlet of the primary air desorption unit; (2) The desulfurized rich liquid in the desulfurization desorption chamber of the first-stage desulfurization unit undergoes desulfurization desorption, and the regeneration solution enters the regeneration liquid header. The SO2 and water vapor mixture generated by desorption enters the steam heating chamber of the next stage desulfurization unit through the exhaust port of the desulfurization chamber of this stage. The non-condensable gas in the steam heating chamber of the first-stage desulfurization unit is discharged through the gas outlet via the vacuum system, and the condensate in the steam heating chamber of the first-stage desulfurization unit is transported to the heat source regeneration system through the condensate outlet by the condensate pump. (3) The desulfurized rich liquid in the desorption chamber of the next stage desorption unit undergoes desorption and cavitation. The regenerated solution enters the regenerated liquid header. The SO2 and water vapor mixture generated by desorption enters the steam heating chamber of the next two stages of desorption units through the exhaust port of the desorption chamber of this stage. The water condensed in the steam heating chamber of the next stage desorption unit flows to the desorption chamber of the first stage desorption unit through the condensate outlet. The SO2 gas in the steam heating chamber of the next stage desorption unit is sent to the SO2 utilization process through the vacuum system via the gas outlet. Step (3) is repeated until the desulfurized rich liquid in the desorption chamber of the final stage desorption unit undergoes desorption. (4) In the desulfurization rich liquid of the desulfurization desorption chamber of the final stage desulfurization desorption unit, desulfurization occurs. The regenerated solution enters the regenerated liquid header. The water vapor and SO2 mixed gas generated by desorption first enter the gas side of the heat exchanger and exchange heat with the desulfurization rich liquid from the desulfurization system on the water side of the heat exchanger. Some of the steam condenses. The uncondensed steam and SO2 enter the direct air cooling system. The water vapor condenses into condensate and is separated from the SO2 gas. The condensate enters the desulfurization rich liquid header, and the SO2 is sent to the utilization process. The condensate from the heat exchanger enters the desulfurization rich liquid header. The desulfurization rich liquid after the water side of the heat exchanger is heated by heat exchange enters the desulfurization rich liquid header.

7. The method according to claim 5 or 6, characterized in that, It also includes the following steps: (0) The desulfurization rich liquid is sent into the desorption chamber of each stage of the desorption unit and the regenerated liquid manifold to reach the set liquid level value; The air desorption chambers and steam heating chambers of each air desorption unit, as well as the heat exchangers, direct air cooling system, desulfurization rich liquid header, regeneration liquid header and connecting pipelines, are vented to their respective required pressure settings.

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