Coupling device for desulfurized flue gas of thermal power plant and low-temperature multi-effect seawater desalination and desulfurization method

Abstract

The present invention belongs to the technical field of flue gas desulfurization, and provides a coupling device for desulfurization flue gas of a thermal power plant and low-temperature multi-effect seawater desalination, as well as a desulfurization method. The two ends of the raw seawater feed pipeline are respectively connected to the outlet of the low-temperature multi-effect seawater desalination device and the flue gas desulfurization device, and the two ends of the main feed pipe are respectively connected to the inlet of the low-temperature multi-effect seawater desalination device and the flue gas desulfurization device. It solves the problems that in places where there are both coal-fired boilers and thermal low-temperature multi-effect seawater desalination devices, scaling is likely to occur in the low-temperature multi-effect seawater desalination device, the descaling and desulfurization work are carried out separately and cannot be effectively combined, and the desulfurization raw materials of the desulfurization device are consumed in large quantities, with high costs, and the acidic waste generated cannot be effectively utilized, resulting in a large amount of resource waste. It has the effects of saving resources and costs.

Description

Technical Field

[0001] The present invention relates to the technical field of flue gas desulfurization, and particularly to a coupling device and a desulfurization method for desulfurized flue gas of a thermal power plant and low-temperature multi-effect seawater desalination. Background Art

[0002] Flue gas from thermal power plants and boilers contains sulfur dioxide and dust. Both sulfur dioxide and dust are the main components of air pollutants. Sulfur dioxide is the main cause of acid rain, and dust with smaller particle sizes is one of the main culprits of smog. According to the "2015 Environmental Bulletin" released by the Ministry of Environmental Protection of China, the precipitation monitoring results of 480 cities (districts, counties) in China show that: the average acid rain frequency is 14.0%, the proportion of cities with acid rain is 40.4%, the proportion of cities with an acid rain frequency above 25% is 20.8%, the proportion of cities with an acid rain frequency above 50% is 12.7%, and the proportion of cities with an acid rain frequency above 75% is 5.0%; the anion in precipitation is sulfate, accounting for 24.7% of the total ion amount, and the overall type of acid rain is still sulfuric acid type.

[0003] With the increasingly serious environmental pollution and frequent smog events, the country has paid more and more attention to environmental protection. In recent years, a series of environmental protection laws, regulations, national standards and management measures have been introduced. GB13271-2014 "Emission Standards for Air Pollutants from Boilers" stipulates that the SO2 concentration limits for flue gas emissions from newly built coal-fired boilers, oil-fired boilers and gas-fired boilers are 300, 200, 50 mg / Nm3 respectively, and the SO2 concentration limits for flue gas emissions from coal-fired boilers, oil-fired boilers and gas-fired boilers in key areas are 200, 100, 50 mg / Nm3 respectively. GB 13223-2011 "Emission Standards for Air Pollutants from Thermal Power Plants" stipulates that SO2 in flue gas from newly built coal-fired boilers ≯ 100 mg / Nm3, and SO2 in coal-fired boilers in key areas ≯ 50 mg / Nm3. The "Work Plan for the Full Implementation of Ultra-low Emission and Energy Conservation Reconstruction of Coal-fired Power Plants" (No. 164

[2015] of the Ministry of Environmental Protection) stipulates that the ultra-low emission index for flue gas of coal-fired power plants is: SO2 ≯ 35 mg / Nm3. GB31570-2015 "Emission Standards for Pollutants from Petroleum Refining Industry" stipulates that for flue gas from the regeneration of catalytic cracking catalysts, SO2 ≯ 100 mg / Nm3, and in key areas, SO2 ≯ 50 mg / Nm3.

[0004] Wet desulfurization has the advantages of high desulfurization efficiency, reliable operation of the device, simple operation, etc. Therefore, the existing flue gas desulfurization technologies in the world mainly focus on wet desulfurization. Traditional wet desulfurization technologies mainly include limestone-gypsum method, double-alkali desulfurization, sodium-alkali desulfurization, ammonia desulfurization method, etc. The above flue gas desulfurization technologies mainly adopt countercurrent spraying, and the alkaline slurry is sprayed from the top of the desulfurization tower, and free settlement occurs under the action of gravity to contact the flue gas countercurrently to achieve the desulfurization reaction.

[0005] On January 30, 2018, the State Intellectual Property Office published an invention patent with the application number CN201810092897.3 and the title "Flue Gas Desulfurization System and Method for Flue Gas Desulfurization Using the Flue Gas Desulfurization System". The following is part of the content in the invention patent specification: "The absorption part is realized through a quenching section and an absorption section. The quenching section is used for the rapid cooling and efficient absorption of the tail gas, and the absorption section is used for the fine absorption of the tail gas and the capture of dust and mist. The cooled temperature-reduced tail gas 22 in the heat pipe type flue gas heat exchanger 7 enters the spray area of the quenching section 8 from the top of the quenching section 8. The quenching circulation pump 12 transports the quenching circulation liquid to the spray layer at the upper part of the quenching section. The spray layer sprays the quenching circulation liquid along the direction of the flue gas flow. The quenching circulation liquid contacts the flue gas in a co-current manner. The flue gas undergoes mass transfer and chemical reactions with the quenching circulation liquid containing sodium sulfite, sodium bisulfite, sodium sulfate, and added sodium alkali, so that 90-95% of the sulfur dioxide in the flue gas is absorbed and converted into sodium sulfite, and the high-temperature flue gas is cooled. After the flue gas is cooled from 150-220°C to about 55-75°C, it enters the absorption section. When the storage tank is not full, the quenching circulation liquid after contacting the flue gas enters the storage tank, and then returns to the spray layer through the pipeline and circulation pump in the quenching loop; when the storage tank is full of the quenching circulation liquid, part of the quenching circulation liquid enters the packed absorption tower together with the flue gas through the connecting pipe."

[0006] In the prior art, in places where there are both coal-fired boilers and thermal low-temperature multi-effect seawater desalination devices, scaling easily occurs in the low-temperature multi-effect seawater desalination device. The descaling and desulfurization operations are carried out separately and cannot be effectively combined. Moreover, the desulfurization raw materials of the desulfurization device consume a large amount, the cost is high, and the acidic waste generated cannot be effectively utilized, resulting in a large amount of resource waste. Summary of the Invention

[0007] In order to solve the above technical problems that in places where there are both coal-fired boilers and thermal low-temperature multi-effect seawater desalination devices, scaling easily occurs in the low-temperature multi-effect seawater desalination device, the descaling and desulfurization operations are carried out separately and cannot be effectively combined. Moreover, the desulfurization raw materials of the desulfurization device consume a large amount, the cost is high, and the acidic waste generated cannot be effectively utilized, resulting in a large amount of resource waste, the present invention provides a coupling device and desulfurization method for desulfurized flue gas of a thermal power plant and low-temperature multi-effect seawater desalination.

[0008] The coupling device for desulfurized flue gas of a thermal power plant and low-temperature multi-effect seawater desalination includes: a raw seawater feed pipeline, a main discharge pipeline, and a flue gas desulfurization device. The two ends of the raw seawater feed pipeline are respectively communicated with the discharge port of the low-temperature multi-effect seawater desalination device and the flue gas desulfurization device, and the two ends of the main discharge pipeline are respectively communicated with the feed port of the low-temperature multi-effect seawater desalination device and the flue gas desulfurization device.

[0009] Further, the raw seawater feed pipeline includes: a feed pump, a main raw seawater feed pipe, a first-stage raw seawater branch pipe, and a second-stage raw seawater branch pipe. One end of the main raw seawater feed pipe is connected to the discharge port of the low-temperature multi-effect seawater desalination device, and the other end of the main raw seawater feed pipe is provided with the first-stage raw seawater branch pipe and the second-stage raw seawater branch pipe. Both the first-stage raw seawater branch pipe and the second-stage raw seawater branch pipe are connected to the flue gas desulfurization device.

[0010] Further, the flue gas desulfurization device includes: a flue gas inlet tower, a flue, and a flue gas outlet tower. The flue is divided into a horizontal flue and a vertical flue. The horizontal flue and the vertical flue are connected through a bend. The flue gas inlet tower is connected to the horizontal flue, and the vertical flue is arranged inside the flue gas outlet tower.

[0011] Further, the flue gas inlet tower is provided with an original flue gas inlet, and a dust filter screen is arranged at the connection between the flue gas inlet tower and the horizontal flue.

[0012] Further, a front water baffle and a rear water baffle are arranged on the lower wall of the horizontal flue. A collection port is arranged between the front water baffle and the rear water baffle, and the main discharge pipe is connected to the collection port.

[0013] Further, a discharge pump is arranged on the main discharge pipe.

[0014] Further, a discharged water PH detector and a sodium hydroxide addition pipe are arranged on the main discharge pipe.

[0015] Further, a first-stage regulating valve and a first-stage raw seawater nozzle are arranged on the first-stage raw seawater branch pipe, and a second-stage regulating valve and a second-stage raw seawater nozzle are arranged on the second-stage raw seawater branch pipe. The first-stage regulating valve and the second-stage regulating valve are located outside the horizontal flue, and the first-stage raw seawater nozzle and the second-stage raw seawater nozzle are located above the inside of the horizontal flue.

[0016] Further, the first-stage raw seawater nozzle and the second-stage raw seawater nozzle are arranged in a staggered manner up and down.

[0017] The desulfurization method of the desulfurization flue gas and low-temperature multi-effect seawater desalination coupling device in a thermal power plant is as follows:

[0018] S1: Use the feed pump to transport the seawater in the low-temperature multi-effect seawater desalination device through the main raw seawater feed pipe to the first-stage raw seawater branch pipe and the second-stage raw seawater branch pipe, and then make the seawater spray out from the first-stage raw seawater nozzle and the second-stage raw seawater nozzle.

[0019] S2: Feed the raw flue gas into the inlet flue tower from the raw flue gas inlet. The raw flue gas is first filtered by the dust filter screen to remove dust, and then when passing through the horizontal flue, sulfur dioxide in the raw flue gas reacts with the seawater sprayed from the first-stage raw seawater nozzle and the second-stage raw seawater nozzle. The sulfur dioxide is absorbed, and the desulfurized clean flue gas is discharged from the upper outlet of the vertical flue.

[0020] S3: The seawater that has reacted with sulfur dioxide in the raw flue gas is blocked by the front baffle and the rear baffle and concentrated at the collection port. Use the discharge pump to transport the reacted seawater through the main discharge pipe to the low-temperature multi-effect seawater desalination device. Detect the pH value of the reacted seawater through the discharge water pH detector, and adjust the pH value of the reacted seawater by adding sodium hydroxide in the sodium hydroxide addition pipe.

[0021] The beneficial effects of the present invention are:

[0022] The present invention provides a coupling device and a desulfurization method for desulfurizing flue gas in a thermal power plant and low-temperature multi-effect seawater desalination. By connecting the feed inlet of the desulfurization device to the discharge outlet of the low-temperature multi-effect seawater desalination device, and connecting the discharge outlet of the desulfurization device to the feed inlet of the low-temperature multi-effect seawater desalination device, the alkaline seawater in the low-temperature multi-effect seawater desalination device is fully utilized as a desulfurization raw material. Use the feed pump to spray the seawater from the nozzle to react with sulfur dioxide in the flue gas. The reacted seawater is returned to the low-temperature multi-effect seawater desalination device under the action of the pump through the discharge pipe. Since the reacted seawater absorbs sulfur dioxide and becomes acidic, it effectively avoids scaling in the low-temperature multi-effect seawater desalination device. The raw seawater feed pipeline, the main discharge pipe, the flue gas desulfurization device, and the low-temperature multi-effect seawater desalination device form a closed loop. The materials in it are recycled, making resources fully utilized and greatly saving resources. The present invention solves the problems of scaling and oxygen corrosion in the low-temperature multi-effect seawater desalination device while realizing flue gas desulfurization. The desulfurization raw material is recycled, with the effects of saving resources and cost, and is widely used in places where there are both coal-fired boilers and thermal low-temperature multi-effect seawater desalination devices. Description of the Drawings

[0023] In order to more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the following will briefly introduce the drawings required for use in the description of the specific embodiments or the prior art. Obviously, the drawings in the following description are some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0024] Figure 1 It is a schematic structural diagram of the present invention;

[0025] Wherein:

[0026] Raw seawater feed pipeline - 1, main discharge pipe - 2, flue gas desulfurization device - 3, feed pump - 11, main raw seawater feed pipe - 12, first - stage raw seawater branch pipe - 13, second - stage raw seawater branch pipe - 14, flue gas inlet tower - 31, flue - 32, exhaust tower - 33, horizontal flue - 301, vertical flue - 302, raw flue gas inlet - 311, dust filter net - 312, front water baffle - 321, rear water baffle - 322, collection port - 323, discharge pump - 21, discharge water pH detector - 22, sodium hydroxide addition pipe - 23, first - stage regulating valve - 131, first - stage raw seawater nozzle - 132, second - stage regulating valve - 141, second - stage raw seawater nozzle - 142. Detailed implementation mode

[0027] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without making creative efforts belong to the protection scope of the present invention.

[0028] It should be noted that the installation methods and technical terms mentioned in the present invention are all well - known technical terms in the technical field, so no more explanations will be made. In addition, the same reference numerals are used for the same components, but this does not affect and should not constitute an inaccurate understanding of the technical solution by those skilled in the art.

[0029] Embodiment 1:

[0030] The present invention relates to a coupling device for desulfurization of flue gas in a thermal power plant and low - temperature multi - effect seawater desalination, including: a raw seawater feed pipeline 1, a main discharge pipe 2, and a flue gas desulfurization device 3. The two ends of the raw seawater feed pipeline 1 are respectively connected to the discharge port of the low - temperature multi - effect seawater desalination device and the flue gas desulfurization device 3, and the two ends of the main discharge pipe 2 are respectively connected to the feed port of the low - temperature multi - effect seawater desalination device and the flue gas desulfurization device 3. The seawater flow direction is as Figure 1As shown by the solid arrow in the figure, since the low-temperature multi-effect seawater desalination device is a well-known prior art to those skilled in the art, its specific structure will not be described in detail. By connecting the two ends of the raw seawater feed pipeline 1 to the outlet of the low-temperature multi-effect seawater desalination device and the flue gas desulfurization device 3 respectively, and connecting the two ends of the main discharge pipeline 2 to the inlet of the low-temperature multi-effect seawater desalination device and the flue gas desulfurization device 3 respectively, the alkaline seawater in the low-temperature multi-effect seawater desalination device is used as the desulfurization raw material to react with sulfur dioxide in the flue gas, greatly reducing the cost of the desulfurization raw material. The seawater after reacting with sulfur dioxide contains sulfurous acid or bisulfite and thus is acidic. Returning it to the low-temperature multi-effect seawater desalination device avoids scale formation, solves the problems of scale formation and oxygen corrosion in the low-temperature multi-effect seawater desalination device while realizing flue gas desulfurization. The raw seawater feed pipeline 1, the main discharge pipeline 2, the flue gas desulfurization device 3 and the low-temperature multi-effect seawater desalination device form a closed loop, and the desulfurization raw material is recycled, greatly saving resources.

[0031] The raw seawater feed pipeline 1 includes: a feed pump 11, a raw seawater feed main pipe 12, a first-section raw seawater branch pipe 13 and a second-section raw seawater branch pipe 14. One end of the raw seawater feed main pipe 12 is connected to the outlet of the low-temperature multi-effect seawater desalination device, and the other end of the raw seawater feed main pipe 12 is provided with the first-section raw seawater branch pipe 13 and the second-section raw seawater branch pipe 14. Both the first-section raw seawater branch pipe 13 and the second-section raw seawater branch pipe 14 are connected to the flue gas desulfurization device 3. By setting the branch pipes to disperse the alkaline seawater, and installing spray nozzles on the branch pipes, the contact area between the alkaline seawater and sulfur dioxide in the flue gas is increased, improving the desulfurization efficiency.

[0032] The flue gas desulfurization device 3 includes: a flue gas inlet tower 31, a flue 32 and a flue gas outlet tower 33. The flue 32 is divided into a horizontal flue 301 and a vertical flue 302, and the horizontal flue 301 and the vertical flue 302 are connected through a bent pipe. The flue gas inlet tower 31 is connected to the horizontal flue 301, and the vertical flue 302 is arranged inside the flue gas outlet tower 33. The flue gas flow direction is as Figure 1 shown by the hollow arrow in the figure. Setting the horizontal flue 301 improves the reaction efficiency between the alkaline seawater and sulfur dioxide in the flue gas, and the desulfurized flue gas is smoothly discharged into the atmosphere through the vertical flue 302.

[0033] The flue gas inlet tower 31 is provided with a raw flue gas inlet 311, and a dust filter screen 312 is arranged at the connection between the flue gas inlet tower 31 and the horizontal flue 301. The large-particle dust in the flue gas is filtered through the dust filter screen 312 to avoid affecting the desulfurization effect.

[0034] A front water baffle 321 and a rear water baffle 322 are arranged on the lower wall of the horizontal flue 301. A collection port 323 is arranged between the front water baffle 321 and the rear water baffle 322. The discharge main pipe 2 is communicated with the collection port 323. By arranging the front water baffle 321 and the rear water baffle 322, the seawater reacted with the flue gas is collected.

[0035] A discharge pump 21 is arranged on the discharge main pipe 2.

[0036] A discharge water PH detector 22 and a sodium hydroxide addition pipe 23 are arranged on the discharge main pipe 2. To prevent acid corrosion of the seawater desalination equipment, a small amount of sodium hydroxide solution needs to be added to adjust the PH to 7-8, and sodium sulfite is generated at the same time. During the seawater desalination process, sodium sulfite reacts with residual oxygen to generate sodium sulfate, and the residual oxygen is consumed, thereby avoiding or slowing down the oxygen corrosion under the bare metal surface or under the sediment. During normal operation, sodium hydroxide is configured and stored in the chemical dosing metering tank. Sodium hydroxide enters the interior of the seawater desalination device along with the incoming feed seawater. Inside the seawater desalination device, the incoming feed seawater is heated during the process of producing desalinated water, and the chemical agent reacts chemically with the dissolved oxygen, bactericide, etc. in the seawater, and then the dissolved oxygen is consumed completely, thereby avoiding the reaction between the dissolved oxygen and the bare metal. At the same time, since the scaling substance carbonate in the incoming feed water is removed, the scaling tendency of the heat exchange surface is slowed down.

[0037] A first-stage regulating valve 131 and a first-stage raw seawater nozzle 132 are arranged on the first-stage raw seawater branch pipe 13, and a second-stage regulating valve 141 and a second-stage raw seawater nozzle 142 are arranged on the second-stage raw seawater branch pipe 14. The first-stage regulating valve 131 and the second-stage regulating valve 141 are located outside the horizontal flue 301, and the first-stage raw seawater nozzle 132 and the second-stage raw seawater nozzle 142 are located above the interior of the horizontal flue 301. By arranging the nozzles, the contact area between the alkaline seawater and sulfur dioxide in the flue gas is increased, and the reaction efficiency is effectively improved.

[0038] The first-stage raw seawater nozzle 132 and the second-stage raw seawater nozzle 142 are arranged in a staggered manner up and down. Such an arrangement makes the alkaline seawater sprayed by the nozzles cover the space comprehensively and improves the desulfurization effect.

[0039] The present invention relates to a desulfurization method for a coupling device of desulfurization flue gas and low-temperature multi-effect seawater desalination in a thermal power plant. The specific steps are as follows:

[0040] S1: Use the feed pump 11 to transport the seawater in the low-temperature multi-effect seawater desalination device through the raw seawater feed main pipe 12 to the first-stage raw seawater branch pipe 13 and the second-stage raw seawater branch pipe 14, and then make the seawater spray out from the first-stage raw seawater nozzle 132 and the second-stage raw seawater nozzle 142.

[0041] S2: Feed the raw flue gas into the flue gas inlet tower 31 from the raw flue gas inlet 311. The raw flue gas is first filtered by the dust filter screen 312 to remove dust. Then, when passing through the horizontal flue 301, sulfur dioxide in the raw flue gas reacts with the seawater sprayed from the first-stage raw seawater nozzle 132 and the second-stage raw seawater nozzle 142. The sulfur dioxide is absorbed, and the desulfurized clean flue gas is discharged from the upper outlet of the vertical flue 302.

[0042] S3: The seawater that has reacted with sulfur dioxide in the raw flue gas is blocked by the front baffle 321 and the rear baffle 322 and concentrated at the collection port 323. Use the discharge pump 21 to transport the reacted seawater through the discharge main pipe 2 to the low-temperature multi-effect seawater desalination device. Detect the pH value of the reacted seawater through the discharge water pH detector 22, and adjust the pH value of the reacted seawater by adding sodium hydroxide in the sodium hydroxide addition pipe 23.

[0043] Working principle:

[0044] The present invention uses the seawater of the low-temperature multi-effect device to absorb part of the residual sulfur dioxide in the desulfurized clean flue gas. Since seawater is a complex electrolyte solution and contains a certain amount of dissolved oxygen, and in addition, seawater usually contains a certain amount of bicarbonate, which is converted into carbonate due to heating and concentration during the seawater desalination process. The carbonate combines with the hardness calcium and magnesium in the seawater to form insoluble calcium carbonate, magnesium hydroxide, etc. Therefore, seawater has a certain alkalinity. After absorbing sulfur dioxide, the sulfur dioxide content in the flue gas is further reduced and then discharged into the atmosphere. After the alkaline seawater absorbs sulfur dioxide, the effect of flue gas desulfurization is achieved, and the water quality becomes acidic. After sulfur dioxide reacts with the bicarbonate in the water, carbonic acid is produced, and carbon dioxide is released and discharged with the flue gas. And the carbon dioxide in the flue gas cannot be dissolved in the acidic water, thus eliminating the scaling substances carbonate or bicarbonate in the water. The feed water absorbs sulfur dioxide to form sulfurous acid or bisulfite. To prevent acid corrosion of the seawater desalination equipment, a small amount of sodium hydroxide solution needs to be added to adjust the pH to 7-8, and at the same time, sodium sulfite is produced. During the seawater desalination process, sodium sulfite reacts with the residual oxygen to form sodium sulfate, and the residual oxygen is consumed, thus avoiding or slowing down the oxygen corrosion under the bare metal surface or sediment. In the invention, in order to eliminate the alkalinity in the feed water, maintain the sulfur dioxide absorption amount and reduce the sodium hydroxide addition amount, the pH value of the drained water after absorbing sulfur dioxide is controlled to be 3-4.

[0045] For those skilled in the art, the present invention is not limited to the details of the above-described exemplary embodiments, and the present invention can be implemented in other specific forms without departing from the spirit or essential characteristics of the present invention. Therefore, in any aspect, the embodiments should be regarded as exemplary and non-limiting. The scope of the present invention is defined by the appended claims rather than the above description. Therefore, all changes falling within the meaning and scope of the equivalent elements of the claims are intended to be embraced within the present invention. Any reference signs in the claims should not be construed as limiting the claims involved.

[0046] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. Any minor modifications, equivalent replacements, and improvements made to the above embodiments based on the technical essence of the present invention should be included within the protection scope of the technical solution of the present invention.

Claims

1. Flue gas desulfurization and low-temperature multi-effect seawater desalination coupling device for thermal power plants, Characterized in that, Comprising: Raw seawater feed pipeline (1), discharge main pipe (2) and flue gas desulfurization device (3), both ends of the raw seawater feed pipeline (1) are respectively communicated with the discharge port of the low-temperature multi-effect seawater desalination device and the flue gas desulfurization device (3), and both ends of the discharge main pipe (2) are respectively communicated with the feed port of the low-temperature multi-effect seawater desalination device and the flue gas desulfurization device (3); The flue gas desulfurization device (3) comprises: a smoke inlet tower (31), a flue (32) and a smoke exhaust tower (33), the flue (32) is divided into a horizontal flue (301) and a vertical flue (302), the horizontal flue (301) and the vertical flue (302) are communicated through a bend pipe, the smoke inlet tower (31) is communicated with the horizontal flue (301), and the vertical flue (302) is arranged in the smoke exhaust tower (33); a front water baffle (321) and a rear water baffle (322) are arranged on the lower wall of the horizontal flue (301), a collection port (323) is arranged between the front water baffle (321) and the rear water baffle (322), and the discharge main pipe (2) is communicated with the collection port (323).

2. The flue gas desulfurization and low-temperature multi-effect seawater desalination coupling device for thermal power plants according to claim 1, Characterized in that, The raw seawater feed pipeline (1) comprises: a feed pump (11), a raw seawater feed main pipe (12), a first-stage raw seawater branch pipe (13) and a second-stage raw seawater branch pipe (14), one end of the raw seawater feed main pipe (12) is connected to the discharge port of the low-temperature multi-effect seawater desalination device, the other end of the raw seawater feed main pipe (12) is provided with the first-stage raw seawater branch pipe (13) and the second-stage raw seawater branch pipe (14), and both the first-stage raw seawater branch pipe (13) and the second-stage raw seawater branch pipe (14) are connected to the flue gas desulfurization device (3).

3. The flue gas desulfurization and low-temperature multi-effect seawater desalination coupling device for thermal power plants according to claim 1, Characterized in that, The smoke inlet tower (31) is provided with a raw flue gas inlet (311), and a dust filter screen (312) is arranged at the connection between the smoke inlet tower (31) and the horizontal flue (301).

4. The flue gas desulfurization and low-temperature multi-effect seawater desalination coupling device for thermal power plants according to claim 1, Characterized in that, A discharge pump (21) is arranged on the discharge main pipe (2).

5. The flue gas desulfurization and low-temperature multi-effect seawater desalination coupling device for thermal power plants according to claim 4, Characterized in that, A discharge water pH detector (22) and a sodium hydroxide addition pipe (23) are arranged on the discharge main pipe (2).

6. The flue gas desulfurization and low-temperature multi-effect seawater desalination coupling device for thermal power plants according to claim 2, Characterized in that, A first-stage regulating valve (131) and a first-stage raw seawater nozzle (132) are provided on the first-stage raw seawater branch pipe (13), and a second-stage regulating valve (141) and a second-stage raw seawater nozzle (142) are provided on the second-stage raw seawater branch pipe (14). The first-stage regulating valve (131) and the second-stage regulating valve (141) are located outside the horizontal flue (301), and the first-stage raw seawater nozzle (132) and the second-stage raw seawater nozzle (142) are located above the interior of the horizontal flue (301).

7. The coupling device for desulfurization flue gas of a thermal power plant and low-temperature multi-effect seawater desalination according to claim 6, characterized in that the first-stage raw seawater nozzle (132) and the second-stage raw seawater nozzle (142) are arranged staggeredly up and down.

8. A desulfurization method based on the coupling device for desulfurization flue gas of a thermal power plant and low-temperature multi-effect seawater desalination according to any one of claims 1-7, characterized in that the specific steps are as follows: S1: Use a feed pump (11) to transport seawater in the low-temperature multi-effect seawater desalination device through a raw seawater feed main pipe (12) to the first-stage raw seawater branch pipe (13) and the second-stage raw seawater branch pipe (14), and then make the seawater spray out from the first-stage raw seawater nozzle (132) and the second-stage raw seawater nozzle (142); S2: Introduce the raw flue gas from the raw flue gas inlet (311) into the flue gas inlet tower (31). The raw flue gas is first filtered by a dust filter screen (312) to remove dust, and then when passing through the horizontal flue (301), sulfides in the raw flue gas react with the seawater sprayed out from the first-stage raw seawater nozzle (132) and the second-stage raw seawater nozzle (142), and the sulfides are absorbed. The desulfurized clean flue gas is discharged from the upper outlet of the vertical flue (302); S3: The seawater that has reacted with the sulfides in the raw flue gas is blocked by a front water baffle (321) and a rear water baffle (322) and concentrated at the collection port (323). Use a discharge pump (21) to transport the reacted seawater through a discharge main pipe (2) to the low-temperature multi-effect seawater desalination device, detect the pH value of the reacted seawater through a discharged water pH detector (22), and adjust the pH value of the reacted seawater by adding sodium hydroxide in a sodium hydroxide addition pipe (23).

Images