Desulfurizing tower tube bundle demister enhanced washing and overtemperature protection device and method

Abstract

The invention relates to the technical field of flue gas treatment of a desulfurization system of a thermal power plant, in particular to an enhanced flushing and overtemperature protection device and method for a tube bundle demister of a desulfurization tower. An inlet of a demister flushing water pump is connected with a water source, an outlet is connected with an electric valve, and the electric valve is connected with a top flushing pipe; the inlet of the first bypass pipe is connected with the water inlet pipe, and the outlet is connected with the junction of the power-off self-opening valve A and the demister flushing water pump; an inlet of a second bypass pipe is connected with a pipeline between the demister flushing water pump and the electric valve, an outlet is connected with a bottom flushing pipe, and a power-off self-opening valve B is mounted on the second bypass pipe; the invention aims to solve the problem that scaling at the bottom of the tube bundle demister cannot be flushed, and meanwhile, the over-temperature protection effect on the demister is realized in an accident state, and the occurrence of over-temperature damage of the demister can be avoided under the condition of ensuring the operation efficiency of the demister.

Description

Technical Field

[0001] The invention relates to the technical field of flue gas treatment of a desulfurization system in a thermal power plant, and in particular to an enhanced flushing and over-temperature protection device for a desulfurization tower tube bundle demister. Background Art

[0002] The wet flue gas desulfurization system is the most widely used process for sulfur dioxide treatment in flue gas. The wet flue gas after slurry circulation spraying contains a large number of droplets carrying smoke and slurry particles. The droplets are intercepted by the demister to further reduce the carryover of flue gas droplets and reduce the generation of gypsum rain. The tube bundle demister increases the flue gas flow rate and the principle of centrifugal separation for better droplet removal, and is currently widely used. During long-term operation, the demister will experience slurry deposition and even scaling blockage, which will lead to an increase in the demister pressure difference, a decrease in the demisting efficiency, and an excess of flue gas particulate matter indicators. In severe cases, the demister will collapse. Conventional tube bundle demisters are equipped with a matching flushing system, which is sent to the inside of the tube bundle demister assembly through the demister water pump and pipeline to flush the demister cylinder guide vanes to control the internal fouling of the demister.

[0003] Although the flushing system of the tube bundle demister can flush the guide vanes inside the demister assembly, the scale attached to the bottom of the tube bundle demister assembly and the supporting grid cannot be flushed during the long-term operation of the system, which will cause serious scaling blockage. At the same time, during the system circulation pump tripping and standby pump startup process or the desulfurization system power failure and boiler shutdown process, a large amount of high-temperature flue gas will still enter the desulfurization tower, causing high-temperature damage to the demister assembly.

[0004] Therefore, developing a device that can independently realize enhanced flushing of the bottom components and grilles of the tube bundle demister can better control the fouling of the demister. At the same time, when the system circulation pump trips, the standby pump is started, or the desulfurization system loses power, the enhanced flushing device can be put into use to spray and cool the high-temperature flue gas. Summary of the invention

[0005] The present invention mainly aims at the problem that the bottom and grid of the wet flue gas demisting tube bundle demister assembly cannot be flushed, causing scaling and blockage, thereby affecting the demisting performance of the demister and increasing the pressure resistance to cause the induced draft fan to be blocked, as well as the problem that high-temperature flue gas causes high-temperature damage to the demister when the system circulating pump trips or the system loses power.

[0006] According to one aspect of the present invention, a desulfurization tower tube bundle demister enhanced flushing and over-temperature protection device is provided, comprising: Demister flushing water pump, first bypass pipe, second bypass pipe, bottom flushing pipe and top flushing pipe; The inlet of the demister flushing water pump is connected to a water source, the outlet is connected to an electric valve, and the electric valve is connected to a top flushing pipe; The inlet of the first bypass pipe is connected to a water source, and the outlet is connected to a pipeline between a defogger flushing water pump and an electric valve. A power-off self-opening valve A is installed on the first bypass pipe; The inlet of the second bypass pipe is connected to the pipeline between the defogger flushing water pump and the electric valve, and the outlet is connected to the bottom flushing pipe. The second bypass pipe is equipped with a power-off self-opening valve B; The top flushing pipe and the bottom flushing pipe are installed on the demister, the top flushing pipe is used to flush the guide vanes, and the bottom flushing pipe is used to flush the bottom of the demister.

[0007] Preferably, the inlet of the process water tank is connected to a water inlet pipe, and the outlet is connected to a demister flushing water pump.

[0008] Preferably, the inlet of the automatic backwash filter is connected to an electric valve, and the outlet is connected to a top flushing pipe.

[0009] Preferably, the inlet of the Y-type filter is connected to a valve B that opens automatically when power is cut off, and the outlet is connected to a bottom flushing pipe.

[0010] Preferably, the inlet of the enhanced flushing nozzle is connected to the flushing pipe at the bottom of the demister, and the outlet performs enhanced flushing on the bottom of the demister; According to one aspect of the present invention, a method for enhanced flushing and over-temperature protection flushing of a desulfurization tower tube bundle demister is provided, comprising: Start the demister flushing water pump, open the electric valve, and flush the top of the tube bundle demister through the top flushing pipe; After the preset time, the electric valve is closed, the power-off self-opening valve B is opened, and the flushing water passes through the first bypass pipe and then through the bottom flushing pipe to flush the bottom of the tube bundle demister; When the electric valve is powered off, the power-off self-opening valve B opens, and the flushing water enters the second bypass pipe to flush the bottom of the tube bundle demister; When the demister flushing water pump and electric valve are powered off, the power-off self-opening valve A and the power-off self-opening valve B open, and the flushing water enters the first bypass pipe and the second bypass pipe to flush the bottom of the tube bundle demister.

[0011] Preferably, the pressure during flushing is 0.4-0.5Mpa; The predetermined flushing interval is: 3600~7200s.

[0012] Preferably, the bottom flushing time is 2 to 4 minutes.

[0013] The present invention has at least the following beneficial effects: The present invention discloses a device and method for enhanced flushing and over-temperature protection of a desulfurization tower tube bundle demister, which can solve the problem of fouling and blockage of the bottom and grille of a wet desulfurization tube bundle demister due to the inability to be flushed. For a desulfurization system that runs for a long period of time, it can avoid the problem of increased piezoresistance of the demister caused by fouling, which in turn affects the demisting effect. During the process of starting the standby pump when the desulfurization system circulating pump trips and when the system loses power, the device of the present invention can be quickly put into use to spray and cool down the hot flue gas, avoiding over-temperature damage to the demister and ensuring safe and stable operation of the demister. It is of great significance in ensuring the demisting performance of the tube bundle demister and avoiding over-temperature damage to the equipment. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 The present invention is a schematic structural diagram of a desulfurization tower tube bundle demister enhanced flushing and over-temperature protection device according to an embodiment of the present invention.

[0015] In the figure: 1-water inlet pipe, 2-process water tank, 3-demister flushing water pump, 4-electric valve, 5-automatic backwashing filter, 6-top flushing pipe, 7-first bypass pipe, 8-power-off automatic opening valve A, 9-power-off automatic opening valve B, 10-second bypass pipe, 11-Y-type filter. 12-bottom flushing pipe, 13-enhanced flushing nozzle, 14-tube bundle demister. DETAILED DESCRIPTION

[0016] Various exemplary embodiments, features and aspects of the present invention will be described in detail below with reference to the accompanying drawings. The same reference numerals in the accompanying drawings represent elements with the same or similar functions. Although various aspects of the embodiments are shown in the accompanying drawings, the drawings are not necessarily drawn to scale unless otherwise specified.

[0017] The word “exemplary” is used exclusively herein to mean “serving as an example, example, or illustration.” Any embodiment described herein as “exemplary” is not necessarily to be construed as preferred or advantageous over other embodiments.

[0018] The term "and / or" herein is only a description of the association relationship of the associated objects, indicating that there may be three relationships. For example, A and / or B can represent: A exists alone, A and B exist at the same time, and B exists alone. In addition, the term "at least one" herein represents any combination of at least two of any one or more of a plurality of. For example, including at least one of A, B, and C can represent including any one or more elements selected from the set consisting of A, B, and C.

[0019] In addition, in order to better illustrate the present invention, numerous specific details are provided in the following specific embodiments. It should be understood by those skilled in the art that the present invention can be implemented without certain specific details. In some examples, methods, means, components and circuits well known to those skilled in the art are not described in detail in order to highlight the subject matter of the present invention.

[0020] Figure 1 This is a schematic diagram of the structure of a desulfurization tower tube bundle demister enhanced flushing and over-temperature protection device according to an embodiment of the present invention. Figure 1 As shown, a desulfurization tower tube bundle demister enhanced flushing and over-temperature protection device includes: a demister flushing water pump 3, a first bypass pipe 7, a second bypass pipe 10, a bottom flushing pipe 12 and a top flushing pipe 6; The inlet of the demister flushing water pump 3 is connected to a water source, and the outlet is connected to an electric valve 4, and the electric valve 4 is connected to a top flushing pipe 6; The inlet of the first bypass pipe 7 is connected to a water source, and the outlet is connected to the pipeline between the defogger flushing water pump 3 and the electric valve 4. A power-off self-opening valve A8 is installed on the first bypass pipe 7; The inlet of the second bypass pipe 10 is connected to the pipeline between the defogger flushing water pump 3 and the electric valve 4, and the outlet is connected to the bottom flushing pipe 12. The second bypass pipe 10 is installed with a power-off self-opening valve B9; The top flushing pipe 6 and the bottom flushing pipe 12 are installed on the demister. The top flushing pipe 6 is used to flush the guide vanes, and the bottom flushing pipe 12 is used to flush the bottom of the demister.

[0021] In the embodiment of the present invention, the conventional flushing operation mode is as follows: the defogger flushing water pump 3 is started, the electric valve 4 is opened, the electric valve 4 of the circulation pump is started, the flushing water is pressurized by the defogger flushing water pump 3 and reaches the electric valve 4, and reaches the top flushing pipe 6 through the electric valve 4, and the top flushing pipe 6 flushes the top guide vanes of the tube bundle defogger 14 to prevent the defogger from overheating; Enhanced flushing operation mode: flushing water passes through the demister flushing water pump 3, and after a predetermined time, the electric valve 4 is closed, the power-off self-opening valve B9 automatically opens, and the flushing water passes through the second bypass pipe 10 and the power-off self-opening valve B9 to reach the bottom flushing pipe 12, and the bottom of the tube bundle demister 14 is flushed through the bottom flushing pipe 12 to prevent the bottom of the demister from being blocked and overheated; The desulfurization system operates in the following way when a power failure occurs: When the demister flushing water pump 3 and the electric valve 4 lose power, the power-off self-opening valve A8 and the power-off self-opening valve B9 open automatically, and the flushing water passes through the first bypass pipe 9 and the power-off self-opening valve A8, and then passes through the second bypass pipe 10 to reach the power-off self-opening valve B9, and finally reaches the bottom flushing pipe 12 through the power-off self-opening valve B9, and flushes the bottom of the tube bundle demister 14 through the bottom flushing pipe 12 to prevent the bottom of the demister from being blocked and overheated.

[0022] In the present invention, the inlet of the process water tank 2 is connected to the water inlet pipe 1 , and the outlet is connected to the demister flushing water pump 3 .

[0023] In the embodiment of the present invention, the water source of the process water tank 2 comes from the water treatment workshop of the main plant, and the flushing water enters the process water tank 2 through the water inlet pipe 1. The process water tank 2 is used to store the flushing water.

[0024] In the present invention, the inlet of the automatic backwashing filter 5 is connected to the electric valve 4 , and the outlet is connected to the top flushing pipe 6 .

[0025] In the embodiment of the present invention, the automatic backwash filter 5 is composed of a cylinder, a stainless steel filter, a sewage discharge part, a transmission device and an electrical control part. When the filter is working, the water to be filtered flows through the filter, enters the next required pipeline through the outlet for process circulation, and the particulate impurities in the water are trapped inside the filter. In this continuous cycle, more and more particles are trapped, the filtration speed is getting slower and slower, and the imported sewage still enters continuously, the filter hole will become smaller and smaller, thereby generating a pressure difference between the inlet and outlet. When the pressure difference reaches the set value, the differential pressure transmitter transmits an electrical signal to the controller, and the controller starts the drive motor to drive the shaft to rotate through the transmission component. At the same time, the sewage outlet is opened and discharged from the sewage outlet. When the filter is cleaned, the pressure difference drops to the minimum value, the system returns to the initial filtering state, and the system operates normally.

[0026] In the present invention, the inlet of the Y-type filter 11 is connected to the power-off self-opening valve B9, and the outlet is connected to the bottom flushing pipe 12.

[0027] In the embodiment of the present invention, the Y-type filter 11 is an indispensable filtering device of the pipeline system for conveying the medium, and is used to remove impurities in the medium to protect the normal use of valves and equipment.

[0028] In the present invention, the inlet of the enhanced flushing nozzle 13 is connected to the bottom flushing pipe 12, and the outlet performs enhanced flushing on the bottom of the demister.

[0029] In the embodiment of the present invention, the enhanced flushing nozzle 13 is made of a solid cone of PP material. Compared with ordinary flushing nozzles, this nozzle is a new type of conical spray nozzle with a large spray angle of 60°~170°. It has a smooth channel design, which can achieve the maximum flow rate of liquid on a pipe of a given size and minimize the blockage of the nozzle. Considering a certain degree of flushing overlap and the same flushing coverage, the number of nozzles required to be installed is small, the nozzle installation spacing is large, and maintenance is convenient.

[0030] The present invention also provides a method for enhanced flushing and over-temperature protection flushing of a desulfurization tower tube bundle demister, comprising: Conventional flushing operation mode: start the demister flushing water pump 3, open the electric valve 4, and flush the top of the tube bundle demister 14 through the top flushing pipe 6; Enhanced flushing operation mode: after a predetermined time has passed, the electric valve 4 is closed, the power-off self-opening valve B9 is opened, and the flushing water passes through the first bypass pipe 10 and then through the bottom flushing pipe 12 to flush the bottom of the tube bundle demister 14; Operation mode of power failure of the desulfurization system: When the electric valve 4 is powered off, the power-off self-opening valve B9 opens, and the flushing water enters the second bypass pipe 10 to flush the bottom of the tube bundle demister 14; Operation mode of the desulfurization system in case of power failure: When the demister flushing water pump 3 and the electric valve 4 are powered off, the power-off self-opening valve A8 and the power-off self-opening valve B9 are opened, and the flushing water enters the first bypass pipe 7 and the second bypass pipe 10 to flush the bottom of the tube bundle demister 14.

[0031] In the embodiments of the present invention, the operation modes under different conditions can be realized: Conventional flushing operation mode: control the demister flushing water pump 3 to start, the flushing water is sent to the electric valve 4 through the demister flushing water pump 3, the electric valve 4 is opened, the flushing water is filtered through the automatic backwashing filter 5 and reaches the top flushing pipe 6 to flush the top guide vanes of the tube bundle demister 14; Enhanced flushing operation mode: after a predetermined time, the electric valve 4 is closed, the power-off self-opening valve B9 is automatically opened, and the flushing water passes through the second bypass pipe 10 and the power-off self-opening valve B9 to reach the Y-type filter 11 for filtration, and then passes through the Y-type filter 11 to reach the enhanced flushing nozzle 13 connected to the bottom flushing pipe 12, and the enhanced flushing nozzle 13 performs enhanced flushing on the bottom of the tube bundle demister 14; Circulation pump tripping operation mode: When the circulation pump trips, the electric valve 4 is closed, the power-off self-opening valve B9 is automatically opened, and the flushing water passes through the second bypass pipe 10 and the power-off self-opening valve B9. After being filtered by the filter 11, it reaches the enhanced flushing nozzle 13 connected to the bottom flushing pipe 12. The enhanced flushing nozzle 13 flushes the bottom of the tube bundle demister 14, forming a layer of spray water mist at the bottom of the demister, reducing the hot flue gas temperature to below 80 degrees Celsius, avoiding high-temperature damage to the demister.

[0032] The desulfurization system operates in the following manner when a power failure occurs: when a power failure occurs, the circulating pump stops operating, and the demister flushing water pump 3 also stops operating. The power-off self-opening valve A8 and the power-off self-opening valve B9 open automatically at the same time. The flushing water reaches the first bypass pipe 7 and the power-off self-opening valve A8 through the water inlet pipe 1, and reaches the second bypass pipe 10 and the power-off self-opening valve B9 through the power-off self-opening valve A8. After being filtered by the Y-type filter 11, it reaches the enhanced flushing nozzle 13 connected to the bottom flushing pipe 12. The enhanced flushing nozzle 13 flushes the bottom of the tube bundle demister 14, forming a layer of spray water mist at the bottom of the demister, reducing the hot flue gas temperature to below 80 degrees Celsius, and avoiding high-temperature damage to the demister.

[0033] In the present invention, the pressure during flushing is 0.4-0.5 MPa, and the predetermined interval is 3600-7200 seconds.

[0034] In the present invention, the bottom flushing time is 2 to 4 minutes.

[0035] In the embodiment of the present invention, the desulfurization system has a desulfurization tower diameter of 12.6 m, a total of 13 bottom flushing pipes 12, and each branch pipe is flushed for 3 minutes, which can avoid fouling and scaling at the bottom of the demister.

[0036] In practical applications, the conventional demister bottom enhanced flushing protection method is as follows: a desulfurization system, the desulfurization tower diameter is 12.6m, there are 13 demister flushing branches, the demister flushing water pump flow rate is 130t / h, and the demister flushing water pressure is 0.4~0.5Mpa. Through the automatic control logic, after an interval of 7200s, the electric valve 4 is closed, the power-off self-opening valve B9 is automatically opened, and the water source of the main plant water treatment workshop enters the process water tank 2 through the water inlet pipe 1. The flushing water enters the second bypass pipe 10 and the power-off self-opening valve B9 through the demister flushing water pump 3 to reach the Y-type filter 11. After being filtered by the Y-type filter 11, the flushing water reaches the enhanced flushing nozzle 13 connected to the bottom flushing pipe 12. The enhanced flushing nozzle 13 performs enhanced flushing on the bottom of the tube bundle demister 14, and each branch pipe is flushed for 3 minutes. It can avoid fouling and scaling at the bottom of the demister.

[0037] Over-temperature protection mode during the startup of the standby pump when the circulating pump trips: In a desulfurization system, the flue gas temperature at the inlet of the desulfurization tower is 145℃, the flow rate of the demister water pump is 130t / h, and a single circulating pump trips during operation. The interlocking startup process of the standby pump takes 2.5min. If the time is too long, it is easy to cause over-temperature damage to the demister. When this condition occurs, through the automatic control logic, the power-off self-opening valve B9 is quickly opened within 5 seconds, and the flushing water enters the power-off self-opening valve B9 through the second bypass pipe 10 to reach the Y-type filter 11. After being filtered through the Y-type filter 11, it reaches the enhanced flushing nozzle 13 connected to the bottom flushing pipe 12. The enhanced flushing nozzle 13 performs enhanced flushing on the bottom of the tube bundle demister 14. The flushing water forms a layer of spray water mist at the bottom of the tube bundle demister. The flue gas temperature at the outlet of the desulfurization tower is 75-78℃, which does not exceed the upper limit of the maximum temperature that the demister can withstand, 80℃, which can avoid over-temperature damage to the demister.

[0038] Over-temperature protection method during shutdown of boiler in desulfurization system due to power failure: In a desulfurization system, the flue gas temperature at the inlet of the desulfurization tower is 145℃, the flow rate of the demister water pump is 130t / h, and the desulfurization system loses power. After the circulating pump, air compressor and process water pump in operation trip, the power-off self-opening valve A8 opens quickly within 10 seconds, and the power-off self-opening valve B9 opens quickly within 5 seconds, and the water supply pressure is 0.3-0.35MPa. The flushing water reaches the first bypass pipe 7 and the power-off self-opening valve A8 through the water inlet pipe 1, reaches the second bypass pipe 10 and the power-off self-opening valve B9 through the power-off self-opening valve A8, enters the Y-type filter 11 through the power-off self-opening valve B9, and reaches the enhanced flushing nozzle 13 connected to the bottom flushing pipe 12 after being filtered through the Y-type filter 11. The enhanced flushing nozzle 13 performs enhanced flushing on the bottom of the tube bundle demister 14. The flushing water forms a layer of spray water mist area at the bottom of the tube bundle demister. The flue gas temperature at the outlet of the desulfurization tower is 77-78°C, which does not exceed the maximum temperature upper limit of 80°C that the demister can withstand, and the overall operation time of the automatic spraying system is less than 20 seconds.

[0039] The present invention provides a desulfurization tower tube bundle demister enhanced flushing and over-temperature protection device and method to solve the problem that the bottom of the tube bundle demister cannot be flushed. The enhanced flushing reduces the fouling and clogging at the bottom of the tube bundle demister, ensuring the long-term efficient operation of the demister. At the same time, in the case of a circulating pump trip or system power failure, the high-temperature flue gas is prevented from causing high-temperature damage to the demister, thereby avoiding excessive particulate matter and economic losses.

[0040] The above implementation modes are only used to illustrate the present invention, but not to limit the present invention. Ordinary technicians in the relevant technical field can make various changes and modifications without departing from the spirit and scope of the present invention. Therefore, all equivalent technical solutions also belong to the scope of the present invention. The patent protection scope of the present invention should be defined by the claims.

Claims

1. A desulfurization tower tube bundle demister enhanced flushing and over-temperature protection device, characterized in that: include: A demister flushing water pump (3), a first bypass pipe (7), a second bypass pipe (10), a bottom flushing pipe (12), and a top flushing pipe (6); The inlet of the demister flushing water pump (3) is connected to a water source, and the outlet is connected to an electric valve (4), and the electric valve (4) is connected to a top flushing pipe (6); The inlet of the first bypass pipe (7) is connected to a water source, and the outlet is connected to a pipeline between the demister flushing water pump (3) and the electric valve (4). A power-off self-opening valve A (8) is installed on the first bypass pipe (7); The inlet of the second bypass pipe (10) is connected to the pipeline between the demister flushing water pump (3) and the electric valve (4), and the outlet is connected to the bottom flushing pipe (12). A power-off self-opening valve B (9) is installed on the second bypass pipe (10); The top flushing pipe (6) and the bottom flushing pipe (12) are installed on the demister, the top flushing pipe (6) is used to flush the guide vanes, and the bottom flushing pipe (12) is used to flush the bottom of the demister.

2. A desulfurization tower tube bundle demister enhanced flushing and over-temperature protection device as claimed in claim 1, characterized in that: Also includes: Process water tanks (2); The inlet of the process water tank (2) is connected to the water inlet pipe (1), and the outlet is connected to the demister flushing water pump (3).

3. The enhanced flushing and over-temperature protection device for the desulfurization tower tube bundle demister according to claim 1, characterized in that: Also includes: Automatic backwash filter (5); The inlet of the automatic backwashing filter (5) is connected to the electric valve (4), and the outlet is connected to the top flushing pipe (6).

4. The enhanced flushing and over-temperature protection device for the desulfurization tower tube bundle demister according to claim 1, characterized in that: Also includes: Y-type filter (11); The inlet of the Y-type filter (11) is connected to the power-off self-opening valve B (9), and the outlet is connected to the bottom flushing pipe (12).

5. A desulfurization tower tube bundle demister enhanced flushing and over-temperature protection device according to any one of claims 1 to 4, characterized in that: Also includes: Enhanced flushing nozzles (13); The inlet of the enhanced flushing nozzle (13) is connected to the bottom flushing pipe (12), and the outlet performs enhanced flushing on the bottom of the demister.

6. A method for enhanced flushing and over-temperature protection flushing of a desulfurization tower tube bundle demister, characterized in that: include: Start the demister flushing water pump (3), open the electric valve (4), and flush the top of the tube bundle demister (14) through the top flushing pipe (6); After a predetermined time has passed, the electric valve (4) is closed, the power-off self-opening valve B (9) is opened, and the flushing water passes through the first bypass pipe (10) and then through the bottom flushing pipe (12) to flush the bottom of the tube bundle demister (14); When the electric valve (4) is powered off, the power-off self-opening valve B (9) opens, and flushing water enters the second bypass pipe (10) to flush the bottom of the tube bundle demister (14); When the demister flushing water pump (3) and the electric valve (4) are powered off, the power-off self-opening valve A (8) and the power-off self-opening valve B (9) are opened, and the flushing water enters the first bypass pipe (7) and the second bypass pipe (10) to flush the bottom of the tube bundle demister (14).

7. The method for enhanced flushing and over-temperature protection flushing of the desulfurization tower tube bundle demister according to claim 6, characterized in that: The pressure during flushing is 0.4~0.5Mpa; The predetermined flushing interval is: 3600~7200s.

8. The method for enhanced flushing and over-temperature protection flushing of a desulfurization tower tube bundle demister according to claim 6 or 7, characterized in that: The bottom flushing time is 2 to 4 minutes.

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