CN222069325U - Composite flue gas purifying system with self-cleaning function - Google Patents

Abstract

The utility model belongs to the technical field of flue gas treatment or purification equipment, and specifically relates to a composite flue gas purification system with a self-cleaning function. The composite flue gas purification system with a self-cleaning function includes a packing tower, a first tank filter, and a plate-type dilute acid heat exchanger; the packing tower is provided with an air inlet at the bottom and an exhaust port at the top; the packing tower is provided with a packing layer, a spray pipe, a first high-pressure flushing pipe, a foam catcher, and a second high-pressure flushing pipe from bottom to top; the bottom of the packing tower is connected to a first drain pipe, and a circulating pump is provided on the first drain pipe near the connection with the packing tower. The utility model can achieve the cleaning of the plate-type dilute acid heat exchanger by backwashing with acid or circulating water, and can also flush the foam catcher in the packing tower, so as to avoid the system stopping due to the blockage of the acid or water path in the plate-type dilute acid heat exchanger, or the blockage of the equipment caused by the accumulation of debris in the packing tower.

Description

Composite flue gas purifying system with self-cleaning function

Technical Field

The utility model belongs to the technical field of smoke treatment or purification equipment, and particularly relates to a composite smoke purification system with a self-cleaning function.

Background

The smelting flue gas acid making purifying system relates to purifying towers, drying towers, filling towers and other equipment, and because of the deposition of impurities in flue gas and circulating water in the long-time operation process of various tower equipment, equipment blockage is caused, the operation resistance of the whole system is increased, the heat exchange effect is deteriorated, the energy consumption is increased, the productivity is reduced, and the productivity of enterprises is restricted. Regular shut down of the overall system is required.

In addition, the waterway of the sheet-type dilute acid heat exchanger is cooled by using a water cooling tower, so that the salinity of the waterway is accumulated along with time, and the waterway is easy to crystallize and scale; when the cooling tower is used for cooling the plate type dilute acid heat exchanger, impurities in the environment are easy to enter into a waterway of the plate type dilute acid heat exchanger due to the fact that the cooling tower adopts an unopened cooling mode, phenomena of blockage and plate scaling occur, and the heat exchange effect is poor. If the plate type dilute acid heat exchanger is disassembled and cleaned, the time is long, the gasket is difficult to replace during cleaning, and if the system only has one plate type dilute acid heat exchanger, the plate type dilute acid heat exchanger is cleaned to easily cause the whole system to be stopped, so that the productivity of enterprises is restricted, and the energy consumption and the labor force of personnel are increased.

Meanwhile, in the prior art, no equipment capable of systematically cleaning a packed tower and a sheet type dilute acid heat exchanger exists, and if the equipment is cleaned by manpower, the problems of time consumption, labor consumption and low efficiency are caused.

Therefore, the utility model provides a composite flue gas purification system with a self-cleaning function, which is characterized in that an acid path and a water path in a plate type dilute acid heat exchanger are switched, a dilute acid spray liquid is used for flushing scaling in a water circulation pipeline, so that smoothness of water circulation is realized, acid sludge deposited on the acid circulation pipeline is flushed by utilizing the characteristic of high water pressure, and the problems of blockage of the heat exchanger, a spray head, a foam catcher, a pipeline and the like are effectively solved under the condition that equipment operation is not required to be stopped, so that pump energy consumption, personnel operation difficulty and operation danger are reduced, system operation stop caused by excessive equipment resistance is reduced, and system driving rate is improved.

Disclosure of utility model

Based on the technical problems in the prior art, the utility model provides a composite flue gas purification system with a self-cleaning function, which can realize the switching of an acid path and a water path in a sheet type dilute acid heat exchanger by designing a first pipeline switching structure and a second pipeline switching structure, can realize the cleaning of the sheet type dilute acid heat exchanger by back flushing of acid or circulating water, and can also flush a foam catcher in a packed tower, so that the problem that the system is stopped due to the blockage of the acid path or the water path in the sheet type dilute acid heat exchanger or the blockage of equipment in the packed tower due to sundries is avoided.

Meanwhile, two sets of tank filters are arranged in the utility model, one set is used for standby, and when the resistance of one tank filter is increased, the other set is switched to operate, so that the original tank filter is washed and maintained.

Based on the above purpose, the utility model adopts the following technical scheme:

A composite flue gas purification system with a self-cleaning function comprises a packed tower, a first tank filter and a sheet type dilute acid heat exchanger;

An air inlet is arranged at the lower part of the packed tower the top end is provided with an exhaust port;

A packing layer, a spray pipe, a first high-pressure flushing pipe, a foam catcher and a second high-pressure flushing pipe are sequentially arranged in the packing tower from bottom to top;

the bottom end of the packing tower is connected with a first liquid discharge pipe, a liquid discharge valve is arranged at the joint of the first liquid discharge pipe and the bottom end of the packing tower, and a circulating pump is arranged on the first liquid discharge pipe close to the joint of the first liquid discharge pipe and the packing tower;

the bottom end of the first tank filter is an inlet end, and the top end of the first tank filter is an outlet end;

the first liquid discharge pipe is provided with two branches, namely a first branch and a second branch; the first branch is an acid liquor filtering pipeline, and the inlet end of the first tank filter is communicated with the first branch through a first liquid inlet pipe;

An acid liquor circulation pipeline and a water circulation pipeline are arranged in the sheet type dilute acid heat exchanger, the acid liquor circulation pipeline and the water circulation pipeline are not intersected, and the acid liquor circulation pipeline and the water circulation pipeline are arranged side by side and are used for realizing heat exchange;

The plate type dilute acid heat exchanger is provided with an acid liquor flange inlet A, a circulating water flange outlet B, a circulating water flange inlet C and an acid liquor flange outlet D; an acid liquor flange inlet A is the inlet end of an acid liquor circulation pipeline in the sheet type dilute acid heat exchanger, and an acid liquor flange outlet D is the outlet end of the acid liquor circulation pipeline in the sheet type dilute acid heat exchanger; the circulating water flange inlet C is the inlet end of the water circulating pipeline in the sheet type dilute acid heat exchanger, and the circulating water flange outlet B is the outlet end of the water circulating pipeline in the sheet type dilute acid heat exchanger;

The second branch of the first liquid discharge pipe is an acid liquid inlet pipeline and is communicated with the acid liquid flange inlet A;

The inlet end of the spray pipe extends out of the packing tower, and the acid liquor flange outlet D is communicated with the inlet end of the spray pipe through an acid liquor discharge pipe;

the outlet end of the first tank filter is communicated with the second branch through a second liquid discharge pipe;

A first pipeline switching structure is arranged between the second branch and the circulating water outlet pipe, and a second pipeline switching structure is arranged between the acid liquor outlet pipe and the circulating water inlet pipe;

The circulation switching of the acid liquor circulation pipeline and the water circulation pipeline in the sheet type dilute acid heat exchanger can be realized through the first pipeline switching structure and the second pipeline switching structure, and the acid liquor circulation pipeline or the water circulation pipeline is backwashed.

Further, a first pressure gauge is arranged at the exhaust port.

Further, plastic filler is arranged in the filler layer and used for increasing the contact area between the spray liquid and the smoke.

Further, the foam catcher can adopt a silk screen foam catcher commonly used in the prior art, and has the main functions of removing liquid drops or foam entrained in gas so as to ensure mass transfer efficiency, reduce material loss and improve working conditions of subsequent equipment, and the foam catcher has the diameter of DN6800mm and the thickness of 100-3000mm, can be customized according to the diameter of a packed tower, and can also adopt common models in the prior art.

Further, the side wall of the packing tower is also provided with a second pressure gauge, and the second pressure gauge is positioned below the first high-pressure flushing pipe and above the spray pipe, namely, the second high-pressure flushing pipe, the foam catcher and the first high-pressure flushing pipe are positioned in the packing tower between the first pressure gauge and the second pressure gauge.

Furthermore, the bottom in the packed tower is also filled with water (in addition, acid liquor can be used, and the packed tower is mainly used for adsorbing gases such as sulfur dioxide in high-temperature flue gas, so that the acid liquor can also be sulfuric acid), and the liquid level is lower than the air inlet.

Further, be equipped with first valve on the first feed liquor pipe, be equipped with the third manometer on the position that is close to first feed liquor pipe on the first branch.

Further, the circulating water flange outlet B is communicated with the inlet end of an external circulating water storage device through a circulating water outlet pipe; the circulating water flange inlet C is communicated with the outlet end of the external circulating water storage device through a circulating water inlet pipe.

Further, a second valve is arranged on the second liquid discharge pipe; the bottom end of the first tank filter is also provided with a first flushing end, the first flushing end is connected with a first flushing pipe, and a third valve is arranged on the first flushing pipe; when the first tank filter stops operating, the first valve and the second valve can be closed, the third valve can be opened, the first tank filter is flushed, and acid scale or scale generated by long-time operation is flushed.

Further, fourth valves are arranged on the second branch, at the connection position of the second liquid discharge pipe and the second branch and between the connection position of the second branch and the first branch.

Further preferably, in order to facilitate flushing of the first tank filter, the composite flue gas purifying system with a self-cleaning function further includes a standby tank filter, the standby tank filter and the first tank filter are arranged side by side, and the standby tank filter has the same structure as the first tank filter, namely, the bottom end of the standby tank filter is an inlet end, and the top end of the standby tank filter is an outlet end;

The inlet end of the bottom end of the standby tank filter is communicated with the first branch through a second liquid inlet pipe, and the outlet end of the top end of the standby tank filter is also communicated with the second branch through a third liquid outlet pipe;

the second liquid inlet pipe is provided with a fifth valve, and the third liquid outlet pipe is provided with a sixth valve.

Further, the bottom end of the standby tank filter is also provided with a second flushing end, the second flushing end is connected with a second flushing pipe, and a seventh valve is arranged on the second flushing pipe; similarly, when the standby tank filter stops operating, the fifth valve and the sixth valve can be closed, the seventh valve can be opened, and the standby tank filter can be flushed with acid scale or scale generated by long-time operation.

Still preferably, the first tank filter and the standby tank filter are both internally provided with a wire mesh, so that acid impurities can be filtered, the first tank filter and the standby tank filter are used for one time, when the resistance of one tank filter is increased, the operation is switched to the other operation, and meanwhile, the original tank filter is flushed. Both the first tank filter and the backup tank filter of the present utility model may be provided by conventional means in the art.

Further, a bypass pipe is further arranged on the second branch, and the joint of the bypass pipe and the second branch is positioned at the joint of the third liquid discharge pipe and the second branch and at the joint of the second branch and the acid liquor flange inlet A;

the bypass pipe is provided with two branches, namely a third branch and a fourth branch; the inlet end of the second high-pressure flushing pipe and the inlet end of the first high-pressure flushing pipe extend out of the packing tower, the fourth branch is communicated with the inlet end of the second high-pressure flushing pipe, and the third branch is communicated with the inlet end of the first high-pressure flushing pipe;

The third branch is provided with an eighth valve, and the fourth branch is provided with a ninth valve.

Specifically, the first pipeline switching structure comprises a first communicating pipe, a second communicating pipe, a fourth pressure gauge arranged on the second branch and close to the acid liquor flange inlet A, and a fifth pressure gauge arranged on the circulating water outlet pipe and at the circulating water flange outlet B;

The inlet end of the first communicating pipe and the inlet end of the second communicating pipe are both communicated with the second branch, and the outlet end of the first communicating pipe and the outlet end of the second communicating pipe are both communicated with the circulating water outlet pipe;

The connection part of the inlet end of the second communicating pipe and the second branch is close to the fourth pressure gauge, the connection part of the inlet end of the first communicating pipe and the second branch is far away from the fourth pressure gauge, and a tenth valve is arranged on a pipeline between the connection part of the inlet end of the first communicating pipe and the second branch and the connection part of the inlet end of the second communicating pipe and the second branch;

The connection part of the outlet end of the first communicating pipe and the circulating water outlet pipe is close to the fifth pressure gauge, the connection part of the outlet end of the second communicating pipe and the circulating water outlet pipe is far away from the fifth pressure gauge, and an eleventh valve is arranged on a pipeline between the connection part of the outlet end of the first communicating pipe and the circulating water outlet pipe and the connection part of the outlet end of the second communicating pipe and the circulating water outlet pipe;

the first communicating pipe is provided with a twelfth valve, and the second communicating pipe is provided with a thirteenth valve.

Specifically, the second pipeline switching structure comprises a third communicating pipe, a fourth communicating pipe, a sixth pressure gauge arranged on the circulating water inlet pipe and close to the inlet C of the circulating water flange, and a seventh pressure gauge arranged on the acid liquor discharge pipe and close to the outlet D of the acid liquor flange;

The inlet end of the third communicating pipe and the inlet end of the fourth communicating pipe are both communicated with the circulating water inlet pipe, and the outlet end of the third communicating pipe and the outlet end of the fourth communicating pipe are both communicated with the acid liquor discharge pipe;

The connection part of the inlet end of the third communicating pipe and the circulating water inlet pipe is close to the sixth pressure gauge, the connection part of the inlet end of the fourth communicating pipe and the circulating water inlet pipe is far away from the sixth pressure gauge, and a fourteenth valve is arranged on a pipeline between the connection part of the inlet end of the third communicating pipe and the circulating water inlet pipe and the connection part of the inlet end of the fourth communicating pipe and the circulating water inlet pipe;

The connection part of the outlet end of the fourth communicating pipe and the acid liquor discharge pipe is close to the seventh pressure gauge, the connection part of the outlet end of the third communicating pipe and the acid liquor discharge pipe is far away from the seventh pressure gauge, and a fifteenth valve is arranged on a pipeline between the connection part of the outlet end of the third communicating pipe and the acid liquor discharge pipe and the connection part of the outlet end of the fourth communicating pipe and the acid liquor discharge pipe;

the sixteenth valve is arranged on the third communicating pipe, and the seventeenth valve is arranged on the fourth communicating pipe.

Compared with the prior art, the utility model has the beneficial effects that:

1. The plate type dilute acid heat exchanger is cleaned on line, system stop is not needed, the cleaning liquid is circulation liquid of the plate type dilute acid heat exchanger, and the plate type dilute acid heat exchanger is not required to be disassembled in the cleaning process, so that the system operation is not affected, the disassembly times of the plate type dilute acid heat exchanger are reduced, and meanwhile, the energy consumption of a circulating pump, and the operation difficulty and the operation danger of personnel are reduced.

2. The utility model can effectively solve the problems of scale formation of the water path and blockage of the acid path and the water path inlet in the sheet type dilute acid heat exchanger, reduces the running resistance of the sheet type dilute acid heat exchanger and the energy consumption of the circulating pump, and further ensures the heat exchange effect of the sheet type dilute acid heat exchanger.

3. According to the utility model, the scale in the water circulation pipeline is washed by using the dilute acid spray liquid by switching the acid path and the water path in the plate type dilute acid heat exchanger, so that the smoothness of water circulation is realized, and the acid mud deposited on the acid circulation pipeline is washed by using the characteristic of high water pressure, so that the problem of blockage of auxiliary equipment of a packing tower such as the plate type dilute acid heat exchanger is effectively solved, the shutdown of the whole system is avoided, the energy consumption is increased, and the productivity is reduced.

4. The tank filter provided by the utility model can filter and deposit acid road mud, prevent spray blockage, and simultaneously can flush the acid road mud, reduce the increase of resistance of equipment caused by blockage, and stop the system.

5. According to the utility model, the pipeline pressure and whether the pipeline is blocked or not can be judged according to the pressure difference between the pressure gauges, when the pressure difference rises, the blocking condition of the waterway or the acid circuit is indicated, and the waterway or the acid circuit can be switched and flushed in time according to the production condition; and after the pressure difference is recovered to be normal, the pressure difference is switched to the original running state again.

6. The utility model can effectively solve the problem of blockage in the packed tower, the first tank filter and the sheet type dilute acid heat exchanger, has high automation degree, reduces the workload of manual cleaning operation during maintenance, reduces the working intensity of operators, reduces the working time of the operators under acidic liquid, and reduces the risk of occurrence of safety events.

Drawings

Fig. 1 is a schematic structural diagram of a composite flue gas purifying system with a self-cleaning function according to embodiment 1;

FIG. 2 is a right side view of the plate-type dilute acid heat exchanger;

FIG. 3 is a front view of the plate-type dilute acid heat exchanger;

FIG. 4 is a flow chart of the first pipeline switching structure;

FIG. 5 is a flow chart of the pipeline switching structure of the second pipeline switching structure;

Wherein: 1. a packing tower, 11, a packing layer, 12, a spray pipe, 13, a first high-pressure flushing pipe, 14, a foam catcher, 15, a second high-pressure flushing pipe, 16, a circulating pump, 17, a first branch, 18, a second branch, 181, a fourth valve, 182, a third branch, 183, a fourth branch, 184, an eighth valve, 185, a ninth valve, 186 and a tenth valve;

2. A first tank filter 21, a first valve 22, a second valve 23 and a third valve;

3. A plate dilute acid heat exchanger 31, an acid liquor discharge pipe 32 and a fifteenth valve;

4. a standby tank filter 41, a fifth valve 42, a sixth valve 43 and a seventh valve;

51. A circulating water outlet pipe 52, a circulating water inlet pipe 53, an eleventh valve 54 and a fourteenth valve;

6. a first communication pipe 61 and a twelfth valve;

7. A second communication pipe 71, a thirteenth valve;

8. a third communication pipe 81, a sixteenth valve;

9. A fourth communication pipe, 91, seventeenth valve;

101. First pressure gauge 102, second pressure gauge 103, third pressure gauge 104, fourth pressure gauge 105, fifth pressure gauge 106, sixth pressure gauge 107, seventh pressure gauge.

Detailed Description

For an understanding of the present utility model, reference will now be made in detail to the present utility model, examples of which are illustrated in the accompanying drawings and described in the preferred embodiments, but the scope of the utility model is not limited to the specific embodiments.

Unless defined otherwise, all technical and scientific terms used hereinafter have the same meaning as commonly understood by one of ordinary skill in the art. The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the scope of the present utility model.

Unless otherwise specifically indicated, the various raw materials, reagents, instruments, equipment and the like used in the present utility model are commercially available or may be prepared by existing methods.

Example 1

As shown in fig. 1-5, a composite flue gas purification system with a self-cleaning function comprises a packed tower 1, a first tank filter 2 and a sheet dilute acid heat exchanger 3;

The lower part of the packed tower 1 is provided with an air inlet, the top end of the packed tower is provided with an air outlet, and the air outlet is provided with a first pressure gauge 101;

A packing layer 11, a spray pipe 12, a first high-pressure flushing pipe 13, a foam catcher 14 and a second high-pressure flushing pipe 15 are sequentially arranged in the packing tower 1 from bottom to top; plastic filler is arranged in the filler layer 11 and used for increasing the contact area between the spray liquid and the flue gas;

The foam catcher 14 can be a silk screen foam catcher commonly used in the prior art, and has the main functions of removing liquid drops or foam entrained in gas, ensuring mass transfer efficiency, reducing material loss and improving working conditions of subsequent equipment, wherein the diameter of the foam catcher 14 is DN6800mm, the thickness is 100-3000mm, the foam catcher can be customized according to the diameter of a packed tower 1, and the foam catcher can also be a common model in the prior art, and the structure is not the utility model point of the utility model, so that repeated description is omitted;

The side wall of the packing tower 1 is also provided with a second pressure gauge 102, the second pressure gauge 102 is positioned below the first high-pressure flushing pipe 13 and above the spray pipe 12, namely, the second high-pressure flushing pipe 15, the foam catcher 14 and the first high-pressure flushing pipe 13 are positioned in the packing tower 1 between the first pressure gauge 101 and the second pressure gauge 102;

The bottom in the packed tower 1 is also filled with water (in addition, acid liquor can be used, and the packed tower 1 is mainly used for adsorbing gases such as sulfur dioxide in high-temperature flue gas, and the like, so that the acid liquor can also be sulfuric acid), and the liquid level is lower than the air inlet.

The bottom end of the packing tower 1 is connected with a first liquid discharge pipe, a liquid discharge valve is arranged at the joint of the first liquid discharge pipe and the bottom end of the packing tower 1, and a circulating pump 16 is arranged on the first liquid discharge pipe near the joint of the first liquid discharge pipe and the packing tower 1;

The bottom end of the first tank filter 2 is an inlet end, and the top end is an outlet end;

The first liquid discharge pipe is provided with two branches, namely a first branch 17 and a second branch 18; the first branch 17 is an acid liquor filtering pipeline, the inlet end of the first tank filter 2 is communicated with the first branch 17 through a first liquid inlet pipe, a first valve 21 is arranged on the first liquid inlet pipe, and a third pressure gauge 103 is arranged on the first branch 17 and close to the first liquid inlet pipe.

An acid liquor circulation pipeline and a water circulation pipeline are arranged in the sheet type dilute acid heat exchanger 3, the acid liquor circulation pipeline and the water circulation pipeline are not intersected, and the acid liquor circulation pipeline and the water circulation pipeline are arranged side by side and are used for realizing heat exchange, namely, the circulating water in the water circulation pipeline can exchange heat with the acid liquor in the acid liquor circulation pipeline, and the acid liquor in the acid liquor circulation pipeline is cooled;

Specifically, the plate-type dilute acid heat exchanger 3 is conventional equipment, and the utility model mainly explains the pipeline connection relation between the plate-type dilute acid heat exchanger 3 and the packing tower 1 and the first tank filter 2, and the structure and the model of the plate-type dilute acid heat exchanger are all achieved by adopting conventional technical means in the field and are not the utility model point of the utility model, so that the description is omitted;

As shown in fig. 3, a schematic diagram of a main working surface of the plate-type dilute acid heat exchanger 3 according to the present utility model is shown, wherein the main working surface of the plate-type dilute acid heat exchanger 3 is provided with an acid liquor flange inlet a, a circulating water flange outlet B, a circulating water flange inlet C, and an acid liquor flange outlet D; the inlet A of the acid liquor flange is the inlet end of the acid liquor circulation pipeline in the sheet type dilute acid heat exchanger 3, and the outlet D of the acid liquor flange is the outlet end of the acid liquor circulation pipeline in the sheet type dilute acid heat exchanger 3; the circulating water flange inlet C is the inlet end of the water circulation pipeline in the sheet type dilute acid heat exchanger 3, and the circulating water flange outlet B is the outlet end of the water circulation pipeline in the sheet type dilute acid heat exchanger 3;

The second branch 18 of the first liquid discharge pipe is an acid liquid inlet pipe, and the second branch 18 is communicated with the acid liquid flange inlet A.

As shown in fig. 4 and 5, the circulating water flange outlet B is communicated with the inlet end of the external circulating water storage device through a circulating water outlet pipe 51; the circulating water flange inlet C is communicated with the outlet end of an external circulating water storage device through a circulating water inlet pipe 52;

The inlet end of the spray pipe 12 extends out of the packed tower 1, and the acid liquor flange outlet D is communicated with the inlet end of the spray pipe 12 through an acid liquor discharge pipe 31;

The outlet end of the first tank filter 2 is communicated with a second branch 18 through a second liquid discharge pipe, and a second valve 22 is arranged on the second liquid discharge pipe; the bottom end of the first tank filter 2 is also provided with a first flushing end, the first flushing end is connected with a first flushing pipe, and a third valve 23 is arranged on the first flushing pipe; when the first tank filter 2 stops operating, the first valve 21 and the second valve 22 can be closed, the third valve 23 can be opened, the first tank filter 2 is flushed, and acid scale or scale generated by long-time operation is flushed;

A fourth valve 181 is arranged on the second branch 18, at the junction of the second liquid discharge pipe and the second branch 18, and between the junction of the second branch 18 and the first branch 17.

Further preferably, in order to facilitate flushing the first tank filter 2, the utility model further comprises a standby tank filter 4, wherein the standby tank filter 4 is arranged side by side with the first tank filter 2, and the standby tank filter 4 has the same structure as the first tank filter 2, namely, the bottom end of the standby tank filter 4 is an inlet end, and the top end is an outlet end;

The inlet end of the bottom end of the standby tank filter 4 is communicated with the first branch 17 through a second liquid inlet pipe, and the outlet end of the top end of the standby tank filter 4 is also communicated with the second branch 18 through a third liquid outlet pipe;

a fifth valve 41 is arranged on the second liquid inlet pipe, and a sixth valve 42 is arranged on the third liquid outlet pipe;

The bottom end of the standby tank filter 4 is also provided with a second flushing end, the second flushing end is connected with a second flushing pipe, and a seventh valve 43 is arranged on the second flushing pipe; similarly, when the operation of the spare tank filter 4 is stopped, the fifth valve 41 and the sixth valve 42 may be closed, the seventh valve 43 may be opened, and the spare tank filter 4 may be rinsed, and the scale or scale generated due to the long-term operation may be rinsed.

The inside silk screen that all is equipped with of first tank filter 2 and reserve tank filter 4 can filter sour way impurity, and first tank filter 2 and reserve tank filter 4 are reserve, when one of them tank filter resistance increases, switch into another operation, wash former tank filter simultaneously. The first tank filter 2 and the spare tank filter 4 in the present utility model are all conventional apparatuses in the art, and the structure thereof is not the point of the present utility model, so that the description thereof is omitted.

Further, a bypass pipe is further arranged on the second branch 18, and the joint of the bypass pipe and the second branch 18 is positioned at the joint of the third liquid discharge pipe and the second branch 18 and at the joint of the second branch 18 and the acid liquor flange inlet A;

The bypass tube is provided with two branches, a third branch 182 and a fourth branch 183, respectively; the inlet end of the second high-pressure flushing pipe 15 and the inlet end of the first high-pressure flushing pipe 13 extend out of the packed tower 1, a fourth branch 183 is communicated with the inlet end of the second high-pressure flushing pipe 15, and a third branch 182 is communicated with the inlet end of the first high-pressure flushing pipe 13;

The third branch 182 is provided with an eighth valve 184, and the fourth branch 183 is provided with a ninth valve 185.

As shown in fig. 4 and 5, a first pipeline switching structure is arranged between the second branch 18 and the circulating water outlet pipe 51, and a second pipeline switching structure is arranged between the acid liquor outlet pipe 31 and the circulating water inlet pipe 52;

Specifically, the first pipeline switching structure includes a first communicating pipe 6, a second communicating pipe 7, a fourth pressure gauge 104 disposed on the second branch 18 near the acid liquor flange inlet a, and a fifth pressure gauge 105 disposed on the circulating water outlet pipe 51 at the circulating water flange outlet B;

The inlet end of the first communicating pipe 6 and the inlet end of the second communicating pipe 7 are both communicated with the second branch 18, and the outlet end of the first communicating pipe 6 and the outlet end of the second communicating pipe 7 are both communicated with the circulating water outlet pipe 51;

The connection part of the inlet end of the second communicating pipe 7 and the second branch 18 is close to the fourth pressure gauge 104, the connection part of the inlet end of the first communicating pipe 6 and the second branch 18 is far away from the fourth pressure gauge 104, and a tenth valve 186 is arranged on a pipeline between the connection part of the inlet end of the first communicating pipe 6 and the second branch 18 and the connection part of the inlet end of the second communicating pipe 7 and the second branch 18;

the connection part of the outlet end of the first communication pipe 6 and the circulating water outlet pipe 51 is close to the fifth pressure gauge 105, the connection part of the outlet end of the second communication pipe 7 and the circulating water outlet pipe 51 is far away from the fifth pressure gauge 105, and an eleventh valve 53 is arranged on a pipeline between the connection part of the outlet end of the first communication pipe 6 and the circulating water outlet pipe 51 and the connection part of the outlet end of the second communication pipe 7 and the circulating water outlet pipe 51;

The twelfth valve 61 is provided in the first communication pipe 6, and the thirteenth valve 71 is provided in the second communication pipe 7.

Specifically, the second pipeline switching structure includes a third communicating pipe 8, a fourth communicating pipe 9, a sixth pressure gauge 106 disposed on the circulating water inlet pipe 52 near the inlet C of the circulating water flange, and a seventh pressure gauge 107 disposed on the acid liquid outlet pipe 31 near the outlet D of the acid liquid flange;

The inlet end of the third communicating pipe 8 and the inlet end of the fourth communicating pipe 9 are both communicated with the circulating water inlet pipe 52, and the outlet end of the third communicating pipe 8 and the outlet end of the fourth communicating pipe 9 are both communicated with the acid liquor discharge pipe 31;

The connection between the inlet end of the third communicating pipe 8 and the circulating water inlet pipe 52 is close to the sixth pressure gauge 106, the connection between the inlet end of the fourth communicating pipe 9 and the circulating water inlet pipe 52 is far away from the sixth pressure gauge 106, and a fourteenth valve 54 is arranged on the pipeline between the connection between the inlet end of the third communicating pipe 8 and the circulating water inlet pipe 52 and the connection between the inlet end of the fourth communicating pipe 9 and the circulating water inlet pipe 52;

The joint of the outlet end of the fourth communicating pipe 9 and the acid liquid discharge pipe 31 is close to the seventh pressure gauge 107, the joint of the outlet end of the third communicating pipe 8 and the acid liquid discharge pipe 31 is far away from the seventh pressure gauge 107, and a fifteenth valve 32 is arranged on a pipeline between the joint of the outlet end of the third communicating pipe 8 and the acid liquid discharge pipe 31 and the joint of the outlet end of the fourth communicating pipe 9 and the acid liquid discharge pipe 31;

The sixteenth valve 81 is provided in the third communication pipe 8, and the seventeenth valve 91 is provided in the fourth communication pipe 9.

The operation principle of the utility model is as follows:

1. the flue gas purifying process comprises the following steps: in the process, high-temperature acid-containing flue gas firstly enters from the air inlet of the packed tower 1 and then flows upwards, at the moment, a liquid discharge valve and a circulating pump 16 are opened, water (or acid liquor) at the inner bottom of the packed tower 1 is discharged from a first liquid discharge pipe to be used as spray liquid, at the moment, a fourth valve 181, a third valve 23, a fifth valve 41, a sixth valve 42, a seventh valve 43, an eighth valve 184, a ninth valve 185, a twelfth valve 61, a thirteenth valve 71, a sixteenth valve 81 and a seventeenth valve 91 are closed;

Opening the first valve 21, the second valve 22, the tenth valve 186, the eleventh valve 53, the fourteenth valve 54, the fifteenth valve 32;

The spray liquid firstly enters from the inlet end of the lower end of the first tank filter 2 and is discharged from the outlet end of the top end, the first tank filter 2 is internally provided with silk screens through which impurities of the spray liquid can be filtered, the filtered spray liquid enters into an acid liquid circulation pipeline in the sheet type dilute acid heat exchanger 3 from an acid liquid flange inlet A through a second branch 18, at the moment, cooling circulating water enters into a water circulation pipeline in the sheet type dilute acid heat exchanger 3 from a circulating water flange inlet C through a circulating water inlet pipe 52 from an external circulating water storage device, and heat exchange and cooling are carried out on the spray liquid in the acid liquid circulation pipeline through cooling circulating water;

The cooled spray liquid is discharged from the acid liquor flange outlet D, enters the spray pipe 12 through the acid liquor discharge pipe 31, is sprayed from the spray pipe 12, enters the packing layer 11 to be contacted with the rising high-temperature acid-containing flue gas, adsorbs gases such as sulfur dioxide and the like in the gas, realizes the purification of the gas, and the purified gas continuously rises;

Meanwhile, the cooling circulating water after heat exchange is discharged from the circulating water flange outlet B and enters the external circulating water storage device again through the circulating water outlet pipe 51 for recycling.

2. Back cleaning process of the plate type dilute acid heat exchanger 3: when the system runs for a period of time, scale or other impurities in cooling circulating water can remain in the water circulation pipeline of the plate-type dilute acid heat exchanger 3, so that the pipeline is blocked, meanwhile, the condition that impurities in spray liquid (acid liquid) are blocked in the acid liquid circulation pipeline is also possible, at the moment, scaling in the water circulation pipeline is washed by using dilute acid spray liquid by regulating and controlling a first pipeline switching structure and a second pipeline switching structure, and the water circulation is smooth; the specific regulation and control are as follows:

When the pressure difference between the fifth pressure gauge 105 and the sixth pressure gauge 106 is excessively increased, or the pressure difference between the fourth pressure gauge 104 and the seventh pressure gauge 107 is excessively increased, it is indicated that a blockage occurs in the water circulation line or the acid circulation line of the plate-type dilute acid heat exchanger 3, and at this time, the fourth valve 181, the third valve 23, the eighth valve 184, the ninth valve 185, the sixth valve 42 of the fifth valve 41, the seventh valve 43, the tenth valve 186, the eleventh valve 53, the fourteenth valve 54, and the fifteenth valve 32 are closed;

At the same time, the drain valve, the circulation pump 16, the first valve 21, the second valve 22, the twelfth valve 61, the thirteenth valve 71, the sixteenth valve 81, the seventeenth valve 91 are opened;

at this time, as shown in fig. 4 and 5, the spray liquid entering the second branch 18 enters from the inlet end of the first communication pipe 6, flows into the circulating water outlet pipe 51, reversely enters into the water circulation pipeline of the plate-type dilute acid heat exchanger 3 from the circulating water flange outlet B, reversely flows out from the circulating water flange inlet C, and uses the corrosiveness of acid to realize back flushing of the water circulation pipeline and corrosion of scale;

After flowing out from the inlet C of the circulating water flange, the spray liquid enters an acid liquid discharge pipe 31 through a third communicating pipe 8, enters a spray pipe 12, is sprayed out of the spray pipe 12, and is collected at the bottom of the packing tower 1;

Meanwhile, cooling circulating water sequentially passes through the circulating water inlet pipe 52, the fourth communicating pipe 9 and the acid liquor discharge pipe 31 from the external circulating water storage device, reversely enters the acid liquor circulating pipeline of the sheet type dilute acid heat exchanger 3 from the acid liquor flange outlet D, and backflushes and brings out a blockage in the acid liquor circulating pipeline by using the cooling circulating water, and reversely flows out from the acid liquor flange inlet A;

After flowing out from the acid liquor flange inlet A, the cooling circulating water enters the circulating water outlet pipe 51 through the second communicating pipe 7, and enters the external circulating water storage device again through the circulating water outlet pipe 51 for recycling.

When the differential pressure displayed by the fifth pressure gauge 105 and the sixth pressure gauge 106 or the differential pressure displayed by the fourth pressure gauge 104 and the seventh pressure gauge 107 recovers to the original differential pressure, the impurity and the scale are completely washed, and the operation mode can be switched to the original valve operation mode again, so that the flue gas purification process is performed.

3. Maintenance and cleaning process of the first tank filter 2: when the system runs for a period of time and the flow resistance occurs in the first tank filter 2 due to the existence of some impurities in the spray liquid (acid liquid), the first tank filter 2 is cleaned and maintained through the switching of pipelines among the packed tower 1, the first tank filter 2, the standby tank filter 4 and the sheet dilute acid heat exchanger 3; the specific operation is as follows:

When the differential pressure shown by the fourth pressure gauge 104 and the third pressure gauge 103 increases too much, it indicates that a blockage occurs in the first tank filter 2, and at this time, the first valve 21, the second valve 22, the third valve 23, the eighth valve 184, the ninth valve 185, the fifth valve 41, the sixth valve 42, and the seventh valve 43 are closed;

Opening the drain valve, the circulation pump 16, the fourth valve 181, the tenth valve 186, the eleventh valve 53, the fourteenth valve 54, the fifteenth valve 32;

The spray liquid sequentially passes through the second branch 18 and the acid liquor flange inlet A and enters the sheet dilute acid heat exchanger 3 to carry out the normal flue gas purification process.

In addition, when the differential pressure shown by the fourth pressure gauge 104 and the third pressure gauge 103 increases too much, the drain valve, the circulation pump 16, the fifth valve 41, the sixth valve 42, the tenth valve 186, the eleventh valve 53, the fourteenth valve 54, the fifteenth valve 32 may also be opened;

The fourth valve 181, the first valve 21, the second valve 22, the third valve 23 and the seventh valve 43 are closed, and the standby tank filter 4 is used for replacing the first tank filter 2, so that the impurity removal and filtration of the spray liquid (acid liquid) are realized, and meanwhile, the first tank filter 2 is maintained and cleaned.

4. The cleaning process of the foam catcher 14: since a small amount of impurities may remain in the flue gas when the flue gas rises to the position of the foam trap 14, after the system is operated for a period of time, the foam trap 14 is blocked by excessive impurities, at this time, the pressure difference between 13 and the exhaust port of the packed tower 1 is detected by the first pressure gauge 101 and the second pressure gauge 102, and when the pressure difference displayed by the first pressure gauge 101 and the second pressure gauge 102 rises too much, the foam trap 14 is blocked, and at this time, the liquid discharge valve, the circulating pump 16, the first valve 21, the second valve 22, the eighth valve 184 and the ninth valve 185 are opened;

Closing the tenth valve 186, the third valve 23, the fifth valve 41, the sixth valve 42, the seventh valve 43; at this time, the spray liquid passes through the second branch 18, the third branch 182, and the fourth branch 183 in this order, and is discharged from the first high-pressure flushing pipe 13 and the second high-pressure flushing pipe 15, thereby flushing the foam trap 14.

In the utility model, all valves are made of acid corrosion resistant materials, so that equipment corrosion is prevented, in addition, in order to improve the automation degree of the whole system, all valves can be made of electric acid resistant valves, and can also be controlled by interlocking through a DCS system, and a specific electric control mode is not the utility model point of the utility model, so that the utility model is not repeated.

According to the utility model, the second high-pressure flushing pipe 15 and the first high-pressure flushing pipe 13 are respectively arranged at the upper part of the packed tower 1 and above and below the foam catcher 14, so that when the resistance of the foam catcher 14 is increased, the foam catcher 14 in the packed tower 1 can be regularly reversely flushed, and the equipment blockage caused by sundries accumulation is reduced.

The first liquid discharge pipe of the packing tower 1 is provided with a circulating pump 16, so that spray liquid (acid liquid) in the packing tower 1 can be pumped out and enter the first tank filter 2, and when flow resistance occurs in the first tank filter 2, the spray liquid is switched to the standby tank filter 4 to operate through pipeline switching among the packing tower 1, the first tank filter 2, the standby tank filter 4 and the sheet dilute acid heat exchanger 3, and meanwhile, the first tank filter 2 is cleaned and maintained.

When resistance of a water circulation pipeline or an acid circulation pipeline in the sheet dilute acid heat exchanger 3 is increased, the water circulation pipeline and the acid circulation pipeline can be directly switched and operated by regulating and controlling the first pipeline switching structure and the second pipeline switching structure, a valve is used for switching, a raw water pipeline is changed into an acid pipeline, an original pipeline is changed into a waterway, scaling in the water circulation pipeline is washed by dilute acid spray liquid, so that smoothness of water circulation is realized, acid mud deposited in the acid circulation pipeline is washed by utilizing the characteristic of high water pressure, an original inlet is changed into an outlet, and an original outlet is changed into an inlet to perform back washing on the original inlet of the sheet dilute acid heat exchanger 3.

The utility model also adds pressure gauges above and below the foam catcher 14, at the inlet and outlet of the water circulation pipeline or the acid liquid circulation pipeline of the sheet type dilute acid heat exchanger 3 and at the inlet and outlet of the first tank filter 2, and timely judges the blocking condition in each device by detecting the pressure difference change, thereby being convenient for guiding the switching time of the valve and ensuring the normal operation of the device.

In addition, in the back cleaning process of the sheet type dilute acid heat exchanger 3, external cleaner acid liquor can be used, so that the flushing effect is improved, and no redundant water is fed into the system at the moment, so that the water balance of the system is achieved.

The utility model discloses a composite flue gas purification system with a self-cleaning function, and aims to solve the problems that in a smelting flue gas acid production purification system used in a smelting flue gas treatment process, a pipeline of a sheet type dilute acid heat exchanger 3 is blocked when dilute acid or circulating water exchanges heat, or the inside of a packed tower 1 is blocked or a packing is scaled due to acid liquor spraying.

The utility model solves the problems of scaling and blockage of the acid path or the waterway of the sheet type dilute acid heat exchanger 3, blockage of spraying equipment, blockage of a foam catcher and the like in the existing production process to a certain extent by adopting the technical means of pressure detection, pipeline switching, flushing and the like; the problems of high operation difficulty, high production energy consumption, productivity restriction and the like of personnel caused by the increase of running resistance and the deterioration of heat exchange effect due to equipment blockage are avoided. Meanwhile, the disassembly times of the sheet type dilute acid heat exchanger 3, the equipment shutdown time and the shutdown maintenance time can be reduced.

The system disclosed by the utility model can monitor the pressure difference between the inlet and the outlet of the equipment in real time, the materials of the pipelines in the whole system are connected by adopting acid-resistant materials, corrosion is prevented, and meanwhile, detection components such as a pressure gauge and the like can be detected on line and displayed on site. The utility model can realize the online cleaning of the packed tower 1 and the accessory equipment thereof, and does not influence the normal operation of the whole system.

The system provided by the utility model has the advantages of simple structure and convenience in operation, and can be suitable for cleaning and maintaining various smelting flue gas systems.

Application example 1

Taking a certain copper smelting production enterprise as an example, the flue gas generated by the copper smelting furnace is cooled by a waste heat boiler, the flue gas enters an acid making section after being collected by an electric dust collector and a bag-type dust collector, and the flue gas enters a packing tower 1 for continuous cooling and dust removal after being cooled and dust removed by primary dynamic waves and then enters secondary dynamic cooling and dust removal. At the moment, heat is accumulated in the packed tower 1 and needs to be carried out by circulating water through the sheet type dilute acid heat exchanger 3;

The original design plate type dilute acid heat exchanger 3 is provided with two open-one-standby-type dilute acid heat exchangers, three-channel-type dilute acid heat exchangers are simultaneously opened after the heat exchange effect is poor, the foam catcher 14 is blocked, the system is required to be washed after the system stops running, a spray head of the spraying system is blocked by a filler layer 11 to be hardened due to impurity aggregation, and when the heat exchange effect of the plate type dilute acid heat exchanger 3 is poor, the system is required to be disconnected for disassembly and cleaning; however, with the lapse of time, the running frequency of the circulating water pump 16 is increased, the energy consumption is increased, the acid sludge at the bottom of the tower body is deposited, and the maintenance, the cleaning and the maintenance are required to be stopped.

After transformation, by adopting the composite flue gas purification system with the self-cleaning function, the plate-type dilute acid heat exchanger 3 is restored to the original design two-on-one-standby state, the foam catcher 14 can be cleaned on line, the system operation time is prolonged, the maintenance times are reduced, the driving rate is increased, meanwhile, the pump energy consumption is reduced, the cost is reduced, and the operation is stable.

In the description of the present utility model, it should be noted that, for the azimuth words such as "center", "lateral", "longitudinal", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", etc., the azimuth and positional relationships are based on the azimuth or positional relationships shown in the drawings, it is merely for convenience of describing the present utility model and simplifying the description, and it is not to be construed as limiting the specific protection scope of the present utility model by indicating or implying that the apparatus or element to be referred to must have a specific azimuth configuration and operation.

It should be noted that the terms "first," "second," and the like in the description and in the claims are used for distinguishing between similar objects and not necessarily for describing a particular sequential or chronological order. It is to be understood that the data so used may be interchanged where appropriate in order to describe the embodiments of the application herein. Furthermore, the terms "comprises," "comprising," and "having," and any variations thereof, are intended to cover a non-exclusive inclusion, such that a process, method, system, article, or apparatus that comprises a list of steps or elements is not necessarily limited to those steps or elements expressly listed but may include other steps or elements not expressly listed or inherent to such process, method, article, or apparatus.

Finally, what should be said is: the foregoing description is only of the preferred embodiments of the utility model and the application of the principles of the utility model. It will be understood by those skilled in the art that the present utility model is not limited to the particular embodiments described herein, but is capable of various obvious changes, rearrangements and substitutions as will now become apparent to those skilled in the art without departing from the scope of the utility model. Therefore, while the present utility model has been described in connection with the above embodiments, it is to be understood that the utility model is not limited to the specific embodiments disclosed and that many other and equally effective embodiments may be devised without departing from the basic scope thereof, and the scope thereof is determined by the claims that follow.

Claims (10)

1. The composite flue gas purification system with the self-cleaning function is characterized by comprising a packed tower, a first tank filter and a sheet type dilute acid heat exchanger;

An air inlet is arranged at the lower part of the packed tower the top end is provided with an exhaust port;

A packing layer, a spray pipe, a first high-pressure flushing pipe, a foam catcher and a second high-pressure flushing pipe are sequentially arranged in the packing tower from bottom to top;

the bottom end of the packing tower is connected with a first liquid discharge pipe, a liquid discharge valve is arranged at the joint of the first liquid discharge pipe and the bottom end of the packing tower, and a circulating pump is arranged on the first liquid discharge pipe close to the joint of the first liquid discharge pipe and the packing tower;

the bottom end of the first tank filter is an inlet end, and the top end of the first tank filter is an outlet end;

the first liquid discharge pipe is provided with two branches, namely a first branch and a second branch; the first branch is an acid liquor filtering pipeline, and the inlet end of the first tank filter is communicated with the first branch through a first liquid inlet pipe;

An acid liquor circulation pipeline and a water circulation pipeline are arranged in the sheet type dilute acid heat exchanger, the acid liquor circulation pipeline and the water circulation pipeline are not intersected, and the acid liquor circulation pipeline and the water circulation pipeline are arranged side by side and are used for realizing heat exchange;

The plate type dilute acid heat exchanger is provided with an acid liquor flange inlet A, a circulating water flange outlet B, a circulating water flange inlet C and an acid liquor flange outlet D; an acid liquor flange inlet A is the inlet end of an acid liquor circulation pipeline in the sheet type dilute acid heat exchanger, and an acid liquor flange outlet D is the outlet end of the acid liquor circulation pipeline in the sheet type dilute acid heat exchanger; the circulating water flange inlet C is the inlet end of the water circulating pipeline in the sheet type dilute acid heat exchanger, and the circulating water flange outlet B is the outlet end of the water circulating pipeline in the sheet type dilute acid heat exchanger;

The second branch of the first liquid discharge pipe is an acid liquid inlet pipeline and is communicated with the acid liquid flange inlet A;

The inlet end of the spray pipe extends out of the packing tower, and the acid liquor flange outlet D is communicated with the inlet end of the spray pipe through an acid liquor discharge pipe;

the outlet end of the first tank filter is communicated with the second branch through a second liquid discharge pipe;

A first pipeline switching structure is arranged between the second branch and the circulating water outlet pipe, and a second pipeline switching structure is arranged between the acid liquor outlet pipe and the circulating water inlet pipe;

The circulation switching of the acid liquor circulation pipeline and the water circulation pipeline in the sheet type dilute acid heat exchanger can be realized through the first pipeline switching structure and the second pipeline switching structure, and the acid liquor circulation pipeline or the water circulation pipeline is backwashed.

2. The composite flue gas purification system with a self-cleaning function according to claim 1, wherein a first pressure gauge is arranged at the exhaust port; the side wall of the packed tower is also provided with a second pressure gauge, and the second pressure gauge is positioned below the first high-pressure flushing pipe and above the spraying pipe.

3. The composite flue gas purification system with a self-cleaning function according to claim 1, wherein the first liquid inlet pipe is provided with a first valve, and the first branch is provided with a third pressure gauge at a position close to the first liquid inlet pipe.

4. The composite flue gas purification system with the self-cleaning function according to claim 1, wherein a second valve is arranged on the second liquid discharge pipe; the bottom of first tank filter still is equipped with first washing end, and first washing end is connected with first flushing pipe, is equipped with the third valve on the first flushing pipe.

5. The composite flue gas purifying system with a self-cleaning function according to claim 1, wherein a fourth valve is provided on the second branch, at a junction of the second liquid discharge pipe and the second branch, and between the junction of the second branch and the first branch.

6. The composite flue gas purifying system with a self-cleaning function according to claim 1, further comprising a standby tank filter, wherein the standby tank filter is arranged side by side with the first tank filter, the bottom end of the standby tank filter is an inlet end, and the top end of the standby tank filter is an outlet end;

The inlet end of the bottom end of the standby tank filter is communicated with the first branch through a second liquid inlet pipe, and the outlet end of the top end of the standby tank filter is also communicated with the second branch through a third liquid outlet pipe;

the second liquid inlet pipe is provided with a fifth valve, and the third liquid outlet pipe is provided with a sixth valve.

7. The composite flue gas purification system with a self-cleaning function according to claim 6, wherein the bottom end of the standby tank filter is further provided with a second flushing end, the second flushing end is connected with a second flushing pipe, and a seventh valve is arranged on the second flushing pipe.

8. The composite flue gas purification system with the self-cleaning function according to claim 1, wherein a bypass pipe is further arranged on the second branch, and the connection part of the bypass pipe and the second branch is positioned at the connection part of the third liquid discharge pipe and the second branch and at the connection part of the second branch and the acid liquor flange inlet A;

the bypass pipe is provided with two branches, namely a third branch and a fourth branch; the inlet end of the second high-pressure flushing pipe and the inlet end of the first high-pressure flushing pipe extend out of the packing tower, the fourth branch is communicated with the inlet end of the second high-pressure flushing pipe, and the third branch is communicated with the inlet end of the first high-pressure flushing pipe;

The third branch is provided with an eighth valve, and the fourth branch is provided with a ninth valve.

9. The composite flue gas purification system with a self-cleaning function according to claim 1, wherein the first pipeline switching structure comprises a first communicating pipe, a second communicating pipe, a fourth pressure gauge arranged on the second branch and close to the acid liquor flange inlet A, and a fifth pressure gauge arranged on the circulating water outlet pipe and at the circulating water flange outlet B;

The inlet end of the first communicating pipe and the inlet end of the second communicating pipe are both communicated with the second branch, and the outlet end of the first communicating pipe and the outlet end of the second communicating pipe are both communicated with the circulating water outlet pipe;

The connection part of the inlet end of the second communicating pipe and the second branch is close to the fourth pressure gauge, the connection part of the inlet end of the first communicating pipe and the second branch is far away from the fourth pressure gauge, and a tenth valve is arranged on a pipeline between the connection part of the inlet end of the first communicating pipe and the second branch and the connection part of the inlet end of the second communicating pipe and the second branch;

The connection part of the outlet end of the first communicating pipe and the circulating water outlet pipe is close to the fifth pressure gauge, the connection part of the outlet end of the second communicating pipe and the circulating water outlet pipe is far away from the fifth pressure gauge, and an eleventh valve is arranged on a pipeline between the connection part of the outlet end of the first communicating pipe and the circulating water outlet pipe and the connection part of the outlet end of the second communicating pipe and the circulating water outlet pipe;

the first communicating pipe is provided with a twelfth valve, and the second communicating pipe is provided with a thirteenth valve.

10. The composite flue gas purification system with the self-cleaning function according to claim 1, wherein the second pipeline switching structure comprises a third communicating pipe, a fourth communicating pipe, a sixth pressure gauge arranged on the circulating water inlet pipe and close to the inlet C of the circulating water flange, and a seventh pressure gauge arranged on the acid liquor discharge pipe and close to the outlet D of the acid liquor flange;

The inlet end of the third communicating pipe and the inlet end of the fourth communicating pipe are both communicated with the circulating water inlet pipe, and the outlet end of the third communicating pipe and the outlet end of the fourth communicating pipe are both communicated with the acid liquor discharge pipe;

The connection part of the inlet end of the third communicating pipe and the circulating water inlet pipe is close to the sixth pressure gauge, the connection part of the inlet end of the fourth communicating pipe and the circulating water inlet pipe is far away from the sixth pressure gauge, and a fourteenth valve is arranged on a pipeline between the connection part of the inlet end of the third communicating pipe and the circulating water inlet pipe and the connection part of the inlet end of the fourth communicating pipe and the circulating water inlet pipe;

The connection part of the outlet end of the fourth communicating pipe and the acid liquor discharge pipe is close to the seventh pressure gauge, the connection part of the outlet end of the third communicating pipe and the acid liquor discharge pipe is far away from the seventh pressure gauge, and a fifteenth valve is arranged on a pipeline between the connection part of the outlet end of the third communicating pipe and the acid liquor discharge pipe and the connection part of the outlet end of the fourth communicating pipe and the acid liquor discharge pipe;

the sixteenth valve is arranged on the third communicating pipe, and the seventeenth valve is arranged on the fourth communicating pipe.