Solid waste incineration flue gas purification system and method

Abstract

The invention belongs to the field of solid waste incineration flue gas purification, and discloses a solid waste incineration flue gas purification system and method.The system is provided with a flue gas cooling tower, and the flue gas cooling tower is connected with a first adsorption tower through a first branch of a first pipeline and connected with a second adsorption tower through a second branch; valves are arranged on the first branch and the second branch to alternately control flue gas entering, the induced draft fan is connected with the first adsorption tower through a third branch of the second pipeline and connected with the second adsorption tower through a fourth branch, and the heating fan is connected with the first adsorption tower through a fifth branch of the third pipeline and connected with the second adsorption tower through a sixth branch; according to the method, flue gas is guided into a flue gas cooling tower and then enters a first adsorption tower and a second adsorption tower to be alternately adsorbed and purified, and tail gas obtained after adsorption and purification is collected and discharged. The device can realize integrated removal of various pollutants, and has the advantages of high pollutant removal efficiency, complete removal types, energy conservation, environmental protection, low consumption, low secondary pollution, low investment, small occupied area and the like.

Description

Technical Field

[0001] This application belongs to the technical field of solid waste incineration flue gas purification, and particularly relates to a solid waste incineration flue gas purification system and method. Background Art

[0002] Currently, the incineration of solid waste generates a large amount of high-temperature flue gas from solid waste incineration. To avoid secondary pollution to the environment, these solid waste incineration flue gases need to be strictly purified to fully remove the pollutants therein before being discharged. The pollutants in solid waste incineration flue gases mainly include soot, sulfur dioxide, nitrogen oxides, acidic gases such as hydrogen chloride and hydrogen fluoride, carbon monoxide, dioxins, and heavy metals. The treatment and control of pollutants in high-temperature solid waste incineration flue gases are crucial for human health and environmental protection. Moreover, these flue gases often also carry waste heat with relatively high heat. If directly discharged, on the one hand, it will cause a large amount of energy loss, and on the other hand, it will cause serious pollution to the surrounding environment. Therefore, high-temperature solid waste incineration flue gases need to be purified before being discharged.

[0003] In the existing technology, traditional flue gas purification treatment systems usually have functions such as cooling, dust removal, acid removal, and denitrification of high-temperature solid waste incineration gases. Traditional flue gas purification treatment processes mainly include SNCR denitrification (selective non-catalytic reduction denitrification), acid removal, activated carbon injection for dioxin removal, bag dust removal, waste heat recovery, etc. Although this process can meet the needs to a certain extent, it has the following deficiencies:

[0004] First, the flue gas is directly denitrified at high temperature and then desulfurized, resulting in low denitrification efficiency;

[0005] Second, the process flow is long, resulting in an increase in system complexity, investment, and floor area;

[0006] Third, process conditions (such as temperature, flue gas residence time, etc.) cannot be accurately controlled, resulting in the pollutant removal effect being difficult to achieve the expected value;

[0007] Fourth, it consumes a large amount of reducing agents (ammonia or urea), limestone, etc., and there are problems such as ammonia escape and secondary pollution discharge of desulfurization wastewater. Summary of the Invention

[0008] The purpose of this application is to overcome the defects of the existing technology and provide a solid waste incineration flue gas purification system and method.

[0009] To achieve the above purpose, this application provides the following technical solutions:

[0010] In a first aspect, the present application provides a solid waste incineration flue gas purification system, including a flue gas cooling tower. The flue gas cooling tower is connected to a first adsorption tower through a first branch of a first pipeline and to a second adsorption tower through a second branch. Valves are provided on the first branch and the second branch to alternately control the entry of flue gas. An induced draft fan is connected to the first adsorption tower through a third branch of a second pipeline and to the second adsorption tower through a fourth branch. A heating fan is connected to the first adsorption tower through a fifth branch of a third pipeline and to the second adsorption tower through a sixth branch.

[0011] In some embodiments, valves are provided on each of the third branch, the fourth branch, the fifth branch, and the sixth branch.

[0012] In some embodiments, a solid waste incinerator is connected to the first adsorption tower through a seventh branch of a fourth pipeline and to the second adsorption tower through an eighth branch.

[0013] In some embodiments, valves are provided on the seventh branch and the eighth branch.

[0014] In some embodiments, one end of a fifth pipeline is connected to the heating fan, and the other end is an air inlet.

[0015] In some embodiments, a sixth pipeline connects the fourth pipeline and the fifth pipeline.

[0016] In some embodiments, the flue gas cooling tower includes a bottom layer, a middle layer, and a top layer, and the flue gas flows from bottom to top. Circulating cooling water flowing in a direction opposite to the flue gas is arranged in the bottom layer. Atomized cold water is arranged in the middle layer to exchange heat with the flue gas. Circulating water and packing are provided in the top layer.

[0017] In a second aspect, the present application provides a method for purifying solid waste incineration flue gas, including:

[0018] The flue gas enters the flue gas cooling tower, and the flue gas is cooled by circulating cooling water in the bottom layer.

[0019] The flue gas enters the middle layer from the bottom layer, and the flue gas is further cooled through the middle layer to avoid the temperature range for dioxin formation.

[0020] The flue gas enters the top layer from the middle layer, and circulating water is used for cooling.

[0021] The flue gas exiting from the top layer enters the first adsorption tower and the second adsorption tower through the first pipeline for alternate adsorption purification, and the tail gas after adsorption purification is collected and discharged through the induced draft fan.

[0022] In some embodiments, the adsorption and regeneration cooling processes are alternately carried out in the first adsorption tower and the second adsorption tower. The adsorbent is alternately heated and regenerated by high-temperature air heated by a heating fan, and after the regeneration is completed, it is blown with cold air.

[0023] In some embodiments, when the first adsorption tower is saturated with adsorption, the valves on the first branch and the third branch are closed and the valves on the second branch and the fourth branch are opened, and the flue gas is switched to the second adsorption tower for adsorption purification. At this time, the first adsorption tower is heated and regenerated, and after being completely regenerated and cooled, it waits for the next switching and use;

[0024] When the second adsorption tower is saturated with adsorption, the valves on the first branch and the third branch are opened and the valves on the second branch and the fourth branch are closed, and the flue gas is switched to the first adsorption tower for adsorption purification. At this time, the second adsorption tower is heated and regenerated, and after being completely regenerated and cooled, it waits for the next switching and use;

[0025] The pollutant gas regenerated is sent back to the furnace for reduction treatment through the outlet of the regeneration gas circuit of the fourth pipeline.

[0026] Compared with the prior art, the solid waste incineration flue gas purification system and method provided by the present application have the following

[0027] Beneficial effects:

[0028] The flue gas cooling tower and the solid waste incineration flue gas purification system provided by the present application can achieve the integrated removal of various pollutants, and have the advantages of high pollutant removal efficiency, complete removal types, energy conservation and environmental protection, less consumption, less secondary pollution, less investment and small floor area. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] In order to more clearly illustrate the technical solutions of the present application, the drawings required for the technical description will be briefly introduced below.

[0030] Figure 1 It is a schematic diagram of the solid waste incineration flue gas purification system provided by the present application.

[0031] Description of the reference numerals:

[0032] 1. Flue gas cooling tower; 2. First adsorption tower; 3. Second adsorption tower; 4. Induced draft fan; 5. Heating fan;

[0033] 11. First pipeline; 12. Second pipeline; 13. Third pipeline; 14. Fourth pipeline; 15. Fifth pipeline; 16. Sixth pipeline;

[0034] 21. Flue gas inlet; 22. Circulating cooling water inlet; 23. Circulating cooling water outlet; 24. Spray cooling water inlet; 25. Air inlet; 26. Regenerated gas return furnace outlet. Detailed implementation manners

[0035] The following is a further detailed description through specific implementation manners.

[0036] As Figure 1 shown, the embodiment of the present application provides a solid waste incineration flue gas purification system, including a flue gas cooling tower 1, a first adsorption tower 2, a second adsorption tower 3, a draft fan 4, a heating fan 5 and a plurality of connecting pipelines. The flue gas cooling tower 1 is connected to the first adsorption tower 2 and the second adsorption tower 3 through a first pipeline 11. The draft fan 4 is connected to the first adsorption tower 2 and the second adsorption tower 3 through a second pipeline 12. The heating fan 5 is connected to the first adsorption tower 2 and the second adsorption tower 3 through a third pipeline 13. The first adsorption tower 2 and the second adsorption tower 3 are connected to the solid waste incinerator and a sixth pipeline 16 through a fourth pipeline 14. One end of a fifth pipeline 15 is connected to the heating fan 5, and the other end is an air inlet 25. One end of the sixth pipeline 16 is connected to the fourth pipeline 14, and the other end is connected to the fifth pipeline 15.

[0037] Specifically, the first pipeline 11 has a first branch and a second branch. The first branch is connected to the first adsorption tower 2, and the second branch is connected to the second adsorption tower 3. The second pipeline 12 has a third branch and a fourth branch. The third branch is connected to the first adsorption tower 2, and the fourth branch is connected to the second adsorption tower 3. The third pipeline 13 has a fifth branch and a sixth branch. The fifth branch is connected to the first adsorption tower 2, and the sixth branch is connected to the second adsorption tower 3. The fourth pipeline 14 has a seventh branch and an eighth branch. The seventh branch is connected to the first adsorption tower 2, and the eighth branch is connected to the second adsorption tower 3.

[0038] Valves are provided on the first branch, the second branch, the third branch, the fourth branch, the fifth branch, the sixth branch, the seventh branch and the eighth branch.

[0039] Optionally, the valve can be a butterfly valve or a gate valve.

[0040] In this embodiment, adsorption purification is carried out alternately. The low-temperature flue gas enters the first pipeline 11 from the top layer of the flue gas cooling tower 1, and the low-temperature flue gas flows into the adsorption tower inlet. The downstream of the first pipeline 11 is divided into a first branch and a second branch. The valves on the first branch and the third branch are opened, and the valves on the second branch and the fourth branch are closed, so that the low-temperature flue gas enters the first adsorption tower 2 through the first branch for adsorption purification; when the first adsorption tower 2 is saturated with adsorption, the valves on the first branch and the third branch are closed, and the valves on the second branch and the fourth branch are opened, so that the low-temperature flue gas enters the second adsorption tower 3 through the second branch for adsorption purification, realizing the switching of the low-temperature flue gas to the second adsorption tower 3 for alternate adsorption purification. At this time, the first adsorption tower 2 is heated and regenerated, and after complete regeneration and cooling, it waits for the next switching use. The pollutant gas regenerated is subjected to furnace return reduction treatment from the outlet 26 of the regeneration gas circuit of the fourth pipeline 14. The high-temperature air heats and regenerates the adsorption tower. The fifth pipeline 15, the third pipeline 13, the adsorption tower, the fourth pipeline 14, and the sixth pipeline 16 are circulating high-temperature air pipelines, in which the regenerated pollutant gas will be mixed. During the regeneration process, the valve before the outlet 26 of the regeneration gas return to the furnace is opened. Part of these high-temperature mixed gases circulates in the pipeline, and the other part enters the solid waste incinerator for circuit reduction treatment. When the regeneration is completed, the valve on the sixth pipeline 16 is closed, and cold blowing is carried out through cold air. The cold air enters the solid waste incinerator through the fifth pipeline 15, the third pipeline 13, the adsorption tower, the fourth pipeline 14, and the outlet 26 of the regeneration gas return to the furnace.

[0041] Among them, the adsorbents in the first adsorption tower 2 and the second adsorption tower 3 are alternately heated and regenerated by the high-temperature air heated by the heating fan 5. The high-temperature air flows into the adsorption tower inlet, and after the regeneration is completed, cold blowing is carried out with cold air. When the second adsorption tower 3 is performing adsorption purification and the adsorbent in the first adsorption tower 2 needs to be heated and regenerated, the valves on the sixth branch of the third pipeline 13 and the eighth branch of the fourth pipeline 14 need to be closed, and the valves on the fifth branch and the seventh branch are opened to allow the high-temperature air heated by the hot air blower 5 to enter the first adsorption tower 2; when the adsorbent in the second adsorption tower 3 needs to be heated and regenerated, the valves on the fifth branch and the seventh branch are closed, and the valves on the sixth branch and the eighth branch are opened.

[0042] Finally, the tail gas after adsorption purification is collected and discharged by the induced draft fan 4. The tail gas enters the induced draft fan 4 from the second pipeline 12 and is discharged. The valves provided on the third branch and the fourth branch of the second pipeline 12 are used to respectively control the tail gas discharge of the corresponding first adsorption tower 2 and the second adsorption tower 3.

[0043] In one embodiment, a butterfly valve is provided between the fourth pipeline 14 and the solid waste incinerator. The outlet 26 of the regeneration gas circuit of the fourth pipeline 14 is connected to the solid waste incinerator.

[0044] In one embodiment, the fifth pipeline 15 is connected to the fourth pipeline 14 through the sixth pipeline 16. High-temperature air is used to heat and regenerate the adsorption tower. The fifth pipeline 15, the third pipeline 13, the adsorption tower, the fourth pipeline 14, and the sixth pipeline 16 form a circulating high-temperature air pipeline, in which the pollutant gas regenerated will be mixed. During the regeneration process, the valve before the outlet 26 is opened. For these high-temperature mixed gases, a part of them circulates in the pipeline, and the other part enters the solid waste incinerator for loop reduction treatment. When the regeneration is completed, the valve on the sixth pipeline 16 is closed, and cold blowing is carried out with cold air. The cold air enters the solid waste incinerator through the fifth pipeline 15, the third pipeline 13, the adsorption tower, the fourth pipeline 14, and the regenerated gas circuit outlet 26. When heating and regenerating, a circulating pipeline is formed, which can make the heat energy reused, reduce the power loss, and stabilize the temperature field.

[0045] As Figure 1 shown, the flue gas cooling tower 1 is divided into three layers and adopts three-stage cooling. The first layer (the bottom layer) is the first-stage cooling layer, the second layer (the middle layer) is the second-stage rapid cooling layer, and the third layer (the top layer) is the third-stage deep cooling layer.

[0046] The bottom layer of the flue gas cooling tower uses circulating cooling water to cool the high-temperature flue gas. The heat exchanger is a water-cooled shell-and-tube heat exchange device. The flue gas passes through the tube side, and the cooling water passes through the shell side. The high-temperature flue gas and the low-temperature cooling water exchange heat reversely, and the flue gas drops from about 900 degrees to about 500 degrees. The middle layer of the flue gas cooling tower rapidly cools the high-temperature flue gas to avoid the temperature zone for dioxin formation. With the help of compressed air, the cold water is atomized by the nozzle and evenly sprinkled into the middle layer of the flue gas cooling tower, fully contacting with the high-temperature flue gas and rapidly exchanging heat. The cold water evaporates into a gaseous state and enters the next purification unit together with the flue gas. This heat exchange process does not exceed 1 s. The temperature of the flue gas after passing through the rapid cooling tower is about below 200 degrees. The top layer of the flue gas cooling tower uses the circulating water cooled by the refrigerator to cool the flue gas. A demister is arranged at the top of the flue gas cooling tower, and the flue gas outlet is cooled to 5°C. Packing is arranged in the top layer of the flue gas cooling tower, and liquid collection pools are arranged at the bottoms of the three layers of the flue gas cooling tower.

[0047] The usage process of the system provided by this application is as follows:

[0048] The flue gas from the solid waste incineration enters the flue gas cooling tower 1 through the flue from the flue gas inlet 21. The flue gas cooling tower 1 is divided into three layers, and the flue gas flows from bottom to top. The flue is outside the cooling tower and connects the solid waste incinerator and the flue gas cooling tower.

[0049] The bottom layer of the flue gas cooling tower 1 uses circulating cooling water to cool high-temperature flue gas. The circulating cooling water enters the bottom layer of the flue gas cooling tower 1 from the circulating cooling water inlet 22 and flows out of the bottom layer from the circulating cooling water outlet 23. The heat exchanger is a water-cooled tubular heat exchange device. The flue gas passes through the tube side, and the cooling water passes through the shell side. The high-temperature flue gas and the low-temperature cooling water exchange heat in a countercurrent manner, and the temperature of the flue gas drops from about 900 degrees to about 500 degrees.

[0050] The middle layer of the flue gas cooling tower 1 rapidly cools the high-temperature flue gas to avoid the temperature range for dioxin formation. With the help of compressed air, the cold water is atomized by the nozzle and evenly sprayed into the middle layer of the flue gas cooling tower 1, making full contact with the high-temperature flue gas and rapidly exchanging heat. The cold water evaporates into a gaseous state, and this heat exchange process takes no more than 1 s. The temperature of the flue gas after passing through the quench tower heat exchanger is approximately below 200 degrees.

[0051] The top layer of the flue gas cooling tower 1 uses circulating water cooled by a refrigeration machine to cool the flue gas. The circulating water enters from the spray cooling water inlet 24, and the spray cooling water inlet 24 is arranged outside the tower. A demister is arranged at the top of the flue gas cooling tower 1, and the flue gas outlet is cooled to 5 °C. Packing is arranged inside the top layer, and liquid collection pools are arranged at the bottoms of the three layers of the flue gas cooling tower 1. The low-temperature flue gas enters the first adsorption tower 2 for adsorption and purification. The first adsorption tower 2 and the second adsorption tower 3 are filled with adsorbents, and the adsorbent is a zeolite molecular sieve. When the first adsorption tower 2 is saturated with adsorption, the flue gas is switched to the second adsorption tower 3 for alternate adsorption and purification through a switching valve (such as a butterfly valve or a gate valve). At this time, the first adsorption tower 2 is heated for regeneration. After complete regeneration and cooling, it waits for the next switching for use. The pollutant gas regenerated is sent back to the furnace for reduction treatment. The adsorbents in the first adsorption tower 2 and the second adsorption tower 3 are alternately heated and regenerated by hot air heated by a heating fan 5, and cold air is used for cold blowing after the regeneration ends. The finally adsorbed and purified tail gas is collected and discharged by an induced draft fan 4, that is, the outlet flue gas is collected to the inlet of the induced draft fan.

[0052] In addition, based on the above system, the embodiment of the present application further provides a method for purifying flue gas from solid waste incineration, including:

[0053] The flue gas from solid waste incineration enters the flue gas cooling tower 1 through the flue. In the bottom layer of the flue gas cooling tower 1, circulating cooling water is used to cool the high-temperature flue gas; in the middle layer of the flue gas cooling tower 1, the high-temperature flue gas is rapidly cooled to avoid the temperature range for dioxin formation, and the temperature of the flue gas after passing through the heat exchange in the middle layer of the flue gas cooling tower 1 is approximately below 200 degrees; in the top layer of the flue gas cooling tower 1, the circulating water cooled by a refrigeration machine is used for cooling, and the flue gas outlet is cooled to 5 °C;

[0054] The low-temperature flue gas from the top layer outlet of the flue gas cooling tower 1 enters the adsorption tower (the first adsorption tower 2 and the second adsorption tower 3) for adsorption and purification, and the finally adsorbed and purified tail gas is collected and discharged by an induced draft fan 4.

[0055] The adsorption and regeneration cooling processes are alternately carried out in the first adsorption tower 2 and the second adsorption tower 3. The adsorbent is alternately heated and regenerated by the hot air heated by the heating fan 5, and cold air is used for cold blowing after the regeneration is completed.

[0056] When the first adsorption tower 2 is saturated with adsorption, the low-temperature flue gas is switched to the second adsorption tower 3 for adsorption purification through the switching valve (closing the valves on the first branch and the third branch and opening the valves on the second branch and the fourth branch). At this time, the first adsorption tower 2 is heated and regenerated. After being completely regenerated and cooled, it waits for the next switching for use; when the second adsorption tower 3 is saturated with adsorption, the low-temperature flue gas is switched to the first adsorption tower 2 for adsorption purification through the switching valve (opening the valves on the first branch and the third branch and closing the valves on the second branch and the fourth branch). At this time, the second adsorption tower 3 is heated and regenerated. After being completely regenerated and cooled, it waits for the next switching for use. The pollutant gas regenerated is subjected to furnace return reduction treatment through the outlet 26 of the regeneration gas circuit of the fourth pipeline 14.

[0057] The above is only the specific implementation manner of the present application, but the protection scope of the present application is not limited thereto. Any changes or substitutions that can be easily thought of by those skilled in the technical field of the present application within the technical scope disclosed by the present application should be covered by the protection scope of the present application.

Claims

1. A solid waste incineration flue gas purification system, characterized in that, It includes a flue gas cooling tower (1), which is connected to a first adsorption tower (2) through a first branch of a first pipeline (11) and to a second adsorption tower (3) through a second branch. Valves are provided on the first branch and the second branch to alternately control the entry of flue gas. A draft fan (4) is connected to the first adsorption tower (2) through a third branch of a second pipeline (12) and to the second adsorption tower (3) through a fourth branch. A heating fan (5) is connected to the first adsorption tower (2) through a fifth branch of a third pipeline (13) and to the second adsorption tower (3) through a sixth branch.

2. The solid waste incineration flue gas purification system according to claim 1, wherein Valves are provided on the third branch, the fourth branch, the fifth branch and the sixth branch.

3. The solid waste incineration flue gas purification system according to claim 1, characterized in that, The solid waste incinerator is connected to the first adsorption tower (2) through a seventh branch of a fourth pipeline (14) and to the second adsorption tower (3) through an eighth branch.

4. The solid waste incineration flue gas purification system according to claim 3, wherein Valves are provided on the seventh branch and the eighth branch.

5. The solid waste incineration flue gas purification system according to claim 3, characterized in that, One end of a fifth pipeline (15) is connected to the heating fan (5), and the other end is an air inlet (25).

6. The solid waste incineration flue gas purification system according to claim 5, characterized in that, A sixth pipeline (16) connects the fourth pipeline (14) and the fifth pipeline (15).

7. The solid waste incineration flue gas purification system according to claim 1, wherein, The flue gas cooling tower (1) includes a bottom layer, a middle layer and a top layer, and the flue gas flows from bottom to top. Circulating cooling water flowing in the opposite direction to the flue gas is arranged in the bottom layer. Atomized cold water is arranged in the middle layer to exchange heat with the flue gas. Circulating water and packing are provided in the top layer.

8. A method for purifying flue gas from solid waste incineration, characterized in that, It includes: The flue gas enters the flue gas cooling tower (1), and the flue gas is cooled by the circulating cooling water in the bottom layer. The flue gas enters the middle layer from the bottom layer, and the flue gas is further cooled by the middle layer to avoid the temperature zone for dioxin formation. The flue gas enters the top layer from the middle layer, and circulating water is used for cooling. The flue gas exiting from the top layer enters the first adsorption tower (2) and the second adsorption tower (3) through the first pipeline (11) for alternate adsorption and purification, and the tail gas after adsorption and purification is collected and discharged through the draft fan (4).

9. The method for purifying waste incineration flue gas according to claim 8, characterized in that, Adsorption and regeneration cooling processes are alternately carried out in the first adsorption tower (2) and the second adsorption tower (3). The adsorbent is alternately heated and regenerated by high-temperature air heated by the heating fan (5), and cold air is used for cold blowing after the regeneration ends.

10. The method for purifying waste incineration flue gas according to claim 9, characterized in that, When the first adsorption tower (2) is saturated with adsorption, the valves on the first branch and the third branch are closed, and the valves on the second branch and the fourth branch are opened, and the flue gas is switched to the second adsorption tower (3) for adsorption and purification. At this time, the first adsorption tower (2) is heated and regenerated, and after complete regeneration and cooling, it waits for the next switch for use. When the second adsorption tower (3) is saturated with adsorption, the valves on the first branch and the third branch are opened, and the valves on the second branch and the fourth branch are closed, and the flue gas is switched to the first adsorption tower (2) for adsorption and purification. At this time, the second adsorption tower (3) is heated and regenerated, and after complete regeneration and cooling, it waits for the next switch for use. The pollutant gas regenerated is subjected to back-furnace reduction treatment through the outlet (26) of the regeneration gas circuit of the fourth pipeline (14).

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