Method and apparatus for cleaning a hybrid liquid ammonia vaporizer

Abstract

The application discloses a cleaning method and device of a mixed liquid ammonia evaporator, and belongs to the technical field of industrial emission. The liquid ammonia evaporator can be cleaned without replacing equipment through cooperation of air inlet of the inner pipe and water inlet of the outer pipe. The connection part of the coil inlet and the outer pipe is sealed, so that gas cannot enter the outer pipe when the inner pipe is in air inlet. When the outer pipe is in water inlet, a gap is formed between the sealing sheet and the outer pipe, and water enters the coil of the liquid ammonia evaporator through the gap, so that ammonia gas leakage and harm are avoided.

Description

Technical Field

[0001] This invention belongs to the field of industrial emission technology, and more specifically, relates to a cleaning method and apparatus for a mixed liquid ammonia evaporator. Background Technology

[0002] The main method for flue gas denitrification in thermal power plant boilers is the ammonia-based SCR (Selective Catalytic Reduction) process, which uses ammonia as a reducing agent. In the process, liquid ammonia is first evaporated into ammonia gas, which is then transported to the SCR zone, mixed with dilution air, and injected into the flue gas upstream of the SCR reactor through a distribution grid for denitrification. Because liquid ammonia generally contains impurities such as tar and iron compounds, solid residues remain after the liquid ammonia vaporizes in the ammonia evaporator coils. Over time, this residues eventually reduce the inner diameter of the coils or even completely block them, affecting the safe operation of the unit.

[0003] A search revealed a Chinese invention entitled "A Cleaning Device and Method for Liquid Ammonia Evaporator Coils" (application number: 201811537345.5, application date: 2018.12.15). This invention includes a nitrogen control device, a cleaning control device, and a demineralized water control device connected to the liquid ammonia evaporator coils. The cleaning method for the liquid ammonia evaporator coils comprises four steps: ammonia replacement, cleaning with a cleaning solution, and nitrogen purging. Using this cleaning device and method to clean the liquid ammonia evaporator coils thoroughly removes impurities from the coils, ensuring the normal operation of the liquid ammonia evaporator and further guaranteeing the safe operation of the unit. This cleaning device and method are simple, fast, safe, environmentally friendly, and low-cost, and are suitable for cleaning clogged liquid ammonia evaporator coils in the ammonia areas of all coal-fired power plants.

[0004] The shortcomings of the aforementioned application are that it requires frequent equipment replacement, which can easily lead to gas leaks and hazards, and therefore needs to be improved. Summary of the Invention

[0005] 1. The technical problem that the invention aims to solve

[0006] The purpose of this invention is to solve the shortcomings of existing cleaning devices, such as the need for frequent equipment replacement and the risk of gas leakage causing harm.

[0007] 2. Technical Solution

[0008] To achieve the above objectives, the technical solution provided by this invention is as follows:

[0009] The present invention discloses a cleaning method and apparatus for a hybrid liquid ammonia evaporator, comprising a liquid ammonia evaporator, a U-shaped plate, a coil inlet, an outer pipe, an inner pipe, a water tank, a discharge pipe, a collection box, a gas box, and an ammonia water tank.

[0010] Preferably, one end of the outer pipe is fixedly connected to the coil inlet, the coil inlet is fixedly connected to the liquid ammonia evaporator, spring bottom plates are arranged in an array on the inner wall of the coil inlet, springs are fixedly connected to the outer walls of the spring bottom plates, a sealing sheet is arranged in the inner cavity of the coil inlet, the sealing sheet is closely attached to the end plane of the outer pipe by the thrust of the springs, the sealing sheet is used for preventing gas from entering the inner cavity of the outer pipe, and one end of the outer pipe is flush with one end of the inner pipe.

[0011] Preferably, the centers of the horizontal ends of the coil inlet, the sealing sheet, the outer pipe and the inner pipe are all on the same axis, the radii of the sealing sheet, the outer pipe and the inner pipe are R1, R2 and R3 respectively, R3 < R1 < R2, a through hole is arranged at the center of the sealing sheet, the radius of the through hole is r1, the inner cavity radii of the outer pipe and the inner pipe are r2 and r3 respectively, r3 < r1 < R3, r2 < R1.

[0012] Preferably, the outer pipe passes through the outer wall of the U-shaped plate and is fixedly connected to the water tank, the inner pipe passes through the water tank and the U-shaped plate, the water tank is provided with a pump for accelerating the liquid flow rate, a third pipeline and a fourth pipeline are fixedly connected to the outer wall of the inner pipe, the third pipeline is used for circulating nitrogen, and the fourth pipeline is used for circulating ammonia gas.

[0013] Preferably, the gas box is fixedly installed on the outer wall of the U-shaped plate, the gas box comprises a partition plate, the partition plate divides the inner cavity of the gas box into two parts which are a nitrogen chamber and an ammonia gas chamber respectively, the bottom of the third pipeline communicates with the nitrogen chamber, the bottom of the fourth pipeline communicates with the ammonia gas chamber, and both the third pipeline and the fourth pipeline are provided with gas valves for accelerating gas circulation.

[0014] Preferably, the bottom of the gas box is fixedly connected with a first pipeline and a second pipeline, the first pipeline communicates with the nitrogen chamber, the second pipeline communicates with the ammonia gas chamber, one end of the first pipeline is fixedly connected with the top of the collection box, and one end of the second pipeline is fixedly connected with the top of the ammonia water tank.

[0015] Preferably, one end of the discharge pipe is fixedly connected to the coil outlet of the liquid ammonia evaporator, the other end of the discharge pipe passes through the top of the collection box and enters the interior of the collection box, the collection box communicates with the ammonia water tank through a pipeline, and the pipeline is provided with a water valve for opening or closing the pipeline.

[0016] Preferably, the ammonia water tank comprises a filter plate, a circulation pipe and a heating block, both the filter plate and the heating block are located in the inner cavity of the ammonia water tank, the filter plate is used for filtering impurities in ammonia water, the heating block is used for heating ammonia water to generate ammonia gas, the water inlet of the ammonia water tank is higher than the position of the filter plate, the water outlet of the ammonia water tank is lower than the position of the filter plate, the water outlet of the ammonia water tank communicates with the circulation pipe, one end of the circulation pipe communicates with the water tank, and the circulation pipe is used for circulating liquid in the ammonia water tank and the water tank.

[0017] A cleaning method for a hybrid liquid ammonia evaporator, the steps of which are as follows:

[0018] S100: Fill the collection tank with water, open the gas valve of the third pipe to inject nitrogen into the liquid ammonia evaporator, replace the ammonia in the liquid ammonia evaporator, the water in the collection tank absorbs the ammonia, and the nitrogen enters the nitrogen chamber from the first pipe.

[0019] S200, close the gas valve of the third pipeline, fill the water tank with water, turn on the pump, and water enters the coil of the liquid ammonia evaporator to flush the inside of the coil.

[0020] S300, open the water valve on the pipe connecting the collection tank and the ammonia tank to allow the liquid in the collection tank to flow into the ammonia tank.

[0021] S400, turn on the heating block to heat the liquid in the ammonia tank. The liquid in the ammonia tank is filtered and heated to generate ammonia gas. The ammonia gas enters the ammonia chamber through the second pipe, and then the liquid enters the water tank again through the circulation pipe. Repeat the above operation multiple times.

[0022] S500, cleaning complete. Turn off the pump in the water tank, open the gas valve on the fourth pipe, and inject ammonia gas into the coil of the liquid ammonia evaporator.

[0023] The specific process of S200 is as follows: start the pump to increase water pressure. When water enters the coil inlet from the inner cavity of the outer tube, it will exert pressure on the sealing plate. The spring will contract, and a gap will be created between the sealing plate and the outer tube. Water will flow into the coil of the liquid ammonia evaporator from the gap.

[0024] 3. Beneficial effects

[0025] Compared with the prior art, the technical solution provided by this invention has the following advantages:

[0026] (1) The present invention provides a cleaning method and apparatus for a mixed liquid ammonia evaporator, which belongs to the field of industrial emission technology. By combining the air inlet of the inner pipe and the water inlet of the outer pipe, the liquid ammonia evaporator can be cleaned without replacing the equipment. By sealing the connection between the coil inlet and the outer pipe, the gas will not enter the outer pipe when the inner pipe is inlet. When the outer pipe is inlet, the sealing plate and the outer pipe will form a gap, and the water will enter the coil of the liquid ammonia evaporator from the gap, thus avoiding the leakage of ammonia gas and causing harm. Attached Figure Description

[0027] Figure 1 This is an overall structural diagram of a cleaning method and apparatus for a hybrid liquid ammonia evaporator according to the present invention;

[0028] Figure 2 This is another overall structural diagram of a cleaning method and apparatus for a hybrid liquid ammonia evaporator according to the present invention;

[0029] Figure 3 This is a diagram of the internal structure at point A of a cleaning method and apparatus for a hybrid liquid ammonia evaporator according to the present invention.

[0030] Figure 4 This is a structural diagram at point B of a cleaning method and apparatus for a hybrid liquid ammonia evaporator according to the present invention;

[0031] Figure 5 This is a cross-sectional view at point B of a cleaning method and apparatus for a hybrid liquid ammonia evaporator according to the present invention;

[0032] Figure 6 This is a diagram of the internal structure at point C of a cleaning method and apparatus for a hybrid liquid ammonia evaporator according to the present invention.

[0033] Explanation of the labels in the diagram:

[0034] 1. Liquid ammonia evaporator; 2. U-shaped plate; 3. Coil inlet; 4. Outer pipe; 5. Inner pipe; 6. Water tank; 7. Discharge pipe; 8. Circulation pipe; 9. Collection box; 10. First pipeline; 11. Second pipeline; 12. Gas tank; 13. Nitrogen chamber; 14. Ammonia chamber; 15. Baffle plate; 16. Third pipeline; 17. Fourth pipeline; 18. Ammonia water tank; 19. Filter plate; 20. Heating block; 21. Sealing plate; 22. Spring; 23. Spring base plate. Detailed Implementation

[0035] To facilitate understanding of the present invention, a more complete description of the invention will be given below with reference to the accompanying drawings, which illustrate several embodiments of the invention. However, the invention can be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided so that the disclosure of the invention will be more thorough and complete.

[0036] It should be noted that when an element is referred to as being "fixed to" another element, it can be directly on the other element or there may be an intervening element; when an element is referred to as being "connected to" another element, it can be directly connected to the other element or there may be an intervening element; the terms "vertical," "horizontal," "left," "right," and similar expressions used in this document are for illustrative purposes only.

[0037] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains; the terminology used herein in the specification of this invention is for the purpose of describing particular embodiments only and is not intended to limit the invention; the term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0038] Example 1

[0039] See attached document Figures 1-6As shown, a cleaning method and device for a hybrid liquid ammonia evaporator in this embodiment includes a liquid ammonia evaporator 1, a U-shaped plate 2, a coil inlet 3, an outer tube 4, an inner tube 5, a water tank 6, a discharge pipe 7, a collection tank 9, a gas tank 12 and an ammonia water tank 18.

[0040] In this embodiment, one end of the outer tube 4 is fixedly connected to the coil inlet 3, and the coil inlet 3 is fixedly connected to the liquid ammonia evaporator 1. Spring base plates 23 are arranged in an array on the inner wall of the coil inlet 3, a spring 22 is fixedly connected to the outer wall of each spring base plate 23, and a sealing sheet 21 is arranged in the inner cavity of the coil inlet 3. The sealing sheet 21 is closely attached to the end plane of the outer tube 4 by the thrust of the spring 22, and the sealing sheet 21 is configured to prevent gas from entering the inner cavity of the outer tube 4. One end of the outer tube 4 is flush with one end of the inner tube 5. With this designed structure, when the sealing sheet 21 is subjected to the pressure of water pumped out, it will move away from the outer tube 4 due to the contraction of the spring 22, thereby allowing water to flow through the gap. When the pump is turned off, the spring 22 will recover, so that the sealing sheet 21 is closely attached to the outer tube 4 again, which can prevent gas leakage.

[0041] In this embodiment, the centers of the horizontal ends of the coil inlet 3, the sealing sheet 21, the outer tube 4 and the inner tube 5 are all on the same axis. The radii of the sealing sheet 21, the outer tube 4 and the inner tube 5 are R1, R2 and R3 respectively, and R3<R1<R2. A through hole is provided at the center of the sealing sheet 21, the radius of the through hole is r1, the inner cavity radii of the outer tube 4 and the inner tube 5 are r2 and r3 respectively, and r3<r1<R3, r2<R1. With this structural design, R3<R1<R2, r3<r1<R3, r2<R1. Since the inner tube 5 is located in the inner cavity of the outer tube 4, the radius of the inner tube 5 is smaller than that of the outer tube 4. When the radius of the through hole of the sealing sheet 21 is smaller than the radius of the inner cavity of the inner tube 5, gas flow will be impeded. When the radius of the through hole of the sealing sheet 21 is larger than the radius of the inner tube 5, gas and liquid will leak. When the radius of the sealing sheet 21 is smaller than the radius of the inner cavity of the outer tube 4, gas and liquid will leak. When the radius of the sealing sheet 21 is larger than the radius of the inner cavity of the outer tube 4 and smaller than the radius of the outer tube 4, the sealing effect is the best and the safety is higher.

[0042] In this embodiment, the outer tube 4 passes through the outer wall of the U-shaped plate 2 and is fixedly connected to the water tank 6, the inner tube 5 penetrates the water tank 6 and passes through the U-shaped plate 2, and the water tank 6 is provided with a pump for accelerating the flow speed of liquid. A third pipe 16 and a fourth pipe 17 are fixedly connected to the outer wall of the inner tube 5, the third pipe 16 is for nitrogen circulation, and the fourth pipe 17 is for ammonia circulation. With this designed structure, the third pipe 16 and the fourth pipe 17 are designed separately, which can fill nitrogen or ammonia into the coil of the liquid ammonia evaporator 1 as required, facilitating control.

[0043] In this embodiment, the gas chamber 12 is fixedly installed on the outer wall of the U-shaped plate 2. The gas chamber 12 includes a partition 15, which divides the inner cavity of the gas chamber 12 into two parts, namely a nitrogen chamber 13 and an ammonia chamber 14. The bottom of the third pipe 16 is connected to the nitrogen chamber 13, and the bottom of the fourth pipe 17 is connected to the ammonia chamber 14. Both the third pipe 16 and the fourth pipe 17 are equipped with gas valves to accelerate gas flow. In this design, the nitrogen chamber 13 and the ammonia chamber 14 are used to store nitrogen and ammonia respectively, preventing ammonia from mixing with nitrogen and affecting the cleaning effect.

[0044] In this embodiment, the bottom of the gas tank 12 is fixedly connected to a first pipe 10 and a second pipe 11. The first pipe 10 is connected to the nitrogen chamber 13, and the second pipe 11 is connected to the ammonia chamber 14. One end of the first pipe 10 is fixedly connected to the top of the collection box 9, and one end of the second pipe 11 is fixedly connected to the top of the ammonia tank 18. With this design, ammonia and nitrogen can be collected simultaneously when replacing ammonia. The ammonia and nitrogen enter the ammonia chamber 14 and the nitrogen chamber 13 respectively, which can be recycled and save costs.

[0045] In this embodiment, one end of the discharge pipe 7 is fixedly connected to the coil outlet of the liquid ammonia evaporator 1, and the other end of the discharge pipe 7 passes through the top of the collection box 9 and enters the interior of the collection box 9. The collection box 9 is connected to the ammonia water tank 18 through a pipe. The pipe is equipped with a water valve for opening or closing the pipe. With this design, when the collection box 9 is filled with water, the discharged ammonia gas will dissolve in the water, and the nitrogen gas will directly enter the nitrogen chamber 13. Because there is no direct discharge of ammonia gas, the impact on the environment is small.

[0046] In this embodiment, the ammonia tank 18 includes a filter plate 19, a circulation pipe 8, and a heating block 20. Both the filter plate 19 and the heating block 20 are located inside the ammonia tank 18. The filter plate 19 is used to filter impurities in the ammonia water, and the heating block 20 is used to heat the ammonia water to generate ammonia gas. The inlet of the ammonia tank 18 is higher than the position of the filter plate 19, and the outlet of the ammonia tank 18 is lower than the position of the filter plate 19. The outlet of the ammonia tank 18 is connected to the circulation pipe 8, and one end of the circulation pipe 8 is connected to the water tank 6. The circulation pipe 8 is used to circulate the liquid in the ammonia tank 18 and the water tank 6. With this design, heating the liquid in the ammonia tank 18 will generate ammonia gas, which will enter the ammonia gas chamber 14. The outlet is higher than the position of the filter plate 19, and the liquid will be filtered by the filter plate 19 and enter the area below the filter plate 19. Finally, it will enter the water tank 6 through the circulation pipe 8 for recycling, further reducing costs.

[0047] A cleaning method for a hybrid liquid ammonia evaporator, comprising the following steps:

[0048] S100, fill the collection tank 9 with water, open the gas valve of the third pipe 16 to inject nitrogen into the liquid ammonia evaporator 1, replace the ammonia in the liquid ammonia evaporator 1, the water in the collection tank 9 absorbs the ammonia, and the nitrogen enters the nitrogen chamber 13 from the first pipe 10.

[0049] S200, close the gas valve of the third pipeline 16, fill the water tank 6 with water, turn on the pump, and water enters the coil of the liquid ammonia evaporator 1 to flush the inside of the coil.

[0050] S300, open the water valve of the pipe connecting the collection tank 9 and the ammonia tank 18, so that the liquid in the collection tank 9 flows into the ammonia tank 18.

[0051] S400, turn on the heating block 20 to heat the liquid in the ammonia tank 18. The liquid in the ammonia tank 18 is filtered and heated to generate ammonia gas. The ammonia gas enters the ammonia chamber 14 through the second pipe 11. Then the liquid enters the water tank 6 again through the circulation pipe 8. Repeat the above operation multiple times.

[0052] S500, cleaning complete. Turn off the pump in water tank 6, open the gas valve in the fourth pipe 17, and inject ammonia gas into the coil of liquid ammonia evaporator 1.

[0053] The specific process of S200 is as follows: the pump is started to increase the water pressure. When the water enters the coil inlet 3 from the inner cavity of the outer tube 4, it will exert pressure on the sealing plate 21. The spring 22 contracts, and a gap is created between the sealing plate 21 and the outer tube 4. The water flows into the coil of the liquid ammonia evaporator 1 from the gap.

[0054] The above-described embodiments are merely illustrative of certain implementations of the present invention, and are described in a relatively specific and detailed manner. However, they should not be construed as limiting the scope of the present invention. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these modifications and improvements are all within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the appended claims.

Claims

1. A cleaning device for a hybrid liquid ammonia evaporator, characterized in that: Comprising a liquid ammonia evaporator (1), a U-shaped plate (2), a coil inlet (3), an outer tube (4), an inner tube (5), a water tank (6), a discharge pipe (7), a collection tank (9), a gas tank (12) and an ammonia water tank (18); One end of said outer tube (4) is fixedly connected to the coil inlet (3), said coil inlet (3) is fixedly connected to the liquid ammonia evaporator (1), spring bottom plates (23) are arranged in an array on the inner wall of said coil inlet (3), springs (22) are fixedly connected to the outer wall of said spring bottom plates (23), a sealing sheet (21) is arranged in the inner cavity of said coil inlet (3), said sealing sheet (21) is closely attached to the end plane of the outer tube (4) by the thrust of the springs (22), said sealing sheet (21) is used for preventing gas from entering the inner cavity of the outer tube (4), and one end of said outer tube (4) is flush with one end of the inner tube (5); Said outer tube (4) passes through the outer wall of the U-shaped plate (2) and is fixedly connected to the water tank (6), said inner tube (5) penetrates the water tank (6) and passes through the U-shaped plate (2), said water tank (6) is provided with a pump for increasing the flow speed of liquid, a third pipeline (16) and a fourth pipeline (17) are fixedly connected to the outer wall of said inner tube (5), said third pipeline (16) is used for circulating nitrogen gas, and said fourth pipeline (17) is used for circulating ammonia gas; Said gas tank (12) is fixedly mounted on the outer wall of the U-shaped plate (2), said gas tank (12) comprises a partition plate (15), said partition plate (15) divides the inner cavity of the gas tank (12) into two chambers, which are a nitrogen chamber (13) and an ammonia gas chamber (14) respectively, the bottom of said third pipeline (16) communicates with the nitrogen chamber (13), the bottom of said fourth pipeline (17) communicates with the ammonia gas chamber (14), and both said third pipeline (16) and said fourth pipeline (17) are provided with gas valves for accelerating gas circulation; A first pipeline (10) and a second pipeline (11) are fixedly connected to the bottom of said gas tank (12), said first pipeline (10) communicates with the nitrogen chamber (13), said second pipeline (11) communicates with the ammonia gas chamber (14), one end of said first pipeline (10) is fixedly connected to the top of the collection tank (9), and one end of said second pipeline (11) is fixedly connected to the top of the ammonia water tank (18).

2. The cleaning device for a mixed liquid ammonia evaporator according to claim 1, characterized in that: The centers of the horizontal ends of said coil inlet (3), said sealing sheet (21), said outer tube (4) and said inner tube (5) are all on the same axis, the radii of said sealing sheet (21), said outer tube (4) and said inner tube (5) are R1, R2 and R3 respectively, satisfying R3 < R1 < R2, a through hole is provided at the center of said sealing sheet (21), the radius of said through hole is r1, the inner cavity radii of said outer tube (4) and said inner tube (5) are r2 and r3 respectively, satisfying r3 < r1 < R3 and r2 < R1.

3. The cleaning device for a mixed liquid ammonia evaporator according to claim 1, characterized in that: One end of said discharge pipe (7) is fixedly connected to the coil outlet of the liquid ammonia evaporator (1), the other end of said discharge pipe (7) passes through the top of the collection tank (9) and enters the interior of the collection tank (9), said collection tank (9) communicates with the ammonia water tank (18) through a pipeline, and said pipeline is provided with a water valve for opening or closing the pipeline.

4. The cleaning device for a mixed liquid ammonia evaporator according to claim 1, characterized in that: The ammonia tank (18) includes a filter plate (19), a circulation pipe (8), and a heating block (20). The filter plate (19) and the heating block (20) are both located in the inner cavity of the ammonia tank (18). The filter plate (19) is used to filter impurities in the ammonia water. The heating block (20) is used to heat the ammonia water to generate ammonia gas. The inlet of the ammonia tank (18) is higher than the position of the filter plate (19). The outlet of the ammonia tank (18) is lower than the position of the filter plate (19). The outlet of the ammonia tank (18) is connected to the circulation pipe (8). One end of the circulation pipe (8) is connected to the water tank (6). The circulation pipe (8) is used to circulate the liquid in the ammonia tank (18) and the water tank (6).

5. The cleaning method used in the cleaning device for a mixed liquid ammonia evaporator according to any one of claims 1-4, comprising the following steps: S100, fill the collection box (9) with water, open the gas valve of the third pipe (16) to inject nitrogen into the liquid ammonia evaporator (1), replace the ammonia in the liquid ammonia evaporator (1), the water in the collection box (9) absorbs the ammonia, and the nitrogen enters the nitrogen chamber (13) from the first pipe (10). S200, close the gas valve of the third pipe (16), fill the water tank (6) with water, turn on the pump, and water enters the coil of the liquid ammonia evaporator (1) to flush the inside of the coil; S300, open the water valve of the pipe connecting the collection tank (9) and the ammonia tank (18) to allow the liquid in the collection tank (9) to flow into the ammonia tank (18). S400, turn on the heating block (20) to heat the liquid in the ammonia tank (18). The liquid in the ammonia tank (18) is filtered and heated to generate ammonia gas. The ammonia gas enters the ammonia chamber (14) through the second pipe (11). Then the liquid enters the water tank (6) again through the circulation pipe (8). Repeat the above operation multiple times. S500, cleaning complete, turn off the pump of water tank (6), open the gas valve of the fourth pipe (17), and inject ammonia into the coil of liquid ammonia evaporator (1); The specific process of S200 is to start the pump to increase the water pressure. When the water enters the coil inlet (3) from the inner cavity of the outer tube (4), it will exert pressure on the sealing plate (21). The spring (22) will contract, and a gap will be generated between the sealing plate (21) and the outer tube (4). The water will flow into the coil of the liquid ammonia evaporator (1) from the gap.

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