A flue gas circulation system

Abstract

The present invention relates to the technical field of flue gas circulation, and in particular to a flue gas circulation system, which includes a chimney and a waste heat boiler, a back pressure valve and a washing device arranged in the chimney. The upstream end of the waste heat boiler is connected to the exhaust port of the diesel engine, the back pressure valve is arranged on the downstream pipeline of the waste heat boiler, and the downstream end of the back pressure valve is connected to the outside. The washing device includes a first switch valve and N washing towers connected in sequence from top to bottom, and N is a positive integer greater than or equal to 2. The upstream end of the first switch valve is connected to the pipeline between the waste heat boiler and the back pressure valve, and the downstream end of the last-stage washing tower is connected to the air inlet of the diesel engine. Coolant is sprayed in each washing tower to reduce the temperature of the flue gas and remove dust and desulfurization. By arranging N washing towers from top to bottom, the length of the contact space between the flue gas and the coolant can be increased. On the premise of maintaining the cooling and removal efficiency, the tower diameter of the washing tower can be reduced, the occupied area on the horizontal plane can be reduced, and the manufacturing cost can be reduced.

Description

Technical Field

[0001] The invention relates to the technical field of flue gas circulation, and in particular to a flue gas circulation system. Background Art

[0002] Marine diesel engine flue gas needs to be scrubbed to remove pollutants such as sulfur oxides and particulate matter in the flue gas to meet relevant pollutant emission requirements. The scrubbed and cooled flue gas is mixed with air for combustion again. The amount of mixed flue gas can be adjusted to adapt to different operating loads of the diesel engine, and at the same time, the pollutant components in the final exhaust flue gas can be reduced. The scrubber in the existing flue gas circulation system occupies a large area, which is very challenging for the complex cabin space layout.

[0003] Therefore, a flue gas circulation system is urgently needed to solve the above problems. Summary of the invention

[0004] The object of the present invention is to provide a flue gas circulation system which can reduce the occupied area on the horizontal plane and reduce the manufacturing cost while ensuring the cooling and removal efficiency.

[0005] To achieve this object, the present invention adopts the following technical solutions:

[0006] A flue gas circulation system, comprising:

[0007] A waste heat boiler, wherein the upstream end of the waste heat boiler is connected to the exhaust port of the diesel engine;

[0008] A back pressure valve, wherein the back pressure valve is arranged on the downstream pipeline of the waste heat boiler, and the downstream end of the back pressure valve is connected to the outside;

[0009] A washing device, the washing device comprising a first switch valve and N washing towers connected in sequence from top to bottom, N being a positive integer greater than or equal to 2, the upstream end of the first switch valve being connected to the pipeline between the waste heat boiler and the back pressure valve, the downstream end of the last-stage washing tower being connected to the air inlet of the diesel engine, and coolant being sprayed in each of the washing towers to reduce the temperature of the flue gas and remove dust and desulfurization;

[0010] A chimney, wherein the waste heat boiler, the back pressure valve and the washing device are all arranged in the chimney.

[0011] As a preferred embodiment of the flue gas circulation system, it also includes a circulating cooling device, which includes a circulating cabinet, a circulating pump and a heat exchanger that are connected in sequence. The upper end of the circulating cabinet is connected to each of the washing towers to recover the coolant in each of the washing towers. The circulating pump is arranged on a drain pipeline at the lower end of the circulating cabinet, and the drain pipeline is connected to the heat exchange inlet of the heat exchanger. The heat exchange outlet of the heat exchanger is connected to the coolant inlet of each of the washing towers.

[0012] As a preferred solution for the flue gas circulation system, a drain port is provided at the lower end of each washing tower, and each drain port is connected to the circulation cabinet through a pipeline. The circulation cabinet is arranged at a lower position than the last-stage washing tower so that the coolant can flow back to the circulation cabinet.

[0013] As a preferred solution of the flue gas circulation system, a plurality of spray layers are arranged in each of the scrubbing towers, each of the spray layers includes a plurality of nozzles, and each of the nozzles is connected to the coolant inlet.

[0014] As a preferred solution of the flue gas circulation system, the flue gas flows from top to bottom in each of the washing towers, and the coolant is sprayed from bottom to top in each of the washing towers.

[0015] As a preferred solution of the flue gas circulation system, it also includes a demister, which is arranged on the pipeline between the downstream end of the last stage of the washing tower and the air inlet.

[0016] As a preferred solution for the flue gas circulation system, a discharge port is provided on the downstream pipeline of the demister, and the discharge port is connected to the circulation cabinet.

[0017] As a preferred solution of the flue gas circulation system, it also includes a second switch valve, which is arranged on the pipeline between the demister and the air inlet.

[0018] As a preferred solution of the flue gas circulation system, it also includes a muffler, which is arranged on the pipeline connecting the back pressure valve and the outside.

[0019] As a preferred solution of the flue gas circulation system, it also includes a controller, and the controller is electrically connected to the diesel engine, the back pressure valve, the first switch valve, the second switch valve and the circulation pump.

[0020] Beneficial effects of the present invention:

[0021] The present invention provides a flue gas circulation system, comprising a chimney and a waste heat boiler, a back pressure valve and a washing device arranged in the chimney. The upstream end of the waste heat boiler is connected to the exhaust port of the diesel engine, the back pressure valve is arranged on the downstream pipeline of the waste heat boiler, and the downstream end of the back pressure valve is connected to the outside world. That is, when the back pressure valve is opened, the flue gas of the diesel engine can be discharged into the outside environment through the waste heat boiler. The washing device comprises a first switch valve and N washing towers connected in sequence from top to bottom, where N is a positive integer greater than or equal to 2. The upstream end of the first switch valve is connected to the pipeline between the waste heat boiler and the back pressure valve, and the downstream end of the last washing tower is connected to the air inlet of the diesel engine. Coolant is sprayed in each washing tower to reduce the temperature of the flue gas and remove dust and desulfurization. By arranging N washing towers from top to bottom, the length of the contact space between the flue gas and the coolant can be increased, and the diameter of the washing tower can be reduced and the flue gas flow rate can be increased while maintaining the cooling and removal efficiency. That is, compared with the prior art, the flue gas circulation system occupies less area on the horizontal plane, and the difficulty of spatial layout is reduced. At the same time, since multiple small scrubbing towers are used instead of one large scrubbing tower, the manufacturing cost is also reduced accordingly. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 It is a structural schematic diagram of a flue gas circulation system and a diesel engine provided by an embodiment of the present invention;

[0023] Figure 2 It is a structural schematic diagram of a primary washing tower provided in an embodiment of the present invention.

[0024] In the figure:

[0025] 1. Waste heat boiler;

[0026] 2. Diesel engine; 21. Exhaust port; 22. Air inlet;

[0027] 3. Back pressure valve; 4. First switch valve;

[0028] 5. Primary washing tower; 51. First cooling liquid inlet; 52. First liquid discharge outlet; 53. First spray layer; 531. First nozzle;

[0029] 6. Secondary scrubber; 7. Third-stage scrubber; 8. Chimney; 9. Circulation cabinet; 10. Circulation pump;

[0030] 11. heat exchanger; 111. heat exchange inlet; 112. heat exchange outlet;

[0031] 12. Defogger; 13. Drain port; 14. Liquid level sensor; 15. First temperature sensor; 16. Second temperature sensor; 17. Second switch valve; 18. Muffler. DETAILED DESCRIPTION

[0032] The technical solution of the present invention is further described below in conjunction with the accompanying drawings and implementation methods. It is to be understood that the specific embodiments described herein are only used to explain the present invention, rather than to limit the present invention. It should also be noted that, for ease of description, only the parts related to the present invention are shown in the accompanying drawings, rather than all of them.

[0033] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection or a detachable connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, and it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0034] In the present invention, unless otherwise clearly specified and limited, a first feature being "above" or "below" a second feature may include that the first and second features are in direct contact, or may include that the first and second features are not in direct contact but are in contact through another feature between them. Moreover, a first feature being "above", "above" and "above" a second feature includes that the first feature is directly above and obliquely above the second feature, or simply indicates that the first feature is higher in level than the second feature. A first feature being "below", "below" and "below" a second feature includes that the first feature is directly below and obliquely below the second feature, or simply indicates that the first feature is lower in level than the second feature.

[0035] The flue gas of the diesel engine 2 of the ship needs to be washed to remove pollutants such as sulfur oxides and particulate matter in the flue gas to meet the relevant pollutant emission requirements. The washed and cooled flue gas is mixed with air and burned again. The amount of mixed flue gas can be adjusted to adapt to the different operating loads of the diesel engine 2, and at the same time, the pollutant components in the final exhaust flue gas can be reduced. The washing tower in the existing flue gas circulation system occupies a large area. The washing tower is placed outside the chimney 8, and the diameter of the washing tower is about 2.5 times the diameter of the chimney 8. The horizontal size of the washing tower is too large, which is very challenging for the complex cabin space layout. Therefore, this embodiment provides a flue gas circulation system to solve the above problems.

[0036] like Figure 1 As shown, the flue gas circulation system includes a chimney 8 and a smoke exhaust device and a washing device arranged in the chimney 8.

[0037] The smoke exhaust device includes a waste heat boiler 1, a back pressure valve 3 and a muffler 18 which are connected in sequence. The upstream end of the waste heat boiler 1 is connected to the smoke exhaust port 21 of the diesel engine 2. The back pressure valve 3 is arranged on the downstream pipeline of the waste heat boiler 1. The downstream end of the muffler 18 is connected to the outside. That is, when the back pressure valve 3 is opened, the smoke of the diesel engine 2 can be discharged to the outside environment through the waste heat boiler 1 and the muffler 18.

[0038] The washing device includes a first switch valve 4 and N washing towers connected in sequence from top to bottom, where N is a positive integer greater than or equal to 2. The upstream end of the first switch valve 4 is connected to the pipeline between the waste heat boiler 1 and the back pressure valve 3, and the downstream end of the last-stage washing tower is connected to the air inlet 22 of the diesel engine 2. Coolant is sprayed in each washing tower to reduce the temperature of the flue gas and remove dust and desulfurize the flue gas. Preferably, the flue gas circulation system also includes a second switch valve 17, which is arranged on the pipeline between the last-stage washing tower and the air inlet 22 of the diesel engine 2 to control the flue gas flow entering the diesel engine 2.

[0039] By arranging N scrubbers from top to bottom, the length of the contact space between the flue gas and the coolant can be increased. Under the premise of maintaining the cooling and removal efficiency, the diameter of the scrubber can be reduced and the flue gas flow rate can be increased. That is, compared with the prior art, the occupied area of ​​the flue gas circulation system on the horizontal plane is reduced, and the difficulty of spatial layout is reduced. At the same time, due to the use of multiple small scrubbers instead of one large scrubber, its manufacturing cost is also reduced accordingly.

[0040] Optionally, in this embodiment, N is 3, that is, the scrubbing device includes a primary scrubber 5, a secondary scrubber 6, and a tertiary scrubber 7. The flue gas temperature downstream of the waste heat boiler 1 is in the range of 180-200°C. After passing through the primary scrubber 5, the flue gas is cooled to about 60-80°C. After passing through the secondary scrubber 6, the flue gas is cooled to about 40-60°C. After passing through the tertiary scrubber 7, the flue gas is cooled to about 30-40°C. The flue gas at this temperature can meet the temperature requirement of the diesel engine 2 for circulating flue gas.

[0041] In order to circulate the coolant, preferably, the flue gas circulation system also includes a circulating cooling device. The circulating cooling device includes a circulating cabinet 9, a circulating pump 10 and a heat exchanger 11 which are connected in sequence. The upper end of the circulating cabinet 9 is connected to each washing tower to recover the coolant in each washing tower. The circulating pump 10 is arranged on the discharge pipeline at the lower end of the circulating cabinet 9 to provide the power required for the circulation of the coolant and the spraying in the washing tower. Optionally, the circulating pump 10 is a variable frequency pump to adjust the circulation flow of the coolant in real time. The discharge pipeline is connected to the heat exchange inlet 111 of the heat exchanger 11, and the coolant enters the heat exchanger 11 for cooling. The heat exchange outlet 112 of the heat exchanger 11 is connected to the coolant inlet of each washing tower to input the cooled coolant into the washing tower.

[0042] Preferably, a drain port is provided at the lower end of each washing tower, and each drain port is connected to the circulation cabinet 9 through a pipeline. The circulation cabinet 9 is arranged at a lower position than the last-stage washing tower so that the coolant can flow back to the circulation cabinet 9. Optionally, a tapered pipe is provided at the drain port to ensure smooth discharge of the coolant.

[0043] In order to prevent the coolant from flowing into the downstream flue gas pipeline or washing tower, optionally, the exhaust port of each stage of the washing tower is arranged at the lower side wall to ensure that the flue gas flows from top to bottom to the exhaust port.

[0044] In order to ensure that the flue gas and the coolant are fully mixed and heat exchanged, and to ensure the dust removal and desulfurization efficiency, preferably, each scrubber is provided with multiple spray layers, each spray layer includes multiple nozzles, and each nozzle is connected to the coolant inlet. The nozzles are evenly distributed on the spray layer to ensure that the coolant is evenly atomized in the scrubber and increase the contact area with the flue gas.

[0045] In order to further enhance the heat exchange effect between the flue gas and the coolant, preferably, the flue gas flows from top to bottom in each washing tower, and the coolant is sprayed from bottom to top in each washing tower. It is known that the countercurrent flow of the flue gas and the coolant spray can effectively improve the heat exchange and removal efficiency of the flue gas.

[0046] like Figure 2 As shown, taking the primary washing tower 5 as an example, the first cooling liquid pipeline is arranged through the side wall of the primary washing tower 5, and the first cooling liquid inlet 51 is arranged in the first cooling liquid pipeline. Three first spray layers 53 are arranged in the primary washing tower 5, and each first spray layer 53 is provided with a plurality of first nozzles 531. The first cooling liquid pipeline is connected with the inner cavity of the first spray layer 53, and the cooling liquid can be sprayed evenly in the primary washing tower 5 from the inner cavity of the first spray layer 53 through the first nozzle 531.

[0047] After being washed by the multi-stage washing tower, the flue gas will carry liquid droplets and will be further cooled in the pipeline flowing from the third-stage washing tower 7 to the air inlet 22 of the diesel engine 2, and condensed water will be formed on the inner wall of the pipeline. Preferably, the flue gas circulation system also includes a demister 12, and the demister 12 is arranged on the pipeline between the downstream end of the last-stage washing tower and the air inlet 22. Optionally, the demister 12 adopts a flat-plate corrugated demister, and the advantage of the flat-plate corrugated demister is that the structure is small in size and can adapt to the smaller pipeline size here. The droplets in the flue gas collide with the baffles of the flat-plate corrugated demister, and the droplets condense and grow, and can be captured by the plate corrugations, thereby reducing the amount of droplets carried by the flue gas to meet the humidity requirements of the diesel engine 2 for the flue gas.

[0048] Preferably, a discharge port 13 is provided on the downstream pipeline of the demister 12, and the discharge port 13 is connected to the circulation cabinet 9. The droplets captured by the demister 12 can be discharged from the pipeline from the discharge port 13 and enter the circulation cabinet 9 for recycling. Optionally, a liquid level sensor 14 is also provided in the discharge port 13 to monitor whether the amount of droplets carried in the flue gas is too much. When the amount of droplets carried is too much, the circulation flow rate of the coolant needs to be reduced, and the temperature of the coolant needs to be reduced to ensure that the temperature and water content of the flue gas entering the diesel engine 2 meet the requirements.

[0049] In order to monitor the flue gas temperature in real time, preferably, a first temperature sensor 15 is provided on the pipeline between the first switch valve 4 and the primary scrubber 5 to understand the flue gas temperature before scrubbing. A second temperature sensor 16 is provided on the pipeline between the demister 12 and the second switch valve 17 to understand the flue gas temperature entering the diesel engine 2.

[0050] In order to realize the automatic control of flue gas temperature and humidity, preferably, the flue gas circulation system also includes a controller. The controller is electrically connected to the diesel engine 2, the back pressure valve 3, the first switch valve 4, the second switch valve 17 and the circulation pump 10. The controller can obtain the required circulating flue gas flow rate according to the operating load of the diesel engine 2, and adjust the opening and closing and opening of the back pressure valve 3, the first switch valve 4 and the second switch valve 17 to control the proportion of the circulating flue gas in the total exhaust flue gas. At the same time, the controller can also control the operation of the circulation pump 10 according to the circulating flue gas flow rate to adjust the flow rate of the coolant to ensure the cooling and dust removal and desulfurization effect of the flue gas. Preferably, the controller is electrically connected to the liquid level sensor 14, the first temperature sensor 15, and the second temperature sensor 16. The controller can control the circulation pump 10 to adjust the circulation flow rate of the coolant according to the temperature of the flue gas before and after washing, and the droplet carrying amount of the flue gas.

[0051] Obviously, the above embodiments of the present invention are merely examples for clearly illustrating the present invention, and are not intended to limit the embodiments of the present invention. For those skilled in the art, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to list all the embodiments here. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the claims of the present invention.

Claims

1. A flue gas circulation system, characterized in that: include: A waste heat boiler (1), wherein the upstream end of the waste heat boiler (1) is connected to a smoke exhaust port (21) of a diesel engine (2); A back pressure valve (3), wherein the back pressure valve (3) is arranged on a downstream pipeline of the waste heat boiler (1), and a downstream end of the back pressure valve (3) is in communication with the outside; A washing device, the washing device comprising a first switch valve (4) and N washing towers connected in sequence from top to bottom, N being a positive integer greater than or equal to 2, the upstream end of the first switch valve (4) being connected to the pipeline between the waste heat boiler (1) and the back pressure valve (3), the downstream end of the last stage of the washing tower being connected to the air inlet (22) of the diesel engine (2), each of the washing towers being sprayed with coolant to reduce the temperature of the flue gas and remove dust and desulfurization, and by arranging the N washing towers from top to bottom, the length of the contact space between the flue gas and the coolant can be increased; A chimney (8), wherein the waste heat boiler (1), the back pressure valve (3) and the scrubbing device are all arranged in the chimney (8) to reduce the occupied area of ​​the flue gas circulation system on a horizontal plane; It also includes a circulating cooling device, the circulating cooling device including a circulating cabinet (9), a circulating pump (10) and a heat exchanger (11) which are connected in sequence, the upper end of the circulating cabinet (9) is connected to each of the washing towers to recover the cooling liquid in each of the washing towers, the circulating pump (10) is arranged on a drainage pipeline at the lower end of the circulating cabinet (9), the drainage pipeline is connected to a heat exchange inlet (111) of the heat exchanger (11), and the heat exchange outlet (112) of the heat exchanger (11) is connected to the cooling liquid inlet of each of the washing towers; The flue gas flows from top to bottom in each of the washing towers, and the coolant is sprayed from bottom to top in each of the washing towers.

2. The flue gas circulation system according to claim 1, characterized in that: A drain port is provided at the lower end of each washing tower, and each drain port is connected to the circulation cabinet (9) through a pipeline. The circulation cabinet (9) is arranged at a position lower than that of the last-stage washing tower so that the coolant can flow back to the circulation cabinet (9).

3. The flue gas circulation system according to claim 1, characterized in that: A plurality of spray layers are arranged in each of the washing towers, each of the spray layers comprises a plurality of nozzles, and each of the nozzles is connected to the coolant inlet.

4. The flue gas circulation system according to claim 1, characterized in that: It also comprises a demister (12), wherein the demister (12) is arranged on the pipeline between the downstream end of the last stage of the washing tower and the air inlet (22).

5. The flue gas circulation system according to claim 4, characterized in that: A discharge port (13) is provided on the downstream pipeline of the demister (12), and the discharge port (13) is connected to the circulation cabinet (9).

6. The flue gas circulation system according to claim 4, characterized in that: It also includes a second switch valve (17), which is arranged on the pipeline between the demister (12) and the air inlet (22).

7. The flue gas circulation system according to claim 1, characterized in that: It also includes a muffler (18), which is arranged on a pipeline connecting the back pressure valve (3) with the outside.

8. The flue gas circulation system according to claim 6, characterized in that: It also includes a controller, which is electrically connected to the diesel engine (2), the back pressure valve (3), the first switch valve (4), the second switch valve (17) and the circulation pump (10).

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