CN114909236A

CN114909236A - Multistage cooling tower and low pressure EGR system

Info

Publication number: CN114909236A
Application number: CN202210660404.8A
Authority: CN
Inventors: 张文博; 李海艳; 蔡少林; 吴朝晖; 陶国华; 李大保; 刘博�; 刘利军; 张继光; 韩连任; 周秀亚; 田新娜; 王雁冰; 王园
Original assignee: China Shipbuilding Power Engineering Institute Co Ltd
Current assignee: China Shipbuilding Power Engineering Institute Co Ltd
Priority date: 2022-06-13
Filing date: 2022-06-13
Publication date: 2022-08-16
Anticipated expiration: 2042-06-13
Also published as: CN114909236B

Abstract

The invention relates to the technical field of exhaust gas circulation and discloses a multistage cooling tower and a low-pressure EGR system. The multistage cooling tower comprises a plurality of cooling parts and a demisting part which are sequentially communicated. Every cooling portion all is including a spray section and a section of bleeding that is linked together, and a plurality of spray sections are parallel to each other, and a plurality of sections of bleeding are parallel to each other, and the spray section and the section of bleeding of every cooling portion all are the contained angle setting, and this contained angle is a, and 80 is ≤ a ≤ 100 to when reducing the multistage cooling tower volume, the loss of the gaseous dynamic pressure head of waste is avoided to the at utmost. The spray section includes the spray line and sprays the piece, and the section of bleeding is including the pipeline of bleeding and the piece of bleeding, sprays the piece and is used for spraying the cooling water in to the spray line, and the piece of bleeding is used for bleeding the cooling water that flows in the pipeline of bleeding, and waste gas can flow through a plurality of spray lines in proper order and the pipeline of bleeding, realizes multistage cooling and washing, and the cooling water of avoiding this cooling portion flows into next cooling portion through the pipeline of bleeding to influence next cooling portion performance.

Description

Multistage cooling tower and low pressure EGR system

Technical Field

The invention relates to the technical field of exhaust gas circulation, in particular to a multistage cooling tower and a low-pressure EGR system.

Background

The routes of exhaust gas recirculation of marine engines are divided into two routes, namely a high-pressure route and a low-pressure route. The high-pressure route leads air from the front of an exhaust gas suction port of the turbocharger, cools and washes the exhaust gas, removes water drops in the gas, further pressurizes the gas by a blower and then enters a scavenging manifold. The low-pressure route leads air from the exhaust outlet of the turbocharger, cools and washes the exhaust gas, removes water drops in the gas and then enters the air suction port of the compressor of the turbocharger. The exhaust gas recirculation device of the low-pressure route has the defects that the volume of a cooling washing device in the exhaust gas recirculation process is overlarge due to low exhaust gas pressure and low density, the cooling washing device is difficult to arrange in a cabin, and the exhaust gas recirculation device of the low-pressure route is difficult to popularize and apply.

Therefore, a need exists for a multi-stage cooling tower and low pressure EGR system that addresses the above issues.

Disclosure of Invention

An object of the present invention is to provide a multistage cooling tower which is small in size, occupies a small space, and can be flexibly arranged.

As the conception, the technical scheme adopted by the invention is as follows:

a multi-stage cooling tower comprising:

the cooling part is provided with a plurality of cooling parts which are sequentially communicated, each cooling part comprises a spraying section and a discharging section which are communicated, the spraying sections are mutually parallel, the discharging sections are mutually parallel, the spraying section and the discharging section of each cooling part are arranged in an included angle, the included angle is a, and a is more than or equal to 80 degrees and less than or equal to 100 degrees;

the spraying section comprises a spraying pipeline and a spraying piece, the discharging section comprises a discharging pipeline and a discharging piece, the spraying piece is used for spraying cooling water into the spraying pipeline, and the discharging piece is used for discharging the cooling water flowing into the discharging pipeline;

and the defogging part is provided with one, the defogging part is communicated with the tail ends of the plurality of cooling parts which are sequentially communicated, the head end of the multistage cooling tower is the spraying section, the tail end of the multistage cooling tower is the defogging part, and the defogger is arranged on the defogging part.

Optionally, in an axial direction of the drain line, the drain of each cooling portion is disposed at an end of the drain line close to the spray line.

Optionally, a discharge port is arranged on the discharge pipeline, the discharge member is communicated with the discharge pipeline through the discharge port, the perimeter of the discharge pipeline is b, the diameter of the discharge port is c, and b/5 is less than or equal to c and less than or equal to b/4.

Optionally, the vent member is a conical structure, a large-diameter end of the conical structure is connected to the vent port, and a small-diameter end of the conical structure is connected to the external circulation pipeline.

Optionally, the demister is disposed at a small-diameter end of the diffusion pipeline, and the demister is disposed at a large-diameter end of the diffusion pipeline.

Optionally, the spraying pipeline, the discharge pipeline and the diffusion pipeline are all communicated through a spliced elbow.

Optionally, the spraying part is provided with a plurality of layers, the plurality of layers of spraying parts are arranged along the axial direction of the spraying pipeline at intervals, each layer of spraying part is provided with a plurality of spraying parts, and the plurality of spraying parts are arranged along the circumferential direction of the spraying pipeline at intervals.

Optionally, the spraying pipeline and the discharge pipeline are vertically arranged, the spraying pipeline is vertically arranged, and the discharge pipeline is horizontally arranged.

Another object of the present invention is to provide a low pressure EGR system, which is easy to arrange in the nacelle and has high applicability.

As the conception, the technical scheme adopted by the invention is as follows:

a low-pressure EGR system comprises the multistage cooling tower.

Optionally, the low-pressure EGR system further includes a turbocharger and an exhaust gas waste heat boiler, one end of the exhaust gas waste heat boiler is communicated with an exhaust gas outlet of the turbocharger, the other end of the exhaust gas waste heat boiler is communicated with a head end of the multistage cooling tower, and a tail end of the multistage cooling tower is communicated with an air inlet of the turbocharger.

The invention has the beneficial effects that:

the multistage cooling tower provided by the invention comprises a plurality of cooling parts which are sequentially communicated, each cooling part comprises a spraying section and a discharging section which are communicated, the spraying sections are mutually parallel, the discharging sections are mutually parallel, the spraying section and the discharging section of each cooling part are arranged in an included angle, the included angle is a, a is more than or equal to 80 degrees and less than or equal to 100 degrees, and the loss of the dynamic pressure head of waste gas can be avoided to the maximum extent while the volume of the multistage cooling tower is reduced. In addition, the spray segment includes the spray pipe way and sprays the piece, the section of bleeding includes the pipeline of bleeding and the piece of bleeding, the piece of spraying is used for spraying the cooling water in to the spray pipe way, the piece of bleeding is used for bleeding the cooling water that flows into in the pipeline of bleeding, waste gas can flow through a plurality of spray pipes and the pipeline of bleeding in proper order, in order to realize multistage cooling and washing, make the cooling water of this cooling portion can not flow into next cooling portion through the pipeline of bleeding simultaneously, avoid influencing the performance of next cooling portion, in order to guarantee multistage cooling tower to the cooling and the washing effect of waste gas. In addition, the multistage cooling tower also comprises a demisting part communicated with the tail ends of the plurality of cooling parts which are sequentially communicated, so that the multistage cooling tower with the spraying section at the head end and the demisting part at the tail end is formed, and waste gas can be cooled and washed and then recycled.

The low-pressure EGR system provided by the invention comprises the multistage cooling tower, has a small volume, is convenient to arrange in a cabin, and has high applicability.

Drawings

FIG. 1 is a schematic diagram of a multi-stage cooling tower according to an embodiment of the present invention;

fig. 2 is a schematic structural diagram of a low-pressure EGR system according to an embodiment of the present invention.

In the figure:

1. a cooling section; 11. a spraying section; 111. a spray pipeline; 112. a spraying member; 12. a bleed-off section; 121. a bleed line; 122. a bleed member; 13. splicing the elbows; 2. a defogging section; 21. a diffusion pipeline; 22. a demister; 23. a tapered pipeline;

100. a multi-stage cooling tower; 200. a turbocharger; 300. a waste gas exhaust-heat boiler; 400. a diesel engine.

Detailed Description

In order to make the technical problems solved, the technical solutions adopted and the technical effects achieved by the present invention clearer, the technical solutions of the present invention are further described below by way of specific embodiments with reference to the accompanying drawings. It is to be understood that the specific embodiments described herein are merely illustrative of the invention and are not limiting of the invention. It should be further noted that, for the convenience of description, only some but not all of the elements associated with the present invention are shown in the drawings.

In the description of the present invention, unless expressly stated or limited otherwise, the terms "connected," "connected," and "fixed" are to be construed broadly, e.g., as meaning permanently connected, removably connected, or integral to one another; can be mechanically or electrically connected; either directly or indirectly through intervening media, either internally or in any other relationship. The specific meanings of the above terms in the present invention can be understood in specific cases to those skilled in the art.

In the present invention, unless otherwise expressly stated or limited, "above" or "below" a first feature means that the first and second features are in direct contact, or that the first and second features are not in direct contact but are in contact with each other via another feature therebetween. Also, the first feature being "on," "above" and "over" the second feature includes the first feature being directly on and obliquely above the second feature, or merely indicating that the first feature is at a higher level than the second feature. A first feature being "under," "below," and "beneath" a second feature includes the first feature being directly under and obliquely below the second feature, or simply meaning that the first feature is at a lesser elevation than the second feature.

In the description of the present embodiment, the terms "upper", "lower", "left", "right", and the like are used based on the orientations and positional relationships shown in the drawings, and are only for convenience of description and simplicity of operation, but do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and thus, should not be construed as limiting the present invention. Furthermore, the terms "first" and "second" are used only for descriptive purposes and are not intended to have a special meaning.

The technical scheme of the invention is further explained by the specific implementation mode in combination with the attached drawings.

When the ship engine burns the ship fuel, an Exhaust Gas Recirculation (EGR) system can reduce the oxygen concentration in scavenging air of the engine, thereby reducing the highest combustion temperature of a combustion chamber of the engine, and enabling the NOx emission of the engine to meet the emission requirement of IMO Tier 3. When the ship engine burns LNG (Liquefied Natural Gas) fuel, the exhaust Gas recirculation system can also reduce the scavenging oxygen concentration of the engine, so that the combustion of the Liquefied Natural Gas is more stable, the phenomena of fire catching and deflagration of the engine are avoided, the fuel Gas consumption rate can be reduced, and the escape of methane is reduced. The exhaust gas recirculation system enables exhaust gas generated by the engine to be cooled and washed by the cooling and washing device and then the engine can be carried out again, but for the low-pressure exhaust gas recirculation system of the ship engine, the exhaust gas is led from the exhaust gas outlet of the turbocharger 200, namely the exhaust gas is low in pressure and density, so that the cooling and washing device required by the exhaust gas recirculation system is overlarge in size and difficult to arrange in a cabin, and the popularization and application of the exhaust gas recirculation system of a low-pressure route are seriously influenced.

The embodiment provides a multistage cooling tower 100, which not only has small dynamic pressure loss of waste gas and fast flow speed of waste gas, but also can make full use of pipeline space, so that the volume of the multistage cooling tower 100 is reduced, and the arrangement and application of an exhaust gas recirculation system are more convenient. The multistage cooling tower 100 includes a plurality of cooling portions 1 that are sequentially communicated, and for adapting to the exhaust gas discharge capacity of the existing engine, the multistage cooling tower 100 is generally provided with three-stage cooling and more, that is, the number of the cooling portions 1 is three and more. In this embodiment, three-stage cooling is exemplified.

As shown in fig. 1, each cooling portion 1 includes a spray section 11 and a discharge section 12 that are communicated with each other, that is, after the exhaust gas enters the multistage cooling tower 100, the exhaust gas will pass through the spray section 11, the discharge section 12, and so on in sequence, and in order to reduce the volume of the multistage cooling tower 100, the spray section 11 and the discharge section 12 of each cooling portion 1 are arranged at an included angle, but the spray sections 11 are parallel to each other, and the discharge sections 12 are parallel to each other. Optionally, the included angle between the axial direction of the spraying section 11 and the axial direction of the discharge section 12 is a, 80 DEG-100 DEG, which can avoid the loss of the dynamic head of the exhaust gas to the maximum extent. Wherein the air velocity in the multistage cooling tower 100 before the cooling of the exhaust gas is about 20m/s, the air velocity in the multistage cooling tower 100 after the cooling of the exhaust gas is about 14m/s, the temperature of the exhaust gas before the exhaust gas enters the multistage cooling tower 100 is about 180 ℃, the temperature of the exhaust gas is reduced to below 60 ℃ after the exhaust gas passes through one cooling part 1, and the temperature of the exhaust gas is reduced to below 40 ℃ after the exhaust gas passes through a plurality of cooling parts 1. The multistage cooling tower 100 further comprises a defogging portion 2, the defogging portion 2 is provided with one, the defogging portion 2 is communicated with the tail ends of the multiple cooling portions 1 which are sequentially communicated, wherein the tail end of the cooling portion 1 is a discharge section 12, and the head end of the cooling portion 1 is a spray section 11. That is, the exhaust gas is sequentially cooled and washed by the plurality of cooling units 1, and finally enters the demisting unit 2, that is, the first end of the multistage cooling tower 100 is the spray section 11, and the tail end of the multistage cooling tower 100 is the demisting unit 2. The demister 22 is provided in the demister 2, and the demister 22 further collects mist particles, slurry, and the like in the exhaust gas to make the exhaust gas meet the standard of recirculation.

Each spray segment 11 includes a spray pipe 111 and a spray member 112, and each drain segment 12 includes a drain pipe 121 and a drain member 122, the spray pipe 111 and the drain pipe 121 being sequentially communicated so that the offgas may sequentially pass through the plurality of cooling portions 1. The spray member 112 is disposed on the spray pipe 111 and is capable of spraying cooling water into the spray pipe 111 to cool and wash the exhaust gas, and the drain member 122 is disposed on the drain pipe 121 and is configured to drain the cooling water flowing into the drain pipe 121, so as to prevent the cooling water of this cooling part 1 from flowing into the next cooling part 1 through the drain pipe 121 and affecting the performance of the next cooling part 1, thereby ensuring the cooling and washing effects of the multistage cooling tower 100 on the exhaust gas.

Preferably, the spraying member 112 is provided with a plurality of layers, the plurality of layers of spraying members 112 are arranged at intervals along the axial direction of the spraying pipeline 111, a plurality of spraying members 112 are arranged on each layer of spraying member 112, and the plurality of spraying members 112 are arranged at intervals along the circumferential direction of the spraying pipeline 111 to ensure the uniformity of spraying.

Further, in order to ensure that the drain pipeline 121 can timely drain the cooling water, the drain piece 122 of each cooling portion 1 is disposed at one end of the drain pipeline 121 close to the spraying pipeline 111 along the axial direction of the drain pipeline 121. In addition, considering the flow velocity and direction of the exhaust gas and the cooling water, the drain 122 should communicate with a side of the drain 121 facing away from the shower pipe 111 in a radial direction of the drain 121. In the exhaust gas circulation process, the exhaust gas flows in the upper layer in the spray pipe 111, and the cooling water flows in the lower layer of the exhaust gas in the spray pipe 111, so that the flowing cooling water can realize dynamic sealing of the drain 122, and the exhaust gas is prevented from flowing out of the cooling part 1 through the drain 122.

Furthermore, a discharge port is arranged on the discharge pipeline 121, the discharge member 122 is communicated with the discharge pipeline 121 through the discharge port, the diameter of the discharge port is determined according to the circumference of the discharge pipeline 121, the circumference of the discharge pipeline 121 is b, the diameter of the discharge port is c, and b/5 is not less than c and not more than b/4. Preferably, c is equal to b/4. In addition, in order to communicate with the release opening and ensure the outflow of the cooling water, the release member 122 is set to be of a conical structure, the large-diameter end of the conical structure is connected to the release opening, and the small-diameter end of the conical structure is connected to the external circulation pipeline.

In this embodiment, the spraying pipe 111 and the discharging pipe 121 are vertically arranged, the spraying pipe 111 is vertically arranged, and the discharging pipe 121 is horizontally arranged, that is, as shown in fig. 1, a is 90 ° in this embodiment.

The demister 2 includes a diffuser 21, the diffuser 21 is a reducer, the small diameter end of the reducer is communicated with the drain 121, and the demister 22 is disposed at the large diameter end. Because the highest adaptive gas velocity of the demister 22 is about 6m/s, and the gas velocity of the waste gas after multi-stage cooling is about 14m/s, the waste gas can be decelerated in the diffusion pipeline 21 by adopting a reducer pipe for the diffusion pipeline 21. Optionally, the demister 2 further includes a tapered pipe 23, a large diameter end of the tapered pipe 23 is communicated with the demister 22, and a small diameter end of the tapered pipe 23 is communicated with the turbocharger 200 through a system pipe, that is, the large diameter of the tapered pipe 23 is determined according to the demister 22, and the small diameter of the tapered pipe 23 is determined according to the system pipe.

Alternatively, to reduce the head loss of the exhaust gas in the multistage cooling tower 100, and based on the actual pipe diameter size of the multistage cooling tower 100, the spray pipe 111, the bleed pipe 121, and the diffuser pipe 21 are communicated through the spliced elbow 13.

The present embodiment also provides a low pressure EGR system including the multi-stage cooling tower 100 described above, which is small in size and convenient to arrange in a cabin.

As shown in fig. 2, the low-pressure EGR system further includes a turbocharger 200 and an exhaust gas heat recovery boiler 300, one end of the exhaust gas heat recovery pipeline is connected to the exhaust gas outlet of the turbocharger 200, the other end is connected to the head end of the multistage cooling tower 100, and the exhaust gas at the tail end of the multistage cooling tower 100 is connected to the air inlet of the turbocharger 200. That is, the high-temperature exhaust gas discharged from the diesel engine 400 enters the exhaust gas duct from the exhaust gas outlet of the turbocharger 200, and first enters the exhaust gas waste heat boiler 300 for waste heat utilization, and then a part of the exhaust gas is discharged to the atmosphere in a straight manner, and the other part of the exhaust gas enters the multistage cooling tower 100. The exhaust gas is cooled, washed and filtered in the multistage cooling tower 100 to remove moisture from the exhaust gas, and then enters the turbocharger 200.

The foregoing embodiments are merely illustrative of the principles and features of this invention, which is not limited to the above-described embodiments, but rather is susceptible to various changes and modifications without departing from the spirit and scope of the invention, which changes and modifications are within the scope of the invention as claimed. The scope of the invention is defined by the appended claims and equivalents thereof.

Claims

1. A multi-stage cooling tower, comprising:

the cooling part (1) is provided with a plurality of cooling parts (1) which are sequentially communicated, each cooling part (1) comprises a spraying section (11) and a discharge section (12) which are communicated, the spraying sections (11) are parallel to each other, the discharge sections (12) are parallel to each other, the spraying section (11) and the discharge section (12) of each cooling part (1) are arranged at an included angle, and the included angle is a, wherein a is more than or equal to 80 degrees and is less than or equal to 100 degrees;

the spray section (11) comprises a spray pipeline (111) and a spray piece (112), the discharge section (12) comprises a discharge pipeline (121) and a discharge piece (122), the spray piece (112) is used for spraying cooling water into the spray pipeline (111), and the discharge piece (122) is used for discharging the cooling water flowing into the discharge pipeline (121);

defogging portion (2), be provided with one, defogging portion (2) communicate in a plurality of that communicate in proper order the end of cooling portion (1), and make the head end of multistage cooling tower (100) does spray section (11), the end of multistage cooling tower (100) does defogging portion (2), defogging portion (2) are provided with defroster (22).

2. The multistage cooling tower according to claim 1, wherein the drain (122) of each cooling section (1) is provided at an end of the drain (121) near the shower line (111) in an axial direction of the drain line (121).

3. The multistage cooling tower according to claim 2, wherein a discharge port is arranged on the discharge pipeline (121), the discharge member (122) is communicated with the discharge pipeline (121) through the discharge port, the circumference of the discharge pipeline (121) is b, the diameter of the discharge port is c, and b/5 is larger than or equal to c and smaller than or equal to b/4.

4. The multi-stage cooling tower according to claim 3, wherein the drain (122) is a cone structure, and a large diameter end of the cone structure is connected to the drain, and a small diameter end of the cone structure is connected to an external circulation line.

5. The multistage cooling tower according to claim 1, wherein the demister (2) comprises a diffuser pipe (21), a small-diameter end of the diffuser pipe (21) is communicated with the drain pipe (121), and a large-diameter end of the diffuser pipe (21) is provided with the demister (22).

6. The multistage cooling tower according to claim 5, wherein the spray line (111), the bleed line (121) and the diffuser line (21) all communicate via a spliced elbow (13).

7. The multistage cooling tower according to claim 1, wherein the spray member (112) is provided in a plurality of layers, the plurality of layers of spray members (112) are arranged at intervals in the axial direction of the spray pipe (111), a plurality of spray members (112) are provided in each layer, and a plurality of spray members (112) are arranged at intervals in the circumferential direction of the spray pipe (111).

8. The multi-stage cooling tower according to claim 1, wherein the spray line (111) and the bleed line (121) are arranged vertically, and the spray line (111) is arranged vertically and the bleed line (121) is arranged horizontally.

9. A low pressure EGR system comprising the multistage cooling tower (100) of any of claims 1-8.

10. The low-pressure EGR system of claim 9 further comprising a turbocharger (200) and an exhaust gas heat recovery boiler (300), wherein one end of the exhaust gas heat recovery boiler (300) is connected to an exhaust gas outlet of the turbocharger (200), the other end of the exhaust gas heat recovery boiler is connected to a head end of the multistage cooling tower (100), and a tail end of the multistage cooling tower (100) is connected to an air inlet of the turbocharger (200).