CN116857044B

CN116857044B - Marine diesel engine exhaust treatment system

Info

Publication number: CN116857044B
Application number: CN202310765987.5A
Authority: CN
Inventors: 张洋龙; 魏亮; 赵倩; 安思洋
Original assignee: Hudong Heavy Machinery Co Ltd
Current assignee: Hudong Heavy Machinery Co Ltd
Priority date: 2023-06-27
Filing date: 2023-06-27
Publication date: 2024-05-14
Anticipated expiration: 2043-06-27
Also published as: CN116857044A

Abstract

The application relates to the technical field related to ship power and discloses a waste gas treatment system of a marine diesel engine.

Description

Marine diesel engine exhaust treatment system

Technical Field

The application relates to the technical field related to ship power, in particular to a marine diesel engine waste gas treatment system.

Background

With the development of international shipping and ocean-going vessel transportation, exhaust emissions from diesel-fueled marine engines have become a major source of pollution in the ocean (especially in harbour areas). Sulfur oxides and nitrogen oxides in exhaust emissions of marine diesel engines have attracted widespread international social interest in the pollution of the atmospheric environment. TierIII emissions limits are reduced by about 80% based on TierI limits, and currently the relatively mature single technologies that can meet TierIII emissions standards are SCR technology, exhaust Gas Recirculation (EGR) technology, and low pressure injection LNG engines.

SCR technology has a wide application range, and therefore has a small influence on the safety of an engine, and is widely concerned in industry.

An Exhaust Gas Recirculation (EGR) technique is adopted to send a small part of exhaust gas generated by a diesel engine or a gasoline engine back to a cylinder, and the recirculated exhaust gas delays the combustion process due to inertia, so that nitrogen oxide compounds are reduced. While increasing the EGR rate has a positive impact on reducing NOx emissions, it also has a negative impact on the increase in particulate matter and other polluting components.

With low pressure injection LNG engine technology, it is necessary to retrofit the engine and add LNG storage, vaporization and heating devices, while adding a lot of explosion proof equipment. Adding much equipment and cost.

Compared with the current conventional exhaust gas treatment methods of diesel engines, a selective catalytic reduction technology capable of treating exhaust gas is required.

Disclosure of Invention

The application provides a marine diesel engine exhaust gas treatment system which has the advantages of stability, reliability, simple device and low cost, and is used for solving the problems of high cost and low treatment efficiency of diesel engine exhaust gas treatment equipment in the background technology.

In order to achieve the above purpose, the application adopts the following technical scheme: a marine diesel engine exhaust treatment system comprising: the diesel engine is used for propelling the ship, and a large amount of high-temperature waste gas can be discharged after diesel is combusted; an exhaust gas flowmeter arranged on an exhaust gas outlet of the diesel engine for measuring the amount of exhaust gas; the waste gas direct-discharge switch valve is used for bypass of waste gas; a reactor for mixing the exhaust gas and the urea solution; the waste gas treatment switch valve is used for connecting waste gas into the reactor; a urea tank for storing urea; a urea adjusting valve for adjusting a discharge rate of the urea solution according to the set pressure; the urea pump is used for pressurizing and conveying the solution in the urea tank to the urea regulating valve; a standby pump which is cold for standby with the urea pump; the fan unit is used for discharging the waste gas after the reaction; the urea switch valve is used for releasing and blocking urea solution; the urea flowmeter is used for detecting the discharge amount of urea; the purifying process comprises the following steps:

s1, a diesel engine works, and an exhaust gas direct-discharge switching valve is opened;

S2, after delaying for ten seconds, opening a urea switch valve;

S3, waiting for thirty seconds;

S4, after the urea pump, the urea regulating valve and the fan unit are all stable, opening an exhaust gas treatment switching valve and closing an exhaust gas direct-discharge switching valve;

S5, mixing the waste gas and urea in a reactor;

S6, discharging the purified waste gas from the fan unit.

A reactor for mixing urea and exhaust gas in a marine diesel engine exhaust treatment system, the reactor comprising: the buffer cavity is arranged in the reactor; the mixing pipe is fixed in the middle of the reactor and is coaxial with the reactor, a mixing cavity communicated with the buffer cavity is formed in the mixing pipe, the mixing cavity provides conditions for mixing urea and waste gas, and the outer side of the mixing pipe is positioned in the buffer cavity; the urea nozzle is used for atomizing and spraying urea solution into the mixing cavity and is fixedly arranged at the end part of the reactor; a discharge port which is arranged at the end part of the reactor and is used for outputting waste gas; and the exhaust pipe is used for inputting exhaust gas into the buffer cavity and is fixed on the outer side of the reactor.

Furthermore, a flow equalizing head is fixedly arranged on the inner side of the reactor, and the flow equalizing head is in a shape of a circular table.

Further, the reactor is provided with a supporting shaft on the inner side, a dispersing disc is movably sleeved on the outer side of the supporting shaft, dispersing holes are formed in the surface of the dispersing disc, the dispersing disc penetrates through the middle of the mixing tube, the dispersing disc is in sliding connection with the mixing tube, and fan blades are fixedly arranged on the outer side of the dispersing disc.

Further, the dispersing holes in the dispersing plate are arranged in a shape with a narrow middle part and wide two ends.

Further, the lateral wall fixed mounting of hybrid tube has the detecting tube, the inner chamber movable mounting of detecting tube has the detecting head, and detects head end and hybrid chamber intercommunication, the inner chamber movable sleeve of detecting tube has been located the pressure seat of detecting head one side, pressure seat end fixed mounting has the transposition pole, transposition pole and back shaft swing joint, the other end fixed mounting of pressure seat has the return to push the spring, and the one end and the inboard fixed connection of detecting tube of return to push the spring, the sealed cavity of transmission medium oil is equipped with to the inner chamber of detecting tube, the one end of detecting head and the one end of pressure seat, the damping hole that is located the check valve top has been seted up to the inboard of detecting tube.

Further, one end of the pressing seat is provided with an oblique angle, the inner side of the detection tube is movably provided with a locking ball, the top of the locking ball is fixedly connected with a limiting spring positioned on the inner side of the detection tube, and the outer side of the pressing seat is provided with an annular arc groove for clamping the locking ball.

Further, the movable cavity has been seted up to the tip of hybrid tube, and movable mounting has the scraping plate in the movable cavity, the tip and the dispersion impeller sliding connection of scraping plate, the outside of hybrid tube is fixed with the communicating pipe with two movable cavities intercommunication, the communicating infusion chamber with the movable cavity has been seted up to the inboard of hybrid tube, the inboard movable mounting of reactor has the pressure release seat, and the tip of pressure release seat is arranged in the infusion cavity, the transmission oil of sufficient has been put into in movable cavity, communicating pipe and the infusion cavity, the one end fixed mounting of pressure release seat has reset spring.

Further, the end part of the slag scraping plate is provided with an annular sharp angle.

Further, a pressure relief opening is formed in the surface of the pressure relief seat, and a deflation branch channel communicated with the pressure relief opening is formed in the inner side of the reactor.

The invention has the following beneficial effects:

according to the marine diesel engine exhaust gas treatment system provided by the application, the exhaust gas generated by the marine diesel engine enters the reactor through the exhaust gas flowmeter, the urea pump conveys urea to the reactor, the exhaust gas and the urea are mixed in the reactor, the fan unit discharges the gas to the atmosphere, the exhaust gas can effectively reduce NOX emission after passing through the reactor, and finally the aim of reducing nitrogen oxide emission is achieved.

The invention has the advantages of stability, reliability, simple device and low cost, and is suitable for ocean or inland vessels equipped with diesel engines.

Drawings

The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments of the application and together with the description, serve to explain the principles of the application.

The application may be more clearly understood from the following detailed description taken in conjunction with the accompanying drawings, in which:

FIG. 1 is a schematic flow chart of the present invention;

FIG. 2 is a schematic view of the reactor;

FIG. 3 is a perspective view of the interior of the reactor;

FIG. 4 is a schematic diagram showing a sectional view of the inside of the reactor;

FIG. 5 is a schematic diagram of a cross-sectional view of a portion of a reactor;

FIG. 6 is an enlarged schematic view of FIG. 5A;

FIG. 7 is a view showing a structure of a slag scraping plate;

Fig. 8 is a block diagram of the dispersion Kong Poushi in the dispersion disk.

In the figure: 1. a reactor; 100. a discharge port; 101. an exhaust pipe; 102. a buffer cavity; 103. a deflation branch passage; 2. a urea nozzle; 3. a flow equalizing head; 4. a fan blade; 5. a dispersion plate; 6. a support shaft; 8. a mixing tube; 800. a mixing chamber; 801. a movable cavity; 802. an infusion chamber; 9. a detection tube; 900. a damping hole; 901. a one-way valve; 10. a communicating pipe; 11. a slag scraping plate; 12. a pressure relief seat; 120. a pressure relief port; 13. a return spring; 14. a transposition rod; 15. a detection head; 16. a return push spring; 17. a pressing seat; 18. a lock ball; 180. a limit spring; 19. a diesel engine; 20. an exhaust gas flow meter; 21. an exhaust gas direct-discharge switch valve; 22. an exhaust gas treatment switching valve; 23. a urea tank; 24. a urea pump; 240. a backup pump; 25. a urea regulating valve; 26. a urea flowmeter; 27. urea switch valve; 28. a blower unit.

Detailed Description

The following description of the embodiments of the present application will be made clearly and completely with reference to the accompanying drawings, in which it is apparent that the embodiments described are only some embodiments of the present application, but not all embodiments. All other embodiments, which can be made by those skilled in the art based on the embodiments of the application without making any inventive effort, are intended to be within the scope of the application.

Example 1

Referring to fig. 1, a diesel engine 19 is used for propelling a ship, diesel fuel is combusted to discharge a large amount of exhaust gas, an exhaust gas flowmeter 20 is arranged at an exhaust gas outlet of the diesel engine to measure the instantaneous flow of the exhaust gas, an exhaust gas direct-discharge on-off valve 21 is used for bypassing the exhaust gas, an exhaust gas treatment on-off valve 22 is used for introducing the exhaust gas into a reactor 1, a urea tank 23 is used for storing urea, a urea pump 24 can convey the solution in the urea tank 23 into a urea regulating valve 25 under pressure, the urea pump 24 and a standby pump 240 are in cold standby (refer to that the standby system or equipment is in a closed state, is not in an active state, but is in a standby state, and is started or replaced when the main system or equipment fails), the urea regulating valve 25 is regulated according to the pressure set by the system, the urea after pressure stabilization is measured by a urea flowmeter 26 and enters the reactor 1 through a urea on-off valve 27, and a fan unit 28 is used for discharging the reacted exhaust gas.

When in use, the utility model is characterized in that:

When the diesel engine 19 is operated, the exhaust gas in-line switching valve 21 after the exhaust gas flow meter 20 is opened first, the urea switching valve 27 is opened after ten seconds of delay, the exhaust gas treatment switching valve 22 is opened and the exhaust gas in-line switching valve 21 is closed after the urea pump 24, the urea regulating valve 25 and the fan unit 28 are all stationary after thirty seconds of waiting, and then the exhaust gas and urea are fully mixed in the reactor 1 and discharged to the atmosphere through the fan unit 28.

The present embodiment is applicable to an air supply system equipped with a dual fuel engine or a gas engine.

Example two

In the first embodiment, the reactor 1 is mainly used as a tool for mixing urea and exhaust gas, in the prior art, the urea nozzle 2 is placed in the reactor 1, urea solution is dispersed through the urea nozzle 2 and then mixed with high-temperature exhaust gas, so that emission of nitrogen oxides in the exhaust gas is reduced, but in the actual use process, as the urea sprayed by the urea nozzle 2 can generate uneven atomization phenomenon, some large liquid urea can also move along with the air flow, the liquid urea can contact the inner wall of the reactor 1 under self gravity, and as the exhaust gas is continuously mixed with the atomized urea, the subsequent internal temperature of the reactor 1 can be relatively reduced, so that a great amount of crystals are generated in the inner wall of the reactor 1, the crystals can be formed after the crystallization is generated, if the crystals are not cleaned timely, the formation of the crystals can be aggravated, once the crystals are too much, the reactor 1 can be blocked, the exhaust gas can be increased to be pressed, and the performance of the whole machine is deteriorated.

The urea crystallization is that supersaturated urea precipitation crystals are caused by water diversion loss in urea solution, and are products in the physical reaction process, and can be continuously decomposed along with the temperature rise, so that the crystallization is eliminated, but in the actual use process, the temperature rise cannot be ensured in a crystallization area due to the fact that the reactor 1 is a straight-through pipe, so that the crystallization crystals are formed rapidly.

In order to solve the above problems, referring to fig. 2 and 3, a buffer chamber 102 is provided in the reactor 1, meanwhile, a mixing tube 8 is coaxially fixed in the middle of the reactor 1, a mixing chamber 800 communicating with the buffer chamber 102 is provided in the mixing tube 8, the outer side of the mixing tube 8 is located in the buffer chamber 102, as can be seen from fig. 4, a urea nozzle 2 is fixedly installed at the end of the reactor 1, the urea nozzle 2 uniformly sprays urea into the mixing tube 8, a discharge port 100 for outputting waste gas is provided at the other end of the reactor 1, one end of the mixing tube 8 is located in the discharge port 100, an exhaust gas tube 101 for charging high-temperature waste gas into the buffer chamber 102 is fixedly installed at the outer side of the reactor 1, when the waste gas tube 101 inputs the waste gas into the buffer chamber 102, the mixing tube 8 is heated, then, the mixing region is located in the mixing chamber 800 when the waste gas in the buffer chamber 102 is mixed with atomized urea solution sprayed from the urea nozzle 2, and when urea droplets are placed at the inner side of the mixing tube 8, the outer side of the mixing tube 8 is always prevented from being heated by the high-temperature urea crystal in the buffer chamber 102, thereby the inner side 8 is generated.

The inside fixed mounting of reactor 1 has the head 3 that flow equalizes that is located the urea nozzle 2 tip outside, and the shape of head 3 that flow equalizes is round platform form, and the tip of head 3 that flow equalizes is located the one end of hybrid tube 8, because urea nozzle 2 is in the tip of head 3 that flow equalizes, when the air current blows off to urea nozzle 2 from the lateral wall of head 3 that flow equalizes, the air current blows to urea nozzle 2 through the tangential direction in the head 3 outside that flow equalizes, can avoid the liquid emergence drip phenomenon of urea nozzle 2 spun, further assurance waste gas and urea solution mixed homogeneity.

Example III

In order to solve the problem, referring to fig. 4 and 5, a supporting shaft 6 is arranged on the inner side of the reactor 1, a dispersing disc 5 is movably sleeved on the outer side of the supporting shaft 6, dispersing holes for secondarily atomizing urea liquid beads are formed on the surface of the dispersing disc 5, the dispersing disc 5 passes through the middle part of the mixing tube 8, the mixing tube 8 is divided from the middle part, the dispersing disc 5 is in sliding connection with the mixing tube 8, fan blades 4 are fixedly arranged on the outer side of the dispersing disc 5, and the fan blades 4 are blown by the waste gas in the waste gas tube 101 to force the dispersing disc 5 to rotate.

With reference to fig. 8, the dispersing holes in the dispersing disc 5 are arranged in a shape with a narrow middle part and wide two ends, so that when urea droplets move from the narrow middle part of the dispersing disc 5 to a wide end part, the droplets are subjected to secondary dispersing atomization, because: when liquid enters the reducing device from a small diameter, the liquid forms a cavity, i.e., an atomizing cavity, due to the increase in the flow rate of the liquid and the decrease in pressure. When the liquid enters the large diameter, the liquid can be instantaneously broken into small liquid drops due to the limitation of the cavity and the interaction force among liquid molecules to form a vaporific substance, so that the secondary dispersion of uric acid solution is completed.

When the urea spraying device is used, waste gas input in the waste gas pipe 101 can force the fan blades 4 to drive the dispersion disc 5 to rotate, so that the dispersion holes follow the dispersion disc 5 to periodically rotate between the buffer cavity 102 and the mixing cavity 800, urea solution atomized by the urea nozzle 2 firstly enters the inner cavity of the mixing cavity 800 at the left side of the dispersion disc 5, the direction is shown in fig. 4, waste gas and urea in the mixing cavity 800 at the left side are sprayed and mixed, sprayed liquid drops can pass through the dispersion holes on the dispersion disc 5 along with the waste gas, and the urea solution can be secondarily atomized after passing through the dispersion holes, so that the urea liquid drops are not concentrated in the mixing cavity 800.

The urea solution atomized by the urea nozzle 2 and the dispersion disc 5 is in the mixing chamber 800, and thus the external buffer chamber 102 heats the mixing tube 8, so as to achieve the same effect as described in the second embodiment.

The dispersion plate 5 drives the dispersion holes to continuously rotate, so that the dispersion holes after working are placed in the buffer cavity 102, and the dispersion plate 5 is further heated by air flow in the buffer cavity 102, so that the phenomenon of blockage caused by crystallization of urea solution in the dispersion holes is avoided.

Example IV

In the third embodiment, if the dispersion holes on the dispersion disc 5 are plugged and then enter the buffer cavity 102 to eliminate crystallization, but with the rotation of the dispersion disc 5, the dispersion holes still enter the mixing cavity 800 to disperse again, the fourth embodiment aims at prolonging the time that the dispersion holes are in the buffer cavity 102 when the dispersion holes are severely plugged, so as to further eliminate crystallization, please refer to fig. 4-6, the support shaft 6 can move back and forth along the inner side of the reactor 1 and in the radial direction of the mixing tube 8, the side wall of the mixing tube 8 is fixedly provided with the detection tube 9 far away from the flow equalizing head 3, and the gap between the detection tube 9 and the flow equalizing head 3 is blocked by the dispersion disc 5, the inner cavity of the detection tube 9 is movably provided with the detection head 15, the end of the detection head 15 is communicated with the mixing cavity 800, the inner cavity of the detection tube 9 is movably sleeved with the pressing seat 17 positioned at one side of the detection head 15, the end of the pressing seat 17 is fixedly provided with the transposition rod 14, the transposition rod 14 is movably connected with the support shaft 6 through the connecting rod, when the transposition rod 6 moves, the inner side wall of the transposition rod 14 is fixedly provided with the detection spring 901, the inner side of the detection tube 9 is fixedly provided with the pressing seat 17, the inner side of the detection tube is fixedly provided with the detection tube 17, the end of the detection tube is fixedly provided with the detection head 15, the end 17 is fixedly provided with the pressing seat 17, and the end of the detection head 17 is fixedly provided with the mixing cavity 800, and the inner cavity is movably connected with the pressing spring is fixedly provided with the pressing seat 17.

As can be seen from fig. 6, one end of the pressing seat 17 is provided with an oblique angle, the oblique angle is located at one side of the transposition rod 14, the inner side of the detection tube 9 is movably provided with a locking ball 18, the top of the locking ball 18 is fixedly connected with a limiting spring 180 located at the inner side of the detection tube 9, the locking ball 18 is always propped against the outer side of the pressing seat 17 through the limiting spring 180, and an annular arc groove for clamping the locking ball 18 is formed in the outer side of the pressing seat 17, so that when the pressing seat 17 is separated from the locking ball 18, a certain resistance is provided.

When in use, the dispersing holes on the dispersing disc 5 are not blocked, the dispersing disc 5 can work normally according to the third embodiment, and at this time, the pressure input to the end of the detecting head 15 in the mixing cavity 800 combined with the elastic force of the return pushing spring 16 forces the pressing seat 17 to overcome the pressure in the buffer cavity 102, so that the locking balls 18 are clamped in the annular arc grooves.

When the dispersing holes on the dispersing disc 5 are blocked, the air flow pressure input by the mixing cavity 800 to the end part of the detecting head 15 is greatly reduced, when the pressure of the pressing seat 17 is greater than the elastic force of the return pushing spring 16 and the pressure can be separated from the limit of the locking ball 18, the pressure moves towards the direction of the detecting head 15, the medium oil at the end part of the pressing seat 17 is forced to be quickly pushed into the end part of the detecting head 15 through the one-way valve 901, and meanwhile, the dispersing disc 5 synchronously moves towards the mixing tube 8 along with the supporting shaft 6, so that the inner part of the dispersing disc 5 moves into the mixing cavity 800, and the outer side of the dispersing disc 5 is completely arranged in the buffer cavity 102.

When the dispersing holes at the inner side of the dispersing disc 5 are pushed into the mixing cavity 800, the pressure applied to the end part of the detecting head 15 is increased, the pressure applying seat 17 is forced to move away from the one-way valve 901 under the action of the pressure increase at the end part of the detecting head 15 and the elasticity of the return pushing spring 16, and the medium oil at the end part of the detecting head 15 can only slowly flow out of the damping hole 900, so that the pressure applying seat 17 can slowly reset, and meanwhile, when the pressure applying seat 17 drives the supporting shaft 6 to slowly reset, the time that the outer side area of the dispersing disc 5 stays in the buffer cavity 102 is prolonged, so that the heating time of the dispersing holes at the outer side of the dispersing disc 5 is prolonged, and uric acid crystallization is further eliminated.

Example five

On the basis of the fourth embodiment, because when the inner side area of the dispersion disc 5 moves into the mixing cavity 800, if the surface of the dispersion disc 5 is crystallized, the crystallization part can prevent the dispersion disc 5 from running, so that the outer side of the dispersion disc 5 is not easy to separate from the mixing tube 8, and meanwhile, the rotation of the dispersion disc 5 is not easy to be facilitated, in order to prevent the occurrence of such problems, referring to fig. 4-7, the end part of the mixing tube 8 is provided with a movable cavity 801, in the movable cavity 801, a slag scraping plate 11 is movably arranged, the end part of the slag scraping plate 11 is slidably connected with the dispersion disc 5, the end part of the slag scraping plate 11 is provided with annular sharp corners, and because two opposite surfaces of the dispersion disc 5 are easy to produce crystals, the number of the slag scraping plate 11 is two, the number of the movable cavity 801 is two as well, the outer side of the mixing tube 8 is provided with a communicating tube 10 which is communicated with the two movable cavities 801, in combination with fig. 4, the inner side of the mixing tube 8 is provided with an infusion cavity 802, the inner side of the reactor 1 is movably provided with a pressure release seat 12, and the end part of the pressure release seat 12 is movably arranged in the infusion cavity 802, and the end part of the pressure release seat 12 is positioned in the infusion cavity 802, and the pressure release seat 11 is movably arranged, and is positioned in the infusion cavity 11, and is directly pressed by the pressure release seat 11 and is directly pressed by the pressure release seat 13, and the pressure release seat is pressed by the pressure release plate 11, and the pressure release seat is directly has a spring, and is pressed by the pressure release plate 11, and is pressed by the pressure release plate 13, and the pressure release seat is directly has the pressure release plate and is released from the pressure release seat 13.

The surface of the pressure release seat 12 is provided with a pressure release opening 120, and the inner side of the reactor 1 is provided with a gas release branch 103 communicated with the pressure release opening 120, so that after the pressure release seat 12 compresses the return spring 13, the gas release branch 103 is forced to be communicated with the mixing cavity 800 through the pressure release opening 120, and finally, the waste gas is discharged into the discharge opening 100 through the gas release branch 103.

Inside the end of the mixing tube 8 and in the discharge opening 100 there is a protruding ring protruding inwards, so that it is ensured that the exhaust gases in the mixing chamber 800 can build up a certain pressure.

When in use, the pressure release seat 12 is extruded by the elastic force of the return spring 13, so that the transmission oil pressure in the transfusion cavity 802 is increased, the slag scraping plate 11 is forced to be clung to the dispersion plate 5, and after crystallization occurs on the surface of the dispersion plate 5, the slag is scraped by the slag scraping plate 11.

If the crystals are smaller and not completely scraped once, the crystals can push the scraping plate 11 to move in a direction away from the dispersion disc 5, so that along with the rotation of the dispersion disc 5, the outermost side of the crystals is scraped by the scraping plate 11, and at the moment, the scraping plate 11 moves and does not communicate the pressure relief opening 120 with the mixing cavity 800, and along with the continuous scraping of the scraping plate 11, the outer side of the crystals on the dispersion disc 5 is scraped, so that the crystals are scraped.

If the crystals are larger, the movement stroke of the scraping plate 11 is increased, so that the pressure relief opening 120 is communicated with the mixing cavity 800, the mixing cavity 800 is forced to further input waste gas into the discharge opening 100 through the pressure relief opening 120 and the air release branch 103, so that the waste gas in the mixing cavity 800 is rapidly reduced, in combination with the fourth embodiment, the pressure in the mixing cavity 800 is reduced, the inner area of the dispersion plate 5 is input into the mixing cavity 800 to work, when the outer side of the dispersion plate 5 moves into the buffer cavity 102, the heating time is increased, and as the outer side of the dispersion plate 5 moves continuously into the mixing cavity 800, the scraping plate 11 can scrape crystals continuously, at this time, the heated crystals are more easily scraped, and the crystals on the surface of the dispersion plate 5 are completely scraped.

If the movable range of the scraper 11 located at the side of the detection tube 9 is increased due to crystals, the air flow in the buffer chamber 102 partially flows into the mixing chamber 800, but the leakage flow strength in the pressure release port 120 is high, and the pressure in the mixing chamber 800 is reduced, so that the above-mentioned problems are achieved.

Claims

1. A marine diesel engine exhaust treatment system, comprising:

a diesel engine (19) for propelling the ship, which emits a large amount of high-temperature exhaust gas after combusting diesel;

An exhaust gas flow meter (20) installed at an exhaust gas outlet of the diesel engine (19) for metering the amount of exhaust gas;

an exhaust gas in-line switching valve (21) for bypass of exhaust gas;

A reactor (1) for mixing the exhaust gases with the urea solution;

an exhaust gas treatment switching valve (22) for switching exhaust gas into the reactor (1);

a urea tank (23) for storing urea;

a urea adjustment valve (25) for adjusting the discharge rate of the urea solution according to the set pressure;

a urea pump (24) for pressurizing and delivering the solution in the urea tank (23) to a urea regulating valve (25);

A standby pump (240) which is cold standby with the urea pump (24);

a fan unit (28) for discharging the reacted exhaust gas;

a urea switch valve (27) for releasing and blocking the urea solution;

A urea flowmeter (26) for detecting the amount of urea discharged;

the purifying process comprises the following steps:

S1, a diesel engine (19) works, and an exhaust gas straight-line switch valve (21) is opened;

S2, after delaying for ten seconds, opening a urea switch valve (27);

S3, waiting for thirty seconds;

s4, after the urea pump (24), the urea regulating valve (25) and the fan unit (28) are all stable, opening the waste gas treatment switching valve (22) and closing the waste gas direct-discharge switching valve (21);

S5, mixing the waste gas and urea in a reactor (1);

s6, discharging purified waste gas from a fan unit (28);

the reactor (1) comprises:

the buffer cavity (102) is arranged in the reactor (1);

The mixing pipe (8) is fixed in the middle of the reactor (1) and is coaxial with the reactor (1), a mixing cavity (800) communicated with the buffer cavity (102) is formed in the mixing pipe (8), the mixing cavity (800) provides conditions for mixing urea and waste gas, and the outer side of the mixing pipe (8) is positioned in the buffer cavity (102);

the urea nozzle (2) is used for atomizing and spraying urea solution into the mixing cavity (800) and is fixedly arranged at the end part of the reactor (1);

a discharge port (100) which is formed at the end of the reactor (1) and is used for outputting waste gas;

An exhaust pipe (101) for inputting exhaust gas into the buffer cavity (102), the exhaust pipe (101) being fixed at the outside of the reactor (1);

The reactor is characterized in that a supporting shaft (6) is arranged on the inner side of the reactor (1), a dispersing disc (5) is movably sleeved on the outer side of the supporting shaft (6), dispersing holes are formed in the surface of the dispersing disc (5), the dispersing disc (5) penetrates through the middle of the mixing tube (8), the dispersing disc (5) is in sliding connection with the mixing tube (8), and fan blades (4) are fixedly arranged on the outer side of the dispersing disc (5).

2. The marine diesel engine exhaust gas treatment system according to claim 1, wherein a flow equalization head (3) is fixedly installed on the inner side of the reactor (1), and the flow equalization head (3) is in a truncated cone shape.

3. A marine diesel engine exhaust gas treatment system according to claim 1, characterized in that the dispersion holes in the dispersion plate (5) are arranged in a shape with a narrow middle and wide ends.

4. The marine diesel engine exhaust gas treatment system according to claim 1, wherein the side wall of the mixing pipe (8) is fixedly provided with a detection pipe (9), the inner cavity of the detection pipe (9) is movably provided with a detection head (15), the end part of the detection head (15) is communicated with the mixing cavity (800), the inner cavity of the detection pipe (9) is movably sleeved with a pressing seat (17) positioned at one side of the detection head (15), the end part of the pressing seat (17) is fixedly provided with a transposition rod (14), the transposition rod (14) is movably connected with the supporting shaft (6), the other end of the pressing seat (17) is fixedly provided with a return pushing spring (16), one end of the return pushing spring (16) is fixedly connected with the inner side of the detection pipe (9), the inner cavity of the detection pipe (9), one end of the detection head (15) and one end of the pressing seat (17) form a sealing cavity filled with transmission medium oil, and the inner side of the detection pipe (9) is provided with a damping hole (900) positioned above the one-way valve (901).

5. The marine diesel engine exhaust gas treatment system according to claim 4, wherein an oblique angle is arranged at one end of the pressing seat (17), a locking ball (18) is movably mounted at the inner side of the detection tube (9), a limit spring (180) positioned at the inner side of the detection tube (9) is fixedly connected to the top of the locking ball (18), and an annular arc groove for clamping the locking ball (18) is formed at the outer side of the pressing seat (17).

6. The marine diesel engine exhaust gas treatment system according to claim 4, wherein the end portion of the mixing pipe (8) is provided with a movable cavity (801), a slag scraping plate (11) is movably installed in the movable cavity (801), the end portion of the slag scraping plate (11) is slidably connected with the dispersion disc (5), a communicating pipe (10) for communicating the two movable cavities (801) is fixed on the outer side of the mixing pipe (8), an infusion cavity (802) communicated with the movable cavity (801) is formed in the inner side of the mixing pipe (8), a pressure relief seat (12) is movably installed in the inner side of the reactor (1), the end portion of the pressure relief seat (12) is located in the infusion cavity (802), a sufficient amount of transmission oil is placed in the movable cavity (801), the communicating pipe (10) and the infusion cavity (802), and a reset spring (13) is fixedly installed at one end of the pressure relief seat (12).

7. A marine diesel engine exhaust gas treatment system according to claim 6, characterized in that the end of the scraper (11) is provided with a ring-shaped sharp corner.

8. The marine diesel engine exhaust gas treatment system according to claim 6, wherein the surface of the pressure relief seat (12) is provided with a pressure relief opening (120), and the inner side of the reactor (1) is provided with a gas release branch (103) communicated with the pressure relief opening (120).