阅读说明：本技术 一种新型柴油机尾气低压选择性催化还原脱硝系统 (Novel diesel engine tail gas low pressure selective catalytic reduction denitration system ) 是由 郭江峰 杨新伟 于 2021-08-09 设计创作，主要内容包括：本发明公开了一种船用柴油机尾气处理系统,包括脱硝反应单元、旁通单元、还原剂供给单元以及还原剂计量喷射单元,旁通单元用于控制脱硝反应单元的接入反应量；还原剂计量喷射单元集成设置在柴油机的排气集管上,且还原剂计量喷射单元的多个喷嘴轴向间隔渐变或等间隔的布置在排气集管上；还原剂计量喷射单元在控制器的控制下将还原剂供给单元提供的还原剂流量和压力可调的向排气集管计量喷射；脱硝反应单元设置在增压器的上游或下游并与来自排气集管的还原剂反应处理尾气,增压器的增压轮侧与进气管和柴油机的扫气集管连接提供增压气体。本系统具有净化效率高、结构紧凑、占地面积小、成本低等优点。(The invention discloses a tail gas treatment system of a marine diesel engine, which comprises a denitration reaction unit, a bypass unit, a reducing agent supply unit and a reducing agent metering and spraying unit, wherein the bypass unit is used for controlling the access reaction amount of the denitration reaction unit; the reducing agent metering and injecting unit is integrally arranged on an exhaust manifold of the diesel engine, and a plurality of nozzles of the reducing agent metering and injecting unit are arranged on the exhaust manifold in a gradual change or equal interval mode in the axial direction; the reducing agent metering and injecting unit is used for metering and injecting the reducing agent provided by the reducing agent supply unit to the exhaust manifold in an adjustable flow and pressure manner under the control of the controller; the denitration reaction unit is arranged at the upstream or the downstream of the supercharger and reacts with the reducing agent from the exhaust manifold to treat the tail gas, and the side of the supercharger, which is connected with the air inlet pipe and the scavenging manifold of the diesel engine, provides the supercharging gas. The system has the advantages of high purification efficiency, compact structure, small occupied area, low cost and the like.)

1. The utility model provides a marine diesel engine exhaust gas treatment system, processing system (100) include denitration reaction unit (10), bypass unit (20), reductant supply unit (30) and reductant measurement injection unit (40), its characterized in that: the bypass unit (20) is used for controlling the access reaction amount of the denitration reaction unit (10); the reducing agent metering and injecting unit (40) is integrally arranged on an exhaust manifold (400) of the diesel engine (300), and a plurality of nozzles of the reducing agent metering and injecting unit (40) are arranged on the exhaust manifold (400) in a gradual or equal interval mode in the axial direction; the reducing agent supply unit (30) supplies reducing agent to the reducing agent metering injection unit (40) in an adjustable concentration under the control of the controller (600), and the reducing agent metering injection unit (40) meters and injects the reducing agent provided by the reducing agent supply unit (30) to the exhaust manifold (400) in an adjustable flow and pressure under the control of the controller (600); the denitration reaction unit (10) is arranged at the upstream or the downstream of the supercharger (200) and reacts with a reducing agent from an exhaust manifold (400) to treat exhaust gas, and the supercharger side of the supercharger (200) is connected with an air inlet pipe and a scavenging manifold (500) of the diesel engine (300) to provide supercharged gas.

2. The marine diesel engine exhaust treatment system of claim 1, wherein: the reducing agent supply unit (30) comprises a reducing agent tank (31) and a reducing agent pump (32), the reducing agent metering injection unit (40) comprises a metering device (41) and an injection valve (42), the reducing agent tank (31), the reducing agent pump (32), the metering device (41) and the injection valve (42) are sequentially connected, and the tail end of the injection valve (42) is connected with a plurality of nozzles to non-uniformly inject the reducing agent to the exhaust manifold (400).

3. The marine diesel exhaust treatment system of claim 2, wherein: the reducing agent in the reducing agent tank (31) is one or a combination of a urea solution and ammonia water.

4. The marine diesel exhaust treatment system of claim 2 or 3, wherein: the denitration reaction unit (10) comprises a denitration reactor (11), an air inlet valve (12) and an air outlet valve (13), wherein the air inlet valve (12), the denitration reactor (11) and the air outlet valve (13) are sequentially arranged on an exhaust pipe (14) at the downstream of the supercharger (200) or the exhaust header (400).

5. The marine diesel engine exhaust treatment system of claim 4, wherein: when the denitration reaction unit (10) is connected to a supercharging exhaust branch pipe (14) of the supercharger (200), the bypass unit (20) comprises a bypass valve (21) and a bypass pipe (22), the bypass pipe (22) is arranged in a bypass parallel mode between the upstream of the air inlet valve (12) and the downstream of the denitration reactor (11), the bypass valve (21) is arranged on the bypass pipe (22), and the access of the bypass valve (21) is controlled through a controller (600).

6. The marine diesel engine exhaust treatment system of claim 4, wherein: when the denitration reaction unit (10) is connected to the inline branch pipe (15) downstream of the exhaust header (400), the bypass unit (20) includes a bypass valve (21) and a bypass pipe (22), both ends of the bypass pipe (22) are connected in parallel with both ends of the turbine of the supercharger (200), and the bypass valve (21) is provided on the bypass pipe (22); a supercharging exhaust valve (16) is arranged on a supercharging exhaust branch pipe (14) between an exhaust manifold (400) and a turbine of a supercharger (200), and the tail end of a pipeline of the denitration reaction unit (10) is connected to a pipeline between the supercharging exhaust valve (16) and a bypass pipe (22); the outlet valve (13) is controllably connected with the scavenging manifold (500) through a reaction direct-discharge valve (23) and a pipeline; the controller (600) is used for controlling the access and the opening degree of the bypass valve (21), the air inlet valve (12), the air outlet valve (13), the pressurization exhaust valve (16) and the reaction direct exhaust valve (23).

7. The marine diesel engine exhaust treatment system of claim 4, wherein: when the plurality of nozzles of the reducing agent metering and injecting unit (40) are arranged on the exhaust manifold (400) in a gradual change mode in axial intervals, the intervals between the plurality of nozzles at the tail end of the reducing agent metering and injecting unit (40) become larger from the upstream to the downstream of the exhaust manifold (400).

8. The marine diesel engine exhaust treatment system of claim 1, wherein: the system (100) is suitable for marine low-speed, medium-speed and high-speed diesel engine hosts and diesel engine generator sets, and the power of the diesel engine covers 200 kW-80000 kW.

9. The marine diesel engine exhaust treatment system of claim 1, wherein: the marine diesel engine is suitable for oil products including but not limited to light oil, marine fuel oil or heavy oil.

Technical Field

The invention relates to a ship engine tail gas treatment technology, in particular to a novel diesel engine tail gas low-pressure selective catalytic reduction denitration system.

Background

Nitrogen oxides (NOx) in marine diesel exhaust are one of the important constituents of atmospheric pollutants and have a more direct hazard to the health of both humans and animals. With the initial implementation of the IMO Tier III regulations and the expanding Emissions Control Area (ECA), there is an increasing need to research and develop environmentally friendly processes suitable for the purification of ship exhaust. Selective Catalytic Reduction (SCR) for removing NOx is one of widely accepted methods for effectively removing NOx at present, and plays a key role in industries such as thermal power generation, automobiles, ships and the like in recent years.

In the field of ships, a high-low pressure (corresponding to a reaction system connected to a supercharger in front and back) SCR system has the characteristics of small diesel engine change, simple system arrangement and the like, and is widely considered as one of marine SCR with the most wide application prospect in the future. However, after the diesel engine exhaust gas is subjected to work by the supercharger, the exhaust temperature of the exhaust gas is obviously reduced (220 ℃ and 280 ℃), which brings great challenges to the SCR system to exert denitration performance. The difficulty is mainly that the reducing agent can not be decomposed sufficiently, for example, the urea solution usually needs more than 280 ℃ to be decomposed thermally to generate ammonia (NH3) required by the reaction, and when the tail gas temperature is not enough to support the sufficient thermal decomposition, a large amount of crystal substances are generated at the inlet of the reactor, so that the SCR system loses the purification performance. In order to solve this problem, various methods have been developed by marine diesel engine manufacturers such as shann, doushan, and modern times internationally, for example, korea has developed a method of heating exhaust gas by using an afterburner to promote thermal decomposition of urea (CN 107667210A); korean modern development has conducted a method of drawing part of high temperature exhaust gas from the front of the supercharger to promote thermal decomposition of urea (CN 107787397B). However, these methods have significant disadvantages, such as additional energy consumption caused by the heating by the afterburner, complex system and high cost; the method of utilizing high-temperature exhaust gas before the supercharger to guide flow can cause the control difficulty of the SCR system to be increased, and the urea decomposition effect is not obvious.

In addition, the SCR reactor is installed at the front end of the supercharger of the marine diesel engine, because the exhaust gas at the front end of the supercharger does not work, the temperature of the SCR reactor is usually high (280-. However, the disadvantage is also obvious, and a long reductant evaporation mixing tube is usually arranged in front of the reactor in the system to ensure that the reductant is fully decomposed and fully mixed with the flue gas, so that a good purification effect can be obtained when the reductant passes through the reactor. However, this brings certain difficulties to the system layout, which results in a large overall occupied area of the system and high system cost.

Disclosure of Invention

In order to overcome the defects of the prior art, the invention aims to provide a marine diesel engine tail gas treatment system, which can solve the problems.

The design principle is as follows: the scheme combines the structure of the marine diesel engine and the exhaust emission characteristic, integrates the reducing agent injection unit on the front exhaust collecting pipe of the supercharger of the diesel engine, and can fully utilize the waste heat of the tail gas of the diesel engine for thermal decomposition of the reducing agent and simultaneously realize the full mixing of the reducing agent and the exhaust gas of the diesel engine due to the higher temperature (280-500 ℃) of the exhaust collecting pipe.

The purpose of the invention is realized by adopting the following technical scheme.

A marine diesel engine tail gas treatment system comprises a denitration reaction unit, a bypass unit, a reducing agent supply unit and a reducing agent metering and spraying unit, wherein the bypass unit is used for controlling the access reaction amount of the denitration reaction unit; the reducing agent metering and injecting unit is integrally arranged on an exhaust manifold of the diesel engine, and a plurality of nozzles of the reducing agent metering and injecting unit are arranged on the exhaust manifold in a gradual change or equal interval mode in the axial direction; the reducing agent supply unit is used for supplying reducing agent to the reducing agent metering injection unit in an adjustable concentration manner under the control of the controller, and the reducing agent metering injection unit is used for metering and injecting the reducing agent provided by the reducing agent supply unit into the exhaust manifold in an adjustable flow and pressure manner under the control of the controller; the denitration reaction unit is arranged at the upstream or the downstream of the supercharger and reacts with the reducing agent from the exhaust manifold to treat the tail gas, and the side of the supercharger, which is connected with the air inlet pipe and the scavenging manifold of the diesel engine, provides the supercharging gas.

Preferably, the reducing agent supply unit comprises a reducing agent tank and a reducing agent pump, the reducing agent metering and injecting unit comprises a meter and an injection valve, the reducing agent tank, the reducing agent pump, the meter and the injection valve are sequentially connected, and the tail end of the injection valve is connected with a plurality of nozzles to unevenly inject the reducing agent to the exhaust manifold.

Preferably, the reducing agent in the reducing agent tank is one or a combination of a urea solution and ammonia water.

Preferably, the denitration reaction unit includes a denitration reactor, an air inlet valve and an air outlet valve, and the air inlet valve, the denitration reactor and the air outlet valve are sequentially disposed on an exhaust pipe downstream from the supercharger or the exhaust manifold.

Preferably, when the denitration reaction unit is connected to a supercharging exhaust branch pipe of the supercharger, the bypass unit comprises a bypass valve and a bypass pipe, the bypass pipe bypasses and is arranged in parallel between the upstream of the air inlet valve and the downstream of the denitration reactor, the bypass valve is arranged on the bypass pipe, and the controller controls the connection of the bypass valve.

Preferably, when the denitration reaction unit is connected to the inline manifolds downstream of the exhaust header, the bypass unit includes a bypass valve and a bypass pipe, both ends of the bypass pipe are connected in parallel with both ends of the turbine of the supercharger, and the bypass valve is provided on the bypass pipe; a supercharging exhaust valve is arranged on a supercharging exhaust branch pipe between an exhaust header and a supercharger turbine, and the tail end of a pipeline of the denitration reaction unit is connected to a pipeline between the supercharging exhaust valve and a bypass pipe; the gas outlet valve is controllably connected with the scavenging manifold through a reaction direct discharge valve and a pipeline; the controller controls the access and opening of the bypass valve, the air inlet valve, the air outlet valve, the pressurization exhaust valve and the reaction direct exhaust valve.

Preferably, the plurality of nozzles at the end of the reducing agent meter injection unit are sequentially enlarged in interval from upstream to downstream of the exhaust manifold.

Preferably, the system is suitable for marine low-speed, medium-speed and high-speed diesel engine hosts and diesel engine generator sets, and the power of the diesel engine covers 200 kW-80000 kW.

Preferably, the marine diesel engine-suitable oil includes, but is not limited to, light oil, marine fuel oil, or heavy oil.

Compared with the prior art, the invention has the beneficial effects that: the system has the advantages of high purification efficiency, compact structure, small occupied area, low cost and the like.

Drawings

FIG. 1 is a schematic diagram of one embodiment of a marine diesel exhaust treatment system;

fig. 2 is a schematic diagram of a second embodiment of a marine diesel exhaust treatment system.

Detailed Description

In order to make the objects, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are some, but not all, embodiments of the present invention. All other embodiments, which can be obtained by a person skilled in the art without any inventive step based on the embodiments of the present invention, are within the scope of the present invention.

The marine engine exhaust gas intake schematic, see fig. 1 and 2, includes a diesel engine 300, an exhaust manifold 400, a supercharger 200, a scavenging manifold 500, and an exhaust gas treatment system 100.

The marine diesel exhaust gas treatment system 100 includes a denitration reaction unit 10, a bypass unit 20, a reducing agent supply unit 30, and a reducing agent metering and injecting unit 40.

Wherein, the bypass unit 20 is used for controlling the access reaction amount of the denitration reaction unit 10; the reducing agent metering and injecting unit 40 is integrally arranged on an exhaust manifold 400 of the diesel engine 300, and a plurality of nozzles of the reducing agent metering and injecting unit 40 are arranged on the exhaust manifold 400 in a gradual change mode at axial intervals; the reducing agent supply unit 30 can supply reducing agent to the reducing agent metering and injecting unit 40 in an adjustable concentration under the control of the controller 600, and the reducing agent metering and injecting unit 40 can meter and inject the reducing agent provided by the reducing agent supply unit 30 to the exhaust manifold 400 in an adjustable flow and pressure under the control of the controller 600; the denitration reaction unit 10 is disposed upstream or downstream of the supercharger 200 and reacts with the reducing agent from the exhaust manifold 400 to treat the exhaust gas, and the supercharger 200 is connected on the supercharger side to the intake pipe and the scavenging manifold 500 of the diesel engine 300 to supply the supercharged gas.

The reducing agent supply unit 30 comprises a reducing agent tank 31 and a reducing agent pump 32, the reducing agent metering and injecting unit 40 comprises a metering device 41 and an injection valve 42, the reducing agent tank 31, the reducing agent pump 32, the metering device 41 and the injection valve 42 are sequentially connected, and the tail end of the injection valve 42 is connected with a plurality of nozzles to unevenly inject the reducing agent to the exhaust manifold 400.

The reducing agent in the reducing agent tank 31 is one or a combination of a urea solution and ammonia water.

The denitration reaction unit 10 includes a denitration reactor 11, an intake valve 12, and an exhaust valve 13, and the intake valve 12, the denitration reactor 11, and the exhaust valve 13 are provided in this order on an exhaust pipe 14 downstream from the supercharger 200 or the exhaust manifold 400.

The plurality of nozzles at the end of the reductant metering and injecting unit 40 are sequentially spaced larger from the upstream to the downstream of the exhaust manifold 400 according to the thermodynamic calculation according to the temperature arrangement at the exhaust manifold 400, so that the temperature of the exhaust mixture of the reductant supplied and discharged at the final end is uniform.

The system 100 is suitable for marine low-speed, medium-speed and high-speed diesel engine hosts and diesel engine generator sets, and the power of the diesel engine covers 200 kW-80000 kW.

The marine diesel engine is suitable for oil products including, but not limited to, light oil (MGO), marine fuel oil (MDO), or heavy oil (HFO).

It should be noted that: the concentration of the reducing agent can be adjusted by a reducing agent tank 31, for example, a reducing agent tank is connected in parallel with a hot water tank (temperature control is performed by an engine circulating water circuit) to form the reducing agent tank 31, and a corresponding pump and a flow control valve are arranged at the downstream of each tank, so that the concentration of the supplied reducing agent can be adjusted.

Further, urea or ammonia water as a reducing agent may be supplied together and connected in parallel, and the controller 600 selects whether to connect or not according to the environment.

② the flow adjustment of the reducing agent is controlled by the meter 41, the injection valve 42 and the reducing agent pump 32.

Example one

The denitration reaction unit 10 is connected to the supercharging exhaust branch pipe 14 of the supercharger 200, the bypass unit 20 includes a bypass valve 21 and a bypass pipe 22, the bypass pipe 22 is arranged in parallel by bypassing between the upstream of the intake valve 12 and the downstream of the denitration reactor 11, the bypass valve 21 is arranged on the bypass pipe 22, and the controller 600 controls the connection of the bypass valve 21.

The working principle is as follows: the injection valve 42 of the reducing agent metering and injecting unit 40 in the SCR system is integrated on the exhaust manifold 400 before the diesel engine is supercharged; after the denitration reactor 11 is arranged on the diesel engine supercharger 200, the operation pressure of the denitration reactor 1 is approximate to normal pressure; after the diesel engine starts the Tier III operation mode, the SCR system starts to operate, and the reducing agent is directly sprayed into the diesel engine exhaust header 400; because the exhaust manifold 400 collects the exhaust gas after the fuel in the cylinder is fully combusted, the temperature of the exhaust gas is higher (280-500 ℃), the injected reducing agent urea, ammonia water or the combination of the urea and the ammonia water is fully thermally decomposed under the action of the high-temperature flue gas, and NH required by SCR reaction is generated₃(ii) a Generated NH₃Fully mixed with the high-temperature flue gas, acted by a supercharger 200, and then enters a denitration reactor 11, and NH is carried out under the action of a catalyst₃Reacts with NOx in the waste gas through selective catalytic reduction to generate N₂And H₂And O, thereby achieving the aim of purifying the exhaust gas of the diesel engine. The embodiment is suitable for a low-pressure selective catalytic reduction denitration system.

Experimental verification example 1

The system is installed on a 6S50-MEC 8.5 marine low-speed diesel engine (rated power 9960KW, rotating speed 127rpm), and the fuel oil is low-sulfur oil (MGO). At 75% load on the diesel engine, the new LP-SCR system starts to operate after switching to Tier III mode of operation. The reducing agent supply unit conveys the 40. wt% urea solution to the reducing agent injection unit, and the urea solution is directly injected into an exhaust manifold of the diesel engine, and enters the SCR reactor to carry out denitration reaction after acting by the supercharger. When the ammonia nitrogen ratio is 0.85, the detection shows that the concentration of NOx in the purified diesel engine exhaust gas is 203ppm, and the ammonia escape is 1 ppm.

Experimental validation example 2

The system is installed on a 6S50-MEC 8.5 marine low-speed diesel engine (rated power 9960KW, rotating speed 127rpm), and the fuel oil is low-sulfur oil (MGO). When the diesel engine is at 100% load, the novel LP-SCR system starts to operate after the diesel engine is switched to a Tier III operation mode. The reducing agent supply unit conveys the 40. wt% urea solution to the reducing agent injection unit, and the urea solution is directly injected into an exhaust manifold of the diesel engine, and enters the SCR reactor to carry out denitration reaction after acting by the supercharger. When the ammonia nitrogen ratio is 0.95, the detection shows that the concentration of NOx in the purified diesel engine exhaust gas is 189ppm, and the ammonia escape is 2 ppm.

Experimental validation example 3

The system is installed on a MAN 6L23-30H marine auxiliary engine (rated power 852KW, rotating speed 720rpm), and the fuel oil is low sulfur oil (MGO). At 75% load, the diesel engine is switched to Tier III mode of operation and the new LP-SCR system begins to operate. The reducing agent supply unit conveys the 40. wt% urea solution to the reducing agent injection unit, and the urea solution is directly injected into an exhaust manifold of the diesel engine, and enters the SCR reactor to carry out denitration reaction after acting by the supercharger. When the ammonia nitrogen ratio is 0.85, the detection shows that the concentration of NOx in the purified diesel engine exhaust gas is 157ppm, and the ammonia escape is 2 ppm.

Experimental validation example 4

The system is installed on a MAN 6L23-30H marine medium-speed auxiliary engine diesel engine (rated power 852KW, rotating speed 720rpm), and the fuel oil is low-sulfur oil (MGO). When the diesel engine is at 100% load, the diesel engine is switched to a Tier III operation mode, and the novel LP-SCR system starts to operate. The reducing agent supply unit conveys the 40. wt% urea solution to the reducing agent injection unit, and the urea solution is directly injected into an exhaust manifold of the diesel engine, and enters the SCR reactor to carry out denitration reaction after acting by the supercharger. When the ammonia nitrogen ratio is 0.95, the detection shows that the concentration of NOx in the purified diesel engine exhaust gas is 174ppm, and the ammonia escape is 1 ppm.

Experimental validation example 5

The system is installed on a 6S50-MEC 8.5 marine low-speed diesel engine (rated power 9960KW, rotating speed 127rpm), and the fuel oil is Marine Diesel Oil (MDO). At 75% load on the diesel engine, the new LP-SCR system starts to operate after switching to Tier III mode of operation. The reducing agent supply unit conveys the 40. wt% urea solution to the reducing agent injection unit, and the urea solution is directly injected into an exhaust manifold of the diesel engine, and enters the SCR reactor to carry out denitration reaction after acting by the supercharger. When the ammonia nitrogen ratio is 0.85, the detection shows that the concentration of NOx in the purified diesel engine exhaust gas is 224ppm, and the ammonia escape is 1 ppm.

Experimental verification example 6

The system is installed on a 6S50-MEC 8.5 marine low-speed diesel engine (rated power 9960KW, rotating speed 127rpm), and the fuel oil is low-sulfur oil (MDO). At 75% load on the diesel engine, the new LP-SCR system starts to operate after switching to Tier III mode of operation. The reducing agent supply unit conveys 20 wt.% of ammonia water to the reducing agent injection unit, the ammonia water is directly injected into an exhaust manifold of the diesel engine, and the ammonia water enters the SCR reactor to carry out denitration reaction after acting by the supercharger. When the ammonia nitrogen ratio is 0.85, the detection shows that the concentration of NOx in the purified diesel engine exhaust gas is 205ppm, and the ammonia escape is 1 ppm.

Example two

The reaction unit 10 is connected to the in-line branch pipes 15 downstream of the exhaust header 400, the bypass unit 20 includes a bypass valve 21 and a bypass pipe 22, both ends of the bypass pipe 22 are connected in parallel with both ends of the turbine of the supercharger 200, and the bypass valve 21 is provided on the bypass pipe 22; a booster exhaust valve 16 is arranged on a booster exhaust branch pipe 14 between an exhaust manifold 400 and a turbine of the supercharger 200, and the tail end of a pipeline of the denitration reaction unit 10 is connected to a pipeline between the booster exhaust valve 16 and a bypass pipe 22; the outlet valve 13 is controllably connected with the scavenging manifold 500 through a reaction direct vent valve 23 and a pipeline; the controller 600 controls the access and opening of the bypass valve 21, the intake valve 12, the exhaust valve 13, the booster exhaust valve 16 and the reactive direct discharge valve 23.

The working principle is as follows: the embodiment is suitable for a high-pressure selective catalytic reduction denitration system (HP-SCR) device for purifying nitrogen oxides in tail gas of marine diesel engineAccording to the method, a reducing agent injection valve in an SCR system is integrated on an exhaust manifold before the diesel engine is supercharged. After the diesel engine starts the Tier III operation mode, the SCR system starts to operate, and a reducing agent is directly injected into the diesel engine exhaust header 400 through a nozzle of an injection valve; in the exhaust manifold, because the exhaust gas temperature is higher (280-500 ℃), the injected reducing agent is subjected to sufficient thermal decomposition to generate NH required by SCR reaction₃Fully mixed with the high-temperature flue gas, and then enters a denitration reactor to carry out selective catalytic reduction reaction to generate N₂And H₂O, thereby achieving the purpose of purifying the exhaust gas of the diesel engine; the purified waste gas directly enters the supercharger to continuously push the supercharger to do work. The novel HP-SCR system has the characteristics of high purification efficiency, small occupied area and the like, and simultaneously, the performance of the supercharger and the performance of the diesel engine cannot be influenced. Specific experimental verification examples are as follows.

Experimental validation example 7

The system is installed on a 6S50-MEC 8.5 marine low-speed diesel engine (rated power 9960KW, rotating speed 127rpm), and the fuel oil is low-sulfur oil (MGO). At 75% load on the diesel engine, the new HP-SCR system starts to operate after switching to Tier III mode of operation. The reducing agent supply unit conveys the 40 wt% urea solution to the reducing agent injection unit, and the urea solution is directly injected into an exhaust manifold of the diesel engine and then enters the SCR reactor along with the exhaust gas to carry out denitration reaction. When the ammonia nitrogen ratio is 0.85, the detection shows that the concentration of NOx in the purified diesel engine exhaust gas is 207ppm, and the ammonia escape is 1 ppm.

Experimental validation example 8

The system is installed on a 6S50-MEC 8.5 marine low-speed diesel engine (rated power 9960KW, rotating speed 127rpm), and the fuel oil is low-sulfur oil (MGO). At 100% load on the diesel engine, the new HP-SCR system starts to operate after switching to Tier III mode of operation. The reducing agent supply unit conveys the 40 wt% urea solution to the reducing agent injection unit, and the urea solution is directly injected into an exhaust manifold of the diesel engine and then enters the SCR reactor along with the exhaust gas to carry out denitration reaction. When the ammonia nitrogen ratio is 0.95, the detection shows that the concentration of NOx in the purified diesel engine exhaust gas is 178ppm, and the ammonia escape is 1 ppm.

Experimental validation example 9

The system is installed on an MAN 6L23-30H marine auxiliary engine diesel engine (rated power 852KW, rotating speed 720rpm), and the fuel oil is low sulfur oil (MGO). At 75% load, the diesel engine is switched to Tier III mode of operation and the new HP-SCR system begins operation. The reducing agent supply unit conveys the 40 wt% urea solution to the reducing agent injection unit, and the urea solution is directly injected into an exhaust manifold of the diesel engine and then enters the SCR reactor along with the exhaust gas to carry out denitration reaction. When the ammonia nitrogen ratio is 0.85, the detection shows that the concentration of NOx in the purified diesel engine exhaust gas is 169ppm, and the ammonia escape is 2 ppm.

Experimental validation example 10

The system is installed on a MAN 6L23-30H marine medium-speed auxiliary engine diesel engine (rated power 852KW, rotating speed 720rpm), and the fuel oil is low-sulfur oil (MGO). When the diesel engine is at 100% load, the diesel engine is switched to a Tier III operation mode, and the novel LP-SCR system starts to operate. The reducing agent supply unit conveys the 40. wt% urea solution to the reducing agent injection unit, and the urea solution is directly injected into an exhaust manifold of the diesel engine, and enters the SCR reactor to carry out denitration reaction after acting by the supercharger. When the ammonia nitrogen ratio is 0.95, the detection shows that the concentration of NOx in the purified diesel engine exhaust gas is 174ppm, and the ammonia escape is 1 ppm.

Experimental validation example 11

The system is installed on a 6S50-MEC 8.5 marine low-speed diesel engine (rated power 9960KW, rotating speed 127rpm), and the fuel oil is Marine Diesel Oil (MDO). At 75% load on the diesel engine, the new HP-SCR system starts to operate after switching to Tier III mode of operation. The reducing agent supply unit conveys the 40 wt% urea solution to the reducing agent injection unit, and the urea solution is directly injected into an exhaust manifold of the diesel engine and then enters the SCR reactor along with the exhaust gas to carry out denitration reaction. When the ammonia nitrogen ratio is 0.85, the detection shows that the concentration of NOx in the purified diesel engine exhaust gas is 219ppm, and the ammonia escape is 3 ppm.

Experimental validation example 12

The system is installed on a 6S50-MEC 8.5 marine low-speed diesel engine (rated power 9960KW, rotating speed 127rpm), and the fuel oil is low-sulfur oil (MGO). At 75% load on the diesel engine, the new HP-SCR system starts to operate after switching to Tier III mode of operation. The reducing agent supply unit conveys 20 wt.% ammonia water to the reducing agent injection unit, and the ammonia water is directly injected into an exhaust manifold of the diesel engine and then enters the SCR reactor along with exhaust gas to carry out denitration reaction. When the ammonia nitrogen ratio is 0.85, the detection shows that the concentration of NOx in the purified diesel engine exhaust gas is 203ppm, and the ammonia escape is 1 ppm.

Finally, it should be noted that: the above examples are only intended to illustrate the technical solution of the present invention, but not to limit it; although the present invention has been described in detail with reference to the foregoing embodiments, it will be understood by those of ordinary skill in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some technical features may be equivalently replaced; and such modifications or substitutions do not depart from the spirit and scope of the corresponding technical solutions of the embodiments of the present invention.