CN206845280U

CN206845280U - A kind of exhaust gas purification system of marine diesel engine

Info

Publication number: CN206845280U
Application number: CN201720780942.5U
Authority: CN
Inventors: 李剑峰; 暴辰生; 周文忠; 顾维哲; 陆维光; 崔广涛; 郭星萌
Original assignee: Suzhou Shuimukangqiao Environmental Engineering Technology Co Ltd
Current assignee: Suzhou Shuimukangqiao Environmental Engineering Technology Co Ltd
Priority date: 2017-06-30
Filing date: 2017-06-30
Publication date: 2018-01-05
Anticipated expiration: 2027-06-30

Abstract

The utility model provides a kind of exhaust gas purification system of marine diesel engine, belongs to environmental technology field.The exhaust gas purification system includes the particulate matter filter device sequentially set and catalysis oxidation/reduction apparatus；Wherein, the particulate matter filter device is grain bed, for removing the particulate matter of PM2.5 levels and the above；Catalysis oxidation/the reduction apparatus is multistage reactor, for removing denitrification, carbon monoxide and hydro carbons.Gaseous urea liquid is directly sufficiently mixed with high-temperature tail gas in the utility model, so as to produce gaseous ammonia, it instead of the gaseous ammonia generating means in conventional art, the structure of exhaust purifier provided by the utility model is simple, small volume, in light weight, more for practicality.In addition, also add secondary reactor, carrying out effective catalysis to carbon monoxide and hydro carbons reduces, and reaches the purpose reliably purified.

Description

Tail gas purification system of diesel engine for ship

Technical Field

The utility model relates to a tail gas clean system of diesel engine for boats and ships.

Background

The shipping industry is developing rapidly and becoming the mainstay of logistics, and the port in 2015 nationwide completes 107.8 hundred million tons of cargo, wherein the foreign trade throughput is 30.6 hundred million tons, which is 38 and 51 times that in 1978, respectively, and the port throughput is kept world first for many years.

However, the tail gas emission of the marine diesel engine is as follows: the emission harm is large, the discharge amount is large, and the pollution is serious. The exhaust gas of the ship contains exhaust pollutants such as carbon monoxide, hydrocarbon, oxynitride, sulfur dioxide, particulate matters and the like. The national environmental protection agency places more than 40 compounds emitted by diesel engines in the list of Hazardous Air Pollutants (HAPs), such as: formaldehyde, acetaldehyde, 1, 3-butadiene, benzene, polycyclic aromatic hydrocarbons, and compounds of metals such as arsenic, lead, mercury, and manganese.

In relevant regulations, national laws and regulations raise emission requirements for environmental protection requirements. For example, a series of relevant laws and regulations such as air pollution control law are officially implemented, and the ministry of environmental protection promulgates "emission limit of exhaust pollutants of ship engines and measurement methods (first and second stages in china) (GB 15097-2016).

But the current research situation of the ship tail gas treatment technology is as follows: monopoly abroad and blank at home. Compared with developed countries, the first stage of GB15097-2016 is equivalent to the standard implemented in Europe, and the second stage is equivalent to the standard implemented in the third stage of the United states.

Diesel oil used by diesel engines contains a large amount of oil substances with high ignition points, so that the diesel oil is combusted in a cylinder of the diesel engine far less thoroughly than light oil, and thus tail gas contains a large amount of toxic and harmful substances including carbon monoxide, sulfur dioxide, nitrogen oxides, hydrocarbons, and even micro-droplet oil and pitch-like substances which are not combusted. The substances enter the SCR device at the later stage to cause the blockage of the ceramic catalyst in the SCR device, thereby greatly reducing the service life of the SCR device and causing the high-price ceramic catalyst to be invalid and scrapped.

In addition, ammonia gas and nitrogen oxides are adopted in the SCR device to react to remove the nitrogen oxides, but the ammonia gas has potential safety hazards in the use process due to instability of the ammonia gas.

SUMMERY OF THE UTILITY MODEL

An object of the utility model is to provide a tail gas clean-up system for diesel engine for boats and ships (power is greater than 37 kw), not only can make diesel engine tail gas level reach national GB15097-2016 marine engine exhaust pollutant emission limit value and measuring method "second stage emission level, can also guarantee the security among the purifying process, and compared with current clean-up system has reduced the purification cost.

Particularly, the utility model provides a tail gas purification system of a marine diesel engine, which comprises a particulate matter filtering device and a catalytic oxidation/reduction device which are arranged in sequence;

wherein,

the particulate matter filtering device is a particulate bed and is used for removing particulate matters with PM2.5 grade and above;

the catalytic oxidation/reduction unit is a multistage reactor for removing nitrogen oxides, carbon monoxide and hydrocarbons.

For the technical scheme, the inventor also has further optimized implementation measures.

Preferably, the catalytic oxidation/reduction device comprises an SCR reactor for removing nitrogen oxides, a catalytic converter and a sprayer are arranged in the SCR reactor, and the sprayer is used for spraying urea solution into the SCR reactor.

Further, NO is arranged at the air inlet end of the SCR reactor_XA sensor for detecting NO in the exhaust gas entering the SCR reactor_XAccording to the opening degree of the atomizer according to NO_XThe detection signal of the sensor is adjusted.

Further, the sprayer is a metering sprayer, the SCR reactor also comprises an electronic control unit, and the NO is_XAnd sending a detection signal of the sensor to an electric control unit, and sending a control signal by the electric control unit to control the amount of the urea solution sprayed by the metering sprayer.

Preferably, the catalytic oxidation/reduction device further comprises a secondary reactor for removing carbon monoxide and hydrocarbons, and the gas inlet end of the secondary reactor is connected with the gas outlet end of the SCR reactor.

Further, the secondary reactor comprises a spherical catalytic carrier arranged in the closed shell, wherein the spherical catalytic carrier is formed by forming a nanoscale coating on the surface of a nanoscale Pt and Pa noble metal, and the thickness of the coating is 50-200 nm.

Still further, the spherical catalytic carrier is a honeycomb catalytic carrier.

The utility model discloses a tail gas clean system directly carries the urea solution to the SCR reactor in the catalytic oxidation reduction device through the pipeline in for urea solution and high temperature tail gas carry out intensive mixing, thereby produce gaseous ammonia, just so need not the gaseous ammonia generation device that prior art was commonly used, replaced gaseous ammonia generation device that comprises huge equipment such as ammonia evaporimeter, ammonia buffer tank, gas flow valve in the selective catalytic reduction method, this is for removing pollution source diesel engine to the majority, the utility model provides a tail gas clean system's simple structure, small, light in weight more possess the practicality. In addition, a secondary reactor is added to effectively catalyze and reduce carbon monoxide and hydrocarbons, so that the purpose of reliable purification is achieved.

Further, the utility model discloses NO with nitrogen oxide content in the high temperature tail gas of detection_XThe sensor, the injection volume of urea solution is according to nitrogen oxide content in tail gas clean system's the high temperature tail gas carries out intelligent control, when guaranteeing that high efficiency takes out nitrogen oxide, can also avoid the emergence of the ammonia escape condition, has practiced thrift the cost, and has avoided secondary environmental pollution.

The above and other objects, advantages and features of the present invention will become more apparent to those skilled in the art from the following detailed description of specific embodiments thereof, taken in conjunction with the accompanying drawings.

Drawings

Some specific embodiments of the present invention will be described in detail hereinafter, by way of illustration and not by way of limitation, with reference to the accompanying drawings. The same reference numbers in the drawings identify the same or similar elements or components. Those skilled in the art will appreciate that the drawings are not necessarily drawn to scale. In the drawings:

fig. 1 is a schematic structural diagram of an exhaust gas purification system according to an embodiment of the present invention.

Wherein:

1. a particulate matter filtering device; 2. an SCR reactor; 3. a secondary reactor; 4. a sprayer; 5. NO_XA sensor; 6. an electronic control unit.

Detailed Description

As shown in fig. 1, the exhaust gas purification system of the marine diesel engine described in this embodiment may generally include a particulate matter filtering device 1 and a catalytic oxidation/reduction device arranged in sequence; wherein the particulate matter filtering device 1 is a particulate bed for removing particulate matter of PM2.5 level or above; the catalytic oxidation/reduction unit is a multistage reactor for removing nitrogen oxides, carbon monoxide and hydrocarbons.

The multistage reactor can remove nitrogen oxides, carbon monoxide and hydrocarbons in sequence, the reaction is more sufficient, the purification effect is better, and the purpose of reliable purification can be achieved.

Preferably, the catalytic oxidation/reduction device comprises an SCR reactor 2 for removing nitrogen oxides, a catalytic converter and a sprayer 4 are arranged in the SCR reactor 2, and the sprayer 4 is used for spraying urea solution into the SCR reactor 2.

A pipeline is arranged in the SCR reactor 2, the urea solution is conveyed to the sprayer 4 through the pipeline and then enters the SCR reactor 2, the urea solution is changed into a micro-droplet state through airflow spraying and is fully mixed with high-temperature tail gas, and the urea in the urea solution is rapidly heated to above 160 ℃ under the action of the high-temperature tail gas to be further decomposed to generate gaseous ammonia (NH)₃) And biuret (CONH), with gaseous ammonia (NH)₃) Will react with nitrogen oxides (including NO and NO) in the exhaust gas under catalytic conditions₂) The following chemical reactions take place:

4NH₃+4NO+O₂=4N₂+6H₂O

8NH₃+6NO₂=7N₂+12H₂O

simultaneously with the denitration treatment, under the conditions of high temperature and catalysis, the carbon monoxide and the nitrogen oxides (including NO and NO) in the tail gas mixed gas₂) The following chemical reactions take place:

2CO+2NO+O₂=2CO₂+N₂

4CO+2NO₂=4CO₂+ N₂

thus, the catalytic reduction removal of nitrogen oxides is realized, a large amount of carbon monoxide is removed, and the tail gas purification effect is obvious.

It will be appreciated that the content of nitrogen oxides entering the exhaust gas purifier is constantly changing, and that the nitrogen oxides produced are necessarily different due to different operating conditions of the diesel engine, and thus the gaseous ammonia required to purify these main pollutants, i.e. nitrogen oxides, is different. In this case, the inventors provided NO at the inlet end of the SCR reactor 2, where the exhaust gases were discharged_XA sensor 5 for detecting NO in the exhaust gas entering the SCR reactor 2_XAccording to the opening degree of the atomizer 4 to NO_XThe detection signal of the sensor 5 is adjusted.

In order to avoid the insufficient injection amount of the urea solution or the excessive injection of the urea solution, the excessive injection amount of the urea solution entering the exhaust gas purification device must be changed immediately according to the change of the working condition of the diesel engine (the flow rate of the exhaust gas is different and the concentration of nitrogen oxides contained in the exhaust gas is different due to the difference of the rotating speed and the load). Further, the sprayer 4 is a metering sprayer 4, and the electronic control spraying is carried out by an electronic control unit 6 in the SCR reactor 2 according to the concentration of the urea solution. In said NO_XAfter the detection signal of the sensor 5 is sent to the electronic control unit 6, the information processing is carried out, and then the electronic control unit 6 sends out a control signal again to control the amount of the urea solution sprayed by the metering sprayer 4.

Since a certain amount of carbon monoxide has been previously removed in the SCR reactor 2, but there may be residues, a secondary reactor 3 for removing carbon monoxide and hydrocarbons may be further provided in the catalytic oxidation/reduction unit, and the gas inlet end of the secondary reactor 3 is connected to the gas outlet end of the SCR reactor 2, that is, is provided at the rear end of the SCR reactor 2.

Further, the secondary reactor 3 comprises a spherical catalytic carrier arranged in a closed shell, the spherical catalytic carrier is a nano-scale coating formed on the surface of nano-scale Pt and Pa noble metal, the thickness of the coating is 50-200nm, and the spherical catalytic carrier is a honeycomb catalytic carrier. The honeycomb structure not only can ensure that the tail gas is discharged smoothly, but also has larger contact reaction area and more sufficient reaction.

In conclusion, the tail gas clean system of this embodiment, directly carry the urea solution to SCR reactor 2 in the catalytic oxidation/reduction device through the pipeline in for urea solution and high temperature tail gas carry out intensive mixing, thereby produce gaseous ammonia and biuret, just so need not the gaseous ammonia generating device that prior art was commonly used, gaseous ammonia generating device who comprises huge equipment such as ammonia evaporator, ammonia buffer tank, gas flow valve in having replaced the selective catalytic reduction method, this is for removing pollution source diesel engine to the majority, the utility model provides a tail gas clean system's simple structure, small, light in weight, more possess the practicality. In addition, a secondary reactor 3 is added to effectively catalyze and reduce carbon monoxide and hydrocarbons, so that the purpose of reliable purification is achieved.

Furthermore, the utility model discloses NO with nitrogen oxide content in the high temperature tail gas of detection_XSensor 5, the injection quantity of urea solution is according to nitrogen oxide content in tail gas clean system's the high temperature tail gas carries out intelligent control, when guaranteeing that high efficiency takes out nitrogen oxide, can also avoid the emergence of the ammonia escape condition, has practiced thrift the cost, and has avoided the pollution of environment.

Thus, it should be appreciated by those skilled in the art that while a number of exemplary embodiments of the invention have been shown and described in detail herein, many other variations and modifications can be made, consistent with the principles of the invention, which are directly determined or derived from the disclosure herein, without departing from the spirit and scope of the invention. Accordingly, the scope of the present invention should be understood and interpreted to cover all such other variations or modifications.

Claims

1. An exhaust gas purification system of a marine diesel engine comprises a particulate matter filtering device and a catalytic oxidation/reduction device which are arranged in sequence;

wherein,

2. The exhaust gas purification system according to claim 1, wherein the catalytic oxidation/reduction device comprises an SCR reactor for removing nitrogen oxides, a catalytic converter and an atomizer being provided in the SCR reactor, the atomizer being configured to inject a urea solution into the SCR reactor.

3. Exhaust gas purification system according to claim 2, wherein NO is provided at the inlet end of the SCR reactor_XA sensor for detecting NO in the exhaust gas entering the SCR reactor_XAccording to the opening degree of the atomizer according to NO_XThe detection signal of the sensor is adjusted.

4. The exhaust gas purification system according to claim 3, wherein the nebulizer is a metered nebulizer, the SCR reactor further comprising an electronic control unit therein, the NO being_XAnd sending a detection signal of the sensor to an electric control unit, and sending a control signal by the electric control unit to control the amount of the urea solution sprayed by the metering sprayer.

5. The exhaust gas purification system according to claim 2, wherein the catalytic oxidation/reduction unit further comprises a secondary reactor for removing carbon monoxide and hydrocarbons, and a gas inlet end of the secondary reactor is connected to a gas outlet end of the SCR reactor.

6. The exhaust gas purification system according to claim 5, wherein the secondary reactor comprises a spherical catalytic carrier arranged in a closed shell, the spherical catalytic carrier is formed by forming a nano-scale coating on the surface of a nano-scale Pt and Pa noble metal, and the thickness of the coating is 50-200 nm.

7. The exhaust gas purification system according to claim 6, wherein the spherical catalytic carrier is a honeycomb catalytic carrier.