CN212563395U

CN212563395U - Independent SCR system for centralized processing of nitrogen oxides

Info

Publication number: CN212563395U
Application number: CN202021239786.XU
Authority: CN
Inventors: 王学柏; 魏立江; 史兆飞; 张明红
Original assignee: KUNSHAN JIANGJIN MACHINERY CO Ltd; Shanghai Maritime University
Current assignee: KUNSHAN JIANGJIN MACHINERY CO Ltd; Shanghai Maritime University
Priority date: 2020-06-30
Filing date: 2020-06-30
Publication date: 2021-02-19
Anticipated expiration: 2030-06-30

Abstract

The utility model discloses a centralized processing nitrogen oxide's stand alone type SCR system, it includes that control unit (22) and tail gas introduction portion (1), the oil spout that connects gradually raise temperature portion (2), rectification measuring part (3), catalytic reaction portion (4) and feedback measuring part (5), control unit (22) are controlled to whole system, the tail gas of leading-in many diesel engines of tail gas introduction portion (1). The utility model discloses a centralized processing nitrogen oxide's stand alone type SCR system is provided with the tail gas leading-in portion that is used for leading-in many diesel engine tail gas, many diesel engines on the equipment can concentrate through an SCR system and carry out the tail gas treatment, reduce traditional many sets of SCR systems to one set, can effectively reduce the quantity of installing component, save installation space, reduce the construction cost of equipment such as boats and ships, can alleviate the work load of routine maintenance and maintenance simultaneously, do benefit to the reliable operation of equipment.

Description

Independent SCR system for centralized processing of nitrogen oxides

Technical Field

The utility model relates to a SCR system, in particular to stand alone type SCR system of centralized processing nitrogen oxide.

Background

Diesel engines produce a large amount of nitrogen oxides (NOx) which are toxic pollutants to be controlled when they operate, and thus, they are widely equipped with SCR systems. SCR, selective catalytic reduction, is a treatment process for nitrogen oxides in the exhaust emission of diesel engines, i.e. under the action of a catalyst, a reducing agent ammonia or urea is sprayed in to reduce the nitrogen oxides in the exhaust into N₂And H₂And O. A complete set of SCR systems includes numerous components such as a urea tank, a dosing pump, a DCU (i.e., urea injection control unit), a urea nozzle, a catalyst, and various sensors. After the SCR system is added into a diesel engine system, the SCR system has a coupling relation with a corresponding diesel engine, on one hand, a DCU of the SCR system can determine the injection amount of urea according to the information of the rotating speed, the torque and the like of the diesel engine; on the other hand, the SCR system becomes a subsystem of the diesel engine system, and directly affects the operating performance of the diesel engine.

At present, some large-scale equipment is usually equipped with a plurality of diesel engines, for example, ocean vessels, one ocean vessel is often equipped with 2-4 diesel engines for power generation and 1-2 diesel engines for propulsion, and in the prior art, each diesel engine is equipped with one set of SCR system, and this distributed SCR arrangement form leads to one ocean vessel needing to install a plurality of complete sets of SCR systems, which not only occupies a large amount of vessel space, and causes the increase of the use amount of parts such as urea tanks and metering pumps and the construction cost of the vessel, but also brings troubles for the filling of urea and the overhaul of the SCR system, especially, a plurality of diesel engines on the vessel are often arranged in different cabins, and this greatly increases the workload of daily maintenance of the SCR system. The trouble of maintenance has also increased the not in place probability of SCR system maintenance simultaneously, and in case the SCR system of equipment breaks down, because the existence of current SCR system and corresponding diesel engine coupling relation, the diesel engine that the SCR system corresponds also will work unusually, has increased the probability that the diesel engine broke down, is unfavorable for the reliable operation of equipment.

SUMMERY OF THE UTILITY MODEL

An object of the utility model is to the above-mentioned defect among the prior art, provide a stand alone type SCR system of centralized processing nitrogen oxide, can reduce the SCR system quantity of installation on the boats and ships, reduce equipment construction cost and daily maintenance work load to be favorable to the reliable operation of equipment.

In order to realize the utility model discloses the purpose, the utility model provides a stand alone type SCR system of centralized processing nitrogen oxide, its tail gas leading-in portion, the oil spout that includes the control unit and connect gradually carries temperature portion, rectification measuring part, catalytic reaction portion and feedback measuring part, the control unit controls entire system, the leading-in tail gas of many diesel engines of tail gas leading-in portion.

Furthermore, the utility model discloses still provide following subsidiary technical scheme:

the tail gas leading-in part comprises a plurality of branch pipes, and the branch pipes are connected with a tail gas discharge pipeline of the diesel engine.

The branch pipe is provided with a valve, when the diesel engine corresponding to the branch pipe works, the opening degree of the valve is 100%, and when the diesel engine corresponding to the branch pipe stops, the opening degree of the valve is 0%.

The oil injection temperature raising portion comprises a temperature raising cavity and a diesel oil supply system, the diesel oil supply system raises the temperature of gas in the temperature raising cavity by injecting diesel oil into the temperature raising cavity and igniting the diesel oil, and the diesel oil supply system is in communication connection with the control unit.

The control unit controls the diesel supply system to inject diesel based on measured values of gas temperature, pressure, nitrogen oxide concentration, and oxygen concentration in the rectification measurement section.

The rectification measuring part comprises a connecting pipe connected with the oil injection temperature raising part and a first temperature sensor, a pressure sensor, a first nitrogen oxide sensor and an oxygen sensor which are used for measuring the temperature, the pressure, the concentration of nitrogen oxide and the concentration of oxygen of the gas in the connecting pipe respectively, and the first temperature sensor, the pressure sensor, the first nitrogen oxide sensor and the oxygen sensor are in communication connection with the control unit.

The rectification measuring part also comprises a rectification net positioned at the inlet of the connecting pipe.

The catalytic reaction part comprises a urea supply system, a urea injection system and a catalyst, wherein the urea supply system injects urea aqueous solution into the catalyst through the urea injection system.

The feedback measuring part comprises a second temperature sensor, a second oxynitride sensor and an ammonia gas sensor which are respectively used for measuring the temperature, the oxynitride concentration and the ammonia gas concentration of the gas discharged from the catalytic reaction part, and the second temperature sensor, the second oxynitride sensor and the ammonia gas sensor are in communication connection with the control unit.

And the control unit finally determines the injection quantity of the urea by adopting a closed-loop control method by combining the measured values of the temperature, the pressure, the concentration of the nitrogen oxides and the concentration of the oxygen in the rectification measuring part and the concentration values of the nitrogen oxides and the ammonia in the feedback measuring part.

Compared with the prior art, the utility model has the advantages of:

1. the utility model discloses an independent type SCR system of centralized processing nitrogen oxide is provided with the tail gas leading-in portion that is used for leading in many diesel engine tail gases, and many diesel engines on the equipment can concentrate through an SCR system and carry out the tail gas treatment, reduces traditional many sets of SCR systems into one set, can effectively reduce the quantity of installation component, saves installation space, reduces the construction cost of equipment such as boats and ships;

2. the independent SCR system for centralized processing of nitrogen oxide can perform centralized processing on tail gas of a plurality of diesel engines, only one set of SCR system needs to be overhauled and maintained, the system is very convenient, and the workload of daily overhaul and maintenance is greatly reduced; meanwhile, a set of SCR system is overhauled and maintained, so that the probability of improper overhaul can be effectively reduced, the probability of failure of the SCR system and a diesel engine is reduced, and the equipment is more reliable to operate;

3. the utility model discloses a there is not coupling relation in stand alone type SCR system of centralized processing nitrogen oxide and each diesel engine, need not the jet volume of information such as the rotational speed, the moment of torsion according to the diesel engine and decide urea, directly according to the temperature of rectification measuring part, pressure and nitrogen oxide concentration value isoparametric to and the nitrogen oxide of feedback measuring part and ammonia concentration value isoparametric, adopt the jet volume of closed-loop control method definite urea, even there is the diesel engine to break down can not influence the independence of SCR system, the reliable operation yet.

Drawings

Fig. 1 is a schematic diagram of a standalone SCR system for centralized treatment of nitrogen oxides according to the present invention.

Detailed Description

The following non-limiting detailed description of the present invention is provided in connection with the preferred embodiments and accompanying drawings.

As shown in fig. 1, the independent SCR system for centralized nitrogen oxide treatment according to a preferred embodiment of the present invention includes a tail gas introduction portion 1, an oil injection temperature raising portion 2, a rectification measurement portion 3, a catalytic reaction portion 4, a feedback measurement portion 5, and a control unit 22.

The tail gas leading-in part 1, the oil injection temperature raising part 2, the rectification measuring part 3, the catalytic reaction part 4 and the feedback measuring part 5 are connected in sequence, and the control unit 22 controls the whole system.

The exhaust gas introducing portion 1 includes an intake pipe 24 and a plurality of branch pipes 6 connected to the intake pipe 24. The number of the branch pipes 6 is equal to the number of the diesel engines mounted on the ship, and the branch pipes are connected with an exhaust emission pipeline of the diesel engines and used for guiding the exhaust of each diesel engine into the air inlet pipe 24. A valve 7 is mounted on each branch pipe 6, the valve 7 preferably being an electrically or pneumatically operated butterfly valve, the opening and closing of which can be controlled electrically or pneumatically. The opening of the valve 7 can be set to two steps: 0% opening and 100% opening, the on-off logic of the valve 7 is set as follows: when the diesel engine corresponding to the branch pipe 6 works, the valve opening is set to be 100%, and when the diesel engine corresponding to the branch pipe 6 stops, the valve opening is set to be 0%.

Above-mentioned oil spout is carried temperature portion 2 and is contained and carry temperature chamber 25 and one set of diesel oil supply system 8 that is linked together with intake pipe 24, diesel oil supply system 8 is including setting up diesel nozzle 9 and ignition in carrying temperature chamber 25, spray diesel oil in carrying temperature chamber 25's tail gas through diesel nozzle 9, and light diesel oil through ignition and burn, improve the temperature of carrying temperature chamber 25 internal tail gas, because the temperature of starting up of catalyst is higher relatively with best operating temperature in catalytic reaction portion 4, the utility model discloses a set up the oil spout and carry temperature portion 2 and improve the temperature of tail gas, be in the highest or higher temperature of catalytic efficiency when can making tail gas remove catalytic reaction portion 4, thereby improve catalytic efficiency, influence catalytic efficiency because of the tail gas temperature can drop to below the catalyst activity temperature. The temperature is raised by burning diesel oil, the produced pollutants are basically consistent with tail gas discharged by a diesel engine, and new pollutants can not be introduced. The diesel supply system 8 is connected to the control unit 22 in communication, and is controlled by the control unit 22.

The rectification measuring part 3 comprises a connecting pipe 26 connected with the temperature raising cavity 25, the connecting pipe 26 is preferably a straight pipe structure and comprises a rectification section 10 and a measuring section 11, and the rectification section 10 is positioned in front of the measuring section 11. A rectifying net 12 is arranged at an inlet of the rectifying section 10 and used for rectifying the incoming flow of the oil spraying temperature raising part 2 and promoting mixing, and preferably, the rectifying net 12 is a stainless steel wire net; the measuring section 11 is provided with a first temperature sensor 13, a pressure sensor 14, a first nitrogen oxide sensor 15 and an oxygen sensor 23, which are used for measuring the temperature, the pressure, the nitrogen oxide concentration and the oxygen concentration of the incoming flow. The first temperature sensor 13, the pressure sensor 14, the first nitrogen oxide sensor 15 and the oxygen sensor 23 are connected in communication with the control unit 22, and the detected values are transmitted to the control unit 22.

The catalytic reaction portion 4 includes a urea supply system 16, a urea injection system 17, and a catalyst 18. The catalyst 18 is connected to a connection pipe 26, the urea supply system 16 is connected to a urea injection system 17, and the urea injection system 17 is disposed in front of the catalyst 18 and includes a urea nozzle 28 installed at an inlet of the catalyst 18, and urea aqueous solution is injected into the pipe through the urea nozzle 28. The tail gas is catalytically reduced in the catalyst 18 to be purified, and the size of the catalyst 18 is determined according to the sum of the maximum exhaust amount of each diesel engine started when the ship normally works. The urea supply system 16 is provided with a heating device capable of heating urea. The urea supply system 16 and the urea injection system 17 are both connected in communication with the control unit 22 and controlled by the control unit 22.

The feedback measuring part 5 includes an exhaust pipe 27 connected to the catalyst 18, and a second temperature sensor 19, a second nox sensor 20 and an ammonia gas sensor 21 mounted on the exhaust pipe 27, and is configured to measure the content of pollutants in the exhaust gas after passing through the catalytic reaction part 4, wherein the second temperature sensor 19, the second nox sensor 20 and the ammonia gas sensor 21 respectively detect the temperature, the nox concentration and the ammonia gas concentration of the gas, and are in communication connection with the control unit 22, and can transmit the measured values to the control unit 22.

The control unit 22 is mainly used for receiving and processing data sent by each sensor and realizing control over diesel injection in the fuel injection temperature raising part 2, control over urea injection in the catalytic reaction part 4 and heating control over the urea supply system 16.

The control unit 22 controls the diesel injection in the oil injection temperature raising part 2 by the following method: whether the fuel injection temperature raising unit 2 injects the diesel fuel and the amount of the diesel fuel injected are determined based on the measured values of the gas temperature, the pressure, the nox concentration, and the oxygen concentration in the rectification measuring unit 3. Usually, the temperature of the tail gas determines whether the diesel oil needs to be injected, and when the temperature of the tail gas is higher than the activation temperature of the catalyst in the catalytic reaction part 4, the injection amount of the diesel oil is 0, namely the diesel oil does not need to be injected; when the temperature of the tail gas is lower than the catalyst activation temperature, diesel oil needs to be injected to burn to improve the temperature of the tail gas, the injection amount of the diesel oil needs to be calculated according to the temperature and the pressure of the tail gas, and the more the temperature of the tail gas is lower than the catalyst activation temperature, the larger the amount of the diesel oil needs to be injected. The concentration of nitrogen oxides and the concentration of oxygen in the exhaust gas have a correcting effect on the actual injection quantity of the diesel.

The control means 22 controls the urea injection in the catalytic reaction portion 4 by: firstly, the content of nitrogen oxides in the tail gas is calculated according to the measured values of the temperature, the pressure and the concentration of the nitrogen oxides in the rectification measuring part 3, the urea injection quantity is preliminarily determined, and then the urea injection quantity is finally determined by adopting a closed-loop control method according to the concentration values of the nitrogen oxides and the ammonia gas given in the feedback measuring part 5.

Specifically, the nitrogen oxide and ammonia concentration values in the feedback measurement section 5 can be corrected in a closed loop manner for the urea injection amount: after passing through the catalytic reaction part 4, the nitrogen oxide in the feedback measurement part 5 should be reduced, if the nitrogen oxide in the feedback measurement part 5 is not lower than the target value, the urea injection amount needs to be further increased, if the nitrogen oxide is lower than the target value, the urea injection amount is enough or redundant, at this time, the judgment needs to be carried out according to the ammonia gas concentration value, and if the ammonia gas concentration value is higher, the urea injection amount needs to be reduced if the urea injection amount is too much.

The control unit 22 controls the heating of the urea supply system 16 by switching on the heating circuit when it is detected that the temperature of the urea solution is lower than a limit value, and heating the urea solution and the supply line to prevent the urea solution from crystallizing or solidifying at low temperature, thereby causing blockage of the line and the nozzle.

The utility model discloses a centralized processing nitrogen oxide's stand alone type SCR system includes following advantage at least:

It should be noted that the above-mentioned preferred embodiments are only for illustrating the technical concepts and features of the present invention, and the purpose thereof is to enable those skilled in the art to understand the contents of the present invention and to implement the present invention accordingly, and the protection scope of the present invention cannot be limited thereby. All equivalent changes and modifications made according to the spirit of the present invention should be covered by the protection scope of the present invention.

Claims

1. A self-contained SCR system for centrally treating nitrogen oxides, characterized by: the diesel engine tail gas temperature-raising device comprises a control unit (22) and a tail gas leading-in portion (1), an oil injection temperature-raising portion (2), a rectification measuring portion (3), a catalytic reaction portion (4) and a feedback measuring portion (5) which are sequentially connected, wherein the control unit (22) controls the whole system, and the tail gas leading-in portion (1) leads in tail gas of a plurality of diesel engines.

2. A self-contained SCR system for the centralized treatment of nitrogen oxides as recited in claim 1, wherein: the tail gas leading-in part (1) comprises a plurality of branch pipes (6), and the branch pipes (6) are connected with a tail gas discharge pipeline of the diesel engine.

3. A self-contained SCR system for the centralized treatment of nitrogen oxides as recited in claim 2, wherein: be provided with valve (7) on branch pipe (6), the diesel engine during operation that branch pipe (6) correspond, the aperture of valve (7) is 100%, when the diesel engine that branch pipe (6) correspond shut down, the aperture of valve (7) is 0%.

4. A self-contained SCR system for the centralized treatment of nitrogen oxides as recited in claim 1, wherein: the oil injection temperature raising portion (2) comprises a temperature raising cavity (25) and a diesel oil supply system (8), the diesel oil supply system (8) raises the temperature of gas in the temperature raising cavity (25) by injecting diesel oil into the temperature raising cavity (25) and igniting the diesel oil, and the diesel oil supply system (8) is in communication connection with the control unit (22).

5. A self-contained SCR system for the centralized treatment of nitrogen oxides as recited in claim 4, wherein: the control unit (22) controls the diesel supply system (8) to inject diesel based on the measured values of the gas temperature, pressure, nitrogen oxide concentration, and oxygen concentration in the rectification measurement section (3).

6. A self-contained SCR system for the centralized treatment of nitrogen oxides as recited in claim 1, wherein: the rectification measuring part (3) comprises a connecting pipe (26) connected with the oil injection temperature raising part (2) and a first temperature sensor (13), a pressure sensor (14), a first nitrogen oxide sensor (15) and an oxygen sensor (23) which are used for measuring the temperature, the pressure, the concentration of nitrogen oxide and the concentration of oxygen in the connecting pipe (26) respectively, wherein the first temperature sensor (13), the pressure sensor (14), the first nitrogen oxide sensor (15) and the oxygen sensor (23) are in communication connection with the control unit (22).

7. A self-contained SCR system for the centralized treatment of nitrogen oxides as recited in claim 6, wherein: the rectification measuring part (3) further comprises a rectification net (12) positioned at the inlet of the connecting pipe (26).

8. A self-contained SCR system for the centralized treatment of nitrogen oxides as recited in claim 1, wherein: the catalytic reaction part (4) comprises a urea supply system (16), a urea injection system (17) and a catalyst (18), wherein the urea supply system (16) injects urea aqueous solution into the catalyst (18) through the urea injection system (17).

9. A self-contained SCR system for the centralized treatment of nitrogen oxides as recited in claim 1, wherein: the feedback measuring part (5) comprises a second temperature sensor (19), a second oxynitride sensor (20) and an ammonia gas sensor (21) which respectively measure the temperature, the concentration of nitrogen oxides and the concentration of ammonia gas discharged from the catalytic reaction part (4), and the second temperature sensor (19), the second oxynitride sensor (20) and the ammonia gas sensor (21) are in communication connection with the control unit (22).

10. A self-contained SCR system for the centralized treatment of nitrogen oxides as recited in claim 9, wherein: the control unit (22) combines the measured values of the temperature, the pressure, the concentration of the nitrogen oxides and the concentration of the oxygen in the rectification measuring part (3) and the concentration values of the nitrogen oxides and the ammonia in the feedback measuring part (5) to finally determine the injection quantity of the urea by adopting a closed-loop control method.