CN211913352U

CN211913352U - Tail gas aftertreatment system

Info

Publication number: CN211913352U
Application number: CN202020514725.3U
Authority: CN
Inventors: 彭学磊; 陈迪; 孙树平; 牛瑞祥; 郑祥
Original assignee: Tenneco Suzhou Emission System Co Ltd
Current assignee: Tenneco Suzhou Emission System Co Ltd
Priority date: 2020-04-10
Filing date: 2020-04-10
Publication date: 2020-11-13
Anticipated expiration: 2030-04-10

Abstract

An exhaust aftertreatment system comprises an exhaust pipeline, a packaging system, a urea injection system and a control system. The exhaust pipeline comprises a main exhaust pipeline and a bypass pipeline. The main exhaust pipeline is provided with a first valve and a second valve. The bypass pipeline is provided with a bypass valve. The packaging system comprises a particle trap, a selective catalytic reduction agent, a mixer, a first soot blowing valve used for connecting the particle trap with a gas source, and a second soot blowing valve used for connecting the selective catalytic reduction agent with the gas source. By the arrangement, when the particle trap and/or the selective catalytic reducing agent are blocked, the blockage can be removed in a soot blowing mode; when the soot blowing can not eliminate the blockage, the packaging system is maintained by opening the bypass pipeline, so that the convenience of system maintenance is improved.

Description

Tail gas aftertreatment system

Technical Field

The utility model relates to a tail gas aftertreatment system belongs to tail gas aftertreatment technical field.

Background

Because fixed equipment such as boiler, industrial furnace, thermal power plant, large-scale engine test station can produce a large amount of pollutants in the operation process, especially Particulate Matter (PM) and oxynitride (NOx), along with the continuous upgrading of emission regulation, the emission limit value of particulate matter and oxynitride is more and more rigorous, how to remove dust and denitration to improve the convenience of system maintenance, be the technical problem that technical staff of technical field needs to solve urgently.

SUMMERY OF THE UTILITY MODEL

An object of the utility model is to provide a tail gas aftertreatment system convenient to maintain.

In order to achieve the above purpose, the utility model adopts the following technical scheme: an exhaust aftertreatment system comprising an exhaust line, a package system mounted on the exhaust line, a urea injection system for injecting urea droplets into the package system, and a control system for controlling the exhaust aftertreatment system; the exhaust pipeline comprises a main exhaust pipeline and a bypass pipeline, the packaging system is installed in the main exhaust pipeline, the main exhaust pipeline is provided with a first valve installed on the upstream of the packaging system and a second valve installed on the downstream of the packaging system, and the bypass pipeline is provided with a bypass valve; the packaging system comprises a particle trap, a selective catalytic reduction agent positioned at the downstream of the particle trap, a mixer arranged between the particle trap and the selective catalytic reduction agent, a first ash blowing valve used for connecting the particle trap with a gas source, and a second ash blowing valve used for connecting the selective catalytic reduction agent with the gas source; the urea injection system includes a urea nozzle mounted on the packaging system and configured to inject urea droplets toward the mixer; the first valve, the second valve, the bypass valve, the first soot blowing valve, the second soot blowing valve and the urea injection system are all connected with the control system.

As a further improved technical solution of the present invention, when the main exhaust pipeline is turned on, both the first valve and the second valve are opened; the bypass valve is closed, thereby closing the bypass line;

when the bypass pipeline is conducted, the bypass valve is opened; the first valve and the second valve are both closed, so that the main exhaust pipeline is closed.

As a further improved technical solution of the present invention, the whole body formed by the first valve and the second valve and the bypass valve are linkage valves, wherein when the first valve and the second valve are opened, the bypass valve is closed; the bypass valve is opened when the first and second valves are closed.

As a further improved technical scheme of the utility model, the tail gas aftertreatment system is still including installing the first differential pressure sensor at particle trap's both ends and installing the second differential pressure sensor at selective catalytic reduction agent's both ends, first differential pressure sensor and second differential pressure sensor all with control system links to each other.

As the utility model discloses further modified technical scheme, tail gas aftertreatment system is including installing preceding nitrogen oxygen sensor in selective catalytic reduction agent's entrance and installing the back nitrogen oxygen sensor in selective catalytic reduction agent's exit.

As a further improved technical solution of the present invention, the urea injection system includes a urea tank, is used for carrying the urea solution in the urea tank to the urea pump of the urea nozzle and to be located the urea tank with the filter between the urea pumps.

As a further improved technical scheme of the utility model, the tail gas aftertreatment system is including installing the first deashing valve of the bottom of particle trap, installing the second deashing valve of the bottom of selective catalytic reduction agent and installing the sewage valve of the bottom of blender.

As a technical scheme of the utility model further improved, tail gas aftertreatment system is including installing the backpressure sensor in particulate trap's the upper reaches, be located first valve with exhaust-gas flowmeter between the backpressure sensor and be located particulate trap with temperature sensor between the selective catalytic reduction agent, backpressure sensor, exhaust-gas flowmeter and temperature sensor all with control system links to each other.

As the utility model discloses further modified technical scheme, tail gas aftertreatment system is fixed.

Compared with the prior art, the utility model has the advantages that the soot blowing function is set, when the particle catcher and/or the selective catalytic reducing agent are blocked, the blockage is eliminated in a soot blowing mode; in addition, when soot blowing can not eliminate blockage, the packaging system is maintained by opening the bypass pipeline, and convenience in system maintenance is improved.

Drawings

Fig. 1 is a schematic view of the exhaust gas aftertreatment system of the present invention.

Detailed Description

Referring to fig. 1, the present invention discloses a tail gas post-treatment system, which includes an exhaust pipe 1, a packaging system 2 installed on the exhaust pipe 1, a urea injection system 3 for injecting urea droplets into the packaging system 2, and a control system 4 for controlling the tail gas post-treatment system. The utility model discloses an exhaust aftertreatment system mainly is applied to in the fixed equipment, for example removes dust, takes off the round pin to the waste gas of industrial grade or diesel engine test station.

The exhaust line 1 is stationary and comprises a primary exhaust line 11 and a bypass line 12. The packaging system 2 is mounted in the primary exhaust line 11. The primary exhaust line 11 is provided with a first valve 111 mounted upstream of the packaging system 2 and a second valve 112 mounted downstream of the packaging system 2. The bypass line 12 is provided with a bypass valve 121. The primary exhaust pipe 11 and the bypass pipe 12 can only be selectively connected, that is, when the primary exhaust pipe 11 is connected, both the first valve 111 and the second valve 112 are opened; the bypass valve 121 is closed, so that the bypass line 12 is closed; when the bypass pipeline 12 is conducted, the bypass valve 121 is opened; the first valve 111 and the second valve 112 are both closed, so that the primary exhaust line 11 is closed.

Preferably, the whole of the first valve 111 and the second valve 112 and the bypass valve 121 are linkage valves, wherein when the first valve 111 and the second valve 112 are opened, the bypass valve 121 is closed; when the first valve 111 and the second valve 112 are closed, the bypass valve 121 is opened. The arrangement is favorable for improving the safety of the system.

The packaging system 2 includes a particulate trap (e.g., diesel particulate trap, DPF)21, a Selective Catalytic Reduction (SCR)22 located downstream of the particulate trap 21, a mixer 23 mounted between the particulate trap 21 and the selective catalytic reduction 22, a first soot blowing valve 241 for connecting the particulate trap 21 to a gas source 29, and a second soot blowing valve 242 for connecting the selective catalytic reduction 22 to the gas source 29. The gas source 29 is a high pressure gas source to provide sufficient pressure for sootblowing. The exhaust aftertreatment system further comprises a first differential pressure sensor 211 mounted across the particulate trap 21 and a second differential pressure sensor 221 mounted across the selective catalytic reductant 22. The first differential pressure sensor 211 is configured to detect whether the particulate trap 21 is clogged, and the second differential pressure sensor 221 is configured to detect whether the selective catalytic reduction agent 22 is clogged. The first differential pressure sensor 211 and the second differential pressure sensor 221 are both connected to the control system 4. Preferably, the exhaust gas aftertreatment system includes a first ash removal valve installed at the bottom of the particulate trap 21, a second ash removal valve installed at the bottom of the selective catalytic reduction agent 22, and a sewage valve installed at the bottom of the mixer 23. The first ash removal valve may be used to clean ash blown out of the particle catcher 21, thereby improving convenience of maintenance. Similarly, the second ash removal valve may be used to clean the ash blown out of the selective catalytic reduction agent 22, thereby improving the convenience of maintenance. Preferably, a special maintenance window may be designed above the mixer 23, urea crystals on the mixer 23 may be periodically checked, and the urea crystals may also be cleaned with a high-pressure water gun; the sewage valve can discharge the sewage generated by cleaning the mixer 23.

Furthermore, the exhaust aftertreatment system comprises a front nitrogen oxide sensor 251 installed at the inlet of the selective catalytic reducer 22 and a rear nitrogen oxide sensor 252 installed at the outlet of the selective catalytic reducer 22. The exhaust aftertreatment system further comprises a backpressure sensor 261 mounted upstream of the particulate trap 21, an exhaust gas flow meter 262 located between the first valve 111 and the backpressure sensor 261, and a temperature sensor 263 located between the particulate trap 21 and the selective catalytic reduction agent 22.

The urea injection system 3 includes a urea tank 31, a urea nozzle 32, a urea pump 33 for delivering the urea solution in the urea tank 31 to the urea nozzle 32, and a filter 34 between the urea tank 31 and the urea pump 33. The urea nozzle 32 is mounted on the encapsulation system 2 and is used to spray urea droplets towards the mixer 23. The urea droplets are pyrolyzed and hydrolyzed at high temperature of the exhaust gas to generate ammonia gas, and the ammonia gas and the nitrogen oxide compound can chemically react on the surface of the Selective Catalytic Reduction (SCR)22 to perform denitration (i.e., reduce the concentration of the nitrogen oxide compound). In the illustrated embodiment of the present invention, the urea injection system 3 further includes a common rail 35, and the common rail 35 is connected between the urea pump 33 and the urea injection nozzle 32. By providing the common rail 35, the stability of the system pressure can be improved, which is advantageous for improving the injection accuracy of the urea injection nozzle 32. In the illustrated embodiment of the present invention, the urea nozzle 32 is a urea backflow cooling type nozzle, that is, urea that enters the urea nozzle 32 but is not injected into the encapsulation system 2 flows back into the common rail 35 from the new flow, and on the one hand, the urea nozzle 32 can be cooled; on the other hand, urea can be saved.

The control system 4 is provided with a control cabinet 41, wherein the first valve 111, the second valve 112, the bypass valve 121, the first soot blower valve 241, the second soot blower valve 242, the exhaust gas flowmeter 262, the above-mentioned various sensors and the urea injection system 3 are all connected with the control system 4. The control cabinet 41 is provided with a display screen and an alarm lamp to monitor and alarm all conditions.

Furthermore, the utility model discloses still relate to an aforementioned tail gas aftertreatment system's control method, this control method includes following step:

s1: in normal operation, the bypass valve 121 is closed, and the first valve 111 and the second valve 112 are opened, so that the exhaust gas firstly flows through the particulate trap 21 for dust removal and then flows through the selective catalytic reducing agent 22 for denitration;

s2: the control system 4 controls the amount of urea droplets injected by the urea injection system 3 into the package system 2 through the urea injection nozzle 32;

s3: when the particle trap 21 is clogged, the control system 4 opens the first soot blowing valve 241 to blow soot to the particle trap 21;

s4: when the selective catalytic reducer 22 is blocked, the control system 4 opens the second soot blowing valve 242 to soot-blow the selective catalytic reducer 22;

s5: when the soot blowing in step S3 and/or step S4 fails to reduce the back pressure to the set value, the control system 4 opens the bypass valve 121, closes the first valve 111 and the second valve 112, and allows the exhaust gas to flow out of the bypass pipeline 12;

s6: maintenance is performed on the packaging system 2.

Specifically, in step S2, the urea injection system 3 determines whether to be on or not, based on the value of the temperature sensor 263. The urea injection system 3 can calculate a required urea injection amount from the exhaust gas flow meter 262 and the front nox sensor 251 and perform precise control. The urea injection system 3 can perform closed-loop control based on the test data of the post-nox sensor 252 to correct the urea injection amount.

Preferably, prior to step S5, the control system 4 increases the exhaust gas temperature to regenerate the particulate trap 21 when soot blowing of the particulate trap 21 in step S3 still fails to reduce the backpressure to a set value.

Compared with the prior art, the utility model adopts the particle adsorption method aiming at the particles, has high purification efficiency and low cost, designs a special operation mode aiming at the defects of difficult regeneration, troublesome maintenance and the like of the adsorption method, and can effectively solve the problems of blockage and maintenance; meanwhile, the denitration is calculated according to the real-time working state of the fixed equipment, and closed-loop control is adopted, so that the problems of insufficient conversion efficiency or standard exceeding of the traditional SCR and crystallization or substandard emission caused by catalyst aging can be effectively solved; meanwhile, by designing the bypass pipeline 12, when equipment is maintained, tail gas can directly pass through the bypass pipeline 12 under certain specific working conditions, so that the packaging system 2 can be maintained under the condition that the tail gas aftertreatment system is not shut down.

The above embodiments are only used for illustrating the present invention and not for limiting the technical solutions described in the present invention, and the understanding of the present specification should be based on the technical personnel in the technical field, and although the present specification has described the present invention in detail with reference to the above embodiments, the skilled personnel in the art should understand that the technical personnel in the technical field can still modify or substitute the present invention, and all the technical solutions and modifications thereof that do not depart from the spirit and scope of the present invention should be covered within the scope of the claims of the present invention.

Claims

1. An exhaust aftertreatment system comprising an exhaust line, a package system mounted on the exhaust line, a urea injection system for injecting urea droplets into the package system, and a control system for controlling the exhaust aftertreatment system; the method is characterized in that: the exhaust pipeline comprises a main exhaust pipeline and a bypass pipeline, the packaging system is installed in the main exhaust pipeline, the main exhaust pipeline is provided with a first valve installed on the upstream of the packaging system and a second valve installed on the downstream of the packaging system, and the bypass pipeline is provided with a bypass valve; the packaging system comprises a particle trap, a selective catalytic reduction agent positioned at the downstream of the particle trap, a mixer arranged between the particle trap and the selective catalytic reduction agent, a first ash blowing valve used for connecting the particle trap with a gas source, and a second ash blowing valve used for connecting the selective catalytic reduction agent with the gas source; the urea injection system includes a urea nozzle mounted on the packaging system and configured to inject urea droplets toward the mixer; the first valve, the second valve, the bypass valve, the first soot blowing valve, the second soot blowing valve and the urea injection system are all connected with the control system.

2. The exhaust aftertreatment system of claim 1, wherein: when the main exhaust pipeline is communicated, the first valve and the second valve are both opened; the bypass valve is closed, thereby closing the bypass line;

3. The exhaust aftertreatment system of claim 2, wherein: the whole formed by the first valve and the second valve and the bypass valve are linkage valves, wherein when the first valve and the second valve are opened, the bypass valve is closed; the bypass valve is opened when the first and second valves are closed.

4. The exhaust aftertreatment system of claim 1, wherein: the exhaust gas aftertreatment system further comprises a first differential pressure sensor and a second differential pressure sensor, the first differential pressure sensor is installed at two ends of the particle trap, the second differential pressure sensor is installed at two ends of the selective catalytic reducing agent, and the first differential pressure sensor and the second differential pressure sensor are connected with the control system.

5. The exhaust aftertreatment system of claim 1, wherein: the exhaust aftertreatment system includes a front nitrogen-oxygen sensor mounted at an inlet of the selective catalytic reductant and a rear nitrogen-oxygen sensor mounted at an outlet of the selective catalytic reductant.

6. The exhaust aftertreatment system of claim 1, wherein: the urea injection system includes a urea tank, a urea pump to deliver urea solution in the urea tank to the urea nozzle, and a filter between the urea tank and the urea pump.

7. The exhaust aftertreatment system of claim 1, wherein: the tail gas aftertreatment system comprises a first ash removal valve arranged at the bottom of the particle trap, a second ash removal valve arranged at the bottom of the selective catalytic reducing agent, and a sewage valve arranged at the bottom of the mixer.

8. The exhaust aftertreatment system of claim 1, wherein: the exhaust aftertreatment system comprises a backpressure sensor arranged on the upstream of the particle trap, an exhaust gas flowmeter arranged between the first valve and the backpressure sensor, and a temperature sensor arranged between the particle trap and the selective catalytic reducing agent, wherein the backpressure sensor, the exhaust gas flowmeter and the temperature sensor are all connected with the control system.

9. The exhaust aftertreatment system of any one of claims 1 to 8, wherein: the exhaust aftertreatment system is stationary.