CN202832772U

CN202832772U - Selective catalytic reduction (SCR) denitration system for large engine

Info

Publication number: CN202832772U
Application number: CN201220199403XU
Authority: CN
Inventors: 樊高峰; 吴安舟; 樊坚强; 王林
Original assignee: Tenneco China Co Ltd
Current assignee: Tenneco China Co Ltd
Priority date: 2012-05-03
Filing date: 2012-05-03
Publication date: 2013-03-27
Anticipated expiration: 2022-05-03

Abstract

The utility model provides a selective catalytic reduction (SCR) denitration system for a large engine. According to the SCR denitration system for the large engine, an SCR bale is arranged between a turbocharger and an engine to effectively solve the problems that efficiency of the engine is affected and exhaust gas flowing into the SCR bale is too low in temperature because traditionally, after the SCR bale is arranged on the turbocharger, backpressure of the engine is too high. A specific scavenging air receiver of the large engine, especially a marine two-stroke engine, is utilized and part of air in the scavenging air receiver is directly led to the upper portion of the turbocharger in a bypassing mode to enable the air fuel ratio of air inflowing into an air cylinder of the engine to decrease. Thus, pressure of the air cylinder is reduced, oil burning is relatively insufficient, temperature of the exhaust gas is enabled to rise, and efficiency of denitration is greatly promoted.

Description

Big-block engine SCR denitrating system

Technical field

The utility model relates to a kind of engine exhaust system, particularly a kind of Exhaust Emission Control system of big-block engine.

Background technique

Some big-block engine, particularly marine engine, delivery temperature usually are lower than 280 ℃～400 ℃ of the higher temperature ranges of SCR catalyst activity, this just so that the NOx in the waste gas can not fully be transformed.Because the big-block engine fuel oil mostly is HFO, sulphur content is high simultaneously, and particulate matter is many in the waste gas that burning produces, and the SCR catalyzer is stopped up, and back pressure also increases.At present, the method that improves exhaust temperature is a lot, all be to adopt other heating equipment or thermal insulation apparatus that tail gas is heated or be incubated, for example publication number is the Chinese patent of CN101514651, be coated with one or more layers of heat insulating coating on the described engine exhaust tube wall, to reduce the exhaust gas heat loss, play heat insulation effect; Perhaps at the engine exhaust tube wall firing unit being set comes tail gas is carried out heat temperature raising, this invention is exactly by tail gas being heated etc., thereby keep exhaust temperature in the optimum response active temperature scope of SCR, so that the Applicable scope of SCR technology is wider.

Publication number is the Chinese patent of CN102121411A, and infrared heater edge is enclosed within catalytic converter suction port extending section, and engine cold-start stage E CU control infrared heater improves exhaust temperature and catalytic conversion efficiency; When temperature in the catalytic converter and pressure reduction reached certain limit, the opening and closing of ECU control infrared heater impelled unburned product and the gasification of complicated complex compound on the retention mass, alleviation catalytic converter stopping state.

Notification number is the method that the CN102022214A Chinese invention patent discloses the low emission of large diesel engine emission control realization large diesel engine, the technological scheme that the present invention takes is, realize method and the implementing apparatus of large diesel engine low emission by control row temperature, realize by means of row's temperature control unit of motor, and the row's temperature ECU (Electrical Control Unit) that comprises the following steps: (1) motor reads respectively from the tach signal of engine crankshaft sensor with from the load signal of accelerator pedal sensor; (2) if the judged result of step (1) control exhaust gas temperature; (3) except adopting VVA, electronic throttle, supplements cold etc. to regulate the delivery temperature, to take the Insulation of assisting to gas exhaust piping; (4) will be optimized combustion process simultaneously, improve the flexible adjustable injection control strategy of jet pressure, employing of fuel oil as far as possible, this invention is mainly used in the large diesel engine emission control.But, although this method is taking VVA, electronic throttle, supplements cold etc. to regulate outside the delivery temperatures, only can rely on and will take the Insulation of assisting to gas exhaust piping, and mechanism is very complicated.

The model utility content

Technical problem to be solved in the utility model provides a kind of big-block engine SCR denitrating system, it can utilize the system of motor own more effectively to regulate and improve the exhaust temperature of big-block engine, solve effectively that the SCR catalyzer stops up and traditional approach on SCR is positioned over the engine back pressure rising problem of bringing after the turbosupercharger.

To achieve these goals, the utility model provides a kind of big-block engine SCR denitrating system, comprising:

One is arranged on the SCR between motor and the turbosupercharger, and the inlet end of described SCR links to each other with the exhaust emission tube road of described motor by the downtake pipe road, and its outlet side links to each other with the turbine end entrance of described turbosupercharger by a second exhaust pipe road;

One is arranged on the exhaust gas bypass pipeline between turbosupercharger and the scavenging air box, makes Exhaust temperature rise thereby the portion gas in the described scavenging air box is discharged to the turbine end entrance of described turbosupercharger from described by-pass line with suction pressure and air fuel ratio in the minimizing cylinder; And

One is arranged on the first control valve on the described by-pass line, and described the first control valve can be controlled portion gas in the described scavenging air box is discharged to described turbosupercharger from described by-pass line turbine end entrance.

Further, described downtake pipe road is provided with one second control valve and is drained into described SCR with the waste gas of controlling described motor.

Further again, between the exhaust emission tube road of described motor and described turbosupercharger, be provided with one the 3rd exhaust duct so that the waste gas of motor directly is discharged to described turbosupercharger.

Further, but described the 3rd exhaust duct is provided with waste gas that a control engine discharges to the 3rd valve of the turbine end entrance of described turbosupercharger.

Further again, be provided with a heating equipment so that the waste gas before described motor is drained into described SCR heats at the inlet end of described SCR.

The utility model provides a kind of big-block engine SCR denitrating system further to comprise one and is used for differential pressure transducer that pressure reduction before and after the SCR7 is measured, and when differential pressure rose too high before and after detecting the SCR catalyzer, heating equipment was regenerated to catalyzer automatically.

Method and the system thereof of the big-block engine SCR denitration that the utility model provides, because the large bag of SCR is placed between turbosupercharger and the motor in order to effectively avoid the engine back pressure rising and improve the exhaust gas temperature that enters into SCR, and utilize the particularly distinctive scavenging air box of two stroke engine peculiar to vessel of big-block engine, the direct bypass of part waste gas in the scavenging air box is extremely arrived the turbosupercharger upstream so that the air inlet air fuel ratio in the cylinder reduces, cylinder is pressed and is reduced, oil inflame is insufficient, so that Exhaust temperature rise improves the efficient of little denitration greatly.

Description of drawings

Fig. 1 is an embodiment's of big-block engine SCR denitrating system of the present utility model schematic representation.

Fig. 2 is an embodiment's the schematic representation of the central unit of big-block engine SCR denitrating system of the present utility model.

Fig. 3 is the workflow diagram of the central unit of Fig. 2.

Embodiment

Below in conjunction with accompanying drawing, embodiment of the present utility model is described further.

The utility model provides a kind of big-block engine SCR denitrating system to comprise that one is arranged on the SCR7 between motor 1 and the turbosupercharger 9, the inlet end of SCR7 links to each other with the exhaust emission tube road 3 of motor by downtake pipe road 51, and its outlet side links to each other with the turbine end entrance of turbosupercharger 9 by second exhaust pipe road 81.The waste gas that motor 1 is discharged enters waste gas through gas exhaust manifold 2 and discharges the direction of arrow that main pipe 3(sees E among the figure).

The gas of the scavenging air box 11 of two stroke big-block engine 1 can flow in the cylinder of motor 1 (seeing the D direction of arrow among the figure).By between turbosupercharger 9 and scavenging air box 11, being provided with by-pass line 201, big-block engine SCR denitrating system of the present utility model can be discharged to from by-pass line 201 the turbine end entrance of turbosupercharger 9 by the portion gas in the scavenging air box 11, raises thereby can reduce like this exhaust gas temperature that suction pressure in motor 1 cylinder and air fuel ratio make its discharge.One is arranged on the first control valve 12 on the by-pass line 201, the first control valve 12 can adopt common gas valve, electronic dish valve for example, it can control portion gas in the scavenging air box 11 directly is discharged to turbosupercharger 9 from by-pass line 201 turbine end entrance.

Also be provided with the second control valve 5 on downtake pipe road 51, the waste gas that it can control engine 1 is drained into SCR7.The second control valve 5 can adopt common gas valve, for example solenoid valve.Between the exhaust emission tube road 3 of motor 1 and turbosupercharger 9, also be provided with the 3rd exhaust duct 41 so that the waste gas of motor 1 can directly be discharged to the turbine end entrance of turbosupercharger 9.But directly be drained into the 3rd control valve 4 of the turbine end entrance of turbosupercharger 9 at the waste gas that the 3rd exhaust duct 41 is provided with a control engine 1.On the inlet end of SCR7, also be provided with a heating equipment 6 and further heat or catalyzer is regenerated in order to motor 1 is drained into waste gas before the described SCR7.The pipeline that links to each other with turbosupercharger 9 at SCR7 is provided with the 4th control valve 8, can adopt common gas valve, solenoid valve for example, and it can prevent gas backflow.In addition, the system of the big-block engine SCR denitration that provides of the utility model also further is provided with differential pressure transducer (the not shown in the figures meaning out) and is used for pressure reduction before and after the SCR7 is measured.This differential pressure transducer comprises two probes, and one is positioned at the SCR7 suction port, and another probe is positioned at the SCR7 air outlet, and the pressure reduction of SCR7 suction port and air outlet is measured.

Exhaust gas denitration for further control engine 1, big-block engine SCR denitrating system of the present utility model also is provided with central unit (CPU), this central unit can according to detecting from the temperature of the waste gas of motor 1 discharge, be controlled the work (referring to Fig. 2) of the above-mentioned all parts of big-block engine SCR denitrating system of the present utility model.The temperature that detects the waste gas that motor 1 discharges is that the pipeline at the front end of heating equipment 6 arranges a temperature detection sensor (not illustrating among Fig. 1), and this temperature detection sensor links to each other with above-mentioned central unit.Referring to Fig. 2, concrete steps are as follows:

1, when ship running in non-emission control zone or SCR7 system when breaking down (serious as stopping up), central unit sends control signal the second control valve 5, the 4th control valve 8 and the first control valve 12 is closed, it is open-minded with the 3rd control valve 4 to send simultaneously control signal, this moment, exhaust emission tube road 3 waste gas of discharging of motor 1 directly flowed to H direction arrow the turbosupercharger 9(figure from the 3rd exhaust duct 41), in fact, in this case, discardedly do not carry out denitration and process.

2, when ship running in emission control when zone, it is open-minded with the second control valve 5, the 4th control valve 8 that central unit sends control signal, and the 3rd control valve 4 closed, the waste gas of exhaust emission tube road 3 discharges of motor 1 can enter by downtake pipe road 51 (seeing the A direction arrow among Fig. 1) SCR7 at this moment, urea-spray control unit control urea nozzle 13 is sprayed urea, carry out denitration and process, simultaneously:

When the delivery temperature that (1) detects motor when the said temperature detecting sensor was enough high, central unit sent control signal control heating equipment 6 and does not work, and central unit sends control signal to the first control valve 12, and it is closed.

(2) when delivery temperature not high enough: the said temperature detecting sensor detects the delivery temperature of motor when not high enough, central unit sends control signal and opens the first control valve 12, like this, portion gas in the scavenging air box 11 directly is discharged to the turbine end entrance of turbosupercharger 9 from by-pass line 201, and the partial-air admission of motor 11 is by bypass (seeing F direction arrow among the figure) like this, and air fuel ratio is lowered, cylinder is pressed and is reduced, oil inflame is insufficient, Exhaust temperature rise, if:

1) when this moment temperature enough up to the working efficiency of SCR7, central unit sends control signal control heating equipment 6 and does not work;

2) when temperature this moment not high enough working efficiency to satisfying SCR7 still, central unit sends 6 work of control signal control heating equipment, and the waste gas that flows to SCR7 is heated, and can also regenerate to the SCR catalyzer simultaneously.

(3) raise when excessive when above-mentioned differential pressure transducer detects before and after the SCR7 pressure reduction, central unit sends 6 work of control signal control heating unit, the waste gas that flows into SCR7 is heated, thereby SCR7 is regenerated, and further eliminates and stops up.

By top description, can find out, the method of the big-block engine SCR denitration that the utility model provides and system thereof are owing to SCR7 is placed between turbosupercharger 9 and the motor 1 in order to effectively avoid traditional backpressure rising problem to improve simultaneously the exhaust gas temperature that flows into SCR, and utilize the particularly distinctive scavenging air box 11 of two-stroke marine engine peculiar to vessel of big-block engine, by the portion gas in the scavenging air box 11 is directly discharged from the upstream of turbosupercharger 9 so that the air inlet air fuel ratio in the cylinder of motor 1 reduce, cylinder is pressed and is reduced, oil inflame is insufficient, so that Exhaust temperature rise, greatly improve the efficient of little denitration, this heating equipment that is placed on before the SCR has guaranteed to flow into the exhaust gas temperature of the large bag of SCR and can regenerate to the SCR catalyzer especially, avoids stopping up.

More than show and described basic principle of the present utility model and major character and advantage of the present utility model.The technician of the industry should understand; the utility model is not restricted to the described embodiments; that describes in above-described embodiment and the specification just illustrates principle of the present utility model; under the prerequisite that does not break away from the utility model spirit and scope; the utility model also has various adjustment, changes and improvements, and these are adjusted, changes and improvements all should fall in claimed the utility model scope in the situation that does not depart from basic principle of the present utility model and major character.The claimed scope of the utility model is limited by the accompanying claims

Claims

1. big-block engine SCR denitrating system is characterized in that it comprises:

2. big-block engine SCR denitrating system as claimed in claim 1 is characterized in that, described downtake pipe road is provided with one second control valve and is drained into described SCR with the waste gas of controlling described motor.

3. big-block engine SCR denitrating system as claimed in claim 1, it is characterized in that, further again, between the exhaust emission tube road of described motor and described turbosupercharger, be provided with one the 3rd exhaust duct so that the waste gas of motor directly is discharged to described turbosupercharger.

4. big-block engine SCR denitrating system as claimed in claim 1 is characterized in that, but described the 3rd exhaust duct is provided with the waste gas of control engine discharge to the 3rd valve of the turbine end entrance of described turbosupercharger.

5. big-block engine SCR denitrating system as claimed in claim 1 is characterized in that, is provided with a heating equipment so that the waste gas before described motor is drained into described SCR heats and the SCR catalyzer is regenerated at the inlet end of described SCR.

6. such as the arbitrary described big-block engine SCR denitrating system of claim 1-5, it is characterized in that, also further comprise one and be used for differential pressure transducer that pressure reduction before and after the described SCR is measured; When the differential pressure before and after detecting described SCR rose too high, the described heating equipment before the described SCR heated regenerated catalyst to waste gas.