Plasma system of natural gas engine

Technical Field

The invention relates to a natural gas engine field, particularly relates to a natural gas engine of the plasma system.

Background Art

As countries increasingly stringent emission regulations, the engine emission control to meet increasingly high requirements. In order to make the natural gas engine to meet European six and the above emission level, at the present stage in the route all emission control technology, equivalent combustion with EGR (exhaust gas recirculation system) and TWC (three-way catalytic converter) combined is considered as the mainstream technology. In this technique, is reduced as much as possible of the NOx in the exhaust gas (nitrogen oxide), part of the exhaust gas introduced into the intake system, and the fuel gas is mixed with the air fed into the cylinder combustion, because of the inert gas such as carbon dioxide in the gas mixture increases, caused by the combustion in the cylinder speed slacken, while at the same time mixed gas specific heat capacity also increased, leading to the in-cylinder combustion temperature is decreased, thereby suppressing the generation of NOx.

In general EGR rate can not be more than 20%, but for adopting the equivalent combustion engine, heat load is high, the increase of the EGR rate can significantly reduce the heat load of the engine, so that the need to increase the EGR rate. But EGR rate increases in the air intake system after the introduction of the exhaust gas, each cylinder of the decline in the stability of the combustion, the ignition of the engine will also be more difficult, the need to increase the ignition energy, but will make the ignition reliability of the system decrease, and as the EGR rate (the introduction of the exhaust gas with the fresh air-fuel mixture ratio) rise, will increase the gas consumption of the engine, the power of the engine, HC (hydrocarbon) emissions rise, at the same time adopts the TWC processing in the exhaust gas of CH4, NOx and CO, must ensure that the TWC in the vicinity of the stoichiometric ratio in the narrow section can be three exhaust pollutant conversion efficiency at the same time the highest, otherwise, there will be a deterioration in emission situation, three exhaust pollutant conversion efficiency is difficult to control.

The publicizes in background of technical information only of the present invention aimed at increasing the overall background understanding, but should not be considered as recognition or any form implies that the information forms has been general technical personnel in this field the known existing technology.

Content of the invention

The purpose of this invention is to provide a simple and reasonable structure of natural gas engine of the plasma system, the natural gas engine of the plasma system can improve the engine cylinder after the exhaust introduced in the problem of the decline of the stability of the combustion, can shorten the ignition delay, accelerate in-cylinder flame propagation speed, widen the knock boundary, thereby improving the combustion efficiency, reduce HC emissions, at the same time, also can reduce the ignition energy of the ignition system, improve the reliability of the ignition system. In addition, since the plasma addition, can improve the activity of the catalyst, reducing the CH4, NOx and CO pollutants such ignition temperature, the maximum combustion temperature and the combustion temperature, thereby improving the conversion efficiency of the three pollutants.

To achieve the above object, the present invention provides a natural gas engine of the plasma system, the natural gas engine of the plasma system includes: an air inlet pipe; the exhaust pipe; EGR tube, one end of which is communicated with the exhaust pipe, the other end to a communicated with the inlet pipe, the EGR pipe is provided with a EGR valve, the EGR regulating valve with the ECU control connection; the plasma generator, which is arranged in the exhaust pipe, and located in said EGR tube communicated with the exhaust pipe upstream from the position of; and catalytic converters, which is arranged in the exhaust pipe, and located in said EGR tube communicated with the exhaust pipe downstream of the position.

Preferably, in above technical scheme, the plasma generator through the plasma power supply connected with the power supply.

Preferably, in above technical scheme, the plasma generator through the gas discharge method to generate plasma.

Preferably, in above technical scheme, the plasma generator for tube barrel type, line type, faller, filling bed type, has self peace plate type.

Compared with the prior art, this invention has the following effects: the natural gas engine of the plasma system can improve the engine cylinder after the exhaust introduced in the problem of the decline of the stability of the combustion, can shorten the ignition delay, accelerate in-cylinder flame propagation speed, widen the knock boundary, thereby improving the combustion efficiency, reduce HC emissions, at the same time, also can reduce the ignition system of the ignition energy, improve the reliability of the ignition system. In addition, since the plasma addition, can improve the activity of the catalyst, reducing the CH4, NOx and CO pollutants such ignition temperature, the maximum combustion temperature and the combustion temperature, thereby improving the conversion efficiency of the three pollutants.

Description of drawings

Figure 1 is the structure diagram of the invention natural gas engine of the plasma system.

Mode of execution

The Figure below, the present invention relates to the specific embodiment described in detail, but it should be understood that the scope of protection of the invention is not limited by the specific embodiment.

Unless otherwise expressly indicated, otherwise throughout the specification and in the claims, the term "comprises" or "comprising" or conversion such as "comprising" and the like will be understood to include the statements of the component or components, and does not exclude other elements or other components.

As shown in Figure 1, according to the present invention embodiment of natural gas engine of the plasma system in generating a plasma in the engine exhaust gas through the EGR system and a part of the introduction of the air intake system to participate in the combustion. And in in the engine exhaust gas to generate plasma and catalytic device mode of combining processing in the exhaust gas of the pollutants. The plasma system of the specific structure comprises: an air inlet pipe 1, EGR pipe 2, EGR regulating valve 3, plasma generator 5, plasma power supply 6 and the catalyst 7. An air inlet pipe 1 in the gas mixture of the air and the fuel gas with the EGR pipe 2 contained in the EGR gas mixing after the plasma of, a spark plug into the cylinder 4 to ignite the combustion, combustion after the completion of the exhaust gas enters into the plasma generator 5 to generate plasma, containing plasma be re-introduced into a part of the exhaust gas to the intake system involved in combustion, and the other part through the catalytic converter 7 is discharged into the atmosphere in the environment directly after, in the EGR system, EGR3 regulating valve by the ECU control its opening, is introduced into the air intake system so that precise control of the displacement of the size of the size of the EGR rate. The natural gas engine of the plasma system can improve the engine cylinder after the exhaust introduced in the problem of the decline of the stability of the combustion, can shorten the ignition delay, accelerate in-cylinder flame propagation speed, widen the knock boundary, thereby improving the combustion efficiency, reduce HC emissions, at the same time, also can reduce the ignition system of the ignition energy, improve the reliability of the ignition system. In addition, since the plasma addition, can improve the activity of the catalyst, reducing the CH4, NOx and CO pollutants such ignition temperature, the maximum combustion temperature and the combustion temperature, thereby improving the conversion efficiency of the three pollutants.

Specifically, EGR tube 2 and one end of the exhaust pipe of the engine 8 is connected, the other end of the air inlet pipe 1 connected, part of the exhaust gas introduced into the intake system, and the fuel gas is mixed with the air fed into the cylinder combustion, because of the inert gas such as carbon dioxide in the gas mixture increases, caused by the combustion in the cylinder speed slacken, while at the same time mixed gas specific heat capacity also increased, leading to the reduction of the temperature of the in-cylinder combustion, thereby suppressing the generation of NOx. In the EGR system, EGR control valve 3 is arranged in the EGR pipe 2 on, and connected with the ECU control, by the ECU to control its opening degree, in order to accurately control the introduction of air intake system the air displacement of the size of the size of the EGR rate. The EGR exhaust gas recirculation (Exhaust Gas Recirculation), in the internal combustion engine after the combustion of the separated part of the exhaust gas, and introduced into the intake side of the re-combustion of the technical (means or method). The main objective of reducing oxides of nitrogen in the exhaust gas (NOx).

The gas mixture of the air and fuel gas through the inlet pipe 1 enters the cylinder, EGR pipe 2 with an air inlet pipe 1 connected to the back, the air inlet pipe 1 in the gas mixture of the air and the fuel gas with the EGR pipe 2 after being mixed in the EGR gas, a spark plug into the cylinder 4 to ignite the combustion.

The plasma generator 5 is arranged in the exhaust pipe of the engine 8 on, and located in the EGR pipe 2 communicated with the exhaust pipe upstream from the position of. The plasma generator 5 through the plasma power supply 6 power supply, after the completion of the combustion of the exhaust gas enters into the plasma generator 5 through the gas discharge method to generate plasma, such as glow discharge, radio frequency discharge, microwave discharge, corona discharge and dielectric barrier discharge, discharge after the completion of the plasma generator 5 is generated in the strong oxidation of NO2, O, OH, O3, of the metastable state of a nitrogen atom, an oxygen atom of the freedom of active ion, in the air intake system of the main gas component is CH4, N2, O2 and H2O and the like, to contain a plasma of a part of the exhaust gas to be re-introduced into the air intake system to participate in the combustion, is introduced into the exhaust gas in addition to the N2, CO2, H2O, O2, THC, NOx and CO outer, also a large number of chemical activity of formula O atom, H atom, OH-based and, after mixing with the combustible gas mixture in the engine cylinder, these chemical active group can damage the combustion system balance, tempts oxidation chain reaction, thereby shortening the ignition delay, accelerating the burning speed, so as to inhibit the production of detonation. In the presence of a reactive group can improve the combustion efficiency, thereby reducing the generation of pollutants THC; on the other hand, can greatly increase the EGR rate (more than 20%), a breakthrough of the existing technical conditions EGR rate-limiting, so that the NOx is reduced and the center of the engine the magnitude of, the knock boundary is wider, the reliability of the engine is better.

Preferably, the plasma generator 5 may take the form of a plurality of, in general can be barrel - type, line - type, needle - plate type, filling bed type, line - plate type, plate type and the like.

The catalyst 7 is arranged in the exhaust pipe of the engine, and located in the EGR pipe 2 communicated with the exhaust pipe downstream of the position. Containing plasma of another part of the exhaust gas through the catalytic converter 7 is discharged into the atmosphere in the environment directly after, the use of exhaust gas of the plasma in the activity of the catalyst can be improved, and the ignition temperature of exhaust pollutants, the maximum combustion temperature and the combustion temperature will be greatly reduced, thereby improving the conversion efficiency of the catalyst in the pollutants.

From the foregoing, the natural gas engine of the plasma system can improve the engine cylinder after the exhaust introduced in the problem of the decline of the stability of the combustion, can shorten the ignition delay, accelerate in-cylinder flame propagation speed, widen the knock boundary, thereby improving the combustion efficiency, reduce HC emissions, at the same time, also can reduce the ignition system of the ignition energy, improve the reliability of the ignition system. In addition, since the plasma addition, can improve the activity of the catalyst, reducing the CH4, NOx and CO pollutants such ignition temperature, the maximum combustion temperature and the combustion temperature, thereby improving the conversion efficiency of the three pollutants.

The present invention of the aforesaid specific illustrative embodiment is described in order to explain the purpose of and examples. These are described and I do not wish to be limited to the disclosed invention precise form, and it is clear that, according to the above teaching, many changes and changes can be carried out. The illustrative embodiment can be chosen and described to explain the invention the purpose of the specific principle and its practical application, thereby enabling the field of the technical staff can realize and utilize this invention the various illustrative embodiments and various different selection and change. The scope of the invention is intended by the claims and its equivalents defined.