阅读说明：本技术 废气-燃料催化重整与催化剂再生的天然气发动机试验系统及控制方法 (Natural gas engine test system for catalytic reforming of exhaust gas-fuel and regeneration of catalyst and control method ) 是由 李格升 龙焱祥 张尊华 吴仁民 钱航 于 2019-08-29 设计创作，主要内容包括：本发明公开了一种废气-燃料催化重整与催化剂再生的天然气发动机试验系统及控制方法,利用部分废气余热进行废气重整制氢反应,将重整产生的富氢气混合气通入发动机中探究重整器工作参数对发动机性能与排放的影响规律,实现重整器与发动机性能匹配。同时,针对重整器内催化剂失活问题,能在线进行催化剂还原；此外,台架能在实验结束后将N<Sub>2</Sub>充入重整器中,形成惰性氛围保护催化剂,避免降温过程重整器内部残留的废气氧化造成催化剂失活的问题。(The invention discloses a natural gas engine test system for catalytic reforming of waste gas-fuel and regeneration of a catalyst and a control method thereof. Meanwhile, aiming at the problem of catalyst deactivation in the reformer, the catalyst can be reduced on line; in addition, N2 can be filled into the reformer by the rack after the experiment is finished, an inert atmosphere is formed to protect the catalyst, and the problem that the catalyst is inactivated due to oxidation of residual waste gas in the reformer in the temperature reduction process is solved.)

1. A natural gas engine test system for catalytic reforming of exhaust gas-fuel and regeneration of catalyst is characterized in that: comprises a reformer (1), an engine (2), a mixer (9), an intercooler (8), a three-way pipe (10), a gas tank (3), a flow regulating valve (4), an H2 tank (11) and an N2 tank (12); a reaction gas inlet (1A) of the reformer (1) is connected with an engine exhaust pipe (14) through a first exhaust branch pipe (21A), an exhaust gas inlet (1B) of the reformer (1) is connected with the engine exhaust pipe through a second exhaust branch pipe (21B), a reformer gas outlet (1C) of the reformer (1) is connected with an inlet a of a three-way pipe (10), an outlet B of the three-way pipe (10) is sequentially connected with an intercooler (8) and a mixer (9) in series through a reformed gas bypass pipe (16), and the mixer (9) is connected with a gas inlet of the engine (2) through an engine gas inlet pipe (13); the waste gas outlet (1D) of the reformer (1) is connected with the atmosphere through an atmosphere pipeline (15), and the outlet c of the three-way pipe (10) is communicated with the atmosphere pipeline (15) through an atmosphere valve (7); first exhaust branch pipe (21A) link to each other with flow control valves (4) through gas mixture supply pipe (18), gas pitcher (3) link to each other with flow control valves (4) through fuel pipeline (17), H2 jar (11) link to each other with flow control valves (4) through H2 pipeline (19), N2 jar (12) are through N2 pipeline (20) and flow control valves (4).

2. The natural gas engine test system for catalytic reforming of exhaust gas-fuel and regeneration of catalyst according to claim 1, wherein: the first exhaust branch pipe (21A) is provided with a REGR front end valve (5).

3. The natural gas engine test system for catalytic reforming of exhaust gas-fuel and regeneration of catalyst according to claim 1, wherein: and a REGR rear end valve (6) is arranged on the reformed gas bypass pipe (16).

4. The natural gas engine test system for catalytic reforming of exhaust gas-fuel and regeneration of catalyst according to claim 1, wherein: an atmosphere valve (7) is arranged on the atmosphere pipeline (15).

5. the natural gas engine test system for catalytic reforming of exhaust gas-fuel and regeneration of catalyst according to claim 1, wherein: the gas pitcher (3) link to each other through fuel pipeline (17) and the first automatically controlled butterfly valve of flow control valves (4), H2 jar (11) link to each other through the second automatically controlled butterfly valve of H2 pipeline (19) with flow control valves (4), N2 jar (12) link to each other through the third automatically controlled butterfly valve of N2 pipeline (20) with flow control valves (4).

6. a method of controlling a natural gas engine test system for catalytic reforming of exhaust gas-fuel and regeneration of catalyst according to claim 1, characterized by:

When the catalytic reforming test of the exhaust gas fuel is carried out, the specific process is as follows:

Outputting a voltage signal corresponding to the valve opening degree of 0 degrees to close a REGR rear end valve (6), and outputting a voltage signal corresponding to the valve opening degree of 90 degrees to open an atmospheric valve (7); a first electric control butterfly valve of a voltage signal regulating flow regulating valve group (4) with the opening of the output valve not larger than 5 degrees; outputting a voltage signal corresponding to the valve opening degree of 90 degrees to open a REGR rear end valve (6), and simultaneously outputting a voltage signal corresponding to the valve opening degree of 0 degrees to close an atmospheric valve (7); outputting a voltage signal corresponding to the opening degree of the valve, adjusting a REGR front end valve (5) and a flow adjusting valve group (4) to change the flow of the waste gas and the flow of the natural gas entering a reforming pipe of the reformer by a first electric control butterfly valve, and acquiring the performance influence of the space velocity and the carbon-oxygen ratio in the reformer on the LNG engine;

when the exhaust-fuel catalytic reforming test is finished, the specific process is as follows:

After the LNG engine is closed, outputting a voltage signal corresponding to the valve opening degree of 0 degrees to close a REGR front end valve (5) and a REGR rear end valve (6); a third electric control butterfly valve of the voltage signal regulating flow regulating valve group (4) corresponding to the output valve opening degree of 15-25 degrees continuously introduces N2 airflow into a reformer reaction gas inlet (1A); after a period of time, a voltage signal corresponding to the valve opening degree of 0 degrees is output to close a third electric control butterfly valve and an atmospheric valve (7) of the flow regulating valve group (4), so that a closed inert gas atmosphere is formed, and the activity of the catalyst is prevented from being reduced due to oxidation in the cooling process.

7. The control method of a natural gas engine test system for catalytic reforming of exhaust gas-fuel and regeneration of catalyst according to claim 6, characterized in that: the specific process of catalyst reduction is as follows:

after the LNG engine is started, the LNG engine is kept in normal working condition operation, and a voltage signal corresponding to the opening degree of the valve of 0 degree is output to close the REGR front end valve (5) and the REGR rear end valve (6); outputting a voltage signal corresponding to the valve opening degree of 90 degrees to open an atmospheric valve (7); a second electric control butterfly valve and a third electric control butterfly valve of the voltage signal regulating flow regulating valve group (4) corresponding to the valve opening degrees of 15-25 degrees and 60-80 degrees are respectively output, and a mixture of N2 and H2 is continuously introduced into a reaction gas inlet (1A) of the reformer; after the engine runs for a period of time, the engine is closed, voltage signals with the valve opening degree of 0 degree and 15-25 degrees are respectively output, a second electric control butterfly valve in the flow regulating valve group is closed, a third electric control butterfly valve is regulated, and N2 is continuously introduced into a reaction gas inlet (1A) of the reformer; after a period of time, outputting a voltage signal corresponding to the valve opening degree of 0 degrees to close a third electric control butterfly valve and an atmospheric valve (7) in the flow regulating valve group (4) to form a closed inert gas atmosphere.

Technical Field

the invention relates to the technical field of natural gas engine tests, in particular to a natural gas engine test system for catalytic reforming of exhaust gas-fuel and regeneration of a catalyst and a control method.

Background

the exhaust-fuel reforming technology utilizes the waste heat of high-temperature exhaust gas of an engine to catalyze a small amount of fuel and part of the exhaust gas to generate hydrogen-rich reformed gas through an exhaust-fuel reformer. The reformed gas contains H2, CH4, CO and the like, and can improve the combustion of the engine and reduce the emission of pollutants when being introduced into the engine.

most of the catalysts used by the existing exhaust gas fuel reformers are Ni-Rh/Al2O3 and the like, and in an actual bench test, after a long-time catalytic reforming test, the phenomena of catalyst sintering, carbon deposition, active site oxidation and the like exist, so that the activity of the catalyst is reduced. Meanwhile, after the bench test is finished, fuel is not added into the reformer at this time, the catalyst still has high activity in the temperature reduction process, and is easily oxidized by oxygen remained in the waste gas in the reformer, so that the activity of the catalyst is further reduced. In addition, improper operation of the reforming test process, such as an insufficient fuel supply resulting in too low a carbon to oxygen ratio, can also cause catalyst deactivation problems.

When the catalyst activity is reduced too much, the catalyst in the reformer needs to be replaced at this time to continue the test. Since the catalyst is usually installed in a tube bundle inside the reformer, it is not easily removed and replaced; on one hand, the reformer is usually in a high-temperature state when working, the temperature of the catalyst on the surface and in the reactor is very high, and at the moment, the catalyst needs to be taken out after being cooled for a long time, and the catalyst is replaced by a new catalyst, which wastes time and labor; on the other hand, the prepared reforming catalyst is generally expensive, and the cost required for replacing the catalyst is high.

Disclosure of Invention

The invention aims to provide a natural gas engine test system and a control method for exhaust gas-fuel catalytic reforming and catalyst regeneration, which can regenerate a catalyst, recycle the catalyst and shorten the time required by test research aiming at the defects of the technology.

In order to achieve the aim, the natural gas engine test system for catalytic reforming of exhaust gas-fuel and regeneration of catalyst comprises a reformer, an engine, a mixer, an intercooler, a three-way pipe, a gas tank, a flow regulating valve, an H2 tank and an N2 tank; the reaction gas inlet of the reformer is connected with an engine exhaust pipe through a first exhaust branch pipe, the waste gas inlet of the reformer is connected with the engine exhaust pipe through a second exhaust branch pipe, the reformer gas outlet of the reformer is connected with the inlet a of a three-way pipe, the outlet b of the three-way pipe is sequentially connected with an intercooler and a mixer in series through a reformed gas bypass pipe, and the mixer is connected with the gas inlet of the engine through an engine gas inlet pipe; the waste gas outlet of the reformer is connected with the atmosphere through an atmosphere pipeline, and the outlet c of the three-way pipe is communicated with the atmosphere pipeline through an atmosphere valve; first exhaust branch pipe passes through the gas mixture supply pipe and links to each other with flow control valves, the gas pitcher passes through fuel line and links to each other with flow control valves, the H2 jar passes through the H2 pipeline and links to each other with flow control valves, the N2 jar passes through N2 pipeline and flow control valves.

Further, a REGR front end valve is arranged on the first exhaust branch pipe.

furthermore, a REGR rear-end valve is arranged on the reformed gas bypass pipe.

Further, an atmosphere valve is arranged on the atmosphere pipeline.

further, the gas pitcher passes through the fuel pipeline and links to each other with the first automatically controlled butterfly valve of flow control valves, the H2 jar passes through the H2 pipeline and links to each other with the second automatically controlled butterfly valve of flow control valves, the N2 jar passes through the N2 pipeline and links to each other with the third automatically controlled butterfly valve of flow control valves.

A control method of the natural gas engine test system for catalytic reforming of exhaust gas-fuel and regeneration of the catalyst is also provided.

When the catalytic reforming test of the exhaust gas fuel is carried out, the specific process is as follows:

Outputting a voltage signal corresponding to the valve opening degree of 0 degrees to close a REGR rear end valve, and outputting a voltage signal corresponding to the valve opening degree of 90 degrees to open an atmospheric valve; a first electric control butterfly valve of the voltage signal regulating flow regulating valve group, the opening of which is not more than 5 degrees, is output; outputting a voltage signal corresponding to the valve opening degree of 90 degrees to open a REGR rear end valve, and simultaneously outputting a voltage signal corresponding to the valve opening degree of 0 degrees to close an atmospheric valve; outputting a voltage signal corresponding to the opening degree of the valve, adjusting a REGR front end valve and a first electric control butterfly valve of a flow adjusting valve group to change the flow rate of the exhaust gas entering a reforming pipe of the reformer and the flow rate of the natural gas, and obtaining the influence of the space velocity and the carbon-oxygen ratio in the reformer on the performance of the LNG engine;

when the exhaust-fuel catalytic reforming test is finished, the specific process is as follows:

After the LNG engine is closed, outputting a voltage signal corresponding to the opening degree of the valve of 0 degree to close the REGR front end valve and the REGR rear end valve; a third electric control butterfly valve of the voltage signal regulating flow regulating valve group corresponding to the output valve opening degree of 15-25 degrees continuously introduces N2 airflow to a reformer reaction gas inlet; after a period of time, a voltage signal corresponding to the opening degree of the output valve of 0 degree closes a third electric control butterfly valve and an atmospheric valve of the flow regulating valve group, and a closed inert gas atmosphere is formed to avoid the reduction of activity caused by oxidation in the catalyst cooling process.

Further, the specific process of catalyst reduction is as follows:

After starting the LNG engine, the LNG engine is maintained to operate under a normal working condition, and the exhaust temperature is stabilized at 400 ℃; outputting a voltage signal corresponding to the valve opening degree of 0 degrees to close a REGR front end valve and a REGR rear end valve; outputting a voltage signal corresponding to the valve opening degree of 90 degrees to open an atmospheric valve; a second electric control butterfly valve and a third electric control butterfly valve of the voltage signal regulating flow regulating valve group corresponding to the valve opening degrees of 15-25 degrees and 60-80 degrees are respectively output, and a mixture of H2 and N2 is continuously introduced into a reaction gas inlet of the reformer; after the engine runs for a period of time, the engine is closed, voltage signals with the valve opening degree of 0 degree and 15-25 degrees are respectively output, a second electric control butterfly valve in the flow regulating valve group is closed, a third electric control butterfly valve is regulated, and N2 is continuously introduced into a reaction gas inlet of the reformer; after a period of time, outputting a voltage signal corresponding to the valve opening degree of 0 degrees to close a third electric control butterfly valve and an atmospheric valve in the flow regulating valve group to form a closed inert gas atmosphere.

Compared with the prior art, the invention has the following beneficial effects: the invention utilizes partial waste gas afterheat to carry out the hydrogen production reaction by reforming the waste gas, introduces hydrogen-rich gas mixture generated by reforming into the engine, explores the rule of the influence of the working parameters of the reformer on the performance and the emission of the engine, and realizes the matching of the performance of the reformer and the engine. Meanwhile, aiming at the problem of catalyst deactivation in the reformer, the catalyst can be reduced on line; in addition, N2 can be filled into the reformer by the rack after the experiment is finished, an inert atmosphere is formed to protect the catalyst, and the problem that the catalyst is inactivated due to oxidation of residual waste gas in the reformer in the temperature reduction process is solved.

drawings

FIG. 1 is a block flow diagram of a natural gas engine test system for catalytic reforming of exhaust gas-fuel and regeneration of catalyst in accordance with the present invention;

fig. 2 is a schematic of a reformer interface.

Detailed Description

the natural gas engine test system for catalytic reforming of exhaust gas-fuel and regeneration of catalyst as shown in fig. 1 comprises a reformer 1, an engine 2, a mixer 9, an intercooler 8, a three-way pipe 10, a gas tank 3, a flow regulating valve 4, a controller 22, an H2 tank 11 and an N2 tank 12; the reaction gas inlet 1A of the reformer 1 is connected with an engine exhaust pipe 14 through a first exhaust branch pipe 21A, the first exhaust branch pipe 21A is provided with a REGR front-end valve 5, an exhaust gas inlet 1B of the reformer 1 is connected with the engine exhaust pipe 14 through a second exhaust branch pipe 21B, the engine exhaust pipe 14 is connected with an exhaust port of the engine, a reformer gas outlet 1C of the reformer 1 is connected with an inlet a of a three-way pipe 10, an outlet B of the three-way pipe 10 is sequentially connected with an intercooler 8 and a mixer 9 in series through a reformed gas bypass pipe 16 (the reformed gas bypass pipe 16 is provided with a REGR rear-end valve 6, the REGR rear-end valve 6 controls the amount of reformed gas entering an engine air inlet pipe 13), and the mixer 9 is connected with an air inlet of the engine 2 through an engine air inlet; the waste gas outlet 1D of the reformer 1 is connected to the atmosphere through an atmosphere line 15; meanwhile, the outlet C of the three-way pipe 10 is communicated with an atmosphere pipeline 15 through an atmosphere valve 7, and the atmosphere valve 7 can change the communication state of the reformed gas outlet 1C of the reformer 1 and the atmosphere; the first exhaust branch pipe 21A is connected with the flow regulating valve group 4 through a mixed gas supply pipe 18, the gas tank 3 is connected with a first electric control butterfly valve of the flow regulating valve group 4 through a fuel pipeline 17, the H2 tank 11 is connected with a second electric control butterfly valve of the flow regulating valve group 4 through an H2 pipeline 19, and the N2 tank 12 is connected with a third electric control butterfly valve of the flow regulating valve group 4 through an N2 pipeline 20; the controller 22 is provided on the flow rate control valve group 4, and the controller 22 is electrically connected to the flow rate control valve group 4, the REGR front end valve 5, the REGR rear end valve 6, and the atmosphere valve 7, respectively.

in this embodiment, the REGR front end valve 5 and the REGR rear end valve 6 are electrically controlled butterfly valves, and the valve opening is controlled by an external voltage signal; the controller is a programmed logic controller, the controller 22 reads the valve opening output voltage signals of the flow regulating valve 4, the REGR front end valve 5, the REGR rear end valve 6 and the atmosphere valve 7, compares the valve opening output voltage signals with the valve opening signals preset in the controller, and correspondingly increases or decreases the voltage signals to control the valve openings of the flow regulating valve 4, the REGR front end valve 5, the REGR rear end valve 6 and the atmosphere valve 7 so as to achieve the preset valve openings.

the working principle of the natural gas engine test system is as follows:

Unburned hydrocarbon-containing exhaust gas generated by the operation of the LNG engine is branched into two paths through the first exhaust branch pipe 21A and the second exhaust branch pipe 21B to enter the reactor inlet 1A and the exhaust gas inlet 1B of the reformer 1, respectively, and the controller controls the flow regulating valve 4 through a voltage signal to supply natural gas, H2/N2 mixed gas (H2 volume fraction is 20%) or N2 to the reactor inlet 1A of the reformer 1, respectively. When the reformer 1 works, the waste gas and the natural gas are mixed and enter the reformer 1 to generate a catalytic reforming reaction to prepare hydrogen-rich reformed gas, and the reformed gas generated by the reformer circularly enters an engine to participate in combustion through the three-way valve 10, the REGR rear end valve 6 and the intercooler 8; during the catalyst reduction process, the H2/N2 mixed gas enters the reformer 1 to reduce the catalyst which is oxidized and deactivated; after the catalytic reforming test was completed, N2 entered the reformer 1 to form an inert gas atmosphere.

Therefore, the hydrogen production reaction by reforming the waste gas is carried out by utilizing the waste heat of partial waste gas, and the hydrogen-rich gas mixture generated by reforming is introduced into the engine to explore the rule of the influence of the working parameters of the reformer on the performance and the emission of the engine, so that the performance matching of the reformer and the engine is realized. Meanwhile, aiming at the problem of catalyst deactivation in the reformer, the catalyst can be reduced on line; in addition, N2 can be filled into the reformer by the rack after the experiment is finished, an inert atmosphere is formed to protect the catalyst, and the problem that the catalyst is inactivated due to oxidation of residual waste gas in the reformer in the temperature reduction process is solved.

The control method of the natural gas engine test system for catalytic reforming of exhaust gas-fuel and regeneration of catalyst comprises the following steps: wherein, the valve opening degree of 0 degree corresponds to the full-closed state, and the valve opening degree of 90 degrees corresponds to the full-open state;

When the catalytic reforming test of the exhaust gas fuel is carried out, the specific process is as follows:

The controller 22 outputs a voltage signal corresponding to the valve opening degree of 0 degrees to close the REGR rear end valve 6, and outputs a voltage signal corresponding to the valve opening degree of 90 degrees to open the atmospheric valve 7; the controller 22 outputs a voltage signal corresponding to the valve opening degree of not more than 5 degrees to adjust a first electric control butterfly valve of the flow regulating valve group 4; the controller 22 outputs a voltage signal corresponding to the valve opening degree of 90 degrees to open the REGR rear end valve 6, and outputs a voltage signal corresponding to the valve opening degree of 0 degrees to close the atmospheric valve 7; the controller 22 outputs voltage signals corresponding to valve openings of 0-90 degrees (for example, 0 degree, 10 degree, 20 degree, 30 degree, 40 degree, 45 degree, 50 degree, 60 degree, 70 degree, 80 degree and 90 degree) to adjust the REGR front end valve 5 and the first electric control butterfly valve of the flow adjusting valve group 4 to change the flow rate of the exhaust gas and the flow rate of the natural gas entering the reforming pipe of the reformer, and the influence of the space velocity and the carbon-oxygen ratio in the reformer on the performance of the LNG engine is obtained.

When the exhaust-fuel catalytic reforming test is finished, the specific process is as follows:

After the LNG engine is shut down, the controller 22 outputs a voltage signal corresponding to a valve opening of 0 ° to close the REGR front end valve 5 and the REGR rear end valve 6; the controller 22 outputs a voltage signal corresponding to the valve opening of 15-25 degrees (such as 20 degrees) to adjust a third electric control butterfly valve of the flow regulating valve group 4, and N2 airflow is continuously introduced into the reformer reaction gas inlet 1A; after a period of time (for example, after 10 minutes), the controller 22 outputs a voltage signal corresponding to the valve opening of 0 ° to close the third electrically controlled butterfly valve and the atmospheric valve 7 of the flow regulating valve group 4, so as to form a closed inert gas atmosphere to prevent the catalyst from being oxidized during the temperature reduction process to reduce the activity.

When the working time of the catalyst is too long or the operation is not proper, the catalyst loses activity, and the catalyst needs to be reduced at the moment, and the specific process is as follows:

after starting the LNG engine, the LNG engine is maintained to operate under a normal working condition, and the exhaust temperature is stabilized at 400 ℃; the controller 22 outputs a voltage signal corresponding to the valve opening degree of 0 degrees to close the REGR front end valve 5 and the REGR rear end valve 6; the controller 22 outputs a voltage signal corresponding to the valve opening degree of 90 degrees to open the atmospheric valve 7; the controller 22 respectively outputs voltage signals corresponding to valve openness of 15-25 degrees (such as 20 degrees) and 60-80 degrees (such as 70 degrees) to adjust a second electric control butterfly valve and a third electric control butterfly valve of the flow regulating valve group 4 (namely the valve openness of the second electric control butterfly valve is 15-25 degrees, and the valve openness of the third electric control butterfly valve is 60-80 degrees), and a mixture of N2 and H2 is continuously introduced into a reaction gas inlet 1A of the reformer (the volume fraction ratio of N2 to H2 is 4: 1); after the engine runs for a period of time (such as 1.5 hours), the engine is closed, the controller respectively outputs voltage signals with the valve opening degree of 0 degree and 15-25 degrees (such as 20 degrees), the second electric control butterfly valve in the flow regulating valve group is closed, the third electric control butterfly valve is regulated, and N2 is continuously introduced into a reaction gas inlet 1A of the reformer; after a period of time (for example, after 10 minutes), the controller 22 outputs a voltage signal corresponding to the valve opening of 0 ° to close the third electrically controlled butterfly valve and the atmospheric valve 7 in the flow rate regulating valve group 4, so as to form a closed inert gas atmosphere. If the test is needed, the test is carried out according to the exhaust-fuel catalytic reforming test method, and if the test is not needed, the LNG engine is shut down.

The REGR front end valve can control the flow of the reforming exhaust gas entering the reformer, and the carbon-oxygen ratio and the airspeed in the reforming reaction process can be flexibly controlled by combining with a first electric control butterfly valve in the flow regulating valve group, so that the H2 content and the yield of the reforming gas are controlled, the requirements of the engine on the reforming gas under different working conditions are met, and the matching of the reformer and the engine is realized;

after the waste gas reformer operates for a long time, the internal catalyst has deactivation phenomenon, the hydrogen production efficiency of catalytic reforming is reduced, and at the moment, the catalyst can be reduced on line. During the operation of the engine, the system closes the REGR front end valve and the REGR rear end valve, opens the atmospheric valve, adjusts an electric control butterfly valve in the flow regulating valve group to provide H2/N2 mixed gas (the volume fraction of H2 is 20%) with a certain flow rate for the reformer, reduces the deactivated catalyst under the condition, and then can continue to carry out the test.

After the reformer performance test is completed, the system closes the REGR front end valve and the REGR rear end valve and opens the atmosphere valve; an electric control butterfly valve in the flow regulating valve group is regulated to provide N2 with a certain flow rate for the reformer; closing the atmospheric valve after a period of time, and forming an inert gas protective environment in the reformer to avoid oxidation and inactivation of the high-temperature catalyst in the cooling process;

The intercooler can adjust reformed gas bypass pipe exit temperature to still have the water collection function, can carry out the water collection that the refrigerated in-process condensation is appeared to the reformed gas, avoid circulation pipeline ponding to get into the cylinder, influence engine steady operation, ponding can be discharged to the excessive height of water level in the intercooler in addition, the steady operation of maintenance system.