Dual fuel engine crankcase explosion prevention monitoring and control method

Abstract

The application discloses a kind of dual-fuel engine crankcase explosion-proof monitoring and control method, belong to crankcase monitoring technical field, comprising: real-time monitoring gas pressure and temperature in crankcase and the methane concentration of crankcase breather pipe, when pressure, temperature and methane concentration are less than corresponding first limit respectively, engine normal operation;When pressure and / or temperature and / or methane concentration is greater than or equal to corresponding first limit, and duration exceeds t seconds, engine is in fault operation state, issues corresponding alarm, executes limit torque action, and according to whether pressure and / or temperature and / or methane concentration exceeds corresponding limit value, nitrogen purging action or parking is executed to crankcase, monitoring effect is good, the load control of engine, the forced purging control of crankcase is integrated, initiatively carries out source control, to effectively prevent crankcase explosion, simultaneously, the application simple structure is suitable for small-bore engine model limited by cost and installation arrangement limit.

Description

Technical Field

[0001] This invention belongs to the field of crankcase monitoring technology, specifically relating to a method for monitoring and controlling the explosion prevention of a dual-fuel engine crankcase. Background Technology

[0002] Currently, existing engines typically employ crankcase oil mist detectors and main bearing temperature sensors for monitoring and prevention of crankcase explosions. When oil mist concentration exceeds limits or temperature is too high, an alarm is triggered, and the engine reduces torque or shuts down. This monitoring method is only mandatory for engines with large cylinder bores and a certain power output. Small-bore, low-power engines are difficult to install due to cost and installation limitations. Furthermore, dual-fuel engines inevitably experience blow-by in dual-fuel mode, resulting in a certain concentration of natural gas in the crankcase. However, conventional probes cannot distinguish between methane and oil mist concentrations in the crankcase, leading to frequent false alarms and insufficient protection for the crankcase of such engines. Additionally, existing control technologies, even after detecting problems such as high crankcase oil mist concentrations, cannot effectively control the hazard source. Summary of the Invention

[0003] The technical problem to be solved by the present invention is to provide a method for monitoring and controlling the crankcase explosion prevention of a dual-fuel engine, which can effectively monitor the gas and oil mist mixture in the crankcase and control it from the source to prevent the crankcase from exploding and improve system reliability.

[0004] To solve the above-mentioned technical problems, the technical solution of the present invention is as follows:

[0005] A method for monitoring and controlling the explosion prevention of a crankcase in a dual-fuel engine includes: real-time monitoring of the gas pressure and temperature inside the crankcase and the methane concentration in the crankcase vent pipe; when the pressure, temperature, and methane concentration are each less than a corresponding first limit, the engine operates normally; when the pressure and / or temperature and / or methane concentration are greater than or equal to the corresponding first limit and the duration exceeds t seconds, the engine is in a fault operation state, a corresponding alarm is issued, torque limiting action is performed, and nitrogen purging or shutdown is performed on the crankcase depending on whether the pressure and / or temperature and / or methane concentration exceeds the corresponding limit.

[0006] Furthermore, when the temperature inside the crankcase is greater than or equal to the first temperature limit but less than the second temperature limit, a torque limiting action is performed, a high temperature alarm is issued, and a nitrogen purging action is performed on the crankcase.

[0007] Furthermore, when the crankcase pressure and / or temperature are greater than or equal to the corresponding second limit and the duration exceeds t1 seconds, an overpressure alarm or overtemperature alarm is issued, and the machine is stopped.

[0008] Furthermore, the gas pressure after the oil mist separator in the vent pipe is monitored in real time. When the pressure in the crankcase is greater than or equal to the first pressure limit but less than the second pressure limit, the difference between the crankcase pressure and the vent pipe pressure is calculated.

[0009] Furthermore, when the difference does not exceed the set value, a torque limiting action is performed, a high pressure alarm is issued, and a nitrogen purging action is performed on the crankcase; when the difference exceeds the set value, a torque limiting action is performed, and a vent pipe blockage alarm is issued.

[0010] Furthermore, when the engine is in dual-fuel mode, if the methane concentration is greater than or equal to the first concentration limit but less than the second concentration limit, and the crankcase pressure and / or temperature is less than the corresponding first limit, a torque limiting action is performed, a high methane concentration alarm is issued, the engine switches to pure diesel mode, and a nitrogen purging action is performed on the crankcase.

[0011] Furthermore, when the pressure and / or temperature inside the crankcase is greater than or equal to the corresponding first limit but less than the corresponding second limit, an alarm and / or purging will be triggered based solely on the crankcase pressure and temperature conditions.

[0012] Furthermore, when the engine is in dual-fuel mode, if the methane concentration exceeds the second concentration limit and the crankcase pressure and / or temperature exceeds the corresponding first limit, an alarm for excessive methane concentration will be issued, and the engine will stop.

[0013] Furthermore, when performing nitrogen purging on the crankcase, the alarm enable is turned off. After the purging action lasts for t2 seconds, the purging is completed, and the alarm enable is turned on. When the alarm enable is turned off, the alarm signals for pressure, temperature, and concentration are not displayed, and the purging and shutdown actions caused by excessive crankcase pressure, temperature, and methane concentration are not performed.

[0014] Furthermore, when the engine is in a faulty operating state, an audible and visual warning will be given to manually stop the engine.

[0015] After adopting the above technical solution, the beneficial effects of the present invention are:

[0016] The dual-fuel engine crankcase explosion prevention monitoring and control method of the present invention includes: real-time monitoring of gas pressure and temperature in the crankcase and methane concentration in the crankcase vent pipe; when the pressure, temperature, and methane concentration are respectively less than the corresponding first limit, the engine operates normally; when the pressure and / or temperature and / or methane concentration are greater than or equal to the corresponding first limit and the duration exceeds t seconds, the engine is in a fault operation state, a corresponding alarm is issued, torque limiting action is executed, and nitrogen purging action or shutdown is performed on the crankcase according to whether the pressure and / or temperature and / or methane concentration exceeds the corresponding limit; and the crankcase is monitored by collecting crankcase data. The pressure, temperature, and methane concentration in the crankcase can be used to conveniently determine whether the two conditions for an explosion are met: first, sufficient concentration of gas or oil mist to cause an explosion; and second, whether there is an ignition source. Based on these conditions, the engine's operating status can be determined. The monitoring of the gas and oil mist mixture in the crankcase is effective, and the engine load control and crankcase forced purging control are integrated into one system to actively control the source, thereby effectively preventing crankcase explosions and improving system reliability. At the same time, the invention has a simple structure and is easy to install, making it particularly suitable for small-bore engines with limited cost and installation layout constraints. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of the dual-fuel engine crankcase explosion prevention monitoring and control method of the present invention. Detailed Implementation

[0018] The present invention will be further described below with reference to the accompanying drawings and embodiments. Preferred embodiments of the present invention are shown in the accompanying drawings. The purpose of the accompanying drawings is to supplement the description of the textual part of the specification with graphics, so that people can intuitively and vividly understand each technical feature and the overall technical solution of the present invention, but they should not be construed as limiting the scope of protection of the present invention.

[0019] like Figure 1 As shown, a method for monitoring and controlling the explosion prevention of a crankcase in a dual-fuel engine includes: real-time monitoring of the gas pressure P and temperature T inside the crankcase, as well as the methane concentration C in the crankcase vent pipe. The engine operates normally when the pressure P, temperature T, and methane concentration C are all below their respective first limits; that is, when the three conditions—crankcase pressure P less than the first pressure limit P1, temperature T less than the first temperature limit T1, and methane concentration C less than the first concentration limit C1—are simultaneously met. The first pressure limit P1, first temperature limit T1, and first concentration limit C1 are all preset by operators based on experience, and the set limits will differ for different configurations of dual-fuel engines.

[0020] For a gas explosion to occur inside a crankcase, two conditions must be met: first, there must be a sufficient concentration of gas or oil mist to cause an explosion; second, there must be an ignition source. The most direct external manifestation of this is the change in pressure and temperature inside the crankcase. An explosion will only occur when the temperature and pressure reach a certain level. Therefore, detecting any abnormal increases in temperature and pressure inside the crankcase can effectively prevent crankcase explosions.

[0021] The crankcase vent pipe is located after the oil-gas separator. The oil mist mixture is separated by the oil mist separator, and the oil and water mixed in the gas flow back to the crankcase. The separated gas is discharged from the crankcase through the vent pipe. The probe at this location is free from oil mist interference and can effectively monitor the methane concentration C. Based on the methane concentration C, it can determine whether corresponding control of the dual-fuel engine is required.

[0022] like Figure 1 As shown, when the pressure P and / or temperature T and / or methane concentration C are greater than or equal to the corresponding first limit and the duration exceeds t seconds, the engine is in a fault operation state, issues a corresponding alarm, performs torque limiting action, and performs nitrogen purging action on the crankcase or stops the engine depending on whether the pressure P and / or temperature T and / or methane concentration C exceed the corresponding limit.

[0023] Specifically, when any one of the following three conditions is met: crankcase pressure P greater than or equal to the first pressure limit P1, temperature T greater than or equal to the first temperature limit T1, or methane concentration C greater than or equal to the first concentration limit C1, the engine will issue a corresponding temperature, pressure, or concentration alarm and limit torque to control the engine load. Subsequently, depending on the specific situation, appropriate measures will be taken, such as nitrogen purging, engine shutdown, or alarm-only intervention. This involves promptly purging flammable and explosive gases, injecting nitrogen into the crankcase to cut off the conditions for an explosion, or shutting down the engine to reduce gas concentration accumulation and control temperature rise within the crankcase, actively controlling the source to prevent a crankcase explosion.

[0024] like Figure 1 As shown, when the engine is in a faulty operating state, an audible and visual prompt is given to manually stop the engine. This means that manual intervention can be carried out at any time during this stage to improve reliability.

[0025] like Figure 1 As shown, the crankcase temperature signal T is collected in real time. When the crankcase temperature T is greater than or equal to the first temperature limit T1 but less than the second temperature limit T2, a torque limiting action is executed, a high temperature alarm is issued, and a nitrogen purging action is performed on the crankcase. The second temperature limit T2 is set in advance by the operator based on experience.

[0026] like Figure 1As shown, the gas pressure after the oil mist separator in the vent pipe is monitored in real time. When the crankcase pressure P is greater than or equal to the first pressure limit P1 but less than the second pressure limit P2, the difference ΔP between the crankcase pressure P and the vent pipe pressure P′ is calculated. When the difference ΔP does not exceed the set value A, it is determined that there is an explosion risk in the crankcase, a torque limiting action is executed, a high pressure alarm is issued, and a nitrogen purging action is performed on the crankcase. When the difference ΔP exceeds the set value A, a torque limiting action is executed, but purging is not performed, and a vent pipe blockage alarm is issued simultaneously.

[0027] like Figure 1 As shown, when the crankcase pressure P and / or temperature T are greater than or equal to the corresponding second limit, that is, when the crankcase pressure P is greater than the second pressure limit P2 and / or the temperature T is greater than the first temperature limit T2, and the duration exceeds t1 seconds, an overpressure alarm or an overtemperature alarm is issued, and the machine is stopped.

[0028] like Figure 1 As shown, the concentration C of methane in the crankcase breather pipe is collected in real time. When the engine is in dual-fuel mode, if the methane concentration C is greater than or equal to the first concentration limit C1 but less than the second concentration limit C2, and if the crankcase pressure P and / or temperature T are less than the corresponding first limit (i.e., there is no abnormal increase), a torque limiting action is executed, a high methane concentration alarm is issued, the engine switches to pure diesel mode, and a nitrogen purging action is performed on the crankcase to prevent the presence of a large amount of flammable gas in the crankcase and reduce the risk of explosion. The second concentration limit C2 is set in advance by the operator based on experience.

[0029] like Figure 1 As shown, when the crankcase pressure P and / or temperature T are greater than or equal to the corresponding first limit but less than the corresponding second limit, the alarm and / or purging are performed only based on the crankcase pressure P and temperature T. Specifically, if the crankcase temperature T is greater than or equal to the first temperature limit T1 but less than the second temperature limit T2, a torque limiting action is executed, a high temperature alarm is issued, and the crankcase is purged with nitrogen. If the crankcase pressure P is greater than or equal to the first pressure limit P1 but less than the second pressure limit P2, the difference ΔP is used for judgment. When the difference ΔP does not exceed the set value A, it is determined that there is an explosion risk in the crankcase, a torque limiting action is executed, a high pressure alarm is issued, and the crankcase is purged with nitrogen; when the difference ΔP exceeds the set value A, a torque limiting action is executed, but purging is not performed, and a vent blockage alarm is issued simultaneously.

[0030] like Figure 1As shown, when the engine is in dual-fuel mode, if the methane concentration C is greater than the second concentration limit C2, and the crankcase pressure P and / or temperature T are greater than the corresponding first limit, that is, when the crankcase pressure P and / or temperature T abnormally increase, causing the crankcase pressure P to be greater than the first pressure limit P1 and / or the temperature T to be greater than the first temperature limit T1, an alarm for excessive methane concentration is issued, and the engine stops.

[0031] In this application, when performing nitrogen purging on the crankcase, the purging enable is activated, and a control signal (not limited to DC24, AC220, or passive switch quantity) is output. This signal is linked to the nitrogen purging system. Upon receiving this signal, the solenoid valve controlling the nitrogen purging opens, and the alarm enable is deactivated. After the purging action lasts for t2 seconds, once purging is complete, the alarm enable is activated, allowing the system to continue purging or shutdown control based on crankcase pressure P, temperature P, and methane concentration C in the breather pipe. When the alarm enable is deactivated, alarm signals for pressure, temperature, and concentration are not displayed, and purging and shutdown actions caused by excessively high crankcase pressure, temperature, and methane concentration are not executed, preventing false alarms caused by pressure increases due to nitrogen purging.

[0032] The dual-fuel engine crankcase explosion prevention monitoring and control method of this application determines the engine's operating status by real-time monitoring of the gas pressure and temperature in the crankcase and the methane concentration in the crankcase breather pipe. When the engine is in a faulty state, it takes corresponding actions such as alarm, torque limiting, nitrogen purging of the crankcase, and shutdown when the situation is serious. It has good monitoring effect on the gas and oil mist mixture in the crankcase and integrates engine load control, forced crankcase purging control, and prevention of misoperation into one, actively controlling the source, thereby effectively preventing crankcase explosion and improving system reliability. At the same time, the invention has a simple structure and is easy to install, and is especially suitable for small-bore engines with limited cost and installation layout.

[0033] While specific embodiments of the present invention have been described above, those skilled in the art should understand that the described embodiments are merely some, not all, of the present invention. These are merely illustrative examples, and the scope of protection of the present invention is defined by the claims. Those skilled in the art can make various changes or modifications to these embodiments without departing from the principles and essence of the present invention and without any inventive effort, but all such changes and modifications fall within the scope of protection of the present invention.

Claims

1. A method for monitoring and controlling the explosion prevention of a crankcase in a dual-fuel engine, characterized in that, include: The engine operates normally when the pressure, temperature and methane concentration in the crankcase and the crankcase vent pipe are monitored in real time. When the pressure and / or temperature and / or methane concentration are greater than or equal to the corresponding first limit and the duration exceeds t seconds, the engine is in a fault operation state, issues the corresponding alarm, performs torque limiting action, and performs nitrogen purging action on the crankcase or stops the engine depending on whether the pressure and / or temperature and / or methane concentration exceeds the corresponding limit. The gas pressure after the oil mist separator in the vent pipe is monitored in real time. When the pressure in the crankcase is greater than or equal to the first pressure limit but less than the second pressure limit, the difference between the crankcase pressure and the vent pipe pressure is calculated. When the difference does not exceed the set value, a torque limiting action is performed, a high pressure alarm is issued, and a nitrogen purging action is performed on the crankcase. When the difference exceeds the set value, a torque limiting action is performed, and a vent pipe blockage alarm is issued. When the temperature inside the crankcase is greater than or equal to the first temperature limit but less than the second temperature limit, the torque limiting action is executed, a high temperature alarm is issued, and the crankcase is purged with nitrogen. When the engine is in dual-fuel mode, if the methane concentration is greater than or equal to the first concentration limit but less than the second concentration limit, and if the crankcase pressure and / or temperature is less than the corresponding first limit, a torque limiting action is performed, a high methane concentration alarm is issued, the engine switches to pure diesel mode, and a nitrogen purging action is performed on the crankcase.

2. The method for monitoring and controlling the explosion prevention of a dual-fuel engine crankcase according to claim 1, characterized in that, When the crankcase pressure and / or temperature is greater than or equal to the corresponding second limit and lasts for more than t1 seconds, an overpressure alarm or overtemperature alarm is issued, and the machine is stopped.

3. The method for monitoring and controlling the explosion prevention of a dual-fuel engine crankcase according to claim 1, characterized in that, When the pressure and / or temperature inside the crankcase is greater than or equal to the corresponding first limit but less than the corresponding second limit, an alarm and / or purging will be triggered based solely on the crankcase pressure and temperature conditions.

4. The method for monitoring and controlling the explosion prevention of a dual-fuel engine crankcase according to claim 1, characterized in that, When the engine is in dual-fuel mode, if the methane concentration exceeds the second concentration limit and the crankcase pressure and / or temperature exceeds the corresponding first limit, a high methane concentration alarm will be issued, and the engine will stop.

5. The method for monitoring and controlling the explosion prevention of a dual-fuel engine crankcase according to claim 1, characterized in that, When performing nitrogen purging on the crankcase, the alarm enable is turned off. The purging action lasts for t2 seconds and is completed. Then the alarm enable is turned on. When the alarm enable is turned off, the alarm signals for pressure, temperature and concentration are not displayed. The purging and shutdown actions caused by excessive crankcase pressure, temperature and methane concentration are not performed.

6. The method for monitoring and controlling the explosion prevention of a dual-fuel engine crankcase according to any one of claims 1 to 5, characterized in that, When the engine is in a faulty operating state, a manual stop audio and visual warning will be issued.

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