Low-speed machine supercharger bearing operation monitoring and control method

Abstract

According to the technical scheme, the invention discloses a low-speed machine supercharger bearing operation monitoring and control method. An ammonia concentration sensor is additionally arranged on a breather pipe of the supercharger so as to judge whether the ammonia concentration in a bearing cavity of the supercharger exceeds a preset value or not, if yes, low-speed machine parts are disassembled and inspected at proper time, whether an ammonia fuel injection system and a bearing gap of the supercharger break down or not is determined, and after the fault is eliminated, the low-speed machine parts are disassembled and inspected. And the ammonia fuel mode operation can be recovered, so that excessive ammonia-containing waste gas is prevented from being accumulated in a bearing cavity of the supercharger, a bearing part is prevented from being corroded, and the operation safety of the supercharger is ensured.

Description

Technical Field

[0001] The present invention relates to a method for monitoring and controlling the operation of a supercharger bearing of a low-speed engine. Background Art

[0002] The supercharger bearing is one of the core components of the supercharger, and its function is to support the turbine shaft and ensure its high-speed and stable operation. The performance of the bearing directly affects the efficiency, reliability, and service life of the supercharger. The bearing reduces the friction between the turbine shaft and the bearing through the lubrication system. The bearing must be able to operate stably at extremely high speeds to ensure the high-speed operation of the turbine shaft. The bearing needs to operate stably in extreme environments of high temperature, high speed, and high load. The role of the bearing seal is crucial. A good sealing system can ensure the isolation of the gas and lubricating oil flow paths inside the supercharger. Common bearing seals usually include piston ring seals and labyrinth seals. In both cases, a small amount of exhaust gas will enter the bearing area through the gap of the bearing seal system.

[0003] In the process of the transformation of the shipping industry, if greenhouse gas emissions are to be significantly reduced, it has become an inevitable trend for ship engines to switch from using traditional fossil fuels to using green and low-carbon fuels such as LNG, methanol, hydrogen / ammonia, etc. In particular, ammonia fuel, as a zero-carbon fuel, has great potential in replacing fossil fuels. However, ammonia has a strong pungent smell and high toxicity, and leakage may cause serious harm to the environment and human health. At the same time, ammonia has a certain corrosive effect on copper, zinc, aluminum, and their alloys, especially under specific conditions (such as high temperature and high humidity will accelerate the corrosion effect of ammonia).

[0004] During the operation of a low-speed ammonia fuel engine, if the ammonia fuel burns incompletely, part of the ammonia will enter the supercharger bearing cavity through the bearing seal system along with the high-temperature exhaust gas; or when the gap of the supercharger bearing seal system increases, more ammonia-containing exhaust gas will enter the bearing cavity; when the ammonia concentration in the bearing cavity reaches a certain limit value, there will be a risk of corroding the bearing components. Operating under this state for a long time will affect the bearing and ultimately affect the operation safety of the supercharger. Summary of the Invention

[0005] The technical problem to be solved by the present invention is that during the operation of a low-speed ammonia fuel engine or when the gap of the supercharger bearing seal system increases, ammonia-containing exhaust gas will enter the supercharger bearing cavity, resulting in a corrosion risk for the bearing components.

[0006] To solve the above technical problem, the technical solution of the present invention is to disclose a method for monitoring and controlling the operation of a supercharger bearing of a low-speed engine, which is characterized by including the following steps:

[0007] Real-time detect the ammonia concentration inside the supercharger bearing through an ammonia concentration sensor;

[0008] When the ammonia concentration detected by the ammonia concentration sensor exceeds the preset value, there is a risk of ammonia leakage and ammonia corrosion, and an alarm is sent to the main control unit of the low-speed engine.

[0009] After receiving the alarm signal from the ammonia concentration sensor, the main control unit of the low-speed engine switches from the original ammonia fuel mode to the diesel mode. At this time, the single-cylinder cylinder control unit controls the cut-off of ammonia fuel injection for each cylinder and controls the injection of diesel for operation in the diesel mode.

[0010] After the main control unit of the low-speed engine switches to the diesel mode, the parts of the low-speed engine are disassembled and inspected at the appropriate time to determine whether there are faults in the ammonia fuel injection system and the bearing clearance of the turbocharger. If there are faults, after troubleshooting, the ammonia fuel mode operation is resumed.

[0011] Preferably, the ammonia concentration sensor is arranged on the turbocharger vent pipe.

[0012] In the present invention, an ammonia concentration sensor is installed on the turbocharger vent pipe to judge whether the ammonia concentration exceeds the preset value. If it exceeds, the parts of the low-speed engine are disassembled and inspected at the appropriate time to determine whether there are faults in the injection system and the bearing clearance of the turbocharger. After troubleshooting, the ammonia fuel mode operation can be resumed, thus avoiding excessive accumulation of ammonia-containing exhaust gas in the turbocharger bearing cavity, avoiding corrosion of bearing components, and ensuring the safe operation of the turbocharger. Description of the Drawings

[0013] Figure 1 It is a schematic diagram of the low-speed engine turbocharger bearing operation monitoring system. In the figure, 1 - compressor, 2 - turbine, 3 - bearing, 4 - low-speed engine scavenging box, 5 - low-speed engine cylinder, 6 - low-speed engine exhaust manifold, 7 - ammonia concentration sensor, 8 - main control unit (MCU) of the low-speed engine, 9 - single-cylinder cylinder control unit CCU. Detailed Embodiments

[0014] The present invention will be further described below in conjunction with specific embodiments. It should be understood that these embodiments are only used to illustrate the present invention and not to limit the scope of the present invention. In addition, it should be understood that after reading the content taught by the present invention, those skilled in the art can make various changes or modifications to the present invention, and these equivalent forms also fall within the scope defined by the appended claims of this application.

[0015] As the low-speed engine supercharger develops towards higher pressure ratios, the gas pressure inside the supercharger becomes increasingly high. Since the low-speed engine operates stably at medium to high loads for a long time, the supercharger also keeps running at high speed. After being compressed by the supercharger's compressor, a large flow of high-pressure-ratio air is sent into the scavenging box and then into each cylinder. Fuel combustion is completed in the cylinder, and the exhaust gas enters the exhaust manifold and then flows into the turbine of the supercharger. The turbine drives the compressor to rotate through the bearings, thus maintaining the high-speed operation of the supercharger. In the design of low-speed engine superchargers, there is generally an independent lubricating oil supply for the bearing system to ensure the normal operation of the bearings. During the operation of the supercharger, as the gas pressure increases, the gas pressure entering the bearing chamber through the gaps in the sealing system will also increase. To ensure a constant pressure in the bearing chamber, a vent pipe is generally designed to release the pressure in the bearing chamber.

[0016] During the operation of an ammonia-fueled low-speed engine, due to incomplete combustion of ammonia fuel, some exhaust gas will enter the bearing chamber through the gaps in the bearing sealing system. As the supercharger speed increases and the exhaust gas flow increases, the exhaust gas entering the bearing chamber through the gaps in the bearing sealing system will gradually increase. When a fault occurs in the supercharger bearing sealing system (such as an increased gap due to wear), more ammonia-containing exhaust gas will enter the bearings. Unburned ammonia may corrode the metal components in the bearings or be released into the external space through the vent pipe, thus causing harm to the environment.

[0017] As Figure 1 shown, in the present invention, an ammonia concentration sensor 7 is installed on the vent pipe of the supercharger. When the ammonia concentration in the bearing 3 exceeds the preset value, it indicates the risk of ammonia leakage and ammonia corrosion. The ammonia concentration sensor 7 sends an alarm to the main control unit 8 (Main Control Unit) of the low-speed engine. The main control unit 8 of the low-speed engine switches the operation mode, converting from the ammonia fuel mode to the diesel mode. The single-cylinder cylinder control unit 9 (Cylinder Control Unit) controls the cut-off of ammonia fuel injection for each cylinder and controls the injection of diesel for operation according to the diesel mode. The components of the low-speed engine are disassembled and inspected at an appropriate time to determine whether there are faults in the ammonia fuel injection system and the supercharger bearing clearance. After troubleshooting, the ammonia fuel mode operation can be restored.

Claims

1. A method for monitoring and controlling the operation of a low-speed engine supercharger bearing, characterized in that: The following steps are involved: The ammonia concentration sensor is used to detect the ammonia concentration in the supercharger bearing in real time; When the ammonia concentration detected by the ammonia concentration sensor exceeds the preset value, there is a risk of ammonia leakage and ammonia corrosion, and an alarm is sent to the low-speed engine main control unit; After receiving the alarm signal from the ammonia concentration sensor, the low-speed engine main control unit switches from the original ammonia fuel mode to the diesel mode. At this time, the single-cylinder control unit controls the cutoff of ammonia fuel injection in each cylinder and controls the diesel mode to inject diesel. After the low-speed engine main control unit is switched to diesel mode, the low-speed engine components should be disassembled and inspected at an appropriate time to determine whether there is a fault in the ammonia fuel injection system and the supercharger bearing clearance. If a fault occurs, the ammonia fuel mode can be restored only after the fault is eliminated.

2. A low-speed engine supercharger bearing operation monitoring and control method as claimed in claim 1, characterized in that: The ammonia concentration sensor is arranged on the supercharger air permeable pipe.

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