1. Working principle of diesel engine
A. Diesel is a power machine . The power machine is also called prime mover . It converts natural energy ( chemical energy of water , wind , sun and various fuels ) into mechanical movement that can be directly utilized , and drives other machines .
B. The diesel engine directly injects the chemical fuel (diesel) into the cylinder and relies on the thermal explosive force produced by the combustion of the fuel to promote the external work of the piston.
C. The conversion of heat energy and mechanical energy in diesel oil is accomplished through four processes: piston working in cylinder, continuous air intake, compression, working and exhaust.
2. Generator/Alternator
After starting the diesel engine, it depends on the residual magnetic voltage of the motor, the excitation current provided by the rectifier to the magnetic field of the AC excitation machine, and the armature voltage of the AC excitation motor increases gradually. The AC voltage is fed into the host magnetic field after the rotation rectifier, which makes the main generator establish the voltage. When the speed is close to the rated value, the voltage regulator AVR makes the generator rise rapidly and stabilize at the rated value.
3. Control System
The control system monitors the operation of the whole unit, including the diesel engine and the motor. The sensors on the diesel engine are used to control the high water temperature alarm shutdown, the overspeed alarm shutdown and the low oil pressure alarm shutdown of the diesel engine, and to ensure the diesel engine to run in the normal working state.
Operation specification
The selection of position and size of generator room should be very careful. If the generator room is not suitable, the performance of generator set can not be brought into full play, which brings difficulties to operation and maintenance.
The generator room is designed in the following order:
Determine the location, area and height of the generator room.
Determine the basis.
Determination of cooling system.
Determine the ventilation system.
Determine the fuel system.
Identify the exhaust system.
Considerations for use:
1. The properties of diesel have great influence on the power, economic performance and reliability of diesel engine.
2. Oil with CF or VOLVO special oil.
3. Cooling fluid
Coolant should provide adequate heat transfer capacity, in addition to the main anti-rust, anti-freezing. The coolant shall be mixed with water and ethylene glycol or corrosives. The PH value of water is between 6 and 8. Clean water or distilled water should be used in accordance with ASTM 4985. The specific mixing ratio is 50 VOLVO antifreeze and 50% pure water. It can be used throughout the year without freezing when the temperature is about -40.
Generator Set Running
Machine pressure should be within 2-5 Bar range.
Check whether there is oil leakage or leakage in connection of parts and parts.
Exhaust smoke color is normal, there is no abnormal noise.
No-load low speed running time should not be too long.
When diesel engine temperature, oil pressure and so on are normal, the engine speed should be increased to the rated value, and the engine should be able to run stably.
progressive loading
The increase of load and rotational speed should be gradually and uniformly increased, and sudden increase and sudden reduction of load should not be allowed under any special circumstances.
Generator Set Shutdown
Normal shutdown
An overall inspection should be carried out to observe whether the machine is malfunctioning so that it can be handled after the shutdown. During the downtime, the method of opening the decompression mechanism or closing the fuel tank switch should not be used to stop the machine.
Unloading the load gradually before shutdown, running 3-5 minutes without load, cooling evenly in many departments, this is especially important in turbocharger.
Stop by stopping device, such as stop solenoid valve, solenoid, etc.
Emergency Shutdown
In one of the following situations , the diesel generator set must be stopped
Oil pressure gauge indicates sudden drop or no pressure
The cooling water temperature or oil temperature rises sharply.
The speed automatically rises, and there is a flying car.
Abnormal tapping or loosening of transmission mechanism.
The diesel engine has explosive latent accident on the spot. At present, the control system of the unit is usually equipped with self-protection system, such as oil pressure, water temperature, overspeed protection, and emergency stop device, which makes the diesel engine stop by turning off the throttle. If necessary, stop the air filter by blocking it.
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