I. features of silent generator set
The silent generator set is carefully designed by introducing foreign low-noise generator and engine technology. Silent generator set design concept advanced, complete variety.
In addition to a series of diesel generating sets and various functions of diesel generating sets, the silent generating sets also have the following features:
1. Low noise of the unit, compact overall structure and small space;
2. The box body is all removable. The box body is made of steel plate splicing.
3. The box body adopts multi-layer impedance mismatch silencer structure and large internal impedance muffler. The box body is designed reasonably. The box body is equipped with a large-capacity oil tank inside, and two overhaul doors are provided at the same time to facilitate the unit's fault maintenance.
4. At the same time, there are observation Windows and emergency shutdown buttons of the unit on the box body, so as to observe the operation of the unit and stop the unit at a faster speed in case of emergency to avoid damage to the unit
Features of silent generator:
1. Vibration damping facilities. High-performance shock absorbers are used between the diesel engine and generator and the bridge frame to reduce noise generated by vibration.
2. Sound insulation cover: the sound insulation cover is made of four to five layers of sound absorbing materials. The technology is mature and the sound insulation effect is obvious.
3. The inlet wind silencer, a labyrinth air silencer with three layers of sound-absorbing materials, not only ensures sufficient entrance of fresh air, but also effectively seals off the noise.
4. Exhaust air silencer, a labyrinth exhaust silencer with three-layer sound-absorbing materials, not only ensures unobstructed exhaust air, but also effectively seals off noise propagation and diffusion.
5. The adoption of exhaust muffler and impedance composite muffler greatly reduces the noise when the exhaust gas is discharged, and the emission can meet the national standards.
6. Power cable connection adopts fixed junction box structure and is directly connected outside the box.
Detailed parameters of the silent generator set
The complete set of units is generally composed of diesel engine, generator, control box, fuel tank, storage battery for starting and control, protective device and emergency cabinet
Connection between engine and generator:
1. Flexible connection (connect the two parts with a coupling)
2. Steel connection: high-strength bolts connect the generator's steel connection piece with the engine flywheel, and then put it on the common base frame, which is then equipped with various protective sensors (oil probe, water temperature probe, oil pressure probe, etc.) to display various transmission by the control system
The working state of the sensor.
The control system is connected to the generator and sensor by cable to display data.
Iii. Working principle of silent generator set
A diesel engine drives a generator that turns diesel energy into electricity.
In the diesel engine cylinder, the clean air filtered by the air filter is fully mixed with the high-pressure atomized diesel injected by the fuel injection nozzle. Under the upward extrusion of the piston, the volume is reduced and the temperature is rapidly increased to reach the burning point of diesel. Diesel is ignited, the mixture burns violently, and the volume expands rapidly, pushing the piston down, known as' work '.
Each cylinder works in a certain order, and the thrust acting on the piston through the connecting rod becomes the force that drives the crankshaft to rotate, thus driving the crankshaft to rotate.
When the brushless synchronous alternator is installed with the crankshaft of the diesel engine, the rotation of the diesel engine can be used to drive the rotor of the generator. With the principle of "electromagnetic induction", the generator can output the induced electromotive force, and the closed load loop can generate the current.
The basic operating principles of a generator set are described here only. A range of diesel and generator controls, protective devices and loops are needed to achieve a reliable and reliable electrical output.
If run for more than 12 h, its power output will be lower than the rated power of diesel engine is generally about 90% diesel generator single cylinder or multi cylinder four stroke diesel engine, I only work about single cylinder four stroke diesel engine under the basic principle: diesel engine starting is through human or other power rotation diesel engine crankshaft to the piston at the top of airtight cylinder reciprocating movement up and down. The piston in motion completes four stroke: intake stroke, compression stroke, combustion and work (expansion) stroke and exhaust stroke. When the piston moves from top to bottom, the intake valve opens and fresh air filtered by the air filter enters the cylinder to complete the intake stroke. The piston moves from the bottom up, the inlet and exhaust doors are closed, the air is compressed, the temperature and pressure are increased, and the compression process is completed. When the piston is about to reach the top, the injector sprays the filtered fuel into the combustor in a mist form and mixes it with the high-temperature and high-pressure air, and immediately catches fire by itself. The high-pressure pressure pushes the piston to work downward and drives the crankshaft to rotate to complete the work stroke.
Iv. Mute generator set operation method
Description of diesel generator set: manual operation
1. Check the proper amount of fuel, oil and cooling water before starting the diesel generator set manually. The inadequate should be timely supplement. The unit should be free of oil leakage and water leakage.
2. The automatic control button of the automatic controller of diesel generator set shall be pushed to the middle position.
3. Open the key of the startup circuit, and continue to twist the key to start the diesel engine to the right. After successful startup, return the key to the charging position.
4. When the diesel generating set is shut down, the key shall be put back to the middle position of the diesel generating set in time
Automatic operation
1. Under normal power supply conditions, push the automatic control button of the automatic controller upward to the "automatic" position. Manual starting of the diesel engine is prohibited. When the power is cut off, the diesel generator set can start automatically and supply power to the grid automatically via the ATS switch.
2. After the diesel generator sets start operation automatically, the key switch shall be pressed to the charging position in time.
3. The unit can stop automatically when the power supply calls. After the shutdown, the key switch should be set to the middle position to prevent the battery from discharging, affecting the next use of diesel generator set instructions: maintenance
1. After 60 hours of operation, the diesel generator set needs to replace the oil, clean the wood filter and empty filter.
2. The electrolyte of the battery should be regularly checked, and it should be replenished in time if it is insufficient.
3. Check the belt tightness frequently, adjust the tensioning mechanism and keep the tension state.
4. Turn on the water heating and oil heating switch in cold season to keep the unit at a certain temperature and ensure the normal operation of the diesel generator
Five, silent generator set four stroke combustion process
Combustion process:
1. Combustion preparation stage (flame retardation stage)
The period of preparation for combustion from the injection of fuel to the onset of fire. In this stage, the fuel requires physical preparation such as heating, evaporation, diffusion and mixing with airflow, as well as chemical preparation such as decomposition and oxidation.
2. Rapid combustion phase
The period from the point of fire to the point of high pressure in the cylinder. When a small amount of diesel oil catches fire, the number of combustible mixture continues to increase and the flame spreads rapidly, the combustion speed is accelerated and the heat release rate is high. The pressure and temperature in the cylinder increased sharply. However, if the pressure rises too fast, the crank-link mechanism will be subjected to a great impact load, accompanied by sharp percussion sound, and the diesel engine works rough blasting, which should be restricted. In order to make diesel engine work smoothly, the growth rate of pressure shall not exceed 292 kpa to 588 kpa / 1 ° (crank Angle)
3. Primary stage (slow burning period)
The main combustion stage is the stage between the explosion pressure occurrence point and the high combustion temperature occurrence point. This stage is characterized by the end of the fuel injection, during which most of the fuel is burned, giving off about 80% of the total heat, and the gas temperature rises to a high point. However, as the piston moves down, the cylinder volume increases, so the pressure in the cylinder does not change much. The oil supply ends at this stage.
4. Post-combustion stage
The period from the point of high combustion temperature to the end of combustion. At this stage, has a large number of oxygen consumption, fuel injection, no late enough oxygen mixture for combustion, combined with further down, the piston within the cylinder pressure and temperature have a larger decline, the combustion condition worsened, so that the fuel combustion is incomplete, appear exhaust smoke phenomenon, make relevant parts heat load increases, affect the efficiency and service life, so try to reduce combustion period after burning
The noise source and processing method of the silent generator set
Generator noise includes electromagnetic noise caused by magnetic pulsation between stator and rotor and mechanical noise generated by rolling bearing rotation
Noise control measures
On the premise of ensuring that the ventilation condition of diesel generator sets does not reduce the output power, the inlet and outlet channels and exhaust systems are processed with efficient sound absorbing materials and noise-cancelling equipment, so that the noise emission reaches the national standard of 85db.
Reduce exhaust noise.
Exhaust noise is the main noise source of the unit, which is characterized by high noise level and fast exhaust speed.
Governance is difficult. With a specially designed impedance composite muffler, the exhaust noise can generally be reduced by 40-60db.
Noise reduction of axial-flow fan.
When reducing the noise of generator cooling fan, two problems must be considered. The second is the required amount of silencing. For the above two points, resistance can be selected
The air inlet of the blade muffler shall be arranged in the same line as the generator set and the air outlet. The air inlet shall be equipped with resistance blade muffler. As the pressure loss of the air inlet is within the allowable range, the air flow in and out of the machine room can be naturally balanced and the ventilation and heat dissipation effect is obvious.
The indoor air communication and sound insulation of the machine room will prevent the air in the room from convection when the closed water-cooled generator is shut down, and the high temperature in the room cannot be lowered in time. The low-noise axial-flow fan can be adopted and the resistive blade muffler can be added.
