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This post was last edited by LQ198619 on 2017-5-25 at 13:28. IV. Main working principle and principle of auxiliary equipment: It does work on the gas through an impeller mounted on the rotor; its working principle is similar to that of a centrifugal pump used for transporting liquids. Gas flows into the impeller from the center; under the action of the rapidly rotating impeller blades, it rotates at high speed along with the impeller and is thrown out in a radial direction. Due to the effect of rotational centrifugal force, the pressure of the gas increases, and at the same time the flow velocity accelerates; the mechanical energy of the impeller is converted into the pressure energy and kinetic energy of the gas. As the gas passes through the diffuser and volute, its area increases and its velocity decreases, which further raises the gas pressure; this kinetic energy is also converted into pressure energy. An impeller and the fixed components that work with it constitute one stage of a compressor. After the gas passes through the first stage, the increase in pressure is limited; when a higher pressure rise is required, several stages are needed, which are installed inside a casing known as a cylinder. One cylinder can hold up to about ten stages; more stages require multiple cylinders. When gas is compressed, its temperature rises. When a higher compression ratio is required, the gas is often compressed to a certain pressure and then drawn out of the cylinder; there it is cooled in an external cooler to separate liquid droplets, thereby protecting the equipment and reducing power consumption. After that, the gas is reintroduced into the cylinder for further compression. The number of such cooling cycles determines how many sections the compressor is divided into. A segment can be at level 1 or it can include several levels. A cylinder can be divided into one section or several sections. Accessory 1: Inter-stage cooler: The temperature of the compressed gas increases; to reduce power consumption and lower the temperature of the gas entering the next stage, an inter-stage cooler is installed. (Cooling by water and air) 2. Separators at the inlet of each section: The pulsations in the airflow during compression not only increase the energy consumption for compression but also cause vibration in the unit and the connecting pipelines, leading to loose or damaged fittings. Moreover, the water mist and oil mist carried in the gas condense into water droplets and oil droplets inside the cooler, which is detrimental to the safe operation of the compressor; the presence of liquid can cause severe vibration in the compressor rotor. Function: It acts as a buffer to separate water and oil droplets, and it can remove larger particles of dust and mechanical impurities. It features level control, alarm, and high-level interlock shutdown. 3. The oil system is a system common to both turbines and compressors, including control oil and lubricating oil: it is mainly used in the turbine section. It is used for speed regulation; by altering the signal from the dial, a corresponding change in oil pressure is generated, which in turn adjusts the opening degree of the governor valve. This allows for control of the steam flow rate, and thus regulation of the turbine speed. Electrical signal → hydraulic pressure signal → governor valve → turbine speed. Keep the oil pressure between 1.3 and 1.45 Mpa. The emergency safety device can quickly release the control oil pressure to stop the turbine. Lubricating oil: Supplied to the various bearings of turbines and compressors, serving to cool, lubricate, and clean them. The oil pressure should be maintained between 0.3 and 0.45 Mpa, while the oil temperature should be kept between 35 and 45°C. Components of the oil system A: Oil tank: Equipment for supplying, recovering, settling, and storing oil. It contains an electric (or steam) heater that raises the temperature to 35–45°C during operation. Generally, a baffle is installed between the return oil flow and the pump inlet, allowing sufficient time for impurities in the oil to settle and gases to be released. An exhaust pipe is installed at the top (connected to an exhaust fan) to remove gases and water vapor from the tank; some units also have nitrogen pipes through which nitrogen is introduced to prevent the oil in the tank from coming into contact with air and oxidizing. B. Oil pumps: Generally, two pumps are installed, with two main operating pumps – one in use and one as a backup. The backup pump is set to start automatically; it comes online when the main oil pump fails or there is a problem with the oil system, causing the system oil pressure to drop below a certain set value. There are also systems equipped with emergency oil pumps; in an emergency situation, the main and auxiliary oil pumps lose power and cannot operate. The emergency oil pump is designed to protect the compressor, and it uses direct current power (the power source comes from a DC generator in emergency conditions, which is typically available throughout the plant). ) If the unit is particularly large and gas-driven, it can be considered. If electric drive is not needed at all. The presence of a high-level fuel tank meets the requirement for rotor coasting during emergency shutdowns. C. Oil cooler: Cools the oil returning to the tank, whose temperature has risen, in order to keep the inlet oil temperature within the range of 35–45°C. Generally, two units are used, one in operation and one as a backup, either for switching over during maintenance or simultaneously when the cooling effect is insufficient. When the oil temperature is low while driving, the cooling water is not used; it is only added after the oil temperature rises after the vehicle has been running for a while. D. Oil filter: Filters out impurities in the oil at the pump outlet to ensure the quality of the lubricating oil. Two units, one in use and one as backup; it features a pressure difference alarm and allows for online switching. However, the oil filter is generally cleaned during parking for maintenance, in order to prevent misoperations or abnormal conditions from affecting the proper operation of the compressor. Generally, impurities larger than 10 micrometers are removed. E. High-level oil tank: also known as the emergency oil tank. It is a protective facility that ensures the lubrication needs of the equipment in the event of an equipment failure. Therefore, during normal operation, the high-level oil tank must always maintain a certain liquid level and have overflow. This tank is put into use before driving; oil enters from the bottom and overflows back to the system from the higher level. When the main pump fails and the auxiliary pump does not start in time, the lubricating oil from the high-level oil tank will flow to various lubrication points through the oil inlet pipes under the force of gravity, in order to maintain the lubrication required during the shutdown of the unit. The general supply duration is not less than 5 minutes. The high-level oil tank is usually located at a height of no less than 5 meters from the axis of the machine unit. The length of the pipelines should be kept as short as possible, with as few bends as feasible, in order to minimize backflow resistance and ensure that the pressure is sufficient to meet the lubrication requirements of the machine unit. A check valve should be installed on the main pipeline from the lubricating oil pump outlet to before the oil enters the machine. Once the main pump stops operating and the auxiliary pump does not start to supply oil in time, the check valve closes immediately, preventing the lubricating oil from flowing back from the high-level oil tank. This ensures that the oil must pass through the bearings before entering the return pipeline and then returning to the oil tank, thus avoiding a short circuit of the lubricating oil in the high-level tank and preventing damage to the bearing shells during the shutdown of the machine.