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This post was last edited by LQ198619 on 2017-5-25 13:27 4. Basic Composition of Compressor Looking at a compressor from the outside, the first thing you see is the casing, also called the cylinder, which is usually made of cast iron, cast steel or welded by steel plates. A high-pressure centrifugal compressor usually has two or more cylinders, which are called low-pressure cylinders, medium-pressure cylinders and high-pressure cylinders according to their gas pressures. The compressor body structure can be divided into two parts: 1. Fixed part: It is composed of cylinders, partitions, radial bearings, thrust bearings, shaft end seals and other parts, and is often called the stator. 2. Rotating part: It consists of main shaft, impeller, balance plate, thrust plate and coupling and other parts, called the rotor. Fixed part (stator part) 1. Cylinder: It is the casing of the compressor, also called the casing. It consists of a shell and an intake and exhaust chamber, which contains partitions, seals, bearings and other parts. The main requirements for it are: It has sufficient strength to withstand the pressure of gas. The flange joint surface should be tight and mainly composed of cast steel. Rotating part (rotor part) 1. The key component of the spindle compressor. It mainly plays the role of assembling the impeller, balance plate, and thrust plate. It is the center of the rotor part. 2. Impeller The impeller, also known as the working wheel, is the most important component of the compressor. The impeller rotates at high speed with the main shaft and does work on the gas. Under the action of the impeller blades, the gas rotates at high speed with the impeller. Due to the centrifugal force of the rotation and the expansion flow in the impeller, the pressure, speed and temperature of the gas are increased when it flows out of the impeller. According to the structural type, impellers are divided into three types: open, semi-open, and closed. In most cases, the latter two types of impellers are widely used in compressors. 3. Balance plate The balance plate is also called the unloading plate. In a multi-stage centrifugal compressor, due to the different gas forces on both sides of the impeller of each stage, the rotor is subject to a resultant force directed toward the low-pressure end. This resultant force is called the axial force. Axial force is harmful to the normal operation of the compressor. It can easily cause damage to the thrust bearing, causing the rotor to move to one end, causing the moving parts to shift and lose the correct relative position between the fixed components. In serious cases, the rotor may collide with fixed components and cause an accident. The balance plate is a part that uses the gas pressure difference on both sides to balance the axial force. The balance of axial force can also be balanced by the air intake on both sides of the impeller and the reverse installation of the impeller. The balance plate of the compressor is generally installed behind the final stage of the cylinder. One side of it is subject to the gas pressure of the final stage, and the other side is usually connected to the suction chamber of the machine. There is usually a labyrinth seal device on the outer circle of the balance plate to maintain the pressure difference on both sides of the plate. 4. Thrust plate Since the balance plate only balances part of the axial force, the rest of the axial force is transmitted to the thrust block on the thrust bearing through the thrust plate. The thrust plate mainly bears the axial force of the thrust bearing. Some thrust plates are placed at the high-pressure end of the compressor, and some are placed between the two stages of the compressor of the unit. Several terminology stages of centrifugal compressors: Segments are composed of an impeller and its matching fixed components: The intercooler is used as the segmented symbol cylinder: A casing is called a cylinder, and a compressor with multiple casings is called a multi-cylinder compressor row: It is the arrangement of compressor cylinders. A row can have one to several cylinders to form a cylinder. Centrifugal compressor cylinders can be divided into two types: horizontal split type and vertical split type. If the gas pressure is relatively low, the horizontally split type is usually used. If the gas pressure is relatively high and it is easy to leak, the cylindrical cylinder should be used. Centrifugal compressors are often classified according to cylinder form and are called horizontally split (MCL) and vertically split (BCL) compressors. Horizontally split type MCL Vertical split type (BCL)