Working principle of centrifugal compressor
1. Working principle
The steam turbine (or motor) drives the compressor spindle impeller to rotate. Under the action of centrifugal force, the gas is dumped into the diffuser behind the working wheel. A thin area is formed in the middle of the working wheel, and the front gas enters the impeller from the inlet part of the middle of the working wheel. Because the working wheel is continuously rotating, the gas can be continuously thrown away, thus maintaining the continuous flow of gas in the pneumatic machine. The gas increases pressure because of centrifugal action, and also can leave the working wheel at great speed. The gas gradually reduces the speed through the diffuser, and the kinetic energy is changed into hydrostatic energy, which further increases the pressure. If the pressure of a working impeller is not enough, the pressure of the outlet can be achieved by making the multistage impeller work in series. The interstage series is realized by bending through the recirculant. This is the working principle of a centrifugal compressor.
Two. Basic structure
The centrifugal compressor is composed of two parts of the rotor and the stator. The structure is shown in Figure 1. The rotor includes the rotating shaft, the impeller, the shaft sleeve, the balance plate, the thrust disc and the coupling parts fixed on the axis. The stator has a cylinder, which is located in the various baffles on the cylinder and the bearing and other parts. There is also a sealing element that needs to be sealed between the rotor and the stator. The role of each component is introduced as follows.
Advantages and disadvantages of centrifugal air compressor with centrifugal air compressor
1. The impeller
Impeller is the most important part of centrifugal compressor. The mechanical work of the driving machine means that the gas can be obtained through the high-speed rotary impeller to work for the gas, and it is the only working component in the compressor, also known as the working wheel. The impeller is usually a closed impeller composed of wheel cover, wheel disk and blade, and a half open impeller with no wheel cover.
2. The main shaft
The main shaft is to support rotating parts and transfer torque. According to its structural form. There are two kinds of staircase and light axis, and the light axis has the features of simple shape and convenient processing.
3. Balance plate
In the multi-stage centrifugal compressor, because the force acting on each side of the impeller is different, the rotor is subjected to a resultant force pointing to the low pressure end, which is called the axial force. Axial force is harmful to the normal operation of compressor. It is easy to cause thrust bearing damage and cause the rotor to move to one end, which leads to the relative position between the moving parts and the fixed elements. If the condition is serious, the rotor may collide with the fixed parts and cause accidents. A balance plate is a part that uses the pressure difference between the two sides of the gas to balance the axial force. It is the final side pressure side of the impeller disk gap pressure, the other side to the atmosphere or the intake pipe, usually only a portion of the balance disc balance axial force, residual axial force by the thrust bearing, the outer edge of the balance disc to install gas seal to prevent gas leakage, maintain pressure side two. The balance of the axial force can also be balanced by the two sides of the impeller and the reverse installation of the impeller.
4. Thrust disc
The only part of the balance disc balance the axial force, the axial force of the thrust plate to the thrust bearing of the thrust block, a force balance, the contact surface of the thrust plate and the thrust block, should be very smooth, in both the gap be filled with suitable lubricating oil, in the normal operation of the thrust block not to wear in the centrifugal compressor starting when the rotor will move to the other end, in order to ensure the normal position of the rotor, the rotor thrust required two positioning, the reason is when the compressor starts at all levels of the gas has not been established, the balance disc two side pressure does not exist, as long as the gas flow, rotor will be along with normal axial force in the opposite direction to move, so double rotor thrust, to prevent accidents.
5, coupling
Because of the characteristics of centrifugal compressor with high speed, high power and rotary operation inevitably have a certain vibration, coupling with both to be able to transfer large torque, but also allows a radial and axial displacement coupling, gear coupling and diaphragm coupling, commonly used are diaphragm type coupling, the coupling does not need lubricant, manufacturing easy.
6. Shell
The casing is also called the cylinder, and the middle and low pressure centrifugal compressor usually adopts the horizontal split face housing, which is advantageous for assembly. The upper and lower housing is positioned by the locating pin, that is, it is connected by bolts. For high pressure centrifugal compressor, cylindrical forging steel casing is used to withstand high pressure. The end cover of this structure is connected by a bolt and a cylindrical shell.
7, diffuser
When the gas flows out of the impeller, it still has a high flow rate. In order to make full use of the velocity energy and increase the pressure of the gas, a diffuser is set up in the rear of the impeller. The diffuser usually has a variety of forms, such as vaneless, blade, straight wall diffuser and so on.
8, curve
Between the intermediate and the grade of the multistage centrifugal compressor, the gas must bend, and the bend is used. The bend is a curved circular space made up of the shell and the baffle.
Advantages and disadvantages of centrifugal air compressor with centrifugal air compressor
9. Reflux
The channel connected behind the bend is the reflux. The function of the reflux is to make the air flow enter the next stage evenly in the required direction. It is made up of baffles and guide vane. The guide vane is usually arc, and can be made into an integral part of the cylinder and can be made separately, and then connected with the bolt.
10, volute
The main purpose of the volute is to collect the gas from the diffuser after the diffuser, or the flow of gas behind the impeller.