I、 What are the characteristics of a centrifugal compressor?

Centrifugal compressor is a kind of turbine compressor, with large air flow rate, small volume, simple structure, stable operation, convenient maintenance and gas is not polluted by oil, various drive mode and other characteristics.

 

II 、The working principle of centrifugal compressor?

Generally speaking, the main goal to increase gas pressure is to increase the number of gas molecules in a unit volume, which is to shorten the distance between the gas molecules and molecules, in order to achieve this goal, adopt the method of gas dynamics, namely using the mechanical work components (high-speed rotating impeller), for gas work, make the gas under the action of the centrifugal stress, At the same time, the kinetic energy is also greatly increased, and then in the diffuser passage this part of kinetic energy is transformed into static pressure energy, so that the gas pressure is further increased, this is the working principle of centrifugal compressor.

 

III、what are the common prime movers of centrifugal compressor?

Centrifugal compressor common prime mover: motor, steam turbine, gas turbine and so on.

 

IV、 what are the auxiliary equipment of centrifugal compressor?

The operation of the main engine of the centrifugal compressor is based on the normal operation of the auxiliary equipment, which includes the following aspects:

1. Lubricating oil system

2. Cooling system

3. Condensate system

4. The electrical instrument system which is also called the control system

5. Dry gas sealing system

 

V、which types can centrifugal compressor be divided according to the structural characteristics ?

Centrifugal compressors can be divided into horizontal split type, vertical split type, isothermal compression, combined type and so on.

 

VI、 What are rotor composed of?

The rotor includes a spindle, a impeller, a shaft sleeve, a shaft nut, a spacer, a balance disc and a thrust disc.

 

VII、 the definition of level?

Stage is the basic unit of centrifugal compressor, which is composed of a impeller and a group of fixed elements with which to cooperate.

 

VIII、 Definition of paragraph?

The stage between each intake port and the exhaust port constitutes a section, which is composed of one or more stages.

 

IX、, the definition of cylinder?

The cylinder of the centrifugal compressor is composed of one or several sections. A cylinder can accommodate at least one stage and up to ten stages.

 

X、Definition of columns?

High-pressure centrifugal compressor sometimes need is composed of two or more than two cylinders, consists of a cylinder or a few cylinders are arranged in a axis as the columns of the centrifugal compressor, different columns, different speed, the speed of the high pressure column is higher than the low pressure column and column of the same speed (coaxial), high pressure, impeller diameter greater than the low pressure column.

 

XI、What is the role of the impeller? What types are there according to the structural features?

Centrifugal compressor impeller is the only element of gas medium work, gas medium under the centrifugal force of high-speed rotating impeller, with the impeller rotating operation, in order to gain momentum, and the diffuser can be partly converted into pressure, under the action of centrifugal force, out of impeller mouth to jilt, diffuser, corner impeller further pressure, backflow into the next level, Until discharged from the compressor outlet.

Impeller according to the structural characteristics can be divided into: open, half open, closed 3 types.

 

XII、What is the maximum flow condition of the centrifugal compressor?

When the flow reaches the maximum, it is the maximum flow condition. There are two possible causes for this condition:

 

First, the flow at the throat of a flow channel reaches a critical state, when the volume flow of gas is the maximum, let the back pressure of the compressor and then reduce, the flow is impossible to increase, this kind of working condition has also become a blocking condition.

 

Second, flow passage has not met the maximum critical state, which does not appear blocking condition, but the compressor under large flow, the internal flow loss is very big, can offer the exhaust pressure is very small, almost close to zero energy, only can be used to overcome the resistance of the exhaust pipe to maintain such a large flow, this is the maximum flow centrifugal compressor working condition.

 

XIII、 what is the surge of centrifugal compressor?

Centrifugal compressor in the process of production and operation, sometimes suddenly produce strong vibration, gas medium flow and pressure also appear large pulsation, accompanied by periodic and heavy cry, and air flow fluctuations in the pipe network caused by wheezing strong noise, this phenomenon becomes the surge condition of centrifugal compressor.

The compressor cannot run for a long time under surge condition. Once the compressor enters surge condition, the operator should immediately adopt adjustment measures to reduce the outlet pressure, or increase the inlet or outlet flow, so that the compressor can quickly escape from the surge area and realize the stable operation of the compressor.

 

XIV、What are the characteristics of surge phenomenon?

Once the surge phenomenon occurs in the centrifugal compressor, the operation of the unit and the pipe network has the following characteristics:

1. The outlet pressure and inlet flow rate of the gas medium vary greatly, and sometimes gas backflow phenomenon may occur. The gas medium is discharged from the compressor to flow to the inlet, which is a dangerous condition.

2. The pipe network has periodic vibration, large amplitude, low frequency, and accompanied by periodic roar

3. Compressor body vibration is strong, housing, bearing have strong vibration, and emit strong periodic air flow sound, because of strong vibration, bearing lubrication conditions will be destroyed, bearing bush will burn, or even the shaft is broken, the rotor and stator will produce friction, collision, sealing elements will be seriously damaged.

 

XV、 how to carry out anti-surge adjustment?

Surge harm is great, but so far can not be eliminated from the design, can only try to avoid the unit in operation into the surge condition, the principle of anti-surge is aimed at the cause of surge, in the surge will occur, immediately try to increase the compressor flow, so that the unit out of the surge zone. There are three specific ways to prevent surge:

1. Part of the air defense law.

2. Partial gas reflux method

3. Change the compressor running speed

 

XVI、Why is the compressor running below the surge limit?

1. Outlet back pressure is too high

2. Inlet line valve is throttled

3. Outlet pipeline valve is throttled

4. The anti-surge valve is defective or incorrectly adjusted

 

XVII、What are the working condition adjustment methods of centrifugal compressor?

Due to the inevitable change of process parameters in production, it is often necessary to adjust the compressor manually or automatically, so that the compressor can adapt to the production requirements and operate under variable working conditions, so as to maintain the stability of the production system.

There are generally two kinds of centrifugal compressor regulation: one is equal pressure regulation, that is, in the back pressure under the premise of constant flow regulation; The other is equal flow regulation, that is, in the case of ensuring the constant flow to adjust the exhaust pressure of the compressor, specifically, there are the following five types of regulation:

1. Outlet flow regulation

2. Inlet flow regulation

3. Change the speed adjustment

4. Rotate inlet guide vane for adjustment

5. Partial air defense or reflux regulation

 

XVIII、 How does the speed affect the performance of the compressor?

The speed of the compressor has the function of changing the performance curve of the compressor, but the efficiency is constant, so it is the best form of compressor adjustment method.

 

XIX、 What is the meaning of equal pressure regulation, equal flow regulation and proportional regulation?

1. Equal pressure adjustment refers to keeping the exhaust pressure of the compressor unchanged and only changing the gas flow adjustment.

2. Equal flow regulation refers to keeping the flow of the compressor conveying gas medium unchanged, but changing the regulation of the discharge gas pressure.

3. Proportional adjustment refers to the adjustment that keeps the pressure ratio unchanged (such as anti-surge adjustment) or the volume flow percentage of the two gas media unchanged.

 

XX、What is pipe net? What are its components?

The pipe net is the pipeline system of the centrifugal compressor to realize the gas medium transportation task. It is located before the compressor inlet to become the suction pipe, and after the compressor outlet to become the discharge pipe. The sum of the suction and discharge pipe is usually called the pipe network.

Pipe netw is generally composed of pipelines, pipe fittings, valves and equipment.