Compressor is used to increase gas pressure and transport gas machinery. From the point of view of energy, compressor is a kind of machine that transforms the power energy of prime mover into gas pressure energy. With the development of science and technology, the application of pressure energy is more and more extensive, which makes compressor become one of the essential key equipment in many sectors of national economic construction. In the process of compressor operation, it is inevitable to have some faults or even accidents. Fault refers to the abnormal condition of compressor in operation. Once removed, the compressor can resume normal operation, while accident refers to the damage. The two are often related, if the failure is not eliminated in time, it will cause major accidents.

 

Common faults and their causes and measures

 

Insufficient exhaust volume:

 

The insufficient exhaust volume is compared with the design air volume of the compressor. The following aspects can be considered:

 

1. Failure of air inlet filter: the crud is blocked to reduce the exhaust volume; the suction pipe is too long and the pipe diameter is too small, which causes the increase of suction resistance to affect the air volume, so the filter should be cleaned regularly.

 

2. The decrease of compressor speed reduces the exhaust volume: the air compressor is improperly used, because the exhaust volume of the air compressor is designed according to certain altitude, suction temperature and humidity. When it is used on a plateau that exceeds the above standards, the suction pressure will be reduced, and the exhaust volume will be reduced.

 

3. The cylinder, piston and piston ring are seriously worn and out of tolerance, which makes the clearance and leakage increase, and affects the exhaust volume. In case of normal grinding, the wearing parts, such as piston rings, shall be replaced in time. If the installation is not correct and the clearance is not appropriate, it shall be corrected according to the drawing. If there is no drawing, experience data can be taken. For the clearance between piston and cylinder along the circumference, if it is cast iron piston, the clearance value is cylinder diameter zero point zero six ／100～ zero point zero nine / 100; for aluminum alloy piston, the clearance is zero point one two ／100～ zero point one eight / 100; steel piston can be made of aluminum alloy piston Smaller value.

 

4. Air leakage caused by lax stuffing box reduces air volume. The first reason is that the stuffing box itself is not in conformity with the requirements when it is manufactured; the second reason may be that the center of the piston rod and the stuffing box is not well aligned during installation, resulting in wear and tear and air leakage; generally, the stuffing box is filled with lubricating oil, which plays the role of lubrication, sealing and cooling.

 

5. The influence of compressor suction and discharge valve failure on discharge capacity. Metal chips or other sundries fall between the valve seat and the valve disc, which are not closed tightly, forming air leakage. This not only affects the exhaust volume, but also affects the change of the interstage pressure and temperature. The loose contact between the valve seat and the valve plate causes air leakage, which affects the exhaust volume. One is the manufacturing quality problem, such as the valve plate warping, and the other is the air leakage caused by the severe wear between the valve seat and the valve plate.

 

6. The spring force of the air valve does not match the air force well. Too strong elastic force will slow the opening of the valve plate, too weak elastic force will delay the closing of the valve plate, which will not only affect the gas volume, but also affect the increase of power, as well as the life of the valve plate and spring of the gas valve. At the same time, it also affects the change of gas pressure and temperature.

 

7. The pressing force of pressing air valve is improper. If the compression force is small, the valve cover will be deformed and damaged. Generally, the compression force can be calculated by the following formula: P = k π / 4 d2p2, D is the valve chamber diameter, P2 is the maximum gas pressure, K is the value greater than 1, generally, it is taken as One point five ~ Two point five , k = at low pressure One point five ~ Two , k = at high pressure One point five ~ Two point five 。 Taking K in this way is proved to be good in practice. If the air valve fails, the valve cover will inevitably heat up and the pressure will not be normal.

 

Exhaust temperature not OK

 

Abnormal exhaust temperature means that it is higher than the design value. Theoretically, the factors that affect the increase of exhaust temperature are: intake temperature, pressure ratio, and compression index (for air compression index k =) One point four ）。 The actual situation affects the factors of high suction temperature, such as: low intermediate cooling efficiency, or the scale in the intercooler will affect the heat exchange, then the suction temperature of the later stage must be high, and the exhaust temperature will also be high. The leakage of air valve and piston ring not only affects the rise of exhaust temperature, but also changes the interstage pressure. As long as the pressure ratio is higher than the normal value, the exhaust temperature will rise. In addition, water-cooled machines, lack of water or water will make the exhaust temperature rise.

 

Abnormal pressure and reduced exhaust pressure

 

If the air volume discharged by the compressor cannot meet the flow requirements of the user under the rated pressure, the exhaust pressure must be reduced. The reduction of the required exhaust pressure is a phenomenon, whose essence is that the exhaust volume cannot meet the user's requirements. At this time, we have to change another machine with the same exhaust pressure and large exhaust volume. The main reason for the abnormal interstage pressure is the air leakage of the air valve or the air leakage after the wear of the piston ring, so we should find out the reasons and take measures from these aspects.

 

Abnormal noise

 

If some parts of the compressor fail, it will make abnormal noise. Generally speaking, the operator can identify the abnormal noise. The clearance between the piston and the cylinder head is too small, and it directly impacts; the connecting nut between the piston rod and the piston is loose or tripped, the plug on the end face of the piston is cypress, the piston moves upward in series and collides with the cylinder head, the metal fragments falling into the cylinder and the water accumulated in the cylinder can make knocking sound in the cylinder. In the crankcase, the bolts, nuts, connecting rod bolts, crosshead bolts are loose, trip, broken, etc., the shaft diameter is seriously worn, the clearance is increased, the clearance between crosshead pin and bushing is too large or seriously worn, etc., which can cause impact in the crankcase