Common failures of cold storage compressors and on-site countermeasures

Common failures of cold storage compressors and on-site countermeasures

The cold storage compressor is a machine used to increase gas pressure and transport gas. From the energy point of view, the cold storage compressor is a machine that converts the power energy of the prime mover into gas pressure energy. With the development of science and technology, the application of pressure energy has become increasingly widespread, making cold storage compressors one of the essential key equipment in many sectors of the national economy. During the operation of the cold storage compressor, some failures and even accidents will inevitably occur. Failure refers to an abnormal situation in the operation of the cold storage compressor. Once the cold storage compressor is removed, normal operation can be restored, while an accident refers to a damage situation. The two are often related, and if the fault is not eliminated in time, it will cause a major accident.

　　Common failures and their causes and measures

　　 1. Insufficient displacement: Insufficient displacement is compared with the design capacity of the cold storage compressor. Mainly can be considered from the following aspects:

　　1. Malfunction of the intake filter: fouling and clogging, which reduces the exhaust; the intake pipe is too long and the pipe diameter is too small, resulting in an increase in the intake resistance and affecting the air volume. The filter must be cleaned regularly.

2. The reduced speed of the cold storage compressor reduces the displacement: the compressor of the air cold storage is used improperly. Because the displacement of the air cold storage compressor is designed according to a certain altitude, suction temperature and humidity, when it is used in excess When the above-mentioned standard plateau is reached, the suction pressure decreases, and the exhaust volume will inevitably decrease.

　　3. The cylinder, piston, and piston ring are seriously worn and out of tolerance, which increases the clearance and leakage, which affects the displacement. When it belongs to normal grinding, the wearing parts, such as piston rings, must be replaced in time. If the installation is incorrect and the gap is not appropriate, it should be corrected according to the drawings. If there is no drawing, experience data can be taken. For the gap between the piston and the cylinder along the circumference, if it is a cast iron piston, the gap value is the diameter of the cylinder 0.06/100～0.09/100; For aluminum alloy pistons, the gap is 0.12/100～0.18/100 of the air diameter; steel pistons can take the smaller value of aluminum alloy pistons.

　　4. The stuffing box is not tight and leaks and reduces the gas volume. The reason is that the stuffing box itself does not meet the requirements when it is manufactured; secondly, it may be due to poor alignment of the piston rod and the center of the stuffing box during installation, resulting in wear, strain, etc., causing air leakage; generally lubricating oil is added to the stuffing box , It plays a role of lubrication, sealing and cooling.

　　 5. The influence of the failure of the suction and discharge valves of the cold storage compressor on the displacement. Metal fragments or other debris fall between the valve seat and the valve plate, and the closing is not tight, resulting in air leakage. This not only affects the exhaust volume, but also affects the changes in the pressure and temperature of the interstage; the lack of contact between the valve seat and the valve plate causes air leakage and affects the exhaust volume. One is the manufacturing quality problem, such as valve plate warpage, etc. The second is due to the serious wear of the valve seat and the valve plate, resulting in air leakage.

　　6. The spring force of the gas valve is not well matched with the gas force. If the elastic force is too strong, the valve plate will open slowly, and if the elastic force is too weak, the valve plate will not close in time. This not only affects the air volume, but also affects the increase in power and the life of the valve plate and spring. At the same time, it will also affect the changes in gas pressure and temperature.

　　 7. The compression force of the compression valve is improper. If the pressing force is small, the air will leak. Of course, too tight will not work, and the valve cover will be deformed and damaged. The general pressing force can be calculated by the following formula: p=kπ/4, D2P2, D is the diameter of the valve cavity, and P2 is z *For large gas pressure, K is a value greater than 1, generally 1.5～2.5, K=1.5～2.0 at low pressure, K=1.5～2.5 at high pressure. It is good to take K in this way. If the valve fails, the valve cover will inevitably heat up, and the pressure will be abnormal.

　　 2. The exhaust temperature is abnormal

Abnormal exhaust temperature means that it is higher than the design value. In theory, the factors that affect the increase in exhaust temperature are: intake air temperature, pressure ratio, and compression index (for air compression index K=1.4). The actual situation affects the high suction temperature factors such as: low intercooling efficiency, or excessive scale formation in the intercooler affects heat exchange, then the suction temperature of the subsequent stage must be high, and the exhaust temperature will also be high. The valve leaks and the piston ring leaks, which not only affects the increase in exhaust temperature, but also changes the pressure between stages. 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 insufficient water will increase the exhaust temperature.

　　 3. Abnormal pressure and decrease of exhaust pressure

The air volume discharged by the cold storage compressor cannot meet the user's flow requirements under the rated pressure, and the exhaust pressure must be reduced. The reduction in the required exhaust pressure is a phenomenon, and the essence is that the exhaust volume cannot meet the user's requirements. At this time, I had to change to another machine with the same exhaust pressure and large exhaust capacity. The main reason for the abnormal interstage pressure is the air valve leakage or the air leakage after the piston ring is worn. Therefore, the reasons should be found and measures should be taken from these aspects.

　　 Four, abnormal noise

If some parts of the cold storage compressor fail, it will make an abnormal sound. Generally speaking, the operator can distinguish the abnormal sound. The gap between the piston and the cylinder head is too small and directly impacts; the piston rod and the piston connecting nut are loose or tripped, the piston end is blocked by the thread, the piston moves upward and collides with the cylinder head, metal fragments fall into the cylinder, and water accumulates in the cylinder. Both can emit percussive sound in the cylinder. Crankshaft bolts, nuts, connecting rod bolts, cross head bolts in the crankcase are loose, tripped, broken, etc., the shaft diameter is severely worn, the gap increases, the cross head pin and the bushing match the gap is too large or the wear is serious, etc. There was a crash sound in the crankcase. The exhaust valve piece is broken, the valve spring is loose or damaged, the load regulator is adjusted improperly, etc., can make a knocking sound in the valve cavity. From here to find the fault and take measures.

　　 5. Overheating failure

Where the friction between crankshaft and bearing, crosshead and sliding plate, filler and piston rod, etc., the temperature exceeds the specified value, it is called overheating. The consequences of overheating: One is to accelerate the wear between the friction pairs, and the other is that the heat of overheating continues to accumulate until the friction surface is burned and the friction surface is burned, causing a major machine accident. The main reasons for bearing overheating are: uneven fitting of bearing and journal or too small contact area; bearing deflection and crankshaft bending and twisting; lubricating oil viscosity is too small, the oil circuit is blocked, the oil pump is faulty and the oil is cut off, etc.; during installation There is no leveling, no gap is found, the main shaft and the motor shaft are not aligned, the two shafts are tilted, etc.

　　 The above content is organized based on the problems encountered by the students in their actual work for reference. If you have any problems, please communicate and correct them in time.