Listen to the voice of common equipment running situation of discrimination, this is mainly due to vibration or noise in the operation of the equipment is a sign of some abnormal happens, therefore, by listening to the sound, for some equipment situation can check-up, identify whether failure.
First,Abnormal noise of rotating equipment
Common causes of noise are as follows:
►Internal component corrosion of the valve;
►Pump vacuuming;
►High power pump low load operation;
►The surge of centrifugal compressor;
►The partition of the heat exchanger is broken;
►The noise of the one-way valve;
►The scream of control;
►The steam line is hit by water.
1. Compressor
The noise of the compressor is divided into the noise of the centrifugal compressor and piston compressor, mainly by the host of aerodynamic noise and auxiliary machinery noise, generally measured noise at ordinary times is 84 ~ 102 decibels.
► Centrifugal compressor noise.
When the centrifugal compressor is surging, it will periodically send out a deep and roaring noise every few seconds. At this point, the compressor has been in a state of flux, the rotor reciprocating sliding between the bearings, and thrust bearings, rotor of the horizontal movement will inevitably damage the compressor shaft seal.
Every surge shows once again the sliding between the rotor in the bearing, the higher the surge of voice, rotor horizontal effect is stronger, the more dangerous, will cause the light surge to the compressor completely destroy itself.
Generally speaking, a machine can rotate more than 8000r/min at 3000r/min to prevent surge.
Causes of surge and remedies:
A, the discharge pressure is too high.
Empty the receiver of the compressor rear cooler to reduce the pressure, or open the cooling water valve in the rear cooler.
B. Low pumping rate.
Open the anti - surge, allowing the gas to be released back to the back of the compressor.
C. High temperature of inhalation gas.
Most of the devices are equipped with upstream into a small amount of light in the compressor suction liquid hydrocarbons, liquid evaporation cooling stream of suction compressor, may also ask the upstream process to reduce the gas temperature entering the compressor.
►Noise from piston compressor.
The noise and vibration of the piston compressor are mainly mechanical, and the oil and water entering the cylinder also produce noise due to the untimely discharge of the process.
A, air valve of cutting piece and spring if fracture, on the one hand, will cause the compressor exit pressure and temperature change, at the same time, we used to hear when they listen to great damage to the valve hissing sound.
B. If the clearance between the rotating parts of the compressor is not appropriate, such as the gap between the crosshead, big head tile and small head tile is too large or too small, the compressor will make a boom when it turns.
C, the compressor cylinder inside fell into some mechanical impurity, or the clearance between the piston and cylinder head is too small, the compressor in turns cylinder will "dangdang" clattering metal sound, the sound should immediately stop overhaul. Otherwise, major equipment damage will occur.
D, because the process sewage is not timely, oil and water into the cylinder liquid collision occurs, the liquid impact sound is the sound of "product", then we should strengthen drainage, fluid serious when parking and maintenance.
Some chemical plants have had the air valve broken into the cylinder, the piston and the cylinder head damaged production accident. Therefore, in the production practice, we can judge whether the compressor operates normally according to the different sound produced by compression.
2. Pump
Noise is the main source of the motor and pump and motor noise is itself the electromagnetic vibration of electric magnetic noise, air dynamic noise and mechanical noise caused by the tail fan of three parts. It's usually 83 to 105 decibels.
The abnormal noise and vibration of the pump are mainly caused by pump pumping, too large pump capacity and cavitation of the pump.
► For pump time
Centrifugal pump vibration sound because of time, it shows that the suction pressure was not enough to prevent the vaporization of liquid inside the pump, when the bubble deformation and breakage caused by vibration, if the time continues, pump shaft seals, bearing and impeller are subject to damage.
Stop the pump to the fastest method is to export throttling of the pump to reduce flow velocity, and then improve the spare tank of liquid level of the pump, and stop the pump directly, the best thing to do is to pump and pumped liquid tank for interlock.
► Pump cavitation
The noise and vibration produced by cavitation happen. Under the repeated action of huge impact force, the surface fatigue of impeller starts from pitting to form a serious honeycomb cavity, which causes impeller damage.
In addition, when the cavitation is serious, a large number of bubbles occupy part of the space of the liquid channel, resulting in a drop in the flow pressure head and efficiency of the pump. Therefore, in order to make the pump run normally, the minimum pressure of the impeller inlet must be maintained at a critical value, and the lowest pressure should be greater than the saturated vapor pressure of the liquid under the transmission temperature. When the cavitation occurs in the actual operation, the pump should be discharged immediately and the gas inside is discharged.
► The pump capacity is too large.
Large capacity pump in reducing capacity, operation process will often make low and dumb voice, this is mainly due to the impeller inside the internal circulation caused by the long term, this will make the impeller is damaged, the only way is to increase the flow of exports.
For any rotating equipment with excessive vibration, its work should be stopped immediately before the pump is damaged.
Second, valves and piping abnormal noise and vibration
The noise of the valve and pipe is mainly the noise of the friction line with the pressure gas, or the disturbance of the surrounding gas caused by the sudden depressurization.The noise of the valve is mainly due to the following reasons:
1, the noise produced by the vibration of the check valve;
2, the seat falls into the foreign body;
3. The high speed liquid makes the valve damaged.
4. The switch valve is used as a control valve.
5. Leakage of gate valve.
► Have a check valve noise due to vibration
Mainly from the lift check valve in general, compressor and pump outlet safety check valve, its purpose is to prevent the high pressure gas and liquid system in compressor and pump.
Gas compressor discharge is fluctuating, it will cause the outlet check valve spool irregular motion in the body, it will produce a lot of noise, the guide sleeve will wear long check valve, serious when the guide sleeve will rupture, serious impact on production.
In production practice, the outlet of the compressor with a swing check valve can basically overcome the noise produced by the pulsation of the compressor air flow.
Some chemical plants have succeeded in remaking the exit check valves of the transformation compressor to completely eliminate the vibration and noise of the check valves.
Another case of noise produced by check valves is that the pressure difference before and after check valves is relatively large, which is also encountered in actual production.
When the front and back pressure difference of the check valve is more than 0.5 kilograms, the hydrogen making check valve vibrates very badly and makes a sound metal touching the metal.
It is found that the wear of the guide sleeve of the check valve is very serious and seriously affects the long period operation of the device when the hydrogen production check valve is overhauled. If the check valve is changed into a program control valve, this problem can be basically solved.
► The scream of the control valve
The picture shows the pump control valve.
The control valve in good condition should be able to shut normally. When the control valve is completely closed, it will make a dull noise, which means that the liquid leaks through controlling the valve seat. If the pressure drop of the valve is larger, the noise can be very high. A small stone, screw, slag, etc. can be stuck on the valve to make the valve close.
Noise indicates that a high speed fluid flows through the valve. If it goes on for a long time, it will wear the valve body. If the valve can not be removed and repaired, the best way is to reduce the pressure of the upstream pipeline.
If the normal working position of the control valve is closed, it often produces noise, and the pressure drop through the valve is very large. When the gas liquid mixture throttled through the control valve, it will generate vibration. If the temperature of the fluid is reduced, the vibration will decrease.
Source: chemical 707;
The official public, WeChat ID.
苏公网安备 32011402010684号 |
苏ICP备15029307号-1
