Common troubleshooting of the hottest CNG filling

2022-09-21
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Common fault diagnosis and troubleshooting of CNG filling station

the main equipment on the imported CNG filling station, skid mounted compressor station and gas seller, are electromechanical equipment. High degree of automation, safe and reliable work. Generally, this kind of equipment is not equipped with a manual operation system. Once there is a fault, even a small fault, it may bow the protective automatic shutdown of the lifting system and cannot be started manually. Only by mastering the fault diagnosis and troubleshooting technology of these equipment can the fault be eliminated in time, so that the equipment can resume production and ensure the normal operation of the gas station

l, compressor lubrication system

failure of the lubrication system will cause relatively large damage to the compressor. Therefore, for the sake of safety, the control system should make the compressor stop automatically and display the corresponding fault code or fault location. Common faults may include the following situations

the lubricating oil level is too low

the position of the oil level sensor (switch) is too high. When the fault code of low oil level appears, observe whether the oil level in the glass window on the end face of the compressor is above the centerline. Otherwise, the installation position of the oil level switch should be adjusted. If there is a real lack of oil, it should be replenished in time. Pay attention that the oil level should not be lower than the center line

the oil pressure of the lubrication system is too low

the oil filter is too dirty, blocking the oil circuit, and the pressure drop increases, which will reduce the subsequent pipeline oil pressure. Check and clean the oil filter or replace the oil filter element. When the oil circuit system leaks oil, the oil pressure must be reduced. Check whether there is oil leakage at the pipe joint. The failure of the pipeline oil pressure sensor will produce false information. Check whether the pressure sensor is faulty. Improper adjustment of the pressure regulator will also reduce the oil pressure. Check and adjust the position of the oil pressure regulator. The oil pump of lubricating oil system is not working normally, and the oil pressure must be reduced. Check the oil pump. If there is a fault signal of low oil pressure during startup and it cannot be started, if it may be caused by low temperature and high oil viscosity in winter, and the oil pressure cannot be reached in a short time, it can be restored to normal by starting several times. Alternatively, technicians can set the delay working time of the prelubrication pump to be appropriately extended

the cylinder lubrication system is short of oil

the failure of the oil does not flow sensor often produces an error signal, which should be checked or replaced first (most of the time, the battery solidified in the shell is exhausted. It is not like the manufacturer's promised service life of 6-10 years, and it often runs out of power in a few months). Replace the whole assembly during replacement, otherwise problems can still occur. If there are no spare parts around for the time being, two temporary measures can be taken in order not to stop the machine and affect the production on the premise of being sure that the system is not short of oil. Modify the control software so that the computer will no longer temporarily measure the signal. Alternatively, short circuit the two signal wires output by the sensor. Note that this can only solve the urgent need, during which other methods must be often used to monitor the oil circuit. If the plunger pump fails and cannot supply oil to the system, it should be checked, repaired or replaced in time. The lubricating oil distributor slide valve is stuck. It is generally caused by impurities in lubricating oil. Not only should the distributor be disassembled and cleaned, but also the reasons for the unclean lubricating oil should be further clarified, such as the dirty or damaged oil filter. Xinxin should immediately clean or replace the filter element. The starting bursting disc is broken. This is caused by the high oil pressure in the pipeline. First check whether there is oil at several oil outlets of the lubricating oil distributor. Fuyou oil can be caused by the stuck slide valve in the distributor, causing the increase of pipeline oil pressure. After the distributor is disassembled and cleaned and the bursting disc is replaced, HF will return to normal. The one-way valve is busy and cannot be opened, or the oil outlet of the oil tank is blocked by sundries, which makes the suction of the column pump difficult. Relevant parts of Yuyan maintenance

the lubricating oil temperature is too high

the oil cooler is blocked by sundries or dirt, and the cooling efficiency is reduced. Check and allow it to be removed. The failure of the mechanical cold and heat transfer valve (some called static thermal valve) in the oil circuit makes the lubricating oil nifA cool down through the oil cooler. Check and repair or replace the change-over valve. After the filter is dirty and blocked, the oil flow is blocked, the resistance increases, and the oil temperature is wiped out by heating. Clean or replace the oil filter core. If the lubricating oil is too dirty or the viscosity is too high, the friction surface is easy to heat up, and the effect of taking away the heat source to reduce the temperature becomes worse. Replace the appropriate lubricating oil

pre lubrication system failure

the main reason for the reduction of oil pressure is that the viscosity of the lubricating oil is too low or the winter lubricating oil is applied in summer. The lubricating oil with higher viscosity should be replaced. The wear of the pre lubrication pump, the increase of meshing clearance or end face clearance, oil leakage and other faults also reduce the oil pressure. It should be repaired or replaced. The motor of the prelubrication pump does not operate normally. If it is not easy to start, or it does not rotate after running for a while. Most of the pre lubrication pump motors use 110v/220V single-phase motors. When the frequency is 60Hz (50Hz in China's standard), the power selection is just critical. If the load increases slightly, the motor cannot reach the rated speed, the starting winding cannot be separated, so that the torque is reduced and cannot be started, and even the fuel economy of the combustion group can be improved by 5%. We have encountered the same motor and prelubrication pump, the same lubricating oil brand and oil pressure are uncertain, some gas stations can operate normally, and some are difficult to start. It is estimated that the voltage and other factors are slightly different. This kind of situation often occurs when the compressor station is debugged. The solution is to replace the motor with 50Hz power pin

2. The air inlet and exhaust system of the compressor

2.1 the air inlet pressure is too low

the pressure of the gas transmission pipeline is too low, especially when the gas station takes gas from the medium pressure pipeline of the city pipe, which is easy to happen during the peak of gas consumption. When the air pressure of the incoming pipeline is still higher than the minimum inlet pressure of the equipment, the compressor cannot be started, because the setting of the inlet pressure of the compressor is detected by the sensor at the primary inlet of the compressor. The dehydration dryer in front of it still has a pressure drop of about 0.03mpa-o.07mpa. Although the air pressure of the incoming gas transmission pipeline has not reached the lower limit of the set near gas pressure, the air pressure of the compressor population has reached the lower limit, so the compressor is protected and shut down. When this happens, there are three ways to solve it., If the pressure is not too low and is temporary, the lower limit of the intake pressure can be slightly reduced by the juice calculator, and then adjusted back after the pressure is restored; If it is frequent, the pressure of the feedback pressure regulator of the charging tank can be appropriately increased, which should be carried out by experienced personnel, otherwise it will cause other faults; If the pressure of the gas storage cylinder group is high and the vehicle can still be filled with gas, it can be started up after the inlet pressure rises

2.2 the inlet pressure is too high

it is preferred to check whether the reading of the first stage inlet pressure gauge of the compressor (generally set on the outer wall of the skid mounted box) exceeds the maximum inlet pressure. This kind of situation is rare, because the maximum pressure of the pipe has been considered and allowed when selecting the compressor, such as 0.3MPa. If it accidentally exceeds 03mn, but as long as it does not exceed the maximum limit set by the control, such as o.48mpa, there is no problem in short-term operation, which can be ignored. If the maximum limit is exceeded, the compressor will stop automatically and wait for the reduction of pipe pressure. If the limit is exceeded for a long time, a pressure regulator must be added to the incoming pipeline. Check whether the setting of the feedback pressure regulator of the recovery tank is normal (generally about 3 higher than the first stage inlet pressure of the compressor), otherwise the feedback pressure should be appropriately reduced

2.3 the exhaust pressure is too low

check whether the air inlet force is too low. Too low intake pressure will cause the compressor to reach the time of rated exhaust pressure plus, and the temperature rise of the last two cylinders will increase significantly. Check for leaks. The serious leakage of the exhaust pipeline system is a common fault that causes the exhaust pressure to be too low. Check the inlet and exhaust valves of the compressor., If the intake valve is not closed tightly, the intake volume and pressure will be reduced, and the final exhaust pressure will inevitably be reduced or the compression time will be prolonged; If the exhaust valve is not closed tightly, the compressed gas will return to the cylinder during the intake stroke, reducing the air volume and reducing the exhaust pressure. Check whether the air inlet is blocked., The blockage of the intake pipe increases the pressure drop and reduces the intake volume Clean/replace the filter core to reduce the pressure drop in the filter. The pneumatic drain ball valve of the recovery tank is not tightly closed. This will cause the gas discharged from the compressor to continuously enter the recovery tank through the filter, and the pressure of the exhaust pipeline will naturally decrease. The main reason is that the rotating clearance between the pneumatic actuator and the ball valve is too large and cannot be closed in place. It can be normal after the position is adjusted and closed tightly. At this time, open the handle of the oil return valve

2.4 the exhaust pressure is too high

check the valve of the compressor. If it occurs in the intermediate stage, it may be that the opening of the inlet valve of the next stage is not enough, or the exhaust valve is stuck or does not open. Check whether there is blockage in the exhaust pipeline. If the intermediate stage pressure is high, it is estimated that the filter is blocked. If the final exhaust pressure is high, check whether the filter in the pipeline is too dirty and whether the one-way valve and pressure limiting valve are invalid. In particular, it is easy to forget to open the manual ball valve after maintenance. The monitoring and control system fails. When the final exhaust pressure reaches the set value (generally 25MPa), the control system will send a shutdown command. If the control system fails, such as the failure of pressure sensors and other components, the exhaust pressure will continue to rise

2.5 reduce the exhaust volume

check whether there is leakage. First, external leakage, mainly check whether there is a large leakage at all valves (especially safety valves) and pipe joints on the main gas circuit. The compressor valve is not closed tightly. If the inlet valve of a certain stage is not tightly closed, the gas may return to the upper stage through the inlet port when the piston is compressed, which is the reduction of exhaust volume. Check whether the intake pressure is too low. This situation is mostly caused by the reduction of the pressure of the urban gas transmission pipeline during the peak of gas consumption. After the gas transmission pressure recovers, it will be normal. Check whether the motor speed is normal. Most of the motors directly connected with the compressor are asynchronous motors, and the possibility of speed reduction is unlikely. If the motor and compressor are driven by belt, check whether the belt is loose, which affects the speed of the compressor, and adjust the belt tensioner appropriately

2.6 the exhaust temperature is too high

check whether the compressor valve fails. If the compressor valve is not opened enough, the gas flow resistance will increase, the flow rate will increase, and the exhaust temperature will naturally increase. Check the cooling fan. If the cooling fan is driven by belt, check whether the fan belt is too loose, or the belt is broken, so that the fan speed decreases or even stops, and the exhaust gas temperature will inevitably rise. Check the fins of the cooler. This situation is mostly caused by the fact that the radiator is blocked by dust and is too dirty, which reduces the cooling effect

2.7 the output gas has too much oil

clean or replace the stage filter and the last stage coalescing filter The filter is too dirty or damaged, which makes the filter invalid, and the oily gas is discharged without strict filtration. Check whether the automatic discharge process of waste liquid is normal. When the system works normally, the mixture of heavy hydrocarbon and oil condensed in the lower part of the filter will be automatically discharged into the recovery tank at regular intervals. Otherwise, the waste oil will stay in the filter. When the liquid level is higher than the filter element, it must be brought out by gas. Check the oil filling rate of the cylinder lubrication system. The increase of lubricating oil in the cylinder exceeds the standard, so that the amount of oil carried in the gas exceeds the rated value of the filter, and the amount of oil carried in the final discharged gas is bound to exceed the standard

2.8 the pressure of the recovery tank is too high

check whether the pressure relief and discharge valve is not tightly closed. According to the preset, the pressure relief and discharge valve 60rain is opened once for 15s each time If the valve is not closed tightly, the compressed gas discharged by the compressor will continue to

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