Lubricating oil temperature is an indicator of the viscosity and oiliness of lubricating oil. The temperature control of the lubricating oil is too low, the viscosity of the oil increases, and the fluidity is low, which easily causes the oil film of the bearing to oscillate, which poses a greater threat to the smooth operation of the unit. Lubricating oil temperature is too high, oil fluidity is increased, viscosity is reduced, bearing oil film thickness is thinned, experience exchange* operation and maintenance management of synthetic ammonia air compressor Wang Fanqiang (Yunnan Yuntianhua Co., Ltd. Synthetic Workshop, Yunfu 657800, Yunnan) Explain, analyze the causes of the fault and propose a solution to achieve safe and stable operation of the unit.
Ti and maintenance management and unit shutdown during operation have a stable qualitative effect on the ammonia plant under high load.
Spoon maintenance and management system maintenance oil system control as shown.
The new air compressor unit (101-JA) of the ammonia plant of Yunnan Yuntianhua Co., Ltd. is designed and manufactured by MANGHH of Germany and is a motor-driven multi-axis centrifugal compressor. It is designed to meet the needs of process air after 50% increase in ammonia production, and can provide 25% of the total air required for the process system, in parallel with the original air compressor (101-J). As a key equipment to provide important basic raw materials for the production of synthetic ammonia, strengthen the maintenance of the machine, and run the control system of the new air compressor oil system with the white air oil compressor of the first unit. Figure 1) Control of the lubricating oil temperature and Lubricity reduction Wang Fanqiang: The operation and maintenance management of the synthetic ammonia air compressor will reduce the bearing capacity of the oil film, which will affect the safe operation of the unit; if the oil temperature is maintained at a higher temperature for a long time, it may cause carbonization of the lubricating oil, resulting in Decreased lubrication performance. 101-JA should be strictly controlled between 40~45*C after adjusting the oil cooler cooling water return valve in daily operation. The oil tank oil heater should be operated in the automatic position and ensure oil. The temperature control interlock is always in the active state. Pay attention to whether the oil heater can start and stop normally during maintenance inspection to prevent the tank temperature from being too high due to heater failure, which will adversely affect the performance of the oil.
The communication valve between the use and the reserve oil cooler should be kept normally open, and the exhaust valve connected to the fuel tank should be kept at a small opening so that the oil cooler can be switched at any time as needed.
Lubricating oil pressure is a characteristic parameter that guarantees sufficient amount of lubricating oil for the unit. Sufficient lubricating oil can make the compressor rotor form a firm pressure oil film between the journal and the bearing bush at high speed to keep the liquid friction between the two. In addition, the heat generated by the friction is taken away and improved. The working conditions of the bearing (Watt) ensure the smooth operation of the compressor.
Excessive pressure of the lubricating oil entering the bearing will have an impact on the operation of the oil seal: leakage of the lubricating oil and damage to the oil seal may occur, which may have a large impact on the long-term safe operation of the equipment. If the lubricating oil pressure is reduced and the amount of lubricating oil entering the bearing is correspondingly reduced, the heat generated by the friction between the journal and the bearing bush is not easily carried away; at the same time, the pressure oil film required for the liquid friction between the journal and the bearing bush may also be affected. Or difficult to maintain: This may cause burnout of the bearing bush, wear of the seal, and even serious damage to the impeller.
In order to ensure the full supply of the bearing oil of the gears of the gears and the compressors of the 101-JA gearbox, the pressure of the control valve (PI1801B and PI1803B) is adjusted to 0. 15~0.2. Between MPa. The adjustment of the oil supply pressure of the front and rear bearings of the motor should be such that the bearing oil level is maintained at 3/4 of the sight glass. At the same time, it is necessary to prevent the occurrence of full oil level to prevent the lubricating oil from entering the motor. Safe operation has an impact. When adjusting the oil quantity (pressure) of each oil supply point, it should be carried out slowly to avoid the synchronous change of the pressure of other oil supply points, which threatens the safe and stable operation of the unit.
From the outlet of the oil pump to the lubrication point of each bearing of the unit, it is necessary to go through a long pipeline, which will inevitably result in pipeline loss and pressure drop of the oil pressure.
The initial pressure is set to meet the normal oil supply of the unit.
In normal operation, the outlet pressure of the 101JA main oil pump generally needs to be maintained at about 0.55 MPa. The normal value of the oil pressure PI5287 after water cooling and filtration should be 0.4 MPa. If the outlet pressure of the main oil pump is found to have abnormally decreased, Pay attention to check whether the operation of the main oil pump is normal, whether there is leakage of the outlet safety valve, etc.; if the PI5287 is lowered and the outlet pressure of the main oil pump is normal, check whether the PCV-5171 has an internal leak. All kinds of leaks and abnormalities appearing in the oil system must be handled under the premise of ensuring the safety of the unit. If necessary, the system can be shut down after the load is reduced.
Pay attention to the pressure difference of the oil filter during operation. The communication valve between the active and standby should be kept normally open. The oil filter to the fuel tank should be kept at a small opening so that it can be used as needed. The oil filter is switched.
The auxiliary oil pump should always keep the outlet valve fully open, and the start switch is in the *A "position standby state to meet the requirements of the quick start oil supply. Note that the nitrogen pressure of the oil system accumulator should be checked at 0.2. For the operation of the unit to start the oil cycle, the oil circulation should be gradually established according to the oil temperature conditions in strict accordance with the provisions in the unit operation manual to avoid damage to the auxiliary oil pump.
1.2 Compressor and Drive Motor Maintenance Air compressor process flow control diagram is shown.
The total differential pressure of the air filter 102~LA has a direct impact on the consumption of the unit and the amount of intake air of the compressor. Daily maintenance should pay attention to the pressure difference between the filter bag and the filter box. When the pressure difference exceeds 250Pa, it should be replaced in time: Before replacing the filter bag, pay attention to thoroughly clean the air suction filter to extend the replacement filter bag. time. When replacing the filter box, take care to prevent foreign matter from being drawn into the compressor stage.
Before starting the unit, pay attention to open the inlet and return water main valves of the inter-stage cooler, and open the inter-stage trap to discharge. In the operation of the unit, attention should be paid to strengthening the hydrophobic work of the separator between the sections to prevent the inter-stage cooler from generating a high liquid level. The air belt water has an impact on the compressor impeller and damages the unit impeller.
The 101-JA air flow adjustment is regulated by an inlet guide vane mounted in front of the primary impeller. To ensure that no overload occurs during start-up of the unit, the inlet vane opening must be at a minimum position to ensure that the unit is started at low loads.
In normal operation, the working condition of the unit should be controlled by the anti-continent to ensure the oil supply pressure of each bearing. The pump outlet must maintain the surge control deviation value. The CUD is maintained between -2.5 Yunnan Chemical-0.5 to prevent the unit. The operating condition point crossed the anti-surge line of the unit so that the FV1669 suddenly opened or the FIC303 was improperly operated, causing a surge accident in the unit. Pay attention to the change of the inlet flow rate FISC2001S in routine maintenance, and observe and compare the parameters PDI1007, TI1001, PI1005 and other parameters calculated by FISC2001S. In particular, the PDI1007 has a small pressure point and is prone to blockage. When the blockage occurs, the FISC2001S calculation error occurs. The left shift of the unit operating condition point is over the anti-surge line control, causing the FV1669 to suddenly open and cannot be closed.
æ›°Maintenance load adjustment should pay attention to control 101-JA motor working current is not more than 480A. Pay attention to the balance matching of load adjustment between 101-JA and 101-J in system high load (the balance point and tube of the two) The characteristics of the net (air mains pressure) have a close relationship), to avoid the consequences of the surge of 101-JA or the inability to output air normally after the load of the two units is mismatched. For example, when controlling the FIC-3's *A* position, pay special attention to the fact that the FIC-3 increases according to the decrease in the total amount of air (such as the large change in the summer air temperature), so that the *OP* output increases to increase the 101-J load. In this case, according to the characteristics of the parallel operation of the centrifugal compressor unit, the 101-JA outlet flow rate, which is caused by a small amount of gas transmission, is gradually reduced, and the operating condition point is constantly approaching the anti-surge control line, and the FV1669 is opened. It even caused the unit to surge.
In order to prevent the above situation, we should pay close attention to the change of FISC2001D in the operation, and correct the load matching of 101-J and 101-JA according to the value and the load between the 101JA and 101-J units. Eliminate the venting of FV1669 under higher system load.
3) Monitoring of performance of compressors at all levels During routine maintenance, attention should be paid to the inspection records of temperature and pressure of 101JA. Observe whether the differential pressure (air side) of the water coolers of the unit is within the normal range, and the pressure difference appears. Abnormalities should be confirmed and analyzed in a timely manner, and countermeasures should be proposed. During operation, observe the vibration of the unit, the displacement of the shaft, and the change of the oil return temperature of the bearings at all levels. The two inspection points of the same bearing temperature should be observed from time to time. Absolutely limit the bearing temperature (125*C), shaft displacement (*450m), vibration (58m) and other high limits beyond the safe operation during operation, and confirm and analyze the detection points that have obvious changes in time to ensure the safety of the unit. Under the premise of taking appropriate countermeasures, if necessary, stop the 101JA.
New air compressor process control. 3 Maintenance and restart restrictions after shutdown of the unit Whether the unit is faulty or normal, the outlet shut-off valve should be closed in time to prevent the unit from reversing, and the drain of the cooler between the sections is discharged. Whether the oil pump has been started, adjusted and controlled, the TI5218 is about 40C, and the oil circulation is at least 2h before the oil circulation can be stopped according to the situation, and the cooling water is stopped.
For the longer parking time of the unit, the following protective measures should be taken: the compressor cylinder is connected to nitrogen for nitrogen protection, and the oil system is started weekly for oil circulation for at least 2 hours. During the oil circulation, the maintenance personnel must be contacted to manually carry out the unit. Car maintenance.
Every drive to 101JA must strictly follow the following original Wang Fanqiang: Operation and maintenance management of synthetic ammonia air compressor: After the conditions are met, it must be dispatched, the electric instrument can always be approved by the electricity, and then the unit can be started; Start no more than 3 times per hour and no more than 2 hot starts. It is absolutely forbidden to start the unit at will, otherwise it will cause immeasurable impact and loss to the unit and the power supply network.
2 common faults and maintenance of the unit During the operation of the unit, due to various reasons, it will affect the normal operation of the unit, understand and master the common fault phenomena and treatment methods of the unit, and take effective measures in time to reduce the overall system. The extent of the impact is crucial.
2.1 Abnormal opening of anti-surge valve FV1669 In the production, the fluctuation and failure of FV1669 is the most common accident of the unit, and improper operation and instrument control system failure are the main causes of the failure.
2.1.1 FIC303 operation errors occur in operation. It is often caused by lack of understanding and lack of understanding of the main control personnel. When the unit is under load, the indication value of FISC2001D is not enough, which makes FISC2001D0, and the FV1669 suddenly opens. The phenomenon is usually that the inlet guide vane is closed (FIC303), PDI1007 is decreased, and the inlet flow rate FISC2001S is decreased. When this error occurs, first of all, we must be aware of the operational problems. After recovering the output value of FIC303 in time, make FISC2001D<0, and immediately close the small FV1669 according to the negative value to restore the air volume of 101JA.
2) Misplaced 101JA machine screen "FASTOPEN* button When this operation error occurs, the FV1669 can be operated again after the system is limited for 1min. At this time, the main control should immediately reduce the process system load, and can perform the FV1669. After control, immediately turn off the small FV1669 to restore the 101-JA air volume.
2.1.2 Instrument Control System As mentioned above, the inlet flow FISC2001S calculation introduces PDI1007, TI1001, PI1005 and other parameters, wherein the inlet guide vane pressure difference PDI1007 is the most prone to blockage failure. When a fault occurs, the phenomenon is that the inlet guide vane is opened and closed, FISC2001S and PDI1007 are basically unchanged, and the motor current and outlet flow of the unit increase with the opening of the inlet guide vane, at the inlet guide vane opening and motor current. At higher times, the inlet flow and vane pressure difference are lower, which often makes the FV1669 unable to close. For this fault, the pressure guiding pipe should be unblocked by the instrument in time, and if necessary, it should be stopped for a short time.
In the case of this fault, there is usually no fluctuation in the output of FIC303. FISC2001S and PDI1007 will fluctuate or fall. When FISC2001D0 is caused, FV1669 will be abnormally turned on. If the change is not large, you can increase the output of the FIC303 to turn off the FV1669. In severe cases, stop the process and replace the positioner.
When this phenomenon occurs, the FV1669 will suddenly suddenly open completely and cannot be operated. At this time, only the shutdown processing can be taken for the unit, and the positioner or control output card can be replaced. In addition, the deviation between the FV1669 output signal and the valve feedback signal ZI1669 should be noted during the operation of the unit. When the deviation is >10%, the anti-surge system of the unit cannot automatically control the vent valve. When this happens, pay special attention to the FSIC2001D in the operation: When the negative value of this value is small, you need to open FV1669, only manually can be opened. If the unit is in a critical situation such as surge or uncontrollable, emergency stop treatment should be taken to prevent damage to the unit.
3 Conclusion The stable and safe operation of 101-JA is an important basis for the realization of high output and low consumption of ammonia plant. The length of its operation cycle will have a greater impact on the company's economic benefits. In production and maintenance, the safety operation rules of the unit must be strictly followed, and the various process parameters of 101JA should be adjusted and controlled to prevent the fluctuation of the unit and avoid the unit failure, so as to achieve stable and economic operation of the ammonia production unit.
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