Start-up and shutdown of reciprocating compressors

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I. Starting a reciprocating compressor: 1. Preparation work: A. The installation personnel check whether all components of the main unit have been installed properly, and ensure that the clearances between all moving parts meet the required standards. B. Notify the electrician to check whether the motor insulation (above 0.4 M) and the electrical switches meet the technical requirements; notify the instrument technician to check whether the measuring instruments and control/protection devices also meet the technical requirements. C. Clean the area, removing all dust and oil from the surfaces of the equipment and workbenches. D. Inspect or clean the circulating oil system (including the oil tank, crankcase, oil pump, filters, cooler, oil pipes, valves, and oil circuits for moving parts). In particular, the iron shavings and hard debris in the oil circuit system should be thoroughly cleaned out. After thorough cleaning, pour fresh lubricating oil into the tank, start the oil pump, and check its operation as well as for any leaks in the oil circuit (the oil pressure must not be lower than 0.25 MPa). E. Inspect or clean the oiler to ensure it operates properly, that the oil passages are unobstructed, there are no leakage points, the oil flow rate is appropriate (10 drops/minute), and the oil quality is clean. F. Open the main cooling water valve, as well as the inlet and outlet valves for the cooling water in the cylinder water jackets, packing, and oil cooler; check whether the water pressure, quality, and flow rate meet the requirements. 2. Testing steps: A. Open the cooling water valve and adjust the water flow. B. Start the circulating oil pump, adjust the oil pressure to above 0.25 MPa, and check whether the pressures at all pressure measurement points are the same (including springs, pressure gauges, electrical contacts, and pressure relays). Apply sufficient lubricant to all friction surfaces of the transmission mechanisms, then stop the pump. C. Manually operate or start the oil injection pump to fill the cylinder with an adequate amount of lubricating oil, then stop the pump. D. Spin the shaft several times to form a layer of lubricating oil film on all the friction surfaces and the cylinder wall surfaces. (When using the cranking mechanism to crank the engine, first move the handle to the cranking position before starting the cranking motor. Run it for 3–5 minutes; there should be no dead points when cranking in either direction, and the cranking mechanism must be sensitive and reliable.) Then switch the barring gear to the starting position and stop the barring gear motor. ) E. Notify the main substation by phone to supply power to the host. F. Start the circulating oil pump, oil injection system, and circulating fan. G. Starting Host 3, Precautions for Starting the Machine: 1. Do not turn the machine while under pressure. 2. The increase in pressure and dosage must be gradual. 3. Operate the valves slowly, without haste, and pay close attention to changes in current. II. Precautions for normal shutdown: 1. Shutdown is prohibited when there is pressure remaining (the gauge pressure in each section has not been reduced to zero). 2. The circuit valves at all levels should not be opened too quickly or to a full extent, in order to prevent backflow of gas and liquid. 3. The main unit must be shut down first, followed by the auxiliary unit. III. Ten common faults and their troubleshooting
1. Unusual noises from the crankcase
Causes: (1) Loose crosshead pins or crosshead pin covers ； (2) Wear or looseness of the main shaft bearings, crosshead bearings, and connecting rod bearings ； (3) Low oil pressure ； (4) Low oil temperature ； (5) Incorrect oil type ； (6) Cylinder noise. Exclude: (1) Check whether the crosshead pin and crosshead pin cover are loose; tighten any loose components ； (2) Check the clearances of the main shaft bearings, crosshead bearings, and crosshead shaft bearings to see if they are worn or loose; tighten or replace the components as necessary ； (3) Check whether the oil pressure is low and for any leaks; increase the oil pressure and repair the leaks ； (4) Check whether the oil temperature is too low; increase the oil temperature under loading conditions, and reduce the flow rate of cooling water to the oil thermostat ； (5) Check whether the oil type is correct; replace any incorrect oil ； (6) Check whether the piston nut is loose and tighten it. Fault 2: The compressor will not start. Cause: (1) Drive motor failure ； (2) Startup disk switch failure ； (3) Hydraulic start switch malfunction ； (4) Control panel failure ； (5) Excessively high pressure in the cylinder ； (6) The starting device is locked. Exclude: (1) Check whether there is a fault with the drive motor, and readjust the power ； (2) Check the circuit ； (3) Check the oil pressure, adjust or replace the switch ； (4) Check the circuit connections and settings of the control panel ； (5) Adjust the pressure inside the cylinder to the normal value ； (6) Check whether the starting device is locked, and release the lock. Fault 3: Crankshaft oil seal leakage. Cause: (1) Incorrect installation of the oil seal ； (2) Oil drain hole is clogged. Exclusion: (1) Reinstall the oil seal according to the inspection standards ； (2) Clean the oil seal drain hole to remove any blockages. Fault 4: Oil wiper leakage. Cause: (1) Wear of the oil wiper ring ； (2) Oil scraper ring is installed incorrectly ； (3) Piston rod wear or scratches ； (4) Incorrect ring side clearance. Exclude: (1) Replacing the oil scraper ring ； (2) Check whether the oil scraper ring is installed correctly; install it according to the inspection standards ； (3) Repair or replace the piston rod ； (4) Replace the piston rings and backup rings. Fault 5: Low oil pressure. Cause: (1) Air entrainment in the oil pump ； (2) The rotating part slaps the oil surface to create foam ； (3) Low oil temperature ； (4) The oil filter is dirty ； (5) Loss of machine lubricant ； (6) Excessive leakage from main bearings ； (7) The pressure setting of the pressure regulating valve is too low ； (8) Oil pressure gauge failure ； (9) Failure of the oil pressure control valve ； (10) The oil tank inlet is blocked. Exclusions: (1) Repairing or replacing a worn-out oil pump ； (2) Lower the oil level in the oil tank ； (3) Use a crankcase immersion heater or electric heat tracing for heating ； (4) Clean the oil filter or replace the filter element ； (5) Check the oil circuit ； (6) Adjust the main bearing clearance ； (7) Reset the pressure of the pressure regulating valve ； (8) Replace the oil pressure gauge ； (9) Adjust, repair, or replace the oil pressure control valve ； (10) Clean the inlet pipe of the oil tank. Fault 6: Abnormal noise inside the cylinder. Cause: (1) Loose piston ； (2) Piston impacts the outer end or inner end ； (3) Crosshead lock nut is loose ； (4) Air valve leakage or damage ； (5) Damaged piston rings ； (6) The valve sealing air cushion is damaged. Exclude: (1) Check whether the piston nut is loose; tighten any loose nuts ； (2) Check the clearance at the outer or inner end of the piston, and adjust it to the correct position ； (3) Tighten the crosshead lock nut ； (4) Check whether the air valve has any leaks or damage; repair or replace the valve ； (5) Replace damaged piston rings ； (6) Replace the sealing air cushion. Fault 7: Excessive seal overheating. Cause: (1) Lubrication failure ； (2) The lubricating oil fails to meet the standards or the amount of oil is insufficient ； (3) Insufficient cooling water (especially for water-cooled gaskets) ； (4) Incorrect gap. Exclusions: (1) Replacing the lubricating oil check valve or lubricating oil pump ； (2) Use qualified lubricating oil and increase the amount of lubricant ； (3) Reduce the cooling water inlet temperature ； (4) Adjust the gap. Fault 8: Packing leakage. Causes: (1) Packing wear ； (2) Lubricating oil is substandard or the oil level is low ； (3) Dirty packing ； (4) Excessive rapid increase in pressure ； (5) The packing is not installed correctly ； (6) Incorrect opening or side gap ； (7) Packing drain plug ； (8) Scratches on piston rod ； (9) The roundness of the piston rod is out of tolerance. Exclude: (1) Replacing the gasket ； (2) Replace with qualified lubricant and increase the amount of lubricant ； (3) Clean the packing box and pipelines ； (4) Reduce the pressure increase gradient ； (5) Install the gasket correctly in accordance with the inspection standards ； (6) Check and adjust the clearance ； (7) Check that the packing drain is open to allow drainage at the lowest point ； (8) Repair or replace the piston rod ； (9) Adjust the crosshead gasket to the appropriate position to reduce the roundness error of the piston rod. Fault 9: Excessive carbon buildup on the valve. Cause: (1) Too much lubricant in the cylinder ； (2) Cylinder lubricating oil failed inspection ； (3) Carbon carried by oil coming from the import or supply source ； (4) Valve leakage or damage, resulting in high temperatures ； (5) Excessive pressure gradient in the cylinder, high temperature. Exclude: (1) Reduce fuel supply ； (2) Use qualified lubricating oil ； (3) Install a filtration separator or waste discharge system ； (4) Repair or replace the valve assembly ； (5) Inspect the air valves inside the cylinder and clean the water jacket. Fault 10: High exhaust temperature. Cause: (1) Intake valve leakage ； (2) Exhaust valve or piston ring leakage ； (3) High intake air temperature ； (4) Blockage of water in the water tank jacket ； (5) The cylinder lubricating oil fails the quality check or the flow rate is insufficient. Exclude: (1) Repairing or replacing the faulty intake valve or piston rings ； (2) Repair or replace the intake valve or piston rings ； (3) Clean the air cooler ； (4) Clean the cylinder water jacket ； (5) Use qualified lubricant and the correct flow rate.