Let’s go with a compressor oil circulation scheme! Thank you all

1.7.1 Oil circulation flushing of the lubricating oil system 1.7.1.1 Preparatory work before oil transfer (1) All lubricating oil pipelines and valves shall be pickled, passivated, and air-dried (especially various branch lubricating oil pipelines, turbine control oil pipelines, oil inlet and outlet pipelines of the high-level oil tank, and valve assemblies), after which the flanges shall be covered with clean plastic sheeting. (2) Clean the interior of the fuel station’s fuel tanks, filters, high-level fuel tanks, and engine bearing housings with flour. (3) Clean the oil cooler with water and let it air dry; if a core pull inspection shows it to be clean, this step can be skipped. (4) The acid cleaning, passivation, and cleaning of the oil system must be inspected simultaneously by the owner, the construction party, and the supervisor; it must meet the quality standards before it can be deemed acceptable. (5) After cleaning the pipelines and equipment of the oil system, reinstall them all at once to ensure a clean installation process and that no debris remains within the system. (6) Fill the fuel tank with ISO—VG46 anti-rust turbine oil for the first time, keeping the oil level at 80–90% of the gauge mark. (7) The main and auxiliary oil pump motors pass individual tests; the oil pumps and motors are aligned, and the couplings are installed. 1.7.1.2 Open-circuit oil circulation: The unit is equipped with a separate oil station. Before the unit is started, the oil system must be flushed with oil to verify that it meets the required standards, ensuring that the lubricating oil meets all specified performance requirements when reaching various lubrication points. (1) Reconfirmation: The process pipelines of the lubricating oil system (lubricating oil tank, high-level oil tank, oil cooler, oil filter, pipelines, etc.) are acid-washed and passivated, followed by rinsing with hot water. They are then dried with clean air and installed properly. If acid washing is carried out on-site, care must be taken to ensure that the waste acid liquid is discharged in compliance with environmental regulations. (2) Fill the fuel tank with flushing oil; the oil temperature and level must meet the requirements for starting the machine. The oil used for flushing should be GB11120-89 N46 anti-rust turbine oil, with a viscosity of 46 mm2/s at 40°C, an acid value of ≤0.02, a flash point (open cup) of ≥180°C, and a freezing point of ≤-10°C. The manufacturer must provide a detailed analysis report and a certificate of conformity for this oil. (3) Preparation steps: 1) Disconnect the oil supply pipes leading to each oil supply point of the engine from the connection flanges on the fuselage; disconnect the oil supply lines after the valves, as well as the flanges at the inlet end of the crankcase oil pump; then use temporary pipes to connect directly to the oil return pipes ； Stainless steel blind flanges are installed at the flanges where the lubrication pipeline branches connect to the main lubrication and control oil pipelines, as well as at the points where the turning gear oil pipes connect, in order to prevent lubricant from entering the bearings of the unit ； 2) Remove the oil filter element from the fuel station and install a temporary filtering screen for testing, with 120-mesh density ； Install metal filters with a mesh size of 80 to 120 on the unit return oil pipeline. The system carries out self-circulation within the fuel station, and the process is as follows: (4) Close the inlet and outlet valves of the cooling water for the oil cooler. Turn off the drain at each point. (5) Open the inlet and outlet valves of the oil pump, the lubricating oil pressure control valve, the pump outlet pressure control valve, and the shut-off valve leading to the high-level oil tank. (6) Check that all pressure switches, pressure gauges, pressure transmitters, and level gauge valves are closed; (when using oil, clean the pressure tapping pipes first before activating them one by one), and remove the flow control orifice plates between the oil filter and the cooler ； (7) First step in open-circuit oil transportation: Flush the interior of the oil station ； By manually turning the crank, check that the main and auxiliary oil pumps rotate smoothly, without any sticking or unevenness. Close the manual valves and branch lines before and after the lubricating oil control valve (PCV52110), as well as the main control valve for the lubricating oil. Open the manual valves and branch line valves before and after the oil pump outlet control valve (PCV52106). Start one of the oil pumps as required to flush the oil pump outlet pipe section, the oil pump outlet pressure control valve, the branch line valves, the oil cooler, and the air release lines of the oil filter. At the same time, switch between the oil cooler and the filter to ensure they are completely filled with oil, and alternately flush the air release lines (the drain valves of the oil cooler and filter are connected to the fuel tank using temporary lines; close these drain valves once the oil becomes clear again). Switch to the other oil pump every 4 hours to complete the individual testing of each oil pump as well as their alternating operation. Precautions: The oil pump should be filled before its first start-up. The oil cooler should be filled with oil first before cooling water is introduced. (8) Step 2 of open-circuit oil transportation: Flush the lubrication main pipe ； Close the manual valves and bypass valves before and after the oil pump outlet pressure regulating valve; continue to open the valves on the air release lines of the oil cooler and oil filter. Open the stop valves and bypass valves before and after the lubricating oil pressure regulating valve, close the main oil valve, and install stainless steel blind flanges at the connection points between the oil supply line and the main oil supply pipe on the high-level oil tank. Start the oil pump to flush the lubricating oil main pipe. (9) Step 3 of open-circuit oil transportation: Flush the high-level oil tank ； Close the shut-off valves before and after the oil pump outlet pressure regulating valve as well as the bypass valve, and the valves on the air release lines of the oil cooler and oil filter. Open the inlet and outlet valves as well as the bypass valve of the lubricating oil pressure regulating valve; close the main oil valve. Remove the stainless steel blind plate at the flange where the oil pipeline connects to the high-level oil tank and the main oil supply pipe. Install a 80–120-mesh filter on the return oil pipe of the high-level oil tank, and add a stainless steel blind plate at the flange at the end of the main lubricating oil pipe. Start the oil pump to flush the upper and lower oil pipelines of the high-level oil tank. (10) Step 4 of open-circuit oil transportation: Flush the control oil pipeline ； Close the shut-off valves and bypass valves before and after the oil pump outlet pressure regulator, as well as the valves on the air release lines of the oil cooler and oil filter; close the shut-off valves and bypass valves before and after the lubricating oil pressure regulator. Open the valve on the main oil pipeline. Start the oil pump to flush the control oil main pipe ； (11) During the open-circuit oil transportation process, check and adjust the oil pressure at each oil supply point to ensure it meets the requirements; observe the oil return situation in each oil return pipe through the oil return sight glass, and ensure that the amount of oil is sufficient. (12) Check that all connection seals in the lubricating oil system are leak-free; address any issues promptly. Depending on the specific circumstances, the following methods can be employed to improve the effectiveness of oil flushing: 1) Alternating hot and cold oil flow: To enhance the flushing effect and reduce the flushing time, the oil temperature can be varied between hot and cold levels. The relationship between temperature and time is shown in the diagram; one cycle lasts 8 hours, during which the low temperature is around 25°C. The temperature is around 75°C; when heating the oil, it is important to ensure that the oil temperature does not exceed 80°C to prevent the oil from deteriorating. As the oil temperature rises, all pipelines in contact with the oil should heat up; if some of these pipelines remain cold, the cause must be identified and resolved. 2) Variable-flow perturbation oil transportation: By appropriately opening and closing valves on the oil pipelines to create shock waves that flush the pipes, or by using high-flow flushing, both pumps can be started simultaneously. Additionally, nitrogen can be injected at the pump outlet to carry out air-gun oil transportation. 3) During the flushing process, use a wooden stick to tap the welded areas, elbows, and tees of the pipeline in the direction of oil flow, and regularly clean and remove the dirt accumulated in the dead corners and lowest points of the oil pipes ； 4) Alternating oil transportation on and off. (13) Every hour, remove the oil filter, the filter screen at the pump inlet, and the filter screens on the return oil pipeline for inspection and cleaning, and replace the filters with 80, 120, 180 (200) mesh sizes in sequence depending on the cleanliness of the oil. (Initially, adjust the inspection time accordingly based on the pressure difference.) (14) Switch the cooler and filter every 2 hours. (15) When there are no particulate, flaky, or fibrous impurities on the filter screen with a mesh size of 180–200, oil flushing is considered satisfactory; otherwise, the filter screen should be cleaned and flushed again after it has been reinstalled. 1.7.1.3 Closed-loop oil transportation cycle: (1) After the open-loop oil flushing is completed successfully, the flushing oil is drained from the lowest drain port of the tank and poured into waste oil containers; the tank as well as the overhead tank are then cleaned thoroughly ； Remove the temporary pipes and temporary filters, as well as the stainless steel blind flanges at the connections between the various lubrication line branches and the main lubrication and control oil pipelines; then restore the oil pipes and the regular filter elements to their original positions ； A filter with a filtration precision of ≥200 mesh is installed on the first pair of flanges at each oil supply point of the unit before oil enters. Install a 80-120 mesh filter on the return oil main pipe; remove the turbine thrust bearing and support bearing ； Remove the throttle orifice plate from the emergency shut-off valve; set the emergency shut-off throttle to the hook position and secure it. Take out the piston, spring, and spring seat from the quick-shut valve cylinder, keeping the end of the cylinder covered. Remove the throttle slide valve, spring, and spring seat as well. Temporarily install a 2–4 mm throttle orifice plate at the pressure oil inlet for the throttle valve, seal off the secondary oil inlet for the throttle valve, and reverse the orientation of the electro-hydraulic converter’s blocking plate. (2) Use an oil filter with a 108–200 mesh screen to add lubricating oil to the tank until the specified oil level is reached, in order to prepare for a full-circulation operation of the unit’s oil system; the process is as follows: (3) Start the main oil pump, and once it is operating properly, adjust the outlet valve so that the oil pressure reaches 1.1–1.5 Mpa. Continue the cycle for 12 hours to check the oil return at each fuel supply point; the oil volume should meet the requirements. The pressure difference before and after the oil filter must not exceed 0.15 Mpa; otherwise, the filter element should be cleaned and rinsed further until it meets the requirements. Note: Except for the first test run, when the manufacturer-provided sealing elements are used, at least 10 minutes before each subsequent lubricant circulation, the nitrogen gas for isolation behind the dry gas seal must be activated. Ensure that the pressure in front of the orifice plate used for isolating nitrogen is 0.6 MPa, while the pressure behind the orifice plate is around 0.02 MPa; this ensures that the pressure behind the orifice plate is slightly higher than atmospheric pressure, thereby preventing lubricant from entering the dry gas seal. (4) Check the pre-charged nitrogen pressure of the accumulator, then slowly open the isolation valve on the oil inlet line to integrate the accumulator into the oil system. (5) Check and clean all temporary filters every 2 hours until no hard debris remains on the oil inlet filter, and fewer than three soft impurities are visible per square centimeter; then stop the oil supply for flushing, clean the quick-close valve, throttle valve, bearings, as well as the removed parts, and remove the plating from the electro-hydraulic converter. Remove the zero-pressure orifice plates, blind plates, etc., and reinstall the orifice plates of the emergency shut-off valves, so as to restore the entire control oil system to its normal state. (6) Start the oil pump again; place the manual and remote control shutdown valves of the quick-shut components in their normal operating positions. Periodically switch between operating the control valves for the start-up oil and the quick-shut oil (either manually or electrically), in order to flush the pipelines carrying the start-up oil and quick-shut oil to the quick-shut valves ； Periodically place the test valve of the speed valve in the test position to flush the test oil pipeline. Continue until there are no hard debris on the oil inlet filter, and less than 3 soft impurities can be seen per square centimeter; then stop the oil flow and carry out flushing. (7) Remove the temporary filters at various points of the unit and restore the flange connections. Take samples of the lubricating oil for analysis; if it is not up to standard, drain all the oil from the tank as well as from the pipelines of the machine system, and then refill the tank with new oil that meets the specifications, bringing the oil level to the required level. During the oil circulation phase, in coordination with electrical and instrumentation systems, the oil level, oil temperature, oil pressure control, alarm, and interlock instruments of the oil system are tuned in accordance with design requirements, until they operate in a sensitive, accurate, and reliable manner.