Abstract : Fushun Petroleum Plant No. 3 is a petrochemical enterprise. Previously, due to technical limitations, the pumps in its production units operated at a constant speed. Flow rate, pressure, and liquid level were controlled by regulating valves, resulting in significant energy loss due to valve resistance. Starting in 1990, we applied frequency converters to over 100 motors in the plant, achieving significant energy savings, with an average saving rate exceeding 50%. Power consumption in each production unit decreased markedly. This also resolved a series of related equipment safety issues. In recent years, technological advancements have led to a decrease in equipment prices, creating favorable conditions for wider application. In 1997, we successfully applied high-voltage frequency conversion technology to pumps for the first time, achieving excellent results. Keywords : High-voltage frequency conversion technology, petrochemical application 1. The Necessity of Applying High-Voltage Frequency Converters to Molecular Sieve P501 Pumps The molecular sieve unit at Fushun Petroleum Plant No. 3 has an annual production capacity of 140,000 tons. It is a modern unit built entirely using American UoP technology and plays a crucial role in the process technology of Fushun Petrochemical Company. The most important component of the molecular sieve unit is the 500 unit—the hot oil system, and the P501 pump is the key to this system. Its simplified process flow is shown in Figure 1: The inlet tank V501 of the molecular sieve P501 pump is a high-level nitrogen-sealed tank with an instrumented liquid level detection device; the nitrogen pressure is 0.5 MPa. There are three P501 hot oil pumps: inlet pressure 0.5 MPa, rated outlet pressure 1.94 MPa, minimum continuous flow rate 366 m³/h, rated flow rate 1100 m³/h, hot oil temperature 300℃ (-0℃ to +28℃), and speed 2970 r/min. There are three P501 motors: rated voltage 6000V, rated operating current 58.7A, motor capacity 610kW, F-class insulation, and rated speed 2980 r/min. There is a flow orifice plate on the pump outlet main line. After exiting the pump, the hot oil flows through the coils inside the H501 heating furnace for heating. Depending on the processing capacity of the unit, the furnace requires a different and stable flow rate of hot oil. The auxiliary line: Hot oil exiting the heater enters 11 reboilers. Each reboiler has a pressure control valve, and the amount of hot oil entering each reboiler is controlled by the DCS. Excess hot oil returns to the pump inlet tank V501 through the auxiliary line pressure control valve 5FRC10. The hot oil exiting the 11 reboilers, after heat exchange, also flows to the pump inlet tank. [b][align=center]For more details, please click: Application of High-Voltage Frequency Converters in Molecular Sieve Machine Pumps[/align][/b]