Abstract : Based on the actual situation of the factory, in order to reduce power generation costs, the boiler feed pump was modified using a frequency converter combined with a pressure transformer and intelligent instruments to achieve energy saving and consumption reduction.
Keywords : Cyclic; Frequency conversion; Inverter; High-power switching elements
1. Introduction
In the original operation and adjustment of the feedwater system of old boilers, the feedwater pump flow rate was controlled by inlet and outlet valves and the return header to ensure constant pressure water supply during normal boiler operation. This water supply method has many drawbacks. First, control by pump inlet and outlet valves changes the water flow rate by altering the water resistance in the pipeline while keeping the pump speed constant. Second, the use of the return header causes water to repeatedly circulate within the pump body. During these two adjustment processes, the motor and pump always operate at rated speed, resulting in significant active power loss and increased power generation costs. In addition, relying on workers to observe the header pressure gauge or operate the valve opening according to dispatch orders is somewhat time-consuming, sometimes causing fluctuations in the water supply system, and is not well-suited for responding to abnormal accidents. In view of the above problems, we proposed that the pressure transmitter on the water supply main pipe be used to detect the water pressure in the main pipe. The DC1~5V signal of the pressure transmitter is sent to the SWP-TS815 dual-beam intelligent instrument, which is compared with the upper and lower pressure limits set in the intelligent instrument. The output DC4 20mA signal is then used to control the frequency converter to adjust the speed of the motor and pump, and implement closed-loop control to ensure constant pressure water supply from the water supply main pipe (when the return main pipe is not working and the inlet and outlet valves are fully open).
For details, please click: Application Effects of Variable Frequency Speed Control Technology Combined with Pressure Transmitters and SWP Smart Instruments in Boiler Feedwater
