The drain system of LP heater was designed as a combined operation system of step-by-step gravity drain and drain pump. When the said pump is operating at constand speed

troublesome problems

shch as higher fault rate

larger pipeline vibration

shorter time for putting LP heater into operation etc

are ubiquitous. Using frequency-converting technology

the water level in LP heater can be controlled by converting the frequency of drain pump’s power supply instead of adjustment with valves. More than one year’s operation of the retrofitted system proved that the operation of said drain pump to be stable

safe and reliable .The rate of putting LP heater into operation reaches 100% and the effect of energy-saving is obvious. The said technology has been rapidly spread in use.