First, in the design of the refrigeration system, the refrigeration system is designed with the hottest weather and the largest load, and the remaining amount is calculated. However, in reality most of the time will not be operated under full load, so the potential for energy saving is greater.
Second, because the freezing (coal) pump adopts Y-â–³ start-up mode, the starting current of the motor is 4-7 times of its rated current, and the starting current of a 90kw motor can reach 300-500A, in such a large current impact. The service life of the lower motor is greatly reduced. At the same time, the mechanical shock at startup and the water-sagging phenomenon at the time of stopping the pump will cause damage to the bearings, valves, pipes, etc., thereby increasing maintenance workload and spare parts conditions.
In summary, in order to save energy and cost, it is necessary to reform the freezing (medium) pump.
Third, the transformation program has two kinds:
1, simple transformation
The frequency converter is directly connected with the freezing (medium) pump, and can be frequency-variable and set the lower limit of 25HZ and the upper limit of 45HZ. The customer can freely adjust according to different temperatures.
2. Closed-loop control
The scheme ensures the minimum operating frequency of a cryopump under the condition of ensuring the supply of the chilled water at the end of the equipment, and sets it as the lower limit frequency and locks it. The frequency adjustment of the frequency conversion frozen water pump is the temperature sensor detection on the returning water of the chilled water system. Chilled water return temperature, and then through the temperature controller to control the inverter frequency increase or decrease. The control mode is: when the temperature of the frozen return water is greater than the set temperature, the frequency of the inverter is increased steplessly (when less than the time, the frequency converter drops automatically, thus achieving automatic control and energy saving)
3 For 93KW refrigerated (medium) pumps, the general energy-saving rate is over 15%. According to different users, reasonable use of energy-saving rate is higher.