Energy saving system of electrically driven feed pump of power frequency-variable frequency switching type liquid coupling

Abstract

The invention relates to an energy saving system of an electrically driven feed pump of a power frequency-variable frequency switching type liquid coupling, and belongs to the technical field of energy saving transformation of electrically driven feed pump sets driven by a liquid coupling in a power station. the energy saving system is characterized in that a frequency converter and a power-frequency bypass is arranged between a power supply frequency converter and a motor on the condition that the connection type of original electrically driven feed pump sets are cont changed. According to the energy saving system, the frequency converter and the power-frequency bypass are mounted between the power supply breaker and the motor, the power frequency-variable frequency power supply is input in the motor by switching, a front-mounted pump is coaxially driven by one end of the motor, a liquid coupling input shaft is coaxially driven by the other end of the motor, a feed pump is driven by a liquid coupling output shaft, and a lubrication pump and a working oil pump are designed and mounted in a liquid coupling lubricating oil system and a working oil system, so that the same liquid coupling has two operation manners; for meeting requirements of the power frequency-variable frequency operation manners of the feed pump sets, the front-mounted pump is changed into a front-mounted pump which can operate in both a constant speed manner and a variable speed manner. The energy saving system of the electrically driven feed pump of the power frequency-variable frequency switching type liquid coupling is simple in structure and rational in design, and has two operation manners including a volume-velocity-regulated speed-regulation type liquid coupling in a power-frequency constant speed input process and a pump-pulley-regulated speed-increase gear box in a variable frequency speed-regulation input process.

Description

technical field [0001] The invention belongs to the technical field of energy-saving transformation of an electric feedwater pump set driven by a hydraulic coupling in a power plant. Background technique [0002] Most of the electric feed water pumps for coal-fired power units in service are driven and adjusted by speed-regulating hydraulic couplings. Speed ​​regulation. The efficiency of a variable speed fluid coupling is always equal to the ratio of the turbine speed to the pump wheel speed. The best operating point of the speed-regulating hydraulic coupling is its rated operating point, which has the highest output power, the highest output speed, and the highest efficiency. The speed-regulating fluid coupling has the highest operating efficiency only under rated conditions. The more the deviation from the rated working conditions, the lower the efficiency, that is, the lower the speed ratio, the lower the efficiency. This is the biggest drawback and shortcoming of th...

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Problems solved by technology

In this way, even if the unit is running at rated load, the operating speed of the hydraulic coupling is already 10% to 15% lower than the maximum speed value. During the operation of the coal-fired power unit in service, due to the load requirements of the power grid, the coal-fired power unit must participate in peak regulation. , the load rate is often operated between 65% and 75%, and the opening of the spoon tube of the speed-regulating hydraulic coupling is often 60% to 65%. The abnormal rise of the working oil temperature is obviously uneconomical. Under this operation mode, the power saving space is generally more than 20%.

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