Three-level-roots-water ring intelligent frequency converting control vacuum system and control method thereof

Abstract

The invention discloses a three-level-roots-water ring intelligent frequency converting control vacuum system. The system comprises a first-level high-pressure-difference roots mechanical vacuum pump, a second-level high-pressure-difference roots mechanical vacuum pump and a traction liquid ring pump; the first-level roots mechanical vacuum pump and the second-level roots mechanical vacuum pump are each provided with a frequency converting motor, a frequency changer and an air exhaust opening condenser; the inlet end of the first-level roots mechanical vacuum pump and the inlet end of the second-level roots mechanical vacuum pump are provided with pressure transmitters, and the pressure transmitters and the frequency changers are all connected with a control cabinet; through the pressure feedback value given out by each level of pressure transmitter, the frequency changers are used for carrying out speed adjustment on the rotating speed of the roots mechanical vacuum pumps, and the pressure difference value is adjusted through a bypass pipeline; and the frequency changers are used for adjusting the rotating speed of the roots mechanical vacuum pumps, the pressure difference value is adjusted through the bypass pipeline, and the pressure difference balance and safe running of the first-level roots mechanical vacuum pump and the second-level roots mechanical vacuum pump are achieved.

Description

technical field [0001] The invention relates to a three-stage Roots-water ring intelligent frequency conversion control vacuum system of a thermal power plant condenser vacuum pumping energy-saving system. Background technique [0002] In thermal power plants, the vacuum of the condenser has a great influence on the coal consumption of power generation. Taking a 300-330MW unit as an example, every time the vacuum increases by 1Kpa, the corresponding power generation coal consumption decreases by 2.6g / kWh. At present, the commonly used vacuuming equipment in power plants is water jet pump and water ring pump, and the former is gradually replaced by the latter. The performance of the water ring vacuum pump is related to the state of the pumped gas (pressure, temperature) and the temperature of the working fluid. At the same time, affected by the "limit suction pressure" during operation, local water hammer is prone to occur on the surface of the impeller. The operation noise...

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Problems solved by technology

However, because the principle of the Roots air-cooled pump is that the gas is cooled and then compressed, the actual operating efficiency of the pump is relatively low (the part of the compressed discharged gas needs to be returned to the pump cavity to mix with the inhaled gas, resulting in a large At the same time, due to the large pressure difference and sealing, the actual operating efficiency of the three-lobe Roots vacuum pump is not more than 40%, while the efficiency of ordinary Roots vacuum pumps can generally reach 50%. We provide Roots vacuum pumps can reach up to 53% efficiency), energy consumption is relatively high, and the floor area is large

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