Operating Characteristics of Steam Jet Pump Extraction System

Steam jet pump is the use of high-pressure steam after the nozzle acceleration, get supersonic airflow, into the mixing chamber, causing low pressure in the mixing chamber, will be pumping gas (or steam) inhalation, and with the momentum and energy exchange, into the diffuser ; In the diffuser contraction section, the pressure of the mixed gas increases, the speed drops to reach the throat of the diffuser, the velocity of the mixed gas stream drops to the vicinity of the sound velocity, and in the diffuser expansion section, the speed is further reduced to the exit speed Close to zero, at this time, the pressure of the mixed gas is higher than the outlet pressure of the pump to be excluded, so as to achieve the purpose of pumping. Working steam through the nozzle expansion, if the pressure at its outlet is much higher than the pressure of the gas being pumped, the working steam due to over-expansion of the jet dispersion, this time without pumping effect; if the pressure at the outlet than the ratio Pumping gas pressure is much lower, then the working steam is compressed, forming a cylindrical jet in the nozzle and can not block the flow channel, resulting in exhaust chamber and suction chamber "short circuit" at this time also does not have the role of suction. Multistage jet pump in all pump has its own pumping curve, each stage of the pump work along their respective suction pressure, exhaust pressure and pumping capacity of the characteristic curve changes, in order to ensure the stability of pumps at all levels, the requirements During the working process of the system, the parameters of the steam system and the condensate system of the pump should be kept as constant as possible. When the status parameters of the working medium fluctuate within the allowable range, the suction pressure and discharge pressure of the pumps at all levels will be within the appropriate range Internal changes, will not affect the normal operation of the jet pump system, but the work of the state parameters of the general changes caused by jet pump instability. In order to ensure the stable operation of multi-stage pump system, all the pumps in the system should be well matched, so that each level of pump is at its own working point, so as to prevent one of the pumps from operating under overload condition. When the gas load increases, the jet pump suction pressure will rise significantly (about 1.6 times), while the exhaust pressure rises slowly (about 2%); if the gas load decreases, the jet pump suction pressure drops, the outlet pressure decline. When the pump suction pressure is constant, if the working steam pressure increases, the exhaust pressure increases, the amount of exhaust increases. The cooling water temperature will generally vary with the seasons, the pump design is generally based on the summer water temperature. If the water temperature is low, the performance of the pump at all levels before the condenser will not be affected. The pump behind the condenser will reduce the gas load of the next pump due to the low condensing effect of the water temperature, becoming steady. However, in order to make the discharge pressure of the last stage pump> 10-5 Pa, it may be uneconomical to increase the working steam consumption of the last stage of the pump, which may cause the pump system to fail to work stably when the working steam is constant.

Fixtec Polishers

Fixtec Power Tools Co., Ltd. , http://www.fixtec-tools.com

Posted on