The maximum compression ratio for a steam jet vacuum pump depends on the suction pressure and the pressure of the available motive steam. Multi-stage steam jet vacuum pumps can be designed for suction pressures down to 1 mbar or lower.
STEAM EJECTOR SERIES
If the condensation temperature is too low at the intermediate temperature, several ejectors might be installed in series without condensers in between. Between two jet pumps the motive steam is condensed as far as possible in order to reduce the energy requirement of the next stage. Therefore, for low suction pressures, jet vacuum pumps shall be combined in series. Single stage steam jet vacuum pumps feature a compression ratio between 1:7 and 1:10. The convergent section of the diffuser reduces the speed, pressure shock occurs in the throat of the diffuser and divergent diffuser section increases the cross-sectional area to the flow and speed are turning into pressure energy. The speed is then transformed into pressure. Motive steam at high speed is mixed with the suction flow and enters the convergent-divergent diffuser. This creates a depression that enters the suction load into the ejector. The motive steam expands up to a pressure below the suction pressure. The result is a supersonic speed out of the nozzle. This occurs by an adiabatic expansion of motive steam through a convergent-divergent nozzle from the motive pressure to suction pressure. The operating principle of an ejector is to convert pressure into speed. Steam jet ejectors are considered an alternative to mechanical vacuum pumps because no source of power is required other than the motive gas, they have no moving parts, they are reliable, easy to install, to operate and to maintain.
They are especially effective in the chemical industry where an on-site supply of the high-pressure motive gas is available. Steam jet ejectors offer a simple, reliable, low-cost way to produce vacuum. They are a reliable alternative to vacuum pumps.
Multi-stage steam jet vacuum pumps are used in various industries to remove gas molecules from a volume in order to leave behind a partial vacuum.
0 kommentar(er)
