Blowdown – Purging, Venting, Exhausting Tanks and Vessels from High Pressure to Vacuum
Venturi Jet Ejectors (also called Eductors or Venturi Jet Pumps) with MAWP up to 10,000 psig for creating vacuum in vessels, tanks and pipelines
Taking internal pressure from 50 – 5000 psig down to Vacuum
Fox Venturi Gas Eductors or Ejectors have been used in high pressure blowdown applications for 30+ years. In this application, a tank or vessel can begin the blowdown or exhaust process by simply blowing out through a venturi ejector – to atmosphere or scrubber or flare.
During this first step, the venturi eductor is just a dumb elbow. As the tank or vessel empties out (blows down) through the through the venturi jet pump – the motive flow to ejector is off. It is not operational.
When tank pressure approaches 0 psig, a pressure sensor trips the on/off valve on the MOTIVE gas supply – and the gas ejector begins to function as a vacuum pump. The venturi eductor, now operational, can then complete the blowdown cycle. If motive gas (air, N2, nat gas, other) is available at 90 – 150 psig a final internal pressure of about 2 psia can be obtained.
This process requires that the venturi jet ejector be designed to handle the initial gas pressure. Fox machined from bar, all-welded ejectors have no problem with an MAWP of 5000 to 10,000 psig or higher, with any end connections required.