Steam at pressure
Pi expands through a nozzle and exits at very low pressure
(Px) and at very high velocity. The low pressure induces a
flow of load vapours at a pressure (P1) into the ejector. The
two streams i.e. the low pressure, high velocity steam from
the nozzle, together with the slower, entrained load vapours,
will mix as they converge into the throat of the ejector. Upon
leaving the throat, the gases slow down and regain pressure to
a pressure P2.
The load gases have been compressed from
their original pressure P1 to a new pressure, P2. We define
the compression ration for this ejector as P2/P1.
If
Ws kg/hr motive steam are required to entrain and compress Wl
kg / hr of load vapours, we define the entrainment ratio for
this ejector as Wl/Ws. These ratios are computer calculated
and are the key parameters in ejector design.
MULTI
STAGE EJECTOR SETS
In practice, for suction pressure
below 100 mbar absolute, more than one ejector will be used,
usually with condensors between the ejector stages. Condensing
of motive steam greatly improves Ejector Set efficiency. We
supply both barometric and shell-and-tube surface condensors
for this purpose.
APPLIED
VACUUM have been involved in designing, fabricating and
commissioning multi-stage Ejector Sets since the mid 1970's.
Our computerised designs yield steam and cooling water
efficiencies which are comparable to those offered by
manufacturers worldwide.
We have
supplied Multi - stage Ejector sets fabricated in Carbon
Steel, Stainless Steel, Titanium, PTFE, Carbon and
others.
The
Ejector Sets operate in a range of suction pressures down to
0,3 mbar absolute, and carry loads of up to 1000
kg/hr.
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