3 operation – Bronkhorst CEM W-300B User Manual
Page 12
BRONKHORST HIGH-TECH B.V.
3 Operation
3.1 General
The Bronkhorst HIGH-TECH B.V. CEM system is designed in such a way that it will meet user process
requirements. In order to achieve good results, it should be operated according to the guidelines stated in the
following paragraphs.
3.2 Power and warm-up
Before switching on power, check if you have connected all devices according to the system description
and/or hook-up diagram. Check the liquid and gas connections, and make sure there are no leakages, turn
on power for at least 30 minutes to warm up flow controllers. For start up of the liquid controller consult the
appropriate manual. During this warming-up period the temperature of the heat exchanger might be brought
up to its operating point.
3.3 Start-up/close-down
Be sure that the temperature of the heat exchanger is in accordance with the process conditions to be
adjusted, and furthermore should all pressure levels have the correct values.
After this has been assured, first start bringing up the carrier gas flow to the correct level. Once this flow has
been stabilised, the liquid flow can be applied to the system, by gradually increasing the setpoint of the liquid
controller. Now your CEM system should be operating.
When closing down operation of the system proceed in reverse order.
First stop the liquid flow, and after that the gas flow.
Note:
Make sure there is always gas flow whenever liquid flow is present.
Operation example:
Application: Generation of humid gas
The CEM system can be used for generating certain humidity in a gas stream. The F-201 gas flow controller
controls the gas flow and the LIQUI-FLOW® controller controls the humidity, the water.
The water is mixed with the gas and consequently evaporated. The humidity at a certain temperature
corresponds with a certain ratio of gas and water, this ratio can be set by the flow controllers.
Example:
At atmospheric pressure, at 80°C, 2 ln/min Air has to be moistened. Which water flow is needed for a r.h. of
50%. The vapor pressure of water at 80°C is 473.3 mbar according to Fluidat.
At 100% r.h., the (mole) ratio between gas and water is
MoleRatio:
877
.
0
)
3
.
473
25
.
1013
(
3
.
473
=
−
=
X
So in a gas flow of 2 ln/min, the saturated water flow (100% r.h.) is:
754
.
1
2
877
.
0
=
⋅
=
Φ
⋅
=
Φ
gas
water
X
[ln/min]
and in [g/h]
56
.
84
]
[
4
.
22
]
[
60
]
[
18
]
[
754
.
1
ln
min
min
ln
=
⋅
⋅
mol
h
mol
g
[g/h]
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