EWT Water Technology – Water Treatment

EWT Water Technology

Vacuum Deaeration

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The following descriptions refer to thermal vacuum deaeration of water only, meaning deaeration at less than atmospheric pressure with continuous inflow of heat. Intermittent deaeration processes without heat inflow are not covered, while →thermal deaeration processes at higher than atmospheric pressure are described elsewhere.

Thermal deaeration is a physical process for removal of dissolved gases from water. For thermal deaeration, the water to be deaerated is brought to the boiling point by addition of heat. For vacuum deaeration, the boiling occurs at less than atmospheric pressure, resulting in a boiling temperature of less than 100 °C. This is of advantage especially for hot water or warm water systems, e.g. in district heating.

A vacuum deaerator may be designed either as a separate upright vessel, or attached to a downstream storage tank. The required heat inflow is usually achieved with either steam or hot water, either by direct contact heating and mixing or indirectly by heat transfer through a tube bundle. The vacuum is usually created by either jet pumps or liquid ring vacuum pumps, supported by condensation processes within a vent condenser.

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Design Example:

vacuum deaerator

Vacuum deaeration plant: Vacuum deaerator, upright, without storage vessel, including vent condenser, liquid ring vacuum pumps, valves, and instrumentation.

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Common Applications:

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Technical Data:

deaerated water mass flow available from approx. 5 000 up to 300 000 kg/h ≈ 1.5 ... 80 kg/s for each line
amount of lines usually 1x100 %
deaerated water quality oxygen < 20 μg/L O2 (standard)
< 50 μg/L O2 (option)
free carbon dioxide < 1 mg/L CO2
operating pressure, absolute < 1 bar, usually approx. 0.1 ... 0.6 bar
operating temperature < 100 °C, usually approx. 45 ... 85 °C
storage time water seal without separate storage vessel approx. 5 ... 15 minutes
with additional downstream storage vessel usually approx. 60 ... 120 minutes
material options deaerator • stainless steel (e.g. 1.4541, 1.4571)
storage vessel • carbon steel (e.g. S235JR, P265GH)
• stainless steel (e.g. 1.4541, 1.4571)
pipelines • polyvinyl chloride (PVC-C)
• polypropylene (PP)
• carbon steel (e.g. P235GH)
• stainless steel (e.g. 1.4541, 1.4571)
valves • polyvinyl chloride (PVC-C)
• polypropylene (PP)
• grey cast iron (e.g. 5.1301)
• spheroidal cast iron (e.g. 5.3101, 5.3106)
• cast steel (e.g. 1.0619)
• stainless steel (e.g. 1.4408)
gaskets • EPDM
• NBR composite
• graphite composite
control options closed loop pressure control • electric, intermittent (on/off)
• electric, continuous (PI, PID)
closed loop temperature control • mechanical, continuous (P control)
• electric, continuous (PI, PID, or 3-point control)
closed loop level control • mechanical, continuous (P control)
• electric, intermittent (open/closed)
• electric, continuous (PI, PID, or 3-point control)

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2018-05-05 • water treatment made in GermanyCompany InformationPrivacy