Important knowledge about feed water degassing systems


The physical process of thermal degassing is used to separate dissolved gases from water. The water to be degassed is heated to its boiling temperature with the aid of supplied heat, so that dissolved gases escape from the water by diffusion at the phase interfaces or in the form of bubbles.

Feed water degassing systems for thermal degassing are usually built with a trickle degasser. The trickle cup internals inside the degasifier increase the surface area of the water flowing through the degasifier, which promotes heat and mass transfer.

In thermal degassing, make-up water, condensate and heat continuously flow in, while boiler feed water and residual steam, known as vapours, flow out.

Description of the procedure


Thermal degassing is based on the dependence of gas solubility in water on concentration and partial pressure equilibrium (Henry's law), temperature and boiling state. The solubility of gases in water decreases with increasing water temperature - in the boiling state the solubility shows towards zero.

The mass transfer required for degassing takes place through diffusion at the phase interfaces and through the escape of gas and vapour bubbles. Since the separation of all gases is necessary for the boiler feed water treatment, the liquid to be degassed must be boiled as completely as possible - this is done taking into account the influence of hydrostatic pressure on the boiling point and the surface tension at the phase interfaces.

EUGEN BÜDENBENDER Behälter- und Apparatebau usually manufactures this principle using a trickle degasser with internal trickle cup internals. The feed water tank contains a device for heat supply in the form of heating steam. Thus steam flows from bottom to top in cross countercurrent to the water to be degassed through the vessel into the degasser. Condensate and make-up water flow from top to bottom through the deaerator into the vessel, whereby the trickle on the trickle cup internals increases the surface area of the inflowing water and condensate and promotes heat and mass transfer.

In the deaerator, the steam introduced condenses to a large extent on the incoming water and heats it up to its boiling temperature. Residual steam emerges as vapours at the upper end of the deaerator and carries off the gases separated from the water.

Feed water tanks with deaerator from EUGEN BÜDENBENDER Behälter- und Apparatebau can be operated over a wide load range and designed for high heating ranges. Depending on the design of the heating system, up to 95% of the total volume of the feed water tank can be used as storage volume. Heat is usually supplied by heating steam. Furthermore, alternative heating concepts, e.g. for heat recovery, are technically possible.

Individual solutions - Made in Germany


In 1948, company founder Eugen Büdenbender laid the foundation for our business today in the Siegerland, the region of Germany most famous for the iron-processing industry. Under the simplest conditions, but with a high level of expertise, the first tanks were manufactured in the so-called “Alte Halle” (old hall). With the necessary skill, diligence and thrift, Eugen Büdenbender was able to establish the young company.

Over the years, the company has successfully worked towards being one of the most renowned businesses in the field of tank construction and mechanical engineering. Numerous orders and the trust our customers put into our work every day speak for this.

To us, tank construction is not only another source of income, but is the passion of every one of our employees, who – together with the management – strives to make our company’s visions a reality.

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Thank you for your interest in feed water degassing systems from EUGEN BÜDENBENDER Behälter- und Apparatebau. We would be pleased to inform and advise you in advance about the most suitable application for you. Please do not hesitate to contact us.

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