All Venturi Equipment Ltd
All Venturi Equipment Ltd

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Desuperheaters

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Desuperheaters & Desuperheating

Steam Desuperheater are designed to reduce the temperature of super heated steam to produce lower operating temperatures. The majority of installations fall into these typical installations.

In operation the majority of our Desuperheaters require the water pressure to be equal to the main line steam pressure with the exception of the Type 6910 and Type 6905 where the water pressure must be at a greater pressure to the main line steam. Water is syphoned in to the combining tube assembly, where it is heated and then mixed with a small proportion of steam passing through the throat region. This is then introduced in to the steam line as a finely atomized mist which alleviates the requirements of thermal liners and impingement shields.

Desuperheater selection is usually defined by the operating characteristics and required duty. Our specific Desuperheater types can be seen below:

Mechanical Dump Desuperheater Type 6905 Mechanical Dump Desuperheater

The Type 6905 Mechanical Atomising Dump Desuperheater is designed to be an emergency desuperheater, which protects main turbine condensers or similar types of equipment when steam dumps occur. The operating principle is that high-pressure water liquid is sent through radially located nozzles on a pipe carrying the gas to be cooled. The water is atomised and evaporated in the gas stream thus cooling the steam in amounts equal to the enthalpy change plus the vaporisation value of the cooling medium.


Surface Absorption Desuperheater Type 6910 Surface Absorption Desuperheater

The Type 6910 Surface Absorption Desuperheater is a unique unit in a compact design that allows for infinite turndown (large flow rate variation) and saturated characteristics on the discharge. The operating principle is that water is injected into the desuperheater onto a baffle plate that distributes water across the reaction rings. The reaction rings provide a large surface area over which the hot vapour is forced to pass. The hot gas is then cooled by absorption of the water when contacting the reaction rings. The saturated vapour flows out of the desuperheater outlet and excess water drains through the bottom and is removed through a trap. The reaction rings in the Type 6910 unit extend the cooling water surface, a feature not available in other unit types.


Venturi Desuperheater Type 6940 & 6950 Venturi Desuperheater

Type 6940 and 6950 are Venturi Desuperheaters. Water entering the desuperheater is preheated in the circulatory chamber around the water diffuser tube and is introduced in many small jets to assist final atomisation by the steam flow through the centre of the throat. When leaving the throat, the mixture of steam and water enters the venturi section for turbulent mixing prior to entering the main steam line in a fog-like condition without contacting the sidewalls. This provides maximum desuperheating effectiveness and a minimum of wear in the discharge piping. The Type 6940M Desuperheater is a miniature version of the Type 6940. It was developed to handle small quantity steam applications found in heating, air conditioning and process industries.


Attemperator Desuperheater Type 6952 & 6953 Attemperator Desuperheater

The Type 6952 and 6953 are Attemperator Desuperheaters. Water entering the desuperheater is preheated in the circulatory chamber around the water diffuser tube and is introduced in many small jets to assist final atomisation by the steam flow through the centre of the throat. When leaving the throat, the mixture of steam and water enters the venturi section for turbulent mixing prior to entering the main steam line in a fog-like condition without contacting the sidewalls which provides maximum desuperheating effectiveness and a minimum of water in the discharge piping.


Atomising Desuperheater Type 6970 Atomising Desuperheater

The Type 6970 are ejector-type steam Atomising Desuperheaters which require a relatively small amount of high pressure steam, which draws the cooling liquid into the atomising head, so producing a fog which is discharged into the main steam line. Due to the fine atomisation of the liquid this allows intimate mixing and cooling of the steam. This type of unit can generally offer a higher turndown and is not subject to the same velocity constraints as with the venturi type units, therefore this type of unit will be more economical especially when larger pipe sizes are required. Turndown in excess of 50:1 can be achieved in many conditions.


Desuperheater Control System (Typical Layout for Type 6970)

Type 6970 Typical Control Schematic - Click to enlarge
(Click to enlarge, opens new window)

A desuperheater is not a single piece of equipment that succeeds or fails on its own, but is only one of several distinct system components. For a successful application, system engineering is a must. Neglect of any one component may result in system failure, no matter how excellent the design and engineering application of the other components. Therefore, all of the control components must be carefully selected for the specific application to be handled.

System Valves and Controls

Important Note: A control system cannot successfully hold a temperature that is no higher above saturation than the controller's degree of sensitivity and deadband.

Registered Address - All Venturi Equipment Ltd, Venturi House, Edensor Road, Longton, Stoke on Trent, Staffordshire, ST3 2QE, United Kingdom
Tel. : +44 (0) 1782 599800, Fax. : +44 (0) 1782 599009
Company Registration Number - GB 2034506