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A Velox boiler is a high pressure, forced circulation,
water-tube boiler A high pressure watertube boiler (also spelled water-tube and water tube) is a type of boiler in which water circulates in tubes heated externally by the fire. Fuel is burned inside the furnace, creating hot gas which boils water in the steam-gen ...
. It was developed in 1930s by
Brown Boveri Company Brown, Boveri & Cie. (Brown, Boveri & Company; BBC) was a Swiss group of electrical engineering companies. It was founded in Zürich, in 1891 by Charles Eugene Lancelot Brown and Walter Boveri who worked at the Maschinenfabrik Oerlikon. In 19 ...
of Switzerland. The first public demonstration of Velox was at VDI Scientific Conference in Berlin on 15 October 1932.


Design


Velox principle

From Brown Boveri Review


Working

Velox boiler is based on the principle that heat transfer rate increases when velocity of flue gas is more than speed of sound. This increases steam generation rate. Flue gases are used to turn a turbine which is connected to the compressor. It increases the flow of hot air to or above the speed of sound. This increases the rate of heat transfer to the water coming from the economizer into the boiler tubes causing more steam to generate which then goes into a superheater via a steam separator. Steam from superheater is at high temperature and pressure. This is used to operate turbines.


Components

* Water feed pump * Economizer for water preheating * Hot water circulating pump * Tube evaporating section * Turbine * Compressor * Steam separator * Superheater


Uses

Velox boiler was primarily marketed for electricity generation. They were anticipated to be used in steam locomotives on land as well as on sea but eventually lost to efficiency and cost effectiveness of supercharged diesel engine and constant pressure combustion
gas turbine A gas turbine, also called a combustion turbine, is a type of continuous flow internal combustion engine. The main parts common to all gas turbine engines form the power-producing part (known as the gas generator or core) and are, in the directi ...
. Advantages of somewhat reduced weight and purely rotary motion were greatly offset by the fact that Velox boilers were little over half efficient compared to diesel engines. ''Advantages:'' * Compact design. * Flexibility of design. * High combustion rate. * It can be quickly started. ''Disadvantages:'' Requires additional partsVelox Boiler Locomotives
/ref> * Electric starter. * Gas turbine to drive air compressor. * Steam turbine for water circulation.


References

{{reflist Steam boiler types