Velox boiler


A Velox boiler is a high pressure, forced circulation, water-tube boiler. It was developed in 1930's by Brown Boveri Company 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 turbine which is connected to the compressor. It increases the flow of hot air to speed of sound. This increases the rate of heat transfer to the water coming from economizer into evaporating section causing it to generate more steam that goes in superheater via steam separator. Steam from superheater is at high temperature and pressure. This is used to operate turbines.

Components

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. 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:
Disadvantages:
Requires additional parts