Velox Boiler – its components and working
In this article we will see the design and working of Velox Boiler which is used steam power plant. First lets see the principle of its working.
Principle of Velox Boiler :-
Volex Boiler is based on the fact that when the vlocity of gas becomes more than the velocity of sound, the transmission of heat by gas becomes much higher as compared to heat transmission of heat at sub-sonic speed i.e lower than the speed of sound. In this boiler heat transfer rate or stream generation rate can be increased without increasing the size of the boiler. It can be increased by simply increasing speed of gas.
Construction :-
Volex Boiler contains many parts. Following are the parts of Velox Boiler in
working sequence :- i) Feed Pump ii) Economizer iii) Water Circulation Pump iv) Combustion Chamber v) Gas Turbine vi) Axial Compressor vii) Steam Seperator Viii) Super Heater . In this axial compressor is used to compress the air and pass it to the combustion chamber for better combustion rate.The economizer is used to preheat the water coming from feed pump.Steam Steam Seperator seperates the steam from water and functions of other parts will be explained in details in the working section.
Working :-
At first water is feed to the economizer from the feed pump. The economizer heats the water but does not heat up to the boiling point. Then the warm water from the economizer is passed to the water circulating pump. Then the water enters into the tube evaporating section which is inside the combustion chamber.
On the other hand , a gas turbine drives an axial air compressor . A gas turbine converts gas into mechanical energy and with that mechanical energy axial air compressor is driven. In axial air compressor the air flows through the axis of rotation of compressor.
The compressed air by air compressor enter into combustion chamber and passes from it. When this compressed air passes from the combustion chamber more heat is released by the fuel which increases the velocity of flue gas up to sound velocity .Flue gas is the gas exiting to the atmosphere via a flue by steam generator or furnance.
At first water is feed to the economizer from the feed pump. The economizer heats the water but does not heat up to the boiling point. Then the warm water from the economizer is passed to the water circulating pump. Then the water enters into the tube evaporating section which is inside the combustion chamber. The water passes through the evaporator 15 -20 times at high speed forced by water circulating pump.
On the other hand , a gas turbine drives an axial air compressor . A gas turbine converts gas into mechanical energy and with that mechanical energy axial air compressor is driven. In axial air compressor the air flows through the axis of rotation of compressor.
The compressed air by air compressor enter into combustion chamber and passes from it. When this compressed air passes from the combustion chamber more heat is released by the fuel which increases the velocity of flue gas up to sound velocity .Flue gas is the gas exiting to the atmosphere via a flue by steam generator or furnance. Flue gases pass from the fire tubes near the bottom of combustion chamber. Thsese fire tubes are surrounded by the evaporator water tubes.
When the water enters the evaporating tube at high speed , the heat form the gases are transferred at very high rate due to high speed of water and gas. After that mixture of water and steam is formed which is passed through water and steam separator. This separator separates the steam from water . The steam from steam seperator is passed to the super heater and after that passed for the pricess work. The remaining water again passes from the evaporator tube and this process continues until the water is converted to steam.
The flue gases from the fire tubes are send to the super heater for heating the steam . After that the flue gas from the super heater is send to the gas turbine where it rotates the gas turbine and after that gas passes through the economizer used to heat the water initially which are coming from feed pump.
Advantages of Velox Boiler :-
1) Velox Boiler is very compact and require very less space as compared to other boilers.
2 ) It can be started quickly and easily.
3) It has good flexibility.
4) It has hogh thermal efficiency about 90-95%.
5) It has high heat transfer rate.
