Simple Vertical Boiler’s definition, construction, working, applications, advantages and disadvantages have been discussed thoroughly in this article.
Definition of Simple Vertical Boiler
A simple vertical boiler is a type of boiler which generates steam at low pressure and in small quantities. It produces a pressure of almost 10 bar. Out of all the boilers, construction of this boiler is simple and straightforward.
This boiler holds extremely minimum space, so it is operated where slighter less land is used for working. The steam which is produced in this steam is utilized in low working conditions like small power plants for generating current. The cylindrical shell is generally placed in vertical position. It has got a capacity of generating 300 kg of steam/hr.
Construction of Simple Vertical Boiler
Cylindrical shell is the biggest and largest part of simple vertical boiler. The outermost part of this boiler is cylindrical shell while various other parts of boiler are inside this part. A firebox is located at the bottom inside the shell. The firebox includes a furnace, a grate and a ashpit. Grate is located at bottom of the firebox where coal or fuel is kept and burnt in furnace. Just below the grate, ashpit is located where the burning fuel is collected by burning fuel. With the help of fire hole, coal is introduced to the firebox. The cross tube is located at the centre of boiler and it is horizontally placed. Transmission of heat from flue gas to water is carried out due to the cross tube. There is a chimney which is placed above the cross tube. Flue gases from the cross tube is transferred to the chimney where it leaves the boiler and gets mixed in the atmosphere.
Components of Simple Vertical Boiler
- Cylindrical shell: It is the outlying cylindrical vertical shell of the boiler. All the other parts of the boiler are inside this shell. This cylindrical shell is almost filled with water and the remaining part of the shell is steam. Also, cross tubes are arranged in this shell.
- Cross tubes: One or more cross tubes are fixed or fastened to increase the heating surface and to improve and enhance the circulations of water.
- Grate: It is present at the bottommost part of the furnace. Generally, grate comprises of cast iron bars which are spaced to one side, so that the air which is required for combustion can pass through them. It is the place where coals are kept.
- Ashpit: It is located at the base of the boiler, below the grate. Purpose of ashpit is to collect ash deposited by furnace.
- Firebox: Burning of solid fuel takes place in firebox. It is used for the combustion of coal. Burning of coal takes place in firebox which is used to produce heat.
- Firehole: A fire hole is placed on one side of the grate. Coal is inserted in the furnace via this hole.
- Hand Holes: Hand holes are present at the opposite end of each cross tubes for cleaning purpose.
- Fusible plug: The purpose of fusible plug is to ignite the furnace of the boiler when the water level drop down below an unsafe level and consequently avoids the explosion, which is possible due to overheating of the tubes and the shell.
- Pressure gauge: They are used to calculate the pressure of steam inside the boiler. They are located in front of the boilers.
- Water level indicator: To indicate the water level inside the boiler, water level indicator are used. As the large area of the shell is filled with water, water level indicator is a very important device. Additionally, the firebox is surrounded by water. The quantity of water is considerable. While the remaining area of the shell consists of steam. The firebox is given with two cross-tubes. Due to this, heating surface and circulation of water increases.
- Chimney: A chimney is a vertical cylindrical pipe which expands from top of the firebox to the top of the shell. The main purpose of chimney is to pass the smoke from the boiler to the atmosphere.
Working of Simple Vertical Boiler
In the initial stage, fuel is added through the fire hole into furnace. Fuel is deposited on the grate which is situated at the bottom of the furnace. Burning of fuel is done which generates hot gases and the ash is collected in the ashpit produced by the burning of fuel. While through feed check valve, feeding of water is done in the boiler. With the help of water level indicator, level of water is adjusted. The hot gases which are produced by the burning of fuel are moving upwards.
The upward moving gases encounters the inclined cross tubes and then the waste gases are transmitted in the atmosphere through the chimney. Meanwhile, the heat is transmitted from flue gases in the cross tubes to the water and then the steam is produced by heating the water. Since the tubes are inclined, the flow of water in the boiler is by natural circulation. Also, water in the boiler is converted into steam due to heat transfer. Further, this steam is then collected at the steam space of the boiler and then taken out through steam stop valve to engine or gas turbine or any other use. Simple vertical boiler is extremely close-packed or compact and they can be easily transported. The efficiency of this boiler is comparatively low. To be more precise, it is 50% approximately.
Application of Simple Vertical Boiler
Following are the applications of the Simple Vertical Boiler:
- Simple vertical boilers are involved in road vehicles viz. steam wagons or steam lorry.
- A prominent application is used by simple vertical boiler which is steam tractor.
- These boilers are mainly used for the applications in railway locomotives e.g. a railway steam engine.
- In specific parts of world, simple vertical boilers are used in steam donkeys.
- These type of boilers are used in steam steels and steam cranes.
Advantages of Simple Vertical Boilers
Below mentioned are the advantages of the Simple Vertical Boiler:
- Since it has vertical cylindrical shell, it occupies very less space on the ground.
- As there are less number of parts, the inceptive cost is low.
- It can be easily installed and operated.
- The replacement of parts are easily available.
- The cost of maintenance is low.
- It has water level intolerance.
Disadvantages of Simple Vertical Boilers
The disadvantages of the Simple Vertical Boiler are:
- The steam production is low because of the small-sized grate.
- The impurities simmer down at the bottom and stops the water from heating up.
- As design of the simple vertical boiler is vertical, it restricts the work in many places.
- As boiler tubes are short, very little time is for flue gas to heat the tube and therefore less steam is generated.
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