Cochran Boiler – Parts , Diagram , Construction and Working
What is Cochran Boiler?
Cochran Boiler is a vertical drum axis, natural circulation, natural draft, low pressure, multi-tubular, solid fuel fired, fire tube boiler with internally fired furnace. It is the modified form of simple vertical boiler. In this boiler, the fire tubes are placed horizontally. The efficiency of this boiler is much better than the simple vertical boiler.
Main Parts and Construction
1. Shell: It has a vertical axis cylindrical drum with hemispherical dome type shell at the top.
2. Grate: It is the platform on which the solid fuel is burnt.
3. Combustion Chamber: The burning of fuel takes place in the combustion chamber.
4. Fire Tubes: Cochran boiler has multi tubular fire tubes. The hot flue gases from the combustion chamber travels to the smoke box through these fire tubes. The fire tubes helps in the exchange of heat from the hot flue gases to the water.
5. Fire Hole: It is the hole provided to fire the fuel inside the furnace.
6. Furnace: It lies at the bottom of the boiler. Furnace is the place where all the fuel is burnt. Without furnace the working of this boiler is not possible.
Features of Cochran boiler are listed below:
- It is very compact and requires minimum floor area.
- Any type of fuel can be used with this boiler.
- It is well suited for small capacity requirements.
- It gives about 70% thermal efficiency with coal firing and about 75% with oil firing.
- The ratio of grate area to the heating surface area varies from 10: 1 to 25: 1.
Advantages of Cochran Boiler
(i) Low initial installation cost.
(ii) It requires less floor area.
(iii) Easy to operate and handle.
(iv) Transportation of Cochran boiler is easy.
(V) It can use all types of fuel.
Disadvantages of Cochran Boiler
(i) Low rate of steam generation.
(ii) Inspection and maintenance is difficult.
(iii) High room head is required for its installation due to the vertical design.
(iv) It has limited pressure range.
Applications of Cochran Boiler
- Variety of process applications in industries
- Chemical processing divisions
- Pulp and Paper manufacturing plants
- Refining units
Besides, they are frequently employed in power generation plants where large quantities of steam (ranging up to 500 kg/s) having high pressures i.e. approximately 16 mega-pascals (160 bar) and high temperatures reaching up to 550 °C are generally required.
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