Khulna University of Engineering & Technology

Presentation on Cochran boiler

Submitted By : Himadri Sen GuptaRoll: 1311004

Cochran Boiler :

This boiler is a vertical, multi tube, fire tube, internally fired, natural circulated ,stationary and a low pressure boiler.

It is a modification of simple vertical boiler where heating surface is being increased by number of fire tubes .

Improvement over the simple vertical boiler as it provides greater heating surface.

Specification : Shell diameter: 2.75m, height 5.75m heating surface area 120m², working pressure 6.5bar (max 15bar), steam capacity 3500kg/hr (max capacity

4000kg/hr), efficiency 70% to 75%.

Characteristics

Straight tube Boiler  Low pressure Boiler Single tube Boiler Natural draft Boiler Natural circulation Boiler Stationary Boiler Internally fired Boiler     Water tube Boiler Coil fired Boiler Multi tube Boiler Vertical Boiler

Parts of Cochran Boiler:

1.Ash pit:Ash pit contain the ashes of the fuel material after the complete combustion.

2. GrateGrate contain the fuel for combustion

3. Feed check valveFeed check valve is used to check the level of fuel material inside the grate

4. Fire holeFire hole is used to introduce the initiating fire spark

5.Flue pipeFlue pipe take the hot gases from the hemispherical crown and move it toward the combustion chamber.6. Fire brick liningFire brick lining make sure that heat remain inside and outer side remain cool.7. Smoke boxSmoke box contain the smoke of burnt gases which come from the fire tubes8. Water level indicatorIt indicates the water level inside the water tank.9. External shellOuter shell which is visible to us.10. Pressure gaugeIt indicates the steam pressure inside the boiler

11. Safety valveUse to prevent the establishing of over pressure inside the boiler.12. Stop valveUse to stop the outgoing of steam from the boiler13. ChimneyTake the smoke from the smoke box and throw it out in the atmosphere.

Working of the Cochran boiler:

All the fuel is place in grate and combustion get started. Hot gases along with some unburnt gases moves from hemispherical

crown into the combustion chamber where all the unburnt gases are burn out to produce the heat.

Hot gases moves into the tubes there they exchange their heat with the liquid.

After moving in the tubes gases in the shape of smoke came out into the smoke chamber from where it moves out through the chimney.

Steam produce is collected into the upper chamber and after the sufficient pressure steam is released toward the use full purpose.

Advantages:

The minimum floor area is required. Cost of construction is low. it can be moved and stet up take it to different location. Boiler has self contained furnace . No brick work setting is

necessary. Any type of flue can be used.

Disadvantages:

Steam raising capacity is less due to vertical design. Difficult in cleaning and inspection due to vertical design. The capacity and pressure are limited. The boiler requires high head room. 

Thank you