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Today, This blog post will guide on the Cochran Boiler which includes its definition, parts, and construction, working along with its advantages and disadvantages, and much more down the road.
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What is Cochran Boiler?
A cochran boiler is a vertically placed, natural circulation, low-pressure, internally fired, multitube, firetube boiler.
This is a type of boiler which contains horizontally placed multiple fire tubes which greatly enhances the efficiency of this boiler.
Let me tell you that the Cochran boiler is an extended version or modified version of a simple vertical boiler.
Parts and Construction of the Cochran Boiler-
These are the major parts or Boiler’s Mounting and Accessories of this boiler and they are-
- Fire door
- Ash Pit
- Flue Pipes
- Combustion Chamber
- Smoke Box
- Man Hole
- Anti-Priming Pipe
The grate is the place of fuel placing which holds the fuel and it is made up of iron and divided into segments to blow the fuel and further help to fall the ash beneath into the ashpit.
The grate is situated at the lower portion of the boiler just above the ashpit.
2. Fire Door-
The fire door is a kind of gate which is used to put the fuel onto the grate. A fire door is installed in front of the boiler at the lower section.
Ashpit is used to collect ashes falling from the grate and it is situated at the bottom of the boiler just below the grate.
4. Flue pipes-
As the name suggests, It transmits the hot flue gases from the furnace to the combustion chamber. Flue pipes are attached to the furnace and open in the combustion chamber.
5. Combustion Chamber-
This boiler’s combustion chamber is surrounded by bricks to minimize the temperature and further help to maintain the overheating problem around the combustion chamber.
The combustion chamber is assembled in the middle of the boiler just beside the fire tubes facing the front end.
Smokebox is the chamber to store and releases the used hot flue gases coming from the fire tubes, as per need.
The smoke box is located behind the boiler just beneath the chimney and just beside the firetubes.
7. Man Hole-
Manhole is a place where maintenance and repair of the boiler are done. This manhole is located just below the top.
8. Anti-Priming Pipe-
Dry steam is extracted through this pipe and this is located at the top of the boiler.
Mountings of the Cochran Boiler-
There are several parts used to support this boiler and they are-
- Water level Indicator
- Pressure gauge
- Safety Valve
- Steam stop valve
- Blow-off cock
1. Water-Level Indicator-
As the name suggests, This device is used to indicate the water level in the boiler and further, it indicates if water goes below the desired limit.
This is located just above the center of the boiler and can be seen from the front end of the boiler.
2. Pressure Guage-
This device is used to measure the pressure of the boiler and it is located just below the top of the boiler.
3. Safety Valve-
A safety valve is used to prevent the boiler from bursting by blowing off when the pressure goes beyond the desired limit. This device is located at the top of the boiler.
4. Steam Stop Valve-
This device is used to manage the steam flowing from the boiler to outside where dry steam is needed. This device is also located at the top of the boiler.
5. Blow-off Cock-
This device is used to drain the mud and sedimentation collected from the water running inside the boiler. This device is usually located at the bottom of the boiler.
Working of the Cochran Boiler-
- Water is filled through the feed check valve up to the desired limit and then fuel is placed onto the grate in the furnace chamber.
- Now, an initial spark is provided to burn the fuel placed on the grate and further air is blown which helps in the complete combustion of fuel in a consistent manner.
- When full combustion of fuel is took place, the hot gas or flue gas is now started to move toward the combustion chamber through the flue pipes.
- Now, these hot flue gases enter into the firetubes and further heat up the firetubes.
- As water is surrounded by the firetubes, the heat exchange takes place and further starts to heat the water.
- As heating of water further generate steam and this generated steam is collected at the top hemispherical shape of this boiler.
- Now, this formed steam has some percentage of moisture which is further removes through the anti-priming pipe and now dry steam is sent to the steam stop valve.
- From the steam stop valve, steam is transformed to the desired location where steam is needed.
- Now, the exhaust hot flue gases are collected into the smokebox and further released into the atmosphere via a chimney.
- Ash of the burned fuel is collected into the ashpit located below the grate.
- This is how the Cochran boiler works.
Characteristics of Cochran Boiler-
- A vertical boiler
- Internally fired boiler
- Naturally circulated boiler
Specification of the Cochran Boiler-
- Shell diameter- 2.75meters
- Height- 5.75meters
- Heating surface area- 120m2
- Working Pressure- 6.5 bar
- steam Capacity- 3500kg/hr
- Efficiency- 70 to 75%
Advantages of Cochran Boiler-
- Low floor area is required
- The initial cost of installation is low
- Easy to operate
- flexible design
- Portable Boiler
- any kind of fuel can be used
Disadvantages of Cochran Boiler-
- Low steam generation rate
- Low-pressure boiler
- Regular maintenance is needed
- A high head area is required due to the vertical design of the boiler
Applications of Cochran Boiler-
- Paper Mills
- Chemical Industries
- Textile Industries
- Pulp Mills
- Used in Marine applications just like a scotch marine boiler
- Food processing Industries
I just have this to say about the Cochran boiler. I tried to cover every aspect of this boiler, If I missed anything, please let me know in the comment section below.
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Abhishek Tiwary is a blogger by passion and a Quality Engineer by profession. He completed his B.Tech degree in the year 2017. Now working in a reputed firm. He loves to share his knowledge with others.