PowerPoint Presentation On Flue Gas System

PPT On Flue Gas System

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Flue Gas system Air pre Heater Presentation Transcript:

1. Presentation Plan
Air heaters
Types of air heaters
Materials Used
Sealing arrangement for air heaters
Air heater Performance
Performance tests

2. AIR PRE HEATER
APH is the last heat exchanger in the boiler flue gas circuit. To achieve maximum boiler efficiency maximum possible useful heat must be removed from the gas before it leaves the APH. However certain minimum temperature has to be maintained in the flue gas to prevent cold end corrosion

3. Air Pre-Heater-functions
An air pre-heater heats the combustion air where it is economically feasible.
The pre-heating helps the following:
Igniting the fuel.
Improving combustion.
Drying the pulverized coal in pulverizer.
Reducing the stack gas temperature and increasing the boiler efficiency.
There are three types of air heaters:
Recuperative
Rotary regenerative
Heat pipe

4. Advantages by use of APH
Stability of Combustion is improved by use of hot air.
Intensified and improved combustion.
Permitting to burn poor quality coal.
High heat transfer rate in the furnace and hence lesser heat transfer area requirement.
Less un-burnt fuel particle in flue gas thus combustion and both r efficiency is improved.
Intensified combustion permits faster load variation and fluctuation.
In the case of pulverised coal combustion, hot air can be used for heating the coal as well as for transporting the pulverised coal to burners.
This being a non-pressure part will not warrant shut-down of unit due to corrosion of heat transfer surface which is inherent with lowering of flue gas temperature.

5. Types Of Air Preheater
Recuperative
Regenerative
Plate type Airheater
Steam Air Preheater
Langsdorm type
Rothemuhle type
Tri sector Air Heater

6. Rotary Plate (Regenerative) type Pre-Heater
Rotates with a low speed : 0.75 rpm.
Weight : 500 tons.
This consists of : rotor, sealing apparatus, shell etc.
Rotor is divided into 12 or 24 sections and 12 or 24 radial divisions.
Each sector is divided into several trapezoidal sections with transverse division plates.
Heat storage pales are placed in these sections.

7. The Material used in APH for heat storage
Material used Cold end in the basket is a special type of steel (corten steel (trade name)) which has high resistance to the low temperature sulphur corrosion, thus prolonging operational life.
In the hot end mild steels are used
The optimal geometric shape is usually corrugated and sizes are determined based on design modelling and experimental data. The turbulence of air and gas flow through the package increases the heat transfer rate.

8. For more please refer our PPT. Thank You.