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Sunday, September 23, 2012

PowerPoint Presentation on BOILERS FUNDAMENTALS


BOILERS FUNDAMENTALS Presentation Transcript:
In early 19th Century boiler were low pressure
Invention of water tube removed the pr barrier and boiler pr rise to super critical
Between 70- 90 utility operated conservatively and used low steam pr in boiler .
Now renewed interest in high efficiency supercritical boiler .The interest arose from the environmental need to attain higher efficiency and dividend of higher eff is reduce CO2

2. Boiler/ steam generator
Steam generating device for a specific purpose.
Capable to meet variation in load demand
Capable of generating steam in a range of operating pressure and temperature
For utility purpose, it should generate steam uninterruptedly at operating pressure and temperature for running steam turbines.

3. Basic Knowledge of Boiler
Water side then water cycle explained by other , air cycle , from where each comes explain it Phenomenological Model: Combustion is happening , heat transfer is happening , how heat is exchanged ,how heat is being

4. Drum
The boiler drum forms a part of the circulation system of the boiler. The drum serves two functions, the first and primary one being that of separating steam from the mixture of water and steam discharged into it. Secondly, the drum houses all equipments used for purification of steam after being separated from water. This purification equipment is commonly referred to as the Drum Internals.

5. Waterwall construction
Made of carbon steel (Grade-C) hollow circular tubes and DM water flows inside
Waterwalls are stiffened by the vertical stays and buck stays to safeguard from furnace pressure pulsation & explosion/ implosion
The boiler as a whole is hanging type, supported at the top in large structural columns.
Vertical expansion is allowed downwards and provision is made at bottom trough seal near ring header.

6. Superheater & Reheater
Heat associated with the flue gas is used in superheaters & Reheater, LTSH, economiser.
Maximum steam temperature is decided by the operating drum pressure and metallurgical constraints of the turbine blade material.
Reheating is recommened at pressure above 100 ksc operating pressure. Reheating is done at 20-25% of the operating pressure.
Carbon steel, alloy steel & SS used for tubing of SH & RH.

7. Steam Theory
Within the boiler, fuel and air are forced into the furnace by the burner.
There, it burns to produce heat. From there, the heat (flue gases) travel throughout the boiler.
The water absorbs the heat, and eventually absorb enough to change into a gaseous state - steam.
To the left is the basic theoretical design of a modern boiler.
Boiler makers have developed various designs to squeeze the most energy out of fuel and to maximized its transfer to the water.

8. Properties of Steam
Liquid Enthalpy
Liquid enthalpy is the "Enthalpy" (heat energy) in the water when it has been raised to its boiling point is measured in kcal/kg, its symbol is hf Also known as "Sensible Heat”
Enthalpy of Evaporation
It is the heat energy to be added to the water in order to change it into steam. There is no change in temperature, the steam produced is at the same temperature as the water from which it is produced. Also known as latent heat and its symbol is hfg

9. The temperature at which water boils, also called as boiling point or saturation temperature (It increases as the pressure increases. )
As the steam pressure increases, the usable heat energy in the steam (enthalpy of evaporation), which is given up when the steam condenses, actually decreases.
The total heat of dry saturated steam or enthalpy of saturated steam is given by sum of the two enthalpies hf +hfg
When the steam contains moisture the total heat of steam will be hg = hf +q hfg where q is the dryness fraction.

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

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