What is flue gas temperature?
The typical furnace outlet temperature of flue gases is usually around 1200 °C which will decreases gradually along the pathway of heat transfer, while the temperature of the flue gases going to stack is around 150 °C.
At what temperature does the flue gas travel through the generator?
The steam piping (with steam flowing through it) is directed through the flue gas path in the boiler furnace. This area typically is between 1,300–1,600 °C (2,372–2,912 °F).
What are the advantages of using pulverized coal in boilers?
Advantages of pulverized coal It increases the efficiency of the boiler. It makes possible the use of wide variety of coal. It reduces time of raising temperature of steam. Combustion of pulverized coal can readily be adopted to automatic control.
What is pulverised fuel firing?
Pulverised-fuel (PF) technology is widely used for large coal-fired power plants. In such systems, the fuel particles are injected pneumatically at high velocity (the primary air is used as a carrier) through a burner nozzle into the furnace (Fig.
What is the ignition temperature of coal?
2.10. 3 Start-Up Procedure. Because the ignition point of coal is around 300°C, there should be another ignition source to start the firing.
Why do flue gases leave the stack at high temperature?
The combustion flue gases inside the flue gas stacks are much hotter than the ambient outside air and therefore less dense than the ambient air. That causes the bottom of the vertical column of hot flue gas to have a lower pressure than the pressure at the bottom of a corresponding column of outside air.
How do you reduce stack temperature?
Stack losses can be minimized by reducing excess air‚ which reduces the quantity of flue gas that is heated to exhaust temperature (FGT)‚ and by reducing the exhaust temperature.
Which is disadvantage of using pulverized fuel?
Disadvantages of Pulverized Coal Firing The initial investment in pulverized coal firing system is more compared to solid firing system. The running cost is also higher. The pulverized coal produces fly ashes. Removal of ash grain from the exhaust gases is always expensive as it requires an electrostatic precipitator.
What is a need of use of pulverized coal?
Pulverized coal firing ensures complete combustion of coal, thus ensuring higher efficiency of steam generators. It is predominantly adopted in large coal-fired utility boilers. The finer the grinding of coal, the more efficient its combustion.
How is coal pulverized?
Pieces of coal are crushed between balls or cylindrical rollers that move between two tracks or “races.” The raw coal is then fed into the pulverizer along with air heated to about 650 °F (340 °C) from the boiler. The powdered coal from the pulverizer is directly blown to a burner in the boiler.
Why pulverized fuel is preferred?
How is flue gas cooled in a coal boiler?
Flue gas was cooled down to 150 °C before entering the fabric filter, and the dust-free RFG was divided into primary RFG, which after water removal was preheated and used to dry and transport the pulverized coal, and the secondary RFG, which was fed to the boiler.
How does a pulverized coal fired boiler work?
In coal-fired installations, high-sulphur coals containing an READ MORE A pulverized coal-fired boiler is an industrial or utility boiler that generates thermal energy by Coal is ground to the size of a fine grain, mixed with air and burned in the flue gas flow. of controlling the pulverized coal’ READ MORE
How is flue gas used in a power plant?
In the power plant, there are two separate boilers, both equipped with flue gas cleaning systems that include electrostatic precipitators, semi-dry desulphurization, and fabric filters, in the given order after the boiler. Boilers (363 MWth) are equipped with a reheater and utilizes the natural circulation of flue gas.
Where does coal ash settle in a boiler?
Coal ash may either settle out in the boiler (bottom ash) or entrained in the flue gas (fly ash). The distribution of ash between the bottom ash and fly ash fractions directly affects the PM emission rate and depends on the boiler firing method and furnace type (wet or dry bottom).