# What are the factors to be considered for the flue gas stack designing?

## What are the factors to be considered for the flue gas stack designing?

Factors that go into designing a flue gas stack include its height and diameter, the amount of combustion air required, and the temperature of the gas after it is outside the combustion zone.

### Why are power plant stacks so tall?

Tall smokestacks—stacks of 500 feet or higher, which are primarily used at coal power plants—release air pollutants such as sulfur dioxide (SO2) and nitrogen oxides (NOx) high into the atmosphere to help limit the impact of these emissions on local air quality.

What is the difference between chimney and stack?

Explanation: The chimney is the whole thing, the stack is the part that sticks out (above the roof, usually).

How do you calculate flue of a gas?

As shown in Figure 1.1, the dry stoichiometric flue gas flow rate (m3/s) is obtained by multiplying the heat release (MW) by a fuel factor (m3/MJ).

## 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.

### Why are stacks red and white?

The paint or fiberglass inserts commonly used are white. The color seems appropriate because of it’s reflective index which prevents absorption of solar radiation keeping the external tower cooler. Towers are commonly painted red and white to increase their visibility, which is a good precaution for aircraft.

How is stack height selected?

TVA’s choice of stack heights has been based largely on (1) a consideration of environmental, design, and opera- tional factors for each site, (2) an accu- rate definition of dispersion from each of its previous and usually somewhat smaller plants, and (8) extrapolation of these data to a larger new plant with …

How do you create a stack height?

Calculating Effective Stack Height Wind Speed

1. Ua = wind speed at altitude Za, m/s.
2. H = effective stack height, m.
3. Za= height above surface, m (usually 10 meters)
4. p = exponent is a function of atmospheric stability class.

## What is the height of chimney?

The most common of these being the 2 foot, 10 foot, 3-foot rule. Roughly this means that a chimney should be 3 feet higher than the point it passes through a roof, while also being at least 2 feet taller than any part of a building that’s within 10 feet of the chimney.

### How does flue gas stack work?

Flue-gas stack draft 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 movement or flow of combustion air and flue gas is called “natural draft”, “natural ventilation”, “chimney effect”, or “stack effect”.

How is boiler flue gas flow calculated?

Most power plants calculate flue gas flow rate from the net energy consumption derived from the fuel flow multiplied by the Net Calorific Value (NCV). Alternatively, the power or heat output is divided by the electrical or thermal efficiency, as appropriate, in order to determine the net energy consumption.