What is Net stack temperature?

Asked By: Krystle Vinhanova | Last Updated: 21st March, 2020
Category: home and garden indoor environmental quality
4.4/5 (323 Views . 23 Votes)
The "net stack temperature" is the difference between the flue gas inside the chimney and the room temperature outside the burner. Net stack temperatures above 700oF (370oC) are in general to high. Typical values are between 330 - 500oF (160 - 260oC). High stack temperatures may be caused by. undersized furnace.

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Subsequently, one may also ask, what is stack temperature?

Stack Losses: Stack temperature is a measure of the heat carried away by dry flue gases and the moisture loss. The stack temperature is the temperature of the combustion gases (dry and water vapor) leaving the boiler and reflects the energy that did not transfer from the fuel to the steam or hot water.

One may also ask, what is the temperature of flue gas? 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.

Beside above, what could be the cause of a high stack temperature?

The most common cause of high stack temperatures is running with too much excess air. Not only will lowering the excess air reduce the stack temperature there will also be an increase in heat transfer in the radiant section of the furnace.

What is stack loss?

Stack losses typically are the largest single energy loss in boiler operations and involve both excess air and stack temperatures. The amount of heat lost will depend on the temperature and volume of gas leaving the boiler. Boiler efficiency is highly dependent on the excess air rate.

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What is the difference between chimney and stack?

As nouns the difference between chimney and stack
is that chimney is a vertical tube or hollow column used to emit environmentally polluting gaseous and solid matter (including but not limited to by-products of burning carbon or hydro-carbon based fuels); a flue while stack is (lb) a pile .

What causes stack effect?

The cause of stack effect is the difference in density between the cold, denser air outside the building and the warm, less dense air inside the building. When the temperature outside the building is warmer than the temperature inside the building, the stack-effect phenomenon is reversed.

How is net stack temperature calculated?

The "net stack temperature" is the difference between the flue gas inside the chimney and the room temperature outside the burner. Net stack temperatures above 700oF (370oC) are in general to high. Typical values are between 330 - 500oF (160 - 260oC).

How do smoke stacks affect the environment?

Smokestack Smoke and Air Pollution
Noxious gases include sulfur dioxide, nitrogen oxides, carbon dioxide, carbon monoxide and chemical vapors. Taller smokestacks reduce the impact of pollutants on the local area by spreading the released pollutants over a larger area.

What is stack pressure?

Stack effect or chimney effect is the movement of air into and out of buildings, chimneys, flue-gas stacks, or other containers, resulting from air buoyancy. Buoyancy occurs due to a difference in indoor-to-outdoor air density resulting from temperature and moisture differences.

What are smoke stacks for?

A smokestack, stack, or chimney is a tall vertical pipe or channel used by power plants to exhaust combustion gases into the air. This height disperses pollutants over a wider area in order to minimize their impact.

Why chimney is used in boiler?

Chimneys are typically vertical, or as near as possible to vertical, to ensure that the gases flow smoothly, drawing air into the combustion in what is known as the stack, or chimney effect. The height of a chimney influences its ability to transfer flue gases to the external environment via stack effect.

Are flue gases dangerous?

The gases that the boiler flue disperses outdoors, including carbon monoxide, are potentially harmful, which is why the regulations surrounding them are getting stricter. Boiler flue regulations ensure that the gases being expelled don't re-enter the home, which would instantly make the flue redundant.

What is stack temperature of boiler?

Flue Gas Temperature
"Stack temperature" or flue gas temperature measures the temperature of the combustion gases when they leave the boiler. If the flue gas temperature is high, it suggests the heat created by the boiler isn't being effectively used to generate steam.

How do you measure the height of a chimney?

Stack Height Calculation Stack height is calculated using following formula H = 14 (Q) 0. 3 H is height of Chimney Q = Quantity of fuel (kg/hr) x sulphur content (%) x 2 100 The sulphur content in the bagasse is negligible (around 0.1 %) as compared to Indian coal (maximum considered of 0.5%).

How is boiler efficiency calculated?

In order to calculate boiler efficiency by this method, we divide the total energy output of a boiler by total energy input given to the boiler, multiplied by hundred. GCV= Gross calorific value of the fuel.

What affects boiler efficiency?

Ambient Air Temperature A 40 degree variation in ambient temperature can effect efficiency by about 1%. ?Most boiler rooms are relatively warm. ?The relative percentage of each heat transfer within steam boiler is dependent on the type of steam boiler, the designed transfer surface, and fuels.

How can I increase the efficiency of my boiler?

Here are 15 easy tips to help make your boiler system more efficient and save money on your monthly bills:
  1. Lower the Stack Temperature.
  2. Install an Economizer.
  3. Tune the Burner Regularly.
  4. Install a Variable Frequency Drive.
  5. Insulate your Valves.
  6. Clean the Fireside.
  7. Preheat Combustion Air.
  8. Clean the Water Side.

Which reduces the efficiency of boiler to a greater extent?

Loss of Heat due to Moisture & Ash content in the fuel will decrease the boiler efficiency. The heat required for evaporating the moisture and bringing it to the flue gas temperature goes vain. Therefore moisture in fuel and also in combustion air has to be monitored and controlled carefully.

What is combustion efficiency?

Combustion efficiency is a measurement of how well the fuel being burned is being utilized in the combustion process. This is different from the efficiency number produced on the analyzer, which is reflective of the total amount of heat available from the fuel minus the losses from the gasses going up the stack.

What causes soot in furnace?

A lack of proper maintenance can lead to problems, such as soot production, inefficient operation, insufficient heating, clogged burners and a cracked heat exchanger. Clogged oil nozzles or gas orifices can lead to improper combustion, causing the formation of soot.

What should my flue temp be?

A good rule of thumb is to get the temperature up to a stovepipe thermometer reading of 450 degrees F. for the first half-hour, and to keep it at an average of 300 degrees thereafter, each day that you start your stove.