Flue gas treatment technologies are post-combustion processes to convert NOx to molecular nitrogen or nitrates. The two primary strategies that have been developed for post-combustion control and are commercially available are selective catalytic reduction (SCR) and selective non-catalytic reduction (SNCR).

How do you test for flue gas?

Flue Gas Analysis is performed by inserting a probe into the flue of the furnace, boiler, etc., between the last heat exchanger and draft diverter or any source of make-up air that could enter the flue that did not pass through the combustion process. This is known as ‘in-situ’ testing.

Which of the following does not work with the help of flue gases?

Explanation: In boiler operation the Injector is used to feed water into the boiler and superheater, economiser, preheater are related to the flue gas operation. Injector: The function of the injector is to feed water into the boiler and thus it is not related to flue gas operation.

What cools down the flue gas?

Cooling of the flue gas can be performed either directly with a heat exchanger or indirectly via a condensing scrubber. The condensation of water releases more than 2 gigajoules (560 kWh) per ton of condensed water, which can be recovered in the cooler for e.g. district heating purposes.

How do you inspect a flue pipe?

1. Remove the flue cap to check for blockages such as debris or birds’ nests.
2. Replace and secure the cap tightly to the end of the flue pipe. …
3. Look for signs of blockages by examining the pipe itself – water streaks or rust on the flue pipe may indicate a blockage, causing moisture to back up.

How do you reduce the temperature of a gas flue?

Using an integrated or downstream economiser, the flue gas temperature can be reduced to 120 – 140°C, depending on the economiser design, which reduces the flue gas loss significantly. During this process, the heat in the flue gases is transferred to the boiler feed water flowing in countercurrent.

What would the flue gas symptoms be if there were too much airflow?

Too much excess air leads to lower flame temperature. That means less heat gets into the system. Also, excess air must heat up to flue gas temperature, which consumes extra energy.

How do you get water out of flue gas?

Use a desiccant to absorb the water. Another method is to use a desiccant to absorb the water. Flue gas passes through a liquid spray in an absorber tower. The desiccant absorbs the water.

At what temperature do flue gases condense?

Flue gas will form and condense on a heat exchanger and in the boiler stack when it falls below its dew point, and this occurs when the return water temps of the system are around 135°F.

Why is it called flue gas?

Flue gas (sometimes called exhaust gas or stack gas) is the gas that emanates from combustion plants and which contains the reaction products of fuel and combustion air and residual substances such as particulate matter (dust), sulfur oxides, nitrogen oxides, and carbon monoxide (Table 3.7).

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Can flue gas be reused?

The flue gas can be recycled back to the furnace in either a wet or a dry stream.

Is flue gas flammable?

Quite often, the flue gas refers to the combustion exhaust gas produced at power plants. … Since ambient air contains about 79 volume percent gaseous nitrogen (N2), which is essentially non–combustible, the largest part of the flue gas from most fossil-fuel combustion is uncombusted nitrogen.

How do I know if I have a blockage flue?

1. Oxidization – Use a cloth to determine if there are any white stains around the connection of the flue as these can indicate a blockage.
2. Take a look – Some blockages will be visible from the outside, particularly in the case of garden debris.

What is flue blockage?

They are a way for combustion fumes that have been created by your boiler to be released outside the home. If your boiler’s flue becomes blocked, these gases have nowhere to go other than back inside your home. … However, a blocked flue can mean the gases become trapped in your home, causing you to breathe them in.

How do you seal a furnace flue pipe?

1. Brush away any dirt or dust from the area around the furnace vent that you will be sealing.
2. Cut the tip of a caulk tube with a utility knife. …
3. Inject the silicone caulk into the gap between the vent and the side of the house or foundation. …
4. Brush the area to be sealed with a stiff bristle brush.

What is the most likely cause of flames that are lifting off the burner?

What is the most likely cause of flames that are lifting off the burner? Too much primary air.

What happens if there is improper venting of the furnace?

Combustion byproducts, such as carbon monoxide, can lead to many ill effects. This includes headaches, dizziness, nausea, fatigue, and even death. When your furnace has a blockage or backdraft and cannot properly vent, combustion gases cannot escape.

What could result if a flame is adjusted with too much primary air?

The gas flame will lift off the burner and be noisy if it receives too much primary air. … Flame is air starved. The flame in a gas fired furnace is burning with heavy yellow tips.

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.

What is flue temperature?

The flue temperature plays an important role because an increase in the mean flue temperature (MFT) over a range between 1165 and 1390 °C –to produce carbonization rates of 20, 25, and 30 mm/h, respectively-, significantly modifies the yield, properties, and composition of the by-products.

How is flue gas generated?

Flue gas—the emitted material produced when fossil fuels such as coal, oil, natural gas, or wood are burned for heat or power—may contain pollutants such as particulates, sulfur dioxide, mercury, and carbon dioxide. Most flue gas, however, consists of nitrogen oxides.

What causes flue gas condensation?

What causes the condensation in a boiler flue? … With more heat entering the process there is less heat exiting out the boiler flue. The water vapor formed during the combustion is less likely to remain a vapor. As the temperature of the flue gas cools below “Dew Point”, the water changes state to a liquid.

How do you stop flue condensation?

Here is the bottom line: The only way to avoid sustained flue gas condensation is to monitor the boiler’s inlet water temperature and react to that temperature by limiting the rate at which heat moves from the boiler into the distribution system.

Is flue gas acidic?

Condensation of flue gas produces an acidic solution containing concentrations of nitric, nitrous, sulfuric, and sulfurous and hydrochloric acids. These acids can become more concentrated by repeated condensing and evaporation on heat exchangers and flues.

What is the composition of flue gas?

Flue gases are a mixture of combustion products and include water vapour, carbon dioxide, particulates, heavy metals and acidic gases.

What is boiler flue gas?

Flue gas refers to a chemical byproduct substance that is generated as a result of a combustion reaction that has escaped through long pipes such as those in boilers, furnaces or steam generators. Flue gas may also be referred to as exhaust gas and may act as a reactor agent for atmospheric corrosion.

What are the three by products of perfect combustion?

2.3. Complete combustion of hydrocarbons (without impurities) in the presence of enough oxygen produces water vapor and carbon dioxide.

What is the difference between fuel gas and flue gas?

Flue gas is the gas exiting to the atmosphere via a flue, which is a pipe or channel for conveying exhaust gases from a fireplace, oven, furnace, boiler or steam generator. Quite often, the flue gas refers to the combustion exhaust gas produced at power plants.

Is flue gas homogeneous?

Statement (II): Flue gases can be treated as a homogeneous mixture of gases.

What could be blocking my chimney?

• There are three main causes of chimney blockages:
• An excessive build-up of soot or creosote (tar)
• Birds, squirrels, or other small animals nesting in the chimney.
• The collapse of the internal chimney bricks/tiles.

Can a chimney get clogged?

Both traditional chimneys and vent pipes on wood stoves can become clogged over time. Anything that obstructs the flow of air and smoke is a problem, but a buildup of creosote is a dangerous problem.