What is the function of flue gases?

What is the function of flue gases?

Flue gasthe emitted material produced when fossil fuels such as coal, oil, natural gas, or wood are burned for heat or powermay contain pollutants such as particulates, sulfur dioxide, mercury, and carbon dioxide.

What is flue gas made of?

Flue gases are a mixture of combustion products including water vapor, carbon dioxide, particulates, heavy metals, and acidic gases generated from direct (incineration) or indirect (gasification and pyrolysis) oxidation of RDF or intermediate syngas.

What is the advantage of using flue gas inside a boiler?

What is the advantage of using flue gas inside a boiler? Explanation: Using flue gas to heat up the water tubes reduces the greenhouse effect indirectly by making use of its heat to turn the water in water tubes into steam. This will be used in steam power plant to rotate the turbine and to produce electricity.

Do gas boilers need a flue?

Regular, combi and system boilers are all fitted with flues. In fact, the only type of boiler which doesn’t have a flue is a back boiler, which used to be situated behind fireplaces. However, back boilers are increasingly rare these days and most homeowners choose to have them updated.

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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).

What is the temperature of flue gas?

According to an FGD manufacturer, the optimal flue gas temperature for a desulfurization process is approximately 149F (65C). Cooling of the flue gas to the saturation temperature occurs in a spray area, and the flue gas leaves the FGD reactor at a temperature close to the saturation temperature.

Is flue gas flammable?

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 is flue gas cleaned?

An important part of flue gas purification is the removal of particulates from the exhaust gas. These dusts are partly produced during the incineration process, but also by the individual components of the flue gas cleaning process – such as the spray absorber, by spraying activated carbon and lime milk.

Is flue gas homogeneous?

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

What is the importance of analysis of flue gas?

Flue gas analysis will give you an indication of whether or not you are achieving maximum possible carbon combustion in your fuel. You can also analyse your flue gas in order to determine environmental impact and whether you are maintaining compliance with local emissions regulations.

What is the pH value of water permissible for boiler?

Boiler pH. Natural water is usually between 6.5 and 7.5 pH. A common recommendation is to maintain boiler water at 8.5 pH.

Which of the following is used to heat the feed water by using flue gases?

Economizer Explanation: Economizer: It is also known as a feedwater heater. It is a device in which the waste heat of the flue gases is utilized for heating the feed water.

Where should a boiler flue be placed?

Depending on the size of the boiler, the flue must be positioned a certain distance from the nearest window, door, or air brick. Typically this is around 30-60cm if it’s to the side or above the opening, and a bit more if it’s below.

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When should I replace my boiler flue?

Yes, you do need to replace the flue when replacing any boiler even if the same brand. This is to keep it in line with manufacturers specifications and Building regulations. The washers on the combustion side of the flue (inner section) perish over time and can leak and cause damage to the rest of the flue.

Where is the boiler flue?

Where is your boiler flue? It’s most likely your boiler flue will be exiting the side of your house, through the wall which is nearest to your boiler. You’ll probably have noticed steam coming from it and your neighbours especially when the air outside is colder. This is commonly referred to as a horizontal flue.

How do you calculate flue gas?

Composition of the dry flue gas from the stoichiometric combustion of 1 kg of biomass: N2 from theoretical air = 4.94 0.79 = 3.90 m3. N2 from biomass = 0.001 0.224 = 0.0002 m3. CO2 from biomass = 4.33 0.224 = 0.97 m3.

What is the density of flue gas?

Pressure drop calculator, download version preview

Temperature [OC] cp [kJ/kgK] [kg/m3]
0.0 1.042 1.295
100.0 1.068 0.95
200.0 1.097 0.748
300.0 1.122 0.617

Which is correct way of flue gases flow?

It is generally placed after the economizer; so that the flue gases pass through the economizer and then to the air preheater.

How do you control flue gas?

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 is flue temperature measured?

A probe meter is the only way to measure flue gas temps. As to what temps are proper well, below 400 you’ll be making creosote too fast since you need the flue gas to be hot enough at the top of the chimney to have not condensed the liquid out of it yet.

How do you compress flue gas?

Flue gas condensation is a process, where flue gas is cooled below its water dew point and the heat released by the resulting condensation of water is recovered as low temperature heat. Cooling of the flue gas can be performed either directly with a heat exchanger or indirectly via a condensing scrubber.

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How much co2 is in a flue gas?

Typical flue gases from natural gas-fired power plants may contain 8-10% CO2, 18-20% H2O, 2-3% O2, and 67-72% N2; typical flue gases from coal-fired boilers may contain 12-14 vol% CO2, 8-10 vol% H2O, 3-5 vol % O2 and 72-77% N2.

What causes high CO in a boiler?

If the oxygen level is set too low and something changes the combustion process can become ‘fuel rich’ as there is insufficient oxygen for all the fuel to burn. This can cause high levels of CO to be generated and in the extreme enough fuel to enter the boilers flue and ignite (explode) outside the combustion chamber.

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.

How effective is flue gas scrubbing?

For a typical coal-fired power plant, FGD systems will remove ~95% of the SO2 in the flue gases. FGD predominantly employs two methods of filtering the emissions (dry or wet scrubbing) for coal-burning plants to be in compliance with regulations mandated by the EPA’s Effluent Limitation Guidelines (ELG).

What is flue gas analysis?

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.

Why is desulphurization important?

These processes are of great industrial and environmental importance as they provide the bulk of sulfur used in industry (Claus process and Contact process), sulfur-free compounds that could otherwise not be used in a great number of catalytic processes, and also reduce the release of harmful sulfur compounds into the …