How do you reduce the temperature of a gas flue?

How do you reduce the temperature of a gas flue?

The temperature of the flue gas leaving the boiler is commonly reduced in an air preheater (APH) when the sensible heat in the flue gas leaving the economizer is used to preheat combustion air.

What cools down the 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.

Does flue gas include water?

The boiler flue is essentially the boiler’s chimney, but instead of smoke and soot being channelled away from the inside of the home, it’s mainly carbon dioxide and water vapour that’s emitted. It’s the reason all households should have a carbon monoxide alarm as well as a smoke alarm.

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.

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.

At what temperature does the flue gas travel through the generator?

The superheater works like coils on an air conditioning unit, however to a different end. 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 is the difference between dry flue gas loss and wet flue gas loss?

The dry flue gas loss accounts for the heat lost up the stack in the “dry” products of combustion, that is, CO2, O2, N2, CO and SO2. These carry away only sensible heat, whereas the “wet” products, mainly moisture from the combustion of hydrogen, carry away both latent and sensible heat.

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.

What is the difference between flue gas and fuel 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.

What temperature is flue condensate?

What’s more, condensing occurs naturally – when the vapors cool below their dew point, which is typically 135°F. By flowing cold water (<130°F) into the heat exchanger, AERCO boilers and water heaters automatically begin to condense to yield greater efficiencies.

What is the main reason for not reducing the temperature of boiler flue gas below 120 C?

Usually we consider cooling up to the ambient temperature unless there are technical limitations; for example flue gases from diesel industrial boilers are not cooled below 120°C for avoiding condensation of water vapor and the production of sulfuric acid [2] . …

What is the ideal CO2 content of flue gas?

approximately 10%
Carbon dioxide – CO2 – is a combustion product and the content of CO2 in a flue gas is an important indication of the combustion efficiency. Optimal content of carbon dioxide CO2 after combustion is approximately 10% for natural gas and approximately 13% for lighter oils.

How does flue gas get into the atmosphere?

The steam generators in large power plants and the process furnaces in large refineries, petrochemical and chemical plants, and incinerators burn considerable amounts of fossil fuels and therefore emit large amounts of flue gas to the ambient atmosphere.

What kind of process is flue gas recirculation?

Flue Gas Recirculation (FGR) is the process of taking a portion of the flue gas from a combustion process and recirculating it back through a boiler or burner. When the process is used in internal combustion engines it is commonly referred to as exhaust gas recirculation (EGR).

How is flue gas used to reduce NOx?

In order to reduce NOx, recirculated flue gas must be mixed with air before entering the burner or cylinder. This is somewhat different than the temperature control setup, where flue gas in blown directly into the boiler. Thus, while FGR is effective for both boiler temperature control and NOx reduction, they require different injection points.

Why is flue gas used in a steam boiler?

Boilers run at a range of fuel rates but need to produce steam at a constant temperature. Heat transfer rates are low at lower fuel rates, producing cooler steam from the superheater. Recirculating flue gas effectively counteracts this problem by increasing the flow rate, and thus heat transfer, through the superheater coils.