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.
How does a 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”.
Is stack gas the same as 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).
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.
Why are stacks painted red and white?
Generally, the towers must be painted intermittently in white and red/orange to make them visible during the day, with paint tones (including white) specifically and precisely mandated by the federal regulations.
What is the temperature of flue gas?
Currently, the minimum flue gas temperature for boilers is equal to 120-130 °C. in this temperature of leaving gases eliminates the condensation in the flues and smoke stacks, natural draught increases. However, in many boilers the actual temperature of the flue gas is equal to 180 – 200 °C.
What is a boiler stack?
Concept. A stack economizer is an exchanger designed to recover the heat contained in the hot flue gases from boilers; the heat is transferred to a hot water system. In the case of a steam boiler, about 20% of the energy required for the burner ends up in the flue, often at high temperatures.
What is boiler stack 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. These methods are designed to recover heat for the boiler system.
What is boiler flue gases?
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.
How do you calculate flue gas composition?
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.
How do you calculate gas stack velocity?
To determine the velocity profile, the average gas velocity and volumetric flow rate in a stack or duct. The method is based on the measurement of the velocity pressure heads and stack gas temperatures. It takes into consideration the stack gas molecular weight, pressure and the configuration of the stack or duct.
What is the density of flue gas?
Pressure drop calculator, download version preview
| Temperature [OC] | cp [kJ/kgK] | ρ [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 |
Where was the first flue gas stack built?
Most 18th-century industrial chimneys (now commonly referred to as flue gas stacks) were built into the walls of the furnace much like a domestic chimney. The first free-standing industrial chimneys were probably those erected at the end of the long condensing flues associated with smelting lead .
How are flue gases produced in a chimney?
A flue-gas stack, also known as a smoke stack, chimney stack or simply as a stack, is a type of chimney, a vertical pipe, channel or similar structure through which combustion product gases called flue gases are exhausted to the outside air. Flue gases are produced when coal, oil, natural gas,…
Why are packaged firetube boilers designed that way?
This will avoid many problems that are too often considered combustion related but are really system generated, resulting from improper flue gas breeching and stack design. Packaged firetube boilers are designed to operate at their peak performance with short, straight flue stacks.
How does the exhaust stack affect the boiler?
Firetube boiler and burner packages with the exhaust stack and breeching attached to them operate as a system. Each item affects how well the other items perform their task. Refinements in combustion technology and burner designs have made it more critical that everyone reviews the total system to ensure proper operation.