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How to calculate the flue gas flow rate of a boiler?
1. The first step in determining the boiler flue gas flow rate is to understand the boiler model and the heat generation of the fuel used. Zheng limb 2. For gas boilers, the calculation formula for flue gas flow rate is: flue gas flow rate=flow rate of carbon dioxide and water vapor produced by natural gas combustion+flow rate of unburned nitrogen+flow rate of excess air
3. The calculation method for flue gas flow rate of coal-fired boilers is similar to that of gas boilers, and Changqiao needs to consider the products of fuel combustion and the issue of excess air during the combustion process.
2. How to calculate the flue gas flow rate of a boiler? To calculate the flue gas flow rate of a boiler, it is necessary to determine the boiler flue gas volume based on the boiler model and fuel calorific value. If it is a gas boiler, the calculation method for the hood of the boiler is as follows: the flue gas flow rate of the gas boiler=the flow rate of carbon dioxide and steam generated by natural gas combustion+unburned nitrogen+excess air. The calculation method for coal-fired boilers is similar. 3. How to calculate the flue gas flow rate of a rotary kiln with a diameter of 4.8 meters and a length of 74 meters
Calculation formula and parameter value method for the flue gas flow rate of a rotary kiln
1. Basic calculation formula: flue gas flow rate (Nm ³/h)=kiln cross-sectional area (m ²) × flue gas flow velocity (m/s) × 3600, where - cross-sectional area=π × (diameter/2) ²=3.14 × (4.8/2) ² ≈ 18.1m ² - flow velocity is usually taken as 1.5-3.5m/s (to be determined according to the process) 2 Key parameter description 2.1 Basis
1.5-2.5m/s - If it is a cement kiln, the industry standard for 2023 suggests taking 2.8m/s2. Temperature correction requires converting the operating flow rate to the standard state (0 ℃, 101.325kPa): actual flow rate=standard flow rate x (273+flue gas temperature)/2733 Calculation example based on a diameter collapse of 4.8m and a mass flow rate of 2.8m/s: 18.1m ² × 2.8m/s × 3600 ≈ 182448Nm ³/h. If the flue gas temperature is 200 ℃, the operating flow rate is 182448 × (273+200)/273 ≈ 316000m ³/h. 4. Precautions - The actual flow rate needs to consider the air leakage coefficient (usually 1.1-1.3) - The fuel type (coal/gas) will affect the volume of the flue gas composition - The latest GB 4915-2023 requires that the flow rate deviation at monitoring points should not exceed ± 5%
4. Calculation formula for flue gas flow rate when sampling with pitot tubes in thermal power plants
According to the Bernoulli equation: or Δ P=1/2 ρ VV Among them, Δ P is the pressure difference collected by the pitot tube, ρ is the smoke density, V is the smoke flow velocity, and the smoke flow velocity can be calculated using this formula. Flow velocity * cross-sectional area=flow rate. Besides, ρ=PM/nRT， The temperature and pressure of the flue gas are related, and the pressure should be basically atmospheric pressure. Temperature has a significant impact, so a temperature sensor is needed to measure the temperature and perform temperature compensation. If necessary, pressure compensation should also be done.
5. Calculation formula for flue gas flow rate when using pitot tube sampling in thermal power plants
When using pitot tube virtual a
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