How is thermal buoyancy on a coke oven generally calculated?

Thermal buoyancy is the upward force resulting from the decrease in density of a gas as its temperature rises, allowing it to rise above the cooler surrounding air. The calculation of thermal buoyancy is usually based on Archimedes’ principle, which states that the buoyant force acting on an object in a fluid is equal to the weight of the fluid it displaces. For gases, this principle can be expressed as thermal buoyancy equal to the weight of cold air per unit volume minus the weight of hot gas of the same volume. Thermal buoyancy F can be estimated using the following formula: \ Where: – \( F \) is the buoyant force (newtons, N) – \( g \) is the acceleration due to gravity (9.81 m/s²) – \( V \) is the volume of the gas (cubic meters, m³) – \( \rho_{cold} \) is the density of the cold air (kilograms per cubic meter, kg/m³) – \( \rho_{hot} \) is the density of the hot gas (kilograms per cubic meter, kg/m³). The density of the hot gas can be calculated using the ideal gas law \( \rho = \frac{P}{R \cdot T} \), where \( P \) is the pressure, \( R \) is the specific gas constant, and \( T \) is the absolute temperature. For different coke oven areas, you need to know the initial and final temperatures of the gas, its volume, as well as whether there are any pressure changes in the area in question. If pressure changes are ignored, thermal buoyancy can be estimated based solely on the temperature difference. For example, the thermal buoyancy in each area – from the small flue to the roof storage area, from there to the bottom of the vertical flue, and then to the observation hole – can be calculated using the aforementioned method. In practical operation, various factors may also need to be considered, such as the composition of the flue gas and the operating condition of the coke oven. More accurate calculations may require the use of specialized fluid dynamics software for simulation. .