Influence of change of flue gas properties on bag dust collector

Influence of change of flue gas properties on bag dust collector

Compared with normal temperature flue gas, the characteristics of high temperature flue gas are very clear, which is mainly manifested in the volume, density and viscosity of flue gas, and the difference of dew point and explosion limit of flue gas. The change of flue gas properties of bag dust collector is mainly manifested in the following aspects. The volume, the number of molecules per unit volume of a given mass of gas, is constant. The rate at which molecular motion intensifies as the flue gas temperature rises. From the gas equation of state we know that if we keep the gas pressure constant, the volume of the gas will be. That is, the volume flow of flue gas under working condition changes with the change surface of flue gas temperature. The volume flow of flue gas under the working condition with the rise of temperature is much larger than the volume flow of flue gas under the standard condition, so the design and calculation of equipment and pipeline should be based on the volume flow of flue gas under the working condition. Density, viscosity, dew point. The density viscosity and dew point of the smoke are described in the chapter. Density: If the pressure of the gas is constant, then the density of the gas is inversely proportional to the change in temperature. High temperature flue gas is usually composed of a variety of gases, its composition, pressure and temperature changes, will cause changes in the density of flue gas, design selection should be considered according to the mixture of gases. Viscosity is increased with the increase of flue gas temperature.

Special attention should be paid to whether there is acid gas in high temperature flue gas, and the explosive limit of acid dew point should be avoided when designing. The high temperature flue gas produced by electric steel furnace smelting contains combustible components such as carbon monoxide and hydrogen. When these combustible components mix with air or oxygen and reach the level of ignition, there is a risk of explosion. Classification of Explosive Limit and Ignition Temperature methods Before the high temperature flue gas enters the bag dust collector equipment, due to the limitations of the material and structural conditions of the equipment, the high temperature flue gas should be cooled. Cooling method, according to the different medium, can be divided into water cooling and wind (air) cooling two. According to the different heat transfer mode between the medium, and can be divided into direct and indirect two categories. Direct use of water or air directly mixed with high temperature flue gas, to achieve the purpose of cooling. Direct methods can be divided into direct water cooling and air mixing. Direct water cooling. Spray method is used to spray the water mist directly into the high temperature flue gas, so that it can directly exchange heat with the high temperature flue gas. The latent heat of vaporization of water is used to reduce the high temperature flue gas to the required temperature. According to the different ways of dust removal and purification and apparatus, it can be generally divided into two kinds: saturation and evaporation. Saturation: By spraying a large amount of water to the high temperature flue gas, so that the high temperature flue gas in an instant to the corresponding saturation temperature, the method is called saturation.

According to the change of flue gas temperature, when the right amount of water spraying to high temperature flue gas, the spray into the water droplets fully atomized, atomized water droplets particle size is finer, the better the water mist particles in contact with high temperature flue gas in a very short time, the absorption of flue gas is hot, all vaporized, and the flue gas reheating to form a kind of unsaturated gas, its relative humidity is generally about 10-20. This method of spraying is called evaporation. Air mixing, a certain amount of normal air is directly mixed into high temperature flue gas through air mixing valve, so that the population flue gas temperature of bag dust collector equipment can meet the temperature requirements of the equipment, this method is called air mixing. The usual practice is to set up a mixed air valve or air dilution valve before the inlet of the precipitator. Indirect use of water or air and high temperature flue gas in the heat exchanger tube or heat exchanger inside and outside, to achieve the purpose of cooling. Indirect methods can be divided into indirect water cooling and indirect air cooling.