Musical Ceramic mugs melody mug cup Coal combustion process is what?

Musical Ceramic mugs melody mug cup

The combustion of coal can be broadly divided into three stages.

The first stage is on fire stage. The coal is added to the fire box, the heat; coal surface free water is discharged to above 100 . Discharge of volatile above 200  ,300-400  volatile discharge the most dramatic. Affect the ignition phase of the speed of the main factors is the temperature, and air contact area is too small fire box temperature is too low, or too wet coal, or coal seam is too thick, will extend the fire stage. Conversely, the ignition stage can end in a shorter time. In this stage, the coal can only absorb heat from the fire box, but can not emit heat, and therefore, it is desirable to fire stage sooner the better.

Second stage of the combustion stage. This phase includes the combustion of fixed carbon and volatile and volatile continue to discharge. Fixed carbon combustion, volatile start burning 600-650  400-450 . The combustion of fixed carbon is divided into three steps: First, of oxygen through a layer of soot around the gas diffusion, in contact with the carbon particle surface; followed by chemical reaction of CO and CO2 of oxygen and carbon; finally generated gas proliferation, leaving the carbon particle surface. Therefore, this stage of the combustion speed is limited by the constraints of the diffusion speed and the chemical reaction rate of both. Below 700 , fixed carbon with oxygen to generate slow chemical reaction rate of CO and CO2, to speed up the chemical reaction, which is to speed up the burning rate, the only effective way is to raise the temperature. Therefore, in the stage 7oo ° C or less, the temperature is a major factor in controlling the combustion process. Above 700 , fixed carbon with oxygen to generate the chemical reaction rate of the CO and CO2 is very fast, but relatively slow down the diffusion rate of the gas. The reason is the higher the temperature, the faster chemical reactions; but the increase in the viscosity of the gas film, film thickening, and thus slow down the diffusion rate. At this stage, to further accelerate the combustion, the most effective approach is to increase the air velocity, film thinning of the carbon particles around the gas, thereby increasing the diffusion rate. Therefore, the high temperature phase above 700 , the flow rate of the gas is the main factor controlling the combustion process, some coal burning tunnel kiln to take large pumping force operation theoretical basis here.

The third stage is the burnout stage. Since the combustion stage has elapsed, most of the heat has been released, the temperature decreases gradually. The coal ash layer on the surface, and, with time, the ash layer is continuously thickened, wrapped in residual fixed carbon of the coal central slow combustion, until the coal completely burn.