Lv Junfu

Air flow simulation in high-pressure air blower with splitter blade

In the process of air blower design, splitter blades could be adopted in the middle of rotator to improve the air blower performance. In order to understand the flow pattern in the high-pressure centrifugal blower of 9–26 type with splitter blade thoroughly, the three dimensional air flows in the air blower is numerically simulated and analyzed with computational fluid dynamics. Standard k-ε turbulence model and unstructured grids are applied in computation. The calculating results showed that for the same condition, the flux of the air blower was improved more than 5% and the total pressure at outlet of the air blower was improved more than 10% due to the splitter blade. It is found that the length of the splitter blade affected the flow rate either and there is an optimum length. Compared with the air blower without the splitter blade, the velocity and the pressure distribution in the air blower impeller channel are quite different after installing the splitter blade. When installing the splitter blades, its structure should be carefully considered.

Investigation of Coal Reactivity Effects on a 1000-MW Tangential Coal-Firing Boiler

The parameters in char combustion are important for boiler simulation. This study investigates the effect of coal activation energy on the simulation of coal combustion. A diffusion-kinetic (DK) char combustion model was firstly used to identify the activation energy in sensitive range that strongly affects the char combustion rate. It is found that the sensitive range depends on particle temperature, particle diameter, and oxygen fraction. A 1000-MW tangential coal-firing boiler was simulated in the article to evaluate the effects of activation energy. Numerical results show that char burnout rate decreases with higher activation energy. Average scalars such as temperature and oxygen fraction change slowly with the activation energy when it is less than the middle value of the sensitive range. However, when the activation energy is higher than the value, the burnout rate drops dramatically, the high-temperature zone moves upward to the area between burner nozzles and OFA nozzles. Average temperature, reaction rate decrease, and O2 mass fraction increase in the burner zone.