Modeling And Control Of Municipal Solid Waste Incineration Process In Large Scale Mechanical Grate-fired Boiler

In accordance with the demands of rapid urbanization, using MSW (Municipal Solid Waste) incineration power plant to process MSW has risen gradually. There are two main attributes of MSW in China:high water content and low heating value. They are quite different from developed countries, so the automatic combustion control technology can not running as it is in developed country. Learn more about the MSW features in furnace is quite important to eatablish a proper automatic combustion control strategy in our country.The key of MSW incineration control is the refuse, which is the root of difficult to control. First of all, the refuse components and the distribution attribute are analyzed. MSW is classified again by low heating value, the probability density functions are calculated in the area which the refuse were sampled. After the liner correlation analysis of MSW water content, kitchen waste is the most influential factor of water content. On the basis of analysis, refuse module is established which components parameter could be adjusted.Then, the drying process of refuse module in MSW incinerator is analyzed including heat convection and radiation transfer process. Depending on the water mass variation, the burning up interface concept is put forward. With the sampled historical data, software measuring of burning up interface is carried out. Burning up interface is a boundary of dynamic drying area which is usually considered as a static drying area. The burning up interface step response of water content, primary air, drying grate speed and primary combustion chamber temperature are also presented. The fluctuation of burning up interface shows that the drying area on the grate is in continuously moving process. Water content, drying grate speed and primary combustion chamber temperature have great influnce on burning up interface, and the temperature and pressure of primary air have limited influence. The calculated results agree well with the actual incineration process. With the help of burning up interface, the combustion temperature could be explained up to some extent.In accordance with the ratio of primary air mass to the dissolved volatile mass, three type of volatile combustion mode are put forward, including reaction limited mode, insufficient combustion mode and sufficient combustion mode. Three chemical reaction equations are described, which are also mass balance equations. Through the numerical experiment, the mass distribution pattern of reactant and product along the grate are obtained. The results show that sufficient airflow could avoid the refuse layer to work in the reaction limited mode. The grate speed should be carefully adjusted to maintain stable combustion.Modeling and simulation in the municipal solid waste incineration process are realized using Flash technology. This is a new method for the modeling and simulation. The simulation of combustion effect is introduced, like refuse layer pile up and unburned refuse layer.At last, control strategy for the grate-fired furnace is introduced. The automatic combustion control strategy with the burning up interface correction is put forward. A sequence control system for boiler starts up and shutts down has been successfully applied in the MSW power plant.