Design And Theoretical Study On Concentration Heating-type Gasification Boiler Of Biomass

Our country is facing a series of energy and environmental issues with energy shortages and environmental deterioration, in order to achieve our economic, social and environmental sustainable development, to find alternatives to fossil fuels has become very necessary. It is very rich in biomass resources in China, according to relevant statistics that China can produced about 700 million tons of agricultural waste each year, or about more than 300 million tons of standard coal.In China, many township enterprises and institutions are mainly in small-scale coal-fired boilers for heating. These boilers are basically out of the city and does not meet the national emission standards. There are even some classrooms, dormitories still use coal stoves for heating, so that not only increase security risks, but also increased the pressure on the environment. On the other hand, rich straw resources in rurals wasn't disposed to use but wasted on nothing, the same time causing environmental pollution. Therefore, based on the heating issue of township enterprises and institutions, this paper is to explore a way to rational use of biomass to address the central heating, mitigation of rural energy shortages problems.The paper is based on "2007 National Spark Program (2007EA105008)" research projects to design a biomass gasification combustion steam boiler in which we use the fuel pellet. Based on analysis and comparison of grate's various characteristics, we chose the level reciprocating grate as combustion equipment of boiler, and designed the overall layout of the boiler; Based on biomass fuel pellet combustion characteristics and thermal parameters, we designed in detail and calculated the form and volume of the boiler furnace, grate area, convection tube bundles, as well as the boiler auxiliaries; In accordance with GB/T16508-1996 "shell boiler pressure parts intensity calculation",we designed the boiler drum, tube plates, manhole and hand hole, and made stress analysis to manhole and pipe plate using ANSYS software, and the intensity evaluation is done with the application of the stress-linear principle from different paths in the stress concentration region of the components under stress to assure the safety of the boiler shell.The overall design idea is to increase the furnace height that can enhance gasification level of pellet fuel. By strengthening and controlling the supply of secondary air which increase disturbance effect on volatiles of the biomass and extending the volatile residence time in the furnace, to ensure that secondary air and gasification products are uniformly and adequately mixed gasification combustion intensified, got to the point of clean combustion and improving of the boiler's combustion efficiency, and finally the efficiency of the boiler.