Design And Research Of Small Biomass Shaped Fuel Burner

Since the 21st century,the pressure of environmental protection and the sustainable development of society have become urgent problems for our country.The effective use of resources has played a vital role in the sustainable development of our economy.Since the energy crisis,scholars from all walks of life have agreed that fossil fuels are about to be exhausted.Biomass energy is the fourth largest energy source.The use of biomass molding fuel can effectively adjust China’s energy structure,promote the efficient use of energy,and mitigate the greenhouse effect.In most areas of China,indoor heating is required in winter.Most of the heating energy is non-renewable energy such as coal and natural gas.However,China has abundant renewable biomass resources.Effective use of biomass energy can greatly ease the energy shortage.A household biomass shaped fuel burner with a power of 5kW and automatic feed was designed1)Analysis of combustion characteristics of biomass particulate fuel.Firstly,a brief overview of the combustion theory and combustion characteristics of in-situ biomass fuel and biomass shaped pellet fuel;Secondly,the combustion characteristics of three kinds of particulate fuels,such as rice straw,corn stalks and cotton stalks,were studied and analyzed,which provided a scientific basis for the development of a special burner for biomass particulate fuels for heating2)Structural design of biomass shaped fuel burner.The fuel feed amount is determined by the low-level heat generation of the fuel and the design of the fuel utilization rate;In order to solve the overfeed and underfeed of the fuel,a roller feeding device is used;To ensure the safety of the burner during operation and the cleanliness of the burner,the air extraction device provides power for the air to enter the burner;The furnace is composed of the furnace wall and the combustion box,and adopts the three-inlet method to increase the disturbance of the airflow in the furnace and improve the fuel combustion efficiency.The air inlet is at the bottom and sides of the combustion box.The working state of the burner can be affected by changing the area ratio of the air inlet and the shape of the combustion box3)Numerical simulation.By changing the area ratio of the air inlet and the shape of the combustion box,the gas disturbance in the furnace is adjusted to affect the working state of the burner.A 3D model of the air flow in the burner furnace with different combustion box specifications was established,and the CFD software Fluent was used to simulate the flow field distribution of the biomass burner under different structures.The simulation results show that when the area ratio of the air inlet is 0.7:0.2:0.1 with the funnel-shaped combustion box,the furnace airflow distribution is concentrated and the temperature reaches the highest,at this time,the fuel combustion is more sufficient.4)The prototype was assembled,the specification of the combustion box was changed,the multi-mode test was carried out,the combustion state was observed,the changes of the furnace temperature under each structure were collected,and the comparison with the simulation results showed that the error between the test value and the simulation value of the furnace temperature was less than 10%,which met the actual engineering requirement,proving that the working condition 3 was the best working condition and determining the structure of the combustion box.Under this condition,the performance of the burner was measured,the combustion efficiency of the three biomass particulate fuels was greater than 95%,and the fuel utilization rate was more than 85%.By extending the length of the exhaust pipe,the exhaust heat loss was effectively reduced.When the length of the exhaust pipe is more than 6m,the fuel utilization rate can reach more than 90%,which meets the requirements of efficient fuel utilization.