Experimental Study And Simulation On Flue Gas Flow Straight Drying Of Biomass Particles

In China, characteristics of biomass resources is variety, wide distribution and large output. During the "13th Five-Year" period, to promote the efficient use of biomass energy is an important measure. Crop straw accounted for 47% of the total amount of biomass resources.Usually the biomass straw harvest time is relatively concentrated, which need to be stored for a long time. However, the humidity content of the new harvest straw is usually more than 50%. So the straw is very perishable,which greatly limits the use of crop straw. Because of the weather factors, the drying time is longer by the traditional drying method. With the high temperature flue gas generated by the internal combustion engine, this paper will introduce the pneumatic drying technology. While achieving the drying of biomass straw particles, it can also use the waste heat of flue gas to achieve a win-win situation.First of all, this paper focuses on the influence of flue gas temperature, flow rate, particle flow, particle initial moisture content and particle size of five single factors on drying process. According to the corn straw particles, a set of experimental system of flue gas waste heat recovery of natural gas generator was set up. The experiment was carried out under different conditions by controlling variables. The parameters such as the moisture content of the particles, the outlet temperature of the particles and the moisture content of the flue gas and the outlet temperature of the flue gas were measured. Based on this data, the total heat transfer, water evaporation, and the heat absorbed by the particles during the drying process were calculated. At the same time, the drying curve was drawn to reflect the drying pattern. The following conclusions are obtained:With the change of flue gas temperature, the moisture content of the particles is linearly changed; When the gas flow and particle flow rate change, there is the best gas solid ratio to make the maximum evaporation of water. And the relationship between the optimum gas and solid ratio is Gp=0.257Gg-0.002.The increase of the initial moisture content of the particles does not lead to a significant change in heat transfer and water evaporation; Small particle size can effectively increase the amount of water evaporation. This provides a strong support for the determination of the optimum drying conditions.In addition, through the analysis of heat and mass transfer in the drying process, the hypothesis is put forward.The mathematical model of drying of flue gas flow is established from the momentum equation, energy equation and mass equation. Then write the MATLAB program for its solution. The model was checked with the experimental data, which make the model closer to the actual situation. Model can be used to guide and optimize the design of the flue gas flow drying equipment.Finally, under the guidance of the mathematical model calculation results, dry tube length、diameter and the optimal feed parameter of 30kW natural gas generator flue gas waste heat recovery drying equipment is determined. Under the dry condition, the moisture content of biomass straw particles remained at about 20% after drying,which reached the long-term storage conditions. This paper has successfully solved the problem of biomass is not easy to dry.