| With the extensive use of energy sources like coal,petroleum and etc.,the remaining storage capacity of non-renewable energy on the earth is gradually dried up.Therefore,many scholars at home and abroad have begun to pay attention to the research of biomass energy such as cellulose fuel.Straw-based cellulose fuel has abundant research,low prices and immeasurable prospects for use.However,the complex internal structure of straw-based cellulose raw materials will seriously hinder the accessibility of enzymes to cellulose.Therefore,it is necessary to conduct reasonable pretreatment operations on the raw materials before enzymatic hydrolysis or fermentation.The results of the survey conducted by many scholars and experts have found that steam explosion technology which has the advantages of higher cellulose conversion rate and less pollution is an effective method for pretreatment of cellulose.At present,the steam explosion equipment developed by many scholars and experts has two types: batch type and continuous type.Intermittent steam explosion equipment has disadvantages such as discontinuous production,low production efficiency,and difficulty in industrialization.Compared with the batch type,continuous steam explosion equipment has larger processing capacity and higher efficiency,and is suitable for large-scale industrial production.However,the continuous type equipment is expensive.The steam in the traditional continuous steam explosion equipment cannot be recycled and then result in higher production costs.Meanwhlie,the discharged steam is mixed with tiny materials,which are scattered in the air and will cause environmental pollution and waste of materials.Therefore,this thesis the kenaf straw as the research object,design a constant steam explosion machine with tail gas recovery,which can realize the recycling of steam,reduce raw material loss,and automate continuous industrial production.The thesis consulted a lot of literature about steam explosion pretreatment equipment,and determined that the equipment is composed of driving mechanism,feeding mechanism,screw conveying mechanism,discharging mechanism and steam supplement device.For the extrusion screw of straw cellulose fuel pretreatment equipment,the spiral blade is prone to breaking down under the action of high temperature thermal stress.The paper used software ANSYS to analyze the stress condition of the blade by using temperature,total heat flux,equivalent elastic strain,and equivalent stress as the measurement standard.In order to optimize the structure,the paper changed the parameters of the spiral blade and compared the different analysis results of them.While using the software Fluent to perform flow field simulation on the steam return air pipeline,analyze the changes in the temperature field,velocity field and pressure field of the steam in the pipeline,and formulate daily inspection and maintenance programs based on the analysis. |
