Research On Thermal Characteristics Of Hydraulic System In Cutting Section Of Shearer In Extremely Thin Seam

Our country’s thin coal seam resource is abundant,and mining becomes inevitable trend with the thick coal seam resource decreasing.But the input-output ratio of thin coal seam is low,and the economic benefit is not as good as that of medium thick coal seam,so some coal mines give up the exploitation of thin coal seam.With the mining requirements of the government in recent years,coal seams above 0.8m must be mined,and mining below 0.8m is encouraged.The mining problem of thin coal seams has gradually been paid attention to.In the mining process of extremely thin coal seam below 0.8m,due to the small mining space,poor geological conditions,the original equipment is difficult to mining,so it is urgent to study a new type of extremely thin coal seam mining machine.The new shearer of extremely thin coal seam is driven by hydraulic pressure.In the coal cutting work,because the heat dissipation performance of the closed system is not as good as that of the open system,the hydraulic system has a serious problem of temperature rise in the case of heavy load and continuous work.The temperature of the system will have a serious impact on the working performance of the shearer.This thesis takes the hydraulic system of the new extremely thin coal shearer as the research object,and carries out the work from the key parameter calculation of the hydraulic system,the modeling of the key hydraulic circuit,and the simulation analysis of the thermal characteristics of the hydraulic system,etc.The specific research content is as follows:Based on the design of the hydraulic system of the continuous shearer in extremely thin coal seam,the selection and calculation of the main components of the hydraulic system are carried out.On this basis,the heat balance mechanism model of the hydraulic system and the mathematical model of the pressure loss of the long distance pipeline are established,which provides a theoretical basis for the analysis of the thermal characteristics of the shearer.Based on the theoretical analysis of the thermal characteristics of each part of the hydraulic components in the hydraulic system,the simulation model of the thermal characteristics of the shearer hydraulic system in extremely thin seam is established based on the AMESim simulation software platform.At the same time,based on the heat balance mechanism,the theoretical calculation of the system heat production and heat dissipation under the cutting condition is carried out to verify the correctness of the simulation model.Based on the hydraulic system simulation model of shearer in extremely thin coal seam,combined with the heat exchange characteristics between pipe and pipe wall,the hydraulic system pipeline pressure loss model is obtained.The influence of heat exchanger,load,and flushing valve flow on the heat balance temperature of the system is studied,and the influence of system temperature on the response of system components is studied.The thermal balance characteristics of hydraulic system of continuous shearer in extremely thin coal seam are obtained.Aiming at the factors affecting heat exchanger heat dissipation power,the simulation model of plate heat exchanger was established by Fluent,and the appropriate range of initial temperature and flow velocity of cooling water was obtained.According to the design scheme of the hydraulic system of shearer in extremely thin coal seam,the prototype test platform is built,the thermal characteristics of the hydraulic system designed by the subject are studied,and the test results are analyzed.This thesis has 67 figures,22 tables and 91 references.