Study On Optirnization Method Of Drill Pipe In Coal Mine Based On Improved Multi-objective Particle Swarm Algorithm

Coal and gas outburst in soft outburst coal seam has always been a major problem threatening the coal mine safety production.At present,using the rib drill pipe to drill a holes in specific areas of coal wall for draining gas is a commonly method to solve the problem of gas outburst.However,coal blocking often leads to sticking drilling in the process of drilling,resulting in low hole formation rate,low drilling efficiency,restricted hole formation depth and other problems,which seriously affect the efficiency of gas treatment.In order to solve the above problems,this paper studies optimization method of drill pipe in coal mine based on improved multi-objective particle swarm optimization.Aiming at the complex working conditions of drilling in soft and outburst coal seam,the physical factors,geological factors and mechanical factors of sticking are analyzed.The factors that can be optimized to cause sticking are deduced,including the structure of rib drill pipe and drilling rate of rib drill pipe.Based on working conditions of drilling in soft and outburst coal seam,The mechanism of mechanical slag discharge of rib drill pipe is analyzed.According to the formula of the quantity of mechanical slag discharge per unit time pipe and the transport energy of rib drill pipe,The objective function is established.The structural parameters of rib drill pipe are optimized by the multi-objective and improved particle swarm algorithm.EDEM is used to simulate slag discharge process of the optimized drilling pipe.The simulation results show that the transport energy of rib drill pipe not only can be reduced,but also the amount of slag discharge per unit time of rib drill pipe is increased.The theory of computational fluid dynamics is used,the mechanism of fluid discharge from rib drill pipe is analyzed,and the mathematical model of critical velocity of pulverized coal is established.The optimal critical wind velocity was determined by experiments.The theory of gas-solid two-phase flow is used,the air supply pressure required by rib drill pipe pulverizing process is established and analyzed,and the air supply pressure is equal to pressure loss of rib drill pipe pulverizing process.Based on the force condition of the coal in slag discharge process,The motion model of a group of coal particles is established.The formula of the quantity of slag discharge per unit time pipe under the ideal state is deduced,and the mathematical model of the quantity of the coal produced per unit time is established.According to the numerical relationship between the quantity of slag discharge and the quantity of the coal produced per unit time during the normal drilling of the rid drill pipe,the ideal drilling velocity of rib drill pipe is obtained.According to the actual working conditions of drilling,a simulation platform for rib drill pipe of slag discharge process is designed and built.The ideal drilling velocity is tested and amended by the experiment.The optimal drilling velocity is obtained,which can guarantee the highest drilling efficiency and effectively avoid the slag blocking.Based on the optimization results of mechanical and fluid slag discharge of rib drill pipe,A new rib drill pipe was designed and machined.The rib drill pipe is used to carry out drilling experiment to release in Xiangshan coal mine of ShanXi province.Compared with the original drill pipe drilling effect,the average of the quantity of slag discharge per unit time of the new rib drill pipe increased by 31.5%,the probability of pore formation increased by 19.4%,and the average drilling depth per pore increased by 39.8m.The optimization scheme proposed in this paper improves drilling efficiency and greatly reduces the possibility of sticking due to coal blocking.