Research On Self-suction Foam Generator For Mine Ignition Source Prevention And Control

Thermal power disasters are the main body of major accidents in coal mine.The effective control of concealed ignition source in the early stage is the key of mine thermal power disaster prevention.Water-based foam has wide coverage,strong accumulation and low water consumption,so it has been applied effectively in mine fire prevention in recent years.However,due to the complex underground concealment space and harsh production conditions,the complex air supply system,poor portability and insufficient safety of traditional compressed air foam generator greatly limit the effectiveness of the foam fire prevention technology on the prevention and control of thermal power disaster ignition source.In order to solve the above problems,this thesis puts forward the research on the subject of new self-suction foam generator by using a comprehensive research method combining theoretical analysis,numerical simulation and experimental research,the main results and conclusions can be obtained and summarized as follows:A new self-suction foam generator is designed.Based on the principle of jet pump jet suction and existing foam generator,a new type of self-suction foam generator is proposed.It realizes the use of pressure water as the only power source,and uses the negative pressure effect formed by the high-speed water jet to suck the air around the device to complete the gas-liquid mixing foam.This design idea not only discards the external air supply system required by the traditional compressed air foam process,greatly simplifies the compressed air foam system and facilitates mobile fire extinguishing,but also enhances the safety of the whole system.Which improves on-site applicability of the new self-suction foam generator.The optimization of the structural parameters of the new self-suction foam generator was realized by adopting ANSYS Fluent.Based on the guiding principle of control variable method,the internal flow field of different structural parameter calculation models is numerically simulated and analyzed by using CFD numerical simulation software ANSYS Fluent.The influences of different structural parameters(diameter of nozzle outlet,diameter of suction hole,number of suction hole and Angle of suction hole)on the air suction properties and gas-liquid mixing effect of the new self-suction foam generator were described.Considering the suction volume,suction efficiency and gas-liquid mixing effect of the device,the optimal structural parameters of the new self-suction foam generator are:the nozzle outlet diameter is 5mm,the suction hole diameter is 15mm,the number of suction holes is 2 and the suction hole angle is 45 degrees.The air self-suction characteristics and foaming performance of a new self-suction foam generator were studied experimentally.Based on the numerical simulation results by ANSYS Fluent,this thesis designs the air self-suction characteristics experiment of self-suctioning foam generator,researching different structural parameters and working conditions on the performance of air self-suction characteristics to further determine the optimal structural parameters of the device.The study shows that when the device adopts 5mm nozzle outlet diameter,15mm suction hole diameter and double 45 degrees suction holes,the air self-suction performance of the device is the best.When the working pressure is 0.6MPa,the gas-water ratio of the device reaches the maximum16.6,and the inspiratory capacity is 35.4m~3/h.Finally,based on the air self-suction characteristics experiment of the device,the foam formation experiment was constructed to explore the influence of working conditions and suction parameters on the foam formation performance of the device.The research shows that the foaming ratio of the device the foaming ratio of the device presents a piecewise characteristic of"rapid increase-fluctuation rise"with the increase of working pressure,working flow and suction volume,and the device has realized the self-suction foaming under low pressure water conditions.The present dissertation has 67 figures,12 tables and 70 references...