Research On Explosion-proof Technology Of A Mine Diesel Engine Intake And Exhaust System

Explosion-proof diesel engine as the main power of rubber wheel vehicles is widely applied to the coal mine since it has many advantages,such as high efficiency,safety,wide applicability,flexibility,multi-purpose.Explosion proof diesel rubber wheel vehicles often work in the coal environment,which is exposed to methane gas and dust.Modifications with explosion-proof measurement on the diesel engine must be made to ensure safety.The explosion-proof modifications on diesel engine must meet the MT990-2006 regulation,which declares that the surface temperature of components on explosion-proof diesel engine must be below 150℃,and the exhaust outlet temperature must be below 70℃.A 240 kw explosion-proof diesel engine of 40 Y explosion proof diesel trackless rubber wheel vehicle is studied.The original explosion-proof diesel engine is equipped with explosion-proof intake grille device,exhaust manifold with water jacket,turbine with a water jacket and an exhaust gas treatment water box.High fuel consumption,high emission,high noise,high maintenance costs and low attendance are the typical four problems of the vehicle,which are caused by the original explosion-proof structure according to the data acquisition from the vehicle.The original explosion-proof structure increases the inlet and exhaust system resistance.Moreover,the water jacket reduced exhaust energy for turbine working.As a result,the pump work is increased and the intake flow mass is reduced.Consequently,the power output performance,fuel economy and emissions of engine are significantly worsen.This paper designed intake and exhaust explosion-proof system of explosion proof diesel engine based on the understanding of explosion proof technology and explosion proof diesel engine regulations.Automatic explosion-proof parallel intake system,double structure with air interval type and high temperature exhaust gas spray cooling system are specially adopted.Automatic explosion-proof parallel intake system switches from normal working mode to explosion-proof working mode when the flame spread outward through air intake system,which reduces the flow resistance caused by the intake grille.Using the double structure with air interval type,the turbine power energy is increased with external surface temperature below 150℃.A new spray cooling system is adopted to reduce exhaust temperature in this research,which includes water cooling,heat exchange and spray cooling.As a result,the problem of resistance increase caused by exhaust gas treatment water box is effectively improved.The factors affecting the spray cooling of the high temperature exhaust gas including nozzle installation position,nozzle diameter,spray pressure,injection mode,droplet diameter,pipe wall temperature,exhaust temperature and exhaust flow mass were experimentally analyzed further.And the pressure and velocity field inside exhaust grille was obtained by a CFD simulation of exhaust grille for analyzing the cause of resistance increase.It provides a theoretical basis for the design of new intake and exhaust system of explosion-proof diesel engine.Finally,the combustion process is promoted due to the increase of engine intake flow mass and reduction of exhaust back pressure.The power output,fuel economy and emissions of engine are significantly improved,which effectively reduces the hazardous effects of polluted gas on mine staff.