Flow characteristics of three-phase foam in mine gob and its application

To study the flow characteristics of three-phase foam in gob area,different perfusion experiments in coal mine gob were designed and put forward in the paper.Through the observation of flow range,flow characteristics of three phase foam were analyzed with different flow rates.And,unsteady seepage process of three-phase foam was simulated with CFD software.Base on experiment and numerical simulation results,flow characteristics of three-phase foam and its major influence factors are discussed,and the optimal arrangement distribution of mine fire control drills is also determined.Research results show that the flow range and stacking height of three-phase foam in gob are significantly influenced by gravity.The vertical stacking height and horizontal diffusion distance of three-phase foam are also directly related to the flow volume of foam perfusion,the larger flow single hole perfusion volume,the higher stacking height and the longer diffusion distance could be obtained.

Tuning rheology and fire-fighting performance of protein-stabilized foam by actively switching the interfacial state of the liquid film

Biomolecular self-assembly has lately emerged as an intriguing method for creating stable gas-liquid dis-persions with unique functional characteristics.In this work,protein-metal coordination complexes were designed as the stabilizer for generating ultrastable fire-fighting foam and creating interfacial architec-tures that were actively switched between"rigid"and"mobile"interfacial states of liquid films in re-sponse to changes in pH and bulk solution compositions(metal ions or alkyl polyglycosides).The re-flected light interferometric technique was used to check interfacial states,and the foaming kinetics and rheological response of aqueous solution and liquid foam were investigated by dynamic surface tension tests and oscillatory rheology analysis.The results showed that liquid foams with mobile films with lower yield limits had a faster spreading rate to cover the burning oil,liquid foams with semi-rigid films can-not extinguish fires due to interfacial instability,and the enhanced rheology of the foam with rigid films established a robust and impenetrable barrier to effectively suppress fuel evaporation and combustion.A new correlation between interfacial properties and the fire-fighting performance of foam was proposed,which showed that the fire-extinguishing time of foam could be well correlated by the interfacial states or film lifetime rather than classical thermodynamics entry,spreading,and bridging coefficients(ESB co-efficients).

Practice of Fighting Fire and Suppressing Explosion for a Super-Large and Highly Gassy Mine

The Baijigou Mine fire in Ningxia Province,which broke out on October 24,2003,affected more than 108 m3 of the mine and was probably the largest underground fire in China in recent years. In addition to its size,the fire was also characterized by excessive air leakage and the potential for violent methane explosions. A series of new measures were taken to fight the fire,including sealing intake tunnels with water,injecting three-phase foam through boreholes,and flushing with a large volume of nitrogen. The fire was successfully extinguished and production re-sumed soon afterwards; not one single methane explosion occurred during fire-fighting and afterwards.

Prevention and control of coalfield fire technology:A case study in the Antaibao Open Pit Mine goaf burning area,China

It is very difficult to clearly detect the location of a burning area in a coal mine since it is hidden underground.So we conducted research on the distribution of the burning area before controlling it.Firstly,the original drilling technique was used to analyze and determine the loose and scope of caving of burning area through field test,and then obtained the gases and the temperature data in this area were according to the borehole data.By analyzing these data,we found out that the location of burning area concentrated in the loose and caving area;and finally,the location and development of the burning area within the tested area were accurately determined.Based on this theory,we used the ground penetrating radar(GPR) to find out the loose and caving scale in the burning area during the control process of the burning area,and then located the fire-extinguishing boreholes within target which we used to control burning fire in the section.A mobile comprehensive fire prevention and extinguishing system based on the three-phase foam fire prevention and control technique was then adopted and conducted in the burning area which took only 9 months to extinguish the 227,000 m 2 of burning area of 9# coal.This control technology and experience will provide a very important reference to the control of other coalfield fire and hillock fire in the future.