Study on Methane Explosion Suppression in Diagonal Pipe Networks Using a Fine Water Mist Containing KCl and an Inert Gas.

To explore an effective approach for suppressing methane explosions in actual pipe networks, we used a custom-made diagonal pipe network experimental system to assess the suppression of methane explosions using a fine water mist containing KCl and an inert gas. The shock wave pressure, flame wave velocity, and flame wave temperature under different suppression conditions were compared to characterize the effects of explosion suppression under different working conditions, and the mechanism of explosion suppression was analyzed. The results showed that under single-factor explosion suppression conditions the optimal explosion suppression results were achieved when the volume fraction of N2 was 25%, the volume fraction of CO2 was 20%, and the concentration of KCl was 7%. The suppression effect of CO2 on the flame wave temperature was better than fine water mist containing KCl and N2, and the suppression effect of fine water mist containing KCl on the shock wave overpressure and flame wave velocity was more significant. Under the working conditions of fine water mist containing KCl, which was coupled with an inert gas to suppress the explosion, the suppression effect of the fine water mist containing KCl coupled with 20% CO2 on the shock wave overpressure, flame wave velocity, and flame wave temperature was considerably better than fine water mist containing KCl coupled with 25% N2.

Study on the Effect of KHCO3 Particle Size and Powder Spraying Pressure on the Methane Explosion Suppression Characteristics of Pipe Networks.

To achieve the best explosion suppression effect of an active powder spraying system, the KHCO3 powder suppression test for a 9.5% methane-air premixed methane explosion was studied based on an independent test platform consisting of a pipe network. The suppression effect of KHCO3 powder particle size and powder spraying pressure on the methane explosion shock wave pressure, flame wave velocity, and flame wave temperature were studied, and the explosion suppression mechanism was analyzed. The results indicated that both the particle size of the KHCO3 powder and powder spraying pressure had a significant effect on the explosion inhibition. When the spraying pressure was in the range of 0.1-0.2 MPa, the increase in KHCO3 powder spraying pressure on the effect of explosion suppression was significantly enhanced, and when the powder spraying pressure exceeded 0.2 MPa, the explosion suppression effect did not obviously increase. With a reduction in the KHCO3 powder particle size, the effect of explosion suppression significantly improved, and when the KHCO3 powder particle size was reduced to 50-75 µm, we observed the best shock wave pressure, flame wave velocity, and flame wave temperature suppression effect.

Study on emergency escape route planning under fire accidents in the Burtai coal mine.

Developing an effective safety emergency plan for coal mines is crucial to prevent and reduce accidents, as well as improve the emergency response capability. This paper identifies and analyzes potential accident hazards in the Burtai coal mine through a comprehensive and practical investigation of risk factors. Based on a mathematical model of a mine fire disaster relief algorithm, the MATLAB software is used to conduct numerical simulations of the dynamic spreading process of the fire smoke. Several escape routes are determined based on the simulation results, including the main escape route at the working face of coal mining, the main escape route at the working face of tunneling, and the main escape route against the reverse wind in the main inclined shaft, the auxiliary adit, and the main air intake roadway. The results presented in this study can provide guidance for improving fire emergency escape and rescue plans of the Burtai coal mine.

Sampling Investigation of the Situation of Rational Drug Use in China / 中国药房

OBJECTIVE: To survey the habits of public drug use in China and its reasons and to put forward countermeasures so as to provide reference for government and decision-making department. METHODS: From Nov. 2008 to Feb. 2009, questionnaire survey was adopted in 31 provincial administrative regions except for Hong Kong, Macao and Taiwan. 26 000 questionnaires were collected and 1 100 physicians were interviewed. SPSS17.0 software was used to analyze 11 796 valid questionnaires statistically. The frequency of words used by physicians was counted. RESULTS: The residents don’t have enough knowledge to support them to use medicine rationally. And they are not compliant with prescription but take medicine by arbitrariness. 44.88% of residents don’t buy medicines according to prescriptions and 74.39% don’t take medicine following treatment course, stop taking medicine once symptom relieve or change the category of drugs frequently. CONCLUSION: The improvement of pharmaceutical market environment, enhancement of medication guide and popularization of medication knowledge can promote rational use of drug.