Experimental research on rapid removing characteristics of carbon monoxide generated during gas explosions.

A large amount of gas, such as CO, accumulates in a coal mine after an explosion, leading to CO poisoning. In this study, a self-developed platform was used to eliminate CO from coal mines and determine the mass of the rapidly eliminated CO and its concentration in the eliminated gases. Equations were derived to calculate the amount of CO eliminated and the removing rate. The results showed that a rapid removing reagent in the form of nonprecious metal catalysts is useful for removing CO. Removing agents with larger masses facilitated the activation, irrespective of the CO concentration. For removing reagent amounts of 10, 15, 20, 25, and 30 g, the amount of CO eliminated, the removing rate, and the time required to complete catalytic oxidation increased sequentially. The CO removing process could be divided into three stages (I, II, and III) based on the variations in the CO, CO2, and O2 concentrations during CO removing. The removing reagent first chemically adsorbs CO and O2, and then desorbs CO2. The final CO concentration tends to 0, the O2 concentration remains stable, and the CO2 concentration decreases. This shows that the ablation agent has an impact on the changes in the CO and CO2 concentrations.

Simulation of emergency evacuation from construction site of prefabricated buildings.

To ensure the safe construction of prefabricated buildings and improve the efficiency of the safe evacuation of construction personnel after a fire caused by improper operation during construction, this study used the PyroSim software to numerically simulate a fire situation based on the size and volume of a prefabricated building construction site. The variation rules of smoke visibility, CO concentration, and ambient temperature in the construction site of prefabricated buildings were analyzed and the available safe evacuation time was determined. Moreover, the Pathfinder software was used for simulation in combination with the physical attributes of personnel, evacuation speed, and personnel proportions. The time required for safe evacuation was determined and the factors influencing the evacuation time, such as the quantity and location of stacked prefabricated components, machinery, and appliances, and the number of on-site construction personnel, were analyzed. The data collected by the temperature sensor, CO concentration sensor, and visibility sensor reveal that the visibility and crash time are the key factors restricting the efficiency of personnel avoidance and evacuation. At 400 s, the visibility at the escape exit of the prefabricated apartment construction site was lower than 5 m. The crashing time of the building was 360 s, which is the critical point for casualties. The first emergency evacuation simulation took 398.7 s. The required safe evacuation time (TREST) > available safe evacuation time (TASET), and the original site layout cannot facilitate the safe evacuation of all construction workers. The evacuation time can be effectively reduced by re-planning the stacking positions of prefabricated construction site components, construction equipment, and other items, and reducing the number of personnel in the construction plane. The results of the second simulation reveal that the safe evacuation time (TREST) is 355.2 s. Because it is required that the safety evacuation time (TREST) < available safe evacuation time (TASET), the results are in line with the emergency evacuation requirements. The findings of this study can provide a theoretical basis for the rational planning of evacuation passages at the construction sites of prefabricated buildings and assist the management of construction site safety.

Removal of CO Generated by a Gas Explosion Using a Cu-Mn Elimination Agent.

Addressing the issue of suffocation and casualties caused by a large amount of poisonous CO gas generated after a gas explosion, research involving an experimental system for the removal of CO using a Cu-Mn elimination agent was studied. The influence of O2 concentration, temperature, and CO concentration on the elimination performance of the agent after a gas explosion was studied. The quantitative relationship between the amount of CO eliminated, the elimination rate, the O2 concentration, and temperature was analyzed. Further analysis was completed regarding the influence of O2 concentration, temperature, and CO concentration on the thermal effect in the elimination process. The results showed that the elimination agent had a rapid effect on the removal of CO. When the ratio of CO concentration to O2 concentration was closer to the stoichiometric ratio, the elimination and reaction were more complete, the time to complete elimination was shorter, and the peak temperature was higher. As the temperature increased, the time to reach the elimination limit became longer, the elimination rate decreased, the reaction was slower, and the peak temperature was lower. As the CO concentration increased, it was observed that the higher the peak temperature, the longer it took to reach the peak time. The results of the study provide a theoretical support for the catalytic oxidation of CO using the Cu-Mn eliminator after a coal mine gas explosion.