Concentration Distributing And Explosion Hazards Study Of Diesel Oil Vapor In Marine Engine Room

Diesel oil is widely used as marine fuel. In its use process, the fuel sometimes leaks out and vaporizes into the air, becoming a combustible vapor-air mixture in the engine room. And the mixture will explode once it meets fire spark. To prevent such accidents, the detection and alarm system for combustible gas is successfully used in most ships. However, there are still two problems with the system.(1) The structure of engine room is quite different. And the fuel leaks in different ways. So, the diesel vapor concentration distributing is different in different areas. In this case, we do not know where to install the concentration sensor (main component of the detection and alarm system, to detect the vapor concentration).(2) Marine diesel oil is composed of hydrocarbons from C12 to C23. At present, the explosion range of diesel oil is lack of research. And there is no credible experiment data about it. So people do not kown exactly whether the alarm concentration is safe or not. If it is lower than the exact data, the concentration sensor will keep in alarm state, so that the alarm system will misinform a lot. While if it is higher than the exact data, the alarm system will fail to function when there is a danger.To solve the above-mentioned two problems, this article researched from two aspects.(1) Simulated the concentration distributing of diesel oil vapor by numerical simulation According to Molecule Diffusion and Mass Transfer theories, and combining withGradient Transport theory, we founded a mathematical model of diesel oil evaporation and programed a piece of software of diesel oil vapor concentration distributing. Using the program we can simulate the concentration distributing of diesel oil. From the simulation results, we find that there is a thick oil vapor layer nearby the underground, and the underground concentration is largest.(2) Measured explosion limits of diesel oil by experimentThe volatility of diesel oil is very low under normal temperature. The explosion limits of diesel oil can not be measured out by general method. By establishing a set of new experimental facilities, we measured the explosion limits, especially low explosion limit (LEL) of two kinds of marine diesel oil (Military -35# and -10# Diesel oil) with "Temperature method" and "Weighing method". From the experiment result, we find that the LEL of -35#...