Numerical Simulation Of Marine Supercharged Boiler Combustion

Having advantages of small volume, light weight and strong power, marine supercharged boilers are chiefly equipped in marine power plant. To achieve these advantages is to pressurize the combustion chamber of the boiler. In this case the volume of chamber can be reduced, the mass flow rate of fuel gas speeded, and the area weighted heat flux enhanced on all heat exchanging surface eventually. In this paper, detailed analysis of combusting which is significant for boiler running have been carried out by means of numerical simulation.While combusting should be a complicated process, but the means of numerical simulation can lower cost of design manufacturing, improve efficiency of experiment work, reduce the mistake of design with fewer repeated work. Supercharged boiler combustion simulation making use of numerical simulation and analysis of aerodynamic characteristic inside furnace introduces a lot of work to do. In this paper the simulation platform is FLUENT 6.2.16—a successful commercial fluid mechanics software. The geometric dimension ratio of modeling furnace to real furnace is 1:1.For the sake of the accuracy of simulations and to get real furnace aerodynamic characteristics, there are five rows of tubes downstream the furnace outflow. Marine supercharged boilers take heavy oil as fuel. While spraying into furnace to mix with combustion supporting air, heavy oil has been atomizing into fine droplets before combustion. Atomizing, heating, vaporizing, boiling of fuel oil appears as discrete phase model, while standard k-εmodel would be used for turbulence modeling, and the equilibrium chemistry model for combustion chemistry. In this paper, aerodynamic characteristics and temperature distributions inside the furnace was elaborated. Distributions of heat flux of water cooled wall and convective tubes determined by furnace aerodynamic property which causes heat flux on water cooled wall uneven. In virtue of supercharging, mass flow rate of gas inside furnace increases tremendously. In this case, it can not be neglected the ratio of heat flux of conductive heat transfer to total heat transfer on cooled wall and pipes. In addition, simplified furnace structure put in under different output power, and some useful information obtained.