Oil refineries, which are the main centers of energy products in the country, use about 1% of refined oil as fuel. In a refinery where about 100,000 barrels of crude oil are refined daily, it is especially important to study the refinery’s energy consumption and find ways to save energy. In a refinery, in order to convert crude oil into different materials, it is necessary to go through a series of special processes, which are more efficient at high temperatures or do not occur at low temperatures. That is why the furnace is one of the main parts in the refinery. About 75% of the energy from hydrocarbon fuels used in refineries is consumed in furnaces, so simulation and accurate design of furnaces is one of the most important steps in reducing the energy consumption of these industrial units.
Furnaces are among the equipment that play a major role in industry. Almost no industry can be found that does not use furnaces. The main parts of a furnace include the combustion chamber, the burners, the displacement part, the chimney, the auxiliary equipment for entering the air and fuel, as well as the measuring and control devices. Figure (1) shows a simple diagram of a furnace with its various parts. The furnace has equipment by which heat from the combustion of fuel is transferred to the process fluid inside an insulated chamber. In the combustion process in furnaces, air and fuel are directed into the furnace and mixed with each other in various ways, and in the presence of a heat source or spark, oxygen and fuel are combined and the combustion process takes place.
Fig (1): Furnace Simple diagram
Combustion gases pass through the displacement section and enter the open air through the chimney. The main task of the furnace is to supply a certain amount of heat to the process fluid under high temperatures. The main cause of heat transfer is the radiation mechanism. If economically justified in a separate section, the heat of the combustion exhaust gases is transferred to the pipes in the form of displacement.