INFLUENCE OF THE METHOD OF NATURAL GAS SUPPLYING ON GAS DYNAMICS AND HEAT TRANSFER IN AIR TUYERE OF BLAST FURNACE

Abstract

. The use of natural gas reduces the amount of coke to produce pig iron. The flow of hot blast pushes natural gas to the surface of blowing channel in the conventional tuyere. Natural gas is poorly mixed with natural gas. This causes incomplete natural gas combus-363 tion and pyro lysis. Therefore, the problem of the completeness of combustion of natural gas is relevant. One way to improve the mixing of natural gas and hot blast is the gas pipe in the blow channel. However, dynamics and change of the thermal state of the tuyere are understudied for this option. The possibility of ignition of natural gas inside tuyeres must also be taken into account. The authors have in-vestigated the infl uence of the method of natural gas supplying on gas dynamics and heat transfer in air tuyere of a blast furnace with the help of modeling in ANSYS Fluent 15.0.7. Simplifying assumptions were adopted. Only fluid inside the blowing channel is considered as the modeling zone, and the processes of heat transfer to the water of cooling system are considered in the extended boundary conditions. A simplified diagram of the compu tational domain was created in DesignModeler and a computational mesh – in AnsysMeshing. The boundary conditions were set for blowing, natural gas, and also for the border of the fluid with copper walls. The calculations were carried out for half of the tuyere. It is shown that under the given conditions of flow of air and natural gas, combustion inside tuyere with extended to mid-channel gas blowing nozzle does not occur, and natural gas is mixed with the hot air. Improving the mixing of natural gas and hot air, one side, reduces heat flow at the exit of the blowing channel and the average temperature of the gas mixture, on the other side, creates conditions for complete combustion of natural gas outside the tuyere.