Підвищення енергоефективності обертових печей за використання вогнетривів з теплоізоляцією

Abstract

Rotary heating units are used in many industries for the thermal treatment of bulk raw materials. However, today the utilization rate of fuel in rotary kilns is extremely low. So, for example, the bulk of the clinker is fired in kilns, the thermal efficiency of which does not exceed 55…60 %. In this case, heat losses through the housing to the environment reach 20…35 % of the total heat of combustion of the fuel. One of the main factors determining the thermal efficiency of work is the value of the thermal resistance of the lining. The absence of a strong heat-resistant material with significant heat-insulating properties determined the direction of work on creating a lining with increased thermal resistance by changing the configuration of the refractory and creating a cell for introducing additional heat-insulating material into it. This solution reduces heat loss to the environment and improves the energy efficiency of rotary kilns. In this paper, the thermal efficiency of the lining with different refractory configurations for an operating rotary kiln 4.5х80 m installed in the high-temperature zone of the kiln was studied. A technique, software, and numerical calculations have been developed to determine the temperature and heat flux in a lining with a heat-insulating element and justify the choice of refractory configuration. It has been determined that the installation of refractories with thermal insulation in the zone of maximum temperatures makes it possible to reduce the heat flux into the environment by 26…54 %, and in the furnace as a whole by up to 36 %. A significant advantage of this solution is the fact that increasing the energy efficiency of the furnace does not require additional fuel consumption, temperature increase or increase in the enthalpy of combustion products. The results obtained can be used to design new and improve existing equipment, which will improve the energy efficiency of the furnace and significantly reduce heat loss through the casing to the environment.