Application of Accumulative Storage Combustion Technology on Oven Basket in Steel Plant
Abstract
Basket baking furnace is a major process in steel plants. As the temperature requirements of the material are relatively high, the fuel consumption of the basket baking furnace is relatively large, and the emissions generated during the process has caused serious environmental pollution. The current hot-fired combustion technology has numerous deficiencies such as high energy consumption, high emissions, and low thermal efficiency. In this paper, we introduce the application of the accumulative storage combustion technology in the basket baking furnace of steel plant, and analyze and compare the advantages of this technology. The application of the accumulative storage combustion technology makes the furnace temperature more stable, increases the temperature control accuracy, reduces motor electricity consumption, and can reduce air pollutant emissions, which can significantly improve the comprehensive energy utilization efficiency of oven.
Keywords: accumulative storage combustion technology; basket baking furnace; steel plant
1 Introduction
In the steel mill, the basket baking furnace is the process for baking the product with required high temperature. This baking furnace has a relatively high fuel consumption and produces a large amount of emissions during the burning process, which causes serious environmental pollution. With the development of science and technology and the improvement of environmental protection requirements, the emission control of chemicals and energy resources have been taken more seriously. Traditional hot-fired combustion technology has many weaknesses, such as high emissions, high energy consumption and low thermal efficiency. The accumulative storage combustion technology is a new combustion technical method by combining the thermal energy storage technology and burners, which need accurate temperature control. This technology has the advantages of high thermal efficiency, low emissions and stable running, and has become an effective way to solve the environmental pollution. This paper introduces the application of the accumulative storage combustion technology on the oven basket in the steel plant, which provides a new way for the efficient use of energy and the protection of environment.
2 Chemical reaction features of accumulative storage combustion in oven basket furnace
The accumulative storage combustion technology is a combustor using fresh heat storage body to release and capture thermal energy[1-3]. The storage body is fully heated by fuel gas and is marked at about 800℃ before injection, and the fresh heat storage fuel is put into the fresh heat storage body by the refilling cycle. The emission rate of fresh heat storage fuel from the fresh heat storage body is determined by the mass flow rate of hot loads at the output end and the mass flow rate of fuel gas controlled by the actuator of the combustion device. The combustion of the fresh heat storage fuel completely turns into thermal energy, which is absorbed by the physical heat storage body(PSB) [4]. The heat energy stored in the PSB will be released, and this heat energy will help reduce the fuel consumption in combustion process. The specific reaction of the accumulative storage combustion technology is shown in Figure 1, where CNR is a combustor of the fresh heat storage, where H is the heat energy absorbed by fresh heat storage molecule, PSB is a heat storage body and HR is the heat energy released from PSB.
Figure 1. The accumulative storage combustion reaction process
3 Advantages of accumulative storage combustion technology
With the application of accumulative storage combustion technology, the oven basket furnace will have many advantages.
(1) Stable furnace temperature
The accumulative storage combustion technology can adjust the mass flow rate of fresh heat storage fuel to ensure the temperature of the PSB is close to the set value. When its temperature is lower than the set value, the fuel gas mass flow rate is increased and fill more heat storage particles into the oven; When the temperature of PSB is higher than the set value, the fuel gas mass flow rate is reduced and the replenishment rate of fuel particles is reduced [5]. The temperature of PSB can be accurately controlled and the output of thermal energy is stable, so the furnace temperature is more stable.
(2) Increased temperature control accuracy
The accumulative storage combustion technology can continuously adjust the output energy by adjusting the replenishment rate of fuel particles, so the temperature control accuracy can be improved to ±3℃ [6]. The temperature control accuracy of traditional hot-fired technology is about ±20℃, which significantly reduced the difference between the required and the actual temperature of the material.
(3) Reduced motor electricity consumption
Under the condition of accumulative storage combustion technology, the heat storage body is heated to a certain temperature before the injection of fresh heat storage fuel, so that the combustion energy of the material reaches the furnace quickly, which reduces the energy lost due to the work of fan motor. Therefore, the accumulative storage combustion technology can reduce the fan motor electricity consumption by 10%, which is of great benefit to energy saving.
(4) Reduced air pollutant emissions
Under the traditional hot combustion technology, air pollutant emissions per unit product is too high, and the specific CO2 emission amount is 3500-4500m3/t. However, under the accumulative storage combustion technology, the combustion efficiency of fresh heat storage fuel is advancing and the temperature is stable, so the emission amount of pollutants can be controlled with less. For example, the specific CO2 emission amount is only 2600-3000m3/t.
4 Application prospect of accumulative storage combustion technology in oven basket furnace
From the application of accumulative storage combustion technology in the oven basket furnace, it can be seen that its advantages of high thermal efficiency, stable running, low emissions and low energy consumption are very comprehensive. It can greatly reduce the emissions during the burning process and improve the comprehensive energy utilization efficiency of oven basket furnace. In addition, the accumulative storage combustion technology has wide application prospects in various combustion and baking furnaces, such as drying furnace, heat treatment furnace, heat-resistant furnace, etc. [7]. With the improvement of environmental protection requirements, this technology may become one of the most commonly used technologies in the future.
5 Conclusion
The application of accumulative storage combustion technology on oven basket furnace has great advantages. This technology can improve the temperature control accuracy, reduce the power consumption of fan motor, reduce the total pollutant emission, and improve the comprehensive energy utilization efficiency of oven basket furnace. In the future, as the environmental protection requirements continue to increase, this technology will become an important technical measure for energy conservation and emission reduction in the furnace and smelting process.
