Experimental Study On Waste Heat Recovery Of Reduction Process In Titanium Sponge Production

The production of titanium sponge in China and foreign countries is primarily using magnesium reduction-vacuum distillation method(also known as Kroll method or combined method).In this method, the reduction-distillation step and magnesium electrolysis step are two main energy-consuming process, our titanium sponge enterprises have already done a lot of fruitful work in the equipment modification, optimization of process operation and other energy-saving technologies, but we do not recycle the waste heat resource in reduction-distillation step and magnesium electrolysis step.The paper is aimed at the gap for energy consumption level of the reduction of sponge titanium production between the advanced countries such as Japan and other advanced countries, developing the waste heat resource recovery experiment, the main work is as follows:Firstly, the waste heat air resource of the reduction process is studied, Using the first law of thermodynamics and thermodynamic test to calculate and analyze the cooling parameters of cooling air in the reduction process. The test show that: the waste heat resource is distributed generation, causing the problem that distribution of temperature is not concentrated, Analyzing the temperature, flow rate and heat dissipation power of the waste heat air in reducing equipment statically, and calculating its confidence interval to get the fluctuation range of waste heat resource parameters.Secondly, to get the main parameters of heat exchange equipment, this paper use Thermodynamic calculation and structure layout design for Tube heat exchanger and heat pipe exchanger which is used in waste heat recycling. comparing and analyzing the performance and the advantages and disadvantages of the two heat exchangers shows that: the heat transfer area of the tube heat exchanger is large and its adaptability is strong, However, the heat pipe exchanger which costs relatively high has obvious advantages in various aspects, such as the waste heat recovery efficiency, the pressure loss, the prevention of the blockage, the cleaning, the life and so on.Finally, according to the generation and distribution of waste heat resource, choosing suitable materials and fluid media to design the tube heat exchanger and the heat pipe exchanger. The experimental study of waste heat recovery carried out in Reduction distillation furnace at one of domestic titanium factories with the designed exchangers shows that: From the fluctuation of the recovery efficiency, we can conclude that the recovery efficiency is low at the prophase, and it goes steady after the production becomes steady. While the production going stable, the hot water temperature of the tube heat exchanger fluctuates between 70℃ and 75℃, and the instantaneous mass flow concentrates in the 810kg/h~870kg/h region mainly; compare to the heat pipe exchanger which hot water temperature fluctuates between 85 and 90℃ ℃, and its instantaneous mass flow concentrates in the 800kg/h~900kg/h region mainly. It shows that the waste heat recovery temperature of heat pipe exchanger is higher.The research results of this paper have been successfully applied in the industrialization of sponge titanium enterprise, it is of great significance for the further strengthening of titanium industry energy saving and reducing emissions, improving the competitiveness of titanium sponge enterprises and products, and improving the resource and energy using efficiency in production process of titanium sponge.