| In the rolling production process of titanium coiled sheet cold rolling, acid cleaning is the necessary working procedure to be important, the main effect of acid is removing the surface oxide and contaminants of titanium belt after hot rolling, and get titanium belt with the surface cleaning to prevent defect in rolling.In the existing production process of titanium belt acid cleaning, coal combustion heats boiler to produce water vapor of high temperature, using of graphite heat exchanger the heat of high temperature steam is transmited on each process medium solution of acid cleaning,and heats up the solution to the desired temperature to meet the technical requirements, and then the titanium belt is cleaned. However, there are many problems in the heating,the shock resistance of graphite of graphite heat exchanger is lower,so the graphite is easy to cause to damage in the transportation, installation and concrete work and needs regular maintenance; graphite heat exchanger may be fracture when it is badly damaged,if the graphite-pipe is fracture when the acid enters it, the cracked graphite-pipe is able to be find when it has no option but to break vacuum,reduce temperature,release acid and come in water for leaking test,that wastes materials and takes up booting time which greatly reduce the production capacity; in the heating process, heat by fuel combustion,high temperature steam produced by boiler and pass through by pipeline transport, transfers to each process medium solution by graphite heat exchanger,and the transferring process is so repeatedly that the heat utilization ratio is very low and causes high production costs and great waste of energy;the flue gases by coal combustion contains a lot of soot, sulfur and nitrogen oxides and other harmful substances,and noise pollution and water pollution caused by boiler,are serious harmful to the environment and human health; simultaneously, with global warming and greenhouse effect aggravate, excessive carbon emission would reduce the competitiveness of products and seriously obstruct long-term development of enterprise. Therefore,it is demanded to develop a new type,highly active and environmentally friendly way of heating.In this paper, in order to solve the above problems, microwave heating as a new heating mode, was employed to take the place of tradition heating method. Microwave heating which had extensive advantage can solve several problems at the same time. It is significance for the long-term development, energy use and environmental protection of the factories. The main contents and conclusions are as follow:Three kinds of typical solution were investigated by microwave irradiation; the characteristics of temperature increasing in microwave field were obtained. Response surface methodology (RSM) was employed to optimize process of microwave heating of pickle, aimed at controlling a proper temperature of pickle solution for the manufacture by microwave heating and making the microwave energy efficient. The optimized results were obtained:microwave power of 730.18W, the volume of pickle solution of 333.17 Ml, the concentration of pickle solution was 172.94g/L, the experimental value of pickle temperature was 64℃that was close to the predicted value which was 64.99℃. The deviation between them was -0.98% which justified that the model is suitable to modify this situation.New technology of microwave heating of pickle was raised in our paper. And new kind of microwave heating device, instead of the traditional steam heating system, was employed to the heating of pickle. This is the first time for the microwave technology to be applied to the pickle heating process in the domestic. The heating rate was increased; the pickle temperature was controlled more accurately and it is no emissions of soot. Otherwise, new kind of microwave heating device was invented according to the request of our new technology. The device was proved to be feasible and reasonable in the industrial experiment.The acid cleaning experiments of titanium plate were carried out and the results indicated that:the surface of the titanium band was converted during the hot rolling process into an uneven oxidation coating which would be more stronger after the rolling and bonding process. Once the coating was completely removed away, the surface of the titanium band was turned out to be rugged which is recognized as over wash. Pretreatment was carried to remove part of the oxidation and destroy the dense oxidation coating. Then the oxidation acts with the pickle more easily which reduces the pickle consumption, improves picking efficiency, and reduces the picking time. According to the concentration of the pickle solution, reaction rate was estimated as follow:7×10-4g/s for 10g/L HF, 4.3×10-3g/L for 20g/L HF and 6.4×10-3g/L for 30g/L HF.From our investigation, microwave heating of pickle is a new technology worth well to be promoted. At the same time, the successful development of this technology opens a broad field for microwave energy application. |
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