Mathematical Model And Control Strategy Of Argon-oxygen Refining Low-carbon Ferrochromee Production Process

In ferroalloy refining process, the end point control is the core of the blowing process,however refining ferroalloy is very complex and multiphase which is carried out under high temperature chemical reaction process of nonlinear physical. There are many uncertain factors, and it is difficult to obtain accurate and continuous detection information, though there are some indirect detection methods, its accuracy can not achieve satisfactory level, refine ferroalloy process and endpoint control has been caused great difficulties . the traditional method is based on empirical observation smelting furnace mouth of the flames and sparks, hot metal into the cumulative volume and oxygen consumption to estimate the carbon end Volume. This approach can not only extend the smelting time, reduce the efficiency of the furnace and smelting, but also the carbon content during the reaction by many uncertain factors, making the smelting process instability directly which affects the final quality of the refining ferroalloy. For these reasons, this in-depth study of the temperature of hot metal detection method, a low-carbon ferrochrome production process of the mathematical model, based on the above two conditions, low carbon ferrochrome smelting process to complete the controller design reasoning, blowing through the timely adjustment The oxygen end of the carbon content of hot metal flow control and end temperature, solution flow rate of the original value of fixed oxygen blowing the issue and realize the dynamic control flow of oxygen blowing, improve the refining effect of the end of hit rate increased to shorten the refining time.The proposed new process is the production of carbon ferrochrome converter based on the reference to the production of stainless steel professional AOD furnace theory and practice. The goal is to ferroalloy smelting production process for a specific object of study, low-carbon ferrochrome production process through the establishment of mathematical model and control strategy for the creation of high carbon molten iron directly to low-carbon ferrochrome production provide theoretical support for the new technology, and creating a Argon Oxygen refining ferroalloy production of energy-saving technology industry precedent to provide technical support, ferroalloy production process to achieve global energy consumption optimization. Based on the above to complete the main objective of this paper are as follows:1. Through reengineering process, high-carbon ferrochrome proposed direct production of liquid low-carbon ferrochrome in the new technology, new processes needs to complet 2 units from the stove to medium high carbon ferrochrome, low carbon ferrochrome production, melted in electric arc furnace in high-carbon ferrochrome, after filling slag, blowing directly into the AOD furnace, AOD furnace with top lance blowing oxygen. Bottom Gun argon oxygen gas mixture, at the top of high pressure oxygen blowing lance to make hot metal decarburization speed, can reduce the refining time, improving production capacity, blown by bottom gun control different ratios of oxygen and argon mixed gas, reduce carbon monoxide in sub-pressure, the decarburization reaction forward and the achievement of the purpose of lowering carbon chromium security, with project implementation, creating a saving of argon oxygen refining process ferroalloy industry precedent.2.As a multi-phase pyre-metallurgical process, alloy side and top combined blowing AOD refining process is very complicated. Noted that the refining process of physical and chemical properties, including its thermodynamic and kinetic features, consider the system of mass and heat balance, refining the process of isothermal state, through the mechanism analysis, study and master the hot metal temperature, gas velocity, oxidation Response speed, mobility and other parameters of hot metal coupling relationship established with the hot metal oxygen decarbonization rate of speed, temperature, oxygen supply rate and the mathematical model between hot metal; for argon between the rate and the mathematical model of hot metal temperature. Gray system modeling method, a hot metal for the decarbonization rate and rate of argon between the mathematical model. The model can be carried out with basic-level automation with the whole process of decarbonization oxygen flow automatic control, the results of the model to adjust oxygen blowing operation flow, strengthen the role of bottom-blowing gas mixing, and further improve the hot metal - slag reaction, so that the molten pool composition and temperature inhomogeneity be effectively improved, carbon and oxygen reaction step closer to balance and improve the endpoint temperature and composition of the hit rate and reduce the oxygen blowing end product, to avoid the hot metal chromium peroxide to improve the alloy, metal collection Yield and quality of molten iron, thus obtain is better results of decarburization than the optimal gas consumption, longer lining life, the transformation for small AOD furnace to provide a theoretical basis.3.Used as a secondary output selection of hot metal temperature, hot metal carbon content as the main output, by comparing the PID control algorithm and inference control algorithm to control the temperature and then control the end of hot metal hot metal carbon content, theoretical proof of the inference control algorithm is better than PID control algorithm. By the end of inferential control algorithm to control the temperature and carbon content of molten iron, through theory proved, obtained control of inferential control endpoint temperature and carbon content of molten iron, fast settling time without overshoot, has strong robustness, and can eliminate Steady-state deviation.4. Development of low carbon ferrochrome production of argon oxygen refining process of implementation of DCS control systems and related issues. Control system consists of two components, the first-class dual-CPU IPC to deal with complex data operations, centralized operation of surveillance; centralized operation to monitor use of the Siemens MP377-15 touch screen as the monitor interface, PROFIBUS-DP and MPI through the composition of real-time bus Communication network for data communication with the underlying PLC. In order to achieve decentralized control, centralized management and monitoring functions; the second level with 3 sets of Siemens S7-300 series PLC, the control system is divided into five subsystems, namely, tilting the furnace control system, top gun lift control system, top gun Gas flow control system, the end of the gun gas flow control system, the feeding control system. 5 share control subsystem and the central controller 3 sets produced by Siemens S7-300 programmable logic controller, Production line control system for automatic control of the device. The end of the gun which the central controller and gas flow control system share a table produced S7300 Siemens programmable logic controller, tilting the furnace control system and the top gun lift control system, the end of the gun gas flow control system share a programmable logic controller, the feeding control system 1 set S7300 alone programmable logic controller, the system has been put into production, stable and reliable operation. AOD furnace hot metal temperature of line detection methods, uncertainty caused by background radiation emissivity fluctuations is proposed based on principle and bold color temperature isothermal theory of bottom gun cavity temperature, stabilization of the molten iron of the emissivity. Application of curve regression based on least squares method to achieve infrared temperature measurement device calibration, temperature compensation complete. By refining furnace in the sample proved bottom gun of temperature measurement system with high accuracy and repeatability to meet the requirements of actual production.