| Steelmaking slag is the inevitable byproduct from the steel manufacturing processes.Each ton of steel will generate about 120-140 kg slag which contains approximately 10% steel.Its components are similar with those of the Portland cement clinker.After fine grinding,it will possess hydraulic cementing feature and is a valuable building material.With the annual growth of the domestic steel,the output of the steelmaking slag is also increasing correspondingly.However,the comprehensive utilization ratio of it is only 22%.According to the incomplete statistics,the cumulative dump quantity over the recent years amounts to 500,000,000 tons.It is calculated that 10,000 tons of the steelmaking slag would occupy 666.67?,meaning that the total area taken by the slag over the years will reach 33333333 ?.Moreover,further 4,133,333 ? land will be occupied by the newly produced steelmaking slag every year.It is of great waste for not being able to recycle them.The state attaches great importance to the integrated use of resources.The State Council issued the No.22 Document in 2005,namely Opinions on Accelerating the Development of Recycling Economy,and the National Development and Reform Commission published No.538 Document titled Opinions on Planning of Comprehensive Utilization of Resources in 2006.Both papers have pointed out that the comprehensive utilization rate of the industrial solid waste should reach 60% or more and that of the smelting slag to 80%.National Demonstration List of Advanced Pollution Prevention Technology in 2008 and 2009 issued by the Ministry of Environmental Protection both enlisted the thermal process system of steel slag and the steel slag power technology,both of which have been promoted in China in an effort to push forward the ‘zero discharge' work.The article makes an intensive study on the electrical part of the circulating water supply used in the thermal process system of steel slag,including several aspects as follows:(1)The paper introduces the main techniques used in the steelmaking slag processing system from the MCC Energy Conservation and Environmental Protection Company and analyzes their working principles and characteristics,as well as the current situation of the constant pressure water supply system with frequency changer at home and abroad along with its working principles.It also makes a detailed demonstration of our company's thermal process system of steel slag design proposal for BOO project as part of the Baosteel's Zhanjiang Steel and Iron Base.A further explanation for the PID control,its core technique,is given as well.(2)The article will carry out the thorough research on the self-developed techniques for the BOO Environmental Protection Project by the MCC Energy Conservation and Environmental Protection Company,including the electrical part of the steel slag processing,production management,and control system design as well as how to realize it.Relying on the upper HIM and lower PLC,the system aims to accomplish the full-automatic control toward the steelmaking slag processing,eliminating all the papery reports by utilizing the computers to manage and control the targeted techniques.Remote automatic circulating water supply management function as part of the thermal process system of steel slag has realized the strictly requested constant pressure,automatic control for the constant flow of thermal water supply and software-controlled PID water supply control.The operators are able to track the processing of the slag bath to guarantee the complete processing under any circumstance tractable. |
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