Font Size: a A A

Study On Multi-parameter Measurement And Quality Control Theory And Technology Of Metallurgical Lime Kiln

Posted on:2012-07-12Degree:DoctorType:Dissertation
Country:ChinaCandidate:X G FengFull Text:PDF
GTID:1111330371473641Subject:Precision instruments and machinery
Abstract/Summary:PDF Full Text Request
Steel industry is an important basis for China's national economy and pillar industry. Lime is animportant raw material of steel metallurgy. As a blast furnace and converter steelmaking flux, it canreduce refining time and improve the quality of pig iron and steel purity, etc. And it can be widelyused in the field of environmental protection such as wet flue gas desulphurization and acidicindustrial wastewater treatment field of environmental protection. It is also used in the metallurgicaland chemical production processes such as calcium carbonate, epichlorohydrin, and preparation ofalumina sintering. The main measure of the quality of lime is the degree of activity. The active limeis mainly calcite by metallurgical lime kiln. The activity of lime not only determines the efficiencyand purification degree of flue gas desulfurization and waste water neutralization, also determinesthe product quality, raw material utilization and operating costs of iron and steel smelting, lightcalcium carbonate and alumina sinter and other production processes. With the rapid development ofsteel industry, we need increasing demands on metallurgical lime. Therefore, we need to carry out aresearch on the control theory and technology of metallurgical lime kiln production process quality.Then the whole process can be integrated optimized and be work securely and steadily. This is ofgreat significance on further stabilizing the calcite lime quality, reduce energy consumption, reduceenvironmental pollution, ensure the quality of the steel smelting and improve the economicefficiency.With the research on the physical and chemical mechanism of the process of active limecalcinations, this paper describes the nonlinear multi-variable and multi-parameter productionsystem of the lime-kiln complex nature and the influencing factors of the lime calcimine quality, andanalysis the relationship between the degree of activity indicators of active lime and calcimine time,speed, temperature, fuel ratio and other parameters. On this basis, Baosteel Meishan Iron and SteelCompany sleeve lime will be the targeted, Its gas flow detection, temperature regulation of heatingsystem and optimize control of combustion process will be the object, We are going to use themethod of combining the on-site technical parameters test, simulation analysis and industrial test toget a research on multi-parameter detection and quality control theory and technology of limeproduction so that the entire production process may be comprehensive optimization and worksecurely and steadily. The main contents and innovations are as follows:(1)Use the principle of compensation with the parameter to the design and implement the online detection program of mixed-gas flow.In engineering, we usually use differential pressure orifice flow meter to achieve an on-linedetection on mixed gas flow of metallurgical lime. This paper analyzes the causes of the errors andthe ultrasonic flow meter is proposed as the fiducially flow meter to detect the main gas flow so as to give an on-line detection on each branch pipe. Then it derives the density on-line compensationalgorithm of the mixed gas flow detection, develop a multi-parameter compensated mixed gas flowmeasurement detection scheme and further build the mixed gas flow detection system of on-linecompensation. On this basis, through the hardware configuration, selections, software design,development and site commissioning, this paper elaborate how the entire system is achieve.(2)Aresearch on the soft measurement of oxygen content of the combustion process based onthe information fusion technology.In this paper, as the on-line detection on oxygen content in the exhaust gas of the bestcombustion control system for the lime kiln, the soft measurement based on the information fusiontechnology is used to launch a research. We propose the mechanism modeling scheme of exhaustoxygen content. According to the expression of the mechanism, we detailed analysis the factors ofthe relevant parameters and give the modified formula to calculate the content of oxygen. And wederived the correction formula calculation of oxygen content. On this basis, constructed analysismodel of oxygen soft sensor system based on information fusion.(3)Use the fuzzy control strategy to design a combustion temperature control system.As for the nonlinear, large delay and strong coupling of the lime kiln temperature control for thecombustion process, we use the fuzzy control strategy to build a fuzzy control program for the limekiln temperature control system and further put forward the fuzzy PID control method to solve theexisting problems. Simulation and analysis by MATLAB, we verify the fuzzy PID control strategycan achieve a better dynamic control performance.(4)The metallurgy lime kiln control of combustion process optimization based on theeconomic operation.In this paper, through the analysis of the characteristics of the lime kiln economic burning, weput forward a method of improving the thermal efficiency and real-time adjusting the best air-fuelratio coefficient. Then a comprehensive closed-loop control program of detecting the oxygen contentin the combustion exhaust gas is developed. As a result, when the calorific value of fuel fluctuatesbecause of the changes of heating gas mixing ratio, the amount of excess air can still be optimalcontrol effectively so that the lime kiln production process will be work economically. The paperalso established an optimal control model of lime kiln combustion system with the BP neuralnetwork. Using the genetic algorithm to calculate the connection weights and threshold withoptimization, the accuracy and convergence rate of BP neural network have been improved. As aresult, we achieve the lime kiln production process integration and optimization and work steadily.
Keywords/Search Tags:metallurgy lime kiln, active lime, combustion control, error theory, multiparameterdetection, quality control, optimization
PDF Full Text Request
Related items