Research On Advanced Control And Optimization For HT-L Gasifier

As a typical representative of dry powder coal gasification technology,HT-L gasifier has completely independent intellectual property rights and is a key research object of domestic coal gasification technology.Through production links such as preparation of coal powder,pressurized transportation,gasification reaction,synthesis gas washing,slag and ash water treatment,HT-L gasifier produces and prepares effective gas,including CO and H2.The gasification reaction is the most critical part of the entire production process,which determines the operating quality and efficiency of the HT-L gasifier.The gasifier system is characterized with multi variables,long time constants,time varying and nonlinearity.At present,manual control is generally used in the production process of HT-L gasifier.As a result,the process is limited by the uneven technical level of operators,contributing to large fluctuations in working conditions,excessive consumption of raw materials,and low effective gas output.This dissertation takes the HT-L gasifier of a coal chemical enterprise as the research object,and fully understands the characteristics.Combined with on-site technology and equipment,the dissertation analyzes the requirements of on-site working conditions,designs and implementations the HT-L gasifier advanced control and optimization system with proper controlled variables.The advanced control and optimization system has been successfully applied to a coal chemical company,which obtains better application effects.The research and development work of this dissertation is mainly divided into the following three points:1.According to the characteristics of long time constants,time varying and nonlinearity of the gasification process of the HT-L gasifier,the effective gas content is selected as the main criterion instead of the gasification temperature,and the parameter model is identified online by the recursive least square method.A gasification temperature cascade control scheme is designed.The valve opening of the coal feeder-the coal feed amount is used as the inner loop to construct the inner loop PID controller,and the coal feed amount-the effective gas content is used as the outer loop to construct the outer loop GPC controller.As a result,the control problem of stable gasification temperature has been solved well.2.The design and realization of the optimization scheme for the HT-L gasifier production rate is completed.In order to meet the needs of energy saving and economic efficiency,the "HT-L gasifier production rate" is proposed to characterize the gasification efficiency.The GRNN model of the relationship between the oxygen-to-coal ratio and the HT-L gasifier production rate is established to accurately predict production rate.The genetic algorithm is used to optimize the production rate extreme value,find the best oxygen-to-coal ratio and steam-to-coal ratio,and improve the gasification efficiency.3.On the basis of the original control system on site,an advanced control and optimization system for HT-L gasifier is designed and realized.A hardware platform is constructed.The dissertation adops three-tier architecture design to realize the control and optimization system software platform,including the user interface layer,the business logic layer with the six modules and the data access layer.The system has been put into practice.The commissioning results show that the control quality of key parameters such as the gasification temperature and gasification efficiency have been improved,realizing stable operation of gasifier and significant energy-saving effects.