| Blast Furnace Top Gas Pressure Recovery Turbine Unit (TRT) is widely acceptedas an effective secondary energy recycle device by domestic and international ironand steel enterprises. It works by flowing the blast furnace top gas into an actingturboexpander, then converting the pressure and heat energy of the top gas tomechanical energy, and finally driving electrical generators. It recycles considerableenergy, which is wasted in decompression valve group of traditional blast furnaceprocess flow, to use TRT unit instead of decompression valve group, withoutdegrading the quality of top gas or influencing gas consumer's normal use. It is atypical energy-saving and green project as it has significant economical benefits andmeanwhile reduces noise during the process.As an energy recycle device, the precondition of applying a TRT unit is thestability of blast furnace's top gas pressure during operation, and thus no disturbancewill be introduced to the main process. At present, the most popular method tostabilize the top gas pressure is the empirical PID control of the adjustable static bladeopening. However, with modern ironmaking technology's development and blastfurnace's expansion, the demand on top pressure stability becomes increasingly high.And the PID control is no longer able to achieve the expected control requirements.Therefore, the stability of top pressure requires researching systematically.Study on Top pressure stability is the base of research on stability during thewhole TRT operation. Therefore, this thesis takes the TRT system under normalcondition as its research object, and presents the dynamical modeling and controlmethod of top gas pressure. The main contents of this thesis are as follows:(1) The process technology flow, principle and operating precondition of TRTunit are introduced. Then the control techniques of top pressure in TRT unit, the statusof theoretical study on top pressure stability and the characteristics and nonlinearcontrol of electro-hydraulic position servo system in TRT unit are summarized.(2) Considering the characteristics of normal condition, TRT unit is simplified reasonably. Blast Furnace feeding is the dominant factor that influences the top gaspressure in TRT unit under normal condition. This disturbance is considered to get adynamical model of the TRT system under normal condition by mechanism analysisand parameter identification based on data from industrial field. The identifiablecondition of closed-loop control system of top gas pressure is analyzed and thissystem can meet the condition. Validating experiments are carried out on this dynamicmodel, and simulation results show that the model can reflect the normal situation oftop gas pressure correctly.(3) It's a key problem to design a high performance electro-hydraulic positionservo control system for improving control precision for top gas pressure in TRTsystem. Aiming at the nonlinear characteristic of electro-hydraulic position servosystem, a nonlinear state feedback method is adopted to linearize its mathematicalmodel exactly, and then optimal controller is proposed. The simulation experimentsare carried out on empty and load system respectively. The results show thatexact-linearization optimal control method is valid.(4) Based on the established model of top pressure in TRT system under normalcondition, a two-degree-of-freedom intemal model controller is designed for top gas.The simulation experiments are carried out on matching and mismatching models, andIMC controller adjustable parameters' impact on the system performance is discussed.The results show that IMC method has good performances and the adjustment of itsparameters is easy. In addition, the system robustness can be adjusted by tuningcontrol parameters. And it is fit for engineering application.(5) The main control functions, hardware configuration and software design ofTRT automatic control system which is applied in industrial field are introduced.Finally, the work of this thesis and the further research directions aresummarized. |
PDF Full Text Request