Research On Pressure Control System In Slurry Preheating Of High-pressure Acid Leaching

Slurry preheating process is the fundamental and key process of high-pressure acid leaching(HPAL)process and the stability of its parameters determines whether HPAL process can be safe and efficient.Current research on HPAL process mainly focuses on the implementation of the project and not in view of the complex working conditions from the scene,lacking the support of field data,inevitably in the implementation process in the presence of control effect is not ideal.A nickel cobalt smelting plant HPAL slurry preheating zone,in the field of cold water test,slurry preheater using single PID level control and the system can meet the requirements,but in hot water test the process oscillates and seriously affects the operation test.Later changed to liquid level-flow cascade PID control,the effect has been improved,but still failed to completely solve the problem,the scene had damage to the pump.It's urgent to find a new solution to stabilize HPAL process Technology parameter index.Through the analysis of related literatures and related design documents,on the basis of the collected a large number of field data,this thesis made the following several aspects of the work:(1)Analyzed the causes of level and flow fluctuations and shortages of existing control strategy.From interrelated factors of HPAL process variables,taking the high temperature preheater as analysis object and reviewing history curves one by one,we find out the influence of preheater feed flow and its level.At the same time in order to further suppress preheater pressure fluctuations,we find out the influence factors of the preheater pressure fluctuations.(2)Established the high temperature slurry preheater pressure simplified model in the vicinity of the steady state value 600Kpa.(3)Based on the analysis of the factors of preheater level and flow fluctuations,in order suppress the fluctuation of pressure in advance,we put forward two solutions:reduce the pressure fluctuation by smooth switching between fuzzy PID compound control and compensate the disturbance to the effect of pressure by introducing disturbance observer based on PID control.(4)Connected the established fuzzy controller,disturbance observer and pressure process model in Matlab and PID controller in Plantcruise,by simulation experiment and comparing the conventional PID control,fuzzy PID compound control and the PID control based on disturbance observer,we get the effectiveness and superiority of these three kinds of methods in the process of steady pressure.