Process Intensification Based On Non-Stability Operation Of Nonlinear Bio-Chemical Process

Due to the traditional chemical industry of excessive dependence on non-renewable energy and a series of environmental problems, bio-chemical technologies are developing to replace the traditional chemical technology, and to get industrial products or to achieve the effect of energy conservation and emissions reduction. Non-stability operation technology is a new kind of process intensification technology. The average value of the output of some system under non-stability state operation may better than the output of system under steady state operation, so the new technology can improve process performance and reduce energy consumption, etc. Studying on the bio-chemical process intensification technology is one of the important means to achieve energy saving and emission. So in this paper, two nonlinear bio-chemical processes are chosen as cases to analyze the process intensification based on non-stability operation.The main research contents of this paper are as follows:1 For the selected nonlinear bio-chemical process of ice-cream wastewater treatment of the anaerobic digestion process, set up the modeling of this process at first. It shows that the process is internal stability process through stability analysis. And the system with perturbation of operational variables is studied. The result shows that the output is periodic if the input is periodic, and share the same frequency as the input for the studied nonlinear system; and the process performance is significantly enhanced.2 For the selected nonlinear bio-chemical process of continuous bio-ethanol fermentation process, set up the modeling of this process at first. The stability analysis of single and double parameter bifurcation analysis diagrams show that the process has the self-oscillation region, namely the existence of an internal process unstable region.Select process self-oscillation region midpoint Pd for the design point, and select substrate feed concentration Sf as the operating variable. Putting the mandatory periodic disturbance on the operating variable of the Sf is to make the process stay on non-stability state operation. The effect of amplitude and frequency on the process with mandatory periodic perturbation is analyzed. From the obtained stroboscopic bifurcation diagram and maximum bifurcation diagram, it shows that with the forced disturbance amplitude and frequency change process has different dynamic characteristics. Limit cycle bifurcation analysis is compared with the simulation-based methods, such as stroboscopic and maximum bifurcation maps, and it is proved to be an efficient analyzing tool for obtaining a more efficient and complete characterization of the model behavior. So limit cycle bifurcation is investigated in this paper. From the limit cycle bifurcation diagram, NS bifurcation lead a periodic orbit to an invariant torus, and PD bifurcation lead a periodic orbit to a new orbit with (approximately) doubled period. Meanwhile, the process operation area is divided into three regions, where S1 region is a parameter area which can be enhanced in the process under the condition of ensuring the safety and controllability of the process. Finally, non-stability operation of the bio-ethanol fermentor for improved performance is also discussed. The conclusion is that designing the fermentor to self-oscillatory can obtain higher overall substrate conversion rate than the corresponding steady state situation.In summary, process intensification methods of non-stability operation technology is applying to the bio-chemical processes with non-linear characteristics, and the results showed that the dynamic characteristics of the process not only by itself, but also influenced by the forced disturbance parameters. Meanwhile, the performance of the process has been very good improvement. Therefore, the research on the non-stability operation technology is significant.