Measure And Control Problem Study On Trickling Biofilter For Low Concentration VOCs Removal

At present the study on trickling biofilter for low concentration VOCs (volatile organic compounds) removal mainly focuses on experiment study, germ selection, process theory, dynamics, and multiphase transfer characteristic etc, which just limited in the process simulation and theory explore. However, in biological processing waste gas, the trickling biofilter as a complex metabolize biochemical process system not only have normal characteristic of chemical industry transfer matter but also have the life body's metabolize characteristic, whose process parameter such as the waste gas circle liquid flux, inner purifying temperature, humidity, pH value, bio-bacterium liquid concentration etc and there are many factors impact the process efficiency such as gas-liquid two-phase flux, multi-hole medium structure size etc. These parameter selections have already lacked of theory guidance, at the same time it is difficult to build up math model exactly because of bio-chemical process complexity, uncertainty, chaos and nonlinearity. So it leads to the industry auto- control of bio-technological process behind to other industry process. The study domestic and foreign on process parameter measurement, control and optimum in biological waste gas removal just remain blank.The paper just about the shortage hereinbefore presents using BP arithmetic and NN (neural network) to set up biological low concentration VOCs removal model which establishes the base for optimum control and simulating experiment study, at the same time the NN combined to genetic algorithms could resolve the optimum problem. Aiming at the key application technology in the biological VOCs removal, the paper studied on the biomass concentration measurement and on-line measuring technology, also studied on optimum biofilter process efficiency and the fuzzy control of inner cyclic liquid pH value.①According to the experiment study on trickling biofilter for VOCs removal and biodegradation capability it make the relationship among operating parameter clearly, set up the toluol waste gas removal tester and carry out the experiment of capability influence in biofilter degradation waste gas process.②Using NN, BP arithmetic, Information fusion technology to set up VOCs removal model and study on the simulation experiment, resolve the complex process problem and make the base for the coming optimum control technology.③Combined to the LMBP NN, optimum and genetic algorithms, and extent to optimum germiculture compound or bacterium optimum growth condition, compared to the traditional orthogonal test the result indicate that LMBP NN, optimum and genetic algorithms used in optimum problem can improve efficiency and reduce test times④Set up a new on-line measuring method for biomass concentration and study on the sensor structure theory, light path, theory analyses and experiment. The result indicates that the method is nicety sensitive and long life in measuring animalcule bacterium liquid concentration.⑤According to the associate data among temperature biomass concentration and sensor output voltage, we adopt NN technology to set up equivalent NN model of intelligent sensor, and then get their associate function relation. Under the base, present the new intelligent information acquiring method and do the simulation and experiment study, present the design method of intelligent sensor and information process technology about temperature complement, eliminate the temperature influence on the on-line testing, the concentration measuring relative error is:≤2%, the temperature testing relative error is:≤2.5%, which could meet the precision need of biomass concentration test and temperature test.⑥Present a new biofilm thickness on-line testing method based on the fiber reflection energy attenuation technology, and according to the analyses on sensor design theory and method, the result indicates that the method is nicety sensitive and long life used in the biofilm thickness measuring.⑦The study designed biofilter control system which is composed by 3 parts: the optimum processing efficiency control system, pretreatment control system and pH control system; presented the design idea of optimum processing efficiency control system; adopted BP arithmetic to optimize PID parameter of biofilter VOCs process and render the result compare to the traditional PID control. The simulation result indicated that after BP arithmetic is used the control system is more stable than traditional PID control.⑧Present the realization means of fuzzy controller based on the memory transform technology which used on pH value two-dimension look up table fuzzy controller (LUTFC). The simulation indicates that aiming at the pH control complex process, the LUTFC not only controls very well but also adapts the process very well which exhibits the advantage of LUTFC and the control precision is better than±0.30pH, improve the biodegradation efficiency.