Application Research Of Fuzzy Control To Automatic Control Of Bag Dedust System

Bagfilter dedust technology becomes dominant more and more in the field of industrial flue dust treatment.Research on automatic control technology is indispensable to promote the bagfilter dedust technology and its application.Due to complex and diverse parameters of bagfilter dedust system,it is difficult to build up its mathematical model using typical control theory or modern control theory.So at present simple control mode has been adopted widely,such as two bit type adjustment,which is difficult to let dedust system work stably in optimum condition with high efficiency.In this dissertation,fuzzy control theory and method has been researched in automatic control application of bagfilter dedust system.1. Briefly introduce bagfilter dedust technology.Analyse status in quo and development of automatic control technology on bagfilter dedust technology.Complex and diverse parameters,wide fluctuation of work condition which control of dedust system is faced with,it is difficult to build up its mathematical model direct from point of view of dedust process and control theory,at present generally adopted adjustment mode is simple.According to present status above,put forth fuzzy control theory and method applying to automatic control of bagfilter dedust system.2. Conclude basic requirements of automatic control of dedust system.Integrate knowledges and experiences of experts on dedust with the theory and method of experts on control,design resistence fuzzy controller of deduster and flue gas temperature fuzzy controller.3. Adopt software method in medium and small scale programmable controllers,realize resistence fuzzy control of deduster and flue gas temperature fuzzy control.lt is not only simple and economical,but also very reliable.4. Compared with traditional resistence timing/determined pressure drop control of deduster,resistance fuzzy control dimly deduces resistance control target value according to flue gas flowrate variation of dedust system,then dimly deduces cleaning period and pulse interval according to the deviation between actual resistance and control target value. Do not produce phenomena that dust primary layer is destroied because flue gas flowrate varies but cleaning frequency doesn't change.That can let deduster maintain all along the state of the highest removal efficiency and optimum air draft flowrate.5. Flue gas temperature fuzzy control dimly deduces turndown ratio of mixer valve according to temperature values of multipoints and their variations.Not only prevents burning bags at high temperature and dewing at low temperature,but also lets mixing airflow adjust to the optimum value.Do not produce case that system flue dust collecting effect decreases due to excessive mixing airflow.6. The application examples show that: In the bagfilter dedust system for 5 ton electric furnace,mixing airflow when adopting flue gas temperature fuzzy control is more reasonable than that when adopting ordinary temperature two-bit typeadjustment.lt can reduce 30% of mixing airflow,improve 10-20% of total flue gas collecting efficiency.In the bagfilter dedust system for 100 ton electric furnace,dedust system is more stable and cleaning energy consumption decreases when adopting deduster resistance fuzzy control than that when adopting ordinary timing or determined pressure drop cleaning. In normal condition, emission concentration decreases from ordinary less than 50mg/Nm3 to less than 20mg/Nm3.