Research And Design Of Deep Adjustment Control System For Cylinder Cutting Of 350MW CFB Unit

The thermoelectric decoupling system of 350 MW circulating fluidized bed(CFB)unit in a coal-fired power plant under deep peak regulation is studied and analyzed.Through the theoretical analysis of the existing thermoelectrolytic coupling technology and the energy flow model on the side of the steam turbine,it is determined that the technical means of deep peak regulation and thermoelectric decoupling is low pressure cylinder cutting.In the actual operation of the cylinder cutter,the regulation mode only depends on the thermal control operator to carry out manually,and in the adjustment process,it is necessary to take into account the load change required by the heat network and the limitation of the middle discharge pressure at the same time,so it needs a certain amount of human support,and the operation proficiency and operation habits of different staff will also produce differences in regulation effect,resulting in unstable operation of the unit.In addition,frequency modulation can not be carried out when the load of conventional CFB units is below 175 MW,so the key to realize more safe and stable operation of thermoelectrolytic coupling system under winter heating mode of similar CFB units and the ability of peak regulation and frequency modulation at the same time is to solve the problem of automatic regulation and control of low pressure cylinder cutting system.There is great uncertainty in the conventional cylinder cutting process.Generally,for the units modified by the cylinder cutting flexibility technology,because the advanced intelligent control algorithm is applied to the DCS system of the current power plant,it is difficult to embed and implement these intelligent control algorithms,considering the safety of the system and the influence of the actual software and hardware conditions of the unit control system.In view of this situation,with the combination of control theory,expert experience and actual engineering operation project,a single-mode three-state automatic adjusting control system for cylinder cutting is proposed,which is suitable for on-site implementation.The main contents are as follows:The whole automatic control system is carried out by regulating and controlling the bypass(BPV)valve of the medium and low pressure cylinder connecting pipe,which specifically relates to the heating and extraction(LEV)valve in the winter heating period mode,the(CV)valve of the middle and low pressure cylinder connecting pipe main circuit,and the three-state control of the bypass(BPV)valve of the medium and low pressure cylinder connecting pipe.On the basis of ensuring the safety and stability of the four core control elements: electric load,the heat load,medium discharge pressure and low pressure cylinder intake pressure,the steam extraction frequency modulation is controlled by BPV valve,the middle discharge pressure is controlled by CV valve,and the heat supply is controlled by LEV valve.By designing the control logic and combining it with Emerson DCS system,after debugging and operation,the system greatly improves the degree of automation,makes FM faster,realizes the safe and stable operation of cylinder cutting in heating mode,and improves the economy of power plant to a certain extent.The research results of this subject have been successfully applied to the low-pressure cylinder cutting system of a CFB unit of 350 MW,and the application effect is remarkable,and it has a certain popularization and application prospect.