Research On Thermal Expansion And Flue Gas Redirculation Joint System In The Application Of Fluidized Bed Boiler

In modern times, the world demand for energy level is higher and higher withthe rapid economic development. For a big population in our country, the issues ofdemand for energy become more prominent. Fluidized bed boiler in our country, inthe actual operation, is frequently operate under low load，and because of the fluidizedboiler, the primary air is very big, almost having no too big differences as operation atfull load，and then excess air ratio is far exceeds the design value. Fluidized-bed boilerenergy consumption is very high, because of fan power consumption is about1.5~1.8times of general boiler of high oxygen content in flue and a large amount of boiler fluegas loss. Boiler’s own electricity consumption and exhaust loss caused its inefficient.Current conveyor system control scheme is mainly focused on by throttling air volumeto match the boiler load change, throttling loss serious，and uses of the frequencyconversion velocity modulation appears to be very energy efficient, but notfundamentally solve the above problems.Based on the above issues, this topic is presented of thermal expansion joint offlue gas recycle system in application of fluidized bed boiler system, and this systemcan not only significantly reduce electric energy consumption of the unit itself, but alsosignificantly reduces the flue gas loss of fluidized boiler. This system from theconnection way to energy-saving principle and control mode is discussed in detail inthis article.（1）Through the analysis and simplification of the system，boiler efficiency andthe primary air temperature, coefficient of excess air and flue gas temperature with acombined flue gas recycle system with thermal expansion. Related mathematicalmodel is presented, providing the theoretical basis for the Value analysis of the systemand the joint system operation analysis.（2）some key parameters of this system are calculated，including the flue gasrecirculation ratio calculation and calculation of proportion of heat flue gas flow forthermal expansion, to provide basis for control work late. Design and checkingcalculation of the area of the heat exchanger and flue gas ratio for thermal expansionheating and recycled flue gas ratio, Combined with the case, is also given forequipment selection.（3）Joint system in operation making the system more complex，and at the sametime the system is put into operation, we should ensure safe and stable running of thefluidized bed boiler. So, the paper presented a joint system control strategy, controlling excess air coefficient to reach optimal value with thermal expansion systems and flue gas recirculation joint system,given air and coal feeding system control method inaccordance with load situations.（4）the paper gives Yiyuan, Shandong-based calculation of fluidized bed boilerin thermal power plant, drawing a conclusion that Draw2.8%reduction of powerconsumption of boiler blower. It is including that induced draft fan powerconsumption reduced by28%, to reduce exhaust losses18%and boiler comprehensiveannual net efficiencies is going to increase around5%, with remarkable energysavings.