直流过热刺刀管式蒸汽发生器设计分析

Design analysis of once-through superheated bayonet tube steam generator

采用直流过热刺刀管式蒸汽发生器作为自然循环池式铅铋快堆的主蒸汽发生器。刺刀管式蒸汽发生器传热管由内外两根管同心组成,使得环形通道内工质与内管工质及壳侧工质同时换热,造成设计困难。提出了刺刀管式蒸汽发生器离散式设计方法,,并利用该方法设计了热功率为37.5 MW的直流过热式刺刀管式蒸汽发生器。从换热管数量、环形通道尺寸、内管保温层的导热系数三个方面对刺刀管式蒸汽发生器进行了设计分析,同时采用JF因子对蒸汽发生器的综合性能进行评价。研究表明,当换热管数量由244根增加到550根,一次侧流阻由40 kPa下降至5 kPa,JF因子增加0.4,蒸汽发生器性能提升;环形通道宽度增加0.5 mm,换热段长度增加10%左右,总传热系数和JF因子分别下降13%和14%,蒸汽发生器性能下降;内管保温层导热系数与换热段长度成线性关系,保温导热系数增加,蒸汽发生器的综合性能下降。因此,刺刀管式蒸汽发生器设计宜采用较多的换热管数量、导热系数较小的内管保层材料,同时选择合适的环形通道尺寸,获得最佳的JF因子值。

The superheated bayonet tube steam generator(SG)was applied to the natural circulation pool type lead-bismuth fast reactor.The bayonet tube steam generator is composed of two concentric inner and outer tubes,which causes simultaneous heat exchange of the fluid in annular channel with the fluid in the tube and shell side fluid,resulting in design difficulties.An innovative discrete design method for the bayonet tube steam generator was proposed,and this method was used to design an once-through overheated-bayonet steam generator with a thermal power of 37.5 MW.The design analysis of the bayonet tube type steam generator was conducted in three aspects of tube numbers,annular channel size and heat conductivity coefficient of inner tube insulation.Also,JF factor was used to evaluate the comprehensive performance of the steam generator.The research shows that when the number of heat exchange tubes increases from 244 to 550,the primary side flow resistance decreases from 40 kPa to 5 kPa,and the JF factor increases by 0.4,the performance of the steam generator is improved;When the width of the annular channel increases by 0.5 mm,the height of the heat exchange section increases by about 10%,the total heat transfer coefficient and JF factor decreases by 13%and 14%,respectively,the performance of the steam generator decreases.The thermal conductivity of the inner tube insulation layer is proportional to the height of the heat exchange section,the thermal conductivity of the insulation layer increases and the overall performance of the steam generator decreases.Therefore,the design of the bayonet tube steam generator should use a larger number of heat exchange tubes and inner tube insulation materials with smaller thermal conductivity,and select appropriate annular channel sizes to obtain the optimal JF factor value.