潮汐能真空泵工作特性与抽气能力

Tidal energy vacuum pump:working performance and suction capacity

理论分析和模拟实验表明连续式潮汐能虹吸真空泵具有可靠的工作原理和工业化利用价值。利用3.5m高落差可在7.5kPa(绝压)抽气压力下达到大于2×10-5 kg.(kg海水)-1的抽气能力,用作冷却介质的海水可先用于真空抽气,3070t.h-1海水流量即可满足900MW压水堆核电站汽轮机凝汽器7.5kPa(绝压)下61.4kg.h-1真空抽气负荷,取代额定功率132kW的机械真空泵。抽气能力随真空抽气压力上升而增加,其上限受气液两相动量传递速率或气体最大动量流率限制,应使海水流速大于该极值点的对应值以避免虹吸中断。光滑管且无局部阻力损失的理想工况抽气效率可达0.6,但随局部阻力损失增加而锐降,设计和应用要尽量避免管路阻力元件对气液两相流造成的局部阻力损失,使潮汐能真空泵的工作点位于高效区。

Continuous siphon vacuum pump driven by tidal energy（TEVP）,with its experimentally-proved suction capacity over 2×10-5 kg gas·（kg sea water）-1 employing 3.5 m tidal height margin under 7.5 kPa（abs.）suction pressure,showed the potential of industrial application based on reliable theoretical principles.Sea water could be used as working fluid for vacuum suction prior to performing as cooling medium for a coastal plant.In a 900 MW pressurized water reactor nuclear power station,a 132 kW mechanical vacuum pump with 61.4 kg·h-1 of suction capacity under the pressure of 7.5 kPa（abs.）was expected to be replaced by a TEVP employing sea water with a flow rate of 3070 t·h-1.The suction capacity would be increased along with the increase of suction pressure,which was constrained by the rate of momentum transfer between gas and liquid phases,or the maximum of momentum flow rate of the gas phase.In order to avoid siphon break-off,the velocity of sea water in the siphon pipe should be greater than the velocity under the maximum momentum flow rate of the gas phase.The ideal suction efficiency could reach 0.6 when involving a smooth pipe model for calculation and ignoring local flow resistance,but it would sharply decrease taking into consideration the local flow resistance loss caused by valves and other pipe fittings.Therefore it was a basic principle to avoid flow resistance caused by pipe fittings regarding the gas/liquid two-phase flow for a TEVP to ensure its performance in high efficiency region.