EVAPORATION CYCLE OF A NATURAL CIRCULATION STEAM GENERATOR IN CONNECTION WITH A VERTICAL DUCT FOR UPWARD GAS FLOW

摘要

The present invention relates to an evaporation cycle (10) of a natural circulation steam generator associated with a vertical duct (12) for an upward gas flow (14), the evaporation cycle comprising a steam drum (16); And an evaporator (20) in flow communication with the downcomer tube and having a first evaporation section (28) and a second evaporation section (30) connected in parallel with the first evaporation section and disposed at a higher level than the first evaporation section, Each of the evaporation sections including a plurality of parallel connected evaporation tubes 32,42 and having a substantially horizontal passage 34 or a plurality of substantially parallel passages 44,44 The evaporator (20); And an upward tube (22) in flow communication with the evaporator. According to the invention, an evaporator cycle is not associated with an external driving force source other than the heat originating from the gas flow to assist in the flow of water in the evaporator, and the evaporator is connected to the first and second evaporation sections Includes a vertically disposed exit manifold (40) for carrying steam and water towards the upward tube, the outlet manifold including a lower portion (38) and an upper portion (48) above the lower portion. Moreover, the first evaporation section is in direct fluid communication with the lower portion, and the second evaporation section is in direct fluid communication with the upper portion.;