By means of critical however, - steam generator with superimposed forced circulation

摘要

1,022,838. Steam generators; furnace tube walls. COMBUSTION ENGINEERING Inc. March 19, 1964 [March 25, 1963], No. 11767/64. Headings F4A and F4B. A forced - flow once - through supercritical vapour generator comprises an elongated furnace from which extends a gas pass having side walls parallel to those of the furnace, the walls of the furnace and the gas pass are lined with tubes extending longitudinally and integrally joined together throughout the length of each wall and at the junctions between furnace and gas pass walls, the tubes being connected such that working fluid passes in parallel and in the same direction first through the furnace tubes and then through the gas pass tubes with a recirculation circuit increasing the flow through all the tubes at least at or below a predetermined load. As shown the generator comprises a vertical furnace 10 partitioned by a centre tube wall 16 extending between headers 42, 46 into two chambers each of which may be fired separately, e.g. by tangentially arranged burners 13, 15. Working fluid passes up through the centre wall tubes and then through the furnace and gas pass tubes. Horizontal and vertical portions 26, 28 of a gas pass 24 extend from the furnace, all are of rectangular cross-section, the side walls of the pass being coplanar with those of the furnace. The wall tubes are welded together between webs 66 to form imperforate metallic lining walls for the furnace and gas pass, the width of the web being greater in parts of the gas pass than in the furnace. The tubes of the gas pass may have diametrically opposed rectangular fins, those of adjacent tubes being welded together and the gas pass cased for fluid tightness. The furnace tube walls extend from bottom headers 50 below each furnace outer wall, side walls terminating in upper headers (not shown) connected to header 54, the front wall extending forward to cover part of the gas pass roof and then leading to header 54 and the rear wall extending forward to cover approximately half of the gas pass floor then upward and out of alignment across the gas pass and finally extending back to line the gas pass roof before terminating in header 54. The front tube wall of the vertical gas pass is similarly bent to cover the remaining floor and roof of the gas pass. The front, rear and side walls of the vertical gas pass extend between headers 62 and 70a, the side walls being connected to an intermediate header. The side walls of the horizontal pass extend between inlet header 60 and the intermediate header. Economizer, superheater and reheater sections are located in the gas pass and fluid passes from the economizer 32 through the centre tube wall 16, the outer furnace tube walls and then in the same direction and in parallel through all of the gas pass tube walls before entering the superheater sections. Recirculation through all of the tubes is maintained by a pump 40 connecting header 70a with the inlet header 42 of the centre tube wall.