AN IMPROVED HEAT EXCHANGER TO RAISE THE DEGREE OF SUPERHEAT OF SUPERHEATED COLD REHEAT STEAM (CRH) FROM HIGH PRESSURE TURBINE OF A FAST BREEDER REACTORBY LIVE STEAM FROM STEAM GENERATOR

摘要

An improved Heat Exchanger/live steam reheater (H) to raise the degree of superheat of superheated cold reheat steam (CRH) from high pressure turbine of a fast breeder reactor by live steam from steam generator consists of a bundle of finned U tubes (1) disposed in a cylindrical shell (2) for improving heat transfer coefficient with U-bends of the said U-tube pointing upwards. Two self- compensating nozzles (7, 9) is disposed for allowing shell side fluid (cold reheated steam) from high pressure turbine to enter at topmost point of the said shell (2) through Cold reheat steam inlet (7) and to leave at the bottom most point of the said shell (2) through Hot reheat steam outlet (9) for admission into a lower pressure turbine. A plurality of No-tubes-in-window (NTIW) segmental baffles (12) is disposed for making flow of fluid transverse to axis of tubes to receive heat from tube side fluid. A hemispherical type channel (3) is disposed along with a partition (4) for an inlet and an outlet chambers creating a man-way access (5) for maintenance work. A self sealing cover (14) is attached for closing the said access (5). An impingement plate (13) is attached to shell (2) supported by a swing-like structure (15) attached to dished end (8) which is disposed for protecting U-tubes (1) from impingement effect. The hot fluid that enters as live steam through live steam inlet (10) provided on hemispherical channel (3) enters first legs of U-tubes (1) and leaves as condensate from second legs of U-tubes (1) and exits the hemispherical channel (3) through condensate outlet. The tubes are arranged in a 45 degree square pitch layout for arresting pressure drops, when de-resonating baffles are disposed for increasing acoustic frequency. A tub-shaped tube sheet (6) smoothly interfaces with inner profile of hemispherical head (3) when heat is exchanged between hot fluid flowing through tubes (1) and cold fluid flowing over tubes (1) with minimal flow-induced mechanical and acoustic vibrations and minimal pressure drop.