Moisture separator reheater with thermodynamically enhanced means for

Abstract

A Moisture Separator Reheater (MSR) has a plurality of tube bundles which receive high-pressure saturated (tubeside) steam therein. Steam to be reheated (shellside steam) is passed in heat-exchange relationship with the tubes of the first and second reheater tube bundles after first being dried by the panels of a moisture separator. It emerges from the shell of the reheater dried and heated. In the reheater tube bundles saturated steam at temperatures and pressures substantially higher than the shellside steam transfers heat to the shellside steam by condensation within the tubes. The steam in the second stage tube bundle is at a temperature and pressure that is substantially higher than that of the steam in the first stage tube bundle and is heating shellside steam at a higher temperature than the shellside inlet steam to the first stage tube bundle. A greater quantity of tubeside steam than is theoretically necessary is passed through the tube bundles. This excess steam causes scavenging of the tube bundle to substantially eliminate condensate subcooling and related instabilities. Scavenging steam is provided to the first stage tube bundle with essentially no thermodynamic loss by passing the exhausted scavenging steam from the second stage tube bundle through a high differential pressure (.DELTA.P) thermocompressor where it is isentropically expanded. It then entrains a higher rate of exhausted scavenging steam from the first stage tube bundle. The mixed discharge from the thermocompressor is then fed to the inlet of the first stage tube bundle, resulting in a high rate of scavenging steam therein. Minimal thermodynamic loss is achieved since the first stage scavenging steam is reused to continually scavenge the first stage tube bundle, rather than being exhausted to a lower energy point in the system, as is conventionally done, as for example to a feedwater heater.