APPARATUS OF REGIULATING THE STEAM TEMPERATURE FROM HEAT RECOVERY STEAM GENERATOR BY MEANS OF WATER OF VARIABLE DEGREE OF SUBCOOLING,

摘要

The hot exhaust gas line from the gas turbine is connected to the Heat Recovery Steam Generator (HRSG) system for absorbing the heat available in the flue gas. Generally the first section to receive the hot gas in the HRSG is the super heater system. The super heater system may comprise one or more superheaters formed of a plurality of tubes; a de super heater system consisting of a single or plurality de super heaters; one or more evaporators; and one or more water heating sections. Further, one or more stages of fuel burning equipment(s) in the gas path may be provided to raise the output from the HRSG. The gas turbine exhaust parameters are subjected to several variations due to ambient and operating conditions and hence the absorption in individual sections also vary at different operating conditions. Particularly in the superheater, a higher heat absorption leads to higher than required steam temperatures and is not desirable. Hence a method of maintaining the steam temperature within an acceptable range is necessary. In accordance with the present invention, a temperature maintenance apparatus enabled to utilize water at varying degree of subcooling from outlet or intermediate locations in the economiser in the Heat recovery steam generator (HRSG) is provided. The apparatus is adaptable for operation of the super heater system for regulating the outlet steam temperature in an acceptable range resulting in operational improvements for example, a lower flue gas temperature in an acceptable range resulting in operational improvements for example, a lower flue gas temperature at the HRSG outlet a lower fuel consumption in the HRSG and an enhanced controllability of the Steam temperature. The apparatus employs super heaters for steam heating and allows the temperature maintenance apparatus to always consume significant quantity of spray water in the normal operating condition.[IN-KOL-2010-00051A]