Abstract: A method of operating a combined heat and power plant (10) (CHP plant) includes generating hot flue gas in a hot flue gas generator (12) and cooling the hot flue gas in a sequence of cooling steps to recover heat and to generate steam in a heat recovery steam generator (16) (HRSG). The HRSG (16) includes an HP steam evaporator (26) downstream of the hot flue gas generator (12) in which HP steam is generated and in which the hot flue gas is cooled, at least one HP steam superheater (20, 22) between the hot flue gas generator (12) and the HP steam evaporator (26) in which at least HP steam from the HP steam evaporator is superheated and in which the hot flue gas is cooled, and an MP steam superheater (24) upstream of the HP steam evaporator (26) in which MP steam is superheated by the hot flue gas and in which hot flue gas is cooled.

Abstract: A method of operating a combined heat and power plant includes, when there is insufficient heat removal from a hot flue gas downstream from a hot flue gas generator but upstream of a steam evaporator, as a result of insufficient mass flow of imported steam to a steam superheater, to prevent the hot flue gas temperature downstream of the steam superheater from rising to or above a predetermined limit, quenching steam inside the steam superheater or quenching steam being fed to the steam superheater by injecting boiler feed water or condensate into the steam to produce steam in the steam superheater. The quenching increases the removal of heat from the hot flue gas and reduces the hot flue gas temperature downstream of the steam superheater to ensure that the hot flue gas temperature downstream of the steam superheater does not rise to or above the predetermined limit.

Abstract: A method of operating a combined heat and power plant (10) (CHP plant) includes generating hot flue gas and cooling the hot flue gas in a sequence of cooling steps to recover heat and to generate steam in a heat recovery steam generator (16) (HRSG). The HRSG (16) includes an LP steam evaporator (36) designed to generate steam at least over a pressure range of from 2 bar(g) to 18 bar(g) so that either LP steam or MP steam can selectively be generated by the LP steam generator (36), thereby to cool the hot flue gas, and an MP steam superheater (24) upstream of the LP steam evaporator (36) to superheat MP steam in heat exchange with the hot flue gas thereby to cool the hot flue gas.

Abstract: A method of operating a combined heat and power plant (10) (CHP plant) is provided. The CHP plant (10) includes a hot flue gas generator (12) generating hot flue gas which is then cooled in a sequence of cooling steps to recover heat and to generate steam in a heat recovery steam generator (16) (HRSG). The HRSG (16) includes a steam evaporator (26) downstream of the hot flue gas generator (12), and at least one steam superheater (22) between the hot flue gas generator (12) and the steam evaporator (26). The steam superheater (22) is configured to superheat, during normal operating conditions of the CHP plant (10), at least steam (110) imported into the HRSG (16).

Abstract: A method of operating a combined heat and power plant (10) (CHP plant) includes generating hot flue gas and cooling the hot flue gas in a sequence of cooling steps to recover heat and to generate steam in a heat recovery steam generator (16) (HRSG). The HRSG (16) includes an LP steam evaporator (36) designed to generate steam at least over a pressure range of from 2 bar(g) to 18 bar(g) so that either LP steam or MP steam can selectively be generated by the LP steam generator (36), thereby to cool the hot flue gas, and an MP steam superheater (24) upstream of the LP steam evaporator (36) to superheat MP steam in heat exchange with the hot flue gas thereby to cool the hot flue gas.

Abstract: A method of operating a combined heat and power plant (10) (CHP plant) includes generating hot flue gas in a hot flue gas generator (12) and cooling the hot flue gas in a sequence of cooling steps to recover heat and to generate steam in a heat recovery steam generator (16) (HRSG). The HRSG (16) includes an HP steam evaporator (26) downstream of the hot flue gas generator (12) in which HP steam is generated and in which the hot flue gas is cooled, at least one HP steam superheater (20, 22) between the hot flue gas generator (12) and the HP steam evaporator (26) in which at least HP steam from the HP steam evaporator is superheated and in which the hot flue gas is cooled, and an MP steam superheater (24) upstream of the HP steam evaporator (26) in which MP steam is superheated by the hot flue gas and in which hot flue gas is cooled.