METHOD AND PLANT FOR CO-GENERATION OF HEAT AND POWER

摘要

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). The method includes, when there is insufficient heat removal from the hot flue gas downstream from the hot flue gas generator (12) but upstream of the steam evaporator (26) as a result of insufficient mass flow of imported steam (110) to the steam superheater (22), to the extent that the hot flue gas temperature downstream of the steam superheater (22) will rise or rises to or above a predetermined limit, quenching steam inside the steam superheater (22) or steam being fed to the steam superheater (22) by injecting boiler feed water or condensate (162) into the steam to produce steam in the steam superheater (22) thereby to increase the removal of heat from the hot flue gas and hence to reduce the hot flue gas temperatures downstream of the steam superheater (22).

主权项

1. A method of operating a combined heat and power plant (CHP plant) which includes a hot flue gas generator 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 (HRSG) which includes a steam evaporator downstream of the hot flue gas generator, and at least one steam superheater between the hot flue gas generator and the steam evaporator, the steam superheater being configured to superheat, during normal operating conditions of the CHP plant, at least steam imported into the HRSG, the method including:
when there is insufficient heat removal from the hot flue gas downstream from the hot flue gas generator but upstream of the steam evaporator as a result of insufficient mass flow of imported steam to the steam superheater, to the extent that the hot flue gas temperature downstream of the steam superheater will rise or rises to or above a predetermined limit, quenching steam inside the steam superheater or steam being fed to the steam superheater by injecting boiler feed water or condensate into said steam to produce steam in the steam superheater thereby to increase the removal of heat from the hot flue gas and hence to reduce the hot flue gas temperatures downstream of the steam superheater.