A METHOD OF CONTROLLING A PFBC PLANT IN THE EVENT OF OPERATIONAL DISTURBANCE IN THE GAS TURBINE UNIT AND A PFBC PLANT WITH EQUIPMENT FOR SUCH CONTROL

摘要

The invention relates to a method of controlling a PFBC power plant in the event of an operational disturbance affecting a turbine unit driven by the plant, for example a load drop out, said plant comprising a bed vessel (12) enclosed within a pressure vessel (10) and surrounded by compressed combustion air, said bed vessel containing a bed (22) of fluidizable particulate material, and a gas turbine-compressor unit (34,38,48) driven by combustion gases from the bed vessel (12). In a hot gas conduit (32) between the bed vessel (12) and a turbine (34) there is a first cut-off valve (54), and in a conduit (50) between a compressor (48) and the bed vessel (12) there is a second cut-off valve (58). Between said conduits (32,50) there is a short-circuit conduit (62) with a third cut-off valve (64). In case of an operational disturbance as mentioned above, the turbine-compressor unit (34,38,48) is cut off from the bed vessel (12) and the pressure vessel (10), respectively, by shutting off said first and second valves (54,58) in the conduits (32,50) between the bed vessel (12) and the turbine (34) and between the compressor (48) and the pressure vessel (10), respectively. At the same time, the bypass valve (64) in the short-circuit conduit (62) is opened. In the event of a lengthy operational disturbance requiring shutdown of the power plant, the combustion gases in the bed vessel (12) are dumped into the atmosphere via a dump conduit (68) and a dump valve (72). When dumping the combustion gases, cooling water is injected into the dump conduit (68) upstream of the dump valve (72) so that the gases are cooled before reaching the dump valve (72). The invention also relates to a power plant having a device (70) for injection of cooling water into a conduit (68) upstream of a dump valve (72) for cooling the hot combustion gases from the bed vessel (12) before they reach the dump valve (72).