Turbine exhaust catalyst
In a gas turbine installation having an enclosure for passing cooling air therethrough and around the gas turbine, provision is made for a mixing of the cooling air with the exhaust gases being emitted from the gas turbine to thereby reduce the temperature thereof prior to its passing into the exhaust stack, but only after the primary air has passed through a catalyst bed which is disposed in a position over the gas turbine exhaust opening. The shape of the catalyst bed is preferably A-shaped in cross-section to thereby increase the surface area thereof. In this way, the temperature at the catalyst bed is maintained at an elevated level to obtain superior performance while a subsequent mixing of the primary air with the cooling air results in lower temperatures of the gases passing through the exhaust stack.
1. A gas turbine assembly, comprising:
a gas turbine having an inlet for primary air and an exhaust outlet;
a catalyst bed disposed at said outlet for receiving said exhaust gases;
an enclosure disposed around the gas turbine and defining an enclosed space between the gas turbine and said enclosure;
a source of cooling air for passing through said enclosed space and for mixing with exhaust gases after it passes through said catalyst bed; and
an exhaust stack connected to said enclosed space for conducting the flow of the cooling air/exhaust gases mixture to the atmosphere.
2. A gas turbine as set forth in claim 1 wherein said catalyst bed is A-shaped in cross-sectional form, with the apex being orientated downstream.
3. A method of reducing emissions from the exhaust outlet of a gas turbine comprising the steps of:
providing a catalyst bed at the gas turbine exhaust outlet for the passing of gas turbine exhaust gases therethrough;
providing a flow of cooling air to be mixed with said exhaust gases only after it passes through said catalyst bed; and
causing a mixture of cooling air and exhaust gases to flow to an exhaust stack and to be discharged to atmosphere.
4. A method as set forth in claim 3 wherein said catalyst bed is A-shaped in form with its apex orientated in the downstream direction.
5. A gas turbine of the type having an inlet and an outlet, an enclosure for defining an enclosed space between the gas turbine and the enclosure, and a source of cooling air to be circulated through the enclosed space and then mixed with exhaust gases being emitted from the gas turbine outlet and including:
a catalyst disposed at said gas turbine outlet such that said exhaust gases pass first through said catalyst bed and are subsequently mixed with the cooling air and including an exhaust stack for conducting the flow of the cooling air/exhaust gases mixture from the space to the atmosphere.
6. A gas turbine as set forth in claim 5 wherein said exhaust stack includes one or more silencer elements therein.
7. A gas turbine as set forth in claim 5 wherein sad catalyst bed is A-shaped in cross-sectional form, with its apex being orientated downstream.