Patent Application
20140069078
The present application and the resultant patent relate generally to gas turbine engines and more particularly relate to a combined cycle system using one or more water turbines for supplemental power generation and/or other uses from otherwise wasted energy.
Generally described, a combined cycle system uses a combination of a gas turbine and a steam turbine to produce electrical power or otherwise drive a load. Specifically, a gas turbine cycle may be operatively combined with a steam turbine cycle by way of a heat recovery steam generator and the like. The heat recovery steam generator is a heat exchanger that allows feed water for the steam generation process to be heated by the hot combustion gases of the gas turbine exhaust. The primary efficiency of the combined cycle system arrangement is the utilization of the otherwise “wasted” heat of the gas turbine engine exhaust. Specifically, the efficiency of the heat recovery steam generator focuses on the heat transfer between the gas turbine combustion gases (“the hot side”) and the feed water and the steam (“the cold side”). As much of the heat and pressure as possible of the gas turbine combustion gases thus may provide useful work.
Although a combined cycle system is efficient, there are numerous types of parasitic losses involved in overall system operation. For example, high pressure water from the heat recovery steam generator may be used to heat the flow of fuel to the gas turbine engine so as to improve overall turbine performance. This high pressure water, however, generally is dumped directly to the condenser after heating the fuel without utilizing all of the pressure energy therein.
In addition to parasitic loses, a combined cycle system also may have routine operating losses. These losses may be due to equipment design requirements, pressure budgets, and the like. For example, high pressure water in the heat recovery steam generator may be expanded across a number of valves without accomplishing useful work when flowing into a low pressure drum or elsewhere at normal operating flows and pressures.
There is thus a desire for an improved combined cycle power plant with reduced parasitic loses and operating losses. Preferably, otherwise wasted high pressure and/or heat may provide useful work for supplemental power generation and/or other uses.
The present application and the resultant patent thus provide a combined cycle system with a flow of feed water therein. The combined cycle system may include a gas turbine, a steam turbine, a heat exchanger with the flow of feed water flowing therethrough, an expansion source for expanding the flow of feed water, and a supplemental power generation system positioned between the heat exchanger and the expansion source and driven by the flow of feed water.
The present application and the resultant patent further provide a heat recovery steam generator with a flow of feed water therein. The heat recovery steam generator may include an economizer, a drum, and a water turbine positioned between the economizer and the drum.
The present application and the resultant patent further provide a combined cycle system with a flow of feed water therein. The combined cycle system may include a gas turbine, a performance heater with the flow of feed water flowing therethrough, a steam turbine with a condenser, and a water turbine positioned downstream of the performance heater and driven by the flow of feed water.
These and other features and improvements of the present application and the resultant patent will become apparent to one of ordinary skill in the art upon review of the following detailed description when taken in conjunction with the several drawings and the appended claims.
Referring now to the drawings, in which like numerals refer to like elements throughout the several views,
The combined cycle system 10 also includes a steam turbine 30. The steam turbine 30 may include a high pressure section 32, an intermediate pressure section 34, and one or more low pressure sections 36 with multiple steam admission points at different pressures. The low pressure section 36 may exhaust into a condenser 38. One or multiple shafts 26 may be used herein. Other configurations and other components also may be used herein.
The combined cycle system 10 also may include a heat recovery steam generator 40. The heat recovery steam generator 40 may include a low pressure section 42, an intermediate pressure section 44, and a high pressure section 46. Each section 42, 44, 46 generally includes one or more drums, economizers, evaporators, and/or superheaters. In this example and in addition to other components, the low pressure section 42 may include a low pressure drum 48 and a low pressure economizer 50. Likewise, the intermediate pressure section 44 may include an intermediate pressure drum 52 and an intermediate pressure economizer 54.
Feed water from the condenser 38 may be fed to the heat recovery steam generator 40 via a condensate pump 56. The flow of feed water may be expanded within the low pressure drum 48 and then pass through the sections 42, 44, 46 of the heat recovery steam generator 40 so as to exchange heat with the flow of combustion gases 22 from the gas turbine engine 12. The steam produced in the heat recovery steam generator 40 then may be used to drive the steam turbine 30. Likewise, hot, high pressure water produced in the heat recovery steam generator 40 may be used in a performance heater 58 to heat the incoming flow of fuel 20 to the combustor 18. The water used in the performance heater 58 generally is dumped directly to the condenser 38 after use. This description of the combined cycle system 10 is for the purpose of example only. Many other components and other configurations may be used herein.
Instead of flowing the feed water from the lower pressure economizer 140 directly to the low pressure drum 130 for expansion therein as is described above, at least a portion of the flow of feed water may be directed to a supplemental power generation system 150. As will be described in more detail below, the supplemental power generation system 150 may include a water turbine 160. The water turbine 160 may be in communication with a by-pass line 170 from the low pressure economizer 140. The flow of feed water then may flow into a splitter 180 with a first portion of the flow heading towards the water turbine 160 via a turbine line 190 and a second portion of the flow heading towards the low pressure drum 130 via a makeup line 200. The turbine line 190 may include one or more flow control valves 210 and/or inlet valves 220. The makeup line 200 may include one or more level control valves 230 and a level controller 240. After passing through the water turbine 160, the first portion of the flow may continue to the low pressure drum 130 via a return line 250. Additional inlet valves 220 and the like may be used herein. Other components and other configurations may be used herein.
The supplemental power generation system 150 thus uses the pressure of the flow of feed water from the low pressure economizer 145 to drive the water turbine 150. The otherwise wasted pressure in the flow thus drives the induction generator 300 to produce supplemental power or other types of useful work. Multiple supplemental power generation systems 150 and multiple water turbines 160 may be used herein in varying locations.
The supplemental power generation systems described herein thus utilize otherwise wasted high pressure flows so as to produce supplemental power and/or otherwise useful work in a combined cycle system. The positioning of the water turbine 160 downstream of the low pressure economizer 140, the intermediate pressure economizer 350, and/or the performance pump 390 are for the purpose of example only. The water turbine 160 may be positioned across any pressure drop in any location so as to recover energy therein (although locations with large water flow rates and high pressures may be preferred). The supplemental power generation systems thus improve overall system efficiency and output.
It should be apparent that the foregoing relates only to certain embodiments of the present application and the resultant patent. Numerous changes and modifications may be made herein by one of ordinary skill in the art without departing from the general spirit and scope of the invention as defined by the following claims and the equivalents thereof.
