Patent Application
20130199150
The subject matter disclosed herein relates to combined cycle systems, and more particularly to steam generation and injection into such a system.
As gas turbine systems take on more base-load power generation, a higher fluctuation of electricity load demand is expected and, as a result, more gas turbine power plants are forced to run at part load conditions during off-peak hours. The problems associated with the part load operation are that increased gas turbine turndown ratios typically result in higher NOx emission, as well as turbine fuel efficiency deteriorating as the load is reduced.
According to one aspect of the invention, a steam injection assembly for a combined cycle system includes a heat recovery system having at least one superheater configured to generate a steam supply. Also included is a gas turbine system having an inlet and a compressor, wherein the inlet receives an air supply and the steam supply for combined injection into the compressor.
According to another aspect of the invention, a steam injection assembly for a combined cycle system includes a gas turbine system having a compressor, a combustor, and a turbine. Also included is a heat recovery system configured to receive and process heat exhaust from the gas turbine system. Further included is at least one superheater disposed within the heat recovery system and configured to generate a steam supply. Yet further included is at least one valve operably connected to the at least one superheater for controlling the flow rate and the temperature of the steam supply. Also included is an inlet disposed proximate the compressor and configured to receive an air supply and the steam supply for injection to the compressor.
According to yet another aspect of the invention, a steam injection assembly for a combined cycle system includes a gas turbine system having a compressor, a combustor and a turbine. Also included is a heat recovery system configured to produce steam and distribute a steam supply out of the heat recovery system. Further included is an inlet assembly disposed proximate the compressor, wherein the inlet assembly receives and mixes an air supply and the steam supply prior to injection into the compressor.
These and other advantages and features will become more apparent from the following description taken in conjunction with the drawings.
The subject matter, which is regarded as the invention, is particularly pointed out and distinctly claimed in the claims at the conclusion of the specification. The foregoing and other features and advantages of the invention are apparent from the following detailed description taken in conjunction with the accompanying drawings in which:
The detailed description explains embodiments of the invention, together with advantages and features, by way of example with reference to the drawings.
Referring to
In operation, air flows into the compressor 12 and is compressed into a high pressure gas. The high pressure gas is supplied to the combustor assembly 14 and mixed with fuel, for example process gas and/or synthetic gas (syngas). The fuel/air or combustible mixture ignite to form a high pressure, high temperature combustion gas stream of approximately 538 degrees Celsius (° C.) to 1593° C. (1000 degrees Fahrenheit (° F.) to 2900° F.). Alternatively, the combustor assembly 14 can combust fuels that include, but are not limited to, natural gas and/or fuel oil. In any event, the combustor assembly 14 channels the combustion gas stream to the turbine 16 which converts thermal energy to mechanical, rotational energy which is capable of driving a power source, such as a generator 20.
Referring now to
Although the heat recovery system 30 has been described as an assembly having a plurality of superheaters, it is to be appreciated that the generation of heat, and hence steam, may be derived from an alternative heat recovery system 30, such as an auxiliary boiler or process steam source.
A steam supply 60 exits the heat recovery system 30 and is comprised of one or more of the first steam 42, second steam 44 and third steam 46. As described above, each steam 42, 44 and 46 are of distinct pressures, and in one illustrative arrangement, the first steam 42 has a relatively high pressure, with respect to the second steam 44 and the third steam 46, while the second steam 44 has an intermediate pressure, specifically having a pressure less than the first steam 42, but greater than the third steam 46, which is of a relatively low pressure. The steam supply 60 may selectively be comprised of only one of the steams 42, 44 or 46, or alternatively, may be selectively comprised of any combination of the steams 42, 44 or 46. While the steams and their relative pressures have been described and illustrated in a particular order, it is to be appreciated that the actual number of superheaters and steams may be modified, as well as their relative pressures to one another.
Referring again to
The steam supply 60 is then routed through a steam supply line 90, which terminates at one end proximate an inlet assembly 100 of the gas turbine system 11. The inlet assembly 100 is configured to receive an air supply 102 that is at an ambient condition having a temperature lower relative to that of the steam supply 60. The steam supply 60 mixes with the air supply 102 in the inlet assembly 100 in preparation for injection to the gas turbine system 11, and more specifically the compressor 12.
Referring to
Advantageously, the combined cycle system 10 mixes the steam supply 60 with the air supply 102 prior to injection into the gas turbine system 11, resulting in an increased temperature and humidity of the air supply 102 entering the gas turbine system 11, and specifically the compressor 12. Such mixing may occur upstream of the compressor 12, or in close proximity thereto. The heat energy addition to the air supply 102 allows the compressor 12 to run at part load conditions with higher volumetric flow rates that it would be at ambient conditions, which leads to higher fuel efficiency. Additionally, added moisture content in the air supply 102 assists in NOx reduction. The NOx reduction at the part load range also may assist to reduce the demand on a Selective Catalytic Reactor (SCR) or potential removal of the SCR, based on application requirements.
While the invention has been described in detail in connection with only a limited number of embodiments, it should be readily understood that the invention is not limited to such disclosed embodiments. Rather, the invention can be modified to incorporate any number of variations, alterations, substitutions or equivalent arrangements not heretofore described, but which are commensurate with the spirit and scope of the invention. Additionally, while various embodiments of the invention have been described, it is to be understood that aspects of the invention may include only some of the described embodiments. Accordingly, the invention is not to be seen as limited by the foregoing description, but is only limited by the scope of the appended claims.
