Patent ID: 12234750

DETAILED DESCRIPTION

The embodiments described herein relate to systems for improving steam integration of a combined cycle power plant for use with post combustion carbon capture. Specifically, the systems described herein use a dual reboiler arrangement, a steam ejector, and a flash drum to facilitate reducing the effects of efficiency penalties and power reduction associated with operating the carbon capture process. More specifically, the dual reboiler arrangement and the steam ejector facilitate increasing the amount of power generated by the steam turbine by reducing an amount of steam extracted from the steam turbine. Moreover, the flash drum facilitates increasing the amount of power generated by the steam turbine by recovering steam used in the carbon capture process, and returning the recovered steam to the steam turbine.

Unless otherwise indicated, approximating language, such as “generally,” “substantially,” and “about,” as used herein indicates that the term so modified may apply to only an approximate degree, as would be recognized by one of ordinary skill in the art, rather than to an absolute or perfect degree. Accordingly, a value modified by a term or terms such as “about,” “approximately,” and “substantially” is not to be limited to the precise value specified. In at least some instances, the approximating language may correspond to the precision of an instrument for measuring the value. Additionally, unless otherwise indicated, the terms “first,” “second,” etc. are used herein merely as labels, and are not intended to impose ordinal, positional, or hierarchical requirements on the items to which these terms refer. Moreover, reference to, for example, a “second” item does not require or preclude the existence of, for example, a “first” or lower-numbered item or a “third” or higher-numbered item.

FIG.1is a schematic illustration of an exemplary combined cycle power plant100. In the exemplary embodiment, power plant100includes a gas turbine102and a steam turbine104. The gas turbine102includes a compressor section106, a combustor108, and a turbine section110coupled together in a serial flow relationship. In operation, combustor108receives air from compressor section106and fuel from a fuel supply and uses the fuel and air to create a fuel-air mixture that is combusted to generate combustion gases. Combustion gases are channeled through the turbine section110and discharged from the turbine section110as an exhaust gas stream112. In the exemplary embodiment, power plant100also includes a steam cycle arrangement170. The steam cycle arrangement170includes a Heat Recovery Steam Generator (HRSG)114and the steam turbine104. In some embodiments, the steam cycle arrangement170may also include other components, including a condenser (not shown) and at least one circulation pump (not shown). HRSG114includes an HRSG inlet116oriented to receive exhaust gas stream112from the gas turbine102, a first HRSG outlet118oriented to discharge a first steam flow120, and a second HRSG outlet138to discharge an exhaust gas flow140. The steam turbine104includes an intermediate pressure steam turbine122that receives the first steam flow120and a low pressure steam turbine124downstream from the intermediate pressure steam turbine122. The steam turbine104discharges a circulation flow126, and in some embodiments, the steam turbine104may include additional pressure steam turbines downstream from the low pressure steam turbine124.

In the exemplary embodiment, power plant100also includes a dual reboiler arrangement128. The dual reboiler arrangement128includes a first reboiler130that receives the circulation flow126and uses heat extracted from the circulation flow126to heat a solvent circulated in a carbon capture arrangement132. The dual reboiler arrangement128further includes a second reboiler134that receives a first portion156of a discharge liquid flow158from the carbon capture arrangement132, preheats the first portion156using heat extracted from an external flow172received from a first external source136, and channels the preheated first portion156into the first reboiler130for use in heating. The external flow172may be liquid or gas. In some embodiments, the first portion156may be preheated using heat extracted from a source internal to power plant100. The first reboiler130and second reboiler134also receive a second portion162of a discharge liquid flow158from the carbon capture arrangement132, and discharge the second portion162to the steam cycle arrangement170. The HRSG114discharges the exhaust gas flow140to the carbon capture arrangement132via the second HRSG outlet138. The exhaust gas flow140includes a plurality of exhaust gases and a carbon dioxide gas. The carbon capture arrangement132separates the plurality of exhaust gases from the carbon dioxide gas. The carbon capture arrangement132then discharges the plurality of exhaust gases via a first carbon capture arrangement outlet180and discharges the carbon dioxide gas via a second carbon capture arrangement outlet182.

During use, the dual reboiler arrangement128facilitates increasing the amount of power generated by the steam turbine104, by reducing an amount of steam extracted from the steam turbine104.

FIG.2is a schematic illustration of an alternative embodiment of a combined cycle power plant200. In the alternate embodiment, power plant200includes a gas turbine102and a steam turbine104. The gas turbine102includes a compressor section106, a combustor108, and a turbine section110coupled together in a serial flow relationship. In operation, combustor108receives air from compressor section106and fuel from a fuel supply and uses the fuel and air to create a fuel-air mixture that is combusted to generate combustion gases. Combustion gases are channeled through the turbine section110and discharged from the turbine section110as an exhaust gas stream112. Power plant200further includes a steam cycle arrangement170. The steam cycle arrangement includes a Heat Recovery Steam Generator (HRSG)114and the steam turbine104. In some embodiments, the steam cycle arrangement170may also include other components, including a condenser (not shown) and at least one circulation pump (not shown). HRSG114includes an HRSG inlet116oriented to receive exhaust gas stream112from the gas turbine102, a first HRSG outlet118oriented to discharge a first steam flow120, a second HRSG outlet138that discharges an exhaust gas flow140, and a third HRSG outlet142that discharges a second steam flow144. The steam turbine104includes a high pressure steam turbine146that receives the second steam flow144, an intermediate pressure steam turbine122downstream from the high pressure steam turbine146that receives the first steam flow120, and a low pressure steam turbine124downstream from the intermediate pressure steam turbine122. The steam turbine104discharges a circulation flow126. In some embodiments, the steam turbine104may include additional pressure steam turbines downstream from the low pressure steam turbine124.

The alternative embodiment shown inFIG.2also includes a steam ejector148that receives the circulation flow126and a fluid flow from a second external source150. The circulation flow126is mixed with the fluid flow from the second external source150prior to a steam mixture154being discharged from the steam ejector148.

In addition, the alternative embodiment includes a dual reboiler arrangement128downstream from the steam ejector148. The dual reboiler arrangement128includes a first reboiler130that receives the steam mixture154discharged from the steam ejector148and uses heat extracted from the steam mixture154to heat a solvent circulated in a carbon capture arrangement132. The dual reboiler arrangement128also includes a second reboiler134that receives a first portion156of a discharge liquid flow158from the carbon capture arrangement132. The second reboiler134preheats the first portion156using heat extracted from an external flow172received from a first external source136, and channels the preheated first portion156into the first reboiler130for use in heating. The external flow172may be liquid or gas. In some embodiments, the first portion156may be preheated using heat extracted from a source internal to power plant100.

The alternative embodiment also includes a flash drum152downstream from the dual reboiler arrangement128. The first reboiler130and second reboiler134receive a second portion162of a discharge liquid flow158from the carbon capture arrangement132and discharge the second portion162to the flash drum152. The flash drum152discharges a recovered steam flow164to the low pressure steam turbine124of the steam turbine104. Moreover, the flash drum152also discharges the second portion162to the steam cycle arrangement170. The HRSG114discharges the exhaust gas flow140to the carbon capture arrangement132via the second HRSG outlet138. The exhaust gas flow140includes a plurality of exhaust gases and a carbon dioxide gas. The carbon capture arrangement132separates the plurality of exhaust gases from the carbon dioxide gas. The carbon capture arrangement132then discharges the plurality of exhaust gases via a first carbon capture arrangement outlet180and discharges the carbon dioxide gas via a second carbon capture arrangement outlet182.

During use, the dual reboiler arrangement128, the steam ejector148, and the flash drum152facilitate increasing the amount of power generated by the steam turbine104. The dual reboiler arrangement128and the steam ejector148facilitate this power increase by reducing an amount of steam extracted from the steam turbine104. The flash drum152facilitates this power increase by recovering steam used by the carbon capture arrangement132and returning the recovered steam to the steam turbine104.

Further aspects of the invention are provided by the subject matter of the following clauses:

1. A combined cycle (CC) power plant comprising: a steam cycle arrangement comprising a heat recovery steam generator (HRSG) and a steam turbine; said HRSG comprising an HRSG inlet oriented to receive exhaust gases from a gas turbine, and a first HRSG outlet oriented to discharge a first steam flow; and a dual reboiler arrangement comprising a first reboiler and a second reboiler, said first reboiler coupled in flow communication with said first HRSG outlet, said first reboiler configured to receive a circulation flow discharged from the steam turbine and use heat extracted from the circulation flow to heat a solvent circulated by a carbon capture arrangement, said second reboiler oriented to receive a first portion of a discharge liquid flow from the carbon capture arrangement, said second reboiler configured to preheat the first portion using heat extracted from an external flow received from a first external source, and channel the preheated first portion into said first reboiler for use in heating.

2. The CC power plant according to clause1, wherein said second reboiler is in flow communication with the first external source including at least one of a second HRSG outlet, a treatment hot water source, and a waste heat source.

3. The CC power plant according to any of the preceding clauses, wherein said first reboiler is further configured to receive a second portion of the discharge liquid flow from the carbon capture arrangement.

4. The CC power plant according to any of the preceding clauses, further comprising a steam ejector coupled in flow communication between said first HRSG outlet and said first reboiler, said steam ejector configured to receive a second external source fluid flow, and mix the circulation flow and the second external source fluid flow.

5. The CC power plant according to any of the preceding clauses, further comprising a flash drum coupled in downstream flow communication with said first reboiler, said flash drum configured to recover excess steam from said first reboiler and discharge the recovered excess steam to said steam cycle arrangement.

6. The CC power plant according to any of the preceding clauses, wherein said flash drum is further coupled in downstream flow communication with said second reboiler and is configured to include a portion of recovered excess steam from said second reboiler in the discharge to said steam cycle arrangement.

7. The CC power plant according to any of the preceding clauses, further comprising said carbon capture arrangement configured to capture carbon-based emissions from the gas turbine.

8. A system for improving steam integration of a combined cycle (CC) power plant, the system comprising: a steam cycle arrangement comprising a heat recovery steam generator (HRSG) and a steam turbine; said HRSG comprising an HRSG inlet oriented to receive exhaust gases from a gas turbine, and a first HRSG outlet oriented to discharge a first steam flow; a dual reboiler arrangement comprising a first reboiler and a second reboiler, said first reboiler coupled in flow communication with said first HRSG outlet, said first reboiler configured to receive a circulation flow discharged from the steam turbine and use heat extracted from the circulation flow to heat a solvent circulated by a carbon capture arrangement, said second reboiler oriented to receive a first portion of a discharge liquid flow from the carbon capture arrangement, said second reboiler configured to preheat the first portion using heat extracted from an external flow received from a first external source, and channel the preheated first portion into said first reboiler for use in heating; a steam ejector coupled in flow communication between said first HRSG outlet and said first reboiler, said steam ejector configured to receive a second external source fluid flow, and mix the circulation flow and the second external source fluid flow; and a flash drum coupled in downstream flow communication with said first reboiler, said flash drum configured to recover excess steam from said first reboiler and discharge a portion of the recovered excess steam to said steam cycle arrangement.

9. The system according to the previous clause, wherein the carbon capture arrangement is configured to capture carbon-based emissions from the gas turbine.

10. The system according to any of the preceding clauses, wherein said first reboiler is further configured to receive a second portion of the discharge liquid flow from the carbon capture arrangement and heat the second portion.

At least one of the technical solutions provided by this system to the technical problems may include: (i) reduced efficiency penalties of a power plant system associated with operating a carbon capture process; (ii) increased power production of a power plant system; (iii) reduced amount of steam extracted from a steam turbine of a power plant system; and (iv) increased amount of steam recovered from a carbon capture process and returned to a steam turbine of a power plant system.

The methods described herein may be implemented using a power plant system, wherein the technical effects may be achieved by performing at least one of the following steps: a) receiving exhaust gases from a gas turbine using a heat recovery steam generator (HRSG); b) receiving steam from a steam turbine or from a steam ejector downstream from the steam turbine using a dual reboiler arrangement, the dual reboiler arrangement including a first reboiler and a second reboiler; c) using heat extracted from the steam received by the dual reboiler arrangement to heat a solvent circulated by a carbon capture arrangement; and d) recovering excess steam from the carbon capture arrangement using a flash drum.

The above description is meant to be exemplary only, and one skilled in the art will recognize that changes may be made to the embodiments described without departing from the scope of the invention disclosed. For example, the process steps described herein may be modified in duration, temperature, or time between cycles, for example. Still other modifications, which fall within the scope of the present invention, will be apparent to those skilled in the art, in light of a review of this disclosure, and such modifications are intended to fall within the appended claims.

Exemplary embodiments of a combined cycle power plant are described above in detail. The methods of improving steam integration are not limited to the specific embodiments described herein, but rather, steps of the methods may be utilized independently and separately from other steps described herein. For example, the methods described herein are not limited to practice with combined cycle power plants as described herein. Rather, the exemplary embodiment can be implemented and utilized in connection with many other applications.

Although specific features of various embodiments of the invention may be shown in some drawings and not in others, this is for convenience only. Moreover, references to “one embodiment” in the above description are not intended to be interpreted as excluding the existence of additional embodiments that also incorporate the recited features. In accordance with the principles of the invention, any feature of a drawing may be referenced and/or claimed in combination with any feature of any other drawing.

While the invention has been described in terms of various specific embodiments, those skilled in the art will recognize that the invention can be practiced with modification within the spirit and scope of the claims.

The patent claims at the end of this document are not intended to be construed under 35 U.S.C. § 112(f) unless traditional means-plus-function language is expressly recited, such as “means for” or “step for” language being expressly recited in the claim(s).

This written description uses examples to disclose the disclosure, including the best mode, and also to enable any person skilled in the art to practice the disclosure, including making and using any devices or systems and performing any incorporated methods. The patentable scope of the disclosure is defined by the claims, and may include other examples that occur to those skilled in the art. Such other examples are intended to be within the scope of the claims if they have structural elements that do not differ from the literal language of the claims, or if they include equivalent structural elements with insubstantial differences from the literal language of the claims.