JP2006514209A - Wet air turbine cycle comprising recovering carbon dioxide - Google Patents

Abstract

Carbon dioxide 152 is removed after the compressor 130 which compresses the mixture of compressed air 132 and the recirculated exhaust gas 118 ′ from the gas turbine 120. The gas 136 from which carbon dioxide has been removed is humidified (180, 114) and supplied to the combustor 110.

Description

  The field of the invention is to recover carbon dioxide, in particular to recover carbon dioxide from a humid air turbine cycle.

  Combustion gases, particularly flue gas from gas turbines, contain significant amounts of carbon dioxide, which is a known greenhouse gas. Therefore, separating and / or sequestering carbon dioxide from the combustion process has received considerable attention over the last decade. There are also many forms and methods known in the art for removing carbon dioxide from flue gas.

  For example, carbon dioxide is disclosed in US Pat. No. 4,130,403 to Cooley et al., US Pat. No. 4,639,257 to Duckett et al., Or US Pat. No. 5,233,837 to Callahan. One or more membranes as described in can be used to remove from various gas streams. Membrane processes generally exhibit a relatively high selectivity for specific gas components. In addition, membrane processes can generally operate without energy consumption cycling (eg, heating and / or cooling requirements often required for solvent-based carbon dioxide removal). However, depending on the feed gas components in particular, the membrane lifetime is shorter than the desired lifetime, or the feed gas requires pretreatment before contacting the membrane. In addition, membrane systems generally operate at relatively high pressure differentials, thereby requiring a blower or other pressure raising device for the low pressure feed gas, otherwise such a low pressure feed gas causes the membrane system to Disable.

  Alternatively, carbon dioxide gas can be removed using physical or chemical solvents, and numerous process forms of solvents are known in the art. A physical solvent process is particularly advantageous when the acidic gas partial pressure in the feed gas is relatively high. Thus, all or almost all physical solvents show only limited utility for removing carbon dioxide from flue gas, which gas has a relatively low carbon dioxide content, especially in flue gas The case is generally at atmospheric pressure.

  For the circulation problems associated with the use of physical solvents, chemical solvents are used to purify the feed gas, which can be regenerated downstream to recover carbon dioxide. By purifying the gas using a chemical solvent, it is generally possible to remove carbon dioxide from the feed gas at a relatively low pressure. However, such methods are often energy intensive and at the same time costly, with frequent problems of corrosion and solvent degradation (eg, US Pat. No. 2,065,112, US Pat. No. 2,399). No. 142, U.S. Pat. No. 2,377,966, U.S. Pat. No. 4,477,419, U.S. Pat. No. 3,137,654). Furthermore, when the partial pressure of carbon dioxide in the feed gas (e.g., exhaust gas from a gas turbine operated by a relatively large amount of excess air and exhaust gas from a humid air turbine (HAT) cycle) decreases, The scale and power consumed by the blower generally increases significantly to overcome the pressure drop in the recovery unit.

  Accordingly, various carbon dioxide removal forms and processes are known in the art, but all or nearly all of them, especially when the partial pressure and / or concentration of carbon dioxide in the feed gas is relatively low Has one or more disadvantages.

  Therefore, there is a need to further provide improved forms and methods for recovering carbon dioxide from various gases, particularly those having a relatively low carbon dioxide partial pressure.

  The present invention is directed to a method and form of carbon dioxide removal from flue gas, wherein at least a portion of the flue gas is compressed to a higher pressure, thereby improving the efficiency of carbon dioxide removal.

  In one aspect of the present inventive subject matter, a plant comprises a combustor that combusts fuel in the presence of heated humid air and produces exhaust expanded with an expander. A compressor (operably coupled to the expander) compresses air and at least a portion of the exhaust from the expander to create a compressed gas mixture and removes carbon dioxide from the gas in the acid gas removal unit Then, the humidifier humidifies the compressed mixed gas from which carbon dioxide has been removed so as to generate heated humid air.

  In such plants, it is further particularly preferred that the heated humid air is heated using exhaust as a heat source, and that the humidifier uses water heated by at least one of the compressed gas mixture and the exhaust gas. It is. While various methods of acid gas removal are contemplated, preferred acid gas removal units comprise a membrane unit or use a solvent (eg, an amine-based solvent). In another embodiment, a portion of the compressed gas mixture can also be supplied to the combustor, where the cooler provides cooling to the expanded exhaust, thereby condensing water from the expanded exhaust. Is done.

  If the acid gas removal unit is equipped with an autorefrigeration unit, the autocooling unit removes carbon dioxide from the first portion of the compressed gas mixture and the humidifier humidifies the second portion of the compressed gas mixture. Thus, it is contemplated to create heated humid air.

  Thus, in general, a plant can include a turbine combustor, particularly a humid air turbine combustor that receives humid air from which fuel and carbon dioxide have been removed, and after a portion of the carbon dioxide has been removed for recovery, It is contemplated that at least a portion of the humid air from which carbon dioxide has been removed is created from the exhaust gas of the humid air turbine combustor. Carbon dioxide in this form is advantageously extracted from carbon dioxide-containing air (a mixture of fresh air and recycled flue gas containing carbon dioxide) using a membrane unit or solvent. From another perspective, a contemplated plant in which carbon dioxide is removed from the exhaust gas of a turbine combustor thus compresses air and at least a portion of the exhaust gas (recycled gas) to produce a compressed mixed gas A carbon dioxide can be removed from the compressed gas mixture in the acid gas removal unit.

  Various objects, features, aspects and advantages of the present invention will become more apparent from the following detailed description of preferred embodiments of the invention, along with the accompanying drawings in which like numerals represent like components.

  The inventor has recovered the carbon dioxide contained in the exhaust gas of the gas turbine by the pressure generated by recycling at least a portion of the exhaust gas and returning it to the compressor, thereby increasing the partial pressure of carbon dioxide in the compressed gas. Thus, it has been discovered that appropriate acid gas removal techniques can be used to facilitate the removal of carbon dioxide (eg, using a physical or chemical solvent, a specific membrane of carbon dioxide, or an automated cooling process).

  In a particularly preferred form as represented in FIG. 1, an exemplary plant 100 includes a humid air turbine cycle for power generation and expanded exhaust to recover carbon dioxide at elevated pressure. At least a portion of which is recycled and returned to the compressor. More specifically, combustor 110 receives fuel 112 and heated humid air 114 ′ and produces exhaust 116, which is then expanded in expander 120. The heat in the expanded exhaust 118 is then at least partially recovered in a heat transfer heat exchanger 170, which heats the humid air 114 from the humidifier 180, to the steam generator. Heat is applied to the humidifier 180 via the energy saving device 170 '.

  A portion 118A of the expanded and cooled exhaust is exhausted and another portion 118B of the expanded and cooled exhaust is cooled in the cooler 140 to be cooled and expanded (condensing and separating a significant portion of the water). Producing an exhaust stream 118 ′ that is combined with air 132 and compressed in a compressor 130 operably coupled to the expander 120. Accordingly, the compressor 130 supplies the compressed mixed gas 134 cooled in the rear cooler 160, thereby heating at least a portion of the water used in the humidifier. The so-cooled compressed gas mixture 134 is then fed to an acid gas removal unit 150 (preferably a solvent-based acid gas removal unit or a membrane-based carbon dioxide removal unit). The carbon dioxide product stream 152 leaves the plant (eg, as a commercial product) and the compressed mixed gas 136 from which the carbon dioxide has been removed is supplied to the humidifier 180. The humidifier 180 generates a wet gas stream 114 from the compressed mixed gas 136 from which the carbon dioxide has been removed, and the wet gas stream 114 is heated in the heat transfer heat exchanger 170 to produce a heated wet gas stream 114. 'And its gas stream is fed into the combustor 110 (the terms "wet gas stream" and "humid air" are used interchangeably herein).

  Thus, the plant is operably coupled to the expander and expanded with air, combusting fuel in the presence of humid air and expanding in the expander to produce exhaust that produces expanded exhaust. A compressor that compresses at least a portion of the exhaust gas to create a compressed mixed gas, an acid gas removal unit that removes carbon dioxide from the compressed mixed gas to produce a compressed mixed gas, and carbon dioxide is removed. And a humidifier for humidifying the compressed compressed gas mixture.

  Alternatively, in particular, the carbon dioxide is removed in an auto-cooling unit and the exemplary form as represented in FIG. 2 can be used. As described above, the plant 200 includes a humid air turbine cycle that generates power, and at least a portion of the expanded exhaust is recycled back to the compressor for carbon dioxide recovery at elevated pressure. In such a form, combustor 210 receives fuel 212 and heated humid air 214 ′ and produces exhaust 216 that is then expanded in expander 220. The heat in the expanded exhaust 218 is then at least partially recovered in the heat transfer heat exchanger 270, which heats the humid air 214 from the humidifier 280 and a steam generator (not shown). And heats the water to the humidifier 280 via the energy saving device 270 ′. The expanded and cooled exhaust 218 is cooled in cooler 240 to produce a cooled and expanded exhaust stream 218 ′ (while condensing and separating a significant portion of the water), which exhaust stream is coupled with air 232. Compressed in a compressor 230 that is combined and operably coupled to the expander 220. Thus, the compressor 230 provides the compressed mixed gas 234 cooled in the rear cooler 260, thereby heating at least a portion of the water used in the humidifier.

  The compressed mixed gas 234 so cooled is then branched into a first stream 234A supplied to the humidifier 280 and a second stream 234B supplied to the automatic cooling unit 250. The carbon dioxide product stream 252 leaves the plant (eg, as a commercial product), and the carbon dioxide removed exhaust gas 238 leaves the plant as exhaust. The humidifier 280 generates a wet gas stream 214 from the first stream 234A, which is heated in the heat transfer heat exchanger 270 to create a heated wet gas stream 214 ′, and then The gas stream is supplied to the combustor 210.

  Thus, the plant is operably coupled to the expander and expanded with air, combusting fuel in the presence of humid air and expanding in the expander to produce exhaust that produces expanded exhaust. A compressor that compresses at least a portion of the exhaust gas to produce a compressed mixed gas, an automatic cooling unit that removes carbon dioxide from the first portion of the compressed mixed gas, and a second portion of the compressed mixed gas that is humidified And a humidifier that creates humid air.

  In another contemplated configuration, such as that depicted in FIG. 3, an exemplary plant 300 includes a gas turbine (eg, large scale) that has an ability to extract air from 20% to 30% within a moist air turbine cycle that generates power. General Electric 7FA + e) and at least a portion of the expanded exhaust is recycled back to the compressor to recover carbon dioxide at elevated pressure. Here, combustor 310 receives fuel 312 and heated humid air 314 ′ and produces exhaust 316 that is expanded in expander 320. Heat in the expanded exhaust 318 is at least partially recovered in the heat recovery steam generator 370.

  A portion 318A of the expanded and cooled exhaust is exhausted and another portion 318B of the expanded and cooled exhaust is cooled in cooler 340 to be cooled and expanded (condensing and separating a significant portion of the water). Producing an exhaust stream 318 ′ that is combined with air 332 and compressed in a compressor 330 operably coupled to an expander 320. Accordingly, the compressor 330 provides a compressed mixed gas 334. A portion of the compressed gas mixture 334A is fed directly to the combustor 310 (in a manner similar to that performed in a conventional gas turbine) and the other portion 334B of the compressed gas mixture is cooled in the rear cooler 360; Thereby heating at least a portion of the water used in the humidifier. The so-cooled compressed gas mixture 334B is then supplied to an acid gas removal unit 350 (preferably a solvent-based acid gas removal unit or a membrane-based carbon dioxide removal unit). The carbon dioxide product stream 352 leaves the plant (eg, as a commercial product) and the compressed mixed gas 336 from which carbon dioxide has been removed is supplied to the humidifier 380. The humidifier 380 generates a wet gas stream 314 from the compressed mixed gas 336 from which carbon dioxide has been removed, and the wet gas stream 314 is heated in the rear cooler 360 to produce a heated wet gas stream 314 ′. The wet gas stream is supplied to the combustor 310.

  Thus, the contemplated configuration greatly facilitates the recovery of carbon dioxide contained in flue gas having a relatively low carbon dioxide partial pressure, which is particularly desirable in the case of gas turbines where large amounts of excess air are used. Please understand that. Thus, the scale of the carbon dioxide capture device and the power consumed by the blower to overcome the pressure drop of the carbon dioxide capture device (eg, direct contact cooling and absorption devices) is known in many ways. Compared to the proposed form, it can be greatly reduced in the form according to the subject of the present invention.

  Exhaust gas recycling can be used in a number of forms, including a turbine that drives a load (eg, a generator or compressor), but in general, a plant form in which exhaust is at least partially recycled uses a humid air turbine (HAT). An example plant with HAT is described in Rao US Pat. No. 4,829,763, incorporated herein by reference. It should be particularly understood that when the contemplated form comprises a HAT cycle, the previously known difficulties of the HAT cycle can be overcome by the contemplated carbon dioxide removal form. Among other things, the previously known HAT cycle configuration generally required a customized turbomachine, in which the gas turbine compressor had to be much smaller than the expander. Upstream of the expander by removing carbon dioxide from the system in the case of solvent-based processes, or by removing carbon dioxide and other gaseous components in the case of processes based on membranes or autocooling Additional steam can be supplied to the combustor and / or expander without significantly changing the relative flow of gas through the compressor and expander of the engine. Thus, the contemplated configuration not only improves the economics of carbon dioxide recovery in gas turbine based plants, but also regenerates gas turbines (eg, from Sulzer Turbo or MAN GHH Borsig). It is also expected to perform carbon dioxide recovery on a commercially available regenerative gas turbine).

  Furthermore, it is contemplated that the forms and methods according to the present inventive subject matter can be used in relatively low power plants with capacities of 10 MW or less to recover carbon dioxide from combustion gases. Alternatively, contemplated configurations and methods can be included in any plant where a gas turbine is used to drive a compressor or generator.

  It is further contemplated that such separated carbon dioxide can be used in a variety of processes, and particularly contemplated processes include urea plants and enhanced oil recovery. Alternatively, the separated carbon dioxide is sold for medical or nutritional use, used for refrigeration processing, or underground mines, oceans, or other where carbon dioxide can be at least temporarily sequestered Can be sent to the place. Makeup water to the humidifier in the contemplated form can be supplied by a variety of sources including waste water (eg, from within the plant), recycled water, or fresh water.

  With respect to the contemplated acid gas removal unit, it should be understood that all known processes for separating carbon dioxide from gas are suitable in connection with the teachings presented herein. However, particularly preferred methods and forms are those based on physical solvent based processes (eg, US Pat. No. 2,863,527, US Pat. No. 2,926,751, all incorporated herein by reference). No. 3, U.S. Pat. No. 3,505,784, U.S. Pat. No. 2,649,166, or U.S. Pat. No. 3,773,896), chemical solvents. Based processes (see, eg, US Pat. No. 3,563,695, or US Pat. No. 2,177,068, both of which are incorporated herein by reference), membrane processes. (See, eg, US Pat. No. 4,705,540, or US Pat. No. 4,741,744, both of which are incorporated herein by reference.), And Automatic cooling (e.g.,. See U.S. Patent No. 6,301,927, incorporated by reference herein).

  If the carbon dioxide removal involves a membrane or solvent based process as shown in FIG. 1, the amount of expanded exhaust 118B that is recycled can vary significantly and, among other factors, the specific dioxide It should be understood that it depends on the partial pressure of carbon dioxide in the carbon removal unit and / or the compressed gas mixture. Thus, it is generally contemplated that the amount of expanded exhaust 118B that is recycled can be in the range of 0% and 100% by volume of the total expanded exhaust 118. However, particularly when the exhaust gas has a relatively low carbon dioxide partial pressure, the amount of expanded exhaust 118B that is recycled is between about 25% and about 75% by volume of the total expanded exhaust 118. It is preferable.

  Similarly, if automatic cooling is used as shown in FIG. 2, depending on the specific operating parameters, the amount of compressed gas stream 234B supplied to the automatic cooling unit can be varied significantly. I want you to understand. However, under most operating conditions, a suitable amount of compressed gas stream 234B ranges between about 20% and 80% by volume. If the contemplated configuration includes a partial HAT configuration as shown in FIG. 3, the amount of mixed compressed gas 334A delivered directly to the combustor is advantageously between about 5% and 50% by volume. Can do. However, depending on the particular configuration, the amount of mixed compressed gas 334A can be higher than 50% by volume. It is contemplated that the appropriate amount will vary significantly for the cooled and expanded exhaust gas stream 318B that is recycled back to the compressor. In general, however, the amount of cooled and expanded exhaust gas stream 318B is preferably in the range between about 25% and about 75% by volume.

  Mixing of the recycled, cooled, and expanded exhaust gas stream can be done in a number of ways, and all known ways of mixing are properly contemplated herein. For example, if the current plant is later installed in a configuration according to the present inventive subject matter, mixing can take place in a mixing vessel upstream of the compressor inlet. On the other hand, if a form according to the present inventive subject matter is built from the beginning, mixing can be done by feeding recycled gas with fresh air to the compressor inlet.

  Accordingly, the inventor contemplates that the plant can generally comprise a humid air turbine combustor that receives the fuel and the carbon dioxide removed wet gas stream, and at least a portion of the carbon dioxide removed wet gas stream. Is produced from the exhaust gas of a humid air turbine combustor. Such a plant can conveniently further comprise a humidifier, wherein the water used in the humidifier is heated by at least one of a compressed gas mixture and an exhaust gas. The term “gas stream from which carbon dioxide has been removed” as used herein refers to a gas from which at least a portion of the carbon dioxide has been previously removed.

  Viewed from another perspective, a plant in which carbon dioxide has been removed from the exhaust gas of a turbine combustor includes a compressor that compresses air and at least a portion of the exhaust gas that produces a compressed gas mixture, the carbon dioxide being acid gas removed. It is removed from the compressed gas mixture in the unit.

  Thus, specific embodiments and applications of a humid air turbine cycle comprising recovering carbon dioxide have been disclosed. However, it should be apparent to those skilled in the art that many more modifications besides those already described are possible without departing from the inventive concepts herein. . Accordingly, the subject matter of the present invention is not limited except as in the spirit of the appended claims. Moreover, in interpreting both the specification and the claims, all terms should be interpreted in the broadest possible manner consistent with the context. In particular, the terms “comprising” and “comprising” refer non-exclusively to an element, component, or step, whereby the referenced element, component, or step is present, used, or explicitly It should be construed as indicating that it can be combined with other elements, components or steps not referenced.

FIG. 2 is a schematic diagram of an exemplary configuration for recovering carbon dioxide from exhaust gas using a membrane or solvent in an acid gas removal unit. FIG. 6 is a schematic diagram of an exemplary configuration for recovering carbon dioxide from exhaust gas using an automatic cooling unit within an acid gas removal unit. FIG. 6 is a schematic diagram of another exemplary configuration for recovering carbon dioxide from exhaust gas using partial humidification.

Claims (20)

A combustor that combusts fuel in the presence of a wet gas stream, the combustor producing exhaust, the exhaust being expanded in an expander to produce expanded exhaust;
A compressor operably coupled to the expander, wherein the compressor compresses air and at least a portion of the expanded exhaust to produce a compressed gas mixture;
An acid gas removal unit that removes carbon dioxide from the compressed gas mixture to produce a compressed gas mixture from which carbon dioxide has been removed;
A plant comprising a humidifier that humidifies a compressed mixed gas from which carbon dioxide has been removed to create a wet gas stream.   The plant of claim 1, wherein the wet gas stream is heated using exhaust as a heat source, and the heated wet gas stream is supplied to the combustor.   The plant of claim 1, wherein the humidifier uses water heated by at least one of a compressed mixed gas and an exhaust gas.   The plant of claim 1, wherein the acid gas removal unit includes a solvent that absorbs at least a portion of the carbon dioxide.   The plant according to claim 4, wherein the solvent is a chemical solvent.   The plant according to claim 1, wherein the acid gas removal unit comprises a membrane unit.   The plant of claim 1, wherein a portion of the compressed gas mixture is supplied to the combustor.   The plant of claim 1, further comprising a cooler that cools the expanded exhaust and thereby condenses water from the expanded exhaust. A combustor that combusts fuel in the presence of a wet gas stream, the combustor producing exhaust, and the exhaust is expanded in an expander to produce expanded exhaust;
A compressor operably coupled to the expander, wherein the compressor compresses air and at least a portion of the expanded exhaust to produce a compressed gas mixture;
An automatic cooling unit for removing carbon dioxide from the first portion of the compressed gas mixture;
A plant comprising a humidifier that humidifies a second portion of the compressed gas mixture to create a wet gas stream.   The plant of claim 7, wherein the humid gas stream is heated using exhaust as a heat source and the heated humid air is supplied to the combustor.   The plant according to claim 7, wherein the humidifier uses water heated by at least one of a compressed gas mixture and an exhaust gas.   The plant of claim 9, further comprising a cooler that cools the expanded exhaust and thereby condenses water from the expanded exhaust.   A plant comprising a humid air turbine combustor that receives fuel and a carbon dioxide removed wet gas stream, wherein at least a portion of the carbon dioxide removed wet gas stream is produced from the exhaust gas of the humid air turbine combustor plant.   14. A plant according to claim 13, wherein carbon dioxide is extracted from a wet gas stream from which carbon dioxide has been removed using a membrane unit.   14. The plant of claim 13, wherein the carbon dioxide is extracted from the wet gas stream from which the carbon dioxide has been removed using a solvent that absorbs at least a portion of the carbon dioxide.   The plant according to claim 13, further comprising a humidifier, wherein water used in the humidifier is heated by at least one of a compressed mixed gas and an exhaust gas.   Carbon dioxide is removed from the exhaust gas of a turbine combustor with a compressor that compresses air and at least a portion of the exhaust gas to produce a compressed gas mixture, and carbon dioxide is removed from the compressed gas mixture in an acid gas removal unit Plant.   The plant according to claim 17, wherein the acid gas removal unit comprises a membrane unit.   The plant of claim 17, wherein the acid gas removal unit comprises a solvent that absorbs at least a portion of the carbon dioxide.   The plant of claim 17, further comprising a humidifier in which water used in the humidifier is heated by at least one of a compressed mixed gas and an exhaust gas.

Images