Patent Description:
Power production systems, refining systems, and petrochemical processing systems can involve wasted energy, such as energy generated during process operations. This energy is typically transferred to atmosphere in the form of heat. Power production systems, refining systems, and petrochemical processing systems can also involve CO<NUM> emissions, such as CO<NUM> that can be emitted to atmosphere.

Therefore, there is a need for methods, systems, and apparatus that facilitate collecting CO<NUM>, and recycling operational energy to facilitate reduced carbon footprints, increased cost efficiencies, and increased operational efficiencies (such as thermal efficiencies) for power production systems, refining systems, and/or petrochemical processing systems. <CIT> discloses a Low Emission Power Generation System and Method Incorporating Carbon Dioxide Separation. <CIT> discloses a method and system for producing liquid fuel and generating electric power.

Aspects of the present disclosure relate to steam cycle methods, systems, and apparatus for efficiently reducing carbon footprints of plant systems. In one aspect, a cycle is conducted in a plant system to collect CO<NUM>. In one aspect, a cycle is conducted in a plant system to recycle energy. The plant system includes one or more of a power production system, a refining system, and/or a petrochemical processing system.

The steam cycle system according to the invention is described in claim <NUM>.

In one implementation, a steam cycle system for plant systems includes a fuel feed line to supply a fuel mixture to one or more pieces of equipment of a plant system. The steam cycle system includes a first expansion turbine to couple to an exhaust line of the one or more pieces of equipment, and a first separator. The first separator includes an inlet, a lower outlet coupled to a water feed line, an upper outlet coupled to the fuel feed line. The steam cycle system includes a first heat exchanger unit. The first heat exchanger unit includes a first heat exchanger inlet line coupled to the first expansion turbine, and a first heat exchanger outlet line coupled to the inlet of the first separator. The first heat exchanger unit includes a second heat exchanger inlet line coupled to the water feed line, and a second heat exchanger outlet line coupled to the fuel feed line.

In one implementation, a steam cycle system for plant systems includes a fuel feed line to supply a fuel mixture to one or more pieces of equipment of a plant system. The steam cycle system includes a first expansion turbine to couple to an exhaust line of the one or more pieces of equipment, and a first separator. The first separator includes an inlet, a lower outlet coupled to a water feed line, an upper outlet coupled to the fuel feed line. The upper outlet of the first separator is coupled to the fuel feed line through a compressor coupled to a fuel inlet line. The steam cycle system includes a first heat exchanger unit. The first heat exchanger unit includes a first heat exchanger inlet line coupled to the first expansion turbine, and a first heat exchanger outlet line coupled to the inlet of the first separator. A side outlet line is coupled between the fuel feed line and the first heat exchanger inlet line. The first heat exchanger unit includes a second heat exchanger inlet line coupled to the water feed line, and a second heat exchanger outlet line coupled to the fuel feed line.

The method of operating a power plant according to the invention is described in claim <NUM>.

In one implementation, a method of operating a plant system includes separating nitrogen from a supply of air to generate oxygen, and supplying the oxygen to a fuel mixture in a fuel feed line. The method includes expanding an exhaust flow from one or more heaters of the plant system in a first expansion turbine, and cooling the exhaust flow in a first flow path of a first heat exchanger unit. The method includes separating a liquid composition of the exhaust flow from a gas composition of the exhaust flow. The liquid composition of the exhaust flow includes water and the gas composition of the exhaust flow includes steam and CO<NUM>. The method includes supplying the gas composition of the exhaust flow to the fuel mixture in the fuel feed line, and heating the liquid composition in a second flow path of the first heat exchanger unit to generate a high pressure steam. The method includes expanding the high pressure steam in a second expansion turbine to generate a medium pressure steam, and supplying the medium pressure steam to the fuel mixture in the fuel feed line. The method includes feeding the fuel mixture to the one or more heaters to combust the fuel mixture.

So that the manner in which the above-recited features of the disclosure can be understood in detail, a more particular description of the disclosure, briefly summarized above, may be had by reference to embodiments, some of which are illustrated in the appended drawings. It is to be noted, however, that the appended drawings illustrate only typical embodiments of this disclosure.

It is contemplated that elements disclosed in one implementation may be beneficially utilized on other implementations without specific recitation.

Aspects of the present disclosure relate to steam cycle methods, systems, and apparatus for efficiently reducing carbon footprints in Refining, Petrochemical and Power systems. In one aspect, a cycle is conducted in a plant system to collect CO<NUM>. In one aspect, a cycle is conducted in a plant system to recycle energy. The plant system includes one or more of a power production system, a refining system, and/or a petrochemical processing system.

The present disclosure contemplates that use of terms such as "coupled," "coupled," "couples", and/or "coupling" can include direct coupling and/or indirect coupling, such as coupling through other components. The present disclosure also contemplates that use of terms such as "coupled," "couple," "couples", and/or "coupling" can include connecting, welding, and/or fastening using fasteners, such as pins, rivets, screws, bolts, and/or nuts. The present disclosure also contemplates that use of terms such as "coupled," "couple," "couples", and/or "coupling" can include fluid coupling, such as one or more connections to establish fluid communication.

<FIG> is a schematic partial view of a steam cycle system <NUM>, according to one implementation. The steam cycle system <NUM> is coupled to or a part of a plant system <NUM>. The steam cycle system <NUM> is configured to conduct a steam cycle. The plant system <NUM> includes one or more of a power production system, a refining system, and/or a petrochemical processing system (such as a liquefied natural gas (LNG) system). The steam cycle system <NUM> is coupled to one or more pieces of equipment <NUM> of the plant system <NUM>. The one or more pieces of equipment <NUM> include one or more crackers (such as thermal cracker(s) and/or catalytic cracker(s)), one or more gas turbine generators, and/or one or more heaters (such as combustible heaters, for example furnaces, burners, and/or boilers). The one or more gas turbine generators can be used in the power production system. In one embodiment, which can be combined with other embodiments, the one or more pieces of equipment <NUM> include one or more heaters of the one or more crackers. The one or more heaters can be cogeneration heaters, such as coal-fired cogeneration heaters.

A fuel feed line <NUM> coupled to the one or more pieces of equipment <NUM> feeds a fuel mixture to the one or more pieces of equipment <NUM>. The fuel mixture is combusted in the one or more pieces of equipment <NUM>. The fuel mixture includes oxygen, medium pressure steam, and CO<NUM>. An oxygen line <NUM> is coupled to the fuel feed line <NUM> to supply the oxygen to the fuel feed line <NUM>. An air separation unit <NUM> is coupled to an air line <NUM>, and a first compressor <NUM> is disposed along the air line <NUM>. The air line <NUM> is coupled to an air supply <NUM>. The air supply <NUM> supplies air, such as from atmosphere, to the first compressor <NUM>. The first compressor <NUM> increases a pressure of the air, and the air is supplied to the air separation unit <NUM>. The air separation unit <NUM> separates nitrogen of the air from oxygen of the air, and the oxygen is supplied to the fuel feed line <NUM> using the oxygen line <NUM>. The nitrogen which is separated is supplied to a nitrogen line <NUM>.

A first expansion turbine <NUM> is coupled to an exhaust line <NUM> of the one or more pieces of equipment <NUM>. The exhaust line <NUM> supplies an exhaust flow to the first expansion turbine <NUM>. The exhaust flow includes CO<NUM> and high pressure steam. The exhaust flow can also include ammonia, nitrogen, argon, and/or one or more LNGs. The exhaust flow includes byproducts generated during combustion in the one or more pieces of equipment <NUM>, and exhausted from the one or more pieces of equipment <NUM>. The exhaust flow is flowed through the first expansion turbine <NUM> to reduce the exhaust flow from a high pressure to a medium pressure. The exhaust flow is flowed through the first expansion turbine <NUM> and to a first heat exchanger (HX) inlet line <NUM> coupled to the first expansion turbine <NUM>. The first HX inlet line <NUM> inlets into a first heat exchanger unit (HXU) <NUM>. A side outlet line <NUM> coupled between the fuel feed line <NUM> and the first HX inlet line <NUM> supplies (e.g., returns) medium pressure steam and CO<NUM> to the first HX inlet line <NUM> from the fuel feed line <NUM>, in addition to the exhaust flow supplied using the first expansion turbine <NUM>. The side outlet line <NUM> and the first expansion turbine <NUM> together supply a first HX flow to the first HXU <NUM> through the first HX inlet line <NUM>. The first HX flow in the first HX inlet line <NUM> includes a composition that is <NUM>-<NUM>% by volume or moles (such as <NUM>% by volume or moles) medium pressure steam and <NUM>-<NUM>% by volume or moles (such as <NUM>% by volume or moles) CO<NUM>. The first HX flow includes the exhaust flow received from the one or more pieces of equipment.

The first HX flow flows through the first HXU <NUM> and to a first HX outlet line <NUM>. As the first HX flow flows from the first HX inlet line <NUM>, through the first HXU <NUM>, and to the first HX outlet line <NUM>, the first HX flow exchanges heat with a second HX flow that flows from a second HX inlet line <NUM>, through the first HXU <NUM>, and to a second HX outlet line <NUM>. The first HX inlet line <NUM> and the first HX outlet line <NUM> are a part of a first flow path of the first HXU <NUM>.

As the first HX flow and the second HX flow move (e.g., flow) through the first HXU <NUM>, heat transfers from the first HX flow and to the second HX flow. At least a portion of the medium pressure steam of the first HX flow condenses into water facilitated by the heat transfer in the first HXU <NUM>, and the medium pressure steam is depressurized to a low pressure steam facilitated by the heat transfer in the first HXU <NUM>. The first HX flow in the first HX outlet line <NUM> is supplied to a first separator <NUM> coupled to the first HX outlet line <NUM>. The second HX flow in the second HX inlet line <NUM> includes water in liquid phase. The water is supplied to the second HX inlet line <NUM> using a pump <NUM> coupled to a water feed line <NUM>. The water feed line <NUM> is coupled to the second HX inlet line <NUM> through the pump <NUM>. The water of the second HX flow boils into high pressure steam facilitated by the heat transfer in the first HXU <NUM>, as the second HX flow flows from the second HX inlet line <NUM>, through the first HXU <NUM>, and to the second HX outlet line <NUM>. The first HXU <NUM> is a boiler that boils the second HX flow. The high pressure steam in the second HX outlet line <NUM> is supplied to a second expansion turbine <NUM> coupled to the second HX outlet line <NUM>. The second expansion turbine <NUM> facilitates reducing the pressure of the high pressure steam in the second HX outlet line <NUM> to a medium pressure steam in a side inlet line <NUM> coupled between the second expansion turbine <NUM> and the fuel feed line <NUM>. The side inlet line <NUM> supplies the medium pressure steam to the fuel feed line <NUM>. An operating pressure in the fuel feed line <NUM>, the first HX inlet line <NUM>, the first HX outlet line <NUM>, the second HX inlet line <NUM>, and the side inlet line <NUM> is <NUM> bar or less, such as <NUM> bar or less. An operating pressure in the second HX outlet line <NUM> is within a range of <NUM> bar to <NUM> bar, such as <NUM> bar. The second HX inlet line <NUM> and the second HX outlet line <NUM> are a part of a second flow path of the first HXU <NUM>.

The first separator <NUM> separates a liquid composition (including the liquid water) of the first HX flow from a gas composition of the first HX flow. The gas composition of the first HX flow includes the low pressure steam, the ammonia, and the CO<NUM> of the first HX flow. The liquid composition separated using the first separator <NUM> is supplied to the water feed line <NUM> using a lower outlet <NUM> of the first separator <NUM> that is coupled to the water feed line <NUM>. The gas composition flows to an upper outlet <NUM> of the first separator <NUM>. The gas composition in the upper outlet <NUM> is split and supplied respectively to a second compressor <NUM> and a third expansion turbine <NUM>. A first portion of the gas composition in the upper outlet <NUM> is supplied to the second compressor. A second portion of the gas composition in the upper outlet <NUM> is supplied to the third expansion turbine <NUM> to generate a cycle flow. The upper outlet <NUM> is coupled to the second compressor <NUM> and the third expansion turbine <NUM>. The first portion of the gas composition in the upper outlet <NUM> to the second compressor <NUM> is pressurized in the second compressor <NUM>. The second compressor <NUM> is used to pressurize the low pressure steam of the first portion of the gas composition in the upper outlet <NUM> to a medium pressure steam. The first portion of the gas composition of the exhaust flow (including the medium pressure steam, the ammonia, and the CO<NUM>) is supplied to the fuel feed line <NUM> from the second compressor <NUM> through a fuel inlet line <NUM> coupled between the second compressor <NUM> and the fuel feed line <NUM>.

The second portion of the gas composition of the exhaust flow in the upper outlet <NUM> (including the low pressure steam, the ammonia, and the CO<NUM>) split to the third expansion turbine <NUM> is reduced in temperature and in pressure in the third expansion turbine <NUM> to generate a cycle flow. The cycle flow (including the low pressure steam, the water, the ammonia, and the CO<NUM>) are supplied to a CO<NUM> cycle system <NUM> using a cycle inlet <NUM> coupled to the third expansion turbine <NUM>. A pressure of the cycle flow (including the low pressure steam) is reduced using the third expansion turbine <NUM> such that the pressure is within a range of <NUM> psi-absolute (psia) (<NUM> bar) to <NUM> psia (<NUM> bar) in the cycle inlet <NUM> and the CO<NUM> cycle system <NUM>. The pressure can be less than <NUM> psia (<NUM> bar), such as less than <NUM> psia (<NUM> bar), in the cycle inlet <NUM> and the CO<NUM> cycle system <NUM>. The CO<NUM> cycle system <NUM> is configured to conduct a CO<NUM> cycle. In one embodiment, which can be combined with other embodiments, the CO<NUM> cycle is a low temperature and dry CO<NUM> cycle. In one embodiment, which can be combined with other embodiments, the CO<NUM> cycle system <NUM> is a low temperature heat recovery system or a waste recovery system.

<FIG> is a schematic partial view of the CO<NUM> cycle system <NUM> shown in <FIG>, according to one implementation. The CO<NUM> cycle system <NUM> includes a second separator <NUM>. A second cycle flow (including one or more of low pressure steam, water, ammonia, and/or CO<NUM> either alone or in any combination thereof) are supplied to an inlet <NUM> of the second separator <NUM> from a first HX outlet line <NUM>. A lower outlet <NUM> of the second separator <NUM> separates a liquid phase of the second cycle flow from a gas phase of the second cycle flow. The liquid phase of the second cycle flow exits the second separator <NUM> at the lower outlet <NUM>. The gas phase of the second cycle flow exits the second separator <NUM> at an upper outlet <NUM>. The liquid phase (including water) of the second cycle flow proceeds to a pump line <NUM> coupled to a second pump <NUM>. The lower outlet <NUM> is coupled to the pump line <NUM>. The second pump <NUM> is a multi-phase pump. The gas phase of the second cycle flow proceeds to a fourth expansion turbine <NUM> coupled to the upper outlet <NUM>. The fourth expansion turbine <NUM> is coupled to the pump line <NUM>.

The liquid phase of the second cycle flow and the gas phase flowing through the pump line <NUM> are pumped using the second pump <NUM> to a first HX inlet line <NUM> of the second HXU <NUM>. The first HX inlet line <NUM> is coupled to the pump line <NUM> through the second pump <NUM>. The liquid phase and the second portion of the gas phase split to the pump line <NUM> flow from the first HX inlet line <NUM>, through the second HXU <NUM>, and to a first HX outlet line <NUM> of the second HXU <NUM>.

The second HXU <NUM> includes a second HX inlet line <NUM> and a second HX outlet line <NUM> coupled to any low temperature heat source of plant system <NUM>. One or more low temperature heat streams from the second HX inlet line <NUM> flow through the second HXU <NUM>, and to the second HX outlet line <NUM>. The cycle flow exits the third expansion turbine <NUM> (shown in <FIG>) and flows from the cycle inlet <NUM> and into a third HX inlet line <NUM> of the second HXU <NUM> as a third stream. The cycle flow acting as the third stream is utilized as a hot stream and is cooled as the cycle flow flows through the second HXU <NUM> that is coupled to a cycle outlet <NUM> through a third HX outlet line <NUM>. The cycle outlet <NUM> is routed back to a third separator <NUM> shown in <FIG>. Heat transfers from the cycle inlet <NUM> and to the first HX inlet line <NUM>. Heat also transfers from the second HX inlet line <NUM> and to the first HX inlet line <NUM>. The liquid phase and the gas phase of the second cycle flow flows to the pump line <NUM>. A temperature of the liquid phase and the gas phase of the second cycle flow in the pump line <NUM> is increased in the second HXU <NUM>. The liquid phase and the gas phase of the second cycle flow then flows to the inlet <NUM> of the second separator <NUM> through the first HX outlet line <NUM>. An operating pressure in the inlet <NUM>, the pump line <NUM>, and/or the first HX inlet line <NUM> is within a range of <NUM> bar to <NUM> bar, such as <NUM> bar.

The inlet of the third separator <NUM> is coupled to the cycle outlet <NUM> from the second HXU <NUM>. The third separator <NUM> separates a liquid composition (such as water and/or ammonia) of the outlet flow from a gas composition of the outlet flow. The liquid composition separated in the third separator <NUM> exits at a lower outlet <NUM> of the third separator <NUM>. The lower outlet <NUM> is coupled to the water feed line <NUM>. The liquid composition flows from the lower outlet <NUM> and to the water feed line <NUM>. The gas composition of the outlet flow exits the third separator <NUM> at an upper outlet <NUM> of the third separator <NUM>. The gas composition exiting the third separator <NUM> at the upper outlet <NUM> is mostly CO<NUM>. The gas composition exiting the third separator <NUM> at the upper outlet <NUM> is <NUM>-<NUM>% CO<NUM> by mass, volume, or moles (such as <NUM>-<NUM>% CO<NUM> by mass). The gas compositions having CO<NUM> in the upper outlet <NUM> is not vented to atmosphere but is collected in a CO<NUM> collector <NUM> (such as in a tank) for re-use or is fed to other equipment of the plant system <NUM> for re-use. The upper outlet <NUM> is coupled to the CO<NUM> collector <NUM>. Collecting the CO<NUM> for re-use facilitates reducing CO<NUM> emissions for the plant system <NUM> and reducing the carbon footprint of the plant system <NUM>. A first temperature of the CO<NUM> in the cycle inlet <NUM> is within a range of <NUM> degrees Fahrenheit to <NUM> degrees Fahrenheit. A second temperature of the CO<NUM> in the cycle outlet <NUM> is within a range of <NUM> degrees Fahrenheit to <NUM> degrees Fahrenheit. Aspects of the disclosure facilitate collecting and reusing energy generated in the plant system <NUM>, rather than releasing the CO<NUM> to atmosphere at the first temperature.

The present disclosure contemplates that each of the separators <NUM>, <NUM>, <NUM> can be a gravity separator, such as a vertical separator or a horizontal separator. The present disclosure contemplates that each of the separators <NUM>, <NUM>, <NUM> can alternatively be a phase separator. It is noted that the separators the <NUM>, <NUM>, and <NUM> need not all be the same type of separator (e.g., gravity of phase). Each of the turbines <NUM>, <NUM>, <NUM>, <NUM> is rotatable to generate electricity. The electricity generated using the turbines <NUM>, <NUM>, <NUM>, <NUM> can be used in other equipment of the plant system <NUM>, such as the compressors <NUM>, <NUM> and/or the pumps <NUM>, <NUM>. The steam cycle system <NUM> has a thermal efficiency of <NUM>% or greater, and facilitates reduced CO<NUM> emissions for Refining, Petrochemical and Power systems.

The present disclosure contemplates that the steam cycle system <NUM> and the CO<NUM> cycle system <NUM> can be implemented and retrofitted into existing Refining, Petrochemical and Power systems.

<FIG> is a schematic view of a method <NUM> of operating a plant system, according to one implementation. The plant system includes one or more of a power production system, a refining system, and/or a petrochemical processing system (such as a liquefied natural gas (LNG) system). Operation <NUM> of the method <NUM> includes separating nitrogen from a supply of air to generate oxygen. In one embodiment, which can be combined with other embodiments, the supply of air is compressed in a first compressor prior to separating the nitrogen from the supply of air at operation <NUM>. Operation <NUM> includes supplying the oxygen to a fuel mixture in a fuel feed line.

Operation <NUM> includes expanding an exhaust flow from one or more heaters of the plant system in a first expansion turbine. Operation <NUM> includes cooling the exhaust flow in a first flow path of a first heat exchanger unit. Operation <NUM> includes separating a liquid composition of the exhaust flow from a gas composition of the exhaust flow. The liquid composition of the exhaust flow includes water and the gas composition of the exhaust flow includes steam and CO2.

Operation <NUM> includes supplying the gas composition of the exhaust flow to the fuel mixture in the fuel feed line. In one embodiment, which can be combined with other embodiments, the supplying the gas composition of the exhaust flow to the fuel mixture in the fuel feed line includes compressing the gas composition of the exhaust flow in a second compressor. In one embodiment, which can be combined with other embodiments, a portion of the gas composition of the exhaust flow supplied to the fuel mixture in the fuel feed line is returned to the first flow path of the first heat exchanger unit.

Operation <NUM> includes supplying the gas composition of the exhaust flow to a third expansion turbine to generate a cycle flow, and operation <NUM> includes conducting a CO<NUM> cycle on the cycle flow. The CO<NUM> cycle includes one or more of the operations, aspects, components, properties, and/or features of the CO<NUM> cycle conducted using the CO<NUM> cycle system <NUM> described above. Operation <NUM> includes collecting a gas composition of the outlet flow. The gas composition of the outlet flow includes CO<NUM>.

Operation <NUM> includes heating the liquid composition in a second flow path of the first heat exchanger unit to generate a high pressure steam. Operation <NUM> includes expanding the high pressure steam in a second expansion turbine to generate a medium pressure steam.

Operation <NUM> includes supplying the medium pressure steam to the fuel mixture in the fuel feed line. Operation <NUM> includes feeding the fuel mixture to the one or more heaters to combust the fuel mixture.

The present disclosure contemplates that one or more (such as all) of the operations <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, and/or <NUM> can be conducted simultaneously.

Benefits of the present disclosure include collecting CO<NUM>, recycling operational energy, reduced carbon footprints, increased cost efficiencies, and increased operational efficiencies (such as thermal efficiencies) for plant systems. As an example, it is believed that the aspects described herein can reduce the carbon footprint of a plant system (which can include one or more of a power production system, a refining system, and/or a petrochemical processing system) by a factor of <NUM> or more at a thermal efficiency of <NUM>% or greater. As another example, it is believed that the aspects described herein can eliminate CO<NUM> emissions of heaters (such as combustion heaters) or crackers at a thermal efficiency of <NUM>% or greater.

It is contemplated that one or more of these aspects disclosed herein may be combined. Moreover, it is contemplated that one or more of these aspects may include some or all of the aforementioned benefits. As an example, the present disclosure contemplates that one or more of the aspects, features, components, operations, and/or properties of the steam cycle system <NUM>, the plant system <NUM>, the CO<NUM> cycle system <NUM>, and/or the method <NUM> may be combined.

Claim 1:
A steam cycle system for plant systems, comprising:
a fuel feed line (<NUM>) to supply a fuel mixture to one or more pieces of equipment of a plant system;
a first expansion turbine (<NUM>) to couple to an exhaust line (<NUM>) of the one or more pieces of equipment;
a first separator (<NUM>) comprising:
an inlet,
a lower outlet (<NUM>) coupled to a water feed line, and
an upper outlet (<NUM>) coupled to the fuel feed line; and
a first heat exchanger unit (<NUM>) comprising:
a first heat exchanger inlet line (<NUM>) coupled to an outlet of the first expansion turbine,
a first heat exchanger outlet line (<NUM>) coupled to the inlet of the first separator,
a second heat exchanger inlet line (<NUM>) coupled to the water feed line, and
a second heat exchanger outlet line (<NUM>) coupled to the fuel feed line.