Thermal Integration

Abstract

A method is provided for heat integration between a chemical synthesis plant that generates an exothermic reaction and a partner plant that produces a working fluid such as steam (e.g., to run a power cycle). This disclosure describes both internal and external heat integration. In internal heat integration, heat from an exothermic reaction (e.g., from methanol synthesis) may be provided to a reboiler connected to a distillation column of the chemical synthesis plant. In external heat integration, heat from an exothermic reaction may be used to preheat a condensate stream (downstream of the turbine and condenser of the power cycle). This reduces the need for turbine extraction to preheat the condensate as part of the power cycle. The turbine extraction provides heat to a reboiler connected to a distillation column of the chemical synthesis plant. Heat integration results in improved overall energy utilization within both plants.

Description

[Technical Field]

[0001] This disclosure relates to heat integration between processes that are not typically interrelated, as well as systems and methods for implementing or operating such systems. By way of example, such integration may occur in the context of (i) a steam (or other working fluid)-producing plant connected to a power cycle (e.g., generating electricity using a steam turbine or other working fluid turbine) and (ii) a chemical synthesis plant that generates heat from an exothermic reaction. This system can further maximize efficiency, reduce waste heat, lower cooling loads, and the like, by exchanging heat between the plants. It is clear that greenfield sites, in particular, may use steam or other working fluids for purposes other than power generation. For example, in locations with industrial waste heat, it may be more economical to use all of the industrial waste heat as thermal energy, or the steam (or other working fluid) may be used to generate mechanical work (rather than electrical work). Therefore, integration using a power plant as described herein is merely exemplary. Such integration may be referred to as external integration. Internal heat integration, e.g., within a plant, is also described herein. [Background technology]

[0002] Global climate change is considered "the most pressing environmental issue of our time." The National Aeronautics and Space Administration (NASA) has stated that "the scientific evidence for a warming of the climate system is clear." Climate change results from the warming effects of greenhouse gases, such as water vapor, nitrous oxide, methane, and carbon dioxide. In addition to concerns about climate change, there remains a need for greater efficiency in energy generation and overall energy efficiency. For example, power plants in a wide variety of electric power systems rely on the generation of steam (or other working fluids) through various means (e.g., combustion of fossil or other fuels, geothermal, etc.). This steam (or other working fluid) is used in a Rankine cycle or other thermodynamic power cycle to drive a turbine and generate electricity. In a typical power cycle, a portion of the generated steam (or other working fluid) is removed from the turbine (e.g., as low- or intermediate-pressure extraction steam) and used to reheat feedwater after the feedwater flow has passed through the turbine and condenser, preparing it for recirculation through the cycle.

[0003] At the same time, there are many chemical synthesis and other processes that require a supply of cooling water to absorb heat generated during unrelated chemical synthesis or similar processes that involve exothermic reactions. This is because these processes are typically not associated with the power generation process that runs a Rankine cycle or other thermodynamic power cycle and typically operate independently. For example, there is no practical way to integrate heat between such processes, and they are often located far apart. This disclosure relates to practical methods and applications for integrating heat between these processes, thereby reducing the need for low- or medium-pressure bleed air streams removed from turbines in power generation processes to preheat and recycle condensate. This also reduces the amount of cooling water required to absorb heat generated by exothermic reactions associated with chemical synthesis processes.

[0004] Such integration improves the efficiency with which both processes are integrated, leading to better utilization of overall energy resources and enabling a more environmentally friendly process. Summary of the Invention

[0005] The present disclosure relates to systems and methods for improving thermal energy utilization between processes that are not typically associated (e.g., processes that do not otherwise share or exchange feed streams) by integrating heat between those processes. For example, in one specific embodiment, a CRI ETL plant (applicant's emissions-to-liquids (ETL) plant) that converts CO2 emissions and hydrogen (e.g., via water electrolysis) to produce methanol can be integrated with a power plant (e.g., a power plant with a thermodynamic power cycle). Such an ETL plant can be integrated with other processes as well. Waste heat from the ETL plant resulting from the exothermic methanol synthesis reaction is utilized in the power cycle of the power plant. For example, condensate exiting a turbine can be preheated, and then the condensate can be boiled back into steam (or other vaporized working fluid) and sent back to the turbine. The two plants can also be further integrated to redirect a portion of the produced steam (or other working fluid) from the power cycle (e.g., rather than using it in the turbine to generate electricity) and instead utilize it as a heat transfer medium in the ETL process. Thus, instead of passing the steam (or other working fluid) through a turbine to generate electricity, the thermal energy associated with a portion of the steam (or other working fluid) is used for energy distribution purposes in the ETL plant. Such energy distribution can take a variety of forms. For example, in addition to being used for heating purposes (e.g., as part of a distillation process), such steam (or other working fluid) can also be used to drive machinery (e.g., a syngas compressor and / or circulation equipment) within the ETL or other chemical synthesis plant. When used in machinery, thermal energy is converted to mechanical energy. In either case, such integration makes sense and is beneficial when there are synergies in the temperature ranges between the needs of one process relative to the outputs of the other. For example, the temperature suitable for preheating in a thermodynamic cycle power generation process matches the waste heat temperature from the chemical synthesis process.In connection with steam or other working fluid from turbines associated with the reboiler needs of distillation columns (and / or carbon recovery units or other units) of chemical synthesis plants, and vice versa.

[0006] Such integration is beneficial because the efficiency achieved when generating electricity from steam (or other working fluid) (e.g., via expansion through a turbine) is relatively low, e.g., less than 40%. If a portion of the working fluid flow is diverted to the ETL plant and used, for example, to provide heat to a reboiler connected to a distillation column, significantly higher efficiency of energy use within such working fluid is achieved. This is because heat transfer in a heat exchanger can be achieved with much greater energy efficiency than conversion of such working fluid to electrical energy (e.g., and then using the electricity to generate steam or other working fluid to heat the reboiler). While many plants do not use electricity to generate steam (e.g., fuel-powered boilers tend to be more cost-effective), it is desirable to minimize the CO2 footprint of current CRI ETL plants by using green electricity. In either case, the integrated system of the present invention offers an alternative to eliminating the need for steam or other working fluid generators (e.g., by integrating steam (or other working fluid) from a power plant or other partner plant). A reboiler in the distillation section of a chemical synthesis plant is one example where such steam (or other working fluid) may be used, although it will be apparent that such a heated working fluid may be used anywhere. As a further example, the steam or other working fluid may be used for another related purpose in a CO2 capture unit (e.g., a stripper) in an ETL plant, or for another similar purpose in another chemical synthesis plant.

[0007] Both plants benefit from this heat integration. For example, an ETL or other chemical synthesis plant benefits because the steam or other working fluid supplied to it is of greater value to the ETL or other chemical synthesis plant than to the power plant. Waste heat supplied from a chemical synthesis plant to a power plant is beneficial to the power plant because it reduces the amount of working fluid that must be removed from the turbine to reheat the turbine and the condensate leaving the condenser, actually increasing the power produced by the turbine (because more steam or other working fluid is available for power generation). The increase in turbine output can potentially be greater than the exergy content of the supplied waste heat would suggest if the exergy content of the exchanged extracted steam (or other working fluid) is greater than that of the waste heat. Even if a portion of the working fluid is diverted to the ETL plant for heating purposes (e.g., in a distillation system, CO2 capture unit, etc.), the overall efficiency of the process is improved, as shown in the example. ETL plants are beneficial not only in reducing cooling water requirements but also in eliminating the need for steam or other working fluid generators (because the necessary steam or other working fluid is supplied directly from the power plant). Energy use is improved across the integrated system compared to when each process operates independently. Chemical synthesis plants (e.g., Applicant's ETL process), such as plants that convert CO2 emissions into liquid fuels (e.g., methanol) or other useful chemical products, are particularly well suited for integration with power plants or any other plants that can produce steam or other working fluids (e.g., as part of a thermodynamic power cycle). This is because one exemplary chemical synthesis plant (e.g., Applicant's ETL process) can use CO2 exhaust gas from a partner plant as a raw material for use in the synthesis of value-added chemical products (e.g., methanol that can be used as fuel, chemical feedstock for use in other chemical processes, enzyme feed for the production of various compounds such as proteins, or a wide range of other uses).

[0008] By exchanging waste heat from the ETL or other chemical synthesis plant for steam or other working fluid from a partner plant running a power cycle, the waste heat from the ETL or other chemical synthesis plant can be used to preheat the turbine and condensate from the power cycle. Also, a portion of the working fluid transferred from the partner plant running the power cycle can be used to provide heat to the reboiler of a distillation column connected to the ETL or other chemical synthesis plant, to operate mechanical equipment (e.g., compressors, etc.), and / or to provide thermal energy to a CO2 capture unit (e.g., stripper) or other unit. Both plants benefit from this type of heat integration.

[0009] The heat integration embodiments described herein are not limited to those in which one of the plants runs a methanol synthesis process. A wide variety of chemical synthesis or similar processes can be used that provide waste heat in a desired temperature range (e.g., at least 80°C, such as 80°C-200°C, or 100°C-150°C) via an exothermic chemical reaction. Similarly, the partner plant can be any of a wide variety of plants that include a thermodynamic cycle or similar process that produces a high-temperature working fluid stream and requires preheating of condensate (e.g., from a turbine and condenser). A key feature of this embodiment for heat integration is that the temperature provided by the waste heat matches the need for preheating of the condensate.

[0010] This disclosure also describes examples of internal heat integration within a given plant (e.g., an ETL plant). Such an exemplary plant system may include two feed streams, where the first feed stream contains water, which is the source of hydrogen produced in an electrolysis unit, and the second feed stream contains CO2. The system may include an electrolysis unit, a CO2 capture unit, one or more compressors, one or more heat exchangers, a reactor, and a catch pot. The system may further include a catch pot overhead fraction, a distillation column, a condenser, a reflux stream, a distillate stream (e.g., sent to storage), a reboiler, a source of steam or other working fluid, such as from an electric steam generator. Another exemplary system may include a reboiler that reheats a bottom condensate fraction from the distillation column, a pump, first and second heat exchangers. The reboiler supplies a cold stream to the pump, which supplies the cold stream to the first heat exchanger. The first heat exchanger is connected to the outlet of a reactor, where an exothermic reaction occurs. The stream from the outlet of the first heat exchanger is heated to a higher temperature relative to the colder stream and sent to a second heat exchanger where it is further heated to the desired temperature before being sent to a reboiler.

[0011] Such a system may be an emission-to-liquids (ETL) plant.

[0012] The exothermic reaction taking place in the reactor may be a methanol synthesis reaction.

[0013] The second heat exchanger may use steam or other working fluid to produce a high temperature output stream.

[0014] In the following discussion, specific methods, embodiments, and variations of the system are described in more detail.

[0015] These and other features, aspects, and advantages of the present disclosure will become more readily apparent and better understood with reference to the following detailed description, claims, and accompanying drawings. [Brief explanation of the drawings]

[0016] [Figure 1A] Heat Integration According to the Present Disclosure

[0023] FIG. 1 is a schematic diagram of a thermodynamic power cycle shown previously, illustrating how waste heat from an ETL process (or other process with available waste heat) can be integrated into a thermodynamic power cycle, reducing the need to preheat steam or other working fluid, thereby increasing power generation. [Figure 1B] FIG. 1 is a schematic diagram of a thermodynamic power cycle shown after heat integration according to the present disclosure, illustrating how waste heat from an ETL process (or other process with available waste heat) can be integrated into a thermodynamic power cycle, reducing the need to preheat steam or other working fluid, thereby increasing power generation. [Figure 2] FIG. 1 is a schematic diagram of an ETL plant with internal heat integration according to the present disclosure. [Figure 3] FIG. 1 is a schematic diagram illustrating one embodiment of how heat integration can occur between an ETL plant and a partner plant having a thermodynamic power cycle that produces steam or other working fluid. [Figure 4] FIG. 1 is a schematic diagram illustrating another embodiment of how heat (more precisely, both waste heat and higher grade heat from the steam or other working fluid) integration can occur between an ETL plant and a partner plant that includes a thermodynamic power cycle that produces steam or other working fluid. [Figure 5A] FIG. 1B illustrates an example of waste heat integration and shows the increase in power generation that can be achieved compared to the baseline configuration of FIG. 1A, which does not include heat integration. [Figure 5B] 1A illustrates an example of heat integration via steam or other working fluid, eliminating the need for power transport to the ETL plant. While the turbine power output is reduced as a result of diverting a portion of the working fluid, the net power transported is substantially increased compared to the baseline configuration of FIG. 1A, which does not include heat integration. [Figure 5C]FIG. 1B illustrates an example of both heat integration via steam or other working fluid and waste heat integration, further increasing net power delivered compared to the baseline configuration of FIG. 1A, which does not include heat integration.

[0017] The drawings, although not necessarily to scale, are drawn to facilitate a better understanding of the components and are not intended to be limiting in scope but are intended to provide exemplary illustrations.

[0018] Although the drawings illustrate exemplary configurations of heat integration systems and related equipment, they are not intended to limit the structure, configuration, or function of embodiments of heat or working fluid integration systems and related equipment according to the present disclosure. DETAILED DESCRIPTION OF THE INVENTION

[0019] Various embodiments of the present disclosure may be better understood from the following description taken in conjunction with the accompanying drawings, in which like reference numerals refer to similar elements and in which:

[0020] While the present disclosure is susceptible to various modifications and alternative constructions, certain illustrative embodiments are shown in the drawings and described below. It is to be understood, however, that there is no intention to limit the disclosure to the disclosed embodiments, but on the contrary, the invention is intended to cover all modifications, alternative constructions, combinations, and equivalents included within the spirit and scope of the present disclosure and as defined by the appended claims.

[0021] Unless terms are defined herein to have a stated meaning, no intention, explicitly or implicitly, to limit the meaning of such terms beyond their plain or ordinary meaning is to be construed.

[0022] Any heat exchanger described herein may have any suitable heat exchanger configuration, with any suitable characteristics, and operated in any suitable manner. By way of non-limiting example, any given heat exchanger may be a parallel flow heat exchanger, a counter flow heat exchanger, a finned or unfinned tube heat exchanger, a shell-and-tube heat exchanger, a U-tube heat exchanger, a single-pass linear heat exchanger, a two-pass linear heat exchanger, a plate or frame heat exchanger, a finned plate heat exchanger, a microchannel heat exchanger, or other heat exchanger.

[0023] The general term "heat integration" is used to refer to any process in which heat from one process or system is introduced into another process or system. Heat integration, as described herein, can be internal, meaning within a single, independent system or process, or external, meaning that heat from a single, independent system or process is introduced into another, independent process or system. "Independent" means that the system or process can (and typically is) operated independently of, without reference to, or integration with, another system or process (e.g., without the necessary exchange of material flows between such processes). Examples of such independent processes and systems that can undergo heat integration include power generation systems or processes that operate thermodynamic power cycles and chemical synthesis systems or processes that use exothermic reactions. While the present disclosure teaches how heat from each process or system can be integrated into another process or system to improve overall energy efficiency and utilization, all of these processes can (and typically are) operated independently of one another.

[0024] As used herein, references to a Rankine cycle or other thermodynamic power cycle should be construed broadly to refer to a variety of thermodynamic processes for producing useful work (e.g., in the form of generated electrical power). A typical thermodynamic power cycle includes a steam or other working fluid generator (e.g., a boiler), a turbine, a condenser, a pump, and a feedwater preheater, as shown. As described herein, this embodiment of heat integration is not limited to examples of thermodynamic power cycles that actually generate electricity, but should be construed broadly to encompass any of a variety of cycles involving the production of steam or other heated working fluids, which can be used to provide a wide range of functions, such as heating, mechanical work, electricity generation, etc.

[0025] While an emission-to-liquids (ETL) plant that converts carbon dioxide and hydrogen (e.g., via water electrolysis) to methanol is described in principle in embodiments herein as one plant that can be used in the heat integration process of the present invention, it is understood that other plants characterized by exothermic chemical reactions (to obtain usable waste heat) and cooling demands (e.g., cooling water) may also be suitable candidates. For example, other types of chemical synthesis plants that perform thermodynamic reactions as part of the synthesis of a product may be suitable candidates for heat integration, particularly those that utilize a flue gas CO stream as a reactant used in the synthesis of the product.

[0026] Similarly, in the embodiments herein, a power plant is generally described as the other plant (i.e., the partner plant) used in the heat integration process of the present invention. However, it is understood that other plants that similarly operate a thermodynamic power cycle (to obtain usable steam or other working fluid) and require preheated water (or other cycle fluid) from a condenser following a turbine may also be suitable candidates. For example, various plants that include a power cycle turbine for generating electricity may be suitable options for heat integration, regardless of whether power generation is their primary purpose (e.g., a cogeneration plant that may generate electricity for the grid or for internal power needs as a secondary purpose may also be a suitable candidate). For example, one non-limiting example of such a cogeneration plant is a ferrosilicon plant.

[0027] This process of integrating heat sources and demands between two normally separate plants is beneficial because it increases overall energy utilization efficiency, for example, by reducing the cooling water requirements in the ETL or other chemical synthesis plant (which requires significant cooling due to exothermic synthesis reactions) and by increasing the power output of the power plant, since waste heat from the ETL or other chemical synthesis plant is used to preheat the water leaving the power cycle's condenser. Similarly, a portion of the steam or other working fluid produced as part of the power cycle can be diverted to the ETL or other chemical synthesis plant requiring a higher value heat stream (than can be obtained by recovering heat from the ETL's exothermic reactions) to heat the feedstock in a reboiler connected to the ETL plant's distillation column. This stream could be used, for example, in the ETL plant's CO2 capture unit (e.g., stripper) or H2 generation (e.g., electrolysis) unit.

[0028] The benefits to the power cycle are twofold. First, by receiving preheat energy from an ETL or other chemical plant performing exothermic synthesis reactions, more steam or other working fluid can be used to generate electricity instead of being used for heating, thereby increasing the productivity of the plant. Second, the added heat improves the conversion efficiency of the cycle itself, allowing more electricity to be generated for the same amount of energy. While an ETL or other chemical synthesis plant may produce heat of sufficient quality (e.g., high enough temperature) for use within the plant, it may not produce such waste heat streams in sufficient quantities, meaning that additional heat must be captured. However, the remaining waste heat is too low in temperature for use in an ETL or other chemical synthesis plant; however, this low-grade waste heat can be used in the power cycle as described above. As a result, the cycle can be seen to function as an alternative heat pump for an ETL or other chemical synthesis plant, converting low-value heat into high-value heat (e.g., high-temperature steam).

[0029] As shown in the examples, in implementations, the preheating of condenser water and the resulting benefit from the ETL plant to the power plant allows the power plant to generate more electricity (e.g., a 5-6% increase) than if the processes were operated independently. Such examples are based on heat integration from the ETL plant to the power plant (e.g., as shown in FIG. 5A ), without transferring working fluid (e.g., steam) from the power plant to the ETL plant. In other examples (FIGS. 5B-5C), a portion of steam or other working fluid is transferred from the power plant to the ETL plant (e.g., FIG. 5B ), or steam or other working fluid is transferred from the power plant to the ETL plant, with waste heat transferred from the ETL plant to the power plant (FIG. 5C ). In such examples, the flow rate of steam or other working fluid transferred to the ETL plant is greater than the flow rate of steam or other working fluid to the power plant, and the amount of waste heat transferred from the ETL plant is greater to the power plant than to the ETL plant. In both plants, heat integration between them improves overall efficiency, as described herein. For example, changing liquid water to vapor (a phase change) without a temperature change certainly requires a large amount of thermodynamic energy. In the case of the present invention, heat is used efficiently in either of the two physical states of water without expending energy to change the physical state from one state to another (e.g., from liquid to gas).

[0030] FIG. 1A illustrates an operating scheme for an exemplary power plant that generates electricity via a conventional thermodynamic power cycle. As shown, steam or other working fluid can be supplied under pressure (e.g., 41 bar, 440°C) to a turbine to generate electricity (e.g., 32 MW at full load). The spent steam or other working fluid exiting the turbine is sent to a condenser where it is further cooled (e.g., to 25°C) and condensed. The actual temperature of the condensate after cooling can vary widely depending on the location, climate, the type of turbine used, and other factors; the 25°C value is clearly intended as an example only. Such condensate is then pumped to a feedwater heater where it is heated using low-pressure (LP) or intermediate-pressure (MP) extraction steam from the turbine to preheat the condensate (e.g., to 106°C). The preheated water is then sent to a steam or other working fluid generator (i.e., boiler) (not shown) where it is further heated to the desired conditions (e.g., 41 bar, 440°C) at the turbine inlet, and the process begins again. In the operating scheme shown in Figure 1A, the preheated LP extraction steam flow is shown as providing the 4 kg / s required to preheat the given flow rate of water from 25°C to 106°C. Figure 1A also shows an independently operating ETL plant that requires 23.5 MW of power (assuming 98% efficiency) to generate steam. As shown in Figure 1A, when these two systems are operated independently of each other, the net power transport of the two systems is 32 - 23.5 = 8.5 MWe.

[0031] FIG. 1B illustrates a modified operating scheme according to an embodiment of the present disclosure in which heat integration from the ETL (or other plant generating relatively low-grade excess waste heat) is performed. This operating scheme is similar, except that the condensate (e.g., at 25°C) is not fully preheated by the LP preheated working fluid extraction from the turbine, but is first preheated by low-grade waste heat provided by the ETL plant (e.g., heat provided by the synthesis and / or condensation of methanol or other chemicals produced by a partner plant via exothermic reactions). This preheating using heat available from the ETL plant preheats the thermodynamic power cycle condensate to a value intermediate between the cooled and preheated values ​​seen in FIG. 1A (greater than 25°C and less than 106°C). Final preheating of the condensate stream (e.g., to 106°C) is performed by the LP or MP working fluid extraction from the turbine. However, because the majority of the preheating has already been performed by the waste heat provided by the ETL plant, the LP or MP extraction flow rate is significantly less than that required in FIG. 1A. 1A and 1B thus illustrate the general principles applied in this disclosure.

[0032] 4, ideally, the waste heat stream 220 of the ETL plant 100 is sufficient to require the water preheater 210 of the power cycle partner plant. The waste heat stream 220 minimizes or entirely eliminates the need for the extraction steam stream 212, freeing up higher quality steam or other working fluid for more beneficial use (e.g., power generation, use for heating in the ETL plant, or other uses). However, if the waste heat stream 220 alone is not sufficient to heat the water in the preheater 210, the extraction steam stream 212 can be used to meet the need. More information regarding this embodiment is provided below.

[0033] A distillation process that can benefit from the heat integration described herein is described in commonly assigned U.S. Patent No. 10,960,349, published March 30, 2021, the entire disclosure of which is incorporated herein by reference. The distillation process described therein is highly energy-intensive, requiring large amounts of heat in the separation processes, particularly the reboilers of the distillation columns. Steam or other working fluids generated for use in the turbines of a typical power plant's power cycle are particularly suited to supplying the heat required for the reboilers of such distillation processes. Heat is also required in the CO2 capture unit of such ETL processes. Additionally, depending on the technology selected, heat (or steam, in which case both the steam itself and the thermal energy of the steam are available) is also required in the H2 generation unit.

[0034] Of course, within a given process, there is always an incentive to internally integrate available heat to maximize energy efficiency. For example, referring to FIG. 2, one possible scenario for internal heat integration is shown in the context of a typical ETL plant. The ETL plant 100 has two feed streams 102, 104. The first feed stream 102 may contain water, which is fed to an electrolysis unit 106 to produce hydrogen gas. The H may then be compressed in a compressor 108. The second feed stream 104 may consist of a gas containing CO that is fed to a CO capture unit 110. After being compressed in a compressor 112, the CO is mixed with a compressed hydrogen stream in a syngas compressor 114. The resulting syngas may be fed to a heat exchanger 116, where the heated syngas is provided to a methanol reactor 118, and a regenerated or bypass portion is provided to a condenser 122.

[0035] The stream exiting condenser 122 enters catch pot 124, where a top fraction 126 is returned to syngas compressor 114 for regeneration, and a bottom fraction is fed to distillation column 128. The top fraction from distillation column 128 can be fed to condenser 130, a portion of which is returned to distillation column 128 for regeneration as reflux stream 134, and a high purity distilled methanol stream 132 is sent to storage or other desired use. The bottom outlet of distillation column 128 is fed to reboiler 136, which returns the heated distillation column bottoms fraction to distillation column 128.

[0036] The internal heat integration of the ETL plant 100 shown in FIG. 2 serves to reduce the external heat required by the reboiler 136. The reboiler 136 has a cold outlet stream 138, which is fed to a pump 140 to increase its pressure. Stream 142 leaving the pump 140 is fed to a heat exchanger 120 to increase its temperature. The heat exchanger 120 receives heat by being connected to the outlet of the methanol synthesis reactor 118. For example, the heat exchanger 120 may cool the methanol product while transferring waste heat from the exothermic reaction carried out in the reactor 118 to stream 144. Further downstream, the methanol product stream may be further cooled and condensed. Because the synthesis gas-to-methanol reaction is exothermic, the outlet of the reactor 118 fed to the heat exchanger 120 allows for heating of stream 142 resulting from the pump 140. Thus, more efficient use of thermal energy within the system is made to preheat stream 142 while lowering the temperature of the regenerated methanol 154 returned to the methanol reactor 118 to regulate the reaction temperature.

[0037] After exiting heat exchanger 120, the resulting intermediate temperature stream 144 is fed to another heat exchanger 146. Heat exchanger 146 raises the temperature of the heated fluid stream 148 to a temperature high enough for use in heating the distillation bottoms feed in reboiler 136. Heat exchanger 146 may use heat generated from an electric steam generator or other heat transfer medium generator 152 (e.g., direct use of steam or other heat transfer medium). CO2 capture requires energy, provided for example as steam. The plant design shown in FIG. 2 is configured to recover as much heat as practical from the reaction (via heat exchanger 120) and make up the remainder with electrically generated steam or other heat transfer medium. Note that a conventional natural gas or other fuel-powered boiler is not shown for use in generating the necessary steam or other heat transfer medium, as this would generate CO2 emissions and would be undesirable for a plant intended to capture CO2 emissions and convert carbon into value-added products. The loop defined by steam 138, 142, 144, 148 in Figure 2 is a heat transfer medium distribution system that receives heat from a heat source (the exothermic reaction process in reactor 118, the exothermic reaction process in electrically powered generator 152 of steam or other heat transfer medium, and most preferably finally from the power cycle shown in Figure 3) and allows for maximum distribution to user modules as needed. In Figure 2, the heat transfer medium from generator 152 is shown as being fed directly to the CO2 capture unit 110, although an internal loop (although less efficient) could also be used. It will be apparent that heat from the power cycle could also be used in the CO2 capture unit 110 to perform mechanical work or the like (e.g., in a syngas or other compressor).

[0038] In any event, the efficiency of the ETL plant 100 is improved by the use of internal heat integration by using waste heat from the methanol synthesis reactor 118 to preheat the fluid circulating through the reboiler (loop flows indicated at 138, 142, 144, and 148). Even with such internal heat integration, the generator 152 shown in FIG. 2 is still required to fully heat the fluid used to reboil the bottom fraction of the distillation column in the reboiler 136. If the ETL plant is located adjacent to another plant that can provide a high-energy steam or other heat transfer medium flow, the electric heat transfer medium generator can be eliminated. An embodiment of this case is described below.

[0039] For example, as shown in FIG. 3, external heat integration can be implemented, replacing the electric working fluid generator 152 with a heat exchanger 150 connected to a partner plant 200. The partner plant 200 includes a power cycle that produces a working fluid (e.g., steam). A bleed stream of such working fluid can replace the generator 152 by providing the steam or other working fluid as a near-optimal heat transfer medium in exchange for waste heat from the ETL plant. This waste heat is used to preheat the power cycle's condensate or other working fluid. The working fluid diverted from the power cycle is better used to provide the necessary heat to the reboiler 136 (and / or the CO2 capture unit 110 or the H2 generation unit 106) of the ETL plant 100 than to reheat the power cycle's condensate or other working fluid (or to generate further electricity). Similarly, at least a portion of the waste heat from the methanol condenser at the outlet of reactor 118 of ETL plant 100 may be beneficially used to preheat the condensate or other working fluid of the power cycle of plant 200, even though such heat may first be used within the ETL plant, as shown.

[0040] Currently, partner plant 200 generates electricity that can then be purchased by ETL plant 100, which converts the electricity to steam or other heat transfer medium (see, e.g., generator 152 in FIG. 2). Transferring a portion of the steam or other working fluid from the power cycle of partner plant 200 saves energy and makes both processes more efficient, rather than converting it to electricity and then back to steam, which is highly inefficient. For example, converting steam (or other working fluid) to electrical energy (e.g., in turbine 202 of the power cycle) loses approximately two-thirds of the energy in the conversion, and converting the electrical energy back to steam (or other heat transfer medium) in an electric steam generator loses additional energy.

[0041] Referring to FIG. 3 , heat integration (e.g., steam integration) from a power plant to an ETL plant is illustrated. A power generation partner plant 200 includes a turbine 202, a condenser 206, a pump 208, a water preheater 210, and a working fluid generator (e.g., a boiler) 214. These elements comprise the power cycle of the plant 200. Although not shown, a pump is provided downstream of the water preheater 210 to increase the loop pressure (e.g., to approximately 40 bar or higher) prior to heating, boiling, and superheating in the boiler 214. While one preheater 210 is shown in the drawing, it is understood that multiple preheaters may be used in a larger power cycle, for example, where multiple extraction steam and multiple preheaters may be provided. Of course, such configurations are within the scope of the present disclosure. Furthermore, those skilled in the art will understand that feedwater heaters (water preheaters) in a steam power plant can be of either an “open” or “closed” type. In an open-type system, the LP extraction steam and condensate are directly mixed. A closed-type feedwater heater is similar to a conventional heat exchanger in that it transfers heat between two streams without mixing them, allowing for heat transfer between different pressures. Of course, the present disclosure contemplates the use of either type of feedwater heater (open or closed). One or more working fluid extraction streams may also be provided, allowing a portion of the steam or other working fluid to be diverted from the power generation in the turbine 202 for other uses. Such extraction streams may be at any of a variety of desired pressures, such as a low-pressure (LP) extraction stream or a medium-pressure (MP) extraction stream. To integrate the partner plant 200 with the ETL plant 100, a portion of the working fluid (e.g., the MP extraction stream) may be diverted from the turbine 202 and introduced into the heat exchanger 150 as a heat transfer medium. By way of example, the MP extraction stream 204 may be at a temperature between 150 and 200°C and a pressure between 5 and 15 bar. To utilize as much energy as possible, the working fluid is condensed in heat exchanger 150 and returned as condensate. This discharge stream 216 is returned to water preheater 210, where the remaining heat can be used to preheat water coming from condenser 206 and pump 208. This preheated water is then sent to working fluid generator 214, and the power cycle begins again.

[0042] FIG. 4 illustrates heat transfer from the ETL plant to the power cycle in addition to the heat integration (e.g., steam integration) shown in FIG. 3 , showing more complex heat integration between plants 100 and 200. For example, condensed and pressurized water at 20-30°C (or other relatively low condensing temperature) is fed via pump 208 to heat exchanger 123 of ETL plant 100 as cold stream 218. For example, using heat available from an exothermic reaction (e.g., methanol synthesis) performed in reactor 118, the water is heated to approximately 100°C, and this heated stream 220 is sent back to water preheater 210 of power plant 200. As an example, the reactor discharge stream used to heat stream 218 and which is the opposing fluid in heat exchanger 123 may enter heat exchanger 123 at 110°C (e.g., under pressure) and exit at 40°C. This heat integration significantly reduces the flow rate required for the extraction stream 212, resulting in a high-quality stream of significant value (e.g., this stream may be used for further power generation, heat supply to the reboiler 136 of the ETL plant 100, use in the CO2 capture unit 110, or other uses). This also reduces the cooling required to sufficiently cool the stream from the heat exchanger 123 to the catch pot 124. While such a cooling water stream is not shown, the required flow rate of such cooling water is significantly reduced. In this embodiment, the need for most of this high-value extraction stream is replaced by a lower-value stream from the heat exchanger 123 (using heat provided from the exothermic methanol synthesis reaction) provided by the ETL plant 100. The returned heated stream 220 accomplishes most of the required preheating of the discharging stream in the condenser 206, as shown, and any final additional heating can also be accomplished by reducing the flow rate of the extraction stream 212. [Example]

[0043] Figures 5A-5C illustrate three specific examples, based on the configurations shown in Figures 3-4, highlighting the efficiency improvements achieved as a result of such heat integration. These examples can be compared to Figure 1A for a "baseline" comparison. Of course, these examples use steam, but it is clear that other working fluids / heat carriers are possible. Figures 5A-5C demonstrate improved efficiency, including net power generation, without increasing the flow rate of the working fluid to the power cycle system (the flow rate of the 440°C and 41 bar steam remains unchanged). The baseline operation shown in Figure 1A generates 32 MW at full load. However, in the example shown in Figure 5A, with the waste heat provided by the ETL plant 100, only a 0.4 kg / s LP steam extraction transfer is required to circulate water at a target temperature of 106°C. For example, as shown in Figure 5A, the stream returned to the feedwater heater (e.g., preheater 210) can be preheated to 98°C (instead of 25°C in the scenario of Figure 1A) using heat integrated from the ETL plant. The LP extraction steam flow rate is reduced from 4 kg / s to only 0.4 kg / s (a 90% reduction). Consequently, an increased proportion of 440°C, 41 bar steam is fully utilized to generate power in the turbine, resulting in a 5.9% increase in power generation (33.9 MW compared to 32 MW). As shown in FIG. 5A, the ETL plant uses 23.5 MW of power to generate steam, providing a net power transfer of 33.9 - 23.5 = 10.4 MW. The electric steam boiler is assumed to operate at 98% efficiency. The baseline configuration of FIG. 1A provides a net power transfer of 32 - 23.5 = 8.5 MW. Thus, FIG. 5A represents a 22% increase in net power transfer. The embodiment shown in FIG. 5A may be described as providing "heat integration."

[0044] FIG. 5B illustrates an embodiment that may be described as providing “steam integration.” 23 MW of thermal energy in the form of steam is provided from the power plant, eliminating the need for a steam generator at the ETL plant. While this reduces the power generated by the turbine, it increases net power delivery relative to the baseline of FIG. 1A (and also relative to the heat integration shown in FIG. 5A). As shown in FIG. 5B, after the steam is used in the ETL plant, the condensate is returned to the drum, providing a significant amount of heat for use in preheating the condensate in water preheater 210. As a result, the flow rate of the LP extraction stream used to complete the desired preheating is reduced to 1.4 kg / s (compared to 4 kg / s in FIG. 1A). Nevertheless, the turbine can generate 25.2 MW of power, and there is no steam generator power consumption at the ETL plant (since a steam generator is no longer needed). Therefore, net power delivery is 25.2 − 0 = 25.2 MW, representing a 196% increase (nearly three times the original 8.5 MW baseline).

[0045] 5A and 5B, provides both "steam integration" and "heat integration." In this scenario, the LP bleed flow required to achieve final preheating of the condensate in preheater 210 is eliminated (0 kg / sec flow rate), and the turbine can generate 26 MW of power, resulting in a net power delivery of 26-0=26 MW, representing a 205% increase (more than three times the original 8.5 MW baseline).

[0046] Although not illustrated in Figures 5A and 5C, the cooling water requirements in the ETL plant are also significantly reduced (e.g., a 10-20% reduction in the cooling water flow rate required to cool and condense the produced methanol).

[0047] While the examples and much of this disclosure describe heat integration between a power generation plant and a chemical synthesis plant that generates waste heat via an exothermic synthesis reaction, it is understood that the disclosure is not limited thereto. For example, as described herein, a plant may operate a thermodynamic power cycle without actually generating electricity, although the condensed working fluid still needs to be reheated as part of such a cycle (with or without a turbine for generating electricity). By way of example, this may be the case, particularly in greenfield sites, where the power cycle may not generate electricity. There may also be locations with industrial waste heat where it is more economical to use all of the heat as thermal energy. This may be the case in some parts of the world (e.g., Iceland, Norway, etc.), such as ferrosilicon plants or other plants. For example, a waste heat recovery unit may produce steam or other working fluid / heat carrier that can be used for CO2 capture, to run a compressor, for distillation, for district heating of an industrial area, heating of a nearby town, and / or heating of other industries, such as fish farming. While some of these specific cases may not generate electricity, it is clear that the disclosure is not limited thereto.

[0048] In some such cases, heat integration from the ETL plant or other chemical synthesis plant into the power cycle may not be possible because the condensate returned to the power cycle may already be hotter than the waste heat stream from the chemical synthesis plant, such that heat integration may only occur in one direction (e.g., using steam or other working fluid produced in the ETL or other chemical synthesis plant without the need to return waste heat to the plant that runs the power cycle).

[0049] Thus, as will be appreciated by those skilled in the art from the disclosure, features of the disclosed embodiments may be combined or configured to achieve particular advantages. Likewise, features of the disclosed embodiments may provide independent benefits that are applicable to other examples not detailed herein.

[0050] It should be understood that not necessarily all objects or advantages may be achieved in any embodiment of the present disclosure, and those skilled in the art will recognize that systems and methods may be embodied or performed in a manner that achieves or optimizes one or more of the taught advantages without achieving other objects or advantages as taught or suggested.

[0051] Those skilled in the art will recognize the interchangeability of the various disclosed features. In addition to the variations described, other known equivalents for each feature can be mixed and matched by those skilled in the art based on the principles of the present disclosure to achieve or use the integration of heat, steam, and / or other heated working fluids. Those skilled in the art will understand that the described features can be adapted to other systems and processes. Thus, the present disclosure and its embodiments and variations are not limited to a methanol synthesis process or a specific partner plant, but can also be utilized by integrating heat between any exothermic chemical process that produces waste heat and any partner process that produces high-pressure steam or other high-value working fluid / heat carrier.

[0052] While the present disclosure describes specific embodiments and examples of heat integration, it will therefore be understood by those skilled in the art that the present disclosure encompasses other alternative embodiments and / or uses of the present disclosure beyond the specifically disclosed embodiments, as well as obvious modifications and equivalents thereof, and it is not intended that the present disclosure should be limited by the specific disclosed embodiments described above.

[0053] Additionally, unless otherwise specified, numbers expressing quantities, components, distances, or other measurements set forth in the specification and claims should be understood as optionally modified by the term "about" or its synonyms. Terms such as "about," "approximately," and "substantially," when used in connection with a stated amount, value, or condition, can be interpreted to mean an amount, value, or condition that deviates from the stated amount, value, or condition by less than 20%, less than 10%, less than 5%, less than 1%, less than 0.1%, or less than 0.01%. As used herein, the term "between" includes any referenced endpoint. For example, "between 2 and 10" includes both 2 and 10.

Claims

1. 1. A system for heat integration between (i) a partner plant (200) that produces steam or other working fluid as part of a power cycle, and (ii) a chemical synthesis plant that is an ETL (Emission to Liquids) plant (100) that generates heat from an exothermic reaction, comprising: The partner plant (200) a generator (214) of steam or other working fluid; a turbine (202) receiving steam or other working fluid from a steam or other working fluid generator and producing consumed steam or other working fluid; a condenser (206) that receives steam or other working fluid from the turbine and cools and / or condenses the steam or other working fluid from the turbine; a pump (208) that receives cooled and / or condensed vapor or other working fluid from the condenser; a water preheater (210), which may be either open or closed type; a first bleed flow (212) and a second bleed flow (204) from the turbine; The ETL plant (100) comprises: a reactor (118) for providing an exothermic reaction that generates heat; a heat exchanger (150); a distillation column (128) connected to the reactor (118); a reboiler (136) connected to the distillation column (128); the second bleed stream (204) is fed to the heat exchanger (150), and heat from the second bleed stream (204) is used to heat a bottom condensate fraction from the distillation column (128) in a reboiler (136) that does not require heat from the second bleed stream to be converted to electricity; the heat exchanger (150) returns a cold stream (216) to the water preheater (210) connected to the power cycle of the partner plant (200); The heat from the exothermic reaction from the reactor (118) is returned to the water preheater (210) via the heat exchanger (150) to preheat water or other working fluid for the partner plant (200).

2. The system of claim 1, wherein the system is configured to supply power from the power cycle.

3. The system of claim 1, wherein the system is configured to supply thermal energy from the power cycle without generating electricity.

4. The system is configured such that steam or other working fluid from the power cycle operates machinery and equipment, and CO 2 Recovery of and / or H 2 The system of claim 1 , configured for use in performing generation of a

5. The system of claim 1, wherein the turbine is configured to provide the first bleed flow, which is a low-pressure bleed flow.

6. The system of claim 1, configured to supply the second bleed flow which is a medium pressure bleed flow.

7. The system of claim 1 , wherein the condenser comprises a seawater condenser.

8. The system described in claim 1, wherein the pump (208) supplies the condensed low-temperature stream (218) from the turbine to a heat exchanger (123) configured to heat the low-temperature stream by exchanging heat from the exothermic reaction of the ETL plant (100) with the condensed low-temperature stream (218), and returns a preheated stream (220) to a water preheater (210) to provide final heating of the working fluid in a steam or other working fluid generator (214) of the power cycle of the partner plant (200).

9. The system of claim 8, wherein the heat exchanger (123) is configured to return the preheated flow (220), which is a low-quality fluid flow, minimizing or reducing the need to use a high-quality first extraction flow (212) from the turbine (202) in the water preheater.

10. A heat integration system as described in claim 8, wherein the turbine is configured to provide a second extraction flow (204) that is a medium pressure extraction flow.

11. Steam or other working fluid from the power cycle may also or alternatively be used to provide heat to the stripper of a carbon recovery unit (110) and / or to generate H 2 The heat integration system of claim 8 , wherein the heat integration system is used to provide steam or heat to a generating unit (106).

12. The ETL plant (100), a first feed stream (102) and a second feed stream (104); Electrolysis (H 2 a generating unit (106); CO 2 a recovery unit (110); at least one compressor (108, 112, 114); a plurality of heat exchangers (116, 120, 122, 146); Catchpot (124) and a catchpot overhead fraction (126); a condenser (130); a reflux stream (134); and a distillate stream (132) sent to storage; a source of steam or other working fluid; The first feed stream (102) comprises water from which hydrogen is produced in an electrolysis unit, and the second feed stream (104) comprises CO 2 The system of claim 1 , comprising:

13. The system of claim 12 , wherein the source of steam or other working fluid comprises steam from an electric steam generator (152).

14. The system further comprising a system for internal heat integration within the ETL plant (100), The system comprises: further comprising a pump (140); the reboiler (136) supplies a cold stream (138) to the pump (140), which supplies a cold stream (142) to the first heat exchanger (120); the first heat exchanger (120) is connected to the outlet of a reactor (118) in which an exothermic reaction occurs; 13. The system of claim 12, wherein a stream (144) from an outlet of the first heat exchanger (120) is heated to a high temperature relative to the cold stream (142) and then fed to a second heat exchanger (146) to further heat the stream (144) to a desired temperature before feeding it to the reboiler (136).

15. The system of claim 14, wherein the exothermic reaction occurring in the reactor (118) is a methanol synthesis reaction.

16. The system of claim 14, wherein the second heat exchanger (146) is configured to utilize steam or other working fluid to produce a hot output stream (148) for the reboiler.

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