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] The present disclosure relates to heat integration between processes that are not typically associated with each other, as well as systems and methods for implementing or operating such systems. As an example, such integration may occur in relation to (i) a plant that produces steam (or other working fluid) 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 produces heat from an exothermic reaction. The system may further maximize efficiency, reduce waste heat, reduce cooling loads, etc. by exchanging heat between the plants. It is clear that in particular greenfield sites may use steam or other working fluids for other purposes than generating electricity. 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). Thus, the integration with a power plant as described herein is merely exemplary. Such integration may be referred to as external integration. Internal heat integration, e.g., within the plant, is also described herein. [Background technology]

[0002] Global climate change is considered to be 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 is still a need to increase the efficiency of energy generation and to use energy more efficiently overall. For example, power plants in a wide variety of electric power systems rely on the generation of steam (or other working fluids) by 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 run a turbine to 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 medium pressure extraction steam) and used to reheat the feedwater flow after it has passed through the turbine and a condenser, in preparation for the feedwater to circulate through the cycle again.

[0003] At the same time, there are many chemical synthesis and other processes that require the supply of cooling water to absorb heat generated during chemical synthesis or similar processes that involve exothermic reactions but are not related to each other because they are not typically associated with the power generation process that runs the 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 far apart. The present disclosure relates to practical methods and applications of integrating heat between such processes, which can reduce the need for low or medium pressure bleed air streams taken from the turbine in the power generation process to preheat and recycle the condensate. Also, the cooling water required to absorb heat generated by exothermic reactions associated with chemical synthesis processes can be reduced.

[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 the utilization of thermal energy between processes that are not typically associated (e.g., processes that do not otherwise share or exchange feed streams) by integrating heat between the 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., from 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 methanol synthesis, an exothermic reaction, is utilized in the power cycle of the power plant. For example, the condensate coming out of the 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 again. The two plants can also be further integrated to redirect a portion of the generated steam (or other working fluid) from the power cycle (e.g., rather than being used by the turbine to generate electricity) and instead be utilized in the ETL process as a heat carrier. 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., syngas compressors and / or circulation equipment) in an ETL or other chemical synthesis plant. When used in machinery, thermal energy is converted to mechanical energy. In any case, such integration makes sense and is beneficial when there are synergies in the temperature ranges between the needs of one process relative to what is available from the other process. For example, the appropriate temperature 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 a turbine associated with the reboiler needs of a distillation column (and / or carbon recovery unit or other unit) of a chemical synthesis plant, 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, e.g., to provide heat to a reboiler connected to a distillation column, a significantly higher efficiency of energy use in such working fluid is achieved. This is because heat transfer in a heat exchanger can be achieved with much higher energy efficiency than conversion of such working fluid to electrical energy (e.g., and then using electrical power to generate steam or other working fluid to heat the reboiler). While many plants do not use electrical power to generate steam (e.g., fuel-powered boilers tend to be more cost-effective), it is desirable to minimize the CO2 footprint in 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, but 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 in another related application in a CO2 capture unit (e.g., a stripper) of an ETL plant, or in another similar application in another chemical synthesis plant.

[0007] Both plants benefit from this heat integration. For example, the ETL or other chemical synthesis plant benefits because the steam or other working fluid fed to it is of greater value to the ETL or other chemical synthesis plant than to the power plant. Waste heat fed from the chemical synthesis plant to the 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, and actually increases the power produced by the turbine (because more steam or other working fluid is available for generating electricity). The increase in turbine power output can potentially be greater than would be suggested by the exergy content of the waste heat fed in, if the exergy content of the exchanged extraction 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 increased, as shown in the examples. ETL plants are beneficial in that they not only reduce the cooling water required, but also eliminate the need for steam or other working fluid generators (since the required steam or other working fluid is provided directly from the power plant). Energy usage is improved throughout the integrated system compared to when each process operates independently. Chemical synthesis plants (such as, for example, the 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 may generate steam or other working fluids (e.g., as part of a thermodynamic power cycle), because the chemical synthesis plants considered as one example (e.g., the applicant's ETL process) can use CO2 exhaust gas from partner plants 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 with steam or other working fluid from the partner plant running the power cycle, the waste heat from the ETL or other chemical synthesis plant can be used to preheat the condensate from the turbine and condenser of 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 the distillation column connected to the ETL or other chemical synthesis plant, to run mechanical equipment (e.g., compressors, etc.), and / or to provide heat energy to a CO2 capture unit (e.g., stripper) or other units. Both plants benefit from such 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 processes or similar processes can be used that provide waste heat in the desired temperature range (e.g., at least 80°C, such as 80°C-200°C, or 100°C-150°C) via exothermic chemical reactions. 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 the condensate (e.g., from the turbine and condenser). An important feature of this embodiment for heat integration is that the temperature provided by the waste heat matches the need for preheating 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 a first feed stream includes water from which hydrogen is produced in an electrolysis unit, and a second feed stream includes CO2. An electrolysis unit, a CO2 capture unit, one or more compressors, one or more heat exchangers, a reactor, and a catch pot may be provided. The system may further include a catch pot top 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, e.g., from an electric steam generator. Another exemplary system may include a reboiler for reheating a bottom condensate fraction from the distillation column, a pump, and first and second heat exchangers. The reboiler provides a cold stream to the pump, which in turn provides the cold stream to the first heat exchanger. The first heat exchanger is connected to the outlet of the reactor, in which an exothermic reaction takes place. The stream from the outlet of the first heat exchanger is heated to a higher temperature relative to the cooler stream and sent to a second heat exchanger where it is further heated to the desired temperature and then sent to a reboiler.

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

[0012] The exothermic reaction carried out in the reactor may be a methanol synthesis reaction.

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

[0014] In the discussion that follows, 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 description of the drawings]

[0016] [Figure 1A] FIG. 1 is a schematic diagram of a thermodynamic power cycle shown previously with 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 to reduce 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 to reduce the need to preheat steam or other working fluid, thereby increasing power generation. [Diagram 2] FIG. 1 is a schematic diagram of an ETL plant with internal heat integration according to the present disclosure. [Diagram 3] FIG. 1 is a schematic diagram illustrating one embodiment of how heat integration may be performed 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 be performed 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 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 embodiment of heat integration via steam or other working fluid, and shows the elimination of the need for power transport to the ETL plant. Although the diversion of a portion of the working fluid results in a reduction in turbine power production, the net power transported is substantially increased compared to the baseline configuration of FIG. 1A, which does not include heat integration. [Figure 5C]FIG. 1C illustrates an example of both heat integration via steam or other working fluid and waste heat integration, which further increases the 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 example 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 integrated systems and related equipment according to the present disclosure. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[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 numbers indicate 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 in this application to have a stated meaning, no intention is to be construed as explicitly or implicitly limiting the meaning of such terms beyond their plain or ordinary meaning.

[0022] Any heat exchanger described herein may have any suitable heat exchanger configuration, having any suitable characteristics, and operated in any suitable manner. As non-limiting examples, any given heat exchanger may be a parallel flow heat exchanger, a counterflow heat exchanger, a finned or unfinned tube heat exchanger, a shell-and-tube heat exchanger, a U-tube heat exchanger, a single pass straight heat exchanger, a two pass straight 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 mean any process in which heat from one process or system is introduced into another process or system. The heat integration described in this embodiment 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. By "independent" we mean that the system or process can (and typically is) carried out independently of, without regard 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 run thermodynamic power cycles, and chemical synthesis systems or processes that use exothermic reactions. Although 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 energy utilization, all of these processes can (and typically are) carried out independently of each other.

[0024] As used herein, references to a Rankine cycle or other thermodynamic power cycle should be interpreted broadly and 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 generator of steam or other working fluid (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 electrical power, but should be interpreted broadly to encompass any of a variety of cycles that involve the generation of steam or other heated working fluid, which can be used to provide a wide range of functions, such as, for example, heating, mechanical work, electrical generation, etc.

[0025] Although an ETL plant that converts carbon dioxide and hydrogen (e.g., from water electrolysis) to methanol is described in principle in embodiments herein as one of the plants that can be used in the heat integration process of the present invention, it is understood that other plants that are 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, especially those that utilize a flue gas CO2 stream as a reactant used in the synthesis of the product.

[0026] Similarly, in the embodiments herein, a power plant is described as the other plant (i.e., the partner plant) used in the heat integration process of the present invention, in principle. However, it is understood that other plants that also run a thermodynamic power cycle (to obtain usable steam or other working fluid) and require preheating 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 generating electricity 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, a ferrosilicon plant is one non-limiting example of such a cogeneration plant.

[0027] This process of integrating heat sources and heat demands between two normally independent plants is beneficial because it increases the 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 also 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 condenser of the power cycle. Similarly, a portion of the steam or other working fluid generated as part of the power cycle can be diverted to the ETL or other chemical synthesis plant that requires a higher value heat stream (than can be obtained by recovering heat from the exothermic reactions of the ETL) to heat the feed in a reboiler connected to the distillation column of the ETL plant. This stream can be used, for example, in the CO2 capture unit (e.g., stripper) or in the H2 production (e.g., electrolysis) unit of the ETL plant.

[0028] The advantage to the power cycle is twofold. First, by receiving preheat energy from the 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, thus increasing the productivity of the plant. Second, the added heat increases the conversion efficiency of the cycle itself, allowing more electricity to be generated for the same energy. Although 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, which means that additional heat needs to be captured. However, the remaining waste heat is too low in temperature for use by the ETL or other chemical synthesis plant, but such low grade waste heat can be used in the power cycle as described above. As a result, it can be seen that the cycle acts as an alternative heat pump for the ETL or other chemical synthesis plant, converting low value heat to high value heat (e.g., high temperature steam).

[0029] As shown in the examples, in implementations, the condenser water is preheated and the ETL plant benefits the power plant, allowing the power plant to generate more power (e.g., 5-6% more) than if the processes were run independently. Such examples are based on heat integration from the ETL plant to the power plant (e.g., as shown in FIG. 5A), where no working fluid (e.g., steam) is transferred from the power plant to the ETL plant. In other examples (FIGS. 5B-5C), a portion of the 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 and waste heat is transferred from the ETL plant to the power plant (FIG. 5C). In such examples, the flow rate of the steam or other working fluid transferred to the ETL plant is greater than the flow rate of the 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, the heat integration between them improves the overall efficiency as described herein. For example, changing liquid water to steam (phase change) without a change in temperature 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 by a conventional thermodynamic power cycle. As shown, steam or other working fluid can be fed under pressure (e.g., 41 bar, 440° C.) to a turbine to generate electricity (e.g., 32 MW at full load). Spent steam or other working fluid leaving 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 and climate, the type of turbine used, and other factors, and it is clear that the value of 25° C. is merely exemplary. Such condensate is then pumped to a feedwater heater where it is heated using low pressure (LP) or medium pressure (MP) extraction steam flow 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) to be 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 preheat LP extraction stream is shown to provide a flow rate of 4 kg / sec required to preheat the given flow rate of water from 25°C to 106°C. Also shown in Figure 1A is an independently operating ETL plant that requires 23.5 MW of power (assuming 98% efficiency) to generate steam. If these two systems are operated independently of each other as shown in Figure 1A, the net power transport of the two systems is 32-23.5=8.5 MWe.

[0031] FIG. 1B shows a modified operating scheme according to an embodiment of the present disclosure, where heat integration from the ETL (or other plant generating relatively low-grade excess waste heat) is performed. This operating scheme is the same, 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 the partner plant, resulting from exothermic reactions). Such preheating with heat available from the ETL plant preheats the condensate of the thermodynamic power cycle to a value that is intermediate between the cooled and preheated values ​​seen in FIG. 1A (>25° C. and <106° C.). The 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, the LP or MP extraction flow rate is now significantly less than required in FIG. 1A, since most of the preheating has already been performed by the waste heat provided by the ETL plant. Thus, Figures 1A and 1B 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 a water preheater 210 at the power cycle partner plant. The waste heat stream 220 minimizes or completely eliminates the need for the extraction stream 212, freeing up higher quality steam or other working fluid for more beneficial use (e.g., generating electricity, using 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 stream 212 can be used to fill the need. More information regarding this embodiment is provided below.

[0033] A distillation process that may benefit from the heat integration described herein is described in commonly-owned 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 a highly energy-intensive process that requires a large amount of heat in the separation process, particularly in the reboiler of the distillation column. Steam or other working fluids generated for use in the turbines of a typical power plant power cycle are particularly suitable for use in providing the heat required for the reboiler of such distillation processes. Heat is also required in the CO2 capture unit of such an ETL process. In addition, 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, depending on the technology selected.

[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 within 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 that is fed to an electrolysis unit 106 to produce hydrogen gas. The H2 may then be compressed in a compressor 108. The second feed stream 104 may consist of gas containing CO2 that is fed to a CO2 capture unit 110. After the CO2 is compressed in a compressor 112, it is mixed with a compressed hydrogen stream in a syngas compressor 114. The resulting syngas may be fed to a heat exchanger 116, whereby 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 leaving 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 in 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. Since the synthesis gas to methanol reaction is an exothermic reaction, it allows the outlet of the reactor 118 fed to the heat exchanger 120 to heat the stream 142 coming from the pump 140. Thus, the thermal energy in the system is more efficiently utilized 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 leaving the heat exchanger 120, the resulting mid-range stream 144 is fed to another heat exchanger 146. The 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 the reboiler 136. The 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 the 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 required steam or other heat transfer medium, as this would generate CO2 emissions and would be undesirable for a plant intended to capture the CO2 emissions and convert the 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 (exothermic reaction process in reactor 118, 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 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, but an internal loop (albeit 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 case, 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 reboiler circulating fluids (loop flows indicated at 138, 142, 144, 148). Even with such internal heat integration, the generator 152 shown in FIG. 2 is still required to fully heat the fluids 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 medium flow, the electric heat medium generator can be eliminated. An embodiment of this case will be described below.

[0039] For example, as shown in FIG. 3, external heat integration can be introduced and the electric working fluid generator 152 can be replaced by 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 carrier in exchange for waste heat from the ETL plant. This waste heat is used to preheat the condensate or other working fluid of the power cycle. The working fluid transferred from the power cycle is better used in providing the required 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 condensate or other working fluid of the power cycle (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 in preheating the condensate or other working fluid of the power cycle of plant 200, even if such heat could 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 into steam or other heat transfer medium (see, e.g., generator 152 in FIG. 2). Energy is saved and both processes are more efficient if a portion of the steam or other working fluid is transferred out of the power cycle of partner plant 200, rather than converted into electricity and then back into 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 about two-thirds of the energy in the conversion, and converting the electrical energy back into steam (or other heat transfer medium) in an electric steam generator loses even more energy.

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

[0042] FIG. 4 illustrates the heat transfer from the ETL plant to the power cycle in addition to the heat integration (e.g., steam integration) shown in FIG. 3, and shows a 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 about 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, making it a higher quality stream with significant value (e.g., this stream can be used to generate additional power, provide heat to the reboiler 136 of the ETL plant 100, for use in the CO2 capture unit 110, or other uses). In addition, this also reduces the cooling required to sufficiently cool the stream from the heat exchanger 123 to the catch pot 124. Although 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 reaction of the methanol synthesis) provided by the ETL plant 100. The returned heated stream 220 achieves most of the required preheating of the condenser 206 discharging stream as shown, and any final further heating can also be achieved by reducing the flow rate of the extraction stream 212. EXAMPLES

[0043] 5A-5C illustrate three specific examples based on the configurations shown in, for example, FIGS. 3-4, focusing on the efficiency improvements achieved as a result of such heat integration. These examples can be compared to FIG. 1A for a "baseline" comparison. Of course, steam is used in these examples, but it is clear that other working fluids / heat carriers are possible. In FIGS. 5A-5C, the efficiency, including the net power generation, is improved without increasing the flow rate of the working fluid to the power cycle system (the flow rate of the steam at 440° C. and 41 bar is unchanged). The baseline operation shown in FIG. 1A generates 32 MW at full load. However, in the example shown in FIG. 5A, only 0.4 kg / s of LP steam extraction is required to circulate the target 106° C. water with the waste heat provided by the ETL plant 100. For example, as shown in FIG. 5A, the flow returned to the feedwater heater (e.g., preheater 210) can be preheated to 98° C. (instead of 25° C. in the scenario of FIG. 1A) with the heat integrated from the ETL plant. The LP extraction flow rate is reduced from 4 kg / s to only 0.4 kg / s (a 90% reduction). As a result, the percentage of 440° C., 41 bar steam fully utilized for generating electricity in the turbine increases, resulting in a 5.9% increase in power generation (33.9 MW versus 32 MW). As shown in FIG. 5A, the ETL plant uses 23.5 MW of power to generate steam, providing a net power delivery 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 delivery of 32-23.5=8.5 MW. Thus, FIG. 5A represents a 22% increase in net power delivery. 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 by the power plant, eliminating the need for a steam generator in the ETL plant. This reduces the power generated by the turbine, but increases the net power delivery compared to the baseline in FIG. 1A (and also compared 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 to provide a large amount of heat for use in preheating the condensate in the water preheater 210. As a result, the flow rate of the LP extraction stream used to complete the desired preheat is reduced to 1.4 kg / s (compared to 4 kg / s in FIG. 1A). Still, the turbine is able to generate 25.2 MW of power, and there is no power consumption by the steam generator in the ETL plant (since the steam generator is no longer required). Thus, the net power delivery is 25.2-0=25.2 MW, which represents a 196% increase (nearly three times the original 8.5 MW baseline).

[0045] 5C shows an embodiment that combines the integration seen in Figures 5A and 5B to provide both "steam integration" and "heat integration." In this scenario, the LP extraction flow required to achieve final pre-heating of the condensate in pre-heater 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, which represents a 205% increase (more than three times the original baseline of 8.5 MW).

[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 most of this disclosure describe heat integration between a power plant and a chemical synthesis plant that generates waste heat via an exothermic synthesis reaction, it is understood that this disclosure is not limited thereto. For example, as described herein, the plant may run a thermodynamic power cycle without actually generating electricity, although the condensed working fluid (with or without a turbine for generating electricity) still needs to be reheated as part of such a cycle. By way of example, this may be the case, especially 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 the heat as thermal energy. In some parts of the world (e.g., Iceland, Norway, etc.), this may be a ferrosilicon plant or other plant. For example, the waste heat recovery unit may produce steam or other working fluid / heat medium that can be used for CO2 capture, to run compressors, for distillation, for district heating of industrial areas, heating of nearby towns, and / or heating of other industries, such as fish farming, in some of these specific cases, but it is clear that this 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 of the chemical synthesis plant, such that heat integration can 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 the 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 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 a group 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 features disclosed. 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] Although the present disclosure describes specific embodiments and examples of heat integration, it will 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 indicated, numbers expressing quantities, components, distances, or other measurements described herein and in the claims should be understood as being optionally modified by the term "about" or synonyms thereof. Terms such as "about," "approximately," and "substantially," when used in connection with a stated amount, value, or condition, can be interpreted as meaning 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) an ETL (Emission to Liquids) plant (100) that produces heat from an exothermic reaction, comprising: a generator (214) of steam or other working fluid; A turbine (202); A condenser (206) (e.g., a seawater condenser); and A pump (208); 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 second extraction stream (204) is fed to a heat exchanger (150) and heat from the second extraction stream (204) is used to heat a bottom condensate fraction from a distillation column (128) in a reboiler (136) connected to the distillation column (128); The system wherein the heat exchanger (150) returns a cold stream (216) to the water preheater (210) connected to the power cycle of the partner plant (200).

2. The system of claim 1 , wherein the power cycle is used to generate electricity.

3. The system of claim 1 , wherein the power cycle is a power cycle not used to generate electricity.

4. Steam or other working fluid from the power cycle powers machinery and produces CO 2 Recovery of and / or H 2 The system of claim 1 , which is used to generate

5. The system of claim 1 , wherein the first bleed flow is a low pressure bleed flow.

6. The system of claim 1 , wherein the second bleed flow is an intermediate pressure bleed flow.

7. 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) an ETL (Emission to Liquids) plant (100) that produces heat from an exothermic reaction, comprising: A bleed stream (204) taken from the turbine of the power cycle is fed to a heat exchanger (150) for heating a bottom condensate fraction from a distillation column (128) of the ETL plant in a reboiler (136) connected to the distillation column (128), the heat exchanger (150) returning a cold stream (216) to a water preheater (210); a pump (208) feeding a condensed cold stream (218) from the turbine to a heat exchanger (123) configured to heat the cold stream by exchanging heat from the exothermic reaction of the ETL plant (100) with the condensed cold stream (218), and returning a preheated stream (220) to a water preheater (210) for final heating of a working fluid in a steam or other working fluid generator (214) of the power cycle of the partner plant (200).

8. The system of claim 7 , wherein the high temperature stream (220) is a low quality fluid stream, minimizing or reducing the need for the water preheater to use a high quality bleed stream (212) from the turbine.

9. The heat integration system of claim 7 , wherein the bleed flow is a medium pressure bleed flow.

10. Steam or other working fluid from the power cycle may also or alternatively be used to provide heat to a stripper in a carbon recovery unit (110) and / or to generate H 2 The heat integration system of claim 7 , adapted to provide steam or heat to a generating unit (106).

11. An emission-to-liquids (ETL) plant (100), comprising: a first feed stream (102) and a second feed stream (104); Electrolysis (H 2 a generation unit (106); CO 2 A recovery unit (110); At least one compressor (108, 112, 114); A plurality of heat exchangers (116, 120, 122, 146); A reactor (118); and Catchpot (124) and a catch pot overhead fraction (126); A distillation column (128); A condenser (130); a reflux stream (134); and a distillate stream (132) sent to storage; A reboiler (136); and a source of steam or other working fluid, for example from an electric steam generator (152); 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 ETL plant includes:

12. A system for internal heat integration inside a plant, said system for internal heat integration comprising: a reboiler (136) for reheating the bottom condensate fraction from the distillation column (128); A pump (140); first and second heat exchangers (120, 146); the reboiler (136) supplies a cold stream (138) to the pump (140), the pump (140) supplies a cold stream (142) to the first heat exchanger (120); the first heat exchanger (120) is connected to an outlet of a reactor (118) in which an exothermic reaction occurs; a system for internal heat integration, wherein a stream (144) from the outlet of the first heat exchanger (120) is heated to a high temperature relative to the cold stream (142) and then fed to the second heat exchanger (146), which further heats the stream (144) to a desired temperature and then feeds it to the reboiler (136).

13. The system for internal heat integration of claim 12, wherein the plant is an ETL (Emission to Liquids) plant (100).

14. The system for internal heat integration according to claim 12, wherein the exothermic reaction occurring in the reactor (118) is a methanol synthesis reaction.

15. The system for internal heat integration of claim 12 , wherein the second heat exchanger (146) utilizes steam or other working fluid to produce a high temperature output stream (148).

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