CN121773070A - Methods and systems for generating syngas - Google Patents

Methods and systems for generating syngas

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Publication number
CN121773070A
CN121773070A CN202480054312.2A CN202480054312A CN121773070A CN 121773070 A CN121773070 A CN 121773070A CN 202480054312 A CN202480054312 A CN 202480054312A CN 121773070 A CN121773070 A CN 121773070A
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China
Prior art keywords
gas
reverse water
feed
gas shift
heat exchange
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CN202480054312.2A
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Chinese (zh)
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P·E·J·阿伯特
G·C·辛顿
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Johnson Matthey Davy Technologies Ltd
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Johnson Matthey Davy Technologies Ltd
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Priority claimed from GBGB2313695.5A external-priority patent/GB202313695D0/en
Priority claimed from GBGB2403319.3A external-priority patent/GB202403319D0/en
Application filed by Johnson Matthey Davy Technologies Ltd filed Critical Johnson Matthey Davy Technologies Ltd
Publication of CN121773070A publication Critical patent/CN121773070A/en
Pending legal-status Critical Current

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    • C01B3/00—Hydrogen; Gaseous mixtures containing hydrogen; Separation of hydrogen from mixtures containing it; Purification of hydrogen; Reversible storage of hydrogen
    • C01B3/02—Production of hydrogen; Production of gaseous mixtures containing hydrogen
    • C01B3/06—Production of hydrogen; Production of gaseous mixtures containing hydrogen by reaction of inorganic compounds containing electro-positively bound hydrogen with inorganic reducing agents
    • C01B3/12—Production of hydrogen; Production of gaseous mixtures containing hydrogen by reaction of inorganic compounds containing electro-positively bound hydrogen with inorganic reducing agents by reaction of water vapour with carbon monoxide
    • C01B3/16—Production of hydrogen; Production of gaseous mixtures containing hydrogen by reaction of inorganic compounds containing electro-positively bound hydrogen with inorganic reducing agents by reaction of water vapour with carbon monoxide using catalysts
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    • C01B3/00—Hydrogen; Gaseous mixtures containing hydrogen; Separation of hydrogen from mixtures containing it; Purification of hydrogen; Reversible storage of hydrogen
    • C01B3/02—Production of hydrogen; Production of gaseous mixtures containing hydrogen
    • C01B3/32—Production of hydrogen; Production of gaseous mixtures containing hydrogen by reaction of gaseous or liquid organic compounds with gasifying agents, e.g. water, carbon dioxide or air
    • C01B3/34—Production of hydrogen; Production of gaseous mixtures containing hydrogen by reaction of gaseous or liquid organic compounds with gasifying agents, e.g. water, carbon dioxide or air by reaction of hydrocarbons with gasifying agents
    • C01B3/38—Production of hydrogen; Production of gaseous mixtures containing hydrogen by reaction of gaseous or liquid organic compounds with gasifying agents, e.g. water, carbon dioxide or air by reaction of hydrocarbons with gasifying agents using catalysts
    • C01B3/382—Processes with two or more reaction steps, of which at least one is catalytic, e.g. steam reforming and partial oxidation
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
    • C01B3/00—Hydrogen; Gaseous mixtures containing hydrogen; Separation of hydrogen from mixtures containing it; Purification of hydrogen; Reversible storage of hydrogen
    • C01B3/02—Production of hydrogen; Production of gaseous mixtures containing hydrogen
    • C01B3/32—Production of hydrogen; Production of gaseous mixtures containing hydrogen by reaction of gaseous or liquid organic compounds with gasifying agents, e.g. water, carbon dioxide or air
    • C01B3/34—Production of hydrogen; Production of gaseous mixtures containing hydrogen by reaction of gaseous or liquid organic compounds with gasifying agents, e.g. water, carbon dioxide or air by reaction of hydrocarbons with gasifying agents
    • C01B3/38—Production of hydrogen; Production of gaseous mixtures containing hydrogen by reaction of gaseous or liquid organic compounds with gasifying agents, e.g. water, carbon dioxide or air by reaction of hydrocarbons with gasifying agents using catalysts
    • C01B3/384—Production of hydrogen; Production of gaseous mixtures containing hydrogen by reaction of gaseous or liquid organic compounds with gasifying agents, e.g. water, carbon dioxide or air by reaction of hydrocarbons with gasifying agents using catalysts with external heating of the catalyst
    • C—CHEMISTRY; METALLURGY
    • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
    • C10G—CRACKING HYDROCARBON OILS; PRODUCTION OF LIQUID HYDROCARBON MIXTURES, e.g. BY DESTRUCTIVE HYDROGENATION, OLIGOMERISATION, POLYMERISATION; RECOVERY OF HYDROCARBON OILS FROM OIL-SHALE, OIL-SAND, OR GASES; REFINING MIXTURES MAINLY CONSISTING OF HYDROCARBONS; REFORMING OF NAPHTHA; MINERAL WAXES
    • C10G2/00—Production of liquid hydrocarbon mixtures of undefined composition from oxides of carbon
    • C10G2/30—Production of liquid hydrocarbon mixtures of undefined composition from oxides of carbon from carbon monoxide with hydrogen
    • C10G2/32—Production of liquid hydrocarbon mixtures of undefined composition from oxides of carbon from carbon monoxide with hydrogen with the use of catalysts
    • C—CHEMISTRY; METALLURGY
    • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
    • C10K—PURIFYING OR MODIFYING THE CHEMICAL COMPOSITION OF COMBUSTIBLE GASES CONTAINING CARBON MONOXIDE
    • C10K3/00—Modifying the chemical composition of combustible gases containing carbon monoxide to produce an improved fuel, e.g. one of different calorific value, which may be free from carbon monoxide
    • C10K3/02—Modifying the chemical composition of combustible gases containing carbon monoxide to produce an improved fuel, e.g. one of different calorific value, which may be free from carbon monoxide by catalytic treatment
    • C10K3/026—Increasing the carbon monoxide content, e.g. reverse water-gas shift [RWGS]
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    • C01B2203/00—Integrated processes for the production of hydrogen or synthesis gas
    • C01B2203/02—Processes for making hydrogen or synthesis gas
    • C01B2203/0205—Processes for making hydrogen or synthesis gas containing a reforming step
    • C01B2203/0227—Processes for making hydrogen or synthesis gas containing a reforming step containing a catalytic reforming step
    • C01B2203/0233—Processes for making hydrogen or synthesis gas containing a reforming step containing a catalytic reforming step the reforming step being a steam reforming step
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
    • C01B2203/00—Integrated processes for the production of hydrogen or synthesis gas
    • C01B2203/02—Processes for making hydrogen or synthesis gas
    • C01B2203/0205—Processes for making hydrogen or synthesis gas containing a reforming step
    • C01B2203/0227—Processes for making hydrogen or synthesis gas containing a reforming step containing a catalytic reforming step
    • C01B2203/0244—Processes for making hydrogen or synthesis gas containing a reforming step containing a catalytic reforming step the reforming step being an autothermal reforming step, e.g. secondary reforming processes
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    • C01B2203/00—Integrated processes for the production of hydrogen or synthesis gas
    • C01B2203/06—Integration with other chemical processes
    • C01B2203/062—Hydrocarbon production, e.g. Fischer-Tropsch process
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    • C01—INORGANIC CHEMISTRY
    • C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
    • C01B2203/00—Integrated processes for the production of hydrogen or synthesis gas
    • C01B2203/08—Methods of heating or cooling
    • C01B2203/0805—Methods of heating the process for making hydrogen or synthesis gas
    • C01B2203/0833—Heating by indirect heat exchange with hot fluids, other than combustion gases, product gases or non-combustive exothermic reaction product gases
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
    • C01B2203/00—Integrated processes for the production of hydrogen or synthesis gas
    • C01B2203/14—Details of the flowsheet
    • C01B2203/142—At least two reforming, decomposition or partial oxidation steps in series

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  • Organic Chemistry (AREA)
  • Engineering & Computer Science (AREA)
  • Combustion & Propulsion (AREA)
  • Oil, Petroleum & Natural Gas (AREA)
  • Health & Medical Sciences (AREA)
  • General Health & Medical Sciences (AREA)
  • Inorganic Chemistry (AREA)
  • General Chemical & Material Sciences (AREA)
  • Hydrogen, Water And Hydrids (AREA)

Abstract

公开了一种形成合成气的方法，该方法包括：将包含氢气和二氧化碳的第一进料气体供应至包含反向水煤气变换催化剂的反向水煤气变换反应器，其中到该反向水煤气变换反应器的该第一进料气体具有大于0.5的氢气和二氧化碳的组合摩尔分数；加热该第一进料气体；将包含氢气和二氧化碳的已加热的第一进料气体传递通过该反向水煤气变换反应器内的该反向水煤气变换催化剂，以通过将该二氧化碳的至少一部分转化为一氧化碳来形成反向水煤气变换气体料流；将该反向水煤气变换气体料流从该反向水煤气变换反应器传递到包含蒸汽甲烷重整催化剂的热交换后重整器；将包含甲烷和蒸汽的第二进料气体供应至该热交换后重整器，其中到该热交换后重整器的该第二进料气体具有大于0.5的甲烷和水的组合摩尔分数，其中该反向水煤气变换气体料流在该热交换后重整器内加热该第二进料气体，以在已加热的第二进料气体被传递通过该蒸汽甲烷重整催化剂时驱动蒸汽甲烷重整反应，以产生包含一氧化碳和氢气的蒸汽甲烷重整气体料流，并且其中包含一氧化碳和氢气的合成气产物料流离开该热交换后重整器。

A method for forming syngas is disclosed, the method comprising: supplying a first feed gas comprising hydrogen and carbon dioxide to a reverse water-gas shift reactor comprising a reverse water-gas shift catalyst, wherein the first feed gas to the reverse water-gas shift reactor has a combined molar fraction of hydrogen and carbon dioxide greater than 0.5; heating the first feed gas; passing the heated first feed gas comprising hydrogen and carbon dioxide through the reverse water-gas shift catalyst within the reverse water-gas shift reactor to form a reverse water-gas shift gas stream by converting at least a portion of the carbon dioxide into carbon monoxide; and discharging the reverse water-gas shift gas stream from the reverse water-gas shift reactor... A gas shift reactor is passed to a heat exchange post-reformer containing a steam methane reforming catalyst; a second feed gas containing methane and steam is supplied to the heat exchange post-reformer, wherein the second feed gas to the heat exchange post-reformer has a combined molar fraction of methane and water greater than 0.5, wherein the reverse water-gas shift gas stream heats the second feed gas within the heat exchange post-reformer to drive a steam methane reforming reaction as the heated second feed gas is passed through the steam methane reforming catalyst to produce a steam methane reforming gas stream containing carbon monoxide and hydrogen, and a syngas product stream containing carbon monoxide and hydrogen exits the heat exchange post-reformer.

Description

Method and system for forming synthesis gas
Technical Field
The present specification relates to a method and system for forming a synthesis gas (also referred to as synthesis gas) comprising a mixture of hydrogen and carbon monoxide. The present specification also relates to a method and system for producing hydrocarbons from synthesis gas.
Background
A gas stream comprising hydrogen and carbon monoxide (synthesis gas) is used in a process for synthesizing chemicals, including hydrocarbons and oxygenated hydrocarbons, such as alcohols. Typically, the inerts content (CO 2、CH4、N2, etc.) of these synthesis gas streams is optimally low and is produced at a target ratio of H 2/CO, typically in the range of 1.8 to 2.2.
Synthesis gas generation using a Reverse Water Gas Shift (RWGS) reaction may be advantageous because it utilizes carbon dioxide that may have been designated for release into the atmosphere. In addition, hydrogen gas (so-called green hydrogen) for the reverse water gas shift reaction can be produced by water electrolysis using regeneratively produced electricity. Following this synthetic gas generation route and using the synthesis gas to produce hydrocarbons, a fully integrated process can be provided to synthesize green hydrocarbons from carbon dioxide and hydrogen produced by electrolysis of water.
The reverse water gas shift reaction can be described as follows:
H2 + CO2 ⇌ CO + H2O
The reverse water gas shift reaction is endothermic and thus high temperatures favor higher conversion of hydrogen and carbon dioxide to carbon monoxide and water. Various methods for performing RWGS are known in the art, including:
(i) The partial CO 2/H2 feed is combusted with oxygen in the combustor and the hot gas is passed through the RWGS catalyst bed such that the RWGS reaction proceeds adiabatically toward equilibrium.
(Ii) Feed CO 2/H2 is passed through RWGS catalyst in tubes in a furnace and fuel is combusted in the furnace to provide heat for the RWGS reaction.
(Iii) The electrical energy is used to preheat the CO 2/H2 feed upstream of the RWGS catalyst. This may be achieved, for example, by using electrostatic resistive heaters or by directly heating the gas, such as by using Turbo Mechanical Heating (TMH).
(Iv) Resistive heating is provided within the RWGS catalyst.
(V) The CO 2/H2 feed is passed through tubes containing catalyst in a heat exchanger where the tubes are heated by fluid in a secondary heating loop (secondary heating using, for example, electrical energy).
Since high temperatures favor high equilibrium RWGS conversions, the gas exiting the RWGS catalyst is typically at high temperatures, and it would be advantageous to recover high temperature heat from this stream to reduce the primary energy input used in any of the heating processes (i) through (v) listed above.
Another known method for generating synthesis gas is via a steam methane reforming reaction, which is depicted as follows:
CH4 + H2O ⇌ CO + 3H2
The reaction is also endothermic and thus the high temperature favors higher conversion of methane and steam to carbon monoxide and hydrogen.
The synthesis gas produced using the process as described above may be converted to liquid hydrocarbons using a fischer-tropsch process. The fischer-tropsch reaction takes place in the presence of a metal catalyst, typically at a temperature of 150 to 300 ℃ and a pressure of one atmosphere to several tens of atmospheres. The fischer-tropsch process involves a series of chemical reactions which produce various hydrocarbons, desirably of formula (C nH2n+2). More useful reactions produce alkanes as follows:
(2n + 1) H2 + n CO → CnH2n+2 + n H2O
wherein n may be 1 to 100 or higher. The formation of methane (n=1) is undesirable. In addition to the formation of alkanes, competing reactions also produce small amounts of olefins, alcohols and other oxygenated hydrocarbons. The Fischer-Tropsch reaction is highly exothermic due to the standard enthalpy of reaction (. DELTA.H) of-165 kJ/mol combined CO.
WO2022079408 describes a reverse water gas shift process for producing a gas stream comprising carbon monoxide by feeding a gas mixture comprising carbon dioxide and hydrogen to a burner provided in a reverse water gas shift reactor and combusting it with a sub-stoichiometric amount of an oxygen stream to form a combustion gas mixture comprising carbon monoxide, carbon dioxide, hydrogen and steam. The mixture is then passed through a reverse water gas shift catalyst to form a crude product gas comprising carbon monoxide, carbon dioxide, hydrogen and steam. The gas is then cooled so that the moisture condenses and can be separated and removed. The gas stream is then passed to a carbon dioxide removal unit to remove carbon dioxide, which may be recycled to the feed gas mixture to the reverse water gas shift reactor and produce a synthesis gas comprising carbon monoxide and hydrogen.
WO2022079408 also describes a process for the synthesis of hydrocarbons in which at least a portion of the H 2/CO-containing gas from the RWGS process as described above is fed to a fischer-tropsch (FT) unit to produce hydrocarbons and FT water. At least a portion of the water can be recycled back to the electrolysis unit that feeds hydrogen to the RWGS reactor. It is also described that a gas mixture comprising methane and carbon dioxide formed by pre-reforming the Fischer-Tropsch tail gas (or "off-gas") and optionally non-condensable hydrocarbons recovered from the downstream Fischer-Tropsch process may be recycled and fed to the reverse water gas shift reactor.
WO2022079098 describes an apparatus for the synthesis of hydrocarbons from hydrogen and carbon dioxide comprising an electrically heated water gas shift section (e-RWGS). This is illustrated by the use of a structured catalyst comprising a macrostructure of electrically conductive material capable of catalyzing reverse water gas shift reactions, methanation reactions and steam reforming reactions.
WO2022253965 describes a system comprising a RWGS reactor and a Heat Exchange Reactor (HER), wherein a feed comprising hydrogen and carbon dioxide is fed to each reactor. At least a portion of the RWGS shifted gas exiting the first reactor is fed to the heating side of the HER, allowing further RWGS to occur in the reactor, producing a second product gas comprising CO. A small amount of methane-containing gas may also be fed to the first and/or second hydrogen/carbon dioxide feeds.
WO2022253965 also discloses a method of carrying out RWGS on the process (tube) side of HER, wherein the main reactions in the first part of the tube (closest to the inlet) are CO 2 and methanation of CO to methane (and RWGS), and the main reaction in the second part of the tube is steam reforming of methane to CO/CO 2 (and RWGS). The stated advantage of this method is that the temperature rises rapidly in the first part of the tube, so that carbon formation on the catalyst (by CO reduction or Boudouard reaction) is not favored. However, a disadvantage of conducting RWGS in HER in this way is that it limits the amount of heat recovery that can be achieved in the reactor, so that generally more primary heating (from an external source) will be required.
The present description relates to providing an improved method and system for generating syngas, and in particular a more efficient method and system from a thermal management point of view.
Disclosure of Invention
The present specification provides a method of forming synthesis gas, the method comprising:
Supplying a first feed gas comprising hydrogen and carbon dioxide to a reverse water gas shift reactor comprising a reverse water gas shift catalyst, wherein the first feed gas to the reverse water gas shift reactor has a combined mole fraction of hydrogen and carbon dioxide of greater than 0.5 (optionally greater than 0.6, 0.7, 0.8, 0.9, or 0.95);
heating the first feed gas;
Passing a heated first feed gas comprising hydrogen and carbon dioxide through the reverse water gas shift catalyst within the reverse water gas shift reactor to form a reverse water gas shift gas stream by converting at least a portion of the carbon dioxide to carbon monoxide;
Passing the reverse water gas shift gas stream from the reverse water gas shift reactor to a heat exchange post reformer comprising a steam methane reforming catalyst;
Supplying a second feed gas comprising methane and steam to the heat exchange post-reformer, wherein the second feed gas to the heat exchange post-reformer has a combined mole fraction of methane and water of greater than 0.5 (optionally greater than 0.6, 0.7, or 0.8),
Wherein the reverse water gas shift gas stream heats the second feed gas in the post heat exchange reformer to drive a steam methane reforming reaction when the heated second feed gas is passed over the steam methane reforming catalyst to produce a steam methane reformed gas stream comprising carbon monoxide and hydrogen, and
Wherein a synthesis gas product stream comprising carbon monoxide and hydrogen leaves the heat exchange post-reformer.
The first feed gas to the reverse water gas shift reaction consists of or at least comprises mainly carbon dioxide and hydrogen, but may have minor amounts of other components such as methane, carbon monoxide and nitrogen. To reflect the nature of the feed composition, the catalyst in the reverse water gas shift reactor is selected to drive at least predominantly the reverse water gas shift reaction. The second feed gas to the post heat exchange reformer is comprised of or at least contains primarily methane and steam (water), but may have minor amounts of other components such as higher hydrocarbons, carbon dioxide, carbon monoxide, hydrogen and nitrogen. To reflect the nature of the feed composition, the catalyst in the post heat exchange reformer is selected to drive at least primarily the steam methane reforming reaction. The second feed gas may have a mole fraction of methane that is higher than one or more of the mole fraction of carbon dioxide, the mole fraction of hydrogen, or the combined mole fraction of carbon dioxide and hydrogen in the second feed gas. The second feed gas comprising methane and steam may be formed at least in part from one or more of a gas purged from the downstream hydrocarbon synthesis step and optionally enriched back, a naphtha or LPG stream, optionally enriched back, separated from the downstream hydrocarbon synthesis product stream, a biogenic feed source (biogas), and natural gas. Although the second feed gas to the post heat exchange reformer contains mainly methane and steam (water), some carbon dioxide may be added to the second feed gas and this may have some advantages in reducing metal dusting. For example, the second feed gas to the post heat exchange reformer may comprise a carbon dioxide content of at least 10 mole%, 15 mole%, 20 mole%, or 25 mole%, no more than 40 mole%, 35 mole%, or 30 mole%, or within a range defined by any combination of the above lower and upper limits.
This differs from the process disclosed in WO2022253965 in that the feed gas to the reverse water gas shift reactor and the feed gas to the Heat Exchange Reformer (HER) consist essentially of carbon dioxide and hydrogen, with a small amount of methane in either or both of the feeds being optional. In WO2022253965, the catalysts in the reverse water gas shift reactor and the heat exchange reformer are selected to drive at least predominantly the water gas shift reaction to reflect the nature of the CO 2/H2 feed gas to both reactors. This is in contrast to the process of the present specification, wherein a predominantly methane/steam feed stream is provided to a heat exchanged post-reformer comprising a steam-methane reforming catalyst to drive a steam methane reforming reaction, and a hot gas stream from the RWGS reactor is utilized to drive the steam methane reforming reaction downstream of the RWGS reactor. It has been found that the present process is more thermally efficient and is capable of recovering more high temperature heat than heat exchange recovery in existing configurations that utilize CO-feed of H 2 and CO 2 to both the RWGS reactor and the HER reactor, requiring that the RWGS catalyst inlet to the HER be subjected to methanation exotherms to prevent carbon formation on the RWGS catalyst in the HER. The method achieves more efficient use of the primary heat source. A comparison of the two methods is given in the detailed description, indicating that the present method allows an increase in the amount of recovered heat by >2x and a reduction in the required heat input by about 27%.
Depending on the configuration of the post heat exchange reformer, the reverse water gas shift gas stream may be mixed with the steam methane reformed gas stream within the post heat exchange reformer such that the synthesis gas product stream exiting the post heat exchange reformer comprises a mixture of the reverse water gas shift gas stream and the steam methane reformed gas stream. Alternatively, the reverse water gas shift gas stream may be maintained separate from (but thermally coupled to) the steam methane reformed gas stream within the heat exchange post-reformer, in which case two separate synthesis gas product streams leave the heat exchange post-reformer, one formed from the reverse water gas shift gas stream and one formed from the steam methane reformed gas stream. These separate synthesis gas streams may be subsequently combined.
The first feed gas is heated prior to entering the reverse water gas shift reactor and/or the first feed gas is heated within the reverse water gas shift reactor. The first feed gas may be heated by one or more of a turbo-mechanical heater that directly heats the first feed gas prior to entering the reverse water gas shift reactor, a turbo-mechanical heater that heats a heat transfer fluid that then heats the first feed gas prior to entering the reverse water gas shift reactor or within the reverse water gas shift reactor, an electrical heating system that operates prior to entering the reverse water gas shift reactor or within the reverse water gas shift reactor, one or more heat exchangers that operate prior to entering the reverse water gas shift reactor, and combusting oxygen and hydrogen within the reverse water gas shift reactor that is an autothermal reformer.
In certain configurations, at least a portion of the synthesis gas product stream from the heat exchange post-reformer may be fed through the autothermal reformer to increase the CO content. For example, when the heat exchanged post-reformer is configured to produce two separate syngas product streams, one formed from the reverse water gas shift gas stream and one formed from the steam methane reformed gas stream, the syngas product stream formed from the steam methane reformed gas stream may be fed through the autothermal reformer prior to mixing with the syngas product stream formed from the reverse water gas shift gas stream.
The present specification also provides a process for producing hydrocarbons comprising forming synthesis gas as described above and passing the synthesis gas through a Fischer-Tropsch reactor to produce hydrocarbons. In this regard, the synthesis gas produced by the reverse water gas shift reactor and the heat exchanged post reformer may be utilized to produce hydrocarbon products via a Fischer Tropsch process. In addition to producing the desired hydrocarbon products, the Fischer-Tropsch process also produces tail gas (or "off gas"), which may be recycled and used, at least in part, as an input feed gas to the post heat exchange reformer. Optionally, downstream processing of the hydrocarbon product, such as hydrotreating/hydrocracking, may be performed. This increases the product value but may also produce a less valuable naphtha stream. Such naphtha streams may also be recycled and used at least in part as input feed gas to the heat exchange post-reformer. These recycle streams may be subjected to reverse enrichment in one or more reverse enrichment reactors to produce a methane-containing stream for input to the post heat exchange reformer. This is in contrast to the configuration disclosed in WO2022079408, wherein the gas mixture comprising methane and carbon dioxide formed by pre-reforming the fischer-tropsch tail gas and optionally non-condensable hydrocarbons recovered from the downstream fischer-tropsch process is recycled and fed to the reverse water gas shift reactor, rather than to the heat exchanged post-reformer heated by the reverse water gas shift reactor product stream.
The present specification also provides a system for performing a method as described herein, the system comprising:
A first feed gas supply unit configured to supply a first feed gas comprising hydrogen and carbon dioxide to a reverse water gas shift reactor, wherein the first feed gas supply unit is configured to supply the first feed gas with a combined mole fraction of hydrogen and carbon dioxide of greater than 0.5 to the reverse water gas shift reactor;
A heating unit configured to heat the first feed gas;
A reverse water gas shift reactor comprising a reverse water gas shift catalyst, the reverse water gas shift reactor configured to receive the first feed gas, pass the first feed gas through the reverse water gas shift catalyst to form a reverse water gas shift gas stream, and pass the reverse water gas shift gas stream from the reverse water gas shift reactor to a post heat exchange reformer;
A second feed gas supply unit configured to supply a second feed gas comprising methane and steam to the heat exchange post-reformer, wherein a combined mole fraction of methane and water is greater than 0.5, and
A heat exchange post-reformer comprising a steam methane reforming catalyst, the heat exchange post-reformer configured to receive the second feed gas and pass the second feed gas through the steam methane reforming catalyst, the heat exchange post-reformer further configured to receive the reverse water gas shift gas stream and provide a heat exchange from the reverse water gas shift gas stream to the second feed gas to heat the second feed gas and drive a steam methane reforming reaction to produce a steam methane reforming gas stream comprising carbon monoxide and hydrogen as the heated second feed gas is passed through the steam methane reforming catalyst, the heat exchange post-reformer thereby producing a synthesis gas product stream comprising carbon monoxide and hydrogen.
The system may also include a Fischer-Tropsch unit comprising a Fischer-Tropsch catalyst configured to receive the synthesis gas product stream and to pass the synthesis gas product stream through the Fischer-Tropsch catalyst to produce a hydrocarbon product stream.
Several different examples of heating, reactors and flow sheet configurations are set forth in the figures and detailed description.
Drawings
FIG. 1 shows a flow chart of a method of forming synthesis gas using a reverse water gas shift reactor followed by a post heat exchange reformer.
FIG. 2 shows a flow chart of a process for forming a hydrocarbon product stream by combining the synthesis gas formation process of FIG. 1 with a Fischer-Tropsch unit.
Fig. 3 shows a more detailed flow chart of a method of forming a hydrocarbon product stream.
Fig. 4 (a) to 4 (c) show examples of configurations of the reformer after heat exchange.
FIG. 5 shows a flow chart of a method of forming a hydrocarbon product stream using a turbo-mechanical heater to heat a feed gas to a reverse water gas shift reactor.
FIG. 6 shows a flow chart of a method of forming a hydrocarbon product stream using micro-resistance heating for a reverse water gas shift reactor (e-RWGS).
FIG. 7 shows a flow chart of a method for forming a hydrocarbon product stream using a turbo-mechanical heater to heat a heat transfer gas for heating a reverse water gas shift reactor.
Fig. 8 shows a flow chart of a method of forming a hydrocarbon product stream using an autothermal reactor (ATR) as a reverse water gas shift reactor.
Fig. 9 shows a flow chart of a method of forming a hydrocarbon product stream using an autothermal reactor (ATR) downstream of a post heat exchange reformer.
Fig. 10 shows a flow diagram (not according to the present description) in which a gas mixture comprising H 2、CO2, flue gas and steam is fed to a reverse water gas shift reactor and a heat exchange reactor heated by the reverse water gas shift gas.
Fig. 11 shows a temperature profile of a heat exchange reactor using the configuration illustrated in fig. 10.
Fig. 12 shows a flow diagram according to the present description, wherein a gas mixture comprising H 2 and CO 2 is fed to a reverse water gas shift reactor and a gas mixture comprising flue gas and steam is fed to a heat exchange reactor heated by the reverse water gas shift gas.
Fig. 13 shows a temperature profile of a heat exchange reactor using the configuration illustrated in fig. 12, noting that the shell side gas can be further cooled compared to the configurations of fig. 10 and 11, and this allows an increase in the amount of recovered heat by >2x, and a reduction in the required heat input by about 27%.
Fig. 14 shows a flow chart in which an additional raw material of raw biogas is fed to the after heat exchange reformer together with exhaust gas and steam.
Fig. 15 shows a flow diagram in which both naphtha and offgas are fed to a post heat exchange reformer via two separate anti-enrichment reactors.
An overview of the reference numbers used in the figures are listed in the following table.
Detailed Description
FIG. 1 illustrates the basic steps in a process for forming synthesis gas according to the present description. The method comprises supplying a first feed gas 2 comprising hydrogen and carbon dioxide to a reverse water gas shift reactor 4 comprising a reverse water gas shift catalyst. The first feed gas 2 may be provided as a gas mixture of hydrogen and carbon dioxide or as separate hydrogen and carbon dioxide feed streams.
The first feed gas 2 is heated. This heating of the feed gas 2 may be performed before the feed gas enters the reverse water gas shift reactor 4 and/or within the reverse water gas shift reactor 4.
The heated first feed gas 2 comprising hydrogen and carbon dioxide is passed through a reverse water gas shift catalyst within a reverse water gas shift reactor 4 to form a reverse water gas shift gas stream 6 by converting at least a portion of the carbon dioxide to carbon monoxide. The reverse water gas shift gas stream 6 is then passed from the reverse water gas shift reactor 4 to a heat exchange post reformer 10 containing a steam methane reforming catalyst.
The second feed gas 8 comprising methane and steam is fed to a heat exchanged post reformer 10. The second feed gas 8 has a mole fraction of methane that is higher than one or more of the mole fraction of carbon dioxide, the mole fraction of hydrogen, and the combined mole fraction of carbon dioxide and hydrogen. That is, the second feed gas 8 is primarily methane/steam feed gas as compared to the first feed gas 2, which is primarily carbon dioxide/hydrogen feed gas.
The reverse water gas shift gas stream 6 heats the second feed gas 8 in the post heat exchange reformer 10 to drive a steam methane reforming reaction when the heated second feed gas 8 is passed over a steam methane reforming catalyst to produce a steam methane reformed gas stream comprising carbon monoxide and hydrogen.
Finally, a synthesis gas product stream 12 comprising carbon monoxide and hydrogen exits the heat exchanged post reformer 10. The synthesis gas product stream 12 may be formed from a mixture of a reverse water gas shift gas stream and a steam methane reformed gas stream. Alternatively, two synthesis gas product streams 12 may leave the post heat exchange reformer 10, one corresponding to the reverse water gas shift gas stream and one corresponding to the steam methane reformed gas stream. This will depend on the internal configuration of the post heat exchange reformer 10 and whether the two streams are mixed or remain as separate (but thermally coupled) streams within the post heat exchange reformer 10. Examples of different heat exchanged reformer configurations for these options are given later.
The synthesis gas produced by the reverse water gas shift reactor and the heat exchanged post reformer may be utilized to produce hydrocarbon products via a fischer-tropsch process. FIG. 2 shows a flow chart of a process for forming a hydrocarbon product stream by combining the synthesis gas formation process of FIG. 1 with a Fischer-Tropsch unit. The synthesis gas generation section is as described in relation to fig. 1 and will therefore not be repeated (like reference numerals are used for like components). The synthesis gas product stream 12 is passed to a fischer-tropsch reactor 14 comprising a fischer-tropsch catalyst to produce a hydrocarbon product stream 16. Typically, the synthesis gas from the heat exchanged post reformer will be passed through a water removal unit and a carbon dioxide removal unit and optionally further purification steps are performed to remove other impurities that may poison the fischer-tropsch catalyst before being passed into the fischer-tropsch reactor 14.
In addition to producing the desired hydrocarbon product, the Fischer-Tropsch process also produces a tail gas 18, which may be recycled, mixed with steam 19 and used at least in part as an input feed gas to the post heat exchange reformer 10. Optionally, the Fischer-Tropsch product may be further reacted/upgraded. Other less desirable fractions from the downstream upgraded hydrocarbon product stream, such as naphtha, may also be recycled and used at least in part as input feed gas to the post heat exchange reformer 10. These recycle streams may be subjected to reverse enrichment in one or more reverse enrichment reactors 20 to produce a methane-containing stream 22 for input to the post heat exchange reformer 10.
FIG. 3 shows a more detailed flow diagram of a combined process of forming synthesis gas and using the synthesis gas to produce a hydrocarbon product stream.
A pressurized hydrogen stream 30 (e.g., renewable hydrogen from a pressurized electrolysis unit) is introduced into the process. Carbon dioxide stream 32 is also introduced, compressed if necessary (and optionally purified to remove compounds that poison the catalyst, such as sulfur compounds). A portion of the CO 2 stream is directed to the plant. Another portion of the CO 2 stream 34 can be separated from the cooled dehydrated downstream syngas and recycled back to the RWGS unit.
The CO 2 and hydrogen streams 30, 32, 34 are mixed together and then fed to a reactor 40 containing RWGS catalyst to obtain the RWGS shift product. The RWGS equilibrium temperature of the gas at the outlet of the catalyst is at least 750 ℃, preferably at least 800 ℃, more preferably at least 850 ℃, even more preferably at least 900 ℃, and still even more preferably 950 ℃. The heat may be provided to the reactor feeds only (H 2 and CO 2, either alone or together), in which case the RWGS reactor is adiabatic, or to the gases and catalyst in the RWGS reactor only, or to each in part. In the flow diagram illustrated in FIG. 3, the feed gas is heated by a feed exchanger 36 and a preheater 38 before passing into the RWGS reactor 40. As described in the background section, further heating may be provided within the RWGS reactor via combustion with oxygen or via electrical heating within the reactor.
Separately, the methane-containing gas stream is mixed with steam and fed to the tube (process) side of the post heat exchange reformer (HEPR) at a temperature typically between 350 ℃ and 500 ℃. The methane/steam gas feed may be generated by mixing an exhaust gas and/or naphtha gas stream 44 from a downstream FT synthesis unit with HP steam 46, heating the mixture in exchanger 48, and passing the gas mixture through an anti-enrichment reactor 50. In some arrangements of the recycle exhaust stream and the naphtha stream, two separate anti-enrichment reactors may be provided and the resulting methane-containing streams combined and fed into HEPR.
The methane/steam-containing gas passes through the tubes in HEPR in countercurrent to the hot RWGS shift product stream gas flowing on the heated side from RWGS reactor 40, with the methane/steam gas absorbing heat as the endothermic steam reforming reaction proceeds to produce a steam methane reformed gas comprising carbon monoxide and hydrogen. The tubes may be open ended at the outlet such that heated reformate gas passes into the heated side of HEPR a. The RWGS shift product stream is fed to the heated (shell) side of the post-heat exchange reformer 42 where it provides heat for the steam methane reforming reaction and is mixed with the heated reformed gas and cooled as it flows through the shell, thereby transferring the heat to the process side, leaving the shell outlet as a CO-rich product.
The CO-rich product is cooled in stages. Such cooling may be used to generate steam 52 (as used in the process and optionally output) and preheat the feed stream via exchanger 53. Further cooling is required to condense and separate moisture from the gas 55. The gas is then fed to a CO 2 removal unit 54, where unreacted CO 2 is separated 56 and may be recycled upstream 34 of the RWGS unit such that the remaining syngas is essentially H 2/CO syngas.
The H 2/CO synthesis gas may be purified (to remove FT catalyst poisons) and optionally compressed prior to delivery to a Fischer-Tropsch (FT) or other liquid hydrocarbon synthesis unit 58. This produces a hydrocarbon rich off-gas stream 64 and FT water in addition to FT liquid 60. If the electrolysis unit is used locally to provide a renewable hydrogen feed, the latter water stream may (optionally purified and) be recycled and provided as feed to the electrolysis unit. The exhaust gas 64 may be recycled to the upstream 44 of the post heat exchange reformer to produce or facilitate a methane-containing feed to the post heat exchange reformer. Liquid hydrocarbon production may also produce an over-demand naphtha stream 62 as a product, and it may also be recycled to the upstream 44 of the post heat exchange reformer to produce or contribute to the methane-containing feed to the post heat exchange reformer.
HEPR are possible, all of which use RWGS shift streams to provide heat for endothermic steam reforming, and are shown in fig. 4 (a) to 4 (c).
The configuration illustrated in fig. 4 (a) is the same as that shown in fig. 3. The H 2/CO2 feed gas is heated in the preheater 72 and passed to the reverse water gas shift reactor 74. The resulting reverse water gas shift gas 76 is fed to a heat exchanged post reformer 78. The post heat exchange reformer 78 includes a housing and a plurality of open ended tubes including a steam methane reforming catalyst. Methane/steam feed gas 80 is fed through the tubes, while reverse water gas shift gas 76 is fed to the shell side of heat exchange post-reformer 78, and the methane/steam feed gas 80 is heated and steam methane reforming reactions occur as it passes through the catalyst material in the tubes. The steam methane reformed gas exits the tubes at the open ends of the tubes and mixes with the reverse water gas shift gas in the shell side of HEPR. The mixed CO-rich syngas product stream 82 then exits the shell side of HEPR. Thus, this configuration HEPR produces a single synthesis gas product stream formed from the mixture of reverse water gas shift gas and steam methane reformed gas.
Fig. 4 (b) shows an alternative HEPR configuration in which the reverse water gas shift gas and steam methane reformed gas are not mixed within HEPR, but rather leave HEPR as separate CO-rich product streams. HEPR includes a plurality of tubes including steam methane reforming catalyst material and surrounding shell side. However, the flow path through the tube remains separate from the flow path through the shell side of HEPR. The illustrated design has two tube sheets that are used to keep the two flow paths separate. The reverse water gas shift gas 76 is passed through the shell side of HEPR to 78. The methane/steam feed gas 80 is fed through a plurality of tubes containing a steam methane reforming catalyst. The heating for the endothermic reforming within the tubes is provided by cooling the RWGS shift stream around the outer surfaces of the tubes. Two CO-rich products are produced, the first being the heated reformate gas 82 (i) and the second being the cooled RWGS shift stream 82 (ii). The first CO-rich product 82 (i) can optionally be added to the feed to the RWGS to enable further conversion of residual methane and CO2 in the stream.
Fig. 4 (c) shows another HEPR design 78 with one tube sheet and using bayonet tubes. Methane-containing gas and steam 80 passes downwardly through the catalyst-filled annular space to absorb heat from the shell side reverse water gas shift gas 76 and the center bayonet tube. The heated reformed gas exits and then passes back up the central tube, releasing heat to the process gas in the annular tube. Heating for endothermic reforming is provided by the cooled RWGS shift stream. Two CO-rich products are produced, the first being a cooled RWGS shift stream 82 (i) and the second being a cooled reformate gas 82 (ii). The two products may be mixed together downstream to form a single H 2/CO synthesis gas stream for delivery to hydrocarbon synthesis.
It should be noted that within HEPR, the methane/steam feed is passed through the steam methane reforming catalyst, while the reverse water gas shift gas stream from the reverse water gas shift reactor is not passed through the steam methane reforming catalyst.
Various options may be utilized to provide heat for the RWGS reaction. Fig. 5-9 illustrate a flow diagram configuration similar to that illustrated in fig. 3, but with different options for providing heat for the RWGS reaction. Like parts are denoted by like reference numerals, and a repeated description of the complete flowchart is not repeated for the sake of brevity.
An alternative to electrical heating is static electrical heating or "turbo-mechanical heating" (TMH) of the H 2 and CO 2 feeds to the RWGS reactor.
For example, electrostatic heating may be achieved by passing the feed gas through a tube in an electric furnace equipped with an electrically heated radiant panel. Alternatively, the feed gas may be heated in a heat exchanger comprising one or more resistive heating elements (enclosed in an insulating sheath).
The term "turbo-mechanical heating" means utilizing an apparatus that imparts kinetic energy to the gas to heat the gas through a rotatable shaft assembly-this is schematically illustrated in fig. 5, wherein the H 2 and CO 2 feeds pass through a turbo-mechanical heater 90 to heat the feed gas prior to entering the RWGS reactor 40. In this configuration, the H 2 and CO 2 feed gases are directly heated by the turbo-mechanical heater.
Alternatively, micro-resistive in situ heating of the catalyst and flowing gas inside the RWGS reactor may be utilized. The electrical energy is directly converted to heat in the RWGS catalyst. This is shown in fig. 6, which includes an electrically heated reverse water gas shift reactor (e-RWGS 92), and which provides heat to the RWGS by in situ resistive heating of the RWGS catalyst.
Combustion of hydrocarbon-containing gas/fossil fuel with oxygen-containing gas is another heating method. In one embodiment, heating may be accomplished by passing the feed gas through a tube within an atmospheric burner. Any fuel may be used, but it is clear that a fuel with low temperature gaseous (GHG) warming potential would be preferred if the carbon strength of the downstream product were to be minimized. One such fuel is biogas.
Fig. 7 shows yet another alternative for heating the reverse water gas shift reaction (and subsequently providing heat to the heat exchanged post-reformer). This configuration uses either turbo-mechanical heating 100 or static electrical heating of the heat transfer fluid, whereby the fluid can be used to indirectly provide heat to the RWGS reactor 40. The heat transfer fluid flows on the heated side of the RWGS heat exchange reactor where RWGS occurs on the process side (i.e., tubes in which the RWGS catalyst is disposed). In the illustrated embodiment, the heat transfer fluid is provided by CO 2 gas 96, which CO 2 gas is transferred to buffer 98 before being heated in the turbomachine heater 100. The heated gas then flows through the shell side of the heat exchange RWGS reactor 40, exchanging heat with the CO 2/H2 process gas within the tube side of the RWGS reactor. The heat transfer gas is then returned to the buffer 98 and recirculated through the turbo-mechanical heater 100. Thus, FIG. 7 illustrates an option for turbomachinery heating using a heat transfer fluid, which indirectly provides heat to the RWGS reaction.
FIG. 8 shows another option for providing heat for the reverse water gas shift reaction by internal combustion of oxygen 104 (sub-stoichiometric) with hydrogen in the H 2/CO2 stream and subsequent transfer of high temperature gas through an adiabatic RWGS bed. This is known as autothermal reforming (ATR), and thus the reverse water gas shift reactor is the ATR RWGS reactor 102. Thus, fig. 8 shows the option of providing RWGS by internal combustion using ATR.
Another possible embodiment, particularly suitable for the HEPR design shown in fig. 4 (b) and 4 (c), is to feed the second CO-rich gas to an autothermal reformer (ATR 106), as shown in fig. 9. The ATR consists of an oxygen burner upstream of an adiabatic steam reforming catalyst bed. Thus, the ATR 106 increases the temperature at which the second CO-rich gas is at RWGS equilibrium and is therefore converted to CO at the expense of a partial loss of hydrogen in the gas. Thus, fig. 9 shows the option of feeding one of the CO-rich gas streams from HEPR (i.e., the steam methane reformed gas stream) to an oxygen-fired autothermal reformer (ATR). The resulting gas stream having increased CO content may then be combined with another CO-rich gas stream from HEPR (i.e., a reverse water gas shift gas stream).
There are many possible sources of methane-containing gas. Examples include the following:
(i) The gas purged from downstream hydrocarbon synthesis steps, such as FT synthesis ("tail gas" or "off gas"), contains methane and light hydrocarbons. It may be recycled back so that it can be steam reformed to produce CO and H 2. Depending on the composition, it may be beneficial to first reverse enrich (pre-reform) the gas to form a methane-containing gas to feed HEPR.
(Ii) A light naphtha or LPG stream may be separated from the hydrocarbon synthesis product in a downstream upgrading step. The product may be recycled back for de-enrichment and steam reforming. It may be beneficial to treat this light naphtha or LPG stream in a de-enrichment vessel separate from the off-gas in order to optimize the de-enrichment conditions of the different recycle streams and produce methane-containing gas for HEPR.
(Iii) A light naphtha or LPG stream or exhaust gas, which is a byproduct of another process for converting vegetable oil to renewable diesel (RND) or Sustainable Aircraft Fuel (SAF), can be fed to a de-enrichment reactor to produce a renewable source of methane-containing gas.
(Iv) Another potential biogenic feed stream is biogas, such as that produced in landfill gas facilities or Anaerobic Digestion (AD) facilities. After purification, the composition is typically 40% to 60% CO 2 and 40% to 60% CH 4. It may be added as a raw material to HEPR. This is advantageous for generating additional hydrogen from a biogenic feed source while providing a biogenic CO 2 feed, which would enable the use of less hydrogen (from renewable sources).
Another embodiment is to feed a portion (up to 10%) of the CO 2 feedstock directly to HEPR with the methane-containing gas feed, in which case less CO 2 is required in the combined H 2/CO2 feed to the RWGS reactor to achieve the desired target total syngas H 2/CO ratio. This may be advantageous in order to increase the amount of high level heat recovered in HEPR and further reduce the external heating load.
It will also be appreciated that small amounts of hydrogen may advantageously be added directly to HEPR with the methane-containing gas feed. The purpose of this addition may be to chemically assist in feedstock purification or conditioning of the catalyst (such as an anti-enrichment catalyst) and is typically present at a level of <5% of any methane-containing gas, rather than to promote the RWGS reaction in HEPR.
Another option is to add the methane-containing stream to the RWGS reactor with H 2/CO2. The case of this process may be if it is desired to feed a large amount of the methane-containing stream through the system (as compared to the H 2/CO2 stream). In this case, the amount of methane can be higher than that which can usefully be steam reformed in HEPR heated by the RWGS shift gas. Thus, in this case, methane can be split, with a portion being passed through the RWGS reactor with the H 2/CO2 feed stream and the remainder being fed through HEPR.
Examples of calculations are provided below. All examples were calculated to give a combined gas containing about 3200 kgmols/hour of H 2/CO in a ratio of 2.14 in a synthesis gas containing the same amount of methane and to utilize the same amount and composition of off-gas recycled from the downstream fischer-tropsch process.
Figure 10 shows a schematic not according to the present specification, where H 2 and CO 2, exhaust gas and steam are fed to both the RWGS reactor and HER heated by the RWGS shift gas. External heating for the RWGS may be provided upstream or internally of the RWGS. This corresponds to the method described in WO2022253965 discussed in the background section of the present specification. That is, rather than providing a stream containing primarily methane to the post heat exchange reformer to substantially steam methane reform in the post heat exchange reformer, the feed to both the RWGS reactor and the heat exchange reformer is primarily H 2 and CO 2, containing only small amounts of methane and steam. The combined H 2/CO2/off-gas/steam split, 78% of which entered RWGS and 22% passed to the process side of HER, the mass balance of comparative example 1 is shown in the table below.
In this process, the gas fed to the HER undergoes exothermic methanation reactions in a first part of the process side heated to >700 ℃. This limits the amount of recovered heat that can be recovered, allowing only the shell side gas to cool to about 750 ℃, as shown in fig. 11, which illustrates a temperature profile in HER.
In contrast to the above, fig. 12 shows a schematic according to the present specification, where H 2 and CO 2 are fed to the RWGS reactor and the exhaust gas/steam is fed to HEPR heated by the RWGS shift gas. External heating for the RWGS may be provided upstream or internally of the RWGS. In this example, the same amount of feed H 2 was used as in the previously discussed comparative example. The mass balance of this example 2 is shown in the table below, where the feed to the RWGS reactor is mainly CO 2/H2 and the feed to HEPR is mainly methane/steam (H 2 O).
In this embodiment, the shell side gas may be further cooled to about 590 ℃, as shown in fig. 13. This allows for an increase in the amount of recovered heat by more than a factor of two (> 2 x) compared to the comparative examples previously discussed, and a reduction in the required heat input of about 27%.
Fig. 14 shows a schematic of example 3, where there is an additional feed of raw biogas 108 containing about 50% methane and about 50% CO 2, which is fed to HEPR with flue gas and steam. As in the previous examples, all of the H 2/CO2 feed was fed to the RWGS reactor. The mass balance of this example is shown in the table below, where the feed to the RWGS reactor is primarily CO 2/H2 and the feed to HEPR is still primarily methane/steam (H 2 O), although the level of CO 2 is increased compared to the previous example.
In this example, the addition of about 3tes/hr of biogas allows the feed hydrogen to be reduced by about 7% using the mass balance shown above. The shell side gas may be cooled further to about 525 ℃ than in the previous embodiment. This allows a further increase in the amount of heat recovered compared to the previous embodiments, and a reduction in the required heat input of about 4%.
Another embodiment (embodiment 4) is shown in fig. 15. There is an additional feed to naphtha 110 that may be formed as a byproduct in the FT product upgrading and that is not available as a fuel product. Naphtha feeds contain primarily alkanes in the C4 to C7 range. In this arrangement, the naphtha is heated in naphtha exchanger 112 and the naphtha is back-enriched in naphtha back-enrichment reactor 114 before being fed to HEPR, 42. In this embodiment, the exhaust gas 44 is heated separately in the exhaust gas exchanger 118 and is back-enriched in the exhaust gas back-enrichment reactor 120 before being fed to HEPR 42.
As in the previous examples, all of the H 2/CO2 feed was fed to the RWGS reactor. The mass balance of example 4 is shown in the table below.
In this example, with the mass balance shown, the addition of about 1.65tes/hr of naphtha allowed for a 13% to 14% reduction in feed hydrogen (as compared to example 2). The shell side gas may be cooled further to about 490 ℃ than in example 2. This allows a further increase in the amount of heat recovered compared to example 2, and a reduction in the required heat input of about 2%.
While the present invention has been particularly shown and described with reference to certain examples, it will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the scope of the invention as defined by the appended claims.

Claims (14)

1.一种形成合成气的方法，所述方法包括：1. A method for forming syngas, the method comprising: 将包含氢气和二氧化碳的第一进料气体供应至包含反向水煤气变换催化剂的反向水煤气变换反应器，其中到所述反向水煤气变换反应器的所述第一进料气体具有大于0.5的氢气和二氧化碳的组合摩尔分数；A first feed gas containing hydrogen and carbon dioxide is supplied to a reverse water-gas shift reactor containing a reverse water-gas shift catalyst, wherein the first feed gas to the reverse water-gas shift reactor has a combined mole fraction of hydrogen and carbon dioxide greater than 0.5. 加热所述第一进料气体；Heating the first feed gas; 将包含氢气和二氧化碳的已加热的第一进料气体传递通过所述反向水煤气变换反应器内的所述反向水煤气变换催化剂，以通过将所述二氧化碳的至少一部分转化为一氧化碳来形成反向水煤气变换气体料流；A heated first feed gas containing hydrogen and carbon dioxide is passed through the reverse water-gas shift catalyst within the reverse water-gas shift reactor to form a reverse water-gas shift gas stream by converting at least a portion of the carbon dioxide into carbon monoxide. 将所述反向水煤气变换气体料流从所述反向水煤气变换反应器传递到包含蒸汽甲烷重整催化剂的热交换后重整器；The reverse water-gas shift gas stream is transferred from the reverse water-gas shift reactor to a heat exchange post-reformer containing a steam methane reforming catalyst. 将包含甲烷和蒸汽的第二进料气体供应至所述热交换后重整器，其中到所述热交换后重整器的所述第二进料气体具有大于0.5的甲烷和水的组合摩尔分数，A second feed gas containing methane and vapor is supplied to the post-heat exchange reformer, wherein the second feed gas to the post-heat exchange reformer has a combined mole fraction of methane and water greater than 0.5. 其中所述反向水煤气变换气体料流在所述热交换后重整器内加热所述第二进料气体，以在所述已加热的第二进料气体被传递通过所述蒸汽甲烷重整催化剂时驱动蒸汽甲烷重整反应，以产生包含一氧化碳和氢气的蒸汽甲烷重整气体料流，并且The reverse water-gas shift gas stream heats the second feed gas in the post-heat exchange reformer to drive a steam methane reforming reaction as the heated second feed gas is passed through the steam methane reforming catalyst, producing a steam methane reforming gas stream containing carbon monoxide and hydrogen. 其中包含一氧化碳和氢气的合成气产物料流离开所述热交换后重整器。The synthesis gas product stream, which contains carbon monoxide and hydrogen, exits the heat exchange-fed reformer. 2.根据权利要求1所述的方法，2. The method according to claim 1, 其中到所述反向水煤气变换反应器的所述第一进料气体具有大于0.6、0.7、0.8、0.9或0.95的氢气和二氧化碳的组合摩尔分数。The first feed gas to the reverse water-gas shift reactor has a combined molar fraction of hydrogen and carbon dioxide greater than 0.6, 0.7, 0.8, 0.9, or 0.95. 3.根据权利要求1或2所述的方法，3. The method according to claim 1 or 2, 其中到所述热交换后重整器的所述第二进料气体具有大于0.6、0.7或0.8的甲烷和水的组合摩尔分数。The second feed gas to the reformer after heat exchange has a combined molar fraction of methane and water greater than 0.6, 0.7, or 0.8. 4.根据任一前述权利要求所述的方法，4. The method according to any of the preceding claims, 其中所述第二进料气体具有高于所述第二进料气体内的二氧化碳的摩尔分数、氢气的摩尔分数或二氧化碳和氢气的组合摩尔分数中的一者或多者的甲烷的摩尔分数。The second feed gas has a higher molar fraction of methane than one or more of the following: the molar fraction of carbon dioxide, the molar fraction of hydrogen, or the combined molar fraction of carbon dioxide and hydrogen. 5.根据任一前述权利要求所述的方法，5. The method according to any of the preceding claims, 其中所述反向水煤气变换气体料流在所述热交换后重整器内与所述蒸汽甲烷重整气体料流混合，使得离开所述热交换后重整器的所述合成气产物料流包含所述反向水煤气变换气体料流和所述蒸汽甲烷重整气体料流的混合物。The reverse water-gas shift gas stream is mixed with the steam methane reforming gas stream in the post-heat exchange reformer, such that the syngas product stream leaving the post-heat exchange reformer contains a mixture of the reverse water-gas shift gas stream and the steam methane reforming gas stream. 6.根据权利要求1至4中任一项所述的方法，6. The method according to any one of claims 1 to 4, 其中所述反向水煤气变换气体料流在所述热交换后重整器内保持与所述蒸汽甲烷重整气体料流分离但与其热耦合，并且两个单独的合成气产物料流离开所述热交换后重整器，一个由所述反向水煤气变换气体料流形成，并且一个由所述蒸汽甲烷重整气体料流形成。The reverse water-gas shift gas stream is kept separate from but thermally coupled to the steam methane reforming gas stream within the post-heat exchange reformer, and two separate syngas product streams exit the post-heat exchange reformer, one formed by the reverse water-gas shift gas stream and the other formed by the steam methane reforming gas stream. 7.根据任一前述权利要求所述的方法，7. The method according to any of the preceding claims, 其中在所述第一进料气体进入所述反向水煤气变换反应器之前加热所述第一进料气体并且/或者在所述反向水煤气变换反应器内加热所述第一进料气体。The first feed gas is heated before entering the reverse water-gas shift reactor and/or heated inside the reverse water-gas shift reactor. 8.根据权利要求7所述的方法，8. The method according to claim 7, 其中所述第一进料气体通过以下项中的一者或多者加热：The first feed gas is heated by one or more of the following: 涡轮机械加热器，所述涡轮机械加热器在进入所述反向水煤气变换反应器之前直接加热所述第一进料气体；A turbomachinery heater that directly heats the first feed gas before it enters the reverse water-gas shift reactor; 加热热传递流体的涡轮机械加热器，所述热传递流体然后在进入所述反向水煤气变换反应器之前或在所述反向水煤气变换反应器内加热所述第一进料气体；A turbomachinery heater that heats a heat transfer fluid, which then heats the first feed gas before entering the reverse water-gas shift reactor or within the reverse water-gas shift reactor; 电加热系统，所述电加热系统在进入所述反向水煤气变换反应器之前或在所述反向水煤气变换反应器内运行；An electric heating system, which operates before entering the reverse water-gas shift reactor or within the reverse water-gas shift reactor; 一个或多个热交换器，所述一个或多个热交换器在进入所述反向水煤气变换反应器之前运行；One or more heat exchangers, which operate before entering the reverse water-gas shift reactor; 在所述反向水煤气变换反应器内燃烧氧气和氢气，所述反向水煤气变换反应器是自热重整器。Oxygen and hydrogen are burned in the reverse water-gas shift reactor, which is an autothermal reformer. 9.根据任一前述权利要求所述的方法，9. The method according to any of the preceding claims, 其中来自所述热交换后重整器的所述合成气产物料流的至少一部分通过自热重整器进料。At least a portion of the syngas product stream from the heat exchange reformer is fed through an autothermal reformer. 10.根据权利要求6和9所述的方法，10. The method according to claims 6 and 9, 其中所述热交换后重整器被构造成产生两个单独的合成气产物料流，一个由所述反向水煤气变换气体料流形成，并且一个由所述蒸汽甲烷重整气体料流形成，并且其中由所述蒸汽甲烷重整气体料流形成的所述合成气产物料流在与由所述反向水煤气变换气体料流形成的所述合成气产物料流混合之前通过所述自热重整器进料。The post-heat exchange reformer is configured to produce two separate syngas product streams, one formed by the reverse water-gas shift gas stream and the other by the steam-methane reforming gas stream, wherein the syngas product stream formed by the steam-methane reforming gas stream is fed through the autothermal reformer before being mixed with the syngas product stream formed by the reverse water-gas shift gas stream. 11.根据任一前述权利要求所述的方法，11. The method according to any of the preceding claims, 其中包含甲烷和蒸汽的所述第二进料气体至少部分地由以下项中的一者或多者形成：The second feed gas, which contains methane and vapor, is formed at least in part from one or more of the following: 从下游烃合成步骤中清除的、任选地反富集的气体；Gases that are optionally de-enriched and removed from downstream hydrocarbon synthesis steps; 石脑油或LPG料流，任选地进行了反富集，其从下游工艺分离以合成烃并对其进行提质；以及Naphtha or LPG feed streams, optionally reverse-enriched, are separated from downstream processes for the synthesis and upgrading of hydrocarbons; and 生物源进料源。Biological feed source. 12.一种产生烃的方法，所述方法包括：12. A method for producing hydrocarbons, the method comprising: 根据任一前述权利要求所述形成合成气；以及Forming syngas according to any of the preceding claims; and 将所述合成气传递穿过费托反应器以产生所述烃。The syngas is passed through a Fischer-Tropsch reactor to produce the hydrocarbons. 13.一种用于执行根据任一前述权利要求所述的方法的系统，所述系统包括：13. A system for performing the method according to any preceding claim, the system comprising: 第一进料气体供应单元，所述第一进料气体供应单元被构造成向反向水煤气变换反应器供应包含氢气和二氧化碳的第一进料气体，其中所述第一进料气体供应单元被构造成向所述反向水煤气变换反应器供应氢气和二氧化碳的组合摩尔分数大于0.5的所述第一进料气体；A first feed gas supply unit is configured to supply a first feed gas comprising hydrogen and carbon dioxide to a reverse water-gas shift reactor, wherein the first feed gas supply unit is configured to supply the reverse water-gas shift reactor with a combined mole fraction of hydrogen and carbon dioxide greater than 0.5. 加热单元，所述加热单元被构造成加热所述第一进料气体；A heating unit configured to heat the first feed gas; 反向水煤气变换反应器，所述反向水煤气变换反应器包含反向水煤气变换催化剂，所述反向水煤气变换反应器被构造成接收所述第一进料气体，将所述第一进料气体传递通过所述反向水煤气变换催化剂以形成反向水煤气变换气体料流，并且将所述反向水煤气变换气体料流从所述反向水煤气变换反应器传递到热交换后重整器；A reverse water-gas shift reactor, the reverse water-gas shift reactor comprising a reverse water-gas shift catalyst, the reverse water-gas shift reactor being configured to receive a first feed gas, pass the first feed gas through the reverse water-gas shift catalyst to form a reverse water-gas shift gas stream, and pass the reverse water-gas shift gas stream from the reverse water-gas shift reactor to a post-heat exchange reformer. 第二进料气体供应单元，所述第二进料气体供应单元被构造成将包含甲烷和蒸汽的第二进料气体供应至所述热交换后重整器，其中甲烷和水的组合摩尔分数大于0.5；和A second feed gas supply unit is configured to supply a second feed gas containing methane and vapor to the post-heat exchange reformer, wherein the combined molar fraction of methane and water is greater than 0.5; and 热交换后重整器，所述热交换后重整器包含蒸汽甲烷重整催化剂，所述热交换后重整器被构造成接收所述第二进料气体并将所述第二进料气体传递通过所述蒸汽甲烷重整催化剂，所述热交换后重整器还被构造成接收所述反向水煤气变换气体料流并提供从所述反向水煤气变换气体料流到所述第二进料气体的热交换以加热所述第二进料气体并在已加热的第二进料气体被传递通过所述蒸汽甲烷重整催化剂时驱动蒸汽甲烷重整反应以产生包含一氧化碳和氢气的蒸汽甲烷重整气体料流，所述热交换后重整器由此产生包含一氧化碳和氢气的合成气产物料流。A heat exchange post-reformer comprising a steam methane reforming catalyst, the heat exchange post-reformer being configured to receive a second feed gas and pass the second feed gas through the steam methane reforming catalyst, the heat exchange post-reformer being further configured to receive a reverse water-gas shift gas stream and provide heat exchange from the reverse water-gas shift gas stream to the second feed gas to heat the second feed gas and drive a steam methane reforming reaction to produce a steam methane reforming gas stream containing carbon monoxide and hydrogen when the heated second feed gas is passed through the steam methane reforming catalyst, the heat exchange post-reformer thereby producing a syngas product stream containing carbon monoxide and hydrogen. 14.根据权利要求13所述的系统，14. The system according to claim 13, 所述系统还包括包含费托催化剂的费托单元，所述费托单元被构造成接收所述合成气产物料流并将所述合成气产物料流传递通过所述费托催化剂以产生烃产物料流。The system also includes a Fischer-Tropsch unit containing a Fischer-Tropsch catalyst, the Fischer-Tropsch unit being configured to receive the syngas product stream and pass the syngas product stream through the Fischer-Tropsch catalyst to produce a hydrocarbon product stream.
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