How Blue Ammonia is Produced

Abstract

The present invention provides a method and system for producing blue ammonia that provides a higher percentage of carbon capture. The method and system of the present invention can be used in any ammonia plant.

Description

[Technical Field]

[0001] The present invention provides a method and plant for producing blue ammonia that provides a high percentage of carbon capture. The method and system of the present invention can be used in any ammonia plant. [Background technology]

[0002] Blue ammonia is a fossil-fuel-based product produced with minimal CO2 emissions into the atmosphere. It is considered a transitional product between conventional fossil-fuel-based ammonia and green ammonia, which is produced from green or renewable electricity and air. The CO2 resulting from blue ammonia production must be permanently stored or converted to other chemicals. The key steps for producing blue ammonia are essentially identical to those for producing conventional fossil-fuel-based ammonia; the difference is that more of the carbon derived from the carbonaceous fuel is captured, which opens up the possibility for further processing.

[0003] Importantly, blue ammonia does not release carbon dioxide when used as a fertilizer or burned. Currently available technology traps nearly all of the CO2 produced during the conversion process, making this fuel one of the first choices for carbon-free fuels for large-scale use. Blue ammonia is considered an environmentally friendly product that can be used until sufficient renewable or green electricity becomes available to produce green ammonia.

[0004] Document WO2018 / 149641 (Patent Document 1) discloses a method for the synthesis of ammonia from natural gas, which comprises converting a charge of desulfurized natural gas and steam together with oxygen-enriched air or oxygen into a synthesis gas (11) and treating the synthesis gas (11) by a shift reaction and decarbonization, wherein part of the CO2-depleted synthesis gas obtained after decarbonization is separated and used as a fuel fraction for one or more furnaces of the conversion section, and the remaining part of the gas is used to produce ammonia.

[0005] In DK PA 2022 00424 (Patent Document 2), off-gases from different process steps are utilized as fuel in a preheating system comprising one to several combustion heaters for preheating a hydrocarbon feedstock, with carbon capture from at least one heater, which allows the use of more carbon-rich fuels and thereby achieves a higher carbon capture rate (more than 98%) compared to the prior art.

[0006] It is known that over 60% of the CO2 can be captured from natural gas-based ammonia plants, as this is in the process gas (a by-product of hydrogen production). Many ammonia plants already use this CO2 stream to produce urea or sell it as food-grade CO2. The remaining CO2 emissions are in the much more dilute flue gas (a product of fuel combustion to preheat the process stream). For decades, it has been thought that most of this could be captured, but there has always been a persistent question: how much of that CO2 in the flue gas can be economically captured? [Prior art documents] [Patent documents]

[0007] [Patent Document 1] WO2018 / 149641 [Patent Document 2] DK PA202200424 Summary of the Invention

[0008] To achieve net-zero targets, CO2 capture rates should be as high as economically feasible and as close to 100% as technically possible. However, 100% capture rates remain very difficult for absorption-based systems, and residual emissions must be captured indirectly by a CDR. In the present invention, flue gas carbon capture using a CDR is an absorption-based, amine solvent-based technology. Economic feasibility further limits capture rates to the 90-99% range. In other words, it would be easier to capture the last 1% from air as opposed to attempting to capture it directly from treated flue gas.

[0009] The present invention provides an economical method for achieving high percent carbon capture, at least 98% by weight.

[0010] Summary of the Invention The present invention provides a method, system, and plant for producing ammonia with a high percentage of carbon capture, preferably greater than 98% by weight, compared to the prior art, where optimally, between about 90% and 93% by weight of carbon capture is achieved. Ammonia plants within the scope of the present invention may be retrofitted or new plants for the production of ammonia. Retrofitted plants are existing or conventional plants for the production of ammonia that have been modified, for example, to improve their operation, performance, economics, or carbon emissions. Furthermore, the fuel section may include a reforming waste heat section (WHS)—see Figures 2a) and 3—or one or more combustion heaters—see Figure 2b), where at least one of the combustion heaters or reforming WHSs is equipped with a CDR unit that captures 80% by weight (or 80% by volume) or more of CO2 from the resulting flue gas. This leads to an overall carbon capture efficiency of at least 98% by weight.

[0011] Utility prices vary depending on the plant / site location. For a given specific utility price, it will change which blue ammonia layout will be most optimal and attractive. The present invention provides a beneficial alternative compared to a similar layout without an HTER when natural gas prices rise and / or electricity prices fall (Table 1 and Figure 4).

[0012] The method of the present invention provides the following advantages: - Applicable to general plants and as retrofits; - Utilizing the CO2 capture step already available in the ammonia process to achieve complete CO2 capture; - Allows for CO2 capture of more than 98% by weight; - Lower operating costs, especially when natural gas prices rise and / or electricity prices fall (Table 1, Figure 4); - Reducing the amount of flue gas and therefore reducing NOx formation and thereby reducing NOx emissions into the atmosphere.

[0013] The above advantages are provided by a series of features, including: - the reforming step includes heat exchange reforming by connecting the HTER to the reforming section; and - From a secondary reformer (two-stage reforming) or ATR (e.g., Syncor Ammonia 商標 The reformed or process gas collected from the reactor (at) is treated in a heat exchange reforming step, in which at least a portion of the transferred heat is used.

[0014] Description of the Invention Reducing CO2 emissions has become a challenge in the chemical industry. The production of ammonia using hydrocarbons as feedstocks inevitably results in CO2 formation, which typically results in at least two CO2-containing process streams: one nearly pure CO2 stream (1) removed from the syngas cleaning section and one or more flue gas streams (2). CO2 stream (1) can be utilized for further chemical processing or can be stored. The CO2 in the flue gas stream(s) (2) needs to be captured until it can find a similar use.

[0015] It is well known that CO2 in flue gas can be avoided by using carbon-free fuels. Generally, hydrocarbons, such as natural gas, and carbon-containing off-gases derived from the process are used as fuels. A post-combustion carbon capture or recovery unit, i.e., flue gas CDR, is applied to reduce the CO2 in the residual flue gas. One major advantage of the present invention is that the HTER can be connected to a two-stage reforming (Figures 2a and 3) or to an ATR (Figure 2b) to reduce the amount of flue gas, thereby reducing the CO2 content in the stream and reducing the cost of operating an ammonia plant.

[0016] definition Autothermal reforming (ATR), a combined steam reforming and partial oxidation process, is a promising technology for low-cost and reliable hydrogen production. Compared to steam reforming, it is easier to operate with smaller systems, better temperature control, lower energy requirements, easier startup, and less coking. In ATR, the reaction takes place in a single chamber, where methane is partially oxidized. This reaction is exothermic due to the oxidation. The main difference between autothermal reforming and steam methane reforming is that steam methane reforming does not use or require oxygen. However, the main drawback of autothermal reforming is the large investment required for an oxygen production plant, which is simply cost-effective only at high production capacities. While air can be used directly instead of oxygen, the presence of inert nitrogen causes a large gas volume, and therefore the system requires larger equipment.

[0017] Generally, autothermal reforming processes are operated under adiabatic conditions, and the product composition and reaction temperature depend on various operating parameters, such as the fuel, water, and air preheating temperatures, pressure, fuel composition, heat loss, steam-to-carbon ratio, and air-to-carbon ratio. Fuels suitable for autothermal reforming are highly flexible, including several gaseous hydrocarbons, such as methane, natural gas, and LPG, as well as liquid hydrocarbons, such as gasoline, diesel, alcohol, naphtha, residual oil, ethylene glycol, and glycerol. Appropriate operating conditions (e.g., catalyst, temperature, fuel / oxidant ratio, and treatment process) strongly depend on the fuel quality, i.e., the carbon number and purity of each fuel. The use of heavy hydrocarbon fuels containing some impurities can easily suppress reforming performance due to coke formation and catalyst poisoning. Although less carbon deposition is typically observed in autothermal reforming compared to steam reforming, significant amounts of carbon deposition have still been widely reported in the autothermal reforming of propane, butane, and gasoline, even under steam-rich conditions. Even small amounts of sulfur can significantly reduce the useful life of a catalyst.

[0018] In the present invention, the process gas or reformate gas produced in the ATR can be used as a heat source for partial reforming in a heat exchange reformer (HTER).

[0019] Blue ammonia is ammonia produced from the use of fossil fuels in which at least 90% of the carbon in the fossil fuels is captured or recovered and used in other products and processes, or stored.

[0020] Carbon dioxide removal (CDR) processes encompass both CO capture (or capture or removal) from synthesis gas (pre-combustion carbon capture) and CO capture (or capture or removal) from flue gas (post-combustion carbon capture). In the present invention, CDR refers to CO capture (or capture or removal) from flue gas (post-combustion carbon capture (or capture or removal)). CO capture, capture, or removal are intended to mean the same thing in this application.

[0021] Flash gas or process condensate refers to the intermediate gas stream obtained during the CO2 capture step.

[0022] Flue gas in this invention means the mixture of combustion products including water vapor, carbon dioxide, particulates, heavy metals and acid gases obtained from the combustion of fuel in section (g). Some or all of the flue gas from the reformer waste heat section (WHS) or combustion heater(s) is further processed in the CDR.

[0023] The fuel section includes a fuel system for supplying fuel to the tubular reformer and / or combustion heater and / or auxiliary boiler and / or combustion side of the gas turbine. Preferably, the fuel section includes at least one waste heat section (WHS) or includes one or more combustion heaters. These systems include one or more burners in which an incoming fuel stream is combusted with air at variable temperatures and pressures.

[0024] The hydrocarbon feedstock is any hydrocarbon suitable for ammonia production, preferably natural gas or methane.

[0025] Make-up gas is a stream obtained from the purification unit prior to entering the ammonia loop or ammonia synthesis section (f).

[0026] Methanation means that the purification step is the conversion of carbon monoxide and carbon dioxide (CO2) to methane (CH4) by hydrogenation. The methanation reaction (Equation 1 and Equation 2) is exothermic, and at normal operating temperatures (250-350°C), the equilibrium lies far to the right.

[0027] [ka] Using this route, carbon monoxide and carbon dioxide impurities can be reduced to less than a few ppm. The advantages of methanation, i.e., its simplicity and low cost, far outweigh its disadvantages, i.e., hydrogen consumption and the production of additional inerts in the make-up gas to the synthesis loop. Methanation can be carried out in a methanator or methanation section.

[0028] Nitrogen scrubbing or liquid nitrogen scrubbing can be used as a final purification step, delivering gas free of all impurities, including inert gases, to the ammonia synthesis loop. It also provides a means of adding, in whole or in part, the nitrogen required for ammonia synthesis. It is primarily used in fertilizer plants to purify and produce ammonia synthesis gas. It is usually the last purification step upstream of ammonia synthesis. The liquid nitrogen scrubbing removes residual impurities, such as CO, Ar, and CH4, from the crude hydrogen stream, establishing a stoichiometric ratio of H2 / N2 of approximately 3:1. Carbon monoxide is toxic to the ammonia synthesis catalyst and must be completely removed. Ar and CH4 are inert components that enrich in the ammonia synthesis loop. If not removed, syngas purging or purge gas separation costs would be required. Crude hydrogen (the hydrogen-rich process stream) and high-pressure nitrogen are fed to a liquid nitrogen scrubbing unit. Both streams are cooled by contact with the product gas. Crude hydrogen is fed to the bottom of the nitrogen scrubbing column, and some condensed nitrogen liquid is fed to the top. Trace components are removed and separated as fuel gas. High pressure nitrogen is added to the process stream to establish the desired H2 / N2 ratio. The nitrogen scrubbing unit (NWU) is the unit or section where liquid nitrogen scrubbing takes place.

[0029] Off-gas from one or more sections such as the CO2 capture section, hydrogen purification section or ammonia recovery section is used as fuel, preferably in the primary reformer (Figure 2a) or ATR (Figure 2b).

[0030] PSA stands for Pressure Swing Adsorption and allows for the energy-efficient recovery of specific compounds from gases under pressure.

[0031] If excess steam is available in the plant, a pre-reformer can be installed in the reformer section to reduce steam production, reducing the duty of the primary reformer and therefore gas consumption. The installation of a pre-reformer typically reduces the size of the primary reformer by up to 25%, while also reducing energy consumption. This technology can also be used to increase production capacity without additional energy costs. Installing a pre-reformer in an existing plant typically increases production by 10-20%. Other advantages of this technology include increased flexibility in terms of the feedstock going to the steam reformer and extended life of the steam reformer and shift catalyst, since substantially all of the sulfur in the hydrocarbon feed and process steam is absorbed by the pre-reforming catalyst.

[0032] The primary reformer is an energy absorption unit that requires an external heat source at elevated temperatures. It is where hydrogen is produced by the steam-hydrocarbon reforming reaction. The reforming reaction, which is endothermic in nature, consumes a large amount of energy. Approximately 80% of the fuel consumption of an ammonia plant is in the primary reformer burner. In the present invention, the primary reformer is preferably a tubular reformer, such as a steam methane reformer (SMR).

[0033] Steam reforming is a key process in the formation of syngas for ammonia and methanol production. The reforming section is typically the largest, most expensive, and most energy-intensive unit in these plants, and efficient and reliable operation is key to overall plant performance. The reforming section contains one or more reformers arranged in series or parallel. Optionally, the reforming section can include a pre-reformer upstream of the primary reformer.

[0034] In steam methane reforming applications, the reformer is a large unit with flue gas heat losses that must be minimized through a complex waste heat recovery section. Therefore, several alternative configurations can be developed using heat exchanger reformers (HTERs). These alternative approaches can be used to reduce the footprint and / or debottleneck existing facilities. In the present invention, the HTER, i.e., heat exchanger convection reformer, can be arranged in series or parallel with, for example, an autothermal reformer (ATR), a tubular reformer (SMR), or a two-stage reforming configuration (e.g., an SMR followed by a secondary reformer) using heat from the ATR or secondary reformer effluent. This is theoretically suitable for all synthesis gas production, particularly hydrogen and ammonia production. Retrofitting existing plants to larger capacities and for new plants is a cost-effective option, and this technology offers a lower footprint or even higher single-line capacity and reduced flue gas volume.

[0035] The secondary reformer produces excess energy and, within the context of the present invention, may be an ATR, HTER, or other. Generally, the secondary reformer in an ammonia plant plays an important role in further converting methane from the primary reformer and supplying nitrogen by controlling the air flow rate, and the optimal molar ratio of synthesis gas (CO+H2) to nitrogen may be about 3.0.

[0036] The shift step is the reaction of the synthesis gas with steam in a reaction zone to convert carbon monoxide to a crude gas mixture containing carbon dioxide and hydrogen. At the outlet of a steam reformer, particularly an HTER, the syngas contains H, CO, CO, CH, and water in chemical equilibrium at high temperatures in the approximate range of 700-1040°C, depending on the process pressure and the mixture of feedstock with process streams or water. Through the CO shift conversion, most of the CO content in the synthesis / process gas is used for additional hydrogen production, which follows the chemical reaction: CO+H2O<=>H2+CO2

[0037] The process is exothermic and limited by chemical equilibrium. Three different versions of CO shift conversion exist: (i) high-temperature (HT) CO shift conversion at about 320-450 °C, down to about 3.5% CO on a dry basis at the reactor outlet; (ii) intermediate-temperature (MT) CO shift conversion at about 190-330 °C, down to about 0.8% CO on a dry basis at the reactor outlet; and (iii) low-temperature (LT) CO shift conversion at about 180-230 °C, down to about 0.3% CO on a dry basis at the reactor outlet.

[0038] The application of low-temperature CO shift conversion is usually installed downstream of the HT shift with the CO content in the feed gas already reduced. In the present invention, the shift section (c) can include a high-temperature shift, a medium-temperature shift, and / or a low-temperature shift, and preferably the shift conversion is carried out in two stages, with a high-temperature shift (HTS) catalyst being used as the first stage, typically converting more than 80% of the CO, followed by the use of a low-temperature shift catalyst (LTS), which converts most of the remaining CO.

[0039] The process gas leaving the secondary reformer contains 12–15% (dry gas basis) CO (two-stage reforming layout). The process gas leaving the ATR contains 25–30% (dry gas basis) CO (SynCOR layout). In the shift section, most of the CO is converted to CO2. The performance of the shift conversion is very important for the overall efficiency of the ammonia plant because unconverted CO consumes hydrogen (3*H2:1*CO) in the methanator to form CH4 (two-stage reforming layout), reducing feedstock efficiency and increasing the inerts content in the synthesis loop. In the SynCOR layout, unconverted CO ultimately enters the off-gas from the hydrogen purification step, and its impact on hydrogen production is less significant (1*H2:1*CO). Traditionally, the shift reaction is carried out in two steps with a heat removal step in between. First, in the two-stage reforming layout, the process gas passes through a bed of iron oxide / chromium oxide catalyst at approximately 350-380°C (high-temperature shift conversion). In the SynCOR layout, the process gas passes through a catalyst bed of zinc-aluminum spinel and zinc oxide, optionally combined with an alkali metal selected from the group consisting of Na, K, Rb, Cs, and mixtures thereof, at approximately 320-450°C (high-temperature shift conversion step). After the HTS step, in both layouts, the process gas continues through a copper oxide / zinc oxide catalyst at approximately 200-230°C (low-temperature shift conversion). The result is a process gas with a residual CO content of 0.2-0.5% (dry gas basis). Newer developments can utilize isothermal shift single-stage conversion. The process gas exiting the low-temperature shift converter is cooled, and after the majority of the vapors are condensed and removed, it passes through a CO2 capture section. The heat released during cooling and condensation can be used for other purposes, for example, to regenerate the CO2 scrubbing unit.

[0040] Steam methane reforming (SMR), or tubular reforming, refers to the process in which methane from natural gas is heated with steam, usually with a catalyst, to produce a mixture of carbon monoxide and hydrogen, which is used in organic synthesis and as a fuel. In the energy industry, SMR is one of the most widely used processes for the production of hydrogen.

[0041] Two-stage reforming is characterized by a combination of tubular reforming (primary reforming) and oxy-fuel autothermal reforming (ATR) (secondary reforming). Two-stage reforming produces a process gas or reformate gas. In the present invention, the process gas can be further reformed in a heat exchange reformer (HTER) resulting in a three-stage reforming layout, or, if a pre-reformer is used, a four-stage reforming layout.

[0042] Preferred Embodiments 1.Follow these steps: i) preheating the hydrocarbon feed; ii) removing sulfur and other contaminants from the preheated hydrocarbon feed; iii) reforming the preheated hydrocarbon feedstock to obtain a synthesis gas containing CO, CO2, H2, H2O and CH4; iv) passing the synthesis gas through a shift reaction step to reduce the CO content; v) sending the CO2-depleted synthesis gas to a CO2 capture step, wherein said gas is split into at least a CO2-rich stream and a hydrogen-rich stream, and optionally a flash gas stream; vi) passing the hydrogen-rich stream through a purification step; vii) passing a portion of the synthesis gas stream obtained in the preceding step through an ammonia synthesis section to convert said portion to ammonia, and optionally sending another portion of said synthesis gas stream to a fuel section; 1. A method for producing ammonia, comprising: The reforming step includes heat exchange reforming (HTER); and - at least a portion of the heat in the synthesis gas from the reforming step (secondary reformer or autothermal reformer) is used in the heat exchange reforming step; - at least 80% by weight of the CO2 is captured from the flue gas, and - at least 98% by weight of total CO2 is captured; The method.

[0043] At least up to 98% by weight of total CO2 can be captured using flue gas CDR (applicable to all layouts).

[0044] At least 98% of the CO2 can be captured for all layouts, but for the two-stage reforming layouts with or without HTER-p or -s, more CO2 can be captured from the flue gas in the CDR compared to the SynCOR layout.

[0045] 2. The method according to embodiment 1, wherein one or more carbon-containing off-gas streams are sent to the fuel section (g).

[0046] 2.1 The process according to embodiment 1, wherein one or more carbon-containing off-gas streams are sent to the reforming section (b). This can reduce the size of the flue gas carbon capture unit required.

[0047] 3. The method according to embodiment 1 or 2, wherein CO2 in the flue gas coming from the reforming waste heat section and / or the combustion heater(s) is captured by the CDR unit(s).

[0048] 4. The process according to embodiment 1 or 3, wherein at least a portion of the hydrocarbon feedstock is subjected to two-stage reforming and another portion is subjected to heat exchange reforming.

[0049] 5. The process according to any one of embodiments 1 to 4, wherein at least a portion of the hydrocarbon feedstock undergoes primary reforming, an air-blown secondary reforming step, and heat exchange reforming.

[0050] 5.1. The process according to the previous embodiment, wherein the amount of air to the air-blown secondary reformer is adjusted to obtain a molar ratio of N2 to H2 of between 1:2.5 and 1:3.5 in the stream from the methanation reactor.

[0051] 6. The method according to any one of embodiments 1 to 5, wherein the secondary reforming step is followed by heat exchange reforming, and at least a portion of the heat generated in the secondary reformer is used in the HTER.

[0052] 6.1 The process according to any one of embodiments 1 to 5, wherein the heat exchange reforming step is followed by secondary reforming, and at least a portion of the heat generated in the secondary reformer is used in the HTER.

[0053] 6.2 The process according to any one of embodiments 1 to 5, wherein at least a portion of the hydrocarbon feedstock is directed to an HTER.

[0054] 6.3 The process according to any one of the preceding embodiments, wherein the preheated and desulfurized hydrocarbon outlet stream is split into a stream that is directed to a heat exchange reformer and another stream that is directed to a pre-reformer (b0) or a primary reformer or an autothermal reformer.

[0055] 7. The method according to any one of embodiments 1-6, wherein the purification step is methanation, in which CO and CO2 are converted to CH4 and HO along with hydrogen to obtain a synthesis gas stream comprising nitrogen and hydrogen.

[0056] 7.1 The method according to the previous embodiment, wherein a purge gas stream comprising CH4 from the ammonia synthesis is added to the resulting synthesis gas.

[0057] 8. The process according to any one of embodiments 1-3, wherein at least a portion of the hydrocarbon feedstock undergoes autothermal reforming and heat exchange reforming.

[0058] 9. The method according to any one of embodiments 1-3 and 8, wherein the autothermal reforming step is followed by heat exchange reforming, and at least a portion of the heat generated in the ATR is used in the HTER.

[0059] 9.1 The process according to embodiment 8, wherein the heat exchange reforming step is followed by autothermal reforming, and at least a portion of the heat generated in the ATR is used in the HTER.

[0060] 10. The method according to any one of embodiments 1, 3, and 8, wherein the purification step is a hydrogen purification or nitrogen scrubbing step, in which HO, CO, CO, CH are removed in the off-gas stream to obtain a purified hydrogen stream, and nitrogen is added to obtain an ammonia synthesis gas stream comprising nitrogen and hydrogen.

[0061] 10.1 The process according to the previous embodiment, wherein the purification step is a PSA step in which a hydrogen stream comprising more than 99.5% by volume of hydrogen is obtained, to which nitrogen is added to obtain a synthesis gas stream and an off-gas stream comprising nitrogen and hydrogen.

[0062] 11. The method according to any one of the preceding embodiments, comprising a step of pre-reforming the hydrocarbon feedstock.

[0063] 12. The method according to any one of the preceding embodiments, wherein a synthesis gas stream originates from the purification step and is used as fuel.

[0064] 13. The method according to any one of the preceding embodiments, wherein a make-up gas stream comprising N2 and H2 originates downstream of the purification step and is used as fuel.

[0065] 13.1 The method according to the previous embodiment, wherein the makeup gas stream obtained from the purification step comprises N2 and H2 in a ratio of between 1:2.9 and 3.1.

[0066] 14. The process according to any one of the preceding embodiments, wherein at least a portion of the hydrocarbon feedstock, at least a portion of the flash gas from a CO2 capture step, at least a portion of the off-gas or synthesis gas from a purification step, at least a portion of the make-up gas originating downstream of the purification step, and at least a portion of the off-gas from an ammonia recovery section are premixed or fed separately to the combustion section (g) and used as fuel.

[0067] 15. The following: I. Preheating section (not shown) II. Desulfurization Section (a) III. Modification section (b); IV. Shift section (c); V.CO2 capture section (d); VI. Purification section (e); VII. Ammonia synthesis section (f) (not shown); and VIII. Fuel section (g) (not shown); 15. A plant for producing ammonia according to the method of any one of claims 1 to 14, comprising: The plant, wherein the reforming section (b) is connected to a heat exchange reformer (HTER).

[0068] 16. A plant according to embodiment 15, wherein the fuel section includes a reforming waste heat section or one or more combustion heaters equipped with a CDR unit for capturing CO2 from the flue gas.

[0069] 17. A plant according to embodiment 15 or 16, wherein the reforming section is arranged downstream of a pre-reformer (b0), such as an adiabatic pre-reformer.

[0070] 18. The plant of any one of embodiments 15-17, wherein the purification section (e) comprises a nitrogen wash unit (NWU) or a pressure swing adsorption (PSA) unit or a methanator.

[0071] 19. The plant of any one of embodiments 15-18, wherein the reforming section includes a primary reformer and a secondary reformer associated with an HTER.

[0072] 20. A plant according to any one of embodiments 15 to 19, wherein the HTER is positioned in parallel with the reforming section and downstream of the secondary reformer.

[0073] 20.1 A plant according to any one of embodiments 15 to 19, wherein the HTER is disposed in series with the reforming section and upstream of the secondary reformer.

[0074] 21. A plant according to any one of embodiments 15 to 20, wherein the reforming section includes an air-blown secondary reformer disposed downstream of the primary reformer.

[0075] 21.1 The plant according to any one of embodiments 15 to 21, wherein the purification unit is a methanator.

[0076] 21.2 The plant according to any one of embodiments 15 to 22, wherein the fuel section (g) comprises one or more waste heated section(s).

[0077] 21.3 A plant according to any one of embodiments 15 to 23, wherein the reforming section is a two-stage reforming section associated with an HTER, the purification unit is a methanator unit, and the fuel section includes one or more waste heat sections equipped with one or more CDR units.

[0078] 21.4 A plant according to the previous embodiment, wherein the two-stage reforming section comprises a primary reformer (b1), preferably a tubular steam reformer, e.g., SMR, and a secondary reformer (b2), e.g., ATR or other.

[0079] 22. The plant of any one of embodiments 15-18, wherein the reforming section comprises an ATR associated with an HTER.

[0080] 22.1 A plant according to any one of embodiments 15 to 18 and 22, wherein the HTER is positioned downstream of the ATR, in parallel with the reforming section.

[0081] 22.2 A plant according to any one of embodiments 15-18 and 22-23, wherein the HTER is disposed in series with the reforming section and upstream of the ATR.

[0082] 22.3 A plant according to any one of embodiments 15 to 18 and 22 to 24, wherein the refining unit is a NWU or a PSA.

[0083] 22.4 The plant according to any one of embodiments 15-18 and 22-25, wherein the fuel section includes one or more combustion heaters.

[0084] 22.5 A plant according to any one of embodiments 15-18 and 22-26, wherein the purification unit is preferably an NWU or a PSA, and the fuel section includes one or more combustion heaters equipped with one or more CDR units, when the ATR is used as a secondary reformer in a two-stage reforming section or as a single-stage reformer. [Brief explanation of the drawings]

[0085] Figure 1a) shows an example of a schematic for producing ammonia according to DK PA 2022 00424 using a steam reformer followed by an autothermal reformer in syngas production: a) Desulfurization b) Pre-reforming b) Modified (SMR) b) Modification (ATR) c) Shift section d) CO2 Capture Section e) Refining section (e.g. methanation unit) f) Ammonia synthesis section g) A fuel section (e.g., one or more waste heat sections) including a flue gas CDR unit (not shown) i) An ammonia recovery section, optionally including a hydrogen recovery unit (HRU).

[0086] Figure 1b) shows an alternative to Figure 1a), but including one or more fired heaters in the fuel section including a NWU or PSA as the purification unit and a CDR unit (not shown) for capturing CO2 from some or all of the flue gas.

[0087] FIG. 2 shows two preferred embodiments of the present invention, having a) two-stage reforming or b) ATR connected with an HTER in reforming section (b) (three-stage reforming).

[0088] FIG. 3 shows a third preferred embodiment in which the three-stage reforming utilizes enriched air.

[0089] All three embodiments shown in Figures 2 and 3 include the hydrocarbon (HC) feed (not shown), ammonia synthesis (f) section and fuel section (g) as shown in Figures 1a) and 1b), and their interactions (also not shown).

[0090] Figure 4 shows when a three-stage reforming layout including HTER becomes attractive in terms of NG and electricity prices, for example, if the values ​​in Table 1 below are applied as a base and then either the natural gas or electricity prices fluctuate:

[0091] [Table 1]

[0092] Example 1 Table 2 shows the benefits of the proposed layout in terms of carbon capture or recovery (%).

[0093] Traditional ammonia production involves utilizing off-gas from the ammonia recovery and syngas preparation steps to supplement natural gas as the primary fuel for the fired heater / process furnace. This results in carbon emissions from the flue gas stack of 65-71% for a two-stage reforming layout with or without an HTER. Using the layout disclosed in document DK PA202200424, including a CDR for flue gas carbon capture, this results in a significant reduction in carbon emissions, with capture or recovery of up to over 98% being obtained.

[0094] Advantageously, the present invention provides the layout in the right-most column in Table 2, which shows that a smaller flue gas carbon capture unit, i.e., CCU / CDR, is required in the layout including the HTER (FIG. 2a) compared to the conventional two-stage layout including the CDR (FIG. 2a).

[0095] [Table 2]

Claims

1. Steps below: i) preheating the hydrocarbon feed; ii) removing sulfur and other contaminants from the preheated hydrocarbon feed; iii) Reforming the preheated hydrocarbon feedstock to produce CO, CO ２ , H ２ , H ２ O and CH ４ obtaining a synthesis gas containing iv) passing the synthesis gas through a shift reaction step to reduce the CO content; v) CO2-depleted synthesis gas ２ a step of sending the gas to a capture step, the gas comprising at least ２ splitting into a rich stream and a hydrogen-rich stream, and optionally a flash gas stream; vi) passing the hydrogen-rich stream through a purification step; vii) passing a portion of the synthesis gas stream obtained in the preceding step through an ammonia synthesis section to convert said portion to ammonia, and optionally sending another portion of said synthesis gas stream to a fuel section; 1. A method for producing ammonia, comprising: The reforming step comprises heat exchange reforming (HTER); and at least a portion of the heat in the synthesis gas from the reforming step (secondary reformer or autothermal reformer) is used in the heat exchange reforming step; -CO ２ is captured from the flue gas; and -CO ２ At least 98% by weight of the total is captured; The method.

2. The method of claim 1 , wherein one or more carbon-containing off-gas streams are sent to the fuel section (g).

3. CO in the flue gas coming from the reforming waste heat section and / or combustion heater(s) ２ The method of claim 1 or 2, wherein is captured by the CDR unit(s).

4. 4. The process of claim 1 or 3, wherein at least a portion of the hydrocarbon feedstock is subjected to two-stage reforming and another portion is subjected to heat exchange reforming.

5. The method according to any one of claims 1 to 4, wherein at least a portion of said hydrocarbon feedstock is subjected to primary reforming, an air-blown secondary reforming step and heat exchange reforming.

6. The method according to any one of claims 1 to 5, wherein the secondary reforming step is followed by heat exchange reforming, and at least a portion of the heat generated in the secondary reformer is used in the HTER.

7. The purification step is methanation, in which CO and CO ２ together with hydrogen ４ and H ２ 7. The process of claim 1, wherein O is converted to a synthesis gas stream comprising nitrogen and hydrogen.

8. The method of any one of claims 1 to 3, wherein at least a portion of the hydrocarbon feedstock is subjected to autothermal reforming and heat exchange reforming.

9. 9. The method according to any one of claims 1 to 3 and 8, wherein the autothermal reforming step is followed by heat exchange reforming, and at least a portion of the heat generated in the ATR is used in the HTER.

10. The purification step is a hydrogen purification or nitrogen scrubbing step, wherein H ２ O, CO, CO ２ , C.H. ４ 10. The method of any one of claims 1, 3 and 8, wherein is removed in the off-gas stream to obtain a purified hydrogen stream, and nitrogen is added to obtain an ammonia synthesis gas stream comprising nitrogen and hydrogen.

11. A method according to any one of claims 1 to 10, comprising a step of pre-reforming the hydrocarbon feedstock.

12. The method of any one of claims 1 to 11, wherein a synthesis gas stream originates from said purification step and is used as fuel.

13. N ２ and H ２ The method of any one of claims 1 to 12, wherein a make-up gas stream comprising:

14. at least a portion of the hydrocarbon feedstock, CO ２ 14. The method according to any one of claims 1 to 13, wherein at least a portion of the flash gas from the capture step, at least a portion of the off-gas or synthesis gas from the purification step, at least a portion of the make-up gas originating downstream of the purification step, and at least a portion of the off-gas from the ammonia recovery section are premixed or separately supplied to the combustion section (g) and used as fuel.

15. below: IX. Preheat Section (not shown) X. Desulfurization Section (a) XI. Modification section (b); XII. Shift section (c); XIII.CO ２ capture section (d); XIV. Purification section (e); XV. Ammonia synthesis section (f) (not shown); and XVI. Fuel section (g) (not shown); A plant for producing ammonia according to the method of claims 1 to 14, comprising: The plant, wherein the reforming section (b) is connected to a heat exchange reformer (HTER).

16. The fuel section extracts CO from the flue gas. ２ 16. The plant of claim 15, comprising a reforming waste heat section or one or more combustion heaters with a CDR unit for capturing

17. 17. A plant according to claim 15 or 16, wherein the reforming section is arranged downstream of a pre-reformer (b0), such as an adiabatic pre-reformer.

18. The plant of any one of claims 15 to 17, wherein the purification section (e) comprises a nitrogen wash unit (NWU) or a pressure swing adsorption (PSA) unit or a methanator.

19. A plant according to any one of claims 15 to 18, wherein the reforming section comprises a primary reformer and a secondary reformer associated with an HTER.

20. A plant according to any one of claims 15 to 19, wherein the HTER is arranged in parallel with the reforming section and downstream of the secondary reformer.

21. A plant according to any one of claims 15 to 20, wherein the reforming section comprises an air-blown secondary reformer located downstream of the primary reformer.

22. A plant according to any one of claims 15 to 18, wherein the reforming section comprises an ATR associated with an HTER.

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