METHOD FOR PRODUCING A SYNTHETIC GAS PRODUCT FLOW WITH REDUCED CARBON MONOXIDE EMISSION

Description

Field of invention

[0001] The invention relates to a method and a plant for producing a synthesis gas product stream by steam reforming of hydrocarbons, wherein the emission of carbon monoxide, which is released to the environment together with a carbon dioxide rich gas stream, is reduced. State of the art

[0002] Hydrocarbons can be catalytically converted with steam to synthesis gas, i.e., mixtures of hydrogen (H₂) and carbon monoxide (CO). As explained in Ullmann's Encyclopedia of Industrial Chemistry, Sixth Edition, 1998 Electronic Release, entry "Gas Production," this so-called steam reforming is the most widely used method for the production of synthesis gas, which can subsequently be converted into other important basic chemicals such as methanol or ammonia. Although various hydrocarbons, such as naphtha, liquefied petroleum gas (LPG), or refinery gases, can be converted, the steam reforming of methane-containing natural gas is dominant.

[0003] After preheating by heat exchangers or fired heaters to a temperature above approximately 500 °C, for example up to 650 °C, the hydrocarbon vapor mixture, after final heating to approximately 800 to 950 °C, enters the reformer tubes of the steam reformer, which are heated by a multitude of burners. There, it is converted to carbon monoxide and hydrogen at the reforming catalyst. Nickel-based reforming catalysts are commonly used. While higher hydrocarbons are completely converted to carbon monoxide and hydrogen, methane typically undergoes only partial conversion. The composition of the product gas is determined by the reaction equilibrium; therefore, in addition to carbon monoxide and hydrogen, the product gas also contains carbon dioxide, unreacted methane, and water vapor.For energy optimization or when using feedstocks with higher hydrocarbon content, a so-called prereformer can be used after the preheater to pre-split the feedstock. The pre-split feedstock is then heated in a further heater to the desired reformer tube inlet temperature.

[0004] After leaving the reformer furnace, the hot raw synthesis gas is partially cooled in one or more heat exchangers via indirect heat exchange with process media to be heated. The partially cooled raw synthesis gas then undergoes further conditioning steps, which depend on the type of desired product or the downstream process. If the synthesis gas production is primarily aimed at generating pure hydrogen, the hydrogen content in the produced synthesis gas is increased by applying CO conversion, also known as the water-gas shift (WGS) or CO shift reaction.

[0005] Further processing of the raw synthesis gas often includes a method for separating the carbon dioxide, for example, by physical or chemical absorption or gas scrubbing. Such methods are also known as carbon capture (CC) processes. A well-known and frequently used method for carbon dioxide removal is the Rectisol process, which involves scrubbing the raw synthesis gas with cryogenic methanol as an absorbent and is also described in principle in the aforementioned literature. Other scrubbing processes utilize different scrubbing or absorbing agents, for example, N-methylpyrrolidone (NMP), secondary amines, e.g., diethanolamine, tertiary amines, e.g., methyldiethanolamine (MDEA), and polyethylene glycol dialkyl ethers, e.g., polyethylene glycol dimethyl ether. The specific process conditions to be applied here, the selection of which is familiar to those skilled in the art, are referred to below as carbon dioxide separation conditions.

[0006] In steam reforming processes that focus primarily or exclusively on the production of pure hydrogen or the synthesis gas products carbon monoxide and hydrogen, the separated carbon dioxide is often released into the atmosphere. During the regeneration of the scrubbing or absorbing agent, the separated carbon dioxide is obtained as a rich gas stream. The problem is that the separated and regenerated carbon dioxide still contains a certain proportion of carbon monoxide (CO). The carbon monoxide is co-absorbed in the solvent during the absorption step and released into the carbon dioxide rich gas stream during the regeneration step. When the carbon dioxide rich gas stream is released into the atmosphere, the permissible emission limit for CO is frequently exceeded. For example, according to Directive 2010 / 75 / EU of the European Parliament and of the Council of 24 September 2010, the limit is...November 2010, the emission limit for CO in industrial exhaust gases: . a) 50 mg / N m 3< as a daily average; b) 100 mg / N m 3< as a half-hour average; c) 150 mg / N m 3< as a ten-minute average.

[0007] One possible solution is therefore to include an additional flash stage between the absorption and regeneration stages. In this process, a large portion of the CO is separated before the actual regeneration stage by simple expansion and can, for example, be added to the fuel gas for the reformer burners. This allows the CO emission limit to be met. However, the significant additional investment costs for installing the flash stage are a disadvantage.

[0008] WO 2022 / 155425 A1 discloses a process and a plant for the production of synthesis gas by steam reforming. Natural gas and steam are reacted in reformer tubes containing a catalyst. The resulting synthesis gas is cooled and then treated with an amine in an absorber comprising an absorption column and a stripper column, thereby separating CO2. The reformer is heated by means of burners. The resulting flue gas is cooled against other process streams and catalytically treated with an SCR catalyst for NOx reduction. Description of the invention

[0009] The object of the present invention is therefore to provide a method and a plant for producing a synthesis gas product stream by steam reforming of hydrocarbons, in which the emission of carbon monoxide, which is released to the environment together with a carbon dioxide rich gas stream, is reduced.

[0010] This problem is solved in a first aspect by a method with the features of claim 1 and in a further aspect by a system with the features of claim 9. Further embodiments of the invention are described in the dependent claims of the respective category.

[0011] The steam reforming conditions or CO conversion conditions are known to those skilled in the art from the prior art, for example, from the documents discussed at the outset. These are the physicochemical conditions under which a measurable, preferably a technically relevant, conversion of hydrocarbons to synthesis gas products (steam reforming) or of carbon monoxide and steam to carbon dioxide and hydrogen is achieved according to the conversion equation given above. Necessary adjustments to these conditions to the respective operating requirements, for example, with regard to the reactant flow rates, pressures, reaction temperatures, in particular the steam reforming inlet temperature, and the type and quantity of catalysts used, will be made by those skilled in the art based on routine experiments. Any disclosed, specific reaction conditions may serve as a guide, but they are not to be understood as limiting with regard to the scope of the invention.

[0012] For the purposes of this disclosure, a physical or chemical carbon dioxide separation process is understood to be a process that enables a fluid mixture, for example, a gas mixture, to be separated into its components or unwanted components to be removed from this mixture by applying suitable physicochemical conditions, such as phase transitions like condensation or by using a suitable sorbent. If a sorption process is used, it can be based on adsorption, i.e., the binding of the substance(s) to be separated to a surface or interface of the solid adsorbent, or on absorption, i.e., the uptake of the substance(s) to be separated into the volume of the liquid or solid absorber. The separated substance(s) bound by sorption are referred to as the adsorbate or absorbate, respectively.The binding forces involved can be physical or chemical in nature. Accordingly, physical sorption is usually characterized by weaker, less specific binding forces, such as van der Waals forces, whereas chemical sorption involves stronger, more specific binding forces, resulting in chemical modification of the adsorbate or absorbate and / or the adsorbent or absorbent.

[0013] In this disclosure, the terms absorbent and detergent (in the case of liquid absorbents) are used as synonyms for the term absorber.

[0014] A specific physical absorption process is gas scrubbing with cryogenic methanol, which is used as the absorbent or scrubbing agent. The methanol's temperature has been cooled below ambient temperature, preferably below 0 °C, and most preferably below -30 °C, by means of refrigeration processes. This process is known to those skilled in the art as the Rectisol process.

[0015] In contrast, the well-known and frequently used amine scrubs for carbon dioxide absorption are based on chemical absorption (chemisorption) and achieve high purities even at relatively low pressures in the absorption column. Their selectivity is also usually higher than that of physical absorption processes.

[0016] In amine scrubbing, slightly alkaline aqueous solutions of amines, often ethanolamine derivatives, are used in an absorption unit (absorption section), usually designed as a scrubbing column. Absorption takes place at a low temperature, e.g., 40 °C, and a slightly elevated pressure, e.g., 8 bara. Fresh or regenerated absorbent is added to the top of the column, and the gas stream to be separated is introduced at the bottom. Here, carbon dioxide is reversibly chemically absorbed. The carbon dioxide-depleted gas exits the column at the top, and the loaded scrubbing agent is discharged at the bottom and fed into a desorption section, which is also frequently designed as a separation column. In the desorption column (regeneration section), the reaction is reversed at a higher temperature and lower pressure, thus releasing the absorbed carbon dioxide as a gas.It can then be discharged at the top of the desorption column and either reused or disposed of. The absorbent regenerated in this way is returned to the absorption section.

[0017] Methyldiethanolamine (MDEA), a commonly used absorbent in amine scrubbing, is typically employed in aqueous solutions. Activators, such as piperazine, are frequently added to accelerate carbon dioxide absorption, as described, for example, in the article "The Activator Mechanism of Piperazine in Aqueous Methyldiethanolamine Solutions," J. Ying et al., Energy Procedia 114 (2017), pp. 2078–2087. These mixtures are then referred to as activated MDEA solutions (aMDEA).

[0018] A fluid connection between two areas of the device according to the invention is understood to mean any type of connection that allows a fluid, for example, a gas flow, to flow from one of the two areas to the other, irrespective of any intermediate areas or components. In particular, a direct fluid connection is understood to mean any type of connection that allows a fluid, for example, a gas flow, to flow directly from one of the two areas to the other, without any further areas or components being interposed, with the exception of the transport processes themselves and the means required for them, such as pipelines, valves, pumps, compressors, and storage tanks. An example would be a pipeline that leads directly from one of the two areas to the other.

[0019] A means is understood to be something that enables or assists in achieving an objective. In particular, means for carrying out a specific process step are understood to be all those physical objects that a person skilled in the art would consider in order to carry out that process step. For example, a person skilled in the art would consider means for introducing or discharging a flow of material to include all transport and conveying devices, such as pipelines, pumps, compressors, and valves, which, based on their expert knowledge, appear necessary or useful for carrying out this process step.

[0020] All pressure specifications are given in absolute pressure units, abbreviated bara or bar(a), or in gauge pressure units, abbreviated barg or bar(g), unless otherwise specified in the individual context.

[0021] For the purposes of this description, steam is to be understood as synonymous with water vapor, unless otherwise specified in individual cases.

[0022] The invention is based on the understanding that it is not necessary to subject the entire carbon dioxide-rich gas stream to a purification step in order to reliably remain below the specified emission limit for carbon monoxide from the reformer system. Instead, according to the invention, the carbon dioxide-rich gas stream is divided into a first and a second part. The first part of the carbon dioxide-rich gas stream is alternatively introduced into one or more of the following locations: into the reformer furnace via at least one burner and / or into the reformer furnace outside the burners and at a point in the reformer furnace where the local gas temperature is at least 1000 °C and / or into the flue gas duct and / or into the flue gas stack.

[0023] According to the invention, the second part of the carbon dioxide-rich gas stream containing carbon monoxide is introduced into the reformer tubes.

[0024] In this way, the carbon monoxide content in the first part of the carbon dioxide-rich gas stream is effectively reduced through oxidation or afterburning. The resulting exhaust gas stream is discharged from the process together with, or as part of, the flue gas stream and released into the environment. The carbon monoxide content in the second part of the carbon dioxide-rich gas stream is reduced by transferring some of the CO it contains into the synthesis gas product stream, thus making it a valuable resource. Preferred embodiments of the invention

[0025] A second aspect of the method according to the invention is characterized in that, in the case of alternative (i1) of claim 1, a supply and distribution system for the carbon dioxide-rich gas stream containing carbon monoxide is provided, separate from the operating gases of the burners and separately switchable, switchable, or controllable. In this way, the burner operation is disturbed as little as possible, since the fuel gas stream and the portion of the carbon dioxide-rich gas stream returned to the burners can be controlled separately.

[0026] A third aspect of the method according to the invention is characterized in that, in the case of alternatives (i3) or (i4) of claim 1, a catalyst zone is provided in the flue gas duct and / or in the flue gas stack, wherein the catalyst zone contains a catalyst active for the catalytic oxidation of carbon monoxide with oxygen to carbon dioxide. Since the flue gas temperature at these inlet points is lower than in the burners, the concentration of carbon monoxide can be effectively reduced by means of catalytic oxidation.

[0027] A fourth aspect of the process according to the invention is characterized in that the oxygen required for the catalytic oxidation of carbon monoxide is not introduced separately into the flue gas duct or flue gas stack, but rather that only the residual oxygen present in the flue gas stream is used as the oxygen-containing oxidizing agent. The residual oxygen content exceeds the CO concentration many times over, so that this measure eliminates the need for separate supply lines for oxygen as an oxidizing agent for the catalytic oxidation of carbon monoxide.

[0028] A fifth aspect of the process according to the invention is characterized in that the catalyst zone contains at least one catalyst active for the catalytic oxidation of carbon monoxide with oxygen to carbon dioxide, which is selected from the group consisting of: catalyst beds made of particulate catalysts, catalytic wire meshes, honeycomb catalysts, structured packing catalysts.

[0029] Due to the large number of commercially available catalysts, the optimal catalyst for the respective application with regard to pressure loss and catalyst activity can be selected.

[0030] A sixth aspect of the method according to the invention is characterized in that the catalyst zone (a) contains at least one catalyst active for the catalytic oxidation of carbon monoxide with oxygen to carbon dioxide, which is also active for the selective catalytic reduction (SCR) of nitrogen oxides, or (b) contains at least one first catalyst active for the catalytic oxidation of carbon monoxide with oxygen to carbon dioxide and at least one second catalyst active for the selective catalytic reduction (SCR) of nitrogen oxides. Aspect (a) is particularly advantageous because it eliminates the need for a separate catalyst for catalytic CO oxidation, allowing the existing SCR catalyst to be used. Common SCR catalysts, for example those based on vanadium pentoxide, also exhibit activity for catalytic CO oxidation.

[0031] A seventh aspect of the process according to the invention is characterized in that, in the flow path of the carbon dioxide-enriched detergent stream between the absorption column and the hot regeneration device, there is no separate flash stage for separating a carbon monoxide-containing flash gas from the carbon dioxide-enriched detergent stream. The separate flash stage can be omitted due to the treatment of the carbon dioxide-enriched detergent stream according to the invention, thereby reducing the investment costs and the space required for a corresponding plant.

[0032] An eighth aspect of the process according to the invention is characterized in that a third part of the carbon dioxide-rich gas stream containing carbon monoxide is released into the environment. This increases the operational reliability of the process and the corresponding plant, since in the event of malfunctions in individual process steps, a portion of the carbon dioxide-rich gas stream can be temporarily released into the environment as an emergency measure.

[0033] A ninth aspect of the invention relates to the system according to claim 9.

[0034] In a tenth aspect of the invention, the system is characterized in that, in the case of alternative (i1) in claim 9, a supply and distribution system for the carbon dioxide-rich gas stream containing carbon monoxide is included, which is separate from the operating gases of the burners and can be switched on or off or controlled separately. The advantages obtained in this aspect of the invention correspond to those discussed in connection with the second aspect of the invention.

[0035] In an eleventh aspect of the invention, the system is characterized in that, in the case of alternatives (i3) or (i4) in claim 9, a catalyst zone is included in the flue gas duct and / or in the flue gas stack, wherein the catalyst zone contains a catalyst active for the catalytic oxidation of carbon monoxide with oxygen to carbon dioxide. The advantages obtained in this aspect of the invention correspond to those discussed in connection with the third aspect of the invention.

[0036] In a twelfth aspect of the invention, the apparatus is characterized in that the catalyst zone contains at least one catalyst active for the catalytic oxidation of carbon monoxide with oxygen to carbon dioxide, selected from the group consisting of: catalyst beds made of particulate catalysts, catalytic wire meshes, honeycomb catalysts, and structured packing catalysts. The advantages obtained in this aspect of the invention correspond to those discussed in connection with the fifth aspect of the invention.

[0037] In a thirteenth aspect of the invention, the plant is characterized in that the catalyst zone (a) comprising at least one catalyst active for the catalytic oxidation of carbon monoxide with oxygen to carbon dioxide, which is also active for the selective catalytic reduction (SCR) of nitrogen oxides, or (b) comprising at least one first catalyst active for the catalytic oxidation of carbon monoxide with oxygen to carbon dioxide, and at least one second catalyst active for the selective catalytic reduction (SCR) of nitrogen oxides. The advantages obtained in this aspect of the invention correspond to those discussed in connection with the sixth aspect of the invention.

[0038] In a fourteenth aspect of the invention, the system is characterized in that, in the flow path of the carbon dioxide-enriched detergent stream between the absorption column and the hot regeneration device, there is no separate flash stage for separating a carbon monoxide-containing flash gas from the carbon dioxide-enriched detergent stream. The advantages obtained in this aspect of the invention correspond to those discussed in connection with the seventh aspect of the invention. Example of implementation

[0039] Further developments, advantages, and possible applications of the invention will also become apparent from the following description of exemplary embodiments and the drawings. All features described and / or illustrated, whether individually or in any combination, constitute the invention, irrespective of their compilation in the claims or their cross-reference.

[0040] They show: Fig. 1 an example of a steam reforming process or a corresponding plant for producing a synthesis gas product stream according to the state of the art, in which a carbon dioxide rich gas stream containing carbon monoxide is released into the atmosphere; Fig. 2 an example of a steam reforming process or a corresponding plant for producing a synthesis gas product stream according to the state of the art, in which CO emission is reduced by a flash stage placed between the absorption step and the desorption step; Fig. 3 an example of a steam reforming process or a corresponding plant for producing a synthesis gas product stream in which CO emissions are reduced according to a first embodiment of the invention; Fig. 4an example of a steam reforming process or a corresponding plant for producing a synthesis gas product stream in which CO emissions are reduced according to a second embodiment of the invention; Fig. 5 an example of a steam reforming process or a corresponding plant for producing a synthesis gas product stream in which CO emissions are reduced according to a third embodiment of the invention.

[0041] Fig. 1 shows an example of a steam reforming process or a corresponding plant for producing a synthesis gas product stream according to the state of the art, in which CO emission is reduced by a flash stage placed between the absorption step and the desorption step.

[0042] In Fig. 1The reformer furnace 10 contains a multitude of catalyst-filled reformer tubes 11. Typically, there are several hundred reformer tubes; for clarity, only four are shown in the figure. The catalyst used is a commercially available, nickel-based steam reforming catalyst. Preheated, hydrocarbon-containing natural gas is fed into the reformer tubes as the reformer feed via lines 16, 76, and 12. The inlet temperature of the reformer feed is, for example, 500 °C. Before the reformer feed enters the reformer, steam is added to it (not shown in the figure) to achieve a defined steam / carbon ratio of, for example, 3 mol / mol.After the feedstock is converted in the reformer tubes, the gaseous reformer product containing hydrogen, CO and unreacted natural gas components is drawn off via lines 13 and 42 and cooled in the heat exchanger 44, whereby a cooled raw synthesis gas is obtained as the reformer product and discharged via line 46.

[0043] The reformer tubes are fired by means of a plurality of burners 14, which are mounted on the top of the reformer furnace and heat the space between the reformer tubes. For clarity, only five burners are shown in the figure. In the example of the Fig. 1 The burners 14 are operated with natural gas and / or combustible gases from the synthesis gas processing plant as fuel gas. The fuel gas is supplied to the burners via line 15 and distribution lines 17. Additionally, preheated combustion air is mixed with the fuel gas and / or introduced into the burners 14 (not shown in the image).

[0044] In the reformer furnace 10, heat is transferred to the reformer tubes by thermal radiation from the burner flames and by convective heat transfer from the hot flue gases. After heat transfer, the flue gases enter the waste heat section 18 of the reformer furnace 10. The flue gases are conveyed through the waste heat section of the reformer furnace via line 22 in the induced draft of the blower 20. In the waste heat section of the reformer furnace, the flue gases are further cooled by several heat exchangers in the flue gas path, whereby the enthalpy of the flue gases is used to preheat several feed streams, for example, the reformer insert and the combustion air (not shown in the diagram). The cooled flue gases are then fed via line 24 to the flue gas stack 30 and released into the atmosphere.

[0045] The cooled raw synthesis gas is fed via line 46 to an absorption column 50 and introduced into it. If maximizing the hydrogen yield is the primary process objective, the hydrogen content in the raw synthesis gas is optionally (not shown in the illustration) increased before being introduced into the absorption column by carrying out CO conversion (water-gas shift (WGS) reaction) using added steam over a suitable catalyst according to the conversion equation CO + H₂O = H₂ + CO₂. This reduces the carbon monoxide content in the raw synthesis gas and increases the carbon dioxide content according to the stoichiometry of the WGS reaction.

[0046] Gas scrubbing in absorption column 50 is carried out in a manner known per se by contacting the raw synthesis gas with a CO₂-selective scrubbing agent or absorbent, for example, an amine-containing scrubbing agent, or in one example, a scrubbing agent containing methyldiethanolamine (MDEA). A carbon dioxide-depleted synthesis gas product stream is discharged from absorption column 50 via line 54 and fed to further purification, conditioning, or use.

[0047] The carbon dioxide-laden detergent is discharged from the absorption column 50 via line 52 and fed into the regeneration unit 60. In the regeneration unit 60, the detergent is regenerated by pressure reduction (flashing) and hot regeneration via stripping with its own steam. A regenerated detergent stream is discharged from the regeneration unit 60 via line 62 and, after optional cooling and pressure increase (both not shown), is fed into the absorption column 50.

[0048] A carbon dioxide-rich gas stream, still containing a significant proportion of carbon monoxide, is discharged from the regeneration device 60 via line 64 and introduced into a gas-liquid phase separator 66. In the gas-liquid phase separator 66, liquid components of the detergent still contained in the carbon dioxide-rich gas stream are separated and returned to the regeneration device 60 via line 68.

[0049] The carbon dioxide-rich gas stream, which still contains a significant proportion of carbon monoxide, is discharged from the gas-liquid phase separator 66 via line 69. A first portion of the carbon monoxide-containing carbon dioxide-rich gas stream is released into the atmosphere via line 70. A second portion of the carbon monoxide-containing carbon dioxide-rich gas stream is returned via line 72, compressor 74, and lines 76 and 12 to the reformer tubes 11, where it is partially converted to carbon monoxide and thus utilized as a material.

[0050] The release of the first part of the carbon monoxide-containing carbon dioxide-rich gas stream into the atmosphere is problematic whenever its CO concentration exceeds the permissible emission limit for carbon monoxide. Such a case is therefore shown in... Fig. 2 .

[0051] In the Figures 2 to 5Elements with the same reference symbols correspond to the elements and their use, function, and properties related to Fig. 1 were explained.

[0052] Unlike Fig. 1 is in Fig. 2 A flash stage 80 is arranged between absorption column 50 and regeneration unit 60. The carbon dioxide-laden detergent is discharged from absorption column 50 via line 52 and introduced into the flash stage 80. Due to the rapid pressure drop, a gas phase is obtained in the flash stage containing the majority of the carbon monoxide that was previously dissolved in the carbon dioxide-laden detergent. The carbon monoxide-depleted, carbon dioxide-laden detergent is discharged from the flash stage 80 via line 85 and introduced into the regeneration unit 60.

[0053] The carbon monoxide-containing gas phase is discharged from flash stage 80 via line 81 and returned to burners 14 via lines 82 and 15, where it reacts with fuel gas and combustion air. This reduces the CO content through thermal post-oxidation. The resulting flue gases are treated as described in connection with... Fig. 1 explained, released into the atmosphere.

[0054] The disadvantages of the in Fig. 2 The method shown involves additional investment costs and space requirements for the flash stage. Therefore, an objective of the present invention is to eliminate the need for such a flash stage while simultaneously reducing CO emissions into the atmosphere.

[0055] Therefore, according to Fig. 3In a first embodiment of the invention, the first part of the carbon monoxide-containing carbon dioxide-rich gas stream is not released to the atmosphere via line 70, but is returned to the burners 14 via lines 70, 81, and 82, where it is reacted together with fuel gas and combustion air. In this way, the CO content is reduced by thermal post-oxidation. The flue gases produced in this process are treated as in connection with Fig. 1The carbon monoxide is released into the atmosphere. The first part of the carbon dioxide-rich gas stream, containing carbon monoxide, can, for example, be introduced into line 15 or, in another example, introduced into the burners via a separate supply and distribution system (so-called header). The latter approach is advantageous because the supply of fuel gas and combustion air to the burners, on the one hand, and with the first part of the carbon monoxide-containing carbon dioxide-rich gas stream, on the other, is independent of each other. This enables trouble-free burner operation and good, independent control of the gas flows.

[0056] The second part of the carbon monoxide-containing carbon dioxide-rich gas stream is processed as in Fig. 1 via line 72, compressor 74, lines 76 and 12 back to the reformer tubes 11, in which it is partially converted to carbon monoxide and thus used as a material.

[0057] In a second embodiment of the invention, according to Fig. 4 The first part of the carbon dioxide-rich gas stream is not released into the atmosphere, but is returned to the reformer furnace via lines 81 and 82 and introduced into it. This introduction can occur into the reformer furnace 10 (indicated by a dashed arrow) and / or into the waste heat section 18 (line 82, solid arrow), which is connected to it by fluid. When introduced into the hot section of the reformer furnace, the carbon monoxide undergoes spontaneous afterburning. When introduced into the waste heat section 18, an oxidation catalyst 90 can optionally be provided to catalyze the CO oxidation to carbon dioxide. It is particularly advantageous to utilize an existing catalyst for the selective catalytic reduction (SCR) of nitrogen oxides in the reforming flue gas for the CO oxidation.

[0058] The second part of the carbon monoxide-containing carbon dioxide-rich gas stream is processed as in Fig. 1 via line 72, compressor 74, lines 76 and 12 back to the reformer tubes 11, in which it is partially converted to carbon monoxide and thus used as a material.

[0059] In a third embodiment of the invention, according to Fig. 5 The first part of the carbon dioxide-rich gas stream is not released into the atmosphere, but is routed via lines 81, 82, and 83 to the flue gas stack 30 and introduced into it. Since the temperature of the reforming flue gas has already been significantly reduced in the flue gas stack, it is generally necessary to provide an oxidation catalyst 90, which catalyzes the CO oxidation to carbon dioxide.

[0060] The second part of the carbon monoxide-containing carbon dioxide-rich gas stream is processed as in Fig. 1via line 72, compressor 74, lines 76 and 12 back to the reformer tubes 11, in which it is partially converted to carbon monoxide and thus used as a material.

[0061] In the embodiments of the invention according to Fig. 3 , 4 or 5 It is particularly advantageous if the oxygen required for the catalytic oxidation of carbon monoxide is not introduced separately into the flue gas duct or flue gas stack, but rather if only the residual oxygen present in the flue gas stream is used as the oxygen-containing oxidizing agent. The residual oxygen content in the flue gas stream exceeds the CO concentration many times over, so that this measure eliminates the need for separate oxygen supply lines for the catalytic oxidation of carbon monoxide.

[0062] Modifications to the embodiments of the present disclosure described above are possible without departing from the scope of the present disclosure as defined by the appended claims. Terms such as "including," "comprising," "containing," "have," and "is," used to describe and claim the present disclosure, are to be understood in a non-exclusive manner, i.e., they permit the presence of items, components, or elements not expressly described. References to the singular are to be understood as also referring to the plural unless expressly stated otherwise in a specific case. Reference symbol list

[0063]

[10] Reformer furnace

[11] Reformer tubes

[12] Line

[13] Line

[14] Burner

[15] Line

[16] Line

[17] Line

[18] Waste heat section of the reformer furnace

[20] Flue gas blower

[22] Line

[24] Line

[30] Flue gas stack

[42] Line

[44] Heat exchanger

[46] Line

[50] Absorption column

[52] Line

[54] Line

[60] Regeneration device

[62] Line

[64] Line

[66] Gas-liquid phase separator

[68] Line

[69] Line

[70] Line

[72] Line

[74] Compressor

[76] Line

[80] Flash stage

[81] Line

[82] Line

[83] Line

[85] Line

[90] CO oxidation catalyst

Claims

1. A method for producing a synthesis gas product stream, which contains hydrogen, carbon monoxide and carbon dioxide, by steam reforming of a hydrocarbon-containing feed stream with a reforming steam stream in a steam reformer, wherein the method comprises the following steps: (a) providing a steam reformer, comprising: (a1) a plurality of reformer tubes filled with a steam reforming catalyst with means for introducing the hydrocarbon-containing feed stream and the reforming steam stream into the reformer tubes and with means for discharging a raw synthesis gas stream from the reformer tubes; (a2) a reformer furnace with a floor, a ceiling and side walls, which form a furnace interior, wherein the reformer tubes are arranged within the furnace interior and are heated by a plurality of burners; (a3) a flue gas line, which is in fluid communication with the furnace interior through one of the side walls; (b) providing the hydrocarbon-containing feed stream and a reforming steam stream and introducing the hydrocarbon-containing feed stream and the reforming steam stream into the reformer tubes; (c) providing a fuel gas stream and an oxygen-containing oxidant stream and introducing the fuel gas stream and the oxygen-containing oxidant stream into the burners, combusting the fuel gas stream with the oxygen-containing oxidant stream in the burners and thereby heating the reformer tubes and generating a flue gas stream; (d) reacting the hydrocarbon-containing feed stream with the reforming steam stream under steam reforming conditions in the reformer tubes to the raw synthesis gas stream, which contains hydrogen, carbon monoxide, carbon dioxide, unreacted steam and unreacted hydrocarbons, discharging the raw synthesis gas stream from the reformer tubes and from the steam reformer; (e) discharging the flue gas stream from the furnace interior through the flue gas line and introducing the flue gas stream or a treated flue gas stream into a flue gas stack, which is in fluid communication with the flue gas line; (f) introducing the raw synthesis gas stream into a cooling device, cooling the raw synthesis gas stream in the cooling device, discharging a cooled raw synthesis gas stream from the cooling device; (g) introducing the cooled raw synthesis gas stream into an absorption column for separating carbon dioxide, bringing the cooled raw synthesis gas stream into contact in the absorption column with an amine-containing scrubbing liquid stream in counter-current under conditions of chemisorptive gas scrubbing (absorption), discharging a raw synthesis gas stream depleted in carbon dioxide as a synthesis gas product stream from the absorption column, discharging a scrubbing liquid stream enriched in carbon dioxide and carbon monoxide from the absorption column at its lower end; (h) introducing the scrubbing liquid stream enriched in carbon dioxide and carbon monoxide into a hot regeneration device, hot regenerating the partially regenerated scrubbing liquid stream enriched in carbon dioxide under hot regeneration conditions by stripping with autogenous steam and / or a stripping gas stream in the hot regeneration device, discharging a hot regenerated scrubbing liquid stream from the hot regeneration device, introducing at least a part of the hot regenerated scrubbing liquid stream into the absorption column as an amine-containing scrubbing liquid stream, discharging a carbon monoxide-containing carbon dioxide-rich gas stream from the hot regeneration device; (i) introducing at least a first part of the carbon monoxide-containing carbon dioxide-rich gas stream (i1) into the reformer furnace via at least one burner and / or (i2) into the reformer furnace outside of the burners and at a point in the reformer furnace at which the local gas temperature is at least 1000 °C and / or (i3) into the flue gas line and / or (i4) into the flue gas stack; (j) introducing a second part of the carbon monoxide-containing carbon dioxide-rich gas stream into the reformer tubes.

2. The method according to claim 1, characterized in that in the case of alternative (i1), a supply and distribution system for the carbon monoxide-containing carbon dioxide-rich gas stream, which is separate from the operating gases of the burners, and which can be separately switched on or off or regulated, is provided.

3. The method according to claim 1, characterized in that in the case of alternatives (13) or (i4), a catalyst zone is provided in the flue gas line and / or in the flue gas stack, wherein the catalyst zone contains a catalyst active for the catalytic oxidation of carbon monoxide with oxygen to carbon dioxide.

4. The method according to claim 3, characterized in that the oxygen required for the catalytic oxidation of carbon monoxide is not introduced separately into the flue gas line or into the flue gas stack, but that exclusively the residual oxygen present in the flue gas stream is used as the oxygen-containing oxidizing agent.

5. The method according to claim 3 or 4, characterized in that the catalyst zone contains at least one catalyst active for the catalytic oxidation of carbon monoxide with oxygen to carbon dioxide, which is selected from the group consisting of: catalyst beds of particulate catalysts, catalytic wire gauzes, honeycomb catalysts, structured packing catalysts.

6. The method according to any one of claims 3 to 5, characterized in that the catalyst zone (a) contains at least one catalyst active for the catalytic oxidation of carbon monoxide with oxygen to carbon dioxide, which is also active for the selective catalytic reduction (SCR) of nitrogen oxides, or (b) contains at least a first catalyst which is active for the catalytic oxidation of carbon monoxide with oxygen to carbon dioxide, and at least a second catalyst which is active for the selective catalytic reduction (SCR) of nitrogen oxides.

7. The method according to any one of the preceding claims, characterized in that in the flow path of the scrubbing liquid stream enriched with carbon dioxide between the absorption column and the hot regeneration device, no separate flash stage for separating a carbon monoxide-containing flash gas from the scrubbing liquid stream enriched with carbon dioxide is present.

8. The method according to any one of the preceding claims, characterized in that a third part of the carbon monoxide-containing carbon dioxide-rich gas stream is released to the environment.

9. An apparatus for producing a synthesis gas, which contains hydrogen and carbon oxides, by steam reforming of a hydrocarbon-containing feed stream with a reforming steam stream in a steam reformer, wherein the apparatus comprises the following components and assemblies, which are in fluid communication with each other: (a) a steam reformer, comprising: (a1) a plurality of reformer tubes filled with a steam reforming catalyst with means for introducing the hydrocarbon-containing feed stream and the reforming steam stream into the reformer tubes and with means for discharging a raw synthesis gas stream from the reformer tubes; (a2) a reformer furnace with a floor, a ceiling and side walls, which form a furnace interior, wherein the reformer tubes are arranged within the furnace interior and are heated by a plurality of burners; (a3) a flue gas line, which is in fluid communication with the furnace interior through one of the side walls; (b) means for providing the hydrocarbon-containing feed stream and a reforming steam stream and means for introducing the hydrocarbon-containing feed stream and the reforming steam stream into the reformer tubes; (c) means for providing a fuel gas stream and an oxygen-containing oxidant stream and means for introducing the fuel gas stream and the oxygen-containing oxidant stream into the burners; (d) means for discharging a raw synthesis gas stream, which contains hydrogen, carbon monoxide, carbon dioxide, unreacted steam and unreacted hydrocarbons, from the reformer tubes and from the steam reformer; (e) a flue gas stack, which is in fluid communication with the flue gas line, means for discharging a flue gas stream from the furnace interior through the flue gas line and means for introducing the flue gas stream or a treated flue gas stream into the flue gas stack; (f) a cooling device, means for introducing the raw synthesis gas stream into the cooling device, means for discharging a cooled raw synthesis gas stream from the cooling device; (g) an absorption column for separating carbon dioxide, means for introducing the cooled raw synthesis gas stream into the absorption column at its lower end, means for introducing an amine-containing scrubbing liquid stream into the absorption column, means for discharging a raw synthesis gas stream depleted in carbon dioxide as a synthesis gas product stream from the absorption column at its upper end, means for discharging a scrubbing liquid stream enriched in carbon dioxide and carbon monoxide from the absorption column at its lower end; (h) a hot regeneration device, means for introducing the scrubbing liquid stream enriched in carbon dioxide into the hot regeneration device, means for discharging a hot regenerated scrubbing liquid stream from the hot regeneration device, means for introducing at least a part of the hot regenerated scrubbing liquid stream into the absorption column as an amine-containing scrubbing liquid stream, means for discharging a carbon monoxide-containing carbon dioxide-rich gas stream from the hot regeneration device; (i) means for introducing at least a part of the carbon monoxide-containing carbon dioxide-rich gas stream (i1) into the reformer furnace via at least one burner and / or (i2) into the reformer furnace outside of the burners and at a point in the reformer furnace at which the local gas temperature is at least 1000 °C and / or (i3) into the flue gas line and / or (i4) into the flue gas stack; (j) means for introducing a second part of the carbon monoxide-containing carbon dioxide-rich gas stream into the reformer tubes.

10. The apparatus according to claim 9, characterized in that in the case of alternative (i1), it comprises a supply and distribution system for the carbon monoxide-containing carbon dioxide-rich gas stream, which is separate from the operating gases of the burners and which can be separately switched on or off or regulated.

11. The apparatus according to claim 9, characterized in that in the case of alternatives (i3) or (i4), it comprises a catalyst zone in the flue gas line and / or in the flue gas stack, wherein the catalyst zone contains a catalyst active for the catalytic oxidation of carbon monoxide with oxygen to carbon dioxide.

12. The apparatus according to claim 11, characterized in that the catalyst zone contains at least one catalyst active for the catalytic oxidation of carbon monoxide with oxygen to carbon dioxide, which is selected from the group consisting of: catalyst beds of particulate catalysts, catalytic wire gauzes, honeycomb catalysts, structured packing catalysts.

13. The apparatus according to claim 11 or 12, characterized in that the catalyst zone (a) contains at least one catalyst active for the catalytic oxidation of carbon monoxide with oxygen to carbon dioxide, which is also active for the selective catalytic reduction (SCR) of nitrogen oxides, or (b) contains at least a first catalyst which is active for the catalytic oxidation of carbon monoxide with oxygen to carbon dioxide, and at least a second catalyst which is active for the selective catalytic reduction (SCR) of nitrogen oxides.

14. The apparatus according to any one of claims 11 to 13, characterized in that in the flow path of the scrubbing liquid stream enriched with carbon dioxide between the absorption column and the hot regeneration device, no separate flash stage for separating a carbon monoxide-containing flash gas from the scrubbing liquid stream enriched with carbon dioxide is present.