Process and apparatus for converting sulfur dioxide into sulfur trioxide

Description

1 / 27 PROCESS AND APPARATUS FOR CONVERTING SULFUR DIOXIDE INTO SULFUR TRIOXIDE FIELD OF TECHNIQUE

[0001] The present embodiments relate to a process and apparatus for producing sulfuric acid. The illustrative embodiments relate to a process and apparatus for preparing sulfur trioxide from a stream containing sulfur dioxide. BACKGROUND OF THE INVENTION

[0002] A sulfuric acid regeneration plant oxidizes feed streams containing sulfur in a furnace to produce a process gas consisting primarily of sulfur dioxide, which is subsequently routed through gas conditioning and thermal recovery equipment.

[0003] After the sulfur-containing process gas exits the gas conditioning equipment, it will consist mainly of dry, low-temperature sulfur dioxide. Known processes mix ambient air (such as atmospheric air) or dry air with the sulfur dioxide-containing process gas to allow the sulfur dioxide to be fully oxidized to sulfur trioxide as the gas passes through one or more catalyst beds in a catalytic converter.

[0004] The gas mixture containing sulfur dioxide and atmospheric air must be maintained at a suitable temperature to promote the oxidation reaction before entering each bed of the catalytic converter. The temperature of the mixture can be adjusted by a heat exchanger. The heat exchanger Petition 870250108202, dated 11 / 26 / 2025, page 5 / 40 2 / 27 may have limited capacity, and therefore an attempt to increase production causes the final temperature of the mixture to be unable to adequately promote the oxidation reaction necessary to produce sulfur trioxide.

[0005] Increasing the volumetric gas flow rate of the gas mixture entering the catalytic converter has two additional negative impacts on the process. First, it increases the pressure drop across the catalyst, and in many cases, the process is already limited by fan capacity. Second, the increased volumetric flow rate lowers the residence time in the catalytic converter, which lowers conversion efficiency and leads to larger quantities of unreacted sulfur dioxide exiting the converter and being emitted into the atmosphere.

[0006] The oxidation of sulfur dioxide in the converter is an exothermic reaction, and therefore, increasing the amount of sulfur dioxide entering the converter will result in more heat being generated. A newer catalytic converter is typically divided into multiple stages so that heat can be removed between each catalytic stage to maintain the appropriate reaction temperature range at each stage. The gases first pass through the catalyst bed and are then conducted through a heat exchanger to reduce the temperature before they return to pass through the next catalyst bed. Older versions of catalytic converters may include only a single catalyst bed and no heat exchanger to regulate the temperature of an outgoing gas stream.

[0007] A sulfuric acid plant equipment mechanism that is operating at design capacity is Petition 870250108202, dated 11 / 26 / 2025, page 6 / 40 3 / 27 limited by multiple operational constraints, including the pressure drop created by the gases moving through the system and the system's ability to maintain gas temperatures at ideal levels to promote the reactions. Furthermore, if the amount of sulfur dioxide introduced into the catalytic converter increases, the capacity of the heat exchangers may not be sufficient to remove the additional heat generated; consequently, the resulting increased temperature of the process gas in the converter will limit the completeness of the reaction to sulfur trioxide based on the balance between sulfur trioxide formation and decomposition. SUMMARY OF THE INVENTION

[0008] In the present invention, a process is disclosed for replacing at least a portion of the oxidizing atmospheric air with oxygen that is mixed with a feed containing sulfur dioxide for oxidation to produce sulfur trioxide in a catalytic converter. The process may include mixing the oxygen with the sulfur dioxide stream before entering the initial catalytic region or stage of the catalytic converter and / or mixing the oxygen with the sulfur dioxide stream before introducing the sulfur dioxide stream into subsequent catalytic regions or stages of the catalytic converter.

[0009] According to an illustrative embodiment of the present invention, a process is provided for converting sulfur dioxide into sulfur trioxide, wherein the process includes (a) introducing a sulfur dioxide feed stream into a catalytic converter to convert sulfur dioxide into sulfur trioxide, (b) introducing a stream Petition 870250108202, dated 11 / 26 / 2025, page 7 / 40 4 / 27 of oxygen-enriched feed, a pure oxygen feed stream, or both the oxygen-enriched feed stream and the pure oxygen feed stream in the catalytic converter, and (c) catalytically oxidize at least a portion of the sulfur dioxide from the sulfur dioxide feed stream to produce sulfur trioxide.

[0010] According to another illustrative embodiment of the present invention, an apparatus is provided for converting sulfur dioxide into sulfur trioxide, wherein the apparatus includes a housing, an inlet to the housing for supplying a feed containing sulfur dioxide in the housing, at least one catalytic region positioned in the housing for converting sulfur dioxide into sulfur trioxide, and at least one inlet for supplying a feed stream of oxygen-enriched combustion air or a feed stream of pure oxygen in the feed containing sulfur dioxide.

[0011] The summary of the invention above is intended to be a brief introduction to certain illustrative embodiments of the invention and should not be considered in any way as limiting the scope of the appended claims. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] For a more complete understanding of the present invention, reference may be made to the following description of the exemplary embodiments considered in conjunction with the Figures of the accompanying drawings, in which: Figure 1 is a schematic representation of a known sulfuric acid production plant that has a catalytic converter to convert sulfur dioxide from a Petition 870250108202, dated 11 / 26 / 2025, page 8 / 40 5 / 27 current supply in sulfur trioxide. Figure 2 is a schematic representation of a known multi-stage catalytic converter section of a sulfuric acid production plant for converting sulfur dioxide from a feed stream into sulfur trioxide, as shown in Figure 1. Figure 3 is a schematic representation of an illustrative embodiment of the multi-stage catalytic converter presently disclosed for converting sulfur dioxide from a feed stream into sulfur trioxide. Figure 4 is a schematic representation of another illustrative embodiment of the multi-stage catalytic converter presently disclosed for converting sulfur dioxide from a feed stream into sulfur trioxide. Figure 5 is a schematic representation of another illustrative embodiment of the multi-stage catalytic converter presently disclosed for converting sulfur dioxide from a feed stream into sulfur trioxide. DETAILED DESCRIPTION

[0013] Before explaining the inventive embodiments in detail, it should be understood that the invention is not limited, in its application, to the details of construction and arrangement of parts illustrated in the accompanying drawings, if any, since the invention may have other embodiments and be practiced or carried out in various ways. Furthermore, it should be understood that the phraseology or terminology employed in the present invention is for descriptive purposes and not for limitation.

[0014] In the following description, terms such as horizontal, standing, vertical, above, below, under and similar terms, Petition 870250108202, dated 11 / 26 / 2025, p. 9 / 40 6 / 27 should be used solely for the purpose of clarity to illustrate the invention and should not be considered as expressions of limitation. The drawings are intended for the purpose of illustrating the invention and are not intended to be placed to scale.

[0015] The reference, in the following description, to “one or more” may be considered to include one or a plurality of”. The reference, in the following description, to “ambient air” may include, for example, “atmospheric air” or “dry air”.

[0016] In the following description, references to "entry" and "exit" relate to fluid communication or the movement of a substance or fluid (liquid or gas) within and outside a structure, respectively. Such entry and / or exit can be achieved through openings, doors, orifices, pipes, conduits, weirs, or other similar structures, such as injectors or sprinklers.

[0017] The description contained in the present invention that refers to at least one catalytic region or stage with one or more heat exchangers is not intended to exclude the older single-catalyst bed version that does not include a heat exchanger.

[0018] A process and apparatus for converting sulfur dioxide into sulfur trioxide are disclosed. The process and apparatus utilize oxygen to replace some or all of the atmospheric air that is mixed with the sulfur dioxide stream for oxidation to sulfur trioxide in the catalytic converter.

[0019] The replacement of at least a portion of Petition 870250108202, dated 11 / 26 / 2025, page 10 / 40 7 / 27 Atmospheric air replaced by oxygen maintains or reduces the total volume of the gas mixture, which allows for the processing of more sulfur dioxide with the same amount of pressure drop and residence time, while also maintaining the ability of the catalytic converter heat exchangers to lower the temperature to that required to promote the oxidation reaction of sulfur dioxide into sulfur trioxide in the catalytic converter.

[0020] Replacing at least a portion of atmospheric air with oxygen also increases the partial pressure of oxygen and sulfur dioxide and promotes the rate of conversion of sulfur dioxide to sulfur trioxide through the catalyst in the catalytic region of the catalytic converter.

[0021] At least a portion of the oxygen replacement may be introduced into suitable piping or tubing before entering the catalytic converter housing to ensure proper mixing with the remaining atmospheric air and sulfur dioxide before contacting the catalyst in the initial catalytic stage or region of the converter. The process also provides for the retention of all or a portion of the oxygen replacement from the initial catalytic stage or region and its mixing with the sulfur dioxide gas stream before entering the catalytic stages or regions that are positioned downstream of the initial catalytic stage or region.

[0022] The oxygen introduced in the initial catalyst stage or region is controlled to manage the amount of heat released by the exothermic sulfur dioxide oxidation reaction. The remaining oxygen replacement can then be introduced into the gas stream. Petition 870250108202, dated 11 / 26 / 2025, page 11 / 40 8 / 27 process in subsequent stages of the converter, downstream of the heat exchanger and before entering subsequent catalyst stages for the purpose of managing the gas temperature and maintaining the appropriate reaction temperature at that stage of the converter.

[0023] The process increases the capacity of the catalytic converter in a sulfuric acid plant by replacing some or all of the oxidizing air portion with oxygen, while maintaining conversion and energy efficiency. The process for converting sulfur dioxide to sulfur trioxide comprises introducing a sulfur dioxide feed stream into a catalytic converter to convert sulfur dioxide to sulfur trioxide, introducing an oxygen-enriched feed stream, a pure oxygen feed stream, or both an oxygen-enriched feed stream and a pure oxygen feed stream into the catalytic converter, and oxidizing at least a portion of the sulfur dioxide from the sulfur dioxide feed stream to produce sulfur trioxide.

[0024] According to certain illustrative embodiments, the process comprises adding an oxygen-enriched feed stream to the catalytic converter. According to other illustrative embodiments, the process comprises adding a pure oxygen feed stream to the catalytic converter. According to further illustrative embodiments, the process comprises adding both an oxygen-enriched feed stream and a pure oxygen feed stream to the catalytic converter. Petition 870250108202, dated 11 / 26 / 2025, page 12 / 40 9 / 27

[0025] The process for converting sulfur dioxide into sulfur trioxide utilizes a catalytic converter. The catalytic converter used in the process comprises a housing that has at least one catalytic region positioned within the housing that is capable of catalytically oxidizing at least a portion of the sulfur dioxide from the sulfur dioxide feed stream that is introduced into the catalytic converter. The catalytic converter also comprises at least one heat exchanger for removing thermal energy from the stream that is generated during the process for converting sulfur dioxide into sulfur trioxide.

[0026] According to certain illustrative embodiments, the catalytic converter used in the process to convert sulfur dioxide into sulfur trioxide comprises a housing that has more than one catalytic region (or a plurality of catalytic regions) positioned within the housing, wherein each region is capable of catalytically oxidizing at least a portion of the sulfur dioxide from the sulfur dioxide feed stream introduced into the catalytic converter and into one or more heat exchangers to remove thermal energy generated as a result of the conversion process in the catalytic converter.The catalytic converter includes an upstream supply current inlet containing sulfur dioxide to introduce the supply current containing sulfur dioxide into the catalytic converter housing for catalytic conversion to sulfur trioxide, and a downstream supply current outlet containing sulfur trioxide where the current containing sulfur trioxide exits the catalytic converter housing.

[0027] According to certain modalities Petition 870250108202, dated 11 / 26 / 2025, page 13 / 40 10 / 27 illustrative embodiments, one or more heat exchangers may be positioned inside the catalytic converter housing. According to other illustrative embodiments, one or more heat exchangers may be positioned outside the catalytic converter housing. According to further illustrative embodiments, at least one of the one or more heat exchangers is positioned inside the catalytic converter housing and at least one of the one or more heat exchangers is positioned outside the catalytic converter housing. One or more catalytic regions are in fluid communication with one or more heat exchangers by means of suitable fluid connections, such as, but not limited to, pipes, conduits, hoses, tubing, pipes and similar fluid connections.

[0028] According to certain illustrative, non-limiting embodiments, the catalytic converter used in the process to convert sulfur dioxide into sulfur trioxide comprises an elongated vessel having an upstream feed stream inlet containing sulfur dioxide located at one end of the housing to introduce the feed stream containing sulfur dioxide into the catalytic converter housing for catalytic conversion into sulfur trioxide, a downstream feed stream outlet containing sulfur trioxide located at the other end of the housing, such as, for example, an opposite end of the housing, where the stream containing sulfur trioxide exits the catalytic converter housing, and a length is defined between the inlet and outlet. The catalytic converter may include more than one catalytic region and one or a plurality of heat exchangers positioned along the Petition 870250108202, dated 11 / 26 / 2025, p. 14 / 40 11 / 27 length of the housing between the inlet and outlet of the housing. According to certain embodiments, more than one catalytic region and one or more heat exchangers may be arranged in an alternating pattern along the length of the catalytic converter housing.

[0029] The process for converting sulfur dioxide into sulfur trioxide comprises introducing an oxygen-enriched feed stream, a pure oxygen feed stream, or both an oxygen-enriched feed stream and a pure oxygen feed stream into the catalytic converter at least at the inlet position along a length of the catalytic converter. According to certain embodiments, the process for converting sulfur dioxide into sulfur trioxide comprises introducing an oxygen-enriched feed stream, a pure oxygen feed stream, or both an oxygen-enriched feed stream and a pure oxygen feed stream into the catalytic converter at a position upstream of a first catalytic region of the catalytic converter.According to illustrative embodiments, the oxygen-enriched feed stream, the pure oxygen feed stream, or both the oxygen-enriched feed stream and the pure oxygen feed stream can be introduced into the catalytic converter housing through the sulfur dioxide-containing feed stream inlet located upstream of the catalytic converter housing. This can be accomplished by introducing the oxygen-enriched feed stream and / or the pure oxygen feed stream into the... Petition 870250108202, dated 11 / 26 / 2025, page 15 / 40 12 / 27 The sulfur dioxide-containing feed stream is located upstream of the sulfur dioxide-containing inlet of the catalytic converter housing. The mixture of the sulfur dioxide-containing feed stream and the oxygen-enriched feed stream and / or the pure oxygen feed stream then enters the catalytic converter housing through the inlet.

[0030] According to other illustrative embodiments, the oxygen-enriched feed stream, the pure oxygen feed stream, or both the oxygen-enriched feed stream and the pure oxygen feed stream can be directly introduced into the catalytic converter housing through at least one inlet that is positioned on a side wall of the housing along the length of the catalytic converter.

[0031] According to certain illustrative embodiments, the process for converting sulfur dioxide into sulfur trioxide comprises introducing oxygen-enriched feed stream, pure oxygen feed stream, or both oxygen-enriched feed stream and pure oxygen feed stream into the catalytic converter through at least one inlet that is positioned in the side wall of the housing in a position that is located upstream of one or more heat exchangers.

[0032] According to certain illustrative embodiments, the process for converting sulfur dioxide into sulfur trioxide comprises introducing the oxygen-enriched feed stream, the stream of Petition 870250108202, dated 11 / 26 / 2025, page 16 / 40 13 / 27 pure oxygen feed or both oxygen-enriched feed stream and pure oxygen feed stream into the catalytic converter through at least one inlet that is positioned on the side wall of the housing in a position that is located downstream of one or more heat exchangers.

[0033] According to certain embodiments, the process for converting sulfur dioxide to sulfur trioxide comprises supplying at least one of a spent sulfuric acid stream or another sulfur-containing stream to a furnace, decomposing the spent sulfuric acid stream or other sulfur-containing stream in the furnace to form sulfur dioxide, introducing a sulfur dioxide feed stream into a catalytic converter to convert sulfur dioxide to sulfur trioxide, and catalytically oxidizing at least a portion of the sulfur dioxide from the sulfur dioxide feed stream to sulfur trioxide. The process for catalytically oxidizing sulfur dioxide to sulfur trioxide is carried out by any of the illustrative embodiments described in the present invention.

[0034] Furthermore, a process is disclosed for preparing sulfuric acid from at least one spent sulfuric acid stream or other sulfur-containing stream. The process comprises feeding at least one spent sulfuric acid stream or other sulfur-containing stream into a furnace, decomposing the at least one spent sulfuric acid stream or other sulfur-containing stream in the furnace to form sulfur dioxide, introducing a sulfur dioxide feed stream into a catalytic converter to convert sulfur dioxide into sulfur trioxide. Petition 870250108202, dated 11 / 26 / 2025, page 17 / 40 14 / 27 sulfur, catalytically oxidize at least a portion of the sulfur dioxide from the sulfur dioxide feed stream to sulfur trioxide and convert the sulfur trioxide to sulfuric acid. The process for catalytically oxidizing sulfur dioxide to sulfur trioxide is carried out by any of the illustrative embodiments described in the present invention.

[0035] Furthermore, in the present invention, an apparatus for use in the process of converting sulfur dioxide into sulfur trioxide is disclosed. The apparatus comprises a housing, at least one catalytic region for converting sulfur dioxide into sulfur trioxide positioned within the housing, at least one heat exchanger, and at least one inlet for supplying a feed stream of oxygen-enriched combustion air or a feed stream of pure oxygen to the housing. According to certain embodiments, one or more inlets for supplying the oxygen-enriched combustion air feed stream and / or the pure oxygen feed stream to the housing are positioned upstream of a first catalytic region of the housing. These one or more inlets may be orifices located in the side walls of the catalytic converter housing.Alternatively, one or more inlets to supply the oxygen-enriched combustion air supply stream and / or pure oxygen supply stream to the housing are positioned upstream in fluid communication with the supply stream inlet containing sulfur dioxide, which is positioned upstream of the catalytic converter housing. The oxygen-enriched supply stream and / or pure oxygen supply stream sources... Petition 870250108202, dated 11 / 26 / 2025, page 18 / 40 15 / 27 pure oxygen feed lines are in fluid communication with piping that carries the feed stream containing sulfur dioxide at a position upstream of the sulfur dioxide inlet of the catalytic converter housing.

[0036] According to certain embodiments, one or more inlets to supply the oxygen-enriched combustion air feed stream and / or pure oxygen feed stream to the housing are positioned on the side wall of the housing in a position located upstream of one or more heat exchangers. According to certain embodiments, one or more inlets to supply the oxygen-enriched combustion air feed stream and / or pure oxygen feed stream to the housing are positioned on the side wall of the housing in positions located upstream of each of the one or more heat exchangers.

[0037] According to certain embodiments, one or more inlets to supply the oxygen-enriched combustion air feed stream and / or pure oxygen feed stream to the housing are positioned on the side wall of the housing in a position located upstream of one or more heat exchangers. According to certain embodiments, one or more inlets to supply the oxygen-enriched combustion air feed stream and / or pure oxygen feed stream to the housing are positioned on the side wall of the housing in positions located downstream of each of the one or more heat exchangers.

[0038] The device used in the process revealed Petition 870250108202, dated 11 / 26 / 2025, page 19 / 40 16 / 27 to regenerate sulfuric acid from a sulfur-containing feed stream includes a furnace to oxidize sulfur-containing feedstock into sulfur dioxide, a gas conditioning system to remove moisture and other impurities, a catalytic converter to oxidize sulfur dioxide into sulfur trioxide, and an acid tower in which sulfur trioxide is absorbed into recycled acid.

[0039] The sulfuric acid regeneration apparatus includes a decomposition furnace positioned upstream of the catalytic converter. The decomposition furnace comprises an inlet to supply at least one of a spent sulfuric acid stream or another stream containing sulfur into the decomposition furnace, an inlet to supply at least one of a combustion air feed stream, a combustion air feed stream enriched with oxygen, or a pure oxygen feed stream into the decomposition furnace, an inlet to supply a combustion fuel stream into the decomposition furnace, and an outlet for a stream containing sulfur dioxide. The catalytic converter is in fluid communication with the outlet of the decomposition furnace to receive a gas stream containing sulfur dioxide for conversion to sulfur trioxide.A conditioning vessel may be positioned between the decomposition furnace and the catalytic converter to receive the sulfur dioxide stream exiting the furnace in order to remove moisture and impurities from the stream. The inlet end of the conditioning vessel is in fluid communication with the outlet end of the decomposition furnace, while the outlet end of the conditioning vessel is in fluid communication with one end. Petition 870250108202, dated 11 / 26 / 2025, page 20 / 40 17 / 27 inlet of the catalytic converter. A sulfuric acid absorption vessel may be positioned downstream of the catalytic converter and in fluid communication with it. The inlet end of the sulfuric acid absorption vessel is in fluid communication with the outlet end of the catalytic converter for the purpose of receiving a gas stream containing sulfur trioxide.

[0040] Figure 1 shows a schematic representation of a known sulfuric acid regeneration plant 10. The sulfuric acid regeneration plant 10 includes a decomposition furnace 12, a feed conditioning chamber 14, a catalytic converter 30, an absorption tower 18 or vessel, and a collection chamber 20 for regenerated sulfuric acid. A spent sulfuric acid feed or other sulfur-containing feed 11 and an atmospheric air feed 13 are injected into the decomposition furnace 12. The conditioning chamber 14 is positioned between the decomposition furnace 12 and the catalytic converter 30 to receive the sulfur dioxide stream 15 exiting the furnace 12 to remove moisture and impurities from the stream 15. The conditioning chamber 14 may be optional and, when used, will also purify the sulfur dioxide stream 15.The catalytic converter 30 receives the conditioned sulfur dioxide stream 17 exiting the conditioning chamber 14, while a dry air stream 16 is also supplied to the catalytic converter 30. The absorption vessel 18 is positioned downstream of the catalytic converter 30. An inlet end of the absorption vessel 18 is in fluid communication with the outlet end of the catalytic converter 30 for the purpose of receiving a gas stream. Petition 870250108202, dated 11 / 26 / 2025, page 21 / 40 18 / 27 containing sulfur trioxide. The regenerated sulfuric acid is collected in collection chamber 20.

[0041] Figure 2 shows a schematic representation of a known multi-stage catalytic converter 30 for converting sulfur dioxide to sulfur trioxide. The catalytic converter 30 includes an elongated housing 31 having an upstream inlet end 32 and a downstream outlet end 33. A gas stream containing sulfur dioxide (17, Figure 1) is delivered to the catalytic converter 30 through pipe 34 which is in fluid communication with the inlet 32. The oxidizing atmospheric air stream (16, Figure 1) is delivered to the catalytic converter 30 through pipe 35 which is in fluid communication with the inlet 32. The catalytic converter 30 includes a plurality of catalytic regions or stages 36a-36d which include suitable catalyst for catalytically oxidizing at least a portion of the sulfur dioxide-containing feed delivered through pipe 34 to the catalytic converter.The catalytic converter 30 also includes a plurality of heat exchangers 37a-37c to remove thermal energy generated during the oxidation process of sulfur dioxide into sulfur trioxide. The catalytic converter 30 also includes a plurality of pipes 38a-38f to fluidly connect the plurality of catalytic regions 36a-36d and the plurality of heat exchangers 37a-37c. The gas stream containing sulfur trioxide exits the catalytic converter 30 at outlet 33 through pipe 39.

[0042] Figure 3 shows a schematic representation of an illustrative embodiment of the multi-stage catalytic converter presently disclosed 40 Petition 870250108202, dated 11 / 26 / 2025, page 22 / 40 19 / 27 to convert sulfur dioxide into sulfur trioxide. The catalytic converter 40 includes an elongated housing 41 which has an upstream inlet end 42 and a downstream outlet end 43. A gas stream containing sulfur dioxide is delivered to the catalytic converter 40 through pipe 44 which is in fluid communication with the inlet 42. An oxidizing atmospheric air stream is delivered through pipe 45 to pipe 44, wherein pipe 44 supplies the sulfur dioxide-containing stream to the catalytic converter 40. Pure oxygen is supplied through pipe 46 to the oxidizing atmospheric air in pipe 45. Consequently, downstream of where pipe 46 is in fluid communication with, or connected to, pipe 45, oxygen-enriched oxidizing air is supplied in a portion 45' of pipe 45.Alternatively, for the delivery of oxygen-enriched oxidizing air through pipe portion 45', a stream of pure oxygen may be supplied through pipe 47 to pipe 44. The result is that a portion of the atmospheric air in pipe 45 is replaced by oxygen delivered from pipes 46 and / or 47. The catalytic converter 40 includes a plurality of catalytic regions or stages 48a-48d which include suitable catalyst for catalytically oxidizing at least a portion of the sulfur dioxide-containing feed delivered to the catalytic converter through pipe 44. The catalytic converter 40 also includes a plurality of heat exchangers 49a-49c to remove thermal energy generated during the oxidation process of sulfur dioxide to sulfur trioxide. The catalytic converter 40 also includes a plurality of pipes 50a-50f to fluidly connect the plurality of catalytic regions 48a-48d and the plurality of heat exchangers 49a-49c.The gas stream that contains. Petition 870250108202, dated 11 / 26 / 2025, page 23 / 40 20 / 27 Sulfur trioxide exits the catalytic converter 40 at outlet 43 through pipe 51.

[0043] Figure 4 shows a schematic representation of another illustrative embodiment of the multi-stage catalytic converter presently disclosed 60 for converting sulfur dioxide into sulfur trioxide. The catalytic converter 60 includes an elongated housing 61 having an upstream inlet end 62 and a downstream outlet end 63. A gas stream containing sulfur dioxide is delivered to the catalytic converter 60 through pipe 64 which is in fluid communication with the inlet 62. An oxidizing atmospheric air stream is delivered through pipe 65 to pipe 64, wherein pipe 64 supplies the sulfur dioxide-containing stream to the catalytic converter 60. Pure oxygen is supplied through pipe 66 to the oxidizing atmospheric air in pipe 65. Consequently, downstream of where pipe 66 is in fluid communication with, or connected to, pipe 65, oxygen-enriched oxidizing air is supplied in a portion 65' of pipe 65.Alternatively, for the delivery of oxygen-enriched oxidizing air through pipe portion 65', a stream of pure oxygen may be supplied through pipe 67 to pipe 64. The result is that a portion of the atmospheric air in pipe 65 is replaced by oxygen delivered from pipes 66 and / or 67. The catalytic converter 60 includes a plurality of catalytic regions or stages 68a-68d which include suitable catalyst for catalytically oxidizing at least a portion of the sulfur dioxide-containing feed delivered to the catalytic converter through pipe 64. The catalytic converter 60 also includes a plurality of heat exchangers 69a-69c for removing generated thermal energy. Petition 870250108202, dated 11 / 26 / 2025, page 24 / 40 21 / 27 during the oxidation process of sulfur dioxide to sulfur trioxide. The catalytic converter 60 also includes a plurality of pipes 70a-70f to fluidly connect the plurality of catalytic regions 68a-68d and the plurality of heat exchangers 69a-69c. The catalytic converter 60 further includes a branch 66' or pipe extending from pipe 66, and in fluid communication with it. A plurality of pipes 71a-71c or inlets are in fluid communication with branch 66' and pipes 70b, 70d, 70f, respectively, through orifices 72a-72c, respectively, located in a side wall 73 of the catalytic converter 60. Oxygen-enriched atmospheric oxidizing air and / or pure oxygen is delivered to pipes 70b, 70d, 70f in the catalytic converter housing 61 through pipes 71a-71c extending along the side wall 73 downstream of each of the heat exchangers 69a-69c, respectively. The gas stream containing sulfur trioxide exits the catalytic converter 60 at outlet 63 through pipe 74.

[0044] Figure 5 shows a schematic representation of another illustrative embodiment of the presently disclosed multistage catalytic converter 80 for converting sulfur dioxide into sulfur trioxide. The catalytic converter 80 includes an elongated housing 81 having an upstream inlet end 82 and a downstream outlet end 83. A gas stream containing sulfur dioxide is delivered to the catalytic converter 80 through pipe 84 which is in fluid communication with the inlet 82. An oxygen-enriched oxidizing air stream is delivered through pipe 85 to pipe 84, wherein pipe 84 supplies the sulfur dioxide-containing stream to the catalytic converter. Petition 870250108202, dated 11 / 26 / 2025, page 25 / 40 22 / 27 80. Pure oxygen is supplied through pipe 86 to the oxidizing atmospheric air in pipe 85. Consequently, downstream of where pipe 86 is in fluid communication with, or connected to, pipe 85, oxygen-enriched oxidizing air is supplied in a portion 85' of pipe 85. Additionally or alternatively, for the delivery of oxygen-enriched oxidizing air through the portion of pipe 85', a stream of pure oxygen may be supplied through pipe 87 to pipe 84. The result is that a portion of the atmospheric air in pipe 85 is replaced by oxygen delivered from pipes 86 and / or 87. The catalytic converter 80 includes a plurality of catalytic regions or stages 88a-88d which include suitable catalyst for catalytically oxidizing at least a portion of the sulfur dioxide-containing feed delivered to the catalytic converter by pipe 84.The catalytic converter 80 also includes a plurality of heat exchangers 89a-89c for removing thermal energy generated during the oxidation process of sulfur dioxide into sulfur trioxide. The catalytic converter 80 also includes a plurality of pipes 90a-90f for fluidly connecting the plurality of catalytic regions 88a-88d and the plurality of heat exchangers 89a-89c. The catalytic converter 80 further includes a branch 86' or a pipe extending from pipe 86, and in fluid communication with it. A plurality of pipes 91a-91c or inlets are in fluid communication with branch 86' and pipes 90a, 90c, 90e, respectively, through orifices 92a-92c, respectively, located in a side wall 93 of the catalytic converter 80. Oxygen-enriched atmospheric oxidizing air and / or pure oxygen is delivered to pipes 90a, 90c, 90e in housing 81 of the catalytic converter. Petition 870250108202, dated 11 / 26 / 2025, page 26 / 40 23 / 27 through pipes 91a-91c that extend along the side wall 93 upstream of each of the heat exchangers 89a-89c. The gas stream containing sulfur trioxide exits the catalytic converter 80 at outlet 83 through pipe 94.

[0045] According to certain illustrative embodiments of the present invention, a process is provided for converting sulfur dioxide into sulfur trioxide that includes (a) introducing a sulfur dioxide feed stream into a catalytic converter to convert sulfur dioxide into sulfur trioxide; (b) introducing an oxygen-enriched feed stream, a pure oxygen feed stream, or both the oxygen-enriched feed stream and the pure oxygen feed stream into the catalytic converter; and (c) catalytically oxidizing at least a portion of the sulfur dioxide from the sulfur dioxide feed stream to produce sulfur trioxide.

[0046] Other embodiments of the process include (b) comprising adding the oxygen-enriched feed stream to the catalytic converter.

[0047] Other embodiments of the process include (b) comprising adding the pure oxygen feed stream to the catalytic converter.

[0048] Other embodiments of the process include (b) comprising adding both oxygen-enriched feed stream and pure oxygen feed stream to the catalytic converter.

[0049] Other forms of the process include oxygen-enriched feed stream comprising air. Petition 870250108202, dated 11 / 26 / 2025, page 27 / 40 24 / 27

[0050] Other embodiments of the process include the catalytic oxidation of at least a portion of the sulfur dioxide from the sulfur dioxide feed stream that occurs in at least one catalytic region within the catalytic converter.

[0051] Other embodiments of the process further comprise removing thermal energy from the sulfur dioxide feed stream with at least one heat exchanger operating in conjunction with the sulfur dioxide feed stream.

[0052] Other embodiments of the process further comprise catalytically oxidizing at least a portion of the sulfur dioxide from the sulfur dioxide feed stream in a plurality of catalytic regions within the catalytic converter and removing thermal energy from the sulfur dioxide feed stream with a plurality of heat exchangers operating in conjunction with the sulfur dioxide feed stream.

[0053] Other embodiments of the process include catalytically oxidizing at least a portion of the sulfur dioxide occurring in more than one catalytic region and more than one heat exchanger alternately positioned along the catalytic converter. Other embodiments of this process include (b) comprising introducing oxygen-enriched feed stream, pure oxygen feed stream, or both oxygen-enriched feed stream and pure oxygen feed stream into the catalytic converter at a position upstream of a first catalytic region of the catalytic converter. Other embodiments of this process include (b) comprising Petition 870250108202, dated 11 / 26 / 2025, page 28 / 40 25 / 27 introduction of oxygen-enriched feed stream, pure oxygen feed stream, or both oxygen-enriched and pure oxygen feed stream into the catalytic converter at a position upstream of one or more heat exchangers. Other embodiments of this process include (b) comprising introducing oxygen-enriched feed stream, pure oxygen feed stream, or both oxygen-enriched and pure oxygen feed stream into the catalytic converter at a position downstream of one or more heat exchangers.

[0054] Other embodiments of the process include a sulfur dioxide feed stream comprising at least one of a spent sulfuric acid stream or another sulfur-containing stream from a furnace.

[0055] According to certain illustrative embodiments in the present invention, an apparatus is provided for converting sulfur dioxide into sulfur trioxide, which includes a housing; an inlet to the housing for supplying a feed containing sulfur dioxide into the housing; at least one catalytic region positioned in the housing for converting sulfur dioxide into sulfur trioxide and at least one inlet for supplying a feed stream of oxygen-enriched combustion air or a feed stream of pure oxygen into the feed containing sulfur dioxide.

[0056] Other embodiments of the apparatus additionally comprise at least one heat exchanger in fluid communication with at least one catalytic region. Petition 870250108202, dated 11 / 26 / 2025, page 29 / 40 26 / 27

[0057] Other apparatus modalities include the inlet that is positioned upstream of a first catalytic region of the housing.

[0058] Other embodiments of the apparatus include another inlet that is positioned upstream of at least one heat exchanger.

[0059] Other embodiments of the apparatus include another inlet that is positioned downstream of at least one heat exchanger.

[0060] Other embodiments of the apparatus additionally comprise a decomposition furnace positioned upstream of the housing, wherein the decomposition furnace comprises an outlet to supply the feed containing sulfur dioxide from the decomposition furnace to the housing inlet.

[0061] Other embodiments of the apparatus additionally comprise a sulfuric acid absorption vessel positioned downstream of the housing to receive sulfur trioxide.

[0062] Other embodiments of the apparatus include at least one heat exchanger that is positioned inside the housing.

[0063] Other embodiments of the apparatus include at least one heat exchanger that is positioned outside the housing.

[0064] Other embodiments of the apparatus include a plurality of catalytic regions and a plurality of heat exchangers that are positioned within the housing in fluid communication with each other in a successive alternating arrangement.

[0065] Other device configurations include Petition 870250108202, dated 11 / 26 / 2025, pages 30 / 40 27 / 27 additionally at least one other inlet (71a-c) for the pure oxygen feed stream positioned downstream of at least one heat exchanger.

[0066] Other embodiments of the apparatus additionally comprise at least one other inlet (91a-c) for the pure oxygen supply stream positioned upstream of at least one heat exchanger.

[0067] It will be understood that the embodiments described in the present invention are merely illustrative and that a person skilled in the art may make variations and modifications without departing from the spirit and scope of the invention. All such variations and modifications are intended to be included within the scope of the invention provided in the appended claims. It should be understood that the embodiments described above are not only alternatives, but may be combined. Petition 870250108202, dated 11 / 26 / 2025, pp. 31 / 40

Claims

1 / 5 CLAIMS 1. Process for converting sulfur dioxide into sulfur trioxide, characterized by comprising: (a) introducing a sulfur dioxide feed stream into a catalytic converter to convert sulfur dioxide into sulfur trioxide; (b) introducing an oxygen-enriched feed stream, a pure oxygen feed stream, or both the oxygen-enriched feed stream and the pure oxygen feed stream into the catalytic converter; and (c) catalytically oxidizing at least a portion of the sulfur dioxide from the sulfur dioxide feed stream to produce sulfur trioxide.

2. Process according to claim 1, characterized by (b) comprising adding the oxygen-enriched feed stream to the catalytic converter.

3. Process according to claim 1, characterized by (b) comprising adding the pure oxygen feed stream to the catalytic converter.

4. Process according to claim 1, characterized by (b) comprising adding both oxygen-enriched feed stream and pure oxygen feed stream to the catalytic converter.

5. Process according to claim 1, characterized in that the oxygen-enriched feed stream comprises air.

6. Process, according to claim 1, characterized in that the catalytic oxidation of at least a portion of the sulfur dioxide from the feed stream of Petition 870250094995, of 10 / 17 / 2025, page 8 / 18 2 / 5 sulfur dioxide occurs in at least one catalytic region within the catalytic converter.

7. Process according to claim 1, characterized by further comprising the removal of thermal energy from the sulfur dioxide feed stream with at least one heat exchanger operating in conjunction with the sulfur dioxide feed stream.

8. Process according to claim 1, characterized by further comprising the catalytic oxidation of at least a portion of the sulfur dioxide from the sulfur dioxide feed stream in a plurality of catalytic regions within the catalytic converter, and removing thermal energy from the sulfur dioxide feed stream with a plurality of heat exchangers operating in conjunction with the sulfur dioxide feed stream.

9. Process according to claim 1, characterized in that the catalytic oxidation of at least a portion of the sulfur dioxide occurs in more than one catalytic region and more than one heat exchanger alternately positioned along the catalytic converter.

10. Process according to claim 9, characterized by (b) comprising introducing oxygen-enriched feed stream, pure oxygen feed stream, or both oxygen-enriched feed stream and pure oxygen feed stream into the catalytic converter at a position upstream of a first catalytic region of the catalytic converter. Petition 870250094995, dated 10 / 17 / 2025, p. 9 / 18 3 / 5 11. Process according to claim 9, characterized by (b) comprising introducing oxygen-enriched feed stream, pure oxygen feed stream or both oxygen-enriched feed stream and pure oxygen feed stream into the catalytic converter at a position upstream of one or more heat exchangers.

12. Process according to claim 9, characterized by (b) comprising introducing oxygen-enriched feed stream, pure oxygen feed stream or both oxygen-enriched feed stream and pure oxygen feed stream into the catalytic converter at a position downstream of one or more heat exchangers.

13. Process according to claim 1, characterized in that the sulfur dioxide feed stream comprises: at least one of a spent sulfuric acid stream or another stream containing sulfur from a furnace.

14. Apparatus for converting sulfur dioxide into sulfur trioxide characterized by comprising a housing; an inlet to the housing for supplying a feed containing sulfur dioxide in the housing; at least one catalytic region positioned in the housing for converting sulfur dioxide into sulfur trioxide; and at least one inlet for supplying a feed stream of oxygen-enriched combustion air or a feed stream of pure oxygen in the feed. Petition 870250094995, 10 / 17 / 2025, page 10 / 18 4 / 5 containing sulfur dioxide.

15. Apparatus, according to claim 14, characterized by further comprising at least one heat exchanger in fluid communication with at least one catalytic region.

16. Apparatus, according to claim 14, characterized in that the inlet is positioned upstream of a first catalytic region of the housing.

17. Apparatus, according to claim 15, characterized in that another inlet is positioned upstream of at least one heat exchanger.

18. Apparatus, according to claim 15, characterized in that another inlet is positioned downstream of at least one heat exchanger.

19. Apparatus, according to claim 14, characterized by further comprising a decomposition furnace positioned upstream of the housing, wherein the decomposition furnace comprises an outlet to supply the feed containing sulfur dioxide from the decomposition furnace to the housing inlet.

20. Apparatus, according to claim 14, characterized by further comprising a sulfuric acid absorption vessel positioned downstream of the housing to receive sulfur trioxide.

21. Apparatus, according to claim 15, characterized in that at least one heat exchanger is positioned inside the housing.

22. Apparatus, according to claim 15, characterized in that at least one heat exchanger is positioned externally to the housing. Petition 870250094995, dated 10 / 17 / 2025, page 11 / 18 5 / 5 23. Apparatus, according to claim 14, characterized by a plurality of catalytic regions and a plurality of heat exchangers being positioned within the housing in fluid communication with each other in a successive alternating arrangement.

24. Apparatus, according to claim 15, characterized by further comprising at least one other inlet (71a-c) for the pure oxygen feed stream positioned downstream of at least one heat exchanger.

25. Apparatus, according to claim 15, characterized by further comprising at least one other inlet (91a-c) for the pure oxygen feed stream positioned upstream of at least one heat exchanger. Petition 870250094995, dated 10 / 17 / 2025, p. 12 / 18

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