PROCESSO PARA DECOMPOR PELO MENOS UMA DENTRE UMA CORRENTE DE ÁCIDO SULFÚRICO GASTO OU OUTRA CORRENTE CONTENDO ENXOFRE

Description

1 / 35 PROCESS FOR DECOMPOSING AT LEAST ONE OF A STREAM OF SPENT SULFURIC ACID OR ANOTHER STREAM CONTAINING SULFUR FIELD OF TECHNIQUE

[0001] The present embodiments relate to a method and apparatus for regenerating a spent acid stream or a stream containing a precursor. Illustrative embodiments relate to a method and apparatus for preparing sulfur dioxide from a spent sulfuric acid stream or other sulfur-containing streams. BACKGROUND

[0002] Spent sulfuric acid streams and other sulfur-containing streams can be recovered in a single-stage spent acid decomposition furnace to produce sulfur dioxide, which in turn can be used for the purpose of producing pure sulfuric acid.

[0003] A single-stage spent acid decomposition furnace operating at full capacity is limited by a number of operational constraints, including the pressure drop across the furnace, the furnace outlet gas temperature, and the furnace NOx emissions.

[0004] Known processes have proposed adding supplemental oxygen to the combustion air to allow the oxidation of more spent sulfuric acid and other sulfur-containing compounds in the decomposition furnace, producing more sulfur dioxide, which is the raw material for preparing pure sulfuric acid.

[0005] The addition of supplemental oxygen to the decomposition furnace to oxidize larger quantities of compounds Petition 870250108701, dated 11 / 27 / 2025, page 6 / 54 2 / 35 containing sulfur reduces the nitrogen concentration in the furnace, making the flame more compact and causing the maximum flame temperature to increase, resulting in greater dissociation of nitrogen and oxygen and increases in hydroxyl radical concentrations, which leads to higher NOx emissions. The simple addition of oxygen to the combustion air will also increase the volumetric flow rate through the furnace, causing an unacceptable increase in the pressure drop in the furnace.

[0006] Therefore, there is a need in the technique to increase the furnace capacity to recover more spent acid and / or produce more sulfur dioxide without exceeding the operational constraints, and to overcome the disadvantages described above. SUMMARY

[0007] According to a first illustrative embodiment, a process is provided for decomposing at least one of a spent sulfuric acid stream or other sulfur-containing stream comprising: supplying at least one of the spent sulfuric acid stream or other sulfur-containing stream to a furnace; supplying oxygen-enriched combustion air to the furnace; supplying pure oxygen to the furnace; and oxidizing at least one of the spent sulfuric acid stream or other sulfur-containing stream in the furnace.

[0008] According to a second illustrative embodiment, an apparatus is provided for decomposing at least one of a spent sulfuric acid feed or a sulfur-containing feed comprising: a decomposition furnace; an inlet for supplying at least one of a spent sulfuric acid stream or a sulfur-containing stream to the decomposition furnace; an inlet for supplying an oxygen-enriched combustion air stream to Petition 870250108701, dated 11 / 27 / 2025, page 7 / 54 3 / 35 decomposition furnace; an inlet to supply a stream of pure oxygen to the decomposition furnace separately from the oxygen-enriched combustion air stream; and an inlet to supply a stream of combustion fuel to the decomposition furnace.

[0009] According to a third illustrative embodiment, a process is provided for preparing sulfuric acid from at least one of a decomposed spent sulfuric acid stream or another sulfur-containing stream comprising: supplying at least one of the spent sulfuric acid stream or the other sulfur-containing stream to a furnace; supplying oxygen-enriched combustion air to the furnace; separately supplying pure oxygen to the furnace; oxidizing at least one of the spent sulfuric acid stream or another sulfur-containing stream in the furnace to sulfur dioxide; and converting the sulfur dioxide to sulfuric acid. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] For a more complete understanding of the present embodiments, reference may be made to the following description of exemplary embodiments considered in connection with the attached drawing figure, of which:

[0011] The figure is a schematic view of the actual process and apparatus modalities for decomposing a spent sulfuric acid stream or another sulfur-containing stream. DETAILED DESCRIPTION OF THE ILLUSTRATIVE MODALITIES

[0012] Before explaining the inventive embodiments in detail, it should be understood that the invention is not limited in its application to the construction details and arrangement of parts illustrated in the accompanying drawings, if any, since the Petition 870250108701, dated 11 / 27 / 2025, page 8 / 54 4 / 35 The invention is capable of other embodiments and can be practiced or carried out in various ways. Furthermore, it should be understood that the phraseology or terminology employed herein is for descriptive purposes only and not for limitation.

[0013] In the following description, terms such as horizontal, vertical, above, below, underneath and the like, should be used only for the purpose of clarity in illustrating the invention and should not be taken as limiting words. The drawings are intended to illustrate the invention and are not to be to scale.

[0014] A process is disclosed for decomposing a spent acid stream or other stream containing an acid precursor. The process comprises supplying at least one spent acid stream or other acid precursor stream to a furnace suitable for oxidizing the spent acid stream or other feed containing an acid precursor. The process comprises supplying an oxygen-enriched combustion air stream to the furnace and separately supplying a pure oxygen stream to the furnace. The process further comprises oxidizing at least a portion of the spent acid stream or other acid precursor stream supplied to the furnace.

[0015] According to certain illustrative embodiments, the process is directed to decompose a spent sulfuric acid stream and / or a sulfur-containing stream. The processes disclosed herein increase the production capacity of a decomposition furnace to produce sulfur dioxide from at least one of the spent sulfuric acid stream or another sulfur-containing stream, without increasing the pressure drop within the furnace, the volumetric flow rate of the decomposition furnace, the Petition 870250108701, dated 11 / 27 / 2025, page 9 / 54 5 / 35 temperature of the gas exiting the decomposition furnace and / or the NOx emissions from the decomposition furnace.

[0016] The process comprises supplying at least one of a spent sulfuric acid stream or other sulfur-containing stream to a suitable decomposition furnace for oxidizing the spent sulfuric acid stream and / or other sulfur-containing stream to sulfur dioxide. The other sulfur-containing streams that may be used in the process may comprise, for example, and without limitation, an elemental sulfur stream, a stream of a sulfur-containing compound, or a sulfur-containing refinery acid gas. The process comprises supplying an oxygen-enriched combustion air stream to the furnace and separately supplying a pure oxygen stream to the furnace. The process further comprises oxidizing at least a portion of the spent sulfuric acid stream supplied to the furnace to sulfur dioxide.

[0017] According to other illustrative embodiments, the process is directed to decompose a sulfur-containing stream, other than a spent sulfuric acid stream. The process comprises supplying the sulfur-containing stream to a suitable furnace for oxidizing the sulfur-containing stream. The process comprises supplying an oxygen-enriched combustion air stream to the furnace and separately supplying a pure oxygen stream to the furnace. The process further comprises oxidizing at least a portion of the sulfur-containing stream supplied to the furnace.

[0018] The combustion air stream accounts for a significant fraction of the mass entering the furnace and is the primary source of nitrogen that is oxidized to form thermal NOx. Because combustion air is composed primarily of Petition 870250108701, dated 11 / 27 / 2025, page 10 / 54 6 / 35 nitrogen, it is possible to replace part of the ambient air with pure oxygen, so that the process requires less total mass of oxygen and combustion air to achieve complete combustion in the furnace. Replacing a sufficient mass of combustion air with oxygen results in an increase in the furnace's ability to oxidize sulfur-containing compounds without increasing the total mass flow rate.

[0019] According to certain embodiments, the disclosed process provides first and second oxygen enrichments to a furnace. According to the disclosed process, the first oxygen enrichment comprises replacing a portion of the combustion air with oxygen to provide at least one oxygen-enriched combustion air stream that is supplied to the decomposition furnace. The second oxygen enrichment comprises at least one pure oxygen stream that is supplied to the furnace separately from at least one oxygen-enriched combustion air stream. According to certain embodiments, the disclosed process may divide the overall oxygen enrichment into separate parts, such that at least one portion of the second oxygen enrichment is injected directly into the decomposition furnace at the periphery of the primary flame zone.

[0020] According to certain embodiments, the disclosed process can reduce the combustion airflow, the combustion air is not intensified with oxygen, and all supplemental oxygen enrichment is injected directly into the furnace. This creates a larger and cooler primary flame zone that allows more air to be replaced by pure oxygen, resulting in the furnace's ability to oxidize a greater amount of sulfur-containing compounds without increasing the Petition 870250108701, dated 11 / 27 / 2025, page 11 / 54 7 / 35 pressure drop, furnace outlet gas temperature or NOx emissions.

[0021] Although preheated combustion air is normally supplied to the furnace burners and provides a relatively discreet means of introducing oxygen into the furnace, the present inventors have learned that it is not the ideal location to introduce all the oxygen. The adiabatic flame temperature of an oxygen-enhanced flame is higher than that of combustion with air, and therefore introducing all the oxygen-enriched combustion air through the burners will result in a primary flame zone that is hotter than before. This would result in increased rates of thermal formation of NOx and potentially a higher furnace exhaust gas temperature.

[0022] According to certain illustrative embodiments of the currently disclosed process, at least a portion of the oxygen supplied to the furnace is distributed or otherwise directed to the edges of the primary flame zone to allow the oxidation of sulfur-containing compounds to occur in a larger flame zone with a more uniform temperature profile. According to the currently disclosed process, the directed supply of oxygen reduces the volume of the flame zone that occurs at maximum flame temperatures and the rate at which thermal NOx is formed and emitted from the furnace.

[0023] Not all oxygen needs to be supplied to the furnace through the burners, and excessive oxygen concentrations can lead to locally elevated temperatures. According to certain illustrative embodiments, the process controls the division of oxygen between the overall oxygen enrichment in the combustion air stream that is delivered to the Petition 870250108701, dated 11 / 27 / 2025, page 12 / 54 8 / 35 furnace burners, and targeted oxygen enrichment comprising the injection of pure oxygen into or near the periphery of the primary flame to control combustion and process conditions. The process step of supplying at least a portion of the targeted oxygen to the edges or periphery of the primary flame zone within the furnace allows for a higher oxygen concentration spread over a larger volume than could be achieved by supplying combustion air to the burners alone, thus resulting in a flame zone that occupies a larger volume with a lower maximum temperature.

[0024] The apparatus and process provide two separate oxygen feeds to the furnace at distinct injection locations. One of the two oxygen feeds is supplied to the furnace (this may be referred to as the robust oxygen injector), and the other of the two oxygen feeds is introduced into a duct or pipe carrying combustion air to the furnace (this may be referred to as the diffused oxygen injector) to mix with the combustion air and provide oxygen-enriched combustion air. According to certain embodiments, this oxygen feed may be supplied to an inlet or outlet duct of the combustion air preheater in order to mix the oxygen enrichment with the combustion air.

[0025] According to certain embodiments, the initial target of how the total additional oxygen supplied is divided between the oxygen-enriched combustion air and the targeted enrichment is to supply only the oxygen necessary in the oxygen-enriched combustion air to maintain the adiabatic flame temperature and / or the ratio Petition 870250108701, dated 11 / 27 / 2025, page 13 / 54 9 / 35 stoichiometric burner.

[0026] The total oxygen flow to the apparatus is determined to provide the necessary available heat and chemical reaction in the apparatus through a balance of mass and energy, while keeping the volume of combustion products below a maximum value determined by the maximum pressure drop across the system.

[0027] The process provides a controlled supply of oxygen to the decomposition furnace between the overall oxygen enrichment of the combustion air supply from the burners operating in the decomposition furnace and the direct injection of oxygen into the decomposition furnace. The total oxygen flow to the system is determined to limit the combustion gas volumes while maintaining the oxygen concentrations and temperatures of the exhaust gases for varying feed stream flows and compositions.

[0028] Without replacing part of the combustion air by using supplemental oxygen enrichment at higher feed rates, the volumetric flow rate of combustion gas increases and the residence time in the furnace available for reactions is reduced due to the following mechanisms: • Increased volume of sulfur and acid decomposition products; and • Higher fuel flows and, therefore, higher air and combustion product flows to maintain furnace exhaust temperatures. This leads to the following effects: • Higher loads on the combustion gas system. For example, the induced draft fan, which Petition 870250108701, dated 11 / 27 / 2025, page 14 / 54 10 / 35 draws air and combustion products through the decomposition furnace while maintaining negative pressure in the furnace; this is generally a limit. • The higher quantity of combustion air is required, obtained from the suction of the induced draft fan along with the forced draft fans blowing air onto the burners. • Increased speed through the system and reduced residence time for reactions can lead to poor decomposition.

[0029] Oxygen supplementation can alleviate or improve these effects. Decomposition furnaces can be stoichiometrically driven by flue gas oxygen measurements. By supplementing the flue air with oxygen, the flue air flow is consequently reduced by the production plant automation system to maintain the desired residual flue gas oxygen concentration. This results in a reduced amount of ballast nitrogen in the combustion oxidizer (mixture of flue air and oxygen) and flue gas (reducing the load on the induced and forced draft fans) and an increased residence time at a fixed acid feed rate.

[0030] It is known that enriching the combustion air with oxygen at a constant stoichiometry raises the temperatures of the flame and combustion products, which has an adverse effect on NOx formation and can be detrimental to the service life of the furnace refractory. For these reasons, the currently disclosed process supplies at least part of the oxygen through pure oxygen injectors directly into the furnace. Petition 870250108701, dated 11 / 27 / 2025, page 15 / 54 11 / 35 decomposition, directed close to the flames emanating from the burners, with the oxygen balance as a stream of oxygen-enriched combustion air to enhance combustion. As some of the total oxygen supplied is not introduced through the enriched combustion air and the amount of air has been reduced to maintain the overall oxygen concentration in the furnace exhaust, the stoichiometry of the burners and flame will fall or be reduced. As the stoichiometric condition is reached and exceeded, this has the effect of increasing and then reducing the flame temperature and the concentrations of radicals (i.e., O, N, and OH) important in NOx formation.

[0031] The directly injected oxygen stream (or streams) is introduced into the decomposition furnace through at least one high-velocity nozzle, preferably sonic, to produce high-velocity oxygen jets close to the burner flames, spent sulfuric acid, and sulfur jets. The high-velocity oxygen jets carry and mix with the hot furnace atmosphere containing reacted and partially unreacted fuels and cause their diffuse oxidation. Such diffuse oxidation reactions avoid the maximum flame temperatures observed in conventional combustion that drive NOx formation and distribute the overall reactions over a larger region than in the confluence zone of the main burners.Therefore, it is desirable to be able to control the splitting or separation of oxygen from the general enrichment of the combustion air to that of direct oxygen injection, in order to control combustion and related process conditions.

[0032] According to certain modalities Petition 870250108701, dated 11 / 27 / 2025, page 16 / 54 12 / 35 illustrative, the oxygen enrichment supplied to the decomposition furnace is provided only by one or more oxygen streams that are supplied to the furnace separately from the combustion air stream, and the combustion air stream is not enriched with oxygen. Consequently, this embodiment provides a process for regenerating a spent sulfuric acid stream or other sulfur-containing stream comprising: supplying at least one of the spent sulfuric acid stream or other sulfur-containing stream to a furnace, supplying combustion air to the furnace, supplying pure oxygen to the furnace separately from the combustion air, and oxidizing at least one of the spent sulfuric acid stream or other sulfur-containing stream in the furnace.

[0033] The apparatus includes a controller to control a plurality of oxygen flows (two flows, for example) to at least two separate locations: at least one general enrichment stream for at least one burner and at least one injection stream for direct injection into the furnace. A controller flow train provides basic safety functions, including automatic oxygen shut-off valves activated by excessive process deviations such as pressures, flows, temperatures, process interlocks, and emergency stops. To modulate and measure the flows, the flow train also includes inlet pressure regulation, flow meters, and flow control valves connected to the controller.

[0034] A TS temperature sensing element, such as a thermocouple or a pyrometer, is preferably located in the front region of the decomposition furnace, approximately aligned with a zone that accommodates the flames. Petition 870250108701, dated 11 / 27 / 2025, p. 17 / 54 13 / 35 produced by the burners. This temperature is representative of excessively low or high temperatures experienced within the flame zone. A temperature setpoint within a temperature range is determined by previous satisfactory operation. The proportion of total oxygen supplied to the system and distributed throughout the overall enrichment system responds to deviation from a desired temperature setpoint; that is, if the TS temperature is too low, then the proportion of oxygen supplied to the enriched air is increased; if the TS temperature is too high, then the proportion of oxygen supplied to the enriched air is reduced.In this design and operation, during instances of changes in productivity, or changes in the composition of the feed streams, the split of oxygen supplied by direct injection and the overall enrichment of the combustion air will be modulated to maintain the desired operating temperature window and reduce NOx emissions.

[0035] Pressure transmitters can be positioned immediately upstream of each oxygen injector, sprayer, or diffuser used for general combustion air enrichment and injectors for direct oxygen injection. The outputs of the pressure transmitters are continuously monitored along with the flow rate to determine any deviation from intended and historical values ​​that indicate a blockage, wear, or failure in the enrichment or injection system.

[0036] The controller is in communication with the oxygen flow control of the flow train and the TS temperature sensor. The controller or control routine is in Petition 870250108701, dated 11 / 27 / 2025, page 18 / 54 14 / 35 Communication with the TS temperature sensor, flow meters, and oxygen flow train control valves. The controller maintains the total oxygen flow at the desired oxygen flow setpoint and determines the actual flows for each location (at least one for general enrichment and at least one for direct injection) based on the temperature deviation between the temperature indicated by the TS and the desired combustion zone setpoint temperature. As the temperature at the TS falls below the setpoint temperature, the controller instructs the oxygen flow train control valves to supply a higher oxygen flow to the general enrichment diffuser or sprayer and less to the direct oxygen injector, thus maintaining a constant total oxygen flow at the desired setpoint for total oxygen flow.On the other hand, if the temperature in TS rises above the setpoint temperature range, the controller instructs the oxygen flow train control valves to supply a lower oxygen flow to the general enrichment diffuser or sprayer and a higher oxygen flow to the direct oxygen injector, thus maintaining a constant total oxygen flow at the desired total oxygen flow setpoint. According to certain embodiments, a dead range or dead zone is an interval in which the controller takes no action; that is, the controller only makes a change when the temperature falls just outside the dead zone around the desired setpoint in the control, in order to avoid frequent flow changes for only small temperature deviations. Such control functions are readily achievable with well-known industrial controllers, such as programmable logic controllers (PLCs). Petition 870250108701, dated 11 / 27 / 2025, page 19 / 54 15 / 35 Distributed control systems (DCS) or microprocessor-based controls that incorporate functions such as proportional-integral-derivative (PID) loop, on-off and deadband functions.

[0037] According to certain embodiments, an oxygen analyzer may be located at the furnace outlet to maintain a target level of excess oxygen in the exhaust, and the total oxygen flow to the apparatus is adjusted to maintain the target.

[0038] A stream of spent acid is supplied to the furnace through an inlet formed in the furnace wall that is in fluid communication with a conduit that carries the spent acid stream.

[0039] According to certain illustrative embodiments, at least one of the spent acid stream, the oxygen-enriched combustion air stream, or the pure oxygen stream may be preheated before introducing the stream into the decomposition furnace. Preheating of one or more of the spent acid stream, the oxygen-enriched combustion air stream, or the pure oxygen stream may be accomplished by indirectly heating the conduit (or conduits) or pipe (or pipes) that supplies one or more streams to the decomposition furnace. According to certain illustrative embodiments, none of the spent acid stream, the oxygen-enriched combustion air stream, or the pure oxygen stream is preheated before being supplied into the decomposition furnace.

[0040] According to other illustrative embodiments, the spent acid stream can be preheated Petition 870250108701, dated 11 / 27 / 2025, page 20 / 54 16 / 35 before introducing the spent acid stream into the decomposition furnace. For example, and without limitation, the spent acid stream may be heated indirectly by a suitable heater before introducing the stream into the furnace while that stream is being supplied through a suitable conduit.

[0041] According to other illustrative embodiments, the oxygen-enriched combustion air stream can be preheated before introducing the oxygen-enriched combustion air stream into the decomposition furnace. For example, and without limitation, the oxygen-enriched combustion air stream can be heated indirectly by a suitable heater before introducing the stream into the furnace while that stream is being supplied through a suitable duct. According to other illustrative embodiments, oxygen enrichment can be added to the combustion air after the combustion air has been preheated, thus resulting in a preheated oxygen-enriched combustion air stream.

[0042] According to other illustrative embodiments, the pure oxygen stream can be preheated before introducing the pure oxygen stream into the decomposition furnace. For example, and without limitation, the pure oxygen stream can be heated indirectly by a suitable heater before introducing the stream into the furnace while that stream is being supplied through a suitable conduit.

[0043] According to certain illustrative embodiments, the temperature of the oxygen-enriched combustion air stream supplied to the decomposition furnace is preheated to a temperature of about 20 °C to about 750 °C, or from about 400 °C to about 750 °C, Petition 870250108701, dated 11 / 27 / 2025, p. 21 / 54 17 / 35 or from about 600 to about 700 °C.

[0044] According to certain illustrative embodiments, the temperature of the gas exiting the decomposition furnace is from about 900 °C to about 1200 °C, or from about 960 °C to about 1100 °C, or from about 1000 °C to about 1060 °C.

[0045] According to certain illustrative embodiments, the percentage of oxygen present in the oxygen-enriched combustion air stream supplied to the decomposition furnace is from about 20.9% to about 30% (percentage by volume or v / v), or from about 20.9% to about 26% v / v, or from about 20.9% to about 23.5% v / v.

[0046] According to certain illustrative embodiments, the residence time of the spent acid stream in the decomposition furnace is from about 1.0 second to about 4.0 seconds, or from about 1.5 seconds to about 3.0 seconds, or from about 1.75 seconds to about 2.5 seconds.

[0047] According to certain illustrative embodiments, the total percentage of oxygen distributed to the furnace by the combination of the oxygen-enriched combustion air stream and the pure oxygen stream (or pure oxygen streams) is from about 21% to about 40% v / v, or from about 25% to about 35% v / v, or from about 28% to about 32% v / v.

[0048] According to certain illustrative embodiments, the percentage of oxygen present in the furnace exhaust stream is from about 0.5% to about 4% v / v, or from about 1.0% to about 2.5% v / v, or from about 1.5% to about 2.2% v / v.

[0049] The device for regenerating a food supply of Petition 870250108701, dated 11 / 27 / 2025, p. 22 / 54 18 / 35 spent acid or other feed containing acid precursor comprises a decomposition furnace having an outer housing with an interior having an internal volume. The housing includes a plurality of inlets to feed the various gas streams required by the regeneration process inside the furnace. The apparatus includes at least one inlet to supply each of combustion fuel, oxygen-enriched combustion air, pure oxygen, spent sulfuric acid stream, elemental sulfur stream or other sulfur-containing stream into the furnace. The apparatus includes separate inlets to separately supply or otherwise supply oxygen-enriched combustion air and pure oxygen into the furnace.

[0050] The apparatus further comprises a spent acid supply. The spent acid stream source is in fluid communication with the interior of the furnace. The apparatus includes an inlet for supplying spent acid to the decomposition furnace. A suitable heater may be positioned at any point between the spent acid source and the spent acid stream inlet of the furnace to preheat the spent acid stream before it is fed into the furnace.

[0051] The apparatus further comprises a source or supply of oxygen for use in the process. According to certain embodiments, the oxygen supply source may be divided or otherwise separated to separately supply a portion of pure oxygen directly into the furnace and to supply pure oxygen to the combustion air to prepare oxygen-enriched combustion air that is supplied into the furnace. Petition 870250108701, dated 11 / 27 / 2025, page 23 / 54 19 / 35

[0052] According to certain embodiments, the apparatus includes a suitable conduit or piping extending directly between, and in fluid communication with, the oxygen source or supply and the interior of the furnace to supply a stream of oxygen gas directly into the interior of the furnace, independently of the supply of oxygen-enriched combustion gas. The apparatus includes at least one inlet to supply a pure oxygen feed to the decomposition furnace separately from the supply of oxygen-enriched combustion air. A suitable heater may be positioned at any point between the oxygen source and the furnace oxygen gas inlet to preheat the oxygen gas before it is supplied into the interior of the furnace.

[0053] The apparatus further comprises a combustion air supply. The combustion air is supplied from the supply to the interior of the furnace by means of suitable ducts or pipes that are in fluid communication between the combustion air supply and the interior of the furnace. The apparatus includes at least one inlet for supplying a supply of oxygen-enriched combustion air to the decomposition furnace.

[0054] The apparatus also includes an oxygen supply that is in fluid communication with the ducts or pipes that carry the combustion air from the combustion air supply to the interior of the furnace. According to certain embodiments, oxygen is supplied from an oxygen source or supply directly into the duct or pipe that carries the combustion air from the combustion air source to the furnace, in order to prepare oxygen-enriched combustion air. Petition 870250108701, dated 11 / 27 / 2025, page 24 / 54 20 / 35

[0055] According to other embodiments, the apparatus includes a heater for preheating the combustion air within the duct or piping that carries the combustion air from the combustion air supply to the furnace. According to these embodiments, pure oxygen may be carried in suitable ducts or piping that are in fluid communication between the oxygen source and the heater to preheat the combustion air. In this case, pure oxygen may be supplied directly to the heater for the combustion air, where the oxygen is combined with the combustion air to prepare a heated oxygen-enriched combustion air that is then supplied to the furnace. According to other embodiments, the oxygen enrichment may be supplied from the oxygen source in ducts or piping that carry the combustion air at a location that is upstream or downstream of the combustion air heater.

[0056] The apparatus includes an adequate supply of combustion fuel. The combustion fuel is supplied from the fuel supply to the interior of the furnace by means of suitable ducts or pipes that are in fluid communication between the fuel supply and the interior of the furnace.

[0057] The combustion fuel feed may comprise a gaseous fuel selected from at least one of methane, natural gas, liquefied natural gas, propane, liquefied propane gas, butane, low BTU gases, town gas, producer gas, refinery fuel gas, hydrogen, carbon monoxide, and mixtures thereof. According to other embodiments, the combustion fuel feed may comprise an atomized liquid fuel. Petition 870250108701, dated 11 / 27 / 2025, page 25 / 54 21 / 35 selected from at least one of heavy fuel oil, medium fuel oil, light fuel oil, kerosene, diesel, and mixtures thereof. According to further embodiments, the combustion fuel feed may comprise a particulate solid fuel selected from at least one of coal, coke, petroleum coke, rubber, wood chips, sawdust, straw, biomass fuels, and mixtures thereof suspended in a carrier gas stream distributed in the furnace. The carrier gas stream may be selected from at least one of air, nitrogen, carbon dioxide, and a gaseous fuel, the gaseous fuel being selected from at least one of methane, natural gas, liquefied natural gas, propane, liquefied propane gas, butane, low BTU gases, town gas, producer gas, hydrogen, carbon monoxide, and mixtures thereof.

[0058] The Figure is a diagrammatic view of an illustrative embodiment of the apparatus of the present disclosure. The apparatus 10 includes a decomposition furnace 12 having an outer housing 14 and an inner housing 16. The housing 14 of the furnace 12 includes an inlet side 18 and an outlet side 20. The inlet side 18 of the housing 14 of the furnace 12 includes a plurality of inlets leading to the interior 16 of the furnace 12, as described below, to feed combustion fuel, spent acid streams, oxygen-enriched combustion air and pure oxygen into the interior 16 of the furnace 12.

[0059] Apparatus 10 includes a combustion fuel source 22. Suitable piping 24 extends between the combustion fuel source 22 and the interior 16 of furnace 12. Piping 24 is in fluid communication between the source of Petition 870250108701, dated 11 / 27 / 2025, p. 26 / 54 22 / 35 combustion fuel 22 and combustion fuel inlet 26 leading to furnace interior 16 to supply combustion fuel to furnace interior 16.

[0060] Apparatus 10 includes an air source 28 for combustion, that is, combustion air 28. Suitable piping 30 extends between the combustion air source 28 and the interior 16 of furnace 12. The piping 30 is in fluid communication between the combustion air source 28 and the combustion air inlet 32 ​​which leads to the interior 16 of furnace 12 to supply combustion air to the interior 16 of furnace 12.

[0061] Apparatus 10 includes a spent acid source 34 such as a spent sulfuric acid stream, refinery acid gas and / or a sulfur stream. Suitable piping 36 extends between the spent sulfuric acid source 34 and the interior 16 of furnace 12. The piping 36 is in fluid communication between the spent sulfuric acid source 34 and a corresponding spent sulfuric acid inlet 38 leading to the interior 16 of furnace 12 to supply spent sulfuric acid to the interior 16 of furnace 12.

[0062] Apparatus 10 also includes an oxygen gas source or supply 40 that provides oxygen to the combustion air 28 to prepare oxygen-enriched combustion air 31, and to provide a separate supply of pure oxygen to the furnace 12 as described below. A first oxygen flow control means 42 (such as an oxygen flow skid 1) is positioned between, and in fluid communication with, the oxygen source 40 and the piping 30 that carries the combustion air 28 into the interior 16 of the furnace 12. Apparatus 10 may also include an oxygen diffuser means 44 in fluid communication with the first means of Petition 870250108701, dated 11 / 27 / 2025, page 27 / 54 23 / 35 oxygen flow control 42 and the pipe 30 that carries the combustion air 28. Oxygen gas 40 is supplied via pipe 46 to the oxygen flow control medium 42 and from the first flow control medium 42 to the oxygen diffuser 44 or combustion air pipe 28. The first flow control medium 42 and the oxygen diffuser 44 ensure that the desired quantity of oxygen is injected into the combustion air 28 to prepare oxygen-enriched combustion air 31.

[0063] Apparatus 10 additionally includes a second oxygen flow control means 50 (such as an oxygen flow skid 2) positioned between, and in fluid communication with, the oxygen source 40 and one or a plurality of oxygen injectors 56 that carry pure oxygen 40 into the interior 16 of the furnace 12. Oxygen gas 40 is fed through piping 52 to the second oxygen flow control means 50 and from the flow control means 50 to one or a plurality of oxygen injectors 56 through piping 54. The second flow control means 50 ensures that the desired quantity of oxygen is injected into the interior 16 of the furnace housing 14.

[0064] Still referring to the Figure, the apparatus 10 includes O2 sensors 62, 68, each of which detects a quantity of O2 in a corresponding line 30 downstream of the O2 diffuser 44 and an outlet side 20 of the housing 14, respectively. Each of the O2 sensors 62, 68 generates a corresponding signal that is interpreted to understand if the quantity of O2 present in a line is within the correct range. For example, the O2 sensor 62 is in communication with line 30 downstream of an outlet of the O2 diffuser 44 to detect that the combustion air Petition 870250108701, dated 11 / 27 / 2025, p. 28 / 54 24 / 35 in line 30 has been sufficiently and correctly enriched with oxygen so that the now oxygen-enriched combustion air can be used in the combustion air inlet 32. The O2 sensor 62 generates a signal 64 and transmits the signal along a line 66, wirelessly or otherwise, to the O2 flow skid 42 to increase, decrease, or maintain the O2 flow to the O2 diffuser 44. Typically, there is a limit to the maximum allowable oxygen concentration in line 30 or in the combustion air inlet 32, determined by local operating codes and practices, the compatibility of construction materials with oxygen-enriched air, and / or the performance of the combustion equipment connected to the combustion air inlet 32. As such, there is a preferred limit to the O2 concentration in the oxygen-enriched air 31 in line 30 downstream of the outlet of the O2 diffuser 44.By way of example only, and not as a limitation, the amount of O2 in line 30 downstream of O2 diffuser 44 is preferably adjusted not to exceed 23.5%. In conjunction with this, the O2 sensor 68 on the outlet side 20 of the housing 14 detects a quantity of O2 that is present on the outlet side 20 and that will be supplied to the plant 60. The sensor 68 generates a signal 70 and transmits the signal along a line 72, wirelessly or otherwise, to the O2 supply 40. If the signal 70 includes a percentage of O2 outside an acceptable range of, for example, O2 2%-23.5% by volume, the O2 flow skids 42 and 50 will be activated to increase or decrease the O2 demand from the O2 supply 40. The O2 flow skid 42, in conjunction with the O2 sensor 62 and the signal 64, controls and limits the amount of O2 supplied to the O2 diffuser 44 such that the concentration of O2 in the oxygen-enriched air 31. Petition 870250108701, dated 11 / 27 / 2025, page 29 / 54 25 / 35 remain at a preferred value below the permitted limit. Any O2 demanded from the O2 supply 40 by the O2 sensor signal 70 68 in excess of that distributed by the O2 flow skid 42 in oxygen-enriched air 31 is supplied from the O2 flow skid 50 through line 54 to one or more O2 injectors 56.

[0065] The exhaust gas exiting from outlet side 20 of furnace 12 is fed to a collection vessel 60 and collected for conversion of the sulfur dioxide in the exhaust gas into sulfuric acid. The collected exhaust gas is fed to a suitable converter to convert the sulfur dioxide in the gas into sulfur trioxide and ultimately produce sulfuric acid.

[0066] According to the disclosed embodiments of the process and apparatus, the controlled oxygen supply is divided between a general oxygen enrichment in the combustion air supply and a separate oxygen enrichment by directed injection at or near the periphery of the primary flame of one or more furnace burners.

[0067] According to the disclosed embodiments of the process and apparatus, the ability to oxidize sulfur-containing compounds from a stream in a single-stage spent acid recovery furnace is increased.

[0068] According to the disclosed embodiments of the process and apparatus, the mass of combustion air that is introduced into the furnace is reduced by compensating part of the combustion air with pure oxygen that is either mixed with the remaining combustion air or injected directly into the furnace.

[0069] According to the disclosed embodiments of the process and apparatus, the furnace's ability to recover sulfur dioxide from a spent sulfuric acid stream or Petition 870250108701, dated 11 / 27 / 2025, page 30 / 54 26 / 35 Another feed stream containing a sulfur-containing compound is augmented by injecting directed oxygen into, near, or on the periphery of the primary flame of one or more furnace burners.

[0070] The disclosed embodiments of the process and apparatus provide the ability to control the local combustion conditions within the furnace by controlling the oxygen split between oxygen directed directly around the periphery of the primary flame and the general oxygen enrichment of the oxygen-enriched combustion air.

[0071] The disclosed embodiments of the process and apparatus provide the ability to control local combustion conditions within the furnace by controlling the oxygen split between oxygen directed directly around the periphery of the primary flame and the general oxygen enrichment of the oxygen-enriched combustion air, which avoids localized overheating as well as cooler or fuel-rich zones in which some of the sulfur dioxide could be reduced to elemental sulfur.

[0072] According to the disclosed embodiments of the process and apparatus, the production of sulfur dioxide is increased without increasing NOx emissions from the furnace or the pressure drop across the furnace.

[0073] Illustrative embodiments of the process for regenerating a spent acid stream or other acid precursor-containing stream of the present disclosure include:

[0074] According to a first illustrative embodiment, a process is provided for decomposing at least one of a spent sulfuric acid stream or other sulfur-containing stream comprising: providing at least Petition 870250108701, dated 11 / 27 / 2025, page 31 / 54 27 / 35 one of the spent acid streams or the other sulfur-containing stream to a furnace; supply oxygen-enriched combustion air to the furnace; supply pure oxygen to the furnace; and oxidize at least one spent sulfuric acid stream or other sulfur-containing stream in the furnace.

[0075] According to a second illustrative embodiment of the process for decomposing a spent sulfuric acid stream or another sulfur-containing stream, the process of the first illustrative embodiment is provided, in which the process further comprises the introduction of a combustion fuel into the furnace.

[0076] According to a third illustrative embodiment of the process for decomposing a spent sulfuric acid stream or other sulfur-containing stream, the process of the first or second illustrative embodiment is provided, which comprises decomposing a spent sulfuric acid stream.

[0077] According to a fourth illustrative embodiment of the process for decomposing a spent sulfuric acid stream or other sulfur-containing stream, the process of the first or second illustrative embodiment is provided, which comprises decomposing a sulfur-containing stream.

[0078] According to a fifth illustrative embodiment of the process for decomposing a spent sulfuric acid stream or other sulfur-containing stream, the process is provided for any one of the first through fourth illustrative embodiments, in which the step of supplying pure oxygen to the furnace comprises injecting pure oxygen into or near the periphery of the primary flame of one or more furnace burners.

[0079] According to a sixth modality Petition 870250108701, dated 11 / 27 / 2025, page 32 / 54 Figure 28 / 35 illustrates the process for decomposing a spent sulfuric acid stream or another sulfur-containing stream; the process is provided for any one of the first through fifth illustrative embodiments, in which the oxygen-enriched combustion air is heated before the oxygen-enriched combustion air is supplied to the furnace.

[0080] According to a seventh illustrative embodiment of the process for decomposing a spent sulfuric acid stream or other sulfur-containing stream, the process is provided for any one of the first through sixth illustrative embodiments, wherein, before the step of supplying oxygen-enriched combustion air to the furnace, oxygen is injected into the combustion air to prepare the oxygen-enriched combustion air.

[0081] According to an eighth illustrative embodiment of the process for decomposing a spent sulfuric acid stream or other sulfur-containing stream, the process of the seventh illustrative embodiment is provided, in which oxygen is injected into at least one of (i) piping upstream of the combustion air heater, (ii) piping downstream of the combustion air heater, (iii) or into the combustion air heater, to prepare oxygen-enriched combustion air.

[0082] According to a ninth illustrative embodiment of the process for decomposing a spent sulfuric acid stream or another sulfur-containing stream, the process is provided for any one of the first through eighth illustrative embodiments, in which pure oxygen is heated before the step of supplying pure oxygen to the furnace.

[0083] According to a tenth modality Petition 870250108701, dated 11 / 27 / 2025, page 33 / 54 Figure 29 / 35 illustrates the process for decomposing a spent sulfuric acid stream or another sulfur-containing stream; the process is provided for any one of the first through ninth illustrative embodiments, in which oxygen-enriched combustion air and pure oxygen are supplied to the furnace through separate pipes.

[0084] According to an eleventh illustrative embodiment of the process for decomposing a spent sulfuric acid stream or another sulfur-containing stream, the process is provided for any one of the first through tenth illustrative embodiments, in which pure oxygen is supplied to the furnace through at least one injector or injection point.

[0085] According to a twelfth illustrative embodiment of the process for decomposing a spent sulfuric acid stream or another sulfur-containing stream, the process is provided for any one of the second through eleventh illustrative embodiments, in which the oxygen-enriched combustion air and the fuel are supplied to the furnace through separate pipes.

[0086] Illustrative embodiments of the apparatus for use in the process for regenerating a spent acid stream or other acid precursor-containing stream of the present disclosure include:

[0087] In a first illustrative embodiment, an apparatus is provided for use in a process of regenerating a spent sulfuric acid stream or other sulfur-containing stream, wherein the apparatus comprises a decomposition furnace; an inlet for supplying at least one of the spent sulfuric acid feed or other sulfur-containing stream to the decomposition furnace; an inlet for Petition 870250108701, dated 11 / 27 / 2025, page 34 / 54 30 / 35 provide an oxygen-enriched combustion air supply to the decomposition furnace; an inlet to supply pure oxygen to the decomposition furnace separately from the oxygen-enriched combustion air supply; and an inlet to supply combustion fuel to the decomposition furnace.

[0088] According to a second illustrative embodiment, an apparatus is provided for use in a regeneration process of a spent sulfuric acid stream or other sulfur-containing stream of the first embodiment, wherein the apparatus further comprises a supply of at least one of the spent sulfuric acid or other sulfur-containing stream in fluid communication with the furnace.

[0089] According to a third illustrative embodiment, an apparatus is provided for use in a regeneration process of a spent sulfuric acid stream or other sulfur-containing stream of the first or second illustrative embodiments, wherein the apparatus comprises a supply of pure oxygen in fluid communication with the furnace.

[0090] According to a fourth illustrative embodiment, an apparatus is provided for use in a process of regenerating a spent sulfuric acid stream or other sulfur-containing stream from any of the first to the third illustrative embodiments, wherein the apparatus further comprises a combustion air supply in fluid communication with the furnace.

[0091] According to a fifth illustrative embodiment, an apparatus is provided for use in a process of regenerating a spent sulfuric acid stream or Petition 870250108701, dated 11 / 27 / 2025, page 35 / 54 31 / 35 another stream containing sulfur of any of the first to fourth illustrative embodiments, wherein the apparatus further comprises means for combining pure oxygen from the pure oxygen supply with combustion air.

[0092] According to a sixth illustrative embodiment, an apparatus is provided for use in a process of regenerating a spent sulfuric acid stream or other sulfur-containing stream of any of the first through fifth illustrative embodiments, wherein the apparatus further comprises a combustion fuel supply in fluid communication with the furnace.

[0093] Illustrative embodiments of the process for preparing sulfuric acid from a regenerated sulfuric acid stream or other sulfur-containing stream of the present disclosure include:

[0094] According to a first embodiment of the process for preparing sulfuric acid from a spent sulfuric acid stream or other sulfur-containing stream, the process is provided comprising supplying the spent sulfuric acid stream or other sulfur-containing stream to a furnace; supplying oxygen-enriched combustion air to the furnace; separately supplying pure oxygen to the furnace; oxidizing the spent sulfuric acid stream or other sulfur-containing stream in the furnace; and converting the sulfur dioxide into sulfuric acid.

[0095] According to a second illustrative embodiment of the process for preparing sulfuric acid from sulfur dioxide recovered from a regenerated spent sulfuric acid stream or other sulfur-containing stream, the process of the first embodiment for preparing Petition 870250108701, dated 11 / 27 / 2025, page 36 / 54 32 / 35 sulfuric acid, which further includes the introduction of a combustion fuel into the furnace.

[0096] According to a third illustrative embodiment of the process for preparing sulfuric acid from sulfur dioxide recovered from a regenerated sulfuric acid stream or another sulfur-containing stream, the process of the first or second illustrative embodiments for preparing sulfuric acid is provided, in which the step of separately supplying pure oxygen to the furnace comprises injecting the pure oxygen into or near the periphery of the primary flame of one or more furnace burners.

[0097] According to a fourth illustrative embodiment of the process for preparing sulfuric acid from sulfur dioxide recovered from a regenerated sulfuric acid stream or another sulfur-containing stream, the process is provided for any one of the first through third illustrative embodiments for preparing sulfuric acid, in which the oxygen-enriched combustion air is heated before the step of supplying the oxygen-enriched combustion air to the furnace.

[0098] According to a fifth illustrative embodiment of the process for preparing sulfuric acid from sulfur dioxide recovered from a regenerated spent sulfuric acid stream or other sulfur-containing stream, the process of any one of the first through fourth illustrative embodiments for preparing sulfuric acid is provided, wherein, before the step of supplying oxygen-enriched combustion air to the furnace, oxygen is injected into the preheated combustion air to prepare the oxygen-enriched combustion air. Petition 870250108701, dated 11 / 27 / 2025, p. 37 / 54 33 / 35

[0099] According to a sixth illustrative embodiment of the process for preparing sulfuric acid from sulfur dioxide recovered from a regenerated sulfuric acid stream or other sulfur-containing stream, the process of any one of the first through fifth illustrative embodiments for preparing sulfuric acid is provided, wherein oxygen is injected into at least one of (i) piping upstream of the heater to the combustion air, (ii) piping downstream of the heater to the combustion air, or (iii) into the heater to the combustion air to prepare oxygen-enriched combustion air.

[00100] According to a seventh illustrative embodiment of the process for preparing sulfuric acid from sulfur dioxide recovered from a regenerated spent sulfuric acid stream or other sulfur-containing stream, the process is provided for any one of the first through sixth illustrative embodiments for preparing sulfuric acid, in which pure oxygen is heated before the step of supplying pure oxygen to the furnace.

[00101] According to an eighth illustrative embodiment of the process for preparing sulfuric acid from sulfur dioxide recovered from a regenerated spent sulfuric acid stream or other sulfur-containing stream, the process is provided for any one of the first through seventh illustrative embodiments for preparing sulfuric acid, in which oxygen-enriched combustion air and pure oxygen are supplied to the furnace through separate pipes.

[00102] According to a ninth illustrative embodiment of the process for preparing sulfuric acid from dioxide Petition 870250108701, dated 11 / 27 / 2025, pp. 38 / 54 34 / 35 of sulfur recovered from a regenerated spent sulfuric acid stream or other sulfur-containing stream, is provided the process of any one of the first through eighth illustrative embodiments for preparing sulfuric acid, wherein pure oxygen is supplied to the furnace through at least one injector or injection point.

[00103] According to a tenth illustrative embodiment of the process for preparing sulfuric acid from sulfur dioxide recovered from a regenerated spent sulfuric acid stream or other sulfur-containing stream, the process of any one of the first through ninth illustrative embodiments for preparing sulfuric acid is provided, in which the oxygen-enriched combustion air and fuel are supplied to the furnace through separate piping.

[00104] According to another illustrative embodiment of the process for decomposing at least one of a spent sulfuric acid stream or another sulfur-containing stream, the detection of an amount of oxygen is provided both in the oxygen-enriched combustion air supplied to the furnace and in a furnace outlet stream; and the adjustment of the amount of oxygen supplied as necessary to the oxygen-enriched combustion air.

[00105] According to yet another illustrative embodiment of the apparatus for regenerating at least one of a spent sulfuric acid stream or another sulfur-containing stream, a first sensor is provided to detect an initial quantity of oxygen in the oxygen-enriched combustion air and generate a first signal representing the initial quantity of oxygen; a second Petition 870250108701, dated 11 / 27 / 2025, page 39 / 54 35 / 35 sensor to detect a second quantity of oxygen in an outlet stream from the decomposition furnace and generate a second signal representing the second quantity of oxygen; wherein the first and second quantities of oxygen detected determine a quantity of oxygen to be present in the oxygen-enriched combustion air supplied to the decomposition furnace.

[00106] It will be understood that the embodiments described herein 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 as set forth in the appended claims. It should be understood that the embodiments described above are not only alternatives, but may be combined. Petition 870250108701, dated 11 / 27 / 2025, pp. 40 / 54

Claims

1 / 2 CLAIMS 1. PROCESS FOR DECOMPOSING AT LEAST ONE OF A STREAM OF SPENT SULFURIC ACID OR OTHER SULFUR-CONTAINING STREAM, characterized by comprising: supplying one of the spent sulfuric acid streams or the other sulfur-containing stream to a furnace, decomposing the spent sulfuric acid stream; supplying oxygen-enriched combustion air to the furnace; supplying pure oxygen to the furnace; wherein the supply of pure oxygen to the furnace is carried out by injecting the pure oxygen into or near a periphery of a primary flame of one or more furnace burners; wherein the supply of pure oxygen is intended for the furnace through one or a plurality of injectors; supplying a combustion fuel to the furnace; decomposing one of the spent sulfuric acid streams or other sulfur-containing stream in the furnace; detecting a quantity of oxygen both in the oxygen-enriched combustion air supplied to the furnace and in a furnace outlet stream;wherein a ratio between the oxygen distributed in the enriched air stream and in one or more injectors is determined based on a temperature measured near a flame or on a theoretical adiabatic temperature of a fuel / air / oxygen mixture distributed through burners; and adjusting the amount of oxygen supplied to the oxygen-enriched combustion air as necessary for the decomposition of a spent sulfuric acid stream or other sulfur-containing stream in the furnace.

2. PROCESS, according to claim 1, characterized by comprising the decomposition of at least one other sulfur-containing stream.

3. PROCESS, according to claim 1, characterized by comprising the decomposition of both the spent sulfuric acid stream and another stream containing sulfur.

4. PROCESS, according to claim 1, characterized in that the oxygen-enriched combustion air is heated before supplying the oxygen-enriched combustion air to the furnace.

5. PROCESS, according to claim 4, characterized in that, before supplying oxygen-enriched combustion air to the furnace, oxygen is injected into the combustion air to prepare the oxygen-enriched combustion air.

6. PROCESS, according to claim 1, characterized in that pure oxygen is heated before supplying the pure oxygen to the furnace.

7. PROCESS, according to claim 1, characterized in that oxygen-enriched combustion air and pure oxygen are supplied to the furnace through separate pipes.

8. PROCESS, according to claim 1, characterized in that the oxygen-enriched combustion air and combustion fuel are supplied to the furnace through separate piping. Petition 870260065600, dated 03 / 07 / 2026, page 8 / 15

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