TWI903721B - Systems and methods for sub-dewpoint sulfur recovery - Google Patents

Abstract

Systems and methods for sub-dewpoint sulfur recovery using a separation device and/or an interstage heater to improve the performance of a single (catalytic) step sulfur recovery system without the need for a thermal step or an additional catalyst. The sulfur bearing compounds are removed at a higher pressure than traditional Claus operating pressures prior to additional feed gas processing. The main reaction in the Claus-type process used to convert the sulfur species to elemental sulfur is:2H2S + SO2 → 3S + 2H2O where SO2 may be used as the oxidant for the Claus catalytic reaction.

Description

Systems and methods for sulfur recovery at dew point

This invention relates to systems and methods for recovering sulfur at near-dew points. More specifically, these systems and methods utilize separation devices and/or interstage heaters to improve the performance of single (catalytic)-step sulfur recovery systems without requiring a thermal step or additional catalyst.

The removal and recovery of sulfur compounds from high-pressure gas streams typically involves a two-step process: an amine or physical solvent sulfur removal step, followed by a Claus-type process to convert the sulfur compounds into elemental sulfur. This usually requires cooling the gas to ambient temperature or lower before processing. Additionally, the sulfur removal step typically removes some carbon dioxide and generates a low-pressure carbon dioxide stream, and/or the carbon dioxide can be supplied as a low-pressure gas stream along with hydrogen sulfide to the Claus sulfur recovery unit.

The Bechtel Pressure Swing Claus (BPSC) process is a single-step sulfur removal and recovery technology operating at full pressure and intermediate temperatures. This technology reduces equipment capital costs and improves operational efficiency through amine elimination treatment, and provides a high-purity carbon dioxide stream for subsequent applications, if needed. The process involves: gas treatment; _H₂S and COS reactions on a conventional Claus catalyst under sub-dew point conditions; and regeneration via pressure swing and/or heating. This allows sulfur formation, collection, and separation to be achieved in a single step. Multiple reaction stages can be used to achieve extremely low sulfur content in the treated gas.

The effectiveness of the high-pressure sulfur condenser in a BPSC system depends on the temperature of the cooling medium, which is directly related to its pressure. The high-pressure sulfur condenser operates using a cooling medium with relatively efficient heat transfer, but on the other side, it uses a process gas flow with relatively inefficient heat transfer. Variations in flow rate or inlet temperature (based on upstream reactor activity) can alter the efficiency of the high-pressure sulfur condenser and thus the temperature of the gas entering the secondary (lag) reactor. Furthermore, any mist not properly separated from the gas in the outlet charge chamber of the high-pressure sulfur condenser can cause premature aging of the catalyst in the secondary (lag) reactor.

100: Single-step sulfur recovery system

102: Pressurized intake (e.g., synthesis gas) flow

104:SO ₂ stream

105: Mixed Flow

106: Reactor feed heater

108: Separation device (e.g., liquid-gas separator)

110: First liquid flow

112: Vapor Flow

114: Heated steam flow

116: First-stage (pilot) high-pressure sub-dew point reactor

118: Catalyst Bed

120: Processed vapor stream

122: High-pressure sulfur condenser

123: Second Liquid Flow

124: First cooled vapor stream

125: Interstage heater for reactors

126: Another heated steam stream

128: Second-stage (lag) high-pressure sub-dew point reactor

130: Catalyst Bed

132: Product vapor flow

134: Regenerative High-Pressure Sub-Dew Point Reactor

135: Clean and virtually sulfur-free catalyst bed

136: Flash gas vapor flow

138: Low-pressure sulfur condenser

139: Third Liquid Flow

140: Second cooled vapor stream

142: Regenerative Compressor

144: Blowing away the air

145a: Valve

145b: Valve

146: Heated and purged airflow

148: Pressurized gas (e.g., synthesis gas) flow

150: Heater

152: Recirculating Compressor

200: Single-step sulfur recovery system

202: Storage Device

203: Fourth Liquid Flow

204: Fifth Liquid Flow

206: Oxidizer

207: Oxidizing agent

208: First-order fluid flow

The embodiments are described below with reference to the accompanying figures, wherein similar reference numerals are used to refer to similar components, and wherein:

Figure 1 is a schematic diagram illustrating one embodiment of a single-step sulfur recovery system, which includes a separation device and an interstage heater.

Figure 2 is a schematic diagram illustrating another embodiment of a single-step sulfur recovery system that recycles elemental sulfur generated by the system.

Cross-referencing of related applications

This application claims priority to U.S. Provisional Application No. 63/579,323, filed August 29, 2023, which is incorporated herein by reference.

The subject matter of this invention has been specifically described; however, this description itself is not intended to limit the scope of the invention. Therefore, the subject matter may also be embodied in other ways in conjunction with other current or future techniques to include different structures, steps, and/or combinations similar to and/or fewer than those described herein. Although the term "step" is used herein to describe different elements of the methods used, it should not be construed as implying any particular order among or between the steps disclosed herein, unless the description expressly specifies a particular order. Further features and advantages of the disclosed embodiments will, or will become, apparent to those skilled in the art upon examination of the following figures and detailed description. All such additional features and advantages are included within the scope of the disclosed embodiments. Furthermore, the figures illustrated herein are for illustrative purposes only and are not intended to assert or imply any limitations on the environment, architecture, design, or process in which different embodiments may be implemented. Regarding the temperature and/or pressure mentioned below, these conditions are illustrative only and are not intended to limit the invention. All illustrative flows are transmitted via physical lines.

The system and method disclosed herein improve the performance of a single-step sulfur recovery system by utilizing a separation device and/or an interstage heater without requiring a thermal step or additional catalyst. Sulfur compounds are removed at pressures higher than the conventional Krauss operating pressure prior to additional inlet treatment. The main reaction system used in Krauss-type processes to convert sulfur substances into elemental sulfur is: _2H₂S + _SO₂ → 3S + _2H₂O

_SO2 is used as the oxidant in the Claus catalytic reaction. The catalytic recovery of sulfur consists of the following three sub-steps: heating, catalytic reaction, and cooling + condensation.

In one embodiment, a system for sulfur recovery is disclosed, comprising: i) a primary feed stream comprising elemental sulfur; ii) a separation device connected to the primary feed stream fluid for separating the primary feed stream into a first liquid stream comprising elemental sulfur and a vapor stream comprising sulfur vapor; iii) a first heater connected to the separation device via the vapor stream fluid for generating a heated vapor stream; and iv) a primary reactor connected to the first heater via the heated vapor stream fluid, the primary reactor comprising a catalyst for adsorbing elemental sulfur from the heated vapor stream and generating a treated vapor stream comprising sulfur vapor.

In another embodiment, a method for sulfur recovery is disclosed, comprising: i) separating a primary feed stream into a first liquid stream comprising elemental sulfur and a vapor stream comprising sulfur vapor; ii) heating the vapor stream to generate a heated vapor stream; iii) adsorbing elemental sulfur from the heated vapor stream onto a catalyst; and iv) generating a treated vapor stream comprising sulfur vapor.

In another embodiment, a system for sulfur recovery is disclosed, comprising: i) a primary reactor having a catalyst for adsorbing elemental sulfur from a primary feed stream and generating a treated vapor stream comprising sulfur vapor; ii) a first condenser connected to the primary reactor via the treated vapor stream for converting the treated vapor stream into a first liquid stream comprising elemental sulfur and a first cooled vapor stream; and iii) a heater connected to the first condenser via the first cooled vapor stream for generating a heated vapor stream.

In another embodiment, a method for sulfur recovery is disclosed, comprising: i) adsorbing elemental sulfur from a primary feed stream onto a catalyst; ii) generating a treated vapor stream comprising sulfur vapor; iii) converting the treated vapor stream into a first liquid stream comprising elemental sulfur and a first cooled vapor stream; and iv) generating a heated vapor stream.

In another embodiment, a system for sulfur recovery is disclosed, comprising: i) a primary reactor having a catalyst for adsorbing elemental sulfur from a primary feed stream and generating a treated vapor stream including sulfur vapor; ii) a first condenser connected to the primary reactor via the treated vapor stream fluid for converting the treated vapor stream into a first liquid stream including elemental sulfur and a first cooled vapor stream; iii) a regeneration reactor connected to the primary feed stream fluid for regenerating the catalyst including the adsorbed elemental sulfur and generating a flash gas vapor stream including elemental sulfur; iv) a second condenser connected to the regeneration reactor via the flash gas vapor stream fluid for converting the flash gas into a liquid stream including elemental sulfur and a first cooled vapor stream. The gas vapor stream is converted into a second liquid stream comprising elemental sulfur and a second cooled vapor stream; v) an oxidizer connected to the first and second liquid streams for converting the elemental sulfur in the first and second liquid streams into a secondary feed stream comprising at least one of thiosulfate, sulfur dioxide, sulfur trioxide, sulfuric acid, and sulfurous acid; and vi) another secondary feed stream comprising hydrogen sulfide, wherein the secondary feed stream and the other secondary feed stream are connected to the primary feed stream for converting at least one of thiosulfate, sulfur dioxide, sulfur trioxide, sulfuric acid, and sulfurous acid in the secondary feed stream and hydrogen sulfide in the other secondary feed stream into elemental sulfur in the primary feed stream.

In another embodiment, a method for sulfur recovery is disclosed, comprising: i) adsorbing elemental sulfur from a primary feed stream onto a catalyst; ii) generating a treated vapor stream including sulfur vapor; iii) converting the treated vapor stream into a first liquid stream including elemental sulfur and a first cooled vapor stream; iv) regenerating the catalyst including the adsorbed elemental sulfur; v) generating a flash gas vapor stream including elemental sulfur; vi) converting the flash gas vapor stream into... The process involves: (i) forming a second liquid stream and a second cooled vapor stream; (ii) converting elemental sulfur in the first and second liquid streams into a secondary feed stream comprising at least one of thiosulfate, sulfur dioxide, sulfur trioxide, sulfuric acid, and sulfurous acid; and (viii) converting at least one of thiosulfate, sulfur dioxide, sulfur trioxide, sulfuric acid, and sulfurous acid in the secondary feed stream, and hydrogen sulfide in another secondary feed stream, into elemental sulfur in the primary feed stream.

Referring now to Figure 1 , a schematic diagram of a single-step sulfur recovery system 100 is illustrated. This system includes a separation device (e.g., a liquid-gas separator) 108 and an interstage heater 125. A pressurized inlet gas stream (e.g., syngas) 102 containing hydrogen sulfide ( _H₂S ) is mixed with a stream 104 containing a high concentration of sulfur dioxide ( _SO₂ ). The inlet gas stream 102 and the _SO₂ stream 104 can be gaseous and/or liquid. Where the _SO₂ stream 104 is introduced into the inlet gas stream 102 , it undergoes a non-catalytic reaction with the _H₂S in the inlet gas stream 102. Because the _SO₂ stream 104 is at a high concentration, it readily reacts with the _H₂S (low or high concentration) present in the inlet gas stream 102 to form a mixed stream 105 containing elemental sulfur. Given that the newly formed elemental sulfur in the mixed stream 105 contains a liquid phase, a separation device 108 can be used to separate the mixed stream 105 into a first liquid stream 110 containing elemental sulfur and a vapor stream 112 containing sulfur vapor and unreacted components. The separation device 108 can be positioned horizontally, vertically, or at an angle and can remove elemental sulfur without any additional catalyst. The separation device 108 reduces catalyst requirements, extends regeneration time, and increases catalyst lifetime because some of the elemental sulfur is removed before being introduced into the catalyst bed (reactor bed). The presence of liquid sulfur also allows for the washing of the mixed stream 105 , removing any heavier molecular weight contaminants that are detrimental to product purity and catalyst activity and reduce expected catalyst lifetime. The first liquid stream 110 containing elemental sulfur can be transported to a separate storage device.

Steam stream 112 travels to reactor feed heater 106 , where it is heated to 240-1000℉ (preferably 300-400℉), which helps optimize the reaction temperature. Heated steam stream 114 is supplied to primary (pilot) high-pressure sub-dew point reactor 116 , where most of the _H₂S , COS, and _SO₂ are converted into elemental sulfur and adsorbed onto a catalyst bed 118 comprising alumina, activated alumina, and/or γ-activated alumina. Depending on the temperature, pressure, and composition of the inlet stream 102 , primary reactor 116 is expected to produce a sweet odor at a total sulfur content of 500 ppmv (typically 200 ppmv). The sweet gas forms a treated vapor stream 120 , comprising sulfur vapor and unreacted components, within 200℉ of the inlet temperature of the first-stage reactor. This treated vapor stream is conveyed to a high-pressure sulfur condenser 122 to cool the treated vapor stream 120 to within 100-500℉ (preferably within 250-280℉) and remove some residual elemental sulfur in the outlet filling chamber (not shown) of the high-pressure sulfur condenser 122 as a second liquid stream 123 containing elemental sulfur. Heat (e.g., steam) is generated on the shell side (not shown) of the high-pressure sulfur condenser 122 using the cooling of the flow and condensation heat.

The remaining gas forms a first cooled vapor stream 124 , comprising sulfur vapor and unreacted components, at 100-500℉ (preferably 250-280℉). This first cooled vapor stream is then conveyed to the reactor interstage heater 125 , where it is heated to a temperature 5-100℉ (more preferably 300-325℉) above the reactor interstage heater inlet temperature. Heating the first cooled vapor stream 124 in this manner helps control the temperature of the gas entering the secondary (lag) high-pressure sub-dew point reactor 128 as another heated vapor stream 126. Because sulfur recovery efficiency is greatly affected by temperature, process control is crucial to the operation of system 100 . The interstage heater 125 also reduces (if not eliminated) any sulfur mist that is not properly separated from the vapor in the outlet charge chamber of the high-pressure sulfur condenser 122 , which can prematurely age the catalyst in the secondary reactor 128. The interstage heater 125 will thus improve reliability and reduce operating costs by reducing catalyst replacements.

Another heated vapor stream 126 is supplied to a secondary reactor 128 , where most of the residual _H₂S , COS, and _SO₂ are converted into elemental sulfur on a catalyst bed 130 comprising alumina, activated alumina, and/or γ-activated alumina. The secondary reactor 128 is designed to reduce the sulfur content in the product gas to 20 ppmv or less, preferably 4 ppmv or less. The residual gas forms a product vapor stream 132 comprising sulfur vapor and unreacted components within 50°F of the secondary reactor inlet temperature. This product vapor stream can be used for additional processing, such as compression and liquefaction, combustion for power generation in turbine generators, or separation into basic chemicals for the production of specialty chemicals.

After the catalyst bed 118 of the primary reactor 116 is saturated with adsorbed sulfur, the primary reactor 116 is rotated to replace the regenerated high-pressure sub-dew point reactor 134 with a clean and substantially sulfur-free catalyst bed 135 , including alumina, activated alumina, and/or γ-activated alumina. The regenerated reactor 134 replaces the secondary reactor 128 , which in turn replaces the primary reactor 116. In its new position, the regenerated reactor 134 and the secondary reactor 128 perform the functions of the reactors they replaced, while the catalyst bed 118 in the primary reactor 116 is regenerated by pressure reduction. The pressure reduction generates a flash gas vapor stream 136 , comprising elemental sulfur and adsorbed and unadsorbed components, at approximately the same temperature (preferably 300-400℉) as the treated vapor stream 120. This flash gas is conveyed to a low-pressure sulfur condenser 138 for cooling to approximately 100-500℉ (more preferably 250-280℉) and removing elemental sulfur from the outlet charge chamber (not shown) of the low-pressure sulfur condenser 138 as a third liquid stream 139 containing elemental sulfur. Cooling using the heat of flow and condensation generates heat (e.g., steam) on the shell side (not shown) of the low-pressure sulfur condenser 138 .

The remaining gas forms a second cooled vapor stream 140 , comprising elemental sulfur and adsorbed and unadsorbed components, at approximately 100-500℉ (more preferably 250-280℉). This second cooled vapor stream is conveyed to a regeneration compressor 142 for compression in the purge gas loop. After the second cooled vapor stream 140 is compressed to approximately 10-200 psig (more preferably 45 psig) in the regeneration compressor 142 , it forms purge gas 144 , which can be guided through valves 145a and/or 145b . The purge gas passing through valve 145a may be delivered (as appropriate) i) to heater 150 or ii) to regeneration reactor. The purge gas passing through valve 145b may be delivered (as appropriate) i) to recirculation compressor 152 for further compression and/or mixing with intake air stream 102 , or ii) to recirculation compressor 152 and/or exit system 100. Recirculation compressor 152 forms a pressurized gas (e.g., syngas) stream 148 that may be mixed with intake air stream 102 or delivered to the outside of system 100 . The regeneration compressor 142 and the recirculation compressor 152 can be used individually or in combination to depressurize the regeneration reactor to a pressure of -5 to 100 psig (more preferably 10 to 20 psig). After depressurization of the regeneration reactor, the flow through valve 145b is essentially terminated. The regeneration of the catalyst bed used in the regeneration reactor can be promoted at a temperature of 300 to 900℉ (more preferably 500 to 700℉) using heater 150. Heated purge gas flow 146 passes through the regeneration reactor to evaporate the adsorbed components from the catalyst bed. The regeneration process is repeated until sufficient sulfur (preferably most of it) is removed from the catalyst bed, thereby allowing the regeneration reactor to be put back into service. After sufficient sulfur removal, the heater 150 can be used as a cooler by changing the heat exchange medium to a cooling medium, and then the catalyst bed can be cooled to the expected reaction temperature of about 300-400℉ or nearby using purge air 144. At this time, the regeneration reactor can be left idle until the current stage reactor needs regeneration, at which point the reactor will be switched as described above.

Referring now to Figure 2 , a schematic diagram of a single-step sulfur recovery system 200 is illustrated, which recycles elemental sulfur produced by system 200. System 200 includes the same components as system 100 of Figure 1 , which perform the same functions as described in Figure 1. However, elemental sulfur in the first liquid stream 110 , the second liquid stream 123 , and the third liquid stream 139 is recycled to reduce the amount of SO2 stored on-site. Because sulfur oxides (e.g., thiosulfates (S2O3), sulfur dioxide (SO2), sulfur trioxide (SO3), sulfuric acid (H2SO4), and/or sulfurous acid (H2SO3)) are toxic to humans and the environment, generating any of these substances as needed is superior to on-site storage and represents cost savings for the facility.

The first liquid stream 110 , the second liquid stream 123 , and the third liquid stream 139 are conveyed to a storage device 202 for collection. The storage device 202 is used to generate a fourth liquid stream 203 containing elemental sulfur and a fifth liquid stream 204 also containing elemental sulfur. The fourth liquid stream 203 is conveyed to the oxidizer 206 , and the fifth liquid stream 204 is conveyed outside the boundary as a sulfur byproduct. Alternatively, the second liquid stream 123 and the third liquid stream 139 can be combined with the first liquid stream 110 into a single stream, which can be separated into the fourth liquid stream 203 and the fifth liquid stream 204 using one or more valves. Oxidant 207 is added to the fourth liquid stream 203 in oxidizer 206 , which generates a first fluid stream 208 comprising _{thiosulfate (S₂O₃ )} , sulfur dioxide ( _SO₂ ), sulfur trioxide ( _SO₃ ), sulfuric acid ( _H₂SO₄ ), and/or _sulfurous acid ( _H₂SO₃ ). Oxidant 207 can be, for example, atmospheric oxygen, purified oxygen, ozone, permanganate, hypochlorite, and/or peroxides. The first fluid stream 208 can then be combined with SO₂ stream 104 _to reduce _SO₂ demand _. Alternatively, the oxidant 207 may be, for example, _H₂SO₄ , _H₂SO₃ , and/or _SO₃ , which _, when added to the fourth liquid stream 203 in the oxidizer 206 _, will generate a first fluid stream ₂₀₈ comprising _S₂O₃ and/or _SO₂ .

Although the present invention has been described in conjunction with presently preferred embodiments, those skilled in the art will understand that it is not intended to limit the disclosure of those embodiments. Therefore, various alternative embodiments and modifications may be considered to the disclosed embodiments without departing from the spirit and scope of the present invention as defined by the appended patent claims and their equivalents.

100: Single-step sulfur recovery system

102: Pressurized intake (e.g., synthesis gas) flow

104:SO ₂ stream

105: Mixed Flow

106: Reactor feed heater

108: Separation device (e.g., liquid-gas separator)

110: First liquid flow

112: Vapor Flow

114: Heated steam flow

116: First-stage (pilot) high-pressure sub-dew point reactor

118: Catalyst Bed

120: Processed vapor stream

122: High-pressure sulfur condenser

123: Second Liquid Flow

124: First cooled vapor stream

125: Interstage heater for reactors

126: Another heated steam stream

128: Second-stage (lag) high-pressure sub-dew point reactor

130: Catalyst Bed

132: Product vapor flow

134: Regenerative High-Pressure Sub-Dew Point Reactor

135: Clean and virtually sulfur-free catalyst bed

136: Flash gas vapor flow

138: Low-pressure sulfur condenser

139: Third Liquid Flow

140: Second cooled vapor stream

142: Regenerative Compressor

144: Blowing away the air

145a: Valve

145b: Valve

146: Heated and purged airflow

148: Pressurized gas (e.g., synthesis gas) flow

150: Heater

152: Recirculating Compressor

Claims (26)

A sulfur recovery system includes: a primary feed stream comprising elemental sulfur; a separation device connected to the primary feed stream for separating the primary feed stream into a first liquid stream comprising elemental sulfur and a vapor stream comprising sulfur vapor; a first heater connected to the separation device via the vapor stream for generating a heated vapor stream; a primary reactor connected to the first heater via the heated vapor stream, the primary reactor including a catalyst for adsorbing elemental sulfur from the heated vapor stream and generating a treated vapor stream comprising sulfur vapor; and a first condenser connected to the primary reactor via the treated vapor stream for converting the treated vapor stream into a second liquid stream comprising elemental sulfur and a first treated vapor stream comprising sulfur vapor. The system comprises: a cooled vapor stream; a second heater connected to the first condenser via the first cooled vapor stream to generate another heated vapor stream; a secondary reactor connected to the second heater via the other heated vapor stream, the secondary reactor including a catalyst for adsorbing elemental sulfur from the other heated vapor stream and generating a product vapor stream including sulfur vapor; a regeneration reactor connected to the first feed stream to regenerate the catalyst including the adsorbed elemental sulfur and generate a flash gas vapor stream including elemental sulfur; and a second condenser connected to the regeneration reactor via the flash gas vapor stream to convert the flash gas vapor stream into a third liquid stream including elemental sulfur and a second cooled vapor stream. The sulfur recovery system of claim 1 further includes an oxidizer connected to the first, second, and third liquid streams for converting elemental sulfur in the first, second, and third liquid streams into a secondary feed stream comprising at least one of thiosulfate, sulfur dioxide, sulfur trioxide, sulfuric acid, and sulfurous acid. The sulfur recovery system of claim 2 further includes another secondary feed stream containing hydrogen sulfide, wherein the secondary feed stream and the other secondary feed stream are fluidly connected to the primary feed stream for converting at least one of thiosulfate, sulfur dioxide, sulfur trioxide, sulfuric acid, and sulfurous acid in the secondary feed stream, and the hydrogen sulfide in the other secondary feed stream, into elemental sulfur in the primary feed stream. For example, in the sulfur recovery system of claim 3, each catalyst includes at least one of alumina, activated alumina, and gamma-activated alumina. For example, the sulfur recovery system in claim 1, wherein the sulfur vapor in the product vapor stream contains less than 20 ppmv of sulfur. For example, the sulfur recovery system in claim 1, wherein the heated steam flow is 240℉ to 400℉. For example, in the sulfur recovery system of claim 1, the other heated steam stream is between 240℉ and 325℉. A sulfur recovery method includes: separating a primary feed stream into a first liquid stream comprising elemental sulfur and a vapor stream comprising sulfur vapor; heating the vapor stream to generate a heated vapor stream; adsorbing elemental sulfur from the heated vapor stream onto a catalyst; generating a treated vapor stream comprising sulfur vapor; converting the treated vapor stream into a second liquid stream comprising elemental sulfur and a first cooled vapor stream; heating the first cooled vapor stream to generate another heated vapor stream; adsorbing elemental sulfur from the other heated vapor stream onto a catalyst; generating a product vapor stream comprising sulfur vapor; regenerating the catalyst comprising adsorbed elemental sulfur; generating a flash gas vapor stream comprising elemental sulfur; and converting the flash gas vapor stream into a third liquid stream and a second cooled vapor stream. The sulfur recovery method of claim 8 further includes converting the elemental sulfur in the first liquid stream, the second liquid stream, and the third liquid stream into a secondary feed stream comprising at least one of thiosulfate, sulfur dioxide, sulfur trioxide, sulfuric acid, and sulfurous acid. The sulfur recovery method of claim 9 further includes converting at least one of thiosulfate, sulfur dioxide, sulfur trioxide, sulfuric acid, and sulfurous acid in the secondary feed stream, and hydrogen sulfide in the other secondary feed stream, into elemental sulfur in the primary feed stream. For example, the sulfur recovery method in claim 10, wherein each catalyst includes at least one of alumina, activated alumina, and γ-activated alumina. As in the sulfur recovery method of claim 8, wherein the sulfur vapor in the product vapor stream contains less than 20 ppmv of sulfur. For example, the sulfur recovery method in claim 8, wherein the heated steam flow is 240℉ to 400℉. For example, in the sulfur recovery method described in claim 8, the other heated steam stream is between 240℉ and 325℉. A sulfur recovery system includes: a first-stage reactor having a catalyst for adsorbing elemental sulfur from a first-stage feed stream and generating a treated vapor stream including sulfur vapor; a first condenser connected to the first-stage reactor via the treated vapor stream for converting the treated vapor stream into a first liquid stream including elemental sulfur and a first cooled vapor stream; a heater connected to the first condenser via the first cooled vapor stream for generating a heated vapor stream; and a second-stage reactor for generating a heated vapor stream. A vapor stream is connected to the heater; the secondary reactor includes a catalyst for adsorbing elemental sulfur from the heated vapor stream and generating a product vapor stream comprising sulfur vapor; a regeneration reactor connected to the primary feed stream for regenerating the catalyst containing the adsorbed elemental sulfur and generating a flash vapor stream comprising elemental sulfur; and a second condenser connected to the regeneration reactor via the flash vapor stream for converting the flash vapor stream into a second liquid stream comprising elemental sulfur and a second cooled vapor stream. The sulfur recovery system of claim 15 further includes an oxidizer connected to the first liquid stream and the second liquid stream for converting elemental sulfur in the first liquid stream and the second liquid stream into a secondary feed stream comprising at least one of thiosulfate, sulfur dioxide, sulfur trioxide, sulfuric acid, and sulfurous acid. The sulfur recovery system of claim 16 further includes another secondary feed stream containing hydrogen sulfide, wherein the secondary feed stream and the other secondary feed stream are fluidly connected to the primary feed stream for converting at least one of thiosulfate, sulfur dioxide, sulfur trioxide, sulfuric acid, and sulfurous acid in the secondary feed stream, and the hydrogen sulfide in the other secondary feed stream, into elemental sulfur in the primary feed stream. A sulfur recovery method includes: adsorbing elemental sulfur from a primary feed stream onto a catalyst; generating a treated vapor stream including sulfur vapor; converting the treated vapor stream into a first liquid stream and a first cooled vapor stream including elemental sulfur; heating the first cooled vapor stream to generate a heated vapor stream; adsorbing elemental sulfur from the heated vapor stream onto a catalyst; generating a product vapor stream including sulfur vapor; regenerating the catalyst containing the adsorbed elemental sulfur; generating a flash gas vapor stream including elemental sulfur; and converting the flash gas vapor stream into a second liquid stream and a second cooled vapor stream. The sulfur recovery method of claim 18 further includes converting the elemental sulfur in the first liquid stream and the second liquid stream into a secondary feed stream comprising at least one of thiosulfate, sulfur dioxide, sulfur trioxide, sulfuric acid, and sulfurous acid. The sulfur recovery method of claim 19 further includes converting at least one of thiosulfate, sulfur dioxide, sulfur trioxide, sulfuric acid, and sulfurous acid in the secondary feed stream, and hydrogen sulfide in the other secondary feed stream, into elemental sulfur in the primary feed stream. A sulfur recovery system includes: a first-stage reactor with a catalyst for adsorbing elemental sulfur from a first-stage feed stream and generating a treated vapor stream including sulfur vapor; a first condenser connected to the first-stage reactor via the treated vapor stream for converting the treated vapor stream into a first liquid stream including elemental sulfur and a first cooled vapor stream; a regeneration reactor connected to the first-stage feed stream for regenerating the catalyst including the adsorbed elemental sulfur and generating a flash gas vapor stream including elemental sulfur; and a second condenser connected to the regeneration reactor via the flash gas vapor stream for converting the flash gas vapor stream into a packaged liquid stream. The system comprises a second liquid stream of elemental sulfur and a second cooled vapor stream; an oxidizer connected to the first and second liquid streams for converting the elemental sulfur in the first and second liquid streams into a secondary feed stream comprising at least one of thiosulfate, sulfur dioxide, sulfur trioxide, sulfuric acid, and sulfurous acid; and another secondary feed stream comprising hydrogen sulfide, wherein the secondary feed stream and the other secondary feed stream are connected to the primary feed stream for converting at least one of thiosulfate, sulfur dioxide, sulfur trioxide, sulfuric acid, and sulfurous acid in the secondary feed stream and hydrogen sulfide in the other secondary feed stream into elemental sulfur in the primary feed stream. For example, the sulfur recovery system in claim 21, wherein the oxidizer contains an oxidant comprising at least one of atmospheric oxygen, pure oxygen, ozone, permanganate, hypochlorite, and peroxides. For example, the sulfur recovery system in claim 21, wherein the oxidizer contains an oxidant comprising at least one of sulfuric acid, sulfurous acid, and sulfur trioxide. A sulfur recovery method includes: adsorbing elemental sulfur from a primary feed stream onto a catalyst; generating a treated vapor stream containing sulfur vapor; converting the treated vapor stream into a first liquid stream and a first cooled vapor stream containing elemental sulfur; regenerating the catalyst containing the adsorbed elemental sulfur; generating a flash gas vapor stream containing elemental sulfur; converting the flash gas vapor stream into a second liquid stream and a second cooled vapor stream; converting the elemental sulfur in the first liquid stream and the second liquid stream into a secondary feed stream containing at least one of thiosulfate, sulfur dioxide, sulfur trioxide, sulfuric acid, and sulfurous acid; and converting at least one of thiosulfate, sulfur dioxide, sulfur trioxide, sulfuric acid, and sulfurous acid in the secondary feed stream and hydrogen sulfide in the other secondary feed stream into elemental sulfur in the primary feed stream. The sulfur recovery method of claim 24, wherein an oxidant comprising at least one of atmospheric oxygen, purified oxygen, ozone, permanganate, hypochlorite, and peroxides is used to convert elemental sulfur in the first liquid stream and the second liquid stream into the secondary feed stream. The sulfur recovery method of claim 24, wherein an oxidant including at least one of sulfuric acid, sulfurous acid and sulfur trioxide is used to convert the elemental sulfur in the first liquid stream and the second liquid stream into the secondary feed stream.