Methods and systems for sulphur combustion

Abstract

A method for generating energy from sulphur combustion without causing harmful emissions to the environment entails steps of evaporating liquid sulphur to generate sulphur dioxide gas and sulphur vapor, combusting the sulphur vapor with oxygen gas to generate heat, and reducing (either at high temperature or catalytically) the sulphur dioxide to carbon dioxide and sulphur vapor by reacting the sulphur dioxide with carbonyl sulfide. The carbonyl sulphide can be generated by reacting hydrogen sulfide with recycled carbon dioxide that is recycled by condensing sulphur vapor, carbon dioxide and water to yield liquid sulphur, elemental sulphur, steam and carbon dioxide. Energy in the hot reactor products (SO2 gas and sulphur vapor S2) and steam can be harnessed using this emission-free process. Likewise, this process can be used to produce elemental sulphur and/or carbon monoxide without polluting the atmosphere. Furthermore, this process can be used for the transshipment by pipeline of sulphur by transporting it as carbonyl sulphide.

1 . A method for generating thermodynamic energy from sulphur combustion, the method comprising steps of:
 evaporating liquid sulphur to generate sulphur dioxide (SO 2 ) gas and sulphur vapor (S 2 );   combusting the sulphur vapor (S 2 ) with oxygen gas (O 2 ) to generate sulphur dioxide (SO 2 ) gas and heat energy;   reducing the sulphur dioxide (SO 2 ) to carbon dioxide (CO 2 ) and sulphur vapor (S 2 ) by reacting the sulphur dioxide (SO 2 ) with carbonyl sulfide (COS) to generate energized reaction products; and   harnessing energy in the energized reaction products.   
   
   
       2 . The method as claimed in  claim 1  wherein the step of combusting the sulphur vapor (S 2 ) with oxygen gas (O 2 ) to generate thermal energy. 
   
   
       3 . The method as claimed in  claim 1  wherein the step of reducing the sulphur dioxide (SO 2 ) to carbon dioxide (CO 2 ) and sulphur vapor (S 2 ) is performed at a high temperature of at least 1000 degrees Celsius. 
   
   
       4 . The method as claimed in  claim 1  wherein the step of reducing the sulphur dioxide (SO 2 ) to carbon dioxide (CO 2 ) and sulphur vapor (S 2 ) is performed catalytically at a low temperature lower than 1000 degrees Celsius. 
   
   
       5 . The method as claimed in  claim 1  wherein sulphur dioxide interacts with the carbonyl sulphide at high temperature before harnessing the heat energy. 
   
   
       6 . The method as claimed in  claim 1  wherein the sulphur dioxide interacts with the carbonyl sulphide at low temperature after harnessing the heat energy. 
   
   
       7 . The method as claimed in  claim 1  further comprising a step of recycling the carbon dioxide (CO 2 ) for reacting with hydrogen sulfide (H 2 S) to generate the carbonyl sulphide (COS). 
   
   
       8 . The method as claimed in  claim 1  further comprising steps of:
 condensing the sulphur vapor (S 2 ) to yield liquid S 8  and elemental sulphur (S); and extracting the elemental sulphur (S).   
   
   
       9 . The method as claimed in  claim 1  wherein the step of combusting the sulphur vapor with oxygen gas is performed stoichiometrically. 
   
   
       10 . The method as claimed in  claim 1  wherein the step of combusting the sulphur vapor with oxygen gas is performed in a nearly stoichiometric interaction of sulphur and oxygen wherein the nearly stoichiometric interaction comprises an excess of sulphur in form of S 2 . 
   
   
       11 . The method as claimed in  claim 8  wherein the liquid S 8  is returned to a bubbling chamber supplied with oxygen (O 2 ) for generating SO 2  and sulphur vapour. 
   
   
       12 . The method as claim in  claim 11  further comprising steps of:
 maintaining a pool of molten sulphur in the bubbling chamber at or above its auto-ignition temperature; and   injecting oxygen gas beneath a surface of the pool of molten sulphur to cause the sulphur to vaporize.   
   
   
       13 . The method as claimed in  claim 1  wherein the step of harnessing energy in the energized reaction products comprises expending energy in a gas turbine. 
   
   
       14 . The method as claimed in  claim 1  wherein the step of harnessing energy in the energized reaction products comprises generating steam and expending energy in the steam by driving a steam turbine. 
   
   
       15 . The method as claimed in  claim 13  wherein the gas turbine is connected to an oxygen compressor for driving the oxygen compressor. 
   
   
       16 . The method as claimed in  claim 1  further comprising a step of using an ejector to perform pressure exchange and heat exchange between hot SO 2  gas emerging from the combustor and cooler COS gas that is recycled into the ejector. 
   
   
       17 . The method as claimed in  claim 16  wherein the COS gas is recycled into the ejector by re-association of COS in lower temperature process units and/or from a carbonyl sulphide (COS) generator into which hydrogen sulphide (H 2 S) and carbon dioxide (CO 2 ) are injected. 
   
   
       18 . The method as claimed in  claim 17  wherein the carbon dioxide injected into the COS generator is recycled from one or more heat recovery/sulphur condensation units. 
   
   
       19 . The method as claimed in  claim 18  wherein the recycled carbon dioxide is received from a condenser disposed downstream of a heat-recovery steam generator. 
   
   
       20 . The method as claimed in  claim 18  wherein the recycled carbon dioxide is received from a single unit comprising both a condenser and a heat-recovery steam generator. 
   
   
       21 . The method as claimed in  claim 17  wherein the carbonyl sulphide is generated in the liquid phase. 
   
   
       22 . The method as claimed in  claim 17  wherein the carbonyl sulphide is generated in the vapor phase. 
   
   
       23 . The method as claimed in  claim 17  wherein the carbonyl sulphide is generated in at least one dryer comprising a desiccant wherein the desiccant has sufficient water affinity to convert the hydrogen sulphide to carbonyl sulphide, wherein the dessicant is selected from the group consisting of an alumina dessicant and a molecular sieve tower. 
   
   
       24 . A method for generating thermodynamic energy from sulphur combustion, the method comprising steps of:
 reducing sulphur dioxide (SO 2 ) by carbonyl sulphide (COS) in the presence of a catalyst to generate carbon dioxide and sulphur vapor (S 2 );   condensing the sulphur vapor (S 2 ) to yield liquid sulphur;   evaporating the liquid sulphur to generate sulphur dioxide (SO 2 ) gas and sulphur vapor (S 2 );   combusting the sulphur vapor (S 2 ) with oxygen gas (O 2 ) to generate hot sulphur dioxide (SO 2 ) gas;   mixing in an ejector the hot sulphur dioxide (SO 2 ) gas with cooler, lower-pressure sulphur dioxide (SO 2 ) gas that is recycled from downstream of at least one turbine; and   harnessing energy in the sulphur dioxide (SO 2 ) gas that emerges from the ejector.   
   
   
       25 . The method as claimed in  claim 24  wherein the carbonyl sulphide (COS) is generated by interacting hydrogen sulphide with carbon dioxide. 
   
   
       26 . The method as claimed in  claim 25  wherein the carbon dioxide is recycled as a product of SO 2  reduction and separated from the sulphur vapor by a condenser that condenses sulphur vapor to liquid sulphur. 
   
   
       27 . The method as claimed in  claim 24  wherein the at least one turbine comprises a gas turbine disposed immediately downstream of the ejector and a steam turbine disposed downstream of the gas turbine. 
   
   
       28 . A method for producing elemental sulphur, the method comprising steps of:
 interacting carbonyl sulphide (COS), sulphur dioxide (SO 2 ), generated by combustion of sulphur vapor (S 2 ) and oxygen (O 2 ) in a combustor/reactor to yield S 2  and CO 2 ;   recovering heat from the S 2  and CO 2  while condensing the S 2  in order to transform the S 2  into liquid sulphur (S 8 ) and elemental sulphur (S); and   extracting the elemental sulphur (S).   
   
   
       29 . The method as claimed in  claim 28  further comprising a step of receiving hydrogen sulphide (H 2 S) into a carbonyl sulphide (COS) generator for generating the COS that is supplied to the combustor/reactor by reacting the hydrogen sulphide (H 2 S) with CO 2  in the COS generator. 
   
   
       30 . The method as claimed in  claim 29  wherein the CO 2  is separated from sulphur vapor and recycled from one or more heat recovery/sulphur condenser units operating downstream of the combustor. 
   
   
       31 . A method for transporting sulphur by pipeline, the method comprising steps of:
 receiving a supply of hydrogen sulphide (H 2 S);   receiving a supply of carbon dioxide (CO 2 );   generating carbonyl sulphide (COS) from the hydrogen sulphide and carbon dioxide;   transporting the COS.   
   
   
       32 . The method as claimed in  claim 31  wherein the supply of carbon dioxide (CO 2 ) is recycled from a reduction reaction of sulphur dioxide (SO 2 ). 
   
   
       33 . The method as claimed in  claim 32  wherein the reduction reaction comprises interaction of sulphur dioxide (SO2) with carbonyl sulphide (COS). 
   
   
       34 . The method as claimed in  claim 31  wherein the supply of carbon dioxide (CO 2 ) is from an external source. 
   
   
       35 . The method as claimed in  claim 31  wherein the step of transporting the COS comprises delivering the COS through a pipeline to a sulphur-recovery plant at a remote location for subsequent recovery of elemental sulphur and energy generation. 
   
   
       36 . The method as claimed in  claim 35  further comprising a step of causing the COS to interact with sulphur dioxide (SO 2 ) in a combustor/reactor disposed within the sulphur-recovery plant at the remote location. 
   
   
       37 . The method as claimed in  claim 36  wherein the sulphur-recovery plant at the remote location comprises a bubbling chamber for supplying sulphur dioxide (SO 2 ) and sulphur vapor (S 2 ) to the combustor/reactor of the sulphur-recovery plant at the remote location, the bubbling chamber receiving liquid S 8  recycled from a heat recovery/sulphur condenser in the sulphur-recovery plant at the remote location that, in turn, receives sulphur vapor (S 2 ) and carbon dioxide (CO 2 ) emerging from the combustor/reactor of the sulphur-recovery plant at the remote location. 
   
   
       38 . A method for generating carbon monoxide, the method comprising steps of:
 interacting in high temperature carbonyl sulphide (COS) with sulphur dioxide (SO 2 ) in presence of carbon dioxide (CO 2 ), in a combustor/reactor to yield S 2 , and carbon monoxide (CO) gas. The sulphur dioxide (SO 2 ) and heat are results of sulphur vapor (S 2 ) combustion in oxygen (O 2 ).   rapidly cooling the S 2 , CO 2  and CO while condensing the S 2  in order to transform the S 2  into liquid sulphur (S 8 ) and elemental sulphur (S), the S 2 , CO 2  and CO being rapidly cooled in order to prevent CO and S 2  re-associating to form COS; and   separating the CO from the remaining CO 2 .   
   
   
       39 . The method as claimed in  claim 38  further comprising a step of generating the COS from an inflow of hydrogen sulphide and carbon dioxide. 
   
   
       40 . The method as claimed in  claim 39  wherein the recycled carbon dioxide is obtained partially from rapidly cooling the S 2 , CO 2  and CO while condensing the S 2  but mainly from external sources. 
   
   
       41 . The method as claimed in  claim 38  further comprising a step of generating sulphur dioxide (SO 2 ) and sulphur vapor (S 2 ) by injecting oxygen (O 2 ) in a bubbling chamber that is furthermore supplied with recycled liquid sulphur (S 8 ) obtained from rapidly cooling the S 2 , CO 2  and CO while condensing the S 2 . 
   
   
       42 . A system for generating power, the system comprising:
 a combustor/reactor for combusting sulphur vapor (S 2 ), and oxygen (O 2 ) to produce sulphur dioxide (SO 2 ) and to reacting the sulphur dioxide (SO 2 ) with carbonyl sulphide (COS) to yield energized gases comprising carbon dioxide (CO 2 ) and sulphur vapor (S 2 );   one or more heat recovery/sulphur condensation units for recovering heat from the energized gases and for generating steam from the heat; and   generating power from the steam.   
   
   
       43 . The system as claimed in  claim 42  further comprising a COS generator for generating COS from a supply of hydrogen sulphide (H 2 S) and a supply of carbon dioxide (CO 2 ). 
   
   
       44 . The system as claimed in  claim 43  wherein the supply of carbon dioxide is obtained as a product of sulphur dioxide reduction by carbonyl sulphide and separated from sulphur vapor by one or more heat recovery/sulphur condensation units that condenses the sulphur vapor to yield elemental sulphur (S), liquid S 8 , the carbon dioxide being fully recycled to regenerate COS by reacting the carbon dioxide with the supply of hydrogen sulphide. 
   
   
       45 . The system as claimed in  claim 44  further comprising a bubbling chamber for receiving oxygen (O 2 ) and recycled liquid S 8  from the one or more heat recovery/sulphur condensation units, and for generating sulphur dioxide (SO 2 ) and sulphur vapor (S 2 ) as a predominant out fluent. 
   
   
       46 . The system as claimed in  claim 45  wherein the sulphur vapor is generated by a bubbling chamber for receiving compressed oxygen (O 2 ) from an oxygen compressor and for receiving recycled liquid S 8 , and for generating the sulphur dioxide (SO 2 ) and sulphur vapor (S 2 ) that are delivered to the combustor/reactor. 
   
   
       47 . The system as claimed in  claim 46  wherein the oxygen compressor is also connected to the combustor/reactor for supplying compressed oxygen to the combustor/reactor. 
   
   
       48 . The system as claimed in  claim 42  wherein the combustor/reactor comprises:
 a combustor for combusting sulphur vapor and oxygen gas; and   an ejector connected downstream to the combustor for receiving hot combustion gases comprising sulphur dioxide and for receiving a supply of cooler carbonyl sulphide (COS) gas, the ejector enabling the hot combustion gases and the cooler carbonyl sulphide gas to exchange heat and pressure, the ejector thereby discharging carbon dioxide and sulphur gases at a temperature below a metallurgic limit of a gas turbine disposed downstream of the ejector, the gas turbine being connected to an oxygen compressor for compressing oxygen that is to be delivered into the combustor.   
   
   
       49 . The system as claimed in  claim 42  wherein the one or more heat recovery/sulfur condensation units comprise:
 a heat recovery steam generator disposed downstream of the gas turbine that drives the oxygen compressor; and   a condenser disposed downstream of the heat recovery steam generator for condensing sulphur vapor into liquid sulphur (S 8 ).   
   
   
       50 . The system as claimed in  claim 49  wherein the condenser is connected to a bubbling chamber for recycling liquid sulphur (S 8 ) into the bubbling chamber wherein the liquid sulphur (S 8 ) reacts with oxygen supplied from the oxygen compressor to form sulphur vapor and sulphur dioxide for delivery into the combustor. 
   
   
       51 . The method as claimed in  claim 43  wherein the carbonyl sulphide is generated in the liquid phase. 
   
   
       52 . The method as claimed in  claim 43  wherein the carbonyl sulphide is generated in the vapor phase. 
   
   
       53 . The method as claimed in  claim 43  wherein the carbonyl sulphide is generated in at least one dryer comprising a desiccant wherein the desiccant has sufficient water affinity to convert the hydrogen sulphide to carbonyl sulphide, wherein the desiccant is selected from the group consisting of a molecular sieve and an alumina desiccant. 
   
   
       54 . A system for combusting sulphur, the system comprising:
 means for combusting sulphur vapor and oxygen gas to produce sulphur dioxide and heat, and for reacting sulphur dioxide with carbonyl sulphide to yield energized gases comprising sulphur vapor and carbon dioxide; and   means for recovering heat and separating carbon dioxide from sulphur vapor by condensing the sulphur vapor to yield steam, elemental sulphur, liquid sulphur and separated carbon dioxide.   
   
   
       55 . The system as claimed in  claim 54  further comprising means for recycling the carbon dioxide for generating carbonyl sulphide. 
   
   
       56 . The system as claimed in  claim 54  further comprising means for generating carbonyl sulphide from a supply of hydrogen sulphide and a supply of carbon dioxide. 
   
   
       57 . The system as claimed in  claim 54  further comprising evaporation means for generating sulphur dioxide and sulphur vapor from oxygen and liquid sulphur, the evaporation means supplying the sulphur dioxide and sulphur vapor to the means for combusting and reacting. 
   
   
       58 . The system as claimed in  claim 54  wherein the means for combusting and reacting comprises a combustor for combusting sulphur vapor and oxygen to produce hot sulphur dioxide gas and an ejector for exchanging heat and pressure between the hot sulphur dioxide gas and a supply of carbonyl sulphide that is delivered into the ejector at a temperature and pressure much lower than a temperature and pressure of the hot sulphur dioxide gas. 
   
   
       59 . The system as claimed in  claim 54  further comprising a means for generating electric power from the steam. 
   
   
       60 . The system as claimed in  claim 54  further comprising a means for extracting elemental sulphur. 
   
   
       61 . The system as claimed in  claim 57  further comprising a means for recycling the liquid sulphur into the evaporation means. 
   
   
       62 . A system for burning sulphur, the system comprising:
 a combustor/reactor for combusting sulphur vapor (S 2 ) and oxygen (O 2 ) to produce sulphur dioxide (SO 2 ) and to reduce the sulphur dioxide by carbon dioxide to yield energized gases comprising carbon dioxide (CO 2 ) and sulphur vapor (S 2 );   an ejector disposed downstream of the combustor/reactor for reducing a temperature and pressure of the hot combustion gases by exchanging heat and pressure with a supply of carbonyl sulphide; and   a carbonyl sulphide generator for generating the carbonyl sulphide supplied to the ejector.   
   
   
       63 . The system as claimed in  claim 62  further comprising one or more heat recovery/sulphur condensation units for recovering heat from the energized gases and for generating steam from the heat. 
   
   
       64 . The system as claimed in  claim 62  further comprising a steam turbine for generating power from the steam. 
   
   
       65 . The system as claimed in  claim 63  wherein the carbon dioxide is recycled from the one or more heat recovery/sulphur condensation units into the carbonyl sulphide generator for reacting with hydrogen sulphide to generate the carbonyl sulphide. 
   
   
       66 . The system as claimed in  claim 62  further comprising a bubbling chamber for generating the sulphur dioxide and sulphur vapor that is supplied to the combustor/reactor. 
   
   
       67 . The system as claimed in  claim 63  further comprising:
 a gas turbine expending downstream of the ejector for driving power generator an oxygen compressor for supplying compressed oxygen to the combustor and to a bubbling chamber that generates sulphur dioxide and sulphur vapor for the combustor/reactor from the compressed oxygen and from a supply of liquid sulphur; and   a steam turbine disposed downstream of the gas turbine for generating power from the steam.   
   
   
       68 . A system for burning sulphur, the system comprising
 a combustor for combusting sulphur vapor (S 2 ) and oxygen (O 2 ) to yield hot combustion gases comprising sulphur dioxide (SO 2 ); and   an ejector disposed downstream of the combustor for reducing a temperature and pressure of the hot combustion gases by exchanging heat and pressure with a supply of recycled sulphur dioxide gas to generate a stream of sulphur dioxide gas at a reduced temperature and pressure, wherein the recycled sulphur dioxide gas is recycled from downstream of at least one turbine that harnesses energy from the stream of sulphur dioxide emerging from the ejector.   
   
   
       69 . The system as claimed in  claim 68  further comprising a bubbling chamber for supplying the sulphur vapor to the combustor, and a condenser for supplying liquid sulphur to the bubbling chamber. 
   
   
       70 . The system as claimed in  claim 69  further comprising a COS generator for generating COS from a supply of hydrogen sulphide and a supply of carbon dioxide, the COS reacting catalytically with sulphur dioxide to yield sulphur vapor that is supplied to the condenser for condensation into the liquid sulphur. 
   
   
       71 . The system as claimed in  claim 70  wherein the at least one turbine comprises a gas turbine disposed immediately downstream of the ejector, a heat recovery steam generator disposed immediately downstream of the gas turbine, and a steam turbine disposed downstream of the heat recovery steam generator. 
   
   
       72 . The method as claimed in  claim 17  wherein the carbonyl sulphide is generated by controlling reaction times during interaction of SO 2  and COS gases at high temperature to thereby produce reaction products of CO and S 2  that are favorable for re-association of CO and sulphur to yield COS in the lower temperature process units. 
   
   
       73 . The method as claimed in  claim 17  wherein the carbonyl sulphide is generated by increasing a concentration of carbon dioxide during interaction of SO 2  and COS gases at high temperature to thereby produce reaction products of CO and S 2  that are favorable for re-association of CO and sulphur to yield COS in the lower temperature process units. 
   
   
       74 . The method as claimed in  claim 1  further comprising a step of enabling re-association of CO and sulphur to yield COS by increasing the carbon dioxide concentration whereby CO and sulphur interact in an excess of carbon dioxide. 
   
   
       75 . The method as clamed in  claim 1  comprising a operating a molecular sieve in an excess of carbon dioxide in order to completely deplete all hydrogen sulphide entering the molecular sieve. 
   
   
       76 . The method as claimed in  claim 42  comprising a molecular sieve that operates in an excess of carbon dioxide in order to completely deplete all hydrogen sulphide entering the molecular sieve. 
   
   
       77 . The method as claimed in  claim 42  wherein the combustor/reactor operates with an increased concentration of carbon dioxide. 
   
   
       78 . The method as claimed in  claim 48  wherein the ejector operates with an increased concentration of carbon dioxide. 
   
   
       79 . The method as claimed in  claim 12  wherein sulphur is evaporated and sulphur vapour oxidized under a pressure in a range of 1 to 35 atmospheres.