AU2011250716A1 - Method For Steam Reforming Carbonaceous Material - Google Patents
Method For Steam Reforming Carbonaceous Material Download PDFInfo
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- AU2011250716A1 AU2011250716A1 AU2011250716A AU2011250716A AU2011250716A1 AU 2011250716 A1 AU2011250716 A1 AU 2011250716A1 AU 2011250716 A AU2011250716 A AU 2011250716A AU 2011250716 A AU2011250716 A AU 2011250716A AU 2011250716 A1 AU2011250716 A1 AU 2011250716A1
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- 238000000629 steam reforming Methods 0.000 title claims abstract description 111
- 238000000034 method Methods 0.000 title claims abstract description 68
- 239000003575 carbonaceous material Substances 0.000 title claims abstract description 47
- 229910052799 carbon Inorganic materials 0.000 claims abstract description 45
- 238000002407 reforming Methods 0.000 claims abstract description 45
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 claims abstract description 41
- 239000000463 material Substances 0.000 claims abstract description 29
- 238000006243 chemical reaction Methods 0.000 claims abstract description 28
- 238000010438 heat treatment Methods 0.000 claims abstract description 23
- 230000015572 biosynthetic process Effects 0.000 claims abstract description 17
- 238000003786 synthesis reaction Methods 0.000 claims abstract description 15
- 239000007769 metal material Substances 0.000 claims abstract description 8
- VNWKTOKETHGBQD-UHFFFAOYSA-N methane Chemical compound C VNWKTOKETHGBQD-UHFFFAOYSA-N 0.000 claims description 30
- 239000007787 solid Substances 0.000 claims description 29
- 239000000446 fuel Substances 0.000 claims description 27
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 20
- 239000002893 slag Substances 0.000 claims description 14
- 235000008733 Citrus aurantifolia Nutrition 0.000 claims description 5
- 235000011941 Tilia x europaea Nutrition 0.000 claims description 5
- 229910052736 halogen Inorganic materials 0.000 claims description 5
- 150000002367 halogens Chemical class 0.000 claims description 5
- 239000004571 lime Substances 0.000 claims description 5
- 230000014759 maintenance of location Effects 0.000 claims description 5
- UIIMBOGNXHQVGW-UHFFFAOYSA-M Sodium bicarbonate Chemical compound [Na+].OC([O-])=O UIIMBOGNXHQVGW-UHFFFAOYSA-M 0.000 claims description 4
- 238000010926 purge Methods 0.000 claims description 3
- 238000007254 oxidation reaction Methods 0.000 claims description 2
- 235000017557 sodium bicarbonate Nutrition 0.000 claims description 2
- 238000001035 drying Methods 0.000 claims 1
- 230000009977 dual effect Effects 0.000 abstract description 9
- 239000011343 solid material Substances 0.000 abstract description 3
- UGFAIRIUMAVXCW-UHFFFAOYSA-N Carbon monoxide Chemical compound [O+]#[C-] UGFAIRIUMAVXCW-UHFFFAOYSA-N 0.000 description 36
- 229910002091 carbon monoxide Inorganic materials 0.000 description 36
- 239000000047 product Substances 0.000 description 19
- 239000010813 municipal solid waste Substances 0.000 description 18
- 239000000428 dust Substances 0.000 description 16
- 229910052751 metal Inorganic materials 0.000 description 13
- 239000002184 metal Substances 0.000 description 13
- 239000007789 gas Substances 0.000 description 12
- 238000002485 combustion reaction Methods 0.000 description 11
- 238000010586 diagram Methods 0.000 description 10
- 239000001257 hydrogen Substances 0.000 description 9
- 229910052739 hydrogen Inorganic materials 0.000 description 9
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 description 8
- UFHFLCQGNIYNRP-UHFFFAOYSA-N Hydrogen Chemical compound [H][H] UFHFLCQGNIYNRP-UHFFFAOYSA-N 0.000 description 7
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 7
- 238000004140 cleaning Methods 0.000 description 7
- 238000000605 extraction Methods 0.000 description 7
- 239000001301 oxygen Substances 0.000 description 7
- 229910052760 oxygen Inorganic materials 0.000 description 7
- 239000002594 sorbent Substances 0.000 description 7
- 239000002699 waste material Substances 0.000 description 7
- 238000004519 manufacturing process Methods 0.000 description 6
- 239000003345 natural gas Substances 0.000 description 6
- 238000000926 separation method Methods 0.000 description 6
- 239000002253 acid Substances 0.000 description 5
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- 238000005498 polishing Methods 0.000 description 5
- 230000009286 beneficial effect Effects 0.000 description 4
- 150000002013 dioxins Chemical class 0.000 description 4
- 150000002240 furans Chemical class 0.000 description 4
- 229910052757 nitrogen Inorganic materials 0.000 description 4
- 231100000614 poison Toxicity 0.000 description 4
- OKKJLVBELUTLKV-UHFFFAOYSA-N Methanol Chemical compound OC OKKJLVBELUTLKV-UHFFFAOYSA-N 0.000 description 3
- 239000006227 byproduct Substances 0.000 description 3
- 238000005516 engineering process Methods 0.000 description 3
- 229930195733 hydrocarbon Natural products 0.000 description 3
- 150000002430 hydrocarbons Chemical class 0.000 description 3
- 150000002431 hydrogen Chemical class 0.000 description 3
- 150000002739 metals Chemical class 0.000 description 3
- 239000000203 mixture Substances 0.000 description 3
- MWUXSHHQAYIFBG-UHFFFAOYSA-N nitrogen oxide Inorganic materials O=[N] MWUXSHHQAYIFBG-UHFFFAOYSA-N 0.000 description 3
- 239000003921 oil Substances 0.000 description 3
- 231100000331 toxic Toxicity 0.000 description 3
- 230000002588 toxic effect Effects 0.000 description 3
- LFQSCWFLJHTTHZ-UHFFFAOYSA-N Ethanol Chemical compound CCO LFQSCWFLJHTTHZ-UHFFFAOYSA-N 0.000 description 2
- GQPLMRYTRLFLPF-UHFFFAOYSA-N Nitrous Oxide Chemical compound [O-][N+]#N GQPLMRYTRLFLPF-UHFFFAOYSA-N 0.000 description 2
- 230000003749 cleanliness Effects 0.000 description 2
- 239000003245 coal Substances 0.000 description 2
- 150000001875 compounds Chemical class 0.000 description 2
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- 230000009466 transformation Effects 0.000 description 2
- 238000011144 upstream manufacturing Methods 0.000 description 2
- OYPRJOBELJOOCE-UHFFFAOYSA-N Calcium Chemical compound [Ca] OYPRJOBELJOOCE-UHFFFAOYSA-N 0.000 description 1
- 239000004215 Carbon black (E152) Substances 0.000 description 1
- BVKZGUZCCUSVTD-UHFFFAOYSA-L Carbonate Chemical compound [O-]C([O-])=O BVKZGUZCCUSVTD-UHFFFAOYSA-L 0.000 description 1
- ZAMOUSCENKQFHK-UHFFFAOYSA-N Chlorine atom Chemical compound [Cl] ZAMOUSCENKQFHK-UHFFFAOYSA-N 0.000 description 1
- PXGOKWXKJXAPGV-UHFFFAOYSA-N Fluorine Chemical compound FF PXGOKWXKJXAPGV-UHFFFAOYSA-N 0.000 description 1
- 239000004698 Polyethylene Substances 0.000 description 1
- 239000004743 Polypropylene Substances 0.000 description 1
- NINIDFKCEFEMDL-UHFFFAOYSA-N Sulfur Chemical compound [S] NINIDFKCEFEMDL-UHFFFAOYSA-N 0.000 description 1
- 239000002154 agricultural waste Substances 0.000 description 1
- 230000033228 biological regulation Effects 0.000 description 1
- 239000011575 calcium Substances 0.000 description 1
- 229910052791 calcium Inorganic materials 0.000 description 1
- BRPQOXSCLDDYGP-UHFFFAOYSA-N calcium oxide Chemical compound [O-2].[Ca+2] BRPQOXSCLDDYGP-UHFFFAOYSA-N 0.000 description 1
- ODINCKMPIJJUCX-UHFFFAOYSA-N calcium oxide Inorganic materials [Ca]=O ODINCKMPIJJUCX-UHFFFAOYSA-N 0.000 description 1
- 239000000292 calcium oxide Substances 0.000 description 1
- 159000000007 calcium salts Chemical class 0.000 description 1
- 239000000460 chlorine Substances 0.000 description 1
- 229910052801 chlorine Inorganic materials 0.000 description 1
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- 238000010276 construction Methods 0.000 description 1
- 238000011038 discontinuous diafiltration by volume reduction Methods 0.000 description 1
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- 239000010793 electronic waste Substances 0.000 description 1
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- 239000003546 flue gas Substances 0.000 description 1
- 239000011737 fluorine Substances 0.000 description 1
- 229910052731 fluorine Inorganic materials 0.000 description 1
- 239000011521 glass Substances 0.000 description 1
- 150000002366 halogen compounds Chemical class 0.000 description 1
- 239000002920 hazardous waste Substances 0.000 description 1
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- 239000010804 inert waste Substances 0.000 description 1
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- 238000010792 warming Methods 0.000 description 1
- 239000002918 waste heat Substances 0.000 description 1
- 239000002916 wood waste Substances 0.000 description 1
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- Hydrogen, Water And Hydrids (AREA)
- Processing Of Solid Wastes (AREA)
Abstract
Abstract A method for steam reforming carbonaceous material into a synthesis gas by using a single stage process of heating the carbonaceous material in a rotary kiln at an elevated reforming temperature so that the carbonaceous material undergoes substantially complete conversion to synthesis gas or by using a dual stream, multiple-stage process of heating carbonaceous material to a reforming temperature, below that at which metallic materials will typically vaporize, to form gaseous and solid materials; further reforming the gaseous materials in a second stage reforming kiln at an elevated reforming temperature to form synthesis gas; and separating carbon char from the solid material for further processing. 3625032_1
Description
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Regulation 3.2 AUSTRALIA PATENTS ACT, 1990 COMPLETE SPECIFICATION FOR A STANDARD PATENT ORIGINAL Name of Applicant: ENQUEST POWER CORPORATION Actual Inventors: ZWIERSCHKE, Jayson; DUECK, Ernest George Address for service in A J PARK, Level 11, 60 Marcus Clarke Street, Canberra ACT Australia: 2601, Australia Invention Title: Method For Steam Reforming Carbonaceous Material The following statement is a full description of this invention, including the best method of performing it known to us. 36241376_1 WO 2006/076801 PCT/CA2006000060 Field of the Invention This invention relates generally to steam reforming technology. 5 Background of the Invention Steam reforming processes are known, and are used for converting various kinds of carbonaceous materials into useful commodities. The term carbonaceous material ("CM") as used herein includes any carbonaceous material, including: municipal solid waste 10 ("MSW"); industrial, commercial and institutional waste ("ICIW'); medical waste; coal; coal waste; wood waste; sawdust; forest product waste; agricultural waste; sewage; liquid waste; hazardous waste; waste oil and oil by-products; electronic waste and other similar carbonaceous substances; also included are opportunity materials such as incineration and/or combustion ash, which may be used in order to achieve conversion upgrade 15 opportunities in existing incineration plants. In the steam reforming process, carbonaceous material is placed in a steam reforming kiln, which usually comprises a dnun or kiln that is rotatable. Typically, the CM includes a substantial level of moisture. The drum is rotated to agitate the wet CM, while being heated. Heat is typically supplied by natural gas burners, syngas burners or electrical 20 induction heating within the kiln, but external to the rotating drum. Steam reforming is an endothermic process. However, unlike incineration, which is exothermic, there is no combustion, Rather, the CM, combined with water, is heated while being agitated, causing a reaction that produces a synthesis gas ("syngas"). The. syngas consists primarily of hydrogen (H2) and carbon-monoxide (CO). 25 A key difference between these two thermal processes is in the respective products generated by these processes. ii the case of incineration/combustion, the products are primarily oxidized noxious compounds, whereas steam reforming produces largely beneficial syngas fuels with some minor acid and metal vapours typically much easier to clean than oxidized products of combustion. 30 Typically, the waste being used as the CM input to the steam reforming process comprises mostly hydrogen and carbon, and a small percentage of other elements such as chlorine, fluorine, sulfur, nitrogen, glass and various metals. For example, municipal solid waste (MSW) typically has a carbon/hydrogen/oxygen ratio of about 1/1.7/0.5. MSW also typically includes about 10% by weight of solid inert products. 1 a WO 20061076801 PCT/CA2006/000060 In a typical prior art steam reforming process, the syngas is produced in a 2-stage process, First, the drum containing the water and CM is heated, typically fbr 90 minutes at temperatures in the range of 650 *C. Then, the solid materials, including metals and char, are extracted from the drum. At this point, about 60-70% of the CM has been steam 5 reformed to produce syngas. The typical process will then "polish" the syngas to convert remaining hydrocarbons to syngas and the pyrolytic char is separated from the remainder of inert inorganics and burned, or the complete mix of char plus other solids is disposed. Summary of the Invention 10 According to the invention, there are two different steam reforming processes, a single stream, one-stage process and a dual stream, multi-stage process. The one-stage process is preferred for situations where the CM has a very small amount of metal in it. This is because the one-stage process described below involves employing temperatures that would vaporize metal. In cases where the amount of metal 15. mixed with the CM is inconsequential, the one stage process is preferred because the amount of any metal vapours will be inconsequential. Where it is not technically feasible to remove substantially all metals mixed into the CM, the multi-stage process described below would/may preferably be used. For both the one-stage process and the multi-stage process, CM, such as municipal 20 solid waste ("MSW") is first shredded. (For the purposes of this description and for ease of reference, the input to the steam reforming process shall be referred to and considered as MSW; however, it should be understood that any CM may be used, and the process can be accordingly adapted for such). Commercial lime (i.e. calcium oxide and/or a bicarbonate of soda) is mixed in with 25 the shredded MSW. When the steam reforming is taking place, the calcium in the lime reacts with halogens that are released from the MSW, forming calcium salts that are generally benign. This feature is important because removing haldgens in this early stage is simpler and less costly than removing them later downstream, which would typically involve using sorbent bed cleaning units. This also avoids the opportunity for these 30 halogens to form acid vapours and/or the more highly toxic dioxins and furans, if these constituents come into contact with oxygen while at elevated temperatures during the steam reforming process. (The formation of dioxins and furans is one of the major problems with most incineration systems). Because the halogens react very readily with the lime, they are not available to form acid vapours and/or dioxins and furans. Note that with steam 2 WO 2006/076801 PCT/CA2006/000060 reforming, where most of the atmospheric air and hence oxygen is purged from the incoming waste stream (as described below), there will be little opportunity for conversions to the toxic dioxins and furans as there most certainly would be for combustion and incineration systems. 5 In both the one-stage and multi-stage processes, the shredded MSW is fed into a hopper, with the hopper containing an auger (i.e. a screw conveyor) for feeding the MSW into the steam reforming kiln. At the entrance into the kiln, the system provides a continuous feed of high temperature steam to purge the MSW entering the kiln of atmospheric air, and in particular, of nitrogen and oxygen. As will be explained further, the 10 additional steam is beneficial to the steam reforming process, since this steam pre-heats the MSW and thereby captures some of the plant process waste heat. Meanwhile, it is also desirable to exclude nitrogen and oxygen to prevent the formation of toxic nitrous oxide and other undesirable nitrogen oxides and/or other oxidized products. As explained above, the typical prior art steam reforming process is a two stage 15 process. The reason for this is that in the first stage, while most of the CM is steam reformed (typically, approximately 60-70% of the amount of starting CM), carbon char is formed, and it has traditionally been believed that this char needs to be removed before the remaining CM can be steam reformed. However, surprisingly and unexpectedly, it has been discovered that the char, if heated sufficiently, can also be steam reformed, and need not be 20 removed. This is beneficial because the steam reforming of the CM is more complete, and because there is less solid waste to dispose of. Therefore, a single stream, one-stage steam reforming process has been designed as follows. The process employs a steam reforming rotary kiln that heats the CM to an elevated reforming temperature, approximately 650*C-1 100 0 C (or higher as may be 25 necessary), with varying residence times to generate substantially the complete conversion of CM into a finished syngas product comprised of primarily H2 and CO. It is contemplated that any conventional steam reforming rotary kiln may be suitable; however, it is preferable (note that it is a specific claim of this invention that the system comprises a single rotating kiln with external heating, since there is a current patent invention that uses a single rotating 30 kiln but uses "internal" combustion heating) that such rotary kiln be externally heated (rather than internally heated), since this reduces the chance that combustion/incineration will take place within the kiln and produce Various noxious side product compounds. The objective in using a one-stage process is to provide sufficient temperature, turbulent mixing and residence time, in a single reaction zone, to achieve target conversion levels. This one 3 WO 2006/076801 PCT/CA2006/000060 stage-steam reforming process may include a polishing unit downstream from the kiln, to further reform the separated, but not completely reformed syngas into a cleaner syngas. The inert solid slag left over in the kiln is then removed prior to polishing of this first stage steam reformed syngas as may be needed. This solid slag is cooled and can be 5 sold as construction filler material. This inert solids extraction will typically represent a volume reduction of up to 98% of the original MSW mix. The system preferably undergoes a dust removal process, in which dust particulate is removed from the reformed syngas. Conventional dust and particle separators/filters are employed, although preferably, this involves a vortical dust separator and a fine particulate 10 filter. This vortical dust separation and removal may take place in the steam reforming rotary kiln. Alternatively, the dust particulates may be removed in similar containers downstream from the reforming rotary kiln. Meanwhile, heat extraction modules will be located downstream of the separator and filter respectively. The heat extractors are used to extract thermal energy from the hot syngas for the use either as direct heat, or for the 15 production of electricity or for pre-heating kiln combustion air and/or preheating feed CM. The next stage of cleaning will preferably comprise sorbent bed or equivalent technologies for removing fugitive acid and metal vapours or other poisons/pollutants to provide for specified syngas cleanliness for subsequent processes. This sorbent bed cleaning system will typically be located downstream of the dust and particulate removal, and will 20 typically be located either upstream or downstream of the heat extraction modules (depending on temperature sensitivities of the sorbent bed materials and temperature dependencies for effective removal of fugitive and poisonous gases). As explained above, the dual stream, multi-stage process is preferably used when there is a larger amount of metallic material in the MSW. It will be appreciated that in most 25 cases, metal is separated out from MSW because of mandatory recycling, and also could be separated by means of metal separation units located on the conveyor feeding shredded MSW into the steam reforming kiln hopper. However, even so, there is often a substantial amount of metal in the MSW which can vaporize during the very high temperature steam reforming process. Also, the multi-stage process is designed to optimize energy 30 consumption by the steam reforming process, as described below: The preferred multi-stage steam reforming process is as follows. There is provided a first stage steam reforming rotary kiln that heats the CM to a reforming temperature of approximately 550"C to 650'C to generate the first phase of syngas production with metallic materials largely intact (i.e. not vaporized) and with residual carbon char. The first - 4 WO 2006/076801 PCTICA2006/000060 stage products are segregated into two streams: a second stage "dusty" gaseous stream; and a third stage solids stream. There is then provided a second stage steam reforming stationary kiln that heats the "dusty" gaseous inflow materials to an elevated reforming temperature of approximately 850*C to I 100*C (or higher as may be necessary) to complete 5 the transformation of first stage gaseous materials by facilitating the complete conversion of carbonaceous gases into a syngas composed primarily of CO and H2. This syngas will typically be rich in hydrogen, since much of the carbon is streamed to the third-stage steam reforming system described below. Note this second stage "stationary" kiln may be configured as a rotary kiln if found necessary to optimize conversion performance of this 10 second stage. Preferably, the process provides for the removal of dust and particulates between the first and second stages. This would typically be done with one or both of vortical dust separators and fine particulate filters. Alternatively, or in addition to this dust removal process, the process will also include the internal separation of dust and particles (entrained 15 in the syngas flow) from the syngas before exiting either the first stage and/or the second and third stage steam reforming kilns. This internal separator will use an internally created strong vortical motion generated by stationary vanes in a converging cylindrical channel. The syngas being drawn- through this exit converging cylindrical tube having integral gas turning vanes will generate the vortical centrifugal forces to allow for separation of particles 20 denser than the syngas being drawn through this exit cylinder. Slots strategically located along the length of the exit cylinder will provide for the egress of particles with the radial momentum imparted by the vortical motion sufficient to separate these particles from the syngas stream exiting the steam reforming kiln. This internal separation device will typically be a cylindrical container, separate from the steam reforming rotating drum. 25 The carbon char is separated from the inert solid slag in the first stage kiln and fed to a third stage steam reforming rotary kiln that heats the residual carbon to an elevated reforming temperature of approximately 850 0 C to 950*C (or higher as may be necessary) to complete the transformation of the carbon char into a syngas composed of virtually equal volumes of CO and H2 according to the steam reforming reaction (with x moles of excess 30 H20):
C+H
2 0+xH 2
O->CO+H
2 +xH 2 0 (1) 5 WO 20061076801 PCT/CA2006/000060 Alternatively, the carbon char may be used directly as heating fuel for either the steam boiler or as heating fuel fr one of the two prior stages of steam reformation, or used directly for product sales. If needed, the outflow from the third stage can be directed to the second stage 5 described above so that the outflow from the third stage can be polished. However, the syngas flowing out of the third stagf is typically substantially cleaner than the first stage syngas and may not require polishing, where carbon char has been effectively separated from remainder of residue. This multi-stage process also preferably includes heat extraction to capture useful 10 energy as the syngas and solids cool. Two heat extraction modules may be staged separately and individually downstream of each of the second and third stages or may be staged downstream of a combined flow of syngas from these separate stages. These heat recovery units can be used to create electrical energy (using steam generation with turbines), or can simply capture the thermal energy used for heating or for pre-heating kiln combustion air 15 and/or preheating feed CM. The multi-stage steam reforming process may optionally include a cleaning unit to perform final cleaning of the syngas using sorbent bed or equivalent technologies for removing fugitive acid and metal vapours or other poisons/pollutants to provide for specified syngas cleanliness for subsequent processes. This sorbent bed cleaning system 20 will typically be located downstream of the dust and particulate removal and will typically be located either upstream or downstream of the heat recovery units (depending on temperature sensitivities of the sorbent bed materials and temperature dependencies for effective removals of fugitive and poisonous gases). It will be appreciated that the steam reforming process produces a syngas 25 comprising H2 and CO. It is desirable to produce a syngas with as high an H 2 /CO ratio as possible. The reason is that H 2 is more valuable as a commodity, and easier to convert to clean energy than is CO. Given global warming considerations, carbon is preferably sequestered rather than released into the atmosphere. This makes the CO more cumbersome to deal with. 30 . There are two methods for maximizing the H 2 /CO ratio. The first is the feeding of excess moisture (above stoichiometric amounts) as an input into the steam reforming process which generates additional H2 and CO 2 in equal abundance. The additional clean
CO
2 can be separated and sequestered. The second method is the feeding of methane 6 WO 2006/076801 PCT/CA2006/000060 (particularly including landfill methane), or other hydrogen-rich materials, including waste oils, as an input into the steam reforming process. Adding excess water and hydrogen rich hydrocarbons to the steam reforming process drives up the proportion of hydrogen relative to the proportion of carbon and 5 oxygen in the steam reforming kiln. This in turn produces a higher H 2 /CO ratio. The principal role of excess water is simply to ensure that there is an adequate supply of steam to complete as close to 100% of the steam reforming as possible.. Any steam reforming conversion of excess water beyond stoichiometric will result in the conversion of CO to
CO
2 plus H2. This creates an improved H2/CO ratio but also creates additional CO 2 . 10 Typically this method of improving the H2/CO ratio will be avoided since it incurs energy penalties and will require additional special processes for sequestering the CO 2 . The advantage of this method of CO 2 sequestering is that the syngas mixture is relatively clean and CO 2 would in this case represent a significant proportion of the syngas and hence allow for an effective separation and sequestering of the CO 2 . 15 Given the usefulness of methane as a steam reforming process input, the invention also preferably contemplates the use of landfill methane. This is convenient, as the steam reforming plant can be built near, adjacent to or directly on a landfill site, which can serve not only as a source of CM, but as a source of landfill methane. There are a number of advantageous uses for the products of the steam reforming 20 processes described above. These are listed below. For example, some or all of the syngas (112 + CO) can be fed into a fuel cell. Fuel cells host an oxidation reaction. In the case of H2 - CO syngas, it is most preferred that a fuel cell such as a liquid carbonate fuel cell or a solid oxide fuel cell be used, because such a fuel cell can act on both 112 and on CO. In respect of H2, the gas is oxidized to produce H 2 0 plus energy. In the case of CO, the fuel 25 cell outputs CO 2 plus energy. The syngas (or a portion thereof) can also be fed into a gas-to-liquid ("GTL") synthesis plant to produce selected synthesized hydrocarbon products, such as methanol, ethanol, polyethylene, polypropylene and equivalents thereof. Excess CO 2 and steam from the GTL, or the CO 2 and steam from the fuel cell, 30 can be channeled into a synergistically located greenhouse. This results in the sequestering of carbon in a manner beneficial to the environment. Meanwhile, the growth of fruit, vegetables, or other agricultural, horticultural or forest products within the greenhouse is enhanced. Also, the CO 2 may be captured and used for other 7 WO 2006/076801 PCT/CA2006/000060 commercial uses or introduced into a conversion process for the production of useful by-products. The hydrogen from the syngas product may simply be extracted and sold or used for desired applications. 5 The CO of the syngas can be fed into a water gas shift reactor, where the following reaction takes place: 1120 + CO + xH 2 0 -+112 + C02 + xH 2 0. Also, the GTL synthesis plant will typically have as an output excess CO not used when the syngas was fed into the plant. This additional CO can also be fed into a water gas shift 10 reactor or can be fed to the fuel cell or sold as a commodity. The H2 from the water gas shift reactor can be fed to a fuel cell as described above, while the C02 is sequestered as described above (by feeding it into a synergistically located greenhouse). Alternatively, the CO and/or the 12 from any one of the above steam reforming processes can be fed to a steam boiler/steam turbine and/or combustion engine for the 15 production of electrical energy. In other words there can be a variety of separate and/or concurrent uses for the CO and 1-12 including GTL conversion, commodity sales, fuel for fuel cells and/or fuel for a gas turbine and/or steam electrical generating unit. The use of a fuel cell as described above requires a constant supply of fuel for that fuel cell. In other words, various problems arise if the supply of fuel is interrupted 20 or intermittent, rather than constant. Because the production of syngas may be interrupted, natural gas, or suitably cleaned landfill gas, can be fed constantly into the fuel cell. Some of this natural gas or landfill gas can be diverted to the steam reforming kiln. Preferably, almost all of the natural gas would be fed into the steam reforming kiln to 25 enhance the hydrogen content of the syngas as described above. However, if the normal syngas production from MSW conversion is interrupted, there will be an automated bypass whereby the natural gas will be routed directly to the fuel cell to maintain the constant fuel supply. Landfill methane can be used instead of natural gas to assure a constant supply 30 of fuel for the fuel cell, with the steam reforming process being located synergistically near or directly on a landfill site. Landfill methane can also be used to heat the steam reforming kiln. A portion of the product syngas itself canbe used to heat one or more of the steam reforming kins.
.
WO 2006/076801 PCT/CA2006/000060 Brief Description of the Drawings Fig. 1 shows a schematic diagram of a preferred embodiment of the present invention. 5 Fig. 2 shows a schematic diagram of the single stream, one-stage process. Fig. 3 shows a schematic diagram of one embodiment of the dual stream, multi-stage process. Fig. 4 shows a schematic diagram of another embodiment of the dual stream, multi stage process. 10 Fig. 5 shows a schematic diagram of another embodiment of the dual stream, multi stage process.
WO 2006/076801 PCT/CA2006/000060 Detailed Description of the Invention Fig. 1 is a schematic diagram of a preferred embodiment of the single stream, one stage process. The CM input 1 is continuously fed into an auger or screw conveyor 2, where it is shredded in a shredder 4. The CM may optionally be pre-treated by passing 5 through a pre-heater or rotary drum dryer 6 before being fed into the steam reforming rotary kiln 9. This serves to do one or more of the following; remove excess moisture from the CM, generate steam, and warm up the shredded CM (to approximately 250*C) in readiness for the steam reforming reaction. Where necessary, make-up water and/or steam 5 is added to the shredded CM. As previously mentioned, it is advantageous to provide for a 10 continuous feed of high temperature steam to purge the CM entering the steam reforming kiln 9 of air, (in particular, of oxygen and nitrogen). The pre-heater 6 is provided with one or more flue gas vents 7 and one or more steam vents 8 for releasing excess steam. The CM is then fed into the steam refonning kiln 9, which is externally heated. Commercial lime 10 is added to the steam reforming kiln so that it will react with any halogen compounds 15 thereby removing such halogens from the CM. The CM is heated within the steam reforming kiln 9 to around 650'C-1 100"C, or higher as necessary depending on the make up of the CM, and undergoes a virtual complete conversion via a steam reforming reaction to reformed syngas 11. The reformed syngas may optionally be further polished, for example by passing it through a vortical dust separator 14 and/or a fine particulate filter 15, 20 to remove dust 16 and fine dust 17, respectively.- The inert solid slag or kiln residue 12 left over after the steam reforming represents approximately 2% by volume of the starting CM input 1. The dust 16 and 17 separated from these polishing units, combined with the kiln residue 12 make up the total residual inert waste 18. The hot, polished syngas may be passed through a heat extraction module 19 which. 25 may be used to create electrical energy (using steam generation with turbines), or simply to capture the thermal energy and reuse it for heating within the system. By way of example, heat extraction modules 19 and 21 maybe used to capture thermal energy for use in the preheater 6 for pre-heating combustion air for the steam reforming rotary kiln 9, thereby improving plant efficiency. The product syngas 20 may be used in a number of different 30 ways as previously described. Fig. 2 is a simplified schematic diagram of the single stream, one-stage steam reforming process of Fig. 1. As shown, the CM input 1 is pre-treated in a pre-heater 6 before being fed into steam reforming rotary kiln 9. The CM is heated in the steam reforming kiln to approximately 650-1 100'C (typically at the higher end of this range), 10 WO 2006/07/6801 PCT/CA2006/000060 where it undergoes a steam reforming reaction. Once the steam reforming process is completed, the reform syngas 11 is passed on for additional polishing and/or cleaning where required. The kiln residue 12 is removed from the steam reforming kiln 9. Fig. 3 is a simplified schematic diagram of one embodiment of the dual stream, 5 multi-stage steam reforming process. The CM input 1 is fed into a first stage steam reforming kiln 25 which heats the CM to approximately 550-650"C. The CM undergoes a first stage steam reforming reaction to form a second stage "dusty" gaseous stream 26 and third stage solids stream 27. At this reforming temperature, the metallic materials within the CM are largely intact (have not vaporized) and remain with the residual carbon char of 10 the solids stream 27. The products of the dusty gaseous stream are passed to a second stage steam reforming stationary ki-In 28, where they are heated to 850-1 100*C (or higher as necessary) to complete the conversion of these gaseous products to syngas 11. The carbon char in the solids stream 27 is separated from the inert solids slag or kiln residue 29. The separated carbon char 30 may be used directly for product sales. 15 Fig. 4 is a simplified schematic diagram of an alternative embodiment of the dual stream, multi-stage steam reforming process shown in Fig. 3. In this application, the separated carbon char 31 is fed into the second stage steam refonning rotary kiln 28a, along with the products of the gaseous stream to undergo steam reforming at an elevated reforming temperature. (The second stage reforming kiln 28a in this application would 20 have to be a rotary kiln, in order to process the solid carbon feed.) Fig. 5 is a simplified schematic diagram of another embodiment of the dual stream, multi-stage steam reforming process shown in Fig. 3. In this application, the separated carbon char 32 is fed into a third stage steam reforming rotary kiln 33 and heated to approximately 850-950*C (or higher as necessary) to complete the reforming of carbon char 25 into syngas 34. (The third stage reforming kiln 33 in this application would have to be a rotary kiln, in order to process the solid carbon feed). The term composingg' as used in this specification and claims means 'consisting at least in part of'. When interpreting statements in this specification and claims which include the term 'comprising', other features besides the features prefaced by this term in each statement can also be present. Related terms such as 'comprise' and 'comprised' are to be interpreted in similar manner. In this specification where reference has been made to patent specifications, other external documents, or other sources of information, this is generally for the purpose of providing a context for discussing the features of the invention. Unless specifically stated otherwise, reference to such external documents is not to be construed as an admission that such documents, or such sources of information, in any jurisdiction, are prior art, or form part of the common general knowledge in the art. 11
Claims (15)
1. A method for steam reforming carbonaceous material into synthesis gas, said method comprising: feeding an input of carbonaceous material into a steam reforming rotary kiln; agitating the carbonaceous material using the steam reforming rotary kiln; heating the carbonaceous material within the rotary kiln to an elevated reforming temperature of from about 65D to 1100*C in the presence of water or steam; reforming the carbonaceous material such that the carbonaceous material undergoes substantially complete conversion via a steam reforming reaction to form synthesis gas and a minimal amount of inert solid slag.
2. The method of claim 1 wherein the steam reforming rotary kiln is externally heated.
3. The method of any one of claim 1 or 2 father comprising the step of preheating or drying the carbonaceous material by passing the carbonaceous material through a preheater before being fed into the steam reforming rotary kiln.
4. The method of claim 1 wherein the carbonaceous material is continuously fed into the steam reforming rotary kiln using an auger or screw conveyor.
5. The method of claim 1 wherein commercial lime and/or a bicarbonate of soda is added to the carbonaceous materials within the steam reforming rotary kiln so as to react with and remove the presence of halogens within the carbonaceous material.
6, The method of any one of claim I or 2 wherein high temperature steam is continuously fed into the base of the rotary kiln feed hopper in order to purge air from the CM being fed via a screw auger into the steam reforming kiln.
7. The method of any one of claim 1 or 2 wherein the water or steam is present in excess (above stoichiometric amounts) sufficient to convert the entire CM into syngas and to maximize the ratio of H 2 /CO in the synthesis gas formed during the steam reaction.
8. The method of any one of claim I or 2 wherein the carbonaceous material is methane. 12 WO 2006/076801 PCT/CA2006/000060
9. The method of any one of claim 1 or 2 wherein the carbonaceous material is landfill methane obtained from a proximate or synergistically located landfill site.
10. A method for steam reforming carbonaceous material, said method comprising: feeding an input of carbonaceous material into a first stage steam reforming rotary kiln; agitating the carbonaceous material using the first stage steam reforming rotary kiln; heating the carbonaceous material within the first stage rotary kiln to a reforming temperature below that -at which metallic materials will vaporize, of from about 550 to 650"C, in the presence of water or steam; reforming the carbonaceous material at the reforming temperature such that the carbonaceous material undergoes a partial conversion via a steam reforming reaction to form a solids stream, consisting of carbon char and inert solid slag, and a gaseous materials stream; feeding the gaseous materials into a second stage steam reforming kiln, heating the gaseous materials stream to an elevated reforming temperature of about 850-1 10O"C in the presence of steam or water; reforming the gaseous materials stream at the elevated reforming temperature such that the gaseous materials stream undergoes a substantially complete conversion via a steam reforming reaction to form synthesis gas; and separating the carbon char from the inert solid slag for direct sales or sequestering of carbon.
11. A method for steam reforming carbonaceous material, said method comprising: feeding an input of carbonaceous material into a fir st stage steam reforming rotary kiln; agitating the carbonaceous material using the first stage steam reforming rotary kiln; heating the carbonaceous material within the first stage rotary kiln to a reforming temperature below that at which metallic materials will vaporize, of from about 550 to 650 0 C, in the presence of water or steam; reforming the carbonaceous material at the reforming temperature such that the carbonaceous material undergoes a partial conversion via a steam reforming reaction to form a solids stream, consisting of carbon char and inert solid slag, and a gaseous materials stream; separating the carbon char from the inert solid slag; feeding the carbon char and the gaseous materials into a second stage steam reforming rotary kiln; heating the gaseous materials stream and clean carbon char to an elevated reforming temperature of about 850-1100*C in the presence of steam or water; and reforming the gaseous materials stream and carbon char at the elevated reforming temperature such that the gaseous materials stream and the carbon char undergo a substantially complete conversion via a steam reforming reaction to form synthesis gas.
12. A method for steam reforming carbonaceous material, said method comprising: 13 WO 2006/076801 PCT/CA2006/000060 feeding an input of carbonaceous material into a first stage steam reforming rotary kiln; agitating the carbonaceous material using the first stage steam reforming rotary kiln; heating the carbonaceous material within the first stage rotary kiln to a reforming temperature below that at which metallic materials will vaporize, of from about 550 to 650"C, in the presence of water or steam; reforming the barbonaceous material at the reforming temperature such that the carbonaceous material undergoes a partial conversion via a steam reforming reaction to form a solids stream, consisting of carbon char and inert solid slag, and a gaseous materials stream; feeding the gaseous materials into a second stage steam reforming kiln; heating the gaseous materials stream to an elevated reforming temperature of about 850-1100 C in the presence of steam or water; reforming the gaseous materials stream at the elevated reforming temperature such that the gaseous materials stream undergoes a substantially complete conversion via a steam reforming reaction to form syngas; separating the carbon char from the inert solid slag; feeding the clean carbon char into a third stage steam reforming rotary kiln; heating the carbon char to an elevated reforming temperature of about 8 50-11 00*C in the presence of steam or water; and reforming the carbon char at the elevated reforming temperature such that the carbon char undergoes a substantially complete conversion via a steam reforming reaction to form synthesis gas.
13. A method for steam reforming carbonaceous material, said method comprising: feeding an input of carbonaceous material into a first stage steam reforming rotary kiln; agitating the carbonaceous material using the first stage steam reforming rotary kiln; heating the carbonaceous material within the first stage rotary kiln to a reforming temperature below that at which metallic materials will vaporize, of from about 550 to 650 0 C, in the presence of water or steam; reforming the carbonaceous material at the reforming temperature such that the carbonaceous material undergoes a partial conversion via. a steam reforming reaction to form a solids stream, consisting of carbon char and inert solid slag, and a gaseous materials stream; feeding the gaseous materials into a second stage steam reforming kiln, heating the gaseous materials stream to an elevated reforming temperature of about 850-11001C in the presence of steam or water; reforming the gaseous materials stream at the elevated reforming temperature such that the gaseous materials stream undergoes a substantially complete conversion via a steam reforming reaction to form synthesis gas; separating the carbon char from the inert solid slag and using the carbon char as a fuel for heating one or both of the one stage and two-stage steam reforming kilns. 14 WO 2006/076801 PCT/CA20061000060
14. The method of any of claim 1, 2, 10, 11, 12 or 13, comprising the further step of feeding the synthesis gas into a fuel cell, which can host an oxidation reaction of the synthesis gas to form H20 and/or CO 2 .
15. The method of claim 14 wherein carbon may be sequestered by feeding any excess CO 2 into a synergistically located greenhouse. 15
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| AU2011250716A AU2011250716B2 (en) | 2005-01-18 | 2011-11-11 | Method For Steam Reforming Carbonaceous Material |
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| US60/644,601 | 2005-01-18 | ||
| AU2006207788A AU2006207788A1 (en) | 2005-01-18 | 2006-01-18 | Method for steam reforming carbonaceous material |
| AU2011250716A AU2011250716B2 (en) | 2005-01-18 | 2011-11-11 | Method For Steam Reforming Carbonaceous Material |
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