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  • C01B3/00—Hydrogen; Gaseous mixtures containing hydrogen; Separation of hydrogen from mixtures containing it; Purification of hydrogen
  • C01B3/02—Production of hydrogen or of gaseous mixtures containing a substantial proportion of hydrogen
  • C01B3/32—Production of hydrogen or of gaseous mixtures containing a substantial proportion of hydrogen by reaction of gaseous or liquid organic compounds with gasifying agents, e.g. water, carbon dioxide, air
  • C01B3/34—Production of hydrogen or of gaseous mixtures containing a substantial proportion of hydrogen by reaction of gaseous or liquid organic compounds with gasifying agents, e.g. water, carbon dioxide, air by reaction of hydrocarbons with gasifying agents
  • C01B3/38—Production of hydrogen or of gaseous mixtures containing a substantial proportion of hydrogen by reaction of gaseous or liquid organic compounds with gasifying agents, e.g. water, carbon dioxide, air by reaction of hydrocarbons with gasifying agents using catalysts
  • C01B3/382—Multi-step processes
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01F—MIXING, e.g. DISSOLVING, EMULSIFYING OR DISPERSING
  • B01F23/00—Mixing according to the phases to be mixed, e.g. dispersing or emulsifying
  • B01F23/20—Mixing gases with liquids
  • B01F23/21—Mixing gases with liquids by introducing liquids into gaseous media
  • B01F23/213—Mixing gases with liquids by introducing liquids into gaseous media by spraying or atomising of the liquids
  • B01F23/2132—Mixing gases with liquids by introducing liquids into gaseous media by spraying or atomising of the liquids using nozzles
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  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
  • B01J8/00—Chemical or physical processes in general, conducted in the presence of fluids and solid particles; Apparatus for such processes
  • B01J8/02—Chemical or physical processes in general, conducted in the presence of fluids and solid particles; Apparatus for such processes with stationary particles, e.g. in fixed beds
  • B01J8/0207—Chemical or physical processes in general, conducted in the presence of fluids and solid particles; Apparatus for such processes with stationary particles, e.g. in fixed beds the fluid flow within the bed being predominantly horizontal
  • B01J8/0214—Chemical or physical processes in general, conducted in the presence of fluids and solid particles; Apparatus for such processes with stationary particles, e.g. in fixed beds the fluid flow within the bed being predominantly horizontal in a cylindrical annular shaped bed
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  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
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  • B01J8/02—Chemical or physical processes in general, conducted in the presence of fluids and solid particles; Apparatus for such processes with stationary particles, e.g. in fixed beds
  • B01J8/0207—Chemical or physical processes in general, conducted in the presence of fluids and solid particles; Apparatus for such processes with stationary particles, e.g. in fixed beds the fluid flow within the bed being predominantly horizontal
  • B01J8/0221—Chemical or physical processes in general, conducted in the presence of fluids and solid particles; Apparatus for such processes with stationary particles, e.g. in fixed beds the fluid flow within the bed being predominantly horizontal in a cylindrical shaped bed
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  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
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  • B01J8/00—Chemical or physical processes in general, conducted in the presence of fluids and solid particles; Apparatus for such processes
  • B01J8/02—Chemical or physical processes in general, conducted in the presence of fluids and solid particles; Apparatus for such processes with stationary particles, e.g. in fixed beds
  • B01J8/0278—Feeding reactive fluids
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  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
  • B01J8/00—Chemical or physical processes in general, conducted in the presence of fluids and solid particles; Apparatus for such processes
  • B01J8/02—Chemical or physical processes in general, conducted in the presence of fluids and solid particles; Apparatus for such processes with stationary particles, e.g. in fixed beds
  • B01J8/0285—Heating or cooling the reactor
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
  • B01J8/00—Chemical or physical processes in general, conducted in the presence of fluids and solid particles; Apparatus for such processes
  • B01J8/02—Chemical or physical processes in general, conducted in the presence of fluids and solid particles; Apparatus for such processes with stationary particles, e.g. in fixed beds
  • B01J8/04—Chemical or physical processes in general, conducted in the presence of fluids and solid particles; Apparatus for such processes with stationary particles, e.g. in fixed beds the fluid passing successively through two or more beds
  • B01J8/0403—Chemical or physical processes in general, conducted in the presence of fluids and solid particles; Apparatus for such processes with stationary particles, e.g. in fixed beds the fluid passing successively through two or more beds the fluid flow within the beds being predominantly horizontal
  • B01J8/0423—Chemical or physical processes in general, conducted in the presence of fluids and solid particles; Apparatus for such processes with stationary particles, e.g. in fixed beds the fluid passing successively through two or more beds the fluid flow within the beds being predominantly horizontal through two or more otherwise shaped beds
  • B01J8/0426—Chemical or physical processes in general, conducted in the presence of fluids and solid particles; Apparatus for such processes with stationary particles, e.g. in fixed beds the fluid passing successively through two or more beds the fluid flow within the beds being predominantly horizontal through two or more otherwise shaped beds the beds being superimposed one above the other
  • B01J8/043—Chemical or physical processes in general, conducted in the presence of fluids and solid particles; Apparatus for such processes with stationary particles, e.g. in fixed beds the fluid passing successively through two or more beds the fluid flow within the beds being predominantly horizontal through two or more otherwise shaped beds the beds being superimposed one above the other in combination with one cylindrical annular shaped bed
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  • C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
  • C01B3/00—Hydrogen; Gaseous mixtures containing hydrogen; Separation of hydrogen from mixtures containing it; Purification of hydrogen
  • C01B3/02—Production of hydrogen or of gaseous mixtures containing a substantial proportion of hydrogen
  • C01B3/32—Production of hydrogen or of gaseous mixtures containing a substantial proportion of hydrogen by reaction of gaseous or liquid organic compounds with gasifying agents, e.g. water, carbon dioxide, air
  • C01B3/34—Production of hydrogen or of gaseous mixtures containing a substantial proportion of hydrogen by reaction of gaseous or liquid organic compounds with gasifying agents, e.g. water, carbon dioxide, air by reaction of hydrocarbons with gasifying agents
  • C01B3/38—Production of hydrogen or of gaseous mixtures containing a substantial proportion of hydrogen by reaction of gaseous or liquid organic compounds with gasifying agents, e.g. water, carbon dioxide, air by reaction of hydrocarbons with gasifying agents using catalysts
  • C01B3/386—Catalytic partial combustion
• • B—PERFORMING OPERATIONS; TRANSPORTING
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  • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
  • B01J2208/00—Processes carried out in the presence of solid particles; Reactors therefor
  • B01J2208/00008—Controlling the process
  • B01J2208/00017—Controlling the temperature
  • B01J2208/00106—Controlling the temperature by indirect heat exchange
  • B01J2208/00168—Controlling the temperature by indirect heat exchange with heat exchange elements outside the bed of solid particles
  • B01J2208/00203—Coils
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
  • B01J2208/00—Processes carried out in the presence of solid particles; Reactors therefor
  • B01J2208/00008—Controlling the process
  • B01J2208/00017—Controlling the temperature
  • B01J2208/0053—Controlling multiple zones along the direction of flow, e.g. pre-heating and after-cooling
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
  • B01J2208/00—Processes carried out in the presence of solid particles; Reactors therefor
  • B01J2208/00008—Controlling the process
  • B01J2208/00628—Controlling the composition of the reactive mixture
  • B01J2208/00646—Means for starting up the reaction
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
  • B01J2208/00—Processes carried out in the presence of solid particles; Reactors therefor
  • B01J2208/00008—Controlling the process
  • B01J2208/00716—Means for reactor start-up
• • C—CHEMISTRY; METALLURGY
  • C01—INORGANIC CHEMISTRY
  • C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
  • C01B2203/00—Integrated processes for the production of hydrogen or synthesis gas
  • C01B2203/02—Processes for making hydrogen or synthesis gas
  • C01B2203/0205—Processes for making hydrogen or synthesis gas containing a reforming step
  • C01B2203/0227—Processes for making hydrogen or synthesis gas containing a reforming step containing a catalytic reforming step
  • C01B2203/0244—Processes for making hydrogen or synthesis gas containing a reforming step containing a catalytic reforming step the reforming step being an autothermal reforming step, e.g. secondary reforming processes
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  • C01B2203/00—Integrated processes for the production of hydrogen or synthesis gas
  • C01B2203/02—Processes for making hydrogen or synthesis gas
  • C01B2203/025—Processes for making hydrogen or synthesis gas containing a partial oxidation step
  • C01B2203/0261—Processes for making hydrogen or synthesis gas containing a partial oxidation step containing a catalytic partial oxidation step [CPO]
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  • C01B2203/00—Integrated processes for the production of hydrogen or synthesis gas
  • C01B2203/04—Integrated processes for the production of hydrogen or synthesis gas containing a purification step for the hydrogen or the synthesis gas
  • C01B2203/0455—Purification by non-catalytic desulfurisation
• • C—CHEMISTRY; METALLURGY
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  • C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
  • C01B2203/00—Integrated processes for the production of hydrogen or synthesis gas
  • C01B2203/04—Integrated processes for the production of hydrogen or synthesis gas containing a purification step for the hydrogen or the synthesis gas
  • C01B2203/0465—Composition of the impurity
  • C01B2203/0485—Composition of the impurity the impurity being a sulfur compound
• • C—CHEMISTRY; METALLURGY
  • C01—INORGANIC CHEMISTRY
  • C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
  • C01B2203/00—Integrated processes for the production of hydrogen or synthesis gas
  • C01B2203/08—Methods of heating or cooling
  • C01B2203/0872—Methods of cooling
  • C01B2203/0888—Methods of cooling by evaporation of a fluid
  • C01B2203/0894—Generation of steam
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  • C01—INORGANIC CHEMISTRY
  • C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
  • C01B2203/00—Integrated processes for the production of hydrogen or synthesis gas
  • C01B2203/12—Feeding the process for making hydrogen or synthesis gas
  • C01B2203/1276—Mixing of different feed components

Definitions

• the present invention is directed to a method and system for the process of reactively converting a liquid fuel into a gasified stream. More particularly, the method and system of the present invention provide a novel means for converting the liquid fuel into a gas by partial oxidation and steam reforming. In addition, when fuels containing sulfur are used, a device according the present invention can be employed to provide de-sulfurization.
• Gasification of liquid fuels typically comprises use of a vaporizer.
• Vaporization of liquid fuels typically is achieved by indirectly supplying heat into a stream of liquid fuel via heat exchange with a hot wall.
• One disadvantage of this method is that the rate of vaporization is limited by the rate of heat transfer such that relatively large surface area is required for fuel vaporization.
• Another disadvantage of this method, especially for vaporizing long chain hydrocarbons is that heating the fuel stream to the vaporization temperature tends to cause fuel decomposition and formation of deposits. More specifically, coke formation is problematic.
• preventing deposits from forming within the fuel passages in the nozzle during steady state operation due to heat-up of the nozzle from the downstream hot zone is challenging.
• Another known method for gasification of a fuel stream comprises mixing atomized fuel with a hot gas such as superheated steam that supplies the heat required for fuel vaporization and prevents coke formation.
• a hot gas such as superheated steam that supplies the heat required for fuel vaporization and prevents coke formation.
• superheated steam that supplies the heat required for fuel vaporization and prevents coke formation.
• the large amounts of superheated steam required in this method result in a large heat load for steam production.
• Spray methods for atomization of liquid fuels known in the art include air-blast or pressure atomizers, ultrasonic and electrospray atomizers. These spray systems are capable of providing a uniform distribution of atomized fuel across the entrance of the catalyst bed. Such atomizers may include a co-flow of air that allows mixing of the fuel and oxidizer. However, very fine and uniform droplet size along with homogeneous fuel-air distribution, required to avoid coke formation and obtain temperature/mixture uniformity in the reactor, is difficult to achieve in practical systems.
• Ignition devices such as a spark or glow plugs, are widely used to ignite fuel- oxidizer mixtures at startup. These devices often are subject to failure due to the high operating temperatures by virtue of their location required for ignition.
• Monoliths are commonly used catalyst substrates for the gasification of liquid fuel. Fuel oxidizer mixture inhomogeneities are usually detrimental to these substrates as they lead to localized lean or rich zones respectively causing hot spots or carbon precipitation regions. Since there is no opportunity for these zones to re-mix within the long, separated channels of a monolith, these substrates are particularly vulnerable. In addition, carbon precipitation is favored in monoliths due to the boundary layers that develop in these substrates.
• Liquid hydrocarbon fuels such as gasoline, kerosene or diesel may be used with high temperature solid oxide fuel cells ("SOFC") to directly produce electric power.
• SOFC solid oxide fuel cells
• the choice of fuel is not limited to pure hydrogen as is the case for low temperature proton exchange membrane (“PEM”) fuel cells.
• Conversion of the hydrocarbon fuel into gaseous mixture containing syngas, though, is required before the fuel may be fed to the SOFC. Furthermore, removal of sulfur normally contained in the fuel prior to feeding to the SOFC is needed.
• a catalyst substrate that facilitates mixing of the stream flowing therethrough, for example a substrate having plurality of voids in random order and short channels extending in the downstream direction the length of which is similar to the channel diameter.
• the system of the present invention eliminates the need for a liquid fuel vaporizer in a typical gasification system.
• a liquid fuel vaporizer By eliminating the vaporizer, an essential and critical part of the reforming systems known in the art, the entire system is less complex and more robust. Vaporizing hydrocarbon fuels is difficult because of low decomposition temperature of these fuels which leads to coke deposits and clogging of the fuel delivery lines. Spraying cold fuel directly into the catalyst bed eliminates this problem.
• a heat exchanger is positioned downstream of the catalyst bed thereby utilizing the heat generated in the reforming reaction to produce steam required for the system while cooling the reformate stream to the temperature required by the downstream components, i.e. de-sulfurization bed.
• a de-sulfurization bed is positioned downstream of the catalyst bed.
• de-sulfurization is achieved by de-sulfurization of the fuel in the liquid form in a hydro-de-sulfurization (“HDS”) process prior to the reforming process.
• HDS hydro-de-sulfurization
• the present invention is a system for converting liquid fuels into gas mixture containing CO and H2 (syngas).
• the system is comprised of: (i) a nozzle; (ii) a catalyst bed in fluid communication with the nozzle exhaust stream; (iii) a heat source for igniting the catalyst; and (iv) a heat exchanger.
• the hot side of the heat exchange is in fluid communication with the catalyst bed and the cold side of the heat exchanger in fluid communication with the nozzle.
• Atomized liquid fuel is exits the nozzle in a stream comprising an oxidizer and optional steam. In most applications, oxygen as a constituent of air is a preferred oxidizer.
• the ratio of the fuel stream to the oxidizer stream should be such that there is insufficient amount of oxidizer to completely oxidize all fuel into CO2 and H2O, i.e. the ratio should be fuel rich.
• the fuel entering the nozzle is cold (i.e., below the temperature at which the fuel starts to decompose creating coke deposits).
• the nozzle design is such that the liquid fuel remains cold before exiting the nozzle. This is an important point distinguishing this invention from previous methods, for example US Patent No. 4,381,187.
• the nozzle may be of any type (i.e., based on pressure atomization, air blast, ultrasonic atomization, electrospray, or other type known in the art).
• the nozzle provides fine atomization of cold liquid fuel and uniform distribution of the atomized fuel within the inlet air or optionally steam containing inlet air.
• the catalyst bed comprises catalyst suitable for supporting partial oxidation and reforming reactions.
• the catalyst is one of the metals of group VIII of the periodic system of elements, preferably, rhodium.
• the substrate on which the catalyst is supported preferably provides good mixing for the fuel/oxidizer mixture passing therethrough.
• the substrate preferably comprises a multiplicity of void volumes in random order. This may be best achieved by using porous metal or ceramic substrates or by using multiple ceramic or metal screens or foams.
• the preferred catalyst bed geometry provides a decreasing mass flux of the reactive mixture flow through the catalyst bed as disclosed in U.S. Patent Application No. 10/324,464 filed December 19, 2002; the contents of which are incorporated herein in its entirety, particularly the teachings at Paragraphs 0014-0031 including Figures 1 and 2.
• Preferred catalyst formulations could be used on different parts of the coil.
• MicrolithTM short-contact-time, ultra-short-channel-length substrate is available from Precision Combustion, Inc., 410 Sackett Point Road, North Haven, Connecticut..
• the nozzle and the catalyst bed are arranged in such a way that the stream of atomized fuel mixed with air and steam provided by the nozzle is uniformly distributed across the entry face of the catalyst bed. It is preferred that the rate of flow of the reacting mixture through the catalyst bed is sufficiently high such that significant amounts of partial oxidation products (i.e., CO and H2) are formed. When partial oxidation products are formed, less heat is released thereby resulting in lower temperatures of the catalyst bed.
• partial oxidation products i.e., CO and H2
• the heat/ignition source is placed in closed proximity with the catalyst bed. It is required for the initial pre-heat of the catalyst to the temperature where the oxidation reaction between the fuel and the oxidant would ignite.
• the heat source may be of any type known in the art.
• An electrically heated glow plug is a preferred heat source.
• the heat exchanger downstream of the catalyst bed can be any type of a heat exchanger known in the art.
• the heat exchanger should be placed such that the gaseous reformate flow exiting the catalyst bed passes on the hot side the heat exchanger.
• the heat exchanger then cools the reformate flow to the required temperature.
• the heat exchanger vaporizes cold liquid water to produce steam which is fed to the nozzle outlet.
• a sulfur removal bed may be placed in fluid communication with the heat exchanger.
• the cooled reformate stream containing sulfur in the form OfH 2 S exiting the heat exchanger passes through the sulfur removal bed to provide a sulfur free reformate stream.
• the method and system of the present invention provide gasification of liquid fuel without a requirement for supplying external heat or steam to the gasifier.
• Fuel and air may be supplied to the gasifier at ambient temperatures. This allows a smaller mixing volume, since the catalytic bed tolerates partial unmixedness, and a simpler fuel and air delivery system design. This also allows a means for start up and operation in the absence of initial heat at the reactor inlet. More importantly, the method and system of the present invention provide a means for the gasification of a liquid fuel without the use of an external vaporizer.
• FIG. 1 depicts a schematic representation of an embodiment of a gasification system.
• FIG. 2 depicts a schematic representation of another embodiment of a gasification system according.
• FIG. 3 depicts a diagrammatic representation of a detailed design of a gasification system according to the present invention.
• Fig. 4a and 4b provide a three-dimensional rendering of a detailed design of a gasification system according to the present invention.
• Fig. 5 provides a graphical representation of lightoff temperature versus time in a gasification system according to the present invention.
• Fig. 6 provides a graphical representation of the dependence of fuel conversion on the air-to-fuel ratio in a gasification system according to the present invention.
• FIG. 7 provides a schematic flow diagram of a gasification system according to the present invention.
• a typical gasification system 10 comprises a path (12) defining a flow of air (14).
• Fuel stream (16) is introduced into injector (18), which atomizes fuel stream (16).
• Atomized fuel (20) and air (14) enter catalyst bed (22) where fuel (20) is additionally mixed, vaporized and partially reformed.
• Gasified fuel stream (24) leaves the catalyst bed (22).
• Ignition source (26) in close proximity with catalyst bed (22), is used to initiate the process.
• Fig. 2 schematically depicts alternative gasification system (110). Functional elements corresponding to those depicted in Fig. 1 are referenced by corresponding 100- series reference numbers.
• catalyst bed (122) defines a cylindrical shape and comprises a wound catalytically coated, short-contact-time, ultra-short-channel-length substrate.
• Atomized fuel (120) and airflow (114) enter into the inner diameter (128) of catalyst bed (122) and flow out radially (130) through catalyst bed (122).
• the igniter (126) in this embodiment comprises an electric glow plug (132) placed inside inner diameter (128) of catalyst bed (122). Glow plug (132) may be coated with catalyst (134) to further assist the start up process.
• Electric current initially is supplied to glow plug (132) to preheat catalyst bed (122) to the start up temperature.
• Fuel stream (116) is introduced into injector (118), and air (114) is then mixed with atomized fuel (120) causing catalyst bed (122) to heat up to the operating temperature at which point the electric current to the glow plug (132) is stopped.
• Gasified fuel stream (124) exits the system (110).
• Fig. 3 depicts a diagrammatic representation of a design of a gasification system (200) according to the present invention for converting liquid fuels into gas mixture containing CO and H2 (syngas).
• the system (200) is comprised of a nozzle (202) having an inlet (204) and an outlet (206).
• a cold fuel liquid stream (208) and an inlet oxidizer stream (210) are introduced into the inlet (204) (which inlet may have more than one orifice).
• a nozzle exhaust stream (212) comprising atomized liquid fuel mixed with oxidizer and, if desired, steam exits nozzle (202) at outlet (206).
• Catalyst bed (214) is in fluid communication with the nozzle exhaust stream (212).
• the system (200) further comprises a heat source (216) for igniting the catalyst bed (214).
• a heat exchanger (218) is in fluid communication with, or placed in close proximity with, the catalyst bed (214) and the nozzle (202).
• Atomized liquid fuel exits the nozzle (202) in exhaust stream (212) which further comprises an oxidizer and optional steam.
• exhaust stream (212) which further comprises an oxidizer and optional steam.
• oxygen as a constituent of air is a preferred oxidizer.
• the ratio of the fuel stream to the oxidizer stream should be such that there is insufficient amount of oxidizer to completely oxidize all fuel into CO 2 and H 2 O, (i.e., the ratio should be fuel rich).
• Exhaust stream (212) is uniformly distributed across the entry face of the catalyst bed (214).
• the reactive mixture comprising exhaust stream (212) is introduced in the ID plenum of the catalyst bed (214) and the reformed gas exits at the OD of the catalyst bed (214) coil.
• the heat/ignition source (216) is placed in closed proximity with the catalyst bed (214) in order to pre-heat the catalyst bed (214) to the temperature where the oxidation reaction between the fuel and the oxidant ignite.
• Gaseous reformate flow exits the catalyst bed (214) in fluid communication with a first side (220) of heat exchanger (218).
• the gaseous reformate is then cooled to the required temperature by passing through, or in close proximity with, heat exchanger (218).
• the second side (222) of heat exchanger (218) vaporizes cold liquid water stream (224) to produce steam (226), which is fed to the inlet (204) of nozzle (202).
• a sulfur removal bed (228) may be placed in fluid communication with the first side (220) of heat exchanger (218).
• the cooled reformate stream containing sulfur in the form Of H 2 S exiting the heat exchanger (218) passes through the sulfur removal bed (228) to provide a sulfur free reformate stream.
• Fig. 4a and 4b provide a three-dimensional rendering of detailed design of a gasification system (300) according to the present invention.
• An Auto Thermal Reforming (ATR) reactor comprised a coiled catalyst bed, a fuel atomization nozzle and a start up glow plug.
• the reactor comprises the core of the reforming system, which system is further incorporated into a system comprising a heat exchanger/steam generator, ZnO de- sulfurization bed and fuel, air and water pump.
• the ATR was enclosed in a quartz housing to enable visual observation of the catalyst temperature uniformity.
• the reactor was also equipped with eight thermocouples for studying temperature distribution within the catalyst bed.
• Gasification system (300) is an embodiment of gasification system (200) described hereinabove and some of the features are called out using similar characteristics numbers for descriptive and illustrative purposes.
• Fig. 4a depicts the system (300), catalyst bed (314), heat/ignition source (316), and heat exchanger (318). Fig. 4a also depicts, among other features described hereinabove with reference to Fig. 3, cold fuel liquid stream inlet (308), oxidizer stream inlet (310), and liquid water stream inlet (324).
• the glow plug permits the reactor to lightoff at ambient conditions.
• 12 V DC potential is applied to the glow plug providing heat directly to the catalyst. This results in catalyst temperature increasing to above lightoff temperature in about 30 seconds.
• Fuel flow is then started resulting in the reactor lightoff and transition to operational state in about 1 minute.
• the glow plug is shut off and steam flow to the reactor is started. This causes temperature decrease on the front of the catalyst bed, such that more air can be added to the reactor and complete fuel conversion achieved. Reactor temperatures during the lightoff process are shown in Figure 5.
• ASPEN ® modeling was used to examine and determine the system layout including sensitivities to water addition/recycle/recapture and their associated impacts.
• the system configuration is illustrated in Figure 7.
• the system operates at approximately 1 - 2 atm.
• the ATR feed water is delivered to a heat exchanger where it is vaporized prior to mixing with air supplied at the same pressure.
• the steam/air mix is combined with hydrocarbon fuel (represented by dodecane) through a nozzle, prior to delivery to the ATR.
• the ATR is represented as an adiabatic reactor yielding an equilibrium product distribution.
• the hot ATR product serves as the heat source for vaporizing the feed water. This is a benefit because it allows low temperature valving to be used to control the reformate flows.
• the feed O/C ratio was fixed and two convergence criteria were imposed on the simulation. The first required that the temperature of the steam exiting the heat exchanger was sufficient to achieve a specified ATR mixed feed temperature (300 C - 400 C). The second required that the temperature of the cooled ATR product leaving the heat exchanger be compatible with effective sulfur removal in a downstream ZnO bed (typically 300 - 350 C). This was controlled by regulating the water feed rate. Thus, for a given O/C, the S/C ratio was that value which simultaneously satisfied these two requirements. Case studies showed that there was a preferred O/C range (-1.1 - 1.2) below which target ATR feed temperatures could not be achieved and above which system efficiencies declined excessively. As an example, at a fixed O/C of 1.2, acceptable operation for a 400 C target
• ATR feed temperature and a 300 C ATR product temperature exiting the heat exchanger could be obtained at a feed S/C of 2.16.
• the resultant LHV based thermal efficiency for these conditions was -75% for the reforming system (including BOP parasitics but not including fuel-cell efficiency). Without a fuel cell, heat integration was relaxed in the system prototype. Integration of heat and water-recovery from the downstream SOFC will be required when operating with the stack.

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