FR2531944A1 - HYDROCARBON FUEL REFORMING APPARATUS IN A HYDROGEN-RICH GAS - Google Patents

Abstract

THE INVENTION RELATES TO A FUEL REFORMING APPARATUS INCLUDING SEVERAL TUBES 4 FILLED WITH A CATALYST HEATED AT HIGH TEMPERATURE FROM THE EXTERIOR FOR TRANSFORMING THE FUEL 12 INTO GAS 17 CONTAINING HYDROGEN AS A MAIN CONSTITUENT. THE PROBLEM SOLVED IS TO IMPROVE OPERATION BY REDUCING CONSTRUCTION AND MAINTENANCE COSTS. THE APPARATUS IS CHARACTERIZED IN THAT THE TUBES FILLED WITH CATALYST 4 ARE ARRANGED IN A FLUIDIZED BED 24. THE INVENTION IS APPLICABLE IN PARTICULAR TO THE PRODUCTION OF GAS INTENDED FOR FUEL CELLS AND FOR THE OBTAINING OF MOTOR FORCE.

Description

"Hydrocarbon fuel reforming apparatus

into a gas rich in hydrogen ".

  The subject of the invention is a fuel reforming apparatus of the type comprising several tubes

  filled with catalyst arranged to be heated at room temperature.

  increased by external heating, so as to transform

  by reforming, the gas fuel containing hydro-

  gene as the main constituent, this co-carrier passing through each of the catalyst-filled tubes

  The expression reforming apparatus

  fuel means an apparatus for converting a hydrocarbon fuel to a hydrogen-containing gas as the main constituent A large number of fuel reforming apparatus of the type mentioned above has

  have been installed so far in chemical plants.

  To facilitate understanding of the

  In this invention, it is useful to briefly describe a device

  of fuel reforming currently known.

  FIG. 1 schematically represents an apparatus

  conventional fuel reforming reactor The most widely used fuel reforming apparatus is a steam reforming apparatus in which the reforming of the fuel is carried out by means of the steps in which steam is added to a fuel such as CH, or sinilary, the mixture of coffee and steam is passed through a high temperature catalyst layer, for example comrred between 750 and 900 ° C to transform it by reforming into a gas containing hydrogen as a main constituent , the residual carbon monoxide is converted into Co 2 using a CO converter and the CO 2 is removed to obtain

  a high purity of the gas containing hydrogen.

  Specifically, a fuel such as

  CH 4 or the like provided from a food source

  tion located outside the fuel reforming plant shown in FIG. 1 is first desulphurized in a desulphurization apparatus 1 and then added to it with 2-vapor 2, so that the mixture of fuel and

  steam is sent in a series of tubes 4 filled with

  catalyst, these tubes being arranged in a reforming furnace

  3 The tubes 4 filled with catalyst are heated

  at a high temperature between 750 and 900 ° C by the radiant heat emitted by the surfaces of the walls of the steam reforming furnace 3, these surfaces being heated

  by operating multiple burners 5 When the

  The mixture of fuel and steam passes through a

  catalyst in each of the tubes 4 filled with cat-

  lyser, it undergoes a reforming transforming it into a gas con-

  Holding hydrogen The reforming gas 6 containing hydrogen as a main constituent is subjected to heat exchange in a heating tube 7, wherein the heat exchange takes place between the reforming gas 6 and

  water 2 'which is sent to the heating tube 7 from u-

  source of supply located outside the

  combustion reforming plant The gas is then

  produced in a CO 8 converter in which the residual carbon monoxide is transformed into CO 2 After leaving the CO 8 converter, the reforming gas enters a CO 2 absorption tower 9 in which the residual carbon dioxide This results in the removal of high purity hydrogen from the fuel reforming plant. On the other hand, the combustion gases 11 from the steam reforming furnace 3 are subjected to heat exchange in the reactor. a heat exchange part 7 'in which the heat exchange is carried out between the combustion gases 11 and the steam 2 produced in the heating tube 7 The gases

  are then discharged into the outside atmosphere.

  However, it has been found that the apparatus of

  conventional fuel reforming, constructed as described above

  It has the following drawbacks: 1) The tubes 4 filled with catalyst of the steam reforming furnace are subjected to a very high temperature and the heat-resistant metallic material which constitutes them thus functions necessarily in For this reason, they tend to break when subjected to any locally increased thermal load or uneven temperature distribution.

  This results in a gas leak. We are therefore obliged to

  see the steam reforming furnace with a significantly reduced thermal load and to ensure that the heat load is evenly distributed over the furnace, this one is built with larger dimensions and a large number of burners mounted on the walls. Consequently, the reforming furnace

  conventional steam is expensive to manufacture and it is necessary to

  space for his installation.

  2) After leaving the tubes 4 filled with catalyst the combustion gases are usually subjected

  heat exchange in a heat exchanger where the exchange of heat

  is done between the flue gases and the water (steam) but no heat recovery is performed in the lower temperature zone of the outlet duct. The conventional steam reforming furnace therefore operates with a low

thermal efficiency.

  3) To ensure that the oven operates with a reduced heat load and evenly distributed

  in its extent, catalyst-filled tubes are usually

  indirectly heated by the heating walls

  furnace coated with refractory material, these walls being heated

  by means of several burners To protect the material

  refractory, it is necessary to reduce the speed of variation

  when the oven is in operation

  This means that it takes a long time to

  the oven is put into operation or stopped.

  4) The minimum charge is usually about 50%.

  greatly reduced and only with great difficulty.

  ) Since the conventional steam reforming furnace is designed for pressure conditions

  normal operation, it is built with larger

  In addition, because it is in depression, it is necessary to mount a blower type

induction.

  Accordingly, the present invention has

  made with the following disadvantages in mind:

  top of the conventional fuel reforming apparatus and is intended to create a fuel reforming apparatus

  perfected with excellent performance characteristics.

  slow and can be manufactured at a reduced price -

  For this purpose, the invention relates to a

  fuel reforming fluid of the above type characterized in that the catalyst-filled tubes are arranged in

a fluidized bed.

  The essential advantages of the apparatus of

  reforming of fuel according to the invention are the following

  : 1) It is built with smaller dimensions, the space required for its installation is reduced

  as much as possible and its operation is economical.

  2) Heat recovery from gases

  burned actually takes place and so it works with a

high thermal insulation.

  3) It can be put into operation or

  stopped in a very short period of time.

  4) It can work with a heat load

significantly reduced.

  To achieve the purpose mentioned above, -

  a variety of research and development work was done.

  Following this research and development, it was found that the goal could be satisfactorily achieved.

  using a fluidized bed system for the apparatus of

  a plurality of catalyst filled tubes being arranged in the fluidized bed so as to allow their heating from this bed, an air heater being further mounted in the zone of low temperatures in the conduit through which flow. the burnt gases from the steam reforming furnace, this air heater serving as a heat exchanger in which the heat exchange is carried out between the combustion gases and the combustion air to recover

the heat of these gases.

  According to one embodiment, the invention relates to an improved fuel reforming apparatus

  of the type comprising several tubes filled with catalyst

  to be heated at high temperature from the outside

  in order to reformulate the fuel

  gas containing hydrogen as the main constituent

  pal, this fuel passing through each of the tubes filled with catalyst, the improvement that the tubes

  filled with catalyst are arranged in a fluidized bed.

  In addition, following another method of

  The invention relates to a fuel reforming apparatus

  improved type of the above type in which the perfection-

  The fact is that the tubes filled with catalyst are

  arranged in a fluidized bed and that a heat exchanger

  is mounted at a predetermined location, a heat exchange taking place in this exchanger between combustion gases

  outgoing and incoming combustion air.

  In addition, following another method of

  The invention relates to a fuel reforming apparatus

  perfected the above type, in which the perfection-

  The fact is that the tubes filled with catalyst are

  arranged in a fluidized bed and in that a

  recycling cycle in which a portion of the pressure is recycled

  combustion gases taken from an exhaust duct.

  In addition, following another method of

  The invention relates to a fuel reforming apparatus

  perfected the above type, in which the perfection-

  It consists in that the tubes filled with catalyst are.

  arranged in a fluidized bed consisting of a fluid material

  said to be non-combustible, with several straight burners being

  arranged above the floor of the fluidized bed.

  In addition, following another method of

  The invention relates to a fuel reforming apparatus

  improved type of the type above, in which the perfection-

  It is important that the catalyst-filled tubes are respectively designed as double-walled tubes.

  Moreover, according to another mode of

  The invention relates to a fuel reforming apparatus

  improved type of the above type in which the perfection-

  The fluidized bed is formed in the form of a fluidized bed operating under pressure, a gas turbine being installed at a predetermined location and being

  controlled by the flue gases.

  The invention will now be described in more detail with reference to the accompanying drawings in which:

  FIG. 1 schematically represents an ap-

  the same for conventional fuel reforming;

  FIG. 2 diagrammatically represents a first

  first embodiment of the fuel reforming apparatus

tible according to the invention;

  FIG. 3 diagrammatically represents one

  x example embodiment of the apparatus for reforming

bustible according to the invention;

  FIG. 4 schematically represents a third

  second example of embodiment of the apparatus for reforming

  bustible according to the invention; FIG. 5 and FIG. 5b are planar views

  steam reforming furnace furnace

  ming of conventional fuel; Figure 6 is a plan view in section of a steam reforming furnace of the fuel reforming apparatus according to the invention;

  FIG. 7 is a side view of the

  fuel reforming fuel in vertical section along line I-I of FIG. 2;

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  7 - schematically shows a fourth embodiment of the fuel reforming apparatus according to the invention; Fig. 9 is a partial vertical sectional view schematically showing the arrangement of plural straight burners in the fluidized bed of the fuel reforming apparatus according to the present invention; Fig. 10 is a partial plan view

  schematically showing the arrangement of the conventional burners

  tilines relative to several tubes filled with catalyst in the fluidized layer; Fig 11a schematically shows the preliminary mixing mode of fuel and combustion air before entering a straight burner; Fig lb shows schematically the need for a perforated distribution plate for the conventional fluidized bed; Fig 12a is a vertical sectional view of a fuel reforming apparatus according to a fifth embodiment of the invention, the section being taken along the line B-B of Fig 12 b; Fig. 12b is a cross-sectional view of the fuel reforming apparatus, the section being taken along line A-A of Fig. 12a; Fig. 13a is a vertical sectional view of a double-walled tube 3 filled with catalyst and used in the fuel reforming apparatus according to the invention;

  FIG. 13b is a cross sectional view of

  salted double catalyst-filled paroil tube, the section being taken along the line C-C of Fig 13a;

  Fig. 13c is a cross sectional view of

  dirty double-walled tube filled with catalyst, the section being taken along the line D-D of Fig 13a; FIG. 14 is a graph showing schematically the distribution of the temperature on the tube 8

4 2531944

  double wall filled with catalyst shown in Figs. 13a to 13c and for the fuel reforming apparatus Fig. 15 schematically shows a sixth embodiment of the fuel reforming apparatus according to the invention. It will begin with, describe the first embodiment of the invention with reference to FIG. 2. In the drawings, reference numeral 3 denotes a steam reforming furnace. Numeral 12 denotes a fuel tube extending horizontally above the reforming furnace at the

  steam 3 to bring the fuel into several tubes 4

  Catalyst plies Numeral 13 denotes a mixer located at a location in the middle of the fuel tube 12, so as to mix the fuel with steam La

  reference numeral 14 designates a steam supply pipe extending

  between the mixer 13 and a steam heater 27 for

  connect them to bring a stream of steam into the fuel.

  In addition, reference numeral 15 designates

  an inlet manifold disposed before the tubes 4 filled with cata-

  lyser, so as to connect the fuel tube to these tubes 4 to distribute the mixture of fuel and steam between these

  4 tubes filled with catalyst, this collector being disposed

  steam reforming oven top 3 -

  Numeral 4 denotes a series of catalyst-filled tubes 4, each of which is arranged vertically in a fluidized bed 24 disposed in the steam reforming furnace 3.

  outlet manifold arranged after the tubes 4 filled with cat-

  lyser for collecting the reforming gas containing hydrogen as a main component, this gas from the tubes 4 after completion of the reforming reaction The collector

  16 is disposed below the steam reforming furnace 3.

  Reference numeral 17 denotes a reforming gas tube starting from the collector 16 for conveying the reforming gas

  out of the reforming facility.

9 2531944

  Reference numeral 18 designates a

  fan blower arranged outside the refor-

  The reference numeral 19 designates an air heater mounted at a location downstream of the blower 18 and in the middle of the air duct. 20 for heating the combustion air by heat exchange between the combustion air and the exhausted hot gases The numeral 20 denotes an air duct through which the fan

  blower 18 is connected to the heater 19 and by which this

  deny is in turn connected to the air chamber 21 of the burner dis-

  placed on the outside of the steam reforming oven 3

  numeral 5 designates a burner mounted on the wall la-

  steam reforming furnace 3 and the numerical reference

  21 indicates an air chamber of this burner in which the combustion air is collected and stored before entry

in the burner 5.

  Reference numeral 22 designates a distribution

  air scorer disposed at the bottom of the steam reforming oven 3 In this air manifold 22 flows upwardly through a large number of orifices therein, the air being uniformly distributed. The numeral 23 designates an air chamber disposed beneath the air distributor 22 in the vapor reforming furnace 3. The fluid port 24 defines a fluidized fluid for heating a fluidized bed. series of tubes 4 filled with catalyst and a steam heater 27 disposed in the steam reforming furnace 3

  open area in the steam reforming oven 3.

  Reference numeral 26 designates a collection

  feed water inlet manifold in which the water to be heated is fed This feed water inlet manifold 26 is connected to a heating tube 7 disposed within the steam reforming furnace -3 The reference numeral 7 designates a

  tube disposed in the outlet portion of the furnace

2531944

  steam forming 3 for generating steam Numeral 27 designates a steam heater extending vertically in the area between the side wall

  of the steam reforming furnace 3 o are mounted the burner 5 -

  and the tubes 4 filled with catalyst, so as to heat the

  steam produced in the heating tube 7.

  In addition, the reference numeral 28 designates

  an exhaust duct through which the flues of the furnace

  steam forming 3 are connected to the air heater 19 for

  send the combustion gases into it The numerical reference

  29 designates a chimney disposed downstream of the heater

  19 to send the combustion gases into the atmosphere.

  The fuel reforming apparatus con-

  truit as described above works as indicated above.

after.

  Fuel brought from a source

  fuel supply located outside the facility.

  The fuel reforming process passes into the fuel

  12 and enters the mixer 13 where it is mixed with the steam supplied by the steam supply tube 14 The mixture of

  fuel and steam is then sent to the collector

  located above the tubes 4 filled with catalyst,

  so that it is evenly distributed among them when-

  the mixture flows down inside each of the tu-

  2 $ the 4 fill it di-cat-lyseur, it is cha'-f 4 at high temperature

  by heat transfer from the fluidized bed 24.

  The mixture-is thus broken down by

  by producing a reforming gas containing hydrogen

  The gas thus produced containing hydrogen as a

  principal constituent, is collected at the exit of the collection.

  16 is located below the catalyst-filled tubes 4. The gas is then transported further to the treatment with the catalyst.

  the reforming gas transport tube 17.

  On the other hand, the combustion air to be supplied to the burner 5 is first compressed by the fan

- * 531944

1 1 9

  blowing 18-; it is then reheated in the heater 19 o takes place a heat exchange between the pressurized air and the combustion gases The air thus heated is sent to the

  air chamber 21 of the burner via the air duct 20 to ensure

  the combustion of the fuel sent to the burner

  pressurized air enters the air chamber 23 and

  flowing upwards by fluidizing the material disposed in the combustion chamber forms a fluidized bed 24 The flue gas enters the rear flue passing through the unobstructed portion above the fluidized bed

  24 These gases then heat the water flowing into the heating tube.

  phantom 7 from the inlet water inlet manifold 26.

  These gases then flow into the heater 19 passing through the exhaust duct 28 After the completion of the heat exchange with the combustion air in the air heater, the combustion gases are discharged into the exhaust pipe. atmosphere by the

  chimney 19 Water and / or heated steam in the heating tube

  phantom 7 flow into the vapor heater 27 in which the water is completely vaporized The vapor thus produced

: is sent to the mixer 13.

  FIG. 3 schematically represents an apparatus

  reforming fuel according to a second example of

  Embodiment of the Invention In this exemplary embodiment, a steam reforming oven ept divided into two fluidized beds.

  24, that is to say in an upper fluidized bed and in a fluid bed.

  Said lower, both designated by 24 With this arrangement can be reduced significantly the space required to install the apparatus It follows that this embodiment is preferably used in cases where the installation must be

  performed in a strictly limited space.

  FIG. 4 schematically represents an apparatus

  In this exemplary embodiment, a recycle gas sampling duct 30 is connected to the exhaust duct 28 at a location upstream of the fuel recovery duct 28 according to a third exemplary embodiment of the invention.

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  12- air heater 19 and a fan 31 for blowing recycle gas is disposed on the conduit 30 for sampling

  recycle gas to put the gases: recycling under pressure.

  Further, a recycle gas delivery conduit 32 is disposed between the recycle gas ventilator 31 and the air chamber 23, so that the combustion gases are recycled through the fluidized bed via the recirculation conduit 30. sampling

  recycle gas and the return gas conduit 32.

  cycling, while these gases are pressurized by means of

blower 31.

  Thus, in the apparatus of reforming of com-

  bible constructed as described above, a portion of the combustion gases is withdrawn through the conduit 30 for sampling recycle gas, these gases being introduced into the air chamber

  through the blower 31 gas blowing recycling

  In these conditions, a fluidized bed 24 is established in the same way.

  that in the preceding examples of embodiment the apparatus con-

  form of this embodiment has the characteristic advantage

* that the conditions for establishing the fluidized bed 24 can

  can be determined separately from those for combustion air. It is clear that fluidization can be performed,

  using the mixture of flue gas and

  cycling. The distinguishing features and advantages of the apparatus of the invention will be described in more detail below.

  reforming fuel according to the invention.

  1) An essential advantageous feature of the invention is that several catalyst-filled tubes are heated at elevated temperature using a fluidized bed. The most important feature of the fluidized bed is that it is

  ensures excellent effective contact between fluid

  as well as between the fluidized materials and the fluid (combustion gas).

  uniform temperature due to the thermal conduction velocity

13 '"Z 2531944

  High risk between the fluidized material and the fluid (combustion gas)

  regardless of the importance of the temperature difference.

  in the fluidized bed. As a result, the tubes 4 replace

  catalyst folds are heated in a temperature

  The steam reforming furnace can be designed with a compact structure. Since the fluidized bed has a thermal conductivity coefficient that is several times greater than that of normal gas, it is safe we can

  greatly reduce the required heat conduction area.

  Fig. 5a and Fig. 5b are plan and sectional views of conventional steam reforming furnaces installed in a chemical plant where reforming is carried out

  of a fuel Figure 5a shows schematically the

  With a uniform spacing of a line of tubes 4 filled with catalyst Fig 5b shows two lines of tubes filled with

  zigzag catalysts, since the tubes 4 replace

  catalyst plies are designed to be heated by the thermal energy radiated by the inner wall of the reforming furnace

  steamed 3 coated with refractory material, the furnace

  ming classic does not have a uniform charge in thermal energy with a uniform temperature distribution in the volume

  inside of the reforming furnace As Figs 5 a and 5b show

  very well, only a relatively small number

  of tubes filled with catalyst inside the reforming furnace

  ming. On the other hand, FIG. 6 is a plan view and

  section of a steam reforming furnace constructed in accordance with

  As can be seen from FIG. 6, the fuel reforming apparatus according to the invention is designed so that a series of tubes 4 filled with catalyst is heated in

  fluidized bed with a uniform temperature distribution in the reforming apparatus.

  have a number of tubes 4 filled with catalyst greater than in the case of the conventional apparatus, these tubes being 14 - placed with a very small distance between neighboring tubes,

  so that the whole device is designed with a lower

  dimensions Smaller space is needed to

  the apparatus, while each of the catalyst filled tubes 4 has a reduced heat conduction surface due to the high thermal conductivity coefficient which

is guaranteed.

  2) In the case of the conventional fuel reforming apparatus, it is necessary that the surface of the steam reforming furnace wall functions both as an insulating material to stop the heat emission

  to the outside atmosphere and as a heat accumulator

  for storing radiant heat for heating

  Catalyst-filled tubes This leads to increasing the thickness of

  of the refractory material constituting the furnace wall.

  However, there is a risk of damage, cracks or damage.

  similar maggots in the refractory layer because of

  of thermal stress if the furnace is subjected to a velocity of

  Therefore, to ensure that the refractory material constituting the surface of the wall

  is adequately protected, it is necessary to reduce

  as much as possible the rate of change of temperature.

  It follows that the start-up and shutdown of the fuel reforming apparatus can only be

L 5 lon; ae period 2 of time.

  On the other hand, the apparatus of reforming

  according to the invention is constructed so that a large

  number of catalyst filled tubes are heated by means of

  temperature from the fluidized bed.

  that the surface of the reforming furnace wall functions as an insulating material to stop the emission of heat to the external atmosphere. Thus, the refractory material constituting the surface of the wall is suitably protected

  against damage, cracks or similar inde-

  the importance of the speed of temperature variation

  This means that we can predict a speed of variation

  high temperature It should be noted that it is possible to

  see an extremely high rate of temperature variation in the furnace wall when this wall-is made with

  several inner water tubes, so as to cool it.

  S It is then possible to reduce as much as possible the time required to start or stop the appliance 3) To ensure that the reforming oven

  steam is uniformly charged with thermal energy, the

  conventional fuel reformer should have a large number of burners on the wall surface

  against, in the fuel reforming apparatus following the n-

  As a result, a fluidized bed is used to heat a series of catalyst-filled tubes so that the reforming furnace is uniformly loaded with thermal energy. As a result of this arrangement of the furnace, the burners are designed to heat only the fluidized materials. In practice, a small number of burners having a high combustion capacity are mounted on the surface of the reforming furnace wall. The number of burners to be mounted can therefore be greatly reduced compared to the conventional apparatus. Since steam heating tubes are arranged between the burners and the catalyst-filled tubes, there is no risk that a combustion flame from the burners will reach the tubes directly.

  filled with catalyst, even if these burners produce a flam-

  me excessively elongated due to abnormal combustion.

  Thus, no local overheating occurs due to the existence of

  areas called "hot spots".

  4) Since heat recovery actually takes place, by heat exchange between the flue gases that exit and the combustion air that arrives, in

  the part of the flue gas discharge where these are

  slow at low temperature, the device has a thermal efficiency

overall high.

  ) Fig. 7 is a vertical sectional view

  schematic of the apparatus along the line I-I of FIG.

  16- As seen in the drawings, the reforming furnace at the

  Steam 3 is divided into four chambers, so that the function

  the oven can easily take place under

  Fig. 7 shows in particular that, among others.

  the four rooms, only the room on the right is in operation (that is to say, it is in the so-called bed condition

  active), the other rooms not being in operation W (that is,

  to say that they are in the so-called bed condition).

  This means that the oven operates under a load equal to 25% of the full load It is also possible to do so

  operate under a load substantially equal to 15%

  suitably the operating conditions.

  6) Since the fuel reforming apparatus according to the invention is constructed in such a way that a portion of the combustion gases is used as a fuel gas.

  fluidization for the fluidized bed by means of the steps in the

  it is extracted from the exhaust pipe, pressurized with a blower and

  flow through the fluidized bed in the form of recycle gas

  ge, it is possible to operate the device with a name

  more degrees of freedom than in the case of the conventional apparatus. Referring to FIG. 8, a com-uring reforming apparatus will now be described in accordance with FIG.

  fourth embodiment of the invention.

  In this figure, the reference numeral 51

  designates a water supply pipe through which feed water

  It is noted that the water supply is carried out in accordance with

  a volume of steam (H 20) necessary for reforming the fuel

  A portion of the water contained in the flask 52 is sent to lower manifolds 54 by means of a down tube 53 while the water flows upward into a series of tubes 57, 58 from the manifold. lower 54, these tubes 57, 58 extending along the inner peripheral wall of the oven 17 - and partitions, it is transformed into a mixture of water and steam with the aid of the fluidized materials 76 serving as agent of thermal conduction by which the heat produced by

  rectilinear burners 60 is transmitted to the tubes 57,58.

  mixture of water and steam returns to the vapor balloon 52

  through upper collectors 55 and upper tubes

56.

  On the other hand, steam from the steam drum 52 is superheated in a superheater 63 Steam

  overheated is then sent to a blender.

  bustible and vapor 62 through an outlet manifold

  64 of the superheater The mixer 62 is connected to a fan tube

  fuel 61 by which a fuel (e.g.

CH 4) is fed to the mixer.

  The mixture of fuel and steam is introduced into a heater 66 through an inlet manifold 65 of the heater, so as to be heated to a predetermined temperature in this heater 66. The mixture is then fed into a large number of elements. reforming

  cylinders 69 filled with> catalyst passing through a col-

  67 outlet reader of the heater and collectors 68 of

  The result is that the fuel (CH 4) contained in the mixture is converted by reforming into the required carbon containing CH 2) and the oxide.

of carbon (CO).

  A catalyst based on vanadium and nickel

  is used as a typical catalyst in this apparatus.

  The lyser is normally made with a cylindrical shape

  an inner diameter of between 5 and 6 mm, an outside diameter of 16 mm and a height of 19 mmi The reforming gas

  is extracted from the apparatus through collectors of

  The reforming gas is thus used as a raw material for fuel cells, the production

  driving force and similar applications.

  In Fig. 8, reference numeral 72 designates an air heater disposed on the highest end portion of the apparatus. Air flows into this air heater 72 through a supply duct. of combustion air 71 while it is still at a low temperature The air of com-

  The heated mixture is then sent to a pre-blender.

  liminal 78 fuel and air through a conduit

  hot air outlet 73 and a hot air inlet duct 74.

  On the other hand, the exhaust gases from a thermal power station are judiciously mixed with

  fuel (CH 4) in a predetermined proportion and the mixture

  The exhaust gas and fuel gas are introduced into the mixer 78 through a fuel feed tube 59 in which it is mixed with the combustion air from the air heater 72. air is sent to burners 60 to allow combustion in

these burners.

  The heat produced by the combustion of the mixture using the burners 60 is used as an agent.

  for heating the reforming elements 69 to preheat

  fluidized material (sand or similar material) for

  reforming the mixture of fuel and -

  steam, get the required product This heat is also

  used as a heating agent to produce heat

  Because the combusting gases are still hot, generally at a temperature above 800 GC, even after the heat has been used in the reforming elements 69 disposed in the fluidized bed, they are used again as a source. heat for heating the heater 66 for mixing fuel and steam to heat the steam superheater 63 and the combustion air heater

  72 The combustion gases are then discharged out of the

  In the drawing, the reference numeral designates a floor on which fluidized materials are

retained.

  The distinguishing features and advantages of the fuel reforming apparatus constructed as previously described are given below; (1) Sand or similar non-combustible material is used as a fluidized material. Thus, more degrees of freedom are available in selecting the type of fuel for heating the reforming elements. If the fluidized material were combustible, it would be impossible to bring a

  low amount of fuel as auxiliary fuel

  and the fluidized material would be limited to solid fuels

  such as coal and similar fuels However, in the apparatus according to the invention, a non-combustible fluidized material is used and it is then possible to determine as necessary, its type, the size of its grains as well as

other characteristics.

  2) As shown in FIG. 9 and FIG. 10, several straight burners 60 are arranged in the fluidized bed which comprises a large number of reforming elements 69 (in a position located close to the floor). By this arrangement, it is possible to obtain the following advantageous features: (i) The fluidized material is uniformly heated; (ii) A large number of

  low capacity burners with uniform spacing

  interior of the fluidized bed in the minimum space required, which ensures uniform heating; (iii) As shown in FIG. 11a, the straight burner 60 is designed as a premix burner in which the mixture of the fuel F and the air of

  A combustion is prepared in a fuel tube or

  As a result of using a large number of straight burners 60 in the fluidized bed,

  it is not necessary to provide a perforated plate P (usually

  placed at the base of the fluidized bed) which also serves as

2531944.

  - distribution plate, this perforated plate allowing the air

  A flow up in the fluidized bed as

on fig 11 b.

  (iv) -As the straight burners

  are located above the floor at a certain distance

  of it, we are sure that the floor is well protected.

  The present invention has been described above with reference to a fuel reforming apparatus but it should not be limited to such apparatus and may be applied to a fluidized bed type heat exchanger or

a similar device.

  We will describe in the following a fifth and

  a sixth embodiment of the invention.

  In the fifth embodiment of the present invention, a large number of catalyst-filled tubes are heated at elevated temperature in a fluidized bed while the maximum operating temperature of the heating source is kept below a predetermined value. With a uniform temperature distribution in the fluidized bed The catalyst filled tubes are arranged in the form of double-walled tubes, so as to allow recovery.

  effective heat exchanger A heat exchanger arranged externally

  the reforming facility can be built with

  minimun dimensions, the thesis of the installation

significantly increased.

  On the other hand, in the sixth embodiment of the invention, a large number of tubes filled with

  catalyst are heated at elevated temperature in a fluid bed.

  said under pressure, while the operating temperature

  of the heating source is maintained above

  under a predetermined value with a temperature distribution

  uniform bedding in the fluidized bed Tubes filled with

  lyser are arranged in the form of double-walled tubes,

  to enable effective heat recovery.

  Apparently the device is built with smaller dimen-

  As a result of this arrangement, each of the catalyst-filled tubes is made with a small wall thickness, so as to reduce the thermal stress and to ensure a reduced weight and economical manufacture. a series of modules, can be carried out using a trailer or similar vehicle To use the residual heat contained in the flue gases more efficiently after they have left the fluidized bed which serves

  of heating agent, a gas turbine is mounted in a location.

  located outside the fuel reforming plant, this gas turbine being controlled by the gases

burned from the appliance.

  Fig 12a and Fig 12b show schematic

  In the drawings, reference numeral 81 designates a fluidized bed established by fluidization of granular material such as sand, alumina, or the like.

  similar (whose grain size is usually

  between 40 and 200 microns).

  an outer tube constituting a double-walled tube,

  catalyst fold and the reference numeral 83 designates a

  The reference numeral 84 denotes an open space above the fluidized bed and the reference

  nlimér; This figure designates the exit cord as coiubfustion gas.

  The reference numeral 86 designates an air chamber for combustion air A sent to the fluidized bed. The reference numeral 87 denotes a gas chamber for the gas G 1 sent to the catalyst-filled tubes. The reference numeral 88 denotes an inner tube constituting Catalyst-filled double-walled tube 89 denotes a reforming gas outlet tube G 2 and numeral 90 denotes a reforming gas outlet manifold.

  digital 91 designates an output duct; reform gas

  The reference numeral 92 designates a series of burners arranged at a distance from one another in the fluidized bed.

  burners 92 being arranged in the form of rectilinear burners.

22 2531944

  22-Figures 13a to 13c show in detail the structure of a double-walled tube filled with catalyst, the

  FIG. 13a is a vertical sectional view of the tube filled with

  13 b being a cross-sectional view along the line C-C of FIG. 13a and FIG. 13c being another cross-sectional view along the line D-D of FIG.

  drawings, numeral 82 designates an outer tube

  the double walled catalyst-filled tube

  and reference numeral 88 designates an inner tube constituting

  The catalyst 93 may also be disposed in an annular volume defined by the outer tube 82 and the inner tube 88. As a typical catalyst, a vanadium-nickel catalyst is preferably used. Typical of this catalyst is that of a tube having an inner diameter of between 5 and 6 μm, an outside diameter of 16 mm and a height of 19 min. The numeral 94 designates a porous retainer plate.

  catalyst or a screen plate fitted to the tube

  The reference numeral 95 designates a guide fin-located on the upper end portion of the double-walled tube and numeral 96 denotes a helical ribbon disposed inside the inner tube so as to promote the transmission of heat. 97 denotes

  a support plate on which the outer tube is closed

  mounted in vertical direction The reference number 98

  designates another support plate on which the tube

  is firmly mounted in the same direction as the outer tube. We will now describe how

  and the distinctive features of the refor-

  ming of fuel built as previously described.

  Referring again to FIG. 12, the air A supplied to the combustion air chamber 86 provides combustion of the fuel leaving the burners 92. The combustion gases thus produced flow upwards as

  flow by establishing a fluidized bed 81 within the

  The heat produced is thus effectively

  transmitted to a large number of tubes 82 filled with cat-

  the temperature distribution corresponding to a time

  constant temperature in the fluidized bed 81 -

  As is apparent from the drawings, the

  It is such that the fluidized bed 81 is established below the plane near the upper end of the tubes 82.

  The result is that the surface of the

  cross-section increases sharply in the volume released

  located above the fluidized bed 81, so that the speed

  In this way it is possible to reduce as much as possible the so-called driving phenomenon, this driving phenomenon being a malfunction such that the fluidized material is entrained with the updraft. This means that the supply of additional material for the bed

  fluidized is reduced as much as possible.

  lines 92 are arranged at the bottom of the fluidized bed 81, so as to allow it to take effect after a short period of time by reducing as much as possible the temperature difference distributed on the fluidized bed La let-,

  Reference numeral G 3 denotes the combustion gases.

  In accordance with FIGS. 13a to 13c which represent

  feel in detail the internal structure of the double-walled catalyst-filled tube, the annular volume defined between the tube

  82 and the inner tube 88 is filled with the catalyst

  93 Gas G 1, which constitutes the raw material before

  The reforming is flown upward as a rising stream through the gas inlet pipe while the raw material gas flows upwardly through the catalyst layer. is transmitted to the outer tube 88 from the fluidized bed 81, so that the catalyst layer is maintained at a high temperature

  required for the practice of the reforming reaction.

  The use of a fluidized bed in the apparatus makes it possible to obtain a thermal conductivity coefficient of between 200 and

  and 250 Kcal / m 2 h G, which means that we can significantly reduce

  the length of tube necessary for the conduction of heat. When the hydrocarbon fuel gas passes through the catalyst layer, it is converted

  by reforming into a gas containing hydrogen and oxy-

  of carbon as main constituents until it reaches the upper end of the double-walled catalyst-filled tube As seen in Fig. 13c, a plurality of guide vanes 95 are arranged radially

  between the inner wall of the outer tube and the outer part

  upper end of the inner tube These fins deviate progressively from 180 the direction of flow of the hydrogen-rich gas flowing upward in the annular volume

  filled with catalyst The gas thus enters the tube

  To ensure that the heat conduction effect is

  brought to its maximum, several ribs (not shown) can

  may be attached to the inner wall of the outer tube and / or

  on the outer wall of the inner tube to produce

  repeated impacts and changes in direction of the flow

  Gas The heat-burning surface is thus noted;

increased.

  -After actèviment d-; reforming, the g: 'reaction G 2 rich in hydrogen flows down inside

  of the inner tube 88 to constitute a downward flow.

  In view of the fact that the hydrogen-rich gas has a coefficient

  higher thermal conductivity than the hydrogen-based gas

  hydrocarbons, a ribbon 96 promoting the conduction of heat and made of a heat-resistant metallic material

* as referred to by the name SUS 304 following

  JIS or similar and arranged in the inner tube, so as to maximize the advantageous characteristic of the hydrogen-rich gas, thereby obtaining a high degree of

  heat conduction surface as well as a high rate of conduction

-

  The reference numeral 94 designates a

  that of retaining the catalyst being in the form of a

  perforated plate with a large number of small holes

  stitched through it or in the form of a wire mesh plate.

  When the catalyst is used for a large number of years, it gradually deteriorates and is partially broken or sprayed.

  the base of double-walled tubes filled with catalyst and

  There is therefore a risk that this catalyst could

  disturbances such as disturbance of the uniform flow of the reforming gas, interruption of the flow of this gas or similar disturbances.

  porous catalyst retention plate avoids

  As described above, when the catalyst layer is to be examined or replaced by a new layer, the support plate 98 of the inner tube is first disassembled and then

  remove the inner tube 88 by pulling it down.

  Fig. 14 is a graph showing the temperature distribution on the double-walled tubes

  filled with catalyst On this graph, we have reported

  tion of the position in the catalyst-filled tube, the temperature

  A in the fluidized bed, the temperature B in the updraft and the temperature C in the downflow As

  as we can see on the graph, is the reaction gas? a temperature

  850 'C at the upper end of the tube

  This means that the catalyst-filled tube also functions as an efficient heat conductor for heating the fluid that arrives at the same time as it ensures that it is at a temperature of 7000 C at the outlet.

his reforming.

  As described above, each of the double-walled catalyst-filled tubes is arranged in such a way that

  the lower end part is fixed, while the

  As a variant, the arrangement can be inverted by 1800, that is to say that each

26 2531944

  Catalyst-filled tubes are suspended at their upper end and their lower end portion is left free. The fluidized bed can operate at normal pressure.

  or in a pressure-controlled atmosphere.

  It should be further noted that the present invention should not be limited to a fuel reforming apparatus, but may be implemented in a fluidized bed type heat exchanger or in a

similar device.

  Finally, we will now describe in ref 6-

  FIG. 15 illustrates a fuel reforming apparatus

  the sixth embodiment of the invention.

  In this figure, the numerical reference

  * i 2 denotes the use of a fuel reforming device.

  122 denotes a fluidized bed.

  Numeral 123 denotes an open volume located above the fluidized bed 122. The numeral 124 denotes an outer tube constituting a dowel tube wall filled with catalyst.

  and numeral 125 designates an inner tube

  also constituting this double-walled tube.

  numerical reference numeral 126 denotes a flue gas outlet duct. The numeral 127 designates a gas turbine. The numeral 128 designates a gas duct. L 1 l turbine impingement The rae-iq reference 129 designates a recovery boiler heat of gases

  exhaust and numeral 130 designates a chimney.

  Reference numeral 131 designates a

  hydrocarbon fuel feedstock The reference

  Numerical reference 132 designates a fuel tube for burners and numeral 132 'designates a series of burners which are designed as a tubular fitting. Numerical reference 133 designates a gas supply line serving as raw material and in front of The numeral 134 designates a gas mixer used as raw material and steam. The reference numeral 138 27 designates a tube for feeding the gaseous mixture of gas serving as the

raw material and steam.

  Reference numeral 135 designates a

  tubular supply of water to the boiler The reference numeral 136 designates a water pump for feeding the boiler.

  tubular steam for reforming the fuel

  The reference numeral 140 denotes a heat exchanger. The reference numeral 141 denotes a supply tube to a CO converter and numeral 142 denotes a CO converter. reference number 143

  means a converter for combustion air A

  Numeric reference 144 denotes a combustion air duct Numeral 145 designates a combustion air chamber

  and reference numeral 146 denotes an electric generator.

  We will now describe how

  of the fuel reforming apparatus constructed as a de-

written above.

  The fuel mixed with air under pressure

  The flow through the conduit 144 is burned with the burners 132 'so that a fluidized bed 122 is set

  The fluid bed can be floated by fl oating fluidized material.

  In this manner, a series of catalyst-filled double-walled tubes consisting of an outer tube 124 and an inner tube 125 are respectively heated and heated. The heating takes place in a uniform manner at a predetermined elevated temperature, so that the gas mixture is heated. As a feedstock and as steam fed through the tube 138 is reformed by passing through the catalyst layer disposed in the double-walled tubes, a reforzming gas containing hydrogen, oxide is produced. of Carbon and Carbon Dioxide as Major Constituents After Completion

  of the reforming reaction the gas produced is removed from the

  The gas 28 - produced by the reaction enters the heat exchanger where it is cooled to a predetermined temperature.

  by heat exchange The gas is then sent to the converters

  CO 142 in which the carbon monoxide releases hydrogen.

  according to the chemical formula CO + HOCO 2 + H 2.

  This produces a H gas rich in hydrogen.

  The flue gases produced by the combustion in the fluidized bed enter the gas turbine 127 in

  passing through the open volume 123 located above the fluid bed

  The gas turbine 127 is operably connected to the compressor 143 and to the electric generator 146, so that the air of

  combustion is compressed to the required pressure and that it is

  continued sent to the bed eluidized through the air duct of

  combustion 144 and the combustion air chamber 145.

  The power exceeding that which is necessary

  For the operation of the compressor: 143 is consumed to rotate the electric generator 146, this power is thus transformed into electricity After leaving the gas turbine, the exhaust gas flows into the boiler 129 for recovery of the exhaust heat In this boiler 129 takes place a heat exchange to recover

  the heat lost after which the gases are discharged into the atmosphere.

  Surrounding the chimney 130 The feed water for the boiler 129 for heat recovery

  exhaust gas is supplied by the water pump 136

  This water is vaporized in the boiler and the steam thus produced is mixed with the fuel in the mixer.

  134 gas as raw material and steam.

  By using the fluidized bed under pressure, the following advantageous characteristics can be obtained: 1) The flow rate in the volume

  can be reduced to a value lower than that which

  responds to normal pressure operation.

  mines the flow velocity in the clear space to the same value 29 -

  than that which corresponds to the operation under normal pressure

  In the case of the fluid bed, the volume required for the fluidized bed can be reduced.

  The entire device can then be built with

reduced dimensions.

  2) If the flow velocity in the cleared volume is chosen to have a lower value,

  can reduce the grain size of the maize

  The result is that the tubes filled with cata-

  in the fluidized bed are used less and that, moreover, entrainment rarely occurs in the open space

above the fluidized bed.

  3) Since the fluidisation is ef-

  under pressure, the fluidized bed has a coefficient of con-

  thermal ductility higher than that which corresponds to

  under normal pressure The thermal energy contained

  in the gases burned at high temperature is recovered under

  me of mechanical force that is used to turn the tur-

  In addition, the remaining energy is used to run an electric generator. It is thus possible to reduce the dimensions of the boiler for recovering the heat of the burned gases compared to what would take place.

  if we recover all the heat.

  Given the envelope of the reforming apparatus constituting the heaviest element, it may be

  designed with smaller dimensions, transport and

  In addition, when the device consists of several modules, the transport is performed more easily using a trailer or a

similar vehicle.

  6) A fluidized bed has a uniform temperature distribution in its extent Thus, by judiciously controlling the operation of the fluidized bed, it is certain that the tubes filled with catalyst subjected to conditions

  severe temperatures in the fluidized bed are protected against

  damage such as breaks, leaks and similar

2531944

  In addition, other characteristics may be favorably

  fluidized bed characteristics such as good

  partial load operation, excellent capacity -

  adapting to load variations at high speed and others. 31 -

Claims (6)

  1) Fuel reforming apparatus of the type comprising a plurality of catalyst-filled tubes (4; 69; 82,88; 124,125) arranged to be heated at elevated temperature by external heating so as to transform by reforming   the gas fuel containing hydrogen as constituting   main fuel, passing through each of the catalyst-filled tubes, characterized in that the catalyst-filled tubes (4; 69; 82; 88; 124,125) are arranged in a bed fluidized (24; 76,81; 122).   2) Fuel reforming apparatus according to claim 1, characterized in that a heat exchanger (19, 72) is mounted at a predetermined location, a heat exchange taking place in this exchanger between gases.   outgoing combustion and combustion air entering.   3) Fuel reforming apparatus according to claim 1, characterized in that a   recycling passage (30, 32) in which it is recirculated under pres-   part of the combustion gases taken from a duct evacuation device (28).   4) Fuel reforming apparatus   according to claim 1, characterized in that the tubes   catalyst plies (69) are arranged in a fluidized bed (76) consisting of a non-combustible fluidized material, a plurality of straight burners (60) being disposed above the floor (75) of the fluidized bed (76).    ) Fuel reforming apparatus   according to claim 1, characterized in that the tubes   catalyst folds are respectively designed as tu-   double-walled (82; 88; 124,125).   6) Fuel reforming apparatus according to claim 2, characterized in that each of the double-walled tubes (82,88) filled with catalyst has an annular volume defined between the outer tube (82) and the inner tube (88). for placing the catalyst (93), a plate 32 2 2531944   The porous catalyst support (g 4) is further attached to the outer wall surface of the inner tube, with a plurality of guide vanes (95) attached at its upper end to change the flow direction of the gas and promote conduction. heat, a ribbon (96) promoting the conduction of heat   being disposed within the inner tube (88).   Fuel reforming apparatus according to claim 1, characterized in that the fluidized bed (122) is in the form of a fluidized bed operating under pressure, a gas turbine (127) being installed in a   predetermined location and being controlled by the com gas bustion.