CA1107039A - Upflow catalytic reaction apparatus with anti- fluidization means - Google Patents
Upflow catalytic reaction apparatus with anti- fluidization meansInfo
- Publication number
- CA1107039A CA1107039A CA283,821A CA283821A CA1107039A CA 1107039 A CA1107039 A CA 1107039A CA 283821 A CA283821 A CA 283821A CA 1107039 A CA1107039 A CA 1107039A
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- Prior art keywords
- catalyst
- plate
- reactor
- bed
- column
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- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- 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
- C01B3/384—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 the catalyst being continuously externally heated
-
- 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
- B01J8/06—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 in tube reactors; the solid particles being arranged in tubes
- B01J8/062—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 in tube reactors; the solid particles being arranged in tubes being installed in a furnace
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- Chemical & Material Sciences (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Organic Chemistry (AREA)
- Health & Medical Sciences (AREA)
- General Health & Medical Sciences (AREA)
- Engineering & Computer Science (AREA)
- Combustion & Propulsion (AREA)
- Inorganic Chemistry (AREA)
- Devices And Processes Conducted In The Presence Of Fluids And Solid Particles (AREA)
- Hydrogen, Water And Hydrids (AREA)
Abstract
UPFLOW CATALYTIC REACTION APPARATUS
WITH ANTI-FLUIDIZATION MEANS
ABSTRACT OF THE DISCLOSURE
An anti-fluidization device, such as for preventing fluidization of a vertically extending catalyst bed having upward gas flow therethrough, includes a perforated plate which rests on top of the bed by its own weight and moves upwardly and downwardly as the bed expands and contracts while remaining in continuous contact with the top surface of the bed. A restraint is positioned above the plate to limit the expansion of the bed to a preselected volume. As long as the plate remains in contact with the top layer of particles and as long as the bed is not permitted to expand more than a small amount, fluidization does not occur.
WITH ANTI-FLUIDIZATION MEANS
ABSTRACT OF THE DISCLOSURE
An anti-fluidization device, such as for preventing fluidization of a vertically extending catalyst bed having upward gas flow therethrough, includes a perforated plate which rests on top of the bed by its own weight and moves upwardly and downwardly as the bed expands and contracts while remaining in continuous contact with the top surface of the bed. A restraint is positioned above the plate to limit the expansion of the bed to a preselected volume. As long as the plate remains in contact with the top layer of particles and as long as the bed is not permitted to expand more than a small amount, fluidization does not occur.
Description
~ 3 ~
BACKGROUND OF THE LNVENTION
Field of the Invention - The present invention relates to catalytic reaction apparatus and catalyst anti-fluidization means therefor.
Description of the Prior Art - Catalytic reaction apparatus for converting hydrocarbon fuels to useful industri-al gases, such as hydrogen, are well known in the art. In one type of apparatus, such as apparatus for steam reforming a hydrocarbon fuel, the process fuel is passed through a tube containing the catalyst, If the reaction is endothermic the tube is usually disposed within a furnace which provides the heat to drive the reaction. If the catalyst filled tube is vertical and the process gas flows upwardly there~hrough, the upward force of the fLowîng gas, particularly at higher through-puts, is usually greater than the weight of the catalyst par-ticles, resulting in continuous motion of the catalyst parti-cles relative to each otherO When this condition exists the catalyst bed is said to be fluidiæed. This continuous motion results in damage to the particles such as causing them to break up into smaller pieces or to wear by the friction of the particles rubbing against each other. Fine size particles are lost by being carried out of the bed with the reacting gases; and, over a period of time, the total volume of cata-lyst within the bed may be reduced to an unacceptable level, requiring replenishment of the bed, Anti-fluidization devices are well known in the art.
One common type is a spring loaded perorated member posi-tioned on top of the bed thereby maintaining the bed under
BACKGROUND OF THE LNVENTION
Field of the Invention - The present invention relates to catalytic reaction apparatus and catalyst anti-fluidization means therefor.
Description of the Prior Art - Catalytic reaction apparatus for converting hydrocarbon fuels to useful industri-al gases, such as hydrogen, are well known in the art. In one type of apparatus, such as apparatus for steam reforming a hydrocarbon fuel, the process fuel is passed through a tube containing the catalyst, If the reaction is endothermic the tube is usually disposed within a furnace which provides the heat to drive the reaction. If the catalyst filled tube is vertical and the process gas flows upwardly there~hrough, the upward force of the fLowîng gas, particularly at higher through-puts, is usually greater than the weight of the catalyst par-ticles, resulting in continuous motion of the catalyst parti-cles relative to each otherO When this condition exists the catalyst bed is said to be fluidiæed. This continuous motion results in damage to the particles such as causing them to break up into smaller pieces or to wear by the friction of the particles rubbing against each other. Fine size particles are lost by being carried out of the bed with the reacting gases; and, over a period of time, the total volume of cata-lyst within the bed may be reduced to an unacceptable level, requiring replenishment of the bed, Anti-fluidization devices are well known in the art.
One common type is a spring loaded perorated member posi-tioned on top of the bed thereby maintaining the bed under
- 2 -compression at all times to prevent fluidization. However, mechanisms of this type are expensive and it is often diffi-cult if not impossible to find a suitable spring material which will withstand the environment ol the apparatus in which it is to be used.
Complexity and expense are the major disadvantages of other mechanisms which might be useful in preventing fl~id-ization, such as the mechanism shown in U. S. Patent
Complexity and expense are the major disadvantages of other mechanisms which might be useful in preventing fl~id-ization, such as the mechanism shown in U. S. Patent
3,374,052 to Liang-tseng Fan et al.
SUMMARY OF THE INVENTION
One object of the present invention is an upflow cata~
lytic reactor having uncomplicated and inexpensive means to prevent fluidization of the catalyst bed.
According to the present invention an upflow catalytic reactor includes a vertically extending catalyst bed which is prevented from fluidizing during operation by a perfo-, rated plate which rests on the top sur~ace of the bed by itsown weight and which can move upwardly and downwardly as the bed expands and contracts while remaining in continuous con-tact with the top surface, a restraint being disposed above the plate to limit its travel and thus limit expansion of the bed to a preselected volume.
- In prior art it is generally taught that in order to prevent fluidization of a particulate bed, be it a catalyst bed or any other type of bed, the entire bed must be kept under compression. We have determined that this is not true. We have discovered that fluidization does not occur if only the top layer of particles is prevented from lifting 7~9 o~f the surface o~ the bed, as long as only a small expansion of the bed is permitted.
The basic problem with upward flow through beds of particles is the result of a pressure drop through the bed which exceeds the weight of the particles within the bed.
At this point the top layer of particles in the bed begins to lift, vibrate, and tumble. As the flow of gas through the bed is increased this particle activity progresses downwardly through the bed until large sections of the bed begin to lift and tumble in a "boiling" fashion. This is called fluidization. We have found that a perforated plate or screen which 1) si~ply sits on top of the bed in contact with the top layer of catalyst particles, 2) is not heavy enough to prevent expansion of the bed, and 3) is constructed such that the bed expands without -the me~ber first lifting off the bed, can prevent fluidization if expansion of the bed is limited to only a few percent of its nonexpanded volume. A simple restraining device or stop is positioned within the reactor whereby the perforated member is limited in its upward movement by coming into contact with the restraint.
In accordance with a specific embodiment of the invention there is provided, in a catalytic reactor for steam reforming a reformable hydrocarbon fuel including wall means defining a vertically extending reaction chamber having a lower end and an upper end, said lower end including an inlet and said upper end including an outlet, presettled catalyst particles disposed within said reaction chamber - forming a vertically extending presettlecl catalyst bed therein having a top layer of catalyst particles, said catalyst bed expanding and contracting during operation of
SUMMARY OF THE INVENTION
One object of the present invention is an upflow cata~
lytic reactor having uncomplicated and inexpensive means to prevent fluidization of the catalyst bed.
According to the present invention an upflow catalytic reactor includes a vertically extending catalyst bed which is prevented from fluidizing during operation by a perfo-, rated plate which rests on the top sur~ace of the bed by itsown weight and which can move upwardly and downwardly as the bed expands and contracts while remaining in continuous con-tact with the top surface, a restraint being disposed above the plate to limit its travel and thus limit expansion of the bed to a preselected volume.
- In prior art it is generally taught that in order to prevent fluidization of a particulate bed, be it a catalyst bed or any other type of bed, the entire bed must be kept under compression. We have determined that this is not true. We have discovered that fluidization does not occur if only the top layer of particles is prevented from lifting 7~9 o~f the surface o~ the bed, as long as only a small expansion of the bed is permitted.
The basic problem with upward flow through beds of particles is the result of a pressure drop through the bed which exceeds the weight of the particles within the bed.
At this point the top layer of particles in the bed begins to lift, vibrate, and tumble. As the flow of gas through the bed is increased this particle activity progresses downwardly through the bed until large sections of the bed begin to lift and tumble in a "boiling" fashion. This is called fluidization. We have found that a perforated plate or screen which 1) si~ply sits on top of the bed in contact with the top layer of catalyst particles, 2) is not heavy enough to prevent expansion of the bed, and 3) is constructed such that the bed expands without -the me~ber first lifting off the bed, can prevent fluidization if expansion of the bed is limited to only a few percent of its nonexpanded volume. A simple restraining device or stop is positioned within the reactor whereby the perforated member is limited in its upward movement by coming into contact with the restraint.
In accordance with a specific embodiment of the invention there is provided, in a catalytic reactor for steam reforming a reformable hydrocarbon fuel including wall means defining a vertically extending reaction chamber having a lower end and an upper end, said lower end including an inlet and said upper end including an outlet, presettled catalyst particles disposed within said reaction chamber - forming a vertically extending presettlecl catalyst bed therein having a top layer of catalyst particles, said catalyst bed expanding and contracting during operation of
4 -' 7~3g the reactor, and a perforatea plate resting by its weight alone atop said catalyst bed and extending thereacross said perforated plate having weight and pressure drop character-istics such that said plate is in continuous contact with the top layer of catalyst particles throughout operation of said reactor, the improvement comprises: restraint means fixedly located within said reactor and engageable with said perforated plate at only a single location, said single location being at a distance above said perforated plate which is no more than a few percent of the hei~ht of said catalyst bed, and wherein the weight of said perforated plate permits expansion of said bed during operation of said reactor.
From a different aspect, and in accordance with the invention, a method for preventing fluidization of a catalyst bed in a reactor having a vertical column of par-ticulate catalyst wherein ~ases flow upwardly through said :; catalyst column and said column of catalyst expands and con-tracts during operation of the reactor comprises the steps of: presettling said catalyst column prior to operation of said reactor; placing atop said presettled catalyst column at a first vertical location a perforated plate which ex-tends across the top layer of the catalyst, said perforated plate having weight and pressure drop characteristics such that said plate is in continuous contact with the top layer of catalyst particles in said column and r.ests thereon ~y its weight alone, said plate being light enough to permit expansion of said catalyst column during operation of the reactor, and, by its weight and pressure drop characteristics, moving downwardly and up~ardly in continuous contact with said top layer of catalyst as said catalyst column con-tracts - 4a -J7~3~
and expands during operation of the rea~tor~ said plate preventing the top layer of particles from li~ting off the bed, and limiting expansion of said catalyst column during operation to no more than a few percent o~ the nonexpanded volume of said column by preventing upward movement of said plate beyond a single fixed, predetermined location~
In accordance with a further embodiment of the second aspect of the invention, a method for preventing ~luidization in a catalytic reactor having a vertical column of particulate catalyst which has been presettled prior to operation of the reactor comprises the steps of flowing gases upwardly through said catalyst column, permitting said catalyst column to expand duri.ng said upward flow of gases, placing atop said presettled catalyst column at a first : vertical location a perforated plate which extends across said perforated plate having weight and pressure drop characteristics such that said plate is in continuous contact with the top layer of catalyst particles in said column and rests thereon by its weight alone, said plate being light enough to permit expansion of said catalyst column during operation of the reactor, and, by .its weight and pressure drop characteristics, moving downwardly and upwardly in con-tinuous contact with said top layer of said catalyst as said catalyst column contracts and expands during operation of the reactor, said plate preventing the top layer of particles from lifting off the bed, and limiting said expansion of said catalyst column by fixedly losating restraint means above said plate to stop upward movement of said plate, said ; restraint means bein~ engageable with said plate at a single . 30 location which is no more than a few percent of the height of the unexpanded catalyst column above said plate.
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The foregoing and other objects, features and advantages of the present invention will become more apparent in the light of the following detailed description of pre-ferred embodiments thereof as illustrated in the accompanying drawing.
BRIEF DESCRIPrrION OF rrHE DRAWING
Fig. 1 is a fragmentary, vertical, cross-sectional view - 4c -1~ U 7~
of steam reforming reactor apparatus according to the presen~
invention.
Fig. 2 is a cross-sectional view of the apparatus of Fig. 1 taken substantially along the line 2-2 in Fig. 1.
Fig. 3 is an enlarged view of the upper portion of one of the reactors of Fig. 1 showing details of the present invention.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
Consider, as an exemplary embodiment of the present in~
LO vention, the catalytic reaction apparatus 10 of Figs. 1-3.
In this embodiment, the apparatus is for the purpose of steam reforming a reformable hydrocarbon fuel in the presence of a suitable catalyst in order to produce hydrogen. The ap-paratus 10 comprises a furnace 12 including burner nozzles 14, a burner fuel manifold 16, and an air manifold 18. Dis-posed within the furnace 12 are a plurality of tubular reac-tors 20. In this embodiment there are nineteen reactors ar-ranged as shown in Fig~ 2.
Each reactor 20 comprises an outer cylindrical wall 22 and an inner cylindrical wall or center tube 24 defining an annular reaction chamber 26 therebetween. The reaction cham~
ber 26 is filled with steam reforming catalyst particles or pellets 28 which are supported on a screen 30 disposed a~ the inlet 32 of the reaction chamber. Any suitable steam reform-ing catalyst, such as nickel, may be used to fill the reaction chamber. In accordance with the present invention, antifluid-ization means 33 is disposed at the outlet 36 (Fig. 3) of the ~ 7~9 reaction chamber and is hereinafter more fully explained in conjunction with the more detailed view of Fig. 3. The cylinder which is defined by ~he outer wall 22 is closed at its upper end 38 by an and cap 40. The center tube 24 has an upper inlet end 42 and a lower outlet end 44. The inlet end 42 terminates below the end cap 40 such that the center tube is in gas communication with the outlet 36 of the reaction chamber 26.
Disposed within the center tube is a cylindrical plug 46 which has an outer diameter somewhat smaller than the inner diameter of the center tube thereby defining an annular re-generation chamber 48 ~herebetween having an inlet 49. The plug 46 may be a solid rod, but in this embodiment is a tube which is blocked by an end cap 50 at one end thereof such that reaction products exiting the reaction chamber 26 must flow around the plug 46 through the regeneration chamber 48.
Spacing between the plug 46 and the center tube 24 is main-tained by dimpLes 52 in the plug wall. For the purposes of the present embodiment, the f~mction of ~he regenera~ion chamber 48 is to return heat from the reaction products leav ing the outlet 36 back into the catalyst bed of the reaction chamber 26. The arrangement shown in Fig. 1 provides some preheating of the process fuel before it enters the catalyst bed.
Each reactor 20 may be considered to comprise an upper portion 56 and a lower portion 58. The upper portion 56 is disposed within what is hereinafter referred to as the burner cavity 60. The cavity 60 is that voluma of the furnace 12 3~
within which actual combustion of the fuel and air fed into the furnace takes place. This volume is characterized by very high temperatures, considerable radian~ heating as well as convective heating of the reactors 20, and axial (i.e., in the direction of the axis of the reactors 20), as well as radial mixing of the gases therein.
The lower portion 58 of each reactor is surrounded by a cylindrical wall or conduit 62 spaced outwardly from the wall 22 defining an annular burner gas passageway 64 therebetween having an inlet 66 and an outlet 67. The outlet 67 is adja cent th~ inlet 32 of the reaction chamber 26. The passageway 64 is filled with a heat transfer packing material such as spheres 70 of alumina supported on a screen 68. The space 72 between adjacent conduits 62 is filled with a nonheat conduc-tive material such as ceramic fiber insulation whieh is sup-ported on a plate 74 extending a~ross the furnace and which has holes therein through which the reactors 20 pass. The plate 74 and the material within ~he space 72 prevents the furnace gases from flowing around the outside of the conduits 62.
In addition to the plate 74, plates 769 78 and 80 also extend across the furnace and define manifolds therebetween.
The plate 80 rests on the bottom wall 82 of the ~urnace. The plates 78 and 80 define a reaction products manifold 84 therebetween; the plates 76 and 78 define a process fuel in-let manifold 86 therebetween; and, the plates 74 and 76 de-fine a furnace gas outlet manifold 88 therebetween. The plugs 46 and the center tubes 24 abut the bottom plate 80; the . , .
3~
outer walls 22 of the reactors abut the plate 78; and, the conduits 62 abut the plate 74 In operation, a mixture of steam and reformable hydrocar-bon fuel from the manifold 86 enters the inlet 32 of the reac-tion chamber 26 by way of the holes 100 in the wall 22; the manifold 86 is fed by a conduit 102. The mixture immediately begins to be heated by the furnace gases flowing countercur-rent thereto through the passageway 64 and begins to react in the presence of the cataLyst particles 28. As the fuel, steam and reaction products travel upward within the reaction chamber 26 they continue to react and pick up additional heat.
The hot reaction products enter the inlet 49 of the regenera-tion chamber 48. As ~he reaction products traverse the length of the annular regeneration chamber, heat is trans-ferred therefrom back into the reaction chamber 26. They thereupon enter the reaction products manifold 84 through the holes 104 in the center tube 24, and are carried away from the reactor via the conduit 106 either for further processing, storage, or consumption.
Fuel for the furnace enters the manifold 16 via a con-duit 108 and thereupon passes into the burner cavity 60 by way of the nozzles 14. Air enters the manifold 18 via a con-duit 110 and enters the burner cavity 60 via annular passage-way 112 surrounding each nozzle 14. Burning of the fuel and air takes place within the burner cavity 60. The hot gases from the burner cavity travel through the passageways 64 into the manifold 88 and are exhausted via a conduit 113.
Referring to Fig. 3, the anti-fluidization means 33 is 75~3~
comprised of a plate 90 and a restrain~ 92. The plate 90 is an annulus which simply rests by its own weight atop the cata-lyst bed in contact with the top layer of catalyst pellets.
The plate is perforated to penmit reac~ion products to pass therethrough. Its weight and pressure drop characteristics are such that it will not lift off the catalyst bed but will maintain continuous contact with the top layer of catalyst pellets during operation even as the bed expands and contracts.
This prevents the top layer of catalyst pellets from becoming fluidized, which in turn prevents the catalyst bed from be-coming fluidiæed, as long as the catalyst bed is not per-mitted to expand by more than a few percent of its volume (or axial length, which is directly proportional to volume).
If the bed is permitted to expand too much, pellets or parti-cles below the top layer will become fluidized, and this fluidization will be transmitted through the bed until the entire catalyst bed is fluidized.
The restraint 92 is provided to limit expansion of the - catalyst bed by stopping upward movement of the plate 90. In this embodiment the restraint 92 includes an annular plate 91 welded around its inner circumference 94 to the inside surface of the center tube 24. The plate 91 is perforated with holes 93 therethrough. A cylindrical flange 96 is integral with the plate 91 and e~tends vertically downwardly therefrom near its outer edge 98. The plate 91 could have been welded to the outer cylindrical wall 22 rather than the center tuhe 24;
however, axial thermal expansion of the center tube 24 is less than that of the outer wall 22 so that it is preferred to fix the plate to the center tube~
'`:
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': , ~ 3~
- As used in this speci~ication and appended claims, the "weight" of the perforated plate includ~s the weight of any-thing which may rest on or be attached to or a part o~ the plate but which moves as one with the plate. For example, although no~ shown, an annular ring may be secured to the top surface o~ tbe plate to provide additional weight. Upward movement of the plate may be stopped when the ring contacts a suitable restraint.
In practicing the present invention it must be kept in mind that, even without fluidization, ~he catalyst ~ed will settle during operation of the reactor due to operational vi-bration as well as thermal expansion and contraction of the outer wall 22 relative to the cen~er tube 24. Therefore, it is desirable to minimize, to the extent possible, settling of the catalyst bed during operation. This is accomplished by presettling the catalyst bed, such as by mechanical vibratory apparatus~ as one fills the reaction chamber 26 during assem-bly of the apparatus.
By presettling the catalyst bed, adding catalyst parti-cles to fill the void left by the presettled particles~ pre-settling the bed again, etc., the reaction chamber can be filled to the extent desired and settling during operation (ass~ming fl~dization is prevented) will thereby be mini-mized. Once the reaction chamber is filled to the desired level wîth presettled catalyst particles the perforated plate 90 is placed atop the bed and the restraint 92 is wel~ed into position. Preferably the restraint 9~ is located such that the flange 96 is in contact with the plate 90 or as close ` thereto as possible, recalling that the bed expansion will be the sum of the dis~ance between the plate 90 and the ~lange 96 plus the amount of contraction of the bed due to unavoid-able additional settling during operation of the reactor.
In one test a reactor constructed in all important re-spects like the reactor shown in Figs. 1-3 was operated for a period of 732 hours withou~ any indica~ion that fluidization of the catalyst bed had occurred. In the apparatus tested the annular reaction chamber had an outer diameter of 8.75 inches, an inner diameter o~ 6.60 inches, and a presettled catalyst bed length of 63.0 inches prior to operation of the reactor. The catalyst was in the form of cylindrical pel-lets, The plate 90 was made from Incoloy 800 alloy steel (from International Nickel Co.~ was .125 inch thick, and had inner and outer diameters of 6.62 inches and 8.55 inches, re-spectively. It was perforated over its en~ire surface with .125 inch diameter holes to the extent that the plate was 40%
porous. The annular plate 91 o the res~raint 92 had an outer diameter of 8.55 inches and was ~0% porous. The flange 96 was .38 inch long, and prior ~o operation of the reactor it was ; essentially in contact with the plate 90. After 732 hours of operation and thirty-four shutdown cycles (i.e. the apparatus is cooled to ambient temperature) settlîng of the bed amounted to only about 2% of the bed length; no further signi~icant settling is expected to occur with additional operation.
Thus~ maximum expansion o~ the bed amounted to about 2% of the bed length and fluidization did not occur~ Increase in bed pressure drop was limited to less than 4%. I~ is believed :, that if the catalyst bed is presettled, restraining the plate from moving upwardly substantially beyond its initial location will always prevent fluidization since further settling of the bed during operation will always be within acceptable limits.
It is not known just how much expansion can be tolerated without fluidization occurring. From the foregoing example it is apparent that 2% expansion is acceptable. Perhaps up to 5% expansion will be acceptable. If, prior to operation of the reactor, the restraint 92 is located at some dis~ance from the plate 90 (rather than being located as close to the plate 90 as possibLe) then the amount of expansion during operation will be that much greater. There is no particular advantage in keeping the expansion to an absolute minimum as long as expansion is stopped prior to the onset of fluidization.
It should be apparent that the reactor described in con-junction with the antifluidiæation means of the present in-vention is by way of example only. For instance, the instant invention is as useful for preventing fluidization of a cylin-drical catalyst bed as it is for the annular bed hereinabove described. It should also be apparent that the invention is not limited to use with steam reforming catalyst beds.
Although the invention has been shown and described with respect to a preferred embodiment thereof, it should be under-stood by those skilled in the art that other various changes and omissions in the form and detail thereof may be made therein without departing from the spirit and ~he scope of the invention.
From a different aspect, and in accordance with the invention, a method for preventing fluidization of a catalyst bed in a reactor having a vertical column of par-ticulate catalyst wherein ~ases flow upwardly through said :; catalyst column and said column of catalyst expands and con-tracts during operation of the reactor comprises the steps of: presettling said catalyst column prior to operation of said reactor; placing atop said presettled catalyst column at a first vertical location a perforated plate which ex-tends across the top layer of the catalyst, said perforated plate having weight and pressure drop characteristics such that said plate is in continuous contact with the top layer of catalyst particles in said column and r.ests thereon ~y its weight alone, said plate being light enough to permit expansion of said catalyst column during operation of the reactor, and, by its weight and pressure drop characteristics, moving downwardly and up~ardly in continuous contact with said top layer of catalyst as said catalyst column con-tracts - 4a -J7~3~
and expands during operation of the rea~tor~ said plate preventing the top layer of particles from li~ting off the bed, and limiting expansion of said catalyst column during operation to no more than a few percent o~ the nonexpanded volume of said column by preventing upward movement of said plate beyond a single fixed, predetermined location~
In accordance with a further embodiment of the second aspect of the invention, a method for preventing ~luidization in a catalytic reactor having a vertical column of particulate catalyst which has been presettled prior to operation of the reactor comprises the steps of flowing gases upwardly through said catalyst column, permitting said catalyst column to expand duri.ng said upward flow of gases, placing atop said presettled catalyst column at a first : vertical location a perforated plate which extends across said perforated plate having weight and pressure drop characteristics such that said plate is in continuous contact with the top layer of catalyst particles in said column and rests thereon by its weight alone, said plate being light enough to permit expansion of said catalyst column during operation of the reactor, and, by .its weight and pressure drop characteristics, moving downwardly and upwardly in con-tinuous contact with said top layer of said catalyst as said catalyst column contracts and expands during operation of the reactor, said plate preventing the top layer of particles from lifting off the bed, and limiting said expansion of said catalyst column by fixedly losating restraint means above said plate to stop upward movement of said plate, said ; restraint means bein~ engageable with said plate at a single . 30 location which is no more than a few percent of the height of the unexpanded catalyst column above said plate.
" - 4b -7~
The foregoing and other objects, features and advantages of the present invention will become more apparent in the light of the following detailed description of pre-ferred embodiments thereof as illustrated in the accompanying drawing.
BRIEF DESCRIPrrION OF rrHE DRAWING
Fig. 1 is a fragmentary, vertical, cross-sectional view - 4c -1~ U 7~
of steam reforming reactor apparatus according to the presen~
invention.
Fig. 2 is a cross-sectional view of the apparatus of Fig. 1 taken substantially along the line 2-2 in Fig. 1.
Fig. 3 is an enlarged view of the upper portion of one of the reactors of Fig. 1 showing details of the present invention.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
Consider, as an exemplary embodiment of the present in~
LO vention, the catalytic reaction apparatus 10 of Figs. 1-3.
In this embodiment, the apparatus is for the purpose of steam reforming a reformable hydrocarbon fuel in the presence of a suitable catalyst in order to produce hydrogen. The ap-paratus 10 comprises a furnace 12 including burner nozzles 14, a burner fuel manifold 16, and an air manifold 18. Dis-posed within the furnace 12 are a plurality of tubular reac-tors 20. In this embodiment there are nineteen reactors ar-ranged as shown in Fig~ 2.
Each reactor 20 comprises an outer cylindrical wall 22 and an inner cylindrical wall or center tube 24 defining an annular reaction chamber 26 therebetween. The reaction cham~
ber 26 is filled with steam reforming catalyst particles or pellets 28 which are supported on a screen 30 disposed a~ the inlet 32 of the reaction chamber. Any suitable steam reform-ing catalyst, such as nickel, may be used to fill the reaction chamber. In accordance with the present invention, antifluid-ization means 33 is disposed at the outlet 36 (Fig. 3) of the ~ 7~9 reaction chamber and is hereinafter more fully explained in conjunction with the more detailed view of Fig. 3. The cylinder which is defined by ~he outer wall 22 is closed at its upper end 38 by an and cap 40. The center tube 24 has an upper inlet end 42 and a lower outlet end 44. The inlet end 42 terminates below the end cap 40 such that the center tube is in gas communication with the outlet 36 of the reaction chamber 26.
Disposed within the center tube is a cylindrical plug 46 which has an outer diameter somewhat smaller than the inner diameter of the center tube thereby defining an annular re-generation chamber 48 ~herebetween having an inlet 49. The plug 46 may be a solid rod, but in this embodiment is a tube which is blocked by an end cap 50 at one end thereof such that reaction products exiting the reaction chamber 26 must flow around the plug 46 through the regeneration chamber 48.
Spacing between the plug 46 and the center tube 24 is main-tained by dimpLes 52 in the plug wall. For the purposes of the present embodiment, the f~mction of ~he regenera~ion chamber 48 is to return heat from the reaction products leav ing the outlet 36 back into the catalyst bed of the reaction chamber 26. The arrangement shown in Fig. 1 provides some preheating of the process fuel before it enters the catalyst bed.
Each reactor 20 may be considered to comprise an upper portion 56 and a lower portion 58. The upper portion 56 is disposed within what is hereinafter referred to as the burner cavity 60. The cavity 60 is that voluma of the furnace 12 3~
within which actual combustion of the fuel and air fed into the furnace takes place. This volume is characterized by very high temperatures, considerable radian~ heating as well as convective heating of the reactors 20, and axial (i.e., in the direction of the axis of the reactors 20), as well as radial mixing of the gases therein.
The lower portion 58 of each reactor is surrounded by a cylindrical wall or conduit 62 spaced outwardly from the wall 22 defining an annular burner gas passageway 64 therebetween having an inlet 66 and an outlet 67. The outlet 67 is adja cent th~ inlet 32 of the reaction chamber 26. The passageway 64 is filled with a heat transfer packing material such as spheres 70 of alumina supported on a screen 68. The space 72 between adjacent conduits 62 is filled with a nonheat conduc-tive material such as ceramic fiber insulation whieh is sup-ported on a plate 74 extending a~ross the furnace and which has holes therein through which the reactors 20 pass. The plate 74 and the material within ~he space 72 prevents the furnace gases from flowing around the outside of the conduits 62.
In addition to the plate 74, plates 769 78 and 80 also extend across the furnace and define manifolds therebetween.
The plate 80 rests on the bottom wall 82 of the ~urnace. The plates 78 and 80 define a reaction products manifold 84 therebetween; the plates 76 and 78 define a process fuel in-let manifold 86 therebetween; and, the plates 74 and 76 de-fine a furnace gas outlet manifold 88 therebetween. The plugs 46 and the center tubes 24 abut the bottom plate 80; the . , .
3~
outer walls 22 of the reactors abut the plate 78; and, the conduits 62 abut the plate 74 In operation, a mixture of steam and reformable hydrocar-bon fuel from the manifold 86 enters the inlet 32 of the reac-tion chamber 26 by way of the holes 100 in the wall 22; the manifold 86 is fed by a conduit 102. The mixture immediately begins to be heated by the furnace gases flowing countercur-rent thereto through the passageway 64 and begins to react in the presence of the cataLyst particles 28. As the fuel, steam and reaction products travel upward within the reaction chamber 26 they continue to react and pick up additional heat.
The hot reaction products enter the inlet 49 of the regenera-tion chamber 48. As ~he reaction products traverse the length of the annular regeneration chamber, heat is trans-ferred therefrom back into the reaction chamber 26. They thereupon enter the reaction products manifold 84 through the holes 104 in the center tube 24, and are carried away from the reactor via the conduit 106 either for further processing, storage, or consumption.
Fuel for the furnace enters the manifold 16 via a con-duit 108 and thereupon passes into the burner cavity 60 by way of the nozzles 14. Air enters the manifold 18 via a con-duit 110 and enters the burner cavity 60 via annular passage-way 112 surrounding each nozzle 14. Burning of the fuel and air takes place within the burner cavity 60. The hot gases from the burner cavity travel through the passageways 64 into the manifold 88 and are exhausted via a conduit 113.
Referring to Fig. 3, the anti-fluidization means 33 is 75~3~
comprised of a plate 90 and a restrain~ 92. The plate 90 is an annulus which simply rests by its own weight atop the cata-lyst bed in contact with the top layer of catalyst pellets.
The plate is perforated to penmit reac~ion products to pass therethrough. Its weight and pressure drop characteristics are such that it will not lift off the catalyst bed but will maintain continuous contact with the top layer of catalyst pellets during operation even as the bed expands and contracts.
This prevents the top layer of catalyst pellets from becoming fluidized, which in turn prevents the catalyst bed from be-coming fluidiæed, as long as the catalyst bed is not per-mitted to expand by more than a few percent of its volume (or axial length, which is directly proportional to volume).
If the bed is permitted to expand too much, pellets or parti-cles below the top layer will become fluidized, and this fluidization will be transmitted through the bed until the entire catalyst bed is fluidized.
The restraint 92 is provided to limit expansion of the - catalyst bed by stopping upward movement of the plate 90. In this embodiment the restraint 92 includes an annular plate 91 welded around its inner circumference 94 to the inside surface of the center tube 24. The plate 91 is perforated with holes 93 therethrough. A cylindrical flange 96 is integral with the plate 91 and e~tends vertically downwardly therefrom near its outer edge 98. The plate 91 could have been welded to the outer cylindrical wall 22 rather than the center tuhe 24;
however, axial thermal expansion of the center tube 24 is less than that of the outer wall 22 so that it is preferred to fix the plate to the center tube~
'`:
~g_ ~`
': , ~ 3~
- As used in this speci~ication and appended claims, the "weight" of the perforated plate includ~s the weight of any-thing which may rest on or be attached to or a part o~ the plate but which moves as one with the plate. For example, although no~ shown, an annular ring may be secured to the top surface o~ tbe plate to provide additional weight. Upward movement of the plate may be stopped when the ring contacts a suitable restraint.
In practicing the present invention it must be kept in mind that, even without fluidization, ~he catalyst ~ed will settle during operation of the reactor due to operational vi-bration as well as thermal expansion and contraction of the outer wall 22 relative to the cen~er tube 24. Therefore, it is desirable to minimize, to the extent possible, settling of the catalyst bed during operation. This is accomplished by presettling the catalyst bed, such as by mechanical vibratory apparatus~ as one fills the reaction chamber 26 during assem-bly of the apparatus.
By presettling the catalyst bed, adding catalyst parti-cles to fill the void left by the presettled particles~ pre-settling the bed again, etc., the reaction chamber can be filled to the extent desired and settling during operation (ass~ming fl~dization is prevented) will thereby be mini-mized. Once the reaction chamber is filled to the desired level wîth presettled catalyst particles the perforated plate 90 is placed atop the bed and the restraint 92 is wel~ed into position. Preferably the restraint 9~ is located such that the flange 96 is in contact with the plate 90 or as close ` thereto as possible, recalling that the bed expansion will be the sum of the dis~ance between the plate 90 and the ~lange 96 plus the amount of contraction of the bed due to unavoid-able additional settling during operation of the reactor.
In one test a reactor constructed in all important re-spects like the reactor shown in Figs. 1-3 was operated for a period of 732 hours withou~ any indica~ion that fluidization of the catalyst bed had occurred. In the apparatus tested the annular reaction chamber had an outer diameter of 8.75 inches, an inner diameter o~ 6.60 inches, and a presettled catalyst bed length of 63.0 inches prior to operation of the reactor. The catalyst was in the form of cylindrical pel-lets, The plate 90 was made from Incoloy 800 alloy steel (from International Nickel Co.~ was .125 inch thick, and had inner and outer diameters of 6.62 inches and 8.55 inches, re-spectively. It was perforated over its en~ire surface with .125 inch diameter holes to the extent that the plate was 40%
porous. The annular plate 91 o the res~raint 92 had an outer diameter of 8.55 inches and was ~0% porous. The flange 96 was .38 inch long, and prior ~o operation of the reactor it was ; essentially in contact with the plate 90. After 732 hours of operation and thirty-four shutdown cycles (i.e. the apparatus is cooled to ambient temperature) settlîng of the bed amounted to only about 2% of the bed length; no further signi~icant settling is expected to occur with additional operation.
Thus~ maximum expansion o~ the bed amounted to about 2% of the bed length and fluidization did not occur~ Increase in bed pressure drop was limited to less than 4%. I~ is believed :, that if the catalyst bed is presettled, restraining the plate from moving upwardly substantially beyond its initial location will always prevent fluidization since further settling of the bed during operation will always be within acceptable limits.
It is not known just how much expansion can be tolerated without fluidization occurring. From the foregoing example it is apparent that 2% expansion is acceptable. Perhaps up to 5% expansion will be acceptable. If, prior to operation of the reactor, the restraint 92 is located at some dis~ance from the plate 90 (rather than being located as close to the plate 90 as possibLe) then the amount of expansion during operation will be that much greater. There is no particular advantage in keeping the expansion to an absolute minimum as long as expansion is stopped prior to the onset of fluidization.
It should be apparent that the reactor described in con-junction with the antifluidiæation means of the present in-vention is by way of example only. For instance, the instant invention is as useful for preventing fluidization of a cylin-drical catalyst bed as it is for the annular bed hereinabove described. It should also be apparent that the invention is not limited to use with steam reforming catalyst beds.
Although the invention has been shown and described with respect to a preferred embodiment thereof, it should be under-stood by those skilled in the art that other various changes and omissions in the form and detail thereof may be made therein without departing from the spirit and ~he scope of the invention.
Claims (9)
1. In a catalytic reactor for steam reforming a reform-able hydrocarbon fuel including wall means defining a vertically extending reaction chamber having a lower end and an upper end, said lower end including an inlet and said upper end including an outlet, presettled catalyst particles disposed within said reaction chamber forming a vertically extending presettled catalyst bed therein having a top layer of catalyst particles, said catalyst bed expanding and contracting during operation of the reactor, and a perforated plate resting by its weight alone atop said catalyst bed and extending there-across said perforated plate having weight and pressure drop characteristics such that said plate is in continuous con-tact with the top layer of catalyst particles throughout operation of said reactor, the improvement comprising:
restraint means fixedly located within said reactor and engageable with said perforated plate at only a single location, said single location being at a distance above said perforated plate which is no more than a few percent of the height of said catalyst bed, and wherein the weight of said perforated plate permits expansion of said bed during opera-tion of said reactor.
restraint means fixedly located within said reactor and engageable with said perforated plate at only a single location, said single location being at a distance above said perforated plate which is no more than a few percent of the height of said catalyst bed, and wherein the weight of said perforated plate permits expansion of said bed during opera-tion of said reactor.
2. The reactor according to claim 1 wherein said restraint means is fixedly attached to said wall means.
3. The reactor according to claim 1 wherein said reactor chamber is an annular reaction chamber and said wall means includes an inner cylindrical wall and an outer cylin-drical wall spaced apart to define said annular reaction cham-ber, and said perforated plate means is a first annular plate.
4. The reactor according to claim 3 wherein said restraint means is fixedly attached to said inner cylindrical wall.
5. The reactor according to claim 3 wherein said re-straint means includes a perforated second annular plate having an inner circumference and an outer circumference, said inner circumference fixedly secured to said inner cylin-drical wall, said second annular plate including a cylin-drical flange extending vertically toward said first annular plate, said flange being engageable with said first annular plate to limit upward movement thereof.
6. The catalytic reactor according to claim 1 wherein said distance above said plate means is never more than about 5% of the height of said catalyst bed.
7. A method for preventing fluidization of a catalyst bed in a reactor having a vertical column of particulate catalyst wherein gases flow upwardly through said catalyst column and said column of catalyst expands and contracts during operation of the reactor comprising the steps of:
presettling said catalyst column prior to operation of said reactor;
placing atop said presettled catalyst column at a first vertical location a perforated plate which extends across the top layer of the catalyst, said perforated plate having weight and pressure drop characteristics such that said plate is in continuous contact with the top layer of catalyst particles in said column and rests thereon by its weight alone, said plate being light enough to permit ex-pansion of said catalyst column during operation of the reactor, and, by its weight and pressure drop characteristics, moving downwardly and upwardly in continuous contact with said top layer of catalyst as said catalyst column contracts and expands during operation of the reactor, said plate pre-venting the top layer of particles from lifting off the bed;
and limiting expansion of said catalyst column during operation to no more than a few percent of the nonexpanded volume of said column by preventing upward movement of said plate beyond a single fixed, predetermined location.
presettling said catalyst column prior to operation of said reactor;
placing atop said presettled catalyst column at a first vertical location a perforated plate which extends across the top layer of the catalyst, said perforated plate having weight and pressure drop characteristics such that said plate is in continuous contact with the top layer of catalyst particles in said column and rests thereon by its weight alone, said plate being light enough to permit ex-pansion of said catalyst column during operation of the reactor, and, by its weight and pressure drop characteristics, moving downwardly and upwardly in continuous contact with said top layer of catalyst as said catalyst column contracts and expands during operation of the reactor, said plate pre-venting the top layer of particles from lifting off the bed;
and limiting expansion of said catalyst column during operation to no more than a few percent of the nonexpanded volume of said column by preventing upward movement of said plate beyond a single fixed, predetermined location.
8. The method for preventing fluidization according to claim 7 wherein said step of limiting expansion includes limiting expansion to no more than about 5% of the non-expanded volume of said column of particulate catalyst.
9. A method for preventing fluidization in a catalytic reactor having a vertical column of particulate catalyst which has been presettled prior to operation of the reactor comprising the steps of:
flowing gases upwardly through said catalyst column;
permitting said catalyst column to expand during said upward flow of gases;
placing atop said presettled catalyst column at a first vertical location a perforated plate which extends across said perforated plate having weight and pressure drop characteristics such that said plate is in continuous contact with the top layer of catalyst particles in said column and rests thereon by its weight alone, said plate being light enough to permit expansion of said catalyst column during operation of the reactor, and, by its weight and pressure drop characteristics, moving downwardly and upwardly in continuous contact with said top layer of said catalyst as said catalyst column contracts and expands during operation of the reactor, said plate preventing the top layer of par-ticles from lifting off the bed; and limiting said expansion of said catalyst column by fixedly locating restraint means above said plate to stop upward movement of said plate, said restraint means being engageable with said plate at a single location which is no more than a few percent of the height of the unexpanded catalyst column above said plate.
flowing gases upwardly through said catalyst column;
permitting said catalyst column to expand during said upward flow of gases;
placing atop said presettled catalyst column at a first vertical location a perforated plate which extends across said perforated plate having weight and pressure drop characteristics such that said plate is in continuous contact with the top layer of catalyst particles in said column and rests thereon by its weight alone, said plate being light enough to permit expansion of said catalyst column during operation of the reactor, and, by its weight and pressure drop characteristics, moving downwardly and upwardly in continuous contact with said top layer of said catalyst as said catalyst column contracts and expands during operation of the reactor, said plate preventing the top layer of par-ticles from lifting off the bed; and limiting said expansion of said catalyst column by fixedly locating restraint means above said plate to stop upward movement of said plate, said restraint means being engageable with said plate at a single location which is no more than a few percent of the height of the unexpanded catalyst column above said plate.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US75333676A | 1976-12-22 | 1976-12-22 | |
| US753,336 | 1976-12-22 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1107039A true CA1107039A (en) | 1981-08-18 |
Family
ID=25030214
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA283,821A Expired CA1107039A (en) | 1976-12-22 | 1977-08-01 | Upflow catalytic reaction apparatus with anti- fluidization means |
Country Status (6)
| Country | Link |
|---|---|
| JP (1) | JPS5379766A (en) |
| CA (1) | CA1107039A (en) |
| DE (1) | DE2751309A1 (en) |
| FR (1) | FR2374949A1 (en) |
| GB (1) | GB1564994A (en) |
| IL (1) | IL53403A (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US6767519B2 (en) | 2000-03-15 | 2004-07-27 | Hitachi, Ltd. | Chemical decontamination liquid decomposing system having catalyst tower and catalyst tower therefor |
Families Citing this family (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS59116215U (en) * | 1983-01-27 | 1984-08-06 | 三菱自動車工業株式会社 | vehicle door |
| GB8401989D0 (en) * | 1984-01-25 | 1984-02-29 | Martin S R | Heating apparatus |
| US5164163A (en) * | 1988-09-19 | 1992-11-17 | Kabushiki Kaisha Kobe Seiko Sho | Hydrocarbon reforming apparatus |
| JPH03232703A (en) * | 1989-12-26 | 1991-10-16 | Tokyo Electric Power Co Inc:The | Reformer of hydrocarbon |
| EP3772372A1 (en) | 2019-08-05 | 2021-02-10 | L'air Liquide, Societe Anonyme Pour L'etude Et L'exploitation Des Procedes Georges Claude | Method for preventing fluidizazion in an upward-flow catalytic fixed bed reactor |
| GB202015185D0 (en) * | 2020-09-25 | 2020-11-11 | Johnson Matthey Davy Technologies Ltd | Improvements in or relating to catalyst carriers for tubular reactors and associated methods |
Family Cites Families (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US2173844A (en) * | 1935-07-19 | 1939-09-26 | Houdry Process Corp | Heat exchange |
| US3374052A (en) * | 1965-12-20 | 1968-03-19 | Dept Of Chemical Engineering | System for solid particles-fluid contact operations |
| US3541729A (en) * | 1968-05-09 | 1970-11-24 | Gen Electric | Compact reactor-boiler combination |
| US3691065A (en) * | 1970-07-17 | 1972-09-12 | Texaco Inc | Selective temperature control of catalysts |
| DE2336030A1 (en) * | 1973-07-14 | 1975-01-30 | Bamag Verfahrenstechnik Gmbh | Granular treatment bed uniformly maintained during settlement - by pressing grating into surface to subdivide it into cells |
| US3909299A (en) * | 1973-10-01 | 1975-09-30 | United Technologies Corp | Fuel cell system including reform reactor |
| DE2521710A1 (en) * | 1975-05-15 | 1976-11-18 | Siemens Ag | REACTOR FOR THE CATALYTIC REVISION OF HYDROCARBONS WITH AN OXYGEN-CONTAINING GAS |
-
1977
- 1977-08-01 CA CA283,821A patent/CA1107039A/en not_active Expired
- 1977-11-15 FR FR7734288A patent/FR2374949A1/en active Granted
- 1977-11-16 IL IL53403A patent/IL53403A/en unknown
- 1977-11-16 DE DE19772751309 patent/DE2751309A1/en active Granted
- 1977-11-18 GB GB48124/77A patent/GB1564994A/en not_active Expired
- 1977-11-29 JP JP14323777A patent/JPS5379766A/en active Granted
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US6767519B2 (en) | 2000-03-15 | 2004-07-27 | Hitachi, Ltd. | Chemical decontamination liquid decomposing system having catalyst tower and catalyst tower therefor |
| US6982060B2 (en) | 2000-03-15 | 2006-01-03 | Hitachi, Ltd. | Chemical decontamination liquid decomposing system having catalyst tower and catalyst tower therefor |
Also Published As
| Publication number | Publication date |
|---|---|
| FR2374949A1 (en) | 1978-07-21 |
| DE2751309A1 (en) | 1978-06-29 |
| IL53403A0 (en) | 1978-01-31 |
| JPS577536B2 (en) | 1982-02-10 |
| DE2751309C2 (en) | 1988-04-14 |
| FR2374949B1 (en) | 1983-08-19 |
| IL53403A (en) | 1981-03-31 |
| JPS5379766A (en) | 1978-07-14 |
| GB1564994A (en) | 1980-04-16 |
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