CA1214318A - Reaction tube or vessel for an exothermic catalytic gas reaction of a heterogeneous gas mixture, especially for methanation - Google Patents
Reaction tube or vessel for an exothermic catalytic gas reaction of a heterogeneous gas mixture, especially for methanationInfo
- Publication number
- CA1214318A CA1214318A CA000444218A CA444218A CA1214318A CA 1214318 A CA1214318 A CA 1214318A CA 000444218 A CA000444218 A CA 000444218A CA 444218 A CA444218 A CA 444218A CA 1214318 A CA1214318 A CA 1214318A
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- Canada
- Prior art keywords
- section
- reaction
- tube
- vessel
- temperature
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
Links
- 238000006243 chemical reaction Methods 0.000 title claims abstract description 75
- 239000000203 mixture Substances 0.000 title description 6
- 230000003197 catalytic effect Effects 0.000 title 1
- 239000012495 reaction gas Substances 0.000 claims abstract description 34
- 239000003054 catalyst Substances 0.000 claims abstract description 33
- 239000007789 gas Substances 0.000 claims abstract description 29
- 239000002245 particle Substances 0.000 claims abstract description 27
- 239000011949 solid catalyst Substances 0.000 claims abstract description 24
- 238000011144 upstream manufacturing Methods 0.000 claims abstract description 11
- 239000000463 material Substances 0.000 claims description 13
- 238000001816 cooling Methods 0.000 claims description 9
- 239000000306 component Substances 0.000 claims 2
- CURLTUGMZLYLDI-UHFFFAOYSA-N Carbon dioxide Chemical compound O=C=O CURLTUGMZLYLDI-UHFFFAOYSA-N 0.000 abstract description 10
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 abstract description 9
- 229910002092 carbon dioxide Inorganic materials 0.000 abstract description 5
- 229910002091 carbon monoxide Inorganic materials 0.000 abstract description 4
- UGFAIRIUMAVXCW-UHFFFAOYSA-N Carbon monoxide Chemical compound [O+]#[C-] UGFAIRIUMAVXCW-UHFFFAOYSA-N 0.000 abstract description 3
- 239000001569 carbon dioxide Substances 0.000 abstract description 3
- 229910052739 hydrogen Inorganic materials 0.000 abstract description 3
- 239000001257 hydrogen Substances 0.000 abstract description 3
- 125000004435 hydrogen atom Chemical class [H]* 0.000 abstract 1
- VNWKTOKETHGBQD-UHFFFAOYSA-N methane Chemical compound C VNWKTOKETHGBQD-UHFFFAOYSA-N 0.000 description 8
- 239000000047 product Substances 0.000 description 7
- 230000015572 biosynthetic process Effects 0.000 description 3
- 238000003786 synthesis reaction Methods 0.000 description 3
- PXHVJJICTQNCMI-UHFFFAOYSA-N Nickel Chemical compound [Ni] PXHVJJICTQNCMI-UHFFFAOYSA-N 0.000 description 2
- 230000032683 aging Effects 0.000 description 2
- 238000009835 boiling Methods 0.000 description 2
- 238000000034 method Methods 0.000 description 2
- 239000003345 natural gas Substances 0.000 description 2
- 230000007704 transition Effects 0.000 description 2
- UFHFLCQGNIYNRP-UHFFFAOYSA-N Hydrogen Chemical compound [H][H] UFHFLCQGNIYNRP-UHFFFAOYSA-N 0.000 description 1
- 208000036366 Sensation of pressure Diseases 0.000 description 1
- 239000000969 carrier Substances 0.000 description 1
- 239000007795 chemical reaction product Substances 0.000 description 1
- 239000003153 chemical reaction reagent Substances 0.000 description 1
- 238000010276 construction Methods 0.000 description 1
- 239000002826 coolant Substances 0.000 description 1
- 230000018109 developmental process Effects 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 230000003467 diminishing effect Effects 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 239000002737 fuel gas Substances 0.000 description 1
- 150000002431 hydrogen Chemical class 0.000 description 1
- 229910052759 nickel Inorganic materials 0.000 description 1
- 238000000926 separation method Methods 0.000 description 1
Classifications
-
- 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
-
- C—CHEMISTRY; METALLURGY
- C07—ORGANIC CHEMISTRY
- C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
- C07C1/00—Preparation of hydrocarbons from one or more compounds, none of them being a hydrocarbon
- C07C1/02—Preparation of hydrocarbons from one or more compounds, none of them being a hydrocarbon from oxides of a carbon
- C07C1/04—Preparation of hydrocarbons from one or more compounds, none of them being a hydrocarbon from oxides of a carbon from carbon monoxide with hydrogen
- C07C1/0405—Apparatus
- C07C1/041—Reactors
Landscapes
- Chemical & Material Sciences (AREA)
- Organic Chemistry (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Engineering & Computer Science (AREA)
- General Chemical & Material Sciences (AREA)
- Oil, Petroleum & Natural Gas (AREA)
- Devices And Processes Conducted In The Presence Of Fluids And Solid Particles (AREA)
- Organic Low-Molecular-Weight Compounds And Preparation Thereof (AREA)
- Industrial Gases (AREA)
Abstract
Abstract of the Disclosure A methanation reaction of a gas containing hydrogen, carbon monoxide and carbon dioxide which is exothermic and takes place in a bed of solid catalyst particles in a reaction vessel through which the reaction gas flows is substantially improved by the use of an apparatus in which an upstream section and a downstream section, both containing particles of the same catalyst, are provided, the sections having different cross-sectional dimen-sions and appropriate lengths. The reaction vessel is cooled by pressurized water confined by an external pressure container. The ratio of the hydraulic diameter of the first section to the equivalent diameter of the catalyst particles therein is less than the corresponding ratio for the second section;
and the length of the first section is such that the reaction gas, after having reached a maximum temperature, is cooled down, before the gas passes into the second section, to a temperature low enough for the temperature in the second section to remain below the maximum permissible temperature. The length of the second section needs to be only enough to establish thermodynamic equilibirum at a temperature corresponding to the desired product gas quality, preferably between the range between 311° and 370°C. For reduction of the hydraulic diameter in a tube of given dimensions, inert particles or confining bodies can be put in the tube along with the catalyst particles.
and the length of the first section is such that the reaction gas, after having reached a maximum temperature, is cooled down, before the gas passes into the second section, to a temperature low enough for the temperature in the second section to remain below the maximum permissible temperature. The length of the second section needs to be only enough to establish thermodynamic equilibirum at a temperature corresponding to the desired product gas quality, preferably between the range between 311° and 370°C. For reduction of the hydraulic diameter in a tube of given dimensions, inert particles or confining bodies can be put in the tube along with the catalyst particles.
Description
9~2~3~
This invention concerns a tubular reaction vessel for an exo-thermic reaction between gaseous components of a reaction gas, such as may be used for methanizing a synthesis gas containing carbon monoxide, carbon dioxide and hydrogen. A bed of solid catalyst pieces is loosely aggregated in the vessel and the reaction gas flows through the bed and reacts at the surface of the catalyst while the vessel is externally cooled. The reaction vessel has a connection for supplying the reaction gas at one end and is connected at its outlet with a gas line for leading away the product gas.
In the case of exothermic gas reactions using solid catalyst pieces, care must be taken that the heat of reaction does not overheat the solid catalyst to a damaging or otherwise impermissible degree. The speed at which the reaction heat is set free depends notonly on the constitution and state of the reaction gas, but also on the catalyst quality and the catalyst volume that actively participates in the running of the reaction. The heating-up of the catalyst is held down by external cooling of the reaction tube. On the other hand, the reaction product that is drawn off as product gas should be at a prescribed thermodynamic equilibrium when it is removed from the reaction tube. For this purpose, the tube length and pressure loss in the reaction tube need to be limited to practical magnitudes, from the structural and economic point of view. The requirements to be met for holding these conditions within appropriate limits opera~e at least in part in opposition to each other.
Reaction tubes filled with solid catalyst bodies for carrying out the reaction are known which have a constant tube diameter. Gases are methanized therein consisting essentially of hydrogen, H2, carbon monoxide, CO, carbon dioxide, CO2, and methane, CH~. Fuel gases are produced by methaniz-ing, for example, which may replace natural gas available from natural wells.
~L2~
Alternatively, gases can be generated that serve as energy carriers in a dis-tance range energy circulation system, such as is described in German Patent 1,298,233, or in German published patent application (AS) 1,601,001.
In methanation -the CH4 component of the gas is increased by exothermic reactions taking place at the solid catalyst bodies as follows:
C0 ~ 3H Cl{ + ll o il 298 1 = -206 kJ~mol C2 ~ 4H2 = CH4 ~ 2H20 ll 298 K = -165 kJ/mol The gas that is formed after separation of the water produced by the reaction is of such quality that it may be fed directly into a natural gas pipeline or distribution system or, a.s above noted, it can be reformed anew with steam in a long distance energy transport loop~ The heat arising in the reaction tube can be removed by a cooling medium, in which connection com-pare, for example, DE OS 25 29 316 and DE OS 29 49 588.
In the use of reaction tubes with a tube diameter that remains the same along its length, it has up to now been impossible, even with the use of qualitatively dif:Eerent catalyst materlals on different lengths of the tube, to meet properly all the above given conditions for the carrying out of the process. If different catalyst materials are installed in the reaction tube, through which the reagent gas flows in succession, noticeable disadvan-tages in the carrying out of the process arise, especially because of the different aging of the individual catalyst layers and the shifting of the temperature maximum in the catalyst bed resulting from the differences in aging.
It is an object of the present invention to provide apparatus which will make possible the carrying out of the reaction with the use of a solid catalyst of predetermined quality in such a way that, with limited pres-sure loss, overheati.ng of the solid catalyst is avoidable on the one hand, and, on the other hand, a gas mixture existing in thermodynamic equilibrium is made available at a prescribed temperature at the outlet of the apparatus.
Briefly, the apparatus allows the reaction gas to flow successive-ly through tubular sections of different diameters, the upstream tubular section having a hydraulic diameter, referred to the equivalent diameter of the solid catalyst particles in this section, which is smaller than the hydraulic diameter of the next downstream section referred to the equivalent diameter of the solid catalyst particles in the downstream section. Furthermore, the upstream section has a length such that the reaction gas therein, after reach-ing a maximum permissible reaction temperature, can be cooled down before it passes to the downstream section to a temperature such that in the downstream section the temperature of the reaction gas remains below the maximum permis-sible temperature therein.
By "hydraulic diameter" of a tubular section there is meant herein the diameter of a cylindrical tube of the same diameter conforming to the relation:
dh = ~ f/U
where f = the free flow cross-section of the pipe, and U = the circumference of the free flow cross-section.
By "equivalent diamete~',as used above, there is meant a diameter of a sphere having the same volume as one of the catalyst particles. The equivalent diameter dg is calculated, beginning with the sphere volume Vk = 16 ~ d 3 according to the relation:
dg = 31 6 Vp/~
V = the particle volume.
~2~
Taking account of the ratio of the hydraulic tube diameter to the equivalent diameter leads, on the one lland, to improvement in the removal of reaction heat by the smaller hydraulic tube diameter and, on thc other hand, the ratio of geome~ric surface to the volume of the catalyst particle is significant for the yield of the reaction. In the determination of this ratio, merely the geometric da-ta of the empty tube section, i.e. empty of catalyst particles, is the basis of the calculation of the hydraulic tube diameter.
The dimensions of the catalyst particles are disregarded in this calculation.
According to the invention, the first tube section is designed with such a length that in this section the reaction gas, after reaching a maximum permis-sible reaction temperature, can be cooled down, before its passage into the second tube section, to such a temperature that in that second tube section the temperature of the reaction gas remains below the maximum permissible tempera-ture. This principle is based on the recognition that the danger of over-h0ating of the solid catalyst exists mainly in the first region of the reaction tube. Consequently, particular care is taken in this region to provide a great deal of heat removal therefrom. In the :Eollowing second tube section, the desired thermodynamic equilibrium sets in at a prescribed temperature. This sub-division of the reaction tube into two sections, each fitted to the pro-gress of the reaction, leads to relatively short reaction tubes and to low pressure losses.
In a modified embodiment of the reaction vessel, provision is made for introduction into the first tube section of passage confining bodies that reduce the hydraulic tube diameter of the tubular section while behaving inertly, rather than catalytically, with respect to the exothermic reaction.
In determining of the ratio of the hydraulic tube diameter to the equivalent diameter of the particles, the passage-confining bodies are to be taken account ~.43~
of exclusively in cletermining the hydraulic diameter. The equivalent diameter of the particles remains unaffected by the dimensions of the passage-confining bodies.
The first tube section preferably has a smaller tube diameter than the succeeding tube section. This brings into consideration reaction tubes that widen conically as viewed in the flow direction of the reaction gas. For increasing the cooling effect, the first tube section can be replaced by a plurality of individual tubes leading into a common second tube section. In that case the sum of the hydraulic diameters of the individual tubes is to be determined as the hydraulic tube diameter of the first section.
The invention is further described by way of illustrative examples with reference to the annexed drawings, in which:
Figure 1 is a schematic diagram of a reaction vessel having two tubular sections of respectively different diameters, operating in tandem, and Figure 2 is an elevation view of a reaction vessel according to the invention in which the upstream sec-tion is a group of parallel tubular sections, and the downstream section is a single tubular section.
Figure 1 shows a reaction tube 1 having a supply tube 2 connected to it at the top through which a reaction gas for an exothermic reaction can be introduced. The reaction vessel 1 is filled with a bed of solid catalyst particles 3 of a material that is a catalyst for the reaction of the components of the reaction with one another. The vessel 1 is externally cooled over its entire length 4. In the Figure 1 embodiment, the reaction vessel 1 is sur-rounded by a pressure container (not shown in the drawing), which is filled with water which is maintained therein under pressure. The water boils through picking up the heat generated by the reaction. A product gas is drawn off from the outlet 5 through a gas line 6.
~Z1~
The reaction gas begins its flow through the reaction vessel by flowing through a first tube section 7 having a length 8. The first tube section has a smaller inner diameter 9 than the second tube 10. Tube 10 follows the first tube section 7, to which it is joined by a transition piece ll that widens in the direction of flow of the reaction gas from the diameter 9 to a larger diameter 12. In the illustrated example, both tube sections 7 and 10 are cylindrical. In this case, the hydraulic tube diameter of these tube sections correspond to the inner tube diameters 9 and 12, respectively.
Solid catalyst particles 13, all of the same catalyst material, are put into both tube sections 7 and lO of the reaction vessel and are piled up in a bed which leaves spaces between the particles through which the reaction gas can flow. The amount of heat developed during the reaction, per unit of catalyst mass, is known for each specified state of the reaction, when a single particular catalyst material is used for the entire reaction. For a given gas throughput of a reaction gas of specified gas composition, and for a given solid catalyst volume, the ratio of the hydraulic tube diameter to the equivalent diameter of the catalyst particles is now established in the first tube section 7 at a value for which, with constant water temperature in the pressure container which surrounds the reaction tube 1, the maximum permissible temperature for the particular solid catalyst material is not overstepped. The reaction gas reacts quickly as it enters the first tube section 7, with considerable development of heat. After reaching the maximum temperature the conversion rate of the components of the reaction gas comes back down and the speed at which the reaction takes place is no-ticeably reduced.
The ratio of the hydralic tube diameter to the equivalent dia-meter is greater in the second tube section 10 than in the first tube section 7.
4~
The ratio is so determined that a tube lcngth which is as short as possible is sufficient for the establishment of the desired thermodynamic equilibrium at a specified temperature for the product gas. The length of the first tube section 7 is accordingly so dimensioned that the reaction gas is cooled down before its passage into the second tube section 10 to a temperature such that even in the second tube section, from which a lower quantity of heat is removed per unit of time by the water boiling in the surrounding pressure container, the maximum permissible temperature will not be overstepped.
Instead of making the first section of the reaction vessel l a single tube 7, as shown in Figure 1, it is also possible to employ, as the first section of the reaction vessel, a plurality of tubes 107, as shown in Figure 2. These tubes 107 discharge into the transition part lll of a common second tube section 110. The individual tubes 107, together with the tube 110, are filled with solid catalyst particles in the same manner as in the case of Figure 1. Furthermore, the tubes 107 and 110 cooled by water circulating around the reaction vessel within a pressurized container (not shown). In this case the sum of the hydraulic diameters of all individual tubes 107 has to be determined for calculating the pertinent ratio of the hydraulic tube diameter to equivalent diameter according to the invention. Once again, for diminishing the hydraulic tube diameter, inert free-path-reducing bodies can be placed in the reaction vessel which have catalytically inert properties for the reaction.
Some specific exemplifications of the practising of the invention will now be given.
For methani~ing of a synthesis gas having a composition of 10%
Cl14, 9% CO, 10% CO2, 67% ll2 and 4% N2, all by volume, in a reaction vessel of the kind shown in Figure 1 having the two respective tube sections 7 and 10, a water pressure of 100 bar was established in the outer pressure container (not shown in Figure l).
The boiling temperature of the water at this pressure is 311C.
The reaction vessel 1 was Eilled with solid catalyst particles which consisted oE a ccramic nickel-based catalyst material suitable for high-temperature methanation of the kind available, for example, under the trade designation MCR-2x (supplied by the firm ~laldor Topsoe A/S). Tlle catalyst particles were of cylindrical shape, having an average diameter and an average height of, in eacll case, 4.3 mm. In consequence, the resulting equivalent dg was about 4.9 mm. The maximum permissible operating temperature for this catalyst material is 700C. It was Eound that if the entering reaction gas of the above-given composition initially had a temperature of 300C and reacted without cooling, a temperature of about 780C would be reached as the adiabatic limiting tem-perature in the reaction vessel 1. For the desired product gas quality, how-ever, the outflowing product gas must be at a thermodynamic equilibrium temperature between 311 and, at most, 370C.
To maintain these boundary conditions in the case of a throughput of 1.8 kilomoles of reaction gas per hour, subjected to the specified reaction kinetic data for the catalyst ~ICR-2x, it was found that the reaction vessel should be designed for an overall length of eight meters, with its first tubu-lar section 7 having a length of three meters and a diameter of 25 mm, and with its second -tubular section lO having a diameter of 50 mm, and, as in-dicated, a length of five meters.
For catalyst particles of the same kind as in Example 1, but hav-ing an average diameter and an average height in each case of 8 mm, these dimensions become, for a throughput of 6.7 kilomoles of reaction gas per hour:
~,12~3~
First Tllbe Section 7 Second Tube Section 10 .
Length 3 m Length 5 m Diameter 50 mm Diameter 70 mm The overall length of the reaction vessel 1 in this second case was accordingly 8 meters.
~ ith the same catalyst material as in the previous material and for the same boundary conditions for cooling of the reaction vessel 1, a reaction vessel was designed for a throughput of 9 kilomoles of reaction gas per hour through a reaction vessel having its solid catalyst particles of two different sizes in the respective tube sections. In the first tube section 7 of the reaction vessel l, cylindrical solid catalyst particles of an average diameter of 8 mm and average height of 8 mm, were provided; while in the second tube section 10, solid catalyst particles of average diameter of 4.3 mm and average height of 4.3 mm, were provided as the filling. For this case a length of 3 meters and a diameter of 50 mm resulted for the appropriate di-mensions of the first tube section 7, with a diameter of 70 mm resulting for the second tube section 10. The overall length of the reaction vessel was less than 7 meters. In this construction of the reaction vessel l, it was possible, in spite of the substantially higher throughput, to obtain a com-position for the product gas flowing ou-t of the vessel which corresponded to the thermodynamic equilibrium of the synthesis gas in the temperature region between 311 and 370C.
_ g _
This invention concerns a tubular reaction vessel for an exo-thermic reaction between gaseous components of a reaction gas, such as may be used for methanizing a synthesis gas containing carbon monoxide, carbon dioxide and hydrogen. A bed of solid catalyst pieces is loosely aggregated in the vessel and the reaction gas flows through the bed and reacts at the surface of the catalyst while the vessel is externally cooled. The reaction vessel has a connection for supplying the reaction gas at one end and is connected at its outlet with a gas line for leading away the product gas.
In the case of exothermic gas reactions using solid catalyst pieces, care must be taken that the heat of reaction does not overheat the solid catalyst to a damaging or otherwise impermissible degree. The speed at which the reaction heat is set free depends notonly on the constitution and state of the reaction gas, but also on the catalyst quality and the catalyst volume that actively participates in the running of the reaction. The heating-up of the catalyst is held down by external cooling of the reaction tube. On the other hand, the reaction product that is drawn off as product gas should be at a prescribed thermodynamic equilibrium when it is removed from the reaction tube. For this purpose, the tube length and pressure loss in the reaction tube need to be limited to practical magnitudes, from the structural and economic point of view. The requirements to be met for holding these conditions within appropriate limits opera~e at least in part in opposition to each other.
Reaction tubes filled with solid catalyst bodies for carrying out the reaction are known which have a constant tube diameter. Gases are methanized therein consisting essentially of hydrogen, H2, carbon monoxide, CO, carbon dioxide, CO2, and methane, CH~. Fuel gases are produced by methaniz-ing, for example, which may replace natural gas available from natural wells.
~L2~
Alternatively, gases can be generated that serve as energy carriers in a dis-tance range energy circulation system, such as is described in German Patent 1,298,233, or in German published patent application (AS) 1,601,001.
In methanation -the CH4 component of the gas is increased by exothermic reactions taking place at the solid catalyst bodies as follows:
C0 ~ 3H Cl{ + ll o il 298 1 = -206 kJ~mol C2 ~ 4H2 = CH4 ~ 2H20 ll 298 K = -165 kJ/mol The gas that is formed after separation of the water produced by the reaction is of such quality that it may be fed directly into a natural gas pipeline or distribution system or, a.s above noted, it can be reformed anew with steam in a long distance energy transport loop~ The heat arising in the reaction tube can be removed by a cooling medium, in which connection com-pare, for example, DE OS 25 29 316 and DE OS 29 49 588.
In the use of reaction tubes with a tube diameter that remains the same along its length, it has up to now been impossible, even with the use of qualitatively dif:Eerent catalyst materlals on different lengths of the tube, to meet properly all the above given conditions for the carrying out of the process. If different catalyst materials are installed in the reaction tube, through which the reagent gas flows in succession, noticeable disadvan-tages in the carrying out of the process arise, especially because of the different aging of the individual catalyst layers and the shifting of the temperature maximum in the catalyst bed resulting from the differences in aging.
It is an object of the present invention to provide apparatus which will make possible the carrying out of the reaction with the use of a solid catalyst of predetermined quality in such a way that, with limited pres-sure loss, overheati.ng of the solid catalyst is avoidable on the one hand, and, on the other hand, a gas mixture existing in thermodynamic equilibrium is made available at a prescribed temperature at the outlet of the apparatus.
Briefly, the apparatus allows the reaction gas to flow successive-ly through tubular sections of different diameters, the upstream tubular section having a hydraulic diameter, referred to the equivalent diameter of the solid catalyst particles in this section, which is smaller than the hydraulic diameter of the next downstream section referred to the equivalent diameter of the solid catalyst particles in the downstream section. Furthermore, the upstream section has a length such that the reaction gas therein, after reach-ing a maximum permissible reaction temperature, can be cooled down before it passes to the downstream section to a temperature such that in the downstream section the temperature of the reaction gas remains below the maximum permis-sible temperature therein.
By "hydraulic diameter" of a tubular section there is meant herein the diameter of a cylindrical tube of the same diameter conforming to the relation:
dh = ~ f/U
where f = the free flow cross-section of the pipe, and U = the circumference of the free flow cross-section.
By "equivalent diamete~',as used above, there is meant a diameter of a sphere having the same volume as one of the catalyst particles. The equivalent diameter dg is calculated, beginning with the sphere volume Vk = 16 ~ d 3 according to the relation:
dg = 31 6 Vp/~
V = the particle volume.
~2~
Taking account of the ratio of the hydraulic tube diameter to the equivalent diameter leads, on the one lland, to improvement in the removal of reaction heat by the smaller hydraulic tube diameter and, on thc other hand, the ratio of geome~ric surface to the volume of the catalyst particle is significant for the yield of the reaction. In the determination of this ratio, merely the geometric da-ta of the empty tube section, i.e. empty of catalyst particles, is the basis of the calculation of the hydraulic tube diameter.
The dimensions of the catalyst particles are disregarded in this calculation.
According to the invention, the first tube section is designed with such a length that in this section the reaction gas, after reaching a maximum permis-sible reaction temperature, can be cooled down, before its passage into the second tube section, to such a temperature that in that second tube section the temperature of the reaction gas remains below the maximum permissible tempera-ture. This principle is based on the recognition that the danger of over-h0ating of the solid catalyst exists mainly in the first region of the reaction tube. Consequently, particular care is taken in this region to provide a great deal of heat removal therefrom. In the :Eollowing second tube section, the desired thermodynamic equilibrium sets in at a prescribed temperature. This sub-division of the reaction tube into two sections, each fitted to the pro-gress of the reaction, leads to relatively short reaction tubes and to low pressure losses.
In a modified embodiment of the reaction vessel, provision is made for introduction into the first tube section of passage confining bodies that reduce the hydraulic tube diameter of the tubular section while behaving inertly, rather than catalytically, with respect to the exothermic reaction.
In determining of the ratio of the hydraulic tube diameter to the equivalent diameter of the particles, the passage-confining bodies are to be taken account ~.43~
of exclusively in cletermining the hydraulic diameter. The equivalent diameter of the particles remains unaffected by the dimensions of the passage-confining bodies.
The first tube section preferably has a smaller tube diameter than the succeeding tube section. This brings into consideration reaction tubes that widen conically as viewed in the flow direction of the reaction gas. For increasing the cooling effect, the first tube section can be replaced by a plurality of individual tubes leading into a common second tube section. In that case the sum of the hydraulic diameters of the individual tubes is to be determined as the hydraulic tube diameter of the first section.
The invention is further described by way of illustrative examples with reference to the annexed drawings, in which:
Figure 1 is a schematic diagram of a reaction vessel having two tubular sections of respectively different diameters, operating in tandem, and Figure 2 is an elevation view of a reaction vessel according to the invention in which the upstream sec-tion is a group of parallel tubular sections, and the downstream section is a single tubular section.
Figure 1 shows a reaction tube 1 having a supply tube 2 connected to it at the top through which a reaction gas for an exothermic reaction can be introduced. The reaction vessel 1 is filled with a bed of solid catalyst particles 3 of a material that is a catalyst for the reaction of the components of the reaction with one another. The vessel 1 is externally cooled over its entire length 4. In the Figure 1 embodiment, the reaction vessel 1 is sur-rounded by a pressure container (not shown in the drawing), which is filled with water which is maintained therein under pressure. The water boils through picking up the heat generated by the reaction. A product gas is drawn off from the outlet 5 through a gas line 6.
~Z1~
The reaction gas begins its flow through the reaction vessel by flowing through a first tube section 7 having a length 8. The first tube section has a smaller inner diameter 9 than the second tube 10. Tube 10 follows the first tube section 7, to which it is joined by a transition piece ll that widens in the direction of flow of the reaction gas from the diameter 9 to a larger diameter 12. In the illustrated example, both tube sections 7 and 10 are cylindrical. In this case, the hydraulic tube diameter of these tube sections correspond to the inner tube diameters 9 and 12, respectively.
Solid catalyst particles 13, all of the same catalyst material, are put into both tube sections 7 and lO of the reaction vessel and are piled up in a bed which leaves spaces between the particles through which the reaction gas can flow. The amount of heat developed during the reaction, per unit of catalyst mass, is known for each specified state of the reaction, when a single particular catalyst material is used for the entire reaction. For a given gas throughput of a reaction gas of specified gas composition, and for a given solid catalyst volume, the ratio of the hydraulic tube diameter to the equivalent diameter of the catalyst particles is now established in the first tube section 7 at a value for which, with constant water temperature in the pressure container which surrounds the reaction tube 1, the maximum permissible temperature for the particular solid catalyst material is not overstepped. The reaction gas reacts quickly as it enters the first tube section 7, with considerable development of heat. After reaching the maximum temperature the conversion rate of the components of the reaction gas comes back down and the speed at which the reaction takes place is no-ticeably reduced.
The ratio of the hydralic tube diameter to the equivalent dia-meter is greater in the second tube section 10 than in the first tube section 7.
4~
The ratio is so determined that a tube lcngth which is as short as possible is sufficient for the establishment of the desired thermodynamic equilibrium at a specified temperature for the product gas. The length of the first tube section 7 is accordingly so dimensioned that the reaction gas is cooled down before its passage into the second tube section 10 to a temperature such that even in the second tube section, from which a lower quantity of heat is removed per unit of time by the water boiling in the surrounding pressure container, the maximum permissible temperature will not be overstepped.
Instead of making the first section of the reaction vessel l a single tube 7, as shown in Figure 1, it is also possible to employ, as the first section of the reaction vessel, a plurality of tubes 107, as shown in Figure 2. These tubes 107 discharge into the transition part lll of a common second tube section 110. The individual tubes 107, together with the tube 110, are filled with solid catalyst particles in the same manner as in the case of Figure 1. Furthermore, the tubes 107 and 110 cooled by water circulating around the reaction vessel within a pressurized container (not shown). In this case the sum of the hydraulic diameters of all individual tubes 107 has to be determined for calculating the pertinent ratio of the hydraulic tube diameter to equivalent diameter according to the invention. Once again, for diminishing the hydraulic tube diameter, inert free-path-reducing bodies can be placed in the reaction vessel which have catalytically inert properties for the reaction.
Some specific exemplifications of the practising of the invention will now be given.
For methani~ing of a synthesis gas having a composition of 10%
Cl14, 9% CO, 10% CO2, 67% ll2 and 4% N2, all by volume, in a reaction vessel of the kind shown in Figure 1 having the two respective tube sections 7 and 10, a water pressure of 100 bar was established in the outer pressure container (not shown in Figure l).
The boiling temperature of the water at this pressure is 311C.
The reaction vessel 1 was Eilled with solid catalyst particles which consisted oE a ccramic nickel-based catalyst material suitable for high-temperature methanation of the kind available, for example, under the trade designation MCR-2x (supplied by the firm ~laldor Topsoe A/S). Tlle catalyst particles were of cylindrical shape, having an average diameter and an average height of, in eacll case, 4.3 mm. In consequence, the resulting equivalent dg was about 4.9 mm. The maximum permissible operating temperature for this catalyst material is 700C. It was Eound that if the entering reaction gas of the above-given composition initially had a temperature of 300C and reacted without cooling, a temperature of about 780C would be reached as the adiabatic limiting tem-perature in the reaction vessel 1. For the desired product gas quality, how-ever, the outflowing product gas must be at a thermodynamic equilibrium temperature between 311 and, at most, 370C.
To maintain these boundary conditions in the case of a throughput of 1.8 kilomoles of reaction gas per hour, subjected to the specified reaction kinetic data for the catalyst ~ICR-2x, it was found that the reaction vessel should be designed for an overall length of eight meters, with its first tubu-lar section 7 having a length of three meters and a diameter of 25 mm, and with its second -tubular section lO having a diameter of 50 mm, and, as in-dicated, a length of five meters.
For catalyst particles of the same kind as in Example 1, but hav-ing an average diameter and an average height in each case of 8 mm, these dimensions become, for a throughput of 6.7 kilomoles of reaction gas per hour:
~,12~3~
First Tllbe Section 7 Second Tube Section 10 .
Length 3 m Length 5 m Diameter 50 mm Diameter 70 mm The overall length of the reaction vessel 1 in this second case was accordingly 8 meters.
~ ith the same catalyst material as in the previous material and for the same boundary conditions for cooling of the reaction vessel 1, a reaction vessel was designed for a throughput of 9 kilomoles of reaction gas per hour through a reaction vessel having its solid catalyst particles of two different sizes in the respective tube sections. In the first tube section 7 of the reaction vessel l, cylindrical solid catalyst particles of an average diameter of 8 mm and average height of 8 mm, were provided; while in the second tube section 10, solid catalyst particles of average diameter of 4.3 mm and average height of 4.3 mm, were provided as the filling. For this case a length of 3 meters and a diameter of 50 mm resulted for the appropriate di-mensions of the first tube section 7, with a diameter of 70 mm resulting for the second tube section 10. The overall length of the reaction vessel was less than 7 meters. In this construction of the reaction vessel l, it was possible, in spite of the substantially higher throughput, to obtain a com-position for the product gas flowing ou-t of the vessel which corresponded to the thermodynamic equilibrium of the synthesis gas in the temperature region between 311 and 370C.
_ g _
Claims (5)
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. A reaction tube for an exothermic reaction between gaseous com-ponents of a reaction gas comprising a loose aggregate of solid catalyst pieces through which said reaction gas is capable of flowing, said catalyst pieces being of a material capable of catalysing said exothermal reaction and being contained in a tubular vessel, and means for external cooling of said tubular vessel, said tubular vessel further having an inlet connection at its inlet end for said reaction gas and a connection at its outlet end to a conduit, for leading away a product gas produced in said vessel, said tubular vessel further comprising two tube sections connected in tandem, of which a first tube section disposed at the upstream end of gas flow in said tubular vessel has a hydraulic tube diameter which, as compared to the equivalent diameter of said catalyst pieces aggregate contained in said first section, is smaller than the hydraulic diameter of a second tube section immediately downstream there-from as referred to the equivalent diameter of said catalyst pieces aggregate contained in said second section, said first tube section having a length such that the reaction gas therein, after reaching a maximum permissible temperature, can be cooled by said cooling means before passing into said second section to such a temperature that the resultant temperature of said reaction gas in said second section remains below the maximum permissible temperature therein.
2. A reaction tube as defined in claim 1, in which in said first section of said tubular vessel, confining bodies of catalytically inert material for reducing the magnitude of the hydraulic tube diameter are inter-mixed in said aggregates of solid catalyst particles.
3. A reaction vessel for an exothermic reaction between gaseous components of a reaction gas containing therein a loose aggregate of solid catalyst pieces through which said reaction gas is capable of flowing, said catalyst pieces being of a material capable of catalyzing said exothermal reaction, equipped with means for external cooling of the vessel, the vessel having an inlet connection, said vessel further comprising a downstream section having at its downstream end a connection to an outlet conduit for leading away a product gas produced in said vessel, said downstream section having a hydraulic tube diameter, as referred to the equivalent diameter of said catalyst piece aggregate therein, of a first magnitude, and a plurality of upstream tubular sections respectively having junctions with the upstream end of said downstream tubular section and respectively having at their upstream ends inlet connections for receiving said reaction gas from a gas supply means, the sum of the hydraulic tube diameters of said upstream sections, being of a second magnitude which, referred to the sum of the equivalent diameters of said catalyst piece aggregates in the respective upstream sections, is smaller than said first magnitude of hydraulic diameter referred to equivalent dia-meter of the catalyst piece aggregate in said downstream tubular section;
each said upstream tubular section having a length such that the reaction gas therein, after reaching a maximum permissible temperature, can be cooled by said cooling means before passing into said downstream section to a temperature which will result in the temperature of said reaction gas in said second section remaining below the maximum permissible temperature therein.
each said upstream tubular section having a length such that the reaction gas therein, after reaching a maximum permissible temperature, can be cooled by said cooling means before passing into said downstream section to a temperature which will result in the temperature of said reaction gas in said second section remaining below the maximum permissible temperature therein.
4. Apparatus as defined in claim 1, or 2, or 3, in which obstruction pieces of catalytically inert material for reducing the magnitude of the hydraulic tube diameter are intermixed in said aggregates of solid catalyst particles.
5. Apparatus according to claim 1, or 2, or 3, in which the length of said second tubular section is determined so as to provide cooling of the product gas to an equilibrium temperature in the range of 310° to 370°C.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| DE19823247821 DE3247821A1 (en) | 1982-12-23 | 1982-12-23 | REACTION TUBE FOR AN EXOTHERMAL, HETEROGENICALLY CATALYZED GAS REACTION, IN PARTICULAR TO LEAD A METHANIZATION REACTION |
| DEP3247821.6-41 | 1982-12-23 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1214318A true CA1214318A (en) | 1986-11-25 |
Family
ID=6181629
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000444218A Expired CA1214318A (en) | 1982-12-23 | 1983-12-23 | Reaction tube or vessel for an exothermic catalytic gas reaction of a heterogeneous gas mixture, especially for methanation |
Country Status (5)
| Country | Link |
|---|---|
| JP (1) | JPS59133293A (en) |
| CA (1) | CA1214318A (en) |
| DE (1) | DE3247821A1 (en) |
| FR (1) | FR2538265A1 (en) |
| GB (1) | GB2132111B (en) |
Families Citing this family (10)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE4207905A1 (en) * | 1992-03-12 | 1993-09-16 | Bayer Ag | FIXED BED REACTORS WITH SHORT CATALYST BED IN FLOW DIRECTION |
| US7124918B2 (en) | 2003-05-04 | 2006-10-24 | Jodi Rascoe | Beading tool and method |
| US20050135978A1 (en) * | 2003-10-14 | 2005-06-23 | Mourad Hamedi | Method and apparatus for optimizing throughput in a trickle bed reactor |
| JP5641693B2 (en) * | 2005-12-19 | 2014-12-17 | ビーピー エクスプロレーション オペレーティング カンパニー リミテッドＢｐ Ｅｘｐｌｏｒａｔｉｏｎ Ｏｐｅｒａｔｉｎｇ Ｃｏｍｐａｎｙ Ｌｉｍｉｔｅｄ | Process for the production of condensed phase products from one or more gas phase reactants |
| RU2440400C2 (en) * | 2010-02-01 | 2012-01-20 | Инфра Текнолоджиз Лтд | Method for obtaining synthetic liquid hydrocarbons and reactor for carrying out fischer-tropsch synthesis |
| DE102010040757A1 (en) | 2010-09-14 | 2012-03-15 | Man Diesel & Turbo Se | Tube reactor |
| JP2019098323A (en) * | 2017-11-30 | 2019-06-24 | 株式会社Ihi | Reaction apparatus |
| CN108428607B (en) * | 2017-12-31 | 2025-02-25 | 宁波大学 | Ion source with temperature control function and working method thereof |
| DE102018113735A1 (en) | 2018-06-08 | 2019-12-12 | Man Energy Solutions Se | Process, tube bundle reactor and reactor system for carrying out catalytic gas phase reactions |
| JP2020093216A (en) * | 2018-12-12 | 2020-06-18 | 株式会社Ihi | Catalyst reaction device |
Family Cites Families (9)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US2248734A (en) * | 1940-06-12 | 1941-07-08 | Standard Oil Dev Co | Manufacture of hydrocarbon products by hydrogenation of oxides of carbon |
| FR1031052A (en) * | 1950-01-19 | 1953-06-19 | Ruhrchemie Ag | Process for obtaining hydrocarbons |
| GB689214A (en) * | 1950-01-19 | 1953-03-25 | Ruhrchemie Ag | Method of producing hydrocarbons |
| DE926784C (en) * | 1950-01-20 | 1955-04-25 | Metallgesellschaft Ag | Process for the extraction of hydrocarbons |
| US3172739A (en) * | 1962-02-06 | 1965-03-09 | Koniewiez | |
| US3516800A (en) * | 1965-08-25 | 1970-06-23 | Hisao Yamamoto | Synthesis reaction apparatus equipped with means for temperature control of catalyst bed |
| DE1767347A1 (en) * | 1967-05-01 | 1971-09-09 | Nat Res Dev | Tube reactor for catalytic reactions |
| DE2430769A1 (en) * | 1974-06-26 | 1976-01-15 | Linde Ag | METHOD FOR CARRYING OUT A STRONGLY EXOTHERMAL CHEMICAL REACTION |
| DE2929300A1 (en) * | 1979-07-19 | 1981-01-29 | Linde Ag | Reactor for heterogeneous catalyst gas phase reactions - is cross sectionally tailored to specific heat requirements in different reaction stages |
-
1982
- 1982-12-23 DE DE19823247821 patent/DE3247821A1/en not_active Withdrawn
-
1983
- 1983-12-13 FR FR8319913A patent/FR2538265A1/en not_active Withdrawn
- 1983-12-19 GB GB08333783A patent/GB2132111B/en not_active Expired
- 1983-12-22 JP JP24108483A patent/JPS59133293A/en active Pending
- 1983-12-23 CA CA000444218A patent/CA1214318A/en not_active Expired
Also Published As
| Publication number | Publication date |
|---|---|
| GB2132111A (en) | 1984-07-04 |
| DE3247821A1 (en) | 1984-09-27 |
| FR2538265A1 (en) | 1984-06-29 |
| JPS59133293A (en) | 1984-07-31 |
| GB2132111B (en) | 1987-07-01 |
| GB8333783D0 (en) | 1984-01-25 |
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