BE358257A - - Google Patents

Description

       

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  ItAPPARE IL CATAIYTIQPE "-1
The present invention relates to converters for catalytic reactions in the vapor phase and more particularly via converters provided as the main cooling means with a gas cooling system. reaction.



     In the past, two types of converters have been used for vapor phase catalysis, namely: gas cooled converters, usually at
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 by means of the reaction gases, and those able to, dl-tin Eefro-idisse- ment by bath, either boiling or not boiling. Bath-cooled converters, while having a

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 very strong cooling power, nevertheless have a certain number of drawbacks. Firstly, their construction is relatively very expensive, and, especially when tubular converters with small tubes are used, the number of gas-tight gaskets is very large, which increases the risk of failure.

   Gas-cooled converters have many advantages, but their cooling power is relatively less efficient than that of bath-cooled converters, due to the relatively lower specific heat of the cooling medium used. This has seriously restricted the use of gas-cooled converters in the field of highly exothermic, or very sensitive reactions, such as, for example, the oxidation of organic compounds, certain organic reductions and the like.



   Gas cooled converters have been provided with automatic temperature control by means of double countercurrent heat exchange elements, and other types of effectively cooled converters have been used. Although it is possible to set up converters of the gas-cooled type, and in particular of the automatic gas-cooled type, so as to provide remarkably smooth temperature control in highly exothermic reactions, it is frequently impossible to control. control.

   reaction by gas cooling alone, however efficient the heat exchange may be, because the heat capacity of the gases, if fully utilized, may be insufficient to take care of the heat given off by the gas. reaction without dilutions so high that they seriously affect the yields.

   Even when the heat capacity can be sufficient for normal operation, in the case of many sensitive reactions,

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 such as, for example, organic oxidations in intermediate products, there is always a tendency to. that the reaction becomes uncontrollable since any considerable rise in temperature, even if it is only of short duration, tends to push the oxidation too far, and frequently until complete combustion, with an enormous increase in the heat released;

   therefore, for many reactions, a simple automatic gas-cooled converter does not have a sufficiently high safety factor.
According to the present invention, the drawbacks of a simple gas-cooled converter system are avoided, while retaining the advantages thereof, by the application of means for recirculating at least a part. gases. reacted, with or without partial or complete separation of the desired end products. By this means, the concentration of reactive ingredients can be controlled with great precision and overreaction can be prevented.

   In addition to this feature, there is. a second advantage, very important, in the fact that it is possible, in the case of many reactions, in particular reactions where. the end product is less volatile than the starting material, making use of a circulation velocity and, as a result, a contact time with the catalyst, far exceeding any gas velocities that could be to use economically in a straight line once-through converter, because it is clear that even if at high gas speeds or with specially dosed and stabilized catalysts the percentage conversion may be below from the economic limit, it does not matter in converter systems of the present invention since the unreacted material is,

   naturally after a suitable adjustment of the concentration of reactive materials, recirculation and it is thus possible to make

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 use of enormous gas velocities which, of course, means high yields without any sacrifice in percent yield, or with a sacrifice small enough to be, economically, unimportant.



   The recirculation principles which form the main feature of the converters of the present invention can be applied with or without partial or complete separation of the final product prior to recirculation of the gases. The need to separate the final product before recirculation depends primarily on the nature of the reaction. Thus, in many reactions, such as, for example, certain organic oxidations, the end product may be more stable than the starting materials. An example of this type of reaction is the production of phthalic anhydride, starting from naphthalene, by means of well stabilized catalysts. In such cases, it is not necessary to separate all of the product as it does not suffer a significant loss in recirculation.



   In other reactions, such as a number of organic reductions and very sensitive reactions, such as certain cydations, the end product may be relatively unstable at high temperature, or may be relatively easily attacked by the constituents of the reactive gases. In such cases, it is necessary to separate substantially all of the final product before re-circulation. However, for simplicity, most of the accompanying drawings will represent systems in which the final product is not separated. It goes, of course, without saying that separator systems, such as those shown in Figs. 27 and
28, may be used whenever found desirable, or may be substituted for any other type of suitable system.



   There is no need to re-circulate

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 tion all, or even a major part, of the gases. and one of the advantages of the invention is that it can be applied to suitable types of powerfully gas-cooled converters, as a safety valve or as a means of combating sudden increases in temperature. reaction temperature, which is inevitable in many reactions.

   The decision as to the proportion of reaction gas which will normally be recirculated should, in each case, depend on the particular operation to be done, and the invention includes systems in which the recirculated gases constitute. a major part, or a small part, of the total gas flow.



   Gas-cooled automatic converters with double counter-current heat exchange flow are the preferred types to which the present invention is applicable but it will be understood that other types of powerfully cooled converters can be used. gases, such as for example those shown in FIG. 10, in FIG. 12, in FIG. 15, etc ..., and the invention, in its more general aspects, can therefore be applied to any converter, cooled by gas, having suitable cooling power.



   Although one can rely on re-circulating it to control even highly exothermic reactions, it does not of course ensure a uniform temperature throughout the converter, but acts as a control of the total heat released. Automatic gas-cooled converters with double counter-current heat exchange, especially when the cooling elements are very close together and when there are uneven cooling effects, such as. those due to the converter casing, are duly compensated, produce a remarkably uniform temperature throughout the layer of

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 catalyst with which they are associated.

   However, for some sensitive or strongly exothermic reactions there is still some danger of local hot spots forming. This danger can be avoided almost completely by making use of auxiliary temperature equalizing means which constitute the second feature of the invention.



  These means may consist of bodies such as metal rods of high thermal conductivity dispersed throughout the contact mass and preferably arranged vertically in order to effect vertical temperature equalization; or they may consist of filled containers of liquids having high thermal conductivity, such as, for example, certain metals and alloys, or, finally, such containers may be filled with liquids which boil at reaction temperatures, or at reaction temperatures. around these, or which boil to a certain degree above the reaction temperatures,

   so as to act as a safety valve when the reaction threatens to get out of control 'These temperature equalizing means can be of the most varied kinds and can be suitably arranged with respect to gas cooled heat exchanger elements, like this is shown in some of the accompanying drawings.

   When the conductivity of these auxiliary temperature equalizing means is very high, and more particularly when use is made of vessels containing liquids which boil at or around the reaction temperature, some of the heat given off by the reaction can be removed by said means by subjecting a part thereof, and in particular, in the case of those containing boiling liquids, the vapor spaces, to auxiliary cooling by means, for example. , a wind of cold air or gas.

   However, in all cases, the auxiliary means serve to equalize the temperature at

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 inside the gas-cooled z.one. and are important in many of the reactions for which the converter systems of this present. invention are suitable.



   In some reactions, especially reductions, where it is necessary to recirculate but where the heat given off is not excessive, it may be desirable to provide gas cooling or cooling by temperature equalizing means for maximum temperature. portion only of the catalyst, either by only partially embedding the gas-cooled heat exchangers in the catalyst layer, or by providing additional uncooled layers, or by any other suitable method and it goes without saying that such systems Converters are within the scope of the present invention and are of importance in some of the applications thereof.



   Most of the figures in the drawings show a single converter; but it is advantageous in some reactions, especially reactions which proceed in stages, to use two or more converters in series as shown, for example * in FIG. 28, and this modification of the recirculation principles of the present invention is within the scope thereof and is of great importance for certain reactions.



   Converter systems realizing the principles of the invention are applicable to the most varied types of organic oxidation such as:
1- Reactions in which an intermediate oxidation product is obtained - Oxidation of benzol, toluol, phenol, tar or furfurol phenols and other compounds containing the group -CH2-CH @ CH- CH2- to maleic acid and fumaric acid or mesotartaric acid; cresol to salicylic aldehyde and salicylic acid; toluol and the various halogenated and nitrated substituted toluols, in aldehydes and acids

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 correspondents; xylenes, pseudocumene, mesitylene, paracymene and other derivatives with the corresponding aldehydes and acids;

   naphthalene to naphthaquinone, phthalic anhydride and ma- laic acid phthalic hydride to maleic acid and fumaric acid; anthracene to anthraquinone; phenanthrene to phenanthraquinone, diphenic acid, phthalic anhydride and maleic acid; acenaphthene to acenaphthylene, acenaphthaquinone, bisacenaphytylidenedione, naphthaldehyaic acid, naphthalic anhydriue and hemimellithic acid; fluorene to fluorenone; eugenol and isoeugenol to vanillin and vanillic acid; methyl alcohol and methane to formaldehyde; ethyl alcohol to acetic acid; ethylene chlorohydrin to chloroacetic acid, etc ...



   2- Reactions in which an unwanted impurity is burned, such as the purification of anthracnes, crude of various degrees of impurity with total combustion of carbazol, unused oils and, in certain cases, of phenanthrene; the purification of crude mothballs and crude mononuclear hydrocarbons, such as benzols, etc ...; the purification of ammonia from coal tar with combustion of organic impurities such as phenolics present, etc ...



   3- Oxidation of mixtures of organic compounds to desired intermediates with removal of impurities, for example. : oxidation of crude anthracenes, crude phenanthrenes, etc. to intermediate products such as anthraquinone, phenanthraquinone, diphenic acid, phthalic anhydride, etc .... -, with concomitant removal of carbazol and oils without use by total combustion; oxidation of crude tar acids to male.ic and fumaric acids with cowbus- tion of certain impurities, etc ...



   Reductions and hydrogenations such as the reduction of. nitro compounds, for example: nitro-benzine, dini-

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   trobenzine, nitrophenol, nitronaphthaline and their homologues, in the corresponding amines or the corresponding hydrogenated amines; reduction of aldehydes and ketones to alcohols,
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 for example: benzyl aldehyde to benzyl alcohol, acetic aldehyde to ethyl alcohol ,. crotonic aldehyde in the corresponding butyl alcohol e.tc ....,.; the reduction of oxides of. carbon to methanol, methane, aloals, higher and ketones or petroleum-like products .; 1 * hydragenatian from aromatic compounds to 41icyclic compounds, for example:

   benzine to cyclohexane, naphthalene to tetralin or decaline, anthracene to hydrogenated anthracenes, phenol to cyclohexanol,
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 acetylene to ethylene and ethane, etc., polybase-a acids to "esters", or saline ethers, interior, for example: phthalic anhydride to phthalide, acid. camphor.:h.qt1e. in campholide, etc ...; reduction of nitrogen-containing heterocyclic compounds to aliphatic amines, for example; pyridine to amylamine., are also of importance.



   In addition to reactions in which a more or less homogeneous raw material is reduced, certain mixtures of raw materials can be effectively reduced with or without the presence of gas. additional reducing agents. Thus, for example, carbon oxides can be reduced in the presence of the vapors of many organic compounds. They
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 can, for example, be reduced in presence. d "Yhydrocarbons. Aliphatic bides such as paraffins, olefins, acetylenes, hydrocarbons having the formula anH2n-4, on.2n-6, etc ...

   Hy- arogen may be present or absent and the class of products obtained, such as mixtures of oxygenates or, in many cases, oils which by their nature are predominantly hydrocarbons, will vary with the amount of reactive ingredients and with the contact masses and reaction conditions used, and the invention has this advantage that these novel reductions combined

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   can be effected in the desired direction with great efficiency by the incorporation of suitable stabilizer promoters, or stabilizers, into the contact masses.



   Another class of combined reactions is the reduction of oxides of. carbon with or without hydrogen in the presence of aliphatic alcohol vapors such as paraffinic alcohols having the formula CnH2n + 1OH, unsaturated alcohols having the formula CnH2n-1OH, or CnH2n-3OH, etc ...



  Polyvalent alcohols, such as glycol, glycerol, etc., can be reduced in combination with carbon oxides, with or without hydrogen.



   Oxidation products of alcohols, such as, for example, saturated or unsaturated aldehydes and ketones, or oxidation products of polyvalent alcohols such as glycolic aldehydes, glyoxal, glyoxylic acid, oxalic acid, etc. can be used for vapor phase reductions in the presence of carbon and hydrogen oxides. Oxidation products of trivalent alcohols and divided isomeric alcohols may also be employed, of course only when it is possible to obtain the vapors of the compounds without decomposition which is required. do not want.



   Another important class is aliphatic acids. compounds which can be reduced in combination with carbon oxides. These acacia include fatty acids, acids, lactones, polybasic acids, ketone acids, etc. Other various aliphatic carbonyl compounds such as aldehyde alcohols, diketones, triketones, ketones. Oxymethylene, ketone aldehydes, ketone alcohols, etc., can also be combined with carbon oxides and reduced in the presence of the contact masses described above to form many valuable products.

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   In addition to compounds of the aliphatic series which can be reduced with carbon oxides, various compounds of the alicyclic series, such as for example alicyclic compounds such as cycloparaffins, cycloolefins, cyclodiofins, can be combined with oxides. of carbon and reduced. Examples of specific substances of this class are cyclohexane, cyclopentadiene, dicyclopentadiene, etc.

   Of course, alicyclic carbonyl compounds such as cyclohexanal, cyclohexanone, etc., can be used, it being understood in this regard, and throughout this specification, that any compounds containing the. group CO, regardless of whether the oxygen is joined to the carbon by a single or double bond, are included under. the designation of carbonyl compounds.



   Aromatic compounds such as benzene hydrocarbons, mothballs, anthracenes, phenanthra. nes, phenols, aromatic alcohols, aldehydes, ketones and acids can be reduced in the presence of carbon and hydrogen oxides, of course only as the products are capable of volatilization without decomposition. that we do not want.



   Heterocyclic compounds, such as. products containing the furfuran ring, pyrrolic compounds, pyrroliciins, etc., can be reduced with carbon oxides.



     The invention can also be applied to other organic vapor phase reactions such as the decomposition of carbon dioxide, for example, the conversion of polycarboxylic acids or of. their acid anhydrides, monocarboxylic, such as for example the production of benzoic acid starting from phthalic anhydride. Dehydration of all kinds, such as the production of ethers or unsaturated hydrocarbons from alcohols, for example-:,

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 of ethylene starting from ethyl alcohol, can be effectively accomplished.



   A large number of reactions involving molecular associa- tions such as polymerizations and ashes for example, so-called aldehyde aldehyde and crotonization, etc., constitute an important field of catalytic reactions to which the invention invites, nt well. Catalytic halogenations of organic compounds form another field in which the invention can be effectively used. Catalytic "esterifications" form a class of reactions in which long and repeated contact with the catalyst is important and can be effectively carried out using converters of the present invention.



   In the inorganic catalytic field, the synthesis of ammonia and the oxidation of ammonia to nitrogen oxides are effectively accomplished in converter systems having the characteristics of temperature control. of the present invention and, in particular, converters provided with automatic gas cooling, because an advantage of this type of construction is that the heat exchanging elements do not have to be gas-sealed, which makes this type of converter suitable for work under extremely high pressures such as, for example, the synthesis of ammonia under high pressure, organic reductions and hydrogenations such as reduction of carbon oxides, etc.

   Hydrocyanic acid can also be produced catalytically, starting from carbon oxides and ammonia, in converter systems of the invention and the efficient and simple temperature control they provide. is important in that it improves the products and increases the yields in this reaction. Other reactions that we can actually

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 accomplish in. converters of the invention are the catalytic oxidation of sulfur dioxide to sulfur dioxide, the catalytic process for the manufacture of gas with water and the catalytic purification of gases.



   A number of representative catalytic reactions have been listed above; but it goes without saying that the converter systems of the invention are in no way limited to the reactions listed simply by way of example. On the contrary, these converters are applicable to any catalytic vapor phase reaction, either exothermic or endothermic, for although, perhaps, the most important and remarkable field of futility of the invention lies in the class of reactions which are strongly exothermic;

   it is also necessary, in many endothermic reactions, to control the temperature and have exact control of the process, and precise control of the reactive ingredients and the periods of contact with the catalyst, which is an distinguishing factor of the present invention.



   The invention will be described in more detail with reference to the accompanying drawings, which show some typical installations but do not limit the scope of the invention to the features set forth therein. These drawings are for the most part quite schematic since the precise structure and the accessories are, of course, not part of the invention.

   Thus, for example, converters are shown without heat insulation while, in practice, these converters are fully heat insulated; but this feature is irrelevant to the invention and all such well known construction details which are not useful for understanding the features of the invention have been omitted from the drawings for simplicity; nevertheless, it will of course be used by the informed chemical engineer, in installations

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 lations incorporating the principles of the invention, including all suitable or necessary construction details.



   On the drawings:
Fig. 1 is a vertical section through a simple type of pure gas cooled automatic converter with additional uncooled layers of the catalyst;
Fig. 2 is a vertical section through a gas-cooled automatic converter provided with auxiliary temperature equalizing means; Fig. 5 is a horizontal section on 3-3, FIG. 2;
Fig. 4 is a vertical section through a gas-cooled converter, inverted, provided with auxiliary temperature equalizing means;
Fig. 5 is a vertical section through a gas cooled automatic converter provided with auxiliary temperature equalizing means, an internal heat exchanger and a cooler in the recirculation line;

   
Fig. 6 is a vertical section through an automatic gas cooled inverter provided with auxiliary temperature equalizing means and a direct, auxiliary gas introduction;
Freezes. 7 and 8 are details of a variant of auxiliary temperature equalizing means; Fig. is a vertical section through a gas-cooled automatic converter, provided with auxiliary temperature equalizing means and compound heat exchangers;
Fig. 10 is a vertical section through an annular converter provided with auxiliary temperature equalizing means;
Fig. It is a horizontal section along 11-11, Fig.



  10;

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Fig 12 is a section through a semi-automatic, gas-cooled converter provided with auxiliary temperature equalizing means ;.



   Freezes. 13 and 14 are vertical and horizontal sections through the temperature equalizing means shown in FIG. 12;
Fig. 15 is a vertical section through a different arrangement of an automatic, gas-cooled converter with auxiliary temperature equalizing means;
Fig. 16 is a vertical section of a converter of the type shown in FIG. 15, provided with a direct gas inlet;
Fig. 17 is a vertical section of a converter of the type shown in FIG. 15, but provided with an independent device for cooling the temperature equalizing means;

   
Fig. 18 is a vertical section of a converter of the Tentelew type, modified, inverted, provided with means, temperature equalizers
Figs. 19 and 20 are details in vertical and horizontal sections, through the tubes containing the catalyst and the temperature equalizing elements; Fig. 21 is a vertical section of an automatic converter provided with annular heat exchanger elements and temperature equalizing means;
Figs. 22 and 23 are horizontal sections on 22-22 and 23-23, respectively, Fig. 21; Fig. 24 is a vertical section through a gas-cooled annular automatic converter similar to that shown in FIG. 21, but provided with a direct gas introduction;

   
Figs. 25 and 26 are horizontal sections following
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 25-25 and ì6-26; Fig. 24; Fig. 27 is a section of an automatic converter,

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 gas-cooled, with a closed-loop recirculation system containing means for removing reaction products; Fig. 28 is a sectional view of a converter system, showing two automatic, gas-cooled converters in series and a recirculation system provided with means for condensing the liquid reaction products.



   In Fig. 1, a simple automatic converter, gas-cooled, with recirculation is shown; The converter consists of a. casing 1, a top 3, a bottom 4, a gas inlet 5, provided with a valve, a perforated upper plate 2 and a screen 28 on which a layer of catalyst is placed. In the catalyst are embedded tubes 11, closed at one end, which may be provided with perforations at their open upper ends which rise above the surface of the catalyst. Tubes 9, open at both ends, hang from the perforated plate 7 in the tubes 11, extend practically to the dark thereof and are preferably provided with perforations at their lower ends.

   The plate 7 is also provided with loading holes closed by plugs 17 and there are also provided catalyst loading tubes, 16, unloading tubes, 18, and an auxiliary gas inlet manifold, 15. Baffles 32 are placed in the upper part of the converter, above plate 7. Two layers of uncooled catalyst, 46, supported by screens, are placed below the cooled catalyst layer and. baffles 47 are centrally located between the screen 28 and the first uncooled layer, as well as between the two unroasted layers.



  An exhaust pipe 6 starts from the lower part of the converter and a branch pipe 48, controlled by a valve 49, connects to the exhaust pipe and goes to a mixing chamber, 50, which is provided with a pipe. intro

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 duction 51, provided with a valve, and is connected-, by its upper end, with the suction 52 of a blower which delivers, by a pipe. '54 controlled by a valve 53, dada the upper part of the converter. Temperatures in the cooled catalyst layers can be measured by any suitable means such as, for example, a thermoelectric element as indicated at 30.

   In operation, the reactive gases enter through pipe 5, are intimately mixed by baffles 52 then descend through tubes 9, in an indirect heat exchange relation with the aatalyst, reverse their flow at the bottom of the tubes. tubes and rise through the annular space between the tubes 9 and the tubes 11, the gases. trotting during this ascending course, in a direct relation to heat exchange with the catalyst and with the gases. entering through tubes 9. After exiting from the top of tubes 11, the gases can reverse their flow and descend through, the cooled catalyst layer, then through uncooled layers 46, and exit through the pipe 6.

   Part of the gas. having reacted are re-circulated through pipe 48, the chamber. mixing 50, where additional reaction components can be introduced through pipe 51 and, from. the; they are discharged by the fan, through the pipe 54, in the upper part of the converter where they mix with the fresh reactive gases. the proportion of gas delivered. in circulation depends on the setting of valves 49 and 53 and the reactions can be monitored either as. an emergency measure. or regularly by a suitable adjustment of the valves, adjustment which can be done by hand or. be automatic.



   Figs. 2 and 3 show a converter similar to that shown in FIG. 1, but provided with auxiliary heat equalization means and with eutomatic control of recirculation. The same parts bear the

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 same reference figures. The double countercurrent heat exchange elements embedded in the catalyst are all designated the same as those of FIG. 1, but are provided with ¯ port plugs, 56, having holes of varying sizes allowing a relatively greater proportion of gas to pass through the more central heat exchanging elements to compensate for the cooling factor of the envelope of the converter.

   Additionally, heat equalizing elements, 55, are embedded in the catalyst between the dual counterflow heat exchangers, and these elements can be of any suitable construction. and are shown, for simplicity, as closed chambers containing liquiaes of high thermal conductivity, or capable of boiling at temperature. reaction. Examples of such liquids are mercury, mercury alloys or other metals or metal alloys.



   The operation of the converter is similar to that of FIG. 1 with, of course, the additionally improved temperature uniformity achieved by the equalizing means 55. Recirculation is carried out as in FIG. 1, but is shown as automatically regulated by temperature. In addition to the regular thermoelectric elements, 30, an additional thermoelectric element, 58, is placed in a suitable well, in exchange relation. heat with the catalyst, and actuates the: valve, 53 through a suitable relay 57.



  The quantity of. gas. recirculation, which, of course, is determined by the adjustment of valve 53, therefore varies with the temperature in the catalyst and any sudden increases in temperature, for example. in. sensitive and strongly exothermic reactions, will immediately result in re-circulation.

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 tion of a. quantity of gas which antr51ea nominally the ru- ac.ti.cn ", The converter represented in Fig 2 differs slightly, as constiuctLon * from that of alig, '1 in this sense! that it is provided, by example, of a gas introduction pipe, 59, controlled by the valve 58 and entering the pipe.
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 ! as does the re-alr-oulation hose 54.

   This construction performs mixing. wipeu best-, of. gas, costs and. gas- recirculated q # "a. la. Fig, l., Du will also note that the c.onvertàaaÈQE 'et- ceés¯e.nté sum C: gold! sti.- killed by a number of crowns or rings envelope. Use a suitable construction
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 and this variant. is simply il1uatrtva-. of the fact that one can do. vary the Bleoanic coristri2etIon of the converter within wide limits>, as will be taken by the engineer- cihimiata .. '..-, .'- The converter of Figs *.

   S and z aonrient, natuè) 1> - ment, for. reactions more strongly exothermic than those rutules. is intended ealtri de F '... 1. * t one can, for example%, in use for oJ! gait1ic ozda-tioca. strongly exotnermal te.l.es.x, paK-e; x: ejnpl & y 'tta the oxidation' of naphthalene to anhyclrida phthaligue at t.u, t.u.tr: e.des. reactions enumerated in the introduction of this memo Very uniform temperature control is carried out. comma in Fig. l, because the cooling effect of the exchange of. each-
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 their double countercurrent increases in intensity as will the speed of the reactive gases and, within wide limits, - the heat. released in the reaction is directly proportional to the quantity of reactive gases passing through.

   These dual, countercurrent heat exchanger constructions with their extremely high heat transfer have
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 therefore results in a perfectly uniform temperature with wide variations of. velocity of reactive gases, and may be properly considered to have

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 the result is automatic temperature control, which has a. great importance with regard to recirculation which constitutes the main characteristic of the invention.



     Fig. 4 shows an inverted converter, similar in construction to that shown in Figs. 2 and 3. However, in this construction the tubes 11 must, of course, be hearth supported and are, for convenience, shown as resting on the catalyst screen 28.



  This. This figure also represents a significant modification of the auxiliary temperature equalizing means. These bodies can extend above or below the catalysts; in the drawing, they are shown as extending part above and part below.

   This even results in a more uniform control because the elements. Temperature equalizers are exposed either to the reacted gases or to the incoming gases and are therefore cooled or heated by them and, since they transmit their heat vertically, a temperature is obtained. more uniform, which is advantageous * It is naturally clear that, although the figure shows several ways of arranging the temperature equalizing elements, a particular installation will in practice only have one these elements, although the invention is in no way limited to such a construction.



   Fig. 5 shows a somewhat modified type of the converter shown in FIG. 2. The same parts are designated by the same reference numerals. In the converter of FIG. 5, the heat exchange elements. double countercurrent extending below the screen 28, supporting the catalyst, in an enlarged lower part of the converter. The baffles 33 transform this chamber into a heat exchanger, so. than the temperature of the gases circulating in the exchanger elements.

   hot

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 The back flow is modified by contact with the exhaust gases. An additional feature is shown in the form of a means cooler consisting of a corrugated or matched pipe 75, which connects to pipe 54 through pipes 73 and 77, controlled by valves 74 and 76, respectively. The valve 53 is placed between the points or. the pipes 73 and 77 joining the pipe 54- Mayens introductors of fresh gas, are constituted by the pipe 71 which enters the. pipe 5 and is controlled by valve 72. A valve 70 controls the direct introduction of gas into pipe 5.

   The double counterflow heat exchanger elements are provided with port plugs 56, as in Fig. 2.



   The operation of this deconverter system is the same as that of the converter. Fig. However, any desired portion of the recirculated gases can be passed through cooler 75 to reduce their temperature. This is of importance in many organic oxidations where the heat released is so high that. the heat capacity of gases, re-circulated, cooled is essential to maintaining temperature uniformity.

   This type of converter is also of importance in reactions where. it is desirable to cool the final product after it has left the catalyst, which is done, of course, by the extensions of the double countercurrent heat exchange elements.
Fig. 6 shows a converter with the auxiliary introduction of gas directly into the catalyst chamber without passing through the double counter-current heat exchangers. In this converter, fresh gases are introduced, normally, into the pipe 54 through the pipe 61 controlled by the valve 62, or may pass directly through the valve 60. This, of course, is in addition to the possibilities of introduction through the pipe. 51.

   The recirculated gases circulate in

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 double counter-current heat exchangers, as in the devices of the preceding figures, but means are also provided for introducing gases directly into the catalyst chamber without passing through the heat exchangers. These means consist of a separate perforated plate, 2, located above the regular plate 2 and provided with tubes 27 which pass through the sheet 7. are perforated at their lower part and are provided with removable plates 58 which prevent gas streams strike directly at the catalyst and cause them to exit through the perforations and mix with the recirculated and fresh gases which have passed through the countercurrent heat exchangers.

   This auxiliary fresh gas is introduced through the pipe 5 and is distributed through the baffles 26. The introduction can be continued, or it can be used only as an emergency measure to control any elevation. excessive temperature. The operation of the converter is, of course, the same as that of the converters shown in the preceding figures and the temperature equalizers, 55, play the same role. This inverter also shows the application of tubes 9 with perforated lower ends, which allow a more gradual gas exit and prevent excessive cooling of the lower parts of the closed end tubes 11, which prevents the formation of. cold spots in the catalyst.

   One of the tubes 11 is also shown closed at the top and provided with perforations 64 below the level of the catalyst, in order to introduce the gases more evenly, which is advantageous in some reactions and prevents a percentage. excessive. reaction occurs in a whole small zone of catalyst. It will be noted that one can remove the plugs 38 from the tubes 27 and make use of the latter to fill the apparatus with catalyst, instead of the pipe 16. One can obtain by this. method a somewhat more uniform distribution of

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 catalyst and faster filling. It is naturally easy to remove these plugs as they are provided with hooks and can be removed by lifting them up through the tubes 27.



     Figs. 7 and 8 represent types a little. more com-. folded with temperature equalizing means. In fig. 7, the container or body, 55 is for.vu/d'un inner tube. which does not extend quite to the surface of the liquid. and is provided with perforations 66 at its lower end.



   This, of course, results in faster circulation. of liquid because the hot liquid in contact with the walls of the container rises and the cold liquid descends through the pipe 65. Fig. 8 shows a somewhat more complicated construction consisting of an element similar to that shown in FIG. 7 surrounded by a jacket 67 filled with a liquid 68 which, naturally, will have preference. a sufficiently high boiling point to ensure that it remains in a liquid state during the reaction. This latter construction has an advantage when certain liquids are used in the inner vessel to control the temperature by boiling.

   Some of the liquids, such as mercury, are very costly and considerable savings can be made by making use of a liquid jacket, of molten metal for example, which is quite inexpensive and allows a high performance. less amount of expensive material to play the same role. It is, of course, obvious that. any other suitable type of equalizing means can be used. temperature, for example. containers in which a central metal rod is used to replace part of the liquid. This provision results in a considerable saving in. the amount of liquid required.



   It is sometimes desirable. to center the tube 65 exactly in order to ensure a uniform flow and this can be done:

 <Desc / Clms Page number 24>

 by spacer ears 156, shown in Figs. 13 and 14.



   Fig. 9 represents a converter of the same genius design as those of the preceding Figures, but provided with means for introducing two distinct gases into the heat exchanger elements. This is achieved by providing, above the plate 7, a second perforated plate provided with. inner tubes 20 which fit inside the inner tunes 9 and may be provided with port plugs 56 to restrict flow through the peripheral tubes to compensate for the cooling effect of the converter casing. The recirculation means, which are similar to those of the preceding figures and bear the same reference numerals, open into the inlet pipe 23 where the baffles 32 distribute the gas to the various pipes 20.



  Fresh gases can be introduced either into the mixing chamber 50 through the pipe 51 into the pipe 23 'through the valve pipe 22, or into the space between the upper and lower perforated plates from which the gases. descend to tra. towards the annular space delimited by the tubes 20 and the tubes 9. One of the gases can be introduced in one place and another in a different place in order to prevent their mixing until they have reached the bottom tubes closed at end 11. It is desirable, in some instances, to keep the reactive ingredients separated for as long as possible, for example, when it is desirable to prevent premature reaction.

   The temperature equalizing elements 55, of course, play the same role as in the converters of the preceding figures and the converter can be operated as described above.



   Figs. 10 and 11 show a different type of gas cooled converter provided with recirculation means and temperature equalizing means. This converter consists of an envelope 1, a top 3, a bottom

 <Desc / Clms Page number 25>

 an annular top bulkhead 137, a circular bottom bulkhead 138, and concentric cylindrical catalyst retaining screens, 139, connecting the two bulkheads and defining an annular catalyst space. A gas introduction pipe, 140, provided with a valve 141, descends through a central opening existing in the bulkhead
137 and is provided with perforations 142 at its lower end which is some distance above the lower wall 158.

   Concentric cylindrical baffles 143 and 144 hang from bulkhead 137 and rise from bulkhead
138, respectively. The baffle 144 is preferably perforated at its upper end, as indicated by the recirculation system, which is the same as that. shown in the previous figures, bears the same reference numbers and takes gas from the exhaust pipe 6 in order to deliver it, after suitable adjustment, of its composition, through the pipe 53, into the upper space existing between the partition 137 and the top 5 of the converter. Fresh reactive gases can also be introduced through the. pipe 140.



  The recirculated gases descend through the annular space between the pipe 140 and the baffle 145 and mix with the fresh gases exiting the perforations at the bottom of the pipe 140. The gases. are then forced, by the baffles, to follow a tortuous path, being heated by the heat of the baffles and the heat radiating from the inner star-face of the catalyst ring, and then exit through this last by meeting the converter casing where they are rapidly cooled. The path through the catalyst is very short and, as the heat released is quickly transferred by the gas stream to the converter shell, excellent cooling is effected.

   Of course, the top bulkhead, baffles, and bottom bulkhead also help radiate heat to incoming gases.



  Additional temperature control is performed by

 <Desc / Clms Page number 26>

 The temperature equalizing elements 55 which are embedded in the catalyst ring and extend through the partition 137 where their vapor spaces are encountered by the recirculated gas stream and are cooled to a corresponding extent . Depending on the nature of the reaction, the cooling can be carried out mainly by the gases and secondarily by the temperature equalizing means, or vice versa.



   Converters like those of Figs. 10 and 11 are suitable for reactions which occur with short contact times with the catalyst but which are not excessively exothermic. Reactions which result in an unstable product can also be effectively performed since the reaction products immediately encounter the wall of the converter which usually will not be heat insulated and may even be provided with powerful auxiliary cooling means such as fins. drafts or even water currents' sent over it. Thus, the reaction products are almost immediately and suddenly cooled, which prevents their decomposition.

   Of course, in the case of such reactions, recirculation will only be used as an emergency measure, unless the recirculation system is provided with means for removing reaction products.



   Fig. 12 shows a converter of the fentelew type provided with recirculation means and double temperature equalizing means, details of which are shown in Figs. 13 and 14 and have been described above.



   The converter consists of a casing 1, a top 3, a bottom 4 and a perforated partition 145, supporting the catalyst, from which rise the catalyst tubes 146 in which the temperature equalizing means are mounted.



     In the ordinary Tentelew converter, cooling is carried out, by the large radiating surface of the tubes

 <Desc / Clms Page number 27>

 which give up their heat to the incoming gases. This cooling effect is, of course, greatly enhanced by the temperature equalizer elements located in the catalyst tubes and having vapor spaces encountered by cold fresh or recirculated gas streams. This type of converter is not automatically cooled by gas, because the cooler; although it increases with an increase in the speed of the reactive gases, does not increase in proportion to this speed.

   However, for many reactions that do not produce. clearances of. extreme heat, this type of converter is useful and is a very economical type to build. As will be evident, the recirculation system is similar to those shown in the preceding figures and the same parts have the same reference numerals.



   Fig. 15 shows a modified tentelew converter which is transformed into a fully automatic, gas cooled device by placing inverted tubes 147, closed at the end, over the catalyst tubes. These inverted tubes are provided with perforations 146 in their. lower extremities. The incoming gases are thus forced to enter the perforations 148 and rise through the annular space delimited by the catalyst tubes 146 and the tubes closed at the end 147, then reverse their flow after having encountered the upper ends of the tubes. temperature equalizing elements and descend through the catalyst.



    Because of this positively defined flow of. gas and its narrow confinement to the walls of the catalyst tubes, the cooling is fully automatic, as in the case of Fig. 1, and due to the fact that the catalyst is in tubes and therefore the ratio of cooling area to catalyst volume is large, the cooling effect is even more powerful than with

 <Desc / Clms Page number 28>

 converters of the type shown in FIG. 1. The recirculation is, of course, the same as that shown in the previous figures.

   This type of converter can be used for the most intensely exothermic and delicate reaction without its powerful gas cooling together with the auxiliary cooling effect of the temperature equalizing means. It goes without saying that, in converters of the type shown in FIG. 15, as in those of the preceding figures, the temperature equalizing elements can be omitted when the additional cooling and regulating effect which they make possible is not necessary.



   Fig. 16 shows an odiviled converter system, of the type of that shown in fig. 15. This system has, in addition to the regulated gas flow, auxiliary means for directly introducing reactive gases into the catalyst, without passing over the catalyst tubes. This is accomplished by the application of a perforated partition, 149, arranged above the Tentelew tubes and connected with the overturned tubes 147 by hoses 150, the gases being introduced directly through the valve hose 25.

   The temperature equalizing means can be placed as in Fig. 15, arrangement which is indicated by the three tubes on the left of the converter; or they may extend partly or completely through the tubes 150, which will result in very efficient auxiliary cooling since the fresh gases, passing through the narrow annular space between the temperature equalizing elements and the tubes 150 will effectively cool the former.

   The temperature equalizer elements may extend all the way through the catalyst, as shown for the far right tube in the figure, or they may not be vented; go down only partly through the catalyst, like this'

 <Desc / Clms Page number 29>

 is represented by the second tube on the right. The latter arrangement has the advantage that auxiliary cooling is applied only to the portion of catalyst that meets the gases. the most concentrated and where, therefore, the heat release is maximum.

   Any other arrangement of equalizer elements can be made use of. temperature and, of course, in a given converter any arrangement will usually be uniform, with several arrangements being shown in a single converter simply to show a number of variations. The re-represented recirculation system is the same as that described in previous examples. Of course, the temperature equalizing elements can be friendly, as mentioned in connection with the previous figure.



   Fig. 17 shows a further modification of the construction shown in Figures 15 and 16. In this figure, the perforated partition 149 exists, as in Figure 16, and connects to the overturned tubes 147 through the tubes 150; but, instead of introducing gas. additional costs by these tubes, they are closed by packing boxes. 151 and the temperature equalizing elements extend therethrough in a space between the top 3 and the perforated partition 149. This space is provided with an inlet pipe 152 and an outlet pipe 153, all of which are two controlled by suitable valves.

   A stream of cold air, or cold gas, is blown over the vapor spaces of the temperature equalizing elements and results in remarkably efficient auxiliary cooling which may in some cases be more efficient than cooling by gas itself. Of course, the temperature equalizing elements can be of any desired type and be provided with a boiling or non-boiling liquid, or a solid. However, elements with boiling liquid are particularly effective.

 <Desc / Clms Page number 30>

 



   Fig. 18 shows a converter of the modified rentelew type, inverted. In this converter the catalyst tubes 155 hang from a bulkhead 154 placed above them and are provided with removable temperature equalizing elements 156 which are provided with suitable lifting handles and fitted with lugs. 157 resting on the boras of the catalyst tubes. Their lower portion passes through the central hole of catalyst retaining screens 158 which are mounted at the bottom of tubes 155. Construction details of these temperature equalizing elements are shown in Zigs. 19 and 20.

   Lower bulkheads 159 and 160 are provided with perforations and communication pipes 161 while tubes 162, open at their ends, rise from bulkhead 159 and extend between the catalyst tubes. 155. Gases, recirculated or fresh, entering through pipe 163 pass through tubes 162 at the top of the catalyst tubes and then descend around the latter, meeting, at the bottom of the path, the lower ends of the temperature equalizing elements which descend below the catalyst, then, reversing their flow, they rise through the catalyst and exit through the exhaust pipe 6.

   Auxiliary fresh gases can be introduced through the valve pipe 25 and, passing through the tubes 161, directly meet the catalyst without being forced 4 / descend around the catalyst tubes, as is the case for gases introduced through the pipe 153,
Figs. 21 and 22 show a type of converter in which the double countercurrent heat exchange is carried out with a slightly different construction of the heat exchanger element. As in fig. 1, the converter consists of a casing 1, a top 3, a bottom, a gas inlet pipe 5, an outlet pipe 6 and chi-

 <Desc / Clms Page number 31>

 dispensing canes 32.

   Instead of providing in the upper part of the converter a partition from which the automatic heat exchanger elements are suspended, a similar effect is obtained by providing rings, open at one end and of different dimensions, arranged to emerge. - 'limping into each other. Thus, shorter concentric rings 40 are housed within each other with their closed ends resting on a perforated lower support 41 and longer rings 42 are likewise housed within each other with their ends open, which are preferably perforated, fitting into the open ends of the rings 41.

   It is, of course, evident that the center of the rings 40 is occupied by an open tube 45 at one end and that the outer rings, both long and short, are shared by half and use the envelope 1: of the converter as one. of their walls. These "built" rings, that is to say, one wall of which is formed by the casing 1, are designated by 44 and 45, respectively. The catalyst is placed between the rings 40.

   Although. the structure of the converter differs radically from that re: presented in the. Fig. 1, a review of the cut. vertical, Fig. 19, watch. that the gas flow is the same - that is, the gases. arriving through pipe 5 descend into. the annular spaces between the rings 42 reverse the flow and rise between the walls of the rings 42 and the rings 40;

   or else, in the case of the central ring 42, the gases descend through the annular space between this tube and the tube, closed at the end, 43. The first flow is in an indirect relation. heat exchange with the catalyst and, during the reverse flow, the gases passing in a direct heat exchange relationship with the catalyst as well as with the incoming gases, during the downward flow, then during a second reversal the gases pass through the catalyst.



  In other words, in FIG. 21, instead of "a series of elements

 <Desc / Clms Page number 32>

 Heat exchangers, automatic, circular, with double counter-current, all heat exchanger elements except one are annular instead of circular.



  This construction has some advantages for certain converter sizes and, due to the fact that the heat exchange element surface in contact with the catalyst, compared to the volume thereof, is greater.
 EMI32.1
 that with circular elements of the same surface, one can obtain a little more uniform control -J--, the .obtain a little more uniform control of the heat 1 1 ') which is important in well aes.réaa; ions. The temperature equalizing elements 55 are embedded in the catalyst rings, as is evident, and perform their usual role.



   Figs. 24 to 26 represent a converter of the general type of. that shown in Figs. 21 to 23, but provided with means for introducing gases directly into the catalyst without passing through the heat exchanging elements. This introduction is effected by the tubes 27 which extend from the upper rings to. a perforated plate placed in the upper part of the converter. The gases entering through the inlet pipe 5 are distributed by means of the baffles 32, then descend through the pipes 27 directly into the catalyst, meeting the upper parts of the temperature equalizing means, which increases the efficiency. of the latter, especially when they contain liquids which boil at temperatures of. reaction.

   The recirculated gases circulating through the heat exchanging elements and the direct introduction of gas can be seen as a means of emergency control or as a means of introducing cold gas to regulate the reaction.



   Fig. 27 shows a converter in which the principles of automatic heat exchange of the invention are combined with a circuit, partially or completely

 <Desc / Clms Page number 33>

 closed, in which gases are recirculated. The converter is of the type shown in FIG. 6, except that, for the sake of simplicity, no heat equalizing means have been shown. Of course, they can nevertheless be used whenever they are found desirable. In Fig. 27, similar parts of the converter bear the
 EMI33.1
 same reference numbers q, u 'in FIG. / 6.

   The converter offers. two ways of introducing reactive gases either through the heat exchange elements or directly, through pipes 27, on the catalyst. Reactive gases, prin-
 EMI33.2
 cipals, which pass through evaporator 80, which is shown schematically in the form of a surface evaporator, then pass through pipe 79 into the space between the two upper parts of the converter, then descend through the automatic heat exchanger elements and through the catalyst to finally exit through the lower pipe 6 which leads directly to a countercurrent heat exchanger, 81, consisting of a shell 82, tubes 83 and baffles 84.

   The hot exhaust gases pass through the tubas where they are cooled by cooler gases circulating around these tubes, and then pass into the condenser 85 through the pipe 86. This condenser may be of an arrangement. any suitable. The highest boiling point constituents of the gas stream, which constituents in
 EMI33.3
 4 =, s.: =. :: gas ¯..r = ü- .i ;: d. -: fCH! cfesiresS1 s; n4 precipitated and can be removed from the bottom of the condenser through valve pipe 87.

   The permanent gases, or in certain cases also the more volatile constituents which have not undergone the reaction, enter the perforated pipe 88, rise to the circulation pump 52 then pass through the pipe 89 from where a connection 90, provided with a valve 91, leads into a release tower 92 which can advantageously be provided with

 <Desc / Clms Page number 34>

 means to prevent the loss of velatile constituents.



  The branch pipe 93, provided with a valve, opens into the pipe 89 and comes from a source of oxygen or oxidizing gas (not shown). Two branch pipes, 9. and. 95, respectively, run from pipe 89 to the heat exchanger shell. 81 and a valve 96 is provided between the pump 52. and the pipe 94 while a valve 97 is mounted in the pipe 89, between the pipes 94 and 95. The latter pipe extends to the inlet pipe 25 of the. converter and is provided with a valve 98. A branch pipe 99 goes from pipe 95 to the evaporator 80.

   The operation of the converter will be described with respect to the following example which illustrates the application of the principles of this specific modification of the invention to the side chain oxidation of toluol, chlorotoluols or nitrotoluols. :
The converter is filled with a catalyst consisting of 6-8 parts of a freshly prepared mixture of 12% McO3, 78% UO3 and -10% V2O5, with which 100 volumes of granules have been coated. pumice stone, aluminum granules, broken pieces of cellite bricks or fragments of filter stone,. size of a .pea. If necessary, the coating is adhered by means of a potassium-based water glass solution.



   An oxidizing gas consisting of carbon dioxide and oxygen = containing for example 15-20% oxygen = is passed through the toluol 80 evaporator at a temperature sufficient to evaporate the toluol and provide heating. fage of the mixture of reactive gases in the heat exchanger elements at a reaction temperature of 370-420 ° C., the temperature in question being measured after mixing with any gases entering through the tubes 27. Toluol or its substitutes are oxidized in passing through the catalyst either in the corresponding benzylic aldehydes or benzoic acids depending on the speed of the gases, higher speeds favoring,

 <Desc / Clms Page number 35>

 naturally, the production of aldehydes and slower rates, the production of acids.

   The exhaust gases, which contain carbon dioxide, benzyl aldehydes, benzoic acids, unreacted toluol and some unused oxygen, pass through. heat exchanger 81, in condenser 85 which is maintained at a temperature sufficient to precipitate substantially the benzyl aldehydes and benzoic acids but high enough to prevent precipitation of toluol.

   The remaining gases, consisting mainly of carbon dioxide, oxygen and some toluol, rise through pipe 83 into pump '52 where they are discharged through pipe 89 and pass in part or in whole through the heat exchanger 81 through proper adjustment of the valve 97. In the heat exchanger, the gases are heated to the desired temperature and then they pass through pipe 95, pipe 99 and evaporator 80, where additional toluol is evaporated. The loss of oxygen is made up by further quantities of oxygen or, if desired, by air, arriving through the valve pipe 93.

   Proper adjustment of the valve 98 determines the relative proportion of the circulatory gas stream which passes through the toluol evaporator and therefore determines the concentration of toluol in the gas stream, since the gas passing directly from pipe 95 into the top of the converter and thence through the pipes 27 does not take any additional toluol. The speed of circulation of the pump will determine the contact time, the adjustment of valve 97 will determine the temperature at which the gases enter the converter and, therefore, to a large extent, the temperature prevailing in the latter, and the temperature in the converter. By the way of valve 98, the concentration of tolucl will be determined.

   These checks can be done by hand or be automatic or semi-automatic, depending on the particular installation.

 <Desc / Clms Page number 36>

 culière, and ensure absolute control of the temperature ae reaction, the gas concentration had the gas contact time with the catalyst. Without the need to uire it, the oxygen concentration can also be regulated by a suitable adjustment of the valve provided on the pipe 95. It is thus possible to carry out delicate reactions in a simple and safe manner and to maintain the temperature. with a gap of 5-15 C., which is of great importance in these delicate reactions.

   The state of inaction, or of the gases having reacted, can easily be determined by suitable recorders of carbon dioxide and oxygen and, of course, by thermometric elements which are not shown as their location and arrangement will be obvious to the eye. learned chemical engineer. These recording instruments can also be used to actuate the various valves or to vary the speed of the pump so as to control and maintain constant reaction conditions.

   This can be done by means of electrical relays or other devices not shown in the drawings as they will be obvious to the skilled technician, even when oxygen is used as the oxidizing gas there will be a excess carbon dioxide, because even under the most careful operating conditions some total combustion occurs. As the quantity of gas in circulation is increased, part of it can be vented through pipe 90 into the vent tower which is provided with absorbent material for removing material which has not undergone the heat. reaction, entrained with the gases thus discharged.

   In practical operation, it may be desirable to continuously release gas, the amount released being determined by the adjustment of valve 91 which, of course, can be actuated automatically by the differential pressure prevailing in pipe 90 over the valves.

 <Desc / Clms Page number 37>

 both sides of the valve, or by any other suitable means which will be obvious to the skilled chemical engineer. When air is used as a medium. oxidizer, there will be a very rapid accumulation of inert gases because four times as much nitrogen is introduced as oxygen. In this case, of course, one will have to increase the clearance and make it, preferably, continuous.

   The choice between oxygen and air-, gas cornrna. oxidizing agent, is determined to a large extent by economic factors such as the loss of toluol in the release, even when absorbent means are provided, the cost of oxygen, and the like. In any given installation, the informed chemical engineer will choose the conditions which are the most economical for the installation in accordance with the principles of the present invention which is, of course, not limited to the use of a gas. any particular oxidizer.



   Although it is advantageous in many cases to operate with a complete closed system, that is, a system in which all, or substantially all, of the gases leaving the condenser are recirculated. , this is not essential and, in particular when an inexpensive oxidant such as air is used, a semi-closed system, in which part of the gases are continuously evolved or discharged and where gases Fresh oxidants are added in an amount larger than that required to oxidize organic material in a single cycle, is very satisfactory.

   This semi-closed system is somewhat more efficient when the reaction is pushed closer to completion, or when a very volatile starting material, such as toluol, is not present, as continuous release is less desirable. when large quantities of volatile matter which has not undergone the reaction must be separated from the gases sent for off-gas. Natural- Bond, the same installation can be used sometimes as a closed system and sometimes as a semi-closed system in order to

 <Desc / Clms Page number 38>

 satisfy varying reaction conuitians.



   Fig. 28 shows a particularly well-known arrangement for the production of aniline starting from nitrobendin, or similar liquid amino compounds starting from liquid or easily liquefied nitro compounds. Two converters are provided, shown as "A" and "B", consisting of an outer shell 101-A and 101-B, a lower chamber 102-A and 102-B, an upper chamber -
103-A and 103-B, a catalyst carrier chipmunk 104-A and 104-P of double countercurrent tubular heat exchange elements, such as those shown in FIG.

   l, having outer tubes 105-A and 105-B and inner tubes 106-il and
106-B and a central evaporator tube 107-A and l07-B connecting the upper and lower chambers. In these evaporator tubes extend valve spray hoses, 108-il and 108-B coming from reservoirs with nitrobenzine 109-A and 109-B,
It is evident that the top of the lower space, the evaporator tube and the catalyst screen define an annular chamber 110-A and 110-B. From chamber 110-B a valve pipe 111 goes to tubular heat exchanger 112, consisting of a casing 113, tubes 114 and baffles 115.

   Pipe 111 is connected with one end of the heat exchanger and the gases passing through this pipe then pass through the tubes of the heat exchanger, from where they pass through the liquid condenser. 116, which is conventionally shown as a coil which is immersed in a suitable cooling bath contained in reservoir 117 and ultimately terminates at manifold 118. The condensate can be removed from this neck. - drive through the valve pipe 119 and the non-condensed material leaves the upper part through the pipe 120 to go to a pump 121 for which the valve pipe 122 constitutes. a bypass' or detour or bypass duct.

   A 123 valve hose comes from a source of hydrogen or reducing gas

 <Desc / Clms Page number 39>

 (not shown), while what represses. the pump passes through pipe 124 into the casing of exchanger 112, circulating around the tubes, and exits through pipe 125 which terminates in a heating coil 126, shown. conventionally in the form of a coil provided with a heating bath contained in a suitable container 127. A valve release pipe, 128, provided with a suitable release tower 129, connects to pipe 125 and a valve pipe 130 constitutes a bypass or bypass duct for the heating coil.

   From the outlet end of the heater, where. the pipe 130 joins therefrom two valve pipes, 131 and 138, going respectively to the lower compartments 102-A and 102-B. A valve pipe. 135 connects the lower space 102-A with the annulus 110-B and a similar valve pipe, 134, connects the lower space 102-B with the annulus 110-A. A valve pipe 135 also connects the annular space 110-A with the pipe 111 terminating in the heat exchanger 112.



   In operation, the reducing gases entering through pipe 123 are returned by the pump: 121 through the heat exchanger, pipe 125, heater 126, or bypass 130, depending on the adjustment of the. valve, then, by closing the valve of the pipe 132 and the opening of the valve of the pipe 131, they pass through the latter into the space 102-A from where they rise in the evaporator tube 107- A against the current to the sprayed nitro benzine descending from tank 109-A, the heat contained in the gases. being sufficient to evaporate the nitrobenzine.

   The vapor and reducing gas mixtures then pass through the heat exchange elements to. dual-current 106-A and 106-A where. they are heated further and, from there, to. through the. catelyseur, in the annular chamber 110-A then, by the. pipe 134 (the valve of pipe 135 having been closed) in the lower chamber

 <Desc / Clms Page number 40>

 higher 102-B;

   from there they pass into the evaporator tube
109-B where, if desired, more can be sprayed with. nitrobenzine but where ordinarily the spray hose valve 108-B will be closed, and they then pass through the heat exchanging elements of converter B @, descend through the catalyst into annular chamber 110-B and exit through the pipe 111 and through the tubes of the heat exchanger 112 where they serve to heat, the incoming gases and reducers and are themselves cooled.



  Further cooling occurs in coil 116 which results in aniline condensation. The aniline drops to the bottom of the collecting tank 118 and can be withdrawn through the valve pipe 119 while the unreacted gases, with proper adjustment of their hydrogen concentration, begin the cycle again.



   - When desired, some gas can be released through the vent pipe 12: 8 and vent tower 129 and the amount of heat can be varied. coil 126 by varying the proportion of gases passing through bypass 130. If desired, the flow through the converters can be reversed by a suitable adjustment of the valves, as will be evident to an experienced chemical engineer , the gases passing through pipe 132 into space 10-B, then rising through evaporator tube 107-B, where they meet the sprayed nitrobenzine descending from tank 109-B,

   for aescenare en - suite through the heat exchanger elements and the catalyst of converter "B" in the annular space 110-B, then through the pipe 133 to the lower space 102-A, back up through the tube evaporator 107-A, with or without further addition of nitrobenzine, back down through the heat exchanger elements and through the converter catalyst, "A" into the annular chamber 110-A and pass from there through the pipes 135 and 111 ,. in the heat exchanger 112.

 <Desc / Clms Page number 41>

 



   If only one converter is to be used at a time, this can be done by suitable adjustment of the valves. Thus, for example, the converter "A" can be made use of in closing them. valves, pipes 132, 133 and 134. The gases, after. having passed through converter "A", then go directly, through pipe 135, to the heat exchanger. You can, in a similar way, use the converter "B" alone by closing the valves of the pipes 131, 133, 134 and 135. The gases, after. having passed through converter "3" then enter the heat exchanger through pipe 111.



   A two converter system, such as that shown, with means for evaporating nitrobenzine or other liquid to be reduced, allows very exact control. temperature and, at the same. time, keep. at the highest degree. heat of reaction. We can also do; varying the concentration of the reactant gases by varying, for example, lets, amounts of nitrobenzine introduced into the two converters in series.

   Different temperatures, or: conditions of. Different catalyst may also exist in the two converters, which makes. the very own system perform reactions that must be done. in stages such as, for example, the synthesis of. methanol or motor fuels, or the production of benzyl aldehyde and benzyl alcohol from phthalic anhydride through the phthalide stage, etc.



   The two converter system is also. effective in the case where it is desired to be able to repair one of the converters without stopping the process, since one or the other of the converters can be isolated at will. In cases where catalysts deteriorate with use., it is also possible to reverse the direction of the flow. as described above, when it may be desirable. The converters shown in Fig. 28 are only examples.

 <Desc / Clms Page number 42>

 ples and, of course, all other types of gas-cooled converters. shown in the first figures and described above can be used whenever their particular characteristics make them desirable.



    When obtaining a solid reaction product, it is also possible to dispense with the type of condenser shown, which is only necessary when the reaction product is a liquid.

** ATTENTION ** end of DESC field can contain start of CLMS **.


    

Claims (1)

Freezes. 27 and 28 have been described with regard to specific reactions, for which they are well suited, in order to make the operation more clear and concrete. Of course, however, it goes without saying that these types of converters can be used for all other reactions requiring the type of control they give. Of course, also, recirculation systems with partial or total separation of products which have undergone the reaction, such as, for example, those shown in FIGS. 27 and: 8 can be applied to converters shown in these other figures. As was specified above, super.flus accessories have been eliminated and, for simplicity, the first figures showing recirculation have been drawn without separating systems; but how to incorporate suitable separator systems into recirculation systems, or in place of the schematically indicated aispositiis of early systems, will be obvious to the skilled chemical engineer and all practitioners. modifications of this kind come, of course, within the scope of the invention. In summary, the invention comprises: An apparatus for vapor phase catalytic reactions, essentially comprising a gas-cooled converter. reaction, such as a converter in which the cooling effect increases rapidly with <Desc / Clms Page number 43> crossing. in the speed of said gases and. preference in proportion to this increase, for example: , a converter provided with double countercurrent heat exchange elements, with or without associated temperature equalizing elements with, c the contact mass in. the converter and consisting of bodies. of high thermal conductivity and high heat capacity, such as. of. body in @ ... metal or, containing compartments. liquids which boil at about, slightly above or above the reaction temperature, and means for recirculating to. minus one. part of the reacted gases coming from the converter, the recirculation system preferably being provided with means for removing reaction products, such as for example condensers, for products of low volatility, and means for introducing reactive material into the gases. put back into circulation, with or. without. means for adjusting the temperature of the recirculated gas stream, said apparatus furthermore being able to be characterized in that: a) All reacted gases pass through a recirculation system which is provided with condensation means for non-volatile ingredients, with or without release means for gaseous reaction products. permanently, or diluents thereof, said releasing means preferably being provided with a suitable absorption system to prevent the loss of volatile material which has not undergone or has undergone the reaction, and that b) the proportion of gas. put back into circulation and (on} <Desc / Clms Page number 44> the speed of these varies automatically according to the reaction temperature.