US2143009A - Shielding of converters - Google Patents

Description

Jan. 10, 1939. E. J. HOUDRY 0 SHIELDING OF CONVERTERS Filed May 13, 1936 2 Sheets-Sheet 1 III/1,,

1.. r: is? fi/ A 9 S 3 Zia- INVENTOR EuoENEdHouoRY ATTORNEY Jan. 10, 1939. E, J. HOUDRY SHIELDING OF CONVERTERS Filed May 13, 1936 2 Sheets-Sheet 2 INVENTOR EuoENEdHoumY BY ATTORNEY Patented Jan. 10, 1939 PATENT OFFICE SHIELDING OF CONVERTERS Eugene J. Houdry, Rosemont, Pa., assignor to Houdry ProcessCorporation, Dover, DeL, a corporation of Delaware Application May 13, 1936, Serial No. 79,406

13 Claims.

The present invention relates to the operation and control of reactions, including those resulting from or involving the use of contact masses,

whether catalytically active or substantially inert. It has special application to the type of operations where fluids are fed to a reaction chamber of a converter at a temperature which is substantially or widely difierent from the desired reaction temperature, as, for example,v

where it is desired to oifset or compensate for the endothermic or exothermic character of the reaction by supplying the reactants at a temperature substantially above or below that of the reaction. In converters or similar apparatus employed to carry out such operations, portions of the apparatus with which the relatively cold (or relatively hot) fluid comes in contact, prior to entering the reaction chamber, tends to assume a temperature widely or substantially diflerent from those portions of the apparatus which surround or are located in the reaction zone and therefore those parts or intervening parts of the apparatus normally sufier undesirable or severe internal stresses. In its general relation to the control of reactions, particularly those utilizing a contact mass to promote, enter into, or in any way eflect reactions such as the synthesis of ammonia, the production of sulphuric anhydride, the treatment or transformation of hydrocarbons, etc., the present invention may be considered as an improvement upon or further development of Patent No. 1,987,904 issued to me on January 15, 1935.

In so far as the present invention relates to minimizing or preventing radiant heat exchange between a tube sheet or partition bounding the reaction chamber and other parts of the converter, such as the other walls of a maniiolding chamber, it may be considered as a further development of the copen'ding application of Thomas B. Prickett, Serial No. 14,068, filed April 1, 1935 (Patent No. 2,102,644, issued December 21, 1937). However, it will be seen that the present invention, as distinguished from the copending application, does not permit more than a very small percentage of the introduced fluid to sweep over the tube sheet or'equivalent before entering the reaction chamber or distributing conduits which extend thereinto; also that the present invention provides heat bellies along or in spaced relation with the casing walls adjacent and opposite such tube sheetor the like or with other walls or surfaces with which relatively cold (or hot) fluids may come in contact before entering the reaction chamber.

It is a primary object of this invention to devise improved ways and means to minimize or restrict heat exchange between fluids and parts of a reaction or conversion apparatus before such fluids reach parts of the apparatus where it is desired to have heat exchange occur, thereby to reduce or eliminate substantial or deleterious thermal stresses which commonly occur in the casing walls or other elements of reaction apparatus. A further object is to employ bathing means which do not possess the undesirable characteristics of certain conventional heat insulating materials and do not tend to absorb large quantities of the fluid employed. Another object is to provide suitable mounting means which permit convenient removal and replacement of shielding members. Other objects and advantages will be apparent from the detailed description which follows and from the specification as a whole.

An understanding of the invention may be facilitated by reference to the illustrative embodiments thereof shown in the accompanying drawings in which:

Fig. 1 is an elevational view, partly in section, of a converter or reaction chamber having the central portion thereof cut away and having baflles or shields in both manifolding chambers;

Fig. 2 shows the lower end of a converter generally of the type shown in Fig. 1 having rather similar baflles but having a jacketed chamber surrounding the manifolding chamber;

Fig. 3 shows in somewhat enlarged scale the lower end of a converter similar to that shown in Fig. 1 but having multiple baflles shielding certain portions of the surfaces or walls which bound the maniiolding chamber;

Fig. 4 is an enlarged detail view in section of a portion of the apparatus shown in Fig. 1;

Fig. 5 shows an enlarged detail view in section of a portion of the lower tube sheet of Fig. 1 with a modified construction of baiiies, permitting convenient assembly of the baifles which shield the beams supporting the tube sheet;

Fig. 6 shows in detail an exemplary form which the lower ends of the baflies, shown in the lower manifolding chambers of Fig. 1 or 3, may take;

Fig, 7 is a developed section of a baflle plate of the type shown in Fig. 3, having slots therein to permit rapid assembly thereof on or adjacent surfaces which it is desired to shield;

Fig. 8 shows an enlarged detail view of a grooved post or stud of the type employed in Fig. 3 and a broken away section of the casing to which it is attached, such post being adapted for use with a slotted sectional tube sheet, such as shown in Fig. 7; I

Fig. 9 is an enlarged detail view in section taken on line -11 of Fig. 7 to further illustrate the slots of Fig. 7; and

Fig. 10 shows in cross-section a modified form of the ends of the baifies which are parallel with the tube sheet in Fig. 3.

Referring more in detail to the drawings, in the several figures of which like reference char= acters denote similar parts, I is a converter casing having a reaction chamber 2 bounded at either end by manifolding chambers 3 and 4. The lower manifolding chamber 3 is separated from the reaction chamber by the tube sheet and the upper manifolding chamber is separated therefrom by tube sheet 6. Within the reaction chamber perforated conduits I, which by way of illustration may be considered as inlet conduits, and perforated conduits 8, which may be considered as outlet conduits, are embedded in contact mass 3, which latter may consist of any known or desired contact materials, including silicates of alumina or clayey materials, e. g., blends of silica and alumina in fragmentary or preferably in molded form and with or without the addition of other active components such as metals and metallic compounds. Baiiles I0 and II line the inner walls of manifol-zling chamber 3 in Fig. l. and are in spaced relation with such walls. These baflle plates are preferably made of non-absorbent, corrosion-resistant material such as chrome steel or other metallic or durable material. Baiiles III are suitably fastened in spaced relation to the walls of easing I as by fastening means or studs II, which have shoulders or sleeves, and which are tapped into, welded or otherwise fastened thereto. The baflles are maintained in spaced relation with the wall of easing I by combined spacer and fastening means or spacer blocks I3, which may be fastened to the bafiles but not to the walls of easing I. The tube sheet baflles i I are held in place, in spaced relation with tube sheet 5, by nuts I4 which are screwed onto the ends of the inserts or extensions to conduits Sleeves I5, which surround each of such inserts, maintain baiiles I I in desired spaced relation with the tube sheet.

Bailles III in Fig. 1 are made up in sections which overlap on the studs I2 or spacer blocks I3, as shown in enlarged detail in Fig. 4. These joints may be held firmly together by nuts which engage suitable screw threads on the studs or inserts which pass through the spacer blocks, as shown in Fig. 1 but omitted for the sake of clarity in the detailed showing in Fig. 4.

Bellies I Ila and Ho which surround the walls of upper manifolding chamber 4 are generally similar to those which surround the walls of lower manifolding chamber 3. Baiiles Illa are ordinarily fastened to the casing walls at several points by studs I!!! which are tapped into such wws while baiiie Ila is supported by sleeves I5a which surround the inserts of conduits 8 and rest against tube sheet 6, nuts' I 6 being applied to the threaded ends of the inserts of conduits 8 to hold the parts in place.

In the operation of the apparatus reactants may be admitted to one of the manifolding chambers at a temperature above that of the reaction, if the latter is endothermic, or at a temperature very much below that of the reaction, if the latter is strongly exothermic. In either instance the shell of the converter and the partitions or tube sheets are to be protected from sharp temperature changes to avoid distortion and rupture of the apparatus. In some cases, as in the treatment and conversion of hydrocarbons, alternative endothermic and exothermic reactions take place due to the accumulation of a carbonaceous or other burnable deposit on the catalyst (during the on stream or endothermic reaction) which is removed by a subsequent regeneration by oxidation which is a strongly exothermic reaction. The on stream reaction temperatures are normally below regeneration temperatures and at times the difference is quite wide as from 150 to 500 F. and it is desirable to use cool reactants to control the exothermic reaction.

When reactants are introduced into manifolding chamber 3, they pass upwardly through inserts Ia of the double or nested conduits I and then emerge through perforations 'Ip into contact with mass 9. The fluid migrates through mass 9 to perforations 8p in conduits 8 and leaves the reaction chamber through inserts to which empty into manifolding chamber 4, from which latter the products of reaction may leave the converter. When cool reactants or regenerating fluid pass up through insert Ia of inlet conduits l and then pass downwardly through the annular space between insert 1a and outer perforated member ID, heat exchange is eifected with the surrounding mass which keeps the' latter from rising to too high a temperature while the regeneration medium is brought up to such a temperature that the desired combustion or regeneration will be sustained in the reaction chamber 2. It is de= sirable that the heating up of the regeneration medium, which preferably takes place during its passage through the conduits I, be accomplished in such a way that the regeneration medium will not cause any incidental deleterious cooling of the tube sheet 5 or other walls of the manifolding chamber 3. When casing I of the converter is made in one continuous piece, and special provision is not made for preventing cooling within the manifolding chamber 3, large stresses are set up in the casing, particularly just at or below the tube sheet 5, which tend to cause distortion or failure thereof. Bailies III of Fig. 1 counteract this cooling effect and, supplemented by insulation S which surrounds the exterior of the converter, tend to keep the walls of the latter, particularly portions at or below the tube sheet 5, up to at least approximately the temperature of the walls thereof above such tube sheet. Baflles II, which extend along and adjacent to the tube sheet I and around supporting beams I6 prevent undesirable cooling of the tube sheet, thereby keeping the contact mass 3 which is adjacent such tube sheet from getting cooled below that of the main body of the mass and protecting supporting beams I6 from being cooled down to, for example, atmospheric temperature on their lower surface whereas the top of the beam may be at a temperature of approximately 800 or 900 F. Such temperature differences between the top and the bottom of a beam sets up tremendous stresses and tends to cause the beam to bow upwardly. thus dislocating the tube sheet and the conduits within the reaction chamber.

The principal purpose of bailles Illa and Ho, 1. e. of baffles in both manifolding chambers, is to make the converter reversible inoperation; that is, to permit relatively cool fluid to be introduced into manifolding chamber 4 whereas products of regeneration or the like maybe withdrawn through manifolding chamber 3, as well as according to the manner described above.

accumulate behind the baffles. Instead of having I openings or serrated edges, the baffles may be slightly spaced from the casing. I y

In Fig. 2 the manifold chamber 3a is provided with a fluid-tight jacket is therearound. Heat 15 exchange fluid may be introduced into the jacketed chamber through conduit i9 and withdrawn therefrom through conduit 20, to supplement the action of baflies which are located within the manifolding chamber adjacent its walls. In this 20 embodiment, the baffles comprise continuous strips extending from the top of the manifolding chamber downwardly throughout the whole remaining extent of the casing walls thereof and along the neck 2i, to project between the flanges 25 Zia and 22, thereby extending the zone of protection. The ends of the baiiies are made thinner than the gasket between the flanges 2Ia. and 22 so as not to interfere at all with the making of a fluid-tight joint and are provided with small 30 openings ill) to permit a slight amount of circulation behind the baiiies and to permit drainage of fiuid therefrom. Baflies llb adjacent tube sheet 51; are held in spaced relation therewith by studs or posts 23 which are tapped into the tube sheet 35 and which may be threaded at their outer ends to receive nuts 24.

In Fig. 3 a multiple heat bafiiing arrangement is shown for the parts of casing I, which need the most protection, namely tube sheet 50 and the 40 supports therefor including beams I60. Sectional bames lilo extend along the whole side of the casing wall of the manifolding chamber to a point adjacent neck 280 of the converter, baffles ind extend half or two-thirdsof the way down such casing, while baffles we extend over only a short section of the upper portions of such casing wall near the tube sheet c. Bailies Hc, lid, and He are joined at their peripheries or edges with the upper ends of bafiies I00, Md and 50 we, respectively, to form approximately iiuidtight joints. A special form of such joints is illustrated in cross-section on an enlarged scale in Fig. which shows slots or grooves on baiiles Me, i id and 8 ie into which the upper ends of the 55 baffles 560, Md, or we may fit.

When a type of treating operation is contemplated which causes deterioration of the heat baiiies and requires periodic replacement of the same, or when it is desired to facilitate the assembly of heat baflles within a. converter, there is often an advantage to be gained by having the walls which are to be shielded provided with suitably demountable or slip connections. These may comprise posts 25 (Fig. 8) having grooves 65 250, or the equivalent, rigidly fastened to the wall to be shielded, for example the casing I. Such" posts will be disposed in regular arrangement to correspond with the spacing of slots such as 26 in baffle 21 shown in Fig. 7. Bailies iilc, mad and llle in Fig. 3 may be like or similar to the developed section shown in Fig. 7. Post 25 is provided with three grooves as shown, making it suitable for use in the multiple baiiies disclosed in Fig. 3. A baflle section 21 may be mounted by lining up the large portions 26a of the slots 26 with the top of posts 25, pushing baffle 21 down over the posts until the appropriate depressions or grooves 25a. are reached and then moving the is to move each section slightly to the right or left, depending on which way the small parts of slots 26 extend and lifting the section free of posts 25.

In all of the figures of the drawings the spacing of bafiie plates from the surfaces to be shielded and the spacing of bafiles from each other are exaggerated for the sake of emphasis. In practice, only a very slight spacing is required so long as actual contact is avoided. This spacing may be of the order of a A," or an inch, for example, depending upon the accuracy with which the battle is held in spaced relation with the surface to be shielded.

What I claim is:

1. Apparatus for effecting chemical reactions .which comprises a casing providing a reaction chamber extending over substantially the entire area of said partition and over that of at least those portions of the casing walls thereof located nearer to said partition, means holding said plates in spaced relation to said partition and said portions of said casing walls, thereby to shield said portions and partition against fluctuating temperatures of fluids passed through said manifolding chamber, and tubular means extending between said partition and baffle plate or plates adjacent thereto, in registering relation with the perforations in said partition and with oppositely located perforations in said baille plate, so as to permit the passage of fluid between said manifolding chamber and said reaction chamber without circulation thereof in substantial proportion through the spaces between said partition and the bafile plate or plates spaced in adjacent relation therewith.

2. Apparatus for effecting chemical reactions which comprises a casing providing a reaction chamber adapted to contain a contact or catalytic mass and a manifolding chamber adjacent one end of said reaction chamber, a perforated partition extending across said casing to separate said reaction chamber from said manifolding chamber, bafiie plates of non-absorbent material within said manifolding chamber covering portions of the casing walls thereof adjacent said reaction chamber with a multiple layer of heat bafiies, means spacing said plates or baffles from the portions of said walls which they shield and from each other, and less baiiles covering other portions of said casing walls of said manifolding chambers which are more remotely located from said reaction chamber, so that substantially all portions of said casing walls equidistant from said partition are substantially equally shielded and so as to shield most the said portions of the casing walls of said manifolding chamber which are adjacent said reaction chamber against fluctuations in the temperatures of fluids passed through said manifolding chamber, the edges of said baflies being fastened so as approximately 3. Apparatus for effecting chemical reactions which comprises a casing providing a reaction chamber and a manifolding chamber adjacent one end of said reaction chamber, a perforated partition extending across said casing to separate said reaction chamber from said manifolding chamber, baflie plates within said manifolding chamber located adjacent butin spaced relation with the walls thereof to shield substantially the entire area of said partition and of the casing walls adjacent thereto against fluids of widely different temperatures passed through said manifolding chamber, said bafiie plates being relatively arranged so as approximately to exclude the circulation therebehind of fluid passing through the manifolding chamber, a jacket surrounding said casing along said manifolding chamber, terminating adjacent the end of said manifolding chamber bounded by said partition, to form a confined passageway for heat exchange fluid surrounding said manifolding chamber, inlet and outlet ducts communicating through said jacket to permit circulation of fluid throughsaid passageway, and tubular means extending between the aforesaid partition and baffle plate or plates adjacent thereto, inregistering relation with the perforations in said partition and with oppositely located perforations or openings in the battle plates, so as to permit the passage of fluid between said manifolding chamber and said reaction chamber while approximately excluding the circulation thereof through the space between said partition and the baiiie plate or plates spaced in adjacent relation therewith.

4. In apparatus for effecting chemical reactions which comprises a casing providing a reaction chamber adapted to contain a contact mass and a manifolding chamber adjacent each end of said reaction chamber, one of said manifolding chambers being adapted to serve as an inlet manifold and the other as anoutlet manifold, and perforated partitions separating each of said manifolding chambers from the adjacent reaction chamber, that improvement which comprises plate baffles of non-absorbent material located within each of said manifolding chambers and extending over and shielding substantially the entire surface of the perforated partition and at least those portions of the casing wall nearest to said partition in each of said inlet and outlet manifolding chambers, said bailles being located adjacent to but inspaced relation with the partition and walls which they shield and being constructed so as approximately to exclude fluids passing through each of the manifolding chambers from circulating through the spaces between the said baifles and the adjacent surfaces which they shield, thereby to minimize stresses insaid casing walls and partitions by avoiding sharp fluctuations in the temperatures thereof and to prevent undue cooling or temperature change of adjacent sections of said reaction chamber, and tubular means extending between each of the said partitions and the respective bailies adjacent thereto, in registering relation with the perforations in each of said partitions and with oppositely located perforations or openings in the adjacent bailies so as to provide for the passage of fluid between each of said manifolding chambers and said reaction chamber without circulation thereof in large proportion through the spaces between either of said partitions and the respective bafiles shielding the same.

5. Apparatus for effecting chemical reactions which comprises a casing providing a reaction chamber and a manifolding chamber adjacent one end of said reaction chamber, a perforated partition extending across said casing to separate said reaction chamber from said manifolding chamber, baiile plates within said manifolding chamber and located adjacent to but in spaced relation with the walls thereof to shield said walls against temperature changes from fluids of widely different temperatures passed through said manifolding chamber, said baliie plates being fltted together with respect to the walls of said manifolding chamber and to each other so as to provide a substantially continuous shield over said walls and so as approximately to exclude fluids from circulating past the edges thereof through the space between said baille plates and the said walls which they shield, tubular means extendingbetween said partition and the baille plate or plates adjacent thereto, in registering relation with perforations in said partition and with oppositely located perforations or openings through said baflle plate or plates, so as to permit the passage of fluid between said manifolding chamber and said reaction chamber without cir culation thereof in substantial proportion through the space between said partition and the baffle plate or plates spaced in adjacent relation therewith, and means including relatively small perforations or openings at spaced intervals in said baille plates to permit a small proportion of the order of 1% to 2% of the fluid passing through said manifolding chamber to circulate through the space between said plates and the surfaces which they shield.

6. Apparatus for effecting chemical reactions which comprises an upright casing providing a reaction chamber and a manifolding chamber adjacent the lower end of said reaction chamber, a partition having perforations or openings therein extending across said casing to separate said reaction chamber from said manifolding chamber, baiiles lining substantially the entire casing walls of said manifolding chamber, fastening means for holding said baffles firmly to said casing walls at a plurality of points located adjacent the upper end of said manifolding chamber, and combined spacer and fastening means adapted to join adjacent sections of said heat bafiies in ap-' proximately fluid-tight engagement and maintain them in spaced relation to said casing walls.

7. A converter, a perforated partition therein dividing the interior into a reaction chamber adapted to contain a bed of contact or catalytic material and an end manifolding chamber, baiile plates mounted on the inside of the converter walls of said manifolding chamber, other baille plates mounted upon the manifolding'chamber side of said partition, the adjoining ends of all said baille plates interfitting or overlapping in such manner as to provide a substantially continuous shield, which is held in spaced relation to the walls and partition defining said manifolding chamber, and a plurality of tubular means extending from the perforationsor openings in said partition to said other baffle plates, in registering relation with perforations or openings in the latter, so as to permit the passage of fluid between said manifolding chamber and said reaction chamber without circulation thereof in substantial proportion through the spaces between said partition and the respective baille plate or plates shielding the same. 8. A converter, a perforated partition therei dividing the interior into a reaction chamber adapted to contain a bed of contact or catalytic material and an end manifolding chamber, members extending into said manifolding chamber from the converter walls and from said partition, baffle plates mounted upon said members in spaced superposed relation in such arrangement as to form a continuous shield about the interior of said manifolding chamber, cooperating means on said members and on said plates permitting convenient detachment of the latter for removal or replacement, and tubular means extending from the perforations in said partition to the adjacent bailie plate or plates, in registering relation with perforations or openings in the latter, so as to permit the passage of fluid between said manifolding chamber and said reaction chamber without the circulation thereof in substantial proportion through the spaces between said partition and the respective baflie plate or plates shielding the same.

9. Apparatus for effecting chemical reactions which comprises a casing providing a reaction chamber-and a manifolding chamber adjacent one end of said reaction chamber, a perforated partition extending across said casing to separate said reaction chamber from said manifolding chamber, posts fastened to and extending inwardly from the walls of said manifolding chamber, a series of bafiies, of heat resistant and non-absorbent material, mounted on said posts within said manifolding chamber adjacent the walls thereof, and extending over substantially the whole area of the walls thereof including that of the said perforated partition, to shield the same against fluids of widely different temperatures passed-through said manifolding chamber, said baflies being made up of a plurality of sections, fitted together and with respect to the said walls of saidmanifolding chamber so as to restrict circulation of fluid through the space between said baiiles and the surfaces of said walls which they shield, each baffle being maintained inadjacent but spaced relation to the surfaces of said walls which it shields, and tubular means extending between said partition and bafiles adjacent thereto, in registering relation with the perforations in said partition and with oppositely located perforations in said baflles, so as to permit the passage of fluid between said manifolding chamber and said reaction chamber without the passage thereof in substantial proportion through the space between said partitionand the baflie plate or plates spaced in adjacent relation therewith.

10. Apparatus for effecting chemical reactions which comprises an upright casing providing a reaction chamber and a manifolding chamber adjacent the lower end of said reaction chamber, a partition having perforations or openings therein extending across said casing to separate said reaction chamber from said manifolding chamber, bafiles lining the casing walls of said manifolding chamber, fastening means for holding said bafiles firmly to said casing walls at a plurality of pointslocated adjacent the upper end of said manifolding chamber, combined spacer and fastening means adapted tojoin adjacent sections of said heat bafiies in approximately fluid-tight engagement and maintain them in spaced relation to said casing, bafiies shielding substantially the entire surface of said partition and held in spaced relation therewith, all of said baflles being arranged with relation to each other and to the surfaces which they shield so as to restrict circulation of fluid in the space between them and the adjacent walls of said manifolding chamber which they shield, and tubular means extending from the perforations in said partition to the adjacent baflies in registering relation with openings in the latter, so as to permit the passage of fluid between said manifolding chamber and said reaction chamber without circulation thereof in substantial proportion through the spaces between said partition and the respective baffles shielding the same.

11. A converter, a perforated partition therein dividing the interior into a reaction chamber adapted to contain a bed of contact or catalytic material and an end manifolding chamber, members extending into said manifolding chamber from the converter walls and from said partition, baffle plates detachably mounted upon said members in such manner as to form a continuous shield about the interior of said manifolding chamber, at least a portion of said members being in theform of posts or studs with grooves at spaced intervals and certain of said plates having slots to provide slip and locking connections with said posts and to provide for mounting said plates in spaced superposition, and a plurality of perforated conduits extending within said reaction chamber, said conduits each having an open end communicating with said manifolding chamber through the perforations of said partition, said open ends of said conduits extending beyond said partition and through corresponding openings in said baflle plates adjacent thereto, so that fluids passing between said manifolding chamber and said reaction chamber do not circulate to substantial extent through the spaces between said baffle plates and said partition. 7

12. Apparatus for effecting chemical reactions which comprises a casing providing a reaction chamber and a manifolding chamber adjacent one end of said reaction chamber, a partition having openings therein extending across said casing to separate said reaction chamber from said manifolding chamber, double or nested conduit assemblies extending within said reaction chamber, each conduit assembly comprising an insert or inner conduit and a surrounding outer plates shielding substantially the entire area of said partition and fitting around said inserts so as not to obstruct the entry of fluids intosaid inserts, said plates being of material which will not absorb liquids and which is heat resistant, and means for holding said baflles in spaced relation to said tube sheet.

13. Apparatus for effecting chemicalreactions which comprises a casing providing a reaction chamber and a manifolding chamber adjacent one end of said reaction chamber, a partition having openings therein extending across said casing to separate said reaction chamber fromsaid manifolding chamber, double or nested conduit assemblies extending within said reaction chamber, each of said conduit assemblies comprising an insert open at both ends and communicating with said manifolding chamber through one of said openings in saidmartition, said inserts or inner conduits projecting beyond said partition; bafiie plates, of material which will not absorb liquids and is heat resistant, shielding substantially the entire area of said partition and fitting around said inserts so as not to obstruct the entry of fluids into said inserts, baflie plates extending in adjacent but spaced relation with those portions of the casing walls bounding said mani folding chamber which are nearest to said partition, ahd means for holding all of said bafiie plates fixedly in spaced'relation with the said partition and walls which they shield, the edges of said baiiies being arranged relatively to each other and to the walls of the manitolding chamber so as approximately to exclude fluids passing between said manifol ding chamber and said reaction chamber from circulating through the spaces between said baflie plates and the surfaces which they shield.

EUGENE J. HGUDRY. s

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