US2788266A

US2788266A - Catalytic reactor furnace

Info

Publication number: US2788266A
Application number: US313381A
Authority: US
Inventors: Stirnemann Ernst
Original assignee: Individual
Current assignee: Individual
Priority date: 1951-10-13
Filing date: 1952-10-07
Publication date: 1957-04-09
Anticipated expiration: 1974-04-09

Description

April 1957 E. STIRNEMANN CATALYTIC REACTOR FURNACE Filed Oct 7, 1952 INVENTOR.

FRIVJT J'T/R/VfH/Ifi/V United States Patent CATALYTIC REACTOR FURNACE Ernst Stirnemann, Basel, Switzerland Application October 7, 1952, Serial No. 313,381

Claims priority, application Switzerland October 13, 1951 3 Claims. (Cl. 23-488) This invention relates to devices for carrying out chem- 1cal reactions at high temperatures and more particularly reactions in the gaseous phase, such as the production of hydrocyanic acid from HsN and hydrocarbons at temperatures in the range of about 600 to 1300 C.

In carrying out such reactions, in general heat must be supplied to and/or drawn off from the walls of the reaction vessels. The use of elongated reaction spaces, such as elongated flat chambers and particularly the use of tubular reaction vessels oifers certain advantages in said reactions. On the other hand, the use of such elongated reaction vessels involves also certain difficulties, which are primarily caused by the effect of the high temperatures. At high temperatures of the betorementioned range, elongated tubes and similar elongated vessels are subjected to certain undesired influences, which occur, as a result of temperature variations, particularly during the starting and/or end period of the reaction, as well as during interruptions caused by disturbances. Such influences may cause serious trouble due to thermal expansion of the tubes, or the like, or to their contraction upon cooling and may result in plastic deformations or even fractures. In view of these eflects, it is rather .difficult to fasten or mount tubes and other elongated reaction vessels in an oven in such manner as to avoid adverse efiects and resist strains occurring during continued operation of the device.

It has now been found that the above described difiiculties can be overcome by arranging the elongated reaction vessels in substantially vertical direction in the heated space of the oven or furnace, and keeping only the lower ends of the reaction vessels in fixed position, while subjecting each elongated vessel at its upper end to pull in the direction of its axis. This pull balances at least part of the weight of the reaction tube or the like, so that the tube does not rest with its full weight on its stationary support. The pulling force can correspond to the full weight of the tube, but it may be also somewhat smaller or even somewhat higher. In any case, the amount of pull should be selected in such manner that the tube is permanently in well stretched condition and does not tend to be bent or distorted at high operating temperatures.

The upward pull applied to the tubes or the like, can be brought about by counter-weights suspended on a rope or cable, which is connected to the free upper end of the tube or the like and is guided over rolls. Furthermore, suitable springs can be also used for applying pull to the upper end of the elongated reaction vessels.

According to an embodiment of the invention, the elongated reaction vessels, preferably tubes, are not rigidly fastened at their lower ends, but mounted in such manner that they are movable Within a small range in axial direction. This range is limited preferably by one stop, or, if desired, by two stops. If the amount of upward pull is somewhat higher than that necessary for carrying the reaction tube or the like, it is sufficient to provide the lower tube end, which projects from the oven, with 2,788,266 Patented Apr. 9, 1957 a pipe clamp or the like, having projecting parts, which, upon displacement by pull of the tube in upward direction, are arrested by a stationary stop, so that the tube will then come to a rest position. If the amount of pull is slightly in excess of that necessary for carrying the weight of the reaction tube, an elastic connecting element for gas supply or gas discharge, e. g. a flexible metal pipe or a spiral tube, may be sufficient in order to prevent undesired displacement of the tube in axial direction.

The elongated reaction vessels may consist of ceramic or metallic material. As an example of ceramic materials Sillimanit, i. e. an aluminum silicate rich in aluminum oxide, sintered corundum, and porcelain clay are mentioned. As metallic materials, highly heat-resistant steels or other highly fireproof alloys, e. g. iron-nickelchromium alloys rich in chromium, or iron-nickel-aluminum alloys can be used. Metallic materials have the advantage that they are not brittle.

The devices according to the present invention can be used also in processes requiring extremely high temperatures, at which the walls of the reaction vessels become to a slight extent plastic. In such cases, deformations or other damage, are prevented by the effect of upward pull, which balances the own weight of the reaction vessel. This advantage has a particularly favorable influence in the use of metallic tubes or tubes consisting of relatively inexpensive ceramic materials, because according to the invention reactions can be carried out in such tubes or the like even at very high temperatures which, under conventional conditions, would adversely afiect the walls of the reaction vessels.

Heat can be supplied to the reaction tubes or the like, in conventional manner by external heating.

The appended drawing Figure 1 diagrammatically illustrates, by way of example and without limitation, an embodiment of the invention, in which the elongated reaction vessel is movable within a small range in axial direction, while in the similar view of Figure 2 the lower end of the reaction vessel is in fixed position.

Referring to the drawings in detail, 1 denotes a stationary oven provided with vertically arranged react-ion tubes. 3 is an elongated reaction tube provided with heating elements 2, consisting, for example, of nickelchromium or Fe-CrSiAl resistance wire or of SiC. 11 denotes isolation applied to reaction tube 3. The upper part of tube 3, which projects from the oven, is provided with a pipe clamp 4 to which a cable or rope 5 is fastened. This cable or rope is guided over

rolls

6, 6 and carries weight 7 suspended thereon. The desired upward pull in axial direction of tube 3 is brought about by the efiect of weight 7. 21 and 12 are elastic or movable pipe connections for the supply and discharge respectively of gaseous starting materials and reaction products.

In the modification shown in the drawing, the free lower part of tube 3, is likewise provided with a pipe clamp 8. Above the latter is a stationary stop 9 and below pipe clamp 8 is a stationary stop 10.

The following variations may be used in the device shown in the drawing:

(a) Weight 7 exceeds the weight of tube 3. In this case, pipe clamp 8 abuts against stationary stop 9 of the oven. Therefore, tube 3 can freely expand under the action of weight 7 upward and remains permanently under a certain pull.

(b) Weight 7 is smallerrthan the weight of tube 3. In this case tube 3 rests with a small fraction of its weight on stationary stop it) while the greater part of the weight of tube 3 is compensated by weight 7. In this case too, reaction tube 3 can expand in upward direction under slight pull.

() Weight 7 is equal to the weight of reaction tube 3. In'this case upper stop 9 as Well as lower stop 10 can be operative and compensation of the weight of tube 3 by the pull of weight '7 takes place between variations a and b. Theinvention results in considerable advantages. it has been found that arrangement of the elongated reaction vessels, particularly tubes, in the oven according to the invention, offers optimum conditions for maintenance and duration of the tubes and the important advantage of easy exchangability of the elor "it-ed r n vessel's. The use of guide elements which may cause cracking of tubes consisting of ceramic material in View of temperature diiferences between the heated tube and colder guide elements, is not necessary according to the present invention. Furthermore, in the use of metallic tubes which are designed as heatable elements, tions with electric conduits can be effected in a pa larly simple manner.

In order that those skilled in the art may better understand how the present invention may be practiced, the use of the device according to the invention for the reduction of hydrocyanic acid is given by way of illustration and not by way of limitation.

A mixture of NH3 and CH4 in the proportion of 1:1 is supplied through elastic or movable tubes 11 to the lower end of reaction tube 3. This reaction tube consists of Sillimanit the inner surface of which is lined with a catalytic foil of platinum-ruthenium containing about 20% ruthenium. The tube is heated to about 1100 C. and is maintained at this temperature. The reaction product containing the hydrocyanic acid formed is discharged from the upper end of tube 3 through movable or elastic pipe connection 12. About 96% of the NH3 introduced into the process is Converted into hydrocyanic acid.

It will be understood by those skilled in the art that the invention is not limited to the structural and other details described above and described in the drawing 4 300 cm. The devices embodying the invention can be used in the range of 900-1300 C.,aswell as at lower or higher temperatures, and for producing hydrocyanic acid or other reaction products. These and other modifications can be made Without departing from the scope of the invention as defined in the appended claims.

What is claimed is:

1. A device for carrying out chemical reactions at high reaction temperatures above 600 C., comprising in combination an oven, at least one elongated reaction vessel arranged in said oven and being bodily movable in its entire length in both axial directions, the ends of said vessel projecting through the top and bottom of the oven, respectively; said reaction vessel extending in substantially vertical direction; first means fixediy connected, at a point exterior of the top of the oven, with the upper end of each reaction vessel and having counter-balancing means, for suspending the upper end-s of the reaction vessels and subjecting, them. to positivepulling action in upward direction, and second means fixedly connected to the lower end of each reaction vessel, at a point exterior of the bottom of the oven; said second means being movable in vertical direct-ion within a predetermined range defined by two structural stationary stop members mounted below the oven, one of the stop members being located above said second means and the other stop memher being located below said second means, in order to limit vertical displacement of said second means and of the lower end of the reaction-vessel, and means for heating the react-ion vessels to reaction temperature.

2. A device as claimed in claim 1 in which the reaction vessels are heated electrically.

3. A device as claimed in claim 1 in which the reaction vessels are tubular.

References Cited in the file of this patent UNITED STATES PATENTS 1,428,323 Calvin Sept. 5, 1922 1,998,401 Shepard Apr. 16, 1935 2,173,984 Shapleigh Sept. 26, 1939 2,546,013 Peck et al Mar. 20, 1951 2,645,566 Stookey July 14, 1953 2,654,657 Reed Oct. 6, 1953 FOREIGN PATENTS 531,946 Germany Apr. 25, 1928 330,872 Great Britain June 19, 1930

Claims

1. A DEVICE FOR CARRYING OUT CHEMICAL REACTIONS AT HIGH REACTION TEMPERATURES ABOVE 600*C., COMPRISING IN COMBINATION AN OVEN, AT LEAST ONE ELONGATED REACTION VESSEL ARRANGED IN SAID OVEN AND BEING BODILY MOVABLE IN ITS ENTIRE LENGTH IN BOTH AXIAL DIRECTIONS, THE END OF SAID VESSEL PROJECTING THROUGH THE TOP AND BOTTOM OF THE OVEN, RESPECTIVELY; SAID REACTION VESSEL EXTENDING IN SUBSTANTIALLY VERTICAL DIRECTION; FIRST MEAN FIXEDLY CONNECTED, AT A POINT EXTERIOR OF THE TOP OF THE OVEN, WITH THE UPPER END OF EACH REACTION VESSEL AND HAVING COUNTER-BALANCING MEANS, FOR SUSPENDING THE UPPER ENDS OF THE REACTION VESSELS AND SUBJECTING THEM TO POSITIVE PULLING ACTION IN UPWARD DIRECTION, AND SECOND MEANS FIXEDLY CONNECTED TO THE LOWER END OF EACH REACTION VESSEL, AT A POINT EXTERIOR OT THE BOTTOM OF THE OVEN; SAID SECOND MEANS BEING MOVEABLE IN VERTICAL DIRECTION WITHIN A PREDETERMINED RANGE DEFINED BY TWO STRUCTURAL STATIONARY STOP MEMBERS MOUNTED BELOW THE OVEN, ONE OF THE STOP MEMBERS BEING LOCATED ABOVE SAID SECOND MEANS AND THE OTHER STOP MEMBER BEING LOCATED BELOW SAID SECOND MEANS, IN ORDER TO LIMIT VERTICAL DISPLACEMENT OF SAID SECOND MEANS AND OF LOWER END OF THE REACTION VESSEL, AND MEANS FOR HEATING THE REACTION VESSEL TO REACTION TEMPERATURE.