US 2243240 A
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Description (OCR text may contain errors)
H May 27, 1941. F. K. ZERBE 2,243,240
PRESSURE VESSEL FOR HYDROGENATING HYDROCARBONS Filed March 18, 1938 2 Sheets-Sheet l Iii l l l i I I i 1 I i FrederickKZerbe INVENTOR.
y 27, 1941- F. K. ZERBE 2,243,240
PRESSURE VESSEL FOR HYDROGENATING HYDROCARBONS 7 Filed March 18, 1938 v 2 sheets sheef 2 FI /z5 Frede rick K. Zerbe INVENTOR ATTORNEY.
Patented ay 2?, 1941 v iros'rAs H mm PRESSURE VESSEL FOB ROGENATING If -7 r= N3 Frederick K. Zerbe, Granville, Wia, assignor to A. 0. Smith Corporation, corporation of New York Milwaukee, Wis., 'a
Application March 18, 1938, Seriai N 0. 196,768
hydrogenating apparatus from alloys of steelsuch as aluminum, chromium, molybdenum, tungsten, vanadium and manganese steels having a low carbon content. Because of the character of the compounds used and the temperatureconditions, the alloy composition must be capable of resisting chemical reaction as well as the eflect of hydrogen absorption.
These vessels have been made in the form of long narrow cylinders with walls of extreme thickness to withstand the very high internal pressures employed. Materials, such as those mentioned, which are less-injuriously afiected by hydrogen embrittlement are much more expensive than plain carbon steel and increase the already relatively high cost of this process of obtaining lighter hydrocarbons. The rolling of heavy plate stock or the forging of single piece vessels presents additional problems and added expense in the-fabrication oi such vessels.
It is an object of the. present invention to produce an improved vessel of multi-layer construc'tion, which has increased resistance to pressure and heat and which may utilize plain steel material without any danger of embrittlement.
A further object of the present invention is to provide a vessel of increased diameter without involving expensive rolling or forming operations.
A still further object is to provide a vessel which is less apt to explode than vessels heretofore used in this process.
Another object is to protect an brittlement and deterioration.
The invention is illustrated in the accompany-- ing drawings in which:
Figure 1 is a longitudinal central section of a vessel embodying the invention; I
Fig. 2 is an enlarged circumferential section ordinary steel vessel used in hydrogenation processes from emthrough a portion of the wall of the vessel, the central portion being broken away to reduce the length of the view;
Fig. 4 is a side elevational view of a portion ofthe body of the vessel partially fabricated; and
Fig. 5 is a view similar to Fig. 4 showing a modified construction.
Vessels of multi-layer construction have been made in accordance with the teachings of U. 8.
.Pat. No. 1,925,118 issued -on September 5th, 1933,
to Richard Stresau and assigned to the A. 0. Smith Corporation of Milwaukee, Wisconsin, the assignee of the present application. The present invention relates to certain improvements in the type of vessel disclosed in said patent which make it adaptable to the process of hydrogenation.
As illustrated in Fig. 1, the vessel comprises a number of'ring sections ii and is closed at one end by a permanently attached head !2. The
other end of the vessel is equipped with a closure,
which may be. removed for cleaning out the interior oi the shell. The closure is conventional and no claim is made to its construction. Instead of employing the heads illustrated, both heads may be ellipsoidal or both may be removable closures and it is also possible to construct the heads of multi-layers instead of single piece forgings. The
more impervious to hydrogen and of part of the vessel taken along the line 2--2,
closure shown consists of a flanged ring 13, the
inner and outer diameters of its body portion corresponding to those of the vessel shell, and a head H with a flange corresponding to the flange on the ring it. The flanges are brought together by a pair of clamps ii of annular shape, the inner surfaces of which are grooved to correspond with and enclose the aforementioned flanges.
The clamps may be tightened by bolts or any suitable means. A gasket I6 is provided to seal the joint between the head I4 and the ring l3.
Any number of ring sections ll may be em- I ployed depending upon the length of vessel desired. The circumferential joints between the rings and the end members are fused together icy arc welding in a manner to be more fully described hereafter.
Each ring section is composed of a number of layers of cylindrically' shaped plate members, preformed and welded along the longitudinal seams created by fthe meeting edges of the plates. The innermost layer i1 is formed from a plate of metal or alloy which is preferably less injuriously infected by it than plain carbon steel. A
suitable material.,. is a chrome-vanadium alloy steel having about 1.5% chrome and .20 to 25% vanadium. The carbon content of the alloy may approximate 20%. Where replacement of the inner layers is possible, in certain instances ordinary steel may be employed.
The welding of the longitudinal seams in the formed and drawn tightly over the inner ring to bring the ends into abutting relation for welding. Seams should be ground flush to permit close engagement of layers. After the seams are welded, strips I! are tack welded longitudinally of the shell outside of layer It. These strips are preferably about 1 inches wide by! about M; inch thick and extend longitudinally of the vessel. Gaps 20 are provided between parallel strips in a longitudinal direction about of an inch wide. Several strips may conveniently be arranged lengthwise of each ring section. A number of circumferential spaces 2i of about y inch width are provided in the central portion of each ring section and adjacent the welds. The spacing is best illustrated in Figs. 2, 3 and 4.
Qther arrangements of the strips may be made, such as wrapping circumferential strips l9 around the inner layers either as rings, as shown in Fig. 5, or in the form of a spiral. Various other embodiments of the invention may be made, the principal object being to provide a chamber between layers covering as large an area of the shell as possible and yet supportin subsequent layers.
In the embodiment illustrated the strips l9 are'formed of either plain carbon steel or of alloy and are welded to layer It by fillet welds. Where strips of alloy metal similar to the inner layer are employed, it is possible to eliminate the intermediate layer l8 and to weld the strips directly to the layer 11 without causing undesirable dilution of the latter. It is also possible to eliminate the layer It when employing plain carbon steel strips by welding the strips to the inside of a subsequent layer. 1
A layer 22 is next formed and drawn over the shell section previously fabricated. This layer is formed from/a plate of similar'alloy as the layers l1 and I8. Welding conditions are preferably maintained similar to those described in connection with the first layer and each weld is preferably stressrelieved prior to the application of additional layers. Each plate is drawn tightly over the preformed structure and'held clamped during the welding process.
Additional layers 23 are built up around the shell until a vessel of the desired thickness is obtained. Outer layers 23 need not be impervious to hydrogen, but may be formed from plain carbon steel plates. In fabricating the outer layers the practices set forth in the Stresau patent previously mentioned may be followed, with seams either superimposed or staggered. As '11- lustrated the circumferential seams are superimposed and a deep groove is provided for theweld deposit 24. This groove may be formed.
by using-layers of slightly decreasing width or by chipping out a tapering groove after the layers are wrapped and the longitudinal seams Welded.
able number of holes are drilled in each ring section to.insure sufllcient communication with the outside of the vessel.
In addition to these holes, ordinary vents, as disclosedin the Stresau patent, may be provided Such vents prevent the exertion of extreme pressure on the outer layers should a break occur in the inner shell and also permit the escape of air when the layers are expanded by in-v ential seams or girth joints in which thermocouples may be inserted to measure the temperature at the inside of the vessel. Such wells extend to the first plain steel layer. but are in direct thermal communication with the innermost layer because they are drilled into the weld which extends to those layers.
By use of the structure disclosed, any hydrogen or other gas which may be absorbed in the steel and passes through the innermost layers will be conducted to the communicating passages 20 and 2| formed by the spaces between the strips l8 separating these layers from the outer layers, From here the gas is conducted to the outside of the vessel by means of the holes 25. There is no danger of embrittlement in the outer layers of weld deposits along girth join-ts because the passages adjacent the weld provide an area of low pressure for, gas removal.
When the vessel just described is subjected to opera-ting conditions, the gases absorbed in the inner layers will gradually find their way to the passages 20 and 2t formed between the strips is. These passages are at low pressure because of the external communications and act to protect the whole shell surface. The gases followtlally cylindrical surface to support the outer layers of the vessel. ,By this design, it is possible to press the outer layers tightly around the inner shell and obtain the advantages of layer construction in resisting high internal pressures.
The rate of hydrogen penetration into the steel adjacent the interior of the vessel is dependent upon the temperature and pressure. Under the high temperature and pressure conditions of hydrogenation processes'gas penetration is rapid and embrittlement quickly deteriorates the metal. In describing the alloy metals used in the inner layers, the term resistant to gas absorption is used in the specification and claims to mean an alloy metal which may have high resistance to gas penetration, greater resistance to embrittling effects resulting from the.
absorption of gas in thematerial, or both. Some penetration cannot be avoided, but this gas, although at high temperatures, does not injuriously affect the outer shell stock because of the pressure relief afforded by the gas collection chamber communicating with the outside of the vessel. Meanwhile longer life to the inner layer or layersis obtained through the selection of an alloy metal having resistance to gas absorption as described herein.
In selecting material for the outer layers, it is contemplated that an alloysteel such as molybdenum steel may be used rather than a plain, low-carbon steel to obtain greater strength. This invention is not limited to any particular choice of steels, but itsadvantages are equally applicable to' all steels through the protection afforded I sistant to gas absorption, and theouter section of said shell being formed of layers of material protected by the inner section from injury by gas absorption, said outer section being additionally protected from gas absorption by a series of interconnected passages between two adjacent layers of said vessel and communicating with the outside of the vessel for withdrawing gas passing through the inner layer, at least one of said two adjacent layers being a layer of said inner section.
2. A pressure vessel for use in chemical processes in which nascent hydrogen is present in the vessel under conditions of high temperature and pressure, and having a steel shell-comprising a plurality of layers of sheet metal concentrically arranged in close engagement with one the outer still shell by the means here disclosed.
,Instead of using chrome vanadium steel for the inner layers, a 4-6% chrome alloy is suggestployed in the layer constructed vessel.
The heads are made of substantially similar material as the inner layers and are preferably forged and machined to accurate dimensions. Suitable openings 21 are provided in the heads for bringing the oils and gases into the -vessel and for conducting them therefrom. The heads may be constructed of layers similar to those of the shell Various embodiments of the invention may be made within the scope of the following claims.
1. A pressure vessel comprising a shell formed from a plurality of layers of metal welded together, the inner section of said shell being formed of a plurality of layers of material reanother, said shell being separated-into an outer section for withstanding the working stress and a relatively thin inner section by a series of spacing elements serving to transmit the working stresses from the inner section to the outer section, said elements being so spaced as to pro-' vide a series of inter-communicating chambers between said sections for the collection of hydro- I gen passing through the steel, and means communicating with said chambers through the outer section to relieve the gas pressure created therein.
3. A pressure vessel comprising a shell formed from a plurality of. layers of metal welded together, the inner section of said shell being formed of a plurality of layersof material resistant to gas absorption, and the outer section of said shell being formed of layers of material protected by the inner section from injury by gas absorption, said outer section being addi- ,tionally protected from gas absorption by a series of interconnected passages formed between two adjacent layers by spacing elements of material resistant to gas absorption, said elements being welded to the adjacent inner layer and serving to transmit working stress to the outer layers of said vessel, said passages having communication with the outside of the vessel for withdrawing gas passing through the inner section, and the inner layer of said two adjacent layers being a layer of said inner section.