REFRACTORY LINING ANCHORED TO WALL OF VESSEL

Abstract: A refractory lining anchored to a wall (23) of a vessel comprises metal anchors (10) attached to the wall and which support the refractory lining relative to the wall. Each anchor (10) has a curved central web (11) and curved legs (12, 14) which together have a shape that approximates that of the letter C. The anchor also has straight arms (15, 16) extending outwardly from the central web which together have a shape approximating the letter W. The arms and legs improve the ability of the anchor to control the crack pattern that forms in the refractory after thermal cycling, thereby reducing catalyst ingress or coke formation in the cracks.

Description: FIELD OF THE INVENTION This invention relates to improvements in refractory linings for process vessels. More particularly this invention relates to an improved anchor for, and/or used with, thin refractory linings for process vessels and equipment such as cyclones and the like. BACKGROUND OF THE ART It is well known in the art to use refractory linings in process vessels, reactors, conduits, furnaces and the like as a means of thermal insulation. It is also known to use refractory liners in fluidized catalytic reactors and cyclones which are subjected not only to high temperature but also erosive material in order to provide protection against erosive as well as thermal insulation. Typically, refractory linings are anchored to vessel walls, such as cyclone bodies, by means of a hexagonal steel grating the thickness or depth of which is equal to the thickness or depth of the refractory lining to be deposited on the vessel wall. The disadvantages of such a refractory anchor are well known. They include installation difficulty, preferential erosion of the exposed metal and cost. Thus, a need exists for a refractory anchor which will overcome one or more of the disadvantages of anchors presently in use. Basically the present invention is directed toward an anchor used to retain thin refractory linings in process vessels such as cyclones and the like. In its simplest sense, the anchor of the present invention has a curved central web and curved legs which together have a shape that approximates that of the letter C. The anchor also has straight arms extending outwardly from the central web which together have a shape approximating the letter W. The arms and legs improve the ability of the anchor to control the crack pattern that forms in the refractory after thermal cycling, thereby reducing catalyst ingress or coke formation in the cracks. The present invention provides a composite structure comprising: a metal surface: a refractory lining for providing thermal protection to said surface; and a plurality of metal anchors welded to said surface in spaced apart relationship for providing crack control of said refractory lining during thermal cycling thereof, each of said anchors having a generally curved central web and curved legs extending from said central web, said central web and said legs defining substantially a semi-circle, straight arms extending upwardly and/or away from said curved central web, the total width of said anchor being substantially equal to the thickness of said refractory lining, said arms extending at a predetermined angle (theta) with respect to the diameter (d) of said semi-circular web and leg portion of said anchor, said anchor having at least one hole and tab in said central web. Preferably, the said predetermined angle (theta) is in the range of from about 25° to 50°, e.g., about 35°. The said anchor may have two holes and two tabs, and the said tabs may extend outwardly on opposite sides of said central web. The said web portion may be from 1.5 to 5 times the length of said arms and legs. Preferably the width of said legs is sufficient to permit the crack pattern resulting in the refractory lining on thermal cycling to propagate to the surface of the refractory. The tabs are preferably longer than they are wide and the tabs may be slightly curved. The invention also provides a vessel comprising a composite structure as described herein. These and other features of the invention will be better understood upon a review of the detailed description in light of the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 is a side view partly in perspective of a preferred form of the present invention. Figure 2 is a top view of an anchor of the present invention. Figure 3 is a view of several anchors of the present invention mounted against a vessel wall. Figure 4 is a frontal view of a plurality of anchors embedded in and supporting a refractory lining. DETAILED DESCRIPTION OF THE INVENTION Anchor 10, shown particularly in Figures 1 and 2, consists of a metal strip having a curved central web portion 11, downwardly curved legs 12 and 14, and upwardly extending straight arms 15 and 16. The anchor 10 of the present invention is particularly adapted for use with thin refractory linings, e.g., linings ranging in thickness from about 3/4 to 1 1/2 inch (1.9 to 3.8 cm) and most usually 1 inch (2.54 cm). Consequently, the width of the anchor 10 will generally be equivalent to the thickness of the refractory lining, namely, in the range from about 3/4 to 1 1/2 inch (1.905 to 3.810 cm). As can be seen from Figures 1 and 2, the curved central web 11 and legs 12 and 14 when viewed from the top substantially form a semi-circle. The anchor 10 is provided with at least 1 hole and preferably 2 holes 17. The holes are lanced from the central web 11 so as to provide extending tabs 18, one on each side of central web portion 11. The length of the tab or tabs 18 is not critical. In general, the total length of the tabs will be no more than about 2/3 the length of the central web portion 11. Thus, if two tabs 18 are lanced from the web, the combined length of these will be about 2/3 the length of web 11. Also, it should be noted that the tabs 18 are generally rectangular in shape, albeit slightly curved and extend in a plane perpendicular to the surface on which the anchor is to be mounted. As can be seen, particularly in Figure 2, the arms 15 and 16 of the anchor 10 extend upwardly and outwardly at a predetermined angle, theta, with respect to the diameter, d, of the semi-circle circumscribed by legs 12 and 14 and web 11. Normally the angle theta will be in the range of about 25° to about 50° and preferably is 35°. It is particularly preferred in the practice of the present invention that the length of the legs 12 and 14 be substantially equal to the length of the arms 15 and 16. In general, body portion 11 of anchor 10 will have the length from about 1.5 to 5 times the length of arms 15 and 16 and legs 12 and 14. The width or depth of the arms 15 and 16 and legs 12 and 14 can vary widely. In the practice of the present invention, however, it is preferred that the width of legs 12 and 14 be sufficient that the crack pattern that results in the refractory upon thermal cycling will propagate from the base of the refractory to its surface. Turning now to Figure 3, the anchor 10 is shown welded by welds 22 to metal surface 23 along the bottom edge 20 of anchor 10. As arranged, the legs 14 and 12 curve downwardly, whereas the arms 15 and 16 extend upwardly. The anchors may, of course, be arranged in any desired pattern and direction. As indicated, the anchors of the present invention are particularly suitable for use in refractory lined cyclones. Also, as was indicated, the anchors 10 are arranged on the wall of the vessel so that the legs 14 and 15 curve downwardly. Thus, the long dimension of each anchor is basically disposed transverse to the vertical axis of the cyclone barrel. Turning in alternating rows to Figure 4, the anchors 10 are shown spaced apart from each other in alternating rows and disposed in a refractory 42. It has been found that the anchor of the present invention results in propagation of cracks in the refractory lining after thermal cycling along the arms and legs thereby generating a tiled pattern with the various segments having a shape that is readily retained, particularly when tabs are employed that extend into the segments. 1 inch = 2.54 cms.

Claims: A composite structure comprising: a metal surface (23); a refractory lining for providing thermal protection to said surface: and a plurality of metal anchors (10) welded to said surface in spaced apart relationship for providing crack control of said refractory lining during thermal cycling thereof, each of said anchors having a generally curved central web (11) and curved legs (12, 14) extending from said central web, said central web and said legs defining substantially a semi-circle, straight arms (15, 16) extending upwardly and/or away from said curved central web, the total width of said anchor being substantially equal to the thickness of said refractory lining, said arms extending at a predetermined angle (theta) with respect to the diameter (d) of said semi--circular web and leg portion of said anchor, said anchor having at least one hole (17) and tab (18) in said central web. The composite of claim 1 wherein said predetermined angle (theta) is in the range of from about 25° to 50°. The composite of claim 2 wherein said predetermined angle (theta) is 35°. The composite of claim 3 wherein said anchor has two holes (17) and two tabs (18). The composite of claim 4 wherein said tabs (18) extend outwardly on opposite sides of said central web (11). The composite of any one of claims 1 to 5 herein said web portion (11) is from 1.5 to 5 times the length of said arms and legs. The composite of any one of claims 1 to 6 herein the width of said legs is sufficient to permit the crack pattern resulting in the refractory lining on thermal cycling to propagate to the surface of the refractory. The composite of any one of claims 1 to 7 wherein said tabs (18) are longer than they are wide and wherein said tabs are slightly curved. A vessel comprising a composite structure according to any one of claims 1 to 8.

Inventors: CHEN, TE-HUNG, CICCHINO, DOMINIC, SHADBOLT, PETER JAMES
Applicants: EXXON RESEARCH AND ENGINEERING COMPANY
Application year: 1987
Main classification: F27D1
IPC codes: F27D1, F23M5, B04C5, B01J19