US 3043942 A
Description (OCR text may contain errors)
July l0, 1962 T. H. wlcKwlRE nl, ETAL 3,043,942
ELECTRICAL HEATING APPARATUS 2 Sheets-Sheet 1 Filed April 29, 1959 J a CZ INVENTORS Trbvoxrh'. w/acw/af July 10, 1962 T. H. wlcKwlRE m, ETAL 3,043,942
ELECTRICAL HEATING APPARATUS Filed April 29, 1959 2 Sheets-Sheet 2 IIIIIAif/f United States Patent vO 3,043,942 ELECTRICAL HEATING APPARATUS Theodore Hfwickwre III, Haverford, and George R. Connor, Collegeville, Pa., assignors to Trent, Inc., Philadelphia, Pa., a corporation of Delaware Filed Apr. 29, 1959, Ser. No. 809,726 1 Claim. (Cl. 219-19) This invention relates to electrical heating apparatus for high temperature furnaces and the like and in particular relates to refractory blocks and arrangements of such blocks in units for the mounting of electrical heating elements.
One object of the invention is to provide, for an electn'cal heating unit, a refractory block having an especially configured base by means of which the block can be easily and quickly inserted in or removed from a supporting means. v
Another object of the invention is to provide, for an electrical heating unit, a refractory block having a stemlike base by means of which the block can be quickly and easily supported on or removed from a furnace wall.
Another object of the invention is to provide, for an electrical heating unit, a refractory block having an especially configured base by means of which the block is readily mounted in a channel-like support configured to Vsurround the base and hold the same in position.
Another object of the invention is to provide, for an electrical heating unit, a refractory block formed with a base for mounting the block on a support and further formed with a mounting channel for supporting a heating element, the channel being spaced from the base Vto maintain the heating element away from the support. i Another object of the invention is to provide, for an electrical heating unit, a refractory block formed with a base for mounting the block on a support and further formed with a plurality of channels for supporting heating elements, the block being especially adapted for use in an arrangement having multiple spaced layers of heating elements.
Another object of the invention is to provide an electrical heating unit having -a refractory block for supporting a heating element, the block having a base configured to be disposed Within an enclosed channel member, the base and channel being dimensioned to allow the buildup of scale on the channel without exerting a force to crack the block.
Another object of the invention is to provide an electricalheating unit having blocks assembled in the unit without the use of fastening means such as screws, pins, dowels and the like, the blocks being for supporting electrical heating elements. Y
Another object of the invention is to provide an electrical heating unit including refractory means for mounting folded and formed heating elements in a vertical or ,Y
horizontal position. p
Another object of the invention is to provide an electrical heating unit having a plurality of refractory blocks and means for supporting the same so that any block, if damaged, can be quickly and readily replaced.
The manner in which the invention is constructed will be apparent from the following description and drawings wherein: A
FIGURE 1 is a front elevation-al view partially in section illustrating a typical heating unit constructed in accordance With the invention; Y FIGURE 2v is `a fragmentary isometric' View Ashowing certaino'f the refractory blocks used in the arrangement of FIGURE 1;I l I FIGURE 3 'is a cross section taken on the line 3-3 of FIGURE 1 and showing the cross section of a refrac- Mice tory block and the manner in which the block is mounted in a support;
FIGURE 4 is a cross sectional view of a multiple channel refractory block;
FIGURE 5 is a front elevational view partially in section illustrating another typical heating unit constructed in accordance with the invention;
FIGURE 6 is a cross section taken on the line 6-'6 of FIGURE 5 and showing the cross section of a refractory spacer and the manner in which the spacer is mounted in a support; f
FIGURE 7 is an isometric view of the spacer of FIG- URE 6;
FIGURE 8 is a front elevational View illustrating a unit of the invention as applied directly to Ia furnace wall of fire brick;
FIGURE 9 is a vertical section taken on the line 9-9 of FIGURE 8; and
FIGURE 10 is an isometric view of a typical refractory block used in the unit of FIGURE 8.
In FIGURE 1 we have shown a typical heating unit including a pair of spaced supports 1 and 2 respectively mounting a plurality of refractory blocks 3 between which is supported a heating element 4, the supports 1 and 2 being coupled together by means of the brackets 5 and 6.
The Iheating element 4 is preferably of the type shown in the Trent Patent No. 1,928,142 or Fisher Patent No. 2,856,496 both assigned to the assignee of this invention. By means of the brackets 5 and 6 the unit may -be attached to the top or bottom of a furnace. Also, the unit may be attached to the sides of the furnace where it is desirable that the legs of the heating element run ver- Itically. The free ends 4a and 4b of the heating element are adapted to be attached to power lines (not shown). It is pointed out that `more than one heating element may be used in a unit for the purpose of temperature control `and the like. For example, the element 4 may, in certain instances, comprise two adjacent elements both connected to control means so that the same can be independently energized.
In the unit of FIGURE-l all of the refractory blocks are preferably of the same size and shape as illustrated in FIGURES 2 and 3. Each block has an axially elongated body 11 on one side of which are a pair of spaced projections 12 and 13 and on the opposite side of which are spaced projections 14 and 15. The projections 12 and 13 form a mounting channel 16 and the projections 14 and 15 form a mounting channel 20. Asl illustrated, the mounting channels of the various adjacent blocks are generally coaxial so that channels of the blocks on the support 1 form a mounting channel C and the `channels of the blocks on the support 2 form a mounting channel C-1. The channels C and C-1 face each other and the heating element 4 is supported therebetween the ends 7 of the element being disposed in the channels as illustrated.
Each refractory block is also formed with a base 21 which includes two portions 22 and 23 projecting outwardly of the block and spaced from the channels 16 and 20. The base constitutes means for mounting the block in its support. With reference to FIGURE 3 it will be seen that the support 1 is C-shaped in cross section so as to form a retaining channel 24 which fits over the base 21. The mouth of the channel is of smaller width than the width of the base so that the block cannot be pulled outwardly through the mouth. Each block and the support 1 are configured so that there is sufficient clearance -for each block to be shiftable axially in the supporting channel. Furthermore, this clearance is of an amount sufficient to allow scale build-up on the support without exerting a force on Vthe refractory block sufficient to crack the same.
The refractory blocks are retained in the supports by means of the tabs 30, 31, 32 and 33 which are bent into the respective retaining channel and thereby prevent the blocks from slipping outwardly.
In assembling the unit of FIGURE 1 the support members 1 and 2 are'attached to the brackets 5 and 6. With the tabs 30 and 32 bent outwardly of the retaining channels and the tabs 31 and "33 bent into the retaining channels, the various refractory blocks are then slid into the respective retaining channels from the left side to the right and then the tabs 30 and 32 are bent inwardly. The heating element is then slid into the mounting channels C and C-1 either from the Vleft or right-hand side. Preferably the tabs and the blocks are dimensioned so that with the tabs bent inwardly to hold the blocks in place, there is a small clearance space between each block so that the same are somewhat loose in position.
There are several advantages of the above-described arrangement. For example, it will be observed that all of the refractory blocks are held in the unit without the use of screws, bolts or other pressure exerting devices. This is highly advantageous because metal screws, bolts, pins and the like tend to exert pressure on a block due either to thermal expansion or to the build-up of scale which promotes cracking of blocks, especially under high temperature conditions, Another advantage of the invention is that a refractory block can be quickly replaced if the same is damaged. `For example, suppose that the refractory block marked X in the channel 1 became damaged. To replace this block it is merely necessary to bend out the tab 31 and push the block X and the two blocks to the right of the same out of the channel and then reinsert two blocks with a replacement block and then bend down the tab '31. Another particular advantage of the unit is that the refractory blocks are adapted to mount the heating element so that there is substantial clearance between the element and the part of the furnace to which the brackets and 6 are attached. This will be readily apparent from an inspection of FIGURE 3, This spacing of the heating element is highly desirable from the standpoint of avoiding hot spots and promoting the radiation efliciency of the element.
Another advantage of the invention is that it is readily adaptable for the construction of units having a plurality of adjacent or side-by-side heating elements. For example, it will be apparent that the brackets 5 and 6 may be made of greater length than shown and have an additional support (constructed along the lines of the supports 1 and 2) secured thereto adjacent, say, the support 1 with refractory blocks (having the same size and shape of the blocks 3) disposed therein. In this construction the mounting channels of these blocks face the channel G-Z formed by the channels of the blocks 3. A heating element such as element 4 is inserted between these channels.
Still another advantage of the invention is that it is readily adaptable where a heating unit is to comprise a stack or multiple layers of heating elements. For example, in FIGURE 4 I have shown a refractory block 34 having a body* 35, a base 36 and a plurality of projections 40 which form mounting channels 41, 42, 43, 44, 45 and 46. It will be noted that the base 36 of the block 34 is configured along the lines of the block of FIGURE 3 so that the same is readily adaptable for use with a support 47 having the same shape as the supports 1 and 2.
It will be apparent that if the blocks 3 of FIGURE 1 are replaced by blocks such as shown in FIGURE 4, heating elements such as elements 4 may be inserted in the appropriate channels to make a heating unit having three stacked elements.
The heating unit of FIGURE 5 is useful for furnace wall mounting, particularly where it is desirable that the legs of the heating element run in a horizontal direction. The unit of FIGURE 5 is similar to the unit of FIGURE l except that certain of the refractory blocks are of different axial length and spacers are used between the blocks to provide for vertical support of the heating element. This unit comprises the supports 5t) and 51 which are configured the same vas the supports 1 and 2 of FIGURE l, these supports being mounted on the brackets 52 and 53 which are adapted to be secured to a furnace wall. The support 5G has a tab 54 bent into the channel and this tab supports a refractory block 55. The support 51 has a tab 56 which supports the refractory block 6i). On top of the block 55 is a spacer 61 and on top of the block 60 is a spacer 62. The shape of these spacers will be explained shortly. On the spacer 61 there is a block 63 which carries a spacer 64 on which there is another block 65 mounting a spacer 66 on which there is a block 67, and on the block 67 there is la final spacer 7i). On the right-hand side the spacer l62 carries a block 71 on Which there is a spacer 72 mounting a block 73 carrying the spacer 74 and finally on the spacer 74 another block 75.
The configuration of the spacer mentioned above is shown in FIGURES 6 and 7. The spacer comprises a body 76 having a base 76 which is configured the same as the base 20 of FIGURE 3. The top part of the body of the spacer is similar to the block of FIGURE 3, except that there are no projections to form channels. In other words, the spaces which are occupied by the mounting channels 16 and 20 of the block of FIGURE 3 is occupied by ceramic material in the spacer. This causes the spacer then to project into the channel formed by the adjacent block. For example, in FIGURE 5 it will be seen that the portion 74 of the spacer 74 projects between the channels 73 and 75 of the blocks 73 and 75. The channels 73 and 75' in effect then become pockets.
The various blocks are made of an axial length so that the end 77 of the heating element 78 projects into the various pockets and rests on the various spacers as indicated.
In assembling the unit of FIGURE 5 the two supports 50 and 51 are assembled with their respective blocks and ispacers in position. The heating element is then placed between the assemblies so that the ends of the element fit into the pockets as shown. Then the supporting means 50 and 51 are xedly secured to the brackets 52 and 53. The ends 78a and 78b of the heating element are connected to 4a power source not shown.
In FIGURE 8 we have shown a unit of the invention which is directly applied to a furnace wall, with the use of supports or brackets such as described in connection with FIGURES 1 and 5. In the unit of FIGURE 8 the refractory blocks have a base structure which permits the same to be attached directly to the supporting furnac wall. i' ffl The configuration of a refractory block for the unit of FIGURE 8 is shown in FIGURE 10 and comprises a body 80 having a pair of projecting portions 81 and 82 on one side which form a channel 84 together with another pair of projecting portions 85 and 86 which form a channel 90. The base comprises a stem-like portion 91 which projects outwardly `ot the body substantially at right angles to the channels 84 and 85.
In making up the unit of FIGURE 7, rst a long horizontally extending slot 92 (see FIGURE 9) is cut in the .furnace wall and then a plurality of blocks 93 (having the configuration of the block of FIGURE l0) are mounted on the wall by inserting the base 91 into the slot and securing the same in place by re clay 94 or the like. Then a similar slot 1100 is cut in the wall and the blocks 95 (having the same configuration as the blocks of FIG- URE 10) are cemented in place. When the blocks 93 and 95 are firm in the wall the heating element 101 is 5 mounted in the blocks by sliding the `same into the channels 102 and 103.
The arrangement of FIGURES 8 and 9 -has particular advantage over the usual heating element arrangement supported directly from a furnace wall. In the usual arrangement it is necessary that the refractory supports be cemented in when the furnace wall is built and, therefore, it is very diiicult to replace the same because several of the wall bricks have to be removed. Furthermore, the usual refractory support has no means for maintaining the heating element away from the Wall brick and this is highly disadvantageous in that it is conducive to the forming of hot spots and consequent reduction in the life of the heating element and also reduces radiation eiciency.
With the present ,arrangement a damaged block is quickly replaced by simply knocking off the body portion and then drilling and chiseling `out the base and then cementing a new block in the wall. Also, the mounting channels in the blocks space the heating element substantially away from the furnace wall 'as will be clearly seen from 1an inspection of FIGURE 9.
In an electrical heating unit: refractory means forming a Wall of the heating unit, the wall having a pair of spaced slots extending generally parallel to one another; two groups of refractory blocks, each block having a stemlike portion, the stems of one group yof blocks being disposed in one of said slots and the stems of the other group of blocks being disposed in the other of said slots and each of said blocks having a pair of spaced projections, the block and projection forming a channel and the channels in the two groups of blocks respectively cooperating with one another to form a pair of continuous mounting channels facing one another and a projection on each of said blocks being located adjacent to said wall; means securing said stems in lsaid slots; and an electrical heating element disposed in said mounting channels and extending therebetween, said projections adjacent said wall operating to maintain the heating element in a position spaced from the wall.
References Cited in the le of this patent UNITED STATES PATENTS 1,430,861 Tang Oct. 3, 1922 1,900,318 Van Valkenburg et al. Mar. 7, 1933 2,202,874 Smalley June 4, 1940 2,424,780 Trent July 29, 1947 FOREIGN PATENTS 500,799 Germany June 25, 1930 427,545 Italy Nov. 24, 1947 UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3,043,942 July 10, 1962 Theodore H. Wickwire III, et al.
It is hereby certified that error appears in the above numbered patent requiring correction and that the seid Letters Patent should read as corrected below.
Column 6, list of references cited, under "UNITED STATES PATENTS, add the following references:
Signed and sealed this 27th day of November 1962.
EETMEX DAVID L. LAD Attesting Officer Commissioner of Patents