US3456937A - Stove checker - Google Patents

Description

y 1969 F. A. BERCZYNSKI 3,456,937

STOVE CHECKER 5 Sheets-Sheet 1.

Filed July 6. 1967 m'IIIIIIIIIIIIIIIIIIIIIIIIIII I N VN TOR. F/eAA/K A. 35262 Y/V5K/ Arron/vans y 1969 F. A. BERCZYNSKI 3,456,937

STOVE CHECKER Filed July 6, 1967 3 Sheets-Sheet 2 OF TOTAL WEIQHT O .l .2 .3 .4 .5- -G -7 -8 -9 L0 DISTANCE FROM FLUE SURFACE (mcur-zs) IN VENTOR. Fm NA A. [BERCZ YNSK/ -MQ M A 7 TOR NE Y5 July 22, 1969 F. A. BERCZYNSKI 3,455,937

STOVE CHECKER Filed July 6, 19s"! s sheets-sheet a I NVENTOR.

PM A//( A BERCZ Y/VSK/ BY Ml 9 @eww United States Patent 3,456,937 STOVE CHECKER Frank A. Berczynski, Williamsville, N.Y., assignor to A. E. Anderson Construction Corporation, Buffalo,

Filed July 6, 1967, Ser. No. 651,594 Int. Cl. F231 15/02 US. Cl. 263-51 7 Claims ABSTRACT OF THE DISCLOSURE BACKGROUND OF THE INVENTION This invention is directed to heat exchanging checkerwork, and more specifically to a new and useful checker for hot blast stoves of a metallurgical furnace.

The heat capacity of any existing stove system is determined by .a number of factors, most of which are not subject to appreciable variations. However, often it is not feasible to scrap existing systems in favor of new ones. As a result, older stove systems continue to be operated at capacities materially below those obtainable with new systems.

- The capacity in a given system can be increased by decreasing the duration of its cooling period. Shortening of the cooling period, however, also shortens the time available to reheat the stove in most systems, thereby imposing obvious limitations on this method in the absence of a checker of increased effectiveness.

The heat capacity of a stove also could be increased by increasing the total checker Weight. One Way of doing this would be to increase the stove height. However, in most installations effective height increases cannot be added to the existing foundation. Stove diameter also is limited. Therefore, this approach usually is not available.

Heat capacity also might be increased by increasing the temperature level of the checker column. However, the refractory and checker column support material limit the maximum operating temperature obtainable with a given installation.

This leaves the possibility of increasing the effectiveness of the checkers themselves as a way of increasing the heat capacity of the stove. However, this poses a number of problems. The mass of a checker per unit volume is a measure of its ability to store heat. However, a fully effective brick mass is obtainable only if the temperature of the brick is constant throughout its wall thickness after heating and after cooling. In fact, a temperature gradient will exist, particularly during the cooling cycle, whereby it is not operationally possible to obtain one hundred percent effectiveness.

The effectiveness of the brick mass can be increased by increasing its temperature swing. Checker heating surface per unit volume is a measure of its ability to absorb heat and to give it up, and the heating surface area of a checker can be increased by using more but smaller flues. Also, a checker having thinner walls can be used, thereby increasing the temperature swing at the center of the wall, between adjacent flues. Another approach is to increase the proportion of the checker mass which is 3,456,937 Patented July 22, 1969 near a flue surface, the temperature swing being greate at the surface than at the center of the wall.

Checkers of increased thermal efiiciency have been developed, using one or more of these approaches. However, those of which I am aware have various disadvantages. In some of them certain walls are much thinner than others, and are relatively weak. Certain of them are intended to be laid up in a pattern requiring extra handling, and are relatively expensive. Also, so far as I am aware none of them is suited for the replacement of existing older checkers without substantial modification to the walls adjacent to the checkers.

SUMMARY OF THE INVENTION =One object of my invention is to provide a checker of high thermal efliciency which can replace at least certain conventional checkers without material alteration of existing stove structures.

Another object of my invention is to provide a checker characterized both by high thermal efficiency and by structural strength and integrity.

A further object of my invention is to provide the foregoing in a checker having a high ratio of heating surface to volume and a ratio of mass to volume in the range which has been found to be most effective. I

It is also an object of my invention to provide an improved checkerwork pattern requiring no extra handling.

The foregoing and other objects, advantages and characterizing features of my invention will become clearly apparent from the illustrative embodiment disclosed and described in detail herein.

BRIEF DESCRIPTION OF THE DRAWING FIG'URES FIG. 1 is a top plan view of a stove checker, constructed in accordance with my invention;

FIG. 2 is a side elevational view thereof; a

FIG. 3 is a graph showing the efficiency of a checker of this invention as contrasted with the range of efficiencies of those prior art checkers most commonly used in the United States;

FIG. 4 is a view in perspective showing checkers of this invention laid up in a checkerwork pattern of my invention; and 1 FIG. 5 is a perspective view of the checker of FIG. 1.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT There is shown in the accompanying drawing a stove checker of my invention, generally designated 1, c0mprising a rectangular parallelepiped of suitable refractory material. Checker 1 is formed with four central fiues 2 and a pair of open sided fiues 3 at the opposite ends thereof. Flues 2 and 3 extend through the checker 1 in parallel relation, at right angles to the planes of repose of the checker, as defined by its faces 4.

It is a particular feature of my invention that a substantial portion of the total weight of the checker is located close to a flue surface, and that a large amount of heating surface is present for the checker mass. For example, in the illustrated embodiment the checker has a mass of approximately 86.14 pounds per cubic foot, (based on 101.25 in. =8 lbs.) which is Well within the mass per unit volume range of 90 previously found to be most effective. It has approximately 12.85 square feet of heating surface, per cubic foot of checker as contrasted with the heating surface per unit volume ratios of 8-10 square feet per cubic feet of checker common to conventional checkers. Thus, substantially more heating surface is available and substantially more of the checker mass is positioned closely adjacent this heating surface. This is important because the gerater the percentage of total mass located near a heating surface, the greater the efficiency of the checker.

Referring now to FIG, 3, curves B and C show the relationship between checker mass and distance thereof from a flue surface, in illustrative prior art checkers, and taken together they define the range of such ratio provided by those prior art checkers most commonly used in the United States. Curve A on the other hand shows the ratio of total weight to distance from a flue surface provided by the checker of FIG. 1. It will be noted that curve A shows an efliciency substantially outside of and above the range of efficiencies as defined by prior art curves B and C. For example, with the checker 1 of this invention, well over 50%, and in fact approximately 60% of the total checker weight is within 75 of an inch of a flue surface. The most eflicient of the prior art checkers represented in FIG. 3, on the other hand, has between 45 and 46% of its total weight located that close to a flue which is of course a significant difference. Because more of the mass is positioned further from a flue surface in such common prior art checkers, more of the checker mass is subject to less of a temperature swing, with a resulting, relatively low efficiency.

In obtaining these results, the checker 1 is designed so that its flues 2 and 3 have substantially the same cross sectional area throughout. In other words, they are of substantially the same diameter, used in its broad sense. Also, they are arranged in parallel rows and columns, there being two flues to each column, making a total of four columns, and four flues in each of the two rows. Adjacent flues in each row and column thereof are spaced apart substantially the same distance, and this distance is substantially less than the flue diameter.

For example, the illustrated checker has a flue diameter of 1 inches (the flues being square with rounded corners) while the spacing between adjacent flues in both the rows and the columns thereof is .839 inch. This makes a total length of 7 inches and a width of inches, the length and width together totaling 13 inches and the length exceeding the width by 2 times the flue diameter.

The checker size is subject to variation, within limits, but the illustrated example is believed to be the most desirable because of its high efliciency and because it can replace certain commonly used existing checkers, without material alteration of the existing stove installation.

Further in accordance with my invention, the checkers 1 are laid up in generally a basket weave pattern. That is, the adjacent checkers in each course are arranged in right angular relation, as shown in FIG. 4. In this way, the side walls 5 of adjacent checkers close the open sided flues 3. At the corners of adjacent checkers, they combine to provide a free flue 6. In the course immediately above, the checkers are arranged in right angular relation to the checkers immediately adjacent thereto, in the course below. This is indicated in FIG. 4 where the checkers in the superposed course are denoted 1, otherwise being identical with the checkers 1 described above and illustrated in FIG. 1. Also, the checkers in the superposed course are offset one flue, along quadrature axes. In other words, they are not centered on the brick or checker below, in right angular relation thereto. Instead, they are disposed at a right angle and then shifted one flue lengthwise and one flue widthwise thereof. This is important because it interrupts the joints which otherwise would continue through the superposed courses.

Where the checkers must be modified to fit stove periphery, only a very simple modification, for example elimination of one or both sets of end flues, is required.

Accordingly, it is seen that my invention fully accomplishes its intended objects. While I have disclosed and described in detail one embodiment, that has been done by-way of illustration.

I claim:

1. A stove checker comprising a rectangular parallelepiped of refractory material having four central flues and a pair of open-sided flues at opposite ends thereof providing a total of eight substantially equally spaced flues of substantially equal cross sectional area arranged in parallel rows and columns, characterized in that. the spacing between adjacent flues in each row and column thereof is substantially no more than about 63.2% of the flue diameter and at least about half of said material is substantially within 0.3 inch of a flue surface.

2. A checker as set forth in claim 1, wherein the width of the checker plus the flue diameter equals approximately 6 /2 inches and wherein the length plus the width of the checker equals approximately 13 inches.

3. Stove checkerwork comprising a plurality of superposed courses of checkers as set forth in claim 1, adjacent checkers in each course thereof being arranged in right angular relation to each other to close said opensided flues.

4. Stove checkerwork as set forth in claim 3, wherein vertically adjacent checkers of superposed courses thereof are disposed in right angular relation, the flues thereof being alined.

5. Stove checkerwork as set forth in claim 4, wherein vertically adjacent checkers of superposed courses thereof are offset one flue along guadrature axes to interrupt the joints between adjacent checkers.

6. A stove checker as set forth in claim 1, wherein said checker has a mass per unit volume of at least lbs./ft.

7. A stove checker as set forth in claim 6, wherein said checker has at least 10 square feet of heating surface per cubic foot of checker.

References Cited UNITED STATES PATENTS 1,848,242 3/1932 Claassen 26351 2,451,392 10/1948 Kennedy 263-5l JOHN J. CAMBY, Primary Examiner

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