Document kJ9ZKbJvbQ6a4k4D7JznV10

H. W. Burleson - DEQ . Division Heedquartero March 25, 1968 April 1st cutitlad, "Bscent Improvements in Blast Furnace Stove Design" by Hr. Frank A. Bercsynski, Vice President of Engineering,, A. E. Ander son Construction Corporation, Buffalo, New York. Mr. Debenhan further advised that there were ease rather alarming disclosures in this paper regarding stove insulations. He requested that we tscet with him to discuss this farther. Claire Harohaw, Sid Evans set with Hr. Debenhaa, John Topping, Mr. Debenhsa's assistant, and Mr. Bill Metsger, Blast Furnaco Design Engineer. They were all quite frank in saying they were quita concerned by sees of the information contained in this paper. Sot only because the great majority of their stoves arc insulated with cur SDFSESZ? bar. also because they are, at the moment, in the final stages of planning their newest and the largest to date blast furnace at the Gary Indiana works. They arc therefore very anxious for our comments on the information presented and our recommendations for a solution or alternative. Incidentally, they all spoke very highly of the author of this paper and he has apparently bad many years experience In this business, not only with his present connany, but with the John Mohr & Sons Company of Chicago: Mr. fi-lv-nhgTn gas kind enough to have a copy of the paper made for am and in reading over it, it is obvious that it*is the result of many paosQ experience and much work. The paper, incidentally, is 30 pages long, with. 17 pages of charts end diagrams. Page 2 Sines I will not have an opportunity to have copies made nor discuss this vith you, I would like to quote soma porticos of the paper for your consideration end advice. They will make plans to attend the A2MB Meeting and would hope to be prepared to ask same questions and hopefully offer some alternates to Hr. DebenKsm. Unfortunately however, since we are tied up all this cooing week with cur sales meetings, it is going to he very difficult to do very much. The following are excerpts which, I beliave, cover oo3t of the key points made by the author. "Since about 1958, average stove refractory operating temperatures have been increasing. Accompanying this increase has been a period of un expected stove shell failures, ranging frea 360 horizontal cracks in the stove shell, opening gaps of 1/2" to 1", to severe bottom plate dishing; the latter at times resulting in premature stove bottom plate failure.--Stove Systems experiencing difficulty had one thing in coenon, 1. e., the stove linings. In some cases new and in some cases old, were being operated at desas teeparatures higher than that employed prior to the difficulty. The problem was, therefore, related In sane way to temperature." (The author continues here for 2 pages describing assumptions that were made in the past regarding expension, its effects and provisions made to allow for it. He than states that he feels this matter needs a reevaluation with today's operating conditions.) "The majority of stoves in service throughout the U. S. utilizes insulating material between the stove ring or pilaster wall and shell which have compressibility characteristics similar to materials 1 and 2 shown in figure 11. (Assume to be curves on SUPZH2X and 17 Block.) It can be shown theoretically that the range of insulation compression required for cost staves in the U. S. operating at docs temperatures of 2300 F is approxi mately 5Z to 10Z - tho specific range being a function of stove diameter in refractory materials. At these percentages, the radial shell pressure can be as high as. 125 p3i, assuming the shall does not yield under these pressures." 'The pressure created by the radial expansion of the refractory, coupled vith their vertical expansion, raises the shell or creates e high axial stress if the shell is sufficiently restrained, through the friction that exists between tho insulation and the stove shell."(A chart Illustrates these forces) -- "In mast stoves In the U. S. operating at dome tempera tures of 2300 F,' tills "frictional drag stress" is in excess of 30 times the combined axial stresses resulting from shell dead load, wind, thermal differentials, and internal pressure.-- A eloSe examination of the factors contributing to the "frictional drag stresses", indicates two possible economical methods of reduction. The friction factor, , could be lowered; or F,the forco due' to pressure could be reduced by using a acre compresslblo Insulating material. The latter 13 most desirable since the accurate deter mination of the friction that exists between She materials in a hot blast Page 3 ctove Is operating conditions is not extremely reliable. Until recently, a suitable insulating material with the temperature and compressibility characteristics necessary to accomplish the reduction of the radial pressure force, P, at reasonable costs did not exist. New mineral wool insulating materials can now be obtained from most major refractory manufacturers with tbe necessary properties. Figure 11 shews the percentage of deformation versus pressure characteristics for one such material, for 2 different thicknesses. -- "Figure 13 compares the thermal conductivity of a typical mineral wool Insulation suitable for stove application with conventional insulating materials 1 and 2. As far as recovery is concerned, a 7" thick sample of mineral wool block insulation was subjected to a 10% deformation in 10 minutes. The sample returned to a thickness of 96.5% of the original thickncsB.--"Several stoves have bean installed with highly compressible mineral wool insula tions. The oldest of these insulations has been in service since 1964. These stoves have esparienced less than 1/8" total movement of the bottom plate, eaximm movement occurring at the dome temperature of 2300 F, and ambient teeperature of OF." This is basically his story. It certainly appears from the facts pre sented that there is a need for scan means c absorbing the expansion and reducing the "frictional drag stress". However, I certainly don't think the answer is replacing SUlrfiRgX with any mineral wool block that I know of and U. S. Steel people are of this same opinion. However, it does appear that seme composite type of material might well be in order combining the temperature resistance and stability of SUFEREX and the compressibility or resilience of a fibrous material on the cold or shell side. IQthink ws should, at once, determine if we can laminate SCFESEX and 1C00 Spin-Glas or 400 Series Spintex to offer for this application. Regarding the mineral wool material mentioned in the paper, at this point I don't know what material customer is referring to, but I don't know of any great improvement in these materials by any of our competitors and certainly none that I know-of is suitable for a hot face temperature of 1900 F and certainly does not have the resilience described in the article after being heated end I'm convinced U. S. Steel people, at this point, feci the same way. However, I feel this paper is going to have great impact and we must be ready with seme answers if we are to maintain our position in this field. 1 would like to discuss this with you and all concerned et Research on Thursday. J. A. Campbell, Jr. rer-8