xc/EPA United States Environmental Protection Agency Industrial Environmental Research Laboratory Research Triangle Park NC 27711 Research and Development EPA-600/S2-82-066 August 1982 Project Summary Development and Demonstration of Concepts for Improving Coke-Oven Door Seals: Final Report A. 0. Hoffman, A. T. Hopper, and R. L Paul The report discusses the design, laboratory scale tests, construction, and field tests of an improved metal-to-metal seal for coke-oven end doors. Basic fea- tures of the seal are: high-strength tem- perature-resistant steel capable of 3 times the deflection of current seals without permanent deformation; no backup springs and plungers and the at- tendant requirement for manual inser- vice adjustments,' seal installed to con- form to the jamb profile; seal lip height reduced to give 8 times the inplane flexi- bility; and compatibility with existing coke batteries and door handling machines. Field tests on operating 4 and 6m batteries proved the soundness of the concept along the straight vertical sides of the door. However, an unfore- seen force combination in the four cor- ners resulted in a net force acting to lift the seal corners away from the jamb, re- sulting in unacceptable leakage at each seal corner. Various schemes were eval- uated empirically in an attempt to under- stand and solve the problem. A modified design to eliminate the problem and re- duce fabrication cost is proposed. Inland Steel Company plans to build and test the modified design at its own expense. This was a jointly funded EPA/American Iron and Steel Institute project. This Project Summary was developed by EPA's Industrial Environmental Re- search Laboratory, Research Triangle Park, NC, to announce key findings of the research project that is fully docu- mented In a separate report of the same title (see Project Report ordering infor- mation at back/. Project Origin In 1975 Battelle completed a project entitled "Study of Concepts for Minimiz- ing Emissions from Coke-Oven Door Seals." This project was jointly spon- sored by the Industrial Environmental Research Laboratory of EPA and the American Iron and Steel Institute (AISI). The results and recommendations of the 1975 study were accepted by both sponsoring organizations and late in 1976 Battelle was awarded research contracts (with EPA and the AISI) deal- ing with development/engineering/lab- oratory evaluation of the recommended, upgraded metal seal. The results of this effort were accepted by the sponsors and funding was made available to com- plete Phase III of the program which con- sisted of fabrication and field demonstra- tion of the recommended seal design/ material. This Report This report summarizes the entire ef- fort to develop an upgraded, retrof ittable, metal coke-door seal. "Upgraded" here is defined as having significantly im- proved performance in emission control and operation. ------- Not included in this report are results of a major effort to prevent/minimize warpage of coke-oven jambs by changes in the jamb design and materials. This work was, however, reported in the EPA report, "Development and Demonstra- tion of Concepts for Improving Coke- oven Door Seals: Interim Report," EPA- 600/2-78-189 (NTIS PB No. 286 628), August 1978. The Recommended Seal Design/ Material The recommended seal design was the result of finding a best "fit" as eval- uated by a long list of criteria and specifi- cations. In a systematic approach, each criterion had to be considered, but the two major influences on the design were (a) a general specification by the AISI and EPA, and (b) a criterion strongly de- sired by Battelle researchers. The major specification was that the new seal be retrofittable, i.e., the new seal would be a replacement for existing seals without modification of the doors or the door-handling equipment. This also meant that the recommended seal had to "handle" or accommodate all (or nearly all) of the jamb and the door warp- age problems that exist at operational plants. Seals are attached to doors and the profile congruency of the door with the oven jamb can be poor due to past warpage and heat effects. The criterion desired by Battelle per- sonnel was that the recommended design/ material should eliminate the need for numerous, manual seal-adjustment de- vices associated with all existing seals. With about 25,000 coke-oven doors in operation, each with about 20 manual seal-adjustment devices, the theory is that at times workers climbing ladders or scaffolds would adjust 500,000 de- vices to improve emission control. Bat- telle researchers were skeptical about the performance of the adjustment de- vices and the availability of the time and skill to manipulate them. The general approach to an upgraded seal was to increase the seal flexibility in every way possible while also increasing its strength and heat resistance. This ap- proach resulted in the recommended de- sign shown in Figure 1. The design/material elements leading to increased flexibility and strength are: 1. The height of the contacting edge [(A) in Figure 1 ] was lowered to a 9.5-mm height (from 19 mm) to in- crease the flexibility of the edge along the jamb by a factor of 8. This increased flexibility allowed the Sealing Ring (B) Figure 1. Cross section of a suggested coke-oven seal. vertical seal edge to maintain con- tact with the jamb in spite of curva- tures in the jamb surface and the uneven surface of the seal edge. . The main spring element [(B) in Fig- ure 1] was switched from 304 stainless or a corrosion-resistant, low alloy steel to a high-strength, high-temperature spring alloy. Bat- telle recommended that the first demonstration seals be made of age-hardened Inconel X-750. In laboratory tests at 426 °C (800 °F), Inconel X-750 tolerated three times the amount of seal deflection dur- ing simulated door latching before plastic distortion by creeping was encountered. Increased seal deflec- tion is desired to (a) absorb minor changes in door and jamb profiles without the need for adjustments, and (b) keep an evenly distributed force pressing the seal edge against the jamb. 3. Changing the width of the spacers [(C) in Figure 1] along the door made it possible (during original seal mounting) to bend the entire seal to make the profile of the seal edge match the general profile of the jamb. This element of flexibility was introduced to make it possible to realign the seal edge and jamb profile in instances where the door and jamb profiles are particularly incongruent. This design eliminated the need for seal- adjustment devices (and backup springs) ------- pressing in point loading against the out- board side of the seal. Demonstration Seal Fabrication Two of the criteria for judging seal designs were (a) whether the design was amenable to mass production methods, and (b) whether the machining during fabrication could be eliminated. For the design presented, Battelle recommend- ed (1) roll forming the seal shape rather than one-at-a-time brake forming, and (2) hydroforming the corners rather than the cut-fit-weld-machine fabrication me- thods now being used. Further complications were intro- duced by (1) the requirement that de- monstration seals should be obtained from experienced seal fabricators, rather than jobbing fabrication to different shops; and (2) introduction of a seal- corner design that could be fabricated only in a hydroforming operation. Eleven months after sending out re- quest for quotation seals, four seals were delivered to the Bethlehem Steel coke plant in Lackawanna, New York. Results of the Seal Demonstration Efforts The recommended seal design/material was tested at Bethlehem Steel's coke plant in Lackawanna, New York (6-m Wilputte battery) and at Republic Steel's coke plant in Youngstown, Ohio (4-m Koppers batteries). At Lackawanna, the usefulness was demonstrated of taking simple measure- ments of the variation in distance be- tween the jamb and door (along its length) and then installing spacers under the new seal to bring the seal edge into congruency with badly warped jambs. In one instance it was necessary to put a 1 9-mm (%-in.) steel bar under the top horizontal portion of the seal to bring the profile of the seal into alignment. Zero leakage, increased flexibility, and no manual adjustments were demon- strated (for months) along the 6-m ver- tical sides of the seal, as expected. However, all four seals put into opera- tion unexpectedly released emissions through gaps at each corner. This prob- lem persisted even after reworking one seal to eliminate variations in the flat- ness of the seal edge. It was deduced that the corners were "lifting off" the jamb; i.e., the corners were reacting to forces that act to cause a slight gap at the corners during seal deflection. This lift off effect was confirmed at Republic Steel during tests using a 4-m seal forced against a flat machinist table. The fact that corners on seals can re- act counter to a desired pattern was not new—U.S. Steel research personnel had told Battelle about "corner lifting" they had encountered on standard seals. What was obvious was that (a) the design changes made to avoid this potential problem were not successful in full-scale operation, and (b) that Battelle's labora- tory work on parts of the seal did not model the reactions in complete seals. Experiments at Republic Steel indicated that the seal lip was not part of the prob- lem and that some method had to be found to relieve the "bunch-up of metal" that occurs during seal deflec- tion in the flat portion of the seal in the corners. The Modified Seal Design Project originators did not anticipate that a considerable amount of problem solving would be required after getting the first demonstration results. Although continued analytical work was consid- ered (modelling and strain gauge testing on a full-scale seal), the last emphasis in the project was to consider the range of design changes that could provide ah empirical solution to the corner problem. Out of this approach came a modified seal design (not yet tested). This modi- fied design is shown in Figure 2. The major elements are: A— a flat strip, cantilever-spring re- placement for the formed S-shape used in the original design. B— a heavy-section, carbon-steel, angle-iron seal holder. C— a demountable seal-edge angle bolted or welded to the seal ele- ment (no machining required). It is recommended that the spring por- tion of the seal be made of 1 7-4 PH stainless steel, rather than Inconel X-750. This lower priced alloy was not included for consideration in the original evaluation because it is difficult to form, but all forming is eliminated in this design. It is expected that this seal can be built by steel companies. For an empirical approach to a solution of the corner problem, it is suggested Door Back Figure 2. Modified seal design. « U.S.aOVEBNMINTWIINTIM30FFIM:1»U-S59-Ol7/0784 ------- that the strips making up the main por- tion of the seal only be butted at the cor- ners, not welded. This leaves a space or separation in the corner that (a) makes the corner relatively flexible, (b) permits consideration of corner backup (springs) outboard of the corner to force the cor- ner against the jambs, (c) may minimize some of the stress generation in the cor- ners during deflection, and (d) could in- troduce a built-in emission problem in the corners. To prevent emissions through the spacings, it is suggested that this space be closed with a cover strip (or foil) attached outboard of the corner. Present Status of the Modified Seal Inland Steel has volunteered to engi- neer/fabricate/test and oven-demon- strate one seal of the modified design. At this time, engineering is complete and fabrication is in progress. A. 0. Hoffman, A. T. Hopper, and R. L. Paul are with Battelle-Columbus Labora- tories, Columbus, OH 43201.' Robert C. McCrillis is the EPA Project Officer (see below). The complete report, entitled "Development and Demonstration of Concepts for Improving Coke-Oven Door Seals: Final Report," (Order No. PB 82-230913; Cost: $12.00, subject to change} will be available only from: National Technical Information Service 5285 Port Royal Road Springfield. VA 22161 Telephone: 703-487-4650 The EPA Project Officer can be contacted at: Industrial Environmental Research Laboratory U. S. 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