CHAIRMAN'S ADDRESS - Coke Oven Managers Association

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A REVIEW OF C.O.M.A. ACTIVITIES, 1939-1945 - CLARKE 203.for control (such as finer grinding of the charge and adjustment of moisturecontent) were duly noted. Reference was also made to the reduction inpressure which could be achieved by the addition to the blend of dull coalof high durain content (a particularly effective material), or inert mattersuch as finely crushed coke, provided that these components wereintimately mixed with the charge.There was no report in the 1940 C.O.M.A. Year-Book of the extensivediscussion which followed presentation of Dr. Foxwell’s paper. For thisinformation it is necessary to consult the relevant pages of The Gas World(Coking Section), and I am indebted to Mr. Frank Lodge (a formerHonorary General Secretary of the <strong>Association</strong>) for kindly loaning me hispersonal copies of that publication, which have been used to prepare asummary of some of the points raised.The Chairman at the meeting (Mr. W.N. Warwick) referred to the greatdifficulties of simulating full-scale coking practice in laboratory studies,and hoped that practical investigations would follow from the workreported. He noted that some coals which were normally considered toshrink could occasionally cause difficulties in pushing, in spite ofsatisfactory wall-to-wall and cross-wall heating, and advocated the use of arecording ammeter to show the power required to initiate coke movementand to indicate the scale of any pushing difficulties. He also mentioned thepossible effect of the chosen oven schedule on any problems arising inpushing. Mr. Warwick considered it was desirable to test the individualseams of coal at the colliery supplying slack for the ovens, to assess anyvariations in swelling properties which might cause problems at the plant.Mr. A.H. Middleton, Mr. E.M. Myers, Dr. F.S. Sinnatt and Dr. J.H.Jones all considered Dr. Foxwell’s inclusion of Durham coals in thedangerous category was incorrect. Durham coals had been used forcokemaking for many years without any damage to the ovens, and largetonnages of this coal had been exported and used for coking abroad withoutany reported problems. Some clients particularly specified coal of thevolatile content stated by Dr. Foxwell to be in the danger zone.Considerable doubt was expressed by Mr. Middleton on the value of theKoppers laboratory-scale equipment in providing useful practicalinformation to guide the coke-maker. In contrast, Mr. B.E. Blackledgereported that in South Wales, at Margam steelworks, the apparatus was in
204. THE COKE OVEN MANAGERS’ YEAR-BOOKroutine use for coal testing, and also provided a useful guide to them indeciding the amount of dangerous coal which could be used in their blend.Particular attention was paid at Margam to the charge bulk density, evenwith a blend regarded as safe to carbonise, and the coal was crushed to giveover 90% through 1 / 8 ” mesh.Mr. H. Dean recalled his experiences with one South Wales coal whichbehaved normally on carbonisation until about the 14th hour after charging.As the plastic layers coalesced, the ascension pipe became partiallyblocked with material which was produced by swelling of coal on top ofthe charge. No damage was done to the brickwork and the charges pushednormally. The cure was found in reducing the height of the charge to allowthe coal to swell into the space above. Mr. Dean also mentioned hisexperiences with the Still internal suction process (see Bulletin, September1992, p.7) and noticed that on piercing the charge prior to insertion of thesuction tubes, a large volume of gas was released from the centre of thecharge. It appeared that plastic layers were formed almost immediatelyafter charging, and consequently a large internal pressure could beexpected at the start of carbonisation, but Dr. Foxwell’s graph had notgiven that indication.Mr. H.M. Spiers commented that some of the laboratory tests classifiedcertain coals as dangerous when they were being successfully carbonised inmodern high temperature ovens, implying that the criteria used forevaluation of the results or the methods adopted for the tests were at fault.Mr. Spiers considered the Nedelmann test was more likely to correlate withpractice, because in that apparatus the coal sample is allowed to develop itsown pressure, whereas in the Koppers laboratory test the coal is underapplied pressure throughout. Mr. Spiers observed that there is no directrelationship between the swelling characteristics of coals and their powersto generate pressure on carbonisation. Highly swelling coals of over 30%volatile matter seldom gave any indication of coking pressure at normalcharge densities, but the coals of 25-30% volatile matter were moredifficult to classify. Mr. Spiers said it was desirable that samples of coalsshould be assembled and tested, covering the range from undoubtedlydangerous through to those which were safe, together with informationrelating to carbonising conditions leading to development of dangerousproperties. He thought it might be possible to correlate the behaviour of thecoals with their ultimate composition.
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CHAIRMAN'S ADDRESS - Coke Oven Managers Association

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