May 11, 1917. THE COLLIERY GUARDIAN. 897 COKE-MAKING PROBLEMS AND THEIR SOLUTIONS. Addressing the members of the North of England Gas Managers’ Association, at their annual meeting in Newcastle on Saturday last, on “ Some War Time Alterations of Works,” Mr. H. E. Bloor, B.Sc., B.Eng., gave much interesting information as to the solution of coke works difficulties. He said the scheme he had carried out at the York Gas Works did not represent in any way his solution of the problem of carbonisation, either in principle or detail. The works were divided into two parts by the River Foss, and connected by an overhead railway. The carbonising plant in the newer portion consisted of 12 direct-fired settings, each setting having eight oval retorts with circular mouthpieces. Although the retort house was a very fine building, the bad foundation and other considerations rendered it impossible to re-construct the carbonising plant on modern lines, and the house was accordingly placed out of action, and attention concentrated on the old works. Contracts were placed with Messrs. W. J. Jenkins and Company Limited, Retford, for a combined stoker, coal breaking, and elevating plant, consisting of a Jenkins breaker of 50 tons per hour capacity, fitted with a wipe-off automatic feed. A small hopper, 7 ft. square at the ground level, centrally situated under the overhead rails, supplied the feeder, which was pro- vided with in. square holes, which partially screened the coal. The breaker and elevator were belt-driven. The elevator was of the ordinary bucket type, with a capacity of 50 tons per hour, and was practically a D.B. chain with buckets attached. It had given every satisfaction, working with perfect smoothness and noiselessness. That form of construction was a marked improvement on the usual skidder-bar design. It was 61 ft. high, and, with the breaker, was driven by a 29 horse-power motor. The local circumstances pre- vented the adoption of continuous coal hoppers, and two separate hoppers were installed. A small hopper, holding 30 tons, was decided upon for the direct delivery from the elevator, whilst a 70-ton hopper was provided at the middle of the building, served by a belt conveyor 24 in. wide, carried exter- nally on the roof principals, and housed in a wooden tunnel. The combined ,D.B. stoker was of the usual type, and no trouble had been experienced with the charger. The De Brouwer hot coke conveyor was 3 ft. wide and 334 ft. 8 in. long, with flat push bars of . cast steel. It commenced to rise at an angle of 35 degs. at the end of the retort bench, delivering into a screen 3 ft. 4 in. in diameter by 26 ft. long, revolving at 12 revolutions per minute. Three separate sections of the hopper were provided, to take the screenings through f in. and 1J in. mesh and large coke, but the intermediate size had been temporarily abandoned, and only breeze and large coke were now made. Some few complaints of the smallness of the coke had been received. The trouble was twofold. It was neces- sary practically to empty the hoppers every shift. The first lot of coke from the following shift fell the full height, and it was only when the hoppers were half- full that the coke could be said to be reasonably treated. Secondly, he was satisfied that a consider- able separation of the large pieces took place in the act of falling, and, at certain times, the whole of the coke drawn from the hoppers was in large lumps. He believed that the breakage could have been greatly reduced had the hoppers been much larger, so as to obviate the necessity of starting each shift with a clear hopper. As originally designed, the coke shoots to the hoppers were double, but at an early stage the use of the long shoots filling bags at the floor level and lifting on to lorries was found unsatisfactory, and the coke also tended to hold up in the shoots. He accordingly designed and made coke shoots of a new type.’ These were roomy, and operated by a simple lever working a slide. The shoot was very accessible, and coke could be released instantly by the operator if any holding-up occurred. The height was suitable for loading carts, and the bags were filled on a wheeled platform placed immediately below the shoot. There was thus no lifting up of bags, and the bagging was very rapid and easy, and was performed by women, with the assistance of a one-armed male employee. Thirty bags could be filled and loaded, and the cart be ready for weighing in from five to six minutes. A small point in the design of the conveyor was worthy of notice. Owing to the fact that each setting had two producers, it was necessary to wheel coke to fit the machine side producers. In order to provide a supply of coke within the retort house, the conveyor was provided with a flap door at a suitable height, and coke could be dropped on the floor or direct into hand carts. In practice, it had been found impos- sible to feed the producers on the conveyor side .with coke direct from the conveyor, owing to the design of the producers and feeding doors. Cold coke was, therefore, used throughout. As originally designed, the coke conveyor was drained through a perforated cast iron plate into a sump, the clearing of which was a source of trouble and expense. He had altered the arrangement, and the water now drained from the side of the trough, and ran direct to the drains by’ way of a shallow channel constructed of two courses of bricks, and provided with a few perforated trans- verse plates. The system answered perfectly, and the channel was emptied daily without expense by the retail coke man. The dust was used up in the producers. The coke appeared to require a large amount of slacking, and the use of a large number of sprays was so wasteful of water, that he experimented with several automatic sprays, and ultimately one was evolved which he considered entirely successful. The tap used was of the gland variety, as all ordinary plug taps were found useless owing to leakage, and a hoop lever had been found less liable to foul the coke. The spray was formed very simply by means of an adjust- able cone in a short piece of 1 in. pipe. It could easily be cleared, and the cone of water made to fit the trough perfectly. He attributed to that spray the fact that, so far, there was no sign of unequal length- ening of the conveyor, the bars of which were still at right angles to the trough. On one occasion, the chain ran out of the tension wheels of the coke conveyor, but a safety device, operating when the wheels fell an inch, and designed to catch the shaft of the floating pair of wheels, had now been fitted, rendering such a breakdown impossible. The coke hoppers were constructed of mild steel throughout, supported on cast iron columns, and, in view of the visible wear on the bottom plates, he was arranging to line the hopper bottoms with cast iron plates J in. thick, and bedded in cement. The coke gantry was specially designed to meet the peculiarities of the site and works. The only avail- able coke store was a long narrow yard between the retort house and the boundary wall. In that area were four wells — two long rectangular and two circular. The coal store ran at right angles to the retort house, and extended to the boundary wall. It was desired to take advantage of that to enable coke to be put into wagons or into stock as required ; and an overhead electric railway was installed, running along the hopper side, and thence right through the coke yard and into the coal store at a suitable height to fill ’ railway wagons on the same line of rails on which was the coal tipping point. The electric loco- motive was of 15 horse-power, the gauge 24 in., the gradient 1 in 18, and the length of track 431 ft. The current was taken from two trolley wires, supported by brackets bolted to the joint carrying the rails; but that arrangement had been unsuccessful, owing to insufficient clearance between the wires and to weak- ness of the brackets, easily bent; and it was proposed to replace the whole arrangement by overhead wires. The locomotive readily pulled two bogies, each loaded with 10 cwt. of coke, up the incline, and, when the locomotive had been loaded and provided with stronger brakes, it was intended to handle three bogies. A round journey occupied five minutes. About 2,000 tons of coke could be stored, with a little raking, down, and it was hoped in future to dispense entirely with the expensive cartage and stack in the other works which- had always hitherto been unnecessary. The electric power was obtained on special terms from the Corporation. The current was 460 volts direct. After describing how the troubles .caused by stopped ascension pipes had been overcome, the speaker dealt with improvements to the tar scrubbers. These, he said, were worked in a peculiar manner, the weak liquor running into a small sump and overflowing to wells situated a considerable distance away. Liquor for the first scrubber and the Livesey tar washers was pumped from a sump filled by gravity from the tar wells, and liquor ran direct back to the wells. With that system, it was impossible to work up the liquor to a satisfactory strength, and the capacity of the scrubbers was only from 1,000,000 to 2,000,000 cu. .ft. per day. It was a peculiarity of the works that, although the carbonising plant was capable of an output of 2,000,000 cu. ft. per day, the subsidiary plant was designed for only about 1,000,000, so that it used to be necessary to run both works for six months in the year. The system of connections was altered so as to permit of working the old works retort house to its maximum capacity, and utilising the new works purifier. A necessary preliminary was to render the old works ammonia plant equal to the full production of the retort house, and that was effected by the construction of a set of three small wells, each 6 ft. by 4 ft. by 6 ft. deep. The fresh water scrubber was now provided with a set of sprays half-way down through which liquor was circulated from the first well. The overflow from that well (equal to the fresh- water supply) went into the second well, which sup- plied the first scrubber, and the overflow from the third well was circulated through the tar washers. The system would now comfortably deal with 2,000,000 cu. ft. per day, so far as the scrubber and washer capacity was concerned, but the small connec- tions gave considerable back pressure. Before 2,000,000 cu. ft. per day could be dealt with continu- ously, it would be necessary to deepen the siphons still further. The liquor from the condenser ran direct to the wells at present, but arrangements were almost complete for passing that liquor into the first scrubber well, so that its value for purification might be utilised. The carburetted water-gas -plant was situated in the new works, and consisted of two sets of a rated capa- city each of 750,000 cu. ft. per day. He had recently replaced the ordinary form of chequer bricks in one of these machines with the Davison-Tooley patent brick. The reduction of pressure due to that type of brick was such that the altered machine was now capable of moving 900,000 to 1,000,000 cu. ft. per day with 17 in. blast pressure. DISCUSSION. Mr. C. Drury (Sunderland) said that, as to coke hoppers, they had a series of steel hoppers both for coke and breeze, and, especially in the latter case, the destruction of the plates had been very severe. They found effective results following from reinforced con- crete lining, with which there was apparently no attrition of the surface at all; it merely became polished. Mr. T. Hardie (Newcastle) said that his firm had adopted the De Brouwer conveyor a good many years ago. As to the breeze, they came to the conclusion that the increased quantity obtained from the ' De Brouwer conveyor was largely due to the rotary screen. Some years ago they did away with that screen altogether, and substituted a system of bars which took out the coke, he thought, just as effectively as the rotary screen, and, he was sure, reduced the quantity of breeze formed. The slacking of the coke was a difficult problem with all class of coke handling machines in the matter of getting the coke properly quenched without getting it too wet. His firm erred on the side of keeping it dry, with the result that on several occasions they had had fires in their coke hoppers. He was sure that the method of spraying the coke as it passed in front of the retorts was the right method. Mr. A. C. Hovey (Newcastle) was pleased with the shoot for bag filling, because coke was difficult to handle, as it had to pass by gravity from one point to another in an enclosed vessel. Mr. Bloor certainly seemed to have devised a very cheap method of deliver- ing coke in bags—which was recognised as being a costly business. He, himself, had to do with water spraying with a gland cock some 15 years ago, and believed that it was still in use, but, instead of having a single spray, there was a secondary spray, so that no attempt was made to swamp the coke with water at one point, but a further smaller supply was brought into contact with the coke at a high level arranged just above the curve on the incline. As to the belt-driven breaker, it seemed to him that the same result could be achieved by a fuse in connection with the motor. With reference to the accident in connection with the tension gear, he thought it was almost invariably arranged that a stop should be put at a certain dis- tance below the balance weights, so that, if there was a breakage of the chain, it did not fall any distance or do any great damage. With a central link chain he thought the accident of the coke falling could not occur. Mr. Bloor, replying, said there seemed no doubt that some of the coals used were particularly likely to cause stopped pipes. The cause was difficult to ascer- tain. Whether it was that carbonisation took place much more quickly, he did not know. He believed that two of the coals used—quite satisfactory gas coals, and both coals that made a bad coke, a thing that seemed to go with stopped pipes—were particularly likely to give trouble. One of the difficulties he found with the De Brouwer machine was the impossibility of preserving quite uniform changes, particularly when different coals were used. Whether a man could manage it with one sort of coal, he did not know. The cost of the coke gantry was about £1,390, he thought, exclusive of foundation work, but including the cost of locomotives and bogies, structure, cross joists, and all the gear for opening the shoot. There was a small extra for roofing. UNDERWATER COAL STORAGE. Following the reference to the constructional work on the coal storage pit of the Duquesne Light Com- pany, of Pittsburg, which appeared in our issue of September 1, 1916, some additional particulars are to hand regarding the actual dimensions. From these, it appears that the pit will measure 150 ft. by 800 ft. (25| ft. deep), with sides sloping at 45 degs., and the holding capacity is estimated at 100,000 tons of coal. The pit, which is said to be the largest in the world, is close to the main generating station of the company on Brunot’s Island, and the danger of spon- taneous combustion will be prevented by submerging the coal in water up to the top of the pit. The con- crete lining was laid in blocks measuring about 40 ft; by 50 ft., separated by construction or expansion joints waterproofed by pitch and tar paper above a 12 in. base of concrete 4 ft. wide. In lining the side slopes travelling structural steel frames were used to support the unit timber forms. Another special feature was the method of overcoming the difficulty of keeping the 1 in. expansion joints clear while the slabs were being concreted. The reservoir extends 153 ft. at the top, with a width of 791 ft. The floor is paved with concrete 15 in. thick, reinforced by two layers of expanded metal, while the 45 degs. slopes on the inside of the embank- ment are paved with concrete reinforced by expanded metal. The thickness of the side slopes varies uniformly from 20 in. at the bottom to 8 in. at the top, and the pieces used are cast monolithically with a bottom section 10 ft. wide, curved reinforcing rods being employed at the in-section. The outer slopes of the embankments are protected by riprap built up of stone. In order to submerge the coal, a supply of water is pumped into the reservoir through a 14 in. cast iron pipe line leading from the power house to four 12 in. cast iron outlet pipes placed about 160 ft. apart in plan and about 6 ft. below the top of the reservoir. Valves permit the water to rise inside the pit as the river rises in times of flood, the normal water elevation being at the level of the 15 in. concrete floor of the pit. A central concrete plant on the river bank adjacent to the work supplied concrete for the pit, and also for the construction of two large intake wells which were being built at the same time about 100 yds. away. Gravel and sand were brought by barge, and were hoisted directly into a bin with a capacity of about 150 yds., which fed a J yd. mixer. The concrete was elevated from the mixer by a tower, and a portion placed directly in position by a system of chutes, while the remainder was loaded into specially designed side- discharge cars and transported to points from which it fell into place by chutes. A special steel travelling form consisting of six trusses resting on rollers and travelling on single rails, one at the top and the other at the bottom of the slope, was employed to retain the concrete on the 1 to 1 slope. The face forms proper were made of wood in removable panels about 3 ft. by 10 ft., and were attached to angles by lugs, the angles being suspended from the trusses by rods having turn- buckles to provide for adjustment to the proper align- ment. Trade Opening Abroad.—A Johannesburg firm desires agencies for solid drawn or welded steel pipes, mining trucks, and safety fuse and detonators. United Kingdom manufacturers may obtain the name and address on appli- cation to the Department of Commercial Intelligence, 73, Basinghall-street, London, E.C. 2. The reference number (158/19) should be quoted.