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30 MARINE REVIEW Pulverized Coal (Continued from Page 28) there may be times when the coal will be sufficiently dry before enter- ing the drier. In this case the coal is passed through the drier as usual, but the hot gases are eliminated. The coal discharging from the ro- tary drier is received by an elevator, and the spout leading from the drier to the elevator is usually equipped with a magnetic separator for the pur- pose of removing any “tramp” iron that may be in the coal. Tramp ning in a_ dust-tight, sand-sealed trough, the elevator and conveyor usually being driven by the same motor. The bins above the pulverizers should be big enough to supply the mills for two or three hours, thus permit- ting a steady feed and allowing some leeway in case anything happens to the drier or elevator drives. The pulverizing is done in various types of mills, but the most satisfac- tory and economical results are ob- tained with heavy ring-type mills, in which the pulverizing elements are forced against the ring by centrifugal January, 1926 numerous motor drives, since the dis- tance over which one flight can be op- erated is limited. Another conveying system consists of a pressure-tight tank, a source of compressed air, and a pipe line lead- ing from the bottom of the tank to the destination. In operation the tank is nearly filled with pulverized coal, sealed, and compressed air is then admitted above the coal, which forces the latter through the pipe line, discharging from the line into the furnace bins. In this system of coal transporting the disadvantages The Greatest Dry Land Sailor of His Time By John C. Acker pa VENNEMA, druggist of Menominee, Mich., has_ the blood of sailors in his veins and though he has never been to sea, yet the sea is the romance of his life. His father sailed out of Am- sterdam before he emigrated to Holland, Mich., in 1848, one of the original Dutch settlers. Peter was born 50 years ago. His early am- bition to go to sea was thwarted by his father. While he has nev- er been a sailor he is an intense and thorough student of all mari- time affairs. He knows the cap- tain, engineer, or some member of the crew, tonnages, dimensions, power, class, builders, and past and present ownership of all ves- sels on the Lakes. Seamanship, nautical history and marine bibli- ography are as familiar to him as the Latin abbreviations on a doc- tor’s prescription. He is a con- stant reader of Marine Review, the illustration showing him read- ing the October number. At the close of navigation the pharmacy is a great rendezvous for the men from the ships, and then Peter Vennema listens with eagerness and dreams of the life he has missed. t iron usually consists of iron spikes, splice plates, nuts, bolts, pick points, etc., from the mining operation. Some- times the magnetic separator is in- stalled ahead of the crushers instead of after the drier. It is very essential to keep iron out of the pulverizers, as it increases the cost of repairs and causes delays. These magnetic separ- ators are usually of the lifting type although in some installations the pulley is used. The elevator used for delivering the dried coal to the bin above the pul- verizers is of the chain-and-bucket type, and steel encased to eliminate dusting. In some cases the elevator discharges directly to the bins above the pulverizers. In other cases it dis- charges into the screw conveyor run- rr iii =i force. These particular mills take a feed of 1l-inch or 1%-inch material and discharge it at the required fine- ness. Their superiority is based upon the combination of high fineness pro- duced, large capacities, low power con- sumption, and low maintenance charges. Transporting Pulverized Coal When the coal has been pulverized, it must be transported to the point of use. A number of methods are available, the oldest being the spiral screw conveyer, operating in dust- tight steel troughs. This type of con- veyor, as it is hard to keep clean, is dangerous unless given proper at- tention, and requires considerable power, overhead runways, and often of the screw conveyor are eliminated, but other faults are discovered, these being that more labor is required in the operation, that the coal must be accepted and discharged in batches, and that the large volume of air re- quired makes cyclone dust collectors at the discharge end essential. A third system, which is rapidly coming to the fore, consists of a pump having as an impeller a high-speed steel worm, which takes the pulverized coal from a hopper and forces it into a pipe line. A small amount of com- pressed air is admitted into the ma- terial: just beyond the discharge end of the worm, and the mixture of air and coal is forced through the pipe line to the destination. The worm is (Continued on Page 88) PL OES Ra TT Te IN poe A