GRANARIES AND GRAIN ELEVATORS. With the disappearance of the old type of granary, the term grain elevator has in the United States and Canada almost wholly ousted the older term. A modern granary, with its elaborate organizations, may be likened to a scientific development of the fundamental theory laid down by Joseph of Old in Egypt. In modern civiliza tion granaries play probably the most important part in the world's economy, since they are instrumental in distributing the daily bread from the sparsely populated new countries where production, on the virgin soil, is greater than the consumption, to the densely populated old countries, where conditions are re versed. Beyond the obvious purpose of providing safe storage, modern granaries provide automatic handling for the grain to and from storage with a maximum of speed and a minimum of cost. An outstanding advantage of the system is that a farmer can store his wheat or maize at a moderate rate and can get an advance on his warrant if he is in want of money. Moreover, a holder of wheat in a Chicago granary can withdraw wheat of similar grade from one in New York, thus saving freight. America is the home of great granaries, which are called "ele vators" in that country, but it is not generally known that a certain Robert Dunbar, a native of Carabee, Fifeshire, Scotland, designed the first modern type of granary at Buffalo, where he had settled in Granary Building Materials.—Until within a few years of the close of the 19th century silo granaries were in vogue, built of timber on the crib system, somewhat after the fashion of block houses; the silos, however, were of sawn timber, generally about I2ft. square, and the planks were nailed one on top of the other overlapping at the corners, beginning at the base with those of 6 to loin. width, and finishing at the top with those of 4 inches. This construction was quite satisfactory, but the high cost and growing scarcity of timber necessitated the use of other materials.
During the opening years of the loth century cylindrical steel silos were built with conical or flat bases, the former being con structed of steel and the latter of concrete. This type of granary is comparatively cheap and the weight of the structure is light relative to the amount of grain stored. Formerly all steel silos were built with riveted joints, but bolts are now largely used, the cost of erection being thereby considerably reduced, since skilled riveters are no longer required to put the tanks together on the site. Steel was soon ousted by tiles reinforced by steel rods for square silos and rings for circular ones. The concrete type of granary is the most recent and by far the most satisfactory form of construction, and the majority of large granaries built of late years are of this type. They are proof against both tire and vermin and have the advantages of utility, longevity and economy.
Granaries are built with what is known as a cupola which is erected above the silos; in the early days this, too, was built of timber. It consists of one or more working floors where the ele vator tops and the band conveyors are located and manipulated. Nowadays these cupolas are also built of ferroconcrete.
The development in the mechanical equipment since 1896 must be likewise recorded. This is in keeping with the general progress in engineering practice by which all industries have more or less benefited during the period in question. It is now customary, with the advent of the individual motor, to drive each conveyor or elevator unit by a separate motor through silent chain and double helical speed reduction gear instead of, as formerly, all machines being driven by means of ropes and countershafts from one prime mover on the ground floor. This means great saving of space, increase of storage room, altogether greater compactness, convenience of operation with a minimum of manual attention and better facilities for dust elimination. The very latest im provement noted is the employment of roller bearings on all of the machinery.
At the No. 3 Montreal Granary, where all these mechanical im provements are in use, a saving of one-third in driving power has been effected over all of the earlier and the more cumbersome methods.
While the developments enumerated above have improved the general condition of granaries, they have incidentally reduced the risk of explosion by lessening the possibility of producing static sparks. The introduction of roller bearings has minimized the danger due to overheated bearings, and the increased size of main-bucket-elevator head-pulleys has practically excluded ele vator chokes with their inevitable production of dust.
It has only recently been fully recognized that granary engineers should take measures to reduce the risk of explosion when design ing a granary. The John S. Metcalf Co. Ltd., of Montreal, have realized that though an initial explosion is often only a small affair, it may give rise to a second, and even to a third, each one increas ing in extent and violence. They have therefore in the construc tion of the Port of Montreal granary, concentrated on the pre vention or localization of the initial explosion. To this end they have segregated the granary into smaller units, thereby reducing the danger to a possible minimum, as will be seen later.
Fortunately, Great Britain has not suffered from any serious explosion, probably on account of the fact that about 75% of imported wheat is used, which has already passed through granaries in the countries where it has been grown, so that a goodly percent age of dust has already been eliminated. Another reason for this immunity from explosions is probably that the British granaries are smaller. In Great Britain there are climatic difficulties in the way of storing the native grain on a large scale. To preserve newly harvested grain in good condition it should be kept as far as possible from moisture and heat, because it has a tendency to sweat when brought into a warehouse, and in this condition will easily heat, such heating, if allowed to continue, impairing the quality of the grain. These difficulties have been largely overcome by frequently transferring it from one silo to another.
Modern granaries are all built on the same fundamental plan and the mechanical equipment for receiving and discharging grain is similar in all of them. For taking in rail-borne grain the mechanical handling equipment consists essentially of truck unloading devices, bucket elevators and band conveyors; while in addition to these both barge elevators and pneumatic grain handling plant are employed, principally for transferring grain from vessels to granaries. In most cases it is necessary to receive and distribute grain by both rail and waterways, and since the railway system is the more flexible, most of the important grana ries are located on the waterside, where large vessels may be berthed for the discharging and receiving of the grain, while the railway sidings on the land side connect the granaries with the chief lines in the district. The Montreal granaries, for instance, are connected with the lines which traverse the Canadian wheat belt—Manitoba, Saskatchewan and Alberta.
Granaries as a rule are enormously heavy and the soil on which they are constructed is in many cases alluvial, conse quently the question of foundations is at all times of the greatest importance.
Harbour Commissioners of Montreal Granary No. 3.— This granary is of concrete construction and it has a total capacity of 2,000,000 bushels ; it has been specially designed with the view of guarding against explosions. Each department of the plant is segregated to form an isolated unit. The receiving house, for instance, which is perhaps the dustiest section, and therefore the place where explosions would be most likely to occur, stands quite apart from the granary proper. The unloading of the grain cars on their arrival at the granary is accomplished by a dumping process in which the car is first lifted and simul taneously tilted forward, then rocked endwise. With this, the unloading of a 6o-ton car takes only seven minutes, and one such car dumper can unload from seven to ten 2,000-bushel cars per hour.
The granary itself is divided into two units, each having a storage capacity of one million bushels, and separated from the working house, which is located between them, by substantial concrete walls. The only apertures in these walls are small open ings for the belt conveyors to pass through, and those for the necessary iron doors. Moreover, the lowest floor of the working house is on a level with the floor above the silo cells, while the space between the working house and ground level (about 1 oof t.) is entirely open, allowing the elevator legs to pass through. In these circumstances, should an explosion occur in the receiving house it would spend itself locally, since the only connections between it and the working floors are the elevator legs which are in the vast open space between the working floors and the ground. The casings, of light steel sheets, are carried up to a considerable height in the open, so that an explosion would blow them out and escape before it reached the building above. An explosion on either of the working floors would be kept from spreading to the adjacent granaries by the concrete walls, which would, at the same time, protect the working house if an ex plosion occurred in either of the two granaries. As an additional precaution, every bucket elevator and every silo cell has a separate vent through the roof to the open. The numerous windows are all hinged from the top and swing outwards with the least pressure from the inside. Practically speaking, all avenues through which an explosion can spread are closed. The risk of explosion is further reduced by the provision of roller bearings on all the machines, for the true rolling motion reduces friction to a mini mum and prevents heating of the journals. Lubricating difficulties are likewise overcome, since roller bearings require very little lubricant and that only periodically. As a matter of fact there are over 53,000 Hyatt roller bearings in this plant, and the motors installed for the conveyors are of one-third less power than those formerly employed when bearings of solid type were used. More over, reduction of strain permits the use of lighter and less costly conveyor belts.
Since damp or dirty grain has occasionally to be stored, means have been provided for drying and cleaning it. These operations are carried out in a ferro-concrete annexe, 5 5f t. long by 15f t. wide. The drying plant is capable of evaporating from 4% to 5% of moisture from the grain at the rate of 600 bushels per hour. The cleaning machinery has a combined capacity of 3,60o bushels per hour.
The grain is delivered at the track shed in bulk wagons of 45 tons capacity, which are spotted by electric capstans and end tipped by four hydraulically operated tipplers, one of which works in connection with each of the four railway lines. The grain is tipped into four under-rail hoppers, each of a capacity of 4o tons. Beneath these hoppers are f our band conveyors to receive and deliver the grain to the four main elevators which deposit it at the top of the building, whence it is conveyed, via weighing ma chines, spouting and conveyors, into any silo in the working house or storage annexe. The capacity of this intake plant is i,000 tons per hour if the supply is uninterrupted. The contents of any of the silos can be transferred to the shipping silos adjoining by band conveyors and the five shipping elevators ; or alternatively, they may be delivered from the hoppers below the weighing machines in the cupola by means of spouts. A shipping conveyor in the working house, a conveyor affording a connection between this and the shipping conveyor in the inclined gantry, and quay con veyors in the gallery, the latter running parallel with the quay alongside which the ships are unloaded, provide loading facilities for water transport. Grain can likewise be taken from the silos in the annexe by means of tunnel conveyors. From the quay conveyors grain is delivered into the holds of vessels through loading-out shoots, which can be raised, lowered or telescoped, and which are so hinged that they can be swung through an angle of fully one hundred and eighty degrees. The shipping galleries as well as their supporting trestles are constructed of structural steel. These gantries are covered in with galvanized corrugated steel sheets and have cement floors. The loading-out capacity is the same as that of the intake plant; i.e., i,000 tons per hour. Grain can also be loaded, either loose or in sacks, into rail or road wagons in the track shed through special loading shoots, either from the working house or from the centre tower on the quay.
For the purpose of removing the dust from all points where grain is fed on to, or delivered from, conveyors and elevators, as well as from the various tunnels, two dust extracting systems and one dust removal system with incinerator and packing machine have been provided. The whole of the machinery is driven by electric motors, fitted with starters which can be operated from various points in the building. A thermometer system has been fitted, which enables the temperature of the grain at various depths in each of the silos to be indicated on a dial in the granary office.
General cargo, as well as grain, can be simultaneously discharged from ships in No. 9 dock. Grain is conveyed from the ships to the granary on belt conveyors in subways on both north and south quays. That below the north quay extends about 95of t. along the dock from the granary, so that two full cargoes of grain can be unloaded simultaneously. The south subway extends the full length of five berths and is about half-a-mile long. On this side of the dock grain can be taken from ships while general cargo is being discharged. The conveyors in these subways can be fed from numerous points along the quay. With the layout of these conveyors six separate streams of grain can be carried to the granary at the same time, and as each conveyor can handle 200 tons per hour, the plant has an hourly intake capacity of 1,200 tons. The subway conveyors feed cross conveyors in the basement of the granary, these, in turn, feeding the six receiving elevators. The grain is conveyed to the top of the cupola by these elevators and delivered into automatic weighing machines, whence it passes into a steel hopper below. From this the grain is led by an elaborate system of spouts to the distributing con veyors over the silos, or, as an alternative, to a conveyor on the floor above the bins, which in turn feeds to the sacking and ship ping bins on the west side.
The silos round the four sides of the building, 81 in number, are divided into upper and lower parts by a sloping cross division inserted at a sufficient height to afford delivery by gravity from the upper part to the sacking sheds, and from the lower for shipping the grain. Sacking sheds are provided on all four sides of the granary, and are so built that wheat may be sacked off from any number of points at the same time. Railway wagons can be brought in and loaded on three sides of the granary under the sacking shed floors. A very complete dust collecting system is provided, which includes exhausters from the garners above the weighers, while "sweep-ups" are provided on all floors. The installation is electrically driven throughout. (G. F. Z.)