Plant.
A set of tools, machinery, apparatus, and fixtures as used in a particular business,
e. g. the tools, benches, vises, lathes, planers, etc., of a machinist; the forge (including bellows), anvil, hammers, tongs, etc., of a blacksmith.
That which is necessary to the conduct of the mechanical business, whatever it may be. The more complete the assortment of tools, the better their quality; and the more numerous they are, the more valuable is the
plant.
The rolling stock of a railway.
The vats, tubs, stills, coolers, etc., of a brewery or distillery.
[
1733]
(Product 80 tons per 24 hours.)
[
1734]
According to a report recently published in
Germany, the working plant of Krupp's steel works at
Essen was, during the last year , 514 melting, annealing, and cementing furnaces, 169 forges, 249 welding, puddling, and reheating furnaces, 245 cokeovens, 120 miscellaneous ovens or kilns, 256
steam-engines (collectively of 8,377 horse-power), 340 lathes.
119 planingmachines, 65 shaping-machines, 144 boring-machines, 120 unclassed machines, and 90 grindstones.
There were also 56 steam-hammers, one of which weighs 30 tons.
The number of workmen employed were 7,100, and 70,000 tons of steel were turned out. The
Bessemer convertors, of which there are several at work, are not enumerated in this list.
Plate XLII.
illustrates the Bessemer works of the
North Chicago Rolling-Mill Company, from which those of other large American works do not essentially differ.
Fig. 1 is a ground plan of the converting-engine and boilerhouses, and of the 25-foot floor of the cupola building.
Fig. 2 is a ground plan and
Fig. 3 a plan of the 37-foot or cupola charging-floor.
Fig. 4 is a section at
A B,
Fig. 2, showing the cupolas and their ladles in elevation.
Fig 5 is a section at
E F,
Fig. 1, showing a side elevation of the cranes, convertors, cupolas, etc.
Fig 6 is an end elevation of the buildings.
The ground-floor of the works, contrary to the
English practice, is all on the same level, is accessible from all sides, and the engine and boiler houses are at the side of the converting building, leaving the ends open for the through passages
A B I J.
The hoist for coal, etc., and that for iron are at opposite ends of the cupola building, — an arrangement which allows more room in the yard than if they were placed side by side.
A hydraulic cylinder, whose stroke is equal to one half the distance traversed by the hoist, is most convenient and durable.
The
pig-iron and coal for the charges are carried on light fourwheeled iron wagons, easily managed by one man. These possess the advantage over those of larger size, of being less liable to interfere with each other upon the charging-ground, and also afford greater facilities for the intimate intermixture of the different qualities of pig-metal, of which six or more kinds are thoroughly mixed in each wagon before charging.
In this country, cupolas are used instead of reverberatory furnaces, and this practice is being introduced abroad.
The cupola is cheaper to construct and maintain, affords greater heat, melting the metal more rapidly, and melts 5 to 6 pounds of metal to the pound of coal.
It also occupies much less room and requires a less costly building than the reverberatory furnace.
In order to adapt the ordinary foundry cupola to the Bessemer process it was found necessary to increase the depth from the tuyeres to the tap from one foot to three or four feet, to double the sectional area of the tuyeres, and to reduce the projection of the boshes.
The dimensions of the cupolas are about as follows: hight, 14 feet; interior diameter of elliptical cupola, 6′ 5″ by 3′ 5″; the aggregate sectional area of the tuyeres, six in number, is 200 square inches.
Circular cupolas having the same sectional area are sometimes employed.
The charge consists, first, of 5, 400 pounds of coal, over which are placed from 3 to 3 3/4 tons of
pig-iron; this is succeeded by 1,400 pounds of coal, over which is charged the same amount of metal These alternate charges of coal and metal are continued until the cupola is filled, a small quantity of limestone being added as a flux.
The cupola is kept filled to the charging-door for from 8 to 10 hours It will hold 5 tons during the first few charges; but as the hearth becomes filled with slag, the capacity is decreased, and more frequent tapping is required.
They are capable of melting 100 tons of iron in 9 hours. The molten iron is tapped from the cupola into ladles
K, having a capacity of 12 tons each.
The objects of interposing ladles between the cupolas and convertors, instead of tapping directly into the latter, are, (1.) that the gray iron charges may be accurately weighed, so that the amount of spiegeleisen to be added may be definitely ascertained; (2.) the convenience of holding the metal until the vessels are ready to receive it. Pressureblowers have been usually employed for the cupolas, but of late the Sturtevant fan-blower has been successfully introduced at the Troy works.
The cupola dump
L,
Fig. 5, is situated conveniently to the cinder-mill,
Fig. 2, where the cinders are ground, so that the
shot-iron may be saved and remelted.
The cupola charging-floor is over the ladles, thus permitting the width of the building to be reduced.
The molten metal is conveyed from the cupolas to the convertors by means of the ladles
K and runners
M. These deposit it in a trough having branches by which it is conducted to either convertor.
The spiegeleisen furnaces are shown in plan
Fig. 1, and in cross section
Fig. 4.
Reverberatory furnaces are preferred for melting spiegeleisen, as the charges may be kept hot longer.
Cupolas are, however, used in some works.
The engine which drives the blower is placed beneath the charging-floor of the building, to economize space.
This engine also drives the cinder-mills.
At the opposite end of the converting building a space is left for grinding and mixing the refractory material for lining vessels, etc.
In the converting department of all American works the vessels are placed side by side and raised above the general level.
A platform extends around the convertors, by means of which all parts of the vessels are easily accessible.
A passage Q on the same level affords access to the coal-hoist.
This arrangement also allows greater swing to the cranes, the side ingotcranes
R and
S commanding the vessels, the pit, and all the floor room over which they swing.
The central ingot-crane
T commands the pit and a large floor space, and all the cranes swing over the railroad
I J. The ingots are removed by cars as fast as produced, and taken to the weighing-house at the end
J of the road.
The cupola building has bins for holding the materials, as coal, etc., required for current use. Where, as in
England, everything in the melting department is on different levels, the buildings are necessarily large, the distance between the bins and the places where their contents are to be used great, and the operations interfere with each other, whereas in a high building with several floors the operations are simplified and the materials more conveniently stored.
Thorough ventilation is secured by lantern roofs and windows on every side.
The hight of the cupola building allowing free ventilation on all sides, is an important feature.
The gangway
A B,
Fig. 2, is convenient for ventilation, also for reaching all sides of the vessels, as well as for transportation.
Underneath this, in the newer works, is an underground passage (
Fig. 5) which communicates with the cellar under the grinding-mill and the coal-hoist.
This serves for removing waste material.
The water and blast pipes leading from the regulator are secured to the walls of this passage; an indispensable precaution in a cold climate.
Until recently, only eight heats per day could be made with the five-ton convertors, owing to the difficulty of replacing the bottoms of the converting vessels when the tuyeres were worn too short.
This difficulty has been overcome by
Mr. Alexander L. Holley, the consulting engineer of the principal
Bessemer steel works of the
United States.
Since
Mr. Holley's improvements but two or three hours time is required to replace a bottom.
This has doubled the production, from 16 to 25 five-ton heats now being made in a day of 24 hours. The quantity of metal usually charged into the convertor at each heat is from 12,000 to 12,500 pounds, to which from 5 to 8 per cent of spiegeleisen is added at the close of the operation.
The steel is cast into ingots which are afterward rolled into blooms.
In a few American works, however, they are hammered into blooms.
See Bessemer process; convertor.
