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matically supply it to the furnace as required. The ashes from each boiler are taken by a screw conveyer underneath the floor to another elevator, which delivers them into an overhead ash bin, from which they are discharged into carts for removal. Thus, from the time the coal is dumped by the teamster until the ashes are discharged into the carts there is practically no manual labor required to handle coal or ashes.
In addition to the saving in labor, so perfectly does the mechanical stoker supply the proper amount of fuel and oxygen that absolutoly no smoke is produced; not by burning it, but preventing it by perfect combustion of the gases which are usually allowed to escape up the chimney, a source of loss to the manufacturer and a nuisance to his neighbors. The perfect combustion of the fuel is also shown by the fact that the ashes from a ton of coal are but a little over one half those produced from the same quantity of coal under hand-fired boilers at the same manufactory.
The hot waste gases from the boilers pass through an economizer, thereby utilizing the heat they contain to heat the feed water.
The necessary draft for the boilers is produced by a large, slow-running exhaust fan, discharging into a short iron stack placed immediately above it, and extending through the roof about twenty-five feet. The fan is driven by a small Westinghouse engine, having a pressure regulator attached to the steam pipe, for controlling the speed of engine and fan, so that they will run slow or fast, according as the steam pressure at the boiler varies. This fan, with its trenty-five-foot stack, is capable of producing a ilraft pressure equal to that of a tro-hundreilfoot chimney costing ten times as much to build, and is far more flexible in meeting sudden demands for steam.
The economy in labor and fuel obtainable from a plant of boilers thus equipped with stokers, economizers, coal and ash machinery and mechanical draft, will not only pay a handsome dividend on the investment, but will also greatly lengthen the life of the boilers, and reduce the possibility of accidents
due to the severe strains caused by the irregularity of handfiring.
We were also shown a sectional-perspective view of the immense boiler house and steam plant at the Spreckel Sugar Refinery, Philadelphia (see folder). This plant consists of eight thousand horse-power Babcock and Wilcox boilers, placed in two batteries of four thousand horse-power each, one above the other, with the coal-storage bunker occupying the third story of the building. This entire battery of boilers is equipped with sixty Roney mechanical stokers, to which the coal is supplied by chutes from the storage overhead as fast as required. The coal is delivered by train load to the boiler house, and dumped into hoppers which supply two large coal crushers placed underneath the railroad track. The coal when broken to a uniform size is delivered by means of spiral conveyers to vertical bucket elevators, which deliver the coal into a horizontal conveyer, which distributes the coal the entire length of the coal bunker above the boilers. The ashes are also discharged by gravity through chutes to a conveyer placed in the cellar, which in turn discharges them into an elevator, from which they are delivered into an elevated ash bin, from which they flow by gravity into cars for removal; so that from the time the bottom of the coal cars are dumped there is no further handling of coal or ashes until they are delivered into cars for removal. So perfectly does the entire system work that one man with ease attends to two thousand horse-power boilers.
Mr. BARKER. Mr. HowATSON raised one question, which was, why the Americans use the multitubular type of boiler, while the Englishmen use the Lancashire type. I know of no one who is so well fitted to answer that question as M TOMAS J. BORDEN, and I should like to hear from him. Mr. BORDEN. I suppose that Americans us
ental tubular boilers extensively because the cost
tioi and repairs, for equal steam capacity, i
of internally fired boilers of the English Galloway,” which is the chief repro
his: thus far in this country.
When using bituminous coal there is an advantage in the passage of the flame the full length of the boiler before entering the return tubes, thereby promoting complete combustion with a minimum discharge of smoke from the stack. With horizontal tubular boilers properly set and fired, bituminous coal can be used with almost no smoke. There are some internally fired boilers at the sewage pumping station at South Boston, which yield good results as to economy of fuel, but their cost was much greater than an equal capacity of horizontal tubular boilers.
Mr. JOHNSTON. I will state why I adopted the multitubular boiler. Many years ago we put in some hog-nosed boilers ; we ran them six years, not economically, and then, in rearranging our steam plant, we discarded these and put in boilers with the internal fire arrangement, and after running them for seven years we discarded those and put in the multitubular boiler. The hog-nose was a long thirty-two-foot tubular boiler, with the fire underneath, with a consumption of four, we will say; the internal fire boiler, six feet in diameter and eighteen feet long, we will say has a consumption of six; the multitubular boiler, with the fire underneath, has a consumption of ten, four, six and ten. What is the reason we do not get a better result from the internal fire boiler? The fire box is inside the boiler, and there are four inches of water space around the ash box. The air and feed of the boiler passing over the whole surface of the ash box, the water is chilled; and you lose all the gain there is from having a fire inside the boiler.
Mr. ATKINSON referred to one fact, that when we got the improvements made we would have slow combustion, and we would therefore have great economy; I mean complete combustion.
Mr. JOHNSTON. I made a test of slow combustion, ten years ago, with a one hundred horse-power tubular boiler, fire under
, neath. With slow combustion, lowering the draught, the evaporation was 6.5; I increased the draught and the consumption of fuel for the boiler forty per cent., and the evaporation was 10.5 instead of 6.5.
Mr. BIRKENHEAD. With soft coal how many feet from the furnace can you get a temperature of 212° ?
Mr. HOWATSON. With our apparatus by which the smoke is prevented entirely, the gases going away from the fire at a higher temperature than the fire, we find back of the boiler a temperature of 212°. The heat is led round, the boiler on one side and brought back again, and is taken up by the shell of the boiler.
Mr. BIRKENHEAD. It would interest me, and I have no doubt the rest of the members, if some figures could be given as to the distance that heat will travel under or through a boiler from a furnace of anthracite coal compared with Cumberland coal, and also with a wood fire. I have noticed that hard coal, on account, perhaps, of its not carrying a flame, very soon loses its boiling temperature of 212°. If I am correct, is it not important that boilers should be constructed with this point in view, since in the case of a return-flue boiler the distance may be so great that the heat of the furnace may become in a measure absorbed before it has reached the chimney? If it should do so, would it not take away a portion of the heat it has just given?
Mr. BORDEN. The temperature directly under a horizontal tubular boiler, using either anthracite or bituminous coal, with boiler worked fairly up to its capacity, is rarely less than 700 to 800 degrees, and may be much more than 1,000 degrees. If carrying steam at 80 pounds' pressure, the temperature of which is about 324 degrees, exceedingly good results will be obtained if the temperature of the gases, after passing through the tubes, on discharge into the chimney, does not exceed 375 degrees. They are usually 400 to 500 degrees. Hence Mr. BIRKENHEAD's enquiry as to the effect of a temperature of less than 212 degrees is not pertinent. Heat once generated will travel under or through a boiler of a given type equal distan, with equal diminution of temperature, whatever coal i The loss, by absorption of the foundations, or radi: surfaces exposed to the air, is no greater with anthr
with bituminous coal; but the distance the flame is permitted to travel before entering small tubes has much more effect upon the complete combustion of bituminous coal than upon anthracite. Hence the horizontal return tubular boiler admits of more thorough combustion of bituminous coal, and consequently less smoke, than most types of internally fired boilers.
A single horizontal tubular boiler presents a considerable external area of brick-work as a radiating surface; but several such boilers set together, as is usual in large steam plants, with the top of the setting well protected by a good non-conductor, lose comparatively little heat. In the use of anthracite coal very good results can be obtained from internally fired upright tubular boilers of the “Manning” or “ Corliss” types, which also cost materially less than the “Galloway” boilers, and I think yield equally good results, if properly proportioned to the work expected of them. These boilers, however, have the lower tube sheet in too close proximity to the grates to admit of complete combustion of bituminous coal, the tendency being to smother the flame on its entrance to the tubes, and therefore to discharge more or less smoke, especially when fires are forced.
Mr. BIRKENHEAD. It seems to me the boiler should be adapted to the coal or the coal to the boiler.
The PRESIDENT. We should be pleased to hear from Mr.
Mr. VICARS. I have nothing to add to what my colleague has said. I thank you very much for your kind reception, and I hope when you come to England you will come to see us. We would like to return to you in some way what you have given to us to-day. I hope this mechanical stoker of ours will be taken up by you before the expiration of the period which Mr. ATKINSON allows for his theories to materialize. Ten years is a long time to wait.