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Scientific American Supplement, No. 446, July 19, 1884试读：
SCIENTIFIC AMERICAN SUPPLEMENT NO.446
IMPROVED FILTER PRESSES.
Hitherto it has been found that of all the appliances and methods for separating the liquid from the solid matters, whether it is in the case of effluents from tanneries and other manufactories, or the ocherous and muddy sludges taken from the settling tanks in mines, some of which contain from 90 to 95 per cent．of water, the filter press is the best and the most economical, and it is to this particular process that Messrs．Johnson's exhibits at the Health Exhibition, London, chiefly relate．Our engravings are from The Engineer．A filter press consists of a number of narrow cells of cast iron, shown in Figs.3 and 4, held together in a suitable frame, the interior frames being provided with drainage surfaces communicating with outlets at the bottom, and covered with a filtering medium, which is generally cloth or paper．The interior of the cells so built up are in direct communication with each other, or with a common channel for the introduction of the matter to be filtered, and as the only exit is through the cloth or paper, the solid portion is kept back while the liquid passes through and escapes by the drainage surfaces to the outlets．The cells are subjected to pressure, which increases as the operation goes on, from the growing resistance offered by the increasing deposit of solid matter on the cloths; and it is therefore necessary that they should be provided with a jointing strip around the outside, and be pressed together sufficiently to prevent any escape of liquid．In ordinary working both sides of the cell are exposed to the same pressure, but in some cases the feed passages become choked, and destroy the equilibrium．This, in the earlier machines, gave rise to considerable annoyance, as the diaphragms, being thin, readily collapsed at even moderate pressures; but recently all trouble on this head has been obviated by introducing the three projections near the center, as shown in the cuts, which bear upon each other and form a series of stays from one end of the cells to the other, supporting the plates until the obstruction is forced away．We give an illustration below showing the arrangement of a pair of filter presses with pneumatic pressure apparatus, which has been successfully applied for dealing with sludge containing a large amount of fibrous matter and rubbish, which could not be conveniently treated with by pumps in the ordinary way．The sludge is allowed to gravitate into wrought iron receivers placed below the floor, and of sufficient size to receive one charge．From these vessels it is forced into the presses by means of air compressed to from 100 lb．to 120 lb．per square inch, the air being supplied by the horizontal pump shown in the engraving．The press is thus almost instantaneously filled, and the whole operation is completed in about an hour, the result being a hard pressed cake containing about 45 per cent．of water, which can be easily handled and disposed of as required．The same arrangement is in use for dealing with sewage sludge, and the advantages of the compressed air system over the ordinary pumps, as well as the ready and cleanly method of separating the liquid, will probably commend itself to many of our readers．We understand that from careful experiments on a large scale, extending over a period of two years, the cost of filtration, including all expenses, has been found to be not more than about 6d．per ton of wet sludge．A number of specimens of waste liquors from factories with the residual matters pressed into cakes, and also of the purified effluents, are exhibited．These will prove of interest to many, all the more so since in some instances the waste products are converted into materials of value, which, it is stated, will more than repay for the outlay incurred.Fig.3．Fig 4.
Another application of the filter press is in the Porter-Clark process of softening water, which is shown in operation．We may briefly state that the chief object is to precipitate the bicarbonates of lime and magnesia held in solution by the water, and so get rid of what is known as the temporary hardness．To accomplish this, strong lime water is introduced in a clear state to the water to be softened, the quantity being regulated according to the amount of bicarbonates in solution．The immediate effect of this is that a proportion of the carbonic acid of the latter combines with the invisible lime of the clear lime water, forming a chalky precipitate, while the loss of this proportion of carbonic acid also reduces the invisible bicarbonates into visible carbonates．The precipitates thus formed are in the state of an impalpable powder, and in the original Clark process many hours were required for their subsidence in large settling tanks, which had to be in duplicate in order to permit of continuous working．By Mr．Porter's process, however, this is obviated by the use of filter presses, through which the chalky water is passed, the precipitate being left behind, while, by means of a special arrangement of cells, the softened and purified water is discharged under pressure to the service tanks．Large quantities can thus be dealt with, within small space, and in many cases no pumping is required, as the resistance of the filtering medium being small, the ordinary pressure in the main is but little reduced．One of the apparatus exhibited is designed for use in private mansions, and will soften and filter 750 gallons a day．In such a case, where it would probably be inconvenient to apply the usual agitating machinery, special arrangements have been made by which all the milk of lime for a day's working is made at one time in a special vessel agitated by hand, on the evening previous to the day on which it is to be used．Time is thus given for the particles of lime to settle during the night．The clear lime water is introduced into the mixing vessel by means of a charge of air compressed in the top of a receiver, by the action of water from the main, the air being admitted to the milk of lime vessel through a suitable regulating valve．A very small filter suffices for removing the precipitate, and the clear, softened water can either be used at once, or stored in the usual way．The advantages which would accrue to the community at large from the general adoption of some cheap method of reducing the hardness of water are too well known to need much comment from us.
PNEUMATIC MALTING.
According to K．Lintner, the worst features of the present system of malting are the inequalities of water and temperature in the heaps and the irregular supplies of oxygen to, and removal of carbonic acid from, the germinating grain．The importance of the last two points is demonstrated by the facts that, when oxygen is cut off, alcoholic fermentation——giving rise to the well-known odor of apples——sets in in the cells, and that in an atmosphere with 20 per cent．of carbonic acid, germination ceases．The open pneumatic system, which consists in drawing warm air through the heaps spread on a perforated floor, should yield better results．All the processes are thoroughly controlled by the eye and by the thermometer, great cleanliness is possible, and the space requisite is only one-third of that required on the old plan．Since May, 1882, this method has been successfully worked at Puntigam, where plant has been established sufficient for an annual output of 7,000 qrs．of malt．The closed pneumatic system labors under the disadvantages that from the form of the apparatus germination cannot be thoroughly controlled, and cleanliness is very difficult to maintain, while the supply of oxygen is, as a rule, more irregular than with the open floors.IMPROVED PNEUMATIC FILTERING PRESSES.
A NEW FORM OF GAS WASHER.
By A．BANDSEPT, of Brussels.
The washer is an appliance intended to condense and clean gas, which, on leaving the hydraulic main, holds in suspension a great many properties that are injurious to its illuminating power, and cannot, if retained, be turned to profitable account．This cleaning process is not difficult to carry out effectually; and most of the appliances invented for the purpose would be highly efficacious if they did not in other respects present certain very serious inconveniences．The passage of the gas through a column of cold water is, of course, sufficient to condense it, and clear it of these injurious properties; but this operation has for its immediate effect the presentation of an obstacle to the flow of the gas, and consequently augmentation of pressure in the retorts．In order to obviate this inconvenience (which exists notwithstanding the use of the best washers), exhausters are employed to draw the gas from the retorts and force it into the washers．There is, however, another inconvenience which can only be remedied by the use of a second exhauster, viz., the loss of pressure after the passage of the gas through the washer——a loss resulting from the obstacle presented by this appliance to the steady flow of the gas．Now as, in the course of its passage through the remaining apparatus, on its way to the holder, the gas will have to suffer a considerable loss of pressure, it is of the greatest importance that the washer should deprive it of as little as possible．It will be obvious, therefore, that a washer which fulfills the best conditions as far as regards the cleaning of the gas will be absolutely perfect if it does not present any impediment to its flow．Such an appliance is that which is shown in the illustration on next page．Its object is, while allowing for the washing being as vigorous and as long-continued as may be desired, to draw the gas out of the retorts, and, having cleansed it perfectly from its deleterious properties, to force it onward．The apparatus consequently supplies the place of the exhauster and the scrubber.
The new washer consists of a rectangular box of cast iron, having a half-cylindrical cover, in the upper part of which is fixed a pipe to carry off the gas．In the box there is placed horizontally a turbine, the hollow axis of which serves for the conveyance of the gas into the vessel．For this purpose the axis is perforated with a number of small holes, some of which are tapped, so as to allow of there being screwed on to the axis, and perpendicularly thereto, a series of brooms made of dog grass, and having their handles threaded for the purpose．These brooms are arranged in such a way as not to encounter too great resistance from contact with the water contained in the vessel, and so that the water cast up by them shall not be all thrown in the same direction．To obviate these inconveniences they are fixed obliquely to the axis of the central pipe, and are differently arranged in regard to each other．A more symmetrical disposition of them could, however, be adopted by placing them zigzag, or in such a way as to form two helices, one of which would move in a particular direction, and the other in a different way．The central pipe, furnished with its brooms, being set in motion by means of a pulley fixed upon its axis (which also carries a flywheel), the gas, drawn in at the center, and escaping by the holes made in the pipe, is forced to the circumference of the vessel, where it passes out.
The effect of this washer is first, to break up the current of gas, and then force it violently into the water; at the same time sending into it the spray of water thrown up by the brooms．This double operation is constantly going on, so that the gas, having been saturated by the transfusion into it of a vigorous shower of water (into the bulk of which it is subsequently immersed), is forced, on leaving the water, to again undergo similar treatment．The same quantity of gas is therefore several times submitted to the washing process, till at length it finds its way to the outlet, and makes its escape．The extent to which the washing of the gas is carried is, consequently, only limited by the speed of the apparatus, or rather by the ratio of the speed to the initial pressure of the gas．This limit being determined, the operation may be continued indefinitely, by making the gas pass into several washers in succession．There is, therefore, no reason why the gas should not, after undergoing this treatment, be absolutely freed of all those properties which are susceptible of removal by water．In fact, all that is requisite is to increase the dimensions of the vessel, so as to compel the gas to remain longer therein, and thus cause it to undergo more frequently the operation of washing．These dimensions being fixed within reasonable limits, if the gas is not sufficiently washed, the speed of the apparatus may be increased; and the degree of washing will be thereby augmented．If this does not suffice, the number of turbines may be increased, and the gas passed from one to the other until the gas is perfectly clean．This series of operations would, however, with any kind of washer, result in thoroughly cleansing the gas．The only thing that makes such a process practically impossible is the very considerable or it may be even total loss of pressure which it entails．By the new system, the loss of pressure is nil, inasmuch as each turbine becomes in reality an exhauster．The gas, entering the washer at the axis, is drawn to the circumference by the rotatory motion of the brooms, which thus form a ventilator．It follows, therefore, that on leaving the vessel the gas will have a greater pressure than it had on entering it; and this increase of pressure may be augmented to any desired extent by altering the speed of rotation of the axis, precisely as in the case of an exhauster.
Forcing the gas violently into water, and at the same time dividing the current, is evidently the most simple, rational, and efficient method of washing, especially when this operation is effected by brooms fixed on a shaft and rotated with great speed．Therefore, if there had not been this loss of pressure to deal with——a fatal consequence of every violent operation——the question of perfect washing would probably have been solved long ago．The invention which I have now submitted consists of an arrangement which enables all loss of pressure to be avoided, inasmuch as it furnishes the apparatus with the greatest number of valuable qualities, whether regarded from the point of view of washing or that of condensation.Longitudinal Section．Elevation．Transverse Section.
Referring to the illustration, the gas enters the washer by the pipe, A, which terminates in the form of a [Symbol: inverted T]．One end (a) of this pipe is bolted to the center of one of the sides of the cylindrical portion of the case, in which there is a hole of similar diameter to the pipe; the other (a') being formed by the face-plate of a stuffing-box, B, through which passes the central shaft, C, supported by the plummer-block, D, as shown．This shaft has upon its opposite end a plate perforated with holes, E, which is fixed upon the flange of a horizontal pipe, F．This pipe is closed at the other end by means of a plate, E', furnished with a spindle, supported by a stuffing-box, B', and carrying a fly-wheel, G．The central pipe, F, is perforated with a number of small holes．The gas entering by the pipe, A, makes its way into the central pipe through the openings in the plate, E, and passes into the cylindrical case through the small holes in the central pipe, which carries the brooms, H．These are caused to rotate rapidly by means of the pulley, I; and thus a constant shower of water is projected into the cylindrical case．When the gas has been several times subjected to the washing process, it passes off by the pipe, K．Fresh cold water is supplied to the vessel by the pipe, L; and M is the outlet for the tar.——Journal of Gas Lighting.
THE WIND MILL.
[Footnote: A paper read before the Engineers' Club of St．Louis, 1884.]
By JAMES W．HILL.
In the history of the world the utilization of the wind as a motive power antedates the use of both water and steam for the same purpose.
The advent of steam caused a cessation in the progress of wind power, and it was comparatively neglected for many years．But more recently attention has been again drawn to it, with the result of developing improvements, so that it is now utilized in many ways.
The need in the West of a motive power where water power is rare and fuel expensive has done much to develop and perfect wind mills.
Wind mills, as at present constructed in this country, are of recent date.
The mill known as the "Eclipse" was the first mill of its class built．It is known as the "solid-wheel, self-regulating pattern," and was invented about seventeen years ago．The wind wheel is of the rosette type, built without any joints, which gives it the name "solid wheel," in contradistinction to wheels made with loose sections or fans hinged to the arms or spokes, and known as "section wheel mills."
The regulation of the Eclipse mill is accomplished by the use of a small adjustable side vane, flexible or hinged rudder vane, and weighted lever, as shown in Plate 1 (on the larger sizes of mills iron balls attached to a chain are used in place of the weighted lever)．The side vane and weight on lever being adjustable, can be set to run the mill at any desired speed.
Now you will observe from the model that the action of the governing mechanism is automatic．As the velocity of the wind increases, the pressure on the side vane tends to carry the wind wheel around edgewise to the wind and parallel to the rudder vane, thereby changing the angle and reducing the area exposed to the wind; at the same time the lever, with adjustable weight attached, swings from a vertical toward a horizontal position, the resistance increasing as it moves toward the latter position．This acts as a counterbalance of varying resistance against the pressure of the wind on the side vane, and holds the mill at an angle to the plane of the wind, insuring thereby the number of revolutions per minute required, according to the position to which the governing mechanism has been set or adjusted.
If the velocity of the wind is such that the pressure on the side vane overcomes the resistance of the counter weight, then the side vane is carried around parallel with the rudder vane, presenting only the edge of the wind wheel or ends of the fans to the wind, when the mill stops running.
This type of mill presents more effective wind receiving or working surface when in the wind, and less surface exposed to storms when out of the wind, than any other type of mill．It is at all times under the control of an operator on the ground.
A 22-foot Eclipse mill presents 352 square feet of wind receiving and working surface in the wind, and only 9½ square feet of wind resisting surface when out of the wind.
Solid-wheel mills are superseding all others in this country, and are being exported largely to all parts of the world, in sizes from 10 to 30 feet in diameter．Many of these mills have withstood storms without injury, where substantial buildings in the immediate vicinity have been badly damaged．I will refer to some results accomplished with pumping mills:
In the spring of 1881 there was erected for Arkansas City, Kansas, a 14-foot diameter pumping wind mill; a 32,000-gallon water tank, resting on a stone substructure 15 feet high, the ground on which it stands being 4 feet higher than the main street of the town．One thousand four hundred feet of 4-inch wood pipe was used for mains, with 1,200 feet of 1½-inch wrought iron pipe．Three 3-inch fire hydrants were placed on the main street．The wind mill was located 1,100 feet from the tank, and forced the water this distance, elevating it 50 feet．We estimate that this mill is pumping from 18,000 to 20,000 gallons of water every twenty-four hours．We learned that these works have saved two buildings from burning, and that the water is being used for sprinkling the streets, and being furnished to consumers at the following rates per annum: Private houses, $5; stores, $5; hotels, $10; livery stables, $15．At these very low rates, the city has an income of $300 per annum．The approximate cost of the works was $2,000．This gives 15 per cent．interest on the investment, not deducting anything for repairs or maintenance, which has not cost $5 per annum so far.
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