Drying.—Wool which is intended to be dyed passes from the scouring to the dye bath. When this is not the case, it is dried.
The process of drying, ss usually performed, is in several respects unsatisfactory. Ordinarily it is spread upon a perforated iron floor over the boilers, when that can be arranged, in order to econo mize what would otherwise be wasted heat. When this is not convenient, steam-pipes are arranged so as to admit of the wool being laid over them. Layers of wool are then spread over the area in succession, and the wool is dried by exposure in this manner to the radiant heat. It is obvious, how ever, that when the layer is unevenly spread, which eannot be avoided, the drying will be uneven, and injury to the wool will result. The parts in contact with the floor will dry first, and, if not very carefully tended, will become hard and brittle before the other or upper portion of the layer has been sufficiently dried. The manner in which this is sought to be obviated is by turning the wool frequently and respreading the layer. If carefully done, this prevents much injury accruing, though the evil is not entirely eliminated.
This process, unpromising as it might appear, has also been subordinated to mechanical treat ment, and Fig. 1443 represents one of the machines employed for this purpose. As will be seen, it consists of an oblong iron frame a, with sloping sides and a flat top. A light iron frame, over which is stretched a covering of strong galvanized iron network b, forms the roof. Above this project a number of tubes c, forming air-inlets, which are arranged at equal distances from each other in two rows. Two shafts d d' extend horizontally through the length of the frame, having bearings or journals of Special construction, which are self-lubricating. These journals are placed immediately 1443.
above each air-inlet. On each shaft, is a series of fans, composed of wrought-iron, and having similar casings or bottonrs. These fans draw the air in thmugh the inlets c. Inside, are a number of steam-pipes, made of either wrought or cast iron, 2-3 in. internal diameter. The fan-shafts carry fast and loose pulleys e for driving.
The process is ea follows :—The net-work being covered with a uniform layer of wool, not very thick, the steam is turned into the pipes, and the fans &reset to work. _These draw the air through the inlets ; in its course it comes into contact with the steam-heated pipes, by which it is warmed, and then uniforraly discharged through the net-work and the layer of wool. As the heat eau be regulated to a nicety, or even cold air be employed, the wool with care never need be overdried or rendered harsh. This machine is slim made by McNaught. Its dimensions are 6-9 yd. by 3 yd. It is capable of drying 2000-3000 lb. in a day of 10 hours.
The objections to the antiquated system of drying described above, have also led to the inven tion of another drying-machine, a longitudinal section of which is shown in Fig. 1444. This differs
essentially from the one just described. It is the invention of Moore, of Trowbridge, the centre of the West of England clothing district, and is made by W. Whiteley and Sons, Lockwood, near Huddersfield. Hot air is the agent employed in drying, as in the preceding machine, but provision is made for continually redistributing the wool. The moving parts, omitting cognizance of the driving-gear, consist of two series of rollers a a', and a drum b shout 4 ft. diam., the periphery of which is covered with small spikes. When working, this drum makes 100-120 rev. a minute. The two series of rollers also revolve, though only at a slow pace, their function being to carry the wool backwards and forwards. As the rollers of each series all revolve in one direction. it is obvious that the wool will be passed from one to another until the end is attained. The rollers are made of iron tubes of about in. diam., and are set sufficiently far apart to allow of free revolution, the interspaces permitting the circulation of the current of heated air. The revolution speeds of these rollers can be regulated according to requirement. Beneath the rollers, are several tiers of steam-pipes c', for the purpose of heating the air. At the 'top of the machine, are two flues or tubes d d', whose extremities are carried outside the building, and are supplied with power-driven exhaust fans, for the purpose of inducing a current through the machine. Each end of the machine is furnished with a door. When the process commences, the door e over the spiked drum is closed and fastened, and the one at the opposite end f is opened for the reception of the charge of wool. The weight usually put in at one time is sufficient to yield about 100 lb. of dry wool. This quantity is placed upon the lower series ef rollers, and the door is then closed. By the action of the rollers, the wool is gradually carried forward, until it comes within reach of the spikes of the.revolving cylinder, which strike it downward, carry it round, and project it upon the upper series of rollers. Here it commences its return course, and when arrived at the last roller, it falls over, dropping down upon the lower series again, when it recommences aud repeats its journey. This is continued for 20-30 minutes, when the °barge will be thoroughly dried, and ready for withdrawing. The door being opened, the spiked drum throws out the wool. g, as shown in the illustration. The heap h represents wet wool. The tmveraing of the wool by the rollers, and its teazing by the spiked cylinder, se,cures thoroughly uniform drying, whilst the action of the latter also often renders it unnecessary to pass the wool through a teazer before sending it to the card. To facilitate the extraction of dust, dirt, aud foreign matter, a grid is inserted in the under portion of the case. About 1500-2000 lb. of wool may be dried upon the machine represented. It is made in various sizes, according to requirement.