T H E JOURNAL OF I N D U S T R I A L A N D ENGINEERING CHEMISTRY
640
Vol. 13, No. 7
A Rotary Digester for Use in Bagasse Analysis' By Guilford L. Spencer THECUBAN-AMERICAN SUGAR COMPANY, N E W YORK, N. Y.
The determination of sugar in cane bagasse, with the customary digesters, usually presents difficulties through the need of keeping the material in motion while treating it with hot water. Motion is necessary to promote maceration a n d diffusion. Following the digestion, the extract must be cooled and, without special arrangement, this is a slow process. Further, many bagasse tests must be made daily in full control of cane milling. To permit attention to other duties, the chemist must be relieved of as much of the immediate supervision of the bagasse tests as is possible. To facilitate this testing, the author has devised a rotary digester, which is simply a steam bath in which cylinders, containing the sample and water, are rotated. The apparatus is fitted for three simultaneous tests. The casing of the digester is cylindrical and of 24-in. internal diameter. A triangular hub, 4 in. long, turns freely with a shaft, which is fitted with an adjustable cone bearing inside the digester casing at one end, while the other end projects through a bronze bearing and carries a pulley 18 in. in diameter. The pulley is grooved for a sewing machine belt or a light chain. Clamps are provided on the hub for attaching three aluminium cylinders, 4 in. in diameter by 8 in. long, for samples. The clamps also hold the covers of the cylinders in position. The covers have break-vacuum cocks. The pulley is connected through a laboratory reducing gear, 48: 1, with a small electric motor, and is rotated a t about 5 r. p. m. The cylinders
are revolved endwise. A hinged cover closes the apparatus when in use. The casing is drained by a 1-in. pipe, provided with a stop valve. A 1-in. overflow pipe leads from a point below the shaft and connects with the drain below the stop valve. The apparatus is provided with a 0.125-in. steam pipe and a 0.5-in. cold water pipe. The following is the procedure in making a sugar test with this digester: 100 g. of chopped bagasse are weighed in a tared cylinder; 1liter of very hot water is added; the cover, with the cock closed, is placed in position on the cylinder and this is then locked on the hub. If ammonia is used in preserving the material while collecting the sample, no alkali is added to the digestion water; otherwise sodium carbonate is added. The cover is closed,and withthe bottom drain open steam is turned into the casing. Very little steam is needed. With the outlet to the drain open, the pressure is that of the atmosphere. The cylinders are revolved for an hour in the steam and this is then shut off, and the drain is closed; cold water is now admitted and the revolution of the hub is continued until the sample is cooled. The drain is opened, and the cylinder is removed, dried, and weighed. Further procedure is as in the customary methods of analysis. As may be noted, the slow motion of the hub causes the bagasse to fall from end to end of the cylinder, agitates the extract, and promotes maceration and diffusion.
Continuous Sampling of Sugar Liquors' By Walter L. Jordan 83 WASHINGTON PLACE, NEWYORK,N. Y.
Sampling of sugar juices and liquors is of first importance in mill and refinery control. Exact analytical work in the laboratory will have little value if the samples do not truly represent the products that are going through the mill or factory. Usually samples are taken periodically. The men a t the various stations are given bottles to be filled at intervals of 1 or 2 hrs. The sample is dependent upon the sampler, and he soon learns to take samples that show his own work to be satisfactory, instead of those that will correctly reflect
Methods now used for sampling liquids automatically, as far as the writer is aware, all give a sample the volume of which is dependent upon the time element and bears no relation to variations in flow of the liquid sampled. Thus if a drip sample is taken, a small flow through the main pipe line adds just as much to the sample as a large flow, If
FIG.3
FIG. 1
FIG.2
manufacturing conditions and assist in the process control. 1 Presented before the Section of Sugar Chemistry and Technology a t the 61st Meeting of the American Chemical Society, Rochester, N. Y., April 26 to 29, 1921.
a t the same time the composition of the juice varies, it is evident that such a sample cannot be representative of the total juice flowing. A sample proportional to the total flow may be obtained by the circular weir shown in Fig. 1. The sample is that portion overflowing through the vertical slot. This device can be applied wherever the liquor to be sampled flows into a receiving tank, measuring tank, defecator, etc. Instead of the juice or liquor running into the tank through a downward turned nipple or fitting, this is turned up so that the pipe fills and the juice spills over the level edge of the
