US1272880A - Manufacture of bleaching-powder. - Google Patents

Description

l. W. MOORE.

MANUFACTUEE 0F BLEACHING POWDER.

APPLNIAIIH FILED FEB. 5. |918.

Patented .my 16,

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JOSEPH WILLIAM'. MGORE, OF RUNCORN, ENGLAND, ASSIGNOE, T0 CTN'EEfKELLEEE,

ALKALI COMPANY, LIMITED, OF LOEDON, ENGTAND.

Mai'rurricrunn or spaarzame-servons.

Speciication of Letters Patent.

Application filed February 5, 1918. Serial No.. 215,528.

e To all whom it may concern:

- Be it known that I, JOSEPH WILLIAM MOORE, a subject of the King of Great Britain, residing in Ituncorn, England,have

invented certain new and useful Improvements in the Manufacture of Bleaching- Powder, of which the following is a speciication.`

In the .manufacture of bleaching powder, by causing lime and chlorin to pass through a rotating tube, or series'of connected rotating tubes, it is of very considerable commercial and technical importance to obtain the gas issuing 'from the tube, free or almost free, from unabsorbed chlorin, while the bleach is being continuously produced.

Over forty years 'ago (see Hendersons British specication'No. 3080 of 1871) it was proposed to charge linie with chlorin by passing chlorin up inclined tubes or -cylin-f ders .about 40 feet long, through which lime was made toY travel by imparting rotation to the tubes or cylinders, or to screws inside them. The latter principle is embodied in the now well known apparatus, patented by Hasenclever in 1888, British specification No. 17012, but the rotating tube method, has so far as we know, hitherto, never been successfully attempted on the commercial scale.

Lunge in Sulphurc Acid and Alkali, vol.

I111, page 468 (1896 edition) says:

All mechanical bleaching' powder chainbers (other than Hasenclevers) hitherto erected have been abandoned after a short period of work, either because the machinery failed, or because the bleach came out Weak or both.

Among the drawbacks to the before-inentioned proposals are that the shafts and cylinders rapidly corrode and the corrosion products mix with the powder decomposing same to some extent, impairing its keeping qualities and injuring its color, and where Scrapers or feeders are employed the powder is compressed against the cylinder wall forming an extremely hard and trouble-- to be vperiodically` some crust which has chipped oil' involving much disagreeable and expensive work. In addition to these drawbacks the gas issuing from such a rotating tube as described by Henderson contains a very considerable proportion of unabsorbed chlorin if a full output of strong bleach is maximum output of high strengthbeing produced and finally the working costs I -are necessarily high.

-According to `my inventionY bleaching powder may be made of high 'strength inV an inclined rotating cylinder which in respect of length may be compared with the tube mills used in cement works. The best len h appears to be about 80 feet, which is dou le that suggested in Hendersons aforesaid specification. The necessity for this great length is chiefly owing to theneed for thorough stirring of the partially chlorinated lime as it .descends the c linder and more particularly is it needed t at the stirring should be prolonged while the material is in the presence of the most concentrated chlorin, namely in the lower half of the length of the cylinder. Mere lengthening of the cylinder as coinparedwith Hendersons suggestion does not, however, insure a satisfactory product or fulfil the requirement that the chlorin must be substantially completely absorbed. It being necessary to work on the. counter-current principlev the chlorin must hel admitted at the bottom of theY cylinder and there is considerable difficulty in causing the chlorin to travel up the cylinder unless it is under such pressure that leakage from the cylinder cannot be avoided. `This diiiiculty is overcome in my invention by connecting an outlet at the top of the cylinder with a suction v power so as to maintain a slight suction in the cylinder.

lVithout minimum length I may say that for satisfactory results a rotatingl tube not much shorter than 80 feet must be used. A suitable inside diameter is 20 inches. Such a tube or cylinder is illustrated in the accompanying drawings, in which Figure 1 is a longitudinal sectie-n and Fig. 2 an end elevation.

The cylinder a, bolted together, as at made in cast iron sections b, is mounted in wellknown manner on roller bearings c at an ap-` propriate inclination, say 1 in 24. It is caused to rotate by worm gearing d at the rate of, say, thirty revolutions per hour. The cylinder is lined -with glazed earthenware tiles w. It is connected at its ends by means of glands e with stationary boxes f, g respectively. The box f has an opening h for exhaust of gases and an opening which limiting myself to1 an exact ter is rotated by gear m from the cylinder a and conveys the lime from hopper n to pipe z' down which it falls onto an inclined chute o and then into the cylinder a. The lime in the helical conveyer Z forms a sufficiently gas-tight packing.- A suitable rate of feedl of the limey in an apparatus of the dimensions here given is about 8 tons per week in warm weather and 10 tons per week in cold weather. The box g has an upper opening p for admission of gases and the lower opening `connected with a pipe g closed at its lowerV end by a slide v which is` opened intermittently to permit the finished bleaching powder to fall into the cask s. Inspection doors t are provided in the cylinder a. The boxes f and g have laterallyv extending brackets u supported .by posts o carried by brackets w on the uprights which carry theend roller bearings c.

The exhaust opening L in the box f is connected with a suction pump so as to draw the gases away from the apparatus and maintain a slight suction therein, to assist thev upward travel of the chlorin and prevent escape of chlorin.

Having thus described the nature of the said invention and the best means I know of carrying the same into practical effect, I claim A process for the manufacture of bleaching powder, which consists in causing lime to travel down an inclined rotating tube about 8O feetlong and causing chlorin to travel up the tube by applying a slight suction at the upper part of the tube. l

'In testimony whereof I have 'signed my name to this speciication in the/presence of two subscribing witnesses7 JOSEPH WILLIAM MOORE.

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