US817010A - Method of crystallizing sugar, &c. - Google Patents

Description

PATENTED APR. 3

V. H. SOHUTZE. METHOD OF GRYSTALLIZING SUGAR, 6a

APPLIGATION FILED APR. 24. 1905.

Ill ttttt nrrnn STATES PATENT OFFICE.

vIo'roR HERMANN SCHUTZE, OF RIGA, RUSSIA.

METHOD oF CRYSTALUZING SUGAR, &c.

Specification of Letters Patent.

Patented April 3,1906.

Application filed April 24,1905- Serial No. 257,280.

To all whom it may concern.-

Be it known that I, VICTOR HERMANN SOHUTZE, a subject of the Emperor of Russia, residing at Riga, Russia, have invented certain new and useful Improvements in Methods of Cr stallization; and I do hereby declare the ollowing to be a full, clear, and exact description of the invention, such as will enable others skilled in the art to which it appertains to make and use the same.

In the specification of Letters Patent No. 780,448, for an improved method of crystallization, granted to Victor Schl'itze, January fss 17, 1905, is described a process of obtaining large well-formed crystals from hot saturated solutions, the essential feature whereof consists in this, that the hot saturated solution moving continuously and slowly is met by a liquid, such as water, surrounding the same, which acts simultaneously as a cooling agent and as a jacket for retaining the heat on the counter-current principle, so that the difl'erence in temperature between the solution and the cooling liquid is uniform and relatively slight. The present invention relates to an improvement upon this process which is based on the following known physical laws: First, the boiling-point of a solution depends on the degree of concentration. and on the pressure of the surrounding atmosphere; second, the degree of viscosity of a liquid is under like conditions of air-pressure dependent on the temperature and under like conditions of temperature is dependent on the air-pressure. Accordingly under the process forming the subject of the invention, which is adaptable for all crystallizable, organic, or inorganic substances, especially, however, for the obtaining of sugar direct from the sugar juice or syrup-in one operation and the removal of the molasses the operations of com centrating and crystallizing are carried out entirely to the finish in one apparatus-tbat is, in a vacuum apparatus kept in continuous motion. The mother-liquor is brought to concentration in the first part of the vacuum apparatus and is in the second part of the apparatus, while, however, remaining throughout in name, cooled down to the atmospheric temperature, or even considerably lower, so that it leaves the apparatus as a solution crystallized out as far as possible.

The apparatus serving to carry out this process, "which also forms an improvement over the construction described in the said specification, is constructed on the following principles: If a hot liquid flows in axial direction through theinner cylinder of a stationary cylindrical double-Walled horizontally-disposed vessel While at the same time flowing through the annular space will not be uniformly warmed, however, but it will become considerably warmer in the upper haltr than in the lower half-that is, than the liq-i uid flowing along the bottom. ()n the other hand, the hot liquid flowing through the inner cylinder will have a considerablyhigher temperature at the top of the cylinder than at the bottom. In order that the heating of the liquid. circulating through the annular space may proceed gradually and uniformly, indicating the like temperature at top and bottom, and that the reduction of temperature in the liquid flowing through the inner cylinder be gradual and uniform, the liquid in the annular outer space is caused to circulate in a Figure 1 is a part vertical section, Fig. 2 go a plan, and Fig. 3 an end view, of the same.

The apparatus A comprises a vessel absolutely air-tight, having double walls with a passage between the same and of elliptical transverse section. tween the walls is a spiral partition having a water-tight and air-tight connection with the inner wall a and the outer wall I) and which serves to give the required direction to the liquid serving as a heat-retainer and flowing through the annular space between the walls. The said spiral partition has a relatively slow pitch, so as to give as many turns as possible for the length of the apparatus. The distance between the walls is naturally proportionate to the size of the ap aratus. Inlet and'outlet openings 0 and cl for t 1e jacketing liquid are provided at both ends of the apparatus. The apparatus has also a manho e M, with an air-tight cover N, a couplingpiece for attaching the manometer for reading off the degree of vacuum at anyt me, a

In the inters ace be- I i I coupling-piece f for the vacuum-prim and several connections for attachment 0 thermometers. Further, the apparatus has an inflow-pipe E with a hermetically-closable valve 0 for the sugar solution to be concentrated and crystallized and an outflow-pipe k, to which is attached a hermetically-closable'cylindrical receptacle B, preferably of glass, for the crystals delivered from the apparatus along with the mother-liquor. This receptacle B has also a connection m, which terminates in a hermetically-closin valve or cock, and has also two cocks Z and%. The entire vacuum apparatus is rotatable around its horizontal longitudinal axis and must receive a slow rocking movement, which is in the present case imparted by the lever-arm 'n.

In the treatment of sugar solution the operations are as follows: The syrup purified by diffusion, separation, saturation, and filtration and evaporated to 48 to 50 Brix.flows from the evaporating apparatus through the desired vacuum.

pipe E in a continuous stream regulated. by of about 7 09. into the vacuum apparatus A. the operation, however, heat-retainer is led centigrade, Before commencing the liquid serving as a from c at a, tem erature of about 80 centigrade through t e 'jacketing-space until the quid issuing at d has a temperature of about 70 to 80, that is, until the entire vacuum apparatus has reached this temperature.

Then the supply of hot -liquid is turned off and now through the. tube 0 a cold liquid is led in a slow current into the annular space until the liquid issuing at at shows a fall in, the temperature of the ori inally hot liquid; During the passage of iquid through. the jacket the vacuum-pump is set in motion in orderto bringthe vacuum apparatus to the At this time naturally the valve '0 in the tube E and also the valve between the apparatus A and the receptacle B must be closed. From the manometer itican be determined whether the apparatus 1 is closed hermetically, and the valve is' then opened and the .hot syrup is permitted to flow into the slowly oscillating vacuum apparatus. The inflow of syrup .is so regulated that in the interior of the apparatus a vacuum as constant 'as possible is maintained.

' The manometer should indicate no air-pressure greater than seventy millimeters of mercury.

is in the apparatus boils and gives 0 part of its water content as vapor to the evacuated s ace. This vapor is at once drawn off by t e vacuum-pump, which always endeavors to maintaln the same vacuum. The hot syrup :of the apparatus,

.with mother-liquor, which,

moving in the apparatus toward the outlet meets at the next point a part of the inner wall having a temperature of about 69 centiade and must therefore give up part of its eat, but .at the same-time warms'with the heat given ofl the liquid slowly flowing through the outer jacket and having at this point a temperature of nearly 69 centigrade. The sugar solution having still a temperature of 69 flowing farther toward the outlet meets at the next point apart of the inner wall having a temperature of only 68 centigrade .and gives up again part 'of its heat, cools somewhat, and at the same time warms the jacketing liquid. On the other hand, the sugar solution is concentrated in the vacuum apparatus, and, on the other hand, it is cooled; but not only does concentration take place in the vacuumapparatus, but also crystallization and growth of the separated sugar crystals. The syrup entering with a concentration of 48 'Brix. and with a temperature of about 7 0 centi ade boils in the vacuum ap aratus, and is t us concentrated further, an if this concentrated solution is now cooled then naturally as the solubility of the sugar increases with the temperature a part of the sugar must separate out. As in the vacuum apparatus there are the conditions necessary for good crystallizationnamely, as small as possible diminution of temperature and least possible movement the crstals separate in good forms. The

crysta sv come in contact with the solution and gradually grow in size. On'the inner wall of the a paratus new crystals are always forming. T ese crystals deposit on the foot but do not adhere, but mi grate. or wander, as the entire apparatus is in continuous slow motion, and arrive at the outlet of the apparatus after following a double .or circuitous path. They move inQa wavy route toward the outlet, wanderin .at thesame time and increasing in'size an acquiring a-larger surface. tals reach the outlet-nozzle and leave the they are surrounded however, will not be viscous, because there. is a vacuum vacuum apparatus,

throughout, and, the. viscosity of a solution 1 is "not only a function of the temperature, but. also a function of the external pressure. On'lea'vmg the aplparatus the crystals fallinto the receptacle which is also evacuated.

When B is about two-thirds full .of crystals, I

the valve 1: is closed and the valve m opened, and by 0 ening the valve 1 the crystals in the rece tac e B are caught on a sieve, the mot er-liquor being allowed to drip ofi and the crystals are separated in a centrifugal] machine with only a little water. The crystals so obtained are of chemicallypure sugar in beautiful transparent forms.

The rocess is not only applicable to treat ment 0 sugar solutions, but also to all other 1 When the crys 1 causing organic and inorganic crystallizing' substances.

Having now particularly described and ascertained the nature of my said invention and in What manner the same is to be performed, I declare that what I claim is The method of obtaining crystals from a hot saturated solution, which consists in said solution to slowly travel under the in uence of a vacuum through an elliptical vessel which is steadily rocked and simultaneously causing a cooling liquid to travel in, a helical path around the outside of said vessel in the opposite direction to the flow of said solution, substantially as described.

In testimony whereof I afiix my signature in presence of two witnesses.

VICTOR HERMANN SCHUTZE. Witnesses: OONSTANTIN PYoHLAU,

LUnw. EH'RTMANN.

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