Prof. S. V. Lebedev and N. F. Ivanov.

Sugar losses in the hydraulic transport of frozen sugar beet, frozen for a long time under the temperature conditions of the Siberian winter.

Sugar losses in the hydraulic transport of frozen sugar beet that has been frozen for a long time, without thaws, under the natural conditions of the Siberian winter constitute a question to which neither the production practice of sugar factories nor the specialized literature of the sugar industry can as yet give any definite answer, an answer needed at the present time for the Altai sugar factory now under construction. The reason for this lies in the fact that beet frozen under the conditions of the Siberian winter and kept for a long time in this state during the production campaign, being the natural raw material for Siberian sugar factories, appears to be profoundly changed in its usual properties, composition, and structure. This makes it possible to expect the possibility of different losses of its sugar in the hydraulic transporter not only in comparison with fresh, unfrozen sugar beet, but also with respect to frozen beet encountered episodically in the practice of individual sugar factories of the existing European beet-sugar regions. If one takes into account the uncertainty and diversity of the freezing conditions of sugar beet and, in addition, considers the inevitability of its thawing, often with repetition of these phenomena, it becomes clear that the sugar industry has been deprived of the possibility of associating anything definite with the idea of “frozen beet.” This also explains the extreme scarcity, vagueness, and often inconsistency of individual data in the sugar-industry literature concerning frozen beet. There are still fewer data on the loss of sugar from such beet in hydraulic transporters. Under these circumstances it is obvious that the question of losses in the hydraulic transport of frozen beet under the Siberian conditions of its freezing is, naturally, already entirely open and requires appropriate clarification either by practical or by laboratory means. Such a requirement is connected with the fact that the losses mentioned may prove, as can be expected, quite significant, having a certain influence on the profitability of Siberian sugar factories. Under such conditions it is entirely natural that, for the latter, under special purely Siberian conditions, new requirements may arise for known changes either in factory equipment or in production-technological processes, with the aim of reducing or eliminating, by one means or another, the above-mentioned losses of sugar from frozen beet in hydraulic transporters.

In the recently published monograph Hydraulic Transporters, Prof. Kukharenko and Litovchenko provide a summary of the little that has appeared in the literature on the question of interest to us in the present case. Without touching here upon the list of names of individual investigators and the details

of their experiments, we shall note only the most important findings they contain on losses in hydraulic transport of both fresh and frozen beet. For fresh beet under factory operating conditions, Prof. Klassen determines this loss to be within the limits of 0.02–0.03%, with a maximum of up to 0.05% of the beet weight. With frozen beet, Klassen observed a sharp increase in sugar losses in hydraulic transport, reaching up to 0.6% of the beet weight. E. Carlson regards as the normal loss of sugar by fresh beet in hydraulic transport, when its length is 400 meters and the water is cold, 0.02 to 0.05% of the beet weight, whereas the same losses for frozen beet under conditions of warm water and with a transporter length of up to 1000 meters are taken by him to be up to 0.02% and more of the beet weight. Bodri, for 10 minutes at a water temperature of 18°, established a loss of sugar by frozen beet of 0.6–0.7% of its weight. Mitelman determines the corresponding value as 0.4–0.7%.

The results of the experiments, both of the investigators mentioned above and of others, while differing from one another in the numerical value established for the loss of frozen beet, all unanimously confirm the general proposition concerning the sharp difference in the magnitude of these losses in hydraulic transport between unfrozen and frozen sugar beet. Whereas, on average, the former loses 0.02–0.05%, frozen beet under the same conditions loses up to 2.0% and more of its weight. Moreover, the majority of authors, as well as Prof. Klassen, emphasize that the predominant significance in this respect belongs to the condition of the beet. And since the condition of sugar beet subjected to prolonged freezing under the conditions of the Siberian winter is quite peculiar, unusual, and unknown to the sugar industry, the losses of such frozen beet will therefore, one may suppose, be entirely different from those in the investigations listed above.

In our attempt to resolve this question, we were unable to conduct the corresponding experiments on any factory hydraulic transporter under Siberian conditions, since only now is the first sugar factory in Siberia being built. Therefore the question posed must be resolved purely by laboratory means, which we shall discuss below.

To carry out the experiments on a laboratory scale, it was necessary to construct an apparatus in which, for frozen sugar beet, it would be possible to create the same conditions as those present in a factory hydraulic beet transporter and on which the magnitude of sugar losses by the beet depends. Such factors are the absolute velocity of the mixture of water and beet and the relative velocity of the water and beet. The absolute velocity determines the duration of the beet’s stay in the water of the transporter; by the relative velocity is established the quantity of water that participates in washing sugar out of the beet. With regard to relative velocity, Woynich-Syanozhetsky says that beet roots, owing to their own inertia and mutual collisions, move at a speed 30% lower than the speed of the water. This relative velocity was also realized in our apparatus. The two other factors that can affect sugar losses by beet—the time the beet remains in the water and the temperature of the water—are determined by the assignment, and their realization presented no difficulty.

The construction of the original apparatus, designed according to the idea of Prof. S. V. Lebedev, is given below.

A long box made of galvanized sheet iron, measuring 660 × 180 × 260 mm, above the bottom of which, at a distance of 75 mm, there is a horizontal partition, also of galvanized sheet iron, dividing the space of the box into two parts—upper and lower. In this partition there are two openings—one round, 160 mm in diameter, and the other quadrangular, measuring 82 × 170 mm. The round opening has, along its edges at the top, a rim 32 mm high. The blades of a screw propeller enter the round opening; the propeller is set in rotation by means of a pulley mounted on its shaft and a transmission wheel with a driving belt from an electric motor.

Experimental laboratory water beet transporter of the system of
Prof. S. V. Lebedev.

The speed of rotation of the propeller is regulated by imparting, by means of a rheostat, a given number of revolutions to the motor shaft. When the propeller rotates, it imparts translational motion to the water and thus creates circulation of water in the apparatus. The water moves between the bottom and the partition of the box, then rises upward through the round opening in the partition and, above it, already moves in the opposite direction as a result of the same translational and, in this case, suction action of the propeller; thereafter the motion of the water is repeated in the same order. In order to

to ascertain the vortex motions of the water produced during operation of the screw; a water cutter is attached to the side wall of the box in which the screw operates.

The entire apparatus as a whole is mounted on an iron frame. Under the bottom of the box there is a gas burner. The total capacity of the apparatus is 30 liters. The working capacity is 20 liters.

The velocity of water movement in the apparatus is determined by means of a Woltmann current meter made by Amster. Every 25 revolutions the current meter closes a circuit into which a cell and an electric bell are connected; when the circuit is closed, the bell rings. The time elapsing from one ring to the next is counted in seconds by a stopwatch, and the average of several readings is substituted into the formula:

\[ V = 0.047 + \frac{8.225}{t}, \quad \text{for } t > 19, \]

where \(V\) is the velocity and \(t\) is the time.

In carrying out the experiments, the water velocity in the apparatus, with small deviations to one side or the other, was 0.25 mm per second.

From the description given it is evident that the constructed apparatus is, as it were, a laboratory water beet transporter, which makes it possible to set up a series of interesting experiments for the study of various questions connected with the movement of water, of beet, their mutual relations, and so on, under the conditions of a factory beet transporter.

The procedure and conditions for carrying out the experiments were as follows: first of all, water was poured into the apparatus up to the mark corresponding to a volume of 20 liters; then the water was heated to the desired temperature. After this, beet was taken from cold storage (2 roots), its temperature was noted (more precisely, the temperature of the air where the beet was located); the beet roots were quickly weighed beforehand and were immediately placed in the water of the apparatus on wires, the time being noted; by bringing the rheostat handle to a definite position, the water in the transporter was given a velocity equal to 0.25 m per second. Ten minutes after the beginning of the experiment, the first water sample was taken; after 20 minutes, the second; and after 30 minutes, the third. Before taking the third sample, the beet was removed and the degree of its thawing was immediately determined.

Determination of the degree of thawing of the beet was carried out as follows: the beet was cut in the longitudinal and transverse directions, and from its external appearance, as well as by touch, the depth of thawing of the beet root was determined, the thawing boundary being distinguished easily and clearly.

The unthawed part of the beet was outlined with a chemical pencil, and the distance to it from the head and from the side surface was measured in mm. When the beet lay for a short time in the air, the thawed part of the beet became reddish in color, while the unthawed part remained unchanged. Next, the water samples taken from the apparatus were filtered to remove impurities for the determination of sugar in them, and then the determination itself of the quantity of sugar in these water samples was carried out.

The determination of sugar in the water samples taken was carried out by Bertrand’s method. With frozen beet, in most cases this was done without preliminary evaporation of the water. In cases, however, where it was necessary to increase the concentration of sugar in the water from the apparatus, the latter was evaporated to a certain reduced volume as compared with the initial volume. Initially this was done at ordinary pressure; later, for fear of possible sugar losses, the evaporation was carried out in a flask under reduced pressure.

The results of the experiments are presented in Tables I and II.

Table 1.

Sugar losses, in weight percent of frozen beets, during thawing for 10–20–30 minutes in water at 20°C and 0.25 m/sec flow velocity, in a sectional unit and in various temperature conditions.

¹ After 10 min in quiet water.
² After 5 min in quiet water.
³ The first 5 min in quiet water.

The quality of the sugar beet used in the experiments was characterized by a purity of normal juice of 82.4–83.9, in individual cases falling to 81.6, with the sugar content in the beet ranging from 15.6 to 17.7%.

In Table II below are given the results of several experiments in which the beet was in still water. These experiments were carried out in order to determine how the motion of the water affects the sugar losses of frozen beet.

Table II.

Sugar losses of frozen beet in still water.

From the data presented it is evident, first, that sugar losses in still water, when compared with sugar losses for beet located in flowing water, at the same water temperatures and the same residence time in it, are approximately 2–2.5 times smaller; second, that the amount of still water into which the beet was immersed is not reflected in the magnitude of the sugar losses of the beet. This indicates that the increased sugar losses when beet is washed with flowing water occur because, in immobile water, mainly the water only immediately adjacent to the beet surface participates in the extraction of sugar, whereas, with motion, a much larger mass of water comes into contact with the beet surface, and therefore the extraction of sugar from the beet proceeds more intensively here.

The beet taken for all the experiments, when cut lengthwise, was dense and frozen in the middle of the root and had an entirely fresh appearance, whereas near the surface of the root its mass appeared thawed, loose, and as if porous.

The experiments presented in Tables I and II were carried out exclusively with beet frozen through in Siberia. The magnitude of the losses found in hydraulic transport was established under the conditions of a laboratory transporter designed by Prof. S. V. Lebedev, which in its operation reflects to a considerable extent what is characteristic of factory hydraulic transport of beet.

Thus, it is possible to compare the sugar losses of fresh beets, established by factory practice, with those found in the experiments under consideration in the laboratory study. But in order to make this comparison still more definite, in the winter period of 1929/30 parallel experiments were also set up: on the one hand, with unfrozen sugar beets that had been kept in a cellar at a temperature of about \(+3^\circ\)–\(+4^\circ\); on the other hand, with the same kind of beets, but ones that had frozen for 2 to 4 weeks during December–January directly under the natural conditions of the outdoor air of Siberia in winter. These beets were immediately frozen at a temperature of \(-24^\circ\text{C}\).

The results of these two series of experiments, carried out under identical conditions in the above-described laboratory hydraulic transport, with the previously established relative water velocity of 0.25 meters per second, are given below.

Table III.

Sugar losses in % by beet weight.

The corresponding data for beets that had frozen for about two weeks outdoors at minus \(25\)–\(30^\circ\text{C}\) are given in Table IV.

In this table are given the sugar losses of frozen beets by their weight at temperatures from \(-10^\circ\) to \(-50^\circ\text{C}\), inclusive, for durations of residence in the hydraulic transport from 10 to 40 minutes.

Table IV.

Sugar losses in % by beet weight.

Table V.

Sugar losses in % by weight of beet.

Tables IV and V show that the sugar losses from frozen beet increase with a rise in the temperature of the water and with an increase in the duration of the frozen beet’s stay in the water, and also in connection with a lengthening of the freezing time.

The initial temperature of the beet, both in these experiments and in those carried out earlier, did not exert any noticeable effect on the magnitude of the sugar losses from the beet.

To determine how quickly the effect of freezing of the beet appears in increasing the losses of its sugar in hydraulic transport, experiments were set up with short-term freezing of the beet, with severe cooling immediately following, for a period from 6 to 24 hours, and then for two, three, and four days. The cooling was carried out by subjecting beet taken from the cellar, where it had been stored at a temperature above 0°, to the action of outdoor air at minus 35° and below—down to minus 48° C.

Beet frozen in this way was placed in the laboratory hydraulic transporter of the indicated design, where it was kept for 20 minutes for each sample of a definite freezing duration. The results of this test are presented in Table VI.

From Table VI it is evident that already 6 hours of freezing at minus 36° C quite definitely increase the sugar losses in the beet during its twenty-minute stay in the hydraulic transporter at 30° and 50° C.

Table VI.

Sugar losses in % by weight of beet.

Conclusions

On the basis of the experimental data obtained concerning sugar losses in the water of a hydraulic transporter for beet that had been frozen and then stored for a long time under the natural conditions of a Siberian winter, the following conclusions may be drawn:

1. Sugar losses in the water transport of frozen beet are considerably higher than the corresponding losses for normal, unfrozen sugar beet.

2. Even short-term freezing of beet for several hours contributes to a noticeable increase in the above-mentioned losses.

3. These losses are considerably smaller in still water than in moving water.

4. Sugar losses of frozen beet in water transport increase with:

a) an increase in the duration of freezing of the beet;
b) a decrease in the freezing temperature;
c) an increase in the time during which the beet remains in the transporter;
d) an increase in the temperature of the water in the water transporter.

1. At water temperatures of about \(50^\circ\mathrm{C}\) and a duration of beet immersion in water of 30 minutes, the depth of thawing of the beet reaches up to 30 mm into the root, decreasing as the temperature is lowered and the time is shortened.

2. The initial temperature of the frozen beet has no noticeable effect on the magnitude of its sugar losses or on the depth of the thawed layer of its root.

Tomsk.

Laboratory of Food Substances
of the Siberian Technological
Institute.