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14
S = A-10-
V P J
Coefficient for the red beet A = 1.275, the exponent m = 2.08 and n = 2.245, and for sugar beet respectively — A = 4.52, the exponent m = 2.11 and n = 1.7. Equation is valid in the following range of operating parameters: relative pressure steam P/P0 = 1.4-4.0 and a relative of the original moisture content of W0 = 5.4-6.9. The error in the above formula range of operating parameters shall not exceed ± 6.9 % (see fig.3).
Visual observations and experimental studies showed that the method provides instant pressure relief in the form of efficient treatment failure scraps thin skin over the entire surface of tuber, except for the top,
i. e. places sprouting leaves. Feature of the method of in-(1) stantaneous pressure relief in the fact that it cleans pure eyes and even deeper place, filled with sand and soil. In addition, the presence of different types of litter and pollution raw material does not affect the efficiency of the process. Therefore, before clearing roots there is no need to process cleaning operations of raw materials from organic and metallic impurities, rocks and dirt.
Another distinctive feature of this method is that the purified tuber is not cooked, i. e. raw. Adhering after cleaning the pieces of skin can be easily removed in the process of hydraulic classification. This is a positive factor, as loss of raw materials decreased by 3-5 times. Preliminary studies on the treatment of other tuber roots also showed positive results.
References:
1. Магомедов Г. О., Петров С. М., Бывальцев А. И. и др. Новые способы получения продуктов из сахарной свеклы//Сахар. - 2003. - № 6. - С. 54-56.
2. Patent Germany № 3913172, МПК5 A23N 7/00, A47J 17/00. Verfahren zum mechanischen Schalen von Erdoder Baumfruchten in Schalmaschinen//Dornow Karl-Dietrich. - P. 5.
3. Ковалев В. С., Воронков В. И. Промышленное производство продуктов питания из картофеля. - Киев: Урожай, 1987. - 80 с.
4. Переработка картофеля - стратегический путь развития картофелеводства России/Под общей ред. В. И. Старовойтовой. - М.: Техноэликс, 2006. - 156 c.
5. Остриков А. Н., Калашников Г. В., Калабухов В. М. Динамика качественных изменений в картофеле и овощах при влаготепловой обработке//Хранение и переработка сельхозсырья. - 2005. - № 7. - С. 24-26.
6. Колесников В. А., Лысый Н. А., Павлов П. П. Новые пищевые продукты из сахарной свеклы//Сахар. -2008. - № 2. - С. 34-39.
7. Абдуллаева С. Ш., Нурмухамедов Х. С., Абдуллаев А. Ш. Очистка корнеплодов методом мгновенного сброса давления//Химическая технология. Контроль и управление. - 2008. - № 4. - С. 28-30.
3
D OI: http://dx.doi.org/10.20534/AJT-17-1.2-69-71
Abdullaeva Sadokat Shonazarovna, senior research associate - the researcher, Tashkent chemical-technological institute, Department of «Processes and apparatuses of chemical technology»
E-mail: [email protected] Nurmuhamedov Khabibulla Sagdullayevich, Doctor of technical sciences, Professor, Tashkent chemical-technological institute
The dehumidification during crushing of the peeled pulp root crops by method of instant dumping of pressure
Abstract: The results of experimental research on influence of relative pressure P/P0 and further relative humidity 9 of raw materials and time of dumping t of pressure upon degree of crushing and final humidity of the product are given in the article. The analysis of influence of parameters on dehumidification in the
course of receipt of puree from root beets has also been carried out by the method of instant dumping of pressure (MIDP).
Keywords: dehumidification, heating rate, method of instant dumping of pressure, puree.
The processes to obtain of a ready-made product or a semifinished product by sharp change of pressure of the environment which placed the processed material in the food industry and other industries of production have been widely started to apply. Depending on appointment, the effect of dumping of pressure provides or drying [1, 79], crushing [2, 35-42] or hardening [3, 28-44] materials, by means of the maximum use of effect of intensive molar transfer of steam. The material is heated under the pressure which then decreased. The boiling of moisture and steam formation are resulted due to the accumulated heat in all weight of object. By regulating of boiling process, it is possible to achieve that the process is made destruction or modification of structure and properties of material [4, 135]. In general, by crushing solid materials, the method is implemented as following: heating the material with its moistening and swelling, dispergating and drying of obtained product.
Physical basis of this method is the effect of intensive molar transfer of steam which is observed after preliminary heating of damp material under pressure and it is later rapid decreasing [3, 135]. A change of aggregate state of moisture is occurred at the time of dumping of pressure in all volume of the material, therefore between the center and a surface of an object of processing is formed differential pressure, and contributing to form directed to particle surface of a stream in the form of steam and liquid.
Conditions for realization of transfer of free moisture are created by physical and chemical changes of structure of damp material by its high-temperature heating under pressure. These changes of structure which takes place by heating of a sample proceed almost instantly with achievement of temperature necessary to start these transformations.
Increasing of initial moisture content material is led to increase of contents in an object of free moisture that leads to increase in pressure gradient which is formed by dumping. Gradients of temperature, humidity and pressure are proceeded in one direction, causing migration of moisture within material, leading it to be removed [5, 8-13].
The effect of dehydration with identical pressure is defined by a type of material as well as eventually its colloidal and capillary and porous structure [4, 141]. According to the researchs conducted by a number of
authors [3, 28-44; 6, 118-121], dumping of pressure allows to reduce the containing of moisture several times in comparison with initial depending on structure and properties of material. Intensity of dehydration of material significantly depends on the rate of dumping of pressure [4, 143].
In fig. 1 the results of pilot studies on influence of relative pressure P/P0 , initial relative humidity 9 of raw materials and time of dumping t pressure upon extent of [7, 9-12; 8, 355-357] and final humidity of a ready-made product crushing are given.
1 X
N 1
10° 2 4 6 8 101
t = 0.070 s: ° - a = 0.68, a - a = 0.57, □ - a = 0.507;
T init. ' T init. ' T init. '
t = 0.005 s: • - a.. = 0.68, A - a . = 0.57, ■ - a . = 0.507
Tinit. ' Tinit. ' Tinit..
Fig. 1. Dependence of relative humidity from pressure of saturated steam by crushing potatoes
with the method of instant dumping of pressure
By processing potatoes in mashed potatoes with the method of instant dumping of pressure at initial relative humidity a = 0.678 and time of dumping of pressure t = 0.07 it has the following results: at a relative pressure of saturated steam P/P0 = 3.4 value of relative humidity a = 0.48, at P/P0 = 4.0 forms a = 0.51, and, at last, at P/P0 = 6.0 relative humidity it is equal a = 0.415. Similar dependence is received also for initial relative humidity a = 0.51.
So, with a relative pressure of saturated steam P/P0 = 3.4 equal a = 0.37 and at P/P0 = 6.0 — a = 0.315. It is clear that by growing of relative pressure of saturated steam with P/P0 = 3.4 to 6.0 intensity of dehumidifica-tion forms 1.15-1.22 %.
By experimental studies on receiving puree of potatoes it is established that by reducing of time of dumping
t pressure of saturated steam from the reserved system process of dehumidification is intensified.
Comparison of experimental data shows that at P/P0 = 4.0 and initial humidity 9 = 0.678, final humidity at time of dumping pressure t = 0.07s is equal 9 = 0.51, and at t = 0.005 s — 9 = 0.285. It is clear, decrease in time of dumping of pressure leads to intensification of dehumidification process ~1, 8 times. The analysis of results for other values of relative pressure of saturated steam P/P0 and humidity 9 has shown that degree of intensity of dehumidification fluctuates within 1.5-2.2.
The analysis of experimental data shows that degree of dehydration of root crops pulp significantly depends on the rate of dumping pressure of saturated steam from the reserved system.
Similar experimental data on dehumidification by crushing with the MIDP are obtained for sugar, red beet and carrots. For these two products regularity of change of relative humidity also remains by crushing with the MIDP.
Explanation of high values of dehumidification in the following: with increase in excessive pressure of the heating steam rate of heating dt/dT increases, is proceeded rapid penetration of the front of high temperatures deep into of pulp and intensive moistening of a thin skin. Naturally, at the same time for a high temperature of the heating steam and rather low temperature of pulp a root — or a tuber crop occurred the gradient of temperature which is directed in object of processing.
References:
The object of processing surrounded with saturated water vapor with pressure P/Patm>0 has the temperature front, and inside of the object pressure is P/Patm = 0.1. In other words the gradient of pressure of grad P is directed into an object. The humidity vector has the same direction as well as working agent is saturated water vapor U >U .
i steam mat
After boiling of an object on a small depth is made dumping pressure of saturated steam from the reserved system to the environment. It should be noted that at the time of dumping of pressure in a pulp of root crop owing to the formed grad P differential pressure grad P = P2 - Patm aggregate state of superheated liquid in steam instantly changes. At the same time this phenomenon forms vapor-liquid a stream in the form of the smallest droplets of water and steam which directed from within outside. The amount of the formed water vapor at MIDP directly depends on temperature of the heating steam which much more temperature of boiling of water and temperature of pulp a root — or tuber crops.
At the time of dumping ofpressure the above-named gradients of temperature of gradt, pressure of grad P and humidity ofgrad U are directed outside, i. e. from the center of an object of processing to its surface.
Thus, crushing of the deformed materials by method of instant dumping of pressure allows to obtain the crushed mass of necessary humidity and dispersion.
1. Плановский А. Н., Муштаев В. И., Ульянов В. М. Сушка дисперсных материалов в химической промышленности. - М.: Химия, 1979. - 288 с.
2. Рабинович Д. И., Геллер З. И. Размол топлива методом сброса давления//Науч. запис. Одес. политех. инта. - 1960. - т. 22. - С. 35-42.
3. Шангареева Е. Ю. Разрушение влажных пористых материалов вследствие быстрого внутреннего испарения при тепловом ударе//ИФЖ. - 1994. - № 1. - С. 28-44.
4. Михайлов Ю. А. Сушка перегретым паром. - М.: Энергия, 1967. - 200 с.
5. Андрианов В. П., Сафин Р. Г. и др. Тепломассоперенос при сушке понижением давления//Современные аппараты для обработки гетерогенных сред. - Л.: ЛТИ им. Ленсовета, 1984. - С. 8-13.
6. Сажин Б. С. Основы техники сушки. - М.: Химия, 1984. - 320 с.
7. Абдуллаева С. Ш., Нурмухамедов Х. С., Абдуллаев А. Ш. и др. Влияние давления острого пара на подсушку корнеплодов при очистке методом мгновенного сброса давления//Хранение и переработка сельхозсырья. -Москва, 2016. - № 4. - С. 9-12.
8. Abdullaeva S. Sh., Nurmuhamedov H. S., Abdullaev A. Sh. Production of sugar beet puree by a method of instant pressure reset//5th World Conference on Intelligent Systems for Industrial Automation «W0S-2008». - Т., 2008. - P. 355-357.
D OI: http://dx.doi.org/10.20534/AJT-17-1.2-72-75
Bobokulova Oygul Soatovna, Senior teacher of cathedral «Analytical, physical and colloid chemistry», Tashkent institute of chemical technology, Uzbekistan E-mail: [email protected] Talipova Habiba Salimovna, Associate professor, Tashkent institute of chemical technology
E-mail: [email protected] Mirzakulov Kholtura Chorievich, Doctor of technical science, professor, Tashkent institute of chemical technology E-mail: [email protected]
Research of process of reception of the pure solutions of chlorides of sodium and magnesium from the dry mixed salts of lake Karaumbet
Abstract: Results of researches on reception of the solutions cleared of accompanying impurity from the dry mixed salts of lake Karaumbet are resulted. Conditions are established at which the maximum solubility of the dry mixed salts, chemical and salt contents of received solutions and solutions after cooling and branch of myrabilit, additional cleanings from sulphates with distiller liquid are established.
Keyword: dry mixed salts, dissolution, filtration, myrabilit, degree of sedimentation, desulphation.
Introduction technology of processing of lake Karaumbet DMS with
Compounds of magnesium and sodium sulphate reception of compounds of magnesium are very actual. are used in many industries. Chemical, metallurgical, For the purpose of involving of the dry mixed salts
glass, textile, power, pharmaceutical and other branches require magnesium compounds. Chloride magnesium or bischofite are initial raw materials in manufacture magnesium chloride defoliants [1]. In the absence of own manufactures of compounds of magnesium the requirement for them is completely provided at the expense of import.
Uzbekistan has enormous stocks of raw materials for reception of salts of magnesium and sodium. One of such kinds of raw materials are the dry mixed salts (DMS) of lake Karaumbet. Industrial stocks in a contour of a design open-cast mine of a deposit make 612.55 thousand t in recalculation on chloride magnesium. Dry mixed salts of lake Karaumbet on the average contains (weights, %): Na2SO4 — 43-61; MgCl2 —11-15; NaCl — 13-19; h. o. — 4-30. Except DMS huge stocks of salts of magnesium and sodium are concentrated and in leach of lakes Karaumbet and Barsakelmes [2].
Despite the big requirement for connections of magnesium and sodium sulphate, presence of a powerful raw-material base they in Republic are not made. It is connected, first of all, with absence of the developed technologies of processing of leach and the dry mixed salts. Therefore the researches directed on working out of
of lake Karaumbet in industrial production on an establishment of their solubility researches are carried out in water, clearing of solutions of accompanying salts and insoluble impurity in water, processing to hydroxide magnesium.
Objects and methods
For experiments used DMS of lake Karaumbet, contents, (weights, %): Na2SO4 — 60.69; NaCl — 18.81; MgCl2 — 15.30; MgSO4 — 0.42; CaCl2 — 0.31; h. o. — 6.98; H2 O — others. The chemical analysis on the contents of the basic components in solutions, distiller liquids, mother solutions and a solid phase spent by known methods [3-5].
For an establishment of optimum technological parametres of preparation of solutions from DMS their solubility in water depending on ratio H : L is studied, at temperature 25 °C, constant speed of hashing and duration of process of 30 minutes. The received results are resulted in table 1.
From the resulted data it is visible, that maximum solubility of DMS in water is observed at H : L = 1 : 3 and makes 93.02 % from a total mass. Hence for reception of solutions with maximum solubility of DMS it is necessary to support H : L = 1 : 3.
