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7
Section 10. Technical sciences
Starykh Daria, student, the Faculty of Technology Tambov State Technical University E-mail: dariastaryh@yandex.ru Ivanova Anastasiya, student, the Faculty of Technology Tambov State Technical University Cherkaeva Margarita, student, the Faculty of Technology Tambov State Technical University
THE PROBLEM OF REMOVAL OF DEPOSITS FROM HEAT EXCHANGE SURFACES AND THEIR GRINDING
Abstract: Data on the character of formation of deposits on heat exchange surfaces are presented. The main methods of cleaning contaminated surfaces are shown. Methods of waste treatment and utilization are presented.
Keywords: heat exchange, surfaces, methods, waste treatment, utilization.
In the process of ethyl alcohol production the main waste is liquid after-alcohol bard. The yield of the bard can reach 390 tons per day with the capacity of the distillery in 3000 dal of alcohol per day. In the technological process of utilization of liquid bard, on the walls of the heat exchange equipment, solid deposits are formed, which are difficult to separate from the surface. The rate of growth of these deposits strongly affects the efficiency of the devices and generally limits the performance of the entire distillery as a whole.
To date, the most common method of disposal of bards is a technology that includes the use of centrifuges, evaporators and dryers. The main problem of this technology is the rapid formation of deposits of the processed bard on the walls of the heat exchange equipment.
In order to develop recommendations for the operation of existing technological equipment and the possible use of new designs, we have set the following tasks:
1. Creation of new experimental facilities that simulate the formation of deposits on different heat exchange surfaces under different operating conditions;
2. Development of recommendations to reduce the rate of growth of deposits on the walls of technological equipment.
As our studies of drying kinetics on liquid bard substrates have shown, the formation of certain structures is observed. At all investigated modes of drying of a surface of the dried-up bard the thin film is formed.
The structuring of the solid phase in the film continues throughout the drying process. A similar phenomenon is observed on the walls of heat exchange equipment, for example, in evaporators [1].
To determine the effect of the process modes, methods of mechanical and thermal treatment of liquid bard on the
experimental setup developed by us, simulating the operation of typical shell-and-tube heat exchangers and tubular film evaporators, studies were conducted that simulate the process of occurrence and development of deposits of dried bard on the walls of the heat exchange equipment [2].
The analysis of the obtained values showed that the adhesion value for the corn bard is less than that of the grain bard by 4-10 times.
An increase in the temperature of the heat exchange surface leads to an increase in the adhesion value by 1.5-3 times [3].
The main mechanical processes of chemical technology include grinding of solid materials and classification (sieving) of bulk materials.
There are: crushing (final particle size about 20 mm) and grinding (smaller particles). There are also: large, medium, fine and colloidal grinding. Apply accordingly: crushers (e.g., cheek, roll, etc.) and mills (e.g., runners, rotating drum mills with grinding balls, finger disintegrators, colloidal bead mills ofwet grinding with small glass balls, ultrasonic grinding, etc.).
Classification is the separation of a mixture of particles into fractions by particle size. Apply: mechanical classification (screening, screening) on sieves, sieves, perforated drums, etc.; hydraulic classification in hydrocyclones, sedimentation tanks; air classification (separation) - in jet machines, cyclones, separators.
Grinding is a very energy-intensive process. The power consumed for grinding depends on the properties of the material and the multiplicity of grinding.
Specific energy consumption for grinding they consist of the cost of elastic and plastic deformation e and the cost of increasing the surface of the material to be ground and the specific surface energy.
THE PROBLEM OF REMOVAL OF DEPOSITS FROM HEAT EXCHANGE SURFACES AND THEIR GRINDING
Therefore, the main rule when grinding - do not grind. In addition to unnecessary energy costs, the quality of the crushed product often deteriorates, and the trifle and dust can lead to clumping, sticking, sintering during further processing.
In industry, usually use a sequential scheme of coarse, medium, fine grinding with intermediate classification (sieving), with the removal of the cycle of particles required (or less) size and return (recycle) of the particles to re-grinding (fines are sometimes sent to the agglomeration).
References:
1. Konovalov V. I., Pakhomov A. N., Gatapova N. Z., Kudra T. Drying of Dispersed Systems in Thin Layers-Process Mechanism and Kinetics // 12th Internat. Drying Symposium IDS'2000.- Netherland, 2000.- Amsterdam: Elsevier Science, 2000.-Abstracts, Papers CD-ROM.- Report - No. 397.- 6 p.
2. Konovalov V. I., Gatapova N. Z., Shikunov A. N., Utrobin A. N., Pachomov A. N. and Leontyeva A. I. Drying kinetics of liquid dispersions from thin organic syntheses on various substrates, Proceedings, 13th International Drying Symposium, Beijing, China, August 28-31, 2002. - Vol. A.- P. 226-231.
3. Konovalov V. I., Gatapova N. Z., Koliuch A. N., Pachomov A. N., Shikunov A. N., Utrobin A. N. Kinetics of conductive drying and heat-transfer on contact cylinders // Proc. of the 14th Intern. Drying Symp. (IDS'2004). - Brazil, - Aug. 22-25, 2004.- Vol. A.- P. 247-253.
