Study the possibilities to increase the efficiency and decrease energy 
consumption of powerful tumbling mills

BORODAI, Valery

Бородай, Валерий Анатольевич

Бородай, В. А.

Бородай, Валерій Анатолійович

NESTEROVA, Olha

Нестерова, Ольга Юріївна

Нестерова, О. Ю.

Нестерова, Ольга Юрьевна

SHYKHOV, Stanislav

KHALAYIMOV, Taras

English

eLibrary National Mining University

90  both velocity of ions formation and velocity of convection removal of space charge. Key words: EHD flow, ion-molecular structures, high voltage, liquid dielectrics References 1. G.A. Ostroumov , About results of a measurement of electroconductivity of insulating liquids, J. Exper. and Theor. Phys., 41, №2, (1961) pp. 441-444. 2. Y.K.Stishkov, A.A.Ostapenko, Electrohydrodynamic flows in liquid dielectrics, Edd. Leningrad State University, Leningrad, (1989). [in Russian]. 3. A.A. Ostapenko, Y.K. Stishkov, Kinematics and dynamics of EHD flows, Annual Report of Conf. on Electrical insul. and dielectric phenomena. (CEIDP, 99), Austin, vol. II, (1999), pp. 344-347. 4. А.О. Ostapenko, М.O. Zhuravlyov, Effect of properties of electrode -dielectric boundary on EHD-flow // Geo-Technical Mechanics / Ukraine, № 135, (2017), pp. 92-99. 5. А.О. Ostapenko, М.O. Zhuravlyov, N.L. Kurnat, Effect of active electrode size and temperature on the kinematics of electrohydradynamic (EHD) flows // Geo-Technical Mechanics / Ukraine, № 137, (2017), pp. 117-123.   DEVELOPMENT OF AUTOMATIC SPEED CONTROL SYSTEM FOR SYNCHRONOUS DRIVE OF HIGH-POWER TUMBLING MILLS  BORODAI Valery, NESTEROVA Olha, SHYKHOV Stanislav & KHALAYIMOV Taras Dnipro University of Technology, Dnipro, Ukraine  Purpose. Study the possibilities to increase the efficiency and decrease energy consumption of powerful tumbling mills. Methodology. The studies were carried out through the justification of operating modes of tumbling mills and determination the methods of reaching their maximum efficiency by adjusting the operating mode. Findings. One of the ways of efficiency increasing of powerful tumbling mills is to improve the technology of grinding, as well as the use of more modern systems of electric drive. The grinding technology involves the following methods of minerals destruction [1]: by friction, impact, and in a combined way. The implementation of these methods in tumbling mills is created by operating modes: cascade, cataract or combined. The cascade mode of operation has the highest power consumption, followed by a combined, and the last in this list is a cataract operating mode. To increase the efficiency of the mill means to create conditions that allow achieving the maximum productivity with minimal energy consumption of the mill. It is clear that for 91  different types of input grinding material it is necessary to adjust the operating modes of the mill, which depend on the speed of rotation of the drum. The second way to improve the efficiency of grinding machines is to use a class of drive with better energy performance in the mechanism. Such type of drive is synchronous one. Its advantages, such as increased efficiency, the ability to compensate reactive power, a significant air gap, which reduces the requirements for the accuracy of the manufacturing and low speed of the shaft, thus no gearbox is needed. Traditionally, the synchronous drive of tumbling mills is set up at a rational speed for grinding minerals of a concrete deposit. As a consequence, there is no speed adjusting throughout the entire duration of the work, regardless of the changes in the properties of the input product that occur in different areas of extraction. Taking into account the current economic challenges and requirements for increasing mills’ efficiency, the relevance of creating automatic speed control systems for synchronous drive of tumbling mills cannot be called into question. Thus, the required range of velocity control does not exceed 50 % of its the maximum value, so for such a case the frequency control fully meets the requirements of the technological process. In addition, the use of a modern frequency converter’s control strategy can allow energy savings together with other methods that are mentioned above. According to the last conclusion and using the original model of the synchronous drive [2, 3], the preliminary structural scheme of the mill drive model is shown, where the parameters of the quadrature and direct armature current and speed regulators are calculated according to the classical methods of the theory of automatic control. According to the results of the research, the following conclusions should be done: - Today’s economic challenges make industry to improve the efficiency of grinding equipment; - Offered techniques for increasing the productivity of the equipment: improvement of the grinding technology by continuous adjusting of the drum operating mode depending on the hardness of the input grinding material and the attraction of more energy-saving type of drive based on the synchronous motor; - Another way to save electrical power in the proposed electric drive system can be achieved through an energy-saving control strategy that involves selecting the desired voltage value, depending on the engine load. Keywords: grinding, tumbling mills, operating modes, synchronous drive References 1. Андреев С., Зверевич В., Перов В. Дробление, измельчение и грохочение полезных ископаемых / С.Андреев, В.Зверевич, М.Перов - Недра.- 1966.- 523 с. 92  2. Бородай В.А. Компенсація різко-змінного струму якоря потужнихсинхроннихприводівзасобамиавтоматичноїсистемизбудженняізнестандартним алгоритмом керування [Текст] / В.А. Бородай, Р.О. Боровик, О.Ю. Нестeрова // Електротехніка та електроенергетика. – 2018. – № 1 – С. 72-80. DOI 10.15588/1607-6761-2018-1-8. 3. Шевченко І.С. Спеціальні питання теорії електропривода. Динаміка синхронного електропривода [Текст] : навч. посіб. / І.С. Шевченко, Д.І. Морозов. – К. : Кафедра, 2014. – 267 с.   CHOICE OF CONTROLLED VARIABLES FOR ENERGY MANAGEMENT SYSTEM OF PISTON СOMPRESSOR UNITS   BOBROV Oleksii Rocket-and-Space Engineering College of Oles Honchar Dnipro National University Ukraine, Dnipro  Introduction. Nowadays on-off control system is common for piston compressors delivery. The control system is applied in case there is no technological need in maintaining the stable pressure level in pneumatic system and there are no dramatic changes of compressed air consumption. Its advantages are described in terms of simplicity of implementation and reliability. The principle of on-off control system operation is based on setting of predetermined pressure limits. Reaching the upper level of pressure the compressor is switched off and it is switched in reaching the lower level. This occurs under the condition of single variable change control (intake pressure) in the system by means of sensor, which is installed. The regular operation of compressed air consumers is provided by means of pneumatic system pressure maintaining in the predetermined range. Purpose statement. The main disadvantage of the system is its negligibility as for the factors influencing the general energy efficiency of «grid – compressor – pneumatic circuit» complex. It does not consider such substantial parameters as losses in power for grid, compressor, and pneumatic circuit. Hence, there is a need in describing the parameters to be changed by control system for losses determining and thus working in the proper regime of their minimizing for maintaining the regular operation of compressed air consumers. Problem solution. To answer the question it is required that we consider the losses in power for various components of the system. The active power losses in electric grid. The losses in asynchronous drive and compressor unit. The losses in the compressed air pipelines. Considering the abovementioned issues, to enable the control system being sensitive to losses in all units of «grid – compressor – pneumatic circuit» system it is need to install:ammeter, А, flow rate meter for compressed air, m3/sec, pressure sensor in the receiver. 

DEVELOPMENT OF AUTOMATIC SPEED CONTROL SYSTEM FOR  SYNCHRONOUS DRIVE OF HIGH-POWER TUMBLING MILLS

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DEVELOPMENT OF AUTOMATIC SPEED CONTROL SYSTEM FOR SYNCHRONOUS DRIVE OF HIGH-POWER TUMBLING MILLS

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