OPTIMIZATION OF STATIONARY AND TRANSITIONAL OPERATING MODES OF THE ELECTRICAL COMPLEX IN METAL PROCESSING LINE

In the electrical complex “induction heater - deforming equipment”, the limiting performance of the complex is the induction heating unit. In this regard, an important task of increasing the effi ciency of the processing complex is to optimize both the design and operating parameters of the induction heating unit. It is shown that the main design parameter infl uencing the energy characteristics of the complex is the length of the heating system. When optimizing the total length of the heater, an iterative model of the process of induction heating of ferromagnetic billets is used. The power distribution algorithm along the length of a two-section heater is a piecewise continuous function. Optimization of the heater length according to the proposed method made it possible to reduce the heater length from 2.8 m to 2.1 m, i.e. by 25%. To search for eff ective control algorithms for non-stationary modes, a refi ned electrothermal model is proposed in the work. It takes into account the nonlinear dependence of the distribution of the power of the sources of internal heat release on the temperature distribution in the metal of the workpieces along the radial and axial coordinates. The problem of fi nding the optimal control of transient modes of a two-section induction heater of methodical action is formulated and solved. The results obtained provide a minimum of energy consumption for heating billets in transient modes under conditions of technological and energy constraints. Variants of starting the heater at various initial temperature states of the load are considered. The results of a comparative analysis of the eff ectiveness of the obtained control algorithms are presented. The structure of the power supply and control system of the induction heating complex is proposed.

The Use of Induction Heating in Assessing the Technical Condition and Operating Intervals in Producing Wells

The paper considers two approaches based on the use of an induction heater: the first is a "large thermal anemometer", in which the casing is heated by induction action and the problem of determining column flows, determining the flow rate and the inflow profile is solved by analyzing the formation of thermal labels (Valiullin et al., 2001, Valiullin et al., 2002), the second is a "small radial-azimuth thermal anemometer - small thermal anemometer", where an induction heater is used to heat the element of the thermal anemometer. In the second case, the problem of estimating the flow direction and estimating the flow rate is solved. For the first approach, "large thermal anemometer", the results of theoretical and experimental studies of the temperature field distribution in a physical model as close as possible to the design of a real oil well, with induction heating of the column taking into account the column flow of liquid. The influence of forced convection on the readings of temperature sensors with different locations in the well (pressed against the inner wall of the column, along the axis of the device) is studied. The advantages of the azimuthal location of temperature sensors when measuring temperature anomalies of the column motion of a liquid are shown. It is established that with the help of an azimuthally distributed temperature probe, it is possible to determine the column flow "from above" when measuring above and below the heating point of the inductor. The optimal time intervals for measuring the temperature at which the allocation of channels for the column movement of the liquid is most effective are determined. For the second approach, "small thermal anemometer", the design features of a borehole thermoconductive indicator of the inflow of indirect heating, which is heated using an induction heater, are considered. Using an induction heater, a uniform heating of the housing of the borehole thermoconductive inflow indicator is achieved. Due to the developed design, the sensor is able to detect the presence of a liquid flow directed perpendicular to the body, and determine the direction of this flow. The "large thermal anemometer" technology has been tested, which has shown its effectiveness and prospects for using it to determine backwater flows (column circulation), but there are still questions related to assessing the effect of thermal convection on the recorded temperature and the possibility of diagnosing the column circulation channel (Valiullin et al., 2017). The article (Valiullin et al., 2008) describes the developed equipment of the "active thermometry" method for conducting geophysical studies of wells, while the classical location of temperature sensors along the axis of the device is used in the borehole probe, which does not make it possible to determine the channels of the circulation channels. The sensors located in this way are more susceptible to the influence of thermal convection, while the change in the velocity and composition of the fluid can be estimated as the presence of circulation channel. In this regard, work was carried out to reduce the influence of convection, the design of the temperature probe was developed, which allows minimizing the influence of thermal convection and increasing the efficiency of the allocation of circulation channel. Thermoanemometers, better known as thermoanemometer sensors (borehole thermoconductive inflow indicator), have been widely used in field geophysics (Zhuvagin et al., 1973). The traditional sensor of a thermal anemometer, with all its advantages, is not without disadvantages, and one of these is the inability to unambiguously determine the presence and direction of the fluid flow directed perpendicular to its body. The solution of this problem would allow, along with the known solved problems, to increase the information content of the thermoanemometer sensor, namely, in terms of detecting the leakiness of the column, evaluating the operating intervals at low debits, the flow direction. This problem is solved in this work on the basis of the use of an indirect induction heater.

Study on Fixed-Point Growth of Thermal Bubble with Micro-Planar Induction Heater

Background: The thermal bubble-driven micro actuators have advantages of simple structure and low working voltage, which have broad prospects in the field of micro-fluidic systems. Methods: This paper presents a new type of micro-planar induction heater which can realize the fixed-point growth of thermal bubbles by adding some active cavities. The micro-planar induction heater is composed of a metal heating plate, a glass substrate and a planar coil. Results: In the experiments, an alternating current of 80kHz was applied to the micro-planar induction heater, both the heating time and the interruption time were 1 s controlled by PLC. A CCD camera was used to record the generation process of thermal bubbles, including nucleation, growth and shrinkage. The experimental results show that thermal bubbles can grow and contract periodically at the position of the cavities when the cavities diameter is 50μm and 90μm, respectively. The ideal thickness of the heating plate is between 6μm and 13μm. Conclusion:: The fixed-point growth of the thermal bubble with a micro-planar induction heater has been studied. This kind fixed-point growth of thermal bubbles can be used in micro actuators such as micro ejectors, micro mixers and micro pumps.