No abstract

The extrusion process of oil-containing raw materials using a twin-screw extruder is becoming increasingly common in food technology. The problem of high energy costs for the implementation of this process is solved by reducing the resistance of the process mass due to the preliminary grinding of raw materials. The classical theory of extrusion is based mainly on the use of theoretical solutions of mathematical models of processes, which are simplified and allow determining integral parameters using coefficients, the preparation of which for the calculation of the corresponding processes and equipment is a rather complicated and approximate procedure. Mathematical modelling of the movement of the technological medium at the individual stages of the processing of raw materials allows us to determine the analytical dependences for the power and energy parameters of the system and to carry out their effective technical and economic evaluation. Using the methods of mathematical analysis and data processing in the MathCAD software environment, graphical dependences of the power and energy parameters of the research technical system were obtained. By increasing the density of the oil-containing raw materials, which is extruded in the research extruder by 40.5% the pressure force increases by 41%, that is, there is an almost proportional relationship between the pressure force and the density of the processed raw material. With an increase in the angular velocity of the drive shaft ω more than 8 rad.s-1, the pressure force in the research process increases sharply. With an increase in the density of raw materials, it is grinded before extrusion by 40%, the power consumption for the grinding process increases by 2.8 times for the recommended operating mode. Energy losses for pressing completely grinded raw materials are reduced by 2.52 times.

The analysis of constructive-technological schemes of vibrating conveyor machines for heat-exchange processing of bulk technological masses in the current mode is carried out, which allowed to substantiate the effectiveness of using a new modification of infrared dryers of vibration-wave execution with a flexible transporting body. For this scheme, a vibrating system is developed which mathematical modelling allowed to determine and substantiate the main parameters of the operating mode of the drive mechanism of the projected device. The experiments, using the developed research model, confirm and refine the results of theoretical analysis, energy efficiency and comparatively low metal consumption of the design structure. The difficulty of working with such a large number of factors led to the application of the second similarity theorem and the introduction of a mathematical model of the criteria of Stanton, Froude, Burdo, whose magnitudes are reflected through the main factors of influence and were found experimentally. After using the "dimension theory" and graph-analytic analysis of power functions, a criterial equation of the investigated process was obtained. This allows recommending the regime parameters and the design series of projected thermo-radiation dryers with vibration-wave transport of products when varying the main factors of influence.

In modern economic conditions, the chosen technology of raw material processing and the choice of the necessary equipment for both the line as a whole and the oil press are of great importance in oil production. In small-capacity workshops, screw presses of various designs are used. The twin-screw extruder occupied a certain niche among the press equipment with a productivity of 150–500 kg/h. Their use can significantly simplify the technology of oilseed processing. They combine operations of heat treatment, grinding, and pressing of vegetable oil. It is important to study the influence of geometric parameters of the oil pressure path and screw nozzle on the oil yield. In twin-screw extruders, it is rational to choose the pitch of the worm, the width of the channel between the turns, the width of the crest of the turn and the length of the nozzle with variable geometrical parameters. The analysis and selection of geometrical parameters of working bodies of a twin-screw extruder on the basis of theoretical calculations are carried out. Two sets of experimental working bodies with the changed geometrical parameters are made. Their theoretical degree of compression is determined, which is 5.50, 4.69, and 4.33, respectively. It is experimentally confirmed that the oil yield depends on the degree of compression due to the geometric parameters of the screw. The effect of a sharp drop in the free volume of the screw on the energy performance and press extruder performance has been revealed. The general nature of the change in the free volume in the areas of nozzle groups is accompanied by an uneven decrease of 40–80% towards the release of oil cake. The nature of the change in the free volume of turns along the length of the screw shaft characterizes the correctness of its design. The selection of rational geometric parameters of the working bodies should be considered in combination with other design parameters, which will intensify the process of oil pressing.

Centrifugal and vibrational technological effects are among the main approaches to intensify the process of plant raw materials hydrolysis for pectin extraction. With the impulse intensification of such a process, it is possible not only to increase its efficiency, but also to achieve the compactness of the equipment, reduce the cost of electricity and improve the quality of the product of hydrolysis. The hypothesis is confirmed, according to which the vibro-centrifugal intensification of hydrolysis increases the driving force of the process by not only activating the material flows of raw materials and reagents, but also by reducing the resistance in the technological environment. Graphical and analytical dependencies of the power and energy parameters of the oscillatory system were obtained, which proved the overcoming of the flow resistance of the liquid medium in the entire speed range of the drive shaft with the potential to intensify the process at a power consumption of 2.0 – 3.0 kW and or by the force of 2.3 – 2.5 kN using the Lagrange and Cauchy methods for composing and solving the equations of motion of the moving components of the tested hydrolyser with vibrating activators, and the methods of mathematical analysis and their processing in the MathCAD. The analysis of the presented parameters of the studied process of mixing the pectin-containing mass in the hydrolyser allowed us to determine the rational mode parameters of processing, which correspond to the angular velocity of the drive shaft  rad/s at the power consumption of 500 – 600 watts.