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Homogenization, which is used in the technological schemes of production of most dairy products, is the most energy-intensive of the processes of mechanical processing of milk. One promising way to increase the energy efficiency of homogenization is to use separate homogenization and to use a little-researched stream homogenizer with separate cream feeding. The principle of its action is to pre-divide milk into cream and skim milk, and feed the fat phase with a thin stream into the stream of skim milk. This creates the conditions for achieving the high value of the Weber criterion – the main factor in the dispersion of milk fat. The purpose of these researches is to conduct experimental studies and determine the energy consumption and quality of homogenization of milk after treatment in a stream homogenizer. To achieve this goal, a designed experimental setup was used. The dispersive indices of the milk emulsion were determined by computer analysis of micrographs of milk samples obtained with an optical microscope and a digital camera using Microsoft Office Excel and Microsoft Visual Studio C # software using the OpenCV Sharp library. As a result of experimental studies, the critical value of the Weber criterion for homogenization of milk was determined, which is 28. The regularities of dispersion of milk fat in a stream homogenizer with separate feeding of the fat phase have been established. It is determined that the milk treatment in the experimental homogenizer allows us to achieve an emulsion with an average size of fat globules of about 0.8 μm (at the level of valve homogenizers). The value of the homogenization coefficient is obtained for the disruption of the fat globule in the conditions: subject to a single effect on the emulsion, without the influence of vibration and cavitation. This homogenization coefficient equals 3300 m3/2.s-1.

Homogenization is a necessary process in the production of drinking milk and most dairy products. The specific energy consumption of the most common valve homogenizers reaches 8 kW h.t-1. A promising way to reduce it is the introduction of more effective counter-jet homogenizers. The purpose of these studies is to increase the efficiency of machines of this type through fuller use of their kinetic energy. To achieve this, the design of a ring reflector was developed and experimental studies were carried out to determine its influence on the efficiency of milk fat dispersion in a counter-jet homogenizer. Calculations were made to determine the reflector’s design parameters. An installation for experimental research has been developed, in which the required milk pressure is created with the help of compressed carbon dioxide. The dispersive indices of the milk emulsion were determined by computer analysis of milk sample micrographs obtained with an optical microscope and a digital camera using Microsoft Office Excel and Microsoft Visual Studio C# software using the OpenCV Sharp library. As a result of research, the formula for defining the angle of the reflector top has been determined analytically. Experimental studies proved its validity and allowed determination of the optimal diameter. A comparison of the dependence of the degree of homogenization on the excess pressure in a counter-jet homogenizer proves a 15 – 20% increase in the degree of dispersion when using a reflector. At the same time, specific energy consumption does not increase. Comparison of the distribution curves of milk fat globules by size after counter-jet homogenization and homogenization with a reflector suggests that the average diameter of fat globules for the experimental method decreases from 0.99 to 0.83 μm. This indicates the high quality of the dispersal characteristics of the milk emulsion after processing in a counter-jet homogenizer with a reflector.

The modification of rotor-pulsation machine – pulsation machine with a vibrating rotor (PM with VR) has been researched in the work. Rotor in such modification not only rotates but also oscillates axially with the frequency about 3000 min-1 and amplitude 0,5–1,0 mm. The aim of this research was to define specific features of milk homogenization process in PM with VR and disperse characteristics of milk emulsion. Analytical researches resulted in finding dependence of milk emulsion acceleration as a main factor of milk fat particles breakup subject to the design and kinematic parameters of PM with VR. Experimental researches were carried out on the laboratory setup of the pulsation machine with a vibrating rotor which was designed by the authors. The subject of experimental researches is cow's milk. The sizes of milk fat globules after homogenization were measured by the optical microscope equipped with a digital camera. The researches resulted in defining characteristics of milk emulsion dispersing in PM with VR. Thus acceleration grows when diameter, oscillation amplitude and rotation frequency of the rotor are increased, and channels length of the rotor and stator, the gap between them are decreased and the number of rotor openings is 4 or less. Empirical dependence between the average diameter of the fat globule (0,7–1,9 μm) and the average emulsion acceleration ((1–10)·103 m/s2) in the interrupter of PM with VR is defined which proves that the emulsion flow acceleration is the main cause of homogenization of PM with VR with 92 % confidence. High quality of the milk emulsion after processing in PM with VR has been proved. The crankshaft rotation frequencies up to 2880 rpm and rotor oscillation amplitude of 1 mm enable to receive milk emulsion with the average dispersion about 0,8 μm that corroborates using PM with VR in the industrial conditions for milk homogenization to be perspective.

Дослiджено фiзико-хiмiчнi властивостi продуктiв вуглецевотермiчного вiдновлення оксидної хромвмiсної рудної сировини. Це необхiдно для визначення параметрiв, що знижують втрати Cr при переробцi рудних матерiалiв i використаннi металiзованих хромвмiсних легуючих добавок у сталеплавильному виробництвi. Визначено, що пiдвищення температури обробки з 1250 K до 1450 K призвело до збiльшення прояву Cr 23 C 6 та (Cr, Fe) 7 C 3. При цьому дифракцiйнi максимуми Cr 2 O 3 вiдповiдали тенденцiї послаблення та пiсля обробки при 1450 K мали залишковий характер. Cr 3 C 2 на дифрактограмах провялявся лише пiсля обробки при 1250 K. Фаза металевого Cr прослiдковувалась в зразках пiсля обробки при 1350 K та 1450 K з пiдсиленням iнтенсивностi прояву при збiльшеннi температури нагрiвання. Визначено, що мiкроструктура продуктiв вiдновлення неоднорiдна з присутнiстю часток рiзного розмiру та хiмiчного складу. З пiдвищенням температури вiдновлення з 1250 K до 1350 K та 1450 K i розвитком вiдновних процесiв мало мiсце спiкання часток з утворенням губчастої мiкроструктури. Виявлено дiлянки, що характеризували включення i фази iз вмiстом Cr до 65,10 % мас., Fe-до 16,13 % мас. Також виявлено окремi локальнi дiлянки з частками з вiдносно високим вмiстом рудних домiшок та вуглецю. З отриманих результатiв дослiдження витiкає, що найбiльш прийнятною температурою для вiдновлення є 1450 K. В цьому випадку забезпечується вiдновлення з переважанням у фазовому складi Cr металевого та карбiдiв (Fe, Cr) 7 C 3 i Cr 23 C 6 вiдносно оксидної складової Cr 2 O 3. При цьому менший залишковий вмiст вуглецю обумовлений бiльш високою ефективнiстю дiї вiдновника порiвняно з iншими температурними режимами. Завдяки губчастiй мiкроструктурi стає можливим бiльш швидке розчинення, порiвняно iз стандартними феросплавами, при цьому реалiзується скорочення часу виплавки Ключовi слова: хромвмiсна оксидна рудна сировина, фазовий аналiз, вуглецевотермiя, карбiд, легування, вiдновлення

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