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- Title
ДОСЛІДЖЕННЯ КРОХМАЛЬНОЇ ПАТОКИ ЯК ОБ′ЄКТУ РОЗ-ПИЛЮВАЛЬНОГО СУШІННЯ В СИСТЕМІ «КРАПЛЯ-ПАРОГАЗОВЕ СЕРЕДОВИЩЕ».
- Authors
Т. Я., Турчина; Е. К., Жукотський; Г. В., Декуша; А. А., Макаренко
- Abstract
An article is devoted to the study of maltodextrin as an object of spray drying in the system "dropvapor medium" at an experimental apparatus for drying single droplets in a flow of heat transfer agent. Liquid maltodextrin concentrate containing 78-83% dry matter is characterized by a high-viscosity consistency, which causes complications in many technological processes. Obtaining it in the dry powder form by spraying will improve its conditions of use and expand its application. The presence of sugary substances, which are present in mildly acidic solutions, сontributes to the manifestation of properties typical for amorphous substances and polymeric materials. This is the reason why maltodextrin belongs to the category of thermoplastic materials which are ones of the most difficult spray drying objects. The drying ability of the maltodextrin coloid system as well as the adhesion of the dried particles in the spray dryer chamber are inherent in its physicochemical characteristics and rheological properties. It is they that determine the kinetics of drying droplets of the solutions, morphology and strength of the dried particles under the influence of different temperature parameters. Studies of drying droplets of maltodextrin solutions having a mass fraction of reducing sugars of 38-42% were carried out at concentrations of 40%, 45%, 50%, 55% and 60% of dry matter and heat transfer agent temperatures of 140°C, 160°C, 180°C and 200°C. It has been determined that when the solutions are ≥ 50% dry matter and the heat transfer agent temperatures rises to 200°C, an instant increase in the concentration and pressure gradients on the surface of the dense impermeable shell of the hanging drop occurs which is typical for coloid systems. These facts are evidenced by the photographic materials of various changes in the shape, size and structure of droplets in the stages of boiling and drying. Moreover, a sharp increase in diffusion resistance to moisture transfer results in the retention of residual moisture inside the droplet. This fact is confirmed by boiling of water vapor in the form of bubbles which emerged from the holes of the drops during their probing in the flow of heat transfer agent. It was recorded when studying the physical state of dried droplets (particles) of the solutions (≥50%). A higher capacity to dry to a dry state, which was determined from the kinetic dependences of the relative duration of droplets dehydration to the critical point 3, was found for solutions with a concentration of <50% at heat transfer agent temperature of 180-190oС. However, the dried droplets of any of investigated maltodextrin solutions in the flow of heat transfer agent were in a viscous-plastic state and revealed adhesion. An analysis of the physical state of dried drops of maltodextrin in the flow of the heat transfer agent and beyond its boundaries allowed to establish that only after cooling did the particles become solid without adhesion properties (20°С).
- Subjects
DRYING apparatus; AMORPHOUS substances; HEAT transfer; MALTODEXTRIN; SPRAY drying
- Publication
Scientific Works, 2021, Vol 85, Issue 2, p91
- ISSN
2073-8730
- Publication type
Article
- DOI
10.15673/swonaft.v2i84.1879