MULTI-CHAMBER MICROWAVE - CONVECTIVE DRYER OF CEREALS

ABSTRACT

The article discusses the scheme of the developed multi-chamber combined convective drying unit based on electromagnetic technology using a stepped mode of the electromagnetic field of ultra high frequency.

АННОТАЦИЯ

В статье рассмотрена схема разработанной многокамерной комбинированной конвективной сушильной установки на основе электромагнитной технологии с использованием ступенчатого режима электромагнитного поля сверхвысокой частоты.

Keywords: stepped mode, combined, ultra-high, frequency, multi-chamber, convective, dryer, electromagnetic fields.

Ключевые слова: ступенчатый режим, комбинированный, сверхвысокий, частота, многокамерный, конвективный, сушильная установка, электромагнитная поля.

The use of a stepwise mode of combined ultra high frequency (UHF) -convective drying was reflected in the developed multi-chamber cereal dryer [1].

A multi-chamber combined ultra high frequency (UHF) - convective dryer is shown in Fig. 1. Ensuring the stepwise mode in the installation of the drying chamber is shown in Fig.2.

Figure 1. Multi-chamber combined ultra high frequency (UHF) - convective dryer

A multi-chamber combined ultra high frequency (UHF) oven is a convective drying plant, which is made in the form of a housing 1, made in the form of a cylinder or a prism. It is located coaxially with a blocking tank 2, repeating the shape of the body, and dividing it into a central and peripheral zones, and the central zone performs the function of a hopper 3 with a bottom 4, and a drying chamber is located in the peripheral zone, consisting of separate sections 5 and alternating screw conveyors 6. Each drying section is equipped with perforated gratings 7, lower boot 8 and upper overflow 9 windows. The body is equipped with loading 10 and unloading 11 sluice gates, a branch pipe 12 for supplying a drying agent and a branch pipe 13 for outlet. The drying agent (air) is distributed to individual sections 5 through the air distribution chamber 14, the annular manifold 15 and the valves 16. Screw conveyors are driven by a motor-reducer 17, a bevel gear pair 18, sprockets 19 and valuable gear 20. An insert 21 is coaxially installed in the partitionable container 2, with magnetrons 22 placed in it, other magnetrons 23 are installed on the inner side of the container opposite the individual sections of the drying chamber. The ultra high frequency (UHF) generator 24 is installed on the conical cover of the blocking tank 2 (The designs of the ultra high frequency (UHF) generator and magnetrons are not disclosed in the application materials due to their well-known nature).

Figure 2. Device for providing stepwise mode of combined microwave drying

In order to avoid screening of ultra high frequency (UHF) waves, the body 1, the blocking container 2, the screw conveyors 6 and the insert 21 are made of a dielectric material, for example, fiberglass.

Consider the operation of a drying plant using the example of drying mung bean grains (a Central Asian legume).

Moistened grains evenly through the loading sluice gate 10 enters the first drying section 5 in the direction of material movement, under the perforated grate 7 of which the drying agent (air) is supplied through the valve 16, which enters the annular collector 15. At the same time, the ultra high frequency (UHF) generator 24 is turned on, which initially feeds the magnetrons 23. Under the influence of the upward flow, a fluidized layer of material is formed, which is dried due to microwave generation. The material dried to a certain moisture content from the first section enters through the loading window 8 into the screw conveyor 6 following it in the direction of movement of the material, powered by a motor-reducer 17 and rises. When lifting, the partially heated material does not come into contact with air (heat carrier) and, identical to the oscillating drying mode, rests while moving in the closed space of the screw conveyor. This ensures the movement of moisture from the deep layers to the surface of the material at t=30-32⁰C.

Then the material through the overflow window 9 enters the next drying section 5, where it is also dried in a fluidized bed with superimposed microwave generation. Thus, the material to be dried is repeatedly dried in a suspended bed and rested in a screw conveyor according to a sequentially stepped cycle of operation and simultaneous exposure to microwave waves. From the latter in the direction of movement of the material of the screw conveyor 6, the dried material with a temperature of t=52-53⁰C enters the hopper 3, where it is dried due to the additional inclusion of magnetrons 22 to the standard humidity.

Exhaust air saturated with evaporated moisture is removed through pipe 13. As the material dries, its frostiness increases and the height of the fluidized bed increases from section to section. Therefore, at a given performance of the apparatus, the loading windows 8 of the screw conveyors 6 are provided at different heights. The height of the fluidized bed for different materials is controlled by the flow rate of the drying agent through valves 16. The temperature regime of drying by zones is controlled by the duration of exposure to microwave waves and their power [2].

The use of microwave electromagnetic fields allowed:

• improve thermal efficiency;
• to intensify the drying process by obtaining an ultra-high generation system.

The introduction of electromagnetic technology will improve the quality of the grain and increase the shelf life.

References:

1. Н.Ф. Ушакова, Опыт применения СВЧ энергии при производстве пищевых продуктов [Текст] / Н.Ф. Ушакова, Т.С. Копысова, А.Г. Кудряшова, В.В. Касаткин // Пищевая промышленность. – 2013. - №10 – с 30-32.
2. И.К. Колесников, А.А. Саитов. Устройство экстрагирования растительного сырья на основе электромагнитных технологий. “АГРО ИЛМ” илмий амалий журнали 2019 йил 4-сони. 115-116 бет.
3. И.К. Колесников, А.А. Саитов. Электромагнитная технология переработки растительного сырья. “АГРО ИЛМ” илмий амалий журнали 2019 йил 6-сони. 112-113 бет.
4. Абиев, Р.Ш. Моделирование процесса экстрагирования из капиллярно-пористой частицы с бидисперсной структурой / Р.Ш. Абиев, Г.М. Островский // Теорет. основы хим. технологии. - 2001. - Т. 35. № 3. - С. 270.
5. Бабенко Ю.И. Экстрагирование растворенного вещества из пористого тела в движущуюся жидкость / Ю.И. Бабенко, Е.В. Иванов // Теор. основы хим. технол. - 2007. - Т. 41, № 2. - С. 225-227.
6. Борисенко, Г.Г. Использование гидродинамической неустойчивости при микроволновом облучении жидких сред в биохимическом эксперименте / Г. Г. Борисенко, И.Г. Полников, К. Д. Казаринов // Электронная техника. Сер. 1. Электроника СВЧ. - 2007. - № 1(489). - С. 98-106.