RU2338977C1 - Method of moisture removal in vacuum - Google Patents

Abstract

FIELD: physics; heating.

SUBSTANCE: in common method of moisture removal in vacuum including evacuation 0.1-10 Pa, raw materials heating, moisture removal and condensation and raw materials agitation, in case of film boiling temperature near to top cover of evaporator chamber is lowered to 16-22°C. After foam is removed, temperature is raised to initial value. Operation is repeated if required.

EFFECT: higher method efficiency due to suppression of film boiling.

Description

The invention relates to apparatuses of the food industry, and in particular to a technology for concentrating liquid and obtaining dry food products by evaporating and drying them in a vacuum, and can be applied in small enterprises and farms devoid of steam supply.

A known method of condensation of water vapor from a drying device in a fluid flowing through a vacuum pump [1]. However, this method does not provide measures to suppress the foaming that occurs when heated, and does not allow to achieve a vacuum of 0.1-10 Pa, providing high performance removal of free moisture at temperatures of 30-50 ° C, allowing to maintain the biological activity of the final product.

The closest technical solution, selected as a prototype, is the method implemented by the installation for removing moisture, including the operation of creating a vacuum of 0.1-10 Pa, heating the raw materials, removing and condensing moisture and mixing the dried raw materials [2].

However, at the stage of heating the liquid when film boiling occurs, foam may enter the steam line and condensate collector, which significantly reduces the performance of the evaporation process, up to its complete stop.

The problem to which the invention is directed, is to increase the efficiency of the method by suppressing film boiling that occurs at the stage of heating the evaporated product.

This is achieved by the fact that in the known method of removing moisture in a vacuum, including creating a vacuum of 0.1-10 Pa, heating the raw materials, removing and condensing moisture and mixing the raw materials, when film boiling occurs, the temperature near the top cover of the evaporator chamber is reduced to 16-22 ° C, after suppressing the foam, the temperature is raised to the initial value, if necessary, the operation is repeated.

The introduction of the operation of lowering the temperature near the top cover of the evaporator chamber to 16-22 ° C creates a zone of lower temperature at the outlet of the evaporator, which leads to condensation of moisture in the upper layers of the film, a decrease in the size of the bubbles and a reduction in foaming.

After the suppression of film boiling, an increase in temperature near the upper cover of the evaporator to the initial value allows one to enter the established mode of free moisture removal and carry out the evaporation process.

The repetition of these operations is associated with the need to suppress the newly emerged film boiling with increasing temperature in the region of the upper evaporator cap.

The method of removing moisture in vacuum is as follows. The dried raw material is loaded into the evaporator, a vacuum of 0.1-10 Pa is created in the system and the temperature in the evaporator is increased. When film boiling occurs, the temperature near the top cover of the evaporator chamber is reduced to 16-22 ° C. Lowering the temperature inhibits foaming. After eliminating film boiling, the temperature near the top cover of the evaporator chamber is raised to its initial value. In case of foaming growth, the above operations are repeated until the evaporation process returns to steady state.

Tests conducted on animal blood. During the tests, a small-sized vacuum evaporation unit was used [2]. An annular tubular reflux condenser was mounted on the inner surface of the upper cover of the evaporator chamber. Coolant was supplied to the reflux condenser, with the help of which the temperature at the outlet of the evaporator was reduced. Using a foreline pump, the vacuum in the system was maintained at ~ 10 Pa. Blood heating was accompanied by profuse foaming. When the foam approached the top cover of the evaporator, coolant was supplied to the reflux condenser at a temperature of 18 ° C. The appearance of a zone of lower temperature in the upper part of the evaporator led to condensation of moisture in the rising foam and was accompanied by its suppression. As a result of three times connecting and disconnecting the reflux condenser, the evaporation process went into stationary mode.

This method allows to increase the efficiency of the known method by suppressing film boiling that occurs at the stage of heating the evaporated product.

Information sources

1. Application EPO No. 0240793, cl. F26B 7/00, 1989.

2. Patent RU No. 2276314, cl. F26B 19/00, F26B 5/04, 2006 - prototype.

Claims (1)

A method of removing moisture in a vacuum, including creating a vacuum of 0.1-10 Pa, heating the raw materials, removing and condensing moisture and mixing the raw materials, characterized in that when film boiling occurs, lower the temperature near the top cover of the evaporator chamber to 16-22 ° C, after suppressing foam, the temperature is raised to the initial value, if necessary, repeat the operation.