RU2490569C2 - Method to dry pine cones - Google Patents

Abstract

FIELD: heating.

SUBSTANCE: method to dry pine cones includes cleaning, sorting, charging of cones into perforated containers, installation into a chamber, drying of cones at lower temperature in warm air flow. After charging into perforated containers, low-temperature drying of cones is carried out in a microwave field with frequency of 2450 MHz due to volume heating of the entire massif of cones in a vacuum-microwave chamber, without preliminary stage of cone moisture balancing, at pressure reduced down to the value that limits the drying temperature (moisture evaporation) at the safe level for seeds, available in cones. At the same time drying of cones may be carried out in a rotary perforated drum, which improves evenness of microwave heating and drying of cones.

EFFECT: invention should exclude steaming of seeds and make it possible to perform the process with high speed with no damage to seeds quality.

2 cl

Description

The invention relates to the technology of forest seed production, namely, drying cones of conifers for the purpose of further extraction of seeds from them, intended for growing seedlings of trees.

A known method of convective drying of pine and spruce cones, selected as a prototype, which consists in the fact that the cones after cleaning and sorting by size, laid in mesh boxes are installed in the chamber and are dried in a mild mode at a temperature of not more than 41 ... 45 ° C a circulating stream of warm air, the temperature of which does not exceed 54 ° C, according to the program, which first provides for the obligatory leveling of the humidity of the cones to 25% for 2 hours, and then drying. The total drying time is quite large and is 18 ... 19 hours. (I.A. Markova. Current problems of forest cultivation. A manual for students, undergraduates and graduate students of the specialty 250201 - "Forestry", St. Petersburg, 2008, pp.21-22).

The reasons that impede the achievement of the result indicated below include the fact that with convective technology, in which the object is heated through its surface, a substantial reduction in the drying time of cones in soft conditions is fundamentally impossible, and even a slight increase in the temperature of convective drying of cones will inevitably lead to a decrease in quality seeds with their loss of germination.

The disadvantages of this method also include the need to use sufficiently complex automation devices (sensors, control equipment, actuators) to implement mild cones dehydration modes.

The technical result achieved by the application of the proposed method is to provide a radical acceleration of the drying process of cones due to their uniform volumetric microwave heating to achieve a reduction in drying time of 10 ... 15 times, eliminating the need for a special technological transition "equalization of moisture cones" in the first stage of drying, simplification of solving the problem of ensuring a given low drying temperature. To maintain the set drying temperature, it is sufficient to provide the set value of the reduced pressure in the drying chamber during the microwave heating period.

The use of microwave heating eliminates the need for moisture equalization operation due to the fact that the intensity of heating and, accordingly, dehydration of cones with different humidity in the microwave field is higher for more humid cones, which ensures moisture equalization in the initial period of the drying process.

The technical result in the implementation of the invention is achieved by the fact that in the known method of drying the cones, including cleaning, sorting the cones, loading into a perforated container, installing in a chamber, pre-drying with equalizing the humidity of the cones to a predetermined value in a stream of warm air, drying the cones at a low temperature in the flow of warm air, the peculiarity is that, after loading into a perforated container, low-temperature drying is carried out in a microwave field with a frequency of 2450 MHz due to volumetric heating of the entire array cones in a vacuum-microwave chamber without a preliminary stage of equalizing the moisture of the cones, at a pressure reduced to a value that limits the drying temperature (evaporation of moisture) to a level safe for seeds in the cones.

For example, drying pine cones should be carried out at a temperature not higher than 41 ... 45 ° C, to ensure that the pressure in the chamber should be set and maintained during the entire processing process no more than 60 ... 70 mm Hg.

The proposed method of drying cones of conifers is as follows.

Cones after cleaning and sorting by size are loaded into a perforated radio-transparent container, namely in a perforated drum, and installed in a vacuum-microwave chamber. In the working volume of the chamber, a vacuum ring is created, and then maintained during the process, the vacuum is at a level specified by the technology, the value of which is determined based on the set allowable drying temperature. Volumetric heating and drying of the array of cones is carried out with their continuous mixing in a rotating perforated drum with microwave radiation at a frequency of 2450 MHz. The drying time is determined by the power of the microwave radiation source and the initial moisture content of the cones.

Information sources

I.A. Markov. Modern problems of forest cultivation. Textbook for students, undergraduates and graduate students of the specialty 250201 - "Forestry", St. Petersburg, 2008, pp.21-22.

Claims (2)

1. A method of drying cones of coniferous trees, including cleaning, sorting, loading cones into a perforated container, installing in a chamber, drying cones at a low temperature in a stream of warm air, characterized in that after loading into a perforated container low-temperature drying of cones is carried out in the microwave field frequency of 2450 MHz due to volumetric heating of the entire array of cones in a vacuum-microwave chamber without a preliminary stage of equalizing the moisture cones at a pressure reduced to a value that limits the drying temperature ( evaporation of moisture) at a level safe for seeds in cones. 2. The method according to claim 1, characterized in that the drying of the cones is carried out in a rotating perforated drum, which improves the uniformity of microwave heating and drying of the cones.