RU2202168C2 - Grain and seed drying method - Google Patents

Abstract

FIELD: agriculture. SUBSTANCE: method involves active layer-by- layer ventilation of grain with air-and-ozone mixture having ozone concentration of from 1 mg/cu.m to 30 mg/cu.m and relative humidity of at least 75-80%. Thickness of first layer is determined from formula: h₁ = A•W^-3,7•C^0,2•V^0,8, of second and subsequent layers from formula: h₂ = A₁•W^-3,7•C^0,2•V^0,8, where W is basic moisture content of grain, %; C is concentration of ozone in mixture, mg/cu. cm; V is speed of air-and-ozone mixture in layer, m/s, with A and A₁ being coefficients used for wheat grain A=

, for barley grain A=

, and for oats grain A=28,5•10⁴ and A₁ = 26,9•10⁴. Method allows grain drying intensity to be increased by 1.3-1.6 times depending upon kind of cereal crop. EFFECT: increased efficiency, reduced volume of grain storage, and reduced consumption of heat power for drying process. 5 dwg, 3 ex

Description

 The invention relates to methods for drying grain and seeds of grain, leguminous and cereal crops by active ventilation in a granary with a gradual increase in the height of the embankment and can be used in agriculture, the food industry, the bakery system and related industries.

 A known method of drying grain by active ventilation with external or slightly heated air with layer-by-layer laying of the material [1], in which the thickness of the grain layer is continuously increased at a speed equal to the speed of movement of the drying zone. The disadvantage of this method is the complexity of its implementation and the low speed of movement of the drying front.

 A known method of drying by active ventilation with periodic layer-by-layer loading of grain into the granary as the surface humidity of the previous layer decreases, moreover, active ventilation is carried out with air with relative humidity up to 60 ... 65%, and the thickness of the first and subsequent layers is determined by the dependences, including the initial grain moisture [2]. This method is the closest to the claimed and selected for the prototype.

 However, this method has several disadvantages, the main of which are: relatively low thicknesses of the first and subsequent layers of grain, especially when its moisture is high, a limited amount of relative humidity of the air supplied to the layer, which leads to a low intensity of the process.

The objective of the invention is to increase the intensity of the drying process and reduce energy costs. This is achieved by the fact that in the drying method by active ventilation with periodic layer-by-layer filling as the moisture content of the surface of the previous layer begins to decrease, active grain ventilation is carried out with an ozone-air mixture with an ozone concentration of up to 30 mg / m ³ and a relative humidity of 75 ... 80 %, and the thickness of the first layer is determined by the formula h ₁ = A • W ^-3.7 • C ^0.2 • V ^0.8 , the second and subsequent layers by the formula h ₂ = A ₁ • W ^-3.7 • C ^{0 , 2} • V ^0.8 , where A and A ₁ are coefficients; C is the concentration of ozone in the mixture, mg / m ³ ; V is the air velocity, m / s; W is the initial moisture content of the grain,%. For wheat grains A = 23.3 • 10 ⁴ and A ₁ = 21.3 • 10 ⁴ , for barley grains A = 26.8 • 10 ⁴ and A ₁ = 24.3 • 10 ⁴ , for oat grains A = 28 , 5 • 10 ⁴ and A ₁ = 26.9 • 10 ⁴ .

New is the use for ventilating an ozone-air mixture with an ozone concentration of up to 30 mg / m ³ and relative humidity up to 75 ... 80% of the formula for calculating the thickness of the first and subsequent layers of grain loaded sequentially into the storage.

 Thus, the claimed method meets the criterion of "novelty."

 The invention meets the criterion of "inventive step", as a result is achieved that satisfies the corresponding need, namely, increasing the intensity of the drying process.

 The invention is also "industrially applicable", as it can be used in agriculture for drying grain.

The use of an ozone-air mixture is known [3], but for a one-time loaded grain layer, and the drying efficiency for periodic layer-by-layer filling of the storage is low by this method: in case of insufficient layer thickness, the grain is quickly saturated with ozone and the ozone-air mixture enters the atmosphere with an ozone concentration in a mixture close to the original, in the case of an increased layer thickness, the ozone-air mixture is worked out, but the drying process is slowed down, which leads to damage to the upper layer of grain, in addition, the ozone concentration is not pre exceeds 20 mg / m ³ .

 The invention is illustrated by drawings.

 In FIG. 1 shows graphs of the choice of layer thickness depending on the moisture content of wheat, barley and oats. Curves 1, 3, 5, and 7 refer to loading the first layer; curves 2, 4, 6, and 8 — to the loading of subsequent layers, with curves 3 and 4 obtained for purging the layers with outside air, the rest with an ozone-air mixture.

The drying conditions in figure 1: the concentration of ozone in the layer C = 10 mg / m ³ ; the velocity of the gas mixture in the grain layer V = 0.1 m / s; relative humidity of the gas mixture φ≤75. . . 80%, under these conditions, the beginning of a decrease in the moisture content of the grain surface will occur in no more than 6 hours, which will ensure high-quality drying.

 In FIG. Figure 2 presents the logarithmic coordinates of the graphs of changes in the drying rate of grain N versus the concentration of ozone C in the ozone-air mixture, curves 1, 2, and 3 relate to wheat, barley, and oats, respectively.

 In FIG. Figure 3 shows the logarithmic coordinates of the graph of the change in the drying rate of grain N versus the relative humidity φ of the gas mixture. Curves 1 and 2 refer to barley and wheat grains, respectively, when purged with an ozone-air mixture, and curves 3 and 4, to barley and wheat grains when purged with outside air.

The drying method is as follows. Pre-cleaned wet grain is fed by floor mechanization (conveyor belts, loaders, etc.) to the storage and distributed evenly on the floor, which is equipped with a system of air distribution channels connected to the fan and air heater. The thickness of the first layer of grain loaded in one go is determined by the formula h ₁ = A • W ^-3.7 • C ^0.2 • V ^0.8 , m; when detecting a decrease in humidity on the surface of the first layer, the next grain layer is loaded, the thickness of which, like the subsequent layers loaded in one go, is determined by the formula h ₂ = A ₁ • W ^-3.7 • С ^0.2 • V ^{0, 8} , where for wheat A = 23.3 • 10 ⁴ and A ₁ = 21.3 • 10 ⁴ ; for barley, A = 26.8 • 10 ⁴ and A ₁ = 24.3 • 10 ⁴ ; for oats, A = 28.5 • 10 ⁴ and A ₁ = 26.9 • 10 ⁴ .

Drying of grain by active ventilation at an air speed in the layer of 0.1 ... 0.25 m / s for layered storage is widely used in agriculture, its main advantage is the low cost of energy and living labor for the maintenance of drying equipment. However, in central Russia, precipitation often occurs during the harvest season, which limits the possibility of ventilating the grain with outside air, since the relative humidity significantly exceeds 60 ... 65%, which is the limit for drying the grain to normal humidity without risk of spoilage. Heated air at 4 ... 6 ^o C allows you to reduce its relative humidity by 20 ... 30% and ventilate, however, this significantly increases the cost of energy for drying at a relatively low process intensity, which does not exclude the possibility of damage to grain or seeds.

A higher degree of air heating (6 ... 10 ^o C) intensifies the drying process, but leads to increased energy costs and drying out the lower layer of grain, which is undesirable during storage.

 The saturation of air with ozone allows both to increase its moisture-absorbing ability and to intensify the drying process of grain by accelerating the migration of moisture in the caryopsis when ozone decays with the release of heat. This ensures the intensification of the drying process due to the increased moisture absorption capacity of the ozone-air mixture, as well as the possibility of using outside air with a higher relative humidity, i.e. dispense with its heating or with a lower degree of heating, which reduces the energy consumption for drying. Additional energy costs for ozone synthesis do not exceed 2 kW • h / kg ozone and can be neglected.

Example 1. Dried moistened to 16, 19, 24, 28 and 33% grain of wheat, barley and oats in the cassette of the laboratory setup at a speed of ozone-air mixture V = 0.10 m / s, ozone concentration 10 mg / m ³ , temperature 26 ^o C for 6 hours. In this case, the position of the upper boundary of the drying front, which moved to a height of h _{1, was} examined (the exposure of 6 hours was selected based on recommendation [1] on the conditions for safe drying of seeds in storages with layer-by-layer loading). Then, the excess grain sample with a thickness exceeding h ₁ was removed, and fresh material was added to the cassette and again purged under similar conditions for 6 hours, fixing the position of the upper boundary of the drying front, i.e., the thickness h ₂ , etc. The obtained values of h ₁ and h _{2 were} connected by curves (Fig. 1).

Example 2. Dried moistened to 19% grain of wheat, barley and oats in a laboratory cassette with a layer of h = 0.3 m ozone-air mixture with an ozone concentration of from 1 to 30 mg / m ³ at a temperature of 26 ^o C to a moisture content of 16. ..17% and determined the drying rate N. The obtained dependencies in the coordinates N ~ C are shown in figure 2. An increase in N was established with an increase in ozone C concentration up to 30 mg / m ³ , and at C≥30 mg / m ^3, the grain drying speed does not depend on the concentration value, and the drying rate N does not depend on C concentration at C≤2 mg / m ³ (figure 2).

Example 3. Dried moistened to 19% grain of barley and wheat to a moisture content of 16 ... 17% ozone-air mixture with a concentration of C = 10 mg / m ³ in a layer 0.3 m thick, the temperature of the coolant was 25 ... 26 ^o C, and the relative humidity of the mixture was varied in the range from 35 to 90% (by moistening the coolant).

 A smooth decrease in N was established with an increase in the values of φ> 75 ... 80%. In the case of drying the grain with non-zoned air, a steep drop in N was established at φ> 60 ... 65% (Fig. 3).

 It has been established that due to the higher moisture absorption capacity of the ozone-air mixture, the N value decreases rapidly not at φ = 60 ... 65%, but at φ = 75 ... 80%, which significantly expands the possibility of drying grain with an unheated ozone-air mixture.

Using the proposed drying method allows you to:
- increase the intensity of the drying process in 1.3 ... 1.6 times depending on the grain culture;
- Up to 2 times increase the capacity of the grain storage;
- reduce by 20 ... 40% the specific heat consumption for drying.

Sources of information
1. Berzinsh E. R. Productivity and energy performance of drying by active ventilation with layer-by-layer stacking of grain. Proceedings of the Latvian Agricultural Academy, 1979, no. 159, p. 13-22.

 2. RU 2016504 C1, 07/30/1994.

 3. SU 1095899 A, 06/07/1984.

Claims (1)

A method of drying grain and seeds, including active ventilation within the storehouse, with periodic layer-by-layer filling of the storehouse as the moisture content of the material begins to decrease on the surface of the previous layer, characterized in that the grain is ventilated with an ozone-air mixture with an ozone concentration of from 1 to 30 mg / m ³ and relative humidity not less than 75-80%, while the thickness of the first layer is determined by the formula h ₁ = A • W ^-3.7 • C ^0.2 • V ^0.8 , of the second and subsequent layers - h ₂ = A ₁ • W ^-3.7 • C ^0.2 • V ^0.8 , where W is the initial moisture content of the grain,%; C is the concentration of ozone in the mixture, mg / m ³ ; V is the speed of the ozone-air mixture in the layer, m / s; A and A ₁ are the coefficients accepted for wheat grain A = 23.3 • 10 ⁴ and A ₁ = 21.3 • 10 ⁴ ; for barley grain A = 26.8 • 10 ⁴ and A ₁ = 24.3 • 10 ⁴ , for oat grain A = 28.5 • 10 ⁴ and A ₁ = 26.9 • 10 ⁴ .

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