RU2395047C1 - Method and device for drying of seeds and grain - Google Patents

Abstract

FIELD: agriculture.

SUBSTANCE: grain is charged into airslide conveyor, ventilated with external and heated air and unloaded. The novelty of the method is the fact that discharge losses in ventilated layer ΔP_c shall comply with the condition ΔP_c<KP, and heating extent shall be limited with relative moisture of air coming out of the layer φ≤85…90%, where K=P/P₁, P - full discharge of fan, P₁ - discharge of fan at maximum delivery. Device for drying of seeds and grain comprises charging and discharging facilities, grid, fan and heater. The novelty of device is the fact that it is equipped with at least four sensors with relative air moisture φ, arranged over a layer of material along its length as pairwise in peripheral zone of chamber, and integrator connected to heater with the possibility to change temperature of heated air.

EFFECT: improved efficiency of seeds and grain drying.

2 cl, 4 dwg

Description

The invention relates to the drying of seeds and grains, mainly of high humidity, and can be used in agriculture.

A known method of drying seeds and grain, in which the wet material is loaded onto the grate surface of the chamber, ventilated with external and heated air, dried to a conditioned humidity and unloaded.

A device for its implementation, containing means of loading, unloading, a camera, a grill, a fan and a heater [1].

These method and device are widely used in agriculture, they allow to dry or dry seeds and grain of any initial moisture content, including elite seeds. However, the method is inefficient and energy-consuming, and manual labor is required to service the device.

There is a known method of drying seeds and grains, in which they are loaded into an aeration channel, ventilated with external and heated air, and unloaded. The air is heated to 27 ° C, and the material is dried with a drying agent in a drying chamber. The drying quality is ensured by oriented feeds of material and air along the length of the aeroflot. This method has found application in regions of high humidity (W≥21%).

However, the moisture removal in the aeroshaft during ventilation with outside air is insignificant, and the use of heated air is limited by the condensation in the upper layers of the embankment with the formation of a crust that prevents ventilation [2].

A device containing loading and unloading means, a grill, a fan and an air heater is known. The device provides an oriented flow of material and air [3]. A disadvantage of the known device is the difficulty of controlling the degree of heating of the air.

These method and device are closest to the essence of the claimed and selected for the prototype.

The technical task of the invention is to increase the efficiency of ventilation of seeds and grain, including heated air.

The stated technical problem is achieved by the fact that in the method of drying seeds and grains, in which they are loaded into an aeration channel, ventilated with external and heated air and unloaded, according to the invention, the pressure loss in the ventilated layer ΔР _c must meet the condition ΔР _c ≤КР, and the degree of heating is limited the relative humidity of the exhaust air from the layer φ≤85 ... 90%, where K = P / P ₁ , P is the total pressure of the fan, and P ₁ is the pressure of the fan at maximum flow.

The technical task is also achieved by the fact that in the device for drying seeds and grain containing means of loading and unloading, a grill, fan and air heater, according to the invention, the device is equipped with at least four sensors relative humidity φ located above the layer along its length in the peripheral part camera, and an integrator connected to the installation air heater with the ability to change the temperature of the heated air.

Comparison of the claimed method with the prototype shows that the new method is that the pressure loss in the ventilated layer ΔР _c must meet the condition ΔР _c ≤КР, and the degree of heating is limited by the relative humidity of the air leaving the layer φ≤85 ... 90%.

Comparison of the claimed device with the prototype shows that the new device is that the device is equipped with at least four relative humidity sensors φ, placed above the layer along its length, in pairs in the peripheral part of the chamber, and an integrator connected to the heater with the possibility of changing the temperature of the heated air.

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

The claimed method can only be implemented in the proposed device, which indicates compliance with the principle of "unity of invention".

The invention meets the criterion of "inventive step", as a result can be achieved that satisfies the existing need, namely: improving the efficiency of ventilation of seeds and grain.

The invention is also “industrially applicable”, as it can be used in agriculture.

The invention is illustrated by drawings: in figure 1 shows a General view of the device, figure 2 and 3 graphs obtained by substantiating the method.

The device contains a heater 1, fan 2, loading means 3, flooring 4, grating 5, a mound of material 6, a chamber 7, a shutter 8, a means of unloading 9, relative humidity sensors 10, an integrator 11 are located on the grating.

The method is as follows: with a mobile loading device 3 fill the chamber of the air duct 7, turn on the fan 2, and, if necessary, the air heater 1 and ventilate the bulk of the material 6. After drying, open the shutter 8 at the outlet of the chamber 7 and, when a fluidized bed is formed at the outlet of the grate, unload the material into the means unloading 9 (e.g. scraper conveyor). With increased relative humidity of the outside air (φ≥75 ... 80%,), the drying process is rather slow, and drying to standard humidity (14%) is impossible, therefore, the outside air is heated at 2 ... 8 ° С. Ventilation with heated air is characterized by its intense saturation with moisture vapor and the formation of a drying front in the embankment: at the inlet of the air flow into the layer, the material is dried out, and at the outlet its humidity increases due to condensation of moisture vapor at φ≥95%. In this case, a crust may form, material deterioration occurs, and pressure losses also increase. In order to prevent crusting, it is necessary to reduce the value of φ, i.e. the temperature of the heated air, which is achieved by triggering the sensors φ, since the intensity of ventilation of the embankment along the length of the air duct changes, then the sensors should be placed along its length. In addition, when loading material, light and small impurities roll down from the surface of the embankment to its peripheral zone, where intergranular channels are partially covered. Due to this, the air velocity decreases in the peripheral zone of the embankment and the degree of saturation increases and the likelihood of crust formation; therefore, the φ sensors should be placed in pairs on both sides of the embankment in these zones, and the integrator averages the values of the φ sensors.

On the control panel of the air heater there is a hygrometer with a dedicated scale in the range of 85 ... 90% relative humidity of the exhaust air. Within the limits of this interval, a relay is triggered with one or several additional sections of the heater turning off or off, depending on the actual value of φ.

Depending on the type of fan, the value K = P / P ₁ can vary within wide limits: for example, for high pressure fans of the type VVD or Ts 10-28, the value K≈1, i.e. pressure losses are weakly dependent on flow. However, these fans in comparison with medium pressure fans are inefficient and are not used on aerial chutes.

Medium-pressure fans C 4-70, C 4-76 have a gentle characteristic - the value of K varies for most of these types of numbers from 0.18 to 0.22 [3]. Therefore, the smaller the value of K, the greater the value of P _c and the height of the layer in the air duct.

In aerial chutes, it is advisable to dry the seeds and grain of high humidity (W≥20%). This is because with high humidity, the air leaving the embankment is saturated with moisture as much as possible and each kg of air carries out from 1.0 to 1.5 g of moisture. At humidity W <20%, the degree of saturation of air with moisture and moisture removal are reduced, and the aeration channel, as a rule, is used not for drying, but for temporary storage of seeds and grain.

Example. At Voronezhsky LLC, Vladimirovsk Region, wheat grain with a moisture content of 22% was loaded into an aerial trench ~ 12 m long and 25 t capacity at a maximum embankment height of 2.5 m, the embankment was purged with a fan of type C 4-76 No. 8-3. The maximum pressure of the fan at a flow of 16 thousand m ³ / h is P = 2.2 kPa, and the maximum flow of 30 thousand m ³ at P = 1.6 kPa [3]. The grain was ventilated for 4 hours, then the aerial trench was unloaded, the grain was preliminarily cleaned and loaded into the SZK-8 dryer and dried.

An experiment was carried out to ventilate grain in an aerial chute with various heights of embankment 0.5; 1.2 and 2.2 m both outside and heated at 5 ° C air.

We measured the pressure loss in the installation and embankment, air flow, moisture removal for 4 hours and the relative humidity of the outdoor and exhaust air.

It was found that with increasing layer height H, the pressure loss in the embankment ΔР _c (1, Fig. 2) increases, the air flow Q (2) does not change practically to ~ 1.6 kPa (K = 0.18). Also, the pressure loss in installation (3) does not change, with a further increase in the height of the embankment and ΔР _{c, the} Q value decreases rapidly.

Similarly, Q is changed by moisture removal ΔW both during ventilation with external (4) and with air heated at 5 ° С (5).

When ventilating the embankment with outside air, seeds and grains of high humidity (W> 20%), regardless of the relative humidity, do not form condensate in the layer and there is no need to control φ.

However, at φ ₀ ≥75%, the moisture loss of the material does not exceed d = 0.9 g of water / kg of air and drying continues for a long time. When air is heated by 1 ° С, its relative humidity decreases by ~ 5%, thus, by heating air by ~ 5 ° С with a relative humidity of φ _о = 75%, it is possible to reduce φ to 50% and provide satisfactory drying at a heat consumption of 2 ... 2.5 times lower than in grain dryers. It was found that when ventilating with outside air with φ ₀ ≈70%, the relative humidity φ (Fig. 3, Item 1) at the outlet of the embankment does not exceed 90 ... 95% and condensation does not occur. When ventilating with heated air (Fig. 3, item 2), the formation of condensate and a more significant decrease in the flow rate Q were established.

When implementing the method, it is necessary to determine the total head P and head P ₁ at the maximum flow θ from the characteristics of the selected fan. The difference of these heads РР Р ₁ is the admissible pressure loss in the embankment ΔР _c . In accordance with the found value ΔР _c , the height of the embankment H is determined with the known value of Q and the characteristics of the material. The pressure loss in the layer ΔР _{c of the} air duct can be determined from the expression for calculating the pressure loss during radial filtration [4]:

;Where

;

K is the Cozeny-Karman constant; ή - coefficient of dynamic viscosity of air, kg / s · m; S _V is the specific surface area of the grain in the layer, m ² / m ³ ; ε is the porosity of the layer; β is a constant; γ _in - air density, kg / m ³ ; V ₀ - air velocity at the entrance to the grain layer, m / s; r ₀ is the radius of the central cylinder (in our case, r ₀ ≈B / 2, B is the width of the air duct), m.

It is also proposed that the resistance of the grain layer ΔР _s when ventilating the embankment with a radial air flow is determined by the equation [4].

where A, B are the coefficients characterizing the properties of the grain material; Q - air flow, m ³ / s; L is the thickness of the grain layer, m; α is the central angle of the aerial groove, deg; R is the outer radius of the contour of the embankment, m; r is the radius of the air distribution pipe, m (in our case, r≈B / 2; where B is the width of the air duct).

The calculation of ΔР _c using these formulas is complicated by the lack of information on the values of K, β (1) and a, in (2), therefore, a more reliable determination is the experiment (Fig. 2).

Sources of literature

1. M.A. Telengator, V.S. Ukolov, V.M. Tsetsinovsky Seed processing of grain crops, Kolos M., 1972, p.31 ... 33.

2. GS Berezovsky Justification of the method and means of preliminary drying of seeds of high humidity // Author for a competition. training senior candidate of technical science, Kostroma 2000, p.5-6, 18.

3. Guidelines for drying and cooling grain by active ventilation, VIM, M. 1974, S. 42-44.

4. V.I. Aniskin, V.A. Rybachuk. Theory and technology of drying and temporary preservation of grain by active ventilation, VIM, M. 1972, S. 57-61.

Claims (2)

1. The method of drying seeds and grain, in which they are loaded into an aeroshaft, ventilated with external and heated air and unloaded, characterized in that the pressure loss in the ventilated layer ΔP _c must meet the condition ΔP _c ≤KP, and the degree of heating is limited by the relative humidity of the outgoing air layer φ <85 ... 90%, where K = P / P ₁ ; P - full head of the fan, P ₁ - head at maximum flow. 2. A device for drying seeds and grains containing loading and unloading means, a grate, a fan and a heater, characterized in that the device is equipped with at least four sensors of relative humidity located above the layer of material along its length in pairs in the peripheral part of the chamber, and an integrator connected to the air heater of the unit with the ability to change the temperature of the heated air.

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