RU2519809C1 - Method of drying seeds and grains and device for its implementation - Google Patents

Abstract

FIELD: agriculture.

SUBSTANCE: method of drying seeds or grains is that the material is loaded, circulated, periodically monitored, exposed with heated and unheated drying agent, cooled and discharged. The ratio of exposure duration to the material with the heated and unheated drying agent and the number of cycles of oscillation while the material rotation between the binning is determined. The duration of the intermediate binning is less than 0.5 hours. The device for drying seeds and grains comprises over-the-drier hopper, the drying chamber, the outer and inner perforated cylinders, the vertical auger, the heater, the system of loading and unloading means, the wheeled mover, as well as the discharge pipe of selection of grains from the boundary layer.

EFFECT: improving efficiency of drying while drying small batches of seeds and grains.

2 cl, 2 ex, 1 dwg

Description

The invention relates to the drying of seeds and grain and can be used in agriculture, in the procurement system, food and chemical industries.

A known method of drying grain in batch plants: a portion of the grain is loaded into the drying chamber, exposed to a drying agent for a certain time, cooled and unloaded.

A device for implementing this method is known, containing a drying chamber, a heat source and a fan (V.I. Aniskin, G.S. Okun. Technological basis for evaluating the operation of grain drying plants, M .: GNU VIM, 2003, pp. 140-143).

These plants, as a rule, are simple in design, easy to maintain and widely distributed in agriculture of the Russian Federation, especially in farmers and small farms (less than 500 tons of grain per season). However, they are inefficient and energy-consuming.

There is an oscillating method of drying grain, according to which it is circulated with exposure to it with a heated and unheated drying agent and intermediate bedding. Heating is carried out in a suspended layer with a period of 5-6 s, and cooling in a descending gravitational layer with a period of 5-6 minutes, and the material’s turnover cycle; (from draining to draining) coincides with the oscillation cycle. (I.L. Lyuboshits, L.S. Slobodkin, I.F.Pikus Drying of dispersed heat-sensitive materials: “Science and Technology”, Minsk, 1969, p. 122-124).

This drying method is closest to the claimed and adopted as a prototype.

The disadvantage of this method is that despite the energy efficiency and high quality of the obtained seeds and grains, the technological scheme and constructive implementation are quite complex, and the method itself has reserves of intensification. In agriculture, the method and device have no prospects, in particular in farmers and small farms.

A mobile device for circulating drying of seeds and grain is known, including a drying chamber with a drying hopper, external and internal perforated cylinders, a vertical screw that continuously moves grain in the chamber, an air heater, a fan, a system of loading and unloading means and a wheel drive (MESMAR SSI25 mobile grain dryers / 21OT2 Electronic resource http: / www / baitekrnach: nery.ru/

This device is the closest to the claimed one and is taken as a prototype, but it works with a constant supply of a drying agent and has reserves of intensification when switching to an oscillating mode.

An object of the invention is to increase the efficiency of mobile grain dryers, which can be widely used in agriculture of the Russian Federation when drying small batches of seeds and grain.

, где n для материала с гигроскопической влажностью и выше равно ~ 1,25, для материала с меньшей влажностью n~1,15, а количество циклов осциллирования при обороте материала между отлежками составляетThe problem is achieved in that in the method of drying seeds and grain, which consists in loading the material, circulating, periodically tracking and exposing it with a heated and unheated drying agent, drying, cooling and unloading, according to the invention, the ratio of the duration of exposure of the material to the heated τ _p and the unheated τ _n drying agent is $$\frac{{\tau }_n}{{\tau }_n}\le n$$

, where n for a material with hygroscopic humidity and higher is ~ 1.25, for a material with lower humidity n ~ 1.15, and the number of oscillation cycles during a material revolution between drains is

, $$K=\frac{G_{\mathrm{to}}}{P_w{\tau }_n\left(n+\mathrm{one}\right)}$$

,

where G _to , P _W - respectively, the capacity of the drying chamber (t) and the productivity of the means circulating the material, t / h, in addition, the duration of the intermediate overburden is not less than 0.5 hours

,The task is also achieved by the fact that the device containing a drying hopper, a drying chamber, an external and internal perforated cylinders, a vertical screw, a heater, a fan, a system of loading and unloading means, a wheel drive, according to the invention is equipped with an outlet pipe for grain selection from the boundary layer, and height H of the drying hopper - not less than $$H=\frac{P_w{\tau }_{\mathrm{about}\tau }}{\mathrm{<figure-callout\; id="2"\; label="\pi \; D\; n"\; filenames="00000015.png"\; state="\{\{state\}\}">\pi \; </figure-callout>}{D}_n^{}{}_2^{}\gamma }$$

,

where τ _from - the duration of the tracking, h; D _m - diameter of the drying hopper (external perforated cylinder), m; γ is the bulk mass of grain, kg / m ³ .

The invention is illustrated in the drawing, which shows a diagram of the device.

The device includes a visor 1, a drying hopper 2, an internal perforated cylinder 3, an external perforated cylinder 4, a drying chamber 5, an air duct 6, an air heater 7, a fan 8, an internal air cavity 9, an outlet pipe for sampling grain boundary layer 10, a valve 11, a drying hopper 12, racks 13, loading valve 14, wheel 15, frame 16, loading means 17, vertical screw 18, level sensors 19, discharge pipe 20, unloading valve 21, control panel 22.

In addition, the diagram shows wet grain 23, dried grain 24, circulating grain 25.

The operation of the device is as follows.

Wet pre-cleaned grain 23 with the loading means 17 and the vertical screw 18 is fed into the drying hopper 2, the valve 21 is turned on for circulation, the drying hopper 12 is filled, the drying chamber 5 and the drying hopper 2, when the upper level sensor 19 is activated, the loading stops. When the device is full, the fan 8 is turned on, the drying agent (outside air) is heated in the air heater 7 and pumped into the internal air cavity 9 through the air duct 6, and then the drying agent is filtered through a layer of material in the drying chamber 5.

Upon reaching the grain conditional moisture shut off the heater 7 and cool the grain. Upon completion of cooling, the fan 8 is turned off, the valve 21 is switched to unload and the device is unloaded.

Using the remote control 22 perform the following operations: turn on and off the means of loading, moving material in the device, fan 8, air heater 7. Valves 14 and 21 are put into operation by levers. The control panel 22 displays the temperature indicators of the drying agent and grain, and the temperature of the drying agent is maintained automatically, and upon reaching the set temperature for heating the grain, the air heater 7 is turned off. The control of the drying process (temperature and humidity conditions) is also carried out using the outlet pipe 10, through which grain samples of the boundary layer are taken from the surface of the inner perforated cylinder 3 having a maximum temperature.

The method is as follows.

The grain is loaded, tracked in a drying hopper, gravitationally moved in a drying chamber, subsequently exposed to it with an unheated, preheated and reheated drying agent, moved vertically, again traced, and so on for several cycles when the grain reaches a conditioned humidity, then it is cooled and unloaded.

The ratio of the periods of heating and cooling of the material during oscillations (heating - cooling) under the same state of the layer - dense or fluidized, as a rule, is taken equal to unity so that, on the one hand, the material does not overheat, and on the other, to avoid unreasonable heat losses . However, with a sufficiently long caking time, moisture from the kernel of the kernels moves into the shells and easily evaporates in the drying chamber when the grain is exposed to a heated drying agent. The temperature of the grain (isothermal drying) not only does not increase, but can even be slightly reduced (V.A. Sharshunov, L.V. Rukshan. Drying and storage of grain, Minsk, Misanta, 2010, p.236).

Tracking helps to increase the diffusion coefficient and the rate of contact heat and moisture exchange and ultimately increase the ratio of τ _p / τ _n , i.e. quantities n.

The value of n can be approximately estimated as follows: it is known that ~ 15% of the heat is the difference between the heat of vaporization of the grain water and evaporation from the free surface, i.e. by these ~ 15% it is possible to increase τ _n (V.I. Aniskin, G.S. Okun Technological basis for drying the operation of grain drying plants, GNU VIM, M., 2003, 38-39) and ~ 10% for contact moisture transfer between the dried and wet grain during bedding, which does not have time to penetrate into the core during bedding and evaporates from the shell as free without increasing grain temperature (S.D. Ptitsyn Zernosushilki, Mashgiz, M., 1962).

Thus, for grain with humidity equal to or more hygroscopic (W≥21%) n≈1.15 + 0.1 = 1.25, and for W <21%, when contact transfer can be neglected n≈1.15.

The duration of the passage of the material of the drying chamber will be

$${\tau }_{\mathrm{to}}=\frac{G_{\mathrm{to}}}{P_w},(\mathrm{one})$$

where G _to , P _W - respectively, the capacity of the drying chamber (t) and the productivity of the means of circulating the material, t / h The duration of a separate oscillation cycle τ _i

$${\tau }_i={\tau }_n\left(n+\mathrm{one}\right)(2)$$

The number of cycles per material revolution

$$K=\frac{G_{\mathrm{to}}}{P_w{\tau }_n\left(n+\mathrm{one}\right)}(3)$$

The larger the K value, the lower τ _n and, accordingly, the higher the temperature of the heated drying agent and the higher the efficiency of the process.

The value of τ _{n is} usually taken in the range of 3-6 minutes or calculated on the basis of the heat balance of the boundary layer of the material, which is most exposed to temperature.

From the heat balance follows (B.S. Sazhin Fundamentals of drying technology, M., Chemistry, 1984, p. 30)

where C is the heat capacity of the material; K ₁ is the transition coefficient from the elementary layer to the boundary; η is the fraction of heat that went into the evaporation of moisture; α is the heat transfer coefficient, W / m ² · C; f is the specific surface of the material; t ₁ , θ _nq , θ _ox - respectively, the average temperature of the heated drying agent, the permissible temperature of heating and cooling grain.

By taking grain samples from the outlet pipe 10 and measuring its temperature, it is possible to adjust both the drying temperature and τ _n

The duration of curing, in which most of the moisture from the kernel is transferred to the surface of the grain at a temperature of ~ 5 ° C, is at least 15 minutes (V.M. Lurie, Investigation of the process of cooling seed grain, author. Thesis for a sausage. Scientific step. Candidate of Technical Sciences M. VIM-VIESH, 1970, p. 20). The average temperature of the grain during drying at the initial at 20 ° C and final 45 ° C is θ ~ 32.5 ° C. Taking as a first approximation a quadratic dependence of the duration of tracking on the grain temperature, we obtain the minimum necessary duration at τ θ≈32.5 ° С

τ _from - the minimum duration of tracking, h

Drying bin capacity can be recorded

$$G=\frac{\pi D_{\mathrm{<figure-callout\; id="2"\; label="m"\; filenames="00000015.png"\; state="\{\{state\}\}">m</figure-callout>}}^2}{\mathrm{four}}\gamma H,(6)$$

where D _m is the diameter of the outer cylinder, m; H - height of the drying hopper, m; γ is the bulk mass of the grain, t / m ³ .

Its capacity can also be written as

$$G=P_w\cdot {\tau }_{\mathrm{about}t},(7)$$

From (6) and (7) it follows that the height of the drying hopper should be at least

$$H=\frac{\mathrm{four}{P}_w{\tau }_{om}}{\pi {\mathrm{<figure-callout\; id="2"\; label="D\; m"\; filenames="00000015.png"\; state="\{\{state\}\}">D\; </figure-callout>}}_m^{}\gamma },m$$

Example 1. At LLC Agrofirm Korshik in the Orichevsky district of the Kirov region, mobile SSI / 21OT2 dryers were tested, which switched to an oscillating drying mode.

The grain mixture (wheat + oats + barley) was dried with a moisture content of 24.05% to 12% per feed. 17.4 tons were loaded, the dried mixture was unloaded in an amount of 14.3 tons, ~ 3.1 tons of moisture was evaporated, the drying time was 4, 9 hours. The maximum temperature of the drying agent was 130 ° C, the outdoor temperature was 11 ° C.

The productivity of the dryer was 5.35 plt / h, compared with the control experiment carried out under the same conditions, but with a constant temperature of the drying agent equal to 110 ° C, it decreased by ~ 14%, but the specific fuel consumption (natural gas) ) amounted to 4.10 nm ^{3 /} pl.t, versus 4.85 nm ^{3 /} pl.t in the control experiment, i.e. decreased by ~ 15%. The temperature of the dried material in both cases was ~ 48 ° C.

Example 2. We determine the parameters N, K. The SSI / 21OT2 dryer has the following characteristics

D _n = 3.15 m; the diameter of the inner chamber D _ext ≈2.0 m; height of the drying bin H _over = 1.8 m; the height of the drying chamber N _to = 2.5 m; P _W ≈20 t / h When τ _from = 0.5CH; γ = 0.75 t / m ³ ; P _W = 20 t / h, H≈1.7 m.

At the indicated temperature of the drying agent on the forage, it is advisable to take τ _n = 6 min and in this case the value of K will be

$$K=\frac{\pi \left(D_n^2-D_{\mathrm{at}l}^2\right)\cdot \gamma H_{\mathrm{to}}}{\mathrm{four}{P}_w\cdot 2.25{\tau }_n}=\frac{\left({3.15}^2-2\right)0.75\cdot 2.5}{\mathrm{0,07}\cdot \mathrm{four}\cdot 2.25\cdot \mathrm{twenty}}\approx 2$$

With a slight decrease in productivity, a significant reduction in fuel costs was achieved.

The efficiency of the oscillating drying is achieved through the use of curing and increased temperature of the drying agent.

Claims (2)

1. The method of drying seeds and grain, which consists in the fact that the material is loaded, circulated, periodically traced and exposed to a heated and unheated drying agent, dried, cooled and unloaded, characterized in that the ratio of the durations of exposure to the material with heated τ _n and unheated τ _n drying agent is

, where n for a material with hygroscopic humidity and above ~ 1.25, for a material with lower humidity ~ 1.15, and the number of oscillation cycles during a material revolution between stays is

,
where G _to - the capacity of the drying chamber, t; P _W - productivity means circulating the material, t / h;
in addition, the duration of the intermediate bedtime is less than 0.5 hours. 2. A device for drying seeds and grain, containing a drying hopper, a drying chamber, an external and internal perforated cylinders, a vertical screw, a heater, a system of loading and unloading means, a wheel drive, characterized in that it is equipped with an outlet pipe for grain selection from the boundary layer, and the height of the drying hopper is not less

,
where P _W - the productivity of the vertical screw, t / h;
τ

- the duration of the bedding, h; D _n - diameter of the drying hopper (outer perforated cylinder), m; γ is the bulk mass of grain, kg / m ³ .

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