Parameters of the seed output device of the ergot isolation machine

. Grains of rye, wheat, barley and oats are often infected with poisonous ergot fungi. Therefore, it is necessary to clean the grain from harmful impurities. Modern machines do not provide the isolation of ergot sclerotia from grain due to the closeness of their properties in terms of air flow rate and linear dimensions. Cleaning seeds from ergot sclerotia, which have a density lower than the density of the grain, is possible in an aqueous solution of salt. When developing such a machine, research is required to study the residence time of grain in an aqueous salt solution. Grains are considered in the form of a transverse cylinder and an elongated ellipsoid of rotation with numerical values of the parameters: density ρz = 1.2...1.5∙103 kg/m3, length lz = 5.0...10.0∙10-3 m, width b = 1.4...3.6∙10-3 m and thickness δ = 1.2...3.5∙10-3 m. Theoretical studies were carried out on the basis of methods of mathematical modeling, classical mechanics using the laws of hydrodynamics. It was found that when using in the machine for the isolation of toxic ergot sclerotia from the grain of an aqueous solution of salt with a density ρzh = 1000...1150 kg/m3 and a height h1 = 0.35...0.60 m in a bath, the total time ttotal of seeds residence varies within 7.6...18.8 s. During this time, the seeds are moistened superficially, to eliminate which it is enough to blow them under the pressure of atmospheric air.


Introduction
The grain of the main grain crops (rye, wheat, barley and oats) is the oldest human food and feed for farm animals. However, cereals such as winter rye, wheat, barley and oats are often infected with poisonous ergot fungi [1,2].
Currently, grain production is mechanized. Harvesting is carried out by combine harvesters [3,4,5]. After threshing the grain mass with these combines, due to the imperfection of their cleaning mechanism, the grain heap contains grain, organic and mineral impurities, as well as harmful impurities, which include poisonous ergot sclerotia [6,7,8].
Therefore, to obtain grain suitable for food, technical and seed purposes, the separation of various impurities from the grain heap is carried out by machines of preliminary, primary and secondary cleaning [9][10][11][12].
These machines are complex and therefore costly. These machines do not provide the release of poisonous ergot sclerotia in one technological process due to the closeness of their physical and mechanical properties in terms of air flow velocity and linear dimensions (width, thickness and length) [13][14][15][16][17][18][19][20][21][22][23].
Research on improving the design and technological process of these machines does not solve the problem noted [24,25].
This circumstance requires the creation of a less energy-intensive and more efficient machine for the isolation of toxic ergot sclerotia from seed material. This machine should have simple, easy-to-adjust and maintain main working parts [27].
One of the ways to solve this issue is to create a machine for the isolation of toxic ergot from grain, consisting of a bath with an aqueous solution of salt, conveyors of seeds and waste, a hopper with a feeder and a tank with an aqueous solution of salt [28].
When developing such a machine, research is required to study the residence time of grain in an aqueous salt solution. If the grain is aqueous salt solution for a long time, it is possible for liquid to penetrate through their shell. This circumstance causes an increase in grain moisture. Increasing grain moisture requires additional drying costs for long-term storage of seeds. This circumstance also worsens the flowability of seeds when sowing with seeders. In addition, the penetration into the seed of an aqueous solution of chlorinecontaining salt can have a negative effect on its germination. Therefore, it becomes necessary to consider the process of withdrawing seeds from a bath with an aqueous solution of salt of the machine for the isolation of toxic ergot sclerotia.

Materials and methods
Theoretically, the residence time of grains in an aqueous solution of salt of a machine for the isolation of toxic ergot sclerotia from grain is considered. Grains are considered as a model of a transverse cylinder and an elongated ellipsoid of revolution. In accordance with this, the scientific concept of a cylindrical grain was introduced for the model of a transverse cylinder, and a spheroidal grain for the model of an ellipsoid of revolution.
For theoretical calculations, the following numerical values of the grain parameters were taken: density ρz = 1.  [26].
Theoretical studies on the immersion of grains in a liquid of various density ρzh and their removal from a bath with an aqueous salt solution were carried out on the basis of mathematical modeling methods and classical mechanics.
The experimental data were processed on a SAMSUNG NP-R540H personal computer using the Excel 2013 statistical data processing application from the Microsoft Office 2013 office software package, as well as using the SigmaPlot 11.0 special statistical data processing software. The resulting graphic dependencies were created in the vector graphics editor CorelDRAW 12.

Results and discussion
When a grain, considered in the form of models of a transverse cylinder (cylindrical grain) and an elongated ellipsoid of revolution (spheroidal grain) [29], falls from a minimum height h onto the surface of the liquid to overcome surface tension forces, it moves in it at a speed ʋz to the bottom of the tank 1 of the machines for the isolation of toxic ergot sclerotia. Further, the grains move at a speed ʋup along the bottom of the bath by scrapers 5 of the lower branch of the conveyor 2 and are taken out through the sloping board 3. When the conveyor 2 moves rye seeds in the unloading direction, the aqueous salt solution from them flows down the sloped bottom back into the bath 1 through the gap Δ between the working the edge of the scrapers 5 and the bottom.
The general scheme of immersing and removing of rye seeds from the bath of the machine for the isolation of toxic ergot sclerotia with an aqueous solution of salt is shown in Figure 1.
-direction of withdrawal of winter rye seeds where h1 -the height of the aqueous solution of salt in the bath of the machine for the isolation of toxic ergot sclerotia, m.
The time tup of the lifting of grains from an aqueous solution of salt by the conveyor scrapers of the machine for the isolation of toxic ergot sclerotia is , where L -the length of the bottom of the bath with an aqueous solution of salt of the machine for the isolation of toxic ergot sclerotia under the conveyor for removing rye seeds, m; ʋup -linear speed of rye seeds lifting along the bottom of the bath by the conveyor of the machine for the isolation of toxic ergot sclerotia, m/s. The length of the bottom of the bath with an aqueous solution of salt under the conveyor for removing rye seeds is determined by the formula: , where α -the angle of inclination of the bottom of the bath of the machine for the isolation of toxic ergot sclerotia to the horizontal, deg.
Taking into account the need to maintain the continuity of the technological process for removing rye seeds from the bath of the machine for the isolation of toxic sclerotia and excluding their accumulation in it, the time tп of immersing the seeds to the bottom of the bath should be no less than the time tup of lifting them from an aqueous solution of salt with the conveyor scrapers of the machine for the isolation of ergot sclerotia. It is also necessary that the geometric dimensions of the scrapers (width and height), their number and distance between them correspond to the requirement: the flow of grains falling in the solution was not more than the flow of grains taken out by the conveyor.
For the case when tп = tup the following relation is fulfilled: Then the total residence time of rye seeds in the bath of the machine for the isolation of toxic ergot sclerotia with an aqueous solution of salt, taking into account expressions (1) and (2), will be .
The accumulation of grains when removing grain depends on the gap Δ between the bottom edge of the scrapers and the bottom of the bath.
The surface of the dependence of the total residence time ttotal of rye seeds in an aqueous solution of salt of the machine for the isolation of toxic ergot sclerotia on the density ρzh of the solution and its height h1 is shown in Figure 2, taking into account the expressions for the velocity ʋz of movement of a weevil in a liquid, considered in the form of models of a transverse cylinder (cylindrical grain) and an elongated ellipsoid of revolution (spheroidal grain) and presented in work [30].
The surface of the dependence ttotal = f(ρzh, h1) is constructed for the calculated average velocities υz mean of grain movement in a liquid with a density of ρzh =  From the analysis of the surface it can be seen that with an increase in the density ρzh of the aqueous salt solution and its height h1 in the bath, the time ttotal of the grain in it increases. With the density of the liquid ρzh = 1000 kg/m3 (water) and its height h1 = 0.35 m, the total time ttotal of the stay of rye seeds in it is 7.6 s, and at a height of h1 = 0.60 m this time is ttotal = 13.0 s. At a density of an aqueous solution of salt ρzh = 1150 kg/m3, corresponding to the upper limit of the density ρс of ergot sclerotia, and its height h1 = 0.35 m, the time ttotal = 10.9 s, and in the case of a maximum height h1 = 0.60 m of an aqueous solution salt in the bath of the machine for the isolation of ergot sclerotia, the time ttotal, the residence time of the grain in it increases to 18.8 s.
Consequently, the total time ttotal the stay of rye seeds in an aqueous solution of salt of the machine for the isolation of toxic ergot sclerotia is completely insignificant. In such a short time, an aqueous salt solution is not able to pass through the grains shell inside. This excludes an excessive increase in grain moisture. To eliminate surface moisture of the grain, it is enough to blow it under the pressure of external or heated atmospheric air.
The linear speed ʋup of rye seed lifting along the bottom of the bath by the conveyor of the machine for the isolation of toxic ergot sclerotia is determined by the formula [31]: , where ω1 -angular speed of rotation of the drive shaft of the conveyor of rye seeds of the machine for the isolation of toxic ergot sclerotia, rad./s; Rе -the outer radius of the circle of the leading sprocket on the drive shaft of the rye seed conveyor of the machine for the isolation of toxic ergot sclerotia, m; п1 -frequency of rotation of the drive shaft of the rye seed conveyor of the machine for the isolation of toxic ergot sclerotia, min-1.
Then from expression (7), taking into account formula (5), the frequency n1 of rotation of the drive shaft of the rye seed conveyor of the machine for the isolation of toxic ergot sclerotia is determined The diameter of the outer circumference of the leading sprocket on the drive shaft of the rye seed conveyor machine for the isolation of toxic ergot sclerotia is expressed [32] , where t1 -leading sprocket pitch on the drive shaft of the rye seed conveyor, mm; z -number of the leading sprocket teeth on the drive shaft of the rye seed conveyor, pc. Then, taking into account expression (9), introducing a coefficient of 2.0 due to the volumetric intake of grain by scrapers from the bottom of the bath, the rotational speed of the drive shaft of the rye seed conveyor, represented by formula (8), is determined as follows (min-1): .
The obtained expression (10) makes it possible to determine the frequency п1 of rotation of the drive shaft of the rye seed conveyor of the machine for the isolation of poisonous ergot sclerotia, depending on the pitch t1 of the leading sprocket and the number z of its teeth, as is customary in technical calculations.
The surface of the dependence of the frequency п1 of rotation of the drive shaft of the conveyor for removing rye seeds from an aqueous solution of salt on its density ρzh and the number z of the teeth of the leading sprocket is shown in Figure 3, taking into account the expressions for the velocity ʋz of grain movement in a liquid, considered in the form of models of a transverse cylinder (cylindrical grain) and an elongated ellipsoid of revolution (spheroidal grain) and presented in work [30].
To determine the frequency n1 of rotation of the drive shaft of the conveyor for removing rye seeds from the bath, the step of the leading sprocket t1 = 12.7 mm and the angle of inclination of the bath bottom α = 40° were adopted as the most rational parameters for this design of the machine for the isolation of toxic ergot sclerotia from rye grain.
From the obtained graph it follows that with an increase in the density ρzh of an aqueous solution of salt and an increase in the number z of the teeth of the leading sprocket on the drive shaft of the conveyor, the frequency п1 of its rotation decreases. When varying the number z of the teeth of the leading sprocket on the drive shaft of the conveyor within 24...34 pc. the maximum values of its rotation frequency п1 are observed at a liquid density ρzh = 1000 kg/m3. This is due to the faster immersion of the grain in water than in a salt solution, and, accordingly, the need to remove the grain from the bath with a conveyor with a high frequency п1 of its rotation. So, in the case of using a leading sprocket with an increasing number of teeth z = 24, 26, 28, 30, 32 or 34 рс., the frequency п1 of rotation of the conveyor shaft decreases and, accordingly, is 14.2; 13.1; 12.1; 11.3; 10.6 or 10.0 min-1. The minimum values of the frequency п1 of rotation of the conveyor are fixed at the density of an aqueous solution of salt ρzh = 1150 kg/m3, corresponding to the upper limit of the density ρс of ergot sclerotia. In the case of using a leading sprocket with a number of teeth z = 24 pc. the frequency п1 of rotation of the conveyor is 9.9 min-1, and with an increase in the parameters z of the leading sprocket, the values of п1 decrease and at z = 34 pc. are already make up 6.9 min-1.
Thus, in order to carry out the technological process with proper efficiency by a machine for the isolation of toxic ergot sclerotia, the frequency п1 of rotation of the conveyor for removing rye seeds from an aqueous salt solution depends on its density ρzh and the number z of the teeth of the leading sprocket.

Conclusion
When using an aqueous solution of salt with a density ρzh = 1000...1150 kg/m3 and a height h1 = 0.35...0.60 m in the bath in the machine for the extraction of ergot sclerotia from rye grain, the total residence time ttotal of rye seeds varies within 7.6...18.8 s. In such a short time, rye seeds are moistened only superficially, to eliminate which it is enough to blow them under the pressure of outside or heated atmospheric air.
In this case, the frequency п1 of rotation of the rye seed conveyor is 6.9...14.2 min-1 using of the leading sprocket with the number of teeth z = 34, 32, 30, 28, 26 and 24 pc. respectively. Due to the possibility of using the developed machine also for dressing seeds in an aqueous emulsion of chemicals, the density of which will be close to the density of water, for the proper efficiency of the technological process, the rotation frequency n1 of the rye seed conveyor should be at least 14.2 min-1 using of the leading sprocket with a quantity number of teeth z = 24 pc.