RU2321981C1 - Method for desinsection and disinfection of materials of grain origin - Google Patents

Abstract

FIELD: methods for pre-plant processing of grain.

SUBSTANCE: method includes creation of re-circulating gas stream in discharge chamber, injection of UHF energy, creation of plasma in chamber volume and letting material being processed through the chamber in form of free-falling stream. The UHF energy for creation of plasma is injected in impulse or in continuous modes in form of three electromagnetic waves, two of which have orthogonal linear polarization, which is perpendicular to the discharge chamber axis, and third wave has axial component of electromagnetic field, and the material is additionally affected by modulating at least one electromagnetic wave with impulses with frequency of repetition within ultrasonic spectrum. Duration of impulses equals 1-5 microseconds. Also, modulation frequency changes continuously in aforementioned ultrasonic spectrum with period of 0,01-0,02 seconds, and constant electric current is additionally let through plasma equipment.

EFFECT: prevented infection of grain by barn billbug, suppressed bactericide infectiousness and increased germination capacity of grain.

Description

The invention relates to methods for presowing processing of grain, providing a decrease in bacterial infection and increase the germination of grain.

There is a method of presowing treatment of a portion of grain with low pressure gas plasma at a discharge frequency of 1-40 MHz and a power density of not more than 0.003 W / cm for 5-300 s (US Pat. RF No. 2076557 from 1995).

There is also known a method of presowing processing of grain, according to which a portion of the grain is subjected to electromagnetic microwave radiation for 10-60 minutes in cm and mm wavelength ranges (US Pat. RF No. 2083071 from 1997).

There is also known a method of disinsection of grain in a pulsed microwave field with left polarization with a pulse duration of 1-2 μs, a repetition frequency of 200-1000 Hz and an electric field of 1-5 kV / cm (Pat. RF No. 2061350 from 1991).

All these processing methods have low productivity due to the low density of the input energy, and in the method of processing grain with a microwave field at a frequency of 2.745 GHz with a supplied power of 0.9-10 W and exposure 24-26 s (Pat. RF No. 2061351 from 1994 ) the effect is achieved by heating the grain, which often leads to its overheating and loss of germination.

In all methods in which the grain is processed by directional radiation (for example, laser - US Pat. RF No. 1748690 from 1990, in the red and infrared spectral regions - US Pat. No. 2090031 from 1995, ultraviolet - Pat. RF No. 2051551 from 1992), large areas of the grain surface remain untreated due to the shadow.

There is a known method of processing grain, according to which the seeds in a solution of biologically active substances and film formers are subjected to ultrasonic (ultrasound) treatment for 20-40 s, dried in an electromagnetic field and processed in the RF and microwave fields (Pat. RF No. 2051552 from 1992 g.). For processing by this method requires a long time, which determines the low productivity of the method.

The closest prototype of the present invention is a method of disinfection and disinsection of materials of grain origin, including the formation in the discharge chamber of a recycle gas stream, supplying microwave energy, creating plasma in the chamber volume and passing the processed material through the chamber in the form of a freely falling stream (US Pat. RF No. 2112345 from 1997). The processing speed is limited by the possibility of burning grains with an increase in the energy introduced into the discharge.

The technical result of the invention is to increase productivity and increase seed germination.

The essence of the invention lies in the fact that the microwave energy to create a plasma is introduced in a pulsed or continuous mode in the form of three electromagnetic waves, two of which have orthogonal linear polarization perpendicular to the axis of the discharge chamber, and the third wave has an axial component of the electromagnetic field, and additionally affect the material by modulating at least one electromagnetic wave with pulses with a repetition rate selected from the ultrasonic range. In this case, the pulse duration is (1-5) μs.

In addition, the modulation frequency continuously changes in the indicated ultrasonic range with a period of (0.01-0.02) s, and a constant electric current is additionally passed through the plasma formation.

The method is as follows.

Two electromagnetic waves of the H ₁₁ type, the electric field components of which are perpendicular to the axis of the device, and a third wave of the E ₀₁ type, containing the electric field components along all three orts of the Cartesian coordinate system, excite in the discharge chamber. In this case, the maximum of the longitudinal component is on the axis. A discharge is ignited, a microwave plasma discharge is excited in a vortex of the working gas and grain material is supplied. The combined action of all three waves ensures uniform grain processing over the flow cross section.

Additional opportunities to increase the uniformity of grain processing are provided by the organization of polarization rotation by introducing the first two waves from one microwave source with phase shift of the waves or by passing a constant electric current. The introduction of the first two waves from different microwave sources provides polarization rotation by using conventional methods for controlling the phase of electromagnetic waves. In the case when one of the waves is introduced in a continuous mode, the process of plasma deionization in the pause between pulses is substantially slowed down and the level of gas ionization by the time the next pulse arrives is sufficient to excite the plasma. This allows you to increase the pause between pulses while maintaining or increasing the power in the pulse. Since the period of microwave waves is significantly shorter than the passage of grain flow through the working space of the chamber, there is no risk of obtaining an unprocessed product.

The additional transmission of direct electric current is accompanied by an increase in the energy introduced into the discharge. At the same time, the degree of gas ionization is sufficient to excite the plasma with the arrival of the next pulse, and the requirements for the power of microwave sources and the cost of processing the material can be reduced, since microwave energy is much more expensive than direct current energy.

Our studies have shown that the effect of microwave pulses with a sufficiently high energy on the plasma, resulting in its corresponding pulse heating in the energy release volume and its sharp expansion, leads to the appearance of shock waves in the plasma, which have a mechanical effect on the surface of the grains, eliminating internal infection and causing additional activation of grains in the entire volume of grain filling. The effect is most pronounced when the pulse repetition rate changes in the ultrasonic range, since at some frequencies there is a resonant interaction of sound waves with the grains, improving the transformation of the energy of sound waves into the energy dissipated in the grains, and their activation. In addition, the disinfecting effect of ultrasonic vibrations is known, which always improves the germination of grain, while a purely plasma effect is carried out only on the surface layer of the grains.

The accepted range of ultrasonic vibrations is (20-100) kHz, and the pulse repetition rate is selected from this range. The shock wave is created by the leading edge of the microwave pulse, so an increase in its duration over 5 μs only heats the grains and therefore is not practical. The minimum duration of microwave pulses of 1 μs is determined by the capabilities of microwave equipment (the probability of increasing the amplitude of the pulse to the maximum). The period of change in the frequency of modulation of microwave pulses is dictated by the time of flight of the grains (it should exceed the period of change of the frequency of modulation) and for the actual size of the equipment is (0.01-0.02) s.

It has been established that at least 20% of the microwave energy supplied to the plasma goes into the energy of sound waves; therefore, the additional effect of grain activation is significant. An experimental check showed the almost complete elimination of external and internal contamination of grain with barn weevil, the suppression of bactericidal infection and an increase in productivity by 20-30%.

Claims (3)

1. The method of disinsection and disinfection of materials of grain origin, including the formation in the discharge chamber of a recirculating gas stream, adding microwave energy, creating plasma in the chamber volume and passing through the chamber the processed material in the form of a freely incident stream, characterized in that the microwave energy is introduced into pulsed or continuous modes by using two electromagnetic waves with orthogonal linear polarization perpendicular to the axis of the discharge chamber, and a third electromagnetic wave with axial component of the electric field and additionally affect the material by modulating at least one electromagnetic wave with pulses with a repetition rate selected from the ultrasonic range with a pulse duration of 1-5 μs. 2. The method according to claim 1, characterized in that the modulation frequency continuously changes with a period of 0.01-0.02 s. 3. The method according to any one of claims 1 or 2, characterized in that a constant electric current is additionally passed through the plasma formation.