SU1190042A1 - Method of storing milled peat - Google Patents

Abstract

1. METHOD OF STORAGE OF MILLED PEAT, including the formation of a pile on the extraction field and the artificial control of peat moisture in a stack by applying a constant electric field created by immersing an electrode stack, characterized in that, in order to increase the efficiency of peat protection from self-heating, at the same time with a constant electric field, a periodically varying pulsed field is applied. 2. A method according to claim 1, characterized in that the artificial control of peat moisture in a stack is carried out at a voltage gradient of a constant electric field of 1 - 3 V / cm, the amplitude of a voltage gradient of a pulsed field constituting 2-4 voltage gradients of the electric field, the duty cycle of pulses 3-5 and their period of 10-30 minutes. 3. A method according to claim 1, characterized in that I define the zone of the most intensive self-heating of peat and immerse it (O negative electrodes.

Description

The invention relates to peat production, in particular to methods for storing milled peat in piles formed on production fields. The purpose of the invention is to increase the efficiency of protection of peat from self-heating. FIG. 1 shows an example of the method implementation; in fig. 2 is an electric field forming circuit; in fig. 3 is a graphic representation of the electric field created between the electrodes. The storage method for milled peat is as follows. Peat harvested from the fields of production in piles 1 (Fig. I) is periodically monitored for self-heating intensity. Upon detection of hot spots with increased temperature for normal storage conditions, the mobile unit 2 with 3 pole electrodes 4 (-) and 5 {+) mounted on a telescopic boom approaches the hearth and immerses the electrodes in it, the negative electrodes being immersed in the zone of the most intense peat self-heating. . The source of energy for creating an electric field is an alternating voltage generator 6 (Fig. 2) connected to a power shaft of a mobile unit. The voltage from the output of the generator 6 is supplied to the primary winding of the transformer 7. The secondary winding has two outputs: pin 8 for obtaining the initial voltage Vo, which forms a constant electric field, and pin 9 for obtaining a pulse voltage Vu, which generates a pulse electric field. The switching of the leads of the secondary winding is carried out by the contact 10 of the executive relay 11, the winding of which controls the time relay 12 in accordance with the set pulse duty cycle.

Table 1 The voltage from the terminals of the transformer is supplied to the rectifier 13, and from its output, the UEIG is fed to the electrodes. An electric field is formed between the electrodes immersed in the center of self-heating of peat, with a constant Vo and an additional pulse voltage applied to it. Under the influence of an electric field, the moisture from the zone of the positive electrode 5 moves to the zone of the center of intensive self-heating - to the negative electrode 4, moisten this dangerous zone of heated peat in the stack and eliminate the danger of further heating. The imposition of a pulsed electric field on a constant increases the rate of filtration of moisture in peat (moisture transfer) and reduces the time to eliminate hot spots of self-heating. The shape of the voltage applied to the electrodes is shown in FIG. 3, where in the coordinate system the voltage gradient of the electric field () - time (t) graphically depicts the gradient of the AO voltage of the constant electric field, the amplitude AU of the voltage gradient of the pulsed electric field; the magnitude of the excess amplitude of the voltage of a pulsed electric field relative to a constant, the period T of the pulse following; duration t; j pulses and duty cycle C pulses. The self-heating centers are processed with a minimum electric field voltage gradient of 1-3 V / cm providing moisture transfer, the voltage amplitude of the pulsed electric field exceeding a constant 2-4 times, the duty cycle of pulses 3-5 and their period of 10-30 min In tab. Table 1 shows the effect of the electric field voltage gradient on the heating temperature of peat and moisture transfer in the stack.

, ml / min about 3.0 15.0 24.6 33.6 20.5 20.5 20.8 21.1 24.5 33.5 40.5 From the table. As can be seen from Fig. 1, with an increase in the gra-55 voltage gradient, the moisture transfer also increases, having a maximum of 46.5 ml / min with a voltage gradient of 6 V / cm. 42.0 45.6 46.5 39.9 15.0 10.0 47.0 52.0 56.0 However, with an increase in the voltage gradient, in addition to the increase in direct energy consumption, a layer of dry peat forms around the positive electrode

and, as a result, its heating, for example, to 47 ° C at 6 V / cm. The latter causes an intensification of the process of self-heating and leads to an increase in the loss of peat as a result of its physical, biochemical and microbiological transformations.

According to the data obtained, peat with the initial temperature in the stack of 20.5 ° C with a voltage gradient of V / cm and a moisture transfer rate of 15.0–33.6 ml / min provides the most stable temperature of the surrounding peat electrodes 20.8–24.5 ° C practically does not affect the peat self-heating process.

As can be seen from the table. 2, when applying a pulsed field to a constant electric field created between the electrodes, the rate of moisture transfer increases, reaching a maximum of 51.0 ml / min. According to the results of the obtained data, the optimal parameters of the pulsed field — the coefficient of amplitude excess were found. Pulse field voltage relative to constant field voltage and pulse duty cycle, providing the most efficient moisture transfer of 42.0-51.0 ml / min (when processing peat only with a constant electric field, moisture transfer of 15.0-33.6 ml / min, cm Table 1).

When the pulse frequency is 10–30 min, the moisture transfer rate is 48.6–51.0 ml / min, which corresponds to a pressure gradient of 0.5 V / cm and a moisture transfer of 3.0 ml / min. Peat is not subjected to additional heating, but the moisture transfer process it is slow and requires a prolonged exposure of the electric floor to the processing of peat in a pile in the self-heating center.

In tab. Figure 2 shows the data on the efficiency of moisture transfer as a function of the parameters of the pulsed field (per unit of energy expended) at V / cm (data are compared with moisture transfer under the influence of a constant electric field with equal energy expenditure).

table 2

When the amplitude of the voltage gradient of the pulsed field exceeds the constant-field voltage by a factor of 5 or more, the solubility of gases in the filtration flow increases, resulting in an intense release of gas bubbles, which slows down the moisture transfer in the capillary-porous peat structure.

In tab. Figure 3 shows the data characterizing the dependence of moisture transfer on the period of the pulse following a voltage gradient of an electric field of 2 V / cm, a ratio exceeding the amplitude of a pulsed field, and a duty cycle.

Table 3

and the more optimal values of this indicator are given in Table. 2

With a pulse frequency of less than 10 minutes, the moisture transfer rate is small, since the small air bubbles released by the pulsed electro-filtration of moisture in the porous peat structure do not have time to rise up, hindering the moisture transfer process.

With a pulse frequency of more than 30 minutes, the speed of the filtration flow also decreases due to an increase in the effect of the oppositely directed electric field induced by the filtration flow (the Quincke effect).

Divergent electrodes are located at a distance of 0.5-1.5 m from one another.

Since the foci of self-heating peat in the pile in the initial period of their formation do not exceed 0.3-1.0 m, and around them a zone of dried peat with low humidity, which is equal to 0.4-0.6 of the largest diameter of the hearth, is formed, the positive electrodes must be placed outside this zone, which is, for example, for foci of maximum size in the initial period of their formation, the distance

, 5 m - f 0.6 m + (0,, 4) m

 1, 5 m.

where (0,, 4) m is the distance from the outer boundary of the dried peat zone to the peat zone with high humidity.

As the distance between opposite-pole electrodes increases, the effect of moisture transfer decreases or the voltage of the electric field becomes necessary, which, in turn, leads to additional heating of the peat, intensifying the self-heating process.

The additional effect of a pulsed electric field applied to a constant electric field created between the peat-immersed electrodes allows speeding up the moisture transfer process in the milling peat piles and increasing the effectiveness of protecting it from self-heating.

In addition, the pulsed electric field does not cause any significant increase in the temperature of the peat surrounding the electrodes, while achieving equivalent moisture transfer by increasing the constant electric field gradient leads to heating of the peat, which is unacceptable.

FIG. 2

Claims (3)

1. METHOD OF STORAGE OF MILLING PEAT, including the formation of a stack on the extraction field and the artificial regulation of the humidity of peat in the stack by exposure to a constant electric field created by immersion in the headquarters of FIG. 1 linen of electrodes, characterized in that, in order to increase the efficiency of protecting peat from self-heating, a periodically changing pulsed field is applied to the stack simultaneously with the influence of a constant electric field. 2. The method according to π. 1, characterized in that the artificial regulation of the moisture content of peat in the stack is carried out with a voltage gradient of a constant electric field of 1-3 V / cm, an amplitude of a voltage gradient of a pulsed field of 2-4 voltage gradients of a constant electric field, a duty cycle of 3-5 and their period following 10-30 minutes 3. The method according to π. 1, characterized in that the zone of the most intense self-heating of peat is determined and negative electrodes are immersed in it.