SU1730519A1 - Dryer of fibrous materials - Google Patents

Abstract

The invention relates to a drying technique and can be used primarily in the oil and fat industry for drying cotton cotton seeds, as well as other granular fibrous materials. The purpose of the invention is to improve the quality of drying by intensifying heat transfer while reducing energy consumption. To improve the hydrodynamic environment in the layer of granular fibrous material, the coolant is supplied through the gas distribution device and additionally a hydrodynamic jet is introduced into the layer through a nozzle installed in the center of the apparatus, which contributes to the homogeneous expansion of the layer, the intensification of interfacial interaction and heat and mass transfer in the layer of granular fiber .1 hp ff, 2 ill. V ё

Description

The invention relates to drying and can be used in the drying of granular fibrous materials (computers), in particular cotton seeds.

A known dryer for granular fibrous materials, which is a cylindrical chamber with an auger inside, where the material is agitated by an auger, and the coolant is supplied through a perforated bottom of the chamber. The dryer contains a horizontal cylindrical chamber, a perforated bottom, a screw with perforated blades with a decreasing spacing of turns in the direction of movement of the material being dried, and an inner jacket placed at a ZO - 35% of the parameter area, where there are also loading and unloading devices and exhaust pipes. The inner shirt is connected to the hot spring.

air, and external to the source of coolant (steam).

The dryer works as follows: wet cotton seeds with a loading device enter the chamber, where the auger moves in the direction of the unloading device. Steam entering the outer jacket heats the air supplied to the jacket. The hot air passes through the perforated bottom and dries the cotton seeds. Humid air is expelled from the chamber through the air vent. The decreasing pitch of the screw turns makes it possible to increase the filling of the chamber with seeds, and the perforation on the blade of the screw augers the intensity of heat and mass transfer.

The disadvantages of this dryer are large energy consumption, the heterogeneity of the layer of the material being dried,

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as in the screw apparatus, when cotton seeds are dried, the filling ratio of the apparatus is low and, due to adhesion between the fibers, conglomerates are formed on the front (working) side of the screw and the free area behind the screw, and heat carrier slip occurs, i.e. There is a negative effect of layer heterogeneity on the intensity of the interfacial interaction.

The known dryer for bulk materials, which is a sealed toroidal chamber, has a loading device that provides loading and dosing of the material, a discharge device in the form of a flashing valve that opens under the influence of a certain weight of the bulk material in it, as well as a suction nozzle. There are several sections of conductors on the torus body to create a high-frequency electromagnetic field inside the chamber. Inside the chamber there is a system of interconnected sections. The sections are made in the form of perforated partitions and are fixed on a ring passing along the inner side of the torus and having a gear connection with the electric drive.

 To ensure the free movement of sections within the torus, the support rings of the sections rest on roller bearings. The dryer works as follows: wet material is fed through the loading unit into sections inside the torus. Moving along with the sections, the wet material enters the high-frequency field created by the high-frequency currents passing through the conductors located on the torus body. Moisture released from the material is removed through the perforated walls of the sections with the help of a vacuum pump, which sucks air from the internal cavity of the torc and the spaces between the sections. The material, dried as a result of normalized periodic exposure to a high-frequency field, subsequently moves into the zone of the discharge device and is removed from the chamber through the flashing valve under the influence of its own weight.

The disadvantages of this dryer are cumbersome, the presence of mechanically rubbing nodes, significant energy costs, both for moving and heating the material by high-frequency currents, as well as low productivity due to the slow removal of moisture from the poorly displaced material mass.

Closest to the present invention is a dryer for fibrous materials, containing rectangular sections for a fluidized bed, divided into drying and cooling sections by means of removable partitions, each section having an individual coolant supply. A gas distribution grid is located in the lower part of the chamber, and a rotating horizontal shaft with radial pegs is installed above it. The shaft is hollow and equipped with nozzles for

0 moistening of the material with the steam-water mixture in the drying zone.

If necessary, the dryer can operate without the inclusion of nozzles and have any necessary number of sections.

5 A horizontal shaft with radial pegs is designed to destroy stagnant zones and channels in the layer of granular fibrous material.

The disadvantages of this dryer are cumbersome, multisectional construction, the presence of a disintegrant, i.e. horizontal shaft with knobs, which is the cause of uneven flow of the coolant in the layer and increases

5 hydraulic resistance of the computer layer, as well as prevents effective contact of the coolant with the material.

The purpose of the invention is to increase the efficiency of the drying process by intensifying heat exchange while reducing energy consumption.

The goal is achieved by the fact that the gas distribution node has

5, an additional gas distribution grid, a nozzle between the latter and a hydrodynamic active jet of a heat transfer fluid located above the nozzle and an additional

0 with a grille nozzle, and the nozzle has the shape of a rhomboloid, made so that the ratio of its height to diameter is 1.

Application of gas distribution

5 devices with an optimal living cross section of a perforated lattice in combination with a hydrodynamically active jet and a rhomboloid nozzle increase the volume of the stationary layer of a particulate fiber 1.8–2 times, increase the intensity of interfacial interaction, drastically reduce channelization in the granular layer -fibrous material, hydraulic reduction

5 resistance of the layer and uniform drying of the seeds at a lower flow rate of the coolant.

There are a number of studies on the drying of cotton seeds in a fluidized bed, which is characterized by intense heat and mass transfer. But the use of the principle of fluidization is impractical to use when drying granular fibrous materials, such as oilseeds of cotton. Fluidization of fluidized granular material is explained by an increase in the rate of the onset of fluidization with an increase in pubescence from 1.2 m / s for Op 0% to 2.2 m / s at Op 12.6%.

As it is known, fluidization (stable) is carried out with the number of fluidization, respectively, and air consumption increases with increasing pubescence.

When drying in a fixed bed, i.e. in convective drying, high energy costs and the processes occurring under these conditions are ineffective. Filtration processes require tremendous coolant flow rates for drying wet granular materials to final moisture.

Compared with the drying method in the fluidized bed apparatus, where the uniformity of the layer is provided by a rotating horizontal shaft with radial pegs at the speed of the coolant W WKp, the proposed device allows to intensify the process of heat and mass transfer and to improve the hydrodynamic environment at W WKp.

Figure 1 schematically shows the proposed device; Figure 2-node I in FIG. one.

The device for drying cotton seeds (figure 1) consists of a cone-cylinder of a black working chamber 1 with a taper of 17 and a base diameter of 150 mm, a gas distribution chamber 2, an upper 3 and lower 4 gas distribution grids, a nozzle 5, a nozzle, rhomboloid 6, pipe 7 for sampling and loading pipe 8.

Hot air into the working chamber 1 is delivered through the gas distribution chamber 2, where perforated grilles 3 and 4 are installed, located one above the other at a distance of 100 mm. The upper gas distribution grill 3 has a living section of 4% and a hole diameter of 3 mm, and the lower grill 4 has a living section of 16% and a hole diameter of 10 mm.

In addition, a stream of heat transfer fluid is fed through a nozzle 5 installed in the center of the gas distribution device into a layer of granular fibrous material. To evenly distribute the active jet above the nozzle at a distance of 5 mm over 3 rods fixed at an angle of 120 ° to each

a rhomboloid 6 is installed relative to the other. The apparatus also contains a loading nozzle 8 and a nozzle 7 for sampling.

The coolant enters the drying chamber through the gas distribution chamber, where, to level the velocity profile over the cross section of the apparatus and to introduce the coolant evenly into the layer of granular fibrous material, two perforated grids are installed 100 mm from each other. In addition, a hydrodynamically active jet of heat transfer fluid is fed into the layer through the nozzle 5, which is dissected by rhomboloid 6 and evenly distributed over the cross section of the apparatus.

The proposed installation works as follows.

Wet cotton seeds enter the bottom of the drying chamber through the loading nozzle and are dried with hot air supplied through gas distribution grids 3 and 4. A rhomboloid is installed to dissect the jet above the nozzle, the diameter of which varies from 12 to 20 mm. 10, the size of which varied in the range H / D 0.5 - -1.7. Under the condition H D, a stagnant zone forms in the layer above the rhomboloid due to the uneven distribution of the flow of heat-transfer fluid. If, the main part of the flow occurs through the central part of the apparatus, without capturing the particle in the periphery, which leads to the formation of channels under the condition On 2%, i.e. for cotton seeds, we obtain optimal hydrodynamic regimes of H / D 50/50 mm.

Thus, using the invention, the drying uniformity is improved, the formation of stagnant zones in the layer of granular fiber material is prevented, and the operational reliability of the installation is increased.

Example 1. A layer of 108F cotton, with a fiber content of 12.6% and an initial moisture content of 18% is placed on the gas distribution device. The specific load is 65 kg / m, and through the distribution grid the material layer is blown with hot air with a temperature of 105 ° C. at a speed of VV of 2.0 m / s, the number of fluidization is K 0.9. The expansion rate of the fixed bed is V / V0 1.6 with a porosity of Ј 0.77. Drying time 7 minutes, final moisture content of cotton seeds U 10%.

EXAMPLE 2. Drying conditions are similar to those of Example 1. The total flow velocity is 1 m / s. Additionally, a high-temperature jet is introduced through a nozzle with a diameter of 16 mm, the fictitious speed of which is W 1 m / s. The dimensions of the rhomboloid mounted above the nozzle were H / D 1 (H / D 50/50 mm) at, 8, Final humidity, U - 9.5%, drying time 4.8 minutes.

Example 3: The conditions are the same as those of example 2. The diameter of the nozzle is 12 mm, the degree of expansion V / V0 is 1.40. Drying time 5.6 minutes, final moisture U 9.8%.

EXAMPLE 4 Drying conditions are similar to those of Example 2, the rhomboloid dimensions were H / D - 50/30 mm, the expansion ratio V / V0 is 1.4, the drying time is b min, and the final moisture content is 10%.

EXAMPLE 5 The drying conditions are similar to those of Example 2. The rhomboloid dimensions were H / O 50/100 mm, the expansion degree of the V / V0 layer was 1.3, the drying time was 6.2 minutes, and the final humidity was U 10 , 2%.

Claims (2)

1. Dryer for fibrous materials, mainly cotton seeds, including a fluidized bed chamber with coolant outlet pipes, a gas distribution unit located in the chamber, having a gas distribution grid, and a coolant supply pipe, characterized in that, in order to improve the quality of drying by intensifying heat exchange while reducing energy consumption, it is equipped with under the main additional gas distribution grid, a nozzle for supplying a hydrodynamically active jet of heat-transfer fluid, fixed between the main and additional gas distribution - gratings, and a nozzle placed above the nozzle and an additional grate for uniform distribution of the hydrodynamic jet of the heat transfer medium over the cross section of the chamber. 2. Dryer according to claim 1, characterized in that the nozzle is made in the form of a rhomboloid so that its height-to-diameter ratio is 1.  Ґig.4 FIG. 2