SU1294849A1 - Method for drying pellets - Google Patents

Abstract

The invention relates to ferrous metallurgy, in particular to the preparation of iron ore raw materials, namely the production of pellets. The purpose of the invention is to increase the productivity of the roasting machine. The raw pellets 1 are fed to the roller stacker 2 and due to the rotation of the rollers are evenly distributed across the width of the burning carriage 3 and form layer 4. Waveguides 6 of ultrasonic vibrations with piezoelectric transducers 7 are installed on the end of the layer and connected to generator 8 of ultrasonic vibrations . Directly under layer 4 between the mountain drying zone 9 and roller roller 2, an aspiration hood 10 is installed to remove the aerosol moisture. The generator 8 operates in the mode of continuous radiation of ultrasonic waves, which, passing over the surface and the material of the 4th layer of the layer, involve in the ultrasonic vibrations free and pillar moisture, as a result of which it goes into an aerosol state. Inter-breed moisture is removed with aspiration air through cap 10. Aerosol moisture containing in the pores of the pellets in the drying zone 9 is removed. The invention allows to increase the degree of moisture removal by 15-18% and reduce the alkali content of the class of 5 mm by 3-9%. 2 silt, 3 tab. (About with with 4iiik 00 4;; about

Description

I129

The invention relates to ferrous metallurgy and can be used in the production of pellets.

The aim of the invention is to increase the productivity of the roasting machine.

FIG. 1 shows a schematic diagram for the implementation of the proposed method of ultrasonic drying; Fig. 2 is a schematic diagram for the implementation of the proposed method of ultrasonic drying at the same time as heating it up.

The method is carried out as follows.

The raw pellets 1 are fed to a roller stacker 2 tons by rotating the rollers are evenly distributed across the width of the burning carriage 3 and forming a layer 4. Waveguides 6 of ultrasonic vibrations with piezoelectric transducers 7 and a high quality roller are mounted on the supports 5. Ush traznukovyh oscillations are used by generators, serially produced by industry. The frequency of the F of the high frequency oscillations is set in the range of 250–350 kHz. When the ultrasound frequency is less than 250 kHz, the average size of the aerosol particles increases, their lifetime and the surface of the aerosol particles decreases. As a result, the degree of coagulation of the formed aerosol on the surface of the toes increases 10 or more times with the formation of free moisture, which prevents the intensive aspiration of the moisture by the aspiration system. With a higher ultrasound frequency (over 350 kHz), the depth of ultrasonic penetration of waves in the outer layer is significantly reduced; as a result, the degree of moisture removal at the boundaries of the layer decreases, in order to increase the

They are connected to the ultrasound generator 8 which requires the installation of a large

out vibrations. Directly above layer 4, between the mountain drying zone 9 and roller roller 2, there is an aspiration hood 10 for removing aerosol moisture.

The generator 8 operates in the mode of continuous emission of ultrasonic waves. Due to the high humidity and all-round pressure inside the layer 4, pressing forces of 8-10 N are generated, which create reliable contact between the waveguide 6 and the pellets of layer 4. The waveguide 6 is a conductor of longitudinal, transverse

and surface waves, which pass 40 layers. The filtration rate of aspiration over the surface and the material of the layer 4 of the pellets involves free and Tsapillary moisture contained on the surface and in the capillaries of the oatsha in the ultrasonic vibrations, as a result of which it becomes aerosolized. Moisture is removed by aspiration air through cap 10. Aerosol moisture, containing in the pores around 10, in the drying zone 9 of the kiln, is removed by the convective flow of the coolant.

The method of ultrasound imaging can be carried out simultaneously with the heating of the window (Fig. 2) on: - a clone lattice 11 with blowing air-gas jets 12 with a temperature of 200-450 C. Ultrasonic processing is carried out simultaneously with the indicated

ku and ud; I1 (AI (achroso r. yis of moisture ail.pogichis rnociifiy hearing of the bases of iologrev (iKaTi.iiiuM i.

In the quality of energy consumption of the oscillating oscillations, generators produced by industry are used. The frequency of the F of the high frequency oscillations is set in the range of 250-350 kHz. When the ultrasound frequency is less than 250 kHz, the average size of the aerosol particles increases, their lifetime and the surface of the aerosol particles decreases. As a result, the degree of coagulation of the formed aerosol on the surface of the pellets and 10 or more times with the formation of free moisture interferes with intensive moisture removal with an aspiration system. With a higher ultrasound frequency (over 350 kHz), the depth of the ultrasonic penetration of waves in the surrounding layer is significantly reduced; as a result, the degree of moisture removal at the boundaries of the layer decreases, in order to increase the

which requires the installation of a large

the number of waveguides (more than 15), which significantly complicates the technical implementation of the method. The optimum frequency range of ultrasound is the range of 250-350 kHz, which ensures effective transfer of moisture to the aerosol state without coagulation during the aspiration removal time, which allows to create

particles with a size of 12–17 µm, most efficiently removed by aspirating air, do with a small number of waveguides (2-3 pcs.) and increase the degree of moisture removal at the boundaries

50

The air volume is set according to the Reynolds number in the range of 20-50.

The lower limit of the filtration rate is due to the fact that below this rate () the aerosol stays in the pellet layer significantly increases and the aerosol becomes significantly longer (1.8-2.5 min), so the aerosol particles condense in the cold pellets of the upper layer and there is a waterlogging of these sections of the layer.

With the filtration rate of aspiration air Re750, there is a sharp increase in the speed of movement of aerosol particles, which causes a strong dynamic coagulation of moisture on the surface of the air and excessive moisture, gdr (immedi cate (1 upper h)), as well as in this hydraulics in the region, the capture coefficient of the α particles by the pellets of the layer significantly increases.

With optimum aspirated air filtration parameters (Re 20-50), the life of the aerosol is close in magnitude to the time the aerosol is in the pellet layer (1.5-2.2 min), so the aerosol has time to be removed from the pellet without noticeable signs of coagulation. Moreover, the capture coefficient of aerosol particles by the pellets of the layer is significantly lower (1.15-1.2), while the average moisture removal interval of the top layer is 1.4-1.6%, and the bottom layer is 1.9-2.0 abs. .%.

The speed of the aspiration air is controlled by standard flow meters and controlled by throttling equipment and a liquid-filling device. The aspiration air temperature is determined by standard liquid thermometers. The kinematic viscosity of the aerosol corresponds to a certain temperature. Knowing the bulk density and true density of the pellets, the average r-hydraulic diameter for the aerosol passage and the Reay Nolds number are determined.

The method of drying by ultrasound is carried out under the following conditions: the degree of moisture removal in relation to the known 100

Decrease in the content of class trifles - 5 mm in relation to the known

Increase in roasting machine productivity in relation to the known,%

x: the specific productivity of the calcining conveyor machine is 0.85, the moisture content of the pellets is 10%, the porosity of the pellets is 30%, the porosity of the layer is 0.38,

bulk density 1.98 t / m bed height 0.1 m, layer height 0.35 m, diameter of 10.33 m thick, belt speed 12 m / min, ambient temperature 10-20 C.

The obtained data are presented in table 1 - 3.

The invention provides an increase in moisture removal by 15–18 rel.%, A decrease in the content of fines of the class - 5 mm by 3–9 rel.% And a increase in productivity of the roasting machine by 7–9 abs.%.

20 f

Formula Fig.

The method of drying is made using the laying of raw materials made of roller. the stacker, pre-drying, final drying of the layer by filtration of the coolant through it, characterized in that, in order to improve the performance of the roasting machine, the preliminary drying is carried out with coolant in the laminar flow mode with a Reynolds number of 20 to 50 and simultaneously processing the layer with ultrasound at a frequency of 250 - 350 kHz.

Table 1

115

116

118

Ultrasonic Destruction Area

-3

-five

-9

+20

101 107 108 109

Aerosol condition

The ratio of the mass of the enlarged aerosol to the initial mass

The penetration depth of ultrasonic vibrations, m

The average size of aerosol particles, microns

The lifetime of the aerosol particles, min

Note. According to a known method, moisture is in a free and capillary state.

Table3

The coefficient of capture of aerosol particles pellets

The residence time of the aerosol in the layer of pellets, min

Humidity okatshey,%, at the depth of the layer, m

Note By the known method, the moisture content of the pellets is 10%

and distributed evenly over the layer of pellets.

T h 2

Significant pkpazatel with chls.-tote ultra. avukoryh ko.nebyaniy, to c

200 230 300 350

400

AND)

1.11

0.90,8

0.3 0.3 0.25 0.2 0.05

40

12

3.8 2,52,01,81,3

1.05 1.15 1.18 1.2 1.50

2.2 1.8 1.5 1.0

fPtie.Z

Editor N.Egorova

Compiled by A. Blianyukov

Tehred L.Oleynik Proofreader T.Kolb

Order 56A / 28 Circulation 605Subscription

VNIIPI USSR State Committee

for inventions and discoveries 113035, Moscow, Zh-35, Raushsk nab., 4/5

Production and printing company, Uzhgorod, Projecto st., 4

Claims (1)

Claim A method for drying pellets, comprising stacking raw pellets with a roller. stacker, pre-drying, final drying of the layer by filtering coolant through it, characterized in that, in order to increase the productivity of the roasting machine, preliminary drying is carried out by the coolant in the laminar flow mode with a Reynolds number of 20-50 and simultaneous processing of the <layer with ultrasound at a frequency of 250 350 kHz. Table! Technical and economic According to The value of the indicator at the intensity parameters new way (without ultra- ultrasonic vibrations, W / cm ² Ί -I ----- | ----- 1 ------------- sound) <, 0.1 0.3 0.4 0.6 1 0.8 The degree of moisture removal in relation to sto 100 102 115 1 16 118 The area of ultrasonic destruction The reduction in the content of little things in the class is 5 mm in relation to the known 0 0 -3 -5 -9 +20 The increase in productivity of the roasting machine in relation to the known,% 100 101 107 108 109 'H a b faces 2 Aerosol indicator The value of the indicator at an ultra frequency. sound vibration conditions, kHz 200 | 250 ' 300 3 50 400 The ratio of the mass of the enlarged aerosol to the initial mass 10 M 1 0.9 0.8 The penetration depth of ultrasonic vibrations, m 0.3 0.3 0.25 0.2 0.05 The average size of aerosol particles, microns 40 17 fifteen 12 9 Life time of aerosol particles, min 3.8 2,5 2.0 18 1.3 Note. According to the known method, moisture is in a free and capillary state. T table Z Aerosol state parameters Parameter value at Reynolds number Aerosol capture coefficient particle pellets 1.05 1.15 1.18 1,2 1,50 The time spent by the aerosol pellets, min in the layer 6 2.2 1.8 1,5 1,0 The humidity of the pellets,%, per layer, m θ the depth 11.5 8.7 8.5 8.6 fifteen 0.1 9.5 8.3 8.4 8.3 10.5 0.2 9.0 8.2 8.2 8.2 8.5 oh s 8.5 8.1 8.1 8.1 8.3 0.4 8.3 8.1 8.1 8.0 8.0 Note. According to the known method, the moisture content of the pellets is 10% and distributed evenly over the layer of pellets. 1 2948 · ν.)