RU2569541C1 - Drying drum - Google Patents

Abstract

FIELD: machine building.

SUBSTANCE: drying drum has lifting-blade nozzle, installed in the casing, and made in form of peripheral radial blades equipped with two paddles, located at angles to the blade depending on angle of natural slope of wet loose material varying along the drum length depending on moisture change of the dried material.

EFFECT: achievement of maximum efficiency of drying in the dry drum due to complete implementation of potential of the drum paddles adapted to angle of natural slope of the loose material.

2 cl, 2 dwg

Description

The invention relates to a technique for drying bulk materials with mixing of the dried material under the action of rotation of the drum and can be used in various fields of the national economy, where drying or other processing of bulk material at elevated temperatures is necessary.

Known dryer drum with a peripheral blade nozzle, consisting of a housing with blades made with a profile built in polar coordinates according to the equation

where α is the maximum value of the radius, m; φ is the angle of rotation of the scapula. Moreover, the blades are oriented relative to the drum body in such a way that the straight line drawn through the axis of rotation of the drum and the origin of the profile of the blade has an angle tangent to the profile of the blade made from the origin equal to the angle of repose of the bulk material, from the origin of the profile to the point touching the profile of the blade with the drum body in a counterclockwise direction, the blade has an open area. A drum dryer with blades of the proposed profile ensures uniform distribution of bulk material throughout the entire inner volume of the drum and intensifies the drying process due to the maximum number of particles in suspension (see RF patent No. 2204772, IPC F26B 11/04, publ. 05.20.2003) .

A known dryer drum nozzle containing blades having a concave profile made along a radius vector r _n drawn from a pole lying on the free edge of the blade and changing according to the law

where r _max is the maximum radius vector located on a straight line passing through the pole, perpendicular to the surface of the material lying on the blades at an angle of repose at the moment the pole passes through the horizontal diameter of the drum;

α = 90 / Ν is the angle defining the interval for constructing the profile of the blade;

N is the number of construction intervals;

n is the sequence number of the interval

(see RF patent No. 1262243, IPC F26B 25/16, publ. 07.10.86).

Closest to the claimed device is a drying drum equipped with a lifting-blade nozzle installed in the housing and made in the form of peripheral radial blades equipped with two blades located at different angles to the blade, depending on the angle of repose of the bulk material, and made with the following parameters:

β = 2.95 ÷ 3.05φ; α = 3.25 ÷ 3.35φ; in = 2 a = 0,050 ÷ 0,075D,

where β is the angle of inclination of the larger blades to the base of the blade;

α is the angle of inclination of the smaller blades to the base of the blade;

φ is the angle of repose of the bulk material;

in - the width of the larger scapula;

a is the width of the smaller scapula;

D is the diameter of the dryer body.

The shape of the blade ensures the formation in the drying zone along the cross-section of the drum dryer a denser and more uniform curtain of material on the path of the heat agent, which significantly intensifies the heat transfer process and leads to an increase in dryer productivity and fuel economy (see RF patent No. 2444686, IPC F26B 11 / 06, published March 10, 2012).

The disadvantages of the first two devices (patents No. 2204772 and No. 1262243) are the complicated process of calculation and design, as well as the presence of rounded parts, which must be performed with considerable accuracy, which greatly complicates and increases the cost of their manufacture, especially provided that a sufficiently thick and high-quality metal is used . A common drawback of all of the above technical solutions is that their design does not take into account the increase in the angle of repose of the initial wet bulk material and the change in this value during the drying process.

It is known that the angle of repose of wet bulk material can significantly exceed the value of the angle of repose of air-dry bulk material. In addition, the angle of repose of the dried material will change during drying due to changes in its moisture content. For this reason, blades designed for dry bulk material will satisfactorily cope with their task only at the end of the drying process, in the last part of the drum. At the beginning and in the middle of the drum, the potential of the blades will not be realized, since the angle of repose of the material will be overestimated, it will fall off later, and a zone will appear in the cross section of the drum that is not covered by a curtain of crumbling material.

In this case, the thermal agent passes along the path of least resistance, that is, through the free from the material part of the cross section of the drum. This leads to the following negative consequences:

- sharply decreases the amount of heat agent passing through the cross section of the drum, covered by a curtain of falling material, which leads to a decrease in the amount of heat received by the dried material;

- due to a decrease in the cross-sectional area of the heat agent flow, its speed increases. This, in turn, leads to an increase in material entrainment;

- heat not given to the dried material at the outlet of the drum overheats the output manifold, chimneys and prematurely destroys the gas duct seals.

The technical result of the invention is to achieve maximum drying efficiency in a drying drum due to the full realization of the potential of the drum blades, adapted to the angle of repose of the bulk material.

The result is achieved in that a drying drum comprising a housing, a lifting-blade nozzle installed in the housing and made in the form of peripheral radial blades equipped with two blades located at different angles to the blade depending on the angle of repose of the bulk material, is characterized in that the blades are made with the following parameters:

β = φ _dry + 45 + ω * B, deg.,

α = φ _dry + 90 + ω * B, deg.,

where β is the angle of inclination of the blades installed closer to the surface of the drum, relative to the blade;

α is the angle of inclination of the blades located further from the surface of the drum, relative to the blade;

ω is the moisture content of the test bulk material,%;

φ _dry - the angle of repose of dry bulk material, equal to the angle of internal friction of the bulk material, deg .;

B is a coefficient reflecting the dependence of the angle of repose of the bulk material on its moisture content and established experimentally for each bulk material.

The drying drum is also characterized in that the blades are made with an angle of inclination relative to the blades, varying along the length of the drum, depending on the change in humidity of the dried material.

In FIG. 1 shows a cross section of a drying drum, FIG. 2 is an enlarged image of one blade.

The device consists of blades 1 and 2 mounted on the blades 3, which are fixed at the same distance from each other around the perimeter of the drum body 4.

The result is achieved by the fact that:

1) the angle of inclination of the blades is not selected in accordance with the angle of repose of the air-dry bulk material to be dried, but in accordance with the angle of repose of the wet material, determined by the expression

where φ _rh - a static angle of repose of moist bulk material, deg;

ω is the moisture content of the test bulk material,%;

φ _dry - the angle of repose of the dry bulk material, equal to the angle of internal friction of the bulk material, deg;

B is a coefficient reflecting the dependence of the angle of repose of the bulk material on its moisture content and established experimentally for each bulk material;

2) since the humidity of the material changes during drying, the drum has several sets of blades located along the length of the drum with different slope of the blades, determined for different humidity of the material, which varies according to the kinetics of drying of bulk material, determined experimentally.

The angle of inclination of the blades 1 to the blades 3 is equal

The angle of inclination of the blades 2 to the blades 3 is equal

The device operates as follows.

The dried material is loaded into the lower part of the drum body 4, when the drum rotates counterclockwise, the blade 3 is loaded with material that is on both blades. In the upper part of the drum, the material begins to pour from the blade 2. By the time of complete unloading of the blade 2 (at the upper point of the position of the blade H), material begins to pour from the blade 1. Thus, the blade 2 provides a uniform curtain of material in one half of the drum, and the blade 1 - in another.

Claims (2)

1. A drying drum containing a housing, a lifting-blade nozzle installed in the housing and made in the form of peripheral radial blades equipped with two blades located at different angles to the blade depending on the angle of repose of the bulk material, characterized in that the blades are made with following parameters:
β = φ _dry + 45 + ω * B, deg.,
α = φ _dry + 90 + ω * B, deg.,
where β is the angle of inclination of the blades installed closer to the surface of the drum, relative to the blade;
α is the angle of inclination of the blades located further from the surface of the drum, relative to the blade;
ω is the moisture content of the test bulk material,%;
φ _dry - the angle of repose of dry bulk material, equal to the angle of internal friction of the bulk material, deg .;
B is a coefficient reflecting the dependence of the angle of repose of the bulk material on its moisture content and established experimentally for each bulk material. 2. A drying drum according to claim 1, characterized in that the blades are made with an angle of inclination relative to the blades, varying along the length of the drum, depending on the change in humidity of the dried material.

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