RU2029715C1 - Method of conveying grainy material by aerochute with inclined gas-distributing grid - Google Patents

Abstract

FIELD: transportation of materials. SUBSTANCE: method involves feeding gas flow at a rate of W_α ≅ W ≅ W_o/cosα , W_α- where

is minimum allowable value of rate, at which conveyance of material is conducted, W_o is speed at the initial stage of fluidization process with aerochute inclination angle of α = 0; α^*- is angle of rest of grainy material; K₁, K₂ is permeability coefficient of grainy material. EFFECT: reduced specific power consumption and consumption of aerating gas, provision for usage of low-aerodynamic resistance grids. 1 dwg

Description

 The invention relates to methods for transporting granular granular materials in aerial chutes and can be used in various industries.

 Known methods of transporting granular materials in a gas suspension flow at gas velocities comparable to the speeds of particles of transported material [1], as well as a method of transporting granular material in a fluidized channel achieved by aeration of air under a layer [1, p. 161], fluidized material moves under the action of gravity and gas momentum. These methods are characterized by relatively large energy consumption for transportation.

 A known method of transporting granular material in an aeration channel, which consists in fluidization and its movement [1, p. 8]. With this method, the material flows like a liquid in a uniformly fluidized bed. However, this requires relatively large energy costs, since transportation is carried out at a gas aeration rate equal to or greater than the rate of onset of fluidization.

 The aim of the invention is to reduce energy consumption.

This goal is achieved by the fact that the transportation of granular material is carried out in a dense layer at a gas aeration rate in the range from ω _{α the} minimum allowable speed at which transportation is possible to the fluidization start speed ω _o / cosα.

= -K

-K

, где К₁ и К₂ - коэффициенты проницаемости зернистого материала, величина ω_αрассчитывается из выражения (при этом К₂ ≠0) [3]:
ω_α= -

+

, (1) где α- угол наклона аэрожелоба к горизонту; ω_o- скорость начала псевдоожижения при α= 0; α*- угол естественного откоса зернистого материала.In a commonly used conveying method, a uniformly fluidized bed moves. If you conduct a rigorous analysis of the conditions under which the movement of the granular material begins in the aerial groove, you will find that the layer can move in the dense state. From the equilibrium conditions for an even layer of granular material on an inclined plane, or rather, from the equality of rolling force and friction force acting per unit volume of the filtered material, we can obtain a relationship connecting the velocity of fluidization of the granular material and the minimum value ω _α of the gas filtration rate in the layer, which transportation is possible. At a gas velocity ω _α , a shift begins — the material creeps down. If gas filtration occurs according to the law [2, c.293]

= -K

-K

where K ₁ and K ₂ are the permeability coefficients of the granular material, the value of ω _{α is} calculated from the expression (with K ₂ ≠ 0) [3]:
ω _α = -

+

, (1) where α is the angle of inclination of the air duct to the horizon; ω _o is the velocity of the beginning of fluidization at α = 0; α * is the angle of repose of the granular material.

The fluidization of the granular material in the aeroguite occurs at a gas velocity at which the weight force is balanced by the pressure drop in the layer and is determined by the ratio [3]:
ω _oα = ω _o / cosα (2)
During aeration of the gas at a speed less _{than the} value of ω _oα , the particles rely on each other, i.e. not fluidized. The layer is in a dense state. Its stability is not violated. For the same reason, transportation can be carried out at a very small (theoretically zero) value of the aerodynamic drag of the gas distribution grid. The latter circumstance allows reducing energy costs for transportation.

The drawing shows the ratio of the values of ω _α / ω _o calculated according to the formula (1), in the aerial groove 2 m long, 0.1 m wide.

1 - particles of electrocorundum 120 μm, ω _o = 0,051 m / s;
2 - particles of electrocorundum 200 μm, ω _o = 0,100 m / s;
3 - glass balls 750 μm, ω _o = = 0.400 m / s;
4 - river sand 400 μm, ω _o = 0.350 m / s;
5 - ash Kuznetsk coal 100 μm, ω _o = = 0.022 m / s, gas distribution grid - fabric type "belting".

 The application of the proposed method of transporting granular material in an aeroglove allows, in comparison with existing methods, to reduce the specific energy consumption for transportation, to reduce the consumption of aerating gas, to use gas distribution grids of very low aerodynamic drag.

Claims (1)

METHOD FOR TRANSPORTING GRAIN MATERIAL IN AN INCLINED GAS DISTRIBUTION AEROGRAPHIC GRILL, which consists in the fact that the gas is exposed to a gas flow directed at an angle to the vertical, which is equal to the gas distribution angle, which has a different flow rate, which with speed
W _α ≅ W ≅ W _o / cosα,

where W _α is the minimum permissible value of speed at which transportation is possible;
W ₀ - velocity of the beginning of fluidization at a = 0; ;
α ^* is the angle of repose of the granular material;
K ₁ and K ₂ - permeability coefficients of the granular material.

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