RU2189931C2 - Method of transportation of high concentration loose materials in gas mixture - Google Patents

Abstract

FIELD: pneumatic transportation. SUBSTANCE: proposed method of loose material transportation includes delivery of compressed gas through branch pipe into chamber feeder for aerating loose material with this gas, additional supply of gas flows spaced over length of transportation pipeline through activators with turning of lows at angle and with lead of helix to provide helical motion of material. Compressed gas is delivered into chamber feeder is swirled state through said branch pipe with possibility of swirling material-and-gas mixture and delivery of swirled mixture into transportation pipeline in which helical motion of material formed at transportation along pipeline is maintained by delivery of said flows at angle and with lead equal to parameters of said helical motion of material. EFFECT: reduced power consumption. 2 dwg

Description

 The invention relates to a method for pneumatically conveying bulk materials with a high concentration and a reduced rate of material-gas mixture.

 A known method of transporting bulk materials, which consists in the fact that the bulk material transported by a blower pneumatic conveying installation with a chamber pump is affected by gas flows in a chamber pump and in a transport pipeline. Particles of material in a transport pipeline of constant cross section under the influence of a gas flow move progressively along a helix (Evstigneev VN Pipeline transport of plastic and bulk materials in construction. M: Stroyizdat, 1989). Taking into account the rotational motion of material particles along the screw more accurately takes into account the nature of the aerodynamic processes of material movement in the transport pipeline with lower drag coefficients. Allows you to get the most effective mode of operation. The energy savings in this case are much greater.

 However, with the known method, the chamber pump does not intentionally twist the gas flow in a spiral. The movement of the material both translationally and along the screw is not supported along the length of the pipeline and quickly damps.

 A known method of transporting bulk materials, implemented by the device described in SU 1615089 A1, 12/23/1990, which consists in the fact that the supply of compressed gas through the pipe for aerating compressed gas of bulk material, an additional supply of gas flows dispersed along the length of the transport pipeline through the activators, these gas flows are supplied at an angle of rotation of the helix to create a spiral-like movement of material in said pipeline.

 In this method, there is no twisting with compressed gas of the transported material in the chamber feeder and feeding the swirling material-gas mixture into the pipeline. There is also no supply of additional gas flows at an angle of movement of the material, which underestimates the transportation distance, does not reduce the destruction of the grain size of the transported material, reduce energy consumption, and increase the reliability of the pneumatic transport system.

 The purpose of the invention is to reduce energy consumption, increase the transportation range, reduce the destruction of the granular composition of the materials transported and increase the reliability of the pneumatic transport system.

где с - коэффициент пропорциональности, который равен отношению абсолютной скорости перемещения материала к скорости газа, которым перемещают материал;
V - скорость движения газа;
t - время перемещения материала;
ln - натуральный логарифм;
b - коэффициент, учитывающий физико-механические свойства транспортируемого материала, определяемый по формуле
b = 3Kρ_в/(4dρ_m),
где К - коэффициент аэродинамического сопротивления;
d - средний диаметр частиц транспортируемого материала;
ρ_в, ρ_m - плотность газа и транспортируемого материала соответственно.This is achieved by the fact that in the method of transporting bulk materials, including supplying compressed gas through a nozzle to a chamber feeder for aerating the bulk material with this gas, additionally supplying gas flows is distributed along the length of the transport pipeline through the activators by supplying these flows at an angle of rotation and with a helix pitch with the formation of a helical movement of the material, through the said nozzle, compressed gas is supplied to the chamber feeder in a twisted state with the possibility of twisting the material of the mixture and in a twisted state, this mixture is fed into the transport pipeline, in which a screw-like movement of the material is formed, which is formed when moving along the transport pipeline, by supplying the said flows at an angle of rotation and in increments equal to the same parameters of the said spiral-shaped movement of material, determined from the following dependencies:
h = πD / (1 / tg ² φ) ^1/2 ,
where h is the helix pitch;
D is the inner diameter of the pipeline;
φ is the angle of rotation or the angle of elevation of the helix;
the value of the reciprocal of the tangent in the square of the angle of elevation of the helix of the motion of the particle of the material is determined from the ratio

where c is the coefficient of proportionality, which is equal to the ratio of the absolute speed of movement of the material to the speed of the gas by which the material is moved;
V is the gas velocity;
t is the time of movement of the material;
ln is the natural logarithm;
b - coefficient taking into account the physical and mechanical properties of the transported material, determined by the formula
b = 3Kρ _in / (4dρ _m ),
where K is the drag coefficient;
d is the average particle diameter of the transported material;
ρ _in , ρ _m - the density of the gas and the transported material, respectively.

 The claimed method is implemented on a discharge pneumatic conveying installation, shown in figures 1 and 2.

 Pneumotransport installation contains a chamber pump 1 with a duct system 2 and a pipe 3 for supplying the main stream of compressed air. The transport pipeline 4 is equipped with activators 5, to which a bypass duct 6 is connected.

 The method is as follows.

In the chamber pump 1 through the pipe 3 serves compressed air in a swirling state, which in turn aerates the material. The material-air mixture swirls in a spiral fashion. Getting in the form of a spiral into a transport pipeline of constant cross-section, the material acquires a helical motion with an angle of rotation of the helix φ and pitch h. In a rotational motion along a helix, material particles in the gas stream have lower drag coefficients. In this case, the power spent on moving the material through the pipeline at a given capacity and at pressures of 0.05-0.4 MPa is determined by the following relationship
N = 0.5 • M • V ² • (1 + 1 / tg ² φ),
where M is the mass of transported material per second;
V is the gas velocity;
φ is the angle of rotation of the helix or the angle of elevation of the helix.

In this case, the tangent of the angle of elevation of the helix tgφ = h / π • D. From here:
h = tgφ • π • D
or
h = π • D / (1 / tg ² φ) ^1/2 .
The reciprocal of the tangent in the square of the angle of elevation of the trajectory of the material particle is determined by the dependence (Evstifeev V.N. Pipeline transport of plastic and bulk materials in construction. M.: Stroyizdat. 1989, 223)
1 / tg ² φ = {c ² • V ² • t ² / [V • t-ln (b • V • t + 1) / b ² ]} - 1,
where c is the coefficient of proportionality, which is equal to the ratio of the absolute speed of movement of the material to the speed of the gas by which the material is moved;
V is the gas velocity;
t is the time of movement of the material;
ln is the natural logarithm;
b - coefficient taking into account the physical and mechanical properties of the transported material, determined by the formula
b = 3 • K • ρ _B / (4 • d • ρ _m ),
K is the drag coefficient;
d is the average particle diameter of the transported material;
ρ _B , ρ _m is the density of the gas and the transported material.

 To maintain constant φ and h along the length of the transport pipeline, additional compressed air is supplied through activators 5 at the same angle φ and step h.

 The supply of a compressed gas stream is carried out along the length of the transport pipeline at its inlet, after elbows, turns, switches, in vertical sections.

 The proposed method provides a reduction in energy consumption by reducing gas consumption, achieved by the mode of transportation in an organized, progressive and helical manner with an increased concentration of the material-gas mixture and its reduced speed. An increase in the transportation distance is ensured by a dispersed gas supply along the length of the transport pipeline through the activators at an angle φ and pitch h, which repeats the movement of the material along the screw. Reducing the destruction of the granular composition of the transported material, especially at bends, is ensured by the organized movement of particles of material along the screw, which reduces their collision. The reliability of the pneumatic conveying system is increased due to the absence of guide elements inside the chamber feeder and in the pipeline, as well as due to the elimination of obstruction by transported material, which is immediately washed out by supplying additional gas flows dispersed along the length of the pipeline and with a calculated step.

Claims (1)

A method of transporting bulk materials, including supplying compressed gas through a nozzle to a chamber feeder for aerating the bulk material with this gas, additionally supplying gas flows is distributed along the length of the transport pipeline through activators by supplying these flows at an angle of rotation and with a helical pitch to form a helical movement of the material, characterized in that through the said nozzle the compressed gas is supplied to the chamber feeder in a twisted state with the possibility of twisting the material-gas in a mixture and in a twisted state, this mixture is fed into a transport pipeline in which a screw-like movement of material is formed, which is formed when moving along a transport pipeline by supplying said flows at an angle of rotation and in increments equal to the same parameters of said spiral-shaped movement of material, determined from the following relationship
h = πD / (1 / tg ² φ) ^1/2 ,
where h is the helix pitch;
D is the inner diameter of the pipeline;
φ is the angle of rotation or the angle of elevation of the helix;
the value of the reciprocal of the tangent in the square of the angle of elevation of the helix of the motion of the particle of the material is determined from the ratio

where c is the coefficient of proportionality, which is equal to the ratio of the absolute speed of movement of the material to the speed of the gas by which the material is moved;
V is the gas velocity;
t is the time of movement of the material;
ln is the natural logarithm;
b - coefficient taking into account the physical and mechanical properties of the transported material, determined by the formula
b = 3Kρ _in / (4dρ _m ),
where K is the drag coefficient;
d is the average particle diameter of the transported material;
ρ _in , ρ _m - the density of the gas and the transported material, respectively.

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