FR2493732A1 - Disperse aerosols esp. for medicine or industry - produced by entraining gas stream encountering symmetrical oblique opposing streams at higher velocity - Google Patents

Abstract

Liq. and solid dispersed aerosols are aerodynamically produced by contacting the particles with a gas jet which conveys them towards an obstruction. The gas jet encounters a symmetrical resistance from other gas jets having a discharge velocity exceeding that of the gas jet entraining the particles by a factor of 1.2-20 and oriented to converge at an angle of 30-90 deg.C. Used as inhalation and/or disinfection prods. in medicine and veterinary work or for prodn. of fine and superfine substances in the foodstuffs industry, for dyestuffs etc. The method enables aerosols with finely dispersed particles of size less than 1 micron to be generated with min energy consumption.

Description

The present invention relates to a process for pre-

  aerodynamic paration of liquid and solid aerosols available

  perses. The above-mentioned dispersed aerosols find wide applications in various branches of the national economy.

  nale. This is how liquid aerosols are used.

  persés in medicine for the treatment of various conditions by inhalation. Aerosols of this type are used in

  veterinary art for disinfection of operating premises

  tation. The activity of liquid aerosols depends on their de-

  dispersion and their stability, which is a function

  of the method of preparation of dispersed liquid aerosols.

  In a certain number of branches of chemical industry, food, in the industry of the materials of

  constructions, etc., it is essential to implement

  see finely and very finely ground materials, such as mineral salts, fillers, dyes, pigments,

  ion exchange resins. We isolate these fine materials

  and very finely dispersed from dispersed solid aerosols. The degree of dispersion of solid particles

  also depends on the process for the preparation of aerosols

scattered.

  There are various processes for the preparation of air-

  dispersed liquid and solid rosols.

  We know in particular a preparation process

  liquid aerosols dispersed by means of ultrasound (see O.K.

  Eknadiosiants "The physical foundations of technology

  ultrasound "(in Russian), Moscow, Ed." Nauka ", 1970).

  In carrying out this method, a jet (a film) of liquid is admitted onto the oscillating element of a magnetostriction generator, in other words, ultrasonic frequency oscillations are applied to the liquid. The effect

  ultrasound causes the iso-

  from the crests of microwaves.

  This process allows for a range of disper-

  narrow aerosol size, the particles of which fall within the limits of 1 to 4.8 microns. However, this process

  does not find broad applications because it does not allow ato-

  use only liquids with low viscosity. In addition, for the realization of this process, it is necessary to use special ultrasonic generators which are very expensive (the cost of atomizing a liquid by ultrasound

  3 to 5 times that of atomization by processes

  pneumatic or mechanical). In the aerodynamic process for the preparation of dispersed liquid aerosols, the dispersion of the liquid is

  a consequence of the dynamic contacting of the listening

  lement of a liquid with a gas flow (cf. L.A. Vit-

  man I The atomization of liquids in injectors "(in Russian), Moscow, 1.962, D.G. Pazhi, V.S. Galustov" les

  liquid atomizers "ô (in Russian) s, oscou, 1979 On 0 ap-

  folds the process so that the gas stream leaves the nozzle at a high flow rate of 150 to 300

  m / s, while the liquid flow speed remains low

  derée. The greater the difference in gas flow velocities

  and the higher the liquid, the higher the degree of dispersion of the 1i-

  which is considerable. In the end, we get aero-

  liquid soils dispersed over a very wide dispersion range (from 1.0 to 100 microns). This process requires a very high energy consumption, does not disperse very viscous liquids. In addition, this process requires the

  use of special liquid pumps for re-

liquid leakage.

  Yet another method of preparing dispersed liquid aerosols is known by atomizing a liquid

  by means of a gas jet in the presence of ferro-

  magnetic solids (USSR author's certificate No. 387 570). According to this process, ferromagnetic particles are introduced into a liquid, then the

  mixing across the operating area of an electric field

  alternative magnetic. Ferromagnetic particles

  moving in the direction of the lines of force electroma-

  genetics separate the continuous flow of liquid into ele

  detached parts which are then transported by the jet of

  gas atomizer, are dispersed again and are entrained.

  During the dispersion of a liquid by this pro-

  yielded, there is inevitably a partial training of the par-

  ferromagnetic sheets with atomized liquid. This li-

  seriously considers the possibilities of using the process

  dice (the presence of mixed solid particles is inappropriate

  missible when preparing dispersed liquid aerosols used in particular in medicine, in the veterinary art). The moderate average degree of dispersion of the particles of a liquid to be dispersed (to be atomized) as well as the need

  to implement complicated systems for the organization

  electromagnetic fields limit the applications

process.

  Among the known processes for the preparation of air

  solid dispersed soils, the most advanced is the aero-

  dynamic. It is based on bringing a jet of

  gases with solid particles, which are sucked up in the em-

  blockage of the jet then which are conveyed by the gas jet until their impact against an obstacle, it being understood moreover that during the movement of the particles there is a mutual attrition of the particles between them as well as an attrition with the walls of the device (VI Akunoc I Jet mills "(in Russian), Moscow, 1967; PM Sidenko, n Crushing in the chemical industry" (in Russian), Moscow 1977). This process is carried out in jet mills

  flat, vertical or counter-milling chamber.

  In the preparation of solid aerosols dispersed by the jet process, the following phenomenon occurs: 1) A weak impulse of impact of the particles

  during their percussion against the obstacle. This is explained

  also because the acceleration of the particles takes place in a divergent gas flow. So there follows a

  particle velocity drops, and particles ac-

  which have a low kinetic speed. Therefore, the rea-

  The process depends on the hardness of the materials to be

start grinding.

  2) A high degree of wear on tire accelerators

  materials used in counter-current jet grinding

  since the dispersed solid aerosol moves relatively

  the walls of the high-speed apparatus and

  titues a highly effective abrasive.

  3) By carrying out the said process, aerosols are obtained in a wide range of dispersion, in most cases from 2 to 10 microns and sometimes the limit of

  upper dispersion reaches 30 microns while the limit

  te lower goes down to 1 micron. This is explained by the low kinetic energy at the time of the collision of the

  solid particles with an obstacle and by the low proba-

  bility of collision of said particles with each other.

  We therefore proposed to create an aerody-

  namique of preparation of liquid and solid aerosols available

  which allows them to be obtained in a range of

  narrow persion with particle sizes less than 1 micron, with minimal energy consumption and

  which allows, on the other hand, to adjust the degree of dispersion.

  The solution to this problem is that

  in the aerodynamic process according to the invention of preparations

  tion of dispersed liquid and solid aerosols by bringing the liquid or solid particles to be dispersed into contact with

  a gas jet and with subsequent transport of said particles

  them by a gas current until their impact with an obsta-

  key, according to the invention, subjecting said jet of trans-

  bringing the liquid or solid particles to a symmetrical constriction by gas jets whose flow speed exceeds by 1.2 to 20 times the flow speed of the gas jet transporting the liquid or solid particles, the

  gas jets being symmetrically oriented so as to obtain

  nir, from an angle of 30 to 90, their homocentric convergence

than on the obstacle.

  As indicated above, the claimed process consists in subjecting the gas jet

  main carrying the liquid to be dispersed or the solid phase

  to grind to a symmetrical constriction by gas jets in order to obtain a homocentric convergence of their axial components in a single point where a solid obstacle is placed, faired, for example, a sphere, a cylinder, a solid steel disc. In this case, there is

  a transformation of the kinetic energy of the main gas jet

  cipal containing liquid or solid particles with ac-

  impactful subsequent action on solid particles or

  liquids to be dispersed from the solid obstacle.

  The gas jet flows at a speed of 10 to 100

  m / s and atomizes the liquid or accelerates the solid particles

  as soon as admitted into the gas flow area. Then, during the transport of solid or liquid particles by the gas jet (vector flow), said jet is subjected to a symmetrical constriction by gas jets whose flow speed is from 100 to 320 m / s. The axial components of said jets converge into a

  single point (the angle of convergence of the symmetrical gas jets

  triques is 30 to 900C). In this case, there is a phenomenon

  nomene analogous to the passage of a gas flow through

  a venturi formed by symmetrical gas jets. Quickly

  se flow of these gas jets exceeds the speed of

  the main vector flow from 1.2 to 20 times. The reduction-

  tion of the cross-section of the vector flow and, consequently

  quent, its acceleration, occurs without significant losses

  of energy by friction. As the reduction

  tion of the vector flow section there is an ac-

  rapid growth of its kinetic energy which contributes

  an increase in the transport speed of the particles

  liquids or solids. Then, we transform the kinetic energy of the atomized liquid or accelerated solid particles into impact-energy thanks to the fact that at the point

  of convergence of the axial components of the gas jets

  metrics we place a solid obstacle. In this way we

  subjects particles of liquid or solid phase to ac-

  tion of the impact and we break them definitively with

  tion of a dispersed liquid or solid aerosol.

  By modifying the speed of the symmetrical gas jets

  ques, it is possible to adjust the degree of grinding- (in the direction of decreasing or increasing the dimensions

particles).

  The process according to the invention for aerosol preparation

  dynamics of dispersed liquid and solid aerosols, by comparison with known methods, makes it possible to achieve

  a dispersion of a solid or liquid aerosol in the gam-

required me.

  By the method according to the invention, it is possible to carry out a dispersion of the liquid and a grinding of a solid material with particle sizes less than 1 micron, it being understood that the range of dispersion is narrow. In addition, in the implementation of the method of the invention, the energy consumption is significantly lower than in the known methods (in a report

from 1 / 1.5 to 1/2).

  The process is simple from the point of view of industry.

  ! o trialisation and it is put into practice as follows:

  boasts. A gas is admitted through a nozzle in which the main gas jet is formed. The material to be dispersed (a liquid or solid particles) is admitted into the gas outlet zone, outside the nozzle. At the mouth of the jet comes the prior dispersion of the liquid or solid particles which are entrained by the gas jet

  and are transported to the obstacle. We tighten symmetri-

  only the jet of carrier gas of liquid or solid particles by other gas jets. Jet streams

  tightening gases are produced from nozzles

  laid in such a way, with respect to the nozzle from which the main gas jet is formed, that one obtains at an angle of 30 to 90 a homocentric convergence of the gas jets on the obstacle. Accelerated particles

  liquid or solid material strike the obstacle

  key and we get their final dispersion until

  desired degree of dispersion. We adjust the degree of dispersal

  by modifying the ratio of the speed of the gas jets which operate the symmetrical constriction

  as well as the speed of the main gas jet.

  Other characteristics and advantages of the

  vention will be better understood on reading the description

  tion, which will follow, of several exemplary embodiments.

Example 1:

  We send in a pneumatic injector (diameter

  from the outlet nozzle 3 mm) from air to temperature

  re of 200C. The air flow speed at the outlet of the nozzle is 90 m / s. At the same time, water is admitted into the injector nozzle. Mass flow of water

is 5 kg / h.

  The jet of carrier gas of the liquid is tightened by four symmetrical air jets whose flow speed is 110 m / s. The nozzles from which the necking gas jets depart are arranged so as to converge so

  homocentric. The angle of convergence of the axia-

  the said necking jets being 30. At point

  convergence of the jets is installed a steel sphere

pe 18 mm in diameter.

  The liquid aerosol obtained is composed of particles

dispersed from 5 to 20 microns.

  By way of comparison, an analogous aerosol (water, air) is obtained in the following manner. We admit into the nozzle of an injector with a diameter of 3 mm of air, the speed of flow of air at the outlet of the nozzle is

  90 m / s, the air temperature is 200C. Simultaneous-

  We admit into the nozzle of the water injector, the

  mass flow rate of water intake is 5 kg / h. Aero-

  soil is composed of particles dispersed from 30 to 100 mi-

crons.

Example 2

  We send in a pneumatic injector (diameter-

  be from the outlet nozzle 2 mm) of air at a temperature of 200C. The air flow speed from the nozzle is 15 m / s. Simultaneously, a 10% glycerin solution is admitted into the injector nozzle. The flow

  mass intake of glycerin is 2 kg / h. We are-

  clamps the jet of carrier gas of the liquid by six symmetrical jets

  air ques whose flow speed is 300 m / s. The

  nozzles from where the necking gas jets are available

  so that they converge in a homocentric way

  that, the angle of convergence of the axial components of the necking jets being 580. At the point of convergence of said jets is installed a steel sphere 10 mm in diameter. The aerosol obtained is composed of particles

dispersed from 0.5 to 1 micron.

Example 3:

  We send in a pneumatic injector (diameter-

  from the outlet nozzle of 0.5 mm) from nitrogen to temperature

  erasure of 150C. The nitrogen flow speed at the outlet of the nozzle is 50 m / s. Simultaneously, the acid corresponding to the formula CH3 (CH2) 2COOH is admitted into the nozzle of the injector. Mass flow rate of acid intake

  is 0.8 kg / h. The jet of liquid carrier gas is tightened

  quide by three symmetrical nitrogen jets whose flow speed is 300 m / s. The nozzles from which the

  necking gas jets are arranged so that the-

  said jets converge homocentrically, the angle

  of convergence of the axial components of the stricture jets

  tion being 40. At the point of convergence of said jets

  a 6 mm diameter steel sphere is installed. The ae

  liquid rosol obtained is composed of dispersed particles

from 3 to 8 microns.

Example 4

  One sends in a nozzle of 4 mm of air diameter at the temperature of 200C, the speed of flow of the air at the exit of said nozzle being of 100 m / s. We admit in the air outlet area, outside the nozzle,

  titanium dioxide having average dimensions of

  isolated and agglomerated sheets up to 100 microns. The carrier gas jet of solid particles is tightened by four symmetrical air jets which escape from the nozzles at a flow speed of 320 m / s. The nozzles of o

  escape the four air jets are arranged in a way

  re that said air jets converge homocentrically

  that the angle of convergence of the axial components of the

  said jets being 30. At the point of convergence of the jets

  a titanium sphere 20 mm in diameter is mounted. The ae

  rosol obtained is composed of dispersed particles of 0.5

to 1 micron in dimensions.

  Example 5: One sends in a nozzle of 5 mm of air diameter at the temperature of 250C. The air flow speed out of the nozzle is 150 m / s. We send in the

  air outlet area, outside the nozzle, an exchanging resin

  ion gayer having an average particle size of 1000 microns, at a mass flow rate of 5 kg / h. The jet of carrier gas of solid particles is tightened by eight symmetrical air jets which flow at a speed of 300 m / s. The nozzles from which the eight air jets leave are arranged so that they converge at the same point, the angle of convergence of the axial components of said jets being 900. At the point of convergence of the jets is installed a

  steel sphere 30 mm in diameter.

  The aerosol obtained consists of dispersed particles

sees from 1 to 5 microns.

  By way of comparison, we submitted to the disp-

  sion (during grinding) an ion exchange resin having an average particle size of 1000 microns in a

  jet grinding unit with grinding chamber (or grinding -

  ge) plane. The compressed air flow at the temperature of 200C being 300 m3 / h, the air being admitted under a pressure of

  7 bars. The solid aerosol was dispensed

  dried continuously at a rate of 10 kg / h.

  The ground material was composed of particles

dispersed from 5 to 20 microns.

Claims (1)

CLAIM   Aerodynamic aerosol preparation process   dispersed liquids and solids by contacting the   liquid or solid particles to be dispersed with a gas jet and subsequent transport of said particles by the gas jet until their impact with an obstacle, c - characterized in that said gas jet carrying the liquid or solid particles is subjected to a sietric tightening by gas jets, the flow speed of which is 1.2 to 20 times greater than the deceleration speed of the gas jet transporting liquid or solid particles, the gas jets being oriented symmetrically so that their homocentric convergence takes place at an angle of 30 to 90 on the obstacle.