RU2424U1 - PNEUMATIC INJECTOR - Google Patents

Abstract

1. Pneumatic nozzle for internal mixing with a swirl of gas, comprising a housing, a pipeline for supplying liquid, an insert with a screw guide and a mixing cavity, characterized in that the insert is made in the form of a circular blade grille with channels for gas passage, and the mixing cavity in the form of an annular chamber , the dimensions of which are determined from the relations where h, h, h is the height of the annular chamber for the outer radius R, the intermediate radius R and the inner radius R, while the dimensions and arrangement of the channels of the circular grating for gas passage about are defined by the following relationships: where a is the width of the channel; G is the gas flow rate; S is the gas density; C is the gas velocity at the outlet of the channels, sufficient to crush the droplets to a given size D; n is the number of channels of the circular lattice; h is the height of the annular chamber at the outer radius R; α is the angle of inclination of the channels of the circular lattice to the plane of its output section; h is the height of the annular chamber at the inner radius R; G is the flow rate of drops, where S, S are the density of the drops and gas; C is the aerodynamic drag coefficient of the liquid drops .2. The nozzle according to claim 1, characterized in that the annular chamber on the lateral surfaces has annular protrusions.

Description

-JJW / 7 (P (J3

Pneumatic nozzle

The proposed utility model relates to the field of liquid atomizers used in various branches of technology and can be used for sawing various types of liquids, including viscous and containing a significant amount of dissolved and suspended solids.

Known pneumatic high-pressure nozzle for sawing liquids with high viscosity and the content of dissolved and suspended solids, containing channels for supplying liquid and gaaa, an annular gap formed by a cone and deflector and a window for supplying secondary air (see, for example, Pavel D.G. , Gadustov BC Liquid Sprays - M., Chemistry, 1979, pp. 154-156, riceLULZa).

In this nozzle, the liquid flow is initially organized in the form of a film on the surface of the cone, and then crushing it by jets of gas. The disadvantage of this nozzle is not a good spray of viscous liquids due to a single-stage crushing process. Such nozzles are Day-Slaughter, because after the crushing process, the gas flow of droplets has a large kinetic energy and it is practically difficult to reduce it, for example, using a diffuser. In addition, nozzles are prone to clogging of the supply channels and the formation of soot on surfaces.

Also known is a pneumatic nozzle for internal mixing with swirling gas, comprising a housing and channels for supplying liquid. An insert is mounted along the axis of the nozzle body, equipped with an external screw guide for swirling the gas entering the mixing cavity (see, for example, Pazhi D.G., Gayaustov BC Liquid Sprays -Id., Chemistry, 1979, etr.149-150, fig. .b)

The fluid through the channel and then through the nozzle in the screw insert is fed into the mixing cavity, where it forms a film on the inner surface, which flows out of the nozzle and is crushed by a rotating gas stream.

MKI KZDOLO

liquid due to the impossibility of influencing the droplets formed after crushing the film, the deterioration of cut for the same reason in increasing the viscosity of the liquid. The screw guide for swirling gas is intended only for uniform distribution of the film around the circumference of the nozzle. The high range of the nozzle due to the relatively high gas velocities in the nozzle necessary to ensure the required cut. Exposure to clogging due to the relatively small size of the nozzle in the screw insert for supplying fluid to the mixing cavity.

The purpose of the utility model is to improve the cutting of a high-pressure pneumatic nozzle and increase its performance by reducing the risk of clogging of channels.

This goal is achieved by the fact that in a pneumatic nozzle of internal mixing with a gas swirl containing a housing, a pipeline for supplying liquid, a liner with a screw guide and a mixing subnet, the liner is made in the form of a circular spatula lattice with channels for gas passage, and the mixing cavity in the form of an annular cameras sizes

which are determined from the relations

/; A-II

 at

where / c-G is the height of the annular chamber for the outer radius RJ

intermediate radius og and internal radius Kgt with the dimensions and arrangement of the channels of the circular grating for passage

gas are determined by the following relation

Јг

/ /: уf ,,,, fe + бг) Г & Г -,. &. . ,

l - & Ј (. С b - у i х, ЛЬА fyfMhi

Јi

fca

 . -J / & M

Cg is the gas velocity at the outlet of the channels, sufficient to crush the droplets to a given size Dk; p is the number of channels of a circular lattice; fii is the height of the annular chamber on the outer radius RJ; - the angle of inclination of the channels of the circular lattice to the plane of its output section;

/ L is the height of the annular chamber with an internal radius Eg; fe is the drop rate;

, 4&

A -, U g-

J S h, C and

where LD is the density of drops and gas;

C is the aerodynamic drag coefficient of liquid droplets.

In this case, the annular chamber on the lateral surfaces has annular protrusions.

The proposed solution will allow you to get the necessary cut drops with a greater guarantee than in the known pneumatic nozzles. This is due to the organization of centrifugal forces due to the rotation of the gas flow in the annular chamber. Drops having a size larger than a given diameter Dk will be discarded by centrifugal forces to a circular lattice, where the process of liquid crushing is repeated. With the accepted dimensions of the chamber and the channels of the grating, only droplets of a smaller size than DK can escape from the nozzle.In addition, the level of gas velocities and drops at the outlet of the nozzle decreases, as a result of which such an undesirable factor of their operation as the range of the nozzle flame decreases. Thus, the nozzle cutting is improved and its performance is improved by reducing the risk of clogging of the channels.

The essence of the utility model is illustrated by the drawing, where Fig. X schematically shows a pneumatic nozzle; figure 2 is a section aa at the company.

vyu camera 5, the outlet 6, openings 7 for the passage of fluid into the annular chamber 5. The annular chamber 5 on the side surfaces has annular protrusions 8,

The nozzle works as follows.

The stream of compressed gas enters the nozzle body I and flows through the channels 4 of the circular grill 3 into the annular chamber 5. The gas outflow rates from the channels 4 are quite high (approximately equal to the speed of sound).

The fluid through the pipeline Z and through the holes 7 located directly behind the circular grill 3 enters the annular chamber 5. The fluid flow rate is relatively low 2-10 m / s. In the annular chamber 5, the initial crushing of the incoming liquid occurs, which is discarded by the centrifugal forces of the gas flow to the output edges of the circular grating 3. 3. The film formed at the same time on the blades of the lattice drains from them and is crushed by the gas flow to the specified sizes Dk. In the annular chamber 5, these droplets accelerate and, further, rotate in a spiral to the outlet 6.

After the drop has reached the outlet section of the annular chamber 5, it enters the stream with the axial velocity of the gas and is carried out through the outlet 6 of the nozzle. The dimensions of the outlet 6 or, accordingly, the radius of the outlet section of the annular chamber 5 are determined by the above expression. If the droplet had a size larger than Dk, then it again moves from the center to the periphery of the rotating flow, separates onto the blades of the circular lattice 3 and again repeats the process described above.

41 -I-

To prevent an excessively large flow rate of liquid on the side surfaces of the annular chamber 5, there are protrusions 8. Drops of liquid separated after the circular grill 3 on the side surfaces of the annular chamber 5 in the absence of a protrusion would flow into the outlet 6 and then would be crushed in the usual way, as described above disadvantages In the presence of a protrusion, the film flowing from it to the inside is crushed by a rotating stream of gas. The resulting droplets have a size larger than Jk, since the gas velocity in this place is less than at the exit from the grate. These cereals are discarded by centrifugal forces back to the grate, again crushed and carried out through the outlet with the rest of the droplets. The dimensions of the protrusion are small enough to not substantially distort the gas velocity field in the annular chamber.

For the normal functioning of the nozzle, the correct choice of the gas velocity at the outlet of the channels 4 of the circular grating 3 is necessary. It is rational to choose the value of Cr so that the dimensions of the droplets formed after crushing them by the gas flow are equal to the specified diameter Dc The droplet sizes after crushing by the gas flow can be determined for example, according to Weber’s relevant criteria, go to the recommendations of the above monograph.

The annular chamber 5 forms the desired velocity range, which does not release particles above a predetermined size. In this case, centrifugal forces will only release droplets from the chamber that are smaller than Dc. The moment of momentum is stored in the chamber (not taking into account the friction of the flow against the walls), and therefore, by the time the gas escapes to the outlet 6, centrifugal forces increase, i.e. peripheral gas velocities increase, rotation radius decreases. As a result, a trap is formed for droplets larger than Dc. If the chamber were not white, large droplets after crushing would be carried away by the gas flow. The reason for this is the presence of the axial velocity of the gas and a decrease in the centrifugal force as the droplet moves to the center (due to the rotation, the law firmly Y / 7

th body1). Without a chamber, primarily due to the axial velocity of the gas and the circulation of the gas flow (reverse current), the moment of momentum toward the center drops sharply. In the chamber, it decreases due to friction of the gas flow against the walls and its redistribution between gas and liquid. As a first approximation, we neglect friction against the walls. Thus, a peculiar trap is formed - on the one hand a circular lattice, on the other - centrifugal forces in the chamber.

The above ratios are calculated using a system of six equations describing the motion of droplets in a gas stream,

and presented in the book Physical Fundamentals of the Workflow in the Chamera of Combustion of Aircraft Engines Raushenbakh B.V., Bely S. A., Bespalov I., V. et al., Mechanical Engineering, 1964, p. 526. For calculations on it, a program for ES was specially developed. The calculations confirmed the fundamental possibility of obtaining the above-described pattern of droplet motion in the annular chamber of the nozzle. After stabilization of the rotating drop at some current radius, the Bottom of the equation of motion of the drop

in the radial direction:

Z.S.SS. Y / g & / Y Gg) g

DЈ. 71 (Cu (, - Sk) + (Sg, Sy),

cLV where, are the droplet velocities in the radial and circumferential directions,

Cg, same as gas, is time, gas and droplet density, C w is aerodynamic drag coefficient of droplets, Dk is droplet diameter, the following relation can be obtained:

 o / ClU,) p. / 1

(

When deriving it, it was taken into account that the peripheral velocities of drops and gas

are almost identical, and the velocities and accelerations of the droplets in the radial direction are close to zero.

No. / Wjfo # 0 is tal with a height above the floor where is the floor .. where, This equality allows us to determine the value of the known axial values. In addition, in the calculations, the inevitability equation for gas in the section 2 & b (/ b3, Jj. B & b Ј% we have G. . (zag P pet-P-FFT l ") A, th. Here G-g is the gas flow rate, and Cg are the gas velocities in radial circumferential directions in the output section of the annular chamber, and that of the circular circular chamber in the output section. Using equalities moment of momentum in sections I and 2 6g Сг-ц.1 & (& r + (Гк) Sy2 & Ј tea, / 1 (tk.) Г -Г & Z (.1 & J Lszu, 4 (3) indices I and 2 carry I to the parameters in sections I and 2 When deriving equation (3), the following was neglected: the friction of gas against the walls, the difference between the droplet and gas in section 2, the droplet velocity in section I, heat and mass transfer of gas with drops, substituting relations (2) and (3) in equality with tea,.; (), 2Ush & Ј $ Using the equation of gas flow through the channels of a circular lattice 6g - $ b & b (5) С - gas velocity not leaving the channels, n - number of channels, - // - & 4 0 Sft 0 # / / C-iid-j

In the preparation of equation (5), it was taken into account that the velocity rasa Cgwn was selected from the condition of sufficiency for crushing the liquid to a given size Dc. In addition, the height of the channels Јl was taken to be equal to the height at the gas inlet to the annular chamber. From equality (5)

 f -P (c)

Jv

We perform an analysis of the influence of the height of the chamber - for an intermediate value of It on the half-awful re-result. Consider barking the chambers where the velocities of the droplets and gas were aligned Repeating the Swede of equation (1) with respect to the parameters in the output section 2, we have:

Ј2 ± Ј. . - PG (7)

& ъ у fl Here Сггг, Сгг - circumferential and radial velocities of the eider at the current

radius B, When deriving this ratio, it was assumed that the value of A and the size of the retained droplets Dk for the considered values of R and R2 are the same

From the condition of conservation of angular momentum of the mixture we have:

7- l-V

(i-Us- K-z,

According to the equation of flow through the annular cross sections for It and 12

t,.,,

we get

(B & b &, & -, (9)

From the above equalities we have

(10)

V

The last ratio shows what the height of the annular chamber should be in order to hold a drop of a given size Dk. If this height is greater, then droplets of this size will be thrown back by centrifugal forces back to the circular lattice, if less, then drops larger than the specified size Dk will move to the exit from the annular chamber. Both of these deviations in the height of the chamber are undesirable, since they

-1 $ - & 0ffe & ff

either to waste gas energy for re-crushing and acceleration

drops, or to enlarge the spray. In this regard, when designing a nozzle, its height should be chosen taking into account equality (10).

The procedure for performing calculations according to the above equations is as follows.

Initially, the values of the gaea okoros are selected in the weekend 2, they depend mainly on the required angle of the torch opening. According to them, taking into account the flow rate, the radius of the outlet E2 and the height of the annular chamber at this location / v2 are determined. Then, the outer radius of the annular chamber And is selected and, by the ratio (10), the value p / 1. Using the equality (6) m of the selected gas velocity in the channel C g, the number of channels and other known quantities determines the width of its passage section a. With this, the height of the channels is taken equal to AI so that the physical processes described above in the annular chamber occur uniformly in its height At the end of the calculation with Eq. (4), there is the angle}, the inclination of the channels to the plane of the output section of the circular lattice. The heights of the annular chamber n for intermediate values of the radii are determined by equality (10).

As an example, we consider the operation of a nozzle with the injection of effluents into the furnace of a boiler of the BKZ-160-YuO type at Lenznergo central heating plant-7.

Sewage in the amount of 0.4 t / h is supplied through the liquid supply pipeline Z e at a low speed (up to 4 m / s). At the same time, steam is supplied to the body of the nozzle I under a pressure of 0.4 MPa. The entire steam pressure drop is triggered in the channels of the circular grid 3 at the output of non-channels, its speed is approximately 500 m / s The amount of steam supplied is 0.1 t / h

This speed var at the outlet of the channels of the lattice 3 provides the crushing of drops to a given size Dc 20 microns.

Assuming an average steam exit speed of 60 m / s from the nozzle outlet, a radial steam speed of 60 m / s, we determine a radius of Ј2 0.015 m and A-2 0.01 m. We choose a value of 22 0,0 0.03 m, then willow (10)

  0.014 u. Given the size of the droplets in the outlet Дк -20 / v / w, we determine the steam velocity m / s required for liquid spraying. The size of the channels with the adopted number of / 4 and the height of the annular chamber at the inlet-IL 0.0X4 m is 2.0. At the end of the calculation using equation (4) is from 82.8 degrees.

22 w

Director

P.V. Ilyin

Claims (2)

1. Pneumatic nozzle for internal mixing with a swirl of gas, comprising a housing, a pipeline for supplying liquid, an insert with a screw guide and a mixing cavity, characterized in that the insert is made in the form of a circular blade grill with channels for gas passage, and the mixing cavity in the form of an annular chamber whose dimensions are determined from the relations

where h ₁ , h, h ₂ - the height of the annular chamber for the outer radius R ₁ , the intermediate radius R and the inner radius R ₂ , the dimensions and arrangement of the channels of the circular grating for the passage of gas are determined by the following relationships:

where a is the channel width;
G _g - gas consumption;
S _g - gas density;
C _g - gas velocity at the outlet of the channels, sufficient for crushing drops to a given size D _to ;
n is the number of channels of the circular grid;
h ₁ - the height of the annular chamber on the outer radius R ₁ ;
α is the angle of inclination of the channels of the circular lattice to the plane of its output section;
h ₂ - the height of the annular chamber with an internal radius R ₂ ;
G _to - the consumption of drops,

where S _to , S _g - the density of drops and gas;
C _w - aerodynamic drag coefficient of liquid droplets.  2. The nozzle according to claim 1, characterized in that the annular chamber on the lateral surfaces has annular protrusions.