RU2541019C1 - Venturi scrubber - Google Patents

Abstract

FIELD: machine building.

SUBSTANCE: Venturi scrubber contains a confusor, manhole, diffuser, sprinkling system, knockout drum, in the confusor the spraying device is installed containing water pipeline made in form of two mutually perpendicular sections, one section is located axisymmetrically to the confusor, and at its end at manhole side the spraying system nozzle is installed, at that input hole with diameter d1 of the confusor and output hole with diameter d3 of the diffuser are connected respectively with supply and outflow pipelines, and diffuser output connected with the outflow pipeline is tangentially connected with the bottom part of the cylindrical casing of the straight-flow cyclone acting as knockout drum, at that axes of the diffuser and cyclone casing are mutually perpendicular, at that the bottom part of the cyclone casing is connected with the cone bunker for sludge drainage, and top part is connected with the cone chamber to remove the cleaned gas; spraying system nozzle contains casing with union rigidly connected with the casing coaxially located in the top part of the casing and having cylindrical hole for liquid supply connected with the diffuser axisymmetric to the casing and union, and sprayer is connected to the casing in its bottom part by means of three spokes; the sprayer is at right angle to the casing axis and is made in form of the perforated disk.

EFFECT: improved efficiency of gas purification from dust and chemical impurities.

5 cl, 3 dwg

Description

The invention relates to techniques for cleaning gases from dust and chemical hazards and can find application, for example, in iron and steel enterprises.

Closest to the claimed object in terms of technical nature and the achieved result is a device for cleaning gases such as a Venturi pipe according to the author's certificate of the USSR No. 942287, cl. B01D 47/10, 1979, containing a confuser, a neck, a diffuser, an irrigation system and a droplet eliminator (prototype).

A disadvantage of the known device is that with large quantities of purified gases, energy consumption for the control system increases due to the lack of devices for fine atomization of the liquid.

The technical result is an increase in the efficiency of cleaning gases from dust and chemical hazards.

This is achieved by the fact that in the Venturi scrubber, which includes a confuser, a neck, a diffuser, an irrigation system, a droplet eliminator, an irrigation device is placed in the confuser, consisting of a water supply pipe made in the form of two mutually perpendicular sections, one of which is placed axisymmetrically to the confuser, and at its end facing towards the neck, fastened irrigation nozzle, wherein the inlet diameter d converger ₁ and the outlet diameter of the diffuser ₃ d are respectively connected to a supply discharge pipes, and the diffuser output connected to the discharge pipe is tangentially connected to the lower part of the cylindrical body of the direct-flow cyclone acting as a droplet eliminator, while the axes of the diffuser and the cyclone body are mutually perpendicular, and the lower part of the cyclone body is connected to a conical hopper for discharging sludge, and the upper part is connected to a conical chamber for removal of purified gas, and the nozzle of the irrigation system contains a housing with a fitting rigidly connected to the housing, coaxially located in the upper part of the casing and having a cylindrical hole for supplying fluid connected to the diffuser, axisymmetric to the casing and the fitting, and to the casing, in its lower part, by means of at least three spokes, a sprayer is installed that is perpendicular to the axis of the casing and made in the form of a perforated disk .

Figure 1 shows a diagram of a venturi scrubber, figure 2 is a diagram of a venturi pipe, figure 3 is a diagram of a nozzle with a perforated spray disk for an irrigation system.

The Venturi scrubber (Fig. 1) includes a Venturi pipe (Fig. 2), consisting of a confuser 1, a neck 2, a diffuser 3. An irrigation device 4 is placed in the confuser 1, consisting of a water supply pipe consisting of two mutually perpendicular sections , one of which - section 6 - is placed axisymmetrically to the confuser 1, and at its end, facing the neck 2 of the venturi, the nozzle is fixed 7. The inlet with a diameter of d _{1 of the} confuser 1 and the outlet with a diameter of d _{3 of the} diffuser 3 are connected respectively to the inlet 8 and take away 9 pipelines. The diameters of the inlet and outlet openings of the confuser and diffuser d ₁ and d ₃ are taken equal to the diameters of the inlet and outlet pipelines.

The outlet of the diffuser 3, connected to the discharge pipe 9, is tangentially connected to the lower part of the cylindrical body 5 of the once-through cyclone, which serves as a droplet eliminator, while the axes of the diffuser 3 and the cyclone body 5 are mutually perpendicular. The lower part of the cyclone body 5 is connected to a conical hopper 10 for discharging sludge, and the upper part is connected to a conical chamber 11 for discharging purified gas.

Aerodynamically optimal are the following aspect ratios of Venturi tubes of circular cross section:

neck length l ₂ = 0.15d ₂ , where d ₂ is the neck diameter; narrowing angle of the confuser α ₁ = 15 ÷ 28 °,

confuser length $$l_{\mathrm{one}}=\left(\frac{d_{\mathrm{one}}-{\mathrm{<figure-callout\; id="2"\; label="d"\; filenames="00000005.png"\; state="\{\{state\}\}">d</figure-callout>}}_2}{2tg\frac{{\alpha }_{\mathrm{one}}}{2}}\right)$$

The diffuser expansion angle α ₂ = 6 ÷ 8 °,

diffuser length $$l_{}$$$${}_3=\left(\frac{d_3-{\mathrm{<figure-callout\; id="2"\; label="d"\; filenames="00000005.png"\; state="\{\{state\}\}">d</figure-callout>}}_2}{2\mathrm{<figure-callout\; id="2"\; label="t\; g\; \alpha "\; filenames="00000005.png"\; state="\{\{state\}\}">t\; </figure-callout>}g\frac{{\alpha }_{}}{}\frac{{}_2}{2}}\right)$$

At low gas velocities and fine dust, Venturi pipes with an elongated neck l ₂ = (3 ÷ 5) d ₂ should be used, which in this case give increased efficiency. For gas flow rates of up to 3 m ³ / s, round-section Venturi pipes should be used. With large gas flow rates and an increase in the diameter of the pipe, the possibility of a uniform distribution of irrigation over the cross section of a round pipe is sharply worsened. Therefore, several parallel working pipes should be used, and with gas flow rates of more than 10 m ³ / s it is recommended to give the pipe cross section a rectangular (slotted) shape, in which the conditions for organizing uniform irrigation are greatly facilitated.

The nozzle with a perforated spray disk for the irrigation system (Fig. 3) consists of a housing 12 with a fitting 13 rigidly connected to the housing coaxially located in the upper part of the housing and having a cylindrical hole 14 for supplying fluid connected to the diffuser 15, an axisymmetric housing and a fitting . To the housing 12, in its lower part, by means of at least three spokes 17 a sprayer 16 is connected, located perpendicular to the axis of the housing and made in the form of a perforated disk with holes 19. The spray disk 16 is formed by two surfaces, one of which is facing the diffuser 15 , a curved surface, and the line forming this surface is an nth-order curved line, for example, elliptic, parabolic, etc., and the second is a plane.

The spokes 17, by means of which the atomizer disk is attached to the body, are located radially with respect to the axis of the body, and can be made straight or curved in shape, moreover, they are attached to the body using screws 18, and to the disk, or using a detachable connections, for example threaded, or one-piece, for example by contact welding.

The perforation holes 19 in the disk 16 have axes intersecting at a point lying on the end surface of the housing and being the center of the largest circumference of the diffuser 15, while the nozzle atomizer can be made of solid materials, such as tungsten carbide.

Scrubber Venturi works as follows.

The work of Venturi scrubbers is based on the crushing of water by a turbulent gas flow, the capture of dust particles by drops of water, their subsequent coagulation and sedimentation in an inertial type 5 droplet trap. When liquid is introduced into the gas stream, large droplets are crushed into smaller ones due to the energy of the turbulent flow, when external forces acting on the droplet overcome the surface tension forces.

The venturi pipe consists of a confuser 1, which serves to increase the gas velocity, a neck 2, where dust particles are deposited on water droplets, and a diffuser 3, in which coagulation processes occur, and also, due to a decrease in speed, a part of the pressure expended to create a high speed is restored gas in the neck 2. In the droplet eliminator 5, due to the tangential introduction of gas, a rotation of the gas flow is created, as a result of which moistened and coarsened dust particles are thrown onto the walls and are continuously removed from the droplet eliminator 5 in ide sludge.

The Venturi scrubber operates with a high efficiency of 96 ÷ 98% on dusts with an average particle size of 1 ÷ 2 μm and captures highly dispersed dust particles (up to submicron sizes) in a wide range of initial dust concentration in the gas from 0.05 to 100 g / m ³ . When operating in the fine cleaning mode on fine dusts, the gas velocity in the neck 2 must be maintained within 100 ÷ 150 m / s, and the specific water flow rate in the range 0.5 ÷ 1.2 dm ³ / m ³ . This necessitates a large pressure drop (Δp 10 ÷ 20 kPa) and, therefore, a significant energy expenditure for gas purification. In some cases, when the Venturi pipe works only as a coagulator before subsequent fine cleaning (for example, in electrostatic precipitators) or on coarse dust with a particle size of more than 5–10 μm, velocities in the neck 2 can be reduced to 50–100 m / s, which is significantly reduces energy consumption.

The nozzle with a perforated spray disk operates as follows.

The liquid is supplied through a cylindrical hole 14 to the diffuser 15, and from it enters the nozzle 16 under pressure, with this, additional droplets of liquid are crushed due to turbulence of the outlet stream, and the finely dispersed stream leaves the nozzle with a wide spray nozzle (solution).

When irrigation fluid is supplied to the venturi, its initial velocity is negligible. Due to the forces of the dynamic pressure of the gas stream, the drops simultaneously with crushing receive significant accelerations and at the end of the neck 2 acquire a speed close to the speed of the gas stream. In the diffuser 3, the gas flow and droplet velocities fall, and due to inertia forces the droplet velocity exceeds the gas flow velocity, therefore, the capture of dust particles by droplets occurs most intensively at the end of confuser 1 and in the neck 2, where the gas velocity relative to the droplet is especially significant and kinematic coagulation proceeds most effectively.

Claims (5)

1. A venturi scrubber comprising a confuser, a neck, a diffuser, an irrigation system, a drip trap, and an irrigation device is placed in the confuser, consisting of a water supply pipe made in the form of two mutually perpendicular sections, one of which is placed axisymmetrically to the confuser, and at its end facing towards the neck, fastened irrigation nozzle, wherein the inlet diameter d converger ₁ and the outlet diameter of the diffuser ₃ d connected respectively to the inlet and outlet trubop gadgets, and the diffuser outlet connected to the discharge pipe is tangentially connected to the lower part of the cylindrical body of the direct-flow cyclone acting as a droplet eliminator, while the axes of the diffuser and the cyclone body are mutually perpendicular, the lower part of the cyclone body being connected to a conical hopper for draining the sludge, and the upper the part is connected to a conical chamber for the removal of purified gas, while the following aspect ratios of a circular Venturi pipe are aerodynamically optimal:
neck length l ₂ = 0.15 d ₂ ,
confuser length

,
diffuser length

,
where d ₂ is the diameter of the neck; α ₁ is the narrowing angle of the confuser, α ₁ = 15-28 °, α ₂ is the expansion angle of the diffuser, α ₂ = 6-8 °; moreover, at low speeds of gas and fine dust, Venturi pipes with an elongated neck l ₂ = (3-5) d _{2 are used} , characterized in that the nozzle of the irrigation system comprises a housing with a fitting rigidly connected to the housing coaxially located in the upper part of the housing and having a cylindrical hole for supplying fluid connected to a diffuser, an axisymmetric body and a fitting, and a sprayer connected perpendicular to the axis of the body and made in the form of at least three spokes is connected to the body in its lower part erforirovannogo disk. 2. The Venturi scrubber according to claim 1, characterized in that the nozzle atomizer disk is formed by two surfaces, one of which, facing the diffuser, is a curved surface, and the curve of the nth order is the line forming this surface, and the second is the plane. 3. The Venturi scrubber according to claim 1, characterized in that the spokes through which the nozzle atomizer disk is attached to the housing are arranged radially with respect to the axis of the housing and can be made straight and curved in shape. 4. The Venturi scrubber according to claim 1, characterized in that the perforation holes in the nozzle disk have axes intersecting at a point lying on the end surface of the housing and which is the center of the largest circumference of the diffuser. 5. The venturi scrubber according to claim 1, characterized in that the nozzle atomizer is made of solid materials, for example tungsten carbide.

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