AU606494B2

AU606494B2 - Device for supplying scrubbing liquid in a radial flow scrubber

Info

Publication number: AU606494B2
Application number: AU28361/89A
Authority: AU
Inventors: Gerhard Mack; Reinhold Schneider
Original assignee: Metallgesellschaft AG
Current assignee: GEA Group AG
Priority date: 1988-01-12
Filing date: 1989-01-11
Publication date: 1991-02-07
Anticipated expiration: 2009-01-11
Also published as: ES2029877T3; EP0324200B1; JPH01218616A; DE3800604A1; ZA89224B; AU2836189A; EP0324200A1; DE3868042D1; ATE71851T1

Abstract

A device is proposed in which the scrubbing liquid is not injected into the gas stream by conventional atomisation jets, but by a surface contact of the gas stream with a liquid store, thus avoiding uncontrolled vortices in the liquid-laden gas stream, and deposition and encrustation by sticking and/or clumping dusts are excluded. <IMAGE>

Description

So., of Company and Signatures Of i.s officers as prescribed by MvC 0 ,izAcicl5o I1 1/ 01 /8191 Stephen K. Plymin Registered Patent Attorney

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COMMONWEALTH OF AUSTRAL '0'0649 4110 PATENTS ACT 1952.69 COMPLETE SPECIFICATION

(ORIGINAL)

Class I t. Class Application Number: Lodged: Complete Specification Lodged: 4 Accepted: Published: Priority: Related Art: This document contains the aicndmenits made -under Section 49 and is correct for printing. -Name of Applicant: Addiress of Applicant: :4tal Inventor: Address for Service: METALLGESELLSCHAFT AKTIENGESELLSCHAFT Reuterweg 14, D-6000 Frankfurt/Main, Federal Republic of Germany GERHARD MACK, REINHOLD SCHNEIDER EDWD. WATE RS SONS, 50 QUEEN STREET, MELBOURNE, AUSTRALIA, 3000.

Complete Specification for the invention entitled: DEVICE FOR SUPPLYING SCRUBBING LIQUID IN A RADIAL FLOW

SCRUBBER

The following statement is a full description of this invention, including the best method of performing it known to*- -2- DEVICE FOR SUPPLYING SCRUBBING LIQUID IN A RADIAL FLOW SCRUBBER

DESCRIPTION

This invention relates to a device for supplying scrubbing liquid in a radial flow scrubber, in which the radial gap is defined by a top horizontal edge of a gas-guiding device and an opposite bottom horizontal edge of the vertically adjustable liquid-supplying device.

Radial flow scrubbers are known in various forms 15 (see Stahl und Eisen, 86 (1966), pages 399-406; Ullmann, 4th edition (1972), volume 2, pages 227-235, particularly page go 234). They are used when gases at high rates are to be dedusted and cooled at the same time. For an adjustment to different operating conditions the radial gap defined by two mutually opposite, annular components can be changed in that oo ~one of the two annular components is displaced at right 0.:0 angles to the plane of the radial gap. In that manner the gas velocity in the gap cross-section will be controlled so that the purification of the gas will be strongly influenced. Higher gas velocities will generally result in 0*@OSO S higher separation rates but will involve a higher pressure s drop. Thus, the effectiveness and economy of the gas-purifying process tend to change in mutually opposing 30 senses so that it is not possible to state in general an optimum gap cross-section or an optimum gas velocity, but such optimum can be stated only for specific applications.

Another significant controlling variable in the purification of gases by means of radial flow scrubbers is the rate at which the scrubbing liquid must be supplied if a specified cooling of the gas and purifying action are to be achieved. In that respect it is also impossible to furnish -3information which is generally applicable because the proportions in which the scrubbing liquid is to be contained in the gas stream in the form of fine droplets and in the form of vapor can be determined only for specific general conditions.

Independently of the above-mentioned controlling variables, the purification of gases which contain sticky and/or caking dusts has often given rise to problems when the scrubbing liquid is injected into the radial flow scrubber under high pressure. In that case the formation of uncontrolled vortices cannot be avoided and in such vortices the dust particles will be bonded to the liquid droplets .upstream of the radial gap. This will result in a sticky 1 and/or caking composition, which cannot entirely be S entrained by the gas stream. That part of said composition 6. which remains in the radial flow scrubber will form deposits :I"o and crusts wherever the gas stream cannot entrain deposits.

Such deposits and crusts may have a considerable adverse effect on the operation of a radial flow scrubber. In many cases the flow areas are so constricted by deposits within a S0short time that an economical operation is no longer aO..

possible because the pressure drops are excessive.

Prolonged or frequent downtimes required for a removal of 25 the deposits are often intolerable and in such case radial 25 S flow scrubbers cannot be used at all. In most cases, the adverse effects of sticky and/or caking dusts will not be observed until a radial flow scrubber is in operation. In Ssuch cases the operator and the supplier of such plant may S suffer very considerable financial losses.

For this reason it is an object of the present invention to design a device of the kind hereinbefore described so that the described deposits and crusts which would result from uncontrolled vortices formed by the scrubbing liquid as it enters a radial flow scrubber can be prevented and radial flow scrubbers can be economically operated even for the purification of gases which contain sticky and/or caking dusts.

AP17 LI -4- That object is accomplished by a liquid-supplying device comprising a) a circular ring-shaped flat bottom, which is provided with an upwardly facing, cylindrical outer boundary, which constitutes the bottom edge of the radial gap, and with a downwardly facing cylindrical inner boundary, which carries a connecting flange, b) a plate, which is connected to the connecting flange and is provided with a central tubular port for supplying the scrubbing liquid, c) a swirler for imparting a velocity component to the scrubbing liquid in the circumferential direction which is mounted on top of the plate and has a flat top cover formed 0O*@ with a central through opening, 15 Sd) a conical cover for guiding the gas which is supported on the flat cover by a tube, and 'O e) a cylinder, which is mounted on top of the plate and has an outside diameter that is somewhat smaller than 20 the largest diameter of the conical cover.

A further feature of the invention resides in that *mI the conical cover has at its top a cylindrical opening, oooo which is covered by a smaller conical cover, which defines a gap with the conical cover.

25 In the operation of the liquid-supplying device in accordance with the invention the scrubbing liquid is supplied through the central tubular port into the bowl which is constituted by the circular ring-shaped, flat bottom and the cylin"rical outer boundary and is entrained 3 by the downwardly inflowing gas, which exits through the radial gap. The conical cover serves to guide the gas. A difference from conventional liquid-supplying devices resides in that the scrubbing liquid is not injected under high pressure into the gas stream but is entrained by the gas from a large-area supply space so that there is no possibility of a formation of uncontrolled vortices in which a stocky and/or caking composition could be formed by droplets of scrubbing liquid and particles of dust. The

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Ir -4adevice in accordance with the invention has the same energy requirement as conventional liquid-supplying devices but it affords the advantage that the scrubbing liquid and the gas stream are mixed in such a manner that uncontrolled vortices cannot be formed and the conditions of flow upstream of the 0 4« 9e US S9 0 *005 00@S 9 *0 0 0 .4/MELB 5/C.K.(VAX EK) o i' WINU i ™A 59539? t o a 0 59..

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a90 radial gap will not permit a deposition of a sticky and/or caking composition 'that consists of dust and scrubbing liquid. Any vortices or stagnant or almost stagnant regions formed in the gas flow space above the surface of the liquid will contain only dry dust-containing gases, which cannot cause a formation of deposits or crusts. The scrubbing liquid is entrained by the gas stream adjacent to the surface of the scrubbing liquid, only at the outer boundary of the gas stream, where deposits cannot be formed in any case before the radial gap is reached.

Further details and advantages will be explained more in detail with reference to the illustrative embodiment shown in Figure 1.

The device in accordance with the invention for 15 supplying scrubbing liquid in a radial flow scrubber essentially consists of a circular ring-shaped, flat.bottom 1 that is provided with an upwardly facing,\eaodrdcouter boundary 2, which defines the bottom edge of the radial gap,, and with a downwardly facing cylindrical inner boundary 3, which carries a connecting flange 14. A plate 4 provided with a central tubular port 5 is connected to the connecting flange 14. A swirler 6 is mounted on top of the plate 4 and has a flat top cover 7, which is formed with a central through opening 16. By means of a tube 9, the cover 7 supports a conical cover 8. A cylinder 10 is mounted on top of the plate 4 and has an outside diameter which is somewhat smaller than the largest diameter of the conical cover 8.

In accordance with a further feature of the invention, defined in claim 2, the conical cover 8 has at its top a cylindrical opening 11, which is covered by a smaller conical cover 12, which defines with the cover 8 ga gap 13.

A part of the gas-guiding device of a radial flow scrubber is also shown and has an annular end portion which defines the top edge of the radial gap. The entire device for supplying scrubbing liquid can be raised and lowered in known manner in order to change the radial gap.

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-6- During the operation of the radial flow scrubber, scrubbing liquid is supplied through the central tubular port 5 to the device in accordance with the invention for supplying liquid. A major part of the scrubbing liquid is delivered through the swirler 6 and the cylinder 10 into the open-topped bowl which is constituted by the flat bottom 1 and the outer boundary 2 and radially emerges from the gap that is defined by the cover 8 and the cylinder 10. Owing to the swirler 6 the scrubbing liquid has also a velocity component in the circumferential direction.

A minor part of the scrubbing liquid which is supplied rises through the central through opening 16 in the tube 9 to a higher level and enters the gas space through the cylindrical opening 11 and through the gap 13 between 15 the cover 8 and the cover 12 and flows downwardly in the gas space over the cover 8.

When the radial flow scrubber is not supplied with a gas stream, a liquid surface on the level of the top rim of the outer boundary 2 will be formed in the bowl formed by 20 the flat bottom 1 and the boundary 2. Upon a further supply of liquid that outer boundary 2 will constitute an overflow.

When the radial flow scrubber is supplied with a gas stream, as is intended, that gas stream will be outwardly deflected by the surface of the liquid toward the radial gap and a 25 downwardly convex liquid surface will be formed. The scrubbing liquid will be entrained by the gas stream at the interface between the gas stream and the liquid surface, also on the liquid-covered cover 8, and will be carried by the gas stream toward the radial gap. The division of the scrubbing liquid into minute droplets will be effected in the radial gap and in a small region downstream of the radial gap. As a result, a formation of uncontrolled vortices and a deposition of the stocky and/or caking dust-liquid mixture which have been observed where conventional liquid-supplying devices are used will be avoided. No deposits can form on the cover 12, which is swept only by the dry gas stream.

-7 1 14 -7- It has surprisingly been found that for a supply of the scrubbing liquid into a radial flow scrubber it is not necessary to use the known injecting or atomizing means which are operated under a high liquid pressure. Liquid at the required rate can readily b e introduced into the gas stream merely by the contact between the gas stream and a sufficiently large liquid surface area. Whereas the gas press-ure drop is somewhat increased in the device in accordance with the invention because the required division into minute droplets is effected in the radial gap, that higher pressure drop is compensated in the overall balance by the energy required to handle the liquid.

The liquid-supplying device in accordance with the invention permits a use of radial flow scrubbers also for S* 15 the purification of gases which contain sticky and caking .O dusts because uncontrolled vortices upstream of the radial gap cannot occur or can occur only in the unmoistened, dry 00 e gas stream, which cannot effect a formation of deposits or crusts.

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Claims

1. A device for supplying scrubbing liquid in a radial flow scrubber, in which the radial gap is defined by a top horizontal edge of a gas-guiding device and an opposite bottom horizontal edge of the vertically adjustable liquid-supplying device, comprising a) a circular ring-shaped flat bottom which is tests: provided with an upwardly facing, cylindrical outer boundary *which constitutes the bottom edge of the radial gap, and with a downwardly facing cylindrical inner boundary which **0ee 0 carries a connecting flange, of 0 0 b) a plate which is connected to the connecting flange and is provided with a central tubular port for supplying the scrubbing liquid, C) a swirler for imparting a velocity component to the scrubbing liquid in the circumferential direction, which is mounted on top of the plate and has a flat top cover formed with a central through opening, a conical cover for guiding the gas, which is supported on the flat cover by a tube and 0 e) a cylinder which is mounted on top of the plate and has an outside diameter that is somewhat smaller than the largest diameter of the conical cover.

2. A device according to claim 1, characterized in that the conical cover for guiding the gas has at its top aV cylindrical opening which is covered by a smaller conical cover which defines a gap with the conical cover. 4 J -9-

3. A radial flow scrubber including the device of claim 1 or claim 2.

4. A device for supplying scrubbing liquid in a radial flow scrubber substantially as hereinbefore described with reference to Figure 1. DATED this 24th day of October, 1990 METALLGESELLSCHAFT AKTIENGESELLSCHAFT 0 9 doe* WATERMARK Patent Trademark Attorneys "The Atrium" 290 Burwood Road *Hawthorn Victoria 3122 AUSTRALIA 0 0 1.4/MELB

5/C.K.(VAX EK)