GB2138692A - Dispersion of Liquids in Gases - Google Patents

Dispersion of Liquids in Gases Download PDF

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Publication number
GB2138692A
GB2138692A GB08407154A GB8407154A GB2138692A GB 2138692 A GB2138692 A GB 2138692A GB 08407154 A GB08407154 A GB 08407154A GB 8407154 A GB8407154 A GB 8407154A GB 2138692 A GB2138692 A GB 2138692A
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GB
United Kingdom
Prior art keywords
liquid
droplets
rotor
zinc
impeller
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Granted
Application number
GB08407154A
Other versions
GB8407154D0 (en
GB2138692B (en
Inventor
David Leslie Derham
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
ISC Smelting Ltd
Original Assignee
ISC Smelting Ltd
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Priority claimed from GB838309172A external-priority patent/GB8309172D0/en
Application filed by ISC Smelting Ltd filed Critical ISC Smelting Ltd
Priority to GB08407154A priority Critical patent/GB2138692B/en
Publication of GB8407154D0 publication Critical patent/GB8407154D0/en
Publication of GB2138692A publication Critical patent/GB2138692A/en
Application granted granted Critical
Publication of GB2138692B publication Critical patent/GB2138692B/en
Expired legal-status Critical Current

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Classifications

    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01F—MIXING, e.g. DISSOLVING, EMULSIFYING OR DISPERSING
    • B01F23/00—Mixing according to the phases to be mixed, e.g. dispersing or emulsifying
    • B01F23/20—Mixing gases with liquids
    • B01F23/23—Mixing gases with liquids by introducing gases into liquid media, e.g. for producing aerated liquids
    • B01F23/234—Surface aerating
    • B01F23/2342—Surface aerating with stirrers near to the liquid surface, e.g. partially immersed, for spraying the liquid in the gas or for sucking gas into the liquid, e.g. using stirrers rotating around a horizontal axis or using centrifugal force
    • B01F23/23421—Surface aerating with stirrers near to the liquid surface, e.g. partially immersed, for spraying the liquid in the gas or for sucking gas into the liquid, e.g. using stirrers rotating around a horizontal axis or using centrifugal force the stirrers rotating about a vertical axis
    • B01F23/234211—Stirrers thereof

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  • Chemical & Material Sciences (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Manufacture Of Metal Powder And Suspensions Thereof (AREA)

Abstract

Apparatus for dispersing a liquid, as droplets, in a gas, has at least one rotor mounted on a substantially vertical shaft dipping into a pool of the liquid, the rotor head being a multi-bladed helical impeller with a pitch/diameter ratio between 0.6 and 1.7. The apparatus is useful, inter alia, in condensing zinc vapour from permanent gases by means of a spray of molten lead/zinc droplets. <IMAGE>

Description

SPECIFICATION Dispersion of Liquids in Gases This invention relates to apparatus for the dispersion of liquids as droplets in gases for heat- or mass-transfer purposes. It is particularly applicable to the dispersion of molten metallurgical phases e.g. molten metals, alloys, mattes or slags into droplets in a gaseous phase for refining or condensation purposes. The dispersed metal may be used as a condensation medium e.g. as molten lead is used in the condensation of zinc vapour from a zinc blast furnace smelting process.
The smelting of zinc in a blast furnace is generally described in the paper "Application of the Blast Furnace to Zinc Smelting" by Morgan and Woods (Metallurgical Reviews 1971, 16 (156) November, pages 161-174). As will be seen from the schematic drawing on page 166 of this paper the top of the furnace shaft is connected, via a downwardly-directed duct, with the inlet of a "lead-splash condenser" in which the furnace gases are subjected, in several stages, to intense sprays of molten lead, generated by rotors, immersed in a pool or pools of molten lead. Typical prior-art rotor-heads are shown for example, in British patent specification 1,263,165 published 9.2.72.
It is an object of the present invention to provide apparatus for dispersing a liquid, as droplets, in a gas for heat- or mass-transfer purposes.
It is a further object of the invention to produce a spray of liquid droplets which is more intense, confined and of steeper trajectory than has been hitherto achieved.
This invention consists in apparatus for dispersing a liquid, as droplets, in a gas for heat- or masstransfer purposes, in which at least one spray envelope of liquid droplets is produced by rotation of a rotor head mounted on a substantially vertical shaft and at least partially immersed in the liquid, characterised in that the rotor head takes the form of a multi-bladed helical impeller, having a pitch/diameter ratio between 0.6 and 1.7.
The rotor-head according to the invention is based on the physical form of a marine propellor, although the blade shapes and other physical characteristics have been developed for the uses herein described.
Preferably the liquid is a molten metallurgical phase e.g. a molten metal, an alloy, a matte or a slag.
Preferably the liquid is a molten metal or alloy which is to be used to condense a metal vapour. In the case of zinc vapour the liquid would be a molten lead/zinc alloy.
Preferably the impeller is 3-bladed.
Preferably the pitch/diameter ratio of the impeller is between 0.6 and 1.3, more preferably between 0.7 and 0.9.
Preferably the circumferential tip speed of the impeller is within the range of 8m/sec-25m/sec for molten lead and the depth of immersion of the rotor below the static lead surface is preferably between 100 and 150 mm.
Various impeller designs have been tested but the best design appears to be a 3-bladed impeller with a pitch/diameter ratio of about 0.75-0.85. Typically such an impeller produces a spray pattern having a mean initial trajectory of about 500--600 to the horizontal, compared with a mean initial trajectory of about 300 to the horizontal for prior art rotors.
The spray pattern produced by apparatus according to the invention shows a good spray density and a weli-defined spray pattern boundary. Thus the spray produced by this type of apparatus is compact and of steeper trajectory.
It has also been shown that operation of rotor-heads in accordance with this invention requires a lower power consumption compared with conventional (prior art) rotors, as will be illustrated by the following figures: Conventional Rotor Vertical Spray Rotor (Prior Art) (According to Invention) Immersion Immersion (mm) Amps/Phase (mm) Amps/Phase 150 17.5 100 15.0 175 18.0 125 15.5 200 18.25 150 16.00 No load 15.0 No load 13.75 From the figures above it can be seen that the effective current taken to drive the rotor (load-no load) is in the range 2.5 to 3.25A., for the conventional rotor and 1.25 to 2.25A. for the rotor-head according to the invention.
Scaled-up by the density factor (molten lead/water) this represents effective currents, in lead, of 26-34A for the prior art rotor and 1 3-24A for the rotor-head according to this invention.
The invention will be further described by reference to the accompanying drawings in which Figure 1 a shows an outline of a spray pattern produced by a rotor-head (impeller) according to this invention, superimposed on a section through the first stage of a lead splash condenser and Figure 1 b shows an outline of the spray pattern produced by a prior art rotor-head used in a lead-splash condenser, in accordance with the teaching in British Patent No. 1,263,165, and Figure 2 shows a typical rotor-head. In Figures 1 a and 1 b, reference numeral 1 indicates the condenser, reference numeral 2 indicates the cross-over duct between the condenser and the furnace shaft, and reference numeral 3 indicates the inlet to the furnace shaft.
As will be observed from Figure 1 a the spray pattern produced by a rotor-head according to this invention is both more compact, more well defined and of steeper trajectory than that according to the prior art, and hence there is less tendency for the spray to reach into the cross-over duct between the furnace and the first stage of the condenser, resulting in a reduction in cross-over duct accretion (due to cooling of the brick work) and a reduction in furnace down-time.
Figure 2 shows a typical 3-bladed impeller for use in apparatus according to the invention.
Apparatus according to the invention may be used for purposes other than the condensation of metal vapour e.g. it may find application in metal spray-refining and in removal of impurities from molten metals by vaccum techniques.

Claims (14)

1. Apparatus for dispersing a liquid, as droplets, in a gas for heat- or mass-transfer purposes, in which at least one spray envelope of liquid droplets is produced by rotation of a rotor-head mounted on a substantially vertical shaft and at least partially immersed in the liquid; characterised in that the rotorhead takes the form of a multi-bladed helical impeller having a pitch/diameter ratio between 0.6 and 1.7.
2. Apparatus as claimed in claim 1 in which the liquid is a molten metal, an alloy, a matte or a slag.
3. Apparatus as claimed in claim 1 or 2 in which the liquid is a molten metal or alloy used to condense metal vapour.
4. Apparatus as claimed in claim 3 in which the liquid is a molten zinc/lead alloy used to condense zinc vapour.
5. Apparatus as claimed in claim 1 in which the impeller has 3 blades.
6. Apparatus as claimed in claim 1 or 5 in which the impeller is based on the physical form of a marine propellor.
7. Apparatus as claimed in claim 1 in which the pitch/diameter ratio is between 0.6 and 1.3.
8. Apparatus as claimed in claim 7 in which the pitch/diameter ratio is between 0.7 and 0.9.
9. Apparatus as claimed in claims 1 to 4 in which the circumferential tip speed of the rotor is within the range 8m/sec--25m/sec.
10. Apparatus as claimed in claim 4 or 9 in which the depth of immersion of the rotor below the static lead surface is between 100 and 150mm.
11. Apparatus as claimed in any preceding claim in which the mean initial trajectory of the liquid droplets is between 50 and 60C to the horizontal.
12. Apparatus for dispersing a liquid as droplets in a gas, substantially as hereinbefore described.
1 3. Apparatus for condensing zinc vapour from a gas mixture substantially as hereinbefore described.
14. Apparatus for condensing zinc vapour produced in a blast-furnace, in a spray of molten zinc/lead droplets as hereinbefore described.
GB08407154A 1983-04-05 1984-03-20 Dispersion of liquid in gases Expired GB2138692B (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
GB08407154A GB2138692B (en) 1983-04-05 1984-03-20 Dispersion of liquid in gases

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
GB838309172A GB8309172D0 (en) 1983-04-05 1983-04-05 Dispersion of liquids in gases
GB08407154A GB2138692B (en) 1983-04-05 1984-03-20 Dispersion of liquid in gases

Publications (3)

Publication Number Publication Date
GB8407154D0 GB8407154D0 (en) 1984-04-26
GB2138692A true GB2138692A (en) 1984-10-31
GB2138692B GB2138692B (en) 1986-05-14

Family

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Family Applications (1)

Application Number Title Priority Date Filing Date
GB08407154A Expired GB2138692B (en) 1983-04-05 1984-03-20 Dispersion of liquid in gases

Country Status (1)

Country Link
GB (1) GB2138692B (en)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4734235A (en) * 1986-11-24 1988-03-29 Holyoak H Ken Aerator

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB296248A (en) * 1928-01-09 1928-08-30 Pfaudler Co Inc Improvements in or relating to rotary agitators
GB1462005A (en) * 1974-01-23 1977-01-19 Alfa Laval Ab Device for supplying gas to a liquid and stirring the liquid
GB1472179A (en) * 1973-08-22 1977-05-04 Ind Ontwikkelingsmaatschappij Rotor
GB1527895A (en) * 1974-10-17 1978-10-11 Union Carbide Corp Surface aeration system with controlled aerator submergence
GB2026092A (en) * 1978-06-30 1980-01-30 Nederlandse Appl Scient Res Bladed rotor

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB296248A (en) * 1928-01-09 1928-08-30 Pfaudler Co Inc Improvements in or relating to rotary agitators
GB1472179A (en) * 1973-08-22 1977-05-04 Ind Ontwikkelingsmaatschappij Rotor
GB1462005A (en) * 1974-01-23 1977-01-19 Alfa Laval Ab Device for supplying gas to a liquid and stirring the liquid
GB1527895A (en) * 1974-10-17 1978-10-11 Union Carbide Corp Surface aeration system with controlled aerator submergence
GB2026092A (en) * 1978-06-30 1980-01-30 Nederlandse Appl Scient Res Bladed rotor

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4734235A (en) * 1986-11-24 1988-03-29 Holyoak H Ken Aerator

Also Published As

Publication number Publication date
GB8407154D0 (en) 1984-04-26
GB2138692B (en) 1986-05-14

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Legal Events

Date Code Title Description
732E Amendments to the register in respect of changes of name or changes affecting rights (sect. 32/1977)
PCNP Patent ceased through non-payment of renewal fee

Effective date: 20000320