WO1992007651A1 - Method and device for mixing a pulverulent material with liquid - Google Patents

Method and device for mixing a pulverulent material with liquid Download PDF

Info

Publication number
WO1992007651A1
WO1992007651A1 PCT/SE1991/000717 SE9100717W WO9207651A1 WO 1992007651 A1 WO1992007651 A1 WO 1992007651A1 SE 9100717 W SE9100717 W SE 9100717W WO 9207651 A1 WO9207651 A1 WO 9207651A1
Authority
WO
WIPO (PCT)
Prior art keywords
liquid
conveying path
layer
mixing
spread
Prior art date
Application number
PCT/SE1991/000717
Other languages
French (fr)
Inventor
Sven Ragnarsson
Original Assignee
ABB Fläkt AB
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
Application filed by ABB Fläkt AB filed Critical ABB Fläkt AB
Publication of WO1992007651A1 publication Critical patent/WO1992007651A1/en

Links

Classifications

    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01F—MIXING, e.g. DISSOLVING, EMULSIFYING OR DISPERSING
    • B01F33/00—Other mixers; Mixing plants; Combinations of mixers
    • B01F33/80—Mixing plants; Combinations of mixers
    • B01F33/82—Combinations of dissimilar mixers
    • B01F33/821—Combinations of dissimilar mixers with consecutive receptacles

Definitions

  • the present invention relates to a method for mixing a pulverulent material with liquid, the pulverulent mate ⁇ rial and the liquid being mechanically intermixed in a mixing unit.
  • the invention also concerns a device designe for implementing the method and including such a mixing unit.
  • impurities e.g. acid components, such as hydrochloric acid and sulphur oxide, in the flue gases.
  • the flue gases are con ⁇ ducted through a separator, such as an electrostatic precipitator or a bag filter, from which residual pro ⁇ ducts, such as calcium chloride, calcium sulphite and calcium sulphate, are obtained in the form of a pulver- ulent and dry, and consequently dusting, material.
  • a separator such as an electrostatic precipitator or a bag filter
  • residual pro ⁇ ducts such as calcium chloride, calcium sulphite and calcium sulphate
  • the material is carried by screw conveyors or the like from the separator to a silo for intermediate storage.
  • the pulverulent material in the silo is then loaded on a lorry for transportation to a refuse tip for final stor- age. So as not to dust when transported to and stored at the refuse tip, the material is fed out via a mixing device in which it is mixed with water.
  • the mixing device usually has two parallel mixing and conveying screws for mechanical intermixing of the pulverulent material and the water.
  • the pulverulent material is introduced into the mixing device at the inlet end of the screws, and the water is injected into the mixing device in the form of droplets by means of nozzles provided above the screws. Not only the pulverulent material is then sprayed, but also the screws and other parts of the device, and the pulverulent material will therefore, especially if hygroscopic, stick to the sprayed screws etc, which thus are covered with growing layers of coating. Naturally, these coatings reduce the capacity of the mixing device and the mixing effect. In addition, the coatings are difficult to remove.
  • One object of the present invention is, therefore, to provide a method for mixing a pulverulent material with liquid without any of the above inconveniences.
  • this object is achieved by a method which is of the type mentioned in the intro- duction to this specification and which is characterised in that the pulverulent material is spread in an even layer on a substantially horizontal conveying path, that the liquid is distributed over the spread layer of mate ⁇ rial, and that the layer of material thus supplied with liquid is introduced into the mixing unit for mechanical intermixing.
  • Another object of the invention is to provide a simple device for implementing the method.
  • this object is achieved by a device which includes a mixing unit for mechanical intermixing of the pulverulent material and the liquid an which is characterised by a substantially horizontal con ⁇ veying path provided above the mixing unit, an inlet mean for spreading the pulverulent material in an even layer o the conveying path, and an inlet means for distributing the liquid over the spread layer of material, said convey ing path being adapted to introduce the layer of material thus supplied with liquid into the mixing unit.
  • the conveying path suitably consists of an upper run of an endless conveying belt.
  • the inlet means for the pulverulent material has a downpipe whose lower end is located close to the conveying path over the main part of its circumference but has a front circumferential portion as seen in the direction of travel of the conveying path, which is located at a slight distance from the conveying path, thereby forming a gap whose height determines the thickness of the layer of material spread on the conveyi path.
  • the height of the gap is adjustable by means of a vertically adjustable doori
  • the inlet means for the liquid has a downpipe whose lower end is located at a distance above the conveying path, and a metal sheet arranged between the downpipe and the conveying path to distribute the liquid over the entire width of the layer of material spread on the conveying path.
  • the mixing unit has a set of first mixing and conveying screws adapt ed to convey the mixture of material and liquid towards a outlet, and a set of second mixing and conveying screws which are parallel with, and disposed below, the first screws and which are adapted to convey the mixture of material and liquid away from the outlet.
  • FIG. 1 is a schematic longitudinal section of a device according to the invention.
  • Fig. 2 is a schematic cross-section taken along the line II-II in fig. 1.
  • the device illustrated in the drawing has a housing with an upper portion la and a lower portion lb of less width than the upper portion (see Fig. 2).
  • An endless conveying belt 2 is arranged in the upper portion la of the housing 1.
  • the conveying belt 2 has an upper run 2' forming a horizontal conveying path which travels from one end of the housing 1 to the other.
  • An inlet 3 for the pulverulent material is provided at the inlet end of the conveying path 2' , and is arrange to spread the pulverulent material in an even layer 4 on the conveying path 2'.
  • An inlet 5 for the liquid, e.g. water, is provided after the inlet 3 (as seen in the direction of travel Pi of the conveying path 2'), and is arranged to distribute the liquid over the spread layer o material 4.
  • the inlet 3 for the pulverulent material has a down ⁇ pipe 6 whose lower end is located close to the conveying path 2' over the main part of its circumference but has a front circumferential portion, as seen in the direction of travel PI of the conveying path, which is located at a slight distance from the conveying path 2' , thereby form ⁇ ing a gap 7 whose height determines the thickness of the layer of material 4 spread on the conveying path.
  • the downpipe 6 has a vertically adjustable door 6' for adjust- ing the height of the gap 7 and, consequently, the thick ⁇ ness of the layer of material 4.
  • the inlet 5 for the liquid has a downpipe 8 whose lower end is located at a distance above the conveying path 2' , and a metal sheet 9 which is arranged between the downpipe and the conveying path and is fixed to the down ⁇ pipe and which is adapted to distribute the liquid over the entire width of the layer of material 4 spread on the conveying path.
  • the metal sheet 9 has an upwardly bent rear edge 9' and upwardly bent side edges 9". In the direction of travel PI of the conveying path 2' , the width of the metal sheet 9 increases and the distance to the conveying path 2' decreases.
  • a metal sheet 9 when the liquid to be distrib ⁇ uted over the layer of material 4 spread on the conveying path 2' is a viscous liquid, such as sludge or slurry of e.g. water and salts of alkali metals and/or alkali earth metals, metal sulphides and metal hydroxides.
  • a viscous liquid such as sludge or slurry of e.g. water and salts of alkali metals and/or alkali earth metals, metal sulphides and metal hydroxides.
  • a mixing unit 10 provided in the housing 1 below the conveying belt 2 has two parallel upper mixing and convey ing screws 11 and two lower mixing and conveying screws 1 which are parallel with the upper screws 11.
  • the lower screws 12 are arranged in the lower portion lb of the housing 1, and the upper screws 11 are arranged above the lower screws 12 in the upper portion la of the housing 1, The diameter of the upper screws 11 is larger than that o the lower screws 12.
  • the layer of material 4' which has been supplied wit liquid and is fed on the conveying path 2' leaves the pat 2' at the outlet end thereof, i.e. the right end in Fig.
  • a scraper 13 is provided at the outlet end of the conveying path 2'.
  • the upper screws 11 feed the mixture of material and liquid in the direction indicated by the arrow P2 towards the outlet 14 of the housing 1, and the lower mixing and conveying screws 12 feed the mixture of material and liquid in the opposite direction P3, away from the outlet 14.

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  • Chemical & Material Sciences (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Mixers Of The Rotary Stirring Type (AREA)

Abstract

In a method for mixing a pulverulent material with liquid, the pulverulent material is spread in an even layer (4) on a horizontal conveying path (2'), whereupon the liquid is distributed over the spread layer of material (4). Then, the layer of material (4') thus supplied with liquid is introduced into a mixing unit (10) for mechanical intermixing. A device for implementing the method includes a mixing unit (10) for mechanical intermixing of the pulverulent material and the liquid. A horizontal conveying path (2') is provided above the mixing unit. Further, an inlet (3) is arranged to spread the pulverulent material in an even layer (4) on the conveying path (2'), and an inlet (5) is arranged to distribute the liquid over the layer of material (4). The conveying path (2') is adapted to introduce the layer of material (4') thus supplied with liquid into the mixing unit (10).

Description

METHOD AND DEVICE FOR MIXING A PULVERULENT MATERIAL WITH
LIQUID
The present invention relates to a method for mixing a pulverulent material with liquid, the pulverulent mate¬ rial and the liquid being mechanically intermixed in a mixing unit. The invention also concerns a device designe for implementing the method and including such a mixing unit. In a prior-art method for cleaning flue gases from e.g. a refuse-fired boiler, the flue gases are conducted through a reactor, into which lime, optionally together with water, is injected to react with impurities, e.g. acid components, such as hydrochloric acid and sulphur oxide, in the flue gases. Then, the flue gases are con¬ ducted through a separator, such as an electrostatic precipitator or a bag filter, from which residual pro¬ ducts, such as calcium chloride, calcium sulphite and calcium sulphate, are obtained in the form of a pulver- ulent and dry, and consequently dusting, material. The material is carried by screw conveyors or the like from the separator to a silo for intermediate storage. The pulverulent material in the silo is then loaded on a lorry for transportation to a refuse tip for final stor- age. So as not to dust when transported to and stored at the refuse tip, the material is fed out via a mixing device in which it is mixed with water. The mixing device usually has two parallel mixing and conveying screws for mechanical intermixing of the pulverulent material and the water. The pulverulent material is introduced into the mixing device at the inlet end of the screws, and the water is injected into the mixing device in the form of droplets by means of nozzles provided above the screws. Not only the pulverulent material is then sprayed, but also the screws and other parts of the device, and the pulverulent material will therefore, especially if hygroscopic, stick to the sprayed screws etc, which thus are covered with growing layers of coating. Naturally, these coatings reduce the capacity of the mixing device and the mixing effect. In addition, the coatings are difficult to remove. One object of the present invention is, therefore, to provide a method for mixing a pulverulent material with liquid without any of the above inconveniences.
According to the invention, this object is achieved by a method which is of the type mentioned in the intro- duction to this specification and which is characterised in that the pulverulent material is spread in an even layer on a substantially horizontal conveying path, that the liquid is distributed over the spread layer of mate¬ rial, and that the layer of material thus supplied with liquid is introduced into the mixing unit for mechanical intermixing.
Another object of the invention is to provide a simple device for implementing the method.
According to the invention, this object is achieved by a device which includes a mixing unit for mechanical intermixing of the pulverulent material and the liquid an which is characterised by a substantially horizontal con¬ veying path provided above the mixing unit, an inlet mean for spreading the pulverulent material in an even layer o the conveying path, and an inlet means for distributing the liquid over the spread layer of material, said convey ing path being adapted to introduce the layer of material thus supplied with liquid into the mixing unit.
The conveying path suitably consists of an upper run of an endless conveying belt.
In a preferred embodiment, the inlet means for the pulverulent material has a downpipe whose lower end is located close to the conveying path over the main part of its circumference but has a front circumferential portion as seen in the direction of travel of the conveying path, which is located at a slight distance from the conveying path, thereby forming a gap whose height determines the thickness of the layer of material spread on the conveyi path. Preferably, the height of the gap is adjustable by means of a vertically adjustable doori
In a preferred embodiment, the inlet means for the liquid has a downpipe whose lower end is located at a distance above the conveying path, and a metal sheet arranged between the downpipe and the conveying path to distribute the liquid over the entire width of the layer of material spread on the conveying path. In a preferred embodiment of the device, the mixing unit has a set of first mixing and conveying screws adapt ed to convey the mixture of material and liquid towards a outlet, and a set of second mixing and conveying screws which are parallel with, and disposed below, the first screws and which are adapted to convey the mixture of material and liquid away from the outlet.
The invention will be described in more detail below reference being had to the accompanying drawing, in which Fig. 1 is a schematic longitudinal section of a device according to the invention, and
Fig. 2 is a schematic cross-section taken along the line II-II in fig. 1.
The device illustrated in the drawing has a housing with an upper portion la and a lower portion lb of less width than the upper portion (see Fig. 2).
An endless conveying belt 2 is arranged in the upper portion la of the housing 1. The conveying belt 2 has an upper run 2' forming a horizontal conveying path which travels from one end of the housing 1 to the other. An inlet 3 for the pulverulent material is provided at the inlet end of the conveying path 2' , and is arrange to spread the pulverulent material in an even layer 4 on the conveying path 2'. An inlet 5 for the liquid, e.g. water, is provided after the inlet 3 (as seen in the direction of travel Pi of the conveying path 2'), and is arranged to distribute the liquid over the spread layer o material 4. The inlet 3 for the pulverulent material has a down¬ pipe 6 whose lower end is located close to the conveying path 2' over the main part of its circumference but has a front circumferential portion, as seen in the direction of travel PI of the conveying path, which is located at a slight distance from the conveying path 2' , thereby form¬ ing a gap 7 whose height determines the thickness of the layer of material 4 spread on the conveying path. The downpipe 6 has a vertically adjustable door 6' for adjust- ing the height of the gap 7 and, consequently, the thick¬ ness of the layer of material 4.
The inlet 5 for the liquid has a downpipe 8 whose lower end is located at a distance above the conveying path 2' , and a metal sheet 9 which is arranged between the downpipe and the conveying path and is fixed to the down¬ pipe and which is adapted to distribute the liquid over the entire width of the layer of material 4 spread on the conveying path. The metal sheet 9 has an upwardly bent rear edge 9' and upwardly bent side edges 9". In the direction of travel PI of the conveying path 2' , the width of the metal sheet 9 increases and the distance to the conveying path 2' decreases. It is especially convenient to use such a metal sheet 9 when the liquid to be distrib¬ uted over the layer of material 4 spread on the conveying path 2' is a viscous liquid, such as sludge or slurry of e.g. water and salts of alkali metals and/or alkali earth metals, metal sulphides and metal hydroxides.
A mixing unit 10 provided in the housing 1 below the conveying belt 2 has two parallel upper mixing and convey ing screws 11 and two lower mixing and conveying screws 1 which are parallel with the upper screws 11. The lower screws 12 are arranged in the lower portion lb of the housing 1, and the upper screws 11 are arranged above the lower screws 12 in the upper portion la of the housing 1, The diameter of the upper screws 11 is larger than that o the lower screws 12. The layer of material 4' which has been supplied wit liquid and is fed on the conveying path 2' leaves the pat 2' at the outlet end thereof, i.e. the right end in Fig.
I, and drops onto the upper mixing and conveying screws 1 in the mixing unit 10. A scraper 13 is provided at the outlet end of the conveying path 2'. The upper screws 11 feed the mixture of material and liquid in the direction indicated by the arrow P2 towards the outlet 14 of the housing 1, and the lower mixing and conveying screws 12 feed the mixture of material and liquid in the opposite direction P3, away from the outlet 14. The upper screws
II, whose feeding capacity is greater than that of the lower screws 12, discharge through the outlet 14 a pul¬ verulent material which is thoroughly intermixed with liquid. The relationship between the feeding capacity of the upper screws 11 and that of the lower screws 12, i.e. the feeding capacities in directions P2 and P3, respec¬ tively, can be adjusted by altering the rotational speed of the screws 11 and 12. Two pairs of mixing and conveyin screws 11 and 12 give a much more homogeneous mixture tha would only one pair.

Claims

1. Method for mixing a pulverulent material with liquid, the pulverulent material and the liquid being mechanically intermixed in a mixing unit (10), c h a - r a c t e r i s e d in that the pulverulent material is spread in an even layer (4) on a substantially horizontal conveying path (2'), that the liquid is distributed over the spread layer of material (4), and that the layer of material (4' ) thus supplied with liquid is introduced into the mixing unit (10) for mechanical intermixing.
2. Device for implementing the method of claim 1 for mixing a pulverulent material with liquid, said device including a mixing unit (10) for mechanical intermixing o the pulverulent material and the liquid, c h a r a c ¬ t e r i s e d by a substantially horizontal conveying path (2') provided above the mixing unit (10), an inlet means (3) for spreading the pulverulent material in an even layer (4) on the conveying path (2' ), and an inlet means (5) for distributing the liquid over the spread layer of material (4), said conveying path (2' ) being adapted to introduce the layer of material (4' ) thus supplied with liquid into the mixing unit (10).
3. The device of claim 2, c h a r a c t e r i s e d in that the conveying path (2' ) consists of an upper run of an endless conveying belt (2).
4. The device of claim 2 or 3, c h a r a c ¬ t e r i s e d in that the inlet means (3) for the pulver ulent material has a downpipe (6) whose lower end is located close to the conveying path (2' ) over the main part of its circumference but has a front circumferential portion, as seen in the direction of travel (PI) of the conveying path, which is located at a slight distance fro the conveying path (2'), thereby forming a gap (7) whose height determines the thickness of the layer of material (4) spread on the conveying path.
5. The device of claim 4, c h a r a c t e r i s e d in that the height of the gap (7) is adjustable by means of a vertically adjustable door (6')»
6. The device of any one of claims 2-5, c h a - r a c t e r i s e d in that the inlet means (5) for the liquid has a downpipe (8) whose lower end is located at a distance above the conveying path (2' ), and a metal sheet (9) arranged between the downpipe and the conveying path to distribute the liquid over the entire width of the layer of material (4) spread on the conveying path.
7. The device of any one of claims 2-6, c h a ¬ r a c t e r i s e d in that the mixing unit (10) has a set of first mixing and conveying screws (11) adapted to convey the mixture of material and liquid towards (P2) an outlet (14), and a set of second mixing and conveying screws (12) which are parallel with, and disposed below, the first screws and which are adapted to convey the mixture of material and liquid away from (P3) the outlet (14).
PCT/SE1991/000717 1990-10-30 1991-10-25 Method and device for mixing a pulverulent material with liquid WO1992007651A1 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
SE9003454A SE9003454L (en) 1990-10-30 1990-10-30 SEAT AND DEVICE FOR MIXING A POWDER-MATERIAL AND SCIENCE
SE9003454-7 1990-10-30

Publications (1)

Publication Number Publication Date
WO1992007651A1 true WO1992007651A1 (en) 1992-05-14

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ID=20380768

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/SE1991/000717 WO1992007651A1 (en) 1990-10-30 1991-10-25 Method and device for mixing a pulverulent material with liquid

Country Status (3)

Country Link
AU (1) AU8861791A (en)
SE (1) SE9003454L (en)
WO (1) WO1992007651A1 (en)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US7235194B2 (en) 1996-11-12 2007-06-26 California Institute Of Technology Two-photon or higher-order absorbing optical materials for generation of reactive species

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE1045372B (en) * 1953-06-19 1958-12-04 Krauss Maffei Imp G M B H & Co Mixer for bulk goods with a high dry content
DE1920970A1 (en) * 1968-04-26 1970-09-17 Manuf D Engrais Organiques Meo Manufacturing process for a powdery or granular mixture and device for applying the process
DE1607775A1 (en) * 1966-12-12 1972-03-16 Masuo Hosokawa Continuously working mixer

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE1045372B (en) * 1953-06-19 1958-12-04 Krauss Maffei Imp G M B H & Co Mixer for bulk goods with a high dry content
DE1607775A1 (en) * 1966-12-12 1972-03-16 Masuo Hosokawa Continuously working mixer
DE1920970A1 (en) * 1968-04-26 1970-09-17 Manuf D Engrais Organiques Meo Manufacturing process for a powdery or granular mixture and device for applying the process

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
DERWENT'S ABSTRACT, No. 360 39 C/20; & SU,A,686 744, publ. week 8020. *

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US7235194B2 (en) 1996-11-12 2007-06-26 California Institute Of Technology Two-photon or higher-order absorbing optical materials for generation of reactive species

Also Published As

Publication number Publication date
SE9003454L (en) 1992-05-01
SE9003454D0 (en) 1990-10-30
AU8861791A (en) 1992-05-26

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