WO1997013573A1

WO1997013573A1 - Apparatus for and a method of removing gaseous pollutants

Info

Publication number: WO1997013573A1
Application number: PCT/GB1996/002495
Authority: WO
Inventors: Sidney Wedgwood
Original assignee: Sidney Wedgwood
Priority date: 1995-10-13
Filing date: 1996-10-11
Publication date: 1997-04-17
Also published as: GB9521027D0; AU7224296A

Abstract

Apparatus for removing gaseous pollutants from air comprises a unit having a plurality of regularly spaced horizontally or vertically oriented disc form members (5). Polluted air is fed to the member (5) simultaneously with water or other solvent while the members are rotated by an electric motor (11) at high speed. This atomises the water which absorbs pollutants from the gas in its passage between adjacent members (5). Polluted water drains down to a tank (2) from which it can be removed while the cleaned gas is exhausted through a pipe (17). Formations on the members (5) promote mixing of pollutants and solvent.

Description

APPARATUS FOR AND A METHOD OF REMOVING GASEOUS POLLUTANTS

The present invention relates to apparatus for and a method of

removing gaseous pollutants from a gas such as air.

The invention is particularly but not exclusively applicable to the

removal of hydrogen fluoride. This is produced from fluoride found naturally

in clay in the production of pottery from that clay. Fluoride scrubbers are

available but these are complicated and expensive to install.

According to one aspect of the invention there is provided, apparatus

for removing gaseous pollutants from gas comprising means for supplying

a liquid solvent to a unit comprising one or more members, means for

moving the said one or more members, in order to create spray comprising

a mu-tiplicitγ of droplets from the solvent supplied and means for supplying

polluted air to the unit to mix with the droplets of the spray in order to

remove pollutants from the gas, means for removing solvent bearing the

pollutants from the unit and means for exhausting gas from which the pollutants have been removed.

According to another aspect of the present invention there is provided

a method of removing pollutants from gas comprising the steps of supplying

a liquid solvent, producing spray of droplets of solvent, passing polluted

gas through the spray so that it mixes with the droplets and so that the

droplets absorb the pollutants draining away the solvent with the pollutants

and exhausting the cleaned gas.

In a preferred embodiment of the invention, the solvent is water. The or each member may have a generally planar form advantageously in the

shape of a disc although other, for example polygonal shapes, may be used.

In the case of a plurality of members, the members are arranged parallel or

substantially parallel to each other defining passages therebetween through

which the water may in use pass. The dimensions of the gaps may be varied as desired, but is preferably less than 10mm and advantageously

about 3mm. The or each member may be provided with formations in order

to promote the formation of a spray in use. Thus the or each member may

be stepped and/or the surface thereof may be provided with dimples or

other shapes. The means for moving the or each member may comprise an electric motor driving through a belt drive connected to a shaft to which the

or each member is connected operation of the motor results in rotation of

the shaft and through it the or each member. The means for supplying

polluted air (or other gas) may comprise a pipe extending through the or

each member and defining outlets through which polluted air flows out. The

means for supplying water may also comprise a pipe extending through the or each member also defining outlets through which water may flow.

Preferably, the water may be pumped through the pipe by a pump and the

water and air pipes are coaxial along those parts of their lengths through the

member or members. Impellers may be arranged on the periphery of the or each members so that in operation air is drawn therethrough.

In order that the invention may be more clearly understood

embodiments thereof will now be described, by way of example, with reference to the accompanying drawing, in which :-

Figure I is a diagrammatic cross-sectional view of one form of

apparatus according to the invention,

Figure 2a is a partial plan view of a modification of the arrangement

of Figure I,

Figure 2b is a cross-section along line II-II of figure 2a,

Figure 3a is a partial plan view of another modification of the

arrangement of Figure I,

Figure 3b is a cross-section along line Ill-Ill of Figure 3a.

Figure 4 is a diagrammatic end elevational view in cross section of a

further embodiment of the invention,

Figure 5 is a diagrammatic side elevational view in cross-section of

the embodiment of Figure 4,

Figure 6 is a plan view of one of the discs forming part of the

embodiment of figures I and 2, and

Figure 7 is a diagrammatic cross-sectional view of the disc of Figure 6.

Referring to Figure I, the apparatus comprises a housing I defining a

tank in its lower part 2 for holding water. An electrically driven pump 3 is

also disposed in this lower part. This pump 3 is operative to pump water through a pipe 4 to a unit disposed in the upper part of the housing I which

comprises a plurality of disc form members 5 coaxially arranged around the

pipe 4. An air pipe 6 leads through the wall of the housing I and the water in the lower part of the housing through the members 5. That part of the

pipe extending through the members 5 is coaxial with the corresponding part of the water pipe 4.

The unit comprising the disc form members is connected to a

vertically mounted drive shaft 7 mounted in bearings 8. The shaft 7

supports a pulley 9 in which a drive belt 10 is disposed driven, in operation,

by an electric motor II through a further pulley 12 arranged on the output

shaft 13 of the motor II. The disc form members 5 are advantageously

disposed about 3mm apart but this spacing may be varied as required possibly up to 10mm. These members may also be formed with surface

formation to promote the formation of spray from the water supplied to

them. The member may be stepped, for example, or provided with dimples.

Referring to Figure 2a, a partial plan view of modified disc form

member is shown. Figure 2b shows in cross-section of this member along

the line II-II of Figure 2a. This disc comprises two steps 20 and 24 in its

surface. These steps are circular in plan view and aid the formation of spray

in operation. Impeller blades 22 are attached to the periphery of the disc

form member. In operation these blades draw air and water across the

surface of the disc form member. Six such blades are disposed at regular

intervals around the periphery of the member only three being shown as

only half of the member is shown.

Figures 3a and 3b show another modification. Figure 3a shows a

partial plan view and Figure 3b a cross-section along the line Ill-Ill of Figure 3a. There are six discs form members 30 arranged coaxially and parallel

with an inter member spacing of about 3mm. Each member is stepped at

31. This step 31 is circular in plan view. Impeller blades are shown at 32.

In operation polluted air is supplied to the apparatus through pipe 6

and water is pumped through pipe 4 by pump 3. The disc form members are

rotated at high speed by the motor 1 1 through the belt IO and shaft 7. Air

flow through the apparatus is indicated by dotted lines 15 and water flow by full lines 16. Both air and water emerge through outlets in their respective

pipes 6 and 4 and travel through the gaps between adjacent disc form

members to the periphery of the members. Where fitted, the impellers help

to draw the air and water through these gaps. As the water is forced

through these gaps between the rotating disc form members a fine spray of

water droplets is formed. The spray formation is aided by the formations on

the surface of the members. The water droplets absorb the pollutants from

the polluted air which is thoroughly mixed with the water as they pass

through the gaps. Water carrying the pollutants drains back from the peripheral edges of the members to the water tank from which it can be

drained away for appropriate disposal when required. Cleaned air exhausts

through an outlet pipe 17.

Referring to Figures 4 to 1, the apparatus shown in these figures

comprises a housing 41 defining a tank 42 in its lower part for holding

solvent. An electrically driven pump 43 is disposed to pump solvent

(usually water) through inlet pipes 44 to a unit supported in the housing 41 and comprising a plurality of cast aluminium disc form members 45 coaxially

supported on a horizontally arranged hollow axle 46 supported on bearings

47 and 48 at opposite ends respectively thereof. In this example, there are

thirty members 45 although the number may be varied as desired. The

members 45 are respectively disposed in regularly spaced apart vertical planes. This spacing is varied as desired preferably in the range 3 to 10mm.

The axle 46 supports a pulley 49 at one end. This pulley is drivably

connected via a belt 50 to an electric drive motor 51. Two gas inlet ducts

52 and 53 lead into the housing 41 at opposite axial ends thereof and a gas

exhaust duct 53 leads from the housing. A part-semicircular shroud 54 surrounds the members 45. This shroud which may optionally have coolant

flowing through it is spaced away from the members 45. On the upper side

of the members 45 this spacing may be approximately 15cm. In operation

the shroud may serve as a condenser of vaporised solvent. It may also help

to collect fine spray of solvent droplets suspended in the moving gas. A

water outlet pipe 55 leads from the tank 42.

Each of the disc form members 45 has surface formations. Referring

particularly to Figures 6 and 7 and moving from the outer periphery of the

member 45 radially inwards, there is first of all a ring 56 of sixteen equally

spaced fins 57 on a 10° pitch. Adjacent the ring 56 is a ring 58 of equally spaced mixing plates 59. These plates are 1 square cm in size but their

size can be varied as desired. Adjacent the ring 58 is a raised annulus 60

which is operative to slow the flow of gas across the member 45 and increase the swirl of water. A further ring 61 of mixing plates 62 is

disposed adjacent the annulus 60 and a further ring 63 of twelve equally

spaced fins 64 on a 10° pitch adjacent the ring 61.

The operation of the embodiment of figures 4 to 7 is similar to that

of the embodiments already described. Polluted gas enters the apparatus

in the direction of arrows 65 via gas inlet ducts 52 and 53 and flows

through the centre of the members 45. A liquid solvent, usually water

enters the apparatus through inlet pipes 44 and leaves these tubes via holes

arranged along their length. The members 45 are rotated at high speed by

the electric motor 51 driving through the belt 50, pulley 49 and hollow axle

46. The solvent is sprayed radially outwardly through the gaps between

adjacent members 45. The formations 57, 59, 60, 62 and 64 on the

members 45 promote mixing between the polluted gas and solvent as they

pass between the member 45 in the direction of arrows 66. Vaporised

solvent condenses on the inner surface of the shroud 54 and drains down

into the tank 42 from which it may be drained off through the pipe 55. The

shroud also collects fine mist or spray exiting the members 45 which

similarly drains down into the tank 42. Cleaned gas exits through the gas

exhaust duct 53.

It will be appreciated that the above embodiment has been described

by way of example only and that many variations are possible without

departing from the scope of the invention. Although the members are

described as disc form they may be any other suitable shape. Any number of members from one upwards may be used. Step formations or blades on

the members may be varied as required. Other formations whether proud

of or indented into the member surface may be used. A fan may be

associated with the outlet pipe to draw air through the apparatus. Baffles

could be included downstream of the fan to reduce residual moisture

content.

Claims

C AIMS

1. Apparatus for removing gaseous pollutants from gas comprising

means (3,4,44) for supplying a liquid solvent to a unit comprising one or

more members (5,45), means for moving (10,1 ,50,51)the said one or more

members, in order to create spray comprising a multiplicity of droplets from

the solvent supplied and means for supplying polluted air (6,52,53) to the

unit to mix with the droplets of the spray in order to remove pollutants from

the gas, means for removing solvent (2,42) bearing the pollutants from the

unit and means for exhausting gas ( 17,53) from which the pollutants have

been removed.

2. Apparatus as claimed in claim 1 , in which the or each member (5,45)

is of substantially planar form.

3. Apparatus as claimed in claim 1 or 2, in which the or each member

(5,45) is a disc.

4. Apparatus as claimed in claim 1 , 2 or 3, in which the members (45)

are substantially horizontal.

5. Apparatus as claimed in claim 2, 3 or 4, in which the members (5) are

substantially vertical.

6. Apparatus as claimed in any preceding claim, in which the members

(5,45) are arranged parallel or substantially parallel to each other defining

passages therebetween through which solvent may, in use, pass.

7. Apparatus as claimed in any preceding claim, in which there are at

least two members and the gap between the members of the or each pair is less than 10mm.

8. Apparatus as claimed in claim 7, in which the gap between the

members (5,45) of the or each pair is 3mm.

9. Apparatus as claimed in any preceding claim, in which the or each

member (5,45) is provided with formations (20, 21, 22, 30, 31 , 32, 57, 59,

60, 62, 64) to promote the formation of spray.

10. Apparatus as claimed in claim 9, in which the surface of the or each

member (5, 45) is stepped.

11. Apparatus as claimed in claim 9 or 10, in which the surface of the or

each member (5,45) is dimpled.

12. Apparatus as claimed in claim 9, 10 or 11 , in which the surface of

the or each member (5,45) is provided with fins.

13. Apparatus as claimed in any preceding claim, in which, the means for

moving the or each member comprises an electric motor (11 ,51 ) operative to drive a shaft on which the members are supported through a belt.

14. Apparatus as claimed in any preceding claim, in which the means for

supplying polluted air comprises one or more inlet pipes (6,52,53).

15. Apparatus as claimed in any preceding claim, in which the means for

exhausting gas comprises an exhaust pipe (17,53).

16. Apparatus as claimed in any preceding claim, in which the means for

removing solvent comprises a tank (2,42) into which polluted bearing

solvent may drain.

17. A method of removing pollutants from gas comprising the steps of supplying a liquid solvent, producing spray of droplets of solvent, passing

polluted gas through the spray so that it mixes with the droplets and so that

the droplets absorb the pollutants draining away the solvent with the pollutants and exhausting the cleaned gas.