US2603309A - Apparatus for removing dust from gases - Google Patents

Description

APPARATUS FOR REMOVING DUST FROM GASES Filed March 29, 1949 2 SHEETS-SHEET l Marcel Ehl instr ATTORNEY E. MERCER Erm. S 2,603,309

APPARATUS FOR REMOVING DUST FROM GASES Filed March 29, 1949 2sHEETs-sHEET2 Patented July 15, 1952 APPARATUS FOR REMovlNG DUST FROM GASES Ernest Mercier and Marcel Ehlinger,` Paris, France, assignors, by mesne assignments, to Moore, Inc., Atlanta, Ga., a corporation of Georgia Application March 29, 1949, Serial No. 84,144

In France April 3, 1948 V 15 Claims. 1

The present invention has for its object apparatus for removing dust from gases which consists in leading the gas into the apparatus at high speed as a thin layer (about 1 cm. in thickness or even less) and leading it out as a thin layer of substantially the same thickness after a change of direction of about 180, or at least a very substantial and abrupt change of direction, has been imposed upon the flow of the gas, the mean radius of curvature of the bend being quite Smalli. e. likewise of the order of one centimetre or even less, whereby considerable momentums' are set up which tend to hurl the dustv particles conveyed towards the outside of the bend whereby the desired dust removal is Secured.

The invention is also concerned with apparatus by means of which gases resulting from the combustion of coal can be purified by removing therefrom the 'ash and clnker therein, which apparatus is capable notably of dealing with gases at high temperatures and with gases under pressure. y

Apparatus of this kind should be composed of metal parts that are simple in design, not liable to be deformed by the action of heat and a slight deformation of which will not be detrimental to their proper operation. In addition,v the dimensions of the apparatus should be small so that no large-sizev pressure-resisting casings have to be used where the fseparation is to be effected from gases under pressure. y

Moreover, the units composing the apparatus should be simple and it should be possible to connectthem in series in order to enhance the cleaning elect or infparallel in order to increase the output.

The unit' of the apparatus according to the invention comprises .a double channel delimited by plane or substantially plane metal sheets, generally three of themfcomposing an elemental section of the unit; arranged substantially parallel to and at very `small distances from one another. The gas to -be,.purified flows rstly throughV the channeli comprised between one of the outer vsheets and the central one, then in the reverse direction through the channel comprised betweensaid central sheet and the other outer sheet. As the gas passes from the first channel into the second one its direction of ow is deflected through an angle of18() over a bend of very small radius, whereby the removal ofathe dust is performed by the action of the centrifugal force upon the particles. s

Of course, theA passage leading from the first (Cl. 18S-79) channel into the second one should be so dimensioned in dependency on the character and size of the particles to beeliminated that a satisfactory operation' of the apparatus is secured.

A first solution of this problem consists in providing a passage forming'the bend continuous with the leading in channel, this passage being delimited by a wall that in a particular embodiment may be an extension of either or both of the outer walls, said wall being provided with one vor several slits suitably located to facilitate. the discharge of the particles to be removed.

A further solutionconsists inhaving Ythejthree parallel sheet metal walls with their edges substantially in a plane transverse to the planes of the sheets, the channels therebetween opening freely into a chamber in which the dust is co1-` lected.

A third solution consists in inwardly oisetting from the transverse plane thev edge of the inner or central wall with respect to the edges of the outer ones in an arrangement which otherwise remains the same as vthe Vsecond solution. A

Units similar to the ones justgdescribed may be grouped in series, also by pairs in order to lessen head losses between two successive units.

In another embodiment the lunits may also be arranged radially about a common axis 'of rotation within a slotted cylindrical coaxial -barrel connecting them with one another, the median plane of each unit going through said aXis of rotation. The rotor comprising the barrel and the units may be rotated at high speed, the design' of the inner 'channels being such that the gases to be purified are taken into the apparatus` through the one end plate'of the barrel and out of it through the opposite end plate whilea dust collector surrounds the rotor.

Of course, where the gas to be purified is under pressure, the unitsy should be arrangedwithina pressure-resisting casing In this case special steps should be taken'to avoid the condition that removal of the accumulated dust is attended with arv loss of4 the lgas under pressure.- Such removal may be effected',y according to lthe invention, by spraying water into the apparatus in such a manner that a sludge is formed therewith that is discharged to the outsidezofthe pressure resisting casing through a pipe'the diameter and length of which are so chosen that continuous removal is secured without any risk of. clogging and at reasonably low costs.

Several embodimentsof the present invention are `illustrated by wayv of Aexample in the Vappended drawing.'

Figures 1, 2, 3 respectively show the three aforementioned solutions or types of dust-removing units.

Figure 4 is a diagrammatical longitudinal View, and Figure 5 a cross-sectional view taken on line V-V in Fig. 4, which show a dust-removing apparatus comprising a single group formed of a plurality of units.

Figure 6 illustrates a dust-removing apparatus composed of two groups of units in series in opposed relation.

Figure 7 shows a dust-removing apparatus comprising three groups of units in series in a different arrangement.

- Figures 8 and 9 diagrammatically show a rotary dust-removing apparatus in lonigtudinal and cross-sectional views respectively.

Figure 1U diagrammatically shows a dust-V removing apparatus for removing dust from gases under pressure, together with its hydraulic dustdischarging system'.

In the dust-removing unit shown in Fig. l, the dust-laden gas is led in through channel I and out through channel 2 as a thin layer. At 3 a bend is formed in which the particles are urged outwardly by the centrifugal force and tend to escape through a slit 4 into a chamber outside the unit. The channels and the bend are defined by walls made of thin sheet metal. Experience has shown that if suitably dimensioned and operated withsuitable gas flow speeds such a unit possesses a high separating capacity which, of course, .is dependent on the character and size of the dust particles. The radius of curvature Vof the passage forming the bend is of the order of a. few millimetres or of one centimetre.

According to Fig. 2 the wall dening the bend is dispensed with, and so it is in Fig. 3 in which the side walls extend beyond the middle one.

These elemental units forming U-shaped channels are juxtaposed in any desired number to deal with any desired gas flow.

FigureV 4 shows a dust-removing apparatus composed of similar units contained in a casing or chest and so arranged that the gas flows in from conduit A5 Yand out to conduit 6 and is deflected through the unit as shown by the arrow. For that purpose a barrier partition or end wall 9 is provided which closes the remote ends of the channels through which the gas to be puried isvled in from conduit 5 and prevents it from flowing out directly through conduit B, said partition 9 being apertured to provide a free exit at this end of the channels through which the purified gas after sharp reversal of its flow is led out to conduit 6. The entering gas is prevented from entering these reverse now channels by barrier walls 9 which in the embodiment of Figs. 4. 5, 6 and 7 are inclined to the direction of the entering gas, the Walls between the channels being of generally triangular shape.

The barrier walls 9, 9 provide means cooperating with the walls of the units and with the casing to conne the gas to ilow from the inlet opening in succession through the channels with reversal of the flow about the central walls or partitions of the units. The casing, moreover, provides means cooperating with the walls of the units to insure such gas flow and to effect discharge of the materials suspended in the gas under the centrifugal force developed by such reversal. The dust particles settle in a hopper 1 which, if desired, may contain baflles bywhich the dust already deposited is retained and prevented from being'whirled up back into the gas flow. A handor power-actuated rake 8 serves to clean the narrower portions of the channels.

Experience has shown that by providing a fan adapted to sucka small fraction of the gas from the hopper the efficiency ofrthe apparatus is increased. This fan 40 forces the more or less purified gas thus tapped from the hopper again into the intake 5 of the apparatus.

The dust remover shown in Fig. 6 is composed of two units similar to the one shown in Fig. 4, with the peculiarity that they are arranged symmetrically and that their side walls 9 are contigucus. The barrier partitions 9 retain the gases from flowing directly from the intake 5 to the outlet 5. ,On the other hand they allow them to rflow from hopper IU into hopper II.

As shown in Fig. '7, the dust remover comprises three units. It will be appreciated that the dustremoving effect is improved according as the gas passes through alarger number of units, which is confirmed by experience. The units may have unequal sections so that the flows therethrough are unequal. They may be arranged one after the other in a straight line or otherwise, e. g. in

a helix.

Figs. 8 and 9 illustrate a dust remover which likewise comprises units providing channels I2, I3 defined by partitions 3|, 32, 33 arranged in a rotor driven at high speed. The units are formed so that channels I2, I3 are radial. Four of these units are shown in the drawing, yet a less number or a considerably larger number of them may be used if desired. The gas is taken in at the inlet I4 and out at the outlet I5 and its paths of flow are indicated by the arrows. In the outer portions I6 of the channels ow reversing passages are formed in which the centrifugal effect of the rotation adds to the removing action of the unit which is secured by sharp reversal of direction about the edge of partition 3I. The particles settle in the annularV chamber provided by casing 35 and fall into hopper I'I connected to the bottom of this casing. The casing 35 and the walls of the rotor which provide the channels I2, I3 cooperate to confine the gas to flow in succession through these channels and to be reversed in passing from one to the other so that the combined effects of reversal and of centrifugal force due to the rotation insure the separation of the particles from the gas.

The rotor is driven by means of the shaft I8 that carries a pulley I9 and is mounted in bearings 20. Stuffing boxes 2|, 22 or similar devices are provided to prevent leakage between the separation chamber and the gas inlet and outlet and at the point of passage of the shaft through the inlet conduit I 4. The rotor may be keyed on the same shaft as the fan or blower (not shown) which produces the circulationI of the gas. If desired a plurality of rotors may be arranged in series upon the shaft I8 in th'e direction of the gas flow in order to improve the separating effect or a plurality of rotors may be arranged in parallel with respect to the gas flow in order to increase the output. Rakes may be provided to clean the narrower portions of the channels. The arrangement may be such that the gas flows through the rotor either in a generally ascending or a descending or in a horizontal direction.

If the gas to be puried is under pressure, the apparatus is housed in a pressure resisting vessel, which is easily conceivable with the rotary arrangement shown in Fig. l8' if the inlet conduit I4, the casing 35, the hopper I1 and the outlet conduit therefrom are constructed to be pressure resisting. Fig. illustratesa dust remover composed of stationary units similar to those of Figs. 4, 5 and 6 enclosed in a cylindrical pressure-resisting casing or pressure vessel. This embodiment is Icomposed by way of example of four units 23 arranged symmetrically by pairs. The dust laden gas under pressure enters through inlet 5 and after passing in series through the units 23 is discharged under Ypressure at outlet 6. The dust settles in the hoppers 24. Partitions 25 separate the hoppers and units in the same manner as do partitions 9 in Fig. 6.

Such a dust remover may be constructed to operate under considerable pressure, i.' e. 100 kgs/sq. cm. or more, and may conne gases at a very high temperature. It maybe arranged within a gasor water-jacketed pressure vessel cooled by a suitbale gas or by water circulated through the jacket. l f

If desired the action ofl such dust removers, whether they be stationary or rotary, may be improved by ionization of the dust particles in the-conventional manner.

The dust may be discharged from the hoppers of the pressure vessel of Fig. l0 either through a conventional lock chamber or with the aid of the device about to be described.

In Fig. 10, the dust falls from each hopper 24 through pipes 26 into which respectively water is forced by a pump 21 through pipe 31 and branches 38, 39. The dust mixes with the water and the resulting quite uid sludge is collected in a tank 28 which is subjected through pipes 26 to the pressure prevailing in the dust remover and is constructed to withstand this. pressure. Owing to this pressure, the sludge may be continuously discharged to the atmosphere through a pipe 29. The sectional area of the pipel 29, however, is so chosen that the rate of flow therethrough is not so great as to cause a reduction in the pressure Within the-pressure vessel and in the tank 28 and on the other hand is suicient for continuous discharge of the sludge as it is formed without clogging of the pipe. YWithout requiring an excessive length of the pipe-29 the sectional area of the pipe may be su'iciently restricted to limit the ilow therethrough to maintain the pressure without developing velocities in the pipe 29 which would cause excessive wear. The pressure drop necessary for dischargingA the sludge from the tank under high'pressure to the atmosphere is accomplished, however, by the restriction of the area for ow through the pipe 29 and the water thus discharged from the tank is replaced by the pump 29 which is capable lof delivering this water against the pressure within the tank 29.` Suitable control means controlling the delivery of the water to the tank may be used for keeping the water in thetank 2B substantially at a given level therein. Experience has shown that such a devicefor removal of the dust separated within a pressure vessel is quite suitable for the purposes of the invention.

The invention is applicable to all kinds of gases and dust particles. It is also applicable to the removal of liquid particles in suspension in gases or vapours.

The flow through the units may be horizontal, vertical or oblique in the different embodiments provided the hoppers are suitably arranged in relation to the passages between the channels of the units so as to collect the material separated from the gas in these passages due Ato reversal .of the flow therein. Y

1. Apparatus for separating from a gas material suspended therein which' comprises a casing providing a separating chamber and having a gas inlet opening at one side of said chamber and a gas outlet opening at the opposite side of said chamber, at least one particle removal unit supported in said chamber providing a pair of narrow generally parallel channels dened by a partition wall and twov outer walls generally parallel thereto and spaced therefrom at opposite sides thereof, means conducting the gas with said material suspended therein through said inlet opening into 4said chamber for flow therethrough toward said outletopening, said walls vof said unit beingdisposed parallel to the direction of ow from said inlet opening'toward said outlet opening,means cooperating with said walls of said unit and with said casing for conning said gas to flow from said inlet opening through the channel between said partition wall and one of said outer walls of said unit and then about an edge of said partition wall to flow reversely through the other channel between said partition wall'and the other outer Wall of said unit, means cooperating with said walls of said unit and with said casing for withdrawing through said outlet opening the gas from said other channel of said unit, means cooperating with said partition wall and said outer walls of said unit for effecting discharge of the material suspended therein from said gas under the centrifugal force of reversal of its flow in passing from the rst channel to said other channel, and means for collecting said material discharged and separated from said gas for removal from said casing. l

2. Apparatus for separating from a gas material suspended therein which comprises a casing providing a separating chamber' and having a gas inlet opening at one side of said chamber and a gas outlet opening at thefopposite side of said chamber, at least one particle removal unit supported in saidfchamber' providing a pair of narrow generally parallel channels defined by a partition wall and two outer walls generally parallel thereto and spaced therefrom at opposite sides thereof, means conducting theV gas with said material suspended therein through said inlet opening into said'y chamber for now therethrough toward said outlet therefrom, said walls of saidvunit being disposed parallel to the direction of flow from said inlei-l opening toward said outlet opening, a barrier wall spanning across at least one of said channels kand cooperating with said partition and outerwalls of said unit and with said casing to confine the gas from said inlet opening to flow lthrough one of said channels and to reverse its ow about an edge of said partition wall and to iiow reversely through the other channel toward said outlet from said chamber, said barrier Wallpreventing flow of the gas between said channels aboutsaid partition wall diverging fromfsaid flow of said gas along said iirst channel and then reversely along said other channel, means cooperating with said partition wall and said outer walls of said unit for effecting discharge of the material suspended therein from said gas as reversal of its iow is effected in passing from said rst channel to said other channel, and means for collecting said dischargedA initially suspended material for removal from said casing.

3. Apparatus for separating from a gas material suspended therein whichcomprises a casing providing a separating chamber and having' a gas inlet opening at one side vof said chamber and a gas outlet opening at 'the opposite side of said chamber, at least one particle removal unit supported in said chamber'providing a pair of narrow generally parallel channels dened by a partition wall and two outer walls generally parallel thereto and spaced therefrom at opposite sides thereof, means conducting the gas with said material suspended therein through said inlet opening into said chamber for flow therethrough toward said outlet therefrom, said walls of said unit being disposed parallel to the direction oi flow fromvsaid inlet opening toward said outlet opening, -a barrier wall extending transversely of said partition wall and cooperating therewith and with one of said outer Walls of said unit and with said casing to corinne said gas from said inlet opening to flow vdirectly into one of said channels to flow therealong and to prevent flow of said gas directly into said other channel, a barrier Wall extending transversely of said partition wall and cooperating therewith and with the other outer wall of said unit to close the end of said first channel disposed toward said casing outlet, said walls and said casing cooperating to coniine the gas to ow along said first channel and to be reversed about an edge of said partition wall and then to ow along said other channel toward said outlet while being prevented from fiowing from said other channel back into said first channel, and means cooperating with said partition Wall and said outer walls and said casing adjacent said edge of said partition wall for collecting material initially suspended in said gas and discharged therefrom as reversal of its flow is effected about said edge of said partition wall.

4. Apparatus for separating from a gas material suspended therein which comprises a casing providing a separating chamber and having a gas inlet opening at one side of said chamber and a gas outlet opening at the opposite side of said chamber, a plurality of generally parallel partition walls supported in said chamber in spaced relation to each other,means for conducting the gas with said material suspended therein through said inlet opening into said chamber for flow therethrough toward said outlet opening, said partition walls being disposed parallel to the direction of flow from said inlet opening toward said outlet opening, barrier walls disposed with respect to said partition walls toward said inlet and extending transversely of said partition walls across the alternate channels therebetween to prevent entrance oi said gas into said barriered channels, said partition walls cooperating with said casing and said barrier walls to coniine said gas to flow into the other unbarriered channels between said partition walls and to flow in parallel paths therealong, means for conveying said gas from said outlet opening of said casing, barrier walls extending transversely of said partition walls across said channels into which said gas flows at the ends thereof disposed with respect to the gas flow toward said conveying means While leaving open at the ends thereof disposed toward said conveying means said channels barriered adjacent said gas inlet, said casing cooperating with said partition walls and said barrier walls to provide passages communicating between adjacent channels to produce flow of said gas along the channels into which said gas flows from said inlet and thereafter flow of said gas along said alternate channels to be discharged therefrom to said conveying means, said passages being formed adjacent respective edges of the partition walls separating the channels in which said gas ows in opposite directions for effecting sharp reversal of said flow about said edges and separation by centrifugal force in said passages from said gas of said material suspended therein, and means cooperating with said casing and said partition walls and said barrier walls for collecting the material initially suspended in said gas and separated therefrom in said passages.

5. Apparatus for separating from a gas material suspended therein asfdeflned in claim 4 in which said partition walls are arranged in parallel planes vand are of generally right angle triangular shape in said planes with the hypothenuse edges thereof extending at an inclination to the flow of the gas entering said casing and with the other edges of said triangles respectively parallel to and at right angles to said entering flow, said transverse barrier walls which are disposed toWard one of said openings of said casing extending along said hypothenuse edges of said partition Walls, said barrier walls disposed t0- ward the other opening of said casing extending along said edges of said partition walls which are at right angles to said entering flow of said gas,rsaid casing cooperating with said partition walls and said barrier walls to form said passagescommunicating between adjacent channels adjacent the respective edges of said partition walls which extend parallel to the entering flow of said gas into said chamber, whereby said gases entering said chamber are ccnned to turn and to flow through alternate channels generally at right angles to said entering now and then to turn sharply about said edges which extend parallel to said entering iiow and thereafter to ow reversely through said other channels and again to turn generally at right angles to the ow in said other channels toward said outlet opening and said means for conveying' said gas from said casing. j

6. Apparatus for separating from a gas material suspended" therein as defined in claim 1 in which said casing is constructed as a pressure vessel capable of confining gas at substantial pressure therein, said unit being supported within said pressure vessel, said means for collecting said discharged and separated material for removal from said casing being connected to means adapted to effect said removal while cooperating with said casing to confine said gas under pressure within said pressure vessel.

'1. Apparatus for separating from a gas material suspended therein as defined in claim 6, said means for eecting removal of said discharged separated material comprising a tank connected to said collecting means and to said pressure vessel to receive the discharged separated material while subjected to said pressure, means for delivering liquid under pressure to said tank for mixture therein with said separated material, and means for discharging said mixture of said liquid and said separated material continuously from said tank while maintaining said pressure of said gas within said tank and said pressure vessel.

8. Apparatus for separating from a'gas material suspended therein as dened in claim 2 which comprises a plurality of said units arranged within said casing for flow of said gas in series therethrough, said partition and outer walls in each unit having generally parallel edges inclined with respect to the direction of gas ow through said unit, said barrier wallsI being inclined along said edges, said edges in adjacent units being inclined in the same direction with respect to the direction of the gas flow through said casing.

9. Apparatus for separating from a gas material suspended therein as defined in claim 2 which comprises a plurality of .said units arranged within said casing for flow f said gas in series therethrough, said partition and outer walls in each unit having generally parallel edges inclined with respect to the direction of gas iiow through said unit, said barrier walls being inclined along said edges, said edges in adjacent units being inclined in opposite directions with respect to the direction of the gas iiow through said casing.

10. Apparatus for separating from a gas material suspended therein which comprises a casing providing a separating chamber, a member rotatable within said chamber constructed to provide a passage for ow of gas therethrough from an inlet opening thereof disposed generally centrally with respect to the axis of rotation to an outlet opening thereof disposed generally centrally with respect to said axis of rotation, a particle removal unit carried by said rotatable member and cooperating therewith to conne said gas to ow therethrough from said inlet to said outlet opening of said member, said particle removal unit; being constructed with a generally radially extending partition wall between two outer walls generally parallel to said partition Wall and disposed at opposite sides thereof in spaced relation thereto to provide a pair of narrow channels extending generally radially with respect to said axis of rotation, said walls being formed in relation to each other and to said rotatable member to provide a flow reversing passage disposed radially outwardly of and providing communication between said two channels and communicating outwardly with said chamber, said partition and outer walls cooperating With said rotatable member and with said casing to confine said gas to flow from said inlet opening into one of said channels and to iiow radially outwardly in said channel and to iiow through said outwardly disposed iiow reversing passage and radially inwardly in said other channel to said outlet opening of said rotatable member, means for rotating said rotatable member to produce the action of centrifugal force on the material suspended in said gas to cooperate with the centrifugal force produced by f reversal of said gas ilow in said outwardly disposed fiow reversing passage for effecting separation of said suspended material from said gas and discharge thereof outwardly into said chamber, and means cooperating with said 10 chamber for collecting and removing said material separated from said gas.

11. Apparatus for separating from a gas material suspended therein as deiined in claim 10 which comprises a plurality of said particle removal units carried by said rotatable member and disposed symmetrically about said axis of rotation.

12. Apparatus for separating from a gas material suspended therein as dened in claim 10 in which saidV outlet opening of said member is displaced along the axis of rotation from said inlet opening, whereby the gas ows from said inlet opening generally along said axis of rotation to said outlet opening.

13. Apparatus for separating from a gas material suspended therein as defined in claim 10 in which said partition wall of said unit is connected by a barrier wall to a Wall of said rotatable member to separate the gas flowing from said inlet opening into said channel to flow radially outwardly therein from the gas flowing radially inwardly in said other channel to said outlet opening.

14. Apparatus for separating from a gas material suspended therein as defined in claim 1 in which said particle removal unit is provided with a member supported for reciprocating movement thereof in the direction parallel to said partition and said Walls of said unit and adjacent said edge of said partition wall about which said gas iiows into said other channel, said member being provided with fingers respectively extending into said channels for cleaning said channels of particles deposited on said partition wall and said two outer Walls of said unit.

15` Apparatus for separating from a gas material suspended therein as defined in claim 1 which comprises means for withdrawing from said chamber a portion of the gas adjacent said edge of said partition wall about which the ow of said gas is reversed and for delivering said withdrawn portion to the casing adjacent the inlet opening into said chamber.

ERNEST MERCIER. MARCEL EHLINGER.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,267,297 West May 21, 1918 2,199,015 Toensfeldt Apr. 30, 1940 2,216,664 Fremd Oct. 1, 1940 FOREIGN PATENTS Number Country Date 554,289 Great Britain June 28, 1943

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