US2667942A

US2667942A - Electrified, centrifugal gas cleaning device

Info

Publication number: US2667942A
Application number: US255168A
Authority: US
Inventors: Harry A Wintermute
Original assignee: Research Corp
Current assignee: Research Corp
Priority date: 1951-11-07
Filing date: 1951-11-07
Publication date: 1954-02-02
Anticipated expiration: 1971-02-02

Description

1954 H. A. WINTERMUTE v 2,667,942

ELECTRIFIED, CENTRIFUGAL GAS CLEANING Davies: Filed Nov. 7, 1951 4 Sheets-Sheet 1 INVENTOR I Harry A Vl z nigrmui BY 1M9 ATTORNEYS Feb 1954 H. A. WINTERMUTE 2,667,942.

ELECTRIFIED, CENTRIFUGAL GAS CLEANING DEVICE ,5 BY JMQ-M- ATTORNEYS Feb. 2, 1954 H. A. WENTERMUTE ELECTRIFIED, CENTRIFUGAL GAS CLEANING DEVICE 4 Shee'tsfSheet 5 Filed Nov. 7, 1951 NVENTOR ZermuZZ l/arg A ATTORNEYS Febr 2, 1954 H. A. WINTERMUTE v ELECTRIFIED. CENTRIFUGAL GAS CLEANING DEVICE Filed Nov. 7; 1951 4 Sheets-Sheet 4 ATTORNEYS Joint therebetween may be tack welded. An L-shaped bracket |8 formed of narrow strip of metal, is secured to the tubes I and I4 by screws l9 and 20 to provide proper centering of the tubes and to give support to the assembly. A plurality, for example three, of these brackets may be spaced about the periphery of the tube assembly for added strength.

A conical skirt member 2| is welded to the r 7 outside of the discharge tube I4 and this skirt member flares outwardly toward the discharge end of tube I0. Between the outer edge of the skirt member 2| and the discharge end of tube I0 is provided a restricted annular orifice 22.

Fitted within the tube H] is a sleeve 23 that is removably secured in the tube by a. screw 24. The sleeve carries a pair of identical swirling vane sets or assemblies 25 and 26 longitudinally spaced in the sleeve. These vane sets may be fabricated as castings and each-has a ring portion 21 carrying generally radially extending vanes 28 that are welded to the sleeve 23. The vanes are inclined to the axis of the gas cleaner to impart a whirling or helical motion to gas that passes between the vanes. Both sets of vanes are inclined in the same direction. A flange 29 is fastened to the interior of ring 27 by bolts 39 and the flange has a central opening 3|.

Extending longitudinally through the center of the tube assembly is .a discharge electrode support rod 32 that is carried in

fixed frame members

33 and 34, as will be explained more fully hereinafter. The rod is threaded at the ends Where it passes through the frame members and is retained therein by

nuts

35 and 36. A sleeve 31 is slidingly fitted on the rod 32 and this sleeve has a plurality of identical discshaped discharge electrodes 38 to 42 supported thereon. The discharge electrodes are spaced apart by spacer sleeves 43 to 41. Spacer sleeve 43 and support sleeve 37 are positioned on the rod by a drift pin 43 that passes through matching holes in the rod and sleeves. The end 49 of support sleeve 31 is threaded externally and a nut 50 is screwed thereon for the purpose of retaining the discharge electrodes in position.

One of the discharge electrodes 39 is shown in enlarged detail in Fig. 3. The periphery of the disc is serrated to provide a plurality of discharge points The gas cleaning unit shown in Figs. 1 to 3 is preferably fabricated entirely of structural metal such as steel, cast iron, or the like.

In operation, gas to be cleaned, for example boiler flue gases carrying suspended fly ash, is passed through the tube assembly from left to right as seen in Fig. 1 under a pressure differential existing between the inlet opening I of tube 0 and the outlet opening N5 of discharge tube I4. The unit is energized by impressing a high electrical potential between the discharge electrode assembly and the tubular conduit I0. Sufficient potential is applied to cause the discharge electrodes 38 to 42 to emit corona discharge.

Discharge electrode 38, at the gas inlet end of the unit, serves as a baiile to direct the flow of gas between the vanes 28 of the first vane set 25 and to prevent substantial flow of gas through the opening 3|, which opening is provided to space the flange 29 from the sleeve 34 sufficiently to preclude spark over and short circuit between these members. As the gas passes through the corona discharge emitted from the electrode 38,

the suspended material is electrically charged with a sign the same as the sign of the discharge electrode. The electric field existing between the discharge electrode structure and the tube l0 tends to move the charged particles towards the tube In.

As the gas passes between the vanes of the first vane set 25, a helical motion is imparted thereto. The centrifugal force thereby produced tends to throw the suspended particles towards the inner wall of tube Hi. Centrifugal force thus aids the electrical forces tending to move the suspended material toward the outside of the cleaning zone.

As the gas passes through the zone between vane sets 25 and 26, it continues to whirl but at a diminishing rate. In this zone, the gas is subjected to further discharge and electrical precipitation conditions and the suspended material becomes more concentrated in the outer reaches of the zone.

Discharge electrodes

39 and 40 act as baflies to maintain annular fiow of gas, to direct the gas stream through the second vane set 26, and to substantially prevent flow of gas through the opening 3| of the second vane set.

The gas next passes through the second vane set 26 wherein additional helical motion is imparted thereto. The whirling annular stream then flows past the discharge electrodes 4| and 42 and is there subjected to further electrical precipitation conditions. After passing the last discharge electrode 42, the suspended material is concentrated in a very thin layer adjacent the wall of tube l0. Momentum carries a thin layer of gas containing most of the suspended material through the opening 22. Owing to the restricted nature of opening 22, most of the gas stream is turned inwardly around the electrode 42 to fiow out of the discharge tube l4 as clean gas. This turning movement throws out of the exhaust gases a final though small increment of suspended material. Substantial separation of suspended material is thus'efiected by conjoint electrical precipitation and centrifugal action.

It will be seen that the unit thus far described is a two stage unit and that the vane set 26 and discharge electrodes 4| and 42 comprise a second stage. Although less eflicient, a single stage unit can be made by omitting the second stage elements, shortening the tube 0, and moving the discharge tube l4 into a relationship with the discharge electrode 40 similar to the rela- Zionship it has in Fig. 1 with respect to electrode From an inspection of Fig. 1 it is seen that the unit is readily disassembled. The drift pin 48 is removed and the sleeves and discharge electrodes are moved forwardly on the rod 32. The flange ring 29 of the vane set 25 is removed after removing bolts 30. The rod 32 is loosened from the

frame members

33 and 34 by obvious manipulation of

nuts

35 and 36. It will be observed that the outside diameter of the electrode discs 38 to 42 is less than the inside diameter of vane supporting rings 21 so that the former may be withdrawn through the latter. Flange ring 3| of vane set 26 is also detached from the vane set. Thereafter, the entire discharge electrode assembly is withdrawn. The vane assembly is then readily withdrawn after removal of screw 24. Reassembly of the unit is performed by reversing the order of the steps of disassembly.

A plurality of gas cleaning units such as have been described hereinbefore are employed in a gas cleaning apparatus as shown in Figs. 4 and 5. Referring to these figures, 52' represents a casing having a gas inlet opening 53 and a gas outlet opening 54. Gasto be cleaned flows through the apparatus in the direction of the arrows of Fig. 4. The diaphragm plates are shown at It and I1 and these plates define a dust compartment 55 communicating with a dust hopper 55 at the bottom of the casing. The dust hopper has an outlet 51-. This arrangement of bafiie plates causes the main stream of gas to divide and flow through the severalgas c1eaning units 58 supported by the plates 13 and H in the manner described hereinbefore. After cleaning, the gas flows to the outlet 54'.

A small amount of gas together with the dust separated in each unit passes from the annular dust skimming openings. 22 of the units into the dust chamber 55. The dust falls into the hopper 56 from which it is removed through the outlet '5. The dust chamber and hopper may be vented, for example, through the discharge opening 51, if necessary to control back pressure on the annular openings 22 of the gas cleaning units 58.

As has been described, the high tension electrode assembly rods 32 are supported by'frame

members

33 and 34. As. can best be seen in Fig. 5, each horizontal frame member 33 supports the front ends of two electrode rods 32. The horizontal frame members 33 are attached to vertical frame members 59 that are suspended from a yoke bar 60 carried by a cross bar 6| supported by an insulator 62 on the roof of housing 52. Lateral braces 63 and 64 lend added rigidity to the frame structure. The rear ends of the electrode rods 32 are supported in a similar frame structure.

It will be seen that the vertical frame members pass through openings. 65 in the roof of the housing and these openings are covered by insulating bushings E55 that form gas seals between the vertical frame members 59 and the housing.

lhe complementary electrodes of the cleaning units are energized conventionally as by grounding the casing 52' and'connecting the high tension side of a grounded source of current (not shown) to the high tension electrode system through a cable 61.

Referring to Fig. 6, another form of gas cleaning unit in accordance with the invention. is shown. This unit differs from that shown in Figs. 1 to 3 primarily in the manner in which the high tension electrodes are supported. Because of the similarity of the units, parts in the unit of Fig. 6 that correspond to parts in the unit of Figs. 1 to 3 are designated by the same reference numerals with prime characters.

In Fig. 6 the unit includes the tube It", providing a centrifugal and electrical precipitation zone, the main discharge tube I4, and the conical skirt 25', forming with the tube it. an annular skimming orifice 22.

It is seen that the high tension electrode rod 32' is supported at one end only in the frame member 35 and is locked therein .by' nuts 35' and 35. The rod terminates at the unsupported .end 58 in the space between the vane sets 25 andZB. Since there is no electrode disc corresponding to the disc 33 of Fig. 1, the opening in the. ring 21 of the vane set 25 is closed by a flanged plate 69 secured in the opening by bolts 30", this to preclude flow of gas through the vopening.

It is contemplated that the plate 69. can be re-: placed by a flanged ring 'such'as thering 29., the rod lengthenedto extend tothe' left through the ring opening, anda' discharge elect-rode positioned on the rod in front" of the opening to correspond to the disc 38 of Fig. 1.

Operation of the unit-of-Fig. 6 is essentially the same as the 'hereinbefore described operation of the unit of Fig. 1. Also themethod of assembly and disassembly of the unit will be apparent:

A gas cleaning apparatus utilizing units of the type shown in Fig. 6' is illustrated in Fig. '7. Primed reference numerals in Fig. 7' designate parts corresponding to partsin Fi'gsl'd'ar'id 5-having the same reference numerals.

Referring to Fig. '1, the casing 52 hasia pair'of partitions I3 and I1 defining a dust chamber 55' communicating with a hopper 56. Thepartitions support a plurality of'gas cleaningunits' 58 of the kind shown in Fig. 6; Electrode rods'32' are secured in horizontal frame members Mthat are carried by the vertical frame members 59".

A washing device is included in the apparatus of Fig. 7. A header pipe 10 runsparallel to each vertical row of cleaning units 58' on'the'upstream side of the units. Nozzles ll direct a spray washing liquid into the cleaning units; The'washing operation may be performed'as desired by opening and closing a main valve 12. Typically the spray nozzles H are operated continuously to pro vide continuous films of flushing liquid along the inner surfaces of the gas cleaning units. The liquid films trap the particles removed from the gas to provide high efiiciency of "collection. When such a flushing operation is performed, very little gas is required for scavenging purposes as the flushing liquid performs this operation.

The gas cleaning apparatus of Fig. '7 operates in the same way as the apparatus. ofFigs; 4 and 5 as described hereinbefore.

Still another form of gas cleaning unit'of the invention is shown in Fig. 8. Inlthis form, the electrode rod 32" is supported at'the'front end only; otherwise, the unit per se' is substantially identical to the unit of Figs; 1 to' 3. It has the tubular elements 10" and I4" supported bythe diaphragm plates 13" and IT, together with the vane sets 25" and25" and the high tension elem trode assembly including the serrateddisdelec' trodes 38" to 42".

Fig. 9 shows a plurality of such units embodied in a gas cleaning apparatus similar to the ap'- paratus of Figs. 4 and 5. The casing 52" has partitions l3 and I1" defining with the'casing a dust chamber 55" communicating". with the hopper 56' at the bottom. The partitions-l3" and I1 support the cleaning units 58".

Rods 32" are anchored in horizontal frame members 33 that are mounted on vertical frame members 59". The frame mernbersfie" rest" on insulators H3 at the bottom and pass through insulating bushings 66" at'the top ofthe apparatus.

The operation of the apparatus of Fig. 9 will be obvious from the description given hereinbefore of operation of the apparatus ofv Figs. 4 and5.

Althoughthe skirt member. 21 of Fig. 1 that provides a restricted skimming. orifices 22- is desirable, the skirt may be eliminated under certain conditions as when the annular-space between tubes H3 and 1 5 is sufficiently small to eliminate the need for the skirt-member.

From the foregoing description .it will beseen that the present invention provides a gas cleaning device and apparatus combining in a unique way principles, of centrifugal separation and electrical precipitation. In the treating units shown and described herein; the" fiGWpfgas 7 through the units is so directed as to insure maximum efiiciency of centrifugal and electrical action. Moreover, the units are easily fabricated, assembled and disassembled. The invention provides a gas cleaning device that satisfies the aims and objects of the invention.

In the light of this disclosure, one skilled in the art will perceive that a variety of engineering and design changes can be made in the physical form of the apparatus without departing from the spirit of the invention.

Similar subject matter is disclosed in my continuation-in-part application Serial No, 285,094 filed April 30, 1952.

I claim:

1. An electrified, centrifugal gas cleaning device comprising a tubular conduit member providing a gas swirling and electrifying chamber, said conduit member having an open gas inlet end and an open gas outlet end, a discharge tube having an open gas inlet end and an open gas outlet end and having an outside diameter smaller than the inside diameter of said tubular conduit member, said discharge tube projecting into the outlet end of said tubular conduit memher and being positioned coaxiallyewith respect to the latter, a skirt member carried on the outside of said discharge tube and flaring outwardly towards the outlet end of said tubular conduit member and providing therewith a restricted annular skimming orifice, a first set of annularly arranged swirling vanes positioned against the inner wall of said tubular conduit member near the inlet end thereof, a second set of annularly arranged swirling vanes positioned against the inner Wall of said tubular conduit member intermediate said first set of vanes and the inlet end of said discharge tube, a first disc-like discharge electrode insulatedly supported in the space between said first and second sets of swirling vanes, and a second disc-like discharge electrode insulatedly supported in the space between said second set of swirling vanes and the inlet end of said discharge tube, said discharge electrodes being of substantial diameter and having discharge points spaced from the inner wall of said tubular conduit member and cooperating therewith to provide corona discharge when a source of high electrical potential is connected thereacross.

'2. An electrified, centrifugal gas cleaning device comprising a tubular conduit member providing a gas swirling and electrifying chamber, said conduit member having an open gas inlet end and an open gas outlet end, a discharge tube having an open gas inlet end and an open gas outlet end and having an outside diameter smaller than the inside diameter of said tubular conduit member, said discharge tube projecting into the outlet end of said tubular conduit member and being positioned coaxially with respect to the latter, means providing a restricted annular skimming orifice between said tubular conduit member and said discharge tube, a set of annularly arranged swirling vanes positioned against the inner wall of said tubular conduit member and spaced from the inlet end of said discharge tube towards the inlet end of said tubular conduit member, and a disc-like discharge electrode insulatedly supported in the space between said set of swirling vanes and the inlet end of said discharge tube.

3. An electrified, centrifugal gas cleaning device as defined in claim 2 wherein the outside diameter of said discharge electrode is substan- 8 tially the same as the inside diameter of said annularly arrangedset of swirling vanes.

4. An electrified centrifugal gas cleaning device as defined in claim 3 including means substantially preventing flow of gas through the central opening of said annularly arranged set of swirling vanes.

5. An electrified, centrifugal gas cleaning device comprising a tubular conduit member providing a gas swirling and electrifying chamber, said conduit member having an open gas inlet end and an open gas outlet end, a discharge tube having an open gas inlet end and an open gas outlet end and having an outside diameter smaller than the inside diameter of said tubular conduit member, said discharge tube projecting into the outlet end of said tubular conduit member and being positioned coaxially with respect to the latter, a skirt member carried on the outside of said discharge tube and fiaring outwardly towards the outlet end of said tubular conduit member and providing therewith a restricted annular skimming orifice, a first set of annularly arranged swirling vanes positioned against the inner wall of said tubular conduit member near the inlet end thereof, a second set of annularly arranged swirling vanes positioned against the inner wall of said tubular conduit member intermediate said first set of vanes and the inlet end of said discharge tube, a rod member extending longitudinally through said tubular conduit member and said discharge tube, mounting means external to said tubular member and said tube insulatingly mounting said rod with respect thereto, a first disc-like discharge electrode carried by said rod in the space between said first and second set of vanes, a second disc-like discharge electrode carried by said rod in the space between said second set of swirling vanes and the inlet end of said discharge tube, said discharge electrodes having a diameter substantially greater than said rod member having discharge points spaced from the inner Wall of said tubular conduit member and cooperating therewith to provide corona discharge when a source of high electrical potential is connected thereacross.

6. An electrified, centrifugal gas cleaning device comprising a tubular conduit member providing a gas swirling and electrifying chamber, said conduit member having an open gas inlet end and an open gas outlet end, a discharge tube having an open gas inlet end and an open gas outlet end and having an outside diameter smaller than the inside diameter of said tubular conduit member, said discharge tube projecting into the outlet end of said tubular conduit member and being positioned coaxially with respect to the latter, a skirt member carried on the outside of said discharge tube and fiaring outwardly towards the outlet end of said tubular conduit member and providing therewith a restricted annular skimming orifice, a first set of annularly arranged swirling vanes positioned against the inner wall of said tubular conduit member near the inlet end thereof, a second set of annularly arranged swirling vanes positioned against the inner wall of said tubular conduit member intermediate said first set of vanes and the inlet end of said discharge tube, a rod member projecting longitudinally intosaid tubular conduit member from the inlet end thereof and terminating at a point between said second set of vanes and the inletend of said dischargetube, mounting means positioned in front of the inlet end of said tubular conduit member insulatingly mounting said rod with respect thereto, a first disc-like discharge electrode carried by said rod in the space between said first and second set of vanes, a second disc-like discharge electrode carried by said rod in the space between said second set of swirling vanes and the inlet end of said discharge tube, said discharge electrodes having a diameter substantially greater than said rod member having discharge points spaced from the inner wall of said tubular conduit member and cooperating therewith to provide corona discharge when a source of high electrical potential is connected thereacross.

'7. An electrified, centrifugal gas cleaning device comprising a tubular conduit member providing a gas swirling and electrifying chamber, said conduit member having an open gas inlet end and an open gas outlet end, a discharge tube having an open gas inlet end and an open gas outlet end and having an outside diameter smaller than the inside diameter of said tubular conduit member, said discharge tube projecting into the outlet end of said tubular conduit member and being positioned coaxially with respect to the latter, a skirt member carried on the outside of said discharge tube and fiaring outwardly to wards the outlet end of said tubular conduit member and providing therewith a restricted annular skimming orifice, a first set of annularly arranged swirling vanes positioned against the inner wall of said tubular conduit member near the inlet end thereof, a second set of annularly arranged swirling vanes positioned against the inner wall of said tubular conduit member intermediate said first set of vanes and the inlet end of said discharge tube, a rod member projecting longitudinally into said discharge tube from the outlet end thereof and terminating at a point between said first and second sets of vanes, mounting means positioned at the rear of the outlet end of said discharge tube insulatingly mounting said rod with respect thereto, a first disclike discharge electrode carried by said rod in the space between said first and second set of vanes, a second disc-like discharge electrode carried by said rod in the space between said second set of swirling vanes and the inlet end of said discharge tube, said discharge electrodes having a diameter substantially greater than said rod member having discharge points spaced from the inner wall of said tubular conduit member and cooperating therewith to provide corona discharge when a source of high electrical potential is connected thereacross.

8. An electrified, centrifugal gas cleaning device comprising a tubular conduit member providing a gas swirling and electrifying chamber, said conduit member having an open gas inlet end and an open gas outlet end, a discharge tube having an open gas inlet end and an open gas outlet end and having an outside diameter smaller than the inside diameter of said tubular conduit member, said discharge tube projecting into the outlet end of said tubular conduit member and being positioned coaxially with respect to the latter, a set of annularly arranged swirling vanes positioned against the inner wall of said tubular conduit member and spaced from the inlet end of said discharge tube towards the inlet end of said tubular conduit member, and a disc-like discharge electrode insulatedly supported in the space between said set of swirling vanes and the inlet end of said discharge tube said disc-like discharge electrodes having a diameter substantially the same as the inside diameter of said swirling vanes.

HARRY A. WIN'IERMUTE.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 1,372,710 McGee et a1 Mar. 29, 1921 2,567,899 Warburton Sept. 11, 1951 2,594,805 Rommel Apr. 29, 1952