US3538865A

US3538865A - Burner means for eliminating smoke

Info

Publication number: US3538865A
Application number: US828113A
Authority: US
Inventors: Jerry S Lausmann
Original assignee: Individual
Current assignee: Individual
Priority date: 1969-05-26
Filing date: 1969-05-26
Publication date: 1970-11-10
Anticipated expiration: 1987-11-10

Description

United States Patent [72] Inventor Jerry S. Lausmann P.O. Box 1608, Medford, Oregon 97501 [21 Appl. No. 828,113 [22] Filed May 26,1969

Continuation-impart of Ser. No. 729,154, May 15, 1968, abandoned [45] Patented Nov. 10, 1970 [54] BURNER MEANS FOR ELIMINATING SMOKE 17 Claims, 24 Drawing Figs.

[52] U.S.Cl 110/18. 110/49, 110/119 [51 1 Int. Cl F23g 7/00 [50] Field ot'Search 110/7, 8. 18.49. 119. 120.28(Fl [56] References Cited UNITED STATES PATENTS 1,150,934 8/1915 Folger 2,717,563 9/1955 Sifrin 2,760.563 8/1956 Thompson 3,456,603 7/1969 Studler 3,476,062 ll/1969 Ramires 195,495 9/1877 English etal. 110/8 472.981 4/1892 Burden 110/49 744,131 1 H1903 Toohey 1111/49 2,350,991 9/1958 Thompson 110/18 3.163.133 12/1964 Montgomery 110/18 3,456,604 7/1969 Ehrenzeller et a1 110/8 3,460,489 8/1969 Ehrenzeller et a1 110/8 1,699,443 l/l929 Owen 110/49 2,804,031 8/1957 Douglass 110/114 150,911 5/1874 Thompson... 110/120 3,190,244 6/1965 Hoskinson...v 110/114 2,702.01 .1 2/1955 Atteberry 110/18 FOREIGN PATENTS 704,122 1961 France. 597,268 1934 Germany.

Primary Examiner-Kenneth W, Sprague Attorney-Buckhorn. Blore. Klarquist and Sparkman ABSTRACT: A tepee burner having means for concentrating at the burner axis the particulate matter which is produced in the combustion process, and means at the tepee outlet for collecting and drawing off the axial column of particle hearing gases while allowing the clean peripheral combustion gases to be discharged into the ambient air. Duct means return particle bearing gases to the lower portion of the burner where fan means inject such gases into the burner through a wall of flame to incinerate much if not all of the particulate matter, with the injection being carried out so as to aid the concentration of the particulate matter in the axial columnar portion of the rising combustion gases. Control means are provided for regulating the temperature of the returning combustion gases in relation to the temperature at the tepee outlet so as to mamtain the temperature of the burning pile at or near an optimum value, whereby to decrease the amount of particulate matter produced in the combustion process. The present invention also contemplates a method of burning waste products in a frustoconical burner comprising concentrating the particulate matter in the products of combustion at the vertical axis zone of the burner and drawing off the central columnar portion of the combustion gases whereby to remove substantially all of the particulate matter while allowing the clean gases to escape to the ambient air, returning the drawn off gases to the lower portion of the burner while incinerating much if not all of the particulate matter, the incineration being carried out at a temperature which is higher than, regulated by and related to the outlet temperature ofthe burner so as to maintain the burning pile at an optimum temperature whereby to decrease the amount of particulate matter produced in the combustion process.

Patented Nov, 10,1970 3,538,865

JERRY S. LAUSMANN INVENTOR BUCKHORN, BLORE, KLARQUIST 8. SPARKMAN ATTORNEYS Patehted Nov. 10, 1970 v 3,538,865

LAUSMANN JERRY lNl/E/VTOR B) BUG/(HORN, BLofigkLmou/sr a SPAR/(MAN ATTORNEYS Patented Nov. 10, 1970 3,538,865

Sheet 4 of? JERRY S. LAUSMANN INVENTOR BUCKHORN, BlORE, KLARQUIST & SPARKMAN ATTORNEYS Patented Nbv. 10, 1970 3,538,865

Sheet 5 of 7 JERRY S. LAUSMANN INVENTOR BUG/(HORN, BLO/PE, KLA/POU/ST 8 SPAR/(MAN ATTORNEYS Patented Nov. 10, 1970 3,538,865'

JERRY S. LAUSMANN lNVE/VTOR BUC/(HOR/V, BLORE, KLAROU/S T 8 SPAR/(MAN ATTORNEYS Patented" Nov. 10, 1970 3,538,865

356 FIG. 2

JERRY S. LAUSMANN lNVE/VTOR BUC/(HOR/V, BLOPE, KLAROU/ST a SPAR/(MAN ATTORNEYS 1 BURNER MEANS FOR ELIMINATING SMOKE This invention is a continuation-in-part of my copending application Ser. No. 729,l54, filed May 15, I968, now abandoned.

In many forested areas of the country in which sawmills are operated, the waste wood products from the mill are commonly disposed of by burning them in a tepee or wigwam burner. It is known that these tepee burners pollute the atmosphere with smoke because of incomplete combustion which unavoidably occurs. The State Sanitary Authorities in certain of these areas are putting intensive pressure on burner operators demanding that they eliminate pollution, but have not told the operators how this can be done in any practical sense.

I have studied the burning processes in tepee burners for some time and I have discovered that the axial portion of the combustion gases that rises from a burning pile of waste products contains more smoke than the peripheral portion. In trying to increase the concentration of the particulate matter in the axis zone of the column, l discovered a phenomena, namely, that as l increased the counterclockwise swirling action of the rising gases, the smoke particles, instead of being thrown outwardly as might be expected, tend to move toward the axis of the column to increase theconcentration of the particled matter in approximate proportion to the velocity of the swirling combustion gases. Obviously this increased concentration of the particulate matter at the axis of the column results in a cleaning action on the peripheral swirling gases. l have discovered that if I draw off the axial columnar portion of the combustion gases at or near the outlet of the burner, I remove a very high percentage of the particulate matter from the exhausting combustion gases and that l can allow the remaining peripheral gases to escape or exhaust to the ambient air and these gases are sufficiently clean that they are usually unobjectionable. l have also discovered that this central columnar portion of the rising combustion gases contains a substantial percentage of the volatile gases produced as an incident of, but not entirely consumed in, the combustion process, so that l collect not only a high-percentage of the particulate matter but also a substantial percentage of the unconsumed volatile gases. I take these drawn-off gases (with the entrained particulate matter) and conduct them downwardly and inject them into the lower portion of the burner through an intense wall of flame generated by the gas burner so as to (l) incinerate much if not all of the particulate matter, (2) ignite the volatile gases, and (3) elevate the temperature of the injected gases, which temperature is augmented by the heat resulting from the combustion of the particulate matter and the volatile gases. By controlling the amount of heat supplied by the gas burners in relation to the temperature demanded by sensor means at the exhaust of the burner, I can control the combustion environment within the burner and obtain near optimum conditions for combustion to take place.

l have further found that by injecting this drawn-off portion of the combustion gases into the burner in tangential relation to the fire pile, l can augment the swirling effect of the combustion gases, which as I have above pointed out, increases the concentration of the particled matter at the axial zone of the column of the combustion gases. I have further found that if in the collecting step, the gases are drawn off in a tangential direction to the exhaust of the burner, I can further augment the swirling action of the gases so that the overall effect is to substantially increase the number of convolutions the combustion gases travel. This increases the exposure time to the combustion heat within the burner and provides a greater opportunity for maximum combustion to take place before the gases escape.

The invention will be explained in connection with the accompanying drawings, wherein:

FIG. 1 is a diagrammatic view showing the operation of the burner of my invention;

FIG. 2 is a plan view of FIG. 1;

FIG. 3 is an elevational view of a burner of my invention, with parts broken away for convenience in illustration;

FIG. 4 is a fragmentary horizontal sectional view taken along lines 4-4 of FIG. 3;

FIG. 5 is an enlarged fragmentary vertical sectional view taken along line 5-5 of FIG. 3;

FIG. 6 is a fragmentary plan, view taken in the arrows 6-6 of FIG. 3,

FIG. 7 is a horizontal sectional view through the lower portion of the burner on a somewhat reduced scale as compared to FIG. 3 to show the control mechanism for the fire doors of the burner;

FIG. 8 is an enlarged fragmentary side elevation of part of a ductwork leg, parts being broken away and shown in section for convenience in illustration;

FIG. 9 is a fragmentary horizontal sectional view taken along line 9-9 of FIG. 3, FIG. 9 being on an enlarged scale as compared to FIG. 3;

FIG. 10 is a fragmentary vertical sectional view taken along line 10-10 of FIG. 9;

FIG. 11 is a fragmentary sectional view taken along line 11-11 of FIG. 3, on a scale larger than that employed in FIG. 3

the direction of FIG. 12 is a fragmentary vertical sectional view taken along lines 12-12 of FIG. 10;

FIG. 13 is a vertical sectional view of a burner forming an alternate embodiment of the invention;

FIG. 13A is an enlarged horizontal sectional view taken along line 13A-l3A of FIG. 13;

FIG. 14 is a horizontal sectional view taken along line 14-14 of FIG. 13;

FIG. 15 is an enlarged diagrammatic view taken along line 15-15 ofFIG. l3;

FIG. 16 is an enlarged, fragmentary, vertical sectional view taken along line 16-16 ofFlG. 15;

FIG. 17 is an enlarged, fragmentary, of a portion of the burner of FIG. 13;

FIG. 18 is an enlarged, vertical sectional view taken along line 18-18 of FIG. 13A;

FIG. 19 is an enlarged, vertical sectional view taken along line 19-19 of FIG. 13A;

FIG. 20 is a fragmentary, diagrammatic, top plan view of a burner forming an alternate embodiment of the invention,

FIG. 21 is an enlarged, fragmentary, vertical sectional view taken along line 21-21 of FIG. 20;

FIG. 22 is an enlarged, horizontal sectional view taken along line 22-22 of FIG. 21; and

FIG. 23 is an enlarged, fragmentary, taken along line 23-23 ofFlG. 21.

GENERAL DESCRIPTION FIG. 1 shows a tepee or wigwam burner having a frustoconical shell or housing 21 of the usual form. A conventional spark arrester screen 23 is provided over the outlet 24 of the burner. Inside the burner is a pile 25 of waste products, such as wood waste, which is burned and produces products of combustion which rise upwardly from the pile toward the outlet 24. The burner has the usual air openings 26 in the lower portion thereof to admit ambient air into the burner to supply oxygen to the burning pile. There is also a conventional underfire air system not shown to supply air to the interior of the pile.

As indicated hereinbefore, I have discovered that I can concentrate the particle laden gases P at the axial zone P-I of the burner by creating a distinct swirling action of the combustion gases within the burner and simultaneously clean the peripheral combustion gases C so that they can be discharged from the outlet 24 to the ambient air.

The structure for concentrating the particle laden gases in the axial zone includes a recirculating system for collecting the particle laden gases at the outlet and drawing them downwardly-and injecting them into the lower portion of the burner. This recirculation system includes a collector 27 which is connected to a pair of blowers work legs generally entitled 29 and 31. It might be mentioned here that the legs include collector outlet pipe sections 29a vertical sectional view vertical sectional view 28 by a pair of ductand 31a, which actually are permanently connected to and therefore are part of the collector 27, but they nevertheless function as part of the

ductwork legs

29 and 31.

The blowers 23 inject the particle laden gases into the burner at the lower portion thereof through injector nozzles 35. These injector nozzles are tangentially directed, as shown in broken lines in FIG. 2 to create a distinct swirling action of the combustion gases within the burner.

There are gas burners (to be described) which are carried by the nozzles 35 and which provide a wall of flame through which the particle laden gases are impelled, whereby much if not all of the particles are incinerated and the volatile gas constituents are ignited to produce needed heat. The temperature of the recirculated combustion gases is controlled, in a manner to be described, by a heat sensor 36 so as to maintain the environmental temperature of the pile 25 at or near the optimum burning value so as to avoid, as much as possible, the production of particles in the combustion gases, it being known that the particulate matter produced in the burning step decreases in proportion to the completeness of the combustion process.

I locate the

collector outlet pipes

29a and 31a in tangential relation to the collector 27 (and to the axial zone of the combustion gases) so that as these gases are drawn offin tangential relation whereby to create a zone of influence beneath the collector urging the combustion gases to spiral in the same direction as the gases are urged by the nozzles 35. Thus, the nozzles 35 operate at the lower portion of the burner to cause the combustion gases to swirl, while the

tangential outlet

29a and 31a operate at the upper portion of the burner to cause the combustion gases to swirl.

DETAILEDVDESCRIPTION Referring to FIG. 3, the fuel, i.e., waste wood or any other combustible material, is delivered to the interior of the tepee shell 21, through an opening 41, by any suitable means, such as for instance, a conveyor (not shown). The incoming fuel is delivered in such fashion that it falls onto the pile 25 to be consumed in the burning process, and in such process to produce products of combustion which rise upwardly (as previously described) toward the outlet 24 and the collector 27.

The collector 27 is in the form of an inverted cup having side walls which parallel those of the burner to avoid turbulence at the burner outlet 24. The diameter of the collector at the outlet 24 is approximately one-half of that of the outlet. The lower margin of the collector projects downwardly into the outlet of the burner as shown in FIGS. land 3.

The ductwork legs 29 and 311 of the recirculation system include the collector

outlet pipe sections

290 and 31a, a pair of elbows 29b and 31b, and a pair of

down stacks

29c and 31c. Each of the

legs

29 and 31 is supported by its own set of mounting units. Since the mounting units for one leg are identical to those of the other, only the units for leg 29 will be described in detail.

The mounting units for leg 23 include a top standard 27 and a pair of stand-

off brackets

48 and 49. The standard 47 includes a temperature expansion joint comprising a sleeve 51 (FIG. 8) slidably receiving the outer end of the outlet pipe 29a and the inner end of the elbow 29b. The sleeve rests on a saddle 53 (FIG. and is clamped in position by a curved band 55. The saddle is supported by shims 57 which are mounted on a shelf 59 (FIGS. 2 and 8) by a bolt 61 (FIG. 5). By reducing the number of shims, the level of the collector 27 may be changed with relation to the outlet opening 2 although it is normally contemplated that this adjustment will be used only in the initial setup of the burner and in fact may not be necessary.

The temperature expansion joint also includes a pair of rings 63 (FIG. 8) secured respectively to the adjacent ends of the pipe section 29a and elbow 2%. Threaded steel rods 65 pass through holes in the rings, and nuts on the stud bolts hold the pipe ends in position within the sleeve 51.

The lower end of a elbow 29b slidably extends into a sleeve 67 (FIG. 8) of second temperature expansion joint which is supported by the bracket 48. The upper end of the down stack 29c also slidably extends upwardly into the sleeve 67.

Near its upper end the down stack 29c has a ring 73 (FIG. 3) secured thereto. A turnbuckle hanger 7ll connects the ring 73 to the bracket 48 to support the down stack 29c. When the equipment is initially put in operation. as the temperature rises and expansion of the parts occurs, the turnbuckle hanger 7H may be adjusted to lower the down stack, as demanded, to ensure against buckling contact between the upper end of the down stack 29c and the lower end of the elbow 29b.

A damper 81 is provided in the down stack 29c and has a mechanical thermostat 82 to control the position of the damper butterfly 81a. When the temperature of the combustion gases flowing through the down stack 2% reaches a predetermined value, the mechanical thermostat 82 will be activated to move the damper butterfly 81a toward its closed position. This operation will continue until the butterfly 31a is in its fully closed position, unless the temperature rise ceases.

As will be explained hereinafter, the blower 28 operates continuously. Thus, when the damper Si is closed, the blower receives air through an auxiliary damper 83 mounted in a pipe section 84 on the manifold housing 85 of the blower. The damper 83 is weighted so that it automatically opens an extent approximately proportional to the degree of closure of the damper 8B. Thus, cool ambient air will be provided through the auxiliary damper 83 to mix with the recirculated combustion gases to have a cooling effect on them and will tend to have a cooling effect on the pipe 25 to tend to maintain the fire pile temperature at or near optimum value. This maintenance of the tire pile temperature near its optimum value is important because the amount of particled material produced in the burning process is very small at or near the optimum combustion temperature within the burner.

FIG. 6 shows that the damper 83 has a pivot shaft 91 which has an angled extension 93 equipped with a weight 95 which can be threaded along the extension 93 to attain the desired response of the damper.

Referring to FIG. 11, the lower end of the down stack 29c slidably extends into the manifold 85 through a friction joint 101. The latter has compressible packing I03 held in frictional contact with the down stack 290 by clamp rings E05 carried by the upper end of the manifold 85.

Referring to FIGS. 3 and 912 the centrifugal blower 28 includes a boxlike case 1111 having trapezoidal side plates 213 and 1M, and rectangular outer, inner and

bottom plates

115, 117 and 119, respectively. A radial-blade rotor 121 has a mounting sleeve I23 through which extends a drive shaft 125. r

The latter is nonrotatably secured to the sleeve I23 and is rotatably mounted by bearings 127 on the

side walls

113 and 114 of the blower case HI.

There is a flow divider for the blower 28. The divider comprises upwardly converging top walls 131 (FIG 11), and vertical

flat side walls

135 and 137, of the same trapezoidal shape (FIG. 10) as the case side walls 113 and HM (FIG. 3). The recirculated gases are divided by the flow divider to flow downwardly in two separate paths in the spaces provided between the flow divider walls R35, 137 and the case walls 113 and IM. A generally U-shaped guide 139 is secured to and tits between each of the

walls

135, 137 and the adjacent case wall.

These guides confine the paths of travel of the incoming particle laden gas so that they enter axially directly into the rotor 121 through inlet ports I41 and I43 provided, respectively, in the wall 137 and an access plate 144 which is bolted in place on wall I35. Thus, the blower 28 has a dual axial intake system.

There is a spiral housing M5 which surrounds the rotor 121 and which has an outlet 147 of rectangular cross section (FIG. 12) which projects through the inner case wall 17. Housing fits between the

walls

335 and 137 and is secured thereto.

End rings 151 are secured to the end edges of the blades 153 to strengthen the rotor. The blades are recessed at 155 at each inner end corner portion (FIG. 9) to allow for the ready ingress of combustion gases.

The rotor 121 may be readily removed for inspection or repair by removal of the case side plate 113 and the access plate 144. I

The recirculated combustion gases are discharged by the blower 28 into the outer end of the nozzle 35 and flow through the nozzle and exit the nozzle in surrounding relation to an axially located Eclipse gas burner 161 (FlG. 4). The burner is supplied with natural or LP. gas by piping 163, the gas being premixed with sufficient air so that no extra oxygen is required for its burning and so no objectionable carbon monozide is produced when it burns. The gas burner emits a hot flame of a size such that most or all of the particle laden combustion gas must pass through the flame. The flame incinerates much if not all of the entrained particles and ignites substantially all of the volatile gas constituents of the recirculated combustion gases.

FlG. 4 shows a gas burner ring 165 on the nozzle. This ring receives natural or L.P. gas from the same source as does gas burner 161, the gas being mixed with air before being burned. The burner ring provides a series of radially inwardly projecting flame jets to provide a wall of flame through which the recirculated combustion gases must pass to preheat the particles prior to their being incinerated by the burner 28. Burner ring 165 may be used in certain installations as an optional device and may be left out of others. 9

FIGS. 3 and 4 show that the outlets of nozzles 35 are directed generally tangentially relative to the tepee burner and in a horizontal direction. To enable the angle relative to the horizontal to be varied, the outer end of the nozzle has an adjustment ring 171 (FIGS. 3, 10-and 12) fixed thereto. This ring has arcuate slots 172 (FIG. 12) to receive stud bolts 173. The latter thread into the wall 117. A retainer ring 175 has a sliding fit on the nozzle 35 and has holes 177 to accommodate the stud bolts 173. Nuts .79 retain the nozzle in any position of adjustment. Adjustment is permitted upon loosening the nuts. 1n the event the extent of adjustment permitted by the slots is not sufficient, the nozzle may be removed from the stud bolts and turned so that the stud bolts pass through different slots than before.

The piping 163 (FIG. 4) is shown with a flexible section 1630 which will accommodate adjustment of the position of the nozzle 35. lnstead of a flex joint, the piping could extend through a slot in the tepee wall, and a shield on the piping employed to close the open portion of the slot in any position of the limited range of adjustment of the nozzle. Longer or shorter sections in the piping would be used to accommodate the new nozzle setting.

A guard 181 is provided over each nozzle 35 to prevent damage to the nozzles 35 that might otherwise result if they were exposed and struck by the larger objects in the waste wood or other material which is fed into the tepee burner through the infeed opening 41.

Ambient air, admitted to the interior of the tepee burner through the openings 26, is controlled by doors 191 (FIGS. 3 and 7). Each door is mounted for pivotal adjustment by a vertically extending shaft 193,

The positions of the doors are controlled by an adjusting ring 195 which is supported in surrounding relation to the lower portion of the tepee burner by roller units 197 (FIGS. 3 and 7). Each door has a fixed arm 201 which projects outwardly therefrom and which is formed with a slot 203 through which passes a pin 205 in the adjusting ring.

The position of the ring and thus of the doors is changed by a power unit 207 which, per se, is of conventional form, being like the trim tab motor used on aircraft. It is pivotally connected to the ring 195 and an arm 209 fixed to the burner shell 21. The unit is of telescopic form and contains a reversible DC motor connected to a worm gear drive which causes extension of the power unit when the DC motor is driven in one direction (to open the doors 191) and causes contraction of the power unit when the DC motor is driven in the opposite direction (to move the doors toward their closed positions). The power unit is controlled by a reversing switch (no shown) having a neutral position.

The following description is exemplary of the operation of my burner (and not intended to be limiting). Let it be assumed that the temperature of the exhaust gases of the burner is in the range of 775F. and is rising. When the temperature reaches approximately 850F. (which reflects that the pile 25 is in the optimum temperature range in which the combustion process is sufficiently complete that little particulate matter is produced), the sensor 36 will send a signal to a stage type control circuit (not shown), but of conventional design, which will actuate a solenoid valve (not shown) to cut off the supply of fuel gas to the burner 161 (and also the burner ring 165 if it is employed). However, the blowers for the burners will remain in operation, as will the blowers 28. Thus, the burner blowers will inject cool ambient air into the tepee burner 21. This, and the absence of the heat which previously had been produced by the burners 161 (and 165) means that the recirculated combustion gases introduced into the tepee burner by the blower 28 will be distinctly cooler than they previously were. This will create a cooler environment for the burning pile 25 and in many instances will bring the exhaust temperature down below 850F. If the temperature continues to drop and falls below 800F., the heat sensor circuit will actuate the solenoid valves for the

burners

161 and 165 to turn the burners on again to tend to maintain the exhaust temperature in the optimum range. Should the temperature drop below 750F., the power unit 207 will be actuated to close the doors 191 to substantially cut off the supply of ambient air through the openings 26. This action, in most instances, will cause a heat build up to bring the operating temperature of the tepee burner back within its optimum range.

ln some instances, the cutting off of the fuel gas from the

burners

161 and 165 may be insufficient to stop the rise of the temperature within the tepee burner. Should the exhaust gas temperature reach 900F., the thermostats 82 will close the dampers 81 to cut off the supply of the recirculated gases to the lower portion of the tepee burner. Since the blowers 28 are still operating, dampers 83 will open so that blowers 28 now blow cool ambient air into the lower portion of the tepee burner. This action, in practically all cases, will reduce the exhaust temperature to within the desired range.

In unusual operating conditions, should the closing of the dampers 81 not stop the temperature rise within the tepee burner, the heat sensor circuit will energize an alarm before the temperature reaches the danger level (the level at which structural damage to the burner would occur) to enable emergency measures to be taken (such as wetting down the pile, etc.)

A standby heat sensor 36a (FIG. 1) is provided in case sensor 36 is damaged or becomes inoperative for any reason.

EMBODIMENT oF'Fios. 13TO 19 A tepee or wigwam burner shown in FIGS. 13 to 19 includes a frustoconical shell or housing 221 of the usual form, to outlet 224 of which is secured a stack 222 having six rows of bustion which rise upwardly from the pile. Ambient air from the atmosphere outside the burner and particle layer gases to be recirculated are blown tangentially or chordally into the housing through nozzles 235 by blowers 222 which direct the air and gases chordally relative to the housing as best shown in FIGS. 13 and 13A in a generally counterclockwise direction in the housing when viewed from the top. The particle laden gases are taken from an axial or central column of particle laden gases P by a frustoconical, crown collector 227 supported by

ductwork legs

229 and 231 leading to the inlets of the blower 228. The mixture of ambient air and particle laden gases are thus injected into the peripheral portions of the flames from the the pile 225 to complete combustion of the particles and add oxygen to the tire. The tangential injections from the nozzles aid or reinforce the natural coriolis effect and cause the heated gases from the tire and those introduced by the nozzles 235 to swirl around and upwardly in multiconvolution spirals to transfer substantial portions of the heat thereof to the housing to heat all portions of the housing substantially uniformly to prevent formation of hot spots, and the housing dissipates the heat by convection and radiation. This keeps the temperatures in the interior of the burner and the temperatures of the gases discharged from the burner through the stack 222 quite low.

The stack 222 may have a fire screen 239 at the discharge end thereof. The stack preferably intensifies the draft and increases the intensity of the burning.

The lower portion of the housing is secured to arcuate angle members 240(F1G. 13), which are secured in circular form to a circular concrete base 241 by turnbuckles 2 12. The base 241 confines a bed 243 of rock which may be decomposed granite.

The blowers 228, except as brought out below, are substantially the same as the blowers 28. The blowers 228 and

ducts

229 and 231 are supported by stools 245, and each blower includes

shelves

246 and 247 fixed to blower housings 248. The shelves support motors 249 driving impellers of which shafts 250 extend through the blower housings driving impeller blades (not shown) in the blower housings. The shafts 259 are journaled in outboard, pillow block bearings 251 mounted on the shelves, and heat slingers 252 keyed to the shafts 259 are positioned between the bearings 251 and the housing 221 to shield the bearings from the heat. The slingers have helical air impelling slots 253 (FIG. 19) and act as fans to draw air from the bearings and impel it toward dampers 254 (FIG. 3) in the walls of the blower housings 248. The slingers taper from thick at the hubs thereof to thin at the outer peripheries thereof. Each damper 254 (FlG. 18) allows the ambient air to be drawn into the housing 248 by the impeller member in the housing and includes a closure disc 255 having openings 256 and rotatable on the shaft 250. The disc 255 is adapted to be turned on the shaft to vary as desired the extent that the openings 256 overlap or register with openings 257 in the adjacent wall of the housing 248. A headed pin 258 extends through an arcuate slot 259 in the disc 255 and is releasably secured to the wall of the housing 248 to normally lock the disc to the housing in a selected position of adjustment.

The nozzles 235 (FlGS. 13 and 13A) are angular sections of pipes or ducts having flanges (not shown) releasably bolted to the housings 248 and extending loosely through openings 260 in the housing 221 and in position in which the axes of the nozzles lie in a horizontal plane. If desired, the nozzles can be mounted in positions extending chordally clockwise rather than counterclockwise. Alternately the nozzles may be straight rather than angular and the blowers 228 turned to positions in which the nozzles extend chordally into the housing 221, like the discharge portions of the angular nozzles 235 do.

To further increase the intensity, rate and completeness of combustion of the pile 225, a tangential underfire system is provided in the burner. The underfire system includes tripod or triad grouped nozzles 270 (FIGS. 13 and 1618) arranged in

groups

271, 272, 273 and 274 around stanchions 275. Each nozzle includes a straight, inclined pipe section 276 having downwardly directed nozzle or orifice outlet tubes 277 on the underside thereof of progressively decreasing cross-sectional area proceeding upwardly along the pipe section. The pipe sections 276 are supported by vertical portions 278 having secured thereto caps 279 and spacer discs 280. The caps 2'79 fit into dished flange portions 281 of socket members 232, and the lower discs 280 bear on collars 283 resting on the ends of angular distributing pipes 284 secured to cylindrical couplings 285 having end caps 236 and supplied with air from

branch pipes

287, 288, 289 and 290 (H0. leading to

headers

291 and 292. Blowers 293 and 294 having adjustable valves 295 and 2% blow ambient air into the headers and to and through the nozzles 2'70, and a booster blower 297 is connected by ducts 298 and adjustable valves 299 to add further ambient air to either, both or neither of the headers when and if necessary. The

ducts

287 and 288 are of the same diameter to supply equal quantities of air to the groups 27R and 272, and equal quantities of air are supplied to the groups 273 and 2'74. .The nozzles 270, stanchions 275 and caps 27) are of high melting point materials, such as stainless steel, titanium, ceramic or ceramic coated metal.

The effective diameter of the collector 227 is that of the lower edge portion of the collector, and, for most efficient operation of the burner, the effective diameter of the collector should be about 82 percent of the diameter of the portion of the housing 221 at the same level as the lower edge of the collector. The gases passing to the outside of the collector travel on up and out of the burner, these gases containing little or no particles not fully oxidized. The gases P in the axial column and containing particles not fully oxidized travel upwardly into the collector and all these particles and substantially all the gases carrying these particles are drawn into the

ducts

229 and 231 and are injected chordally or substantially tangentially into the outer peripheral portions of the flames of the pile 225 to complete the combustion of the particles, additional air being drawn into the particle laden gases through the dampers 254.

The shell 221 has a service door and a charging door therein like those of the shell 21. While not included as shown, the shell 221 also may have overfire air doors like the doors 191, if desired. The collector 227, the stack 222, the

ducts

229 and 231 and the blowers 228 may be installed in existing tepee burners to greatly improve the efficiency thereof. This also is true of the tangential underfire air system of H68. 13 and 15 to 17.

EMBODIMENT OF FIGS. 2023 A burner shown in FIGS. 2t123 and forming an alternate embodiment of the invention is like the burner of FIGS. 13 to 19 except for a tangential underfire air system of the burner of FIGS. 20-23. The burner of FIGS. 2ll23 burns a pile 325 and includes underfire burners or

nozzles

326, 327 and 328 arranged in

groups

331, 332, 333 and 334 of three nozzles each. Each group of three nozzles is connected by a pipe 329 to a distributor or manifold cylinder 335 covered by a cap 336 and supplied by a vertical pipe 337. The pipes 337 leading to the groups 372 and 332 are connected to branch

ducts

338 and 339 leading from a header 344 from a blower (not shown) taking ambient air from outside the burner. The pipes 337 leading to the groups 333 and 334, are connected directly to a header 341 from a blower (not shown) taking in ambient air from outside the burner.

Each

nozzle

326, 327 and 328 includes a burner pot 359 partially embedded in a bed 351 ofdecomposed granite or like material, and also includes a caplike grate 352. Each grate 352 includes an imperforate cap or disc 353 of a greater diameter than the outside diameter of the pot 350 and six radial diffuser or spacer plates or legs 354 integral with the cap. The pots and grates preferably are of a high melting point metal, such as, for example, cast iron containing a higher than usual percentage of nickel. The plates are in equiangular positions 60 apart and fit slightly loosely into upwardly opening vertical slots 355 in the pots 350. Each cap 353 defines, with the sides of the plates 35d and top edge 356 of the pot 3S0, horizontally directed orifices 357 for passage of the air into the pile 325. The slots and the plates hold the grate substantially centered on the pot.

The effective size of the orifices of each of the

nozzles

326, 327 and 328 is determined by the spacing between the top 356 of the pot 350 and the bottom of the cap 353, which spacing is determined by the depth of the slots 355. To achieve optimum distribution of the underfire air to the pile, each orifice of the nozzles 326 is made substantially smaller than each orifice of the nozzles 327 and each orifice of the nozzles 327 is made substantially smaller than each orifice of the nozzles 328. This is accomplished by making the depth of each slot 355 in the pots 350 of the nozzles 326 less than the depth of each slot in the pots of the nozzles 327 and making the depth of each slot of the pots of the nozzles 327 less than the depth of each slot in the pots of the nozzles 328. Preferably these depths are made such that the total cross-sectional orifice area of each group of the

nozzles

326, 327 and 328 is such relative to that of the other groups of the nozzles that the total flow of air through the nozzles 326 is about three times the total flow through the nozzles 328 and the total flow of air through the nozzles 327 is about twice that of the nozzles 328. The

nozzles

326, 327 and 328 lie on concentric circles centered relative to the pipe 325, there being three nozzles 326 on the smallest, innermost circle, three nozzles 327 on the intermediate circle and six nozzles 328 on the largest, outermost circle.

Each grate 352 is larger in diameter than the pot 350 so that, as best shown in H0. 22, the cap 353 and the plates 354 project radially beyond the pot to protect the orifices 357 from clogging by clinkers, and, as best shown in FIG. 21, the upper surface of each of the portions of the bed 351 surrounding the pots 350 slopes downwardly away from the pot at an angle of about l with the horizontal to disperse slag.

The shell 321 has a service door and a charging door like the shell 21. While not included as shown, the shell 321 also may have overfire air doors like the doors 191, if desired.

lclaim:

1. The method of reducing or eliminating the production of smoke and like particulate matter from the combustion products exhausted from a burner which is of generally upwardly tapering form and which has an outlet at its upper end, and wherein the material being burned is located generally centrally of the burner at the lower portion thereof, comprismg:

swirling the gases in the burner around in a predetermined direction to concentrate the particles at the axial zone of the burner;

allowing the peripherally located gases to escape from the outlet of the burner;

capturing at the outlet the particle laden gases at the axial zone of the burner; and

eliminating a substantial portion of the particles prior to releasing such gases to the atmosphere.

2. The method of claim 1, wherein:

the captured gases are conveyed exteriorly of the burner to the lower portion thereof and injected into the burner; and applying incinerating heat, independent of that created by the burning process, to the particulate matter to incinerate it.

3. The method of claim 2, wherein:

the imparting step is at least in part provided by injecting the captured gases into said burner in a circumferential direction;

wherein the imparting step is at least in part provided during the capturing step by drawing off the particle laden gases in a direction tangentially related to the axial zone of the burner; and

wherein the incinerating step occurs concurrently with the injection of said captured particle laden gases into said burner.

4. The method of claim 2, wherein the exhaust temperature of the burner is sensed and the incineration step terminated when the exhaust temperature reaches a predetermined value.

5. A burner having:

a shell of generally upright tapering form with an outlet at its upper end;

a gas recirculation system ially at the outlet; ductwork means leading from said collector to the lower portion of said shell exteriorly of the shell; and

blower means in said ductwork for creating a down draft to capture the axial zonal parts of the rising products of combustion and inject them into the lower portion of the burner in generally tangential relation to the burner.

including a collector disposed ax- 6. A burner in accordance with claim 5, wherein said ductwork has an end at said collector located in tangential relation to said axial zone and has a lower end located circumferentially of said burner whereby to cause a definite multiconvoluted swirl of the combustion gases to concentrate the entrained particulate matter of the gases at the axial zone so that they are captured and recirculated by said recirculating system.

7. A burner in accordance with claim 6 wherein there are incinerator means at said lower end for incinerating the particled matter and igniting the volatile constituents of said recirculated gases.

8. A burner in accordance with claim 7 having a heat sensing means for sensing the exhaust temperature of the combustion gases and terminating the operation of said incinerator means whenever said exhaust gases reach a predetermined temperature. I

9. A burner in accordance with claim 7 having a first damper means in said ductwork to at least substantially close off said ductwork when the exhaust gases reach a predetermined temperature, and ambient air damper means to open when said first damper means is closed.

10. A burner in accordance with claim 9 wherein:

said shell has ambient air doors in the lower portion thereof;

and

means responsive when the exhaust temperature reaches a predetermined level to actuate said doors.

11. in a method of burning waste products:

burning a pile of waste products to create a column of rising gases having a portion thereof containing particles which have not been completely burned;

swirling the gases within the burner in a predetermined direction to concentrate the particles at the axial zone;

drawing the particle laden gases in said axial zone out of said column;

mixing ambient air with the particle laden gases drawn out of said column to form a mixture; and

blowing said mixture around the periphery of the fire of said pile.

12. The method ofclaim 11 wherein said blowing is directed tangentially around the periphery of said fire.

13. The method of claim 12 wherein said column is confined externally and the direction of said blowing is such as to reinforce the coriolis effect.

14. In a burner:

a generally upright shell open at its top and adapted to surround a pile of burning waste products in the lower portion thereof and guide gases upwardly from the pile; and

recirculating means including withdrawing means for withdrawing from the shell the central portion of the gases at a point substantially above the pile and'also including injecting means for injecting the withdrawn gases tangentially into the shell.

15. The burner of claim 14 wherein the recirculating means includes duct means leading from the upper portion of the shell to the exterior thereof, downwardly along the exterior of the shell and through the lower portion of the shell, and blower means including an impeller in the duct means, a shaft mounting and keyed to the impeller and extending through opposite sides of the shell, outboard bearing means positioned outside the shell and electric motor means with heat slingers outside the shell and driving the shaft.

16. A tepee burner having a shell or generally upright tapering form with an outlet at its upper end, and adapted, at its lower portion, to surround a centrally located burning pile of waste products:

swirl inducing means for causing the gases within the burner to swirl around counterclockwise as they rise toward the outlet of the burner whereby to retain particled matter at the central zone of the burner and to cause other particulate matter not so located to move toward the central zone of the burner;

a closed, inverted, generally cup-shaped collector which is wider than it is high;

means mounting the collector within the upper portion of the burner shell with the lower edge of the collector disposed in spaced relation below the outlet of the burner and in spaced relation to the side wall of the burner shell,

outlet of the burner whereby to retain particled matter at the central zone of the burner and to cause other particulate matter not so located to move toward the central zone of the burner;

to define an annular gas outlet space, whereby the relaan inverted,generally cup-shaped collector; tively clean peripheral rising gases are discharged from means mounting the collector within the upper portion of the burner, and the central portion of the rising gases the burner shell with the lower edge of the collector travel to the collector; disposed in spaced relation below the outlet of the burner the distance between the lower edge of the collector and the and in spaced relation to the side wall of the burner shell.

o posed wall of the burner shell being only a minor f to define an annular gas outlet space, whereby the relation of the diameter at such l wer edg wh b h tively clean peripheral rising gases are discharged from lower portion of the collector defines an area constituting h burner n the Centr l P rtion f he rising gases a major portion of the area of the burner shell at the locatravels to the Collector; tion of such lower edge of such collector; Said Collect ng Wider than it is high; said collector having outlet means; the distance between the lower edge of the collector and the said swirl inducing means including overfire air blower pp Wall f the b rner Shell being only a minor fracmeans near the lower ortio fth b tion of the diameter at such lower edge, whereby the injection nozzle means connected to the blowers and having lower Portion of the collector defines an area constituting outlet means di d i hi h burner h ll d amajor portion ofthe area of the burner shell at the locaranged to discharge gases nonradially into the burner in a tion of Such lower edge of such Collector? counterclockwise direction substantially the same as that Said collector having outlet means; of the swirling gases; said swirl inducing means including overfire air blower duct means extending laterally from the outlet means and means hear the lower Porticm Ofthe burner;

then downwardly to i blower means to f ilit t injection nozzle means connected to the blowers and having withdrawal of gases from said collector and to discharge outlet disposed Within h h them into the burner shell whereby to return the major ranged to h h h hohmdlhh) a portion of the unburned particles to the burner shell for l f s dlrcclloh suhstahhhhy {he Same as that consumption by the heat of combustion, and also to augof the swh'hhg B F memthe swirling action fth gusesinthe burnenand duct means extending from the collector outlet means to said blower means to facilitate withdrawal of gases from means for mixing ambient air with the returned gases 17. A smoke eliminating attachment for a tepee burner havsaid collector and to discharge them into the burner shell whereby to return the major portion of the unburned paring a shell of generally upright tapering form with an outlet at its upper end, and adapted, at its lower portion, to surround a centrally located burning pile of waste products, said attachment comprising:

swirl inducing means for causing the gases within the burner to swirl around counterclockwise as they rise toward the ticles to the burner shell for consumption by the heat of combustion, and also to augment the swirling action of the gases in the burner; and

means for mixing ambient air with the returned gases.