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Publication numberUS3831535 A
Publication typeGrant
Publication dateAug 27, 1974
Filing dateNov 2, 1973
Priority dateNov 2, 1973
Publication numberUS 3831535 A, US 3831535A, US-A-3831535, US3831535 A, US3831535A
InventorsBaardson A
Original AssigneeMill Conversion Contractor Inc
Export CitationBiBTeX, EndNote, RefMan
External Links: USPTO, USPTO Assignment, Espacenet
Wood waste burner system
US 3831535 A
Abstract
The present invention provides a system by means of which waste wood, as well as the fumes emitted by veneer being dried, are burned in such a manner as to basically accomplish two things, namely, provide large amounts of heat energy that was formerly wasted and, secondly, substantially reduce the emission of pollutants into the atmosphere. The system finds particular application to the lumber mill industry.
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Description  (OCR text may contain errors)

United States Patent 1191 Baardson Aug. 27, 1974 [54] WOOD WASTE BURNER SYSTEM 3,064,592 ll/l962 12116136161 110/102 x 3 0,09 3967.] ..IO [75] Inventor: Andrew Baar Beaverton, 3132:7524 6ii968 1i0i Wash- 3,675,600 7/1972 Jones ll0/8 [73] Assignee: Mill Conversion (Iontractor, Inc.,

Hillsboro, Oreg. Primary ExaminerKenneth W. Sprague Attorney, Agent, or FirmWeinstein, Robbins, [22 Flled: Nov. 2, 1973 Emmy, Sam & Kay [21] Appl. No.: 412,474

[57] ABSTRACT 52 vs. C] 110/8 0, 110/8 A, 110/102 The Present invention Provides a System y means of 51 1111. 1:1. F23g 7/00 which Waste Wood, as Well as the fumes emitted y [58] 116111 of Search 110/7 R, 7 A, 8 R, 8 A, heer being dried, are burned in Such a manner as to basically accomplish two things, namely, provide lar e 110/8 C, 102 g amounts of heat energy that was formerly wasted and, [56] References Cited secondly, substantially reduce the emission of pollut- UNITED STATES P E ants. hi $3 591? Th l i El mfifiq .Pil'gq lfi I application to the lumber mill industry. 2,614,513 l0/l952 Miller et a1. llO/7 0 3,022,753 2/1962 Montgomery 110 102 X 15 Clams, 9 Drawmg Flglll'es TO ATMOSPHERE 22 r ur .l' BOILER RAW WE $55 fifitifilifi 11 WOOD; METERED I COMBUSTlON BLENDlN6 SEPARATOR J 6111111111512 E CHAMBER 111m" 1 1 l.-- J H01" DAMPER 5 r QIQPEZALP NATURAL GAS SECONDARY HOT 014 PROPANE A112 6A5 6 SOURCE 5011120;

DRYER FUEL METERlNG &l6NAL 21 PATENTED AUG 2 7 I974 SIEU 3 0f 5 24k M 4 ZOFWDMEOU ll WOOD WASTE BURNER SYSTEM The present invention relates to the lumber mill field in general and more particularly relates to a system for the effective utilization of wood waste material and other by-products of the lumber mill industry.

Lumber mills generate tons of waste wood daily and not all of it can be used for barkdust, chipboard or other commercial products. More particularly, in the manufacture and processing of lumber and lumber mill products, various kinds of wood materials are developed with which little can be done and which are therefore looked upon and treated as waste. For example, in a plywood mill, the surface of the plywood is finished by sanding the plywood and, as a result thereof, there is produced a sander dust that is difficult to handle because it is stringy, balls up, has a tendency to bridge, is difficult to measure quantitatively, presents a fire and explosion hazard, and is generally a nuisance to handle. There is also produced a substantial quantity of waste wood known as hog fuel, so called because it has been sized by being fed through a chipper or hog. In addition, there are various other wood waste materials produced as by-products, such as bark, shavings, trimmings, sawdust, and the like. Some of the materials mentioned are usually wet or damp to one degree or another, such as the bark and sawdust, which further complicates the practical use of them. Accordingly, in the past, these materials have gone as waste wood and, in the main, have been gotten rid of by burning them in what are known as Wigwam burners. Unfortunately, however, one of the effects of this type of burning has been the injection or emission into the atmosphere of large amounts of pollutants, such as, smoke and ash, various kinds of chemical emissions, uncombustible particles, and the like.

On the subject of air pollution, it should also be mentioned that in the process of drying veneer or green lumber, fumes are emitted from the wood that in the past, have been vented into the atmosphere. These fumes are of a combustible nature but their use as a possible heat energy source has been totally wasted. Furthermore, because of the chemicals in the fumes, they have not only been unsightly, but also obnoxious and deleterious in a number of respects. Considering the large volume of these fumes that are daily vented into the atmosphere, it will be recognized that these fumes have materially contributed to what has come to be known as the air-pollution problem.

Needless to say, any system that could effectively utilize these waste wood products and the fumes, and use them in a manner that would reduce pollution of the air we breathe, would certainly constitute a significant step forward in the lumber mill industry. The present invention provides such a system, the essence of the system lying in utilizing and consuming both the waste wood and the fumes as a fuel, the heat generated thereby being used to dry the veneer or raw wood, to operate a boiler, etc., with the remainder being fed into the atmosphere devoid of most pollutants. More particularly, in a system according to the present invention, the waste wood is first reduced to a dry powdery form so that it can be used as a fuel. It is then fed to a rather unique dual-chambered burner to which the fume emissions are also fed, the wood and the fumes being fired and burned in the burner to produce a very sub stantial amount of heat energy. The products of combustion are then fed to a unit that separates out the impurities from the hot gases, a portion of the clean hot gases then being directed to the dryer from which the fumes are channeled back to the burner, as previously mentioned. The remaining hot gases may either be vented to atmosphere or else use-d elsewhere as an energy source, such as to operate a boiler system or the like.

In addition to the obvious benefits to be derived from the mentioned system, such as the reduction in air pollution and the provision of additional heat energy, there are many additional advantages to be gained from it. For example, propane or natural gas has customarily been burned to provide the heat required in a dryer. The present invention has very materially reduced this need for propane and natural gas as a fuel, with the result that very substantial savings of money can be realized from it.

It is, therefore, an object of the present invention to provide a system that makes effective use of waste wood and veneer or raw wood gas emissions as a fuel.

It is another object of the present invention to provide a system that substantially eliminates pollution of the air that in the past came about as the result of the burning and drying of wood products.

It is a further object of the present invention to provide a system that converts wood waste to heat energy.

It is an additional object of the present invention to provide a system that eliminates the need for a separate fire system within a veneer dryer.

It is still another object of the present invention to provide a system wherein veneer-dryer stack emissions are returned to a burner for combustion as a fuel.

It is a further and additional object of the present invention to provide a system for the lumber mill industry that controls emissions to the atmosphere.

The novel features which are believed to be characteristic of the invention, both as to its organization and method of operation, together with further objects and advantages thereof, will be better understood from the following description considered in connection with the accompanying drawings in which an embodiment of the invention is illustrated by way of example. It is to be expressly understood, however, that the drawings are for the purpose of illustration and description only and are not intended as a definition of the limits of the invention.

FIG. 1 is a block diagram of the basic units or components of a system according to the present invention;

FIG. 2 illustrates the FIG. 1 embodiment in greater detail in that it breaks down the blocks in FIG. 1 to the apparatus included in them.

FIG. 3 is a cross-sectional view ofthe burner unit included in and playing such a vital role in a system according to the present invention, and illustrates the combustion and blending chambers therein.

FIG. 4 is a front view of one of the elements included in the construction of the FIG. 3' burner unit;

FIG. 5 is a side view, partially in cross-section, of the wood fuel supply and dispersion apparatus included in the construction of the FIG. 3 burner unit;

FIG. 5(a) is an end-view of the FIG. 5 apparatus;

FIG. 6 is an elevation view, partially in crosssection, of a reverse flow particulate separator that constitutes one of the basic units shown in FIG. 1.

FIG. 6(a) is a cross-sectional view of the FIG. 6 apparatus taken along the broken line AA and in the direction of the arrows at the ends thereof; and

FIG. 7 is a block diagram showing a modification to a portion of the FIG. 1 system.

For a consideration of the invention in detail, reference is now made to the drawings wherein, in FIG. 1, a system according to the invention is shown to basically comprise a metered wood fuel source 10 coupled on its input end to receive raw waste wood, such as the hog fuel, bark, shavings, etc., mentioned earlier, and coupled on its output end to a burner 11 having two chambers, namely, a combustion chamber 12 and a blending chamber 13. As will more fully be described hereinbelow, the raw waste wood is dried and ground up in wood fuel source 10 to a fine powdery form, and thereafter metered out to the burner on the basis of need as determined by the operating conditions of the system.

The wood fuel, along with an ample supply of air, is conveyed to combustion chamber 12 where it is combusted or burned. However, to assure total combustion of the wood and, also, for purposes of temperature control, an additional supply of air is fed to the combustion chamber by secondary air source 14. It should also be mentioned that in order to initially fire up the wood fuel as it enters the combustion chamber, a certain amount of natural gas or propane needs to be supplied to the combustion chamber and this is accomplished by means of natural gas or propane service 15. These aspects of the system will, of course, be discussed in greater detail hereinbelow.

The products of combustion out of combustion chamber 12 are fed to blending chamber 13, to which are also fed certain gaseous emissions from the veneer or other wood materials being dried in dryer 16. More particularly, as was previously mentioned, when veneer or other wood products are dried, they give off gaseous materials that are combustible. It is these gaseous emissions that are fed back to the blending chamber, as shown in the figure, when they are mixed with the products of combustion out of the combustion chamber and then burned. This final product of combustion then flows into a separator unit 17 which functions to filter out incombustible impurities from the hot gaseous emerging from the blending chamber, thereby leaving the gases substantially free from these impurities.

A major portion of the hot gases out of the separator Unit is directed through a damper 18 to the dryer, the remainder of the gases passing into the atmosphere. The damper controls the amount of hot gases flowing to the dryer and is operated in response to the temperature signal applied to it via line 20, the damper thereby helping to maintain the proper temperature in the dryer. Also contributing to the temperature control of the system is a fuel metering signal that is developed in the separator unit and fed back to metered wood fuel source 10 via line 21. As its name implies, the fuel metering signal controls or meters the amount of wood fuel that is fed to burner 11 for combustion and, therefore, controls the quantity and the temperature of these hot gases.

It should finally be mentioned in connection with the FIG. 1 system that instead of venting all of the remaining hot gases to atmosphere, a portion'thereof may be used in heating up a boiler 22 to produce steam, as is illustrated in the figure. It should also be mentioned that whatever hot gases are ultimately vented into the atmosphere are substantially free of any polluting ingredients, which is an additional improvement over the prior art.

The FIG. 1 system is presented in greater detail in FIG. 2 to which reference is now made, the same numerical designations being used in FIG. 2 as were used in FIG. 1 wherever appropriate. As shown, the raw waste wood is fed by means of a high pressure air line 23 to a cyclone and rotary feeder mechanism 24. The high pressure in the line forces the waste wood toward the system and a blower (not shown) is used at the far or input end of the line to supply the needed air pressure. The cyclone and rotary feeder mechanism performs the dual function of retrieving the air or, stated differently, of separating the air from the wood, and of then feeding the wood to a shaker screen apparatus 25. Cyclone and rotary feeder mechanism 24 is a standard piece of equipment frequently used in the lumber field and, therefore, its construction, operation and use is well known to those skilled in the art. Accordingly, suffice it to say that as the air and wood enter mechanism 24, the rotary feeder therein seals off the air and thereby prevents it from continuing with the wood to the shaker screen apparatus. The air that is thusly separated out is funnelled up through the center of the cyclone portion or member of mechanism 24 and out into line 26 which directs the air to a rotary feeder 27.

In shaker screen 25, the raw waste wood is first shaken out to separate the finer wood material from the coarser pieces. In so doing, the fine particles of wood are discharged onto rotary feeder 27 where they are again mixed with the air coming from line 26 to be pneumatically conveyed to another cyclone and rotary feeder mechanism 28. As for the coarser pieces and chunks of wood in shaker screen 25, these are conveyed by a screw conveyor device 30 to a pulverator 31 which, as its name implies, literally hammers or pulverizes the wood into finer pieces. After pulverization, the reduced wood is conveyed back to the shaker screen unit by a second screw conveyor 32 where the process is repeated, that is to say, the wood is shaken out with the finer particles passing through the screen and thereafter conveyed to rotary feeder 27, whereas the still coarse pieces of wood are returned to the pulverator for further size reduction. This process is repeated until all of the raw wood is ultimately reduced to a relatively fine particle size and passed to rotary feeder 27. It should be mentioned at this point that shaker screen 25, as well as pulverator 31 and screw conveyors 30 and 32, are all well known in the art and, therefore, no further description of them is deemed necessary here.

As was previously mentioned, the air in pressure line 26 picks up the fine particles of wood in rotary feeder 27 and conveys them to cyclone and rotary feeder mechanism 28 which functions in the same manner as cyclone and rotary feeder mechanism 24. Accordingly, mechanism 28 separates the air from the fine particles of wood which then pass into a large storage bin, the air continuing down the pressure line designated 34. The particles of wood stored in bin 33 constitute the wood fuel mentioned in the earlier description of FIG. 1. Coupled to the storage bin is an endless chain type of device 35 that scoops up the wood in the bottom of the bin and conveys it to a feeder device 36 that is metered to provide the right amount of said wood fuel to burner ll. More specifically, the particles of wood feed to the feeder device are forced down duct 37 by the highpressure air coming from line 34, a fan 38 helping the process by pulling the air and the wood toward the burner. The metering mechanism in feeder device 36 may be a motor-driven damper or any one of a number of other commerically available mechanisms that can be adapted for use herein. In any event, the metering mechanism acts acts in response to a signal from controls unit 40 to either reduce or increase the amount of wood fuel permitted to enter duct 37 according to the needs of the system. Of course, any wood fuel conveyed to feeder device 36 but which does not enter duct 37 is returned to storage bin 33.

The wood fuel is finely divided and, therefore, is held in suspension by the air as it moves or flows down ducts or pipes 37 and 41 toward burner 11. The fuel and combustion air are introduced into combustion chamber 12 in such a way that a vortex flow is established therein to aid in the process of combustion, additional or secondary combustion air being supplied to the combustion chamber by means of fan 42 and pipe 43 for the reasons previously mentioned. As was also mentioned earlier, a natural gas or propane source is provided as a pilot light, for pre-heating purposes, and as a standby auxiliary fuel source. The products of combustion out of chamber 12 are passed to blending chamber 13 to which are also fed the gas emissions originating in dryer 16. These emissions are fed to the blending chamber via duct 44, a dryer vent return air fan 45 being used to aid in this process by sucking the fumes from the dryer and feeding them directly into the blending chamber.

The final products of combustion coming from the blending chamber are then fed to separator 17 via a refractory lined duct 46 referred to as a blendalator, the function of the blendalator being to provide a transitional stage between the burner and the separator. Any combustion of the wood fuel and the emissions still remaining to be completed takes place in the blendalator, so that the blendalator insures that the process of combustion is fully completed before the product thereof is fed into the separator. Separator 17, as mentioned earlier in connection with FIG. 1, separates or filters out the various uncombustible impurities that are part of the product of combustion and which may be of microscopic size, such as particles of iron and silica, with the result that the hot gases emerging from the separator are substantially pure. A portion of these hot gases are then fed to dryer l6 and this is done via a duct47, the remainder of the hot gases being vented into the atmosphere through a stack 48 in which is located a damper mechanism for use in controlling the amount of hot gas to be vented and, therefore, the amount to be channeled to the dryer.

Referring once again to controls unit 40, a thermocouple sensing element is located in dryer 16 and this thermocouple device feeds a temperature signal to the control unit which, in response thereto, and by means of a pneumatic signal, operates the damper in stack 48 to vary the amount of hot gas flowing to the dryer according to its needs. Similarly, a thermocouple sensing element is also located in separator l7 and this thermocouple device likewise sends a temperature signal to the control unit. In turn, the control unit applies an electrical signal to the metering mechanism in feeder device 36, the metering mechanism, in response thereto, operating to increase or decrease the amount of wood fuel out of the feeder device and, therefore, the amount of wood fuel fed to the burner. Less wood fuel will ultimately bring down the temperature of the gases flowing from the separator to the dryer, more wood fuel having the opposite effect of course. Accordingly, by means of the signals and the control apparatus mentioned, both the temperature .and the volume of the gases entering the dryer can be monitored.

The construction of a burner according to the present invention is shown in detail in FIGS. 3, 4, 5 and 5(a) and, as shown therein, burner 11 is a two-stage structure in which combustion chamber 12 constitutes the first stage and blending chamber 13 the second stage. The burner is cylindrically-shaped and generally symetrical about its center line, the two chambers being lined with a refractory material, such as high alumina firebrick 50 lining the combustion chamber and castable fireclay 51 around the blending chamber.

At the input to the combustion chamber is a product deflector unit, generally designated 52, comprising a burner tube 53 that is coupled at its input end to burner fan 38 and at its output end to the chamber 54 in which the combustion of the wood fuel is initiated. As may be seen from the figures, particularly FIGS. 5 and 5(a), the burner tube is cylindrically-shaped and has a series of dispersion vanes 55 mounted peripherally around the inside of the tube near its input end, the dispersion vanes being positioned at such an angle that the combustion of combustion air and wood fuel held in suspension therein is deflected into a counterclockwise movement or rotation as it flows by the dispersion vanes into the burner tube. One angle that has been found to be suitable for said purpose is the angle of 45 as formed by the plane of each vane and the center line of the burner tube. As previously mentioned, dispersion vanes 55 are located at the input end of the burner tube.

At the output end of the burner tube and extending partially into chamber 54 is deflector apparatus, generally designated 56, that comprises a nosecone section 57 at its forward end and a conical deflector section 58 at its rearward end, the two conical sections being separated by a pair of concentric pipe sections 60 and 61 respectively used for housing and support purposes. Mounted within pipe 60 and abutting against nose-cone section 57 is a support base 62, a bolt 63 extending through this support base and the nosecone section as shown in FIG. 5. A jamb nut 64 is tightly wound on the bolt so as to firmly or rigidly hold the nosecone section in place between the support base and the nut. The entire deflector apparatus is rigidly held in position with the aid of support brackets 65 which are mounted between pipe 60 and the wall of burner tube 53, and is best shown in FIG. 5. Thus, brackets 65 centrally fix the position of pipes 60 and 61 inside the burner tube and the pipes, in turn, aid in holding cone sections 57 and 58 in position. A backing plate 66 is mounted on and covers the base of conical section 58, the junction between the plate and the conical section being filled in to form an annular concave-shaped fillet 67 that pro vides s smooth transition from the surface of the conical section to that of the plate. As will be pointed out below, fillet 67 plays an important role in the process of deflecting the wood fuel product as it passes through the burner tube on the way to the combustion chamber. Finally, completing the deflector apparatus, is a deflector ring 68 that is held in position by the wall of burner tube 53 at the junction of conical section 58 and pipe 60, the ring being tapered or angled along its inside surface 68a so as to deflect gases and wood fuel passing through it toward conical section 58.

The entrance to combustion chamber 54 includes an entrance port 70 through which product deflector unit 52 extends toward the combustion chamber and at the input end of which there is mounted a gas ring burner 71. The gas ring burner is illustrated in both FIGS. 3 and 4 and, as shown therein, is hollow, has openings or orifices 71a along its entire circular inner surface or periphery, and, by means of pipe 7 lb, is connected to natural gas or propane source 15. As may also be seen from the figures, particularly FIG. 4, the opening or passageway through the center of gas burner ring 71, the opening being designated 710, is approximately the same size or diameter as that of entrance port 70 to which it is adjacent. Accordingly, any gases flowing through ring opening 710 thereafter flow smoothly into entrance port 70. The significance of gas burner ring 71 will be pointed out hereinbelow.

As previously mentioned, chamber 54 is enclosed by a wall of firebrick 50. However, between the firebrick and the outer wall of burner 11, which is also the outer wall of combustion chamber 12, the said outer wall being designated 11a, is a passageway 72 that is connected to combustion air fan 42 by means of duct 43. Thus, in combustion chamber 12, in a concentric arrangement, is chamber 54, firebrick wall 50, passageway 72 and outer burner wall 11. As has already been intimated if not indicated in prior discussions, air provided by air fan 42 flows through passageway 72 in the direction of the arrows therein and thereafter passes through gas burner ring 71 and entrance port 70 into chamber 54. In addition to combustion air being supplied in this manner, that is to say, through the input end of chamber 54, air is also supplied directly to the chamber by means of channels or passageways through firebrick wall 50, that interconnects chamber 54 with passageway 72, there being several such channels through the wall located at different points therealong both axially and circumferentially. The channels shown in FIG. 3 are designated 73 and they are arranged in a sortof helical path around the wall of the chamber so as to produce a helical vortex type of flow pattern having a counterclockwise movement or rotation.

Finally, completing the construction of combustion chamber 12 is an exit port 74 located, as its name implies, at the output end of chamber 54. Exit port 74 leads to blending chamber 13 and the products of combustion leaving chamber 54 pass through port 74 on their way to the blending chamber.

Blending chamber 13 is similar to combustion chamber 12 in several respects in that it also includes a chamber 75 formed by a wall of refractory material 51 and with entrance and exit ports 76 and 77, respectively, at its input and output ends. The blending chamber and what goes on inside it constitutes the second stage of burner 11 and, in this regard, it is therefore coupled to the combustion chamber by means of entrance port 76 which, as the figure illustrates, is in communications with exit port 74. Coupled to this second stage is return vent fan 45 which, as previously indicated, feeds the combustible gases fromthe dryer to chamber 75.

Considering now the operation of burner 11 and of chambers 12 and 13 therein, air under pressure with wood fuel in suspension therein is fed first to product deflect unit 52 where it is forced by dispersion vanes 55 into a counterclockwise rotation. In view of the forward motion of the air and wood fuel, the counterclockwise rotation produces a helical flow pattern as the air and wood fuel flow down burner tube 53. In this regard, the wood is finely ground at this point and may be introduced into the burner at speeds of approximately 5,000 feet per minute, which is just a bit less than miles per hour. Accordingly, the air and wood enter and travel down the burner tube at a fairly high speed. With respect to the size of the wood particles, these will vary in size, of course, but the maximum diameter of these particles will be in the order of five sixteenths of an inch. It should also be mentioned that among other things, dispersion vanes 55 cause the wood fuel to become evenly dispersed in the air that carries them so as to provide a uniform cross-sectional wood particle density.

The air and wood fuel combination moves down burner tube 53 in the aforementioned manner until it reaches nose cone section 57 where the center portion of this mass of air and wood is deflected outwardly and forced to pass through the space between pipe 61 and the burner tube wall. However, it should be emphasized that the air and wood continues to turn in a counterclockwise direction as it moves forward through this space. When the air and wood reaches deflector ring 68, the outermost portion of it impinges upon deflecting surface 680 which forces it downwardly where, together with the other air and wood passing through this space, it impinges upon the forward part of conical section 58. The air and wood particles, still in a counterclockwise rotational movement, move along or follow the surface of the conical section until they reach backing plate 66 and fillet 67 where the entire mass of air and wood fuel is smoothly channeled or turned outwardly toward wall 50 in chamber 54. In the proximity of the inner surface of the wall or upon contact with the wall itself, the wood particles are ignited due to the high temperature at the walls surface, which temperature may be in the range between 2,2002,400 F. Upon ignition, the wood particles are deflected by the wall of chamber 54 and they then move into and through the chamber as they continue and complete the combustion process. During this period of time, the wood continues to move in a helical path toward exit port 74.

It will be recognized from what has already been said that as the air and particles of wood suspended in it emerge from the burner tube to impinge upon conical section 58, they are joined by a mass of secondary air introduced, as previously mentioned, via passageway 72. Secondary air is also introduced directly into the chamber via channels 73, as was also previously mentioned. This secondary air serves a dual purpose, namely, it insures or guarantees that the wood fuel has sufiicient air for complete combustion and, therefore, total comsumption although the amount of primary or conveying air is adjusted and maintained to meet this requirement and, second, it helps to control the temperature within the combustion chamber to within the desired limits. Accordingly, this secondary air plays an important role in the combustion stage of the operation. It should finally be mentioned that gas burner ring 71 is used for start up purposes, that is to say, to bring the temperature of the combustion chamber to ignition range and that the natural or propane gas fed to the ring may be used to supplement the wood as a fuel should that be needed.

The products of combustion obtained in combustion chamber 12 pass through ports 74 and 76 into blending chamber 13 where, in chamber 75, these products of combustion are mixed with the combustible emissions coming from dryer 16. It should be mentioned at this point that while a portion of the wood fuel is consumed in the combustion chamber, another portion continues to burn as it enters chamber 75. Accordingly, the dryers fumes or emissions are ignited in the blending chamber and burn with the remaining wood fuel, the resultant output from the blending chamber going through exit port 77 and into blendalator 46 where any combustion of the wood fuel and the emissions still remaining to be completed takes place. Thus, the blendalator is a transitional member that insures that the process of combustion is fully completed before the products thereof are fed into separator unit 117. It would be worthwhile to mention at this point that chamber 75 is larger than chamber 54 and, therefore, that the products of combustion expand as they enter chamber 75. It should further be mentioned that the heat generated in chamber 54 due to the burning of the wood fuel there is more intense than the heat generated in chamber 75. The overall effect, therefore, is that the temperature of chamber 75 is maintained between l,200- l ,600" F 800-l ,000 cooler than chamber 54. As in the blending chamber, the temperature in blendalator 46 will range between l,200-l ,600 F., as will the final products of combustion passing through the blendalator on their way to the separator.

Separator unit 17 is illustrated in detail in FIGS. 6 and 6(0) and, as shown therein, is shaped like a tank that includes a tank wall 80 lined along 'its inside surface with refractory brick 81. The floor of the separator is also lined with this protective refractory brick. On the floor of the separator is mounted a box 82 that extends from about the center of the floor to the separator wall. The box is completely enclosed except for an opening 820 through its top wall, at that end of the box that is at the center of the separator floor, and a door 821) at its extremity near the separator wall. As will be seen later, uncombustible and other foreign particles enter box 82 through its opening 82a and the accumulation of this matter is later removed from the box through door 8212. Located at the top of the separator, at the center of its roof, is an outlet duct 83. This duct is cylindrically-shaped, extends through the roof of the separator and for a short distance downwardly into the separator, and is open at its top and bottom. As will also be seen later, the clean hot gas that is vented to atmosphere and also channelled to the dryer exits from the separator through this duct 83.

Surrounding outlet duct 83 are a plurality of directional louvres 84 that are mounted between top sup porting plates 85 and a bottom support member 86. As is indicated by the names given them, plates 85 and member 86 sandwich the louvres in between them and hold the louvres rigidly in place, As is shown in FIG. 6(a), the louvres are arranged in a circular pattern with the forward end of one louvre being parallel to and spaced from the rearward end of the next adjacent lou vre. Stated differently, the louvres are arranged so that air circulating on the outside of them will be forced to pass between them to the space inside of them.

Mounted between support member 86 and opening 82a in box 82 is a truncated conical section 87 that is coupled and held to member 86 by means of several support brackets 88 extending from the wall of the separator. The conical section is open at both ends, the narrow end, which is the lower end, being superimposed on opening 82a so that any particulate matter falling or dropping down on the inside of the conical section will thereby enter the box. In this regard, it should be mentioned that another, much smaller, cone 89 is located and mounted at the bottom end of conical section 87 so that the two together resemble the letter W in the alphabet. Cone 89 is held to cone 87 by means of bars 9 0 shown in FIG. 6(a) and as is also shown therein, the two conical sections form an annular or ring-shaped opening between them through which the abovesaid particulate matter passes to box 82. The apex or top of cone 89 is closed.

Several other features should be mentioned at this time before the operation of the separator is described. First, the final products of combustion are fed to the separator by means of duct member 46 which is a con tinuation of the blendalator and, therefore, is similarly designated. The opening to the separator is hidden by member 46 and is not illustrated in FlGS. 6 and 6(a) for sake of clarity. Such an opening through the wall of the separator can surely be visualized by anyone skilled in the art. Second, the space between the wall of the separator and conical section 87 has been designated 91 and it is into this space, which acts like an expansion chamber, that the products of combustion are fed. Third and last, the space between the wall of the separator and louvres 84 have been designated 92, the space within the louvres being designated 93.

Considering now the operation of separator unit 17, the hot gas entering the separator enters space 91 at a fairly high speed and enters in such a manner as to move in a counterclockwise direction around conical section 87. Because hot gases normally rise and, furthermore, because of the pressure behind it, the gas entering the separator moves up along conical section 87 in chamber 91, all the while rotating in a counterclockwise direction as it does so. Accordingly, the path followed by the gas is a helical one.

It will be noticed from FIG. 6 that as the gas rises it is confined to an ever narrower space, which the result that a Venturi effect is produced and by the time it has reached space 92 the gas speed has increased and it is whirling around in a counterclockwise direction on the outskirts of louvres 84. The gas is ultimately forced at some point in its rotation to pass between the louvres and enter space 93 on the inside of the louvres where it continues to move in a counterclockwise direction. Thissame gas, which previously rose, now moves down through space 93 and into the hollow of conical section 87, where it continues to rotate but in an ever more confined space as it approaches the bottom or lower end of the conical section. Ultimately, the gas bottoms out, at which point it rises in a column at the center of conical section 87 and then exits or vents through outlet duct 83. Thus, within the conical section, we have a hot gas moving downwardly in a helical path along its inner surface and a column of this gas rising at its center. It will be recognized by those skilled in the art that cone 89 and the configuration formed by ill it aids in the transition from the outer column of gas to the inner or center column of gas. The hot gas going through outlet duct 83, as previously mentioned is either channelled to the dryer or vented to the atmosphere.

The primary function of the separator unit is to separate out various kinds of uncombustible inorganic matter, such as particles of iron, silica, and the like, and this is done in the hollow of conical section 87 by the centrifuge action produced there. The particles collect, more or less, along the inner surface of the cone and fall or slide along it through opening 82a into box 82. The box is, of course, periodically emptied of these accumulations through door 82b.

Although a particular arrangement of the invention has been illustrated and described above by way of example, it is not intended that the invention be limited thereto. One modification, for example, is illustrated in HO. 7 where the heat generated by the burner is primarily intended for a boiler and only secondarily for a dryer. Accordingly, in the FIG. 7 arrangement, the products of combustion out of blending chamber are first fed to boiler 22 where a portion of the heat energy is used for the generation of steam. Thereafter the operatio n is maame as alreadydesc ribed, namelyfto separator unit 17 and after the separator either to a dryer 16 or to atmosphere. Accordingly, the invention should be considered to include any and all modifications, alterations or equivalent arrangements falling within the scope of the annexed claims.

Having thus described the invention, what is claimed is:

l. A system useful in the lumber mill industry for burning the waste woodobtained from the processing of lumber and the combustible fumes emitted from the lumber when it is dried in a dryer, said system thereby constituting an additional source of heat energy and effectively combatting pollution of the atmosphere, said system comprising: apparatus for comminuting the waste wood to produce a dry powdery wood fuel; a burner having first and second chambers to which said wood fuel and the fumes are respectively fed, said burner including first means for combusting said wood fuel in said first chamber, second means for passing the products of said combustion to said second chamber wherein it mixes with the fumes fed thereto, and third means for combusting said mixture in said second chamber; a separator coupled to receive the products of combustion out of said second chamber, said separator including means that causes said products of combustion to move in such a manner as to produce a centrifuge action that is effective to separate out impurities therefrom, whereby a hot output gas that is substantially free of polluting ingredients is produced, said separator including additional means to channel a portion of said output gas to the dryer to dry the lumber therein and to vent the remainder thereof to atmosphere; fourth means for suspending said wood fuel in a stream of air and for feeding said air-suspended wood fuel to said first chamber; and fifth means for sucking the fumes out from the dryer and feeding them to said second chamber.

2. The system defined in claim 1 wherein said apparatus includes a high-pressure air line for transporting the raw waste wood; a first cyclone and rotary feeder mechanism coupled to said air line, said cyclone and rotary feeder mechanism including first means for separating the air from the wood, and second means for thereafter feeding the wood to a shaker screen mechanism; a shaker screen mechanism for separating the fine particles of wood from the coarser pieces, said shaker screen mechanism including third means for discharging said fine wood particles into said air line for pneumatic conveyance to a second cyclone and rotary feeder mechanism, and fourth means for conveying said coarse pieces of wood to a pulverator; a pulverator for comminuting said coarse pieces of wood to produce fine particles thereof, said pulverator including fifth means for conveying said fine particles of wood back to said shaker screen mechanism which, in turn, discharges them by means of said third means into said air line for conveyance to said second cyclone and rotary feeder mechanism; a second cyclone and rotary feeder mechanism including sixth means for separating the air from said fine particles of wood, and seventh means for thereafter discharging said fine particles of wood into a storage bin; and a storage bin wherein said fine particles of wood are stored before being fed as wood fuel to said burner.

3. The system defined in claim 1 wherein said burner includes a deflector unit coupled at its input end to said air line and storage bin to receive wood fuel suspended in air therefrom and coupled at its output end to said first chamber, said deflector unit including a plurality of dispersion vanes mounted at its input end and positioned at such an angle as to cause said air and wood fuel to move in a counterclockwise manner as it flows therethrough toward the output end of said deflector unit, and including deflector apparatus mounted at its output end to deflect said air and wood fuel outwardly toward the outer walls of said first chamber.

4. The system defined in claim 1 wherein said means in said separator includes a hollow and truncated conical section that is open at its apex and base, said conical section being mounted inside said separator with its apex vertically beneath its base, a plurality of louvres mounted in a circular manner above the base of said conical section, and an outlet duct mounted substantially at the center of said louvre arrangement and extending through the roof of said separator, said duct being open at its two ends; said separator including input apparatus by means of which the products of combustion out of said second chamber are directed in a counterclockwise movement around the apex of said conical section and upwards therealong.

5. The system defined in claim 1 wherein said apparatus includes a high-pressure air line for transporting the raw waste wood; a first cyclone and rotary feeder mechanism coupled to said air line, said cyclone and rotary feeder mechanism including first means for separating the air from the wood, and second means for thereafter feeding the wood to a shaker screen mechanism; a shaker screen mechanism for separating the fine particles of wood from the coarser pieces, said shaker screen mechanism including third means for discharging said fine wood particles into said air line for pneumatic conveyance to a second cyclone and rotary feeder mechanism, and fourth means for conveying said coarse pieces of wood to a pulverator; a pulverator for comminuting said coarse pieces of wood to produce fine particles thereof, said pulverator including fifth means for conveying said fine particles of wood back to said shaker screen mechanism which, in turn, discharges them by means of said third means into said air line for conveyance to said second cyclone and rotary feeder mechanism; a second cyclone and rotary feeder mechanism including sixth means for separating the air from said fine particles of wood, and seventh means for thereafter discharging said fine particles of wood into a storage bin; and a storage bin wherein said fine parti cles of wood are stored before being fed as wood fuel to said burner; and wherein said burner includes a deflector unit coupled at its input end to said air line and storage bin to receive wood fuel suspended in air therefrom and coupled at its output end to said first chamber, said deflector unit including a plurality of dispersion vanes mounted at its input end and positioned at such an angle as to cause said air and wood fuel to move in a counterclockwise manner as it flows therethrough toward the output end of said deflector unit, and including deflector apparatus mounted at its output end to deflect said air and wood fuel outwardly toward the outer walls of said first chamber.

6. The system defined in claim 1 wherein said apparatus includes a high-pressure air line for transporting the raw waste wood; a first cyclone and rotary feeder mechanism coupled to said air line, said cyclone and rotary feeder mechanism coupled to said air line, said cyclone and rotary feeder mechanism including first means for separating the air from the wood, and second means for thereafter feeding the wood to a shaker screen mechanism; a shaker screen mechanism for separating the fine particles of wood from the coarser pieces, said shaker screen mechanism including third means for discharging said fine wood particles into said air line for pneumatic conveyance to a second cyclone and rotary feeder mechanism, and fourth means for' conveying said coarse pieces of wood to a pulverator; a pulverator for comminuting said coarse pieces of wood to produce fine particles thereof, said pulverator including fifth means for conveying said fine particles of wood back to said shaker screen mechanism which, in turn, discharges them by means of said third means into said air line for conveyance to said second cyclone and rotary feeder mechanism; a second cyclone and rotary feeder mechanism including sixth means for separating the air from said fine particles of wood, and seventh means for thereafter discharging said fine particles of wood into a storage bin; and a storage bin wherein said fine particles of wood are stored before being fed as wood fuel to said burner; and wherein said means in said separator includes a hollow and truncated conical section that is open at its apex and base, said conical section being mounted inside said separator with its apex vertically beneath its base, a plurality of louvres mounted in a circular manner above the base of said conical section, and an outlet duct mounted substantially at the center of said louvre arrangement and extending through the roof of said separator, said duct being open at its two ends; said separator including input apparatus by means of which the products of combustion out of said second chamber are directed in a counterclockwise movement around the apex of said conical section and upwards therealong.

7. The system defined in claim 1 wherein said burner includes a deflector unit coupled at its input end to said air line and storage bin to receive wood fuel suspended in air therefrom and coupled at its output end to said first chamber, said deflector unit including a plurality of dispersion vanes mounted at its input end and positioned at such an angle as to cause said air and wood fuel to move in a counterclockwise manner as it flows therethrough toward the output end of said deflector unit, and including deflector apparatus mounted at its output end to deflect said air and wood fuel outwardly toward the outer walls of said first chamber; and wherein said means in said separator includes a hollow and truncated conical section that is open at its apex and base, said conical section being mounted inside said separator with its apex vertically beneath its base, a plurality of louvres mounted in a circular manner above the base of said conical section, and an outlet duct mounted substantially at the center of said louvre arrangement and extending through the roof of said separator, said duct being open at its two ends; said separator including input apparatus by means of which the products of combustion out of said second chamber are directed in a counterclockwise movement around the apex of said conical section and upwards therealong.

8. The system defined in claim 1 wherein said apparatus includes a high-pressure air line for transporting the raw waste wood; a first cyclone and rotary feeder mechanism coupled to said air line, said cyclone and rotary feeder mechanism including first means for separating the air from the wood, and second means for thereafter feeding the wood to a shaker screen mechanism; a shaker screen mechanism for separating the fine particles of wood from the coarser pieces, said shaker screen mechanism including third means for discharging said fine wood particles into said air line for pneumatic conveyance to a second cyclone and rotary feeder mechanism, and fourth means for conveying said coarse pieces of wood to a pulverator; a pulverator for comminuting said coarse pieces of wood to produce fine particles thereof, said pulverator including fifth means for conveying said fine particles of wood back to said shaker screen mechanism which, in turn, discharges them by means of said third means into said air line for conveyance to said second cyclone and rotary feeder mechanism; a second cyclone and rotary feeder mechanism including sixth means for separating the air from said fine particles of wood, and seventh means for thereafter discharging said fine particles of wood into a storage bin; and a storage bin wherein said fine particles of wood are stored before being fed as wood fuel to said burner; and wherein said burner includes a deflector unit coupled at its input end to said air line and storage bin to receive wood fuel suspended in air therefrom and coupled at its output end to said first chamber, said deflector unit including a plurality of dispersion vanes mounted at its input end and positioned at such an angle'as to cause said air and wood fuel to move in a counterclockwise manner as it flows therethrough toward the output end of said deflector unit, and including deflector apparatus mounted at its output end to deflect said air and wood fuel outwardly toward the outer walls of said first chamber; and wherein said means in said separator includes a hollow and truncated conical section that is open at its apex and base, said conical section being mounted inside said separator with its apex vertically beneath its base, a plurality of louvres mounted in a circular manner above the base of said conical section, and an outlet duct mounted substantially at the center of said louvre arrangement and extending through the roof of said separator, said duct being open at its two ends; said separator including input apparatus by means of which the products of combustion out of said second chamber are directed in a counterclockwise movement around the apex of said conical section and upwards therealong.

9. The system defined in claim 1 wherein said system further includes a first network for metering the amount of wood fuel fed to said burner in accordance with the temperature conditions in said separator, said first network including a first heat-sensitive device mounted in said separator for monitoring the temperature therein, said first device being operable in response to said temperature conditions to produce a first signal corresponding thereto, and a second device included in said fourth means for metering the amount of wood fuel fed to said first chamber in response to said first signal; and wherein said system further includes a second network for metering the amount of hot gas fed to the dryer in accordance with the temperature conditions therein, said second network including a second heat-sensitive device mounted in the dryer for monitoring the temperature therein, said second device being operable in response to said temperature conditions to produce a second signal corresponding thereto, and a damper device mounted between the dryer and said separator, said damper device being operable in response to said second signal to meter the amount of hot gas flowing from said separator to the dryer in accordance with the temperature conditions therein.

ill. The system defined in claim 1 wherein said apparatus includes a high-pressure air line for transporting the raw waste wood; a first cyclone and rotary feeder mechanism coupled to said air line, said cyclone and rotary feeder mechanism including first means for separating the air from the wood, and second means for thereafter feeding the wood to a shaker screen mechanism; a shaker screen mechanism for separating the fine particles of wood from the coarser pieces, said shaker screen mechanism including third means for discharging said fine wood particles into said air line for pneumatic conveyance to a second cyclone and rotary feeder mechanism, and fourth means for conveying said coarse pieces of wood to a pulverator; a pulverator for comminuting said coarse pieces of wood to produce fine particles thereof, said pulverator including fifth means for conveying said fine particles of wood back to said shaker screen mechanism which, in turn, discharges them by means of said third means into said air line for conveyance to said second cyclone and rotary feeder mechanism; a second cyclone and rotary feeder mechanism including sixth means for separating the air from said fine particles of wood, and seventh means for thereafter discharging said fine particles of wood into a storage bin; and a storage bin wherein said fine particles of wood are stored before being fed as wood fuel to said burner; and wherein said burner includes a deflector unit coupled at its input end to said air line and storage bin to receive wood fuel suspended in air therefrom and coupled at its output end to said first cham her, said deflector unit including a plurality of dispersion vanes mounted at its input end and positioned at such an angle as to cause said air and wood fuel to move in a counterclockwise manner as it flows therethrough toward the output end of said deflector unit, and including deflector apparatus mounted at its output end to deflect said air and wood fuel outwardly toward the outer walls of said first chamber; and wherein said means in said separator includes a hollow and truncated conical section that is open at its apex and base, said conical section being mounted inside said separator with its apex vertically beneath its base, a plurality of louvres mounted in a circular manner above the base of said conical section, and an outlet duct mounted substantially at the center of said louvre arrangement and extending through the roof of said separator, said duct being open at its two ends; said separator including input apparatus by means of which the products of combustion out of said second chamber are directed in a counterclockwise movement around the apex of said conical section and upwards therealong; and wherein said system further includes a first network for metering the amount of wood fuel fed to said burner in accordance with the temperature conditions in said separator, said first network including a first heat-sensitive device mounted in said separator for monitoring the temperature therein, said first device being operable in response to said temperature conditions to produce a first signal corresponding thereto, and a second device included in said fourth means for metering the amount of wood fuel fed to said first chamber in response to said first signal; and wherein said system further includes a second network for metering the amount of hot gas fed to the dryer in accordance with the temperature conditions therein, said second network including a second heat-sensitive device mounted in the dryer for monitoring the temperature therein, said second device being operable in response to said temperature conditions to produce a second signal corresponding thereto, and a damper device mounted between the dryer and said separator, said damper device being operable in response to said second signal to meter the amount of hot gas flowing from said separator to the dryer in accordance with the temperature conditions therein.

11. The system defined in claim 3 wherein said deflector apparatus includes first and second conical sections at its forward and rearward ends, respectively, the base of said rearward conical section including structure to smoothly divert said air-suspended wood fuel radially outwardly toward the walls of said first chamher; and wherein said deflector apparatus further includes a deflector ring whose inside surface is angled to deflect any air-suspended wood fuel coming into contact with it toward said rearward conical section.

12. The system defined in claim 3 wherein said burner further includes a supplementary air supply arrangement to provide additional air for combustion in said first chamber, said arrangement including a plurality of orifices through the wall of said first chamber and located in a generally helical path therealong, and a channel extending outside the wall of said first chamber and leading to the input end thereof, the air flowing through said orifices moving in a counterclockwise direction in said first chamber.

13. The system defined in claim 3 wherein said burner further includes a supplementary air supply arrangement to provide additional air for combustion in said first chamber, said arrangement including a plurality of orifices through the wall of said first chamber and located in a generally helical path therealong, and a channel extending outside the wall of said first chamber and leading to the input end thereof, the air flowing through said orifices moving in a counterclockwise direction in said first chamber; and wherein said deflector apparatus includes first and second conical sections at its forward and rearward ends, respectively, the base of said rearward conical section including structure to smoothly divert said air-suspended wood fuel radially outwardly toward the walls of said first chamber; and wherein said deflector apparatus further includes a deflector ring whose inside surfact is angled to deflect any air-suspended wood fuel coming into contact with it toward said rearward conical section.

14. The system defined in claim 4 wherein said separator includes a box that is coupled through an opening therein to the apex of said conical section, said separator further including structural means to cause the entering hot gases to flow around and up along said conical section in a counterclockwise direction and at an ever-increasing speed, through said louvres and down into the hollow of said conical section to produce a centrifuge action therein that separates out incombustible ingredients mixed with the hot gases, said ingredients falling through the apex of said conical section into said box.

15. The system defined in claim 11 wherein said separator includes a box that is coupled through an opening therein to the apex of said conical section, said separator further including structural means to cause the entering hot gases to flow around and up along said conical section in a counterclockwise direction and at an ever-increasing speed, through said louvres and down into the hollow of said conical section to produce a centrifuge action therein that separates out incombustible ingredients mexed with the hot gases, said ingredients falling through the apex of said conical section into said box.

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Classifications
U.S. Classification110/186, 110/220, 110/216, 110/102, 110/233, 55/397, 110/222
International ClassificationF23C6/00, F23J15/02, F23G5/32, F23G7/10, F23G7/06, F23G7/00, F23C6/04
Cooperative ClassificationF23G7/105, F23G5/32, F23J15/027
European ClassificationF23G5/32, F23J15/02D3, F23G7/10A
Legal Events
DateCodeEventDescription
May 17, 1982AS10Assignment of 1/2 of assignors interest
Owner name: BAARDSON, ANDREW B.
Effective date: 19811230
Owner name: ROBBINS, E.H. EUGENE, OREGON
May 17, 1982AS02Assignment of assignor's interest
Owner name: BAARDSON, ANDREW B.,
Effective date: 19750603
Owner name: BUTTS, ROBERT, TRUSTEE FOR MILL CONVERSION CONTRAC
May 17, 1982ASAssignment
Owner name: BAARDSON, ANDREW B.,
Free format text: ASSIGNMENT OF ASSIGNORS INTEREST.;ASSIGNOR:BUTTS, ROBERT, TRUSTEE FOR MILL CONVERSION CONTRACTOR. INC., BANKRUPT.;REEL/FRAME:003991/0390
Effective date: 19750603
Owner name: ROBBINS, E.H. EUGENE, OREGON
Free format text: ASSIGNMENT OF 1/2 OF ASSIGNORS INTEREST;ASSIGNOR:BAARDSON, ANDREW B.;REEL/FRAME:003991/0395
Effective date: 19811230