US3376202A - Waste converter - Google Patents

Description

H. E. MESCHER WASTE CONVERTER April 2, 1968 4 Sheets-Sheet 1 Filed Oct. 8, 1964 INVENTOR HAROLD E. MESCHER BY $048 M ATTORNEY April 1968 H. E. MESCHER 3,376,202

WASTE CONVERTER Filed Oct. 8, 1964 4 Sheets-Sheet 2 INVENTOR HAROLD E. MESCHER ATTORNEY H. E. MESCIHER WASTE CONVERTER April 2, 1968 4 Sheets-$heet 5 Filed Oct. 8, 1964 INVENTORV HAROLD EQMESCHER BY fx 5. M

ATTORNEY April 2, 1968 E. MESCHER WASTE CONVERTER 4 Sheets-Sheet 4 Filed Oct. 8, 1964 R E H u m E m m M. M E Q. w 0 6 m N L T 0 MA R A f H 2 Y 4 9 B 2 M 4- 3 l wlll 4 7 2 x 3 36 3 I n||B| L.) [5w ||1|, O 1 4 E Hm M N 9 4 3 .J 5 G El Patented Apr. 2, 1968 Ere 3,376,202 WASTE CONVERTER Harold E. Mescher, Pico Rivera, Calif., assignor to Pacific Scientific Company, San Francisco, Calif, a corporation of California Filed Oct. 8, 1964, Ser. No. 402,512 4 Claims. ((31. 2G2-90) This invention relates generally to waste converters as of the Lantz type used for continuously producing charcoal and gas products from Waste or other materials such as wood, paper, grain hulls, etc., and the invention has reference more particularly to novel improvements in such converters.

Waste converters as heretofore constructed generally use rotating pressure seals at the ends of a heating retort for retaining the relatively high pressure gases generated during the operation of the converter. Such seals, as heretofore used, tend to leak, resulting in the escape of high pressure gas, which is not only dangerous and wasteful, but produces condensed tar products around the outside of the seals, which is highly objectionable. Also, in these converters as heretofore made, it has been necessary to prevent leakage at both the loading and discharge ends of the converters, and this is seemingly difiicult to accomplish satisfactorily.

The principal object of the present invention is to provide a novel improved converter which is designed to prevent the leakage of gases from the converter, thereby preventing air pollution, possible explosions, and the deposition of tars at points of leakage.

Another object of the invention is to provide a novel, improved converter wherein suction means is arranged for automatically withdrawing generated gases from the converter retort as rapidly as the same are produced, said converter being so constructed and arranged as to prevent leakage of generated gases through the loading and discharge ends of the retort.

A feature of the present invention is to provide a novel improved converter of the above character that is so designed that the retort pressure in the converter is substantially equal to or but slightly above atmospheric pressure, whereby the rotating end seals are no longer subject to appreciable pressure and it is relatively easy to prevent gas losses from the retort under all operating conditions.

Another feature of the present invention is to provide a novel improved converter of the above character employing a flare stack and responsive means for controlling the gas discharge blower of the converter whereby gases are withdrawn from the converter at a rate depending entirely upon the rate of production of such gases therein, the said removed gases being withdrawn for use in heating the converter retort or for other uses.

A still further feature of the present invention is to provide a novel converter of the above character wherein high pressure seal loading and unloading systems are eliminated, thereby greatly simplifying the structure of the converter.

These and other features and advantages of the present invention will be more apparent after a perusal of the following specification taken in connection with the accompanying drawings, wherein:

FIG. 1 is a partial vertical longitudinal sectional side view of a novel converter of the present invention;

FIG. 2 is a sectional view taken along line 22 of the structure shown in FIG. 1A;

FIG. 3 is a perspective view of this furnace taken from the rear; I

FIG. 4 is a schematic view similar to FIG. 3 showing the arrangement of the fuel piping;

FIG. 5 is a fragmentary enlarged view of the structure circled at Sin FIG. 1; and

FIG. 6 is a fragmentary enlarged view of the structure circled at 6 in FIG. 1A.

Similar characters of references are used in the above figures to designate corresponding parts.

Referring now to the drawings, the reference numeral 1 designates the insulated casing or housing of the converter, which casing is supported on a frame 2. Casing 1 is provided with propane or natural gas burners 92 (see FIG. 3) for producing =heat therewithin. Burners 92 are adapted to be supplied with propane or other gas from lines 3 during the initial start-up of the converter, and thereafter the casing 1 is heated with generated retort gas as will further appear, the temperature within insulated casing 1 being of the order of 1500 F. during operation.

A metallic cylindrical rotatable retort 4 is contained within the casing 1 and extends longitudinally thereof and has its ends projecting through conforming apertures in the ends of the casing. The end portions of retort 4 have support collars 5 and 5 fixed thereon, the circular periphery of which collars ride in grooves provides in supporting rollers 6 carried by yokes 7 and 7, yokes 7 being carried by a support frame 8 which in turn is supported by rollers 9, longitudinally movable on brackets 10 supported upon the frame 2. Yokes 7 are supported directly upon the frame 2. Rollers 9 permit thermal expansion and contraction of the retort 4 in use, the forward end of the retort moving in and out of the conforming aperture provided in easing 1 through which the retort extends. Frame 8 also supports the rear end of a closed conveyor housing 11 that has its forward portion supported upon a yoke 12 which in turn carries a support roller 13 riding on a stand 14. Within the conveyor housing 11 is contained a movable plate conveyor 15 driven by chain 16 that in turn is driven from a conveyor motor 17 through reduction gearing 18. The plate conveyor 15 receives carboniferous material such as wood chips, coal, sawdust, trash, etc., from a hopper 19 positioned near the forward end of the conveyor. The carboniferous material 20 feeds by gravity down the hopper 19, this hopper being supplied from a suitable source such as by use of a bucket conveyor 62. The height of the material 20 within the hopper 19 is maintained sufiicient so as to seal off the hopper and the closed conveyor housing 11 from the outside air to thereby seal off the cylindrical retort 4, which in use has an internal pressure very close to that of the atmosphere, so that it is not necessary to have a high pressure seal as such at the entrance to hopper 19, but the height of the material 20 within the hopper is sufiicient to provide an adequate seal since the retort does not contain an appreciable gas pressure in use.

Upper and lower bindicators 21 and 21, somewhat spaced apart, are mounted upon the hopper 19 and have cruciform vanes 22 projecting into the interior of the hopper, which vanes are rotated by motors within the bindicator housings through slip clutches. The vanes 22 of the bindicator 21 are normally above the level of material 20 in hopper 19 and so rot-ate continuously whereas vanes 22 of bindicator 21', being normally surrounded by material 20, do not rotate. Should vanes 22 of bindicator 21 stop rotating due to material 20 piling too high in hopper 19, the material conveyor motor will be stopped, since these bindicators are connected into the control circuit of the conveyor 62 supplying material 20 to the hopper. On the other hand, vanes 22 of the bindicator 21 are normally stationary and should these vanes rotate, a relay connected with bindicator 21 will operate to speed up the conveyor 6-2 supplying the hopper, so that the material is maintained at a level substantially as shown in FIG. 1 of the drawings, thus preventing access of outside air to the retort 4- and also preventing escape of gases from this retort through conveyor housing 11 and hopper '19 to the outside air.

A vibrating guide plate 23 is pivoted at 24 within the hopper 19 and cooperates with a lift drag plate 25 and the moving plates of conveyor to aid in moving the material onto the conveyor 15 in use. Lift drag plate is pivoted at 26 and as the conveyor plates move by, they agitate this drag plate and also the guide plate 23 to jar the carboniferous material onto the plate conveyor, while at the same time preventing the material from working its way down the conveyor housing 11 to bind the drive sprocket 27. A material feed plate or vane 28 is positioned within the hopper 19 so as to aid in guiding the material upon the conveyor and prevent the same from jamming against the rear wall of the hopper in use. Since the hopper 19 is sealed upon the casing of the conveyor housing 11 and as this housing is sealed at its upper end to the rotating retort 4, as will shortly appear, it will be noted that the intake to the retort is a sealed system. Although not capable of retaining or excluding high pressures, it retains retort operating pressures which are close to atmospheric pressure, so that no gases leak from the interior of the retort, nor do they leak into the retort through the material feed system just described.

The retort 4 is provided with an annular end plate 29 at its forward end, to the inner periphery of which is secured an entrance tube 30, into which the conveyor 15 discharges the carboniferous material to be treated, this material dropping onto a helical vane 31 positioned within the forward end portion of the retort 4, the vane 31 serving to catch the material from the conveyor and push it towards the rear of the retort, while the same rotates, as will further appear. In order to provide a low pressure seal between the rotatable retort 4 and the stationary conveyor housing 11 there is provided on the entrance tube 30 a bracket supported annular flexible disc 32 (FIGS. 1 and 5) which may be of stainless steel of light gauge such as 26 gauge, for example. The peripheral portion of this flexible disc 32 is secured between an annular notched plate 33, that is slidably supported on brackets 34 carried at regular angularly spaced points on the end plate 29, and a bearing ring 35 as of stainless steel that is secured by angularly spaced studs 36 having nuts 37 clamping plate 33 and ring 35 against flexible disc 32. A plate member 38 attached to the conveyor housing 11 carries a ring 35 to the outer portion of which is attached a bearing ring 40 as of brass which bears against the steel bearing ring 35.

Compression springs 41 surround the free ends of studs 36 and are confined therebetween and nuts 43 carried by studs 42 fixed to the annular end plate 29 of the retort. Springs 41 serve to press the bearing plate 35 against bearing ring 40, thereby providing a low pressure seal while permitting relative rotation of bearing plate 35 and bearing ring 40. The stationary ring 39 is provided with an annular cooling water space 44 through which cooling water can be circulated to prevent overheating of the bearing surfaces due to the heat within retort 4. The flexible disc 32 permits any slight misalignment or wobble of the rotating retort 4 in use with respect to the stationary conveyor housing 11.

The retort 4 is rotated by means of a retort drive motor 45 driving through reduction and chain speed gearing 46 and sprocket chain 47, idlers 48 and large sprocket 49, carried by support collar 5 fixed upon and surrounding the rear exposed end of the retort 4. The rear end portion of the retort 4 is sealed similarly to its forward end portion, the seal comprising a flexible disc 32' (see FIG. 6) similar to disc 32, having its inner portion attached to the retort 4 and its outer portion secured between an annular plate 50 and bearing ring 35 as of stainless steel through the intermediary of washer 51 by use of studs 36' threaded into ring 35' and having nuts 37 hearing on rotating retort 4 in use with respect to the stationary dis charge chute 52. Carrier brackets 63 attached to retort 4 protect flexible disc 32 against injury in use.

The retort 4 as shown in FIGS. 1 and 2 carries a series of mutually spaced interior longitudinally extending vanes.

53 which help to elevate the material 20 within the retort as this material advances rearwardly from helical vane 31 towards the rear of the retort. The vanes 53 are relatively shallow, but act to elevate the material in the retort as the material advances, so as to obtain uniform heating thereof. Since the retort is heated all around its circumference within the furnace casing 1, this heating action serves to rapidly drive out moisture from the advancing material, most of which moisture enters a central gas discharge tube 54 having its open forward end near the front of the retort. The retort. is also provided internally with a number of mutually spaced annular shallow dams 55 which serve to aid in retaining the material within the retort just sufficiently to insure the complete reduction to charcoal or other material within the retort and the elimination of gases and moisture therefrom. The drum retort 4 preferably tilts slightly towards its rear end to aid in moving the material from the forward end of the retort to the rear end, i.e., towards the discharge chute 52. This tilt may be of the order of to the running foot. The retention time of the material within the retort is primarily governed by the slope of the retort and the speed of revolution thereof, this speed being variable by varying the variable speed drive 46, for example, depending upon the nature of the material being treated.

By the time the material 20 reaches the discharge end of the retort 4, it has been turned into carbon and is discharged into chute 52 by gravity. This chute 52 is kept filled to a point somewhat above the bottom of the discharge end of the retort with discharged charcoal 20, so as to provide a seal between the retort and the lower screw conveyor 56, thereby preventing the entrance of air, which would cause the heated charcoal to burn. The level of the material 20' is maintained by bindicator 21', whose vanes are normally stationary, but if they should rotate, the output of the bindicator 21 acts upon the control circuit of the conveyor motor driving the screw conveyor 56 so as to cause this conveyor to slow down so as to maint tain the level of the charcoal as desired.

The central longitudinal extending gas discharge tube or conduit 54 is maintained under slight suction by means of a blower 57, whose inlet is connected to a plenum chamber 58 projecting inwardly from the rear end wall of chute 52. In practice, approximately all the steam and 50% or more of the combstible gas driven from the material 20 will enter the suction line of tube 54 near its forward end, thus aiding in preventing any smoke and gas from entering the conveyor housing 11, and this fluid will pass therealong to the rear of the retort, and after passing through blower 57, is discharged into a pipe 59, from whence it is conveyed to a scrubber 60 and from thence it passes into a storage tank 61 for distribution and use as desired.

In order to control the amount of gas withdrawn through discharge tube 54 so that the proper pressure is maintained within retort 4, a damper or butterfly valve 63 is contained within the discharge pipe 59. This valve is operated by a motor 64 operating through linkage 65, motor 64 being controlled in turn in accordance with the pressure and/ or temperature within the retort 4. To control this motor by temperature, a flare stack 66 may be employed, positioned above the discharge chute 52 and supplied with gas through a feeder flue 67. A pilot light 68 supplied with natural or propane gas is positioned beneath the open flare 66' of flare stack 66 so as to ignite gases leaving the top of the feeder flue 67, which flue contains a manually operable butterfly valve 69. Positioned upwardly within the stack 66 is located a temperature sensing bulb or thermostat 70 which is connected as by lead 72 into the control circuit of motor 64. As the pressure within the retort 4 gradually rises, the escaping gas from feeder flue 67 ignited by pilot light 68 will burn higher and higher within the stack 66, thereby raising the temperature of thermostat 70, which will in turn control motor 64 so that as the temperature rises, this motor will open butterfly valve 63 more and more, whereby more and more fluid will be drawn from the retort 4 to maintain the temperature therewithin substantially constant.

If desired, a pressure controller 71 can be used for controlling the motor 64, this pressure controller consisting of casing 73 having baffles 74 therewithin and provided with low and high pressure diaphragm switches 75 and 75', these switches serving to control motor 64 so that damper 63 is positioned to maintain a substantially constant pressure within retort 4.

During the initial start-up of the converter, the housing 1 is heated internally by the burners 92 supplied with propane or natural gas through line 3, as shown in FIG. 3. However, after the converter has been operating for a while and gas is being produced, the heating can be done by the gas so produced, and to accomplish this, produced gas lines or conduits 76 and '76, extending outwardly of discharge chute 52, have their inner ends projecting into the retort 4 and their open inclined inner ends are adapted to be closed by valve plates 77, pivoted at 78 and actuated by linkage 79, pivoted at 80. The shaft 80' of pivot 80 extends externally of chute 52 and is connected by linkage 81 to a motor 82. Motor 82 may be controlled manually or may be controlled automatically as by thermostat 70 or pressure controller 71. Thus, when the motor 82 is operated actuating linkages 81 and 79 the valves 77 are opened by moving the same to the position shown in dot dash lines in FIG. 1, whereupon gases within the retort pass outwardly through gas lines 76 and 76' and into the Venturi mixers 83 and 83 located at the front and at the rear of the converter (see FIG. 4) which mixers are supplied with air from a blower 84 passing air into lines 85 and 85, the mixed air and fuel gas then passing into front burners 86 and 86' and into rear burners 87 and 87. As specially shown in FIG. 2, these burners are hollow tubular members with longitudinally depressed burner portions 88 which are apertured to enable the mixture of air and fuel to pass into the interior of the casing 1, the ignition of which by pilot lights 89 serves to heat the retort 4.

In operation, the action of the converter is continuous, in that raw material is continuously fed into hopper 19 under control of bindicators 21 and 21', passes through conveyor housing 11 into the cylindrical retort 4, through which it passes slowly, the moisture and gases continued within the material being driven off. The majority of the steam and 50% or more of the combustible gases Will enter the gas discharge tube 54, the mouth of which is positioned near the front of the retort 4, where most evaportion of moisture takes place. A shield 90 is positioned in advance of the inlet of tube 54 and overlying the same, so as to prevent material from dropping down from the upper part of the retort and falling into the intake of this tube.

The gas leaving the rear end of the retort 4 and passing into gas furnace lines 76 and 76 is quite dry and burns readily within the burners 86, 86', 87, and 87', this action taking place after the converter has been operating sufiiciently to produce the desired gas output under the heating action of propane or natural gas burners 92, whereupon these burners 92 can be turned off and generated fuel used to heat the retort thereafter. The charcoal produced by the process, as heretofore pointed out, is discharged into screw conveyor 56 and stored for future use,

whereas the gas feeds out of discharge pipe 59 at a rate determined by the temperature and pressure within the retort as heretofore explained, which then passes into scrubber 60 and storage tank 61 for future use. Since the temperature and pressure Within the retort is controlled continuously by the action of thermostat 70 and/or pressure controller 71, no high internal pressure develops, and hence there is no undesired gas leakage at the retort end seals. Thus, it will be seen that the converter is entirely automatic in its operation and produces charcoal and gas by-products Which are used to heat the converter to maintain its operation or stored for future use or refinement. It will be noted that the sealed conveyor housing 11, the retort 4 and the discharge chute 52 form a closed, substantially inverted U- configuration which forms a sealed structure to prevent the escape of generated gases or inlet of unwanted air.

Since many changes could be made in the above construction and many apparently widely different embodiments of this invention could be made without departing from the scope thereof, it is intended that all matter contained in the above description or shown in the accompanying drawings shall be interpreted as illustrative and not in a limiting sense.

What is claimed is:

1. A material converter for continuously producing charcoal and gas products, comprising a casing containing a heated rotatable retort, means for supplying raw material such as wood chips, paper, grain hulls, etc., to said retort and removing charcoal material therefrom, means for sealing said retort, conduit means provided within said retort and extending exteriorly thereof for conducting combustible gases therefrom, the drier portion of said gases being used for heating said retort, said converter having valve means connected in said conduit means for controlling the flow of said gases through said conduit means, control means communicating with the interior of said retort and connected to said valve means for controlling the latter, whereby the gas pressure within said retort is retained substantially at atmospheric pressure during operation, a flare stack adjacent said retort connected for receiving gas therefrom, and means for igniting the gas in said flange stack, said control means comprising a temperature sensitive element within said flare stack connected for controlling the operation of said valve means.

2. A material converter as claimed in claim 1 wherein said control means comprises a pressure controller connected with the interior of said retort, said controller having pressure operated switches controlled by the gas pressure within said retort, and motor means controlled by said switches and connected for actuating said valve means.

3. A material converter for continuously producing charcoal and gas products, comprising a converter casing, a substantially horizontal cylindrical retort rotatable within said casing having input and output ends, means within said casing for heating said retort to a temperature of the order of 1500 R, an enclosed, inclined material supply conveyor housing having its upper end portion sealed to the input end of said retort and depending therefrom for delivering waste raw matreial such as wood chips, paper, grain hulls, etc., to said retort, a charcoal discharge chute having its upper end portion sealed to the output end of said retort and depending therefrom, said sealed material conveyor and sealed discharge chute serving to withstand substantially atmospheric pressure obtaining within said retort during operation of said converter, the lower end portion of said material conveyor housing and said charcoal discharge chute being selfsealed solely by the material passing therethrough, whereby gases generated within said retort cannot escape to the atmosphere nor can atmospheric air enter said retort during operation, a gas discharge conduit extending within said retort and having its input end positioned near the input end of said retort for conducting steam and moist combustible gases therefrom, valve means connected in said conduit for controlling the rate of flow of gas from said retort, and control means connected to said retort responsive to gas pressure thereWithin for controlling said valve means so as to maintain the interior of said retort at substantially atmospheric pressure in use.

4. A material converter as defined in claim 3 comprising an additional gas discharge conduit extending into the output end of said retort for removing dry gas therefrom for use in heating said retort, additional valve means connected to said additional discharge conduit for controlling the flow of gas therethrough, and motor 8 means :for actuating said additional valve means, said control means being connected for controlling said motor means.

References Cited UNITED STATES PATENTS 2,111,663 3/1938 Graemiger 21417.62' 1,945,530 2/1934 Karrick 2O2136 1,631,024 5/1927 Fisher 200-52 1,497,333 6/1924 Helbig 20115 10 2,973,306 2/1961 Chick et a1. 201l JAMES H. TAYMAN, JR., Primary Examiner.

Claims (1)

1. A MATERIAL CONVERTER FOR CONTINUOUSLY PRODUCING CHARCOAL AND GAS PRODUCTS, COMPRISING A CASING CONTAINING A HEATED ROTATABLE RETOR, MEANS FOR SUPPLYING RAW MATERIAL SUCH AS WOOD CHIPS, PAPER, GRAIN HULLS, ETC., TO SAID RETORT AND REMOVING CHARCOAL MATERIAL THEREFROM, MEANS FOR SEALING SAID RETOR, CONDUIT MEANS PROVIDED WITHIN SAID RETORT AND EXTENDING EXTERIORLY THEREOF FOR CONDUCTING COMBUSTIBLE GASES THEREFROM, THE DRIER PORTION OF SAID GASES BEING USED FOR HEATING SAID RETORT, SAID CONVERTER HAVING VALVE MEANS CONNECTED IN SAID CONDUIT MEANS FOR CONTROLLING THE FLOW OF SAID GASES THROUGH SAID CONDUIT MEANS, CONTROL MEANS COMMUNICATING WITH THE INTERIOR OF SAID RETORT AND CONNECTED TO SAID VALVE MEANS FOR CONTROLLING THE LATTER, WHEREBY THE GAS PRESSURE WITHIN SAID RETORT IS RETAINED SUBSTANTIALLY AT ATMOSPHERIC PRESSURE DURING OPERATION, A FLARE STACK ADJACENT SAID RETORT CONNECTED FOR RECEIVING GAS THERFROM, AND MEANS FOR IGNITING THE GAS IN SAID FLANGE STACK, SAID CONTROL MEANS COMPRISING A TEMPERATURE SENSITIVE ELEMENT WITHIN SAID FLARE STACK CONNECTED FOR CONTROLLING THE OPERATION OF SAID VALVE MEANS.

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