US1971895A - Process of reclaiming bone black and like materials - Google Patents

Description

Au 28, 1934. N. R; ANDREWS 1,971,895

PROCESS OF RECLAIIING BONE BLACK AND LIKE MATERIALS Filed April 24. 1933 {Sheets-Sheet 1 INVENTOR v NATHAILE L R DREWS Aug. 28, 1934. ANDREWS 1,971,895

PROCESS or" RECLAIMING BONE BLACK AND LIKE MATERIALS Filed April 24', 1933 2 Sheets-Sheet 2 INVENTOR NATHAN I EL ATTORNEY Patented Aug. 28, 1934 PATENT OFFICE PROCESS OF RECLAIMING BONE BLACK AND LIKE MATERIALS Nathaniel R. Andrews, Yonkers, N. Y.

Application April 24, 1933, Serial No. 667,723

Claims.

This invention relates to a new and improved process of reclaiming or reconditioning bone black or animal charcoal, a material commonly known in the sugar refining and allied arts as 5 char.

' Char is a material generally used for filtering and decolorizing sugar, glucose and like substances.

One of the objects of the invention is toprovide a new and improved process of the above character that can be carried out more economically than it has been possible to do in processes hitherto practiced.

Another object of the invention is to provide a new and improved process whereby boiler furnace gases may be most effectively utilized in reclaiming and reconditioning char. Another object of the invention is to provide a process whereby danger of overheating or of burning the char during the reconditioning or reclaiming process is entirely eliminated.

Another object of the invention is to provide a new and improved process of the above character which may be carried on substantially automatically.

More particularly, my new and improved process for reconditioning or reclaiming char contemplates the use of the boiler furnace gases of a sugar refinery, utilizing the air which is preheated in the cooling of the reconditioned char in the boiler furnace, utilizing the heat produced by the combustion in the reconditioning of the char to heat the boiler feed water, and controlling the rate of processing or reconditioning of the char, so that the char reconditioning or reclaiming process becomes, in effect, an ec'onomizer for the boiler, breathing" with the boiler so that the heat reclaimed from the furnace gases is proportional to the rate of fuel burning in the boiler furnace and therefore also proportional to the rate at which the sugar is processed.

It is, of course, well known that the steam generated in a sugar refinery is employed almost exclusively in the processing of the sugar; for example, in the evaporating pans, etc. Any steam used for heating of the building or for other nonsugar uses is usually exhaust steam from one or more of the sugar processing operations. It is therefore clear that, if the char processing is controlled in such manner as to be proportional to the steam demand or to the fuel consumed in the boiler room of a refinery, it is also substantially proportional to the rate of sugar processing, which in turn is proportional to the demand .55 for the char employed during the processing. 1

have found that a control based in this manner is convenient, effective, inexpensive and labor saving.

Other objects and aims of the invention more or less specific than those referred to above will 60 be in part obvious and in part pointed out in the course of the following description of the steps and the relation of each step to one or more of the others thereof employed in carrying out my process, and the scope of protection contemplated will be indicated in the appended claims.

Before proceeding to a descriptionof my new and improved process and a preferred form of apparatus illustrated for carrying out the same, it may first be noted that the process hereinafter described relates particularly tothe reconditioning or reclaiming of bone char in the sugar refining industry. However, the process herein described is not limited particularly to the sugar 76 refining industry. It also applies to the reconditioning or reclaiming of char used in the refining of glucose. The process may also be applied to materials other than char, which term, as above described, includes animal charcoal, bone 80 black or like substances.

In the process of sugar refining the exhausted char comes from the char filters containing from fifteen (15%) percent to twenty (20%) percent of moisture.

In processing or treating this char for re-use for refining purposes, or revivifying it, as the process is commonly called, this moisture must be driven oif, the char raised to such a temperature that the foreign matter absorbed, adsorbed or otherwise removed by the char from the sugar solution with which it has come in contact must be distilled or burned off and out of the char structure and the char then cooled to a temperature suitable for re-use in the char filters.

Since it is essential in carrying out my improved process that the char processed shall enter and leave the apparatus employed to carry out the process at sensibly the same temperature and since a considerable amount of heat is generated by the combustion of the foreign material which is being eliminated from the char, if the heat present in the steam and the vapors driven from the char in the process of cooling thereof can be reclaimed. it is apparent that aside from the loss of heat from radiation from the apparatus employed in' carrying out the process, no heat or practically no heat will have been lost in carrying out the process.

My improved process, therefore, contemplates the reclaiming or revivifying of char by drying, burning or cooling it in such a manner by use of gases from the gas passages of .the boiler furnace that the revivifying or reconditioning process acts as a heat saver or economizer in the boiler plant, it being an important object of my invention that the char being processed is in amount proportional to thefuel burning rate or steam demand upon the boiler plant. In other words, I contem plate the utilization of the boiler furnace gases in such a manner that the process breathes in unison with the boiler, conserving the heat in the vapors driven from the char in processing the same and in burning the foreign matter present therein, conserving and reclaiming the heat liberated by the char in cooling the same after processing, and utilizing the said heat all or in part, in heating the boiler feed water, and utilizing said heat liberated by cooling the char, in the preheat-, ing of the air used in the boilerfurnace combustion process.

It will be apparent that great care must be exercised to insure that temperature and air conditions are such that a minimum damage will result to the char structure itself. 7

In carrying out my improved process, I solve this problem by the utilization of gases from the boiler furnace gas passages at two or more temperature levels, one level being that of the ordinary exitga's, and the other, a higher temperature level the temperature of the higher temperature gas being maintained constant, regardless of the quantity required (of course, within the limits of the apparatus) and'by the control of the air supply to the char for the purpose of combustion in burning out the material collected by the char from the sugar solution. The higher temperature level gas is selected at a zone in the gas passages of the boiler furnace so located that at the normal rating of the boiler furnace the temperature of the gases from that zone is that which will be required to bring the char to the desired maximum temperature for processing, but no hotter. As the rating of the boiler is increased and the gas at this zone becomes hotter, the temperature thereof as it enters the processing chamber will be maintained constant by dilution with gases taken from the lower temperature zone, namely the ordinary exit gases from the boiler furnace, the volume or rate of fiow of the resultant mixed gases being controlled automatically by the temperature of the char being processed so as to maintain the char at the desired optimum temperature required for processing.

This zoning of the boiler furnace gases by the use of a bleeder" type of boiler setting furnishes protection to the char in process in that the greater part of the work of drying and heating is done by gasesof comparatively low temperatures, only enough of the higher temperature level gases being utilized in the mixture to raise the char to the optimum temperature required for the proper processing of the latter, the amount of heat furnished the char by the boiler furnace gases being controlled by the temperature of the char itself, as above mentioned. In order that the heat of the boiler gases may be utilized to best advantage, as the rating of the boiler changes due to variation in steam demand on it by the refinery, the rate of processing of the char must vary in proportion to the rate of fuel burning.

In my improved process, I attain this end by controlling the rate of draw or flow of char from the apparatus and by controlling the amount of air admitted to the char directly from the control equipment which regulates, in proportion to the steam demand, the rate of fuel burning in the boiler furnace itself.

I also provide a safe-guard feature so that if for any reason, internally or externally, the temperature of the char rises appreciably above the maximum desired temperature, athermostatic control device actuated by the temperature of the char in process will reduce or entirely arrest the admission of air to the char by reducing or reversing the draft in the vapor chamber, in which the upper ends of the char process tubes are fixed, and by reducing the pressure in or entirely arresting the flow of air into the pressure chamber in which the lower ends of the char processing tubes terminate. These steps of the process not only in an extreme case stop the supply of air to the char, but the steam and products of combustion, since they can escape less easily in that direction, will force themselves further down in the char process tubes, thus effectively'blanketing the over-heated char with steam or gases that will not support combustion.

In this way, the char structure itself is prevented from being destroyed by combustion.

Having thus briefly outlined a number of the essential features of my improved process, I shall now proceed to a more detailed description of the process, utilizing in this description a preferred form of apparatus I contemplate employing in carrying out my invention.

In the accompanying drawings forming a part of this specification, and wherein similar reference characters refer to similar parts throughout the several views of the drawings, Figure 1 is a schematic view showing an improved form of apparatus for carrying out my improved process, and

Figure 2 is a similar view in perspective of one part of the apparatus.

Referring to these drawings, the char to be processed flows or is discharged from the char filter 1, through a hopper 2, onto the belt conveyor 3, said belt conveyor discharging the char into the boot of the bucket elevator 4. This bucket elevator 4 discharges the char into the upper end of the feed hopper 5. The screw conveyor 6, forming its own trough in the char distributes the latter evenly in the feed hopper 5, any excess of said char spilling into the chute through the pipe 7, whence it falls into the boot of the elevator 4.

The reference numeral 8 denotes a feed plate at vthe lower end of the chute 5 of the hopper 5.

This feedplate 8, which may be adjustable, is adapted to regulate the amount of char being delivered from the chute 5 onto an inclined tube sheet 9.

The reference numerals 10 a. b. c. designate what may be termed char feed tubes, said tubes having their upper ends expanded or otherwise fixed into apertures formed in the inclined tube sheet 9. The char. flows downwardly through the feed tubes 10 a. b. 0. into the process tubes,

11 a. b. 0., which process tubes have their upper ends expanded into or otherwise fixed in the tube sheet 12. The process tubes 11 a. bac. extend downwardly through a tube sheet 13, a baffle plate 14, and the tube sheet 15.

The process tubes 11 a. b. c. are preferably expanded into or otherwise snugly fitted in aper-' tures provided in the tubes sheets 13 and 15, and the baffle plate 1.4.

The reference numeral 16 denotes what may be termed the char draw consisting of a stationary plate having slots or holes 1'7 a. b. 0. provided thereon, and movable bars 18 a. b. 0., only one of which is shown herein, raised upon the stationary plate 16. These bars 18 a. b. 0. have fixed thereon and at right angles thereto the bars 19 a. b. c.

The movable bars 18 a. b. c. are given a reciprocal motion by means of the char draw drive consisting of the connecting rod 20, connected to said movable bars and actuated by a crank pin 21, provided upon a disk 22, revolving about the center 23, said disk being driven by any suitable means, such as the stoker mechanism.

It will be seen that (Figure 1) because of the reciprocating motion given the bars 18 a b. c. and consequently to the bars 19 a. b. c., the char is pushed from side to side, causing it to flow intermittently through the slots 17 a. b. c., provided in the stationary plate 16.

These slots 17 a. b. c. in the plate 16 are so located with respect to the bars. 19 a. b. c. that when the latter are centrally disposed under the lower ends of the process tubes, 11 a. b. c., the angle of repose of the char is such that the reconditioned char cannot flow through the slots or holes 17 a. b. c.

It will, therefore, be seen that the rate at which the char is allowed to escape from the process tubes 11 a. b. c. or is drawn therefrom, is controlled by the rate of reciprocation of the bars 19 a. b. c., operated as above described, from the disk 22. In other words, the speed of rotation of the disk 22 determines the amount of discharge of the char from the process tubes through the apertures of the plate 16.

The I char after passing through the char draw falls into ,the hopper 23, from which it flows on to the conveyor belt 24, which in turn discharges it into the hopper 25, whence it passes through trap 26, out of the apparatus.

It will be obvious that while I refer to feed tubes as 10 a. b. c., and similarly to the other cooperating parts of the apparatus, there is provided a large bank of these tubes and their corresponding cooperating parts depending upon the capacity of the apparatus employed to carry out the process. mean that any desired number of the instrumentalities referred to by the prefix number may be provided.

Figure 2 of the drawings shows the manner in which these feed tubes and their cooperating instrumentality may be banked within the enclosing casing 43.

The reference numeral 27 denotes the furnace, the gases of combustion from which pass up vertically through thene'st of boiler tubes 28 a. b. c., and may pass-out of the furnace over the top of the baffle 29, between the baffles 29 and 30, between the baflles 31 and 32, and out of the boiler gas passages into the flue 33, or said g2 ses of com-,

bustion may pass over the top of the banle 30, under the lower edge of the baflie 34, and then out of the boiler into the flue 35, or only a portion of the combustion gases may pass out of the boiler simultaneously at each of the above described routes.

The flue 36 connects the flues 33 and 35, and a damper 3'7 is provided in the flue 35, a damper 38 in the flue 33, and a chmk damper 39, provided with an arm or lever 40 and a weight 41, closing against stop 42, is provided in the flue 36. Damper 39 is so counterbalanced that in free air or free gases it just closes against stop 42, but is The reference letters a. b. c.

free to swing downwardly thus connecting, under certain conditions, flues 33 and 35.

The gases flow from flues 33 and 35 into the enclosure'formed by the tube sheets 12 and 13 and the casing 43, passing upwardly around the process tubes 11 a. b. c., and into the flue 44, thence through exhaust fan 45, and up the chinmey or stack 46, to the atmosphere.

As already stated, the char comes from the char filters containing from fifteen (15) to twenty (20) percent of moisture. This moisture, of course, must be driven from the char before the latter can be heated to such a temperature as will permit the burning or distillation of the solid impurities of the char.

It is also an important object of my invention to conserve as much of the heat energy of the boiler furnace gases as it is possible to do. This is accomplished by utilizing as fully as possible the furnace gases at their normal exit temperature level, using only enough of the higher temperature furnace gases as is necessary properly to process thechar. The char, of course falls by gravity through the process tubes 11 a. b. c. in accordance with the operation of the char draw.

I therefore provide the flue 35 so that furnace gases at their normal exit temperature level may be conducted directly into the upper part of the heating chamber formed by the casing and the tube sheets 12 and 13. These gases conducted through the flue 35 are sufliciently high in temperature to drive out all or the major part of the moisture and the more volatile constituents of the char before the latter has reached the higher temperature zone of the heating chamber to which the higher temperature gases are conducted by the flue 33.

The gases at their normal exit temperature level are, therefore, discharged into the heating chamber at a location considerably above the point where the higher temperature gases enter said chamber.

Only enough of the furnace gases at their normal exit temperature level passes through the flue 36 and past the check damper 52 as is necessary to temper or cool the higher temperatured furnace gases so that the resultant mixture of the higher and lower temperature gases will be of a temperature suificiently high to cause such combustion of the foreign matter in the char at the point where these higher temperatured gases enter as is necessary properly to process the same after the moisture of a large part thereof, has been driven from the char by the lower temperature gases entering the heating chamber through the flue 35. Free air is drawn into the blower 47, and forced through the flue 48, into the closed pressure or discharge chamber 48 the top wall of which is formed by the tube sheet 15. Air passes into the process tubes 11 a. b. 0. through the spaces between the particles of char at the lower end 01' the process tubes, 11 a. b. c.

The products of combustion formed by burning ofi materials subtracted from the sugar solution by the char distillates, and the steam driven from the char pass out from the upper ends of the process tubes 11 a. b. 0. into an enclosed vapor chamber, the top and bottom walls of which are formed by the tube sheets 9 and 12 respectively.

From this vapor chamber the steam and vapors from the process tubes 11 a. b. c. mingle with some air which is drawn through the char in the feed tubes 10 a. b. 0., pass through the flue 49, into the surface condenser or heat exchanger 50, and

exhaust fan 45, being discharged into the atmosphere by the stack or chimney 46. A damper 52 is provided in the flue 49. Condensate from the condenser 50 flows out through the pipe 75, and is trapped from the apparatus by means of the trap 76.

Free air passes into the flue 53, through the spaces provided between the process tubes 11 a. b. 0. under the bafiie plate 14, into the flue 54', and in reverse direction, directly over baflle 14, and under the tube sheet 13, thence to flue 55, through the blower 56 into the air chamber 5'7, from whence it passes into the furnace 4'1 through the fuel bed 58. Thus the air utilized to cool the reconditioned char is preheated and discharged into the boiler furnace.

The boiler feed water entering through the pipe 59 flows through the surface condenser or heat exchanger 50, passes by way of pipe 60, into the boiler drum 61. Thus the heat of the steam and vapors generated by burning out the foreign matter present inthe char is conserved by preheating the boiler water.

For purposes of this description of my improved process, I assumethat the boiler and the furnace are equipped with a combustion control which proportions the rate of fuel feed to the steam demands upon the boiler.

It is also assumed that-the elevator 4, and the conveyor 6, are driven continuously at a constant rate.

The belt conveyor 3, by means of which the char to be processed is delivered into the boot of the elevator 4, is driven by the motor 62, as shown,

which is controlled as to stopping and starting by the swinging targets 63 and 64 a. b. 0., located in the feed hopper chute 5 Target 63 is located at the end of the feed hopper chute 5 furthest from the discharge of elevator 4. Targets 64 a. b. 0., only one of which is shown, extend along the lower portion of the feed chute 5 -These targets normally hang by gravity in vertical positions, but, as indicated, are pushed aside by the char in the hopper and its chute. Both targets are provided with the lever 65, and the armatures 66, which -mal e electrical connections at the positions shown, these energizing coils which throw motor control contactors, not'shown, in or out, thereby stopping or starting the motor 62, which drives the conveyor 3.

The construction is such that any one of the targets 64 a. b. c. may start the motor 62. That is to say, the strength of the starting coil energized by the targets 64 a. b. c. is suflicient to overcome the strength of the stopping coil controlled by the target 63 so that the motor 62 will start when any of the targets 64 a. b. c. are vertical regardless of the target 63. V i

From the foregoing, it.- will be seen that this automatically operating mechanism insures that a uniform supply of char to be processed will, at all times, be maintained upon the surface of the tube sheet 9. v

The char draw is controlled from the fuel feed apparatus by any suitable means (not shown).

As already stated, one of the objects of the invention is to proportion the processing of the char to the fuel consumed in the boiler furnace. In order to accomplish this end in a very simple manner, the disk 22 which reciprocates the bars 18 a. b. 0., may be driven through an operative connection with the stoker drive or with the powdered fuel pulverizer in the event that such fuel is employed. I have shown schematically at 22 a means for driving the disk 22.

thence into the flue 51, into flue 44, through the i The amount of air admitted through the flue 48, into the pressure chamber 48 and consequently into the char process tubes 11 a. b. c., is also controlled-from the fuel feed apparatus by varying .the speed of the blower 47, whereby the air pressure in the pressure chamber will be varied in proportion to the rate of fuel consumed in the boiler furnace.

The blower 56 and the exhauster 45 are controlled by the boiler combustion control means in the usual manner. This control mechanism for the blower 56 and the exhauster 45 is not shown in the drawings inasmuch as this mechanism is common in the boiler furnace art.

A thermostatic control consisting in part of a thermo-couple, the hot junction of which is inserted in the char in one of the process tubes 11 a. b. c. at the point 68, operates damper 38 to admit gas from the high temperature zone in a quantity sufficient, when tempered or cooled with gas from the low temperature zone of the boiler furnace, to raise and maintain the temperature of the char in process tubes 11 a. b. c. to the desired degree.

A temperature control consisting 01 a thermocouple having its hot junction inserted in flue 33 at 67 operates to adjust damper 37 in flue 35 so that sufficient gas will flow from flue 35 through flue 36, past counter-balanced check damper 39, into flue 33, to maintain the temperature of gas at the point 67 at a constant desired temperature. Since. the temperature of these gases is held constant at the point 6'7, it is the volume rather than the temperature of these gases which is controlled in order to maintain the char at the point 68 at a constant temperature. flow of gases through damper 38 is followed by a correspondingly increased flow past the check 39.

The check damper 39 prevents any flow of gas from flue 33 to flue 35.

The damper 52 in the flue 49 is operated thermostatically from the point 69, by means of a thermo-couple having its hot junction inserted in the char in one of the process tubes 11 a. b. c., in such a manner that if for any reason the char temperature in the process tubes rises above a certain fixed degree, the damper 52 will close and will not again open until the temperature of the char has fallen to the desired safe processing temperature.

Damper 48*is controlled in the samemanner and if desired, niay be mechanically connected to the damper 52; 1

Thus it will be seen that when the temperature of the char in the process tubes 11 a'. b. c. rises to such a point that the char structure might be damaged by combustion, automatic control initiated by the thermo-couple at the point 69 in one of the tubes 11 a. b. c. closes the damper 52, and through the closing of the damper 52, the damper 48 is closed. This provides for a blanketing or extinguisher action in the process tubes.

Inasmuch as the steam and vapors are unable to escape through flue 49, their easiest course of travel will be downwardly through the process Any increased are covered with heat insulating material. Moreover, the relative position of the feed tubes and the process tubes is made such that the char does tubes, very little of the incoming char is exposed to the steam rising from the process tubes.

It will, therefore, be seen that I have provided a process of revivifying or reconditioning char well adapted to attain, among others, all the ends and objects above pointed out in a very simple manner.

By the zoning of the gases in the passages of the boiler furnace, thus providing a bleeder type furnace, that is to say, by using gases at one or more temperature levels, one of which may be the normal exit gas temperature and the other or others at successively higher temperature levels, I am able by mixing of the lower temperature gas with the gas of higher temperature to gain and maintain a desired temperature somwhere between the two or more temperatures without regard (within certain limits, of course) to the amount of gas required at the said desired temperature for processing,

It will also be seen that I am able to use the air employed in the cooling of the char in the case the temperature of the char being processed rises above a fixed point in the process tubes, and am also able so to regulate the char feeding equipment whereby condensation, which would tend to bridge the char and thus prevent its free entry into the process tubes, is avoided. Another advantage of my process is that the char is treated in vertical, stationary tubes of comparatively small diameters in such a manner that the char entering each tube is dried, burned and cooled in said tube which is continuous from end to end, the char being exposed to such oxydizing agent, air or gas in the tube as is admitted at the lower end and moved upwardly through the tube, this air supply being automatically proportioned to the amount of char being processed.

Another and most important end obtained by means of my process is the manner of controlling the amount of char'being-processed, orthe rate of flow of char into the process tubes as well as the amount of air admitted, from the rate of fuel burned in the boiler furnace so that the char processing apparatus breathes with the boiler or is proportional to the steam demand upon the boiler or to the fuel consumed whereby the heating of the feed water'and the preheating of the air entering the boiler furnace makes this process a true fuel economizer complete in itself for the boiler.

There is obviously a complete combination or cooperation between the boiler furnace and the char processing equipment. As stated previously the steam demand or rate of fuel consumed by the boiler of a sugar refinery is roughly proportional to the rate of sugar processing and hence to the demand for char. As the sugar processing increases in a refinery more-steam is used in the evaporating pans etc.', this produces (through the boiler combustion control mechanism) an automatic increase in the fuel consumed in the boiler'; i. e. the automatic stoking mechanism speeds up. More air is then required for the furnace and this is supplied automatically by the control attached to blower 56. The control disc 22 operating the char draw automatically speeds up, delivering more reconditioned char. There is a demand for additional fiue gases to heat up the process tubes more rapidly and this increase is produced automatically by the increased feed of fuel and air to the boiler furnace. There is also a demand for more conditioning air to pass upwardly through the processing tubes. This is supplied by the increased pressure produced in the char discharge chamber by the automatic speeding up of blower 4'7. There is also an increased demand for the preheating of the boiler feed water and this is supplied by the additional .vapors rising through the process tubes which deliver their heat to the boiler feed water in the feed heater 50. Each element of the equipment therefore depends in a peculiar manner upon the operation of the remaining elements.

As 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 105 in a limiting sense.

Itis also to be understood that the language used in the following claims is intended to cover all of the generic and specific features of the in-,

vention herein described, and all statements of derived from a boiler furnace and automatically 1% controlling the rate .of passage of said char through said zone in proportion to the rate at which fuel is fed to the said boiler furnace.

2. The process of claim 1 wherein air is passed through said processing zone in countercurrent to said char and at a rate automatically proportioned to the passage of said char through said zone.

3.'The process of claim 1 including the step of cooling the reconditioned char by passing combustion air for said furnace in heat transfer relationship therewith.

4. The process of claim 1 including the steps of passing air through said processing zone and of cooling reconditioned char by combustion air, the rates of passing air through said processing zone and of cooling said reconditioned char being controlled in proportion to the rate at which fuel is fed to the said boiler furnace.

5. The process of claim 1 wherein the constricted processing zone is maintained in a vertical position.

6. The process of claim 1 wherein the flue gases are abstracted from said boiler furnace at at least two temperature levels.

'I. The process of claim 1 wherein the flue gases are abstracted from said boiler furnace at at least two temperature levels; one of said temperatures being higher than that required for processing 0 the char and another being the normal exit temperature of the flue gases from said furnace.

8. The process of claim 1 wherein the flue gases are abstracted from said boiler furnace at at least two temperature levels; one of said temperatures being higher than that required for processing the char and another being the normal exit temperature of the flue gases from said furnace and wherein these flue gases are mixed and are maintained at a constant temperature prior to heating said processing zone.

9. The process of claim 1 including the steps of cooling reconditioned char by passing air in heat transfer relationship therewith and then passing said'air through said processing zone.

10. In the reconditioning of char and the like by heating, the process which comprises establishing and maintaining a constant temperature flue gas mixture and passing said mixture in heat transfer relationship with char to be "reconditioned at a rate controlled to produce a. constant char temperature.

11. In the reconditioning of char and the like, the process which comprises passing flue gases from a boiler furnace in indirect heat transfer relationship with char to be processed, passing air through the char heated in this manner, collect ing vapors evolved from the char and passing them in heat transfer relationship with boiler feed water, the rate of char processing being automatically controlled by the rate of stoking of the said boiler furnace.

12. In the reconditioning of char and the like, the process which comprises passing char downwardly through a feeding zone and then through a reconditioning zone, the said reconditioning zone being heated by flue gases from a boiler furnace, passing conditioning air upwardly through said reconditioning zone and downwardly through said feeding zone, collecting the gases and vapors evolved from said zones and passing this mixture in heat transfer relationship with boiler feed water, the rate of char processing being controlled in proportion to the rate of stoking of said boiler furnace.

13. The process of claim 12 wherein conditioning air is passed in heat transfer relationship with reconditioned char prior to passing it through said processing zone.

14. In the reconditioning of char and the like by heating, the process which comprises passing char to be reconditioned through a constricted processing zone, heating said zone by flue gases derived from a boiler furnace, passing conditioning gases through said processing zone in countercurrent to said char and at a rate proportional to the rate of stoking of said boiler furnace and automatically stopping the supply of said con-'- ditioning gases upon the temperature of the char reaching a dangerous point.

15. In the reconditioning of char and the like by heating, the process which comprises passing char to be reconditioned through a constricted processing zone, heating said zone by flue gases derived from a boiler furnace, passing conditioning gases through said processing zone in countercurrent to said char and at a rate proportional to the rate of stoking of said boiler furnace and automatically reversing the passage of said conditioning gases upon the temperature of the char reaching a dangerous point.

NATHANIEL R. ANDREWS.

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