US1804593A - Apparatus and method for handling pulverized fuel - Google Patents

Description

May 12, 1931. ca. A...CONRATH 1,804,593

APPARATUS AND METHOD' FOR HANDLING PULVERIZE ID FUEL Filed May 10, 1926 I s Shgets-Sheet 1 May 12, 1931. G. A. CONRATH APPARATUS AND METHOD FOR HANDLING PULVERIZED FUEL Filed May 10, 1926 3 Sheets-Sheet 2 M m w m vs May 12, 1931. G. A. CONRATH 1,804,593

APPARATUS AND METHOD FOR HANDIDING PULVERIZED FUEL 3 Sheets-Sheet 5 Filed May 10, 1926 Patented May 12, 1931 UNITED STATES PATENT OFFICE GEORGE A. CONRATH, OF DES MOINES, IOWA, ASSIGNOR F ONE-HALF To CHARLES St DENMAN, OF DES MOINES, IOWA APPARATUS AND METHOD FOR HANDLING PULVER-IZED FUEL Application filed May 10,

5 in that form, it is possible to secure much higher thermal efiiciency on account of the more complete combustion. The usevof pul-' verized fuel permits great flexibility and reduces the standby and low banking losses.

One of the great problems in handling pulverized fuel arises from the ,cost of operation. 7

and maintenance. It is my purpose more particularly therefore to provide an apparatus and method whereby coal maybe fed to a pulverizer by a suitable feeder, together with a supply-of air,

which is preferably preheated. The coal is pulverized and when taken from the pulverizer'is separated or divided into the fine coal dust, which is conductedto the burner by air currents, and into the largerparticles, which are carried by air back to the pulverizer or muller. v 1

It is my purpose to provide in such a mechanism a simple, eflicient and durable structure, which can be manufactured and maintained economically.

In order to reduce the labor cost in handling coal and maintain efliciency in carrying out the entire process, it is desirable-that the various operations should he automatically controlled according to conditions in the furnace or the boiler.

It is therefore a further purpose of my present invention to provide means and a methodforautomatically controlling accord. ing to boiler pressure, for instance, the feed-.

ing mechanism, the air supply to the.coal

passing through the machine, the pulverizer, the coal separator means, and the supply of powdered coal to the combustion chamber.

1926. Serial in. 107,966.

iliary supply of air tothe furnace through the draft door. in cooperation and synchronism with the other automatic controls mention ed above. I further connect the control mechanism with a damper located for instance in the stack. I thus eliminate as far as may be the necessity for constant supervision and reduce the labor cost incident to the practice of the process in the use of the apparatus.

It is my object in connection with such a mechanism to provide novel features of mech.' anism for accomplishing the various purposes thus outlined.

' The feeder structure is shown in my copending application filed January 16, 1926, Serial No. 81,628.

With these and other objects in view, my invention'consists in the steps of the process hereinafter explained and in the construction, arrangement and combination of the various parts of my'apparatus, whereby the objects contemplated are attained, as hereinafter more fully set forth, pointed out in my claims, and illustrated in the accompanying drawings, in which:

1 Figure 1 is an elevation of an apparatus embodying my invention with which my method may be used. n

Figure 2 isa side elevation of the same apparatus, whereby my method may be practiced, some parts being shown in section and other parts being broken away.

Figure 3 is a plan view of the feeder, with parts omitted and parts shown in section taken on theline3-3 of Figure 2. A,

Figure 4 is a sectional view of'the feeder taken on the line 44.pf Figure 3; and

Figure 5 is a detail, sectionalview taken on the line 5-5 of Figure 2.

p In'the accompaning drawings, whereby I have illustrated an apparatus embodying my other source of supply and discharges it into the pulverizer or muller.

Referring to Figures 3 and 4, it may be noticed that the feeder 10 comprises a suitable casing 10a, in which is journaled a shaft 12,. whichprojects through one end wall of the feeder.

Fixed on the shaft 12 just below the fuel in-' take pipe 11 ,is a a feed wheel 13, which is formed with the radially projecting blades 14, between which are formed the fuel conducting pockets 15.

Just above the feed wheel 13 is a deflector plate 16 for directing the fuel into the pockets and preventing it from dropping into the air intake inlet hereinafter referred to.

The feeder casing 10a has at one side the air inlet portion 17 to which the heated air is supplied through a suitable pipe 18.

For controlling the supply of air to the feeder, I provide the throttle valve 19, having the stem 20 projecting to a point outside the air passage and having on its outer end the is transmitted to the shaft 12 through the gears 23 and 22.

It may be mentioned in this connection that ,a suitable clutch may be--provided for this P po I provide in connection with the feed wheel'- means for controlling the amount of fuel fed by the wheel to the pulverizer.

Mounted in the casing 10 and slidably arranged on the shaft 12 is a sliding sleeve drum member 26, having one end by the shaft 12, as at 27, and having the other end slotted as at 28, to snugly fit and "slide along the blades, 14. This sliding sleeve drum 26 is arranged to be slid longitudinally on the shaft 12 in such manner as to regulate the operating size of the pockets 15 by reducing or increasing their effective length.

The shaft 12 or a portion of its length is hollow and slidably receives an actuati rod 29, which is connected with the sliding s eeve drum 26 within the casing 10 by means of a pin 30, extending through a slot 31 in the wall ofthe' hollow portion of the shaft 12.

' The mechanism for controlling the rod 29 for thus adjusting the feeder will be hereafter referred to.

Pulvenlzer' 1 Fuel is. discharged from-the pockets 15 through a passage 32 at the lower part of the -49 and 50 and the belt 5 carried directly iiange 39 terminating in a downwardly openmg, raised, annular channel 40.

This whole device forms what may be called a supporting disc B forthe shaft 37 and the pulverizer or muller pan A.

Arranged in a circle around the bottom of the casing 33 within the compartment 35 are rollers or wheels 41.

Near the periphery of the disc B on its under side is an annular groove or the like 41, which receives the u per edge of the wall 34 to make a joint sufficiently tight to retain lubricant within the chamber 35 and yet to permit free rotation of the shaft 37 and disc B.

On the disc B on the under side thereof is-mounted a ring 42, having at its periphery an upwardlyiextdnding, annular flange 43, provided with; teeth 44.

The device justdescribed forms a worm wheel, which I have indicated generally by the reference character C.

A shaft 45 extends through the wall of the casing 33 and through the wall 34 and has on its inner end a worm 46, shown in Figure 5 in mesh with the teeth 44 of the worm wheel C. The shaft 45 is actuated from'a motor 47 having the shaft 48. by means of pulleys Resting upon lugs 52 on the frame members 3341 is the bottom member 53 of the pulverizer casing 33. The bottom member has an annular, upwardly extending peripheral side wall 54.

The diameter of the casing 33 at its upper part is a little less than its diameter at its lower part, as shown.

The shaft 37'extends upwardly through the bottom 53 of the casing 33, and a suitable. stuiiing box structure 55 affords a joint, which will prevent the escape of coal dust.

The grinding pan, A has inset into its upper surface an annular, sectional wear plate 56, the details of which are not here described. The grinding or pulverizing pan A has a series of radially projecting arms 57,

-' which support, an annular, sectional slotted ring 58 through whichthe ground fuel may drop downwardly upon the bottom 53. e

Certain of thearms 57 support downwardly, projectin scraper blades 59, the lower edges of whic are adjacent to the bottom 53 for scraping the ground fuel to the discharge opening in the bottom.

Mounted on the shaft 37 just above the bottom 53 is a radially projecting scraper arm 60, which has the same purpose.

The arms 57 also carry an upwardly extending peripheral rim or wall 61, which really forms partb of the pulverizing pan A.

Within the casing 33 are spaced muller wheels 62, having shafts 63, projecting through the side walls of the casing 33. The side walls are provided with suitable slots 64 to permit limited up and down swinging movement of the shaft63 and the muller Wheels. The outer ends of the shafts 63 are journaled in bearings 64a carried b the wheel carriers or yokes 65, which are suitably pivoted to the upstanding arms 66 on the frame member 33a.

The muller wheels 62 thus rotate freely and are permitted slight up and down movement.

The shafts63 carry fiber plates 67 adjacent to the slots 64 for covering the slots and preventing the escape of fuel therethrough.

Powder fuel handling mechanism A fuel pipe 68 extends from the bottom of the casing 33 near the center ofthe bottom member 53 laterally, as shown in Figure 2, for conducting the pulverized fuel away from the pulverizer casing.

The pipe 68 leads to a fan casin 69, in which is a fan or the like of any sui'ta le construction, not shown, operated from the motor 70. The fan casing 69 discharges'into a conducting pipe 71 leading to the top bf the pulverizing casin 33.

The powdered ml, which travels through I the pipe 68 is separated into the finedust,

which is conducted to the combustion chamber, and the larger particles, which are driven by the fan structure 69 and the air current through the pipe 71 back tothe pulverizer chamber.

The manner of accomplishing this separation will now be described.

A pipe 72 communicates with the top of thepipe 68 and leads .to a fan structure 73, in which is a fan of any suitable construction, not shown here in detail, operated from a motor 74.

A the combustion chamber.

From the fan structure 73, the fine dust is Automatic regulating structure The motor 25 may rest upon a suitably supported shelf or the like 78. A bell crank lever 79 is pivotally mounted, as for instance at 80, on the shelf 7 8. One arm of the bell crank lever 79 is connected as at 81 with the control rod 29 hereinbefore referred to, in such manner that the rocking of the bell crank lever will move'the rod 29 longitudinally, but

'will permit the free rotation of the rod. Thus by rocking the bell crank lever 79, the feed wheel maybe controlled for regulating the amount of coal delivered tothe pulverizer.

It is desirable that the various operations of the machine should be simultaneously automatically controlled for controlling the rocking of the bell crank lever according to the condition of the furnace and boiler.

I provide a diaphragm casing 82 'having therein a flexible diaphragm 83, subject on one side to steam pressure from the boiler through the pipe 84. On the other side of the casing 82 is a tubular extension 85.

The diaphragm 83 has ahead 86 to which is connected a rod 87 extended through the casing 82.

In the end of the extension 85 is an adjustable sleeve 88, having a threaded connection with the extension 85. A coil spring 89 is mounted on the rod 87 within the extension 85 and casing 82 and bears against the head 86 and the adjustable sleeve 88.

By adjusting the sleeve 88, the tension of longitudinally and rocking the bell crank. lever 79 for adjusting the sleeve drum 26 for regulating the size of the pockets 15, and consequently the amount of coal fed to the pulverizer. r p

When the steam pressure goes down, the

' operation of the parts is reversed by virtue of the action of the spring 89. v

- A rod 91 is pivoted to the other arm of the ,bell crank lever 79, as at 92 (Figure 2). At

the lower end of the rod 91 is a yoke 93, the

arms of which extend downwardly on opposite sides of the pipe 72.

The arms of the yoke 93 are connected by pins .94 extending through slots 95 in the pipe 72 with the sleeve 76, so that by raising or lowering the-rod 91, the sleeve 76 may be raised or lowered. v

It thus follows that when the bell crank lever 79 is actuated according to steam pressure, the sleeve 76 is slid up or down as the case may be. When the steam pressure goesup, the sleeve 76 is raised, and less fuel will be drawn fromthe pipe 68 and delivered to the combustion chamber. On the other hand, when the steam goes down, the sleeve 76 will be lowered into the passing stream of fuel and air, with the result that more fuel will be drawn to the combustion chamber.

In the pipe 72 is a butterfly control valve 96, the stem 97 of'which projects from the pipe and carries an arm 98. The arm 98 is connected by a link 99 with the rod 91, so that when the bell crank lever is actuated by in creasing steam pressure for decreasing the feeding of coal and raising the sleeve 76, the valve 96 will be moved accordingly'toward closing position; i

Provision is also made for simultaneously controlling the valve 19in the pipe 18 which conducts air to the feeder and therethrough to the pulverizer.

Referring to Figures 2 and 3, it will be seen that a bell crank lever 100 is pivotally mounted as at 101. One arm of-the bell crank lever 100 is pivoted to the rod 87. The other arm of thebell crank lever 100 is connected by a link 102 with the arm 21 on the stem 20 of the valve 19 in such manner that the movement of the rod 87, when it is actuated by thediaphragm on account of increasing the steam pressure, serves to rock the stem 20 for moving; the valve 19 toward-closing position. 7

Similarly when the steam goes down, and the spring 89 moves the rod 87, as shown in Figure 2, toward the right, such movement .of the rod 87 serves-to move the valve 19 to ward open position.

It isnot desirable, as has been said, to supply to the coal during its passage through my apparatus all of the air which is necessary for proper combustion. When enough air is supplied for that purpose, there is more danger of explosions due to the various causes, vsuch for lnstance as sparks that might be created in the machine.

' It is therefore desirable to have an auxiliary supply of air for the furnace, and it is,

of course,desirable that this auxiliary supply be controlled automatically in connection with the other controls herein mentioned. A flexible cable 103 is connected with the upper end of the rod 91 and extends over a suitably mounted pulley 104 andanother pul- 55, ley 105 to a furnace draft door 106. The arsteam pressure goes up for actuating the automatic controls, the draft door wlll be closed ormoved toward closing position, and

when the pressure goes down, the draft door 69 will be opened.

.I also provide means for controlling a damper door 107, by-which air is admitted to the stack 108. A flexible cable or the like 109 is connected with the door 107 and extends around the pulley 110, and is then conrangement of the parts is such that when the nected with the cable 103 in such .manner that when the door 106 is closed, the door 107 is opened, and vice versa when the door 106 is opened, the door 107 is closed. 0

I will now explain in greater detail the practical operation of my apparatus and the method which I practice in feeding pulverized coal to a furnace either with my present ora similar apparatus.

p The coal is supplied to the pipe- 11 in an wheel. Theefiective size of the pockets will depend upon the position of the sleeve drum 26. If that is at'the right-hand limit of its movement, as shown in Figure 3, the pockets will take and handle a large amount of fuel. If the sleeve drum is moved farther to the left, this will obviouslyreduce the size of the pockets and therefore reduce the capacity 95 of the feeder and'reduce the amount of coal discharged from the pockets 15 through the passage 32 into the pulverizer.

It will, of course, be understood that the position of the sleeve drum 26, which controls the supply of coal fed to the pulverizer will be regulated by the control mechanisms, 'hereinbefore described and hereinafter more particularly referred to, according to the oiler demand.

Air is admitted to the feeder casing 10 through the inlet passage 17 and the supply pipe 18. The air used is preferably preheatedin some suitable way, as for instance by taking it from the breeching or the hollow walls of the furnace.

It will be understood, of course, that the air used is fresh air.

The use of-the heated air this manner serves two desirable purposes. In the first place, it helps to take moisture out of the fuel, and in the second place, all of the waste'hea't units thus used effect so much of a saving.

The supply of air'through the pipe 18 is ;controlled by meansof the valve 19. This 12" valve 19 is actuated according to boiler demand in cooperation and simultaneously with the control of the feeder.

The coal passes from the feed wheel 13 through the passage 32 into the pulverizer or muller. It is, of course, obvious, that the air supplied tothe feeder casing passes into the pulverizer casing with the coal. The pulverizer casing is substantially airtight.

The coal drops upon the grinding pan A' above the pan bottom, so that very finely should be increased. The increasing or and by the rotation of the pan comes directly into the path of the muller wheels 62. Scraper blades 113 are suitably supported on the pulverizer casing and incooperation with the pan serve to move the coal inwardly, so that it will be in the paths of the muller wheels.

The pan is rotated from the motor 47, the shaft 48 of which transmits power to the pulley 49, the belt 51, the pulley 50 and the worm shaft 45. The worm 46 on the shaft 45 meshing with the teeth 44 rotates the supporting disc B and the pul verizer pan shaft 37 and the pulverizer pan A.

The coal is ground'by the muller wheels 62 and the wear plate 56. The muller wheels are permitted to rock up and down for a limited distance on account of the pivoted mountings of the carriers-65 on the arms 66.

The fine coal dust drops downwardly through the screens 58. The scraper blades 113 stand perhaps one-sixteenth of an inch ground fuel may pass under them.

The finely ground fuel drops onto the bottom 53 and is shoved around by the blades 59 and 60 and drops into the pipe 68, through which a current of air is constantly passing during the operation of the fan devices 69' and 73.

As the current of ground COZIlJ fiI1d air passes through the pipe 68, the very fine fuel is drawn upwardly through the sleeve 76 and the pipe 7 2 and passes through the fan structure 73 and thence through the pipe 75 to the combustion chamber. The coarser coal passes out of the discharge end of the pipe 68 and thence through the fan structure 69, by which it is blown through the pipe 71 back to the pulverizer. v

In order to insure the working of the machine with the maXimum of efficiency and to reduce the cost of labor and superintendence to a minimum, I have provided the automatic control mechanisms hereinbefore described.

It is obviously desirable that when there is an ample supply of steam in the boiler, the furnace fire should be reduced, and that when the steam supply goes down, the furnace {lire creasing of the fire is accomplished by controlling the amount of coal fed to the pulverizer,and the amount of pulverized coal supplied to the combustion chamber.

The feeding mechanism is controlled from the diaphragm 83 in the manner hereinbefore described.

The amount of coal supplied to the com the pipe 7 2 and theadjustment of the sleeve 76. The draft of air through the pipes just 4 .7

It will, of course, be understood that the mentioned is regulated by the valve 96 in the ner hereinbefore described from the diaphragm 83. The sleeve 76 issimilarly controlled from the diaphragm.

It has been found that it is highly desirable to control also the inlet of air to the pulverizer, and this is accomplished by the mechanism hereinbeforc explained for controlling the valve 19.

It is obvious that it would be difficult to accurately control the supply of fine coal to the furnace, if all thecoal groundshould be conducted to the furnace. It would, of course, not be desirable to have the coal supply choke up, and I have therefore provided the means herein described, comprising the fan structure 69 and the return pipe 71 for conducting back to the pulverizer, the coal not used for the furnace.

The step of my process, which involves carrying back to the pulverizer, some of the coal, is' also important because it is desirable to use for combustion only the coal which has been ground the finest.

It will, of course, be understood that the coal, which has been ground the finest is subject to the mostcomplete combustion. Some coarser particles of coal will be discharged from the pulverizer, and these coarser particles are carriedback for another grinding.

I have already explained that it is desirable to supply auxiliary airto the combustion chamber. It is of course obvious that it'is desirable to control this auxiliary air supply in accordance with boiler demand, and this is accomplished by means of the automatic control for the door 106, which has already been described.

It is well-known that in any furnace, it is desirableto control the stack door, and I have provided for the automatic control of that door 107 as hereinbefore explained.

A general advantage arises from the flexibility which is possible in the use of my apparatus and process.

,I will now call attention to some of the 6 features of my "apparatus and machine by tion takes place.

Attention is called to the arrangement of the parts wherein a pulverizer or muller of thiskind is contained within a substantially airtight casing which I believe to be a novel feature of structure, and which makes possible the use of air in the manner herein explained.

particular form of, mechanism,which I have shown here, is intended to be illustrative,

and that I do not desire to limit myself to the specific form of mechanism disclosed.

I claim:

5 1. In an apparatus of the'class described,

a pulverizer, fuel feeding mechanism for supplying fuel thereto, means for supplying air to the feeding mechanism to be mixed with the fuel before the fuel enters the pulverizer,

3 means-for Withdrawing fuel from the pulverizer, and means for simultaneously controlling the feeding mechanism, the supply of air to the feeding mechanism and the & drawing of fuel from the, pulverizer.

2. In an apparatus of the class described,

a pulverizer, fuel feeding mechanism for 3. In an apparatus of the class described,

a pulverizer, means for feeding fuel thereto, means for withdrawing fuel from the pulverizer and separating the finer from the coarser fuel, and means for simultaneously, cooperatively controlling the feeding means andthe fuelwithdrawal .and separating means whereby ademand for more uel cause coarser fuel to be drawn with the fine fuel in the separating means. 4. In an apparatus of the class described, a pulveriz'er, fuel feeding mechanism for supplying fuel thereto, means for supplying'air to the feeding mechanism, means for drawing fuel from the pulverizer'and returning it to the pulverizer, means for sepa'ratingthe finer portions from the fuel being returned to thepulverizer, and means for cooperatively controlling the feeding mechanism, the supply of airto the feeding mechanism, and thedrawing of the finer portions of the fuel from the Ifuel drawing and returning means.-

a v 1 5. In an apparatus of the class described, to a steam plant having a combustion chamber, means for separating crushed fuel into finer and coarser parts and conducting the finer fuel to thecom bustion chamber, comprising a conducting pipe, a means for creating air currents therethrough, a second pipe leading from the upper part'of the first pipe for taking-off the finer fuel and conducting it to the combustion chamber, a means for creating a draft of air through the second pipe away from the first pipe, a sleeve'in the second p1 e, means for adjusting the sleeve v for inserting it to different distances of projection into the first pipe, a valve in the second. pipe, and means for cooperatively, controllingthe sleeve and valve.

conducting the finer parts to the combustion 6. In an apparatus of the elm described, a steam plant having a combustion chamber and a boiler, a fuel crusher, means for separating crushed fuel into finer and coarser parts and returning the coarser parts to the m crusher, means for conducting the finer parts to the combustion chamber, comprising a conducting pipe, means for creating a draft of air therethrough, a second pipe leading from the upper part of the first pipe for taking-off the finer fuel and conducting it to the combustion chamber, means for creating a draft of air through the second pipe away from the first pipe, a sleeve in the second pipe, means for adjusting the sleeve for projecting it different distances into the first pipe, a valve in the second pipe, a draft door for controlling auxiliary air su ply to the combustion chamber, and means or cooperaitdively controlling the valveand the draft oor; 7

7 .In an apparatus of the class described, a steam plant having a combustion chamber and a boiler, means for separating crushed fuel into finer and coarser parts and con-. ducting the finer parts to the combustion chamber, comprising a conducting pi a means for creating a draft of air t ere- ,through, a second pipe leading from the upper part of the first pipe fortalcing off the finer fuel and conducting it to the combustion chamber, means for creating a draft of airthrough the second pipe" away from the first pipe, a sleeve in the second pi e, means foradjusting the sleeve. for projecting it different distances into the first pipe, a valve in the second pipe, a draft door iforcontrolling auxiliary airsupply to the combustion cham .ber, and means for cooperatively controlling the valve,-the draft door and the sleeve. 8. In an apparatus of the class described, a steam planthaving a combustion chamher and a boiler, means for separat' crushed fuel into finer and coarser parts did chamber, comprising a conducting pipe, means for creating a draft of air therethrough, a second pipe leading from the upper part of the first pipefor taking ofi the finer fuel. and conducting it to the combustion chamber, means for creating a draft of air through-the second pipe, a sleeve in the second pipe, means for adjusting the sleeve for pro ecting it differentdistances into the first pipe, a draft door for controlling aux- .iliary a1r supply to the combustion chamber, a fuel pulverizer, a means for feeding fuel thereto, and means for coo ratively controlling the sleeve, the draft oor and the feeda ing means. r r

9. In an ap aratus of the class described, a steam plant having a combustion chamber and a boiler, means for separating crushed fuel into finer and coarser arts and conducting the finer parts to e combustion chamber, comprising a conducting pipe,

air through the. second pipe, a sleeve in the second pipe, means for adjusting the sleeve for projecting it different distances into the first pipe, a draft door for controlling auxiliary 'air supply to the combustion chamber, and means for cooperatively controllingihe sleeve and the draft door according to the steam condition in theboiler.

10. In an apparatus of the class described, a steam plant having a combustion chamber and a boiler,'means'for separating crushed fuel into finer and coarser parts and conducting the finer parts to the combustion cham' ber, said means comprising a horizontal conducting pipe, means for creatinga draft of air therethrough, a vertical pipe leading from the upper part of the first pipe for taking off the finer'fuel and conducting it to the combustion chamber, means for creating a draft of air through the second pipe, means for supplying auxiliary air to the combustion chamber, a sleeve in said vertical pipe, means for adjusting the. sleeve for projecting it different distances into the first pipe, a device for controlling said supply of auxiliary air to the combustion chamber, a fuel pulverizer having discharge connection with said conducting pipe, a means for feeding fuel thereto, and means for cooperatively controlling thesleeve, the device, and the feeding means according to the steam condition in the boiler.

11. In an apparatus of the class described, a steam plant having a combustion chamber and a boiler, means for separating crushed fuel into finer and coarser parts and conducts second pipe leadin from the upper part of the first pipe for taiing off the finer fuel and conducting it to the combustion chamber, means for creating a draft of air through the second pipe awayfrom the first pipe, a sleeve in the second pipe, means 'for adjusting the sleeve for projecting it different distances into the first pipe, a draft door for controllin'g auxiliary air supply to the combustion chamber, a fuel pulverizer, a means for feeding fuel thereto, and means for cooperative-c ly controlling the feeding means, the valve,

sleeve and the draft door according to the condition of steam in the boiler.

12. In an apparatus of the class described, a'steam plant havifiga' combustion chamber and a boiler, means forseparating crushed fuel'into finer and coarser parts and conducting the finer parts 'to the combustion chamber, comprising a. conducting pipe,

means for creating a draft of air therethrough, a second pipe leading from the upperpart of the first pipe for taking off the finer fuel and conducting it to the combustion chamber, means for creating a draft of air through the second pipe, a sleeve in said second pipe, means for adjusting said sleeve for projectin it dilferent distances into the first pipe, a evice for controlling auxiliary. air supply to the combustion chamber, a fuel pulverizer having discharge connection with said conducting pipe, a means for feeding fuel thereto, means for cooperatively controlling the feeding means, the sleeve and the auxiliary air control device, means for supplying air to the feeder, and means for simultaneously controlling such air supply in cooperation with said first controlling means.

13. In an apparatus of the class described, a steam plant having a combustion chamber and a boiler,.means for separating crushed fuel into finer and coarser parts and conducting the finer parts to the combustion chamber, comprising a conducting pipe, means for creating a draft of air therethrough, a second pipe leading from the upper part of the first pipe for taking off the finer fuel and conducting it to the combustion chamber,

means for creating a draft of air through the second pipe away from the first pipe, a sleeve in the second pipe, means for adjusting the sleeve for projecting it different distances taneously controlling such'air supply in cooperation with said first controlling means.

a steam plant having a combustion chamber and boiler, a pulverizer, fuel feeding mechanism for supplying fuel thereto, means for supplying air to the pulverizer, means for drawing'fuel from the pulverizer and supplying it to the combustion chamber, and means for simultaneously controlling the feeding mechanism,.the supply of air to the pulverizer, and the drawing of fuel from the pulverizer, according to the pressure of- 14. In an apparatus of the class described, 1

controlling the feeding mechanism, air supplying means and separating means.

16. A method of handlin coal comprising the supplying of air to t e coal before it is pulverized and during the pulverizing operation, the removal of the'coal from the point of pulverizing and the simultaneous cooperative controlling of the supply of coal for pulverizing, the supply of air to the coal, and the removal of the coal from the point of pulverizing. C

17. In a process of pulverizing coal, feeding the raw coal to a pulverizing zone and pulverizing the same, supplying air to the coal before it is pulverized and during the pulverization thereof, removing the fuel from the pulverizing zone, and simultaneously and :cooperatively controlling the supply of air and fuel withdrawal.

18. The process of feeding coal for pulverizing, pulverizing the coal, supplying air to the coal before and while it is being pulverized, withdrawing the coal from the point of pulverizing, and separating it into finer and coarser portions, and simultaneously, cooperatively controlling the supply of coal for pulverizing, the air supply to the coal and the withdrawal and separation of the coal.

19. The process of preparing and feeding fuel to a steam plant having a combustion chamber and a boiler, comprising feeding the fuel to a pulverization zone, pulverizing the fuel, supplying air to the fuel before and while it is being pulverized, withdrawing the fuel from the point of pulverization, conveying it-to the combustion chamber, and simultaneously, cooperatively controlling the air su'p'ply,the operation of the fuel withdrawal and movement of the fuel to the combustibn chamber accord-ingtg the pressure of steam in the boiler.

ized fuelto 20. The process of preparing and feeding fuel to a steam plant having a combustion chamber and a boiler, comprising pulverizing the fuel, supplying air to the fuel before and while it is being pulverized, conveying the fuel to the combustion chamber, and simultaneously, cooperatively controlling the air supply and the operation of the fuel conveyance to the combustion chamber and the supply of fuel for pulverizing. Y

21. The process of preparing and feeding fuel. to a steam plant having a combustion chamber and a boiler, comprislng pulverizing the fuel, supplying air to the fuel before and duringlthe pulverizing, conveying the pulverel to the combustion chamber, and simultaneously, cooperatively controllin air supply and the movement of the puTverized fuel to' the combustion chamber, and also simultaneously, cooperatively regulating, controlling and suppl' ing .an additional amount of air to the coin ustion chamber.

22. The process of preparing and feeding a steam vplant having a combustion the chamber and a boiler, comprisin feeding the fuel to a pulverization zone, pu verizing the fuel, supplying air to the fuel as it is fed and whlle in the pulverization zone, withdrawing the fuel fromthe pulverization zone and separating the finer from the coarser pulverized fuel and conveying it to the combustion chamber, the coarser fuel being returned to the zone of pulverization and further treated therein for pulverization, and simultaneously, cooperatively controlling the air-supply, the supply of fuel to the combustion chamber, the supply of fuel to the pulverization zone, and the separation operation, 23. The process of preparing and feeding fuel to a steam plant. having a combustion chamber and a boiler, comprising pulverizin the fuel, supplying air to the fuel before an during the pu verizing, conveying the pulverized fuel from the point of pulverizing to the combustion chamber, and simultaneously, cooperatively controlling the air sup ply and the movement of'the pulverized fuel to the combustion chamber, and simultaneously, cooperatively controlling, regulating and supplying an additional amount'of air to the combustion chamber, the coarser particles of fuel being separated from the finer particles and returned for further pulverizing asthe fuel is conveyed along toward the combustion chamber.

In an apparatus of the-class described,

'a steam plant having a combustion chamber and a boiler, means for separating crushed fuel into finer and coarser parts conducting the finer parts to the combustionchamber,

comprising a conducting pipe, means for creating a draft of air therethrough, a second pipe leading from the upper part of the first pipe for taking off the finer fuel and conducting it to the combustion chamber, means for creating a draft of air through the second pipe, a sleeve slidably mounted in said second pipe, means for adjusting said sleeve for projecting it difierent distances into the first pipe, a device for controlling auxiliary air supply to the combustion chamber, and means for cooperatively actuating the sleeve ad usting means and the device, a fuel pulverizer having discharge connections with'said con.- ductin pipe, ameans for feeding fuel thereto, an means forcooperatively controlhng the feeding means, and the sleeve, means for supplying air to the feeder, and means forsimultaneously controlling such air supply in cooperation with said first controllmg' means. 1

Des Moines, Iowa, April 16, 1926. V

GEORGE A. CONRATH.

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