US1775608A - Powdered-coal furnace - Google Patents

Description

H. VAN DEVENTER POWDERED COAL FURNACE Sept. 9, 1930.

Filed Feb. 1, 1927 2 Sheets-Sheet 1 v mm Q 4% kw .J ,wwv a N% J N? wt \N k QM MW Nww QM x Q \Q o A. .%N *N QN N.

NN L w L Patented Sept. 9 1930 HORACE VAN DEVENTER, on KNOXVILLE, T ENNESS EE POWDEBED-COAL FURNACE Application filed February This invention relates to improvements in burners for "the employment of powdered fuel suchas coaland more particularly concerns a feeding arrangement and burner system for such employment. o

It has heretofore been proposed 'to employ powdered coal on a large scale for-heating furnaces, and myinvention relates to heatmg devlces employing such fuel, and lncludes' therewith certain features whereby it is possible to employ powdered coal burners even upon the smaller installations. The pow dered coal burner-of the present invention may be employed ,for various heating and power purposes, in furnaces, fire" boxes,

stoves, cutting torchesfforges, etc., for stationary or portable'work in 'steamboiler's,

locomotive engines,'tr actors, etc.

In particular, the invention proposes the p employment of means to prepare a suspen-- sionof finely powdered coal in a current of air whereby a quasi-gaseousstate is attained 1n which the mixture-1s readily and 'easlly ignited and-burns like an entirely gaseous mixture. A further @feature of this invention is the provision of abaffle orflame spreader forcontrolling the action ofthe burner, preventing theburning ofthe boiler plating, and preventing the loss of heatbyuseless radiation. 7 Furthermore, a feature of this invention is 3 the provision of simple means forgenerating steamfor introduction into the flame et whereby to temper or reduce the intense heat produced bythe com- 'bustion of the quasi-gas.

VVith'these and other objectsin view as will appear in the course of the following specification and claims, I have represented my invention in one illustrative form on the accompanying drawings, as applied to a fur nace construction of the stationary type.

Figure lis a side elevation of the plant, showing parts of the mixture producing ,;system and of the burner and furnace in section. i Fig. 2 is an end elevation blower system.

of the hopper'and Fig. 3 is a section through the mixing chamberonanenIarged scale. I 1 Y 1, 1927. Serial No. 165,165.

Fi 4 is a section .through the mixing cham lier on line 4-4 ofFig. 3.

" on line 5'-5'of Fig. l. V

Fig. 6'is an end view of the baffle device, with the pipe system in section on line 66 of Fig. 1 on an enlarged scale.

Fig. 7 is'a plan view of tl e valve employed to regulate the delivery of powdered coal.

In these drawings, the burner-is to. be employed 'in a'fu'rna'ce whichhas the front wall 10 and'the arch 11 of well known type. a

The fuel preparing structure comprises the hopper 12 for the; reception of finely powdered coal, this hopper having a trough-like bottom to receive 'the endless screw 13 which is carried by a shaft14 ournaled at its ends in the hopper walls and projecting therefrom at the side away from the furnace to receive the bevel gear 15'whichisin mesh with a similar bevel gear 16 mounted on a shaft 17, which in turnis supported by the journal brackets 18'. This shaftl7zcarriesat its lower of the same. a v

- This outlet aperture is closable by a valve plate 24 which has a V-shaped' opening 9.5 therein to more or less close the aperture 2?) according to the desire of the furnace opera-- t0r. The coal dust within the hopper 12 is continuously agit'atedfiby the screw 13 and passes in a regulated stream through the.

' aperture 23 as determined bythe valve plate 24:. This valve plate slides in a pocket provided at the bottom of the hopper for the designated purpose. i

Likewise mounted for drive by the shaft 21' of the motor 22 are the low pressure and high pressure fans for delivering air for the combustion of the coal powder. The low pressure fan 26-. is connected by an eduction pipe 27- to an antecharnber28 of the fuel mixing block. The highpressure fan 29 is con.

the container toward the outlet aperture 28 nected by an eduction pipe 30 to a Y-connection 31 on the outlet line 36 for the fuel mixture for the fuel mixing block as will be more fully set forth hereinafter. The fuel mixing block 32 is preferably formed integral with the bottom of the hopper 12, and at all events has the clear passage 23 in communication therewith, as governed by the valve plate 24. The antechamber 28 for the reception of the low pressure air from the eduction pipe 27 is partially shut off from the general mixing chamber by a substantially horizontal inwardly directed flange 33, and a downwardly projecting lip 34 which serves to form a trickle plate or funnel for the coal dust entering through the aperture 23-. A horizontally and inwardly projecting flange 35 at the opposite side of the mixing block serves as a baffle to cause the mixture of air and coal dust to pass in a tortuous path through the block, from the point of initial contact at the lower edge of the lip 34 to the outlet pipe 36. A plug 37 is preferably provided in the wall of the mixing block 32 in line with the outlet pipe 36 of the bottom of the mixing block chamber, whereby it is possible to remove accumulations of material if desired.

The outlet pipe 36 passes to the Y-connection 31 and thence by the fuel pipe 37 to the: interior of the furnace, where it is opened at, its end. The portion of the fuel pipe 37 within the furnace and the furnace wall. is surrounded by a jacket 38 providing an annular chamber 39. Theupper part of this jacket 38 likewise serves to support a battle: device which extends forwardly and downwardly over the outlet of the burner and ishollow to:

form the water circulating chambers 41, 42 with the wall 43 therebetween. These chain-- bers are closed except for communication with each other and the pipes 47, 48, and at the extreme end farthest into the furnace, a downwardly projecting ledge 44 is provided to receive the corresponding end of a refractory lining 45, which. at its rear end is supported by a toe 46 engaged between the jacket 38 and the body 40 of the bafiie device.

A water inlet pipe 47 is connected at the end of the chamber 41 to deliver cooling water into the body of the battle device 40, where it passes through the chamber 41 around the. baffle plate 43 into the chamber 42 and makes its exit from this baffle into an outlet pipe 48 in a highly heated condition, and passes to a T 49 and thence by the discharge pipe 50 to a radiator 51 or other similar employing device, whence it may be again brought back into the pipe 47 and to the baffle device for further cooling effects therein.

As the water from the baffle device is used up in the jacket 38, its place is taken by further water which is admitted from the fresh water pipe 60 through the control valve 61 into the inlet pipe 47.

A small pipe 52 connected to the T 49 through a regulating valve 53 leads to the chamber 39 within the burner jacket 38, and serves for delivering steam or hot water into this chamber, wherein it is heated by the heat of the jacket as produced by the radiation from the flame so that it may be discharged as steam through the apertures 54 at the end of this chamber 39 within the furnace, and serve to moderate and control the heat of the flame, according to the manipulation of the valve 53 which determines the quantity of steam thus admitted.

It is apparent that the hot water from the baflie device 40 may be employed for other purposes than that of the radiator 51: and that this battle device constitutes in effect a water back for heating water: and may be employed as such when the back is utilized with a house heating plant.

The method of operation of this system: is as follows: A supply of powdered coal is. placed in the hopper 12, and the electric motor 22 is set into operation. The motor drives the fans. 26 and 29 whereby currents of air are caused to pass through: the respec tive pipes 27 and 30, and to enter the. chamber of the furnace. As the motor turns, the endless screw 13 is caused to revolve to prevent any packing or stacking of the powdered coal in the hopper'12. The. furnace operator then opens the. slide valve plate. 24 to a greater or lesser extent to causethe pow dered coal to enter the mixing chamber in the block 32, Where it is caught and mingled intimately with the air under. low pressure which is entering through the antechamber 28. This mixture of air and pulverized coal suspended in a cloudy condition therein, and being a quasi-gas, passes into the outlet pipe 36 and to the Y-union 31. At the same time: the current of air under high pressure in. the pipe: 30 flows. through this union and by its ejector action facilitates the movement of the fuel mixture in the pipe 36 and becomes mixed therewith in the union31 and the out let pipe 37 therefrom, and finally issues from the free end of this pipe as a blast of'uniformly mixed air and fuel". This blast is ignited in the usual manner, and as its temperature increases, the flame heats the surrounding elements. The blast of flame is'proje'cted across the refractory lining 45,. where by it is prevented from direct contactwith any of the metal parts of the burner structure. The burner tip is maintained at a relatively low temperature by the chamber 39 surrounding it which is filled with water or steam as the case may be. The heat transmitted through the lining 45 and obtained; by the exposure of the baflie 40 to the heat radiated within the furnace effects a heating of the Water within this baffle, and on the other hand, the water within the bafiie maintains it and the lining at a relatively low. temperature.

The Water for the baflle enters through the feed pipe 47 and makes its exit through the delivery pipe 48, and may .pass through a heat consuming device such as the radiator 51, and then be returned to the feed pipe 47 in any-suitable manner. It is obvious that this water may also be employed as feed water for a boiler structure. The branch pipe 52 and its valve 53 permit the delivery of a quantity of this heated water or steam from the baflie device 40 into the chamber 39, where it serves on the one hand to cool the end of the burner pipe 37, and on the other hand is increased in temperature and converted to steam so that it is projected through the open ings 54 at the furnace end of the chamber 39 and mingles with and regulates the temperature of the flame blast itself.

The proportion of powdered coal to air is regulated by the adjustment of the slide plate 24, and by the speed of the motor 22.

In this way and manner, the powdered fuel is maintained in its finely divided form and cold while in the hopper, and by means of the agitator in this hopper all packing or jamming of the massof fuel is prevented, so that a regulated and uniform stream passes through the valve structure, and trickles down over the apronand presents itself in a uniform and thin sheet to the blast of incoming air. Furthermore, the low pressure air is given momentarily a greater speed by the restriction caused by'this downwardly extending apron, while the tortuous passage through the mixing block itself is of larger section, so that the mixture occurs by the successive reversal of direction and inversion of the air current within, the mixing block. As this inixturepasses to the Y-connection, it is moved at a relatively low speed and with a relatively insuflicient quantity of air. The air under high pressure andat high speed is then introduced into this semi-completed mixture, whereby the speed is accelerated beyond the velocity of development of the quasi-gas, so that it may be burnt at its passage from an orifice. even though this orifice be oflarge size, without danger of flaming back. Likewise thisair at high speed and pressure is incorporated and mixed thoroughly with the semi-completed mixture to form a mixture of predetermined composition characteristics, so that a complete combustion of the powdered fuel shall occur in the flame as it leaves the nozzle orifice. The mixture is therefore accomplished primarily by air at low pressure and speed, and completed by air at high pressure and speed.

It is obvious that the invention is not limited to the specific form of apparatus shown, but that it may be modified within the scope of the appended claims.

What I claim as new is:

1. In a burner for powdered fuel, a nozzle adapted to deliver a flaming current of mixed fuel and air at high speed, a bafiie device arranged in the path of the flaming current and comprising a water conduit. means for admitting water to said conduit and discharging it therefrom, a jacket enclosing said nozzle adjacent its orifice and having apertures arranged annularly about the discharge orifice of said nozzle, and a valved conduit from said discharging means to said jacket whereby water from said conduit after being heated insaid bafiie device may be brought into said jacket and discharged as steam as an envelope for said flaming current.

2. In a burner structure, a nozzle adapted to deliver a flaming current of mixed fuel and air at high speed, a jacket surrounding said nozzle adjacent its orifice, a baflie device located opposite said nozzle in the path of the flaming current and having enclosing walls to form a heating chamber, a central partition extending from one end of said chamber and terminating short of the other end thereof, means to admit water to said heating chamber, a ledge on the end of said device away from the nozzle, a refractory lining on said baffle device in the path of the flaming current and supported by said ledge,

a conduit connecting the interior of said jacket with said heating chamber, apertures being formed in said jacket around the orifice'of said nozzle so that the fluid from the baffle may pass into said jacket to cool the same, and be delivered in the form of steam from said fluid in an envelope surrounding the flaming current.

"3. A burner structure as in claim 2, in which said jacket, baffle device and ledge are formed integrally.

4. In a burner structure, a nozzle adapted .to deliver a flaming current of mixed fuel and air at high speed, a cooling jacket surrounding said nozzle adjacent its orifice, a hollow baffle device located in the path of the flaming current from said nozzle and providing a heating chamber, means to admit water to said heating chamber and to conduct heated fluid from said heating chamber into said jacket to be further heatedtherein, thereby serving to cool said acket, said jacket having orifices arranged peripherally around the nozzle whereby the vapor under pressure from said jacket is caused to produce an envelope surrounding the flaming current.

In testimony whereof, I aflix my signature.

' HORACE VAN DEVENTER.

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