US1878926A - Pulverized fuel burner - Google Patents

Description

Sept. 20, 1932. YARROW 1,878,926

PULVERI ZED FUEL BURNER Filed June 15, 1929 Patented Sept. 2%, 1932" curiae sires HAROLD EDGAR YARROW, or GLASGOW, soo'rnnivn PULVERIZED FUEL BURNER,"

Application filed June 13, 1929, Serial No. 370,5 69,and in Great Britain August 24, 1998.

One object of the present invention is to obtain as short a flame as possible consistent with eflicient combustion in a pulverized fuel burner, so that the size of the combus- 5 tion chamber can be kept within comparatively small limits. e

To ensure this result it is necessary to have a zone of high temperature where the powdered fuel first enters the furnace, so that the is hydrocarbons in the fuel will be immediately set free and at the same time the temperature of the residual particles of carbon will be raised to such an extent that these particles will immediately combine with the oxygen supplied for their combustion.

According to the present invention this high temperature zone with its consequential advantages is obtained by so constructing the burner that some of the ignited fuel will '20 be drawn back towards and into the burner,

thereby heating one or more of the entering fuel mixture constitutents by direct contact.

This is effected by introducing a Venturi constriction and nozzle in an annular passage through which one or more of the fuel mixture constituents pass to the combustion space, thereby reducing thepressure locally and inducing a backward flow of ignited fuel towards and through the Venturi nozzle into the entering fuel constituent.

This and other features constituting the present invention are more specifically described with reference to the accompanying drawing, wherein Fig. 1 is a central longi- 1 tudinal section of a burner embodying the invention, and Fig. 2 is an end elevation thereof. 7

In the burner shown the pulverized fuel and primary air supply enter the outer tube H through the passage C, while the secondary air supply is derived from an air box or trunk 13 formed between the transverse ,plates R. Air from the airbox or trunk B is supplied to the tube H through a passage between vanes D mounted in said passage at an I rality of nozzles, is preferably. directed someinclination to the radii of the tube H;(by which it is given a g'yratory motion) and thence to the annular inlet'S leading to the combustion chamber. r .7

The annular passage M between the outer tube H and the inner tube Eof the burner is formed witha Venturi constriction at an'intermediate point, and at this point the inner burner tube E is'divided transversely and has its'adj acent ends shaped to form an an-' nular constricted nozzle -N (or alternatively has nozzles formed in its wall) leading into the Venturi constrictionin the'passage M. This annular nozzle-N, or an equivalent plu- '60 what towards the furnace end of the passage M. y I

The delivery or furnace end of the inner tube E is preferably fitted with a sliding 8X:- tension piece Gr, which can be projected into the furnace to a greater or less extent, as by means of a rod Q, which is suitably supported in the wall of the passage 0 and in the plate 0 which closes the outer end of the tubeE. This platemay be a fiat plate as shown in full lines in'Fig. 1-, or it may be of other suitable shape.

The reduction in pressure within the burner, due tothe'Venturi constriction, in duces a backward liow'from the combustion space of hot gases which pass through the nozzle N and mingledirectly with the fuel constituent or constituents whichenter the burner through .the passage C, so that the latterare heated to a comparatively high temperature before their delivery to the furnace through the annular discharge aperture S. The acent edges of the two parts of the tube Ejare preferably made bulbous and shaped so as to form between them a convergsing nozzle N, as stated abo'ye.

The result of his construction isthat'the fuel mixture constituent or constituents I whichenterthrough the nozzle. C are delivcred to the combustion space of .thefurnace at a high temperature and consequently there i i will be a zone of high temperature within the combustion of the fuel.

the'passage M. p g Having thus described the nature of the i form a conicalvortex of rapidly increasing area, with the result that there-is a reduction 4. A pulverized fuel burner according to claim 2, comprising an air trunk surrounding the fuel conveying duct, passages leading from said air trunk to the said duct near the discharge end thereof, and vanes in said passages inclined to the radii of said duct adapted toiimpart a whirling motion to the air passing therethrough. In testimony whereof I have signed my name to this specification.

HAROLD'EDGAR YARROW.

of pressure at the edge T of "thes-leeve U which projects into the combustion space and encircles the discharge end of the burnerfl Consequently not only is the inner partpf the expanding Vortex of burning fuel turned back 7 on itselfinto the mouthof. the tube G, but the outer part of the expanding vortex is turned back on itself around the rear edge of the sleeve Ufso that thefuelis exposed to direct Contact with the flame as it enters the furnace. Complete gasification of the hydrocarbons is thereby obtained, and the carbon particles are also raised to a temperature at which theyimmediately ignite, thereby making the resulting flame short and intense;

g It may be desirable to give agyratory mo- 1 tion to the fuel constituent or constituents which enter the burner through the inlet pipe G prior to their discharge from the end of the passage M, and this may be doneby a convenient arrangement of inclined or helical vanes situated at'or nearthe discharge end of i said invention and the best means [know of carrying the same into practical effect, I claim 1. A pulverized fuel burner-comprising a duct to convey a fuel constituent to a furnace,

a second duct disposed within .the firstduct closed at one'end and leading at the. other end to the fun'a-ce, a Venturi constriction formedby the inner and outersurfaces respectively of the first and second ducts, the second duct having in its wall an aperture substantially in the transverse planeof the I said Venturi constriction.

2. A'pulverlzed fuel burner comprising a duct to convey pulverized fujel and air to a furnace, a second duct situated within the firstduct and closed at one end and leadingv at the other end into the furnace, a Venturi constrictionformed between the. inner and outer surfaces respectively of the said first and second ducts, said second duct having in its wall an aperture substantially in the trans-,

verse plane cfthesaid Venturi constrictiom 1 3, A pulverizedfuel burner according to claim 2, comprising an air trunk surroundincg the fuel conveying conduct and passages lea ing from said air trunk to the said duct near the dlscharge end thereof; I

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