US1926637A - Furnace for burning pulverized fuel - Google Patents

Description

Sept. 12, 1933. s SUFFERN 1,926,637

FURNACE FOR BURNIbiG PULVERIZED FUEL Filed Aug. 30, 1927 Patented Sept. 12, 1933 .ii-vArsnr"orricr FURNACE FOR BURNING PULVERIUZVED FUEL Ernest S sbury Suffern, Montclair, N. .L, as:

signer to Humphrey Douglas don, England Tollemache, Lon- L V I I Application August so, 1927, Sean No. 216,407,

and in GreatBritain, Septemberl, 1 926 v1 Claim, 101. 110528) This invention relates to apparatus for burning I extinguished, causing the mixture of gaseous and non-gasifiedfuelto pass, while still burning, out of the primary combustion chamber together with, or at the same time as, a quantityof secondary airsufiicient to support complete combustion,,int'o a-secondary combustion chamber in which secondary combustion chamber the burning of the fuel is continued. a

Qne of the objects of the present invention is to provide improvedapparatus for burning powdered fuel by the aforesaid method, such apparatus enabling a very long path of travel of fication chamber. v V I In the improved apparatus according to the .3 present invention the fuel is projected-into the from the outlet of such chamber and obliquely to the axis of the chamber so that it passes on to the opposite side wall of the gasiflcation chamber from whence it is deflected onto the front end wall and so caused to return and flow to wards the outlet through and around the incoming stream of fuel.

In thus striking the wall of the gasification chamber the stream of fuel is somewhat retarded in its flowbut such retardation is also supplem'ented by other means such as restricting the size of the outlet and by the provision of suitable;

battles. The size of the outlet must however not extinction of the flame, as it is intended that the partially gasified fuel shall pass into the secondary combustion chamber whilst it is, still burning, the combustion within-the secondary combustion chamber being then a continuance tion or primary combustion chamber. a

It will thus be seen that by admitting the fuel-in such fuel is caused to traverse a path which is the fuel to be employed without increasing correspondingly the size of-the generator or gasiinterior of the gasification chamber through aninlet in one side wall thereof in a direction away.

be restricted to such an extent as will 'cause theof the combustion initiated within the gasifica,

the manner according to the present invention in the form of a loop. There is thus avoided the baffling effect produced when thefuelis admitted coaxially and directedt'owards'the opposite end wall which baffling effect results in the produc: tion of a somewhat" quiescent region, in which the non-gasified particles of the fuel have a tendency to deposit. i 1 r In order that thev invention maybe clearly understood and carried into effect one construction of apparatus injaccordance therewith will now be described by way'ef example by aid of the accompanying drawing in ,which:- Figure, l, is a longitudinal vertical section through a combined primary andsecondary com? bustion chamber showing the apparatus according to the invention applied to'a steam gen erator of the Lancashire. or Cornish type, and

FigureZ shows, in the'lefthand half, a trans-' verse section and, in the righthand' half, a front elevationof the-out1et for effecting an intimate mixing of pro-heated secondary air with the products of partial combustion.

' Referring to Figure '1' the primary combustion chamber A comprisesan outer shell 1 of metal and aninner liner 2Qof refractory bricks or other refractory materialwhich' liner is spaced from the shell 1 to provide a space 3 forthe circulation and consequentpreheating of the sec ondary air which enters such space through the openings 4. ,The bottom 5 of this"chamber is sloped downwardsfrom theneck or outlet '6 to the front end wall12i andat such lower end an. opening 7, normally closed by a door 8, is providedf Pulverized fuel together'with primary'air are conveyedtothe inlet C by way of a feed pipe 9 either directly froma suitable pulverizer or from a storage and, in'conseque'nce of the shape andinclinationprsuch inlet, this fuel is pro 'jeoted towards theinclined bottom 5'obliquely to the axis of the chamber. "From this inclined surface it is deflected onto the end wall2 from I whichlit is againdeflected and caused to travel through the chamberythrough and around the incoming fuel and finallyout through the outlet 6 into the secondary combustion chamber B.

The fuel is thus caused to travel approximately thep athindicated by the arrows and byso doing is caused to remain withinlthe primary chamber a length oftime sufficient for the desired partial gasifieation totake'place. Byreturning past the incoming fuel the partiallygasified fuel'is caused ,to ignite the incoming fuel practically at the moment of its first entry. This feature although not novel per se is'thus decidedly advantageous as it results in reaction taking place throughout its.

' her is also a factor of great importance and as the maintenance of this heatis dependent upon such period being adequate, provision is made to ensure that the velocity of the burning fuel in its path through the primary combustion chamber shall be suiiiciently retarded. This re tarding effect is produced on one hand by thepar ticular path the stream of fuel is causedto take and on the other hand by making the outlet' 6 of an area smaller than the area of. the front end of the combustion chamber.

In the example, of apparatus illustrated, which is expressly designed for use in connection with large fire-tube boilers of the LancashireWand Cornish types, the primary combustion cham her is mounted upon wheels or rollers 10 whereby;

the. same may be wheeled up to the front end .of the boiler 11 and its outlet detachably coupled to the existing flanged end of the fire-tube 12 in the manner'indicated generally at 13.

By this means. the products of partial combusti'on are caused to pass directly into the secondary combustion, chamber B without th'e flame being. extinguished, The pre-hea-ted secondary 7 air is caused to mix with theseproducts of par tial combustion within theopening 14 constituting the inlet to the secondary" combustion chamber such pre-heated air entering such opening through an extension between the outlet end *"go i the primary combustion chamber and therear face of the inlet opening 14, this extension serving to insure eflicient mixing of the preheated secondary air with the burning'products' of 'partial combustiom'as'will be morefully described below. As the temperature within the secondary combustion chamber is comparatively high the interior of, the portion of the boiler fire tube 12 which constitutes the secondary cornbustion chamber, is. lined with refractory ina- 4 terial which lining is indicated generally atl'l.

such air may be supplied under pressure and ad:

mitted into the pre-heating space either through th'e'openings 4 or through another opening in" 6?: the front wall 2 of the combustion chamber which may also be constructed so as toprovide in its thickness a space for this air. By thismeans the whole or the greater partjiof the refractory lining of the primary combustionchamber will i be efficiently air-cooled.

slag orclinker into a pit or down a' chuteto a place convenient for its removalin a manner 'i-thereafterto be described. j heated secondary air with the-burning products of partial combustion the extension between the outlet end of the primary combustion -chamber and the opening 14 isprovided with a series of inwardly'and radially extending projections 19,- see Figure 2. Theseprojections in the example illustrated are formed" by using specially long wedge-shaped refractory bricks 20; which ex- "oi tend across the. secondary .air space indicated at 21, and into the passage through which the gases pass to the opening 14,

; Inlieu of induced draught for the'secondary air The lower end of the sloping bottom 5 isarranged to discharge its' accumulation of molten So as to ensure eflicientgmixing of the pre'- One of the difficulties met with in the use of apparatus for burning pulverizedfuel is that of removing'and handling the slag; The apparatus according to this invention is provided with a means, whereby the slag may be easily and successfullyremovedfrom the primary combustion chamber and subsequently handled; Such means comprise a comparatively small drain 24 located at the lower end of the inclinedbase 5 and extendirig through the floor of the combustion chamber.- ,Through this drain the molten slag is permitted to fall'down a chute 25 v and onto a :stoping and artificially cooledsurface 26.

This surface 26 is'cooled by the secondary air which is conducted through a space 2'7 on the underside of this surface 26, the space 27 being connected to the openings 4 so that the secondary air heated by contact with the underside of surface 26 passes to the space 21 adjacentto the outlet 14, By this means the molten slag within the combustionchamber is converted into small solid particlesin'which condition it is collected withinthe bottom of the chute 25 andremoved at' intervalsthrough the opening 28. It is important that the drain 24 be kept as small as possible so as to shield the surface 26 and the interior of the chute from as much as possible of the'radiant heat from the interior of the primary combustion chamber. vIf desired the surface 26 may be water cooled.

In starting up the apparatus when using pulverized fuel suflicient'air for complete combustion isadmitted with the fuel and it'has been found that more rapid heating 'upis attained if during thi'S period the fuel is ground to the finest possible powderiform. When the primary combustion chamber has been sufficiently heated the air supply is reduced and fuel ground to specification may'be used. 7 v

I claim:

"In aniapparatus for burningpulverized fuels the usual the combination of a combustion chamber, an

chamber through the upper wall thereof in a direction away from said neck'and towards the base, an outer shell surroundingsaid neck and separated from a part thereof by'a space through which secondary air passes, a main furnace chamber with which saidneck communicates in which the complete combustion of the partially burnt products discharged from said neck takes place, means for connecting the shell to the main chamber so that the air discharged from the shell passes into said main chamber, and a tubular I extensionbetween the neck and the main chamber provided with openings and with radial partic-v tions between said openings, said partitions extending into the stream of the discharged prodnote for mixing the secondary air discharged from the space between the neck and the shell with the products discharged from the neck.

ERNEST s, SUFFERN.

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