US1943949A - Furnace - Google Patents

Description

Jam. 16, WM@ T. G1. COGHLAN ET AL. m9439949 FURNACE Original Filed July 21, 1925 2 Shestsr-Sheei;l l

y m l FMT/WT Jam 16 1934' T. G. coGHLAN ET AL 1,943,949

FURNACE Original Filed July 21, 1925 2 Sheets-Sheet 2 Patented Jan. 16, 1934 UNITED STATES I.PATENT OFFICE FURNACE Thomas (G. Coghllan,

Elizabeth, and Einar A. Johnsen, deceased, late of Mountain Lakes, N. 12E., by Sigrid fl. Johnsen, executrix, Erooliriyn, N.

4 (Claims.

This application is a division of a prior application of applicants, S. N. 44,957, led July 21, 1925, on which Patent No. 1,898,479 was granted Feb. 21, 1933. The novel features of the invention will be best understood from the following description and the annexed drawings, in which is shown a selected embodiment and in which;

Fig. 1 is a vertical sectional view througha portion of a furnace and associated boiler showing the invention applied thereto;

Fig. 2 is a View on the same plane as Fig. 1, but with parts shown in section, this view being on an enlarged scale and showing certain features of the invention;

Fig. 3 is a fragmentary section on the line 3-3 of Fig. 4 illustrating one of the pipe control valves and Fig. 4 is a plan View of the valve shown in Fig. 3.

Referring now to Fig. 1,- there is shown therein a furnace having a lower combustion chamber l and an upper combustion chamber 2 connected by a restricted throat 3. In the lower part of the g chamber 1 is a fuel burning means exemplied by a chain grate 4, to which fuel is supplied from a hopper 5.

Gases from the upper chamber 2 pass upwardly through a pass 6 downwardly through a pass 7 and again upwardly through a pass 8 to an outlet 9. Extending across the threelpas'ses are water tubes 10 connected at opposite ends to headers and inclined slightly to the horizontal in a manner well known in the art. Above the passes 6 and 7 is disposed a superheater l1. After reaching the outlet 9, thegases are `conducted through an air heater 12, and the air from this heater may be supplied to the furnace in a manner more fully described in the said copending application'.

The dust contained in the gases as they pass over the boiler tubes and through the air heater may contain a considerable amount of unburned fuel, and it is desirable to return such fuel to the fuel bed. In the illustrated embodiment this is r laccomplished by providing a hopper 13 beneath the lower edge of the baffle which separates the passes 7 and 8 and another hopper 14 in the air heater. These hoppers, particularly the hopper 13, are so placed as to collect dust which may be precipitated by the gas stream when it changes "0 its direction as beneath the lower edge of ythe baffle.

Leading from the bottoms of the hoppers 13 and.l4 are pipes 15 and 16 which are joined to- K gether at the junction 17, and the dust flowing 5' through these pipes is conducted by a third pipe (ci. irc-its) 18 through an arch 19 over the lower part of the grate 4, so that it will be deposited upon the fuel bed on this grate. The fuel on the rear part of the grate is burned under the arch 20 to a great extent and, preferably, the supply of air to the lower portion of the grate is such as to cause an excess of oxygen, whereby the dust or more accurately the fuel in the dust may be thoroughly burned.

Referring now more particularly to Fig. 2, we have shown the pipe 18V as being reduced at 21 to form a throat or portion of restricted crosssectional area to increase the velocity of the stream of dust flowing therethrough. On the side of the throat away from the furnace chamber is disposed the discharge opening 22 from the pipe 17, and between this discharge opening and the throat is disposed a nozzle 23 on a pipe 24 which is connected to a suitablesource of hot air. Conveniently this air may be supplied from the air heater l2, the details of thevconnection thereto being omitted, as that is only one examy ple of a suitable source of hot air. The hot air passing through the pipe 24 is normally under pressure, as is usually the case with hot air being supplied to a combustion chamber, and its velocity is increased as' it passes through the nozzle 23, and this velocity is still further increased at the throat 21. In otherwords, the nozzle 23 forms an aspirating tube to draw the stream of dust from the discharge opening 22 and to increase its velocity and, consequently, its pressure.

The pressure by this arrangement is increased enough to overcome the pressure in the charnber l.

The pipes 1'5, 16 and 24 are preferably provided withl suitable slide valves 25, 26 and 27 respec- 'a steam boiler arranged above said combustion chamber, a dust settling chamber below a rear portion of said steam boiler in a position to receive dust separating out from the products of combustion flowing through said boiler from said combustion chamber, and means for returning collected dust from said settling chamber in suspension in an air stream to the space in lsaid combustion chamber between said arch and the rear portion of said grate.

2. A steam generator having lower and upper combustion chambers, front and rear combustion arches extending over said lower chamber and arranged to form a restricted throat between said lower and upper chambers, a traveling fuel grate in said lower chamber having its fuel feed end extending below said front arch and its ash discharge end extending below said rear arch, a steam boiler arranged above said upper chamber, a dust settling chamber below a rear portion of said steam boiler in a position to receive dust separating out from the products of combustion owing through' said boiler from said upper cornu bustion chamber, and means for returning c ollected dust from said settling chamber in suspension in an air stream to the space in said lower 'chamberbetween said rear arch and th rear portion of said grate. K

3. A steam generator having lower and upper combustion chambers, front and rear combustion arches extending over said lower chamber and arranged to form a restricted throat between said lower and upper chambers, a progressive feed fuel grate in'said-lower chamber having its fuel feed end extending below said front arch and its ash discharge end extending below said rear arch,

means for passingl air for combustion upwardlyL through the fuel bed on said grate with an excess of air above the rear portion of said grate, a steam boiler arranged above said upper chamber, a dust hopper below la rear portion of said steam boiler in a position to receive dust separating from the products of combustion flowing through said boiler from said upper combustion chamber, and means under pressure from said lower chamber said hopper to the 4space in between said rear arch and for returning collected dust the rear portion of said grate comprising a dust conduit connected to said hopper and opening to said lower chamber through said rear arch, and a iiuid ejector arranged to discharge into said conduit towards said lower chamber to convey the dust therein under an increased pressure into said lower chamber. k

4. A steam generator having lower and upper combustion chambers, a relatively short front arch and a relatively long rear combustion arch extending over said lower chamber and arranged to 4form a restricted throat between said lower and upper chambers, a chain grate in said lower chamber having its feed end extending below said front arch and its ash discharge end extending below said rear arch, means for passing air for combustion upwardly through the fuel bed on said grate with an excess of air above the rear portion of said grate, a bank of boiler tubes arranged above said upper chamber, a dust hopper below a rear portion of said tube bank in-a position to receive dust separating from the products of combustion owing through said boiler from said upper combustion chamber, means for returning the collected/dust under pressure from said hopper to the space in said lower chamber between said rear arch and the rear portion of said grate comprising a dust conduit connected to said hopper and opening to said lower chamber through said rear arch, an air ejector arranged to discharge into said conduit in the di- Y,

rection of flow, and a ow constriction in said conduit arranged to increase the pressure of the air anddust mixture before said mixture may enter said lower chamber.

THOMAS G. COGHLAN. SIGRID A. JOHNSEN, Eecutri ofthe Estate of Einar A. J ohnsen.

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