US2520692A

US2520692A - Gas and air mixing device

Info

Publication number: US2520692A
Application number: US647666A
Authority: US
Inventors: Elno M Powell; Virginius Z Caracristi
Original assignee: Combustion Engineering Superheater Inc
Current assignee: Combustion Engineering Inc
Priority date: 1946-02-15
Filing date: 1946-02-15
Publication date: 1950-08-29
Anticipated expiration: 1967-08-29

Description

Aug. 29, 1950` E. M. POWELL ErAL GAS AND AIR MIXING DEVICE Filed Feb. l5, 1946 Patented Aug. 29, 1950 UNITED STATES PATENTv OFFICE eas vAND siue DEVICE Elno .M. Powell, Chappaqum and Vrgnius Z'.

Garacristi, Bronxville, N. Y., assigmrs, to Ccmbustion Engineering-Superheater, 1nd a corporation of kDelaware Application February 15, 194,6, Seri-al No. 647,666 t 5v Claims. i

This invention relates to apparatus for 'mixing uids of different temperatures and particularly for mixing gases taken directly from a furnace with a cooler gas.

Heretoiore apparatus for mixing gases'taken directly from a furnace with air required the use ofa considerable amount of heat resisting alloys and brick lined ducts Which Were both cumbersome and expensive. It is an object of this invention to provide improved means for mixing hot and cold fluids.

Figure 1 is a sectional elevation of the improved gas mixing apparatus, the section being .taken on line Iwlin Figure 2..

Figure 2 is a View taken on line 2-2 of Figurey 1.

A conduit I9 Within refractory lined Wall. conducts hot gases directly from a furnace indicated fragmentarily at II .to a plenum chamber I2 comprising ay side plate I3 mounted on the end Wall of conduit. Ill, four sides Ill-and a. front I5. An opening f6 is provided in one side f4 in conimunication with an air duct I?. Projecting centrally into plenum chamber YIi: is the open ended inlet I8 of a duct I9'. The inlet. end t8 of the duct is preferably made cylindrical and is open, at one end to form an inlet 2o.'. Gutside plenum chamberl I2 duct I9 is. formed into a bend 2l which terminates in an outlet 22. Concentric with inletl l'S is a pipe. 23 which passesv through a sleeve 24 mounted in the outer Wall of duct I9;` The end of said pipe 23 Acarries a valve member 25 in the nature of an adjustable baffle. Pipe 23 is supported adjacent the valve member 25 by means of sleeve 26 and spider 2'! which centers it in the cylindrical end portion I8 of conduit I9. Member 25 is provided with an inclined face 2t shaped to nt al valve seat 29 mounted on wall I3 of the plenum chamber I2 at the end of the gas inlet conduit I0. The pipe 23 is provided with means outside of duct I9 for seating or withdrawing the valve member 25 with respect tothe valve seat. 29. For example, threads 3c onthe end of pipe 23 are engaged by threads Within aV` hand Wheel 3i,V the hand Wheel being retained from axial movement by a collar 32 fastened to sleeve 24.

In operation, air, either preheated or cold, is introduced through air duct I 'l (either under positive pressure or by induced draft) into the plenum chamber I2 where it is distributed substanti-ally uniformly around the circumference of the inlet end i8 of duct I9, this distribution being caused by the restriction of the passage around inlet Wall I8 as Well as by a 180 de- 2 grec turn around into the inlet 20 Vto .duct I9. The airis thus directed as: a relatively thin sheet past the outside surface of valve; `seat 29:.. The

gas `enters through conduitclil at: a very highy temperature, preierably 'directly trom the furnace II, and is deflected by the valve member 25, which when open actsy as a baffle, outwardly' a thin sheet into the air stream which enters duct t9. Because of the relatively thin layers and uniform distribution of the two fluids a thorough and rapid mixing takes place. Thereafter the mixture of air and gasv at a substantially reduced temperature: due to their admixture passes through duct i9 tothe. point of' use. The. central pipe 23 which carries the valve'member 25 may be left. open to the atmosphere so that cold air may pass therethrough to the face of the member 25 and thence radially over that face to there mix with the gas coming from the gas inleti..

ByY introducing the gas. from furnace Il into the center of the air stream no metal is subjected to temperatures higher than that of theultimate mixture, except the valve member 25v and seat 29. Valve seat 2.9- is cooled by air from inlet I6 sweeping over its outer side, while the member 25 is partly cooled by air from pipe 23 sweeping across its face. It ha been found that no insulation is required inside of the duct I9 for protection of the metal against over heating. All of the sleeves` or bearings which supportpipe 23- are located in relatively coolzones. The. pipe 23 provides easy access the the furnace opening or. conduit W, for inspection and cleaning. The

f quantity ci alloy material required to resist high temperaturesis limited to the valve member 25 and valve seat 2-9. 'By making the parts. cylindrical or conical-ly formed they may be kept of rel-ativeiy light weight to withstand explosion pressures'. The adjustment; of'. pipe 23 provided by the hand' Wheel M permits the'valcze member 25' to be moved back and forth so as to' control the amount of gas flow. c

YIn a typical application of the mixer apparatus hereL disclosed, the heated air from outlet conduit 22 is drawn into a fuel pulverizing millinot shown) under suction created -by a fan in that mill system which maintains the interior of conduit 22 under a, given negative pressure; the air thus drawn through the mixer apparatus by the named suction may come into inlet conduit I1 directly from the furnace room or from an air heater (not shown) attached to inlet I'I or from some other source of heated air whose pressure is higher than that maintained in outlet conduit .thatoutlet conduit 22 supplies.

Y wall thereof.

22; and the furnace Il communicating with hot gas conduit I normally operates under a slight negative pressure (created by the stack draft) which is, however, not as far below atmospheric as that in the interior of conduit 22.

Under all operating conduitsr of this novel mixer-apparatus, the given negativepressurefor suction` in outlet conduit 22 draws air` from. inlet I'I into the open end i8 of mixer duct I 9 and thence downwardly through elbow 2| into outlet:

conduit 22. This is true even though valve member may be full;7 closed (to the right) against seat 29.

nace Il; the left end of pipe 23 being open to the atmosphere the negative pressure within furnace II then draws unheated air to theyright through the pipe and into the furnace (without damage to any of the parts).

The'full closure'of Valve member 25 .above describedis sometimes' found' desirable when inlet conduit'l'l gets vits air from heater apparatus (not shown) which under certain yconditions itself raises the air temperature highY enough for properoperationof the mill or other equipment Usually, however, the air flowing through mixerduct i9 fwill require some supplemental heating; this is .provided by adjustably opening' v(tothe left) valve member 25in the manner aforesaid to allow'ilow from furnace Il of hot gas into mixer duct I9 in suicient quantity to raise to the'elevated value desired the .temperature of the air VVleaving the apparatus by way of outlet 22.

What we claim is:

l. Means for Ymixing hot and relatively cold gases comprising walls enclosing a chamber having an inlet in one wall for cold gases; a conduit connected into the chamber through a contiguous wall for the introduction of hot gases; a member aligned withsaid conduit and spaced from the outletendthereof so as to dene an annular passage for the hotgases between the face of the member and the end of theconduit, an offtake duct surrounding the annular passage .with the wall of its inlet end spaced .from the facing wall surfaces of the chamber to pro- '.videa cold gas passage therearound, said duct passing out of the cold gascharnber through a 2. Means for mixing hot and relatively cold gases comprising walls enclosing a chamber having an inlet in one wall for cold gasesyan open ended conduit having a valve seat atits open end extending into the chamber for the introduction'of hot gases; a disc movable axiallyof said conduit to and from said seat; means for controllably spacing the disc from` the seat thereby defining an annular passage for the Vhot gases between the disc and the seat; an oitake duct i surrounding the-annular passage with the wall of-its inlet Vend of said duct being spaced from the facing wall surfaces of the chamber for pro- Such full closure shuts off all. outward flow through conduit-l 0 of hot gas from fur- 3. Means for mixing hot and cold gases comprising walls enclosing a cold gas chamber having an inlet in one wall for cold gases, a conduit 'extending into the chamber for the introduction of hot gases, an extension on said conduit flaring in the direction of gas flow to form a seat, a cooperatingV disc having a bevelled periphery parallel tothe flare of said seat; .means for controllably spacing thedisc from the seat thereby defining an annularV passage for the hot gases between the face of the disc and the end of the conduit, an oitake duct surrounding the annular passage with the wall of its inlet end spaced from the .facing Walls of the chamber to provide a cold gas passage therearound, said duct passing out of the gas chamber through a wall thereof.

L4. Means for mixing hot and relatively cold gases comprising walls enclosing a cold gas chamber having an inlet in one wall for cold gases, a conduit connected into the chamber through a Vcontiguous wall for the introduction of hot gases, a member aligned with the conduit and spaced from the outlet end thereof for defining an annular passage for the hot gases between the face of the member and the end ofV the conduit,

' a pipe centrallyfsupporting and spacing the viding a cold gas passage therearound, said duct thereof.

member from the conduit outlet and arranged Vto admit cold gases onto the face Vof said member opposite the conduit, an oitake duct surrounding the annular passage, the inlet end of which is spaced from the adjacent wall of the chamber providing a coldgas passage therearound, said duct passing through thecold gas chamber and thence out through a wall thereof. 5. Means for mixing Ahot'and relatively cold gases comprising walls enclosing a cold gas chamber having an inlet in one wall for cold gases, a conduit connected into the chamber through a contiguous wall for introduction of hot gases, a member aligned with the conduit and spaced from the outlet end thereof for defining an annular passage for the hot gases between the face of the member and the end of the conduit, a pipe centrally supportingand spacing said member from the conduit outlet and arranged to admit cold air surrounding the chamber onto the face of said member opposite the conduit, an offtake duct surrounding the annular passage the inlet end of which is spaced from the adjacent wall of the chamber providing a cold gas passage therearound, said duct passing through the cold gas chamber and thence out through a wall thereof.

ELNO M. POWELL. I VIRGINIUS Z. CARACRISTI.

REFERENCES CITED UNITED STATES PATENTS Number Name Y Date 393,332 Heatley Q ,f Nov. 20,1888 1,8631391 YBluemel ;June 14, 1932 2,164,954

Stephens i-- July 4, `1939