US2250849A - Radiant superheater - Google Patents

Description

Patented July 29, 1941 RADIANT SUPERHEATER Wilfred R-(Wood, New York, N. Y., assignor to Combustion Engineering Company, Inc.', New

. York, N. Y.

Application October 28, 1937, Serial No. 171,451)

3 Claims.

The present invention relates to steam superheaters of the so-called radiant type which are located adjacent to the walls of the furnace and receive the greatest part of their heat by direct radiation. The advantages of this type of superheater have been recognized in the past but the difficulties resulting from theextremely severe conditions under which they operate have militated against their adoption. Attempts have been made in the past to furnish some protection to such superheaters against the intense radiant heat to which they are exposed. Thus the .use of refractories has been proposed which were supposed to shade the superheater elements more or less againstthe intense radiation while in other ,cases spaced water-cooled tubes have been interposed between the superheater and the furnace, which not only partly shaded the superheater tubes, but which by their proximity to the superheater tubes resulted in cooling them somewhat.

The invention of this application refers more specificallyto superheaters' of the kind referred to above, when installed in water-cooled furnaces with so-called tangential firing. In suchfiring, which applies to oil and gas as well as to pulverized coal, the fuel is delivered through a plurality of the fact that this more rapid cooling makes it possible to confine the water-cooling of the furnace walls to the lower portion of the furnace, their upper portion. presenting a safe region for radiant superheater surface, the temperature of the gases having been sufficiently reduced by the more rapid cooling due to tangential firing.

The invention is illustrated in the drawing filed herewith in which Fig. 1 represents a vertical section through a boiler embodying my invention, and Fig. 2 is a section on line 22 of Fig. l. The setting enclosing the furnace and boiler is shown at I. The boiler proper comprises a bank of tubes 2 which is somewhat inclined from the horizontal, the ends of the'tubes being connected respectively to a lower set of headers 3 and an upper set of headers 4. A drum 5 placed vertically above the set of headers '3 is connected q scribed below, is combined with a convection to this set bythe downcomer tubes '6 and to the set of headers 4 by the risers l. i

In the particular form of the invention. illustrated in the drawing and described herein; the radiant type of superheater, which will be desuperheater section 8 located above the bank 2. Battling 9 directs the gases over the bank 2, then over the superheater section 8 to the downward .pass It! and so to the stack connection ll. Pref-- erably a by-pass I2 is provided for purposesof regulating the degree of superheat. This by-pass permits gases to pass directlyfrom the bank of tubes to the down-pass Hl'without striking thev setting. They are connected at their lower endsto headers lE-IE and at their upper ends'to" The water for these tubes is;

headers I 6l 6.

Supplied in any preferred manner. In the case illustrated it is supplied to thelower headers 15 from the auxiliary header ll which receives such water from the transverse header l8 by means;

of the set of tubes IS. The transverse header I8 in turn receives itthrough nippled connections from the set of headers 3 The upper headers l6 are connected in any; F preferred manner and to any preferred place to deliver their mixture ofsteam and water to the main boiler. .In theform illustrated there are connections from each of these headers to the drum 5. The connections, for example, from the left header IE to the drum 5 are effected by means of the riser tubes 20, andthe upper header l6 at the right is connected to drum 5 by a set of tubes 2|. The connections from the header It on the farther side of the furnace 'are effected by means of connecting tubes 22-22 which extend upwardly along the side of the furnace walls and then fan out in wardl'y in a horizontal plane and are bent toward the drum 5 to which they are connected in a horizontal line. The connections from the Corresponding header IE on the fourth side, which does not appear in the drawing, are made in a similar manner.

The burners for this, furnace are shown at 23-23. In the particular installation shown r or ies] they are located at the corners although this is not essential. The particular form of burner used is also immaterial. They must, however, be so placed that their axial lines are directed tangentially to an imaginary horizontal circle. This will result in a rotary movement of the gases in the furnace as they progress upwardly on their way toward the boiler. This rotary movement causes the gases to come into more intimate contact with the water tubes lining the furnace walls and thereby to become more rapidly cooled than they would were it not for this rotary motion.

The upper portion of the furnace walls is not lined with water tubes but is reserved for the radiant superheater. This'radiant superheater is in general similar in structure to the water tube lining described above, i. e. the tubular superheater elements lie in close proximity to the wall and are connected to upper and lower headers. It is a matter of choice how the flow of the steam through these four sections lining the four walls is directed. Preferably the steam i caused to flow through the four sections in sequence, In the'form illustrated, for example,

the tubes 24 convey the steam from the drum to the header 25. From this header the superheater'elements 26 carry it to the lower header 2'1. Preferably one end of this header is connected to a lower header in one of the side walls and the corresponding upper header is next connected to the upper header of the left wall.

The lower header of this left wall in turn is" which the superheater elements lining the upper furnace walls are connected may be varied and in fact the entire arrangement of the superheater elements may be varied from that shown. It is not, for example, necessary that the tubular superheater elements extend vertically. My invention applies equally to other dispositions of these elements. FurthermoreQthe furnace evidently does not need to be arranged so' the gases flow vertically, but may extendlhorizontally, for example with gas flow spiralling around its-horizontal axis.

Other variations can in practice be introduced without departing from the spirit of the invention, the essential feature of the invention being the use of the tangential injection of the fuel near one end of the furnace in combination with the water cooling of the part of the furnace Walls adjacent to such end and the location of the radiant superheater at the remaining portions of these walls.

What I claim is:

1. In a boiler, the combination of a furnace, burners in the lower part of the furnace arranged to inject the fuel and air tangentially to an imaginary horizontal circle thereby causing the gases in the furnace to rotate in a horizontal plane substantially coincident with the axes of the burners and about a vertical axisas'they move upward, vertically extending water tubes lining" the lower portions of the furnace walls and so located as to be swept by the gases in their rotary movement, and vertically' extending steam superheater tubes lining the upper portions of the furnace walls;

2. Ina boiler, the combination of a furnace,

Water tubes lining the lowerpart of each of the' furnace walls, steam superheater tubes liningthe remaining portions of the furnace walls,

and burners at'the lower part of the furnace arranged'to inject fuel and airtangentially to brought into good heat transferring relation with the water tubes, whereby" the temperature of the 'gases is substantially uniform all around the furnace at any. given leveland is reducedsufficiently to make a safe heating medium'rforthe superheater in the" location stated.

3. In a furnace having burners positioned to inject fuel and air into'the furnace near one end and arranged so as to produce a-rotating movement and turbulent mixing of gases-within the furnace about 'its longitudinal axis and in a plane substantially coincident with theburner axes, thereby forming a local zone of relatively high rate of combustion and resultant relatively high temperature of combustion; water tubeson all furnace walls normal to said plane and covering the entire surface areas immediately adjacent said zone so as to be scrubbed by the gases in their rotating movement and subjected to the radiant heat'of said high temperature of combustion; and superheater tubes on furnace wall portions located beyond said water tubes in the direction of gas flow.

WILFRED R. WOOD.

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