US2122390A - Steam boiler - Google Patents

Description

June 28; 1938.

J. EKLUND STEAM BOILER Filed Sept 16, 1957 3 Sheets-Sheet l ATTORNEY.

June 28, 1938. EKLUND 2,122,390

STEAM BOILER Filed Sept. 16, 1957 5 Sheets-Sheet 2 P; a 5 5 Fz'ifz. ,2?

A i 2? 2/ l mill INVENTOR.

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ATTORNEY.

vJune 28, 1938. J. EKLUND STEAM BOILER Filed Sept. 16. 1937 3 Sheets-Sheet 5 O QQQ 6 INVENT OR.

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ATTORNEY.

Patented June 28, 1938 UNITED STATES PATENT OFFICE STEAM BOILER Application September 16, 1937, Serial No. 164,120

Claims.

This invention relates to water tube boilers and more specifically to a water tube boiler designed especially for recovering in the form of saturated steam the waste heat present in gases. In other 5 words the invention relates to a boiler which is of general utility for the production of saturated steam, but which is primarily a waste heat boiler.

One of the principal objects of the invention is to provide a two-drum, four-pass, bent tube steam boiler of a design that is simple in construction and efficient in operation. A further object is the provision of a boiler having these advantages, which is also readily accessible for cleaning and for examinations and repairs which may be necessary when it is used for recovering heat from corrosive gases.

A still further object of the invention is the provision of a boiler in which heat exchange between the water tubes and the hot gases will take place under a considerable positive pressure, thereby promoting the etficiency of the heat exchange and permitting the use of lower exit temperatures.

With the above and other objects in view, the invention consists in the combination and association of parts as will be described in the following specification and claims, reference being had to the accompanying drawings, in which;

Fig. 1 is a perspective of a boiler setting and housing constituting an embodiment of the invention with the tubes omitted and parts being broken away to show the baffle structure and the path of the gases therethrough.

Fig. 2 is a transverse section, taken on the line 2-2 of Fig. 3.

Fig. 3 is a longitudinal section taken on the line 33 of Fig. 2, and

Fig. 4 is an enlarged detail of a portion of Fig. 2.

Referring more particularly to the drawings, the boiler is preferably provided with a setting which consists of vertical supports I and transverse supports 2, in the form of angle irons. Mounted in cradles 3 which are riveted to the transverse supports is a lower mud drum 4, which is preferably of welded construction and designed to withstand the operating pressures. Directly above this lower drum is an upper or steam drum 5 of similar construction and having a feed water inlet 9 and a steam outlet, both drums being provided with radial holes 6 for the reception of forward and rear banks of tubes 1 and 8.

The tubes of each bank are bent away from the center-line between the two drums to provide space for a baffle therebetween, and the ends of each tube are bent in such a manner as to enter the corresponding hole 6 in the drum in a radial direction. The upper drum 5 is thus supported at all times on the two banks of tubes, whereby no stresses due to the expansion or contraction of the tubes will be set up.

The boiler is provided with a housing which, in View of the positive pressures under which it operates, must be gas-tight. The housing Ii] therefore consists of a setting of brickwork or the like which is completely covered on its outer sides, as at ll, with a layer of mill board, preferably on the order of A, inch in thickness. This mill board is in turn covered with a layer of sheet metal sheathing I2, which is applied in upper and lower sections l3 and M, the edges of which are turned up and bolted or welded together as at l5. At the corners of the housing the metal sheathing is likewise struck up and bolted together as at l6, preferably with an asbestos gasket or liner interposed between the metal sheets to insure gas-tightness.

At the base of the housing the sheet metal sheathing is replaced by heavy bottom plates I1 and 18 of inch rolled steel. These plates are welded at their inner ends to angle irons l9 which form part of cradles 20 fitting over the ends of the lower drum 4. This forms a construction such that the boiler and the brickwork of the boiler housing are supported upon the boiler setting independently of the insulated sheet metal casing, and the latter is therefore free to expand or contract with changes of temperature without danger of warping or leakage.

At the top of the boiler, a gas-tight connection is made between the metal sheathing and the upper drum 5 in a manner somewhat similar to that which has been described for the lower drum. The upper sheathing plates iii are bolted to angle irons 22, as shown in detail in Fig. 4, and these angle irons are in turn attached to the upper drum 5 by stud bolts 23 and by asbestos packing strips between the metal surfaces on each face of the angle irons. The metal sheathing at the top and sides of the housing is therefore supported along its bottom edges by the metal plates i1 and I8 and is attached at its top to the upper drum 5 by joints which permit vertical expansion and contraction, so that the sheathing merely surrounds the brickwork li'l and is free to creep along it.

Within the boiler housing, and supported by the walls thereof, is a baffle structure which, in combination with a gas inlet and a gas outlet, is adapted to direct the flow of gases in such a sage on the opposite side of the transverse baflie the gas inlet passage, then across the top of the manner that an extended travel of hot gases along and across the boiler tubes is obtained. For this purpose a longitudinal bafiie 25 is mounted in the space provided between the tube banks, as best shown in Fig. 2. This b-aifle extends from the-front wall to the rear wall of the boiler housing, and is mounted and supported in these walls. Vertically it extends from the lower drum to a level somewhat below the lower surface of the upper drum, thus providing a space for the passage of hot gases across the boiler tubes at their upper ends. It will be seen that this longitudinal baffle 25 divides the boiler housing into forward and rear sections 26 and 21 which are in communication along its entire length.

As is shown in Fig. 3, the boiler tubes of the rear tube bank 8 are divided into two sections 30 and 3 l, and the same is true of the forward tube bank I. Between these sections of tube banks forward and rear transverse baffles 32 are located, these being shown as the forward and rear parts of a single unitary baiile structure. These bafiles extend entirely across the upper part of the boiler housing, and the forward bafiie also extends the full height of the boiler in the forward section 26. The rear transverse baffle 32, however. terminates in a cast iron lintel 33 mounted across the rear section 27 and secured in the brickwork at either side a substantial distance above the lower drum 4, whereby a flow of hot gases will be directed along the rear tube bank 8 at its lower end.

The intersecting transverse and longitudinal baffles therefore divide the boiler housing into four communicating gas passages, each containing one section of one bank of tubes.

A gas inlet 35 is provided preferably in the lower part of the frontwall of one of the forward sections 26, and a smaller gas outlet passage 36 is provided, preferably at the lower part of the front wall of the furnace, in the other front pas- 32. The gas inlet and gas outlet passages are completely closed off from each other by the forward transverse baffle 32 and thus the entering gases must pass upwardly along the tubes in bafile 25 and downwardly along the tubes in the rear gas passage on the same side of the rear transverse baffle 32, then under the lintel 33 longitudinally of the rear tube bank, then upwardly in the opposite rear gas passage, again over the top of the longitudinal baflie 25 and finallydownwardly in the front gas passage and out through the outlet 36. Since. this outlet 36 is much smaller than the inlet 35, and preferably of the order of 0.6 of its area, a considerable back pressure is created which greatly improves the heat transfer efiiciency of the furnace. In. the installation shown, and using gas speeds designed for maximum efficienoy, the gas pressure within the boiler will be on the order of 2 lb. gage.

As has been stated, the above described boiler. is designed primarily for use in recovering the waste heat in industrial gases. For these purposes, a boiler must frequently operate with gases of much lower temperature than those found in ordinary boiler plant practice; for example, gases from roasting kilns such as in the roasting of pyrites and the like may reach the boiler at temperatures of 800-1200" F. Gases from sulfur burners, on the other hand, may have temperatures as high as 2000 and other industrial gases may vary between these limits. It is an advantage of the four-pass, bent-tube boiler that has -been described that it will successfully hanthereof, it is understood that variations and substitutions of the details of this modification may be resorted to within the scope of the appended claims.

What I claim is:

1. In. a-boiler, in combination, an upper drum, a lower drum, two banks of tubes connecting said upper and lower drums, each bank being divided longitudinally into a plurality of sections, the tubes of each bank being bent away fromthe center line between the drums to provide .a space for a bafiie, a longitudinal baffle located in the space between the tubes and adapted to direct a flow of hot gases across the tubes at their upper ends, and transverse bafiles between the sections of tube banks on each side of said longitudinal baffle, the transverse baffle on one side being adapted to separate the gases entering from those leaving the boiler housing, andthe transverse baffle on. the other side beingadapted todirect'a flow of hot gases along the tube bank on that side at its lower end, whereby four separate passes over the tubes are obtained in series.

2. In awaste heat boiler, in combination, a boiler housing, upper and lower drums extending longitudinally of said housing, a longitudinal baffle extending from the lower drum to a level below the upper drum and dividing the boiler housing into communicating forward and rear sections, banks of tubes connecting the upper and lower drums on each side of said baflle, a transverse baiile extending completely across said forward section and dividing it into gas inlet and gas outlet passages,, and a transverse baflieextending across said rear section and terminating above said lowerdrum to divide it into communicating gas downflow and gas upflow passages.

.3. In a boiler, in combination, a boiler housing, upper and lower drums extending longitudinally of said housing, two banks of tubes connecting said upper and lower drums, each bank being divided longitudinally into a plurality of sections. the tubes of each bank being bent away from the center line between the drums to provide space for a baiile, a longitudinal bafile located in the space between the tubes and adapted to direct a flow of hot gases'across the tubes adjacent the upper drum, an inlet and an outlet for hot gases in one side wallof the boiler housing, and a transverse baflie located between adjacent sections of the bank of tubes and completely closing off the space between the gas inlet and the gas outlet on the gas inlet side of the longitudinal bafiie but terminating above the lower drum on theopposite side to direct a flow of gases longitudinally of the bank of tubes on this side, whereby four separate passes of hot gases over the tubes are obtained in series.

4. In a waste heat boiler, in combination, a,

boiler housing, upper andlower drums extending longitudinally of said housing, a longitudinal the lower drum to a level below the upper drum and dividing the boiler housing into communicating forward and rear sections, banks of tubes connecting the upper and lower drums on each side of said baffle, an inlet and an outlet for hot gases in the forward section, the outlet being substantially smaller than the inlet, a transverse bafiie extending completely across said forward section cutting oii the inlet from the outlet and a transverse baffle in said rear section terminating above said lower drum and permitting the passage. of gases thereunder.

5. In a boiler, in combination, a boiler setting comprising a base including a pair of vertical and transverse supports, a lower drum mounted on said transverse supports, an upper drum directly above said lower drum, two banks of tubes supporting said upper drum and connecting it with said lower drum, the tubes of each bank being bent away from the center line between the drums to provide a space for a baffle, a boiler housing supported on said vertical supports and including a top fitting around said upper drum and front and rear walls parallel to the plane of said drums, a longitudinal baffle in said space between the tube banks extending from the lower drum to a level below the upper drum and dividing the boiler housing into forward and rear sections, a gas inlet at one side of the forward section, a gas outlet at the other side of the forward section, a transverse bafiie across the forward section separating the gas inlet from the gas outlet, and a transverse baiile across the rear section terminating above said lower drum and permitting the passage of gases thereunder. JOEL EKLUND.

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