The present invention relates to boiler amplifiers or devices for increasing the capacity of steam boilers. More particularly, the boiler amplifier of the invention is adapted to increase the steam generating capacity of a boiler and employs a forced circulation system, water from the boiler drums being pumped under constant pressure into a system of tubes of small diameter, and after being heated by fires within the circuit of the tubes is returned to the drums mainly as steam. By various structural means within the scope of the invention, the flow within the tube system of the device is prevented from expanding into steam and forming steam pockets until it is returned to the drum, at which point the steam and hot water are permitted to separate.
The boiler amplifier is attached to the boiler and is an extension thereof and its combustion chamber communicates with the combustion chamber of the boiler through an opening in the walls of the boiler. It is thus outside the boiler proper but the gases of combustion from the device are permitted to flow into the combustion chamber of the boiler.
The amplifier of the invention has for its aim the more even use of heat and a greater recovery than is possible in conventional types of boilers and auxiliary apparatus at present in use with such boilers. Many attempts have been made and considerable work has been done in connection with heat recovery as applied to steam boilers. To this end many appliances have been designed such as steam superheaters, desuperheaters, air pre-heaters, appliances for utilizing the passing of gases, etc. Most of these applications, however, are made in connection with the final stage of the boiler combustion process-that is, the final gas outlet of the boiler between the boiler and the smoke stack.
The amplifier of the present invention, however, effects heat recovery at the furnace end of the boiler. The instrumentality for accomplishing this end is a boiler extension which comprises a water walled furnace in which the combustion takes place more or less centrally within the ambit of tubes which wholly or partially surround the combustion chamber. If the fuel utilized is oil or powdered coal, the tubes will form preferably a cylindrical enclosure in which the fires are centered. This cylinder may be, for in- i stance, approximately six feet in diameter and may be constructed for best effects of seamless steel tubes having a diameter of from one inch to one and a quarter inches. These tubes are bent into a circular section and will be secured I at top and bottom to headers, the water entering the lower header, circulating around both sides of the circular furnace and being discharged through the top header. The length of this furnace may be approximately eight feet. It is set in front of an opening into the firing space of the boiler which may be of any conventional type, and one end of the cylindrical tube system is open and communicates with the boiler furnace space. It is preferably surrounded by a refractory covering, such as fire brick, and finished with heat insulation material, such as masonry or metal casing, so as to form a Dutch oven effect.The fuel bed or cone is thus moved from its accepted location within the combustion chamber of the boiler proper to a position outside the boiler and within the water walled furnace extension of the amplifier of this invention. The gases resulting from the combustion of fuel in the amplifier, however, pass through the open end of the amplifier into the main boiler combustion chamber and thence through the usual boiler gas passage to the smoke stack.
In this amplifier I make use of the principle of forced circulation, pumping the water from the boiler drum or drums and forcing it through the water walled furnace extension or amplifier where it collects its heat from the fuel being burned. It is then carried by the action of the so pumping in the form of water and steam mixed back to the boiler drum where it is permitted to expand and separate steam from water. Controls are used such as orifice plates or other pressure drop devices to control the flow of water and prevent expansion' before entering the boiler steam drums.
In the past, attempts more or less successful have been made to construct boiler amplifiers or boosters as they were called. Generally, these consisted of tubes wrapped in a single layer helix without headers to provide for cleaning. It is also the case that boosters of this general type have been made with a square section having headers located in an upper corner and a lower 14 corner. .Such a construction accordingly consisted of two perpendicular rows of tubes and two horizontal rows of tubes through which the water was forced.
In such a construction the water forced into 0 the tube system must travel the whole length of the header which together with the tubing forms a single complete unit. The result is an unequal pressure of water within the various tubes permitting the formation of steam pockets. There s is consequently difficulty in draining and cleaning the tubes and unevenly distributed strains and stresses result from violent temperature hanges.
In the amplifier of the present invention, however, the tube system is not a single continuous unit such as that just referred to. It is, in fact, a plurality of short units or sections, each having an inlet header at the bottom and an outlet header at the tbp and each having a plurality of tubes of curved contour embracing the fires. Greater or less capacity can be had by adding or subtracting scctions, and, by means of appropriate valves, one or more sections may be cut out for cleaning or repair. Thus, cleaning or draining is facilitated and blowing down of any section may be effected by cutting out one section at a time and opening a valve provided for that hpurpose. It is an object of the present invention to provide a boiler amplifier comprising a system of tubes which more ew ciently generate steam and which greatly increases the capacity of a boiler with which it is used.
It is a further object to provide a boiler amplifier the tube units of which are constructed in sections of convenient size and capacity so that sections can be added or removed to increase or decrease its capacity.
It is a further object to provide an amplifier thatcan be constructed, stress relieved and tested in a factory, and taken to the ob site. In the past such furnace extensions or amplifiers had to be constructed on the premises as they are of one-piece construction and could not be taken through ordinary door openings. The sectional construction of the amplifier of the present invention permits it to be taken section by section through ordinary door openings.
The invention will be more clearly understood by reference to the drawings in whichFig. 1 represents a front elevation of the boiler amplifier of the invention, together with its connections with the drums of the boiler; pig. 2 is a side elevation of the same with the boiler and a boiler drum partially broken away; Fig. 3 is a plan view of the boiler amplifier and the boiler; Fig. 4 isg a sectio o onl elevation of the boiler amplifler on the lines 4-4 of Fig. 2; ig. 5 is a side elevation of the amplifier tube assembly showing the sectional construction; 4g. 6 is a detail showing the construction and mounting of the orifice plates; Fg. 7 illustrates the construction of the end of a header; Fig. 8 is a section of a header along the lines - of Fig. 7 showing the method of joining the amplifier tubes to the header; Fig. 9 is a modification of the construction shown in Fig. 8; Fig. 10 is a modified construction of the amplifler shown in Fig. 4 but having two headers at the bottom and two headers at the top; Fig. 11 is a plan view and Fig. 12 a side elevation showing a method of construction of the amplifier of the invention in which the risers cornmunicate directly with the drum of the boiler without any intervening header; Fig. 13 is a sectional elevation along the line 13--13 of the coal stoked amplifier which is shown in Fig. 14; and Fig. 14 is a sectional elevation along the line 14-I4 of Fig. 13 with the tube sections partially connects with the drums I, 2 and 3, within the Referring now to the drawings, Fig, 1 shQws a front elevation of a boiler of any conventional type having, in this instance, three drums indicated at I, 2 and 3. The boiler amplifier device t of the invention is shown placed in front of 6 the boiler. The heating unit ,g illustrated as an oil burning unit, feeds into the center of the combustion chamber around which the tubes I of the device are indicated in dotted line. From the drum a a pipe 1 leads to a pump Io and subsidiary pipes 8 and 3 connect with pipe 1 at $a and 9a and thus through pipe 1 with pump i I.
Pump 10 delivers the water from pipe 1 through pipe II to the tube sections, five of which are indicated at 6, forming one complete unit. The number of such sections may, of course, be greater ounte beter less than this number according to the apcity ncrease desired or required. Shut off valves 2 and safety valves Ic are placed in the connections of wn nthe pump i and the sections 6 and a pressure gauge i4 is also mounted in pipe in. The heated water passes from the tube sections 6 through the top headers II, riser pipes 16, through orifice plates It, 8ha, ro b, f e and tid, header 17, and back to the boiler drums I, 2 and 3. It will be seen that header 1I is a manifold header communicating on one side with each tube section top header 15 through riser pipes 16 and on the other side with each boiler \ drum through a separate pipe connection.
A valve 19, 9a m b, tio c and m 19 is mounted between the orifice plates II and the header aw and pressure gauges 20, 20a, 20b, 2 and 20dc are mounted between the riser pipes wi and the orifice plates i8.
The detaied construction of the tube sections of the invention is shown in Fg. 4 which is a front elevation thereof and in Fig. 5 which is a side elevation with the walls broken away. It will be seen th the inner side walls 21 are s of refractory 0 material, such as fire brick, and the outer walls 22 of heat insulation material. An arch 23 suspended from I-beams 24 forms the roof of the combustion chamber and is constructed in manner 2imilar to the walls. The floors also have the same construction. However, where the tubes enter the combustion chamber, it is entirely of refractory material, as shown at 25. The drawings Fig. 4 and Fig. 5 show a preferred construction of the tubes of the device. It will be noted that the pipe I which, as above stated, leads from the pump 10, connects with the joint 26 which in turn connects with the bottom header 21 in such a manner that the water from pipe I I is directed into the header in alignment with i the tubes which meet the header in a somewhat vertical position. It will also be seen from Fig. 5 that the tubes 6 are divided into sections, each section having an individual bottom header 21 and a top header 15, the former receiving the flow from pipe 11 and the top discharging into the riser or pipe 16. The joint 26 connects with one end of the header 21 and at the discharge end of the section the riser 16 connects with the top header 15 at the most remote opposite end from the inlet in bottom header 21. This assures uniformity of circulation within the section.
The arrangement of the risers 16 will be seen from Figs. 2 and 3, Fig. 2 being a side elevation of the amplifier and Fig. 3 a view from above. It will be noted that each section of the amplifier has a top header 15 and that the risers 16 rise from these headers 15, of which five are shown, and connect with the header I1 which in turn boiler. These connections (as shown in Figs. 1, 2 and 3) each include the pressure gauges 20, 20a, 20b, 20c and 20d, the orifice plates 18, lla, 1ib, 18c and IOd, and the valves 19, 19a, 19b, Ic and I.d.
The construction and mounting of the orifice plate 18 is illustrated in Fig. 6 in which it is seen that it is installed between the flanged edges 28 and 29 of the pipes 30 and 31. Bolts 32 clamp the flanged edges of the pipes tightly together and hold the orifice plate in place. This enables in case of necessity the removal and replacement of the orifice plates by simply loosening a few of the bolts, slipping out the orifice plate, replacing it and then tightening the bolts once more after the new orifice plate is installed.
It will be observed that the opening of the orifice plate is preferably countersunk 6r flared with the small diameter side of the opening towards the risers 16 and the large diameter side of the opening towards the drums 1, 2 and 3, thus allowing for rapid expansion and separation of steam and water in the boiler.
In Fg. 7 is shown a construction of the header and illustrating the construction of any of the headers 15 or 27. It will be observed that the end of the header is stopped or plugged by the plate 36 which is welded in by a mitered joint.
Fig. 8 is a section of the header of Fig. 7 taken on the lines 8-8, and shows the method of joining the tubes of the amplifier system 6 to the header.
Fig. 9 illustrates a modification of Fig. 8 consisting in the provision of collars 37 which are welded to the header and the tubes 6 are welded to the collar. This has the advantage over the connection illustrated in Fig. 8, in which the tubes 6 are welded directly to the header, in that it facilitates annealing and stress relieving of the welded joint.
It is sometimes desirable to provide two headers at the bottom and two at the top of the tube system of the amplifier, and such a construction is shown in Fig. 10. In this construction the pipe II leads the water from the pump 10 (not shown in the figure) through the connections 26-26 into the headers 27-27, the tube system 6 and top headers 15-15, then through pipes 16a and 16b to pipe' lS, whence it is returned to the boiler drums in the manner previously described.
Figs. 11 and 12 illustrate a construction in which the riser pipes 16 connect directly with the boiler drum I without an intervening header.
Fig. 11 is a plan view of this construction and Fig. 12 a side elevation.
Fig. 13 shows a sectional elevation of a coal stoked amplifier of the invention. Due to the necessity of providing space for the grates in the combustion area of the amplifier, the lower ends of the tubes are spread apart and two headers 27, 27, are provided at the inlet side of the tube system which is curved above the fires to the junction with the single top or outlet header 15.
Fig. 14 is a side elevation of a coal stoked amplifier showing the stoker 38 and the tube system 6, each section of the tube system being provided with top headers 15 and bottom headers 27 as in Fig. 13.
The walls of the amplifier combustion chamber may conveniently be built in sections corresponding to the sections of the tube system of the amplifier and these sections are indicated in Fig. 2 at 39, 40, 41, 42 and 43. It is thus possible, where it is desired, to obtain access to the tube system or to remove a single section thereof, to break out a single section of wall, disconnect the tube section and remove it through the side of the amplifier structure. Furthermore, as shown in Figs. 13 and 14, a bridge wall 44 may, if desired, be used where the amplifier is stoked.
The operation of the boiler amplifier is as follows: The pipes 7, 8 and 9 connect with the boiler drums 1, 2 and 3 below the water level in the drums. As seen in Figs. 1 and 2, the boiler is represented as of a conventional type comprising one or more drums 1, 2 and 3, having a natural circulation. The pipes 8 and 9 connect with pipe 7 which in turn connects with the pump 10.
The pump 10 draws the water down from the boiler drums and forces it through the pipe II to the header 27, then up through the tubes of the amplifier system 6, and through the headers 15, pipes 16, orifice plates 18, 18a, 18b, 18c and 18d (shown in Fig. 3), and thence into header 17, from which it drops back into the drums as separated steam and water. Due to the control exerted by the pressure provided by the pump 10 and the restriction effected by the orifice plates 18, the water and steam flowing through the system cannot separate until they have passed into the boiler drum where there is sufficient space for expansion. A higher pressure is maintained in the amplifier system than in the boiler drums; for example, if the pressure in the boiler drums is 150 lbs., the pressure in the amplifier should be approximately 160 lbs. or higher. :)o At the outlet of the pipe into the boiler drum a baffle 33 is placed which assists'in separation of the steam and water. For purposes of draining and cleaning the tube system of the amplifier, a blow-off valve 34 is provided below the :v5 bottom header of each section of the tube system. When it is desired to blow down a section, the inlet shut off valve 12 is closed and then the blow-off valve 34 is opened, with the result that the water and steam are forced by steam pressure from the top portion of the amplifier tube system and out through the blow-off valve in a direction opposite to normal circulation. A back wash blow down effect is thus produced.
In the form of the invention where furnace coal is stoked in to provide the heat for the amplifier, the tubes are arranged to accommodate the grates 35, and to this end the tubes of the amplifier diverge from the circular formation shown in Fig. 4. As will be seen in Fig. 13 the jo tubes separate at the bottom and the header 27 is duplicated on either side as shown at 27, 27 in Fig. 13. The pump connections are, however, the same and the pipe system of the amplifier is constructed in sections as shown in Fig. 14.
o5 The operation of the amplifier is the same as in the circular construction which is employed when oil or powdered coal are used as fuel as shown in Fig. 4.
Having thus described my invention, what I 60o claim is: 1. A boiler amplifier comprising a wall defining an open ended combustion chamber, the open end communicating with the combustion chamber of a boiler, a steam generating tube system 05 within said amplifier combustion chamber consisting of a plurality of sections of substantially rounded contour embracing fires substantially centrally positioned therein, each section of said tube system being provided with an inlet header and an outlet header with inlet and outlet pipes at ends of said sections most remote from each other, and adapted and arranged to admit and discharge fluid from said section, pipe connections between the drums of said boiler and said 76 inlet headers and pipe connections between said outlet headers and said drum, a pump between said drums and said inlet headers whereby water from said drums is forcibly circulated through said steam generating tube sections and pressure drop means between said outlet headers and said drums whereby steam and water from said tube systems are prevented from separating until the flow of steam and water has entered said drums.
2. A boiler amplifier consisting of a boiler extension comprising a pump, pipe connections from the drums of a boiler to said pump, pipe connections from said pump to a tube system of curved conformation within which the furnace fires are centered, said tube system enclosing a combustion area communicating with the combustion chamber of said boiler, said tube system comprising tubular sections, headers at top and bottom of said tube system, and risers connected from said top headers to said boiler drums through which water and steam are discharged from said tube system into said drums and pressure drop controlling means positioned at the outlets of said risers into said drums whereby separation of said water and steam is prevented until the flow has passed said pressure drop means and entered said drum.
3. A boiler amplifier comprising a tube system consisting of a plurality of sections each comprising a bottom inlet header and a top outlet header, and tubes associated with said headers of curved contour embracing fires substantially centered therein; separate pipe connections between said inlet headers and a main pipe leading from the drums of a boiler and a pump located in said main pipe; a riser pipe between each outlet header and a manifold header connecting with said boiler drums and a pressure drop device located in each riser pipe adjacent said manifold header; and valve means for cutting each section of said tube system out of operation.
4. A boiler amplifier according to claim 3 in which valve means are provided whereby each section may be closed on the inlet side and other valve means below said section for blowing down 8 said section.
5. A boiler amplifier according to claim 3 wherein the tube sections are of arcuate form having an inlet header at the foot of each side of the arch: a single outlet header at the top joining the tubes forming each side of the arch; and a coal burning grate within the ambit of said arch.
6. A boiler amplifier comprising a tube system consisting of a plurality of detachable sections each comprising a bottom inlet header and a top outlet header and tubes associated with said headers of curved contour adapted to embrace fires substantially centered therein; a main pipe leading from the drums of a boiler and connecting with each of said tube sections through separate branch pipe connections leading to the inlet headers of each tube section; a pump located in said main pipe; separate riser pipe connections leading from said outlet header of each tube sec2a tlon to a manifold header connecting with said drums and pressure drop devices located in said separate riser pipe connections adjacent said manifold header connecting with said drum; and valve means for cutting each section of said tube 80 system out of operation.
7. A boiler amplifier according to claim 6 in which each section of said tube system is composed of two semicircular groups of tubes, each group having a bottom inlet header and a top outlet header; suitable pipe connections to each inlet header from the main pipe leading from the boiler drums and suitable riser pipe connections from both said top outlet headers to said manifold header.
MICHAEL C. CROTTY.