US2141917A - Boiler - Google Patents

Description

Dec. 27, 1938.; H. E. KLEFFl-:L

BOILER s sheets-sheetL 1 Filed May 5, 1936 ATTORNEYS Dec. 27, 1938. H. E. KLEFFEL 2,141,917

BOILER Filed May 5, 1936 3 Sheets-Sheet 2 Dec. 27, 1938. H. E.-KL.EFFEL 2,141,917

BOILER a Filed May 5, 195e s sheets-sheet 3 Q I Egli:

ATTORNEYS Patented Dec. 27, 1938 UNITED STATES PATENT OFFICE 4 Claims.

This invention relates to steam boilers and furnaces therefor and is concerned more particularly with improved boilers of the horizontal return tubular and similar types containing various novel features of construction, the use of which improves the combustion efficiency in the burning of the fuel in the furnace and adds to the steam production capacity of the boiler. The boilers of the invention are based on the principles disclosed in my Patents Nos. 1,884,741 and 1,884,742,1and may, therefore, be considered to constitute improvements on the patented apparatus. The new boilers depart from the disclosures of the patents in various respects, however, and these features will be pointed out hereafter in detail.

As explained in the patents referred to, efficient combustion in a boiler furnace requires that the gases be consumed to as great an extent as possible before they reach the bare heat absorption surface in the boiler. `As a result, it was the common practice prior to my patented inventions to construct large furnace chambers through which the burning gases would flow unobstructed in a streamline manner without appreciable mixing and turbulence, thus requiring a long path of travel so that the fuel could be substantially completely burned before leaving the chamber. Such large combustion chambers were frequently lined with water Walls, and because of that and of their size, their cost of installation was high. The inventions of the patents are directed to the provision of furnace chambers in which substantially complete combustion can be attained without the chambers being of such large dimensions as were previously considered necessary, and in the patented apparatus, the desired combustion efficiency is achieved by providing means in the region in the chamber in which combustion is taking place for creating turbulence in the gas stream and thereby promoting diffusion of the gases with the air.

In the patented apparatus, the desired turbulence and mixing of the gases and air is obtained by the use of a bank of water tubes in the furnace chambers in the path of the owing gases in a zone of relatively high temperature, the tubes in the bank being so arranged as to provide a plurality of passages through which the gases flow on their way out of the chamber. Such water tubes, if wholly bare, however, will extract so much heat from the burning gases as to reduce the temperature of the gases which come in contact with the tubes below the combustion temperature and will, therefore, hinder rather than promote combustion. Accordingly, the tubes are covered, wholly or in part, by a covering which permits the contents of the tubes to absorb heat only at a limited or controlled rate, so that the gases are not cooled to a detrimental extent. 5 Since the tubes are connected in the water circulation of the boiler, they add to its steam production capacity and at the same time the Water in the tubes serves to protect the covering, so that the covering has a long life.

The present invention involves the application of the principles of the patented inventions to boilers of the horizontal return tubular and similar types, and in such a boiler, Water tubes connected in the water circulation of the boiler are installed in the furnace chamber in a bank or plurality of rows lying a substantial distance below the boiler shell. These tubes extend through the furnace chamber from end to end and they lie inclined to the horizontal and generally transverse to the direction of flow of the gas stream. In that portion of the furnace chamber in which combustion is taking place, the tubes are covered by a covering which controls the rate of heat absorption, and elsewhere, particularly in the region where the combustibles in the gases have been substantially fully consumed, the tubes are bare. If desired, the bank of tubes mayv be made up of a plurality of units each consisting of a pair of horizontal headers and a row of tubes connecting the headers, with the tubes in adjacent headers either aligned in vertical rows or staggered, In a modified construction, the tubes of the bank are connected to vertical headers and in that part of the furnace chamber where combustion is initiated, the tubes lie along the sides of the chamber and are covered, while in the remainder of the chamber, the tubes lie somewhat more directly in the path of the burning gases and are in part covered and in part bare, the covering lying in the region where combustion is continuing. With either construction, the tubes in the furnace chamber tend to prevent stratification in the gas stream and create turbulent conditions which accelerate the rate of combustion. At the same time, the tubes add substantially to the steam production capacity of the boiler.

As another feature, the invention includes a novel covered tube which may be used in the bank of tubes in the furnace chamber for the purposes above described. This new tube includes a refractory or heat insulating covering and a simple and effective means by which the covering may be maintained in place on the outside of the tube.

For a better understanding of the invention, reference may be had to the accompanying drawings in which Figure 1 is a longitudinal section of a horizontal return tubular boiler with a bank of tubes of the invention disposed in the furnace chamber below the boiler shell;

Figure 2 is a view of the boiler shown in Figure 1, partly in front elevation and partly in section on the line 2 2 of Figure 1;

Figure 3 is a sectional view on the line 3--3 of Figure 1;

Figure 4 is a developed view of a sleeve employed in retaining the covering on the tubes of the bank;

Figure 5 is a cross-sectional view of a covered tube with a sleeve in place;

Figure 6 is a view similar to Figure 4 showing a modified construction;

Figure '7 is a-longitudinal section of a modified form of the tube bank of the invention; and

Figures 8 and 9 are sectional views on the lines 8 8 and 9-9, respectively, of Figure 7.

Referring now to the drawings, the boiler illustrated in Figure 1 includes a shell I0 containing fire tubes II and supplied with feed water through a pipe I2 and having a steam discharge pipe I3 and a blow-off discharge pipe I4 of the usual construction. The shell is mounted on a setting consisting of front and rear walls I5, IB and side walls I'I, these walls defining a furnace chamber I8 and a passage I9 through which the gases pass from the chamber to the re tubes I I.

Fuel in any desired form, solid, liquid, or gaseous, may be supplied to the furnace chamber for combustion therein, and in the construction illustrated, the furnace is of the hand fired type and includes a grate 28, carrying a bed of fuel 2| which is replenished through the door 22. Within the furnace chamber to the rear of the grate is the usual bridge wall 23 provided with a stub baille 24 at its top, and rearward of the bridge wall is the baffle 25, the baffles being so arranged that the gases flow in a generally upward direction from the fuel bed over the top of the bridge wall and stub baiile, then downward beneath the lower end of the baffle 25, and then upward in the passage I9 to the fire tubes. After flowing through the re tubes, the gases pass through the exit flue 26 and are discharged. Particles of ash carried along by the gases are collected in the fiy ash pocket 21 beyond the bridge wall and may be removed through the rear door 28.

Within the furnace chamber below the boiler shell is a bank of tubes generally designated 29, these tubes extending lengthwise of the furnace chamber and througha portion of the passage I9, and lying substantially transverse to the direction of flow of the gases in their successive passes in the furnace chamber and passage. The tubes are connected at their ends to horizontal headers 30 and 3l, the headers 30 being supplied with water from the boiler shell through downcomers 32 connected to the headers by nozzles 33. The uptake headers 3| discharge steam and water through nozzles 34 into riser pipes 35 which eX- tend upwardly along the sides of the boiler shell and discharge into it at points 36 which lie at or above the water line. The tubes in the bank 29 are thus connected to the boiler shell in such a manner that a positive circulation through the tube bank is provided countercurrent to the flow of burning gases, and improved water circulation within the boiler shell is obtained.

As shown in Figures 2 and 3, the units of the bank, each consisting of a pair of headers 30, 3| and tubes 3'I between the headers, may be of kinds which differ with respect to the arrangement of the tubes relative to the headers and by the proper selection of units in constructing the bank, gas passages through the bank of different forms may be provided. With any arrangement, the wide spacing and location of the tubes in the path of the traveling gases causes the tubes to create turbulence in the gas stream so that the burning gases are thoroughly mixed with the air necessary to insure 'complete combustion.

In that part of the furnace chamber directly above the grate, that is, in the region where combustion is initiated, the tubes, if bare would absorb so much heat from the gases contacting with them as to lower the temperature of those gases below that of combustion, and would thus hinder rather than promote combustion. Accordingly, in this portion of the furnace chamber, as well as in the first pass between the baiiies 24 and 25, where combustion is continuing, the tubes are provided with coverings which limit and control the amount of heat absorbed by the contents of the tubes. Beyond the baille 25, the gases are substantially completely consumed and the portions of the tubes in the last pass of the gases upward through the passage I9 are bare so that these parts of the tubes may act as more effective heat absorbing surface.

In the construction shown in Figures 7 to 9, inclusive, the boiler shell 38 with re tubes 39, feed water pipe 4G, steam discharge pipe 4I, and blow-off discharge 42 is of the construction previously described. The boiler setting again includes front and rear walls 43, 44, and side walls 45, 46 defining a furnace chamber 41 with a passage 48 leading from the chamber to the fire tubes, and within the furnace chamber is a bridge wall 49 and a baille 50. The furnace chamber illustrated is of the mechanically fired type with the fuel supplied by means of a burner 5I which may be supplied with powdered fuel, oil, gas, or a combination of such fuels.

Outside the rear wall 44 of the setting is a vertical header 52 from which lead tubes 53 arranged in a bank and Within the passage 48 and in the pass in the furnace chamber between the bridge wall 49 and baille 50, the tubes lie spaced across the furnace chamber and passage. At the forward end of the pass, the tubes are bent outwardly, and forward of the bridge wall 49, the tubes lie along the side walls of the combustion chamber. Beyond the front Wall 43, the two groups of tubes are connected to vertical headers 54 from which lead risers 55 which discharge into the boiler shell at or above the water line at the points 56. Water from the shell is supplied to the rear header 52 through downcomers 5l.

With the construction shown in Figure 7, those portions of the tubes 53 which lie within the furnace chamber ahead of the bridge wall and in the pass between the bridge wall and the baffle 570 are provided with a covering so that the tubes may create the desired turbulence in the gaseous stream, without abstracting so much heat from the gases as to interfere with their combustion. Beyond the baffle 58, the tubes 53 are bare so that they may absorb the maximum, abount of heat from the gases, the combustion of which has been completed.

Various types of coverings for the tubes may be provided and in Figures 4 to 6, inclusive, I have shown two different forms of such tubes. In the construction shown in Figure 5, the tube proper 58 is inclosed within a metal shell made up of arcuate metallic sleeves 59 provided with edge flanges 6D which are secured together by welding. The tubes shown in Figure 5 are provided with two sleeve sections which are of semicylindrical shape, but more such sections may be used if desired. Each section is formed of a fiat sheet of metal which is then bent to fit the outside of the tube and it is provided with a plurality of projections Eil formed by punching and piercing the sheet at spaced points and forcing the metal out of the plane of the sheet so as to form the rough projections indicated. After formation of the projections, they are preferably bent over or rosetted. The necessary number of such sections are then applied so as to t the tube tightly, and the sections are secured in place by having their flanges welded together. The heat insulating or refractory material 62 is next applied in plastic form on the outside of the sleeve, this material being held in place by the projections which interlock with the covering and hold it securely in place after the covering has set. In the construction shown in Figure 6, the sheet of metal 63 which is to form a sleeve section is pierced so as to provide tongues 54 of generally triangular shape. These tongues are then bent over and provide a means for holding and interlocking the refractory covering in place on the tube.

Sleeves ofcthe construction described not only serve as a simple and effective means for securing the refractory covering on the tubes, but they also strengthen the tubes against bursting and bending. The sleeves are of relatively light weight and low cost, and can be easily fitted to the tubes either in the shop or in the field. While the sleeve sections may be best secured together by welding, other methods such as riveting or clamping may be employed for the purpose. Similarly, the projections formed from the sleeves may be made in other ways and with otherA shapes than those above referred to. The character of the covering employed on a particular tube depends on the use of the tube, and the kind of covering material and the thickness of the covering may be varied according to particular conditions of use.

In all adaptations of the invention, the tubes are so distributed in the furnace chamber as to produce the desired eect of accelerating combustion, and the extent to which the tubes are covered will be varied so that the desired combustion conditions are obtained. The bare portions of the tubes provide heat absorptive surface of a highly effective type and by properly proportioning the covered and bare surfaces of the tubes, increased combustion efficiency and increased steam production capacity are obtained.

I claim:

l. In a boiler installation,.the combination of a furnace chamber having a zone in which combustion of fuel takes place, means for introducing fuel into the furnace chamber for ignition and combustion therein, a fire tube boiler, the inlet to the tubes of which is beyond the furnace chamber in the direction of flow of the gases of combustion, a zone between the inlet to the fire tubes of said boiler and the zone in which combustion of the fuel takes place through which the gases of combustion flow after combustion of fuel is substantially completed, a bank of Water tubes extending through said zones and connected with said boiler to provide a circulatory system, at least a portion of those tubes of said bank which pass through the zone in which combustion of the fuel takes place being covered with refractory material, and at least a portion of the tubes which pass through the zone in which combustion of the fuel is substantially completed being bare, the tubes of said bank being spaced from'one another to provide passage for the fuel being consumed and the gases of combustion, the tubes of said bank extending generally transverse to the direction of ow of the gases, whereby the passage of gases between and about said tubes causes diffusion and turbulence thereof.

2. In a boiler installation, the combination of a furnace chamber having a zone in which combustion of fuel takes place, meansfor introducing fuel into the furnace chamber for ignition and combustion therein, a fir-e tube boiler, the inlet to the tubes of which is beyond the furnace chamber in the direction of flow of the gases of combustion, a Zone between the inlet to the re tubes of said boiler and the zone in which combustion of the fuel takes place through which the gases of combustion flow after combustion of fuel is substantially completed, a bank of water tubes extending through said zones and connected with said boiler to provide a circulatory system, bale means for causing the fuel being consumed and the gases of combustion passing between and about said tubes to take a tortuous course, at least a portion of those tubes of said bank which pass through the zone in which combustion of the fuel takes place being cover-ed with refractory material, and at least a portion of the tubes which pass through the zone in which combustion of the fuel is substantially completed being bare, the tubes of said bank being spaced from one another to provide passage for the fuel being consumed and the gases of combustion, the tubes of said bank extending generally transverse to the direction of flow of the gases, whereby the passage of gases between and about said tubes causes diffusion and turbulence thereof.

3. In a boiler installation, the combination of a furnace chamber having a zone in which combustion of fuel takes place, means for introducing fuel into the furnace chamber for ignition and combustion therein, a re tube boiler, the inlet to the tubes of which is beyond the furnace chamber in the direction of flow of the gases of combustion and in part located over the furnace chamber, a zone between the inlet to the fire tubes of said boiler and the zone in which combustion of the fuel takes place through which the gases of combustion flow after combustion of the fuel is substantially completed, water tubes extending through said zones and connected with said boiler to provide a circulatory system, a bridge wall in said combustion chamber, a baille beyond the bridge Wallin the direction of flow of the gases of combustion, said water tubes lying in two groups extending along the sid-e walls of the combustion chamber forwardly of the bridge Wall and forming a bank in the combustion chamber to the rear of the bridge wall, at least a portion of the water tubes which pass through the zone in which combustion of the fuel takes place being covered with refractory material, and at least a portion of the tubes which pass through the zone in which combustion of the fuel is substantially completed being bare, vsaid water tubes being spaced from one another to provide passages for the fuel being consumed and the gases of combustion, said tubes extending generally transverse to the direction of flow of the gases, whereby the passage of gases between and about said tubes causes diffusion and turbulence there- 4. In a boiler installation, the combination of a furnace having a zone in which combustion of fuel takes place, means for introducing fuel into the furnace chamber for ignition and combustion therein, a re tube boiler, the inlet to the tubes of which is beyond the furnace chamber in the direction of flow of gases of combustion, a zone between the inlet to the re tubes of said boiler and the zone in Which combustion of the fuel takes place through which the gases of combustion flow after combustion of the fuel is substantially completed, a bank of water tubes extending through said Zones, at least a portion 'of those tubes of said bank which pass through the zone in which combustion of the fuel takes place being covered with refractory material, and at least a portion of the tubes which pass through the zone in which combustion of the fuel is substantially completed being bare, said bank of tubes being connected to said boiler to provide a circulatory system such that the water ows through said tubes from the bare portions to the covered portions and in a direction countei'current to the direction of oW of the gases, the tubes of said bank being spaced from one another to provide passages for the fuel being consumed and the gases of combustion, the tubes of said bank extending generally transverse to the direction of flow of the gases, whereby the passage of gases between and about said tubes causes diffusion and turbulence thereof.

HARRISON E. KLEFFEL.

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