US2243430A - Fluid heat exchange apparatus - Google Patents

Description

May 27, 1941. c. E. LUCKE FLUID HEAT EXCHANGE APPARATUS 4 Sheets-Sheet 1 Filed Jan. 11, 1938 INVENTOR.

Char/es E Lucke &8- W

y 27, 1941- c. E. LUCKE 2,243,430

FLUID HEAT EXCHANGE APPARATUS Filed Jan. 11, 1938 4 Sheets-Sheet 2 INVENT OR.

Char/e5 5L uck a M ATTORNEY.

y 27, 94 c. E. LUCKE 2,243,430

FLUID HEAT EXCHANGE APPARATUS Filed Jan. 11, 1938 4 Sheets-Sheet 3 INV ENT OR.

' cfz af/es E Lucke ATTO'RNEY.

May 27, 1941. c. E. LUCKE FLUID HEAT EXCHANGE APPARATUS Filed Jan. 11, 1938 4 Sheets-Sheet 4 INVENTOR. Char/e5 E. Luc'ke I ORNEY.

Patented May 27, 1941 2.243.430 rwm HEAT sxcmncn APPARATUS Charles E. Lucke, New York, N. Y., minor to The Babcock a Wilcox Company, Newark, N. J., a corporation of New Jersey Application January 11, 1938, Serial N0. 184,363

12 Claims.

This invention relates to fluid heat exchange apparatus, and it is particularly concerned with improvements in heaters which employ spaced tubes for conducting the fluid to be heated.

Where spaced tubes are employed for heating fluids that rise in temperature as they receive heat, and with unequal quantities of fluid in them or with unequal heating effects in different parts of the hot gas spaces occupied by the tubes corresponding inequalities in the temperature of difierent tubes have resulted and have caused those tubes to expand in different degrees. This. in many cases, has caused some of the tubes to move to positions out of their installed alignment and has presented serious problems in the maintenance of the integrity of such fluid heaters. This has been particularly true where high temperatures of the heating gases and high fluid temperatures are involved. An outstanding example of this dlfliculty is the experience which has been encountered in steam superheaters. It is one object of this invention to ameliorate such conditions and consequently improve the structure and operation of such installations.

Another object of the invention is to provide for the accumulation of ash or slag between the water tubes of a water wall of a steam boiler lying in front of a refractory backing to protect the refractory from damage that would result from its direct exposure to the furnace influences. It has been a common practice to use straight vertical water tubes in front of refractory furnace walls as a means of reducing damage to the refractory when such damage might result without such furnace face cooling. With this arrangement there are vertical strips of refractory between the water tubes that are exposed to the furnace, and there have been damages by the combined effect of high temperature and slag. By causing the ash or slag to accumulate between water tubes and in front of the refractory wall, in pockets to prevent downward movement, such refractory damage may be prevented, but heretofore no satisfactory way of meeting the conditions has been found. With the present construction providing pockets, refractory may be placed in the pockets instead of waiting for them to fill with ash or slag, and when so placed it is adequately cooled so as to resist damage.

Another object of the invention is to provide fluid heaters with multiple tubes so constructed and arranged that adjacent tubes may be welded at spaced points along their lengths so as to have a "girder effect. This feature of the invention is particularly advantageous, not only in wall tubes, but also in high temperature superheaters of the convection type employing a bank of horizontally disposed tubes extending across the path of the furnace gases. Dueto the higher steam temperatures which have been employed, the metal temperatures of such convection superheaters have become correspondingly high. Tubes are apt to be structurally weakened thereby. Various attempts have been made to overcome this problem but none of them has been completely successful.

Other objects of the invention will appear from the accompanying description when read in connection with the drawings. The latter disclose structures which illustrate different embodiments of the invention.

In the drawings:

Fig. 1 is a view in the nature of a sectional elevation indicating a modern steam generating installation burning pulverized fuel and operating at high furnace temperatures and high steam pressures.

Fig. 2 is a view in the nature of a vertical section through a boiler furnace fired by an underfeed stoker and involving walls adjacent the stoker.

Fig. 3 is a fragmentary view in the nature of an elevation of adjacent tubes associated with longitudinal flns which extend across the intertube spaces, and, when the tubes are wall tubes, operate to protect the refractory of the wall structure on the cooler sides of the tubes.

Fig. 4 is a transverse section on the line 44 of Fig. 3.

Fig. 5 is a fragmentary view in the nature of a sectional elevation indicating an embodiment of the invention in which the sinuous tubes are parallel and are provided with metallic studs to be associated with high temperature refractory material closing the spaces between the tubes.

Fig. 6 is a transverse section on the line 6-45 of Fig. 5.

Fig. 7 is a fragmentary view in the nature of an elevation of a part of a furnace wall or furnace gas boundary structure indicating an embodiment of the invention in which the adjacent sinuous tubes are so related that they provide refractory receiving pockets. These pockets are so formed that the tubes co-operate with refractory to efiectively anchor the refractory in position to resist its displacement into the furnace.

Fig. 8 is a transverse sectional view on the line 8-8 of Fig. 7.

pockets, or spaces.

Fig. is a transverse section on the line Fig. 11 is a fragmentary view of a modification of-the invention wherein the sinuous tubes, are arranged in alternation with respect to interposed straight tubes.

Fig. 12 is a transverse section on the line I2I2 of Fig. 11.

Fig. 13 is a view having some of the characteristics of a horizontal section through a steam boiler employing a convection superheater.

Fig. 14 is a view in the nature of a side elevation of the superheater shown in Fig. 13.

Fig, 15 is a view in the nature of a plan, indieating a different arrangement of the sinuous tubes in a superheater such as that indicated in Fig. 13 of the drawings. a

Fig. 16 is a-view showing an embodiment in which reversibly arranged tubes having straight sections and sinuously formed sections are associated.

In the drawings, Fig. 1 illustrates a high tem- 5 perature steam generating installation in which the illustrative sinuous tubes I0 are employed in furnace water walls. The furnace is preferably fired by pulverized fuel burners I2 located in a wall of the furnace. In the ignition zone of the furnace (and in the zone of the burners) the furnace wall tubes-are covered by refractory blocks I4. These elements are known in the art as Bailey blocks)" They are preferably supported by the tubes and clamped thereon in good heat exchange relation.

The sinuous tubes I0- exposed to the furnace gases in the furnace :wall above the blocks I4 are shown as having straight tubes I6 alternating therewith. Both sets of tubes are preferably secured at their upper ends to the header 20 from which steam and water are normally discharged into the drum 22.

Below the upper limit of the high temperature furnace zone defined by the wall blocks I4, the tubes l0 may be straight, and arranged in parallelism with the tubes I6. Both sets of tubes extend to, and are connected with, a lower header 24 which may receive an adequate supply of fluid through circulators which connect the headers 20 and 24, and other circulators affording connection with the water space of the drum 22.

The furnace walls arranged in positions normal to the plane of the wall defined by the tubes I0 and I6 may be similarly constructed. One of these walls includes the upper header 26 connected by Wall tubes 28 and outside circulators 30 with a lower header 32. An intermediate header 34 is interposed when the illustrated hopper bottom furnace is employed. The inclined tubes 30 define one inclined wall of this hopper bottom and, on the opposite side of the furnace, the inclined tubes 30 similarly define another wall of the structure. v

The hopper bottom tubes 30 are connected at their lower ends to the header 40 which is connected by outside circulators 42 to an upper header 44. The latter is connected by wall cooling tubes 46 to an intermediate header 40, in communication with the tubes 30 at their upper ends.

The wall tube header 20 is in communication with the drum 22 by means of the circulators I0 75 and 52, similar circulators I4 connecting the header 44 with the drum 22.

In the installation of Fig. 1 of the drawings the furnace gases pass upwardly across the tubes It and ll of a boiler slag screen. These tubes receive their supply of circulating fluid from the lower header 40 which is in communication with the water space of the drum .22 by means of the downtakes 02, the header construction 44, and the nipples 00.

The upper ends of the boiler slag screen tubes 50 and 00 are bent so as to have vertical portions communicating directly with the lower sides of the header construction ll. Steam and water from this construction passes through the risers I2 into the steam and water drum 22.

The header constructions 04 and I0 are connected by a bank of steam generating tubes I4 which extend across the path of the furnace gases above the slag screen. An upper row of tubes I0 over this bank are bent so as to have vertical portions separating the heating space Into two gas passes I0 and 00, above the horizontally inclined steam generating tubes. The vertical portions of these tubes are shown as connected to an intermediate header 02 from which the tubes 04 extend vertically and then horizontally to the drum 22. The vertical portions of the tubes I0 and 04 may be used to support the tubes of a convection superheater 00 as well as the tubes of'the economizer sections 02 and 04. They may also support the convection heated tubes of the fluid heater 00. Control of the division of the furnace gas flow between the two parallel passes I0 and 20 and of the total flow is effected by means of dampers I00 in the upper part of the gas pass 10 and similar dampers I02 in the upper part of the gas pass 00.

Fig. 2 of the drawings illustrates an under-feed stoker installation in which the furnace walls alongside the stoker are cooled by the illustrated sinuous tubes I04. These wall tubes are horizontally inclined as to a mean center line, connecting the lower header construction I 00 with the upper header construction I00. These header constructions may be connected into boiler circulation by the circulators III and H2 and other circulators which correspond to some extent with such circulators as those shown in the Fig. 1 installation and described with reference thereto.

The underfeed stoker of the Fig. 2 installation is provided with fuel and air feeding mechanism indicated generally at II4, the fuel bed resting upon the stoker base I I6 which has an inclination corresponding generally to the inclination of the furnace wall tubes I04. As the fuel is burned, it moves toward an ash pit Ils, the discharge of ash and clinker from this ash pit being controlled by the regulator I20.

The furnace wall at the discharge end of the stoker of the Fig. 2 embodiment is a fluid cooled wall having wall tubes I22 connected into boiler circulation in a manner similar to that of the wall tubes of the Fig. 1 installation, above described. Such connections include appropriate headers such as the bottom header I24 shown in the drawings.

The tubes cooling the wall at the discharge end of the stoker of Fig. 2 may be sinuous tubes arranged in such an association with interposed straight tubes as that shown in Fig. l of the drawings, or these tubes may be arranged in accordance with other embodiments of the invention. For example, only sinuous tubes may be employed. Their sinuosities may be parallel,

according to the embodiment of the invention illustrated in Fig. of the drawings. In that case, the spaces between the tubes will be closed by high temperature refractory material mechanically and chemically anchored in place and thermally maintained on the tubes by the metallic studs I30. These studs are preferably welded to the tubes for the purpose of maintaining good heat transfer relationship between the studs and the tubes.

The Fig. 2 embodiment of the invention may employ sinuous tubes only above the line of the Bailey blocks" I32, the tubes being upright and parallel in the zones in which the blocks are secured thereto.

Figs. 5 and 6 of the drawings show the illustrated sinuous tubes arranged in parallelism with rows of diverging studs welded to and extending from each tube into the inter-tube spaces. When such a construction is used as a part of a furnace wall, a high temperature refractory material is tamped in place over and around the studs so as to close the inter-tube spaces, the tubes being bare and directly exposed to the heat of the furnace gases along their parts between opposite diverging rows of studs. In other installations, when similar constructions are used in zones of higher temperature, the studs may be distributed entirely around the furnace sides of the tubes and the studs and those sides of the tubes entirely covered with the high temperature refractory material. For example, such a construction might be used at the discharge end of the stoker of the Fig. 2 installation, and along the lower portions of the tubes I22.

The Fig. 3 embodiment of the invention is one which may be used in furnace wall constructions in certain zones and includes the inclined wall tubes I40 and I42 with the sinuous tubes I44 interposed. At its high points, such as those indicated at I46 and I48, the latter may be welded to the parallel tubes I40 (the other similar embodiments of the invention also being contemplated as employing this welded feature when desired).

Each of the tubes I40 has multiple short metallic fins longitudinally spaced thereon and preferably welded thereto along their straight edges. These fins I50, I52, and I54 are located respectively between the high points I46 and I40 and they close to a considerable extent the spaces between the sinuous tubes and the straight tubes, leaving adequate spaces adjacent the sinuous tubes so as to prevent damage during actual operation of the apparatus in which this embodiment is employed.

When the illustrative sinuous tubes are employed in such relationship as those indicated in Fig. 7 of the drawings, they may constitute a part of the furnace wall structure which is of advantage in anchoring refractory furnace wall bodies. The tubes I60-I63, inc., may be welded at such high points as those indicated at I65 and I 68, to maintain them in their operative wallforming, relationships, and when the tubes are horizontally Linclined and arranged in superposed relationship they constitute a girder which regidifies the wall construction and may maintain it between two opposite headers without any other structural support, even if quite long in relation to tube diameter so longer spans are possible than otherwise when single tubes act as beams.

In the erection of a furnace in which the Fig. '1 structure is employed, preformed wall blocks I10 and I12 having the flanges I14 and I16 may be forced tightly into the elliptical type openings between adjacent welds I" or I 80 and sprung into position between the tubes. They will be anchored to the tubes in this manner. Even if this is not done, displacement into the furnace is prevented by the back flanges of the refractory blocks. The small separated refractory blocks are cooled on all edges and so protected against damage.

The invention also contemplates a mode of furnace wall construction in which the tubes are first erected as indicated in Fig. '1 of the drawings and the Insulation material is next placed in position along the cooler sides of the tubes. Thereafter, a high temperature refractory material constituting a part of the furnace lining may be tamped into position in pockets such as those which are above described as holding the preformed blocks I10 and I12. With this mode of construction, and in some temperature zones, the illustrative construction lends itself admirably to a combined metal and ceramic refractory wall construction in which, the ceramic refractory is effectively held in position without the use of such inter-tube studs as those which have been previously described and this refractory is well cooled by the tubes bounding its perimeter.

Such constructions as those indicated in'Figs. 9 and 10 of the drawings may be employed in such a superheater as that indicated in Figs. 13 and 14, it being understood under such circumstances, that the furnace gases are passing across tubes, and in a direction normal to the plane of Figs. 9 and 11.

In such a superheater construction as that indicated in Figs. 13 and 14, the tubes I and I82 may correspond to the water and steam risers 12 and the water downtakes 62 of the installation shown in-Flg. 1 of the drawings. If this installation is to be particularly related to the installation shown in Fig. 13, the tubes I80 and I82 would correspond to the downtakes 62 and the upright portions of the tubes 16. Steam to be superheated passes into the lower loops I84 and through the succeeding loops I86 to the superheater outlet header I88, the tubes of these loops being preferably bent in horizontal planes as indicated in Fig. 13 to avoid pockets in which water may lodge in starting. Certain high points of the bends of adjoining loops contact with each other and are welded together at such positions as those indicated at I90 and I02 in the drawings. In this way, the superheater tubes are maintained in the proper spacing and problems of differential expansion in the tubes, resulting from the different temperatures to which they are exposed, are solved. Furthermore, the drainability of the superheater is maintained to the desired degree.

With reference to the superheater construction indicated in Figs. 13 and 14 of the drawings, it should be understood that not all of the adjacent loop parts in all of the horizontal planes need to be bent as illustrated in Fig. 13 and welded together. Effective maintenance of the superheater tubes in their spaced relationship may be effected by so constructing only a fraction of the total number of loops. That is, the bending of the loops and the welding of the high points of the bends together may take place in only two or three horizontal planes, whereas the number of planes defined by the horizontally aligned looped parts may be very much larger in number. Furthermore, some of the welds at contacting bends in one plane may be omitted.

The parts of the superheater. loops arranged in any given horizontal plane maybe bent as indicated in Fig. 15 of the drawings and the high or contacting points of those bends may be welded together in the manner there shown. In this construction, it will be noted that the nodes and anti-nodes of the loops in successive horizontal planes are in staggered relationship so as to produce a heating effect which is of advantage under some gas flow conditions.

The use of the invention eliminates expensive structural provisions which have been necessary in the prior art with straight wall tubes. With the latter, it has been necessary to so structurally support and maintain one of the connected headers so that it was movable under the influence of the expansion of the straight tubes. With proper. sinuosity of tubes, both headers may be fixed in place without introduction of exsessive stresses.

It is within the scope of the invention that the sinuous tubes may be employed without contact between adjacent tubes, or without welds between' adjacent tubes. However, when the sinuous tubes do have parts in contact which are welded together, a set of these tubes acts like a girder, and, as a unit, it is stiffer than it would be without the welding. This permits the use of longer tubes of a given diameter without excessive sagging and thus eliminates the costly structural supporting metal and permits a number of the tubes to serve as a beam and carry the load of other tubes superposed with reference to the tubes. It also permits a set of these tubes, when used as a water wall, to form a direct support for the brick wall above the tubes. In such a welded assembly, such tubes may be used between the sinuous tubes, and when drainability is important, this may be maintained by inclining the whole set of tubes sufliciently with reference to the angle of the individual bends of the sinuosities.

With reference to Fig. 16 of the drawings, it will be noted that this construction can have the advantage of the girder effect" above referred to. This effect is produced when the high points of some of the bends of the curved tubes are welded to the straight sections. This construction also has the further advantage that the tubes are uniform in size and shape. It presents a combination of straight and curved tubes in which each tube has a straight section and an undulating section, these sections being reversed as to adjoining tubes when a plurality of the tubes are connected into opposite relationships. This construction may be used so that the straight tubes run horizontally in some instances. In others, they may be inclined or upright as in water wall constructions.

While, in compliance with the Federal Statutes, and particularly see. 4888 R. S., I have described my invention with reference to certain particular structures, the invention is not limited to all of the details thereof. It is rather of such a scope-that it may be exemplified in various combinations of the details taken from the different embodiments which are illustrated in the drawings. For example, the structure which is indicated in Fig. 3 of the drawings might be employed with a stud tube and refractory construction such as that described with reference to Fig. of the drawings. Again, either one of the constructions indicated in-Figs. 3 and 5, or different combinations of details, some taken from one of these structures, and others taken from the other, might be used in such a side wall construction as that indicated in Fig. 2 of the drawinss. Also, such a water wall construction as that indicated in Fig. 1 of the drawings might be. modified in accordance with the details of the structures indicated in Figs. 3, 5, 9, 11, 7, or 16. Further, such refractory closures as those indicated in Fig. '7 of the drawings might be used in conjunction with the embodiment of the invention which is indicated in Fig. 11, or that shown in Fig. 16. Still further, such convection superheaters as those indicated in Figs. 3, 14, and 15 of thedrawings might include some of the details of the embodiments indicated in Figs. 1, 3, 11, and 16.

I claim:

1. In a fluid heater, a furnace wall, sinuous wall tubes spaced from each other and arranged with their sinuosities so disposed that opposite surfaces of the tubes throughout their eflective lengths are tangent to parallel planes having a spacing of the diameter of the tubes, means connecting the tubes together in a wall assembly, means for connecting the assembly into a fluid circulation, and means whereby said tubes are subjected to the heat of furnace gases.

2. A fluid heater including spaced sinuous furnace wall tubes subjected to the effect of a heating fluid, and means for connecting said tubes together with their sinuosities and axes in the same plane, adjoining tubes being rigidly joined at the positions of adjacent and opposing high points of the sinuosities.

3. In a fluid heater, a furnace, a plurality of sinuous wall tubes superposed with reference to each other and supported at their ends, means for connecting said tubes into a fluid circulation, the tubes being so arranged that the high points of opposing sinuosities of adjacent tubes are in contact, and means rigidly joining said tubes at the contact positions only so that the group of tubes acts as a girder, thus allowing long tubes to be used without necessitating costly supporting structures intermediate the tube lengths.

4. In fluid heat exchange apparatus, a furnace having a refractory wall, and sinuous wall tubes 50 arranged along the wall of the furnace that their corresponding sinuosities are in alignment and oppositely directed, pockets being thus formed by said corresponding sinuosities and said wall for the anchorage of refractory wall protecting material.

5. In Iluid heat exchange apparatus, a furnace, a plurality of spaced and parallel straight tubes arranged in alignment along a wall of the furnace, sinuous tubes arranged alternately with reference to the straight tubes and having the high points of their sinuosities substantially in contact with the straight tubes, and means rigidly securing the sinuous tubes to the straight tubes at the positions of contact in order that the entire tube wall shall be rigidified.

6. In fluid heat exchange apparatus, a furnace, sinuous tubes arranged along a wall of the furnace with the corresponding sinuosities of adjacent tubes extending oppositely, metallic studs welded to the tubes and extending into the pockets formed by the oppositely extending sinuosities, and high temperature refractory bodies installed in a semi-plastic condition in said pockets.

7. A fluid heat exchange unit consisting of similar and reversibly arranged tubes, each tube having a straight portion for a substantial portion of its length and the remaining portion of the tube formed to present a plurality of sinuosities, the sinuosities of one tube being arranged adjacent the straight portion of an adjoining tube.

8. In a steam generator, a furnace, a stoker, inclined sinuous wall tubes arranged in wall forming alignment so as to define the furnace walls on either side of the stoker, means rigidly connecting adjacent tubes intermediate their ends so that they may be effective as a construction somewhat in the nature of a girder, and means for connecting said tube into the fluid system of the generator.

9. In a. steam boiler, a furnace, a stoker for firing the furnace, sinuous wall cooling tubes acting as parts of .the furnace walls at the sides of the stoker, means connecting said tubes into the fluid system of the boiler and supporting the tubes at such an inclination that they will drain by gravity.

10. In a fluid heater, a furnace, means for burning a slag forming fuel in the furnace, sinuous wall cooling tubes arranged with the planes of their sinuosities in the plane of a furnace wall and with the corresponding sinuous portions of adjacent tubes arranged in opposition to thereby form pockets for the accumulation of slag, and means connecting said tubes into the fluid system of the heater.

11. In a fluid heater, a furnace, sinuous tubes arranged along a wall of the furnace with parts thereof exposed as bare metal to the heat of the furnace and their sinuosities so disposed as to present pockets receiving refractory material, and refractory material disposed in pockets between the sinuous tubes and arranged .to present separated furnace face areas interspersed with reference to the bare metal exposed by the tubes.

12. In a fluid heat exchange unit comprising, in combination, a plurality of spaced and sinuous cylindrical tubes with .the axes of the tubes and their sinuosities arranged substantially in single plane formation, an inlet header at one end of the unit and rigidly connected to the corresponding ends of all of the tubes, and an outlet header at the other end of the unit and rigidly connected to the remaining end of all of the tubes, the tubes being connected together at their sinuosities at distributed points throughout the length of the tubes, such connections co-acting with the tubes and headers to form a self-sustaining unit.

CHARLES E. LUCKE.

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