US2204154A - Fluid heat exchange device - Google Patents

Description

June 11, 1940. f U, SAVQYE 2,204,154

FLUID HEAT EXCHANGE DEVICE Filed Oct. 27, 1933 f 4 Sheets-Sheet l V n l` n In ,1 In u Y if HMM 'um l! Il H fj/ 6 Il ii n H 6 l/A/ ff f/ ./,f V/4/ l V/I/ lOl lol

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Figi I INVENTOR Char/es U 5a voy@ BERG?. m

ATTORNEY June 1l 1940- c. u. sAvoYE FLUID HEAT EXCHANGE DEVIVCE Filed Oct, 27, 1933 4 Sheets-Sheet 2 INVENTOR I @fiar/es U Sal/0 e AT ORNEY June 11, 1940. C. U SAVOYE Y 2,204,154

FLUID HEAT EXCHANGE DEVICE Filed Oct. 27. 1933 4 Sheets-Sheet I5 l INVENTOR Char/es USm/oye ERK-T TTORNEY June 11, 1940. Q LJ- SAVOYE i I 2,204,154

FLUID HEAT EXCHANGE DEVICE Filed Oct. 27, 1935 4 Sheets-Sheet 4 Fig@ i8 Fi gf 37 INVENTOR /4 Char/es U Savoye mgm` A TORNEY Patented June 11, 1940 UNITED STATES PATENT OFFICE FLUID HEAT EXCHANGE DEVICE Application October 27, 1933, Serial No. 695,450

4 Claims.

This invention relates to fluid heat exchange apparatus and it is exemplified by superheater improvements whereby a-n even superheat is attainable in spite of varying loads on the boiler with which the superheater is associated.

It has been recognized that convection superheaters result in varying superheat temperatures when they are operated in conjunction with a steam boiler which is subjected to varying loads.

Various schemes have been proposed to overcome this defect but none has resulted in an apparatus which has been generally adopted. It is an object of this invention to provide a commercially successful device which achieves the desired result by varying the effectiveness of superheater tubes as the boiler load varies. The invention aims to accomplish this result by so varying the arrangement of the superheater tubes that gases sweeping over those tubes have their effectiveness varied as boiler loads vary.

More specifically, the invention includes within its purview mechanical means for bending superheater tube coils from their uniform spacing at normal boiler loads to change their heat exchange effectiveness, and thereby keep the superheat constant as the boiler load varies.

l It is also an object of the invention to effect, in a superheater boiler, a constant superheat by cci-relating changes in superheater tube effecso tiveness and changes in boiler rating.

Other objects of the invention will appear as the accompanying description proceeds.

The invention will be described with reference to the accompanying drawings, in which:

Fig. l is a horizontal section through a boiler setting showing the illustrative superheater in plan.

Fig. 2 is a view in the nature of a transverse vertical section of the Fig. l structure indicating a uniform spacing of the superheater coils.

40 Fig. 3 is a section similar to that shown in Fig. 2 but indicating the spacing of the superheater coils after the controller has been operated to move alternate coils.

Fig. 4 is a View in the nature of a side elevation showing an embodiment of the invention involving a convection superheater of the interdeck type.

Fig. 5 is an upright sectional view taken on the line 5-5 of Fig. 4 and showing many of the parts 50 in elevation.

Fig. 6 is a detail section taken transversely of the superheater tubes and indicating the arrangement of the parts when the dampers or baffles are moved to shield some of the tubes in 55 one group.

Fig. 7 is a detail view illustrating the manner in which the movable ends of some of the superheater tubes are secured to a transverse actuator tube which acts as a part of a superheat controller. 5

Fig, 8 is a detail view showing the parts illustrated in Fig. '7 and taken from the position indicated by the line 8 0.

Fig. 9 is a transverse section of the boiler installation ta-ken on the line 9--9 of Fig. 4 and )o showing the superheater parts in plan.

Fig. 10 is a vertical section similar to Fig. 5, but showing an embodiment of the invention inv Volving a plurality of plates forming the bailles.

Fig. l1 is a detail view indicating the manner 15 in which the fixed superheater tubes are held in position.

Fig. 12 is a detail sectional view taken on the line I2-l2 of Fig. 11.

The superheater indicated in Figs. 1 and 2 2O consists of iiat coils of return bend tubes extending across a gas pass and connected to a header 2 which may support them at one end of the boiler setting. At the other end of the setting some of the superheater tubes are supported by controller tubes 3 through brackets 4. These controller tubes are mounted in gas sealing stufllng boxes 5 so as to have sliding movement across the gas pass and through the boiler setting. They may constitute a part of a single loop as indicated in Figs. 1 and 2 and there may be separate motors 6 for moving each of the upper and lower tubes 3.

When the illustrative superheater is associated with a bank of boiler tubes, the arrangement of the superheater coils indicated in Fig. 2 may be considered the normal arrangement. In this embodiment alternate superheater coils are connected to the` tubes 3 and the remaining coils 1 may be fixed to any other suitable support. When the boiler rating is increased and it is desired that the superheat remain the same as it is under normal conditions, the motors 6 are operated to move the controller tubes 3 so that alternate superheater coils are moved into positions adjacent to or in contact with the intervening fixed coils. When this is done, there are present groups 8 of superheater coils with the gas passages betwen them greater than the gas passages indicated in Fig. 2. This action so changes the effectiveness of the superheater coils that the superheat does not vary with the boiler rating.

In order that the tubes 3 of the superheat controller may be protected against overheating they are fluid cooled by reason of their connection by the tube sections 9 with the header 2. Steam thus circulates through the tubes of 'the superheat controller. It is to be understood that there are two tube sections or tube lengths il, one above the other, and that one may be connected to the inlet header 2 while another is connected to a similar outlet header (not shown).

The superheat controller, as indicated in Fig. l of the drawings may include a temperature responsive bulb lill] positioned in the superheater header 2, or otherwise where it is sensitive to superheat steam temperature. This bulb is connected by a hollow capillary water tube |06 to a Bourdon tube |02, the free end of which tends to move counter-clockwise for an increase in temperature and clockwise for a decrease in temperature. The temperature measuring system including these elements is filled with a gas, such as nitrogen, so that changes in temperature at the bulb cause expansion or contraction of the gas with corresponding movements of the Bourdon tube.

A pointer |03 is carried by the movable end of the Bourdon tube and is positioned adjacent a scale |04 for visually indicating the instantaneous value of temperature. The arm |03 also carries a contact connected to a power supply line H0, and this arm is moved relative to two spaced contacts |05 and |66 which are respectively connected to lines |09 and i0? leading to the motors 6.

When the superheat increases above an optimum, the arm |03 moves counter-clockwise, closing the circuit including the contact |95 and the line ||9, and thereby energizing the left-hand motor 5 for rotation in the proper direction to put the controller tube 3 under tension and move it in a direction to cause a lowering of the steam temperature. Conversely, if the steam temperature should fall below a predetermined point, then there will be a closing of the circuit including the arm m3, the contact It@ and the lines H6, |07 and |08 to rotate the righthand motor in such a direction as to move the controller tubes 3 in the opposite direction. It will be noted that the wires leading to the two motors are oppositely connected so that the motors will run in opposite direction.

The convection superheater shown in Fig. 4 is located between banks of boiler tubes. As shown, the tubes i0 of the lower bank of steam generating tubes connect downtake headers I2 to uptake headers lil. Above this bank of tubes and materially spaced therefrom is a second bank of tubes I6 connecting downtake headers i8 to uptake headers 2S. Preferably, the uptake headers of the different tube banks are connected by nipples 22. Corresponding nipples 24 connect the downtake headers.

Fig. 4 of the drawings illustrates a section of a water tube boiler installation, certain parts of the boiler being omitted to avoid unnecessary disclosures in the drawings. For instance, it

. will be understood by those skilled in the art that the headers i8 are connected to the water space of a steam and water drum, and that horizontal circulators connect the headers 20 to that drum. It will also be understood that hot gases move upwardly across the boiler tubes and superheater tubes. These gases are confined generally to the space between the headers at opposite sides of the boiler setting, but a boiler casing indicated generally at i9 and 2| prevents the esl cape of such gases from the setting.

The superheater consists of at coils 26 each made up of bent tubes. As shown, each coil is connected to the inlet and outlet headers 28 and 3i) by inlet and outlet sections 32 and 34. These preferably extend between successive downtake nipples 2d as indicatedin Fig. 4 of the drawings.

In order that hot gases proceeding over the boiler surfaces shall not short circuit the superheater, closure structures are provided at the ends of the bank of superheater tubes. At the end of the superheater adjacent the downtake headers there is shown a wall structure preferably extending along the downtake nipples 24. Near the top of this structure and preferably located in Contact with the superheater connections 34 is the baffle i3. At the other end of the superheater a closure member l5 contacts with the superheater tubes and with the uptake headers M. This member is preferably held in posit tion by spacers Vs' secured to the upper superheater tubes, these spacers permitting relative sliding movements of the superheater tubes and the member.

Successive tube lengths of each superheater coil are preferably connected by struts arranged throughout the coil in a truss formation. As shown, the struts 25, 2? and 29 near the midportion of each coil are arranged in two rows downwardly diverging toward the lower ends of the oblique rows in which the end struts 3| and 3.3 are aligned. This double truss formation advantageously stiflens the superheater coil. The individual struts may be formed into two relatively movable interlocking parts permitting adjacent tubes to have relative longitudinal movement.

At the side of the vgas pass formed by the uptake header M, the superheater tubes are supported by brackets 36 preferably welded to the inner sides of the uptake headers. Each superheater coil has its upper bent tube provided with an extension i3 which hooks over the upstanding part of the bracket 36 as indicated in Fig. 4 of the drawings. This construction will permit some of the superheater coils to be separately shifted along the brackets 36. During such action the extensions 38 slide along the brackets 36. Others of the superheater coils of the separate groups may be held in fixed position transversely of the setting by the location of their extensions between stops 37 formed on the bracket 36. This arrangement of elements is clearly shown in Figs. l1 and 12.

Insofar as Figs. ll. and l2 show merely a manner in which a fixed superheater tube is held in position by the lugs 31 on the bracket 36 which slidably supports the extension 38 of a movable tube, the structure of these gures is applicable to the types of structures shown in Figs. l, 4 and 10. In addition, Fig. l2 illustrates an embodiment in which three superheater tubes are in a group, the central tube of each group being held fixed against movement transversely of the tubes while the adjacent tubes are sliclably supported for movement toward or away from the xed tube.

The coils of the superheater have their movable ends formed with studs 4|] which are connected by members 42 with a tubular actuator 44 acting as a. part of a superheat controller and preferably connected into the iiuid circulation of the system so that it will be maintained at a satisfactory temperature regardless of variations in temperature of the hot gases. In Fig. 5 there is shown an upper actuator 44 and a lower acfic lisv

tuator 46 slidably mounted in the walls 48 and 58 of the boiler setting. They extend through openings 52 formed in the walls and may be supported by structures 54 which are in the nature of stuffing boxes, These structures prevent the escape of heating gases from the boiler setting, as well as provide slidable supports for the tubes' 44 and 46. The actuator is connected by tubular parts and 41 to the headers 28 and 3|).`

As clearly indicated in Fig. 5 of the drawings, the upper and lower actuators are formed as a single loop tube having a bight 43 connecting the upper and lower parts. This tube has an upper part 45 integrally extending from the actuator 44 and connected to the header 30. A similar part 41 constitutes an extension of the actuator 46 and is connected to a superheater header 28. This is clearly shown in Fig. 4 of the drawings.

Externally of the wall 48 the actuator tubes 44 `and 46 have secured there-to racks 55 and 56. These racks are engaged by pinions 58 and 60 which may be driven by thermally controlled motors to pull the tubes 44 and 46 through the wall 48 and thus vary the positions of the connected superheater tubes. 'I'he motors 51 operating the pinions 58 and 60 may be controlled thermally and automatically to move some of the superheater tubes in response to changes in superheat temperature.

Exteriorly of the wall 5D the upper and lower tubes or actuators 44 and 46 are provided with racks 62 and 64 engaged respectively by pinions 66 and 68 which may be coordinated in their operation with the pinions 58 and 60. These pinionsare operable to. put the tubes 44 and 46 under tension to move them in a direction opposite to the movement which they have in response to the turning of the pinions 58 and 60.

It is an important feature of the present invention that the tubes 44 and 46 of the superheat controller are not placed under compression when the controlling mechanism is being operated to modify the flo-w of heating gases across the bank of superheater tubes and to shield some of these tubes from the gases. The-y are always put under tension.

The parts 45 and 41 are flexed when the motors 51 are operated to move the actuators and shift the movable superheater tubes and their movable bailes. The extent to which the parts 45 and 41 move is indicated by the full line and dotted line positions shown at the right of Fig. 9. This figure also clearly indicates the manner in which the parts 44, 45, 46 and 41 are formed as a single loop extending from one of the superheater headers to the other. There is thus provided a fluid cooled superheat control mechanism.

A temperature responsive device in contact with the superheated steam may, by suitable switches, control the operation of the motors to maintain a constant superheat. Thus, in conjunction with the superheater tube shielding devices to be described later, a better draft resistance is maintained over a Wide range of ratings, and the best available use of draft is made at low ratings.

Fig. 9 of the drawings indicates a boiler and superheater installation in which there are three movable superheater coils 10, 12 and 14. They are attached to the lower and upper actuators 46 and 44 in the manner indicated in Figs. 7 and 8 of the drawings.

Considering the relation of the baffles 18 and 80 tov the superheater tubes as indicated in Fig. 6, the bafes are carried by the movable superheater coil 16. They act as superheater tube shields, and preferably consist of similarly `formed plates or tile with thickened end portions 82 grooved so as to interlock with the upper and lower pairs of tube lengths in the coil 16. As shown in Fig. 6 there is a free and unoccupied space between two groups of superheater tubes 84 and 86. Under these conditions, the heating gases may flow freely between the groups of tubes, extended portions of the ballles being positioned between upper and lower rows of tubes in the superheater coils of the group 86. This arrangement of elements may be considered to illustrate one condition of the apparatus when the boiler is operating at a high rating. When, as at low ratings, it is desired that the spaces or passages between the separate groups of superheater tubes be closed so that all of the heating gases will pass over the coils of superheater tubes, the superheat controller including the tubes 44 and 46 is moved so as to carry the baffles 18 and 86 to the positions illustrated in dotted lines in Fig. 6.

At high ratings, the illustrative superheater control mechanism not only modifies the flow of gases over the superheater, but also moves the various series of dampers or bailies to shield an increasing number of thel superheater tubes.

vThe fact that the positions of such shielding are distributed across the superheater promotes good distribution of gas contact across the boiler heat absorbing surfaces in all stages of adjustment of the control mechanism.

' Fig. 9 of the drawings illustrates the superheater construction with all of the passages or spaces between the groups of superheater tubes being closed off by the dampers or baffles. These baffles may be formed of tile or small sections as indicated by the junction lines 88. Desirable modification of the described apparatus may be effected by the omission of some of the sections constituting the dampers or baiiies.

Fig. 10 discloses an embodiment of the invention wherein plates, ypreferably of metal, are used as the baffles or shields secured to the movable superheater coils. In this figure, the movable superheater coil is indicated at 13. This coil carries three metallic plates 94, 96 and 98 preferably resting upon and welded to certain of the tubes of the coil. Excessive local eddying or circulation of the hot gases between the upper and lower parts of the superheater coils is prevented by the intermediate plate 96.

It will be noted in connection with the disclosure of Fig. 9 that the spacing ofthe superheater tubes along the header 28 is uniform. At the other end of the superheater the separate coils of superheater tubes have been flexed or moved so that they are located in such spaced groups as those which have been heretofore described.

'I'he arrangement of elements here disclosed involves an improvement which may be used to advantage in connection with the modification of a superheater which has been installed with all of its superheater coils uniformly spaced at both ends of the superheater.

When the superheater elements illustrated in Fig. 9 are installed, they may be placed in such positions that the superheater coils are uniformly spaced at each end. Subsequently, the ends of the tubes adjacent the uptake headers may be flexed so as to bring the-tubes into such a grouping as that illustrated in Fig. 9 and also in Fig.v5. Tbesuperlieater tubes may be held in this grouping when such movable dempers as those of the present case are provided, or means may be provided for changing at will the arrangement of tubes. whereby they are varied from the grouped arrangement of Figs. and 9 to attain a uniform spacing at each end of the superheater.

Although the present invention contemplates changes in tbe effectiveness of parts of the superheating surfaces so that some partsl will absorb more heat than others, there will be no resulting excessive non-uniformity of superheat. All of the separate superheater tubes discharge into a common outlet header in which steam mixing takes place to equalize the superheat. At maximum bciler ratings there may be no such mixing but mixing take place at lower ratings even though the superheating surface remains conetant at all ratings.

As indicated in Figs, l and 5 of the drawings, the lower tube l5 of the superheat controller is connected to the U-bends of the lower tubes of each of the movable coils lil, 12, 'I4 and 76, While the upper tube 54 is connected to the uppermost of the same coils.

Fig. '7 illustrates clearly the manner in which the tube it is connected to the loop 9? of one of the superheater coils. A pin 92 extends through the lug ed and through two parallel members 42 to maintain a pivotal support for the superheater coil.

While the invention has been illustrated by the disclosure of a particular modification, and the description has related to such modification, it is to be appreciated that the invention is not limited thereto, but is of a scope commensurate With the scope or the subjoined claims.

What is claimed is:

l.. In combination, a bank of boiler tubes, a bank of superheater tubes arranged in spaced groups beyond the boiler tubes relative to gas yiiovv, means lfor movably supporting some of the superheater tubes, tube shields carried by said movable tubes and arranged so as to be positioned in front of some of the fixed tubes, and uid cooled superheat control mechanism connected to the movable tubes for causing the shielding of increasing areas of the superheater tubes as the spacing of the superheater tubes is varied.

2. In combination, a bank of Water tubes affording boiler heat absorbing surfaces, a superheater including tubes subjected to hot gases, movable plates xed to some of the superheater tubes and arranged to shield others of the superheater tubes, and control mechanism connected to the tubes to which the plates are fixed for moving the plates.

3. In combination, a bank of boiler tubes, a bank of superheater tubes arranged in spaced groups beyond the boiler tubes relative to gas ilovv, means for supporting some of the superheater tubes for movement transversely of the gas pass in which the superheater is located, tube shields carried by` said movable tubes and arranged so as to be positioned in front of some of the non-movable tubes, and superheat control mechanism `connected to the movable tubes for shielding decreasing or increasing areas of the superheater tubes as the control mechanism is operated.

4. In combination, a bank of inclined tubes constituting a steam generating section of a water tube steam boiler and extending across a gas pass, a superheater located beyond said tubes relative to heating gas flow and composed of groups ci bent tubes having their inlet and outlet ends at the same side of the gas pass, means for supporting the inlet and outlet ends of the superheater tubes in uniformly spaced arrangement, a'superheat controller supportl at the other side of the gas pass, connections between the support and intermediate sections ofI the superheaterl tubes for moving some of the superheater tubes to vary gas iiow resistance, and plates carried by the movable tubes and extending from one group to the other when the movable tubes are at one limit of their movement.

CHARLES U. SAVOYE.

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