US2845907A - Apparatus for heating fluids - Google Patents

Description

Aug. 5, 1958 H. F. PAYNE ETAL APPARATUS FOR HEATING FLUIDS 6 Sheets-Sheet 1 Filed March 16, 1955 \w &\ Mm

HUGH FREDERICK PAYNE 8 FREDERICK WALTER BAUER BY Aug 5, 1958 H. F. PAYNE ETAL APPARATUS FOR HEATING mums e Sheets-Sheet 2 Filed March 16, 1955 I N V EN TORSa HUGH FREDERICK PAYNE FREDERICK WALTER BAUER BY WWW/ 4M 5, 1958 H. F. PAYNEETAL 2,845,907

APPARATUS FOR HEATING FLUIDS Filed March 16, 1955 6 Sheets-Sheet 3 INVENTORJ. 1 HUGH FREDERICK PAYNE a 4 FREDERICK WALTER BAUER Aug. 5, 1958 H. F. PAYNE ETAL 2,845,907

APPARATUS FOR HEATING FLUIDS 6 Sheets-Sheet 4 Filed March 16, 1955 FIG. 4.

INVENTORS. HUGH FREDERICK PAYNE a FREDERICK WALTER BAUER BY We TTOIQNEYS.

5, 1958 H. F. PAYNE EIAL 2,845,907

APPARATUS FOR HEATING FLUIDS Filed March 16, 1955 e Sheets-Sheet 5 INVENTORS. HUGH FREDERICK PAYNE 8 FREDERICK WALTER BAUER I I I O I I// I/ I 1958 H. F. PAYNE ETAL 2,845,907

APPARATUS FOR HEATING FLUIDS 6 Sheets-Sheet 6 Filed March 16, 1955 FIG. 6.

INVENTORS. HUGH FREDERICK PAYNE FREDERICK WALTER BAUER BY United States Patent APPARATUS FOR HEATING FLUIDS Hugh Frederick Payne, London, and Frederick Walter Bauer, South Croydon, England, assignors to John B. Pierce Foundation, New Haven, Conn, a corporation of New York Application March 1 6, 1955, Serial No. 494,645

Claims priority, application Great Britain March 22, 1954 4 Claims. (Cl. 122-275) This invention relates to apparatus for heating fluids and, more particularly, pertains to improved heat transfer structure for efficiently and uniformly heating temperature sensitive fluids.

' In heat transfer systems in which a temperature sensitive fluid is heated, care must be exercised to insure that the temperature of the fluid is not raised above a predetermined level at any point in the system, in order to prevent deterioration of such fluid. However, previously known heat transfer systems provided continuous heating pipes carrying the fluid which tended to substantially isolate certain fluid portions for an extended distance along the pipe, this arrangement permitting localized heating and excessive fluid temperatures. Accordingly, it is an object of the present invention to provide a heat transfer system in which fluids may be uniformly and efficiently heated Without excessively heating any localized portions of such fluid.

It is another object of the invention to provide heat transfer systems of the above character in which the fluid to be heated is thoroughly mixed one or more times during its circulation through pipe sections to preclude the excessive heating of any portion of the fluid.

It is a further object of the invention to provide heating systems of the above character in which the fluid in adjacent pipe sections travels in opposite directions in order to provide for more uniform and eflicient fluid heating.

It is still a further object of the invention to provide heat transfer structure formed by an enclosure whose interior walls are at least partially covered by sectionalized panels of pipes in which the fluid travels in opposite directions in adjacent sections, and a passage leading from the enclosure in which further fluid carrying pipes are disposed and heated by gases escaping from the enclosure.

These and further objects of the present invention are accomplished by circulating the fluid to be heated in one or more sectionalized panels of adjacent parallel pipes in which the fluid in traversing the panel or panels sequentially travels in opposite directions in adjacent sections, the panels preferably being heated by radiant heat.

In a preferred embodiment of the invention, the panels form at least part of the interior surface of an enclosure containing the heat source, a plurality of panels being joined in order to uniformly and efliciently heat the circulating fluid. Preferably, further pipes carrying the fluid circulated through the panels are disposed in an outlet passage communicating with the enclosure in order to extract heat from the hot gases escaping from the heat source found in the enclosure.

These and further objects and advantages of the present invention will be more readily understood when the following description is read in connection with the accompanying drawings in which:

Figure 1 is a plan view, partially broken away, of heat transfer apparatus constructed in accordance with the principles of the present invention;

Figure 2 is a longitudinal section of the apparatus shown in Figure 1 taken on the view line 2-2 looking in the direction of the arrows;

Figure 3 is another longitudinal section of the heat' in the direction of the arrows;

Figure 5 is another transverse section of the heat transfer apparatus taken on the view line 55 of Figure 1 looking in the direction of the arrows; and

Figure 6 is yet another transverse section of the heat transfer apparatus taken on the view line 66 of Figure 1' looking in the direction of the arrows.

Referring to an illustrative embodiment of the invention in greater detail with particular reference to the drawings, a box-like structure is formed of a floor 10, a roof 11, sides 12 and 13, a front wall 14 and a rear wall 15, each of these members preferably being formed of one or more layers of fire brick or similar heat resistant materials which will also preferably insulate the entire structure. In order to provide a strong rigid assembly, suitably positioned reinforcing channels 16 may be disposed on the members 11 to 15, inclusive. To provide access to the interior of the structure, openings 17 and 18 are provided in the front and rear walls 14 and 15, respectively, and closed by covers 19 and 20, respectively.

Suitably positioned on the floor is a heater 21 having three angled surfaces 22 with a plurality of openings 23 to permit the burning of oil or a gas mixture entering through an inlet 24, broken away for clarity. The flames at the openings 23 provide a uniform source of radiant heat effectively heating various elements explained in detail below. Obviously, other equivalent heaters fired by oil or by electrical means, for example, could be used in place of the gas heater 21.

As best shown in Figures 3 and 5, a panel 25 formed of a plurality of adjacently mounted parallel pipes 26 substantially covers the sides and forms a rear wall 25a of what will be termed an enclosure 27. In order to provid a substantially solid metallic wall to the radiant heat from the heater 21, diametrically opposed fins 28 are r formed on the pipes 26 and are closely spaced as clearly shown in Figure 5. However, the pipes 26 forming a lower portion of the rear wall 25a do not have the fins 28 mounted thereon, except at points near their extremities, in order to permit the hot gases generated by the heater 21 to escape past the wall 25a into a passage 30 and out a flue 31 in the roof 11 (Figure 2).

The pipes 26 communicate at their ends with headers 32 and 33 on opposite sides of the front wall 14, best shown in Figures 3 and 4, the header 32 being joined to a fluid inlet duct 34. A partition 35 (Figure 4) divides the header 32 into two substantially independent sections each having a number of the pipes 26 dictated by the particular structure. Thus, if the panel 25 was used independently, the sections would preferably be substantially equal. However, in this instance there are ten pipes in the lower section and five pipes in the upper section to equalize fluid circulation in a manner explained hereinafter. If desired, small vent holes 36 may be formed in the partition 35 to permit gases to flow therethrough. A number of vents 37 are also suitably positioned on the headers 32 and 33 and serve to remove gases found in the circulating fluids.

Any suitable means may be employed to support the panel 25 such as brackets 38 and 39 fastened in the sides 12 and 13, respectively. It should also be understood that the pipes 26 may be closely spaced together in which case the fins 28 would be unnecessary. In this event, the lower pipes could be spaced in 'order' to permit the escape of gases to the passage 30.

Substantially covering the interior surface of the roof of'the enclosure 27 are two panels 40 and 41 (Figure 1) formed of adjacent parallel pipes 42 and 43, respectively. Diametrically opposed fins 44 and 45 may be provided on the pipes 42 and 43, respectively, for the same purpose as the fins 28 used on the pipes 26. At their forward end, the pipes 42 and 43 are joined to a header 46, extending across the front end of the roof 11 and sectionalized at both sides by partitions 47 and 48, these being vented as discussed in connection with the partition 35 found in the header 32, if desired. Preferably, the partitions 47 and 48 divide the panels 40 and 41 into a substantially equal number of pipes. The header 46 may 'be vented by suitably positioned vents 49.

In order to circulate fluid through the pipes 42 and 43 in the panels 40 and 41, respectively, U-shaped sections 50 and 51 are provided to join the ends of the pipes 42 and 43, respectively. It will be apparent that instead of such U-shaped sections 50 and 51, headers could be provided at this end of the pipes 412 and 43 functioning in the same manner as the header 33 described in connection with the panel 25. Conversely, U-shaped sections could be substituted for the header 33 in the panel 25.

The panels 40 and 41 maybe supported in any desired manner such as by the brackets 52 and 53, respectively, fastened to the roof 11.

Referring to Figure 4, the header 46 is joined by an elbow pipe section 5 to the header 33 at one end, its other end being joined to a longitudinally extending relatively large diameter pipe 55 adjacent to the side 12. A short section of pipe 55a also joins the upper section of the header 32 to the header 46.

Vents 56 release gas from the pipe 55 which extends to a header 57 longitudinally positioned in the side 12 across the passage 30, as best shown in Figures 2, 3 and 6. Joined to the header 57 are a plurality of pipes 58 each formed with four reverse loops 59 in a vertical plane traversing the passage 30, the other end of the pipes 58 leading to a further header 60 in the upper portion of the side 13. A connecting tube 61 provided with a vent 62 (Figures 1 and 6) joins the header 60 to yet another header 63, lower in the wall 13 but slightly above the header 57, which communicates with a plurality of pipes 64 reversely looped by sections 65 in a similar manner to the pipes 58. Each of the reversely looped pipes 64 is in a vertical plane and slightly higher than the pipes 59, the pipes 64 and 59 alternating across the passage 30, as clearly shown in Figures 2 and 3. The other ends of the pipes 64 communicate with a header 66 (Figures 1. 2 and 6) in the wall 12 slightly above the header 60, the header 66 being vented by a vent 67 and constituting the outlet for the heated fluid.

Before examining the operation of the present invention, it should be understood that when the transfer of heat from the heat source to the fluid proved to be desirably etficient in prior heat transfer systems, there was often excessive localized heating. Such localized heating resulted in portions of the heated fluid being raised above a selected temperature. In instances in which temperature sensitive fluids were heated, such localized heating deteriorated such fluids.

'In order to achieve both efficient heating and preclude excessive localized heating effects, it is necessary to control both the rate of heat input per unit area of heating surface and the coetficient of heat transfer from the heating surface to the fluid being heated, in relation to the temperature of the fluid being heated.

Referring more particularly to the operation of this embodiment of the invention, the fluid to be heated by means of the heater 21 enters the heat transfer system at the inlet duct 34- leading to the header 3?; (Figures 2 and 3). The fluid initially flows through only the pipes 26 in the lower section of the panel 25 due to the partition 35 (Figure 4). It should be noted that the flow direction of the fluid is shown by arrows in several figures of the drawing. After flowing through the lower pipes 26 around three sides of the enclosure 27, the fluid reaches the header 33 where it is thoroughly mixed to effectively equalize the temperature of localized portions of the fluid in the lower pipes 26. From the header 33, the fluid is divided to follow alternate paths, part of the fluid returning to the upper portion of the header 32 through the pipes 26 in the upper section of the panel 25 while the remainder of the fluid is fed through the elbow 54 to the header 46. Due to such divided fluid flow, it is preferable to have a greater number of the pipes 26 in the lower section than in the upper section of the panel 25 to equalize the fluid circulation. Thus, ten pipes are found in the lower section and five pipes in the upper section in this instance since there are five pipes in each section of the panels 40 and 42.

The fluid furnished to 'the header 46 flows through the pipes 43 in the panel 41 due to the partition 48, such pipes being joined by the U-shaped sections 51. After flowing through the pipes 43, the fluid returns to the header 46 where it is again thoroughly mixed and flowed through the pipes 42 comprising the panel 40. The fluid then returns to be mixed in the header 46 on the other side of the partition 47, the fluid flowing therefrom to the longitudinally extending pipe 55. In addition, the fluid returned to the upper portion of the header 32 flows through the connecting pipe 55a to the header 46 where it joins the fluid flowing to the pipe 55.

The fluid heated in the panels 25, 40 and 41 flows through the pipe 55 to the header 57, it being evident that during this flow, the fluid is again thoroughly mixed to equalize any diflerenc'es in heating in the previous panels it has traversed. From the header 57, the fluid passes through the pipes 58 to the header 60 where it is again thoroughly mixed and flowed through the connecting tube 61 to the header 63. Finally, the heated fluid flows through the pipes 64 to the header 66 and exits therefrom at the selected temperature.

The pipes in the panels 25, 40 and 41 are, in this embodiment of the' invention, evenly heated by the radiant heat from the source 21 found in the enclosure 27. In addition, the gases from the enclosure 27 escape through the passage 30, as shown by the arrows in Figure 2, and heat by conduction the pipes 58 and 64. It is apparent that this arrangement efliciently uses the heat source 21 since not only does the radiant heat serve to heat the fluid but also the escaping gases give up much of their heat to the fluid.

In a typical heating operation which may be performed with the present invention, it may be necessary to heat a temperature sensitive liquid to a temperature of 600 F. In this process, it will be assumed that it is undesirable to have any surface in contact with the liquids at a temperature in excess of 640 F., due to the nature of the liquid. In order to meet these conditions where the rate of heat transfer to the surfaces containing the liquid is 16,000 B. t. u.s per square foot hour, the coeflicient of heat transfer from these surfaces to the liquid must be at least 400 B. t. u.s per square foot hour F. This is achieved by providing selected flow velocities of the liquid past the heat transfer surfaces and, at the same time, providing for effective flow distribution and mixing as described above so that no individual stream of the liquid being heated reaches a bulk temperature appreciably in excess of the final desired temperature of 600 F. The above is, of course, illustrative of the heating operations which may be carried out in the typical embodiment of the invention herein described.

It is apparent that a heat transfer system constructed in accordance with the principles of the present invention provides for efficient heating of a fluid without excessive localized heating which deteriorates certain fluids.

To this end, provision is made for successive mixing of the fluid for temperature equalization purposes after it has traversed certain sections of heating pipe.

It will be understood that the above-described embodiments of the invention are illustrative only and modifications thereof will occur to those skilled in the art. For example, individual panels may be provided for each of the interior surfaces of the enclosure 27 having headers at each end similar to the panel 25 or alternatively, panels similar to panels 40 and 41 may be used for the interior surfaces. Therefore, the invention is not to be limited to the specific apparatus disclosed herein but is to be defined by the appended claims.

We claim:

1. Heat transfer apparatus for heating fluids comprising an enclosure including a plurality of interior surfaces, radiant heating means in said enclosure, a first panel of first adjacent parallel pipes extending along a plurality of said interior surfaces, a first elongated header laterally partitioned to provide an inlet section to receive fluid and an outlet section to discharge heated fluid, an inlet pipe communicating with the inlet section of the first header, a first group of adjacent first pipes communicating at their one ends with the inlet section of the first header, a second group of adjacent first pipes communicating at their one ends with the outlet section of the first header, a second elongated header communicating with the other ends of said first pipes, a second panel of second adjacent parallel pipes extending along another of said interior surfaces, a third elongated header laterally partitioned to provide inlet and outlet sections, first and second groups of adjacent second pipes communicating at their one ends with the inlet and outlet sections of the third header, respectively, means joined to the other ends of said second pipes interconnecting said first and second groups of said second pipes to provide fluid flow in opposite directions in said -first and second groups of said second pipes, a pipe joining the second header to the inlet section of the third header to provide fluid flow between said first and second panels, an outlet pipe, and

pipe mean-s providing a direct path for fluid heated in the first panel from the outlet section of the first header to the outlet pipe and a direct path for fluid heated in the second panel from the third header to the outlet pipe, so that a portion of the fluid flowing into the heat transfer apparatus through the inlet pipe is heated in the first panel and another portion of the fluid is heated in the first group of first pipes in the first panel and in the second panel.

2. Apparatus as defined in claim 1, wherein the first panel extends along three vertical interior surfaces of the enclosure, the second panel extends along the interior surface defined by the roof, and said means joined to the other ends of said second pipes comprises a plurality of U-shaped sections joining the other ends of said first and second groups of said second pipes.

3. Apparatus as defined in claim 1, in which a passage is provided from said enclosure to permit the escape of heated gases produced by said heating means, third pipes in said passage heated by the escaping gases, and pipe means joining the first header and the third header outlet sections to said third pipes to carry the heated fluid from the first and second panels to said third pipes.

4. Apparatus as defined in claim 1, wherein longitudinally extending heat absorbing diametrically opposed fins are joined to a plurality of said first and second pipes, the longitudinal edges of the fins in adjacent pipes being closely spaced so that the first and second panels present a substantially closed wall to the radiant heating means.

References Cited in the file of this patent UNITED- STATES PATENTS 1,082,312 Fouque et al. Dec. 23, 1913 1,814,423 Albert July 14, 1931 1,890,170 Van Brunt Dec. 6, 1932 2,266,291. Young Dec. 16, 1941 2,403,017 Nordlund July 2, 1946 2,578,332 Williams Dec. 11, 1951

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