JPH0256593B2 - - Google Patents

Description

[Detailed Description of the Invention] [Technical Field of the Invention] The present invention relates to a vertical multi-tube falling liquid film heat exchanger, in particular, an inner tube or a cap is provided at the upper end of the tube, and the liquid is guided to the inner surface of the heat transfer tube. The present invention relates to an improved heat exchanger that forms a falling film and thus improves heat exchange efficiency.

[Background of the Invention] A multitubular falling film heat exchanger is surrounded by a body and has heat transfer tubes arranged between two spaced apart tube plates. The body is provided with an inlet and an outlet so that a suitable heat exchange liquid or gas can be circulated within the body to cool or heat the liquid flowing within each tube.

Each end of the heat transfer tube is left open or exposed so that it can be used for certain process operations. If another process is to be carried out, one or both ends can be surrounded by a header for liquid retention. It is optional whether the header is provided with a removable lid or an inspection hole.

Although shell-and-tube heat exchangers are commonly used to heat liquids, they can also be used to cool liquids. Shell-and-tube heat exchangers of the type described above can be used as refrigeration exchangers for purifying fresh water from salt water and seawater, for concentrating vegetable and fruit juices, and for carrying out industrial crystallization processes. When the liquid flows into each heat transfer tube, it is sufficiently cooled and solids are precipitated from the liquid. Therefore, when seawater is cooled, ice forms, which can be separated and
By washing and dissolving, drinking water is obtained. When fruit or vegetable juices are deep cooled at the same time, ice is formed which can be removed to form concentrated juices.

Refrigeration heat exchangers of the type described above may use any cooling liquid on the body side to cool the liquid flowing downwardly within the heat transfer tubes. The liquid can be supplied from one end of the refrigeration heat exchanger and discharged from the other end in a generally unidirectional flow state. Suitable cooling fluids include refrigerant gases such as ammonia and Freon.

Whether heat exchangers are used to heat or cool process fluids, it is desirable to be able to control the thickness and uniformity of the falling film within each heat transfer tube. In general, the fluid supply to each tube is often uneven, with some tubes having more fluid and others less than the amount of fluid required for optimal heat exchange. Therefore, good results cannot be obtained simply by supplying a sufficient amount of liquid to each heat transfer tube. Accordingly, there is a need for an apparatus that supplies treatment liquid to the heat transfer tubes so that the thickness of the falling film formed on the inner surface of each heat transfer tube is uniform and uniform.

SUMMARY OF THE INVENTION In summary, a falling film heat exchanger according to the present invention comprises a body connected to vertically spaced, horizontally disposed upper and lower circular tube sheets; a plurality of parallel heat exchange tubes each passing through and connected to a hole in the tube sheet; means for supplying heat exchange liquid to the body side of the heat exchanger; and means for supplying heat exchange liquid from the body side of the heat exchanger. a means of discharging;
a liquid distribution box located above the upper tube plate, a means for supplying a feed liquid to the liquid distribution box, and a member within the upper end of each heat exchanger tube, the member directing the liquid flowing from the distribution box to the heat exchanger tube. It can be said that the heat exchanger is equipped with a means for ensuring that the liquid introduced to the inner wall and flowing into the heat transfer tube always passes through the member.

The member for directing the liquid to the inner wall of the heat transfer tube includes a plurality of spaced apart holes, the dimensions of which are such that the downwardly flowing liquid is diffused and diverted to form a continuous downwardly flowing liquid layer. It is desirable to set the value to such a value that it can form .

To explain in detail, the above-mentioned member has a resistance against the inner surface of the heat exchanger tube when measured from a plane parallel to the axis of the heat exchanger tube.
It is desirable to direct the liquid at an angle of inclination of about 0° to 80°. More specifically, it is currently considered best for the angle of inclination to be in the range of about 20° to 80°, particularly in the range of 40° to 80°.

The member may be a short encircling tube with its lower end closed, except for means such as holes for introducing liquid into the inner wall of the heat transfer tube.

The member is also in the form of an encircling cap over the end of the heat exchanger tube, the cap having a concave central portion with radially arranged holes through which liquid flows to cover the heat exchanger tube. It may also be possible to contact the inner wall of the The cap may include a downwardly depending cylindrical skirt portion that fits around the upper end of the heat exchanger tube. Alternatively, the skirt portion can be fitted onto the inner surface of the end of the heat exchanger tube.

DESCRIPTION OF THE EMBODIMENTS The present invention will now be described in detail with reference to the accompanying drawings, in which identical elements or parts have been designated by the same numerals in the various drawings to the extent considered appropriate.

Referring to FIG. 1, heat exchanger 10 includes a vertical cylindrical metal body 12 connected to tubesheet 14 and lower tubesheet 16. The conical end 18 connected to the lower end of the body 12 is provided with an outlet 20;
The liquid is discharged from the heat exchanger tube side of the heat exchanger 10 through the outlet.

Extending upwardly from the edge of the upper tubesheet 14 is a wall extension 28 of the fuselage 12;
forms the partition chamber 30 of the flow distribution box. The inlet 32 communicates with an opening in the wall extension 28 and provides means for supplying liquid into the compartment 30.

Each of the plurality of heat transfer tubes 36 positioned in the longitudinal direction and arranged in parallel is connected to the upper tube sheet 14 and the lower tube sheet 1.
6 and connected to longitudinally aligned holes in the tube sheets 14 and 16.

Liquefied refrigerant gas can be supplied to the body side of the refrigeration heat exchanger 10 through the opening 22 . Refrigerant vapor is exhausted from the upper opening 24, which is located partially or completely above the refrigerant level 26. A plate 40 is attached to the body 12 below the refrigerant opening 22. The plate 40 has a hole 42 directly larger than the outside diameter of the heat transfer tube through which the heat transfer tube 36 extends. Due to the large size of the holes 42, an annular opening is formed around each tube 36 through which liquid refrigerant flows downwardly to wet the outer surface of each tube. The dimensions of the holes 42 are such that the liquid refrigerant flowing downwardly along the outer surface of the heat transfer tube forms a film. A portion of the refrigerant vaporizes and is discharged from the nozzle 96. The remainder of the refrigerant collects at the bottom of the heat exchanger and exits through nozzle 98. The upper opening 24 is used to drain excess vapor and refrigerant from above the plate 40.

The above description relates to the combination of a film of refrigerant flowing vertically down the outside surface of the heat transfer tube and a film of slurry liquid flowing vertically down the inside surface of the heat transfer tube. It is possible to combine the membrane flowing down the inner surface of the heat exchanger tube with a boiler or other device on the body side.

Plate 50 constitutes the bottom of the diverter box. The plate 50 has a plurality of holes through which the flow branch tubes 52 are suspended downwardly in alignment with the heat transfer tubes 36. The outer diameter of the branch tube 56 is smaller than the outer diameter of the heat transfer tube 36. Therefore, the lower end of the branch tube 52 is connected to the heat transfer tube 36.
can be extended within the upper edge of the. Each branch pipe 52
The lower end of is closed with a plate 54. A plurality of radially located horizontal holes 56 (FIGS. 1 and 2) are formed at the lower end of each branch pipe 52. Through the hole 56, the feed liquid in the compartment 30 is discharged laterally and contacts the inner surface of the heat transfer tube 36. As the liquid flows downward, it rapidly diffuses and forms a continuous circumferential layer or film along the inner surface of the heat exchanger tube 3.
6 can provide the maximum surface area for heat exchange with the refrigerant on the fuselage side.

The number and size of the holes 56 in each branch tube 52 are set to such a value that a desired continuous film can be formed in the heat transfer tube 36. The supplied liquid is water, and the diameter of the heat transfer tube 36 is approximately 5.08 mm.
cm (2 inches), the number of holes in each diverter tube 52 may be approximately 10 to 16, and the diameter thereof may be approximately 1.27 mm (0.05 inch) to 3.81 mm (0.15 inch). It should also be understood that the flow rate of liquid through the holes can be adjusted by the amount of supply liquid in the compartment 30 and its pressure.

3 and 4 show another embodiment of the invention. A plurality of heat transfer tubes 36 are arranged within the body 12. The upper ends of the heat transfer tubes 36 pass through the upper tube sheet 14 and are connected thereto. A diverter box 62 is located above the tube plate 14. The diverter box 62 has a vertical cylindrical wall 64 and a removable lid 34.
and the tube plate 14 and surrounds the partition chamber 66. Feed liquid is supplied through inlet 32 and excess feed liquid is discharged through outlet 68. With this arrangement, the liquid head within the partition is always kept constant and the flow rate of the liquid supplied to the heat transfer tubes 36 can be adjusted.

Attached to the top of each heat transfer tube 36 is a feed liquid diverter cap 70 (FIGS. 3 and 4). Each cap 70 includes a circular skirt 72 surrounding the top of the heat transfer tube 36 and a downwardly directed frustoconical portion 74 that fits into the upper end of the heat transfer tube 36. The truncated conical portion 74 has holes 7 arranged radially at equal intervals.
6 is formed so that the supply liquid can be guided to the inner surface of the heat transfer tube 36. Above hole 76
has an angle of inclination of about 35° as measured downward from a line horizontal to the axis of the heat transfer tubes 36.

Another embodiment of a distribution cap according to the invention is shown in FIG. Similar to the embodiment shown in FIGS. 3 and 4, in this embodiment the diverter cap 80 has an upper peripheral end connected to a downwardly extending skirt 84 and a circumferentially spaced frustoconical body portion 82. In addition, the skirt 84 includes an anchoring ledge 86 at the top edge of the heat transfer tube 36. Even if the skirt 84 fits within the upper end of the heat transfer tube 36, the shelf 86 prevents the diverter cap 80 from moving completely into the heat transfer tube 36. A plurality of holes 88 are radially formed in the truncated conical body portion 82 , and the holes 88 guide the supply liquid to the inner surface of the heat exchanger tube 36 , and when the supply liquid is discharged from the holes and diffused, it spreads around the circumference of the heat exchanger tube 36 . It completely wets the surface and flows downward, adhering to the surface.

Another embodiment of the diverter cap 90 is the sixth embodiment.
It is shown in the figure. The cap 90 is almost disk-shaped with both sides flat and parallel. The cap 9
A ledge 92 on the upper periphery of the heat exchanger tube 36 allows the cap to be attached to the upper end of the heat exchanger tube 36 without having to fit the cap completely into the heat exchanger tube. The cap 90 includes a plurality of equally spaced radially downwardly oriented holes 94 that direct the feed liquid to the inner surface of the heat transfer tube 36.

Although the invention can be applied to both heating and cooling feed liquids, it is particularly useful when the heat exchanger is used as a refrigeration heat exchanger, such as in the purification of potable water from brine. Because ice floats, all ice in the recirculated feed liquid collects in the upper portion of the liquid in the diverter box. Ice can be discharged along with excess supply liquid using a structure such as that shown in FIG. In this way, the amount of ice that flows with the feed liquid through the holes in the distribution cap is minimized, thus reducing the risk of the holes becoming clogged.

Although the holes in the diverter cap shown in the accompanying drawings are circular in cross-section, they may be square, triangular, rectangular or oval in cross-section. Furthermore, the holes do not need to be formed in the same plane as the axis of the heat exchanger tubes 36.
The holes are sloped in the same or opposite directions so that when the liquid is ejected and impinges on the inner surface of the heat transfer tube 36, it swirls, thus promoting diffusion and forming a circumferential film more quickly. be able to.

The diverter cap and heat transfer tubes can be made of any suitable material. When used in refrigeration heat exchangers, they can be made of metal or polymeric materials. It can also be machined or molded into the desired size and shape.

Since the heat exchange efficiency is improved by forming a falling film without completely flowing the supplied liquid into the heat transfer tube 36, the amount of liquid projected by the pump can be reduced, and therefore the required horsepower of the pump can be reduced. Can be done. By using the liquid distribution means described above,
By changing the size and number of holes without changing the model of the flow dividing means itself, it can be done according to the type of liquid to be treated.
The amount of flow of the falling film can be easily adjusted.
Of course, the supply liquid head and pressure within the flow divider box can be varied to increase or decrease the amount of liquid flowing down the heat transfer tubes.

The device described above is characterized by components that are easy to manufacture, relatively inexpensive and employ superior materials and construction methods.

The above detailed description has been provided only to provide a clear understanding of the subject matter of the present invention, and the above description should not be considered as limiting in any way. Therefore, it goes without saying that other embodiments can be easily devised by those skilled in the art.

[Brief explanation of drawings]

FIG. 1 is a partially cut away elevational partial cross-sectional view of a heat exchanger according to the present invention, and FIG. 2 is a partial cross-sectional view showing a liquid supply branch pipe projecting and fitting into the upper end of the heat exchanger shown in FIG. 3 is an enlarged elevational view; FIG. 3 is a partially cut-away elevational partial cross-sectional view of the top of the heat exchanger showing the liquid diverter caps with skirts outside the top ends of the heat exchanger tubes; FIG.
FIG. 5 is a cross-sectional view of another embodiment of the liquid supply diverter cap showing the skirt fitted inside the heat exchanger tube, and FIG. 6 is a cross-sectional view of the upper end of the heat exchanger tube. FIG. 3 is a longitudinal cross-sectional view of the overlying disc-shaped liquid supply diverter cap;

Claims (1)

[Scope of Claims] 1. A heat exchanger body connected to upper and lower circular tube sheets arranged horizontally and spaced apart from each other, and a plurality of heat exchanger bodies each passing through a hole in the tube sheet and connected to the hole. parallel heat transfer tubes positioned longitudinally, means for supplying heat exchange fluid to the heat exchanger body side, means for discharging heat exchange fluid from the heat exchanger body side, and located above the upper tube sheet. a liquid distribution box; a means for supplying a supply liquid to the distribution box; and a member located at the upper end of each heat transfer tube, the member guiding the liquid flowing from the distribution box to the inner wall of the heat transfer tube; A falling film heat exchanger, characterized in that it includes means for ensuring that the liquid flowing into the heat tube always passes through the member. 2. The means for guiding the fluid to the inner wall of the heat exchanger tube includes a plurality of holes arranged at intervals in the member, and the liquid flowing downward through the dimensions of the holes is diffused and divided so that the liquid flows to the inner wall of the heat exchanger tube. A falling liquid film heat exchanger according to claim 1, characterized in that the value is set such that a continuous liquid layer flowing downward can be formed. 3. The falling film heat exchanger according to claim 2, wherein the holes have an inclination angle of approximately 0° to 80° as measured from a plane horizontal to the axis of the heat transfer tube. .