US1782435A - Apparatus for cooling fluids - Google Patents

Description

Nov. 25, 1930. H. F. MERRIAM APPARATUS FOR COOLING FLUlDS Filed Nov. 9, 1926 Heiz Patented Nov. 25, 1.930

UNITED STATES PATENT .OFFICE HENRY F. MERRIAM, 0F WEST ORANGE, NEW JERSEY, ASSIGNOR T0 GENERAL CHEMI- CAL COMPANY, 0F YORK, N. Y., A CORPORATION 0F NEW YORK APPARATUS FOB. COOLING FLUIDS Application led November This invention relates to a process of transferring heat from one iuid to another and particularly to the cooling of one gas by another.

In many chemical processes it becomes necessary to cool gases containing corrosive vapors or considerable amounts of moisture. If the cooling operation is not carefully controlled these vapors Will condense out of the gas stream in the form of a liquid and corrode the equipment. For example, in the contact process for the manufacture of sulfuric acid, particularly Where the source of sulfur is brimstone, asin the U. S. patent to Merriam 1,384,566, it becomes necessary to abstract considerable' quantities of heat from sulfurous gases containing moisture and some sulfur trioxide. The most common procedure for cooling these gases is to pass them `through heat transferrers constructed of steel through which air or other cooling fluid is circulated as the cooling medium. It the temperature of the sulfurous gases is lowered at .any point in the heat transferrer below that temperature at which the contained sulfuric acid begins to condense, serious corro'- sion of the transferrer tubes will result and necessitate expensive repairs and replacement of the corroded apparatus. This Acondensation temperature is frequently rather high, being for example around 400o F. for a gas containing about 0.5 gra-m of moisture ner cu. ft., which corresponds roughly to the gas produced when burning brimstone With undried air having a high humidity. If localized cooling occurs in the heat transferrer at the point Where the cooling medium initially contacts with the heat transferrer tubes. such that the temperature of the tubes falls below the temperature given in the above example, condensation of sulfuric acid will occur and result in corrosion at this point.

Various methods have been proposed for preventing this condensation, for example, by using preheated steam having a temperature above 400 F. as the cooling medium, as shown in the U. S. patent to Bezanson 1,542,- 488. Such methods require the installation of expensive apparatus and are objectionable 9, 1926. Serial N0. 147,245.

for this reason. It is anyobject of my invention to overcome the disadvantages above given in a simple manner requiring but slight modificationof present types of heat transfer apparatus.

A further object of my invention is the provision of an improved process of and apparatus for cooling a fluid to a predetermined temperature by means of a cooling medium havingan initial temperature below such predetermined temperature, lwhereby increased heat transfer efficiency is obtained.

I have illustrated an apparatus embodying my invention in the accompanying drawings, in Which:

Fig. 1 represents an elevation view in crosssection through this apparatus, and

Fig. 2 represents a cross-section view upon the line 2-2 of Fig. 1.

The apparatus as shown comprises a. steel container shell 1 having end Walls 2 and 3 and tube sheets 4 and 5 at each end thereof. The tube sheets 4 and 5 form in conjunction with the end Walls 9. and 3 a header or distributing section at each end of the container for the entering and leaving fluid being cooled. These headers are provided withan outlet 6 and inlet 7, respectively. .Secured in the tubesheets and passing through the shell are a plurality of heat transferrer tubes 8, forming a tube nest through which the fluid to be cooled is passed. The shell 1 and tube sheets 4 and 5 form a container through which the cooling fluid is circulated toexert a cooling action upon the outer surfaces'of the transferrer 'tubes 8. The container is provided at its lower end with a plurality of openings 9 spaced uniformly around the circumference of thc container and through Which the cooling Huid enters. The openings 9 communicate with an annular chamber surrounding the container formed by the bustle or distributing pipe 10. The cooling fluid enters the bustle pipe from the supply pipey 1l; vthe lflow being controlled by Vthe butterfly valve 12, and leaves the container through the outlet 18. In this same endiof the container is also placed a partition or Wall 14 forming with the tube sheet 5 a compartment connected with the outlet 13.

This wall 14 is also formed as a tube sheet and has tubular ballles 15 attached thereto and placed concentrically of the tubes 8. The baliles l5 extend from the wall 14 in the direction of the tube sheet 4, thus forming a passageway 16 between the tubes 8 and baffles 15 opening into the compartment between wall 14 and tube sheet 5 at one end and the interior of the container at the other end.

As above stated, the fluid to be cooled passes through the tubes 8 in the direction indicated by the arrows. The cooling fluid, which willordinarily be air, enters from the supply pipe 11 into the bustle pipe 10, and from here is uniformly distributed through openings 9 into the container and caused to circulate around the baffles 15 and then flow upwardly through the container as indicated by the arrows. The baffles 15 will be heated by transfer of heat from the hot gases passing through the tubes 8, and this heat will of course be transferred to the cooling fluid during its passage along the baliles 15 through the passageway formed by the baffles and container wall 1. The temperature of the cooling fluid will` thus be raised by the time it reaches the upper end of the baffles 15 and before it initially contacts with the outer surfaces of the heat transferrer tubes 8. The thus preheated cooling fluid then passes downwardly through the passageways 16 formed by the baffles 15 and tubes 8, passes into the compartment between wall 14 and tube sheet 5, and thence to outlet 13. During the passage of thecooling fluid through the passageways 16 it will of course exert a cooling action on the tubes 4 and thus cool the hotl gases-to whatever temperature is desired.

I have illustrated the streams of fluid to be cooled and cooling fluid as passing in counter-current flow. Likewise, the streams of cooling ffuid upon opposite sides of baffles 15 pass in counter-current flow. This arrangement results in greater heat transfer elliciency than would co-current flow and is preferred for this reason.

The distance between the tube sheets 4 and 5 and consequently the length of the baffles 15 will be made sufliciently great to bring about a general overall uniformity of temperatiu'e conditions in the cooling fluid by the time it reaches the upper end of the baflles and contacts with the transferrer tubes. For operation with air as a cooling fluid upon hot sulfurous gases in a Contact sulfuric acid system, and using an apparatus of the general design shown in the drawing, I have obtained satisfactory operation with an apparatus in which the length of the bafes was approximately equal to the diameter of the container shell. However, it should be understood that the dimensions of the apparatus will vary with particular operating conditions and my invention is not limited to the particular embodiment illustrated in the drawing.

It will be seen that in accordance with my invention a transfer of .heat takes place from the hot gases to be cooled to the streams of cooling fluid passing through the passageways 16, and simultaneously with this there is a transfer of heat from these streams to the streams of cooling fluid passing upwardly aroundthe ballles 15. The amount of heat in the cooling fluid in the passageways 16 is thus being constantly loweredhby the cooling action of the entering cooling fluid passing upwardly outside of the batlles 15. The temperature of the cooling fluid in passageway 16 is thus much lower, particularly in the lower portion of the passageway, than if this simultaneous supplemental cooling action were not taking place. This of 'course results in a much greater heat transfer elficiency than if a cooling medium preheated to the temperature obtaining at the entrance to the passageways 16 were alone used, and moreover permits the use of air at atmospheric temperature to be used without necessitating the employment of elaborate prelieating apparatus.

It will be clear that by Varying the amount of entering coolingfluid by means of the valve 1:2 the temperature to which the cooling fluid will be preheated by the time it initially contacts with the tubes 8 may be varied. If the quantity of cooling fluid is reduced, it will of course be preheated to a higher temperature, and likewise if the quantity is increased the amount of preheating will be reduced. The system is thus flexible and capable of close control to maintain any desired temperature in the cooling fluid at its point of initial contact with heat transferrei' walls having the fluid to be cooled in contact with the opposite surfaces thereof. Localized cooling of the heat transferrer surfaces is thus avoided and the objectionable condensation of corrosive liquids effectively prevented. i

I desire it to be understood that my invention is not confined exclusively to the cooling of gases but may be applied advantageously to any fluid where it is desired to maintain such fluid above a predetermined temperature. For example, the invention might be advantageously applied to the cooling ofconcenti-ated salt solutions, with which, if the temperature of the solution in the upper portions of the tubes 8 were allowed te fall below a certain, point, crystallizing might commence-upon the surfaces of the tubes and in a short time clog them and prevent the flow lof liquid therethrough. kBy means of my invention the tubes8 may be maintained above the crystallizing temperature and this difficulty overcome.

I claim:

l. In a heat ti'ansferrer, thecombination ends of the auxiliary ported by said additional tube sheet, imper-.

baille tubes and the tubes of the tube nest,

andan adjustable valve controlling the fiow of the coolin fluid and set to admit an amountof coo ing fluid which will produce a predetermined temperature condition lin the coolin fluid at the point where such cooling fluid first comes into direct contact with the tubes constituting the tube nest.

2. In a heat transferrer, a container, a nest of tubes extending through said container and open for the passage of a fluid to be cooled, an admission port to the interior ofthe container, auxiliary baffle tubes of larger diameter surrounding the individual tubes of the tube nest and spaced therefrom, an outl let port from the container, said ports, baflle tubes, and container being constructed andl arranged to cause the entering cooling fluid to first contact with the outer'surfacesI ofthe baille tubes, then to pass through the passageways between the tubes of the tube nest and the baffle tubes, and then to discharge through the outlet port, and an adjustable valve controlling-the flow ofthe cooling medium and set to admitan amount of cooling fluid which will produce a predetermined temperature condition in the coolin Huid at the point where such cooling flui first comes into direct contact with the tubes constituting the tube nest.

3. In a heat transferrer, the combination of a nest of tubes open for the passage. of a fluid to-be cooled, impervious tubesheets to support opposite end portions of the tubes of the tube nest, auxiliary tubes of larger diameter surrounding individual tubes of the tube nest and spaced between the said tube sheets, an additional tube sheet for supporting' in position said auxiliary tubes, saidadditional tube sheet bein spaced from one of the tube sheet/s of the tu e nest to form therewith an outlet passage for cooling fluid, an admission yport to the interior of the tube nest'space ai*- ranged to admit a cooling fluid near those tubes which are supvious walls for preventing the escape of cooling Huid from the tube nest spa'ce except through the annular s aces between the tubes of the tube nest and a ong the inner surfaces of the auxiliary tubes to the ends of the latter adjacent their supporting tube sheet, and an adjustable valve controllin the flow of the cooling medium vinto the tu e nest space and adajfted to be set to admit an amount of cooling uid which will produce a predetermined temperature condltion in the cooling Huid within the tube nest space at the point where such cooling fluid first comes into di-l rect ,contact with the tubes constituting the tube nest. I

4. In a heat transferrer, the combination of a nest of tubes open for the passage of a fluid to be cooled, impervious headers to supportv opposite end portions of the tubes of the tube nest, auxiliary tubes of larger diameter and surrounding individual tubes of the tube nest and open at their tops and bottoms betweenthe headers of the tube nest, an admission port to the interior of the tube nestl spacebetween its headers arranged to admit a cooling fluid near that part of the auxiliary tubes which is adjacent to the inlet end'of the hot fluid entering the tubes constituting the tube nest, means for reventing the escape of cooling fluid from t e tube nest space except through the annular s aces between the tubes of the tube nest an along the inner surfaces of the auxiliary tubes to that part of the latter where they are most closel adjacent to the entrance end of the hot fluid to the tubes of the tube nest, a passage for the escape of cooling fiuid from between the headers of the tube nest and. an adjustable valve controlling the flow of the cooling medium into the tube nest space and adapted to beset to admit an amount of cooling fluid tube nest space at the point where such coolinafluidfrst comes into direct contact with the tubes constituting the tube nest.

whereof, I aix my signature,

In testimony HENRY F. MERRIAM.

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