US2988334A - Heat exchange tank - Google Patents

Description

June 13, 1961 A. E. BUSH EIAL HEAT EXCHANGE TANK 2 Sheets-Sheet 1 Filed Sept. 21, 1959 3mm hm .2 9 k MS INVENTOR$ N/CKOLA 5 L. VA CANO ALBERT E. BUSH 14 TTORN E 5 June 13, 1961 A. E. BUSH EIAL HEAT EXCHANGE TANK Filed Sept. 21, 1959 2 Sheets-Sheet 2 INV NTOR.

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2,988,334 HEAT EXCHANGE TANK Albert Bush, 5063 Harold Place NE, and Nickolas L. Vacano, 3520 Conover St., both of Seattle, Wash.

Filed Sept. 21, 1959, Ser. No. 841,122 8 Claims. (Cl. 257-208) This invention relates to improvements in tanks wherein means is provided for controlling the temperature of the contents of the tank. In the following description and explanation, we will refer more particularly to tanks used in making or processing beer, however, it shall be clearly understood that our new and improved tank design is not limited to use in breweries but the tanks may be used in milk processing, handling of chemical solutions or any other use wherein it is desired to raise, lower or control the temperature of the contents of the tank during proc- -essing or storage.

In the present instance, the tanks are approximately 34 'feet long, 12 /2 feet wide and 9 /2 feet in height. The particular dimensions are not critical and may be varied to a substantial extent without departing from the teaching of the invention. They are given here only in order to impart a better understanding of the invention.

The improvements which characterize the present invention are concerned with the novel arrangement of means for and manner of cooling the wort that is placed 'in the tank for fermentation. In this instance, the cooling of the tank is effected by circulation of a liquid coolant .in contact with the exterior surfaces of one or more of 'the metal walls of the tank as differentiated from the usual flow of a coolant through pipe lines or coils located within 'the tank in direct contact with the fermenting wort or been It is a principal object of this invention to provide a cooling system for tanks wherein direct contact is made between the exterior tank walls and a circulated liquid 'coolant by the passing of the coolant through channels or ducts formed directly on the exterior surfaces of the tank walls and which channels or ducts are of such crosssectional area and cooling surface that the temperature of the coolant can be higher than in conventional systems because of comparatively large volume flow at reduce linear velocity and pressure.

It is also a principal object of this invention to employ the wall stiffening channels or ribs of the tank as the passages through which the coolant is circulated so that channels or ribs serve a dual purpose, namely, as structural members and as coolant passages and thereby eliminate the coils which are normally provided on the interior of the tank.

It is a further object of this invention to so design and arrange or direct the coolant conducting channels that minimum friction between coolant and channel walls will be realized, thus providing lowest possible pressure loss; while at the same time the coolant will be caused to frequently change its direction of flow relative to the tank walls resulting in desirable and beneficial mixing within the coolant stream.

Yet another object of the invention is to provide a structure for cooling the liquid content of the tank that eliminates the possibility of the liquid coolant escaping or leaking into the fermenting wort; this result being effected by reason of locating the channels or ducts which contain the coolant exteriorly of the tank and by employing the metal walls of the tank as theinside wall forming part of the coolant ducts.

It is a further object of the invention to provide a cooling system for closed fermentation tanks that is so associated with the tank as to leave its interior entirely clear of any and all obstructions that would be detri- 2,988,334 Patented June 13, 1961 2' mental to easy washing or cleaning of the interior of the tank.

It is also an object of the invention to provide a tank cooling system in which any size batch or quantity of wort may be readily and effectively processed. I

In accomplishing the above mentioned and various other objects and advantages of the present invention, which will become apparent as this specification progresses, we have provided the improved details of tank construction, the preferred forms of which are illustrated in the accompanying drawings, wherein:

Fig. 1 is a side view of a fermentation tank embodying the various improvements of the present invention therein.

FIG. 2 is the lower end elevation of the tank.

FIG. 3 is an enlarged sectional detail, taken on line 3 3 in FIG. 1.

FIG. 4 is a horizontal sectional view of the tank, taken on the various levels of line 4-4 in FIG. 1.

FIG. 5 is an enlarged sectional detail, taken on line 55 in FIG. 1.

FIG. 6 is a horizontal section taken on line 6-6 in FIG. 1.

Referring more in detail to the drawings:

In FIG. 1, the present fermentation tank is designated in its entirety by reference numeral 10 and it is there shown as being supported for use on a floor surface 11 that has a downward slope whereby the right hand end of the tank is lowered below the level of its opposite end in order to facilitate the drainage of liquid from the tank.

The tank itself, as previously stated, is of substantial size and of rectangular form. both in cross-section and in longitudinal section, as is evident from its showing in FIGS. 1, 2 and 3. The tank is of welded sheet metal construction and its opposite sides, top, bottom and end walls are all joined in rounded corner bends, as has been illustrated quite clearly in FIGS. 3 and 5, at 12, this being to avoid hard to clean corners. For later explanatory and dmcriptive purposes, the opposite sidewalls of the tank are herein designated, respectively, by numerals 13 and 13; the top wall is designated by numeral 14; the bottom wall is designated by numeral 15; the rear end Wall, which is shown at the left hand side in FIG. 1, is designated by numeral 16 and the front end wall is designated by numeral 17. All walls are of sheet steel, which may be stainless steel or the inner surfaces of the walls may be lined or overlaid with an inert material, such as epoxy resins, glass or the like. it is normally less expensive to build a tank of mild steel and to line its interior surface with a suitable inert material.

It will be understood that the present. tank, as so constructed, is entirely free of any internal obstructions, breaks or roughness and with all corners rounded so that internal cleaning, washing and drainage can be readily accomplished. Draining of the tank is greatly facilitated by the previously mentioned sloping illustrated in FIG. 1 wherein the dash line 11x represents a horizontal plane and 11 is the downwardly sloping floor line. Also, the bottom wall of the tank is slightly troughed as illustrated best in FIG. 2, so that the contained liquid of thetank will drain to a longitudinal center line and thento the lower end of the bottom wall.

Although the bottom wall 15 is sloping as described, we desire to maintain the top wall 14 horizontal. This feature provides that the height or distance between the contents of the tank and the top isthe same throughout the length of the tank. Therefore, during fermentation, the foam space is of constant height above the liquid level. Another advantage of the horizontal top is that it reduces the required height of the rear end wall 16 of the tank which results in a saving of material and cost.

For filling the tank with the wort to be fermented, it

is equipped at its lower end with a filling pipe 20 which is shown in FIG. 1 to be horizontally disposed and to have an upwardly turned inner end portion opening into the tank through its bottom wall at the lowest point. This filling pipe 20 also serves as a discharge pipe in emptying or drawing liquid from the tank. The wort to be fermented is pumped into the tank and as the filling of the tank takes place, air is vented therefrom through a pipe 21 that leads from an opening in the top wall 14 at the forward end of the tank. The pipe 21 is also the means of withdrawing the CO gas which is formed by the formentation and for injection of compressed air after emptying of the liquid from the tank. The pipe is connected to an exhaust or discharge pipe, not shown, for carrying the gas to a point of discharge into space or for collection. The pipe 22 is a safety vent and connects with a water trap 23. The safety vent is to insure that too great a pressure will not be created in the tank in the event that the discharge of gas through pipe 21 becomes obstructed. It also is a safety vent against vacuum being created inthe tank as beer is withdrawn. The tank is normally filled with wort to approximately 80% of its capacity, that being to slightly more than three-fourths its depth, however, lesser quantities may be processed ii desired. The remaining 20% of the height of the tank provides space for the produced foam to collect. If the tank is used for storage, the tank may be filled completely.

The ability to process batches or quantities of any reasonable amount is one of the inherent advantages of our new and improved tank. It will be appreciated that the conventional internal coils are normally positioned near the maximum liquid level of a tank. This requires that the tank be filled to substantially the maximum liquid content for processing and proper cooling. :In our construction the channels extend substantially from the bottom to the top of the sidewalls so we are able to process any quantity that may be desired.

The cooling system, which is one of the features of the --present invention, employs the use of at least a portion of the stiffening or structural channels on the exterior surfaces of certain walls of the tank and the coolant is circulated through these channels. In the present instance, we employ only the channels on the opposite sidewalls for containing the flowing coolant. However, if desired or required, we mayvutilizethe channels on the top, bottom and end walls. In the present instance, it has been found that the cooling of the sidewalls is suflicient. The substantially U-shaped channels, as applied to the opposite sidewalls, are interconnected as shown in FIG. 1.

Each continuous channel is air tight and made up of a succession of spaced, vertical, hollow stiifening ribs 25 that are secured by welding directly to the exterior of the tank sidewalls. Each rib extends from near the bottom to near the top of the wall and in horizontal crosssection is of substantially quadrilateral form with opopsite sidewalls outwardly converging and so that the rib is wider across the base than at the outside, as is well shown in FIG. 6.

In FIG. 6, it is to be observed that the sidewall 13 of the tank forms the base wall of the channel; the opposite sidewalls of the channels are designated, respectively, by reference numerals 25a and 25b and the outside wall by numeral 25c.

Adjacent ribs are joined, alternately, near their lower and upper ends by horizontal channels 26 of cross-sectional form and area similar to the vertical ribs so that, from end to end, at each side of the tank the joined ribs provide a continuous channel or duct for the flow of a liquid coolant therein. The channels, as thus provided at opposite sides of the tank, are interconnected near the end Wall 16 of the tank for cross-flow through a hollow stiffening channel 30 that is applied transversely to the underside of the bottom of the tank. This channel being constructed similar to the vertical ribs on the 4 sidewalls. Connection of each of the opposite ends of this transverse channel with the lower ends of the opposite sidewall channels is as shown in FIG. 3 wherein it is observed that a pipe '35, formed as a right angle bend, is extended at its ends through the lower end wall 25d of channel 25 and the adjacent end wall 39a of channel 30 thus to provide for a flow of liquid coolant from one side of the tank to the other as indicated in the view by the arrows in the pipe. These connecting pipes at opposite ends of channel 30 are designated in FIG. 4 by numerals and 35'; each being like that shown in FIG. 3.

A removable pipe plug 35a is provided which is applied to the nipple 35b projecting from the pipe 35. This entrance into the coolant channel provides means for ascertaining the temperature of the coolant by insertion of a temperature sensing device at this point.

To permit the venting of air from the channels as they are filled with the coolant, the ribs 25 are each tapped and plugged at their upper ends as at 36 in FIG. 5. After a substantial quantity of liquidhas been pumped into the channels, normally to a point above the upper horizontal ribs, successive plugs are removed to permit the escapement of entrapped air. Additional liquid is added and venting repeated until substantially all of the air is removed from the system. During operation, the plugs may be removed momentarily to remove any air which may have entered the system.

-It has been shown in the several views that the end, top and bottom walls of the tank are equipped exteriorly with stiffening and strengthening channels or ribs of a form of construction similar to those applied to the side walls, but, as was previously stated, these serve in the present instance for stiffening only and not as coolant channels. The top wall stiffening ribs are designated by numerals 37 and those on the opposite end walls by numerals 37 and 37". Also, it is shown in FIG. 1 that stifi'ening webs 38 are applied at the lower horizontal corners to tie the ribs 37', 37 to the bottom wall 15.

It is further to be observed, in FIG. 2, that the end wall 17 is provided centrally, near its lower edge, with a manhole 40 equipped with door 41. Entrance to the interior of the tank for cleaning, repair or inspection may be made through this door. The unobstructed interior of the tank is quite advantageous for use of mechanized cleaners. It also provides maximum assurance that the tank can be completely and properly cleaned as is absolutely necessary in use of such tanks for fermentation of the wort into beer or for the storage of beer.

In the use of the tank, the wort to be fermented is pumped into the tank through pipe 20 to a desired level and the maintaining of the wort at the proper temperature during its fermenting period is effected by circulating the selected liquid coolant through the channels provided on opposite sidewalls of the tank. Circulation is effected by a pump, not shown, having discharge and intake connections respectively, with the intake and discharge pipes 42 and 43 that are joined with the channels at the front end thereof. As the tank is filled with wort or beer, air or gas is exhausted therefrom through the pipe vent 22.

Another detail of construction which provides definite advantages is the positioning of the horizontal channels 26 above and below, respectively, the lower and upper ends of the vertical ribs 25. Any solid impurities which might enter the coolant system can collect in the lower ends of the vertical ribs, below the lower horizontal channels without obstructing the flow of the coolant. Any gases or air which might be in the system can collect in the upper ends of the vertical ribs above the upper horizontal channels. Normally the upper horizontal channels are at liquid level so that most etficient cooling is assured.

In this operation, we prefer to use an aqueous propylene glycol solution as the coolant liquid, because it does not contain impurities which may settle in or block the channels or pump, nor is it required that the channels be frequently cleaned. However, other types of coolant may be employed if desired.

The cross-sectional area of the channels with their large cooling surfaces permit circulation of the coolant at a comparatively low linear velocity and there is repeated change in the direction of flow which is desirable in controlling the fermentation of wort in that it provides a continnous stirring or mixing of the coolant in the channel and thereby maintains a substantially uniform temperature of the coolant. The large cross-section also permits high volume flow at low pressure when desired for maximum cooling effect.

Also, the use of relatively large channels provides greater structural strength for the tank. Further, the large channels minimize pressure buildup in the coolant system. An increase in pressure could be destructive to the tank and it would increase the cost of maintaining the required circulation. It would require internal coils of substantially greater than conventional diameter to accommodate the flow of the same volume of coolant at the same pressure.

As a detail of construction, stifiening and strengthening bars 62 are applied vertically to the sidewalls of the tank to span the cut-outs in the sidewalls of the vertical ribs where the horizontal ribs are connected. The location of these bars is as shown in FIGS. 5 and 6. The semicylindrically rounded surfaces of these bars 62 aid in causing a smooth flow and in creating the mixing of the coolant as it flows thereacross. However, their main purpose is to give strength to the structure at those particular places.

It is desirable that the entire tank and coolant system are encased in a housing, preferably a shell of aluminum foil lined with insulation, such as fiber glass. Such an enclosing casing is designated by reference numeral 50 in FIGS. 1 and 4, wherein it is indicated in dash lines, and also in FIGS. 3 and 5 where it is shown in full lines and in section.

The insulating cover minimizes heat loss or any effect on the system from external heat sources. It also reduces exchange of effect between adjacent tanks and provides a better overall temperature control. Also, the cover increases the effective cooling area on the walls of the tank because in eflect it increases the cooling surface to include the portions of the tank walls between the ribs. The result -is that substantially the entire sidewalls are cooled thus making for greater efliciency.

As previously mentioned, the temperature of the coolant which we employ in our system may be maintained at a substantially higher level than the temperature of the coolant in a conventional system or structure wherein the coolant ducts or coils are positioned within the tank. In a conventional internal coil system of lesser cooling surface, the temperature of the coolant is normally within the range of 10 to 20 F. In our system, we can obtain the desired results with the temperature of the coolant maintained between 30 and 32 F., however, higher or lower temperatures may also be used. The higher temperature reduces cold shocks to the yeast and fermenting wort. The cold shocks are the sudden reductions in temperatures which may occur and which are detrimental to the action of the yeast. An internal coil accomplishing the same result would be large and cumbersome, expensive and lacking the many advantages described earlier.

To summarize; the present invention provides a less expensive tank construction by eliminating the cost of internal cooling coils, more uniform temperature control during fermentation, the ability to process quantities less than the full capacity of the tank, greater adaptability to mechanized cleaning of the tank interior, a completely smooth interior surface with no attachments or protrusions, no coils on the interior of the tank to obstruct cleaning, reduced linear velocity of the flow of coolant, with accompanying small pressure drop, avoidance of sharp temperature changes during fermentation, and rapid cooling of the tank contents at full coolant flow.

Our invention is not to be interpreted as limited to any specific tank design but is to be understood to include all fermentation, storage and other tanks of any size and shape wherein wall stiffening members are employed and secured to the exterior surface to strengthen the tank construction and wherein the cooling or heating medium is circulated through the stiflening members to provide the required temperature control.

What we claim as new is:

1. A stationary heat exchange tank for use in processing substantial quantities of fluids, said tank comprising interconnected top and bottom walls, opposite side walls and opposite end walls, all walls being joined to adjacent walls in a fluid tight relationship, the interior surfaces of all walls being completely smooth and free of protuberances, a plurality of substantially U-shaped channels vertically disposed and secured in spaced relationship to the opposite sidewalls, with the free edges of said channels joined in fluid tight relationship with said sidewalls, said vertical channels extending substantially the full height of the sidewalls, a U-shaped channel extending horizontally between each of the adjacent vertical channels, alternate horizontal channels interconnecting the vertical channels below the upper ends thereof and the remaining horizontal channels interconnecting the vertical channels adjacent the lower ends thereof, said interconnected vertical and horizontal channels forming a continuous fluid channel, a supply connection for supplying fluid to said continuous channel at one end thereof, a discharge connection for discharging fluid from said continuous channel, said discharge connection being secured to a channel at the opposite end of the continuous channel.

2. A tank structure as in claim 1 including means interconnect-ing the vertical channels on the opposite sidewalls whereby the entire channel system is continuous.

3. A tank structure as in claim 2 wherein there is a single supply and a single discharge connection for the continuous channel.

4. A tank structure as in claim 1 wherein the horizontal channels adjacent the upper ends of the vertical channels are positioned substantially below the upper ends of said vertical channels whereby an air collection chamber is provided at the upper end of each vertical channel and means on the upper ends of each of said vertical channels for exhausting entrapped air therefrom.

5. A tank structure as in claim 1 including means for venting said tank.

6. A tank structure as in claim 1 including U-shaped channels on the opposite end walls and top and bottom walls.

7. A tank structure as in claim 1 wherein the bottom wall of the tank slopes between the opposite end walls and the top wall of the tank is horizontal.

8. A tank structure as in claim 1 wherein said bottom wall is in the form of a longitudinal trough and said bottom wall slopes longitudinally between the end walls.

Del Mar Feb. 22, 1955 Stover Sept. 24, 1957

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