CHAPTER IV FRICK MEDIUM PRESSURE RAW WATER SYSTEM
CORNER TUBE TYPE
The arrangement of a typical installation of the Frick Medium Pressure Raw Water Freezing System is shown in the opposite illustration. The air used in this system for agitating purposes is thoroughly cleaned, cooled and dried before it reaches the ice cans. It is compressed by a suitable air compressor, the pressure used varying from 15 pounds to 30 pounds per square inch, depending on the condition of the water from which the ice is to be made and the brine temperature carried in the ice tank. The amount and kind of impurities contained in the water are also determining factors in the character of the agitation required.
The dehydrating equipment for cleaning, drying and chilling the air is the heart of any medium pressure system.
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The Dehydrators 37
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Dehydrating Set The Frick dehydrating set is the result of eight years of painstaking experience and tests, and it performs its func- tions thoroughly with a minimum amount of attention.
The completeness of the dehydrating set is shown in the above diagrammatic illustration. The air from the com- pressor passes through a special filter into the air cooler. In the air cooler the air passes in finely subdivided streams up through cold water (which is kept clean automatically) and passes out at the top of the cooler. The air then enters the bottom of the dehydrator shell and in similar condition passes up through cold brine which thoroughly chills and dehy- drates it. After leaving the dehydrator, the air passes through another special filter, which removes any remaining traces of salt or dust from it. The air filters are duplex so that one side can be cleaned while the other is in use. The small brine pump and mixing tank are provided for strength- ening the brine in the dehydrator shell. ‘This unit does not have as much moisture and dust to remove from the air as the first unit or air cooler, therefore the brine level rises very slowly and it is seldom necessary to strengthen the brine more than once each week. ‘The air cooler and dehydrator are each provided with spiral direct expansion cooling coils. The operation of this dehydrator is very simple. No expense has been spared to make it complete and efficient. When
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Detail of Framework and Air Piping
conditions warrant, a set of double pipe water fore-coolers can be added to the dehydrating set at a slight additional cost.
After this special treatment, the air is led through suit- able headers to the cans. The main air header is located centrally in the wooden framework of the tank, and from this main header, small headers arranged in grooves in the framework pass transversely between each row of cans. To these headers the fittings shown are attached in such manner that the air may pass freely through the rubber air tubes to the brass tubes in the cans. All air headers and laterals in the framework are made of galvanized pipe.
The framework of the freezing tank is so designed that the rubber air hose when not in use may be placed in the slot provided for this purpose. This feature, as illustrated above, affords an extremely simple and convenient method of dis- posing of the hose when the ice is ready for harvesting.
A detail of the tube in the corner of the can is shown above. The brass tube extends from the top to the bottom of the can. The lower end of the tube is filled with a solid brass rod about 4” long and the air leaves the tube at the V notch shown. A hard brass head is brazed to the top of the tube. This head is machined so that the air fitting makes a neat tapered fit in it. The tube is solidly floated into the corner of the can with solder at the time the can is made and js therefore practically integral with the can.
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Showing Connection to Corner Tube
Harvesting
The air is left on the cans until the ice is frozen solid, the fitting then disconnected and flipped into the pocket in the framework, and the ice harvested just as distilled water or opaque ice. Since the air tube is integral with the can, there is no time lost in handling air tubes and the tubes cannot be damaged.
In medium size and large plants, Frick Company recom- mends the use of multiple can hoists, dip tanks and can dumps—either two, three, four, or six cans may be handled at one time according to the size of the tanks. The improved can filling device at the dump is also recommended, and of course an electric hoist. After the ice is dumped, less than a minute is required to fill the cans. ‘The filled cans are then carried by the crane to their cells, lowered into the tank, and the air fitting inserted in the corner tube—a very simple and easy operation. The maximum amount is thus harvested with minimum labor.
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Core Pumping
Clear, merchantable ice is made with the Frick Medium Pressure System without pumping cores: when the water is good, since the agitation continues to the end. If the water contains salts which precipitate in the cores as carbonates, and no purifying treatment is applied it will of course be necessary to remove cores and refill same as in any freezing system. ‘The same apparatus is used for this as for the low ure system, and it is explained in detail under the low ire drop pipe system.
MEDIUM PRESSURE CENTRAL TUBE SYSTEM
In some localities a central tube suspended in the middle of the can is preferred to the tube in the corner construction for medium pressure air. To meet this preference Frick Company has developed the Frick Central Tube Medium Pressure System. This system is identical with the tube in the corner system in all respec cept the arrangement of the tube in the ice can and the air fitting for connecting to the tube in the can. In other words, the same dehydrating system is used, air is used at the same pressure, and the air is left on the ice cans until the blocks are frozen solid. This
Frick Medium Pressure Raw Water Ice 41
Thawing Needle
being the case, since the tubes freeze into the center of the ice blocks, they must be taken out. A special thawing needle is provided for this purpose.
The special thawing needle for removing the air tubes from the ice is shown above. Warm water from the am- monia condensers is used for this purpose and only a few moments are required to thaw the tubes loose.
Center Tube Support
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Inserting Thawing Needle in Tube
The illustration on opposite page shows the method used to support the brass central tube. The support bars are made of galvanized iron and are fastened to the central tubes as shown.
A special adjustable air fitting is used for making the connection to the air tube. The illustration on page 44shows clearly the construction of this fitting and the method of connection.
Harvesting
The usual method of harvesting the ice with this system is as follows: The air is left on the cans until the ice is frozen solid; the air fitting is disconnected from the central tube and flipped into the pocket provided in the framework; the cans are taken from the ice tank and carried by the crane to the
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dip tank; the cans are lowered into the dip tank, then raised partially and the air tubes removed by means of the thawing needle and placed in a suitable rack provided; the cans are then raised from the dip tank, placed in the can dump and the ice dumped; next, the cans are refilled while in the dump and the air tubes put in place; and then the filled cans are carried back to their tank cells, lowered into the tank, and the air fitting connected. The simplicity of the harvesting is readily seen.
Detail of Air Fitting
Several cans are harvested at the same time, according to the size of the plant, as explained before. The paragraph on page 41 regarding core pumping applies also to the central tube medium pressure system.
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Ice Storage—Raw Water Ice Plant
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