important
role
in
producing
refined
products
MEMO: from Oliver Morfit Director o f Research and Production Malrnrfrom Chemical Corp.
1948, when we first started I laboratory work to determine the N
feasibility of dividing U.S.P. anhydrous lanolin into fractions, it became evident from the outset that the manner of chilling would play a very important role in the end results that were achieved. Our company produces a refined lanolin oil and other lanolin products, including a hard separation of lanolin having the consistency of beeswax. In the manufacture of our liquid lanolin, which is used in cosmetics, drugs, and pharmaceuticals, we start with a lanolin solid. Chilling techniques
In approaching this problem the laboratory tried a large number of solvents and various chilling techniques. All of the experiments showed quite clearly that the chilling rate would have to be very closely controlled and that the chilling differential could not be greater than 10" to 1.5" F. below the material being chilled; if the chilling differential was greater than this the chilled solution would not filter. Such control in the laboratory was fairly simple. It consisted of a container for the lanolin-solvent mix inserted into a chilling liquid to which dry ice was added from time to time as required to lower the temperature. Transferring this experimental data to commercial plant design was another story. I n addition to chilling, as described above, the lanolin-solvent mixture had to be heated to an elevated temperature prior to starting the chilling cycle, in order to ensure complete solubility of the lanolin in the solvent. I n order not to have separate chilling and heating systems, consideration had to be given to using the same system for both of these operations. December 1955
We finally decided to use two tanks, each containing calcium chloride brine solution with a freezing point of a t least 50" F. One tank would always be hot, with temperature regulation by instrument. This controller would maintain the desired temperature by throttling the flow of low pressure steam to the inlet of a steam coil within the vessel. The other brine tank, on the other hand, would always be maintained a t a low temperature obtained by a Freon refrigeration system. Heating-chilling cycle
At the start of a heating-chilling cycle, the brine from the warm tank is used for heating the lanolin-solvent mixture in the crystallizing vessel. Heating as well as chilling is accomplished by means of circular finned coils located inside the crystallizing vessel. After heating to obtain complete solution, the process of chilling
of the lanolin-solvent mixture is started. Chilling is done by mixing warm brine from the warm tank with cold brine from the Freon-refrigerated tank. The mixing of these brines is governed by a recording temperature controller which adjusts air-operated control valves to mix the brine in the proper proportions, so that the brine temperature in the tank is no more than 15" F. below the material that is being chilled. The rate of chilling is controlled by an instrument whose control point is continuously and automatically adjusted by a cam according to a predetermined schedule of time and process conditions. The cam can be cut to give any chilling rate that is desired within the limits of the refrigeration system. After the mixture of brines has passed through the coils in the crystallizer vessel, the brine is split, by means of a three-way control valve, and re-
Control valves regulating mixture of hot and cold brine
INDUSTRIAL AND E N G I N E E R I N G CHEMISTRY
f- For further information, circle number 92 A on Readers' Service Card, page 111 A
93 A
Plant Engineering Memos turned to the warm and cold brine tanks in the same quantity as was originally removed. I n this manner, the brine quantity in each tank remains constant. The brine from each tank is pumped, before mixing, by means of centrifugal pumps each having a capacity of 50 gallons per minute. These pumps run continuously during the chilling cycle, even if the control instrument calls for all cold or all hot brine. At the start of the chilling cycle, the operation may call for a mixture of 80% hot and 20% cold brine. At the end of the cycle, the requirements of the process may call for 100% cold brine. Temperature controller instaIIed
of Knighf-Consf r ucfed Pipe, duct and fittings
CHEMICAL EQUIPMENT From piping to complete plant, K n i g h t can supply you with corrosion proof chemical equipment engineered and constructed to your specific requirements.
Towers, absorbers, scrubbers
In each case, o u r engineering department first checks function and service conditions in order to select the most suitable materials. These may include K n i g h t developed materials such as Knight-Ware, Permanite, Pyroflex, Sealon, or any others which are best suited to the particular job. T h u s each u n i t is custom engineered t o give lasting service under toughest corrosive conditions. T o make the package complete, K n i g h t also supplies tower packings from the widest selection available, as well as special corrosion-proof cements and coatings.
Separators, reactors, kettles, surge tanks
See us in Space No. 7 a t the Philadelphia Chemical Show.
For further information on Knight products and materials send for illustrated bulletin No. 1 1 -U, Knight Chemical Equipment.
auric= A- Knish+
9912 Kelly Ave., Akron 6, Ohio
When we started actual operation a t the Malmstrom Chemical plant, it was found that both the hot and cold brine tanks would vary greatly in temperature, because in returning the brine to the tanks relatively hot brine would be added to the cold tank and cold brine to the hot tank. A temperature controller was installed in the hot brine tank to maintain a constant temperature; only the cold tank now varies. This variation in itself is not very great-from -15" to + l o " F., depending on the operation being performed. I n this manner, it was possible to control the rate of chilling by means of the time-temperature cam governing the mixture and flow of brine to the crystallizer vessel. At the same time, the temperature of the brine is never lower than 15" F. below the temperature of the mixture in the crystallizer vessel. I n actual practice, the chilling differential a t the start of the cycle is about 4" F. and a t the lower temperatures it is about 10" F., the change being due to the increased viscosity of the solution a t reduced temperatures. Duplication of results from batch to batch is simple if the same chilling curve is duplicated. Charging the chilling rate or final chilling temperature means only cutting another cam to fit the control instrument. I n case of instrument or air failure, the chilling system is valved, so the process can be carried out by manual operation. Newark, N. J. November 1 , 1955
94 A
I N D U S T R I A L A N D E N G I N E E R I N GC H E M I S T R Y
Vol. 47, No. 12
For further information, circle number 95 A on Readers' Service Card, page 111 A+
