CASE HISTORY—MINIMIZATION
OF ONCE-THROUGH COOLING WATER
USE AND DISCHARGE FROM BATCH FERMENTOR COOLING
Henry C. Molise, Energy Engineer
The Upjohn Company
Kalamazoo, Michigan 49001
INTRODUCTION
The Upjohn Company Portage Road Plant synthesizes pharmaceutical products by fermentation
and chemical processes. The Plant also formulates and packages pharmaceutical products and is the
site of the company's corporate headquarters.
The Plant water distribution system is supplied by company owned wells. The largest use of water
at the Plant is noncontact cooling. Water is used in a series of multiple applications, where feasible,
before discharging. A water conservation study was initiated to: (1) reduce the volume of groundwater
used; (2) reduce future capital investment in new wells and water storage facilities; and (3) reduce
the volume of spent cooling water which must be discharged to local surface waters.
Forty to fifty percent of the well water supply is used for fermentor cooling. Thus, a major focus
for water conservation was a study of cooling water use in the Plant's 36 largest fermentors which
range in volume from 13,200 to 39,600 gallons (50,000 to 150,000 liters).
Antibiotics and steroids are produced in batch fermentation reactions which use once-through
well water for temperature control. There are five separate types of fermentors which vary in combination of volume and cooling design. Cooling designs can be classified as parallel banks of either:
(1) internally mounted helical coils (various coil pipe diameters are used); or (2) external half-pipe
jackets mounted on the outside wall of the vessel. About a dozen different fermentation products
are made in the various fermentors, each of which has a different batch viscosity. The fermentation
process uses cooling water for two separate operations.
Post-Sterilization Cooldown
Prior to inoculation with the desired microorganism, the fermentor contents are heated to approximately 250 F (121 C), and held at that temperature to achieve sterility. The batch is then cooled
as rapidly as is reasonably possible to the desired inoculation temperature for the particular product
batch. The target temperatures are in the range of 82 to 90 F (28 to 32 C). Historically, the cooldown
has been accomplished by opening the cooling water control value 100% in order to achieve a maximum possible constant flow of cooling water.
Temperature Maintenance During the Biological Reaction
Heat enters the batch from agitator power input, the fermentor air supply, and the biological
exotherm. A temperature sensor inside the fermentor controls the cooling water value in order to
maintain the optimum temperature for promotion of the biological reaction.
WATER CONSERVATION STUDY PROCEDURE
A mathematical model of fermentor heat transfer was developed in order to evaluate various
hypothetical changes in fermentor cooling. Considering the large number of products made in the
different types of fermentors, computer programs were written to facilitate the large number of calculations. Field data was gathered as a basis for the model calculations.
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