Reducing Energy and Water Use in Process Cooling

Cooling water is a critical component in the research and development, bulk manufacturing, and packaging of pharmaceuticals. For example, batch processing in multipurpose reactors requires water for chemical reactions to take place at high temperatures and for final products to crystallize at low temperatures.

Many operations that convert bulk substances into their final, usable form need process cooling. The most notable example is the creation of capsules, which requires precise control of the temperature of the molding process that forms the gelatin. Other operations that need process cooling include the sterilization of liquid pharmaceuticals and the wet granulation process of forming tablets.

Other applications that rely on cooling water include condenser cooling, vacuum systems and chambers, calorimeters, power supplies, heat exchangers, jacketed vessels, and plastic molding and extrusion equipment.

The current state of process cooling
Although cooling water is critically important in the processing of pharmaceutical end products, traditional process-cooling systems have big drawbacks. The systems entail significant costs because they require maintenance and consume a lot of energy, water, and chemicals.

Many pharmaceutical facilities contain large, energy-intensive cleanrooms. Traditional chillers can account for more than 50% of the energy use in cleanrooms because of the amount of cooling needed and the level of filtration that the US Food and Drug Administration requires (1). It is estimated that the pharmaceutical industry spends more than $1 billion on fuels and electricity today.

Despite concerns about energy use, the associated harm to the environment, and maintenance challenges, most pharmaceutical companies in the US have not replaced their traditional cooling towers and chillers. Manufacturers may not be aware that an alternative to these systems has been used in Europe for years and is becoming more common in the United States.

An advanced technology
The alternative technology is a closed-loop, dry-cooling system that prevents the water it contains from evaporating. The system also eliminates the need to dispose of the water after it has run through the process. The clean, often chemical-free, water is reused repeatedly for a plant’s heating or cooling needs, and the system reduces water, energy, and chemical consumption by 95%. This technology is appropriate for cleanrooms and other pharmaceutical processing needs. It can also help drugmakers conserve their manufacturing resources.

How it works. Traditional cooling towers do not achieve optimum performance at high ambient temperatures (e.g., 85° F). The new closed-loop technology maintains water temperature in hot weather by using an adiabatic chamber. Outside air passes through this chamber, and misters pulse water into the chamber. The humidified air lowers the water temperature to the desired point. The pulsed water evaporates instantly, cooling the air before it reaches the cooling coils that carry the process water. The coils remain dry, thus the process is called dry cooling.

Even in cold weather, a closed-loop, dry-cooling system does not accumulate ice because no water evaporates from the unit. Because it is not exposed to the elements, a closed-loop system does not face other maintenance issues (such as requiring water treatment) that are common to traditional towers. In addition, the system’s controls drain water from outside pipes to inside pipes when the air temperature reaches 32 °F. This feature keeps water from freezing and eliminates the need for glycol. A dry-cooling system also offers ample opportunities for free cooling, which occurs when outdoor temperatures drop below process temperatures.

Intelligent controls improve efficiency. The closed-loop technology incorporates an intelligent control platform that adjusts the system so that it runs at optimum efficiency, conserves resources, and enables the production of high-quality products. Depending on ambient temperature and process-water temperature, the controller adjusts the system’s fan speed, water pressure, and pump rotation to generate the required cooling capacity efficiently.

A pharmaceutical manufacturer that switches from traditional cooling systems to this technology can expect to reduce energy consumption by 60–95%, depending on the system it currently uses. The energy savings may provide a remarkable return on the company’s investment. The technology requires little maintenance and reduces companies’ water, energy, and chemical consumption. Dry-cooling systems can provide economic and environmental advantages that are particularly important to the drug industry today.

Reference
1. M. Neelis, E. Worrell, and E. Masanet, “Energy Efficiency Improvement and Cost Saving Opportunities for the Pharmaceutical Industry: An ENERGY STAR Guide for Energy and Plant Managers” (Ernest Orlando Lawrence Berkeley National Laboratory, June 2008).

Steve Petrakis is president of Frigel North America, 150 Prairie Lake Rd., Unit A, East Dundee, IL 60118, tel. 847.540.0160, s.petrakis@frigel.com.