DuPont Merck Pharmaceutical Company Uses Ultrasound
to Replace Chemical Solvents in Tank Cleaning
Chemical and pharmaceutical companies have typically used chemical solvents to clean tanks. These traditional techniques depend on dissolving or emulsifying contaminants in a solvent to provide the cleaning action. These methods use solvent rinsing or multiple solvent distillations to clean process tanks and reactors. Solvents used include methanol, ethanol, methylene chloride, and isopropanol, all of which emit volatile organic substances during both the cleaning and the subsequent incineration of the waste.
Companies now how have a more environmentally-friendly, energy-efficient option. They can use the power of sound to clean large industrial tanks. Through a cost-shared demonstration project sponsored by the U.S. Department of Energy's NICE3 (National Industrial Competitiveness through Energy, Environment, and Economics) Program, TELSONIC Ultrasonics adapted ultrasonic technology to generate bubbles in fluid-filled tanks, thus cleaning inner surfaces without solvents, emissions, or manual labor for the DuPont Pharmaceuticals Company.
The purpose of the NICE3 Program
is to champion technological advances that don't receive the encouragement and
visibility that they should because low energy prices offer little motivation
for innovation. This program works with the most waste- and energy-intensive
industries in the
This project yielded energy savings on the order of ~237.23M kJ (224.85M Btu) per 758-L (200-gal) tank and annual cost savings of ~USD 35,000 per tank.
Each tank system consists of a tube resonator that uses an integrated ultrasonic transducer and rod-shaped tubular ultrasonic resonator that enters the water-filled tank via a top opening. The transducer and resonator vibrate at 20,000 times/second, creating high- and low-pressure zones that form tiny bubbles. These bubbles grow to a specific diameter and then implode violently, providing an intense scrubbing action on the inner surfaces, agitator blades, and bottom valves. These bubbles are small enough to penetrate microscopic crevices, making the process superior to traditional methods. This method eliminates cleaning solvents and associated wastes and reduces energy and labor costs.
When comparing this method to a typical distillation cleaning for an average 758-L (200-gal) tank, savings on the order of 1.240M kJ (1.175M Btu) are realized. Additional savings of ~1.041M kJ (987K Btu) result from reduced methanol usage. For an average system, the annual savings are ~237.23M kJ (224.85M Btu).
When considering the savings, the reduced use of methanol and reduced downtime must be considered as this method is considerably less time consuming than the traditional solvent cleaning method. So the annual energy savings per 758-L (200-gal) tank system equate to ~USD 350,000 Given the cost of the cleaning system, it takes only eight cleaning cycles (~4 weeks) to pay for a 758-L (200-gal) tank system.
By eliminating the use of chemical solvents in the cleaning process, no volatile organic substances are emitted. The resulting need for waste disposal (via incineration) is also eliminated.
DuPont Merck Pharmaceutical Company
Chambers Works Process Research Facility
Angelo C. Piro