Cleaner production and reduction of ozone depleting substances in industry

Location:

St. Louis, Missouri, United States of America.

Problem Overview:

Use of ozone depleting substances in industry

As stipulated in the Montreal Protocol, the use of ozone depleting substances (ODS), including refrigerants, coolants, and degreasers, must be phased out and eventually eliminated from industries governed by signatories of the treaty. Many industries, however, are under pressure and continue to struggle with cost efficient mechanisms to convert to environmentally sound technologies and cleaner production systems which do not employ ODS.

Background:

Emerson Electric Co. is among the largest industrial corporations in the world, employing 73,000 people and maintaining 270 manufacturing sites. For over a century, the company has manufactured products including appliance components; heating, ventilation, and air-conditioning components; fractional horsepower motors; and industrial motors and drives. Exporting to nearly 180 countries, the company’s worldwide sales have been estimated at US$8.6 billion in 1994.

In 1992, a team of engineers evaluated alternatives for replacing the existing TCA degreasing equipment with the aqueous and ultrasonic cleaning systems. First, the team evaluated various cleaning systems used at other facilities and, based on information they had received about aqueous cleaning equipment, chose a spray wash and other ultrasonic systems as a feasible replacement. The implementation process involved two phases. The first included the replacement of the vapor degreaser with a Branson/Delta Sonics 4-stage ultrasonic cleaning system and a spray-immersion washer. In 1993, the parts were customized to the plant and installed. The second phase involved the replacement of vapor degreasers with spray cabinets. The two step wash system includes a spray wash stage and a forced air drying stage.

Initially, the parts go through the ultrasonic agitation which induces pressure changes. As bubbles form and implode, the parts are scrubbed and cleaned. Once the washing process is complete, the parts are transferred to the rinse stage where high powered jets spray water to remove the remaining cleaner. Finally, the parts are then transferred to a hot air drying unit. This new system cleans 1 basket of parts every 2.5 minutes, or 24 baskets per hour. While more baskets were cleaned per hour with the solvent system, many parts were run through the solvent degreaser more than one time due to inefficiencies in the system.

The total cost of the entire replacement amounted to US$280,000. While the initial costs were significant, the new cleaning system affords greater cost-efficiency and reduces total solvent consumption by 710 tons. The total annual savings from the conversion were US$80,000 in 1993; US$150,000 in 1994 and US$187,000 in 1995.

In total, the implementation of the cleaning system reduced facility emissions by 69% in 1988-1993; and, in 1994 all TCA use was eliminated in its operations, while quality has of the products has stayed constant.

It is feasible to apply the cleaning operations discussed above to both developing and developed countries. Aqueous and ultrasonic cleaning processes are less expensive and more efficient than ODS solvents, such as TCA, and thus should be considered for installation in developing countries. It is important, however, that care be taken in deciding the appropriate system for each plant since conditions may vary.

Status:

An evaluation of the project concluded that the replacement of the TCA solvent degreasing system both reduced the cost of cleaning the parts and reduced the use of volatile chemicals which are harmful to the environment.

Submitted by:

Clare Parker
United Nations Environment Programme
2 UN Plaza, Rm. DC2-803
New York, NY, 10017
USA

Contact:

Emerson Electric Company
Harold Lamboley
Vice President
Tel: (314) 553-1365
Fax: (314) 553-1007
8000 W. Florissant
PO Box 4100
St. Louis, MO 63136-8506
USA

Information Date: 1997-01-01
Information Source: Identifying Alternative Solvents to Protect the Ozone Layer: Case Studies from Around the World, UNEP