A Case for Thermal Deoiling

The Problem

A major Air Conditioning company needed an alternate technology for degreasing evaporator fins. They had, until recently, been deoiling metal parts in a conveyorized solvent based vapor degreasing line.

The degreasing technology being used over the years to clean these fins was inefficient and additionally costing millions of dollars a year for water, chemicals and the disposal. In aqueous and solvent based cleaning methods there are not only costs associated with purchasing chemicals, but also disposal costs, high operation and maintenance costs and risk management costs.

At the same time, the costs of compliance with rules and regulations governing industrial hygiene, safety and the environment was forcing the manufacturing to reevaluate cleaning methods. Epcon had an initial meeting and proposed a Thermal Cleaning technology –a thermal Deoiler.

The Process

Thermal Deoiling is a process that uses indirectly heated dry air to clean parts contaminated with oils or lubricants. No water, solvents or other chemicals are used. The basic thermal process is well known, having been used for many years in industrial operations that require clean, dry parts such as brazing, coating, soldering and plating.

The difference between an Industrial Oven and a Thermal Deoiler is that the deoiler burns the oil vapor in a Thermal Oxidizer to provide clean, dry heat for the deoiling chamber. In effect, the oil itself is helping to clean the parts while it is being oxidized to carbon dioxide and water. A supplemental burner in the Thermal Oxidizer provides the balance of the heat needed for complete destruction of the oil, while indirect heating avoids condensation of water or oil vapor in the deoiling chamber or on the parts.

The Solution

Epcon Industrial Systems was contracted by the manufacturer to design and construct a waterless and solventless deoiling system to replace the solvent line in time to meet the deadline. The new system was to be a one-on-one replacement for the existing cleaning line in terms of production rate, configuration and parts carriers.

The installation of air curtains and careful placement of the return air plenums prevents vaporized oil from escaping the entry and exit vestibules. A programmable logic controller (PLC) serves as the operator interface. The operator is able to monitor and make changes to temperatures, fan speeds, motor actuated damper positions and alarms.

In order to eliminate the vaporized oil and the associated volatile organic compounds,  a Thermal Oxidizer was added to the system. Operating at 1,500°F with a combustion chamber residence time of 1.0 second, vapor destruction removal efficiencies (DREs) of greater than 95% were demonstrated. Two stainless steel shell and tube heat exchangers were installed at the oxidizer’s exhaust. The primary exchanger heats ambient air, which supplies the heat to the deoiler chamber, and a secondary exchanger saves fuel by elevating the temperature of the exhausted oil vapor prior to its destruction in the combustion chamber. The combustion of the oil provides up to 1,000,000 Btu per hour of heat for the deoiler. No heat source other than the natural gas fired burner and the oil’s heat of combustion are needed for maintaining the required temperature for deoiling.

The Benefits

The operating cost of the system is now in thousands of dollars per year instead of millions of dollars per year.

There are several benefits of a Thermal Deoiler when compared to liquid deoiling. The transport, storage and handling of chemicals, as well as disposal are all eliminated. Industrial hygiene, safety and environmental issues are reduced to a minimum.

Quality products require quality cleaning. Thermal Deoiling has been shown to be a viable, money saving technology when compared to other cleaning methods. Deoiler, oxidizer and heat exchanger configurations can be designed for almost any size, production rate, VOC loading and operating temperature.