Thermal Deoiler Replaces Liquid Degreasing Line for Large Air Conditioning Manufacturer
Project No 1534
The Challenge
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.
In aqueous cleaning and solvent based cleaning there were several million dollar operating costs associated with purchasing and disposing of chemicals, high operating cost and wastewater fees, maintenance and risk management costs.
At the same time, the state environmental agency mandated that the line be shut down on a certain date due to the excessive water and air pollution it generated . With the regulatory compliance deadline rapidly approaching, Epcon was contracted by the manufacturer to design and construct a waterless and solventless deoiling system to replace the solvent line in time to keep its doors open. 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 Solution
Epcon proposed Thermal Clean technology – a thermal deoiler. 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 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 natural gas fired 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.
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 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, allowing them to monitor and make changes to temperatures, fan speeds, motor actuated damper positions and alarms, while keeping running records of the data, which can be charted in graph form at any time.
The Results
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 operating cost of the system is now in thousands of dollars per year instead of millions! There are several benefits of a Thermal Deoiler when compared to liquid deoiling. The transport, storage and handling of chemicals are eliminated. Industrial hygiene, safety and environmental issues are reduced to a minimum. Fugitive emissions are eliminated and air pollution is reduced to a minimum. Waste treatment and disposal are eliminated. Maintenance and operating costs are reduced. There is no contact of the parts with the products of combustion – they exit the deoiler clean and dry.
The reduction of intangibles such as safety and industrial hygiene management costs is unknown, but probably significant. 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 part size, production rate, VOC loading and operating temperature.