Emission Control and Elimination Through The Use Of Condensation and Heat Recovery Technologies- A Case Study

Abstract

Existing regulatory air requirements have created potential restrictions on current and future plant operations. Any process design that allows for the elimination of discharge points and the reduction of emissions at a major source can affect the strategic planning for the facility. This can provide critical flexibility, especially in fast-paced markets. Such a process design and implementation were undertaken at a ceramic capacitor manufacturing facility. This facility utilizes multiple small-scale solvent drying processes that emit volatile organic compounds (VOC's). These exhausts could be recirculated for the purposes of emission point elimination, heat recovery and solvent reuse. The aim was to create an environmental control process which would pay for itself within two to three years. An assessment of the alternatives was completed and standard HVAC-type condensation was selected. The unit operations for the proposed process consisted of a high efficiency air-to-air heat exchanger, cooling coil and a chiller. The air passing across the heat exchanger and coil would begin to dehumidify. In addition, solvents contained in the air stream would begin to condense to some equilibrium level and would be absorbed in the condensing water. Eventually, since there would be no addition of water in the process, the level of water in the condensate would fall off dramatically. A prototype unit capable of handling three ovens with a total air flow of 1200 ft3/min (cfm) was installed. The unit performed as expected with the exception that condensate concentrations remained low. Product testing was undertaken to ensure that returning air containing a low level of solvent would not adversely affect drying operations or product qualities. No adverse effects were found. Monitoring of the air stream verified solvent levels well below 5% of the lower explosive limit. Finally, a large-scale unit was constructed capable of handling up to 171 ovens at up to 68,000 cfm at a cost of $1.2M. At current levels of integration, cost avoidance (savings) performance is within 2% of predicted values. Projected payback is 18 months. Estimated volatile organic compound emission reduction is 100 tons per year.