Process Modeling and Exergy Analysis for a Typical VOC Thermal Conversion Plant

Abstract

The emission of volatile organic compounds (VOCs) represents a major source of air pollution and presents a major risk to both the surrounding environment and local health. An efficient and clean VOCs conversion process is an important approach for energy conservation and emission reduction. In this work, process simulation is conducted using Aspen Plus according to a VOC thermal oxidizing plant for an industrial-scale aluminum spraying production process. Experimental measurements are used for model validation and the pollutant emissions are consistent with the actual plant operating parameters, where the concentration of sulfur oxides is 32 mg/m³, and that of nitrogen oxides is ~34 mg/m³, both of which are below the requirements specified by the national environment regulations in China. Energy and exergy analyses have been conducted from the perspective of the second law of thermodynamics. It is found that 68.8% of the output energy in the system considered here enters the subsequent oven production line, which will be reused for drying the aluminum plates, and the rest of the energy will contribute to the water heat exchanger; however, the furnace features the largest exergy loss of 34%, and this is due to the high-temperature heat loss. The water heat exchanger features 11.5% exergy loss, which is the largest for the series of heat exchangers, and this loss is due to the large temperature difference between the hot and cold streams in the water heat exchanger. These findings are expected to provide practical approaches to energy conservation from the perspective of energy management.

Keywords

• VOCs
• thermal conversion
• process simulation
• exergy analysis