;Volatile organic compounds (VOCs) are largely consumed in the manufacturing process of semiconductor industry. These VOCs will make a great burden to living environment or air quality once they escape or are discharged from exhaust pipes into the atmosphere. This study reports results of engineering improvement on exhaust from a semiconductor factory using a dual-fluidized bed system with adsorbed/desorbed activated carbon. The system has the advantages of uniform bed temperature of activated carbon, high mass transfer, and fast heat transfer. During operation, the fluidized activated carbon beads contact VOCs molecules uniformly. The VOCs were adsorbed by activated carbon beads and desorbed through regeneration process. Consequently, in addition to reduce pollution, the system has a merit of recycling and reusing the activated carbon beads. The engineering improvement was originated from the expections of the studied factory, without influencing product manufacturing, on eliminating three problems encountered in temperature, air volume, and blockage of the previous exhaust treatment system. This study analyzed the implications and results from various data recored from engineering improvement processes and the resulted economic benefits through the comparison of the engineering work before and after. The newly added equipment boosts the heat recovery efficiency of the two heat exchangers in the system and eliminates the blockage problem of silicon dioxide crystal in the tower tank of the equipment. The operating power consumption of the whole system is reduced approximately from 135 kw per hour to 110 kw per hour. The average electricity bill is estimated to reduce by about NT$1,900 per day and will be saved by about NT$690,000 a year. In addition, the measured bulk density of activated carbon was significantly decreased to reach 62 g/100 ml, which was equivalent to the new carbon specification due to good desorption and regeneration processes. This will maintain high adsorption capacity of activated carbon and ensure the efficicacy of the overall system in removing VOCs for meeting regulation requirements.
