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Novel off-Gas Treatment Technology To Remove Volatile Organic Compounds with High Concentration

Sui, Hong, Zhang, Tao, Cui, Jixing, Li, Xiqing, Crittenden, John, Li, Xingang, He, Lin
Industrial & Engineering Chemistry Research 2016 v.55 no.9 pp. 2594-2603
absorbents, absorption, energy, equipment, gases, heat treatment, laboratory experimentation, liquids, operating costs, pollution, solvents, sustainable technology, temperature, triethylene glycol, volatile organic compounds
The triethylene glycol (TEG) was used to treat the off-gas stream containing 16 volatile organic compounds (VOCs) with high concentration (up to 15000 ppm) by experimental solvent absorption and ASPEN Plus computational simulation, respectively. This solvent absorption technology (SAT) not only purifies the off-gas but also recovers the VOCs. The effects of some typical operational parameters, including temperature, pressure, liquid loading rate, ratio of absorption liquid to gas flow rates, and absorption column height, on the absorption efficiency have been systematically investigated. Simulation results show that the optimal operational conditions are determined as 30 °C, 0.5 MPa (absolute), recycling TEG (with a purity of 99.9%) to a gas ratio of 4:1 by weight, and 8 theoretical stages. In addition, two stages of thermal coupling are applied minimizing the energy consumption of the off-gas absorption process, leading to a reduction of 89.77% in energy consumption. Laboratory experiments and field tests show that both VOCs absorption efficiency (using TEG as absorbent) and regeneration efficiency are highly consistent with those of ASPEN Plus simulation, suggesting the feasibility of simulation. Based on pilot-scale tests, the equipment investment and operational costs of SAT have been calculated and analyzed. Results show that the SAT is comparable with the traditional thermal treatment but with the advantages of much less secondary pollution. These findings indicate that the solvent absorption method is a promising green technology for treating high VOCs off-gas.