Simulation and Optimization of Distillation Processes for Separating the Methanol–Chlorobenzene Mixture with Separate Heat-Pump Distillation

The methanol–chlorobenzene mixture has a larger relative volatility in the low composition range than in the high composition range. Based on this characteristic, the mixture can be effectively separated by separate heat-pump distillation (SHPD) with significant energy savings. The binary interaction parameters of the UNIQUAC equation were used to predict the vapor–liquid equilibrium by means of the binary interaction parameters included in the Aspen Plus database. To minimize the overall annual operating costs, simulations for SHPD were carried out using Aspen Plus software, including the RadFrac and Compr blocks, and the optimal operating conditions, such as the split-point concentration, were determined. Simulations for conventional distillation, conventional heat-pump distillation, and multieffect distillation processes were also carried out for comparison. The simulated results showed that the SHPD process has obvious advantages over the other distillation processes in the assessment of energy savings and overall economic efficiency

Particle- and gas-phase PAHs toxicity equivalency quantity emitted by a non-road diesel engine with non-thermal plasma technology

Polycyclic aromatic hydrocarbon (PAH) toxicity equivalency quantity (TEQ, denoted by benzo(a)pyrene equivalent (BaPeq) concentration) is more meaningful when evaluating the influence of non-road diesel engines PAH toxicity on environment. Particle- and gas-phase PAH BaPeq concentrations were calculated based on gas chromatography-mass spectrometer (GC-MS) results and toxic equivalency factors. A non-thermal plasma (NTP) reactor was applied to a non-road diesel engine to decrease PAH TEQ content. Only the gas-phase Nap BaPeq concentration increased slightly with the action of NTP at three different generator power outputs. BaP dominated the BaPeq concentration for 15 samples with, and without NTP except in the gas-phase at 4 kW. Almost all medium molecular weight (MMW) and high molecular weight (HMW) PAH TEQs increased for particle- and gas-phases at 3 kW power output compared to 2 kW without the use of NTP. Particle-phase Nap, Acp, and AcPy (low molecular weight, LMW) TEQ were under detection at 3 and 4 kW, while gas-phase BkF, IND, DBA, and BghiP (HMW) concentrations were below the limits of detection. The most abundant PAH TEQ compounds were MMW and HMW PAHs for gas- and particle-phase while they were BaA, CHR, BbF, BaP, and IND for PM aggregation. The total BaPeq emission factors were 15.1, 141.4, and 46.5 μg m−3 at three engine loads, respectively. Significant BaPeq concentration percentage reduction was obtained (more than 80 and 60 %) with the use of NTP for particle- and gas-phases. A high TEQ content was observed for PM aggregation (38.8, 98.4, and 50.0 μg kg−1) which may have caused secondary PAH toxicity emissions. With the action of NTP, the breakup of MMW and HMW into LMW PAHs led to reduction of some PAH concentrations