Structured packing in air distillation

An economic analysis has been performed to establish when it is advantageous to use structured packing in air separation plant. A model of a low pressure cycle was developed to calculate the power saved when packing is used, and cost models were developed for the columns and cold box. The rate of return was calculated on the extra investment required for a packed plant based on the annual power saving. Structured packing was found to be economic only in larger plants, where economies of scale mean that the increased capital cost becomes less significant compared with the power saved. It was also found that different sized plants favour different packings. The analysis identified that the packing variable with the biggest impact on the economic balance was the efficiency and that increasing the efficiency of current packings could enhance their balance in air distillation. A new packing was therefore developed to have a higher efficiency than conventional ones. The vapour phase resistance was targeted for reduction, since most packing models predict this to be dominant. The final shape was chosen as the easiest and most economic to make. It has converging and diverging channels and was manufactured in two specific areas and with two block heights by Tianjin University Packing Factory. A 0.3 m diameter distillation column test rig was designed, built and commissioned with the standard Sulzer Mellapak 500YW. It was then used to test the new packing alongside some standard ones. Because the packings had different specific areas, correlations of published results were developed to allow a true comparison to be made. The test results show that, unexpectedly, the packings with 0.1 m high blocks have an efficiency about 8% greater than the standard 0.2 m blocks. The new shape as implemented in the 350Y packing shows an additional 7% greater efficiency, so it is 15% better than a standard packing with the same area. It has a better efficiency than the Mellapak 500YW and the higher capacity associated with its lower area. The new 500Y did not show a significant advantage.

Optimal packing for cascaded regenerative transmission based on phase sensitive amplifiers

We investigate the transmission performance of advanced modulation formats in nonlinear regenerative channels based on cascaded phase sensitive amplifiers. We identify the impact of amplitude and phase noise dynamics along the transmission line and show that after a cascade of regenerators, densely packed single ring PSK constellations outperform multi-ring constellations. The results of this study will greatly simplify the design of future nonlinear regenerative channels for ultra-high capacity transmission

Optimal packing for cascaded regenerative transmission based on phase sensitive amplifiers

We investigate the transmission performance of advanced modulation formats in nonlinear regenerative channels based on cascaded phase sensitive amplifiers. We identify the impact of amplitude and phase noise dynamics along the transmission line and show that after a cascade of regenerators, densely packed single ring PSK constellations outperform multi-ring constellations. The results of this study will greatly simplify the design of future nonlinear regenerative channels for ultra-high capacity transmission. © 2013 Optical Society of America.

Efficient packing for phase regenerative channels

We compare the performance of advanced modulation formats in cascaded phase regenerative systems and demonstrate the importance of constellation optimization to the transfer function characteristics of the regenerator. © 2013 IEEE.