created, maintained, and continually renewed to maximise utilisation of the packing surface. Performance of the distilla- tion column is enhanced as the useful capacity is extended. The latest generation structured packing MellapakEvo embodies these features and outperforms the current benchmark MellapakPlus packing in both efficiency and capacity (see Figure 2 ). Tested and proven in Sulzer’s in-house R&D facility in Oberwinterthur, Switzerland, and in an independent testing facility located in the US, the new packing offers up to 40% higher separation efficiency at the same useful capacity and pressure drop than MellapakPlus 252.Y. Compared to MellapakPlus 452.Y, it offers simi- lar separation efficiency with approximately 20% higher capacity (see Figure 3) . The superior mass transfer and hydraulics performance of the latest generation of structured packing benefits distilla - tion columns in several ways. Typically, the diameter and height of a separation column are determined by the required separation stages (effi - ciency) and energy (reboiler duty). The reflux ratio of the column can be reduced with a higher number of theoreti- cal stages supplied in a column. Provided that the overall pressure drop is maintained, the same product quality can be achieved with lower reboiler duty.3 An optimised col - umn design will balance the trade-off between the capital cost associated with a taller column due to greater packed bed height and the operating cost of energy to supply the required heat to the reboiler. MellapakEvo benefits the col - umn design by increasing the number of separation stages without the penalty of introducing taller columns, which incur higher capital costs. With increasing energy costs, the economic benefits of installing higher efficiency in the col - umn would be substantial. In the chemical and petrochemical industries, distillation columns are expected to operate for decades. A lifespan of 20-30 years is not uncommon. While it is costly to replace the entire columns, it is relatively easier and less expensive to upgrade the column internals for process improvement during the lifespan of a column. With careful analysis of the existing column configuration, the latest generation of packings and internals can be installed to provide higher
Commercial 19%
Residential 21%
Transportation 28%
Industrial 32%
45–55% Energy consumed by separation process
49% Distillation
The rest Other separation processes (thermal and non-thermal )
Figure 1 Breakdown of energy consumption in the US
petrochemical industry was the largest industrial energy consumer in 2021. In the US, about half of the energy con- sumed in the industrial sector comes from both thermal and non-thermal separation processes. Distillation alone accounts for 49% of the energy consumed by separation processes (see Figure 1 ).2 It becomes evident that crucial effort needs to be made to improve the eco-efficiency of distillation processes. Energy-efficient design can be achieved through process design and/or equipment design. The most straightforward approach is to increase the separation efficiency in the dis - tillation column by introducing a high-performance mass transfer component without compromising the hydraulic performance (capacity). An advanced structured packing is characterised by a highly effective interfacial or wetted area promoting the mass transfer between the vapour and liquid phase to sep- arate components in a distillation column. At the same time, the pressure drop is kept to a minimum due to the packing’s low resistance to the gas flow, thereby extending the use - ful capacity of the packing. Wettability on the packing sur- face has a remarkable effect on efficiency. Superior surface texture ensures that the liquid film on the wetted surface is
220
750.Y
Mellapak MellapakPlus
200
752.Y
602.Y
180
160
500.Y
MellapakEvo
350.Y
452.Y
140
352.Y
120
100
250.Y
M2.Y
252.Y
202.Y
80
170.Y
60
50
60
70
80
90 100
110
120 130 140
150
160
Capacity increase (%)
Figure 2 A view on the surface of MellapakEvo structured packing
Figure 3 Sulzer MellapakEvo performance for vacuum operations
50
PTQ Q3 2024
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