Distillation Column Design

EXECUTIVE SUMMARY:
The main objective of this project was to carry out a design on the Propane distillation column for a process that produces 1,3 Butadiene. The raw materials used are Butane, Oxygen and Water and the process capacity is 100 000 tonnes per annum nominal. In the previous work it was stated that the plant is located in China. The main location of the plant is in the capital city of the Gansu Provence, Lanzhou. This was decided as the location over other provinces due to the excellent transport links and the availability of raw materials and cheap labour. The close proximity to suppliers, customers and skilled labour all make Lanzhou the ideal location for the plant to be located.
The design of the distillation column consists of the packed type. The distillation is a multi-component distillation involving separation of Propane from the other components at very high pressure. The number of theoretical stages chosen was 16 stages based on a reflux ratio of 0.608. The column diameter calculated was 0.61 at maximum pressure gradient possible for distillation columns and 0.66m for minimum pressure gradient, which was then scaled up to 0.65m. This was a reasonable decision as it may be helpful when the plant capacity increases. The column has a height of 8m. Feed location for the arrangement of packing is at stage 3 from the top of the column. Pall rings constructed out of stainless steel with a size of 25mm is used for packing. The vessel thickness of the column is around 5mm, constructed out of stainless steel also to avoid corrosion.
A preliminary design on the condenser for this distillation column was also carried out. The type of condenser is a fixed plate with a 1 shell and 1 tube pass. The tubes are stainless steel, 119 in number, 2.44m in length, and with a square pitch arrangement. The overall heat transfer coefficient was also calculated as 486.026W/m2C. The pressure drop on the tube side was 7.306 N/m2 (almost negligible) as only one

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