TABLE OF CONTENTS The design exercises given in this appendix are somewhat more structured than those given in Appendix E. They have been adapted from design projects set by the Institution of Chemical Engineers as the final part of the Institution's qualifying examinations for professional chemical engineers.
Design a plant to produce 40,000 metric tons (tonnes)/year of 2-ethylhexanol from propylene and synthesis gas, assuming an operating period of 8,000 hours on stream.
The first stage of the process is a hydroformylation (oxo) reaction from which the main product is n-butyraldehyde. The feeds to this reactor are synthesis gas (CO/H 2 mixture) and propylene in the molar ratio 2/1, and the recycled products of isobutyraldehyde cracking. The reactor operates at 130 C and 350 bar, using cobalt carbonyl as catalyst in solution. The main reaction products are n- and isobutyraldehyde in the ratio of 4:1, the former being the required product for subsequent conversion to 2-ethylhexanol. In addition, 3% of the propylene feed is converted to propane while some does not react.
Within the reactor, however, 6% of the n-butyraldehyde product is reduced to n-butanol, 4% of the isobutyraldehyde product is reduced to isobutanol, and other reactions occur to a small extent yielding high molecular weight compounds (heavy ends) to the extent of 1% by weight of the butyraldehyde/butanol mixture at the reactor exit.
The reactor is followed by a gas-liquid separator operating at 30 bar from which the liquid phase is heated...
