Retsam Fut - Academia.edu (original) (raw)

Books by Retsam Fut

An absorption column is required to recover acrylic and acetic acid from the gaseous reactor effl... more An absorption column is required to recover acrylic and acetic acid from the gaseous reactor effluent by contacting gas with water. Two incoming streams are handled by the column. The first is the gas stream of 5756,14 kmol/h with 0,078 % (wt./wt.) acrylic acid. It enters at a temperature of 280,50 °C and a pressure of 1,79 bar. The second stream contains processed water available from plant available at 30 °C and 1 bar and it is mixed with 500 ppm of hydroquinone inhibitor. The choice of hydroquinone as an inhibitor for this process was facilitated by its known properties to prevent polymerization of acrylic acid that is susceptible to radical-initiated polymerization (Schork, 2006). The preferred inhibitor dilution range is between 300ppm – 700 ppm (Elder J.E, 2006). The column has two exiting streams, gaseous stream and aqueous liquid stream. The gaseous stream exits at a flowrate of 5782,13 kmol/h with 390,3 ppm (wt./wt.) of acrylic acid and 23.98 ppm (wt./wt.) of acetic acid. It exits at a temperature of 70,13 °C and a pressure of 1 bar. The second exiting stream is the product stream at a total flowrate of 1576, 9 kmol/h. This stream contains 55.2 % (wt./wt.) acrylic acid (main product). It exits at a temperature of 81, 86 °C and a pressure of 1 bar. This stream is cooled to 46.5 °C prior to the LLE unit.
The product specification requires 100 000 tonnes per year of ester grade acrylic acid (minimum purity 94% (wt.) by oxidation of propylene (94% purity on molar basis). This acid product requires approximately 817.33 kmol/h of processed water. The use of packing columns is recommended for diameters less than 0.6 m (Seader, et al., 2011). The obtained diameter was 5,21 m, thus, a packed column couldn’t be chosen. Sieve trays (as opposed to bubble or valve-type trays) were chosen because of their ease of installation and lower cost compared to packed columns. The choice of sieve trays was also facilitated by their well-known design procedures, low fouling tendency and large capacity (Seader, et al., 2011). The design specifies a column with approximately 24.8 m of height, and containing 60 sieve plates. Processed water with 300 ppm of hydroquinone inhibitor is added to tray 1 (the top tray), and recycle stream is added at tray 69, one stage above the base stage. Single pass crossflow-type trays are employed for all the plates. The column operating pressure is 1 bar and the operating temperature range is from 69,85°C to 81.8 °C. A safety factor of 10% was accounted for in the design temperature and pressure. The total weight of a column vessel including the shell weight, plates and insulation is 1096,85 kN which is equivalent to 111847,55 kg. The absorption column and its associated structures (insulation, trays and vessel) are expected to cost in the region of R 8,8 million. Detailed calculations concerning the absorption column design are presented in Appendix F.

Papers by Retsam Fut

The South African sugar industry is one of the world’s leading cost competitive producers of high... more The South African sugar industry is one of the world’s leading cost competitive producers of highquality
sugar. However, this industry is currently experiencing a gradual decline due to numerous
challenges such as unfavourable climate conditions, economic decline, cheap sugar imports, the Health
Promotion Levy (“sugar tax”), and lack of required capital for innovation (SASA, 2020). This crisis
threatens tens of thousands of jobs and hundreds of thousands of livelihoods. As a result, this study
seeks to develop a strategy to mitigate part of the crisis faced by this industry. Recently, the Illovo’s
Sezela furfural production plant downstream to the sugar mill was commissioned. This plant produces
a waste with a sugarcane wax content of about 30% (R.D Gent, 2012), which is higher than the wax
(8.3%) extracted from press mud reported by J.M Paturau (1982).
The aims of this study are to assess methods of separating the wax from DAF mud, as well as a method
to refine the crude wax. Furthermore, the resulting waxes are to be characterised to allow for comparison
with conventional sugarcane wax as well as other plant-based waxes such as carnauba wax. Finally, a
preliminary process layout is proposed, and a mass balance of the overall process presented. This can
serve as a basis for future equipment sizing and costing exercises.
Two methods of producing crude wax from DAF mud are compared in this study, namely a solvent
extraction method and the, heating and melting method. The solvent extraction method involved
dissolving DAF mud in five different solvents namely, turpentine oil, toluene, butanol, 2-butanone or
ethanol. The heating and melting method involves heating the DAF mud to a melting point of crude
wax and collecting the resulting wax by decanting. The crude wax yield obtainable via solvent
extraction is in a range of 81-87 %, while the crude wax yield obtained via heating and melting is
approximately 56%. Despite the relatively low attainable yield of crude wax via this latter method it is
preferred over solvent extraction for the following reasons; eco-friendliness, cost effective, simpler, and
faster.
Both the crude and refined wax were characterized for their physico-chemical properties. Results have
shown that crude wax produced by heating and melting method has an acid value of 155 ± 2.2 (mg
KOH/g wax), saponification value of 227 ± 10 (mg KOH/g wax), % FFA of 78 ± 1, ester value of 72 ±
10 (mg KOH/g wax), Iodine number of 53 ± 5 (g I2/100 g), unsaponifiable matter (%) of 21.5 ± 2,
melting point (°C) of 76 ± 2, density (g/cm3) of 0.850 – 0.882 (at temperatures between 25 and 80 °C)
and refractive index (26°C) of 1.4923.
Crude wax is further treated with activated charcoal and ethanol to obtain refined wax, at a crude wax:
ethanol: activated charcoal ratio of 1:04:02. After crude wax has been refined, it is then characterised
for its physical and chemical properties. Refined wax characterization results shown
that it has an acid value of 23 ± 3 (mg KOH/g wax), saponification value of 59 ± 7 (mg KOH/g wax), % FFA of 12 ± 1, ester value of 35 ± 7 (mg KOH/g wax), Iodine number of 44 ± 8 (g I2/100 g), melting point (°C) of 75 ± 2, density (g/cm3) of 0.787 – 0.814 (at temperatures between 25 and 80 °C) and refractive index (26°C) of 1.4867.
The GC-MS analysis revealed that, similar to crude wax, refined wax predominately consists of five main classes of compounds namely, fatty acids, alkanes, alcohols, aldehydes, and esters. Fatty acids contributed about 50% to the total composition for both crude and refined wax samples. Furthermore, both crude and refined wax samples were found to contain policosanol, which can be used to support the evidence of the applicability of sugarcane wax derived from Illovo’s Sezela DAF mud in various applications such as pharmaceuticals industry.
The scaling up of the process was successfully implemented and the preliminary exercise on feasibility of the process was determined by developing a process flow sheet for the whole process and subsequent mass balances. Mass balances will be useful in equipment sizing and overall project costing which is part of the future work and beyond the scope of this study.
It was concluded that the crude sugarcane wax obtained from DAF mud is quite different from that obtained from filter mud. However, the ester number is in the range given in the literature for filter mud-derived sugarcane wax. The iodine number of the DAF mud-derived raw wax is much higher than that of the conventional filter mud-derived wax. The unsaponifiable matter is lower and the melting point is in the range reported for filter mud-based crude wax.
The DAF mud-derived refined wax of this study is compared to different wax fractions derived from conventional filter mud-based waxes. The saponification value lies within the ranges of “hard wax” and “refined wax”. The iodine number and the melting point of the refined wax from DAF mud lie within the ranges of “soft wax” and “hard wax”, respectively.
Furthermore, the DAF mud-derived refined wax’ properties was found to resemble those of candelilla wax rather than carnauba wax, with the acid and saponification values as well as iodine number being in the same ranges. The melting point is 2-4°C higher than that specified for candelilla wax. Future studies should focus on the market developments and application areas of candelilla wax, and include additional refining steps, if the carnauba wax market is to be targeted. In addition, future studies should evaluate the economic feasibility of the process by costing the overall project, investing in the equipment to produce a completely eco-friendly refined sugarcane wax.