1. Oil Production Process
Team 20: Golden Oil
Emma Huynh, Preston Ji, Charlotte Ntim, Maame Sarpong, Class of 2018
Introduction
Oil Production Process
Solvent: Hexane
Low toxicity
Relatively inexpensive
Burn before release
Project Inspiration:
As a major sesame producer (~4% of worldwide market), South Sudan has a strong tradition of cultivating sesame, a crop which has become indispensable to the economy of the nation and the culture of its people. However, the young and emerging nation of South Sudan lacks the industrial capacity to process its seeds into oil. Therefore, we are inspired to explore a chemical engineering solution to this problem.
Sesame Seed and Oil:
Sesame grows in tough climate conditions and its seeds have the highest oil content (~50 wt%) among the common oil seeds. Sesame oil is composed of linoleic acid (41%), oleic acid (39%), palmitic acid (8%), stearic acid (5%), and other species in small amounts. The remaining cake is rich in protein and sugar, making it a valuable by-product for animal feed.
Process Summary:
Sesame seeds (G) are roasted and ground, at which non-solvent oil (O) is collected.
Grinded sesame cake (G) contacts hexane (B) and the remaining oil (R) is dissolved out of the solid.
Hexane is evaporated in cascade flash drums, with increasing temperature and decreasing pressure.
Residual hexane is stripped with N2 (P) in a tray column and recycled.
Solvent extracted oil (O) is collected.
Hexane is evaporated from sesame cake, which is collected for animal feed.
Grinder: Screw Press
50~60 0C, 100 kPa
Break up seeds to 300~600 μm diameter particles
Assume 50% of total oil extraction
Left to right:
Preston Ji, Charlotte Ntim, Emma Huynh, Maame Sarpong
Results
Leacher: Hexane Shower
50~60 0C, 100 kPa
Pass sesame cake on conveyor belt through showers of hexane
Utility
Steam
Cooling water
Fuel (NG)
Economic Analysis:
We calculated the capital and operating cost based on the general design (Figure 1):
Criteria: 15% rate of return, 20 year plant life
Oil break even price: $2,670/t
Oil Market price: $2,870/t (as of 11/10/2017)
However, the above analysis is preliminary because (1) some optimization remains to be completed and (2) our design and cost data come from US sources, (3) the economy of South Sudan is unstable and inflation rate is high, and (4) the infrastructure of the country is poor. Therefore, the plant of interest can easily become unprofitable if implemented.
Our Conclusion:
In addition to profitability concerns, our project may have various negative impacts such as the consolidation of agriculture and the dissolution of traditional society. Presently the country may not be prepared to absorb such impacts. Overall, we conclude that though the design may be feasible in the US, it remains a high risk operation in the South Sudan context.
Objectives
Figure 1: Schematic PFD of the Overall Process
Hexane Recycle: Coolers and Pump
Condense and pump back to leacher
Recover 97~99% hexane
Design a plant producing sesame oil via mechanical pressing following by solvent extraction.
Production scale: 10,750 t/yr, 1% of the worldwide sesame oil production
Design selected major equipment and specify the operating conditions.
Estimate the cost of the desired operation.
Evaluate whether the project is feasible.
Hexane Recovery: Flash Drums
Feed: hexane-oil mixture
Top outlet: hexane vapor
Bottom outlet: oil and hexane, until 1~3% solvent remaining
Stage 1: ~80 0C, 60 kPa
Stage 2: ~120 0C, 40 kPa
Stage 3: ~150 0C, 20 kPa
Oil Product
Purity: < 20 ppm hexane (mass)
Carrier Gas: N2
Store as liquid
Burn the off gas (with hexane)
Acknowledgement
We thank Professors Chad Tatko, Jennifer VanAntwerp, Jeremy VanAntwerp, and Wayne Wentzheimer, advisor Dr. Phil Bronsema, and Zeeland Farm Services Inc. for their assistance.
Figure 2: Schematic PFD of the Detailed Design of Hexane Recovery Section