Issues pertaining to cane supply reliability and stockpiling at the Umfolozi sugar mill - model development and application.
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Date
2011
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Abstract
The co-owned Umfolozi Mill area has developed as an integrated supply chain. Cane
supply reliability was identified as a potential area for productivity improvement at
Umfolozi. It is important that the cane supply to a sugar mill arrives at a steady and
reliable rate. A reliable cane supply ensures that the mill can operate at an optimum
efficiency. Sugarcane supply reliability depends on how the mill area adapts to
unforeseeable changes in the supply chain. An important aspect to this is the weather
and how it affects the harvesting regimes. The sugarcane supply chain at Umfolozi is
divided into two branches, road transport and tram transport. The trams account for
70 % of the cane delivered to the mill and the can is sourced from a climatically
homogenous region. In the occurrence of a rainfall event of above 5 mm, infield
harvesting cannot take place on the Umfolozi Flats; hence 70 % of the mill‟s supply is
halted for one or more days. To address the problem, a stochastic model was created to
simulate the effectiveness of an enlarged cane stockpile if it were maintained on the
current tram sidings outside the mill and were crushed when wet weather prevented
further harvesting. The stockpile was simulated on a first-in first-out principle and was
able to supply the mill with enough cane to continue running for 24 hours. The model
was then used to conduct a series of Monte Carlo simulations on which sensitivity
analyses and economic feasibility assessments were carried out. Results show that the
stockpile was effective in reducing the length of milling season and the number of no-cane
stops. However, on further analysis into the implications of creating a stockpile it
was found that 1% recoverable value (RV) was lost during the 24-hours that the cane is
stored outside the mill. The loss in revenue as a result of the RV reduction had a
negative impact on any savings created with the implementation of the stockpile. This
result made apparent the negative impact of deterioration to the whole supply chain.
Further research is required to determine more accurately the rate of deterioration, and
therefore, quantify more accurately the losses that occur in the supply chain. A
significant outcome of the study was the development of a mechanistic tool which drove
decision making at Umfolozi Sugar Mill. It lead to the development of the modelling
framework LOMZI, a simulations based framework which places more emphasis on
environmental factors and risks.
Description
Thesis (M.Sc.Eng.)-University of KwaZulu-Natal, Durban, 2011.
Keywords
Sugarcane--Transportation--KwaZulu-Natal., Sugarcane--KwaZulu-Natal., Sugarcane industry--KwaZulu-Natal., Sugar factories--KwaZulu-Natal., Theses--Bioresource systems.