Modelling the flows through a shredder

It is well established that good preparation is a prerequisite for good extraction, yet many mills today are not achieving the nominal benchmark of 90% pol in open cells. In some cases, the low preparation is the result of insufficient power available to the shredder. In most cases, however, adequate power is available but 90% pol in open cells is not being achieved. It is also well established that there is a strong link between power consumption and preparation. If sufficient power is available but good preparation is not being achieved, it is likely that the available power is not being consumed. Following recent work by Wilmar Sugar, a different set of guidelines for the design of the shredder grid has been proposed. While it is known that grid spacing, depth and wrap affect preparation, the optimum configuration is not known with certainty. This paper describes initial modelling that has been carried out to predict the flows of air, billets and prepared cane through a shredder and associated shredder air flow measurements. Thoughts on the way in which these flows affect preparation are presented

Studies on the clarification of sugarcane juice containing slow settling mud

To remain globally competitive the Australian sugar industry must achieve high manufacturing standards irrespective of the quality of the cane supply in order to maintain sugar quality. The presence of soils and colloidal particles in the manufacturing process presents challenges in the clarification process which ultimately affect throughput, yield and quality of the sugar. This thesis titled, "STUDIES ON THE CLARIFICATION OF SUGARCANE JUICE CONTAINING SLOW SETTLING MUD" examined the properties of soil samples received from different cane growing regions and obtained relationships between impurities in the soils and the impact on settling behaviour

Evaluation of mud filtrate clarification to improve factory performance

Clarification performance and flocculant dosage is strongly linked to the mud solids loading in the feed entering the clarifier. The recycle of filtrate can represent an extra ~10-15% mud solids loading on the clarifier, thereby reducing its effective capacity. Filtrate recycling may cause significant increase in turbidity, complexed calcium ion formation, phosphate, proteins and polysaccharides in mixed juice that impact on evaporator scale formation and molasses exhaustion. The paper details the results obtained from laboratory, pilot scale and factory trials of filtrate clarification using both sedimentation and flotation methods. Clarified filtrate could be produced of similar quality to ESJ. Filtrate clarification was able to significantly remove insoluble solids, turbidity, phosphate, and polysaccharides content with slight reductions in minerals content of the filtrate. On the basis of improved filtrate quality, the clarified filtrate could be directed to ESJ, instead of the normal practice of directing the mud filtrate to mixed juice. The potential impacts of implementing filtrate clarification are discussed in respect to improved performance and throughput of the clarification station

The need of bagacillo in processing?

THE HISTORICAL USE of rotary vacuum filters in the Australian sugar industry to recover sugar from the clarifier mud has dictated that some bagacillo is allowed to flow through juice screens and subsequently into the clarifier mud stream to improve the porosity of the mud cake that develops on the rotary vacuum filter screen and hence improve washing efficiency and juice drainage. In some cases, particularly at times of high soil loading in the cane supply, additional bagacillo is added at the mud mingler. This bagacillo is usually removed from bagasse by the use of a pneumatic separator and often results in the addition of larger pieces of bagasse to the clarifier mud. There are alternatives to rotary vacuum filters that produce lower moisture mud cake. For example, decanter centrifuges are used in some Indian sugar factories to reclaim the pol content and reduce the moisture content of clarifier mud. The need for low energy use in such factories puts a monetary value on the bagacillo, which, if retained in the bagasse, provides additional fuel for the boiler station. Another alternative are vacuum belt press filters, many of which have been installed in Central and South America. One vacuum belt press filter is in operation at Pioneer Sugar Mill working in parallel with rotary vacuum filters. These alternative mud processing technologies are claimed not to require fibre for adequate performance. The absence of fibre in the mud feed reduces the amount of filter cake produced and hence potential sugar losses may also be reduced. Fibre reduces the dewatering capability due to its hygroscopic properties, which leads to production of higher moisture mud cake. Furthermore bagacillo can reduce the throughput of decanter centrifuges and cause blockages. Any fibre not retained in the mud cake can cause detrimental effects in subsequent processing operations and final sugar quality. This paper discusses, for a typical Australian sugar factory, the effects of bagacillo on the clarification performance, on the adoption of alternative technologies, on the quantity and composition of filter cake and resultant sugar losses in the mill mud, transport costs to the field, and on sugar quality

Slow settling behaviour of soil nano-particles in water and synthetic sugarcane juice solutions

Surface chemistry, morphological and physical properties of nano-particles in soils affect the settling behaviour of suspended particles in sedimentation clarifiers used in the raw sugar manufacturing process. This paper reveals subtle differences in the chemical specie compositions between soils that have good settling behaviour and those that do not using x-ray photoelectron spectroscopy (XPS) and time-of-flight secondary ion mass spectrometry (TOF-SIMS). TOF-SIMS was further used to provide an understanding of differences between wet and dry soils that influence their settling behaviour. Differences in packing arrangements of the nano-particles in the soils and the presence of inter voids between individual particles and between microflocs, as revealed by high resolution microscopic techniques, provided evidence that the use of high density particles such as sugarcane bagasse fly ash was effective in increasing the settling rate of slow settling soils.</p

A factory experiment to assess different shredder-hammer configurations

Shredding is critically important to maximising the amount of pol extracted from the supplied cane by the milling tandem or diffuser. Whilst modern shredders typically achieve high levels of preparation (greater than 85 POC), they also use considerable energy, have high maintenance costs and produce much noise. An experiment was undertaken at Rocky Point Mill during the 2016, 2017 and 2018 seasons to evaluate the effect of shredder-hammer configuration on shredder performance in terms of POC, windage, noise, hammer wear rates and hammer-tip wear rates. Two hammer configurations were tested: a conventional checkerboard configuration (114 hammers) and an ‘Alternative 1’ configuration (152 hammers). The results showed that, although there were 33% more hammers in the ‘Alternative 1’ configuration, the POC was surprisingly lower at 87 compared to 88 for the conventional configuration. Furthermore, the mean specific power, noise levels and windage were slightly higher for the ‘Alternative 1’ hammer configuration. The wear rate for the hammers and hammer tips were~40% and ~68% higher in the ‘Alternative 1’ configuration, respectively

Current perspective and future research directions on defecation clarification for the manufacture of raw sugar

Juice clarification is integral to the sugar-manufacturing process and determines the quality of clarified juice which is subsequently processed to produce sugar. Clarification performance is defined largely by turbidity of the clarified juice, but the presence of soluble impurities, colour and colour precursors, polysaccharides and proteins influence heat-transfer performance of evaporators and vacuum pans, the crystallisation performance in vacuum pans and the achievable yield and quality of sugar. The conventional defecation process is inadequate to remove these non-sucrose impurities, and the gradual worldwide transition to green-cane harvesting is introducing greater levels of impurities into the cane supply. As a result, the clarification station is now having to deal with not only the endogenous impurities (e.g. stalk impurities) but also the trash (leaves and tops) impurities. This paper reviews work that have been conducted over the years to remove these impurities and presents future research directions that should improve clarification performance. Examples of future research directions include development of multi-functional nanoparticles to significantly improve impurity removal; processing strategies to enhance precipitation of proteins and polysaccharides; and ballasting and adsorbent agents