Workshops 1995-1999

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Engineering and energy workshop on factory design, 24 - 28 Feb 1997, Pakistan


Florenal Zarpelon Chairman, Engineering & Energy Section

The ISSCT Workshop on Factory Design, organized by Shakarganj Sugar Research Institute at Faisalabad, Pakistan, from Feb. 23 to 28 1997, was a success. There was a total of 52 participants,among them 26 foreign.

The first two days delegates visited Shakarganj Sugar mill and distillery, Crescent Sugar Mill and particle board plant, Fauji Sugar Mill, and Shakarganj Research Institute.

Concerning the Workshop itself, there were very good contributions for all the themes reviewed. The technical session was opened with the topic Milling versus Diffusion which was covered by Dr. Peter Rein from South Africa. The advantages of the diffusion technology were emphasized and comparison between milling and diffusion covered the following aspects: in milling it is very difficult to obtain 97% extraction while 98% is normal with diffusion; power requirement for cane preparation is more or less the same for both but for extraction it is 50% less with diffusion and thus, there is an opportunity to export more energy; in a 300 tch mill an extra 2 MW can be obtained with diffusion. For a high extraction unit, the cost ratio between diffusion and milling can be figured out as follows: capital cost is of the order of 60%, total maintenance cost 57% and operation labour cost under average conditions is 50%. Juice heating is fundamental for diffusion in order to eliminate microorganisms and to promote rate of extraction; for this reason there is a slight overall increase in the process steam demand for diffusion. With regard to juice quality, it was pointed out that diffusion gives a lower starch and suspended solids content, with reduced purity and about 25% more colour. Diffusion is more sensitive to trash and gives around 6% more bagasse since all bagacillo is retained in the extraction unit. Filter cake produced under diffusion is around half. Lactic acid is much less in diffusion which means less microbiological activity. The issue of bagasse moisture was raised and it was mentioned that in Hawaii bagasse moisture from diffuser is of the same order as that from milling and whether milling or diffusion is practised, bagasse dewatering is governed by fine grooving, 400 pitch angles, adoption of messchaert grooves, hard facing, drain of the bagasse before getting to the mill and speed of the mill as low as possible to prevent reabsorption. Another important issue was in regard to change from milling to diffusion: the expansion of the capacity of the factory is a good opportunity for that purpose.

Sugar quality trends and sugar boiling design were covered by Dr. Ross Broadfoot, from Australia. A revision was made on the characteristics of mill white, refined and high quality raw sugar and sugar quality criteria based on colour, polarization, ash, suspended solids, moisture, dextran, starch, size distribution and temperature. A review of the process now being used in white end refinery attached to a raw factory, a stand-alone refinery and a direct mill white using floatation technology. An introduction to emerging membrane technologies was also presented, including New Applexion Process (ultrafiltration / juice softening) and Honiron ABC process (continuous screening, ultraclarification and absorption), and a review of recrystalization processes was given. Sugar boiling procedures used in different countries were presented to show the various options of the technology. Continuous boiling was covered by Dr. Rein; he emphasized that the problems related to encrustation are only encountered with high grade pans.

Power generation at high demand of process steam was presented by Florenal Zarpelon, from Brazil. A modern sugar factory is nowadays an energy complex where alcohol and other by-products are also produced. Under these circumstances maximization of power generation is a question of the optimazation of the energy (energy conservation or first thermodynamic law) and the optimization of the combination steam production and steam turbine, as stated by the second thermodynamic law. The process of mechanical vapour recompression (MVR) was discussed and the conclusion is that MVR is applicable to reduce fuel consumption under high demand of process steam; it is not effective to improve power generation. Boris Morgenroth, from Germany, presented the results obtained using the Balcke-Durr falling film plate evaporator in South Africa. Robert Kwok, from Hawaii, gave an overview of the bagasse gasification demonstration plant installed at Paia mill.

Sugar drying and conditioning was covered by Dave Meadows, from South Africa. He presented the main types of sugar dryers used in the sugar industry and the problems related to sugar storage.

On the theme “Green cane factory impacts”, a very interesting presentation was made by Robert Kwok on “Effect of green cane harvesting on factory operations in Hawaii”. He mentioned the strong environmental resistance to cane burning in Hawaii since the island economy is heavily dependent on the tourist industry. The operation with green cane results in a number of problems, among them were mentioned: lower washing efficiency of the cane, problems of cane preparation, low milling rate, reduced mill extraction, mill slippage, high ash in bagasse, poor burning of bagasse, poor clarification, high juice colour, low crystallization rate, high viscosity, poor sugar quality. The “impacts of extraneous matter on sugar factory recovery” was presented by Muhammad Qureshi, from Pakistan, who discussed the high losses in Shakarganj Mills due to cane trash.

Trends on steam Generation were presented by George O Reilly, from South Africa. He made a real contribution since he replaced John Briggs of Foster Wheeler, Canada, who could not come to the Workshop. George discussed general aspects of boiler design, emphasizing grate design, gas cleaning, ash disposal, rate of steam production, air heater and economiser.

Dr. J. Bhagat, from India, covered the topic “Economics of small mills”. A good discussion was undertaken on this subject, and the conclusion was that it is difficult to establish a comparison among countries since different conditions are present.

Philip Steiner, from South Africa, gave an overview on “Minimum staffing, automation and control”. It was shown that automation provides real information to make a decision for optimum plant performance. The Komati Mill in South Africa, with its centralised control room, intelligent devices and distributed controls systems, was mentioned as an example of a modern automated sugar mill.

Other general topics were covered by Dr. Mohammad Munir, from Germany (Sugar graining techniques), Abdul Q.Khattak, from Pakistan (Factories handling beet and cane simultaneously), Peter Jais, from Brazil (High throughput of Brazilian mills).

Agronomy, Irrigation, 15 - 19 September, 1997, Bureau of Sugar Experiment Stations (BSES) - AUSTRALIA

September 15 to 19, 1997,Townsville, Australia
G.C. Soopramanien, Chairman, ISSCT Agronomy Section

The irrigation Workshop was organised by the BSES and the organising committee was chaired by Mr G Mc Mahon. The committee had the support and close collaboration of the following orgnisations/institutions: Cane Growers, Sugar Research & Development Corporation and CSR. It was attended by 52 delegates from 15 countries. It started by a two days tour from Mackay up to Townsville where the scientific discussions took place.

Most of the areas visited need supplementary irrigation. Soils vary from alluvial to heavy clays as well as sodic soils. Water is not freely available in all areas. A number of farmers have been over-using borehole water with the result that salt intrusion has occurred in some areas. There is more or less a consensus that it would be better if growers’ associations or water users groups were to take over water management for their respective districts. It was clear that Australian cane growers are aware that sustainable cane growing requires an immediate improvement of water use efficiency (WUE) minimising soil erosion, reducing effects of water logging as well as ensuring that the community becomes aware of the action undertaken by farmers with respect to the environment. Thus visitors were able to visit and discuss: the surge flow technique, the use of flexible flumes, optimising furrow length as well as tail water recycling in order to increase WUE under furrow irrigation. Some farmers are now irrigating with travelling guns or low pressure booms. The latter equipment is lighter than previous models, it can be folded but irrigation spray is seriously affected by strong winds. The combination of trash blanketing and the travelling gun seems to be a satisfactory answer for some growers who find that trash on the pathway for the equipment is as good as grass.

Drip irrigation is increasing in popularity particularly with those who need to devote more time to other field tasks. The new drip line T-tape has already been installed over an area of about 1000 ha. The farmers up to now seem to be satisfied with this form of irrigation with respect to water saving as well as cane yield. One grower felt that with drip he will be able to increase his cropping cycle (up to the 5th or 6th ratoon).

It was interesting to note the close collaboration between research scientists and the growers via the extension services of BSES. Thus a number of farmers were trying the mini-evaporation pan or tensiometers for irrigation scheduling.

Although the Burdekin area is the most productive sugar can region of the world, the growers are still “on the alert” for more adapted varieties (to reduce dependency on Q124 – the most popular variety at present), new technology for water management and more efficient planting and harvesting machines. On-farm trials with narrower inter-row spacing have started whilst machines are being modified for both furrowing and harvesting at higher planting densities.

The technical sessions covered the three irrigation methods – i.e. surface, overhead and drip/trickle as well as water use efficiency (WUE) and finally irrigation and the environment. Very often growers have to consider shifting from surface or overhead to drip irrigation. There are various constraints which must be considered and the conversion is not always in favour of drip in view of available infrastructure, the cost of drip and the level of management. The disposal of drip tubes after one crop cycle is a problem still to be resolved. Results available not only from Australia seem to indicate that under certain soil conditions it might be preferable to drip irrigate cane every three days or when soil moisture potential around the root system reaches 30 KPa. This needs confirmation from the various trials under way. The wetting pattern under drip is a key element governing the choice of emission rate, inter-emitter spacing and the placement of the drip lateral (or tubing). The Environscan is a new piece of equipment which may be used as well as the Time Domain Reflectometry (TDR) and Neutron moisture meters for assessing the wetting pattern. Data collected in Australia have led to recommendations for water application for a range of soils in Bundaberg. It was interesting to note that one irrigation firm has now a machine to extract its drip tubing.

WUE, irrigation scheduling, deficit irrigation and off-site effects of poor irrigation management were given special attention during the technical session. It is worth recording here, two mini-pans which were proposed to small or medium growers for irrigation scheduling. In a few countries in view of scarcity of water over a a period of two to three months, deficit irrigation has to be practised. The results todate indicate that stressing cane during the tillering phase is less harmful to yield than a water stress during the elongation phase.

Modelling and simulation studies are also increasing in popularity among irrigation scientists. It was felt that some time should be devoted to field data collection to validate or calibrate models. It was also felt that irrigation efficiency and profitability may be ensured when growers are provided with ample support and training in the operation and management of novel irrigation methods or equipment.

Molecular Biology/Pathology, 12 - 16 May, 1997, Host: South Africa Sugar Association Experiment Station (SASEX)


12-16 May 1997, South Africa
R. Bailey, Chairman, ISSCT Pathology Section & P. Moore, Chairman, ISSCT Molecular Biology Section

The workshop was attended by 62 delegates, including 47 from outside South Africa and most of the worlds leading sugarcane researchers in the two disciplines. Seventeen countries were represented. The excellent attendance contributed greatly to the success of the meeting.


A total of 42 verbal and 22 poster presentations were made under six session topics. Most of the technical and discussion sessions were held as joint meetings. The session topics were:
Yellow Leaf Syndrome (YLS): 1 invited paper, 9 papers, 2 posters
Genetic Engineering: 1 invited paper, 7 papers, 6 posters
Molecular Biological Studies on Leaf Scald, Viruses and Smut: 8 papers, 6 posters
Ratoon Stunting Disease (RSD): 6 papers, 4 posters
Genetic Markers: 1 invited paper, 3 papers, 2 posters
General Sugarcane Pathology (Pathology only): 6 papers, 2 posters

Three invited speakers established a high scientific standard for the workshop proceedings:
Dr Anna Tymon (IACR-Rothamsted, UK) – Phytoplasmas: detection, diagnosis and classification
Dr Robert Birch (University of Queensland, Australia) – Progress and technical limitations to practical application of transgenic sugarcane Dr Jean Christophe Glaszmann (CIRAD, Montpellier, France) – Molecular markers for sugarcane genetics

Visit to SASEX

Delegates visited the SASEX facilities at Mount Edgecombe on 14 May. After addresses by Mike Matthews (Executive Director, SASA) on the South African sugar industry and Roger Bailey on the disease situation in the industry, the delegates toured the Biotechnology, Pathology and Plant Breeding departments to view work in progress. A highlight of the visit was the demonstration by Dr Pieter Cronjé of his work on the YLS phytoplasma.

Post-Workshop Tours

The tour from 18-21 May was attended by seven local and 32 foreign delegates. Accommodation was at the Umfolozi and Bonamanzi game reserves in northern KwaZulu-Natal. The tour included visits to the SASEX field station and the Illovo Sugar transplant nursery at Pongola, and talks on strategies for disease control or small scale growers in the Umfolozi area.

Technical report

On request, the technical report of the workshop can be mailed electronically to those interested Contact Roger Bailey (ISSCT Pathology Chairman) at

Joint Agricultural Engineering & Factory Processing, 24 - 28 November, 1997, Effect of Field Mechanization on Factory Performance Host: Centro de Investigacion y Asistencia Técnica del Estado de Querétaro. A.C.(Ciateq) - MEXICO


Dr. G. De Beer and Dr. Brian Purchase,
Chairmen of Agricultural Engineering and Factory Processing


This Workshop was hosted by CIATEQ (Centro de Investigaion y Asistencia del Estado de Queretaro) and GEPLACEA (Group of Latin American and Caribbean Sugar Exporting Countries) in Veracruz, Mexico.

It involved the Agricultural Engineering and the Factory Processing Sections of ISSCT, with the chairmen of these sections arranging the technical programme whilst the hosts attended to publicity and local arrangements. The workshop facilitated informal interaction between field and factory personnel and it promoted better understanding of the changes in harvesting techniques which are currently taking place in many sugar industries. The list of participants includes delegates from 18 countries with 50 from outside Mexico and 26 from Mexico.

Field visits involved one day of travel in the Veracruz region with interesting visits to a range of facilities including a harvesting system where hand cut cane is placed in metal frames ready for mechanical loading thus avoiding contact with soil.

Harvesting trends towards increased mechanisation and increased harvesting of green cane were identified and the possible impacts of these trends on factory operations were discussed. The challenges of potential increases in soil and leaves associated with mechanical and green cane harvesting were analysed and in a final interactive session delegates contributed ideas to a list of advantages and disadvantages of green cane harvesting from the perspectives of farmers, harvesting contractors and sugar factories.

The discussions were conducted under the headings of: Orientation cane production, delivery and processing Available harvesting systems The impact of fibre on the factory Variety selection for mechanical harvesting and quality Fire as harvesting aid and its effect on quality Alternate uses of trash Factory performance as affected by tops, leaves, soil and stones Agronomic measures to improve cane presentation and quality Factory performance as affected by sucrose content, juice purity and cane deterioration Cane loading, transport systems and transport scheduling Cane yard management Cane cleaning Cane payment schemes Current trends and challenges Diffusers and their implications for cane quality Green cane harvesting and its implications for field and factory.

Formal proceedings of the workshop will not be published but a report of presentations and discussions may be downloaded from this web page.

5th ISSCT Breeding & Germplasm Workshop, 18 - 22 May, 1998 Efficiency of Sugar Cane Breeding Host: Mauritius Sugar Industry Research Institute - Reduit


18-22 MAY 1998




VENUE: The workshop was held at a beach hotel on the north coast. There were at least three days of discussions in the hotel, a whole-day visit to MSIRI and a field visit.

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Themes and Communications