For a single engineering solution with security level settings for plant access control and robust redundancy in one of Tanzania's major sugar projects, system's integrators, Industrial Technology & Systems Integration (ITSI), turned to Adroit's supervisory control and data acquisition (scada) package to ensure that only authorised operators have access to designated plant areas at leading 24/7 sugar producer, Kagera Sugar, in Bukoba, Tanzania.
ITSI is an industrial systems integration company offering clients single-source solutions for integrated plant control and information systems across most industrial sectors. The company offers specific expertise in programmable logistic controllers (PLC)/scada applications with additional strengths in manufacturing execution systems (MES) and personal information management systems (PIMS).
Kagera Sugar was handed over to Sugar Industries Limited (SIL, a local Tanzanian company associated with Super Group of Companies) in 2001. The privatisation is part of the government's Economic Reform Programme. SIL now manages the company using the expertise and experience of The Agricultural Consultancy Services (Mauritius) Limited (ACSL). The new management's first focus was on the rehabilitation and expansion of the company; promotion of the company and transfer of technology and management skills to the local workforce without forgetting improved care of the environment.
"The idea of having one system to maintain instead of four separate solutions as could have been dictated by the plant control areas was the engineering focus," says Andrew Godfrey, operations director of ITSI about implementing a single solution across three separate plant operating areas.
"The reason we chose Adroit was very simple. We have always felt that the support from Adroit Technologies is the real strength of the product. As a technical solution Adroit need step back for no-one either. A lot of time was spent building wizards before and during implementation. This assisted greatly with system configuration and will continue to assist with plant maintenance and growth."
General manager of the Kagera mill, Butch Carr, says, "The initial design crushing capacity of 125 tons of cane per hour will be expanded to 250 tons of cane per hour in 2007. Sugar production will initially be around 27 kilotons per annum and is planned to increase to 100 kilotons per annum by the year 2010."
The Kagera sugar cane estate and mill are concerned with the agricultural production of sugar cane, which it irrigates with centre-pivots ranging from 70-100 hectares each. The company harvests this sugar cane for crushing and processing to produce raw sugar for distribution on the local and international markets.
The plant has a total of about 8000 tags and 3500 scanned I/O. Approximately 80 PID (proportional integral derivative) controllers with associated tuning parameters/trends are monitored by the Adroit system. Trending is used extensively in the plant system. Operators view trends per plant area and this data is used for control adjustments. Printers are installed at each of the three control rooms specifically for generating event and trend printouts.
"We also separated the alarming with audibles per plant area. Area 'A' operators, for example, are therefore not unnecessarily bothered by alarms that do not apply to them," says Godfrey. "Robustness, scalability and reliability of the scada are all very important to the project. Sugar milling is a continuous process, and all parts of the process need to be running at all times."
Redundancy has been incorporated into the system at scada server level only. The design was built around a brief for a 'simple and robust' product with 'easy, fast replacement' of network components by any readily available manufacturer. "What impressed me most about the Adroit architecture is that the redundancy is reliable, and the client/server connection is simple and fast," says Godfrey.
Typical process control instrumentation was used in the plant with one slight variation. Much of the flow control is achieved by variable speed drives rather than normal control valves.
Two cluster servers were used for redundancy, with three additional workstations. The four separate Allen Bradley CLX PLC systems use Allen Bradley RsLinx software with Ole Process Control (OPC) server topics to connect to the instrumentation. The Adroit Ethernet OPC client in turn connects to each RsLinx OPC server. The factory was originally built in 1978 and shut down in 1997 until its privatisation in 2001 when rehabilitation commenced.
Through the provision of jobs and the creation of industry, the project has brought greater prosperity to the North Western region of Tanzania. Godfrey says, "This is the first time in 20 years I have seen economic upliftment so immediately apparent, even during the project construction/commissioning phases."
In conjunction with fellow Durban-based consulting engineers and project managers, Bosch Projects (part of the B&A Group), ITSI completed the project in November 2004, just one month after the plant re-commenced operations. Today Kagera is recognised as one of the major sugar projects in the country, striving for International Sugar Standards and competing with other sugar producing countries in Africa. Kagera's business plan for the future is to have more than doubled its cane sugar production ability at international quality standards.
For more information contact Megan Davidson, Adroit Technologies, 011 658 8100, [email protected], www.adroit.co.za
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