Client: Terragen Ltd. (Terra Mauricia Ltd.)
Industry: Power and Energy
Region: Plaine des Papayes, Mauritius
Product: 4 X AGF33D Autonomous Gravity Sand Filters – Double Decker Version ± 15 Mld
Installation: 1999

Challenge

• Terragen Ltd. owns a 2 x 35 MW thermal power plant, producing around 370 GWh of electricity annually from bagasse and coal.
• Cooling systems are the most water-intensive part of the thermoelectric generation process.
• Cooling towers scrub large volumes of air and effectively remove solids. Tower water adds suspended solids from the tower and process leaks.
• If allowed to settle, these solids lead to significant losses in efficiency and increased costs.
  • A layer of foul or scale measuring 25µm thick can reduce heat transfer to increase energy costs by as much as 10%.
• The solids consume chemicals used to prevent scaling and corrosion.
  • As a result, dirty water requires more chemicals and receives less effective treatment than clean water.
• Of the numerous water quality parameters that may affect performance, suspended solids are the most common and serious culprit. Therefore, the benefits of removing particles from the system are numerous.
• During the design phase of the water treatment plant for Terragen Ltd., process engineers looked for the best side-stream filters.
• They required:
  • easy, drop-in installation
  • effective and efficient filtration
  • high reliability and durability
  • lowest lifetime costs
  • low maintenance
  • small footprint

Application

• Side Stream filtration of cooling water.

Solution

• The inherent simplicity, high efficiency and low operating costs of AGF autonomous gravity sand filters make it the ideal filter to install on side stream filtration applications. AGF filters offer:
  • Easy Installation:
    • Minimum civil works on site
    • Fabrication under tightly controlled factory conditions
  • High effectiveness & efficiency:
    • Our AGF filters have a 40-year track record of effective filtration – across a range of industries and application
    • The lowest lifetime costs translate to the highest efficiency
    • Autonomous operation ensures that filters only backwash when required, minimising water losses
  • High reliability and durability:
    • 100% Mechanical, with no moving or rotating components
    • No peripheral components
    • No automation obsolescence, valve and electrical maintenance
    • Units in active operation for 30+ years
  • Lowest lifetime costs
    • Once the required head is established, no further energy is required
    • The head is often freely available in the system
  • Low Maintenance Costs:
    • Maintenance is limited to oversight functions and periodical replacement of media and nozzles
  • Small footprint:
    • With Superior Filtration’s AGF “D” model, the footprint is reduced significantly
    • Effectively doubling the filtration surface area on a single footprint
  • 4 x AGF33D Autonomous Gravity Sand Filters
    were installed, processing 600m3/h at an average filtration velocity of ±9m/h.

Results

• AGF filters effectively remove suspended solids from the system, resulting in:
  • Lower energy consumption
  • Improved chemical performance
  • Lower maintenance costs
  • Improved productivity and less downtime
• AGF filters have added these benefits consistently for decades. At this plant – for 25 years and counting.

Client Experience

“The filters don’t have any PLC, valve, nor motor for backwash, so no worries about automation obsolescence, valve and electrical maintenance.”
Jean-Marc IWEINS – Power Plant manager