1. Dynamic compressor selector Dr. GD Bolt Date 16-08-2012

2. Mining compressed air overview POD – Point of Delivery (DSM) POG – Point of Generation (SSM) Other users (DSM) 12 to 30km

3. Supply side opportunities Compressed air generation (SSM) Compressor cycling Guide vane cycling Blow-off

4. Strategy Existing strategies First phase: SSM enables manual scheduling of compressor priorities and delivery set-points

5. Demand side opportunities Compressed air consumption (DSM) Pneumatic equipment has a minimum required pressure as specified by the OEM Increased pressure ≠ Increased performance Higher pressure = Larger losses

6. Strategy Existing strategies Second phase: DSM reduces pressure and flow at POD

7. Present system limitations Problems Regular specialised manual input Inaccurate system predictions Compressor and GV cycling still occurs

8. Dynamic compressor selector (DCS) Decision making; integrate DSM and SSM Pressure schedules at POD and system losses from the POG to POD are known and used to: Dynamically change compressor priorities and Change pressure set-points according to POD schedules. This new technology is called REMS-DCS

9. Dynamic compressor selector DCS divided into three major components Network simulation Compressor selection Compressor set-point adjustment

10. Network simulation Major/minor losses determined empirically POD pressure compared with required pressure profile The additional/excess flow is calculated

11. Compressor selection Compressor selector receives the system flow difference Selects best compressor or compressor combination to start/stop Compressor weights are used

12. Compressor set-points Minimum required pressure set-points determined from simulations

13. REMS-DCS Tested and verified using historical data Operate REMS-DCS in parallel with existing master controller

14. Conclusion Safe and efficient compressor set-point control using simulation Compressor cycling minimised Most efficient compressor combination selection Expected saving at Lonmin Marikana division of 3.3 MW (Eskom peak only) Estimate cost saving of R1,618,000 p.a. Questions?