The findings were part of the Australian Coal Association Research Program (ACARP) funded project, Review of Regenerative Technologies to Increase Longwall Advance Speeds, undertaken by WBM and submitted to ACARP late last year.
According to WBM project manager Russell Smith it was perceived in the industry that longwall hoses connecting pumps and roof supports introduced significant flow restrictions into the fluid path, and compromised system performance.
The largest flow demands occurred during leg raise. When a leg lowers, it only needed one tenth of the fluid volume used during leg raise, and the fluid must be returned to the tank over a long hose path.
Regenerative technologies are aimed at eliminating the distance the fluid travels through, transferring the fluid locally during “leg lower” to a nearby roof support undergoing roof raise. As such, only the small “leg lower” volume is supplied by the pumps.
“Based on the results of the dynamic modeling, WBM concludes regenerative technologies are unlikely to offer a viable benefit to longwall performance. This outcome is driven primarily by the realisation that the long hose runs in modern longwalls are not the critical influence they are commonly perceived to be,” Smith said in his report to ACARP.
Smith also found extra valves were required to implement regenerative technologies, and these further degraded the system performance.
“Additional valving implementation and maintenance costs could be more effectively invested by purchasing improved conventional hydraulic systems [better valves and control strategies, etc],” he said.
Having established regenerative technologies to be unfeasible, WBM identified and documented the principals that would provide the basis for real performance gains in longwall hydraulic systems.
