Full electric processing with KEESTRACK "Electrifying results"
Five end products with a production capacity of 180 t/h and total diesel consumption of 60 l/h – those were the impressive key results of a multi-stage crushing and screening combination of four mobile Keestrack plants first publically tested in autumn 2016. The tests were conducted during the customer days of the Norwegian Keestrack dealer Fredheim Maskin and formed part of the technical premiere for the “full-hybrid” drive technology of the international processing specialist. Debuting within the full-electric combination powered by an external gen set were the all-new jaw crusher B4e and the mobile cone H4e – both with new drive systems, using diesel power only when needed.
Successful premiere
Using the traditional "Fredheim Demo Days" as platform to present its new full-hybrids was well planned by Keestrack. With again over 40 plant exhibits of several brands, the event in Spydeberg, some 30 km south-east of Oslo, exceeds the expectations of a normal “in-house” show and attracts specialist visitor from all over Scandinavia and other international markets. A record of 650 sold Keestrack plants in Norway and Sweden since 2005, made the company, led by the brothers Per Olav and Svein Fredheim, to one of the most successful Keestrack distributors – also reflected by the 2016 “Dealer-of the-year” award, presented for the eighth time to Fredheim.
Highlight at the Fredheim machine demonstration, with over 20 working plants in a granite quarry, was the full-electric tracked processing line. The Keestrack B4e jaw crusher with stacker S5e (for 0/20 pre-screen), the H4e cone with 3-deck-afterscreen module and the final 2-deck-classifier K3e for five end product fractions. With a feed size of 600 mm and different sets of end products, incl. double crushed chippings (0/2 … 16/22; 0/4 … 16/22), the combination reached a maximum production of 180 t/h. Without activating their on board-diesels all machines were powered through a single 500-kVA external gen set. Consumption analyses over several days gave average values of under 60 litres per hour.
"We were surprised by these results,” states Keestrack President Kees Hoogendoorn. “Even if these values are quite specific, they clearly reflect the high economic potential of our full-hybrid technology. Applied in a mobile multi-stage processing line, as presented here for the first time, it offers great advantages for the contractor. Not only in daily practice, but specifically in long-term evaluation if we consider lower maintenance costs and longer service life,” resumes Hoogendoorn the most important reasons for the consequent development of alternative drive concepts in his company.
Long experience
And indeed, at Keestrack the new „Full-hybrids” stand in a row with the early introduction of modern load-sensing systems in diesel hydraulic drives and the partial electrification of crushing and screening plants through the wide use of electric motors on conveyors and separator components. “Every new level in development brought important savings in diesel consumption,” explains Kees Hoogendoorn referring to the 20-30 % improvement steps, made through modern hydraulics, diesel-electric components and the external “plug-in” operation, which is today available throughout all Keestrack plant technologies. “With their substantially smaller hydraulic circuits our hybrid systems provide advantages in maintenance, availability and safety – especially when working in environmentally sensitive areas.”
While the screeners and conveyors on hybrid Keestrack classifiers and stackers are operated electrically – the diesel driven hydraulics only supplied hydraulic cylinders and crawlers – all Keestrack crushing units were up to now only powered directly through the on-board diesel engine. “Electric drives supplied via external gen sets or mains certainly offer high saving potentials, but without compromising the plants’ mobility, crushing performance and productivity, which depends today also on optional modules with high power demands,” Kees Hoogendoorn characterises the challenges in development.
"Zero-emission" crushing
As a first result of these changing technologies Keestrack presented on last Bauma the track mobile cone crusher H4 with 345 kW/330 KVA diesel/generator module, 132 kW electric drive for the crusher and extensively electrified conveyors and screening components. Despite its comprehensive equipment, including an optional 3-deck after-screen with oversize conveyor, the compact, transport friendly plant, weighs only 46 t and can be operated “plug-in”. Now Keestrack presented in Norway the full-hybrid model H4e, featuring an additional electric motor/hydro pump unit to supply all installed hydraulic functions (feeder, hydraulic cylinders, tracks) via external current without starting the diesel engine.
The all-new Keestrack B4/B4e jaw crusher is optionally available with conventional diesel-hydraulic drive or as full-hybrid “e-version”. With active 2-deck pre-screening and the re-designed 1100 x 700 mm jaw crusher featuring the patented N.S.S. overload protection. The new model follows on the successful Apollo/B4 for flexible recycling applications or medium-sized quarry operations with capacities up to 300 t/h. Completely equipped with new options, like the 1-deck after screen module with oversize conveyor, the new designed frame incorporating elements of high-strength Domex steel guarantees low transport weights (max. 49 t). The full-hybrid Keestrack B4e is equipped with a 242 kW diesel engine and a 225 kVA on-board generator. The latter supplies the 110 kW electric crusher motor, all other electric drives on conveyors and screens and the separate 55 kW electric motor/hydro pump unit for all installed hydro drives (cylinders, tracks). During “plug-in” operation (external gen set/mains) the diesel engine doesn’t have to be started, the whole energy management is controlled automatically including the electric supply of a secondary unit (screen, stacker).
