Research projects are moving the electronically controlled engine closer to reality, however, several major hurdles surrounding explosion protection still remain. While these hurdles are overcome it is important for operations to take advantage of the technologies currently available to reduce worker exposure to diesel particulate.
One manufacturer that within a few weeks may have the first ever certified electronically controlled engine for underground coal mines in Australia is Voest Alpine Mining and Tunnelling (VAMT).
The utility vehicle manufacturer currently has the electrical components of a 242kW electronically controlled engine at SIMTARS (Safety in Mines Testing and Research Station) for underground certification. The engine is rated Tier 2 under US EPA grading and has so far passed mechanical testing at TestSafe Londonderry. At the time of print the engine’s electric components were undergoing testing and results were expected towards the end of March.
The engine will be fitted to VAMT’s ED20 loader, and if approved will be certified for group one gases (methane), allowing it unrestricted access bar hazardous areas, consistent with all present underground vehicles.
VAMT engineering manager Phil Nelthorpe said the engine had been designed to overcome problems of high external temperatures and flame-proofing.
Water jacketing was utilised on the turbo charger compressor and the supply pipe to the charge air cooler. VAMT employed a Caterpillar marine engine to take advantage of existing water-cooled exhaust components to reduce the changes required to meet surface temperature limits.
Much of the push towards electric engines can be traced back to the US and European Union (EU), where tougher emission standards are forcing engine manufacturers to produce electronically controlled engines to meet these standards. Caterpillar plans to cease non-electronically controlled engine manufacture in the US by 2005-07 and all other manufacturers are likely to follow suit.
“Our engines tie in with suppliers' feed, which is influenced by the biggest markets -- the US and the EU on-highway truck market. In turn, all those engines are either driven by US EPA requirements or the equivalent in the EU. No one is going to build a special engine for a tiny market like the global underground coal market, let alone the market in Australia which is smaller again,” Nelthorpe said.
This thinking was backed by Construction, Forestry, Mining and Energy Union representative Stuart Vaccaneo who last year attended a US diesel particulate trip, which included a visit to the Caterpillar factory. Vaccaneo said much of the work to modify motors to meet flame-proofing standards to be used on the face would have to be done by diesel machine manufacturers such as Eimco and DBT, as major engine manufacturer Caterpillar would not be able to justify the effort on sales.
“The US factory alone produces somewhere in the region of 400 motors per day. At the present time the underground coal industry worldwide introduces some 100 new motors per year. Given this, it is extremely unlikely Caterpillar will expend much time, effort or money on making special modified versions of the motor for use in the face areas of mines,” he said.
“Under US legislation it is up to the manufacturers of the motor to get it MSHA (Mine Safety Health Administration) approved. There is, it seems, no interest by Caterpillar to go any further than getting the new 3126 motor certified for outbye use. It would then be up to someone like DBT to get the engine with its final configuration for fitting to its machines then put it in for approval for face areas. This is going to require DBT or other manufacturers to source some sort of shrouding/insulating for the exhaust manifold to keep the temperature down to the magic 150 degrees celsius. There are some companies who have sent such materials into MSHA for assessment,” he said.
Following the trip, Vaccaneo concluded there would be a time delay in the introduction of electric engines and their effect on diesel particulate levels. The primary reasons for this were the slow turnover in replacing diesel vehicles at mines, and safety and approval issues.
“We will not support a watering down of the flame proofing and external engine temperatures for the sake of fitting in with the changing operating parameters of electronic motors,” Vaccaneo said.
Nelthorpe also doubted electronically controlled engines would have an immediate effect on exposure levels due to the slow turnover of vehicles. He predicted about half a dozen vehicles would be sold over the next two years, and thereafter the old engines would be slowly phased out. He also predicted that at the new engine’s Tier 2 rating, the effect on diesel particulate would not be dramatic.
“I haven’t analysed the results yet, but from what I have seen the engines are significantly cleaner than what we are used to. However, if you are looking at a reduction of 95% from a mechanical engine with the same power output, I don’t think you will see that with Tier 2 engines. At Tier 4 level you will attain that reduction and meet standards, unless of course the goal posts in tighter particulate regulations are raised in the interim, based on either more research or better technologies available,” Nelthorpe said.