Overmod carnej1 This may not be as big an issue with industrial operators whose locomotives stay captive within their plant trackage.. Where I have the most interest is in the Class II use of reliable small high-speed engines to replace "cheap old GP7s" and the like as bottom-line cost-effective solutions for the size and nature of the trains they run. An interesting current thread in LocoNotes indicates that a couple of SW1000-size engines are going to have their frames lengthened, a pair of 750-hp [edited; was 900] Cat gensets installed, and the brake gear updated and modernized ... presumably for this type of service, and with the 'modularity' of the power such that loading and unloading issues due to engines having to be cut on and off to meet transient grades and other causes of train resistance will be effectively minimized. These are said to be dual-fuel capable C18s, probably (at 750hp) not very different from the 'small' engine in a PR43c. Does this engine need SCR, or could it use alternative technologies like EGR effectively -- there certainly seems to be room for the necessary equipment for non-DEF NOx reduction for two engines this size. Not sure I have seen a project quite like this before from one of the 'alternative locomotive' builders (the concentration seems to have been on repowers with larger high-speed engines, penny-pinching minimum-power gensets or battery hybrids, or 'environmental-centric' builds for use in air-quality-management districts perhaps without regard to actual operating flexibility as a required parameter.) I'll be watching out to see where this project goes, how successful it is, and whether it justifies its modification costs in service.
carnej1 This may not be as big an issue with industrial operators whose locomotives stay captive within their plant trackage..
Where I have the most interest is in the Class II use of reliable small high-speed engines to replace "cheap old GP7s" and the like as bottom-line cost-effective solutions for the size and nature of the trains they run. An interesting current thread in LocoNotes indicates that a couple of SW1000-size engines are going to have their frames lengthened, a pair of 750-hp [edited; was 900] Cat gensets installed, and the brake gear updated and modernized ... presumably for this type of service, and with the 'modularity' of the power such that loading and unloading issues due to engines having to be cut on and off to meet transient grades and other causes of train resistance will be effectively minimized.
These are said to be dual-fuel capable C18s, probably (at 750hp) not very different from the 'small' engine in a PR43c. Does this engine need SCR, or could it use alternative technologies like EGR effectively -- there certainly seems to be room for the necessary equipment for non-DEF NOx reduction for two engines this size.
Not sure I have seen a project quite like this before from one of the 'alternative locomotive' builders (the concentration seems to have been on repowers with larger high-speed engines, penny-pinching minimum-power gensets or battery hybrids, or 'environmental-centric' builds for use in air-quality-management districts perhaps without regard to actual operating flexibility as a required parameter.) I'll be watching out to see where this project goes, how successful it is, and whether it justifies its modification costs in service.
I don't have the time to post links but Caterpillar uses SCR across their Tier IV compliant engine product lines, the big exception being the new 1010 designed specifically for locomotive applications.
Other industries have accepted SCR as standard for Tier IV compliant engines and don't have the same operational issues with it that the railroad industry faces. That said, the experience with developing (I realize it wasn't "from scratch") the EGR system on the 1010 could give Cat an impetus to adopt it for other engine models. However, I doubt they would spend the money just to get more railroad business for smaller engines like the C18.
"I Often Dream of Trains"-From the Album of the Same Name by Robyn Hitchcock
carnej1Other industries have accepted SCR as standard for Tier IV compliant engines and don't have the same operational issues with it that the railroad industry faces. That said, the experience with developing (I realize it wasn't "from scratch") the EGR system on the 1010 could give Cat an impetus to adopt it for other engine models. However, I doubt they would spend the money just to get more railroad business for smaller engines like the C18.
Here's the thing: No doubt that Cat has good SCR implemented on anything used in a road vehicle (where packaging and operational considerations make EGR inferior to urea aftertreatment in a number of respects). Also no doubt that 'railroads' in general are taking what I think is fair to call a 'skinflint' line on any system that involves consumables where a 'fixed' system that avoids them can be used instead.
It was pointed out in an older reference that DPF consumption in locomotive-scale engines amounted to 3% or less of SFC, and the engine can be tuned for hotter exhaust when active NOx reduction is in play so it runs more efficiently as a heat engine. On the other hand, if Cat is serious about adapting the C18 in particular as a 'dual-power' or genset-locomotive engine of choice, that is where I would expect to see a 'modular EGR' solution at railroad packaging and weight scale. And I would be very surprised not to see it, whether or not the C18 is already qualified at Tier 4 final or better using existing SCR. (And runs better, more economically, and with lower coking or other EGR-related maintenance that way...)
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