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Author Topic: electric trains  (Read 583 times)
Philip R
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« Reply #15 on: March 26, 2020, 12:19:59 PM »

Red diesel is used by some farmers for grain dryers firing. Pressure jet burners running on this are more fickle than those that use the lighter C2 domestic heating oil (kerosene).

I have seen and smelt diesel vans running on what I suspect to be red diesel. It has a higher sulphur content and therefore damages the engine oil, catalyst if fitted ND egr. The higher sulpur increases the smokiness of the exhaust, which is a giveaway too.

Taxing C2 kero will not go down well with the people off the gas grid out in the sticks.

Philip R
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Philip R
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« Reply #16 on: March 26, 2020, 12:25:37 PM »

Regen on DC is more difficult if there is no other load like another train.
Most of the DC traction substations have good old transformers with diode rectifiers.

With AC traction supplies , regen braking is easier. The volts on the line go up everytime it is applied.
Philip R
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Countrypaul
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« Reply #17 on: March 26, 2020, 02:41:23 PM »

There are 2 grades of red diesel, one is EN590 and is basicallay the same as normal road diesel only with a marker applied - this is also ULSD. The other is grade D red diesel that should only be used in static generators or boilers this can in theory have upto 1000mg/L (think its mg/L) sulphur. Pressure jet burners should tolerate either version of red. Many modern agricultural vehicles require EN590 diesel whether its red or white as such most red diesel supplied is to EN590. EN590 also contains about 7% biodiesel (maybe to increase lubricity since there is less sulphur present). Running these vehicles on class D will often invalidate the warantee etc. (John Deere certainly but others also I believe).

Diesel engines can run on biodiesel (though things like rubber seals may need replacing), and most IDI diesels can run on vegetable oil (seals may need replacing) without problems. Any engien running on Bio Veg Oil does smell different even with lowish amounts present.

The unscrupulus also often put parafin into the fuel tank as its much cheaper but the smell of these is quite obviously abnormal - and it totally illegall I believe (plus the lower lubrication can ruin the engine).
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Nickel2
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« Reply #18 on: March 26, 2020, 03:55:32 PM »

Where does gas-oil fit into the equation? A lot of the older gensets I helped load-testing had this filthy brown stinking gas oil that glugged when you pumped it. I was surprised to see the exhaust gasses were water-clear when the engines were hot and running at 100%. It always took a while to burn the soot out of the silencers if they were run on too low load.
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1.140kW mono south-facing at 49*
EpEver 4210A at 24v
Nearly dead 24V 400 Ah battery. (4x200Ah FLA)
EpEver STI1000-24-230 pure sine inverter
Of course it'll work. (It hasn't caught fire yet).
Philip R
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« Reply #19 on: March 26, 2020, 05:47:01 PM »

I remember when Aggreko come to site to set up the diesel powerred chillers for the outage. he said that gensets used at events like concerts came back all choked up with soot because they ran at next to zero load. Apparantly the fuel consumrtion at full spped no load is about 40% of full load. Hence why modern electric ships have diesel engines/ gas turbines that run in cascade, to improve fuel consumption.

Engines had to be put on load bank and progressively load raised till the soot blew out the exhaust, sometime incandescent.

Remember travelling back from ostend to dover on the ferry about 1990. there was a road tanker with hose discharging down into the engine spaces below the car deck. Out the pipe union was drippng a treacle like fuel oil. Interesting smell on the finger!!.
Gas oil comes in avariety of types.  However up on deck, the funnel smoked very little.
We used to use fuel oil in the auxillary boilers. A black treacle like oil that had to be heated to 70 deg C to burn it in a hamworthy rotary cup burner. The burner could generate a flame about 2.5 to 3 meters long. When set up, the stack barely smoked . when it was wrong, the black smoke would fall out the top of the chimney straight down to the ground and make a complete mess of everything.
The fuel was dispemsed with and converted to kerosene, like the gas turbines. Made everything easier to manage and maintain, albeit more costly for the fuel.

As for modern diesel freight train locos, not much smoke from them, just hot air out the exhaust. Not like the claggy smoke from older locos of the BR era. ( Mind you, no low sulphur fuel or very high pressure fuel injection back then.)

CP, thanks for the clarification of the different sulphur levels found in the Ribena coloured motion lotion.

Philip R
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Countrypaul
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« Reply #20 on: March 26, 2020, 05:56:16 PM »

Red Diesel had lots of names including: 35sec heating oil, farm oil, gas-oil, agricultural diesel, Off road diesel, tractor diesel - it probably even varies region to region (my view), but comes down to almost the same thing (D2 or EN590).

I thought the larger ships used Bunker oil (it probably has multiple names too) that needed heating to 70C+ before it could be used properly.

My understanding is that most CI engines need to run at some load to work efficiently, even diesel generators if left running without load coke up, and taxi's that are left to idle for long periods suffer also. The thicker the oil the more prone to carbon build up the engine is, so those using veg oil for example suffer more than those using Biodiesel.
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Philip R
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« Reply #21 on: March 26, 2020, 06:05:00 PM »

New rules from the international maritime organisation have come in this year. To reduce sulphur content of fuel oil for shipping. Hence big demand for lower sulphur fuel oil.
Apparantly one of the crudes from the UK north sea is used directly in some large ship engines because the crude is quite clean, low sulphur content  and does not need refinining for this duty.

Philip R
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