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A question about Diesel

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A question about Diesel
Post by Michae   » Mon May 29, 2017 6:41 pm

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I've seen a few posts in here that briefly touch on the subject of Diesel,but is it even possible to produce diesel without electricity? Forgive my ignorance,if that's the case but I thought to refine diesel fuel in the first place from petroleum,power was needed to run the refining process,which would draw attention of the unwanted kind to the refinery in question?
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Re: A question about Diesel
Post by Weird Harold   » Mon May 29, 2017 8:16 pm

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Michae wrote:I've seen a few posts in here that briefly touch on the subject of Diesel,but is it even possible to produce diesel without electricity? Forgive my ignorance,if that's the case but I thought to refine diesel fuel in the first place from petroleum,power was needed to run the refining process,which would draw attention of the unwanted kind to the refinery in question?


It is very easy to produce "Diesel Fuel" without electricity. Especially since Diesel engines will run on just about any flammable liquid; IIRC, the original, genuine, Diesel was designed to run on peanut oil(?)--some relatively common and abundant vegetable oil, anyway.

The problem with Diesel as far as Safehold is concerned is the distinctive exhaust emissions, not fuel production. Even that is a relatively small risk compared to electric motors and transmission lines (or the spark-gap ignition system of gasoline engines)
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Re: A question about Diesel
Post by Jonathan_S   » Tue May 30, 2017 3:14 pm

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Weird Harold wrote:
Michae wrote:I've seen a few posts in here that briefly touch on the subject of Diesel,but is it even possible to produce diesel without electricity? Forgive my ignorance,if that's the case but I thought to refine diesel fuel in the first place from petroleum,power was needed to run the refining process,which would draw attention of the unwanted kind to the refinery in question?


It is very easy to produce "Diesel Fuel" without electricity. Especially since Diesel engines will run on just about any flammable liquid; IIRC, the original, genuine, Diesel was designed to run on peanut oil(?)--some relatively common and abundant vegetable oil, anyway.

The problem with Diesel as far as Safehold is concerned is the distinctive exhaust emissions, not fuel production. Even that is a relatively small risk compared to electric motors and transmission lines (or the spark-gap ignition system of gasoline engines)
Thing get more complicated if you're trying to adjust the ratios of fuel out of a give source of crude oil (catalytic cracking and the like). But simple distillation requires essentially a way to warm up the oil to it's vapor point and a tall fractional distilling tower (where the various weights of oil vapor stratify and condense back to liquid and run out the appropriate drain into collection tanks.

Obviously you need some experimentation or knowledge to actually do this and know where to set the drain points - but none of it requires electricity. (Though obviously electrical thermostats to control oil temp, and various electronic sensors give you better feedback and control - but they're not mandatory)


That's why posters here like diesel withing the restrictions of Safehold. You can build a supply and use chain from drilling, transport, distillation, transport, and consumption in a diesel engine all without requiring any electricity. (Though modern day diesel engines do use lots of electronic sensors, and often glow plugs and fuel warmers to better cope with cold starts. But non of that is strictly necessary - even though it makes things more user friendly)
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Re: A question about Diesel
Post by WeberFan   » Tue May 30, 2017 6:47 pm

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Now you're getting into MY business...

Not only is it possible to "produce" diesel (to refine it from crude oil), but it's done every day. Electricity is used, yes. But really only to run the control systems that enable refiners to optimize the process - to run the equipment as closely as possible to its theoretical operating limits. The underlying distillation process does not require any electricity at all. In fact, the control systems could be purely pneumatic or even manual.

To distill diesel from crude oil, you really need nothing more than a source of crude, a source of heat, and (as another said), a distillation column (a hollow tower with perforated "trays" at the levels where you want to draw off the various product streams. You'll also need a source of heat at the bottom of the column to keep the crude oil hot (steam is commonly used).

Essentially, you heat the crude oil to its boiling point or even higher (but obviously NOT to its flash point), then pump it into the bottom of the distillation column. If you can do this in an air-free environment, all the better and you can run the process even more efficiently. Vapors will boil off the tower and will flow toward the top, cooling as they do. The pressure will be highest at the bottom, and will get progressively lower as the vapor flows up the column. At different points in the column where you have installed the perforated trays, vapor will flow through the perforations, and some will condense due to the lower temperatures at that level. If you put a side draw pipe at this level, you can draw off the condensed material at that point. Materials with higher molecular weights can be drawn off at lower levels in the column, and materials with lighter molecular weights at the higher levels. Strictly speaking, what's left at the top is pure vapors, which can be condensed in a heat exchanger and reinjected at the top of the column to flow back down again and help you control the temperature profile in the column.

It sounds pretty complicated, but it's reall just "making moonshine."

And every day, refiners do this on an industrial scale. At one refinery I'm familiar with, the Crude Distillation Unit (which carries out the process I just described) processes 150,000 barrels (6.3 Million gallons) per day... 24 hours per day... Every day... for up to 5 years at a time... That's 4,375 gallons per MINUTE.

And one last oh-by-the-way. I mentioned "air-free" environment. This is commonly done in a refining environment by flooding the piping and the equipment with superheated steam to drive out the air. No air means no fire and no explosions in the equipment.
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Re: A question about Diesel
Post by saber964   » Tue May 30, 2017 7:01 pm

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IIRC they were refining oil into kerosene and other products in the 1850-60's so the technology is viable and doable.

How much refining is needed depends on the grade of the crude oil.

IIRC heavy crude oil contains the least amount of light distillate like gasoline and kerosene like around 10-20% before it's cracked to break the long carbon chains to get more distillate out.
What's known as light sweet crude oil contains the greatest amount of distillate which can be as high as 80% distillate.
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Re: A question about Diesel
Post by Louis R   » Tue May 30, 2017 10:45 pm

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Early 1850s, so well before even electric pumps were generally available. And those are easily replaced with steam-driven and/or pneumatic equipment.

saber964 wrote:IIRC they were refining oil into kerosene and other products in the 1850-60's so the technology is viable and doable.

How much refining is needed depends on the grade of the crude oil.

IIRC heavy crude oil contains the least amount of light distillate like gasoline and kerosene like around 10-20% before it's cracked to break the long carbon chains to get more distillate out.
What's known as light sweet crude oil contains the greatest amount of distillate which can be as high as 80% distillate.
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Re: A question about Diesel
Post by Hildum   » Tue May 30, 2017 10:57 pm

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Getting the appropriate distillate is no problem, and diesel engines can run on a lot of different fuels. How you would start a diesel is open to question, however. I suppose depending on the application you might be able to use steam or compressed air.
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Re: A question about Diesel
Post by Weird Harold   » Wed May 31, 2017 3:50 am

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Hildum wrote:Getting the appropriate distillate is no problem, and diesel engines can run on a lot of different fuels. How you would start a diesel is open to question, however. I suppose depending on the application you might be able to use steam or compressed air.


A lot of Diesel engines up through WWII started with compressed air. (including most WWII submarines) German aircraft Diesels started with a manually-wound flywheel. (You can see the winding in many WWII documentaries.)

A lot of youtubers start old Diesels by manually spinning the flywheel or drive-pulley. Of course, there's always the finger-flick used to start model aircraft engines when I was a kid -- those small two-stroke Diesels didn't have much compression to overcome in absolute terms.
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Re: A question about Diesel
Post by AirTech   » Wed May 31, 2017 7:27 am

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Weird Harold wrote:
A lot of Diesel engines up through WWII started with compressed air. (including most WWII submarines) German aircraft Diesels started with a manually-wound flywheel. (You can see the winding in many WWII documentaries.)

A lot of youtubers start old Diesels by manually spinning the flywheel or drive-pulley. Of course, there's always the finger-flick used to start model aircraft engines when I was a kid -- those small two-stroke Diesels didn't have much compression to overcome in absolute terms.


Spring starters are also common on small diesel engines (up to about 200kW or a small truck engine) and inertia starters are also possible for larger engines (using a crank to spin a flywheel and then using the flywheel to start the engine, a number of aero-engines used this (both diesel and gasoline) during WWII.
As for electricity free refining - I worked on a refinery where no electricity was used in the plant except for lighting and start-up pumps in the mid 1980's. Not just possible but you can get to 95% of the rated capacity of the plant with minimal controls (the remaining 5 to 10% is where the more complex control systems come in to improve yield (yes, you can get to over 100% of rated capacity - 120% is common but a hairy operational state)).
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Re: A question about Diesel
Post by WeberFan   » Thu Jun 01, 2017 11:48 am

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saber964 wrote:IIRC they were refining oil into kerosene and other products in the 1850-60's so the technology is viable and doable.

How much refining is needed depends on the grade of the crude oil.

IIRC heavy crude oil contains the least amount of light distillate like gasoline and kerosene like around 10-20% before it's cracked to break the long carbon chains to get more distillate out.
What's known as light sweet crude oil contains the greatest amount of distillate which can be as high as 80% distillate.

Not a hard and fast rule... Every reservoir produces crude with different characteristics. Some is "heavier" meaning more hydrocarbons with longer carbon chains in the molecules. Some is generally "lighter" meaning more hydrocarbons with shorter carbon chains. A "bucket of crude oil" contains a hodgepodge of hydrocarbon molecules with different lengths of carbon chains.

Whether crude is "sweet" or "sour" is irrelevant to the lengths of the carbon chains. This refers to the sulfur content of the crude (often in the form of hydrogen sulfide or H2S - which is toxic). In days gone by, folks on production or drilling rigs would "taste" the crude... If it tasted sweeter, (meaning less sulfur) then it was "sweet crude." If it tasted more sour, (meaning more sulfur) then it was "sour crude."

And you don't necessarily need to "crack" (meaning break) the hydrocarbon molecules into smaller ones when you refine if you accept that you'll have a less than optimum product mix. You could distill a bucket of crude and just draw off the "diesel" cuts, then use the rest (the heavier hydrocarbons that didn't vaporize in your distillation column) for road making (mixing heavy oil products with sand or stone dust actually makes a pretty decent road surface), and use the "light ends" for either fuel gas (C1 methane to perhaps C4 Butane), or for light distillates / solvents (C5 and greater up to your diesel range which is around C12 to C20 hydrocarbons). As a point of comparison, "gasoline" is in the C4 to C12 range - shorter (lighter) hydrocarbon molecules that are a bit more volatile.
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