How to mitigate acid corrosion from burning high sulfur oil?

cowdog

Affordable oily fuels, such as No. 6 fuel oil and tire pyrolysis oil, have high sulfur content.
Most sulfur will become sulfur dioxide in exhaust, but some will become sulfuric acid which is highly corrosive for metals.

How to mitigate this acid corrosion?

Can we mix the oil with something that produces an alkali when combusted?

I can think of soap (sodium stearate) which combust into baking soda (sodium bicarbonate). Soap is soluble in oil.

The resulting sodium sulfate is a solid, but will it deposit in combustion chamber and heat exchange surfaces?

Jamie Hall

No. If you burn high sulphur fuels, the only way you can keep the sulphur dioxide out of the atmosphere is to neutralize it in the stack gas. This is usually done with limestone dust, and the resulting slurry, while still hazardous, is at least manageable. Otherwise the sulphur dioxide will form sulphurous or sulphuic acid, if not in your stack, in the surrounding air.

Some industrial processes directly and deliberately condesne the sulphur dioxide as sulphuric acid and seel the product; it has value. This only works when sulphur dioxide is that major constituent of the stack gas, such as in smelting sulphide ores.

Interestingly, this is one of the first major air pollutants to have received significant attention -- and reduction.

The best solution for small operations is to use corrosion resistant materials or, if you don't worry about the air quality, just keep the stack gas hot enough to avoid condensation.

cowdog

Jamie Hall said:

The best solution for small operations is to use corrosion resistant materials or, if you don't worry about the air quality, just keep the stack gas hot enough to avoid condensation.

What if I want to use tire pyrolysis oil for car? The octane number of tire pyrolysis oil is 87, good for gasoline engines, but how to avoid condensation in engine and tail pipe? Can we use a dual-tank of gasoline and tire pyrolysis oil, use gasoline to get the engine hot, then switch to tire pyrolysis oil, and switch back to gasoline a moment before parking?

Jamie Hall

Since the viscosity of pyrolysis isn't even close to that of gasoline, and is unstable to boot...

You will have to retune the injectors (and probably high pressure pump) or the carburetor to use it.

If you're planning on using it in a fuel injected engine, your mixture numbers will be all over the map, even if it doesn't clog the injectors. In a carburetted engine you might get away with it some of the time, if it's a very simple carburetor. It will gum it up, but if there are no moving parts in there other than the float and needle valve it may work, at least for a while. I would not count on the octane rating being consistent; you may have detonation problems.

I doubt that you will be able to maintain the exhaust system entirely above condensation temperatures, unless you are contemplating an application which runs at a relatively high power at all times. In any case, I would use all stainless steel for the exhaust system. You will not, of course, be able to use catalytic converters.

I know of no jurisdiction where you could legally operate a motor vehicle on the road using it, except possibly for some classics for special use. Off road applications may be feasible.

cowdog

Jamie Hall said:

the viscosity of pyrolysis isn't even close to that of gasoline

Tire pyrolysis oil is different from biomass pyrolysis oil. Tire pyrolysis oil's viscosity is about the same with kerosene.

Jamie Hall said:

I know of no jurisdiction where you could legally operate a motor vehicle on the road using it, except possibly for some classics for special use. Off road applications may be feasible.

Rural America operates on a reduced set of laws compared to urban America.
Many rural counties don't inspect emissions at all (you can pass inspection even with check engine light on).

Jamie Hall said:

I doubt that you will be able to maintain the exhaust system entirely above condensation temperatures

Can we insulate the far ends of exhaust pipe with rockwool?

Jamie Hall

cowdog said:

Jamie Hall said:

the viscosity of pyrolysis isn't even close to that of gasoline

Tire pyrolysis oil is different from biomass pyrolysis oil. Tire pyrolysis oil's viscosity is about the same with kerosene.

Jamie Hall said:

I know of no jurisdiction where you could legally operate a motor vehicle on the road using it, except possibly for some classics for special use. Off road applications may be feasible.

Rural America operates on a reduced set of laws compared to urban America.
Many rural counties don't inspect emissions at all (you can pass inspection even with check engine light on).

Jamie Hall said:

I doubt that you will be able to maintain the exhaust system entirely above condensation temperatures

Can we insulate the far ends of exhaust pipe with rockwool?

Items 1 and 2 -- yes, I know that. It's not the same as gasoline, and the difference is enough to require recalibrating any jets or orifices. Item 2. I know that, too -- I live there. That does not relieve you or me or anyone else from at least trying to be vaguely responsible.
Item 3. Wrapping the pipe with rockwool would certainly help, though I'd probably do the whole length.

426hemi

Are we talking about burning it in boilers or in engines? We used to run #6 in both boilers and low speed diesels and corrosion wasn’t an issue in either. There is no way a modern high speed diesel can run heavy fuel oil as the injectors are way to sensitive, due to emissions regulations modern engines have tiny passages in the injectors and extremely delicate high pressure pumps. Even running a blend is likely to wipe out a $10,000 dollar injection system in a few hours. As far as older engines corrosion was never an issue the engines cylinders kits will wear out long before any corrosion occurs. Now maybe if we are talking about an engine that will sit for long periods of time without running you might have an issue. As far as boilers older ones were built with thicker metal and used fire brick lined combustion chambers, running a modern high efficiency boiler on heavy fuel oil is going to cause them to plug up with soot and ash and require frequent cleaning, most modern residential boilers are made of lousy thin materials and almost impossible to clean the slag out of without damaging so any corrosion issues are not a concern. They have small passages that will plug up quickly. We’re not talking about some soot that can be brushed out like with #2 but slag that requires chipping away. Just the act of trying to chip slag out of one is likely to damage/destroy it. Honestly I’ve never seen an exhaust stack rust out from the inside from burning heavy fuel oil even after 200,000 plus hours of run time over 80 plus years  but these stacks were made of heavy wall thickness steel pipe (probably 1/4 inch wall) not sheet metal. The soot/slag build up probably protects the steel from corrosion as it’s an oily substance. 

426hemi

Also to form sulfuric acid requires water and there isn’t any water in the exhaust stack as the temperatures are extremely high. Gasses are flowing out at a high rate of speed. The sulfuric acid gets formed in the atmosphere probably in rain clouds not inside the engine, boiler, or exhaust stack.