Sciencemadness Discussion Board

Sulfur burner for Sulfur Dioxide generation

Σldritch - 7-8-2020 at 01:04

I have had great success building a sulfur burner for the large scale production of sulfuric acid. There has been some previous attempts at burning sulfur for Sulfur Dioxide most use a aspirator to pull in the generated Sulfur Dioxide. I have instead built positive pressure system where the sulfur candle is keept at, you guessed it, positive pressure and not athmospheric meaning the produced Sulfur Dioxide will be pushed through the collection system. In general i think these are the merits and demerits of the two methods:

Pull (aspirator)
+ allows for very simple sulfur burner
- requires scrubbing system
- most people's aspirator pumps can not do long operation (though i believe that is due to bad ebay pumps being used, fountain pumps would be better)

Push (aquarium aerator)
+ No scrubbing or pulling acid through your pump
+ Cheap pumps designed for long operation available
- Complex sulfur burner

My design for a pushing sulfur burner consists of a steel bucket with air tight lid with two holes drilled in it. One above the other at the appropriate size for brass water hose adapters to be brazed to the bucket. These provide a simple, moderately corrsion resistant, airtight seal. Air is pumped in by water hose adapted for the aquarium aerator with PVC tubing.

To keep the lid on the bucket a weight will be needed proportional to the area of your bucket lid and the pressure you want the output to be at. If you want to bubble the output through water there is a very simple solution. Simply use wider water container than the lid of the bucket you use and you will always be able to bubble through the water in the container as long as your pump can handle the pressure and you do not lose too much pressure to leaks. To compensate for that some additional weight may be needed, i recommend concrete slabs for a nice flat surface to place the water container on.

The sulfur candle is very simple, just sulfur in a jar with a piece of rolled paper napkin stuck through it.

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Belowzero - 7-8-2020 at 01:37

Do you have any idea how much pressure your aquarium pump can apply to the system ?
I am currently working on a similar project and trying to figure out what pump best suits my needs.
Also have you done any measurements already?

Σldritch - 7-8-2020 at 01:56

My pump is up to 2 m water and 400l/h flow rate. I decided to buy one with high flowrate to maintain pressure with some leaks. I could probably get away with a lower flowrate since my system sems pretty air tight but i do not know how yours will act in that regard. What measurements are you interested in?

Belowzero - 7-8-2020 at 03:10

It seems I misunderstood , how are you generating positive pressure using a water pump ?

I am interested in the absorption rate and if you have any estimates of efficiency of the system.

Also as far as I understand the reaction of SO2 with water leads mostly to H2SO3, at least under normal conditions.

[Edited on 7-8-2020 by Belowzero]

Σldritch - 7-8-2020 at 04:44

Ah, im not using a water pump im using a aquarium aerator pump. I pump air into the bucket with the sulfur candle in it and then the Sulfur Dioxide and unconsumed air is forced out of the bucket through water. As for absorbtion efficiency i would say it is very (suprisingly) good. I burned maybe 250 g sulfur and pumped the gas formed into about 100 g Ferrous Sulfate Heptahydrate dissolved in 20 L water. When i used mineral wool as diffuser barely any smell of Sulfur Dioxide could be detected. It was evident on the solution that Sulfur Dioxide was being absorbed because the solution went from colorless to orange when it was actively absorbing Sulfur Dioxide. When it was aerated the color went back to light yellow. Of course this could be because Sulfur Dioxide went out of solution but it is so smelly i thnk i would notice. Also i believe the equilibrium is toward Sulfur Dioxide not Sulfurous acid in aqeous solution but if a metal is present a complex may form increasing solubility in addition to oxidation to non-volatile Sulfuric acid.

macckone - 7-8-2020 at 21:01

combined with a tube furnace filled with vanadium pentoxide catalyst on an appropriate substrate this would probably be even more effective. But then you would need to absorb the sulfur trioxide into sulfuric acid.

Alkoholvergiftung - 7-8-2020 at 23:50

Or if he doesnt have sulfuric acid he can burn an mix of sulfor and nitrate 12% nitrate. The NOx will form the trioxid the same way as the early lead chambers.