6 replies to this topic

[jonol92]

Morning,

 

Just a quick practical based question:

 

For dissolving 25 kg of urea prills into a ~90 litres of room temperature water (fairly warm environment) can anyone offer any guidance on how much agitation will be needed to completely dissolve the urea?  

 

I know the solubility of urea is such that this didn't ought to be too difficult but i'm not practically experienced enough to know how much agitation may be required and whether it will need to be continuous for the urea to remain dissolved?

If much agitation is needed, can anyone suggest a method most suitable? e.g. would hand stirring with a large pole be sufficient?

 

Cheers,

Jon

 

[Ming Hooi]

If dissolution time is not a factor, yes stirring with a large pole can eventually be sufficient.

[jonol92]

It's not a massive factor so thank you i'll probably go with that method.

 

Though from what i understand the longer the urea is present in solution the further it will hydrolyse, which increases the likelihood of scaling in the spray nozzles (im mixing the urea with mains water).

 

But as long as we're not talking several hours of mixing i think there shouldn't be a problem.

[Ming Hooi]

Please correct me if I'm wrong. I think you are in the wood composite industry and plan to spray urea solution at your continuous line to lower the formaldehyde emission. Be assured, such method is very normal.

 

If yes, please let me know. I have very long experience in such applications.

[jonol92]

Im on a placement at a chicken litter fuelled power station.  We plan on trialling spraying urea solution into the furnace to reduce NOx emissions.  

Quite similar to your experience i imagine, many concepts may be quite similar to the applications you're familiar with?

 

We have an existing water spraying system, I've just been struggling a little developing a practical solution to deliver the correct concentration of urea solution to the existing setup.

 

Thanks again for your response!

[Ming Hooi]

Using urea to reduce NOx emission from a furnace is something new to me.

 

About the concentration and feeding rate of urea solution, I would imagine that you will have to go to its stoichiometry to determine the ratio of urea / NOx, if not from the literature.

 

Sorry I can't help further. I have been looking up for an old document in my PC that describes very thoroughly the properties and characteristics of urea, but I still haven't found it. Will send to you when I do find it.

[jonol92]

I found a source that suggested a molar ratio of ammonia to NO of 1.5:1 (urea breaking down to form 2 ammonias at the right temperature) so i've worked with that and we'll see if its an effective concentration...

 

Unfortunately its dependant on delivery to the right areas of the boiler at the correct temperature for a sufficient amount of time so only the trial can really say if this will be practically effective.

 

Thank you very much, please do send it if you find it, i appreciate your input all the same