SO2 removal from gases 1

[pabasolo]

We are working in the design of a lead recycling plant in uruguay (from scrap batteries).
To design the gas treatment operations, we are facing some difficulties regarding SO2 removal.
As using NaOH is proving too expensive, we have been offered a dry sistem, by injection of lime (CaO? Ca(OH)2?) to the gases, and then remove them in cyclone or filter (which would be there anyway).
How do we calculate lime consumption?
To what extent should we consider CO2 and CO competing?
What is the particulate size of products of reaction (CaSO4? etc)?
Can anyone send some process description?
Thanks,
Pablo

 

[9741411]

Very common to use dry Ca(OH)2 upstream of a baghouse for SO2 removal. Gas temp should be as low as possible (325F?)without causing corrosion and material handling problems with ash.

Expect to use a lot of lime - suggest NSR= 4-6 to get 75% reduction.

 

[MortenA]

Maybe its over the top but Topsoe has a process for converting so2 to sulphuric acid: check

http://www.topsoe.dk

This is a link to a brochure on the topic:

http://www.topsoe.dk/files/Cat - HT VK brochure.pdf

Best Regards

Morten

 

[25362]

Sulphuric acid production from SO[sub]2[/sub] laden flue gases is a matter of economics: investment, cost of plant operation, concentration of SOx in the flues, and, of course, possibility of marketing the acid.

pabasolo's idea of using a dry throwaway system seems right. Although it has fewer corrosion problems, less scaling difficulties and it appears to be easier in handling and disposal of the waste product, combination wet-dry, or wet lime systems are also in use. Either CaO or limestone (mainly CaCO[sub]3[/sub]) could be used. NaCO[sub]3[/sub]H or Na[sub]2[/sub]CO[sub]3[/sub] are more effective but more expensive.

9741411 is absolutely right in saying you need much more CaO than stoichiometrically estimated. This is due, in particular, to the fact that gas-solid reactions are not so efficient and depend on the surface area of contact between both reacting phases. The size of the collected particles also depend on the size of the ground neutralizer used.

CO or CO[sub]2[/sub] do not compete much at the prevailing conditions with lime or limestone; they would, however, with NaOH wet systems, because of the higher pH.

Particle collection devices are often shake-deflate parallel bag houses, or of pulse-jet design, but can also be ESP.

Con augurios de exito.

ESP: Electrostatic precipitators.

 

[pabasolo]

Thanks to all
You have been extremely helpful!
bye

 

[pkuziw]

There is a lot of good information about flue gas desulfurization at

http://www.lime.org/ENV02/ENV802.htm

Peter