5 replies to this topic

[skylee8888]

Hi ppl,

I'm a 3rd year Chemical Engineering Student. I was told to design a sulphur burner/ furnace which takes the combustion process of a molten sulphur with air to produce sulphur dioxide in a sulphuric acid plant. It is done with excess air up to 10% and the molten sulphur is sprayed into the system with a sulphur gun/atomizer. The operating condition is to take place at 1000degree C at 1.6barg. Most of the sulphuric acid plant would suggest to implement this furnace as a horizontal cylindirical furnace equipment. Is there any books that provide steps/ ways to design such equipment as well the method to design the atomizer/ sulphur gun nozzle. Any books, patents or resources feedback will be helpful.

Thanks

Cheers.

[kkala]

Searcing for "sulphuric acid" in www.bookfinder.com you can trace quite a lot of books (but which are useful?). Adding "sulphur burner" to keywards in the search boox will return only two books, one of 1930 and another of ~1947 (mainly referring to Lurgi, specialist in pyrite processing). If "burning chamber" is added instead, no book is returned.
So subject may be proprietary with little material published in books. You had better not stop searching for information and general industrial conditions (in patents, magazines, etc), but after a point you may proceed through your own assumptions (this may be the purpose of the exercise, do not spend all available time searching data from literature).
For instance, I would think as follows, without having actual experience apart from having seen few units operating.
1. A sulfur burner can be similar to a fuel oil burner (materials can be different). Liquid sulphur has ~10 cP viscosity at (130-140 oC), fuel oil is heated to have 15-20 CP before introducing it to burners. Excess air for fuel oil is 10-15% (modern boilers). Maintaining constant temperature of approx 130-140 oC in liquid sulfur is necessary and should be controlled.
2. Atomizing medium should be compressed dry air (not steam, used in fuel oil), to avoid premature formation of H2SO4 at cold parts downstream (think of acidic dew point: there is abundance of SO2, so there must be no water vapor).
3. Chose a specific burner for viscous oils with desirable turnover (e.g 3:1) and assume maximum introductory pressure (e.g. 8 Barg) for atomization, according to its published operating guidelines. This (plus some margins for control valves, strainers and line ΔP) will specify the required head of sulfur feeding pump. Intermediate controls are rather complex for fuel oil boilers.
4. For ~45 MWth fuel oil boilers we install 2 burners (4 is better but more expensive); assume burners of lower capacity for liquid sulfur. Each of them can have a retractable pilot (lit at the start with fuel gas or LPG) and UV detectors checking the existence of flame continually.
5. Concerning the combustion chamber (radiant section):
5.1 Heat release (Heat produced per unit volume) and heat liberation (Heat produced per unit surface of wall absorbing heat, e.g. of tubes around the chamber) should be within limits for a satisfactory service life. But service life depends also on other factors. These limits differ from source to source. However you can conveniently specify radiant section volume and heating surface based on them.
5.2 You can go to W.H. McAdams' "Heat transmition" (chapter of radiative transfer, McGrawHill, 1954) for flame emissivities; also for mean beam lengths of SO2 (data published for want of something better, as noted), although modern versions must be published now (e.g. Sarofirm's Radiative heat transfer).
6. Specific comments on the above would help make situation clearer.

Edited by Art Montemayor, 24 February 2011 - 06:55 PM.

[kkala]

Following yesterday post, acceptable limits for fuel oil boilers' radiant section can be as follows:
Heat liberation = 600 kWth/m3 (based on fuel LHV)
Heat release = 450 kWth / m2 (based on fuel LHV), surface is "effective projected radiant surface" per ABMA, see http://books.google....surface&f=false.

[skylee8888]

Thanks kkala, I find your information gave me a good start to what I should be looking for and where to begin with.

1. However, is there any way to design the atomizer (sulphur gun burner)? or normally we just provide the specification for the vendor to do this?

2. How do we determine the design operating pressure of this piece of equipment (sulphur burner)?

[kkala]

1. However, is there any way to design the atomizer (sulphur gun burner)? or normally we just provide the specification for the vendor to do this?
2. How do we determine the design operating pressure of this piece of equipment (sulphur burner)?

I think all burner guns for fuels (and of course for liquid sulfur) is of proprietary design (unless you have developed your model). So you give the specification to the vendor. You can select a burner and imagine it "adopted" for liquid sulfur.
If this is difficult, typical values for fuel oil burners using air as atomizing medium can be as follows.
fuel oil pressure at burner inlet: 5 kg/cm2 g (for liquid sulfur adopt 6 kg/cm2 g, since combustion chamber has a pressure of 1.6-2.0 kg/cm2 (burners of higher or lower pressure are available in the market).
atomizing air pressure: 1.0 - 1.5 kg/cm2g over mentioned fuel oil pressure.
atomizing air consumption: 0.25 kg/kg of fuel oil
Note: pilots have capacity 15 - 20 thousand kcal/h and supply pressure of 0.2-0.35 kg/cm2 g

[skylee8888]

Thanks kkala for your information, your links and advices does give me some guidelines and they are very helpful to me.