Scrubbing out SO2   




 

MEMORANDUM

 


 

To: AIR QUALITY CONSULTANTS

From:

 John Sliwinski

   

 OSB Lab

     
Re: Scrubbing Out Sulphur Dioxide 

Date:

 02.09.12

Re: Laboratory Tests    



The attached Comparisons of Chromatograms illustrate the effect of Sodium Carbonate traps on scrubbing out SO2 and recovering VOCs. Sulphur Dioxide is removed chemically by reacting with Na2CO3 to form stable salts Na2SO3 and NA2SO4 depending on presence of air. Cold Na2SO3 traps do not absorb low boiling VOCs but do condense high boiling VOCs above Toluene b.p. Experiments have been carried out using odourless mineral spirits CAS No. 64742-48-9 b.p. 176-204C and Naphthalene b.p. 218C which show that Na2CO3 traps do not condense VOCs when heated at 120C or greater but still react with SO2 to remove it effectively.

 

Initial tests were carried out using a sample from a source exhausting a coal-fired combustion system. The sample was split and one portion was transferred through a cold (room temperature) Na2CO3 trap. The transferred sample, the heated (desorbed) trap and the unaltered split sample were all analyzed (00109c-21).

 

RUN

OBSERVATIONS

1NOV1312

The unaltered split sample shows large amount of SO2 and complete range of VOCs for reference.

1NOV1307

The cold trap transferred split sample shows complete elimination of SO2, good recovery of low boiling VOCs but a substantial loss of high boiling VOCs including Naphthalene.

1NOV 1309

The thermally desorbed Na2CO3 trap shows that SO2 is not released but all condensed semi-VOCs are recovered from the cold trap. Even Dibenzofuran is released upon heating.

 

Additional tests were carried out to determine how SO2 and VOCs behaved while being transferred through a heated Na2CO3 trap- at 120C. A 50ppm Scott SO2 gas cylinder was used as the source of Sulphur Dioxide, and a standard Tedlar gas bag was prepared with Naphthalene dissolved in odourless mineral spirits. Samples were analyzed under different conditions using C analytical tubes (01043b).

 

RUN

OBSERVATIONS

2FEB0503

200mL SO2 gas through trap at 120C. Sulphur Dioxide was removed.

2FEB0505

5mL SO2 gas spiked without trap. Sulphur Dioxide recovered.

2FEB0506

100mL SO2 gas spiked without trap. Sulphur Dioxide recovered.

2FEB0507

300mL SO2 gas spiked without trap. Sulphur Dioxide recovered.

2FEB0508

250L standard spiked without trap is recovered. Sulphur Dioxide is a carryover contaminant from previous run.

2FEB0509

1mL standard and 300mL SO2 gas spiked through trap at 120C. Sulphur Dioxide was removed but standard was recovered.

2FEB0510

4mL standard and 400mL SO2 gas spiked through trap at 120C. Sulphur Dioxide was removed but standard was recovered. Note 1-Tetradecene from high mineral spirits injection.

 

 

TEST RESULTS

 

RUN

TRAP C

SULPHUR

DIOXIDE

MINERAL

SPIRITS

NAPHTHALENE

 

 

g

Response Area

g

Response Area

g

Response Area

0503

120

26.58

9.03

0505

None

0.665

38.8

0506

None

13.29

543.4

0507

None

39.87

2193

0508

None

0

142

3.235

496.3

0.094

5.93

0509

120

39.87

66.5

12.94

2443

0.374

24.8

0510

120

53.16

83.1

51.76

5195

1.497

134.2

 

 

The data presented above is demonstrative in nature. Concentrations were selected to cover a broad range challenge not necessarily within the operating limits of the MSD. The smaller injection Naphthalene was used to monitor detection sensitivity.

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