Bisulfit Bisu lfite e Liqu Liquor or Produc Production tion (Calculations)
“
THOUGHT FOR THE DAY
I can't change the direction of the wind, but I can adjust my sails to always reach my destination.” – Jimmy Dean
TODAY:
Bisulfite Liquor Production Exercises
Bisulfite Liquor Production Slaker: CaO + H2O Ca(OH)2 MgO + H2O Mg(OH)2 Absorption Tower: Main Reactions: Ca(OH)2 + 2SO2 Ca(HSO3)2 Mg(OH)2 + 2SO2 Mg(HSO3)2 Side Reactions: Ca(OH)2 + SO3 CaSO4 + H2O Mg(OH)2 + SO3 MgSO4 + H2O H2O + SO3 H2SO4 SO4 + (1/2) O2 SO3
Bisulfite Liquor Production Gases from sulfur burner are passed through a cooler, an entrainment separator and then into an absorption tower. Milk of Lime or Slaked Lime – lime mixed with water - mixture of CaO, MgO and Inerts •
To determine if oxidation of SO2 to SO3 took place, the waste gases are compared with the cooled burner gases. If the O2 in the waste gases is less than the O2 in the cooled burner gas, oxidation took place.
Bisulfite Liquor Production The mixture of Ca and Mg bisulfitea, Ca and Mg sulfates, H2SO4, inerts and water make up the bisulfite liquor. Analysis of the bisulfite liquor is usually reported in terms of % SO2. %SO2 contains both free SO2 and present as bisulfites.
Example: 10% SO2 may mean 3% free SO 2 and the rest are present as bisulfites.
Bisulfite Liquor Production Waste Gas
Primary Air
BURNER
Pyrite or Raw S
BG
Cinder
COOLER
SLAKER
GAS ABSORBER
Water
Cooler Gas Bisulfite Liquor
Lime
Complete analysis of burner gas shows 5.71% SO 2, 9.51% O2, 82.58%N2 and 2.20% SO3. The burner gases are cooled and made to come into contact with milk of lime in an absorption tower. The dolomitic lime used is 82% CaO, 16% MgO, and 2% inerts. The bisulfite liquor produced contains 7.05% total SO 2 of which 1.15% is “free” and the rest 5.9% being present as bisulfites. An analysis of the dry waste gas shows that it contains only O2 and N2. Assuming no further oxidation of SO 2 to SO3 and formation of H2SO4 in the tower, calculate: (a) Wt of the bisulfite liquor (10,378 kgs) (b) Lime consumption per hour (494 kgs/ hr) (c) Wt of water used for slaking/ hr (8,801 kgs/ hr) Note: 200 kmoles/ hr of burner gas is charged to the cooler.
The roasting of iron pyrites analyzing 85% FeS 2 and 15% gangue utilizes 40% excess air (FeS2 to SO2) supplied at the rate 358 m 3/ hr at 23°C, 743 mmHg and 88% RH. A partial analysis of the cinder showed 25.92% FeS 2 and 17.83% gangue. Only 65% of the FeS2 gasified is converted to SO 2, and the rest to SO 3. The burner gases are cooled and charged to a converter together with slaked lime from a dolomitic lime containing 75% CaO, 25% MgO. If 850 kg/hr of bisulfite liquor are produced with no oxidation of SO2 to SO3 taking place. Assume all SO 2 is converted to bisulfite. Calculate: (a) kg/ hr of lime (33.724) (b) kg/ hr of water for slaking (704.77) (c) Complete analysis of the burner gas (5.35% SO2, 8.83% O2, 81.06% N2, 2.15% SO3 and 2.61% H2O)
Narayanan, K.V. & Lakshmikutty, B. (2006) Stoichiometry and Process Calculations. Delhi: Asoke K. Ghosh, Private Limited. Laurito, Evelyn R. (1994). Stoichiometry of Fuel Combustion and Related Process Industries. Quezon City: National Bookstore. Lewis, W.K. et al. (1954). Industrial Stoichiometry: Chemical Calculations of Manufacturing Processes. New York: McGraw-Hill. Williams, E.T. & Johnson, R.C. (1958). Stoichiometry for Chemical Engineers. New York: McGraw-Hill Book Company.