Temperature & concentration disturbance changes in sulfuric acid vapor pressure. A schematic diagram is shown for absorption of SO3 gas into sulfuric acid.
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| Sulfuric acid plant: Absorption tower |
At a constant flow rate of sulfuric acid & SO3 gas, a controlled parameter of absorption process is temperature & concentration of sulfuric acid.
Now, look at the rate constant equation of absorption process.
H2SO4 → SO3 + H2O
Equilibrium Rate constant Kp = (P SO3 X P H2O) / P H2SO4
Now, look at the rate constant equation of absorption process.
H2SO4 → SO3 + H2O
Equilibrium Rate constant Kp = (P SO3 X P H2O) / P H2SO4
From this equation, we can understand
Kp > 1, No further absorption of SO3 gas
Kp < 1, Absorption can take place
Kp > 1, No further absorption of SO3 gas
Kp < 1, Absorption can take place
Now, because the constant flow rate of acid & gas, temperature & concentration of acid change the value of equilibrium rate constant Kp. We can say that Kp indicates the absorptive capacity of sulfuric acid for SO3 gas.
At higher concentration & temperature Kp will increase, decrease the absorptive capacity of sulfuric acid leads to stack gas emission in the sulfuric acid plant.
During absorption operation, the sulfuric acid temperature in tower bottom outlet leads to change its properties than the top area of the tower. SO3 gas is first getting in contact with tower bottom portion of acid. So acid temperature in tower bottom portion is a significant factor of SO3 absorption.
Controlling acid tower outlet temperature will give us significant benefits in operation & metallurgical aspects of the tower.
At higher concentration & temperature Kp will increase, decrease the absorptive capacity of sulfuric acid leads to stack gas emission in the sulfuric acid plant.
During absorption operation, the sulfuric acid temperature in tower bottom outlet leads to change its properties than the top area of the tower. SO3 gas is first getting in contact with tower bottom portion of acid. So acid temperature in tower bottom portion is a significant factor of SO3 absorption.
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