One Question per Day, September 12, 2015
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The flow rate of acidic gas into the furnace is 1500 m3/h, while the air flow rate at the blower outlet is 2800 m3/h. The first-stage Claus unit is equipped with 8 m3 of catalyst. What is the space velocity? (Note: The relative density of the catalyst is 800 Kg/m3; it is assumed that 100% of the acidic gas contains hydrogen sulfide; the conversion rate in the reaction furnace is 80%)
This post was last edited by haiyangqh on 2015-9-11 at 16:17. I remember the formula, but I didn’t read the rest of the text
Volume space velocity = Raw material volume flow rate (20°C, m3.h-1) / Catalyst volume (m3) 187.5
This post was last edited by ylb913 on 2015-9-11 at 20:18. The question itself is flawed; firstly, you won’t be able to pass the material balance test. For 1500 standard cubic feet of 100% hydrogen sulfide, the air consumption should be around 1500*0.5/0.21 = 3570 standard cubic feet. The air velocity should be calculated using the volumetric flow rate under actual operating conditions, right?
The airspeed should be: (1500+2800)/8=537.5 h-1
80% of the hydrogen sulfide reacts according to the equation 2H2S + O2 → S (solid, recovered) + 2H2O; one-third of the remaining 20% reacts according to the equation 2H2S + 3O2 → 2SO2 + 2H2O. The volume change is calculated based on these reaction equations, and from this the flow rate into the reactor is determined, allowing the space velocity to be calculated. It’s too much trouble; I’ll just skip it
The teacher who mentioned the pressure gauge is right; there isn’t enough oxygen. Assuming 20% concentration, 750 units of oxygen are needed, but the actual amount available is 560. Well, let’s assume there is enough oxygen. Hydrogen sulfide is converted into water; the volume remains unchanged. Sulfur and SO2 are produced, and a total of 750 cubic units of oxygen are consumed. Thus, the final volume is 1500 + 2800 – 750 = 3550 cubic units. 3550/8 = 443.75 per hour. The relative density of the catalyst wasn’t taken into account here. .
This is the data for perfect operation, right?
It is calculated based on insufficient air supply and incomplete combustion of H2S.