“What size scrubber do I need?” is the first question in every inquiry we receive. The honest answer is a calculation, not a catalog page — but the calculation is simple enough to sanity-check yourself. Here is how we size a packed-bed spray tower, step by step.
Step 1: Tower Diameter from Airflow
Packed towers like a superficial gas velocity of roughly 1.5–2.5 m/s through the empty cross-section. Faster risks flooding and droplet carry-over; slower wastes vessel cost. So: divide airflow (in m³/s) by your chosen velocity to get the cross-sectional area, then convert to diameter.
Example: 20,000 m³/h = 5.56 m³/s. At 2 m/s the area is 2.78 m², which is a tower of about Ø1.9 m. That is why you will see Ø1,800–2,000 mm quoted for this duty across the industry.
Step 2: Packing Height from Removal Target
Removal efficiency depends on transfer units, and each 1.5–3 m packed stage of 38–50 mm pall rings typically delivers one to two transfer units for a soluble gas like HCl with caustic scrubbing liquid. In practice: one stage for 90%, two stages for 99%, three when the inlet is concentrated or the limit is strict. When in doubt, we run the absorption calculation rather than guessing.
Step 3: Liquid Rate and Sump
A liquid-to-gas ratio of 1–3 liters of recirculated liquid per m³ of gas covers most acid-fume duties. For our 20,000 m³/h example that is a 20–60 m³/h recirculation pump — small, but it must run whenever the fan does. Size the sump for at least 5 minutes of pump volume, and add automatic make-up and blow-down so the chemistry stays in range.
Step 4: Pressure Drop and the Fan
Budget 300–800 Pa per packed stage plus 100–200 Pa for the demister and entry losses. A two-stage tower therefore usually needs 1,000–1,800 Pa at the fan — which is why the fan is selected after the tower, never before.
What We Need from You
- Airflow (m³/h) and gas temperature
- Pollutant species and, if known, inlet concentration
- Required outlet limit or removal %
- Footprint and height limits at the installation point
Send those four numbers to jinhaofeng298@163.com or WhatsApp +86 186 1558 6932 and we will return tower dimensions, stage count, fan duty and a price — usually within one working day.