| Case | Gas Flow (m³/h) | Velocity (m/s) | EBRT (s) | Packing (mm) | Diameter (m) | Bed Height (m) | ΔP (kPa) | Liquid (L/min) |
|---|---|---|---|---|---|---|---|---|
| A | 12,000 | 1.8 | 2.0 | 38 | 1.535 | 3.600 | ~1.1 | 400 |
| B | 6,500 | 1.6 | 1.5 | 50 | 1.194 | 2.400 | ~0.4 | 217 |
| C | 20,000 | 2.2 | 2.5 | 25 | 1.620 | 5.500 | ~3.2 | 667 |
- Actual gas flow: for normal flow, Qact = Qn × (T/Tstd) × (Pstd/P).
- Area: A = Q / v, where Q is in m³/s and v is superficial velocity (m/s).
- Diameter: D = √(4A/π).
- Bed volume: V = Q × EBRT.
- Bed height: H = V / A.
- Liquid flow: L = Qact × (L/G factor).
- Packed-bed pressure drop (Ergun): ΔP/L = 150(1−ε)²/ε³ · μv/dp² + 1.75(1−ε)/ε³ · ρv²/dp.
- Enter your gas flow and select the proper unit type.
- Provide operating temperature and absolute pressure for conversions.
- Choose a target superficial velocity based on entrainment limits.
- Set EBRT to reflect removal needs and expected mass transfer.
- Input packing size, void fraction, and gas properties for ΔP.
- Set a liquid rate factor aligned to your chemistry and scaling.
- Review results, then export CSV or PDF for coordination.
1) Packed-Bed Scrubber Role in Construction Projects
Gas scrubbers are frequently specified on tunneling, coatings, wastewater, and industrial retrofit works where odor, acid gases, or solvent vapors must be reduced before discharge. A packed-bed unit provides large contact area by forcing gas through wetted packing. Preliminary sizing focuses on the shell diameter, packed height, liquid circulation rate, and an acceptable pressure drop for the fan system.
2) Gas Flow, Velocity, and Column Diameter
Diameter is driven mainly by the actual gas flow rate and the chosen superficial velocity. For many packed-bed services, designers start in the 1.0–2.5 m/s range to balance footprint and entrainment risk. At a fixed flow, lowering velocity increases cross-sectional area and can materially increase steel tonnage, access platforms, and duct sizes.
3) Contact Time and Packed Height
Removal performance is linked to mass transfer and reaction, so the empty-bed residence time (EBRT) is often selected as a first-pass proxy. Typical EBRT targets are commonly 1–3 seconds for many odor and soluble gas duties, while harder-to-treat streams may require higher contact time and improved chemistry. The calculator converts EBRT into a packed height estimate and then applies a safety factor for contingency.
4) Hydraulics, Packing, and Pressure Drop
Fan power and noise constraints make pressure drop a practical limiter. Packing size and void fraction strongly influence ΔP; smaller media generally raises resistance but may improve wetting and surface area. Many preliminary designs aim for moderate packed-zone losses, then confirm with vendor curves and allowance for demisters, distributors, and duct transitions.
5) Liquid Rate, Distribution, and Buildability
Liquid circulation supports absorption, neutralization, and solids management. Rule-of-thumb liquid-to-gas factors are used early, then refined using reagent demand, make-up water limits, and scaling potential. From a construction standpoint, provide access for packing installation, lifting beams, spray header maintenance, and corrosion-resistant materials in wet sections. Final equipment selection should confirm internals, nozzle loads, and platform clearances against site constraints.
1) What does “actual gas flow” mean in sizing?
Actual flow is the volumetric flow at the scrubber’s operating temperature and absolute pressure. If you enter normal flow, the calculator converts it using ideal-gas scaling to estimate the real flow inside the column.
2) How do I choose superficial gas velocity?
Start with 1.0–2.5 m/s for many packed-bed duties, then adjust for entrainment sensitivity, available footprint, and fan capability. Higher velocity reduces diameter but can raise mist carryover and pressure drop.
3) Is EBRT enough to guarantee removal efficiency?
No. EBRT is a practical first estimate for packed height, but true performance depends on chemistry, mass transfer, reaction kinetics, packing type, liquid distribution, and inlet concentration. Confirm with vendor data and process testing.
4) Why does packing size affect pressure drop so much?
Smaller packing increases flow resistance because gas must move through tighter pathways. The pressure-drop model scales strongly with packing diameter and void fraction, so ensure your packing assumptions match the intended internals.
5) What pressure drop range is reasonable?
Many projects target a moderate packed-zone pressure drop that the fan can handle with margin. If the calculator shows a high value, revisit velocity, packing size, and void fraction, then validate against vendor curves.
6) How should I set the liquid rate factor?
Use a conservative starting factor for early layouts, then refine based on reagent demand, absorption capacity, solids loading, and scaling control. Ensure the distribution system can deliver uniform wetting across the bed.
7) Can I use the outputs for final procurement drawings?
Use them for preliminary coordination only. Final design should include detailed hydraulics, materials, internals, demister selection, nozzle sizing, structural loads, and safety requirements, verified with a qualified vendor and engineer.