Calculator
Fill in your operating data and target moisture. Results will appear above this form after submission.
Example data table
Illustrative only; adjust to your project basis.| Case | Flow (MMSCFD) | Pressure (bar) | Temp (°C) | Inlet moisture | Outlet target | Cycle (h) | Capacity (kg/kg) |
|---|---|---|---|---|---|---|---|
| A | 50 | 60 | 35 | 120 mg/m³ | 20 mg/m³ | 12 | 0.16 |
| B | 20 | 35 | 25 | 8 lb/MMscf | 3 lb/MMscf | 8 | 0.12 |
| C | 100 | 80 | 45 | 200 mg/m³ | 10 mg/m³ | 16 | 0.18 |
Formula used
- Moisture conversion: 1 lb/MMscf ≈ 16.02 mg/m³ (standard basis).
- Standard flow: 1 MMSCFD = 28,316.8466 m³/day (standard).
- Water removed: \(\dot m_{H2O} = (C_{in}-C_{out})\,Q_{std}\)
- Cycle loading: \(m_{cycle}=\dot m_{H2O,hr}\,t_{cycle}\)
- Media required: \(m_{media}= m_{cycle}/(Cap\cdot U)\cdot SF\)
- Bed volume: \(V_{bed}= m_{media}/\rho_{bulk}\)
- Actual flow (ideal scaling): \(Q_{act}=Q_{std}\,(T/T_{std})\,(P_{std}/P)\)
- Diameter: \(A=Q_{act}/v_{max}\), \(D=\sqrt{4A/\pi}\)
This tool sizes the adsorption bed by water balance and working capacity. It does not model pressure drop, heat duty, switching valves, or regeneration gas requirements.
How to use this calculator
- Enter standard gas flow, operating pressure, and temperature.
- Provide inlet and outlet moisture using your preferred units.
- Set media working capacity, utilization, and bulk density from datasheets.
- Choose cycle time and a reasonable superficial velocity limit.
- Apply a safety factor for uncertainty and expected performance margin.
- Click Calculate Sizing to see results above the form.
- Use the CSV/PDF buttons to export the last calculated case.
Feed Conditions and Moisture Basis
Accurate sizing starts with a consistent moisture basis. Convert dew point or water content to a standard concentration and align it with the project’s standard conditions. Operating pressure changes actual volumetric flow, but the water removed is set by standard flow and the inlet-to-outlet difference. Inlet values can range 50–250 mg/m³, while pipeline targets are below 10–30 mg/m³ depending on spec and hydrate risk.
Water Removal Rate and Cycle Loading
The calculator converts MMSCFD to standard m³/h and multiplies by the inlet-to-outlet concentration difference to estimate water removal rate. Cycle loading is the hourly removal rate multiplied by adsorption time per bed. Shorter cycles reduce bed mass but increase switching frequency and valve wear. Longer cycles increase bed inventory and vessel size. For a first-pass design, 8–16 hours per bed is common, then refined with regeneration constraints and site operability.
Adsorbent Capacity, Utilization, and Safety Factor
Working capacity depends on adsorbent type, inlet temperature, and regeneration effectiveness. Use vendor curves when available; otherwise treat 0.10–0.20 kg water per kg media as a screening range for molecular sieves under typical conditions. Utilization accounts for mass transfer zone and aging; 0.65–0.85 is a practical planning window. Safety factor covers uncertainty in feed variability, measurement error, and performance degradation; 1.10–1.30 is frequently applied in early engineering.
Vessel Hydraulics and Superficial Velocity
Diameter is driven by actual flow at operating pressure and temperature divided by an allowable superficial velocity. Lower velocity reduces pressure drop and attrition, but increases vessel diameter and cost. A screening limit of 0.10–0.25 m/s is often used for packed adsorption beds, then checked with detailed pressure-drop correlations and distributor design. The calculator reports cross-sectional area and equivalent diameter to help compare alternatives and confirm fabrication feasibility.
Regeneration Implications and Operating Margins
Regeneration requirements can dominate operating cost. Higher water loading increases heating duty and regeneration gas or purge demand. If the site uses a dedicated heater and cooler, verify that the selected cycle time matches available duty, cooldown time, and changeover sequence. Include margin for seasonal temperature shifts and upset conditions, such as compressor trips that raise inlet moisture. After screening, validate the design with vendor consultation, pressure-drop checks, and a heat-and-material balance.
FAQs
1) What inputs most affect the bed mass?
Gas flow, inlet-to-outlet moisture difference, cycle time, and working capacity drive required media mass. Utilization and safety factor adjust the result for real-world performance and uncertainty.
2) How do I choose working capacity?
Prefer vendor isotherm and dynamic test data for your gas composition. For early screening, use conservative values and increase safety factor, then update once regeneration temperature, purge rate, and outlet spec are finalized.
3) Does pressure change the water removal rate?
At a fixed standard flow, pressure mainly affects actual volumetric flow and therefore vessel diameter. The water removed is governed by the standard flow basis and the specified moisture reduction.
4) Why is superficial velocity limited?
High velocity increases pressure drop, maldistribution risk, and adsorbent attrition. Limiting velocity helps maintain stable mass transfer and protects internals, but may increase vessel diameter and capital cost.
5) Can this replace a vendor design?
No. It is a screening calculator for preliminary sizing. Final design should include pressure-drop modeling, distributor design, regeneration heat balance, switching sequence, and adsorbent selection with supplier review.
6) How should I interpret the number of beds?
Two beds support adsorption and regeneration cycling in many plants, but reliability, turnaround strategy, and turndown often justify three or more. Use the calculator results per bed, then evaluate cycle scheduling and redundancy.