| Time | Distilled Quantity per Hr (L/h) |
Vapour Condensed in Primary Condenser (kg/h) |
% Quantity Condensed in Primary Condenser (% of vapour) |
Vapour Condensed in Secondary Condenser (kg/h) |
Vapour Loss (kg/h) |
|---|---|---|---|---|---|
| Run CALCULATE to generate the table. | |||||
9B. Batch Utility Consumption & Cost Summary
Utility consumption is estimated from the calculated batch duties and operating conditions. Enter the applicable utility tariff and, where required, utility conversion assumptions for the batch study.
| Utility | Calculated Duty | Estimated Consumption / Batch | Tariff | Estimated Cost / Batch |
|---|---|---|---|---|
| Steam / Equivalent Steam | — | — | — | — |
| Cooling Water | — | — | — | — |
| Chilled Water | — | — | — | — |
| Total Utility Cost | — | |||
Direct steam consumption = Heating duty ÷ Steam latent heat.
For hot-water heating: Equivalent steam = Heat transferred by hot water ÷ Steam latent heat.
Heat transferred by hot water is taken from the calculated reactor heating duty for the batch.
Cooling-water consumption = Cooling duty ÷ (Water Cp × Cooling-water ΔT).
Chilled-water consumption = Chilled-water duty ÷ (Water Cp × Chilled-water ΔT).
Utility cost = Consumption × Applicable tariff.
Solvent mass evaporated (kg) = Distilled solvent volume (L) × Solvent density (kg/m³) ÷ 1000.
Utility cost per kg solvent evaporated = Total utility cost per batch ÷ Solvent mass evaporated per batch.
9C. Condenser Adequacy & Design Margin
This section compares calculated condenser duty with available design capacity. Utilization is based on required duty divided by design capacity; the remaining percentage represents available design margin.
| Parameter | Primary Condenser | Secondary Condenser |
|---|---|---|
| Required Heat Load (kcal/h) | — | — |
| Design Heat-Transfer Capacity (kcal/h) | — | — |
| Capacity Utilization (%) | — | — |
| Available Design Margin (%) | — | — |
| Thermal Adequacy | — | — |
Capacity utilization = Required heat load ÷ Design condenser capacity × 100.
Available design margin = (Design capacity − Required heat load) ÷ Design capacity × 100.
Interpretation: utilization ≤ 80% is shown as COMFORTABLE; >80% to 100% as REVIEW; >100% as INADEQUATE. These are screening indicators for the calculator and should be confirmed against the applicable project design basis.
1. Purpose of the study
This study combines reactor thermal performance, batch distillation vapour generation and dual-condenser adequacy. The selected solvent, reactor geometry, operating pressure, heating conditions and condenser utility conditions are used to estimate heat duty, vapour load, condenser split and overall recovery.
2. Boiling point from operating pressure
The solvent boiling temperature is estimated using the Antoine equation and the solvent-specific constants stored in the calculator.
P is the absolute operating pressure and A, B and C are the Antoine constants for the selected solvent. The resulting boiling temperature is used as the condensing-temperature basis.
3. Reactor heat-transfer area, U and LMTD
The reactor wetted geometry is used to estimate the effective heat-transfer surface. The temperature driving force is represented by the logarithmic mean temperature difference.
The reactor U is obtained from the reactor heat-transfer model using agitator, speed, vessel size, heating medium, circulation, solvent and reactor MOC inputs.
4. Vapour generation during distillation
The reactor heat duty is converted to vapour generation using the latent heat of the selected solvent.
Vapour load is expressed in kg/h. The simulation applies this rate to each time step and calculates the corresponding distilled quantity.
5. Condenser overall heat-transfer coefficient
The condenser U is calculated from condensation-side resistance, utility-side resistance, wall resistance and fouling resistance rather than using a fixed 650 kcal/h·m²·°C value.
Wall resistance is based on wall thickness and thermal conductivity. Utility-side heat-transfer coefficient changes with the selected utility and flow.
6. Design U basis
The calculated condenser coefficient is derated to 80% for design sizing.
The 80% design U is the coefficient used for condenser heat-transfer capacity and adequacy calculations.
7. Condenser LMTD
The primary and secondary condensers each have their own temperature driving force based on vapour temperature and utility inlet/outlet temperatures.
Section 9 reports reactor LMTD, primary condenser LMTD and secondary condenser LMTD separately.
8. Condenser heat-transfer capacity
For each condenser, available heat-transfer capacity is calculated from design U, installed area and LMTD.
The primary condenser is evaluated first. Vapour not condensed in the primary stage becomes the secondary condenser inlet load.
9. Vapour split and vapour loss
The loss is therefore the vapour remaining after both condenser stages have been considered.
10. Overall condenser recovery
Overall recovery represents the fraction of total generated vapour condensed by the primary and secondary condensers over the complete simulated batch.
Every simulation step is weighted by its actual duration, including the final partial step, so the complete batch is included.
11. Primary-to-secondary vapour line sizing
The vapour transfer line from the primary condenser vent to the secondary condenser is checked using the maximum simulated vapour flow entering the secondary condenser. The calculation uses the operating absolute pressure, vapour molecular weight and condensation temperature to determine vapour density.
Vapour density: ρ = P × MW / (R × T)
Volumetric flow: Qv = ṁ / ρ
Line velocity: V = Qv / A = 4Qv / (πD²)
Minimum required ID: Dmin = √[4Qv / (πVallow)]
For this calculator, the project screening criteria requested are <30 m/s for atmospheric service and <60 m/s for vacuum service. The entered line ID is checked against the selected criterion. These are screening/design-basis limits; final piping design should also verify pressure drop, compressibility, fittings, line length, supports and the applicable project/company piping standard. Published engineering guides show that vapour-line velocity criteria vary by service and pressure, so the project standard should govern the final selection. citeturn0search0turn0search1
12. Time-wise 9A report
The 9A table reports cumulative time, distilled quantity normalized to L/h, vapour condensed in the primary condenser, vapour condensed in the secondary condenser and vapour loss. This provides a direct engineering view of condenser performance as the batch progresses.
12. Engineering interpretation
A positive vapour-loss value indicates that the combined condenser capacity is insufficient for the generated vapour under the entered operating conditions. Condenser adequacy should be reviewed against actual geometry, utility flow, LMTD, design U and pressure-drop limitations.