Flash Drum Designer

Flash Drum Designer is not a process simulator. It does not run flash calculations, heat balances, or thermodynamic separation modeling.

It is a preliminary mechanical sizing tool for horizontal and vertical knockout drums. Run your process in a simulator such as Aspen Plus, take the vapor and liquid outlet stream results (mass flow rates and densities), add design parameters such as residence time and K-factor, and this program estimates the drum diameter and length/height to build.

Aspen Plus can model a FLASH2 separator, but it does not size the vessel. Flash Drum Designer fills that gap using standard Souders-Brown and liquid-holdup correlations.

Quick Start (Windows)

1. Open the Releases tab on GitHub.
2. Download FlashDrumDesigner.exe from the latest release.
3. Double-click the executable to launch the desktop app.
4. Enter outlet stream data from your simulation (or click Load Example to try a sample case).
5. Click Calculate. A PDF sizing report is saved automatically in the same folder as the EXE.

No Python installation is required when using the packaged executable.

What This Tool Does

• Accepts outlet vapor and liquid mass flow rates and densities from your converged simulation
• Sizes the drum using Souders-Brown vapor disengagement and liquid holdup for a user-specified residence time
• Supports horizontal and vertical orientation
• Looks up GPSA pressure-based K-factors (or accepts a manual K-factor)
• Applies GPSA service corrections (standard, glycol/amine, compressor suction), demister adjustment, and pressure applicability rules
• Assumes a fixed 50% liquid level (half-full) for holdup and horizontal vapor-area sizing
• Works in SI or US customary units
• Exports a PDF report with input/result tables and a vessel schematic

What This Tool Does Not Do

• Simulate the process or predict stream compositions
• Replace Aspen, HYSYS, or any other process simulator
• Model heat duty, feed conditions, or phase equilibrium
• Size nozzles, internals, or a complete mechanical design package

Typical workflow: simulate in Aspen (or similar) → copy outlet flows and densities → size the drum here → use the results for preliminary mechanical design.

Using the Desktop App

Getting data from Aspen Plus

After your simulation converges:

1. Open the FLASH2 (or equivalent flash/separator) block results.
2. Read the outlet vapor stream: mass flow rate and density.
3. Read the outlet liquid stream: mass flow rate and density.
4. Enter those values in Flash Drum Designer along with your target residence time and design parameters.

The built-in Load Example case uses representative propane/n-butane NGL outlet data so you can verify the tool — it is not a substitute for your simulation.

Main steps in the GUI

1. Choose unit system and orientation (horizontal or vertical).
2. Enter outlet stream data (vapor/liquid mass flow and density).
3. Set design parameters: residence time, K-factor source (GPSA table or manual), service type, demister option, L/D or H/D ratio, and vapor area margin.
4. For GPSA lookup, pick a table pressure (or enter a custom pressure) and specify whether the K-factor applies at, above, or below that pressure. The effective K-factor preview updates as you change settings.
5. Click Calculate to see sizing results in the results panel.

PDF reports

How you run the app	PDF behavior
Downloaded EXE	PDF is saved automatically next to the executable when you click Calculate. A dialog shows the full path. Use Save PDF Again to write another timestamped copy.
Run from source (py app.py)	Click Export PDF after calculating to choose where to save the report.

Design Basis (Summary)

Sizing applies published separator correlations to simulator outlet data. The tool does not recompute the flash.

Vapor disengagement — Souders-Brown:

$$V_{\max} = K \sqrt{\frac{\rho_l - \rho_v}{\rho_v}}$$

Required vapor flow area includes a configurable safety margin (default 20%). For horizontal drums, vapor area is based on roughly half the cross-section at 50% liquid level; for vertical drums, on the area above the liquid level.

Liquid holdup — drum volume sized for the requested residence time at 50% liquid level.

Final dimensions — diameter is the larger of vapor-side and liquid-side requirements; length (horizontal) or height (vertical) follows the selected L/D or H/D ratio, with vertical drums able to grow when inventory or disengagement needs require it.

Defaults: 5 min residence time, L/D or H/D = 4.0, K = 0.107 m/s when not using GPSA lookup.

GPSA K-factor table (gauge pressure)

Gauge pressure (bar)	K-factor (m/s)
0	0.107
7	0.107
21	0.101
42	0.092
63	0.083
105	0.065

The GUI applies GPSA service multipliers, demister/no-demister rules, and pressure-relation logic (at / below / above selected pressure). See the in-app K-factor preview for the value used in your case.

Assumptions and limitations

• Outlet properties are taken as given from your simulator
• Preliminary mechanical sizing only — confirm droplet settling, nozzles, mechanical design, and demister selection separately

For Developers

Requires Python 3.10+.

git clone https://github.com/f-ritz/flash-drum-designer.git
cd flash-drum-designer
py -m pip install -r requirements.txt
py app.py

Command-line interface

py flash_drum_sizing.py --vapor-mass 3.267 --liquid-mass 3.267 --vapor-density 79.42 --liquid-density 843.58

GPSA K-factor and PDF export:

py flash_drum_sizing.py --orientation vertical --use-gpsa-k --pressure 21 --vapor-mass 3.267 --liquid-mass 3.267 --vapor-density 79.42 --liquid-density 843.58 --pdf flash_drum_report.pdf

Imperial units:

py flash_drum_sizing.py --units imperial --vapor-mass 11760 --liquid-mass 11760 --vapor-density 4.96 --liquid-density 52.65

Run py flash_drum_sizing.py --help for all options.

Build the Windows EXE

.\build_exe.ps1

Output: dist\FlashDrumDesigner.exe. Optional icon: place assets/icon.ico before building.

Tests

py -m pytest

Project Structure

flash-drum-designer/
├── app.py                  # PySide6 desktop GUI
├── flash_drum_sizing.py    # CLI entry point
├── build_exe.ps1           # Windows EXE build script
├── FlashDrumDesigner.spec  # PyInstaller spec
├── assets/                 # App icon (icon.ico)
├── flash_drum_designer/
│   ├── sizing.py           # Souders-Brown and holdup sizing
│   ├── k_factor.py         # GPSA K-factor lookup
│   ├── examples.py         # Sample outlet-stream case
│   ├── units.py            # Unit conversions
│   ├── paths.py            # EXE and PDF path helpers
│   ├── pdf_export.py       # PDF report generation
│   └── theme.py            # Windows 10 GUI theme
└── tests/

License

Use and modify freely for engineering and academic work. Verify all results against applicable design standards before issuing for construction.