Stack Height

by Constantin
(Romania)

I need to size the height of a dispersion stack for the hydrogen sulphide.

Barry's Response - Hi Constantin:

Determining the optimal height for these stacks is what I do mostly. What I use for inputs in this type of assessment is:

If the stack is to be used as a gas flare:
1 - Flow rate (cubic metres per day for example) at standard temperature and pressure
2 - Gas composition with mole fraction (or percent) for each component, or at least gas heating value and H2S content
3 - The stack exit diameter, at the tip
4 - Location of stack (longitude and latitude)
5 - The applicable air quality standards in your country for one-hour, 24-hour and/or annual H2S and SO2 concentrations (in ppm or µg/m3).

If the stack has no flame coming from the tip:
1 - The stack diameter
2 - The exit temperature
3 - The exit velocity
4 - The H2S and/or SO2 emission rate (in grams per second for example)
5 - Location of stack (longitude and latitude) and position relative to nearest buildings, along with building dimensions.
6 - The applicable air quality standards in your country for one-hour H2S and SO2 concentrations (in ppm or µg/m3).
7 - These same parameters will also work for sources of NOx particulate and various other species.

This information will allow a simple screening assessment. To make for a more refined study I would need:

1 - Stack base elevation and terrain maps with elevations in the general region of the flare site, usually within 10 kilometres.
2 - At least one year (preferably five) of hourly observed meteorological data. Temperature, wind direction, wind speed, sunshine intensity are useful input parameters for the ISC-PRIME model (for instance).

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