You Have Just Described the Average Concentrations in the Mixed Off-gas. But Won’t the first tank be a Worst Case, and Won’t the Off-gas from this Tank Pose an Explosion Risk?
No. (But don’t assume this will always be the the case for Methane Stripping Plants by different designers.) Two things can affect the above calculation. First, in the initial stripping reactor that receives incoming leachate directly, it is likely that between 60 and 70 percent of all methane will be removed, because of the “half-life” nature of the stripping process. Therefore, in off-gas from this tank, in the worst case calculation being carried out above, up to 15m3 of methane gas will be diluted into the flow of air from the air delivery system, each day. This generally represents a concentration of methane gas in air of about 5,000 ppm by volume, which is still a factor of ten below the LEL. A safety factor of ten times is widely used for gas safety in the mining industry, and indeed is exactly the reason that a discharge limit of 0.14 mg/l of dissolved methane in water is almost universally adopted for discharge of leachates and other liquids into the public sewer (since 1.4mg/
Related Questions
- You Have Just Described the Average Concentrations in the Mixed Off-gas. But Won’t the first tank be a Worst Case, and Won’t the Off-gas from this Tank Pose an Explosion Risk?
- Is it acceptable for the Feasibility Study to use the worst case scenario for key values and/or manufacturers?
- In either case, how would you suggest filtering this tank assuming a pretty small bioload?
