Why Superheated Steam?
Using the superheated-steam process is the safest, most cost-effective and thorough method to clean up both bulk and residual quantities of alkali metals. The advantages:
- The reaction is extremely controllable and easily stopped in an emergency.
- When the steam is shut off, the minimal amount of moisture in the gas space is consumed or vented.
- Response time is typically less than one minute.
- The vessel containing the alkali metal is kept at atmospheric pressure.
- Actually the vessel is kept slightly positive (~5"w.c.).
- There are no pressure “excursions.”
- Reaction end points are very distinct and readily discernable with a high degree of certainty.
- When the upper surface of the alkali metal is fully reacted, there is no more live metal.
- There are no pockets of metal shielded by hydroxides or their hydrates.
- The high temperatures mean that the caustic formed is anhydrous, which provides the following advantages:
- The anhydrous caustic stays molten (above 605°F), so there are no inclusions.
- The density of the molten caustic is significantly higher than the alkali metal, so the caustic settles at the bottom of the vessel and the metal stays at the top, continuously exposing fresh surfaces for reaction.
- Alkali metals are typically not miscible with their caustic reaction products, so there is a distinct interface with the metal on top, making the end point of the reaction easier to detect.
- High moisture-injection rates means the alkali metal gets very hot (> 800°F).
- This assures there is no moisture accumulation either from the steam or hydrate formation.
- No “rollover” reactions occur because of a spill of hydrated caustic into live metal.
- The reaction zone is simply too hot for moisture to exist as a liquid.
- Moisture is introduced into the gas space of the vessel; the upper portions and sidewalls of the vessel are exposed to the moisture and cleaned very thoroughly.
- Metal-free caustic is produced, which can be used as a substitute for commercially purchased caustic.
Easily cleans piping systems in-situ, although careful study and preparation may be required. - There are NO POPS, BANGS OR SUDDEN PRESSURE SURGES.
- Carbon and stainless steel can be used. Tanks are typically suitable for re-use.
- Does not add organics, which might have regulatory impacts or introduce additional fire hazards.
- Does not add any potentially toxic materials to the processing area.
- Capable of cleaning the following:
- Reactors and tanks of any configuration
- Tanks and equipment of extremely complex geometry
- Cold Traps
- Valves
- Heat Exchangers
- Piping
- Pumps
- Finally, metal can be reacted at rates of several hundred pounds PER HOUR, meaning the project will be completed quickly.
- CEI’s processing equipment is fully skid-mounted and takes only about one week to set up.
If you wish to learn more about the superheated-steam process or the advantages and disadvantages of the other processes, call Creative Engineers at 443-807-1202.