Mitigating buildup

In addition to reducing the probability of a dust explosion, it is possible to take steps to mitigate the consequences of a dust explosion, should one occur. Use of automatic vents to prevent the buildup of destructive overpressures and constructing areas with blowout partitions are examples of such steps. Also, spaces which may contain these high dust concentrations can be kept fairly open to minimize the development of turbulence in a flame front, should an explosion occur. 

Some waste feeds may contain a combination of abrasive particles and sticky salts. This can sometimes provide a benefit as tbe abrasive particles can scour the process surfaces and keep them sufficiently clear of solids buildup. U.S. Patent No. 5,620,606 teaches the addition of inert particles to SCWO feed to mitigate sohds build-up. 

Fouling (e.g., microbial adhesion, gel layer formation, and solute adhesion) at the membrane surface is a more complex phenomenon involving polarization, irreversible adsorption of macrosolutes or colloid particulates to, and/or gradual buildup of an adherent and coherent layer of solid material on, the membrane surface. It is amenable to mitigation by appropriate selection or surface treatment of the membrane surface (to minimize adsorption) by suitable fluid management or by employment of other forces to transport fouhng solutes. 

As alternative softening quaternaries, imidazolinium compounds have been introduced with a claim of superior rewet performance. This can be a useful performance feature because with continuing usage and buildup of cationics on the substrate, the water absorption of the substrate can be adversely affected. The use of anionic detergents in the main wash can mitigate this phenomenon because the anionic surfactant can combine with the cationic fabric softener to form a combination that is removed as part of the oil on the fabric. 

The use of biomass has been suggested as a way to mitigate the buildup of greenhouse CO2 in the atmosphere (6). Since biomass uses CO 2 for growth through photosynthesis, the use of biomass as a feedstock results in no net increase in atmospheric CO2 content when the products break down in the environment (7). 

When soap, which is sodium or potassium salt of various fatty acids, comes in contact with hard water, the fatty acids can be precipitated by the multivalent ions, which in high concentration forms soap scum. Of course, when soap was the only surfactant available, repeated heavy use of soap-only formulas without proper rinsing made soap scum buildup in hard water areas inevitable. The usual way to mitigate this effect is to formulate soap cleaners with chelants or builders to avoid the interaction with hardness ions. However, in practical use high amounts of builders can also leave mineral deposit on surfaces, visible as a dulling powdery residue if the cleaner is not thoroughly rinsed from the surface. 

Fig. 4. In situ mitigation of coke buildup with supercriticEil reaction media.

Another report of hydrogenation under SCF conditions from the patent literature includes claims for a continuous heterogeneously catalyzed hydrogenation reaction process by Subramaniam and Said (182,183). The primary focus of these patents is the in situ mitigation of coke buildup in porous catalysts, but an SCF-mediated hydrogenation process is a cited application (and claim). 

B Subramaniam, A Jooma. In situ mitigation of coke buildup in porous catalysts with supercritical reaction media effect of feed peroxides. In KW Hutchenson, NR Foster, eds. Innovations in Supercritical Fluids Science and Technology. ACS Symposium Series No. 608. Washington, D.C. American Chemical Society, 1995, pp 246-256. 

B Subramaniam, S Saim. In situ mitigation of coke buildup in porous catalysts with supercritical reaction media. PCT Patent No. WO 96/33148, 1996. 

In Situ Mitigation of Coke Buildiq) in Porous Catalysts by Prelreatment of Hydrocarbon Feed to Reduce PCTOxides and Oxygen Impurities In Situ Mitigation of Coke Buildup in Porous Catalysts with Supercritical Reaction Media... 

Containment hydrogen igniters are safety devices that mitigate the buildup of excess hydrogen in the reaetor building by slowly burning it off in the event of a nuclear ac-... 

A reactor operating in space may generate a significant electrical charge buildup on the spaceship. Actions will need to be taken to characterize, test and mitigate this effect to ensure spaceship operations are not affected. 

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