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Effectiveness of Threshold Inhibitors
When properly fed, a threshold Inhibitor is 100%
protective within the limits of its application. Outside these limits,
performance is noticeable.
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If the T.I. is underfeed,
there is not any protection at all,
and the system ignoring the small amount of antiscalent present,
precipitates exactly the same deposits volume, at the same time, at the same
positions, like in the untreated system.
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If the T.I. is overfeeding, then it
looses its Threshold Inhibition properties.
It looses the 100% protection, and according to the specific substance can
act either as sequestrant (ATMP) or be completely inactive (HEDP).
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If a T.I. based treatment is applied to a
non-clean system, means where deposits and crystallization nuclei are
already present, then:
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Under normal feeding rate achieves
partial protection, which can be 40-60% of the expected. Means that
system is not scale protected, but scaling development is lowered.
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Under overfeeding conditions, establish
100% protection, while existing scales are slowly re-dissolved.
So the use of T.I. being cost effective is
mostly a matter of art, and special care has to be taken to the design of the
treatment, to the system characteristics and to the T.I. mixture compositions.
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