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Heat
exchange of water undergoes a complex chain of reactions resulting
in both alkaline and acid scaling. Flow dynamics, quality of
water, pressure variations and complexity of chemical reactions
make predictions difficult. This scaling phenomenon is directly
related to alkalinity and hardness in which heat exchange provides
the trigger point for this chain to begin. Alkaline scale
formation begets from the decomposition hydrolysis of bicarbonate
ion as process temperature is increased. Starting with Reaction
A (3 HCO3
- + 3 H2O ↔ 3 CO3² - + 3 H2OH+). Once the solution is heated,
alkalinity in form of bi carbonates combines with water to form
CO3² and hydronium ions. This results in immediate variations in
pH values and resultant inability to accurately predict scale and
sludge formation. In Reaction B (CO3 2- + Ca2+ →CaCO3 ↓)
Carbonate ions then combine with Calcium ions to form a compound
that forms hard scale on the contact surfaces. At Reaction C
(2 CO3²- + 2 H2O ↔2 HCO3 - + 2 OH-), carbonate ions combine
with water to produce bi carbonates and hydroxyl ions. At
Reaction D (2 OH- + Mg2+ →Mg (OH) 2 ↓), the short lived
hydroxyl ion cycle quickly combines with magnesium ions to form a
precipitate of magnesium hydroxide. It is assumed that steps A to
D support deposition of calcium carbonates ahead of magnesium. At
Reaction E (3 HCO3 - + 3 H2OH+ →6 H2O + 3 CO2 ↑), hydronium
ions react with bicarbonates to form water and carbon dioxide
lowering the localized pH conducive to acid scaling of silicates
and sulphates, a much harder form of scale. This step is probably
related to the pressure fluctuations inside the heat exchange
tubes. At Reaction F( 4HCO3 - + Ca2+ +Mg2+ →CaCO3↓+ Mg
(OH)2 ↓+ 3CO2 ↑+ H2O) a double reaction of calcium and magnesium
precipitate in the given order forming carbon dioxide and water
again leading to acid scaling of silicates and sulphates. This is
one explanation why scaling occurs as honeycombs.
Some of
the most glaring effects of EcoBeam XL are: -
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Changes in pH.
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There are rapid changes in pH of water due to formation of
negative ions, bicarbonates and carbon dioxide. However, the
common practice is that pH values of solutions are measured from
samples drawn out of heat exchanger tubes of recovery section
and not conclusive. EcoBeam XL will stabilize the pH through
creation of additional hydrogen and hydroxyl ions and obviate
the use of complicated and impractical pH monitoring. These
ions, combined with flow dynamics will remove all existing scale
in the system accessible to this energized water and inhibit
future scaling and corrosion. The sludge formed thereof will be
carried away by the flow of the water.
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Scaling and Hydro Dynamics.
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Though the explanation above caters for the likely chemical
reactions, it ignores the aspects of hydro dynamics created due
to heat, flow of water and additions of chemicals in water to
control scaling and corrosion. Molecular clusters of water
carrying their own electrical charge as well as that of the
dissolved solids within them intersect each other’s electrical
fields while passing through valves, housings and surfaces
creating turbulence. The rapid rise and fall in temperatures act
as initiators of another chain of chemical reactions that would
constantly be different at different nano seconds. Scale
precipitation inside tubes is not only from initial scale
formation under pressure but also due to nucleate recirculation
due to recycling. EcoBeam XL will stabilize all chemical
reactions, separate all peripheral dissolved solids that form
scale and enhance the performance of the plant under varying
flows and temperatures. The electrical energy (zeta potential)
of the scale forming compounds will be used to stabilize pH and
form soft slimy sludge instead of hard alkaline and acid scale.
At the same time it will be the silicates that shall initiate
the process of acid sludge while the other sludge will collect
around it.
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Reduction in Pressures and
Role of Carbon Dioxide.
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Formation of carbon dioxide raises the pressure inside the
vessels, affecting formation of steam. Some combines with it to
make the water acidic. In case of EcoBeam XL, Hydrogen Ions
being positive will form a pattern along the surfaces of pipes
and chambers. Carbon dioxide formed will convert to carbonic
acid which in turn will deplete the hard scale. Because most of
the CO2 will be utilized to deplete scales as a result,
pressures in the vessels will reduce.
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Corrosion.
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The formation of
hydrogen ions and them being attracted to the sidewalls of the
pipes that are ground negative besides removing existing hard
scales also forms a thin film by reacting with existing
corrosion to reverse the damage and inhibit further corrosion
not only in the tubes but also throughout the system.
Before and After
Conditions of Heat Exchanger and Pipes with EcoBeam XL on
installations in Japan
Read More Related Topics:
Cooling Towers I
Heat Exchangers
Evaporators & Distillers I
Blow Down
I
Scale Preventions
I
Corrosion Control I
Control of Biological Growth
I
Fuel I
Water Treatment |
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