EcoWater CHC Series, Service And Troubleshooting Manual, Page: 22 / 130

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3.3 HOW CHC WORKS
CHC chemical-free cooling water treatment has been in service over 15 years and is unlike all other
non-chemical technologies currently available. The technology essentially consists of two side-stream
water loops typically connected into the sump or basin of the cooling tower/evaporative condenser. One
loop acts as a side stream filter. The second side stream loop is where cooling water passes through a
pair of horizontally opposed vortices and is accelerated to a very high velocity at the discharge. At the
point of discharge, the two opposing water streams (whose internal rotation is opposite from one another)
collide, creating hydrodynamic cavitation, shear force, and vacuum.
This sudden lowering of pressure into a vacuum state forces the release of dissolved carbon dioxide
(CO
2
) from the water. This release of CO
2
in turn, causes calcium carbonate to immediately drop out of
solution into suspension where it is removed by filtration. Unlike other non-chemical technologies, CHC
is relatively impervious to alkaline or acidic source water, high or low pH, hardness, TSS or TDS, all of
which are parameters that may render other forms of cooling water treatment less desirable. Additionally,
it is relatively easy for operational personnel to see if this system is working, because it can be either
remotely monitored or monitored on-site by physical observation of the pump status and a vacuum gauge
which measures vacuum being created inside the CHC chamber.
System Operation: Water is pumped from the sump/basin of the cooling tower/condenser and into the
pressure-equalizing chamber. It is then channeled into precision-manufactured nozzles (vortices) that are
configured to impart a specific rotation and velocity to the water streams. The circular motion of the water
is accelerated as the stream flows through the nozzles and the resultant discharge is a conical stream.
The opposing cones collide in the low-pressure stage (stabilizing chamber) to form a circular zone of very
high shear force and high vacuum caused by the collapse of micrometer-sized bubbles and cavities.
Essentially, the pressure change causes hydrodynamic cavitation with locally high temperature at the
point of collision. This cavitation creates solid particles, and the rapid change in pressure to a vacuum
causes the cell walls of microorganisms to burst, thus killing the cell. Finally, the hydrogen-bonding
molecular arrays of water are broken down, thereby allowing entrapped gasses (such as CO
2
) to be
released and off-gassed to atmosphere. The remaining energy dissipates as turbulent flow, and the
treated water exits the unit at ambient pressure. Suspended matter is removed from the sump/basin via a
second side stream loop designed to sweep the debris from the floor of the sump into the automatic filter
or centrifugal separator. The filter is automatically backwashed to remove solid matter on a timed basis
and is then sent to waste.
Biological Control : CHC technology is in sharp contrast to chlorine or bromine treatments that degrade
over time and require constant additions. During biocide dosage the bacteria cell must ingest chlorine or
bromine. This often takes up to 30 minutes if and when the cell comes in contact with a chlorine molecule,
and is therefore not always 100 percent effective. CHC technology causes a combination of physical
changes to take place in the water that disrupt the cell membranes of biological matter, ultimately
destroying the cell. Every cell pumped through the system is subjected to vacuum, high pressure, kinetic
energy, high velocity collision, shear energy, and localized high temperatures. The pressure of the fluid
inside the cell wall is in balance with ambient water pressure prior to its entrance into the CHC chamber.
However, the pressure differential becomes relatively high once the cell enters the low-pressure stage that is in
vacuum, resulting in a pressure imbalance between the inside and outside of the cell. The cell wall cannot
withstand the pressure differential and the cell wall ruptures, dispersing the cell cytoplasm. After the lowpressure
stage, localized high temperature and high pressure at the intersection point of the vortices also
kills additional bacteria and cell life.
Scale and Hardness Control: Cooling systems build up scale over time due to the addition and
concentration of soluble calcium often in the form of calcium bicarbonate. Calcium bicarbonate can
decompose to yield insoluble calcium carbonate and carbonic acid with any changes in temperature and
pressure. Carbonic acid can further decompose to carbon dioxide and water. (Ca(HCO
3
)
2
)↔
CaCO
3
+CO
2
+H
2
O, or (Calcium bicarbonate) ↔ (Calcium carbonate) + (carbon dioxide) + (water). At a
given temperature and pressure, this equation is in equilibrium with no chemical reaction taking place.
Once the pressure is lowered to a vacuum in the low pressure stage, the CO
2
equilibrium is shifted
between aqueous and gas phase, causing dissolved CO
2
to release to the gas phase. This phenomenon,
together with the high localized temperature created by the collision of the conical water streams,
decreases the solubility of calcium in water and a simultaneous elevation of water pH, which, in turn,
causes a massive formation of calcium carbonate precipitate. Soluble calcium carbonate species
concentrations are thus depleted (by design) both via de-adsorption of CO
2
and the precipitation of
CaCO
3
. As the water stream leaves the CHC unit it enters the sump/basin where the water pressure is