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Fundamental Principles
Silica refers to the reactive silica in pure water, such as
boiler feedwater, deionized water, steam condensate, and
RO permeate used in power plants, boiler or ultrapure
water applications. It is a very important indicator for
detecting and controlling the corrosion or scaling on
turbines, heat exchangers, and boilers. Online real-time
measurement of silica enables safe, efficient operation,
reduces maintenance, and replacement costs due to
scaling. The online silica analyzer allows instantaneous or
automated decision making, enabling removal or recycling
of water with out-of-range silica concentration. Continuous
silica monitoring provides rapid notification of RO
breakdown or saturation of ion exchange resins, thus,
ensuring maximizing system efficiency and minimizing
downtime for repairs. Orion 8030cX Silica Analyzer can
send alerts/alarms or data to warn the users at the onset
of silica spikes, triggering corrective actions and reducing
failure and issues downstream.
Orion 8030cX Silica Analyzer is based on the detection
principle of the Heteropoly-molybdenum blue colorimetric
method. In this process, silica reacts with molybdate in
acidified condition to form siliconmolybdate yellow. This
is an intermediate then reacts with reductant to generate
siliconmolybdate blue. The absorbance of this blue
complex at a specific wavelength is proportional to the
silica content. After calibration, the silica concentration
(unit: µg/L or ppb) in the water sample can be reported.
Interferents such as phosphate (PO
can cause significant false-positive errors. Therefore, the
masking reagent R2 is added to prevent formation of
intermediate reaction products which interfere with the
molybdate method, thereby enabling more accurate
results.
8030cX Silica Analyzer
3-
) and arsenic (As)
4
Below 30 mg/L, the phosphate (PO
3-
(AsO
) ions will not interfere with silica test results. In
4
standard boiler water, ultrapure water, Ion exchange resin
effluent, mixed-bed demineralizer effluent and RO
permeate applications, the phosphate (PO
3-
arsenate (AsO
) ions will not exceed the 30mg/L
4
threshold, so the results of 8030cX Silica Analyzer will be
accurate without interference.
Orion 8030cX Silica Analyzer includes the following parts:
the electronic control system and water sample analysis
system.
The electronic control system includes the power supply
module, circuit control system and user interface panel,
and it has the functions of instrument power-on, self-test
and fault alarm. Historical analysis data, alarm data,
calibration and event log are stored in the instrument for
one year or even more, which users can download via USB
drive. The real-time data can also be transmitted to
external equipment (PLC or DCS) through 0/4-20 mA
output signals or RS485. The user can set the
measurement time, measurement frequency, calibration,
cleaning and validation frequency according to the site-
specific requirements.
The water sample analysis system includes the water
sampling flow cell, reagents delivery sub-system, reaction
cell, and measurement and analysis module. The water
sample and reagents are delivered by a newly designed
fluidic sampling system to ensure a higher measurement
accuracy. The instrument has implemented an accurate
temperature control on the color reaction process to
ensure the colorimetric reaction proceeds to completion.
Optical background correction was implemented
reduce background interference. Pre-analysis and post-
analysis rinses and cleaning procedure are built in each
measurement to ensure accurate result without carry over
effect or contamination.
Product Overview
3-
) and arsenate
4
3-
) and
4
to
Chapter 2 | 7
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