“…The transmittance response of the sensor showed slightly better sensitivity in the near-infrared region than in the visible region. This tendency is similar to the results of our previous measurement for CaCO 3 scale, which has a higher refractive index than the quartz fiber core 41 . The result indicates that the sensor is able to detect not only CaCO 3 but also silica scale formed in geothermal water.Figure 1( A ) Transmittance response monitored by the fiber sensor with 8 cm exposed core length at 600 nm (blue line) and 1300 nm (red line) as a function of time after immersion in a solution containing 1000 mg/L silicate (as SiO 2 ).…”
Section: Resultssupporting
confidence: 91%
“…Several groups have reported the fiber optic method for monitoring CaCO 3 precipitation by using an exposed core fiber and monochromatic laser light 37–40 . In our previous work, we proposed an optical fiber sensor that uses an exposed core fiber, white light, and a spectroscopy detector for monitoring CaCO 3 scale formation in geothermal water 41 . The detection principle of this sensor was based on the percentage of total internal reflection within the fiber optic core, which is affected by the high refractive index of CaCO 3 scale formed on the surface of an exposed core.…”
We present a novel fiber optic sensor for real-time sensing of silica scale formation in geothermal water. The sensor is fabricated by removing the cladding of a multimode fiber to expose the core to detect the scale-formation-induced refractive index change. A simple experimental setup was constructed to measure the transmittance response using white light as a source and a spectroscopy detector. A field test was performed on geothermal water containing 980 mg/L dissolved silica at 93 °C in Sumikawa Geothermal Power Plant, Japan. The transmittance response of the fiber sensor decreased due to the formation of silica scale on the fiber core from geothermal water. An application of this sensor in the evaluation of scale inhibitors was demonstrated. In geothermal water containing a pH modifier, the change of transmittance response decreased with pH decrease. The effectiveness of a polyelectrolyte inhibitor in prevention of silica scale formation was easily detectable using the fiber sensor in geothermal water.
“…The transmittance response of the sensor showed slightly better sensitivity in the near-infrared region than in the visible region. This tendency is similar to the results of our previous measurement for CaCO 3 scale, which has a higher refractive index than the quartz fiber core 41 . The result indicates that the sensor is able to detect not only CaCO 3 but also silica scale formed in geothermal water.Figure 1( A ) Transmittance response monitored by the fiber sensor with 8 cm exposed core length at 600 nm (blue line) and 1300 nm (red line) as a function of time after immersion in a solution containing 1000 mg/L silicate (as SiO 2 ).…”
Section: Resultssupporting
confidence: 91%
“…Several groups have reported the fiber optic method for monitoring CaCO 3 precipitation by using an exposed core fiber and monochromatic laser light 37–40 . In our previous work, we proposed an optical fiber sensor that uses an exposed core fiber, white light, and a spectroscopy detector for monitoring CaCO 3 scale formation in geothermal water 41 . The detection principle of this sensor was based on the percentage of total internal reflection within the fiber optic core, which is affected by the high refractive index of CaCO 3 scale formed on the surface of an exposed core.…”
We present a novel fiber optic sensor for real-time sensing of silica scale formation in geothermal water. The sensor is fabricated by removing the cladding of a multimode fiber to expose the core to detect the scale-formation-induced refractive index change. A simple experimental setup was constructed to measure the transmittance response using white light as a source and a spectroscopy detector. A field test was performed on geothermal water containing 980 mg/L dissolved silica at 93 °C in Sumikawa Geothermal Power Plant, Japan. The transmittance response of the fiber sensor decreased due to the formation of silica scale on the fiber core from geothermal water. An application of this sensor in the evaluation of scale inhibitors was demonstrated. In geothermal water containing a pH modifier, the change of transmittance response decreased with pH decrease. The effectiveness of a polyelectrolyte inhibitor in prevention of silica scale formation was easily detectable using the fiber sensor in geothermal water.
“…The transmittance change was recorded in the 400–1600 nm range using a spectroscopic detector. Previously, we reported that the sensitivity of the fibre optic sensor for scale formation depended on the detection wavelength 19 . However, the relationship between these transmittance changes was the same at any detection wavelength employed in the field tests.…”
Section: Resultsmentioning
confidence: 99%
“…However, these methods to detect changes in the amount of deposited scale are time-consuming, taking a few days to months to be performed. Previously, we proposed the use of a fibre optic sensor that relies on an exposed fibre core, halogen light and a spectrometer to monitor scale formation in geothermal brines 19–22 . The ability of the fibre optic sensor to detect the presence of scale was based on the percentage of total internal reflection within the fibre optic core, which is influenced by the high refractive index of the scale formed on the surface of an exposed fibre core.…”
Treatment with an electromagnetic field, one of the potential techniques to inhibit scale deposition from water, has the advantage of not requiring the addition of any chemicals. Field tests using a fibre optic sensor were conducted to evaluate the effect that the treatment of hot spring water in Matsushiro, Japan with an electromagnetic field had on calcium carbonate scale formation. The optical response to scale deposition recorded by the fibre optic sensor decreased as a consequence of the application of an electromagnetic field, and the effectiveness of scale formation inhibition depended on the frequency of the electromagnetic field. This evidence was compared with results from changes in scale mass measured using the quartz crystal microbalance (QCM) method. Mass increases of the scale formed on the quartz crystal surface in hot spring water were inhibited by electromagnetic field treatment. These results were verified performing a column flow test, whereby the flow rate of hot spring water through a column was measured.
“…31,32 The sensor detection principle is based on the optical transmittance over a wide wavelength range, which is affected by the high refractive index of CaCO3 or silica scale formed on the exposed core. In addition, we proposed a spectroelectrochemical fiber-optic sensor, whose sensitivity for model analytes can be controlled by electrostatic modification using self-assembled monolayer (SAM) formation on the surface of the fiber-optic core.…”
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