ABB’s new Navigator 500 analyser family brings a compact, reliable and accurate range of instruments for high purity water treatment and boiler chemistry monitoring applications. Providing continuous online monitoring of boiler feed water quality, the Navigator 500 Hydrazine, Dissolved oxygen and sodium analysers help ensure optimum efficiency of both boiler plant and ancillary equipment throughout the steam distribution loop. The second in the Navigator analyser series, the Navigator 500 joins ABB’s Navigator 600 Silica and Phosphate devices for power generation applications.
A key feature across the Navigator 500 series is its separate sensor and transmitter section design. All analysis and signal conditioning is conducted within the sensor section and transmitted digitally to the transmitter. Each transmitter can collect data from up to four sensors. This enables monitoring at multiple points without the cost associated with purchasing and installing separate transmitters. The four transmitter inputs can be used to collect signals on one parameter or can be mixed and matched, with multiple parameters being fed to one unit. In contrast to traditional single-stream devices, the Navigator 500 Sodium sensor can also be configured for multi-stream analysis, with up to three sample streams able to be handled by a single sensor unit. Each analyser within the series is based on ABB’s proven chemical analysis technology.
The Navigator 500 Hydrazine is used for applications where hydrazine is used to dose boiler feed water to reduce dissolved oxygen levels. The sensor uses an electro-chemical cell to accurately measure the amount of hydrazine in boiler feed water. This accuracy is reinforced by temperature compensation, which, coupled with a fast response time, helps ensure that readings reflect the actual feed water conditions. The information provided by the analyser makes it possible to avoid expensive overdosing of hydrazine or the avoidance of more costly corrosion damage to the boiler plant due to the under-dosing of hydrazine. The Navigator 500 Dissolved Oxygen uses a galvanic-type sensor to accurately measure dissolved oxygen levels in process feed water. It can be used to measure dissolved oxygen throughout the feed water system as well as an indicator of hydrazine dosing efficiency. Accurate and reliable, it requires no maintenance and monitors dissolved oxygen levels across a wide concentration spectrum up to 20 parts per million.
The Navigator 500 Sodium provides a continuous measurement of sodium concentrations. It uses ABB’s sodium ion-selective electrode and reference electrode to measure the sodium ion concentration in demineralisation plants and in the steam/water cycle of steam-raising plants. The Navigator 500 Sodium requires very little maintenance and measures sodium ion concentrations within the range 0.10 ppb to 10 ppm. This accuracy is reinforced by automatic temperature compensation, ensuring that readings reflect the actual process conditions. Other key features of the Navigator 500 Sodium include a grab sample mode and automatic electrode regeneration. The grab sample mode enables the device to be used to test a sample from elsewhere in the plant. Unlike conventional devices where the operator needs to switch to analysis mode, wait for a reading and switch back to measurement mode, the Navigator 500 Sodium stores a reading in its audit log and automatically switches back to measurement mode as soon as the analysis is done. This eliminates the need for the operator to wait for a reading, which can take several minutes.
The automatic electrode regeneration helps to prolong the life of the sensor electrode, particularly useful in applications where sodium needs to be measured at very low levels for long periods. To prevent diminishing sensor performance, the Navigator 500 Sodium can be preset to automatically regenerate the electrode by adding a regeneration reagent at set periods. Other features across the series include automatic calibration and optional manual flow control, enabling operators to manually set the stream flow rate into the wet-section. All versions also incorporate an easy to read sensor efficiency indicator, enabling operators to quickly check sensor efficiency and expected sensor lifetime.
The inherent product design, low reagent requirements and auto-calibration features of the analysers, coupled with the elimination of any moving parts, makes them simple to maintain.
The Navigator 500 Dissolved Oxygen analyser uses ABB’s maintenance-free dissolved oxygen sensor. Featuring an encapsulated design, the sensor removes the need for time consuming maintenance such as membrane changes or electrolyte replenishment. The ‘pump less’ design of the Navigator 500 Sodium reduces maintenance requirements compared to alternative products. The automatic electrode regeneration feature also further reduces routine maintenance when measuring low sodium levels.
The Navigator 500 Hydrazine uses a micro-porous disc to deliver reagent to the sample. This eliminates the need for reagent pumps or diffusion tubing. The robust hydrazine measurement cell can also be refurbished by the user to maximise sensor life. The transmitter is also available with the option of digital communications, including Ethernet capability, enabling data to be relayed to a central control room.
The release of the Navigator 500 series further strengthens ABB’s continuous water analysis portfolio for high purity water treatment applications and power cycle chemistry monitoring, augmenting its existing strengths in other parameters such as silica, phosphate, pH and conductivity.
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