TOC Analyser for pure water: online measurement of organic carbon in low ranges

The analysers process control is specially designed for the determination of TOC (total organic carbon) in boiler feed water, condensate return, cooling water and process water. Thus, support and maintenance efforts are significantly reduced. The application-specific, custom-made measuring system provides benefits in pure water analysis.

A TOC Analyser for pure water: QuickTOC_purity.
The QuickTOCpurity is equipped with a closed injection loop where a subset of a water sample is injected into the furnace. Thus, contamination of the sample by substances in the ambient air is avoided. In addition, VOC and POC (volatile/purgeable organic carbon) are not released and hence, are included in the measurement. The process control of the TOC system is an advantage, especially in chemical and petrochemical plants, in which various substances can be present in the air.

The furnace is the centerpiece of the QuickTOC_purity. It uses the patented high-temperature combustion method at 1200°C. The high temperature ensures the complete digestion of all carbon compounds in the sample. Oxidation promoting catalysts, such as those used in other measuring methods, are unnecessary. As a consequence, the operating costs of the measurement system are minimised.

Due to the thermal combustion carbon dioxide is produced, which is measured with a NDIR detector and then, the TOC value is quantitatively determined. The total measurement is done in less than 3 minutes. In pure water analysis it is common practice to verify the correctness of the measurement result in the case of exceeding the threshold. In order to verify the accuracy of the measurements, the QuickTOC_purity is equipped with the patented calibration feature QuickCalibration. The calibration and validation of the TOC analyser is performed by means of a test gas. Such a gas is long-term stable, low in purchasing and can be positioned permanently near the device. Thus, the QuickTOC_purity can be calibrated and validated with a touch of a button, and even via remote control form a control room. Consequently, the purchase or production of high-purity aqueous standards, which customarily are used for calibration/validation, is not required.

The QuickTOC_purity is designed for the measurement of up to six sample streams in one device. Each sample stream can have different combinations of parameter such as TOC, TC, TIC, COD and/or TN_b. Various process streams can so easily be monitored in a single analyser. The QuickTOC_purity is controlled via a 10.4“ touchscreen display. Access to the measuring system can even be done via internet protocol for example from a control room.

The process control of the TOC analyser QuickTOCpurity is aligned to measure low particulate samples and even hot samples of up to 95°C. Especially in water-steam cycles, the samples cooling can be avoided. The custom-made analyser takes care of the concrete challenges of pure water applications such as boiler feed water, cooling water and condensate return, minimising maintenance efforts and making the optimisation and control of complex processes possible.