电厂水中TOC分析

analytikjena Field of Application/Industrialsector： Chemistry/Polymer Industry Electronics Energy Nutrition/Agriculture Geology/Mining Semiconductor Technology Clinical Chemistry/Medicine/Hygiene/Health Care Cosmetics Material Analysis Metallurgy/Electroplating Pharmacy Refineries/Petrochemistrv Environment/Water/Waste Other Short Application of the Sum Parameter Analysis - TOCDetermining TOC in Power Plant Waters Introduction Waters within power plants， and particularly boiler feed waters are subject to strict analyticalcontrol. Organic impurities in the boiler feed water can easily be oxidized under high pressure andhigh temperatures， and may lead to the formation of corrosive organic acids and carbonic acid.Salts are often added as oxygen scavengers. TOC monitoring in the boiler feed water is crucial for controlling this process. This is a matter oftrace contamination in the range below 1 ppm TOC. Wet chemical UV digestion is particularly suited for the TOC determination within this concentrationrange and this matrix， not least due to its large volume of sample injection (up to 20 ml) and itshigh measurement sensitivity. Experimental A similar matrix as generally found in power plant waters was synthesized and defined TOCcontents wereadded. The following concentrations and substances were used for the synthetic matrix： 7 g/l boric acid 1 mg/l sodium 7 mg/l potassium ●22 mg/I lithium 7 mg/l ammonium A 300 pg/l and a 1000 pg/I TOC-standard (potassium hydrogen phthalate) were then added to thissynthetic solution. The synthetic samples were adjusted to pH 2 with 2N sulfuric acid. The following method parameters were set at the instrument system. Measurementparameters NPOC Digestion technology Wet chemicalUV digestion (185nm and 254 nm) Number of repeated measurements 3 of4 Purging time 300 seconds Injection volume 5000 ul Additional reagents(oxidizing agent) No A TIC control measurement ensured that the inorganic carbon and dissolved carbon dioxide hadbeen eliminated. An autosampler with parallel purging and analysis function was used for feeding the sample. Thisreduces analysis times and allows a high sample throughput. The non-purgeable organic carbon (NPOC) proportion was oxidized to CO2 in the UV reactorwithout additional use of an oxidizing agent and determined by means of an NDIR detector. Calibration The software of the analyzer allows the combination of one measuring method with severalcalibration ranges. The most suitable calibration curve for calculating the results is automaticallyselected by the analyzer based on the surface integrals. This ensures that the optimal calibrationrange is always selected. This is particularly user-friendly and guarantees highest accuracy andprecision of the measured values. A single-point calibration with 1000 ppb TOC was prepared frompotassium hydrogen phthalate for the synthetic samples for the field of power plants. Results The following table shows the mean values of the NPOC measurements as well as the relativestandard deviation. Summary The results show that there is no need to add an oxidizing agent charged with a TOC blank valuesuch as sodium peroxodisulfate for the complete oxidation of waters in the field of power plants.The UV radiation and the dissolved oxygen in the sample are sufficient to convert all organiccompounds into CO2. The results are extremely reliable TOC measurements in the boiler feedwater， other ultrapure waters and even in drinking water analyzes. Printout and further use permitted with a reference to the source. C 2013 Analytik Jena AG Analytik Jena AG Konrad-Zuse-StraBe 1 07745 Jena Determining TOC in Power Plant Waters/Reference number： SP TOC d||SF