Test Method for Total Chlorine in New and Used Petroleum Products by Oxidative Combustion and Microcoulometry according to IP 9076 resp. UOP 9076 Application Note · multi EA 5100

Introduction

New petroleum products have to be tested for their chlorine content to ensure a sufficient product quality. Only this way undesired effects like corrosion and wearing of system components like engines, combustion and exhaust systems, tanks and nozzles, can be avoided when they are used as fuels (e.g., kerosene), combustibles for heating and power generation (e.g., diesel oil), or engine, lubricating or crankcase oil. That’s why the chlorine contents generally are very low for new products. In contrast, used oils (e.g., transformer oil, vegetable oil) can be heavily contaminated with chlorine compounds due to their use. The chlorine content can vary from few ppm up to the wt% range. As a precondition for disposal and recycling of organic waste oils and related matrices the chlorine content has to be determined. Especially when being utilized as refused derived fuels (power generation, etc.), these matrices have to be strictly controlled to avoid not only exceedance of permissible emission limits (HCl), but also damages of the combustion system. Chlorine contents higher than 1 wt% significantly contribute to the formation and precipitation of alkaline and other metal chlorides at the colder installation parts like heat exchangers. This negatively affects performance, maintenance cycles, and finally, the economic life of these components.

In contrast to the classic methods – bomb digestion, Schöninger or Wickbold combustion – the combination of oxidative combustion with microcoulometric detection allows more flexibility, faster sample processing, as well as matrix- and content-independent quality of chlorine results.

The precondition for this method is the complete separation of the chlorine from the original sample matrix. This is more or less difficult, depending on the complexity of the sample composition. Especially long-chained, unsaturated, branched and cyclic compounds tend to vigorous digestion (spilling, smoldering, pyrolysis) when being heated up. In case of such an incomplete combustion, the chlorine recovery also is affected. This is due to the fact that the formed soot (mainly elemental carbon and other highly condensed carbon compounds) tend to adsorb the generated hydrochloric acid. This is comparable to the adsorption on charcoals for AOX sample preparation and is even worse in case the contamination and residues are located at cold parts of the analysis system.

The multi EA 5100 offers a quick and reliable analytical solution. Its flame sensor technology effectively prevents incomplete combustion. This and intelligent performance-enhancing features, such as the auto-zero and the automatic drift control, ensure a stable system performance, independent of the chlorine content of the analyzed matrices. The used microcoulometric “sensitive“ cell option is able to determine chlorine quantities as low as 100 ng up to 100 µg. This way a unique wide concentration range can be covered with one and the same analysis method. A sample dilution is not necessary thanks to the unique wide operation range of the sensitive cell option.