AAI Tackles EDC

The production of the PVC that carries our water, insulates our power cables, lines our kitchen floors, and entertains our children is a process which has much to gain from the utilization of AAI analyzers. Ethylene dichloride (EDC) is the first
intermediate in the manufacturing of the versatile plastic from the raw materials of chlorine and ethylene. In combining Cl2 and C2H4, EDC is created; while this compound is useful on its own as a strong solvent, over 90% of the EDC produced is dedicated to vinyl chloride monomer (VCM), the chemical precursor to PVC. 1,2- Dichloroethane, as EDC is also known, is heated to around 500°C in a cracking furnace, eventually splitting into the desired VCM and recyclable dry HCl. The products are quickly cooled to avoid recombination, after which unreacted EDC is returned to the furnace and the HCl byproduct is reserved for oxychlorination, a second method for creating EDC.

Applied Analytics provides three applications which prioritize efficiency, product quality, and safety within this specific chemical process.



Component: Water
Range: 0-20 ppm

Those overseeing chemical systems must always consider the threat of corrosion, and monitoring the water level to a specificity of 0-20 parts per million is the first line of defense. AAI's Microspec is designed to monitor low and high water contents in various solvents. The Microspec consists of an IR light source, a detector with a
filter that isolates a specific IR wavelength, and a transmission flow cell.


Components: Chlorine; ferrous tetrachloride
Range: 0-50 ppm (Cl2); 0-100 ppm (FeCl3)

The OMA-300 is a diode-array fiber-optics process spectrophotometer, continuously measuring a high resolution (190-800 nm at 1 nm resolution) spectra of the sample. The absorbance signals are correlated to concentrations via a multi-wavelength

FeCl3 is an efficient catalyst in the direct chlorination of ethylene, the reaction in which ethylene and chlorine are dissolved and combined
to form EDC:

C2H4 + Cl2 -- > C2H4Cl2

While FeCl3 is extremely useful in producing EDC, its presence in the product is highly undesirable. EDC which has not been washed of all its FeCl3
threatens to clog the cracking furnace, the instrument which heats and breaks EDC down into dry hydrogen chloride and vinyl chloride monomer (which is then polymerized to create PVC).

Monitoring the level of ferrous tetrachloride in EDC is thus of critical importance in protecting against fouled mechanisms.

Both FeCl3 and free chlorine can potentially pollute the EDC product. PVC made from impure EDC has different characteristics which make it less useful than high-quality PVC. Maintaining EDC purity is imperative if the product is not to be
compromised, and such quality assurance necessitates monitoring of both components.
AAI's innovative multicomponent analysis makes such monitoring possible. While conventional analyzers struggle with measuring interfering components like Cl2 and FeCl3, the OMA-300 is specifically designed for selectivity and accuracy in such scenarios.

29 Domino Drive
Concord, MA 01742
Tel: 978-287-4222
Fax: 978-838-5222
e-mail: sales@a-a-inc.com

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