Cracker Control On-Line Process Chromatographs Optimize Fine Chemicals Production

| Editor: Dr. Jörg Kempf

Exact and reliable chemical analysis of feedstocks and products is very important in the manufacture of fine chemicals. Laboratory gas chromatographs are among the techniques traditionally used for this task, but pressure to improve process operations has brought change. Online process gas chromatography now provides significant benefits, as shown on a naphtha cracker.

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Naphtha cracker of Lonza in Visp (Picture: Lonza)
Naphtha cracker of Lonza in Visp (Picture: Lonza)

Fine chemicals are widely used as intermediates and additives in the pharmaceutical, vitamin, food and fertilizer sectors, as well as for dyes, adhesives, fragrances, plastics, for pest control, and in animal feedstuffs. A global player in this sector is Lonza , whose largest production location is in Visp, Switzerland. Production starts with a naphtha cracker which provides ethylene, hydrogen, methane and carbon dioxide. The multi-product plant uses this raw gas as feedstock to make fine chemicals including niacin (vitamin B3) and intermediates for the production of vitamins A and E.

To guarantee product quality, Lonza relies on gas chromatography (GC) to analyze both the feedstock and the raw cracked gas. The company traditionally used laboratory instruments for this task, with an inevitable delay in processing samples and returning the results to the control room. Now, on-line GCs are increasingly used to provide direct process control, and such an arrangement has certainly worked well at Lonza.

Highly integrated plant

The Visp plant dates back to 1915, when acetylene from calcium carbide was used as a feedstock for basic chemicals. In the 1960s the pyrolysis of naphtha replaced the use of acetylene.