Caprolactam, or ε-Caprolactam to be precise, which is produced by the megaton every year worldwide, is mainly used as a base material in the manufacture of polyamide-6 fibres (brand name Perlon). Almost all of the industrial manufacturing processes today take place using cyclohexanone as the intermediate stage and can be roughly divided into three steps:
First, the cyclohexanone is produced from aqueous ammonia and benzene. Next, the cyclohexanone can be converted to the base substance cyclohexanone oxime using hydroxylamine and sulphuric acid. This reacts in another process step in the presence of sulphuric acid and oxime through the Beckmann process to become ε-Caprolactam (raw caprolactam). This must then be separated from the ammonium sulphate phase. Hydrogenation in the presence of von Raney nickel noticeably increases the caprolactam yield. The next process stages involve purifying and concentrating the caprolactam monomer by extraction, distillation and crystallisation.

The complexity of the caprolactam production process demands optimal process control so that both the quality requirements for the manufacture and maximum plant productivity are guaranteed. KROHNE offers a tried-and-tested range of measuring equipment for maximum performance requirements. In addition, the process conditions in caprolactam manufacturing now face additional challenges because of increasing environmental requirements with fewer greenhouse gases, lower energy input and salt-free routes. This requires continuous and precise monitoring of the process parameters such as pressure, flow and temperature. KROHNE's devices from the OPTIBAR, OPTIMASS, OPTIFLUX and OPTITEMP ranges ensure this. They generate valid realtime information for the process control system, are impressively sturdy and work reliably even with highly aggressive media such as sulphuric acid. KROHNE systems can thus guarantee reliable operation of the caprolactam plant.