As natural feed components do not contain enough sulphurous amino acids (cysteine/cystine and methionine), synthetic methionine has become a key element of modern animal nutrition. Essential amino acid ensures that pigs, chickens etc. can make better use of their food. Nowadays, industrially manufactured DL-methionine is usually produced by chemical synthesis in the widely used carbonate-hydantoin process. The process can be roughly divided into four stages: hydantoin production, hydantoin hydrolysis, DL-methionine production and filtration and drying. Firstly, the basic substances (including acrolein) are prepared from raw petrochemical substances in preliminary processes. The subsequent hydantoin production in the primary reactor is based on the intermediate product methylmercapto propionaldehyde (MMP), which is converted to a hydantoin derivative with ammonia, carbon dioxide and hydrogen cyanide, the alkaline hydrolysis of which results in an alkaline salt of the methionine. The end product, methionine, is the result of neutralisation with an acid such as carbon dioxide.

The raw materials and intermediate products for the methionine process must be available in the right quantity and quality as the plant runs round the clock every day of the year. This must be systematically monitored, as must the other process steps in and around the hydantoin reactors, allowing for the hygiene requirements of the end product. KROHNE provides a wide range of measuring devices for applications in fine chemistry such as methionine, from Coriolis mass flowmeters for maximum performance requirements and accuracy and programmable high-performance temperature transmitters to differential pressure transmitters with integrated absolute pressure measurement. These are ideal for hydrostatic level, interface, density or complex differential pressure process applications.