Solvents for aromatics extraction have to meet a number of requirements whose effect on the economics of the process is discussed in detail. Experimental studies with a view to finding suitable solvents showed that the combination of two solvents will yield almost ideal solvent mixtures under specific conditions. These conditions and the inter-relationships were investigated. It was found that the properties of such solvent mixtures are in some cases better than it could be expected according to the mixing rule. The optimum solvent mixture was selected under particular consideration of capital investment and operating cost of the process. The solvent combination of N-methylpyrrolidone and ethylene glycol very well meets the requirements.
A modification of the existing AROSOLVAN extraction process using N-methylpyrrolidonelethylene glycol instead of N-methylpyrrolidonelwater as solvent was developed and tried out.
Les solvants nécessaires à l'extraction d'aromates doivent remplir plusieurs exigences, l'influence desquelles sur la rentabilité du procédé est discutée plus en détail. En cherchant des solvants convenables, on a trouvé qu'en mélangeant deux solvants sous certaines conditions on peut obtenir un mélange de solvant bien utilisable. Les conditions et normes de telles combinaisons de solvants ont été examinées. Il s'est démontré qu'un mélange de solvant obtenu de la sorte peut avoir des propriétés meilleures que celles auxquelles on devait s'attendre d'après les règles de mixtion. Pour choisir le solvant le plus favorable la rentabilité du procédé est décisive compte tenu des frais d'investissement et de moyens de service. La combinaison des solvants N-méthylpyrrolidon et glycol d'éthylène remplit les très bien exigences demandées.
On a élaboré et éprouvé une modification du procédé actuel AROSOLVAN avec emploi de N-méthylpyrrolidon - glycol d'éthylène au lieu de N-méthylpyrrolidon-eau.
After the Lurgi AROSOLVAN process7 for aromatics extraction had been applied in several commercial plants, Lurgi Gesellschaft fuer Mineraloeltechnik mbH carried out experimental work in its research laboratories with a view to improving and optimizing the process further.
This work required the performance of a lot of tests and calculations because any change of the process and in particular of the solvent with the aim of achieving an advantage also involves disadvantages. Detailed calculations therefore had to be made to find out whether the advantage outweighs the disadvantage under special consideration of the overall economics of the process, namely investment and operating costs. A general comparison of all known solvents was made on the basis of data published in literat~re~-~, 8-9, 16- 197 21, 24-25 and data derived from own experimental work. by E. MUELLER and G. HOEHFELD, Lurgi Gesells
