Fouling in the hot section of the separation train is widely recognized as a major challenge for successful, long-time operation of gas crackers. Root causes for fouling can be of very different kinds and are consequently hard to determine at first sight. As for the causes, mitigation measures applied in plant operation are also very diverse, ranging from chemical and wash oil injections to targeted management of recycles and small revamps. It is hence of utmost importance to know when to apply which measure.
Process simulation has become an essential tool for the design of new plants, allowing precise prediction of the separation steps. In the present paper, we will show how Linde uses process simulation for understanding root causes of fouling in operating plants and for developing suitable mitigation measures. Although hot section fouling is of high physical and chemical complexity, we have developed a pragmatic approach to evaluate and compare fouling risks and quantities in the water quench and charge gas compressor sections. The methodology has been successfully applied during a recent case study for an existing plant experiencing fouling in charge gas compressor intercoolers and suction drums.
These improved tools can thus be used to solve actual fouling issues, but also to prevent future problems, for instance before proceeding to a feed change. With Linde's experience, it is possible to anticipate potential fouling risks and to develop mitigation strategies in advance. The developed prediction methods are similarly used for the design of new plants.
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