Challenges of Ethylene Process Compressor Trains: From Design to Start-Up and Operability

Abstract

This technical presentation features various challenges that a turbomachinery OEM and the end users face with compressor trains in Ethylene Process, from the initial design phase, to the plant commissioning and operation of these machines. The presentation illustrates also the possible technical solutions, such as special coatings to prevent fouling in charge gas compressors, to help end users to reduce the operating cost and risk of production loss. The implementation of compact solutions, which helps the charge gas and ethylene compressors to deliver a higher-pressure ratio in one casing, results in lower number of bodies with same compression sections and consequently simplified installation and lower costs. Technical and special design features will be illustrated during the presentation. A smoother operation of the units can be offered building a dynamic model capable to simulate the behavior of the drivers, compressors and process plant items, in stable operating conditions and transient phases. With such model, any potential criticality of the interactions between process and compressors can be identified up-front in a simulation environment, minimizing risks at site, during commissioning and first start-up. The impact of fouling on ethylene plant equipment can be substantial. The high possibility of gas polymerization occurring in the cracked gas compressor can lead to efficiency loss and unplanned outages with associated lack of production. An advanced stage-by-stage water injection system coupled with fully removable nozzles during compressor operation and an efficiency monitoring and control system, will reduce operating cost and risk of production loss by providing operators with continuously updated equipment performance. This information can also be integrated with the analytic that performs an early detection of steam turbine fouling phenomena. Finally, the authors present few case studies where the above strategies were successfully implemented.