Design Guidelines for Distillation Columns in Fouling Service

Hydrocarbon Producers are exploring avenues to extend the on-stream time between outages for maintenance. Key equipment that can determine the end of run includes: catalyst life, cyclone erosion, and compressor and tower fouling. Critical equipment that has been shown to be a limiting factor can be duplicated to extend run length: for example parallel pumps, reactors and reboilers. This is a successful method to extend on-stream time, expensive and in fact, at times cost prohibitive. Incorporating design guidelines that increase the on-stream time of the key pieces of equipment is a better economic decision for most plants. Currently Refiners are planning four-year run lengths and Ethylene Producers greater than five-year run lengths. These targets present challenges for distillation column design. Potential problem areas include refining vacuum wash oil beds, ethylene plant quench and saturator towers, and butadiene and other polymer producing distillation columns. Each of these applications has some common characteristics. A review of successful and not so successful designs can help develop key design criteria. Design guidelines developed from successful applications can improve the on-stream time of each of the applications.