(78c) Liquid Heater Upgrade for Improved Operation with Ethane Feed

Shale gas development has led to the processing of large volumes of ethane feed in Crackers that were designed for heavier feeds. This can result in some significant operational challenges for cracking furnaces that were originally designed to process significant quantities of liquid feedstocks.

Four Naphtha cracking furnaces had previously been upgraded to increase capacity and to allow for the cracking of NGL feeds. The basis for this conversion included a design case for ethane feed but processing of that feedstock was not required until recently. The furnaces have experienced short run times on ethane feed and this is primarily driven by pressure drop in the cracking tubes. The end of run constraint is governed by maintaining appropriate pressure ratios across the critical flow devices that establish equal flows to each tube. These furnaces were found to have a very narrow operational window for pressure when cracking ethane feed due to the focus of their design optimization being towards other feedstocks.

This paper will discuss the upgrading of a Naphtha/Butane/Propane furnace to increase the operational window with ethane feed and to ensure considerations are included to properly integrate the operation with future Cracker debottlenecking plans.