(191d) Ethylene Cracker Capacity Increase and Modernization

The authors present a case study for the expansion of an ethylene cracker and how equipment and process modernization can play an important role in developing the project scope.

The case study cracker was commissioned in 1977 as a 455 kTA naphtha cracker. Over the years, since the plant was brought on line, the plant capacity has been increased to 160% of the original design, through the addition of cracking heaters, retrofit of equipment and allowing feedstock flexibility. The cracker has the capability to crack ethane, propane, C4's, naphtha, Heavy Atmospheric Gas Oil (HAGO) and Vacuum Gas Oil (VGO) as individual feed streams.

With a future demand increase for ethylene, a further expansion of the facility was proposed to increase the ethylene production capacity by 180 kTA. Initially the additional cracking capacity was to be obtained through the addition of more cracking heaters. In the early stages of the project development a proposal was made to investigate the value of modernizing equipment for higher capacity versus adding additional equipment.

This case study focuses on the area of the cracking heaters in the overall project development. It highlights the value and benefits of modernizing equipment - including a new coil design - versus adding additional equipment. The design challenges are discussed as well as opportunities for improvements in capacity, efficiency, and reduction of emissions. Some highlights of the construction and initial operation are also reviewed. Finally the performance of the modernized heaters will be compared to the performance of the heaters before modifications, to quantify the value of modernizing the cracking heaters.