Effect of Steam and Carbon Dioxide on Naphtha Cracking to Mitigate Cracked Gas Compressor Fouling, Coke Accumulation and Energy Resources

Abstract

The naphtha cracking process experiences problems such as fouling in the cracked gas compressor, and the accumulation of coke on the furnace coils, which require the use of exhaustive energy resources and costs to maintain the process. Several attempts have been carried out to solve this process in ethylene plants, but reducing fouling and energy costs during naphtha cracking remains a challenge. This study involves a simulation experiment that covers the addition of steam and carbon dioxide to the naphtha cracking process based on real-world data extracted from an ethylene plant in Libya, in order to investigate the effects of the addition of CO2 towards mitigating fouling in the cracked gas compressor, as well as coke accumulation on the coils inside the furnace, and in turn the energy resources and costs involved in the process. The key role of the addition of steam is the fractional elimination of the accumulated coke that leads to various issues within the reactor, such as the low heat transfer and the decrease in pressure. In this study, the diluting media CO2 is employed along with steam in order to investigate its effect on operating conditions and the main products’ yields. Two simulation models were constructed to investigate the thermal cracking process of ethylene in the existence of CO2 and steam. The first model involved only steam, and represented the standard design. The second model involved the addition of both CO2 and steam. After evaluation and comparison of both models, promising results reveal that the addition of CO2 and steam during the naphtha cracking process mitigate costs and energy resources required to maintain the operation, as well as achieve higher yields of ethylene, propylene, methane and hydrogen. The run time of the furnace and reactors was also increased.

Keywords: naphtha cracking, cracked gas compressor, coking