(145b) Removal of Black Powder and Other Contaminants in LPG/LNG Furnace Feeds

Hydrocarbon feedstock (gas, supercritical fluid, or liquid) to ethylene crackers may contain significant levels of corrosion products, or water and salts. Iron Oxides/Sulfides and Sodium are well known coke promoters. They reduce the run length of the furnaces, which results in loss of ethylene production, shortened furnace tube life, higher maintenance costs, and undesirable side products such as CO in cracked gas.  The term “black powder” is applied to corrosion products widely prevalent in pipelines that transport natural gas and hydrocarbon feedstocks.  If there is black powder in a pipeline, then pigging operations will aggravate the problem.

Many separation technologies have been employed to remove solids from the pipelines but they suffer from poor performance in this demanding application. This paper discusses the use of highly efficient, longer lasting filters that have been extensively used in the Middle East in recent years to mitigate black powder issues.  The paper also discusses a recent commercial filter design that incorporates a two stage separation with a high performance cyclone and particulate filters in certain cases.  The presence of liquid water in the pipelines carrying gas is also detrimental to the process.  Liquid/gas coalescers containing proprietary surface treated materials have been employed to remove this contaminant.