Black Liquor Enrichment with Petroleum Coke

摘要

Kraft paper mill energy costs may be significantly reduced by co-firing petroleum coke with black liquor, provided that the mill's recovery boiler has excess firing capacity and steam generation capability. Petroleum coke, a byproduct of petroleum refining with a relatively low cost per unit of energy, may be well suited for use in a kraft mill because it is more than 85% carbon with its major other element being sulfur. A number of recovery boiler technical issues were identified that were addressed in a recently completed laboratory study. Included are: good mixture uniformity and acceptable viscosity to enable conventional liquor spraying methods; minimal change in liquor swelling properties and combustion characteristics to maintain the proper balance between in-flight combustion and char bed reaction phenomena; acceptable disposition of sulfur; and purge of non-process elements via the green liquor dregs. Answers to these questions have been obtained in laboratory study mentioned above, conducted at IPST @ Georgia Tech using its Single Particle Reactor. Results have facilitated commercialization of the technology with a mill trial at a Southern kraft mill. Preliminary results of that trial have been summarized.