Abstract
The processing ratio of inferior and heavy oil has been increasing. With the much more stringent environmental regulations, hydrogenation process in the modern refinery has been more widely used. Hydrogen as necessary utility in the modern refinery, accounted for a very high ratio in the cost of refining. How to achieve optimal design or retrofit of the refinery hydrogen network is one of the important problems faced by modern refineries. The refinery off-gas streams are typical hydrogen-rich gas streams and they are important hydrogen sources. In addition, certain refinery off-gas streams are rich in light hydrocarbons, which are highly valuable raw materials for downstream chemical processes, such as ethylene cracking. Worthy to mention, once the light hydrocarbons in the refinery off-gas streams are recovered, the hydrogen in the remaining gas stream is enriched as new hydrogen source with higher hydrogen purity. Thus, the design or retrofit of refinery hydrogen network integrated with light hydrocarbons recovery offers much more possibilities for maximum usage of hydrogen. This paper aims to investigate the systematic approach for the optimal retrofit of refinery hydrogen network integrated with light hydrocarbon recovery. The retrofit of an industrial refinery hydrogen network is applied to illustrate the approach in detail. The results show that the benefit of the retrofit scheme with light hydrocarbons recovery reaches 6.24 M/y, and the investment payback period is merely 8 months.
