INTRODUCTION

Raw crude oil contains sulfur and nitrogen. During processing, the sulfur and nitrogen are converted principally to H ₂S and NH ₃ and, to a lesser degree, organic sulfur (COS and CS ₂) and mercaptans (RSH).

More stringent environmental standards on the emissions of sulfur and nitrogen compounds, together with the low sulfur specifications for petroleum products, have resulted in making sulfur management critical within today s refinery. The importance of sulfur management cannot be overstressed. Today s refineries are processing crudes with higher sulfur contents and are doing more bottom-of-the-barrel conversion. The need for new or revamped sulfur management facilities is expected to grow as demands for cleaner fuels and environment increase and crude oil slates change.

As illustrated in Fig. 11.1.1, sulfur management within a refinery consists of four basic processes. Amine treating units (ATUs) remove H ₂S from recycle gas streams in hydroprocessing operations and from fuel gas/liquefied petroleum gas (LPG) recovery units. The amine is regenerated in one or more amine regeneration units (ARUs). Sour water strippers (SWSs) remove H ₂S and NH ₃ from the sour water streams. Sour water is the result of...