Published October 2023
An improved sour water stripping (SWS) process can effectively remove impurities; however, the existing technology has several downsides and needs improvement for higher recovery efficiency and resalable commercial commodities, especially when the sour water is obtained from a refinery that processes heavy crudes (with high sulfur and nitrogen contents). This review covers the technology and economics of the sour water treatment process, a two-stage stripping column operation, developed by Chevron Corp. and later acquired by Bechtel Corp.
The sour water treatment process discussed in this evaluation is for a typical treatment plant with a capacity of 1,103,760 metric tons per year (t/y), treating sour water with a typical concentration of ammonia (NH3) at 2 weight percent (wt%), hydrogen sulfide (H2S) at 3.8 wt% and CO2 at 0.04 wt%. This sour water is treated in two stripping columns to provide two separate streams of products with high concentrations of NH3 and H2S. However, this review does not consider the additional processing of the NH3- and H2S-rich process streams.
This review emphasizes the economics, technology and process chemistry of an SWS process. Planners, manufacturers and designers looking for independent data for a two-stage SWS operation for NH3 removal may find it beneficial as a tool for cost estimation for varying plant capacities. It comprises the material balance, major equipment sizes and specifications, together with the process flow diagram. Cost data, including battery limits and off-sites, variable costs, capital expenditure, operating expenditure and overall process costs, is also presented.
The technological and economic evaluations of the process are the Process Economics Program’s (PEP) independent interpretation of a commercial process based on data produced internally, such as through Aspen HYSYS V12.1 simulation and equipment cost estimation. Although this assessment does not entirely correspond to the actual plant data, it is accurate enough to be used in the economic analysis of chemical process designs and adequately indicative of the process and process economics.