Chevron WWT process

Figure 13 Chevron WWT process. Acid is used in first stage to enhance hydrogen sulfide removal. Caustic is used in second stage to enhance ammonia removal. (From Ref. 20.)...

Types of Processes, 296 Water Scrubbing, 297 Sour Water Stripping Process, 302 Ammonium Salt Production, 308 Phosam and Phosam-W Processes, 311 Chevron WWT Process, 314... 

Although small quantities of sour water may be disposed of by injection into deep wells or by adding to the plant waste water disposal system, these are not viable options for most plants. Normally the sour water is either processed in a sour water stripper (SWS), which produces a vapor phase containing both ammonia and acid gases, or it is selectively stripped in a two-colunon system such as the Chevron WWT process, which produces separate ammonia and hydrogen sulflde-rich gas streams. 

As shown in Figures 4-22 and 4-23, the Chevron WWT process incorporates the following steps ... 

Figure 4>23. Chevron WWT process ammonia recovery options. Rm Bea etal. (1983)...

The production of anhydrous or aqueous ammonia requires that the ammonia stripper overhead stream be further purified to remove H2S. Two steps of water scrubbing are required for the production of anhydrous armnonia, while the production of aqueous ammonia may be accomplished with either oite or two stubbing stq>s dqtmiding on the desired product purity. T cal product specifications for the Chevron WWT process are givmi in TaUe4-12. 

Table 4-12 Typical Product Specifications Chevron WWT Process ...

Chevron WWT Process Economics Amnwnia Incineration vs. Ammonia Recovery... 

Chevron WWT [Waste water treatment] An integrated process for treating sour water from oil refineries, particularly for removing ammonia, hydrogen sulfide, and carbon dioxide. Only physical processes are used—volatilization and condensation under various conditions. Developed by Chevron Research Company and used in 14 plants worldwide in 1985. Martinez, D., in Chemical Waste Handling and Treatment, Muller, K. R., Ed., Springer-Verlag, Berlin, 1986, 180. 

Chevron s WWT (wastewater treatment) process treats refinery sour water for reuse, producing ammonia and hydrogen sulfide [7783-06-04] as by-products (100). Degassed sour water is fed to the first of two strippers. Here hydrogen sulfide is stripped overhead while water and ammonia flow out the column bottoms. The bottoms from the first stripper is fed to the second stripper which produces ammonia as the overhead product. The gaseous ammonia is next treated for hydrogen sulfide and water removal, compressed, and further purified. Ammonia recovery options include anhydrous Hquid ammonia, aqueous Hquid ammonia, and ammonia vapor for incineration. There are more than 20 reported units in operation, the aimual production of ammonia from this process is about 200,000 t. 

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