Sulfur scavenging processes

The catalytic oxidation of sulfur compounds in gas streams is the basis for numerous gas purification proce,s.ses, most of which are covered in other sections of this book. The oxidation of SO2 to SOj as part of a sulfur dioxide removal process is discussed in Chapter 7. The oxidation of HiS to elemental sulfur by the Claus process and related technologies is covered in Chapter 8. The liquid-phase oxidation of H2S to elemental sulfur is described in Chapter 9, and the oxidation of H S and other sulfur compounds in dry boxes and in other sulfur scavenging processes is included in Chapter 16. An area of technology that is not covered... 

Sulfur scavenging processes are typically batch operations. They make use of materials that capture and retain sulfur compounds, but have a finite effective capacity. When this capacity is reached, the spent sorbent (liquid or solid) must be removed and replaced with fresh material. The spent sorbent is normally disposed of as waste, and the production of an environmentally acceptable waste has become a key factor in the selection of. scavenging proces.ses for specific applications. Other important considerations are operating safety and reliability (unattended operation is often required) and, of course, capital and operating costs. 

Sulfur scavenging processes can generally be categorized as follows ... 

Solutions of alkylamitte/aldehyde condensation products have been used in several sulfur-scavenging processes. The spent solution is fiee of sulfur particles, and no nitrogen oxide gases are formed however, it has a very obnoxious odor. It is reported to have corrosion-inhibition properties and to be approved for Gass I, non-hazardous, deep-well disposal (Houghton and Bucklin, 1994). Examples of processes in this category are Gas Treat 114. Gas Treat 113. and Gas Treat... 

Scavenger processes are used only for trace sulfur removal and are in many cases not suitable for in-situ regeneration. They are typically designed with two or more vessels operating in a lead/lag mode. When the scavenger material reaches the end if its useful life, it must be removed from the vessel and anew charge loaded in. 

Uses Sulfur scavenger in lubricants improves antiwear and antifriction props. color/processing stabilizer for polymers ... 

Electrica.1 Properties. The electrical properties of SF stem primarily from its effectiveness as an electron scavenger. To accomplish electrical breakdown in a dielectric gas, primary electrons must gain sufficient energy to generate appreciable numbers of secondary electrons on molecular impact. Sulfur hexafluoride interferes with this process by capturing the primary electrons, resulting in the formation of SF or SF ions and F atoms (29) ... 

Miscellaneous. In ore flotation, sodium sulfite functions as a selective depressant. In textile processing, sodium sulfite is used as a bleach for wood (qv) and polyamide fibers and as an antichlor after the use of chlorine bleach. Synthetic appHcations of sodium sulfite include production of sodium thiosulfite by addition of sulfur and the introduction of sulfonate groups into dyestuffs and other organic products. Sodium sulfite is useful as a scavenger for formaldehyde in aminoplast—wood compositions, and as a buffer in chrome tanning of leather. 

All steels contain some Mn, and its addition in 1856 by R. Mushet ensured the success of the Bessemer process. It serves two main purposes. As a scavenger it combines with sulfur to form... 

Under some circumstances transport processes other than fluid motion and molecular diffusion are important. One important example is sedimentation due to gravity acting on particulate matter submerged in a fluid, e.g., removal of dissolved sulfur from the atmosphere by precipitation scavenging, or transport of organic carbon from the surface waters to the deep... 

Analyzers that measure C, H, and N, but not S, use catalysts that are better optimized for this process. The oxidation catalyst is Cr203. The gas then passes through hot Co304 coated with Ag to absorb halogens and sulfur. A hot Cu column then scavenges excess 02. 

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