Sulfreen process

Hydrosulfreen A process for removing sulfur compounds from the tail gas from the Claus process. It combines the Sulfreen process with an upstream hydrolysis/oxidation stage, which improves efficiency and optimizes the emission control. Developed jointly by Lurgi and Societe National Elf Aquitaine, and installed in 1990 in the Mazovian Refining and Petrochemical Works, near Warsaw, Poland. See also Oxysulfreen. 

These sub-dew point processes can increase the overall Claus plant sulfur recovery to up to 99%, as limited by equilibrium conversion and sulfur vapor pressure losses. Elf Aquitaine s Sulfreen process, Amoco s cold bed adsorption (CBA) process, and the Mineral and Chemical Resource Company (MCRC) process licensed by Delta Hudson are all variations on the cold bed sub-dew point process. 

Figure 25.4 shows a typical sulfur recovery plant based on the Claus process. The tail gas from the Claus reactors may be further processed to remove any remaining sulfur compounds. Combined H2S removal efficiencies of 99.5-99.99 percent are achievable.20 This may be done by low-temperature Claus-type solid-bed processes (e.g., the Sulfreen process), wet-Claus absorption/oxidation processes (e.g., the Clauspol 1500 process), or hydrogenation of the off-gas to form H2S for recycle (e.g., the SCOT process). Residual sulfur compounds in the tail gas are then incinerated to S02. The residual S02 in the oxidized tail gas may be scrubbed by any of several processes (e.g., the Wellman-Lord process) before being vented to the environment. It is feasible to bring the H2S content of... 

DOXOSULFREEN A process for oxidizing hydrogen sulfide to elemental sulfur, based on the SULFREEN process and catalyzed by copper on alumina. Use of a fairly low temperature (90 to 140°) minimizes the further oxidation to S02. Developed by Elf and Lurgi. 

MAXISULF A process for removing sulfur from tailgases from the Claus process. It combines an adsorption stage with the Sulfreen process. Developed and offered by Lurgi. 

The first class of systems is illustrated by the Sulfreen (80, 81, 82) and IFP (83, 84) processes. In the Sulfreen process the Claus reaction takes place on the carbon or alumina catalyst in a fixed-bed reactor. At the reduced temperature, the conversion equilibrium is improved, but the sulfur is retained on the catalyst as a liquid and must be removed by... 

The LURGI Sulfreen Process is very similar to the Claus process and can be conveniently combined with it. Its major difference lies in the lower operating temperature which ensures that the sulfur recovered over the catalyst is simultaneously adsorbed by it. 

Fig. 5.13. Sulfreen process combined with Claus unit, (a) Reactor (b) heat exchanger (c) sulfur condenser (d) separator (e) blower... 

The gas leaving the hydrogenation reactor is first cooled in a waste heat boiler to about 170°C and then in a quench cooler to approximately 35°C. The quenching operation uses circulating water from which the heat is removed in a cooler. Unlike the Sulfreen process described above, this process produces condensate as the gas is cooled below the steam dew point this condensate has to be withdrawn from the water loop and fed to a stripper to remove H2S. A blower delivers the almost dry gas from the quench cooler to an absorber to eliminate the hydrogen sulfide by means of an amine wash liquor. 

The first group includes - in addition to the Sulfreen process described in detail above - also the CBA (Cold Bed Adsorption Process) developed by Amoco Pro-... 

Sulfur is recovered from the sour gas streams from the Rectisol plants using the Claus process followed by the Sulfreen process for tailgas cleanup. 

Although the Sulfreen process is cyclic, alternating between sulfur adsorption and desorption, the use of several converters in adsorbing, desorbing, and cooling service permits continuous operation. 

Introduction, This process, which was developed by AMOCO Canada Petroleum Company. Ltd. in the early 1970s, has been described by Goddin et al. (1974). Nobles et al. (1977), Rccd (1983), and Lim et al. (1986). The Cold Bed Adsorption (CBA) process is a sub-dewpoint" sulfur recovery process and is quite similar in principle to the Sulfreen process, as the Claus reaction is al.so carried out at sufficiently low temperatures to cause condensation of sulfur on the catalyst. However, unlike the Sulfreen proce.ss, where a closed loop of inert gas is used to desorb the adsorbed sulfur, a hot gas slipstream from the Claus unit is used for this purpose. 

Guyot, G., and Martin, J. E 1971, The Sulfreen Process, paper presented at the Canadian Natural Gas Processors Association Meeting, Edmonton, Canada, June. 

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