Sulphur Claus process

RSRP [Richards sulphur recovery process] A proposed modification of the Claus process in which liquid sulfur is used to cool the catalyst bed. Developed jointly by the Alberta Energy Company and the Hudson s Bay Oil Gas Company, but not reported to have been commercialized. 

SuRe [Sulphur recovery] A version of the Claus process in which the capacity of the plant is increased by using air enriched in oxygen in the production of the sulfur dioxide. There are two versions SURE SSB [Side Stream Burner], and SURE DC [Double Combustion], In the first, a small portion of the feed stream containing hydrogen sulfide is burnt sub-stoichiometrically in a second burner in the second, the hydrogen sulfide is oxidized in two stages, with cooling and sulfur separation between them. Both of these... 

After the absorber/stripper unit, in conventional operations the pure H2S is fed to a Claus unit where the H2S is converted to elemental sulphur and H2O. The Claus unit can be equipped with an after-treatment to enhance conversions. Another method to decompose H2S to less harmful compounds is the thermal dehydrogenation of H2S to hydrogen and sulphur. Both processes will be treated in detail in the remainder of this chapter. 

The most commonly used process for sulphur recovery from H2S is the Claus process. This process was developed by C.F. Claus in 1883 [3], LG. Farbenindustrie AG modified the process in 1936 to its current lay-out, including a thermal and a catalytic separation step [4],... 

Clausorb A process for removing residual sulfur from the tailgases from the Claus process. Sulphur, Jul-Aug 1999 (263), 53-54, 56. 

Kunkel, L.V., GPA H2S Removal Panel - Part 3, Claus Process Improvements in Sulphur Recovery, Oil and GasJ., 92-99 (August 7, 1978). 

Claus process A process for obtaining sulphur from hydrogen sulphide (from natural gas or cmde oU). it involves two stages. First, part of the hydrogen sulphide is oxidized to sulphur dioxide ... 

In the Claus process Sulphur Recovery Units, metallic bellow expansion joints in the tail gas line to Incinerator, seldom fail by developing crack on the bellow element due to various mechanical and metallurgical reasons. 

The physical wash processes can be designed so that H2S and CO2 are absorbed separately, meaning that both gases can be reeovered at high concentration. The CO2 stream may be compressed for CCS (refer to Section 1.4.2). The H2S stream is converted either into elementary sulphur by the Claus process or into concentrated sulphuric acid by the WSA process [291]. 

Sulphur compounds are normally converted to hydrogen sulphide during refining and this is converted to sulphur by the Claus process. The H2S is mixed with air in a combustion chamber where it is converted in part to SO2. 

The Claus process has been the standard of the sulphur recoveiy indushy, but limitations and problems relating to composition may restrict its effectiveness for fuel cell applications. Traditional Claus plant may be used for sulphur recoveiy from a rich feed gas stream, with at least 50% H2S by volume. However, for lower H2S content (5-50% volume) a modification of the traditional Claus plant is needed (McIntyre and Lyddon, 1997). In addition, acid gas feeds may contain undesirable components such as ammonia and hydrocaibons, which cause problems during processing. For an optimum conversion of H2S, a 2 1 H2S S02 ratio is required. The reactions involved in a Claus plant are as follows ... 

Claus process A two-stage process used for the removal of sulphur from natural gas or crude oil. In the first, hydrogen sulphide is partially oxidized using air to form sulphur dioxide. In the second, the sulphur dioxide is reacted with the hydrogen sulphide in the presence of a catalyst at 300°C to form elemental sulphur and water vapour ... 

Although at first sight, the Citrate Process may not appear to be in any way related to the traditional Claus, it is in fact an H2S/SO2 redox reaction in solution with the activating bauxite, carbon, or metal salt type catalyst replaced by a citrate complex with SO2. The chemistry of the process is clearly interesting and of some importance but for the purposes of this review it is sufficient to draw the analogy indicated above. The Citrate Process is yet another reduction process that may require the ancillary generation of H2S from natural gas and product sulphur if the effluent gas stream is solely SO2 as far as sulphur content is concerned. 

The H2S concentration in the tail gas of a conventional Claus plant is still some 5%. This H2S is normally incinerated to S02 and released to the atmosphere. Due to stricter environmental regulations a large number of new technologies based on Claus tail gas treatment have been developed to minimise the S02 exhaust from sulphur recovery units. The Superclaus process and the Shell Claus Off-Gas Treating (SCOT) process are treated below. For descriptions of other tail-gas processes, the reader is referred to [2],... 

The SCOT process provides an efficient way of removing sulphur-containing compounds from the tail gas of a conventional Claus reactor. The tail gas is heated to about 300°C and fed to a hydrogenation reactor, where all sulphur compounds in the gas are converted to H2S. Almost all H2S is removed in an absorber/stripper combination and fed back to the Claus plant. The off-gas from the absorber contains virtually no sulphur compounds (values as low as 500 ppm are reported [2]) and is incinerated in the Claus incinerator. A schematic diagram of the SCOT process is provided in Figure 2. 

Claus plant (including tail gas treatment) are of the order of 32/tonne exclusive of steam credit. Subtracting these costs from the totals in Table I, the overall net revenue from the Claus system would be 21.75/tonne of sulphur produced whereas that from the decomposition process would be 50.50 /tonne - a 230% difference. Even in the unlikely event that the total capital and operating costs for the decomposition process exceed those of the Claus system by 100%, the two processes are still approximately competitive. 

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