Chemistry of inorganic compounds – Sulfur or compound thereof – Elemental sulfur
Patent
1988-06-02
1990-12-18
Russel, Jeffrey E.
Chemistry of inorganic compounds
Sulfur or compound thereof
Elemental sulfur
C01B 1704
Patent
active
049785192
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE ART
The present invention relates to a process for producing elemental sulphur from gases containing hydrogen sulphide and sulphur dioxide.
PRIOR ART
Among sulphur production processes most extensively used are those which are based on the known Claus reaction: 800.degree.-1,400.degree. C.) or catalytically at a temperature within the range of from 20.degree. to 450.degree. C. The Claus process is catalytically effected usually in a packed bed of a fluid (granulated) catalyst (gamma-alumina, bauxites) at a temperature of 120.degree. to 450.degree. C.
The gases to be processed are introduced into the catalyst bed at a temperature of 120.degree.-400.degree. C. at the volume ratio of hydrogen sulphide and sulphur dioxide of 2:1, whereafter the gases containing the formed sulphur are withdrawn from the catalyst bed and cooled to condense sulphur. The Claus reaction is reversible and, within the given temperature range, exothermal. The equilibrium degree of conversion of the starting gases into sulphur increases with lower temperature. However, at decreasing temperature condensation of sulphur in the catalyst bed is possible thus resulting in deactivation of the catalyst and slowing-down of the process.
When the process is conducted at a temperature above the dew point of sulphur (over 230.degree.-250.degree. C.) /cf. "Khimicheskaya Promyshlennost" Journal (Chemical Industry), 1965, No. 3, Yu. N. Brodsky, Preparation of sulphur from concentrated hydrogen-sulphide gases, p. 34 /, the equilibrium degree of conversion is not high, wherefore it is necessary to carry out the Claus reaction in several parallel catalyst beds--at least two of them, with cooling of the starting gases and condensation of the resulting sulphur between the catalyst beds followed by heating of gases to the reaction temperature. However, for this process it is necessary to use a large volume of the catalyst and many pieces of heat-exchanging equipment. The process incurs high operation costs connected with high hydraulic resistance of the unit in which the process is conducted and considerable power consumption for preheating of the gases between the catalyst beds. The process efficiency is low--in the case of two beds of catalyst the degree of conversion of the starting gases into sulphur does not exceed, as a rule, 94%.
When the process for producing sulphur is conducted at temperatures below the dew point of sulphur (cf. Sulfreen-Hydrocarbon Processing, 1979, v. 58, No. 4, p. 140), it becomes possible to reach a high degree of conversion (up to 99%) of the starting gases into sulphur in single bed of a catalyst; however, in this case it is necessary to regenerate the catalyst from time to time by evaporating sulphur condensed thereon by means of a stream of a hot regenerating gas. This process necessitates substantial power consumption for regeneration of the catalyst and has a low efficiency of processing of gases with a total volume concentration of sulphur compounds of above 2-3%.
Known in the art is a process for producing elemental sulphur (U.S. Pat. No. 4,303,402), wherein the process is conducted in two catalyst beds arranged in series so that into the first (along the path of the gases) catalyst bed the starting reaction gases are fed at a temperature below the dew point of sulphur, then the gases leaving this catalyst bed are heated and fed into the second catalyst bed at a temperature above the dew point of sulphur for evaporation of sulphur condensed thereon. As the second catalyst bed is freed from sulphur, the heating of gases between the catalyst beds is stopped and with a complete deactivation of the catalyst in the first bed the direction of the gas supply into the catalyst beds is reversed. This prior art process has a disadvantage residing in a low degree of conversion of the starting gases into sulphur upon increasing concentration (above 2% of H.sub.2 S) and at an elevated moisture content of the starting gases.
Also known in the art is a process for producing sulphur (U.S. Pat. No. 4,315,904), wherein
REFERENCES:
patent: 4303633 (1981-12-01), Thomsen
patent: 4309402 (1982-01-01), Al-Muddarris
patent: 4315904 (1982-02-01), Lell et al.
"CBA", Hydrocarbon Processing, Apr. 1979, p. 134.
"Sulfreen", Hydrocarbon Processing, Apr. 1979, p. 140.
Eremin Oleg G.
Malakhova Irina V.
Matros Jury S.
Zagoruiko Andrei N.
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