Classifications

• • C—CHEMISTRY; METALLURGY
  • C01—INORGANIC CHEMISTRY
  • C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
  • C01B17/00—Sulfur; Compounds thereof
  • C01B17/02—Preparation of sulfur; Purification
  • C01B17/04—Preparation of sulfur; Purification from gaseous sulfur compounds including gaseous sulfides
  • C01B17/0404—Preparation of sulfur; Purification from gaseous sulfur compounds including gaseous sulfides by processes comprising a dry catalytic conversion of hydrogen sulfide-containing gases, e.g. the Claus process
  • C01B17/0452—Process control; Start-up or cooling-down procedures of the Claus process
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
  • Y10S—TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y10S423/00—Chemistry of inorganic compounds
  • Y10S423/06—Temperature control

Definitions

• the present invention relates to the oil and gas industries, and more particularly the liquid sulfur production units called CLAUS units.
• Petroleum desulfurization converts sulfur-containing organic compounds into H2S hydrogen sulfide, whose toxicity and ignition hazards are well known.
• H2S is also a constituent of natural gas, and it acts as a poison that deactivates the industrial catalysts used in natural gas recovery processes. It is therefore essential to convert hydrogen sulphide into non-toxic elemental sulfur and also a useful raw material. Indeed, the sulfur produced is generally of good purity, and can be sold as such or in the form of sulfuric acid H2SO4.
• the CLAUS process is generally a two-step process.
• a first combustion step is performed by burning a third of the H 2 S in a first chamber equipped with a boiler.
• one third of I 2 S 2 is partially oxidized to SO 2 by air and / or oxygen (I).
• This reaction (I) is complete and stops when all the oxygen is consumed.
• the sulfur dioxide SO2 thus formed reacts with remaining H2S to form sulfur gas and water according to the so-called CLAUS reaction (II).
• This reaction is balanced and the equilibrium constant depends essentially on the temperature.
• the overall chemical reactions involved are as follows: H 2 S + 3/2 O 2 -> SO 2 + H 2 O (I)
• reaction products are generally cooled in a condenser to recover, in liquid form, the elemental sulfur vapors that have formed in the combustion chamber and in the boiler.
• the unit generally comprises a series of catalytic reactors in series, each of them being associated with a gas heating system and a sulfur condenser.
• the CLAUS reaction being exothermic, the conversion to sulfur is favored by low temperatures. It is necessary, nevertheless, to maintain the temperature of the catalytic reactor at a sufficient level, not only to promote the kinetics of the CLAUS reaction, but especially to prevent the appearance of liquid sulfur dew on the surface of the catalysts, which would cause their deactivation .
• Tc in the present invention the set temperature imposed on the inlet of the catalytic reactor, noted Tc in the present invention, be adjusted so that the outlet temperature of the catalytic reactor, denoted Ts, is greater than the dew point temperature.
• sulfur at the outlet of said reactor, denoted Tr in the present invention This applies in fact to each of the catalytic reactors that the CLAUS unit can count.
• the adjustment of Tc is done in an empirical manner known to those skilled in the art, so that Ts takes the desired value.
• the dew point of sulfur is unknown because it depends, among other things, on the composition of the gas, which changes as it goes along. This is why one generally proceeds to a temperature adjustment Tc to a much higher level, to have a margin of safety as to the temperature of appearance of this dew point.
• the set temperature is thus generally adjusted so that the temperature Ts has several tens of degrees Celsius more than the expected temperature Tr at the exit of this same reactor.
• This technique has the major disadvantage of being disadvantageous from an economic and environmental point of view because, since the operation of the unit is not optimized, the conversion rate to sulfur is not satisfactory enough, which results in waste gases charged with acid gases (more particularly with H2S and SO2) requiring a greater complementary treatment.
• the invention provides a catalytic process for treating a mixture of HbS and SO2 to produce liquid sulfur, said process comprising the following steps: a) at least one step of heating at a temperature Tc of the mixture containing SO2 and I2S, b) at least one step of catalytic reaction of the heated mixture obtained in a) in the presence of at least one catalyst and at least one step of recovering the output mixture containing sulfur gas, c) at least one step of transforming the sulfur gas contained in the exit mixture obtained in step b) into liquid sulfur, said process being characterized in that, between step b) and step c), the temperatures Ts of said mixture of output and sulfur dew tr gaseous content in said output mixture is measured, and in that the heating temperature Tc of step a) is adjusted so that the temperature Ts is greater than that of dew Tr from 5
• the invention has several advantages, including optimizing the operation of the CLAUS unit and reducing the amount of untreated residual sulfur species, in particular H2S and SO2.
• the size of the additional waste gas treatment units is also optimized, resulting in additional energy and cost savings.
• the invention is not only applicable to new units, but also to pre-existing units, which can significantly reduce the operating costs of maintenance of the latter.
• the heating temperature Tc of step a) is adjusted so that said temperature Ts is greater than that of dew Tr from 5 0 C to 20 0 C, and more advantageously from 5 ° C to 10 0 C .
• this process is such that it is carried out in at least one CLAUS catalytic unit reactor, and preferably in at least two CLAUS catalytic reactor units.
• the device for implementing the method according to the invention comprises a calorimetric or magnetic probe.
• a CLAUS unit comprising a thermal stage (Eo) and three catalytic stages (E 1 , E 2 , E 3 ). serial.
• the first stage of combustion of I ⁇ 2S takes place in a first chamber equipped with a boiler 1.
• a third of I ⁇ 2S is partially oxidized to SO2 by air and / or oxygen.
• Sulfur dioxide SO2 thus formed reacts with remaining H2S to form gaseous sulfur and water according to the so-called CLAUS (II) reaction.
• the combustion products are cooled in a condenser 2 to recover, in liquid form, sulfur vapors element which formed in the combustion chamber and in the boiler by line 9.
• a catalytic first stage section (Ei) comprises heating the gas
• the sulfur is recovered in the liquid state by condensation after each reaction step by the lines 8, 8 'and 8 "corresponding to the reactors 4, 4' and 4".
• the invention is implemented in at least one of the reactors 4, 4 'or 4 ".
• the method according to the invention is such that it is implemented in one, two or three
• the recovered sulfur can be stored either in liquid form in tanks maintained at 140 ° C. or in solid form in a tank 6.
• all the residual sulfur components leaving via a line 7 after passing through the condenser 5 " these are either directed to a waste gas treatment unit, or converted to SO2 before their discharge to the atmosphere.
• the essential characteristic of the process according to the invention is that it measures the temperature Ts of the output mixture of a catalytic reactor implementing step b) and the dew point temperature Tr of the sulfur gas contained in said output mixture, and the heating temperature Tc is adjusted so that the temperature Ts is greater than that of dew Tr, from 5 ° C. to 30 ° C., and advantageously from 5 ° C. to 20 ° C., and more advantageously by 5 ° C. at 10 ° C.
• this process is such that it is implemented in at least one catalytic reactor of the CLAUS unit.
• the process according to the invention is such that it is implemented in at least two catalytic reactors of the CLAUS unit.
• the first catalytic reactor generally operates at a sufficiently high temperature to promote the hydrolysis of compounds such as COS and CS2.
• the present invention does not exclude an embodiment according to which the process is such that it is used in all the catalytic reactors of the CLAUS unit.
• the invention also relates to a device for carrying out the catalytic process according to any one of the preceding claims, intended to treat a mixture of H2S and SO2 to produce liquid sulfur, said device comprising the following means: at least heating means at a temperature Tc of the mixture containing SO2 and I ⁇ 2S; at least one means for catalytically reacting the heated mixture obtained at the outlet of the heating means in the presence of at least one catalyst and at least one means for recovering an exit mixture containing sulfur gas; at least one means for transforming the sulfur gas contained in the liquid sulfur output mixture, said device being characterized in that it makes it possible to measure the dew point temperature of the sulfur.
• said device comprises a calorimetric probe.
• said device comprises a magnetic probe.
• a typical method of dew point measurement is to cool an appropriate surface until dew occurs, to detect the time of dew, then to measure the temperature corresponding to the moment of the first dew. appearance of the dew deposit.
• Different devices manual or automatic, measure the dew point temperature. They can use a calorimetric, magnetic, optical or capacitive detection to follow the dew on this surface.
• Patent EP 542 582 describes certain embodiments of such a probe for measuring the dew point.
• the dew-point measuring device according to the method of the invention is a calorimetric or magnetic probe for measuring the dew point.
• the setpoint temperature for the 1st catalytic stage is set so that the outlet temperature of the first reactor 4 be equal to 31O 0 C.
• the dew point temperature is measured at the outlet of the 4 'and / or 4 "catalytic reactor (s), and the temperature (s) are adjusted. (s) Setpoint heaters 3 'and / or 3 ".
• the condenser 2 is set at 170 ° C while the condensers 5, 5 'and 5 "are set at 135 ° C.
• Example 1 In a first step, only the set temperature of the second reactor 4 'is adjusted so as to vary the margin between the outlet temperature of the second reactor and the dew temperature measured at its outlet.
• an adjustment of the second heater 3 'at 244 ° C. corresponds to a dew point margin of 60 ° C. at the outlet of the second reactor.
• a different setting with a margin of 5 ° C, for example, relative to the dew point would lead to setting the temperature of the second heater to 190 ° C and reduce SO2 emissions by 31, 1% by an overall efficiency of 98. , 4%.
• the residual charge to be processed in the tail gas unit is reduced from 1.94 T / d to 1.34 T / d.
• both the set temperature of the second and the third reactor are adjusted so as to vary the margin between the outlet temperature of these reactors and the measured dew point temperature.
• Table 3 groups the results obtained.

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• Chemical & Material Sciences (AREA)
• Organic Chemistry (AREA)
• Engineering & Computer Science (AREA)
• Automation & Control Theory (AREA)
• Chemical Kinetics & Catalysis (AREA)
• Inorganic Chemistry (AREA)
• Treating Waste Gases (AREA)
• Exhaust Gas Treatment By Means Of Catalyst (AREA)
• Devices And Processes Conducted In The Presence Of Fluids And Solid Particles (AREA)
• Catalysts (AREA)

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• 2006
  • 2006-02-27 FR FR0601691A patent/FR2897860B1/fr not_active Expired - Fee Related
• 2007
  • 2007-02-19 JP JP2008556810A patent/JP5259427B2/ja not_active Expired - Fee Related
  • 2007-02-19 US US12/279,297 patent/US7780942B2/en not_active Expired - Fee Related
  • 2007-02-19 EP EP07731009A patent/EP1989142A2/de not_active Ceased
  • 2007-02-19 WO PCT/FR2007/000298 patent/WO2007096512A2/fr active Application Filing
  • 2007-02-19 CA CA2641424A patent/CA2641424C/fr not_active Expired - Fee Related
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• 2008
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