Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01D—SEPARATION
  • B01D53/00—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols
  • B01D53/34—Chemical or biological purification of waste gases
  • B01D53/46—Removing components of defined structure
  • B01D53/48—Sulfur compounds
  • B01D53/50—Sulfur oxides
  • B01D53/508—Sulfur oxides by treating the gases with solids
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01D—SEPARATION
  • B01D53/00—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols
  • B01D53/02—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols by adsorption, e.g. preparative gas chromatography
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
  • B01J20/00—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof
  • B01J20/02—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof comprising inorganic material
  • B01J20/04—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof comprising inorganic material comprising compounds of alkali metals, alkaline earth metals or magnesium
  • B01J20/041—Oxides or hydroxides
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
  • B01J20/00—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof
  • B01J20/30—Processes for preparing, regenerating, or reactivating
  • B01J20/34—Regenerating or reactivating
  • B01J20/3433—Regenerating or reactivating of sorbents or filter aids other than those covered by B01J20/3408 - B01J20/3425
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
  • B01J20/00—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof
  • B01J20/30—Processes for preparing, regenerating, or reactivating
  • B01J20/34—Regenerating or reactivating
  • B01J20/345—Regenerating or reactivating using a particular desorbing compound or mixture
  • B01J20/3458—Regenerating or reactivating using a particular desorbing compound or mixture in the gas phase
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
  • B01J20/00—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof
  • B01J20/30—Processes for preparing, regenerating, or reactivating
  • B01J20/34—Regenerating or reactivating
  • B01J20/3483—Regenerating or reactivating by thermal treatment not covered by groups B01J20/3441 - B01J20/3475, e.g. by heating or cooling
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01D—SEPARATION
  • B01D2257/00—Components to be removed
  • B01D2257/30—Sulfur compounds
  • B01D2257/302—Sulfur oxides

Definitions

• the present invention relates to the field of combustion and more particularly that of the regeneration of absorbents used to treat the products of combustion.
• French patent FR-2,636,720 filed in the name of the applicant discloses a boiler in which desulphurizing agents are injected into a specific zone, called the desulphurization chamber, interposed between the combustion chamber and the heat recovery zone by exchange convective.
• the desulphurizing agents provided in this installation are preferably non-regenerable calcium absorbents, such as lime or limestone, or industrial residues with a high calcium carbonate content (sugar scum, stationery scum, etc.).
• the regeneration of the absorbent can be carried out by means of a fluidized bed or possibly using a rotary kiln.
• the methods described above propose to use as regeneration gas a hydrogenated or hydrocarbon compound having a total carbon number less than 10 such as hydrogen, methane, ethane, propane, isobutane and / or a mixture of said gases.
• Hydrogen is the most suitable regeneration gas because it leads to the weakest coking of the absorbent.
• its supply on the industrial site, in refineries for example can be problematic. Indeed, hydrogen is not always available in sufficient quantity in refineries, in particular when the conversion and hydrodesulfurization operations are important there.
• the two aforementioned inventions which provide for regeneration of the absorbent require costly and numerous specific equipment linked to the regeneration step.
• the present invention makes it possible to eliminate the drawbacks and components of the prior installations while retaining the same regeneration yield.
• the present invention thus makes it possible to minimize the number of pieces of equipment necessary for the regeneration stage by proposing the partial combustion of the regeneration gas upstream of the regeneration and by combining the regeneration reaction by means of combustion, such as for example a burner, preferably located near the regeneration zone and the filtration of the absorbent.
• means of combustion such as for example a burner
• the proximity of the preheating means and the regeneration / filtration zone also makes it possible to limit the handling and transport of corrosive fumes containing for example hydrogen sulfide.
• the very nature of the regeneration gas makes it possible to increase the conversion rate of the regeneration reaction, as will be explained below.
• no recycling of the regeneration gas is necessary so that all the components linked to said recycling can be eliminated.
• the subject of the present invention is a process for the regeneration of spent absorbent originating from a desulphurization zone or of any gas containing sulfur oxides, said regeneration being simultaneous with filtering of said absorbent in a reducing atmosphere, in which one performs partial combustion of a regeneration gas upstream of said regeneration and the products of said partial combustion are mixed with the spent absorbent before the regeneration-filtration step.
• the method consists in mixing an additive regeneration gas during the regeneration-filtration stage.
• said regeneration gas comprises hydrogen sulphide.
• it comprises, alone or with hydrogen sulphide, a hydrocarbon.
• a hydrocarbon fraction into the regeneration gas allows the appreciable increase in the evolution of hydrogen during the partial oxidation of said gas and thus advantageously promotes the regeneration of the absorbent.
• the hydrocarbon used is for example methane. It is also possible according to the invention to operate with a hydrocarbon gas such as methane, at least a fraction of which is previously partially oxidized before being brought into contact with the spent absorbent, and which will thus generate a CO / H2 / C02 / mixture. H20 less coking for the absorbent than the hydrocarbon alone.
• the gases from the regeneration-filtration stage can be cooled. Additionally, the cooled gases can be sent to a Claus unit.
• the regenerated absorbent resulting from the regeneration-filtration step is mixed with a carrier gas and then sent to a storage unit.
• the regenerated absorbent is mixed with a carrier gas and then sent to a desulphurization zone.
• group VIII noble metals as regeneration catalyst, which are not only promoters of capture of sulfur dioxide by solid absorbents based, for example, on magnesium oxide, but also catalysts. of the regeneration reaction of the absorbents, such as for example the reduction of magnesium sulfate to magnesium oxide.
• the platinum group metals have the advantage of their strong catalytic activity, it is known to those skilled in the art that said activity decreases due to the degradation of such a catalyst at high temperature (greater than about 900 ° C.).
• high temperature greater than about 900 ° C.
• the sintering of the support as well as the sintering of the active phase and / or its encapsulation by the support are among those most commonly cited.
• the catalytic activity of a palladium-based catalyst oscillates between 800 and 1000 ° C due to the following balance:
• copper oxide and preferably cerium oxide have a very long service life. higher than that of the catalysts used in the prior art under the temperature conditions of said regeneration.
• copper oxide and / or cerium oxide are also not only promoters of capture of sulfur dioxide by solid absorbents based, for example, on oxide of magnesium, but also catalysts of the regeneration reaction of absorbents such as the reduction of magnesium sulfate to magnesium oxide.
• the regeneration is therefore carried out in the presence of a catalyst.
• the catalyst used for said regeneration step can comprise copper oxide and preferably cerium oxide.
• the used absorbent can be treated before it is mixed with the regeneration gas.
• This treatment can consist of a fractionation, carried out for example using a cyclone into at least two fractions, some of said fractions being rich in catalyst, the others being poor in catalyst.
• Said catalyst-rich fractions are preferably recycled to a desulphurization zone, and said catalyst-poor fractions are either directly sent to the regeneration zone, or advantageously separated into two streams, one being recycled to a desulphurization zone, the another being sent to the regeneration zone.
• the spent absorbent can be temporarily stored before being mixed with the regeneration gas.
• Another subject of the invention is a device for regenerating spent absorbent resulting from the treatment of smoke from a thermal generator comprising a regeneration means operating in a reducing atmosphere. by bringing a regeneration gas into contact with the spent absorbent, associated with a filtration means, said means comprising an inlet for the spent absorbent, an outlet for the gases, an outlet for the regenerated absorbent.
• the device further comprises a means for partial combustion of the regeneration gas and a means for mixing the regeneration gas with the spent absorbent, placed upstream of the spent absorbent inlet in the regeneration means. .
• the regeneration means can comprise an additional inlet for a regeneration gas.
• the device comprises a means for cooling the gases leaving the regeneration means, the inlet of which is connected to the outlet of the gases.
• the cooling means may include an outlet connected to an inlet of a Claus unit.
• the device according to the invention further comprises a filtration means intended to separate the spent absorbent from the effluents at low temperature (T ⁇ 500 ° C) and before their entry into the regeneration-filtration means, said means being arranged upstream of the regeneration means relative to the direction of flow of the absorbent.
• the device according to the invention comprises a means intended for storing the spent absorbent, disposed upstream of the entry of spent absorbent in the regeneration means.
• the reference 1 indicates a dust collector through which the exhaust fumes from a boiler or an oven or from any thermal generator which specifically burns liquid or gaseous sulfur fuels are filtered.
• FR 2 671 855 can thus constitute the inlet of the filtering element 1.
• the outlet of any other means generating polluted effluents and equipped with the same means for desulphurizing the fumes can of course constitute the inlet of the element 1.
• the dust collector 1 not essential however for the proper functioning of the invention, makes it possible to carry out a first separation between the fumes which exit through a chimney 2, and the spent absorbent having captured the sulfur oxides.
• the used absorbent is evacuated by gravity from the filtration means 1 by specific lines 3 and 4. Valves 5 and 6 or any other equivalent means placed on lines 3 and 4 can temporarily store the used absorbent in the 'Element 1.
• a single discharge line 4 of the used absorbent can be provided without departing from the scope of the invention.
• a carrier fluid can be mixed with the spent absorbent in order to ensure its pneumatic transport.
• one of the discharge lines for the spent absorbent (line 3) is used to recycle part of the absorbent to the boiler.
• a line 4 is provided for transporting all or part of the absorbent to a storage hopper 9 which serves as a buffer for decoupling the operation of the regenerator from that of the thermal generator.
• This hopper also serves to increase the seal between the smoke circuit (oxidant) and that of the regeneration gas (reducer), avoiding the passage from one to the other. This reinforces the safety of the device by avoiding the risks of self-ignition or explosion.
• the transport gas in the line (s) 3, 4 can be air or a gas with low oxygen content or without oxygen, such as fumes, so as to avoid the presence of oxygen in the hopper 9. This avoids possible risks of combustion or explosion if unfortunately regeneration gases were to enter said hopper 9.
• Said hopper 9 is preferably provided, but not necessarily.
• the used absorbent leaves the hopper 9 via a line 10 which comprises, for example, a rotary lock or a valve 11, and it is sent by pneumatic transport to a filter reactor 12.
• the gas used to transport the absorbent spent is preferably made up of regeneration gas, brought by a line 13 which opens into line 11.
• This so-called regeneration gas which is at a temperature between 700 and 1500 ° C, and preferably between 900 and 1100 ° C, is preferably obtained by partial combustion of H2S in a burner 14 placed on line 13.
• the sensible heat of the gas in line 13 is sufficient to heat the spent absorbent before its introduction into the filter reactor 12.
• the used absorbent can be mixed with the regeneration gas at the inlet of the filter reactor.
• the filter reactor comprises a first mixing zone supplied by two circuits separate from spent absorbent and regeneration gas; this first mixing zone being followed by the filter elements proper.
• the filter reactor 12 Most of the spent absorbent, entrained by the transport gas, adheres to the filter elements of the filter reactor 12 where it forms a cake.
• This cake can be regularly unclogged using a device 15 which momentarily creates a back pressure downstream of the filter elements by a sudden injection of a certain amount of regeneration gas or a neutral gas such as nitrogen.
• the filter reactor consists of several compartments, each compartment comprising one or more filter elements. With this configuration, it is possible to unclog the compartments one after the other and not simultaneously. The jolts are thus minimized; which improves the stability of the unit and facilitates its operation.
• the unclogging causes the cake to fall into the lower part of the filter reactor 12 where an accumulation is formed.
• Fresh regeneration gas can optionally be introduced into the lower part of the filter reactor 12 by a specific line 16. A pseudo fluidized bed is thus formed in which the regeneration reaction continues.
• the regeneration gas leaves the filter reactor 12 via a line 17. Part of the sensible heat of this gas is recovered in a heat exchanger 18 disposed on the line 17. This heat can for example be used to generate steam d water used on site.
• the heat exchanger 18 can advantageously be equipped with a means for recovering liquid sulfur, liquid sulfur which is formed during the partial combustion step of the regeneration gas and during the regeneration of the absorbent. Sulfur liquid is evacuated by a line not shown in the figure, and will join for example the circuit of a Claus unit.
• the regeneration gas can be taken up at the outlet of the exchanger 18 by a line 19 to be sent to a Claus unit. Given its composition, the regeneration gas can be introduced directly at the first sulfur condenser of the Claus unit (not shown).
• the present invention makes it possible to use as regeneration gas hydrogen sulphide which is always present in a significant amount in refineries, and normally treated in a Claus unit to be converted into sulfur.
• the present invention therefore makes it possible to increase the processing capacity of the Claus unit by using part of the hydrogen sulphide intended for the Claus unit for the regeneration of the used absorbent.
• the regenerated absorbent is discharged in the lower part of the filter reactor 12, by a line 20 which comprises for example a rotary lock and an ejector.
• a pneumatic transport gas via a line 21, opens into line 20.
• the regenerated absorbent can for example be transported to the desulphurization zone of a boiler or else to temporary storage.
• a beneficial effect linked to the invention is obtained thanks to the partial combustion of the hydrogen sulphide contained in the regeneration gas: the formation of hydrogen by dissociation during the combustion of I ⁇ 2S makes it possible to enrich the regeneration gas with H2 which increases the conversion rate of the regeneration reaction.
• the recycling of the regeneration gas is no longer necessary, which makes it possible to remove certain constituents such as a draft fan.
• the gaseous effluent from the regeneration of the absorbent can be sent to a Claus unit upstream or downstream of the first condenser.
• a used absorbent flow rate of 5094 kg / h is extracted from the deduster 1 by line 4.
• This absorbent has a mass sulphation rate of 58% and a temperature of 180 ° C. It is sent by pneumatic transport to the hopper 9 using 5100 kg / h of desulphurized fumes as transport fluid.
• a H2S flow of 3510 kg / h is introduced into the burner 14 where it is partially oxidized by an air flow of 4000 kg / h.
• the fumes obtained are discharged through line 13. They are at a temperature of 1128 ° C. and contain 15% by weight of H2S, 0.4% by weight of H2, 1.2% by weight of SO2 and 29% by weight of sulfur. .
• These fumes are mixed with the spent absorbent extracted from the hopper 9 via line 11 and introduced into the filter reactor 12.
• the inlet temperature into the reactor is 790 ° C.
• the regenerated absorbent is extracted from the filter reactor 12 by line 20.
• This absorbent has a flow rate of 3900 kg / h, a sulfation rate of 26% and a temperature of 680 ° C.
• the gas used for the regeneration is extracted from the filter reactor 12 by line 17. It is cooled to 350 ° C. by the exchanger 18. This gas has a flow rate of 8700 kg / h and contains 12% by weight of SO 2, 12.7% by weight of H2S and 25.4% by weight of sulfur.
• the regeneration gas and the spent absorbent must be brought to a temperature of between 600 ° C. and 1000 ° C. to allow the regeneration reaction.
• heating is performed by means of an exchanger followed by an oven.
• the heating of the regeneration gas is ensured by a partial combustion of hydrogen sulphide which makes it possible to bring the regeneration gas to a temperature above 1000 ° C.
• the spent absorbent is heated by mixing the gas and the absorbent before introduction into the regeneration unit. This heating means therefore makes it possible to remove two expensive pieces of equipment from the regeneration circuit: the exchanger and the preheating oven.

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• Chemical & Material Sciences (AREA)
• Analytical Chemistry (AREA)
• Chemical Kinetics & Catalysis (AREA)
• Organic Chemistry (AREA)
• Engineering & Computer Science (AREA)
• General Chemical & Material Sciences (AREA)
• Oil, Petroleum & Natural Gas (AREA)
• Physics & Mathematics (AREA)
• Thermal Sciences (AREA)
• Health & Medical Sciences (AREA)
• Inorganic Chemistry (AREA)
• Biomedical Technology (AREA)
• Environmental & Geological Engineering (AREA)
• Treating Waste Gases (AREA)
• Solid-Sorbent Or Filter-Aiding Compositions (AREA)

Applications Claiming Priority (3)

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• 2000
  • 2000-06-02 FR FR0007121A patent/FR2809638B1/fr not_active Expired - Fee Related
• 2001
  • 2001-05-31 EP EP01940660A patent/EP1286765A1/de not_active Withdrawn
  • 2001-05-31 KR KR1020027001405A patent/KR20020040766A/ko not_active Withdrawn
  • 2001-05-31 JP JP2001587905A patent/JP2003534897A/ja active Pending
  • 2001-05-31 AU AU74175/01A patent/AU7417501A/en not_active Abandoned
  • 2001-05-31 WO PCT/FR2001/001700 patent/WO2001091900A1/fr not_active Ceased
  • 2001-05-31 US US10/048,167 patent/US6960548B2/en not_active Expired - Fee Related
• 2004
  • 2004-09-27 US US10/949,213 patent/US7678344B2/en not_active Expired - Fee Related

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