JP3005690B2 - Method for desulfurization of gas effluent in circulating fluidized bed with renewable absorbent - Google Patents

Description

The present invention relates to a renewable gas stream comprising substantial amounts of sulfur compounds, such as sulfuric anhydride, sulfurous anhydride, hydrogen sulfide, sulfur, carbon oxysulfide, mercaptan. The present invention relates to a desulfurization method using a fluidized bed in a fluidized bed using an absorbent.

More particularly, the invention applies to a process for desulphurizing a gas stream produced during the regeneration of a catalyst in which coke has been deposited during a catalytic cracking operation of a hydrocarbon feed. These gas streams generally contain sulfur contaminants that are diluted in soot that is difficult to exploit under these conditions.

[Prior art and problems to be solved] Patent US429,089 describes the introduction of a renewable absorbent material into a catalytic cracking device, which fixes the sulfurous anhydride released during the combustion of coke deposited on a cracking catalyst. ing. In the regenerator and the reactor (riser), these absorbents flow as a fluidized bed together with the catalyst, and are decomposed in the reactor while releasing hydrogen sulfide. Some of the sulfur introduced with the feed is sent to the fractionation column and then to the Claus-type apparatus. Although this desulfurization method does not involve a large excess investment, it is advantageous in terms of cost, but also presents disadvantages. The absorbent used has special properties: chemical composition, specific surface area. These can trigger a cracking reaction with little selectivity. In addition, the amount of absorbent required must be large, which causes dilution of the catalyst, which leads to a reduction in conversion.

Since the operating conditions of the reactor (riser) are adjusted to maximize the production of the desired hydrocarbons that can be effectively utilized, and not according to the desulfurization performance,
The desulfurization rates achieved under these conditions are not as expected.

The prior art is also illustrated by patent US 4,283,380. Here, in some cases, including oxides of Group VB and VIII metals, so as not to impair the porous structure of alumina by the absorbent consisting of alumina,
At temperatures not exceeding 400 ° C., soot desulfurization is carried out in the fluidized bed in the absorption zone. After the desulfurization, the alumina flowing through the moving bed is regenerated by gravity. However, this method cannot be applied directly to the reclaimed effluent of catalytic cracking due to their temperature level, which generally corresponds to a temperature of 600-800 ° C.

Further, Patent Applications EP-A-0214910, EP-A-021,5
Prior art is indicated by 709, GB-A-2048932 and US-A-4,423,019.

In addition, the reclaimed effluent contains low concentrations of sulfur contaminants, making it more difficult to exploit them later, especially in Claus-type devices.

[Means for Solving the Problems] The method according to the present invention can solve these disadvantages and solve the problems raised, but at the same time, has a good desulfurization yield and a good regeneration rate of the absorbent. can get. The method is particularly applicable to the desulfurization of soot resulting from the regeneration of a catalytic cracking catalyst. Furthermore, this method makes it possible to effectively utilize sulfur compounds generated from the soot to be treated.

Indeed, a substantial amount of sulfur compounds, for example, a method for desulfurizing SO _2, SO ₃ and / or H gas stream containing ₂ S, in the absorption zone, at absorption conditions, in the presence of an oxygen-containing gas,
Absorption step of these compounds into the absorbent, in the regeneration zone, under regeneration conditions, in the presence of a reducing gas, in the presence of a reducing gas, a regeneration step of the sulfur compound-rich absorbent,
And a method comprising a step of recycling at least a portion of the regenerated absorbent material to at least a portion of the absorption zone.

More precisely, the absorption step comprises: a) at least one zeolite, magnesium oxide, nickel oxide, iron oxide, vanadium oxide and optionally aluminum oxide, cerium oxide, cobalt oxide, platinum oxide and / or oxide in the matrix. Introduction of particles of an absorbent material containing palladium in a suitably selected proportion into the first end of the absorption zone, wherein the absorbent material has a particle size of 5 to 5000 micrometers and a ratio of 0.1 to 500 m ² / g. B) having a surface area of 0.3 to 40 m / s,
Introducing a gas stream at the end of the absorption zone at a temperature of about 400-1000 ° C .; c) reducing the sulfur content of the gas stream in the presence of an oxygen-containing gas and introducing the metal into step a) Contact of said particles with said gas stream in a fluidized bed under absorption conditions so as to obtain a mixture of sulfate-rich particles of the above and sulfur-poor gas effluents; d) opposite the absorption zone At the separation zone at the end of
Separating at least a portion of the sulfate-rich particles from the sulfur-poor gas effluent; e) recovering a first gas effluent having a low sulfur content.

The method further comprises the step of: f) reducing at least a portion of the sulfur-rich particles in the fluidized bed to obtain a regenerated particle mixture and a sulfur-rich second effluent. Temperature 400-1 with gas
000 ° C, surface velocity of gas generated in fluidized bed 0.3-40m /
contacting in the regeneration zone at s; and g) separating at least a portion of the regenerated particles and the second effluent in a separation zone downstream of the regeneration zone; and h) recovering the second effluent. It is characterized by.

The process according to the invention shows, over the prior art, the advantage of better contact of the particles with the gas in the desulfurization and regeneration zone by using a zeolite material. Similarly, the regenerated effluent of the resulting catalyst can be treated in two steps. One of these steps was performed in a reducing medium.

In contrast to the patents US Pat. Nos. 4,240,899 and 4,175,275, the absorption zone and the regeneration zone according to the process are different, distinguishing them from the catalytic cracking reaction zone and the regeneration reaction zone of the coke-containing catalyst. This makes it possible to optimize the temperatures of the absorption zone and the regeneration zone of the absorption material.

The regenerated effluent resulting from the process according to the invention, which has become very sulfur-rich, especially sulfurous anhydride-rich, is passed through a Claus-type apparatus in which all sulfur compounds are converted to sulfur.
Alternatively, it can be effectively used by passing sulfuric acid through a production apparatus.

According to a particular embodiment, the presence of at least part of the reducing torch gas derived from the distillation of catalytic cracking effluent, by reduction of the catalyst bed of H ₂ S, can be processed regeneration effluent. The products resulting from the catalytic reduction reaction are then processed in the amine unit and then in the Claus-type unit in the usual manner.

According to a feature of the method, a more or less complete combustion reaction of the gas stream, catalyzed by the metal oxide of the absorbing material,
And step (c) necessary for desulfurization reaction with metal oxide
The amount of oxygen introduced into the at least 2% by volume of oxygen,
For example, collecting a first gas effluent containing 2 to 5% by volume of oxygen.

The main reactions carried out are as follows: a combustion reaction catalyzed by the metal oxide of the absorbent: CO + 1/2 (O ₂ + 4N ₂ ) → CO ₂ + 2N ₂ H ₂ +1/2 (O ₂ + 4N ₂ ) → H ₂ O + 2N ₂ COS + 3/2 (O ₂ + 4N ₂ ) → C ₂ O + SO ₂ + 6N ₂ H ₂ S + 3/2 (O ₂ + 4N ₂ ) → H ₂ O + SO ₂ + 6N ₂ SO ₂ +1/2 (O ₂ + 4N) _{2) → SO 3 + 2N 2} · metal oxides by desulfurization ^{_{reaction: SO 3 + MO * → SO}} 4 M ** SO 2 +1/2 (O 2 + 4N 2) + MO * → SO 4 M ** + 2N 2 MO * = metal SO ₄ M ^** = metal sulfate.

The substances which absorb the sulfur compounds of the gas stream are impregnated with magnesium oxide, nickel oxide, vanadium oxide, iron oxide and optionally platinum oxide, palladium oxide, aluminum oxide, cobalt oxide and / or Contains zeolite in a matrix containing, in particular, silica, in a proportion by weight of 5 to 25%, based on 75 to 95% of the matrix mixed therewith: zeolite + matrix 30 to 98.97% MgO 1 to 30%, preferably 10~20% CoO 0~2000ppm, preferably 0 to 100 ppm NiO 100 to 2000 ppm, preferably 500~1000ppm Fe ₂ O ₃ 100~2000ppm, preferably 100~1000ppm V ₂ O ₅ 100~2000ppm, preferably 500～1000Ppm al ₂ O ₃ 0~30%, preferably 10~30% CeO ₂ 0~10%, preferably 1 to 10% PtO 0 to 100 ppm, preferably 5 to 50 ppm PdO 0 to 100 ppm, preferably 5 to 50 ppm.

The zeolite used is used for catalytic cracking of petroleum feedstocks and contains at most 5% by weight of coke,
For example, it may be an aluminosilicate-based zeolite which may contain 1 to 3%, for example zeolite ZSM5, faujasite Y.

Advantageously, the particles of the absorbent material may have a particle size of 20 to 100 micrometers, preferably 20 to 50 micrometers. In this way, settling of the catalyst in the unit, which would cause a loss of efficiency of the absorbent, is avoided.

The surface velocity of the effluent gas generated in the fluidized bed in the absorption zone is advantageously between 8 and 30 m / s.

According to another feature of the method, the magnesium oxide used in step (c) and the sulfur compounds contained in the gas stream have a molar ratio of 1 to 20, preferably 1 to 10.

Thus, advantageously operating at a temperature of 500-800 ° C, an excellent desulfurization rate of 98% or more was obtained. In this way, the regenerated soot of the cracking catalyst can be directly desulfurized such that the temperature at the outlet of the regenerator is substantially the same.

Metals (Mg, V, Ni, Fe and possibly Al, Ce,
The process of regenerating particles of the absorbent in the form of sulfates of Co, Pt and Pd) is usually carried out in a fluidized bed regenerator with
It may be carried out in the presence of hydrogen sulfide, sulfur in vapor form or a reducing gas which is a torch gas (fuel gas), advantageously at a temperature of 500 to 800 ° C. Preferably, the torch gas is generated by distillation of the catalytic cracking effluent. Regeneration is generally performed in countercurrent with a surface velocity of the effluent gas in the fluidized bed of 0.3-1 m / s.

For example, in the case of using methane, the reaction according to the desired stoichiometry and operating conditions are as _{follows: 4MSO 4 + 3CH 4 → 4S} + 3CO 2 + 6H 2 O + 4MO 4MSO 4 + CH 4 → 4SO 2 + 2H 2 O + CO 2 + 4MO MSO 4 + CH ₄ → H ₂ S + H ₂ O + CO ₂ + MO According to another feature of the invention, the zeolite catalyst used in the production of the desulfurized material may come from the catalyst purge of a fluidized bed catalytic cracking unit. This catalyst bed already contains the elements which make up the desulfurization material according to the invention, for example the feed which is optionally treated or the nickel, cobalt, iron, vanadium, platinum provided by the catalyst. So just in this case, a supplemental absorbent,
That is, MgO or MgO and possibly Al ₂ O ₃ would have to be added thereto.

According to another feature of the method, usually the regeneration zone comprises a molar ratio of 1 to the metal sulphate generally contained in the particles.
The reducing gas is introduced at 2020, preferably 2-10.

According to another feature of the method, in a heat exchange zone operating as a fluidized bed, located upstream of the regeneration zone,
By circulating at least a part of the sulfate-rich particles, or by performing partial combustion of the reducing gas in the regeneration zone so that the temperature becomes 400 to 1000 ° C., and adjusting the temperature of the regeneration zone. Is also good.

According to another feature of the method, after step (g), at least a part of the regenerated and separated particles may be passed in a second heat exchange zone. This is the same as in the previous case, for example, which operates in a fluidized bed prior to performing the particle recirculation step in the absorption zone. The gas stream that has to be desulfurized may come from any purification unit. This may in particular result from the regeneration of the spent catalyst of catalytic cracking in at least one regeneration zone. When the cracking device includes two regeneration zones, the gas flow may come from the first regeneration zone, or the second regeneration zone, or the entire two zones. In this case, it may contain substantial amounts of oxygen introduced in excess during regeneration of the spent catalyst.

The preparation of the desulfurized material can be carried out in various ways: for example, soluble salts of magnesium, nickel, vanadium, iron and optionally platinum, palladium, aluminum, cobalt, especially nitrates, sulphates of said metals Catalyst solution (zeolite +
Matrix)), drying the resulting product in air and calcining. The salt concentration of the solution depends, of course, on the desired oxide content for the substance and the solubility of said salt in the solution. The solubility is, for example, 10 to 26 g per 100 g of water.
SO ₄ Mg, or 10 to 50 g of magnesium acetate per 100 g of water, 0.001 to 0.050 g of vanadyl sulfate per 100 g of water, water 1
There will be 0.001 to 0.050 g of ferric nitrate per 00 g and 0 to 0.001 g of platinum chloride, 0 to 0.001 g of palladium chloride, 0 to 0.050 g of nickel nitrate per 100 g of water.

The impregnation could be performed once or several times by drying the product obtained after each operation.

The drying temperature will advantageously be between 100 and 150 ° C. After drying,
The product obtained is calcined in a furnace under air at a temperature of 400-800C.

-For example, a catalyst substance (zeolite + matrix)
Suitable particle size 5-5000 micrometers, advantageously 20-10
By 0 micrometer intimate mixing with the oxide-containing powder. The powder can be obtained by any means that results in a metal oxide powder. This can be achieved, for example, by spraying an acid-treated alumina suspension at 350-550 ° C. to form a magnesium oxide gel and suspension containing nickel, vanadium, platinum, palladium, cobalt, cerium and iron salts in solution. Will be dry to get.

The particle size of the magnesium oxide used is advantageously between 5 and
It is 500 micrometers, preferably 20 to 100 micrometers.

The concentration of the salt soluble in the alumina and magnesia suspension is calculated to obtain the desired content of said oxide in the absorbent. This is advantageously between 0 and 0.001% by weight for platinum and palladium salts and between 0 and 0.00% for cobalt salts.
5% by weight, 0.0 for vanadium, nickel and iron salts
It will be between 01 and 0.05% by weight.

First and diagrammatically and schematically showing an apparatus for performing the method
The invention will be better understood from the figures. This figure shows a fluidized bed cracking device with two regenerators supplying a gas stream containing sulfur compounds to this gas stream desulfurization device.

According to this figure, the device comprises a riser (1),
This bottom is supplied with steam from line (2), hot cracking catalyst from line (3) and sulfur-containing hydrocarbon feed from line (4).

After cracking, the mixture of catalyst and effluent hydrocarbon vapor is sent to a stripper (5). This is supplied with steam from line (6). The hydrocarbon vapor with the particles removed exits the stripper via line (15),
Sent to the fractionation tower (not shown).

Line (7) from the stripper (5) sends spent catalyst containing coke and sulfur compounds to the bottom of the first regenerator (8). Here, under the first regeneration conditions known per se, partial combustion of the components deposited on the catalyst takes place in the presence of air sent from the line (9). The partially regenerated catalyst then passes through a second regenerator (12) via a conduit (10) (lift) supplied with steam via line (11). On the other hand, the effluent of the first regeneration is collected after being collected in at least one internal or external cyclone (14a) and sent at a temperature of about 700 ° C. via a conduit (17) to a device according to the invention described below. . These effluents of the first regeneration, which are particularly rich in hydrogen, hydrogen sulfide, incompletely burned hydrocarbons, and carbon monoxide, are generally at a higher pressure than the pressure in the second regenerator. These are energy recovery turbines (1
The pressure may be reduced in 6). The inlet of the turbine is connected to the cyclone (14a) by a conduit (17), and the outlet is connected to the conduit (20). The flow control valve (19a) is arranged on this.

The second regenerator (12) receives the partially regenerated catalyst particles, which are known per se by replenishment of oxygen sent via conduit (13) to the bottom of the second regenerator (12). The partially regenerated catalyst particles can be almost completely regenerated under the obtained second regenerating conditions. The catalyst particles are then recycled to the riser supply via line (3).

The effluent of the second regeneration is collected by the internal or external cyclone (14b) of the regenerator (12). They are especially rich in sulfurous anhydride, carbonic anhydride and generally contain an excess of oxygen. These effluents are at a temperature of about 800 ° C. These are the cyclones (14) of the second regenerator (12).
b) By the outlet conduit (18), the tubular desulfurization reactor (2
1), generally in the first half, preferably the first third, of the distribution bed. In contrast, the effluent of the first regenerator is preferably introduced at the bottom of the reactor above the dense phase, at substantially the same pressure as the effluent of the second regenerator, Feed to the bottom of the end. The effluent pressure control valves (19a) and (19b) are on conduits (20) and (18), respectively. The desulfurization reactor (21) is elongated tubular and preferably has a circular cross section. For example, an injection means such as a Venturi tube (not shown in the drawing) allows a substantial axial injection of the first regenerating effluent, for example by means of an injection means such as a nozzle. )) Can be substantially radially injected with the effluent of the second regeneration.

If the excess air in the second regenerator is insufficient in the desulfurization reactor to ensure complete combustion of the effluent coming from the first regenerator and sulphation of the absorbent, supplementary supplementation of air May be carried out by a conduit leading to this reactor, preferably between the two inlet levels of the effluent.

Absorbent particles, such as magnesium oxide, nickel oxide, dispersed in a silica-alumina matrix,
The zeolite ZSM5, which contains iron oxide and vanadium oxide in appropriate proportions and comes from the recirculation means described below, is also supplied to the reactor (21) by conventional introduction means arranged at the end of the conduit (29). Supplied to In some cases, via lines (44) and (44a), the regenerated particles are absorbed in the absorption zone (2
It can also be sent directly to 1).

Fresher particles coming from another source, which constitute a loss due to purging, may be introduced via line (23). These two lines preferably communicate between two inlet levels (18) and (20) of the gas effluent.

In this way, the entire absorbent particles come into contact with the gas effluent stream, as a fluidized bed in the reactor (21), co-current from bottom to top, during which the combustion and desulphurization take place over almost the entire length of the reactor. It circulates between. The fluidization rate of this bed is 0.3
~ 40m / s.

The desulfurization effluent is separated from the particles in at least one cyclone (26) whose inlet is connected to the upper end (25) of the reactor (21) and is recovered by a line (27), not shown in the drawing Collected in the boiler.

The particles exit the cyclone (26) via outlet (26b) and fall into a fluidized bed cooling enclosure (28). This enclosure has at least two fluidization compartments (30) (31) separated by a partition (32) at part of its height.

The first compartment (30) receives the hot absorbent, which may be optionally re-injected to the level at the lower end of the desulfurization reactor by a conduit (29).

A hot particle flow control valve (35) can limit the amount of these particles in the reactor. This causes an overflow of these hot particles into the compartment (31). This compartment is cooled by a conventional type of heat exchange tube bank (33) immersed in the floor. The cooled particles are then removed from the compartment (31) by a conduit (36) regulated by a flow regulating valve (34) from a regenerator (37).
To the end.

Thus, if necessary, the absorbent particles that have become rich in sulfate due to the combustion and sulfation reactions in the reactor (21) may be cooled. This is because the reaction is exothermic by passage in the compartment (31) containing the heat exchanger (33). Control valves (34) and (35) on lines (36) (29), respectively, allow the flow rate and heat exchange intensity of the particles in the various compartments to be adjusted. Line (36) ensures the transfer of particles in the form of metal sulphate towards the bottom of the regenerator (37). The regenerator operates in a fluidized bed and is of the conventional cylindrical type. A reducing gas, for example methane, is introduced via a line (38) connected to the injector (39). These injectors ensure fluidization of the particles in the regenerator (37). Since the regeneration reaction of absorption is endothermic, if the temperature in the regenerator is not sufficiently high, means (40) suitable for performing partial combustion of the reducing gas may be introduced.

Regeneration of the metal oxide sorbent is carried out using a cocurrent flow of particles and reducing gas, and the surface velocity of the effluent gas in the regenerator is 0.3-40 m / s. Once regenerated, the particles are partially separated from the regenerated effluent in an internal or external cyclone (41) located at the top of the regenerator. The concentrated effluent is partially discharged by a conduit (42), for example to a Claus-type device. The regenerated metal oxide absorbent particles are sent to another cyclone (43) via a pipe (44) by means (45) (gas lift) supplied with steam. The effluent is discharged via line (46) to the top of the cyclone and likewise to the Claus device. The separated particles are cooled in the cooling enclosure (28) and then recycled via line (29) to the bottom of the absorption tower (21).

At least periodically, the purging of the absorbent particles is carried out at various points of the device, for example by a line (47) at the bottom (22) of the tower (21) or by a line (48) at the bottom of the cyclone (43). May be implemented.

Examples The present invention can be understood by the following examples, which illustrate the method without limitation.

Example 1 Regeneration of a catalytic cracking catalyst is carried out in a catalytic cracking apparatus having two regenerators as shown in FIG. The effluents from the two regenerators have the following composition:
Has flow rate and temperature (Table I).

The absorbent has the following weight composition: Zeolite ZS
M5: 25%, silica / alumina matrix 73.05%, MgO
= 1.5%, NiO = 0.1% , V 2 O 5 = 0.15%, PtO = 4ppm, Fe 2 O
₃ = 0.2%. This particle size is 40-60 micrometers,
This specific surface area is 150 m ² / g.

The gas stream of the absorbent and the first regenerator is introduced into the lowest zone of the absorption reactor having a flow bed of 16 m high and 5 m inside diameter, while the flow of the second regenerator is Introduced to higher points.

Air for combustion and oxidation of sulfur compounds has a flow rate of 31000N
An effluent gas introduced at m ³ / h and containing about 2% oxygen at the outlet of the reactor is obtained.

The surface velocity of the effluent gas in the fluidized bed is about 10 m / s and the temperature regulated by the heat exchanger downstream of the separator is 600 ° C
It is.

The total flow rate of the absorbent in the pipes (29) and (36) is about 800T
/ h.

The purified gas leaving the separation cyclone (26) has the following composition: N ₂ = 74.4%, CO ₂ = 13.9%, H ₂ O = 9.6%, O ₂ = 2%, C
O = 10 ppm, SO ₂ = 40 ppm.

The desulfurization yield is about 95.7%. Some of the substances that have absorbed the sulfur compounds have a flow rate of 51 T / h and a regenerator (height 2 m, diameter 1.6
m) towards the bottom. In this regenerator, the fluidization of the bed is ensured by a torch gas having the following volume composition: H ₂ = 23.5%, CH ₄ = 55.7%, C ₂ H ₆ = 3.7%, CO ₂ = 0.4
%, N ₂ = 16.8%.

Torch gas is introduced at a flow rate of 150 Nm ³ / h and its surface velocity is 0.4 m / s at the level of the fluidized bed.

The molar ratio of the reducing compound contained in the gas to the metal sulfate absorbing the sulfur compound contained in the absorbent particles is about 1.11.

 The temperature of the fluidized bed is 600 ° C.

The composition of the effluent gas at the outlet of the regenerator are as follows: SO _2: 47 _{volume% H 2 O: 33% CO} 2: 14.5% N 2: 3.8% H 2 S: trace S: trace H _2: < 1% CH ₄ : <1% There is a characteristic SO ₂ enrichment of the effluent which can then be sent to the Claus-type apparatus. The regeneration rate of this substance is 99%.

Example 2 Regeneration of a catalytic cracking catalyst is performed in a catalytic cracking apparatus having a regenerator. The effluent leaving the regeneration step has the following composition, flow rate and temperature: N ₂ = 76.745% by volume, CO = 0.005%, CO ₂ = 13%, H ₂ O =
8%, SO ₂ + SO ₃ = 0.25%, O ₂ = 2%, flow rate: 150,000Nm ³ /
h, temperature 750 ° C.

The absorbent material has the following weight composition: faujasite zeolite 12%, magnesia silica matrix 8
5.67%, MgO: 1%, NiO: 0.07%, V 2 O 5 = 0.11%, Ce 2 O 3 =
1%, Fe ₂ O ₃ = 0.15%. The particle size is 60 to 100 micrometers, a specific surface area of 200m ² / g.

The gas stream leaving the absorber and cracking regenerator
Introduced in the lowest zone of the absorption reactor in a fluidized bed comparable to that of Example 1. The velocity of the effluent gas in the fluidized bed is about 10 m / s and the temperature regulated by the heat exchanger downstream of the separator is 550 ° C.

The purified gas leaving the separation cyclone (26) has the following composition: N ₂ = 77% by volume, CO = 0.01%, CO ₂ = 13%, H ₂ O = 8%,
SO ₂ + SO ₃ = 0.004%, O ₂ = 2%.

 The purification yield is 98.4%.

Some of the material that has absorbed the sulfur compounds is sent to the bottom of the regenerator at a flow rate of 50 T / h. The regenerator, the gas rich in CH _4, bed fluidization is ensured. The composition of the gas is as follows: CH ₄ = 80 _{volume%, C 2 H 6 = 2} %, N 2 = 18%.

The CH ₄ rich gas is introduced at a flow rate of 112.5 Nm ³ / h and the surface velocity at the level of the fluidized bed is 0.3 m / s.

The molar ratio of methane contained in the gas to metal sulfate that absorbs sulfur compounds contained in the absorbent particles is about
It is 0.275.

The temperature of the fluidized bed is 650 ° C. The composition of the effluent gas at the outlet of the regenerator are as follows: SO _2: 55.2 volume% H ₂ O: 27.6 volume% CO _2: 13.8 volume% N _2: 3.4 volume% H ₂ S: trace S: trace H _2: trace _{CH 4: 1% C 2 H} 6: 0.5% SO 2 effluent becomes rich may be sent towards the Claus-type device.

The regenerated absorbent material is sent to an absorption step. Material regeneration rate is 99%.

Example 3 The effluent of the regeneration of a catalytic cracking catalyst carried out in an apparatus having two regenerators, for example as described in Example 1, is treated.

These effluents, in composition, flow rate and temperature,
It is the same as that of Example 1 shown in Table 1.

The desulfurization material consists of spent catalyst used in catalytic cracking equipment. To this, magnesia-alumina powder obtained by spraying an alumina-magnesia suspension is added.

This alumina-magnesia suspension is obtained as follows:-Mixing of alumina powder with deionized water;-To carry out peptization of alumina and to produce alumina gel used as binder Addition of concentrated nitric acid; addition of magnesia suspension under strong stirring.

The solids content of the alumina gel and the magnesia suspension is calculated to obtain compounds with a weight composition of 30% MgO and 70% Al ₂ O ₃ respectively.

The colloid solution is then formed by drying by spraying with air at 500 ° C. In this way,
Spherical particles with an average size of about 50 to 60 micrometers are obtained.

The start-up of the absorption and regeneration device is carried out as follows: In the absorption and regeneration reactor, a spent catalyst having the following weight composition is introduced: Zeolite ZSM5 = 12% silica-alumina matrix = 85.8 Pt = 5 ppm NiO = 1.7% V ₂ O ₅ = 0.35% Fe ₂ O ₃ = 0.15% Then, via line (50), the regenerated catalyst was withdrawn from the catalytic cracking unit (2 T / day) and the alumina obtained by spraying was removed. Incorporate magnesia powder 0.2T / day there,
The mixing of the regenerated catalyst and the powder is performed on a rotating drum. This mixture is introduced via line (23) into the absorption part of the sulfur compounds at a rate of 2.2 T / day.

The total weight of absorbent material is maintained in the absorption reactor by withdrawing about 2.2 T / day of material via line (51).

-After 8 days of operation under the conditions of Example 1, the average weight composition of the absorbent is as follows: zeolite ZSM5 = 10.9%, silica matrix = 78,
Alumina = 6.36 MgO = 2.73%, NiO = 1.54%, V 2 O 5 = 0.32%, PtO = 4.5
_{ppm, Fe 2 O 3 = 0.136} %. The purified gas leaving the cyclone (26) has the following volume composition: N ₂ = 74.4%, CO ₂ = 13.9%, H ₂ O = 9.6%, O ₂ = 2%, C
O = 10 ppm, SO ₂ = 40 ppm. The desulfurization yield is the same as in Example 1. That is, it is 95.7%.

The regeneration conditions are the same as those in Example 1 and the composition of the effluent gas.

After 8 days of operation, the withdrawal flow rate of spent catalyst is 0.5T
/ Day. The addition flow rate of the MgO-alumina mixture is 0.05 T /
Daily, withdrawal flow at the level of the absorption reactor is 0.55 T / day.

Even under these new conditions, the SO _x purification and regeneration rates remain unchanged.

[Brief description of the drawings]

 The drawing is a flow sheet showing an embodiment of the present invention.

──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Gerard Martin Rueil-Malmaison, France (92500) Boulevard National 29 and 31 (72) Inventor Frederique Colendar Carole, France (69300) Monté・ De la sur Berry 20-20-2 (56) References JP-A-62-68527 (JP, A) JP-A-62-68528 (JP, A) JP-A-59-197724 (JP, A) JP-A-55-92141 (JP, A) JP-A-61-35821 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) B01D 53/12, 53/48, 53/81 B01J 20 / 16,20 / 34

Claims (11)

(57) [Claims] 1. A process for the desulfurization of a gas stream containing a substantial amount of sulfur compounds, for example SO ₂ , SO ₃ and / or H ₂ S, in an absorption zone, at absorption conditions, in the presence of an oxygen-containing gas. In the regeneration zone, in the regeneration zone, in the presence of a reducing gas in the form of sulfate-enriched absorbent in the presence of reducing gas, and at least partially regenerated in the regeneration zone. In a method comprising the step of recycling at least a portion of the absorbent material to the absorption zone, the method comprises the steps of: a) at least one zeolite in the matrix, magnesium oxide, nickel oxide, iron oxide, vanadium oxide, and In some cases, particles of an absorbent material containing an appropriately selected proportion of aluminum oxide, cerium oxide, cobalt oxide, platinum oxide and / or palladium oxide. , A transfer to the first end of the absorption zone, those absorbing material has a specific surface area of the particle size and 0.1~500m ² / g of 5 to 5000 micrometers; b) the surface speed of the absorption band, 0.3 40m / s
Introducing a gas stream at the end of the absorption zone at a temperature of about 400-1000 ° C .; c) reducing the sulfur content of the gas stream in the presence of an oxygen-containing gas and introducing the metal introduced into step a) Contact of said particles with said gas stream in a fluidized bed under absorption conditions so as to obtain a mixture of sulfate-rich particles of the above and sulfur-poor gas effluents; d) opposite the absorption zone At the separation zone at the end of
Separating at least a portion of the sulfate-enriched particles from the sulfur-poor gas effluent; e) recovering a first gas effluent having a low sulfur content. The method further comprises the step of: f) regenerating a mixture of regenerated particles and a sulfur-rich second effluent, at least a portion of said sulfur-rich particles in a fluidized bed and a reducing gas. With the temperature 400-1
000 ° C, surface velocity of gas generated in fluidized bed 0.3-40m /
contacting in the regeneration zone at s; and g) separating at least a portion of the regenerated particles from the second effluent in a separation zone downstream of the regeneration zone; and h) recovering the second effluent. A method characterized by becoming. 2. The method according to claim 1, wherein the amount of oxygen introduced in step (c) is such as to recover a first gas effluent containing at least 2% by volume of oxygen. 3. The absorbent material is impregnated with magnesium oxide, nickel oxide, iron oxide, vanadium oxide and optionally platinum oxide, aluminum oxide, palladium oxide, cobalt oxide and cerium oxide in the following proportions: Matrix 75-95 mixed with these
3. A process according to claim 1 or 2, wherein the matrix contains silica in a proportion of 5 to 25% by weight, based on% by weight, zeolite + matrix 30 to 98.97% by weight MgO 1 to 30% by weight NiO 100 to 2000 wt ppm Fe ₂ O ₃ 100 to 2000 wt ppm V ₂ O ₅ 100 to 2000 wt ppm Al ₂ O ₃ 0 to 30 wt% CeO ₂ 0 to 10 wt% PtO 0 to 100 wt ppm PdO 0 to 100 wt ppm CoO 0-2000 ppm by weight. 4. The process according to claim 1, wherein in step (c) the molar ratio of magnesium oxide to sulfur compound is from 1 to 20, preferably from 1 to 10. 5. The method according to claim 1, wherein in the regeneration zone, the molar ratio of the reducing gas to the sulfate of the metal contained in the particles is from 1 to 20, preferably from 2 to 10. Method. 6. In the heat exchange zone, which is operated as a fluidized bed, upstream of the regeneration zone, by means of the circulation of at least part of the sulfate-rich particles or by the partial combustion of the reducing gas in the regeneration zone. The method according to one of claims 1 to 5, wherein the temperature of the regeneration zone is adjusted so that is between 400 and 1000 ° C. 7. The temperature of the absorption zone and the regeneration zone is 500 to 8
The method according to one of claims 1 to 6, wherein the temperature is 00C. 8. The process according to claim 1, wherein the particle size is between 20 and 100 micrometers, preferably between 20 and 50 micrometers. 9. Prior to carrying out the step of recycling the particles to the absorption zone, at least part of the particles which are regenerated and separated after step (g) in the second heat exchange zone operated as a fluidized bed are passed. A method according to one of claims 1 to 8. 10. The process according to claim 1, wherein the gas stream results from the regeneration of the spent catalyst of the catalytic cracking in at least one regeneration zone. 11. The method according to claim 1, wherein the matrix is silica-alumina and / or silica-magnesia.