Classifications

• • 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
  • 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
  • B01D53/38—Removing components of undefined structure
  • B01D53/40—Acidic components
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  • 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
  • B01D53/74—General processes for purification of waste gases; Apparatus or devices specially adapted therefor
  • B01D53/81—Solid phase processes
  • B01D53/83—Solid phase processes with moving reactants
• • 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
  • B01J20/28—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof characterised by their form or physical properties
  • B01J20/28002—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof characterised by their form or physical properties characterised by their physical properties
  • B01J20/28004—Sorbent size or size distribution, e.g. particle size
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  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
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  • B01J20/00—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof
  • B01J20/28—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof characterised by their form or physical properties
  • B01J20/28014—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof characterised by their form or physical properties characterised by their form
  • B01J20/28016—Particle form
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  • 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
  • B01J20/28—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof characterised by their form or physical properties
  • B01J20/28054—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof characterised by their form or physical properties characterised by their surface properties or porosity
  • B01J20/28057—Surface area, e.g. B.E.T specific surface area
• • 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
  • B01J20/28—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof characterised by their form or physical properties
  • B01J20/28054—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof characterised by their form or physical properties characterised by their surface properties or porosity
  • B01J20/28057—Surface area, e.g. B.E.T specific surface area
  • B01J20/28059—Surface area, e.g. B.E.T specific surface area being less than 100 m2/g
• • 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
  • B01J20/28—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof characterised by their form or physical properties
  • B01J20/28054—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof characterised by their form or physical properties characterised by their surface properties or porosity
  • B01J20/28069—Pore volume, e.g. total pore volume, mesopore volume, micropore volume
• • 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
  • B01J20/28—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof characterised by their form or physical properties
  • B01J20/28054—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof characterised by their form or physical properties characterised by their surface properties or porosity
  • B01J20/28069—Pore volume, e.g. total pore volume, mesopore volume, micropore volume
  • B01J20/28071—Pore volume, e.g. total pore volume, mesopore volume, micropore volume being less than 0.5 ml/g
• • 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
  • B01J20/28—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof characterised by their form or physical properties
  • B01J20/28054—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof characterised by their form or physical properties characterised by their surface properties or porosity
  • B01J20/28078—Pore diameter
  • B01J20/28085—Pore diameter being more than 50 nm, i.e. macropores
• • C—CHEMISTRY; METALLURGY
  • C01—INORGANIC CHEMISTRY
  • C01F—COMPOUNDS OF THE METALS BERYLLIUM, MAGNESIUM, ALUMINIUM, CALCIUM, STRONTIUM, BARIUM, RADIUM, THORIUM, OR OF THE RARE-EARTH METALS
  • C01F11/00—Compounds of calcium, strontium, or barium
  • C01F11/02—Oxides or hydroxides
• • C—CHEMISTRY; METALLURGY
  • C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
  • C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
  • C04B2/00—Lime, magnesia or dolomite
  • C04B2/02—Lime
  • C04B2/04—Slaking
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01D—SEPARATION
  • B01D2251/00—Reactants
  • B01D2251/40—Alkaline earth metal or magnesium compounds
  • B01D2251/404—Alkaline earth metal or magnesium compounds of calcium
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01D—SEPARATION
  • B01D2253/00—Adsorbents used in seperation treatment of gases and vapours
  • B01D2253/30—Physical properties of adsorbents
  • B01D2253/302—Dimensions
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01D—SEPARATION
  • B01D2253/00—Adsorbents used in seperation treatment of gases and vapours
  • B01D2253/30—Physical properties of adsorbents
  • B01D2253/302—Dimensions
  • B01D2253/304—Linear dimensions, e.g. particle shape, diameter
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01D—SEPARATION
  • B01D2257/00—Components to be removed
  • B01D2257/20—Halogens or halogen compounds
  • B01D2257/204—Inorganic halogen compounds
  • B01D2257/2045—Hydrochloric acid
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01D—SEPARATION
  • B01D2257/00—Components to be removed
  • B01D2257/20—Halogens or halogen compounds
  • B01D2257/204—Inorganic halogen compounds
  • B01D2257/2047—Hydrofluoric acid
• • 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
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01D—SEPARATION
  • B01D2257/00—Components to be removed
  • B01D2257/40—Nitrogen compounds
  • B01D2257/404—Nitrogen oxides other than dinitrogen oxide
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01D—SEPARATION
  • B01D2258/00—Sources of waste gases
  • B01D2258/02—Other waste gases
  • B01D2258/0283—Flue gases
• • C—CHEMISTRY; METALLURGY
  • C01—INORGANIC CHEMISTRY
  • C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
  • C01P2004/00—Particle morphology
  • C01P2004/51—Particles with a specific particle size distribution
  • C01P2004/53—Particles with a specific particle size distribution bimodal size distribution
• • C—CHEMISTRY; METALLURGY
  • C01—INORGANIC CHEMISTRY
  • C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
  • C01P2004/00—Particle morphology
  • C01P2004/60—Particles characterised by their size
  • C01P2004/61—Micrometer sized, i.e. from 1-100 micrometer
• • C—CHEMISTRY; METALLURGY
  • C01—INORGANIC CHEMISTRY
  • C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
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  • C01P2006/12—Surface area
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  • C01—INORGANIC CHEMISTRY
  • C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
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  • C01P2006/14—Pore volume
• • C—CHEMISTRY; METALLURGY
  • C01—INORGANIC CHEMISTRY
  • C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
  • C01P2006/00—Physical properties of inorganic compounds
  • C01P2006/16—Pore diameter

Definitions

• the present invention relates to a pulverulent slaked lime composition having a BET specific surface area obtained by nitrogen adsorption, greater than or equal to 25 m 2 / g and a total pore volume BJH, consisting of pores with a diameter of less than 1000 ⁇ , greater than or equal to 0.15 cmVg.
• Calcium oxide, CaO is often referred to as “quicklime”, while calcium hydroxide, Ca (OH) 2 , is referred to as “hydrated lime” or “slaked lime”, both compounds being informally named “lime”.
• lime is an industrial product respectively based on oxide or calcium hydroxide.
• quicklime is meant a mineral solid whose chemical composition is mainly calcium oxide, CaO.
• Quicklime is generally obtained by calcination of limestone (mainly CaCO 3 ).
• the quicklime may also contain impurities such as magnesium oxide, MgO, sulfur oxide, SO 3 , silica, SiO 2 , or even alumina, Af 2 O 3 , whose sum is at a rate of a few% by weight.
• the impurities are expressed here in their oxide form, but of course they may appear in different phases.
• Quicklime usually also contains some% by weight of residual limestone, called incinerated residues.
• the suitable quicklime according to the present invention may comprise MgO, expressed in the form of MgO, in an amount ranging from 0.5 to 10% by weight, preferably less than or equal to 5% by weight, plus preferably less than or equal to 3% by weight, most preferably less than or equal to 1% by weight relative to the total weight of quicklime.
• quicklime is used in the presence of water.
• Calcium oxide in quicklime reacts rapidly with water to form calcium dihydroxide Ca (OH) 2 , in the form of slaked lime or hydrated lime, in a reaction called hydration or quenching reaction. which is very exothermic.
• the calcium dihydroxide will be simply called calcium hydroxide.
• the slaked lime can therefore contain the same impurities as those of the quicklime from which it is produced.
• the slaked lime may also comprise Mg (OH) 2 in an amount ranging from 0.5 to 10% by weight, preferably less than or equal to 5% by weight, more preferably less than or equal to 3% by weight, most preferably less than or equal to 1% by weight relative to the total weight of the slaked lime.
• the slaked lime may also include calcium oxide, which may not have been fully hydrated during the quenching step, or calcium carbonate CaCO 3 .
• the calcium carbonate can come from the initial limestone (incuit) from which the slaked lime is obtained (via calcium oxide), or from a partial carbonation reaction of the slaked lime by contact with a atmosphere containing CO 2 .
• the amount of calcium oxide in the slaked lime according to the present invention is generally less than or equal to 3% by weight, preferably less than or equal to 2% by weight and more preferably less than or equal to 1% by weight relative to the total weight of the slaked lime.
• the amount of CO 2 in the slaked lime (mainly in the form of CaCO 3 ) according to the present invention is less than or equal to 5% by weight, preferably less than or equal to 3% by weight, more preferably less than or equal to 2 % by weight, based on the total weight of the slaked lime according to the present invention.
• the quenching reaction is generally carried out in a hydrator, in which quicklime is brought upstream of the direction of quenching, i.e. the direction in which the lime is transported along and in the water. hydrator.
• the slaked lime is removed downstream of the direction of extinction.
• Transport means such as a horizontal shaft equipped with mixing blades for example, allow the transport of lime in the direction of extinction in the hydrator, from the supply of quicklime to the withdrawal of the slaked lime.
• the means of transport also allow a homogeneous mixture of lime undergoing hydration and thus improve the contact between water and lime in the hydrator and avoid the formation of hot spots.
• reactivity to water of quicklime is generally characterized and measured by the procedure indicated in the European standard EN459-2 and is often quantified by the value t 60 , which is the time required to reach a temperature of 60 ° C for a volume of water of 600 cm 3 initially at 20 ° C, with the addition of 150 g of quicklime.
• the slaked lime compositions are commonly obtained industrially by different processes depending on the amount of water used relative to the lime.
• a first production process called "dry extinction mode”
• water is added to the hydrator in a quantity limited to that which is necessary to completely hydrate the quicklime, taking into account that part will evaporate during the quenching reaction, due to the exothermic nature of this reaction.
• the resultant slaked lime product is a standard slaked lime powder composition having a BET specific surface area generally between 12 and 20 m 2 / g and generally comprising less than 2% by weight. or even less than 1.5% by weight of moisture (free water).
• Standard slaked lime generally has many applications in a large number of industrial applications such as water treatment, sludge conditioning, flue gas treatment, agriculture, construction, etc.
• the properties of slaked lime are particularly critical for good performance.
• lime is used as a sorbent for a number of gaseous pollutants such as HCl, HF, SO x , NO x .
• gaseous pollutants such as HCl, HF, SO x , NO x .
• the capture of these pollutants can be carried out under dry conditions and is therefore called "dry sorbent injection”.
• This method involves injecting powdery sorbents, such as powdered lime, directly into the flue gas stream or by a filter comprising a fixed bed of solid particles.
• the documents US5492685 and WO9209528 describe slaked lime having a specific surface area, obtained by slaking lime with an alcohol or in the presence of particular additives, such as (di-, tri- or poly-) ethylene glycol or (di-, tri- or poly-) ethanolamine.
• Another method of producing slaked lime having a high specific surface is to extinguish quicklime with an excess of water so as to obtain, at the exit of the hydrator, a wet slaked lime composition having a moisture content residual between 15 and 35% by weight.
• the wet slaked lime composition is then further dried in a drying device to reduce the moisture content and form a dried dry powdery lime composition.
• This process is generally called "semi-wet process” and is described in particular in WO97 / 14650 and US2894820.
• the resulting powdered lime slurry composition consists essentially of dry calcium hydroxide particles having a residual moisture content of less than 2% by weight of the total composition. a high specific surface area (greater than 30 m 2 / g) with a high pore volume (total pore volume by nitrogen desorption of at least 0.1 cm 3 / g for pores with a diameter less than 1000 Angstroms) .
• This lime composition further has an Alpine fluidity of between 40 and 50% and is described as having excellent performance for the treatment of flue gases in installations comprising a bag filter.
• the composition of powdered lime is handled and transported, in particular by screws or by air in pipes where the particles are distributed in the gas phase. Subsequently, the pulverulent slaked lime composition is generally stored in the compressed state, for example in silos.
• the fouling phenomenon is a recurring problem of slaked lime compositions during the production process, storage and subsequent use as a sorbent, particularly with a slaked lime composition having a small particle size.
• fouling phenomenon is understood to mean a phenomenon of fouling and adhesion during the process of production, but also during the storage, transport or subsequent use of the composition of powdered lime.
• Fouling phenomena are responsible for additional maintenance.
• the powdered lime compositions tend to adhere to the walls of the container and are then difficult to remove from these walls, thus leading to the loss of a significant amount of product.
• the application of the pulverulent slaked lime composition is compromised due to blockages that are difficult to eliminate.
• powdered lime compositions comprising smaller particles have a greater effectiveness of the treatment. More specifically, the treatment of the combustion gases is improved because of a better dispersion of the powder composition in the gas phase (flue gas) and a faster contact between the pollutants and the lime particles of the composition. In addition, the smaller particles have a larger external contact surface, thereby increasing the proportion of hydrated lime that will actually come into contact with the pollutants to be captured.
• the fluidity of a powder generally decreases as the size of the particles making up this powder decreases. Indeed, the smaller particles are known to cause the decrease in the fluidity of the powder because of the important interactions between the particles that generate the cohesion of the powder.
• This is illustrated in particular in Geldart et al. which teaches us that the flow properties of a powder measured with different flow behavior meters indicate a more difficult flow behavior when the particle size is reduced. Indeed, this paper demonstrates that the Warren Spring Bradford Cohesion Tester (WSBCT), the Johanson Cohesive Indicator, and the Paid Resting Angle and Jenike Cohesion all show an increase in their value with a particle size. (Geldart Geldart, D., Abdullah, CE, Verlinden, A. Characterization of Dry Powders, Powder Technol.2009, 190 (1-2), 70-74). As a result, so far, the skilled person has has always been forced to compromise between improved sorption properties and sufficient fluidity of its powdery sorbent.
• the pulverulent slaked lime composition according to the present invention makes it possible to provide a solution to this need by using a pulverulent powdered lime composition, as mentioned at the beginning, characterized in that the composition also has an Alpine fluidity of greater than 50%, particular greater than or equal to 51%, preferably greater than or equal to 52%, advantageously greater than or equal to 54%, in particular greater than or equal to 55%, said aforementioned composition comprising a first fraction of particles having a size smaller than 332 microns and a second fraction of particles having a size greater than 32 microns, the second fraction being less than 10 percent by weight, relative to the total weight of the composition.
• second fraction of particles larger than 32 ⁇ m is also expressed by R 32 in the remainder of the specification for the fraction retained at 332 ⁇ m.
• fluidity sometimes referred to as flowability, is meant in the present invention, the ability of a powder to flow freely, evenly and uniformly as individual particles.
• the fluidity of the pulverulent slaked lime composition according to the present invention is measured on an Alpine air-jet screening device.
• This Alpine fluidity characterizes the static fluidity of a powder and is determined by the speed of passage of particles having a diameter of less than 90 ⁇ m through a sieve of 90 ⁇ m (170 mesh) by the action of a suction.
• the Alpine fluidity expressed in% corresponds to the ratio between the weight of the fraction less than 90 ⁇ which has passed through the sieve in 15 seconds (with a depression of 100 mm of liquid of density 0,88) and the total weight of the fraction less than 90 ⁇ which passed through the sieve after another 2 minutes (with a depression of 150 mm of 0.88 density liquid).
• the behavior of a powder in a storage silo can be simulated with another method using a powder rheometer, such as a Brookfield powder flow tester (PFT) according to the A5TM D6128 standard.
• a powder sample introduced into the equipment is subject to increasing compaction over time.
• a specific torque is applied to the powder until failure (unconfined failure stress).
• the response of the powder to the applied stress is recorded by a computer, which evaluates the static cohesion of the test sample. The results are expressed as a curve that is compared to ASTM references.
• the powdered lime composition according to the invention is also characterized by a dynamic fluidity that can be measured by a Granudrum apparatus.
• a certain amount of the powder material is placed in a drum having transparent windows, which is rotated and accelerated in increments of 0 to 20 rpm, and then decelerated in stages.
• the shape of the rotating powder pile (air / powder interface) inside the drum is analyzed by an algorithm.
• a dynamic flow angle and a dynamic cohesion index are determined for each rotational speed.
• the fluidity of a powder is, among other things, governed by the particle size of the powder (see the article “Flow properties of powders and bulks solids", Dietmar Schulze http://dietmar-schulze.de/grdlel.pdf ).
• the fluidity of a powder generally decreases when the size (for example the diameter) of the particles constituting the powder decreases.
• the particle size of the powdered lime composition depends on various parameters.
• the first parameter influencing the particle size is the particle size of the quicklime that is used to form the slaked lime.
• the speed of the hydration reaction and the temperature inside the hydrator are also factors essential elements that govern the hydration reaction and consequently the size of the particles composing the final composition of powdered lime.
• Achieving a well-controlled particle size in a highly porous powdery lime composition is therefore complicated because it depends on several parameters difficult to control, especially during the quenching process to form the composition of powdered lime.
• the fluidity of the pulverulent dry lime composition depends on multiple parameters, some of which are difficult to control.
• the fluidity of the powder is an essential parameter characterizing a powder composition since a powder which is not fluid can cause a fouling phenomenon during the production process and during the storage of the powder, but also during subsequent use of this powder.
• the slaked lime can be treated in drying and grinding apparatus which can influence the size distribution, but also the shape of the particles of the pulverulent slaked lime and consequently influence the fluidity of the powder.
• the internal structure of the powdered quicklime can also be modified, and thus, the drying step can also change the porosity characteristics of the powder.
• the powdered hydrated lime composition of the present invention retains excellent because of a high porosity sorption properties, namely, a BET specific surface area obtained by nitrogen adsorption of greater than or equal to 25 m z / g and a volume porous total BJH greater than or equal to 0.15 cm 3 / g.
• the sorption properties of the pulverulent slaked lime composition according to the present invention are further improved by the particle size distribution of the composition characterized by an R 32 of less than 10% by weight based on the total weight of the composition.
• the efficiency of the treatment in particular the treatment of combustion gases, is improved by a better dispersion of the powdered lime composition in the gas phase (flue gas) and a contact faster between the pollutants and the lime particles of the composition according to the present invention.
• smaller particles have a larger external contact area, increasing the proportion of hydrated lime that will actually come into contact with the pollutants to be captured.
• a highly porous powdery lime composition composed of particles having a size of less than 32 ⁇ , with an f1 ⁇ 2 of less than 10% by weight relative to the total weight of the composition, can exhibit improved fluidity.
• the pulverulent slaked lime composition according to the present invention in addition to its very good sorption properties, has a high fluidity, which means that the powder is easier to handle, transport, store and therefore the fouling or blocking phenomena are considerably reduced during the production process or subsequent use, thus reducing the costs caused by maintenance problems of the production facility or during its subsequent use.
• Another advantage of the powder according to the present invention is the reduction of product loss caused by the fact that the powder can adhere to the inner walls in the production process, during storage, during transport and in subsequent use. .
• Increasing the fluidity of the powder according to the present invention makes it possible to avoid or at least reduce these adhesion phenomena.
• mi is the initial mass of 50 g powder distributed on a sieve of 90 ⁇ ;
• the pulverulent slaked lime composition according to the present invention comprises particles having a BET specific surface area obtained by nitrogen adsorption greater than or equal to 30 m 2 / g, preferably greater than or equal to 32 m z / g, advantageously greater than or equal to 35 m 2 / g.
• the pulverulent slaked lime composition has a BET specific surface area obtained by nitrogen adsorption less than or equal to 50 m 2 / g, in particular less than or equal to 48 m 2 / g. .
• BET specific surface area is meant according to the present invention, the specific surface area measured by nitrogen adsorption manometry at 77 K after vacuum degassing at a temperature of between 150 and 250 ° C., especially at 190 ° C. C for at least 2 hours and calculated according to the multipoint BET method described in ISO 9277: 2010E.
• the powdery lime composition according to the present invention has a total pore volume BJH consisting of pores having a diameter less than 1000 ⁇ , obtained by nitrogen desorption, greater than or equal to 0, 17 cm 3 / g, in particular greater than or equal to 0.18 cm 3 / g, preferably greater than or equal to 0.19 cm 3 / g, in particular greater than or equal to 0.20 cm 3 / g, so advantageous greater than or equal to 0.21 cm 3 / g.
• the pulverulent slaked lime composition of the invention has a total pore volume BJH consisting of pores having a diameter less than 1000 ⁇ obtained by nitrogen desorption, less than or equal to 0.30 cm 3 / g, in especially less than 0.28 cm 3 / g.
• the pulverulent slaked lime composition according to the present invention has a pore volume BJH consisting of pores having a diameter ranging from 100 to 300 ⁇ , obtained by nitrogen desorption, greater than or equal to 0.07 cm. 3 / g, preferably greater than or equal to 0.10 cm 3 / g, advantageously greater than or equal to 0.11 cm 3 / g, in particular greater than or equal to 0.12 cm 3 / g and typically less than 0.15 cm 3 / g, in particular less than 0.14 cm 3 / g.
• the pulverulent slaked lime composition according to the present invention has a pore volume BJH consisting of pores having a diameter ranging from 100 to 400 ⁇ , obtained by nitrogen desorption, greater than or equal to 0.09 cm 3 / g preferably greater than or equal to 0.12 cm 3 / g, advantageously greater than or equal to 0.13 cm 3 / g, in particular greater than or equal to 0.14 cm 3 / g and typically less than 0.17 cm 3 / g, in particular less than 0.16 cm 3 / g.
• porous volume BJH is meant the pore volume as measured by manometry with nitrogen adsorption at 77 K after degassing under vacuum at a temperature between 150 and 250 ° C, especially at 190 ". C for at least 2 hours and calculated according to the BJH method, using the desorption curve, with the assumption of a cylindrical pore geometry.
• total pore volume the pore volume BJH consisting of pores with a diameter less than or equal to 1000 ⁇ .
• powdered hydrated lime composition of the present invention further has a bottom 50 of particle size not more than 8 microns, preferably less than or equal to 6 microns, advantageously less than or equal to 4 pm.
• the notation dx represents a diameter expressed in ⁇ m, measured by laser granulometry in methanol after sonication, with respect to which X% by volume of the particles measured have a smaller or equal size.
• the pulverulent slaked lime composition according to the present invention has a non-solid residual phase content.
• said non-solid residual phase comprises water and / or residual additives (inorganic and / or organic), free or bound to the lime compound.
• non-solid residual phase content of the slaked lime composition is meant the proportion of the non-solid residual phase of the slaked lime composition (i.e. water, such as the free water content, and / or the residual additive content from the process for producing said slaked lime composition, that is to say from additives added before, during or after extinction quick lime) determined by a fire loss test.
• the proportion of the non-solid residual phase of the slaked lime composition i.e. water, such as the free water content, and / or the residual additive content from the process for producing said slaked lime composition, that is to say from additives added before, during or after extinction quick lime
• the loss on ignition test consists in heating, at atmospheric pressure, about 20 g of the pulverulent slaked lime composition at a predetermined temperature, namely 110 ° C. or 180 ° C., and measuring the weight over time of the composition. powder by means of a thermal balance until the weight of the powder does not vary by more than 2 mg for at least 20 seconds. During the heating of the powder, all the components, in particular the non-solid components, having an evaporation temperature lower than that applied during the test, are removed from the powder and their content corresponds, therefore, to the measured weight loss. during the test.
• the non-solid residual phase contains all the non-solid components, in particular the liquid components, together having an evaporating temperature lower than that applied, which will then be removed from the slaked lime composition during the heating process at the same time. predetermined temperature.
• The% by weight of the non-solid residual phase and the remaining solid, named dry extract are both calculated on the weight of the product before the fire test and after the fire test and are both expressed in relation to the weight of the product. product before the fire test.
• the result of loss on ignition can therefore vary according to the temperature used during the test. For example, it can be higher at 180 X than at 110 ° C if additives are used during or after the extinguishing process, and if these additives or their derived phases have a flash point greater than 110 ° C and less than 180 ° C, or form with free water an azeotropic substance or an aqueous mixture which evaporates between these temperatures.
• the non-solid residual phase content of the pulverulent slaked lime composition according to the present invention can be measured by a fire loss test at 180 ° C.
• the result of loss on ignition is greater than or equal to 0.3% by weight, preferably greater than or equal to 0.5% by weight and less than or equal to 5% by weight, preferably less than or equal to to 4.5% by weight, in particular less than or equal to 4% by weight and represents the amount of water and / or substances contained therein having an evaporation point of less than or equal to 180 ° C.
• the non-solid residual phase content of the pulverulent slaked lime composition according to the present invention may further be measured by a fire loss test at 110 ° C.
• the loss on ignition value is less than or equal to 3.5% by weight, preferably less than or equal to 3% by weight, advantageously less than or equal to 2.5% by weight, in particular less than or equal to 2% by weight, in particular less than or equal to 1.5% by weight and greater than 0% by weight, preferably greater than or equal to 0.2% by weight, advantageously greater than or equal to 0, 3% by weight, in particular greater than or equal to 0.5% by weight and mainly represents the amount of water and / or volatile substances contained therein having a point of evaporation of less than or equal to 110 ° C, in especially water.
• the powdery lime composition according to the invention also has an alkaline phase characterized by an alkali metal content greater than or equal to 0.2% by weight and less than or equal to 3.5% by weight relative to the total weight of the pulverulent dry lime composition.
• the alkaline phase may be in ionic form or in bound form.
• Different types of salts may be added before, during and / or after the quenching process, in particular an alkali metal compound selected from the group consisting of hydroxides, carbonates, hydrogenocarbonates, nitrates, phosphates, persulfates and alkali metal monocarboxylates, such as alkali metal acetates or formates and mixtures thereof, in particular those of sodium, potassium and / or lithium.
• the powdered lime powder composition according to the present invention further comprises inorganic solid additives and / or residual organic solid additives.
• the residual organic solid additives may come from organic additives added before, during and / or after the quenching process and selected from the group of (mono-) or (poly) ethylene glycol and (mono) or (poly) ethanolamine, especially triethylene glycol, triethanolamine, and calcium stearate and mixtures thereof.
• the particles of the powdered lime composition of the present invention consist mainly of hydrated lime, also known as slaked lime, resulting from the treatment of quicklime with water to convert the oxides to hydroxides.
• the hydrated lime of the present invention may be hydrated lime rich in calcium or dolomitic.
• the powdered lime powder composition of the present invention may contain the same impurities as the quicklime from which it is produced, such as magnesium oxide, MgO, sulfur oxide, SO 3 , silica, SiO 2 , or alumina, Al 2 O 3 , the sum of which is at a level of a few% by weight.
• the impurities are expressed here in their oxide form, but of course they may appear in different phases.
• the slaked lime according to the present invention may comprise magnesium in the form of MgO and / or Mg (OH) 2 , in an amount ranging from 0.5 to 10% by weight, preferably less than or equal to at 5%, more preferably less than or equal to 3% by weight, most preferably less than or equal to 1% by weight, expressed as oxide, relative to the total weight of the slaked lime composition.
• the slaked lime may also include calcium oxide, which may not have been fully hydrated during the quenching step, or calcium carbonate CaCO 3 .
• the calcium carbonate can come from the initial limestone (incuit) from which the slaked lime is obtained (via calcium oxide), or from a partial carbonation reaction of the slaked lime by contact with a atmosphere containing CO 2 .
• the amount of calcium oxide in the slaked lime according to the present invention is generally less than or equal to 3% by weight, preferably less than or equal to 2% by weight and more preferably less than or equal to 1% by weight relative to the total weight of the slaked lime.
• the amount of CO 2 in the slaked lime (mainly in the form of CaCO 3 ) according to the present invention is generally less than or equal to 5% by weight, preferably less than or equal to 3% by weight, more preferably less than or equal to 2% by weight, based on the total weight of the slaked lime according to the present invention.
• the quantity of lime available in the powdered lime composition according to the present invention is greater than or equal to 85% by weight, preferably greater than or equal to 87% by weight, preferably greater than or equal to 90% by weight, advantageously greater than or equal to 92% by weight, and even greater than or equal to 95% by weight relative to the solids content of the slaked lime composition after LOI at 180 ° C.
• the remaining% by weight of the slaked lime composition consists mainly of calcareous compounds and residues from the non-solid residual phase.
• quantity of lime available is meant in the present invention, the amount of calcium hydroxide and / or calcium oxide present in the pulverulent slaked lime composition, measured by a method described in standard EN - 459-2 2010. More specifically, in the present invention, the available lime content present in the composition of powdered slaked lime is determined by placing 0.5 g of the composition of powdered quicklime in a solution of sugar (15 g sugar in 150 cm 3 of demineralized water). The sugar solution will dissolve the available lime (i.e., calcium oxide and / or calcium hydroxide) contained in the sample.
• the resulting mixture is stirred for at least 10 to 15 minutes to ensure complete dissolution, and then titrated with a solution of hydrochloric acid (0.5 N HCl), phenolphthalein being used as an indicator.
• the Ca concentration measured by this titration is then expressed as Ca (OH) 2 .
• the invention also relates to an industrial sorbent composition comprising at least said powdered lime powder composition according to the invention.
• an industrial sorbent composition comprising at least said powdered lime powder composition according to the invention.
• Other embodiments of the industrial sorbent composition according to the invention are mentioned in the appended claims.
• the invention also relates to the use of the pulverulent dry lime composition according to the present invention for purifying combustion gases.
• the pulverulent slaked lime composition according to the present invention is used in a dry injection of sorbent.
• the pulverulent slaked lime composition according to the present invention is used for the capture of acid pollutants from the combustion gases, such as HCl, HF, SO x , NO x , etc.
• the pulverulent slaked lime composition according to the present invention is used in an industrial sorbent composition, for example in combination with at least one other generally known sorbent for the treatment of combustion gases, such as a sorbent selected from the list of organic compounds, in particular activated charcoal, lignite coke and mixtures thereof, and inorganic compounds, in particular inorganic compounds known to capture dioxins, furans and / or heavy metals, such as halloysite, sepiolite, bentonite or any sorbent described in application DE4034417.
• a sorbent selected from the list of organic compounds, in particular activated charcoal, lignite coke and mixtures thereof
• inorganic compounds in particular inorganic compounds known to capture dioxins, furans and / or heavy metals, such as halloysite, sepiolite, bentonite or any sorbent described in application DE4034417.
• the pulverulent slaked lime composition according to the present invention may especially be produced, but not limited to, by a method comprising the steps of: introducing quicklime into a feed zone of a hydrator; introduce water into the hydrator's feeding zone; extinguishing said quicklime in an extinguishing zone of the hydrator by means of a quantity of water which is sufficient to obtain a slaked lime having a non-solid residual phase content of between 15% and 55% by weight, of preferably between 15 and 35% by weight; drying and grinding said slaked lime to form the pulverulent slaked lime composition.
• This process is characterized in that said drying and milling steps are carried out simultaneously and are a single step of fluidifying the slaked lime to form said pulverulent slaked lime composition having an Alpine fluidity greater than 50%, the Alpine FA fluidity being defined by the equation
• m- is the initial mass of 50 g powder distributed on a sieve of 90 ⁇ ;
• drying and grinding steps being carried out in a mill-dryer selected from the group consisting of a pin mill-dryer, a cage-dryer, an instant dye-deagglomerator and a combination thereof until the powdered lime composition comprises a first fraction of particles having a size of less than 332 ⁇ m and a second fraction of particles having a size greater than 332 ⁇ m, the second fraction being less than 10% by weight, relative to the total weight of the composition.
• instantaneous deagglomerator an instantaneous drying device in which there is a rotor or rotating blades at the bottom of the drying chamber which fluidifies the product and creates turbulence in the hot air flow. which penetrates tangentially the drying chamber.
• wet (agglomerated) slaked lime is rapidly dispersed and disintegrated into fine dry particles.
• the resulting fine particles leave the drying chamber from the top while the larger particles remain in the chamber for further drying and disaggregation.
• Examples of instant drier-deagglomerator include the Anhydro Spin Flash Dryer * dryer marketed by SPX FLOW, the Drymeister * instant dryer marketed by Hosokawa Micron Group or the Swirl fluidizer TM dryer marketed by GEA Group.
• the drying-grinding steps are carried out until the pulverulent slaked lime composition has an average particle size d 50 of less than or equal to 8 ⁇ , advantageously less than or equal to 6 ⁇ m, in particular lower than or equal to 4 ⁇ .
• the drying-grinding steps are carried out until the powdered slaked lime composition has a non-solid residual phase content, measured by a fire loss test at 180 ° C, less than or equal to 5%. % by weight, preferably less than or equal to 4.5% by weight, in particular less than or equal to 4% by weight, and greater than or equal to 0.3%, preferably greater than or equal to 0.5% by weight, relative to the total weight of the pulverulent slaked lime composition.
• a highly porous and fine porous powdery lime composition according to the present invention is produced industrially by mixing water and quicklime (2.7 t / h of quicklime) in a hydrator, in such quantities that the product comes out of the hydrator with a non-solid residual phase content, measured by a fire loss test (LOI) at 180 ° C, of between 22 and 24% by weight. 0.2% diethylene glycol (expressed as a% of the weight of quicklime) is added to the extinguishing water before hydration.
• LOI fire loss test
• the wet slaked lime that leaves the hydrator is then transported to a pin mill in which hot air is injected to instantaneously dry the wet slaked lime and produce the highly porous pulverulent slaked lime composition prior to store it in a storage area.
• the resulting powdery lime composition has an Alpine fluidity of

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• 2017
  • 2017-06-23 EP EP17732132.0A patent/EP3475228A1/de not_active Withdrawn
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