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
  • B01D53/60—Simultaneously removing sulfur oxides and nitrogen oxides
• • 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
  • B01D53/343—Heat recovery
• • 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
  • B01D53/346—Controlling the process
• • 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
  • B01D53/34—Chemical or biological purification of waste gases
  • B01D53/74—General processes for purification of waste gases; Apparatus or devices specially adapted therefor
  • B01D53/86—Catalytic processes
  • B01D53/8621—Removing nitrogen compounds
  • B01D53/8625—Nitrogen oxides
  • B01D53/8631—Processes characterised by a specific device
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01D—SEPARATION
  • B01D2251/00—Reactants
  • B01D2251/20—Reductants
  • B01D2251/206—Ammonium compounds
  • B01D2251/2062—Ammonia
• • 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
  • B01D2251/00—Reactants
  • B01D2251/60—Inorganic bases or salts
  • B01D2251/602—Oxides
• • 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
  • B01D2258/0233—Other waste gases from cement factories
• • 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
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
  • Y02A—TECHNOLOGIES FOR ADAPTATION TO CLIMATE CHANGE
  • Y02A50/00—TECHNOLOGIES FOR ADAPTATION TO CLIMATE CHANGE in human health protection, e.g. against extreme weather
  • Y02A50/20—Air quality improvement or preservation, e.g. vehicle emission control or emission reduction by using catalytic converters

Definitions

• the present invention relates to a treatment method for the pollutants contained in the fumes.
• the technology presented here consists in particular of treating the sulfur oxides - by a so-called desulfurization process (DeSOx) - such as sulfur dioxide (SO 2 ), and nitrogen oxides - by a process known as denitrification. (DeNOx) -, such as nitrogen oxide (NO) and nitrogen dioxide (NO 2 ).
• the fumes to be treated come in particular from combustion sources such as combustion furnaces or coal-fired boilers, or from an oven or a calcination process for the production of cement, the production of lime, or any other method of calcination.
• Such fumes contain one or more acid pollutants such as hydrochloric acid (HCl), hydrofluoric acid (HF), sulfur oxides (SO x ) and nitrogen oxides (NO x ), which can cause damage to the environment, for example by acid rain, if these fumes are released into the atmosphere without appropriate and effective treatment.
• acid pollutants such as hydrochloric acid (HCl), hydrofluoric acid (HF), sulfur oxides (SO x ) and nitrogen oxides (NO x )
• HCl hydrochloric acid
• HF hydrofluoric acid
• SO x sulfur oxides
• NO x nitrogen oxides
• SCR Selective Catalytic Reduction
• SNCR Selective Non-Catalytic Reduction
• SNCR Selective Non-Catalytic Reduction
• it consists in the neutralization of NO x at very high temperatures, around 850 ° C - 1000 ° C, so that a catalyst is not necessary, but which is sometimes incompatible with the process.
• NO x reduction efficiency decreases significantly if the temperature range at the injection point of the reagent is not respected.
• the injection of excess ammonia into the reactor can cause corrosion to downstream equipment and ammonia leakage into the environment.
• the temperature range required for SNCR technology is incompatible with that for desulphurization. Therefore, SCR technology is preferred to combine it within a single plant with desulphurization.
• the desulphurization is generally carried out before the denitrification, so that the fumes at a suitable temperature for the desulfurization must be reheated before the denitrification, which implies a consumption of energy increasing the costs of the process of treatment of the fumes.
• the document EP 2 815 801 describes an example of such an installation, in which fumes generated in a boiler are sent firstly into a treatment unit S0 2 , then into a processing unit SCR. Between the two units, a compressor makes it possible to increase the temperature of the gases at the inlet of the treatment unit SCR.
• the invention provides a method of treating flue gases from a combustion or calcination furnace comprising polluting species including sulfur oxides and nitrogen oxides.
• the method comprises the following steps:
• the method being characterized in that the heated fumes are mixed, after the injection of the nitrogen oxide neutralizing agent, with the cooled fumes after they are brought into contact with the sulfur oxide neutralization agent, the separation residues of the desulfurization reactions and contacting with said catalyst being carried out within a single separation device.
• the method thus makes it possible to clean the fumes of both sulfur oxides and nitrogen oxides in a single installation, while minimizing energy expenditure, and the installation to carry out the process is thus of reduced size.
• the sulfur oxide neutralization agent is, for example, lime.
• the nitrogen oxide neutralizing agent is, for example, ammonia.
• the humidity in the fumes is controlled in order to optimize the desulfurization.
• the invention proposes a plant for treating flue gases from an oven and comprising sulfur oxides and nitrogen oxides, for the implementation of the process as presented above, comprising an exchanger heat exchanger connected to the furnace for cooling the exhaust gases from said furnace, a desulfurization reactor connected to the heat exchanger and wherein the cooled flue gases are contacted with a sulfur oxide neutralizing agent to reduce the latter by desulfurization reactions, a separation device, connected to the desulfurization reactor, and in which residues of the desulfurization reactions are separated from the fumes, an injector of a nitrogen oxide neutralizing agent in at least a part of the separated fumes residues of the desulfurization reactions, and a catalytic device for the denitrification of the fumes, the device for separating the due to the desulphurization reactions being connected to the heat exchanger so that the at least part of the fumes from the residue
• the separation device comprises for example at least one bag filter, a catalyst for denitrification being distributed over the surface of the filter sleeves.
• the separation device comprises at least one baghouse filter, a catalyst for denitrification being placed inside the filter sleeves.
• an installation 100 for the implementation of a method for treating flue gases from a combustion or calcination furnace.
• the plant is particularly suitable for the treatment of fumes from a lime production furnace, the acid gases of which contain, in particular, sulfur oxides (SO x ) and nitrogen oxides (NO x ).
• the installation 100 comprises a heat exchanger 1 of known type.
• the heat exchanger 1 is for example cooling tubes: the lower temperature fluid circulates inside the tubes, while the hotter fluid is in contact with the outer wall of the tubes.
• the heat exchanger 1 therefore comprises two fluid circulation circuits.
• a first flow circuit of the heat exchanger 1 for example the gas flow circuit in contact with the outer wall of the cooling tubes, is connected, on the one hand, to a pipe 1 1 through which the warm fumes from the furnace arrive, and, secondly, a desulphurization reactor 2, for example of the Venturi type, by a conduit 25 for entering the cooled fumes in the reactor 2.
• the reactor 2 comprises an inlet formed by the succession, in the direction of circulation of the cooled fumes, a convergent 5, a neck 4 and a divergent 3.
• the reactor 2 is supplied with a sulfur oxide neutralization agent.
• This sulfur oxide neutralization agent may be lime, sodium bicarbonate, magnesium carbonate, calcium carbonate, or a mixture of at least two of these products.
• the reactor 2 is supplied with fresh lime from a tank 28 which reacts with the sulfur oxides to form salts.
• the fresh lime is fed from the reservoir 28 to the neck 4 of the reactor 2 via a feed line 27.
• the reactor 2 is also fed with hydrated recycled lime.
• the humidity control in the reactor 2 is important. In fact, the moisture content must be sufficiently adjusted so that the lime behaves like a powdery reagent, and does not agglomerate into paste.
• the humidity must be controlled so that the evaporation of the water contained on the surface of the solid particles causes a controlled cooling of the fumes and promotes the absorption and the neutralization of S0 2 , and other possible acids (HCI and HF), while keeping the temperature of the fumes away from their dew point to avoid clogging problems.
• a maximum moisture content by weight of lime of 10% was determined to be adequate.
• the desulphurization reactions in the reactor 2 are thus carried out for a short residence of the fumes in the reactor 2.
• the reaction residues are generally solid salts, such as calcium sulphate (CaSO 3 ) as residues of the sulfur, but also calcium fluoride (CaF 2 ) and calcium chloride (CaCl 2 ).
• the installation 100 comprises a separation device 6, connected to the reactor 2 by a conduit 14 entering a filter of the device 6, and for separating the solid residues reactions including desulphurization, in this case the salts formed and excess lime, gases.
• the separation device 6 comprises at least one bag filter composed of a plurality of filtration modules, through which the fumes pass, the solid residues, and possibly excess lime, being recovered and directed to a reservoir 9 recycling by a pipe 19 recovery.
• the particles which are deposited on the surface of the filter sleeves in the separation device 6 form a cake composed of still active hydrated lime particles forming an additional surface, which makes it possible to continue the acid gas neutralization reaction within the separation device 6. separation device 6 and further increase the efficiency of the process. About 80-95% of the neutralization reaction takes place in reactor 2, and the remainder occurs on the filter sleeves of separation device 6.
• the filter sleeves are said to be catalytic because they include a catalyst for denitrification reactions.
• the sleeves are coated over their entire surface with a layer of a metal catalyst, which increases the contact area with the fumes.
• the catalyst can be placed inside the sleeves.
• the mixture in the recycling tank 9 is called recycled lime.
• the recycled lime is in solid form, making it easy to revalue. All or part of the recycled lime can be re-used in the desulfurization reactor 2.
• the recycled lime is taken by a supply duct 20 to a humidification drum 10, in which water, in a well controlled quantity, enters through a feed 22.
• the recycled lime is moistened, without exceeding maximum moisture content of 10% by weight of lime, is then sent to the reactor 2 of desulfurization by a conduit 23 connected to the neck 4 of the reactor 2 to react again with the acidic pollutants in the fumes.
• Recirculation of lime recycled in reactor 2 maximizes the gas / solid contact, for better use of the reagent and less landfilling residues.
• Residues that are not recycled are dry, which makes it easier to landfill or even re-use as a soil application product.
• the main parameters to ensure a good S0 2 neutralization efficiency are in particular the stoichiometric excess of the hydrated lime fed with respect to the pollutants, the amount of lime recycled and its surface humidity which conditions the lowering of the flue gas temperature, as well as the active surface (BET surface) of hydrated lime particles.
• the fumes at the outlet of the separation device 6 are then directed by a duct 16 to a ventilator 7. This allows in particular to overcome the pressure drop experienced in the filters of the separation device 6. Subsequently, the purified fumes are returned from the fan 7 to a chimney 8 by an outlet conduit 17.
• At least a portion of the fumes separated from the residues of the desulfurization reactions and arriving at the stack 8 is recirculated upstream of the process, to be cleaned of nitrogen oxides by the so-called SCR method.
• a portion of the fumes in the chimney 8 is returned to the heat exchanger 1, in the second flow circuit inside the cooling tubes.
• the recirculated fumes, separated from the residues of the desulfurization reactions are heated by the hot fumes entering the first flow circuit of the exchanger 1, while the hot fumes entering the first circuit are cooled by the recirculated fumes. .
• the energy consumption necessary to bring the fumes to the appropriate temperatures following the steps of their cleaning is thus reduced.
• the recirculated and heated fumes exit the heat exchanger 1 through a contacting conduit 12, distinct from the inlet conduit of the reactor 2, and connected to a reservoir of a nitrogen oxide neutralization agent, for example ammonia.
• a nitrogen oxide neutralization agent for example ammonia.
• ammonia, or urea, or a mixture of these two products can be used.
• the injector 26 of the nitrogen oxide neutralization agent in this example of ammonia, is connected to the contacting conduit 12, so that ammonia mixes with the recirculated fumes and heated in the conduit 12 of contacting.
• the mixture of ammonia and recirculated fumes is combined and mixed with the gas / solids mixture leaving the desulfurization reactor 2 by the junction of the contacting conduit 12 and the inlet conduit 14 in the filter of the device 6, and connecting the reactor 2 to the separation device 6 at a combination point. From the point of combination, the fumes in the filter inlet duct 14 are then a mixture comprising in particular:
• This mixture then enters the separation device 6, with a compatible temperature for denitrification by the SCR method, and comes into contact with the filter of the bag filter.
• the denitrification reactions reduce the nitrogen oxides and ammonia in the fumes to their ionic form to be transformed in particular into nitrogen gas and water vapor.
• the separation device 6 then also serves as a catalytic device for denitrification.
• the fumes are then directed, as before, to the chimney 8, from where the non-recycled portion of these fumes is discharged into the atmosphere through an opening 18.
• the fumes thus removed have pollutants in very low concentration, respecting environmental regulations.
• An advantage of the process is that the residues recovered at the separation device 6, that is to say the salts (CaCl 2 , CaF 2 , CaSO 3 ), are dry, so the recovery of these residues in the market is possible.
• Another advantage is due to the minimal amount of water used to moisturize the hydrated lime in the drum 10; it is not necessary to perform a treatment of liquid effluents, which reduces the amount of equipment and possibly maintenance and operation costs.
• the arrangement of equipment in the implementation of the method also has its advantages. For example, by placing the catalytic baghouses after the desulfurization reactor 2, the majority of SO 2 being removed in the reactor 2, the risks of poisoning the catalyst in the filters of the separation device 6 are significantly reduced.
• filters Another advantage provided by these filters is that catalyst particles can be deposited on the entire surface of their sleeves, which increases the reaction surface for denitrification. Thus, the nitrogen oxides are able to react over the entire length of the filter sleeves with the majority of the ammonia injected upstream of the filters, which avoids its escape to the environment. Likewise, this filtration makes it possible to achieve a high efficiency in the separation of pollutants from the gases, since most of the constituents contained in the starting fumes can be removed.
• the process allows, within a single installation, to achieve desulphurization and denitrification of fumes, limiting energy consumption.
• the method makes it possible to circulate the fumes from the furnace in two parallel circuits, namely a desulfurization circuit and a denitrification circuit, and to adjust the flue gas temperature in each circuit by minimizing the energy consumption.

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• Engineering & Computer Science (AREA)
• Chemical & Material Sciences (AREA)
• Environmental & Geological Engineering (AREA)
• Health & Medical Sciences (AREA)
• Biomedical Technology (AREA)
• Analytical Chemistry (AREA)
• General Chemical & Material Sciences (AREA)
• Oil, Petroleum & Natural Gas (AREA)
• Chemical Kinetics & Catalysis (AREA)
• Treating Waste Gases (AREA)
• Exhaust Gas Treatment By Means Of Catalyst (AREA)

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• 2015
  • 2015-12-10 FR FR1562130A patent/FR3044934B1/fr active Active
• 2016
  • 2016-11-22 EP EP16813003.7A patent/EP3386610A1/de not_active Withdrawn
  • 2016-11-22 US US15/774,601 patent/US20180326351A1/en not_active Abandoned
  • 2016-11-22 CA CA3003371A patent/CA3003371A1/fr not_active Abandoned
  • 2016-11-22 WO PCT/FR2016/053051 patent/WO2017098105A1/fr active Application Filing

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