517 results about "Selective catalytic reduction" patented technology

The invention provides an ammonia-hydrogen engine aftertreatment device and a control method. The post-treatment device comprises an electric heater, an N2O decomposition catalyst, a selective catalytic reducer, an ammonia trapping catalyst, a sensor and a controller, the electric heater is arranged at the exhaust end of the ammonia-hydrogen engine, is powered and controlled by the controller and is used for heating exhaust of the ammonia-hydrogen engine. An N2O decomposition catalyst, a selective catalytic reducer and an ammonia trapping catalyst are sequentially arranged at the rear end of the electric heater; the sensors comprise three temperature sensors, one NOx sensor and one NH3 sensor; the controller receives a temperature signal of the temperature sensor and controls the working state of the electric heater according to the received temperature signal; and the controller receives the concentration signal of NOx and the concentration signal of NH3, and controls the working state of the electric heater according to the concentration signals. According to the invention, the decomposition efficiency of N2O can be improved, and the conversion efficiency of NOx can be improved.

The invention relates to the technical field of flue gas denitrification, and discloses a flue gas baffle system for an SCR (Selective Catalytic Reduction) denitrification device and a use method.The flue gas baffle system is provided with a control system and a matrix flowmeter, a baffle assembly is composed of a plurality of baffle units, each flue is uniformly divided into a plurality of subareas, and each subarea corresponds to a group of adjusting units; and each baffle unit correspondingly controls one subarea of the cross section, so that the technical effects of automatically detecting the flow field at the inlet of the reactor and automatically adjusting the angle of the baffle under different loads or different flow field conditions are realized, the uniformity of the flue gas flow field under different loads is improved, the adaptability of the SCR denitration device to the loads is improved, and the service life of the SCR denitration device is prolonged. The ammonia escape amount when the load or the flow field changes is reduced, and the technical problem that in the prior art, an SCR denitration device cannot adjust the flue gas flow field according to the incoming flow characteristics of flue gas and cannot adjust the flue gas flow field when the performance of an existing flow equalizing device is damaged is solved.

The invention discloses a method for preserving heat of a urea NaOH and Mg (OH) 2 storage cabin, and aims at a ship which is provided with an SCR (Selective Catalytic Reduction) system, an EGR (Exhaust Gas Recirculation) system, an iCER (Initial Continuous Emission Reduction) system and a desulfurization system and needs to store urea, NaOH or Mg (OH) 2. Condensed water of the air conditioning unit is collected and then introduced into the storage cabin in a gravity mode, and the condensed water generation amount and the condensed water temperature of the air conditioning unit are analyzed and calculated. On the premise that the cabin capacity meets the condition, condensate water is used for cooling the urea cabin and then discharged into the clean cabin bottom water cabin, and the cooling capacity of the condensate water is utilized to the maximum extent. In winter or in a cold area, when the air conditioning unit does not need to operate, in order to avoid too low temperature of the solution cabin, the storage cabin can be heated by using the discharged water in the clean cabin bottom water cabin before discharging, so that the storage temperature of the urea, NaOH or Mg (OH) 2 solution is ensured to be 10-35 DEG C.

The invention discloses an integrated treatment method and system suitable for multi-component industrial waste gas, and relates to the technical field of industrial waste gas treatment, and the method comprises the steps of S1, waste gas pretreatment, S2, pre-oxidation and sulfur fixation, S3, thermal oxidation, S4, non-quenching temperature self-adaptive adjustment, S5, selective catalytic reduction denitration, S6, emission and monitoring, and S7, intelligent dynamic system control. The gradient temperature field of the heat storage ceramic body is used for providing accurate and stable air inlet temperature for the SCR reaction, an independent quenching device is omitted, and therefore the comprehensive energy consumption and the operation cost of the system are greatly reduced, and by additionally arranging the pre-oxidation layer and adopting the dual-function SCR catalyst, the heat storage effect of the system is greatly improved. The system effectively realizes advanced fixation of organic sulfur and efficient removal of nitrogen oxides, dynamically adjusts the ammonia injection amount and combustion intensity, ensures that the system can still maintain extremely high treatment efficiency and stability under flow fluctuation and complex working conditions, reduces ammonia escape to the greatest extent, and is convenient to use.

An exhaust aftertreatment system (10) in the exhaust stream of an internal combustion engine (12) that is at least partially powered by an alcohol fuel is permeable to an exhaust stream containing nitrogen oxides as well as an alcohol and / or formaldehyde. The exhaust aftertreatment system (10) comprises a metering device (14) for metering ammonia into the exhaust stream, a first SCR catalyst (16), and a second SCR catalyst (18), wherein the first SCR catalyst (16) is arranged in the exhaust stream downstream of the metering device (14) and is configured to generate a treated exhaust stream from the exhaust stream of the internal combustion engine (12) that contains nitrogen oxides and at least one nitrogen-containing hydrocarbon compound.The second SCR catalyst (18) is arranged in the exhaust stream downstream of the first SCR catalyst (16) and is designed to reduce the nitrogen oxides contained in the generated treated exhaust stream by consuming the nitrogen-containing hydrocarbon compound contained in the generated treated exhaust stream. Furthermore, a method for exhaust aftertreatment and the use of an exhaust aftertreatment system (10) are specified.

An exhaust aftertreatment system (10) in the exhaust stream of an internal combustion engine (12) that is at least partially powered by an alcohol fuel is permeable to an exhaust stream from the internal combustion engine (12) containing nitrogen oxides as well as an alcohol and / or formaldehyde. The exhaust aftertreatment system (10) comprises an oxidation catalyst (14) for removing methanol and formaldehyde from the exhaust stream, an SCR catalyst (18), and a metering device (16) for metering ammonia into the exhaust stream, wherein the oxidation catalyst (14) is arranged in the exhaust stream upstream of the SCR catalyst (18). The metering device (16) is arranged in the exhaust stream upstream of the SCR catalyst (18) and upstream or downstream of the oxidation catalyst (14). Furthermore, a method for exhaust aftertreatment and the use of the exhaust aftertreatment system (10) are specified.

A non-transitory computer-readable media having computer-readable instructions stored thereon that, when executed by at least one controller, cause the at least one controller to cause a first doser to cease dosing a first reductant portion of a reductant to a first exhaust portion of exhaust upstream of a first catalyst member disposed in a first leg of a selective catalytic reduction (SCR) system. The instructions can cause the at least one controller to cause a second doser to dose a second reductant portion of the reductant to a second exhaust portion of the exhaust upstream of a second catalyst member disposed in a second leg of the SCR system. The instructions can cause the at least one controller to determine a first conversion efficiency of the first leg while the first doser is not dosing the first reductant portion and the second doser is dosing the second reductant portion.

A system, method, and apparatus for detecting sensor tampering are provided. An aftertreatment system includes a first train having a first selective catalytic reduction (SCR) system, a first doser, and a first NOx sensor; a second train having a second SCR system, a second doser, and a second NOx sensor; and a controller. The controller determines satisfaction of activation conditions. The controller doses reductant to the first and second SCR systems. The controller determines the NOx levels of the first SCR system and the second SCR system. The controller adjusts the dosing of the first SCR system for a period of time. The controller measures the NOx levels of the first SCR system and the second SCR system. The controller determines a difference between the third and first NOx levels and a difference between the fourth and second NOx levels.The control generates an indication as to whether the first NOx sensor is displaced.

The invention discloses a gas turbine SCR denitration ammonia injection automatic adjusting system and method, and relates to the technical field of gas turbine flue gas denitration, and the method comprises the following steps: periodically obtaining first difference value data and second difference value data; wherein the first difference value data is obtained by calculating the difference value between the outlet NOx concentration data and a preset NOx concentration target value; the second difference value data is obtained by calculating the difference value between the NOx concentration data before denitration and a preset NOx concentration target value; and performing double-component decomposition including a baseline component and a transient component on the first difference data, and recombining a double-component decomposition result to obtain unit area ammonia gas amount data. According to the scheme, the steady-state deviation and the dynamic disturbance are separated through error decomposition and variance correction, the problem of ammonia spraying amount calculation errors caused by the fact that the steady-state deviation and the transient deviation are not distinguished in the prior art is solved, the weight of the transient component is dynamically adjusted through variance correction, and the ammonia spraying amount calculation accuracy is improved. And the generation process of the unit area ammonia gas amount data can respond to the long-term operation requirement of the system.

The invention discloses an anti-alkali metal poisoning SCR (Selective Catalytic Reduction) catalyst and a preparation method and application thereof, and belongs to the field of catalysts for atmospheric governance, the SCR catalyst comprises the following components in percentage by mass: 80%-90% of TiO2, 0.5%-1.5% of V2O5, 3%-5% of WO3 and 3%-10% of a cocatalyst; the cocatalyst comprises one or two of zirconium phosphate and titanium phosphate. The SCR catalyst provided by the invention is high in targeting property and remarkable in alkali metal poisoning resisting effect. TiO2 is used as a main carrier, V2O5 provides a main catalyst active component, WO3 can improve the thermal stability and acidity of the catalyst, a cocatalyst loses activity after capturing alkali metal, and an effective chemical barrier is constructed by sacrificing the cocatalyst; the path that alkali metal ions continue to diffuse into the coating and react with key V-OH acidic sites is blocked, and the alkali poisoning resistance is qualitatively improved, so that the denitration activity of the catalyst is preserved.

The invention discloses a national sixth heavy diesel vehicle SCR failure test method based on a remote monitoring platform, and belongs to the technical field of diesel vehicle emission control, and the test method comprises the following specific steps: I, inputting various data of a vehicle within a preset time, and carrying out the validity verification of the input various data of the vehicle; iI, collecting real-time operation parameters of each vehicle, and classifying and identifying working conditions corresponding to each vehicle according to the operation parameters of each vehicle; iII, extracting various data of the vehicle passing the validity verification, and matching the data with dynamic threshold libraries corresponding to different vehicle working conditions; according to the invention, the fault identification accuracy can be improved to 88% or more, the troubleshooting time is greatly shortened, and meanwhile, through a three-stage progressive alarm mechanism, full-coverage monitoring from slight abnormity to serious faults is realized, so that the service life of the SCR system is prolonged by 30% or more, and the deployment cost is reduced by 60% or more.

The invention discloses a denitration system capable of automatically adjusting an ammonia spraying strategy, which comprises a data sensing layer and an execution layer, the data sensing layer comprises a plurality of measuring devices arranged at an inlet and an outlet of an SCR (Selective Catalytic Reduction) reactor, the execution layer comprises a plurality of ammonia spraying grids arranged along the section of a flue in a partitioned manner, and each partition corresponds to an independent ammonia spraying branch pipe; an adjustable flow control valve is arranged on each ammonia spraying branch pipe; the control layer is in communication connection with the data sensing layer and the execution layer, and the control layer comprises an advanced controller and is configured to receive real-time data of the data sensing layer and optimize the real-time data on the basis of a preset denitration model and an optimization algorithm; calculating the distribution uniformity index of the NOx concentration at the outlet of the SCR reactor and the target ammonia gas flow required by each partition of the plurality of ammonia spraying grids; and the distributed PID controller is connected with the advanced controller and is configured to receive the target ammonia gas flow of each partition and generate a control signal to drive the corresponding flow control valve, and the total ammonia consumption can be remarkably reduced under the same denitration efficiency.

The invention relates to the technical field of SCR (Selective Catalytic Reduction) denitration system equipment, in particular to an SCR denitration self-heating anti-blocking ammonia spraying nozzle and equipment, the ammonia spraying nozzle is provided with a double-layer sleeve structure, so that a heating cavity for mounting a heating device is formed between two sleeves; the inner pipe conveys mixed gas of ammonia gas and air, generation and attachment of viscous substances such as ammonium bisulfate are effectively avoided through heating of the heating device in the heating cavity, guide vanes are arranged in a nozzle at the end of the inner pipe, dust, ammonium salt and other substances attached to the position close to the nozzle are thrown away through centrifugal force, and the dust, the ammonium salt and other substances are prevented from being accumulated to block the nozzle; the ultrasonic generator is arranged on the outer pipe, so that ultrasonic waves can be emitted regularly, the inner pipe generates tiny vibration, dust, ammonium salt and other substances attached to the surface of the inner pipe are vibrated off, the self-cleaning function is achieved, the risk that the spray head is blocked is further reduced, and the problem that the ammonia spraying spray head is prone to being blocked is fundamentally solved.

The invention relates to the field of nitrogen oxide treatment, and particularly provides preparation and application of a Fe-Mn / NbOPO4 catalyst for improving water resistance and sulfur resistance of NH3-SCR (selective catalytic reduction) reaction. The preparation method comprises the following steps: 1, preparation of an NbOPO4 carrier: mixing and stirring a niobium source and a phosphorus source, dropwise adding ammonia water, filtering and washing to obtain a precipitate, further adding a CTAB / H2O solution, adjusting the pH value with H3PO4, carrying out hydrothermal aging in a reaction kettle, and finally filtering, washing, drying and calcining; and 2, loading Fe and Mn active components, dissolving an iron source and a manganese source in water by adopting a wet impregnation method, adding the NbOPO4 carrier, stirring, carrying out rotary evaporation, drying and calcining. When the air speed is 60000mL. G <-1 >. H <-1 >, the NOx conversion rate in the temperature range of 75-297 DEG C reaches 90% or above, and in a water-resistant and sulfur-resistant performance test of 5vol.% H2O and 100ppm SO2, the reaction activity is almost not obviously reduced. The SCR reaction temperature window of the manganese-based catalyst is widened, the water resistance and sulfur resistance of the manganese-based catalyst are effectively improved, and the manganese-based catalyst has wide application prospects.

The invention discloses an ammonia spraying real-time feedback regulation method based on an SCR (Selective Catalytic Reduction) denitration system, which comprises the following steps: dividing a cross section partition on an outlet flue of the SCR denitration system, and synchronously collecting a flue gas sample on the cross section partition; dynamically adjusting the flow of a cooling medium of a gas cold air coil pipe through a self-adaptive fuzzy PID control algorithm, and cooling and dehumidifying each path of collected flue gas sample to obtain a dry flue gas sample; the concentration of each path of dry flue gas sample is analyzed in real time, and the optimal ammonia spraying valve opening strategy of each cross section partition is predicted by combining the ammonia spraying amount of each path, the flue gas flow of the SCR denitration system, the unit load and the ammonia escape concentration and adopting a multivariable model prediction control algorithm; and according to the predicted optimal ammonia injection valve opening strategy of each cross section partition, the ammonia injection valves of the corresponding cross section partitions are adjusted, and real-time feedback adjustment of ammonia injection is achieved.

The invention discloses an H < 2 >-SCR and NH3-SCR double-path parallel connection ammonia hydrogen internal combustion engine aftertreatment system and a control method, the treatment system comprises a first catalytic reaction branch, a second catalytic reaction branch, a third catalytic reaction branch and a fourth catalytic reaction branch, the inlet end of the first catalytic reaction branch is connected to an exhaust pipe of an ammonia hydrogen internal combustion engine, and the first catalytic reaction branch is selectively communicated with the exhaust pipe of the ammonia hydrogen internal combustion engine; wherein an ammonia gas selective catalytic reducer is arranged on the first catalytic reaction branch; the inlet end of the second catalytic reaction branch is connected to an exhaust pipe of the ammonia-hydrogen internal combustion engine and selectively communicates with the exhaust pipe of the ammonia-hydrogen internal combustion engine; a hydrogen selective catalytic reducer is arranged on the second catalytic reaction branch; the inlet end of the anti-escape treatment device is selectively communicated with the outlet end of the first catalytic reaction branch or the outlet end of the second catalytic reaction branch; wherein the anti-escape treatment device comprises a hydrogen oxidation catalyst, an ammonia escape catalyst and an N2O decomposition catalyst which are connected in sequence.

The invention discloses an ammonia escape control system of a selective catalytic reduction denitration system, and relates to the technical field of flue gas denitration of thermal power generating units. Accurate data support is provided for fine adjustment of the ammonia spraying amount by collecting and feeding back the nitrogen oxide concentration at the key position in the flue, so that the area with low local denitration efficiency is identified; meanwhile, the ammonia spraying amount is controlled through independent ammonia supply mother pipes and independent electric control valves on the basis of a plurality of ammonia spraying areas arranged in a matched mode of the measuring unit, a closed-loop control system with the regional nitrogen oxide concentration as a core feedback variable is formed, and each ammonia spraying area can respond independently; the problem of excessive or insufficient ammonia caused by traditional'one-step 'ammonia spraying is avoided, the ammonia spraying uniformity is improved, and the ammonia escape rate and the ammonia salt accumulation degree are reduced.

The invention provides a catalyst composition, including a mixture of catalytically active particles and a magnetic material, such as superparamagnetic iron oxide nanoparticles, capable of inductive heating in response to an applied alternating electromagnetic field. The catalytically active particles will typically include a base metal, platinum group metal, oxide of base metal or platinum group metal, or combination thereof, and will be adapted for use in various catalytic systems, such as diesel oxidation catalysts, catalyzed soot filters, lean NOx traps, selective catalytic reduction catalysts, ammonia oxidation catalysts, or three-way catalysts. The invention also includes a system and method for heating a catalyst material, which includes a catalyst article that includes the catalyst composition and a conductor for receiving current and generating an alternating electromagnetic field in response thereto, the conductor positioned such that the generated alternating electromagnetic field is applied to at least a portion of the magnetic material.

The utility model provides cement kiln tail high-temperature low-dust SCR (Selective Catalytic Reduction) denitration equipment capable of realizing off-line ash removal, which comprises a high-temperature bag dust collector, a denitration reactor, a flue, more than two compartments, a flap valve assembly and an ash removal assembly for carrying out ash removal treatment on a filter bag to be cleaned of the high-temperature bag dust collector, all the compartments are arranged at the top of the high-temperature bag dust collector, the denitration reactor is arranged beside the high-temperature bag dust collector, the flue is located between the compartments on the two sides, and the flue is communicated with an air inlet of the denitration reactor; the air inlets of the sub-chambers are communicated with the corresponding high-temperature bag dust collectors, and the flap valve assemblies are located at the air outlets of the sub-chambers and used for communicating or blocking the air outlets of the sub-chambers with the flue; the flap valve assemblies are closed, the air outlets of the sub-chambers are blocked from the flue, the sub-chambers are unloaded, and smoke does not circulate in the sub-chambers, so that off-line ash removal of the high-temperature bag dust collector is achieved, and the single-chamber ash removal effect is more thorough.

The invention discloses a functional composite pore-forming agent, a sulfur-resistant denitration catalyst and a preparation method of the functional composite pore-forming agent and the sulfur-resistant denitration catalyst, and belongs to the technical field of selective catalytic reduction (SCR) of flue gas. According to the invention, the active component is prepared by adopting equivalent-volume impregnation; preparing a functional composite pore-forming agent containing citric acid and / or polyethylene glycol and a sulfur-resistant component MxOy-SiO2; the preparation method comprises the following steps: mixing and kneading an active component, a forming auxiliary agent and a functional composite pore-forming agent, performing extrusion molding, and performing roasting, phase forming and shaping according to a procedure, so that MxOy-SiO2 is deposited and fixed in situ on a new pore wall. The obtained strip-shaped catalyst has a high specific surface area and a pore wall sulfur-resistant functional layer, can effectively inhibit deposition of ABS in pores and slow down poisoning of SO2 to manganese-based sites, shows high NOx conversion rate and stability in an ultralow temperature interval of 80-320 DEG C, is suitable for denitration treatment of sulfur-containing complex flue gas such as steel, coking and cement, and has good industrial implementability.

The present invention relates to a zeolitic material having an AEI-type framework structure comprising SiO2, Al2O3 and B2O3, wherein the Al:B molar ratio of the zeolitic material, is comprised in the range of from 3 to 500, and wherein the zeolitic material displays an Si:(Al+B) molar ratio of the zeolitic material, which is comprised in the range of from 2 to 11. The present invention also relates to a process for the preparation of the zeolitic material according to the present invention, to a process for the treatment of NOx by selective catalytic reduction and to an apparatus for the treatment of a gas stream containing NOx, as well as to the use of a zeolitic material according to the present invention.

Systems are provided including a selective catalytic reduction catalyst structured to receive first exhaust gas from a first fuel source of a dual fuel engine system and second exhaust gas from a second fuel source of the dual fuel engine system, a first fuel of the first fuel source differing from a second fuel of the second fuel source, an ammonia slip catalyst positioned downstream of the selective catalytic reduction catalyst to receive a flow of exhaust gases from the selective catalytic reduction catalyst without an intervening catalyst, and an oxidation catalyst positioned downstream of the ammonia slip catalyst to receive the flow of exhaust gases from the ammonia slip catalyst without an intervening catalyst.

The invention discloses a power grid SCR prediction method and device based on a few-mark data adversarial network and a medium, and the method comprises the steps: collecting control error data of a power grid system from a grid-connected or off-grid moment to a stable moment under different SCRs and different load grid-connected and off-grid working conditions in a historical time period, calculating an evaluation index through the control error data, and constructing a sample set; training and verifying the SCR estimation network by using the obtained sample set to obtain a trained SCR estimation network; the input of the SCR estimation network is each group of data in the sample set, namely ISE, ISTE, IAE, ISAE and load after weight factors are introduced, and the output of the SCR estimation network is a predicted SCR value; a trained SCR estimation network is deployed in simulation, an evaluation index is calculated according to data collected in real time, the evaluation index and a load are input into the trained SCR estimation network for real-time network training, and the purpose of outputting an SCR estimation value at any moment is achieved.

The invention relates to the technical field of boilers, in particular to a circulating fluidized bed boiler, which is provided with an SNCR (selective non-catalytic reduction) and SCR (selective catalytic reduction) combined device, the SNCR and SCR combined device comprises an SNCR device and an SCR device, the SNCR device comprises an ammonia water spray pipe arranged in an area with the temperature of 800 DEG C, ammonia water is sprayed into tail gas through the ammonia water spray pipe, the ammonia water is gasified and subjected to contact reaction with NOx, and the concentration of NOx at an outlet of a cyclone separator is controlled to be less than 40mg / Nm < 3 >. The SCR device comprises an SCR reactor arranged in an area of 320-420 DEG C, NOx and ammonia gas are subjected to catalytic reaction in the SCR reactor, the concentration of NOx is reduced to be smaller than 25 mg / Nm < 3 > under the action of a catalyst, the concentration of NOx after reaction is reduced to be 20 mg / Nm < 3 >, the content of NH3 in flue gas is 45 mg / Nm < 3 >, the NOx enters an ammonia-process desulfurization tower along with the flue gas and serves as supplement of a desulfurization agent for ammonia-process desulfurization, ammonia escape can be controlled to be smaller than 1 mg / Nm < 3 > after ammonia-process desulfurization, and the ammonia escape can be controlled to be smaller than 1 mg / Nm < 3 > after ammonia-process desulfurization. The environment-friendly emission standard is met.

This invention discloses a passive adsorption-selective catalytic reduction (CCR) device for diesel vehicles, comprising an electronically controlled nozzle, a first mixing chamber, a pre-catalytic oxidation-reduction chamber, a second mixing chamber, and a post-catalytic oxidation-reduction chamber arranged sequentially. The first mixing chamber includes a first urea solution inlet, a V-shaped breaker wall, and a W-shaped bottom mixing chamber. The V-shaped breaker wall is fixed to the rear wall of the first urea solution inlet pipe. The W-shaped bottom mixing chamber includes an inner cavity and an outer cavity. The inner cavity wall has staggered array openings, and the inner and outer cavities are connected through these openings. A guide wall structure is connected to the outermost pipe at the end of the first mixing chamber. The CCR chamber is connected to the end of the guide wall, and a three-zone integrated catalyst is located inside the CCR chamber. This invention solves the problems of severe NOx escape during the cold start phase, system complexity, and low-temperature urea crystallization in existing selective catalytic reduction technologies.

The invention relates to an In (at) H-Beta / Fe3O4 catalyst, a preparation method thereof and application of the In (at) H-Beta / Fe3O4 catalyst in methane selective catalytic reduction of nitric oxide, and the preparation method comprises the following steps: firstly, carrying out ion exchange reaction on an H-Beta molecular sieve and an indium precursor solution, and calcining to obtain an In (at) H-Beta precursor; and mixing the In-coated H-Beta precursor with the Fe3O4 dispersion liquid, and calcining to obtain the In-coated H-Beta composite material. Compared with the prior art, the method has the advantages that molecular sieve confinement loading of indium species and surface modification synergy of the iron oxide nanoparticles are realized by adopting a hierarchical loading strategy, and the obtained catalyst shows excellent activity and water-resistant stability in CH4-SCR reaction, and has adjustable metal dispersity and strong metal-carrier interaction; a new scheme is provided for the development of a catalyst for efficiently resisting water poisoning, and the catalyst has a remarkable industrial application value.

An EATS for converting NOx emissions in exhaust gas from an engine, the EATS comprising: a fluid passage (40) for providing a fluid path for the exhaust gas; a selective catalytic reduction, SCR, catalyst (32) arranged in the fluid passage, the SCR catalyst being configured to store ammonia; an injector (34) configured to inject a reducing agent to provide ammonia to the SCR catalyst, the injector being arranged upstream of the SCR catalyst; a fluid flow inducer (56, 58) configured to induce a fluid flow in at least a portion of the fluid passage when the engine is off; and a control device (17) configured to pre-condition the EATS by injecting a reducing agent into the fluid passage before the engine is started and to transport the reducing agent into the SCR catalyst by the induced fluid flow, thereby storing ammonia in the SCR catalyst.

The present invention relates to a process for preparing a catalyst for the selective catalytic reduction of nitrogen oxide comprising, among other steps, preparing a second aqueous mixture comprising water and an iron salt; and disposing the second mixture on the substrate obtained according to (ii), comprising a coating comprising a zeolitic material comprising copper, over y % of the substrate axial length from the inlet end to the outlet end of the substrate, wherein y is in the range of from 10 to x, obtaining a substrate comprising, in a first zone, the coating comprising a zeolitic material comprising copper and over y % of the substrate axial length an iron salt; and, if x>y, in a second zone extending from y % to x % of the substrate axial length from the inlet end to the outlet end, the coating comprising a zeolitic material comprising copper.

The invention discloses a thermal redundancy method for a reducing agent supply system of an SCR (Selective Catalytic Reduction) system, which comprises a supply system and is characterized in that two paths of pipelines for supplying reducing agents in parallel are arranged, a hand valve, a filter, an electromagnetic valve, a supply pump and a check valve are respectively arranged on each row of reducing agent supply pipelines, and maintenance of one path of reducing agent supply pipeline and operation of the other path of reducing agent supply pipeline are realized; the electric control system is connected with the supply system hardware, when any one supply pipeline runs, the supply of the reducing agent is abnormal, the electric control system gives an alarm and automatically controls the supply system to be switched to the other supply pipeline to run at the same time, and troubleshooting and system maintenance under the condition that the supply system runs uninterruptedly are achieved; according to the thermal redundancy method for the reducing agent supply system of the SCR system, troubleshooting and system maintenance under the condition of uninterrupted operation of the supply system are achieved, normal operation of the supply system of the SCR system is effectively guaranteed, and the problem that NOx emission exceeds the standard is avoided.

The invention relates to an exhaust gas treatment system comprising, in an upstream to downstream order, a first particulate filter, a device for injecting a nitrogenous reductant and a selective catalytic reduction (SCR) assembly, wherein the system further comprises a second particulate filter arranged downstream of the device for injecting a nitrogenous reductant.