Modeling and simulation of marine SCR system based on Modelica

With the increasing awareness of global marine environmental protection, the emission of ship exhaust pollutants is strictly restricted. Selective catalytic reduction (SCR) technology is the mainstream technology to reduce ship NOx emission and make it meet IMO tier III regulations. A SCR reaction kinetic model based on Modelica language was established by Dymola software to predict the denitration efficiency, ammonia slip rate, and other parameters of SCR system. According to the functional structure of marine SCR system, the SCR system model is divided into urea injection module, mixer module, and SCR reactor module. The model was verified by SCR system bench test of WD10 diesel engine, which proved that the model can preferably reflect the actual situation. Using the established model, the effects of temperature, flow rate, NH3/NOx Stoichiometric Ratio (NSR), and cell density on the denitration performance of SCR system were analyzed. The results showed that the exhaust gas temperature and NSR have a great influence on the denitration efficiency. The injection amount of urea solution in marine SCR system should be based on the exhaust gas temperature and exhaust flow rate.

Correction: Promotional mechanism of enhanced denitration activity with Cu modification in a Ce/TiO2–ZrO2 catalyst for a low temperature NH3-SCR system

Correction for ‘Promotional mechanism of enhanced denitration activity with Cu modification in a Ce/TiO2–ZrO2 catalyst for a low temperature NH3-SCR system’ by Wei Zhang et al., RSC Adv., 2022, 12, 378–388, DOI: 10.1039/d1ra06325a

Promotional mechanism of enhanced denitration activity with Cu modification in a Ce/TiO2–ZrO2 catalyst for a low temperature NH3-SCR system

Probable surface NH3-SCR reaction mechanism over CuCe/TiO2-ZrO2 catalyst is proposed to follow the E–R mechanism and the L–H mechanism, while the E–R mechanism dominates in the reaction and the oxidation of NO closes the catalytic cycle.

Improving the NOx reduction performance of an Euro VI d SCR System in real-world condition via nonlinear model predictive control

This paper deals with the possibility of improving the urea dosage control for the Selective Catalytic Reduction Systems (SCR) of an Euro VI d diesel light commercial vehicle in order to increase [Formula: see text] after-treatment reduction performance. To this aim, first, we assess the effective emissions abatement performance for the appraised diesel vehicle via real-world experimental campaign, carried out according to the Real Driving Emissions (RDE) tests on urban, extra-urban and motorway road sections in Naples, Italy. Based on these real-world data, we derive a parameterized control-oriented model for the SCR system which is, then, exploited for the designing of an alternative urea injection logic which could be able to maximize the [Formula: see text] reduction efficiency while minimizing tailpipe ammonia slip. Specifically, the optimal AdBlue injection rate is designed according to a Nonlinear Model Predictive Control Approach which allows obtaining a proper trade-off between the [Formula: see text] abatement and the urea overdosing problem. The effectiveness of the proposed controller is evaluated by comparing the performance assessed for the appraised SCR system during the experimental tests with the ones achievable if the Euro VI diesel would be equipped with the proposed control strategy. Numerical simulation discloses the effectiveness of the NMPC controller in ensuring improved [Formula: see text] reduction with performance complying with the emissions norms, main in avoiding excessive ammonia slip and in guaranteeing a reduced feed ratio w.r.t. to the standard industrial SCR controller mounted on the vehicle.

Melting and Heat Transfer Characteristics of Urea Water Solution According to a Heating Module’s Operating Conditions in a Frozen Urea Tank

The urea-selective catalytic reduction (SCR) system, a nitrogen oxide reduction device for diesel vehicles, is a catalytic system that uses urea water solution (UWS) as a reducing agent. This system has a relatively wide range of operating temperatures. However, the freezing point of the reducing urea solution used in this system is −11 °C. When the ambient temperature dips below this freezing point in winter, the solution may freeze. Therefore, it is important to understand the melting characteristics of frozen UWS in relation to the operating conditions of the heating device to supply the minimum amount of aqueous solution required by the system in the initial stage of normal operation and startup of the urea–SCR system. In this study, we artificially froze a liquid solution by placing it along with a heating module in an acrylic chamber to simulate a urea solution tank. Two types of heating modules (P120 and P160) consisting of two heating elements and heat transfer bodies were used to melt the frozen solution. The melting characteristics of the frozen solution were observed, for example, changes in the temperature distribution around the heating module and the cross-sectional melting shape with the passage of time since the start of the power supply to the heating module. The shape of melting around the heating module differed depending on the level of UWS relative to the heater inside the urea tank. In case 1, it melted in a wide shape with an open top, and in case 2, it melted in a closed shape. This shape change was attributed to the formation of internal gaseous space due to volume reduction during melting and the heat transfer characteristics of the fluid and solid substances.

Research on Numerical Simulation and Optimization of SCR Flow Field of 200MW Coal-Fired Unit

In this paper, Computational Fluid Dynamics (CFD) and Flow Model Test are applied to study the flow field of 200MW coal fired power plant, then the optimization program is proposed. Firstly, this paper summarizes some essential design points for SCR reactor system with different structures and different characteristic. Then, the initial flow field of the SCR reactor was simulated to find the defect by the Fluent. Then, optimize the flow fields of velocity of SCR system by adding splitters. In order to improve the mixing degree of flue gas and ammonia, Ammonia Injector Grids (AIG) was designed on the basis of the structure of SCR reactor. Considering the pressure loss and installation space were within allowed limits, a new static mixer was designed to optimize the flow fields of concentration. Through the shift of size, angle and altitude of the static mixer, this paper got a best design project. The research results can provide theoretical support and engineering guidance for the transformation and optimization of the new SCR denitration engineering reaction system.

Intelligent Calculation Method and Algorithm Optimization of Consumption Reducing for SCR and SNCR in Denitriation System

Since the environmental laws have been more and more strict about pollutants emissions of thermal power plant, SNCR and SCR system seems to be typical configuration. However the ammonia consumption calculation differs from different designers. In this paper the popular and experienced calculation method is introduced for thermal power plant dinitriation system.