Research on prediction model of formation temperature of ammonium bisulfate in air preheater of coal-fired power plant

Ammonium bisulfate(ABS)is a viscous compound produced by the escape NH_(3) in the NO reduction process and SO_(3) in the flue gas at a certain temperature,which can cause the ash corrosion of the air preheater in coal-fired power plants.Therefore,it is essential to study the formation temperature of ABS to prevent the deposition of ABS in air preheaters.In this paper,the SO_(3) reaction kinetic model is used to analyze the SO_(3) generation process from coal combustion to the selective catalytic reduction(SCR)exit stage,and the kinetic model of NO reduction is used to analyze the NH_(3) escape process.A prediction model for calculating the ABS formation temperature based on the S content in coal and NO reduction parameters of the SCR is proposed,solving the difficulty of measuring SO_(3) concentration and NH_(3) concentration in the previous calculation equation of ABS formation temperature.And the reliability of the model is verified by the actual data of the power plant.Then the influence of S content in coal,NH_(3)/NO_(x) molar ratio,different NO_(x) concentrations at SCR inlet,and NO removal efficiency on the formation temperature of ABS are analyzed.

False Data Injection Attacks Detection in Power System Using Machine Learning Method

False data injection attacks (FIDAs) against state estimation in power system are a problem that could not be effectively solved by traditional methods. In this paper, we use four outlier detection methods, namely one-Class SVM, Robust covariance, Isolation forest and Local outlier factor method from machine learning area in IEEE14 simulation platform for test and compare their performance. The accuracy and precision were estimated through simulation to observe the classification effect.

磁性纳米Fe_3O_4增强超声/H_2O_2体系降解左氧氟沙星的实验研究(英文)

Fe3O4 magnetic nanoparticles(MNPs) were synthesised, characterised, and used as a peroxidase mimetic to accelerate levofloxacin sono-degradation in an ultrasound(US)/H2O2 system. The Fe3O4 MNPs were in nanometre scale with an average diameter of approximately 12 to 18 nm. The introduction of Fe3O4 MNPs increased levofloxacin sono-degradation in the US/H2O2 system. Experimental parameters, such as Fe3O4 MNP dose, initial solution p H, and H2O2 concentration, were investigated by a one-factor-at-a-time approach. The results showed that Fe3O4 MNPs enhanced levofloxacin removal in the p H range from 4.0 to 9.0. Levofloxacin removal ratio increased with Fe3O4 MNP dose up to 1.0 g·L-1and with H2O2 concentration until reaching the maximum. Moreover, three main intermediate compounds were identified by HPLC with electrospray ionisation tandem mass spectrometry, and a possible degradation pathway was proposed. This study suggests that combination of H2O2, Fe3O4 MNPs and US is a good way to improve the degradation efficiency of antibiotics.

Effect of secondary air on NO emission in a 440 t/h circulating fluidized bed boiler based on CPFD method

The 440 t/h circulating fluidized bed boiler was numerically simulated by the Computational Particle Fluid Dynamics(CPFD)method.The combustion characteristics of circulating fluidized bed boiler and the effect of secondary air on NO emission were investigated.The full-scale three-dimensional model of a 440 t/h circulating fluidized bed boiler was established.The rationality of the grid was validated by the experimental data of material layer resistance.The accuracy of the simulation was validated by measuring the temperature of each measuring point in the dense phase area.The combustion conditions in the furnace under different setting modes were simulated.The effects of secondary air rates on NO formation in fluidized bed were predicted.The results show that when the secondary air rate increases to 27%,the proper secondary air rate has a positive effect on the inhibition of NO generation,and the proper strengthening of the central air supply will improve the permeability of the secondary air and make the combustion more uniform and stable.When the secondary air rate increases to 33%,excessive improvement of air classification and central air distribution will affect the stability of circulating fluidized bed operation.Therefore,air classification and strengthening of central air supply can be used together to inhibit the generation of NO.

Microstructural change and stress rupture property of Nimonic 105 superalloy for advanced ultra-supercritical power plants

Microstructural change,stress rupture property,deformation and fracture mechanisms of Nimonic 105 superalloy at 750℃have been studied.Experimental results showed that the stress rupture strength of the alloy at 750℃ for 10^(5)h is about 200 MPa.γ'precipitates and M_(23)C_(6)carbides grew gradually with prolonging the rupture time,while no significant change was observed in MC carbide morphology.After stress rupture test at 750℃ and 250 MPa for 23,341 h,a transition from spherical to cuboidal morphology of γ'precipitates was found,and nearly continuous chains of M_(23)C_(6)carbides formed on the grain boundary.Orowan looping and strongly coupled dislocation pairs cutting and microtwinning were the dominant deformation mechanisms at 750℃ and 350-450 MPa,while the main deformation mode was Orowan looping at 750℃ and 250 MPa.The failure of the alloy was mainly attributed to the nucleation,growth and interlinkage of voids.

Effect of Hydrogen-Rich Fuels on Turbulent Combustion of Advanced Gas Turbine

The effect of high hydrogen fuel on turbulent combustion in advanced gas turbine combustor with our newly designed arrayed-vanes premixer was studied by large eddy simulation(LES).The dynamic Smagorinsky model is used to calculate the subgrid stress.Finite-rate chemistry is included using a four steps mechanisms.A thickened flame model was used to deal with the reaction rate.The transport and thermal properties are obtained by CHEMKIN packages.The results show that with the increase of hydrogen content,the wake recirculation zone and central toroidal recirculation zone separate.The turbulent fluctuations of H_(2)/air flame first decreases and then increases.For the response of turbulent flame,the results show that the flame brush is narrow and short with the increase of hydrogen content.When the hydrogen content is low,the syngas/air flame can also propagate in the high-speed flow.Therefore,for different flames,the position of outer propagating flame is almost the same.The results also show that the fluctuation of flame intensity increases with the increase of hydrogen content.Although the increase of hydrogen content shortens the chemical reaction time and suppresses the perturbation of turbulent eddies,the cellular instability may further enhance the fluctuation of flame intensity.

Service Restoration of Distribution Systems Under Distributed Generation Scenarios

A novel extended network for service restoration optimization problem under distributed generation scenarios is presented in which the main network restoration and DG island restoration problems are integrated into a unified spanning-tree problem.The proposed technique is aimed to realize synchronous optimization of both main network and island restorations,and thus ensure the algorithms that are used find the global optimization solution.A fast loop-breaking technique is also proposed in this paper.Based on the circuit-branch correlation matrix,the proposed technique can break the loops in the distribution systems through matrix operations that significantly improve calculation speeds.Simulation results verify the correctness and advantage of the proposed algorithms:the proposed integrated optimization strategy based on the extended network has better performance compared with a two-step restoration strategy;also,the proposed loop-breaking technique has faster calculation speed compared with prim algorithm and DFS based on adjacentmatrix.