CFD Simulation of a Bag Filter for a 200MW Power Plant

The combustion of pulverized coal inevitably produces dust and other harmful substances.For these reasons,the optimization of de-dusting procedure and equipments is an aspect of crucial importance towards the final goal of making this source of energy more sustainable.In the present work,the behaviour of a“bag filter”is simulated using Computational Fluid Dynamics(CFD).More specifically,three possible approaches are used,differing with respect to the level of fidelity and the partial utilization of empirical data.The outcome of these simulations is mutually compared and finally discussed critically in the light of available experimental results.

A Research on the Flow Characteristics of a Splitter-Based Water Cooling System for Computer Boards

The splitter is an important component of water-based cooling systems used to extract heat from computer boards.In the present study,the flow characteristics of a 16-splitter structure were numerically simulated and compared with experimental results to verify the reliability of the numerical simulation method.Accordingly,the concept of splitter structural coefficients was proposed.Based on the results of this study,we recommend a selection range of 5≤k≤6 for the structure factor k of the splitter;after optimization,the maximum deviation of the splitter outlet flow was reduced from the original value of 100%to 8.3%.

Numerical Simulation of Retrofit Scheme of a Boiler Tail Flue

Aiming at the problem that the total pressure loss of the flue of the electric precipitator of the 350 MW unit of a power plant to the inlet of the draft fan is too large,the numerical simulation software Fluent and the standard k-εmodel was used to simulate the flue,the results show that the main part of the flue mean total pressure loss is derived from the confluence header and elbow.In order to reduce the loss and consider the cost of transformation,the concept of twodimensional feature surface is established,gradually proposed three sets of flue transformation program and analysis of the flue transformation program drag reduction effect,the results show that the total reduction of the flue can be reduced from 486 Pa to 89 Pa and the reduction rate is 81.7%,which is the best solution;The concept of two-dimensional feature plane is helpful for quick condensing of flue;Double V-type structure of the convergence of the box has a better drag reduction effect.

Numerical Analysis of the Erosion Mechanism inside the Tube Sockets of Main Steam Thermometers in a Coal-Fired Power Plant

Leakage occurring in the tube sockets of the main steam thermometers can seriously threaten the safe operation of coal-fired power plants.Here,assuming a 300 MW unit as a relevant testbed,this problem is investigated numerically through solution of the equations of fluid-dynamics in synergy with the mathematical treatment of relevant statistics.The results indicate that the steam can form a large-scale spiral flow inside the tube socket and continuously scour the inner wall.In the model with the protective casing setting angle of 60°,the average tangential fluid velocity can reach up to 4.8 m/s,which is about twice higher than that in the model with the protective casing setting angle of 0°.The wake disturbance generated by the flow around the thermo-sensitive body leads to differences in the fluid motion inside the tube sockets between the upstream and downstream thermometers.These differences are affected by the distance between the thermometers,the setting angle of protective casing,and other factors.The pressure of the main steam inside the tube socket for a R3 thermometer,located outside the curved pipeline,is about 1756 Pa higher than that of the L3 thermometer located outside the straight pipeline,indicating that the secondary flow generated in the curved pipeline is able to provide stronger energy for the large-scale spiral flow inside the tube socket.On the basis of these findings,an improvement scheme for the installation of long-itudinal ribs in the tube sockets is proposed.The simulation results show that the average tangential velocity of the fluid within the near-wall area of tube sockets decreases by more than 90%,which should be enough to effectively alleviate the damage to the inner wall caused by high-pressure fluid or particles.

Influence of Electrical Field Distortions Induced by Water Droplets on the Contamination Characteristics of an Insulator

When separated water droplets condense on the surface of a composite insulator,the electrical field on the insulator surface is distorted.In turn,such distortions change the trajectories of pollution particles.In this study,the COMSOL software is used to simulate such a process for the FXBW4-10/100 composite insulator with or without water droplets condensation under a 10 kV DC voltage.The influence of the wind speed and particles concentration on the contamination characteristics of the considered 110 kV insulator is analyzed.The results show that:1)in the presence of water droplets on the insulator surface,the ratio of electrical field force and gravity acting on the particles is large;2)the contamination on the insulator surface increases with the wind speed;3)when the wind speed is small,the relationship between the contamination amount and the pollution concentration is essentially linear.

The Elaboration of Flow Resistance Model for a Bag Filter Serving a 200 MW Power Plant

On the basis of a macro flow resistance method and the Darcy Theory,a mathematical model is elaborated to characterize the flow resistance of a bag filter serving a coal-fired power plant.The development of the theoretical model is supported through acquisition of relevant data obtained by scanning the micro structure of the bag filter by means of an electron microscope.The influence of the running time and boiler load on the flow resistance and the impact of the flow resistance on the efficiency of the induced draft fan are analyzed by comparing the results of on-site operation tests.We show that the initial operation time and the table operation time are linearly related to the flow resistance of the bag filter;with the increase of boiler load,the flow resistance of the bag filter rises approximately as a quadratic function;with the rise of resistance,the power consumption of the induced draft fan increases while the efficiency of the induced draft fan decreases.

Numerical Simulation of Contamination Accumulation Characteristics of Composite Insulators in Salt Fog Environment

To investigate the fouling characteristics of the composite insulator surface under the salt fog environment,the FXBW-110/120-2 composite insulator was taken as the research object.Based on the field-induced charge mechanism,the multi-physical field coupling software COMSOL was used to numerically simulate the fouling characteristics,explored the calculation method of ESDD,and demonstrated its rationality.Based on this method,the pollution characteristics of the composite insulator under the pollution fog environment were studied,and the influence of wind speed,droplet size,and voltage type on the pollution characteristics of the composite insulator was analyzed.The results showed that:with the increase in wind speed,the amount of accumulated pollution of insulator increases in the range of droplet size,and the relationship between wind speed and accumulated pollution is approximately linear;at the same wind speed,the amount of accumulated pollution increases with the increase of droplet size under the action of DC voltage;when there is no voltage,the amount of dirt on the upper surface of the insulator is more than that on the lower surface,while it is the opposite under DC voltage.

Simulation of Electric Field Distribution along Insulator Surface in Polluted Environments

In recent years,more than 50%of the cities in the inland area of our country have suffered from moderate pollution.It can affect the distribution of electric field along the surface of insulator and the pollution characteristics of its surface area,even endanger the safe operation of transmission lines.This paper takes the XSP-160 porcelain three umbrella insulator under the action of 0–±30 kV DC voltage as the research object,and establishes the physical model of the insulator;uses COMSOL software to simulate the electric field of the insulator.The comparison with the results of the wind tunnel test of North China Electric Power University verifies the rationality of the simulation method.In view of the medium pollution environment which often occurs in the inland area,the force of the polluted particles deposited on the insulator under 110 kV DC voltage was analyzed.The distribution characteristics of the electric field along the surface in the clean and three kinds of pollution environment(light,medium and heavy)were simulated and compared.The results showed that:1)In the moderate pollution environment,the influence of fluid drag force on the movement of polluted particles is greater at the initial stage(0.28–0.33 s);at the late stage(after 0.33 s),the influence of the electric field force begins to increase,and gradually plays a major role in the process of fouling.2)In the three different polluted environments,the potential along the surface of each umbrella skirt of the insulator increases non-linearly with the increasing of the pollution concentration,and there are apparent potential inflection points near b and l.3)The pollution particle concentration has the most obvious influence on the electric field along the low-voltage umbrella skirt,whose potential distortion rate can be up to 220 times in the heavy polluted environment.

Research on the Flow and Heat Transfer Characteristics of a Water-Cooling Plate in a Heat Dissipation System

The water-cooling heat dissipation technology can solve the heat dissipation and noise problems of the calculation plate.Therefore,the structural design of the water-cooling plate directly affects its flow and heat transfer characteristics,which restricts the promotion and application of the technology.To this end,the water-cooling plate of a heat dissipation system was taken as the research object,and its flow and heat transfer characteristics were numerical simulated and experimental studied.Through comparative analysis,the rationality of the numerical simulation method was verified.Based on this,three improved schemes of water-cooling plate structure were proposed and numerical simulation was carried out,and the optimal model was verified by experiments.The results of the study show that compared with the original water-cooling plate,the optimized water-cooling plate has increased internal flow velocity and distributes uniformly,increased heat transfer amount by 4.2%,and the average temperature of the calculation plate decreased by 5.3%.