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Numerical Simulation of Distribution Characteristics in Centrifugal Coal Powder Distributor of Medium Speed Coal Pulverizer

Author: BaiZuo
Tutor: JinYingAi
School: Jilin University
Course: Thermal Power Engineering
Keywords: Medium speed coal pulverizer Fluent Centrifugal Coal Powder Distributor Numerical simulation
CLC: TK223.25
Type: Master's thesis
Year: 2009
Downloads: 76
Quote: 0
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Abstract


With the development of the national economy, energy issues have been placed in the primary agenda of national economic development. How the rational use of energy, energy conservation is the concept of scientific development, a major aspect. Economic development, electric power to first, the current multi-scholars are committed to exploring ways in the case of energy-saving and efficient development of power industry.Distributor of pulverized coal is coal-fired thermal power plants and other installations of the milling system, one of the key equipment, if the deviation of the distribution of coal is too large will not be able to control a single burner near the atmosphere, can not guarantee that low-NOx combustion. Therefore, in order to improve the safety of boiler operation and economy, while meeting increasingly stringent environmental requirements, we must first ensure that the burner, especially with the inter-layer burner pulverized coal and air distribution uniformity. However, the complexity of coal equipment distributor, operating power consumption, and the actual boiler with a larger size, as well as its internal temperature high mobility makes it difficult to adopt the analysis of test measurement methods for analysis, so this paper, we consider the use of CFD software for numerical simulation distributor of pulverized coal flow characteristics, to explore the speed characteristics.In recent years, accompanied by the development of computers and advances in computing technology, numerical study of the rapid development of numerical study, known as computational fluid dynamics CFD (Computational Fluid Dynamics), which uses mathematical algorithms to calculate the flow field of the control of complex differential equations to a series of discrete nodes on the grid to solve linear equations, and ultimately get the numerical solution of dispersion. Compared with the pilot study, CFD short development time, fewer requirements.Selection of this article fluent software distributor of pulverized coal separation characteristics of a variety of flow characteristics of the analysis of simulated operating conditions, the main job of work as follows:(1) Select a reasonable mathematical model, using software catia engineering drawing three-dimensional modeling, to import Gambit mesh, respectively, in the fluent movement of a single gas and gas-particle flow distributor on the performance of coal research, which for the gas flow explore the use of the k-epsilon turbulence model, selection of gas-solid flow of dispersed phase (DPM) model simulation.(2) Single distributor of pulverized coal gas flow analysis concluded that the gas flows through the distributor in all regions of the shape as a result of changes in volume distributor and had a different speed, the flow of different angles, you can clearly see that as a result of control on the coal loading and blunt separation board, opening the leaves of different shutter speeds resulting from the pressure curve. The overall flow field in a small number of high velocity region. This local area distributor body and higher quality requirements, especially the tailgate of the speed of this part of the pressure changes are significant regional, so wear and tear on the equipment more needs to pay attention to the maintenance of it.(3) Adjustable centrifugal distributor of pulverized coal in large utility boilers on the practical application, to prove the feasibility of the technology program. The distributor can be very good to improve the uneven distribution of coal pulverizer coal export situation, to ensure that different conditions in the mill, the coal powder pipe wind concentration deviation in the normal range, and ensure the normal operation of the boiler. The device can export wind mill flour mixture separated into two different concentrations and flow of air currents, so the structure can take a certain share of these two currents will carry out the redistribution, respectively, and re-convergence, re-formed the necessary flow, a mixed process of re-regulation and control, ultimately to achieve the volume of air flow and powder at the same time the purpose of uniform distribution.(4) The actual calculations show that the installation of adjustable centrifugal distributor of pulverized coal, the uniform distribution of pulverized coal concentration, increased burn-off, boiler fly ash carbon content decreased by 0.4 or so, boiler efficiency can increase to about 0.15, converted to electricity consumption fell 0.55 g / (kw ? h), effectively reduce the cost of power generation, power plants can generate considerable economic benefits. In the long run to prevent the occurrence of high temperature corrosion of heating surfaces, such as over-temperature, to extend the service life of metal furnace, boiler operation to improve security. As more stringent environmental discharge requirements, low-NOx combustion imminent tangentially burning pulverized coal boiler tube 4 uniform concentration, can effectively control the combustion air flow near the region. Precipitation in the volatile pulverized coal at the same time. New entrants continue to ignite the coal, well positioned to meet the conditions of the coal fire, to restore stability in the formation of flame ignition. So that part of NOx reduction, have excessive NOx suppression. Therefore, the coal will enable coal distributor of pulverized coal concentration tube evenly, reducing NOx emissions, reduce air pollution.

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CLC: > Industrial Technology > Energy and Power Engineering > Steam Power Engineering > Steam boiler > Boiler constructed > Combustion devices > Fuel handling equipment
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