除尘器灰斗堵灰的原因分析及解决对策

除尘器灰斗堵灰严重影响除尘器的安全运行,通过调查对除尘器灰斗堵灰的原因进行分析及归类,得出除尘器灰量增大或灰的粒径变粗造成输灰系统输送异常是除尘器灰斗堵灰的最主要原因,并提出解决对策。     

滤筒除尘器及应用现状

滤筒除尘器比袋式除尘器具有明显的优势.综述了滤筒除尘器的性能和特点,根据国内外文献报道,介绍了滤筒除尘器在工业中的应用,分析了目前存在的一些问题和解决方式,指出了滤筒除尘器主要的研究内容是新型滤料和相适应的喷吹系统.     

大扩张角电袋复合除尘器内多孔板组合方案试验研究

为了改善大扩张角电袋复合除尘器入口流场速度分布,提高除尘器效率,采用不同开孔率多孔板的组合方案,对电袋复合除尘器进行了模拟试验。结果表明:入口截面相对速度偏差由84%降至21%,除尘器内各测量截面速度分布均达到标准要求;可以采用非均匀开孔率的多孔板组合方案来调节电厂电袋复合除尘器内部流场速度分布,从而增加电袋复合除尘器使用寿命,降低电袋复合除尘器维修成本,提高电袋复合除尘器效率。     

滤筒除尘器及应用现状

滤筒除尘器比袋式除尘器具有明显的优势。综述了滤筒除尘器的性能和特点,根据国内外文献报道,介绍了滤筒除尘器在工业中的应用,分析了目前存在的一些问题和解决方式,指出了滤筒除尘器主要的研究内容是新型滤料和相适应的喷吹系统。     

220t／h煤粉炉水膜除尘改为静电除尘效能分析

1　除尘器技改的必要性南京第二热电厂三台 2 2 0 t/h煤粉锅炉配有六台水膜式 (麻石 )除尘器 ,这六台除尘器最长的已使用了近十年 ,设备趋向老化 ,并且这种水膜除尘被淘汰。为了进一步减少市区北郊燕子矶工业区的环境污染 ,保护南京经济技术开发区的投资环境 ,根据省、市环保加快实施南京第二热电厂锅炉除尘器的改造工作的指示精神 ,这次 1 #炉除尘器改造就是将现有的水膜式除尘器改造成为静电除尘器。南京第二热电厂一期工程建设时 ,原设计中的锅炉静电除尘器由于当时资金困难 ,改为目前使用的价格较低的水膜式除尘器。从近十年的使用情况…     

颗粒层除尘器过滤和清灰方式的优化

分析了移动床颗粒层除尘器存在颗粒层间隙增大和颗粒错位等影响除尘性能的问题,并优化出能克服这些问题的新型结构和过滤方式的颗粒层除尘器;介绍了新型颗粒层除尘器的结构和特点,特别是组合流化床清灰机构能实现颗粒层的快速清灰;建立了除尘器床层压降的数学模型,通过实验摸索出颗粒层流化清灰规律和除尘器的过滤性能。理论和实践表明,新型颗粒层除尘器的除尘性能优于其它颗粒层除尘器,能实现了除尘和清灰一体化,清灰过程更简便。     

电极形式和布置方式对静电旋风除尘器性能的影响

静电旋风除尘器是在旋风除尘器内加入电极以引入高压静电场,实现离心除尘机理和静电除尘机理相结合的多机理除尘设备。静电除尘机理如何与离心除尘机理有机地结合从而发挥各自的优势,是静电旋风除尘器值得研究的主要问题,也是国内外学者研究的重点之一。静电旋风除尘器内的电极布置和单纯的管式静电除尘器和板式静电除尘器的电极布置差别很大。电极的形式和布置方式不仅关系到静电旋风除尘器能否很好地发挥电场力和离心力的综合作用,而且对电极的安装、电源的要求也是非常重要的。通过大量的实验,研究了静电旋风除尘器的电极形式和布置方式对除尘器性能的影响。     

袋式除尘器的除尘机理和影响因素

与电除尘器相比,袋式除尘器的除尘率在99.96%以上,运行稳定,可以对较小的重金属和粉尘进行捕捉,具有不错的环保和节能效果。叙述了袋式除尘器的工作原理和袋式除尘器清灰的机理,分析了对袋式除尘器造成影响的主要因素。     

电袋复合式除尘器的应用与管理研究

随着我国科学技术的不断发展,为适应工业规模的扩大化,工业除尘器从一开始的电除尘器,袋式除尘器,应运而生了电袋复合式除尘器,使我国工业的除尘技术越来越标准。本文主要对电袋复合式除尘器的管理和应用进行分析研究。     

电袋复合除尘器性能试验

利用试验台进行电袋复合除尘器的冷模试验,可以系统地研究不同参数变化时除尘器性能的变化规律,从而可预测工程装置运行时的效果。介绍了厦门嵩屿电厂当除尘器含尘浓度、烟气量变化时除尘器性能的变化规律。     

Studies on a two-staged micro-combustor for a micro-reformer integrated with a micro-evaporator

A new micro-combustor configuration for a micro fuel-cell reformer integrated with a micro-evaporator is studied experimentally and computationally. The micro-combustor as a heat source is designed for a 10–15 W micro-reformer using the steam reforming method. In order to satisfy the primary requirements for designing a micro-combustor integrated with a micro-evaporator, i.e., stable burning in a small confinement and maximum heat transfer through a wall, the present micro-combustor is a simply cylinder, which is easy to fabricate, but is two-staged (expanding downstream) to control ignition and stable burning. The aspect ratio and wall thickness of the micro-combustor substantially affect ignition and thermal characteristics. For optimized design conditions, a pre-mixed micro-flame is easily ignited in the expanded second-stage combustor, moves into the smaller first-stage combustor, and finally is stabilized therein. The measured and predicted temperature distributions across the micro-combustor walls indicate that heat generated in the micro-combustor is well transferred. Thus, the present micro-combustor configuration can be applied to practical micro-reformers integrated with a micro-evaporator for use with fuel cells.     

Matching of a DC motor to a photovoltaic generator using a step-upconverter with a current-locked loop

A photovoltaic (PV) generator is a nonlinear device having insolation-dependent volt-ampere characteristics. Because of its relatively high cost, the system designer is interested in optimum matching of the motor and its mechanical load to the PV generator so that maximum power is obtained during the entire operating period. However, since the maximum-power point varies with solar insolation, it is difficult to achieve an optimum matching that is valid for all insolation levels. In this paper it is shown that for maximum power, the generator current must be directly proportional to insolation. This remarkable property is utilized to achieve insolation-independent optimum matching. A shunt DC motor driving a centrifugal water pump is supplied from a PV generator via a step-up converter whose duty ratio is controlled using a current-locked feedback loop     

Coupling a two-temperature model and a one-temperature model at a fluid-porous interface

We study a convective heat transfer problem in a fluid-porous domain in the case of the local thermal non-equilibrium assumption (LTNE). The issue of this study is to determine appropriate boundary conditions to model heat transfer, while using models with a different number of equations: a two-temperature model in the homogeneous porous region versus a one-temperature model in the free region. To proceed, a two-step up-scaling approach is used, which has the particularity to provide closed jump relations depending on intrinsic characteristic of the interface. Thus, the use of jump or continuity conditions depend only on the interface location inside the fluid-porous transition region. The pertinence of the approach is illustrated on a 2D convective heat transfer problem considering a solid heat source in the porous medium.     

Natural convection of a non-Newtonian fluid about a horizontal cylinder and a sphere in a porous medium

The problem of natural convection of a non-Newtonian fluid about a horizontal isothermal cylinder and an isothermal sphere in the porous medium is considered. The present study is based on the boundary layer approximation and only suitable for a high Rayleigh number. Similarity solutions are obtained by using the fourth order Runge-Kutta method. The effects of the wall temperature T_W and the new power-law index n on the characteristics of heat transfer are discussed.     

From a scholar city to a solar city

Located on “Bartolomé Masó” municipality on the north part of “Sierra Maestra” in “Granma” province, the Scholar City “Camilo Cienfuegos”, represents a paradigm of the real ideals of the Cuban Revolution related to education. The paper presents the results of a work developed by a team of professors and students of the Faculty of Architecture and Mechanic Engineering in the Polytechnic University of Havana (ISPJAE) in 1997, which includes a diagnosis of its current situation as a consequence of its historical development, and an strategy for its transformation into a sustainable city.The proposed strategy deals with economic and social sustainability, preservation of natural resources, energy conservation, and appropriate technology, considered in 3 main concepts: Habitat city, Cultural city, and Sustainable city, which are finally integrated into a Solar City as a symbolic term. As part of the proposal, a Master Plan, urban and architectural design criteria and steps for the future development are presented.     

Thermal Green's Functions for a Heat Source in a Piezoelectric Solid with a Parabolic Boundary

Using the Stroh formalism combined with the analytical continuation principle of Muskhelishvili, the Green's functions for a line heat source in a piezoelectric solid with a parabolic boundary are obtained in closed form. The obtained Green's functions not only satisfy all the given boundary conditions, but also ensure the displacement and electric potential to be single-valued. As special cases, the solutions for a piezoelectric half-plane are also presented, and they are shown to be consistent with previous works.     

Heat Transfer to a Particle Exposed to a Rarefied Plasma with a Great Temperature Gradient

A kinetic-theory analysis is presented concerning the heat transfer from a rarefied plasma to a spherical particle for the extreme case of free-molecule regime and thin plasma sheath. A great temperature gradient is assumed to exist in the plasma, and thus a non-Maxwellian velocity distribution function is employed for each of the gas species. Analytical results show that the existence of a temperature gradient in the plasma causes a nonuniform distribution of the local heat flux density on the sphere surface, while the total heat flux to the whole particle is independent of the temperature gradient. The nonuniformity of the local heat flux distributioln is small even for the case with a temperature gradient as great as 10~6 K/m, but it may significantly enhance the thermophoretic force on an evaporating particle. Heat transfer is mainly caused by atoms at low gas temperatures with negligible ionization degree, while it can be attributed to ions and electrons at high plasma temperatures.     

Solidification of a liquid about a cylindrical pipe

The temperature distribution and the rate of removal of heat by a coolant are predicted for the process of solidification of a liquid about a cold, isothermal pipe. The heat balance integral method incorporating spacial sub-division is used. It is found that acceptable results can be obtained by using only a small number of sub-divisions together with a piece-wise, linear profile. Furthermore, the results illustrate that the sensitivity which is normally associated with the heat balance integral method is overcome.     

Turbulent mixed convection of a nanofluid in a horizontal curved tube using a two-phase approach

Turbulent mixed convection heat transfer of a nanofluid consisting of water and Al₂O₃ (d_p = 28 nm) throughout a horizontal curved tube has been investigated numerically. Two-phase mixture model has been implemented to study such a flow field. Elliptical governing equations have been solved to investigate the flow behaviors. Simultaneous effects of the buoyancy force, centrifugal force, and nanoparticles concentration have been presented and discussed. The computed results are compared with previously published experimental and numerical data for a base fluid (very low volume fraction, Φ ≈ 0, in the present simulation) and good agreement between the results is observed. It is seen that the nanoparticle volume fraction does not have a direct effect on the secondary flow and the skin friction coefficient. However its effects on the thermal parameters and flow turbulent intensity are significant.