气力输灰系统运行中存在的问题及对策

在生产实践的基础上,对气力输灰系统运行中存在的常见问题进行了论述,重点分析了输送设备上部和灰库卸灰设备的漏灰问题,以及输灰管道、仓泵设备和阀门的磨损问题、并提出了相应的对策。     

火电机组省煤器灰输送中存在的问题及对策

火电机组省煤器单元输灰系统运行成本高、易堵管、输灰管道磨损严重等问题。分析了产生的原因,提出了优化方案,并通过对比优化前后的输灰系统的使用情况,结果表明,优化后的正压浓相气力输灰系统是一种能有效降低运行成本、减少系统维护量的方法。     

气力输灰系统设计、选型和运行的建议

文章探讨火电厂气力输灰系统在设计、选型和运行维护中存在的一些问题,并提出相关避免及解决问题的建议。     

浅谈输灰系统节能运行

阜阳华润电力有限公司自2012年起，开始对电除尘输灰系统节能潜力进行挖掘，通过运行方式的不断探索和优化，将输灰空压机运行台数由原来的5台降低至3台运行，降低了输灰系统空压机厂用电率及设备维护费用，取得了良好的节能效果。     

STT焊接技术的研究

随着我国长输管道工程的发展,长输管道管径越来越大和管道钢管强度也不断增加,针对大口径和高强钢的焊接研制了STT根焊技术在输管道中应用较为广泛,本文详尽介绍了林肯STT设备参数及调节、长输管道工程STT根焊焊接工艺及操作技术要点。     

多泵制正压浓相气力输灰系统的性能及其在天生港发电厂的应用

目前国内正压浓相气力输灰系统具有低能耗、耐磨损及系统简单等优点,但单泵制运行方式又制约了其在多灰斗、大机组电厂的使用。本文介绍了天生港发电厂多泵制正压浓相气力输灰系统,该系统配置相对简单、可靠,适合多灰斗、大机组电厂的除灰系统。     

电厂水力输灰管道声波除垢技术的研究

燃煤电厂广泛使用水力输灰系统输送粉煤灰，水力输灰管道结垢是影响该系统安全经济可靠运行的主要问题。目前已有的灰管除垢方法，如管壁涂料防垢法、加酸法、炉烟处理法、ＰＨ值闭路循环法、干湿式除尘灰水混排法等，普遍存在着运行费用高，有二次污染的缺点，难以在实际工作中推广使用。灰管声波除垢是新近发展起来的一种物理清除方法，它利用动力式发声器把高速射流转换成大功率声波，送入水力输灰管道中，通过声波的作用去除管内的灰垢。该方法可在除灰系统正常运行的情况下进行，运行费用低，对设备无腐蚀，是保证输灰系统安全经济运行…     

基于S7-300PLC在发电厂输灰系统中的应用研究

PLC西门子S7-300可编程序控制器的采用,为发电厂企业提供了一个更简便、灵活、经济适用的输灰系统的工艺流程。发电厂为实现自动化输灰方式,正确发挥PLC可编程序控制器在输灰系统中的作用,能使发电厂赢取更多的利益。本文主要分析了PLC系统的优势,在实际操作中的实现方式以及评标标准。     

爆炸载荷作用下输灰管力学效应与灰垢清除

在弹塑性力学和爆炸力学的基础上，对爆炸载荷作用下输灰管的力学效应进行了理论分析，探讨了灰垢的破坏机理，为进一步研究输灰管爆破除垢提供了一定的理论依据。     

浅谈圆顶阀的工作原理及使用

在现代的电力生产中，气力输灰系统越来越多的被采用。在气力输灰系统中圆顶阀是一种气体输送固体物料系统中常用的物料开关器，起到开通和隔断管道空间的作用。它被用于通过松散的、干燥的、非粘性的、可流动的固体物料的密封输送系统。但是，如果圆顶阀的安装、调试和使用等环节任何一个环节出现问题，都会严重影响圆顶阀的安全、可靠及经济运行，最终导致输灰系统停运。     

射流管在气力输送中的应用

对物料气力输送的各种供料方式的性能、特点和使用场合进行了比较 ,重点讨论了传统文丘里供料器实际应用中存在的问题 ,介绍了几种国内外新型的文丘里供料器结构及其特点和用途。指出采用组合式供料器 ,即将文丘里供料器与机械旋转式连续供料器进行组合使用 ,可以同时改善它们两者单独使用时存在的问题。文中介绍了LAVAL管密相输送气量控制方面的应用 ,指出LAVAL管在气力输送中主要起稳定空气流量和压力的作用 ,使输送过程稳定、均匀 ,并简要介绍了气力输送系统的设计方法和步骤     

低速高能效的浓相气力输送技术

低速浓相输送装置的出现,解决了物料在输送过程中易破碎、堵塞和磨蚀管道等难题,降低了耗气量。本文中综述了低速浓相输送的几种定义和输送过程中的相图、物料流动形态及相应的判定、影响浓相气力输送特性的因素等技术参数,并介绍了输送过程中经常遇到的堵管和磨损现象以及气力输送过程中的检测和自动控制技术,指出了今后的研究方向。     

粉体性能对浓相气力输送特性的影响

气力输送过程中物料性能是确定输送特性的重要因素,因此,粉料气力输送技术的实现要以对粉料的性能研究为基础。文中对影响气力输送的粉体基本性能及其相关参数做了较全面分析,其中粒子尺寸、粒径分布、形状是影响粉料是否可适用于浓相气力输送的关键参数,其它特性都与这3种特性相关联。介绍了几种应用广泛的粉料气力输送特性分组方法,并进行了简要评述,同时指出了今后的研究方向。     

正压浓相恒压输送系统的DCS控制设计及应用

正压浓相气力输送系统是目前国内火电厂应用最为广泛的气力输送系统,该系统对运行的控制流程要求高、逻辑性强;其关键输送技术指标均采用模拟量进行检测,并实时控制.本文介绍的恒压输送系统,除了以上特点外,其独具的输送压力的动态实时调控功能,更是对控制系统提出更高的要求;阐述了DCS用于正压浓相恒压输送系统的典型设计.     

Monitoring of scaling in dilute phase pneumatic conveying systems using non-intrusive acoustic sensors – A feasibility study

Scale formation in pneumatic conveying systems is a major industrial challenge. The underlying scale formation mechanisms can be intricate as they often involve a combination of several mutually enhancing binding forces and can be affected by a number of different factors. A non-intrusive monitoring technique capable of measuring scale growth would be a valuable tool to investigate different scaling mechanisms. In this study, the feasibility of an active acoustic sensor technique for monitoring of scale growth in a pneumatic conveying system is evaluated. Tests are performed in a pilot scale pneumatic conveying system transporting sand in dilute phase. The acoustic sensors conducts measurements on test pipes which are coated with a primer/powder mixture, one layer after the other, to simulate scale progression. Reference measurements of the coating layer thickness in the test pipes are obtained by a laser imaging technique for each added coating layer. A multivariate method is used to calibrate prediction models of the scale thickness using acoustic measurements as independent variables and the reference measurements as the dependent variable. Results show that the active monitoring method is capable of monitoring scale growth in pneumatic conveying systems and that dilute phase conveying of sand does not affect the precision of predictions made by the method.     

An investigation of segregation and mixing in dense phase pneumatic conveying

Pneumatic conveying of bulk materials has become an important technology in many industries: from pharmaceuticals to petro-chemicals and power generation. Particulate segregation has been investigated in many solids handling processes. However, little work has been published on the segregation and mixing in pneumatic conveying pipelines, particularly in dense phase pneumatic conveying. Due to the character of dense phase flow, it is difficult to investigate the segregation in a flowing plug. A sampling device was designed and built to take samples from the pneumatic conveying pipeline after “catching a plug”. Several experiments were conducted over a range of gas–solids flow conditions with 3 mm nylon pellets and 3 mm ballotini as a segregating mixture. Experimental data combined with video footage were analysed to describe the segregation and mixing of solids plugs in pipes. This investigation provides initial research on establishing a segregation index in a flowing plug. A gas–solids two-dimensional mathematical model was developed for plug flow of a nylon-glass particulate mixture in a horizontal pipeline in dense phase pneumatic conveying. The model was developed based on the discrete element method (DEM). The model was used to simulate the motion of particles both in a homogeneous flow and as binary mixtures taking into account the various interactions between gas, particles and pipe wall. For the gas phase, the Navier Stokes equations were integrated by the semi-implicit method for pressure-linked equations (SIMPLE) using the scheme of Patankar employing the staggered grid system. For the particle motion the Newtonian equations of motion of individual particles were integrated, where repulsive and damping forces for particle collision, the gravity force, and the drag force were taken into account. For particle contact, a model with a simple non-linear spring and dash pot model for both normal and tangential components was used. This model employed a mixture of 3 mm pellets and ballotini as virtual materials with properties of nylon and glass. The results from the model are discussed and compared with experimental work and show qualitative agreement. Further modelling and experimental work in key areas is proposed.     

密相气力输送系统中几种气量控制方式的比较

从调压范围、压力特性和流量特性方面介绍了减压阀的主要性能,讨论了气力输送交流中减压阀的选择和调节,分析了密相气力输送系统中各种气量控制方法,对其各自的优缺点进行了详细讨论,重点分析减压阀及减压阀与拉法尔联合气量控制系统的优、缺点,表明可调式拉法尔管是今后气力输送气量控制发展的方向。     

An Experimental Technique for the Analysis of Slug Flows in Pneumatic Pipelines Using Pressure Measurements

An experimental technique has been developed to measure the flow characteristics of slugs in dense phase pneumatic conveying using pressure measurements. This method is based on the unique characteristics of slug flows in pipes, i.e., an axial pressure fluctuation along the pipeline and a pressure difference in the radial direction at the back of a slug. Standard differential pressure transducers were used in this study and the influence of the finite response time of these transducers was considered. Experiments were conducted over a range of gas-solids flow conditions and experimental data were analyzed to describe the behavior of solids slugs through pipes. The calculated slug velocity and length using axial pressure measurements were confirmed by video recordings, and the synthesis between axial and radial pressure signals showed reasonable agreement in flow pattern analysis. This relatively simple measuring technique has been found effective in detecting solids slugs traveling through horizontal pipes and will distinguish various flow regimes. It provides a useful and easily applied tool for system optimizing and benchmarking in industrial applications.     

An Experimental Technique for the Analysis of Slug Flows in Pneumatic Pipelines Using Pressure Measurements

An experimental technique has been developed to measure the flow characteristics of slugs in dense phase pneumatic conveying using pressure measurements. This method is based on the unique characteristics of slug flows in pipes, i.e., an axial pressure fluctuation along the pipeline and a pressure difference in the radial direction at the back of a slug. Standard differential pressure transducers were used in this study and the influence of the finite response time of these transducers was considered. Experiments were conducted over a range of gas-solids flow conditions and experimental data were analyzed to describe the behavior of solids slugs through pipes. The calculated slug velocity and length using axial pressure measurements were confirmed by video recordings, and the synthesis between axial and radial pressure signals showed reasonable agreement in flow pattern analysis. This relatively simple measuring technique has been found effective in detecting solids slugs traveling through horizontal pipes and will distinguish various flow regimes. It provides a useful and easily applied tool for system optimizing and benchmarking in industrial applications.     

Minimum Transport for Dense-Phase Conveying of Granules

The minimum transport or capacity limitation boundary for low-velocity slug-flow pneumatic conveying affects the design and operation of conveying systems. Unfortunately, the relevant mechanisms involved with this boundary still lack full understanding and assessment. Investigations have been carried out to model the capacity limitation for the low-velocity slug-flow pneumatic conveying of poly granules through horizontal pipes. Pipeline diameter, air mass flow rate, and operating pressure have been found to affect the maximum slugging capacity of this material. A semiempirical equation has been established to predict the maximum solids mass flow rate for a given air mass flow rate and conveying pipeline. Good agreement has been achieved between the model predictions and the experimental results over a wide range of airflows and pressures.