循环流化床锅炉布风板漏渣与稳定性

深入研究了某热电厂450t/h循环流化床锅炉运行中炉膛布风板严重漏渣的问题,根据布风板稳定运行的基本原理以及锅炉结构和实际运行数据,对炉膛布风板的漏渣原因进行了理论分析,计算了布风板当量直径与床层高度的比值对流化床临界压降的影响,合理地解释了漏渣的机理,并讨论了可能存在的炉膛布风板设计和运行上的原因。图7参2     

循环流化床锅炉改变床存量的燃烧试验

在1台75 t/h循环流化床锅炉上进行了改变床存量的燃烧试验,在3220～7330 Pa床层压降变化范围内,测试了改变床存量对锅炉负荷能力、炉内轴向颗粒浓度分布以及实际燃烧效率的影响.结果表明:在远低于常规床层压降的条件下,循环流化床锅炉仍能保持满负荷运行,而且燃烧得到改善;在适当控制燃料粒度的条件下,循环流化床锅炉降低床层压降运行不仅可行,还可以使锅炉整体运行性能得到优化,是锅炉设计和运行优化的方向.     

双级料腿循环流化床压力平衡分布的研究

该文在双级料腿循环流化床冷态实验装置中测定了不同工况下的压力平衡分布，详细分析了各种运行工况对压力平衡分布的影响。实验结果表明：双级料腿循环流化床压力平衡主要依靠第二级循环料腿中物料的停留量来维持。调节压力平衡的关键是第二级循环料腿中脱氯床(包括布风板和床层)的阻力。通过压力平衡计算得到了脱氯床阻力的计算公式。     

循环流化床锅炉布风板阻力与料层阻力特性的冷态试验研究

在商业运行的循环流化床电站锅炉中,布风板阻力和料层阻力是炉内重要的测量参数,其中布风板阻力试验和料层阻力试验是流化床锅炉冷态试验的重要组成部分。对于布风板阻力与料层阻力的关系,已有文献仅仅阐明在鼓泡流化状态中,两者存在合理的相关值,但是在快速流化状态中,两者的关系尚未得到广泛研究。利用循环流化床锅炉冷态试验台,开展了在不同物料容量、物料直径等运行参数条件下,布风板阻力与料层阻力关系的试验研究,并取若干具有代表性实炉统计出压力比情况,相关结论对现场实炉生产运行具有很高的参考价值。     

物料量及布风板阻力对裤衩腿流化床锅炉翻床的影响

基于颗粒动力学两相流方法,建立了裤衩腿循环流化床锅炉二维CFD数值计算模型,研究了总物料量和布风板阻力特性对翻床趋势的影响.结果表明:炉膛总物料量越大,平均物料交换率越大,越容易翻床;布风板阻力系数越大,平均物料交换率越小,越不容易翻床;正负反馈机理可以合理解释物料量和布风板阻力特性对翻床的影响;布风板压降和物料压降比是评价裤衩腿循环流化床锅炉自平衡能力的重要参数.     

流化床锅炉燃用烟煤风帽磨损的问题分析

介绍了循环流化床锅炉改烧烟煤的时候布风板风帽的一些问题以及相关的分析,介绍了运行调整的方法和解决措施。     

CFB锅炉风帽改造及试验研究

钟罩式风帽存在的问题与现场安装、运行控制和日常检修息息相关,文中针对某厂循环流化床锅炉钟罩式风帽存在的问题进行分析研究,改造应用新型耐磨防漏渣风帽,完成了布风板阻力试验和料层阻力试验.结果显示,改造后风室漏渣和流化不均彻底消除,改造取得了圆满成功,相关研究可为今后循环流化床锅炉同类改造参考.     

600MW超临界循环流化床锅炉水冷壁热应力分析

为研究超临界循环流化床锅炉水冷壁的变形问题,在实炉测量某600 MW超临界循环流化床锅炉炉膛水冷壁壁温分布的基础上,采用数值模拟方法对距离布风板30m高度处4.6m×2m区域的水冷壁管进行了热应力分析。结果表明:80%负荷工况下,距离布风板30m高度处区域的水冷壁管沿炉膛高度方向的温度变化率较大,热应力分布极不均匀;计算区域的水冷壁管整体向下膨胀,由于存在膨胀偏差,水冷壁向火侧向炉内凸起变形,最大变形量约1.14mm;对于整个水冷壁管屏而言,存在的变形量叠加会加剧水冷壁磨损,甚至造成爆管事故。     

150 MW CFB锅炉燃烧均匀性优化及实践

某电厂150 MW循环流化床(CFB)锅炉运行过程中存在床温偏高,床温均匀性较差,直接导致锅炉NOx原始排放量高,脱硫脱硝单耗偏高,屏式过热器壁温偏差较大等问题.在与锅炉厂研讨分析后得出煤质变化、布风不均及二次风分级燃烧效果不佳是主要原因.为此在电厂锅炉上实施布风板风帽分区及二次风深度分级等改造.改造项目实施后,锅炉运...     

循环流化床锅炉燃烧室边界层的实验研究

循环流化床锅炉燃烧室的物料浓度影响传热和燃烧,在75t/h循环流化床锅炉上对燃烧室物料浓度分布的测量结果发现,循环流化床锅炉燃烧室的下降流边界层中在接近壁面处存在气体边界层,气体边界层的厚度与距离布风板高度有关,据此给出了下降流边界层厚度和气体边界层厚度的计算公式,并提出了循环流化床燃烧室双环模型。     

新型加压填料饱和器及其关键结构研究

为了进一步揭示HAT循环的集成和运行的规律,促进HAT循环的商业化,搭建了100kW级的HAT循环示范系统。本文主要工作是研制HAT循环的关键部件加压饱和器及其内部气体分布器、液体分布器、气液两相测量装置等。在前人工作基础上,设计了分布性能好、压力损失小的双向环流式气体分布器。利用FLU-ENT软件对其进行了数值分析,结果显示该气体分布器可以满足饱和器内气流分布均匀性的要求。     

Numerical Investigation on the Two Phase Flow Behaviors in Supercritical Water Fluidized Bed with Swirling Flow Distributor

ABSTRACT

Supercritical water fluidized bed reactor is a promising in the clean and efficient conversion of coal, and the distributor is one of the key component for the heat and mass transfer enhancement. However, the optimization study for the distributor in supercritical water fluidized bed reactor has been seldom conducted due to the special thermal properties of supercritical water. In this work, the swirling flow distributor was designed for its optimization for heat and mass transfer inside a supercritical water fluidized bed reactor. The swirling flow can be generated by the concentric circle or triangle type hole distribution in distributor with 0 or 45° intersection angle between the fluid inlet velocity direction and the distributor plane. The computational particle fluid dynamics (SCWFB) method, which has quick calculating speed and high accuracy, was used in this work to study the particle-fluid two-phase flow behaviors inside SCWFB with swirling flow distributors. Investigations were made to reveal the influence of the hole distribution type and intersection angle on the bed pressure drop and particle volume fraction characteristics. The results showed that the triangle type distributor with 45° intersection angle has the best fluidization performance. The conclusions drawn may has potential application for continuous and stable operation of supercritical water fluidized bed reactor for coal gasification.     

生物膜滴滤塔液体分布器实验研究

以有机废气处理生物膜滴滤塔为背景，分别设计了盘式和槽式两种液体分布器，通过实验研究了液体喷淋密度、喷淋区域等对液体分布器分布性能的影响，并对两种分布器的液体分配特性进行了比较，盘式液体分布器的液体分配性能总体上优于槽式液体分布器。随后针对盘式液体研究了安装水平度、进液方式对液体分布性能的影响。     

自动可调叶栅煤粉分配器的应用研究

介绍了一种新型自动可调式煤粉分配装置,重点说明了它的稳燃原理及其在风扇磨煤机直吹式制粉系统中的应用情况。通过大量的工业试验,对自动可调式煤粉分配器的风量,煤粉量的调整特性进行了研究。结果表明;新型自动可调叶栅煤粉分配器应用于国产670t/h褐煤锅炉中,能在运行中对空气和煤粉分配进行调节,实现了风粉分配由不可控制到有效控制,使锅炉的低负荷不投油稳燃能力由原来70%降低到45%。达到了大幅度降负荷运行的目的,并且由于燃料在炉内燃烧被分为过浓燃烧和过淡燃烧两部分,使NOx排放量低于469mg/m^3,机械不完全燃烧损失降低了1.958%。有效地提高了锅炉机组的热效率和低负荷运行的能力。图9表3参2     

基于PIC单片机的步进电机控制系统

采用PIC系列单片机作为步进电机控制系统的核心,实现了软件与硬件相结合的控制方法。用软件代替脉冲分配器,达到了对步进电机的最佳控制。采用单极性驱动电路对小功率步进电机进行驱动,电路简单,实用性好。用LCD显示屏对步进电机的预设工作状态进行动态显示,直观、明了。实验结果表明整个控制系统成本低,精度高,运行平稳,可靠性好。     

Two/three-dimensional reduced graphene oxide coating for porous flow distributor in polymer electrolyte membrane fuel cell

There are drawbacks to use stainless-steel plates as a flow distributor plate in fuel cell, due to some of their properties being inferior to graphite flow distributor plates in terms of electrical conductivity and corrosion resistance. To overcome these problems, many researches have been conducted to improve the properties of stainless-steel flow distributor plates through coating of carbon materials. Herein, two-dimensional Web-like graphene (WG) and self-assembled three-dimensional graphene (STG) are coated through superheat vaporization of micro-droplet method. WG is coated in porous Ni–Cr foam and STG is constructed on the flat flow distributor plate, and they exhibit the feasibility to be applied in flow distributors. Compared to uncoated Ni–Cr foam, the performance of the PEMFC system with the graphene coated foam is enhanced remarkably. Furthermore, the flow distributor plate with the STG exhibits potential to be used directly to flow distributor.     

格栅型煤粉分配器的分配特性研究

为了研究格栅型煤粉分配器的均匀分配效果,在分配器入口前加设一段弯管以形成分配器入口气固两相流动的非均匀条件,利用Fluent软件对不同格栅数的煤粉分配器的性能进行数值模拟,得到其内部流动情况以及颗粒运动状态.结果表明:在两级格栅出口转角处磨损严重,在流通截面扩大处磨损较小;每根支管的出口速度都不均匀.随着格栅数增加,各...     

关于循环流化床锅炉冷态空气动力场试验的研究

以某480 t/h循环流化床锅炉的空气动力场试验为例,详细介绍循环流化床锅炉空气动力场试验目的、试验项目和试验方法,并得出结论和建议。通过测定循环流化床锅炉锅炉布风板阻力特性和流化特性,得出锅炉的临界流化风量,为锅炉的热态运行提供必要的依据,保证循环流化床锅炉的安全、经济运行。     

Comparison of temperature distributions inside a PEM fuel cell with parallel and interdigitated gas distributors

A comparison of the temperature distributions in a proton exchange membrane (PEM) fuel cell between the parallel-flow gas distributors and the interdigitated gas distributor has been discussed in detail. An electrochemical–thermal coupled numerical model in a five-layer membrane-electrode assembly (MEA) is developed. The temperatures for the reactant fuels as well as the carbon fibers in the porous electrode are predicted by using a CFD technique. The overpotential across the MEA is varied to examine its effect on the temperature distributions of the PEM fuel cell. It is found that both the fuel temperature and the carbon fiber temperature are increased with increasing the total overpotential. In addition, the fuel and carbon-fiber temperature distributions are significantly affected by the flow pattern that cast on the gas distributor. Replacing the parallel-flow gas distributor by the interdigitated gas distributor will increase the local maximum temperature inside the PEM fuel cell.