适用于燃用贫煤1 025 t/h锅炉的中心给粉旋流燃烧器

提出了中心给粉旋流煤粉燃烧器,并针对某厂采用EI-DRB型燃烧器设计燃用贫煤的1 025 t/h锅炉稳燃能力差,不能燃用设计煤质的问题,进行了实验室冷态试验及锅炉冷、热态试验,得出了新型的燃烧器结构,并将下层8只燃烧器改造为新型燃烧器.试验表明,中心给粉燃烧器的回流区最大直径、长度与燃烧器最外层直径之比分别为1.40和1.89,可卷吸足够的高温烟气及时点燃煤粉,得出了外二次风叶片角度、一次风量、二次风量及三次风对燃烧器出口射流的影响规律;在实际运行参数下,EI-DRB型燃烧器没有回流区,不利于稳定燃烧.得出了二次风挡板开度和给粉机转数对燃烧器出口处温度场的影响规律.采用新型燃烧器后,锅炉效率提高,当电负荷降至140 MW时,锅炉可以不投油稳定运行,在燃用贫煤、无烟煤和贫煤的混煤时(混合比为11),锅炉在高负荷和低负荷下均可稳定运行.锅炉NOx排放下降.     

空气分级炉膛煤粉燃烬模型及实炉试验对比

传统的炉膛分区段传热设计模型忽略了煤粉燃烬计算,适用于非空气分级燃烧。随着空气分级低NOx燃烧技术的普遍应用,在炉膛分区段传热计算中引入煤粉燃烧模型以确定沿炉膛高度燃烬分布,对于提高炉膛上部屏式或辐射受热面蒸汽温度设计准确性有较为重要的意义。建立了改进型分区段传热计算和煤粉燃烧相耦合的空气分级炉膛燃烬和传热模型,对一台空气分级低NOx燃烧锅炉进行了全负荷工况试验,采用该模型对试验工况进行燃烬和传热模拟,得到空气分级锅炉炉膛煤粉燃烧过程的物理图景以及煤粉沿炉膛高度燃尽分布,并研究了燃烧模式和表面反应动力学参数等对燃烬度分布的影响。结果表明,炉膛出口煤粉颗粒燃烬度数值解与大部分测试数据吻合较好,煤粉颗粒燃烧后期灰分引起热退火抑制效应以及炉内局部烟气含氧量分布不均匀是引起模型误差的主要因素,所建立的燃烧和传热耦合模型与传统的炉膛分区段传热模型计算量相当,适合工程应用。     

中心给粉旋流燃烧器气固两相流动的数值模拟

电厂采用的煤粉燃烧技术应达到稳燃、低污染、防结渣及防高温腐蚀的要求。中国电厂燃用煤的煤质偏差,煤种多变。在燃用这些煤的时候,锅炉的稳燃能力较低。针对这些问题,提出中心给粉旋流煤粉燃烧技术。由于燃烧器的气固流动特性对燃烧器的性能有很大的影响,利用可实现的k-ε和Lagrangian随机轨道模型对中心给粉旋流燃烧器的气固两相流动进行数值模拟,并将计算结果和三维相位多普勒测速技术(Phase-Doppler anemometry,PDA)试验结果进行详细比较,计算值和试验值速度分布的趋势基本相同。计算和试验结果表明,在轴向方向产生了回流区,切向速度分布出现典型的Rankine涡结构,中心线附近区域的径向速度小。当颗粒的轴向速度衰减为0之后,颗粒的运动方向发生偏转,开始向后上方运动。颗粒迂回型运动轨迹延长了煤粉在回流区中的停留时间。     

1000MW超超临界燃煤锅炉燃烧与NO_x排放特性试验研究

为实现高效燃烧和低NOx排放,在一台1000MW对冲燃烧烟煤锅炉上进行燃烧优化调整试验,测量炉膛烟气温度分布,研究煤种、省煤器出口氧量、燃尽风量、燃烧器及燃尽风风门开度、燃烧器投运方式和负荷等因素对燃烧和NOx排放的影响规律。试验表明,省煤器出口氧量和燃尽风量对锅炉效率和NOx排放有较大影响,二者分别保持在3.0%和750t/h时运行效果较好,且利于消除屏式过热器结焦;调整同层燃烧器外二次风挡板开度可减轻沿炉膛宽度的氧量不均;燃用设计煤种、全关燃尽风喷口外二次风挡板、保持燃烧器中心风母管风门开度为50%并在满负荷时尽量停止一层上排燃烧器利于降低飞灰中碳的质量分数。调整后测得锅炉效率超过94.4%,NOx排放浓度低于300mg/m3,明显优于国内目前运行的锅炉。     

立体分级燃烧对NO_x排放特性的影响

采用水平浓淡燃烧器及燃尽风联用的立体分级燃烧技术,对某台220 t/h燃烟煤、矩形炉膛锅炉机组进行降低NOx排放的改造,并对其进行试验研究.重点考察水平浓淡燃烧器、二次风配风方式和不同燃尽风份额对NOx排放量、炉膛温度水平、CO、CO2的影响规律.研究表明,采用新型水平浓淡燃烧器后,在强化燃烧的同时,可降低13%左右的NOx排放量;二次风配风方式对NOx排放影响明显,采用倒宝塔配风方式可降低NOx排放浓度至408 mg/m3;在燃尽风份额分别为0、0.21、0.31和0.43时,除出口氧量增加外,CO、CO2、飞灰碳体积分数变化不大,主燃烧区域温度水平总体呈降低趋势,燃尽区温度水平呈现先增加后降低趋势,NOx排放浓度持续降低.在未投三次风情况下,NOx排放浓度可降低到363 mg/m3.改造后,NOx排放浓度可稳定在450 mg/m3以下,为浓淡燃烧与燃尽风联用技术在大容量锅炉机组上的推广提供重要技术依据.     

稳燃特性对1000MW超超临界锅炉NO_x排放特性影响的数值模拟

使用可实现k-ε双方程模型,对一台1 000 MW超超临界对冲旋流燃烧锅炉NOx生成特性进行数值模拟。对燃烧器拟改进结构与原始结构NOx生成特性进行对比,并对燃烧器稳燃特性增强后过量空气系数、燃尽风(After air port,AAP)与侧燃尽风(Side air port,SAP)率、燃烧器投运方式及锅炉负荷等因素对NOx排放特性的影响进行计算。计算与分析结果表明,燃烧器稳燃特性增强后炉膛温度场变化较大,无油点火燃烧器温度场变化也非常明显,锅炉NOx排放量无明显增长;同时,根据NOx沿炉高方向的变化规律,可以将炉膛沿炉高分为浓度迅速升高、浓度缓慢下降、浓度快速下降和浓度缓慢上升4个区段,AAP与SAP风率越高、过量空气系数越小,炉膛出口NOx排放越少;同等负荷条件下,投入下层燃烧器数量较多时NOx排放量明显下降。并将计算结果和改进前后试验数据进行对比,计算误差在10%以内,数值模拟结果比较准确地预测了燃烧器改进后NOx生成与排放量,为燃烧器的设计和运行提供一定的理论依据。     

330MW神华煤锅炉燃烧优化调整试验研究

神华煤锅炉在运行过程中虽然掺烧了25%的高灰熔点煤,但仍普遍存在着排烟温度偏高、炉膛结焦等问题,锅炉经济性也有进一步提高的潜力。现针对某电站330 MW锅炉进行了优化燃烧调整试验,分析了运行氧量、负荷、煤粉细度、磨运行方式、一次风量(温)、周界风开度、燃尽风开度、配风方式、燃烧器摆角等参数对锅炉效率、结焦和NOx排放等的影响。在兼顾锅炉防结焦、高效和低NOx排放的基础上,推荐了锅炉运行方式,达到了优化锅炉运行的目标。     

中二次风水平摆角对炉内流场的影响

燃煤锅炉NOx的排放对环境的污染非常严重,发展洁净煤发电技术已经成为当务之急。针对某电厂9号炉的NOx排放量较高的问题,提出水平浓淡燃烧器和摆动中二次风相结合的方案。通过对改造后锅炉试验数据的研究,可知增大中二次风摆角对煤粉炉的影响较大。对数值模拟结果和试验研究数据进行了对比分析,两者吻合情况较好。结果表明：随着中二次风摆角增大,二次风切圆直径大于一次风切圆直径,形成“风包粉”的环境,有利于降低NOx的排放量。     

台山电厂1000MW超超临界蒸汽锅炉燃烧优化调整研究

对机组锅炉的运行特性调整进行研究,主要调整项目有:省煤器出口氧量标定调整、变氧量调整、二次风配风方式调整、变一次风速调整、变一次风温调整、变煤粉细度调整、炉膛—风箱差压变化调整、变燃烬风开度调整、燃烧器摆角调整、SOFA水平摆角调整、制粉系统组合方式调整、不同负荷下锅炉NO_x排放特性调整,以优化运行参数,保证锅炉安全、经济、环保运行。     

谏壁发电厂9号炉低NOx燃烧技术改造分析

详细介绍了国电谏壁发电厂9号炉为了降低锅炉烟气的氮氧化物（NOx）排放浓度,而进行的低NOx燃烧器和空气分级燃烧相结合的技术改造。运用了通用的降低NO。的生成的原理,分析了NOx排放浓度降低的原因。改造后的实践证明,氮氧化物（NOx）排放浓度得到了大幅度的降低,且锅炉的燃烧状况也得到了一定的优化。     

Minimal Realization of Linear Graph Models for Multi-physics Systems

An engineering system may consist of several different types of components,belonging to such physical"domains"as mechanical,electrical,fluid,and thermal.It is t...     

INTEGRAL EQUATION METHOD＇S APPLICATION IN HOLE-EDGE STRESS OF COMPOSITE MATERIAL PLATE WITH DIFFERENT SHAPED HOLES

The strength of composite plate with different hole-shapes is always one of the most important but complicated issues in the application of the composite material. The holes will lead to mutations and discontinuity to the structure. So the hole-edge stress concentration is always a serious phenomenon. And the phenomenon makes the structure strength decrease very quickly to form dangerous weak points. Most partial damage begins from these weak points. According to the complex variable functions theory, the accurate boundary condition of composite plate with different hole-shapes is founded by conformal mapping method to settle the boundary condition problem of complex hole-shapes. Composite plate with commonly hole-shapes in engineering is studied by several complex variable stress fimction. The boundary integral equations are founded based on exact boundary conditions. Then the exact hole-edge stress analytic solution of composite plate with rectangle holes and wing manholes is resolved. Both of offset axis loadings and its influences on the stress concentration coefficient of the hole-edge are discussed. And comparisons of different loads along various offset axis on the hole-edge stress distribution of orthotropic plate with rectangle hole or wing manhole are made. It can be concluded that hole-edge with continuous variable curvatures might help to decrease the stress concentration coefficient; and smaller angle of outer load and fiber can decrease the stress peak value.     

Non-monotonic material contrast in scanning ion and scanning electron images

30 keV Ga⁺ focused ion beam induced secondary electron (iSE) imaging was used to determine the relative contrast between several materials. The iSE signal compared from C, Si, Al, Ti, Cr, Ni, Cu, Mo, Ag, and W metal layers does not decrease with an increase in target atomic number Z₂, and shows a non-monotonic relationship between contrast and Z₂. The non-monotonic relationship is attributed to periodic fluctuations of the stopping power and sputter yield inherent to the ion–solid interactions. In addition, material contrast from electron-induced secondary electron (eSE) and backscattered electron (BSE) images using scanning electron microscopy (SEM) also shows non-monotonic contrast as a function of Z₂, following the periodic behavior of the stopping power for electron–solid interactions. A comparison of the iSE and eSE results shows similar relative contrast between the metal layers, and not complementary contrast as conventionally understood. These similarities in the contrast behavior can be attributed to similarities in the periodic and non-monotonic function defined by incident particle–solid interaction theory.     

Application of Feature Extraction through Convolution Neural Networks and SVM Classifier for Robust Grading of Apples

This paper proposes a novel grading method of apples,in an automated grading device that uses convolutional neural networks to extract the size,color,texture,an...     

分布动态载荷识别的抗噪处理

针对正交多项式频域法在用多种响应对矩形薄板进行载荷识别中抗噪性较差的问题,综合运用平均法、矩阵预处理和奇异值截断法等方法对之进行改善,并引入空间映射的思想,将该方法的应用范围拓展为复杂的模型.利用仿真算例,证实了该方法具有较好的抗噪性.     

基于MELTAC-N平台的核电厂安全级DCS环网研究与测试

针对工程实践中环网通讯相关问题的处理缺乏理论基础及国产化安全级DCS平台的开发缺乏成熟经验借鉴问题,对基于MELTAC-N平台核电厂安全级DCS环网的软硬件实现进行了研究。提出了安全级DCS环网双环网冗余设计、光切换开关设计等硬件设计方法,以及以RPR协议为基础,采用全数据收发策略的软件设计方法。在CPR1000安全级DCS平台上对安全级DCS环网的可靠性及实时性进行了评价,并进行了容错能力、响应时间及响应时间稳定性测试验证实验。结果表明,基于MELTAC-N平台安全级DCS环网软硬件设计具有较好的容错能力及响应时间稳定性。     

Short-Term Relay Quality Prediction Algorithm Based on Long and Short-Term Memory

The fraction defective of semi-finished products is predicted to optimize the process of relay production lines, by which production quality and productivity ar...     

End-to-End Multiview Gesture Recognition for Autonomous Car Parking System

The use of hand gestures can be the most intuitive human-machine interaction medium.The early approaches for hand gesture recognition used device-based methods....     

The laboratory simulation of abrasive wear

Abrasive wear has long been recognised as one of the most potentially serious tribological problems facing the operators of many types of plant and machinery; several industrial surveys have indicated that wear by abrasion can be responsible for more than 50% of unscheduled machine and plant stoppages. Locating the operating point of a tribological contact in an appropriate operational ‚map’︁ can provide a useful guide to the likely nature and origins of the surface degradation experienced in use, though care must be exercised in choosing the most suitable parameters for the axes of the plot. Laboratory testing of materials and simulations of machine contacts are carried out for a number of purposes; at one level for the very practical aims of ranking candidate materials or surface hardening treatments in order of their wear resistance, or in an attempt to predict wear lives under field conditions. More fundamentally, tests may be aimed at elucidating the essential physical mechanisms of surface damage and loss, with the longer term aim of building an analytical and predictive model of the wear process itself. In many cases, component surface damage is brought about by the ingress of hard, particulate matter into machine bearing or sealing clearances. These may be running dry although, more usually, a lubricant or service fluid is present at the interface. A number of standardised wear test geometries and procedures have been established for both two- and three-body wear situations, and these are briefly described. Although abrasive wear is often modelled as following an ‚Archard’︁ equation (i.e. a linear increase in material loss with both load and time, and an inverse dependence on specimen hardness) both industrial experience and laboratory tests of particularly lubricated contacts show that this is not always the case: increasing the hardness differential in an abrasively contaminated lubricated pair may not always reduce the rate of damage to the harder surface.     

ANGULAR DISTORTION ALLOWABLE VALUE AND ASSESS METHOD OF WELD ON COKE TOWER

A graph as the new engineering method for estimate the safety of bulging deformation of coke tower is proposed. Through stresses analysis of circumferential weld of coke tower and comparing the stresses produced by pressure with heat stress of steady state, residual stress, bending stress produced by both itself weight and wind loads, it showed that the stresses produced by pressure on the angle distortion are the main factor of equivalent stress of the combined stress. After comparing four kinds of stress controlling conditions, the relation to stress with depth of angular distortion, grade of curvature of angular distortion and half of region of angular distortion has been inferred. Graph of deformation allowable value of coke tower for different condition by angular distortion and half of region of angular distortion has been plotted. The five steps for its engineering use have been explained. The lighter the grade of curvature is, the larger of bulge allowance, may be, and the bigger of depth of angular distortion may pose too. For the coke tower with a popular structure of Dg 5 400 mm×28 mm, the result by graph is nearly more than the result of two formulas formed by other research, the error is less than 7.0%. But, the graph can be easily applied to different size of angular distortion.