低NO_x排放高温空气燃烧技术的研究

利用Fluent数值模拟软件分析了空气分级技术对高温空气燃烧及污染物排放控制的影响。应用空气分级及高温空气燃烧技术的燃烧器不仅提高了燃料理论燃烧温度、温度均匀性及燃烧效率,同时大大降低了NOx排放量,实现了高效燃烧与降低污染物排放一体化综合效果。计算结果分析表明,空气分级燃烧的二次空气配比对燃烧室内的NOx排放有较大影响,当一次空气占40%左右时NOx排放最少。     

降低热媒炉NO_x排放量的数值分析及验证

对某热媒炉NOx排放量超标的问题进行研究。采用CFD手段,对其进行结构优化设计;采用空气分级燃烧技术,预测NOx排放,得到了不同工况下的炉内温度及O2、CO和NOx等浓度分布。数值预测和试验结果都表明:在采用空气分级燃烧技术的情况下,增大二次空气量可以有效地减少NOx的生成排放,很好控制燃烧产物对大气的污染;在数值模拟中观察到随着二次空气量的增加,炉膛最高温度和平均温度降低,火焰或向一侧偏斜。该研究为空气分级低NOx燃烧系统改造效果的预报和应用提供重要参考依据。     

几何结构影响高温空气燃烧特性的数值分析

通过改变燃料喷口周围空气喷口分布夹角,采用数值计算的方法研究了高温空气燃烧特性的变化,包括燃烧温度场、速度场和NOx的生成和出口排放情况。模拟结果说明,减小空气分布夹角可以降低燃烧区最高温度和平均温度,扩大燃烧室内低氧范围,有效抑制热力型NOx的生成和排放。所采用的计算模型和计算方法可以较好地模拟高温空气燃烧过程,计算结果可信。     

顶燃式热风炉分级燃烧技术应用

选择2500 m3高炉的卡鲁金顶燃式热风炉燃烧器为研究对象,开发设计助燃空气分级燃烧器以降低NOx的排放.研究结果表明,空气分级燃烧器,先使高炉煤气在缺氧的环境中燃烧,燃烧后再通过下层的空气进一步燃烧,使燃烧室出口最高NOx浓度由308.74 mg/m3降到193.7 mg/m3,降低了37.26％.     

射流参数对单烧嘴燃烧室高温空气燃烧特性的影响的数值研究

以工业炉的高温空气燃烧技术应用为背景,对一个单烧嘴燃烧室内的高温空气燃烧特性进行了数值研究。燃烧室尺寸为800 mm×800 mm×1 400 mm,燃烧器烧嘴由燃气和高温预热空气多股射流组成,其中燃料射流喷口为圆形,直径为10 mm,位于中心。空气射流喷口为5个等面积的圆形,置于燃气射流喷口周围。湍流输运方程采用标准k-ε双方程模型,气相燃烧模型采用β函数的PDF燃烧模型,辐射换热过程采用离散坐标法模拟,NOx模型为热力型NOx。对燃气射流和空气射流的进口参数对燃烧室内的燃烧特性的影响进行了模拟计算和分析。计算结果表明射流进口参数将影响和改变燃烧室内的烟气回流及其与燃料、空气的混合过程,从而影响局部温度、氧浓度的分布和决定燃烧状况、影响最终的NOx排放量。其中随着燃料射流和空气射流速度比和燃料射流倾角的增大,燃烧室内的烟气回流区域扩大,强化了燃料、空气和烟气的混合,使低氧区域扩大,燃烧室内最高温度和平均温度都降低,NOx生成量明显降低。研究结果对于工业炉的烧嘴设计有一定参考意义。     

矩形空气喷口长宽比对高温空气燃烧NOx排放的影响

高温空气燃烧技术中,在燃气喷口两侧布置矩形空气喷口,且矩形空气喷口的长轴指向燃气喷口,有利于在炉膛内形成低氧、低燃气浓度的高温燃烧环境.本文利用计算流体力学软件研究了矩形空气喷口长宽比在高温空气燃烧过程中对N0x排放的影响.研究结果表明,在本文所研究的炉膛结构条件下,矩形空气喷口长宽比为1.5、空气喷口与燃气喷口的间距为43 mm时,NOx排放能够得到有效的控制.     

高温空气燃烧炉内燃烧特性的数值研究

采用数值模拟法,研究了高温空气燃烧炉内不同空气预热温度、氧气浓度和燃气入口温度对火焰特性和NOx生成和排放的影响规律。研究表明,在提高空气预热温度、降低氧气浓度条件下,在较大范围内进行燃烧,火焰体积变大,炉内温度的峰值相应降低,温度分布更均匀,NOx的生成量大幅度降低。提高燃气入口温度,可抑制燃料和空气在主燃烧区的混合,使火焰内反应物的分布更加均匀,抑制了热力NO的生成,从而减少了NOx的排放量。     

助燃空气O2浓度对熔铝炉内温度分布及NOx生成量影响

烟气再循环技术是降低熔铝炉能源消耗和NOx排放的有效途径.为此,利用FLU-ENT软件对采用烟气再循环技术的某熔铝炉的燃烧过程进行数值模拟计算,分析了助燃空气中的O2浓度对炉内温度分布的均匀性及NOx生成特性的影响.结果表明,助燃空气O2含量的降低有利于炉内气体的混合和稀释,有利于炉膛内温度的均匀分布,也有利于减少NO...     

旋流燃烧器旋流方式对燃烧特性的影响

对空气单旋、煤气单旋、直接喷射、空气煤气同向旋流、空气煤气异向旋流这五种旋流方式下的甲烷燃烧进行数值模拟,测量并分析了5种旋流方式对燃烧室内的燃烧温度、O2浓度、CO2浓度、NOx的生成、回流量的影响。结果表明:5种旋流方式的燃烧室温度和回流量都先升高再降低,单一气体旋流的NOx浓度远低于空气煤气双旋流的NOx浓度。     

高温空气平焰燃烧过程的数值分析与比较

通过数值模拟方式分析了高温空气平焰燃烧的特点。并从火焰结构、能量利用与NOx排放等角度，与常规平焰燃烧进行了比较。数值模拟结果显示。通过助燃空气预热来高效回收烟气余热，烟气再循环来获得低氧燃烧环境，减少NOx的生成与排放，在相同的加热能力与相同的NOx排放条件下，高温空气平焰燃烧可节能45％，减少温宣气体排放45％。     

Understanding Air Release through Air Valves

Water transients with entrapped air can originate large pressure peaks that can severely damage distribution networks. Entrapped air can have a damping or amplifying effect on these undesirable pressure peaks. Unfortunately, the complexity of the phenomenon too often makes it difficult to obtain a fully reliable prediction about when air pockets will mitigate or accentuate water transients. Furthermore, the value of some of the parameters involved in the conventional numerical models cannot be calculated or measured and need to be determined through a calibration process. With the aim of overcoming most of the aforementioned uncertainties, this paper summarizes a complete set of tests conducted at WL | Delft Hydraulics. These tests were simulated by means of a tailored numerical model that includes a set of parameters whose values were determined by means of a calibration process. The experimental setup, a large-scale facility, consisted of a single steep pipeline with an air valve installed at its top end. Air release through different air valves was tested under different conditions.     

浅谈剧场空调送风方式

介绍了目前剧院工程中观众厅所采用的上送下回、诱导空调椅送风和置换通风等气流组织形式的特点以及舞台、后舞台、台仓空调送风方式。     

Numerical Modeling of Air Losses in Compressed Air Tunneling

A numerical model has been developed to predict the air losses from tunnel face and perimeter walls in compressed air tunneling. The model can also predict the zone of ground influenced by air flow from the face and walls of a lined and unlined tunnel. The model comprises a finite element analysis of the flow of air from the tunnel face and an analysis of the flow from the tunnel perimeter walls based on flow laws. The numerical model considers the stages in the construction sequence, geometry of the tunnel, soil layers, and time. Furthermore, the model accounts for the curing behavior of shotcrete, in particular, the time dependency of permeability. Field data from the Feldmoching Tunnel, U8 N‐8 in Munich, Germany, has been used as a case study to verify and calibrate the numerical model. The results of the analysis indicate that this model is suitable for predicting air losses in compressed air tunneling. Furthermore, the model predicts the areas of ground that are likely to be affected by the flow of air from the tunnel. This information can be used to assess the risk of settlement and other indirect consequences of the tunneling method.     

Measuring Air Leakage Characteristics with Flexible Double Air Chambers

The fan pressurization method for measuring air leakage through the building envelope relies on the assumption that the extraneous air leakage (EAL) through paths other than those through the specimen being tested is negligible. When EAL does exist, the calibration procedure by ASTM Standard E-283 is used to measure EAL values by covering the specimen or guarded chambers are used to equalize the pressure differences across these unintended paths. A new testing method, the flexible double-chamber method, is presented in this paper for large specimens where the above two approaches are difficult to implement and where flexible chambers are more easily applied. The experimental procedure and data processing routine are presented for the case of a full-size metal curtain wall specimen. The EAL is estimated by regression analysis in data processing. Inference analysis, multivariate error analysis, and the Monte Carlo simulation technique are also presented to examine the estimation errors.     

零气耗余热再生空气干燥器应用

介绍了零气耗余热再生空气干燥器原理、特点及应用条件,并针对首钢京唐公司压缩空气系统现有问题提出了解决方案。通过在现有高气耗空压机系统中应用零气耗余热再生空气干燥器,既节约了再生耗气量,又节省了电力能源的消耗。     

Air weapon fatalities

AIMS: To describe characteristics of a series of people accidentally and deliberately killed by air powered weapons. METHODS: Five cases of fatal airgun injury were identified by forensic pathologists and histopathologists. The circumstances surrounding the case, radiological examination, and pathological findings are described. The weapon characteristics are also reported. RESULTS: Three of the victims were adult men, one was a 16 year old boy, and one an eight year old child. Four of the airguns were .22 air rifles, the other a .177 air rifle. Two committed suicide, one person shooting himself in the head, the other in the chest. In both cases the guns were fired at contact range. Three of the cases were classified as accidents: in two the pellet penetrated into the head and in one the chest. CONCLUSIONS: One person each year dies from an air powered weapon injury in the United Kingdom. In addition there is considerable morbidity from airgun injuries. Fatalities and injuries are most commonly accidents, but deliberately inflicted injuries occur. Airguns are dangerous weapons when inappropriately handled and should not be considered as toys. Children should not play with airguns unsupervised.     

XF-100空压机气源净化处理改进

多功能天车XF-100空压机气源净化不合理，引发气动系统故障，介绍采取的相应改进措施，效果好。