供风量对褐煤自燃极限参数的影响研究

为研究不同供风量对褐煤自燃特性的影响规律,选取平庄瑞安煤矿褐煤作为试验煤样,利用程序升温试验和气相色谱仪,研究低温氧化阶段不同供风量条件下褐煤自燃极限参数与温度、供风量之间的变化规律。结果表明:温度在40~120℃时,随着供风量增大,褐煤的最小浮煤厚度和下限氧浓度降低,上限漏风强度增加;温度在120~200℃,供风量为40~80 mL/min和160~200 mL/min时,随着供风量的增加,其最小浮煤厚度和下限氧浓度增加,上限漏风强度减少;供风量为80~160 mL/min时,在供风量增大的情况下,褐煤的最小浮煤厚度和下限氧浓度降低,上限漏风强度增加;随着供风量减小,煤样临界点温度降低。     

低温取芯过程热传递方式的数值模拟和实验研究

为了研究热量在低温取芯过程中传递的方式,以型煤为研究对象,使用自制低温取芯模拟装置,通过实验并结合数值模拟,对低温取芯过程热量传递方式进行研究,进而分析煤芯温度的变化规律。研究结果表明:甲烷的存在降低了煤样的热交换速率,使煤芯温度变化滞后于煤样罐壁温度变化;煤体内部温度分布存在差异,煤样中心轴线不同半径处的圆柱面构成变温过程的等温面,在降温过程,热量沿径向由煤样内部向外部传递,升温过程,热量沿径向由外部向内部传递;低温取芯过程热量传递同时存在3种方式:热传导、热对流,煤体表面与罐体内壁表面之间的热辐射,以热传导方式为主。     

基于T-P模型的高低温环境型煤对甲烷吸附性能预测

为预测深部或浅部煤层不同温度和不同压力条件下的吸附等温线,选用型煤以高低温试验装置为依托,测试了温度为293.15,273.15,253.15 K的吸附等温线。基于T-P模型,利用等温吸附曲线对公式中的参数进行了合理的求解,探讨了一种简单的煤对瓦斯吸附等温线预测方法。研究表明:同一吸附平衡压力下,温度越低,煤的瓦斯吸附量越大;ε－ω吸附特征曲线与温度无关,呈现对数的形式;参数m和拟合度R2满足抛物线的关系,存在拟合效果最好时的参数m值。采用T-P模型预测得到的吸附等温线与实测的吸附等温线无论是趋势还是定量结果均十分吻合,其相对误差不超过5%。     

高温后砂岩抗拉强度及应变场演化实验研究

为研究高温后砂岩的抗拉力学特性及变形破坏规律,对不同温度作用后的砂岩进行巴西劈裂实验,同时采用数字散斑相关方法对砂岩变形破坏进行监测。研究表明:高温作用后砂岩质量损失率增加,波速整体呈降低趋势,砂岩物理特性出现一定劣化;高温作用使砂岩抗拉强度呈先增加后减小的趋势,25~400℃增大了16.08%,400~1 000℃减小了69.30%,砂岩表现为脆性破坏特征;砂岩劈裂过程中,水平应变场演化过程为:局部小变形产生、扩展→小变形区域聚集、合并、连接→应变局部化带产生→应变局部化带扩展并贯穿→宏观劈裂破坏;随着温度升高,应变局部化启动水平先增加后降低,400℃为转折点。该研究方法可为煤矿火灾安全等领域提供借鉴。     

冷板冻结物理模拟试验研究

为了提升地铁工程盾构管片破损抢险应急救援能力,在广佛线某区间地铁隧道管片冻结封水工程中使用矩形截面的外置冻结器—冻结冷板。采用物理模拟试验,对混凝土结构外敷冷板冻结形式下的冻结规律进行系统研究,研究单排冷板、双排冷板及冻结盘管的冻结温度场变化规律,分析不同布置形式下冻结壁的界面、主面温度分布特征。研究结果表明:在冷板冻结形势下,主、界面温度分布曲线在浅部呈对数曲线形式,随深度的增加逐渐过渡成线性分布,冻结器与冻结介质的热交换面积大小对冻结效果影响比重大,适当的布置形式能大大提高冻结效率和效果。冷板冻结形式可以有效加强土层与混凝土结构交接面的冻结效果,提高交界面上胶结强度,提高冻结施工安全。     

向家坝水库水温时空特征及其成因分析

水温是水环境评价的重要因子之一,其对水生态系统中的物理、化学和生物过程起着重要作用。为了分析向家坝水库运行期内的水温分布特征及其成因,本文建立CE-QUAL-W2立面二维水温模型,并基于2014年野外原位监测水温数据对模型可靠性进行了验证,应用其对水温分布进行数值模拟。研究发现向家坝水库水温存在季节性垂向分层,4~6月中上层水体(水深0~60 m)受入流水温和气温回升影响迅速升温,表底温差达10℃,垂向分层加剧;7、8月水库泄洪加快了库区水体交换,底层水温迅速升高,中间等温层水体厚度增加,表底温差减小在2℃内,9月以后表底温差进一步缩小,垂向水温分层逐渐消失。通过分析发现:气象要素、入流水温、电站取水口高程、泄洪方式成为影响向家坝水温分布的主要因素。入流水温的变化只影响水库水温波动范围,对其垂向分层结构影响较低;表层水温受气象条件影响显著;取水口高程和泄洪方式决定了水温的垂向结构。     

Effect of flue gas recirculation on nitric oxide (NO) emissions during the coal grate-fired process

Flue gas recirculation (FGR) is a low nitrogen oxide (NO_X) combustion technology. The present study used standard gas to simulate the cycle gas (the main ingredients of which are oxygen (O₂), nitrogen (N₂), and carbon dioxide (CO₂)). The coal grate-fired process was divided into three zones, namely (1) volatilization zone, (2) main combustion zone, and (3) char combustion and burn-out zone. The effects of FGR on coal combustion and NO emissions were investigated in these zones of a unit-boiler experimental system. An industrial test was then conducted on a chain boiler that previously used FGR. Data showed that if the cycle gas was directed into the furnace from the volatilization zone, the curve of the coal surface temperature moved backwards, the temperature peak increased, and coal ignition was delayed. When the FGR rate was 20%, NO emissions/g coal was 41.8% less than in the absence of FGR, in the overall combustion process except for the volatilization zone. An industrial test demonstrated that FGR decreased the NO emissions and incomplete-combustion loss of gas. NO and carbon monoxide (CO) emissions were reduced by 26.9 and 38%, respectively. These observations may prove to be beneficial in reducing ambient air pollution and saving energy.     

Non-linear autoregressive neural network approach for inside air temperature prediction of a pillar cooler

The volcanic plate made pillar cooler system is designed for outdoor spaces as a heat exchanging medium and reduces the outcoming air temperature which flows through the exhaust port. This paper proposes the use of artificial neural networks (ANNs) to predict inside air temperature of a pillar cooler. For this purpose, at first, three statistically significant factors (outside temperature, airing and watering) influencing the inside air temperature of the pillar cooler are identified as input parameters for predicting the output (inside air temperature) and then an ANN was employed to predict the output. In addition, 70%, 15% and 15% data was chosen from a previously obtained data set during the field trial of the pillar cooler for training, testing and validation, respectively, and then an ANN was employed to predict inside air temperature. The training (0.99918), testing (0.99799) and validation errors (0.99432) obtained from the model indicate that the artificial neural network model (NARX) may be used to predict inside air temperature of pillar cooler. This study reveals that, an ANN approach can be used successfully for predicting the performance of pillar cooler.     

我国和东亚地区硫化物的大气输送研究——流场分型统计输送模式

提出了一种流场分型欧拉酸沉降输送模式,计算了1993年4月东亚地区硫氧化物平均浓度的时空分布以及我国各省区和东亚主要国家的硫沉降量?通过与实测资料对比,模式有较好的可信度,是一个计算硫氧化物长期平均浓度和硫沉降的简便?实用的酸沉降输送模式?      

电除尘器在气烧石灰竖窑炉顶高温烟气除尘中的应用

气烧石灰竖窑炉顶高温烟气除尘 ,采用静电除尘工艺 ,除尘效果明显 ,只要设计合理 ,可应用于气烧石灰竖窑炉顶高温烟气石灰粉尘治理中。