非均质孔隙率采空区氧化升温规律四维动态模拟

运用Fluent动网格模型实现采空区的四维动态变化,并用用户自定义函数将煤低温氧化动力学机理及非均质孔隙率函数编入Fluent中,结合时间和空间,对U+L型通风系统采空区升温规律进行四维动态模拟研究.研究表明:非均质孔隙率四维动态模型能更真实地反应孔隙率的空间与时间变化,空间某一位置的孔隙率随时间呈负指数递减;工作面推进速度越大,采空区升温速率越小,推进速度为3.6 m·d-1时平均升温速率仅为推进速度为1.2 m·d-1时的1/5;然而,推进速度越大,高温点的深度越大,不利于自燃的预防;尾巷的存在使得温度场范围扩大,温度升高,CO主要从尾巷流出,尾巷释放的CO量是回风巷CO释放量的10倍.最后利用现场实测的数据对结果进行验证,表明模拟结果是正确可信的.      

Y型通风下采空区自燃CO蔓延规律仿真研究

为探明Y型通风下采空区煤自燃发火温度、CO的分布规律;采用Pyro Sim火灾仿真软件,分别构建火源位置、风速不同的6种工况的采空区模型,进行数值模拟,比较各工况下温度、CO的分布、蔓延规律;研究发现:采空区煤自燃发火时温度的分布与火源位置及风速关系不大;CO的蔓延与火源位置及风速有关,当火源位于采空区中间时,CO向回风巷侧蔓延,火源位于采空区左侧时,CO向回采工作面蔓延,风速越大CO越容易蔓延至工作面;当不知火源位置时,若需要对CO钻孔导流,则孔钻的位置最好靠近采区工作面。     

综放工作面高抽巷合理位置的研究

针对高抽巷抽采瓦斯条件下诱发采空区自燃发火问题,以某矿综放工作面实际开采的技术条件构建采空区气体渗流模型,结合实际高抽巷布置要求,利用Fluent数值模拟软件分析高抽巷不同平距和垂距条件下的采空区氧化带宽度,结果表明:当高抽巷垂距为35 m、平距为25 m时,采空区氧化带宽度最小。高抽巷合理位置的确定,在提高瓦斯抽采效率、减小煤自燃发火的危险性、保证综放工作面的绿色、安全、高效等方面具有实际的指导意义。     

易自燃煤层综放工作面综合安全保障技术研究

综放开采具有产量高、效益显著等优点,但受开采方式影响采空区内遗煤量较大,采空区遗煤自燃发火危险性较高,如何避免采空遗煤自燃是综放工作面开采时需要重点解决的问题.采用综合安全保障技术是实现降低采空区遗煤自燃危险的重要举措.为此,对现阶段矿井常用的防灭火技术展开分析,并以5306综放工作面回采为工程实例,对综合安全保障技术...     

回采工作面回撤期间防灭火技术

自燃煤层回采工作面设备回撤期间采空区遗煤存在较大自燃风险,针对3506采煤工作面设备回撤期间采空区遗煤自燃风险较高问题,提出构建以注氮为核心的综合防灭火技术,现场应用效果显著,回采工作面回撤期间采空区内CO浓度均在较低范围内,回撤通道未监测到CO。研究成果可为矿井其他回采工作面回撤工作开展提供经验指导。     

沿空留巷工作面采空区综合防灭火技术研究

为确保1506沿空留巷工作面回采安全,针对采面初采以及过断层期间推进速度慢、遗煤量增加等导致采空区遗煤自燃发火危险性增高问题,提出将综合防灭火技术应用到采空区遗煤自燃发火防治中.并根据现场实际情况,对综合防灭火技术参数进行设计.现场应用后,采面在初采、过断层期间采空区内CO浓度(体积分数)均控制在15×10-6以内,其...     

斜沟煤矿23103综采工作面控制风量防灭火技术研究

以西山晋兴公司斜沟矿23103综放工作面为案例,分析了该工作面在回采过程中采空区遗煤易自燃的问题,结合23103综放工作面的实际生产情况,在对采空区遗煤分布和漏风情况进行分析研究基础上,通过采取构筑隔离墙、注氮和降低供风量的综合防灭火措施,降低采空区遗煤自燃隐患,保证了工作面安全顺利回采及设备搬迁,实践取得显著的社会与经济效益,同时对矿井地质条件相类似的矿井易自燃厚煤层放顶煤开采具有借鉴意义。     

综放工作面回风上隅角CO超限分析及防治技术研究

20503综放工作面开采的5号煤层为褐煤,受到开采工艺以及地质构造等因素综合影响,采面采空区内遗留有大量的遗煤,遗煤氧化导致采面回风上隅角位置CO超限。为实现采面CO涌出超限的有效治理,提出综合使用采空区埋管、喷洒阻化剂、均压通风以及帷幕注氮等方式进行治理,采取的措施可抑制采空区遗煤氧化进程,并减少采空区CO向回采空间涌出量。现场应用后,回风上隅角位置CO浓度控制在8×10^-6以内,取得较好防治效果。     

综采工作面采空区防灭火技术应用

针对某矿30905综采工作面回采期间回风隅角CO浓度超限的问题,在分析导致CO浓度过高的原因基础上,提出综合注氮、减少漏风以及调整过断层方法等措施,并采用JSG5型监测系统提高采空区遗煤自燃发火监测精度。现场应用后,采空区内O2浓度（体积分数）降低至4.3%以内,CO浓度（体积分数）降至9×10-6以内;同时采面保持较快推进速度,在后续过断层间,采面回风隅角未能监测到CO,取得较好的采空区防灭火效果。     

U型通风工作面瓦斯治理效果分析

针对"U"型通风系统存在的问题,屯兰矿12507综采工作面采用全方位的抽采措施后,将上隅角瓦斯控制在0.3％以下,回风巷瓦斯控制在0.4％以下,有效解决了"U"型通风上隅角瓦斯积聚的问题,确保了安全生产.     

Utilization and recycling of low-temperature waste heat of stainless steel continuous annealing furnace

Stainless steel continuous annealing furnace is mainly used for heat treatment of hot-rolled strip steel.The combustion air will be enabled to heat to 520℃by waste heat recovery system,but the discharge temperature is still up to about 300℃.Owing to with development of global emphasis on energy conservation energy saving and discharge reduction,it’s significant to lower the discharge temperature to below 200℃, for the sake of achieving rational use of waste heat resource.Through the analysis of the existing heat recovery system by this study,it is proved that mixing low temperature with flue gas in high temperature standard will increase the capacity of the flue gas and deteriorate the quality of remaining heat resource.In stead of that,increasing the combustion air temperature to 600℃on the basis of stability temperature for the prerequisite of recuperator design,and giving priority to reducing fuel consumption are the better way.The recovery and recycle of low temperature gas are also be introduced.It is demonstrated by the way of setting a secondary recuperator at the exit of the primary recuperator,and using low temperature flue gas to heat the air used for drying the strip steel,the exhuast temperature of flue gas can be reduced to lower than 200℃.At the same time,the steam required for heating air is saved,the energy reserve as high as 2 300 t of standard coal per year.     

固体热载体煤气化试验装置提升段燃烧试验

固体热载体煤气化的热量靠提升燃烧产生。介绍了褐煤焦载热煤气化提升燃烧的点火、燃烧和调节。根据点火曲线，可将其分为加热、着火和燃烧三个阶段。调节提升风量能很好地控制燃烧工况，加大气化煤量可增加提升燃烧的易燃成分，从而提高燃烧温度。     

Application and practice of regenerative combustion technology on radiant-tube furnace

High Temperature Air Combustion(HTAC) based on regenerative theory has been used in developed countries in recent years,it has many advantages such as efficient recovery of waste heat,high temperature preheating air,low pollution discharge,and so on.This Technology can be used in various furnaces in mechanical,petroleum,chemical industry.To rebuild traditional radiant-tube combustion system with HTAC technology has become important.In the transformation process,The biggest difficulty encountered is that the stability of burner combustion and control system. Because the exhaust gas heat is absorbed by the regenerator,exhaust gas discharge can be controlled at a very low temperature to realize maximum waste heat recovery.At the same time,it improves the temperature uniformity and improve the heating intensity.Thermal efficiency of the device can reach more than 80%.And compared to the traditional air preheating,21.55%energy can be saved. Revamping on traditional radiant-tube combustion system is technically feasible,but a lot of problems will be involved since the rebuild work is on the old system,this article discusses on the main problem encountered in rebuild process in site. to optimize temperature control and obtain not so high exhaust gas temperature,digital combustion control system is necessary.This control loop consists of big loop and small loop,Big loop controls the load distribution of all burners in each heating zone.Small loop controls each heating zone burner’s burning time. Compared performance of tradition radiant-tube heater with regenerative radiant-tube heater,result that regenerative radiant-tube heater have many advantage in consume fuel.Accordance with experience of replacing tradition radiant-tube heater with regenerative type,give a proposition in combustion control system, pilot burner,flame detection and prevent trouble to rebuild work of CAPL and CGL. It is recommended to use regenerative combustion technology in new annealing Line.Although the investment is 1/3 much more than the traditional combustion system,the energy saving effect is obvious and operating costs decreases.Revamping can be taken step by step according to different heating zones.Although taking a long time,it is safer and it influences the production less. Regenerative combustion burner revamping has become successful.However,the revamping work on different furnaces,particular on continuous annealing furnace with high request for temperature control,need further exploration and research.     

特厚钢板阵列射流淬火的表面换热

采用特厚钢板专用辊式射流淬火试验装置和多通道钢板温度记录仪,测试出射流速度3.39~26.8 m·s-1、雷诺数12808~117340、水流密度978.7~6751.5 L·(m2·min)-1条件下,84 mm厚钢板淬火冷却曲线;进而基于反传热修正方法计算高温钢板淬火过程壁面温度和热流密度,描绘出沸腾曲线,分析多束圆孔阵列射流对特厚钢板淬火表面换热的影响.结果表明:射流速度、水流密度等参数影响钢板表面射流滞止区和平行流区换热机制,进而影响最大热流密度分布.射流速度较低时,壁面平行流区观察到混合换热和"热流密度肩"现象;随射流速度增大,膜沸腾换热机制消失,最大热流密度移至较低壁面过热度处.相关研究将对特厚钢板淬火过程温度场计算和组织性能调控提供有益的帮助.      

正转链条炉排锅炉分层燃烧技术应用初探

指出了正转链条炉排锅炉闸板式给煤存在的种种弊端：通风受阻、布风不均、锅炉热效率低、炉膛温度上不去、热损失大等;对５＃ 锅炉应用分层燃烧技术进行了改造,详细分析了改造后取得的效果。     

氧煤燃烧熔分炉炉料沉降与传热行为数值模拟

 回转窑预还原-氧煤燃烧熔分炼铁工艺直接使用宽粒级的粉矿入炉,炉料颗粒经回转窑内煤气逆流换热和预还原后,通过沉降管到达氧煤燃烧熔分炉。为避免沉降区域内炉料颗粒冲刷炉壁、壁面堆积及气固传热不均现象,实现颗粒沉降与传热过程的耦合控制,最大限度降低炉料与熔池温度差,保证熔池熔炼稳定,达到良好的冶炼效果,利用计算流体力学-离散单元法(CFD-DEM)研究氧煤燃烧熔分炉熔池上部区域煤气流速和炉料粒径对炉料颗粒在逆流煤气作用下的沉降轨迹与传热行为的影响。数值模拟结果表明,随着煤气流速增大,炉料颗粒的沉降速度减小,煤气对小粒径炉料颗粒的作用尤为明显。煤气流速为1 m/s时,每种粒径的炉料颗粒沉降效果良好;煤气流速为2 m/s时,粒径为1.0、1.5、2.0 mm的炉料颗粒沉降效果相对较好;煤气流速为3 m/s时,粒径为1.5、2.0 mm的炉料颗粒能够顺利沉降。针对炉料颗粒传热行为,煤气流速越大,炉料粒径越小,则炉料颗粒的传热效果越好。综合炉料传热与沉降行为,粒径为1.0 mm左右的炉料颗粒在煤气流速为1和2 m/s作用下,炉料颗粒的沉降速度和传热情况均良好。     

Influence of oxide scales on heat transfer in secondary cooling zones in the continuous casting process,part 1: heat transfer through hot-oxidized steel surfaces cooled by spray-water

For the cooling of steels in the continuous casting process it is necessary to know the heat transfer from the solidifying strand to the cooling water to enable calculation of the secondary cooling zone. Previous investigations have only determined this variable for non-oxidizing metallic surfaces. For many steels cast in practice, however, the formation of oxide layers prevents a direct transfer of the previous results. In the present research the influence of the oxide layers on the heat transfer has been investigated for spay-water cooling. Results have shown that heat transfer in the range of stable film boiling is determined for a constant spray-water temperature in the same way as for non-oxidizing metals, i.e. using the water mass flux density ·_s only. The changed surface qualities resulting from the oxide formation cause the Leidenfrost temperature, however, to shift considerably to higher values.     

Combustion Property and Kinetic Modeling of Pulverized Coal Based on Non-isothermal Thermogravimetric Analysis

Non-isothermal combustion kinetics of two kinds of low volatile pulverized coals （HL coal and RU coal） were investigated by thermogravimetrie analysis. The results show that the combustibility of HL coal was better than that of RU coal, and with increasing heating rate, ignition and burnout characteristics of pulverized coal were improved. The volume model （VM）, the random pore model （RPM）, and the new model （NEWM） in which the whole combustion process is considered to be the overlapping process of volatile combustion and coal char combustion, were used to fit with the experimental data. The comparison of these three fitted results indicated that the combustion process of coal could be simulated by the NEWM with highest precision. When calculated by the NEWM, the activation energies of volatile combustion and coal char combustion are 130.5 and 95.7 kJ · mol^-1 for HL coal, respectively, while they are 114.5 and 147.6 kJ ·mol^-1 for RU coal, respectively.     

高炉理论燃烧温度计算的研究

 理论燃烧温度是判断高炉炉缸热状态的重要参数之一。 在深入分析现有理论燃烧温度计算模型存在问题的基础上,提出修正建议 ：绝热系统内除煤气之外还应包括燃料燃烧后的残留物及未燃煤粉;所有物质的比热容应是温度的函数;焦炭的温度应为高温区热平衡计算所得;同时,考察了这些修正因素对理论燃烧温度计算值的影响。