Experimental study on the influence mechanism of gas seepage on coal and gas outburst disaster

By using the self-developed triaxial servo-controlled seepage equipment for thermo-fluid-solid coupling of coal containing gas and the self-developed coal and gas outburst simulation test device, experiments to study the influence mechanism of gas seepage on coal and gas outburst disasters. The results show that: (i) gas seepage decreases the strength of coal containing gas and accelerates its failure process; (ii) under the same gas pressure, the confining pressure is larger, the more difficult the gas flows and the greater the intensity of coal containing gas is; (iii) in the process of coal and gas outburst, the greater the vertical ground stress is, the more powerful the outburst will be; (iv) the influence mechanism of gas seepage on coal and gas outburst disasters is as follows: firstly, gas seepage weakens the mechanical properties of coal body, which makes it much easier for coal and gas outburst to occur; secondly, on the same effect of external force, it will be easy to form a high gas pressure zone in the coal body under the difficult condition of gas seepage, and accumulate more gas compression energy, which is the energy source for coal and gas outburst, and it is also the main dynamic source to throw and grind the coal.     

Coupling effects of foam ceramics on the flame and shock wave of gas explosion

The coupling of gas explosion flame and shock wave is analyzed. In the gas explosion process, shock wave is affected by the flame directly, and shock wave also induces the flame. Inhibiting explosion can be achieved by the interference between the flame and shock wave propagation. If the coupling effects can be damaged, the adverse effects caused by the explosion should be mitigated and controlled. According to the structure characteristics of foam ceramics, the coupling effects mechanism of ceramic foam on gas explosion flame and shock wave is researched. When the explosion goes through the structure of foam ceramics, the flame can be quenched and the shock wave be attenuated. After the flame is quenched, the supply of precursor shock wave energy is cut off. Due to lack of energy supply, the destructive effects of blast wave will be reduced effectively. Coupling effects of the flame and shock wave can be damaged by the special structure of foam ceramics. Studies suggest that a certain function to represent the structure characteristics of foam ceramics must exist. For a certain material of foam ceramics, the sure porosity δ and the pore diameter d also can be get, which is the key to research and develop foam ceramic suppression technology of gas explosion.     

液化天然气储罐9％镍钢焊缝相控阵AUT工艺

9％镍钢液化天然气储罐制造安装过程中,焊缝检验通常用常规射线照相（RT）进行。本文研讨用相控阵半自动超声检测（AUT）取代射线照相的工艺制定及验证方法。要领分四步：首先带缺陷专用焊接试样的制备;然后相控阵AUT工艺的编制;其次在有已知缺陷的焊接试样上,对AUTT艺作“开放性”验证试验;最后在现场对整个数据采集系统作“封闭性”操作演示和验证评定试验。验证结果表明相控阵AUT取代RT可行可靠,能凸显AUT种种优势。     

Influence of vacuum degree on the effect of gas explosion suppression by vacuum chamber

In order to study the influence of vacuum degree on gas explosion suppression by vacuum chamber, this study used the 0.2 mm thick polytetrafluoroethylene film as the diaphragm of vacuum chamber to carry out a series of experiments of gas explosion suppression by vacuum chamber with the vacuum degree from −0.01 MPa to −0.08 MPa. The experimental results show that: under the condition of any vacuum degree, vacuum chamber can effectively suppress the explosion flame and overpressure; as vacuum degree changes, the effect of gas explosion suppression using vacuum chamber is slightly different. Vacuum chamber has obvious influence on propagation characteristics of the explosion flame. After explosion flame passes by vacuum chamber, the flame signal weakens, the flame thickness becomes thicker, and the flame speed slows down. With the increase of the vacuum degree of vacuum chamber, the flame speed can be prevented from rising early by vacuum chamber. The higher the vacuum degree is, the more obviously the vacuum chamber attenuates the explosion overpressure, the smaller the average overpressure is, and the better effect of the gas explosion suppression is. Vacuum chamber can effectively weaken the explosion impulse under each vacuum degree. From the beginning of −0.01 MPa, the vacuum chamber can gradually weaken explosion impulse as the vacuum degree increases, and the effect of gas explosion suppression gradually becomes better. When the vacuum degree is greater than −0.04 MPa, the increase of vacuum degree can make the explosion overpressure decrease but have little influence on the explosion impulse. Therefore, the vacuum chamber has the preferable suppression effect with equal to or greater than −0.04 MPa vacuum degree.     

Effects of release pressure on the transportation characteristics in pipeline and the diffusion behaviors in enclosure space of typical gas extinguishing agent

Reducing the release pressure of fire extinguishing systems can decrease potential safety hazards in large transport airplanes. To explore whether reducing the release pressure can achieve the release effect required by the airworthiness standards or not, the transportation characteristics in the pipeline and diffusion behaviors in the enclosure space of a typical fire extinguishing agent (Halon 1301) were investigated under five release pressures in the present study. The effects of the release pressure on the degree of superheat, injection duration, jet structure, and concentration distribution of Halon 1301 were analyzed. The results show that both of the degree of superheat and the injection duration decrease with an increase in the release pressure. The supplement of bubble expansion in the fire extinguishing agent can slow down the pressure decrease in the vessel. Both of the maximum and mean values of the pipeline differential pressure increase with an increase in release pressure. The maximum value of the jet angle decreases linearly with the increase in release pressure, and the jet deflects upward owing to the effects of buoyancy. The maximum concentration value decreases with an increase in the distance from the nozzle. The maximum concentration values in the near field from the nozzle increase with an increase in the release pressure. Under five release pressures, the concentration and holding time (duration above 6% volume concentration) of Halon 1301 on the centerline of the jet meet the requirements of airworthiness provisions.     

PVC电缆火灾早期特征气体的组成分析和传感器探测

利用气体传感器对电缆绝缘过热释放的气体进行监测有望实现电气火灾早期预警,目前该技术的发展由于特征气体未得到确认而受到限制。分析了聚氯乙烯(PVC)电缆绝缘层在不同温度下释放的气体组成,并对其主要成分进行传感器测试。TG-IR和GC-MS分析表明PVC电缆绝缘层在200℃前已出现微小失重,释放出以邻苯二甲酸二辛酯(DOP)等塑化剂为主的气体。气敏测试中,商用半导体气体传感器对DOP和电缆蒸气产生较好、相似的响应性能。因此,DOP可以作为PVC电缆火灾早期的特征气体。     

湿式煤气柜施工安全措施的制订

针对正在运行的湿式煤气柜防火间距不够的位置动火建造大10倍的湿式煤气柜的实际情况,采取现场调查、安全系统分析,制订切实可行的措施,顺利完成施工任务。     

粉煤灰改性吸附材料处理沥青烟气

分析了粉煤灰改性后的物质基础 ,采用吸附法 ,利用改性粉煤灰作为吸附剂对沥青烟气进行处理 ,通过实验研究得到一定的运行参数 ,为沥青烟气的处理提供了理论依据     

固相微萃取气相色谱法测定水样中的苯胺、吡啶

应用PDMS/DVB固相微萃取探头,结合GC/FID测定水中的苯胺、吡啶.优化了萃取温度、萃取平衡时间、pH等条件.该方法对苯胺和吡啶的检测限分别为0.050、0.065 mg/L,相对标准偏差6.44%～8.67%,具有快速、准确和方便等优点.