One-dimensional Steady-state Model for Gas Pressure Distribution in Municipal Solid Waste Landfills

Gas pressure distribution in landfills is of great importance to control hazards and improve recovery of landfill gas. An one-dimensional steady-state model and its solving approach are presented for gas pressure distribution in layered waste landfills. The model can be used to investigate the gas pressure distribution of the landfill with horizontal gas collection layers having specified pressure or flux. The influences of layered properties, horizontal permeable layer under final cover and horizontal gas collection layers and bottom leachate drainage systems dually serving as gas collection layers on gas pressure distribution are investigated. The results of parameter analyses using the presented model show that the assumption that homogenizations of gas generation rate and gas permeability through a landfill considerably overestimate gas pressure in landfill; horizontal permeable layer under final cover and horizontal gas collection layers can effectively reduce gas pressure in landfills; the bottom leachate drainage systems dually serving as gas collection layers can significantly reduce the gas pressure in the lower portion of landfills. The presented model provides a useful tool in the designing of landfill gas collection systems, such as, the positions and spacing of horizontal gas collection layers and pump section.     

Experimental analysis of matrix shrinkage’s influence on mechanical permeability of gas filled coal

Based on the coal seam of Zhao zhuang coal mine and Si he coal mine belong to Jin cheng anthracite Mining Group in Shanxi province, by using the self developed three axial servo controlled seepage equipment for hot fluid solid coupling of coal containing methane, parallel experiments for permeability of helium and methane under different gas pressures are carried out to quantitatively study the influence of Klinkenberg effects on the permeability of coal. Meanwhile, the problem of permeability decreasing caused by fluid pressure decreasing and gas desorption is eliminated by controlling the effective stress. The results show thatthe Klinkenberg effect is obvious under low gas pressure. With the increase of gas pressure, the permeability of coal decreases at first and then increases. The inflection points of gas pressure for Klinkenberg effect are about 0.9 MPa both for coal samples in Zhao zhuang coal mine and Si he coal mine. When the effective stress is constant, with the increase of gas pressure, the permeability increment caused by Klinkenberg effect decreases, while permeability increment caused by coal matrix shrinkage increases. Coal matrix shrinkage has a close relationship with the mechanical properties of coal rock mass. For the coal sample with a poor mechanical property, coal matrix shrinkage is more obvious.     

Local and global aspects of the bottom nepheloid layers in the world ocean

The bottom 1 km of the ocean is appreciably more turbid than the two or more km above it. This bottom nepheloid layer has been mapped principally by nephelometers that are most sensitive to particles ⪅2 μm in diameter. However, the layers contain larger aggregated particles which play an important role in sedimentation. The thickness of the nepheloid layer is much greater than the height above the bed to which turbulent mixing occurs, a fact explained by lateral transport of turbid mixed layers that have detached from the bottom. The overall upwards decline in turbidity is accounted for by the layers higher above the bed having come farther and being on average older than those lower down. The most intense nepheloid layers are found in areas of strong western boundary currents and in regions where the bottom current regime is thought to be highly variable due to penetration of eddy energy from the surface. Areas under the Gulf Stream and in the Argentine basin are examples. Review of the distribution and characteristics of nepheloid layers examines features contributing critically to these hypotheses. An important contributing factor to the depth distribution of turbidity is that the ratio of water volumes to bed areas in contact with them is eight times higher for water between 4 and 5 km than that between 2 to 3 km.     

Hydrogeological Investigation and Prediction of Water Yield of Jigong Mountain Tunnel

Jigong Mountain Tunnel is a controlled project in the reconstruction of Xinyang-Chenjiahe section.Based on hydrogeological investigation,tunnel's hydrogeology character such as geological structure,development of surface water and underground water,recharge of surface water and groundwater is evaluated,and normal and maximum water yield are predicted in the way of groundwater runoff modulus.It has been shown that normal and maximum water yield are equal to 860 m3/d and 1 283 m3/d,so the whole tunnel is a poor water section,while the speculated are ebbing water ones.     

Study on the Factors Affecting Gas Permeability of Coal

In this paper,the permeability of coal from Nantong colliery is studied in a labo-ratory. The effects of desorbed gas temperature and water content on gas permeability were investi-gated. The results of experiments indieatd that decreasing gas pressure without desorption , the permeability of coal decreases, However, below the desorption pressure, the permeability of coal formethane increases, The reaults suggest that the logarithm of permeability of coal is a linear functionof the temperature and the permeability of coal saturated with water is lass than the permeability ofdry coal; with the increase of water content, the permeability of coal for methane is increasing.     

System of the Geothermal Water in the Nanwenquan Anticline

In order to exploit and protect the geothermal water scientifically, the chemistry and isotope of geothermal water are studied in Nanwenquan anticline. It is show that the geothermal water comes from atmosphere precipitation in the north of Tongluoxia anticline, in which the Tongluoxia anticline and Nanwenquan anticline are whole geothermal water system. The geothermal water flows from north to south. The geothermal water has hydraulic contact from north to south, from the western limb to eastern limb. The geothermal waters in Nanwenquan anticline are whole geothermal water system. Every exploration of the geothermal water in Nanwenquan anticline should layout. So it can avoid that the yield is higher than pondage, and the geothermal water source environment is destroyed. The study provides theoretical gist for exploiting and utilizing rationally and protecting geothermal water resource effectively.     

Pressure Sweep Adsorption Processes for the Concentration of Methane from Coal-bed Gas Extracted

The coal-bed gas was usually extracted from mine in order to avoid coal gas outburst.The Methane(CH4),a main component in coal-bed gas,is a kind of excellent gas fuel and raw material for chemical industry.China is very rich in the resource of coal bed gas,however,most of the coal bed gas extracted from mine is wasted because of the too low concentration of methane. Pressure sweep adsorption(PSA) technique is noticeable among the methods for the concentration of methane from coal-bed gas.However,there are a few studies about this field.Studies on the pressure sweep adsorption(PSA) process for the separation of CH4/N2 using actived carbon as adsorbent are summarized.The thermodynamic relationships and kinetic processes and the influence of the operate parameters on the concentration of methane are investigated.These results have a direct application in coal-bed gas.Some suggestions for the problems need to be solved in PSA process for the separation of methane are also proposed.     

Multi-field coupling effect on coalbed methane seepage characteristics and numerical simulation

This paper studies the seepage of coal samples under the influence of each single factor, the axial stress, confining pressure, gas pressure, and temperature by experiments. It uses Ansys12.0 to numerically simulate the law of coalbed methane seepage, coal deformation, pore pressure, the distribution of flow field under the influence of each single field and multi-field coupled. The numerical simulation show that the result of numerical simulation of gas seepage law in the coal under each single fields is basically the same as the experimental result. The curve of gas seepage and average effective stress under the condition of multi-field coupled is negative exponential relationship. Stress influenced the deformation of the specimen is greater than the seepage field. The axial stress on the deformation of the specimen is greater than confining presses The influence on the flow field by confining pressure is greater than axial stress, the influence of axial stress on the pore pressure is greater than confining pressure, pore-pressure under the action of multi-field is bigger than pro-pressure under each single field. To study the seepage law of coalbed methane, it should consider the influence of gas-solid-heat at the same time.     

Experimental analysis of coal bed methane desorption and seepage under sonic vibrating of cavitation water jets

A way to enhance coal bed methane desorption and seepage by sonic vibrating of cavitataion water jets is proposed because the gas coal seams have the intrinsic properties of micro-porosity, low permeability and high adsorption. The mechanisms of how the sonic vibrating effects promote methane desorption and seepage are analyzed, and the contrast experiments of methane desorption and seepage under sonic vibrating effects are also provided. The results show: when the cavitation number is 0.020 0, under sonic vibrating effects, the volume of coal bed methane desorption increases by 36.9%, and the time for coal bed methane desorption reduces by 19.6%. The speed of coal seams methane seepage is significantly increased by 35.3% and arrives at 0.383 3 ml/s.     

松嫩平原地下水氮污染空间变异性及健康风险评价

为探明松嫩平原地下水污染现状及氮污染影响,利用地统计学软件分析了“三氮”(硝态氮、亚硝态氮和铵态氮)含量的特征,采用ArcGIS绘制了地下水硝态氮的变异函数图和空间分布图,并应用健康风险评价模型进行了氮污染对人体的潜在健康风险评价。上述研究表明,该区地下水污染物以“三氮”最为突出,其中硝态氮污染最重,变异系数为1.686,属于强变异,含量分布与二阶球状模型拟合最好,块金值和基底效应分别为2.423和0.575,其含量的空间异质性是结构性因素及随机性因素共同造成的,随机性因素稍强;硝态氮污染高风险区占总面积的88.78%,主要分布在东中部高平原区,这一区域大部分为III类水,对人体健康存在较高的风险,应引起关注。     

水稻植株对稻田甲烷排放的影响及其生物学机理研究进展

稻田是主要的农业甲烷排放源之一,对全球温室气体排放有着重要影响。稻田甲烷排放包括土壤产甲烷菌的产甲烷过程、好氧甲烷氧化菌的氧化甲烷过程及甲烷通过水稻植株体、土壤溶液中冒气泡及分子扩散三种运输途径的排放过程,水稻植株地上部和根系影响着稻田甲烷排放。本文简要介绍了稻田甲烷的产生、氧化和运输排放过程,综述了水稻根系特征（形态、通气组织、分泌物、根系泌氧）、地上部特征（株高、分蘖数、生物量和同化物分配）、水肥管理措施对稻田甲烷排放的影响及内在机理。本文也讨论了今后稻田甲烷排放的主要研究方向,并认为高产与减排的协同应是一个重要切入点。     

玛纳斯河流域沙漠与绿洲过渡带土壤水盐变化特征与规律

土壤盐碱化防治是新疆地区农业乃至社会经济发展的重要任务。在新疆古尔班通古特沙漠南缘选取了两个耕地土壤剖面和一个丘间地原生土壤剖面进行调查,室内测量其土壤粒径、容重、含水率和含盐量,探讨了原生盐碱荒地及开垦农田水盐变化特征与规律,以便为该地区防治盐碱化提供必要的科学依据。调查分析结果表明：（1）土层物理性质的差异对土壤水盐分布特征有较为明显的影响,粘粒及粉粒较多的土层积盐现象更为明显;（2）土层的结构异质性对水分盐分有阻滞作用,导致土壤中存在盐分堆积层;（3）灌溉水导致土体淋溶强度增大,这虽能降低土体中的盐分却增加地下水矿化的风险。建议该地区土壤盐碱化防治应因土层异质性而设置相应的排水措施,灌排结合以达到土壤盐碱化防治乃至保护地下水的目的。     

Mechanism and application of protection againstoutburst for abrasive water jet slotting technology

Aiming at the status quote of long time for methane extraction and slow speed for laneway excavating in coal seams of Liziya south 2JHJ well, abrasive water jet slotting technology is adopted to improve the methane desorption and increase excavating speed in semi-coal laneway. Through analyzing damage model and protection against outburst mechanism, the process of Coal-Rock Mass being cut and fractured is studied. Through lab test on abrasive water jet cutting coal-bed gangue, a new abrasive water jet cutting device is successfully designed and made and all parameters are determined. It is showed that abrasive water jet can cut through a coal-bed gangue with thickness 60~80 mm and uniaxial compressive strength 62 MPa. After cutting coal seams by abrasive water jet, the surface area for methane is enlarged and then coal seams pressure fell rapidly. Therefore the permeability and desorption of coal seams are greatly increased. The results are as follows: the average productivity of single-hole was enhanced by 2.83 times.     

Economic Benefit Analysis on the Exploitation and Utilization Coal bed Methane

The gas accident in Coal Mine is an important safe hidden trouble.The notion on the prevention and cure of gas accident should be changed.Coal gas is a kind of deleterious gas,but it is a clean energy resource.The actualities of coal bed methane resources and its use in our country are reviewed.The foreground for the use of coal bed methane is analyszed.The economic benefit of coal bed methane utilization is evaluated by the Net Present Value(NPV) and the Internal Rate of Return(IRR)method.The results are shown that the utilization of the coal bed methane can decrease the gas accident,save energy source,reduce the environmental pollution,and have remarkable economic benefit.     

Fathering Benefit Research of Slopng Cultivated Land Erosion in Three Gorges Reservior

To prevent and reduce the threats to the sustainable development of agriculture of Three Gorge Reservoir caused by the serious soil erosion and degradation of sloping cultivated land, seeking the means of suitable utilization of sloping cultivated land is very necessary. Due to the different cultivating modes make great influence to the lost of water, soil, and fertility, aiming at the utilization status and existing problems of sloping cultivated land in Three Gorge Reservoir, the characteristics and respective adaptability of different cultivating modes are analyzed using the relation between different cultivating modes and the water and soil lost of sloping cultivated land. And the research methods of lost of water, soil, and fertility of sloping cultivated land in different cultivating modes are summarized and the perspective of the development, utilization and protection of sloping cultivated land are given as well.     

Calculation of Fatigue Reliable Life of Natural Gas Pipeline

Various defects and cracks may be produced in the welding process in natural gas pipeline.Under variable pressure of natural gas,the cracks will be propagated it may lead to break and invalidity.The effect of internal surface cracks are more serious.It has been researched that the propagation along radial direction of internel surface cracks in the natural gas pipeline.The fatig life of pipeline has been calculated.On the other hand,considering the size of cracks, pressure of gas and character of material are random variable,and by using reliability method,the fatig reliable life of pipeline has been determined.This method has some practical value in design, working and overhaul of pipeline.     

Analysis on rock cross-cut coal uncovering using high pressure water jet slotting in close distance seam group

Safe production and procedures at the driving face are restricted in mines of Guizhou province by the long periods required for rock cross-cut coal uncovering in high gas coal seam group. A new method is proposed to solve this problem using high pressure water jet slotting in penetration boreholes. This is proposed to increase the gas desorption rate and reduce drilling hole, which will shorten the cycle of rock cross-cut coal uncovering. Numerical simulation is used to compare the pressure relief effects of different slotting methods in penetration boreholes. The results show that the pressure relief effect of slotting all coal seams is more ideal. Field application indicates that high pressure water jet slotting has good effect of the pressure relief in coal seam group. The drilling number is reduced by 30, the drilling length is shortened by 610 m and the standard time of gas pre-pumping decreases by 39 days.     

基于LS-SVM逆系统的焦炉集气管压力系统内模控制

焦炉集气管压力是炼焦生产过程中重要的工艺参数,其值是否稳定,直接影响到煤气质量、焦炉寿命、焦炭质量和生产环境。针对焦炉集气管压力系统是一个强干扰、非线性和多变量耦合的复杂系统,采用LS-SVM辨识出焦炉集气管压力系统的逆系统模型,并将其串联在原系统之前,运用逆系统的方法将集气管压力系统解耦成2个相互独立的单输入单输出伪线性子系统。同时,对解耦后的系统采用非线性内模控制策略以保证系统的鲁棒性和稳定性。仿真和应用结果表明该控制策略的解耦控制效果较好,提高了系统的快速调节能力和跟踪精度,而且增强了系统的鲁棒性,可以保证焦炉集气管压力稳定在现场工艺要求的范围内。     

河北棉田复合种植模式水分利用比较研究

河北南部植棉区受麦玉两熟高耗水农作模式的影响,地下水位亏缺,生态恶化。受此影响,当地棉田在保证高效的同时也存在着节水或提高水分利用效率的需求。通过设计新型的棉田复合种植模式,从水分效益与经济效益两个方面对各种种植模式的水分利用情况进行比较分析,探讨不同种植体系的耗水规律,筛选出水分经济利用效率高、实现农田水分生态修复的棉花种植模式。研究结果表明：设计的5种种植模式中辣椒/棉花间作的水分经济利用效率（EWUE）最高,达60.29元/(mm?hm2),其次为马铃薯/棉花间作,因此,辣椒/棉花间作与马铃薯/棉花间作是该区域具有推广可行性的两种棉田种植模式。5种棉田种植模式能够维持田间水分的周年平衡,其中辣椒/棉花间作能够对地下水资源起到较好的生态补偿作用。黑麦-棉花轮作模式和苜蓿/棉花间作模式在利用深层水分方面更具比较优势。     

Applications of SOM Neural Network in Multiple-faults Diagnosis of Turbogenerator Set

The turbogenerator vibration faults have the character of variety. Many faults often occur synchronously. The traditional BP neural network can diagnose the single fault effectively. If we diagnose the multiple faults by using the BP neural network, we must train all samples of multiple faults, which is will increase the number of training samples and the burden of learning greatly. So the diagnosis can not be performed easily. This paper introduces a method based on SOM neural network, which is studied by using the single sample and diagnosing the multiple faults according to the position of output nerve cell. By analyzing the examples, the method is proved to be available for diagnosing the multiple faults of Turbogenerator set.