我国农村推广秸秆类生物质气化集中供气技术探讨

从提高秸秆类生物质利用效率与利用价值、提高农民生活质量与生活品位、减少污染、充分利用可再生能源资源和延缓不可再生能源资源的持续利用等,阐明推广应用秸秆类生物质气化集中供气技术的重要意义;介绍气化基本原理与工艺流程,秸秆类生物质粉碎后通过干燥、裂解反应、氧化反应和还原反应,即可完成气化全过程;气化工程由燃气发生炉机组、储气柜、输气管网和用户燃气设备4部分组成;秸秆类生物质燃气与城市管道煤气具有共同的特点。     

西气东输工程的环境协同效应研究

协同效应研究是气候变化政策研究的新领域,也是非常重要的领域.西气东输工程的主要目的是为我国中东部地区输送丰富的天然气资源,但其实施同时也有助于减少东部地区大气污染物排放,改善大气质量.利用较成熟的中国区域环境与经济综合评价模型(AIM-LOCAL/China模型),从用气项目的SO₂和CO₂排放的常规情景(BAU)和利用天然气后的情景(NGS)两方面进行了量化比较,分析西气东输工程的环境协同效应.研究发现:在用气项目的范围内,NGS情景下的SO₂排放相比BAU情景明显减少,同时CO₂等温室气体排放也大幅减少.2003-2020年,累计可以减排约312×104 t SO₂和3 475×104 t CO₂,分别比BAU情景减排40.5%和17.9%.从4个用气部门来看,不论是SO₂还是CO₂,电力部门用气项目的减排量都占突出位置.      

Reduction of CO2 emission by optimally tracking a pre-defined target

The recent global financial crisis has highlighted the need for balanced and efficient investments in the reduction of the greenhouse effect caused by emissions of CO₂ on a global scale. In a previous paper, the authors proposed a mathematical model describing the dynamic relation of CO₂ emission with investment in reforestation and clean technology. An efficient allocation of resources to reduce the greenhouse effect has also been proposed. Here, this model is used to provide estimates of the investments needed in land reforestation and in the adoption of clean technologies for an optimum emission and abatement of CO₂, for the period of 1996–2014. The required investments are computed to minimize deviations with respect to the emission targets proposed in the Kyoto Protocol for European Countries. The emission target can be achieved by 2014 with investments in reforestation peaking in 2004, and a reduction of the expected GDP of 42%, relative to 2006. Investments in clean technology should increase between 2008 and 2010 with maximum transfer figures around 70 million American dollars. Total (cumulative) costs are, however, relatively high depending on the price of carbon abatement and the rate at which the expected CO₂ concentration in the atmosphere should be reduced. Results highlight the advantages for policy makers to be able to manage investments in climate policy more efficiently, controlling optimum transfers based on a portfolio of actions that tracks a pre-defined CO₂ concentration target.     

供配电系统对煤气系统安全的影响及对策

针对几起煤气系统中供配电系统的事故案例 ,分析了供配电系统故障对煤气系统的危害 ,提出了对策与建议。     

水、氮控制对短花针茅草原气体交换的影响

随着对气候变化日趋关注,人们对生态系统气体交换及其主要影响因素进行了大量研究。短花针茅草原作为荒漠草原的典型代表,是亚洲特有的一种草原类型,是最干旱的草原类型,生态环境异常严酷,系统极度脆弱,稳定性差,在自然和人为干扰下极易退化。以短花针茅（Stipa breviflora）草原为研究对象,通过控制降雨量以及氮素添加对生态系统气体交换进行监测,研究气体交换对降雨量和氮素添加的响应过程,揭示降雨量和氮素添加对生态系统气体交换的影响作用。该文在2012年自然条件下,采用自动CO2通量系统（Li-6400, Li-COR, Lincoln, NE, USA）野外测定短花针茅（Stipa breviflora）草原生态系统气体交换数据,比较研究了增雨施肥（WN）、增雨不施肥（W）、减雨施肥（RN）、减雨不施肥（R）、单独施肥（N）、自然状况（CK）条件下2012年气体交换变化规律。结果表明：整个生长季生态系统净 CO2交换（NEE）、总的生态系统生产力（GEP）、生态系统呼吸值（ER）都呈先升高后降低的趋势,并在生长旺盛期（8月）达到最大值。NEE在N、W处理下有升高,其他处理都降低。ER在N、WN处理下都有升高,其他处理都降低。GEP在W、N、WN处理下都有升高,其他处理都降低。NEE、ER、GEP都是在N处理中达到最大值。     

Accuracy improvement in evaluation of gas explosion overpressures in congestions with safety gaps

This paper reports a comparison of simulations and published data from experiments carried out by TNO Prins Maurits Laboratory on geometric configurations that involved safety gaps of various separation distances. The Computational Fluid Dynamics (CFD) based software – FLACS is utilized to conduct the numerical simulations. In the majority of cases, good agreement is found between the simulated results and those obtained by experiment in both the donor and acceptor modules. However, a large discrepancy in the overpressures in the acceptor module is seen when the size of the separation gap approaches one or two times of the module size. A Data-dump technique is used in this study to reset the turbulence length scale for these cases with different separation distances, five sets of explosion scenarios are then numerically simulated and the overpressures are compared with experimentally measured explosion overpressures. The overall results indicate that the software with the Data-dump technique is still an extremely effective tool when it comes to the evaluation of gas explosion overpressures in areas with large separation gaps.     

Experimental study on the suppression of gas explosion using the gas–solid suppressant of CO2/ABC powder

Gas explosion is the leading accident in underground coal mining in China. Using the self-improved 20 L spherical experimental system, the impacts of 8% CO₂, ABC powder at various concentrations and mixture of them on the suppression of mine gas explosion were investigated. The results indicate that cooperative synergism exists between ABC powder and CO₂. Their combination has a better effect than each of the two components acting alone, especially for the gas of larger concentration. When 0.25 g/L ABC powder was mixed with 8% CO₂, the explosion limits were reduced by about 55%, the time to reach the peak explosion pressure was prolonged 3.56 times on average. Meanwhile, the maximum explosion pressure declined on an average of 59.4% and the maximum explosion overpressure rising rate decreased on an average of 91.1%. A combination of 0.20 g/L ABC powder and 8% CO₂ completely suppressed 11% gas explosion. The explosion suppression mechanism of CO₂ and ABC powder were probed theoretically. CO₂ plays a key part in the whole explosion processes, and it can effectively suppress the forward reaction between gas and oxygen. While it is during the middle-later period of explosion processes that ABC powder plays a critical role. The particles decomposed from heated ABC powder such as nitrogen and phosphor will react with free radicals rapidly. Besides, atoms as N, P are capable of participating in chain reaction and reacting with active groups, significantly suppressing the gas explosion.     

The propagation speed of the cracks in coal body containing gas

The destabilization of coal body containing gas that is caused by the quick propagation of the cracks in coal body containing gas and the high pressure gas, which result into coal and gas outburst. Thus, according to the theory of brittleness rupture mechanics the propagation speed calculation formula of the cracks in coal body containing gas is derived under constant stress and the mechanism of the cracks propagation is analyzed. The propagation speed of the cracks in coal body containing gas is calculated by the experimental work. The research results show that gas pressure make the cracks propagation easier, which is consistent with the analysis result of the propagation speed calculation of the cracks. As well as the propagation speed of the cracks increase with the augment of gas pressure.     

Rapid regional outburst elimination technology in soft coal seam with soft roof and soft floor

In order to solve the problems in outburst elimination of coal seams with outburst potential, methods of field testing, theoretical analysis and numerical simulation are employed in this study. It is found that the horizontal stress concentration surrounding coal unloading boreholes is the primary cause of the coal and gas blowouts in the process of the coal unloading and permeability improvement with high-pressure water jet. The results indicate that low borehole density and inefficient drainage are the main reasons for the occurrence of high outburst indices in the effeteness validation of regional measures to control outbursts. Based on numerical modeling results and onsite parameter testing, reasonable parameters such as borehole density are determined, and hydraulic fracturing is applied to improve coal seam permeability and relieve stress levels so as to eliminate regional outburst potential. The effect is significant in the field application, coal and gas blowout during the coal unloading period with high-pressure water jet is reduced dramatically, and the roadway development rate is increased by 48%. It is demonstrated that the gas drainage combined with the hydraulic fracturing, coal unloading with high-pressure water jet is a practical and effective technique for rapid elimination of coal and gas outburst potential in roadway development.     

Experimental study on leak detection and location for gas pipeline based on acoustic method

The leak of gas pipelines can be detected and located by the acoustic method. The technologies of recognizing and extracting wave characteristics are summarized in details in this paper, which is to distinguish leaking and disturbing signals from time and frequency domain. A high-pressure and long distance leak test loop is designed and established by similarity analysis with field transmission pipelines. The acoustic signals collected by sensors are de-noised by wavelet transform to eliminate the background noises, and time-frequency analysis is used to analyze the characteristics of frequency domain. The conclusion can be drawn that most acoustic signals are concentrated on the ranges of 0-100 Hz. The acoustic signal recognition and extraction methods are verified and compared with others and it proves that the disturbing signals can be efficiently removed by the analysis of time and frequency domain, while the new characteristics of the accumulative value difference, mean value difference and peak value difference of signals in adjacent intervals can detect the leak effectively and decrease the false alarm rate significantly. The formula for leak location is modified with consideration of the influences of temperature and pressure. The positioning accuracy can be significantly improved with relative error between 0.01% and 1.37%.