煤矿乏风（通风瓦斯）排放及利用现状

介绍了目前国内外对乏风的治理和利用现状,并简要阐述了胜动集团煤矿乏风CH4氧化技术。     

立式乏风氧化装置的开发与应用

介绍了立式乏风氧化装置的主要构成、技术特点及应用情况.     

矿井乏风逆流式氧化技术阻力实验研究

本文介绍了矿井乏风氧化技术的两种方案(TFRR和CFRR)及当前的国内外研究进展情况。介绍了抽气余热锅炉式热逆流氧化技术的实验平台及冷态阻力特性研究;利用所得实验数据回归冷态阻力无量纲关系式,对冷态关系式进行温度修正,对比实测值和计算值,表明冷态实验结果能用于热态实验设备选型。     

煤矿瓦斯(乏风)氧化利用方式及效益分析

介绍了煤矿瓦斯(乏风)氧化的必要性,瓦斯(乏风)氧化的基本原理和工艺特点。根据煤矿现场对热量需求不同情况,论述了氧化装置在煤矿的四种用途下的经济及环境效益,并分析煤矿瓦斯(乏风)氧化降低当地或附近地区大气粉尘和缓解大气雾霾天气的作用。     

煤矿通风中的瓦斯处理技术研究

通过对煤矿通风中应用瓦斯处理技术的情况进行分析,以期更好地满足煤矿开采需求,减少瓦斯灾害事故的发生,同时提升瓦斯利用率。     

低温度乏风直接利用供热系统在新建煤矿的应用

新建煤矿生产前期乏风温度较低,矿井水水量很少无法利用,怎么解决冬季供热问题成为当务之急,低温度乏风如何利用成了研究的主要内容。以甘肃某新建煤矿为例,利用低温度乏风直接利用系统可解决生产前期大部分供热负荷需求,同时对该系统与燃煤锅炉进行运行费用对比分析,结果显示低温度乏风直接利用系统具有节能环保,无任何污染物排放的优势。     

煤矿井下通风瓦斯防治技术

对于煤矿井下通风来讲,其指的是把空气输送到矿井下,在提高矿井下氧气浓度同时,借助新鲜的空气冲淡,排出矿井内的有毒、有害气体,进而保证井下作业的安全。简要探讨了瓦斯爆炸的因素及危害,并以霍州煤电李雅庄煤矿矿井为例,提出相应的井下通风瓦斯防治措施,目的在于提高矿井的安全性能。     

煤矿瓦斯抽采技术研究及应用探究

以煤矿瓦斯抽采技术为研究对象,对煤矿瓦斯抽采技术的基本理论和抽采方法进行分析,对实际生产中煤矿瓦斯抽采技术所遇到的问题以及煤矿瓦斯抽采技术应用中存在的相关问题进行分析,并对煤矿瓦斯抽采技术的应用进行探究.     

煤矿瓦斯输运技术研究

矿井开采出的瓦斯气体如何进行输运是瓦斯利用的关键,因此,对煤矿瓦斯输运方式进行研究十分必要。瓦斯输运现有的4种主要方式(短距离管道输运、长距离管道输运、压缩输运、液化输运)分别进行了阐述,并对一种新兴的水合物法瓦斯输运方式进行了探讨。通过对这些输运方式的分析和研究,以针对不同环境条件,找到最佳的输运方式,为工程实践提供一定理论指导。     

浅谈煤矿瓦斯抽采技术

煤矿瓦斯是威胁煤矿安全生产的重要因素之一。为了保障矿工生命安全和提高煤矿经济效益,煤矿开采过程中需要科学合理地应用瓦斯抽采技术。对煤矿瓦斯抽采技术进行了分析,旨在为瓦斯抽采技术的科学有效应用提供参考和指导,从而为煤矿安全生产提供可靠保障。研究发现,地质条件、煤炭开采方式和瓦斯抽采设备是影响瓦斯抽采效果的重要因素,需要在瓦斯抽采设计和布置过程中综合考虑。通过合理布置瓦斯抽采井和瓦斯抽放孔,有效控制瓦斯的积聚和排放,可以降低发生煤矿瓦斯事故的风险。     

Hydrogen production through partial oxidation of methane in a new reactor configuration

Performance of the side feeding (SF) air injection in the process of partial oxidation of methane (POM) has been investigated by means of developing a one-dimensional steady-state non-isothermal model. A fixed bed reactor (FBR), a one-side feeding reactor (One-SF), and a membrane reactor (MR) has been compared for the conversion of methane, selectivity of hydrogen and reactor temperature. The results of the model revealed that the One-SF can operate within FBR and MR, and increasing the number of air injections of SF could achieve to the performance of the MR. The performance of the two to five-SF was studied according to the hydrogen selectivity, methane conversion, temperature profile and H₂/CH₄ ratio. It was observed that increasing the number of injections up to the three, increased the selectivity of hydrogen from 0.496 to 0.530 and decreased the outlet temperature from 1269 K to 1078 K. These results lead to creating of a process with controllable operating temperature and enhancing the selectivity of hydrogen. Consequently, decreasing the problems of high operating temperature in FBR and reduction of the process cost compared with MR.     

Hydrogen production by partial oxidation of methane: Modeling and simulation

A one-dimensional non-isothermal model for oxygen permeable membrane reactor has been developed to simulate the partial oxidation of methane to produce hydrogen. The performance of two fixed bed reactors (FBRs) viz. one with pure O₂ in feed (FBR1), other with air in feed (FBR2), and a membrane reactor (MR) having air in non-reaction side have been studied at various feed conditions and inlet temperatures in order to investigate the effect of these parameters on conversion of methane and yield of hydrogen. The fixed bed reactor with pure O₂ in feed has been found to provide better performance as compared to fixed bed reactor with air and membrane reactor.     

Fixed beds of Rh/Al2O3-based catalysts for syngas production in methane SCT-CPO reactors

The present experimental work deals with methane short contact time (SCT) CPO in a fixed bed reactor considering CH₄ conversion and H₂ and CO selectivity in a wide range of weight hourly space velocity (WHSV). Two different Rh/Al₂O₃-based catalysts both loaded with 0.5% by weight of Rh were developed: one catalyst carrying Rh on the external support surface (Egg-Shell configuration), and the other one with Rh embedded into the porous support (Egg-Yolk configuration). The goal was the design of the optimal fixed bed structure (not only considering beds made of egg-shell or egg-yolk catalysts alone, but also their various combinations), able to either attain the best performance or maintain a reaction temperature along the bed without excessive variations with WHSV. The highest CH₄ conversion (>90%) and H₂ selectivity (>98%), moreover stable despite the WHSV variation of about 3.6 times, and reactor working temperature with not too large variations (maximum of about 16%) by increasing WHSV were obtained with the fixed bed of Egg-Yolk catalyst alone. Instead, the fixed bed of Egg-Shell catalyst alone showed the worst performance: CH₄ conversion and H₂ selectivity were lower of about 15% and 10%, respectively, and decreasing with the increase of WHSV; on the contrary, the CO selectivity remained practically the same, only a slightly decrease being observed. Suitable combinations of the two catalysts in the fixed bed produced intermediate performance between those of the catalysts alone. The different performance of the two catalyst types was probably due to the different structure of the particles and to the Rh position on the carrier itself. Finally, thermal and performance durability tests up to 16 working hours showed that the Egg-Yolk catalyst employed alone in the fixed bed was able to maintain the CH₄ partial oxidation activity with practically disregardable decrease.     

Modeling of fluidized bed membrane reactors for hydrogen production from steam methane reforming with Aspen Plus

Hydrogen production via steam methane reforming with in situ hydrogen separation in fluidized bed membrane reactors was simulated with Aspen Plus. The fluidized bed membrane reactor was divided into several successive steam methane sub-reformers and membrane sub-separators. The Gibbs minimum free energy sub-model in Aspen Plus was employed to simulate the steam methane reforming process in the sub-reformers. A FORTRAN sub-routine was integrated into Aspen Plus to simulate hydrogen permeation through membranes in the sub-separator based on Sieverts' law. Model predictions show satisfactory agreement with experimental data in the literature. The influences of reactor pressure, temperature, steam-to-carbon ratio, and permeate side hydrogen partial pressure on reactor performances were investigated with the model. Extracting hydrogen in situ is shown to shift the equilibrium of steam methane reactions forward, removing the thermodynamic bottleneck, and improving hydrogen yield while neutralizing, or even reversing, the adverse effect of pressure.     

Modelling the hydrodynamics and kinetics of methane decomposition in catalytic liquid metal bubble reactors for hydrogen production

Bubble reactors using molten metal alloys (e.g, nickel-bismuth and copper-bismuth) with strong catalytic activity for methane decomposition are an emerging technology to lower the carbon intensity of hydrogen production. Methane decomposition occurs non-catalytically inside the bubbles and catalytically at the gas-liquid interface. The reactor performance is therefore affected by the hydrodynamics of bubble flow in molten metal, which determines the evolution of the bubble size distribution and of the gas holdup along the reactor height. A reactor model is first developed to rigorously account for the coupling of hydrodynamics with catalytic and non-catalytic reaction kinetics. The model is then validated with previously reported experimental data on methane decomposition at several temperatures in bubble columns containing a molten nickel-bismuth alloy. Next, the model is applied to optimize the design of multitubular catalytic bubble reactors at industrial scales. This involves minimizing the total liquid metal volume for various tube diameters, melt temperatures, and percent methane conversions at a specified hydrogen production rate. For example, an optimized reactor consisting of 891 tubes, each measuring 0.10 m in diameter and 2.11 m in height, filled with molten Ni_0·27Bi_0.73 at 1050 °C and fed with pure methane at 17.8 bar, may produce 10,000 Nm³.h^?1 of hydrogen with a methane conversion of 80% and a pressure drop of 1.6 bar. The tubes could be heated in a fired heater by burning either a fraction of the produced hydrogen, which would prevent CO₂ generation, or other less expensive fuels.     

Modeling of the optimum tilt of a solar chimney for maximum air flow

The aim of this work is to develop a mathematical model to determine the tilt that maximizes natural air flow inside a solar chimney using daily solar irradiance data on a horizontal plane at a site. The model starts by calculating the hourly solar irradiation components (direct, diffuse, ground-reflected) absorbed by the solar chimney of varying tilt and height for a given time (day of the year, hour) and place (latitude). In doing so it computes the transmittance and absorbance of the glazing for the various solar irradiation components and for various tilts. The model predicts the temperature and velocity of the air inside the chimney as well as the temperatures of the glazing and the black painted absorber. Comparisons of the model predictions with CFD calculations delineate the usefulness of the model. In addition, there is a good agreement between theoretical predictions and experiments performed with a 1 m long solar chimney at different tilt positions.     

自然通风建筑内空气流动和污染物扩散的数值模拟

数值模拟了单体自然通风建筑模型内的空气流动和污染物扩散,考察了紊流施密特数Sct对污染物模拟值的影响。结果表明,选取的3种紊流模型对时均流速和紊动能的模拟值和风洞试验值基本一致,标准k-ε模型与realizable k-ε模型模拟的流场较相似,其浓度场结果也基本相同,当Sct为0.8～1.0时,模拟值和试验值吻合得最好。由于RNG k-ε模型对地面污染源附近的时均流动模拟不准确,导致其浓度模拟值和试验值相差较大,因此,选取合理的Sct时,应基于准确的流动模拟,而不能仅考察浓度模拟值和试验值的吻合程度。     

Experimental study for comparison of thermal comfort and air age between two combined ventilation systems with chilled ceiling considering occupant density

Due to the global spread of diseases and epidemics, the need to maintain a clean indoor atmosphere has received increasing attention in recent years. Therefore, there will be a need to clearly estimate and define the areas that affect human exposure to pollutants, taking into account the occupied density, which is the primary importance of this research. The capacity of the chilled ceiling combined with mixing ventilation and personal ventilation systems has been studied and compared to the chilled ceiling with mixing ventilation in terms of mean air age, temperature distribution, CO₂ concentration, and thermal efficiency, with the best flow rate of the proposed system considering the occupied density in a thermally insulated office room experimentally in the climate of Iraq (Hilla, a hot and dry climate). Twelve tests were performed for four different cooling loads with cooled ceilings (0%, 0.25%, 50%, and 80%), at a constant supply air flow rate with two PV airflow modifiers for three cases. As the cooling load treated by a chilled ceiling increased, the average air temperature increased with height in all cases. The lowest values of average air age appeared in the occupied area in the case of a chilled ceiling with mixing ventilation. This study shows that the chilled ceiling combined with a mixing ventilation and personal ventilation system with a flow rate of 7.5 L/s provides thermal comfort and higher air quality in the occupied area. based on the values of air exchange efficiency and occupants’ air exchange efficiency. As a result, a flow rate of 7.5 L/s is the best option for protecting occupants from direct pollution in the breathing zone and in the surrounding microclimate, because the lower the ventilation rate, the less air is changed for occupants.     

A two-dimensional mathematical model for the catalytic steam reforming of methane in both conventional fixed-bed and fixed-bed membrane reactors for the Production of hydrogen

A modelling and simulation study of catalytic steam reforming of methane is presented in this paper. A two-dimensional pseudo-heterogeneous model is developed to simulate a conventional fixed-bed reactor (FBR) as well as a fixed-bed membrane reactor (FBMR) with sweep gas added in both co-current modes for the two reactor configurations. The developed model is based on mass and energy balance equations for the catalyst phase and the gas phase in both FBR and FBMR reactors. Firstly, a study is done for describing that the temperature profiles of gaseous and solid phases reach to stable state as well as the component distributions in the two FBR and FBMR reactors. The model covers the aspect of the partial pressure of hydrogen in the membrane reactor with the permeation of hydrogen across a Pd-based membrane. The conversion of methane is significantly enhanced by the partial removal of hydrogen as from the shell side as a result of diffusion through the Pd-based membrane. Simulation results demonstrated that methane conversion of 97.21% can be achieved in FBR at operating temperature of 1250 K relative to methane conversion of 99.79% to 923 K in FBMR. The yield of hydrogen achieved to level from 2.154 in FBR at operating temperature of 1250 K while the yield of hydrogen reached to level from 3.731 with a thickness from 1.7 μm in FBMR reactor.     

Measurements of minimum ignition energy in premixed laminar methane/air flow by using laser induced spark

Reducing engine pollutant emissions and fuel consumption is an important challenge. Lean-burning engines are a promising development; however, such engines require high-energy ignition systems for typical working conditions (equivalence ratio, Φ < 0.7). Laser-induced ignition is envisaged as a way to obtain high-energy ignition as a result of progress that has been made in laser beam technology in terms of stability, size, and energy. This study investigated the minimum energy necessary to ignite a laminar premixed methane air mixture experimentally. A parametrical study was performed to characterize the effects of the flow velocity, equivalence ratio, and lens focal length on the minimum energy required for ignition. Experiments were conducted using a premixed laminar CH₄/air burner. Laser-induced breakdown was achieved by focusing a 532-nm nanosecond pulse from a Q-switched Nd:YAG laser with an anti-reflection-coated lens. Mixture ignition and the early stages of flame propagation were studied using a high speed Schlieren technique. Despite the stochastic characteristic of the laser breakdown phenomena, good reproducibility in the minimum energy required for the ignition measurements was observed. The cases in which the CH₄/Air mixture flow ignites are defined as those with a laminar flame front propagation visible in the Schlieren images 10 ms after the energy deposition. The same minimum ignition energy (MIE) versus equivalence ratio (Φ) type of curves were obtained with a laser-induced spark and with a spark plug. Due to the threshold of energy required to obtain breakdown and the stochastic character of the energy absorption by the spark, a constant value was obtained (corresponding to the breakdown threshold) when the minimum ignition energy was lower than the breakdown threshold. As already noticed by several authors, MIE values higher than those observed using spark plugs were obtained. However, these differences tended to disappear at the lean and rich fuel limits.