Optimization strategy and procedure for coal bed methane separation

Coal bed methane （CBM） has a huge potential to be purified to relieve the shortage of natural gas meanwhile to weaken the greenhouse effect. This paper proposed an optimal design strategy for CBM to obtain an integrated process configuration consisting of three each single separation units, membrane, pressure swing absorption, and cryogenics. A superstructure model was established including all possible network configurations which were solved by MINLP. The design strategy optimized the separation unit configuration and operating conditions to satisfy the target of minimum total annual process cost. An example was presented for the separation of CH4/N2 mixtures in coal bed methane （CBM） treatment. The key operation parameters were also studied and they showed the influence to process configurations.

A continuous and high-efficiency process to separate coal bed methane with porous ZIF-8 slurry:Experimental study and mathematical modelling

Coal bed methane has been considered as an important energy resource.One major difficulty of purifying coal bed methane comes from the similar physical properties of CH_4 and N_2.The ZIF-8/water-glycol slurry was used as a medium to separate coal bed methane by fluidifying the solid adsorbent material.The sorption equilibrium experiment of binary mixture(CH_4/N_2)and slurry was conducted.The selectivity of CH_4 to N_2 is within the range of 2-6,which proved the feasibility of the slurry separation method.The modified Langmuir equation was used to describe the gas-slurry phase equilibrium behavior,and the calculated results were in good agreement with the experimental data.A continuous absorption-adsorption and desorption process on the separation of CH_4/N_2 in slurry is proposed and its mathematical model is also developed.Sensitivity analysis is conducted to determine the operation conditions and the energy performance of the proposed process was also evaluated.Feed gas contains 30 mol%of methane and the methane concentration in product gas is 95.46 mol%with the methane recovery ratio of 90.74%.The total energy consumption for per unit volume of product gas is determined as 1.846 kWh Nm^(-3).Experimental results and process simulation provide basic data for the design and operation of pilot and industrial plant.

A Non-linear Non-ideal Model of Simulated Moving Bed Chromatography for Chiral Separations

A non-linear non-ideal model,taking into account non-linear competitive isotherms,axial disperison,film mass transfer,intraparticle diffusion,and port periodic switching,was developed to simulate the dynamics of simulated moving bed chromatography(SMBC),The model equations were solved by a new efficient numerical technique of orthogonal collocation on finite elements with periodical movement of conceantration vector,The simulated SMBC performance is in accordance with the experimental results reported in the literature for separation of 1,1''''''''-bi-2-naphtol enantiomers using SMBC,This model is useful for design,operation ,optimization and scale-up of non-linear SMBC for chiral separations with significant non-ideal effects,especially for high solute concentration and small intraparticle diffusion coefficient or large chiral stationary phase particle.

Effect of bubbles addition on teetered bed separation

To improve the separation efficiency of a conventional Teetered Bed Separator(TBS) in beneficiation of fine coal with a wide size range,an Aeration TBS(A-TBS) was proposed in this investigation.The bubbles were introduced to A-TBS by a self-priming micro-bubble generator.This study theoretically analyzed the effect of bubbles on the difference in hindered settling terminal velocity between different density particles,investigated the impact of superficial water velocity(V_(SW)) and superficial gas velocity(V_(Sg)) on bed fluidization,and compared the performance of the TBS and A-TBS in treating 1-0.25 mm size fraction particles.The results show that the expansion degree of fluidized bed which was formed by different size particles or has different initial height,is increased by the introduction of bubbles.Compared with the TBS,at the same level of clean coal ash content,the A-TBS shows an increase in the combustible recovery of clean coal,ash content of tailings,and practical separation density by 5.26%,6.56%,and 0.088 g/cm3 respectively,while it shows a decrease in the probable error(E_p) and V_(SW) by 0.031 and 3.51 mm/s,respectively.The addition of bubbles at a proper amount not only improves the separation performance of TBS,but also reduces the upward water velocity.

Separation of phosphatidylcholine from soybean phospholipids by simulated moving bed

A simulated moving bed (SMB), equipped with eight silica-gel columns, was used to separate phosphatidylcholine (PC) from soybean phospholipids. The effects of flow rate in Sections 2 (Q2) and 3 (Q3), switching time, feed flow rate and feed concentration on the operating performance parameters: purity, recovery, productivity and desorbent consumption were studied. Operating conditions leading to more than 90% purity in both outlet streams have been identified, together with those achieving optimal performance. Regions leading to complete separation are observed and explained theoretically. As the mass-transfer effect was not considered, the triangle theory only gives initial guesses for the optimal operating conditions.

CFD-DEM simulation of fluid-solid flow of a tapered column separation bed

Research on recycling waste Printed Circuit Boards(PCB) is at the forefront of preventing environmental pollution and finding ways to recycle resources.The Tapered Column Separation Bed(TCSB) is invented aiming at disposing the problem that fine particles of waste printed circuit boards cannot be separated efficiently so as to obtain further insight about the underlying mechanisms and demonstrate the separation feasibility in the tapered column separation bed.In this work,a Computational Fluid Dynamics(CFD) coupled with Discrete Element Method(DEM) model for two-phase flow has been extended to simulate the fluid-solid flow in the tapered column separation bed.Its validity is demonstrated by its successful capturing the key features of particles' flow pattern,velocity,the pressure distribution,the axial position with time and axial force for particles with different densities.Simulation results show that the plastic particles and resin particles become overflow,while copper particles,iron particles and aluminum particles successively become underflow,with a discharge water flow rate of 1 m^3/h,an obliquity of 30°.The simulated results agree reasonably well with the experimental observation.Using this equipment to separate waste PCBs is feasible,theoretically.

Equivalent materials simulation experimental study on bed separations developing and mining subsidence in constant humidity and constant temperature conditions

A new experiment was made on the developing of bed separations and mining subsidence from Tangshan T2192 working face by equivalent materials simulation.The overburden deformation and the developing of bed separations with working face advanc- ing was simulated by a new model.The results show that the maximum value of bed separations moved forward gradually along with the working face advancing;the maxi- mum value of bed separations is 0.31～0.50 times of mining thickness.The key strata have a great influence upon surface subsidence during the overburden movement process.The mechanics parameters of new experiment are fitted with results in fields perfectly.

Mechanics Principle and Engineering Application of Split Layer and Bed Separation of Mining Overburden

To control land surface subsidence caused the underground mineral exploitation and the catastrophic phenomena such as serious damage of buildings, waterbodies, cultivated lands, railways, bridges caused by land subsidence, bed separation grouting technology of overburden is put forward. To provide theoretical support for the technology, the characteristics and the mechanics mechanism of mining overburden from layer-split to formation of bed separation are studied. On the basis of elastic sheet board theory, calculation formula of rock sheet deflection is presented, and the mechanics criteria of the separation formation and the calculation formula of bed separation volume are set up. Finally, the applications and technics of bed separation grout technology of mining overburden to control land subsidence in china are introduced.

陕西省煤矿典型水灾隐患特征及治理技术

陕西省煤炭资源丰富,2022年煤炭产量达7.46亿t,是我国主要产煤省份之一。由于全省煤矿区地质及水文地质条件差异明显,煤矿水灾类型多样,随着近年煤炭开采强度的增大,水灾事故时有发生,防治水形势较为严峻。以煤炭赋存条件为基础,系统总结区域水文地质结构特征,界定典型水灾类型及各类水灾影响区域分布,论述典型水灾的形成机理及特征,并提出了相应的防控技术。研究表明:(1)陕西省主要煤炭产区分为陕北、黄陇、渭北三大区,陕北侏罗纪煤田主要有顶板松散沙层水灾隐患、厚层砂岩水灾隐患、溃水溃沙灾害,局部区域分布有烧变岩对煤矿造成水灾隐患;黄陇煤田主要受顶板巨厚砂岩水灾隐患、离层溃水隐患、泥砂溃涌灾害隐患威胁;陕北石炭—二叠纪煤田和渭北煤田,主要受到煤层底板奥陶系灰岩水灾隐患威胁。(2)陕北侏罗系煤田顶板水灾隐患主要为顶板含水层受开采导水裂隙带扰动形成,导水裂隙波及砂岩含水层或松散沙层可形成持续大流量涌水,部分区域充水强度较大,在短时间水量较大超过排水系统能力时造成顶板水灾,在薄基岩区域垮落带直接导通松散沙层时可转变为溃水溃沙灾害,导水裂隙带影响到烧变岩富水区域时可形成瞬时水量大且持续的烧变岩水灾;黄陇煤田顶板巨厚砂岩含水层受采动导水裂隙带波及形成高强度持续涌水并可能形成顶板水灾,当含水层下部隔水层厚度较大时,可能形成离层溃水灾害,当近煤层顶板岩层松软遇水易崩解时可转变为泥砂溃涌灾害;陕北石炭—二叠纪煤田和渭北煤田,煤层开采底板扰动破坏带或断层等构造导通奥陶系灰岩含水层时,会引发极为严重的底板突水灾害,该类灾害具突发性强、瞬时水量大的特征。(3)各区域的顶板水灾隐患治理技术主要包括钻孔疏泄、注浆治理、开采参数控制等,底板水灾隐患治理技术主要包括区域注浆加固及封堵等;烧变岩水灾隐患主要采取帷幕注浆与钻孔探放有机结合的防治技术。

湿法磁选对粉煤灰中铁和重金属元素的分布影响研究

对煤粉锅炉粉煤灰(FA1灰)和循环流化床锅炉粉煤灰(FA2灰)采用湿法磁选的工艺达到降低其重金属含量的目的。利用扫描电子显微镜、激光粒度仪和X射线衍射仪表征两种粉煤灰在不同磁感应强度和不同磁选溶液浓度条件下磁选前后高磁性和弱磁性部分的形貌、粒度分布和物相分析,同时测定其铁元素和5种重金属元素(Hg、Pb、As、Cr、Cd)的含量变化,发现磁选后两种粉煤灰铁回收率随着磁感应强度增强而逐渐增加,高磁性组中重金属元素含量与弱磁性组有明显差异。结果表明:在磁感应强度为8000 Gs和磁选溶液浓度为20%(质量分数)时,FA1的铁回收率为71.2%,FA2的铁回收率为47.0%。此时FA1磁选后Pb含量差值为0.2 mg/kg、Cr含量差值为9.2 mg/kg、As含量差值为1.1 mg/kg;FA2磁选后Pb含量差值为18.1 mg/kg、Cr含量差值为25.0 mg/kg、As含量差值为9.1 mg/kg。

径向流氦氢分离床穿透特性实验与模拟分析

为系统深入研究径向流氦氢分离床的吸附穿透性能,指导结构设计,本研究借助COMSOL Multiphysics软件耦合材料吸氢动力学方程、流体流动动量方程和质量传递方程,建立了径向床穿透数学模型,并结合实验验证了模型的可靠性,利用模型对特性参数进行参数化扫描,分析其对穿透性能的影响。结果表明,穿透实验结果与模拟数据符合较好,模型可靠。通过分析温度、高径比及孔隙率等参数对床体穿透性能的影响,推荐氦氢分离床床体参数如下:床体吸附温度为室温~343 K,在该温度范围内升高温度对传质区长度及出口处浓度-时间曲线影响较小;随着高径比的增加,床体效率明显下降,其中高径比为2.00~8.33时,维持高效率的时间较长;随着孔隙率的增加,床体吸附效率明显下降,考虑床层的吸附效率、压阻效应及粉末的装填难度,粉末孔隙率推荐0.56~0.64。以上结果表明,本研究建立的模型可较好地预测床体的吸附分离性能,可用于床体结构设计以及工艺参数的优化。

我国不同类别煤层顶板水害致灾机理与防控路径

我国是世界上成煤和赋存条件最复杂的国家,煤层顶板水文地质条件的多样性和复杂性,采动覆岩裂隙场与渗流场耦合的相互性和时变性以及煤层顶板突水的独特性和危害性,造成顶板水害是我国尤其是西部煤矿区的主要矿井灾害之一。为了更好地认识顶板水害和推广现有技术和探索新技术防控此类矿井灾害,在全面分析近年来我国煤层顶板水害事故规律与顶板充水含水层的赋存条件、突水模式、动力特征、力学行为等基础上,系统划分了顶板水害的类型、特征、主要类别的致灾机理及梳理了现有顶板水害的防治技术,并展望了未来顶板水害防治领域的发展方向。研究发现:①顶板水害主体架构包括巨厚基岩含水层涌(淋)水、薄基岩弱胶结层水-砂耦合溃涌、离层空间蓄水储能突水、天窗补给型突水、围岩烧变增透致突等5种类别,集中分布于秦岭—淮河沿线以北地区,陕、蒙、宁是顶板水害主要聚集地。②采动诱发巨厚基岩含水层下覆岩原生裂隙互馈-贯通发育“Z”型离层空间,导致采场出现大面积涌(淋)水现象;基于复合关键层破断力学条件,阐明了薄基岩弱胶结层水-砂耦合溃涌致灾的动力源;构建了离层失稳突水临界判别准则,将离层突水划分为静载扰动、“动+静”载复合扰动、复合煤层开采重复扰动3种模式;红土隔水层缺失及红土薄弱区采动劣化损伤是产生天窗越流补给的主要根源;围岩烧变增透,孔隙度增大,接受临近水源补水后形成新的含水结构体,在采动诱发下烧变岩水涌入采场发生水害事故。③梳理了当前煤层顶板水害“探-放-治”三位一体的解危防控技术体系,提出了井上下共轭联动、钻-采(掘)高位协同地质勘探系统,以防治水“三区”划分为导向的地质保障工作,“煤-水-生态”多目标齐抓共管的绿色开采和防治水理念,以及数智化、透明化矿山水文地质灾害信息维护系统等未来发展方向。

稠密气固分选流化床介质颗粒团聚特性研究

为掌握介质颗粒的团聚特性,给形成均匀稳定的流化床层提供指导,分析了不同水分含量下0~300μm介质颗粒流化后的表观黏度,并研究了煤炭外水含量、介质粒度对颗粒团聚特性的影响。结果表明,水分含量越高、颗粒粒度越细,颗粒表观黏度越大;随着剪切速率的增加,颗粒表观黏度逐渐下降。随着水分含量升高,各粒级颗粒团聚过程相似,粒级0~74μm、74~150μm、150~300μm颗粒形成稳定聚团所需水分含量分别为0.75%、1.0%、1.25%,即粒度越细所需水分含量越低。水分含量越高,聚团尺寸越大;粒度越小,聚团的尺寸分布跨度越宽。随着水分含量升高,煤粉混合后的二元加重质颗粒聚团尺寸在水分含量1.75%时明显增大,聚团尺寸分布跨度窄,表明二元加重质颗粒聚团对水分变化敏感度较低。

多粒级干扰床对粗煤泥的分选效果研究

分析了粗煤泥干扰床分选机的分选原理及干扰床分选机内部流场特征和物料运行轨迹,当粗煤泥物料粒度范围较宽时,干扰床分选机分选效果变差;提出分粒级入选的分选方式,优化设计出一种多粒级入选干扰床分选机,并进行常规干扰床分选机与多粒级入选干扰床分选机的分选效果对比实验。实验数据表明,使用多粒级干扰床分选机分级入选较常规干扰床分选机混合入选的精煤泥产率提高4.83%,证明了多粒级干扰床分选机在处理宽粒级粗煤泥物料时可以取得较好的分选效果。

绿水洞煤矿选煤厂粗煤泥系统改造实践

绿水洞煤矿选煤厂由于缺少粗煤泥回收环节,导致1~0.25 mm部分粗煤泥直接回收作为中煤,造成粗精煤泥产品的损失,影响了选煤厂综合经济效益。结合现场实际及工艺分析,制定并实施了分级旋流器+FBS流化床分选机+叠层高频细筛+煤泥离心机的粗煤泥回收系统优化改造方案。改造实践表明,系统稳定运行,粗精煤泥灰分稳定控制在10%~10.5%范围内,粗精煤泥产量5.88万t/a,有效减少了精煤损失,为选煤厂提质增效发挥了积极作用。

吸附剂对多环芳烃吸附分离技术的研究

采用专用模板剂制备多环芳烃吸附剂,通过X射线衍射仪(XRD)、全自动比表面分析测试仪(BET)、程序升温化学吸附分析仪(NH_(3)-TPD)、吡啶吸附红外光谱仪(Py-IR)、扫描电镜和透射电镜测试仪(SEM/TEM)等表征方法对是否添加模板剂的吸附剂进行表征分析,并以模拟油品为原料,分别在固定床和模拟移动床吸附分离装置上,考察吸附剂的多环芳烃分离性能。结果表明,与未添加模板剂的吸附剂相比,添加模板剂的多环芳烃吸附剂平均孔径增加43.3%,微孔比表面积降低72.2%,微孔孔容降低87.5%,弱酸量提高31.2%,强酸量提高60%,多环芳烃/非芳烃相对分离度提高52.7%,多环芳烃解吸时间缩短41.4%,甲基萘饱和吸附容量提高14.6%。专用模板剂制备的多环芳烃吸附剂在模拟移动床装置上稳定运行30 d后,非芳烃产品的非芳烃质量分数>95%,多环芳烃产品的多环芳烃质量分数>95%。

分子筛吸附剂对不同类型柴油吸附分离性能的研究

采用离子交换法制备分子筛吸附剂,分析发现分子筛吸附剂的孔结构以晶内微孔为主,并含有晶间介孔,具有结晶度高、晶粒分布均匀、弱酸和强酸协同作用的特点。以不同类型柴油为吸附原料和轻型解吸剂(沸点低于柴油),利用模拟移动床分离装置,考察分子筛吸附剂对不同类型柴油的吸附分离性能。结果显示:在吸附温度为120℃、压力为1.2 MPa、吸附区回流比为0.5~1.5、精制区回流比为0.2~1.5、解吸区回流比为2.0~6.0、隔离区回流比-2~0的条件下,分子筛吸附剂在不同类型柴油吸附-脱附体系下运行稳定,芳烃产品中芳烃纯度>95%,非芳烃产品中非芳烃纯度>95%;不同类型柴油中硫氮含量、馏程轻重和芳烃含量对吸附分离效果没有影响,不同类型柴油中芳烃含量越高,解吸剂与柴油体积比越高,在模拟工业应用条件下,分子筛吸附剂稳定运行时间超过600 d,所制得的分子筛吸附剂具有芳烃选择性高、吸附容量大、运行稳定性高等特点。

石脑油正异构烷烃吸附分离技术

从吸附材料出发,对当前石脑油正异构烷烃吸附分离技术的研究进行梳理和总结,分别从正构烷烃分离材料、异构烷烃分离材料、单支链和双支链烷烃分离材料3方面对研究进展进行综述,进一步对正构烷烃分离的工业应用进行简要介绍。最后对该领域存在的问题进行总结和分析,并对技术的发展方向进行展望。

模拟移动床色谱分离技术研究进展

模拟移动床色谱(Simulated moving bed chromatography,SMBC)是一种新型分离手段,具有分离效果好、投资成本少以及适合连续性大规模生产等特点,近些年来备受关注,研究热度居高不下,在食品、化工和制药等行业均有广泛应用。SMBC由模拟移动床技术与色谱分离技术相结合产生,通过回顾色谱分离技术的起源,介绍模拟移动床色谱分离技术的原理及应用领域,列举模拟移动床色谱在高效分离淀粉糖、低聚糖、糖醇及有机酸等混合物的实际应用场景,为该技术的工业应用提供参考。