Studies in magnetochemical engineering. 1. A pilot-scale study of high-gradient magnetic desulphurization of solvent-refined coal (SRC)

A pilot-scale high-gradient magnetic separation (HGMS) system for the magnetic filtration of mineral residue from liquefied coal has been designed and constructed. The system is equipped with a specially designed on-line product-sampling device for obtaining time-cut samples of the magnetically cleaned product at elevated temperatures and pressures. Filter feed slurries of Illinois No. 6 and Kentucky No. 9/14 coals obtained from SRC pilot plants at Wilsonville, Alabama and Tacoma, Washington have been magnetically filtered under a wide range of separation conditions. The effects of major separation variables on the removal of inorganic sulphur and extracted solids from SRC filter-feed slurries have been quantitatively investigated. Under optimum separation conditions observed in this study, HGMS effectively removes up to 93 wt % of the inorganic sulphur. A quantitative correlation between the magnetic desulphurization performance and separator capacity applicable over a wide range of separation conditions has been found experimentally. A comparison of the present work and reported exploratory bench-scale studies is given, and a new SRC processing scheme incorporating HGMS capable of achieving over 90 wt % total sulphur removal from pulverized feed coal is also suggested.     

The Application of High Field and High Gradient Methods to the Magnetic Separation of Mineral Matter from Micronized Coal

Abstract

In exploratory laboratory measurements, high field high gradient magnetic separation (HGMS) has removed as much as 74% of the mineral matter and 99% of the pyritic sulfur from micronized coals with mineral contents up to 16.39 wt%. Magnetic cleaning methods are limited by the fact that not all mineral matter in coal is magnetic. HGMS methods are further restricted when mineral matter levels generally exceed about 2 to 3% because of excessive capture-matrix loading which leads to poor clean coal weight yields. The use of selective flocculation of coal mineral matter and processing at high flow velocities (made possible with the use of high field superconductive magnet technology) offer hope for overcoming these process limitations and for extending use of HGMS technology to preparation of low ash and low sulfur coal-slurry fuels. Measurements of mineral matter and sulfur removals achieved in high field HGMS processing of water slurries of dispersed micronized coals are presented. Field strengths up to 15 Tesla, flow velocities up to 3 cm/s, and slurry solids up to 38.4% were investigated. The use of models of the magnetic capture mechanism for scaling laboratory data to commercial applications is discussed.     

煤的高梯度磁场脱硫的基础研究

本文阐述了高梯度磁场分选(HGMS)的理论基础;着重分析了煤系矿物磁性质的研究结果和我国高硫煤进行高梯度磁场脱硫的工艺可行性,并在此基础上讨论实现煤的高梯度磁场脱硫的技术途径。     

过热蒸汽下煤系黄铁矿磁性强化研究

对西山煤电集团煤样进行热处理实验研究,在高温水蒸气气氛下、热解温度在400～700℃之间,利用自制热解装置热解预处理煤样,预处理后的煤样用自制PM—C30型圆筒磁滤器磁选脱硫研究,主要研究热解温度对煤粉磁选脱硫效果的影响。发现提高热解温度对磁选脱硫效果有利,在500℃时脱硫效果最好,此时的脱硫率为56．86％,与原煤脱硫率相比提高了40．49％;对于西山煤来说,热解一磁选脱硫技术能够有效脱除无机硫,但是对有机硫脱除效果不佳。     

Desulfurization of coal through pyrolysis in a fluidized-bed reactor under nitrogen and 0.6% O2-N2 atmosphere

The raw Yima (YM) and Datong (DT) coal, their demineralized (YM-ash, DT-ash) and de-pyrite (YM-p, DT-p) coals were pyrolyzed in a fluidized-bed reactor to examine the sulfur removal efficiency. The effect of process parameters such as temperature, residence time and atmosphere were investigated. The results show that there is an optimal temperature and residence time for the maximum desulfurization, varying with type of coal and the thermal stability of organic sulfur. The alkaline-earth mineral in the raw coal plays an important role for the fixation of sulfur and makes desulfurization decrease. The interaction of pyrite with the organic matrix of coal is the dominant reason that leads to organic sulfur accumulation in char. YM has higher desulfurization of organic sulfur than DT due to more aliphatic sulfur in the raw coal. YM and DT were pyrolyzed in 0.6%O₂-N₂ mixed atmosphere, aiming at examining the effect of reactive gas on the sulfur removal during pyrolysis. The results show that sulfur removal is improved without great decrease in char yield. This indicates that small amount of O₂ in inert atmosphere can improve desulfurization efficiency. In addition, TG-MS runs in 0.6%O₂-Ar and Ar were carried out to check the sulfur-containing compounds in pyrolysis gas and further understand the desulfurization process.     

煤系矿物表面磁性强化技术的研究

煤系矿物的表面磁性强化是利用通常磁选设备实现高硫煤脱硫脱灰的新型关键技术。本文着重对热处理、选择性磁罩盖、氧化或还原、微波辐照预处理以及表面磁性的溶液电化学调整等方法和煤脱硫作用原理进行了综述和探讨。     

煤中黄铁矿的电化学脱硫及动力学研究

为了降低煤的脱硫费用和提高脱硫效率，以硫酸为介质，以硫酸锰为脱硫催化剂，在以石墨为电极的无隔膜电解池中研究了煤的电化学催化脱硫。研究表明，在特定的电解电位下，煤中无机硫脱硫率随着锰离子的浓度增加，煤浆浓度的降低和电解温度的提高而提高。进而对这些数据进行了动力学分析。结果表明：煤中黄铁矿脱硫速率与煤中活性黄铁矿（易接近）和惰性黄铁矿（难接近）及脱硫反应有关，脱硫模型符合Langmuir-Hinshelwood近似，脱硫表观活化能为10.44kJ/mol。     

气流床烟气干法脱硫技术的初步试验研究

介绍了新型燃煤烟气干法脱硫并回收硫技术的工艺流程概念。其特点是利用可再生煤基脱硫剂细粉进行干法连续脱硫, 脱硫过程在下喷式气流床中完成; 采用间接换热式脱硫剂热再生, 生成含高浓度二氧化硫的再生气体; 加压、冷却再生尾气, 其中的二氧化硫液化并与其它气体组分相分离, 进而生产液体二氧化硫副产品; 并介绍了烟气脱硫、脱硫炭再生和再生尾气液化的单元试验研究结果。     

Retrograde reactions in SRC-I liquefaction

Operating the vapour-liquid separators in the solvent refined coal (SRC-I) process at or near the reactor temperature is desirable to retain the heat in the liquid product stream which is necessary for subsequent distillation. However, adverse changes in the product composition resulting from high temperature operation (i.e., ‘coking’) would obviate this advantage. A study of these potential retrograde reactions using a 4.5 kg h^?1 bench-scale coal liquefaction unit is reported. At high pressure, separator temperatures up to 722 K and residence times in the pressure let-down system of 15 to 30 min, retrograde reactions occur as conversion of a few per cent of the product SRC to insoluble organic matter. If sufficient agitation is present in the separators these retrograde reactions would have little effect on product yields or unit operability. Coking, manifested as the accumulation of significant deposits of anisotropic carbon in the separator vessels, occurs only with the extended time-at-temperature that the solids can experience in a poorly agitated vessel.     

电化学法在煤炭预脱硫中的应用

脱硫是煤炭工业和电力工业中煤炭的洁净燃烧和加工技术的研究重点,目前有燃烧过程中脱硫和烟气脱硫,均为燃烧后的脱硫技术。近年来,多种新型的燃烧前脱硫技术涌现,电化学脱硫法为其中之一,通过电氧化作用将煤炭中的低价态无机硫和有机硫氧化为硫酸盐硫,达到脱硫的目的。本文综述了该技术的几种典型形式、脱硫原理、研究进展及其在实际煤炭处理中的应用情况,展望了电化学技术在前置煤脱硫中的发展方向和应用前景。     

煤的电化学脱硫及其进展

综述了煤炭电化学脱硫的原理 ,借助煤在电解槽阳极发生的电化学氧化反应将煤中的无机硫或有机硫氧化成可溶于水的硫化物 ,介绍了电解脱硫设备及工艺流程、电化学脱硫技术发展方向及趋势 ,认为该方法的显著特点是常温常压下操作 ,工艺简便 ,能量回收率高 ,并可联产大量高纯氢气 ;同时也指出了煤炭电化学脱硫技术中存在的问题     

以RTS为催化剂的湿法氧化脱硫技术

介绍了以RTS为催化剂的湿法氧化脱硫技术和实际运行效果。RTS催化剂脱硫效率高,不仅能脱除无机硫,还能脱除部分有机硫,析出的硫磺颗粒大且均匀。实践证明,该脱硫工艺运行与脱硫效果稳定,净化气中H2S含量为10-20mg／m^3。可满足使用高硫煤的脱硫需要。     

高硫煤合理分选与减少重庆市二氧化硫排放的途径分析

通过对南桐矿务局多年来在高硫煤洗选加工,烟道气脱硫,燃烧固硫及高温固添加剂上所做工作的分析总结,提出“配煤＋筛分降硫＋洗选脱硫＋固硫添加剂掺配＋副产品选硫”等一条龙洁净煤技术的综合应用,是高硫动力煤合理分选,洁净利用的发展方向,与单纯烟道气脱硫,重庆市     

Supercritical desulfurization kinetics of illinois no. 5 coals

This paper describes a desulfurization process to remove both organic and inorganic sulfur from coal employing alcohols under supercritical conditions. The overall objective of this study was to gain a better understanding of the kinetics of the supercritical alcohol/coal desulfurization process. A microreactor system was developed to examine in detail the reaction kinetics of coal desulfurization under supercritical conditions. The microreactors provide a uniform temperature within the reactor and allow precise measurement of temperature. Desulfurization tests were conducted to obtain solid residues for sulfur analysis (% in product), as well as optical microscopic examination. The results of the analysis indicate that the desulfurization process is highly temperature dependent. Generally, with increased reaction temperature, desulfurization is increased. For all isothermal reactions there is at least one stage at which sulfur is reincorporated into the product. Pretreatment of coal with 5% KOH is desirable to prevent coke formation, but under the conditions studied, had little effect on ultimate desulfurization levels. Additions of KOH increased the rate at which ultimate desulfurization levels were reached.     

高硫煤粉永磁干法强磁选试验研究

以平顶山庚组高硫煤粉为煤样,利用实验室自制的永磁强磁选机进行分选试验,发现:随着颗粒粒径的增大,其灰分、硫分也随之增加;该磁选机的最佳分选粒度范围为0.25～0.5mm;磁选脱除的主要是煤中黄铁矿硫,而硫酸盐硫和其他有机硫则变化不大。     

煤炭高梯度磁选-浮选脱硫降灰试验

通过分析煤样性质,说明原煤中无机硫主要以硫化铁硫为主,有机硫较高,仅依靠物理方法很难达到理想脱除效果。通过煤粉高梯度磁选试验研究了磁介质、磁通密度、脉冲对煤炭磁选效果的影响。结果表明:聚磁介质选用不加铜套细网介质,当磁通密度为1.295 T,脉冲为25次/min时,煤粉湿法高梯度磁选脱硫效果最好,此时硫分为1.59%,精煤产率为85.44%,脱硫率为31.87%,脱灰率为38.17%,黄铁矿硫脱除率为45.02%。通过正交试验确定了最佳高梯度磁选条件为:煤粉粒度0.075 mm,磁通密度1.295 T,脉冲25次/min,可得到硫分1.35%,灰分10.37%的磁选精煤产品。最后对磁选精煤进行再浮选试验,得到最佳浮选条件为:石灰500 g/t,捕收剂1360 g/t,起泡剂90 g/t,可获得产率76.29%,硫分1.28%,灰分8.14%的精煤,产品脱硫率为57.73%,脱灰率为58.52%,黄铁矿硫脱除率为84.56%。采用磁选-浮选综合流程,煤粉基本达到理想的脱硫降灰效果,可作为煤种脱硫降灰技术方案的参考。     

高硫煤燃前脱硫技术

根据煤炭中有机硫和无机硫的存在状态,简述了当前高硫煤燃前脱硫技术的3种主要方法：物理法、化学法及生物法,指出当前煤炭脱硫必须以发展燃前的物理脱硫放在首位,以燃中固硫和燃后烟道气脱硫为补充的脱硫技术,实施联合开发,综合治理,坚持科学发展观,走集约型、质量型经济增长的道路,促进我国煤炭工业可持续发展。     

Microwave irradiation pretreatment and peroxyacetic acid desulfurization of coal and application of GRNN simultaneous predictor

Artificial neural network was used to predict the effects of operational parameters on coal desulfurization using peroxyacetic acid from microwave pretreated coal. Coal particle size (150–1125 μm), leaching temperature (25–85 °C), leaching time (0–120 min), microwave irradiation power (0–1000 W) and time (0–110 s) were used as inputs to the network. The outputs of the model were organic and inorganic sulfur reductions for 40 of the data sets. The GRNN artificial neural network with spread of 0.3 was used to estimate both organic and inorganic sulfur reduction from a combined database, which was established from microwave pretreatment and leaching experiments. Thirty-two data sets were used for training and eight data sets for testing. Simulated values obtained from the neural network, correspond closely to the experimental results. Satisfactory correlations of R² = 0.99 and 0.97 were achieved during the testing stages of the prediction of inorganic and organic sulfur reductions respectively.     

微波辐照下煤的电化学脱硫研究

以北宿煤为原料,利用微波选择性加热的特点,考察了微波辐照时间、煤样粒径、NaOH等因素对高硫煤磁性强化磁选脱硫的影响,同时考察了微波-NaOH饱和溶液联合处理对北宿煤磁选脱硫的影响。研究表明,不同粒径的煤样的最大脱硫率存在一个最佳微波辐照时间,而微波-NaOH联合处理法脱硫效果更为显著。对煤样进行微波预处理后,可以根据需要控制NaOH饱和溶液用量达到较为理想的脱硫效果。     

高硫煤的微波脱硫研究

考查了高硫煤直接微波处理、浸渍不同浓度NaOH溶液后微波处理及其与磁选相结合的手段对脱硫效率的影响,结果表明:高硫煤样直接经微波辐照处理具有一定的脱硫效果,但脱硫率较低。原煤经不同NaOH溶液浸渍后,再经微波处理,其脱硫效果明显提高。在采用2 mol/L NaOH溶液浸渍后,经700W微波功率处理60s,其脱硫率达到最大,为45.2%。磁选对脱硫效率的影响受微波功率的影响较大。在本实验条件下,采用900W微波功率处理,经磁选后脱硫率明显提高。