VOLATILE EVOLUTION OF PULVERIZED COAL IN AN ENTRAINED FLOW REACTOR

ABSTRACT

A finite difference method and the code Furnace of J.H. Kent were used do calculate the particle temperature and residence time in an entrained flow reactor. Then, three kinds of Chinese coals were pyrolyzed in the reactor. The auther analysed the chemical reaction mechanism of coal pyrolysis. Considered the coal pyrolysis as a parallel reactions of functional groups. Related the individual volatile species formation to elementary free radical steps. Developed a new volatile evolution model.Thepredictions agreed quantitatively with the experimental data of rapid pyrolysis in the overall weight loss and individual volatile species.     

化学链热解煤焦油工艺的模拟及优化

为了得到化学链热解煤焦油制备炭黑系统的优化运行参数,以Aspen Plus为平台建立了模拟流程。以炭黑产率、煤焦油转化率、产气率和能量转化率为评判指标,得到了系统优化的操作条件,并分析了操作参数（燃料反应器温度、反应时间和载氧体/煤焦油摩尔比、操作压力）对热解产物的影响。结果表明,在温度900℃,反应时间3 s,载氧体/煤焦油摩尔比为5.2,操作压力为0.75 MPa的条件下,炭黑产率最大,此时煤焦油转化率为99.5%,产气率为3.39,系统的能量转化率为85.7%。     

REACTION RATE OF MICROWAVE PYROLYSIS OF COAL IN CHAR BED

A subbituminous coal mixed with mild gasification char was pyrolyzed in a microwave reactor of 2.4 5 GHz and power input varying from 4 50 to 650 W. Gas evolution was observed immediately after microwave energy was applied to the mixture. Data obtained from the tests are analyzed to estimate coal pyrolysis kinetic parameters. A reaction order of 1.75 was found to best fit the experimental data. Both an activation energy and reaction rate constant are found to be essentially dependent on the amount of coal content in the mixture. There is a clear trend of an activation energy increase and reaction rate constant decrease with the change of coal concentration in mixtures from 30 to 60 %, Due to the presence char, an activation energy of coal pyrolysis in the microwave reactor was reduced from one-third to one-fourth of that known for the conventional method. This reduction in activation energy is one of the major reasons for the enhancement of coal pyrolysis by microwave energy.     

GENERATION, CONTROL, ANO RECOVERY OF ORGANIC PYROLYSIS PRODUCTS IN UNDERGROUND COAL GASIFICATION

The organic chemical substances present in UCG- affected subsurface waters are formed by the thermal degradation of coal. After a UCG reactor is shut down, the sensible heat contained in the rubble pile is sufficient to continue coa1 pyrolysis. If the pyrolysis products are not removed. they become a potential source of sub surface water contamination. Heat transfer into the coal seam and migration c if chemical substances after reactor shutdown can be sub stantially reduced by a controlled influx of water through the cavity side wal1s and removal of produced fluids from the reactor.     

GENERATION,CONTROL, ANO RECOVERY OF ORGANIC PYROLYSIS PRODUCTS IN UNDERGROUND COAL GASIFICATION

ABSTRACT

The organic chemical substances present in UCG- affected subsurface waters are formed by the thermal degradation of coal. After a UCG reactor is shut down, the sensible heat contained in the rubble pile is sufficient to continue coa1 pyrolysis. If the pyrolysis products are not removed. they become a potential source of sub surface water contamination. Heat transfer into the coal seam and migration c if chemical substances after reactor shutdown can be sub stantially reduced by a controlled influx of water through the cavity side wal1s and removal of produced fluids from the reactor.     

低阶煤固定流化床热解及半焦气化实验研究

采用固定流化床研究了三种低阶煤的常压热解及其热解半焦的气化特性,探究了样品粒度、反应温度、反应时间及流化气中O2含量对上述过程的影响,确定了循环流化床热解-气化耦合工艺适宜的反应条件。结果表明,在实验选择范围内,样品的粒度基本不会影响热解过程,在水蒸气气氛下,温度越高,热解气体产率越高,半焦产率越低;600 ℃和20 min时能获得最高的焦油产率。循环流化床热解-气化耦合工艺碳的有效利用率率高于原煤固定流化床气化工艺,同时副产煤焦油;温度越高,有效气产率和有效碳转化率越高;实验范围内,O2含量对合成气产率的影响较小,但可以调节H2和CO的相对含量;900 ℃、半焦气化15 min即可获得较理想的合成气产率及有效碳转化率。     

不同升温速率下的非等温热解特性及动力学

探究诸如煤等化石燃料在热解过程中的动力学行为是开发和优化相关工艺的基础。本文借助热重仪探究煤样在加热速率分别为10,40,70,100,200,500℃/min下的热解特性和动力学。根据TG/DTG曲线,热解过程可分为四个阶段,第一阶段主要是挥发物的脱除反应,第二阶段是则主要进行一次挥发物的缩聚反应。研究发现热解过程中在较高升温速率下挥发物更容易从煤样品中释放出来,且快速升温时需要更高的温度来完成热解反应。动力学结果显示无模型（KAS和 FWO）和Coats-Redfern两种方法都能确切描述热解过程,而且两种动力学模型计算所得活化能的变化一致。升温速率不能改变整个热解过程中的反应顺序,但较高的升温速率可以使热解初始反应阶段的活化能减小。     

煤生烃过程中成熟度引起的碳同位素分馏效应

通过半封闭体系下的生排烃热模拟实验研究了3种煤在不同热解温度下的碳同位素分馏效应。研究结果表明,煤的有机质类型不同,成熟度造成的热解烃的碳同位素分馏效应也有差别,腐植煤的热解烃基于成熟度的碳同位素分馏效应大,而煤本身的碳同位素值随成熟度的变化不大。在较高成熟度时,二次裂解的概率大大增加,导致热解烃尤其是残留烃的正构烷烃单体碳同位素组成明显变重。同一烃源岩在不同温度下的热解烃正构烷烃单体的碳同位素组成曲线具有很大的相似性,说明在油源对比中正构烷烃单体碳同位素值曲线的形状和其数值一样都是重要的对比依据。      

煤样ZnCl_2分离液之比重与热解参数T_(max)的关系

本研究探讨利用ZnCl2 分离液分离显微组分时不同的ZnCl2 分离液之比重对热解参数Tmax的影响 ,实验上利用单一煤样 (台湾裕峰煤 )配制几个不同比重的ZnCl2 分离液 ,将煤样浸泡其中再各分成两部分 ,一部分直接晾干 ,另一部分清洗煤样中的ZnCl2 分离液后再行晾干。最后将所有样品进行热解分析。结果显示 ,Tmax值随着ZnCl2 分离液比重的增加而有提前到达的趋势 ,而在洗除含有不同比重ZnCl2 分离液的煤样 ,可恢复此样品应的的Tmax值。这说明ZnCl2 分离液比重的增加有加强催化的效果 ,同时亦显示热解参数Tmax值的稳定性。     

RAPID PYROLYSIS OF EASTERN CANADIAN COALS BY FREE FALL REACTORS

The effect of temperature was investigated on the rapid pyrolysis of Prince, Lingan and No. 26 coals in the temperature range of 525^° to 750^°C using a 600 cm high stainless-steel free fall reactor at atmospheric pressure.

The yields of char, condensibles and gaseous products were determined at 25^°C intervals. Gaseous products were analysed for H₂, CO, CO₂, CH₄ and C₂+.

Volatile product (condensible and gas) yields exceeded the volatile product in the A.S.T.M. methods at and above 700^°C.

Some experiments using Prince coal were repeated at reduced pressure (50 mm mercury) in both the 600 cm height stainless-steel and a 140 cm height quartz reactor in order to find out the effect of pressure and retention time.

The experimental results indicated that the condensable yield was higher at the lower pressure and at the shorter retention time. The effect of retention time was far more pronounced.     

煤样ZnCl2分离液之比重与热解参数Tmax的关系

本研究探讨利用ZnCl₂分离液分离显微组分时不同的ZnCl₂分离液之比重对热解参数T_max的影响,实验上利用单一煤样(台湾裕峰煤)配制几个不同比重的ZnCl₂分离液,将煤样浸泡其中再各分成两部分,一部分直接晾干,另一部分清洗煤样中的ZnCl₂分离液后再行晾干。最后将所有样品进行热解分析。结果显示,T_max值随着ZnCl₂分离液比重的增加而有提前到达的趋势,而在洗除含有不同比重ZnCl₂分离液的煤样,可恢复此样品应的的T_max值。这说明ZnCl₂分离液比重的增加有加强催化的效果,同时亦显示热解参数T_max值的稳定性。      

N2和CO2气氛下辽河稠油热解过程及产物性质

利用热重分析仪（TGA）和固定床反应器对辽河Q块稠油在N₂和CO₂气氛下的热解过程及产物性质进行了研究。TGA实验结果表明,2种气氛下的稠油热解过程均可划分为轻组分与水分挥发、组分较弱化学键断裂和重组分裂解产油成焦3个阶段,热解曲线总体变化趋势类似。固定床反应器热解实验结果表明,随温度升高,2种气氛下的液体产物产率均升高,热解气和残余物产率均降低,CO₂气氛下650 ℃液体产物最大产率为61.53%。不同温度下热解所得液体产物和稠油的红外谱图显示,随热解温度升高,甲基含量增多、亚甲基含量减少。对液体产物的氧化过程进行TGA分析发现,随热解温度升高,其失重曲线向高温区明显偏移且失重程度减弱,CO₂热解所得液体产物的氧化失重比N₂快。     

固定床反应器中生物油水溶性组分热解反应动力学

在空气气氛下采用热重分析法研究了固定床反应器中生物油水溶性组分的热解特性,利用Achar微分法和Coats-Redfern积分法相结合的方式进行动力学分析,计算了挥发和热分解的活化能、反应级数和动力学参数,确定了机理函数,并建立了热解动力学模型。结果表明,生物油水溶性组分的热解可分为3个阶段,即轻组分挥发段、重组分热解段和焦炭燃烧段,重组分热解段活化能较轻组分挥发段的活化能低很多。轻组分挥发段反应级数近似为一级,可采用一级反应模型来模拟,而重组分热解段反应级数近似为二级,可采用二级模型来表示。     

RAPID PYROLYSIS OF EASTERN CANADIAN COALS BY FREE FALL REACTORS

Abstract

The effect of temperature was investigated on the rapid pyrolysis of Prince, Lingan and No. 26 coals in the temperature range of 525^° to 750^°C using a 600 cm high stainless-steel free fall reactor at atmospheric pressure.

The yields of char, condensibles and gaseous products were determined at 25^°C intervals. Gaseous products were analysed for H₂, CO, CO₂, CH₄ and C₂+.

Volatile product (condensible and gas) yields exceeded the volatile product in the A.S.T.M. methods at and above 700^°C.

Some experiments using Prince coal were repeated at reduced pressure (50 mm mercury) in both the 600 cm height stainless-steel and a 140 cm height quartz reactor in order to find out the effect of pressure and retention time.

The experimental results indicated that the condensable yield was higher at the lower pressure and at the shorter retention time. The effect of retention time was far more pronounced.     

含油污泥热解工艺及目标产物定位

以3种典型含油污泥(落地油泥、罐底油泥及煤焦油泥)为例,研究其热解产物的质量分布、性质和能量分布;并在此基础上,通过综合分析该热解系统能量平衡、不同工艺对应的环保效益和经济指标来确定油泥热解工艺方案和目标产物。研究表明, 3种油泥热解产生气体量均很少,利用气体产物燃烧不足以满足其热解供热的需求。对热解炭总热量大于等于1.8倍的热解系统需热量的煤焦油泥,工艺上应考虑将热解炭气化与热解产生的可燃气一起燃烧满足热解供热需求,目标产物为回收热解油。而对于无机组分含量高的落地油泥,推荐采用柴油供能并以回收热解油为目标产物。对于极黏稠、灰含量低的罐底油泥,其热解炭热值高且灰含量也低,具有回收价值,可作为目标产物;而其热解油应考虑采取降黏措施。     

裂解汽油在Co-Mo/Al_2O_3催化剂上的加氢—脱硫工艺条件

叙述了350cm~3绝热反应器的结构参数、绝热保温方式、以及裂解汽油二段加氢和脱硫的主要化学反应。并以工业装置的工艺操作条件为基础,在350cm~3绝热反应器中,试验了裂解汽油在8602Co-Mo/Al_2O_3催化剂上加氢和脱硫时反应器的入口温度、氢油比、液时空速和反应压力等工艺操作条件对加氢和脱硫反应的影响。给出了8602催化剂于绝热型反应器上的最佳工艺操作条件。     

低阶煤流化床热解气化新工艺

针对低阶煤流化床热解气化所遇到的问题,对热解炉供热模式、原料煤粒径与颗粒分级、热解气初级冷却与除尘、排灰方式等问题进行探讨,优化工艺过程。新工艺中选择高温半焦为热解炉提供热量,将原料煤磨制成亚毫米级粉粒,磨煤产生的少量粒径小于0.1 mm的细颗粒被分离出来,送往配套的气流床气化炉,与流化床气化炉气体带出的细粉一起进行熔渣气化,提高碳转化率。大量粒径为0.1~1.0 mm的颗粒进热解炉,热解炉出来的气体经适当馏分煤焦油冷却、捕集颗粒物,使温度降至350 ℃左右,采用间接换热模式进一步降温,由此将有机废水产量降至近零水平,实现清洁高效热解气化。以低阶煤4 600 t/d规模的流化床热解气化新工艺为例,干基煤粗粉进热解炉,干燥单元取水约480 kt/a,热解单元不产生有机废水,可产有效气体（氢气和一氧化碳）约1.09×10⁹ m³/a,产煤焦油约81 kt/a,系统碳转化率大于95%,煤焦油、煤气、半焦的产率分别为8.97%,110 m³/t,67.5%,半焦气化产物气中有效气体积分数大于80%。     

STUDIES ON SUCCESSIVE EXTRACTION OF COAL IN COAL DERIVED SOLVENTS UNDER AMBIENT CONDITIONS TO RECOVER VOLATILE MATTER (VOLATILIZABLE COMPONENTS) FROM COAL AND TO GET PARTIALLY DEVOLATILIZED RESIDUAL COAL AND SOLVENT REFINED COAL AS CLEAN AND DETOXIFIED FUELS

Effect of anthrecene oil, quinoline and liquid paraffin extraction on the swelling of Assam coal has been studied to find out the degree of cross-linking in the pretreated coals, and to assess the molecular effect of the these solvents in the solid mass of coal, on the flexibility of coal macromolecular aggregation and molecular dynamism. Effect of successive extractions using anthracene oil-quinoline-liquid paraffin sequence, on the extraction of volatilizable components i.e. volatile matter (VM) contents and removal of toxic mineral matter contents of Assam coal has been studied. A relation of C % and VM % in coal with extraction yields through this successive extraction of different coals has been suggested. About 50 - 76% of the total VM present in the original coal can be extracted by the successive solvent extractive disintegration of coal, which was more than that through pyrolysis of coal at 600°C. Recovery of VM renders the combustion of residual coal free of pollution. The solvent refined coal is also obtained as a clean fuel. Thus, the process affords the segregation of toxic mineral matter microconstituents. Solvent extraction should be introduced as the essential coal preparation step to remove the premium organic products from coal before firing it in boilers.     

A Review of:“Geochemistry of Sulfur in Fossil Fuels” Edited by Wilson L. Orr and Curt M. White American Chemical Society Symposium Series 429 American Chemical Society,Washington, D.C. 1990, xi + 708 pp.

ABSTRACT

A two step process of organorefining (successive solvolytic extractions) using anthracene oi1-ethylenediamine-liquid paraffin followed by steam carbonization of coal afforded clean fuels from coal with higher heating values. Effect of heating rate and final temperature of pyrolysis on the pyrolysis of residual coal obtained after organorefining was studied. More than 60% coal was recovered as clean fuels by this process. Pretreatments such as reduction, depolymerization and reductive-depolymerization enhance the devoiati1ization yield through steam pyrolysis. The use of steam in pyrolysis inhibited condensation reactions and promoted the cracking of phenolic and condensed polycyclic aromatic ring structures. Dynamics of the two stage process has been studied. The observation that coal consists of 5 different types of molecules has been supported by the evidence. Behaviour of different types of coal molecules in the stepwise coal conversion is explained. Successive extraction by selected solvents followed by pyrolysis of residual coal obtained can be a useful technique for the studies of organic chemical structure of coal.     

煤系有机质生烃潜力评价标准探讨

根据西北地区侏罗纪煤系地层２３００余个岩样的有机地化分析数据,详细研究了３类煤戏夺的热解生烃潜量与有机碳、氯仿沥青“Ａ”、总烃含量的关系。对煤系烃源岩的评价,不能简单套用一般湖相泥岩的评价标准。有机碳含量为２－５％的煤系泥岩是煤系中最好的油源岩;煤的生烃能力主要取于煤中富氢显微组分的含量,其有机碳含量与热解生烃兴师动众量没有相关关系;碳质泥岩的热解生烃潜量与其有机碳含量的相关性很差,用热解生烃潜量