Influence of temperature and Ca(OH)2 on releasing tar and coal gas during lignite coal pyrolysis and char gasification

The yield of tar and syngas has been investigated by catalytic pyrolysis of Pingzhuang lignite(PZL)over Ca(OH)2 catalyst in temperature range of 600℃-1000℃in a tube furnace.The results show that the yield of volatile pyrolysis increases and char decreases with rising temperature for both raw and catalyzed Pingzhuang lignite.The hydrogen fraction(H2)increased from 20%to 40%for the PZL sample;but,for the PZL-Ca(OH)2 sample,H2 fraction fluctuated randomly between 35%to 42%,with the maximum H2 fraction found at 1000℃.The Gaschromatography mass-spectroscopic(GC-MS)analysis revealed that the maximum tar yield at 800℃and 700℃was obtained for PZL and PZL-Ca(OH)2,respectively.The surface morphology of PZL and PZL-Ca(OH)2 chars underwent different transformation in the presence of catalyst as illustrated by SEM/EDX,FTIR,and BET analysis.Furthermore,char sample was investigated for the carbon conversion and reactivity index using TGA analysis under N2 and CO atmosphere.

Effect of Temperature on the Molecular Weight Distribution in the Different Ranks of Coal during the On-Line Investigation of Coal Pyrolysis Gas Using Direct Photoionization Mass Spectroscopy

Coal pyrolysis gas from different ranks of coal was monitored on real time basis using photoionization mass spectroscopy. The molecular weight distribution of different products as a function of temperature from various coal ranks studied was observed. It was noted that the release of different classes of compounds like phenols, alkenes, alkylated aromatics and aromatic skeletons was temperature dependent. For all the coal ranks at lower temperatures phenols were the main component, with alkenes and alkylated aromatics at slight higher temperatures and aromatic skeletons were released at the highest temperatures studied.

Gas generation from coal: taking Jurassic coal in the Minhe Basin as an example

The gas generation features of coals at different maturities were studied by the anhydrous pyrolysis of Jurassic coal from the Minhe Basin in sealed gold tubes at 50 MPa.The gas component yields(C1,C2,C3,i-C4,n-C4,i-C5,n-C5,and CO2);theδ13C of C1,C2,C3,and CO2;and the mass of the liquid hydrocarbons(C6+)were measured.On the basis of these data,the stage changes ofδ13C1,δ13C2,δ13C3,andδ13CO2 were calculated.The diagrams ofδ13C1–δ13C2 vs ln(C1/C2)andδ13C2–δ13C1 vsδ13C3–δ13C2 were used to evaluate the gas generation features of the coal maturity stages.At the high maturity evolution stage(T>527.6°C at 2°C/h),the stage change ofδ13C1 and the CH4 yield are much higher than that of CO2,suggesting that high maturity coal could still generate methane.When T<455°C,CO2 is generated by breaking bonds between carbons and heteroatoms.The reaction between different sources of coke and water may be the reason for the complicated stage change inδ13CCO2 when the temperature was higher than 455°C.With increasing pyrolysis temperature,δ13C1–δ13C2 vs ln(C1/C2)has four evolution stages corresponding to the early stage of breaking bonds between carbon and hetero atoms,the later stage of breaking bonds between carbon and hetero atoms,the cracking of C6+and coal demethylation,and the cracking of C2–5.Theδ13C2–δ13C1 vsδ13C3–δ13C2 has three evolution stages corresponding to the breaking bonds between carbon and hetero atoms,demethylation and cracking of C6+,and cracking of C2–5.

Research on coal staged conversion poly-generation system based on fluidized bed

A new coal staged conversion poly-generation system combined coal combustion and pyrolysis has been developed for clean and high efficient utilization of coal.Coal is the first pyrolysed in a fluidized pyrolyzer.The pyrolysis gas is then purified and used for chemical product or liquid fuel production.Tar is collected during purification and can be processed to extract high value product and to make liquid fuels by hydro-refining.Semi-coke from the pyrolysis reactor is burned in a circulating fluidized bed(CFB)combustor for heat or power generation.The system can realize coal multiproduct generation and has a great potential to increase coal utilization value.A 1 MW poly-generation system pilot plant and a 12 MW CFB gas,tar,heat and power poly-generation system was erected.The experimental study focused on the two fluidized bed operation and characterization of gas,tar and char yields and compositions.The results showed that the system could operate stable,and produce about 0.12 m^(3)/kg gas with 22 MJ/m^(3)heating value and about 10 wt%tar when using Huainan bituminous coal under pyrolysis temperature between 500 and 600℃.The produced gases were mainly H_(2),CH_(4),CO,CO_(2),C_(2)H_(4),C_(2)H_(6),C_(3)H_(6)and C_(3)H_(8).The CFB combustor can burn semi-coke steadily.The application prospect of the new system was discussed.

Thermal simulation of the formation and evolution of coalbed gas

Thermal simulation experiment of gas generation from the peat and the coals were performed using the high temperature and pressure apparatus, at temperature ranging from 336.8-600℃, a pressure of 50MPa and two heating rates of 20℃/h and 2℃/h, and the evolution and formation of coalbed gas components were studied. Results show that for the coals, the gaseous products are mainly composed of hydrocarbon gases. However, for the peat the content of hydrocarbon gases in gaseous products is lower than that of non-hydrocarbon components. In the generated hydrocarbon gases methane is predominant and heavy hydrocarbon gases (C2-5) are present in small amount. Meanwhile, carbon dioxide (CO2) predominates the generated non-hydrocarbon gases, and hydrogen (H2) and sul-furated hydrogen (H2S) are existent in trace amount. It is also observed that temperature is the main factor controlling the evolution of coalbed gas generation. With increasing vitrinite reflectance, methane rapidly increases, CO2 sightly increases, and C2-5 hydrocarbons first increase and then decrease. The peat and Shanxi formation coal have a higher generative potential of coalbed gases than coals and Taiyuan formation coal, respectively, reflecting the effect of the property of organic matter on the characteristics of coalbed gas component generation. In this study, it is found that low heating rate is favorable for the generation of methane, H2 and CO2, and the decomposition of C2-5 hydrocarbons. This shows that heating time plays an important controlling role in the generation and evolution of coalbed gases. The results obtained from the simulation experiment in the study of coalbed gases in natural system are also discussed.

Mechanisms of carbon isotopic fractionation in the process of natural gas generation: Geochemical evidence from thermal simulation experiment

Low maturity coal samples were taken from the Ordos Basin to conduct gold tube thermal simulation experiment in a closed system,and the characteristics of the products were analyzed to find out the fractionation mechanism of carbon isotopes and the causes of abnormal carbon isotopic compositions of natural gas.At the heating rates of 2℃/h(slow)and 20℃/h(rapid),the low maturity coal samples of the Ordos Basin had the maximum yields of alkane gas of 302.74 mL/g and 230.16 mL/g,theδ13C1 ranges of-34.8‰to-23.6‰and-35.5‰to-24.0‰;δ13C2 ranges of-28.0‰to-9.0‰and-28.9‰to-8.3‰;andδ13C3 ranges of-25.8‰to-14.7‰and-26.4‰to-13.2‰,respectively.Alkane gas in the thermal simulation products of rapid temperature rise process showed obvious partial reversal of carbon isotope series at 550℃,and at other temperatures showed positive carbon isotope series.In the two heating processes,theδ13C1 turned lighter first and then heavier,and the non-monotonic variation of theδ13C1 values is because the early CH4 is from different parent materials resulted from heterogeneity of organic matter or the carbon isotope fractionation formed by activation energy difference of early enriched 12CH4 and late enriched 13CH4.The reversal of carbon isotope values of heavy hydrocarbon gas can occur not only in high to over mature shale gas(oil-type gas),but also in coal-derived gas.Through thermal simulation experiment of toluene,it is confirmed that the carbon isotope value of heavy hydrocarbon gas can be reversed and inversed at high to over mature stage.The isotope fractionation effect caused by demethylation and methyl linkage of aromatic hydrocarbons may be an important reason for carbon isotope inversion and reversal of alkane gas at the high to over mature stage.

裂解气相色谱-质谱法分离鉴定聚氨酯防水涂料中的煤焦油

建立了采用闪蒸裂解气相色谱-质谱测定固化后的聚氨酯防水涂料中的煤焦油的新方法。该方法方便快捷,无需对样品进行前处理,而且测定结果不受聚氨酯组分的干扰。该方法在建筑材料中有毒有害组分的分析检测方面有一定的应用价值。

煤-焦炉气共热解特性研究Ⅳ.甲烷和一氧化碳对热解的影响

分别在具有不同Ｈ２、ＣＨ４、ＣＯ等气体组成的热解反应气气氛下，采用１０ｇ固定床反应器考察了先锋褐煤热解产品收率的变化规律，并利用日本ＳＨＩＭＡＤＺＵＧＣ１７Ａ／ＱＰ５０００ＭＳ对焦油进行色质联检。结果表明：焦炉气中甲烷和一氧化碳对加氢热解有十分重要的作用，二者相互促进相互制约共同影响热解结果。其中甲烷对加氢热解的影响具有双重性，一方面它能提高焦油收率（特别是在较高压力下），同时能明显增加焦油中苯、甲苯、二甲苯（ＢＴＸ）和萘的相对含量，实现焦油轻质化；另一方面它又降低热解总转化率（半焦收率增加）并生成更多的热解水分。焦炉煤气中的一氧化碳也有利于提高热解总转化率、焦油收率并主要通过增加酚、甲酚、二甲酚（ＰＣＸ）的含量以改善焦油质量，但它却促进了水的生成。相比较而言，焦炉煤气中甲烷对增加热解焦油产率和改善焦油质量比一氧化碳具有更为明显的影响。

煤-焦炉气共热解特性的研究Ⅰ.固定床热解反应特性

在１０ｇ固定床反应器中对先锋褐煤在焦炉气气氛下的热解特性及有关工艺参数，如反应压力、升温速率等的影响进行了详细考察，并与其同等条件下的加氢热解特性进行了对比分析。实验结果表明，在反应压力５ＭＰａ、升温速率５Ｋ／ｍｉｎ，终态温度９２３Ｋ条件下，先锋褐煤在焦炉气气氛下的热解转化率为５９．０％（ｄａｆ），焦油收率达３５．８％（ｄａｆ）。与同等条件下的纯氢气氛（３ＭＰａ）相比，转化率降低了约７％（ｄａｆ），而焦油收率提高了约７％（ｄａｆ）。这说明焦炉气中的诸如甲烷等其它组分的存在对煤的热解行为有重要作用。由于煤加氢热解受传质影响，因此不同工艺参数对热解反应影响很大，较高压力下的慢速升温有利于提高转化率和油品收率；升温速率对油品收率影响较为明显，慢速升温有利于提高油品收率。

煤-焦炉气共热解热重研究Ⅱ.热解半焦燃烧反应性

采用高压热天平在终态温度为８００℃，压力为０．１～５ＭＰａ，升温速率为５～２５℃／ｍｉｎ的实验条件下，对先锋、黄县褐煤和兖州烟煤在真实焦炉气气氛中共热解特性进行了系统的ＴＧ／ＤＴＧ研究，主要考察了反应压力、升温速率对热解特性的影响，并与可比条件下加氢热解作比较。结果表明，压力和升温速率对热解有较大影响，压力升高热解总失重量增加，升温速率减慢有利于提高热解总转化率；压力与升温速率互相促进又互相制约共同影响热解特性。在给定较高压力下，减慢升温速率能明显提高热解总转化率；在慢速升温条件下，提高压力也能明显提高热解总转化率，通过降低升温速率可以实现在较低压力下达到甚至超过高压下的热解效果。与可比条件下的加氢热解相比，煤焦炉气共热解具有相近的热解特性，但总转化率略有降低且失重峰温向高温区移动。

Factors controlling the enrichment of natural gas in Kuche depression,Tarim Basin,NW China:Molecular geochemical evidence from sedimentary organic matter

Using molecular geochemical data from infrared spectrometer and pyrolysis gas chromatography-mass spectrometry, this paper investigates the petroleum generation characteristics of Jurassic coal measures from Kuche depression, Tarim Basin, NW China. The results showed that the Jurassic coaly rocks with medium maturity (R0%: 0.8-1.1) were enriched in gas-prone functionalities (-CH3) and low molecular weight pyrolysates (【nC21), indicating that the coaly rocks from Kuche depression were gas/condensate prone at the stages of middle to high maturation, and it was further supported by the oil/source correlation from well Yinan 2 in this region.