Carbonization and liquid-crystal (mesophase) development. 15. A common stage in mechanisms of coal liquefaction and of coal blends for coke making

This paper discusses the processes of coal liquefaction and co-carbonization of coal/pitch blends in terms of physical and chemical properties of the fluid phases found in both pyrolysis systems. Mechanisms of development of thermal plasticity in coals are outlined. In coal liqudfaction the importance is stressed of hydrogen-donor vehicles interacting with the products of thermal depolymerization of coal. The concept of variations in the facility of solvation and solvolysis of additives in co-carbonizations can explain the variations observed in degrees of interaction of a single coal with several additives. Possibly, the hydrogen-donor facility of an additive may be as important in assessments of modifying ability as an average molecular structure. The possibility exists of using an analysis of optical texture of cokes resulting from the fluid coal/solvent pyrolysis systems to characterize the effectiveness of solvents in coal liquefaction systems as distinct from coal blending co-carbonization studies.     

Carbonization and liquid-crystal (mesophase) development. 8. The co-carbonization of coals with acenaphthylene and decacyclene

Several coals of different rank have been carbonized singly and also co-carbonized with acenaphthylene and decacyclene. The resultant cokes were mounted in resin and polished surfaces were examined for optical texture using a polarized-light optical microscope fitted with a half-wave retarder plate. The optical texture can be assessed qualitatively (visually) or quantitatively by a point-counting technique in terms of size and shape of constituent isochromatic anisotropic units. Some cokes from coals were Isotropic. Acenaphthylene was only able to exert a smaller influence than decacyclene on the optical texture of the resultant cokes from co-carbonizations. Decacyclene was able to modify the optical texture for both the low-rank non-fusible and the caking coals. The effects of changing the proportions of coal to additive were examined. Results are interpreted in terms of ‘depolymerization’ of the coal by the action of the additive (as solvent) and also by the action of the additive in modifying the processes of formation of semi-coke via nematic liquid crystals.     

Composition and properties of SS coal

SS coal, predominantly from open-pit mines, is regarded as an oxidized analog of valuable (KO, K, OS) isometamorphic coals from underground mines. The options for modifying SS coal are discussed.     

溶剂效应对脱除煤沥青中3,4-苯并芘的影响

研究了单种溶剂、混合溶剂对3,4-苯并芘的溶解选择性及煤沥青溶解量。并以顺丁烯二酸酐为改性剂、硫酸为催化剂,考察了溶剂效应对降低煤沥青中3,4-苯并芘的影响。研究表明,环己烷、甲苯,环己烷、乙酸丁酯组成的混合溶剂具有较好的3,4-苯并芘溶解选择性和合适的煤沥青溶解量。当环己烷∶甲苯=2∶1（体积比）和环己烷∶乙酸丁酯=2∶1（体积比）为反应溶剂时,能够高效地脱除煤沥青中3,4-苯并芘,煤沥青中3,4-苯并芘降低率分别达到88.26%和90.83%。其原因认为是此类溶剂能使包裹在沥青颗粒内部的3,4-苯并芘释放出来,且3,4-苯并芘与改性剂能够形成均相反应体系,大部分不具有致癌性的高相对分子质量环芳烃与改性剂之间形成两相体系,从而提高了改性剂与3,4-苯并芘的有效反应。     

Solvent-refined coal from high-ash non-coking coals and washery middlings for use in metallurgical coke making Part 1. Production,testing and characterisation

This paper presents studies on the preparation of a potential coking additive, solvent-refined coal (SRC), from typical high-ash Indian non-coking bituminous coals, tertiary Assam coal with a high sulphur content and washery middlings in a bench-scale unit (10 kg h⁻¹ coal throughput capacity) under hydrogen pressure. The extraction of the coal samples was conducted under moderate reaction conditions of temperature, pressure and residence time. No external catalyst was used in the process. Pre-beneficiated coal was used as the feed material and anthracene oil with a boiling range of 270–360°C was used as the solvent. Rigorous solid separation from the extract slurry by filtration was avoided by centrifugation in a super-decanter centrifuge to produce SRC with an ash content of 6–7%. The yield of SRC from non-coking Samla seam coal of the Raniganj coalfield was found to be 85% while its caking index was 44. Substantial improvement in the quality of blast furnace-grade coke was achieved by co-carbonisation of coking blends by mixing only 10% of the SRC prepared from Assam coal. The hydrogen requirement was low (1.5% wt/wt of d.a.f. coal) and recovery was of the order of 96% of the solvent used for the preparation of the coal-oil slurry. The yield of SRC and its quality as a coking agent are reported, along with the quality of the coke produced using SRC obtained from typical coal.     

Effect of coal extracted with NMP on its aggregation

Tow-step extraction of Upper Freeport (UF) coal, i.e. exhaustive extraction with N-methyl-2-pyrrolidinone (NMP) solvent and subsequent extraction with the CS2/NMP mixed solvent (1:1 by volume) with or without additive was compared with the direct extraction of UF coal with the CS2/NMP mixed solvent (1:1 by volume) with or without additive. It was found that there is almost no difference of extraction yields between the two-step extraction and direct extraction with or without additive. The result show that NMP can only give external extraction to extract the outside fractions of coal particles, and this will not cause the new aggregation formed in the coal molecules. The interactions between coal molecule and additive are responsible for the extraction yield enhancement by additive.     

Impact of calcium chloride addition on mercury transformations and control in coal flue gas

Pilot-scale experiments were conducted to investigate mercury transformations in coal flue gas when firing subbituminous coal with a CaCl₂ additive. Cofiring the CaCl₂ additive with the subbituminous coal resulted in approximately 50% oxidized mercury, as a result of reactive chlorine species formed in coal flue gas, compared to the dominance of elemental mercury in the baseline flue gas. The mercury data indicate that mercury-flue gas chemistry reactions may occur at fairly high temperatures (>400 °C) in chlorine-enriched flue gas. Field tests were conducted to further demonstrate the impact of cofiring CaCl₂ on the eventual fate of mercury. These tests were completed on a 650-MW subbituminous coal-fired power plant equipped with selective catalytic reduction (SCR), a fabric filter (FF), and a wet scrubber. Overall mercury removals across the SCR-FF-wet scrubber system ranged from 75% to 96% with 200-800 ppm (coal basis) chlorine addition compared to 18-32% during baseline operations. Field data indicate that the SCR enhanced mercury oxidation, possibly as a result of the supplemental formation of reactive chlorine species and the aid of the SCR catalyst. As a result, most of the mercury in the flue gas was in an oxidized state and was removed in the downstream wet scrubber, indicating that cofiring CaCl₂ is an effective mercury control approach for a subbituminous coal-fired plant equipped with an SCR and wet scrubber.     

Effect of air oxidation on coal hydrogenation

Japanese Taiheiyo coal (75.9%C) was oxidized with air at 250 °C for 3–40 h and at 300 °C for 3–10 h. The weight decreased from 16.3 to 46.5% at 250 °C and from 21.7 to 41.3% at 300 °C. Carbon loss and yield of NaOH soluble were obtained. The resultant oxidation products were hydrogenated at 370 °C for 1 h under 10 MPa hydrogen pressure using red mud with sulphur as catalyst and wash oil as solvent. Conversion to pyridine, benzene and n-hexane soluble fraction shows a minimum for the coal oxidized 10 h at 250 °C and for the coal oxidized for 3 h at 300 °C. Initial oxidation makes a network structure which contributes to a reduction in conversion, but in later stages of oxidation, splitting of bridge linkages and/or ring opening of aromatic structures, contribute to increases in conversion.     

呼伦贝尔褐煤溶剂萃取及萃余煤的双氧水氧化产物分析

以CS2、乙醇和丙酮作为溶剂,对呼伦贝尔褐煤进行连续萃取,并利用气相色谱/质谱联用(GC/MS)技术对萃取物进行分析。结果表明:CS2萃取物主要由长链脂肪烃和芳烃组成,而这些脂肪烃存在于3种溶剂萃取物中。在40℃条件下,用H2O2溶液采用恒温水浴和超声两种方式氧化萃余煤,超声条件下氧化剧烈,并用FTIR分析了原煤、萃余煤、氧化煤的化学结构的变化。氧化后的水溶物用乙酸乙酯萃取后,用GC/MS检测萃取物,恒温水浴氧化可以检测到30种化合物,而超声氧化只检测到14种,且都是以酯类为主。     

铁系催化剂对煤高温快速液化的影响

以兖州煤为研究对象,采用微型反应釜研究了两种铁系催化剂对煤高温快速液化的影响.结果表明,担载Fe2S3的催化剂和高分散铁系催化剂对煤的热解行为影响较小;担载Fe2S3催化剂促进了氢气参与反应和煤液化产物向轻质化转化,在优秀和足量的供氢溶剂条件下,溶剂的供氢速度明显优于氢气转换的供氢速度,催化剂的作用不明显;对比添加高分散铁系催化剂并加助剂S和添加Fe2S3催化剂的煤高温快速液化,发现元素S的作用与S和主催化剂铁的结合形态有关.     

Carbonization of an anthracene oil extract of Akabira (Japan) coal

The carbonization of a non-hydrogenated extract (STC) from a low-rank coal (C, 83 wt%) of high fluidity was studied as single carbonizations and as co-carbonizations with additives, an objective being the production of needle-coke. The coke from STC had an optical texture of fine-grained mozaics; however, fractionation followed by co-carbonizations were effective in modifying carbonization properties. The lighter fraction of STC could give a coke with flow texture but in reduced yield. The addition of hydrogenated Ashland A240 pitch (HA240) in a quantity as low as 20% could effectively modify the carbonization properties of STC. A novel co-carbonization, in which an additive such as dihydroanthracene is recovered at the latter stage of the carbonization in the dehydrogenated form, was found to be effective also, although a relatively large amount of the additive was required. Among the non-hydrogenated additives, Ashland A240 pitch was the most effective in modifying the STC. The cocarbonization of fractionated STC reduced the quantity of additive required while maintaining a reasonable coke yield. Some practical aspects for the production of needle-coke from STC are discussed.     

Optimal preparation of oxidized coal

The oxidation index is an important characteristic of coal and coal batch, indicating the change in coking properties on oxidation. The coke obtained from coal batch containing poorly clinkering oxidized coal has a higher content of isotropic carbon and a lower content of anisotropic carbon. That explains its increased reactivity and impaired mechanical and postreactive strength. The oxidation on storage is greatest for small coal classes (<0.5 mm). Preliminary removal of <0.5 mm oxidized coal markedly improves the reactivity and also the mechanical and postreactive strength. A method of preparing oxidized coal for coking is proposed: finer grinding (until the content of the ≤1 mm class is 100%). That considerably reduces the influence of the oxidized coal on the quality of the coke produced.     

高速逆流色谱分离纯化氧化葵花油中三亚油酸甘油酯单氢过氧化物

该文为了获得较高纯度的三亚油酸甘油酯单氢过氧化物,用于"脂肪调控氧化-热反应"制备肉味香精机理的研究。葵花油在70℃下通空气0.72 m3/(kg.h)氧化70 h制备含三亚油酸甘油酯单氢过氧化物的氧化产物,采用液-质联机定性及液相色谱-蒸发光散射检测器面积归一化定量,氧化产物中三亚油酸甘油酯单氢过氧化物质量分数为1.95%。高速逆流色谱分离该氧化产物中的三亚油酸甘油酯单氢过氧化物,较佳的两相溶剂系统为V(正己烷)∶V(二氯甲烷)∶V(乙腈)=4∶1∶3。以上相为固定相,下相为流动相,正向洗脱,流速1.5 mL/min,转速850 r/min,上样5 g,分离时间195 min,一次性得三亚油酸甘油酯单氢过氧化物53 mg,液相色谱-蒸发光散射检测器分析纯度为96.3%,回收率52.3%。     

In-vitro assay for mutagenic activity and gas chromatographic-mass spectral analysis of coal liquefaction material and the products resulting from its hydrogenation

Employing assays for microbial mutagenesis activity together with solvent fractionation and gas chromatographic-mass spectral analysis, coal liquefaction material was compared to its catalytically hydrogenated products with regard to biological activity and chemical composition. The mutagenic activity of the moderate and severly hydrogenated products was substantially reduced compared to that of the feedstock. In contrast to the essentially aromatic nature of the principal components in the coal oil feedstock, the hydrogenated products were shown to contain mainly hydroaromatic species with a significant decrease in the fraction of basic and tar components as obtained by our acid-base solvent separation procedure. Subfractions of the basic and tar components obtained from the feedstock were shown to contain primary aromatic amines, the concentrations of which were essentially in direct proportion to the observed microbial mutagenic activity. No primary aromatic amines were detected in the hydrogenated products. Hydrotreating appears to produce a coalderived liquid with far less mutagenic activity than the untreated coal liquefaction material.     

Multiple mechanisms for the loss of coking properties caused by mild air oxidation

Evidence is presented for the existence of at least three different mechanisms by which low temperature oxidation (weathering) destroys coal's coking properties. Lithium aluminium hydride reduction of Bruceton coal oxidized for 28 days restores the FSI to its initial value of 8 from a value of 3. After 220 days oxidation, reduction raises the FSI from 0.5 to 2. Clearly, two different processes are responsible for the FSI decrease. The pyridine solvent swelling change during this time is quite small, much smaller than observed by Liotta. Thus the oxidative increase in cross-link density observed by Liotta is a third mechanism of thermoplasticity loss. The initial FSI decrease, that reversible by reduction, is tentatively ascribed to oxidative loss of readily donatable hydrogen from the coal. The second mechanism remains uncharacterized.     

Coal liquefaction using a hydrogenated creosote oil solvent: H-atom transfer from hydrogen donor components in the solvent

The presence of hydroaromatic, hydrogen donor components in a coal-derived solvent is one of the more important factors in the successful operation of a non-catalytic coal liquefaction process. Various hydrogen donor species present in a hydrogenated creosote oil have been identified. Their rate of disappearance under conditions that are consistent with a short residence time coal liquefaction process has been used to rank the reactivities of the various hydrogen donors. 1,2,3,10b-Tetrahydrofluoranthene was found to be an exceptional donor while 4,5-dihydropyrene, the hexahydropyrenes and 9,10-dihydrophenanthrene were found to be quite active. Sym.-octahydrophenanthrene and 2a,3,4,5-tetrahydroacenaphthene exhibited moderate activity. Tetralin and the four methyltetralin isomers were found to be unreactive under the coal liquefaction conditions employed.     

泥炭腐植酸类物质在洁净煤技术中的应用

介绍了泥炭腐植酸类物质用作水煤浆添加剂和型煤粘结剂的理论基础和实际应用效果。结果表明,将泥炭中含有的大量腐植酸类物质经过改性,用作水煤浆添加剂,在新汶煤、八一煤、邢台煤、兖州煤、鹤岗煤、抚顺煤、神华煤、双鸭山煤等煤种上使用,制浆浓度在65%～69%,粘度在1000mPa·s左右;用作型煤粘结剂,添加量在7%～10%,单个球的冷强度为55～88kg,热强度为50～70kg,常温下耐水性好,对灰分无增加,对环境无污染。     

Modifying ability of Ql-free coal-tar pitch to develop optical anisotropy in co-carbonizations

Carbonization properties of a Ql-free coal-tar pitch (CTP-ASM) prepared by selective precipitation were studied to evaluate it as a source for needle-coke. Its modifying ability for production of needlecoke in co-carbonizations with principal carbonizing substances which gave cokes of mozaic texture in single carbonizations was estimated by changing mixing ratios. The shape and size of the anisotropic optical texture in the co-carbonized coke were measured by point counting. CTP-ASM and Ashland A240, of eight additives, had the highest modifying ability in the co-carbonizations with Khafji vacuum residue. Both contained ca. 6% benzene-insolubles (Bl), and had f_a values of ≈0.9. Other additives of either lower or higher Bl or f_a showed less modifying ability. The modifying susceptibility of principal carbonizing substances varies with their structure and properties. Based on a systematic investigation of co-carbonizations the compatibility between a principal carbonizing substance and an additive is discussed from a viewpoint of their structural parameters.     

Electrochemical promotion of IrO2 catalyst activity for the gas phase combustion of ethylene

The catalytic activity for the gas phase combustion of ethylene of an IrO2 film, used as electrode in a solid electrolyte cell, can be increased by polarizing the metal–solid electrolyte interface. The catalytic activity remains higher even after current interruption. To explain the increase in the open circuit rate after polarization we speculate that the IrO2 catalyst is oxidized at the catalyst–solid electrolyte interface, forming IrO2+delta, which is transported by surface and/or bulk diffusion to the gas exposed catalyst, thus modifying its catalytic activity.     

聚乙二醇改性脱除煤沥青中3,4-苯并芘

以聚乙二醇为改性剂,研究在溶剂条件下降低煤沥青中3,4-苯并芘的工艺。研究表明,当混合溶剂V环己烷∶V甲苯=2∶1为反应溶剂、硫酸用量为煤沥青质量的6.67%、聚乙二醇600用量为煤沥青质量的10%、反应温度为80℃、反应时间为5h时,3,4-苯并芘降低率为85.59%。