The physical character of coal char formed during rapid pyrolysis at high pressure

Rapid pyrolysis was conducted in a drop tube reactor using seven coals under various operating conditions. In addition to dense char, porous chars (network char and cenospheric char) were formed by the rapid pyrolysis under certain conditions. Porous char was mainly composed of film-like carbon and skeleton carbon. The pyrolyzed coal char particles were characterized in detail. Morphology and bulk density of porous char were quite different from the dense char formed under the same conditions, but elemental composition and BET surface area were similar to each other. CO₂ gasification reactivity of porous char was lower than dense char in the later gasification stage, and this was ascribed to the low reactivity of skeleton carbon.     

改性聚磷酸铵对三嗪类膨胀阻燃聚丙烯性能的影响

由改性聚磷酸铵(APP)、自制的三嗪类成炭发泡剂(CFA)等复配制成膨胀型阻燃剂(IFR),以二氧化硅、二氧化钛等为协效剂阻燃聚丙烯(PP)。研究了不同组分的IFR及协效剂对阻燃PP复合材料阻燃性能、力学性能和耐水性能的影响。结果表明:改性APP的亲水性下降;由改性APP/CFA(4/1)、二氧化硅协效剂复配的PP复合材料阻燃性能、力学性能优良,助剂在PP基体中分散性好,热水浸泡后氧指数为32.5%,仍能达到UL94V—1级,失重率为2.92%。     

Carbon particle type characterization of the carbon behaviour impacting on a commercial-scale Sasol-Lurgi FBDB gasifier

Char-form analysis, whilst not yet an ISO standard, is a relatively common characterization method applied to pulverized coal samples used by power utilities globally. Fixed-bed gasification coal feeds differ from pulverized fuel combustion feeds by nature of the initial particle size (+6 mm, −75 mm). Hence it is unlikely that combustion char morphological characterization schemes can be directly applied to fixed-bed gasifier chars. In this study, a unique carbon particle type analysis was developed to characterize the physical (and inferred chemical) changes occurring in the particles during gasification based on coal petrography and combustion char morphology. A range of samples sequentially sampled from a quenched commercial-scale Sasol-Lurgi fixed-bed dry-bottom (FBDB) Gasifier were thus analysed.It was determined that maceral type (specifically vitrinite and inertinite) plays a pivotal role in the changes experienced by carbon particles when exposed to increasing temperature within the gasifier. Whole vitrinite particles and vitrinite bands within particles devolatilized first, followed at higher temperatures by reactive inertinite types. By the end of the pyrolysis zone, all the coal particles were converted to char, becoming consumed in the oxidation/combustion zone as the charge further descended within the gasifier.The carbon particle type results showed that both the porous and carbominerite char types follow similar burn-out profiles. These char types formed in the slower pyrolysis region within the pyrolysis zone, increasing to around 10% by volume within the reduction zone, where 53% carbon conversion occurred. Both of these char forms were consumed by the time the charge reached the ash-grate at the base of the reactor, and therefore did not contribute to the carbon loss in the ash discharge. It would appear as if the dense char and intermediate char types are responsible for the few percent carbon loss that is consistently obtained at the gasification operations.The carbon particle type analysis developed for coarse coal to the gasification process was shown to provide a significant insight into the behaviour of the carbon particles during gasification, both as a stand alone analysis and in conjunction with the other chemical and physical analyses performed on the fixed-bed gasifier samples.     

Experimental trends of NO in circulating fluidized bed combustion

Experimental trends for the dependence of CO, NO and N₂O emissions on bed temperature and oxygen concentration in circulating fluidized bed combustion (CFB) are presented. The main focus is on the nitrogen emission formation in the lower furnace area. A test campaign including seven tests with a laboratory scale CFB test rig were carried out to produce appropriate data of the phenomena. These experiments show that NO emissions above the dense bed decrease with decreasing temperature or oxygen concentration. Instead, N₂O emissions increase when the bed temperature is decreased and decrease when the oxygen concentration is decreased. These trends can partly be explained by heterogeneous reactions between NO and char, since decrease in temperature or oxygen concentration increases the bed char inventory. However, oxygen and temperature also affect directly on NO emissions. Correlations for the CO, NO, N₂O, NH₃ and HCN concentrations at the exit of dense bed were developed. This type of correlations can, among other things, be applied as boundary conditions to the more sophisticated CFD models that are usually applied to modelling of diluted part of the furnace. CFD modelling of the dense bed area is complicated and accuracy is not sufficient, thus simplified experimental correlations can aid in the development of furnace design towards better emission performance.     

堵水酸化一体管柱技术的研究应用

随着青海油田开发的不断深入,油田开发逐步走向精细化,在开发过程中不断采用先进的采油工艺技术成为油田开发的主旋律。堵水酸化一体管柱技术通过一趟管柱在完成对油井出水层的封堵的同时能够对产油层进行分层酸化,不但减少了施工强度、降低了作业费用而且能够缩短油井投产时间。     

非API油井管技术在中国石化四川天然气勘探区块的应用

介绍了中国石化四川天然气勘探区块在完井工程所遇到的油井管技术难题,主要体现在海相气井油层套管设计和高温高压含CO2气井油套管材质选择两个方面。针对高强度与抗硫能力要求之间的矛盾,采取了组合套管解决方案。针对存在CO2腐蚀的气井井筒安全经济设计的技术难题,对于腐蚀极严重的情况,采取了生产管柱和封隔器预座封段选用HP1-13Cr非API油井管柱的解决方案;而对于腐蚀较轻的情况,采取了普通材质油井管+特殊螺纹+封隔器完井的解决方案。上述技术方案已在井场得到成功应用。     

抽油机井抽油杆柱瞬态力学行为有限元分析方法

抽油杆柱是一个超细长的大柔性杆,其运动的力学行为是几何非线性、接触非线性和动力学的耦合问题.将几何非线性、接触非线性和动力学有机地结合起来,运用有限元方法,精确地描述了抽油杆柱在充满井液的油管内往复运动的力学行为,找出了其屈曲、杆管接触和磨损的变化规律,为防止油杆柱断脱和油管漏失事故提供了理论依据.     

Change of chemical bonding of nitrogen of polymeric N-heterocyclic compounds during pyrolysis

Pyrolysis experiments were carried out with polymeric model compounds containing defined forms of bound nitrogen. The chosen compounds, polyvinylcarbazole, polyvinylpyridine and polyvinylpyrrolidone, were pyrolysed in a fixed bed annular reactor at 873 and 1173 K. The functionalities of the nitrogen in the precursors as well as that in the derived chars were determined by X-ray photoelectron spectroscopy (XPS). Additional information about the structure was received from FT-IR, solid-state ¹³C-NMR and, in part, X-ray absorption near edge structure (XANES) spectroscopy. The application of different analytical methods should result in a more reliable classification of the N 1s electron binding energies than is possible by the sole use of XPS. It is interesting to note that the nitrogen in five-membered rings (N-5) of the N-heterocyclic compounds remains in existence in the high temperature products. In the case of the carbazole system it is still the dominant bonding form. The high-temperature char from polyvinylpyridine contains nitrogen in both five- and six-membered rings. It may be concluded that the behaviour of the nitrogen during pyrolysis does not only depend on its functionality but also on its chemical environment. A comprehensible mechanism of the transformation of N-6 into N-5 nitrogen is discussed on the basis of the FT-IR and solid-state ¹³C-NMR spectra of the low temperature chars.     

基于串热源及CCT图的GMAW焊接热影响区组织及硬度预测

将熔化极气体保护焊（GMAW）的热输入处理为三维移动串热源,建立了串热源模型,模拟了JG590低合金钢的GMAW焊接热过程,进行了JG590钢的GMAW焊接工艺实验,通过焊缝横截面熔合线的几何形状以及焊接接头的几何尺寸对所建模型进行了实验验证,分析评价了目前常用的ts／5计算公式,利用JG590钢GMAW焊接热过程的模拟结果,结合其连续冷却组织转变图（CCT图）,成功预测了焊接热影响区（HAZ）的组织及硬度．     

Effects of CO Atmosphere on the Pyrolysis of a Typical Lignite

To reveal the effect mechanism of CO atmosphere on coal pyrolysis, a study on raw and demineralized lignite was carried out in a horizontal tube furnace under N₂ and CO/N₂ atmosphere. CO had a negligible effect on the char yield at low temperatures, whereas it enhances the char yield at temperatures higher than 550 °C. The release of tar was higher in the presence of CO above 450 °C because of more free radicals, which reduced low‐temperature crosslinking, and higher selectivity of hydroxyl groups to phenols in the CO‐containing atmosphere. The yields of CO₂ and H₂ increased, water and CO yields decreased under CO/N₂ atmosphere. Light hydrocarbon gases were not affected by changing the reaction atmosphere. The difference between product yields from raw and demineralized coal confirmed that the catalysis of inherent minerals had a great catalytic effect on the water‐gas shift reaction and Boudouard reaction.