Thermodynamic evaluation of integrated gasification combined cycle: Comparison between high‐ash and low‐ash coals

In the present study, a coal‐integrated gasification combined cycle power plant is simulated. A high‐ash coal and low‐ash coal are considered to compare the performance of the plant. The combined cycle is in typical commercial size with 450 MW capacity. The feeds are Tabas and Illinois #6 coals which approximately contain more than 30% and 10% ash and have higher heating values of 22.7 MJ/kg and 26.8 MJ/kg, respectively. Energy and exergy analyses are done by aspen plus ^® and ees , respectively. Energy analysis shows that the overall efficiencies of power plants using high‐ash and low‐ash coals are 33% and 28%, respectively. The result shows that in high‐ash case, 52 kg/s coal, 10 kg/s water, and 1050 kg/s air and in low‐ash case, 48 kg/s coal and 820 kg/s air are required for providing mentioned power, approximately. Exergy analysis shows that maximum exergy destruction is in heat recovery steam generator unit. Investigating the emissions shows that high percent of ash in the coal composition has slight effects on the IGCC pollution. Finally, from thermodynamic viewpoint, it is concluded that the high‐ash coal, like the conventional one, can be used as thermally efficient and environmentally compatible feed of IGCCs. Copyright © 2016 John Wiley & Sons, Ltd.     

Comparison study on different ITM‐integrated MCFC hybrid systems with CO2 recovery using sweep gas

Previous study shows the ITM (oxygen ion transfer membrane)‐integrated MCFC (molten carbonate fuel cell) hybrid system with CO₂ recovery can maintain high efficiency; however, the oxygen partial pressure on the ITM permeate side is usually 1 atm, which requires a very high pressure ratio of the ITM air compressor in order to separate the oxygen; using the sweep gas can solve this problem. In this paper the ITM‐integrated MCFC hybrid systems with CO₂ recovery using different sweep gases are studied. With the Aspen plus software, two systems with different sweep gases are established, and their performances are compared with the benchmark system without sweep gas; the effects of key parameters on the optimum system performance are also investigated. Results show that compared with the benchmark system, the efficiencies of the systems with sweep gases are increased and the pressure ratios of the air compressors are decreased; the system using pure CO₂ as sweep gas can improve the system efficiency by 1.25%, which is superior to the system using the mixture gas of CO₂ and H₂O as sweep gas. Achievements from this paper will provide a valuable reference for CO₂ recovery from the MCFC hybrid power system with lower energy consumption. Copyright © 2016 John Wiley & Sons, Ltd.     

化学预浸渍次数对沙柳P-RC APMP木素结构的影响

以沙柳为原料生产盘磨化学预处理碱性过氧化氢机械浆( P-RC APMP),在NaOH总用量8％、H2O2总用量10％时,研究沙柳原料木素(SPL)、单次化学预浸渍的沙柳P-RC APMP中木素(1-PL)和2次化学预浸渍的沙柳P-RC APMP中木素(2-PL)的变化.与SPL总量相比,1-PL和2-PL的总量分别减少8.3％和14.3％;与SPL相比,1-PL和2-PL中的脂肪族羟基含量基本没有变化,但总酚羟基(Tp-OH)含量分别降低了44.2％和47.1％;与SPL相比,1-PL和2-PL的数均分子质量和质均分子质量均逐渐减小,但两者的多分散性逐渐增加.     

化机浆性能的优化——添加同种低游离度化机浆对成纸性能的影响

用PFI磨制备低游离度的杨木P-RC APMP,并将其添加到高游离度杨木P-RC APMP中获得混合浆,然后对混合浆成纸性能进行研究。首先研究了低游离度浆添加量对混合浆性能的影响,结果表明,随低游离度浆添加量的增加,纸张松厚度变化率下降,内结合强度变化率上升,抗张指数变化率先增加后降低且在添加量超过25%时达到最大值。这表明在高游离度浆中添加一定量的低游离度浆能改善混合浆成纸的强度性能。与未添加低游离度浆的浆料相比,当低游离度浆添加量为20%时,混合浆成纸松厚度得到改善,且强度性能相当。光学显微镜分析表明,随低游离度浆添加量的增加,丝状细小纤维是混合浆成纸强度性能提高的一个原因;SEM图与孔径分布研究表明,添加低游离度浆后,细小纤维能有效留在纸张中,填充在粗纤维孔隙中,进而提高纸张强度。     

竹沥液对粉单竹APMP木素发色基团的影响

从粉单竹中提取竹沥液,探讨了竹沥液对粉单竹磨木木素、粉单竹未漂及漂后APMP磨木木素发色基团的影响,并采用紫外光谱和红外光谱分析木素发色基团的变化。结果表明,竹沥液中含有发色基团,且竹沥液会吸附在木素上,从而增加木素共轭羰基的含量;经紫外光照射后,木素及吸附在其表面的竹沥液会生成新的发色基团,进而影响粉单竹APMP的白度和返黄程度。     

阴离子垃圾捕集剂对APMP浆成纸性能的影响

探讨聚乙烯亚胺(PEI)和聚合氯化铝(PAC)两种阴离子垃圾捕集剂对APMP浆阳离子需求量的影响,并研究APMP浆配抄文化用纸过程中,两种阴离子垃圾捕集剂与成纸施胶度、抗张指数、撕裂指数、耐破指数和内聚力等物理性能之间的关系。结果表明:PEI和PAC是两种有效的ATC,可有效中和阴离子垃圾的负电荷,但也有一部分被带负电的纤维所吸附。相对而言,PEI的使用效果明显优于PAC,PEI的用量以0.1%～0.2%为宜。PEI和PAC的使用可显著提高AKD的施胶效果,同时在一定程度上改善了纸张的抗张指数、耐破指数、撕裂指数和内聚力。其中,PEI对纸张施胶度和内聚力的改善效果要明显优于PAC,在其他三个强度指标上优势不明显。     

不同工艺流程对沙柳P-RC APMP浆料性能的影响

采用沙柳为原料生产高得率碱性H2O2化学机械浆,发现在NaOH总用量为8%,H2O2总用量为10%时,和沙柳单段P-RC APMP浆料相比,沙柳双段P-RC APMP浆料的白度增加8.34%,裂断长增加21.82%,耐破指数增加24.83%;浆料内的细小纤维较沙柳单段P-RC APMP中的细小纤维多,纤维表面的碎片较多,纤维分丝帚化的程度较大;纤维的结晶度降低了3.45%。     

预浸渍对沙柳两段P-RC APMP浆料性能的影响

研究了预浸渍化学药品NaOH和H2O2的用量对沙柳两段P-RCAPMP浆料性能的影响。结果表明:NaOH和H2O2用量分别是影响沙柳两段P-RCAPMP强度性能和白度的主要因素,NaOH最佳总用量为8%,H2O2的最佳总用量为10%;当第一段浸渍时NaOH和H2O2用量比大于1,二段化学浸渍NaOH和H2O2用量比一般小于1时,浆料的强度和白度都能得到最佳效果。     

桉木化机浆生产工艺实践及优化

介绍了以桉木(45%～70%)为原料,生产化机浆的P-RCAPMP生产线的工艺、成品浆特点、常见故障及处理措施。该生产线采用一段预浸、两段磨浆和两段漂白,生产出了白度50%～82%ISO、游离度200～350mlCSF,松厚度≥2.2cm3/g的桉木化机浆,主要用于配抄轻型纸、白卡纸、口杯纸、书写纸、静电复印纸和双胶纸等。     

杨木APMP制浆废水污染物成因及规律研究

研究了杨木APMP不同制浆条件下,杨木各化学组分溶出的变化对制浆废水污染物发生量的影响。固定NaOH用量为4%,H2O2用量由1%增加至3%时,认为苯醇抽出物对污染物负荷贡献最大。H2O2用量由4%增加至6%时认为木素对污染物负荷贡献最大。此外,建立了H2O2用量、制浆得率和纸浆白度与CODCr、BOD5发生量之间相关数学表达式,通过对这些影响因子和数学表达式的相关系数进行优化,可以通过H2O2用量(%)来对漂白废水中污染物负荷进行测算。