Challenges and Opportunities of Modeling Biomass Gasification in Aspen Plus: A Review

Aspen Plus has become one of the most common process simulation tools for both academia and industrial applications. In the last decade, the number of the papers on Aspen Plus modeling of biomass gasification has significantly increased. This review focuses on recent developments and studies on modeling biomass gasification in Aspen Plus including key aspects such as tar formation and model validation. Accordingly, challenges in modeling due to specific assumptions and limitations will be highlighted to provide a useful basis for researchers and end-users for further process modeling of biomass gasification in Aspen Plus.     

Modeling & optimization of renewable hydrogen production from biomass via anaerobic digestion & dry reformation

There is a growing interest in the usage of hydrogen as an environmentally cleaner form of energy for end users. However, hydrogen does not occur naturally and needs to be produced through energy intensive processes, such as steam reformation. In order to be truly renewable, hydrogen must be produced through processes that do not lead to direct or indirect carbon dioxide emissions. Dry reformation of methane is a route that consumes carbon dioxide to produce hydrogen. This work describes the production of hydrogen from biomass via anaerobic digestion of waste biomass and dry reformation of biogas. This process consumes carbon dioxide instead of releasing it and uses only renewable feed materials for hydrogen production. An end-to-end simulation of this process is developed primarily using Aspen HYSYS® and consists of steady state models for anaerobic digestion of biomass, dry reformation of biogas in a fixed-bed catalytic reactor containing Ni–Co/Al₂O₃ catalyst, and a custom-model for hydrogen separation using a hollow fibre membrane separator. A mixture-process variable design is used to simultaneously optimize feed composition and process conditions for the process. It is identified that if biogas containing 52 mol% methane, 38 mol% carbon dioxide, and 10 mol% water (or steam) is used for hydrogen production by dry reformation at a temperature of 837.5 °C and a pressure of 101.3 kPa; optimal values of 89.9% methane conversion, 99.99% carbon dioxide conversion and hydrogen selectivity 1.21 can be obtained.     

不同改良措施对排土场土壤微形态影响的试验研究

以铁矿排土场废石土为研究对象,自制模型试验装置,设计4种基质改良方法,开展SEM检测实验,并应用IPP软件对SEM照片进行定量化分析,研究在不同改良措施下对铁矿排土场土壤微结构的影响。结果表明：单施3%有机肥土壤孔隙度为16%,与对照组排土场原矿土相比增加了60%。复合施用3%有机肥、掺拌30%的黄土的处理孔隙度达到最大33%。单施3%有机肥、5%有机肥对土壤大团聚体含量皆有显著的促进作用,复合施有机肥、掺拌黄土的处理与单施有机肥的处理对比,土壤大团聚体含量增加并不显著。各改良措施的MWD与FMD均随着土壤中大团聚体的含量增加而增加。     

Simulation of integrated novel PSA/EHP/C process for high-pressure hydrogen recovery from Coke Oven Gas

This paper introduces a novel Coke Oven Gas (COG) hydrogen purification/compression system based on the technologies of Pressure Swing Adsorption (PSA) and Electrochemical Hydrogen Purification and Compression (EHP/C). As the EHP/C tolerates O₂, N₂ and CH₄ impurities, PSA can be utilized solely for CO and CO₂ removal (other COG impurities were not considered in this work). A relaxation of PSA hydrogen purity could significantly enhance its recovery rate. In this study, the suitability of traditional hydrogen PSA as part of the hybrid PSA/EHP/C approach was investigated. Aspen Adsorption and Matlab were used to model the PSA and EHP/C systems, respectively. The effect of adsorption pressure, purge-to-feed-ratio (P/F-ratio) and adsorption time within cycle on PSA performance is reported. This study found that breakthrough of non-detrimental components is typically accompanied with poisonous CO. Hence, the CO removal with traditional H₂-PSA resulted into high purity product. In a two-bed PSA, 36.3% of hydrogen was recovered at 99.9988% purity and 0.18 ppm CO. Subsequently, as a result, the EHP/C purification capability was merely utilized, but polished this hydrogen to >99.999% purity. Simultaneously, hydrogen was isothermally compressed to 20 MPa, consuming a marginal 2.42 kWh/kg. Compared to mechanical compression, this is 31.6% more energy efficient. Recovering hydrogen from by-product COG was found to save 0.5 kg CO₂/kg H₂ compared to hydrogen produced from natural gas. Conventional hydrogen PSA, utilizing 70% Activated Carbon and 30% Molecular Sieve 5A, was found not to be effective to target the removal of CO specifically. To increase synergy between PSA and EHP/C, the PSA requires adequate design and operation using appropriate adsorbents and cycle steps to target elimination of CO. An increased EHP/C catalyst tolerance for CO also contributes to higher flexibility.     

甲基氯硅烷精馏流程的模拟与优化

采用Aspen plus软件对工业七塔精馏过程进行全流程建模与模拟，优化工艺参数，研究了新的精馏节能工艺。对一甲塔等7个精馏塔采用双因素水平的灵敏度分析，考察了塔釜采出率、回流比、进料位置和塔顶压力对产品浓度和热负荷的影响，确定一甲塔最优的工艺参数：塔釜摩尔采出率为0.92，摩尔回流比为130，塔顶压力为0.18 MPa，总理论板数为400，在210块理论板位置进料。在此基础上，针对高能耗的脱高塔/脱低塔，模拟研究了双效精馏新工艺，新工艺可节省39.70%的年总成本；针对一甲塔模拟研究了热泵精馏新工艺，新工艺可降低41.42%的年总成本。     

新型硫酸法C_4烷基化工艺的模拟

提出了一种新型硫酸法C4烷基化生产工艺,丁烯原料在气相状态下进入反应器,与液相异丁烷、浓硫酸混合后,部分丁烯溶于液相,在液相中进行反应;通过控制反应器的压力,部分液相吸收反应热而汽化,使反应温度基本稳定;经气液分离、酸烃分离及产品分馏后,气相丁烯、异丁烷、浓硫酸分别构成循环。采用Aspen Plus过程模拟软件对新工艺过程进行模拟计算的结果表明,在反应器进口压力0.2 MPa、压降4.5 k Pa的条件下,反应器进出口温度均在7.2℃左右,可通过调节反应器压力实现温度的控制;反应器进口液相中烷烯质量比为145∶1,可减少副反应的发生;与传统硫酸法C4烷基化工艺相比,新工艺耗电量可降低30%。     

Hydrogen production potential from agricultural biomass in Punjab province of Pakistan

Depleting resources and popping environmental concerns instigate the development of sustainable and clean energy solutions. Amongst others, Hydrogen (H₂) is an imperious alternative due to the lowest emissions, higher calorific value, and usability. It has great relevance in Pakistan due to sequester Agricultural biomass potential that can be used as feedstock for H₂ production. So, this study estimates the H₂ production potential from agricultural biomass (rice, sugarcane, cotton, wheat, and maize) of Punjab, Pakistan. In doing so, simulations are performed using Aspen Plus under various conditions to derive an optimal value of H₂ output. The results indicate significant heterogeneity across districts and crop residues types. Therefore, the Geographic Information System (GIS) is used to draw the spatial distribution of optimal H₂ production across crops and districts. The simulated results reveal that Punjab province has the potential to produce 2619.90 × 10³ Metric tons (MT)/year H_2, and the highest potential derives from sugarcane trash (1012.77 × 10³ MT/year), followed by maize straw (433.67 × 10³ MT/year). The estimated H₂ potential (2.62 million MT/year) can be used in industries, transportation, and urea production as a sustainable alternative in Pakistan.     

Simulating the steam reforming of sunflower meal in Aspen Plus

Hydrogen is a clean energy carrier that has the potential to mitigate the environmentally hazardous effects of fossil fuels. Hydrogen is mainly produced through the steam reforming of natural gas however it is also possible to produce hydrogen through the thermochemical conversion of various biomasses. In this study, three Aspen plus simulation models were developed to obtain hydrogen-rich gas products from biomass through catalytic steam reforming. The results obtained in this modeling study were compared to the experimental data obtained by the steam reforming of the sunflower meal, which is a waste product of the seed oil industry. Out of all three models, model II, in which all of the reactions are assumed to occur simultaneously and all species except for biomass are assumed to undergo combustion reactions, was the most successful one at predicting close results (93% similar) to experimental findings. Using this model, the effect of water:biomass feed ratio on the product yields was tested and the highest possible H₂ yield (44.9 mol H₂/kg sunflower meal) was achieved with a 15:1 water:biomass feed ratio at the constant temperature of 800 °C and atmospheric pressure.     

低温精馏法提纯三氟化硼的工艺研究

针对三氟化硼气体由2.5 N(摩尔分数99.5%)提纯至4 N(摩尔分数99.99%)的技术工艺进行研究,采用双塔连续低温精馏的技术路线;通过Aspen Plus模拟计算,利用灵敏度分析得到最佳的工艺参数,包括操作压力、操作温度、理论板数和回流比等工艺参数,为三氟化硼精制工艺的实验研究奠定了理论基础。     

化工软件在化工课程设计中的应用

化工课程设计是化工及相关专业非常重要的一个教学环节,具有综合性、实践性和工程性。本文介绍了ChemDraw、Aspen Plus和ChemCAD等化工软件在化工课程设计中的应用。结果表明,化工软件增强了学生学习兴趣,提高了课程设计的质量,强化了学生的计算机的应用能力,为学生走向未来的工作岗位打下了扎实的基础。