Volume 11, Issue 2 -

This paper reviews research trends in modeling for low-carbon energy production. The focus is on two currently significant low-carbon energy processes; namely, bioenergy and post-combustion carbon capture (PCC) processes. The fundamentals of these two processes are discussed and the role of modeling and simulation tools (MSTs) is highlighted. The most popular modeling software packages are identified and their use in the literature is analyzed. Among commercially available packages, it is found that no single software package can handle all process development needs such as, configuration studies, techno-economic analysis, exergy optimization, and process integration. This review also suggests that optimal modeling results reported in literature can be viewed as optimal at the individual plant level, but sub-optimal for plant superstructure level. This review has identified key gaps pertinent to developing hybrid models that describe integrated energy production processes. ASPEN Plus is found to be dominant for modeling both bioenergy and PCC processes for both steady-state and dynamic modes respectively.

The present study aims to explore the possibility of promoting hydrogen and syngas production capacity and quality by steam (SRP) and oxidative steam (OSRP) reforming of propane with and without H 2 and CO 2 removal. Conditions studied are temperature range of 600–1,100 K under atmospheric pressure with steam to propane feed ratio (WPR) of 1–18, oxygen to propane feed ratio (OPR) and fractional removal of H 2 and CO 2 (f) ranging from 0–0.99. The results indicate that SRP with 99% H 2 removal produces high H 2 yield of 9.93 moles close to theoretical value of 10 moles at relatively low temperature (750 K) than SRP (950 K). Approximately identical results are achieved at 950 K with 99% CO 2 removal at same conditions of WPR (12), pressure (1 atm), and complete conversion of propane. Thus, SRP with H 2 removal is more energy saving process. In OSRP, lower OPR, higher WPR minimize CO and CH 4 production but at the expense of H 2 production. However, OSPR process is the most suitable process to provide most favourable H 2 /CO ratio in syngas. Molar H 2 /CO ratio in syngas in the range of 1–3 are found at T ≥1,000 K, WPR≤6 in SRP, SRP with H 2 removal ( f =0.4–0.99) and OSRP (OPR=0.2–2). Thermal efficiency is higher than 80% in both SRP with H 2 or CO 2 removal than SRP(69.39%). The thermal efficiency in OSRP is less than 69%. Hence, propane reforming process in hydrogen selective membrane reactor, provides high quality of hydrogen at relatively lower energy utilization.

The kinetic model parameters are estimated for lactic acid production using mixed microbial consortium in batch fermentation by using different optimization methods. For every time interval concentrations are measured and formulated the parameter appraisal delinquent. Cellular progression kinetic model of exponential or logistic was verified for the effect of various substrates and lactic acid production of mixed culture. This paper proposed hybrid algorithm such as nonlinear models in conjunction with differential evolution and kinetic model. The nonlinear regression with graphical method and Nelder-Mead simplex linked kinetic model was compared with the differential evolution for parameter estimation. The optimized kinetic parameters are found to be within the range of experimental conditions for which the model is developed offers a significant enhancement of lactic acid production. From the computational results, the proposed kinetic model linked differential evolution strategy is thus found effective in exploring the input search space and optimizing the kinetic parameters.

In this study a novel approach is presented to optimize the layout of petrochemical units, considering the most likely scenario. To illustrate the method a real case study, exporting petrochemical tank farm (Esfahan petrochemical, Iran), was selected. Three objective functions like, piping cost, occupied land cost and human losses were combined and the total cost function was minimized. The required data for lethality function were obtained using simulation of different scenario by Phast software. A sigmoid function was fitted to the data which can estimate the lethality based on the distance from incident point. Genetic algorithm (GA) was used to minimize the total cost function. Due to vastness of searching area, more than one optimum layout was obtained. Finally, the optimum layouts were simulated with fire ball scenario and a good agreement was obtained between optimum points and simulated data.

The pneumatic conveying experiment bed has been established to study the flow characteristics of air- solids two-phase flow in horizontal pipeline. Euler model was applied to simulate it based on analysis of Gambit and fluid analysis software-fluent. The simulated results indicated: under the same gas phase conveying flow and pressure, the bigger particle diameter is, the bigger pressure drop is in the horizontal pipeline. The smaller particle diameter is, the more uniform of the particle’s distribution is, and the more easily obtaining the acceleration is. Particle concentration at the bottom of the horizontal pipe is increasing in the axial direction, while close to the tail pipe it will be reduce. The simulated conclusion is consistent with the actual measurement results, herewith rendering some footing for engineering design and theoretical research on pneumatic conveying systems.

In this research, landfill solid waste was solidified as cement-waste matrix to protect the environment from excessive intrusive contaminants like Fe, Cu and Ni and minimize the waste load. Within this context, ingredients of cement-waste mortar were characterized to determine their physical properties. Long-term feasibility study was conducted to examine the metal contents stabilization by employing the standard mass transfer-leaching test. The cumulative leaching concentration of Fe, Cu and Ni were found to be 1.29 mg/l, 0.18 mg/l and 0.63 mg/l respectively up to 180 days static leaching test period that satisfied the surface water quality standard. Mechanical strength test was also conducted to characterize the solidification technique. Five well-established non-linear mathematical Models were conducted to evaluate the mechanisms of Fe, Cu and Ni migration. Goodness of fit statistical parameter analysis and visual examination indicated that polynomial equation Model is better for explaining the experimentally generated data. Moreover, parameter of polynomial equation was extended from five to nine for examining the best calibration profile to the observations. In context of slope-intercept and visual observation analysis resulted that polynomial equation based Model bearing five parameters with 0.5 power interval of each parameter describes the leaching phenomena quite similar with the experimental observations whereas goodness of fit parameters and information criterion shows reverse. It was found that the studied immobilized landfill waste mortar have acceptable mechanical performance that confirms to be used as construction material.