Simulation of hydrogen production for mobile fuel cell applications via autothermal reforming of methane

This paper presents a simulation of catalytic autothermal reforming (ATR) of methane (CH4) for hydrogen (H2) production. ATR is essentially an oxidative steam reforming, which combines the exothermic partial oxidation (PO) with the endothermic steam reforming (SR) under thermally neutral conditions. A model is developed using HYSYS 2004.1 to simulate the conversion behavior of the reformer. The model covers all aspects of major chemical kinetics and heat and mass transfer phenomena in the reformer. The ATR and preferential oxidation (PrOx) processes is modeled using conversion reactor, while the water gas shift (WGS) process is modeled using equilibrium reactor within HYSYS environment. The conditions used for high CH4 conversion and high H2 yield are at air to fuel ratio of 2.5 and water to fuel ratio of 1.5. Under this condition, CH4 conversion of 100% and H2 yield of 44% on wet basis can be achieved and the system efficiency is about 87.7%

Pyrolysis of Empty Fruit Bunch by Thermogravimetric Analysis

AbstractThe purpose of this paper is to study the characteristics of as received and wet-treated empty fruit bunch (EFB) for bio-oil production via pyrolysis technology. The elemental properties of the feedstock were characterized by an elemental analyzer while thermal properties were investigated using thermogravimetric analyzer (TGA). The pyrolysis process was being carried out at room temperature up to 700°C in the presence of nitrogen gas flowing at 150ml/min. The investigated parameters are particle sizes and heating rate. The particle sizes varied in the range of dp1<0.25mm and 0.25≤ dp2<0.30mm. The heating rates used were 50°C/min and 80°C/min. From the results obtain, smaller particle size dp1 produces 10% less char yields, while higher heating rate of 80°C/min increases rate of decomposition by almost 1mg/s. Treatment process reduces char yields of dp2 by a total of 5%. This study can provide an important basis in determining suitable properties of EFB and pyrolysis parameter for bio-fuel production via pyrolysis

Sustainable design improvement for direct-indirect sequence of aromatic separation process

Distillation operations became a major concern within sustainability challenge, which it becomes a primary target of energy saving efforts in industrially developed countries. However, there is still one problem, which is how do we improve the energy efficiency of the existing distillation columns systems by considering the sustainability criteria without having major modifications. Recently, a new energy efficient distillation columns methodology that will able to improve energy efficiency of the existing separation systems without having major modifications has been developed. After all, this developed methodology was only considered the energy savings without taking into consideration the sustainability criteria

Energy efficient distillation columns sequence for hydrocarbon mixtures fractionation process

The objective of this paper is to present the study and analysis of the energy saving improvement for the hydrocarbon mixtures (HM) fractionation process by using driving force method. To perform the study and analysis, the energy efficient HM fractionation plant methodology is developed. Accordingly, the methodology consists of four hierarchical steps; step 1: existing HM sequence energy analysis, step 2: optimal HM sequence determination, step 3: optimal HM sequence energy analysis, and step 4: energy comparison and economic analysis. In the first step, a simple and reliable short-cut method of process simulator (Aspen HYSYS) is used to simulate a base (existing) HM sequence. The energy used to recover individual fractions in the base sequence is analyzed and taken as a reference. In the second stage, an optimal HM sequence is determined by using driving force method. All individual driving force curves for all adjacent components are plotted and the optimal sequence is determined based on the plotted driving force curves. Once the optimal HM sequence has been determined, the new optimal sequence is then simulated in step three using a simple and reliable short-cut method (using Aspen HYSYS), where the energy used in the optimal HM sequence is analyzed. Finally, the energy used in the optimal HMs sequence is compared with the base sequence. The return of investment (ROI) and simple payback period are also calculated. Several case studies have been used to test the performance of the developed methodology. The results show that a maximum energy saving of 40% was achieved when compared the optimal (driving force) sequence with the existing direct sequence. The ROI of 3 was obtained with 4 month of payback period. It can be concluded that, the sequence determined by the driving force method is able to reduce energy used for HM fractionation process. Individual column energy has also been analyzed, and from that several columns that can be improved in terms of energy saving have been identified. All of this findings show that the methodology is able to design minimum energy distillation column sequence for HM fractionation process in an easy, practical and systematic manner

Energy efficient distillation columns analysis for aromatic separation process

Distillation operations became a major concern within energy savings challenge, which it becomes a primary target of energy saving efforts in industrially developed countries. However, there is still one problem, which is how do we improve the energy efficiency of the existing distillation columns systems by without having major modifications. Recently, a new energy efficient distillation columns methodology that will able to improve energy efficiency of the existing separation systems without having major modifications has been developed. Therefore, the objective of this paper is to present new improvement of existing methodology by designing an optimal sequence of energy efficient distillation columns using driving force method. Accordingly, the methodology is divided into four hierarchical sequential stages: i) existing sequence energy analysis, ii) optimal sequence determination, iii) optimal sequence energy analysis, and iv) energy comparison and economic analysis. In the first stage, a simple and reliable short-cut method is used to simulate a base (existing) sequence. The energy consumption of the base sequence is calculated and taken as a reference for the next stage. In the second stage, an optimal sequence is determined by using driving force method. All individual driving force curves is plotted and the optimal sequence is determined based on the plotted driving force curves. Then, by using a short-cut method, the new optimal sequence is simulated and the new energy consumption is calculated in the third stage. Lastly, in the fourth stage, the energy consumption for both sequences (base and optimal) is compared. The capability of this methodology is tested in designing an optimal synthesis of energy efficient distillation columns sequence of aromatics separation unit. The existing aromatics separation unit consists of six compounds (Methylcyclopentane (MCP), Benzene, Methylcyclohexane (MCH), Toluene, m-Xylene and o-Xylene) with five direct sequence distillation columns is simulated using a simple and reliable short-cut method and rigorous within Aspen HYSYS® simulation environment. The energy and economic analysis is performed and shows that the optimal sequence determined by the driving force method has better energy reduction with total of 6.78% energy savings and return of investment of 3.10 with payback period of 4 months. It can be concluded that, the sequence determined by the driving force method is not only capable in reducing energy consumption, but also has better economic cost for aromatic separation unit

Sustainable energy efficient distillation columns sequence design of aromatic separation unit

Distillation operations became a major concern within sustainability challenge, which it becomes a primary target of energy saving efforts in industrially developed countries. However, there is still one problem, which is how do we improve the energy efficiency of the existing distillation columns systems by considering the sustainability criteria without having major modifications. Recently, a new energy efficient distillation columns methodology that will able to improve energy efficiency of the existing separation systems without having major modifications has been developed. However, this developed methodology was only considered the energy savings without taking into consideration the sustainability criteria. Therefore, the objective of this paper is to present new improvement of existing methodology by including a sustainability analysis to design an optimal sequence of energy efficient distillation columns. Accordingly, the methodology is divided into four hierarchical sequential stages: i) existing sequence sustainability analysis, ii) optimal sequence determination, iii) optimal sequence sustainability analysis, and iv) sustainability comparison. In the first stage, a simple and reliable short-cut method is used to simulate a base (existing) sequence. The sustainability index of the base sequence is calculated and taken as a reference for the next stage. In the second stage, an optimal sequence is determined by using driving force method. All individual driving force curves is plotted and the optimal sequence is determined based on the plotted driving force curves. Then, by using a short-cut method, the new optimal sequence is simulated and the new sustainability index is calculated in the third stage. Lastly, in the fourth stage, the sustainability index for both sequences (base and optimal) is compared. The capability of this methodology is tested in designing an optimal sustainable energy efficient distillation columns sequence of aromatics separation unit. The existing aromatics separation unit consists of six compounds (Methylcyclopentane (MCP), Benzene, Methylcyclohexane (MCH), Toluene, m-Xylene and o-Xylene) with five direct sequence distillation columns is simulated using a simple and reliable short-cut method and rigorous within Aspen HYSYS simulation environment. The energy and sustainability analysis is performed and shows that the optimal sequence determined by the driving force method has better energy reduction with total of 6.78 % energy savings and 0.16 % sustainability reduction compared to existing sequence with. In addition, the economic analysis shows that the return of investment of 3.10 with payback period of 4 months. It can be concluded that, the sequence determined by the driving force method is not only capable in reducing energy consumption, but also has better sustainability index for aromatic separation unit

Dynamic modelling of fuel cell system for mobile application using Simulink environment

Nowadays, the increment of the petrol price has been a major problem for the consumers and it will increase more than 4 cent per litter in period of 6 to 12 month. Thus, there are many new energy developments that friendly to the environment have been commercialized to overcome this phenomenon such as solar energy and fuel cells technology. Among these, fuel cell power systems for transportation applications have received increased attention in recent years because of the potential for high fuel efficiency and lower emissions. A fuel cell converts hydrogen and oxygen into water, directly generating electrical energy from chemical energy without being restricted by efficiency limits of the Carnot thermal cycle (Larminie et al., 2000)

Kinetic analysis of Malaysia type biomasses via thermogravimetric analyser (TGA)

The kinetic behaviour of biomass pyrolysis samples was successfully studied via thermogravimetric analysis. The biomass samples were empty fruit bunch, oil palm trunk, rice husk, coconut copra, sawdust, coconut shell, sugarcane bagasse, and wood bark. The analysis was performed in a nitrogen atmosphere from 30 to 700°C. The effect of heating rate on kinetic behaviour of biomass at two different high heating rates was evaluated at 40°C/min (HR1) and 80°C/min (HR2). The kinetic parameters of biomass samples such as pre-exponential factor (s-1), activation energy (kJ/mol), and reaction order (n) were determined using one-step global kinetic model. The wood bark sample has the lowest activation energy (38.14 kJ/mol), while coconut copra was reported for the highest activation energy (145.42 kJ/mol). High positive activation energy was achieved at a higher heating rate (HR2) than at lower heating rate (HR1) for biomass samples

Design of bench-scale fast pyrolysis reactor for bio-fuel production

Fast pyrolysis technology had been studied extensively with a purpose to utilize biomass for fuel and energy application. The main product from this process, bio-oil can be further processed into transportation fuel, power generation and chemicals. The most challenging aspect is to develop an economic viable platform for processing capital. Biomass contains low energy content of ~150kg/m3, which corresponds to high transportation cost from source to processing plant. Conversion of biomass into liquid fuels can increase the energy content by 10 times higher and reduce transport cost up to 87 %