Fuel Gas Utilization Research Articles

Understanding the oxygen reduction reaction in the hierarchically oriented composite cathode with open, straight pores

The cathode-supported solid oxide fuel cells (SOFCs) have recently attracted great attentions due to the unique advantages of excellent fuel gas utilization and superior thermal reduction stability, but the commercialization process is limited by the poor oxygen reduction reaction (ORR) catalytic performance of low porosities and reduced three phase boundaries (TPBs) cathode substrate. In this case, a novel phase inversion tape casting technology (PITC), have been successfully applied and fabricated an advanced full ceramic bilayer composite cathode support (Sr2Fe1.5Mo0.4Ni0.1O6-δ (SFMNi) – Gd0.2Ce0.8O1.9 (GDC) support/ functional layer) with open, straight pores. The hierarchically oriented pores can be well-kept after high temperature sintering, which significantly enhance the gas (O2) diffusion process in the porous electrode, thus greatly minimizing even eliminating the concentration resistance. Moreover, the introduction of cathode functional layer remarkably enlarges the TPBs density, which is the active sites for ORR, thereby dramatically reducing the electrochemical activation polarization impedance. The full ceramic cathode support exhibits enhanced ORR kinetics activity with a favorable long-term operational stability, indicating that it is an optimized potential cathode support with great application prospects for SOFCs.

Water management and performance enhancement in a proton exchange membrane fuel cell system using optimized gas recirculation devices

Fuel gas utilization and water management are particularly challenging integrated engineering problems in hydrogen-oxygen proton exchange membrane fuel cell (PEMFC) systems. Ejectors are promising fuel cell exhaust gas recirculation devices that can be used to address both challenges. In this study, hydrogen and oxygen recirculation ejectors are designed and manufactured using three-dimensional (3D) printing technology. An experimental investigation on a 1 kW PEMFC system with anodic and cathodic dual-ejector- based gas recirculation is presented. Key parameters such as stack current, stack voltage, cell voltage, operating pressure, and mass flow rate at the primary flow and secondary flow of the anode ejector are measured. The performance of the PEMFC stack equipped with 3D-printed ejectors is compared to that of commercial ejectors. The experimental results reveal that the 3D-printed ejector significantly outperforms the commercial ejector in terms of entrainment ratio, with an improvement rate of up to 31.3%. The performance of the PEMFC stack in the dual-ejector recirculation mode increased by 4.75% with a current density of 320 mA cm−2 compared with dead ended mode in 130 kPa. Furthermore, the dual-ejector recirculation mode of the PEMFC stack outperforms that of the dead-end anode and cathode mode during dynamic loading by alleviating the gas shortage problem of the PEMFC stack.

Performance Evaluation and Degradation Mechanism for Proton Exchange Membrane Fuel Cell with Dual Exhaust Gas Recirculation

Fuel gas utilization and water management are particularly challenging integrated engineering problems in hydrogen–oxygen proton exchange membrane fuel cell (H2/O2 PEMFC) systems. Herein, a standardized process is adopted to evaluate the performance and investigate the degradation mechanisms of a PEMFC with dual exhaust gas recirculation. The purpose of incorporating recirculation subsystems in the fuel cell is to achieve a high fuel gas utilization rate and realize effective water management inside the stack, which consists of 3D‐printed ejectors and a customized recirculation pump. Evaluation of the electrochemical performance degradation and morphological characterization of the fuel cells under different operating strategies are performed after 50 h durability experiments. At a current density of 400 mA cm−2, the performance degradation rates of the stack decrease from 16.50% to 7.49% and 0.71% in the ejector and recirculation pump operation strategies, respectively. The results show that using exhaust gas recirculation devices (ejector/pump) in the fuel cell stack can help in effectively mitigating water flooding and chemical degradation of the membrane electrode assembly. The findings of the study provide a perspective on the exhaust gas recirculation behavior and contribute to the engineering application of H2/O2 PEMFCs.

Development and Research of a Regression Model for Assessing the Efficiency of Gas Compressor Units Operating Modes

This article addresses the issue of improving the energy efficiency of gas transportation equipment in main gas pipelines. To ensure the operation of gas compressor units (GCUs), transported gas is used, and as a result, compressor stations (CSs) consume a significant amount of fuel gas for their own needs. Therefore, increasing the length of main gas pipelines requires a high degree of fuel gas utilization efficiency. The article demonstrates the principles of using GCUs for gas transportation and the operating modes of GCUs. An analysis of methods for assessing the efficiency of GCU operation is conducted. To obtain a forecast of GCU operating modes, a mathematical model for evaluating the efficiency of GCU operating modes is proposed based on real statistical data of equipment operating mode parameters during industrial operation of GCUs in main gas pipelines. The regression model for GCU operating efficiency obtained from calculating the dependency of fuel gas consumption on pressure drop and transported gas flow inadequately reflected the GCU operating mode. To improve accuracy, a regression model for assessing the efficiency of GCU operating modes is developed based on quadratic dependencies on pressure drop, transported gas flow, and gas temperature at the inlet, satisfying the dispatcher control of GCU efficiency.

Development of a 10/40 Kw Rsoc Demonstration System

Scientific ApproachIn the last decade, work on the development of a reversible Solid Oxide Cell (rSOC) technology has been greatly intensified because it can contribute to the storage and the reconversion of electricity from regenerative energy sources.In this context, Forschungszentrum Jülich GmbH first examined the feasibility in a thermodynamic analysis. Here, Frank et al. [1] show that electrical efficiencies of 67% in fuel cell mode and 76% in electrolysis mode can be achieved when such a system is operated with a 70 bar hydrogen storage. This corresponds to a round-trip efficiency of more than 50%.Based on these results, an rSOC system demonstrator with a nominal power of 10 kWel in fuel cell mode and 40 kWel in electrolysis mode was developed. The attached figure shows the simplified system flow diagram.The Integrated Module (IM) is the main component of the rSOC system and consists of four Jülich 20-layer sub stacks in combination with an air and a fuel heat exchanger. Also, five electrically operated heating plates are located within the module to heat up the system from ambient temperature to operating temperature and to support endothermal electrolysis operation. The supporting balance of plant components (BoP) are arranged in the direct vicinity of the IM in order to achieve the most compact layout possible.To be able to classify the efficiency results listed below, the calculation method for the fuel cell efficiency is shown in equation (1), for the electrolysis efficiency in equation (2) and for the power consumption of the BoP in equation (3).\U0001d73c_(\U0001d439\U0001d436, \U0001d446\U0001d466\U0001d460, \U0001d434\U0001d436) = (\U0001d448_\U0001d446\U0001d461\U0001d44e\U0001d450\U0001d458 ∙ \U0001d43c_\U0001d446\U0001d461\U0001d44e\U0001d450\U0001d458 ∙ \U0001d702_\U0001d43c\U0001d45b\U0001d463\U0001d452\U0001d45f\U0001d461\U0001d452\U0001d45f − ∑\U0001d443_(\U0001d435\U0001d45c\U0001d443, \U0001d434\U0001d436))/(\U0001d45b_(\U0001d43b2, \U0001d460\U0001d466\U0001d460\U0001d461\U0001d452\U0001d45a \U0001d456\U0001d45b) ∙ [\U0001d43f\U0001d43b\U0001d449]_\U0001d43b2 ) (1)\U0001d7b0_(\U0001d438\U0001d43f, \U0001d446\U0001d466\U0001d460, \U0001d434\U0001d436) = (\U0001d45b_(\U0001d43b2, \U0001d45d\U0001d45f\U0001d45c\U0001d451\U0001d462\U0001d450\U0001d452\U0001d451) ∙ [\U0001d43f\U0001d43b\U0001d449]_\U0001d43b2)/((\U0001d448_\U0001d446\U0001d461\U0001d44e\U0001d450\U0001d458 ∙ \U0001d43c_\U0001d446\U0001d461\U0001d44e\U0001d450\U0001d458)/\U0001d7b0_\U0001d445\U0001d452\U0001d450\U0001d461\U0001d456\U0001d453\U0001d456\U0001d452\U0001d45f + ∑\U0001d443_(\U0001d435\U0001d45c\U0001d443, \U0001d434\U0001d436)) (2)∑\U0001d443_(\U0001d435\U0001d45c\U0001d443, \U0001d434\U0001d436) = \U0001d443_(\U0001d44e\U0001d456\U0001d45f \U0001d450\U0001d45c\U0001d45a\U0001d45d.) + \U0001d443_(\U0001d451\U0001d456\U0001d44e\U0001d45dℎ\U0001d45f. \U0001d450\U0001d45c\U0001d45a\U0001d45d.) + \U0001d443_(ℎ\U0001d452\U0001d44e\U0001d461\U0001d456\U0001d45b\U0001d454 \U0001d45d\U0001d459\U0001d44e\U0001d461\U0001d452\U0001d460) + \U0001d443_(\U0001d450\U0001d45c\U0001d45b\U0001d461\U0001d45f\U0001d45c\U0001d459 \U0001d460\U0001d466\U0001d460.) + \U0001d443_(\U0001d460\U0001d461\U0001d452\U0001d44e\U0001d45a \U0001d454\U0001d452\U0001d45b\U0001d452\U0001d45f\U0001d44e\U0001d461\U0001d45c\U0001d45f) (3)System operation was started on 06/01/2021. After a short commissioning phase, stationary power points were approached for both operating modes, fuel cell and electrolysis. In fuel cell mode, a power range from 1.7 kWel to 13 kWel could be shown. At the operating point of 500 mA cm-2 with a system fuel gas utilization of 98%, a system output of 10.3 kWel with a maximum efficiency of 63.3% could be achieved. In the case of electrolysis, a system output of - 49.6 kWel with a system efficiency of 71.1% was measured with a steam utilization of 80%.OutlookIn the future it is planned to implement new methods of the stack temperature control based on artificial neural networks. After a successful implementation, realistic load profiles are developed and examined during the system operation.As further development work in the area of SOC system technology, it is planned to investigate combinations with storage on the electrical and gas side, heat recuperation for district heating application as well as further demonstration projects in the area of co-electrolysis with corresponding upstream integration of different CO2 sources and downstream integration of synthesis technologies for the generation of chemicals and e-fuels.AcknowledgementThe authors would like to thank their colleagues at Forschungszentrum Jülich GmbH for their great support and the Helmholtz Society, the German Federal Ministry of Education and Research as well as the Ministry of Culture and Science of the Federal State of North Rhine-Westphalia for financing these activities as part of the Living Lab Energy Campus.References Frank M, Deja R, Peters R, Blum L, Stolten D. Bypassing renewable variability with a reversible solid oxide cell plant. Applied Energy. 2018; 217:101-12. Figure 1

Evaluation of Fundamental Characteristics of High Functional Direct Carbon Fuel Cell Using Wood Pellet as Fuel

After the Great East Japan Earthquake, because the power supply of Japan shifted from nuclear power generation to thermal power generation, the exhaust amount of CO2 as the greenhouse gas increased drastically. On the other hand, Japan has a lot of organic wastes such as a food waste and unused biomass. To solve these problems, we have been developing High Functional Direct Carbon Fuel Cell (HF-DCFC) composed of molten salts gasification system and tubular molten carbonate fuel cell (T-MCFC) since 2012. Molten salts gasification is a technology to produce H2 and CO for T-MCFC from organic wastes. Our previous study obtained the fundamental characteristics of HF-DCFC using soy sauce cake as fuel. Generally, because the operating condition of HD-DCFC depends on a fuel type, we examine the fuel diversity of HF-DCFC. Therefore, this paper aimed to evaluate the fundamental characteristics of HF-DCFC using wood pellet made of unused timber. Moreover, because the performance of T-MCFC depends on the electrolyte loading ratio of both electrodes, this paper also examined the optimum electrolyte loading ratio. In the results of the optimum electrolyte loading ratio, although the performances of the cell to which electrolyte of 45% or more was impregnated were very low under 650℃ of the cell temperature, it has been improved when the cell temperature was raised to 750℃ which was the operating temperature of HF-DCFC. Especially, the diffusion overpotential of each cell was improved greatly by the cell temperature rise. Generally, about three days are required so that the electrolyte is normally distributed to each cell component of a plate type MCFC. Although the distribution of T-MCFC was worse than that of a plate type MCFC because of the difference of the pore structure, it was improved by the decrease in the viscosity of electrolyte by the cell temperature rise. Consequently, we confirmed that the optimum electrolyte loading ratio was in about 25%. On the HF-DCFC experiment, the fundamental characteristic of HF-DCFC was evaluated by the cell voltage change when the wood pellet of 3g was supplied to HF-DCFC generating electricity by a constant current density of 100mA/cm2. The fuel gas utilization was changed from 40% to 80% to evaluate the influence of the gasification gas from the wood pellet on the cell performance. Although the cell power decreases rapidly immediately after the supplying of the wood pellet, thereafter it increases significantly. This tendency becomes large with the increase of the fuel gas utilization. The power descent immediately after the supplying of wood pellet originates to the influence of the air that mixed at the pellet supplying. The cell power descent immediately after the supplying of the pellet originates to the decrease of the partial pressure of hydrogen because of the combustion of air that mixes at the pellet supplying and the T-MCFC fuel gas. Thereafter, the cell power increases rapidly by the increase of fuel gas produced by gasification of the wood pellet. The ratio of the gasification gas in the anode gas increases so that the supply flow rate decreases as the fuel gas utilization increases. Therefore, this tendency increases with the increase of the fuel gas utilization. Consequently, we were able to confirm that HF-DCFC is effective enough as the distributed power source and the waste disposal equipment if wood pellet was supplied to HF-DCFC continuously. Figure 1

Evaluation of Fundamental Characteristics of High Functional Direct Carbon Fuel Cell Using Wood Pellet as Fuel

We have been developing High Functional Direct Carbon Fuel Cell (HF-DCFC) composed of molten salts gasification system and tubular molten carbonate fuel cell (T-MCFC) since 2012. Molten salts gasification is a technology to produce H2 and CO for T-MCFC from organic wastes. This paper aims to evaluate the fundamental characteristics of HF-DCFC using wood pellet made of unused thinning wood and the optimum electrolyte loading ratio. As a result, we were able to confirm that the cell performance of T-MCFC depended on electrolyte loading ratio, and the time for the re-distribution of the electrolyte in the cell component is longer than that of plate type MCFC. We were able to confirm that HF-DCFC is effective enough as the distributed power source and the waste disposal equipment if wood pellet was supplied to HF-DCFC continuously, because the electric power of HF-DCFC was enhanced even if fuel gas utilization increased.

Redefining Water Treatment: Identification of WWTPs as an Earth System Problem and Circular Economic Eco-Bog System to Challenge It

Wastewater Treatment Plants (WWTPs) on the planet, daily processing billions of tons of wastewater and producing masses of sludge accordingly, act like artificial biogeochemical cycles themselves by producing material flow and creating microbial life cycles that normally do not exist in nature, a case with unknown cumulative long-term effects on the planet and human organisms. This study identifies WWTPs as a general Earth system problem with sub-problems to be challenged by new engineering techniques with an integrated natural science perspective. In order to challenge these problems, first the overall ecological role of WWTPs is clarified. Second a literature review (a) on the contents of the end products of wastewater engineering (b) on the effects of utilization of sewage sludge as fertilizer (c) on the utilization of sewage sludge as cement and construction material is provided. Current legal and practical situation in Turkey and EU is very briefly compared. Then, the design of the circular economic eco-bog system, which is a conceptual model of a new technology both to challenge these problems as much as possible and to act as an integrated industrial production system, is introduced. The new system is based on an innovative algaculture and ecomimicry of the evolution of wetland ecosystems from lake to terrestrial ecosystems. Algaculture and artificial bog components of the system use desulphurised fuel gases from both biogas component of the system and also concrete production component of the system. Desulphurization is to avoid H2S production in eco-bog unlike the natural bog ecosystems, and produce sulphurous fertilizers, and produce bog ecosystem services. Since, the fuel gas utilization from the biogas produced by archaebacteria is already net carbon zero, all system makes negative emission, namely sequestration. The CO2 to be released is fixed as biocarbon in algae in agriculture component, and then as organic and inorganic carbon after the sedimentation during accelerated evolution of eco-bog by creating hypoxia, acidification, and eutrophication conditions in artificial lake ecosystem. This sedimentation is mixed with sewage sludge ash for production of cement to have a higher quality concrete. Microbial biofertilizer and organic fertilizers are also produced from the algaculture component of the system, and industrial lichen from bog ecosystem. The system is inspired from lake death mechanisms of the nature, rather than lake health mechanisms in order to capture carbon and nitrogen in lithosphere and biosphere rather than releasing them to atmosphere as fuel gases, imitating natural bogs which are important carbon reservoirs. Finally, a new theorization of the issue is postulated as a way forward to reach SDGs, circular economy and bioeconomy targets of EU Green Deal as well as targets of RIO Conventions and Paris Agreement, not based on water quality arguments but based on mass and energy arguments, as well as arguments for ecologic health and preventive medical treatment for public health, and arguments for integrated industrial production in a holistic manner.

Enhanced by-product fuel gas utilization based on steam parameters improvement

In large smelting plants such as steel plant and coking plant the utilization rate of the byproduct gas is generally low, especially in developing countries. Usually, multiple low-parameter boilers are combined with multiple low-parameter steam turbines, which are built in phases, to drive the smelting accessory machineries. In terms of energy utilization efficiency, this model is definitely not economical. Based on the law of thermodynamics, the direction of efficiency improvement was proposed, and the solution of gas utilization system was put forward, according to the Rankine cycle principle. Finally, with a steel plant as the research object, the proposed scheme was applied in the transformation of this plant, and the economic benefit was estimated. The results show that the proposed scheme in this paper can generate more electricity with the same gas consumption.

Deuterium isotope separation by polymer electrolyte fuel cells connected in series

The separation of hydrogen isotopes has important applications for fundamental science and nuclear engineering. This study investigates isotope separation by stacked polymer electrolyte fuel cells that form part of a combined electrolysis and fuel cell (CEFC) system. Fuel gas containing deuterium (D) was generated by water electrolysis and passed through three fuel cells (FCs) connected in series. Increasing the number of operating FCs in the series greatly improved D separation, but had only a modest impact on power consumption. When all three FCs were individually controlled, the separation efficiency depended on the power condition in each FC. At high current the separation factor of the CEFC system reached over 100 owing to the relationship between fuel gas utilization and separation efficiency.

Catalytic activities of nickel, dolomite, and olivine for tar removal and H2-enriched gas production in biomass gasification process

Tar content in gasification products is a serious problem for fuel gas utilization in downstream applications. Catalytic steam reforming of tar to syngas is a promising way for the removal of tar from the gas products. Nickel-based catalysts, dolomite, and olivine have been widely investigated for tar cracking and reforming by various researchers. This paper presents a review of biomass gasification, tar composition, and its elimination process by using the above three catalysts. This paper summarizes the knowledge in the published literature associated with tar elimination during the biomass gasification including discussion on the effects of different support, promoter on the catalytic performance. The aim of this paper is to collect information on the performance of above catalysts to make them accessible to readers within one paper. Comparative studies on these catalysts carried out by some researchers have also been presented here which show that the nickel-based catalyst is much more active than dolomite and olivine, but they are more expensive and can be also deactivated. Compared to olivine, the dolomite shows better catalytic performance with much higher gas yield and H2. Calcination of these catalysts improves the catalytic activities but the amount of coke deposited on the surface of the dolomite is reported higher than that of the olivine, which may be resulted from the different Fe amount of the catalyst.

A 2D Stationary FEM Model for Hydrocarbon Fuelled SOFC Stack Layers

In previous studies a model framework has been presented, where the physically coupled processes (i) charge-transfer chemistry, (ii) electron and ion conduction and (iii) gas species transport in the porous electrodes for hydrogen (H2) operation are implemented. The model framework has been parametrized with a dataset obtained by electrochemical impedance spectroscopy (EIS), 4-point DC conductivity measurements and evaluation of 3D reconstruction data extracted via FIB-tomography of an anode-supported cell fabricated at Forschungszentrum Jülich (FZJ) [1,2]. In this study, the established model framework is extended to predict local gas composition and electrochemical performance of hydrocarbon fuelled SOFC stacks. The model geometry represents a 2D longitudinal section through a stack layer along the gas channel length. Consequently, the existing isothermal model framework is extended to meet the new requirements: (i) the pressure driven gas transport in the gas channels is modeled by the Navier-Stokes equations and in the porous electrodes by Darcy’s law, (ii) all existing and new gas transport equations are extended to six gas species and (iii) global reaction equations for steam reforming and the water-gas shift reaction are added, as proposed by Ref. [3]. In a previous publication [4] it was shown, that only H2 is electrochemically converted in the Ni/8YSZ anode structure. Hence, the electrochemical charge transfer is modeled by Butler-Volmer approach parameterized for H2 conversion from the existing model framework. Carbon monoxide (CO) as electrochemical active species also present in hydrocarbon fuels is subsequently converted via the water-gas shift reaction at the catalytic active Ni-surface within the porous anode material. The reaction kinetics for these individual reforming reactions have been determined experimentally [5], thus giving the model the capability to predict C/V characteristics dependent on local gas conversion kinetics. This will be shown by a detailed validation where gas concentration profiles recorded via gas chromatography along the gas channel length at open circuit voltage (OCV) are compared with simulated profiles for corresponding gas mixtures (see figure 1). Simulated C/V characteristics are compared with measured data recorded for reformate fuel in a temperature range of T = 680 - 880 °C and a fuel gas utilization between 0 - 69 % (see figure 2). A high level of agreement between simulated and measured data exists throughout the investigated parameter range. The model predicts (i) where gas diffusion limitations lead to drastic performance loss and (ii) where the Ni/8YSZ anode structure most likely will suffer severe damage.

Model Predictions for New Iron Ore Sintering Process Technology Based on Biomass and Gaseous Fuels

In this paper a new technology for a compact iron ore sintering machine is analyzed. The compact sintering process is based on the massive injection of gaseous fuels and the solid fuel is only agglomerated fine charcoal obtained by biomass. The solid fuel used in this study is obtained by agglomeration of fine charcoal produced from elephant glass which has very short period for production and CO2 capture (less than 6 months in tropical climate). To overcome the lower heat supply into the combustion front of the sintering process the simultaneous injection of oxygen and gaseous fuel is proposed. The proposed methodology is to combine the solid fuel (agglomerated fines charcoal) and steelworks gases in a compact machine to enhance heat and mass transfer with high productivity (about 5 times the conventional large machine). A multiphase mathematical model based on transport equations of momentum, energy and chemical species coupled with chemical reaction rates and phase transformations is used to analyze the inner process parameters. A base case representing a possible actual industrial operation of the sintering machine is used in order to compare different scenarios of practicable operations which represents advanced operations techniques. The model was used to predict six cases of combined operation with biomass and fuel gas utilization: a) Scenario 01 and 02: Wind boxes inflow from N01-N10 of rich mixture of natural gas (NG) +Air +O2, b) Scenario 03 and 04: Wind boxes inflow from N01-N10 of rich mixture of coke oven gas (COG)+Air + O2, c) Scenario 05 and 06: Wind boxes inflow from N01-N10 of mixture of COG+BFG+Air+O2. The model predictions indicated that for all cases, the sintering zone is enlarged and the solid fuel consumption is decreased. In order to maximize the steelworks gas utilization it is recommended the use of mixture of COG and BFG with optimum inner temperature distribution within a compact sintering machine (in this study was the scenario 05), which enhance the productivity keeping good inner temperature distribution which promotes formation of calcium ferrites of structural shape which confers adequate metallurgical properties for blast furnace sinter. This technology is also expected to decrease considerably the specific CO2 emissions, as demonstrated by scenarios simulated. It worthy to mention that, although the solid fuel considered in this work is produced from biomass the gas utilization is attractive due to decrease of the CO2 emissions and the gas mixtures can easily be obtained by using inner steelworks gas.

Modeling a Compact Sintering Process Based on Biomass Fuels

This paper is focused on the numerical simulation of a new technology of small size iron ore sintering machine using gaseous fuel and oxygen injections to produce high quality of sinter product for the blast furnace operation. The proposed methodology is to partially replace the solid fuel (coke breeze) by steelworks gases in a compact machine to enhance heat and mass transfer. A multiphase mathematical model based on transport equations of momentum, energy and chemical species coupled with chemical reaction rates and phase transformations is proposed to analyze the inner process parameters. A base case representing a possible actual industrial operation of the sintering machine is used in order to compare different scenarios of possible operations which represents advanced operations techniques. The model was used to predict four cases of fuel gas utilization: a) 3% of the wind boxes inflow from N01-N10 wind boxes of natural gas (NG) and oxygen, b) same condition with coke oven gas (COG) and c) mixture of 80% COG and 20% blast furnace gas (BFG). The model predictions indicated that for all cases, the sintering zone is enlarged and the solid fuel consumption is decreased about 12kg/t of sinter product for the best combination. In order to maximize the steelworks gas utilization it is recommended the use of mixture of COG and BFG with optimum inner temperature distribution within a compact sintering machine, which enhance the productivity and obviously, decrease the investment cost of the sintering facilities.

Model predictions of PCDD and PCDF emissions on the iron ore sintering process based on alternative gaseous fuels

The technology of fuel gas utilization on the iron ore sintering process has been proposed as an alternative for reducing the environmental load and improvements on the sinter quality have been obtained with additional decrease on the return of fines (<5mm). This paper deals with the numerical simulation of this innovative technology in order to evaluate the emissions of poly chlorinated di-benzene dioxin (PCDD) and Poly Chlorinated di-benzene furan (PCDF). The methodology is to partially replace solid fuel (coke breeze) by steelworks gaseous fuels; coke oven gas (COG), blast furnace gas (BFG) and mixture of these gases. A multiphase mathematical model based on transport equations of momentum, energy and chemical species coupled with chemical reaction rates and phase transformations is proposed to analyze the inner process parameters and the rates of PCDD and PCDF formations. A base case representing the actual industrial operation was used to validate the model and afterwards used as reference to predict four cases of fuel gas utilization: (a) 10% of the wind boxes inflow from N01 to N12 wind boxes with COG, (b) same condition with BFG, (c) same condition with 50% COG and 50% BFG and (d) mixture of 25% COG and 75% BFG. The model predictions indicated that for all cases, except only BFG, the sintering zone is enlarged and the solid fuel consumption is decreased. In order to maximize the steelworks gas utilization it is recommended the use of mixture of COG and BFG with optimum inner temperature distribution. It was found out that for all cases of gas utilization the PCDD and PCDF emissions could be decreased due to enlargement of the high temperature zone on the sintering bed and hence increasing the residence time of the reacting gas within the high temperature zone.

Development of an eight-channel NMR system using RF detection coils for measuring spatial distributions of current density and water content in the PEM of a PEFC

The water generation and water transport occurring in a polymer electrolyte fuel cell (PEFC) can be estimated from the current density generated in the PEFC, and the water content in the polymer electrolyte membrane (PEM). In order to measure the spatial distributions and time-dependent changes of current density generated in a PEFC and the water content in a PEM, we have developed an eight-channel nuclear magnetic resonance (NMR) system. To detect a NMR signal from water in a PEM at eight positions, eight small planar RF detection coils of 0.6mm inside diameter were inserted between the PEM and the gas diffusion layer (GDL) in a PEFC. The local current density generated at the position of the RF detection coil in a PEFC can be calculated from the frequency shift of the obtained NMR signal due to an additional magnetic field induced by the local current density. In addition, the water content in a PEM at the position of the RF detection coil can be calculated by the amplitude of the obtained NMR signal. The time-dependent changes in the spatial distributions were measured at 4s intervals when the PEFC was operated with supply gas under conditions of fuel gas utilization of 0.67 and relative humidity of the fuel gas of 70%RH. The experimental result showed that the spatial distributions of the local current density and the water content in the PEM within the PEFC both fluctuated with time.

Hot Utilization of Fuel Gas in Fluidized Bed Biomass Gasification

The characteristics of hot gas utilization are analyzed in the thesis and experiments on rice husk were done in 6 MW bubbling fluidized-bed positive pressure gasification system. The results showed that the positive rice husk gasification system can work well and no tar condensed on the pipes. As sensible heat of hot gas accounting for 11.7% of fuel, the method of hot utilization of fuel gas can make full use of gas energy.

Iron Ore Sintering Process Based on Alternative Gaseous Fuels from Steelworks

This paper deals with the numerical simulation of the new technology of gaseous fuel utilization on the sintering process of iron ore. The proposed methodology is to partially replace the solid fuel(coke breeze) by steelworks gases. A multiphase mathematical model based on transport equations of momentum, energy and chemical species coupled with chemical reaction rates and phase transformations is proposed to analyze the inner process parameters. A base case representing the actual industrial operation of a large sintering machine is used with thermocouples inserted into the sintering bed to record the inner bed temperatures and compare with model predictions in order to obtain model validation and parameters adjustment. Good agreement of the temperature pattern was obtained for the base case and thus, the model was used to predict four cases of fuel gas utilization: a) 2% of the wind boxes inflow from N01-N15 wind boxes of natural gas(NG), b) same condition with coke oven gas(COG), c) same condition with blast furnace gas(BFG) and d) mixture of 50% COG and 50% BFG. The model predictions indicated that for all cases, except only BFG, the sintering zone is enlarged and the solid fuel consumption is decreased about 8kg/t of sinter product. In order to maximize the steelworks gas utilization it is recommended the use of mixture of COG and BFG with optimum inner temperature distribution

Measurement of Time-Dependent Changes and Spatial Distributions of Current Density in PEFC and Water-Content of PEM Using a Planer-Surface Coil as an NMR Signal Detector (Effect of Relative Humidity and Ratio of Utilization of Fuel Gas on Water Content in PEM)

Measurement of Time-Dependent Changes and Spatial Distributions of Current Density in PEFC and Water-Content of PEM Using a Planer-Surface Coil as an NMR Signal Detector (Effect of Relative Humidity and Ratio of Utilization of Fuel Gas on Water Content in PEM)

Biomass Gasification: Catalytic Removal of Tars over Zeolites and Nickel Supported Zeolites

Tars have been identified as one of the major impurities associated with biomass gasification fuel gas. Tar buildup can cause blockages, plugging, corrosion, and catalyst deactivation, resulting in serious operational and maintenance problems. Therefore, tar removal is essential to ensure economic and effective fuel gas utilization. This study investigates the catalytic activity of zeolites and nickel supported zeolites for tar removal. Zeolites with varying pore sizes and acidity were tested, to evaluate the effect of pore size and acidity on tar removal. ZY had better catalytic activity due to its larger pore size compared with ZSM5. Catalytic activity of zeolites increased with an increase in the acidity. ZY-5.2, which is more acidic, had better naphthalene conversions compared with ZY-80. Impregnation of nickel on zeolites improved the activity significantly due to the steam reforming ability of nickel. Long-term catalytic activity tests were performed, the results of which showed that nickel-supporte...