Simultaneous production of two types of synthesis gas by steam and tri‐reforming of methane using an integrated thermally coupled reactor: mathematical modeling

In this work, tri‐reforming and steam reforming processes have been coupled thermally together in a reactor for production of two types of synthesis gases. A multitubular reactor with 184 two‐concentric‐tubes has been proposed for coupling reactions of tri‐reforming and steam reforming of methane. Tri‐reforming reactions occur in outer tube side of the two‐concentric‐tube reactor and generate the needed energy for inner tube side, where steam reforming process is taking place. The cocurrent mode is investigated, and the simulation results of steam reforming side of the reactor are compared with corresponding predictions for thermally coupled steam reformer and also conventional fixed‐bed steam reformer reactor operated at the same feed conditions. This reactor produces two types of syngas with different H₂/CO ratios. Results revealed that H₂/CO ratio at the output of steam and tri‐reforming sides reached to 1.1 and 9.2, respectively. In this configuration, steam reforming reaction is proceeded by excess generated heat from tri‐reforming reaction instead of huge fired‐furnace in conventional steam reformer. Elimination of a low performance fired‐furnace and replacing it with a high performance reactor causes a reduction in full consumption with production of a new type of synthesis gas. The reactor performance is analyzed on the basis of methane conversion and hydrogen yield in both sides and is investigated numerically for various inlet temperature and molar flow rate of tri‐reforming side. A mathematical heterogeneous model is used to simulate both sides of the reactor. The optimum operating parameters for tri‐reforming side in thermally coupled tri‐reformer and steam reformer reactor are methane feed rate and temperature equal to 9264.4 kmol h^?1 and 1100 K, respectively. By increasing the feed flow rate of tri‐reforming side from 28,120 to 140,600 kmol h^?1, methane conversion and H₂ yield at the output of steam reforming side enhanced about 63.4% and 55.2%, respectively. Also by increasing the inlet temperature of tri‐reforming side from 900 to 1300 K, CH₄ conversion and H₂ yield at the output of steam reforming side enhanced about 82.5% and 71.5%, respectively. The results showed that methane conversion at the output of steam and tri‐reforming sides reached to 26.5% and 94%, respectively with the feed temperature of 1100 K of tri‐reforming side. Copyright © 2013 John Wiley & Sons, Ltd.     

Hydrogen rich fuel gas production by gasification of wet biomass using a CO2 sorbent

Hydrogen rich fuel gas production by gasification of wet biomass accompanied by CO₂ absorption is proposed. The paper addressed this topic, and experiments were conducted to investigate the effects of the moisture content (M), the molar ratio of Ca(OH)₂ to carbon in the biomass ([Ca]/[C]) and the reactor temperature (T) on hydrogen production and CO₂ absorption by CaO. Measurement of the calcium compounds in solid residues was carried out with XRD and SEM. The results show that directly gasifying of wet biomass not only favors hydrogen production but also promotes CO₂ absorption by CaO. For the experiment with wet biomass (M = 0.90), the H₂ yield is increased by 51.5% while the CO₂ content is decreased by 28.4% than that for experiments with dry biomass (M = 0.09). CaO plays the dual role of catalyst and sorbent. It is noteworthy that CaO reveals a stronger effect on the water gas shift reaction than on the steam reforming of methane. The increase of the reactor temperature contributes to produce more H₂, but goes against CO₂ absorption by CaO. XRD spectrum and SEM image of the solid residues further confirmed that high temperature is unfavorable to CO₂ absorption by CaO. For the new method, the optimal operating temperature is in the 923–973 K range.     

In-situ CO2 capture in a pilot-scale fluidized-bed membrane reformer for ultra-pure hydrogen production

A novel pilot fluidized-bed membrane reformer (FBMR) with permselective palladium membranes was operated with a limestone sorbent to remove CO₂in-situ, thereby shifting the thermodynamic equilibrium to enhance pure hydrogen production. The reactor was fed with methane to fluidize a mixture of calcium oxide (CaO)/limestone (CaCO₃) and a Ni-alumina catalyst. Experimental tests investigated the influence of limestone loading, total membrane area and natural gas feed rates. Hydrogen-permeate to feed methane molar ratios in excess of 1.9 were measured. This value could increase further if additional membrane area were installed or by purifying the reformer off-gas given its high hydrogen content, especially during the carbonation stages. A maximum of 0.19 mol of CO₂ were adsorbed per mole of CaO during carbonation. For the conditions studied, the maximum carbon capture efficiency was 87%. The reformer operated for up to 30 min without releasing CO₂ and for up to 240 min with some degree of CO₂ capture. It was demonstrated that CO₂ adsorption can significantly improve the productivity of the reforming process. In-situ CO₂ capture enhanced the production of hydrogen whose purity exceeded 99.99%.     

A combined thermodynamic and experimental study on chemical‐looping ethanol reforming with carbon dioxide capture for hydrogen generation

Chemical‐looping ethanol reforming with carbon dioxide capture is proposed. It combines chemical‐looping reforming and carbon dioxide capture for pure hydrogen generation from ethanol with inherent separation of carbon dioxide. A thermal analysis of the process using NiO oxygen carrier is performed by simulating reactions using the Gibbs energy minimization method. The promising systems are investigated further with respect to temperature, NiO/C₂H₅OH molar ratio, CaO/C₂H₅OH molar ratio and pressure changes as well as possible carbon formation in the reformer. Favorable operation conditions in the presence of CaO are: pressures around 3 atm, reactor temperatures around 850 K, NiO/C₂H₅OH molar ratio = 3 and CaO/C₂H₅OH = 3. The H₂ yield and thermal efficiency with CaO addition are higher than that without CaO addition, showing that the addition of a CO₂ sorbent in the process increases the H₂ production. Copyright © 2012 John Wiley & Sons, Ltd.     

H2S effect on dry reforming of biogas for syngas production

The effect of hydrogen sulfide (H₂S) on dry reforming of biogas for syngas production was studied both experimentally and theoretically. In the experimental work, the H₂S effect on Ni‐based catalyst activity was examined for reaction temperatures ranging from 600°C to 800°C. It was found that the presence of H₂S deactivated the Ni‐based catalysts significantly because of sulfur poisoning. Although bimetallic Pt‐Ni catalyst has better performance compared with monometallic Ni catalyst, deactivation was still found. The time‐on‐stream measured data also indicated that sulfur‐poisoned catalyst can be regenerated at high reaction temperatures. In the theoretical work, a thermodynamic equilibrium model was used to analyze the H₂S removal effect in dry reforming of H₂S‐contained biogas. Calcium oxide (CaO) and calcium carbonate (CaCO₃) were used as the H₂S sorbent. The results indicated that H₂S removal depends on the initial H₂S concentration and reaction temperature for both sorbents. Although CO₂ was also removed by CaO, the results from equilibrium analysis indicated that the dry reforming reaction in the presence of CaO was feasible similar to the sorption enhanced water‐gas shift and steam‐methane reforming reactions. The simulation results also indicated that CaO was a more preferable H₂S sorbent than CaCO₃ because syngas with an H₂/CO ratio closer to 2 can be produced and requires lower heat duty.     

Cost‐competitive methane steam reforming in a membrane reactor for H2 production: Technical and economic evaluation with a window of a H2 selectivity

Techno‐economic viability studies of employing a membrane reactor (MR) equipped with H₂ separation membranes for methane steam reforming (MSR) were carried out for H₂ production in Korea using HYSYS®, a well‐known chemical process simulator, including economic analysis based on itemized cost estimation and sensitivity analysis (SA). With the reaction kinetics for MSR reported by Xu and Froment, the effect of a wide range of H₂ selectivity (10‐10,000) on the performance in an MR was investigated in this study. Because of the equilibrium shift owing to the Le Chatelier's principle, great performance of enhancement of methane conversion ( ) and H₂ yield and reaction temperature reduction was observed in an MR compared with a packed‐bed reactor (PBR). A window of a H₂ selectivity from 100 to 300 is proposed as a new criterion for better MR performance of MSR depending on potential applications from in‐depth analysis of and H₂ yield enhancements, a H₂ purity, and temperature reduction. In addition, economic analysis to evaluate the feasibility of an MR technology for MSR was carried out focusing on a levelized cost of H₂ based on itemized cost estimation of capital and operating costs as well as SA. Techno‐economic assessment showed 36.7% cost reduction in an MR compared with a PBR and revealed that this MR technology can be possibly opted for a cost‐competitive H₂ production process for MSR.     

Thermodynamic analysis of combined unit of biomass gasifier and tar steam reformer for hydrogen production and tar removal

A combined unit of biomass gasifier and tar steam reformer (CGR) was proposed in this study to achieve simultaneous tar removal and increased hydrogen production. Tar steam reforming calculations based on thermodynamic equilibrium were carried out by using Aspen Plus software. Thermodynamic analysis reveals that when selecting appropriate operating conditions, exothermic heat available from the gasifier could sufficiently supply to the heat-demanding units including feed preheaters, steam generator and reformer. The effects of gasification temperature (T_gs), reforming temperature (T_ref) and steam-to-biomass ratio (S:BM) on percentages of tar removal and improvement of H₂ production were investigated. It was reported that the CGR system can completely remove tar and increase H₂ production (1.6 times) under thermally self-sufficient condition. The increase of H₂ production is mainly via the water–gas shift reaction.     

Hydrogen-rich gas generation via the exhaust gas-fuel reformer for the marine LNG engine

Reformed exhaust gas recirculation technology has attracted great attention in internal combustion engines. A platform of an exhaust gas-fuel reformer connected with the marine LNG engine was set up for generating on-board hydrogen. Based on the platform, effects of the methane to oxygen ratio (M/O) and reformed exhaust gas ratio (R_EG) from the reformer and excess air ratio (λ) from the engine on the components, hydrogen yield, thermal efficiency and reforming process of the reformer were experimentally investigated. Results shown that hydrogen-rich gases (reformate) can be generated by reforming the mixture of engine exhaust gas (about 400 °C) and methane supplied via the reformer with Ni/Al₂O₃ catalyst, and the hydrogen concentration of reformate was between 6.2% and 12.6% by volume. The methane supplied rate and λ affected the components and temperature of the reactant in the reformer, while R_EG changed the gas hour space velocity during the exhaust gas-fuel reforming processes, resulting in the difference in the components of the reformate and thermal efficiency. At the present experimental condition, the highest H₂ concentration reformate was generated under the M/O of 2.0, λ of 1.55 and R_EG of 6%.     

Optimization of H2 production with CO2 capture by steam reforming of methane integrated with a chemical-looping combustion system

Methane steam reforming (SR) integrated with a chemical-looping combustion (CLC) system is a new process for producing hydrogen from natural gas, allowing carbon dioxide capture with a low energy penalty. In this study, mass and enthalpy balances of an SR-CLC system were carried out to determine the autothermal operating conditions for optimal H₂ production. The evaluation was conducted using iron-based oxygen carriers. Two configurations were analysed, firstly with the reformer tubes inside the fuel reactor and, secondly, with the reformer tubes inside the air reactor. This paper analyses the effect of two parameters affecting the SR process, namely the conversion of methane in the reformer (XCH₄$X_{{\text{CH}}_4}$) and the efficiency of the hydrogen separation of a pressure swing adsorption (PSA) unit (η_PSA), as well as two parameters affecting the CLC system, namely the Fe₂O₃ content in the oxygen carrier and its conversion variation (ΔX_OC), on the H₂ yields. Moreover, it also analyses the reduction of Fe₂O₃ to Fe₃O₄ or to FeAl₂O₄. The results shown that a H₂ yield value of 2.45 mol H₂ per mol of CH₄ can be obtained with the reformer tubes located inside the air reactor and with Fe₂O₃ being reduced to Fe₃O₄. This corresponds to a CH₄ to H₂ conversion of 74.2%, which is similar to state-of-the-art H₂ production technologies, but with inherent CO₂ capture in the SR-CLC process.     

In-situ studies of gas phase composition and anode surface temperature through a model DIR-SOFC steam–methane reformer at 973.15 K

A comparative study into the effects of total volume flow rate, methane ‘residency time’, methane volume flow rate, and steam-to-carbon ratio on the steam–methane reforming process was performed in a model Direct Internal Reforming SOFC (DIR-SOFC) reformer operating in steady state at a nominal temperature of 973 K. The spatial distributions of major gas species (CH₄, H₂O, CO, CO₂, and H₂) over the reformer surface were measured in-situ using Vibrational Raman Spectroscopy. Surface temperature measurements were recorded using IR thermometry. The effects of varying the intake mole fractions of methane and water were considered. The results of this work have demonstrated a strong positive correlation between the intake mole fraction of methane and the rate of the steam–methane reformation reaction. A weak negative correlation between the intake mole fraction of water and the rate of the reformation reaction was also shown.     

Towards H2-rich gas production from unmixed steam reforming of methane: Thermodynamic modeling

In this work, the Gibbs energy minimization method is applied to investigate the unmixed steam reforming (USR) of methane to generate hydrogen for fuel cell application. The USR process is an advanced reforming technology that relies on the use of separate air and fuel/steam feeds to create a cyclic process. Under air flow (first half of the cycle), a bed of Ni-based material is oxidized, providing the heat necessary for the steam reforming that occurs subsequently during fuel/steam feed stage (second half of the cycle). In the presence of CaO sorbent, high purity hydrogen can be produced in a single reactor. In the first part of this work, it is demonstrated that thermodynamic predictions are consistent with experimental results from USR isothermal tests under fuel/steam feed. From this, it is also verified that the reacted NiO to CH₄ (NiO_reacted/CH₄) molar ratio is a very important parameter that affects the product gas composition and decreases with time. At the end of fuel/steam flow, the reforming reaction is the most important chemical mechanism, with H₂ production reaching ∼75 mol%. On the other hand, at the beginning of fuel/steam feed stage, NiO reduction reactions dominate the equilibrium system, resulting in high CO₂ selectivity, negative steam conversion and low concentrations of H₂. In the second part of this paper, the effect of NiO_reacted/CH₄ molar ratio on the product gas composition and enthalpy change during fuel flow is investigated at different temperatures for inlet H₂O/CH₄ molar ratios in the range of 1.2-4, considering the USR process operated with and without CaO sorbent. During fuel/steam feed stage, the energy demand increases as time passes, because endothermic reforming reaction becomes increasingly important as this stage nears its end. Thus, the duration of the second half of the cycle is limited by the conditions under which auto-thermal operation can be achieved. In absence of CaO, H₂ at concentrations of approximately 73 mol% can be produced under thermo-neutral conditions (H₂O/CH₄ molar ratio of 4, with NiO_reacted/CH₄ molar ratio at the end of fuel flow of ∼0.8, in temperature range of 873-1073 K). In the presence of CaO sorbent, using an inlet H₂O/CH₄ molar ratio of 4 at 873 K, H₂ at concentrations over 98 mol% can be obtained all through fuel/steam feed stage. At 873 K, carbonation reaction provides all the heat necessary for H₂ production when NiO_reacted/CH₄ molar ratio reached at the end of fuel/steam feed is greater or equal to1. In this way, the heat released during air flow due to Ni oxidation can be entirely used to decompose CaCO₃ into CaO. In this case, a calcite-to-nickel molar ratio of 1.4 (maximum possible value) can be used during air flow. For longer durations of fuel/steam feed, corresponding to lower NiO_reacted/CH₄ molar ratios, some heat is necessary for steam reforming, and a calcite-to-nickel molar ratio of about 0.7 is more suitable. With the USR technology, CaO can be regenerated under air feeds, and an economically feasible process can be achieved.     

Performance analysis of a membrane‐based reformer‐combustor reactor for hydrogen generation

Hydrogen is mostly produced in conventional steam methane reforming plants. In this work, we proposed a membrane‐based reformer‐combustor reactor (MRCR) for hydrogen generation in order to improve heat recovery and overall thermal efficiency. The proposed configuration will also reduce the complexity in existing steam methane reforming (SMR) plants. The proposed MRCR comprises combustion zone, hydrogen permeate zone, and SMR zone. A computational fluid dynamics model was developed using ANSYS‐Fluent software to simulate and analyze the performance of the proposed MRCR. Results show that high hydrogen yields were observed at high reformer pressures (RPs) and low gas hourly space velocities (GHSVs). Furthermore, by increasing the steam to methane ratio and addition of excess air in the combustion side, the hydrogen yield from the MRCR decreases. This is attributed to the reduction in the effective temperature of the hydrogen membrane. High RP, low GHSV, and low steam to methane ratio that increased the hydrogen yield also decreased carbon monoxide (CO) emissions. For an increased RP from 1 to 10 bar, the CO emission decreased by about 99%. The reduction in CO emission at high RP would be attributed to the effect of water gas shift reaction in the MRCR. Results of the extensive parametric study presented in this work can be used to determine the operating conditions based on tradeoffs between hydrogen yield (mole H₂/mole CH₄), hydrogen production rate (kg of H₂/h), allowable CO emissions, and exhaust gas temperature for other applications such as gas turbine.     

Experimental study of syngas production from methane dry reforming with heat recovery strategy

This study employed the concept of heat recovery to design a set of reformer to facilitate the methane dry reforming (MDR), through which syngas (H₂+CO) could be generated. The MDR involves an endothermic reaction and thus additional energy is required to sustain it. According to the concept of industrial heat recovery, the energy required to facilitate the MDR was recovered from waste heat. In addition, after the reforming reaction, the waste heat inside the reformer was used for internal heat recovery to preheat the reactants (CO₂+CH₄) to reduce the amount of energy required for the reforming reaction. Regarding the parameter settings in the experiments, the CH₄ feed flow rate was set at 1–2.5 NL/min and the mole ratio for CO₂/CH₄ was set at 0.43–1.22. Subsequently, an oven was used to simulate a heat recovery environment to facilitate the dry reforming experiment. The experimental results indicated that an increase in oven temperature could increase the reforming reaction temperature and elevate the energy for the reformer. H₂ and CO production could increase when the reformer gained more energy. The high-temperature gas generated from the reforming reaction was applied to facilitate internal heat recovery of reformer and preheat the reactants; thus, the efficiency of reforming and CO₂ conversion were evidently elevated. The theoretical equilibrium analysis indicated that the thermal efficiency of reforming increased with the increase of CO₂/CH₄ molar ratio. While, the thermal efficiency of reforming by experiments decreased with the increase of the CH₄ feed rate, but increased with the increase of CO₂/CH₄. In summary, the experimental results revealed that the overall H₂ was 0.017–0.019 mol/min. In addition, the reforming efficiency was 8.76%–78.08%, the CO₂ conversion was 53.92%–96.43%, and the maximum thermal efficiency of reforming was 102.3%.     

Catalytic reforming of natural gas for hydrogen production in a pilot fluidized-bed membrane reactor: Mapping of operating and feed conditions

A fluidized-bed membrane reformer was operated in two independent laboratories to map various operating conditions, to investigate the effects of changing the composition of the natural gas feed stream and to verify earlier experimental trials. Two feed natural gases were tested, containing either 95.5 or 90.1 mol% of methane (3.6 or 9.9 mol% of other gaseous higher hydrocarbons). Experimental tests investigated the influence of total membrane area, reactor pressure, permeate pressure and natural gas feed rates. A permeate-H₂-to reactor natural gas feed molar ratio >2.3 was achieved with six two-sided membrane panels under steam reforming conditions and a pressure differential across the membranes of 785 kPa. The total cumulative reforming time reached 395 h, while hydrogen purity exceeded 99.99% during all tests.     

Simulation of steam reforming of biogas in an industrial reformer for hydrogen production

The paper aims to investigate the steam reforming of biogas in an industrial-scale reformer for hydrogen production. A non-isothermal one dimensional reactor model has been constituted by using mass, momentum and energy balances. The model equations have been solved using MATLAB software. The developed model has been validated with the available modeling studies on industrial steam reforming of methane as well as with the those on lab-scale steam reforming of biogas. It demonstrates excellent agreement with them. Effect of change in biogas compositions on the performance of industrial steam reformer has been investigated in terms of methane conversion, yields of hydrogen and carbon monoxide, product gas compositions, reactor temperature and total pressure. For this, compositions of biogas (CH₄/CO₂ = 40/60 to 80/20), S/C ratio, reformer feed temperature and heat flux have been varied. Preferable feed conditions to the reformer are total molar feed rate of 21 kmol/h, steam to methane ratio of 4.0, temperature of 973 K and pressure of 25 bar. Under these conditions, industrial reformer fed with biogas, provides methane conversion (93.08–85.65%) and hydrogen yield (1.02–2.28), that are close to thermodynamic equilibrium condition.     

Hydrogen production using integrated methanol‐steam reforming reactor with various reformer designs for PEM fuel cells

A 95 mm × 40 mm × 15 mm compact reactor for hydrogen production from methanol‐steam reforming (MSR) is constructed by integrating a vaporizer, reformer, and combustor into a single unit. CuO/ZnO/Al₂O₃ is used as the catalyst for the MSR while the required heat is provided using Platinum (Pt) ‐catalytic methanol combustion. The reactor performance is measured using three reformer designs: patterned micro‐channel; inserted catalyst layer placed in a single plain channel; and catalyst coated directly on the bottom wall of single plain channel. Because of longer reactant residence time and more effective heat transfer, slightly higher methanol conversion can be obtained from the reformer with patterned microchannels. The experimental results show that there is no significant reactor performance difference in methanol conversion, hydrogen (H₂) production rate, and carbon monoxide (CO) composition among these three reformer designs. These results indicated that the flow and heat transfer may not play important roles in compact size reactors. The reformer design with inserted catalyst layer provides convenience in replacing the aged catalyst, which may be attractive in practical applications compared with the conventional packed bed and wall‐coated reformers. Copyright © 2011 John Wiley & Sons, Ltd.     

Thermodynamic analysis of plant-wide CLC-SESMR scheme for H2 production: Studying the effect of oxygen carrier supports

Sorption enhanced steam methane reforming (SESMR) integrated with chemical looping combustion (CLC) is one of the most capable greener technologies that allows co-generation of H₂ from natural gas together with CO₂ capture. The performance of CLC mainly depends on the sustained reactivity, strength and durability of oxygen carriers (OCs). A suitable combination of active OCs with optimal inert composition is essential to meet the overall thermal demand of integrated CLC-SESMR process. In this work, the effect of inert OC supports on the performance of CLC-SESMR has been studied through thermodynamic analysis based on steady-state plant wide models developed using ASPEN plus. Ni-based OCs are considered with two different support materials, SiC/Al₂O₃ and MgAl₂O₄ at different inert compositions ranging from 0 to 70% by weight. The sensitivity analysis results revealed that H₂ purity and CO₂ captured are directly proportional to the inert composition while H₂ yield is inversely proportional. The optimal inert compositions are found to be 30% and 40% by weight for the respective cases of SiC/Al₂O₃ and MgAl₂O₄. In both the cases, the overall performance of CLC-SESMR is found to be nearly same, i.e., with 97% overall methane conversion, 96% CO₂ captured, 98.3% H₂ purity, 2.24 H₂ yield, and 71.4% net plant efficiency.     

Axial heat conduction and heat supply effects on methanol-steam reforming performance in micro-scale reformers

The methanol-steam reforming (MSR) performance in micro-scale tubular reformers made by various materials is numerically studied. The physical domain considered includes an inlet section for methanol-steam mixture supply, a reformer section packed with CuO/ZnO/Al₂O₃ catalyst particles and an outlet section for reformed gas collection. The heat transfer effect with three different heat supply mechanisms on the MSR performance is addressed. For heat supplies from the applied heat fluxes at the reformer outer wall surface and from internal heat generation in the reformer wall, it is found that the axial conduction plays an important role in both heat transfer characteristics and MSR performance. It is suggested that the reformer have a small axial conduction parameter for high MSR performance which can be achieved by designing the reformer with low wall thermal conductivity, thin wall thickness and a small reactants feed rate. It is also found that an excess heat supply can be obtained when the axial conduction parameter is small. This excess heat supply enhances the MSR performance compared with the infinitely-thin walled reformer. For the reformer with a constant wall outer surface temperature, the wall material effect on the MSR performance is insignificant due to uniformly distributed reformer wall temperature.     

Hydrogen synthesis from biomass pyrolysis with in situ carbon dioxide capture using calcium oxide

Hydrogen (H₂) and other gases (CO₂, CO, CH₄, H₂O) produced during the pyrolysis of cellulose, xylan, lignin and pine (Pinus radiata), with and without added calcium oxide (CaO), were studied using thermogravimetry-mass spectrometry (TG-MS) and thermodynamic modeling. CaO improved the H₂ yield from all feedstocks, and had the most significant effect on xylan. The weight loss of and gas evolution from the feedstocks were measured over the temperature range 150-950 °C in order to investigate the principle mechanism(s) of H₂ formation. Without added CaO, little H₂ was produced during primary pyrolysis; rather, most H₂ was generated from tar-cracking, reforming, and char-decomposition reactions at higher temperatures. When CaO was added, significant H₂ was produced during primary pyrolysis, as the water-gas shift reaction was driven toward H₂ formation. CaO also increased the formation of H₂ from reforming and char gasification reactions. Finally, CaO increased the extent of tar cracking and char decomposition, and lowered their onset temperatures. The production of H₂ from pine over the course of pyrolysis could be modeled by summing the H₂ evolutions from the separate biomass components in relevant proportions.     

Interactive heat transfer characteristics of 5 kW class shell-and-tube methane steam reformer with intermediate temperature heat source

A 5 kW class shell and tube methane steam reformer (MSR) with intermediate temperature heat source was evaluated to find a correlation between the methane conversion and heat transfer performance. First, performance evaluation of MSR1 was conducted by varying experimental conditions such as reformer reactant flow rate, steam to carbon ratio (SCR), inlet temperature of reforming zone, and inlet temperature of heat source. Sensitivity study of overall heat transfer coefficient was also carried out to find the major parameter affecting the heat transfer. Next, the heat transfer performance and methane conversion rate of MSR1 and 2 were compared. Both reformers have the same gas hourly space velocity (GHSV) in the form of shell and tube heat exchangers, but are designed to compare the heat transfer characteristics of the reformer by designing with the different heat transfer areas. The results show that the main factors affecting the performance of the reformer are load, heat source inlet temperature, and heat transfer area.