10千瓦级分布式天然气-质子交换膜燃料电池示范电站(英文)

A 10 kW-scale natural gas fueled proton exchange membrane fuel cell (PEMFC) distributed power plant is presented in this paper, which is designed for cogeneration of power and heat. With homemade catalysts for CO removal in a two-stage methanation process and integrated reactor in the fuel processing system, the reformed fuel with CO molar fraction less than 105 is obtained for the fuel cell stack. Based on Matlab/Simulink/Stateflow and xPC Target platform, a rapid control prototype (RCP) is developed for real-time condition management, signal tracking and parameter tuning, data storing, and man-machine interaction. In a typical running with 4.3 kW stack power, the hydrogen production efficiency, gross power generation efficiency and heat recovery efficiency approach to 76%, 41% and 50%, respectively. The peak stack power reaches 7.3 kW. Though there is still considerable distance to long-term operation at 10 kW-scale net power generation, it is a milestone for the PEMFC-based stationary application in China.     

SIMULATION ANALYSIS AND OPTIMIZATION OF STEAM REFORMING PROCESS FOR A LARGE-SCALE AMMONIA PLANT

The present paper shows how the Schuster Schwarzschild method developed originally inastrophysics can be adopted to simulate the performance of the primary reforming furnace in an am-monia plant.This method facilitates the simulation of heat transfer and reaction in the furnace andimproves the computational efficiency.Simulation analysis is carried out to find ways of saving ener-gy.Appropriate reduction in fuel gas loading and partially shifting of the reforming load from theprimary to the secondary reformer by regulating the operating conditions can result in substantial en-ergy saving.Optimization calculations with various objective functions and constraints required areperformed.The optimization results may serve as guideline for plant operation and control.     

一种新的利用LNG冷能的回收油田伴生气凝液的工艺

A novel process to recovery natural gas liquids from oil field associated gas with liquefied natural gas (LNG)cryogenic energy utilization is proposed.Compared to the current electric refrigeration process,the proposed process uses the cryogenic energy of LNG and saves 62.6%of electricity.The proposed process recovers ethane, liquid petroleum gas(propane and butane)and heavier hydrocarbons,with total recovery rate of natural gas liquids up to 96.8%.In this paper,exergy analysis and the energy utilization diagram method(EUD)are used to assess the new process and identify the key operation units with large exergy loss.The results show that exergy efficiency of the new process is 44.3%.Compared to the electric refrigeration process,exergy efficiency of the new process is improved by 16%.The proposed process has been applied and implemented in a conceptual design scheme of the cryogenic energy utilization for a 300 million tons/yr LNG receiving terminal in a northern Chinese harbor.     

Integration of coal pyrolysis process with iron ore reduction:Reduction behaviors of iron ore with benzene-containing coal pyrolysis gas as a reducing agent☆

An integrated coal pyrolysis process with iron ore reduction is proposed in this article. As the first step, iron oxide reduction is studied in a fixed bed reactor using simulated coal pyrolysis gas with benzene as a model tar compound. Variables such as reduction temperature, reduction time and benzene concentration are studied. The carbon deposition of benzene results in the retarded iron reduction at low temperatures. At high temperatures over800 °C, the presence of benzene in the gas can promote iron reduction. The metallization can reach up to 99% in20 min at 900 °C in the presence of benzene. Significant increases of hydrogen and CO/CO2 ratio are observed in the gas. It is indicated that iron reduction is accompanied by the reforming and decomposition of benzene. The degree of metallization and reduction increases with the increasing benzene concentration. Iron oxide can nearly completely be converted into cementite with benzene present in the gas under the experimental conditions. No sintering is found in the reduced sample with benzene in the gas.     

基于精细自由基反应机理的丙烷裂解炉炉管CFD模拟(英文)

In the radiant section of cracking furnace, the thermal cracking process is highly coupled with turbulent flow, heat transfer and mass transfer. In this paper, a three-dimensional simulation of propane pyrolysis reactor tube is performed based on a detailed kinetic radical cracking scheme, combined with a comprehensive rigorous computational fluid dynamics（CFD） model. The eddy-dissipation-concept（EDC） model is introduced to deal with turbulence-chemistry interaction of cracking gas, especially for the multi-step radical kinetics. Considering the high aspect ratio and severe gradient phenomenon, numerical strategies such as grid resolution and refinement, stepping method and relaxation technique at different levels are employed to accelerate convergence. Large scale of radial nonuniformity in the vicinity of the tube wall is investigated. Spatial distributions of each radical reaction rate are first studied, and made it possible to identify the dominant elementary reactions. Additionally, a series of operating conditions including the feedstock feed rate, wall temperature profile and heat flux profile towards the reactor tubes are investigated. The obtained results can be used as scientific guide for further technical retrofit and operation optimization aiming at high conversion and selectivity of pyrolysis process.     

天然气分散制氢的技术经济分析(英文)

It is well established that hydrogen has the potential to make a significant contribution to the world energy production.In U.S.,majority of hydrogen production plants implement steam methane reforming(SMR) for centralized hydrogen production.However,there is a wide lack of agreement on the nascent stage of using hydrogen as fuel in vehicles industry because of the difficulty in delivery and storage.By performing technological and economic analysis,this work aims to establish the most feasible hydrogen production pathway for automotives in near future.From the evaluation,processes such as thermal cracking of ammonia and centralized hydrogen production followed by bulk delivery are eliminated while on-site steam reforming of methanol and natural gas are the most technologically feasible options.These two processes are further evaluated by comprehensive economic analysis.The results showed that the steam reforming(SR) of natural gas has a shorter payback time and a higher return on investment(ROI) and internal rate of return(IRR).Sensitivity analysis has also been constructed to evaluate the impact of variables like NG feedstock price,capital of investment and operating capacity factor on the overall production cost of hydrogen.Based on this study,natural gas is prompted to be the most economically and technologically available raw material for short-term hydrogen production before the transition to renewable energy source such as solar energy,biomass and wind power.     

利用吸收-水合耦合法从氨弛放气中回收氢气的研究(英文)

In this work, the absorption-hydration hybrid method was used to recover (hydrogen + nitrogen) from (hydrogen + nitrogen + methane + argon) tail gas mixtures of synthetic ammonia plant through hydrate forma-tion/dissociation. A high-pressure reactor with magnetic stirrer was used to study the separation efficiency. The in-fluences of the concentration of anti-agglomerant, temperature, pressure, initial gas-liquid volume ratio, and oil-water volume ratio on the separation efficiency were systematically investigated in the presence of tetrahydro-furan (THF). Anti-agglomerant was used to disperse hydrate particles into the condensate phase for water-in-oil emulsion system. Since nitrogen is the material for ammonia production, the objective production in our separation process is (hydrogen + nitrogen). Our experimental results show that by adopting appropriate operating conditions, high concentration of (hydrogen + nitrogen) can be obtained using the proposed technology based on forming hydrate.     

带增湿区的质子交换膜燃料电池

Water management is of great importance to maintain performance and durability of proton exchange membrane fuel cells. This paper presents a novel proton exchange membrane (PEM) fuel cell with a humidification zone in the membrane electrode assembly (MEA) of each cell, in which the moisture of the cathode exhaust gas could transfer through the membrane to humidify anode or cathode dry gas. With a simple model, the relative humidity (RH) of the dry air exhaust from a membrane humidifier with 100% RH stream as a counter flow is calculated to be 60.0%, which is very close to the experimental result (62.2%). Fuel cell performances with hydrogen humidifying, air humidifying and no humidifying are compared at 50, 60 and 70˚C and the results indicate that humidifying is necessary and the novel design with humidifying zone in MEA is effective to humidify dry reactants. The hydrogen humidifying shows better performance in short term, while water recovered is limited and the stability is not as good as air hu-midifying. It is recommended that both air and hydrogen should be humidified with proper design of the humidifying zones in MEA and plates.     

SBR工艺除磷过程与种群结构在线监测

For efficient energy consumption and control of effluent quality, the cycle duration for a sequencing batch reactor (SBR) needs to be adjusted by real-time control according to the characteristics and loading of wastewater. In this study, an on-line information system for phosphorus removal processes was established. Based on the analysis for four systems with different ecological community structures and two operation modes, anaerobic-aerobic process and anaerobic-anaerobic process, the characteristic patterns of oxidation-reduction potential (ORP) and pH were related to phosphorous dynamics in the anaerobic, anoxic and aerobic phases, for determination of the end of phosphorous removal. In the operation mode of anaerobic-aerobic process, the pH profile in the anaerobic phase was used to estimate the relative amount of phosphorous accumulating organisms (PAOs) and glycogen accumulating organisms (GAOs), which is beneficial to early detection of ecology community shifts. The on-line sensor values of pH and ORP may be used as the parameters to adjust the duration for phosphorous removal and community shifts to cope with influent variations and maintain appropriate operation conditions.     

基于硫酸钙固体燃料化学链气化过程制备合成气的研究(英文)

Chemical-looping gasification (CLG) is a novel process for syngas generation from solid fuels,sharing the same basic principles as chemical-looping combustion (CLC).It also uses oxygen carriers (mainly metal oxide and calcium sulfate) to transfer heat and oxygen to the fuel.In this paper,the primary investigation into the CLG process with CaSO4 as oxygen carrier was carried out by thermodynamic analysis and experiments in the tube reactor.Sulfur-contained gas emission was mainly H2S rather than SO2 in the CLG process,showing some different features from the CLC.The mass and heat balance of CLG processes were calculated thermodynamically to determinate the auto-thermal operating conditions with different CaSO4/C and steam/C molar ratios.It was found that the CaSO4/C molar ratio should be higher than 0.2 to reach auto-thermal balance.The effect of temperature on the reactions between oxygen carrier and coal was investigated based on Gibbs free energy minimum method and experimental results.It indicated that high temperature favored the CLG process in the fuel reactor and part of syngas was consumed to compensate for auto-thermal system.     

Characterization and optimization of an autothermal diesel and jet fuel reformer for 5 kWe mobile fuel cell applications

The present paper describes the characterization of an autothermal reformer designed to generate hydrogen by autothermal reforming (ATR) from commercial diesel fuel (～10 ppm S) and jet fuel (～200 ppm S) for a 5 kW_e polymer electrolyte fuel cell (PEFC). Commercial noble metal-based catalysts supported on 900 cpsi cordierite monoliths substrates were used for ATR with reproducible results. Parameters investigated in this study were the variation of the fuel inlet temperature, fuel flow and the H₂O/C and O₂/C ratios. Temperature profiles were studied both in the axial and radial directions of the reformer. Product gas composition was analyzed using gas chromatography.It was concluded from the experiments that an elevated fuel inlet temperature (≥60 °C) and a higher degree of fuel dispersion, generated via a single-fluid pressurized-swirl nozzle at high fuel flow, significantly improved the performance of the reformer. Complete fuel conversion, a reforming efficiency of 81% and an H₂ selectivity of 96% were established for ATR of diesel at P = 5 kW_e, H₂O/C = 2.5, O₂/C = 0.49 and a fuel inlet temperature of 60 °C. No hot-spot formation and negligible coke formation were observed in the reactor at these operating conditions. The reforming of jet fuel resulted in a reforming efficiency of only 42%. A plausible cause is the coke deposition, originating from the aromatics present in the fuel, and the adsorption of S-compounds on the active sites of the reforming catalyst.Our results indicate possibilities for the developed catalytic reformer to be used in mobile fuel cell applications for energy-efficient hydrogen production from diesel fuel.     

Fuel processing in direct propane solid oxide fuel cell and carbon dioxide reforming of propane over Ni-YSZ

This work is aimed at understanding the reaction mechanism of propane internal reforming in the solid oxide fuel cell (SOFC). This mechanism is important for the design and operation of SOFC internal processing of hydrocarbons. An anode-supported SOFC unit with Ni-YSZ anode operating at 800 °C was tested with direct feeding of 5% propane. CO₂ reforming of propane was carried out in a reactor with Ni-YSZ catalyst to simulate internal propane processing in SOFC. The performance of this direct propane SOFC is stable. The C specie formed over the anode functional layer of SOFC can be completely removed. The major gas products of SOFC are H₂, CO, CH₄, C₂H₄ and CO₂. Pseudo-steady-state internal processing of propane in the anode catalytic layer of SOFC is associated with a CO₂/C₃H₈ molar ratio of about 1.26 and basically CO₂ reforming of propane. CO₂ dissociation to produce the O species to oxidize the C species from dehydrogenation and dissociation of propane and its fragments should be the major reaction during CO₂ reforming of propane.     

Development of a Combined Plasma-Matrix Reformer for Solid Oxide Fuel Cell Application

A novel plasma-matrix reformer (PMR) was suggested for methane conversion into hydrogen-rich fuel. To demonstrate the possibility of reforming performance, characteristics of product gas and CH₄ conversion were identified according to O₂/C ratio, water vapor supply, reformed gas recirculation, and water feed in the recirculation gas affecting energy conversion and hydrogen production. When the reformed gas recirculation and water feed to the recirculation pipe were performed at the same time, hydrogen production and energy conversion efficiency were superior compared to the conventional reforming method. The optimal operating conditions of the PMR were determined. The obtained high energy conversion efficiency and hydrogen selectivity indicated the applicability to solid oxide fuel cell stacks for residential power generation.     

Propane conversion over a Ru/CGO catalyst and its application in intermediate temperature solid oxide fuel cells

A Ru/CGO catalyst was investigated in combination with a Cu current collector for the direct electro-oxidation and internal reforming of propane in a solid oxide fuel cell. The electrochemical power densities for the direct oxidation were larger than in the internal reforming process at 750 °C. The electrochemical performance in the presence of propane was significantly affected by the polarization resistance which was about three times larger than that obtained for the SOFC fed with hydrogen at 750 °C. However, out-of-cell steam reforming tests showed a C₃H₈ conversion to syngas approaching 90% at 800 °C. Thus, significant enhancements may be achieved by properly optimizing the anode structure. No formation of carbon deposits was observed both upon operation of the anode in the direct oxidation and internal reforming processes at 750 °C.     

Production of hydrogen-rich gas via reforming of iso-octane over Ni–Mn and Rh–Ce bimetallic catalysts using spray pulsed reactor

The conversion of hydrocarbon fuels such as gasoline and diesel is a potential source for hydrogen production towards various fuel cell systems. A novel spray pulsed mode reactor to create alternate wet and dry conditions on the catalyst surface has been used in this study to enhance the rates of hydrogen production compared with the solid-gas phase reaction due to the improvement of the catalyst reactant contact. The production of hydrogen-rich gas by reforming of iso-octane (2,2,4-trimethylepentane) in the presence of steam and air has been studied at 600 and 700 °C over Ni–Mn and Rh–Ce bimetallic catalysts supported on alumina mesh. The feed rate of iso-octane was varied from 0.553 to 5.53 m mol min^–1 by controlling pulse injection in terms of the width and frequency of injection of iso-octane. Based on the product analysis optimized condition for higher hydrogen production and high H₂/CO ratio has been deduced.     

Ru-catalyzed anode materials for direct hydrocarbon SOFCs

A solid oxide fuel cell using a thin ceria-based electrolyte film with a Ru-catalyzed anode was directly operated on hydrocarbons, including methane, ethane, and propane, at 600 °C. The role of the Ru catalyst in the anode reaction was to promote the reforming reaction of the unreacted hydrocarbons by the produced steam and CO₂, which avoided interference from steam and CO₂ in the gas-phase diffusion of the fuels. The resulting peak power density reached 750 mW cm⁻² with dry methane, which was comparable to the peak power density of 769 mW cm⁻² with wet (2.9 vol.% H₂O) hydrogen. More important was the fact that the cell performance was maintained at a high level regardless of the change in the methane utilization from 12 to 46% but was significantly reduced by increasing the hydrogen utilization from 13 to 42%. While the anodic reaction of hydrogen was controlled by the slow gas diffusion, the anodic reaction of methane was not subject to the onset of such a gas-diffusion process.     

The micro-reactor testing of catalysts and fuel delivery apparatuses for diesel autothermal reforming

This study investigated two factors affecting the performance of diesel autothermal reforming (ATR): the reforming activity of selected catalysts and the effect of devised fuel delivery apparatuses. When fluorite and perovskite-structured ceramic materials were used as substrates, H₂ yields were higher than when an inert Al₂O₃ substrate was used at 700–800 °C. Gadolinium (Gd)-doped CeO₂ (CGO) had the highest H₂ production rate in the selected substrates. Platinum (Pt) showed better performance than rhodium (Rh) and ruthenium (Ru) when CGO was used as the substrate. Although the nickel (Ni)-added Pt catalyst (Pt–Ni) showed high H₂ yield, carbon deposition over this catalyst was more severe than with Pt. Oxygen ion (O²⁻) vacancies generated by Gd dopants can enhance the reforming activity of CeO₂. When using a microchannel catalyst bed, the performance degradation at high gas flowrates can be compared to a packed catalyst bed of pellet type. For effective fuel delivery, we have introduced an ultrasonic injector (UI) and a plasma injector (PI). The UI-reforming showed greater long-term stability than non-UI reforming because the generation of carbon precursors was suppressed. On the other hand, the PI-reformer had low conversion efficiency, although it had high H₂ selectivity.     

A Multi‐Function Compact Micro‐Channel Reactor Coated with Sulphur Tolerant Catalyst for LPG Steam Reforming

Hydrogen fuelled polymer electrolyte fuel cells (PEFC) offer clear environmental benefits. Lack of viable hydrogen infrastructure in the near future means that a key issue is availability of hydrogen at the point of use. Liquefied petroleum gas (LPG) offers advantages as a fuel over other hydrocarbons because there is already an infrastructure in place for remote areas. Hydrogen supply via steam reforming of LPG is therefore a feasible avenue of achieving the environmental benefits. Commercial grade LPG unavoidably contain sulphur as an odorant, the sulphur needs to be removed from the fuel stream before it reaches the reformer catalyst and fuel cell. Utilizing sulphur tolerant catalysts in the reformer leads to a simpler fuel processor design. Thermal management and reforming efficiency has been a challenge for the sulphur tolerant catalysts. In this paper, a multi‐function compact micro‐channel reactor designed for hydrocarbon steam reforming was evaluated for use with LPG. A sulphur tolerant catalyst was wash‐coated on to the reforming layers. The reformer was tested over a wide range of reactor temperatures, steam to carbon ratios and fuel flow rates. Over 60% of H₂ composition can be achieved at high reforming temperatures with a LPG supply rate of 0.75 dm³ min⁻¹ (STP) and a S/C ratio of 4.     

Thermodynamic study of combining chemical looping combustion and combined reforming of propane

Existing energy generation technologies emit CO₂ gas and are posing a serious problem of global warming and climate change. The thermodynamic feasibility of a new process scheme combining chemical looping combustion (CLC) and combined reforming (CR) of propane (LPG) is studied in this paper. The study of CLC of propane with CaSO₄ as oxygen carrier shows thermodynamic feasibility in temperature range (400-782.95 °C) at 1 bar pressure. The CO₂ generated in the CLC can be used for combined reforming of propane in an autothermal way within the temperature range (400-1000 °C) at 1 bar pressure to generate syngas of ratio 3.0 (above 600 °C) which is extremely desirable for petrochemical manufacture. The process scheme generates (a) huge thermal energy in CLC that can be used for various processes, (b) pure N₂ and syngas rich streams can be used for petrochemical manufacture and (c) takes care of the expensive CO₂ separation from flue gas stream and CO₂ sequestration. The thermoneutral temperature (TNP) of 702.12 °C yielding maximum syngas of 5.98 mol per mole propane fed, of syngas ratio 1.73 with negligible methane and carbon formation was identified as the best condition for the CR reactor operation. The process can be used for different fuels and oxygen carriers.