Current status of national integrated gasification fuel cell projects in China

Coal has been the main energy source in China for a long period.Therefore,the energy industry must improve coal power generation efficiency and achieve near-zero CO_(2) emissions.Integrated gasification fuel cell(IGFC)systems that combine coal gasification and high-temperature fuel cells,such as solid oxide fuel cells or molten carbonate fuel cells(MCFCs),are proving to be promising for efficient and clean power generation,compared with traditional coal-fired power plants.In 2017,with the support of National Key R&D Program of China,a consortium led by the China Energy Group and including 12 institutions was formed to develop the advanced IGFC technology with near-zero CO_(2) emissions.The objectives of this project include understanding the performance of an IGFC power generation system under different operating conditions,designing master system principles for engineering optimization,developing key technologies and intellectual property portfolios,setting up supply chains for key materials and equipment,and operating the first megawatt IGFC demonstration system with near-zero CO_(2) emission,in early 2022.In this paper,the main developments and projections pertaining to the IGFC project are highlighted.

Hydrate-based carbon dioxide capture from simulated integrated gasification combined cycle gas

The equilibrium hydrate formation conditions for CO2/H2 gas mixtures with different CO2 concentrations in 0.29 mol% TBAB aqueous solution are firstly measured.The results illustrate that the equilibrium hydrate formation pressure increases remarkably with the decrease of CO2 concentration in the gas mixture.Based on the phase equilibrium data,a three stages hydrate CO2 separation from integrated gasification combined cycle （IGCC） synthesis gas is investigated.Because the separation efficiency is quite low for the third hydrate separation,a hybrid CO2 separation process of two hydrate stages in conjunction with one chemical absorption process （absorption with MEA） is proposed and studied.The experimental results show H2 concentration in the final residual gas released from the three stages hydrate CO2 separation process was approximately 95.0 mol% while that released from the hybrid CO2 separation process was approximately 99.4 mol%.Thus,the hybrid process is possible to be a promising technology for the industrial application in the future.

Status of an MWth integrated gasification fuel cell powergeneration system in China

Abstract Here,we provide a status update of an integrated gasification fuel cell(IGFC)power-generation system being developed at the National Institute of Clean-and-Low-Carbon in China at the megawatt thermal(MWth)scale.This system is designed to use coal as fuel to produce syngas as a first step,similar to that employed for the integrated gasification combined cycle.Subsequently,the solid-oxide fuel-cell(SOFC)system is used to convert chemical energy to electricity directly through an electrochemical reaction without combustion.This system leads to higher efficiency as compared with that from a traditional coal-fired power plant.The unreacted fuel in the SOFC system is transported to an oxygencombustor to be converted to steam and carbon dioxide(CO_(2)).Through a heat-recovery system,the steam is condensed and removed,and CO_(2) is enriched and captured for sequestration or utilization.Comprehensive economic analyses for a typical IGFC system was performed and the results were compared with those for a supercritical pulverized coal-fired power plant.The SOFC stacks selected for IGFC development were tested and qualified under hydrogen and simulated coal syngas fuel.Experimental results using SOFC stacks and thermodynamic analyses indicated that the control of hydrogen/CO ratio of syngas and steam/CO ratio is important to avoid carbon deposition with the fuel pipe.A 20-kW SOFC unit is under development with design power output of 20 kW and DC efficiency of 50.41%.A 100 kW-level subsystem will consist of 6920-kW power-generation units,and the MWth IGFC system will consist of 59100 kWlevel subsystems.

Key CO_(2)capture technology of pure oxygen exhaust gas combustion for syngas-fueled high-temperature fuel cells

Integrated gasification fuel cells(IGFCs)integrating high-temperature solid oxide fuel cell technology with CO_(2)capture processes represents highly-efficient power systems with negligible CO_(2)emissions.Flame burning with pure oxygen is an ideal method for fuel cell exhaust gas treatment,and this report describes experimental and numerical studies regarding an oxy-combustor for treating the exhaust gas of a 10 kW IGFC system anode.The applied simulation method was verified based on experiments,and the key performance indices of the combustor were studied under various conditions.It was determined that 315 K was the ideal condensation temperature to obtain flame stability.Under these pure oxygen flame burning conditions,CO was almost completely converted,and the dry mole fraction of CO_(2)after burning was C 0.958 when there was up to 5%excess O_(2).Overall,5%excess O_(2)was recommended to maximize CO_(2)capture and promote other environmental considerations.Additionally,the optimal tangential fuel jet angle to control the liner temperature was approximately 25°.The total fuel utilization had to be high enough to maintain the oxygen flame temperature of the anode exhaust gas below 1800 K to ensure that the system was environmentally friendly.The results presented herein have great value for designing IGFCs coupled with CO_(2)capture systems.

Development of catalytic combustion and CO_(2)capture and conversion technology

Changes are needed to improve the efficiency and lower the CO_(2)emissions of traditional coal-fired power generation,which is the main source of global CO_(2)emissions.The integrated gasification fuel cell(IGFC)process,which combines coal gasification and high-temperature fuel cells,was proposed in 2017 to improve the efficiency of coal-based power generation and reduce CO_(2)emissions.Supported by the National Key R&D Program of China,the IGFC for nearzero CO_(2)emissions program was enacted with the goal of achieving near-zero CO_(2)emissions based on(1)catalytic combustion of the flue gas from solid oxide fuel cell(SOFC)stacks and(2)CO_(2)conversion using solid oxide electrolysis cells(SOECs).In this work,we investigated a kW-level catalytic combustion burner and SOEC stack,evaluated the electrochemical performance of the SOEC stack in H2O electrolysis and H2O/CO_(2)co-electrolysis,and established a multiscale and multi-physical coupling simulation model of SOFCs and SOECs.The process developed in this work paves the way for the demonstration and deployment of IGFC technology in the future.

Effect of binder on the properties of iron oxide sorbent for hot gas desulfurization

The most difficult problem in hot gas desulfurization in Integrated Coal Gasification Combined Cycle （IGCC） is the pulverization of sulfur removal sorbents.Appropriate binders for hot gas sulfur removal sorbents can solve the pulverization problem.In this paper,six sorbents with binders of different argillaceous minerals were prepared by mechanical mixing method.Desulfurization behavior for hot gas desulfurization sorbents was investigated in a fixed-bed reactor.Result showed that sorbent NTKW2 with binder of clay had a better sulfidation performance.NTKW2 had a more stable performance than other sorbents in the continuous sulfidation-regeneration cycles.Sulfur capacity of sorbent remained the same in each cycle.The desulfurization efficiency and mechanical strength of NTKW2 were the best among the tested sorbents.The behavior of NTKW2 at different temperatures showed different performances,and the best reaction temperature was 550 ℃.Higher heat stability,sulfur capacity and desulfurization efficiency were found on NTKW2 in six continuous sulfidation-regeneration cycles.

Performance test of a 5 kW solid oxide fuel cell system under high fuel utilization with industrial fuel gas feeding

As the demand for green energy with high efficiency and low carbon dioxide(CO2)emissions has increased,solid oxide fuel cells(SOFCs)have been intensively developed in recent years.Integrated gasification fuel cells(IGFCs)in particular show potential for large-scale power generation to further increase system efficiency.Thus,for commercial application of IGFCs,it is important to design reliable multi-stacks for large systems that show long-term stability and practical fuel gas for application to industrial equipment.In this work,a test rig(of a 5 kW SOFC system,with syngas from industrial gasifiers as fuel)was fabricated and subjected to long-term tests under high fuel utilization to investigate its performance.The maximum steady output power of the system was 5700 W using hydrogen and 5660 W using syngas and the maximum steady electrical efficiency was 61.24%while the fuel utilization efficiency was 89.25%.The test lasted for more than 500 h as the fuel utilization efficiency was larger than 83%.The performances of each stack tower were almost identical at both the initial stage and after long-term operation.After 500 h operation,the performances of the stack towers decreased only slightly under lower current and showed almost no change under high current.These results demonstrate the reliability of the multi-stack design and the prospect of this SOFC power-generation system for further enlarging its application in a MWth demonstration.

Techno-economic assessment of pulverized coal boilers and IGCC power plants with CO_(2) capture

The current studies on power plant technologies suggest that Integrated Gasification Combined Cycle(IGCC)systems are an effective and economic CO_(2) capture technology pathway.In addition,the system in conventional configuration has the advantage of being more“CO_(2) capture ready”than other technologies.Pulverized coal boilers(PC)have,however,proven high technical performance attributes and are economically often most practical technologies.To highlight the pros and cons of both technologies in connection with an integrated CO_(2) capture,a comparative analysis of ultrasupercritical PC and IGCC is carried out in this paper.The technical design,the mass and energy balance and the system optimizations are implemented by using the ECLIPSE chemical plant simulation software package.Built upon these technologies,the CO_(2) capture facilities are incorporated within the system.The most appropriate CO_(2) capture systems for the PC system selected for this work are the oxy-fuel system and the postcombustion scheme using Monoethanolamine solvent scrubber column(MEA).The IGCC systems are designed in two configurations:Water gas shift reactor and Selexol-based separation.Both options generate CO_(2)-rich and hydrogen rich-gas streams.Following the comparative analysis of the technical performance attributes of the above cycles,the economic assessment is carried out using the economic toolbox of ECLIPSE is seamlessly connected to the results of the mass and energy balance as well as the utility usages.The total cost assessment is implemented according to the stepcount exponential costing method using the dominant factors and/or a combination of parameters.Subsequently,based on a set of assumptions,the net present value estimation is implemented to calculate the breakeven electricity selling prices and the CO_(2) avoidance cost.

Conceptual Process and Analysis of Water-Gas-Shift Membrane Reactor

A new conceptual water-gas-shift(WGS) process is designed for integrated gasification combined cycle(IGCC), using membrane reactor(MR) equipped with H2-permselective zeolite membranes for the WGS reaction.The new process makes it possible to capture CO2 before power generation process by converting CO in the syngas to CO2 which can be collected after WGS reaction. The new process also produces purer H2 for combustion in gas turbine. Conceptual design of the MR, mass and heat balance analysis, and cost estimation of the new process are also provided in this paper.