Integrated Gasification Combined Cycle Research Articles

Research and development of high efficiency low emission combined cycle power plant arrangements

Coal-fired steam turbine thermal power plants produce a large part of electricity. These power plants usually have low efficiency and high carbon dioxide emission. An application of combined cycle power plants with coal gasification equipped with carbon capture and storage systems may increase the efficiency and decrease the harmful emission. This paper describes investigation of the oxidizer type in the integrated gasification combined cycle combustion chamber and its influence upon the energy and environmental performance. The integrated gasification combined cycle and oxy-fuel combustion technology allow the carbon dioxide capture and storage losses 58% smaller than the traditional air combustion one. The IGCC with air combustion without and with carbon dioxide capture and storage has 53.54 and 46.61% and with oxy-fuel combustion has 34.94 and 32.67% net efficiency. Together with this the CO2 emission drops down from 89.9 to 10.6 gm/kWh. The integrated coal gasification combined cycle with air oxidizer has the best net efficiency.

Simulating optimal development of clean coal-fired power generation for collaborative reduction of air pollutant and CO2 emissions

Over 60% of electricity was produced by coal-fired power plants in China. Apart from accelerating penetration of non-fossil power, clean coal-fired power generation (CCFPG) needs to be largely impelled. The economic and environmental impacts of expanded development of CCFPG industry within the socioeconomic system remain unclear. We develop an integrated input-output model to explore an optimal combination of CCFPG technologies subject to emission constraints and maximization of gross regional production. The trends in CCFPG industries’ outputs and power generation, as well as reductions of NO x , SO 2 , PM 2.5 and CO 2 emissions in Jilin Province during 2021–2030 are simulated in seven scenarios. We found that the timing and scale of development of CCFPG technologies are mainly determined by costs, joint-removal efficiencies, and levels of emission constraints. When CO 2 emission constraint gets stricter, the production of integrated gasification combined cycle with carbon capture and storage will increase for larger CO 2 emission reduction. Industrialization of CCFPG technologies calls for additional investment and subsidies, which would induce reduced investment for some sectors and negative impact on the economy. The quantified economic and environmental impacts of introducing CCFPG technologies are expected to provide government with references for emission mitigation of coal-fired power generation industries.

Life cycle meta-analysis of carbon capture pathways in power plants: Implications for bioenergy with carbon capture and storage

Bioenergy with carbon capture and storage (BECCS) based electricity generation is one possible approach for delivering large-scale carbon dioxide removal from the atmosphere. This study evaluates the environmental impacts of leveraging existing power plants for BECCS. We performed a life cycle meta-analysis of eight carbon capture technologies, including five previously simulated only for coal and natural gas, for both steam cycle and integrated gasification combined cycle (IGCC) power plants. We found that IGCC plants offer the best balance of negative emissions, energy return on investment (EROI) and low water use irrespective of capture technologies. Planned IGCC plants tend to be large whereas biomass-fired power plants are often small and distributed in the landscape because of the distributed nature of the fuel. Steam cycle plants had larger negative emissions, but also lower EROI, and so blending with coal may be necessary to achieve a suitable EROI. Steam cycles were sensitive to capture technology type, and results found membrane and calcium looping capture technologies offer a balance between negative emissions, EROI and water use when fired using coal-biomass blends. These results suggest that steam cycle power plants may be the most desirable candidates to support early-stage deployment of BECCS.

Investigation on the Cause of the SO2 Generation during Hot Gas Desulfurization (HGD) Process

In the integrated gasification combined cycle (IGCC) process, the sulfur compounds present in coal are converted to hydrogen sulfide (H2S) when the coal is gasified. Due to its harmful effects on sorbent/solvent and environmental regulations, H2S needs to be removed from the product gas stream. To simulate the H2S removal process, desulfurization was carried out using a dry sorbent as a fluidizing material within a bubbling, high-temperature fluidized bed reactor. The ZnO-based sorbent showed not only an excellent capacity of H2S removal but also long-term stability. However, unexpected SO2 gas at a concentration of several hundred ppm was detected during the desulfurization reaction. Thus, we determined that there is an unknown source that supplies oxygen to ZnS, and identified the oxygen supplier through three possibilities: oxygen by reactant (fresh sorbent, ZnO), byproduct (ZnSO4), and product (H2O). From the experiment results, we found that the H2O produced from the reaction reacts with ZnS, resulting in SO2 gas being generated during desulfurization. The unknown oxygen source during desulfurization was deduced to be oxygen from H2O produced during desulfurization. That is, the oxygen from produced H2O reacts with ZnS, leading to SO2 generation at high temperature.

Techno-Economic Assessment of IGCC Power Plants Using Gas Switching Technology to Minimize the Energy Penalty of CO2 Capture

Cost-effective CO2 capture and storage (CCS) is critical for the rapid global decarbonization effort recommended by climate science. The increase in levelized cost of electricity (LCOE) of plants with CCS is primarily associated to the large energy penalty involved in CO2 capture. This study therefore evaluates three high-efficiency CCS concepts based on integrated gasification combined cycles (IGCC): (1) gas switching combustion (GSC), (2) GSC with added natural gas firing (GSC-AF) to increase the turbine inlet temperature, and (3) oxygen production pre-combustion (OPPC) that replaces the air separation unit (ASU) with more efficient gas switching oxygen production (GSOP) reactors. Relative to a supercritical pulverized coal benchmark, these options returned CO2 avoidance costs of 37.8, 22.4 and 37.5 €/ton (including CO2 transport and storage), respectively. Thus, despite the higher fuel cost and emissions associated with added natural gas firing, the GSC-AF configuration emerged as the most promising solution. This advantage is maintained even at CO2 prices of 100 €/ton, after which hydrogen firing can be used to avoid further CO2 cost escalations. The GSC-AF case also shows lower sensitivity to uncertain economic parameters such as discount rate and capacity factor, outperforms other clean energy benchmarks, offers flexibility benefits for balancing wind and solar power, and can achieve significant further performance gains from the use of more advanced gas turbine technology. Based on all these insights, the GSC-AF configuration is identified as a promising solution for further development.

A cadmium-magnesium looping for stable thermochemical energy storage and CO2 capture at intermediate temperatures

Thermochemical energy storage (TCES) based on the carbonation/decarbonation cycle of metal oxide/carbonate is an attractive technology to address the intermittent problems of renewable energy and to recover industrial waste heat. The alkali metal salt-promoted MgO-based sorbent materials are promising for TCES at intermediate temperatures but suffer from severe thermal instability owing to the high decarbonation temperature of MgCO3 in pure CO2. In this study, we for the first time reported a novel Cd-Mg looping whereby CdO and MgCO3 with the aid of molten NaNO3 can be rapidly and reversibly converted into CdMg(CO3)2 through carbonation/partial decarbonation, which enabled a low working temperature and thus enhanced the stability of the NaNO3-promoted Cd-Mg containing materials. The effect of Cd/Mg atomic ratio on the property, activity and stability of the materials was systematically studied; moreover, the carbonation/decarbonation mechanism was carefully explored. The promising candidate containing equimolar amounts of Cd and Mg can not only perform stable intermediate-temperature TCES in 100 cycles, but also convert the low-concentration waste CO2 in integrated gasification combined cycle power plants into pure CO2. These findings offer new opportunities for TCES and CO2 capture at intermediate temperatures.

An overview of biofuel power generation on policies and finance environment, applied biofuels, device and performance

The prices of fossil fuels, the gap between energy supply and demand, energy security, environmental issues, and the reduction of greenhouse gas emissions commonly promote the development of biomass power generation in China. Compared to direct biomass combustion power generation and biogas power generation, liquid biofuel power generation has better application potential. Policies and finance environment of countries and organizations have promoted the extensive application of biofuel power generation in recent years, especially in China. Evaluation of internal combustion engine, gas turbine and fuel cell on the stationary power station and mobile generation shows that gas turbine is the main generator-set, the fuel cell is the fastest-growing and future generator-set, while the engine is the first choice in transport and low power generation field. As the second, third and fourth generation biofuels, biomethanol, bioethanol, biodiesel and others have been researched and widely used in power generation. In addition, power generation performance and emissions have been improved to some extent after biofuels supplying. For the future, combined heat and power (CHP) generation and integrated gasification combined cycle (IGCC) is imperative development trends of power generation for higher energy and exergy efficiency. CHP based on the various generating facilities will be the next choice and direction of energy use trends for transport.

Techno-environmental-economic evaluation on municipal solid waste (MSW) to power/fuel by gasification-based and incineration-based routes

The energy cascade utilization of municipal solid waste (MSW) is an important subject to realize sustainable development. The gasification-based option has shown great potential in resource recovery with high-efficiency conversion. In this study, the techno-environmental-economic performance of Waste-to-Power (WtP) and Waste-to-Fuel (WtF) technologies, including MSW integrated gasification combined cycle (MIGCC), MSW-to-hydrogen (MTH), MSW-to-synthetic natural gas (MTNG) and MSW incineration to energy (MTE), is analyzed and evaluated based on the Aspen Plus simulation. The results show that MTH process owns the highest exergy efficiency with 46.7%, followed by MTNG (43.7%), MIGCC (28.6%) and MTE (18.9%). The MTH and MTNG processes appear to be more environmentally friendly than MTE in terms of global warming potential (GWP). The levelized profit of MSW (LPOM) for MIGCC process is the lowest under current market conditions. By comparison, the MTH process exhibits the best economic performance in resisting the fluctuation of electricity sales tariff, carbon tax and MSW subsidy price. In addition, MTH process could be regarded as a promising alternative path to produce hydrogen because of its economic advantage than coal-to-hydrogen and biomass-to-hydrogen processes.

Biomass direct gasification for electricity generation and natural gas replacement in the lime kilns of the pulp and paper industry: A techno-economic analysis

This study shows a comparative techno-economic analysis of the integration of biomass gasification for generation of producer gas to be used in electricity production and to replace natural gas in the lime kilns of the pulp and paper industry. Three study cases with alternative configurations of the energy system integrating biomass gasification were analysed, including or not the co-generation of electricity and thermal energy, namely: i) Case I, for generation of electricity from residual forest biomass (RFB) in an integrated gasification combined cycle system, ii) Case II, generation of producer gas by RFB gasification for replacement of natural gas in the burners of a lime kiln, and iii) Case III, as an integration of Cases I and II for combined production of electricity and heat. Residual forest biomass from eucalyptus logging activities for feedstock processing for the pulp and paper industry was considered as fuel for direct (air) gasification in bubbling fluidized bed. The analysis made is supported on review reports, namely, the evaluation of the existing literature on investment projects in biomass power plants, and on experimental investigation for determining the composition of the producer gas from gasification of the selected feedstock. An economic model was developed that combines the net present value, internal rate of return and payback period. The main results of the energy system analysis show that the net electricity generation is between 72 and 83 GWh/year, while the production of CaO in the lime kiln supported by combustion of producer gas, is 82.12 kt/year, and a global energy efficiency between 21.70 and 34.17 % is achieved for the analysed configurations of the energy system. The results of the economic analysis show a positive NPV, an IRR greater than the discount rate and a PBP less than the useful life of the plant. The sensitivity analysis shows quite favorable investment projections given the low probability that the NPV will reach negative values and compromise the economic viability of the project.

Coupling chemical looping combustion of solid fuels with advanced steam cycles for CO2 capture: A process modelling study

Chemical looping combustion is a cost-competitive solution for producing low carbon electricity. In this paper, we investigate by means of a process modelling study, the coupling of chemical looping combustion of solid fuels with advanced steam-based power cycles, viz. supercritical, ultra-supercritical and advanced ultra-supercritical Rankine cycles. The energy and exergy efficiencies of the various chemical looping combustion power plant configurations are compared against the reference plants without carbon capture. Our models incorporate practical considerations for reactor design. With an upper operating temperature limit of 950 °C, the maximum efficiencies achievable by integrated gasification combined cycle chemical looping combustion (IGCC–CLC) and in situ gasification chemical looping combustion power plants (iG-CLC) are 41.3% and 41.5%, respectively. Overall, iG-CLC emerges as the most efficient CLC configuration. Comparing to an integrated gasification combined cycle without carbon capture, the energy efficiency penalties for capturing CO2 from iG-CLC coupled with subcritical, supercritical, ultra-supercritical or advanced ultra-supercritical steam cycles are 5.1%, 5.0%, 5.2% or 13.0%, respectively. The biomass-fired chemical looping combustion power plants also show low energy efficiency penalties (<2.5%) compared to the reference biomass power plants without CO2 capture. Our modelling results suggest that chemical looping combustion will remain an attractive carbon capture technology for solid fuel power plants, in a future when supercritical steam turbines become the norm.

Facilitated transport membranes for H2 purification from coal-derived syngas: A techno-economic analysis

A single-stage membrane process has been designed for using facilitated transport membranes (FTMs) to decarbonize the coal-derived syngas from an integrated gasification combined cycle (IGCC) power plant. The necessary process model and costing method have also been developed to assess the technical feasibility and process economics. In order to account for the carrier saturation phenomenon associated with FTMs, a homogeneous reactive diffusion model is integrated into the process model. The techno-economic study reveals that the mitigated carrier saturation upon bulk CO2 removal can lead to appreciable increases in the CO2 permeance and CO2/H2 selectivity, which can be utilized to achieve 95% CO2 purity and 95% H2 recovery with a CO2/H2 selectivity of 50 at the complete carrier saturation. FTMs with different facilitated transport characteristics can also be arranged in a hybrid membrane configuration to render a H2 recovery of 99% and a cost of electricity of $118.5/MWh, which is 12.5% lower than that of the benchmark Selexol process.

A Novel Electricity and Freshwater Production System: Performance Analysis from Reliability and Exergoeconomic Viewpoints with Multi-Objective Optimization

Based on the benefits of integrated gasification combined cycles (IGCCs), a cogeneration plant for providing electricity and freshwater is proposed. The main novelties of the devised system are the integration of biomass gasification and a regenerative gas turbine with intercooling and a syngas combustor, where the syngas produced in the gasifier is burned in the combustion chamber and fed to a gas turbine directly. The energy discharged from the gas turbine is utilized for further electricity and freshwater generation via Kalina and MED hybridization. The proposed system is analyzed from energy, exergy, exergoeconomic, and reliability–availability viewpoints. The optimal operating condition and optimum performance criteria are obtained by hybridizing an artificial neural network (ANN), the multi-objective particle swarm optimization (MOPSO) algorithm. According to results obtained, for the fourth scenario of the optimization process, optimal values of 45.10%, 14.27 kg·s−1, 12.95 USD·GJ−1, and 8141 kW are obtained for the exergy efficiency, freshwater production rate, sum unit cost of products, and net output power, respectively. According to reliability and availability assessment, the probability of the healthy working state of all components and subsystems is 88.4403%; the system is shown to be 87.74% available of the time over the 20-year lifetime.

Emergy evaluation of the integrated gasification combined cycle power generation systems with a carbon capture system

An Integrated Gasification Combined Cycle (IGCC) power generation system has a significant effect on improving resource utilization efficiency. Carbon capture and storage (CCS) has been widely adopted to control greenhouse gas emissions. The integration of the two systems can further reduce CO2 emissions but cause elevated investment costs. As an effective tool to evaluate resource utilization efficiency and environmental impact, emergy analysis on coal and biomass based IGCC power generation systems with/without CCS is conducted in this paper. The coal based IGCC systems are simulated in Aspen plus to obtain the electricity generated under different CCS scales. For other systems, the data for emergy evaluation are from references. The sustainabilities under different CO2 tax values are compared. The factors impacting the sustainabilities are discussed. The results show that when CCS is not considered, all IGCC systems are superior to coal and biomass direct-fired systems in terms of sustainability. After CCS is integrated, the sustainability of biomass based IGCC system is still higher than that of biomass direct-fired systems, while coal based IGCC systems are less sustainable than coal direct-fired systems under low CO2 tax. The sustainabilities of Texaco-IGCC systems increase with CCS scales when CO2 tax is higher than 0.0220 $/kg, emphasizing CCS at a larger scale. For the Shell-IGCC systems, a higher CO2 tax (0.3880 $/kg) is preferred for the promotion of large scale CCS. In the scenario that the cost emergy transformity improves, the CO2 tax value at the point of sustainabilities reversal will decrease.

Status of an MWth integrated gasification fuel cell power-generation system in China

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 oxygen-combustor to be converted to steam and carbon dioxide (CO2). Through a heat-recovery system, the steam is condensed and removed, and CO2 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 6 × 20-kW power-generation units, and the MWth IGFC system will consist of 5 × 100 kW-level subsystems.

Comparative environmental benefits of power generation from underground and surface coal gasification with carbon capture and storage

Underground gasification combined cycle (UGCC), when combined with carbon capture and storage (CCS), is widely judged to be a promising approach for clean coal utilization especially in the context of carbon neutral energy pathways. Nevertheless, the overall operation processes may consume a multiple of energy and inevitably trigger environmental concerns. Hence, a careful evaluation of the potential environmental impacts associated with UGCC is needed. In this study, we assessed environmental impacts of UGCC with and without CCS by the life cycle assessment method, and compared the results with those of surface integrated gasification combined cycle (IGCC) to gain better insight into tradeoffs of two coal gasification technologies and lighten the environmental burden by design optimizations. The results demonstrated that most mid-point impact values of UGCC power plants, which reflect pollution emissions and corresponding damage degree, were lower. Inversely, the global warming potential was 16.9% higher than those of IGCC power plants. Furthermore, UGCC power plants have superior end-point environmental benefits, which represent the damage of ecosystem quality, human health and resources. As demonstrated by the fact that the value of above three impact types were 23%, 15% and 4%, lower than those of IGCC power plants, respectively. In addition, the implement of CCS in two types of power plants decreased human health damage due to reduced greenhouse gas emissions, but notable environmental trade-offs are the increase in ecosystem quality damage and resource damage. The aggregated results show that UGCC with or without CCS has a more outstanding environmental performance with exception of global warming potential than IGCC with or without CCS. Enhancing UCG process control, improving syngas heating value and decreasing the energy in gasification agent preparation are effective methods to further reduce the GHG emissions. Approached in an improved way, UGCC-CCS stands to provide a low-carbon and self-contained solution for power production and energy provision.

Simulation of a new biomass integrated gasification combined cycle (BIGCC) power generation system using Aspen Plus: Performance analysis and energetic assessment

A new biomass integrated gasification combined cycle (BIGCC), which featured an innovative two-stage enriched air gasification system coupling a fluidized bed with a swirl-melting furnace, was proposed and built for clean and efficient biomass utilization. The performance of biomass gasification and power generation under various operating conditions was assessed using a comprehensive Aspen Plus model for system optimization. The model was validated by pilot-scale experimental data and gas turbine regulations, showing good agreement. Parameters including oxygen percentage of enriched air (OP), gasification temperature, excess air ratio and compressor pressure ratio were studied for BIGCC optimization. Results showed that increase OP could effectively improve syngas quality and two-stage gasification efficiency, enhancing the gas turbine inlet and outlet temperature. The maximum BIGCC fuel utilization efficiency could be obtained at OP of 40%. Increasing gasification temperature showed a negative effect on the two-stage gasification performance. For efficient BIGCC operation, the excess air ratio should be below 3.5 to maintain a designed gas turbine inlet temperature. Modest increase of compressor pressure ratio favored the power generation. Finally, the BIGCC energy analysis further proved the rationality of system design and sufficient utilization of biomass energy.

A novel adaptive generic model control strategy for internal thermally coupled air separation columns with multivariable recursive estimation

A gasification process is key in clean electricity production and decarbonization in an integrated gasification combined cycle (IGCC) plant. The quality of the gasification process depends on the stability of the product-concentration streamed from the internal thermally coupled air separation column (ITCASC) unit. There is a need for a stable product-concentration supply to sustain clean electricity production. A proportional-integral-derivative control (PID) control and a nonlinear internal model control (NIMC) scheme are first explored to control the IGCC-ITCASC. Moreover, a robust generic model control (RGMC) is employed to deal with the IGCC-ITCASC inherent nonlinearity and strong interaction that make it very difficult to control. To obtain a satisfactory control performance, an adaptive generic model control (AGMC) with a multivariable recursive estimation is developed. The compared control systems show that AGMC can better handle both the system nonlinearity and strong interaction while improving the control performance.

Effect of coal particle size on gasification performance of two‐stage entrained‐flow coal gasifier

AbstractTo clarify the effect of coal particle sizes on gasification performance of an advanced two‐stage entrained‐flow coal gasifier for IGCC (integrated gasification combined cycle) application, a comprehensive three‐dimensional numerical model is established by incorporating the shrinking core model combined with the Langmuir‐Hinshelwood kinetic rate expression, which considers the inhibitory effect of CO on char‐CO2 reaction. The flow, temperature, and species distributions were obtained, and the results are consistent with the operating data. Results show that the helical flow and eight recirculation zones in the gasifier improve carbon conversion efficiency through extending the residence time of coal particles. Slow devolatilization of large particles caused by slow heating retards volatiles combustion, and thus char combustion and gasification. As a result, less char gasification and higher gas temperature appear in the injection region of the first stage. Higher inertia of larger particles produces higher slip velocity, which enhances heat transfer and mass diffusion to char particles and increases char consumption rate in diffusion‐limited regions. The regions of high inner wall temperature spread from locations around burners to the whole inner wall of the injection and bottom regions in the first stage with increase of coal particle sizes.

Design and Modeling of a Carbon Capturing Membrane for Integrated Gasification Combined Cycle Power Plant

The main idea of this research paper is to provide an innovative way of capturing carbon dioxide emissions from a coal powered power plant. This research paper discusses the design and modeling of a carbon capturing membrane which is being used in an IGCC power plant to capture carbon dioxide from its exhaust gases. The modeling and design of the membrane is done using CFD software namely Ansys workbench. The design and modeling is done using two simulations, one describes the design and structure and the second one demonstrates the working mechanism of the membrane. This paper also briefly discusses IGCC which is environmentally benign compared to traditional pulverized coal-fired power plants, and economically feasible compared to the Natural Gas Combine Cycle (NGCC). IGCC power plant is more diverse and offers flexibility in fuel utility. This paper also incorporates a PFD of integrated gasification power plant with the carbon capturing membrane unit integrated in it. Index Terms: Integrated gasification combined cycle power plant, Carbon capture and storage, Gas permeating membrane, CFD based design of gas permeating membrane.

Simulation of a moving bed chemical looping system for electricity production from coal via chemical looping water splitting

AbstractCoal is a crucial energy source for modern industry and society. Because coal is one of the most CO2‐intensive carbonaceous fuels, the combustion of coal with CO2 capture is of great environmental relevance. However, the conventional coal‐based power generation processes, including the pulverized coal (PC) boiler process and the integrated gasification combined cycle (IGCC) process, suffer a significant efficiency loss when integrated with conventional CO2 capture methods. Chemical looping technology is a promising alternative pathway for coal‐based power generation with intrinsic CO2 separation and capture. Process simulation of chemical looping processes can provide an overview on the viability of the processes, thereby quantifying their advantages over conventional processes. This study presents the process simulation of a chemical looping water splitting combined cycle (CLWS‐CC) system for electricity generation. The CLWS‐CC process directly uses coal as the feedstock to produce H2, which is subsequently combusted in a combined cycle to generate electricity. The oxygen carriers used in the chemical looping process are optimized in their composition. Autothermal operation is established within the chemical looping system. Four CLWS‐CC cases that operate at different pressures are considered. In two of the four cases, an unequal pressure operating strategy is adopted to minimize the compression power consumption in order to enhance the overall process energy efficiency. The process simulation shows that the CLWS‐CC process is able to achieve an 18% increase in net plant efficiency over the conventional IGCC process.