Conventional Integrated Gasification Combined Cycle Research Articles

Zero/negative carbon emission coal and biomass staged co-gasification power generation system via biomass heating

Currently, most coal utilization technologies cannot completely remove CO2, which hinders coal utilization in the context of carbon neutrality. Staged coal-steam gasification has proven to be a potential clean coal utilization method suitable for power generation. However, it cannot achieve zero or negative carbon emissions, and there is the potential to improve energy efficiency further. This study introduces biomass into staged coal gasification and proposes a novel power generation system based on coal- and biomass-staged co-gasification via biomass external combustion heating. Biomass with a lower energy level was combusted to provide heat for gasification, thus improving the energy level matching between the gasification and biomass combustion reactions. The synergistic effect of coal and biomass reduces the tar yield and improves the gasification efficiency. Furthermore, as a carbon-neutral fuel, the introduction of biomass in the staged coal-gasification process can achieve zero or negative carbon utilization of coal. The entire system was simulated using the ASPEN PLUS software, key processes were experimentally validated, and the energy efficiency and carbon emission performance were systematically studied. The results indicated that the improved gasification methods and the synergistic effect between coal and biomass significantly improved the energy performance and emission reduction characteristics. The power efficiency of the novel system was the highest at 40.03% when the biomass blending ratio of the co-gasification sub-process was 0.8, which was 5.27% and 10.46% higher than conventional integrated gasification combined cycle (IGCC) system and biomass direct-fired power plant. The carbon-specific emissions of the novel system could be reduced to −308.1 kgCO2/MWh, achieving negative carbon utilization of fossil fuels. This novel staged coal and biomass co-gasification method heating by biomass can achieve efficient and negative carbon utilization of fossil fuels.

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.

The oxygen production pre-combustion (OPPC) IGCC plant for efficient power production with CO2 capture

This work presents a novel integrated gasification combined cycle (IGCC) power plant configuration for CO2 capture with minimal energy penalty. The proposed oxygen production pre-combustion (OPPC) power plant synergistically integrates a gas switching oxygen production (GSOP) unit into a pre-combustion IGCC power plant, reducing the energy penalty through two channels: 1) avoidance of a cryogenic air separation unit and 2) pre-heating the air sent to the combined power cycle, which reduces the steam requirement for shifting CO to H2 and the CO2 capture duty involved in pre-combustion CO2 capture. Relative to a conventional pre-combustion IGCC benchmark, the OPPC configuration improves the electric efficiency by about 6%-points, although the CO2 capture ratio reduces by about 6%-points. OPPC as avoids the maximum temperature limitation of Chemical Looping Combustion based plants, and can therefore benefit from efficient modern gas turbine technology operating at very high inlet temperatures. CO2 removal via physical absorption (Selexol) generally results in higher efficiencies, but lower CO2 avoidance than chemical absorption (MDEA). Plant efficiency also benefits from an increase in GSOP operating temperature, although the maximum temperature was limited to 900 °C to avoid any temperature-related challenges with oxygen carrier stability or downstream valves and filters. OPPC therefore appears to be a promising configuration for minimizing the energy penalty of CO2 capture in IGCC power plants, combining well known and proven technology blocks with a GSOP reactor cluster instead of an ASU.

Improvement of integrated gasification combined cycle performance using nitrogen from the air separation unit as turbine coolant

An integrated gasification combined cycle (IGCC) power plant uses fuel made by coal gasification for gas turbines. The oxygen required for the gasification reaction is supplied using a cryogenic air separation unit (ASU), and a large amount of nitrogen is generated. In the conventional IGCC, nitrogen generated in the ASU is injected into the combustor to generate more power. However, since the temperature of the injected nitrogen is lower than that of the air supplied to the combustor, injecting nitrogen requires more fuel to maintain a constant outlet temperature (i.e., turbine inlet temperature (TIT)). We propose a novel system configuration to improve the performance of the IGCC and analyzed its effects. We used nitrogen generated in the ASU as a turbine blade coolant instead of compressed air. Since the nitrogen temperature was lower than the temperature of compressed air, the turbine blades can be protected with a lower flow rate of coolant. As a result, both the power and efficiency are increased. We also investigated possibilities for further performance improvement by changing design parameters and determined the design point that maximizes the efficiency.

Economic assessment of chemical looping oxygen production and chemical looping combustion in integrated gasification combined cycles

Chemical looping promises significant reductions in the cost of CO2 capture and storage (CCS) by enabling energy conversion with inherent separation of CO2 at almost no energy penalty. This study evaluates the economic performance of a novel power plant configuration based on the principle of packed bed chemical looping. The new configuration, called COMPOSITE, integrates packed bed chemical looping combustion (PBCLC) and chemical looping oxygen production (CLOP) into an integrated gasification combined cycle (IGCC) power plant. The CLOP unit achieves air separation with minimal energy penalty and the PBCLC unit achieves fuel combustion with inherent CO2 capture. The COMPOSITE configuration achieved a competitive CO2 avoidance cost (CAC) of €45.8/ton relative to conventional IGCC with pre-combustion CO2 capture with €58.4/ton. However, the improvement was minimal relative to a simpler configuration using an air separation unit (ASU) instead of the CLOP reactors, returning a CAC of €47.3/ton. The inclusion of hot gas clean-up further improved the CAC of the COMPOSITE configuration to €37.8/ton. Optimistic technology assumptions in the form of lower contingency costs and better CLOP reactor performance reduced the CAC to only €24.9/ton. Further analysis showed that these highly efficient chemical looping plants will be competitive with other low-carbon power plants (nuclear, wind and solar) in a technology-neutral climate policy framework consistent with a 2 °C global temperature rise. Economic attractiveness improves further in a high CO2 tax scenario where large-scale deployment of CO2 negative bio-CCS plants is required.

Energy and exergy analysis of chemical looping combustion technology and comparison with pre-combustion and oxy-fuel combustion technologies for CO2 capture

Carbon dioxide (CO2) emitted from conventional coal-based power plants is a growing concern for the environment. Chemical looping combustion (CLC), pre-combustion and oxy-fuel combustion are promising CO2 capture technologies which allow clean electricity generation from coal in an integrated gasification combined cycle (IGCC) power plant. This work compares the characteristics of the above three capture technologies to those of a conventional IGCC plant without CO2 capture. CLC technology is also investigated for two different process configurations—(i) an integrated gasification combined cycle coupled with chemical looping combustion (IGCC–CLC), and (ii) coal direct chemical looping combustion (CDCLC)—using exergy analysis to exploit the complete potential of CLC. Power output, net electrical efficiency and CO2 capture efficiency are the key parameters investigated for the assessment. Flowsheet models of five different types of IGCC power plants, (four with and one without CO2 capture), were developed in the Aspen plus simulation package. The results indicate that with respect to conventional IGCC power plant, IGCC–CLC exhibited an energy penalty of 4.5%, compared with 7.1% and 9.1% for pre-combustion and oxy-fuel combustion technologies, respectively. IGCC–CLC and oxy-fuel combustion technologies achieved an overall CO2 capture rate of ∼100% whereas pre-combustion technology could capture ∼94.8%. Modification of IGCC–CLC into CDCLC tends to increase the net electrical efficiency by 4.7% while maintaining 100% CO2 capture rate. A detailed exergy analysis performed on the two CLC process configurations (IGCC–CLC and CDCLC) and conventional IGCC process demonstrates that CLC technology can be thermodynamically as efficient as a conventional IGCC process.

Study on a new IGCC (Integrated Gasification Combined Cycle) system with CO2 capture by integrating MCFC (Molten Carbonate Fuel Cell)

In this paper, a new Integrated Gasification Combined Cycle (IGCC) system with less CO2 emission by integrating a Molten Carbonate Fuel Cell (MCFC) to capture CO2 has been proposed. The performance of the new system is compared with other three systems: a conventional IGCC system without CO2 capture, an IGCC system with pre-combustion capture and an IGCC system with oxy-fuel combustion capture. In addition, the effects of the key parameters of MCFC such as CO2 utilization factor, fuel utilization factor and the operating temperature of MCFC on the new system performance have been analyzed and compared. The results show that when the CO2 capture rate is 88%, the efficiency of the new system is about 47.31%, 2.97% higher than that of the IGCC without CO2 capture, 10.45% higher than the IGCC system with pre-combustion CO2 capture, and 12.55% higher than the IGCC system with oxy-fuel combustion CO2 capture. Though the new system has an obvious superiority of thermal performance, its technical economic performance needs be improved with the technical development of MCFC. The research achievements will provide a new way for further study on CO2 capture from IGCC system with lower energy penalty.

Proposed combined-cycle power system based on oxygen-blown coal partial gasification

A combined-cycle power system based on oxygen-blown coal partial gasification is proposed to promote the performance and reduce the investment of conventional integrated gasification combined cycle (IGCC) power system. The proposed power system combines the characteristics of IGCC and pressurized fluidized-bed cycle power systems, and its performance is analyzed. The thermal efficiency of the proposed power system is about 3% higher than that of the reference system. Exergy analysis is also performed to reveal the internal phenomenon of the energy conversion. It is found that the main character of the proposed power system is the reduction of exergy destruction during chemical energy conversion processes, i.e., the gasification process and the syngas combustion process. Such a result implies the proposed power system can realize better utilization of the coal chemical energy. Some other configurations of the proposed power system are also considered for varying the work conditions or for further adaptation to state-of-the-art technology. The primary investment cost of the proposed power system is also reduced due to the decrease in the gasification temperature and the carbon conversion ratio.

Analysis of Hydroxide Sorbents for CO2 Capture from Warm Syngas

Integrated gasification combined cycle (IGCC) with CO2 capture and sequestration (CCS) is a promising technology to efficiently mitigate the emission of CO2. Warm CO2 removal has been predicted to make the CO2 capture process more efficient. Here, we investigate the efficiency penalties associated with CO2 removal via a pressure swing adsorption (PSA) process using metal hydroxide sorbents at elevated temperature. We use numerical models constructed in MATLAB and integrate these with Aspen Plus process simulations. We apply these models to both general metal hydroxides of variable enthalpy of adsorption and real metal hydroxides identified using density functional theory (DFT) calculations. We show that having an enthalpy of adsorption between 15 and 20 kJ/mol results in a PSA process that gives an overall IGCC–CCS efficiency that is competitive with the conventional IGCC–CCS process using (cold) Selexol. An enthalpy of adsorption of 20 kJ/mol is predicted to be the most favorable because it yielded a pro...

Integrated assessment of IGCC power generation technology with carbon capture and storage (CCS)

IGCC (Integrated Gasification Combined Cycle) is a power generation technology in which the solid feedstock is partially oxidized with oxygen and steam to produce syngas. In a conventional IGCC design without carbon capture, the syngas is purified for dust and hydrogen sulphide removal and then it is sent to a CCGT (Combined Cycle Gas Turbine) for power generation. CCS (Carbon capture and storage) technologies are expected to play a significant role in the coming decades for reducing the greenhouse gas emissions. IGCC is one of the power generation technologies having the highest potential to capture CO2 with low penalties in term of plant energy efficiency, capital and operational costs.This paper investigates the most important techno-economic and environmental indicators (e.g. power output, ancillary consumption, energy efficiency, CW consumption, normalised mass and energy balances and plant construction materials, capital and O&M (operational & maintenance) costs, specific CO2 emissions, cost of electricity, CO2 removal and avoidance costs etc.) for IGCC with CCS. Coal-based IGCC cases produce around 400–450 MW net electricity with 90% carbon capture rate. Similar IGCC plants without CCS were presented as references. Future IGCC developments for energy vectors poly-generation were also presented.

Incorporating IGCC and CaO sorption-enhanced process for power generation with CO2 capture

Integrated gasification combined cycle (IGCC) is a power generation technology to convert solid fuels into electricity. IGCC with CCS is regarded as a promising option to mitigate CO2 emission. In this paper, the CaO sorption-enhanced process is incorporated downstream with coal gasification to produce a hydrogen-rich stream for electricity production and CO2 separation. A WGS-absorber substitutes the high- and low-temperature water–gas shift reactors and desulfurization units in conventional IGCC–CCS to produce a hydrogen-rich stream, which is sent onto a gas turbine. CaO is used as the sorbent to enhance hydrogen production and for CO2 capture. Regeneration of CaO is completed via calcination in a regenerator vessel. The IGCC with CaO sorption-enhanced process is modeled and simulated using Aspen Plus software. Two commercial available gasification technologies, Shell and Texaco, are integrated with the sorption-enhanced process. The results showed IGCC with CaO sorption-enhanced process has a satisfactory system performance. Even though the net electricity efficiency is not as high as expected, just around 30–33%, the system has a high CO2 capture efficiency ∼97% and low pollutant emissions. Moreover, compared with conventional IGCC–CCS, the schematic diagram of the IGCC–CCS process is simplified. Parameters that affect the plant performance are analyzed in the sensitive analysis, including WGS-absorber temperature, H2O/CO ratio, pressure, etc. Some challenges to the system are also discussed.

Technical evaluations of carbon capture options for power generation from coal and biomass based on integrated gasification combined cycle scheme

Abstract Integrated Gasification Combined Cycle (IGCC) is a technology for power generation in which the feedstock is partially oxidized with oxygen and steam to produce syngas. In a conventional IGCC design without carbon capture, the syngas is purified for dust and hydrogen sulphide removal and then sent to a Combined Cycle Gas Turbine (CCGT) for power production. The hot GT flue gases are sent to Heat Recovery Steam Generator (HRSG) for steam generation. Additional power is produces by expanding the steam generated in a steam turbine. Carbon capture and storage (CCS) technologies are expected to play a significant role in the coming decades for reducing the greenhouse gas emissions. Integrated Gasification Combined Cycle is one of the power generation technologies having the highest potential to capture carbon dioxide with the low penalties in term of plant energy efficiency and cost. The modification of the IGCC design for carbon capture can be done in various plant concepts considering the carbon capture method to be used (e.g. pre- and post-combustion capture, syngas chemical looping etc.). This paper investigates various carbon capture methods suitable to be applied for an IGCC plant for power generation. The coal blended with biomass (sawdust) based IGCC case study investigated in the paper produces around 400–500 MW net electricity with more than 90% carbon capture rate. An important focus of the paper is concentrated on overall energy efficiency optimization of the IGCC plant concepts with various carbon capture options by better heat and power integration of the main plant sub-systems (e.g. steam integration between gasification island, syngas conditioning line and the steam cycle, influence of heat and power demand for Acid Gas Removal unit etc.). A particular attention of the paper is focused on the quality specification for the captured carbon dioxide stream considering various capture options but also the storage options (enhanced oil recovery, storage in depleted oil and gas fields, saline aquifers etc.).

Evaluation of energy integration aspects for IGCC-based hydrogen and electricity co-production with carbon capture and storage

Integrated Gasification Combined Cycle (IGCC) is a power generation technology in which the solid feedstock is partially oxidized with oxygen and steam to produce syngas. In a conventional IGCC design without carbon capture, the syngas is purified for dust and hydrogen sulphide removal and then sent to a Combined Cycle Gas Turbine (CCGT) for power generation. Carbon capture technologies are expected to play an important role in the coming decades for reducing the greenhouse gas emissions. In a modified IGCC design for carbon capture, the syngas is catalytically shifted to maximize the hydrogen level and to concentrate the carbon species in the form of carbon dioxide which can be later captured in a pre-combustion arrangement. After carbon dioxide capture, the hydrogen-rich syngas can be either purified in a Pressure Swing Adsorption (PSA) unit and exported to the external customers (e.g., chemical industry, PEM fuel cells) or used in a CCGT for power generation. This paper investigates the most important energy and process integration issues for hydrogen and electricity co-production scheme based on coal gasification process with carbon capture and storage (CCS). The evaluated coal-based IGCC case produces around 400 MW net electricity and has a flexible hydrogen output in the range of 0–200 MW (LHV) with a 90% carbon capture rate. The principal focus of the paper is on the evaluation of energy integration aspects so as to maximize the overall plant energy efficiency. Optimization includes heat and power integration of the main plant sub-systems (e.g., integration of steam generated in gasification island, with the requirements for syngas treatment, power generation in the combined cycle, best use of PSA tail gas in the power block, heat and power demand for acid gas removal unit, integration of air separation unit and gas turbine compressor etc.), sensitivity analysis (e.g., influence on ambient conditions).

Feasibility of the integration of a molten carbonate fuel-cell system and an integrated gasification combined cycle

IGCC (Integrated Gasification Combined Cycle) power plants look promising for the environmentally-friendly, large-scale production of electrical energy from low-cost fossil feedstocks such as coal or refinery residues. In IGCC plants hydrogen is an intermediate product, as a syngas component, between the thermochemical section and the power section, which is a conventional combined cycle modified to handle this low-density fuel. Replacing the conventional power section with a fuel cell, the IGFC (Integrated Gasification Fuel Cell) configuration promises lower emissions, higher efficiency and possibility to scale down to smaller sizes. To explore the challenges and the feasibility of such an integration we have proposed putting a pilot-scale fuel-cell system into operation within an existing, conventional IGCC, creating a hybrid fuel-cell-IGCC. Two innovative configurations have been proposed and optimised for a pilot-scale MCFC–GT (Molten Carbonate Fuel-Cell–Gas Turbine) system, based on a typical syngas for IGCC plants such as that in operation at ISAB Energy Srl. The system has been modelled using the LIBPF process simulation library.

Techno-economic evaluation of advanced IGCC lignite coal fuelled power plants with CO 2 capture

The techno-economic evaluation of four novel integrated gasification combined cycle (IGCC) power plants fuelled with low rank lignite coal with CO 2 capture facility has been investigated using ECLIPSE process simulator. The performance of the proposed plants was compared with two conventional IGCC plants with and without CO 2 capture. The proposed plants include an advanced CO 2 capturing process based on the Absorption Enhanced Reforming (AER) reaction and the regeneration of sorbent materials avoiding the need for sulphur removal component, shift reactor and/or a high temperature gas cleaning process. The results show that the proposed CO 2 capture plants efficiencies were 18.5–21% higher than the conventional IGCC CO 2 capture plant. For the proposed plants, the CO 2 capture efficiencies were found to be within 95.8–97%. The CO 2 capture efficiency for the conventional IGCC plant was 87.7%. The specific investment costs for the proposed plants were between 1207 and 1479 €/kW e and 1620 €/kW e and 1134 €/kW e for the conventional plants with and without CO 2 capture respectively. Overall the proposed IGCC plants are cleaner, more efficient and produce electricity at cheaper price than the conventional IGCC process.

System Study on Partial Gasification Combined Cycle With CO2 Recovery

A partial gasification combined cycle with CO2 recovery is proposed in this paper. Partial gasification adopts cascade conversion of the composition of coal. Active composition of coal is simply gasified, while inactive composition, that is char, is burnt in a boiler. Oxy-fuel combustion of syngas produces only CO2 and H2O, so the CO2 can be separated through cooling the working fluid. This decreases the amount of energy consumption to separate CO2 compared with conventional methods. The novel system integrates the above two key technologies by injecting steam from a steam turbine into the combustion chamber of a gas turbine to combine the Rankine cycle with the Brayton cycle. The thermal efficiency of this system will be higher based on the cascade utilization of energy level. Compared with the conventional integrated gasification combined cycle (IGCC), the compressor of the gas turbine, heat recovery steam generator (HRSG) and gasifier are substituted for a pump, reheater, and partial gasifier, so the system is simplified obviously. Furthermore, the novel system is investigated by means of energy-utilization diagram methodology and provides a simple analysis of their economic and environmental performance. As a result, the thermal efficiency of this system may be expected to be 45%, with CO2 recovery of 41.2%, which is 1.5–3.5% higher than that of an IGCC system. At the same time, the total investment cost of the new system is about 16% lower than that of an IGCC. The comparison between the partial gasification technology and the IGCC technology is based on the two representative cases to identify the specific feature of the proposed system. The promising results obtained here with higher thermal efficiency, lower cost, and less environmental impact provide an attractive option for clean-coal utilization technology.

Energy and capital cost analysis of CO 2 capture in coal IGCC processes via gas separation membranes

In this study, the use of a hybrid coal integrated gasification combined-cycle (IGCC) system, consisting of a gasifier, a shift reactor and a membrane separator, has been examined. Two alternative separation options were studied: (a) low temperature separation, using polymer membranes, and (b) high temperature separation, by ceramic membranes. Single and multistage separation was examined for operation at 16 and 23 bar. The energy and cost analysis of the alternative cases show that CO 2 removal in this hybrid IGCC scheme is technically feasible. Incorporation of shift reaction and membrane separators results in an energy penalty of 8–14% units, depending on pressure and staging, and in increased capital cost, especially for the ceramic membranes. However, this technology would permit reduction of CO 2 emissions exceeding 50%, compared to conventional IGCC.