IGCC System Research Articles

Optimization of parameters and thermodynamics of gasification process for enhanced CO2 capture in an IGCC system

The integrated gasification combined cycle (IGCC) technology is renowned for its high energy utilization efficiency. However, the exhaust emissions from an IGCC power plant still contain a significant amount of carbon dioxide (CO2), which has a detrimental impact on the environment. Therefore, it is necessary to capture CO2 and reduce its emissions in IGCC systems. This study develops an integrated model for the process simulation of a 250 MW IGCC system with an advanced CO2 capture technology. After establishing the model, sensitivity analysis is conducted to obtain the optimal parameters for methyldiethanolamine (MDEA) absorption. The operational parameters of the coal gasification unit are optimized to mitigate the elevated energy consumption. The results indicate that the original gasification system has an energy consumption rate of 57.6 %, whereas the optimized system achieves a significant reduction to 42.8 %, resulting in a notable improvement in the energy efficiency of the gasification unit by 10.2 %. The exergy efficiency of the gasification process is improved by 6.4 %. This research paradigm showcases the opportunity to significantly enhance the sustainability and economic feasibility of IGCC technology.

Advanced design, parameter optimization, and thermodynamic analysis of integrated air-blown IGCC power plants

With the increasing energy demand, it is essential to improve the utilization of traditional energy sources. Coal is still the mainstay of the Chinese energy market, especially in power generation. The IGCC offers significant advantages in terms of power efficiency and environmental protection. However, conventional IGCC uses oxygen as the gasification medium, posing serious economic challenges. To address this challenge, in this study, the overall system process for the IGCC systems using air-blown gasification is constructed by Aspen Plus. To explore the potential of the thermal performance of the air-blown gasification IGCC system, the operating parameters and process flows are improved. The energy and exergy analysis of the whole system using the advanced process is carried out and compared with the oxygen gasification IGCC. Optimal operating parameters and technical parameters are determined, and the gasifier is optimized. The results show that the system efficiency increased by 3.17%, and the exergy efficiency increased by 3.09%. Although the integrated gas turbine process does not offer obvious advantages, it is more compatible with the current gas turbine in terms of flow rate. The utilization of a high-pressure reheat gas turbine results in a 2.52% increase in system efficiency. The implementation of high-pressure reheat gas turbines and hot gas desulfurization can improve the thermal performance of the system. The air-blown gasification IGCC with this process has the highest power supply efficiency of 52.80%. It presents an improvement of 3.69% compared with oxygen gasification. The exergy loss in the cooling and cleaning module and the gas turbine module is significantly reduced. The heat efficiency of the air-blown gasification IGCC is 3.60% higher, and the effective energy in the system is fully utilized. It provides some heuristic ideas for the clean and efficient utilization of coal resources.

Process modelling and optimization of a 250 MW IGCC system: Model setup, validation, and preliminary predictions

Process modelling and optimization of a 250 MW IGCC system: Model setup, validation, and preliminary predictions

Polycyclic aromatic hydrocarbons (PAHs) and soot formations under different gasifying agents: Detailed chemical kinetic analysis of a two-stage entrained flow coal gasifier

The injection of CO2 with coal into coal gasifier is a promising approach to achieve CO2 recirculation. Predicting the formation and evolution of polycyclic aromatic hydrocarbons (PAHs) and soot during coal gasification is particularly important as their presence poses challenges to the gasifier operation and environment. However, the effect of CO2 injection on their formation must be elucidated in more detail to optimize the gasifier design. This work investigates PAHs and soot formations in gas-phase reactions under different gasifying agents (Air, O2/CO2, O2/H2O) in a two-stage entrained flow coal gasifier using a detailed chemical kinetic model (DCKM). Under the O2/CO2– and O2/H2O-blown conditions, aromatics reforming was progressed whereas the yields of tar and soot were effectively suppressed. The benzene was observed as the most abundant PAHs species, followed by naphthalene and acenaphthalene. Regarding the relative oxygen concentration, the conversion behavior of aromatics was significantly influenced in the O2/CO2-blown condition, while the somewhat effect was found in the O2/H2O-blown condition. Tar yield peaked at 50% relative oxygen concentration in the O2/CO2-blown condition. The present finding may have practical significance in the O2/CO2-blown gasifier to facilitate CO2 recirculation for the oxy-fuel IGCC system.

Study on the bistable vibration behaviour of a rod-fastened rotor-bearing system.

Gas turbine generator sets are widely used in IGCC system, gas-steam combine cycle, distributed energy system et al. for its advantages of low pollution, high efficiency, quick start and stop. The structure of gas turbine rotor can be divided into integral rotor and rod-fastened rotor. Experimental study shows that the vibration signal, especially the displacement signal, of the rod-fastened rotor will increase/decrease greatly in a small interval of rotating speed. The reason for this phenomenon is the unique structure of the rod-fastened rotor, namely the interfaces between discs. In this paper, based on the Lagrange equation, the equation of motion of a rod-fastened rotor-bearing system considering the damping of the contact interface is established. The bistable behaviour and hysteretic cycle, also called the jumping phenomenon in engineering, are revealed. In addition, a test bench of the rod-fastened rotor-bearing system is built. The bistable behaviour and hysteretic cycle are experimentally proven, and the effect of the eccentric distance of the rotor on the bistable behaviour is experimentally explored.

Thermodynamic analysis of 350 MWe coal power plant based on calcium looping gasification with combined cycle

Carbon capture and sequestration (CCS) technology is needed for fossil fuels (FFs) based power generation, in order to make it sustainable in future. Calcium looping gasification (CLG) is a novel energy technology that fulfils CCS, unlike IGCC post combustion, CO2 capture is not required, making it less energy demanding and saving capital cost, moreover CaO-CaCO3 is an exothermic reaction, hence the generated heat is adequate to perform CLG. In this study, both experiments and simulations of CLGCC, with CaO as a CO2 sorbent, were performed at varying gasifier temperatures and pressures using Aspen Plus, while results were compared to maximize the overall efficiency. Here, we propose calcium looping gasification with combined cycle (CLGCC) simulation using Aspen Plus with CaO as CO2 sorbent, and results are validated against experimental data in terms of gasifier temperature and pressure. The IGCC without CCS system along with CLGCC are simulated simultaneously for comparison. The CLGCC system achieved an efficiency as high as 54.93%, while IGCC's system without CCS efficiency was calculated as 53.22% and corresponding exergetic efficiencies are 51.67% and 50.03%, respectively. The carbon capture efficiency of CLGCC is 83.5 % with 94.4 vol% of CO2 achieved after steam condensation for carbon capture system. On the basis of results, we demonstrate the applicability of CLGCC against the conventional power plants and it has a great window for adaptation in the future in advanced power plants.

Update of project to develop high-efficiency oxy-fuel IGCC system

Update of project to develop high-efficiency oxy-fuel IGCC system

On a novel carbon-negative IGCC system with cascade CO2 combined cycle

A novel carbon-negative integrated gasification combined cycle (NIGCC) is proposed. The chemical looping air separation technology, the supercritical CO2 Brayton cycle and an improved transcritical CO2 Rankine cycle are employed for efficient bio-power generation. The NIGCC system is then systematically modeled, with all the subunit models elaborated and validated against the reported data in literature. Thereafter, the effects of different key operation parameters on the system essential performance indicators are studied in terms of thermodynamics and economics. The exergy analyses for the NIGCC system are also implemented and the corresponding exergy Grassmann diagram are drawn. The net electric efficiency, CO2 emission rate and the levelized cost of electricity of the NIGCC system can reach 51%, −0.6 kg/kWh and 0.63$/kWh, respectively. The exergy efficiencies of the gasifier and gas turbine can be potentially improved so that the NIGCC performance can be further promoted.

Waste tyre to electricity: Thermodynamics analysis

Waste tyre generation in South Africa is an issue for which no sustainable solution has been found. South Africa generates over 177 385 tons of waste tyres per year, and only around 25 % is recycled, the remaining 75 % accumulates in storage depots, and landfills across the country. In this work, a slurry fed IGCC system is analysed. This system does not require the use of oxygen during gasification and is designed to be self-sustaining and produces electrical power. A sensitivity analysis shows that considerable gains in thermal efficiency are made by using a turbine pressure ratio of between 20 and 30 bar. This data was then used to develop a system that processes 518 ton/day of waste tyres and operates at a gas turbine pressure ratio of 30 bar and a 1600 °C combustion temperature. The net power production from the system is 89 MW, with a thermal efficiency of 45.65 % and work efficiency of 44.97 %. However, the results from Aspen Plus were significantly less than the predicted with an overall net efficiency of 32 %. Despite the discrepancy waste tyre IGCC net-work output was found to be 10.5 GJ/ton of tyre much higher than that of conventional coal IGCC at 9.6 GJ/ton of coal.

1-2-3 二段噴流床ガス化炉における水蒸気ガス化反応の促進によるIGCCシステムの効率向上効果の評価

1-2-3 二段噴流床ガス化炉における水蒸気ガス化反応の促進によるIGCCシステムの効率向上効果の評価

Techno-economic analysis of methanol and electricity poly-generation system based on coal partial gasification

The methanol and electricity poly-generation system based on coal partial gasification is proposed. Techno-economic analysis of the system is conducted by using Aspen Plus and the effects of methanol synthesis temperature and cyclic gas reflux ratio on the system performance are studied. The detailed economic data are obtained. The IGCC system is established simultaneously and compared with the poly-generation system. The results show that both methanol production and system efficiency decrease with the increase of methanol synthesis temperature. Methanol production increases while system efficiency decreases with increase of the recycle gas ratio. System efficiency would reach as high as 56.8%, while the system efficiency of IGCC is 53.11%. By the calculation of the economic data, the IRR and the payback period of the poly-generation system are 24.1% and 4.14 years, respectively. While IRR and payback period of IGCC system are 3.4% and 18.06 years, respectively. The results show that methanol and electricity poly-generation system based on coal partial gasification has a promising prospect.

Update of Project to Develop High-Efficiency Oxy-Fuel IGCC System

Update of Project to Develop High-Efficiency Oxy-Fuel IGCC System

Process simulation and integration of IGCC systems for H2/syngas/electricity generation with control on CO2 emissions

IGCC is a pre-combustion technology that can be effectively used to produce both hydrogen and electricity while reducing the greenhouse gas (GHG) emissions. Two process models are developed in Aspen Plus® software and are compared techno-economically. The conventional design of IGCC process is taken as case 1, whereas, case 2 represents the conceptual design of sequential integration of reforming model with the gasification unit to enhance the syngas yield. The case 2 utilizes the steam generated in the gasification process to sustain the methane reforming process which consequently enhances both the H2 production capacity and cold gas efficiency. It has been analyzed from results that case 2 can enhance the process performance by 4.77% and economics in terms of cost of electricity by 5.9% compared to the conventional process. However, the utilization of natural gas in the case 2 is considered as a standalone fuel so the process performance of NGCC power plants has been also incorporated to ensure the realistic analysis. The results also showed that case 2 design offers 3.9% higher process performance than the cumulative (IGCC + NGCC) processes, respectively. Moreover, the CO2 specific emissions and LCOE for the case 2 is also lower than the case.

Verification of applicability to wide range coal property of O<sub>2</sub>/CO<sub>2</sub> –blown gasification technology for Oxy-fuel IGCC system

Verification of applicability to wide range coal property of O<sub>2</sub>/CO<sub>2</sub> –blown gasification technology for Oxy-fuel IGCC system

Verification of O<sub>2</sub>/CO<sub>2</sub> –blown gasification technology for oxy-fuel IGCC system

Verification of O<sub>2</sub>/CO<sub>2</sub> –blown gasification technology for oxy-fuel IGCC system

Technical-economical Analysis on Co-gasification of Coal and Biomass Based on the IGCC System with a Two-staged Gasifier

In this paper, a two-staged entrained-flow bed gasifier is proposed for the co-gasification of coal and biomass. The effect of biomass blending ratio on the two-staged co-gasification characteristics and the influence of fuel price, loan ratio, biomass blending and electricity price on the technical and economic efficiency of the IGCC system are considered. The results indicated that the content of H2 in syngas increased firstly and then decreased with the addition of biomass, which reached the maximum value of 30.87 % at 10 % biomass ratio. The content of CO increased with the raising of biomass ratio, and the growth rate reached the maximum at 10 % biomass ratio. The carbon conversion (CC) firstly raised and then decreased with the increase of the biomass ratio at the second stage. The cold gas efficiency (CGE) increased nearly 10 % when the biomass ratio increased from 0 to 10%. The CGE of two-stage co-gasification was above 85%, indicating two-staged co-gasification of coal and biomass can significantly improve the efficiency of cold gas. The technical-economical analysis on the IGCC system indicated that the loan rate had a significant influence on the system dynamic investment, internal rate of return and net present value. With the increasing of loan rate, the total dynamic investment based the benchmark interest rate of 6.15 increased from 413.67 million to 431.58 million under the maximum lending rate of 8.61%. When the lending rate was larger than 8.15%, the internal rate of return (IRR) was slightly higher than the benchmark rate of return in the power sector. The further increase of the loan interest rate would result in a reduction of the internal rate of return and a negative net present value.The internal rate of return, the cost ratio, and the net present value decreased with the increase in the fuel price. When the price ceiling of coal and biomass was 600 RMB·t-1 and 450 RMB·t-1, the IGCC system was economically viable. The influence of biomass blending ratio on technical, economic indicators was nonlinear. When the biomass ratio increased from 0 to 50%, the IRR, income ratio and net present value of the project increased firstly and then decreased. The effect of the grid price on the technical economic indicators was opposite to that of the fuel price. This paper provides a useful guide for optimization of the co-gasification process.

SENSITIVITY ANALYSIS OF COAL GASIFICATION IN TWO-STAGE ENTRAINED-FLOW GASIFIER: SYNGAS AND CARBON CONVERSION PREDICTION

The energy production from coal-fired power plant is increasing day by day, which result in increased CO 2 emission from the existing power plant. However, CO 2 emission from coal gasification can be reduced if an efficient CO 2 /O 2 /N 2 coal gasification is implemented in IGCC system. Numerical simulations of coal gasification under CO 2 /O 2 /N 2 gasification condition are carried out with the aim of describing the effects of model parameters, char reaction rates, operating conditions and heat losses to increase the syngas heating value and carbon conversion in a two stage entrained flow coal gasification process. The Eulerian–Lagrangian approach is applied to solve the Navier–Stokes equation and the particle dynamics. Finite rate/eddy dissipation model is used to calculate the rate of nine homogeneous gas-to-gas phase reactions. While only finite rate is used for the heterogeneous solid-to-gas phase reactions. It is found that the carbon conversions of combustor coal lie in the ranges from 97 wt% to 99 wt% for most of the calculated conditions. On the other hand, the carbon conversion of reductor coals varies from 45 wt% to 57 wt%. A noticeable change is obtained when the gasification occurs under a high-temperature condition. Remarkable outlet results of about 32 wt% CO, 0.58 wt% H 2 and 89 wt% overall carbon conversion are predicted if a high temperature of 1673K is maintained in the reductor. On the other hand, a reduced soot concentration is predicted if the O 2 concentration and/or the reductor gas temperature increase(s) in the gasifier.

A power generation system with integrated supercritical water gasification of coal and CO2 capture

Abstract Supercritical water gasification (SCWG) is a promising clean coal technology. A new power generation system with integrated supercritical water gasification of coal andCO2 capture is proposed in this article. The gasification product consisted of H2, CO, CO2, CH4, and unreacted supercritical water is directly combusted with pure O2to provide heat for other units of the system, and the combustion product is used for power generation in turbines. The combustion product consists only of CO2 and H2O. Thus, the CO2 can be easily captured under atmospheric condition. The thermal efficiency of the system can reach 38.31%, while the CO2 capture rate is 100%. The energy and exergic balances are conducted. The exergy efficiency of the system is 38.56%. The system has advantages over most coal-fired power plants with oxy-combustion or post-combustion technologies and IGCC systems with pre-combustion technologies.

Development of High-efficiency Oxy-fuel IGCC System

As reported in GHGT-12, CRIEPI engaged in NEDO project to develop CO2 capture IGCC system, whose efficiency is more than 42%(HHV), as joint project with Kyushu University since 2008. In this system, exhaust gas is recirculated to gasifier and gas turbine combustor, just as oxy-fuel combustion boiler. In 2015, CRIEPI started 2nd phase 5 years’ NEDO project with assistance of Mitsubishi Heavy industries and Mitsubishi Hitachi Power Systems. In this phase, MHI uses 50TPD gasifier and 1/3 scaled GT combustion test stand to obtain data to design large scale plant. On the other hand, CRIEPI modify its 3TPD gasifier to clarify O2/CO2 gasification performance. In addition, hot gas clean-up system will be examined in above 2 gasifiers. CRIEPI install exhaust gas recirculation unit to clarify fundamental characteristics of semi-closed cycle gas turbine. This paper is to show the progress after GHGT-12 and whole picture of 2nd phase project by CRIEPI.

Dry syngas purification process for coal gas produced in oxy-fuel type integrated gasification combined cycle power generation with carbon dioxide capturing feature

Electricity production from coal fuel with minimizing efficiency penalty for the carbon dioxide abatement will bring us sustainable and compatible energy utilization. One of the promising options is oxy-fuel type Integrated Gasification Combined Cycle (oxy-fuel IGCC) power generation that is estimated to achieve thermal efficiency of 44% at lower heating value (LHV) base and provide compressed carbon dioxide (CO2) with concentration of 93 vol%. The proper operation of the plant is established by introducing dry syngas cleaning processes to control halide and sulfur compounds satisfying tolerate contaminants level of gas turbine. To realize the dry process, the bench scale test facility was planned to demonstrate the first-ever halide and sulfur removal with fixed bed reactor using actual syngas from O2–CO2 blown gasifier for the oxy-fuel IGCC power generation. Design parameter for the test facility was required for the candidate sorbents for halide removal and sulfur removal. Breakthrough test was performed on two kinds of halide sorbents at accelerated condition and on honeycomb desulfurization sorbent at varied space velocity condition. The results for the both sorbents for halide and sulfur exhibited sufficient removal within the satisfactory short depth of sorbent bed, as well as superior bed conversion of the impurity removal reaction. These performance evaluation of the candidate sorbents of halide and sulfur removal provided rational and affordable design parameters for the bench scale test facility to demonstrate the dry syngas cleaning process for oxy-fuel IGCC system as the scaled up step of process development.