scholarly journals The Effect of CO2 Partial Pressure on CH4 Recovery in CH4-CO2 Swap with Simulated IGCC Syngas

Energies ◽  
2020 ◽  
Vol 13 (5) ◽  
pp. 1017
Author(s):  
Ya-Long Ding ◽  
Hua-Qin Wang ◽  
Chun-Gang Xu ◽  
Xiao-Sen Li

To investigate the influence of CO2 partial pressure on efficiency of CH4-CO2 swap from natural gas hydrates (NGHs), the replacement of CH4 from natural gas hydrate (NGH) is carried out with simulated Integrated Gasification Combined Cycle (IGCC) syngas under different pressures, and the gas chromatography (GC), in-situ Raman, and powder X-ray diffraction (PXRD) are employed to analyze the hydrate compositions and hydrate structures. The results show that with the P-T (pressure and temperature) condition shifting from that above the hydrate equilibrium curve of IGCC syngas to that below the hydrate equilibrium curve of IGCC syngas, the rate of CH4 recovery drastically rises from 32% to 71%. The presence of water can be clearly observed when P-T condition is above the hydrate equilibrium curve of IGCC syngas; however the presence of water only occurs at the interface between gas phase and hydrate phase. No H2 is found to present in the final hydrate phase at the end of process of CH4-CO2 swap with IGCC syngas.

2016 ◽  
Vol 139 (2) ◽  
Author(s):  
Shi Liu ◽  
Hong Yin ◽  
Yan Xiong ◽  
Xiaoqing Xiao

Heavy duty gas turbines are the core components in the integrated gasification combined cycle (IGCC) system. Different from the conventional fuel for gas turbine such as natural gas and light diesel, the combustible component acquired from the IGCC system is hydrogen-rich syngas fuel. It is important to modify the original gas turbine combustor or redesign a new combustor for syngas application since the fuel properties are featured with the wide range hydrogen and carbon monoxide mixture. First, one heavy duty gas turbine combustor which adopts natural gas and light diesel was selected as the original type. The redesign work mainly focused on the combustor head and nozzle arrangements. This paper investigated two feasible combustor arrangements for the syngas utilization including single nozzle and multiple nozzles. Numerical simulations are conducted to compare the flow field, temperature field, composition distributions, and overall performance of the two schemes. The obtained results show that the flow structure of the multiple nozzles scheme is better and the temperature distribution inside the combustor is more uniform, and the total pressure recovery is higher than the single nozzle scheme. Through the full scale test rig verification, the combustor redesign with multiple nozzles scheme is acceptable under middle and high pressure combustion test conditions. Besides, the numerical computations generally match with the experimental results.


Author(s):  
David J. White ◽  
Richard T. LeCren ◽  
Chaur S. Wen

SolarTurbines Incorporated (Solar) is developing the technologies that are to be used for a highly efficient, recuperated, Advanced Turbine System (ATS) that is aimed at the dispersed power generation market. With ultra-low-emissions in mind the primary fuel selected for this gas turbine engine system is natural gas. Although this gas fired ATS (GFATS) will primarily employ natural gas, the use of other fuels, particularly those derived from coal and renewable resources cannot be overlooked. The enabting technologies necessary to direct-fire coal in gas turbines were developed during the 1980s. This Solar development, co-sponsored by the U.S. Department of Energy (DOE), resulted in the testing of a full size coal-water-slurry fired combustion system. In parallel with this program the DOE funded the development of integrated gasification combined-cycle systems (IGCC). This report describes the limitations of the Solar ATS (recuperated engine) and how these limitations lead to a recommended series of modifications that will allow the use of these alternative fuels. Three approaches have been considered: direct-fired combustion using either a slagging combustor, or a pressurized fluidized bed (PFBC), externally or indirectly fired approaches using pulverized fuel, and external gasification of the fuel with subsequent direct combustion of the secondary fuel. Each of these approaches requires substantial hardware and system modifications for efficient fuel utilization. The integration issues are discussed in the sections below and a recommended approach for gasification is presented.


Author(s):  
Norman Z. Shilling ◽  
Robert M. Jones

Interest in Integrated Gasification Combined Cycle (IGCC) is developing from a need for fuel diversification as a hedge for natural gas price and availability. In IGCC, the gas turbine combustion system is critical to meeting this need. The combustion system also needs to achieve superior environmental performance. This paper discusses specific requirements for IGCC combustion systems that derive from characteristics of gasification fuels and integration with the gasification process. Tradeoffs between system physical design parameters and control strategies must be evaluated in terms of overall functionality of the IGGC process. The key metrics for evaluating “goodness” of design are reliability, availability, maintainability (RAM), robustness to process variability, response to upsets and trips, time to synchronization and startup and shutdown automation. For IGCC, high availability is achieved from the capability of the turbine to robustly co-fire low-calorific synthesis gas with supplementary fuels. Co-firing compensates for shortfalls in gasifier output and maintains continuity of power service during servicing of the gasification plant. Controls need to provide seamless transfers between varying levels of syngas and supplementary fuel, and over the widest range of fuel mixes and power levels. Low calorific fuels provide special challenges to control system design. Variability in syngas composition, temperature and pressure will impact the minimum and maximum nozzle pressure drops and controllability. The effect of fuel constituents on controllability is captured in the modified Wobbe index. Stability and margin against flameout is captured in the upper-to-lower flammability ratio. The paper discusses the restrictions on these parameters for IGCC combustion systems. Control hardware and manifolding necessary with low calorific fuel can potentially conflict with accessibility to the gas turbine. Safe transfers from natural gas to syngas and shutdowns require purge strategies that account for residual energy in ductwork. Finally, the design of the Exxon Singapore IGCC control system is described which provides an extended range of cofiring and load control.


2020 ◽  
pp. 99-111
Author(s):  
Vontas Alfenny Nahan ◽  
Audrius Bagdanavicius ◽  
Andrew McMullan

In this study a new multi-generation system which generates power (electricity), thermal energy (heating and cooling) and ash for agricultural needs has been developed and analysed. The system consists of a Biomass Integrated Gasification Combined Cycle (BIGCC) and an absorption chiller system. The system generates about 3.4 MW electricity, 4.9 MW of heat, 88 kW of cooling and 90 kg/h of ash. The multi-generation system has been modelled using Cycle Tempo and EES. Energy, exergy and exergoeconomic analysis of this system had been conducted and exergy costs have been calculated. The exergoeconomic study shows that gasifier, combustor, and Heat Recovery Steam Generator are the main components where the total cost rates are the highest. Exergoeconomic variables such as relative cost difference (r) and exergoeconomic factor (f) have also been calculated. Exergoeconomic factor of evaporator, combustor and condenser are 1.3%, 0.7% and 0.9%, respectively, which is considered very low, indicates that the capital cost rates are much lower than the exergy destruction cost rates. It implies that the improvement of these components could be achieved by increasing the capital investment. The exergy cost of electricity produced in the gas turbine and steam turbine is 0.1050 £/kWh and 0.1627 £/kWh, respectively. The cost of ash is 0.0031 £/kg. In some Asian countries, such as Indonesia, ash could be used as fertilizer for agriculture. Heat exergy cost is 0.0619 £/kWh for gasifier and 0.3972 £/kWh for condenser in the BIGCC system. In the AC system, the exergy cost of the heat in the condenser and absorber is about 0.2956 £/kWh and 0.5636 £/kWh, respectively. The exergy cost of cooling in the AC system is 0.4706 £/kWh. This study shows that exergoeconomic analysis is powerful tool for assessing the costs of products.


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