Showing papers on "Integrated gasification combined cycle published in 2007"

Combustion processes for carbon capture

Abstract: A review of the technologies for coal-based power generation closest to commercial application involving carbon capture is presented. Carbon capture and storage (CCS) developments are primarily adaptations of conventional combustion systems, with additional unit operations such as bulk oxygen supply, CO2 capture by sorbents, CO2 compression, and storage. They use pulverized coal combustion in entrained flow—the dominant current technology for coal-based power, or gasification in entrained flow, although similar concepts apply to other solid–gas contacting systems such as fluidized beds. Currently, the technologies have similar generation efficiencies and are associated with efficiency penalties and electricity cost increases due to operations required for carbon capture. The R&D challenges identified for the combustion scientist and engineer, with current understanding being detailed, are those of design, optimisation and operational aspects of new combustion and gasification plant, controlling the gas quality required by CCS related units and associated emission compliance, and gas separations. Fundamental research needs include fuel reactions at pressure, and in O2/CO2 atmospheres, as few studies have been made in this area. Laboratory results interpreted and then included in CFD models of combustion operations are necessary. Also identified, but not detailed, are combustion issues in gas turbines for IGCC and IGCC-CCS. Fundamental studies should be a component of pilot-plant and demonstrations at practical scale being planned. Concepts for new designs of combustion equipment are also necessary for the next generation of technologies. The challenges involved with the design and operation of these integrated systems, while supplying electricity on demand, are considerable.

Use of experience curves to estimate the future cost of power plants with CO2 capture

Abstract: Given the dominance of power plant emissions of greenhouse gases, and the growing worldwide interest in CO2 capture and storage (CCS) as a potential climate change mitigation option, the expected future cost of power plants with CO2 capture is of significant interest. Reductions in the cost of technologies as a result of learning-by-doing, RD coal-based integrated gasification combined cycle (IGCC) plants with pre-combustion capture; and coal-fired oxyfuel combustion for new PC plants. We first assess the rates of cost reductions achieved by other energy and environmental process technologies in the past. Then, by analogy with leading capture plant designs, we estimate future cost reductions that might be achieved by power plants employing CO2 capture. Effects of uncertainties in key parameters on projected cost reductions also are evaluated via sensitivity analysis.

System and method for removing carbon dioxide from an atmosphere and global thermostat using the same

Abstract: A system for removing carbon dioxide from an atmosphere to reduce global warming including an air extraction system that collects carbon dioxide from the atmosphere through a medium and removes carbon dioxide from the medium; a sequestration system that isolates the removed carbon dioxide to a location for at least one of storage and which can increase availability of renewable energy or non-fuel products such as fertilizers and construction materials; and one or more energy sources that supply process heat to the air extraction system to remove the carbon dioxide from the medium and which can regenerate it for continued use.

System and method for oxygen separation in an integrated gasification combined cycle system

Abstract: An integrated gasification combined cycle power generation system (100). In one embodiment, shown in FIG. (1), a gasifier (108) is configured to generate synthetic gas (117) from a carbonaceous material (106) and an oxygen supply (109) with a cleaning stage (120) positioned to receive synthetic gas (117) from the gasifier (108) and remove impurities therefrom. A gas turbine combustion system (2) including a turbine (123) is configured to receive fuel (128) from the gasifier (108) and a first air supply (131) from a first air compressor (130). A steam turbine system (4) is configured to generate power with heat recovered from exhaust (140) generated by the gas turbine system (2) and an ion transport membrane air separation unit (110) includes a second air compressor (114) for generating a second air supply (113). A first heat exchanger (118) is configured to cool the synthetic gas (117) prior to removal of impurities in the cleaning stage (120) by flowing the second air supply (113) through the first heat exchanger (118) so that the second air supply (113) receives heat from the synthetic gas (117).

CO2 Sequestration From IGCC Power Plants by Means of Metallic Membranes

Abstract: This paper investigates novel IGCC plants that employ hydrogen separation membranes in order to capture carbon dioxide for long-term storage. The thermodynamic performance of these membrane-based plants are compared with similar IGCCs that capture CO{sub 2} using conventional (i.e., solvent absorption) technology. The basic plant configuration employs an entrained-flow, oxygen-blown coal gasifier with quench cooling, followed by an adiabatic water gas shaft (WGS) reactor that converts most of CO contained in the syngas into CO{sub 2} and H{sub 2}. The syngas then enters a WGS membrane reactor where the syngas undergoes further shifting; simultaneously, H{sub 2} in the syngas permeates through the hydrogen-selective, dense metal membrane into a counter-current nitrogen 'sweep' flow. The permeated H{sub 2}, diluted by N{sub 2}, constitutes a decarbonized fuel for the combined cycle power plant whose exhaust is CO{sub 2} free. Exiting the membrane reactor is a hot, high pressure 'raffinate' stream composed primarily of CO{sub 2} and steam, but also containing 'fuel species' such as H{sub 2}S, unconverted CO, and unpermeated H{sub 2}. Two different schemes (oxygen catalytic combustion and cryogenic separation) have been investigated to both exploit the heating value of the fuel species and produce a CO{sub 2}-rich stream for long termmore » storage. Our calculations indicate that, when 85 vol % of the H{sub 2}+CO in the original syngas is extracted as H{sub 2} by the membrane reactor, the membrane-based IGCC systems are more efficient by about to 1.7 percentage points than the reference IGCC with CO{sub 2} capture based on commercially ready technology.« less

Method for improving gasification efficiency through the use of waste heat

Abstract: A method for recycling the waste heat generated from an external process, which is fuelled by syngas, into a gasification process to enhance the energy density of the syngas produced as well as the overall gasification efficiency of the system. A method is provided for utilizing the waste heat contained in a stream exiting in the syngas fueled process to vaporize water and produce steam. The steam is then upgraded by first exchanging energy with the hot syngas exiting the gasifier and then within the gasifier itself to a temperature where significant steam gasification of the biomass occurs. The process within the gasifier is driven by introducing a small amount of air into the gasifier such that some biomass is directly combusted to provide the heat required by the process.

Should a coal-fired power plant be replaced or retrofitted?

Abstract: In a cap-and-trade system, a power plant operator can choose to operate while paying for the necessary emissions allowances, retrofit emissions controls to the plant, or replace the unit with a new plant. Allowance prices are uncertain, as are the timing and stringency of requirements for control of mercury and carbon emissions. We model the evolution of allowance prices for SO2, NOx, Hg, and CO2 using geometric Brownian motion with drift, volatility, and jumps, and use an options-based analysis to find the value of the alternatives. In the absence of a carbon price, only if the owners have a planning horizon longer than 30 years would they replace a conventional coal-fired plant with a high-performance unit such as a supercritical plant; otherwise, they would install SO2 and NOx, controls on the existing unit. An expectation that the CO2 price will reach $50/t in 2020 makes the installation of an IGCC with carbon capture and sequestration attractive today, even for planning horizons as short as 20 years. A carbon price below $40/t is unlikely to produce investments in carbon capture for electric power.

Influence of Coal as an Energy Source on Environmental Pollution

Abstract: This article considers the influence of coal energy on environmental pollution. Coal is undoubtedly part of the greenhouse problem. The main emissions from coal combustion are sulfur dioxide (SO2), nitrogen oxides (NOx), particulates, carbon dioxide (CO2), and mercury (Hg). Since 1980, despite a 36% increase in electricity generation and more than a 50% increase in coal use, electric utility SO2 and NOx emissions have declined significantly. Globally, the largest source of anthropogenic greenhouse gas (GHG) emissions is CO2 from the combustion of fossil fuels—around 75% of total GHG emissions covered under the Kyoto Protocol. At the present time, coal is responsible for 30–40% of world CO2 emission from fossil fuels.

Compact radial platen arrangement for radiant syngas cooler

Abstract: A radiant synthesis gas (syngas) cooler used to contain and cool the synthesis gas produced by a coal gasification process used in an IGCC power plant employs a compact radial platen arrangement which is less prone to fouling and/or plugging issues.

Baseload coal investment decisions under uncertain carbon legislation.

Abstract: More than 50% of electricity in the U.S. is generated by coal. The U.S. has large coal resources, the cheapest fuel in most areas. Coal fired power plants are likely to continue to provide much of U.S. electricity. However, the type of power plant that should be built is unclear. Technology can reduce pollutant discharges and capture and sequester the CO2 from coal-fired generation. The U.S. Energy Policy Act of 2005 provides incentives for large scale commercial deployment of Integrated Coal Gasification Combined Cycle (IGCC) systems (e.g., loan guarantees and project tax credits). This analysis examines whether a new coal plant should be Pulverized Coal (PC) or IGCC. Do stricter emissions standards (PM, SO2, NOx, Hg) justify the higher costs of IGCC over PC? How does potential future carbon legislation affect the decision to add carbon capture and storage (CCS) technology? Finally, can the impact of uncertain carbon legislation be minimized? We find that SO2, NOx, PM, and Hg emission standards would hav...

Technical and economic optimization of combustion, nitrogen oxides, sulfur dioxide, mercury, carbon dioxide, coal ash and slag and coal slurry use in coal fired furnaces/boilers

Abstract: Improvements in methods by which new or used coal fired boilers whether designed for coal or oil or natural gas firing can substantially improve their technical operation and reduce their capital and operating costs by implementing process steps that (a) minimize the adverse impacts of coal ash and slag on boiler surfaces and particulate emissions, which will improve coal combustion efficiency and facilitate the use of oil or gas designed boilers for coal firing, (b) drastically reduce the loss of water used to transport coal in slurry form to power plants, (c) minimize the combined total nitrogen oxides (NO x ), sulfur dioxide (SO 2 ), mercury (Hg), and carbon dioxide (CO 2 ) emissions, (d) separate and permanently sequester carbon dioxide and (e) improve the coal and solid fuel combustion efficiency. In the method includes whereby slag formed from solid fuel ashes during combustion in boilers or furnaces is suppressed by introducing additional air in a post-primary combustion zone to lower the combustion gas temperatures below temperatures at which the ash softens or liquefies and adheres to boiler or furnace surfaces.

Combined cycle versus one thousand diesel power plants: pollutant emissions, ecological efficiency and economic analysis

Abstract: The increase in the use of natural gas in Brazil has stimulated public and private sectors to analyse the possibility of using combined cycle systems for generation of electrical energy. Gas turbine combined cycle power plants are becoming increasingly common due to their high efficiency, short lead times, and ability to meet environmental standards. Power is produced in a generator linked directly to the gas turbine. The gas turbine exhaust gases are sent to a heat recovery steam generator to produce superheated steam that can be used in a steam turbine to produce additional power. In this paper a comparative study between a 1000 MW combined cycle power plant and 1000 kW diesel power plant is presented. In first step, the energetic situation in Brazil, the needs of the electric sector modification and the needs of demand management and integrated means planning are clarified. In another step the characteristics of large and small thermoelectric power plants that use natural gas and diesel fuel, respectively, are presented. The ecological efficiency levels of each type of power plant is considered in the discussion, presenting the emissions of particulate material, sulphur dioxide (SO 2 ), carbon dioxide (CO 2 ) and nitrogen oxides (NO x ).

Coal to Liquid (CTL): Commercialization Prospects in China

Abstract: Production of fuels/chemicals from syngas (CO + H 2 ) is receiving increased attention with the background of the resource depletion and the unstable prices of petroleum oil. The fuels, especially diesel, obtained from the syngas conversion via Fischer-Tropsch synthesis (FTS), are proved to be of very high quality that will contribute much to environmental protection and raising the energy efficiency in the transportation sector when modern diesel engines are massively applied in vehicles. FTS technologies developed in recent years have reached the stage for the feasibility of construction of large-scale complexes. Under a long-term consideration of developing the field of coal to liquids (CTL), major issues in successfully applying CTL technologies are those controlling the feasibility of all kinds of projects. Points identified are, in general: (1) efficiency advantage over conventional processes (e.g. thermal power generation process); (2) cost and economic benefit; (3) environment advantage. These questions have been better answered using CTL-based poly-generation schemes. Among all the different schemes, in principle, the co-production of liquid fuels and electricity are naturally the main frame. The simple efficiency increase due to the better energy balance in the co-production mode and the environment protection advantage due to the easy-to-apply technology in the pollutant removal and treatment from syngas in a liquid fuel process has projected a bright future even for applying the more capital intensive IGCC + F-T scheme, which can raise the efficiency (to end products) from 43-46 % in either single schemes to about 52-60 %. This new process will guarantee a better solution to environment protection.

Carbon dioxide as fuel for power generation and sequestration system

Abstract: An integrated energy production system and carbon dioxide reaction system for enhancing the energy efficiency and minimizing greenhouse gas emissions of thermally activated power production methods is provided. The system utilizes heat of reaction from the carbon dioxide reaction system to directly reduce the fuel requirements of the thermally activated power production method. The system, when utilizing a reverse fuel cell, achieves concurrent carbon dioxide sequestration resulting from the fuel combustion.

Development of Baseline Performance Values for Turbines in Existing IGCC Applications

Abstract: The U.S. Department of Energy (DOE) Office of Fossil Energy has established projects to develop highly efficient turbines for coal-based fuels in integrated gasification combined-cycle applications. These fuels include coal-derived synthesis gas and pure hydrogen. The projects, with both General Electric and Siemens, have specific performance goals they must strive to attain. In order to ascertain the actual performance improvements that must be realized in these projects to reach the project goals, existing turbine baseline performance must be established. This paper will present the work conducted to establish the baseline performance parameters, and the values of these parameters. Performance parameters and values reported in the open literature will be presented. Parameters that are not available in the literature are also reported and were obtained by using ASPEN PLUS (Aspen Technology, Inc.) and GT-PRO (Thermoflow, Inc.) simulation software. A survey was conducted to obtain available process conditions and parameters related to Simple-Cycle (SC) and Combined-Cycle (CC) gas turbine performance in integrated gasification combined-cycle (IGCC) applications that use coal as the primary fuel source. Information sources include commercial IGCC plants funded through the Clean Coal Technology (CCT) Demonstration Program, a proposed greenfield IGCC plant, NETL system studies, and other open literature sources. The report results can be employed to assist DOE in establishing a “Baseline IGCC Plant Performance Model” for comparisons with future improvements. The year 2010 IGCC performance goals include 45-50% HHV efficiency, $1,000 / kW total capital costs, and near-zero emissions. Contributions toward this goal are provided by DOE’s Gasification and Advanced Turbines programs. Contributions from the Turbines program are targeted to provide 2-3 percentage points improvement in combined-cycle performance by 2010 for synthesis gas applications, and 3-5 percentage points (total) by 2015 for hydrogen fuels. The results are summarized in a series of tables that highlight the information identified that includes gas turbine type, turbine simple-cycle and combined-cycle efficiencies, turbine temperatures (e.g., firing temperature, exhaust temperature), pressure ratio, diluents, fuel composition, ASU integration, coal analysis, emissions, and the overall plant efficiency. The turbines and plants assessed to determine this baseline performance included the U.S.-based GE 7F frame turbines at the Wabash IGCC, Tampa IGCC, and Ashtabula IGCC (Nordic Energy - proposed 2002, Ashtabula, Ohio), as well as two European IGCC plants based on Siemens-Westinghouse V94.2 / V94.3 frame turbines located at the Buggenum IGCC (Netherlands) and Puertollano IGCC (Spain).

Advanced gas turbine combustion system development for high hydrogen fuels

Abstract: Integrated Gasification Combined Cycle (IGCC) technology makes possible the utilization of low cost coal and opportunity fuels, such as petroleum coke, residual oil and biomass, for clean efficient and cost effective electricity generation. Siemens is a leading supplier of products and services for IGCC plants and it is adapting its most advanced gas turbines for successful integration into IGCC plants. To expedite this, Siemens is pursuing combustion system development for application in IGCC plants operating on syngas/hydrogen fuels. Detailed combustion system testing has been carried out during 2005 and 2006 on syngas/hydrogen fuels derived from different feed stocks and gasification processes. The test programs addressed both the Fand G-Class firing temperatures and operating conditions. Fuel transfer capability to and from natural gas, which is the startup and backup fuel, and syngas was explored over the operating range. Optimization studies were carried out with different diluent (H2O and N2) addition rates to determine the effect on emissions and operability. The focus of this development was to ensure that only combustion system modifications would be required for successful enriched hydrogen syngas fuel operation. This paper summarizes the results from the Siemens combustion system development programs to demonstrate that low emissions and wide engine operating range can be achieved on hydrogen fuel operation in advanced 50 Hz and 60 Hz gas turbines in IGCC applications with carbon dioxide capture.