Gasification Combined Cycle Research Articles

Guest Editorial: Nuclear Power and Public Health

Guest Editorial: Nuclear Power and Public Health

The Impact of Combined-Cycle Gas Turbine Short-Term Dynamics on Frequency Control

A model suitable for studying the short-term dynamic response of a combined-cycle gas turbine (CCGT) to a system frequency deviation is developed. The model is used in conjunction with a larger system model to study the impact of increasing levels of CCGT generation on frequency control of a small island system. The study considers single contingencies and does not consider severe cascading-type events. A consequence of the results is that as the number and proportion of base-loaded CCGTs increases, frequency control may become more challenging. The results indicate that with additional CCGTs on the system large frequency excursions will be more likely, and the transmission system operators on the island of Ireland should review their frequency control strategies in the future to avoid the shedding of customers.

New Opportunities Resulting from Cogeneration Systems Based on Biomass Gasification

Cogeneration (COGEN) is defined as the combined production of two forms of energy (electric or mechanical power plus useful thermal energy) in one technological process. The COGEN is considered worldwide as the major option to achieve considerable energy saving with respect to traditional systems. The heat produced from the electricity generating process is captured and utilized to produce domestic purposes and can be used in steam turbines to generate additional electricity. Facilities with COGEN systems use them to produce their own high and low level steam. Currently, advanced biomass gasification and gas turbine combined cycle has been found to be a promising cogenerative conversion technology for the recovery of heat present in biomass fuel. Increased biofuel based cogenerative power production in the future is clearly dependent on the improvement of both performance and investment costs of new high performance technology, and on the nature of policy instruments designed to promote the technology.

Adsorption of CO2 on Zeolites at Moderate Temperatures

Pressure swing adsorption (PSA) and temperature swing adsorption (TSA) are potential techniques for removing carbon dioxide (CO2) from high-pressure fuel gas streams. Zeolites are suitable candidate sorbents for use in these processes; however, the systems would be even more energy efficient if the sorbents were operational at moderate or high temperatures, especially for the removal of CO2 from high-pressure gas streams, such as those from integrated gasification combined-cycle (IGCC) systems. Competitive gas adsorption tests with gas mixtures representing both coal combustion and coal gasification gas streams were conducted in an atmospheric flow reactor with five zeolites at 120 °C. Promising results of preferential adsorption of CO2 were observed with two of these zeolites. However, the CO2 adsorption capacity was significantly lower at 120 °C than at ambient temperature. Volumetric gas adsorption tests of CO2 and nitrogen (N2) on these two zeolites were conducted at 120 °C, up to a pressure of 300 ps...

Wind power planning: assessing long-term costs and benefits

In the following paper, a new and straightforward technique for estimating the social benefit of large-scale wind power production is presented. The social benefit is based upon wind power's energy and capacity services and the avoidance of environmental damages. The approach uses probabilistic load duration curves to account for the stochastic interaction between wind power availability, electricity demand, and conventional generator dispatch. The model is applied to potential offshore wind power development to the south of Long Island, NY. If natural gas combined cycle and integrated gasifier combined cycle (IGCC) are the alternative generation sources, wind power exhibits a negative social benefit due to its high capacity cost and the relatively low emissions of these advanced fossil-fuel technologies. Environmental benefits increase significantly if charges for CO 2 emissions are included. Results also reveal a diminishing social benefit as wind power penetration increases. The dependence of wind power benefits on CO 2 charges, and capital costs for wind turbines and IGCC plant is also discussed. The methodology is intended for use by energy planners in assessing the social benefit of future investments in wind power.

Coal Cell

This article focuses on coal mining that is incredibly disruptive, and coal is heavy and bulky, involving rumbling freight trains to transport it. The idea that fuel cells are every bit as clean as coal is dirty is just as widespread. Fuel cells, after all, take hydrogen and oxygen, and combine those elements to make electricity and water. The program, called the Clean Coal Technology Program, was, in part, an effort to promote commercial-scale integrated gasification combined-cycle (IGCC) coal power plants in the United States. Molten carbonate fuel cell stacks routinely weigh in at 250 kW. For the Wabash River demonstration, eight stacks will be combined for 2 MW. It will be the largest carbonate fuel cell power plant operating on coal in the world. FuelCell Energy has been planning for this sort of project for more than 20 years.

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.

Gas turbine turbocharged by a steam turbine: a gas turbine solution increasing combined power plant efficiency and power

A new design of a combined-cycle gas turbine power plant CCGT with sequential combustion that increases efficiency and power output in relation to conventional CCGT plants is studied. The innovative proposal consists fundamentally in using all the power of the steam turbine to turbocharge the gas turbine. A computer program has been developed to carry out calculations and to evaluate performance over a wide range of operating conditions. The obtained results are compared with those of combined cycles where the gas turbines are not turbocharged and the gas and the steam turbines have independent power exits; the advantages of the new design are stated.

Unification of Gasification Kinetics of Char in CO2 at Elevated Temperatures with a Modified Random Pore Model

The gasification of a char has, so far, been mainly studied at low temperatures and low heating rates, using thermogravimetric analysis. Studies on the gasification of a char in CO2 at elevated temperatures and high heating rates are necessary to develop integrated coal gasification combined-cycle (IGCC) technology. Coal gasification is a very complicated phenomenon, which makes a generalized understanding and description of gasification reactivity of a char very important. Using a unique fluidized bed, the reactivity of a char pyrolyzed at elevated temperatures and high heating rates was investigated. A generalized expression of the gasification reactivity of a char under various conditions was approached with a modified random pore model proposed in this work. It was clarified that a shrinking core model was not appropriate to describe char gasification in CO2. On the basis of our results and those in the literature, it was identified that the char reactivity could be unified with a master curve not onl...

Application of the exergy concept in the petroleum refining and petrochemical industry

In this paper, the past, present and future applications of the exergy concept in applied process research, development and engineering projects in the petroleum refining and petrochemical industry, conducted at the Mexican Petroleum Institute (IMP), are described. These applications are the result of a clear recognition of the challenge represented by the reduction of energy degradation, i.e. the application of the second law of thermodynamics, through the exergy concept, which allows to simultaneously consider the three E's model: energy–economy–ecology. Applications can be grouped in two complementary directions: the first, methodological, direction consists in integrating within general simulation, analysis and optimization programs, the subroutines required to conduct exergy analyses, in order to get in a quick and precise manner, all information required to integrally optimize chemical processes through detailed exergoeconomic and exergoecologic studies. The second direction refers to research and technological development of specific systems and processes, integrally optimum, of which the justification lies on the exergy analysis, i.e. on its capacity to simultaneously consider energy, economy and ecology aspects, such as diabatic distillation, absorption heat pumps, coking–gasification-combined cycle co- and tri-generation, fuel cells, etc.

Parametric analysis of a dual fuel parallel coupled combined cycle

In this paper an optimal interconnection of a coal steam plant with a gas combined cycle is analyzed. In the first part the model of such a connection is introduced in order to calculate the integral and marginal cycle efficiency. A parametric analysis is then performed on the hypothetical plant structure. The main goal of the analysis was to estimate the influence of some parameters on the considered cycle efficiency.

Biomass integrated gasifier combined cycle technology: III. Application in the cane sugar industry

Biomass integrated gasifier combined cycle technology: III. Application in the cane sugar industry

Ash and slag qualities of Australian bituminous coals for use in slagging gasifiers

The suitability of Australian bituminous coals from an ash and slagging viewpoint, has been examined for use in entrained-flow slagging gasifiers which form the basis for more efficient power generation technologies based on integrated gasification-combined cycle (IGCC). Several coal deposits in both NSW and Queensland appear suitable for slag tapping without the addition of any flux. Many more thermal coals are shown to require a limestone flux addition of <3% CaCO 3 by weight of coal and there could well be opportunities to reduce costs of flux addition by blending with other coals with lower ash fusion temperatures. Coal blending to yield a SiO 2/Al 2O 3 ratio of 1.6–2.0 can minimise limestone flux requirements and avoid some limitations which arise from slag crystallisation. Limestone flux requirements can also be reduced by slag tapping at 1500°C rather than 1400°C, but this should be balanced against increased operating costs and losses in cold gas efficiency at higher gasification temperatures. Australian export coals with very low iron contents, after limestone flux addition, appear to have the potential advantage that slag viscosities (and hence slag tapping performance) are essentially independent of variability in coal ash composition. This should lower gasifier operating and maintenance costs, offsetting the costs of flux addition. Ash and slag characteristics and possible strategies for optimum coal use in entrained-flow slagging gasifiers are discussed.

Control and Modelisation of a Biomass-Fuelled IGCC Plant

By signature of the Kyoto protocol, the industrialised countries undertook to reduce the emissions of Greenhouse gases into the atmosphere. As a consequence, the use of fossil fuels must be reduced and substituted by renewable energy. One of the near-future options to produce power from renewable energy sources is to use biomass as a fuel in an Integrated Gasification Combined-Cycle (IGCC) plant. A plant of this type is currently under construction near Pisa and represents a pioneer project in this field. IGCC plants offer a high conversion-efficiency, but are rather complex. The understanding of the main process phenomena and the design of the plant's control system may benefit from a simplified dynamic model described in the paper.

00/01526 Diesel or dual-fuel engine and black liquor gasifier combined cycle

00/01526 Diesel or dual-fuel engine and black liquor gasifier combined cycle

00/01524 Advanced integration concepts for oxygen plants and gas turbines in gasification/IGCC facilities

The commercialization of Integrated Gasification Combined-Cycle (IGCC) power has been aided by concepts involving the integration of a cryogenic air separation unit (ASU) with the gas turbine combined-cycle module. Other processes, such as coal-based ironmaking and combined power and industrial gas production facilities, can benefit from the integration of these two units. It is known and now widely accepted that an ASU designed for elevated pressure service and optimally integrated with the gas turbine can increase overall IGCC power output, increase overall efficiency, and decrease the net cost of power generation compared to non-integrated facilities employing low pressure ASU`s. Depending upon the specific gas turbine, gasification technology, NOx emission specification, and other site specific factors, various degrees of compressed air and nitrogen integration are optimal. Air Products has supplied ASU`s with no integration (Destec/Plaquemine IGCC), nitrogen-only integration (Tampa Electric/Polk County IGCC), and full air and nitrogen integration (Demkolec/Buggenum IGCC). Continuing advancements in both air separation and gas turbine technologies offer new integration opportunities to further improve performance and reduce costs. This paper will review basic integration principles and describe advanced concepts based on emerging high compression ratio gas turbines. Humid Air Turbine (HAT) cycles, and integration of compression heat andmore » refrigeration sources from the ASU. Operability issues associated with integration will be reviewed and control measures described for the safe, efficient, and reliable operation of these facilities.« less

Update on the Progress of the Brazilian Wood BIG-GT Demonstration Project

Biomass integrated gasification-gas turbine (BIG-GT) technology offers the opportunity for efficient and environmentally sound power generation from biomass fuels. Since biomass is “carbon-neutral” it can be used in power generation equipment without contributing to the “greenhouse effect” if it is grown sustainably. The Brazilian BIG-GT initiative is one of a number of initiatives world-wide aimed at demonstrating, and thereby establishing, biomass as an energy resource for power production. The goal of the Brazilian BIG-GT project is to confirm the commercial viability of producing electricity from wood through the use of biomass-fueled integrated gasification combined-cycle (BIG-GT) technology. To fulfil this goal a 32 MWe eucalyptus-fueled demonstration power plant will be built in Brazil on the basis of a design made by TPS Termiska Processer AB (TPS). The first two phases of the project, which included experimental and engineering studies and the basic engineering of the plant, were completed in 1997. The next phase of the project, the construction and commissioning of the plant, is the recipient of a U.S. $35 million grant from the Global Environmental Facility (GEF) of the United Nations Development Program (UNDP), in addition to financing from the World Bank (WB). The plant will be built in Bahia, north-eastern Brazil. The customer of the plant is a consortium, SER—Sistemas de Energia Renova´vel, comprising of CHESF (Companhia Hidro Ele´trica do Sa˜o Francisco), a federally owned electricity generation and distribution company, Electrobras (Centrais Ele´tricas Brasileiras), a holding company comprising of the main Brazilian companies from the electric generation and distribution sector, and Shell Brasil. Start-up of the plant is scheduled for the year 2000. The plant will be based on a TPS designed atmospheric-pressure gasification/gas cleaning process. The product gas will be fired in a modified GE LM 2500 gas turbine. The gasification and gas cleaning process is based on the use of a circulating fluidized bed gasifier, secondary stage catalytic tar cracker and conventional cold filter and wet scrubbing technology. The feedstock to the plant will be mainly eucalyptus wood from a dedicated plantation which is harvested on a three-year cycle. This paper describes the background of the project leading up to the technology selection, the technology that will be employed in the plant and the outline of the economics of this “first-of-a-kind” plant. The progress made in establishing the organization and the formal framework (e.g., securing the electricity and fuel contracts) are also reported. Future projections of likely technological improvements and cost reductions, and their effect on the overall economics of an Nth plant, are presented.

00/00464 Low-grade coal improves the burnability of cement raw meal

This project emphasizes CO2-capture technologies combined with integrated gasification combined-cycle (IGCC) power systems, CO2 transportation, and options for the long-term sequestration of CO2. The intent is to quantify the CO2 budget, or an “equivalent CO2” budget, associated with each of the individual energy-cycle steps, in addition to process design capital and operating costs. The base case is a 458-MW (gross generation) IGCC system that uses an oxygen-blown Kellogg-Rust-Westinghouse (KRW) agglomerating fluidized-bed gasifier, bituminous coal feed, and low-pressure glycol sulfur removal, followed by Claus/SCOT treatment, to produce a saleable product. Mining, feed preparation, and conversion result in a net electric power production for the entire energy cycle of 411 MW, with a CO2 release rate of 0.801 kg/kWhe. For comparison, in two cases, the gasifier output was taken through water-gas shift and then to low-pressure glycol H2S recovery, followed by either low-pressure glycol or membrane CO2 recovery and then by a combustion turbine being fed a high-hydrogen-content fuel. Two additional cases employed chilled methanol for H2S recovery and a fuel cell as the topping cycle, with no shift stages. From the IGCC plant, a 500-km pipeline takes the CO2 to geological sequestering. For the optimal CO2 recovery case, the net electric power production was reduced by 37.6 MW from the base case, with a CO2 release rate of 0.277 kg/kWhe (when makeup power was considered). In a comparison of air-blown and oxygen-blown CO2-release base cases, the cost of electricity for the air-blown IGCC was 56.86 mills/kWh, while the cost for oxygen-blown IGCC was 58.29 mills/kWh. For the optimal cases employing glycol CO2 recovery, there was no clear advantage; the cost for air-blown IGCC was 95.48 mills/kWh, and the cost for the oxygen-blown IGCC was slightly lower, at 94.55 mills/kWh.

00/00469 Advanced hot gas filter development

Coal is the most abundant fossil-fuel resource in the United States. `Clean coal` technologies, such as pressurized fluidized-bed combustion (PFBC) and integrated gasification combined-cycle (IGCC), require a hot gas filter to remove the corrosive and erosive coal ash entrained in the combustion gas stream. These hot gas filters, or candle filters, must be cost-effective while able to withstand the effects of corrosion, elevated temperature, thermal shock, and temperature transients. Ash loadings may range from 500 to 10,000 ppm by weight, and may contain particles as fine as 0.008 mils. The operating environment for the hot gas filter can range in pressure from 10 to 20 atm, in temperatures from 700 to 1750{degrees}F, and can be oxidizing or reducing. In addition, the process gases may contain volatile chloride, sulfur, and alkali species. Field testing of various commercially available, porous, ceramic filter matrices has demonstrated a loss of up to 50 percent of as-manufactured strength after 1,000 to 2,000 hours of exposure to these operating conditions, although full-scale elements have remained intact during normal process operations. Ultramet, a small business specializing in advanced materials R&D, has developed a new class of hot gas filter materials that offers lower back-pressure, higher permeability, longer life, and high filtration efficiency in the PFBC and IGCC environments. Subscale Ultrafoam Duplex Filter elements have undergone accelerated corrosion testing at temperatures of up to 2370{degrees}F (at Ultramet), and have been subjected to over 2,800 hours of exposure to hot PFBC gases (in the Westinghouse Advanced Particulate Filtration System at Brilliant, OH) without any loss in strength in either case. The Ultrafoam Duplex Filter matrix demonstrated 100 percent particle- capture efficiency of coal ash, and had an initial pressure drop of 0.1 to 0.6 in-wc/fpm. The Ultrafoam Duplex Filter is composed of a chemical vapor deposition (CVD), silicon carbide (SiC), reticulated, open-cell foam filter body supporting a porous mullite membrane filter. The reticulated foam structure is 70 to 90 percent porous, enabling high permeability, while the 3-D interconnected cellular lattice resists crack propagation. The CVD SiC material is fine-grained for maximum strength and corrosion resistance, and has no binders or impurities. The porous, mullite, membrane filter is impregnated into the outer surface of the CVD SiC Ultrafoam filter element. The membrane bonds to the foam ligaments, while the foam ligaments reinforce and support the membrane. The mullite membrane, which acts as a barrier filter, is resistant to thermal shock and corrosion. The thin membrane minimizes pressure drop and thermal gradients. The composite Ultrafoam Duplex Filter was designed to combine optimal material selection with functional structural design to maximize corrosion resistance, thermal shock resistance, strength, toughness, and life while minimizing pressure drop and weight. Oxidation rate, corrosion resistance, creep strength, compressive strength, and C-ring strength of the CVD SiC Ultrafoam filter body, and pressure drop and filtration efficiency for subscale Ultrafoam Duplex Filter elements, are reported. Future work is targeted at the construction of full-scale hot gas filters, and will include further strength and accelerated corrosion testing of subscale sections of the filter body, the membrane, and the composite duplex filter elements.

Viscosity measurements and empirical predictions for fluxed Australian bituminous coal ashes

Recent interest in the suitability of Australian bituminous coals for use in integrated gasification-combined cycle (IGCC) technologies has provided the opportunity to determine viscosity data for a range of coal ashes slags fluxed with limestone at the tapping temperatures of entrained flow gasifiers. Experimental viscosity measurements have been made over a range of slag compositions covering the anorthite region at the 0–2.5, 2.5–5, 5–7.5 and 7.5–10wt% FeO levels of the quaternary SiO2–Al2O3–CaO–FeO system. Contour plots of viscosities at 1450°C for the four FeO ranges are presented as an example for predicting slag behaviour in entrained flow gasifiers. The viscosity measurements have also been fitted empirically using a modified Urbain treatment to give separate models for the four FeO levels. Polynomial expressions are given for the evaluation of viscosities covering the temperature range 1400–1550°C for slags within the compositional range used in the derivation.