ISSN:0960-3409    

DOI:10.1080/09603409.1993.11689430

出版商:Taylor&Francis    

年代:1993

数据来源: Taylor

摘要:

Since proven world coal resources are sufficient to produce electricity until well into the twenty-second century, coal will remain the primary fossil fuel for power generation. Growing concern about environmental pollution will inevitably lead to more advanced and cleaner cycles. Basic considerations for advanced coal fired plants are maximum availability and efficiency, minimum environmental emissions, optimal total costs (investment, operational and maintenance costs) and maximum utilization of waste products. The currently applied pulverized coal fired steam cycle plant will further develop from supercritical units in the early 1990s (27.5 MPa, 545°C/570°C) to ultrasupercritical double reheat units in the next century (35.0 MPa, 600°C/600°C). By additional improvements, such as increased feed-water temperature, improved turbine blading, waste heat recovery devices and better back-end designs, the net thermal efficiency can be increased further. Gas turbines and fuel cells provide a new basis for efficiency improvement early next century. Combined cycle techniques based on pressurized fluidized bed combustion or gasification and pressurized entrained bed gasification are expected to be the competitive technologies for the next decades. The coal gasification technology has advantages over the coal combustion technology. First, the potential to exploit a high gas inlet temperature for the gas turbine (high efficiency) and second, the ability to utilize the syngas for high efficiency cycles such as the fuel cell technology or in combination with chemical processes during night shift (powerplex principle). Finally, the removal of CO2from the syngas is potentially economically feasible. Disadvantages of coal gasification are the high capital costs and the complexity of the installation. Integrated gasification combined cycle plants are close to commercialization. They promise major reductions in emissions and interesting options for improved efficiency. Materials are a key element in further development.

ISSN:0960-3409    

DOI:10.1080/09603409.1993.11689431

出版商:Taylor&Francis    

年代:1993

数据来源: Taylor

摘要:

Second-generation pressurized fluidized bed combustion (PFBC) plants promise higher efficiency with lower costs of electricity and lower stack emissions. With a 16.55 MPa/538°C/538°C/63.5mmHg (2400 psig/1000°F/1000°F/2.5 in Hg) conventional steam cycle and a 3% sulfur Pittsburgh No. 8 coal, a 45% efficiency and a cost of electricity about 20% lower than that of a pulverized coal fired plant with stack gas scrubbing are being projected. Foster Wheeler Development Corporation has constructed, and is operating, a second-generation PFBC pilot plant at the Foster Wheeler research facility (the John Blizard Research Center) in Livingston, NJ, USA. Initial results of the pilot plant carbonizer test programme supporting the development of this new type of plant are presented.

ISSN:0960-3409    

DOI:10.1080/09603409.1993.11689432

出版商:Taylor&Francis    

年代:1993

数据来源: Taylor

摘要:

The PRENFLO coal gasification process and experience from the Fürstenhausen demonstration plant in Germany are described. The PRENFLO process, a further development of the Koppers-Totzek process, is based on the entrained-flow principle with dry fuel dust feeding. Experience from the two demonstration plants in Hamburg and Fürstenhausen supplied the main data for the first commercial-size PRENFLO plant for Elcogas, S.A., in Puertollano, Spain. With a net electrical output of 300 MW the Puertollano plant is the world's highest capacity combined-cycle power plant based on coal. In particular, some results from the 1992 test programme in the Fürstenhausen plant are presented.

ISSN:0960-3409    

DOI:10.1080/09603409.1993.11689433

出版商:Taylor&Francis    

年代:1993

数据来源: Taylor

摘要:

An integrated coal gasification combined cycle system has major efficiency and environmental advantages and is therefore regarded as a natural candidate for new coal-based power generation projects. The Shell Coal Gasification Process (SCGP) is in the forefront of coal gasification technology. Wide experience was gained with development (Shell Amsterdam Laboratory), pilot (Deutsche Shell, Harburg refinery) and demonstration units (SCGP-1, Houston, USA). SCGP flexibility has been demonstrated for feeds ranging from bituminous coals to lignites and petroleum coke, and the process is well suited for combined cycle power generation. The first commercial application of the Shell technology is presently under construction in the Netherlands by Demkolec for the Dutch utilities. The plant is scheduled to start up in the second half of 1993.

ISSN:0960-3409    

DOI:10.1080/09603409.1993.11689434

出版商:Taylor&Francis    

年代:1993

数据来源: Taylor

摘要:

The thermodynamics, kinetics and mechanisms of oxidation and corrosion processes are described. These processes can occur in oxidizing, oxidizing-sulfidizing, oxidizing-chloridizing and oxidizing-carburizing atmospheres at 400 to 700°C on ferritic and austenitic chromia-forming steels.

ISSN:0960-3409    

DOI:10.1080/09603409.1993.11689435

出版商:Taylor&Francis    

年代:1993

数据来源: Taylor

摘要:

A principal reason for the interest in iron aluminides is their potential to resist corrosion in aggressive high-temperature environments. Accordingly, the development programme for this class of alloys has included an investigation of the corrosion properties in mixed oxidant (H2S-H2−H20) environments. Corrosion studies were initially directed at Fe3A1 and FeA1, including effects of third element additions such as Cr, Nb, Mo, Zr and Y. Iron-aluminium alloys with lower aluminium concentrations (between 16 and 22 atom%) were next investigated to establish the minimum aluminium concentration needed to resist sulfidation and oxidation. The results have shown that alloys containing≥18% A1 are uniquely resistant to H2S-containing environments at 800°C. Chromium adversely affected the corrosion resistance in this mixed gas environment, although this effect was partially offset by the addition of molybdenum. Zirconium and yttrium had no significant effect on the corrosion rate under the same temperature and environmental conditions. Metallographic and chemical analyses of the corrosion product scales and underlying alloy were performed to determine the roles of the respective metallic elements in the corrosion process in H2S-H2−H20. These results, together with weight change determinations, are discussed in terms of the apparent corrosion mechanisms and optimization of alloy composition for exposure to gasifier environments.

ISSN:0960-3409    

DOI:10.1080/09603409.1993.11689436

出版商:Taylor&Francis    

年代:1993

数据来源: Taylor

摘要:

Corrosion of metallic structural materials at elevated temperatures in complex gas environments of coal gasification is a potential problem. The use of appropriate corrosion-resistant coatings on metallic components offers an avenue to minimize material degradation and extend component life. The purpose of this paper is to review the current status on development and performance coatings in environments typical of coal gasification systems. The paper discusses the complexity of gasification environments, coating requirements for acceptable performance, coating methods, and corrosion performance of several of the coatings. Examples illustrate the morphology and corrosion performance of coating/structural alloy combinations exposed in simulated gasification environments and the results are used to identify promising coatings for application in gasification systems.

ISSN:0960-3409    

DOI:10.1080/09603409.1993.11689437

出版商:Taylor&Francis    

年代:1993

数据来源: Taylor

摘要:

This paper deals with an investigation into the protective limit of an oxide scale preformed on the ODS alloy MA 956. The experiments were carried out under creep conditions for different strains and strain rates at 600°C up to 8000 h exposure. The possible consequences of scale rupture on the quality of protection have been analysed by exposing the alloy in an S-O-C-bearing gas of low oxygen and medium sulfur potentials which was intended to simulate a coal-gasification atmosphere. The results have shown that MA 956 forms an adherent A12O3scale about 1.5μm thick after preannealing for 2h at 1100°C. This scale exhibited full protection even after long-term exposure. Scale cracking was first observed in the range 0.5−0.6% total strain. No influence on the critical strain value due to strain rate could be observed in the range 10−10−2×10−7s−1. Cracking could be identified by surface examination due to the external corrosion taking place along the cracks. The onset of corrosion resulting from scale cracking was characterized by the formation of Cr-rich (Cr, Fe)-sulfides on the outside of the scale. With progressing time, external Fe-rich (Fe, Cr)-sulfides were also observed, and internal oxidation and sulfidation occurred in parallel. With larger strains, e.g. more than about 1%, indications of scale spallation were found.

ISSN:0960-3409    

DOI:10.1080/09603409.1993.11689438

出版商:Taylor&Francis    

年代:1993

数据来源: Taylor

摘要:

The behaviour of high alloy steels, especially ferritic, A1-containing alloys based upon Fecralloy®, has been studied in simulated coal gasification atmospheres (CGAs) containing HC1 at 450°C. In addition, alloy modifications with increased Si and Cr levels were studied. Samples were also exposed in gasification pilot plants to compare with the behaviour observed in the laboratory. In CGA tests containing 1000 ppm HC1, which simulated conditions in an atmospheric gasifier, all the Fecralloy-based alloys tested exhibited low rates of attack, so these materials would be suitable for long-term exposure in these conditions. It was shown that, while initial formation of sulfides occurred, an Al-rich layer was eventually established that was rate controlling and prevented further formation of sulfides. Prior oxidation before exposure to the CGA prevented sulfide formation, and the scale composition and morphology that were observed in this case correlated well with those observed in the pilot plant. At levels of HC1 that would correspond to the operation of a pressurized gasifier, greatly increased rates of attack were observed and a thick sulfide layer was developed which, during the early stages of the reaction, was disrupted by chloride formation. The mass change data indicated that rates of attack for all the alloys examined were considered borderline for this application.

ISSN:0960-3409    

DOI:10.1080/09603409.1993.11689439

出版商:Taylor&Francis    

年代:1993

数据来源: Taylor