Journal of Engineering for Power
ISSN : 0022-0825
Published by: ASME International (10.1115)
Total articles ≅ 2,962
Latest articles in this journal
Journal of Engineering for Power, Volume 105, pp 797-805; https://doi.org/10.1115/1.3227484
Laboratory tests of catalytic combustors with distillate fuel have achieved ultralow NOx formation at catalytic reactor exit temperatures and combustion efficiencies consistent with state-of-the-art gas turbine requirements. Concomitant with these features, however, are design limitations such as narrow turn-down range and unique reactor mounting requirements. This paper presents fully analyzed conceptual design solutions to these problems within the constraints of fixed geometry, full catalytic combustion over 80 percent of the turbine load range, and retrofit to an existing gas turbine. The combustor design incorporates (a) a gutter stabilized pilot burner downstream of the reactor for operation from ignition to full-speed no-load, (b) a segmented fuel-air preparation system for fuel staging of the reactor, (c) a reactor mounting system which accommodates thermal growth and start-up and shutdown transients, and (d) a graded cell reactor. These features were achieved while maintaining low reactor face velocities and system pressure drops.
Journal of Engineering for Power, Volume 105, pp 806-815; https://doi.org/10.1115/1.3227485
The only commercially running closed-cycle gas turbine in the world delivering electricity as well as heat to a public utility and a heating network, is the heat and power station in Coburg, West Germany. The plant is fired exclusively with pulverized coal and uses air as the working medium. It has a maximum continuous electric power output of 6.6 MW into the grid and up to 16 MW of direct heating capacity into the town’s heating network. The plant has accumulated 150,000 operating hours to date (approximately 7000 hrs per year); it is scheduled to remain in service during the following years due to its excellent performance. Since relatively little has been published about the plant in the technical literature, a report about its design and operating experience is presented here.
Journal of Engineering for Power, Volume 105, pp 821-825; https://doi.org/10.1115/1.3227487
Studies of combined cycle electic power plants have shown that increasing the firing temperature and pressure ratio of the gas turbine can substantially improve the specific power output of the gas turbine as well as the combined cycle plant efficiency. Clearly this is a direction in which we can proceed to conserve the world’s dwindling petroleum fuel supplies. Furthermore, tomorrow’s gas turbines must do more than operate at higher temperature; they will likely face an aggressive hot gas stream created by the combustion of heavier oils or coal-derived liquid or gaseous fuels. Extensive tests have been performed on two rotating turbine rigs, each with a transpiration air cooled turbine operating in the 2600 to 3000°F (1427 to 1649°C) temperature range at increasing levels of gas stream particulates and alkali metal salts to simulate operation on coal-derived fuel. Transpiration air cooling was shown to be effective in maintaining acceptable metal temperatures, and there was no evidence of corrosion, erosion, or deposition. The rate of transpiration skin cooling flow capacity exhibited a minor loss in the initial exposure to the particulate laden gas stream of less than 100 hours, but the flow reduction was commensurate with that produced by normal oxidation of the skin material at the operating temperatures of 1350°F (732°C). The data on skin permeability loss from both cascade and engine tests compared favorably with laboratory furnace oxidation skin specimens. To date, over 10,000 hr of furnace exposure has been conducted. Extrapolation of the data to 50,000 hr indicates the flow capacity loss would produce an acceptable 50°F (10°C) increase in skin operating temperature.
Journal of Engineering for Power, Volume 105, pp 851-858; https://doi.org/10.1115/1.3227492
High-cycle pressure-ratio (38–42) gas turbines being developed for future aircraft and, in turn, industrial applications impose more critical disk and casing cooling and thermal-expansion problems. Additional attention, therefore, is being focused on cooling and the proper selection of materials. Associated blade-tip clearance control of the high-pressure compressor and high-temperature turbine is critical for high performance. This paper relates to the use of extracted steam from a steam turbine as a coolant in a combined cycle to enhance material selection and to control expansion in such a manner that the cooling process increases combined-cycle efficiency, gas turbine output and steam turbine output.
Journal of Engineering for Power, Volume 105, pp 713-718; https://doi.org/10.1115/1.3227472
A brief status report on the work concerning design codes for HTR components with service temperatures above 800°C is given. The evaluation of experimental test work and preliminary time-dependent design data are reviewed and some design analyses for an IHX concerning fatigue, creep buckling, and creep ratcheting are described as a basis for critical discussion of some features of ASME Code Case N 47.
Journal of Engineering for Power, Volume 105, pp 726-734; https://doi.org/10.1115/1.3227474
High-temperature, gas-cooled reactors (HTGR’s) are uranium/thorium-fueled, graphite-moderated, helium-cooled systems capable of producing high-temperature primary coolant. Several variants of this system are under active development in the United States and worldwide. In one version, the primary coolant heat is transferred to steam generators producing 538°C/16.5 MPa steam for use in electricity generation or process heat applications. The materials and design technology for steam generators in this system are well developed, relying heavily upon prior experience with fossil-fired steam generators and the steam generators of the commercial HTGR’s. The major work that remains to be done is to complete qualification of the materials and to respond to evolving rules pertinent to elevated-temperature nuclear design and construction. Other versions of the HTGR generate much higher primary coolant gas temperatures (850° to 950°C) and exchange this heat, through intermediate heat exchangers (IHX’s), to a secondary loop for higher temperature process heat applications. Although IHX’s for these systems are typically pressure-balanced (low-stress) units, their design involves several challenges, including the potential interactions between structural materials and impurities present in the HTGR primary coolant. Considerable work is required to qualify materials for IHX applications, including detailed mechanical property characterization, determination of environmental influences on performance, provision of welding materials and procedures for producing joints of adequate strength and integrity, and provisions for wear protection. Some of the work currently under way addressing these issues is described.
Journal of Engineering for Power, Volume 105, pp 742-747; https://doi.org/10.1115/1.3227476
An experimental apparatus was used to simulate the annular crevice formed by a heated tube and drilled tube support plate (TSP) in a pressurized water reactor recirculating steam generator. The aim of the experiment was to explore the conditions required for the formation and maintenance of a dry region. Water at 0.69 MPa or atmospheric pressure was circulated through the crevice. Visual observations and tube wall temperature measurements were obtained and compared to synthesize a description of the crevice boiling processes. It was determiend that a stable dry patch exists about a line of contact between tube and TSP above a wall superheat of 2–3°C. However, separating the tube and TSP by about 0.025 mm allows the dry patch to be rewet.
Journal of Engineering for Power, Volume 105, pp 748-754; https://doi.org/10.1115/1.3227477
An experimental apparatus was used to simulate the annular crevice formed by a heated tube and drilled tube support plate (TSP) in a pressurized water reactor recirculating steam generator. A previous paper  has described the stable dryout phenomena which occur. This paper discusses the heat transfer mechanisms in the contact and wide gap regions of the crevice. Changes in flow rate and inlet enthalpy are found to have little effect on the patch extent and contact line temperature, while an increase in diametral gap size decreases both. Increasing the thermal conductivity of the TSP also reduces the contact line temperature, but does not affect the wide gap region.
Journal of Engineering for Power, Volume 105, pp 755-762; https://doi.org/10.1115/1.3227478
Denting studies have been undertaken in order to assess the influence of the most important parameters which could initiate corrosion of the carbon steel occurring in the tube-tube support plate crevices of some PWR steam generators. Tests have been carried out in model boilers where feedwater was polluted with sea or river water. Specific effects of chloride or sulfate and influence of oxygen content, magnetite addition and pH value were investigated. In magnetite prepacked crevices, denting is obtained within 1000 hrs for seawater pollution of 0.3 ppm chloride at the blowdown. In neutral chloride or in river water, denting is observed only with oxygen addition. Denting prevention is effective in the case of an on-line addition of phosphate, boric acid, or calcium hydroxide. For denting stopping, boric acid or calcium hydroxide is efficient even with a high seawater pollution. Soaks cannot stop denting if they are not followed by an on-line treatment (boric acid, calcium hydroxide). With quadrifoil holes, denting doesn’t occur. In very severe test conditions, 13 percent Cr steel can be corroded, but the corrosion rate is low and oxide morphology is different from that growing on carbon steel.
Journal of Engineering for Power, Volume 105, pp 763-770; https://doi.org/10.1115/1.3227479
Laboratory testing at Combustion Engineering has indicated promise in controlling simulated steam generator tube denting through chemical neutralization. Testing was limited to on-line treatment, and two neutralizers have been evaluated: (i) calcium hydroxide, and (ii) boric acid. On-line treatment with calcium hydroxide successfully halted active denting whenever the bulk calcium concentration (in ppm) equaled or exceeded the bulk chloride concentration (in ppm). Calcium hydroxide also was effective as an alternative to ammonia as a pH controlling agent in two tests conducted without ingress of chloride. On-line treatment with boric acid consisted of a four-day soak at simulated low (approximately 30 percent) power with 50 ppm B followed by one month full-power operation with 10 ppm B. This treatment also halted denting. Nondestructive and destructive examination of test boilers gave no indication of adverse side effects associated with either neutralizer.