scholarly journals The Gas Turbine Heat Exchanger in the Fluidized Bed Combustor

1982 ◽  
Author(s):  
C. F. Holt ◽  
A. A. Boiarski ◽  
H. E. Carlton
Keyword(s):  
Heat Exchanger ◽  
Oxygen Partial Pressure ◽  
Partial Pressure ◽  
Gas Turbine ◽  
Fluidized Bed ◽  
Development Program ◽  
Low Oxygen ◽  
Bed Temperature ◽  
Technical Effort ◽  
Fluidized Bed Combustor

In a current research and development program a coal fired atmospheric fluidized bed combustor is being designed to supply the heat to a closed cycle gas turbine cogeneration system. The major technical effort is directed towards the design of the in-bed heat exchanger, which is required to operate near bed temperature. This high temperature (850 C) exposes the heat exchanger tubes to potentially severe sulfidation. The corrosion behavior depends upon the intimate details of the bed environment and may be related to the occurrence of localized areas of low oxygen partial pressure and high sulfur partial pressure. This paper describes a series of measurements of oxygen partial pressure at various locations within a fluidized bed. The bed, containing densely packed heat exchanger tubes, was operated under various conditions to observe the effect of coal mixing and devolatilization on local oxygen activity. Substantial variations of oxygen partial pressure (below 10−14 atmospheres) were observed. It was noted that these locally severe variations could be substantially modified by changes in coal mixing (as through coal port design). The experiments with varying coal size suggest that rapid devolatilization is desirable and would reduce the extent of locally corrosive environments.

The Gas Turbine Heat Exchanger in the Fluidized Bed Combustor

1983 ◽  
Vol 105 (3) ◽  
pp. 438-445 ◽  
Author(s):  
C. F. Holt ◽  
A. A. Boiarski ◽  
H. E. Carlton
Keyword(s):  
Heat Exchanger ◽  
Oxygen Partial Pressure ◽  
Partial Pressure ◽  
Gas Turbine ◽  
Fluidized Bed ◽  
Development Program ◽  
Low Oxygen ◽  
Bed Temperature ◽  
Technical Effort ◽  
Fluidized Bed Combustor

In a current research and development program a coal-fired atmospheric fluidized bed combustor is being designed to supply the heat to a closed cycle gas turbine cogeneration system. The major technical effort is directed towards the design of the in-bed heat exchanger, which is required to operate near bed temperature. This high temperature (850° C) exposes the heat exchanger tubes to potentially severe sulfidation. The corrosion behavior depends upon the intimate details of the bed environment and may be related to the occurrence of localized areas of low oxygen partial pressure and high sulfur partial pressure. This paper describes a series of measurements of oxygen partial pressure at various locations within a fluidized bed. The bed, containing densely packed heat exchanger tubes, was operated under various conditions to observe the effect of coal mixing and devolatilization on local oxygen activity. Substantial variations of oxygen partial pressure (below 10−14 atmospheres) were observed. It was noted that these locally severe variations could be substantially modified by changes in coal mixing (as through coal port design). The experiments with varying coal size suggest that rapid devolatilization is desirable and would reduce the extent of locally corrosive environments.

scholarly journals The Corrosive Environment in the Fluidized-Bed Heat-Exchanger for CCGT Service

1983 ◽  
Author(s):  
M. A. Rocazella ◽  
I. G. Wright ◽  
C. F. Holt
Keyword(s):  
Heat Exchanger ◽  
Oxygen Partial Pressure ◽  
Partial Pressure ◽  
Fluidized Bed ◽  
Mechanical Damage ◽  
Oxygen Probe ◽  
Erosion Process ◽  
Bed Material ◽  
Fluidized Bed Combustor

Corrosion and combustion diagnostic data were gathered in Battelle’s 0.6m diameter coal-fired atmospheric fluidized-bed combustor (AFBC). Corrosion probes, constructed from ring specimens of candidate heat-exchanger alloys, were exposed to the fluidized-bed environment during three different combustion experiments (50%, 20% and 0% excess air). An in-situ oxygen probe was used to monitor the oxygen partial pressure at the exposure locations. Two different mechanisms of material degradation were identified, i.e., both corrosion and erosion. An adherent deposit of bed material formed on all areas of the corrosion probes. The corrosion behavior of the alloys beneath the deposit, and the corresponding corrosion product morphologies, appeared to correlate well with predictions based on the oxygen partial pressure measurements from the exposure location. The results suggest the oxygen probe may be a useful diagnostic tool for locating regions with high corrosive potentials. However, the upstream faces of the corrosion probes were subjected to enhanced mechanical damage, and this periodic removal of both the deposit and corrosion products resulted in significantly more metal degradation. Also, this corrosion/erosion process may locally deplete the alloy in chromium, leaving it susceptible to severe sulfidation and/or accelerated oxidation. It was suggested that these locations would be the first to experience heat-exchanger tube failure, and the coupled corrosion/erosion process would be the failure mechanism.

Gas Turbine Blade Materials’ Corrosion in the Effluent From a Pressurized Fluidized Bed Combustor

1984 ◽  
Author(s):  
R. L. McCarron ◽  
R. P. Brobst
Keyword(s):  
Corrosion Resistance ◽  
Gas Turbine ◽  
Fluidized Bed ◽  
Diffusion Coating ◽  
Operating Conditions ◽  
Platinum Aluminide ◽  
Bed Temperature ◽  
Overlay Coatings ◽  
Cobalt Base ◽  
Fluidized Bed Combustor

Two nominally 200-hour tests were conducted in the General Electric Company’s Pressurized Fluidized Bed (PFB) Coal Combustion facility in Malta, NY. The purpose of the tests was to evaluate the influence of bed operating temperature and dolomite composition on the degradation of gas turbine vane and blade base alloys and protective coating/cladding systems in the effluent from a PFB. Operating conditions were as follows: 1) 1710°-1770°F (932°C-966°C) bed temperature and Pfizer dolomite (0.1 wt% sodium plus potassium), and 2) 1630°-1690°F (888°-921°C) bed temperature and Tymochtee dolomite (0.9 wt% sodium plus potassium). Brookville seam coal with 4.5 wt% sulfur, 0.3 wt% alkali, and 0.17 wt% chlorine was used in both tests. Bare nickel and cobalt-base vane and blade alloys were susceptible to hot corrosion over the entire temperature range investigated, 1100°-1600°F (593°-871°C). CoCrAlY and FeCrAlY overlay coatings showed good corrosion resistance at temperatures above 1450°F, but were susceptible to pitting attack at lower temperatures. A platinum-aluminide diffusion coating showed excellent corrosion resistance at all temperatures.

scholarly journals Coal-Fired Gas Turbine for Locomotive Propulsion

1987 ◽  
Author(s):  
Leon Green
Keyword(s):  
Heat Exchanger ◽  
Gas Turbine ◽  
Fluidized Bed ◽  
Power Cycle ◽  
Water Slurry ◽  
Bulk Solid ◽  
Solid Coal ◽  
Coal Water Slurry ◽  
Pressurized Combustion ◽  
Fluidized Bed Combustor

Substitution of a deeply-cleaned coal-water slurry fuel for bulk solid coal in an atmospheric fluidized-bed combustor permits a sequence of evolutionary steps which can convert the conventional AFBC into a pressurized, combustion-stirred, fluidized-bed heat exchanger compact enough to propel a standard locomotive by use of a closed Brayton power cycle.

Quantitative evaluation of the oxidation behavior of ZrB2-15 vol.%SiC at a low oxygen partial pressure

Vacuum ◽  
2013 ◽  
Vol 88 ◽  
pp. 98-102 ◽  
Author(s):  
Ai Momozawa ◽  
Rong Tu ◽  
Takashi Goto ◽  
Yuuki Kubota ◽  
Hiroshi Hatta ◽  
...  
Keyword(s):  
Oxygen Partial Pressure ◽  
Partial Pressure ◽  
Quantitative Evaluation ◽  
Oxidation Behavior ◽  
Low Oxygen

Enhanced superconductivity in Nd1+xBa2-xCu3O7+δby low oxygen partial pressure annealing

1994 ◽  
Vol 23 (11) ◽  
pp. 1117-1120 ◽  
Author(s):  
M. J. Kramer ◽  
A. Karion ◽  
K. W. Dennis ◽  
M. Park ◽  
R. W. McCallum
Keyword(s):  
Oxygen Partial Pressure ◽  
Partial Pressure ◽  
Low Oxygen ◽  
Enhanced Superconductivity

Experimental Study on Compact External Heat Exchanger for a 4 MWth Circulating Fluidized Bed Combustor

2013 ◽  
Vol 448-453 ◽  
pp. 3259-3269
Author(s):  
Zhi Wei Li ◽  
Hong Zhou He ◽  
Huang Huang Zhuang
Keyword(s):  
Heat Transfer ◽  
Heat Exchanger ◽  
Fluidized Bed ◽  
Heat Transfer Rate ◽  
Transfer Rate ◽  
Cooling Water ◽  
External Heat ◽  
Circulating Ash ◽  
Fluidized Bed Combustor ◽  
External Heat Exchanger

The characteristics of the external heat exchanger (EHE) for a 4 MWth circulation fluidized bed combustor were studied in the present paper. The length, width and height of EHE were 1.5 m, 0.8 m and 9 m, respectively. The circulating ash flow passing the heating surface bed could be controlled by adjusting the fluidizing air flow and the heating transferred from the circulating ash to the cooling water. The ash flow rate passing through the heat transfer bed was from 0.4 to 2.2 kg/s. The ash average temperature was from 500 to 750 °C. And the heat transfer rate between the ash and the cooling water was between 150 and 300 W/(m2·°C). The relationships among the circulating ash temperature, the heat transfer, heat transfer rate, the heat transfer coefficient and the circulating ash flow passing through the heating exchange cell were also presented and could be used for further commercial EHE design.

scholarly journals Comparison of Various Fluidized Bed Combustor-Gas Turbine Systems

1985 ◽  
Author(s):  
Arthur P. Fraas
Keyword(s):  
Gas Turbine ◽  
Fluidized Bed ◽  
Thermal Efficiency ◽  
Combustion Efficiency ◽  
Capital Cost ◽  
Inlet Temperature ◽  
Extensive Experience ◽  
Helium Gas ◽  
Steam Plant ◽  
Fluidized Bed Combustor

Pressurizing a fluidized bed combustor with a gas turbine greatly improves both sulfur retention and combustion efficiency. Operating the gas turbine with a high inlet temperature (e.g. 900°C) would yield a thermal efficiency about four points higher than for an atmospheric furnace, but 40 y of experience have failed to solve problems with flyash erosion and deposits. Extensive experience such as that with fluidized bed catalytic cracking units indicates that the gas turbine blade erosion and deposit problems can be handled by dropping the turbine inlet temperature below 400°C where the turbine delivers just enough power to drive the compressor. The resulting thermal efficiency is about half a point higher than for an atmospheric bed, and the capital cost of the FBC-related components is about 40% lower. While a closed-cycle helium gas turbine might be used rather than a steam cycle, the thermal efficiency would be about four points lower and the capital cost of the FBC-related components would be roughly twice that for the corresponding steam plant.

Tensile Properties and Creep Behavior of SiC-Based Fibers under Various Oxygen Partial Pressures

2005 ◽  
Vol 475-479 ◽  
pp. 1333-1336 ◽  
Author(s):  
Jan Ji Sha ◽  
J.S. Park ◽  
Tatsuya Hinoki ◽  
Akira Kohyama ◽  
J. Yu
Keyword(s):  
Oxygen Partial Pressure ◽  
Partial Pressure ◽  
Tensile Properties ◽  
Creep Behavior ◽  
Elevated Temperatures ◽  
Low Oxygen ◽  
X Ray Diffraction ◽  
Sic Fibers ◽  
Partial Pressures ◽  
Ar Gas

Three kinds of atmospheres (air, highly-pure Ar and ultra highly-pure Ar gas) with different oxygen partial pressures were applied to investigate the tensile properties and creep behavior of SiC fibers such as Hi-NicalonTM and TyrannoTM-SA. These fibers were annealed and crept at elevated temperatures ranging from1273-1773 K in such environments. After annealing at 1773 K, the room temperature tensile strengths of SiC-based fibers decreased with decreasing the oxygen partial pressure and the near stoichiometric fiber TyrannoTM-SA shows excellent strength retention. At temperatures above the 1573 K, the creep resistance of SiC fibers evaluated by bending stress relaxation (BSR) method under high oxygen partial pressure was lower than that of in low oxygen partial pressure. The microstructural features on these fibers were examined by scanning electron microscopy (SEM) and X-ray diffraction (XRD).

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