Pressurized Fluidized-bed Coal Combustion Research Articles

Capture of SO2 by limestone in a 71 MWe pressurized fluidized bed boiler

A 71 MWe pressurized fluidized bed coal combustor was operated. A wide variety of coals were burnt under fly ash recycle conditions. Limestone was fed to the combustor as bed material as well as sorbent. The emission of SO^ and limestone attrition rate were measured. A simple mathematical model of SO? capture by limestone with intermittent solid attrition was applied to the analysis of the present experimental results. Except for high sulfur fuel, the results of the present model agreed with the experimental results.

00/02866 Oxidation reaction of calcium sulfide in an advanced PFBC [pressurized fluidized-bed coal combustion] condition. Effects of O 2 concentration, type of limestone and particle size

00/02866 Oxidation reaction of calcium sulfide in an advanced PFBC [pressurized fluidized-bed coal combustion] condition. Effects of O 2 concentration, type of limestone and particle size

99/00403 Oxidation of calcium sulfide in an advanced PFBC (pressurized fluidized-bed coal combustion) cycle—effect of O 2 concentration and particle size on CaS oxidation

99/00403 Oxidation of calcium sulfide in an advanced PFBC (pressurized fluidized-bed coal combustion) cycle—effect of O 2 concentration and particle size on CaS oxidation

98/03797 Possibilities of utilizing solid residues from pressurized fluidized bed coal combustion (PSBC) for the production of blended cements

98/03797 Possibilities of utilizing solid residues from pressurized fluidized bed coal combustion (PSBC) for the production of blended cements

Influence of coal type on evolution characteristics of alkali metal compounds in coal combustion

The influence of coal type on the evolution characteristics of alkali metal compounds, especially sodium compounds, on the supposition of pressurized fluidized-bed coal combustion was elucidated experimentally in this study by using a rapidly heated electrical batch reactor. The evolution fraction of sodium was evaluated quantitatively by analyzing the sodium content in the burnt particles. Water and ammonium acetate extractions were carried out to classify the form of sodium compounds in the raw coals, and the ion components in the water-extracted solution were also analyzed by ion chromatography. Additionally, the relation between the existing locations of sodium and other elements at the cross section in the particle of raw coals was analyzed by an energy-dispersive X-ray (EDX) system and was quantified by means of the cross-correlation method between the locations of two elements. The results show that the evolution characteristics of sodium are influenced by the coal composition/structure. The water-soluble sodium was the largest fraction in all of the coals tested. Most of the sodium evolved was classified as water-soluble sodium. From the results of the cation and anion components in the water-extracted solution, the sodium in the coals with sodium chloride as a major sodium compound was evolved more easily than that in other coals. The distributions of sodium, silicon, and aluminum contributed to the evolution characteristics of sodium. The coals with high cross-correlation coefficients between sodium and silicon/aluminum had a low evolution fraction of sodium.

97/04862 Effect of pressure on the combustion characteristics in a pressurized fluidized-bed coal combustor: Song, B.-H. et al. Hwahok Konghak, 1996, 34, (5), 619–628. (In Korean)

97/04862 Effect of pressure on the combustion characteristics in a pressurized fluidized-bed coal combustor: Song, B.-H. et al. Hwahok Konghak, 1996, 34, (5), 619–628. (In Korean)

Thermodynamics of the Na2SO4-K2SO4-CoSO4 system and their relevance to low-temperature hot corrosion

Thermodynamic calculations and experiments were performed to determine the SO3 partial pressures and temperatures at which K2SO4-CoSO4 binary mixed liquid phases form on CoO and Co3O4 in the presence of K2SO4. The calculations and experiments are in excellent agreement. Similar calculations were also made of the compositions at the liquidus surface and the associated SO3 partial pressures for the K2SO4-Na2SO4-CoSO4 ternary system. These calculations show that the presence of K2SO4 substantially reduces the SO3 partial pressures required to stabilize a liquid salt phase on the surface of oxidized cobalt alloys at 600–800°C. Consequently, at these temperatures the hot corrosion in coal-fired systems, where K levels are high, is expected to be worse than in oil-fired systems, where K levels are low. This prediction was confirmed by experiments in a pressurized fluidized bed coal combustor and in an atmospheric pressure burner rig.

Bubble Characterization in Pressurized Fluidized-Bed Combustors with Bed Internals

Abstract Bubble Characterization in Pressurized Fluidized-Bed Combustors with Bed Internals Abstract–Bubble characteristics within a tube bundle of a Pressurized Fluidized Bed Coal Combustor (PFBC) were studied. A model was developed to compute emulsion phase gas velocity, bubble throughflow velocity, and the visible bubble flow coefficient. Experimental data obtained from a PFBC unit were compared with the model prediction and a good agreement was observed.

Size distribution of particulate emissions from a pressurized fluidized bed coal combustion facility

Particle size distribution measurements were conducted on the emissions from the pressurized fluidized bed coal combustion test facility at the British National Coal Board, Coal Utilization Research Laboratory, Leatherhead England during September 1979. The particle size samples were taken on stream 1 downstream of the third stage cyclone and upstream of the cascade of turbine blades supplied by Stal Laval. The particle size distribution measurements were performed using an 11 stage Mark 5 University of Washington Source Test Cascade Impactor. The mass median aerodynamic particle diameter of the 14 size distribution tests ranged from about 1.6 to 3.4 μm with an average of around 2.5 μm. The geometric standard deviation of the log-normal approximation of the particle size distributions ranged from 2.3 to 3.6. The particle size distributions were very nearly log-normal in shape with the correlation coefficients between the actual and log-normal approximation ranging from 0.98 to 0.998 with an average of 0.992. The particle mass concentrations ranged from 0.39 to 0.69gm −3 at actual conditions (or 0.11 to 0.21 gm −3 at standard conditions)

Volatilization/Condensation of Alkali Salts in a Pressurized Fluidized Bed Coal Combustor/Gas Turbine Combined Cycle

Thermochemical models are used to predict the behavior of sodium and potassium contaminants in a pressurized fluidized bed coal combustor (PFBC)/gas turbine (GT) combined cycle. The alkalis, originating from the coal and dolomite (or limestone) in the bed, exist in the combustion gases primarily as their chlorides. They subsequently condense in the gas turbine as sulfates. The amounts of sulfates deposited may be about two orders of magnitude higher than those normally encountered in oil‐fired gas turbines. The results of our calculations compare well with the few experimental data available at present.

Evaluation of a cyclone dust collector for high-temperature, high-pressure particulate control

The performance of conventional cyclones operating at temperatures up to 900 C and pressures up to 900 kPa on flue gas from a pressurized fluidized bed coal combustion unit was measured. The cyclones were very efficient, generally removing particulates to a level of 0,04 to 0.7 g/m/sub 3/ at the exit of a three-stage cyclone system. Cyclone performance was measured using a total filter/Coulter Counter technique and cascade impactor to measure the particulate size distribution. The two methods gave comparable results.