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Title: A fixed granular-bed sorber for measurement and control of alkali vapors in PFBC (pressurized fluidized-bed combustion)

Abstract

Alkali vapors (Na and K) in the hot flue gas from the pressurized fluidized-bed combustion (PFBC) of coal could cause corrosion problems with the gas turbine blades. In a laboratory-scale PFBC test with Beulah lignite, a fixed granular bed of activated bauxite sorbent was used to demonstrate its capability for measuring and controlling alkali vapors in the PFBC flue gas. The Beulah lignite was combusted in a bed of Tymochtee dolomite at bed temperatures ranging from 850 to 875{degrees}C and a system pressure of 9.2 atm absolute. The time-averaged concentration of sodium vapor in the PFBC flue gas was determined from the analysis of two identical beds of activated bauxite and found to be 1.42 and 1.50 ppmW. The potassium vapor concentration was determined to be 0.10 ppmW. The sodium material balance showed that only 0.24% of the total sodium in the lignite was released as vapor species in the PFBC flue gas. This results in an average of 1.56 ppmW alkali vapors in the PFBC flue gas. This average is more than 1.5 orders of magnitude greater than the currently suggested alkali specification limit of 0.024 ppm for an industrial gas turbine. The adsorption data obtained with the activatedmore » bauxite beds were also analyzed mathematically by use of a LUB (length of unused bed)/equilibrium section concept. Analytical results showed that the length of the bed, L{sub o} in centimeters, relates to the break through time, {theta}{sub b} in hours, for the alkali vapor to break through the bed as follows: L{sub o} = 33.02 + 1.99 {theta}{sub b}. This formula provides useful information for the engineering design of fixed-bed activated bauxite sorbers for the measurement and control of alkali vapors in PFBC flue gas. 26 refs., 4 figs., 4 tabs.« less

Authors:
;
Publication Date:
Research Org.:
Argonne National Lab., IL (USA)
Sponsoring Org.:
DOE/FE
OSTI Identifier:
6154760
Report Number(s):
ANL/CP-71607; CONF-910424-1
ON: DE91004439
DOE Contract Number:
W-31109-ENG-38
Resource Type:
Conference
Resource Relation:
Conference: 11. international conference on fluidized bed combustion, Montreal (Canada), 21-24 Apr 1991
Country of Publication:
United States
Language:
English
Subject:
01 COAL, LIGNITE, AND PEAT; FLUIDIZED-BED COMBUSTORS; GRANULAR BED FILTERS; PERFORMANCE; POTASSIUM; ADSORPTION; SODIUM; BAUXITE; CHEMICAL PROPERTIES; CLEANING; COAL-FIRED GAS TURBINES; CORROSION; DIMENSIONS; DOLOMITE; EROSION; EXHAUST GASES; FLOWSHEETS; FLUIDIZED-BED COMBUSTION; LIGNITE; MATERIAL BALANCE; MATHEMATICAL MODELS; PRESSURIZATION; REMOVAL; SORPTIVE PROPERTIES; TIME DEPENDENCE; TURBINE BLADES; VAPORS; ALKALI METALS; ALKALINE EARTH METAL COMPOUNDS; ALUMINIUM ORES; BROWN COAL; CALCIUM CARBONATES; CALCIUM COMPOUNDS; CARBON COMPOUNDS; CARBONACEOUS MATERIALS; CARBONATE MINERALS; CARBONATES; CHEMICAL REACTIONS; COAL; COMBUSTION; COMBUSTORS; DIAGRAMS; ELEMENTS; ENERGY SOURCES; FILTERS; FLUIDS; FOSSIL FUELS; FUELS; GAS TURBINES; GASEOUS WASTES; GASES; MACHINERY; MAGNESIUM CARBONATES; MAGNESIUM COMPOUNDS; MATERIALS; MECHANICAL FILTERS; METALS; MINERALS; ORES; OXIDATION; OXYGEN COMPOUNDS; SORPTION; SURFACE PROPERTIES; THERMOCHEMICAL PROCESSES; TURBINES; TURBOMACHINERY; WASTES; 010402* - Coal, Lignite, & Peat- Purification & Upgrading

Citation Formats

Lee, S.H.D., and Swift, W.M. A fixed granular-bed sorber for measurement and control of alkali vapors in PFBC (pressurized fluidized-bed combustion). United States: N. p., 1990. Web.
Lee, S.H.D., & Swift, W.M. A fixed granular-bed sorber for measurement and control of alkali vapors in PFBC (pressurized fluidized-bed combustion). United States.
Lee, S.H.D., and Swift, W.M. Mon . "A fixed granular-bed sorber for measurement and control of alkali vapors in PFBC (pressurized fluidized-bed combustion)". United States. doi:. https://www.osti.gov/servlets/purl/6154760.
@article{osti_6154760,
title = {A fixed granular-bed sorber for measurement and control of alkali vapors in PFBC (pressurized fluidized-bed combustion)},
author = {Lee, S.H.D. and Swift, W.M.},
abstractNote = {Alkali vapors (Na and K) in the hot flue gas from the pressurized fluidized-bed combustion (PFBC) of coal could cause corrosion problems with the gas turbine blades. In a laboratory-scale PFBC test with Beulah lignite, a fixed granular bed of activated bauxite sorbent was used to demonstrate its capability for measuring and controlling alkali vapors in the PFBC flue gas. The Beulah lignite was combusted in a bed of Tymochtee dolomite at bed temperatures ranging from 850 to 875{degrees}C and a system pressure of 9.2 atm absolute. The time-averaged concentration of sodium vapor in the PFBC flue gas was determined from the analysis of two identical beds of activated bauxite and found to be 1.42 and 1.50 ppmW. The potassium vapor concentration was determined to be 0.10 ppmW. The sodium material balance showed that only 0.24% of the total sodium in the lignite was released as vapor species in the PFBC flue gas. This results in an average of 1.56 ppmW alkali vapors in the PFBC flue gas. This average is more than 1.5 orders of magnitude greater than the currently suggested alkali specification limit of 0.024 ppm for an industrial gas turbine. The adsorption data obtained with the activated bauxite beds were also analyzed mathematically by use of a LUB (length of unused bed)/equilibrium section concept. Analytical results showed that the length of the bed, L{sub o} in centimeters, relates to the break through time, {theta}{sub b} in hours, for the alkali vapor to break through the bed as follows: L{sub o} = 33.02 + 1.99 {theta}{sub b}. This formula provides useful information for the engineering design of fixed-bed activated bauxite sorbers for the measurement and control of alkali vapors in PFBC flue gas. 26 refs., 4 figs., 4 tabs.},
doi = {},
journal = {},
number = ,
volume = ,
place = {United States},
year = {Mon Jan 01 00:00:00 EST 1990},
month = {Mon Jan 01 00:00:00 EST 1990}
}

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  • A fixed granular-bed sorber is being developed at Argonne National Laboratory (ANL) for the control of the alkali vapor in a PFBC process stream. To achieve the objectives of this project, a high-temperature, high-pressure alkali sorber has been designed, fabricated, and installed onto the ANL laboratory-scale 15.2-cm-dia (6-in.-dia) pressurized fluidized-bed combustion (PFBC) facility (PFBC/alkali sorber facility). The real-time alkali concentrations (sodium and potassium) in the process stream are measured by an Ames on-line alkali analyzer for both the sorber-inlet and sorbed-outlet gas streams. In addition to the Ames alkali analyzer, a batch-type alkali and particulate sampling train (APST) is installedmore » as a back-up for the analysis of both alkali vapor and particulate in the sorber-inlet gas stream. The APST is designed on the basis of a cold-trap condensation method. Three experimental activities have been proceeding during this year: (1) laboratory calibration of the Ames alkali analyzer and the batch-type APST, (2) laboratory study on alkali-vapor capture by stainless steel, and (3) modification of the PFBC/alkali sorber to reduce particulate loading in the PFBC process stream. Results of each activity are presented in this report.« less
  • Alkali-metal compounds, such as chlorides and sulfates of sodium and potassium, present in the flue gas of coal combustion could cause hot corrosion of a gas turbine. The current industrial gas-turbine specification limit for alkali-metal compounds in the combustion gas entering a turbine is equivalent to 0.024 ppmW. Spacil and Luthra predict that the quantity of alkali vapor in the flue gas from PFBC could be up to two orders of magnitude greater than this allowable level. In contrast, the recent calculations by Scandrett and Clift suggest that, if the aerosol alkali particulate could be removed, the residual alkali vapormore » in the flue gas would be less than the limit. Measurements of the alkali vapor in PFBC flue gas have been made by several institutions. The measured alkali vapor concentration in the flue gas is in the order of 0.1 to 10 ppmW. Normally, a conventional batch-type extraction of the flue gas, followed by the analysis of the condensate, has been used in these measurements. It was not until recently that a real-time, on-line alkali analyzer was developed and tested in the gas stream of both coal gasification and combustion. A fixed granular-bed sorber is being developed at Argonne National Laboratory (ANL) for the control of the alkali vapor in PFBC flue gas. After an extensive screening study, activated bauxite was found to be the most effective sorbent in capturing the NaCl, KCl, and K/sub 2/SO/sub 4/ vapors that were doped into a simulated PFBC flue gas. Activated bauxite was also demonstrated to be easily and effectively regenerated for reuse by a simple water-leaching process. A capture efficiency of greater than 99.8% CaCl vapor has been achieved. The effectiveness of activated bauxite for alkali-vapor capture has been confirmed by others. 21 refs., 12 figs., 5 tabs.« less
  • This work supports a program to measure the level of alkali vapors in the flue gas from the pressurized fluidized-bed combustion (PFBC) of coal and to develop a granular-bed sorber system for their control. A laboratory-scale fixed granular-bed sorber (7.9-cm-dia) was constructed and integrated with a 15.2-cm-dia (6-in.-dia) PFB combustor system for the alkali vapor measurement and evaluation of the sorber unit. Tests were conducted with Sewickley coal and Tymochtee dolomite at bed temperatures from 875 to 950/sup 0/C and a system pressure of 9 atm absolute. The alkali concentrations, sodium and potassium, in the filtered hot (850 to 900/supmore » 0/C) flue gas streams were measured with an Ames on-line real-time alkali analyzer and found to be <10 ppbW. An alkali concentration 1-2 orders of magnitude greater was determined in tests on a batch-type alkali sampling train. Alkali analysis of the fly ash suggests a negligible evolution of potassium from coal; however, a much higher sodium evolution from coal than the measured concentrations is indicated. Laboratory studies demonstrated the capture of NaCl vapor by heated (>750/sup 0/C) stainless steel, indicating that the stainless steel material used in the PFBC/alkali sorber system could act as a sink for alkali vapors. Details of the tests are presented and the results are discussed. 18 refs., 10 figs., 7 tabs.« less
  • Studies have been conducted to develop a fixed granular-bed sorber for the removal of alkali vapors in a pressurized fluidized-bed combustion (PFBC) combinedcycle system. A laboratory-scale pressurized alkalivapor sorption test unit was used to characterize activated bauxite, the most effective sorbent identified earlier, for its alkali vapor sorption capability in a gas stream with temperature (less than or equal to900/sup 0/C), pressure (10 atm absolute), and composition closely simulating the actual PFBC flue gas. A scale-up of laboratory tests is being conducted in a 15.2-cm-dia (6-in.-dia) PFBC system to demonstrate the granular-bed sorber concept. The NaCl-vapor sorption chemistry of activatedmore » bauxite is described. The extent of alkalivapor evolution from the activated bauxite bed itself is discussed, along with an evaluation of the significance of its alkali vapor contribution to a downstream gas turbine. Details of the design of a high-temperature/high-pressure alkali sorber system for the demonstration of the sorber are presented.« less
  • Studies have been conducted to develop a fixed granular-bed sorber for the removal of alkali vapors in a pressurized fluidized-bed combustion (PFBC) combined-cycle system. A laboratory-scale pressurized alkali vapor sorption test unit was used to characterize activated bauxite, the most effective sorbent identified earlier, for its alkali vapor sorption capability in a gas stream with temperature (less than or equal to 900/sup 0/C), pressure (10 atm absolute), and composition closely simulating the actual PFBC flue gas. A scale-up of laboratory tests is being conducted in a 15.2-cm-dia (6-in.-dia) PFBC system to demonstrate the granular-bed sorber concept. The NaCl-vapor sorption chemistrymore » of activated bauxite is described. The extent of alkali-vapor evolution from the activated bauxite bed itself is discussed, along with an evaluation of the significance of its alkali vapor contribution to a downstream gas turbine. Details of the design of a high-temperature/high-pressure alkali sorber system for the demonstration of the sorber are presented. 15 references, 6 figures, 3 tables.« less