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Title: Alkali-metal-vapor removal from pressurized fluidized-bed combustor flue gas. Annual report, October 1980-September 1981

Abstract

This work supports the program to develop methods for the cleanup of high-temperature, high-pressure combustion gases from pressurized fluidized-bed coal combustors so that the cleaned gases can be used to power downstream gas turbines. Data are presented in this report on the use of activated bauxite in a granular bed filter for the removal of gaseous NaCl from hot (800/sup 0/C), pressurized (less than or equal to 8 atm), wet simulated PFBC flue gas. Also, the sorption mechanisms are discussed. Greater than 99.9% NaCl vapor capture was achieved. Also reported are (1) the effects of several operating variables on the rate of leaching of NaCl that had been adsorbed on activated bauxite and (2) the volatility of alkali metal compounds present as impurities in activated bauxite. Finally, the preliminary estimate of the cost of using activated bauxite as a filter medium for the control of alkali vapors from PFBC flue gas was updated; a conceptual design of a fixed granular-bed filter was presented; and the energy needs and their costs for operating the filter in (a) the once-through and (b) the sorbent-regeneration modes were compared.

Authors:
;
Publication Date:
Research Org.:
Argonne National Lab., IL (USA)
OSTI Identifier:
5599666
Report Number(s):
ANL/FE-81-59
ON: DE82008088
DOE Contract Number:
W-31-109-ENG-38
Resource Type:
Technical Report
Country of Publication:
United States
Language:
English
Subject:
01 COAL, LIGNITE, AND PEAT; 20 FOSSIL-FUELED POWER PLANTS; 42 ENGINEERING; ALKALI METALS; REMOVAL; BAUXITE; CHEMICAL REACTIONS; HEAT TREATMENTS; PURIFICATION; FLUE GAS; HOT GAS CLEANUP; GRANULAR BED FILTERS; DESIGN; PERFORMANCE; COST; SODIUM CHLORIDES; COAL; CORROSION; FLUIDIZED-BED COMBUSTION; GAS TURBINES; MEDIUM PRESSURE; MICROSTRUCTURE; POROSITY; REGENERATION; SORPTIVE PROPERTIES; VAPORS; ALKALI METAL COMPOUNDS; ALUMINIUM ORES; CARBONACEOUS MATERIALS; CHLORIDES; CHLORINE COMPOUNDS; COMBUSTION; CRYSTAL STRUCTURE; ELEMENTS; ENERGY SOURCES; FILTERS; FLUIDS; FOSSIL FUELS; FUELS; GASEOUS WASTES; GASES; HALIDES; HALOGEN COMPOUNDS; MACHINERY; MATERIALS; MECHANICAL FILTERS; METALS; ORES; OXIDATION; SODIUM COMPOUNDS; SURFACE PROPERTIES; THERMOCHEMICAL PROCESSES; TURBINES; TURBOMACHINERY; WASTES; 010800* - Coal, Lignite, & Peat- Waste Management; 014000 - Coal, Lignite, & Peat- Combustion; 200202 - Fossil-Fueled Power Plants- Waste Management- Noxious Gas & Particulate Emissions; 421000 - Engineering- Combustion Systems

Citation Formats

Johnson, I., and Lee, S.H.D. Alkali-metal-vapor removal from pressurized fluidized-bed combustor flue gas. Annual report, October 1980-September 1981. United States: N. p., 1982. Web.
Johnson, I., & Lee, S.H.D. Alkali-metal-vapor removal from pressurized fluidized-bed combustor flue gas. Annual report, October 1980-September 1981. United States.
Johnson, I., and Lee, S.H.D. 1982. "Alkali-metal-vapor removal from pressurized fluidized-bed combustor flue gas. Annual report, October 1980-September 1981". United States. doi:.
@article{osti_5599666,
title = {Alkali-metal-vapor removal from pressurized fluidized-bed combustor flue gas. Annual report, October 1980-September 1981},
author = {Johnson, I. and Lee, S.H.D.},
abstractNote = {This work supports the program to develop methods for the cleanup of high-temperature, high-pressure combustion gases from pressurized fluidized-bed coal combustors so that the cleaned gases can be used to power downstream gas turbines. Data are presented in this report on the use of activated bauxite in a granular bed filter for the removal of gaseous NaCl from hot (800/sup 0/C), pressurized (less than or equal to 8 atm), wet simulated PFBC flue gas. Also, the sorption mechanisms are discussed. Greater than 99.9% NaCl vapor capture was achieved. Also reported are (1) the effects of several operating variables on the rate of leaching of NaCl that had been adsorbed on activated bauxite and (2) the volatility of alkali metal compounds present as impurities in activated bauxite. Finally, the preliminary estimate of the cost of using activated bauxite as a filter medium for the control of alkali vapors from PFBC flue gas was updated; a conceptual design of a fixed granular-bed filter was presented; and the energy needs and their costs for operating the filter in (a) the once-through and (b) the sorbent-regeneration modes were compared.},
doi = {},
journal = {},
number = ,
volume = ,
place = {United States},
year = 1982,
month = 1
}

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  • This work supports the program to develop sorbents for the cleanup of gases from pressurized fluidized-bed coal combustion (PFBC) so that the cleaned hot gases can be used to power downstream gas turbines without causing corrosion. A simulated PFBC flue gas containing NaCl vapor was used to characterize activated bauxite and diatomaceous earth at a bed temperature of 905/sup 0/C and a system pressure of 10 atm absolute. The NaCl vapor was found to be captured by activated bauxite essentially as sodium sulfate, with a small fraction captured as sodium chloride. In contrast, diatomaceous earth captured NaCl vapor by amore » combined result of (1) a chemical reaction that converts the vapor into condensed sodium sulfate and (2) chemical reactions that transform the captured sodium into water-insoluble silicate compounds. In NaCl-vapor sorption efficiency studies, a 12.7-cm-long activated bauxite bed was tested for 12 h in a gas stream containing 4 to 8 ppmV NaCl-vapor concentration, and >99.8% NaCl-vapor sorption efficiency was achieved. This efficiency compared with 99.1 and 95.3% obtained by a diatomaceous earth bed of the same length tested for 8 h in gas streams containing 28 and 2 ppmV NaCl-vapor concentration, respectively. The addition of HCl to the simulated flue gas had an insignificant effect on the NaCl-vapor sorption behavior and efficiency of activated bauxite. Experimental results are also presented on (1) the water leachability of the sodium captured on activated bauxite, (2) the partial conversion to sodium sulfate of the NaCl sample used as the vapor source for the sorption tests, and (3) the changes in the chemical and physical properties of both sorbents as a result of exposure to the simulated flue gas.« less
  • In the application of pressurized fluidized-bed combustion (PFBC) to the generation of electricity, hot corrosion of the gas turbine (downstream from the combustor) by alkali metal compounds is a potential problem. The objective of this investigation is to develop a method for the removal of gaseous alkali metal compounds from the high-pressure high-temperature gas from a PFBC before the gas enters the gas turbine. The use of a granular bed filter, with either diatomaceous earth or activated bauxite as the bed material, is under study. Breakthrough data are reported on the sorption of gaseous NaCl by activated bauxite. Results aremore » reported for the regeneration of activated bauxite using water leaching and a thermal swing method.« less
  • Under the auspices of US Department of Energy, this work supports the program to develop sorbents for the cleanup of gases from pressurized fluidized-bed coal combustion (PFBC) so that these cleaned hot gases can be used to power downstream gas turbines without causing corrosion. A laboratory-scale pressurized test unit was used to continue the alkali-vapor characterization of activated bauxite and Emathlite at a bed temperature of 850/sup 0/C and a system pressure of 10 atm absolute in a simulated PFBC flue gas stream containing <10 ppMV NaCl vapor. Under the test conditions, preliminary results show a comparable NaCl-vapor capture capabilitymore » for both activated bauxite and Emathlite. Emathlite was found to capture NaCl vapor essentially by chemical reactions with the vapor to form water-insoluble compounds, probably sodium aluminosilicates, whereas activated bauxite captures the vapor mainly by physical adsorption as sodium sulfate. The test unit was modified and tested to improve the control of NaCl vaporization in the unit required for the source of alkali vapor in the simulated flue gas. Experimental results are also presented on (1) water leachability of both metallic and nonmetallic ions present in activated bauxite when it is cyclically heat-treated in a simulated PFBC flue gas environment and then leached with distilled water, and (2) the effect of heat-treatment of Emathlite in the simulated PFBC flue gas on the changes of its physical and chemical properties.« less
  • Under the auspices of the US Department of Energy, this work supports a program to develop sorbents for the cleanup of alkali corrodents from the flue gas produced by pressurized fluidized-bed coal combustion (PFBC) so that the cleaned hot gas is able to power downstream gas turbines without causing corrosion. This effort for FY 1984 involved two parts. In the first part, a laboratory-scale pressurized test unit was used to measure the rate of alkali (Na + K) evolution from beds of activated bauxite and Emathlite at a bed temperature of 850/sup 0/C and a system pressure of 10 atmmore » absolute in a gas stream closely simulating the actual PFBC flue gas. The evaluation of the measured rates showed that (1) a spent activated bauxite bed, regenerated by water leaching and replenished with a small amount of fresh activated bauxite, contributes significantly less alkali vapor to the flue gas than the currently accepted alkali tolerance (0.024 ppM) of an industrial gas turbine and (2) the Emathlite bed contributes more alkali vapor than the turbine tolerance limit if the bed is exposed to a flue gas for a space time greater than 0.5 seconds. In the second part, a laboratory-scale demonstration of a fixed granular-bed sorber for the control of alkali vapor from PFBC flue gas was initiated. A detailed engineering design of this sorber system is described, and initial test results are presented and discussed. 26 refs., 16 figs.; 14 tabs.« less
  • A laboratory-scale pressurized fluidized-bed coal combustor (PFBC)/alkali sorber was used (1) to measure the alkali vapor (Na and K) concentration in PFBC flue gas on a real-time on-line basis, and (2) to demonstrate simultaneously the granular-bed sorber concept for the removal of alkali vapors from hot PFBC flue gas. An Ames alkali analyzer was used as an on-line, real-time monitor. A batch-type alkali and particulate sampling train (APST) was also installed as a backup for the analysis of both alkali vapor and particulate loading in the flue gas. The test results showed that the particulate loading in the flue gasmore » which exited from the tertiary cyclone varied from 150 to 350 ppMW. The alkali vapor concentration measured by the Ames alkali analyzer was <10 ppBW, which is 1 to 2 orders of magnitude greater than that measured by the batch-type APST. However, consideration of the analytical uncertainty of the two measuring techniques indicated that the difference may not be as great as observed. The analysis of the alkali contents in fly ash samples suggested a negligible evolution of potassium in coal during combustion; however, a significant evolution of sodium was indicated. In a series of laboratory tests, heated (>700/sup 0/C) stainless steel tubing was shown to capture NaCl vapor. This observation suggested that the stainless steel tubing and parts used in the flue gas sampling line of the PFBC/alkali sorber facility could be a sink for the sodium vapor. Further study is needed to verify this postulation. 22 refs., 7 tabs., 15 figs.« less