Effect of relative humidity and additives on the reaction of sulfur dioxide with calcium hydroxide

Thesis/Dissertation · Wed Jan 01 04:00:00 EST 1986

OSTI ID:6829541

Ruiz-Alsop, R N

The objective of this research was to investigate the effect of process variables and additives on the reaction rate of Ca(OH)/sub 2/ with SO/sub 2/ at conditions similar to these encountered in the bag filters used to collect solids following flue gas desulfurization by spray drying. The effect of Ca(OH)/sub 2/ loading, temperature, relative humidity, and inlet SO/sub 2/ concentration were investigated. Of these variables, relative humidity showed the greatest impact on the reaction rate. The effect of small amounts of additives were also investigated. Of the additives tried (buffer acids, organic deliquescents, and inorganic deliquescents) deliquescent salts were the only additives that improved reactivity. A shrinking core model with zero order kinetics in SO/sub 2/ was used to model experimental data. An empirical correlation was included in the model to account for shape and surface roughness of the Ca(OH)/sub 2/ particles. The diffusion coefficient of the SO/sub 2/ through the product layer was found to increase linearly with relative humidity, and the kinetic rate constant increases exponentially with relative humidity. With a few exceptions the model was able to predict the experimental data within the margin of experimental error (+/- 10%). At high relative humidity and/or high SO/sub 2/ concentration, reaction kinetics control the overall reaction rate, while at low relative humidity and/or low SO/sub 2/ concentration, SO/sub 2/ diffusion through the product layer controls the rate. The reaction solids were characterized by scanning electron microscopy, powder x-ray diffraction, Coulter counter size distribution BET (N/sub 2/) surface area, energy dispersive spectrometry, and differential scanning calorimetry.

• Research Organization: Texas Univ., Austin (USA)
• OSTI ID: 6829541
• Country of Publication: United States
• Language: English

Related Subjects

01 COAL, LIGNITE, AND PEAT
010800* -- Coal
Lignite
& Peat-- Waste Management
ADDITIVES
ALKALINE EARTH METAL COMPOUNDS
BAGHOUSES
CALCIUM COMPOUNDS
CALCIUM HYDROXIDES
CALCIUM SULFATES
CALORIMETRY
CATALYTIC EFFECTS
CHALCOGENIDES
CHEMICAL REACTION KINETICS
CHEMICAL REACTIONS
COHERENT SCATTERING
DESULFURIZATION
DIFFRACTION
DIFFUSION
ELECTRON MICROSCOPY
EQUIPMENT
FLUE GAS
GASEOUS WASTES
HUMIDITY
HYDROGEN COMPOUNDS
HYDROXIDES
KINETICS
MATHEMATICAL MODELS
MICROSCOPY
OXIDES
OXYGEN COMPOUNDS
PARTICLE SIZE CLASSIFIERS
POLLUTION CONTROL EQUIPMENT
QUANTITY RATIO
REACTION KINETICS
SCANNING ELECTRON MICROSCOPY
SCATTERING
SPECTROSCOPY
SULFATES
SULFUR COMPOUNDS
SULFUR DIOXIDE
SULFUR OXIDES
SURFACE AREA
SURFACE PROPERTIES
TEMPERATURE DEPENDENCE
WASTES
X-RAY DIFFRACTION