Modeling the SO<sub>2</sub>‐slurry droplet reaction

Newton, G.H.; Kramlich, John C.; Payne, R.

doi:10.1002/aic.690361210

Cited by 49 publications

(22 citation statements)

References 8 publications

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“…The decrease of Ca utilization with the stoichiometric ratio is because the S capture efficiency increases less than linearly with Ca/S ratio. 11,12 Figures 6 and 7 report the overall plant performance, that is, the total SO 2 removal efficiency and Ca conversion degree after the spray dryer plus baghouse. Experimental data show that an additional 5-10% SO 2 removal is achieved in the baghouse, corresponding to a 5-10%…”

Section: Resultsmentioning

confidence: 99%

“…where n SO2 11,12 A decrease of the flue gas inlet temperature or of the approach to adiabatic saturation temperature leads to a slower evaporation rate, thus providing extended droplet lifetime for SO 2 absorption. As regards Ca utilization, figures show that a larger utilization is achieved at a lower Ca/S ratio, inlet gas temperature, and ⌬T AS .…”

Section: Resultsmentioning

confidence: 99%

“…Additional options to enhance the performance of the spray dryer have been reported. 7,[11][12][13]22 These rely on an accurate control of the average size of lime particles dispersed in the slurry and of the atomization characteristics (drop size). The size of dispersed lime particles depends on the lime slaking process and on the properties of the parent quicklime.…”

Section: Resultsmentioning

confidence: 99%

“…Mechanistic models have been proposed by Karlsson and Klingspor, 10 Harriott, 16 Partridge et al, 13 and Hill and Zank. 11 A more detailed model was proposed by Newton et al, 12 who devoted particular attention to the microscopic behavior of the single droplets. The calculation relied, however, on a time-consuming trial-and-error procedure in which, at each step, the reaction front position in the droplet had to be checked.…”

Section: Introductionmentioning

confidence: 99%

“…7,[11][12][13] In general, higher overall SO 2 removal efficiencies are obtained by slowing down the evaporation rate (e.g., by approaching the adiabatic saturation temperature at the dryer outlet) and by enhancing the SO 2 mass-transfer rate (e.g., by increasing the calcium [Ca]-to-S feed ratio or by decreasing the average size of lime particles dispersed in the slurry).…”

Section: Introductionmentioning

confidence: 99%

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Spray-Dry Desulfurization of Flue Gas from Heavy Oil Combustion

Scala

Lancia

Nigro

et al. 2005

Journal of the Air & Waste Management Association

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An experimental investigation on sulfur dioxide removal in a pilot-scale spray dryer from the flue gas generated by combustion of low-sulfur (S) heavy oil is reported. A limewater slurry was sprayed through an ultrasonic two-fluid atomizer in the spray-dry chamber, and the spent sorbent was collected downstream in a pulse-jet baghouse together with fly ash. Flue gas was sampled at different points to measure the desulfurization efficiency after both the spray-dry chamber and the baghouse. Parametric tests were performed to study the effect of the following variables: gas inlet temperature, difference between gas outlet temperature and adiabatic saturation temperature, lime-to-S ratio, and average size of lime particles in the slurry.Results indicated that spray drying is an effective technology for the desulfurization of low-S fuel oil flue gas, provided operating conditions are chosen carefully.In particular, the lowest gas inlet and outlet temperatures compatible with baghouse operation should be selected, as should a sufficiently high lime-to-S ratio. The attainment of a small lime particle size in the slurry is critical for obtaining a high desulfurization efficiency.A previously presented spray-dry flue gas desulfurization model was used to simulate the pilot-scale desulfurization tests, to check the ability of the model to predict the S capture data and its usefulness as a design tool, minimizing the need for pilot-scale experimentation.Comparison between model and experimental results was fairly good for the whole range of calcium/S ratios considered.

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Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Spray-Dry Desulfurization of Flue Gas from Heavy Oil Combustion

Scala

Lancia

Nigro

et al. 2005

Journal of the Air & Waste Management Association

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Model for flue‐gas desulfurization in a circulating dry scrubber

Neathery

1996

AIChE Journal

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A simple model was developed to describe the absorption of SO, in a circulating d y scrubbing (CDS) process, which is a semidy, lime-based, flue-gas desulfurization (FGD) process that utilizes a circulating fluidized bed arrangement for contucting a sorbent with SO, -laden flue gas under "coo1side"conditions. The reaction chemisty is thought to be similar to that of spray-dying absolption. The liquid-phase mass-transfer coeficient was successfully modeled as a function of the sorbent particle spacing on the wetted surfaces. Gas-phase mass-transfer resistances were assumed to be insignificant. Due to the high surface area available in a CDS reactor, the evaporation rate of water @om the slury was modeled as "constant-rate "dying according to classic spray-dryer theory. However, the "falling-rate 'jand "difision "evaporation stages were negligible in CDS since sorbent particle bunching at the surface of the sluny is nonexistent. IntroductionWet flue-gas desulfurization (FGD) processes were the first SO, control systems to be developed on a commercial scale in the United States. These systems were initially plagued by reliability problems due to a combination of the early status of development at the time, poor design, and questionable operating procedures. In addition, most electric utility plant operators had no previous experience with "chemical plant" operation. By the late 1980s, most of these problems were overcome and some technological advances were made in the scrubbing area that improved wet FGD reliability. However, wet FGD systems remain costly to operate due to large work force requirements, the generation of large quantities of solid waste by-products that must be disposed, and high parasitic energy requirements.Wet scrubber systems are characterized by high liquid-togas ratios (L/G) of liquid sorbent slurry to flue gas. The L/G ratios, ranging from 5,400 to 13,400 1 Nm-3 (40 to 100 gal/std. kft3), are high enough to completely saturate the treated flue gas with water vapor. Typically, some untreated flue gas is bypassed around the scrubber modules to reheat the scrubbed gas and prevent troublesome condensation in the duct and stack.Because of the many shortcomings with wet FGD systems, the power utility industry is continually seeking new processes that will lower the capital, operating, and disposal costs associated with these conventional SO, control systems. in the early 1980s, pilot studies of semidry FGD processes, such as spray-drying absorption, were conducted to determine their potential as SO, control technologies. Many semidry FGD technologies have reached commercial scale in the last decade. As a result, a large number of studies have been performed to research and further develop these processes.As a contrast to wet FGD systems, semidry systems operate with low L/G ratios (about 28 to 40 1 Nm-3 or 0.2 to 0.3 gal/std. kft3) as compared to 5,400 to 13,400 1 Nm-3 or 40 to 100 gal/kSCF or higher for wet FGD systems). Since massive slurry pipe circuits and the associated pumps are not require...

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