Industrial-scale demonstration of a new sorbent reactivation technology for fluidized bed combustors

Anthony, Edward J.; McCleave, Robert; Gandolfi, E. A. J.; Wang, Jinsheng

doi:10.1016/s0301-4797(03)00144-0

Cited by 13 publications

(5 citation statements)

References 11 publications

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“…With regard to the effectiveness of using hydrated ash as a SO 2 sorbent in fluidized bed combustors, tests were carried out with a FBC pilot plant and a 35 MW utility boiler. ,, The pilot plant study showed that, at the same molar ratio of calcium to sulfur, the ash performed at least as well as the limestone . In the test with the utility boiler, ash hydrated by wet grinding was mixed with coal fines and injected into the boiler along with limestone.…”

Section: Resultsmentioning

confidence: 99%

The Hydration Behavior of Partially Sulfated Fluidized Bed Combustor Sorbent

Wang

Anthony

2005

Ind. Eng. Chem. Res.

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The efficiency of limestone sorbent utilization in fluidized bed combustors (FBCs) is low, because of incomplete sulfation of CaO. Hydration of the FBC ash can reactivate the partially sulfated sorbent, and the hydrated ash can be reinjected into the combustors as the SO2 sorbent. In this work, the rate of hydration, which is of primary importance in the reactivation process, is studied for FBC ash. The effects of major rate factors, temperature and particle size, are analyzed. At ambient temperature, the degree of hydration is well below 100% after 4 h of testing, suggesting the existence of a barrier to the complete conversion of CaO. The particle size effect on hydration rate appears to be complex, but can be interpreted in terms of the effects of heat and mass transfer. A model is proposed that gives a consistent description of the hydration behavior, and methods for enhancing the hydration are discussed.

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Section: Resultsmentioning

confidence: 99%

The Hydration Behavior of Partially Sulfated Fluidized Bed Combustor Sorbent

Wang

Anthony

2005

Ind. Eng. Chem. Res.

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“…A batch of ash from the same boiler, reactivated by the above-described procedure, was added to the coal feed hopper. The details have been reported elsewhere …”

Section: Resultsmentioning

confidence: 99%

“…The details have been reported elsewhere. 34 Therefore, a higher feed rate was required from the coal bin to produce the same steam flow rate. A variable heating load in the University also changed the boiler load.…”

Section: Purdue Ashmentioning

confidence: 99%

Advanced Fluidized Bed Combustion Sorbent Reactivation Technology

Anthony

MacKenzie

Trass

et al. 2003

Ind. Eng. Chem. Res.

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A new technique for simultaneous grinding and hydrating of fluidized bed combustion (FBC) bottom ash has been developed. This method has been shown to be effective in hydrating the CaO component of the ash, so that the sorbent is reactivated. Careful control of water levels is required to prevent energy demand increases for grinding. No problems associated with the potentially exothermic reaction of water with FBC bottom ash have been observed during grinding. When excess water (over that required by hydration) is used, the resulting material is a slurry and, while quantitative conversion of CaO in the solids is achieved, using the slurry for the sorbent would require a redesign of the limestone feed system. Therefore, coal or unreacted ash is added to the mixture after grinding. The resulting dry product contains the spent bed material in a completely hydrated form. The reactivated ash produced has been evaluated for sulfur capture using thermogravimetric analysis and a CFBC pilot plant. Conversion rates of almost 100% are achieved for ash after grinding hydration. An industrial demonstration of the technology has supported its viability with no decrease in sulfur capture, while limestone requirements decreased by 18%. The economic implications of the industrial applicability of the technology are outlined in a case study using the Point Aconi CFBC unit. Decreased limestone usage is calculated to net savings in the order of $500000/year. The project is calculated to have an equity payback of less than 1 year.

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“…Reactivation by water hydration of industrial FBC ashes generates, besides Ca(OH) 2 , several calcium silico/sulpho/aluminate hydrates, like ettringite29–31; the formation of these binding phases, which can be exploited for further desulfurization, may on the other hand adversely influence the operation of regenerators by promoting agglomeration of hydrated particles. Careful design and operation of the regenerator is, therefore, required to overcome operational issues 32. Conversely, the formation of a dry product and the limited fraction of binding phases after steam reactivation of spent FBC ashes makes it possible to overcome agglomeration.…”

Section: Introductionmentioning

confidence: 99%

Steam reactivation of a spent sorbent for enhanced SO₂ capture in FBC

et al. 2006

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The regeneration by steam hydration of the sulfur capture ability of spent sorbent particles from Fluidized Bed Combustion (FBC) is addressed. The process is characterized in terms of effectiveness of sorbent reactivation, hydration degree, particle sulfation pattern, development of accessible porosity, and extent of particle attrition and fragmentation. Steam reactivation experiments were carried out in a lab-scale atmospheric FBC at 250 degrees C for 10, 30, and 180 min with 0.05 MPa steam partial pressure. The effectiveness of sorbent reactivation was assessed by reinjecting the reactivated material into the FB reactor operated at 850 degrees C under simulated desulfurization conditions and following the degree of calcium conversion and the attrition rate along with resulfation. The experimental results indicated that steam reactivation is effective in renewing the SO2 uptake ability of the exhausted sorbent particles. The regeneration mechanism based on the swelling upon hydration of the unreacted core, the generation of fissures and cracks, and the consequent development of accessible porosity is confirmed for the limestone under scrutiny. In addition to this, a remarkable result was that steam hydration induces, for the sorbent under investigation, a pronounced sulfur redistribution throughout the particle cross-section, which provides another pathway to the enhancement of the sulfur capture ability of the reactivated sorbent. (c) 2006 American Institute of Chemical Engineers

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Industrial-scale demonstration of a new sorbent reactivation technology for fluidized bed combustors

Cited by 13 publications

References 11 publications

The Hydration Behavior of Partially Sulfated Fluidized Bed Combustor Sorbent

The Hydration Behavior of Partially Sulfated Fluidized Bed Combustor Sorbent

Advanced Fluidized Bed Combustion Sorbent Reactivation Technology

Steam reactivation of a spent sorbent for enhanced SO₂ capture in FBC

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Industrial-scale demonstration of a new sorbent reactivation technology for fluidized bed combustors

Cited by 13 publications

References 11 publications

The Hydration Behavior of Partially Sulfated Fluidized Bed Combustor Sorbent

The Hydration Behavior of Partially Sulfated Fluidized Bed Combustor Sorbent

Advanced Fluidized Bed Combustion Sorbent Reactivation Technology

Steam reactivation of a spent sorbent for enhanced SO2 capture in FBC

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Product

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Steam reactivation of a spent sorbent for enhanced SO₂ capture in FBC