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Title: Calcium sulfate fouling -- Precipitation or particulate: A proposed composite model

Abstract

Though it is of great importance, the majority of predictive models tend not to incorporate water chemistry in their formulations. The ionic diffusion model which was developed for CaCO{sub 3}, is based purely on crystallization, and is one of the few models that incorporates water chemistry. This model does not provide satisfactory predictions for CaSO{sub 4} fouling. In this article, a new model is proposed for CaSO{sub 4} fouling which takes into account the effect of both crystallization and particulate fouling and is capable of predicting the fouling resistance during the cleaning cycle as well as the fouling cycle. A removal term is incorporated into the model, as the occurrence of particulate fouling for CaSO{sub 4} tends to weaken its crystalline structure and makes it more prone than CaCO{sub 3} to removal. Properties of the electrolyte were evaluated using MINTEQA2 computer code, which is approved by the US Environmental Protection Agency. In this model, particulate fouling is estimated using the physical mechanism for particle transport and adherence, crystallization is estimated by ionic diffusion, and the removal term is approximated using hydrodynamics of flow and deposit properties. The inclusion of both crystallization and removal terms incorporates the effects of both watermore » chemistry and hydrodynamics of the flow and provides a relationship which not only can predict fouling but also can predict dissolution, by change of water quality and/or stopping the operation, or removal by shear stress. The proposed model was assessed using published experimental data. The results indicate that this model provides good prediction. The experimental results, though limited in number, suggest that crystallization is not the main or only mechanism contributing to CaSO{sub 4} fouling. Particulate fouling seems to be a major contributor.« less

Authors:
Publication Date:
Research Org.:
Univ. of New South Wales, Sydney (AU)
OSTI Identifier:
20075626
Resource Type:
Journal Article
Journal Name:
Heat Transfer Engineering
Additional Journal Information:
Journal Volume: 21; Journal Issue: 3; Other Information: PBD: May-Jun 2000; Journal ID: ISSN 0145-7632
Country of Publication:
United States
Language:
English
Subject:
32 ENERGY CONSERVATION, CONSUMPTION, AND UTILIZATION; 02 PETROLEUM; HEAT EXCHANGERS; FOULING; CALCIUM SULFATES; PRECIPITATION; PARTICULATES; M CODES; MATHEMATICAL MODELS; CRYSTALLIZATION

Citation Formats

Sheikholeslami, R. Calcium sulfate fouling -- Precipitation or particulate: A proposed composite model. United States: N. p., 2000. Web. doi:10.1080/014576300270870.
Sheikholeslami, R. Calcium sulfate fouling -- Precipitation or particulate: A proposed composite model. United States. doi:10.1080/014576300270870.
Sheikholeslami, R. Thu . "Calcium sulfate fouling -- Precipitation or particulate: A proposed composite model". United States. doi:10.1080/014576300270870.
@article{osti_20075626,
title = {Calcium sulfate fouling -- Precipitation or particulate: A proposed composite model},
author = {Sheikholeslami, R.},
abstractNote = {Though it is of great importance, the majority of predictive models tend not to incorporate water chemistry in their formulations. The ionic diffusion model which was developed for CaCO{sub 3}, is based purely on crystallization, and is one of the few models that incorporates water chemistry. This model does not provide satisfactory predictions for CaSO{sub 4} fouling. In this article, a new model is proposed for CaSO{sub 4} fouling which takes into account the effect of both crystallization and particulate fouling and is capable of predicting the fouling resistance during the cleaning cycle as well as the fouling cycle. A removal term is incorporated into the model, as the occurrence of particulate fouling for CaSO{sub 4} tends to weaken its crystalline structure and makes it more prone than CaCO{sub 3} to removal. Properties of the electrolyte were evaluated using MINTEQA2 computer code, which is approved by the US Environmental Protection Agency. In this model, particulate fouling is estimated using the physical mechanism for particle transport and adherence, crystallization is estimated by ionic diffusion, and the removal term is approximated using hydrodynamics of flow and deposit properties. The inclusion of both crystallization and removal terms incorporates the effects of both water chemistry and hydrodynamics of the flow and provides a relationship which not only can predict fouling but also can predict dissolution, by change of water quality and/or stopping the operation, or removal by shear stress. The proposed model was assessed using published experimental data. The results indicate that this model provides good prediction. The experimental results, though limited in number, suggest that crystallization is not the main or only mechanism contributing to CaSO{sub 4} fouling. Particulate fouling seems to be a major contributor.},
doi = {10.1080/014576300270870},
journal = {Heat Transfer Engineering},
issn = {0145-7632},
number = 3,
volume = 21,
place = {United States},
year = {2000},
month = {6}
}