Effect of Suspended Particles on Crystallization Fouling in Plate Heat Exchangers

Bansal, Bipan; Müller‐Steinhagen, Hans; Chen, X. D.

doi:10.1115/1.2824143

Cited by 58 publications

(23 citation statements)

References 7 publications

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“…The proposed composite model predicts the initial fouling rate for the un ltered runs to be 5 times that of ltered runs. This value is in relatively good agreement with the ratio of 2.7 to 3.3 determined by Hasson and Zahavi [1] and the ratio of 3 by Bansal et al [6]. The difference between the ratio predicted by this composite model and the experimental results of Hasson and Zahavi [1] and Bansal et al [6] can be due to the absence of the removal term in the model that might be of signi cance for CaSO 4 , which is more susceptible to removal than a strongly adherent CaCO 3 scale.…”

Section: Resultssupporting

confidence: 79%

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Calcium Sulfate Fouling-Precipitation or Particulate: A Proposed Composite Model

Sheikholeslami¹

2000

Heat Transfer Engineering

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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 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 4 fouling. In this article, a new model is proposed for CaSO 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 4 tends to weaken its crystalline structure and makes it more prone than CaCO 3 to removal. Properties of the electrolyte were evaluated using MINTEQA2 computer code, which is approved by the U.S. 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 ow and deposit properties. The inclusion of both crystallization and removal terms incorporates the effects of both water chemistry and hydrodynamics of the ow 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 predictions: the slope of predicted rates as a function of the experimental rates is 1.05. The experimental results, though limited in number, suggest that crystallization is not the main or only mechanism contributing to CaSO 4 fouling. Particulate fouling seems to be a major contributor. Further experimentation is in process to con rm the degree of particulate fouling and to substantiate or to modify the model accordingly.

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Section: Resultssupporting

confidence: 79%

“…Particulate fouling has been the subject of various investigation s [6,7,11,16,20]. Most recently, McGarvey et al [21] showed experimentally the synergistic effects of particulate fouling in the presence of scale formation (or crystallizatio n fouling ).…”

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confidence: 99%

Calcium Sulfate Fouling-Precipitation or Particulate: A Proposed Composite Model

Sheikholeslami¹

2000

Heat Transfer Engineering

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“…However, the structure of the fouled layer depends on the type of particulate material; particulates might either both reduce the tenacity and increase the porosity of the fouled layer or only increase the tenacity of the fouled layer. A study was recently done to investigate the effect of crystallizing and non-crystallizing particles in fouling of heat exchangers with supersaturated salts; the results show that the type of particulate material has a pronounced effect on the fouling behavior [24].…”

Section: Composite Inorganic and Biological Foulingmentioning

confidence: 99%

“…Various theories and models have been proposed to explain and predict the behavior and extent of particulate fouling in process equipments [21][22][23]. Recently the effect of crystallizing and non-crystallizing particles have also been studied [24] that shows the former augment fouling while the latter hinder fouling. Deposits from pure crystallization are usually hard and tenacious while the deposits in particulate fouling can be porous and susceptible to removal.…”

Section: Inorganic Foulingmentioning

confidence: 99%

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Composite fouling ‐ inorganic and biological: A review

Sheikholeslami

1999

Environ. Prog.

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Recent research on fouling in desalination systems, cooling towers, ocean thermal energy conversion (OTEC) heat exchangers, salinity power plants (SPP), etc. where composite inorganic and biological fouling may be present is reviewed. Crystallization or precipitation fouling is the most studied type of fouling. Other types of fouling are studied in various degrees of detail in isolation. In practical industrial applications, usually several types of fouling occur simultaneously, not in isolation. However, not much attention has been paid to the relative significance and the interactive effects of these processes when they occur simultaneously. This is specifically the case for composite inorganic and biological fouling. In general, there is complete lack of attention to the presence, mechanism, modeling and mitigation of composite fouling.

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