Preliminary Results of Testing of Flow Effects on Evaporator Scaling

PDF Version Also Available for Download.

Description

This investigation has focused on the effects of fluid flow on solids deposition from solutions that simulate the feed to the 2H evaporator at the Savannah River Site. Literature studies indicate that the fluid flow (or shear) affects particle-particle and particle-surface interactions and thus the phenomena of particle aggregation in solution and particle deposition (i.e., scale formation) onto solid surfaces. Experimental tests were conducted with two configurations: (1) using a rheometer to provide controlled shear conditions and (2) using controlled flow of reactive solution through samples of stainless steel tubing. All tests were conducted at 80 C and at high ... continued below

Physical Description

34 pages

Creation Information

Hu, M.Z. February 15, 2002.

Context

This report is part of the collection entitled: Office of Scientific & Technical Information Technical Reports and was provided by UNT Libraries Government Documents Department to Digital Library, a digital repository hosted by the UNT Libraries. More information about this report can be viewed below.

Who

People and organizations associated with either the creation of this report or its content.

Author

Sponsor

Publisher

Provided By

UNT Libraries Government Documents Department

Serving as both a federal and a state depository library, the UNT Libraries Government Documents Department maintains millions of items in a variety of formats. The department is a member of the FDLP Content Partnerships Program and an Affiliated Archive of the National Archives.

Contact Us

What

Descriptive information to help identify this report. Follow the links below to find similar items on the Digital Library.

Description

This investigation has focused on the effects of fluid flow on solids deposition from solutions that simulate the feed to the 2H evaporator at the Savannah River Site. Literature studies indicate that the fluid flow (or shear) affects particle-particle and particle-surface interactions and thus the phenomena of particle aggregation in solution and particle deposition (i.e., scale formation) onto solid surfaces. Experimental tests were conducted with two configurations: (1) using a rheometer to provide controlled shear conditions and (2) using controlled flow of reactive solution through samples of stainless steel tubing. All tests were conducted at 80 C and at high silicon and aluminum concentrations, 0.133 M each, in solutions containing 4 M sodium hydroxide and 1 A4 each of sodium nitrate and sodium nitrite. Two findings from these experiments are important for consideration in developing approaches for reducing or eliminating evaporator scaling problems: (1) The rheometer tests suggested that for the conditions studied, maximum solids deposition occurs at a moderate shear rate, approximately 12 s{sup -1}. That value is expected to be on the order of shear rates that will occur in various parts of the evaporator system; for instance, a 6 gal/min single-phase liquid flow through the 2-in. lift or gravity drain lines would result in a shear rate of approximately 16 s{sup -1}. These results imply that engineering approaches aimed at reducing deposits through increased mixing would need to generate shear near all surfaces significantly greater than 12 s{sup -1}. However, further testing is needed to set a target value for shear that is applicable to evaporator operation. This is because the measured trend is not statistically significant at the 95% confidence interval due to variability in the results. In addition, testing at higher temperatures and lower concentrations of aluminum and silicon would more accurately represent conditions in the evaporator. Without further testing, it does not appear advisable to depend on increased agitation as the primary means for reduction of scale in the 2H, evaporator. (2) The tubes used in the flow tests became clogged with solids when the solutions were below 80 C at the start of the test; a very striking difference from experiments with fully preheated solutions, which yielded only thin films of solids on the tubes. These results suggest that significant differences are found in the ''stickiness'' of solids formed at different temperatures. This may provide opportunities for engineering approaches to reduce solids deposition, such as feed dispersion or feed preheating. It is recommended that further studies be undertaken to determine what forms of sodium aluminosilicates adhere to stainless steel surfaces, under what conditions these materials are created, and what changes in evaporator operation could be made to minimize their formation.

Physical Description

34 pages

Source

  • Other Information: PBD: 15 Feb 2002

Language

Item Type

Identifier

Unique identifying numbers for this report in the Digital Library or other systems.

  • Report No.: ORNL/TM-2001/235
  • Grant Number: AC05-00OR22725
  • DOI: 10.2172/814197 | External Link
  • Office of Scientific & Technical Information Report Number: 814197
  • Archival Resource Key: ark:/67531/metadc734606

Collections

This report is part of the following collection of related materials.

Office of Scientific & Technical Information Technical Reports

Reports, articles and other documents harvested from the Office of Scientific and Technical Information.

Office of Scientific and Technical Information (OSTI) is the Department of Energy (DOE) office that collects, preserves, and disseminates DOE-sponsored research and development (R&D) results that are the outcomes of R&D projects or other funded activities at DOE labs and facilities nationwide and grantees at universities and other institutions.

What responsibilities do I have when using this report?

When

Dates and time periods associated with this report.

Creation Date

  • February 15, 2002

Added to The UNT Digital Library

  • Oct. 18, 2015, 6:40 p.m.

Description Last Updated

  • March 31, 2016, 1:12 p.m.

Usage Statistics

When was this report last used?

Yesterday: 0
Past 30 days: 0
Total Uses: 8

Interact With This Report

Here are some suggestions for what to do next.

Start Reading

PDF Version Also Available for Download.

International Image Interoperability Framework

IIF Logo

We support the IIIF Presentation API

Hu, M.Z. Preliminary Results of Testing of Flow Effects on Evaporator Scaling, report, February 15, 2002; United States. (digital.library.unt.edu/ark:/67531/metadc734606/: accessed October 17, 2018), University of North Texas Libraries, Digital Library, digital.library.unt.edu; crediting UNT Libraries Government Documents Department.