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Chilled Brine Separation

Description:

TECHNOLOGY AREA(S): Materials 

OBJECTIVE: Develop a capability to separate Dynalene HC-40 and Ethylene glycol/water mixture while retaining at least 90% of the original concentration of the corrosion inhibitors from the ethylene glycol in the process. 

DESCRIPTION: The goal is to develop a system capable of separating the Dynalene HC-40 and ethylene glycol while retaining at least 90% of the original concentration of the corrosion inhibitors in the ethylene glycol. The fluids Dynalene HC-40 and ethylene glycol/water are used as brines for industrial refrigeration processes. The two brines are contained in a shell and tube heat exchanger with the Dynalene HC-40 on the tube side and the ethylene/glycol water mixture on the shell side. The ethylene glycol is normally only exposed to air and the Dynalene HC-40 is normally only exposed to nitrogen and becomes corrosive when in contact with air. Under normal circumstances the ethylene glycol and Dynalene HC-40 are kept separate. However in the large Air Force test facilities, there are conditions under which portions of the two fluids become mixed and must be separated. Information from the vendor of Dynalene HC-40 indicates an ethylene glycol mixture with a Dynalene concentration as little as 5% by weight can make the mixture become corrosive when exposed to air. Furthermore, the ethylene glycol system includes a glycol concentrator that removes water from solution. When Dynalene HC-40 enters the concentrator, a portion of the Dynalene HC-40 is left on the heat transfer surfaces of the concentrator decreasing the effectiveness of the concentrator. Thus, a capability is needed to extract on average one gallon per hour of Dynalene HC-40 from a 14,000 gallon ethylene glycol/water solution originally containing 5% Dynalene HC-40 by weight. The final Dynalene concentration in the ethylene/glycol water mixture needs to be less than 1% by weight. The temperature of the ethylene/glycol Dynalene HC-40 solution can vary widely, ranging from -24 °F to 90 °F. The ethylene glycol is manufactured by KOST USA under the product name Kostchill HD 100 and contains a borate/nitrite type corrosion inhibitor package. The Dynalene HC-40 is manufactured by Dynalene Inc. and contains a proprietary inhibitor package. At least 90% of the original concentration of the borate/nitrite corrosion inhibitor in the ethylene glycol must be present after the separation process. The retention of the Dynalene HC-40 is not a requirement for this effort. After separation, the ethylene glycol needs to be returned to an active ethylene glycol system and the Dynalene HC-40 discharged to a proper container for storage and disposal. 

PHASE I: Demonstrate the feasibility of separating the Dynalene HC-40 and ethylene glycol/water mixture with the separated ethylene glycol retaining at least 90% of the original concentration of the borate/nitrite type corrosion inhibitor. Establish and demonstrate a small scale process capable of separating the Dynalene HC-40 and ethylene glycol/water mixture resulting in a final Dynalene concentration in the ethylene/glycol water mixture of less than 0.5% by weight. 

PHASE II: Develop and demonstrate a prototype system capable of extracting on average one gallon per hour of Dynalene HC-40 from an ethylene glycol/water solution containing 5% Dynalene HC-40 by weight. The final Dynalene concentration in the ethylene/glycol water mixture should be less than 1% by weight. The final ethylene glycol product needs to retain at least 90% of the original concentration of the borate/nitrite type corrosion inhibitor. 

PHASE III: The proposed process would be applicable to military or commercial facilities using large quantities of ethylene glycol to reduce the need to purchase new ethylene glycol each time it becomes contaminated with a corrosive substance such as Dynalene HC-40. 

REFERENCES: 

1: "Dynalene HC Heat Transfer Fluid Engineering Guide," https://www.dynalene.com/v/vspfiles/templates/210/datasheets/Dynalene_HC_Engineering_guide.pdf

2:  "Kostchill HD 100 Product Data Sheet," https://www.kostusa.com/page/safety-data-sheets

KEYWORDS: Brine, Separation, Corrosion 

CONTACT(S): 

Jimmy Steele 

(931) 454-3739 

jimmy.steele.5@us.af.mil 

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