Precipitate hydrolysis experimental facility (PHEF) Run 66 And 67, Final report
During the period from late June to early September of this year, approximately 1,600 gallons of precipitate feed stored in the Precipitate Hold Tank (PHT) at PHEF decomposed. This decomposition took place during a two month storage period of the Tetraphenyl borate (TPB) precipitate under a CO{sub 2} blanket. The visual inspection of the tank revealed that a very small amount of TPB solids were left and that there were approximately 100 to 110 gals of benzene/high boilers present in the tank. The resultant decomposition products in the PHT consist of an organic and aqueous phase containing a small quantity of unreacted solids. A path forward was developed to understand TPB decomposition and to determine if the material remaining in the PHT could be processed without adverse effects to the process or equipment. A small scale hydrolysis run with the remaining PHT material was made by Process Technology Development Group of DWPT at TNX. It was determined from small scale runs and an extensive analysis of the PHT material that the decomposed material was safe to run at PHEF without adversely affecting the process or equipment. The PHT volume was 1,592 gallons at the time of decomposition. Two runs (66 and 67) were performed to process the decomposed feed. The main objective of these runs was to process the decomposed precipitate from the PHT. In both the runs copper nitrate was used as the catalyst. Because of the decomposition, the effectiveness of the copper nitrate in catalyzing the destruction of TPB could not be completed. The significant findings of Run 66 are: (1) after 5 hours of aqueous boil, the aqueous product had a Diphenylamine (DPA) concentration of 31 mg/L and the Biphenyl concentration of 8 mg/L. At these concentrations, the high boiling organic mass in the aqueous product included 0.28 lbs of Diphenylamine and 0.07 lbs of Biphenyl. (2) Benzene production was 62.1 gallons, with an aromatic removal ratio of 96.26% as measured by liquid chromatography analysis. (3) The calculated reactor cooling coil heat transfer coefficient during cooldown was 244 (design basis = 80) PCU/ft{sup 2}/hr/C at 55 C. It took 90 minutes to cooldown the reactor contents at cooling water flowrate of 20 gpm and 168 RPM agitator speed. This suggested that minimal high boilers deposition had occurred with the processing of decomposed feed. (4) Phenylboronic Acid concentration dropped below 53 mg/L in less than 180 minutes. As such very little PBA was produced because of the decomposed feed. The Organic Evaporator (OE) cycle was completed in two attempts. In the first attempt, the OE run was interrupted due to a high Evaporator Condenser Decanter (ECD) vapor temperature interlock, approximately 18 minutes into the aqueous boil (AB). The cause of this interlock was determined to be fouling of the ECD tubes by high boiling organics. Several process changes were implemented in an attempt to defoul the condenser tubes. The changes were mainly targeted at running the condenser hot. The increase in CW supply temperature and reduction in CW flow helped to run the condenser hot, to increase the heat transfer efficiency and to melt the high boiling organics from the condenser tubes.
- Research Organization:
- Savannah River Site (SRS), Aiken, SC (United States)
- Sponsoring Organization:
- US Department of Energy (US)
- DOE Contract Number:
- AC09-96SR18500
- OSTI ID:
- 751283
- Report Number(s):
- WSRC-RP-95-0044/Rev.0; TRN: US0103478
- Resource Relation:
- Other Information: Supercedes report DE00751283; PBD: 11 Feb 2000
- Country of Publication:
- United States
- Language:
- English
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