F-AREA PUMP TANK 1 MIXING ANALYSIS

[摘要] The F-area pump tanks are used to transfer supernate, sludge, and other materials. In any transfer, the solution must stay well mixed without allowing particulate matter to settle out of the liquid and, thus, accumulate in the bottom of the pump tank. Recently, the pulse jet mixing in F-area Pump Tank 1 (FPT1) has been decommissioned. An analysis of the liquid transfer through FPT1 has been performed using computational fluid dynamics (CFD) methods to assess whether or not the velocities throughout the tank will remain high enough to keep all particulate suspended using only transfer and recirculation pumps. The following paragraph is an abbreviated synopsis of the transfer procedure for FPT1 [1, 2]. Prior to a transfer, FPT1 begins to be filled with inhibited water through the inlet transfer line (TI). When the tank liquid level reaches 52.5 inches above the absolute tank bottom, the recirculation pump (RI and RO) is activated. At a tank liquid level of 72.5 inches above the absolute tank bottom, the outlet transfer line (TO) is activated to reduce the liquid level in FPT1 and transfer inhibited water to H-area Pump Tank 7 (HPT7). The liquid level is reduced down to 39.5 inches, with an allowable range from 37.5 to 41.5 inches above the absolute tank bottom. HPT7 goes through a similar procedure as FPT1 until both have tank liquid levels of approximately 39.5 inches above the absolute tank bottom. The transfer of inhibited water continues until a steady-state has been reached in both pump tanks. At this point, the supernate/sludge transfer begins with a minimum flow rate of 70 gpm and an average flow rate of 150 gpm. After the transfer is complete, the pump tanks (both FPT1 and HPT7) are pumped down to between 20.5 and 22.5 inches (above absolute bottom) and then flushed with 25,000 gallons of inhibited water to remove any possible sludge heal. After the flushing, the pump tanks are emptied. Note that the tank liquid level is measured using diptubes. Figure 2.1 provides a simplified sketch (not to scale) of FPT1 during the steady-state transfer condition, which consists of two inlet flows that impact the liquid surface as plunging jets and two outlet flows drawn from near the bottom of the tank. During the transfer, the supernate level is held at 39.5 inches above the absolute bottom of the tank [1, 2]. In addition, the FPT1 can contain up to 16.7 wt.% sludge particles within the supernate for a given transfer [2]. Test results from Tank 40 sludge Batch 3 [3] provide a typical range of particulate diameters between 0.1 and 25 {micro}m, with approximately 20 vol.% of the sludge distribution consisting of particles less than 1 {micro}m in diameter. The purpose of this analysis is to estimate FPT1 flow field during the steady-state transfer conditions to ensure that the tank remains mixed and that the velocities throughout the tank are sufficient to keep all sludge particulate suspended.

[发布日期] 2008-11-05

[学科分类] 核能源与工程

[关键词] AR FACILITIES;FLUID MECHANICS;LIQUID WASTES;PUMPING;MIXING;SLURRIES;MATERIALS HANDLING;TANKS;OPERATION;RADIOACTIVE WASTES