Concentration of Evaporator Concentrates - NUKEM Technologies

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The solutions collected in the recycling tank during the first stage of the evaporation or during flushing the evaporator are transferred to the UGU-feed tank. These solutions are processed together with the next batch of evaporator concentrates. Once the operating temperature has been reached, operation of the facility occurs almost automatically. During the concentration process, some deposits settle on the internal walls of the evaporator pipes. After a time, these deposits slow down the facility processing rate. This undesirable situation is automatically detected and the control unit switches the facility into flushing mode. The flushing of the one-pass evaporator with recycled distillate cleans the piping. After the cleaning cycles the evaporator concentrates are once again fed to the evaporator. CD-1000 Concentrate Dryer (CD) Systems (see Fig.: 6 Concentrate-Dryer) utilize a low temperature, vacuum based, high agitation, batch-drying approach to remove the water in liquid waste streams. This maximizes the volume reduction of water- based waste streams by converting the waste to a dry product consisting of the solids content of the feed stream. Examples of target waste streams include: • Evaporator bottoms, • Membrane concentrates, • Sump and tank sludge, • Non-dewaterable sludges, • Filtrates and resins, • Most water based solutions. The CD Systems will nominally process at their nameplate rating (e.g. CD-1000, CD-600, etc.) in gallons of concentrate slurry over a 24-hour cycle based upon 15% boric acid slurry. CD Systems remove virtually all the water from the waste by the use of an advanced internal waste blending and agitation process that directs the waste continually toward the center of the dryer, which transforms the waste into granules of uniform size. The first phase of the internal drying process brings the waste to a stage where large multisized “dough balls” have been formed. The next phase then breaks up these “dough balls” into small granular shapes that increase the waste surface area thus promoting faster drying. The waste product produced by CD Systems can be in either one of two different physical conditions. Both are final waste forms that are acceptable at disposal sites and are described below: Granules: Using this processing approach, the final waste product is a dry granular material. The volume reduction ratio is equivalent to the inverse of the weight percent of the solution (for example, if the weight percent of the solution is 20% or 0.20, then a 5:1 volume reduction is achieved). Salt Block Waste Form: In this processing approach the waste product is transferred to the container in a hot molasses-like condition which sets up in the container as a hard, dry, salt block when it cools. The salt block waste form can result in an additional volume reduction of as much as 40% beyond that offered by the granular NUKEM Technologies GmbH 2007 7
waste form. This processing approach is dependent on waste chemistry and was developed by NUKEM over twenty years of drying experience. Because of the density increase of the waste, the receiving High Integrity Container (HIC) must also have an adequate payload capability. To accommodate this, NUKEM has a specially certified 136 HIC to accept payloads up to 7250 kg. This HIC requires shipment in a larger size cask than a 10-142 due to cask payload restrictions. The dried waste products produced by CD Systems are routed through a gravity flow mechanism, which deposits the waste into the intended waste storage containers or disposal liner. This processing logic eliminates multiple handling and thus reduces cost and personnel radiation exposure. CD Systems are compatible with all types of waste containers, from drums to the largest High Integrity Containers (HIC’s). By removing the water from the waste stream slurry, internal space-wasting containers are no longer necessary. A complete utilization of the container’s internal usable volume is possible. CD Systems are comprised of the six modularized components listed below. System components are manufactured in various skidmounted modules for ease of movement and placement. For ALARA considerations, many of the components, such as the control panel, vacuum skid, chill water skid, and steam generator skid, can be remotely located in low background radiation areas. 1 Control Panel 2 The Dryer Unit 3 Steam Generator 4 Vacuum Skid 5 Chill Water System 6 Transfer Cart 8 NUKEM Technologies GmbH 2007
Page 1 and 2: Concentration of Evaporator Concent
Page 3 and 4: • first removal of some specific
Page 5 and 6: The vapours leaving the evaporator
Page 7: Fig. 5 One Way Evaporator UGU 6 NUK
Page 11 and 12: Technical Data Characteristics ROBE
Page 13 and 14: References Scope of supply Client P
Page 15 and 16: Fig. 2 ROBE Simplified Process Flow
Page 17 and 18: Fig. 4 UGU Simplified Process Flows
Page 19: www.nukemgroup.com

Concentration of Evaporator Concentrates - NUKEM Technologies

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