SummaryDuring this quarter, work has finally resumed on the black liquor volubility experiments (Task A. 1), but no new data have yet been generated. The crystallization experiments with inorganic model solutions (Task B. 1) have been completed, and crystallization experiments with kraft black liquor (Task B.2) have been started. The Annular Test Cell (ATC) apparatus is now fully operational, while construction of the falling film evaporator pilot plant (Task C. 1) is nearly complete. Startup of this unit is planned for late in Quarter 6. In the CFD model development work (Task D.2), the relaxation of simpli~ing assumptions in the falling film model have been completed, and expressions were developed to estimate film velocity/tihn Reynolds number relations. Also, thin film data taken for a range of conventional fluids were compared to predictions using selected methods, and attempts were initiated to extrapolate to approximate black liquor evaporator conditions.

SummaryThe quarterly project review meeting was held at IPST on August 2, 1999 and was attended by IPST, Georgia Tech, and ORNL principal investigators, members of the Industrial Advisory Group, and a U.S. DOE representative. Although steady progress is being made, this project is currently behind schedule. The specific tasks that are behind schedule, the reasons for the delays, and the expected completion dates are discussed in the Performance Variances and Open Items section below. The remaining tasks are either on schedule, or have not been started. Performance Variances and Open ItemsTask A. 1, Solubilitv ex~eriments -one kraft black liauor (scheduled completion date: 6/99), and Task A.2, Solubilitv data obtained -other liauors (scheduled completion date: 9/99). Both of these tasks are behind schedule due to needed modifications in the equipment and procedures (described in the Quarter 3 report), and to our technician being unavailable because of an extended illness. We have regained our technical support and added a part time technician. Our plan is to complete Task A. 1 in Quarter 6, and Task A.2 by the end of Quarter 7.Task B. 1, Crystallization ex~eriments -inorzanic model solutions (scheduled completion date: 9/99). This task is behind schedule because of delays in obtaining finding to buy the Lasentec@ FBRM 600L system. We expect this task to be completed by the end of the current quarter (December 1999).Task C. 1, Pilot falling film eva~orator operational (scheduled completion date: 9/99). This task is behind schedule due to slower than expected progress in installing the piIot evaporators. We expect to compIete the pilot falling film evaporator installation by the end of the current quarter (December 1999), and to have it operational in Quarter 6. Task D. 1.3, Relax simnlifiin~assum~tions (scheduled completion date: 7/99), and Task D. 1.4, Com~are to experimental results: tweliminarv analvsis (scheduled completion date: 9/99). These two tasks are behind schedule because of the change in personnel at ORNL that was described in the Quarter 3 report. We anticipate completing Task D. 1.3 by the end of the current quarter (December 1999), and Task D. 1.4 in Quarter 6. Status of Progress by TaskA. 1. Volubility experiments -one kraft black liquor. Scheduled completion date: 6/99. Current status: in progress. Progress during the quarter:The modifications to the equipment and the operating procedures, which were described in the Quarter 3 report, have been completed. However, no new experimental work has been performed. Progress during the quarter: A series of experiments have been carried out to study the effect of black liquor content on the metastable zone width of the inorganic model solutions. Black liquor was added at one percent into the solution, and the results showed that the metastable zone width of Burkeite decreased when compared to black liquor free solutions.Equipment to study the secondary nucleation kinetics of the model solution has been installed and preliminary experiments with this new e...