Energy Reduction in a Divided Wall Distillation Column

The paper presents the analysis of the thermal efficiency of a dividing wall distillation column and the influence of the feed composition on the reduction of energy consumption compared to a classical scheme of multicomponent mixture separation. The study relays on rigorous simulations in HYSYSTM using thermodynamically equivalent schemes. A case study is presented for the separation of a hydrocarbon mixture: benzene, toluene, ethylbenzene, o-xylene separated in three products in a dividing wall column. The dividing wall column solution led to about 40 % energy saving. The efficiency of a dividing wall column increases when the middle component is in large amount in the feed.

"Val Verde on the Sunny Rio Grande" Geoarcheological and Historical Investigations at San Felipe Springs, Val Verde County, Texas

In the fall of 1997, Prewitt and Associates, Inc. conducted archival and oral history research, an archeological survey, and National Register testing of a prehistoric site in the vicinity of the San Felipe Springs in southeastern Val Verde County, Texas. The work was done in preparation for construction of a water treatment plant and related facilities for the City of Del Rio. The survey resulted in the recording of one historic site (41VV1820) and further documentation of historic and prehistoric components at a previously known site, 41VV444. The latter site also was the focus of intensive geoarcheological investigations. National Register testing of 41VV444, called the San Felipe Springs site, was restricted to portions of the alluvial terraces of San Felipe Creek near the East and West San Felipe Springs. A 40-m' block excavation near the East Springs revealed three stratified prehistoric components in the upper ca. 100 m of alluvium. These sediments represent continual deposition over the last 3,000-4,000 years, and archeological materials denoting Late Prehistoric, Protohistoric, Late Archaic, and Middle Archaic occupations were recovered. The upper component post-dates A.D. 1300 and produced plain bone-tempered potsherds, ClifIton and Perdiz arrow points, and steeply beveled scrapers. This component represents a Toyah phase occupation on the western periphery of the Toyah culture area, but it shares many attributes with Protohistoric Infierno phase occupations of the Lower Pecos. The middle component is characterized by Shumla dart points and three pit features originating near the base of a dense burned rock layer. It represents utilization of the area during the Flanders Subperiod of the Late Archaic. Although recovered from many sites (particularly rockshelters), the chronology of Shumla points is not well established in the region. Radiocarbon assays place the age of the San Felipe Springs Shumla component at ca. 800-200 B.C. Geomorphic evidence suggests that a major flood episode (or episodes) occurred along San Felipe Creek between ca. 1300 and 800 B.C. This gravelly deposit separates the middle component from the lower component and is indicative of a high volume flood event, possibly similar to the August 1998 flooding along San Felipe Creek resulting from Hurricane Charley. Underlying this zone is a discrete Middle Archaic occupation containing a dense burned rock layer and an internal pit feature. Radiocarbon dates, along with associated Bulverde and Langtry variant dart points, correlate to the San Felipe Subperiod. Also associated with this occupation is a small concentration of artifacts representing a dump or cache of usable lithic materials. Historic components at 41VV1820 and 41VV444 contain structures related to the City of Del Rio's water pumping and distribution system. These resources, particularly the East Springs pump house and pond enclosure at 41VV444, are historically significant; however, they will be removed during construction of new water pumping facilities. Site 41VV444 encompasses most of what is now the San Felipe Country Club golf course. Built by Texas' first golf course architect, John Bredemus, in 1922, the San Felipe course is now recognized as an important historic landscape.