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Summers D.R.,Sulzer Chemtech United States Inc.
Chemical Engineering Progress | Year: 2010

The procedures that are used to design four-pass distillation column trays and to balance the vapor/liquid ratio on each tray panel are presented. The equal-bubbling-area (EBA) design method is the easiest to understand and use, but EBA trays may have the lowest capacity and slightly lower tray efficiency. An EBA tray has four flow passes with exactly the same active area and utilizes the same weir length for each pass. On any four-pass tray, the liquid and the vapor both split, with some of each flowing to one panel and some of each to other panel. The vapor splits and takes the path that equalizes the pressure drop and the liquid split is influenced by many factors. Another method, the equal-flowpath-length (EFPL) design method is more complicated than the EBA method, but it has the potential for higher tray efficiencies and higher capacities. The uniform flowpath in the EFPL designs enables the same amount of mass transfer on each tray panel, and the compositions in each of the downcomers of any tray will be the same. Source

Summers D.R.,Sulzer Chemtech United States Inc. | Monaco W.,Elekeiroz | Neiva M.A.,Elekeiroz
AIChE 2013 - 2013 AIChE Spring Meeting and 9th Global Congress on Process Safety, Conference Proceedings | Year: 2013

In 2004, the main distillation tower in the Oxo Alcohol Plant in South America was revamped. The tower experienced capacity limitations from the start. New trays were provided in 2007, but the capacity only increased marginally. In 2008, another detailed capacity study was enacted including gamma scans of the tower. The top few trays showed unusual absorption on the Gamma Scans. The buildup of water in the tower was suspected. The spare pump line was drained and found to be totally full of water. After further draining, an abundance of foam came out of the spare pump line. The lessons learned from this experience and the solutions to the tower were discussed. This is an abstract of a paper presented at the 2013 AIChE Spring Meeting & 9th Global Congress on Process Safety (San Antonio, TX 4/28-5/2/2013). Source

Summers D.R.,Sulzer Chemtech United States Inc.
Chemical Engineering Progress | Year: 2010

The procedure followed by engineers to conduct a good performance evaluation of a distillation tower and document the results efficiently is discussed. Vapor-liquid equilibrium (VLE) model is employed such as Peng-Robinson or Soave-Redlich-Kwong equation-of-state model for a hydrocarbon separation to obtain the information to evaluate the performance of the tower. Readings from a flow element are transmitted to the flow-control computer as a milliamp (mA) signal, where 4 mA represents zero pressure drops, 20 mA represents the highest pressure drop that the flow element is calibrated to measure. The reboiler duty is evaluated by the flowrate of the heating fluid to the reboiler/condenser and on the basis of reboiler duty, the tower can be simulated and the resulting reflux flowrate is compared to the observed reflux flowrate. The observed pressure drop across a column is obtained with differential pressure cell that measures the pressure difference between two elevations of the tower and by calculating the difference of local pressure measurements from two tower pressure taps. Source

Summers D.R.,Sulzer Chemtech United States Inc. | Spiegel L.,Sulzer AG | Kolesnikov E.,Sulzer AG
10AIChE - 2010 AIChE Annual Meeting, Conference Proceedings | Year: 2010

Tower operation at low vapor rates is typically limited by the onset of weeping which can severely hurt tray performance. Many authors have attempted to study the onset of weeping on distillation trays as well as to determine the amount of weeping present. This paper will address this issue from a different perspective which is the uniformity of vapor passage through the tray deck at low vapor loads. It will be shown that there exists a relationship between the onset of weeping, tray performance, dry tray pressure drop and hydrostatic head of liquid on the tray. In addition, this relationship will be addressed with regards to single pass as well as multi-pass trays. Source

Schlummer C.,Sulzer AG | Ulicney N.,Sulzer Chemtech United States Inc.
Society of Plastics Engineers - FOAMS 2010, 8th International Conference on Foam Materials and Technology | Year: 2010

Although foam extrusion is a well established process, a noticeable growing interest in the market could be observed in recent years. Foamed products offer both, economical and technical advantages such as weight reduction, material savings and enhanced properties like damping and insulation behaviour. Chemical and physical blowing agents are widely used in foam extrusion processes, both finding their way in specific application. When physical blowing agents are used, conventional technical solutions characteristically require special foam extrusion lines comprising specific plasticising screws and barrels for foaming. An alternative technology and retrofit solution has now been developed. The system utilizes a special fluid injection nozzle with an arrangement of static mixers downstream of the extruder barrel for absorption of blowing fluids and homogenization of the two phase mixture into a single phase solution. The main advantage of this approach is the flexibility and easy implementation. Conventional extruders can be retrofitted to foam extrusion lines without any modification to the plasticising screw and barrel. However, certain process and design criteria need to be fulfilled to achieve satisfying foaming results. The paper introduces the retrofit concept for foam extrusion with physical blowing agents, explains the correlation with the foaming process, states advantages and limitations and shows recent developments in low density foam application and foaming of rigid PVC. Source

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