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AIChE Equipment Testing Procedure - Trayed and Packed Columns A Guide to Performance Evaluation

  • Erscheinungsdatum: 03.02.2014
  • Verlag: Wiley-AIChE
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AIChE Equipment Testing Procedure - Trayed and Packed Columns

This new edition of a trusted guide combines and updates the best available field knowledge on both trayed and packed distillation columns. In one complete, user-friendly volume, it presents a compilation of techniques rather than a single set of compulsory steps, allowing readers to select the procedure that best suits their needs. With its engineer-tested procedures and detailed explanations, the third edition provides chemical engineers, plant managers, and other professionals with first-class advice on assessing and measuring performance for a variety of distillation column types in multiple applications.


    Format: PDF
    Kopierschutz: AdobeDRM
    Seitenzahl: 152
    Erscheinungsdatum: 03.02.2014
    Sprache: Englisch
    ISBN: 9781118860540
    Verlag: Wiley-AIChE
    Größe: 4522 kBytes
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AIChE Equipment Testing Procedure - Trayed and Packed Columns


201.0 Flow Quantities

(Refer to Figure 1 )

Figure 1. Graphic Description of Terms

201.1 Feed is the material to be separated, including multiple feed streams.

201.2 Bottoms describes the high-boiling product leaving the bottom of the column (or the reboiler).

201.3 Distillate is the product distilled overhead. It may leave the distillation system as a vapor, liquid, or a combination of both.

201.4 Side-stream Product is product withdrawn from an intermediate section of the column.

201.5 Overhead Vapor designates the vapor from the top of the column and includes material to be condensed for reflux. It is the combined distillate and external reflux.

201.6 Reflux is used to designate the quantity of liquid returned to the column.

201.6.1 External (Overhead) Reflux is the quantity of liquid returned to the top of the column. External reflux may be subcooled, which can result in increased internal reflux.

201.6.2 Internal Reflux is the calculated quantity of liquid leaving the top theoretical stage inside the tower. The internal reflux is different from the external reflux in that it is in thermal equilibrium with the top theoretical stage inside the tower.

201.6.3 Pumparound is the quantity of liquid withdrawn from, and returned to, the column after being cooled. A pumparound can be subcooled, and then returned to the tower at a location other than the top. A pumparound is sometimes called Circulating Reflux.

201.6.4 Reflux Ratio is the ratio of the external reflux flow to the distillate. Some applications may use the ratio of external reflux flow to feed to represent the reflux ratio.

201.7 Throughput refers to the combined liquid and vapor traffic passing through a cross section of the column.

201.7.1 Internal Liquid is the calculated quantity of liquid flowing from point to point in the column.

201.7.2 Internal Vapor is the calculated quantity of vapor passing from point to point in the column.

201.7.3 Entrainment is the liquid carried upward by the vapor stream from one point to another.

201.7.4 Weeping is the liquid that flows downward through the deck openings in trayed towers.
202.0 Key Components

A key component is a component of interest in a column. In a multi-component mixture, separation is based upon the lower boiling "light key" and the higher boiling "heavy key." At times components with boiling temperatures between those of the light and heavy key may also be present. Such a component may be called a "middle boiler," an "intermediate," or a "distributed key."
203.0 Mass Transfer Efficiency

The efficiencies used in describing the performance of fractionation columns are briefly described below [1].

203.1 Theoretical Trays or Plates or Stages are stages on which the vapor and liquid streams leaving the stage have reached thermodynamic equilibrium.

203.2 Overall Column Efficiency refers to the performance of the column as a whole. For trayed columns, this efficiency is the ratio of the number of theoretical trays or stages that would be required for the observed separation to the number of actual trays in the column. This number is dimensionless and is usually expressed as a percentage.

For packed columns, the HETP (Height Equivalent to a Theoretical Plate) for the column as a whole is the ratio of the overall height of packing in the column to the number of theoretical stages in the column. Thi

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