Chemical and Biological Engineering ETDs

Jaw-Ruey Leu

Publication Date

1978

Abstract

In a conventional gas-liquid contacting system that provides a long gas-liquid contact time, a pressurized gas is released at the bottom of a pool of liquid to form gas bubbles; the bubbles move upward through the liquid and break at the surface of the liquid. A large amount of work is spent in pressurizing the gas. Even though it is theoretically possible to recover work from rising bubbles, a work recovery scheme has not been incorporated into a conventional system.

A buoyancy-balanced gas-liquid contacting system concept has recently been introduced. The system comprises two processing zones filled with a liquid, multitude of compartments holding a gas phase, a transmission means that is subjected to a peripheral motion and moves through the two processing zones, each compartment being attached to the transmission means and moving downwardly in the first zone and upwardly in the second zone. Thus, the buoyancy forces acting on the compartments in the upward motion balance with the buoyancy forces acting on the compartments in the downward motion. An effective gas-liquid contact is established between the gas phase held in each compartment and the liquid phase in which the compartment is submerged. Gas is fed into each com­partment at the top of the first zone and unabsorbed gas in each compartment is released from each compartment when it reaches the top of the second zone. It is likely that a saving in work input can be realized in such a gas-liquid contacting system. The primary objective of the present thesis study is to gather information needed for making a preliminary feasibility study of the process. The work accomplished includes the following subjects:

  1. Component parts requires have been identified and methods of fabricating them have been proposed.
  2. A model system has been constructed and operated to demonstrate how the system works.
  3. A theoretical analysis for studying rate of absorption of a component in a gas contained in a compartment submerged in and descending through a liquid phase has been made.
  4. The analysis has been applied to gas-liquid systems having Henry’s Law constants in the range of 3.3 x 10 5 mm Hg to 3.3 x 10 7 mm Hg and diffusivities in the range of 7.4 x 10 -6 cm2/ sec to 2.57 x 10 -4 cm2/sec.

Conclusions that have been drawn from the study are:

  1. An industrial buoyancy-balanced gas-liquid contacting system can be constructed and successfully operated.
  2. When the system is applied to treat a gas-liquid pair, the gas solubility is the key factor determining the economic feasibility of the process.
  3. The system may be used economically in treating a medium solubility gas-liquid pair having Henry’s Law constant less than say, 1 x 10 5 mm Hg.
  4. It may not be economically feasible to use the system in treating a vey low solubility gas-liquid pair having Henry’s Law constant greater than 1 x 10 7 mm Hg.
  5. It is essential to incorporate an efficient way of agitating the liquid interface, in each contacting compartment. This is particularly important when the system is used in treating a low solubility gas-liquid pair.

Document Type

Thesis

Language

English

Degree Name

Chemical Engineering

Level of Degree

Masters

Department Name

Chemical and Biological Engineering

First Committee Member (Chair)

Chen-Yen Cheng

Second Committee Member

H. E. Nuttall

Third Committee Member

Richard W. Mead

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