UOP7 MKII – Gas Absorption Column


UOP7 MKII – Gas Absorption Column

The Armfield Gas Absorption Column has been designed to demonstrate the principles of gas absorption and to provide practical training in the operation of a gas absorption plant.


The Armfield Gas Absorption Column has been designed to demonstrate the principles of gas absorption and to provide practical training in the operation of a gas absorption plant.

In the process of gas absorption, a mixture of gases is contacted with a liquid, for the purpose of dissolving one or more components of the gas and to provide a solution of them into the liquid.

In the UOP7MkII, a gas phase consisting of CO2 and air is introduced into the bottom of the packed column. Adjustment of their flow ratio is obtained by manual valves. A sample of the gas mixture is sent to a CO2 concentration sensor located inside the electric console, and readings of flows and percentage CO2 concentration is visible on the display screen as well as in the software.

For the liquid phase, water (or a solution of sodium hydroxide) is pumped to the top of the column where it falls through the packing material. The gas and liquid phase flows counter-currently. This increases the contact time and diffusion of CO2 into the liquid phase.

The outlet gas leaves the system from the top of the column. A sample of the outlet gas mixture is also taken and sent to the CO2 sensor inside the console. Reading percentage of CO2 is shown on the console display screen.

The liquid leaves the system from the bottom of the column and returns to the feed tank or to drain. Samples of the liquid phase entering and exiting the system can be taken for further analysis via the sampling ports.

Desorption of the CO2 absorbed in the water line is obtained by aeration of the “enriched” liquid.

Unit Characteristics

The packed absorption column is made of clear acrylic and is installed vertically on a mild steel floor-standing framework. The column is filled with 10mm x 10mm of glass Raschig rings, which are representative of random packing used in gas absorption in industrial applications. Liquid is stored in a feed tank and a variable-speed submersible pump is used to pump the liquid into the column. An electronic flow meter sensor is installed in the liquid stream to provide accurate measurement of the liquid flow entering the column.

The gas to be absorbed is carbon dioxide (CO2), and would be taken from a pressure cylinder (not supplied). Gas regulator, control valve and electronic flow meter are used to regulate gas flow. A centrifugal fan provides air flow to the column. The air line includes a gate and electronic flow meter for accurate flow control and measurement.

Pressure tappings at the base, centre and top of the column are provided to enable indication of pressure drops in the column using electronic pressure sensors.

Liquid and gas temperature readings are obtained by thermistors in the liquid tank and the inlet gas line.

Technical Specifications

Features & Benefits

  • Simple gas absorption and gas desorption demonstration
  • Electronic instrumentation for flow (air, CO2, liquid), temperature (liquid and gas) and the pressure drops through the column
  • Electronic measurement of CO2 concentration on the gas inlet and outlet
  • Electronic control of liquid flow
  • Data logging facility


  • Study of basic principles of the absorption of a gas into a liquid using a packed column
  • Determination of loading and flooding points
  • Study of hydrodynamic characteristics of a packed column
  • Demonstration of physical and chemical absorption
  • Investigation of the effectiveness of CO₂ absorption in pure water and in an aqueous solution
  • Demonstration of gas desorption
  • Determination of the mass transfer coefficient

  • An apparatus for teaching the principles of the absorption of gas into liquid, using a packed column
  • Column working length is 1.4m x 80mm diameter, split into two sections
  • Two electronic pressure sensors measure the pressure drop across each half of the column
  • An electronically controlled submersible pump provides a liquid flow of 1-10 l/min
  • 60l feed tank
  • Water flow can be used in either recycle or one-pass operation
  • Column supplied with 10mm x 10mm Raschig rings as packing material, total volume 7l. Other sizes can be used
  • Centrifugal fan provides air flow up to 160 l/min
  • Two electronic temperature sensors measure the air and liquid temperatures
  • Electronic measurement of CO2 concentration in the air streams, measurements can be taken at the column inlet and outlet
  • Sensor values displayed on an alphanumeric display on the control console
  • Data logging as standard (requires PC, not supplied)

Electrical supply:

UOP7-MkII-A: 220-240V/1ph/50Hz, 2A
UOP7-MkII-B: 115V/1ph/60Hz, 4A
UOP7-MkII-G: 220-240V/1ph/60Hz, 2A

Water supply: 5 l/min at 2 bar

CO2: 20 l/min at 1 bar

Computer: A Windows PC (not supplied) running Windows 7 or later, with USB port is required if running the data logging software


Volume: 2.2m³

Gross Weight: 200Kg

Length: 1.017m

Width: 0.667m

Height: 2.876m (1.781 disassembled)

  • UOP7-MkII-A: 220-240V / 1ph / 50Hz / 2A
  • UOP7-MkII-B: 115V / 1ph / 60Hz / 4A
  • UOP7-MkII-G: 220-240V / 1ph / 60Hz / 2A
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