A Continuous Steady state Distillation Column is Fed a Mixture

Continuous Distillation Column (UOP3CC)

• Description of apparatus:

The UOP3CCContinuous Distillation Column is a self-contained distillation facility consisting of two interconnected units: a floor standing process unit and a bench- mounted control console. The distillation column is mounted on a floor standing, welded tubular steel framework (1) fitted with four adjustable feet (2). The frame is designed to allow the use of a fork lift or pallet truck to manoeuvre the unit into position initially.

The 50mm diameter sieve plate column is made up of two glass sections (3) and (4) each containing four sieve plates. The columns are separated by a central feed section and arranged vertically for counter-current vapour/liquid flow. The column is insulated to minimise heat loss.

Feed mixture from either of the feed tanks is pumped by pump (7) to the base, centre or top of the distillation column at connections (A), (B) or (C) respectively. The feed pump incorporates a length of Viton rubber tubing. This tubing is suitable for all of the recommended test mixtures (see "Operational Procedures"). Where other test mixtures are being used, the suitability of this material must be checked.

A packed column is supplied loose. This column can be fitted in place of the sieve plate column where it is required to demonstrate the characteristics of a packed column.

The reboiler (13) situated at the base of the column is manufactured from 316stainless steel and incorporates a flameproof immersion type heating element. Either batch or continuous distillation can be carried out using this reboiler.

Vapour from the top of the column passes to a water-cooled, coil-in-shell condenser (8), which may be fitted with an insulated jacket to allow heat balances to be carried out. (The insulated jacket should not be fitted to the condenser for normal operation.) The shell of the condenser incorporates a pressure relief valve (PRV1) to protect the system in the event of a blocked vent and cooling water failure. Cooling water enters the condenser at a regulated rate through a variable area flowmeter (FI1) and the flowrate is controlled by diaphragm valve (V5). A cooling water supply is connected to the inlet nozzle (19) and serves also to operate the vacuum pump (20) when operation at reduced pressure is required. Water supply to the vacuum pump is controlled by valve (V14), which must only be operated when valve (V5) is open.

Temperatures within the system are monitored by fourteen thermocouple sensors (T1 to T14) located at strategic positions in the system. T1 to T8 are located in the column and measure the temperature of the liquid on each sieve plate. There are seventeen locations for the temperature sensors, three of which do not have sensors installed but which can be fitted with sensors moved from other, less relevant locations when necessary.

The total pressure drop across the column is indicated on a U-tube manometer (∆P1) via appropriate tappings in the column fitted with isolating valves (V6) and (V7).

The console is attached to the process unit by an umbilical cable which is of adequate length to allow the console to be positioned at least 2.0m away (outside the "Zone 2" area). See the Safety section at the front of this manual, and the Specifications section on page 22.

• Experiments done on it:

1. Unit Lab

   • Batch Distillation

     • Variation of Column Pressure Drop:To determine the pressure drop over the distillation column for various boil-up rates

     • Determining Mixture Compositions Use the refractometer:It is essential to have a convenient quick method of determining the composition of the binary mixture taken from the various sample points on the distillation column. Such a method involves the use of a refractometer since the refractive index of these mixtures varies with composition.For the system Methanol/Water, mixtures of known concentration can be made up and their refractive indexes measured. The refractometer measured the critical angle of the liquid under test and each concentration will show a different critical angle.

     • Overall Column Efficiency:To determine the overall column efficiency at varying boil-up rates.

     • Distillation at Constant Reflux Ratio:To carry out a distillation at constant reflux ratio-varying top and bottom compositions with time.

   • Continuous Operation

     • Steady State Distillation of a Binary Mixture:To operate a steady state distillation of a binary mixture under continuous operation. The equipment will be set up to operate at total reflux so that the charge of feed mixture can be loaded directly into the reboiler

     • Varying the Feed Position :To find the effect of varying the feed position under continuous operation .

2. Control Lab

Using a PID Controller: In distillation control there are several requirements that must satisfy such as: Safety, Production specification, Environmental regulations, Operational constrains, Economics.

The input variables can be further classified into the following categories:  1- Manipulated (or adjustable) variables. 2- Disturbance.

At First the manipulated variables and disturbances and set point must be considered.

The UOP3CC distillation column can be used for single loop process control demonstrations using a PID process controller. It possible to configure 2 different control loops:

• Reboiler power control from a column temperature (T7).

  • Open Loop System

  • Close Loop System

  • Optimize the P, I, D settings

  • Effect of external disturbance

• Reflux control from the top tray temperature (T1).

  • Optimize the controller settings

  • Effect of external disturbance

The object of the experiment can be:

• Demonstrate a typical application of a PID process controller.

• Observe the response of the process to a change in set point or disturbances.

• Adjust the settings of the controller from optimum control of the process

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Source: https://eng-old.najah.edu/apparatus/2376

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