Major Project Review 2

CONTROL OF REACTIVE DISTILLATION COLUMN USING FUZZY LOGIC

C H - 4 0 9 2 P RO J E C T R E V I E W 1

G U I D E : D R . M A L L A D I PAVA N K U M A R

Saurab DevanandanManu VishalSajin Jose

Outline of presentationObjective

Procedure completed

System definition

Sensitivity analysis

Controller tuning

Proportional integral control implementation

2

OBJECTIVETo obtain the most sensitive trays in the stripping and reactive sections

Perform controller tuning using Relay Feedback Mechanism

Implement 2- Point control using PI control mechanism

Procedure CompletedSensitivity analysis was performed under steady state

Controller Tuning was performed Gain and Integral time was determined for control of both feed rates

Proportional Integral Control was implemented

Reactive Distillation SystemIdeal system: A+B C+D

Relative volatilities: C>A>B>D

Distillation column having 22 stages including reboiler and condenser

Feed introduced in tray 9 and tray 14

Constant reflux operation

Control structure 1

Control structure 1The control scheme CS1 in which the purities of both products are measured and controlled.

The reflux-drum level is controlled by the distillate flow rate. Corresponding change is reflected in the reflux flow rate.

In many practical applications it may be necessary to use temperature measurements instead of composition measurements.--- inferential control

In the bottoms, the flow rate of component D is manipulated to implement the level control of bottoms holdup.

All control valves are designed to be half open at the initial steady state. Therefore, all manipulated variables cannot increase more than twice their steady state values.

Feed flow rates are manipulated. Reboiler heat duty is kept as the throughput manipulator.

Sensitivity analysisMost sensitive trays in reactive and stripping sections were determined to be tray no. 3 and 10.

These trays were used in the 2 point control implemented.

Tray temperature change was observed for 1% change in feed rates (Fa ,Fb) and Reboiler duty(Qr)

Sensitivity analysis

Controller tuningController tuning done using Relay Feedback mechanism

Calculated Values:-Ultimate Gain for Fa control = 4.870723722855942e+000Ultimate Gain for Fb control = 1.183496555512724e+000Integral Time for Fa control= 16.28Integral Time for Fb control= 18.92

RELAY FEEDBACK TEST For a majority process plants, the so-called auto tuning" procedure for the tuning of PID controllers can be used. Such a procedure is based on the idea of using an on/off controller (called a relay controller)

Starting from its nominal bias value the control action is increased by an amount denoted by h and later on decreased until a definite and repeated output response can be easily identified.

the ultimate gain can be computed as:

Feed rate of B

Temperature response

Feed rate of A

Temperature response

Proportional Integral ControlPI control was implemented for unit step change in Reboiler heat duty

Response to positive and negative step changes were observed

Plots were obtained for responses of product purities, Feed rates , Tray Temperatures

Step change magnitude: 10%

Positive step change input-Reboiler heat duty

Temperature response

Product purities response

Feed B rate response

Feed A rate response

Negative step change input-Reboiler heat duty

Temperature response

Product purities response

Feed B rate response

Feed A rate response

Plan of approachSl no

Plan Period

1 Fuzzy logic control January

2 Familiarising with matlab fuzzy logic toolbox February3 Finalising data sets February4 Developing MATLAB code for optimized control of an

ideal system A+B C+D using fuzzy logicMarch

5 Plot the results April

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