Blending Experiment
Aims
The aims of this experiment are:
- To analyse a system with multiple control loops using the RGA method
and hence decide on the optimal method of matching up the measured
variables with manipulated variables
- To see the effect of differing experimental conditions in the above
analysis
- To run the system with two control loops in place to see the
interaction of the two control loops
Theory
The theory describing how to obtain and analyse the RGA can be found in:
Module 6 - Multivariable Systems.
Experimental Apparatus and Procedure
The experimental setup for this simulation consists of:
- A tank with two inputs and one output:
- Input 1 is a concentrate stream
- Input 2 is a diluent stream
- Output depends on level in tank
- Three controllers:
- Controller 1 (with lag) controlling the level
- Controller 2 (with delay) controlling the concentration
- Controller 3 is a flow controller on one stream ie one flowrate is
constant
There are two different ways of running the above system.
- With a constant outflow
- With a constant diluent flow
The experimental setup and procedure for each is discussed in turn below.
Constant Outflow
The first set of experiments deals with a constant outflow
- Controller 3 is placed on the outflow from the tank so that there is
a constant valve constant and the outflow depends only on the level in
the tank.
- Manipulated variable 1 is the concentrate flow
- Manipulated variable 2 is the diluent flow
- Measurement 1 is the concentrate concentration
- Measurement 2 is the level
The experimental apparatus therefore is shown below:
The aim of the experiment is to try and match up the measurements and
manipulations using the RGA method discussed in the theory section.
This will depend in part on the initial conditions in the tank and the
operating conditions during the experiment. Therefore there are two
different experiments.
Following the links below will take you to a further discussion about
the experimental conditions along with pre-experimental questions to
guide you through each simulation.
Constant Diluent Flow
The first set of experiments deals with a constant diluent flow.
- Controller 3 is placed on the diluent flow which stays constant
throughout.
- Manipulated variable 1 is the concentrate flow
- Manipulated variable 2 is the flow out valve constant
- Measurement 1 is the concentrate concentration
- Measurement 2 is the level
The experimental apparatus again is shown. Note that this time there is
only one way to run this experiment.
The first aim of this experiment is to evaluate the gain matrix and RGA
and show that there is only one way to match up these variables (the
flow out from the tank does not have any effect on the concentration in
the tank). The second aim of the experiment is to run the two loops
separately and then run them together to see how they interact and how
the tuning is affected.
Following the link below will take you to a further discussion about
the experimental conditions along with pre-experimental questions to
guide you through the simulation.
Return to the Virtual Control Laboratory