THE 3
rd
INTERNATIONAL SCIENTIFIC CONFERENCES OF STUDENTS AND YOUNG RESEARCHERS
dedicated to the 99
th
anniversary of the National Leader of Azerbaijan Heydar Aliyev
270
preventing an overfill.
If the level of a liquid, a solid or a liquefied gas is not
monitored and controlled properly, it can severely damage equipment and
result in undesirable change in the product quality or loss of production.
In various industrial applications, control loops are the systems to maintain
a process variable at a desired value - set point. They are important to maintain
stability in the system and to consistently produce the desired outcome of the
process.
This system consists of the sensing device, the controller, and the
final control element (FCE), which are all required for automatic control. The
purpose of the project is to set up and configure a level control loop at the
BHOS Emerson test rig. The loop devices used are “Radar Level Transmitter
5300” as a measurement device, “EZ control valve - 667 actuator- DVC6000”
as a final control element, “DeltaV Hardware & Software” as a controller and
“Variable Frequency Drive” as a disturbance source.
In order to have a proper, safe
and accurate level measurement,
measurement devices must be selected for the paramaters of the given
system based on analysis of the technologies and vendors. Level sensors
can use a contact or non-contact measurement principles.
The temperature
or pressure of the process material could affect the reading of the contact
sensor, damage it or cause any other troublesome problems. As a non-
contact type of level sensors is more adaptable to the system, radar level
transmitter is chosen for the loop.
The controller is the component of the control
loop that interprets the
sensor readings and decides on the control action based on a comparison of
that value to the set point. The PID Algorithm is a common form of the
feedback control at which the combination of integral and derivative controls
provides the decreased or zero offset and the addition of proportianal control
provides a quicker response time. Most feedback control loops are controlled
by this algorithm or its minor variations of it. As a derivative mode is complex
for this basic loop, the PI control technique is
selected as the controller
algorithm for the given system.
Lastly, proper final control element must be selected for the system. The
final control elements are the devices, which get the control action signals
from the controller and adjust the process variable to the desired value.
There are several common types of FCEs of the control loop, such as a
control valve, Variable Frequency Driver, or a solenoid valve. Although VFDs
has the economic benefits, they will not operate properly at very low speeds.
Therefore, a control valve is chosen for the given
loop to achieve a wide
range of speeds in the system. The selected control valve will adjust a flow
of fluid to compensate for the load disturbance and maintain the process
variable near to the desired set point.
In the implementation stage, the program has been developed in DeltaV
software provided by Emerson with the required logic and communication has