Multi-Function Process Control Teaching Style Electronic
Description
Basic Process Control System
It contains everything that is needed to perform a range of single-loop
process control experiments in conjunction with a PC.
It includes a variable volume process tank, a hot water tank with
electric heater and indirect heating/cooling coil, a hot water pump, two
non-dedicated pumps, three on/off solenoid valves and a proportioning
valve. The instrumentation includes temperature sensors, two
differential water pressure sensors, a mechanical level sensor (float
switch) and an electronic level sensor (conductivity). The inlets and
outlets of the various pumps, valves and tanks incorporate self-sealing
quick-release fittings. This enables the configuration to be quickly
changed, offering a wide variety of different loops.
It includes a computer interface (USB), and all of the parameters can be
controlled directly from the computer, (i.e. the pump speeds), the
valve positions and the heater power. The computer also displays the
readings from the various measurement sensors. The software supplied
with the unit includes on/off, time proportioned and
proportional/integral/derivative (PID) algorithms where all the
parameters are easily accessed and adjusted by the user. This approach
means that a separate electronic console is unnecessary for most
applications.
The flexible nature of the system also enables a wide variety of
different disturbances to be applied to the loops to permit the
effectiveness of the control parameters to be compared. As all these
disturbances are under software control, they can be repeated precisely
during the optimization process, thus enabling an excellent degree of
fine-tuning to be implemented. A pressure regulating valve with filter
is also included to isolate the equipment from fluctuations in the water
supply pressure.
The Type Of Loops Achievable With The Basic Include:
Tank water level by varying input flow
Water flow rate by varying pump speed
Temperature of water in a vessel by varying the heater power
Temperature of water heated indirectly by varying the flow rate
(All these loops are under software control)
Process Vessel Accessory
It extends the capability of the basic by adding an additional process
vessel, complete with a heating/cooling coil and a stirrer. The inputs
and outputs incorporate quick release fittings, enabling the added
quickly and easily.
This is also includes a conductivity probe to enable cost-effective
fluid property demonstrations to be performed.
The addition of the process vessel enables more complex process control
problems to be addressed, including remote setpoint demonstrations.
Again these all take place with the repeatability advantages that
electronic and software control brings.
Additional loops that can be implemented with it include:
Single Loops in Combination:
- Conductivity control of reactor contents by varying flow rate of one component
- Temperature control of reactor contents by varying heating fluid flow rate
- Temperature control of heating fluid by varying heater power
Remote Setpoint Control:
- Ratio control of two flows
- Cascade control of conductivity and flow
- Feedforward control of flow to flow
- Feedforward control of flow combined with feedback control of conductivity (All these loops are under software control)
pH Sensor Accessory
This is a conductivity probe as part of the basic supply. This
conductivity probe can be used to demonstrate fluid property control
systems without the maintenance problems, which can be experienced with
pH probes. However, as pH control is probably the most common industrial
application of this type of control system, users may wish to implement
true pH control loops.
Electronic Console
This is an electronic console that can be used to control the instead of
a computer. It includes controls for the pumps, valves and heater, plus
a display for the sensors. It incorporates a commercial PID controller,
complete with RS232 interface. Other facilities include four 20mA
interfaces and selector switches to enable many of the different
configurations to be implemented without using external jumper
connections.
This is single-loop configurations to be implemented without using a
computer. Using this console also enables the sensor data to be logged
and displayed on a computer (using the interface), but with the control
functions being implemented in the hardware, rather than the computer
software.
Facilities include:
- Use of a commercial PID controller
- Simple interfacing to other PLC and/or PID controllers
- Use of four 20mA interfaces
- Use of serial communications (RS232) in a control system
- Simple SCADA demonstration (requires PC)
Pneumatic Valve Module Accessory
This is a pneumatic control valve, plus associated components, for use
with the system. Retaining the flexible concept of the whole range, it
can be plumbed into many of the flow control loops, and provides a good
illustration of pneumatic valve technology.
Technical Specification
- A multi-function process control teaching system, capable of demonstrating level, flow, pressure and temperature control loops
- Bench mounted and includes a built-in USB computer interface
- Options include: reactor vessel with conductivity measurement, pH measurement, pneumatic control valve and electronic console
- Includes the following process control demonstrations:
Process principles
- Calibration of sensors (via PC software)
- Inflow control
- Outflow control
- Direct heating
- Indirect heating
- Batch operation
- Continuous operation
- Effect of sensor lag (eg thermometer pocket)
- Effect of system time constant (eg volume change)
- Effect of dead time (eg holding tube)
- Effect of mixing/stirring
Measured Variables
- Level – on/off switch (fixed hysteresis)
- Level – differential on/off switch (adjustable hysteresis)
- Level – proportional pressure sensor (slow system response)
- Flow – proportional turbine sensor
- Temperature – on/off switch (fixed hysteresis)
- Temperature – proportional thermocouple sensors
- Static pressure – proportional sensor (fast system response)
- Differential pressure – proportional pressure (fast system response)
- pH – proportional sensor
Controlled Variables
- On/off flow control via solenoid valves
- Time-proportioned flow control via solenoid valves
- Proportional flow control via pump speed
- Proportional flow control via electrical proportioning valve
- Proportional flow control via pneumatic proportioning valve
- On/off heater power control via solid state relay
- Time proportioned heater power control via solid state relay
- Proportional heater power control via solid state relay
Controller Types
- Manual control
- Effect of reverse/direct action
- On/off output with hysteresis
- Time proportioned output with adjustable P, I & D terms and cycle time
- PID proportional output with adjustable P, I & D terms
- Remote setpoint control
- Ratio, cascade and feedforward with feedback loops
Multi-Function Process Control Teaching Style Electronic ALTEC Laboratory Equipments and ALTEC Laboratory Instruments Tenders.