SUGISAKAMASANORI

Journal of Advances in Artificial Life Robotics
Vol. 4(4); March (2024), pp. 193–199
ON LINE ISSN 2435-8061; ISSN-L 2435-8061
https://alife-robotics.org/jallr.html

International JournalAdvances in Artificial Life Robotics
ICAROB series
Editor-in-Chief
Masanori Sugisaka
Co-Editor-in-Chief
Takao Ito

ISSN 2435-8061
Publisher Masanori Sugisaka(Global Register of Publishes)
regstrated in Jan, 25, 1996
Handadai Higashi 2-8-4, Oita, 870-1108, Japan

Research Article

Research on the Simulation of Chemical Reactors Utilizing thePCS7 Platform
Hongshuo Zhai

Tianjin University of Science and Technology, Tianjin, China

ARTICLE INFO
Article History
Received 11 November 2023
Accepted 11 July 2024
Keywords
PCS7
PID adjustment
Industrial control
Chemical reactor

ABSTRACTThe rapid development of industrial control and its systems since the 1960s has been mainly due
to the remarkable progress of key process control theories, which are increasingly used in the fieldof science and technology. Often, there are multiple potential risks in a factory environment, sopeople tend to use remote and precise control methods. This study using PCS7 remote control
software to simulate the chemical reactor process, and through the PID adjustment to ensure therationality of the results of simulation and accuracy.

© 2022 The Author. Published by Sugisaka Masanori at ALife Robotics Corporation Ltd.
This is an open access article distributed under the CC BY-NC 4.0 license(http://creativecommons.org/licenses/by-nc/4.0/).

uses CFC and SFC modules to build a simulation modeland realize the automatic control of the reactor. By
adjusting the PID control strategy, we optimize theperformance of the simulation system and ensure theaccuracy and reliability of the simulation results. Finally,
we show the change of key parameters in the simulation
process, which provides an intuitive reference for remotecontrol of chemical reactors.

1. Introduction
The normal functioning of human society depends on the
support of chemical reactions, which are carried out inspecial containers called chemical reactors. These devices
play a vital role in many fields such as chemical,
pharmaceutical and energy, and are designed to ensure
efficient production while producing quality products.
Although the operating environment of chemical
reactors may contain a variety of hazardous substances thatpose risks to human health and the ecological environment,with the advancement of technology, we have been able toreduce direct contact through remote control technology,
thus ensuring operational safety. This control method not
only improves the safety of operation, but also makes thecontrol of the reaction process more accurate.
In this study, PLC-SIM is used as the simulation
controller, and the remote control process of chemical
reactor is simulated by PCS7 software. This paper first
introduces the architecture and operation interface ofPCS7 software in chemical reactor simulation, and then2. PCS7 Project Basic Framework
In most industrial automation projects, common systemcomponents include ES (engineer station), OS (operatorstation), AS (automatic station), and the communication
bus between them. Each of these sites has a unique set oftasks and functions, as shown in Fig. 1.
In simple terms [1], the ES station usually acts AS thecentral node for project configuration and monitoring, theOS station provides real-time data display and userinteraction interface, and the AS station is directly
connected to the production process and executes specificcontrol logic. In addition, the communication bus acts as alink for information transmission, ensuring data

Corresponding author’s E-mail: 1936130557@qq.com URL: www.tust.edu.cn193

the safe storage and easy retrieval of historical data.
Protocol design is also an important part, which defines therules and formats of data exchange to ensure compatibility
and effective communication between different systems
and devices. Through these integrated designs andconfigurations, the operation station becomes an important
hub for monitoring and controlling industrial processes.

synchronization and instruction transmission between
stations. This structural design not only improves thereliability and flexibility of the system, but also facilitates
remote monitoring and fault diagnosis, thus optimizing theoperation efficiency and maintenance management of theentire project.

2.2. Automation station
The Automation station (AS station) forms the core of theSiemens distributed control system and consists of several
key components, including the rack, the power module(PS), the central processing unit (CPU) and theinput/output (I/O) module.
In PCS7 systems, the CPU 400 series is widely used,
and they are installed in racks (racks). In addition to CPUmodules, the rack also contains communication processor(CP) modules, which are specifically responsible forcommunication tasks with other systems. In addition,some CPU modules are also integrated with
communication functions, such as having PROFIBUS DP
interfaces or as serial communication modules, thus
enabling direct communication with other devices.
The automation station uses fast industrial Ethernet
technology to connect to the entire system, ensuring highspeed data transmission and processing. At the same time,the engineer station is connected to the ET200 distributed
I/O station through the Profibus-DP fieldbus, which not
only improves the flexibility of the system, but alsoenhances the real-time data acquisition and control. In thisway, the engineer station can efficiently monitor andcontrol I/O devices distributed in different geographicallocations, enabling precise management of the entire
automation process. Note: The "block" in PCS7 is very
critical, it is related to the work of the CPU in the software
STEP7, the specific utility is shown in Table 1.

Fig. 1 PCS7 framework
2.1. Engineer station
The engineer station (ES station) has the core function ofcreating and modifying project files, but also coordinates
the data exchange and communication between theautomation station (AS station) and the operator station(OS station). Under normal circumstances, theconfiguration of ES station is realized through SIMATICManager software, which is mainly divided into two key
steps: The first is the configuration of automation station,
which involves the control logic and hardware Settings;
The second is the configuration of the operator station,
which is related to the user interface and data presentation.
For the configuration of automation stations, it covers
multiple levels of work, including but not limited to thedrawing of continuous function diagrams (CFC) andsequential function diagrams (SFC), which are key tools
for describing the flow and sequence of operations ofindustrial processes. In addition, factory-level design isincluded to ensure that the automation system matches thelayout and needs of the entire plant; Hardware
configuration, ensure that all hardware devices arecorrectly set up and work together; And communication
network configuration, establish a stable and reliable datatransmission path.
In the design of operator stations, the focus is on
creating intuitive and easy-to-use process monitoring andoperation interfaces that not only present real-time data,
but also provide operators with the necessary means ofcontrol. At the same time, the operation station is also
responsible for the archiving management of data to ensure

Table 1 Utility of blocks
BlockTissue block (OB)

System Function Block(SFB)
andSystem
Function Call Block(SFC)
194

UtilityThefunctionisresponsiblefor
sequentially storing theuser's master program andcontrol logic.
These programs andcontrol logic are stored in
the S7 CPU to ensure thatsome built-in retention

Functional Block (FB)

Function(FC)callblockBackground Data block(INSTANCE DB)

Data block (DB)System(SDB)

DataBlockprocess, but also provides the operator with an efficientand intuitive work platform, thereby improving theoperational efficiency and reliability of the entire
industrial automation system.

functionscanbeperformed.
It is used to store
custom designed program
blocks.
This is a subroutine that
consumes no additional
memory resources and canbe called multiple times.
Use a function orsystem function blocks,
thesystemwill
automatically handle theirconnection,
without
manual intervention.
The main purpose is tosave user-defined data.
It is used to hold data
related to the hardware
configuration.

2.4. Factory bus and terminal bus
Automated communication in factories depends on astable and efficient network infrastructure. In this context,
industrial Ethernet came into being, which follows the802.3 standard formulated by the International
Electrotechnical Commission (IEC) and becomes the key
technology to achieve factory automation communication.
This kind of network technology is often used as thetransmission medium in the construction of networkarchitecture, and is favored for its high stability and antiinterference.
Industrial Ethernet not only ensures a stable connection
between the factory bus and the terminal bus, but also
promotes seamless docking and data exchange between
different industrial communication protocols. For largescale industrial environments, especially those with strict
requirements for real-time and data transmission speed, thePCS7 system provides a high-speed and reliablecommunication solution by integrating industrial Ethernet
technology. The system, combined with advanced fiber
optic connectivity, marks a major advance incommunication technology for industrial automation. The
system adopts high-speed optical interconnection
equipment, which not only improves the data transmissionrate, but also ensures the security and reliability ofcommunication. With this technology, the PCS7 achieves
data transfer rates of up to 1Gbps, meeting the demand forhigh-speed communications in industrial environments.
In addition, the communication architecture of the PCS7
system supports a variety of transmission media, including
industrial twisted pair (ITP) and optical cable (FOC),
providing users with flexible network cabling options.
This diversity enables PCS7 to adapt to different industrialsite conditions, whether in environments with large
electromagnetic interference or scenarios requiring longdistance transmission, ensuring the stability and efficiency
of communication. By combining these technologies,
PCS7 provides a powerful and flexible communication
platform for modern industrial automation.

2.3. Operator station
In industrial control systems, the operator station (OSstation) plays an important role in the interaction between
the user and the production process, which is usually
implemented by computer systems. The design andconfiguration of these operator stations is done by theengineer station (ES station), so their function and setup is
an integral part of the ES station project. In a distributed
operating system environment, an operator station can bedivided into two basic components.
Operator station server: This component acts AS a hub
for data forwarding, transmitting real-time program values
to the connected operator station client, and is also
responsible for transmitting the display content of theoperation interface to the relevant functional modules of
the automation station (AS), ensuring real-time monitoring
and accurate control of the production process.
Operator station client: The client accesses the data onthe server through the data connection established with theserver, so that the operator can monitor the process andperform necessary control operations on the local orremote interface.
The design of operator stations focuses on the following
aspects, such as user interface design, functional
integration, field simulation display, data archiving andhistory. Through these designs, the operator station not
only improves the ability to monitor the production
195

3. Mathematical Modeling and Automatic
Operation of the Controlled Object

3.2. SFC block
In the process of running, the simulation system
automatically executes the sequence control program, uses
SFC to initialize the initial value of the control parameters
required by the whole control system, and executes eachcontrol loop in turn, which is shown in Fig. 2.
After setting the initial value, each control loop of thecontrol system automatically transitions to the stable
operation mode by executing the "END" step. The switch
on the operating panel allows the operator to fully control
the operating mode, that is, the operator can automaticallycontrol according to the preset control target value. Thisensures that after parameter initialization, all control loops
can smoothly enter the automatic control state, thus
realizing the automation and optimization of the process.

In PCS7, an engineering application, there are many ways
to construct mathematical models.
3.1. CFC block
Continuous function diagram (CFC) is an advanced
control strategy, which simulates the dynamic behavior of
the controlled object through the construction of function
blocks. These functional blocks include not only basic
control algorithms such as ratio (P), integration (I) anddifferentiation (D), but also advanced functions such as
delay and arithmetic operations, which have been
integrated and pre-programmed in the PCS7 controlsystem.
In the construction of object model, CFC block is used
to define the characteristics of the object, and operation
block is used to set and solve the relevant mathematicalformulas, and jointly complete the mathematical modelingof the controlled object. This approach allows us toaccurately model and predict the behavior of objects.
Taking the chemical reactor as an example, by referringto the experimental data and using the CFC module, wehave successfully established mathematical models for key
parameters such as liquid level, pressure, feed andtemperature. These models not only deepen ourunderstanding of the reactor mechanism, but also provide
a powerful tool for optimizing control strategies andimproving production efficiency.
1. Liquid level objects
Mainly: integral link and inertia link.
G(S)=

3.25
1+5.47S

*

2.13
0.97S

(3-1)

2. Objects of stress
Mainly: inertia link and integral link.
G(S)=

2.78
1+5.29S

*

0.91

5.58S

(3-2)

3. Feed flow
Mainly: the inertial link of its principal and subordinate
reactants.
G(S)=
G(S)=

1.87
1+5.49S
2.39(3-4）

1+4.68S

4. Temperature object
Mainly: the second stage of the lag time [2].
G(S)=0.6 ∗

1

4.29S

∗Fig. 2 Simulating the SFC starting sequence

(3-3)

1

3.93S

4. Design of Advanced Control Scheme forSimulation System of Chemical Reactor
In the experiment, PID controller in APL library of PCS7
is used to realize the precise control of the reactor. The(3-5）

196high-level control system decisions; The second is internal
generation, which is usually calculated by the PID
controller built into the system based on real-time process
data. The PID controller adjusts the system in real time byadjusting its ratio (P), integral (I) and differential (D)parameters to ensure the stability and accuracy of thecontrol process.
In order to achieve the best performance of the PID
controller, these parameters need to be precisely tuned.
The PID tuner is a specially designed tool that can
automatically or manually adjust the PID parameters
according to the dynamic characteristics and control
requirements of the system to achieve the optimal control
effect. The tuning process may include evaluation ofsystem response speed, stability, and overshoot, as well as
iterative optimization of PID parameters. In this way, thePID tuner helps ensure that the control system responds
quickly and accurately to changes in the setpoint SP1,increasing the efficiency and reliability of the overallsystem.
The liquid level control model, as shown in Fig. 4, isbuilt using the CFC block of PCS7.

control process covers several key parts such as feed,pressure, level and temperature.
The feed part is implemented by a simple proportional
module, which is divided into two sub-modules: the mastermodule and the slave module. The main module isresponsible for controlling the flow of the main reactant,while the flow of the auxiliary reactant is indirectlycontrolled by the set value of the main module. In addition,
the proportional controller provides two PID control loops
to independently regulate the catalyst portion of thereactant.
The pressure control part is handled by a separate PIDmodule. After setting the initial setting value, throughsimulation tests, we ensure that when the actual operating
value exceeds the preset range, the exhaust valve willautomatically start to release pressure; Conversely, if theoperating value is below the set value, the inert gas intake
valve will be opened to replenish the pressure until therequired process parameters are reached. The wholesystem adopts proportional-integral-differential control
method to achieve accurate feedback control of pressure.
The liquid level control part also adopts an independent
PID module to realize. Through these carefully designed
control strategies, we are able to ensure that the reactor
remains stable and efficient under a variety of operating
conditions.
In the temperature part, cascade control is used. The
inner ring of cascade control adopts PID module to control
the flow rate of hot and cold water valves to realize thecontrol of jacket temperature [3]. The output MV of a PID
module is adopted in the outer ring as the given value ofthe PID controller in the inner ring.
4.1. Liquid level control scheme
For the control of liquid level in the loop, a negative
feedback closed-loop loop is used, as shown in Fig. 3.

Fig. 4 Liquid level simulation objects
For these four parts, it is usually used in a user-definedclosed-loop control system set by users, integrating theinput values according to the ladder rule, and output theresults.
Fig. 5 shows the pipe diagram and function block of
the liquid level control loop. A control loop is provided in
the figure. The CFC block in Fig. 6.

Fig. 3 Pipes and devices
In the automatic control system, the set value SP1 is oneof the key parameters of the control process, which
determines the target state of the process control. The
value of SP1 can be obtained in two ways: one is external
input, which usually comes from operator instructions or197data block of PID function block. Through the simulation
test, we can obtain the ideal control data and apply thesedata to the controller to achieve the optimal adjustment
effect under various control modes.
A notable feature of this tool is its ability to provide asimultaneous real-time data curve display of initial,
median, and final values. This intuitive data display not
only helps the operator monitor the control process in realtime, but also clearly demonstrates the effect of the overall
optimization function. With this advanced tool, we canmore precisely adjust and optimize the control parameters
to ensure the stability and efficiency of the control system,
thus achieving our desired control effect.
Below, after proper PID tuning, the appropriate tuning
pattern is obtained, which is shown in Fig. 7.

Fig. 5 Pipes and functional blocks of the liquid level
control loop

Fig. 6 Connection structure of each CFC block in theliquid level control loop
In addition, for the feed flow, pressure, temperature
three parts, also to design the corresponding control
scheme. Among them, the feed part is controlled by ratio,
the pressure part is controlled by division, and thetemperature is controlled by cascade.
4.2. Tuning of controller PID parameters
In the automatic control system, it is very important to use
PID module to control the controlled object accurately.
Correct parameter setting is the key to achieve control
objectives. The experiment focused on the level control
loop and showed the results of 4 control loops.
We developed a PID tuner tool based on PCS7 software,
which can collect and record data through the background198

Fig. 7 Setting results of liquid level, flow rate,pressure, and temperature
References[1] Lee, K., & Park, S. (2021). "Model-based Temperature
Control of a Batch Reactor for PharmaceuticalProduction."
Industrial & Engineering Chemistry
Research,60(45),16705-16713.
doi:10.1021/acs.iecr.1c03152.
[2] Jiangtao Zhang, et al. "Research Progress on Temperature
Control of Chemical Reactor." Chemical Automation andInstrumentation 49.04 (2022): 419-423. doi:10.20030/j.
cnki.1000-3932.202204002.
[3] Zhao, X., & Liu, J. (2018). "PID Control Algorithm for
Steam Temperature in Power Plants." IEEE Access, 6,18685-18692. doi:10.1109/ACCESS.2018.2822133.

Authors Introduction
Mr. Hongshuo Zhai

He is a first-year master candidate inTianjin University of Science andTechnology.

199