Consists of Chemical automation, Chemical automation introduction, subsystem of automation, chemcial process automation
I What is chemical automation
1.1 Type
Chemical automation is a special form of industrial process automation, which focuses on the automatic control of chemical processes.
1.2 Feature
Chemical automation technology can ensure the normal operation of chemical reactions, optimize production processes, and improve product quality and yield.
1.3 Tehcnologies
The core technologies of chemical automation include feed control, reaction control, temperature control, concentration control, pH control, etc.
II Automatic control
2.1 Definition
Automatic control is to make the whole production process or working machinery (the controlled object) automatically operate according to predetermined rules, or to make a certain parameter (the controlled parameter) change according to predetermined requirements by using additional equipment or devices without direct participation of people.
2.2 Controlled object:
production equipment
2.3 Automation device:
Transmitter, controller, and actuator.
2.4 System
In order to realize the automation of chemical production process, the system generally includes the subsystems:
Automatic detection,
Automatic protection,
Automatic operation,
Automatic adjustment
2.4.1 Automatic detection system
P, Q, T, H detection
The system uses various sensors (liquid level meter, flow meter, pressure meter, etc.) and transmitters together to form automatic control monitoring signal source.Measurement, indication or recording of main process parameters is called automatic detection system.It replaces the operator's continuous observation and recording of process parameters, so it plays the role of human eyes.
For example, the heat exchanger uses steam to heat the cold liquid. Whether the temperature of the cold liquid after heating meets the requirements can be measured, indicated and recorded by a temperature measuring element equipped with a balance bridge;
The flow rate of cold liquid can be detected by orifice flowmeter.
Steam pressure can be indicated by pressure gauges. These are automatic detection systems.
There are two main tasks of automatic detection:
one is to directly measure and display the measured parameters to tell people or other systems about the changes of the measured objects, that is, automatic detection or automatic testing in general;
The other is used as the front-end system of the automatic control system. To help implement automatic control, which is to make corresponding control decisions according to the parameters changes.
2.4.2 Automatic protection system
Automatic protection system's full name is automatic signal and interlocking protection system: protection and control of parameters
In the production process, sometimes due to the influence of accidental factors, the process parameters exceed the allowable range of change and abnormal conditions occur.
For this reason, automatic signal interlock devices are often provided for certain critical parameters.
When the process parameters exceed the allowable range, the signal system will automatically send out acousto-optic signals to warn the operators and take timely measures before the accident is about to occur.
If the working condition has reached a dangerous state, the interlocking system will immediately and automatically take emergency measures, open the safety valve or cut off some passages, and stop the emergency if necessary to prevent the occurrence and expansion of the accident.
It is a safety device in production.
For example, if the reaction temperature of a reactor exceeds the allowable limit value, the automatic signal system will send out sound and light signals to alarm the process operators to deal with production accidents in time.
Due to the intensification of the production process, it is often impossible to deal with accidents by operators, because in an intensified production process, accidents often occur within a few seconds, and it is simply too late for operators to deal with them directly.
Automatic interlock protection system can solve this kind of problem satisfactorily, such as when the reactor temperature or pressure into the dangerous limit, the interlock system can immediately take emergency measures, increase the cooling dose or close the feed valve, slow down or stop the reaction, so as to avoid explosion and other production accidents.
2.4.3 Automatic operate system
This is programmed control.
Automatic Operate System can automatically perform certain periodic operations on production equipment according to predetermined procedures.
For example, the gas generator in the ammonia synthesis workshop requires periodic connection of air and water vapor according to the steps of blowing, blowing up, blowing down, gas making, blowing, etc.
The automatic control machine can replace the operator to automatically pull the valves of air and water vapor according to a certain time program, so that they are alternately connected to the gas generator, thus reducing the repetitive physical labor of the operator.
2.4.4 Automatic Adjustment System
Automatic Adjustment System is also called Follow-up Control System , Automatic Tracking System, and Fixed Value Control System.
It could keep the parameters in a certain range.
It is impossible for all kinds of technological conditions in the production process to be static.
Especially in chemical production, most of them are continuous production, and each equipment is interrelated. When the process conditions of one of them change, some parameters in other equipment may fluctuate more or less, deviating from normal process conditions.
For this reason, it is necessary to use some automatic adjustment devices to automatically control some key parameters in production, so that they can automatically control and return to the specified value range when they deviate from the normal state due to external interference (disturbance).This is the automatic adjustment system.
2.5 The tasks of above Subsystems.
Automatic detection system can complete the task of "knowing" the production process;
The signal interlock protection system can take safety measures to avoid production accidents when the process conditions enter a certain limit state;
The automatic control system can only perform certain periodic operations according to predetermined procedures;
The automatic adjustment system can automatically eliminate the influence of various interference factors on the process parameters, so that they are always maintained at the predetermined values, and ensure that the production is maintained in a normal or better process operation state.
Through the automatic regulation system, various detection instruments such as external clamping ultrasonic flowmeters and automatic control equipment can form a closed-loop feedback, and finally form a complete automatic production process.
Industrial process automation refers to the automatic control of various production equipment in the production process to make the production process more efficient and accurate.This technology can reduce manual intervention, improve production efficiency, reduce production costs, improve product quality, and ensure product consistency and reliability.Industrial process automation technologies include robotics, PLC, SCADA, etc.
With the constant needs of customers and technological progress, especially in the field of chemical process control non-standard customization characteristics, more and more chemical process automatic control requirements become customer concerns.WHGCM cooperates with many universities in China including Harbin Institute of Technology and Shandong University to develop laboratory, pilot and industrial reactor systems that meet customer automation needs and are well received by customers.
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