1. Product introduction
OHR-E300 series artificial intelligence thermostat/regulator adopts real artificial intelligence formula, the instrument starts the self-tuning function, and can automatically find the optimal parameters to achieve a good control effect according to the characteristics of the controlled object, without manual self-tuning parameters. The temperature control accuracy is basically ±0.1°C, without overshoot and undershoot, reaching the international advanced level. It can be used with various sensors and transmitters to realize the measurement and display of physical quantities such as temperature, pressure, liquid level, capacity, force, etc., and cooperate with various actuators to PID adjustment and control, alarm control, data acquisition and other functions of electric heating equipment and electromagnetic and electric valves. It is suitable for industrial furnaces, electric furnaces, ovens, test equipment, injection molding machinery, packaging machinery, food machinery, printing machinery and other industries.
Second, the working principle and solution
The configuration of the control system is shown in Figure (1).
The temperature control is realized by the OHR-E300 intelligent regulator, which has the advantages of small size, high reliability, strong anti-interference ability, etc., and has a variety of control methods for selection, with RS232/485 interface, which can constitute a small (DCS) distributed control system. The input of the instrument adopts a K-type thermocouple, the output adopts an SSR drive module, and the temperature control element adopts a 20A SSR solid-state relay. OHR-E700 16-point temperature detector is used for the internal temperature detection of the reactor, which can input thermocouple signals with a variety of index numbers, which can realize automatic cold junction compensation and self-stabilizing zero function. 4 pressure transmitters are selected for pressure detection, with digital display function.
In order to improve the reliability of the control system, automatic circuit breakers and fast fuses are added to the power supply circuit of each instrument. The instrument control cabinet is specially designed, all instruments and related parts, including the start and stop buttons of the metering pump, contactors, relays, etc., are assembled in the control cabinet, and the input and output signals of various instruments are connected to the field devices through the common terminals, and the control system has a complete set of characteristics.
Commissioning and operation of the control system
Because the system has many temperature control loops, which is the main control parameter, the constant temperature control accuracy is required to be high, and the temperature is not allowed to overshoot during the test. To this end, the scheme of controlling the wall temperature of the reactor to detect the internal temperature is adopted, which can reduce the pure hysteresis of the control object, so as to achieve the required temperature control accuracy. OHR-E300 intelligent regulator provides five kinds of adjustment methods, the debugging first adopts the self-tuning parameter function, after 1~2 times of self-tuning process, most of the control loops meet the requirements, for individual control loops that can not meet the requirements, using OHR artificial intelligence adjustment, the parameters that need to be tuned are P, I, D, T1, because the characteristics of each section of the reactor heater are basically the same, so the range of individual control loop selection parameters is P=680~760,I=25~33,D=200~300, T1=0, the constant temperature control accuracy is less than ±0.7 °C, and the maximum overshoot is less than 1 °C, and satisfactory results have been obtained. For the debugging of gas flow control and pressure detection instruments, as long as the debugging is carried out according to the instructions for use, it is easy to meet the actual requirements.
The functions of the control system are as follows:
(1) Process flow display and real-time control and parameter display of each measurement and control point;
(2) Parameter setting and modification. All kinds of measurement and control parameters, high and low limit alarms, real-time data storage time, timing printing time, etc. can be set and modified by the keyboard through the human-computer interaction interface;
(3) Data reports, including shift reports, daily reports, monthly reports and other forms of statistical reports, can be displayed or printed;
(4) Data storage and historical curve printing. The main measurement and control parameters can be saved regularly, and the data can be continuously stored for 3 months, and the corresponding historical curves can be printed according to the stored data display;
(5) Overrun alarm. When the parameter with the alarm limit is set to exceed the limit alarm, the parameter at the corresponding position of the screen flashes and gives an audible prompt, and the alarm parameter and time are printed at the same time.
OHR-E300
III. Concluding remarks
The advantages of using OHR intelligent regulator and industrial control system are high reliability, low failure rate, high measurement and control accuracy, and it is suitable for long-term continuous operation of industrial sites. Due to the use of (DCS) distributed structure, the detection and control of small devices are completed by instruments, and the process management is realized by industrial computers. When the industrial computer fails, only the computer management and data display and recording functions are affected, and the field instrument can still be detected and controlled normally; when an instrument fails, the instrument only needs to be processed separately, and other control loops are not affected, which greatly improves the reliability of the control system.
OHR-E700