Purpose of APC
Automatic process control system (APCS) of pretreatment section is designed for reaching high efficiency of process equipment operation by following process procedures, improving end product quality and reducing its prime cost.
Main Operation Modes
There are three main operation modes of APCS:
Manual operation mode of APCS - the operator directly controls the controller position (judging from the actuator status) based on the real-time control data being input by the input hardware at the operator's station.
Automatic operation mode of APCS - the operator controls and monitors the way the process equipment being operated automatically works (including that under regulator control), and the way the process goes. The set mode maintanance is performed by a complex of system hardware and software (CSHS) either automatically or under control of the upper level control system.
Remote operation mode of APCS - from the place of operator's control of the system, the operator forms instructions and tasks required for stabilizing or changing parameter of process mode as well as for preventing and localizing accidents and emergency situations. Besides, the operator controls and monitors operation of process equipment and the way the process goes.
Hardware and Software Complex of APCS
The hardware and software complex of APCS comprises the following:
Output signals of sensors and primary transducers of process parameters refer, as a rule, to continuous electrical
signals of direct current 4-20 mA.
Output signals of sensors for major equipment condition refer to electrical discrete-time signals which equal to 24V or ~ 220V.
Output signals of the controller for actuators control refer to continuous electrical signals of continuous current 4-20 mA.
Output signals of actuator control refer to continuous electrical signals which equal to 24V or electrical discrete-time signals = 24V or ~ 220V.
Network communication is accomplished by using standard TCP/IP protocol.
Data exchange between the system components is performed automatically.
Interconnections of APCS
APCS interconnections work as follows:
In cases provided within the control program, according to the set algorithms, APCS conducts survey of sensors and actuators informing the operator about their status. For safety reasons, in the event of emergency, transition of mechanisms to the state of “EMERGENCY” is recorded by the system, is archived, and after that the message with description of the reason is displayed.
Schematic diagram of automatic process control system of boiler house