Common faults and analysis steps of automatic instruments in refineries
1. Common faults and analysis steps of temperature instruments
There are three common faults in temperature instruments:
(1) The temperature rises sharply: it is mainly caused by the open circuit of the thermocouple, loose terminals, broken wires, temperature failure, etc. Such faults are mainly caused by the destruction of the instrument system;
(2) Sharp decrease in temperature: mainly caused by short circuit of thermocouple, short circuit of wire and temperature failure;
(3) When the temperature fluctuates greatly or oscillates rapidly, this type of fault is mainly caused by the operator's improper adjustment of the parameter PID.
Steps to analyze common faults of temperature instruments: If check whether the input signal of the control valve has changed, the input signal has not changed, but the control valve shows a very obvious action, indicating that there is a problem with the diaphragm head of the control valve; if check the control valve. Whether the input signal of the positioner has changed, the input signal has not changed, but the output signal has changed, indicating that the positioner of the regulating valve is faulty; check the change of the data information generated by the input signal of the positioner, and then check the regulator. Whether the signal outputted to the outside has changed, if the regulator does not produce the expected change, and the output information has changed, it means that the regulator itself has a fault problem. Common failures of temperature instruments will affect the judgment of production workers on the temperature of the refinery, resulting in the refinery not meeting the specified temperature standards, thus causing safety problems in the operation of various functions and machines of the refinery.
2. Common faults and analysis steps of pressure instruments
The common faults of pressure instruments generally have the following two points:
(1) The pressure value suddenly decreases or increases or the indication curve of the pressure instrument does not change;
(2) The pressure fluctuation is relatively large, and there is a large vibration or a dead line.
Analysis steps for common faults of pressure instruments: If the pressure value fluctuates greatly and there is a large vibration, first check whether the staff has improper operation, or whether the PID parameters of the regulator have been adjusted well; if the pressure instrument appears In the case of a dead line, it is necessary to check whether the pressure measurement system is faulty. First, measure whether the pressure guiding catheter system is blocked, and then check whether the system output by the pressure transmitter changes. If there is a change, it indicates that the controller measures the indication There is a problem with the system. The oil refinery is a high-risk work that operates in a high temperature and vacuum environment. The pressure instrument is one of the important instruments for judging the air value. The failure of the pressure instrument will affect the working environment of the oil refinery. In severe cases, it will inevitably occur. Major disaster accident.
3. Common faults and analysis steps of flow meters
The common faults of flow meters generally have three points:
(1) The flow indication value is extremely small;
(2) The flow indication value is extremely large;
(3) The flow fluctuates greatly.
Analysis steps for common faults of flow meters: If the data displayed by the flow indication value is extremely small, first check whether the on-site detection instrument is normal. If the display is normal, it proves that the display instrument is faulty. If the data indicated by the on-site detection instrument also shows The minimum value, check the opening and closing degree of the air regulating valve. The opening and closing degree of the regulating valve is zero, which proves that there is a fault between the regulating valve and the regulator, and the opening degree of the regulating valve is normal. etc.; if the indication value of the flow meter is very large, the indication value of the detection instrument is usually the largest. In this case, the air regulating valve can be adjusted manually. If the flow value can be lowered, it proves that there is a problem with manual operation; if the flow rate The numerical value of the instrument shows that the flow fluctuates greatly, indicating that it is a problem with the instrument or because the PID parameter control is not reasonable enough.
The three most important data values in an oil refinery are flow rate, temperature and pressure. After collecting these three types of data, the energy data of the refinery can be accurately calculated, so as to judge whether its operation is normal, and timely take care of the abnormal situation. out adjustment.
