Plant monitoring apparatus

A plant monitoring apparatus comprising:

• an arithmetic processor configured to calculate, as a limit value, in time series, at least one of an upper limit value, a lower limit value having a value smaller than the upper limit value, an upper-upper limit value having a value larger than the upper limit value, and a lower-lower limit value having a value smaller than the lower limit value based on a second process value obtained in time series from a second point associated with a first point and different from the first point in a plant;
• circuitry configured to compare a first process value acquired in time series from the first point of a monitoring target in the plant and the limit value corresponding to the first process value to determine a point in time when the first process value exceeds the limit value;
• and
• a display processor configured to cause a display device to display, in time series, the first process value within a time range decided based on the point in time obtained by the circuitry and the limit value corresponding to the first process value, wherein
• the circuitry determines whether the first process value acquired in time series exceeds and deviates from the limit value corresponding to the first process value or recovers from a state in which the first process value deviates from the limit value to a state in which the first process value does not deviate from the limit value, the circuitry further generating a warning message associated with occurrence time when the state in which the first process value deviates from the limit value occurs and an occurrence message and a warning message associated with recovery time when the first process value recovers from the state in which the first process value deviates from the limit value to the state in which the first process value does not deviate from the limit value and a recovery message,
• the plant monitoring apparatus further comprises:
• a warning screen display circuitry configured to
• cause the display device to display a warning screen on which the warning messages are listed in time series in order of generation;
• indicate any one of the warning messages on the warning screen;
• and
• output information based on time associated with the indicated
• warning message to the display processor, and
• the display processor causes the display device to display, in time series, the first process value and the limit value corresponding to the first process value within the time range including the time in information input from the warning screen display circuitry.