Thermochemical gas analyzer readiness assessment model

Introduction. The importance of fire safety (FS) measures at fuel and energy industry facilities, in particular over the course of continuous technological processes of oil refineries (OR), is highlighted in the article. Decision makers are able to manage the process of planning and implementing these measures thanks to special software integrated into automated process control systems. The fire and explosion prevention subsystem designated for managing gas analyzing equipment and its control processes was chosen as the object of research. Theoretical framework. The fire safety of oil refineries, that entails the maintenance of gas analyzer sensors, is characterized by such random subprocesses as climate and weather changes at refineries. It is proposed to split this process into two opposite subprocesses, destructive and productive ones. Events related to calibration, verification or replacement of sensitive elements of thermochemical sensors are at the core of the recovery subprocess. Destructive subprocess events are associated with the appearance of deviations in thermochemical sensors from nominal values as registered by a shift on duty. It is proposed to describe the randomness of this subprocess as a Markov process. The sensor system behavior is simulated as the two streams. Thermochemical sensors have two modes: ready and not ready. Research results. The readiness model of gas analyzers is calculated as a ratio of the number of thermochemical sensors which are potentially ready for use in accordance with the regulatory and engineering documentation, to their total number, taking into account the randomness of events that make thermochemical sensors unready. A special case used to illustrate the Markov model building is studied. The possible number of modes for sets of thermochemical sensors is calculated for such a situation. The transition between modes of sets in a fire alarm subsystem is determined using the proposed system of differential Kolmogorov equations, which has five equations for a specific case. The calculation can be generalized for any number of remote sensors. Conclusions. The readiness assessment method applied to thermochemical sensors of gas analyzers in open areas of refineries is studied. The method can be applied in the process of automated fire and explosion prevention system operation.