Estimation of the Falling Heat Flow and Determination of Safe Distances During Oil Fires in Class I Tanks

This article examines the pressing issue of determining safe distances during a fire in a 50,000 m³ vertical steel oil tank under typical winter conditions, taking into account wind loads. This study was conducted against the backdrop of increasingly frequent drone attacks on fuel and energy facilities, creating a real potential for major fires with the risk of cascading accidents. An analysis of statistical data and current threats substantiates the need to refine regulatory approaches to assessing thermal impact. Calculations of incident heat flux were performed using the methodology of Order № 533 of EMERCOM of Russia «On the approval of the methodology for determining the calculated values of fire risk at production facilities», and CFD modeling was conducted using Fire Dynamics Simulator (FDS). It was established that the methodology of Order № 533 of EMERCOM of Russia systematically overestimates distances to threshold values: in the near zone (up to 20 m) by 1,4–2,1 times, and at a distance of 40–50 m – by 5–6 times. The main reason is the idealized cylindrical model of the flare, which does not take into account the elevation of the combustion source (wall height 17,8 m) and the associated shading. It was established that comparing two calculation approaches without using in-kind data only allows one to assess their discrepancies, not their absolute accuracy. Two approaches to tactical planning were proposed: a normative (conservative) approach and a risk-based approach (using refined heat flow fields). Safe distances for personnel and the required cooling water flow rates were calculated. The feasibility of experimental validation of CFD models for developing recommendations for reducing safe distances was confirmed.