INVESTIGATION OF THE SLAGS ACCUMULATION MECHANISM IN LEAD-CONTAINING COOLANTS LOOPS AND ITS PREVENTION BY HIGH-TEMPERATURE TREATMENT WITH HYDROGEN AND WATER STEAM MIXTURES

Abstract

The results of computational and experimental studies of the properties of lead and lead-bismuth coolants and the mechanism of physicochemical processes occurring in their circulation circuits explain the reasons for the formation of slag deposits based on lead oxide. First of all, this is the uncontrolled interaction of lead and lead-bismuth coolants with gaseous oxygen, which, along with nitrogen, is one of the main components of air. Slag deposits are based on lead oxides, but they also contain a significant amount of unoxidized lead (and bismuth in the case of using a lead-bismuth coolant) bound by a lead oxide framework into a single structure, as well as a small amount of components of construction materials (iron , chrome, nickel). The formation of slags in the circulation loop with a lead-containing coolant has a negative effect on its operation: the flow cross-sections are narrowed; heat transfer surfaces are blocked; the normal operation of pipeline fittings is disrupted. To minimize slag accumulation, it is necessary to limit the contact of the coolant with air oxygen, avoid draining the coolant from the circulation circuit, control whether the circulation circuit is in a depressurized state both during research and during non-working periods, when heating and filling the circuits with a coolant, create and maintain a vacuum. The best way to prevent slag accumulation is periodic hydrogen cleaning of the circuit with gas mixtures "hydrogen - water vapor - inert gas". The greatest cleaning efficiency is achieved when gas mixtures are introduced directly into the coolant flow using gas injection devices. Mechanical devices with moving parts, ejectors, nozzle nozzles can act as gas injection devices.