A technology for removal of undissolved impurities from a horizontal steam generator using purge water is developed on the basis of a theoretical analysis. A purge with a maximal flow rate is drawn off from the zone with the highest accumulation of sludge in the lower part of the steam generator after the main circulation pump of the corresponding loop is shut off and the temperatures of the heat transfer medium at the inlet and outlet of the steam generator have equilibrated. An improved purge configuration is used for this technology; it employs shutoff and regulator valves, periodic purge lines separated by a cutoff fixture, and a D y 100 drain union as a connector for the periodic purge. Field tests show that the efficiency of this technology for sludge removal by purge water is several times that for the standard method.
A theoretical substantiation and the results of experimental studies of the behavior of impurities in the volume of the boiling medium in equipment in nuclear power and heat-and-electricity plants are presented. It is hypothesized that coarsely dispersed sludge accumulates at the boundary of the turbulent nucleus and viscous sublayer and only a small part of it settles on the heat-transmitting surface. If this hypothesis is correct, then sludge should accumulate and be expelled into the main volume of the working medium when the heat load changes, just like soluble impurities. The experimental data confirm this hypothesis.The quantity of impurities entering modern steam-generating facilities in nuclear power and heat-and-electricity plants is now always greater than the quantity leaving with steam, moisture, and purge water. Therefore, impurities either settle on a heat-transmitting surface or accumulate in the steam-generating volume. To understand the distribution of the different impurities, we present the following classification:macrodistribution -the distribution of impurities over the volume of the working medium; for drum boilers in heatand-electricity plants it is the distribution over the length of the drums; microdistribution -the variation of the impurity content in the boiling layer at the wall. The impurities brought into the steam-generating equipment could be easily soluble in water and insoluble in steam, easily soluble in water and steam, and insoluble in both water and steam.The macrodistribution of water-soluble and steam-insoluble impurities have been studied in greatest detail. A typical example is the behavior of sodium salts (phosphate water softening of boiler water in drum boilers). It follows from the elementary equations of the material and salt balances that the concentration of such an impurity is determined by the relationwhere S imp and S f.w are the concentration of the impurity in the purge and feed water, respectively, mg/mg; P = G imp /G 0 is the relative purging (ratio of the purging flow rate to the steam capacity). Expression (1) does not always hold. Thus, if the purge point is not optimized, then zones where the impurity concentration is higher than in the purge water can arise in the volume of the boiling working body.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.