Generalization of the Studies of Hydraulic and Thermochemical Operating Conditions in the Separation Devices, External Salt Compartments, and Circulation Loops of Thermal Power Plant Boilers

• Published in: Thermal engineering Vol. 68; no. 6; pp. 441 - 451
• Main Author: Fedorov, A. I.
• Format: Journal Article
• Language: English
• Published: Moscow Pleiades Publishing 2021; Springer Nature B.V
• Subjects: Blowdown; Boiler Auxiliary Equipment; Boilers; Burner Units; Compartments; Cyclones; Engineering; Engineering Thermodynamics; Evaporation; Heat and Mass Transfer; Heat recovery; Hydraulics; Power Plant Fuels; Power plants; Salt; Silicon dioxide; Silicon oxides; Sodium; Steam Boilers; Thermal power plants; Thermoelectricity; Water circulation; Water flow; drum boilers; process models; circulation loops; hydraulic and thermochemical operating conditions; separation and bubble-cap steam washers; mixing; pulsating circulation characteristics; external salt compartments; staged evaporation; salt ratio lines; turbulent diffusion; calculation procedures
• ISSN: 0040-6015; 1555-6301
• DOI: 10.1134/S0040601521060033

— The results of studying hydraulic and thermochemical operating conditions of thermal power plant drum boiler’s internals are presented. Data on the boiler water’s salt content are given for the salt compartment comprising two pairs of external cyclones per boiler side, which are connected to one waterwall. It is shown that the salt content in the distant (along the water flow) cyclone is a factor of three higher than it is in the nearby cyclone. It is found from studying the hydraulic and thermochemical operating conditions in the drums that, in order to exclude salt imbalances in the drum, the circulation loop feeding place and the steam–water mixture inlet should be spaced apart by no less than two to three longitudinal pitches between the downcomer tube rows. A procedure for calculating staged evaporation schemes with double-sided salt compartments is developed and experimentally verified. It is shown that the existing procedure does not reflect the real distribution of salt concentration in the evaporation stages. Results from studies of salt ratio lines are given, which made it possible to refine their calculation procedure and optimize the place of their connection to the boiler circulation loops. Based on the results from studies and mathematical modeling of physicochemical processes in the drum using the ANSYS Fluent software system, an efficient scheme of boiler internals without the use of bubble-cap steam washers is developed for the high-pressure drums of the PK-85 heat recovery steam generator, which made it possible to obtain high-quality steam in using feed water with a sodium content (Na) four times higher than its standardized value and with two times higher than normal content of silicon oxide (SiO 2 ) in boiler water during operation with a continuous blowdown rate up to 0.5–1.0%.