Development of Hard Secondary Cooling by High-pressure Water Spray in Continuous Casting

Abstract

Cooling intensity in secondary cooling is an important factor for achieving high-speed casting. In this study, we investigated the effects of the hydraulic pressure and water flow rate of a cooling water spray on cooling intensity, and developed a more efficient secondary cooling system with a high-water pressure spray. In laboratory experiments, a test plate was heated to 1 273 K and then cooled below a certain temperature by one nozzle under various experimental conditions. The heat transfer coefficient was estimated using the temperature data from thermocouples 3 mm below the cooled surface. The average heat transfer coefficient with a hydraulic pressure of 5 MPa was 2.8 times larger than that of a conventional water spray nozzle at the same water flow rate. On the basis of the laboratory results, plant trials were carried in the Kurashiki No. 2 CCM at JFE West Japan Works. A high-pressure water supplying device (maximum 5 MPa) with high pressure type nozzles was installed in one segment at a position from 2.5 to 4.0 m below the meniscus and the water flow rate of the high-pressure spray was the same as that of the conventional one. It was confirmed that casting speed was increased by 30% without any inner cracks or surface cracks for several steel grades. In addition, the measurements of slab surface temperature were in good agreement with the thermal calculation results from the laboratory heat transfer coefficient data.

Effects of Using New Mold and Modified Secondary Cooling Scenario on Continuous Casting Process at a Steel Plant in Turkey

“…In addition to mold properties, the operation parameters in secondary cooling at which the solidification of strand finishes are also very crucial to improve product quality and process speed [3,4,[20][21][22][23][24][25]. Reaching higher casting speeds is possible with suitable mold design and optimization of secondary cooling region [3,4,7,[16][17][18][19][20][21][22][23][24][25]. Utilization of high casting speeds in continuous casting operations is especially important to enhance productivity via increasing production rate in a steel plant [11,13,14,26,27].…”

Laboratory Experimental Setup and Research on Heat Transfer Characteristics during Secondary Cooling in Continuous Casting

“…Those papers discussed heat transfer during spray cooling and optimization of the cooling process. Ito et al [11] also investigated the effects of the hydraulic pressure and water flow rate of a cooling water spray on cooling intensity and developed a more efficient secondary cooling system with a high-pressure water spray. Tsutsumi et al [12] did laboratory experiments on the cooling capacities of hydraulic and mist spray cooling by several kinds of spray nozzles.…”

Velocity Characteristics of Air-mist Jet during Secondary Cooling of Continuous Casting Using PIV and LDV

“…To optimize heat transfer conditions at the hot interface, researchers must experimentally investigate nozzle performance with its cold characteristics. Many reports have been published regarding nozzle characteristics of air-mist jets, [2][3][4][5][6][7] such as the influence of nozzle design, 2) procedure on nozzle flow, 3,4) cooling intensity, 5) the fluid dynamics of air mist, 6) size and velocity characteristics of droplets 7) and so forth. The flow characteristics of the air-mist jets were experimentally identified with respect to the droplet size and velocity distribution, spray cone angle, and breakup length.…”