Kontrolované chlazení pro plynulé lití

Controlled Cooling in Continuous Casting

článek v časopise - ostatní, Jost

en

Cooling is an essential part of the continuous casting technology. The new generation of mist nozzles allows controlling the cooling intensity in wide range by setting a combination of water and air pressures. The paper presents experimental method for measurement of heat transfer parameters of typically used water and water-air (mist) nozzles. The experimental apparatus uses the identical spray conditions to the conditions in plant. The nozzles are tested for pressure setting, for influence of casting speed, for behaviour in the overlapping areas. The tests provide the description of heat transfer coefficient and heat flux distribution on the cooled steel surface. The knowledge of these parameters is necessary for any advanced control system. Another area where the knowledge of cooling parameters is necessary is design of cooling sections for casting machine and preparation of cooling model for steel groups. The paper presents new experimental findings in specification of the Leidenfrost temperature that is sharp surface temperature border between high and low temperature regions where great difference in cooling intensity is observed. The paper also deals with the problems of homogeneity of cooling along the nozzle spray angle and in the overlapping area where thermal strips occur. Sensitivity of this problem to the pressure of coolant is discussed.

Chlazení je základem u technologie plynulého lití. Nová generace trysek umožňuje kontrolu intensity chlazení ve velkém rozsahu pomocí zadání kombinací tlaků vody a vzduchu. článek představuje experimentální metodu pro měření parametrů přenosu tepla s použitím klasických vodnícj a vodovzdušných trysek. Experimentální přístroj používá stejné podmínky ostřiky , které jsou použity ve skutečnosti. Trysky jsou testovány pro zadání tlaku, vlivu rychlosti lití a chování oblastí překryvu. Testy poskytují popis koeficientu přenosu tepla a rozvádění tepelného proudu na chlazený ocelový povrch.

Cooling is an essential part of the continuous casting technology. The new generation of mist nozzles allows controlling the cooling intensity in wide range by setting a combination of water and air pressures. The paper presents experimental method for measurement of heat transfer parameters of typically used water and water-air (mist) nozzles. The experimental apparatus uses the identical spray conditions to the conditions in plant. The nozzles are tested for pressure setting, for influence of casting speed, for behaviour in the overlapping areas. The tests provide the description of heat transfer coefficient and heat flux distribution on the cooled steel surface. The knowledge of these parameters is necessary for any advanced control system. Another area where the knowledge of cooling parameters is necessary is design of cooling sections for casting machine and preparation of cooling model for steel groups. The paper presents new experimental findings in specification of the Leidenfrost temperature that is sharp surface temperature border between high and low temperature regions where great difference in cooling intensity is observed. The paper also deals with the problems of homogeneity of cooling along the nozzle spray angle and in the overlapping area where thermal strips occur. Sensitivity of this problem to the pressure of coolant is discussed.

Continuous casting Cooling…..Heat transfer…..Experimental method

2004

14.09.2004

Chinese Society for Metals

Peking

0449-749X

The Chinese Society for Metals

Chinese Society for Metals

39

2004

1

342–346

5