By using steel plates with radiation-proof material coating welding on conventional ladle exterior shell and lid

a new ladle with vacuum shell is got to reduce heat loss

and the effect of pressure in vacuum chamber (50~10

5

Pa) on temperature reduction of 1873K 500kg liquid steel and the comprehensive thermal transmission mechanism in vacuum chamber are studied by using vacuum thermal insulation theory. Results show that as the absolute pressure in chamber of ladle shell and lid is respectively 50Pa and 10

5

Pa for 30min

the temperature drop of liquid in ladle is respectively 8K and 37K

and the conversion convection additional factor value at 10

5

Pa is 200 times as much as that at 50Pa； the thermal conductivity of insulated layer of conventional ladle is 11 times as much as that of vacuum shell ladle with vacuum chamber absolute pressure 50Pa

and the thermal c

onductivity of working layer refractory materials of conventional ladle is 116 times as much as that new ladle with 50Pa. Therefore

the new ladle with lower pressures in shell has obvious thermal insulation effect.