An apparatus for supplying molten steel and a continuous casting method therewith are described. The SCR analysis module estimates an ammonia slip rate downstream of an SCR catalyst, an NH3 conversion rate, an NH3 supply rate, and an NH3 oxidation rate. A first stent is associated with the main portion and is expandable from a first configuration to a second configuration to retain the main portion in position within the target vessel. The output port is coupled to the receiving port, and the capacitive component in the circuit unit and the inductive component in the signal transmitting circuit form a resonator structure configured to operate in a frequency resonance mode during the reception mode. The primary and secondary washing units share certain system resources during an overall washing operation, with the primary washing unit having preference over the secondary washing unit.