APPARATUS FOR ALWAYS STABLY MAINTAINING FURNACE PRESSURE BY AUTOMATICALLY CONTROLLING SUPPLY FLOW RATE OF ATMOSPHERIC GAS INTO BRIGHT ANNEALING FURNACE DURING CHANGE OF ATMOSPHERIC GAS

摘要

PURPOSE: To provide an apparatus for automatically controlling supply flow rate of atmospheric gas into a bright annealing furnace even during density change of the atmospheric gas according to change of mixing ratio of hydrogen to nitrogen according to steel types, thereby always maintaining furnace pressure in the stabilized state to improve surface quality of strip, reduce cost and prevent large facility accident. CONSTITUTION: The apparatus for controlling stabilization of bright annealing furnace pressure during atmospheric gas change comprises a furnace pressure monitoring part for determining whether pressure by a furnace pressure detection manometer(14) is a preset upper limit value(SV1) or more, or a preset lower limit value(SV2) or less; a set value smooth part for slowing changing a set gas concentration value(SV3) during a preset required change time(ST) when a furnace pressure change signal is inputted from the furnace pressure monitoring part; a set value change detection part for detecting decrease and increase of the set gas concentration value using an output signal of the set value smooth part; a furnace pressure set value selection part for selecting the set gas concentration value or the output signal of the set value smooth part according to a detection signal of the set value change detection part and a detection signal of the furnace pressure monitoring part; a furnace pressure controller(150) for controlling a nitrogen flow rate control valve according to a deviation value between the set value selected by the furnace pressure set value selection part and detection values; a cooling section flow rate set value selection part for selecting any one value out of a multiplication value obtained by multiplying a value(SV12) for compensating cooling section atmospheric gas flow rate set value during furnace pressure increase by a cooling section atmospheric gas flow rate set value(SV11), a multiplication value obtained by multiplying a value(SV13) for compensating cooling section atmospheric gas flow rate set value during furnace pressure decrease by the cooling section atmospheric gas flow rate set value, and the cooling section atmospheric gas flow rate set value according to monitoring results of the furnace pressure monitoring part; a cooling section flow rate controller for controlling a nitrogen cooling section atmospheric gas flow rate control valve according to a deviation value between the set value selected by the cooling section flow rate set value selection part and detection values; a heating section flow rate set value selection part for selecting any one value out of a multiplication value obtained by multiplying a heating section atmospheric gas flow rate value during furnace pressure increase(SV22) by a heating section atmospheric gas flow rate set value(SV21), a multiplication value obtained by multiplying a heating section atmospheric gas flow rate value during furnace pressure decrease(SV23) by the heating section atmospheric gas flow rate set value, and the heating section atmospheric gas flow rate set value according to monitoring results of the furnace pressure monitoring part; and a heating section flow rate controller for controlling a nitrogen heating section atmospheric gas flow rate control valve(VL3) according to a deviation value between the set value selected by the heating section flow rate set value selection part and detection values.