Waste heat recovery structure for steel making electric arc furnaces, steel making electric arc furnace facility, and waste heat recovery method for steel making electric arc furnaces

A steel making electric arc furnace facility comprising a plurality of steel making electric arc furnaces, and a waste heat recovery structure configured to recover waste heat as saturated steam from exhaust gas discharged from the steel making electric arc furnaces and to turn the saturated steam into superheated steam by subsequent heating,

• the waste heat recovery structure comprising:
• a first exhaust gas flow path provided to each of the steel making electric arc furnaces to discharge exhaust gas thereinto;
• a waste heat boiler disposed on the first exhaust gas flow path and configured to recover waste heat as saturated steam from exhaust gas;
• a steam accumulator configured to store steam formed by confluence of saturated steam parts, each generated by the waste heat boiler;
• a steam super heater configured to turn steam, which has been stored in the steam accumulator, into superheated steam by heating;
• a second exhaust gas flow path configured to lead exhaust gas, which has been treated with waste heat recovery in the waste heat boiler, to the steam super heater to use the exhaust gas for superheating saturated steam and to then discharge the exhaust gas;
• a third exhaust gas flow path configured to discharge exhaust gas, which has been treated with waste heat recovery in the waste heat boiler, not through the steam super heater;
• and
• a switching device configured to switch flow paths for exhaust gas, which has been treated with waste heat recovery, between the second exhaust gas flow path and the third exhaust gas flow path.

A waste heat recovery structure for a plurality of steel making electric arc furnaces, which recovers waste heat as saturated steam from exhaust gas discharged from the steel making electric arc furnaces and turns the saturated steam into superheated steam by subsequent heating, the structure comprising:

• a first exhaust gas flow path provided to each of the steel making electric arc furnaces to discharge exhaust gas thereinto;
• a waste heat boiler disposed on the first exhaust gas flow path and configured to recover waste heat as saturated steam from exhaust gas;
• a steam accumulator configured to store steam formed by confluence of saturated steam parts, each generated by the waste heat boiler;
• a steam super heater configured to turn steam, which has been stored in the steam accumulator, into superheated steam by heating;
• a second exhaust gas flow path configured to lead exhaust gas, which has been treated with waste heat recovery in the waste heat boiler, to the steam super heater to use the exhaust gas for superheating saturated steam;
• and
• an operation section configured to operate the steel making electric arc furnaces to sequentially perform respective running operations by staggering the running operations with a predetermined deviation time,
• wherein the operation section sets the deviation time to minimize changes over time in the number of running furnaces of the steel making electric arc furnaces.

A waste heat recovery method for a plurality of steel making electric arc furnaces, by use of a waste heat recovery structure that includes a first exhaust gas flow path provided to each of the steel making electric arc furnaces to discharge exhaust gas thereinto;

• a waste heat boiler disposed on the first exhaust gas flow path and configured to recover waste heat as saturated steam from exhaust gas;
• a steam accumulator configured to store steam formed by confluence of saturated steam parts, each generated by the waste heat boiler;
• a steam super heater configured to turn steam, which has been stored in the steam accumulator, into superheated steam by heating;
• and a second exhaust gas flow path configured to lead exhaust gas, which has been treated with waste heat recovery in the waste heat boiler, to the steam super heater to use the exhaust gas for superheating saturated steam,
• the method comprising:
• operating the steel making electric arc furnaces to sequentially perform respective running operations by staggering the running operations with a predetermined deviation time, wherein the deviation time is set to minimize changes over time in the number of running furnaces of the steel making electric arc furnaces.

A steel making electric arc furnace facility comprising a plurality of steel making electric arc furnaces, and a waste heat recovery structure configured to recover waste heat as saturated steam from exhaust gas discharged from the steel making electric arc furnaces and to turn the saturated steam into superheated steam by subsequent heating,

• the waste heat recovery structure comprising:
• a first exhaust gas flow path provided to each of the steel making electric arc furnaces to discharge exhaust gas thereinto;
• a waste heat boiler disposed on the first exhaust gas flow path and configured to recover waste heat as saturated steam from exhaust gas;
• a steam accumulator configured to store steam formed by confluence of saturated steam parts, each generated by the waste heat boiler;
• a steam super heater configured to turn steam, which has been stored in the steam accumulator, into superheated steam by heating;
• a second exhaust gas flow path configured to lead exhaust gas, which has been treated with waste heat recovery in the waste heat boiler, to the steam super heater to use the exhaust gas for superheating saturated steam;
• and
• an operation section configured to operate the steel making electric arc furnaces to sequentially perform respective running operations by staggering the running operations with a predetermined deviation time,
• wherein the operation section sets the deviation time to minimize changes over time in the number of running furnaces of the steel making electric arc furnaces.