Plant and method for the thermal treatment of solids
A method and its related plant for the thermal treatment of iron containing oxide, in which fine-grained solids are heated in a preheating calcining stage and exposed to a reduction gas in a subsequent reduction stage. Off-gas from the reduction stage is guided through a separation device wherein water originating from the reduction stage is separated. The water separated in the separation device is recycled into a water treatment section, from which the recycled water is supplied to a water electrolysis plant and/or a steam reforming plant producing hydrogen, and the produced hydrogen is supplied to the reduction stage as reductant and/or to the preheating calcining stage as fuel and/or to the gas heater as fuel and/or from which the recycled water is supplied to the separation device.
1. A method for the thermal treatment of iron containing oxide, in which fine-grained solids are heated in a preheating calcining stage and are exposed to a reduction gas in a subsequent reduction stage, wherein off-gas from the reduction stage is guided through a separation device, separating water originating from the reduction stage, wherein off-gas from the preheating calcining stage is guided through a venturi scrubber and a packed bed section downstream of the venturi scrubber to condense water vapor, wherein water separated in the separation device is recycled into a water treatment section, from which the recycled water is supplied to at least one of a water electrolysis plant or a steam reforming plant producing hydrogen, and that the produced hydrogen is supplied to at least one of the reduction stage as reductant, to the preheating calcining stage as fuel, to a gas heater as fuel, or from which the recycled water is supplied to the separation device as process water, wherein the process water exchanges heat with the off-gas, is cooled in the water treatment section and is recirculated to the separation device,
wherein oxygen generated in the at least one of the water electrolysis plant or the steam reforming plant is supplied to at least one of the preheating calcining stage or the gas heater for the combustion of fuel.
2. The method according to claim 1 , wherein at least one of the preheating calcining stage or the reduction stage comprises a fluidized bed reactor.
3. The method according to claim 1 , wherein at least one of the preheating calcining stage or the reduction stage comprises a circulating fluidized bed reactor.
4. The method according to claim 1 , wherein at least one of the preheating stage or the reduction stage is heated with at least one gas heater, and that the off-gas from the at least one gas heater is guided through a separation device to condense water vapor.
5. The method according to claim 1 , wherein the downstream of the reduction stage the reduced solids are cooled in a quench cool, and that the off-gas from the quench cool is guided through a separation device to condense water vapor.
6. The method according to claim, 5 wherein the quench cool is a vibratory cooling conveyor.
7. The method according to claim 1 , wherein at least one of the hydrogen content in the reduction gas is at least 85 v/v.-%, and/or the hydrogen content in a fuel gas used in the preheating stage is at least 20 v/v.-%, or the hydrogen content in a fuel gas used in at least one gas heater is at least 20 v/v.-%.
8. The method according to claim 1 , wherein water treatment section includes removal of solids, removal of incondensable gases and indirect cooling.
9. A plant for the thermal treatment of iron containing oxide comprising a preheating calcining stage, for heating up fine-grained solids and a reduction stage, for reducing the heated solids by exposure to a reduction gas comprising hydrogen, wherein an off-gas outlet of the reduction stage is connected to a separation device to condense water vapor from the off-gas of the reduction stage, wherein an off-gas outlet of the preheating calcining stage is connected to a venturi scrubber and a packed bed section arranged downstream of the venturi scrubber to condense water vapor wherein a water outlet of at least one separation device is connected to a water treatment section for recycling water, that the water treatment section is coupled to at least one of a water electrolysis plant a steam reforming plant producing hydrogen as a reductant for the reduction stage, as a fuel for the preheating calcining stage, to a gas heater as fuel or that the water treatment section is coupled to at least one separation device to provide process water, which exchanges heat with the off-gas, is cooled in the water treatment section and is recirculated to the separation device,
wherein oxygen generated in the at least one of the water electrolysis plant or the steam reforming plant is supplied to at least one of the preheating calcining stage or the gas heater for the combustion of fuel.
10. The plant according to claim 9 , wherein the water treatment section comprises at least one of a thickener with a filter press for the filtration of underflow slurry or a covered water surface of the thickener.
11. The plant according to claim 9 , wherein the water treatment section comprises a warm water tank for chemical treatment.
12. The plant according to claim 9 , wherein water treatment section comprises at least one of an air fan cooler or a chiller for cooling the water.
13. The plant according to claim 9 , wherein the water treatment section comprises at least one of a water filter or an ion exchange device.