Sustainable process for the co-generation of pig iron and electric energy using wood as fuel

Abstract

An integrated and sustainable process is presented for the co-generation of pig iron and electric energy in a blast furnace installation in which dried wood replaces charcoal as the fuel, as the reducing and as the carburizing agent. Furthermore, this application incorporates the process—until now independent—of transforming wood into coal, inside the blast furnace.

Description

[0001]This application claims priority from U.S. Provisional Patent Application No. 61 / 566,874, filed in the United States Patent and Trademark Office on Dec. 5, 2011, the entire disclosure of which is incorporated herein by reference.BACKGROUND OF THE INVENTION[0002]Pig iron is an alloy of Iron and Carbon that is used as raw material for the production of steel. Selected species of wood are transformed into pieces of uniform and predetermined size such as chips (but not only this shape) that are dried to less than 10% Moisture Content and classified by size in a wood drying and classifying line so that only dry coarse particles are charged into the blast furnace. The large amount of water evaporated in the wood drying process may be recycled to reduce the amount of fresh water used in the process. The dry wood is heated inside the furnace with hot spent gas in order to initiate the exothermic carbonization process. The greater weight of wood in the charge, that is required to compe...

AI Technical Summary

Benefits of technology

[0073]We aim for a continuous carbonization (pyrolisis) process inside the Blast Furnace at a constant and ideal temperature that will produce charcoal in tens of minutes, rather than days, using spent gases from the combustion chamber. The process optimizes charcoal production efficiency, materials yield and charcoal quality, with minimum contamination. The charcoal produced is of homogeneous size and quality and will perform in an optimum way as a fuel as well as a high quality reducing and carburizing agent. The process may be carried out at a relatively high temperature (from 150° C. to 700° C. approximately). This higher temperature is supplied by the “hot gas loop” indicated in the flow sheet and accelerates the reduction reactions taking place inside the upper part of the furnace thus compensating for the temporary reduction of working volume caused by the heavier wood charge. The operator can now decide the optimum level of Fixed Carbon content based on the cost of energy, wood and pig iron instead of always aiming at the highest level of Fixed Carbon content of the charcoal. In effect, the operator can adjust the particle size, the ca...

Problems solved by technology

This energy, as well as many volatiles and fine charcoal particles that are pollutants, are normally vented and thus lost into the atmosphere.

Comment—though this patent mentions the use of a biomass material in contact with the iron ore, it does not establish such biomass material as being the only energy source, the only reduction source, and the only carburizing agent.

Furthermore, it does not consider substantial energy co-production, and it considers plastic resinous materials as one of the reactants, which we don't.

Furthermore, it does not consider a surplus energy production of a previous drying of the wood.

Furthermore, it does not consider cogeneration.

The second process is the Electric Arc Furnace (EAF) that produces steel in one step by melting recycled steel scrap and consumes great amounts of energy per ton of steel produced.

Although steel is considered an essential product for humanity, its production causes a series of environmental problems such as carbon dioxide emissions as well as ground, water and atmospheric pollution.

High energy consumption and a need to improve material efficiency are also important issues that confront the steel industry.

Continuous efforts are spent in attempting to solve these major problems around the world but an effective and efficient solution has not been found.

The charcoal production process generates CO and CO2 gas that, together with the fine particles that are lost to the ground and to the atmosphere produce air and water pollution.

Charcoal storage ...

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