Process Simulation and Economic Feasibility Analysis for a Hydrogen‐Based Novel Suspension Ironmaking Technology

Abstract

A novel gas‐solid suspension ironmaking process is under development at the University of Utah, which would greatly reduce energy consumption and carbon dioxide emission compared with current blast furnace technology. The proposed process is based on the flash reduction of iron ore concentrate using a gaseous reagent, such as hydrogen, syngas, natural gas or a combination of thereof. A process flow sheet of the proposed ironmaking process using purchased hydrogen was constructed and then simulations were performed at several potential operating conditions. Ironmaking was simulated using two different process configurations. The simulation results show that the required fresh hydrogen would increase with higher excess driving force and operating temperature, but not greatly when hydrogen is preheated. Compared with the average blast furnace process, the proposed process would reduce energy consumption by 57 ‐ 60%, using the higher heating value of hydrogen (71 – 73%, if the lower heating value is used), when hydrogen and coal are considered as the starting materials in the respective processes. The economic feasibility analysis using net present value (NPV) indicates that the proposed process could be economically feasible at elevated hot metal prices and/or if reduction in carbon dioxide emissions has a significant value in a cap and trade scenario.

Methods for Calculating Energy Requirements for Processes in Which a Reactant Is Also a Fuel: Need for Standardization

“…As part of this development work, Pinegar et al 5 prepared a material and energy flow diagram for a commercial-scale reformerless flash ironmaking process producing 1 million tonnes of iron per year and operating with natural gas using the commercially available software METSIM.…”

“…8), the energy requirement for the reduction process is the difference between the heats of Eqs. 6 and 8, which is equivalent to the heat of the following combustion reaction: [4][5][6] have used this approach.…”

“…The annual production rates in all the cases are 1 million tonnes of iron from a single unit of the ironmaking reactor. The energy balance for the flash ironmaking process is based on the flow sheet presented by Pinegar et al 5 Higher heating values (HHVs) of natural gas and hydrogen were used to be conservative in calculating the energy requirements, respectively, of reformerless flash ironmaking and hydrogen-based flash ironmaking. Table I.…”

“…Energy input items for a commercial-scale flash ironmaking process using natural gas or hydrogen compared with those for an average blast furnace process (production rate = 1 million tonnes of iron per year at 1773 K (300 days of operation in 1 year).) Adapted from Pinegar et al 4 The energy requirement for hydrogen production was not included for this calculation. It is anticipated that the energy required for hydrogen production will strongly depend on the production process such as steam-methane reforming, coal gasification, or water splitting.…”

“…The results of applying Approach 2 were adapted from Pinegar et al 4,5 and those of applying Approach 1 were calculated by modifying the ''Fuel combustion'' term in the input category and the ''Reduction'' term in the output category, which are the only numbers that are different between Approaches 1 and 2. Table II.…”