Impact of Co-Injecting Hydrogen and Australian PCI Coals on Overall Blast Furnace Performance Using a Heat and Mass Balance Model

This project aimed to evaluate the impact of the co-injection of Australian PCI coals and hydrogen on overall blast furnace (BF) performance using a Heat and Mass Balance (HMB) model which is available directly from UNSW via the email below.  The model will be used to assess several key BF parameters including Raceway Adiabatic Flame Temperature (RAFT), Top Gas Temperature (TGT), fuel rate, production rate and CO₂ emissions, for a range of Australian PCI coals, when injected into the tuyeres or co-injected with hydrogen, and to identify the requirements for optimum Australian PCI coal products with respect to overall BF performance when different co-injection scenarios are employed.

Hydrogen is a climate-friendly fuel and is regarded as a promising potential fuel to reduce coal use in future ironmaking. The co-injection of coal and hydrogen is regarded as the most feasible way to reduce carbon use in the BF as it requires very low modification of the BF operation and facilities. It is essential to understand the impact of the co-injection on BF operation.  HMB is widely used by BF ironmakers (our end-users), and is well received as a reliable and cost-effective tool for BF operations planning and analysis. The understandings are significant for Australian coal industry to better prepare for future H₂-involved ironmaking and the risk analysis, before the competitors. The suitable PCI coals are identified for the co-injection technology, and the optimal operations are identified for the specific Australian PCI coals for the technology development of co-injecting coal and hydrogen.

A HMB model has been first developed for estimating the impact of the co-injection of coal and hydrogen on overall BF performance, including RAFT, TGT, fuel rate, coke rate, production rate, bosh gas volume, pressure drop, degree of utilisation of CO and H₂, calorific value of top gas, CO₂ emission. The HMB calculation is performed by applying the mass balance equations and the energy balance equation to each chemical element and species in an ironmaking BF. This provides the mathematical solver with a set of equations.  This system has a unique solution when the number of unknown variables is equal to the number of independent equations, where some variables are fixed to solve the system. For flexibility, different sets of variables can be chosen to be constraints in different scenarios.  Secondly, the HMB model has been used to conduct massive calculations for a series of scenarios of co-injection of different Australian PCI coals and hydrogen. Several key concerns or questions have been explored based on the massive HMB calculations, such as the dynamic interaction between the RAFT and TGT and possible countermeasures to control them; and the maximum hydrogen injection limit under certain constraints (e.g., RAFT reduction and PCI replacement). Finally, a set of operational design diagrams have been developed based on the HMB results under a range of scenarios. A strong research team was assembled for this project.

In this project, a versatile general-purpose HMB BF model is refined and customised for the co-injection of ACARP PCI coals and H2 in an Australian BF. The model outputs include operating parameters for the furnace, e.g., the operating window, the quantities and compositions of both the top charged materials (ores, coke, fluxes) and the blast conditions (coal types, various gases; including sustainable injectants).

The key results of the project are summarised in the final report.

THE MODEL IS AVAILABLE FROM THE RESEARCHER.