Abstract
The present paper focuses on the production of a below zero emission reducing gas for use in raw iron production. The biomass-based concept of sorption-enhanced reforming combined with oxyfuel combustion constitutes an additional opportunity for selective separation of CO2. First experimental results from the test plant at TU Wien (100 kW) have been implemented. Based on these results, it could be demonstrated that the biomass-based product gas fulfills all requirements for the use in direct reduction plants and a concept for the commercial-scale use was developed. Additionally, the profitability of the below zero emission reducing gas concept within a techno-economic assessment is investigated. The results of the techno-economic assessment show that the production of biomass-based reducing gas can compete with the conventional natural gas route, if the required oxygen is delivered by an existing air separation unit and the utilization of the separated CO2 is possible. The production costs of the biomass-based reducing gas are in the range of natural gas-based reducing gas and twice as high as the production of fossil coke in a coke oven plant. The CO2 footprint of a direct reduction plant fed with biomass-based reducing gas is more than 80% lower compared with the conventional blast furnace route and could be even more if carbon capture and utilization is applied. Therefore, the biomass-based production of reducing gas could definitely make a reasonable contribution to a reduction of fossil CO2 emissions within the iron and steel sector in Austria.
Highlights
Today the iron and steel industry in member states of the European Union (EU-28) is responsible for 200 million tons of carbon dioxide [1] which amounts to a share of 5% of the total carbon dioxide equivalent (CO2e) [2] emissions [3]
It can be seen that 50,400 kg/h of wood chips and 11,020 Nm3/h of pure oxygen are required for the generation of 28,800 Nm3/h product gas
The concept is based on the assumption that the reducing gas is compressed and preheated before it is fed to the direct reduction plant
Summary
Today the iron and steel industry in EU-28 is responsible for 200 million tons of carbon dioxide [1] which amounts to a share of 5% of the total carbon dioxide equivalent (CO2e) [2] emissions [3]. With respect to the estimates regarding biomass potential in the decades [20, 21], in Austria beside the rise of the share of steel production through scrap-based electric arc furnaces, another possible synergetic transition option seems to be the replacement of the integrated blast furnace route with the direct reduction of iron ore based on biomass-based reducing gas. Following question has not been answered sufficiently: How can the production of biomass-based reducing gas via dual fluidized bed steam gasification enable a reasonable contribution to a reduction of fossil CO2 emissions within the iron and steel sector?. The following paper describes the results of the investigated process enabling the production of a below zero emission reducing gas by applying the biomass-based dual fluidized bed steam gasification technology in combination with carbon capture and utilization. & Experimental and simulation results achieved & The results of a techno-economic assessment
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