Christer Ryman

Bio: Christer Ryman is an academic researcher from Luleå University of Technology. The author has contributed to research in topics: Steelmaking & Energy engineering. The author has an hindex of 6, co-authored 12 publications receiving 194 citations. Previous affiliations of Christer Ryman include ArcelorMittal.

A model on CO2 emission reduction in integrated steelmaking by optimization methods

Abstract: The iron and steel industry is a large energy user in the manufacturing sector. Carbon dioxide from the steel industry accounts for about 5-7% of the total anthropogenic CO2 emission. Concerns abou ...

Reduction of CO2 Emissions from Integrated Steelmaking by Optimised Scrap Strategies: Application of Process Integration Models on the BF–BOF System

Abstract: In integrated steelmaking there are a number of means to reduce CO 2 emissions. One approach is to increase the metallic Fe input to the production system. A common belief is that scrap works as a CO 2 diluent when introduced in iron ore based steelmaking. It is not necessarily so. Scrap is a key supplementary charge material in oxygen steelmaking converters, but scrap can also be utilised in ironmaking where it will decrease the use of'reducing agents and with that also the specific CO 2 emissions. By the use of a process integration model which basically includes the primary processes of cokemaking, sintering, ironmaking and oxygen steelmaking the overall influence of scrap input on CO 2 emissions is demonstrated and commented. The influence of hot metal silicon content is elucidated by calculations with different material and process constraints. The results show that at moderate scrap rates, the reduction of CO 2 emissions is favoured by increased scrap additions to the oxygen converter. When the scrap additions to the converter balances the actual heat capacity of the bath, other means to achieve an increased scrap melting capacity can be taken into account. This include combinations of scrap addition to the blast furnace, increased silicon content in tapped hot metal, and/or addition of Ferro-silicon combined with further scrap additions to the oxygen converter. Different strategies for CO 2 emission reduction have to be suggested depending on if the objective is to minimise the site (direct) emissions or the global (indirect+direct) emissions.

Adaptation of Process Integration Models for Minimisation of Energy Use, Co2-emissions and Raw Material Costs for Integrated Steelmaking

Abstract: The structure of the energy and mass flows in steelmaking is rather complex with a lot of connections between the unit processes. A further developed optimisation model for integrated steelmaking based on mixed integer linear programming (MILP) is described. The system includes today’s dominating steel production route, basic oxygen steelmaking, based on iron ore, steel scrap, and carbonaceous reducing agents. Multi or single objective minimisation problems in steelmaking are represented by energy use, CO2 emissions and raw material cost to produce steel slabs. Finally the paper briefly discusses the effects of process and product related constraints on the modelling results.

Cooperation and competition among structural materials

Abstract: Materials have been invented by mankind in the course of prehistory and history and have evolved during this long period of time to fit the parallel changes in technological epistemes. Materials, therefore, have been a cumulative technological commodity, because of the continuity that this mechanism of change has ensured Structural materials, of which all anthropogenic artefacts are made and with which they are made (machines, process tools, etc.), have been more especially enduring and have carved themselves specific roles in our world that survive across major paradigm shifts and Kondratief cycles. Materials are analyzed here in terms of their physico-chemical nature (or physio-chemical in the case of natural, renewable materials) and of their footprints on energy consumption and greenhouse gas emissions, two of the major lenses through which the sustainability of our economic world is presently observed. The picture that comes out of this examination is that of complementarity and cooperation between materials, with competition acting as a sting to avoid a slack in technology but no pushing any of them out of their market, at least globally. This cohabitation, akin to a natural selection mechanism in a global ecosystem, may be the real driver of dematerialization, a trend which population growth and urbanization forces on mankind.

A state-of-the-art review of biomass torrefaction, densification and applications

Abstract: Torrefaction is a mild pyrolysis, which has been explored for the pretreatment of biomass to increase the heating value and hydrophobicity. Due to its potential applications for making torrefied pellets, which can be used as a high quality feedstock in gasification for high quality syngas production and as a substitute for coal in thermal power plants and metallurgical processes, torrefaction and densification have attracted great interest in recent years from both academia and bioenergy industry. This paper provides a comprehensive review of research progresses in this area, drawing on major contributions from two major research groups of the authors on torrefaction and densification at Canada and Taiwan as well as literatures. It is revealed that torrefaction of various biomass species and their major components, lignin, cellulose and hemicelluloses have been extensively studied in thermogravimetric apparatus (TGA) under both inert (N 2 ) and oxidative (O 2 , H 2 O) environments to elucidate the weight loss as a function of temperature, particle size and time. It was found that the higher heating value and saturated water uptake of torrefied biomass were a strong function of weight loss, which represents the degree of torrefaction. When torrefied sawdust is compressed into torrefied pellets, more mechanical energy is consumed and higher die temperature is required to make torrefied pellets of similar density and hardness as regular pellets. Simple economics analyses based on laboratory scale experimental data showed that because of the potential savings from pellets transport, handling and storage logistics, the overall cost for torrefied pellets can be lower than regular pellets in European market for both European and Canadian pellets. The gasification could be improved in terms of both energy efficiency and syngas quality because of the removal of oxygenated volatile compounds from torrefied biomass.