Carl-Erik Grip

Black liquor fractionation for biofuels production - a techno-economic assessment.

The hemicelluloses fraction of black liquor is an underutilized resource in many chemical pulp mills. It is possible to extract and separate the lignin and hemicelluloses from the black liquor and use the hemicelluloses for biochemical conversion into biofuels and chemicals. Precipitation of the lignin from the black liquor would consequently decrease the thermal load on the recovery boiler, which is often referred to as a bottleneck for increased pulp production. The objective of this work is to techno-economically evaluate the production of sodium-free lignin as a solid fuel and butanol to be used as fossil gasoline replacement by fractionating black liquor. The hydrolysis and fermentation processes are modeled in Aspen Plus to analyze energy and material balances as well as to evaluate the plant economics. A mathematical model of an existing pulp and paper mill is used to analyze the effects on the energy performance of the mill subprocesses.

Comprehensive Study Regarding Greenhouse Gas Emission from Iron Ore Based Production at the Integrated Steel Plant SSAB Tunnplåt AB

During the years 2001–2002, a comprehensive study regarding CO2 emissions related to the steel production for the integrated steel making production route, was carried out. The study was financed by SSAB and carried out by a research group with members from SSAB, MEFOS and LTU. The aim was to study the emissions from the existing system and how these could be influenced by process changes and by process modifications. The calculations were made using a global spreadsheet model for calculating the CO2 emissions, developed from an existing Energy and Process Integration model of the same system. The calculated cases included the existing BF/BOF route as well as integration of other processes, e.g., an electric arc furnace, DR processes, COREX and a new future smelting reduction process concept (Sidcomet). All new existing alternative ore based process technologies would increase the specific CO2 emission from the system. A technology transfer to scrap based metallurgy would significantly decrease the emission level, but is not feasible for SSAB, due to the future product mix and the structure of scrap availability. In a 5–20 year perspective, the existing steel making process route with the use of magnetite ore for pellet production has the lowest specific CO2 emission. In a long-term perspective, 20–50 years, alternative process routes, e.g., based on H2 and DRI, could be of interest. Studies on such changes are, however, big projects and should be carried out as joint European and/or international efforts.

Possibility to combine exergy with other process integration methods for a steelmaking case

The energy system of Lulea consists of the steel plant, a local CHP using process gases from the plant and the district heating system. Process integration work to improve the efficiency of the sys ...

Process simulation and energy optimization for the pulp and paper mill

A process integration model is developed based on mixed integer linear programming. The analysis is carried out using the reMIND software in combination with the commercial optimization software CP ...

Steel industry environmental objectives: stakeholder preference assessment using conjoint analysis

Abstract The Swedish steel industry has combined traditional methods such as life cycle analysis with less traditional methods such as preference analysis in order to move towards a closed steel eco cycle. The paper describes the use of conjoint analysis to study preferences of six different stakeholder groups regarding four environmental objectives (reduction in carbon dioxide emissions, reduced use of non-renewable resources, reduced use of non-renewable energy and weight reduction in products) and to identify gaps in preferences between the stakeholder groups. Our results suggested that there was a difference in preference between the stakeholder groups: respondents that were closer to the steel industry favoured all four environmental objectives, while members of public and political decision makers preferred a reduction in carbon dioxide emissions. One of the conclusions of our study is that there is a need of improved information to clients and public on the environmental benefits of product weight reduction.