Carl-Johan Fogelholm

Reduction of CO2 Emissions from steel plants by using steelmaking slags for production of marketable calcium carbonate

By carbon dioxide mineralization, CO2 can be stored safely and leakage-free for very long times. Owing to their high calcium content, steelmaking slags are suitable for mineral carbonation. In a country like Finland, where no suitable geological formations for CO2 storage seem to exist, steelmaking slag carbonation offers an important CO2 emissions reduction option for steel plants. If calcium could be extracted selectively from the slags prior to carbonation, a pure, and possibly marketable, calcium carbonate may be produced. This could replace some of the natural and synthetic CaCO3 used in industry, combining savings in natural resources with CO2 emissions reduction. Development work on the production of pure calcium carbonate from steelmaking slags by carbonation is presented in this study. Selective extraction of calcium from steelmaking slags was investigated using various solvents. Precipitation of CaCO3 from dissolved calcium at atmospheric pressure was also investigated. Amongst the various tested solvents ammonium salt solutions (NH4Cl, CH3COONH4, NH4NO3) were found to be the most promising for selectively extracting calcium from steel converter slag. These solvents dissolved calcium efficiently also from desulphurization slag, while extraction of calcium from two other types of slag was poor. CaCO3 was successfully precipitated from the solution containing ammonium salt and dissolved steel converter slag.

An interactive multi-objective approach to heat exchanger network synthesis

In this work we present a multi-objective approach to heat exchanger network synthesis. The approach solves a modified version of the Synheat model using an interactive multi-objective optimisation method, NIMBUS, which is implemented in GAMS. The results obtained demonstrate the potential of interactive multi-objective optimisation.

A bilevel optimization method for simultaneous synthesis of medium-scale heat exchanger networks based on grouping of process streams

Abstract In this work we present a bilevel optimization method for simultaneous synthesis of heat exchanger networks (HENS). The results show that compared to a similar method using the same superstructure the presented method can provide comparative solutions to HENS problems with reduced calculation effort especially for larger problems. Hence the value of this work is a good way of simplifying a HENS problem so that HENS problems can be solved efficiently with good results. The presented method combines four submodels into an overall method by using grouping of streams, aggregate streams and bilevel optimization. The idea of the method is to decompose the set of binary variables i.e. the variables that define the existence of heat exchanger matches, into two separate problems. Three different HENS examples from the literature are solved.

Prediction of gas composition of Jatropha curcas Linn oil cake in entrained flow reactors using ASPEN PLUS simulation software.

A prediction for product gases of Jatropha curcas Linn (JCL) oil cake gasified in the entrained flow reactor is studied in this paper. ASPEN PLUS commercial software is used to carry out the simulation using Gibbs free energy minimisation with equilibrium phase. A series of simulations and analyses have been carried out to investigate the composition of product gases in JCL oil cake with reactor temperature ranging from 1000 to 1400°C. In the first prediction step, the gas composition of sawdust and rice husk are validated. After this, the simulation model is used to predict JCL oil cake gas composition. Mean error analysis is carried out to identify the maximum and minimum error of the simulation. The results show that with increasing reactor temperature, the amount of carbon monoxide (CO) and hydrogen (H2) increases while the amount of carbon dioxide (CO2) and methane (CH4) decreases. The results of the gas composition of JCL oil cake show that the CO content at a temperature of 1000°C ranges from 41.35% to 53.36%. Composition of other gases such as hydrogen (H2), carbon dioxide (CO2), methane (CH4) is 24.65–32.7%, 4.4–22.99% and 0.94%–19.62%, respectively.

Modeling the dissolution of carbonate minerals utilized in Flue Gas Desulfurization scrubbers.A stepwise titration technique applied to low Grashof-Reynolds ratio

Every year a significant amount of Sulfur Dioxide (SO2) is discarded in the atmosphere. SO2 can cause indirect ozone depletion, it leads to the formation of acidic rains and a large number of diseases are provoked by contact with sulfur dioxide. Limestone (CaCO3) is widely utilized in Flue Gas Desulfurization (FGD) processes because of its ability to capture the sulfur and precipitate as solid gypsum. The correct evaluation of limestone reactivity is a key aspect for FGD wet scrubbing process design and plant operation. In the present study results from tests to a particular group of samples classified as Sedimentary Limestone and Sedimentary Dolomite are reported.