Characterization of Process Conditions in Industrial Stainless Steelmaking Electric Arc Furnace Using Optical Emission Spectrum Measurements

Emission spectroscopy is a potential method for gaining information on electric arc furnace (EAF) process conditions. Previous studies published in literature on industrial EAF emission spectra have focused on a smaller scales and DC arc furnaces. In this study emission spectrum measurements were conducted for 140t AC stainless steelmaking EAF at Outokumpu Stainless Oy, Tornio Works, Finland. Four basic types of emission spectra were obtained during the EAF process cycle. The first one is obscured by scrap steel, the second is dominated by thermal radiation of the slag, the third is dominated by alkali peaks and sodium D-lines and the fourth is characterized by multiple atomic emission peaks. The atomic emission peaks were identified by comparing them to the NIST database for atomic emission lines and previous laboratory measurements on EAF slag emission spectra. The comparison shows that the optic emission of an arc is dominated by slag components. Plasma conditions were analyzed by deriving plasma temperature from optical emissions of Ca I lines. The analysis suggests that accurate information on plasma conditions can be gained from outer plasma having a plasma temperature below 7000 K (6727 °C).     

Moth‐eye antireflection coating fabricated by nanoimprint lithography on 1 eV dilute nitride solar cell

We report on the performance of biomimicked antireflection coating applied to dilute nitride solar cell. The coating consists of nanostructures replicating the moth‐eye geometry and has been fabricated by nanoimprint lithography directly within the window layer covering the dilute nitride absorbing junction. The mean reflectivity within the spectral range of 320–1800 nm remains under 5% for incident angles up to 45°. The effect of the coating on the cell performance was assessed by measuring the current–voltage characteristics under simulated solar illumination. A clear performance increase was identified when comparing a solar cell with the moth‐eye coating with a solar cell having a standard SiN_x/SiO₂ coating. Copyright © 2012 John Wiley & Sons, Ltd.     

Performance analysis of power generating sludge combustion plant and comparison against other sludge treatment technologies

Expectations on wastewater sludge treatment and recovery of its energy and material contents are increasing because of the tightening legislation and the obligation to reduce environmental impacts of sludge disposal. The objective of this study was to analyze the performance of a heat and power generating sludge combustion plant from technical and economical viewpoints and to compare the studied concept to optional sludge treatment technologies. The plant performance was modeled for sewage sludge produced by approximately 200,000 inhabitants. Two plant sizes below 1000 kWe range were investigated, the smaller plant using sludge as the only fuel and the larger plant with wood chips as the additional fuel. The plants were compared with heat-only plants of similar size. The payback periods for heat-only plants are typically shorter than with the cogenerating plants because the changes in plant investment affect stronger the economy than do the revenues from selling electricity. The gate fee of sludge treatment has the strongest effect on the payback period. The selection of the plant concept (cogeneration, heat only or pure electricity generation) is, however, affected more by the local demand of heat and electricity than pure economy. The selection of the optimal technology for sludge treatment is a complicated task. The studied concept can be the optimal choice, for example, if there is no cement kiln or co-combustion possibility near the source of sludge, if there is no land enhancement demand for the digested sludge, or if the energy surplus from combustion compared to anaerobic digestion is considered more valuable than nutrient recovery possibility from digestion. If the new technology concept is found competitive, it still has to meet the challenge of acceptability from the business, social and cultural points of view.     

Influence of wind power,plug-in electric vehicles,and heat storages on power system investments

Due to rising fuel costs, the substantial price for CO₂ emissions and decreasing wind power costs, wind power might become the least expensive source of power for an increasing number of power systems. This poses the questions of how wind power might change optimal investments in other forms of power production and what kind of means could be used to increase power system flexibility in order to incorporate the variable power production from wind power in a cost-effective manner.     

Kinetics of glucose decomposition in formic acid

Cellulose is abundantly available in the form of forestry and agricultural lignocellulosic residues. These residues offer the most potential source for the production of cellulosic glucose, which is a prerequisite for the sustainable production of glucose-based fuels and chemicals. Acid catalysis is one path to lignocellulosic glucose and further to its dehydration end products. Furthermore, many studied lignocellulose pretreatment methods for enzymatic hydrolysis are carried out in acidic conditions, in which the unwanted release of hemicellulose-based glucose and its further reactions to harmful end products are possible. Thus, in order to maximize glucose production from non-food cellulosic raw materials, data on the kinetics of cellulose decomposition and formation rates of end products are required. Glucose decomposition is a complex reaction system that has often been modelled with empirical, simplified models. In this study, a kinetic model was developed for glucose decomposition in formic acid solution. The experimentation was carried out in batch reactors at 180-220 °C in 5-20% (w/w) formic acid. The model developed relies on a mechanistic step through an unknown substance and gives excellent correspondence to the experimental data despite the pseudo-elementary nature of the model structure.     

Electrical capacitance tomography as a monitoring tool for high-shear mixing and granulation

Electrical capacitance tomography (ECT) was utilized for monitoring of high-shear mixing and high-shear granulation processes. A finite element method (FEM)-based reconstruction algorithm was utilized to take into account the specific geometrical characteristics of the experimental set-up. Two-dimensional ECT tomograms, mixing index curves and permittivity fractions were computed based on the measurements, and their suitability in the analysis of the processes was assessed. It was found that the different mixing processes and the different granulation processes could be analyzed based on these quantities.     

Measurement of Particulate Carbon in Atmospheric Aerosol in Helsinki

By means of a simple optical apparatus the levels and variations of concentrations of elemental carbon in particles were measured. Additionally, relations between variations of elemental carbon, lead, sulfate, total suspended particle, and nitrate concentrations were studied. Calibration was performed on real samples analyzed by a wet chemical method.     

A qualitative H NMR study of CHCl3 adsorption on conjugated acid–base pairs in cation exchanged Y-zeolites

Solution state ¹H NMR is employed to study the mode and strength of chloroform adsorption on conjugated acid–base pairs of cation-exchanged Y-zeolites. ¹H NMR results indicate that two different surface bonding orientations may exist. An acidic hydrogen site of zeolite favours orientation where the chloroform hydrogen points towards the zeolite cage centre. An exchanged electropositive cation increases the basicity of framework oxygens of zeolite and directs the chloroform to adsorb on framework oxygens with a hydrogen bond. In this adsorption site the chemical shift of the chloroform hydrogen has a linear dependence on the electronegativity of the cation.     

制浆造纸行业节能型真空系统——Ecopump节能透平机

通过与制浆造纸行业现有的液环泵和单/多级透平风机两种真空系统进行比较,介绍了芬兰Ecopump节能透平机真空系统技术及其优势所在。Ecopump节能透平机可为纸机真空系统节能30%~70%,同时具有投资回报快、安装维护快且简单等特点。     

Synergism of enzymes in chemical pulp bleaching from an industrial point of view: A critical review

Enzymes are biological catalysts and are very specific, catalyzing either a single chemical reaction or a limited number of closely related reactions. For example, xylanases are enzymes that catalyze the cleavage of polymeric xylan and thereby break down this hemicellulose. The first xylanase enzyme preparations used in the bleaching process of chemical pulp also contained cellulase, which catalyzes the hydrolysis of cellulose. This obviously had an adverse effect on pulp yield and quality. Unfortunately, this setback gave enzyme-assisted pulp bleaching a negative reputation. At a later stage, enzyme producers managed to engineer enzyme production strains that generated cellulase-free xylanase preparations. However, due to the initial negative experiences with the earlier enzyme mixtures, only a limited number of companies in the pulp industry have seriously considered using these so-called second-generation enzymes in their bleach plants. It is apparent that these improved enzyme preparations would bring about significant benefits in terms of chemical cost savings and effluent quality. In addition to xylanase-aided bleaching, it is possible to improve the effectivity further by adding other enzymes, such as lipase and esterase, to create an enzyme cocktail. This may be particularly beneficial in the bleaching of hardwood pulp, such as white birch, which often encounters complex and troublesome problems with wood extractives. By adding different types of enzymes at more than one position in the fiberline, even further improvements are possible. The main objective of this review is to discuss the advantages of incorporating modern enzyme preparations in the bleaching of chemical pulp.