Energy efficiency improvement of dryer section heat recovery systems in paper machines – A case study

Modern paper machines are equipped with heat recovery systems that transfer heat from the humid exhaust air of the paper machine’s dryer section to different process streams. As a result of process changes, the heat recovery systems may operate in conditions far from the original design point, creating a significant potential for energy efficiency improvement. In this paper we demonstrate this potential with a case study of three operating paper machines. Both operational and structural improvement opportunities are examined. Since the existing retrofit methodologies for heat exchanger networks can not be applied to cases with condensing air, we use thermodynamic simulation models presented earlier to assess the effects of possible changes on the existing heat recovery systems. In order to reduce the required processing time of the simulation models, only a limited number of pre-screened retrofit designs are considered. The pre-screening is carried out on the basis of guidelines presented earlier. The analysis in the case mill revealed savings of 110 GWh/a in process heat with profitable investments. According to the follow-up study, the investments carried out have resulted in 12% lower fuel use and 24% lower CO₂ emissions. The results imply that all operating paper machines should be similarly examined.     

Experimental Novel Silane System in Adhesion Promotion Between Dental Resin and Pretreated Titanium

Five silane blends were evaluated as experimental adhesion-promoter primers. First, five organosilane monomers (silicon esters), 3-acryloxypropyltrimethoxysilane, 3-methacryloxypropyltrimethoxysilane, 3-glycidoxypropyltrimethoxysilane, tetrakis-(2-ethyloxyethoxy)silane and bis-[3-(triethoxysilyl)propyl]tetrasulfide, were diluted to 1% (v/v) and blended with a non-functional cross-linking silane, 1,2-bis-(triethoxysilyl)ethane (1%), in 95% ethanol. After activation, each blend was applied to silica-coated Ti coupons. A resin based on bis-phenol-A-diglycidyldimethacrylate was then bonded and photo-polymerized as stubs to the pretreated Ti coupons. Half of the specimens were stored in dry conditions and half were artificially aged by thermo-cycling. The primers containing 3-acryloxypropyltrimethoxysilane and 3-methacryloxypropyltrimethoxysilane produced significantly higher shear bond strength values than the control silane, a standard pre-activated product used in clinical dentistry.     

Optimisation model for integration of cooling and heating systems in large industrial plants

Large industrial plants have often hundreds of heating and cooling heat exchangers. A common situation is that cooling demands of the processes are satisfied without any deeper analysis of the overall impact of the cooling systems on the plant’s economy or the environment. If cooling water is available it is used as much as needed and then pumped back to the river, some degrees warmer.An optimisation model was developed for integration of cooling and heating systems to tackle the problem. An industrial cooling system is a complex energy system comprising different options of producing cooling, distribution pipelines for cold media and cooling storages. Integration of power generation and heating systems to the cooling systems was included in the model. An illustrative example is presented in the paper. 10 process streams with cooling demand and 10 streams with heating demand were chosen, situated at different locations at the plant site. The optimal matches between the streams were found together with the sizes of the heat exchangers and the demands of hot and cold utilities. The costs of pipelines and the pumping costs of the streams are included in the model. The model can be used in the design of greenfield and retrofit investments and in versatile what-if analyses of the plant design or operation.     

Commitment Nets in Software Process Improvement

Several studies have revealed the fact that nearly two-thirds of all software process improvement (SPI) efforts have failed or have at least fallen short of expectations. Literature and practice have shown that commitment to SPI at all organizational levels is essential for the success of any SPI endeavor. A research model for studying the existence, development and interplay of SPI-related commitment is introduced in this paper. This study suggests that software organizations operate through strategic, operational and personal commitment nets. These nets consist of actors, drivers, concerns, actions, commitment, and outcomes. The commitment nets model is applied in a study of four industrial SPI initiatives. The results from two of these cases are reported here. The results show that SPI is driven through the formation and reformation of commitment nets. The contents of strategic, operational and personal commitment nets are laid out and implications are discussed.     

Foreperiod and simple reaction time.

Reviews studies of simple visual and auditory reaction processes published since W. H. Teicher (1954), with emphasis on the preparatory phase of these processes, particularly the foreperiod (FP). The 1st section consists of the analysis of actual FP variables; duration, regularity, range, distribution, and preceding FPs. The 2nd section deals with factors affecting the relation between FP and reaction time (RT): (a) the modality, intensity, probability, and duration of the warning signal and reaction stimulus (RS) and (b) the speed–accuracy trade-off. It is suggested that the S's expectancy (momentary probability of the immediate delivery of the RS) is the most important determinant of the preparation to respond to the RS at any moment during a trial and, hence, of RT. Many factors exert their influence on preparation through their effect on expectancy. Other factors have a direct influence on preparation: short-term exhaustion and fatigue, immediate arousal evoked by intense auditory stimuli, the S's stimulus criterion, the speed–accuracy trade-off, and fluctuation in motor preparedness owing to inaccuracies in the control of motor preparation. (4? p ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Microchip atmospheric pressure chemical ionization source for mass spectrometry

A novel microchip heated nebulizer for atmospheric pressure chemical ionization mass spectrometry is presented. Anisotropic wet etching is used to fabricate the flow channels, inlet, and nozzle on a silicon wafer. An integrated heater of aluminum is sputtered on a glass wafer. The two wafers are jointed by anodic bonding, creating a two-dimensional version of an APCI source with a sample channel in the middle and gas channels symmetrically on both sides. The ionization is initiated with an external corona-discharge needle positioned 2 mm in front of the microchip heated nebulizer. The microchip APCI source provides flow rates down to 50 nL/min, stable long-term analysis with chip lifetime of weeks, good quantitative repeatability (RSD < 10%) and linearity (r(2) > 0.995) with linear dynamic rage of at least 4 orders of magnitude, and cost-efficient manufacturing. The limit of detection (LOD) for acridine measured with microchip APCI at flow rate of 6.2 muL/min was 5 nM, corresponding to a mass flow of 0.52 fmol/s. The LOD with commercial macro-APCI at a flow rate of 1 mL/min for acridine was the same, 5 nM, corresponding to a significantly worse mass flow sensitivity (83 fmol/s) than measured with microchip APCI. The advantages of microchip APCI makes it a very attractive new microfluidic detector.     

Computational support to record and re-experience visits

Information technology research has mainly focussed on supporting visitors with guides, whilst a lot of opportunities for the development of technology for collecting, manipulating and re-travelling through material from the visits remain unexplored. On the basis of observations from a specific setting, we have developed prototype technology to combine multimedia content with position information. In particular, we developed mobile support to record and organise multimedia using the walked path in order to preserve more of the experience of the visit. We created tools to edit and store multimedia paths. Additional components make it possible to configure a mixed-media environment to navigate a multimedia path, using such physical interfaces as gesturing, and link the recorded media to other artefacts. When discussing field observations of current practices and prototype trials, we investigate what kind of functionality is needed to support the whole activity of collecting, manipulating and playing multimedia content in combination with position information.     

A new table for work with a microscope, a solution to ergonomic problems

Microscope workers are exposed to continuous static muscular work and an increased risk of musculoskeletal disorders in the neck, shoulder and upper extremities. In a Finnish research centre, microscope workers reported pain in the shoulder, neck, lower back and upper back. As a consequence, a programme to solve the ergonomic problems of microscope work was initiated and led to the construction of a new table for microscopes. Ten experienced male microscope workers were chosen as subjects to carry out an experimental study in which the new table and an old one, an ordinary non-adjustable laboratory table, were compared in a standardized microscope task. The dependent variable was the electromyographic activity measured from muscles in the neck–shoulder region. The new table allowed the microscope to be used with the head in an upright position, the forearms supported and with less flexion of the upper arm. Surface electromyographic measurements also confirmed that the changes were ergonomic improvements.     

Using computational fluid dynamics to modify a waste-heat boiler design

This article describes the use of a general-purpose computational-fluid-dynamics code for improving and optimizing waste-heat boilers in the Outokumpu flash smelting process. The codes offer opportunities to study the transport phenomena for fluid and particulate flow and heat and mass transfer. The simulation includes gas- and dust-flow behaviors and gas cooling by convection and radiation. The results were used in the boiler modification for increased capacity and higher cooling efficiency. The modified boiler, with its unique design, has been in use at Outokumpu’s Harjavalta copper smelter since June 1995 with excellent performance. For more information, contact Y. Yang, Delft University of Technology, Raw Materials Technology/Applied Earth Sciences, Mijnbouwstraat 120, Delft, 2628 RX, Netherlands; telephone 31-15-278-2542; fax 31-15-278-2836; e-mail Y.Yang@ta.tudelft.nl.