Developments in Humidity Standards and the Psychrometer Equation

Determination of the wet-bulb temperature at the surface of a material is the basis of one class of humidity measuring instruments, and is important in industrial applications such as dryer modelling and simula tion. The psychrometer equation is a frequently used method of estimating wet-bulb temperature, and contains a psychrometer"constant". Analysis shows that this is in fact a variable coefficient affected by temperature, pressure, radiation and conduction effects, and the identity of the gas and vapour. Radiation and conduction affect the difference between adiabatic saturation temperature and indicated wet-bulb temperature. Inconsistencies in currently recommended values for the psychrometer coefficient, including published international standards, are identified and explained. Particular problems arise when the enhancement factor is applied to vapour pressure to account for non-ideality of gases. Special considerations are also needed for wet-bulb temperatures approaching the boiling point, where     

The Effect of Intense Air Drying on Material Distribution and Quality in Coated Papers

The aim of this study was to find out what will happen to paper coating quality and material gradients if coating is dried in one air dryer at a high convection rate (150 kg/m²h). Different printing papers were coated, calendered and printed with pilot machines. The binder and pigment gradients of the coated, and also printed, samples were analyzed with LIPS (Laser Induced Plasma Spectrometry). It was found that drying affects the migration of starch, but not latex. Total air drying can be used to dry printing papers, if air temperature, velocity and moisture content can be separately controlled. The control of web temperature is more important for paper quality formation in a coater drying section than that of evaporation rate.     

Successful Implementation of a Nation-Wide Load Management System

This paper describes a load management program successfully implemented in Sweden. There is today an excess supply of electric energy in Sweden mainly due to the fast developement of nuclear power. This has resulted in a temporary situation with excess low-cost hydro and nuclear power. To take advantage of this situation, a complete load management system based on a personal computer was designed in a very short time. The main part of the paper describes different aspects of the system developed. The paper give in addition some operational experiences and concludes by addressing how the system can be used in the future, when the temporary excess supply situation is over.     

Erfahrungen bei Planung und Betrieb der mechanischen Probenahmeanlagen in den Häfen der Luossavaara-Kiirunavaara AB (LKAB)

Beschreibung der mechanischen Probenahme und Probenaufbereitung bei der Schiffsbeladung in den Häfen der LKAB. Ausführungen über eine neue Probenahmeanlage im Erzhafen Narvik. Angaben über die entnommenen Mengen der Proben aus dem Förderstrom für die chemische Analyse, Nässebestimmung und Siebanalyse in den Erzhäfen Narvik und Luleå.