A month ago Monday (MNM Week 26) we reported the very successful 6th Annual EuroFlam Seminar, organised at Cardiff University on Wednesday 23rd and Thursday 24th June. There, Visiting Investigators from the three EuroFlam members, ENEL SPI, IFRF and Cardiff University, met together during the two days to present their reports on the projects that they had carried our during the previous year.

This group was augmented by a small number of visiting investigators, who are presently in residence and have carried out a substantial part of their project.

This week, in this  Volume 4, we are publishing the last series of abstracts of the presentations made at the Seminar.

Abstract
IFRF renewed its interest in using the Narrow Angle Radiometer probes, recently. During the last trials, the experiments showed that the probes were difficult to use. It seemed necessary to improve the existing probe design. Thus, Narrow Angle Radiometer probe has been redesigned and the experiments demonstrated that the modifications substantially improve the performance of the probes. However, these experiments also revealed that the viewing angle is larger than expected and the repeatability of the measurements is poor when the instrument is equipped with small diameter collimating tubes. These new results spurred to conduct a more thorough investigation of how the NAR probe works. The improvements to the original design will be reviewed in this presentation. Then, a practical use of the probe in semi-industrial scale experiments will be shown.

Abstract
Since 1987, the IFRF (IJmuiden, The Netherlands) has been using the Fluent computer code as a basis for computing of pulverised coal flames. Over this time period, substantial modifications to the standard Fluent code were made with respect to combustion of pulverised coal in turbulent diffusion flames. The aim of the IFRF user defined subroutines is to provide a Fluent user with an extension to the standard code specific to pulverised coal combustion. Because to such a specificity, pre--processing can be simplified and adapted to combustion engineers requests. Furthermore, post--processing can be significantly extended by making available additional field quantities related to pulverised coal combustion. To model pulverised coal combustion, use is made of one of the standard user-particle-laws subroutines. The IFRF particle law subroutine covers particle heating/cooling, devolatilization, char combustion, coupling of the char combustion rate to the gaseous phase combustion rate and ash tracking.

During my stay at the investigations were made to improve the IFRF subroutines with regard to the char burnout and the devolatilization. The changes in the subroutine were verified in a calculation for the IFRF isothermal plug flow reactor.

First of all the presentation starts with a short introduction in the basics of coal combustion and its modeling. In a further section the results are shown and discussed.

Abstract
We have developed an instrument, named MITER 1900, for the on-line determination of the unburned carbon content (UCC) in coal fly ashes.

A sensor, placed at one end of the directional coupler, measures the reflected part of microwave power. At the other end of the directional coupler there is a microwave cavity. A quartz pipe is placed along the cavity’s axis. Ash samples are introduced in the pipe and then placed into the cavity.

Moving the partially loaded pipe along the cavity axis, it is possible to change the quantity of the sample seen by the cavity. Two modes are resonant in the cavity: the TM010 and the TE111.

Using some parameters related to the resonant peaks of the TM010 and of the TE111, it is possible to calculate the unburned carbon content of the ash sample.

It is important to study the characteristics of resonant peaks with different ash quantities because the signal saturation is avoided and so unburned carbon content can be measured in a wide range.

Using different ash samples with different UCC, it was possible to combine the mentioned parameters so that the unburned carbon content was measured without any reference to the parent coal. Therefore, instrument calibration is not necessary with this approach.

In order to determine the unburned carbon content with a better accuracy (± 0.5%), it is possible to use only one parameter related to the resonant peaks. However in this case the calibration is necessary employing at least two ash samples characterised in lab.

Abstract
The need to research new co-generation systems for electricity production is an obvious fact in the view of the increase of energy demand. It is also justified for the low use of the waste and biomass resource, which is about 14% of the world energy resources. Moreover, these systems imply an improvement on the environment, since that energy source is a carbon neutral cycle. In this context the EU has initiated the use of wood gasification/turbine systems for the production of heat and power. The aim of Cardiff University has been to examine the use of an inverted cyclone gasifier to produce a good quality wood gas for further combustion in a turbine. This work is part of this study.

The aim of the present work was to characterise the movement of the flow inside of an inverted cyclone gasifier, under isothermal conditions, wich means with cold flow. This characterisation consisted on calculating the velocity of every point of the flow for three different flow rates (1000 l/min, 2000 l/min and 3000 l/min) which were calculated in order to obtain stoichiometric conditions with a estimated feed rate of 50 kg of wood powder per hour. These velocities were expressed in cylindrical co-ordinates. To obtain axial and tangential velocities Laser Doppler Velocimetry (LDA) measurements were taken. Radial velocities were calculated with data obtained using Particle Image Velocimetry (PIV) . At the same time with this system, PIV, tangential velocities were obtained. and used to compare with the results from LDA.

The study of the inlet design was also investigated because of the necessity of increasing the tangential velocity to improve the separation process. Three different inlet configurations were checked: with the total area of the inlet, with a third and with half the area blocked. The effect of these different configurations on the movement of the flow and on the static pressure was studied. The most favourable configuration was with a third of the inlet blocked.

The results obtained with LDA in every case of combination of flow rate with type of insert were showed with contour plots and curves. The repeatability of the trend shows the consistency of the results. The PIV results were also contrasted and the same pattern was founded in every level.

The Future work that has to be developed consists on the study of the flow under combustion conditions. A further work will be to study the system with wood powder, analysing, finally the efficiency of the process.

This periodical forms part of the group of publications owned by the IFRF
The IFRF Monday Night Mail is published by:
IFRF NET, P O Box 10,000, The Netherlands
Edited: Peter Roberts
ISSN 1562-4781