Edward Lester

Characterization of coals for combustion using petrographic analysis: a review

Abstract Petrographic analysis can give useful information about the combustion of pulverized coal. However, the relations between maceral types and reactivity are not simple; for example, not all inertinites are inert, and not all vitrinites are reactive. This is a consequence of the formal definition of macerals and the variations between coals from different parts of the world. The reflectance values of the maceral groups and the associations of the different macerals, determined as microlithotypes, also need to be taken into account. Mineral matter also has an effect on the type of char formed, and the situation is further complicated by the different char characterization schemes in the literature. The main conclusion from this review is that any predictive system needs to take all these factors into account, especially reflectance.

Instant MOFs: continuous synthesis of metal-organic frameworks by rapid solvent mixing.

A continuous flow reactor allows the preparation of porous metal-organic framework materials with crystallisation induced by rapid mixing of streams of preheated water and solutions of reagents in organic solvent: this gives high volume production (132 g h(-1)) with crystallite size of the products from nanoscale to micron.

Char characterisation and its application in a coal burnout model

In this study, char image analysis techniques have been employed to investigate the morphology of chars obtained from a Drop-Tube furnace. Char image analysis results have been incorporated as inputs to a char burnout model based on Hurts CBK model. It has been observed that the char combustion rate was strongly affected by char structural parameters and the inclusion of char morphology has led to a better prediction of char burnout. It has also been suggested by the model that the inclusion of ash inhibition overestimates the resistance attributed by ash film and the consideration of ash film resistance should be undertaken in a different way to give a better prediction at the later stages of char combustion.

Characterization of coal with respect to carbon burnout in p.f.-fired boilers

Abstract Carbon burnout, measured as percentage combustibles remaining, was determined for 16 world coals on a 1 MW p.f. combustion rig. The combustibles-remaining figures were correlated with parameters such as ash yield, carbon content, fuel ratio, rank, reactive macerals content and a reactivity parameter determined from a grey-scale histogram obtained by image analysis of the coals. The reactivity parameter was found to give a good correlation with combustibles remaining, far superior to the correlation given by any other parameter. Char samples collected at various points in the combustion rig confirmed that the intrinsic reactivity of char decreases during the combustion process and that the morphology of the char produced during the very early stages of combustion has a much greater effect on carbon burnout than intrinsic reactivity does.

Nickel incorporation into a hollow fibre microporous polymer: a preparation route for novel high surface area nickel structures

Abstract The incorporation of Ni metal into PolyHIPE (a generic hollow fibre polymer produced by emulsion polymerisation) was attempted by both electroless deposition and electrodeposition and the resulting composites were characterised by a Scanning Electron Microscope (SEM) and Energy Dispersive Analysis by X-ray (EDAX) analysis. The first method produced a conducting outer surface coating which did not penetrate significantly into the interior of the polymer. Electroplating succeeded in growing Ni through the polymer cells and pores. Subsequent burning out of the polymer matrix resulted in a granular interconnected Ni structure with a specific surface area of 49.5 m2 g−1, suggesting that Ni coatings produced by this method could be an alternative to Raney-nickel coated electrodes.

Preparation of polymer–nanoparticle composite beads by a nanoparticle-stabilised suspension polymerisation

A novel strategy based on nanoparticle-stabilised suspension-polymerisation has been achieved for the preparation of hybrid nanocomposites in the absence of any conventional stabiliser. By using this in situ polymerisation technique, functional nanoparticles can be immobilised onto the surface of polymer beads to significantly modify their properties. In this paper, Fe3O4 nanoparticles are used as stabiliser for the suspension polymerisation of methyl methacrylate (MMA) in water. Magnetic Fe3O4–PMMA nanocomposite polymer particles have been successfully synthesised. The experimental results show that the Fe3O4 nanoparticles are uniformly distributed on the surface of the spherical polymer beads.

A continuous and clean one-step synthesis of nano-particulate Ce1−xZrxO2 solid solutions in near-critical water

Gram-scale quantities of microcrystalline powdered CeO2–ZrO2 solid solutions can be produced continuously in a near-critical water flow reactor at ca. 300 °C and 25 MPa; rapid hydrothermal co-precipitation leads to nano-particulate Ce1−xZrxO2 (x = 0 to 1), the composition of which is merely determined by the initial concentrations of Ce4+ and Zr4+ ions in the starting solution.

The structure and reactivity of density separated coal fractions

Density separations of six world coals have been carried out. The coals were provided as pf samples and were screened to provide size fractions at -38 + 20 μm from which tight density fractions (0.02 and 0.03 g cm -3 intervals) were produced in a heavy liquid medium using the float-sink procedure. Each density fraction was characterised by manual maceral analysis and a new automated image analysis technique called the reactivity assessment program. The chemical structure of each fraction was examined by 13 C n.m.r. and FT-i.r. spectroscopies. The reactivity of the density fractions was assessed using a drop tube furnace at a temperature of 1300°C, residence time of 100 ms and 1 vol% oxygen atmosphere. The morphology of the chars produced in the drop tube furnace were examined manually and using an automated image analysis technique. This allowed the predicted reactivity of the fractions to be correlated against actual burnout characteristics.

The Rapid Size- and Shape-Controlled Continuous Hydrothermal Synthesis of Metal Sulphide Nanomaterials

Continuous flow hydrothermal synthesis offers a cheap, green and highly scalable route for the preparation of inorganic nanomaterials which has predominantly been applied to metal oxide based materials. In this work we report the first continuous flow hydrothermal synthesis of metal sulphide nanomaterials. A wide range of binary metal sulphides, ZnS, CdS, PbS, CuS, Fe(1-x)S and Bi2S3, have been synthesised. By varying the reaction conditions two different mechanisms may be invoked; a growth dominated route which permits the formation of nanostructured sulphide materials, and a nucleation driven process which produces nanoparticles with temperature dependent size control. This offers a new and industrially viable route to a wide range of metal sulphide nanoparticles with facile size and shape control.

Preparation of hybrid polymer nanocomposite microparticles by a nanoparticle stabilised dispersion polymerisation

We report the use of nanoparticles to stabilise free radical dispersion polymerisations, without the need for any conventional stabiliser, leading to the preparation of polystyrene nanocomposites. The products are well characterised spherical polymer microparticles decorated with nanoparticles on their surfaces. In this paper we demonstrate the process with Fe3O4nanoparticles yielding a product with a strong magnetic property. By using this in situpolymerisation technique, not only can nanoparticles in aqueous solution be harvested, but also this provides a completely new route to polymer composites. Thus, functional nanoparticles can be immobilised onto the surface of the polymer beads to modify significantly their properties.