NEW DOWNLOAD (January 2007)

Coal & Biomass Handling

Currently the UK’s thermal power generation industry is experiencing considerable change largely brought about by an environmentally driven move away from coal as a single source fuel to co-firing with solid biofuels.

This paper examines the downside risks associated with (i) coal/solid biofuels mixtures that are more difficult to handle than coal alone, which may result in a reduction of free flow capability in the existing design of unit bunkers and (ii) solid biofuels, whose physical and flow property basis for free flow bunker design is hardly known resulting in a highly probable reduction of anticipated free flow capability in the storage bunkers that are currently being built.

© Copyright Dr H Wright & Associates 2004. (IMechE Conference ''Power Stations: Optimising the Return on the Asset”, 29/30 November 2004, London)

Improving the Free Flow Capability of Power Station Bunkers

© Copyright Dr H Wright & Associates 1995. Printed in bulk solids handling, Vol 15 1995 No 3)

Although this paper is some 11 years old, the analysis of coal flow failures carried out at Drax Power Station over the 9 month period June 1993 to February 1994 has been foundational in improving unit bunker flow at Drax and in other UK stations including Eggborough, West Burton and Tilbury.

Whilst other stations have yet to appreciate the benefits of "bathtub" flow, the quite recent investment into "gravimetric" (weigh belt) feeders at Kingsnorth, Tilbury and Longannet is doubly beneficial as the bathtub flow improvement profiling is built-in at the discharge belt level.

Essentials of Bunker Design

Copyright Wilkinson & Wright 1985
(ISBN 0 95095973 1 3)

This publication focuses on the design of bins, hoppers, bunkers and silos from the viewpoint of flow, although structural design aspects are not ignored.

The Use of Novel & Diagnostic Design Techniques to Eliminate Coal & Ash Storage Failures

Copyright Dr H Wright & Associates 2000
(IMechE Power Station Maintenance Conference, St Catherine's College, Oxford, UK 18 - 20 September 2000).

This paper highlights six areas of conceptual applications engineering where, over the last decade, the use of (i) novel diagnostic and (ii) retrofit design techniques has provided solutions aimed at the elimination of coal and ash storage failures.

The novel diagnostic tools outlined relate to (a) Representation of any new or existing design of mass or core (funnel) flow bin, hopper, bunker or silo, by a unique graphic flowability criterion, (b) On-line coal handleability indices, (c) Diagnostic use of archive plant operating data enabling the assessment of unit bunker coal flow failure rates and (d) On-line laser scanner identification of bunker flow regimes to avoid ratholing and blow-backs.

How High-Tech Fossil Fuel Handling Can Minimise Profit Loss

Copyright Dr H Wright & Associates 2001
(IMechE Seminar "Retrofiting Steam Power Generation Plant for Improved Performance, London, UK 26th September 2001. Reprinted in bulk solids handling, Vol 22 2002 No 1)

The main reason why profits are not maximised in retrofit projects on power plants is the widespread and continuing misconception that materials handling is low-tech in comparison with the high-tech of steam generation plant.

With small changes in the feedstock or the properties of the feedstock, the guarantees of heatrate availability are immediately at risk. However, the cost of this high-tech knowledge is not great compared to the cost of lost revenue.

Development of a Monitoring System for Coal Flow in Bunkers

Copyright DTI 2000. Project Summary 247 - Cleaner Coal Technology Programme. DTI Publication URN 00/748.

Measurement of coal levels in power station bunkers is required to schedule filling and to avoid maximum and minimum levels being exceeded. The surface profile changes as the level falls, depending on: bunker/feeder design, lining material, conditions of the bunker and the flow characteristics of the coal. The coal may tend to drop preferentially to one side or corner, or core (funnel or "ratholing") flow may occur, usually above the feeder inlet. Devices have been used to measure the level in bunkers but a number of them are needed to cover adequately the surface and give a good chance of picking up the lowest level in the bunker.

This DTI Summary describes work carried out at Eggborough power station to test and develop novel, cost-effective laser scanning technology that provides real-time on-line data on the surface profile of the coal in the bunker.



*These publications are offered to the public for information only. Any information taken from them shall be verified by the user before incorporation into any design.