The British Gas Lurgi slagging gasifier is a counter-current
fixed bed gasifier operating at high pressure. Coal
descending the gasifier is pyrolysed to form coke which is
then gasified. Properties of such coke affect the gasifier
in its efficiency of operation. This thesis describes
a) the carbonisation of cokes from coal under simulated
gasifier conditions, b) the characterisation of the
resultant cokes in terms of structure and physical
properties and, c) the formulation of relationships between
coal thermoplasticity and coke properties.
Three high-volatile bituminous coals
Manvers Barnburgh NCB 702, and Gedling
(Manton NCB 502,
NCB 802) were
carbonised in an autoclave under a range of pressures (0.5-
8.0 MPa), using two different heating regimes, shock heating
to 700 °c and slow heating to 700 °c at 5 °C/min. Physical
characterisation of the resultant cokes was carried out
using optical and mechanical techniques.
Optical anisotropy and image analysis were used to determine
coke structure and porosity respectively. Tensile strength,
microstrength and abrasion resistance were measured to
establish the cokes' resistance to various forms of
breakage. High pressure dilatometry and plastometry were
used to measure the effects of pressure and heating rate on
coal thermoplastic properties.
Relationships between coal thermoplastic properties and coke
properties are very complex.
This work has shown that these relationships are highly
dependent on carbonisation
conditions with heating rate rather than pressure being the
more dominant parameter.
A Doctoral Thesis. Submitted in partial fulfilment of the requirements for the award of Doctor of Philosophy of Loughborough University.