Thesis-1995-Strugnell.pdf (5.97 MB)
The influence of high heating rate hydropyrolysis on the primary devolatilisation of coal
thesis
posted on 2013-11-21, 08:50 authored by Brian StrugnellThe hydropyrolysis of coal is considered to be an attractive future route for the
conversion of coal to gaseous and liquid fuels and chemical feedstocks. This thesis
comprises a study of the behaviour of coal under the conditions pertinent to those
envisaged within a commercial hydropyrolysis process, that is, using pulverised coal,
a short coal-reactor residence time, high hydrogen pressure and high heating rate. For
this purpose, an electrically heated grid apparatus has been used. The experimental
conditions have been weighted towards achieving a maximum loss of primary volatile
products whilst minimising unwanted and poorly controlled secondary reactions such
as char hydrogasification. In this way, it has been possible to compare the influence
of a hydrogen atmosphere on primary devolatilisation for a range of coals.
Overall, the total volatile release is enhanced by hydropyrolysis to a degree dependent
upon the partial pressure of the hydrogen. The increased yield is due mainly to an
increase of saturated hydrocarbons, although the production of some individual
species such as carbon monoxide, carbon dioxide and unsaturated hydrocarbons are
diminished with respect to helium pyrolysis. The magnitude of both total and
individual product yields vary with coal type, as does the degree by which these
yields are influenced by a hydrogen atmosphere. This influence is considered to
depend specifically on the type and number of various reactive sites and
functionalities within coal and also on their accessibility for hydrogen, which is in
tum dependent upon the thermoplastic behaviour of the coal. A further factor
governing both product yields and hydrogen influence is the coal petrographic
composition. Inertinite macerals have been observed to be significantly more
responsive than exinite or vitrinite to hydrogen, producing relatively high methane
yields. Thus it has been shown that inertinite rich coals or enriched feedstocks may be
suitable candidates for hydropyrolysis processing.
The data obtained have also demonstrated how a number of coal properties obtained
by standard analytical techniques may be used for coal selection and yield prediction.
BS volatile matter, carbon content, vitrinite reflectance and both 0/C and H/C atomic
ratios are the most useful of the properties investigated in this respect. This is
considered to be an important step towards the foundation of a classification system
for hydropyrolysis processing.
History
School
- Aeronautical, Automotive, Chemical and Materials Engineering
Department
- Chemical Engineering
Publisher
© Brian StrugnellPublication date
1995Notes
A Doctoral Thesis. Submitted in partial fulfilment of the requirements for the award of Doctor of Philosophy of Loughborough University.EThOS Persistent ID
uk.bl.ethos.295542Language
- en