Jon – I am not sure what area you are interested in but rather than book, take a look at several reports from coking industry.
CIA (coke drum inspection folks) have few links at their website like one PDF’s from GLC on Fundamentals (bit dated ~1999) @ http://www.cia-inspection.com/DECOKTUT.PDF
Also one on Coking Fundamentals from University of Tulsa that has Delayed Coking Research going on (note the PDF can only be printed not saved) @ http://www.osti.gov/bridge/purl.cover.jsp;jsessionid=829D63B962242FA5869C71C8EE1DEEB8?purl=/902707-2bwFJ6/
A lot of the text books on coker fundamentals are more for design folks than operational types & often either too simplistic to be of much use in the field, or too much along theory lines.
There was one handbook a lot of troubleshooters/cost estimators use but I only have very old copy of it ….somewhere : Refinery Operating Cost by WL Nelson.