Listing “ALL” Delayed Coke Unit process licensors is a tall order since nearly all the major refiners or process unit vendors have developed patents on improvements in one aspects or are of DCU.
But some of the major players are Foster Wheeler, ConocoPhillips, Sinopec Engineering, ExxonMobil, CB&I/Lummus, Petrobras and Bechtel or ABB.
Foster Wheeler sites over 80 refineries it has licensed from 1977-2009 (I have only counted 62 thusfar but some might be drum replacements & licensing that are not on their contract list and they have not posted all cokers still in Planning/Feed process for 2010-2015 yet).
ConocoPhillips has over 47 refineries it has licensed since 1982-2009 (their site has list but like FW some next cycle are not posted yet) and they also operate over 15 of their own coking refineries which use or were converted to use DCU after being acquired.
ExxonMobil has Fluid/Flexicoking continous process which they have licensed in over 22 refineries (~9 now S/D, 6 are Flexicokers counting new Hellenic coker 2008, 7 are Fluid cokers – including the 3 upgrade Fluid cokers at Syncrude).
They also have some patents on the DCU process (ie Mobils waste oil injection) but not on full DCU coking process.
Sinopec Engineering has DCU process which they have done on nearly all the Chinese Government owned refineries for Sinopec/ PetroChina which counts over 43 DCU sites (may also have done it for the nearly 44 independent coking refineries but I am not sure about that). However many of the new Joint Venture refineries with MidEast or global refiners are using some the western DCU licensors now.
Petrobras developed their own DCU process in Brazil for many of their own existing DCU units (~5 cokers) and few to other countries but several of newly completed or now in EPC process will be using either FW or COP licenses.
Several other global refineries like Shell, Chevron, Total, and ect also have patents on some aspect of the DCU process or a combined process using one alternate process to coking. But I do not believe they are providing a complete DCU process license in competition with major players.
CB&I/Lummus has their own DCU process now – CBI was major coke drum supplier previously and they acquired Lummus which also had a DCU process the combined company became more active in this area. I am not sure of total Lummus licenses but believe it is on order of XOM or Petrobras count.
Many of the Engineering or EPC companies like Bechtel (sometimes partner with COP), ABB, Fluor and others sometimes also do DCU process license but do not comprimise their relationship with the major DCU licensors.
CB&I (since 1969 ~120 drums) , SHI (Sumitomo Heavy Industries ~160 drums since 1985) have been the major coke drum suppliers with newcomers like Mangiarotti (6 drums since 2000) now providing coke drums for process.
Hope this helps