Ryan/Holmes process

Chevron s Sacroc project (Parro, 1984 Schendel and Nolley, 1984) and Amoco s Central Mallet unit (100 MMscfd, 85% CO2) (Anon., 1985) used membranes. However, the Sacroc project predates the Ryan Holmes process, and Amoco was under contractual obligation to supply gas with NGL s still present to a downstream NGL extraction plant. Therefore in the mid-1980s, the market generally sustained the conclusion of Goddin (1982) that, when NGL was recovered, economics favored cryogenic distillation over the use of either membranes or amine treating in C02-flood EOR projects. 

Hydrogen Purificalion, 1338 The CNG Process, 1342 The Ryan/Holmes Processes, 1342 Nitrogen Removal from Natural Gas, 1344... 

The Ryan/Holmes processes represent a family of related techniques for recovering carbon dioxide and hydrocarbon liquids from carbon dioxide-rich gas streams. They are licensed by Process Systems International, Inc. The processes incorporate low-temperature distillation with a circulating natural gas liquid (NGL) additive. Their primary field of application has been in the processing of gas from enhanced oil recovery (EOR) projects. The technology has been described by Process Systems International, Inc. (1992) Wood et al. (1986) Ryan and O Brien (1986) Schaffert and Ryan (1985) and Ryan and Schaffert (1984). 

Figure 16-19. Simplified flow diagram of Ryan/Holmes process fbr removing and recovering hydrocarbons, H2S, and CO, from natural gas or associated gas from enhanced oil recovery projects Process Systms. MemaBonal, 1992. Reproduced with permission tmm Hydrocatm Processing,/iird 1992...

In 1992, it was reported that there were nine licensees for the Ryan/Holmes process for plants ranging in size from slightly over 1 to 290 MMsefd (Process Systems International, Inc., 1992). 

The Ryan-Holmes distillation process uses cryogenic distillation to remove acid gases from a gas stream. This process is applied to remove COi for LPG separation or where it is desired to produce COt at high pressure for reservoir injection. This complicated process is beyond the scope of this book. 

Ryan-Holmes A cryogenic extractive distillation process using liquid carbon dioxide, in which a light hydrocarbon is added in order to suppress the freezing of the carbon dioxide. Licensed by Process Systems International nine licenses had been granted by 1992. 

A simplified flow diagram of one version of the Ryan/Holmes technology is shown in Figure 16-19. In a typcal application of the process for carbon dioxide-rich EOR gases, the feed gas stream is first passed through a separator (I) to remove any liquid water or hydrocarbons, then compressed to 360 psig (2), and dehydrated in a conventional glycol or molecular sieve unit (3). 

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