Overview of Refinery Gasification

Gasification has a long history of research, development and commercialization stretching back more than 50 years. Over 129 plants have been constructed and operated worldwide, and as many as 34 new plants are in various stages of planning and construction [1]. The majority of the existing plants were constructed for the production of synthesis gas or syngas, a mixture containing carbon monoxide (CO) and hydrogen (H2), used in the manufacture of a wide variety of chemicals. The wide range of uses for syngas is depicted in Figure 1. The second largest application has been the production of liquid fuels via the Fischer-Tropsch synthesis. Almost all of these units are located in South Africa, although future plants may be built in a variety of locations around the world for the conversion of stranded natural gas to liquid fuels. Near-term development of gasification technology is focused on the clean production of electric power. This application has been the subject of a number of commercial ventures and demonstrations in recent years. Within the U.S., major demonstration projects supported by the DOE have been sited at Tampa Electric’s power station in Polk County, FL (1996) and Global Energy’s Wabash River station in Indiana (1995). These projects have been based on coal and employ Integrated Gasification Combined Cycle (IGCC) plant configurations. Petcoke has also been tested in these facilities. Commercial applications worldwide have focused on petroleum refining, many involving the trigeneration of hydrogen, power and steam. Recent projects include U.S. refineries in El Dorado,KS (Frontier Oil, formerly Texaco), Coffeyville, KS (Farmland Industries), Delaware City, DE (Motiva), and Baytown, TX (ExxonMobil); and European refineries in Falconara, It. (API), Sicily, It. (ISAB), Sardinia, It. (Sarlux), and Pernis, Neth. (Shell). These refinery applications are the main focus of this report.

Possible Products from Synthesis Gas

Combined Heat & Power Generation

Hydrogen

FT Syncrude

Methanol

&

Higher Alcohols

SynGas

To Hydrogenations (pet refining & other)

To Hydrocracking

To Ammonia Synthesis

Possible Fuel-Cell Fuel

To Oxo Chemicals &

Derivatives

Possible Fuel-Cell Fuel

MTBE

Formaldehyde

DME

Acetic Acid

Acetaldehyde

Acetic Anhydride

Chloromethanes

DMT

MMA

Methyl Amine

Urea (fertilizers)

To Refinery Upgrading

To Naphtha Steam Cracker

Alpha Olefins

Lube Oil Base Stock

Specialty Waxes

Gasoline &

Diesel Fuel

Ethylene &

Propylene

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A wide variety of feedstocks can be considered for gasification, ranging from solids to liquids to

gaseous streams. Although when the feed is a gas or liquid, the operation is frequently referred to as

partial oxidation (POX). From a process perspective, partial oxidation of gases and liquids is very

similar to the gasification of solids. The term “gasification” will be used to refer to all these applications

within this report. The major requirement for a suitable feedstock is that it contains a significant content

of carbon and hydrogen. Solid feedstocks include coal, petcoke, biomass, and other solid waste

streams. There are many hydrocarbon containing gas and liquid streams that may be used as a

feedstock for gasification. However, the streams most commonly employed are generally low-value byproducts

or waste streams generated by other processes. Refinery feedstocks often considered are

process off-gas streams and residual oils such as vacuum resid, visbreaker tar, and deasphalter pitch.

These residuals are often referred to generically as “heavy oils.” This report develops profile data for

both petcoke and heavy oils. Table 1 lists typical compositions and properties of these feedstocks.

Refinery off-gases are not considered here.

Table 1. Typical Feedstocks for Refinery Gasification

Major developers/licensors of gasification technologies include ChevronTexaco, Shell, Global Energy

and others. Each of these technologies has its own unique features, which are discussed briefly later in

this report. The profiles developed here are primarily based on the Texaco quench gasification process.

Supporting technologies include air separation, acid gas removal, hydrogen separation and combinedcycle

power generation. All major commercial applications of gasification technology have relied on

Units

Vacuum

Resdiude

Visbreaker

Tar

Asphalt Petcoke

Ultimate Analysis

C wt/wt 84.9% 86.1% 85.1% 88.6%

H " 10.4% 10.4% 9.1% 2.8%

Na " 0.5% 0.6% 0.7% 1.1%

Sa " 4.2% 2.4% 5.1% 7.3%

O " 0.5% 0.0%

Ash " 0.0% 0.1% 0.2%

Total wt/wt 100.0% 100.0% 100.0% 100.0%

H2/C Ratio mol/mol 0.727 0.720 0.640 0.188

Density

Specific Gravity 60o/60o 1.028 1.008 1.070 0.863

API Gravity oAPI 6.2 8.88 0.8 -

Heating Values

HHV (dry) M Btu/lb 17.72 18.6 17.28 14.85

LHV (dry) " 16.77 17.6 16.45 14.48

a Nitrogen & sulfur contents vary widely.

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cryogenic air fractionation processes; however, novel membrane separation-based technologies are

currently under development for this application. Major suppliers of cryogenic air separation unit

(ASU) include Air Liquide, Air Products & Chemicals, Linde and Praxair. A wide variety of acid gas

removal technologies have been employed. Major providers of these technologies include Lurgi and

UOP. UOP is also a major supplier of hydrogen purification technologies. Gas turbine technologies

used in combined-cycle power generation systems are available from General Electric and

Siemens/Westinghouse.