p.1 

OAR Box 1828 

Prepped by Ollie Stewart 

Document Number: 

300) IV-A-10 

Docket Number: 

A-83-27 

Printed 11/12/2008 11:12:59 AM Sheet 300 of 325 
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A-83-27 

IV-A-10 

PRODUCTION OF 

VERY LOW-SULFUR RESIDUAL FUEL OILS 

Prepared by: 

David White and Edward Moretti 

Radian Corporation 

P.O. Box 1300 

Research Triangle Park, NC 27709 

Prepared for: 

Fred Porter 

Standards Development Branch 

Emissions Standards and Engineering Branch 

Office of Air Quality Planning and Standards 

U.S. Environmental Protection Agency 

Research Triangle Park, NC 27711 

April 10, 1987 
PRODUCTION OF VERY LOW-SULFUR RESIDUAL FUEL OILS 

SUMMARY 

This study briefly reviews petroleum refining technologies and supply 

data associated with production of very low-sulfur residual oils (VLSRO, 

defined as residual oils containing 0.3 percent sulfur or less). Of specific interest is the use of residuum hydrodesulfurization (RHDS) technology 

to produce VLSRO. Information reviewed in the study includes both published 

literature and telephone conversations with oil company personnel and 

desulfurization technology vendors. The primary conclusions that emerge 

are as follows: 

• Most U.S. petroleum refineries are designed to maximize the production of "high value" petroleum products such as transportation 

fuels, distillate oils, and petrochemical feedstocks. As a result, 

a substantial portion of the lower value products such as residual 

oil is "upgraded" to these higher valued products rather than sold 

as residual fuel oil. As a result, the U.S. imports about one-half 

of its total residual oil supply from other countries. More 

importantly, oyer three-fourths of the U.S. supply of VLSRO 1s 

imported. 

• VLSRO can be produced by either RHDS of high-sulfur residuum or 

distillation of yery low-sulfur crude oil. Because of the high 

sulfur, nitrogen, and metals contents in most residuums, RHDS. 

requires substantial amounts of hydrogen and catalyst. The least 

cost approach for producing VLSRO depends on the cost premium for 

very low-sulfur crude oils relative to the processing cost for 

desulfurizing higher sulfur residuum. 

• Currently, it is cheaper for U.S. refineries to produce VLSRO 

through distillation of very low-sulfur crude oils than by RHDS 
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of residuum produced from medium- and high-sulfur crude oils. As a 

result, most existing RHDS capacity in the U.S. is currently being 

used to produce high value products such as gasoline and diesel 

fuels. 

t ^lery few foreign refineries exporting VLSRO to the U.S. have RHDS 

capacity. As a result, most VLSRO imported into the U.S. is 

produced by distillation of very low-sulfur crude oils. Two major 

exceptions are refineries in Venezuela and the Virgin Islands; these 

two locations accounted for roughly 20 percent of the total U.S. 

supply of VLSRO in 1985. 

t The use of distillation to produce most VLSRO reflects current 

supply and demand economics in the world oil market. If crude oil 

sulfur premiums were to increase or supplies of very low-sulfur 

crude oils were to be constrained by resource limitations, political 

actions, or other factors, the economics of RHDS would improve. 

• Given these uncertainties, it 1s difficult to predict the extent of 

RHDS that will occur in the future. However, it is expected that 

distillation of very low-sulfur crude oils will continue to 

represent a significant percentage of VLSRO production for the 

foreseeable future. 

RESIDUAL OIL REFINING OPERATIONS 

Residual fuel oil 1s produced from the heavy, high-boiling-point 

(650°F+) fraction (known as "atmospheric residuum") obtained during 

atmospheric distillation of crude oil (Figure 1). Atmospheric residuum can 

be further separated using vacuum distillation into vacuum gas oil (VGO, 

boiling point 650-1000°F) and vacuum residuum (boiling point 1000°F+). The 

long-chain hydrocarbons in these fractions contain a significant percentage 

of the sulfur, nitrogen, and metals (primarily nickel and vanadium) found in 

crude oil. Sulfur data for several selected crude oils and associated 
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Crude 

Oil " 

Gases _ 

T) atlo II Ist 

o 

Q. 

.C 

o 

E 

<. A 

Naptha 

Kerosene _ 

Gas Oil _ 

Sulfur Recovery 

Hydrotreating 

••LPG 

'—• » 

— * » 

Reforming 

Hydrotreating 

Hydrotreating* 

m. 

•—»> 

r ^ • ~ N |Atmospherlc 

Residuum 

• 

'acuu

m Distillation 

Vacuum fc 

Gas Oil "" 

• Hydrotreating* Catalytic 

Cracking 

easonne 

Blending 

—•» • Gasoline 

V 1 | Vacuum 

Residuum 

• Hydrotreating* Thermal 

Cracking 

Distillate 

Blending 

-- Jet Fuel 

—•Distillat e Oil 

1—•» 

Residual 

Blending —•»» Residual Oil 

—•» To Naptha 

Hydrotreating 

••Coke 

'optional depending on feedstock and product quality. 

FIGURE 1. SIMPLIFIED FLOW DIAGRAM OF U.S. PETROLEUM REFINERY 
P.6 

TABLE 1. WEIGHT PERCENT SULFUR IN SELECTED CRUDE OILS AND ASSOCIATED 

DISTILLATION FRACTIONS 

• 

Low-Sulfur Domestic 

So. Louisiana 

Coastal Texas 

Low-Sulfur Imported 

Algeria 

Angola 

Canada (Alberta) 

Denmark (North Sea) 

Indonesia (Sumatra) 

Nigeria 

Norway (North Sea) 

Zaire 

Other Imported Crudes 

Mexico 

Saudi Arabia (light) 

Saudi Arabia (heavy) 

Venezuela 

Crude 

Oil 

0.14 

0.20 

0.10 

0.17 

0.15 

0.20 

0.12 

0.14 

0.10 

0.12 

1.40 

1.90 

2.80 

2.50 

Atm 

Resid 

0.31 

0.30 

0.25 

0.23 

0.33 

0.40 

0.18 

0.30 

0.30 

0.18 

2.55 

3.20 

4.50 

2.90 

VGO 

0.24 

0.24 

0.17 

0.18 

0.25 

0.29 

0.14 

0.25 

0.26 

0.13 

1.90 

2.45 

3.00 

2.25 

Vac 

Resid 

0.31 

0.60 

0.30 

0.30 

0.54 

0.60 

0.23 

0.52 

0.50 

0.22 

3.60 

4.10 

5.50 

3.30 

Fuel 

Oil 

0.35 

0.37 

0.25 

0.23 

0.40 

0.40 

0.20 

0.34 

0.40 

0.18 

2.65 

3.20 

4.10 

2.55 

Source: Reference 1 

residuum fractions are presented in Table 1; crude oils that are relatively 

low in sulfur content are emphasized. Note that sulfur is significantly 

more concentrated in vacuum residuum than in the somewhat lighter VGO. The 

"fuel oil" column is a blend of processed residuum products. 

Depending on the gravity and composition of a given residuum fraction, 

the desired products, and the required product quality, it may be necessary 

to hydrotreat the residuum to remove sulfur, nitrogen, and metals before 

further refining. The technology and processing requirements associated 

with hydrotreatment of residuum are discussed later. 

Following hydrotreatment, vacuum gas oil is generally sent to a 

catalytic cracking unit where it is heated in the presence of a catalyst to 

convert the large VGO molecules into lighter, lower boiling point products 

such as gasoline and distillate oil. Vacuum residuum can also be catalytically cracked, but is more expensive to process due to its lower hydrogen 
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content, higher level of Impurities, and higher boiling temperature. 

Because of this higher cost, vacuum residuum is more frequently processed 

using thermal cracking. Thermal cracking involves the use of high 

temperature and pressure to produce either a mixture of lighter products and 

heavy, hydrogen-deficient coke (known as "coking") or a lower viscosity 

residual oil (known as "visbreaking"). 

Depending on residuum quality and the processing capabilities of a 

given refinery, low-sulfur residual oil can be produced 1) directly from 

low-sulfur crude oils, 2) by blending with gas oils or distillates to reduce 

sulfur concentrations and improve physical properties (e.g., viscosity), or 

3) by hydrotreating high-sulfur residuum. The relative economics and use of 

these different approaches are discussed later. 

RESIDUAL OIL SUPPLY AND DEMAND 

Reflecting the relative availability and economic value of various 

fuels, production of petroleum products in the U.S. has gradually shifted 

from distillate and residual oils used by industry and electric utilities to 

lighter products such as transportation fuels and petrochemical feedstocks. 

As a result, most U.S. refineries have Installed significant refining 

capacity to convert residuum to these lighter, higher valued products. 

The imbalance between residuum supply and residual oil production 

provides an estimate of the percentage of residuum upgraded to these lighter 

products. As shown In Table 2, crude oils processed by U.S. refineries 1n 

1984 contained an average of 16.3 percent atmospheric residuum and 0.96 

percent sulfur; for 1988 these values are projected to Increase to 17.0 

percent residuum and 1.06 percent sulfur. However, as shown in Table 3, 

residual oil accounted for only 6.0 percent of total refinery products in 

1984 and is projected to decline to around 5.5 percent by 1988. These 

figures suggest that only about one-third of the total residuum supply is 

ultimately sold as residual oil (based on 6 percent RO divided by 17 percent 

residuum). The decline in residual oil production between 1984 and 1988 

reflects the higher return on refinery investment associated with production 

of lighter, higher value petroleum products. The projected intense price 
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TABLE 2. AVERAGE COMPOSITION OF CRUDE OIL PROCESSED BY U.S. REFINERIES 

Crude Characteristic 

Total Quantity (MB/CD)a 

Specific Gravity (°API) 

% Residuum 

Avg. % Sulfur 

% < 0.5% S 

% 0.5-1.0% S 

% > 1.0% S 

Actual 1984 

11,642 

32.6 

16.3 

0.96 

50.5 

16.8 

32.9 

Projected 1988 

12,420 

31.7 

17.0 

1.06 

46.2 

16.1 

37.6 

a million barrels per calender day 

Reference 3, pp. 30-31. 

TABLE 3. PRODUCTION OF RESIDUAL OIL BY U.S. REFINERIES 

Characteristics 

Total Refinery Products (MB/CD) 

Total Residual 011 (MB/CD) 

% < 0.3% Sulfur RO 

% 0.3 - 1.0% Sulfur RO 

% 1.0 - 2.0% Sulfur RO 

% > 2.0% Sulfur RO 

Actual 1984 

13,920 

834 

5.2 

22.5 

36.5 

35.9 

Projected 1988 

14,499 

799 

4.5 

24.7 

40.9 

29.9 

Reference 3, pp. 33-35. 
P.9 

competition between natural gas and residual oil as a boiler fuel will also 

contribute to reduced residual oil demand and result in further upgrading of 

residuum to lighter products. Also note from Table 3 that VLSRO represents 

only about 5 percent of total U.S. residual oil production. 

In 1985, residual oil represented 7.6 percent of total U.S. petroleum 

2 consumption. Differences between domestic residual oil supply and demand 

historically have been satisfied by imports from foreign refineries. As 

shown in Table 4, 1985 residual oil imports accounted for roughly 43 percent 

of U.S. consumption after adjustment for residual oil exports (believed to 

be primarily high in sulfur content). For VLSRO, imports accounted for 

almost 76 percent of the total. 

TABLE 4. SUPPLY OF RESIDUAL OIL BY SULFUR CONTENT, 1985 

VOLUME (Thousand Barrels) 

Domestic Imported Total 

< 0.3% Sulfur 

0.3-1.0% Sulfur 

> 1.0% Sulfur 

Total 

a includes 72,060 thousand barrels of unknown sulfur content exported to 

other countries. 

Reference 2, pp. 55-56. 

RESIDUUM HYDRODESULFURIZATION TECHNOLOGY 

Residuum hydrodesulfurization (RHDS) is used to desulfurize and upgrade 

residuum for use as a feedstock in producing transportation fuels and 

distillate oils as well as to produce low-sulfur residual oil. RHDS 

involves mixing atmospheric or vacuum residuum with hydrogen and heating in 

the presence of a catalyst. Sulfur and nitrogen are converted to H2S and 

NH-. Excess hydrogen is removed in a high-pressure separator while H-S, 

NH~, and non-condensable hydrocarbon gases are removed in a low-pressure 

24,787 

82,969 

214,241 

321,997a 

78,201 

36,166 

71,917 

186,284 

102,988 

119,135 

286,158 

508,281a 
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separator. A portion of the metals removed during hydrotreatment adhere to 

the catalyst and reduce its effectiveness. Several commercial RHDS technologies are summarized in Table 5. Note that in addition to desulfurization, 

part of the hydrogen 1s consumed through partial conversion of the residuum 

to lighter products such as distillates. 

RHDS technology can reduce the sulfur content of residuum by up to 95 

percent and produce residual oils of 0.3 percent sulfur and below. However, 

in actual operation, several factors influence the economics of RHDS 

processes. These factors include catalyst life, hydrogen consumption, and 

residuum quality. Catalyst life is substantially shortened as metals 

content increases. For example, one pound of catalyst can remove 90 percent 

of the sulfur from roughly 27 barrels of feedstock containing 25 ppm metals; 

to achieve the same sulfur removal from a 100 ppm metals content feedstock, 

4 

only 4.5 barrels can be processed per pound of catalyst. On a relative 

basis, this four-fold Increase 1n metals content causes a six-fold decrease 

in catalyst life. Deactivation of the catalyst can be overcome by 

increasing bed temperature or hydrogen consumption, but results 1n higher 

overall process cost. Because of its lower hydrogen content and higher 

sulfur and metals content, desulfurizing vacuum residuum generally costs 

more than desulfurization of atmospheric residuum. To produce 0.3-1.0 

percent sulfur fuel oils from atmospheric residuum, 345-775 standard cubic 

feet (scf) of hydrogen per barrel of residuum are required, while vacuum 

residuum requires 870-1150 scf to accomplish the same task. In aggregate, 

hydrogen and catalyst costs typically account for 65-75 percent of the total 

cost of RHDS.4 

The approximate cost of RHDS per barrel of product 1s summarized in 

Table 6 for several different crude oils and residual oil product qualities. 

Because of uncertainties in relative inflation rates for various 

desulfurization cost components, these total costs are taken directly from 

4 

the 1979 report in which they appeared and have not been escalated to 1986. 

For a 0.3 percent sulfur product, costs for desulfurization range from 

$3.14-4.53 per barrel. Note that at sulfur levels in the desulfurized 

product of 0.8 percent and above, the cost of desulfurization is roughly 

proportionate to the initial sulfur content of the crude oil. At levels of 
TABLE 5. RESIDUUM HYDRODESULFURIZATION PROCESSES 

Process/Developer Principles of Operation 

Conversion 

(X) 

Maximum Reported 

Sulfur Removal 

IX) Comments 

LC-f1n1ng/ 

Luimnus Crest Inc. 

RCD Unlbon/ 

UOP Inc. 

RDS and VRDS 

hydrotreating/ 

Chevron Research 

Corporation 

Residuum and hydrogen are 50-85 

fed to an expanded bed of 

catalyst. For efficient 

contact, the bed Is 

maintained In turbulence 

by liquid flow. Effluent 1s 

separated at low pressure. 

Feed and hydrogen pass 30-60 

through two fixed beds of 

catalyst in series. First 

bed accomplishes demetallzatlons 

second bed accomplishes 

hydrodesulfurization. 

One pass operation of hydrogen 30-60 

and feed through a fixed bed 

of catalyst. Moderate 

temperature and pressure 

maintained. Graded catalyst 

used to maintain consistent 

quality for different feed 

stocks. 

90 

95 

91 

Product quality Is maintained 

by Intermittent addition and 

withdrawal of catalyst. 

Sulfur content of product fuel 

oil Is nominally IX (by weight), 

which can be blended with cutter 

stocks to produce LSR0. 

Process can treat atmospheric 

or vacuum residuum. Catalyst 

quantity determines amount of 

sulfur removal. 

Process can treat atmosphere 

or vacuum residuum. Thirteen 

units operating, one in design. 

Resldflnlng/ 

Exxon Research 

and Engineering 

Feed and pre-heated hydrogen 

gas are fed to a fixed bed 

of catalyst. Effluent passes 

through separators operating 

at successively lower 

temperatures. Hydrogen gas Is 

recovered and recycled. 

50 N. Av. Process can treat atmosphere or 

vacuum residuum. Two units have 

been Installed. 

Percentage of residuum converted to gas oils and lighter product. 

2 

Sulfur removal numbers are based on the highest removal values presented In the referenced literature. 

Reference: Hydrocarbon Processing. Volume 65. No. 9. September. 1986. pp. 87.90. 
P.12 

TABLE 6. RHDS COST FOR RESIDUAL OIL FROM SELECTED FEEDSTOCKS (1979S/BBL) 

Feedstock 

Cueta 

E. Venezuela 

Kuwait 

Khafji 

Cold Lake 

Sulfur 

(%) 

2.12 

2.38 

3.80 

4.36 

4.55 

Metals 

(ppm) 

292 

274 

60 

118 

236 

Percent Sulfur 

1.6 0.8 

0.91 

1.17 

1.80 

2.20 

2.52 

2.28 

2.45 

2.49 

2.85 

3.42 

in Product 

0.3 

3.91 

3.93 

3.14 

3.60 

4.53 

RO 

0.1 

5.28 

5.71 

3.51 

4.11 

5.84 

Reference 4, p. 110. 

0.3 percent sulfur and below, the Initial metals content 1s dominant in 

determining the cost of desulfurization. 

A number of domestic refineries Installed RHDS capacity during the late 

1970s and early 1980s (Table 7). At that time, crude oils from Algeria, 

Nigeria, and Indonesia (generally containing less than 0.3 percent sulfur) 

were selling at $4-6 per barrel more than crudes from Saudi Arabia, Mexico, 

and Iran (generally containing 1 to 3 percent sulfur). Also during this 

period, residual oils containing less than one percent sulfur wholesaled for 

an average of $5.40 per barrel more than residual oils containing in excess 

c 

of one percent sulfur. Under these conditions, RHDS at $3-5 per barrel 

appeared economically attractive, thus resulting in construction of the 

capacity shown 1n Table 7. 

By September of 1986, however, the differential 1n crude oil prices 

from the above countries had declined to $2-3 per barrel while the price 

differential for residual oils above and below one percent sulfur had 

decreased to roughly $1.50 per barrel. In line with these price changes 

and the above estimates of desulfurization costs, the economic attractiveness of RHDS has significantly declined. Recent telephone contacts with the 

companies listed in Table 7 found that several of the RHDS units have been 

converted to desulfurization of gas oils while others are used solely to 

produce feedstocks for upgrading to lighter products. For example, Phillips 

11 
P.13 

TABLE 7. RESIDUUM HYDRODESULFURIZATION CAPACITY 

Company 

Chevron USA 

Chevron USA 

Exxon, USA 

Phillips 

Phillips 

Valero Refln 

TOTAL 

1ng 

Location 

El Segundo, CA 

Pascagoula, MS 

Baytown, TX 

Borger, TX 

Sweeny, TX 

Corpus Chr1st1, TX 

RHDS Capacity (bpsd)a 

24,000 

96,000 

71,000 

50,000 

75,000 

54,000 

370,000 

a barrels per stream day (barrels per day when operating at full capacity). 

Reference 12, pp. 100-115. 

Petroleum Company's Borger, Texas and Sweeny, Texas refineries have the 

capacity to desulfurize 50,000 bpd and 75,000 bpd of residuum, respectively; 

however, all of the desulfurized product 1s sent to a catalytic cracker for 

fractionation to lighter products. ' Exxon has converted Its 71,000 bpd 

o 

RHDS unit in Baytown, Texas, to desulfurization of gas oils. Similarly, 

Chevron's El Segundo, California refinery has converted most of Its 

desulfurization capacity to desulfurization of gas oil for production of 

9 low-sulfur diesel fuels. Chevron does produce and market low-sulfur 

residual oils of 0.25-0.5 percent sulfur at four of Its refineries, but uses 

disti11 at 

than RHDS 

AVAILABILITY OF VLSRO 

, Supplies of VLSRO and RHDS capacity in 1985 based on the point of 

refining are shown in Table 8; foreign countries are listed in descending 

order of import volumes. Of the total domestic VLSRO supply, 76 percent was 

imported. Of the remaining 24 percent produced in the U.S., 42 percent was 

12 

g 

low-sulfur diesel fuels. Chevron does produce and market low-sulfur 

residual oils of 0.25-0.5 percent sulfur at four of Its refineries, bi 

distillation of low-sulfur oils (primarily from Indonesia and Africa) rather 

1 
P.14 

TABLE 8. U.S. SUPPLY OF VERY LOW SULFUR RESIDUAL OIL 

BY LOCATION OF REFINING AND RHDS CAPACITY, 1985 

REFINING LOCATION 

( 

DOMESTIC 

PADDC I (East Coast) 

PADD II (Midwest) 

PADD III (Gulf Coast) 

PADD IV (Rocky Mountains) 

PADD V (West Coast) 

Subtotal 

IMPORTED 

Algeria 

Virgin Islands 

Brazil 

Nigeria 

Netherlands Antilles 

Venezuela 

Canada 

Bahamas 

Mexico d 

Western Europe 

-Other OPEC 

Other Western Hemisphere 

Other Eastern Hemisphere 

Subtotal 

TOTAL 

BREAKOUT BASED ON RHDS CAPACITY 

Domestic with RHDS Capacity 

Imports with RHDS Capacity 

Domestic without RHDS Capacity 

Imports without RHDS Capacity 

VOLUMEa 

Thousand Barrels) 

1,487 

2,727 

8,848 

1,202 

10,523 

24,787 

19,794 

10,529 

4,961 

4,145 

4,140 

3,989 

3,540 

3,224 

2,822 

2,500 

1,302 

6,775 

10,480 

78,201 

102,988 

19,371 

23,380 

5,416 

54,821 

RHDS CAPACITY6 

(bpsd) 

0 

0 

346,000 

0 

24,000 

370,000 

0 

130,000 

0 

0 

0 

200,400 

3,600 

0 

5,000 

52,000 

0 

0 

0 

391,000 

•*•••« • 

761,000 

370,000 

391,000 

0 

0 

a 

b 

c 

d 

Reference 2, pp. 55-56. 

Reference 3, Appendix C. 

Petroleum Administration for Defense District, geographic divisions of 

U.S. used by DOE for petroleum accounting purposes. 

United Kingdom, Spain, Norway, Netherlands. 

13 
P.15 

produced on the West Coast (PADD V) and 36 percent in the Gulf Coast states 

(PADD III). Both of these PADDs have significant RHDS capacity; but as 

discussed above, much of this capacity has been converted to processing 

lighter products. 

Of the foreign supply, 70 percent come from countries that do not have 

any RHDS capacity and thus base production on refining of low-sulfur crude 

oils. Of the remaining 30 percent, only the Virgin Islands, Venezuela, and 

western Europe have significant RHDS capacity. Because of the relatively 

high (2-3 percent) sulfur content of Venezuelan atmospheric residuum, 1t 1s 

likely that removal of sulfur by RHDS approaches 90 percent. Data on the 

sulfur contents of crude oils processed in the Virgin Islands and western 

Europe was not found. 

Thus, although precise quantitative data are not available detailing 

the method by which domestic VLSRO supplies are currently produced, 

available data on both the geographic distribution and economics of VLSRO 

refining suggest that the majority of current supply comes from distillation 

of yery low-sulfur crude oils. RHDS may be Involved In the production of 

roughly 20 percent of the total domestic supply of VLSRO, but the percentage 

of sulfur removal during RHDS 1s uncertain. 

14 
REFERENCES 

1. Beyaert, Bruce, Chevron USA, San Francisco, California, telephone 

conversation with Ed Moretti, Radian Corporation, January 14, 1987. 

2. Energy Information Administration, Petroleum Supply Annual 1985. 

Washington, DC, DOE/EIA-0340(85)/1, May 22, 1986. 

3. National Petroleum Council, U.S. Petroleum Refining. October 1986, 

pp. 26-36, Appendix C. 

4. Comley, E.A., Keen, R.T., and Tyndall, M.F., (Catalytic Inc.), 

Technology Assessment Report for Industrial Boiler ADDHcations: Oil 

Cleaning. U.S. EPA, Research Triangle Park, NC, EPA-600/7-79-178b, 

November 1979. 

5. Energy Information Administration, Monthly Energy Review. Washington, 

DC, D0E/EIA-0035(86/9), September 1986. 

6. Davis, Ed, Phillips Petroleum Co., Borger, Texas, telephone 

conversation with Ed Moretti, Radian Corporation, January 6, 1987. 

7. Earnest, Neil, Phillips Petroleum Co., Sweeny, Texas, telephone 

conversation with Ed Moretti, Radian Corporation, January 6, 1987. 

8. Reid, Frank, Exxon Corporation, Baytown, Texas, telephone conversation 

with Ed Moretti, Radian Corporation, January 6, 1987. 

9. Bredehofte, Ron, Chevron Corporation, El Segundo, California, telephone 

conversation with Ed Moretti, Radian Corporation, January 12, 1987. 

10. Houde, Ed, UOP Inc., telephone conversation with Ed Moretti, Radian 

Corporation, January 6, 1987. 

11. van Driesen, Roger, Lummus-Crest Inc., telephone conversation with Ed 

Moretti, Radian Corporation, January 6, 1987. 

12. Oil and Gas Journal. Vol. 84, No. 12, March 24, 1986, pp. 100-115. 

13. Whittington, Lou, M.W. Kellogg Co., telephone conversation with Ed 

Moretti, Radian Corporation, January 5, 1987. 

14. Bruch, Herbert W., National Petroleum Refiners Association* telephone 

conversation with Ed Moretti, Radian Corporation, December 3, 1986. 

15