5 Hydrogen in Oil Refinery Operations
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HAMPTON G. CORNEIL and FRED J. HEINZELMANN Exxon Enterprises Inc., P.O. Box 192, Florham Park, NJ 07932
A study (Reference 1) completed in April, 1977, was conducted by Exxon Research and Engineering Company for the Conservation Division, Department of Energy, to predict the quantities of industrial hydrogen that will be needed in the U. S. during the 1980-2000 period for the current industrial uses and to determine the costs
of producing these industrial hydrogen products by several alternative processes that are likely to be used commercially or considered for commercial use during this period. The data concerning crude runs to stills and hydrogen processing have been updated in this study to reflect current estimates of these values. Hydrogen for use in petroleum refining operations provides a major hydrogen requirement today
and this will continue throughout the 1980-2000 period. This paper discusses the uses of hydrogen in petroleum refining, the quantities of hydrogen that will be
required during the 1980-2000 period, and the economics
of producing this hydrogen. As is explained in Reference 1, investment and operating cost data for various hydrogen manufacturing processes were provided for this study by Chem Systems, Inc., New York, New York. These economics data were developed using identical methods and assumptions, thereby permitting side-by-side comparisons of the several processes. Conclusions
Hydrogen willfully produced for use in U. S. refineries for gas oil desulfurization and residuum hydrocracking and desulfurization probably will increase from about 1.8 billion SCF/D in 1980 to 3.9 billion SCF/D in the year 2000. These figures 0-8412-0522-l/80/47-116-067$07.00 © 1980 American Chemical Society In Hydrogen: Production and Marketing; Smith, W., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1980.
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exclude refinery by-product hydrogen (from octane improvement reformers) which is used for desulfurizing various light distillate products. Steam reforming using natural gas and other light hydrocarbon feed stocks will continue to be the most
attractive method of manufacturing willfully-produced refinery hydrogen. Feed stocks required for reforming in U. S. refineries will increase from about 150,000
B/D crude oil equivalent in 1980 to 330,000 B/D in the
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year 2000. Partial oxidation of resid feed stocks is used for
producing 5% to 7% of current willfully produced hydrogen. Its use will not increase significantly because manufacturing costs are, in general, higher than with steam reforming. Coal gasification probably will not be used to manufacture refinery hydrogen in the U. S. to any significant extent during the 1980-2000 period. Capital investments and operating costs for coal gasification in the four major refining centers are likely to be much higher for coal gasification than for steam reforming. Hydrogen Uses in Petroleum Refining Prior to the 1965-1970 period, most of the hydrogen used in petroleum refining was used for treating light naphthas and middle distillates to provide for desulfurization and product stability. These hydrogen-treating operations require little hydrogen, ranging from 10-20 SCF/B for the light naphthas to 100-200 SCF/B for the middle distillates. Stringent environmental restrictions requiring lower sulfur content products have accelerated the use of these hydrogen-processing operations. Hydrogen for these operations has in the past and will continue to be provided as by-product hydrogen produced in naphtha reformers operated to increase the octane number of motor gasoline fractions. Although this by-product hydrogen is typically of only 70% to 80% hydrogen content, this low-purity hydrogen is satisfactory for hydrogen-treating these light distillates. In recent years, a more severe type of hydrogen treating has been added to refinery processing systems in which heavy distillates (gas oil) and residuum are hydrotreated to remove sulfur and to convert these heavier hydrocarbons to products of lower molecular weight. The addition of "external" hydrogen increases the H/C ratio of the products substantially above that of the feed stocks. The use of these hydrocracking and
In Hydrogen: Production and Marketing; Smith, W., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1980.
5. coRNEiL and HEiNZELMANN
Hydrogen in Oil Refinery Operations
69
hydrodesulfurization processes has become increasingly important as crude oil supplies have become heavier (of
lower H/C ratio) and of higher sulfur content and
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because of the economic need to convert residuum to
distillate products. The conversion of residuum to lighter products can also be conducted with thermal cracking (vis breaking) or coking, a process that removes carbon from the system, thereby increasing the H/C ratio of the coker products relative to that of the feed stock. Figure 1 is a simplified flow diagram of refinery processing. In this system, conversion of resid (650°F +) is provided by either hydrotreating or coking. Figure 2 shows the system assuming hydrotreating is used for resid conversion. The processing sequence shown in Figure 3 assumes coking is used for residuum conversion. The choice between these two alternative residuum-
processing methods depends on many economic factors, and how such a choice would be made is beyond the scope of this study. However, these two processes are compared in Reference 2. Figure 4, a summary chart from Reference 2, indicates that coking is the preferred choice if it is desired to convert 60% or more of the crude (Arabian Heavy, in this case) to prime (clean) products. When hydrogen is used for hydrodesulfurizing and hydrocracking of gas oil (heavy distillates) and residuum, large quantities of high-purity hydrogen (95%+) are required as inputs to these plants, and the by-product hydrogen from octane improvement reformers is not adequate. Hydrogen consumption for these processes range from 300 SCF/B for light gas oil desulfurization to 3000 SCF/B for severe hydrocracking. Since this hydrogen requirement is substantial and by-product hydrogen from other operations is not adequate, these gas oil desulfurizers and resid hydrocrackers are installed with their own hydrogengenerating facilities . Hydrogen Requirements for Petroleum Refining The principal current U. S. requirements for industrial hydrogen are for use in petroleum refining,
for the manufacture of ammonia and methanol, and for a
wide variety of small uses including chemicals manufacture, metallurgy, welding, etc. It is beyond the scope of this paper to discuss the factors that will affect the future requirements for ammonia, methanol, and small-user hydrogen; however, these factors are discussed rather completely in Reference 1.
In Hydrogen: Production and Marketing; Smith, W., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1980.
70
HYDROGEN: PRODUCTION AND MARKETING
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