The key data supporting Hart's pessi mism are the Federal Power Commis sion's reserve-to-production ratios for natural gas. In 1972 the ratio was 10:1. In 1975 it was 9:1, and in 1976 Hart expects it to decline to 8.5:1. This decline simply means that the availability of gas is not increasing, and the cause is placed by Hart squarely on the shoulders of Con gress and its failure to deregulate natural gas prices. At best Hart sees conservation of en ergy reducing gas demand 20% in the years ahead. But that merely subdues symptoms of a national energy disease; it does not treat the disease itself. "Whether the gas price is pegged at $1.42 or $14.20 [per 1000 cu ft], it is the wrong price if it is determined by government fiat," Hart says. The only way to ensure sufficient gas supplies in the future is to allow the market place to determine prices and availability. Hart, reflecting the sentiment of the gas companies, calls for selling gas on the basis of its legitimate market value rather than on its age. But despite the gloomy picture painted by Hart, there are some bright spots. One of them is the liquefied natural gas pro gram, in which there are only a few tech nical problems and very few environ mental ones. It came as a shock to the in dustry when the Ford Administration's energy message appeared to place a ceil ing of 1 trillion cu ft per year on imported LNG. The subsequent "clarification" raised the ceiling to 2 trillion cu ft, but even this is viewed as unrealistic and in adequate by the gas industry. Hart also says that low import ceilings on LNG could impede further development of the
far are in good conformity with what was expected," Barre says. The comparatively high ethylene yield stems from several unique aspects of the hydropyrolysis operation, Barre notes. The severe cracking intensity results from the high temperature (between 800 and 900 °C) and high pressure (10 to 30 atm) employed. And the extremely short resi dence time of the reactants in the cracker reduces the likelihood of secondary reac tions occurring, thereby ensuring that large quantities of olefins are obtained. "Hydrogen participates in the initiation of cracking," Barre explains. In addition, it opposes formation of heavy products and greatly reduces the tendency to cok ing by stabilizing the unsaturated prod ucts. Moreover, it makes up for any lack of hydrogen in the charge, permitting use of feedstocks such as heavy petroleum cuts, various olefin fractions, and the like, that have a low hydrogen-to-carbon ratio. No less important, he adds, is the highly exothermic nature of the reaction and the ability to control conditions to achieve very high cracking temperatures. Using naphtha feedstock, and opti mizing for ethylene production, it's pos sible to obtain ethylene yields of 45%, Barre claims. This is accomplished by recycling propylene and steam-cracking the ethane by-product. On the other hand, if coproduct propylene is needed for downstream use, it's possible to obtain up to 35% ethylene and 18% propylene by recycling other by-products of the crack ing reaction. "From gas oil, we can get a 35% yield of ethylene, 25 to 30% methane, and less than 13% heavy fuel," Barre adds. "This is a definite advantage of hydro pyrolysis." The high yield of associated methane, rather than being a drawback, can be turned to advantage in the process, Barre time in the cracking unit is less than 0.1 explains. For instance, it can be used as second. And the size of an installation fuel to heat the cracking furnace, and it is would be smaller than that of a conven a source of additional hydrogen needed in tional steam cracker producing the same the process. Alternatively, the methane quantity of ethylene, thus providing for could be used to make ammonia in an other unit. "In this case, it would be ad substantial capital investment savings. After several years of basic studies at visable to save part of the methane for CECA, two other French companies, hydrogen production and use the heavy Heurty and Naphtachimie, have joined by-products for heating the cracker." CECA in pilot-scale testing of the process. He foresees three likely uses of hydro Heurty built a 1000 metric-ton-per-year pyrolysis. One is in "a simplified and (of ethylene) unit at Naphtachimie's economical unit" for making ethylene in complex in Lavera, near Marseille. The yields of almost 50%. "The investment plant started up this summer. "Results so and energy consumption would be sub stantially lower than for a steam cracker Barre: 50 % ethylene yields of the same production," he believes. An ο alternate hydropyrolysis unit would be ο -C similar to a steam cracker of 400,000 Ω. metric-tons-per-year ethylene (output iS Ζ capacity) starting from naphtha or gas oil, LU οβ maximizing the ethylene and light olefins υ production, and minimizing the heavy fuel yield. Even more interesting, in Barre's view, would be an add-on hydropyrolysis unit for an existing large steam cracker. This arrangement would draw on the steam cracker's by-products, such as butenes and cracked gasoline combined with me dium or heavy cuts of distilled crude oil, to increase overall ethylene recovery. •
gas industry in this country and possibly adversely affect some export projects as well. Another bright spot is the promising coal conversion industry, which, Hart observes, is currently stalled by the lack of suitable incentives, such as construc tion loan guarantees. Pending loan guar antees and price deregulation, there is no way, in Hart's view, to achieve rates that reflect full cost of service, which the public eventually will have to pay one way or another. The pros and cons of coal gasification also were touched on in the keynote ad dress of Dr. Henry R. Linden, president of the Institute of Gas Technology. About 80% of the nation's fossil fuel reserves are coal. At the present consumption projec tion, assuming continued growth from 2 to 3% per year, these reserves are expected to last about 100 years, but they will cost a great deal of money. Linden estimates the cost of high-Btu gas from coal at from $2.50 to $3.50 per million Btu, using sec ond-generation conversion technology now being readied for commercial use. The cost is even higher for first-genera tion technology, now being used in some foreign countries. The prices estimated by Linden are roughly equivalent to an oil price of $15 to $20 per bbl but are ex pected to escalate drastically in the next 25 years. Neither Linden nor Hart are optimistic about the immediate post-election future with respect to the gas industry. However, both hope that the industry eventually will achieve the monetary incentives that they regard as realistic and reason able. •
Naphtha cracking: new high-yield process Naphtha is the primary source of ethylene outside the U.S. But there are several commercial and technical drawbacks as sociated with naphtha cracking: For one, naphtha prices can run high, a reflection of its tight availability; for another, eth ylene yields are less than 30%. However, an unusual cracking tech nology involving use of hydrogen is in the offing. It is expected to overcome the problems associated with conventional naphtha cracking while providing at tractive additional advantages. Details of the development were disclosed for the first time last month by Claude Barre of Paris-based CECA S.A., the chemical arm of Pierrefitte-Auby. The occasion was the World Congress of the Societe de Chimie Industrielle, held in Valley Forge, Pa. Called hydropyrolysis, the technique can be used with naphtha or with lessexpensive gas oil. Ethylene yields ap proaching 50% are possible by recycling coproducts to the cracker. And methane, which also is produced, provides the op tion of making ammonia in an associated operation. Barre cites other advantages. Hydro pyrolysis, a term coined by CECA, does not require a catalyst. The cracking op eration itself is exothermic. Residence 18
C&EN Nov. 1, 1976
