Industrial Steam Cracker Process

The world petrochemical industry is surveyed annually in the Oil Gas Journal as the Ethylene Report. This is a useful source of country production, individual steam crackers (including ownership) and the feedstock used. Since 2006 US olefins and the US natural gas liquid supply and prices are each reviewed twice per year by Lippe. Weissermel and Arpe have provided an excellent description of many technologies and approaches to chemical synthesis in the chemical process industry. 

The number of streams feeding the plant, the number of contaminated streams, the mercury concentration and the type of mercury removal system considered aU have a potential impact on the cost of the removal system. For overall economic assessment, one should consider the in-plant impact and the cost of removal systems for regeneration/waste effluent systems as well as down-stream client impacts. One should also consider other contaminants which are present in the natural gas condensate i.e. mainly arsenic but also sometimes phosphorus, lead or sihcon. For these contaminants, there is no removal process which is industrially apphed on the steam-cracker effluents. 

Finally, it is important to address the topic that is not only scary, but keeps many industrial chemists awake at night cost (see Figure 2.4). The highly optimized production processes for polyolefins, combined with the low costs of the raw materials, lead to bulk prices as low as 1 per kilogram, and sometimes even lower. This, in turn, leads to the realization that almost any other chemistry is more expensive than that produced from steam cracker products there is no room for anything else - the low-hanging fruits are gone ... 

Propylene is also a product of the steam-cracking process (up to 15 wt% of the steam cracker product mix. Section 6.6). In addition, it is obtained by catalytic dehydrogenation of propane (Section 5.3.1) and as a by-product of the FCC process (Section 6.7.2). The technical relevance of propylene as a feedstock for the synthesis of industrial chemical processes has ever increased since the 1960s. The increasing value of propylene can be realized from the fact that propylene was seen in former times as an undesirable by-product of the steam-cracking process and as such it was... 

Until 1945, most developments in the petrochemical industry arose in the United States, where refinery processes were advanced and feedstocks were readily available. There were no similar refineries in Europe and chemical production was still firmly based on coal. Petrochemicals could not be produced in Europe until the late 1950s, when the first large refineries were birilt and cheap rraphtha was used in steam crackers and for ammonia production. Estimates of petrochemical production in both the United States and Europe from 1935 to 1965 demonstrate the difference as shown in Table 7.1. 

More than 90% of today s petrochemicals are produced from refineiy products. Most are based on the use of C2-C4 olefins and aromatics finm hydrocarbon steam cracking units, which are even more closely linked to refineries. In North America, the feedstock for steam cracker units have generally been ethane, propane, or LPG. As a result, most of the propylene and aromatics have been provided by FCC units and catalytic reformers. In maity other parts of the world where naphtha feed has been more readily available, suppUes of propylene and aromatics have been produced directly by steam cracking. When necessary, the catalytic dehydrogenation of paraffins or dealkylation of toluene can balance the supply of olefins or benzene. In Table 7.2 some of the catalytic processes that convert olefins and benzene from a steam cracker into basic petrochemicals for the modem chemical industry are shown. 

Reaction of steam with carbon is one of the basic processes involved in the gasification of coals or chars to produce clean fuels. The industrial importance of this reaction is considerable, particularly at this time of spiraling energy costs. In addition, the steam-carbon reaction finds other important industrial applications, such as preventing or minimizing the coking of olefin-plant cracker-tubes. Because of its commercial importance, the steam-carbon reaction has been studied extensively, and excellent reviews are available (1,2). In addition to reaction kinetics and mechanisms, the effects of carbon structure, catalysis by metals, and impurities (anions) have been investigated (3,4, .5) ... 

---