Product slate

Properties. Shell s two-step SMDS technology allows for process dexibiUty and varied product slates. The Hquid product obtained consists of naphtha, kerosene, and gas oil in ratios from 15 25 60 to 25 50 25, depending on process conditions. Of particular note are the high quaHty gas oil and kerosene. Table 2 gives SMDS product quaHties for these fractions. 

Refinery Production. Refinery propylene is formed as a by-product of fluid catalytic cracking of gas oils and, to a far lesser extent, of thermal processes, eg, coking. The total amount of propylene produced depends on the mix of these processes and the specific refinery product slate. For example, in the United States, refiners have maximized gasoline production. This results in a higher level of propylene production than in Europe, where proportionally more heating oil is produced. 

Steam Cracking. Steam cracking is a nonselective process that produces many products from a variety of feedstocks by free-radical reactions. An excellent treatise on the fundamentals of manufacturing ethylene has been given (44). Eeedstocks range from ethane on the light end to heavy vacuum gas oil on the heavy end. All produce the same product slate but in different amounts depending on the feedstock. 

Separation and Purification of Isomers. 1-Butene and isobutylene caimot be economically separated into pure components by conventional distHlation because they are close boiling isomers (see Table 1 and Eig. 1). 2-Butene can be separated from the other two isomers by simple distHlation. There are four types of separation methods avaHable (/) selective removal of isobutylene by polymeriza tion and separation of 1-butene (2) use of addition reactions with alcohol, acids, or water to selectively produce pure isobutylene and 1-butene (3) selective extraction of isobutylene with a Hquid solvent, usuaHy an acid and (4) physical separation of isobutylene from 1-butene by absorbents. The first two methods take advantage of the reactivity of isobutylene. Eor example, isobutylene reacts about 1000 times faster than 1-butene. Some 1-butene also reacts and gets separated with isobutylene, but recovery of high purity is possible. The choice of a particular method depends on the product slate requirements of the manufacturer. In any case, 2-butene is first separated from the other two isomers by simple distHlation. 

The H-Coal process could operate in one of two modes, depending on the desired product slate. In the "syn-cmde" mode, a fluid-bed coking unit was employed to maximize recovery of distillate from the Hquefaction product (Fig. 7a). When operated in the fuel oil mode (Fig. 7b), no coker was used and the primary product was a coal-derived low sulfur fuel oil. Total hydrogen demand on the process was also reduced in the latter mode of operation. 

Development of SASOL. Over 70% of South Africa s needs for transportation fuels are being suppHed by iadirect Hquefaction of coal. The medium pressure Fischer-Tropsch process was put iato operation at Sasolburgh, South Africa ia 1955 (47). An overall flow schematic for SASOL I is shown ia Figure 12. The product slate from this faciUty is amazingly complex. Materials ranging from hydrocarbons through oxygenates, alcohols, and acids are all produced. 

Products from hydrocracking processes lack olefinic hydrocarbons. The product slate ranges from light hydrocarbon gases to gasolines to residues. Depending on the operation variables, the process could... 

One of the unique issues in the development of advanced-performance materials is that they are very product-specific, and their development requires expensive prototype iteration and performance testing. The product development is people- and design-intensive and usually results in a niche market for the material that is, the specific product slate for which the material has been designed and tested. Many of the applications are in high-tech industrial products like aerospace components, so the total volume of material used will be small. Thus, attractive commercialization schemes require that the material have intrinsic value that will justify a high margin, or there must be a product application for which the value can be captured in the end product. 

A considerable effort has been emended in the past few years by many researchers in attempts to better understand the mechanism by which coal is liquefied. From this work has emerged the concept of short residence time coal liquefaction which promises potential process advantages, small reactor, minimum hydrogen flow, and the efficient utilization of hydrogen for a particular product slate. 

Change in Fischer-Tropsch synthesis. In the 1990s the Kellogg Fe-HTFT synthesis section was decommissioned and additional Fe-LTFT synthesis capacity was added with the introduction of a slurry bed reactor.35 This modified the syncrude feed to the refinery to Fe-LTFT only. This was accompanied by a significant change in the product slate being produced. 

The selection of Co-LTFT synthesis, the associated refinery design, and the product slate for Oryx GTL all mimicked the SMDS process. Likewise, no provision has been made for the upgrading of short-chain olefins or oxygenates. 

The selection of crude oil type is critical to the design and economic success of a crude oil refinery. Different crude oil types require a different refining strategy, and depending on the crude oil type, it may be easier or more difficult to achieve a specific product slate. The product slate is often determined by regional markets, unless the products are specifically earmarked for export. This also holds true for Fischer-Tropsch syncrude. 

Selecting HTFT or LTFT syncrude to match the desired product slate is important for achieving an efficient design. HTFT syncrude is more... 

Table 4.1 Biomass Pyrolysis Product Slate As A Function of Heating Rate, Residence Time, and Temperature...

Pyrolysis processes can be divided into two groups low temperature and high temperature. The products of pyrolysis processes differ and can be controlled by temperature and the rate of material heating. Table 4.1 provides a summary of variations of the product slate for biomass and coal feedstocks. 

In the chapter on olefms plants, in the section on propylene, a route to making propylene involved butene-2. In this process, called metathesis, ethylene and butene-1 are passed over a catalyst, and the atoms do a musical chair routine. When the music stops, the result is propylene. The conversion of ethylene to propylene is an attraction when the growth rate of ethylene demand is not keeping up with propylene. Then the olefins plants produce an unbalanced product slate, and producers wish they had an on-purpose propylene scheme instead of just a coproduct process. The ethylene/butene-2 metathesis process is attractive as long as the supply of butylenes holds out. Refineries are big consumers of these olefins in their alkylation plants, and so metathesis process has, in effect, to buy butylene stream away from the gasoline blending pool. 

In a typical fluid catalytic cracker, catalyst particles are continuously circulated from one portion of the operation to another. Figure 9 shows a schematic flow diagram of a typical unit W. Hot gas oil feed (500 -700°F) is mixed with 1250 F catalyst at the base of the riser in which the oil and catalyst residence times (from a few seconds to 1 min.) and the ratio of catalyst to the amount of oil is controlled to obtain the desired level of conversion for the product slate demand. The products are then removed from the separator while the catalyst drops back into the stripper. In the stripper adsorbed liquid hydrocarbons are steam stripped from the catalyst particles before the catalyst particles are transferred to the regenerator. 

Finally, the product slate (e.g. olefin production, petrochemical feedstock production), or the product quality (e.g. gasoline octane improvement) may dictate a reduction in rare earth usage. 

Table I presents a refinery sulfur recovery capacity forecast made by the National Petroleum Council (NPC). The top portion of the table represents the initial conditions based on current crude input and refinery product slates the bottom indicates additional capacity required for each of three, non-additive, scenarios. As the NPC study shows that sulfur production, as a percent of capacity, in 1982 is expected to be 60% in district I, 54% in district II, 71% in district III, 72% in district IV, and 49% in district V...

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