Naphtha syncrude

Gaseous C3-C4 olefins, which constituted one-third of the syncrude, were oligomerized to liquid products, mainly in the naphtha boiling range, to boost motor gasoline production. 

The Fe-HTFT syncrude is fractionated in an atmospheric distillation unit to produce mainly naphtha and distillate, with a small amount of residue that is used as fuel oil (not shown in Figure 18.7). No vacuum distillation unit has been included in the design, since it would be superfluous with the limited residue production. The natural gas liquids are fractionated separately. 

Tar Sands Canadian tar sands either are strip-mined and extracted with hot water or employ steam-assisted gravity drainage (SAGD) for in situ recovery of heavy oil (bitumen). The bitumen is processed into naphtha, kerosine, and gasoline fractions (which are hydrotreated), in addition to gas (which is recovered). Current production of syncrude from Canadian tar sands is about 113,000 T/d (790,000 B/d) with expected increases to about 190,000 T/d (1.7 MB/d) by 2010. 

We will examine three synthetic fuel scenarios and compare their implications regarding sulfur availability with the current and projected market for sulfur to the year 2000. The analysis will consider three production levels of synthetic fuels from coal and oil shale. A low sulfur Western coal will be utilized as a feedstock for indirect liquefaction producing both synthetic natural gas and refined liquid fuels. A high sulfur Eastern coal will be converted to naphtha and syncrude via the H-Coal direct liquefaction process. Standard retorting of a Colorado shale, followed by refining of the crude shale oil, will round out the analysis. Insights will be developed from the displacement of imported oil by synthetic liquid fuels from coal and shale. 

The plant will process 27,836 TPSD of Illinois No. 6 high sulfur bituminous coal containing 4.45 wt% sulfur on an as recieved basis. The output of fuel products form the plant is 15,531 BPSD of naphtha and 51,325 BPSD of syncrude. 1,178 tons per day of elemental sulfur is produced. This represents 95 wt% of the total input sulfur in the feedstock coal. Most of the remaining sulfur is still present in the liquid synthetic crude oil. From the available data for this proposed plant, the output of elemental sulfur is calculated to be 0.0176 tons per product barrel. Since a high sulfur coal was used this represents a high sulfur production case as it is likely that direct liquefaction facilities will use high sulfur Eastern bituminous coals as feedstock. 

Hydrocarbon-type Characterization. Table I lists the four fractions, their wt % of the syncrude, and their hydrocarbon-type compositions. The values for polar material for the two naphthas and the light oil are estimates based on their nitrogen contents. The polar material value for the heavy oil is based on the recovered weights from the Florisil separa-... 

The first fraction listed is the 550°F-f- heavy oil produced by hydrogenation of the 550°-850°F heavy oil from distillation and coking of the in situ crude oil. This is the same fraction listed in Tables I and II as the syncrude heavy oil fraction. The second fraction listed in Table VII is the 350°-550°F light oil produced in the foregoing hydrogenation, and the third fraction is the 175°-350°F heavy naphtha produced in the same hydrogenation. 

The synthetic crude was produced by hydrogenating the IBP-350°F naphtha, the 350°-550°F light oil, and the 550°-850°F heavy oil fractions obtained from in situ crude shale oil by distillation followed by coking of the 850°F-f- residuum. Characterization of the syncrude was accomplished by examining the following fractions CB-175°F light naphtha, 175°-350°F heavy naphtha, 350°-550°F light oil, and 550°-850°F heavy oil. 

The light naphtha comprised 3% of the syncrude and contained 72% paraffins, 20% naphthenes, 8% aromatics, and less than 0.5 ppm nitrogen. The heavy naphtha comprised 21% of the syncrude and contained 43% paraffins, 43% naphthenes, 14% aromatics, and less than 1 ppm nitrogen. The light oil comprised 49% of the syncrude and contained 51% paraffins, 25% naphthenes, 24% aromatics, and 79 ppm nitrogen. The heavy oil comprised 27% of the syncrude and contained 73% saturates, 6% olefins, 19% aromatics, 2% polar compounds, and 935 ppm nitrogen. 

V (Ni-Mo) and the lowest yields with catalysts III (Ni-W) and IV (Ni-W). The highest conversion, i.e., material converted to products boiling below 550°F, was attained with catalyst VI (Ni-Co-Mo). The lowest conversion was attained with catalyst IV (Ni-W), a hydrocracking catalyst. The highest yields of naphtha and light oil were attained with catalysts I (Co-Mo) and VI (Ni-Co-Mo). Because of its high sustained denitrification activity, catalyst V (Ni-Mo) was selected for use in the preparation of syncrude by hydrogenation of the in situ distillate fractions. 

In Table X the properties of the syncrude prepared from in situ crude shale oil are compared with the properties of a syncrude listed by the NPC. Relative amounts and properties of the naphthas, light oils, and heavy oils are also compared. These data show that the nitrogen content, sulfur content, pour point, viscosity, and API gravity of syncrude prepared from in situ crude shale oil are lower than those suggested in... 

Hydrogenation tests made on the 600°-1000°F heavy gas oil from in situ crude shale oil showed that a nickel-molybdenum-on-ahimina catalyst was superior to either cobalt-molybdenum-on-alumina or nickel-tungsten-on-alumina catalysts for removing nitrpgen from shale oil fractions. This nickel-molybdenum-on-alumina catalyst was used in the preparation of the synthetic crude oil. A high yield of premium refinery feedstock whose properties compared favorably with those of a syncrude described by the NPC was attained by hydrogenating the naphtha, light... 

H-Coal naphthas and distillates derived from Illinois No. 6 (Burning Star Mine) and Wyodak coals were supplied by Hydrocarbon Research, Inc. The naphthas and distillates were blended in the appropriate proportions to obtain a whole syncrude derived from each coal. Properties of these syncrudes are shown in Table I. For comparison, Table I also shows properties of the SRC-II syncrude used in the study described in the previous chapter. The SRC-II syncrude was derived from a West Virginia coal (Pittsburgh Seam, Blacksville No. 2 Mine of the consolidated Coal Company). The H-Coal and SRC-II syncrudes are not directly comparable because the coals used to derive these syncrudes differ. 

Properties of the naphthas produced from the syncrudes in the above tests are shown in Table V. Dinaphthenes are found in the 300-350°F naphtha and, surprisingly, in the 250-300°F naphtha. High levels of these compounds can make coal-derived naphthas difficult to reform. ( 9) A combination gas chromato-graphic-mass spectrometric (GC-MS) analysis of the 250-300°F naphtha from hydrotreated Illinois H-Coal found that the dinaphthenes are 8-carbon atom compounds (1.8% octahydropenta-lene) and 9-carbon atom compounds (0.7% bicyclo 3.3.1 nonane, 0.4% methyloctahydropentalene, 1.0% octahydroindenes, and 2.6% unidentified compounds) These dinaphthenes should not yield naphthalene when reformed. If the initial point of the jet fuel is 300°F or less, the 300°F " naphtha should be easy to reform. 

PROPERTIES OF NAPHTHAS FROM SEVERELY HYDROTREATING ILLINOIS H-COAL, WYODAK H-COAL, AND SRC-II SYNCRUDES ... 

In Table II, the boiling ranges of petroleum and the two major syncrudes are shown. The very high naphtha yield and the absence of residue in coal derived syncrudes are significant. 

Also, it should be noted that shale oil is predominently in the middle distillate boiling range with low residue and naphtha content. The absence of resid in coal liquids results from the severe hydrogenation conditions imposed in the coal liquefaction processes and the use of the remaining residue for hydrogen production. For shale oil, the retorting process destroys most the residual materials leaving a syncrude that is mainly a distillate. 

The plan calls for processing Illinois No. 6 or comparable bituminous coal in both the synthetic crude and fuel oil modes and then a subbituminous coal in the syncrude mode only. Each run is expected to be about three months in length to allow ample time for lineout and collection of engineering and operating data. Yields in the syncrude mode will show a high percentage of naphtha and light gas oil while in the fuel oil mode there will be over 80 percent of 400 plus distillate and residuum. 

Once the synthetic crude oils from coal and oil shale have been upgraded and the heavy ends converted to lighter distillates, further refining by existing processes need not be covered in detail except to note the essential character of the products. The paraffinic syncrude from oil shale yields middle distillates which are excellent jet and diesel fuel stocks. The principal requirements are removal of nitrogen to the extent necessary for good thermal stability of the fuels and adjustment of cut points to meet required pour or freeze points, limited by the presence of waxy straight-chain paraffins. The heavy naphtha from shale oil can be further hydrotreated and catalytically reformed to acceptable octane number, but with considerable loss of volume because of the only moderate content of cyclic hydrocarbons, typically 45-50%. On the other... 

The raw oil obtained is first fractionated by distillation producing naphtha, light oil, heavy oil, and residues. The residues are then cracked to gas, naphtha, light oil, and heavy oil. A final hydrogenation is then made to produce a synthetic petroleum (syncrude). 

The unit recycles up to 40,000 metric tons per year of mixed plastic containing up to 10% PVC. Up to 20% of its feed will be mUled plastic particles less than 8 mm in diameter. [The] unit operates at 150-300 bars and about 470°C in a hydrogen atmosphere, producing a syncrude containing 60% paraffins, 30% naphtha, 9% aromatics and 1% olefins. Chlorine... is converted to HCl in the reactor, then neutralized with calcium carbonate. 

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