Naphtha utilization

Heavy straight-run gasoline or naphtha Utilized primarily as catalytic reformer feedstock... 

The sulfur-compound containing natural gas and naphtha utilized in the steam-reforming process, have therefore to undergo prior desulfurization. This is accomplished by... 

Froth from the hot-water process may be mixed with a hydrocarbon diluent, eg, coker naphtha, and centrifuged. The Suncor process employs a two-stage centrifuging operation, and each stage consists of multiple centrifuges of conventional design installed in parallel. The bitumen product contains 1—2 wt % mineral (dry bitumen basis) and 5—15 wt % water (wet diluted basis). Syncmde also utilizes a centrifuge system with naphtha diluent. 

During World War II, production of butadiene (qv) from ethanol was of great importance. About 60% of the butadiene produced in the United States during that time was obtained by a two-step process utilizing a 3 1 mixture of ethanol and acetaldehyde at atmospheric pressure and a catalyst of tantalum oxide and siHca gel at 325—350°C (393—397). Extensive catalytic studies were reported (398—401) including a fluidized process (402). However, because of later developments in the manufacture of butadiene by the dehydrogenation of butane and butenes, and by naphtha cracking, the use of ethanol as a raw material for this purpose has all but disappeared. 

Two sources of absorption oil are normally utilized in this tower. The first is the hydrocarbon liquid from the main fractionator overhead receiver. This stream, often called wild, or unstabilized, naphtha, enters the absorber a few trays below the top tray. The second absorbent is cooled debutanized gasoline, which generally enters on the top tray. It has a lower vapor pressure and can be considered a trim absorbent. The expression lean oil generally refers to the debutanized gasoline plus the unstabilized naphtha from the overhead receiver. 

In 1992, researchers developed an engineering and costing design for a fixed unit that operated at a rate of 2 tons per hour. Costs were estimated to be 149 (Canadian) per metric ton of soil treated. This estimate was based on the following assumptions the unit used medium naphtha as a solvent operations were 24 hours per day, for 260 days per year utilization factor of the facility was 83% capital costs were 2,548 million (Canadian) and capital amortized over 10 years at 10%, two payments per year. The estimate stipulated that the recovered oil was of suitable quality to be sold to offset process costs. It was estimated that the largest component of process costs would be labor ( 56 per ton of waste treated). Other cost components listed were capitalization costs ( 38 per ton), utilities ( 29 per ton), insurance ( 9 per ton), trucking and maintenance (each 5 per ton), equipment rental and site excavation and restoration (each 3 per ton), and waste disposal was estimated to cost 1 per ton (D17896F, p. 8). 

This process is used to produce light gases, naphtha, distillate fuel, heavy fuel oil, and petroleum coke by cracking heavy residual products such as atmospheric and vacuum resids. Both delayed coking and fluid coking processes are utilized. 

Reforming Both thermal and catalytic processes are utilized to convert naphtha fractions into high-octane aromatic compounds. Thermal reforming is utilized to convert heavy naphthas into gasoline-quality aromatics. Catalytic reforming is utilized to convert straight-run naphtha fractions into aromatics. Catalysts utilized include oxides of aluminum, chromium, cobalt, and molybdenum as well as platinum-based catalysts. 

To specify charge stock characteristics, one of several options can be used specify a detailed gas chromatographic composition call the naphtha library estimate composition from general charge stock properties, such as PON A (% paraffins, olefins, naphthenes, and aromatics) and gravity or blend up to seven naphthas by utilizing the naphtha library. 

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. 

In the gas reversion process the recycle and outside C3-C4 stocks are heated separately for partial conversion before admixture with the naphtha. This bridges the difference in reaction velocity between the two types of charge and is helpful since the conversion rate of naphtha is approximately four times that of propane and twice that of butane, thereby decreasing the volume of C3-C4 recycle. Figure 10 shows a simplified flow diagram of a typical gas reversion operation. The extent to which outside C3-C4 stocks can be utilized is not limited, and the process can revert to thermal polymerization as the proportion is... 

In view of these considerations, a large amount of effort is reported in the scientific press on the development of a process to produce benzene from n-hexane by combined cyclization and dehydrogenation. w-Hexane has a low Research octane number of only 24.8 and can be separated in fair purities from virgin naphthas by simple distillation. Recently, an announcement was made of a process in the laboratory stage for aromatiza-tion of n-hexane (16). The process utilizes a chromia-alumina catalyst at 900° F., atmospheric pressure, and a liquid space velocity of about one volume of liquid per volume of catalyst per hour. The liquid product contains about 36% benzene with 64% of hexane plus olefin. The catalyst was shown to be regenerable with a mixture of air and nitrogen. The tests were made on a unit of the fixed-bed type, but it was indicated that the fluid technique probably could be used. If commercial application of this or similar processes can be achieved economically, it could be of immense help in relieving the benzene short-age. 

Implicit in Figure 2 are changes in investments and utility costs associated with severity changes. For the naphtha plant at 1000 MM lb/yr capacity, the investment in going from 27% severity to 23% is increased by about 1.9 MM the utilities cost increases by about 0.5 MM /yr. 

A possible solution is to gasify the more dilute vacuum tower bottoms product in an oxygen blown gasifier and to convert the excess synthesis gas to methanol. In those cases where a Flexicoker is used the heavy scrubber liquids could be recycled to extinction. Therefore, the plant products are SNG, naphtha, 300-800°F distillate and methanol. All of these products are of high quality or can be hydrotreated to achieve high quality. As a result, they could be easily integrated into the utility fuel mix with a minimum amount of disruption or special product handling facilities. 

Plant investment was prepared by the Dravo Corp. Gas price was presented on the basis of "a typical utilities guidelines which differed in many details from the utility financing method of C. F. Braun. In the case of COGAS, liquid product credit has a substantial effect on the gas price. In the paper this credit was at current market prices of 15.40/bbl for No. 4 fuel oil and 16.80 for naphtha. The resulting plant tailgate gas price on a 20-year operating time DCF basis was 5.08/MMBtu. However, if the liquids and gas are priced on an equivalent Btu basis, the fuel oil would be 25/bbl, the naphtha 27/bbl and the gas 4.10/MMBtu. These latter liquid prices are in the range of those estimated for liquids from coal by other processes. 

A brief outline of the products expected in a demonstration plant and in future commercial plants is shown in Figure 2. In future commercial plants, for example, ethane and propane could be utilized as chemical intermediates and naphtha as a source of chemicals or for production of high-octane unleaded gasoline. Synthesis gas produced in excess of the requirements for hydrogen could be utilized as a source of chemicals as well as a fuel. The fuel oil could be selectively fractionated to produce a middle distillate for use as turbine fuel, light industrial boiler fuel or refinery feedstocks, while the heavy distillate could serve as a fuel oil for large utility boilers. 

The liquids output represents a combination of transportation and utility fuels as summarized in Table III. All of the naphtha is to be reformed on site to produce a very high aromatic stock. With an exceptional octane blending value, this stream will find ready application as a gasoline component, but perhaps more important, it is also a source of substantial quantities of petrochemical raw materials as noted in Table IV. The potential yield of BTX and phenolics along with the low boiling paraffins should make such a plant an important factor in the future supply picture for these materials. 

PANELIST BLOOM I would say that COGAS talks very little about fuels for the utility market on the liquid side. The quality of the liquid product that we presently project is quoted as a No. 4 fuel oil and it is practically a No. 2. It really ought to be suitable for residential and commercial use. The naphtha we are talking about is a reformer feedstock and maybe a chemical feedstodk. 

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