Hydrocarbon production, light

Volume of olefin/(volume of ionic liquid.hour). i-C = 2,2- and 2,3-dimethylbutanes, i-Cg = isooctanes, TMP trimethylpentanes, = hydrocarbon products with more than eight carbon atoms, Light ends = hydrocarbon products with fewer than eight carbon atoms, RON = research octane number, MON = motor octane number... 

Another vital part of such projects is contaminant removal. Notwithstanding the hydrogenation of the DCC VGO feedstock, the light hydrocarbon products from such units will contain a range of contaminants at various concentrations depending upon upstream operating conditions ... 

The physical processes by which natural gas liquids are recovered include phase separation, cooling, compression, absorption, adsorption, refrigeration, and any combination of these. Obviously the definition already stated excludes refinery light volatiles produced by the destructive decomposition of heavy petroleum fractions and it also excludes liquids that may be produced synthetically from natural gas. These distinctions are of economic importance in considering our basic energy reserves. Both the refinery volatiles and the synthetic liquids represent conversion products from other hydrocarbons and the conversion is usually attended by a considerable loss. Thus it has been stated that only about 47% (17) of the energy of natural gas is realized in the liquid hydrocarbon products of the Fischer-Tropsch type of synthesis. 

The Cyclar process converts C3 and G paraffins to aromatics via a bifunctional zeolitic catalyst (25). Typical aromatic yields in Table 3.11 are 70 wt-%, with 6 wt-% hydrogen yields. The light hydrocarbon products can be used as fuel for the plant. Cyclar can be considered for remote locations as an alternative to flaring LPG, or when refrigerating LPG for shipment is not economical. 

The reaction mechanism for the conversion of methanol to hydrocarbons over molecular sieve catalysts has been extensively investigated over the past 25 years. It is widely accepted that methanol conversion initially proceeds through equilibration with DME. Early work with ZSM-5 showed that light olefins are then the initial hydrocarbon products, followed by heavier olefins, paraffins and aromatics (Figure 12.5) (2). 

The Synthol light oil (Cs-Ci ) is highly olefinic and is isomerized over an acidic catalyst to improve the octane rating of the gasoline. The hydrocarbon products from the fixed-bed reactors arc distilled to separate the gasoline and diesel oil. The residue is vacuum-disiilled to produce medium wax (320 500 C) and hard wax (>500 C). Both products arc hydrofined using nickel catalysts to remove olefins and oxygenates. 

The deasphalting process is also based on carbon removal [4]. However, it uses a completely different technology. Here, asphaltenes are extracted by solvents from the heavy ends. Light hydrocarbon (e.g. propane) or supercritical gases are used as solvents. The resulting deasphalted oil is essentially free of metallic contaminants. The carbon removal processes yield large amounts of low-value coke or asphalt beside the desired hydrocarbon products. 

To recover a maximum of olefins and butadiene from recycling polyolefins, it is necessary to have a short residence time of the product gases in the fluidized bed zone to avoid no secondary reactions. The pyrolysis gas should not be circulated and used as fluidizing gas. For the experiments, steam was used as fluidizing gas [13, 14]. An easy separation of the hydrocarbon products is possible by condensation to water in a cooler. The results are shown in Table 17.6. As feedstock a light plastic fraction from household waste separation was used which contains 95.8% of PE and PP, 3% of PS, and 0.2% of PVC. 

Light hydrocarbon products were analyzed with a P E F-ll gas chromatograph with a benzyl cyanide-silver nitrate column and flame ionization detector. No effort was made to recover and analyze heavy hydrocarbons. 

Oil producers will typically set standards for oil-in-water content ranging from less than 10 ppm in very light crude oils to several hundred parts per million in very heavy crude oils. These specifications are usually site-specific and are dependent on equipment available and crude-oil type. Oil producers in Canada usually have the advantage of disposal wells or water-flood schemes in which produced water is disposed. Failure to meet self-imposed oil-in-water limits usually results in loss of hydrocarbon product back to the formation. For an oil production facility that disposes of 1000 m of water per day with an oil content of 1000 ppm, 365 m of oil is lost per year. At 25 (Canadian) per barrel, this amount of oil translates to a product loss worth approximately 57,000 per year, plus any maintenance costs and well stimulation costs to restore injectivity lost as a result of formation plugging from oil-wet solids. Oil-wet solids in water-flood systems may damage formation permeability and reduce recovery. 

Literature review of biogenic light hydrocarbon production (C1-C4)... 

In the years following these early studies, the basic concepts have remained largely the same, except that detection limits have been improved with technological advances. Recent work has focused on compositional ratios or signatures of the light hydrocarbon gases and their relationship to known hydrocarbon products in the investigated area (Weismann 1980 Jones and Drozd, 1983). 

Janezic, G.G., 1979. Biogenic light hydrocarbon production related to near-surface geochemical prospecting for petroleum (abs.). Amer. Assoc. Pet. Geol. Bull., 63 403. 

Nevertheless, the world economy remains oil-based and the production of almost the whole range of petrochemical and bulk organic chemical products (with a few exceptions, like methanol, urea, and cyanic acid) is still oriented toward the processing of liquid fossil hydrocarbons as the principal raw materials. Also, the same liquid hydrocarbons dominate in the production of motor fuels and lubricants. However, most if not all of the products traditionally produced from oil can be also obtained from gaseous hydrocarbons, including light alkanes. Unfortunately, up to now their utilization in the chemical industry is not satisfying. 

---