Contents Hydrocarbons

The measurement of the vapor pressure and flash point of crude oils enables the light hydrocarbon content to be estimated. 

Unlike most crystalline polymers, PVDF exhibits thermodynamic compatibiUty with other polymers (133). Blends of PVDF and poly(methyl methacrylate) (PMMA) are compatible over a wide range of blend composition (134,135). SoHd-state nmr studies showed that isotactic PMMA is more miscible with PVDF than atactic and syndiotactic PMMA (136). MiscibiUty of PVDF and poly(alkyl acrylates) depends on a specific interaction between PVDF and oxygen within the acrylate and the effect of this interaction is diminished as the hydrocarbon content of the ester is increased (137). Strong dipolar interactions are important to achieve miscibility with poly(vinyhdene fluoride) (138). PVDF blends are the object of many papers and patents specific blends of PVDF and acryflc copolymers have seen large commercial use. 

Large-scale SCP production processes for growing yeasts of the genus Candida from hydrocarbon substrates were developed by British Petroleum Co., Ltd. and Kanegafuchi Chemical Industry, Ltd. of Japan (57). However, the 100,000-t/yr capacity plants based on these processes, and constmcted in Sardinia and Italy, were abandoned because of regulatory agency questions regarding residual hydrocarbon contents of the products (2,3). 

Because of the wide variation in the composition of natural gas as it is recovered at the wellhead and because natural gas can be used over a wide range of hydrocarbon contents, any specification for natural gas is usually broadly defined. However, the natural gas obtained at the wellhead usually undergoes some type of treatment or processing prior to its use for safety, economic, or system and material compatibiUty reasons. 

In the United States, the Compressed Gas Association Hsts nine grades of nitrogen, differentiated by oxygen content, dew point, total hydrocarbon content, and other contaminant levels (25). These grades, more often specified in government than commercial contracts, are shown in Table 3. 

A central location where instmment leads are short is preferred. In modem faciHties with distributed control systems, all units are controUed from a central control room with few operators. Only a few roving operators are available to spot trouble. It is desirable to deep process equipment a minimum of 8 m away from the control room. Any equipment and hydrocarbon-containing equipment should be separated by at least 15 m if possible. Most control rooms are designed with blastproof constmction and have emergency backup power and air conditioning. The room is pressuri2ed to prevent infusion of outside air that may have hydrocarbon content in the explosive range. 

The effect of increasing pressure is to move the average hydrocarbon content towards the heavier species, but increasing temperature seems to favour the production of lighter species. The final proportions are also determined by the state of the catalyst, and the physical anangement of tire reactor. The formation of the oxygenated compounds could also involve reactions between the H2O content of tire gas in the form of adsorbed OH radicals and hydrocarbon radicals since the production of these molecules is also well beyond the thermodynamic expectation. 

Disposal of Drainage of Process Equipment Contents - When items of onsite process equipment are taken out of service, either individually during plant operation or for general turnaround, means of draining and safe disposal of the residual liquid hydrocarbon contents must be provided. The following are important considerations and terminology in the design ... 

The term inventory refers to liquid hydrocarbon contents at the top of the working level range. Tray holdup is included, but piping contents are disregarded. 

Table 1 provides a summary of the safe practices applied to the disposal of liquid hydrocarbon contents from various sources. 

Example 8-20 Open Steam Stripping of Heavy Absorber Rich Oil of Li t Hydrocarbon Content (used by permission following the method of R. W. EUerbee, Chemical Engineering [127])... 

Batch with Constant Reflux Ratio, 48 Batch with Variable Reflux Rate Rectification, 50 Example 8-14 Batch Distillation, Constant Reflux Following the Procedure of Block, 51 Example 8-15 Vapor Boil-up Rate for Fixed Trays, 53 Example 8-16 Binary Batch Differential Distillation, 54 Example 8-17 Multicomponent Batch Distillation, 55 Steam Distillation, 57 Example 8-18 Multicomponent Steam Flash, 59 Example 8-18 Continuous Steam Flash Separation Process — Separation of Non-Volatile Component from Organics, 61 Example 8-20 Open Steam Stripping of Heavy Absorber Rich Oil of Light Hydrocarbon Content, 62 Distillation with Heat Balance,... 

These tests were performed to establish the limits in flexibility and operability of a methanation scheme. The two demonstration plants have been operated in order to determine the optimum design parameters as well as the possible variation range which can be tolerated without an effect on catalyst life and SNG specification. Using a recycle methanation system, the requirements for the synthesis gas concerning H2/CO ratio, C02 content, and higher hydrocarbon content are not fixed to a small range only the content of poisons should be kept to a minimum. The catalyst has proved thermostability and resistance to high steam content with a resultant expected life of more than 16,000 hrs. 

A. Hausberger As we mentioned earlier, the light hydrocarbons do not seem to affect catalyst activity, and they do reform into methane. However, you can increase the hydrocarbon content to levels where they do depress the methanation activity. If the hydrocarbons are high enough in unsaturation, they will form carbon when they get to a certain level. As far as hydrogen cyanide and ammonia are concerned, we don t expect them to affect the nickel methanation catalyst. 

Feedstock recycling processes for treating PVC rich waste streams should be eapable of recovering both the chlorine and hydrocarbon contents. ECVM sponsored research and development work to identify potential technologies for building a pilot plant is described. 3 refs. 

Purge gases used with liquid fluorine (—188°C or below) must be scrupulously dry and of low hydrocarbon content (<5 ppm), to prevent formation of ice crystals or solid hydrocarbons. 

The bulk of the naphtha was hydrotreated and catalytically reformed over a chlorided Pt/Al203-based catalyst to produce an aromatic motor gasoline. However, the hydrotreated Fischer-Tropsch naphtha is a poor feed for standard catalytic reforming on account of its high linear hydrocarbon content (>75%).37 In order to limit liquid yield loss, typical operation resulted in a reformate with quite low octane value (Table 18.10). Higher octane reformate could be produced, but at the expense of significant liquid yield loss. 

Wade and Quinn [12] measured the hydrocarbon content of sea surface and subsurface samples. Hydrocarbons were extracted from the samples and analysed by thin-layer and gas-liquid chromatography. The hydrocarbon content of the surface micro layer samples ranged from 14 to 599 pg/1 with an average of 155 pg/1, and the concentration in the subsurface samples ranged from 13 to 239 pg/1 and averaged 73 pg/1. Several isolated hydrocarbon fractions were analysed by infrared spectrometry and each fraction was found to contain a minimum of 95% hydrocarbon material, including both alkenes and aromatics. 

Zsolnay A (1974) Determination of aromatic and total hydrocarbon content in submicrogram and microgram quantities in aqueous systems by means of high-performance liquid chromatography. Special publication no. 409. National Bureau of Standards, Washington, DC, p 119... 

An oil containing 2.55 mole per cent of a hydrocarbon is stripped by running the oil down a column up which live steam is passed, so that 4 kmol of steam are used/100 kmol of oil stripped. Determine the number of theoretical plates required to reduce the hydrocarbon content to 0.05 mole per cent, assuming that the oil is non-volatile. The vapour-liquid relation of the hydrocarbon in the oil is given by ye = 33x, where ye is the mole fraction in the vapour and x the mole fraction in the liquid. The temperature is maintained constant by internal heating, so that steam does not condense in the tower. 

Similar reductions in permeability were found for C02 and N2. Apparently this treatment method creates a universal gas barrier and is seemingly universal for polymers with a high hydrocarbon content. It is anticipated that by optimizing this approach, 02 permeability values for PE of less than 50 cm7m2 per 24 h will be achieved. 

Total cost assessment (TCA), 12 814 Total developed pump head, 21 57—58 Total dissolved solids (TDS), 21 646, 647 reverse osmosis removal of, 25 890 in wastewater, 25 887 Total fiber scutching, 11 612-613 Total hydrocarbon content (THC), of oxygen, 17 759-760... 

No recent studies could be identified that were performed in the United States on levels in expired air. A study of hydrocarbon contents in expired air in the Chicago area carried out in the late 1970s found average w-hcxanc concentrations from 54 human volunteers breathing urban air to be approximately 4.7 ng/L (Krotoszynski et al. 1979). Most studies of -hexane have involved occupational exposures, especially in shoe or sandal factories, in Japan or Italy. Since -hexane is rapidly metabolized by humans to such compounds as 2,5-hexanedione, investigations of toxic substances in blood or urine typically focus on these metabolites (Mutti et al. 1993 van Engelen et al. 1995). In one study of shoe assembly... 

The Curie Point flash evaporation-pyrolysis gas chromatography-mass spectrometric method [32] described in section 2.2.1.2 for the analysis of aliphatic hydrocarbons in soils has also been applied to the determination of polyaromatic hydrocarbons (see Table 2.1). Table 2.2 lists the polyaromatic hydrocarbon contents found by this method in a soil sample. 

A 10-yd3 soil sample was excavated from the site, blended, and characterized for initial hydrocarbon content and nutrient content. The reactor was filled with soil compacted to field density (Figure 12.10). The tank at the bottom was filled with water nutrients and surfactants. Water from this tank was sprayed over the top of the soil at a rate that maintained aerobic conditions. A significant amount of LNAPL was initially released from the soil, which required additional air to be pumped into the well points to maintain favorable growth conditions. After 105 days of operation, more than 87% of the total aliphatics and 89% of the total aromatics were removed. 

Total Organic Carbon Formations with a significant TOC content greater than the petroleum hydrocarbon content, as with peat-rich soil, can compete with the hydrocarbon-degrading microbes for oxygen and nutrients. A representative sample should thus be analyzed for TOC if organic matter is observed in soil samples or borings. 

The conventional technology of pipeline calculations does not normally predict the carbon dioxide or hydrocarbon content of the water rich phase. These can be estimated by other graphical correlations. 

Although the calculated phase compositions for the hydrocarbon - rich liquid phase and the vapor phase showed excellent agreement with the experimental data, the calculated hydrocarbon contents of the aqueous liquid phase was consistently several orders of magnitude lower than the reported experimental values. 

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