Blends pour point

Stock % in blend. . Pour point ASTM 50%.temp, F... 

Low temperature filtration (qv) is a common final refining step to remove paraffin wax in order to lower the pour point of the oil (14). As an alternative to traditional filtration aided by a propane or methyl ethyl ketone solvent, catalytic hydrodewaxing cracks the wax molecules which are then removed as lower boiling products. Finished lubricating oils are then made by blending these refined stocks to the desired viscosity, followed by introducing additives needed to provide the required performance. Table 3 Usts properties of typical commercial petroleum oils. Methods for measuring these properties are available from the ASTM (10). 

The techniques of paraffin removal and paraffin prevention have been reviewed [810]. In particular, inhibitors for paraffin deposits are copolymers of ethylene with vinylacetate [525-527,1597] or polymers from p-nonylphenyl methacrylate and p-dodecylphenyl methacrylate [773]. These materials lower the pour point of the oil. It has been shown that for oils which differ in the content of n-paraffins and asphalt-resinous substances, it is necessary to use blends of copolymers of different compositions and molecular weights to obtain optimal efficiency. Polyacrylamide and wastes from the production of glycerol with a concentration of 400 mg/liter of oil have also been claimed to be effective as paraffin inhibitors [536]. 

As a general rule the pour point of a diesel fuel can usually be reduced by 5°F to 10°F (about 3°C to 5°C) for each 10% of kerosene added. The typical maximum blending volume of kerosene is about 30% by volume. 

FIGURE 4-6. Effect of Kerosene Blending on the Pour Point of Low-Sulfur... 

For most distillate fuels, cloud point temperatures can range from 50°F to -10°F (10.0°C to -23.3°C) or lower. However, typical cloud point temperatures fall between 6°F and 16°F (-14.4°C and -8.9°C). Distillate blends having a high paraffin content will often have cloud point and pour point values close together, sometimes within 5°F (2.8°C). Highly aromatic blends will usually have cloud and pour point values further apart in temperature. 

Lowering the cloud point and pour point values of a distillate fuel can be accomplished by blending the fuel with a low-wax-content distillate stream such as a kerosene or jet fuel. Also, additives are frequently used in conjunction with kerosene blending or as a substitute for kerosene blending to reduce the pour point of diesel fuel. Additives are not as frequently used to reduce the cloud point of diesel fuel. 

In present-day commercial practice, waxy oil charge is blended with 1 to 3 volumes of liquid propane at a temperature sufficiently high (120° to 160° F.) to ensure complete solution of the wax. The mixture is first cooled by exchange with cold filtrate and then charged to a batch chilling vessel, in which temperature is reduced to that required to obtain the desired pour point of the dewaxed oil, by evaporation of propane from the solution. Cold propane is injected into the vessel in order to maintain the propane-oil ratio approximately constant. The crystallized wax is removed by filtration on a continuous rotary filter (59) under a pressure of about 4 to 8 pounds per square inch. 

The properties of the fuel oil blend met the requirements for ASTM No. 4 fuel oil (usually considered a distillate fuel) except that its viscosity was low, falling between the specified requirements for No. 2 and No. 4 fuel oils (7 ), and its pour point of 30° F was higher than the ASTM-recommended maximum of 20° F. The fuel could be used as a low-sulfur, high-cetane-index grade 4-D diesel fuel in warm weather or where preheating facilities were available. 

Cold flow properties are of major importance in winter diesel. Cold performance limits are set to guarantee lack of crystallization. These are expressed as Cloud Point (CP), Pour Point (PP), or as Cold Filter Plugging Point (CFPP). For B100 biodiesel these have to be fully met with the biodiesel, and, if needed, with extra crystal retardation additives. In B2-B30 blends, though, the tendency is rather towards two types of Biodiesel, one for summertime (for example with CFPP of 0°C), and one for wintertime (for example with CFPP -10 °C). 

The optimum pyrolysis temperature is 395°C to give a recovery ratio of 0.97 (i.e. 1000 kg polystyrene will yield 970 L liquid monomer) and 5 to 10% char residue. Fuel made from polystyrene feedstock will be high in aromatic character and have an energy content of 50 MJ/kg and a pour point of —67°C. However the flash point is only 26°C and the cetane rating only 12.6. The fuel needs to be blended with polyolefin-derived diesel or regular diesel in order to upgrade the flash point and cetane rating to within specification. 

Optimal blending condition of 65 35 oil diluent (vol/vol) + 1% pour point depressants (PPD). 

While it is possible to treat an atmospheric residue from a Libyan crude direct, trace contaminants, particularly sodium, tend to poison the catalyst. However, this atmospheric residue can be vacuum-distilled to give a ca. 50 wt % yield of a 350°-550°C distillate containing 34 wt % wax, 72% of which is normal-paraffinic, and which is essentially free of catalyst poisons. This material can be catalytically dewaxed with Pt-H-mordenite in a ca. 70 wt % yield, resulting in a reduction of its pour-point from 115°F to values in the range 30° to 60 °F. This low-pour-point material can be blended back with the vacuum residue, which contains the catalyst poisons and only ca. 2 wt % n-parafEnic wax, to form a low-sulfur, low-pour-point fuel oil blending component (6). With this type of operation, catalyst activity can be maintained for long periods. 

The hydrocracking process often produces relatively large amounts of iso-butane that can be used in alkylation units to prepare alkylate for gasoline blending. Hydrocracking, depending on the catalyst, can also cause isomerization of the paraffinic products that benefit liquid fuels in terms of pour point control and smoke point. 

High naphtha and light olefin yields are favored by operation at high temperatures. The naphtha becomes excellent feed for naphtha crackers to make ethylene, the diesel is a green diesel with a cetane number of about 70, and obviously zero sulfur and aromatics, therefore it is an excellent blending component for poorer quality counterparts. The high molecular weight wax can either be cracked to fuels products or isomerized to reduce the pour point and produce lube base stocks. 

Viscosity/pour point Is a measure of HFO resistance to flow. They have high viscosity (depending on the grade) and often require heating for handling and combustion. The minimum heating temperature is defined by the pour point. The viscosity is not an additive property therefore oil blends have to be determined experimentally. 

Jet fuel is kerosene-based aviation fuel. It is medium distillate used for aviation turbine power units and usually has the same distillation characteristics and flash point as kerosene. Jet fuels are manufactured predominately from straight-run kerosene or kerosene-naphtha blends in the case of wide cut fuels that are produced from the atmospheric distillation of crude oil. Jet fuels are similar in gross composition, with many of the differences in them attributable to additives designed to control some fuel parameters such as freeze and pour point characteristics. For example, the chromatogram (Figure 27.4) of a commercial jet fuel (Jet A) is dominated by GC-resolved n-alkanes in a narrow range of n-C-j to n-Cig with maximum being around n-Ci. The UCM is well dehned. 

Asadauskas, S. S.Z. Erhan. Depression of pour points of vegetable oils by blending with diluents used for biodegradable lubricants./. Am. Oil Chem. Soc. 1999, 76, 313-316. 

Aromatic fractions can be alkylated with olefins to produce products which are used as synthetic lubricants.An aromatic fraction boiling between 160 and 210°C is generally alkylated with Cm to Cw olefins in a ratio of about 2 1. A higher-boiling aromatic fraction (boiling between 210 and 260°C) is reacted with Cs to Cw olefins in a ratio of 1 3. Aluminum chloride promoted with hydrogen chloride is the catalyst normally used. When the alkylated aromatics are blended with thickeners such as polyisobutylene, the mixture obtained is an excellent lubricant with a good viscosity index, stability, and pour point. 

In most cases, the additive depresses the pour point, which delays agglomeration of the wax crystals, but usually has no significant effect on diesel engine performance. A preferred means of improving cold flow is to blend kerosene with the diesel fuel, which lowers the wax appearance point by about 10° C for each 10% increment of kerosene added. 

Hot-applied polymeric sealants are formulated with a carefully balanced blend of polymer with certain compounds, like asphalt, plasticisers and inert reinforcing fillers to produce a hot-pour point sealant with excellent bonding properties, high resiliency, ductility and resistance to degradation from weathering, to provide a positive seal during expansion and contraction of the joint. 

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