Reducing pour point

Pour-point depressants Reduce pour points of waxy cmdes... 

In addition to dehazing, the Sonnebom white oil plant also reduced pour point from 4°C to 18°C and cloud point from +4°C to 10°C by removing 3 to 4% wax. This plant was unique in being a batch operation and being the first commercial use of this technology. Here, methanol was used as a promoter for adduct formation. 

BP found that it is possible to reduce pour points catalytically. A mordenite dual-function zeolite catalyst in the hydrogen form (to confer acidity and... 

Viscosity breaking aims to thermally crack long-chain feed molecules to shorter ones, thus reducing the viscosity and the pour point of the product. 

The lowest temperature at which fuel oil will flow. Residual oil (No. 6 oil) will not usually flow at ambient temperature and requires heating to reduce the viscosity and raise the pour point. 

The crystallization of waxes at lower temperatures causes reduced liquidity of waxy crude oils, which considerably hampers the transportation of crude oils through long distance pipelines. Taking into consideration all of the economic aspects, additive treatment, which depresses the pour point and improves the... 

Alternatively, the pour point is reduced by modifying the crude oil itself, for example, by cracking [655]. 

The other thermal cracking process is visbreaking. This is a milder thermal process and is mainly used to reduce the viscosities and pour points of vacuum residues to... 

Kerosene can be utilized effectively to reduce the pour point of most distillate fuels. The dilution limits are often based upon whether kerosene dilution will negatively impact fuel properties such as the viscosity, distillation parameters, sulfur limit, or cetane number. 

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. 

The most common type of wax crystal modifier used to reduce the pour point and filtration temperature of distillate fuel is based on ethylene vinylacetate (EVA) copolymer chemistry. These compounds are quite common throughout the fuel additive industry. The differences, however, are found in the variation in the molecular weight and the acetate ratio of the copolymer. 

Distillate fuel pour point temperatures can typically be reduced by 45°F to 60°F... 

The pour point and low-temperature viscosity of a residual fuel or heavy fuel oil can be reduced by using a heavy fuel wax crystal modifier. Often, pour point reversion can be prevented by using the correct wax crystal modifier. 

Fuels treated with a cloud point improver (CPI) may require additional CPI treatment whenever a wax crystal modifier is used to reduce the pour point of the fuel. Often, the cloud point of a CPI-treated fuel will increase whenever a pour point improver is used. To compensate for this phenomenon, additional CPI must be added to recover the lost performance. 

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. 

Crude oil and high-boiling-point, high-viscosity petroleum fractions such as 6 fuel oil, atmospheric tower bottoms, and vacuum gas oil can contain wax which crystallizes at temperatures often above room temperature. It is not unusual for these oils to have base pour points of 100°F (37.8°C) or greater. In order to utilize these heavy oils, the pour point and viscosity of these oils must be reduced. One method which is used to accomplish this is to dilute the heavy oil with lower-viscosity components such as diesel fuel or kerosene. The oil then becomes pumpable at lower temperatures. 

Basically, the process employs a selective solvent or mixture of solvents which have adequate oil solubility to permit operation at reduced temperatures without the separation of a second liquid or oil phase and in which the wax solubility is so low that the resulting dewaxed oil pour point is substantially the same as or within a few degrees of the dewaxing temperature. Generally, the solvent employed is a mixture of an aromatic solvent to obtain the required oil solubility and a polar solvent—for example, a ketone— to produce highly crystalline, easily filterable wax. 

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. 

A test was made with 2,3-dimethylbutane as the supercritical solvent it has a lower critical temperature than 2,2,4-trimethyl-pentane. Operating at a temperature of 508-512 K, a pressure of 4.10-4.37 MPa, a molecular sieve/oil ratio of 6.39, and a solvent/ oil ratio of 21.3, the molecular sieve capacity attained is 5.73 g/100 g of molecular sieves (as compared to 3.2 g/100 g of molecular sieves with 2,2,4-trimethylpentane at 550 K). The n-paraffin content of the wax distillate was reduced by 88% to a level of 2 wt %, giving a pour point of 266 K. The yield of denormal oil was lower (63%) and the n-paraffin content of the desorbate was lower (44%) at this lower temperature level. This is probably due to increased capillary condensation. Conversely, operation at temperatures greater than 550 K should produce less capillary condensation and purer n-paraffin product. It would be interesting to try supercritical solvents with critical temperatures in the 600-670 K range. 

The oil yields calculated from the analyses of the denormal products in Table III are plotted versus denormal product pour point in Figure 12. It is seen that 60% of the ii-paraffins must be removed before the pour point begins to decrease. Further extraction of the ti-paraffins to 88% of the theoretical (maximum) yield of 16.7 wt % n-paraffins then reduces the pour point from 294 K to 266 K. It appears that extraction of the remaining n-paraffins may lower the pour point to the desirable range of 261-255 K. It would be interesting to determine the effect of pour point depressants on the denormal oil product. 

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