On the quality analysis of hydrogenated oil products

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1. Analysis of the general properties of the product: density, API, characteristic factor, related indices, average molecular weight, residue, ash content, boiling range, aniline point, refractive index, net calorific value. Flow properties: kinematic viscosity, pour point, freezing point, cold filter plugging point, freezing point, cloud point. Safety properties: flash point, vapor pressure, ignition point, auto-ignition point, copper sheet corrosion. Performance properties: smoke point, octane number, cetane number, cetane index. Impurities: mechanical impurities, water content, acid value, salts, acidity, mercaptan sulfur, basic nitrogen. Elements: non-metals (sulfur, nitrogen, carbon, hydrogen, oxygen), metals (iron, nickel, copper, vanadium, lead, calcium, magnesium, sodium). Chemical composition: n-alkanes, isoparaffins, cycloparaffins, aromatics； Alkanic carbon, cycloalkanic carbon, aromatic carbon ； Wax content ； Saturated fraction, aromatic fraction, resin, asphaltenes 2; Selection of analysis parameters for naphtha (IBP-200°C): density, boiling range, volume percentage yields of normal alkanes, isoparaffins, cycloparaffins, olefins, aromatics, and benzene, composition of monohydrocarbons, acid value, research octane number, vapor pressure, sulfur, nitrogen, thiols, copper sheet corrosion. Reforming feedstock: Used for the production of aromatics; it can be distilled in the range of 65–145°C, as this is exactly the boiling point range for benzene, toluene, and xylene. For the production of high-octane gasoline, it can cut in the range of 80–180°C. Since it has a high octane number at temperatures below 80°C, reforming is not required. If the cutting point exceeds 180°C, the final boiling point of the reformed gasoline will exceed 205°C. In addition to straight-run gasoline, the analysis items should also include arsenic, copper, lead, trace water, and aromatic potential. Aviation fuel (140–240°C): density, boiling range, hydrocarbon composition (content of aromatics, olefins, and saturated hydrocarbons in volume percentage), sulfur, thiols, acid value, closed-cup flash point, aniline point, freezing point, kinematic viscosity (-20°C, 20°C, 40°C), net calorific value, smoke point, copper strip corrosion, nitrogen, color (Saytzeff). Straight-run diesel (200–350°C): density, boiling range, hydrocarbon composition (aromatics), sulfur, thiols, nitrogen, acid value, closed-cup flash point, color (ASTM D1500), copper strip corrosion, kinematic viscosity (20°C), freezing point, pour point, cold filter plugging point, aniline point, cetane number. 3. Definition of the aniline point: The lowest temperature at which a petroleum product, under specified conditions, is mixed with an equal volume of aniline until the two dissolve in each other to form a homogeneous liquid. Various hydrocarbons have different solubilities in aniline, and thus different aniline points. Aromatic anilines have the lowest point, naphthenes are in the middle, and alkanes have the highest. Residue: The charred black residue formed when oils burn in insufficient air, mainly consisting of gums and asphaltenes. . The mass fraction is expressed in %. The higher the residue value of the oil, the greater its tendency to form carbon deposits. Ash: The inorganic substance obtained by calcining the residue left after burning the sample under specified conditions, expressed as a mass percentage. Refractive index: The refractive index is used to determine the composition of liquid mixtures. Dynamic viscosity: The unit of dynamic viscosity is Pa·s, and its physical meaning is the internal friction force generated when two layers of liquid, each with an area of 1 m2 and separated by a distance of 1 m, move relative to each other at a speed of 1 m/s. Dynamic viscosity is the ratio of a liquid’s dynamic viscosity η to its density ρ at the same temperature, and it is a physical property. It is mainly used to measure lubricating oils. Pour point, freezing point, cold filter plugging point, freezing point, cloud point: The cloud point refers to the highest temperature at which, under test conditions, microcrystals of hydrocarbons or water mist begin to appear, causing the oil to become cloudy. After the oil reaches its cloud point, it continues to be cooled until visible crystals appear in the oil; this temperature is the crystallization point of the oil. When the temperature is raised further, the crystals disappear, and this temperature is the freezing point, which is generally 1-3°C higher than the crystallization point. The dew point is the temperature at which the oil sample is cooled under specified conditions; the test tube is removed every 3°C and placed horizontally to observe whether there is any movement in the liquid level of the sample, and it is the temperature at which no movement occurs in the sample level after 5 seconds, plus 3°C. The freezing point refers to the temperature at which an oil loses its fluidity, as measured under specified test conditions using a designated instrument (with the test tube tilted at 45°, and no visible movement of the oil surface after one minute). The essence of the freezing point is that, at low temperatures, the viscosity of the oil increases, resulting in the formation of an amorphous glass-like substance that loses its fluidity; or in the case of waxy oils, the wax crystals accumulate and form a network structure, with this crystalline framework enclosing the liquid oil and preventing it from being fluid. Alkanes have the highest freezing point, while aromatics have the lowest. For the same oil, the cloud point > freezing point > crystallization point > pour point > freezing point. Flash point, ignition point, auto-ignition point: Flash point: The lowest temperature at which, under specified test conditions, an mixture of vapor and air emitted when the oil is heated comes into contact with a flame, resulting in an instantaneous flash fire, expressed in °C. The open flash point is used to determine heavy oils, while the closed flash point is used to determine light oils. A temperature of 45°C is used as the boundary to distinguish between combustible materials and flammable materials. Ignition point: The lowest temperature at which a petroleum product, when heated under specified conditions, can be ignited by an external source of fire and continue to burn for at least 5 seconds. Auto-ignition point: The lowest temperature at which a petroleum product can undergo spontaneous combustion when heated, without the need for an external ignition source, as intense oxidation occurs within the material itself. Flash point < Ignition point < Spontaneous ignition point. Copper sheet corrosion: A qualitative method to determine the presence of active sulfides or free sulfur. Smoke point: The maximum height at which the fuel flame produces no smoke. The smoke point is a specification parameter that controls the carbon deposition resistance of aviation fuel. The higher the smoke point, the better, as it indicates a lower tendency for the fuel to form carbon deposits. The higher the content of aromatic hydrocarbons, the lower the smoke point. The distillate becomes heavier, and the smoke point decreases. An increase in the content of unsaturated hydrocarbons results in a lower smoke point. A higher actual gel content results in a lower smoke point. Octane number: Isooctane is used as a standard with excellent anti-knock properties, and its octane number is set at 100 ； Heptane is used as a standard for poor anti-knock properties, with an octane rating of O. By mixing these two hydrocarbons in different volume ratios, standard fuels with octane numbers ranging from 0 to 100 can be prepared. The higher the volume percentage of isooctane in the mixture, the better its anti-knock properties. The RON measurement method is used to measure low and medium speeds. Motor Method MON for measuring high-speed cetane number: Under specified test conditions, it determines the ignition performance of diesel, and the resulting value is obtained by comparing it with the ignition performance of a standard fuel of fixed composition (a mixture of hexane with a cetane number of 100 and α-methylnaphthalene with a cetane number of 0). The higher the content of n-alkanes in diesel, the higher its cetane number, as well as its combustion performance and cold-startability; however, its boiling point and freezing point will increase. Acid value and acidity: Acidity refers to the number of milligrams of potassium hydroxide (KOH) required to neutralize 100 mL of the test oil [KOH]/100mL]; this value is generally applicable to light oils ； The acid value refers to the number of milligrams of potassium hydroxide (KOH) required to neutralize 1 g of the oil sample [KOH/g], and this value is generally applicable to heavy oils. Acidity = Acid value * 100 * d. BMCI value: Also known as the aromatic index, this value indicates the level of aromatics in the oil; a higher value means a higher content of aromatics. Its basis is that the BMCI value of n-hexane is set at 0, and the BMCI value of benzene is set at 100. Determine whether it is a high-quality ethylene cracking feedstock. BMCI=48640/（t_body+273）+473.7*d15.615.6-456.8