Method for determining the density of heavy oil and application thereof

Abstract

The application provides a heavy oil density determination method and application. The determination method comprises the following steps: filling heavy oil into a cleaned metal container, and then testing the heavy oil density by a weighing method. A cleaning device for cleaning the metal container comprises a heating unit, a heat preservation unit and a storage tank. Compared with the densimeter method, the method can directly determine the heavy oil density at 20 DEG C, and avoids the deviation caused by the conversion after the determination temperature is too high. Compared with the pycnometer method, the metal cylinder is used to contain the sample, the sample amount is increased, the result is more representative, the metal cylinder is convenient to clean and is not easy to be damaged, and the cleaning solvent can be recycled and reused.

Description

Technical Field

[0001] This invention relates to the field of heavy oil analysis and measurement technology, specifically to a method for determining the density of heavy oil and its application. Background Technology

[0002] Heavy oil primarily originates from residues or blends generated during petroleum processing. During petroleum processing, crude oil can be broken down into hydrocarbon compounds of different types and molecular weights through processes such as distillation. The fractions with lower molecular weights and lighter densities are called light oils, including gasoline, kerosene, and diesel; the substances with higher molecular weights and greater densities are heavy oils. Generally, heavy oil is an oil product with an initial boiling point greater than 350℃ after Engel distillation (compliant with national standard GB / T6536-2010). Density is one of the most fundamental and important properties of heavy oil, therefore, its determination is of great significance. In my country's national standards, there are two methods for measuring the density of petroleum products: the hydrometer method (GB / T 1884-2000) and the specific gravity bottle method (GB / T13377-2010).

[0003] The hydrometer method is based on Archimedes' principle. When a hydrometer sinks into a liquid, it displaces a portion of the liquid and experiences an upward buoyant force equal to the weight of the displaced liquid. When the hydrometer is stationary, the weight of the displaced liquid equals the weight of the hydrometer itself, i.e., the mass of the oil per unit volume, which is called the density of the oil. However, for samples with high pour points, the fluidity is poor at room temperature, making direct determination of standard density (usually at 20℃ or 15℃) impossible. It is necessary to heat the sample to a more fluid state before measurement, and then convert the observed density reading to standard density using a petroleum gauge. When the petroleum is too viscous, the hydrometer cannot float freely in a graduated cylinder, and dark petroleum residue on the hydrometer's scale affects the reading, leading to inaccurate results. In this case, dilution with kerosene or diesel oil is necessary. Dilute with an equal volume of kerosene or diesel oil of known density (ρ2), measure the density of the mixed oil (ρ1), and then calculate the density ρ of the petroleum using the formula ρ = 2ρ1 - ρ2. However, this dilution density method requires light oil. The partial molar effect of volume shrinkage during the mixing of light and heavy distillate oils often results in a lower density. Furthermore, since the sample volume changes with temperature, the test temperature affects the density measurement results. Lower test temperatures result in smaller changes to the hydrocarbon structure and volume of the sample, leading to more accurate results.

[0004] The specific gravity bottle method uses gravimetric analysis, which has the following drawbacks: (1) The specific gravity bottle has a small capacity, resulting in a small sample size and low representativeness. (2) The specific gravity bottle has a small opening, making it easy for heavy oil to stick to the bottle opening when entering, and cleaning is inconvenient. (3) The sensitivity of the weighing balance is no more than 1 mg, and it is greatly affected by the ambient temperature. The entire process requires multiple measurements, which can easily cause errors. (4) The operation is complicated and the conditions are demanding, resulting in low accuracy of the results; the small bottle is difficult to operate and is easily damaged. (5) Due to the high viscosity of heavy oil, a large amount of light oil is required for cleaning, which can easily cause environmental pollution during subsequent cleaning. Summary of the Invention

[0005] To address the technical problems of high operational difficulty and large measurement error in the existing heavy oil density measurement, this invention provides a method for determining the density of heavy oil, which involves using a metal container containing a metal cylinder and a support to hold the heavy oil, cleaning the metal container with a cleaning device, and then testing the density of the heavy oil by weighing.

[0006] One objective of this invention is to provide a method for testing the density of heavy oil, comprising the steps of filling a cleaned metal container with heavy oil and then testing the density of the heavy oil by weighing. The cleaning device for cleaning the metal container includes a heating unit, a heat preservation unit, and a storage tank. The heating unit is used to heat the cleaning solvent to clean the metal container. The heat preservation unit is used to keep the metal container warm during the cleaning process. The storage tank is used to provide the cleaning solvent and collect the cleaning solvent after cleaning.

[0007] According to the present invention, the metal container includes a metal cylinder and a support. The metal cylinder has external threads at both ends, and the inner wall of the support has internal threads. The two ends of the metal cylinder and the support are tightly connected by threads to form a sealed metal container. Specifically, the metal cylinder is a cylindrical metal tube that is not top- or bottom-sealed, with external threads at both ends, which can be tightly connected with the internally threaded support to form a sealed space.

[0008] According to the present invention, the heating unit in the cleaning device includes a cleaning solvent container and an electric heating system. A circular hole is provided in the center of the top cover of the cleaning solvent container, and the diameter of the hole is larger than the cross-sectional diameter of the metal cylinder. The circular hole can be tightly connected to the external thread at one end of the metal cylinder by providing an internal thread, or it can be tightly fitted to one end of the metal cylinder by adding a rubber ring. A heavy oil outlet is provided at the bottom of the cleaning solvent container for discharging the heavy oil collected after cleaning the metal container.

[0009] According to the present invention, the method for testing the density of heavy oil specifically includes the following steps:

[0010] (1) After cleaning and drying the metal container, the first weighing is performed to obtain m1.

[0011] (2) After the metal container is kept at a constant temperature in a constant temperature water bath at temperature t1, the metal container is filled with water at temperature t1 and weighed a second time to obtain m2.

[0012] (3) After heating the heavy oil to be tested to a fluid state, add the heavy oil sample to the metal container using a metal funnel, and weigh it a third time after cooling to obtain m3.

[0013] (4) After placing the metal container containing the heavy oil sample to be tested in step (3) in a constant temperature water bath at temperature t1, fill the metal container containing the heavy oil to be tested with water at temperature t1 and weigh it for the fourth time to obtain m4.

[0014] (5) Calculate the density ρ of the heavy oil sample to be tested according to the following formula:

[0015] ρ=ρ w ×(m3-m1) / [(m2-m1)-(m4-m3)]

[0016] In the formula, ρ: density of the heavy oil to be tested at temperature t1, g / m³ 3 ;ρ w Density of water at temperature t1, in g / m³ 3 .

[0017] According to an embodiment of the present invention, in step (1) of the heavy oil density testing method:

[0018] The cleaning solvent used is an oil product with a final boiling point of less than 200°C, which is distilled using Engel distillation (compliant with national standard GB / T 6536-2010). It is preferably selected from at least one of petroleum naphtha, petroleum ether, and n-heptane. Specifically, it can be an intermediate product of oil refining and chemical plants, such as naphtha, or commercially available light oil products such as petroleum ether and n-heptane.

[0019] The drying method after cleaning can adopt common drying methods and drying process conditions. For example, the drying temperature after cleaning is 80-140℃, preferably 100-110℃.

[0020] According to an embodiment of the present invention, the cleaning in step (1) includes: tightly connecting the lower end of the metal cylinder to the heating unit (by means of thread or rubber ring, etc.), tightly connecting the upper end of the metal cylinder to the condenser pipe joint of the storage tank by thread, and wrapping the outer wall of the metal cylinder with an insulation unit; then conveying the cleaning solvent in the storage tank to the heating unit, heating the cleaning solvent to clean the metal cylinder, and condensing the cleaning solvent after cleaning back into the storage tank; preferably, the temperature of heating and cleaning is 90-150°C;

[0021] The cleaning in step (1) also includes the step of heating and cleaning the cylinder tray with a cleaning solvent. For example, the cylinder tray is placed in a heating unit and heated with a cleaning solvent for cleaning, or a commonly used cleaning method is used to rinse it with a heated cleaning solvent. Preferably, the temperature for heating and cleaning is 100 to 150°C.

[0022] According to an embodiment of the present invention, in step (2) of the heavy oil density testing method;

[0023] The temperature t1 of the constant temperature water bath can be a commonly used test temperature, such as any temperature in the range of 15 to 20℃, for example, 15℃, 16℃, 17℃, 18℃, 19℃ or 20℃.

[0024] The constant temperature water bath time is not less than 1 hour, preferably 1 to 2 hours; specifically, the constant temperature water bath operation in step (2) includes: immersing the metal cylinder with the cylinder support at both ends in water at temperature t1 for a constant temperature water bath of not less than 1 hour.

[0025] Step (2) also includes the steps of emptying the metal container after weighing and drying it. After the metal container is dried, it is convenient to fill it with heavy oil for density testing. The drying method can be a commonly used drying method and drying process conditions, for example, the drying temperature is 80 to 140°C.

[0026] According to an embodiment of the present invention, in step (3) of the heavy oil density testing method, the heating condition for the heavy oil to be tested is: the heating temperature does not exceed 25°C above the pour point of the heavy oil to be tested. The heavy oil does not have fluidity at temperature t1. After heating the heavy oil to be tested in a heating device until it reaches a fluid state, it is poured into a metal container using a metal funnel, cooled, and weighed to calculate the mass of the heavy oil to be tested.

[0027] According to an embodiment of the present invention, in step (3) of the heavy oil density test method, the volume of the heavy oil sample to be tested added to the metal container is 70-90% of the total volume of the metal container, preferably 75-85%.

[0028] According to an embodiment of the present invention, in the heavy oil density testing method:

[0029] The temperature t1 of the constant temperature water bath in steps (4) and (2) is the same, and the temperature t1 of the constant temperature water bath is 15-20℃;

[0030] The constant temperature water bath time in step (4) shall be no less than 2 hours, preferably 2 to 3 hours; specifically, the constant temperature water bath operation in step (4) includes: after connecting one end of the metal cylinder through the cylinder support, injecting the heavy oil sample to be tested, connecting the other end of the metal cylinder to the cylinder support and sealing it, immersing it in water at temperature t1 for a constant temperature water bath of no less than 2 hours.

[0031] According to an embodiment of the present invention, the metal container can be made of commonly used metal materials, such as stainless steel.

[0032] The second objective of this invention is to provide a method for testing the density of the aforementioned heavy oil for testing the density of oils produced by Engel distillation (compliant with national standard GB / T 6536-2010) with an initial boiling point greater than 350°C, wherein the oil does not have fluidity at temperature t1.

[0033] The technical advantages of this invention are as follows: The method for determining the density of heavy oil provided by this invention uses a balance to weigh the heavy oil, typically measuring the density at 20°C. Compared to the hydrometer method, directly measuring the density of heavy oil at 20°C avoids the deviation caused by converting the measurement at a higher temperature. Compared to the specific gravity bottle method, using a metal cylinder to hold the sample increases the number of samples, resulting in more representative results. The metal cylinder is easy to clean, not easily damaged, and the cleaning solvent can be recycled and reused. Attached Figure Description

[0034] Figure 1 This is a schematic diagram of the metal container cleaning device of the present invention. Wherein, 1-metal cylinder; 2-insulation unit; 3-heating unit; 4-storage tank; 5-cleaning solvent outlet valve; 6-heavy oil vent valve. Detailed Implementation

[0035] The present invention will now be described in detail with reference to specific embodiments and accompanying drawings. It should be noted that the following embodiments are only used to further illustrate the present invention and should not be construed as limiting the scope of protection of the present invention. Some non-essential improvements and adjustments made by those skilled in the art based on the content of the present invention are still within the scope of protection of the present invention.

[0036] As a preferred embodiment of the present invention, the method for determining the density of heavy oil provided by the present invention specifically includes the following steps:

[0037] (1) The metal cylinder is placed in a cleaning device for cleaning and then dried. The first weighing is performed to obtain m1.

[0038] (2) After placing the metal container in a constant temperature water bath at temperature t1, fill the metal container with water at temperature t1, weigh it a second time to obtain m2, empty the metal container and dry it.

[0039] (3) After heating the heavy oil to be tested to a fluid state, the heavy oil sample to be tested is added to the metal container using a metal funnel. After cooling, the sample is weighed a third time to obtain m3.

[0040] (4) After placing the metal container containing the heavy oil sample to be tested in step (3) in a constant temperature water bath at temperature t1, fill the metal container containing the heavy oil sample to be tested with water at temperature t1, wipe off the surface water, and weigh it for the fourth time to obtain m4.

[0041] (5) Calculate the density ρ of the heavy oil sample to be tested according to the following formula:

[0042] ρ=ρ w ×(m3-m1) / [(m2-m1)-(m4-m3)]

[0043] In the formula, ρ: density of the heavy oil to be tested at temperature t1, g / m³ 3 ;ρ w Density of water at temperature t1, in g / m³ 3 .

[0044] The metal cylinder is an open-top cylindrical metal tube with external threads at both ends, which can be connected to a cylinder support with internal threads to form a sealed metal container. During cleaning, the lower end of the metal cylinder is tightly fitted to the top cover of the cleaning solvent container of the heating unit via a threaded connection or with a rubber ring. The upper end of the metal cylinder is tightly connected to the condenser tube structure via threads. The outer wall of the metal cylinder is wrapped with an insulation unit to achieve temperature-controlled heating. Then, the cleaning solvent in the storage tank is transported to the heating unit, and the heated cleaning solvent cleans the metal cylinder. The cleaned cleaning solvent condenses and flows back to the storage tank. The heavy oil cleaned on the inner wall of the metal cylinder is collected in the container of the heating unit and then discharged through the outlet valve.

[0045] After the test, open the water-filled end of the metal container (upper support) to pour out the water. Then connect this end to the heating unit of the cleaning device. The outer wall of the metal cylinder is wrapped with an insulation unit. The heavy oil sample is heated and discharged. After removing the other end of the metal container, connect the condenser pipe connector to transfer the cleaning solvent in the storage tank to the heating unit. The cleaning solvent is heated to clean the metal cylinder. The support is placed in a container containing the cleaning solvent and heated for cleaning. After cleaning, the metal cylinder and support are dried and ready for use.

[0046] The heavy oil is an Engel distillation product (compliant with national standard GB / T 6536-2010) with an initial boiling point greater than 350℃ and no fluidity at t1. The cleaning solvent is an Engel distillation product (compliant with national standard GB / T 6536-2010) with a final boiling point less than 200℃, which can be an intermediate product of oil refining and chemical plants such as naphtha, or commercially available light oil products such as petroleum ether, n-heptane, etc.

[0047] The constant temperature water bath in step (2) includes: immersing the metal cylinder with a support at both ends in water at temperature t1 for at least 1 hour.

[0048] In step (3), the heavy oil to be measured is placed in a heating oven and heated until it is in a fluid state. Then, it is added to the metal container using a metal funnel and cooled before the third weighing is performed.

[0049] The constant temperature water bath in step (4) includes: immersing the metal container after injecting the heavy oil sample into water at temperature t1 for at least 2 hours in a constant temperature water bath, then opening the upper tray of the metal container to fill it with water at temperature t1, connecting the upper tray and performing a fourth weighing.

[0050] The present invention will be further described in detail below with examples, but the present invention is not limited thereto.

[0051] The apparatus and materials used in the embodiments and comparative examples are as follows:

[0052] Metal cylinder: made of stainless steel (Inner diameter)×200mm.

[0053] Densitometer: Ten-piece set of petroleum densitometers (0.600-1.100 g / cm³) 3 ).

[0054] Materials: Heavy oil A and heavy oil B, both derived from the same crude oil. Heavy oil A is the atmospheric residue fraction obtained by true boiling point distillation of the crude oil (i.e., the fraction with a temperature >350℃ after distillation), and heavy oil B is the vacuum residue fraction obtained by true boiling point distillation of the crude oil (i.e., the fraction with a temperature >540℃ after distillation). Their basic properties are shown in Table 1.

[0055] Table 1. Basic Properties of Crude Oil and Heavy Oil A and Heavy Oil B

[0056] project crude Heavy oil A Heavy oil B Pour point / °C -5 22 62 <![CDATA[Density / (20 °C, g / cm 3 )]]> 0.9312 To be tested To be tested

[0057] Example 1: The density of heavy oil A was determined at 20℃±0.1℃, and parallel samples (1#, 2#) were tested.

[0058] (1) The metal container is washed, dried and weighed (m1) to an accuracy of 0.01g. The temperature t1 is 20℃±0.1℃.

[0059] like Figure 1 As shown, the lower end of the metal cylinder is tightly connected to the heating unit by threads, and the upper end of the metal cylinder is tightly connected to the condenser pipe joint of the storage tank by threads. The outer wall of the metal cylinder is wrapped with an insulation unit. Then, n-heptane in the storage tank is transported to the heating unit, and the n-heptane is heated to clean the metal cylinder (the heating and cleaning temperature is 100℃). The cleaned n-heptane is condensed and returned to the storage tank.

[0060] (2) Measurement of water content in a metal container at temperature t1

[0061] The sealed metal cylinder is completely immersed in a constant temperature water bath at temperature t1. After maintaining the temperature for 1 hour, the upper cylinder is unscrewed, filled with water at temperature t1, and the cylinder is screwed back on. After removing it, the surface water is wiped off with a towel, and the total mass (m2) of the metal cylinder, water, and cylinder support at that temperature is measured.

[0062] At temperature t1, the mass of water in the metal cylinder is m2-m1.

[0063] (3) Sample testing

[0064] Heavy oil sample A, which is non-flowable at temperature t1, is heated to 47°C. Approximately 200g of the heavy oil (about 80% of the container's volume) is carefully poured into a metal cylinder using a metal funnel. The metal container containing sample A is then sealed and placed back into the original heating oven. Heating continues for 1 hour. The power is then turned off, and the metal container containing sample A is left in the oven to cool to room temperature before being weighed (m³). From the time the heavy oil sample A is poured into the container until cooling and the completion of the test, stirring of sample A is prohibited.

[0065] (4) Place the metal container containing sample A into a constant temperature water bath at temperature t1. The metal container should be completely submerged in water, with the water level 10 mm above the top of the metal cylinder. After maintaining the temperature for 2 hours, unscrew the upper cylinder support, fill it with water at temperature t1, screw the cylinder support back on, wipe the surface water clean with a towel, and weigh the total mass (m4) of heavy oil sample A, metal cylinder, water, and cylinder support. See Table 2 for specific values.

[0066] After weighing, clean the metal cylinder for later use: After weighing, unscrew the upper cylinder support of the metal cylinder, pour out the water, and then place it on the cleaning device. First, set the column insulation temperature to 47℃ for a period of time, then the heavy oil flows into the container of the heating unit and flows out through the bottom valve. Open the valve connecting the top storage tank of the tower, inject n-heptane into the reactor, connect the other end of the metal cylinder to the condenser pipe joint, turn on the heating unit, and clean the metal cylinder. The cylinder support is placed in a container containing n-heptane for heating and cleaning.

[0067] (5) Calculation of results

[0068] The density of heavy oil is calculated using the following formula: ρ = ρ w ×(m3-m1) / [(m2-m1)-(m4-m3)]

[0069] In the formula, ρ: the density of the heavy oil to be tested at temperature t1 (g / m³) 3 m1: Mass of the metal cylinder and upper and lower supports (g); m2: Total mass of the metal cylinder, water, and upper and lower supports (g); m3: Total mass of the metal cylinder, upper and lower supports, and heavy oil (g); m4: Total mass of heavy oil, metal cylinder, upper and lower supports, and water (g); ρ w Density of water at temperature t1 (g / m³) 3 The density of water at 20℃ is 0.9982 g / cm³. 3 .

[0070] Table 2. Results of density determination of heavy oil A at 20℃

[0071]

[0072] Example 2

[0073] The density of heavy oil B at 20℃±0.1℃ was determined, and parallel samples (3# and 4#) were tested.

[0074] (1) The metal cylinder is washed, dried and weighed (m1) to an accuracy of 0.01g. The temperature t1 is 20℃±0.1℃.

[0075] like Figure 1 As shown, the lower end of the metal cylinder is tightly connected to the heating unit by threads, and the upper end of the metal cylinder is tightly connected to the condenser pipe joint of the storage tank by threads. The outer wall of the metal cylinder is wrapped with an insulation unit. Then, the petroleum naphtha in the storage tank is transported to the heating unit, and the petroleum naphtha is heated to clean the metal cylinder (the heating and cleaning temperature is 110℃). The cleaned petroleum naphtha is condensed and returned to the storage tank.

[0076] (2) Measurement of water content in a metal container at temperature t1

[0077] The sealed metal cylinder is completely immersed in a constant temperature water bath at temperature t1. After maintaining the temperature for 1 hour, the upper cylinder is unscrewed, filled with water at temperature t1, and then the upper cylinder is screwed back on. The cylinder is then removed, the surface water is wiped off with a towel, and the total mass (m2) of the metal cylinder, water, and cylinder support at that temperature is measured.

[0078] At temperature t1, the mass of water in the metal cylinder is m2-m1.

[0079] (3) Sample testing

[0080] Heavy oil sample B, which is non-flowable at t1, is heated to 87°C. Approximately 200g of sample B (about 80% of the container's volume) is carefully poured into a metal cylinder using a metal funnel. The container containing sample B is then placed back into the original heating oven and heated for another hour. The power is then turned off, and the container remains in the oven to cool to room temperature before being weighed (m³). From the moment sample B is poured into the cylinder until cooling and the completion of the test, stirring of sample B is prohibited.

[0081] (4) Place the metal cylinder containing sample B into a constant temperature water bath at temperature t1, ensuring the entire metal cylinder is submerged in water with the water level at least 10 mm above the top of the cylinder. After maintaining the temperature for 2 hours, unscrew the upper cylinder support, fill the cylinder with water at temperature t1, screw the cylinder support back on, and wipe the surface water clean with a towel. Weigh the total mass (m4) of heavy oil sample B, the metal cylinder, the water, and the cylinder support. See Table 3 for specific values.

[0082] After weighing, clean the metal cylinder for later use: After weighing, unscrew the upper cylinder support of the heavy oil metal cylinder, pour out the water, and place it on the cleaning device. First, set the column insulation temperature to 87℃ for a period of time, then the heavy oil flows into the distillation kettle and flows out through the bottom valve. Open the valve connecting the top storage tank of the column, inject a certain amount of naphtha into the kettle, connect the other end of the metal cylinder to the condenser pipe joint, turn on the heating unit, and clean the metal cylinder. The cylinder support is placed in a container containing naphtha for heating and cleaning.

[0083] (5) Calculation of results

[0084] Calculate the density of heavy oil using the following formula:

[0085] ρ=ρ w ×(m3-m1) / [(m2-m1)-(m4-m3)]

[0086] In the formula, ρ: the density of the heavy oil to be tested at temperature t1 (g / m³) 3 m1: Mass of the metal cylinder and upper and lower supports (g); m2: Total mass of the metal cylinder, water, and upper and lower supports (g); m3: Total mass of the metal cylinder, upper and lower supports, and heavy oil (g); m4: Total mass of heavy oil, metal cylinder, upper and lower supports, and water (g); ρ w Density of water at temperature t1 (g / m³) 3 The density of water at 20℃ is 0.9982 g / cm³. 3 .

[0087] Table 3. Results of density determination of heavy oil B at 20℃

[0088]

[0089] Comparative Example 1:

[0090] The density of heavy oil A was tested using the hydrometer method (petroleum hydrometer).

[0091] Heavy oil A was heated to a fluid state at 30℃, and an equal volume of diesel oil was added and mixed. The density of the mixture at 30℃ was measured using a petroleum densitometer according to GB / T 1884 (0.9051 g / cm³). 3 It is known that the density of diesel oil at 20℃ and 30℃ is 0.8715 g / cm³. 3 and 0.8648 g / cm 3 Then, the density of heavy oil A at 20℃ was calculated by referring to the table in GB / T 1885 Petroleum Measurement Tables. The results are shown in Table 4.

[0092] Table 4. Results of density determination of heavy oil at 20℃ using the A-meter method

[0093]

[0094] Comparative Example 2:

[0095] The temperature was measured at 70℃ using a hydrometer and then converted to 20℃.

[0096] The density of heavy oil B was tested using a hydrometer method (petroleum hydrometer). Heavy oil B was heated to a fluid state at 70℃, and an equal volume of diesel oil was added and mixed. The density of the mixture at 70℃ was first determined using a petroleum hydrometer according to GB / T 1884 (0.8855 g / cm³). 3 It is known that the density of diesel oil at 20℃ and 70℃ is 0.8715 g / cm³. 3 and 0.8380 g / cm 3 Then, the density of heavy oil B at 20℃ was calculated by referring to the table in GB / T1885 Petroleum Measurement Tables, and the results are shown in Table 5.

[0097] Table 5. Results of density determination of heavy oil at 20℃ using the B-type hydrometer method.

[0098] project diesel fuel Heavy oil B Equal volume mixed oil <![CDATA[Density / (70 °C, g / cm 3 )]]> 0.8380 0.9330 0.8855 <![CDATA[Density / (20 °C, g / cm 3 )]]> 0.8715 0.9662 —

[0099] Comparing the test results in Tables 2-5, it can be seen that the density determination results of heavy oil A and heavy oil B obtained by the test method provided by this invention and the hydrometer method differ significantly.

[0100] Test result verification:

[0101] The following complete distillation experiments of heavy oil A and heavy oil B were conducted according to GB / T 17280 and GB / T 17475, with each fraction at 20℃. The yield and density of the narrow distillate fractions of heavy oil A and heavy oil B at their true boiling points were calculated using the following formula: Heavy oil density balance value = Σ(density of distillate fraction × yield of distillate fraction). The obtained heavy oil density balance value was then compared with the measured value. The results are shown in Tables 6 and 7.

[0102] Table 6. Comparison of density measurement results for heavy oil A

[0103]

[0104] The densities of each fraction from the initial distillation to 350℃ in Table 6 are measured values ​​using a hydrometer at 20℃. The two densities of the fraction above 350℃ are 0.9312 g / cm³. 3 The density of the crude oil (measured by a hydrometer) is 0.9756 g / cm³. 3 The density of heavy oil A at 20°C, as measured in Example 1, is 0.9514 g / cm³. 3 The density of heavy oil A at 20℃ was measured for Comparative Example 1. 0.9339 g / cm³ 3The crude oil density balance value is based on Example 1, and 0.9165 is based on Comparative Example 1. After calculation, the relative deviations of the density test results of Example 1 and Comparative Example 1 are 0.0027 and 0.0147, respectively. It can be seen that the crude oil density balance value obtained based on the test method of Example 1 is better than the crude oil density balance value obtained based on Comparative Example 1, and the test results obtained by the test method of Example 1 are more accurate.

[0105] Table 7. Comparison of Heavy Oil B Density Measurement Results

[0106]

[0107] Table 7 shows the densities of each fraction from the initial distillation to 350℃, all measured values ​​using a hydrometer at 20℃. Densities above 395℃ are measured values ​​obtained after heating using a hydrometer at the corresponding temperatures, then converted to 20℃. The two densities of the >540℃ fraction are both 1.0051 g / cm³. 3 The density of heavy oil B at 20°C, as measured in Example 2, is 0.9962 g / cm³. 3 The density of heavy oil B at 20℃ was measured for Comparative Example 2. 0.9339 g / cm³ 3 The crude oil density balance value obtained from Example 2 is 0.9180 g / cm³. 3 The crude oil density balance values ​​obtained from Comparative Example 2 are 0.0027 and 0.0132, respectively. It can be seen that the crude oil density balance values ​​obtained from Example 2 are better than those obtained from Comparative Example 2, and the test results of Example 2 are more accurate.

Claims

1. A method for testing the density of heavy oil, comprising the steps of filling a cleaned metal container with heavy oil and then testing the density of the heavy oil by weighing, wherein the cleaning device for cleaning the metal container includes a heating unit, a heat preservation unit and a storage tank, wherein the heating unit is used to heat the cleaning solvent to clean the metal container, the heat preservation unit is used to keep the metal container warm during the cleaning process, and the storage tank is used to provide the cleaning solvent and collect the cleaning solvent after cleaning.

2. The method for testing the density of heavy oil according to claim 1, characterized in that, The metal container includes a metal cylinder and a support, with the two ends of the metal cylinder and the support tightly connected by threads to form a sealed metal container.

3. The method for testing the density of heavy oil according to claim 2, characterized in that, Specifically, the following steps are included: (1) After cleaning and drying the metal container, the first weighing is performed to obtain m1. (2) After the metal container is kept at a constant temperature in a constant temperature water bath at temperature t1, the metal container is filled with water at temperature t1 and weighed a second time to obtain m2. (3) After heating the heavy oil to be tested to a fluid state, add the heavy oil sample to the metal container using a metal funnel, and weigh it a third time after cooling to obtain m3. (4) After placing the metal container containing the heavy oil sample to be tested in step (3) in a constant temperature water bath at temperature t1, fill the metal container containing the heavy oil to be tested with water at temperature t1 and weigh it for the fourth time to obtain m4. (5) Calculate the density ρ of the heavy oil sample to be tested according to the following formula: ρ=ρ w ×(m3-m1) / [(m2-m1)-(m4-m3)] In the formula, ρ: density of the heavy oil to be tested at temperature t1, g / m³ 3 ;ρ w Density of water at temperature t1, in g / m³ 3 .

4. The method for testing the density of heavy oil according to claim 3, characterized in that, In step (1): The cleaning solvent used is an oil with a final boiling point of less than 200°C from Engel distillation, preferably at least one of naphtha, petroleum ether, and n-heptane; and / or, The drying temperature after cleaning is 80–140°C, preferably 100–110°C.

5. The method for testing the density of heavy oil according to claim 3, characterized in that, The cleaning in step (1) includes: tightly connecting the lower end of the metal cylinder to the heating unit, tightly connecting the upper end of the metal cylinder to the condenser pipe joint of the storage tank through threads, and wrapping the outer wall of the metal cylinder with an insulation unit; then the cleaning solvent in the storage tank is transported to the heating unit, the cleaning solvent is heated to clean the metal cylinder, and the cleaning solvent after cleaning is condensed and returned to the storage tank. The cleaning in step (1) also includes the step of cleaning the cylinder support by heating with a cleaning solvent; Preferably, the temperature for heating and cleaning is 90–150°C.

6. The method for testing the density of heavy oil according to claim 3, characterized in that, In step (2), the temperature t1 of the constant temperature water bath is 15-20℃; and / or, The constant temperature water bath time in step (2) shall be no less than 1 hour, preferably 1 to 2 hours; and / or, Step (2) also includes the steps of weighing, emptying the metal container, and drying it.

7. The method for testing the density of heavy oil according to claim 3, characterized in that, In step (3), the conditions for heating the heavy oil to be tested are: the heating temperature does not exceed 25°C above the pour point of the heavy oil to be tested; and / or, In step (3), the volume of the heavy oil sample to be tested added to the metal container is 70-90% of the total volume of the metal container, preferably 75-85%.

8. The method for testing the density of heavy oil according to claim 3, characterized in that, The temperature t1 of the constant temperature water bath in steps (4) and (2) is the same; and / or, The constant temperature water bath time in step (4) shall be no less than 2 hours, preferably 2 to 3 hours.

9. The method for testing the density of heavy oil according to any one of claims 1 to 8, characterized in that, The metal container is made of stainless steel.

10. A method for testing the density of heavy oil according to any one of claims 1 to 9, used for testing the density of oil products with an initial boiling point greater than 350°C using Engel distillation.

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