SY/T 0545-1995 Determination of thermal characteristics of wax precipitation in crude oil - Differential scanning calorimetry SY/T0545-1995 Standard download decompression password: www.bzxz.net

Petroleum and Natural Gas Industry Standard of the People's Republic of China SY T 0545-1995
Determination of Thermal Characteristics Parameters of Waxing of Crude Oil
Differential Scanning Calorimetry
1995--12-18 Issued
China National Petroleum Corporation
Implementation on 1996-06-01
Citations
Definitions and Symbols
Instruments and Materials
Test Procedures
Explanation of Results
This standard is proposed based on the technical problems encountered in the process of crude oil gathering and transportation, and is included in the industry standard formulation plan of Runtian Natural Gas Corporation: After searching for domestic and foreign standards and conducting research, it was found that there are international standards, foreign advanced standards and equivalent domestic standards that can be adopted in an equivalent or non-equivalent manner. This standard is formulated on the basis of scientific evaluation! , and the quality assurance standards made after verification and testing by the manufacturer can make the determination method of thermal characteristic parameters of crude oil wax precipitation unified and standardized, and make the results obtained by different experiments have the same accuracy. The implementation of this standard is due to the promotion of this method. During the period of this standard, a professional standardization committee for oil and gas field pipeline construction was established. This standard was put forward by the Planning and Design Institute of China National Natural Gas Corporation. The responsible unit for this standard is China Petroleum Pipeline Science Research Institute. The main drafter of this standard is Beijing Quanzhong, Ao Chengzhao, Petroleum and Natural Gas Industry Standard of the People's Republic of China Determination of Thermal Characteristic Parameters of Crude Oil Waxing
Differential Scanning Calorimetry
SY/ 0545—1995
When the components contained in crude oil decrease in density during transportation, they will stick out from the crude oil and accumulate in the oil. This process is generally called crude oil condensation. People have come to realize that crude oil condensation and wax precipitation have important significance for the technical design and scientific research of crude oil storage and transportation. Therefore, a series of thermal properties of crude oil condensation and wax precipitation are necessary. It is known from experimental research that any crude oil condensation follows a common law: it is a process of gradual density change accompanied by thermal effects. For crude oil, the natural characteristic parameters of the analysis are not the same: they are characteristic parameters. In order to quantitatively characterize the research, the characteristic parameters are: fat separation point, wax separation peak temperature, fat separation peak temperature range and wax thermal analysis within a certain temperature. Thermal analysis refers to a mature technology that measures the relationship between the physical properties and temperature under program control. Differential Scunning Calorimetry (Differential Scunning Calorimetry, internationally referred to as DSC) is a method of using energy to determine the best chemical and thermal properties in thermal analysis. Technology, Sichuan Instruments finalized commercialization. In the past year, through experimental research, the method of using DSC to determine the thermal characteristics of crude oil has been mastered: the measured thermal characteristic parameters and thermal analysis of crude oil have been used! In order to guide the production operation and scientific research of crude oil collection, storage and transportation, this standard is formulated in the natural gas industry to unify and standardize this determination method. Under the provisions of this standard, differential scanning calorimetry (DSC) is used to determine the wax point of crude oil, and the peak analysis is as follows: This standard is used to determine the thermal characteristic parameters of wax precipitation, such as the peak leakage area and the compensation heat and cold. It is applicable to the determination of thermal characteristic parameters of wax precipitation of crude oil with a small amount of water (5).
2 Referenced standards
The provisions contained in the underlined standards are incorporated into the provisions of this standard through citation. At the time of publication of this standard, the versions shown are valid. All standards are subject to revision. The parties using this standard shall discuss the possibility of using the latest version of the standard. GB/T 253888 Original test method
GB/475684 Sampling method for products of thermal analysis and liquid petroleum (manual method) GBT 6425-86 Thermal analysis method
ASTM F967 ..92 Temperature Calibration of Differential Scanning Calorimeter and Differential Thermal Analyzers ASTM E96887 Heat Flow Calibration of Differential Scanning Calorimeter Heat flow calibration of differential scanning calorimeter
3 Definitions and symbols
This standard adopts the following definitions and symbols (the terms related to thermal analysis technology are in accordance with the definitions of thermal analysis terms in GB/T 6425). 3.1 Wax Priscipltation Point The temperature at which the sample just begins to precipitate from the liquid system, that is, the starting temperature at which the DSC curve of the sample slowly begins to deviate from the baseline to form an exothermic response. 3.2 The heat release rate of the oil in the oil is the true temperature of the oil line thermal peak to the temperature of the oil line, and the heat released by the wax sample in the wax recipe from 7 to 1 degree K ... Precipilalmn a range: the sample temperature is reduced by 1 (the original heat released before): this reaches or exceeds the minimum temperature of the sample in the temperature range of 20℃~T
4 Principle
The crude oil sample is heated to the wax point temperature on a differential scanning calorimeter (DSC instrument): then the differential heat flow (or power difference) of the reference material at each temperature point is recorded at a constant speed. The differential heat flow (or power difference) is used as the ordinate and the temperature is used as the horizontal axis to finally draw the wax precipitation differential calorimetry curve (DSC curve). When the temperature is cooled through the wax precipitation zone, the heat released by the wax precipitation causes a change in the differential heat flow (or power difference), which is manifested on the DSC curve as an exothermic peak that deviates from the baseline. As the temperature continues to decrease, the heat released by the wax precipitation gradually decreases, and the differential heat flow (or power difference) decreases accordingly. Finally, the curve returns to the baseline: the precipitation process is over. ：The temperature at which the curve starts to deviate from the baseline is the original wax point: The peak temperature of the curve is the original peak temperature: According to the heat release and mass of the sample between T and -20℃, calculate the wax precipitation calorimetry of crude oil A15 Instruments and Materials
5.1 DSC calorimeter
Measurement range: -35-~90℃3
Controllable cooling speed: (5o.5)min: Sufficient sensitivity or minimum range: ±4.18ml/s or 6w/cm. The instrument should be calibrated according to ASTME967, ASTME968 or the method and standard materials provided by the instrument manufacturer. 5.2 Analytical balance
Its sensitivity is 0.1mg
5.3 Sample dish
is a special LDSC sample dish with positive: III bottom is flat and without deformation 5.4 CoolantWww.bzxZ.net
is dry ice, liquid nitrogen, or cooling with refrigeration equipment 6 Test steps
6.1 Specimen preparation
6.1.1 Obtain the sample according to B:T4756. Its water content should be more than 0.59. Otherwise, it will become qualified according to 3.3.2 of B/T253868.
6.1.2 Take about 20g of sample from the upper, middle and lower parts of the sample container and place it in a 50ml beaker. Stir it evenly in a water grid (one stream is 50℃). Take it out and continue to stir and cool it to room temperature. 6.2 Test procedure
6.2.1 Weigh 4-81g of sample with a sample weight of 0.1: 0.6.2.2 Set up the DSC instrument and heat the DSC detection cell to the initial test temperature, usually 755℃, that is, the expected precipitation point of the weak sample is 20-25℃.
6.2.3 Place the sample III containing the test material in the DSC test cell. When selecting the sample support (i.e., the sample as the reference material), place the sample and the reference material in the center of their respective supports to ensure sufficient thermal contact between the supports. Cover with a cooling hood,
SY/ T 0545-1995
6.2.4 Keep constant humidity for 0.5 to 1 min, cool to 1; then cool to the end temperature at a rate of 5°C/min, usually -30--35°C, and perform continuous scanning from the initial temperature to the end temperature: record the DSC results.
7.1 Result
On the DSC line:
Find the starting temperature corresponding to the exothermic peak formed when the baseline deviates from the high humidity, which is the following: -Find the corresponding temperature of the exothermic peak perpendicular to the temperature axis, which is 7: Connect the curve points of T and -20°C to make the interpolation baseline of the exothermic peak. Calculate the peak area surrounded by this interpolation baseline and the DSC curve, excluding the cooling rate and the sample mass. The average wax precipitation heat is obtained by dividing A1 by the temperature value included in the sample from T: to -20°C, and the average wax precipitation heat is obtained. Starting from Tc:, measure the heat released by each 1° decrease in the test temperature, and the temperature range corresponding to the temperature reaching or exceeding AH/AT is the wax precipitation peak temperature range.
An example of crude oil wax precipitation DSC curve is shown in Figure 1.
Figure 1 Example of crude oil wax precipitation DSC curve
7 Breaking point, -1--Peak precipitation temperature range, the same peak temperature 1-20℃72
The same operator uses the same instrument in the same laboratory, and repeats the measurement on the same sample in the continuous test according to the steps specified in the method. The difference between the two results of TcTP should not exceed 2℃. When the 4H measurement value is greater than 20℃: the difference between the two results should not exceed 10% of the arithmetic mean value; when the AH measurement value is less than or equal to 20℃, the difference between the two results should not exceed 20% of the arithmetic mean value.
8 Report
The arithmetic mean value of the repeated measurement results shall be adjusted. The relevant temperature values ​​shall be rounded to single digits. The AH value shall be rounded to one decimal place: Report the result.
1 It can include the selection of appropriate coolant and refrigeration equipment,
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