Standard method for determining the true density of calcined petroleum coke by helium gas densitometer - Master's thesis - Dissertation

American ASTM Standard D2638-91 (2002)
Standard method for determining the true density of calcined petroleum coke by helium gas density meter

1. range
1.1 This standard method is used to determine the true density of calcined petroleum coke. By definition, the true density of petroleum coke is the density measured with a sample having a particle size of less than 75 microns (by a resolution 200 mesh test sieve). The results are reported in metric units.
1.2 Density is an important physical property of petroleum products and is an integral part of product specifications.
1.3 The true density of petroleum coke directly affects the physical and chemical purchases of carbon and graphite prepared from it. It is usually based on the density index. If it is based on volume, it can be converted to mass (weight) by density measurement. The basis for trading.
Density, sometimes called relative density, is often referred to as specific gravity. In fact, these terms are strictly different in the following sense:
Density: The mass per unit volume (mass weighed in vacuum) at a temperature of 15 ° C is called the density of the substance in units (Kg/m3, g/cm3).
Relative density: The ratio of the mass of a certain volume to the mass of the same volume of pure water at the same temperature at 15 °C. The relative density has no unit.
Specific gravity: meaning is the same as relative density.

2. references
2.1 ASTM standard
D346 Laboratory sample analysis and preparation method
D2013 Method for analyzing coal sample vegetation
D2234 Coal sampling method
D4057 Manual sampling method for petroleum and petroleum products
D4292 Method for determination of vibration bulk density of calcined petroleum coke
D4930 Experimental method for controlling dust control of petroleum coke
Specifications of E11 wire mesh test sieve

3. the term
3.1 Definition
3.1.1 Calcined petroleum coke - heat treatment of raw (green) petroleum coke to remove volatile matter and form petroleum coke after crystal structure
3.1.2 Petroleum Focus—The carbonaceous residue formed by thermal decomposition of heavy petroleum components or/and petroleum lysates.
3.2 Standard-specific terminology
3.2.1 BULK DENSITY—The mass of the particulate matter divided by the volume occupied by the particulate matter including the space between the particles. The experimental method of bulk density can be found in D4292.
3.2.2 Dust removal materials - see D4930
3.2.3 True Density—The mass of a substance divided by the volume occupied by the substance (excluding voids and pores within the substance) yields the true density of the substance. By grinding the coke particles to a void of less than 75 micrometers to break the coke, the use of helium as a test medium ensures that the gas molecules enter the coke pores, in which case the true volume and true density of the material can be tested.
3.2.3.1 Discussion: The concentration of coke samples larger than 75 microns to greater can also be measured by gas densitometer, but the result must be noted as the particle focal density (PD). The precise data obtained by measuring the true density may be Not applicable to the determination of particle density.

4. Method points
4.1 A representative petroleum coke sample was dried and ground to a 75 micron (200 mesh) test sieve. The mass of the sample is weighed directly with the balance, and the sample is placed in a densitometer, and the volume of the sample is derived based on the helium volume of the sample. The mass to volume ratio of the sample is the true density of the sample.

5. Significance and use of the determination
5.1 The true density of petroleum coke directly affects the physical and chemical properties of the carbon and graphite devices produced using it. Therefore, the true specific gravity is the main quality index of calcined petroleum coke, and the true specific gravity is also the control index of the petroleum coke calcination treatment.

6. interference
6.1 The oil and other substances used for dust control on the calcined petroleum coke back affect the determination of the true specific gravity. Therefore, the oil must be removed before the sample is broken to 75 microns. See D4930 for the method.

7. instrument
7.1 Analytical balance, accurate to ±0.1mg
7.2 Dryer
7.3 The drying oven is preferably vacuum dried and the temperature is controlled to 120 °C.
7.4 æ°¦ Density meter
7.5 Crocodile Crusher and Roller
7.6 Rifflers with hopper and cover.
7.7 Screen sieve: 200 mesh

8. Reagent material
8.1 æ°¦, the purity is too difficult to close 99.9%

9. Sample Preparation
9.1 For the sampling of petroleum coke samples, the recommended method for sample preparation is shown in Experimental Methods D246, D2013, D2234, D4057, D4930. The equipment and procedures used to break and shrink the sample are also described in these standards.
9.2 The crude sample is broken and shredded into laboratory analytical samples.
9.3 Use a reducer to shrink 100G analytical samples from laboratory samples.
Note 1: The instrument operation guide provided by the manufacturer of the æ°¦ density meter specifies the sample quality required for the test. However, in order to ensure that the experimental sample can represent the entire sample, it is desirable to dispense 100G.
9.4 If the sample contains dust-proof oil, the dust-removing oil must be removed before further crushing the sample. See D4093 for the method.
9.5 The 100G experimental sample was crushed all through the identification of a 75 micron (200 mesh) experimental sieve. The broken sample was baked in a dry box at a temperature of 115 C ± 5 ° C to a constant weight (about 8 hours). Put it in a desiccator to cool.

10. Test procedure
10.1 Place 5–150 g (80-90% of the sample cup used). The dried test sample is placed in the sample cup provided by the instrument, and the sample cup containing the sample (accurate to 1 mg) is weighed.
10.2 Place the weighed sample and sample cup into the sample chamber of the densitometer and pump (row) the empty sample chamber.
10.3 Fill the control room of the instrument with helium gas so that the pressure is higher than the sample chamber, and the control room and sample chamber are connected automatically or manually. Test the pressure after balancing the two chambers.
10.4 Calculate the volume of the petroleum coke sample based on the known volume in the control chamber and the sample chamber, the absolute pressure of each chamber before the two chambers and the final equilibrium pressure after the connection.
10.5 Record the sample volume or density as soon as the density reaches equilibrium.
Note 2: This is the general basic step to obtain the final test results. For further operational details, see the instrument manufacturer's instructions.

11. Calculation
11.1 Calculate the true sample density density from formula (1) = M / V (1)
In the formula:
M: sample quality (g)
V: sample volume of helium (cm3)

12. report
12.1 Report the true density calculated by 11,1 and the data is taken to the decimal place.

13. Precision and deviation
The precision of the 13.1 method is based on the statistical processing of the inter-laboratory test results.
13.1.1 Repeatability—The same analyst, on the same instrument, under the same experimental conditions, the same experimental sample, long-term continuous test according to the correct operation, the difference between the experimental results, in 20 times In the test, the number of times over 0.018 was only one (ie 95% probability). Therefore, the regulations:
Repeatability = 0.018 g/cm3
13.1.2 Reproducibility: The difference between the results of two independent tests performed by different laboratories on the same (equivalent) sample in accordance with the method of this standard. Only one time in the 20 comparisons exceeds 0.025 g/cm3. .

14. Keywords calcined petroleum coke, tantalum density meter, true density.