GB/T 3392-2003 Determination of hydrocarbon impurities in industrial propylene - Gas chromatography
Some standard content:
GB/T3392--2003
This standard is modified by adopting ASTMD2712:1991 (1996) "Standard Test Method for Trace Hydrocarbons in Propylene Concentrate by Gas Chromatography" (English version), and GB/T3392--1991 "Determination of Hydrocarbon Impurities in Industrial Propylene by Gas Chromatography" is revised. This standard is modified when adopting ASTMD2712:1991 (1996). The main differences between this standard and ASTMD2712:1991 (1996) are:
-The chromatographic column is changed from a packed column to an Ai.O:PLOT capillary column. - The calibration area normalization method is added to the quantitative method. - The self-determined repeatability (r) is adopted. For the convenience of use, this standard has also been appropriately modified in editing. Appendix A lists the comparison table of the chapter and article numbers of this standard and the chapter and article numbers of ASTML2712:1991 (1996). This standard replaces GB/T3392-1991 "Determination of hydrocarbon impurities in industrial propylene by gas chromatography". The main changes of this standard compared with GB/T3392-1991 are as follows: The packed column of the original standard is replaced by AI2O:PLOT capillary column. The injection method specifies the technical requirements for the complete vaporization of a small amount of liquid sample, and adds direct liquid injection using a liquid injection valve.
The method of certain amount adds the correction area normalization method. Appendix A of this standard is an informative appendix.
This standard is proposed by China Petrochemical Corporation. This standard is under the jurisdiction of the Petrochemical Subcommittee of the National Technical Committee for Chemical Standardization (SAC/TC63/SC4). The drafting unit of this standard: Refining and Chemical Department of Shanghai Petrochemical Corporation. The main drafters of this standard: Ge Zhenxiang, Cao Mingji, Cai Weixing. The previous versions of the standards replaced by this standard are: GB/T 3392--1982, GB/T 3392--1991. 1 Scope
Determination of hydrocarbon impurities in industrial propylene
Gas chromatography
GB/T3392-2003
1.1 This standard specifies the method for determining hydrocarbon impurities such as methane, ethane, ethylene, propane, cycloalkane, isobutane, n-butane, diene, acetylene, trans-2-butene, 1-butene, isobutylene, cis-2-butene, 1,3-butadiene, methylacetylene, etc. in industrial propylene with a volume fraction of not less than 0.0002% by gas chromatography. The volume fraction of propylene can be obtained by subtracting the total amount of impurities from 100.00%. Since this standard cannot determine all possible impurities, such as hydrogen, oxygen, carbon monoxide, carbon dioxide, water, polymers and alcohol compounds, other test methods are required to fully characterize propylene samples. 1.2 This standard is not intended to address all safety issues associated with its use. Therefore, users of this standard should establish appropriate safety and protection measures and determine appropriate management systems in advance. 2 Normative references
The provisions in the following documents become provisions of this standard through reference in this standard. For any dated referenced document, all subsequent amendments (excluding errata) or revisions are not applicable to this standard. However, parties to an agreement based on this standard are encouraged to study whether the latest versions of these documents can be used. For any undated referenced document, the latest version applies to this standard. GB/T3393-1993 Determination of trace hydrogen in industrial ethylene and propylene by gas chromatography GB/T3394-1993 Determination of trace carbon monoxide and carbon dioxide in industrial ethylene and propylene by gas chromatography
GB/T3396-2002 Determination of trace oxygen in industrial ethylene and propylene by electrochemical method GB/T 3723-1999
General safety rules for sampling of industrial chemical products (idtISO3165:1976) GB/T3727-2003 Determination of trace water in industrial ethylene and propylene GB/T 8170-1987
Rules for rounding off values
GB/T 9722-19881
General rules for gas chromatography of chemical reagents
GB/T 12701-1990
Determination of trace methanol in industrial ethylene and propylene Gas chromatography GB/T 13290—1991
Liquid sampling method for industrial propylene and butadiene GB/T19186—2003 Determination of oligomer content in industrial propylene Gas chromatography 3 Method Summary
3.1 Correction area normalization method
Under the conditions specified in this standard, inject an appropriate amount of sample into the chromatograph for analysis. Measure the peak area of each impurity and main component, and calculate the volume fraction of each component by the correction area normalization method. Impurities such as hydrogen, oxygen, carbon monoxide, carbon dioxide, water, oligomers and alcohol compounds are determined by the corresponding standard methods, and the results obtained are normalized with the results of this standard. 3.2 External standard method
Under the conditions specified in this standard, inject the sample to be tested and the external standard into the chromatograph for analysis. Determine the peak area of each impurity and external standard in the sample, and calculate the content of each impurity from the ratio of the peak area of the impurity in the sample to the peak area of the external standard. The propylene concentration can be obtained by subtracting the total amount of hydrocarbon impurities and the total amount of impurities such as hydrogen, oxygen, carbon monoxide, carbon dioxide, water, oligomers and alcohol compounds determined by other standard methods from 100.00%.
4 Reagents and materials
4.1 Ammonia
Carrier gas, gas purity ≥ 99.99% (volume fraction). GB/T 3392--2003
4.2 Ammonia
Carrier gas or make-up gas, gas purity ≥ 99.99% (volume fraction). 4.3 Standard reagents
The required standard reagents are the various hydrocarbons described in 1.1, which are used for determining the correction factor and preparing the external standard sample, and their mass fraction should not be less than 99%.
5 Instruments
5.1 Gas Chromatograph
Gas chromatograph with programmed temperature function and equipped with flame ionization detector (FID). The peak height produced by the instrument for the impurity with the lowest concentration specified in this standard shall be at least twice the instrument noise. Moreover, when the normalization method is used to analyze the sample, the dynamic linear range of the instrument must meet the requirements.
The gas chromatograph should have a sufficient range of linear programmed temperature operation function to meet the requirements of chromatographic separation. During the entire analysis process, the programmed temperature rate should have sufficient reproducibility so that the retention time can reach a repeatability of 0.05min (3s). 5.2 Chromatographic Column
The chromatographic columns and typical operating conditions recommended in this standard are shown in Table 1, and the typical chromatogram is shown in Figure 1. The peak order and relative retention time of impurities depend on the deactivation method of the AI,O:PLOT column, and must be verified with standard samples when used. Other chromatographic columns that can achieve the same separation efficiency may also be used.
Table 1 Chromatographic columns and typical operating conditions
Chromatographic column
Column length/m
Column inner diameter/mm
Average linear velocity of carrier gas/（cm/s）
Injector temperature/℃
Detector temperature/℃
Split ratio
Injection volume
Initial temperature/℃
Initial temperature holding time/min
First stage heating rate/(℃/min）
First stage final temperature/℃
First stage final temperature holding time/min
Second stage heating rate/（℃/min）
Second stage final temperature/℃
Second stage final temperature holding time/min
Note: The heating of AlO,PLOT column cannot exceed 200℃ to prevent changes in column activity. 5.3 Injection device
5.3.1 Liquid injection valve (quantitative tube volume 1μl) or other suitable liquid injection device. Al2O, PLOT column
35(N2);41(He)
Liquid 1μL, gas 0.5mL
Any liquid injection valve that meets the following requirements can be used: Propylene can be repeatedly injected in liquid state at a propylene vapor pressure not lower than the operating temperature, and meet the requirements of chromatographic separation. The flow diagram of the liquid injection device is shown in Figure 2. The pore size of the stainless steel sintered sand core in the metal filter is required to be 2μm~4um to filter out mechanical impurities that may exist in the sample and protect the injection valve. A stainless steel capillary (or pressure reducing valve) of appropriate length is installed at the outlet of the injection valve to avoid sample vaporization, distortion, and affect injection repeatability. When injecting, open the outlet valve of the sampling cylinder, flush the fixed 2
volume tube with liquid sample for a few seconds, then operate the injection valve, inject the sample into the chromatograph, and then close the outlet valve of the cylinder. 4
methane;
ethane,
ethylene;
4--propane;
cyclopropane;
propylene,
isobutane;
n-butane;
propadiene,
acetylene,
trans-2-butene;
n-butene,
13----isobutene;
-cis-2-butene;
15——1,3-butadiene,
16——methylacetylene.
Sampling cylinder
Figure 1 Typical chromatogram
Metal filter
Capillary
Liquid injection valve
Figure 2 Flow chart of liquid injection device
5.3.2 Gas injection valve (quantitative tube volume is 0.5mL)-venting
GB/T3392—2003
Gas injection uses the small amount of liquid sample vaporization device shown in Figure 3 to completely vaporize the sample and ensure the representativeness of the sample. First, remove the injection cylinder with a volume of about 1700mL at E and evacuate it (<0.3kPa). Then close valve B, open valves C and D, and then slowly open valve B to control the liquid sample to flow into the pipeline cylinder. When a stable liquid sample overflows from valve B, immediately close valves B, C and D in sequence, and a small amount of liquid sample is obtained from the pipeline cylinder. Connect the vacuumed sampling cylinder to E, open valve A first, then open valve B, so that the liquid sample is completely vaporized in the sampling cylinder. At this time, the vacuum pressure gauge connected to the sampling cylinder should indicate a range of (50-100) kPa. Finally, close valve A, remove the sampling cylinder, and connect it to the gas injection valve of the chromatograph, and then the measurement can be carried out. Note: The sampling cylinder containing the liquid sample should be placed in the laboratory for a sufficient time to allow the temperature of the liquid sample to reach equilibrium with the room temperature before performing the above operation. After a small amount of liquid sample is obtained from the pipeline cylinder, the vaporization operation should be completed as soon as possible to avoid the possibility of the pipeline cylinder filled with liquid sample bursting as the residence time increases.
Vacuum pressure gauge
Stainless steel injection cylinder
Volume is about 1700mL
Sampling cylinder
Iron stand
Stainless steel pipeline cylinder
(outer diameter 8mm, wall thickness 1.4mm, length 400mm)HL
Figure 3 Schematic diagram of the vaporization device for small amount of liquid sample5.4 Recording device
Any integrator or chromatographic data acquisition system that can meet the measurement requirements can be used. 6 Sampling
Samples shall be collected according to the safety and technical requirements specified in GB/T3723-1999 and GB/T13290-1991. 7 Measurement steps
7.1 Correction area normalization methodWww.bzxZ.net
7.1.1 Setting operating conditions
Install and age the chromatographic column in the chromatograph according to the instrument operating manual. Then adjust the instrument to the operating conditions shown in Table 1, and start the measurement after the instrument stabilizes.
7.1.2 Determination of correction factor
a) Preparation of standard samples
GB/T3392—2003
Liquid standard samples with known hydrocarbon impurity content can be purchased from the market or prepared by the weight method. The content of hydrocarbon impurities in the standard sample should be similar to that of the sample to be tested. The steel cylinder containing the standard sample should meet the technical requirements of GB/T13290-1991. The propylene background sample used in the preparation should be checked in advance under the conditions specified in this standard. No other hydrocarbon impurities should flow out at the component to be measured, otherwise it should be corrected.
b) According to the requirements specified in 8.1 of GB/T9722-1988, the above-mentioned mixed standard sample is used for measurement under the conditions recommended in this standard, and its corresponding correction factor is calculated.
7.1.3 Sample determination
Use a sample injection device that meets the requirements of 5.3 to inject an appropriate amount of sample into the chromatograph and measure the chromatographic peak area of each component. 7.1.4 Calculation
Calculate the volume fraction of each impurity and propylene by the correction area normalization method, and normalize the result with the total amount of impurities such as hydrogen, oxygen, carbon monoxide, carbon dioxide, water, oligomers and alcohol compounds determined by other standard methods (see normative reference documents). Calculate the volume fraction of each hydrocarbon impurity or propylene according to formula (1). AXR
X(100.00-Φ）
(A, × R,)
Where:
Φ,—volume fraction of impurity i or propylene in the sample, %; A—peak area of impurity i or propylene in the sample; R,—correction factor for impurity i or propylene; Φ is the total volume fraction of impurities obtained by other methods, %. 7.2 External standard method
....( 1 )
7.2.1 After the instrument is stable according to 7.1.1, use the sample injection device that meets the requirements of 5.3 to inject the same volume of the sample to be tested and the standard sample into the chromatograph respectively, and measure the peak areas of all hydrocarbon impurities and external standards except propylene. The difference between the peak areas of the standard sample measured twice should not be greater than 5% of the average value, and the average value is taken for quantitative calculation. 7.2.2 Calculation
7.2.2.1 Calculate the external standard quantitative correction factor of each component in the standard sample according to formula (2). fi = c,÷A,
Where:
f.—-External standard quantitative correction factor of component i; -Concentration of component i in the standard sample, % (volume fraction); c.
A,—Peak area of component i in the standard sample.
7.2.2.2 Calculate the volume fraction of each hydrocarbon impurity component in the sample according to formula (3), %. $=f×A;
++***+(2)
7.2.2.3 Accumulate the content of each hydrocarbon impurity component to obtain the total amount of hydrocarbon impurities. The volume fraction of propylene can be obtained by subtracting the total amount of hydrocarbon impurities and the total amount of impurities such as hydrogen (GB/T3393--1993), oxygen (GB/T3396-2002), carbon monoxide and carbon dioxide (GB/T3394-1993), water (GB/T3727--2003), polymers (GB/T19186-2003) and alcohol compounds (GB/T12701-1990) determined by other standard methods from 100.00%. 8.1 For any sample, the numerical rounding of the analysis result shall be carried out in accordance with the provisions of GB/T8170-1987, and the analysis result shall be expressed as the arithmetic mean of the results of two repeated measurements.
8.2 The volume fraction of each hydrocarbon impurity shall be reported with an accuracy of 0.0001%. 9 Precision
9.1 Repeatability
GB/T 3392-2003
In the same laboratory, by the same operator, using the same instrument, the same sample is measured twice in succession. Under the condition of 95% confidence level, the difference between the results should not be greater than the following values: Impurity component content
≤0.0010% (volume fraction)
>0.0010% (volume fraction)～≤0.010% (volume fraction)>0.010% (volume fraction)
The report should include the following:
30% of its average value
20% of its average value
10% of its average value
All information about the sample , such as sample name, batch number, sampling location, sampling date, sampling time, etc.; a)
b) This standard code;
Analysis results;
Details and explanations of any abnormal phenomena observed during the measurement; d)
Name of the analyst and the date of analysis, etc.
Appendix A
(Informative Appendix)
Comparison between the chapter and article numbers of this standard and the chapter and article numbers of ASTMD2712:1991 (1996) GB/T3392—2003
Table A.1 gives a comparison table between the chapter and article numbers of this standard and the chapter and article numbers of ASTMD2712:1991 (1996). Table A.1Comparison of the chapter numbers of this standard with those of ASTM D2712:1991 (1996) Chapter numbers of this standard
5.1 and 5.4
Corresponding chapter numbers of ASTM standards
3.1 and 3.2
10 and 11
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