GB/T 17475-1998 Standard test method for distillation of heavy hydrocarbon mixtures (vacuum still distillation)

Summary page. This page is a compiled excerpt/summary of the standard — it is not the full standard text and does not replace it. Verify every value against the official standard and the product certificate before use.

Evidence note: historical study material for the 1998 edition, not the full text of the standard; technical review is pending. The 25-page scan held runs from the foreword to the last clause of Annex F; no cover, figures or clauses from another edition have been added. The original carries doubts about the distillation rate, the Watson K equation and the stage boundaries, and the content below cannot be used directly for operation, calibration, conformity judgement or product applicability claims.

1. Edition identity and evidence boundaries: Original PDF pages 1-2; official version status record. The body number and title are GB/T 17475-1998, approved 1998-08-20 and implemented 1999-01-01. Page 1 of the file held is the foreword and the body starts on page 2; the file name or the OCR alone is not treated as confirmation of the edition. Two official records of the State Administration for Market Regulation list the 1998 edition as withdrawn, and the standards information platform records that it was wholly replaced by GB/T 17475-2020; both belong to the same official service and are not two independent verifications of technical originals. This card studies the 1998 edition, does not switch automatically to the 2020 edition, and does not determine the version specified in a contract or the final applicability. The foreword describes the relationship of adoption with ASTM D5236-95 and the differences in referenced standards, cold trap and density temperature. Only the historical foreword facts are recorded here; no claim of present-day equivalence or interchangeability is made on that basis.

2. Scope: Original PDF page 2, clause 1. The subject is heavy hydrocarbon mixtures with an initial boiling point above 150 °C, including heavy crude oils, petroleum fractions, residues and synthetic oils, using a fully enclosed distillation still with a low-pressure-drop entrainment separator. Cut temperatures use the corresponding atmospheric-equivalent temperature, AET; the original upper limit is 565 °C, and it is also constrained by the heating limit of the sample, so not every sample can reach that temperature. For crude oil distillation with cut points below 400 °C the original refers to GB/T 17280; distillation curves and fraction properties obtained by the two methods are not directly comparable. Apparatus, sample and cutting programme require separate confirmation.

3. Referenced documents and meaning of results: Original PDF pages 2-4, clauses 2-5. It refers to GB/T 1884, 1885, 4756, 9168, 13377 and 17280, covering density, metering, sampling, vacuum distillation and crude oil distillation respectively. The original gives no year for these references; this study card does not guess their applicable year or current status. Evaporation rate describes the quantity of vapour entering the distillation head; distillation rate is the quantity of product collected. The two are not exactly equal because of heat losses. Static holdup is the material adhering to the inner walls of the apparatus after the test; glass and steel stills are treated differently. The results are used to study the yields of fractions over different boiling ranges and to prepare fractions for research; prolonged thermal cracking may alter the properties of the residue, so the results are not automatically applied to bitumen evaluation. The cutting programme must be agreed between the parties before the test.

4. Principle and data chain: Original PDF page 3, clause 4. Distillation is carried out within the absolute pressure range 6.6 to 0.013 kPa (50 to 0.1 mmHg) stated in the original, at the specified rate, with fractions collected in stages. The pressure precision in the method summary differs from that of Table 2; each is retained as originally written and they are not combined into a new equipment set point. At each cut point the vapour temperature, operating pressure and other variables are recorded; the mass yield is obtained from the fraction mass and the total recovered mass. Density is measured, converted to volume at 15 °C or 20 °C, and the volume yield is then calculated, establishing the relationship between AET and yield.

5. Apparatus composition and charge size: Original PDF pages 4-9, clause 6, Table 1 and Figures 1-6. The system comprises the distillation still, a distillation head with entrainment separator, temperature sensor, vacuum measurement, condenser, receiver system, buffer vessel and cold trap. The original distinguishes four sizes by distillation head internal diameter: 25, 36, 50 and 70 mm. The original recommends a loading factor of 200 to 400 mL/cm² and a still at least 50% larger than the charge volume. Stills larger than 10 L are made of stainless steel; volume and material must not be inferred from a product name alone. The upper part of the sensitive end of the vapour sensor sits 3 mm ± 1 mm below the overflow point; the original wording for the 0 °C platinum resistance sensor is 100 Ω, or a sheathed type J thermocouple, with a response below 1 min and a reading accuracy of 0.5 °C. The relationship between the 6 mm thermocouple sheath distance from the still bottom in the text and the 10 mm marked position in Figure 3 still awaits technical verification and is not forcibly unified. The dimension tables of Figures 1-6 retain source-image verification evidence; only the charge table is given here, and no joints, cold traps or manufacturing drawings have been reconstructed. Safety requirements for high temperature and high vacuum, including implosion protection, cooling water and automatic alarms, must be followed in accordance with the formal documents and equipment procedures. | Head internal diameter mm | Neck cross-sectional area cm² | Charge L | Still capacity L | | --- | --- | --- | --- | | 25 | 5 | 1-2 | 2-3 | | 36 | 10 | 2-4 | 3-6 | | 50 | 20 | 4-8 | 6-12 | | 70 | 40 | 8-16 | 12-24 |

6. Pressure and distillation rate: Original PDF page 12, Table 2 and clause 9.9. In the table the evaporation rate is in mL/(h·cm²) and the four distillation rate columns are in mL/h, for head internal diameters of 25, 36, 50 and 70 mm. The original mentions a recommendation to use 80% of the maximum permitted value; this proportion must not be used to alter the original figures in the table. Particular item [to be verified]: for the cell at 1.33 kPa (10 mmHg) with a 36 mm head, the scanned original reads 750-12 500 mL/h; this is retained as written and has not been inferred from area, trend or another edition as 750-1250. Until that doubt is resolved the table must not be used as a direct operating set point. | Operating pressure kPa (mmHg) | Evaporation rate mL/(h·cm²) | Head 25 mL/h | Head 36 mL/h | Head 50 mL/h | Head 70 mL/h | | --- | --- | --- | --- | --- | --- | | 6.67 (50) | 90-150 | 450-750 | 900-1 500 | 1 800-3 000 | 3 600-6 000 | | 1.33 (10) | 75-125 | 375-625 | 750-12 500 | 1 500-2 500 | 3 000-5 000 | | 0.133 (1) | 45-75 | 225-375 | 450-750 | 900-1 500 | 1 800-3 000 | | 0.0400 (0.3) | 30-50 | 150-250 | 300-500 | 600-1 000 | 1 200-2 000 | | 0.0133 (0.1) | 10-20 | 50-100 | 100-200 | 200-400 | 400-800 |

7. Sample receipt and pre-treatment: Original PDF pages 9-10 and 20-21, clause 7 and Annex D. The sampling reference is GB/T 4756, and samples obtained in a GB/T 17280 test may also be used; the receiving container must be closed and leak-free. Samples that wax out or solidify must be brought to a homogeneous liquid before use, and samples containing water are dehydrated first in accordance with Annex D. Annex D covers atmospheric predistillation and combination of the oil samples; nitrogen, cold trap, heating and water/oil separation conditions are an interrelated process, not a recipe that can be applied from the keyword water content alone. Light components must not be lost, and the fraction in the cold trap must not be blended back automatically.

8. Preparation and measurement control: Original PDF page 10, clause 8; pages 6-7 and 17-20. Glass parts are cleaned and dried, and the lubrication and assembly of joints is governed by the formal instrument documents. The weighing basis for receiver tare and sample mass is 0.1% of the charge. The leak check in the original is: evacuate to 0.05 kPa (0.4 mmHg), cut off the vacuum source, and the pressure must not rise by more than 0.01 kPa (0.075 mmHg) in 1 min. The 0.01 kPa and two 2 min checks used for calibration in Annex C are a different procedure and are not interchangeable. The vapour temperature sensor is calibrated on first use and monthly thereafter; the electronic vacuum gauge is verified monthly, with both the reference gauge and the full-range record retained. Accuracy and traceability cannot be demonstrated by powering up, by a stable reading or by the mere existence of a document.

9. Operating logic and stopping conditions: Original PDF pages 10-13, clause 9. The study logic is: confirm density and mass → assemble and stir → controlled heating and pressure reduction → collect cuts as agreed → record → stop and cool → weigh fractions/residue and convert density. This only sets out the process relationships and does not replace a hazardous-operation procedure. In the original the heating rate does not exceed 300 °C/h and the still surface does not exceed 400 °C; some mixtures require a lower surface temperature. The example with an initial boiling point of about 343 °C mentions 0.133 kPa, and this example must not be extended to all heavy oils. If the still liquid reaches 290 °C without reaching the cut end point, the continuation must be assessed; where above 320 °C is expected, the original covers slowing the heating/pressure reduction for 2 to 10 min, restoring 90% of the original heating rate, and not cutting within 2 min of low-pressure stabilization. After 310 °C the original requires reaching the final cut point within 1 h; the run is not continued if the pressure rises or 90% (V/V) has distilled. Automatic vacuum control may mask the pressure rise from cracking, and above 90% (V/V) there is a risk of near-dryness. After termination, heating is stopped and cooling is controlled; unloading the still at 150 °C or forcing out the residue at about 10 kPa are conditions of different equipment and do not authorize on-site operation.

10. Calculation of results and AET equations: Original PDF pages 13 and 21-23, clause 10 and Annex E. The mass recovery consists of the fractions, the residue and, where applicable, the static holdup; the original acceptance range is 99.6% (m/m) to 100.1% (m/m), with the actual loss and its proportion also reported. The volume of each fraction is calculated from its mass and the density at the corresponding temperature; the distillate alone must not be added while ignoring holdup, and volume percentages must not be treated as mass percentages. Equation (E1): AET = 748.1A / [1/(T+273) + 0.3861A − 0.00051606] − 273. T is the observed vapour temperature (°C) and A is the calculation factor. The bracketing of the denominator and the −273 outside the expression are recorded as in the source image. Equation (E2): A = [4.741 − log(P_abs/P_atm)] / [2876.663 − 43.00log(P_abs/P_atm)] − 0.0002867, with the original condition pressure ≤ 0.266 kPa (≤ 2 mmHg). Equation (E3): A = [3.877 − log(P_abs/P_atm)] / [2387.262 − 95.76log(P_abs/P_atm)] − 0.0002867, with the original condition pressure ≥ 0.266 kPa (≥ 2 mmHg). The equality sign appears in both branches, so the choice of boundary remains [to be verified]; the two terms of the pressure ratio must have the same unit, and the base of the logarithm is not stated in that passage. No online calculator is provided. For fractions from 38 to 371 °C the original mentions a Watson K of 12.0 ± 0.2. Equation (E4) scans as K = ∛[1.8(B−273)] / D, where B is in turn defined as the mean boiling point in °C and D is the density at 15 °C; the −273 carries a technical doubt with respect to the temperature-scale definition and is recorded as written, not changed to the usual +273, and the equation from GB/T 17280 is not reused directly. Equation (E5): t = −1.4[K−12][log(P_a/P_o)]. t is the correction value (°C), P_a the atmospheric pressure and P_o the observed pressure (kPa). The nomographs of Figure 7, E1 and E2 used for estimation have not been reconstructed as precise numerical algorithms, and they cannot serve as a direct calculation basis until the doubts are closed.

11. Precision and quality control: Original PDF page 16, clause 12. The table below lists temperature difference limits against the volume percentage of liquid distilled; these are not yield differences or mass percentage errors. Repeatability applies to the same operator and the same apparatus; reproducibility to a different operator and a comparable apparatus in a different laboratory, with the original stating that only one in 20 results may exceed the limit. The original notes that these data come from tests in 1986, 1988 and others and do not fully meet the statistical requirements for determining precision. No suitable sample was available, so no bias test was performed; this boundary is not concealed and the table is not treated as an acceptance criterion for all heavy oils. | Liquid distilled / % | Repeatability / °C | Reproducibility / °C | | --- | --- | --- | | 10 | 6.1 | 16.9 | | 20 | 4.5 | 12.8 | | 30 | 6.1 | 13.5 | | 40 | 4.9 | 11.2 | | 50 | 5.7 | 14.2 | | 60 | 4.1 | 8.4 | | 70 | 4.8 | 11.4 | | 80 | 4.9 | 5.1 | | 90 | 4.4 | 4.4 |

12. Temperature response and temperature calibration: Original PDF pages 17-19, Annexes A and B. Annex A checks the cooling response in a water bath at 80 °C ± 5 °C, with the sensor heated to 70 °C and then transferred to a paper box of about 30 cm under specified conditions; if the interval for the drop from 30 °C to 5 °C above the equilibrium temperature exceeds 60 s, the sensor is not used. The result serves only for response qualification; the annex gives no precision or bias. A3.4 of the original heats to 70 °C and then removes the sensor, yet states that the cooling time is recorded from 30 °C; whether the transition is a problem in the original wording remains [to be verified], and it is not changed to 70 °C here. Annex B distinguishes the melting-point method from the routine boiling-point method; below is the study record of the original reference temperatures, not a statement of product purity, certificate or supply. The boiling-point method requires the parent substance to be at least 99.9% pure, and the calibration temperature is recorded to 0.2 °C. The metal bath must be held at least 10 °C above the melting point for at least 5 min before the cooling plateau is observed, and the plateau must last more than 1 min; Figures B1/B2 are not reconstructed here as manufacturing drawings, and calibration equipment, traceability and safety are verified separately. | Original calibration category | Substance / composition | Temperature / °C | | --- | --- | --- | | Melting point | Tin:lead:cadmium alloy (50:32:18) | 145.0 | | Melting point | Tin | 231.9 | | Melting point | Lead | 327.4 | | Boiling point at atmospheric pressure | Water | 100.0 | | Boiling point at atmospheric pressure | n-Heptane | 98.5 | | Boiling point at atmospheric pressure | Tetralin | 207.2 | | Boiling point at atmospheric pressure | n-Tetradecane | 252.5 |

13. Pressure calibration, dehydration and static holdup: Original PDF pages 19-21 and 24-25, Annexes C, D and F. Annex C uses a reference McLeod gauge for a full-range comparison. The calibration system is evacuated to 0.01 kPa and stabilized for at least 2 min; if the rise in the second 2 min exceeds 10%, the system must be checked; comparison values are recorded at more than three pressure levels. The schematic of the McLeod gauge arrangement is not a drawing from which the device can be purchased or built. Annex D of the original specifies nitrogen at 8 cm³/s, a cold trap at −70 °C, and an additional 3% to 5% of distillate after the water stops; cooling below 175 °C and water/oil separation below −5 °C belong to different steps. Equation (D1): W = 100A/B, where A is the mass of water collected (g) and B is the mass of the test sample (g). This dehydration annex gives no precision or bias for water content. Annex F deals with residual deposits; the original states that the residue on the inner walls exceeds 0.5%. Toluene at 10% to 20% of the normal charge is distilled briefly for about 3 min to wash the apparatus; after removal of the solvent the material is weighed, its density measured and it is treated as a separate fraction. The annex gives no precision or bias, and ventilation, solvent and heating risks are controlled by the formal procedure.

14. Record checklist and unresolved items: Original PDF pages 13-15 and 17-25; source-image verification in this round. The report retains the sample name, apparatus, operator, date, sample mass and density at 15 °C or 20 °C (four significant figures), volume, total volume gain/loss (0.1%), fractions and residue, and cumulative mass/volume percentages. Time, vapour/still-liquid temperatures, pressure, AET, rate and observed and corrected values are also retained. The record templates of Tables 3 and 4 have not been reconstructed as controlled laboratory records. This card covers 14 study chapters and the body/annex leads of the 25 pages held, but it is not the full text of the standard or the closure of a technical review. Figures 1-7, B1/B2, C1 and E1/E2 are not fully digitized, the nomographs have no verified algorithm, and the cover and copyright end pages have not been added to this file. Still to be verified: the 750-12 500 source figures in Table 2, the relationship between the 6 mm and the 10 mm position in Figure 3, the B−273 temperature scale in E4, the 0.266 kPa equality boundary in E2/E3, the base of the logarithm and the readings of the estimation charts. The years of the referenced standards, the final sample/apparatus applicability, technical acceptance and the independent Hermes/Grok acceptance are each to be confirmed; no product relationship is stated. The transition in Annex A between 70 °C and timing from 30 °C also retains a doubt in the original.

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