SH/T 0250-1992 Determination of Thermal Stability of Special Fuel Oil

AI-translated method card — human verification pending. This is not an official translation of the standard. Unclear source values remain unverified; check the original standard and product certificate before use.

Card type: Test method

1. Method number / full name / English name / replacement relationship

• Standard number: SH/T 0250-92
• Chinese name: Determination of Thermal Stability of Special Fuel Oil
• English name: not provided in the available source
• Replacement relationship: replaces SY 2452—82
• First issued: 1977 year (see additional notes)
• Approval/implementation: approved by China Petrochemical Corporation 1992-05-20, implemented on 1992-05-20

2. Scope of application and non-applicability

• This standard specifies a method for determining the fouling characteristics of fuel oil in a heater.
• This standard applies to special fuel oil.
• Not applicable: not provided in the available source.

3. Method principle

The sample, in a specially made glass heater, circulates by thermosiphon action and contacts the surface of a steel sleeve equipped with an internal heater. The inner wall temperature of the steel sleeve is 177±2.2℃; after maintaining for 6h, the deposit and discoloration on its surface are observed to evaluate the thermal stability of the fuel oil.

4. Reagents and materials (purity / preparation)

• 3.2.1 Emery cloth: grit size 180.
• 3.2.2 Metallographic abrasive paper.
• 3.2.3 Straight-run gasoline.
• 3.2.4 Industrial benzene.
• Purity requirements: not provided in the available source.
• Preparation method: not provided in the available source.

5. Apparatus and equipment

• 3.1.1 Glass heater: dedicated for fuel oil thermal stability testing, made of heat-resistant glass, shape and dimensions see Figure 1.
• 3.1.2 Steel sleeve:
  • Material: plain carbon steel (A3).
  • Shape: a long sleeve with one end open and one end closed, with a small groove on the inner wall.
  • Dimensions: outer diameter 12mm; total length 102mm; the width and depth of the small groove should be suitable for inserting the two-hole ceramic tube for thermocouple wires; the small groove length is about 65mm.
  • When polished and processed properly, the outer diameter shall be no less than 11.94mm, and the wall thickness shall be no less than 1.02mm.
• 3.1.3 Electric heating core (i.e., the internal heater of the steel sleeve): length 60mm, diameter 9mm, a rod-shaped body wound from heating wire, required to heat the steel sleeve to 200℃.
• 3.1.4 Thermocouple: nickel-chromium/constantan. The thermocouple for the 1 tube needs to be inserted into a two-hole ceramic tube of specification 3.2mm×2.2mm×1mm, about 100mm long. The thermocouples for the 2 and 3 tubes only need to be fitted with ceramic rings.
• 3.1.5 Temperature indicating recorder: small electronic potentiometer (or 303 millivoltmeter).
• 3.1.6 Variable power supply: 0.5kV voltage regulator.
• 3.1.7 Miniature single-phase AC series motor: for grinding the steel sleeve; may be omitted if unavailable.
• 3.1.8 Dispersing piece: a strip of tinplate (or other thin metal sheet) of 6.4mm×152mm×0.5mm, then wound three turns around a rod of diameter 8mm, pulled apart to a pitch, forming a spiral dispersing piece with a total length of 130mm.
• 3.1.9 Insulation layer:
  • For 1 tube: asbestos powder pressed into two semicircular concave layers, thickness 20mm, length 114mm, inner diameter 25.4mm (see Figure 1).
  • For 2, 3 tubes: an appropriate amount of asbestos rope and glass cloth.
• Figure 1 annotations (source-text extraction has much noise, dimension values require confirmation against the source standard (source-text extraction)): 1- heating tube (1 tube); 2- cooling tube (2 tube); 3- riser tube (3 tube); 4- cooler; 5-3 tube thermocouple sleeve; 6- rubber stopper; 7- steel sleeve; 8-1 tube insulation layer.

6. Recommended operating conditions

• 1 point temperature: 177±2.2℃.
• 2 point temperature: 85±5℃.
• 3 point temperature: 100±5℃.
• Test duration: counted from the start of heating, 6h.
• Temperature recording frequency: record the temperature at three points every hour.
• Glass heater installation: fixed vertically, ensuring an elevation angle of 5 degrees (original text as such, requires confirmation against the source standard (source-text extraction)).
• Cooling: after the test, cut off the power, increase the air blow or remove the insulation layer, and cool for about 10min.

7. Sampling and sample preparation

• 4.2 Sample preparation: the sample is required to be representative and free of water, with an amount of no less than 600ml.
• 5.2 Take about 300mL of a representative sample, heat to 60–71℃ (for oils with high freezing point, it may be appropriately increased), immediately slowly add it from the top opening of the 2 tube into the glass heater, controlling the oil amount appropriately (i.e., controlling the liquid level: after inserting the air cooler and the 3 tube thermocouple glass tube, the liquid level is exactly at the upper end of the 2–3 connecting tube). There must be no bubbles in the entire heater.

8. Analysis procedure

• 4 Preparation work
  • 4.1 Preparation of the steel sleeve
    • 4.1.1 For a properly processed steel sleeve, before each test, carefully grind it to a mirror-bright finish, first with emery cloth, then with metallographic abrasive paper.
    • 4.1.2 Wash the polished steel sleeve with straight-run gasoline (or benzene) and dry it.
    • 4.1.3 Insert the clean steel sleeve into the hole of a No. 5 rubber stopper (the hole diameter is a tight fit with the steel tube), adjust the end face of the stopper to be flush with the open end of the steel sleeve, and the closed end of the steel sleeve should be exposed outside by about 82mm.
    • 4.1.4 Place the two-hole ceramic tube containing the thermocouple wires tightly against the heating core along the length direction; after the thermocouple is placed in the steel sleeve, its junction position should be exactly at a distance of 38mm from the closed end (i.e., the 1 point temperature). Then insert the heating core together with the thermocouple ceramic tube into the steel sleeve, noting that the thermocouple ceramic tube is embedded in the groove on the inner wall of the steel sleeve, and the top end of the heating core touches the closed end of the steel sleeve.
    • 4.1.5 Firmly insert the polished and clean steel sleeve with the stopper into the heating tube 1, noting that the steel sleeve should be located on the centerline of the 1 tube, and the side with the groove on the inner wall should be on top.
  • 4.3 Fix the glass heater vertically on an iron stand, use an appropriate cork stopper to place the air cooler (cooling sleeve equipped with the corresponding cooling tube) into the center of the 2 tube, adjust and fix its bottom at 30mm above the upper part of the 2~1 connecting tube; additionally, place thermocouple wires along the outer wall of the cooler so that the junction is located at 25mm below the bottom of the cooler (i.e., the 2 point temperature), on the centerline of the 2 tube.
  • 4.4 Place the dispersing piece into the 3 tube until it reaches the bottom.
  • 4.5 Fit the 3 tube with an appropriate small rubber stopper, adjust and fix its thermocouple glass tube so that its bottom is at 140mm on the centerline of the 2~3 connecting tube (i.e., the 3 point temperature). When the glass tube is placed with the thermocouple, make the thermocouple junction closely contact the bottom wall of the glass sleeve. When the 3 tube is replaced with a mercury thermometer, the position of the mercury bulb should also be the same as the thermocouple junction position.
  • 4.6 Depending on the room temperature, the insulation layers of 2 and 3 may be appropriately fixed; if no insulation is needed and air cooling is required, first connect the compressed air line.
• 5 Test procedure
  • 5.1 Check whether all preparatory work is complete, whether the glass heater is vertical, ensuring an elevation angle of 5 degrees.
  • 5.2 Add sample (see Section 7).
  • 5.3 Immediately fix the semicircular concave insulation layer on the 1 tube.
  • 5.4 Turn on the power, adjust the voltage so that the temperature at the 1 point of the steel sleeve is 177±2.2℃, and record the test start time.
  • 5.5 Carefully observe the sample flow and the temperature changes at the three points 1, 2, 3, and check in detail whether the steel sleeve stopper leaks oil. If abnormal conditions are found, handle them promptly to avoid termination of the thermosiphon circulation due to a drop in liquid level caused by oil leakage, and to avoid interruption of the test due to blockage of small tubes caused by poor thermal stability that disrupts circulation.
  • 5.6 Record the temperature at three points every hour (temperature control range see Section 6).
  • 5.7 Counted from the start of heating, after 6h end the test, cut off the power, remove the electric heating core thermocouple, increase the air blow or remove the insulation layer, and cool for about 10min.
  • 5.8 Remove the air cooler and the 3 tube thermocouple tube (or mercury thermometer), rinse with gasoline and set aside. Then remove the entire glass heater and pour the sample out from the top opening of the 2 tube.
  • 5.9 Carefully take out the steel sleeve with the stopper (be careful not to touch the glass tube wall), clamp one end of the stopper with a clip, keep the steel sleeve in a horizontal position (note that the side with the groove on the inner wall is on top), and let the residual oil drip for 15min.
  • 5.10 Observe the appearance of the deposit on the steel sleeve and record it (i.e., the unwashed result). Then, with the closed end downward, immerse it into a beaker filled with 250mL benzene (or gasoline) up to the bottom of the stopper and shake gently to wash off the oil. Then immerse it into a second beaker filled with clean benzene (or gasoline) to the same depth for another rinse. After the benzene (or gasoline) evaporates, observe the appearance of the washed steel sleeve and record it (i.e., the washed but not wiped result). Finally, wipe a portion of the washed steel sleeve with a soft cloth (or fine filter paper) for further observation and record it (i.e., the washed and wiped result).

9. Qualitative and quantitative and calculation formula

• 6 Judgment of results
  • 6.1 Evaluate the appearance of the steel sleeve according to the table below, and judge the stability of the fuel oil; the result is expressed as stable, relatively stable, or unstable.

• 6.2 For the evaluation of the appearance of the steel sleeve (washed but not wiped), see Figure 2. Figure 2 annotations: 0— untested; 1— stable; 2— relatively stable; 3— unstable.
• Calculation formula: not provided in the available source.

10. Precision

• Not provided in the available source (only the repeatability judgment rule in the report of Section 7 is seen, see below).

11. Report

• 7 Report: take the two results of repeated determinations that are consistent as the judgment result. If not repeated, a third test should be conducted, and the two consistent results among them are taken as the judgment result.

12. Referenced documents

• Not provided in the available source (the main text does not list the normative references).

13. Source and verification

This page is an AI translation of the available Chinese method card. Human verification is pending. It is not an official translation of the standard. Check the source standard and product certificate before use.

14. Quick Answer Reference