Basic Knowledge of Storage and Transportation
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A beginner is sharing the basic knowledge they have; I hope those more experienced can offer their support. Chapter 1: Properties of Oil Products 1. What are the precautions for storing petroleum products? Answer: (1) Check the oil tank for leaks in a timely manner. (2) Prevent the oil from boiling over due to excessive temperature or from becoming emulsified, which could cause deterioration of the oil. (3) Prevent oil leakage, emission, and cross-contamination due to inadequate inspection. 2. What are the characteristics of petroleum products? Answer: Petroleum products are characterized by being flammable, explosive, prone to generating static electricity, and toxic and harmful to human health. 3. What are the two main elements that make up oil? Answer: Oil is primarily composed of two elements, carbon and hydrogen, which account for 96–99% of its total elemental composition; among these, carbon makes up 83–87%, while hydrogen accounts for 11–14%. 4. What are the main production characteristics of refineries? Answer: (1) Flammable ； (2) Explosive ； (3) High temperature ； (4) High pressure ； (5) Prone to corrosion ； (6) Prone to poisoning. 5. What is the impact of the flash point of petroleum products on their storage and transportation? Answer: The risk of fire involving a petroleum product can be determined by its flash point level. The flash point is the lowest temperature at which a fire hazard arises; the lower the flash point, the more flammable the fuel, and the greater the risk of fire. Therefore, the various fire safety measures for its transportation, storage, and use can be determined based on its flash point. Chapter 2: Safe Production 6. How to prevent oil tank roof collapse accidents? Answer: (1) Strengthen a sense of responsibility, conduct frequent measurements, inspections, communications, and checks on the oil reception situation ； (2) When the oil level in the tank approaches the safe level, it is necessary to strengthen on-site inspections and switch tanks in a timely manner ； (3) Keep track of changes in oil intake in a timely manner ； (4) Do not rely too much on the level gauge; when there are abnormalities in the liquid level, it is necessary to pay attention, and if needed, go up to the tank to check the level, in order to prevent the level gauge from getting stuck and failing, which could lead to overflow. 7. Why is it necessary to regularly measure the oil tank levels? Answer: (1) Regular measurements allow for timely detection of changes in the amount of oil inside the tank, thereby preventing accidents such as leaks, spills, and cross-contamination. (2) Determine the amount of oil in and out during tank movement to assess whether the flow is normal ； (3) Check whether there are any leaks in the oil tank heaters and coolers. 8. When using a side-depth dipstick to measure the clearance, how is the oil level determined? Answer: Until the difference between two consecutive measurements is no more than 2 mm. If the difference between the second measurement and the first measurement is greater than 1 mm, the first measurement value is used as the oil level ； If the difference between the second measurement and the first measurement is greater than 1 mm, the average of the two measurements is taken as the oil level. 9. Under what circumstances is it strictly prohibited to use an oil dipstick? Answer: The oil dipstick must be in good condition when in use; it must not be used under any of the following conditions: the dipstick surface is twisted, bent, or repaired with solder ； The scale markings on the ruler are blurred or the numbers have fallen off ； Wear at the tip of the caliper hammer ； The scale error of the ruler exceeds the allowable range ； (5) Calibration tables issued without verification by a metrology department. 10. What is the liquid level stabilization time before measuring a oil tank? Why? Answer: The stabilization time of the oil surface before measuring a tank should be no less than 30 minutes. This is because, first and foremost, it is a matter of safety – the static electricity generated inside the tank after the flow of oil stops needs to dissipate completely, and it takes about an hour to reach a safe level. The second issue is accurate measurement; during the process of loading and unloading oil into the tank, there is significant disturbance in the oil inside the tank, with vortices or ripples on the liquid surface, which can cause measurement errors. Therefore, it is specified that a stabilization time of at least 30 minutes is required. 11. What is an upper sample? Answer: A sample taken at a depth of one-sixth of the distance below the free surface of oil or liquid petroleum products. 12. What is a central sample? Answer: A sample taken at a depth of one half of the distance below the free surface of oil or liquid petroleum products. 13. What is a lower sample? Answer: A sample taken at a depth of five-sixths below the free surface of oil or liquid petroleum products. 14. What is a top sample? Answer: Sampling taken at a depth of 150 mm below the free surface of oil or liquid petroleum products. 15. What is a bottom sample? Answer: A sample taken from the bottom of the oil tank or from the lowest point in the pipeline, from the petroleum or liquid petroleum products there. 16. Under what circumstances is it prohibited to use a densitometer? Answer: The densitometer must not be used in any of the following situations: (1) The glass has cracks or scratches ； (2) The density meter scale strip is loose ； (3) Loosening of small ballast metal pellets. 17. What are the methods for determining when a safety valve starts to operate? Answer: (1) Fluctuations in the pressure gauge ； (2) There is a beeping sound at the safety valve ； (3) It feels warm to the touch ； (4) Frosting on the pipeline of the liquid-phase safety valve trip. 18. What is the function of a drain valve? Answer: The function of a steam trap is to automatically remove the steam condensate from steam heating equipment or steam pipes. 19. How to use oil tanks correctly? Answer: (1) First, it is necessary to establish and improve the technical documentation for oil tanks, such as drawings and manuals. (2) Safe storage and transportation operations: Oil tanks that have been newly built or repaired must undergo pressure testing, and inspections should be carried out when receiving oil. (3) Strengthen daily inspection and maintenance management. (4) Effective measures should be taken when storing and transferring oil to reduce various forms of evaporation losses of the oil. 20. Why are heavy oil tanks, steam pipelines, and hot oil pipelines insulated? Answer: Insulation is used to reduce heat loss from heavy oil tanks, steam pipelines, and hot oil pipelines. Insulation helps save thermal energy, reduce the heating area, and lower the capacity of heating equipment. 21. What measures should be taken during the storage and transportation of oils to maintain product quality? Answer: (1) Strive to reduce oil evaporation losses and prevent oil from oxidizing and deteriorating ； (2) Prevent oil from mixing with water and mechanical impurities ； (3) Prevent oil crossover and mixing ； (4) Maintaining product quality requires strict adherence to the established systems. 22. What tasks should be done on rainy days? What should be noted during operation? Answer: (1) Cover the oil measurement holes and light-transmitting holes of the storage tank to prevent rainwater from entering the tank ； (2) Check the drainage conditions of facilities such as tank areas, storage tanks, and pump rooms, and inspect whether there is any sinking of the buildings ； (3) Wear a raincoat when working outdoors; the use of umbrellas is strictly prohibited ； (4) When working outdoors in heavy wind and rain, take precautions to prevent insulation sheets and other materials from falling and causing injury ； (5) Work on the tank top is strictly prohibited during thunderstorms and windy or rainy conditions of level 6 or above ； (6) When work must be carried out on the tank in strong wind conditions, two people must work together and effective safety measures must be taken. 23. What tasks should be carried out in snowy weather? What should be noted during operation? Answer: (1) Cover the oil measurement ports and light-transmitting ports of the storage tank ； (2) Clean the snow accumulation on the tank area, work passages, and related equipment in a timely manner ； (3) When working outdoors in heavy snowstorms, be careful to avoid being injured by falling metal sheets and other objects ； (4) During rainy or snowy weather, measures should be taken to prevent slips and falls, thus avoiding injuries to people ； (5) When it is necessary to work on the tank during severe snowstorms, two people must work together and effective safety measures must be taken. 24. Why is it necessary to heat storage tanks? Answer: (1) When oil is heated, its viscosity decreases, hydraulic friction is reduced, and its fluidity increases, which facilitates oil transportation and aids in operations such as oil processing, transfer, loading, and transport ； (2) Heating can achieve demulsification, removal of water contained in the oil, and settlement of impurities, which facilitates processing in the facility, ensures product quality, and also improves measurement accuracy ； (3) Heating during oil blending facilitates heat-induced convection of light and heavy fractions, resulting in a more uniform blending of the oils and ensuring better quality of the blended oil ； (4) During tank cleaning, in order to eliminate the residual oil at the bottom of the tank that has lost its fluidity, steam is often used directly for local heating, thereby helping the oil to melt and gain fluidity, which facilitates cleaning the bottom of the tank. 25. What measures should be taken during the storage and transportation of oils to maintain product quality? Answer: (1) Strive to reduce oil evaporation losses and prevent oil from oxidizing and deteriorating ； (2) Prevent oil from mixing with water and mechanical impurities ； (3) Prevent oil crossover and mixing ； (4) Maintaining product quality requires strict adherence to the established systems. 26. Under what circumstances is it necessary to clean pipelines? Answer: (1) The pipeline needs to be inspected and repaired ； (2) The type of oil in the pipeline needs to be changed ； (3) When the last tank of the same oil type within the same processing system is used up; (4) For oils that need to be heated when the temperature is below 100°C, after sales cease for the second shift on that day. 27. What are the measures to reduce evaporation losses? Answer: Based on the process by which losses occur, measures can be taken from the following aspects to reduce evaporation losses of oil products: (1) Reduce temperature fluctuations inside the tank ； (2) Increase the pressure resistance of oil tanks ； (3) Eliminate the gas space on the oil surface to prevent or minimize the release of gas outside the tank ； (4) Collect exhaled oil vapors, etc. 28. How to prevent oil tank boiling? Answer: (1) Strictly control the storage temperature of oil products ； (2) High-temperature oils must not contain water; water should be removed from the tank regularly ； (3) Any leakage in the heater should be repaired promptly. 29. What are the anti-freezing measures for the oil unloading equipment? Answer: (1) In winter, when the pipeline is not in use, it must be purged with steam and isolated using blind flanges. (2) Dehydration should be enhanced in each oil storage tank. (3) Keep the medium in constant flow within the pipeline. (4) Maintain the flow temperature at each steam vent point. 30. How to deal with frozen condensation in valves? Answer: When thawing and dehydrating a switch, it is necessary to turn the switch off first. When using steam for heating, approach the area to be thawed slowly in order to preheat it; this prevents sudden thermal expansion due to drastic changes in local temperature, which could cause the pipes to break and lead to danger. 31. What are the measures to reduce oil product losses? Answer: (1) Minimize leaks as much as possible, properly maintain all equipment in the oil storage and transportation system to eliminate leaks, and enhance the sense of responsibility among operators in order to prevent oil leakage incidents from occurring in oil tanks and tank trucks ； (2) Eliminate accidental oil mixing ； (3) Reduce the evaporation loss of oil products. 32. Why can heating be used to accelerate the settling rate of water in oil products? Answer: The settling speed of water in oil is proportional to the density difference between water and oil, and inversely proportional to the viscosity of the oil. It is also related to the stability of the oil-water emulsion. To increase the settling speed of water, it is necessary to reduce the viscosity of the oil as much as possible, increase the density difference between oil and water, and decrease the stability of the emulsion. By using heating, these objectives can be achieved simultaneously; therefore, the heating sedimentation method can accelerate the sedimentation rate of water in oil, facilitating its dehydration. 33. How to deal with oil freezing in pipelines? Answer: 1) For pipelines without insulation that have frozen, they can be thawed by direct heating with steam. 2) If freezing occurs due to a non-functional heat tracing line, the issue must be resolved first so that the heat tracing line can be put to use. 3) If only a portion of an insulated pipeline has frozen, a steam line can be inserted into the insulation layer to thaw it. 4) In cases where a long section of an insulated pipeline is frozen, it should be treated in segments. 34. What are the causes of boiling in oil tanks? Answer: When the temperature of the water droplets suspended in the oil tank rises high enough, the water is heated and vaporized, forming bubbles. Since the volume of water increases rapidly to more than a thousand times its original volume when it vaporizes, these bubbles rise swiftly, causing intense mixing. The expansion in volume carries the oil out of the tank, resulting in bumping in the oil tank. 35. Briefly describe the sequence of operations and precautions for measuring oil tank levels. Answer: The sequence of operations is: first measure the length, then take the temperature or collect a sample. Precautions: Place the ruler under the reference pad, do so firmly and at an appropriate speed; read the values first as decimals and then as whole numbers, and make proper records. 36. What are the main aspects of inspections in the tank farm? Answer: (1) Is the production in the tank farm operating normally, and is the process flow correct? ； (2) Are there any signs of leakage or spills? (3) Are the fire-fighting equipment in good condition? ； (4) Oil level changes ； (5) Inspect the heating system in winter to ensure proper frost and condensation prevention ； (6) Are there any unsafe factors in the surroundings? 37. What conditions are related to the evaporation loss of oil products? How is the relationship? Answer: The evaporation loss of oil is related to the storage temperature and pressure of the oil, its density, the evaporation area, as well as the relative flow velocity between the oil surface and the vapor. The higher the temperature, the greater the evaporation loss; the lower the temperature, the smaller the evaporation loss ； Losses decrease as storage pressure increases, while they increase when pressure decreases ； The higher the density of a liquid, the less likely it is to evaporate; the lower the density, the more likely it is to evaporate ； The larger the evaporation area, the greater the evaporation; the smaller the area, the less the amount of evaporation ； The greater the relative wind speed over the oil surface, the greater the evaporation loss. 38. What are the dangers of leaks? Answer: Leaks pose ten major hazards: they poison the air ； Harmful to the human body ； Contaminating water sources ； Corrosion equipment ； Cause an explosion ； Caused the fire ； Destroy buildings ； Increase consumption ； Dangerous agriculture ； It affects the appearance of the factory. 39. What preparations should be made before switching tanks? Answer: Before switching tanks, it is necessary to conduct a thorough and careful inspection of the process, equipment, and accessories. For the raw material tank, drain water first to check the oil level. When using the lifting and lowering pipes, open the valve of the tank being switched to first, and then close the valve of the tank that is being replaced. 40. What factors determine the safe height of an oil tank? Answer: To determine the safe height of an oil tank, it is necessary to take into account the flash point of the oil stored in the tank, the tank’s capacity, the thickness of foam required for fire suppression, the location of the foam generators, as well as the minimum and maximum temperatures of the oil. 41. What are the main causes of errors in length measurement? Answer: The main reasons for errors in measurement are as follows: (1) Work attitude: A lack of emphasis on measurement tasks, carelessness, sloppiness, disregard for quality, and a tendency to settle for minimum effort, leading to frequent mistakes ； (2) In terms of technical proficiency: a lack of specialized training in measurement techniques, low technical skill, and poor understanding of basic principles and operational procedures result in operations and calculations that do not meet the required standards, leading to data errors. (3) Regarding the implementation of procedures and regulations: operations are not carried out in accordance with established procedures; people try to cut corners by estimating values and oil quantities, and there is no verification of measurements ； (4) Errors in calculation: reading errors, tabulation errors, lookup errors, calculation errors, errors in transcribing records, and deliberately choosing too few digits for the calculation results ； (5) In terms of measuring instruments: inappropriate selection of such instruments, insufficient precision, substandard quality; continued use of instruments that have become inaccurate or damaged over time; inadequate periodic calibration; and poor management of measuring instruments. 42. What measures are taken to prevent oil from mixing with water during storage and transportation? Answer: (1) Keep the oil storage containers clean: That is, the containers must be washed before filling with oil, and only after inspection to ensure they meet the quality requirements of the oil to be stored can it be poured in ； Containers must be used for specific oils only and should not be mixed with each other ； The inner wall of the container is coated with rust-proof materials, etc ； (2) The longer the oil is stored and transported, the more precipitation is formed due to oxidation, and the greater the impact on the quality of the oil. Therefore, oil tanks should be cleaned regularly; cleaned and dried tanks and containers must be free of moisture, impurities, oil residue, and fibers, and should not leave any stains when wiped with a clean cloth ； (3) When loading or unloading oil products, operations should be halted in case of rain, snow, wind, or sandstorms ； (4) Strengthen the storage of bottled oil products. Classification and stacking of oil products upon storage ； Left outdoors under a tarpaulin cover ； It should be placed at a 45-degree angle ； Install the rubber ring around the barrel opening and tighten the barrel lid ； Before pouring in the oil, clean the oil residues and dust from the mouth and surface of the tank ； Strictly control the ambient temperature of stored oil products, etc ； (5) Regularly test and analyze the inventory oil, and apply the first-in-first-out principle when distributing the oil. 43. How to prevent oil mixing during storage and transportation? Answer: To prevent oil mixing, oils should be classified and used separately according to their different properties; oils with distinct properties must not be mixed through the same pipelines. If mixing is necessary, the pipelines should be purged with air, and where possible, steam can be used for purging as well, followed by further treatment of the oil before it can be used. 44. What are the regulations and precautions for water separation operations in oil tanks? Answer: (1) Allow 2 hours of settling before receiving material and after feeding it, and 4 hours for heavy oils before draining water; it is not allowed to drain water while the material is being received or processed. (2) When cutting off water, control the opening degree of the valve to prevent oil from being carried in by swirls; if oil is detected in the water, stop cutting off the water immediately. (3) Someone must be on site to supervise the water cutting operation. (4) It is strictly prohibited to drain water from two (or more) oil tanks simultaneously. 45. Why can the water that accumulates in equipment during winter freeze and damage the equipment and pipelines? Answer: Since most materials exhibit the property of expanding when heated and contracting when cooled, water behaves in the same way at temperatures above 40°C. However, below 40°C, it shows the opposite behavior, namely expansion when heated and contraction when cooled. Therefore, water has its maximum density at 40°C. When water freezes, its volume increases by about one-tenth. Based on the elasticity of water, an increase in volume of one-tenth can exert a pressure of over 200 Mpa on the pipe walls or fittings, causing them to break. 46. Why is it necessary to dehydrate crude oil before sending it to the processing unit? Answer: Excessive water content in crude oil can lead to a high vapor phase line speed in the distillation tower, resulting in unstable operation; in severe cases, this can even cause tower flooding. It also increases the load on the heating furnaces and the overhead condensers, as well as the load on the heat exchangers. Furthermore, it raises fuel consumption and cooling water usage, thereby reducing the actual processing capacity of the facility. 47. What abnormalities may occur to the oil in the tank during the heating process? How should it be handled? Answer: (1) If the oil becomes emulsified, the inlet and outlet should be closed promptly. After carefully identifying the cause, appropriate action should be taken immediately. (2) If there is oil or fire at the outlet of the heat source, it may be due to a broken heating tube; heating should be stopped immediately, and heating can resume only after the issue has been resolved. (3) The temperature drops, but both the steam inlet and outlet are open; in this case, it should be considered a heating blockage, and the system must be cleared using purging or other methods before heating can resume. 48. Why is it necessary to limit the storage temperature of oils? Answer: During storage and transportation, oils often need to be heated. As the temperature of the oil rises, its flow properties improve, but the risk of fire also increases. For light oils, the flash point is low; once the heating temperature exceeds this flash point, they can easily catch fire and explode in the presence of an open flame. For heavy oil, although its flash point is high, its auto-ignition point is low; when heated above this auto-ignition point, it will catch fire in the presence of air. For aqueous oil products, in addition to the aforementioned hazards, boiling over can also occur; therefore, the storage temperature must be strictly controlled and should not exceed 90°C. 49. What are the methods for dealing with a ruptured oil tank roof? Answer: (1) Immediately open the inlet line of the same oil tank ； (2) Pour the oil from the tank at risk of overfilling into other tanks until it reaches a safe level ； (3) Organize manpower to handle the spilled oil. 50. What regulations must be followed for various oil tanks in the oil storage area? Answer: The “three-dehydration” requirement must be implemented. (1) Dehydrate before oil collection to prevent water remaining at the bottom of the tank from being emulsified due to stirring during oil collection, which could affect measurement accuracy. (2) After oil collection, sedimentation and dehydration are carried out; moisture often exits along with the oil at the outlet of the device. Once the tank is full, it needs to be left to stand for 1–4 hours to remove the moisture, thereby facilitating further processing steps. (3) Dehydrate before moving to ensure that any residual water in the tank is not carried into the subsequent processing stages, thereby maintaining the quality of the product upon delivery.
51. What is the significance of measuring the density of crude oil? Answer: (1) It can be used for measurement; the weight of oil can be determined from volume and density ； (2) It provides some guidance for controlling production ； (3) The value of density indicates the purity of crude oil ； (4) To a certain extent, it is possible to determine the composition and type of crude oil ； (5) It is possible to approximately assess the changes in the quality of the oil. 52. What are the causes of oil leakage accidents? How should it be prevented? Answer: During the storage and transportation of oil products, the reasons for oil leaks are roughly as follows: (1) Lack of responsibility among staff, failure to conduct inspections, or leaving post in violation of regulations ； (2) Failure to operate in accordance with the process specifications, resulting in overheating, pressure buildup, etc ； (3) Unclear instructions or inadequate communication ； (4) Leaks in valves, heating pipes, etc ； (5) Malfunction of measuring instruments ； (6) Poor quality of maintenance work ； (7) Lack of anti-freezing and insulation, resulting in the freezing and cracking of valves or oil pipes ； (8) The oil storage and transportation equipment is old and in poor condition. Safety measures to prevent oil leakage: (1) Provide operators with ideological and safety technical training ； (2) Strictly implement the post responsibility system, conduct tank measurements on time, and avoid any mistakes ； (3) Strictly follow the operating procedures; avoid overheating and overpressure ； (4) Conduct thorough routine inspections ； (5) In the event of leaks or defects, take immediate action to resolve them ； (6) Regularly check the equipment for leaks to ensure the quality of maintenance work ； (7) Strengthen the water cutting operation for storage tanks ； (8) The communication and handover with relevant personnel must be clear. 53. What are the factors that affect the \"minor breathing\" loss in oil tanks? Answer: (1) It is related to the magnitude of diurnal temperature variations. The greater the temperature difference between day and night, the greater the loss due to \"minor respiration\" ； (2) It is related to the solar radiation coefficient of the area where the oil tank is located. The higher the solar irradiance coefficient, the greater the loss due to ‘minor respiration’ ； (3) It is related to the size of the oil tank. The larger the storage tank, the greater its cross-sectional area and evaporation area, which in turn results in higher \"minor breathing\" losses ； (4) It is related to atmospheric pressure. The lower the atmospheric pressure, the greater the loss due to ‘small breaths’ ； (5) It is related to the degree of filling of the oil tank. When the oil tank is full, the volume of the gas space is small, so the “minor breathing” loss is minimal ； A larger space volume means greater losses as well ； (6) It is related to factors such as the properties of the oil, including boiling point, vapor pressure, component composition, and the level of oil management. 54. What are the factors that affect the \"large breathing\" loss in oil tanks? Answer: (1) It is related to the properties of the oil. Oil has a low density; the more light fractions it contains, the greater the losses ； The higher the vapor pressure, the lower the loss ； The lower the boiling point, the greater the loss ； (2) It is related to the oil intake and discharge speed. The faster the oil inlet and outlet speeds, the greater the losses ； (3) It is related to the pressure level inside the tank. The higher the pressure resistance of the oil tank, the lower the breathing loss ； (4) It is related to the number of times the oil tank is rotated. The more times the oil tank is used, the greater the \"large breathing\" loss ； (5) It is related to factors such as the geographical location of the oil tank, atmospheric temperature, wind direction, wind force, humidity, and the level of oil management. 55. Practical significance of density measurement: Answer: Density is one of the most important physical properties of petroleum and its products. It is related to the composition, so its composition can be roughly determined based on density. Density is related to other properties such as boiling range and viscosity, which yields certain constants related to the composition; for example, in crude oil classification, the value of the characteristic factor (K value) is used to determine whether the oil is paraffinic, intermediate, or naphthic ； The composition of structure families is calculated using density and other physical properties, thereby determining the type of carbon and the composition of cyclic compounds, etc. In the manufacturing process and production, volume measurement is generally used, while the actual product is measured by weight at the time of shipment and calibration; therefore, density values are essential data. Density is one of the key parameters for controlling petrochemical products; for example, it determines the purity of benzene-based products. The density of jet fuel is related to its range of flight. By measuring the density of oils or chemical raw materials of the same type, it is possible to determine differences in their composition and distillation ranges, thereby assessing their suitability for specific uses. 56. Precautions for using a petroleum densitometer: Answer: The densitometer is a fragile glass instrument, so it must be handled with care during use. It should be wiped with absorbent cotton or other soft materials. Apart from holding the upper part of the densitometer with your hands when inserting it or removing it (make sure to do this vertically), its lower part should be removed during cleaning to prevent it from breaking. Samples with large temperature differences or those taken from refrigerated containers should be left at the ambient testing temperature for a period of time to eliminate errors that could affect the results. For products with viscosity and that are solid at room temperature, in order to obtain accurate data, they are heated and melted in an electric furnace or oven and then poured into a measuring cylinder. The cylinder containing the oil sample is placed in a constant-temperature water bath, and measurements are taken once the temperature has reached equilibrium. The melted sample cannot be poured into a measuring cylinder and immediately measured at room temperature, as a large temperature difference will result in overly high values. 57. The significance of measuring residual carbon: Answer: Residual carbon is related to unstable hydrocarbon compounds, polycyclic aromatic hydrocarbons, and non-hydrocarbon compounds in oils; it is particularly closely associated with asphaltenes and resins in heavy oils. For lubricant fractions, the carbon residue value reflects the degree of refinement, and carbon residue is one of the important indicators in the production process; it is also one of the specification requirements for commercial lubricants. 58. What is the significance of measuring the viscosity of petroleum products for production and use? Answer: The viscosity of oils generally increases as their boiling range increases. However, fractions within the same boiling range have different viscosities due to their varying chemical compositions. Among the hydrocarbons in oils, alkanes have the lowest viscosity, while cyclic hydrocarbons with long side chains and those with multiple side chains have the highest viscosity. Therefore, the degree of refinement of the lubricating oil is determined during the production process by analyzing viscosity control. Generally, the viscosity of the unrefined fraction is greater than that of the fraction refined with sulfuric acid, and the viscosity of the fraction refined with sulfuric acid is greater than that of the fraction oil refined with a selective solvent. Viscosity is one of the important parameters of diesel; it determines the atomization and combustion of diesel in internal combustion engines. High viscosity results in poor atomization, inadequate mixing with air, and incomplete combustion. At the same time, diesel serves to lubricate the plunger pump; if its viscosity is too low, it will impair the lubrication of the oil pump and increase plunger wear. 59. The importance of determining the freezing point of petroleum products for production and use. Answer: For waxy oils, the freezing point can be used as an indicator to estimate the wax content. The higher the paraffin content in the oil, the easier it is to solidify. If 0.1% paraffin is added to the oil, the freezing point increases by about 9–13 °C; conversely, removing paraffin from the oil results in a significant decrease in the freezing point. The freezing point is used to indicate the grade of diesel; for example, the freezing point of No. 0 diesel should not be higher than 0°C, while that of No. -10 diesel should not be higher than -10°C. Furthermore, the freezing point is also related to the lowest temperature at which diesel can flow smoothly through the engine’s fuel system; solid paraffin particles that form at low temperatures can clog the fuel filter and stop the fuel supply. 60. What is the significance of determining the flash point of petroleum products for production and application? Answer: The flash point of a petroleum product allows one to determine the lightness or heaviness of its distillation composition. Generally, the higher the oil vapor pressure and the lighter the distillate composition, the lower its flash point. Conversely, the heavier the distillate composition, the higher its flash point. During the operation of atmospheric and vacuum distillation units, the flash point is controlled in order to adjust the operating conditions of the side streams and produce high-quality distillates. The flash point can be used to determine the fire hazard of oils. The flash point is the lowest temperature at which a fire hazard arises. The lower the flash point, the easier it is to burn, and the greater the fire hazard. Therefore, flammable liquids can also be classified according to their flash point. Liquids with a flash point below 45°C are called flammable substances, while those with a flash point above 45°C are called combustible substances. The various fire safety measures for its transportation, storage, and use can be determined based on its flash point. 61. What is the significance of determining the water content in petroleum products for production and application? Answer: The fuel tank provides the accurate data on the volume of fuel. By subtracting the moisture content after measuring, the actual amount of oil in the entire container can be determined. The moisture content in the oil product is measured, and based on this level of moisture, a dehumidification method is determined to prevent the following hazards: (1) When moisture in petroleum products evaporates, it absorbs heat, which reduces their calorific value. (2) Moisture in light oils can deteriorate the combustion process. It can also bring dissolved salts into the cylinder, resulting in carbon buildup and increased wear on the cylinder. (3) At low temperatures, the moisture in the fuel freezes, blocking the fuel lines and filters and hindering fuel supply to the engine’s fuel system. (4) When there is moisture in petroleum products, it accelerates the oxidation and gelation of the oils ； (5) The presence of water in the lubricating oil can cause corrosion of engine components; at high temperatures, it can destroy the oil film on the metal surface, leading to wear. 62. What are the disadvantages of thiols in petroleum products? Answer: Gasoline contains a high amount of thiol compounds, which not only produce an unpleasant odor but also reduce the stability of the fuel. Because thiol is an oxidation initiator that can cause unstable compounds in oils to oxidize and polymerize, forming gel-like substances. Thiols are also corrosive and can increase the corrosivity of elemental sulfur. Furthermore, thiol also affects the sensitivity of oils to additives such as antiknock agents and antioxidants. From an environmental perspective, the use of gasoline containing high levels of thiol compounds increases the levels of SO2 and SO3 in vehicle exhausts, thereby exacerbating air pollution. 63. What is the reaction mechanism for gasoline desulfurization? Answer: The reaction mechanism for gasoline desulfurization is an anion-radical mechanism, and its kinetic sequence is as follows: RSH + OH- → RS- + H2O; Catalyst + 1/2O2 → RS- + Catalyst + 1/2O2; 2 RS˙ + RS˙ → RSSR + O2-2 + H2O → 2OH- + 1/2O2. The thiols in the oil first come into contact with NaOH, resulting in the formation of sodium thiolate, which then dissociates into the thiol anion RS-. At the same time, molecular oxygen forms unstable active complexes with the catalyst. The active complex undergoes a single-electron transfer reaction with the thiol anion RS- to form the thiol radical RS-. The two thiol radicals quickly combine to form the stable disulfide RSSH. The chemical equation for gasoline desulfurization is: 2RSH + O2 → RSSR + H2O. 64. What are the catalysts, promoters, and carriers used in solid-bed gasoline desulfurization? Answer: The main catalyst is cobalt polyporphyrin or sulfonated cobalt porphyrin ； The catalyst is a NaOH solution ； The carrier is activated carbon or molecular sieve. 65. What is the effect of temperature on the solubility of cobalt phthalocyanine? Answer: Excessively high temperatures can destroy the stability of cobalt phthalocyanine in alkaline solutions, thereby reducing the efficiency of desulfurization. The experimental data are shown in the table. Melting temperature/°C: 20, 40, 60, 88; Thiol removal rate/%: 74, 74.5, 77, 66.5. What is the effect of NaOH concentration on the thiol removal rate of cobalt polyphthalocyanine? Answer: The experimental data are shown in the table below. As can be seen from the table data, an increase in NaOH concentration is beneficial for the desulfurization reaction; however, too high a concentration can cause salting out and thereby reduce the efficiency of the reaction. NaOH concentration/% 5 10 20 40 Thiol removal rate/% 75 83 75 67 67. What is the effect of the temperature used in the desulfurization of gasoline on the thiol removal rate? Answer: The effect of the gasoline desulfurization reaction temperature on the thiol removal rate is shown in the table below. As can be seen from the data in the table, a reaction temperature of 40 degrees Celsius is appropriate, as gasoline volatilization is also low at this temperature. Reaction temperature/°C: 20, 30, 40, 50, 60; Thiol removal rate/%: 83, 91.7, 93.7, 88, 74, 68. What is the impact of the air/oil ratio on gasoline desulfurization? Answer: Under certain operating conditions, the effect of the air/oil ratio on gasoline desulfurization is shown in the table. As can be seen from the data in the table. When the air/oil ratio is greater than 1:1, it has minimal impact on gasoline desulfurization. In production, a large amount of air not only causes gasoline to oxidize and change color but also increases the loss of light components through volatilization. The actual air/oil ratio for desulfurization of alcohols in the catalytic unit of the Shanghai Refinery is only 1:39. Wind/oil (ratio): 1:1, 1:10, 1:20, 1:30. Thiol removal rate/%: 86.8, 87.5, 86.6, 86.5. 69. What is a Doctor solution? Answer: Dissolve 25 g of lead acetate (containing three molecules of water of crystallization) in 200 ml of water. Filter this solution into a 100 ml aqueous solution containing 60 g of sodium hydroxide; the resulting solution is then referred to as the Dr. solution. 70. What is a doctoral thesis? Answer: When the thiol-containing oil is mixed with the Drabber solution and a certain amount of sulfur is added, after shaking for 15 seconds and allowing it to stand for 1 minute, if the interface appears brownish-yellow or brown, it indicates the presence of thiols in the oil; the Drabber test fails in this case, which is indicated by a “+” symbol ； Conversely, compliance is indicated with “—”. The reactions in the doctoral experiments are as follows: Pb(OH)2 + 2RSH → (RS)2Pb + 2H2O; Lead thiolate ((RS)2Pb) + S → RSSR + PbS ↓ Disulfide. 71. How should a fixed-bed reactor be prepared for the desulfurization of gasoline using thiolates? Answer: Place 4–8 kg of cobalt polyphthalocyanine in an enamel bucket, add a dilute alkaline solution with a concentration of 5% at a temperature of 50–60 degrees Celsius, and stir it with a rod to dissolve it. The amount of alkali solution should not be excessive; as long as it is sufficient to dissolve cobalt polyphthalocyanine, that is sufficient. Prepare 10 m3 of an alkaline solution with a concentration of 10%, pour the dissolved catalyst into it, start the alkaline pump to circulate the mixture, and stir thoroughly to ensure uniform distribution. It is then drawn into the reactor for circulation, allowing the catalyst to be immersed and adsorbed on the activated carbon. The soaking is complete when the alkaline solution turns yellow. Pump the alkaline solution from the reactor into another container. 72. How is the solid-bed desulfurization and alcohol removal reaction regenerated? Answer: First, pump out the oil and waste alkali solution separately, then use water to displace the oil from the reactor, and finally introduce steam into the tank. After maintenance, the fixed-bed reactor was re-soaked in the newly prepared catalyst alkaline solution. Once the soaking is complete, the reactor is regenerated. Based on the experience of the refinery at Shanghai High Chemicals Company, the lifetime data for the gasoline desulfurization catalyst, polyphthalocyanine cobalt, is 90,000 tons of gasoline per kg of catalyst. If the lifespan of cobalt phthalocyanine is exceeded, the solid-bed reactor needs to be regenerated. 73. What is the alkali-free liquid fixed-bed deodorization method? Answer: In the alkali-free fixed-bed deodorization method, the preparation of the catalyst is the same as that in the conventional Merox fixed-bed deodorization method; that is, it is prepared using activated carbon as a carrier through an impregnation process. During operation, 10–20 ug/g of activator is added to the gasoline, which serves as the material to be deodorized. The activator is miscible with oil; it acts as a base during the deodorization process and also prevents contamination of the catalyst bed, remaining ultimately in the deodorized oil. Throughout the deodorization process, no alkaline liquid phase appears, and no alkaline liquid is discharged. Therefore, the alkali-free deodorization process is a clean deodorization method that produces almost no pollutants. However, the cost of the activator it uses is high. 74. Why is the thiolic sulfur content in denatured gasoline below 10 ug/g, yet it fails the Drabek test? Answer: The Drab test is a qualitative method for detecting thiol compounds, and many **use this test to check for thiols in fuels. For example, gasoline grade 90 requires passing the Drabek test or having a thiol sulfur content (SRSH) of less than 10 ug/g. But these two indicators are not exactly the same. Sometimes, the SRSH level is below 10 ug/g, or even less than 4 ug/g, yet the Dr. test fails, which directly affects the export of No. 90 gasoline in our country and results in huge economic losses. According to the mechanism of thiol oxidation, the oxidation of thiols to disulfides involves two steps: RSH + OH- → RS- + H2O (1) (oil phase) (alkaline phase); 2RS- → RSSO2 (2). The presence of an alkali is essential during the deodorization process. Whether it is the Merox liquid/liquid method or the conventional fixed-bed deodorization method, it is necessary for the thiol to transfer from the oil phase to the alkaline phase, thereby forming a thiol anion, i.e., reaction (1), followed by an oxidation reaction (2). For lower thiols, due to their good solubility in alkalis, reactions (1) and (2) occur easily; therefore, these two deodorization processes are effective for deodorizing lower thiols. However, for higher thiols, due to their low solubility in alkalis, they do not easily transfer from the oil phase to the alkaline phase; as a result, these two deodorization processes are difficult to effectively remove higher thiols. Thiols with different structures exhibit varying sensitivities in the Dober test. Generally speaking, lower thiols are not very sensitive to the Drabek test, whereas higher thiols are more sensitive to it. When gasoline contains 1.5 ug/g of dodecanethiol, its Drabek test yields a positive result (unqualified). Regarding the distribution of thiolic sulfur in the deodorized gasoline, higher thiols are the main components of the trace thiols present in it. Therefore, at present, in some domestic refineries, when the thiolic sulfur content in the degassed gasoline is below 10 ug/g, the Drabek test fails. 75. What is the “minor breathing” loss of oil tanks? Answer: When a oil tank is stored stationary, the loss caused by the day-and-night variations in the temperature of the gas space inside the tank is known as the tank’s “minor breathing” loss. 76. What are the contents of the “five no-acceptances” in the post responsibility system? Answer: (1) If the equipment issue is unclear, do not connect ； (2) Do not accept tasks if the orders issued by the workshop have not been completed ； (3) Jobs will not be accepted if the work area is not clean ； (4) Records that are unclear, incomplete, or inaccurate will not be accepted ； (5) Production is abnormal; no connection will be established if accidents are not addressed. 77. What are the contents of the “ten handovers” during shift change? Answer: The ten deliveries refer to: delivering tasks, delivering instructions, delivering raw materials, delivering operational parameters, delivering quality standards, delivering equipment, delivering problems and experiences, delivering safety measures, delivering tools, and delivering hygiene requirements. 78. What tasks need to be carried out during shift handover? Answer: During shift handover, it is necessary to ensure “three ones,” “four arrivals,” and “five reports.” “\"Three ones\" means handing over important production areas one by one, transferring key production data item by item, and delivering major production tools one at a time. “The four ‘dos’ mean that one should see what needs to be seen, touch what needs to be touched, hear what needs to be heard, and smell what needs to be smelled. “The “five reports” refer to reporting the inspection location, the safety status, the production status, the existing problems, and the measures taken.
Thank you to the original poster for sharing! I really learned a lot of knowledge!
It’s very practical; it’s an excellent teaching material for providing on-the-job skills and safety training to new employees
The materials are excellent and are very helpful for employee training.
Not bad. Do you have any knowledge of warehousing as well? (Storage knowledge for spare parts)
Thank you so much for sharing such great content, but it seems the original poster was very busy when posting it, as there are many spelling mistakes! It affects the quality; could you pay attention to this next time? These are just my humble opinions; please forgive me!
Great stuff, adding it to my collection! Thank you to the original poster
;P I’m a beginner – these are really useful. Thank you so much, haha