Theoretical questions section of the national ethylene competition question bank

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I. Fill-in-the-blank questions 1. The final boiling point, also known as the dry point, refers to the highest distillation temperature (gas phase temperature) reached when all of the oil has vaporized. 2. The shape and position of the distillation curve are a reflection of its (chemical composition) in terms of physical properties. 3. The volume-averaged boiling point refers to the (average) temperature of the distillation temperature. 4. Viscosity is related to the velocity gradient and only becomes apparent when there is motion. 5. The viscosity of liquids (decreases) as temperature rises, while the viscosity of gases (increases) as temperature rises. 6. The characteristics of QC teams include obvious (autonomy) ； Widespread (mass-based) ； highly (**sexual) ； Rigorous (scientificity). 7. QC groups are classified into (field) type QC groups, (service) type QC groups, (problem-solving) type QC groups, and (management) type QC groups. 8. The ISO9000 family of standards includes (ISO9000), the fundamentals and terminology of quality management systems ； (ISO9001) Quality management system requirements ； (ISO9004) Guidelines for the effectiveness and efficiency of quality management systems ； The four standards are (ISO9011) Quality Management System Audit, Guidelines for Quality and Environmental Management Systems. 9. The weight per unit volume of a fluid is called the fluid’s (specific gravity) ； The mass per unit volume of a fluid is called the fluid’s (density). The ratio of the density of a fluid at 20°C to the density of pure water at 4°C is called (specific gravity). 10. 1 engineering atmosphere = (1) kilogram/cm2 = (0.0981) MPa. 11. The design pressure for high-pressure steam is (11.5) MPa, and the design temperature is (520) °C. 12. Before accelerating the turbine, it must be confirmed that the SS temperature is above (370)°C. 13. The critical pressure of ethylene is (5.11 MPa), and its critical temperature is (9.5°C). 14. The purpose of alkali washing in the alkali washing tower is (to remove acidic gases from the pyrolysis gas). 15. The compressor turbines in cracking plants can generally be classified by structure type into (back-pressure) type, (suction-condensing) type, and (fully condensed) type. 16. There are three basic ways of heat transfer, namely (conduction), (convection), and (radiation). 17. In a shell-and-tube heat exchanger, the flow of fluid through the tubes is referred to as flow through the tube side, while the flow of fluid through the gaps between the tubes is referred to as flow through the shell side. 18. The alkali scrubber tower is designed with a water washing section, whose purpose is to (capture the alkaline solution). 19. Proportional control refers to (the change in the regulator’s output being proportional to the deviation from the input change). 20. Absolute pressure = Gauge pressure + (Atmospheric pressure) ； Vacuum degree = (atmospheric pressure) - absolute pressure. 21. The utility station has four types of media: (air) lines, (nitrogen) lines, (water) lines, and (steam) lines. 22. The standard for successful nitrogen purging of the process system is N2 > (98%) and O2 < (0.2%). 23. The exhaust temperature of the condensing steam turbine shall not exceed (120)°C. 24. If the alkali concentration in the alkali washing tower is too high, (carbonate) crystals will form, and it generally should not exceed (15%)%. 25. Warming the pipes before starting the turbine is done to ensure that steam enters the turbine without any condensate, thereby preventing damage to the blades. 26. Warming up the turbine before startup is done to allow the machine to expand sufficiently before normal operation, thereby preventing vibrations caused by local deformation. 27. Specification for the filters used in the third-level filtration: (40–60) mesh filters for use from large oil drums to the oil storage tank ； From fuel tank to fuel filler: 80-mesh filter ； Fuel tank to equipment, using a (100-mesh) filter. 28. There are two ways media can leak through the seal ； First, there is leakage from the gasket itself; second, there is leakage from the compression surface. 29. The purpose of providing tear holes with a diameter of 8 millimeters in equipment such as Tanai liquid receiving trays and liquid seal tanks is to drain the residual liquid in the tanks through these tear holes during shutdown for maintenance. 30. Orifice plates and venturi flow meters can indicate the flow rate based on the pressure difference readings of the flow meter; these types of flow meters are collectively referred to as (differential pressure) flow meters. 31. A rotor flow meter measures the flow rate (amount) by utilizing a changing cross-sectional area; that is, the flow rate is determined based on the position of the rotor, and such flow meters are known as (cross-sectional) flow meters. 32. Write down the explosion limits of the following substances: Methane (5.0–15)% ； Ethylene (2.7-34%) ； Propylene (2.0-11.7)%. 33. The viscosity of liquids (decreases) as temperature rises, while the viscosity of gases (increases) as temperature rises. 34. The performance parameters of a centrifugal pump include (flow rate), (head), (rotation speed), (shaft power), and (efficiency). 35. The efficiency of a pump is the ratio of the pump’s (useful power) to its (shaft power). 36. To prevent foaming and structural issues caused by the condensation of pyrolysis gas in the alkali scrubber, the pyrolysis gas is heated by a heater to a temperature above its (dew point) temperature. 37. The standard for qualifying steam for pipe heating is that the steam temperature is more than 50°C above its saturation temperature. 38. The working principle of a refrigeration compressor is based on the (reverse Carnot cycle) principle, which includes four processes: compression, condensation, expansion, and evaporation. 39. For centrifugal compressors, at the same inlet pressure, the higher the density of the gas drawn in, the higher the output pressure. 40. In the alkali washing process for pyrolysis gas, if the alkali concentration is too high, the total salt content in the waste alkali solution after washing increases, which can lead to crystallization and blockage of the pipes. 41. Part of the H2S comes from the (raw materials), while the other part is generated when organic sulfur in the (raw materials) reacts with (hydrogen) and (water) at high temperatures. 42. There is a certain relationship between the alkali scrubber tower and the operating temperature; as the temperature of the scrubbing operation increases, the number of trays required decreases. 43. Increasing the alkali concentration (favors) the absorption of CO2, but it (reduces) the solubility of sodium carbonate, causing it to crystallize and precipitate easily. 44. The reason for the decrease in fuel tank level is (seal oil leakage). 45. The reason for the excessively high return oil temperature is (severe bearing heating). 46. The reasons for QW emulsification include an (excessively high) temperature of QW, the infiltration of (pyrolyzed light diesel) into the gasoline, which causes the (specific gravity) of the gasoline to approach that of QW, as well as an (excessively high) pH value of QW. 47. A decrease in the temperature at the bottom of the gasoline distillation column can reduce the flow rate and pressure of the recovered steam; some fractions (light fuel oils) will condense and mix into the heavy fuel oils. If the temperature at the column bottom is too low, condensation of steam can cause oil-water emulsification. 48. The lower the top temperature of the quench tower, the less (water vapor) and (gasoline) are introduced into GB-201. The average molecular weight of the pyrolysis gas (the lower it is), the work required by the pyrolysis gas compressor decreases, and its suction volume increases. 49. The general method for dealing with water hammer in steam pipelines is (opening the drain valve to release condensate), while the general method for dealing with water hammer in water pipelines is (opening the vent valve to release air). 50. Increasing the temperature at the bottom of the gasoline distillation column results in an increase in the viscosity of the quench oil at the bottom of the column, an elevation in the initial boiling point, and an increase in specific gravity. II. Multiple-choice questions: 1. In the PONA value of raw materials, O represents (B) A. Alkanes B. Olefins C. Cycloalkanes D. Aromatics 2. The main reason why CO causes poisoning is that CO (A) A. Has a binding capacity to hemoglobin 200-300 times greater than that of oxygen ； B. Lighter than air; C. It is a flammable gas ； D. Insoluble in water; 3. Among the following substances, those that are explosives are (B) A. Peroxides ； B. Trinitrotoluene ； C. Sodium nitrate ； D. Potassium chloride 4. The color of the paint applied to the outside of hydrogen cylinders is (A). A. Dark green B. Sky blue C. Gray D. Black 5. Among the following nitrogen-containing compounds, the one with the highest positive oxidation state of nitrogen is (C). A. NH3 B. (NH4)2SO4 C. HNO3 D. NO2 6. At a certain temperature, 100 grams of a potassium nitrate solution contains a grams of potassium nitrate; then the solubility of potassium nitrate at this temperature is (C) grams. A. a B. 100a/(100－a) C. a/(100＋a) D. a/(100－a) 7. Among the following substances, the one that is a homolog of CH2=CH—CH2—CH3 is (A), while the one that is an isomer of it is (B). A. CH2=CH—CH3 B. CH3—CH=CH—CH3 C. CH3－CH3 D. CH2=CH—CH=CH2 8. A compound in which the two single bonds in the carbonyl group are each connected to a hydrocarbon group is called (　C　). A. Alcohol B. Aldehyde C. The same D. Ester 9. When oil is heated above its flash point temperature, the lowest temperature at which the mixture of oil vapor and air comes into contact with a flame and results in continuous combustion is called (C). A. Flammability limit B. Lower explosion limit C. Ignition point D. Second flash point 10. Through (A), defects in the system can be identified, thereby further improving the compliance and effectiveness of the quality management system. A. Internal audit B. External audit C. Internal inspection 11. For orifice and venturi flow meters, the area of the throttling orifice (A); the pressure difference generated as the fluid flows through this orifice changes with the flow rate (A). A. Remains unchanged...changes B. Changes...changes C. Remains unchanged...remains unchanged D. Changes...remains unchanged 12. In rotor flow meters, the pressure difference generated as the fluid flows through the throttling orifice is kept constant (A), while the area of the throttling orifice changes with the flow rate (A). A Constant...Changing B Changing...Constant C Constant...Constant D Changing...Changing 13. Feedforward control is regulated according to (C). A The magnitude of the deviation from the given value; B The change in the measured value; C The magnitude of the perturbation. 14. What is meant by “de-tuning” is (C). A Intermittent drainage from the drum B Continuous drainage from the drum C High-pressure BW supply valve 15. Water hardness indicates (C). A Acidity and alkalinity B Corrosivity C Scaling tendency 16. The design temperature of the pyrolyzer flue gas is determined by (C) in the flue gas. A Carbon dioxide content B Carbon monoxide content C Dew point D Air volume 17. When the feed rate to the cracking furnace or the ratio of dilution steam is greater than the design values, the residence time (B) ； When above the designed cracking pressure, residence time (B). A Reduce...reduce B Reduce...increase C Increase...increase D Increase...reduce 18. The correlation index BMCI, also known as the aromatic index. The higher its value, the greater the aromaticity (B). A weaker B stronger C has no relation to this index. 19. During the alkali washing process, when there is a certain amount of (B) in the alkaline solution, Na2CO3 and NaHCO3 will crystallize out. A NaOH B Na2CO3 C NaHCO3 20. At normal temperature and pressure, the temperature will decrease after throttling in (C). A H2 B He C N2 D Ne 21. Under standard conditions, the volume occupied by 1 mole of any gas is (B) liters. A 2.24 B 22.4 C 224 D 2240 22. In industry, the amount of water contained in gases is generally expressed using (D). A percentage B density C molar ratio D dew point 23. Before starting the turbine compressor using an electronic speed controller, the regulator on the standby system should be set to (B) state. A Manual B Automatic 24. The minimum flow bypass design of centrifugal compressors is intended to prevent the compressor from (B) under low-load operation. A Overtemperature B Surging C Overpressure 25. The purpose of rotating the turbine compressor immediately after it is shut down is (A). A. Prevent the rotor from bending or deforming. B. Accelerate the cooling of the machine. C. Inspect the compressor. 26. A control valve that is controlled by the output signal of one regulator to operate two control valves simultaneously is called a (C). A. Cascade control B. Proportional control C. Zoned control 27. The purpose of heating the pyrolysis gas before alkaline washing is (B). A Increase the reaction temperature. B Prevent the pyrolysis gas temperature from dropping below its dew point and causing condensation. C Remove butter. 28. The function of the alkali scrubber tower in the pyrolysis gas compression system is (B). A. Adjusting pH; B. Removing acidic gases; C. Removing butter. 29. The basic principle of compression steam refrigeration is to utilize the properties of the working medium, by applying pressure to its vapor, to transfer heat from a colder substance (A) to a hotter one (A). A Absorbs heat... releases heat.. B Releases heat... absorbs heat.. 30. The critical pressure of ethylene is (A) MPa, and the critical temperature is ( ) °C. A 5.1...9.5 B 6.0...10.0 C 4.5...8.5 D 5.1...9.1 31. When the signal pressure from the regulator or valve positioner increases, the pneumatic diaphragm control valve actuator that moves its push rod downward is called an (A) actuator. An actuator in which the push rod moves upward when the signal pressure from a regulator or valve positioner increases is called (A) actuator. A Forward action...reaction B Reaction...forward action C Forward action...forward action D Reaction...reaction 32. The effective power of the pump is 80 KW, while the shaft power, as measured experimentally, is 100 KW. Therefore, the efficiency of the pump is (C) %. A 0.80 B 1.25 C 80 D 180 33. By changing the speed of a centrifugal pump, when the speed increases, the flow rate Q (A), and the head H (A). A Increase...increase B Increase...decrease C Decrease...decrease D Decrease...increase 34. The purpose of closing the pump outlet valve before starting a centrifugal pump is (A). A Reduce starting power B Increase the pressure at the pump outlet C Prevent sudden changes in system pressure D Prevent the suction line from emptying suddenly. 35. Increasing the stroke of a reciprocating pump will result in an increase in its discharge flow rate (A), while decreasing the number of reciprocations will result in a decrease in the flow rate (A). When starting the screw pump, (A) closes the outlet valve; (A) uses the outlet valve to regulate the flow rate. A Cannot... cannot B Cannot.. can C Can... can D Can.. cannot 36. A high temperature alarm signal will be issued when the compressor bearing temperature exceeds (C) °C. A 100 B 90 C 80 D 120 37. The type of GB-201 lubricating oil pump is (B). A Screw type B Centrifugal type C Reciprocating type 38. When a liquid flows steadily in a pipeline, if the diameter of the pipe is reduced by half, its flow velocity increases by (B) times. A 2 B 4 C 8 D 1/2 39. The head of a centrifugal pump is related to the lift height (B); the lift height refers to the vertical distance over which the pump transports liquid from a lower level to a higher one. When the pump is operating normally, its lift height is constant and equal to the (B) head. A: The same... equal to; B: Different... less than; C: Different... greater than 40. The pump casing of a centrifugal pump, also known as the pump body, serves to collect the liquid thrown out by the impeller, and to convert part of this liquid (B) into (B). A Static pressure energy...kinetic energy B Kinetic energy...static pressure energy 41. The compression process of pyrolysis gas is basically a (B) process, during which the gas pressure increases while the temperature also (B). A Isothermal...increase B Adiabatic...increase C Adiabatic...decrease 42. If the inlet gas pressure of a centrifugal compressor is the same, then (A). A inhaling gases with high density can result in a higher final pressure. B Inhaling gases with a low density can result in a higher final pressure. The density of the inhaled gas is independent of the final pressure. D Inhaling gases with a high density can result in a lower final pressure. 43. The reason why the suction pressure at one section of the ethylene or propylene refrigeration system is designed for positive-pressure operation is (B). A. Prevent surging B. Prevent air from leaking in C. Increase outlet pressure. 44. The balance disk of a centrifugal compressor is located at (B). A: Compressor inlet side; B: Compressor outlet side. 45. The higher the speed of a centrifugal compressor, the greater the anti-surge flow rate. A large B small 46. The purpose of closing the pump outlet valve before starting the centrifugal pump is (A). A Reduce starting power B Increase pump outlet pressure C Prevent sudden changes in system pressure D Prevent the suction line from collapsing suddenly. 47. When a compressor experiences surge, the pipelines connected to it experience pulsations with a (B) frequency and (B) amplitude. A High...Low B Low...High C Low...Low D High...High 48. When a compressor experiences surge, the frequency and amplitude of the vibrations are related to the amount of gas stored. The larger the reserve, the greater the frequency (A) and amplitude (A). A The lower... the greater B The greater... the lower C The lower... the lower D The greater... the greater 49. When a compressor experiences surge, the amplitude of the vibrations is reduced due to the check valve installed in the outlet pipeline, but the pulsation frequency increases as a result (B). A Decrease B Increase C Remain unchanged 50. The compression process of pyrolysis gas essentially belongs to (B) process, with the gas pressure rising while the temperature also (B). A Isothermal…increase B Adiabatic…increase C Adiabatic…decrease 51. The purpose of heating before alkaline washing of pyrolysis gas is (B). A Increase the reaction temperature. B Prevent the pyrolysis gas temperature from dropping below its dew point and causing condensation. C Remove butter. 52. The function of the alkali scrubber tower in the pyrolysis gas compression system is (B). A. Adjust pH B. Remove acidic gases C. Remove butter. 53. The function of the bypass line (hot line) for the five-stage discharge water cooler in the GB-201N system is (A). A. Increase the temperature of the gas from the \"five returns and four exits\" process. B. Use a bypass line when the heat exchanger is clogged. C. Use a bypass line when the load increases. 54. When a centrifugal compressor experiences surging, the larger the volume of the pipeline equipment, the greater the amplitude of the vibrations, and the smaller the frequency. A Large...Small B Large...Large C Small...Small D Small...Large 55. The discharge temperature of a centrifugal compressor generally should not exceed (B)°C; otherwise, it will damage the (B) of the compressor. A 100...dynamic balance B 120...static balance C 120..static balance D 100...static balance 56. The higher the speed of a centrifugal compressor, the (greater) the anti-surge flow rate. A large, B small. 57. The critical speed of a centrifugal compressor (B). A: All have it; B: Not necessarily; C: None have it. 58. During the process of removing acidic gases using alkali washing, (C) can be removed. A Inorganic sulfur B Organic sulfur C Inorganic sulfur and some organic sulfur 59. Increasing the inlet temperature of carbon dioxide hydrogenation can (A C). A Increase the catalyst’s activity B Decrease the catalyst’s activity C Decrease the catalyst’s selectivity D Increase the catalyst’s selectivity 60. The adsorption capacity of molecular sieves increases as (B). A Higher temperature results in a higher adsorption capacity. B Higher temperature results in a lower adsorption capacity. 61. Molecular sieves should be dehydrated at (C) and regenerated at (C). A Low temperature, low pressure… High temperature, high pressure B High temperature, low pressure… Low temperature, high pressure C Low temperature, high pressure… High temperature, low pressure C High temperature, high pressure… Low temperature, low pressure 62. In a demethanization tower, under certain temperature and pressure conditions, the ethylene content in the overhead gas increases as the molecular ratio of H2 to CH4 increases (B). A Decrease B Increase C Unchanged D Irrelevant 63. (A) refers to the process in which, after H2 and CH4 are separated at the top of the demethanization tower from the pyrolysis gas, H2 and CH4 proceed to a cryogenic tank where further separation is carried out to obtain over (A)% H2. A Post-cooling...80 B Post-cooling...95 C Pre-cooling...80 D Pre-cooling...95 64. In the pyrolysis gas separation process, the option with the lowest separation temperature, the highest cooling energy consumption, and the greatest loss of ethylene is (B). A Ethylene distillation column B Demethanization column C Deethanization column D Refrigerator 65. The greater the relative volatility of a binary mixture, the more tower plates are required (B). The more A, the less B. 66. As the operating pressure increases, the concentration of the heavier components in the gas phase (B) increases, while the concentration of the lighter components in the gas phase (A) decreases. A increases B decreases. 67. The throttling expansion of methane in a refrigerator is (B); the greater the pressure drop, the more (B) the temperature after throttling. A Isobaric expansion: High B Isobaric expansion: Low C Adiabatic expansion: High D Adiabatic expansion: Low 68. The required propylene content in the propylene product is not less than (C) A 99.0 B 99.9 C 99.6 D 99.4 69. During the heating up of the cracking furnace, (B) is removed at low temperatures and constant pressure, while (B) is removed at high temperatures and constant pressure. A Crystal water, Free water B Free water, Crystal water C Saturated water, Crystal water D Surface water, Free water 70. Which of the following methods is not a common method for storing ethylene? (D) A Storage in underground salt caverns B Storage at atmospheric pressure C Storage at low temperatures D Storage at room temperature 71. There are mainly three types of compression processes: isothermal compression, adiabatic compression, and polytropic compression. In practical applications, the compression of cracking gas generally involves (B). A Isothermal compression B Polytropic compression C Adiabatic compression 72. Which of the following is not a way in which static electricity can be generated? (B) A Induction B Leakage C Friction D Adhesion E Polarization 73. Among ethane, propane, and butane as raw materials, (B) results in the lowest yield of ethylene. A Butane B Propane C Ethane 74. For a compressor, when the gas temperature at the inlet is (A), and the molecular weight and pressure are (A), if the outlet pressure does not decrease accordingly, the operating point will move closer to the surge threshold line. A Rising Falling B Rising Rising C Falling Rising D Falling Falling 75. For carbon dioxide hydrogenation catalysts, the order of selectivity is (C) A Co＞Ni＞Pd B Ni＞Pd＞Co C Pd＞Co＞Ni D Pd＞Ni＞Co 76. For Pb-based catalysts, the correct order of adsorption capacity for different hydrocarbons is (D). A Alkynes > Monoenes > Dienes > Alkanes B Monoenes > Alkynes > Dienes > Alkanes C Monoenes > Dienes > Alkynes > Alkanes B Alkynes > Dienes > Monoenes > Alkanes 77. Catalysts used in methanation reactions generally employ catalysts with (A) as the active center. A Ni B Pb C Co D Ag 78. After the pipeline construction is completed, when using a gas purging method for the system, the flow velocity of the purging gas should be no less than (D) M/S. A 5 B 10 C 15 D 20 79. The maximum height to which a catalyst can fall should generally not exceed (C) mm. A 60 B 100 C 600 D 1000 80. The residence time as used in industry is (B) A integral residence time B apparent residence time C apparent residence time D true residence time 81. Among the following raw materials, (A) has the highest standard cross-temperature. A Ethane B Naphtha C Light diesel D Hydrogenation tail oil 82. Which of the following statements is incorrect? (B) Increasing the temperature and reducing the residence time facilitate the production of more ethylene from n-alkanes ； Increasing the temperature and reducing the residence time are beneficial for the formation of low-molecular-weight branched alkenes from isoparaffins ； Increasing the temperature and reducing the residence time will decrease the yield of monoolefins other than propylene ； Increasing the temperature and reducing the residence time will decrease the yield of pyrolysis gasoline ； 83. At higher pyrolysis depths, which of the following indicators is not suitable for measuring the pyrolysis depth? (C) A. Methane yield B. Ratio of methane yield to propylene yield C. Yield of C3 and lighter components D. Ratio of methane yield to propane yield 84. Among the following furnace tube materials, which one has the highest temperature resistance? (C) A HK-40 B HP-40 C 28Cr48Ni D Cr25-Ni35; niobium or tungsten is added to the furnace tubes. 85. Among the following methods, (A) is not one of the methods used for producing ethylene through cracking. A. Catalytic cracking method B. Regenerative furnace method C. Superheated steam method D. Plasma method 86. The quenching temperature of the pyrolysis gas is mainly determined by (D). A Water-to-oil ratio B Furnace outlet temperature C Bubble point temperature of the pyrolysis feedstock D Hydrogen content in the feedstock. 87. TLX generally does not adopt the (C) form. A Shell-and-tube type B Tubing type C Tube-in-box type D Shell-and-tube column type. 88. To ensure the proper operation of the quench oil system, the viscosity of the quench oil should be kept below (C) m2/s at 50°C: A 5 B 10 C 5×10-4 D 10×10-4. 89. To improve the thermal efficiency of the cracking furnace, (A) is the incorrect approach. A Increase the opening degree of the air valve in the pyrolysis furnace burner. B Operate by reducing the flue gas temperature to a level close to the dew point temperature. C Design the convection section appropriately. D Use refractory materials with good insulating properties. 90. The factors that affect pyrolysis include the conditions under which pyrolysis takes place, the type of pyrolysis furnace, the structure of the furnace, and the properties of the raw materials. Among them, (D) plays the most important role. A. Conditions for cracking B. Type of cracking furnace C. Structure of the cracking furnace D. Properties of the raw material 91. Among the following hydrocarbons, the correct order of the characteristic factor K values is (C). A Butane > Cyclopentane > Pentane > Toluene B Toluene > Cyclopentane > Pentane > Butane C Butane > Pentane > Cyclopentane > Toluene D Toluene > Pentane > Cyclopentane > Butane 92. Which of the following statements regarding the hydrogen content in the feedstock is incorrect? (D) A The yield of ethylene in the pyrolysis gas decreases as the hydrogen content in the pyrolysis feedstock decreases. At the same hydrogen content, the characteristic factor K of the pyrolysis feed increases as the average boiling point of the feed rises. The gas generation rate of C pyrolysis gas increases with the increase in hydrogen content in the feedstock. The yield of C5+ liquid products in the D pyrolysis gas decreases as the hydrogen content in the pyrolysis feedstock decreases. 93. For quench waste heat boilers, (D) has no effect on suppressing secondary reactions and coking. A High mass flow rate of pyrolysis gas B Short residence time C Low pressure drop D Lower drum pressure 94. Which of the following substances can cause permanent poisoning of the carbon dioxide hydrogenation catalyst? (C) A H2S B CO C AS D H2O 95. For the same outlet pressure, compared to five-stage compression with four-stage compression, (D) A the process is simpler and requires less investment; B the compression ratio is higher; C the temperature of the pyrolysis gas at the outlet is higher; D the power consumption is lower. 96. When the sulfur content in the pyrolysis feedstock is (A), using alkali washing is the most economical method. A ≤0.1% (pure) B 0.1%≤0.5% (pure) C >0.5% (pure) D ≤1% (pure) 97. Among the following methods, (A) is not suitable as a method for treating waste alkaline solutions. A. Hydrochloric acid neutralization method B. Sulfuric acid neutralization method C. CO2 neutralization method D. Air oxidation method 98. At a pressure of 3.7 MPa, the starting temperatures for the formation of hydrates of the following hydrocarbons, listed from highest to lowest, are correct as follows: (B) A. CH4 > CO2 > C2H4 > C2H6 B. C2H6 > C2H4 > CO2 > CH4 C. CO2 > C2H6 > C2H4 > CH4 D. CO2 > CH4 > C2H4 > C2H6 99. The substance that cannot be used for thawing is (D): A. Ammonia B. Methanol C. Ethanol D. Ethanolamine 100. Among the following gases, which one has the highest water content? (A) A. Pyrolysis gas with a dew point of -55°C B. Pyrolysis gas with a dew point of -60°C C. Air with a dew point of -55°C D. Air with a dew point of -60°C 101. An excessive residual adsorption amount after desiccant regeneration may be due to (A). A. The temperature distribution in the bed is uneven during regeneration. B. The regeneration temperature is high. C. The dew point of the regeneration gas is low. D. The heating rate during regeneration is slow. 102. In the pre-deethanization hydrogenation process, the light fractions from the top of the deethanizer are sent to (C). A. The demethanizer. B. The depropanizer. C. The acetylene hydrogenation reactor. D. The pyrolysis gas dryer. 103. In the pre-depropanization separation process, the feed to the deethanizer mainly consists of (B). A. Hydrogen, methane, C2, and C3 fractions. B. C2 and C3 fractions. C. Fractions above C2, with light components such as hydrogen and methane removed. D. C4 and higher fractionals. 104. When the acetylene concentration in the reactor feed is above (B), full-fraction hydrogenation is advisable. A 1% B 1.5% C 0.5% D 0.9% 105. The correct order of the adsorption rate of hydrocarbons by a catalyst is (C) A Alkynes > Alkenes > Dienes > Saturated alkanes B Alkynes > Dienes > Saturated alkanes > Alkenes C Alkynes > Dienes > Alkenes > Saturated alkanes D Dienes > Alkynes > Alkenes > Saturated alkanes 106. Regarding catalytic selective hydrogenation, which of the following statements is incorrect? (B) A Increasing the temperature enhances the catalyst’s activity but reduces its selectivity. B Carbon monoxide can improve both the selectivity and activity of the catalyst. C An excessively high space velocity significantly reduces the surface activity of the catalyst. D Increasing the reaction pressure facilitates the reaction process, thereby increasing the conversion rate. 107. On palladium catalysts, the correct order of the strength of adsorption of various compounds is (B) A Sulfides > Butadiene > Acetylene > Propyne B Sulfides > Carbon monoxide > Ethylene > Carbon dioxide C Sulfides > Ethylene > Carbon monoxide > Carbon dioxide D Carbon monoxide > Sulfides > Acetylene > Ethylene 108. If the temperature in the acetylene hydrogenation reaction gets out of control and rises to 400°C, then (B) reaction will occur; if it remains uncontrolled and reaches 650°C, then (B) reaction will take place. A Non-contact exothermic decomposition B Decomposition with non-contact exothermic reaction C Polymerization with non-contact exothermic reaction D Hydrogenation and decomposition 109. Among the methods listed, (C) is not suitable for storing liquid ethylene. A: 2.0 Mpa, -30°C; B: 107 Kpa, -103°C; C: Storage in salt caves at normal temperature and pressure; D: 10 Mpa, 25°C. 110. When 100 kg of ethane (100% pure) is cracked, with a one-pass conversion rate of 60%, the yield of ethylene is 46.4 kg. After separation, all of the reacted ethane is returned to the cracking process. What is the total mass yield of ethylene? (B) A. 74.4% B. 77.3% C. 82.8% D. 49.5% 111. The alkali washing process cannot remove (D). A. COS B. CS2 C. RSH D. CO 112. In the same series of pipes, the larger pipe has a diameter of Φ89×4 mm, while the smaller pipe has a diameter of Φ57×3.5 mm. Given that the flow rate of water in the larger pipe is 0.9 m/s, what should be the flow rate of water in the smaller pipe? (A) A. 2.36 m/s B. 2.42 m/s C. 1.40 m/s D. 1.458 m/s 113. For centrifugal pumps, changing (C) will not increase the pump’s head. A Rated speed of the pump B Impeller diameter C Density of the fluid being transported D Changing the degree of blade curvature 114. When measuring temperatures at -160°C, which type of thermocouple should be used? (A) A Copper–Constantan B Nickel-chromium–Nickel-aluminum C Iron–Copper-nickel D Copper–Copper-nickel Which of the following methods is not suitable for treating sulfur-containing wastewater? (A) A Steam stripping method B Activated sludge method C Pure oxygen aeration method D Biofilm method 116. Which of the following methods is not suitable for treating waste alkali? (D) A. Acid addition neutralization method; B. Carbonate neutralization method; C. Catalytic oxidation method; D. Biofilm method. 117. The air environmental quality standards are divided into (A) grades. A three B four C five D six 118. Among the hydrocarbons listed below, which one has the widest explosion limit? (B) A Methane B Ethylene C Ethane D Ammonia 119. Which of the following statements is incorrect? (A) A The proportionality of a proportional controller is the same as its amplification factor. The larger the gain of the B proportional regulator, the smoother the transition process curve, but the greater the error margin. The smaller the gain of the C proportional regulator, the more oscillatory the transition process curve becomes. Divergent oscillations may occur when the proportional gain is too low. The output variation of the D-integral control action is proportional to the integral of the input error; in other words, the rate of change of the integral output is proportional to the input error. P=K1∫edt. 120. If the moisture content of air with a dew point of -55°C is 13PPM, then the moisture content of pyrolysis gas with the same dew point and a molecular weight of 22 is (B) A 16ppm B 17ppm C 18ppm D 20ppm. 121. Which of the following flow meters does not belong to the differential pressure type of flow meters? (C) A Jet flow meter B Venturi flow meter C Rotameter D Orifice flow meter. 122. With all other conditions remaining constant, reducing the reaction temperature will cause the reaction equilibrium to shift in the direction of (B). A Endothermic B Exothermic C Neither endothermic nor exothermic. 123. The factors that may lead to the formation of green oil during the hydrogenation of carbon dioxide and carbon three compounds are (D) A High catalyst selectivity B High catalyst activity C High hydrogen-to-acetylene ratio D Excessively high temperature. 124. The control method suitable for situations where the time constant of the process variable is small, the system load varies greatly, the pure lag value is large, and it is not permissible for the controlled parameter to deviate from the set value is (B) control. A Proportional control B Proportional-integral control C Proportional-integral-derivative control D Integral-derivative control 125. Currently, the primary method used for ethylene production is (D). A Catalytic cracking method B Superheated steam method C Heat storage furnace method D Tubular furnace cracking method 126. Which reaction does not occur during the cracking of aromatics? (D) A Chain reaction B Dehydrogenation reaction C Condensation reaction D Aromaticization reaction 127. Safety valves can be classified according to their working principle as (C) A Slightly open type, Moderately open type, Fully open type B Closed type, Semi-closed type, Open type C Spring-type, Weight-type, Lever-type, Guided-type 128. Among the following furnace types, (D) has the shortest residence time. A SRT-I B SRT-Ⅱ C SRT-Ⅲ D SRT-IV 129. The purpose of using a two-stage quenching boiler at the outlet of the pyrolysis furnace is (A B) A to reduce the residence time of the pyrolysis gases B to increase the selectivity of the pyrolysis reaction C to reduce equipment costs D to accommodate heavy-duty pyrolysis feedstocks 130. In the amine process for removing acidic gases, amine reacts with which of the following substances and cannot be regenerated thereafter? (C) A Butadiene B Inorganic sulfides C Carbonyl sulfide (COS) D H2S 131. The structural formula of glycerol is (D). 132. Among the following substances, the one that is a homolog of CH2=CH—CH2—CH3 is (A), while the one that is an isomer of it is (B). A. CH2=CH—CH3 B. CH3—CH=CH—CH3 C. CH3－CH3 D. CH2=CH—CH=CH2 133. The functional group (–COOH) present in the molecule of acetic acid is called (C). A. Hydroxyl group B. Carbonyl group C. Carboxyl group D. Methyl group 134. A compound in which the two single bonds of the carbonyl group are each connected to a hydrocarbon group is called (C). A. Alcohol B. Aldehyde C. The same D. Ester 135. Among the following substances, which one has the highest boiling point? (A) A. NH3 B. C3H6 C. C3H8 D. CH4 136. Comparison between the pre-deethanization process and the sequential separation process: (A, C) A. The C3 and C4 fractions do not enter the demethanization tower, allowing for more efficient use of cooling energy ； B is suitable for separating pyrolysis gases with various compositions. C If a pre-hydrogenation process is used simultaneously, it will simplify the process and reduce costs. D This also applies to pyrolysis gases with a high content of butadiene. 137. During the pyrolysis process, the selectivity for ethylene is generally expressed using (A). A Weight yield ratio of methane to ethylene B Weight yield ratio of methane to propylene C Weight yield ratio of ethylene to propylene D Weight yield ratio of methane to propane 138. The main factors that affect the selectivity of ethylene during the cracking process are (A C) A Average residence time B Operating pressure C Average hydrocarbon partial pressure D Dilution steam ratio 139. In ethylene production, the “three efficiencies” that are often emphasized in improving cracking furnaces do not include (B) A Aromatic yield B Conversion rate C Thermal efficiency D Cracking furnace utilization rate 140. Regarding the thermal efficiency of cracking furnaces, which of the following statements is incorrect? (C) A Excess oxygen content leads to a higher CO content in the flue gases, which may result in secondary combustion and reduced thermal efficiency ； To reduce the excess air volume, it is necessary to adjust the burner operation in order to keep the oxygen content in the flue gases at 2–3% ； C To improve the thermal efficiency of the pyrolysis furnace, it is necessary to keep the furnace operating under a high negative pressure as much as possible ； D To reduce the thermal efficiency of the pyrolysis furnace, heat loss from the furnace walls should be minimized as much as possible ； 141. If the inlet of the convection section of the cracking furnace appears blue and misty, while the bottom of the furnace is clear, the possible cause is (D). A. Uneven flame distribution B. Excessive air supply C. Positive pressure in the furnace D. Insufficient combustion air. 142. Among the methane separated by the cryogenic unit and demethanization system, the correct order of ethylene content is (B). A. High-pressure methane > Medium-pressure methane > Low-pressure methane B. Low-pressure methane > Medium-pressure methane > High-pressure methane C. Medium-pressure methane > High-pressure methane > Low-pressure methane D. Low-pressure methane > High-pressure methane > Medium-pressure methane. 143. In the catalyst regeneration process, the incorrect step is (B). A. Heating the methane B. Heating with steam at 150°C C. Maintaining a constant temperature with steam at 370°C D. Drying the methane at 200°C. 144. The temperature range for which nickel-chromium/nickel-aluminum thermocouples can be used is (C)°C. A. 0–500 B. –200–200 C. –200–1300 D. –100–500. 145. When the tower pressure decreases, the concentration of light components at the top of the tower (B). A. Increases B. Decreases C. Remains unchanged. 146. The explosive limit of ethylene in air is (D)% (by volume). A. 2.2–63 B. 3.1–63 C. 2.2–36 D. 2.7–36. 147. The quenching temperature of the cracking gas has no relation to (A) of the cracking gas. A. Yield B. Dew point C. Hydrogen content D. Volume average boiling point. 148. The critical properties of ethylene are (A). A. Critical temperature: 9.5°C, critical pressure: 5.1 Mpa. B has a critical temperature of 19.7°C and a critical pressure of 53.1 Mpa. C: Critical temperature is 36.5°C, and critical pressure is 6.2 Mpa. 149. Rank the following hydrocarbons in order of their ease of cracking. The correct answer is (D): A. Isoparaffins > Naphthenes > Hexacyclic hydrocarbons > Pentacyclic hydrocarbons; B. Naphthenes > Isoparaffins > Pentacyclic hydrocarbons > Hexacyclic hydrocarbons; C. Naphthenes > Hexacyclic hydrocarbons > Pentacyclic hydrocarbons > Isoparaffins; D. Naphthenes > Isoparaffins > Hexacyclic hydrocarbons > Pentacyclic hydrocarbons. 150. For a depropanization tower, the key component is (B). A Propylene and propane B Propane and butadiene C Propylene and butadiene D Propyne and propane III. True or False Questions 51. Before starting a centrifugal pump, the pump outlet valve should be closed to reduce the starting power and prevent overload; the pump outlet valve is then opened after it starts running. (√) 52. If a filter has a filtration rating of 10 microns, it means that the filter is capable of removing solid particles with a diameter greater than 10 microns. (√) 53. The function of the lubricating oil system pressure reservoir is to ensure a reliable switching between the main oil pump and the auxiliary oil pump, thereby preventing interlock actions caused by low pressure during the switching process. (√) 54. The minimum flow bypass in centrifugal compressors serves to prevent the compressor from overheating during operation at low loads. (X) 55. For centrifugal compressors, at a constant outlet pressure, the lower the inlet pressure, the lower the power consumption. (X) 56. The purpose of using lubricating oil is to reduce friction and wear in bearings, thereby improving efficiency and extending their service life. (√) 57. When the temperature of a gas is higher than its critical temperature, compressing that gas will not cause it to liquefy no matter how high the pressure applied. (√) 58. The head of a centrifugal pump is equal to the lift height provided by the pump. (X) 59. The flow rate of a centrifugal pump decreases as the impeller diameter increases, and increases as the impeller speed increases. (X) 60. The effective power of the pump is equal to the power output by the motor. (X) 61. The reason why a centrifugal pump can draw liquid into the pump is that a vacuum is created at the center as the impeller rotates, which draws the liquid into the pump through the suction pipeline. (√) 62. Change the speed of the centrifugal pump. As the rotational speed increases, both the flow rate Q and the head H increase. (√) 63. The characteristic of centrifugal pumps operating in series is that the flow rate of each pump is equal, and the total head is equal to the sum of the heads of all the pumps. (√) 64. When two centrifugal pumps operate in series, their total flow rate is equal to the sum of the flow rates of the two pumps. (X) 65. The purpose of operating two centrifugal pumps in series is to increase the head. (√) 66. The purpose of operating centrifugal pumps in parallel is to increase flow rate. (√) 67. Before starting a reciprocating pump, the pump outlet valve must be opened, and a safety valve should be installed on the pump outlet pipeline, as the pressure generated by a reciprocating pump can increase indefinitely. (√) 68. The discharge flow rate of a reciprocating pump cannot be adjusted by changing the opening degree of the pump outlet valve. (√) 69. When a reciprocating pump is in operation, it discharges liquid periodically, but the flow rate is continuous. (X) 70. Excessively high lubricating oil temperature can cause a drop in the pressure of the lubricating oil system. (√) 71. At constant other conditions, in a centrifugal compressor, an increase in the molecular weight of the inlet gas leads to a corresponding increase in the outlet pressure. (√) 72. Whether the turbine blades are fouled can be determined by an increase in pressure inside the cylinder, an increase in the opening degree of the throttle valve with little change in speed, a decrease in the steam flow capacity, and a drop in output power. (√) 73. By connecting jet pumps in series, a higher vacuum level can be achieved. (√) 74. Too low a SS pressure is not good for the compressor, but a high pressure is not harmful. (X) 75. The operating point of a centrifugal pump is the intersection of the pump’s characteristic curve and the pipeline’s characteristic curve. (√) 76. The chemical properties of metal materials refer primarily to the material’s ability to resist oxidation or chemical attack by corrosive agents at normal or high temperatures. (√) 77. In addition to providing lubrication, lubricating oil can also serve to dissipate heat, prevent dust, resist rust, and absorb vibrations. (√) 78. When using an orifice plate to measure fluid flow, the greater the flow rate, the greater the pressure difference across the orifice plate. (√) 79. The viscosity of a liquid increases as pressure increases. (X) 80. Whether the turbine blades are fouled can be determined by an increase in pressure within the cylinder, an increase in the opening degree of the throttle valve with little change in speed, a decrease in the steam flow capacity, and a drop in output power. (√) 81. When a centrifugal pump is in operation, the blades of the impeller force the liquid to rotate, thereby generating centrifugal force. Under the effect of centrifugal force, the liquid is flung toward the outer edge of the impeller. The liquid gains energy in the impeller, its kinetic energy increases while its static pressure energy remains unchanged. (X) 82. The shaft power of a pump is the power obtained by the pump shaft from the motor; shaft power is always greater than the useful power. (√) 83. The purpose of operating centrifugal pumps in parallel is to increase head. (X) 84. The output pressure of a reciprocating pump can be infinitely high; the flow rate is independent of pressure, it has self-priming capability, and the flow rate is uneven. (√) 85. The flow rate of a reciprocating pump is related to the discharge pressure; the higher the pressure, the lower the flow rate. (X) 86. The flow rate of a reciprocating pump is related to the piston diameter, stroke, and number of reciprocations, and it is independent of the discharge pressure. (√) 87. Reciprocating pumps operate by changing the working volume. (√) 88. The pump outlet valve cannot be closed when the positive displacement pump is started. (√) 89. In a differential pressure gauge used for measuring liquid levels, the differential pressure range is determined by the density of the medium, and is independent of the density of the filling fluid. (√) 90. When a centrifugal compressor experiences surge, the larger the volume of the piping system, the smaller the surge amplitude ； The smaller the volume of the pipeline equipment, the greater the surge amplitude. (X) 91. Surge occurs in a centrifugal compressor only when the intersection point of its performance curve and that of the piping network lies within the surge boundary line. (√) 92. If the temperature of the ethylene refrigerant is reduced to 10°C, it cannot be liquefied no matter what pressure is applied. (√) 93. The discharge flow rate of a reciprocating pump cannot be adjusted by changing the opening degree of the pump outlet valve. (√) 94. The function of the lubricating oil system pressure reservoir is to ensure a reliable switching between the main oil pump and the auxiliary oil pump, preventing interlock actions caused by low pressure during the switching process. (√) 95. The seal oil system’s transfer diaphragm tank serves as a backup pressure oil tank for the seal oil. (√) 96. The conversion diaphragm oil tank in the seal oil system allows the seal oil and the sealing gas to be separated, thereby ensuring the quality of the seal oil. (√) 97. The oil/gas pressure difference of 0.035 MPa in the seal oil system is maintained constant by the seal oil pressure. (X) 98. When emptying the tower tank, relieve pressure first before draining the liquid. (X) 99. The more compressor stages there are, the higher the surge point. (√) 100. At a certain gas flow rate, in a centrifugal compressor, the rotational speed of the gas is always lower than the rotational speed of the impeller. (√) 101. In distillation operations, once the operating pressure and temperature are determined, the compositions at the top and bottom of the tower are also determined. (√) 102. The greater the gain of a proportional regulator, the smoother the transition process curve, but the larger the error margin. (√) 103. The smaller the gain of the proportional regulator, the more oscillatory the transition process curve becomes. Divergent oscillations may occur when the proportional gain is too low. (√) 104. The integral control action can eliminate deviations. (√) 105. The output variation of the integral control action is proportional to the integral of the input error; in other words, the rate of change of the integral output is proportional to the input error. P=K1∫edt. (√) 106. The differential regulation effect has the effect of suppressing oscillations. (√) 107. When using an orifice plate to measure fluid flow, the greater the flow rate, the greater the pressure difference across the orifice plate. (√) 108. When the regulation process is unstable, the integration time can be increased or the proportional gain can be raised to stabilize it. (√) 109. The residual of the proportional control process is proportional to the gain of the controller. (√) 110. The shaft power of a centrifugal pump varies with the density of the liquid being transported. (√) 111. Expansion refrigeration is a isentropic expansion process; since work is done during isentropic expansion, its cooling capacity is greater than that of isenthalpic expansion. (√) Practical Questions Section of the National Ethylene Competition Question Bank
I. Multiple-choice Questions (50 questions)
1. The following analysis of the high alkane content in propylene products is incorrect: (D)
A. Reduced purity of hydrogen used in the triple-carbon hydrogenation process
B. Less cracking gas being sent back to the cracking gas compressor from the methane stripping tower
C. Excessively low temperature control at the bottom of the deethanization tower
D. Insufficient heating in the propylene distillation tower

2. The following analysis of the reasons for poor performance in the dual-carbon hydrogenation process is incorrect: (B)
A. Insufficient temperature for the methanation reaction
B. Increased temperature in the reactor bed
C. Excessive amount of CO added
D. Substandard H2S removal during alkaline washing

3. Possible reasons for increased conductivity in the recombined water include: (B, D)
A. Large volume of recombined water
B. Damage to the tubes in the surface condenser
C. Excessive amount of BW added
D. Substandard quality of steam

4. If a cracking furnace is designed to operate for 320 days per year, with 20 days dedicated to maintenance due to coking, then its annual operating rate is: (B)
A. 90%
B. 94.1%
C. 98%
D. 96%

5. In reciprocating compressors, using multi-stage compression has many advantages. Which of the following statements is incorrect? (D)
A. It reduces the exhaust temperature.
B. Using 3–5 stages can save energy consumption during compression.
C. It can increase the volumetric efficiency.
D. It can reduce the clearance factor.

6. In the water washing section of the alkaline washing tower, to more effectively remove alkali from the cracking gas, it is advisable to use: (D)
A. Floating valve trays
B. Packed trays
C. Screen trays
D. Bubble trays

7. The following is not a method that can help reduce the energy consumption of a cracking furnace: (C)
A. Reducing idling time of fans
B. Reducing the amount of wastewater discharged from the drum and waste heat boiler
C. Lowering the pressure and temperature of the drum
D. Using more fuel oil and less C4 liquefied gas, while making full use of the plant’s fuel gas

8. The following statements are incorrect: (A, D)
A. At high cracking depths, coking in the cracking furnace tubes is a limiting factor for the operation cycle of the furnace. At high pyrolysis depths, coking in the quench boiler is a limiting factor for the operating cycle of the pyrolyzer. C If the cycle quench oil is operated at a lower viscosity, the heat recovery rate of the quench oil system can be improved. D If the circulating quench oil is operated at a lower temperature, the heat recovery rate of the quench oil system can be improved. 9. The reason for high ethylene content in the bottom of the ethylene distillation tower may be (A). A. The propylene refrigerant contains light components. B. The feed rate to the ethane furnace is low. C. The cracking depth in the ethane furnace is low. D. The pressure in the propylene suction tank at 3°C is high.
10. Among the various sulfurizing agents listed below, the one that cannot be directly injected into the ethane furnace using a sulfur injection pump is (B). A. Dimethyldisulfide. B. Dimethyl sulfide. C. Carbon disulfide. D. Thiol.
11. The reason for an excessively high dry point of cracked gasoline may be (A, D). A. The recycle rate of gasoline is too low. B. The amount of dilution steam used in the cracking furnace is too low. C. The amount of product taken from the side stream of the gasoline distillation tower is too high. D. The temperature at the top of the gasoline distillation tower is high.
12. The reason for an excessively low flash point of cracked light oil may be (B, C). A. The recycle rate of gasoline is too low. B. The cracking depth is low. C. The stripping temperature in the stripping tower is insufficient. D. The temperature at the top of the gasoline distillation tower is high.
13. The reason why the quench oil circulation pump does not operate properly may be (A, B, D). A. The inlet filter is clogged. B. The seal oil of the pump contains water. C. The viscosity of the quench oil is too high. D. The internal components of the tower block the pump’s inlet.
14. When the temperature at the bottom of the ethylene distillation tower is too low, the ethane furnace should (D). A. Increase the conversion rate of ethane. B. Raise the cracking temperature in the ethane furnace. C. Increase the feed rate to the ethane furnace. D. Increase the amount of dilution steam used to raise the water-to-oil ratio.
15. During an emergency shutdown of the cracking furnace, the cooling rate should be controlled at (B)°C. A. <50°C. B. 50–70°C. C. Around 100°C. D. <150°C.
16. When heating the cracking furnace up, the heating rate should be kept at no more than (A)°C. A. 30. B. 50. C. 70. D. 100.
17. Among the raw materials listed below, (A) has its cracking furnace operation cycle primarily determined by the exit temperature and pressure drop of the quench boiler. A Light diesel B Ethane C Propane D Oil field gas 18. The possible reasons for the high liquid level in the suction tank of the pyrolysis gas compressor are (AC). A Sudden decrease in pyrolysis depth B Excessively high temperature between sections C Change in the composition of the pyrolysis gas toward heavier components D Too low control of the top temperature in the quench tower 19. When the oxygen content is too high, it is necessary to (A) adjust the bottom air valves and (B) adjust the side wall burners. A Reduce the air valve opening B Increase the fuel supply C Reduce the fuel supply 20. If there are large differences in the outlet temperatures of the four groups in a furnace, or if the opening degrees of the feed control valves for these groups differ significantly even when the temperatures are adjusted uniformly, the possible reasons are (B C). A Excessive air supply B Inaccurate inlet flow meters C Clogged burners D Too small opening degrees of the air valves for each burner group 21. Factors that cause fluctuations in the furnace’s outlet temperature include (AB). A Fluctuations in raw material pressure B Unstable DS pressure C Excessively high fuel pressure D Excessively low negative pressure in the furnace chamber 22. To ensure safety, the concentrations of acetylene and methylene in the liquid at the bottom of the propylene tower must not exceed (C). For use as household liquefied gas, the acetylene content should be below ( ). A 40% 10% B 20% 10% C 40% 2% D 20% 2% 23. The cross-temperature in a pyrolysis furnace is determined by (A), and generally, the allowable fluctuation range for this cross-temperature is (A)°C. A Characteristics of the feedstock for cracking: ±10; B Preheating temperature of the material: ±20; C Temperature at the furnace outlet: ±10; D Flue gas temperature: ±20. 24. During the regeneration of the catalyst in the carbon dioxide hydrogenation reactor, air combustion is stopped when the CO2 content in the regeneration gas is equal to or less than (2)% and the O2 content is equal to or greater than (15)%. A CO2 5%, O2 5% B CO2 2%, O2 10% C CO2 2%, O2 15% D CO2 6%, O2 12% 25. The purpose of limiting the boiler feedwater in a pyrolysis furnace is (B). A Ensures continuous drainage; B Prevents interruption in the BW tubes of the drum; C Required for waste discharge. 26. Possible reasons for high pressure in the ethylene distillation tower are (A, D): A Poisoning of the carbon dioxide hydrogenation catalyst; B Excessively high temperature at the bottom of the demethanization tower; C Low liquid level in the intermediate boiler; D High condensation temperature at the tower top and high reflux temperature. 27. Which of the following phenomena is not indicative of a rupture in the BW tubes in the convection section? (B) A. The water supply to boiler A increases; B. The flue gas temperature rises; C. White smoke is emitted from the flue; D. The furnace wall panels in the convection section are damaged by the impact and produce loud noises. 28. The reason for flame fluctuation when the cracking furnace operates on oil is not (B): A. Unstable fuel oil pressure; B. Excessive air volume; C. Unstable furnace pressure; D. Insufficient atomizing steam. 29. The feed rate of ethane as raw material is 1000 kg/h, the amount of ethane that reacts is 600 kg/h, and 340 kg/h of ethylene is produced; thus, the reaction selectivity is (C): A. 70.6%; B. 60.5%; C. 60.7%; D. 70.5%. 30. The function of the bypass line (hot line) for the fifth-stage water cooler in the GB-201 system is (A). A Increase the temperature of the gas from the \"five returns and four exits\" process; B Use the bypass line when the heat exchanger is blocked; C Use the bypass line when the load increases. 31. The gas phase from the oil-gas separator should be sent to (A) at the beginning of operation. A Torch line B FA-201 C Direct venting 32. The butter in the caustic scrubber bottom comes from (A). A. Condensation and polymerization of hydrocarbons B. Carried in with the pyrolysis gas C. Products of reaction with alkalis. 33. The reason for the high temperature in the cross-section of the furnace is (C). A Positive pressure in the furnace chamber B Insufficient air C Excessive air D Too large a flame 34. The reason for an overly long flame is (A). A Excess primary air B Excess secondary air C Insufficient air D Clogged burner 35. For an ethylene distillation column, which of the following statements is incorrect? (C) A The relative volatility of ethylene to ethane increases as pressure decreases ； B. At the same pressure, the relative volatility of ethylene compared to ethane increases as the temperature rises. C. At the same pressure, the relative volatility of ethylene compared to ethane increases as the ethylene concentration rises. D. Ethylene is used as a coolant at the top of low-pressure ethylene distillation towers, whereas it is not required in high-pressure ethylene distillation towers. 36. The GB-201N compressor requires that the minimum flow rate at the inlet of each stage shall not be less than (C)% of the design flow rate; otherwise, the compressor may experience surge. A 60 B 70 C 80 37. The purpose of rotating the turbine compressor immediately after it is shut down is (A). A. Avoid bending and deformation of the rotor. B. Accelerate the cooling of the machine body. C. Inspect the compressor. 38. Regarding the propylene distillation tower, which of the following statements is incorrect? (D) A. If low-pressure methods are used for propylene distillation, heat pump systems are generally employed ； In ethylene plants, the propylene column is the column with the highest number of trays ； In the early stages of operation, distillation can be used to remove propyne and acrylene, but there is significant loss of propylene at the bottom of the tower ； In distillate oil cracking units, a low-pressure propylene distillation process is used, which is simple and reduces investment costs ； 39. Regarding the operation of a distillation column, which of the following statements is correct? (B) A For a distillation column operating at full capacity, increasing the reflux ratio will definitely improve the separation efficiency ； In Column B, as the feed rate increases while the draw rate remains unchanged, the upward steam velocity rises and the pressure difference across the column increases; in severe cases, this can lead to flooding ； C When the feed to the distillation column remains constant while the amount taken from the top of the column increases, the reflux ratio must increase as well ； After the composition of feed D becomes lighter, the position of the feed inlet should be lowered to improve separation efficiency ； 40. The reason why the pressure difference in the distillation column increases, and this difference does not decrease even after taking measures such as increasing the amount taken from the column top, reducing the reflux rate, and lowering the temperature of the reactor, is that the column has experienced (C). A Liquid overflow B Flood tower C Freezing tower 41. The possible reasons for unsatisfactory drying of pyrolysis gas are (A B C D). A Leakage in the high-pressure methane heating heat exchanger B High temperature at the exit of the fifth stage of the pyrolysis gas compressor C Insufficient regeneration temperature or too short holding time D Flow imbalance inside the dryer 42. The purpose of injecting flushing oil at the inlet of each stage of the pyrolysis gas compressor is (D). A. Lubrication B. Rust removal C. Removal of heavy components D. Prevention of scaling. 43. The oil filter differential pressure needs to be replaced when it is greater than or equal to (B) MPa. A 0.05 B 0.035 C 0.1 D 0.2 44. The maximum emission level of a flare is generally determined based on the total emissions during an accident scenario (B). A: Top of the quench tower + ethylene compressor B: Top of the quench tower + propylene compressor C: Top of the ethylene distillation column + propylene distillation column D: Top of the ethylene distillation column + propylene refrigeration compressor. 45. Compressing the pyrolysis gas may (D) A. Reduce power consumption B. Increase the relative volatility of hydrocarbons C. Lower the operating temperature for deep cryogenic separation D. Reduce the burden of drying and dehydration. 46. When pre-cooling a spherical tank, it is required that the temperature difference between the top and bottom of the tank be no more than (C)°C. A 20 B 50 C 40 D 10 47. The reasons for the high temperature at the methanation outlet are (A, B). A High ethylene content in crude hydrogen B High CO content in crude hydrogen C High CH4 content in crude hydrogen 48. Excessively high ethylene content in the feed to the methanation reactor will lead to (B). A Catalyst poisoning B Overheating C No reaction with CO 49. The temperature of the ethylene refrigeration compressor unit can be considered satisfactory for pre-cooling when it is below (B) °C. A -40 B -20 C -30 50. The operating pressure of the pressure vessel is P, and water is used as the pressurizing medium. Then the pressure rating for the container’s pressure test is (A). A 1.25P B 1.15P C 1.10P II. True or False Questions (50 questions) 1. The partial pressure of acetylene is related to the amount of green oil produced; it affects the catalyst regeneration cycle, but does not directly influence the catalyst’s activity. (Yes) 1. When the hydrogen-to-acetylene ratio is too high, the excess hydrogen causes ethylene to be hydrogenated into ethane, resulting in a loss of ethylene product; at the same time, the amount of green oil increases, which affects the catalyst’s activity. (Yes) 2. The purpose of designing a side stream for ethylene extraction in Tower DA-402 is to reduce the ethane content in the ethylene. (Incorrect) 3. Increasing the operating pressure of the propylene distillation column can increase the relative volatility of propylene and propane. At the same time, improve the operating capacity of the propylene tower. (Incorrect) 4. At room temperature, throttling all gases will result in a decrease in temperature after throttling. (Incorrect) 5. The liquid-phase catalytic hydrogenation process makes it easy to control the temperature of the reaction bed. Thereby extending the catalyst's service life and increasing the propylene yield. (Yes) 6. The relative volatility of propylene and propane is close, so the propylene distillation column requires the greatest number of trays. (Yes) 7. The low-molecular-weight polymers resulting from the dimerization and trimerization of ethylene and acetylene during the hydrogenation of acetylene are brownish-green, transparent oily substances, known as \"green oil\". (Yes) 8. In catalytic hydrogenation reactions, it is known from thermodynamics that the equilibrium constant decreases as the temperature rises; therefore, to ensure that the reaction proceeds completely, the reaction temperature should be kept as low as possible. (Yes) 9. In distillation operations, to ensure the quality of the product at the top of the tower, the reflux ratio can be increased indefinitely. (Incorrect) 10. The value of the reflux ratio plays an important role in the design of the number of trays in the distillation column and the feeding position. (Yes) 11. According to the principle of phase equilibrium, the temperature of each tray in a distillation column reflects the composition of that tray; an increase in temperature indicates that the components are becoming heavier. (Yes) 12. At low temperatures, trace amounts of water can form white crystalline hydrates with hydrocarbons, and the higher the pressure, the higher the temperature at which hydrates begin to form. (Yes) 13. Based on the different distillation methods, they can be divided into three categories: simple distillation, fractional distillation, and special fractional distillation. (Yes) 14. The purpose of cold blowing during the dryer regeneration step is to desorb the fluid vapor using methane. (Yes) 15. The level of the inlet temperature of the pyrolysis gas dryer does not affect whether the moisture content at the dryer’s outlet is within acceptable limits. (Incorrect) 16. While driving, leaks at locations such as flanges must be prevented during the pre-cooling and cooling of the cooling system. (Yes) 17. The reflux ratio of the low-pressure demethanizer is much higher than that of the high-pressure demethanizer; therefore, the low-pressure process is more energy-intensive. (Incorrect) 18. As an adsorbent, molecular sieves can selectively adsorb molecules based on their degree of unsaturation; the higher the degree of unsaturation, the more molecules will be adsorbed. (Yes) 19. If the bed temperature of the methanation reactor increases, it is necessary to check whether there are any changes in the CO concentration and ethylene concentration in the feed crude hydrogen. (Yes) 20. The function of the demethanizer is to separate methane and components lighter than methane from components that are heavier than carbon dioxide. (Yes) 21. The function of the dryer is to remove water vapor from the pyrolysis gas. Dehydration is necessary to prevent the formation of ice and hydrates in the cooling equipment of the quenching sequence, cold boxes, and demethanization towers. (Yes) 22. When starting up, the pyrolysis gas compressor uses its own gas from the fourth stage outlet as the sealing gas; once normal operation is achieved, dried pyrolysis gas or high-pressure ethylene gas from FA209 can be used as the sealing gas. (Yes) 23. High-pressure demethanization achieves a higher separation efficiency than low-pressure demethanization columns. (Wrong) 24. The purpose of filling the steel shell of the refrigerator with nitrogen is to prevent moist air from entering. (Yes) 25. After an emergency shutdown of the plant, the various dryers should be taken out of service as soon as possible. Ensure that a dryer is available for use while driving without the need for regeneration (Correct). 26. If secondary reactions of ethylene such as polymerization or decomposition have already begun, reducing the amount of hydrogen can prevent the temperature from getting out of control. (Incorrect) 27. In the acetylene hydrogenation reaction, higher reaction temperatures increase catalyst activity but reduce selectivity. (Yes) 28. The liquid discharge system LD discharges the low-temperature liquids from the low-temperature and cryogenic sections of the unit into the wet flare tank. (Incorrect) 29. There are two types of uncontrolled reactions that can occur in acetylene reactors; the reactions that lead to an increase in temperature are both exothermic reactions. One of them is the hydrogenation of ethylene in the presence of excess hydrogen, and the other is the polymerization-degradation of ethylene. (Yes) 30. The methane in the ethylene distillation column comes from the bottom liquid of the demethanization tower and the hydrogen feed to the acetylene converter. (Yes) 31. The adsorption capacity of molecular sieves increases as the temperature rises. (Wrong) 32. The reason for QW emulsification is too high a temperature of QW, the infiltration of light diesel into gasoline, or too high a pH value of QW. (Yes) 33. From the perspective of raising the temperature at the bottom of the gasoline distillation column and increasing the yield of QO, it is advisable to increase the amount taken out via side streams. (Incorrect) 34. The lower the diluted vapor pressure, the more heat can be extracted from the quench oil, and the lower the viscosity of the quench oil. (Yes) 35. Adding pyrolyzed light diesel to the bottom of the gasoline distillation column is one of the main methods for controlling the viscosity of the quench oil, but this leads to higher temperatures at the top of the DA-101N column as well as on each column tray. (Yes) 36. In binary-component distillation, when two of the parameters—temperature, pressure, and composition—are determined, the third parameter is also determined accordingly. (Yes) 37. The three main factors affecting the separation of methane and ethylene are separation temperature, pressure, and the molar ratio of methane to hydrogen; the smaller the molar ratio of hydrogen to methane, the greater the loss of ethylene. (Incorrect) 38. A notable characteristic of centrifugal compressors is that their volumetric flow rate has a definite relationship with the increase in energy head of the gas as it passes through the compressor. (Yes) 39. The main failures caused by unstable quality of circulating water include scaling, corrosion, biological issues, and sludge problems. (Yes) 40. Static electricity is primarily generated by friction, and its characteristic is that the static voltage is not high. (Incorrect) 41. Among the three cracking feedstocks—ethane, propane, and butane—butane yields the highest amount of propylene. (Incorrect) 42. The pyrolyzer with the shortest residence time in use today is the millisecond furnace, whose residence time can be less than 0.1 seconds. (Yes) 43. The separation yield is primarily influenced by the separation process; if a post-hydrogenation process is used, the ethylene yield will increase significantly. (Incorrect) 44. If the temperature of the acetylene hydrogenation reaction is not controlled and a spike in temperature occurs, a non-contact exothermic reaction takes place at 400°C; if this is also not controlled, a decomposition reaction will occur. (Incorrect) 45. The relative volatility of propyne compared to propane changes with the concentration of propylene; when the propylene concentration is low, the relative volatility of propyne is higher than that of propane. (Yes) 46. The methanation reaction is an exothermic reaction with a decrease in the number of molecules; from the perspective of chemical equilibrium, increasing the reaction temperature facilitates its progress. (Incorrect) 47. After methanation, hydrogen must be dried to remove the water produced by the reaction; otherwise, it cannot be supplied to various users for hydrogenation reactions. (Incorrect) 48. Catalysts for methanation reactions generally use Pd as the active center; such catalysts not only accelerate the methanation reaction but also speed up the hydrogenation of unsaturated hydrocarbons, so it is necessary to control the ethylene content in the hydrogen gas. (Incorrect) 49. In an ethylene distillation column, when the column pressure is constant, temperature and composition are interdependent; composition and temperature have a linear relationship. (Yes) 50. Above 9.5°C, ethylene cannot be turned into a liquid no matter what pressure is applied. (Yes) 51. During propane cracking, the cracking gas can be directly cooled down by rapid water quenching. (Yes) 52. The characteristic factor K for cracking feedstocks is lowest for alkanes, next for naphthenes, and highest for aromatics. (Incorrect) 53. The characteristic factor K for cracking feedstocks; the higher the K value, the stronger the paraffinic nature ； The lower the K value, the stronger the aromaticity (correct). 54. The carbon-to-hydrogen ratio of the feedstock for cracking refers to the ratio of the number of carbon atoms to the number of hydrogen atoms in the hydrocarbons. (Incorrect) 55. At high pyrolysis depths, coking in the pyrolysis furnace tubes is a limiting factor for the operation cycle of the pyrolysis furnace. (Incorrect) 56. At high pyrolysis depths, coking in the quench boiler is a limiting factor for the operating cycle of the pyrolyzer. (Yes) 57. If the circulating quench oil is operated at a lower viscosity, the heat recovery rate of the quench oil system can be improved. (Yes) 58. If the circulating quench oil is operated at a lower temperature, the heat recovery rate of the quench oil system can be improved. (Incorrect) 59. Compared to the use of floating valve trays, high-efficiency packing in gasoline distillation columns allows for a reduction in the hydrocarbon partial pressure during the pyrolysis reaction, while keeping the inlet pressure of the pyrolysis gas compressor constant, thereby increasing the selectivity of the pyrolysis reaction. (Yes) 60. The higher the outlet pressure of the pyrolysis gas compressor, the more favorable it is for the separation of methane and ethylene in the subsequent system. (Incorrect) 61. During the regeneration of molecular sieves, a certain amount of superheated steam can be introduced first, followed by methane-hydrogen regeneration gas, with gradual heating to the regeneration temperature. (Yes) 62. The higher the overall compression ratio of the compressor, the more power can be saved by using intercooling. (Yes) 63. Pyrolysis gas compression is an ideal compression process, that is, a polytropic or adiabatic compression process. (Incorrect) 64. Theoretically, increasing the number of compression stages in the pyrolysis gas stream and implementing inter-stage cooling (which reduces the degree of irreversibility in the compression process, bringing it closer to an isothermal compression process; the more stages there are, the closer this becomes) can help reduce power consumption. (Yes) 65. For certain pyrolysis feedstocks, the content of alkynes decreases as the degree of pyrolysis increases. (Incorrect) 66. At the same cleavage depth, operating conditions with high temperature and short residence time will produce more alkynes. (Yes) 67. A high DS flow rate can lead to low ethylene yield, rapid coking of the furnace tubes, and a shortened operating cycle of the cracking furnace. (Yes)