The most important use of diesel oil is for diesel engines of vehicles and ships.Compared with gasoline engines, diesel engines have high thermal efficiency and low fuel consumption.Diesel has low energy consumption, so some small cars and even high-performance cars also use diesel.
On October 27, 2017, the list of carcinogens released by the International Agency for Research on Cancer of the World Health Organization (WHO) was preliminarily sorted out for reference. Diesel oil and light distillates were included in the list of three types of carcinogens.[1]
Light petroleum products are complex hydrocarbon mixtures with about 10-22 carbon atoms.It is the fuel of compression ignition engine (i.e. diesel engine).
It is mainly composed of diesel oil fractions produced by crude oil distillation, catalytic cracking, thermal cracking, hydrocracking, petroleum coking and other processes (it also needs to be refined and added with additives);It is made from crude oil, shale oil, etc. through straight distillation or cracking.According to the nature of crude oil, there are paraffin based diesel oil, naphthenic based diesel oil, naphthenic aromatic based diesel oil, etc.
Calorific value is 3.3 × 10sevenJ/L。
Liquid petroleum fraction with boiling point range and viscosity between kerosene and lubricating oil.Flammable and volatile, insoluble in water, soluble in alcohol and other organic solvents.It is a mixture with complex components, with boiling points ranging from 180 ℃ to 370 ℃ and 350 ℃ to 410 ℃.
Liquid petroleum fraction with boiling point range and viscosity between kerosene and lubricating oil.
The main indicators are cetane number, viscosity, freezing point, etc.The requirements for diesel quality are good combustion performance and fluidity.The higher the cetane number, the better the combustion performance. The cetane number of diesel oil made from Daqing crude oil can reach 68.The cetane number of light diesel oil for high-speed diesel engines is 42 〜 55, and that for low-speed diesel engines is below 35.
classification
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According to the different density, for petroleum and its processed products, it is customary to call those with low boiling point or boiling range light, on the contrary, they become heavy.It is generally divided into light diesel oil and heavy diesel oil.
Diesel oil is divided into light diesel oil (boiling point range is about 180-370 ℃) and heavy diesel oil (boiling point range is about 350-410 ℃).The most important performance of diesel fuel is its ignitability and fluidity. Its technical indicators are cetane number and freezing point respectively. The current specification of diesel fuel in China requires that the sulfur content be controlled within 0.5% - 1.5%.
Like gasoline, diesel has different brands.
Diesel oil is classified according to solidification point. Light diesel oil has six brands of 5, 0, - 10, - 20, - 35 and - 50, and heavy diesel oil has three brands of 10, 20 and 30.
The selection of diesel oil is based on the temperature during use.The last five brands of diesel are mainly used for diesel vehicles, and 0 # diesel is used when the temperature is above 4 ℃;- 10 # diesel oil is selected when the temperature is 4 ℃~- 5 ℃;- 20 # diesel oil is selected when the temperature is - 5 ℃~- 14 ℃;- 35 # diesel oil is selected when the temperature is between - 14 ℃ and - 29 ℃;If the brand of diesel fuel is higher than the above temperature, the fuel system in the engine may be waxed, blocking the oil path, and affecting the normal operation of the engine.
purpose
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High speed diesel engines (for automobiles) save more fuel than gasoline engines, and the growth rate of diesel demand is faster than that of gasoline.
Compared with gasoline engines, diesel engines have higher thermal efficiency, higher power, lower fuel consumption and are more economical, so they are increasingly widely used.
As the fuel consumption of high-speed diesel engines (50-75g/MJ) is lower than that of gasoline engines (75-100g/MJ), the number of large vehicles using diesel engines is increasing.Diesel oil is widely used in large vehicles, railway locomotives and ships.It is mainly used as the liquid fuel of diesel engines. Diesel has the environmental protection characteristics of low energy consumption and low pollution, so some small cars and even high-performance cars also use diesel.
It is mainly used as the power of tractors, large automobiles, diesel locomotives and civil engineering, excavators, loaders, fishing boats, diesel generator sets and agricultural machinery. It is the diesel engine fuel of diesel automobiles, tractors and other diesel engines.
Price adjustment
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On November 7, 2023, the National Development and Reform Commission released the news that, according to the recent changes in the international market oil prices and the current oil product price formation mechanism, the domestic diesel price will be reduced by 135 yuan per ton from 24:00 on November 7, 2023.[2]
From 24:00 on December 19, the domestic diesel will be reduced by 400 yuan per ton.[3]
From 24:00 on April 1, 2024, the price of domestic gasoline and diesel will increase by 200 yuan and 190 yuan per ton respectively.[4]
Parameters and measurement
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Oxidizability
Determine according to SH/T0175 method.
Method summary: Inject 350mL filtered sample into the oxidation tube, inject oxygen, and oxidize it for 16h at 93 ℃ at a rate of 50mL/min.Then cool the oxidized sample to room temperature and filter the filterable insoluble matter.The adhesive insoluble matter is obtained by washing the adhesive insoluble matter from the oxidation tube with three agents and evaporating the three agents.The sum of the amount of filterable insoluble matter and adhesive insoluble matter is the total amount of insoluble matter.
Sulfur content
Determine according to GB/T 380.
Method outline: Burn an appropriate amount of sample in a lamp, absorb sulfur dioxide generated by combustion with 0.3% sodium carbonate aqueous solution, titrate the absorption solution with 0.05N hydrochloric acid standard solution, and use bromocresol green methyl red as titration indicator.
acidity
Determine according to GB/T 258.
Method outline: Volumetric method, this method uses boiling ethanol to extract organic acid from light diesel oil, and then titrate it with 0.05N potassium hydroxide ethanol solution while hot, and neutralize milliliters of potassium hydroxide required for 100ml petroleum products, which is called acidity.
Carbon residue
Determine according to GB/T 268.
Method outline: Put an appropriate amount of sample in the crucible for decomposition distillation, and the residue will undergo cracking and coking reaction after intense heating. After heating for 30 ± 2 minutes, calculate the carbon residue value according to the mass of carbon residue.
ash content
Determine according to GB/T 508.
Method outline: Put the sample of no more than 100g in a crucible with constant weight, heat it with a hot plate, use ashless filter paper as the ignition core, burn it to only ash and carbon residue, and then place it in a 775 ± 25 ℃ high-temperature furnace for 1.5-2 hours, and obtain the ash content result by weighing.
flash point
Determine according to GB/T 261.
Method outline: The sample is heated at a very slow and constant rate under continuous stirring.At the specified temperature interval, a small flame is introduced into the cup when mixing is interrupted.The lowest temperature when the test flame causes steam flash on the sample is taken as the flash point.10. The closed flash point of No. 5, 0, - 10 and - 20 diesel fuel is 50 ℃, and that of No. 35 and - 50 diesel fuel is 45 ℃.
density
Determine according to GB/T 1884 and GB/T 1885.
The density of No. 0 diesel oil is at the standard temperature of 20 ℃, generally 0.84--0.86g/cm³between.
Method summary: Keep the sample at the specified temperature, pour it into the density measuring cylinder with approximately the same temperature, put the appropriate density meter into the sample with adjusted temperature, and let it stand still.When the temperature reaches equilibrium, read the densimeter reading and the sample temperature.Convert the observed densimeter reading to standard density with a petroleum meter.
Freezing point
Determine according to GB/T 510.
Solidification point is an important index to evaluate the fluidity of diesel oil, which represents the lowest temperature at which fuel can be transported without heating.The freezing point of diesel oil refers to the maximum temperature when the oil is cooled to the point where it loses its fluidity under specified conditions.When there are more n-alkanes in diesel and the boiling point is high, the freezing point is also high.Generally, the freezing point of diesel oil is 3 ℃~5 ℃ lower than the ambient temperature. Therefore, different brands of commercial diesel oil with different freezing points need to be used according to seasonal and regional changes.In actual use, diesel will precipitate crystals at low temperatures, and when the crystals grow to a certain extent, the filter screen will be blocked. The temperature at this time is called cold filter plugging point.Compared with freezing point, it can better reflect the actual use performance.For the same oil product, the cold filter point is generally 1 ℃~3 ℃ higher than the freezing point.Low pour point diesel oil can be obtained by dewaxing.
Ignitability
(Cetane number)
High speed diesel engines require that diesel fuel be injected into the combustion chamber to quickly form a uniform mixture with air, and immediately ignite and burn automatically, so the fuel is required to be easy to self ignite.The time interval from the start of fuel injection into the cylinder to the start of ignition is called the ignition delay period or late ignition.If the autoignition point (the temperature that can automatically ignite in the presence of air) of the fuel is low, the ignition delay period is short, that is, the ignition performance is good.
High speed diesel engines require that diesel fuel be injected into the combustion chamber to quickly form a uniform mixture with air, and immediately ignite and burn automatically, so the fuel is required to be easy to self ignite.The time interval from the start of fuel injection into the cylinder to the start of ignition is called the ignition delay period or late ignition.If the autoignition point (the temperature that can automatically ignite in the presence of air) of the fuel is low, the ignition delay period is short, that is, the ignition performance is good.Cetane number is generally used as an index to evaluate the spontaneous combustion of diesel fuel.
Cetane number refers to the volume percentage of normal hexadecane contained in the standard fuel that is equivalent to the measured diesel fuel's self ignitability.Determine according to the method in GB/T 386.The standard fuel is n-hexadecane andαThe mixture of methyl naphthalene prepared according to different volume percentages, in which n-hexadecane has good spontaneous combustion property, and its cetane number is specified as 100,α-Methylnaphthalene has poor self ignition property, and its cetane number is specified as 0.It is also replaced by 2, 2, 4, 4, 6, 8, 8-heptamethylnonaneα-The cetane number of methyl naphthalene (1-methylnaphthalene) is set to 15, and the cetane number is measured on the laboratory standard single cylinder diesel engine according to the specified conditions.
Cetane number was measured on a laboratory standard single cylinder diesel engine under specified conditions.Diesel fuel with high cetane number is easy to start, has uniform combustion and high output power;If the cetane number is low, the ignition is slow, the operation is unstable, and the knock is easy to occur. Generally, light diesel oil used for high-speed diesel engines should have a cetane number of 40-55;The cetane number of heavy diesel oil for medium and low speed diesel engines can be as low as 35.The cetane number of diesel oil is related to its chemical composition: the cetane number of normal paraffin is the highest;The cetane number of aromatic hydrocarbon is the lowest;Isomers and cycloalkanes are in the middle.Most of China's diesel oil comes from paraffin based crude oil (such as Daqing crude oil), which contains more alkanes, so its cetane number is high;The cetane number of Daqing straight run diesel oil is as high as 68, but the cetane number of the diesel oil fraction obtained through catalytic cracking is below 40.The cetane number of diesel can be increased by adding additives, such as amyl nitrate or ethyl ester.The ignitability of diesel fuel can also be expressed by diesel fuel index, which is calculated by the aniline point and relative density of diesel fuel according to the formula.Another method to characterize the ignitability of diesel fuel is the cetane index, which is calculated from the relative density and 50% distillation temperature according to the specified formula.
mobility
Solidification point is an important index to evaluate the fluidity of diesel oil, which represents the lowest temperature at which fuel can be transported without heating.The freezing point of diesel oil refers to the maximum temperature when the oil is cooled to the point where it loses its fluidity under specified conditions.
When there are more n-alkanes in diesel and the boiling point is high, the freezing point is also high.Generally, diesel oil is selected, and the freezing point is required to be 3~5 ℃ lower than the ambient temperature.Therefore, with the change of seasons and regions, commercial diesel oil of different brands (different solidification points) can be used.In actual use, diesel will precipitate crystals at low temperatures, and when the crystals grow to a certain extent, the filter screen will be blocked. The temperature at this time is called cold filter plugging point.Compared with freezing point, it can better reflect the actual use performance.For the same oil product, the cold filter point is generally 1~3 ℃ higher than the freezing point.Low pour point diesel oil can be obtained by dewaxing.
copper corrosion
Determine according to GB/T 5096.
Method outline: immerse a polished copper sheet in a certain amount of sample, heat it to the specified temperature according to the product standard requirements, and keep it for a certain time.At the end of the test cycle, take out the copper strip and compare it with the corrosion standard color plate after washing to determine the corrosion level.
water content
Determine according to GB/T 260.
Method summary: Mix a certain amount of sample with 100mL of anhydrous solvent and distill it for no more than 1 hour. Calculate the sample moisture according to the volume of water collected in the receiver.
Mechanical impurities
Determine according to GB/T 511.
Method outline: Dissolve a certain amount of sample in an appropriate amount of warm solvent oil, filter it with a constant weight filter, and calculate the mechanical impurity content of the sample by weighing the impurities left on the filter.
Storage and use
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1. Prevent moisture and mechanical impurities from entering.
2. It is strictly prohibited to mix it with gasoline for lighting or as fuel for kerosene furnace.
3. Diesel must be precipitated, filtered, and impurities and moisture removed before use to ensure the normal operation of the diesel fuel supply system.
4. At low temperature, in order to improve the low-temperature fluidity of diesel oil, it is allowed to infiltrate a small amount of kerosene into diesel oil, but the flash point may be unqualified.However, it is never allowed to add gasoline to diesel oil to improve its low-temperature fluidity.
5. Diesel fuel of the same grade and different grades has basically the same quality index except freezing point and cold filter point, so when the resources are insufficient, it can be mixed under the condition of appropriate temperature.
6. Strictly prevent exposure to the sun and heating by open fire, and store at a lower temperature as far as possible.When using diesel in winter, necessary preheating can be carried out.
Toxicity and hazard
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The route of invasion of this product to human body: mainly through skin absorption and respiratory tract inhalation.
The toxicity of diesel oil is similar to that of kerosene, but due to the influence of additives (such as sulfide esters), the toxicity may be slightly greater than that of kerosene.
It mainly has anesthetic and irritant effects.There is no report of occupational poisoning.
Toxicity and health effects: diesel oil is a high boiling point component, so there is little chance of toxicity caused by steam during use.Inhalation of diesel droplets may cause inhalation pneumonia.Contact dermatitis may be caused by skin contact with diesel oil.It is mainly found in hands, wrists and forearms.Diesel exhaust gas, the exhaust gas produced by diesel combustion in internal combustion engines can often seriously pollute the environment.The exhaust gas contains nitrogen oxides, carbon monoxide, carbon dioxide, aldehydes and a large amount of black smoke during incomplete combustion.The black smoke contains unburned oil mist, carbon particles, some high boiling heterocycles and aromatics, and some carcinogens such as 3.4 benzopyrene.
Prevention method: strictly follow the operating procedures, correctly use personal protective equipment, and do not block the oil pipe with mouth suction.Shower and change clothes after work, and keep good hygiene habits.
Compared with gasoline, diesel contains more impurities, and it is more likely to produce smoke and dust when burning, causing air pollution.Soot generated after diesel combustion may cause cancer, so in recent years, diesel burning machines in Western European countries, including automobiles, must be equipped with dust filters before use.In order to reduce the pollution caused by smoke and dust, the sulfur oxides (SOx）Pollution is also a problem.
Diesel engine
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Diesel engine is an internal combustion engine that uses diesel as fuel.Diesel engine belongs to compression ignition engine, and it is often called Diesel Engine after the name of the main inventor, Diesel Engine.
When the diesel engine is working, the air sucked into the cylinder of the diesel engine is compressed to a higher degree due to the movement of the piston, reaching a high temperature of 500~700 ℃.Then the fuel is sprayed into the high-temperature air in the form of mist, and mixed with the high-temperature air to form a combustible mixture, which ignites automatically.The energy released during combustion acts on the top surface of the piston, pushing the piston and converting it into rotating mechanical work through the connecting rod and crankshaft.
classification
Diesel engines can be classified according to different characteristics: high-speed, medium speed and low-speed diesel engines according to speed;According to the type of combustion chamber, diesel engines can be divided into direct injection type, swirl chamber type and precombustion chamber type;According to the cylinder intake mode, it can be divided into supercharged and non supercharged diesel engines;According to the action mode of gas pressure, it can be divided into single acting, double acting and opposed piston diesel engines;It can be divided into marine diesel engine, locomotive diesel engine, etc.
There are many types of diesel engines:
① According to the working cycle, it can be divided into four stroke and two stroke diesel engines.
② According to the cooling mode, it can be divided into water cooled and air cooled diesel engines.
③ According to the air intake mode, it can be divided into supercharged and non supercharged (naturally aspirated) diesel engines.
④ According to the speed, it can be divided into high-speed (more than 1000 rpm), medium speed (350~1000 rpm) and low-speed (less than 350 rpm) diesel engines.
⑤ According to combustion chamber, diesel engines can be divided into direct injection type, swirl chamber type and precombustion chamber type.
⑥ According to the action mode of gas pressure, it can be divided into single acting, double acting and opposed piston diesel engines.
⑦ According to the number of cylinders, it can be divided into single cylinder and multi cylinder diesel engines.
⑧ It can be divided into marine diesel engine, locomotive diesel engine, automobile diesel engine, power generation diesel engine, agricultural diesel engine, engineering machinery diesel engine, etc.
Fuel
Diesel engine fuel is mainly diesel oil, usually light diesel oil is used for high-speed diesel engines;Light diesel oil or heavy diesel oil is used for medium and low speed diesel engines.The diesel engine uses the fuel injection pump and injector to inject fuel into the cylinder at high pressure. The injected fuel is in the form of mist and mixed with air for combustion.Therefore, diesel engines can use heavy fuel with poor volatility or low-quality fuel, such as crude oil and residual oil.
When burning crude oil and residual oil, in addition to filtering impurities and water, the oil supply system shall be preheated and insulated to reduce viscosity for transportation and injection.The diesel engine can also use light fuels such as ethanol, gasoline and methanol if a suitable combustion chamber is used.In order to improve the ignitability of light fuel, additives can be added to increase the cetane number, or mixed with diesel.Some gaseous fuels, such as natural gas, liquefied petroleum gas, biogas and producer gas, can also be used as the fuel of diesel engines, but at this time, gas fuels are usually used as the main fuel, and a small amount of diesel is used for ignition. This kind of engine is called dual fuel internal combustion engine.
biodiesel
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The products of China's biodiesel industry can be divided into energy products and fine chemical products, of which energy products refer to biodiesel fuel, and fine chemical products refer to the products obtained by deep processing with fatty acid methyl ester as raw material. The representative products include high carbon fatty acid methyl ester, epoxy epoxy fatty acid methyl ester, dimeric acid, erucic acid, oleic acid methyl ester and glycerol.
