A method for blending light crude oil

Abstract

The present invention relates to a method for blending light crude oil, comprising: (1) analyzing a mixed crude oil after electric desalting in a normal and low pressure device to obtain a density and a real boiling point distillation curve, and analyzing a distillate obtained by processing the mixed crude oil in a normal and low pressure device to obtain a density and an Engler distillation curve; (2) referring to a desired light crude oil, comparing the distillate curve with the real boiling point distillation curve of the mixed crude oil, selecting the distillate obtained by processing the mixed crude oil, using a process simulation software to establish an oil product mixture, and using a controller to set constraint conditions to obtain the proportion of each component of the blended crude oil. The method of the present invention can obtain a blended crude oil with properties similar to those of the desired light crude oil by mixing the mixed crude oil and its distillate being processed in a normal and low pressure device in a proportion, and the light crude oil can meet the processing requirements. The method of the present invention is simple and fast, and does not require the establishment of a complex model to obtain a blended crude oil with properties similar to those of the light crude oil, and can be used in the field of direct cracking of light crude oil.

Description

Technical Field

[0001] The present invention relates to the crude oil blending aspect in the field of petrochemical industry, in particular to the blending aspect of light crude oil. Background Art

[0002] After processing, crude oil is mainly used to produce finished oil and chemical products. In actual industry, in order to obtain better benefits from steam cracking, fractions with high straight-chain alkane content are generally selected as cracking raw materials as much as possible. Therefore, the fractions of crude oil entering the ethylene unit after processing are not high. Generally, a 10 million ton refining unit and a million ton ethylene unit are required to be integrated for maximum benefits. In recent years, with the rapid development of new energy vehicles such as electric vehicles and the rapid decline in automobile fuel economy, the growth of demand for finished oil has slowed down, while the demand for chemical products has maintained a high growth rate and has become the main driving force for the growth of crude oil demand.

[0003] The route of directly producing chemical products from crude oil can effectively solve the above problems. Major domestic and foreign companies have developed crude oil steam cracking to produce olefins technology. So far, ExxonMobil and Saudi Aramco have reported industrialization progress. ExxonMobil has built and put into production a plant in Singapore, successfully realizing the industrialization of crude oil cracking to produce olefins technology. Saudi Aramco has also announced that it will build a comprehensive plant for direct production of chemicals from crude oil, and at the same time develop technology for hot crude oil to produce chemicals. The crude oil steam cracking to produce olefins technology of companies such as LyondellBasell, Shell and Lummus is still in the research and development stage.

[0004] The above-mentioned crude oils that can be used for direct cracking are all light crude oils.

[0005] The international oil market classifies crude oil by density and sulfur content and calculates the price of different crude oils. Generally, light crude oil refers to crude oil with a density of less than 0.852 g / cm at 20°C. 3 Medium crude oil refers to crude oil with a density of 0.852 g / cm at 20°C. 3 ~0.930g / cm 3 , API° classification standard is also often used. API° is also called specific gravity index. Light crude oil has API° greater than 34, and medium crude oil has API° between 20 and 34. The definition of API° is shown in the following formula.

[0006]

[0007] in, It is the relative density of oil, which refers to the ratio of the density of oil to that of water at 15.6°C.

[0008] Crude oil has a complex composition and many components, and its detailed chemical composition is usually impossible to obtain. Therefore, laboratory crude oil evaluation curves are usually used to characterize crude oil rather than actual composition. Crude oil evaluation curves mainly refer to real boiling point distillation curves. Real boiling point distillation can best represent the relationship between the true composition of oil products and temperature. It is a distillation measurement carried out in an efficient distillation column with a large reflux ratio. Although the number of plates used in the distillation column in different laboratories is different, the separation of oil products in real boiling point distillation is in the order of volatility of the fractions. The normal boiling point of the heaviest component that can be separated during the distillation process is about 520°C. Plotting the distillation temperature against the weight or volume percentage of the distillate is the real boiling point distillation curve.

[0009] Light crude oil generally has a lower sulfur content, and low-sulfur light oil is 200-300 yuan / ton more expensive than medium or heavy crude oil in crude oil prices. The technology of direct cracking of light crude oil to produce olefins uses light crude oil to enter the convection section of the cracking furnace after desalting and dehydration, and enter the flash tank after heat exchange. The light components are separated and enter the radiation section of the cracking furnace for cracking, and the heavy components are returned to the refinery for processing. The purchase price of light crude oil is high, and it needs to be desalted and dehydrated when directly cracked. The existing atmospheric and vacuum devices generally process light crude oil and a mixture of medium and heavy medium crude oil. If the existing devices are used to carry out research on the direct cracking of light crude oil to produce olefins, it is necessary to stop processing the mixed crude oil, which will also affect the subsequent secondary processing devices. Summary of the invention

[0010] The object of the present invention is to provide a method for blending light crude oil, which utilizes the mixed crude oil and the distillate oil obtained after processing by the regular decompression device, refers to the required light crude oil, calculates the proportion of each component through process simulation software, and obtains the light crude oil after blending.

[0011] The technical solution of the present invention is as follows:

[0012] A method for preparing light crude oil comprises the following steps:

[0013] (1) The mixed crude oil after electrical desalting in the atmospheric and vacuum unit is analyzed to obtain a density and a true boiling point distillation curve, and the distillate oil obtained by processing the mixed crude oil in the atmospheric and vacuum unit is analyzed to obtain a density and an Engler distillation curve.

[0014] (2) Referring to the required light crude oil, the actual boiling point distillation curve of the mixed crude oil is compared with that of the mixed crude oil, and the distillate oil obtained by processing the mixed crude oil is selected. The oil product mixture is established by using process simulation software, and the constraint conditions are set by using a controller to obtain the proportion of each component of the blended crude oil.

[0015] The distillate oil may be one or more of naphtha, kerosene, diesel and wax oil obtained by processing mixed crude oil through a regular decompression unit.

[0016] The constraint conditions are that the difference between the gravity index of the blended crude oil and the required light crude oil is ±0.50, and the difference between the 10% to 70% distillation temperature in the actual boiling point distillation curve of the blended crude oil and the required light crude oil distillation temperature is ≮20°C.

[0017] In the step (1), the mixed crude oil after electrical desalting in the atmospheric and vacuum device is analyzed by near infrared spectroscopy.

[0018] The process simulation software is preferably ProⅡ9.0 or above version.

[0019] The method of the present invention can obtain a blended crude oil with similar properties to the required light crude oil by mixing the mixed crude oil and its distillate being processed in atmospheric and vacuum conditions in a proportion, and the light crude oil can meet the processing needs. The method of the present invention is simple and fast, and does not require the establishment of a complex model, and can obtain a blended crude oil with similar properties to the light crude oil, which can be used in the field of direct cracking of light crude oil.

[0020] The present invention aims to utilize the mixed medium crude oil processed by the current atmospheric and vacuum devices, and the distillate oil obtained after the atmospheric and vacuum devices are processed, including one or more of naphtha, kerosene, diesel and wax oil. The process simulation software is used to establish the oil product mixture, and the controller is used to refer to the density and actual boiling point distillation curve of the required light crude oil to obtain the proportion of each component. Then, the light oil product blended according to the proportion is used for the industrial test of the direct cracking of light crude oil to produce olefins. There is no need to stop the atmospheric and vacuum devices for desalting and dehydrating the light crude oil and reducing the processing load of the subsequent secondary devices, which can minimize the impact on the existing process flow and save the purchase cost of light crude oil. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 : Actual boiling point distillation curve of mixed crude oil and Cushing crude oil in Example 1;

[0022] Figure 2 : Scheme 1 in Example 1 and the actual boiling point curve of Cushing crude oil;

[0023] Figure 3 : The actual boiling point curve of Scheme 2 and Cushing crude oil in Example 1;

[0024] Figure 4 : Schematic diagram of simulation calculation of crude oil blending ratio in scheme 1 of embodiment 1;

[0025] Figure 5 : Schematic diagram of the simulation calculation of the crude oil blending ratio in Scheme 2 of Example 1.

[0026] CRUDEOIL crude oil, FLASH flash tank (simulated electric desalting), NAPHTH naphtha, KEROSENE kerosene, DIESEL diesel, WAXOIL wax oil, SPLITTER1-5 desalted crude oil, naphtha, kerosene, diesel, wax oil splitter, MIXER blended crude oil mixer, BLEND blended crude oil, OPTIMIZER controller. S1 desalted crude oil enters splitter, S2 desalted crude oil enters atmospheric pressure tower, S3 desalted crude oil enters blended crude oil mixer, S4 naphtha exits atmospheric pressure reduction unit, S5 naphtha enters blended crude oil mixer, S6 kerosene exits atmospheric pressure reduction unit, S7 kerosene enters blended crude oil mixer, S8 diesel exits atmospheric pressure reduction unit, S9 diesel enters blended crude oil mixer, S10 wax oil exits atmospheric pressure reduction unit, S11 wax oil enters blended crude oil mixer. DETAILED DESCRIPTION

[0027] The method of the present invention first analyzes the mixed crude oil after electric desalting in the atmospheric and vacuum device to obtain the density and the actual boiling point distillation curve, and analyzes the distillate oil obtained by processing the mixed crude oil in the atmospheric and vacuum device to obtain the density and the Engler distillation curve. With reference to the required light crude oil, the actual boiling point distillation curve of the mixed crude oil is compared, the distillate oil obtained by processing the mixed crude oil is selected, the process simulation software is used to establish the oil product mixing, and the controller is used to set the constraint conditions to obtain the proportion of each component of the blended crude oil.

[0028] The method of the present invention can obtain light crude oil with similar properties to the required light crude oil by mixing the mixed crude oil and its fraction oil being processed in atmospheric and vacuum decompression, and the light crude oil can meet the processing needs.

[0029] The method of the invention is simple and rapid, and does not require the establishment of a complex model, and can obtain a blended crude oil with properties similar to the light crude oil, and can be used in fields such as direct cracking of light crude oil.

[0030] The present invention is described in detail below by way of examples, but the present invention is not limited thereto.

[0031] The near infrared spectra and measurement conditions used to measure the samples in the experiment are as follows:

[0032] Near infrared spectrometer: AntarisⅡ (Thermo Fisher), equipped with temperature control module. After the mixed crude oil sample is filled to about two-thirds of the 0.5 mm quartz cuvette, the opening is covered with a sealing film and placed in a temperature-controlled sample cell rack for transmission spectrum collection. The spectrum collection temperature is 38°C and the collection range is 3500-10000 cm -1 , repeated scanning 128 times, with a resolution of 8cm -1According to the crude oil quick evaluation method established in Chinese patent CN105388123 A, the crude oil density and true boiling point yield are obtained by using the near infrared spectrum.

[0033] In the experiment, the density of the distillate oil was determined according to GB / T 1884, the distillation range was determined according to GB / T 6536, and the vacuum distillation range was determined according to GB / T 9168.

[0034] The light crude oil required in the following Examples 1 and 2 is Cushing crude oil from the United States, and its crude oil density and true boiling point yield are shown in Table 1. It is required that the API° of the blended crude oil is 40.76±0.50, and the difference between the 10% to 70% distillation temperature in the true boiling point distillation curve and the Cushing crude oil distillation temperature is ≮20°C.

[0035] Table 1 Density and true boiling point yield of Cushing crude oil

[0036]

[0037] Example 1

[0038] The mixed crude oil processed by the atmospheric and vacuum unit is Basra Central: Oman: Darien = 45:45:10. The crude oil, naphtha, kerosene and wax oil after electrical desalting are taken. The density and actual boiling point yield of the crude oil after electrical desalting are obtained by near infrared quick evaluation. The actual boiling point distillation curve of the mixed crude oil is compared with that of Cushing crude oil. Figure 1 .

[0039] Depend on Figure 1It can be seen that the mixed crude oil is heavier than Cushing crude oil, and the temperature at each distillation volume is higher than that of Cushing crude oil. The density and distillation range of naphtha, kerosene, diesel and wax oil are obtained using standard methods, and the results are shown in Table 2. As can be seen from Table 2, the boiling point ranges of the four components of naphtha, kerosene, diesel and wax oil just overlap. With these four distillate oils and the mixed crude oil after electrical desalting, the oil blending module in ProⅡ is used to establish four groups of materials, input the properties of the four groups of materials, generate a controller, and limit the flow rate of the four groups of materials involved in the blending (0.60-0.80 for desalted crude oil, 0.05-0.25 for naphtha, 0.05-0.20 for kerosene, and 0 for wax oil). .03-0.20, diesel 0.03-0.20), with API° as the limiting means, when API° is 40.76, the controller is used to calculate and obtain the blending crude oil ratio, scheme one is stripped crude oil: naphtha: kerosene: wax oil = 0.67: 0.21: 0.09: 0.03, scheme two is stripped crude oil: naphtha: kerosene: diesel = 0.69: 0.22: 0.84: 0.05, the results are shown in Table 3. From the data in Table 3, it can be seen that the difference between the actual boiling point 10%, 30%, 50% and 70% distillation volume temperature of the blending crude oil scheme one and the distillation temperature of Cushing crude oil is less than 20°C, and among the differences between the actual boiling point 10%, 30%, 50% and 70% distillation volume temperature of the blending crude oil scheme two and the distillation temperature of Cushing crude oil, 50% of the difference is 24.19°C, which does not meet the requirement that the temperature difference is less than 20°C, and the rest are less than 20°C.

[0040] Comparison of the simulation calculation of blending oil scheme 1 and scheme 2 and the actual boiling point distillation curve of Cushing crude oil is shown in Figure 2 and Figure 3 Compared with the overlap between the actual boiling point distillation curve of the blended crude oil and the actual boiling point distillation curve of Cushing crude oil, Scheme 1 is better than Scheme 2. Scheme 2 has a significant deviation at 40% to 60% distillation temperature.

[0041] Blending oil solution 1 Figure 4 and Figure 5 This is a schematic diagram of the simulation calculation of the blending crude oil ratio for Scheme 1 and Scheme 2 established using ProⅡ. Figure 4 In the process, the mixed crude oil processed by the atmospheric vacuum device is subjected to electrical desalting, and the naphtha, kerosene and wax oil obtained by the atmospheric vacuum device of the mixed crude oil are separated by a splitter and then mixed in a mixer to obtain the blended crude oil. The mixing ratio is calculated by a controller. Figure 5 In the process, the mixed crude oil processed by the atmospheric vacuum unit is subjected to electrical desalting, and the naphtha, kerosene and diesel oil processed by the atmospheric vacuum unit of the mixed crude oil are separated by a splitter and then mixed in a mixer to obtain the blended crude oil. The mixing ratio is calculated by a controller.

[0042] CRUDEOIL crude oil, FLASH flash tank (simulated electric desalting), NAPHTH naphtha, KEROSENE kerosene, DIESEL diesel, WAXOIL wax oil, SPLITTER1-5 desalted crude oil, naphtha, kerosene, diesel, wax oil splitter, MIXER blended crude oil mixer, BLEND blended crude oil, OPTIMIZER controller. S1 desalted crude oil enters splitter, S2 desalted crude oil enters atmospheric pressure tower, S3 desalted crude oil enters blended crude oil mixer, S4 naphtha exits atmospheric pressure reduction unit, S5 naphtha enters blended crude oil mixer, S6 kerosene exits atmospheric pressure reduction unit, S7 kerosene enters blended crude oil mixer, S8 diesel exits atmospheric pressure reduction unit, S9 diesel enters blended crude oil mixer, S10 wax oil exits atmospheric pressure reduction unit, S11 wax oil enters blended crude oil mixer.

[0043] Table 2 Properties of crude oil after degassing and distillate oil for blending

[0044]

[0045]

[0046]

[0047] Table 3 Blending oil and properties of different schemes

[0048]

[0049] Finally, the proportion determined by the blending crude oil plan 1 is selected for blending.

[0050] The technical solutions disclosed and proposed by the present invention can be realized by those skilled in the art by referring to the contents of this article and appropriately changing the conditions, routes and other links. Although the methods and preparation techniques of the present invention have been described through preferred embodiments, relevant technicians can obviously modify or re-combine the methods and technical routes described herein without departing from the content, spirit and scope of the present invention to realize the final preparation technology. It should be particularly noted that all similar substitutions and modifications are obvious to those skilled in the art, and they are all considered to be included in the spirit, scope and content of the present invention.

Claims

1. A method for preparing light crude oil, characterized in that: The steps include: (1) analyzing the mixed crude oil after electric desalting in the atmospheric and vacuum unit to obtain a density and a true boiling point distillation curve, and analyzing the distillate oil obtained by processing the mixed crude oil in the atmospheric and vacuum unit to obtain a density and an Engler distillation curve; (2) referring to the required light crude oil, comparing it with the actual boiling point distillation curve of the mixed crude oil, selecting the one obtained by processing the mixed crude oil, using process simulation software to establish oil product mixing, using a controller to set constraints, and obtaining the proportion of each component of the blended crude oil; The distillate oil is one or more of naphtha, kerosene, diesel or wax oil obtained by processing mixed crude oil through a regular vacuum unit; The constraint conditions are that the difference between the gravity index of the blended crude oil and the required light crude oil is ±0.50, and the difference between the 10% to 70% distillation temperature in the actual boiling point distillation curve of the blended crude oil and the required light crude oil distillation temperature is ≮20°C; Step 1) The mixed crude oil after electrical desalting in the atmospheric and vacuum unit is analyzed by near infrared spectroscopy.

2. The method according to claim 1, characterized in that The process simulation software is ProⅡ9.0 or above version.

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