Background
The coal tar is a liquid byproduct generated in the coal deep processing process, has pungent smell, and can be divided into low-temperature coal tar, medium-temperature coal tar and high-temperature coal tar according to different pyrolysis temperatures. Coal tar has a complex composition, contains a large amount of polycyclic aromatic hydrocarbon, S, N, O and other heteroatoms, metal and other non-hydrocarbon compounds, and is mainly processed and utilized by a hydrogenation process at present. Coal tar hydrogenation technology is the key technology for the most reasonable and effective coal tar processing. The coal tar hydro-upgrading process can be roughly divided into two parts: hydrofinishing and hydrocracking. The hydrofining part is mainly used for removing sulfur, nitrogen, oxygen, heavy metals and other impurity molecules in the coal tar, is a main reaction in the coal tar hydrogenation upgrading process, and determines whether the product meets the subsequent production requirements or not according to the quality of hydrofining. The purpose of hydrocracking is to produce reactions such as alkane cracking, naphthene cracking and arene cracking on coal tar under the action of high temperature and high pressure, catalyst and hydrogen, and to produce the hydrogenation process of light fuel oil. At present, medium-temperature coal tar is mainly used for producing chemicals such as aromatic hydrocarbon and the like by a method combining hydrofining and hydrocracking, so that the high-efficiency utilization of coal tar resources is realized.
In the prior art, there are two schemes for utilizing coal tar, scheme one: the method is characterized in that coal tar hydrogenation distillate is used as a raw material, light diesel oil is produced after hydrofining, and mixed aromatic hydrocarbon is produced after hydrocracking and reforming. The technical scheme mainly comprises the following steps: (1) The mixed aromatic hydrocarbon is produced by taking partial distillate oil as a raw material, the whole fraction of the coal tar is not fully utilized, and the comprehensive economy is low; (2) The product mixed aromatic hydrocarbon is not effectively separated and purified, and the added value of the product is required to be further improved. Scheme II: the method is characterized in that the whole fraction of medium-low temperature coal tar is used as a raw material, the light phase is cracked and refined after pretreatment fractionation, the heavy phase is cracked and refined and cracked again after twice cracking, and finally, the whole fraction coal tar is hydrogenated to prepare monocyclic aromatic hydrocarbons such as benzene, toluene, xylene and the like. The technical scheme mainly comprises the following steps: the medium-low temperature coal tar is only subjected to hydrofining and hydrocracking to produce benzene, toluene, xylene and other monocyclic aromatic hydrocarbon, the product structure is single, and the coal tar is not subjected to scientific chemical cutting, so that the products such as the high-yield aromatic hydrocarbon of the coal tar are realized.
For this reason, CN219689638U in the patent document shows a system for producing chemicals such as aromatic hydrocarbon from medium-temperature coal tar, and although various chemicals such as benzene, toluene, xylene can be obtained by the system, these chemicals have problems of not reaching the standard of quality and low yield.
Disclosure of Invention
Therefore, the invention aims to overcome the defects of substandard quality and low yield of the obtained chemicals in the prior art, thereby providing a method for preparing chemicals and special fuels from medium-temperature coal tar.
The invention provides a method for preparing chemicals and special fuels from medium-temperature coal tar, which comprises the following steps of;
(1) The method comprises the steps of taking medium-temperature coal tar as a raw material, separating after coking and decarburization treatment, and collecting a mixed fraction at 120-450 ℃;
(2) The mixed fraction in the step (1) is heated at 320-380 ℃ and the pressure is less than or equal to 15MPa and the airspeed is 0.3-0.6h-1 Hydrofining the mixture under the condition that the hydrogen-oil ratio is less than or equal to 800, separating to obtain light components and tail oil, and separating the tail oil at the temperature of 340-380 ℃ and the pressure of less than or equal to 15MPa and the airspeed of 0.6-1.0h-1 Hydrocracking under the condition that the hydrogen-oil ratio is less than or equal to 800, separating, and collecting heavy naphtha;
(3) Taking heavy naphtha and light components, wherein the temperature is 200-270 ℃, the pressure is less than or equal to 15MPa, and the airspeed is 0.7-1.1 h-1 Catalytic reforming is carried out under the condition that the hydrogen-oil ratio is less than or equal to 800, so as to obtain a reformate; dewaxing and separating the reformed product under the conditions of the temperature of 60-150 ℃ and the pressure of 0.1-1.5 MPa to obtain at least one of benzene, toluene, xylene and aromatic hydrocarbon with the boiling point higher than 140 ℃.
In the present invention, the term chemical is used for chemical raw materials in various industries, such as benzene, toluene, xylene, aromatic hydrocarbons having a boiling point higher than 140 ℃, and the like.
The special fuel is a fuel applied to special industries such as aerospace, military industry and the like, for example aviation kerosene and the like.
Further, after the separation in the step (3), benzene in a fraction of 75-85 ℃ is collected.
Further, after the separation in the step (3), toluene in a fraction of 105-115 ℃ is collected.
Further, after the separation in the step (3), the xylene in the fraction of 135-145 ℃ is collected.
Further, after the separation in the step (3), other aromatic hydrocarbons of >140 ℃ are collected.
Further, after separation in the step (2), collecting aviation kerosene in a fraction of 130-260 ℃; and/or collecting the white oil of the distillation section at 260-355 ℃.
Further, after separation in the step (2), 180-360 ℃ fraction diesel oil is collected.
Further, the coking and decarburization temperature is 420-460 ℃ and the coking and decarburization time is 24-48 h.
Further, the distillation range of the heavy naphtha is 70-180 ℃.
Further, the dewaxing device separates alkane from reformate to obtain mixed arene.
The technical scheme of the invention has the following advantages:
1. the method for preparing chemicals and special fuels from the medium-temperature coal tar comprises the following steps of (1) taking the medium-temperature coal tar as a raw material, separating after coking and decarburization treatment, and collecting mixed fractions at 120-450 ℃; (2) The mixed fraction in the step (1) is heated at 320-380 ℃ and the pressure is less than or equal to 15MPa and the airspeed is 0.3-0.6h-1 Hydrofining the mixture under the condition that the hydrogen-oil ratio is less than or equal to 800, separating to obtain light components and tail oil, and separating the tail oil at the temperature of 340-380 ℃ and the pressure of less than or equal to 15MPa and the airspeed of 0.6-1.0h-1 Hydrocracking under the condition that the hydrogen-oil ratio is less than or equal to 800, separating, and collecting heavy naphtha; (3) Taking heavy naphtha and light components, wherein the temperature is 200-270 ℃, the pressure is less than or equal to 15MPa, and the airspeed is 0.7-1.1 h-1 Catalytic reforming is carried out under the condition that the hydrogen-oil ratio is less than or equal to 800, so as to obtain a reformate; dewaxing and separating the reformed product under the conditions of the temperature of 60-150 ℃ and the pressure of 0.1-1.5 MPa to obtain at least one of benzene, toluene, xylene and aromatic hydrocarbon with the boiling point higher than 140 ℃. Collecting and hydrofining the mixed fraction with 120-450 ℃ distillation range after coking and decarburization, separating to obtain light components and tail oil, hydrocracking the tail oil to obtain heavy naphtha, reforming, dewaxing and separating the heavy naphtha and the light components, and combiningThe control of each process condition greatly improves the yield of chemicals such as benzene, toluene, dimethylbenzene, aromatic hydrocarbon with boiling point higher than 140 ℃ and the like, and improves the quality of each chemical.
2. According to the method for preparing chemicals and special fuels from the medium-temperature coal tar, the medium-temperature coal tar is subjected to coking and decarburization treatment and then separated to obtain mixed fractions, and the characteristic fuels such as aviation kerosene, white oil and diesel oil are also collected after separation in the step (2). The method can realize the customized production of aviation kerosene, white oil and high-cetane-number diesel oil products, and different amounts of aviation kerosene, white oil and high-cetane-number diesel oil can be produced according to different customer requirements and market demands.
3. The method for preparing chemicals and special fuels from the medium-temperature coal tar provided by the invention takes the medium-temperature coal tar as a raw material, and can also obtain medium-temperature coal tar pitch and phenol oil after separation after coking and decarbonization treatment, wherein the medium-temperature coal tar pitch can be used for further producing needle coke, and the phenol oil can be used for separating and purifying phenol products.
Detailed Description
The following examples are provided for a better understanding of the present invention and are not limited to the preferred embodiments described herein, but are not intended to limit the scope of the invention, any product which is the same or similar to the present invention, whether in light of the present teachings or in combination with other prior art features, falls within the scope of the present invention.
The specific experimental procedures or conditions are not noted in the examples and may be followed by the operations or conditions of conventional experimental procedures described in the literature in this field. The reagents or apparatus used were conventional reagent products commercially available without the manufacturer's knowledge. Wherein, the medium temperature coal tar meets the regulations of the local standard DB 61/T385-2006 of Shaanxi province.
The following examples of the present invention were all completed using a medium temperature coal tar chemical and specialty fuel system as provided in fig. 1.
As shown in fig. 1, a system for preparing chemicals and special fuel from medium-temperature coal tar comprises a coking tower 1, a first fractionating tower 2, a hydrofining device 3, a second fractionating tower 4, a hydrocracking device 5, a third fractionating tower 6, a reforming device 7, a dewaxing device 8 and a fourth fractionating tower 9 which are connected in sequence;
the coking tower 1 is used for removing carbon in medium-temperature coal tar serving as a raw material; the first fractionating tower 2 is used for separating fractions from the medium-temperature coal tar with carbon removed; the hydrofining device 3 is used for removing S, N heteroatoms contained in the mixed fraction to obtain a hydrofining product; a second fractionation column 4 for separating the hydrofinished product.
The top discharge end of the first fractionating tower 2 is used for discharging rich gas, the feed end is connected with the coking tower 1, the bottom discharge end is used for discharging medium-temperature asphalt, the bottom discharge end can be connected with a needle coke production device and used for preparing needle coke, the middle discharge end is connected with the hydrofining device 3, and the mixed fraction is conveyed to the hydrofining device 3;
the feeding end of the hydrocracking device 5 is respectively connected with the bottom discharging end of the second fractionating tower 4 and the bottom discharging end of the third fractionating tower 6, and is used for hydrocracking tail oil separated by the second fractionating tower 4 and heavy components separated by the third fractionating tower 6; the feeding end of the third fractionating tower 6 is connected with the discharging end of the hydrocracking device 5, and is used for separating cracked products. The third fractionating tower 6 is used for separating rich gas, light naphtha, heavy naphtha, aviation kerosene, white oil, diesel with high cetane number and heavy naphtha from the hydrocracking product. The heavy naphtha discharge end of the third fractionating tower 6 is connected with the feed end of the reformer 7.
The feeding end of the reforming device 7 is also connected with the top discharging end of the second fractionating tower 4, and is used for conveying the light components of the second fractionating tower 4 to the reforming device 7 for catalytic reforming, so as to obtain a catalytic reforming product of polyaromatics.
The feed end of the dewaxing device 8 is connected with the discharge end of the reforming device 7. The dewaxing device 8 is used for removing alkane, the discharge end of the dewaxing device 8 is connected with a fourth fractionating tower 9, and the fourth fractionating tower 9 is used for separating catalytic reforming products from which alkane components are removed so as to separate benzene, toluene, xylene and high-boiling aromatic hydrocarbon.
Example 1
The embodiment provides a method for preparing chemicals and special fuels from medium-temperature coal tar, which comprises the following steps:
(1) Sending the medium-temperature coal tar into a coking tower, carrying out coking decarburization treatment, sending the medium-temperature coal tar into a first fractionating tower for separation, and collecting a first distillation section (mixed fraction); the temperature and time of the coking and decarburization treatment, the distillation range of the mixed fraction, and the overhead temperature and pressure of the first fractionator are shown in table 1 below.
TABLE 1
(2) And (3) sending the mixed fraction into an existing conventional hydrofining device for hydrofining, wherein the hydrofining temperature, pressure, airspeed and hydrogen oil ratio are shown in the following table 2, sending the hydrofined product into a second fractionating tower for separation, obtaining light components at the top of the tower, and obtaining tail oil at the bottom of the tower. The tail oil was fed to an existing conventional hydrocracking unit for hydrocracking at the temperature, pressure, space velocity and hydrogen oil ratio shown in table 2 below. The hydrocracking product is sent to a third fractionating tower for separation. Rich gas is generated at the top of the third fractionating tower, heavy components generated at the bottom of the third fractionating tower flow back into the hydrocracking device, and heavy naphtha (distillation range: 70-180 ℃), aviation kerosene (distillation range: 130-260 ℃) and white oil (distillation range: 260-355 ℃) are collected in the tower.
TABLE 2
(3) The heavy naphtha and the light fraction obtained in the second fractionating column were fed to an existing conventional reforming apparatus for catalytic reforming at the temperature, pressure, space velocity and hydrogen-oil ratio shown in table 3 below. The reformed product is sent to a dewaxing device for dewaxing to obtain aromatic hydrocarbon, and the dewaxing temperature and pressure are shown in the following table 3. The aromatic hydrocarbon is sent to a fourth fractionating tower for separation, and benzene (distillation range: 75 ℃ to 85 ℃), toluene (distillation range: 105 ℃ to 115 ℃), xylene (distillation range: 135 ℃ to 145 ℃) and aromatic hydrocarbon with boiling point higher than 140 ℃ (distillation range: more than 140 ℃) are obtained.
TABLE 3 Table 3
Example 2
The embodiment provides a method for preparing chemicals and special fuels from medium-temperature coal tar, which comprises the following steps:
(1) Sending the medium-temperature coal tar into a coking tower, carrying out coking decarburization treatment, sending the medium-temperature coal tar into a first fractionating tower for separation, and collecting a first distillation section (mixed fraction); the temperature and time of the coking and decarburization treatment and the distillation ranges of the mixed fractions are shown in Table 4 below.
TABLE 4 Table 4
(2) And (3) sending the mixed fraction into an existing conventional hydrofining device for hydrofining, wherein the hydrofining temperature, pressure, airspeed and hydrogen oil ratio are shown in the following table 5, sending the hydrofined product into a second fractionating tower for separation, obtaining light components at the top of the tower, and obtaining tail oil at the bottom of the tower. The tail oil was sent to a hydrocracking unit for hydrocracking at the temperature, pressure, space velocity and hydrogen oil ratio shown in table 5 below. The hydrocracking product is sent to a third fractionating tower for separation. Rich gas is generated at the top of the third fractionating tower, heavy components generated at the bottom of the third fractionating tower flow back into the hydrocracking device, and heavy naphtha (distillation range: 70-180 ℃), aviation kerosene (distillation range: 130-260 ℃) and white oil (distillation range: 260-355 ℃) are collected in the tower. The extraction ratio of heavy naphtha and aviation kerosene can be adjusted according to market demands.
TABLE 5
(3) The heavy naphtha and the light fraction obtained in the second fractionating column were fed to a reformer for catalytic reforming at the temperature, pressure, space velocity and hydrogen-oil ratio shown in table 6 below. The reformed product is sent to a dewaxing device for dewaxing, aromatic hydrocarbon is obtained respectively, and the dewaxing temperature and pressure are shown in the following table 6. The aromatic hydrocarbon is sent to a fourth fractionating tower for separation to obtain at least one of benzene (distillation range: 75-85 ℃), toluene (distillation range: 105-115 ℃), xylene (distillation range: 135-145 ℃) and aromatic hydrocarbon with boiling point higher than 140 ℃ (distillation range: more than 140 ℃).
TABLE 6
Example 3
The embodiment provides a method for preparing chemicals and special fuels from medium-temperature coal tar, which comprises the following steps:
(1) Sending the medium-temperature coal tar into a coking tower, carrying out coking decarburization treatment, sending the medium-temperature coal tar into a first fractionating tower for separation, and collecting a first distillation section (mixed fraction); the temperature and time of the coking and decarburization treatment and the distillation ranges of the mixed fractions are shown in Table 7 below.
TABLE 7
(2) And (3) sending the mixed fraction into an existing conventional hydrofining device for hydrofining, wherein the hydrofining temperature, pressure, airspeed and hydrogen oil ratio are shown in the following table 8, sending the hydrofined product into a second fractionating tower for separation, obtaining light components at the top of the tower, and obtaining tail oil at the bottom of the tower. The tail oil was sent to a hydrocracking unit for hydrocracking at the temperature, pressure, space velocity and hydrogen oil ratio shown in table 8 below. The hydrocracking product is sent to a third fractionating tower for separation. Rich gas is generated at the top of the third fractionating tower, heavy components generated at the bottom of the third fractionating tower flow back into the hydrocracking device, and heavy naphtha (distillation range: 70-180 ℃) and diesel oil with high cetane number (distillation range: 180-360 ℃) are collected from the tower.
TABLE 8
(3) The heavy naphtha and the light fraction obtained in the second fractionating column were fed to a reformer for catalytic reforming at the temperature, pressure, space velocity and hydrogen-oil ratio shown in table 9 below. The reformed product is sent to a dewaxing device for dewaxing, aromatic hydrocarbon is obtained respectively, and the dewaxing temperature and pressure are shown in the following table 9. The aromatic hydrocarbon is sent to a fourth fractionating tower for separation to obtain at least one of benzene (distillation range: 75-85 ℃), toluene (distillation range: 105-115 ℃), xylene (distillation range: 135-145 ℃) and aromatic hydrocarbon with boiling point higher than 140 ℃ (distillation range: more than 140 ℃).
TABLE 9
Example 4
The embodiment provides a method for preparing chemicals and special fuels from medium-temperature coal tar, which comprises the following steps:
(1) Sending the medium-temperature coal tar into a coking tower, carrying out coking decarburization treatment, sending the medium-temperature coal tar into a first fractionating tower for separation, and collecting a first distillation section (mixed fraction); the temperature and time of the coking and decarburization treatment and the distillation ranges of the mixed fractions are shown in Table 10 below.
Table 10
(2) The mixed fraction is sent into the conventional hydrofining device for hydrofining, the hydrofining temperature, pressure, airspeed and hydrogen oil ratio are shown in the following table 11, the product after hydrofining is sent into a second fractionating tower for separation, the light component is obtained at the top of the tower, and the tail oil is obtained at the bottom of the tower. The tail oil was sent to a hydrocracking unit for hydrocracking at the temperature, pressure, space velocity and hydrogen oil ratio shown in table 11 below. The hydrocracking product is sent to a third fractionating tower for separation. Rich gas is generated at the top of the third fractionating tower, heavy components generated at the bottom of the third fractionating tower flow back into the hydrocracking device, and heavy naphtha (distillation range: 70-180 ℃) and diesel oil with high cetane number (distillation range: 180-360 ℃) are collected from the tower.
TABLE 11
(3) The heavy naphtha and the light fraction obtained in the second fractionating column were fed to a reformer for catalytic reforming at the temperature, pressure, space velocity and hydrogen-oil ratio shown in table 12 below. The reformed product is sent to a dewaxing device for dewaxing to obtain aromatic hydrocarbon, and the dewaxing temperature and pressure are shown in the following table 12. The aromatic hydrocarbon is sent to a fourth fractionating tower for separation to obtain at least one of benzene (distillation range: 75-85 ℃), toluene (distillation range: 105-115 ℃), xylene (distillation range: 135-145 ℃) and aromatic hydrocarbon with boiling point higher than 140 ℃ (distillation range: more than 140 ℃).
Table 12
Experimental example 1
The properties and yields of benzene (distillation range: 75 ℃ C. To 85 ℃ C.), toluene (distillation range: 105 ℃ C. To 115 ℃ C.), and xylene (distillation range: 135 ℃ C. To 145 ℃ C.) obtained in examples 1 to 4 were examined, and the results are shown in the following table.
TABLE 13 benzene Property composition and yield
TABLE 14 toluene Property composition and yield
TABLE 15 xylene Property composition and yield
Experimental example 2
The properties of the high boiling aromatic hydrocarbons (> 140 ℃) obtained in examples 1 and 2 were examined and the results are shown in the following table.
TABLE 16 physicochemical Properties of high boiling aromatic hydrocarbons (> 140 ℃ C.) as solvents
Yield of high boiling aromatic hydrocarbons obtained in examples 1 to 4: 5-10%.
Experimental example 3
The properties of the aviation kerosene (130 ℃ to 260 ℃) and white oil (260 ℃ to 355 ℃) products obtained in example 1 were tested, and the results are shown in the following table.
Table 17 aviation kerosene product Performance
Table 18 white oil product properties
Experimental example 4
The properties of the high cetane number diesel oil (180 ℃ to 360 ℃) obtained in example 3 were tested, and the results are shown in the following table.
Table 19 high cetane number diesel product Performance
It is apparent that the above examples are given by way of illustration only and are not limiting of the embodiments. Other variations or modifications of the above teachings will be apparent to those of ordinary skill in the art. It is not necessary here nor is it exhaustive of all embodiments. While still being apparent from variations or modifications that may be made by those skilled in the art are within the scope of the invention.