Detailed Description
Specific embodiments of the present disclosure are described in detail below with reference to the accompanying drawings. It should be understood that the detailed description and specific examples, while indicating and illustrating the disclosure, are not intended to limit the disclosure.
In this disclosure, unless otherwise indicated, terms of orientation such as "upper and lower" are used to generally refer to the upper and lower of the device in normal use, e.g., with reference to the orientation of the drawing of fig. 1, and "inner and outer" are used with respect to the outline of the device. Furthermore, the terms "first, second, and third" are used for descriptive purposes only and are not to be interpreted as indicating or implying a relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defining "a first, second, and third" may explicitly or implicitly include one or more such feature. In the description of the present disclosure, the meaning of "a plurality" is two or more, unless explicitly defined otherwise.
The invention provides a combined processing method for producing more benzene, which comprises the steps of enabling raw oil to enter a pre-hydrogenation device 1 to conduct pre-hydrogenation reaction to obtain a pre-hydrogenation reaction product, enabling at least part of the pre-hydrogenation reaction product to conduct first separation to obtain C6-7 naphtha and C7+ naphtha, enabling the C6-7 naphtha to enter an alkane aromatization device 3 to conduct aromatization reaction to obtain aromatized hydrogen and first benzene-rich aromatic hydrocarbon, enabling the C7+ naphtha to enter a reforming device 4 to conduct reforming treatment to obtain reformed hydrogen and reformate, enabling the reformate to conduct second separation to obtain C6-7 naphtha, C8 aromatic hydrocarbon, C9+ aromatic hydrocarbon and heavy aromatic hydrocarbon, enabling the C9+ aromatic hydrocarbon to enter an aromatic hydrocarbon dealkylation device 6 to conduct dealkylation to obtain second benzene-rich aromatic hydrocarbon, enabling the first benzene-rich aromatic hydrocarbon, the reformed C6-7 naphtha and the second benzene-rich aromatic hydrocarbon to enter an aromatic hydrocarbon extraction device 7 to conduct aromatic hydrocarbon extraction to obtain non-aromatic hydrocarbon, benzene-rich product and toluene component, enabling the non-aromatic hydrocarbon-extracted hydrocarbon to enter the reforming device 4 to conduct reforming treatment to obtain reformed hydrogen and reformate, enabling the reformed oil to conduct second separation to obtain reformed hydrogen and enabling the reformed hydrocarbon to enter the first hydrogen to enter the first part of the reforming device 1 to be at least partially subjected to hydrogen removal and the hydrogen to be returned to the first reforming device 1.
According to the technical scheme, the method disclosed by the invention is used for carrying out pre-hydrogenation and separation on raw oil to obtain the C6-7 naphtha component and the C7+ naphtha component, wherein the C6-7 naphtha component and the non-aromatic raffinate oil are converted into benzene through alkane aromatization, the C7+ naphtha component is subjected to reforming treatment and separation, and the obtained C9+ aromatic hydrocarbon is converted into benzene through aromatic hydrocarbon dealkylation, so that the raw material source for producing benzene can be enlarged, the raw material cost for producing benzene is reduced, and the economic benefit is improved. In addition, the hydrogen used in the pre-hydrogenation reaction and the dealkylation treatment in the present disclosure comes from the reformer 4, so that the hydrogen consumption can be saved, and the cost of raw materials can be further reduced.
In one embodiment, the feedstock used in the present disclosure may be selected from oils with initial boiling point of 60-70 ℃ and final boiling point of 170-180 ℃, preferably one or more of straight run heavy naphtha, steam cracked raffinate, catalytic cracked raffinate and hydrogenated naphtha, i.e. the feedstock preferably has a boiling range (ASTM D-86) of 65-175 ℃. In this embodiment, ASTM D-86 refers to the American society for testing and materials published test method for D86 number, the standard test method for distillation of petroleum products at atmospheric pressure.
The method of pre-hydrogenation reaction carried out in the present disclosure is a conventional method in the art, and the present application does not require any special requirement, for example, in one embodiment of the present disclosure, the reaction conditions of the pre-hydrogenation reaction include a reaction temperature of 280 to 340 ℃, preferably 280 to 320 ℃, a reaction pressure of 2.4 to 3.8MPa, preferably 2.4 to 2.8MPa, a hydrogen partial pressure of 2.16 to 3.42MPa, preferably 2.16 to 2.52MPa, and a volume ratio of the pre-hydrogenation feed hydrogen to the raw oil of (90 to 100): 1, preferably 90:1.
The catalyst used in the pre-hydrogenation reaction of the present disclosure is a conventional choice in the art, and the present application does not require any special requirement, for example, in one embodiment of the present disclosure, the catalyst used in the pre-hydrogenation reaction includes an RS-1 catalyst or an S-125 catalyst, and is preferably an RS-1 catalyst.
In the above embodiment, the reaction conditions and the catalyst are used to convert the inexpensive raw oil into the purified naphtha, and the reactivity of the pre-hydrogenation reaction can be enhanced.
In one embodiment, the first separation is performed in a naphtha first separation unit, which is a conventional choice in the art, e.g., the first separation unit may be a naphtha fractionation unit, and further, the naphtha fractionation unit may be a C7 removal column.
In this embodiment, the pre-hydrogenation reaction product can be separated into C6-7 naphtha usable for the alkane aromatization reaction and C7+ naphtha usable for the reforming treatment by the first separation, and it should be noted that the content of C8+ component in the C6-7 naphtha is required to be below 0.1wt% according to the feed scale requirements of the subsequent alkane aromatization reaction and reforming treatment. In addition, the C7 component can exist in C6-7 naphtha or C7+ naphtha, the weight ratio of the C7 component in the C6-7 naphtha to the C6-7 naphtha and the weight ratio of the C7 component in the C7+ naphtha to the C7+ naphtha are not fixed, and the weight ratio is determined according to specific aromatization and reforming scales.
In one embodiment, the mixed aromatization feed obtained by mixing non-aromatic raffinate oil and the C6-7 naphtha is introduced into an aromatic dealkylation device 6 to contact with a catalyst, and aromatization reaction is carried out under the aromatization reaction condition, wherein the aromatization reaction condition comprises the reaction temperature of 450-530 ℃, preferably 450-500 ℃, the reaction pressure of 0.3-1.0MPa, preferably 0.3-0.5MPa, and the reaction mass space velocity of 1.0-1.5 h-1, preferably 1.2-1.5h-1.
The catalyst used in the aromatization reaction according to the present disclosure is a conventional choice in the art, and the present application is not particularly limited, for example, in a specific embodiment of the present disclosure, the catalyst used in the aromatization reaction is a PL-90 catalyst.
In the above embodiment, the mixed aromatization feed for the aromatization reaction may be paraffin and/or naphthene, preferably paraffin, wherein the impurity content of the mixed aromatization feed is required to include sulfur content of 0.1ppm or less, moisture content of 1ppm or less, nitrogen content of 0.5ppm or less, lead content of 1ppb or less, copper content of 1ppb or less, and arsenic content of 1ppb or less.
In order to make the treatment effect of the system match with the property of the raw oil, all the pre-hydrogenation reaction products generated by the pre-hydrogenation reaction can enter the first separation device 2, or part of the pre-hydrogenation reaction products can enter the first separation device 2, and the weight of the part of the pre-hydrogenation reaction products subjected to the first separation and the weight of the pre-hydrogenation reaction products are not required to be fixed, so that the pre-hydrogenation reaction products are determined according to specific aromatization and reforming scales. In addition, if the raw material for hydrogenation is a raw material oil of good quality, all the hydrogenation reaction products may be fed to the reformer 4 for subsequent treatment.
In a preferred embodiment, a portion of the pre-hydrogenation reaction product is mixed with the C7+ naphtha prior to reforming treatment, and the weight ratio of a portion of the pre-hydrogenation reaction product to the C7+ naphtha is not fixed as required, as determined by the particular aromatization and reforming scales.
In the above embodiment, the reforming device 4 and the reforming treatment are both selected conventionally in the art, and the conditions of the reforming treatment are not particularly limited, and include, for example, a pressure of 0.35MPa, an inlet temperature of 526-538 ℃, preferably 526-532 ℃, and a reforming space velocity of 1.2-2.25h-1, preferably 1.5-2.0h-1.
In one embodiment, the second separation is performed in a second separation unit 5, wherein the reformate separation unit comprises a C7 column, a xylene column, and a heavy aromatics column. In this embodiment, the reformate can be separated into reformed C6-7 naphtha and reformed aromatics by a second separation, wherein the reformed aromatics include C8 aromatics, C9+ aromatics, and heavy aromatics.
In this embodiment, the C7 removal column is capable of separating the reformed C6-7 naphtha and C8+ components from the reformate, wherein the separation requirement of the C7 removal column is that the content of C8+ components in the reformed C6-7 naphtha be less than 0.1 wt.%. In addition, the heavy aromatics column separation requirement is that the reformed C9+ aromatic component have less than 2 weight percent C10+ component.
In one embodiment, the dealkylation conditions include a temperature of 420-540 ℃, preferably 420-450 ℃, a pressure of 3.6-6.2MPa, preferably 3.6-4.0MPa, a hydrogen partial pressure of 2.52-5.58MPa, preferably 2.52-3.0MPa, and a hydrogen oil volume ratio of (3.0-4.0): 1, preferably (3.0-3.5): 1.
In one embodiment, the toluene component is mixed with the alien toluene component prior to its return to the aromatic dealkylation apparatus 6, wherein the weight ratio of alien toluene component to toluene component is not a fixed requirement, as determined by the dealkylation apparatus scale.
In one embodiment, the conditions for the aromatic hydrocarbon extraction treatment include a temperature of 89-175 ℃, preferably 121-168 ℃, a pressure of 0.08-0.1MPa, preferably 0.08MPa, and a stripping medium of sulfolane solvent.
In one embodiment, the reformed hydrogen further comprises a third reformed hydrogen, which is sent to other hydrogen utilization devices, and the method further comprises mixing the second partially reformed hydrogen with outsourced hydrogen and then entering the aromatic dealkylation device 6.
In this embodiment, the reformed hydrogen is preferably used for the first part reformed hydrogen and the second part reformed hydrogen, and the amounts of the first part reformed hydrogen and the second part reformed hydrogen are respectively supplied to the pre-hydrogenation device and the aromatic hydrocarbon dealkylation device, so that the amounts of the first part reformed hydrogen and the second part reformed hydrogen are determined according to the scale of the specific device, the application does not have special requirements, and only needs to meet the hydrogen requirements of the pre-hydrogenation reaction and the dealkylation treatment. The third partial reformed hydrogen is related to the amounts of the first partial reformed hydrogen and the second partial reformed hydrogen, and if the feeding scale is large, the consumption of the first partial reformed hydrogen and the second partial reformed hydrogen is large, the amount of the third partial reformed hydrogen, that is, the residual reformed hydrogen is small, and even the situation that no residual third partial reformed hydrogen exists, in which case outsource hydrogen needs to be added.
In one embodiment, as shown in FIG. 1, a method for combined process benzene production comprises:
S1, feeding raw oil 104 consisting of straight-run heavy naphtha 100, steam cracking raffinate 101, catalytic cracking raffinate 102 and other hydrogenated naphtha into a pre-hydrogenation device 1 for pre-hydrogenation reaction to obtain a pre-hydrogenation reaction product 105, wherein the pre-hydrogenation reaction condition comprises that the reaction temperature is 280-340 ℃, the reaction pressure is 2.8-3.8MPa, the hydrogen partial pressure is 2.16-3.42MPa, and the volume ratio of the raw oil 104 of the first partially reformed hydrogen 201 is (90-100): 1.
S2, enabling a part of the pre-hydrogenation reaction product 105 to enter a naphtha first separation device 2 for first separation to obtain C6-7 naphtha 106 and C7+ naphtha 111, wherein the separation requirement of the first separation is that the content of C8+ components in the C6-7 naphtha 106 is below 0.1 wt%.
S3, mixing the C6-7 naphtha 106 and the non-aromatic raffinate oil 116 to obtain a mixed aromatization feed 107, and feeding the mixed aromatization feed 107 into an alkane aromatization device 3 to perform alkane aromatization reaction to obtain first benzene-rich aromatic hydrocarbon 108 and aromatization hydrogen 203, wherein the reaction temperature of the alkane aromatization reaction is 450-530 ℃, the reaction pressure is 0.3-1.0MPa, and the reaction mass airspeed is 1.0-1.5 h-1. The impurity content of the mixed aromatization feed 107 comprises: S <0.1ppm, H2 O <1ppm, N <0.5ppm, pb <1ppb, cu <1ppb, as <1ppb.
S4, mixing the C7+ naphtha 111 and the rest of the pre-hydrogenation reaction product 110, and then entering a reforming device 4 for reforming treatment to obtain reformate 112 and reformed hydrogen, wherein the reaction pressure of the reforming treatment is 0.35MPa, and the inlet temperature of a reactor is 526-538 ℃. A first portion of reformed hydrogen 201 is fed to the pre-hydrogenation unit 1, a second portion of reformed hydrogen 202 and outsourced hydrogen 207 are fed to the aromatic dealkylation unit 6, and a third portion of reformed hydrogen 206 is fed to other hydrogen utilization units.
S5, enabling the reformate 112 to enter a second separation device 5 to obtain reformed C6-7 naphtha 113, C8 aromatic hydrocarbon 204, C9+ aromatic hydrocarbon 114 and heavy aromatic hydrocarbon 205. The separation requirements of the second separation device 5 comprise that the content of C8+ components in the reformed C6-7 naphtha 113 is less than 0.1 weight percent, and the content of C10+ components in the C9+ aromatic hydrocarbon 114 components is less than 2 weight percent.
S6, enabling the C9+ aromatic hydrocarbon 114 and the external C9+ components to enter an aromatic hydrocarbon dealkylation device 6 for dealkylation treatment to obtain second benzene-rich aromatic hydrocarbon 115. The dealkylation treatment condition comprises that the temperature is 420-540 ℃, the pressure is 3.6-6.2MPa, the hydrogen partial pressure is 2.52-5.58MPa, and the hydrogen-oil volume ratio is (3.0-4.0): 1.
S7, enabling the reformed C6-7 naphtha 113, the first benzene-rich aromatic hydrocarbon 108 and the second benzene-rich aromatic hydrocarbon 115 to enter an aromatic hydrocarbon extraction device 7 for aromatic hydrocarbon extraction treatment to obtain non-aromatic hydrocarbon raffinate oil 116, a benzene-rich product 117 and a toluene component 118, and returning the toluene component 118 to the aromatic hydrocarbon dealkylation device 6 after mixing with an external toluene component 119.
The method of the present invention is further illustrated by the following specific examples, which are not intended to limit the invention.
Example 1
As shown in fig. 3, the method for producing benzene in the combined process comprises the following steps:
S1, feeding raw oil 104 consisting of straight-run heavy naphtha 100, catalytic cracking raffinate 102 and other hydrogenated naphtha 103 into a pre-hydrogenation device 1 to perform a pre-hydrogenation reaction with first part of reformed hydrogen to obtain a pre-hydrogenation reaction product 105, wherein the pre-hydrogenation reaction condition comprises that the reaction temperature is 320 ℃, the reaction pressure is 2.8MPa, the hydrogen partial pressure is 2.52MPa, and the volume ratio of the first part of reformed hydrogen to the raw oil 104 is 90:1.
S2, feeding all (100 weight percent) of the prehydrogenation reaction products 105 into a first separation device 2 for first separation to obtain C6-7 naphtha 106 and C7+ naphtha 111, wherein the separation requirement of the first separation is that the content of C8+ components in the C6-7 naphtha 106 is below 0.1 weight percent.
S3, mixing the C6-7 naphtha 106 and the non-aromatic raffinate oil 116 to obtain a mixed aromatization feed 107, and feeding the mixed aromatization feed 107 into an alkane aromatization device 3 to perform alkane aromatization reaction to obtain first benzene-rich aromatic hydrocarbon 108 and aromatization hydrogen 203, wherein the reaction temperature of the alkane aromatization reaction is 450 ℃, the reaction pressure is 0.3MPa, and the reaction space velocity is 1.5h-1. The impurity content of the mixed aromatization feed 107 comprises: S <0.1ppm, H2 O <1ppm, N <0.5ppm, pb <1ppb, cu <1ppb, as <1ppb.
S4, enabling the C7+ naphtha 111 to enter a reforming device 4 for reforming treatment to obtain reformate 112 and reformed hydrogen, wherein the reaction pressure of the reforming treatment is 0.35MPa, and the inlet temperature of a reactor is 536 ℃. The first partially reformed hydrogen 201 was fed (3.7 wt.%) to the pre-hydrogenation unit 1, the second partially reformed hydrogen 202 was fed (52.2 wt.%) to the aromatic dealkylation unit 6, and the third partially reformed hydrogen 206 was fed (44.1 wt.%) to the other hydrogen-consuming units.
S5, enabling the components of the reformate 112 to enter a second separation device 5 to obtain reformed C6-7 naphtha 113, C8 aromatic hydrocarbon 204, C9+ aromatic hydrocarbon 114 and heavy aromatic hydrocarbon 205, wherein the C8 aromatic hydrocarbon 204 and the heavy aromatic hydrocarbon 205 are taken as products for take-out, and the separation requirement of the second separation device 5 comprises that the content of the C8+ component in the reformed C6-7 naphtha 113 is below 0.1 wt% and the content of the C10+ component in the C9+ aromatic hydrocarbon 114 is below 2 wt%.
S6, enabling the C9+ aromatic hydrocarbon 114 to enter an aromatic hydrocarbon dealkylation device 6 for dealkylation treatment to obtain second benzene-rich aromatic hydrocarbon 115. The dealkylation conditions included a temperature of 420 ℃, a pressure of 3.6MPa, a hydrogen partial pressure of 2.52MPa, and a hydrogen-oil volume ratio of 3.0:1.
S7, mixing reformed C6-7 naphtha 113, first benzene-rich aromatic hydrocarbon 108 and second benzene-rich aromatic hydrocarbon 115 to obtain mixed aromatic hydrocarbon-rich 109, and feeding the mixed aromatic hydrocarbon-rich 109 into an aromatic hydrocarbon extraction device 7 to perform aromatic hydrocarbon extraction treatment to obtain non-aromatic hydrocarbon raffinate oil 116, benzene-rich product 117 and toluene component 118, wherein the conditions of the aromatic hydrocarbon extraction treatment comprise the temperature of 121 ℃ and the pressure of 0.08MPa, and the stripping medium is sulfolane solvent.
The raw oil and the product index are shown in Table 1.
Comparative example 1
As shown in fig. 2, the method for producing benzene in the combined process comprises the following steps:
S1, feeding raw oil 104 consisting of straight-run heavy naphtha 100, catalytic cracking raffinate 102 and other hydrogenated naphtha 103 into a pre-hydrogenation device 1 for pre-hydrogenation reaction to obtain a pre-hydrogenation reaction product 110, wherein the pre-hydrogenation reaction condition comprises that the reaction temperature is 320 ℃, the reaction pressure is 2.8MPa, the hydrogen partial pressure is 2.52MPa, and the volume ratio of the first part of reformed hydrogen 201 to the pre-hydrogenation reaction product 110 is 90:1. The hydrogen consumption was 0.13% by weight.
S2, enabling the pre-hydrogenation reaction product 110 to enter the reforming device 4 for reforming reaction to obtain the rich reformate 112 and reformed hydrogen. The reaction pressure of the reforming treatment is 0.35MPa, the inlet temperature of the reactor is 536 ℃, and the reaction space velocity is 1.5h-1. The first partially reformed hydrogen 201 was fed (3.23 wt%) to the pre-hydrogenation apparatus 1, and the second partially reformed hydrogen 202 (96.77 wt%) and the outsourced hydrogen 207 were fed to the aromatic hydrocarbon dealkylation apparatus 6, and less than 1.0 ten thousand tons/year of hydrogen was supplemented with the outsourced hydrogen 207.
S3, enabling the reformate 112 to enter a second separation device 5 to obtain reformed C6-7 naphtha 113, C8 aromatic hydrocarbon 204, C9+ aromatic hydrocarbon 114 and heavy aromatic hydrocarbon 205, wherein the C8 aromatic hydrocarbon 204 and the heavy aromatic hydrocarbon 205 are taken as products for take-out, and the separation requirement of the second separation device 5 comprises that the content of C8+ components in the reformed C6-7 naphtha 113 is below 0.1 wt% and the content of C10+ components in the C9+ aromatic hydrocarbon 114 is below 2 w%.
S4, enabling the C9+ aromatic hydrocarbon 114 to enter an aromatic hydrocarbon dealkylation device 6 for dealkylation treatment to obtain second benzene-rich aromatic hydrocarbon 115. The dealkylation conditions included a temperature of 420 ℃, a pressure of 3.6MPa, a hydrogen partial pressure of 2.52MPa, and a hydrogen-oil volume ratio of 3.0:1.
S5, enabling reformed C6-7 naphtha 113 and second benzene-rich aromatic 115 to enter an aromatic extraction device 7 for aromatic extraction treatment to obtain non-aromatic raffinate oil 116, a benzene-rich product 117 and a toluene component 118, enabling the toluene component 118 to return to an aromatic dealkylation device 6, wherein the conditions of the aromatic extraction treatment comprise that the temperature is 121 ℃, the pressure is 0.08MPa, and the stripping medium is sulfolane solvent.
The raw oil and the product index are shown in Table 1.
Table 1 raw oil and product index in examples and comparative examples
As can be seen from the data in Table 1, the benzene-rich products produced in example 1 and comparative example 1 are identical in amount and can meet the requirements of the target products. Example 1 saves 2.6 ten thousand tons/year of hydrogen consumption compared with comparative example 1, has 43.35 ten thousand tons/year of toluene yield in the product, and has 37.87 ten thousand tons/year of naphtha.
Test case
In the economic analysis, the price of raw oil and products is calculated by adopting a system of two cross rate grids, namely 60 dollars (called middle petrochemical 60 dollars for short) and 2017-2019 average price (called average price for short) of benefit measuring price of technical economic parameters and data (2020) through the feasibility study of China petrochemical project of the institute. The construction investment of example 1 was comparable to that of comparative example 1, so that the economic analysis did not take into account the investment cost impact, and the plant operating costs contained only the plant utility costs, and did not contain catalyst and auxiliary material consumption costs. Wherein "+" means an increase from the reference value and "-" means a decrease from the reference value, for example "+26751" in table 2 means that the product yield in example 1 is increased by 26751 ten thousand yuan from the reference value of comparative example 1.
The economic comparison results of example 1 and comparative example 1 are listed in tables 2 and 3. As can be seen from table 2, example 1 increases by 42688 ten thousand yuan per year for the medium petrochemical 60 dollar price system, and increases by 46868 ten thousand yuan per year for the medium petrochemical 2017-2019 average price.
Table 2 economic comparison of example 1 with comparative example 1 (petrochemical 60 dollars in)
| Name of the name | Unit (B) | Example 1 | Comparative example 1 |
| Product yield value | Ten thousands yuan/year | +26751 | Datum |
| Cost of raw materials | Ten thousands yuan/year | -30311 | Datum |
| Cost of operation | Ten thousands yuan/year | +14374 | Datum |
| Muli (Maoli) | Ten thousands yuan/year | 42688 | Datum |
Table 3 economic comparison results (average price in 2017-2019) of example 1 and comparative example 1
| Name of the name | Unit (B) | Example 1 | Comparative example 1 |
| Product yield value | Ten thousands yuan/year | +35356 | Datum |
| Cost of raw materials | Ten thousands yuan/year | -25886 | Datum |
| Cost of operation | Ten thousand yuan | +14374 | Datum |
| Muli (Maoli) | Ten thousands yuan/year | 46868 | Datum |
As shown in tables 1-3, comparing the data of example 1 with the data of comparative example 1, the technical scheme of the present disclosure can reduce the hydrogen consumption and the naphtha yield and simultaneously improve the toluene yield, and the technical scheme of the present disclosure can not only reduce the raw material cost, but also increase the product yield, and exhibits good economic benefits.
The preferred embodiments of the present disclosure have been described in detail above with reference to the accompanying drawings, but the present disclosure is not limited to the specific details of the embodiments described above, and various simple modifications may be made to the technical solutions of the present disclosure within the scope of the technical concept of the present disclosure, and all the simple modifications belong to the protection scope of the present disclosure.
In addition, the specific features described in the above embodiments may be combined in any suitable manner without contradiction. The various possible combinations are not described further in this disclosure in order to avoid unnecessary repetition.
Moreover, any combination between the various embodiments of the present disclosure is possible as long as it does not depart from the spirit of the present disclosure, which should also be construed as the disclosure of the present disclosure.