Low-temperature alkylation method and device taking isomeric C5 and isomeric C4 as raw materials

Abstract

The invention relates to the technical field of gasoline processing, in particular to a low-temperature alkylation method and device with isomerized C5 and isomerized C4 as raw materials, and the low-temperature alkylation method comprises the following steps: step 1, etherified C4 enters a C4 isomerization unit for C4 olefin isomerization reaction to obtain isomerized C4; step 2, enabling the etherified C5 to enter a C5 isomerization unit, and carrying out C5 olefin isomerization reaction to obtain isomerized C5; and 3, mixing the isomeric C4 and the isomeric C5, feeding the mixture into a low-temperature alkylation reaction unit, carrying out alkylation reaction under the catalysis of concentrated sulfuric acid, and separating reaction products to obtain isobutane, n-butane and alkylated gasoline. The method effectively solves the problems of increased acid consumption, increased dry point of an alkylated oil product, increased sulfur content and the like in an alkylation process, realizes reasonable utilization of C4 isomerization and C5 isomerization units, provides high-quality raw materials for alkylation while increasing the yield of MTBE and etherified gasoline, and is an effective quality-improving and efficiency-improving means.

Description

Technical Field

[0001] The invention relates to the technical field of gasoline processing, and is a low-temperature alkylation method and device using isomerized C5 and isomerized C4 as raw materials. Background Art

[0002] With the introduction of various standards for domestic oil product upgrades, such as the National VI and Beijing VI standards, gasoline product standards are gradually developing towards high octane number, low aromatics, low olefins, and low sulfur content. The reduction in the content of olefins, aromatics, benzene and other environmental indicators will make it difficult to blend gasoline.

[0003] The existing C5 olefin resources of the refinery are mainly used in gasoline products through direct blending, and the participation of materials in direct blending leads to waste of low-carbon olefins. In addition, the olefin content of C4 after ether in the raw materials of the alkylation unit is relatively low, and the isobutane content is about 50% on average. There is excess isobutane in the alkylation reaction process, and the isobutane is dumped in the tank area at 3t / h to 5t / h. After a long period of accumulation, the excess isobutane has to be exported as inefficient liquefied gas.

[0004] The existing etherified C5 and isomerized C5 materials containing about 35% to 40% C4 and C5 olefins in the refinery are used as olefin raw materials for the alkylation unit reaction. On the one hand, the load of the alkylation unit is increased and the abundant isobutane liquefied gas is consumed. On the other hand, the octane number and blending properties of the increased alkylation oil products are better than the effect of directly blending C5 olefins into gasoline. Alkylation of C5 olefins can not only increase gasoline production and reduce liquefied gas, but also reduce the olefin content of gasoline.

[0005] By changing the process, the industrial raw materials of the alkylation unit have been broadened, providing a low-cost process technology route for upgrading the quality of gasoline products in refineries.

[0006] Since the operation of the alkylation unit, the impurity dimethyl ether and dibutylene in the raw materials have been extremely high, which will cause problems such as increased acid consumption of the alkylation unit, increased dry point of the alkylation oil product, and increased sulfur content, which seriously affects the high-load operation of the alkylation unit. At the same time, high acid consumption also restricts the processing of C5 olefin raw materials. The advantages of alkylation processing of C5 olefins in increasing gasoline production and reducing gasoline olefins cannot be fully utilized. This requires that after the isomerization treatment unit, the dimethyl and 1,3-butadiene of isomerized C4 and isomerized C5 need to be at a low level. Therefore, at this stage, it is urgent to optimize and improve the reaction feed of the alkylation unit to solve the problems of increased acid consumption, increased dry point of alkylation oil products, and increased sulfur content in the alkylation process.

[0007] A Chinese patent document with publication number CN105601460A discloses a method for refining an alkylation raw material, wherein the alkylation raw material containing impurities is passed through a water washing tower, a dehydration tower, a desulfurization tower, a dechlorination tower, a denitrogenation tower, a deoxygenation tower, a compound tower, a preheater, and a selective hydrogenation reactor to obtain a refined alkylation raw material. The alkylation raw material refining method of the present invention can effectively remove impurities from the alkylation raw material, significantly reduce the impurity content in the alkylation raw material, avoid poisoning of the solid acid catalyst in the subsequent alkylation reaction, and improve the catalytic activity and service life of the alkylation solid acid. However, this method has the following shortcomings: (1) It is necessary to add 8 towers and 1 hydrogenation reactor, which increases the equipment, the investment is large, and the energy consumption is high; (2) The carbon four isomerization and carbon five isomerization units are not reasonably utilized, resulting in idle devices; (3) The patent uses a hydrogenation reactor, which requires the provision of new hydrogen resources, and the cost of raw materials increases. Summary of the invention

[0008] The present invention provides a low-temperature alkylation method and apparatus using isomerized C5 and isomerized C4 as raw materials, which overcomes the deficiencies of the above-mentioned prior art and can effectively solve the problems of increased acid consumption, increased dry point of alkylate oil products and increased sulfur content in the prior art alkylation process.

[0009] One of the technical solutions of the present invention is achieved by the following measures: A low-temperature alkylation method using isomerized C5 and isomerized C4 as raw materials is carried out according to the following steps: In the first step, the etherified C4 enters the C4 isomerization unit to undergo C4 olefin isomerization reaction to obtain isomerized C4; In the second step, the etherified C5 enters the C5 isomerization unit to undergo C5 olefin isomerization reaction to obtain isomerized C5; In the third step, the isomerized C4 and C5 are mixed and then enter the low-temperature alkylation reaction unit. Under the catalysis of concentrated sulfuric acid, an alkylation reaction occurs, and the reaction products are separated to obtain isobutane, normal butane and alkylated gasoline.

[0010] The following is a further optimization and / or improvement of one of the above-mentioned technical solutions: In the first step above, the process conditions for the isomerization reaction of C4 olefins are: reaction temperature is 330°C and reaction pressure is 0.3MPa.

[0011] In the above second step, the process conditions for the isomerization reaction of C5 olefins are: reaction temperature is 335°C and reaction pressure is 0.3MPa.

[0012] In the above third step, the feed ratio of isomerized C4 and isomerized C5 is 20:1 to 5.

[0013] In the third step, the reaction temperature of the alkylation reaction is -4°C to 4°C.

[0014] In the third step, in the alkylation reaction, the acid-to-hydrocarbon ratio is 2.0 to 3.5:1, and the mass concentration of concentrated sulfuric acid in the reaction cycle is maintained at not less than 90%.

[0015] In the third step, the separated isobutane is returned to the low-temperature alkylation reaction unit for recycling as a refrigerant.

[0016] The second technical solution of the present invention is achieved by the following measures: a low-temperature alkylation device using isomerized C5 and isomerized C4 as raw materials, comprising a C4 isomerization unit, a C5 isomerization unit, an alkylation reaction unit, and a distillation unit, wherein the feed end of the C4 isomerization unit is fixedly connected with a C4 feed pipeline after etherification, the feed end of the C5 isomerization unit is fixedly connected with a C5 feed pipeline after etherification, a first alkylation feed pipeline is fixedly connected between the discharge end of the C4 isomerization unit and the feed end of the alkylation reaction unit, a second alkylation feed pipeline is fixedly connected between the discharge end of the C5 isomerization unit and the first alkylation feed pipeline, a distillation pipeline is fixedly connected between the discharge end of the alkylation reaction unit and the feed end of the distillation unit, an isobutane pipeline is fixedly connected to the first discharge end of the distillation unit, a normal butane pipeline is fixedly connected to the second discharge end of the distillation unit, and an alkylation gasoline pipeline is fixedly connected to the first discharge end of the distillation unit.

[0017] The following is a further optimization and / or improvement of the second technical solution of the above invention: A reflux pipeline is fixedly connected between the isobutane pipeline and the first alkylation feed pipeline between the second alkylation feed pipeline and the low-temperature alkylation reaction unit.

[0018] The present invention effectively solves the problems of increased acid consumption, increased dry point and increased sulfur content of alkylate oil products in the alkylation process, realizes the rational utilization of C4 isomerization and C5 isomerization units, reduces the idleness of devices, and provides high-quality raw materials for alkylation while increasing the production of MTBE and etherified gasoline, achieving multiple goals at one stroke, and is an effective means of improving quality and efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Attached Figure 1 This is a schematic diagram of the process flow of Example 10 of the present invention.

[0020] The codes in the accompanying drawings are: 1 is a C4 isomerization unit, 2 is a C5 isomerization unit, 3 is an alkylation reaction unit, 4 is a distillation unit, 5 is a C4 feed pipeline after etherification, 6 is a C5 feed pipeline after etherification, 7 is a first alkylation feed pipeline, 8 is a second alkylation feed pipeline, 9 is a distillation pipeline, 10 is an isobutane pipeline, 11 is a normal butane pipeline, 12 is an alkylation gasoline pipeline, and 13 is a reflux pipeline. DETAILED DESCRIPTION

[0021] The present invention is not limited by the following embodiments, and the specific implementation method can be determined according to the technical scheme of the present invention and the actual situation. Unless otherwise specified, the various chemical reagents and chemicals mentioned in the present invention are all chemical reagents and chemicals known and used in the prior art; the percentages in the present invention are all mass percentages unless otherwise specified. In the present invention, unless otherwise specified, the equipment and devices used are all equipment and devices known and used in the art.

[0022] The present invention will be further described below in conjunction with embodiments: Example 1: Figure 1 As shown, the low temperature alkylation method using isomeric C5 and isomeric C4 as raw materials is carried out according to the following steps: In the first step, the etherified C4 enters the C4 isomerization unit 1 to undergo C4 olefin isomerization reaction to obtain isomerized C4; In the second step, the etherified C5 enters the C5 isomerization unit 2 to undergo C5 olefin isomerization reaction to obtain isomerized C5; In the third step, the isomerized C4 and C5 are mixed and then enter the low-temperature alkylation reaction unit 3. Under the catalysis of concentrated sulfuric acid, an alkylation reaction occurs, and the reaction products are separated to obtain isobutane, normal butane and alkylated gasoline.

[0023] Example 2: As an optimization of the above example, in the first step, the process conditions for the isomerization reaction of C4 olefins are: reaction temperature is 330°C, and reaction pressure is 0.3 MPa (G).

[0024] Example 3: As an optimization of the above example, in the second step, the process conditions for the isomerization reaction of C5 olefins are: reaction temperature is 335°C, and reaction pressure is 0.3 MPa (G).

[0025] Example 4: As an optimization of the above example, in the third step, the feed ratio of isomerized C4 and isomerized C5 is 20:1 to 5.

[0026] Example 5: As an optimization of the above example, in the third step, the reaction temperature of the alkylation reaction is -4°C to 4°C.

[0027] Example 6: As an optimization of the above example, in the third step, in the alkylation reaction, the acid-to-hydrocarbon ratio is 2.0 to 3.5:1, and the mass concentration of concentrated sulfuric acid in the reaction cycle is maintained at not less than 90% (ie, the water and hydrocarbon content shall not be greater than 10%).

[0028] Example 7: As an optimization of the above example, in the third step, the separated isobutane is returned to the low-temperature alkylation reaction unit for recycling as a refrigerant 3.

[0029] Example 8: Figure 1As shown, the low-temperature alkylation device using isomerized C5 and isomerized C4 as raw materials comprises a C4 isomerization unit 1, a C5 isomerization unit 2, an alkylation reaction unit 3, and a distillation unit 4. The feed end of the C4 isomerization unit 1 is fixedly connected with a C4 feed pipeline 5 after etherification, the feed end of the C5 isomerization unit 2 is fixedly connected with a C5 feed pipeline 6 after etherification, a first alkylation feed pipeline 7 is fixedly connected between the discharge end of the C4 isomerization unit 1 and the feed end of the alkylation reaction unit 3, a second alkylation feed pipeline 8 is fixedly connected between the discharge end of the C5 isomerization unit 2 and the first alkylation feed pipeline 7, a distillation pipeline 9 is fixedly connected between the discharge end of the alkylation reaction unit 3 and the feed end of the distillation unit 4, an isobutane pipeline 10 is fixedly connected with the first discharge end of the distillation unit 4, a normal butane pipeline 11 is fixedly connected with the second discharge end of the distillation unit 4, and an alkylation gasoline pipeline 12 is fixedly connected with the first discharge end of the distillation unit 4.

[0030] Example 9: Figure 1 As shown, as an optimization of the above embodiment, a reflux pipeline 13 is fixedly connected between the isobutane pipeline 10 and the first alkylation feed pipeline 7 between the second alkylation feed pipeline 8 and the low-temperature alkylation reaction unit 3 .

[0031] As needed, valves and instruments that enable normal operation of the low-temperature alkylation device using isomerized C5 and isomerized C4 as raw materials are fixedly installed on each pipeline, and the C4 isomerization unit 1, the C5 isomerization unit 2, the alkylation reaction unit 3 and the distillation unit 4 all use existing reactors and equipment.

[0032] According to the needs, the isomerization reaction of the olefins of C4 and C5 after etherification is carried out under the action of an isomerization catalyst, and the isomerization catalyst can adopt the existing conventional isomerization catalyst.

[0033] The present invention provides a method and device for low-temperature alkylation using isomerized C5 and isomerized C4 as raw materials. The method uses etherified C4 and etherified C5 as raw materials to respectively perform olefin isomerization reaction to obtain isomerized C4 and isomerized C5. Isomerized C4 and isomerized C5 enter a low-temperature alkylation reaction unit 3 for reaction, and the reaction products are sent to a distillation unit 4 for separation into n-butane, isobutane and alkylated gasoline. Through the above process, dimethyl ether and 1,3-butadiene in etherified C4 and etherified C5 are significantly reduced, and acid consumption, dry point and sulfur content of alkylated oil products are all reduced. In this process, the C5 olefin in isomerized C5 and the isobutane in isomerized C4 undergo low-temperature alkylation reaction, which not only increases the production of gasoline blending components and reduces liquefied gas components, but also reduces the olefin content in the gasoline blending pool. The present invention realizes the rational utilization of the C4 isomerization unit 1 and the C5 isomerization unit 2, and reduces the idleness of the device; when realizing olefin isomerization, the C4 isomerization unit 1 and the C5 isomerization unit 2 can decompose the dimethyl ether in the raw material, and at the same time of increasing the production of MTBE and etherified gasoline, provide high-quality raw materials for alkylation, achieve multiple goals at one stroke, and is an effective means of improving quality and increasing efficiency.

[0034] Example 10: The low temperature alkylation method using isomeric C5 and isomeric C4 as raw materials is carried out according to the following steps: In the first step, the etherified C4 enters the C4 isomerization unit 1 to undergo C4 olefin isomerization reaction at a reaction temperature of 330°C and a reaction pressure of 0.3MPa to obtain isomerized C4. The content of dimethyl ether in the product isomerized C4 is 24mg / kg, and the content of 1,3-butadiene is 60mL / m³.

[0035] In the second step, the etherified C5 enters the C5 isomerization unit 2 to undergo C5 olefin isomerization reaction at a reaction temperature of 335°C and a reaction pressure of 0.3MPa (G) to obtain isomerized C5. The content of dimethyl ether in the isomerized C5 is 0mg / kg, and the content of 1,3-butadiene is 20mL / m³.

[0036] In the third step, 20 t / h of isomerized C4 feed and 3 t / h of isomerized C5 feed are mixed and enter the low-temperature alkylation reaction unit 3, where an alkylation reaction occurs under the catalysis of concentrated sulfuric acid. The alkylation reaction temperature ranges from -4°C to 4°C, the acid-to-hydrocarbon ratio is 2.5:1, and the reaction products are separated to obtain isobutane, normal butane and alkylated gasoline. In this embodiment, the conversion rate of the C5 olefin alkylation reaction is 98%, the product yield is 63%, the alkylation research octane number is 96, and the acid consumption is 115 kg / ton of alkylated gasoline.

[0037] Example 11: The low temperature alkylation method using isomeric C5 and isomeric C4 as raw materials is carried out according to the following steps: In the first step, the etherified C4 enters the C4 isomerization unit 1 to undergo C4 olefin isomerization reaction at a reaction temperature of 330°C and a reaction pressure of 0.3MPa to obtain isomerized C4. The content of dimethyl ether in the product isomerized C4 is 24mg / kg, and the content of 1,3-butadiene is 60mL / m³.

[0038] In the second step, the etherified C5 enters the C5 isomerization unit 2 to undergo C5 olefin isomerization reaction at a reaction temperature of 335°C and a reaction pressure of 0.3MPa (G) to obtain isomerized C5. The content of dimethyl ether in the isomerized C5 is 0mg / kg, and the content of 1,3-butadiene is 20mL / m³.

[0039] In the third step, 20 t / h of isomerized C4 feed and 1.5 t / h of isomerized C5 feed are mixed and enter the low-temperature alkylation reaction unit 3. Under the catalysis of concentrated sulfuric acid, an alkylation reaction occurs. The alkylation reaction temperature ranges from -4°C to 4°C, and the acid-hydrocarbon ratio is 2:1. The reaction products are separated to obtain isobutane, normal butane and alkylated gasoline. In this embodiment, the conversion rate of C5 olefin alkylation reaction is 98%, the product yield is 63%, the alkylation research octane number is 96.5, and the acid consumption is 110 kg / ton of alkylated gasoline.

[0040] Example 12: The low temperature alkylation method using isomeric C5 and isomeric C4 as raw materials is carried out according to the following steps: In the first step, the etherified C4 enters the C4 isomerization unit 1 to undergo C4 olefin isomerization reaction at a reaction temperature of 330°C and a reaction pressure of 0.3MPa to obtain isomerized C4. The content of dimethyl ether in the product isomerized C4 is 24mg / kg, and the content of 1,3-butadiene is 60mL / m³.

[0041] In the second step, the etherified C5 enters the C5 isomerization unit 2 to undergo C5 olefin isomerization reaction at a reaction temperature of 335°C and a reaction pressure of 0.3MPa (G) to obtain isomerized C5. The content of dimethyl ether in the isomerized C5 is 0mg / kg, and the content of 1,3-butadiene is 20mL / m³.

[0042] In the third step, 20 t / h of isomerized C4 feed and 5 t / h of isomerized C5 feed are mixed and then enter the low-temperature alkylation reaction unit 3, where an alkylation reaction occurs under the catalysis of concentrated sulfuric acid. The alkylation reaction temperature ranges from -4°C to 4°C, and the acid-to-hydrocarbon ratio is 3:1. The reaction products are separated to obtain isobutane, normal butane and alkylated gasoline. In this embodiment, the conversion rate of the C5 olefin alkylation reaction is 98%, the product yield is 63%, the alkylation research octane number is 95.6, and the acid consumption is 118 kg / ton of alkylated gasoline.

[0043] Comparative Example: The etherified C4 and the etherified C5 are directly mixed and subjected to low-temperature alkylation. The specific steps are as follows: Etherified C4 and etherified C5 are directly mixed and fed into the low-temperature alkylation reaction unit 3, with 23t / h of etherified C4 feed and 1.5t / h of etherified C5 feed. Alkylation reaction occurs under the catalysis of concentrated sulfuric acid. The alkylation reaction temperature ranges from -4°C to 4°C, and the acid-hydrocarbon ratio is 3:1. Alkylation gasoline is obtained after the reaction. Among them, the conversion rate of C5 olefin alkylation reaction is 96%, the alkylation research octane number is 95.0, and the acid consumption is 132kg / ton of alkylation gasoline.

[0044] After the implementation of the method of low-temperature alkylation using isomerized C5 and isomerized C4 as raw materials, the dimethyl ether and 1,3-butadiene in the etherified C4 and the etherified C5 are significantly reduced, and the problems of increased acid consumption, increased dry point of alkylated oil products and increased sulfur content are effectively solved. Under the condition of surplus isobutane, the olefin content in the C5 olefin material is between 35% and 40%. For every ton of C5 olefin material processed, about 0.38 tons of isobutane can be consumed, and the output of alkylated oil is increased by 0.72 tons (excluding unreacted C5 alkanes). The C5 olefins of the device complete the alkylation reaction under the catalysis of low-temperature sulfuric acid, rationally utilize the isobutane resources, convert the inefficient liquefied gas into efficient alkylated oil, increase the output of alkylated oil products, and form a low-cost National VI B gasoline quality upgrading process technology route.

[0045] In summary, the method of low-temperature alkylation using isomerized C5 and isomerized C4 as raw materials of the present invention effectively reduces dimethyl ether and 1,3-butadiene in etherified C4 and etherified C5, and effectively solves the problems of increased acid consumption, increased dry point of alkylated oil products and increased sulfur content. It not only increases the production of gasoline blending components and reduces liquefied gas components, but also reduces the olefin content in the gasoline blending pool. While increasing the production of MTBE and etherified gasoline, it provides high-quality raw materials for alkylation, achieves multiple goals at one stroke, and is an effective means of improving quality and efficiency.

[0046] The above technical features constitute the embodiments of the present invention, which have strong adaptability and implementation effect. Non-essential technical features can be added or reduced according to actual needs to meet the requirements of different situations.

Claims

1. A low temperature alkylation method using isomeric C5 and isomeric C4 as raw materials, characterized in that Follow these steps: In the first step, the etherified C4 enters the C4 isomerization unit to undergo C4 olefin isomerization reaction to obtain isomerized C4; In the second step, the etherified C5 enters the C5 isomerization unit to undergo C5 olefin isomerization reaction to obtain isomerized C5; In the third step, the isomerized C4 and C5 are mixed and then enter the low-temperature alkylation reaction unit. Under the catalysis of concentrated sulfuric acid, an alkylation reaction occurs, and the reaction products are separated to obtain isobutane, normal butane and alkylated gasoline.

2. The low temperature alkylation method using isomeric C5 and isomeric C4 as raw materials according to claim 1, characterized in that In the first step, the process conditions for the isomerization reaction of C4 olefins are: reaction temperature is 330°C and reaction pressure is 0.3MPa.

3. The low temperature alkylation method using isomeric C5 and isomeric C4 as raw materials according to claim 1 or 2, characterized in that In the second step, the process conditions for the isomerization reaction of C5 olefins are: reaction temperature is 335°C and reaction pressure is 0.3MPa.

4. The low temperature alkylation method using isomeric C5 and isomeric C4 as raw materials according to any one of claims 1 to 3, characterized in that In the third step, the feed ratio of isomerized C4 and isomerized C5 is 20:1 to 5.

5. The low temperature alkylation method using isomeric C5 and isomeric C4 as raw materials according to any one of claims 1 to 4, characterized in that In the third step, the reaction temperature of the alkylation reaction is -4°C to 4°C.

6. The low temperature alkylation method using isomeric C5 and isomeric C4 as raw materials according to any one of claims 1 to 5, characterized in that In the third step, in the alkylation reaction, the acid-to-hydrocarbon ratio is 2.0 to 3.5:1, and the mass concentration of concentrated sulfuric acid in the reaction cycle is maintained at not less than 90%.

7. The low temperature alkylation method using isomeric C5 and isomeric C4 as raw materials according to any one of claims 1 to 6, characterized in that In the third step, the separated isobutane is returned to the low-temperature alkylation reaction unit for recycling as a refrigerant.

8. A low temperature alkylation unit using isomerized C5 and isomerized C4 as raw materials for implementing the method according to any one of claims 1 to 7, characterized in that The invention comprises a C4 isomerization unit, a C5 isomerization unit, an alkylation reaction unit and a distillation unit. The feed end of the C4 isomerization unit is fixedly connected with a C4 feed pipeline after etherification, the feed end of the C5 isomerization unit is fixedly connected with a C5 feed pipeline after etherification, a first alkylation feed pipeline is fixedly connected between the discharge end of the C4 isomerization unit and the feed end of the alkylation reaction unit, a second alkylation feed pipeline is fixedly connected between the discharge end of the C5 isomerization unit and the first alkylation feed pipeline, a distillation pipeline is fixedly connected between the discharge end of the alkylation reaction unit and the feed end of the distillation unit, an isobutane pipeline is fixedly connected with the first discharge end of the distillation unit, a normal butane pipeline is fixedly connected with the second discharge end of the distillation unit, and an alkylation gasoline pipeline is fixedly connected with the first discharge end of the distillation unit.

9. The low temperature alkylation unit using isomerized C5 and isomerized C4 as raw materials according to claim 8, characterized in that A reflux pipeline is fixedly connected between the isobutane pipeline and the first alkylation feed pipeline between the second alkylation feed pipeline and the low-temperature alkylation reaction unit.

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