CN-119979217-B - Low-temperature alkylation method and device using isomerism carbon five and isomerism carbon four as raw materials

CN119979217BCN 119979217 BCN119979217 BCN 119979217BCN-119979217-B

Abstract

The invention relates to the technical field of gasoline processing, in particular to a low-temperature alkylation method and a device which take isomerism carbon five and isomerism carbon four as raw materials, wherein the method comprises the following steps that firstly, the etherified carbon four enters a carbon four isomerisation unit to carry out isomerisation reaction of carbon four olefins to obtain isomerism carbon four; and thirdly, mixing the isomeric carbon four and the isomeric carbon five, then entering a low-temperature alkylation reaction unit, and carrying out alkylation reaction under the catalysis of concentrated sulfuric acid, and separating reaction products to obtain isobutane, n-butane and alkylated gasoline. The invention effectively solves the problems of increased acid consumption, increased dry point of the alkylate product, increased sulfur content and the like in the alkylation process, realizes reasonable utilization of the carbon four-isomerization unit and the carbon five-isomerization unit, and provides high-quality raw materials for alkylation while increasing the yield of MTBE and etherified gasoline, thereby being an effective quality improvement and efficiency improvement means.

Inventors

CAI HAIJUN
GUO LINCHAO
HE DONG
YIN JIGUO
WU KE
LI JIAN

Assignees

中国石油天然气股份有限公司

Dates

Publication Date: 20260512
Application Date: 20231110

Claims (5)

1. The low-temperature alkylation method taking the isomerism carbon five and the isomerism carbon four as raw materials is characterized by comprising the following steps: Firstly, enabling the etherified carbon four to enter a carbon four isomerization unit for carrying out a carbon four olefin isomerization reaction to obtain an isomeric carbon four; Secondly, enabling the etherified carbon five to enter a carbon five isomerization unit for carrying out carbon five olefin isomerization reaction to obtain isomeric carbon five; Step three, mixing the four and five isomeric carbon atoms, then entering 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; in the first step, the technological conditions of the isomerization reaction of the carbon tetraolefin are that the reaction temperature is 330 ℃ and the reaction pressure is 0.3MPa; In the second step, the technological conditions of the isomerization reaction of the carbon pentaolefin are that the reaction temperature is 335 ℃ and the reaction pressure is 0.3MPa; In the third step, the feeding ratio of the isomeric carbon four to the isomeric carbon five is 20 (1-5), and the reaction temperature of the alkylation reaction is-4 ℃ to 4 ℃.
2. The method for low-temperature alkylation of five and four isomeric carbons according to claim 1, wherein in the third step, the acid-hydrocarbon ratio is (2.0-3.5): 1, and the mass concentration of concentrated sulfuric acid in the reaction cycle is maintained at not less than 90%.
3. The low temperature alkylation process using five and four isomeric carbons as raw materials according to claim 2, wherein in the third step, the separated isobutane is returned to the low temperature alkylation reaction unit to be recycled as a refrigerant.
4. A low-temperature alkylation device using isomerised carbon five and isomerised carbon four as raw materials for implementing the method according to any one of claims 1 to 3, which is characterized by comprising a carbon four isomerisation unit, a carbon five isomerisation unit, a low-temperature alkylation reaction unit and a rectification unit, wherein the feed end of the carbon four isomerisation unit is fixedly communicated with an etherified carbon four feed line, the feed end of the carbon five isomerisation unit is fixedly communicated with an etherified carbon five feed line, a first alkylation feed line is fixedly communicated between the discharge end of the carbon four isomerisation unit and the feed end of the low-temperature alkylation reaction unit, a second alkylation feed line is fixedly communicated between the discharge end of the carbon five isomerisation unit and the first alkylation feed line, a rectification pipeline is fixedly communicated between the discharge end of the low-temperature alkylation reaction unit and the feed end of the rectification unit, an isobutane pipeline is fixedly communicated with the first discharge end of the rectification unit, a normal butane pipeline is fixedly communicated with the second discharge end of the rectification unit, and an alkylated gasoline pipeline is fixedly communicated with the first discharge end of the rectification unit.
5. The low temperature alkylation unit of claim 4, wherein a reflux line is fixedly connected between the isobutane line and the second alkylation feed line and the first alkylation feed line between the low temperature alkylation reaction unit.

Description

Low-temperature alkylation method and device using isomerism carbon five and isomerism carbon four as raw materials Technical Field The invention relates to the technical field of gasoline processing, in particular to a low-temperature alkylation method and a device using isomerism carbon five and isomerism carbon four as raw materials. Background Along with the various standards of domestic oil product upgrading, such as national VI, beijing VI and other standards, the gasoline product standards gradually develop towards the directions of high octane number, low aromatic hydrocarbon, low olefin and low sulfur content. The reduction of the contents of a plurality of environmental protection indexes such as olefin content, aromatic hydrocarbon content, benzene content and the like can cause certain difficulty in blending gasoline. The existing carbon five-olefin resources of the oil refinery mainly enter the gasoline product in a direct blending mode, and the materials participate in the direct blending to cause the waste of low-carbon olefin. In addition, the content of olefin in the etherified carbon four in the raw material of the alkylation device is less, the average content of isobutane is about 50%, the isobutane is excessive in the alkylation reaction process, the isobutane in the isobutane outer tank throwing area is 3t/h to 5t/h, and the isobutane in the excessive reaction has to be sold in an inefficient liquefied gas after long-time accumulation. The refinery now has about 35% to 40% of post-ether carbon five and isomeric carbon five materials containing carbon four and carbon five olefins as the alkylation unit reaction olefin feedstock. On the one hand, the load of the alkylation device is increased, and rich isobutane liquefied gas is consumed. On the other hand, the octane number and the harmonicity of the increased alkylated oil product are better than the effect of directly blending the carbon five olefins into the gasoline, and the alkylation reaction of the carbon five olefins can increase the yield of the gasoline and reduce the liquefied gas, and can reduce the olefin content of the gasoline. The industrial raw materials of the alkylation device are widened through the process change, and a low-cost process technical route is provided for upgrading the quality of gasoline products of refineries. Since the alkylation device operates, the content of impurities dimethyl ether and dibutene in the raw materials is ultrahigh, so that the problems of increased acid consumption of the alkylation device, increased dry point of an alkylate product, increased sulfur content and the like can be caused, the high-load operation of the alkylation device is seriously influenced, meanwhile, the high acid consumption also restricts the processing of the carbon five-olefin raw materials, and the advantages of increasing the yield of gasoline and reducing the olefin content of the gasoline can not be fully exerted when the carbon five-olefin is processed through alkylation. This requires that the lower levels of dimethyl ether and 1, 3-butadiene of carbon four and five isomers be required after the isomerization unit. Therefore, in the present stage, the reaction feed of the alkylation device needs to be optimized and improved so as to solve the problems of increased acid consumption, increased dry point of the alkylate product, increased sulfur content and the like in the alkylation process. Chinese patent publication No. CN105601460a discloses a process for purifying an alkylated material, which comprises passing an alkylated material containing impurities through a water washing column, a dehydration column, a desulfurization column, a dechlorination column, a denitrification column, a deoxidisation, a chemical compound column, a preheater, and a selective hydrogenation reactor to obtain a purified alkylated material. The method for refining the alkylation raw material can effectively remove impurities in the alkylation raw material, obviously reduce the impurity content in the alkylation raw material, avoid the poisoning of a solid acid catalyst in the subsequent alkylation reaction, and improve the catalytic activity and the service cycle of the alkylation solid acid. However, the method has the following defects that (1) 8 towers and 1 hydrogenation reactor are needed to be added, equipment is more increased, investment is large, and occupied energy consumption is high, (2) the carbon four isomerization unit and the carbon five isomerization unit are not reasonably utilized, so that the device is idle, and (3) the hydrogenation reactor is used in the patent, new hydrogen resources are needed to be provided, and raw material cost is increased. Disclosure of Invention The invention provides a low-temperature alkylation method and a low-temperature alkylation device using isomerism carbon five and isomerism carbon four as raw materials, overcomes the defects of the prior art, and can effectively solve t