A method for increasing the yield of liquefied gas while reducing the olefin content of gasoline

Abstract

The application discloses a method for increasing liquefied gas and reducing the content of gasoline olefins, which comprises the following steps: S1, connecting a branch with a regulating valve on the pipeline from crude gasoline of a non-MIP process system to an absorption and stabilization system; S2, respectively measuring the content of crude gasoline olefins produced by the non-MIP process system and the MIP process system; and S3, making the crude gasoline produced by the non-MIP process system enter the bottom of a riser of the MIP process system along the branch, and controlling the flow of the crude gasoline produced by the non-MIP process system to be 1% to 10% of the flow of the riser feed of the MIP process system through the regulating valve. The application is simple and easy to operate, overcomes technical bias, greatly reduces the content of catalytic cracking gasoline olefins, and can reduce the content of gasoline olefins by more than 4 percent points through a large number of experimental verifications. More than 30% of the amount of the recycled gasoline can be converted into liquefied gas products. The method does not cause adverse effects on the product quality and product properties of the original MIP process system, and does not affect the normal operation of the original MIP process system.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of petroleum refining, in particular to a method for increasing liquefied gas production and reducing the olefin content of gasoline. BACKGROUND

[0002] With the gradual upgrading of gasoline quality standards, the requirement for olefin content in finished gasoline is becoming lower and lower; in China, the proportion of catalytic cracking unit gasoline in the finished gasoline pool can reach more than 70%, and the olefin in catalytic cracking gasoline accounts for about 90% of the olefin content in finished gasoline, so in order to reduce the olefin content of finished gasoline, the olefin content of gasoline produced by the catalytic cracking unit must be reduced;

[0003] With the gradual increase in the sales of electric vehicles, the growth rate of gasoline consumption has gradually slowed down, while the demand for chemical products such as polypropylene is still strong, and 30% of the propylene production in China comes from liquefied gas produced by catalytic cracking units, so in order to improve the economic benefits of the refinery and ensure smooth product outlets, measures need to be taken to convert part of the gasoline into more popular liquefied gas products;

[0004] In most refineries, the main measures to reduce the olefin content of catalytic cracking gasoline include using olefin-reducing additives, reducing the reaction temperature, improving the properties of the raw material, and improving the activity of the catalyst, etc. These measures have two disadvantages, one is that the reduction in the olefin content of gasoline is limited, usually no more than 1.5 percentage points, and the other is that reducing the olefin content of gasoline will lead to a decrease in liquefied gas production, which will adversely affect the operating efficiency of the refinery; the above defects are problems that need to be solved by those skilled in the art;

[0005] The existing literature (Chemical Engineer, September 2013) discloses the effect of crude gasoline into the riser modification on the olefin and product distribution of gasoline, in which the crude gasoline is recycled to the riser of the original catalytic cracking unit, which reduces the olefin content of gasoline, but also leads to a decrease in economic benefits. SUMMARY

[0006] In order to overcome the deficiencies in the background art, the present application discloses a method for increasing liquefied gas production and reducing the olefin content of gasoline.

[0007] To achieve the above-mentioned application purposes, the present application adopts the following technical solutions:

[0008] A method for increasing liquefied gas production and reducing the olefin content of gasoline, comprising two sets of catalytic cracking systems, one of which is an MIP process system, and the other is a non-MIP process system, the crude gasoline produced by the MIP process system has a low olefin content, and the crude gasoline produced by the non-MIP process system has a high olefin content; comprising the following steps:

[0009] S1, connecting a branch with a regulating valve on the pipeline of the crude gasoline from the non-MIP process system to the absorption and stabilization system, the other end of the branch being communicated with the bottom of the riser of the MIP process system or with the pre-lift steam line of the bottom of the riser of the MIP process system;

[0010] S2, respectively determining the content of the olefin in the crude gasoline produced by the non-MIP process system and the MIP process system;

[0011] S3, if the difference between the contents of the olefin in the crude gasoline produced by the non-MIP process system and the MIP process system is not less than 5%, then the regulating valve of the branch in step S1 is opened, and the crude gasoline produced by the non-MIP process system enters the bottom of the riser of the MIP process system along the branch, and the flow of the crude gasoline produced by the non-MIP process system is controlled by the regulating valve to be 1% to 10% of the flow of the feed of the riser of the MIP process system.

[0012] Preferably, the flow of the crude gasoline produced by the non-MIP process system is controlled to be 5% of the flow of the feed of the riser of the MIP process system in step S3.

[0013] Due to the technical scheme as described above, the present application has the following beneficial effects:

[0014] The method for increasing the production of liquefied gas and reducing the content of olefin in gasoline disclosed by the present application is simple and easy to operate, overcomes technical bias, greatly reduces the content of olefin in catalytic cracking gasoline, and can reduce the content of olefin in gasoline by more than 4% through a large number of experiments, more than 30% of the amount of the refined gasoline can be converted into liquefied gas products, and the economic benefits of the products are improved; and the method will not adversely affect the product quality and product properties of the original MIP process system, and will not affect the normal operation of the original MIP process system. BRIEF DESCRIPTION OF DRAWINGS

[0015] Figure 1 The figure is a schematic diagram of the system connection of the present application.

[0016] In the figure: 1, crude gasoline tank; 2, crude gasoline pump; 3, stabilization regulating valve; 4, riser; 5, pre-lift steam line. DETAILED DESCRIPTION

[0017] The present application can be explained in detail through the following examples, and the purpose of the present application is to protect all technical improvements within the scope of the present application. In the description of the present application, it should be understood that the orientation or position relationship indicated by the terms "up", "down", "front", "back", "left", "right" and the like only corresponds to the drawings of the present application, and is for the convenience of describing the present application, but does not indicate or imply that the indicated device or element must have a specific orientation.

[0018] Embodiment 1, a method for increasing liquefied gas production while reducing the olefin content of gasoline, comprising two sets of catalytic cracking systems, one of which is a MIP process system and the other is a non-MIP process system, the crude gasoline produced by the MIP process system has a low olefin content, and the crude gasoline produced by the non-MIP process system has a high olefin content; comprising the following steps:

[0019] S1, connecting a branch with a regulating valve on the pipeline from the crude gasoline of the non-MIP process system to the absorption stabilization system, the other end of the branch is connected to the bottom of the riser of the MIP process system or the pre-lift steam line of the bottom of the riser of the MIP process system;

[0020] S2, respectively measuring the olefin content of the crude gasoline produced by the non-MIP process system and the MIP process system;

[0021] S3, if the difference between the olefin content of the crude gasoline produced by the non-MIP process system and the MIP process system is not less than 5 percentage points, the regulating valve of the branch in step S1 can be opened, and the crude gasoline produced by the non-MIP process system enters the bottom of the riser of the MIP process system along the branch, and the crude gasoline produced by the non-MIP process system is mixed with the fresh feed at the bottom of the riser of the MIP process system, the flow of the crude gasoline produced by the non-MIP process system is controlled by the regulating valve to be 1% to 10% of the flow of the fresh feed into the riser of the MIP process system; while mixing, ensure that the compressor, absorption stabilization system and gas desulfurization system of the MIP process system are running within the safe load; the flow of the crude gasoline into the bottom of the riser of the MIP process system can be adjusted according to the stable gasoline olefin content or the liquefied gas production, if the stable gasoline olefin content is low, the flow is reduced; if the liquefied gas production is increased, the flow is increased; preferably, the flow of the crude gasoline produced by the non-MIP process system into the bottom of the riser of the MIP process system is 5% of the flow of the fresh feed into the riser of the MIP process system;

[0022] The drawings are combined Figure 1The crude gasoline in the crude gasoline tank 1 of the non-MIP process system is sent to the absorption stabilizing system through a pipeline, a crude gasoline pump 2 for pressure boosting and a stabilizing regulating valve 3 for stabilizing flow are arranged in the pipeline, one end of a branch connected to the pipeline between the crude gasoline pump 2 and the stabilizing regulating valve 3 is communicated with the bottom of a riser 4 of the MIP process system or a pre-lift steam line 5 at the bottom of the riser 4 of the MIP process system, so that the crude gasoline produced by the non-MIP process system can be mixed into the raw material at the bottom of the riser 4 of the MIP process system, the crude gasoline produced by the non-MIP process system is contacted with the catalyst with higher activity in the MIP process system, the conversion of olefins in the crude gasoline is promoted, the content of olefins in the crude gasoline is reduced, and the cracking reaction of the fresh raw material in the MIP process system is not adversely affected, and at the bottom of the riser 4, the crude gasoline can be converted into a large amount of liquefied gas product, so that the yield of the liquefied gas is improved; a large amount of experimental verification results show that the content of olefins in the crude gasoline can be reduced by more than 4 percent, and more than 30% of the amount of the crude gasoline at the bottom of the riser 4 can be converted into the liquefied gas product.

[0023] The parts of the application not described in detail are prior art, and it is obvious for those skilled in the art that the application is not limited to the details of the above exemplary embodiments, and the application can be implemented in other specific forms without departing from the spirit or essential characteristics of the application; therefore, from any point of view, the embodiments should be regarded as exemplary and non-limiting, and all changes falling within the meaning and scope of the equivalent elements are intended to be included in the application.

Claims

1. A method for increasing the yield of liquefied gas while reducing the olefin content of gasoline, comprising two sets of catalytic cracking systems, one of which is a MIP process system and the other is a non-MIP process system, the MIP process system producing a crude gasoline with a low olefin content and the non-MIP process system producing a crude gasoline with a high olefin content; characterized in that: The method comprises the following steps: ​ S1, connecting a branch with a regulating valve on the pipeline from the crude gasoline of the non-MIP process system to the absorption and stabilization system, the other end of the branch being communicated with the bottom of the riser of the MIP process system or with the pre-lift steam line of the bottom of the riser of the MIP process system; S2, respectively measuring the content of the olefin in the crude gasoline produced by the non-MIP process system and the MIP process system; S3, if the difference between the contents of the olefin in the crude gasoline produced by the non-MIP process system and the MIP process system is not less than 5%, then the regulating valve of the branch in step S1 is opened, the crude gasoline produced by the non-MIP process system enters the bottom of the riser of the MIP process system along the branch, and the flow of the crude gasoline produced by the non-MIP process system is controlled by the regulating valve to be 1%-10% of the flow of the feed of the riser of the MIP process system.

2. The method of claim 1 wherein the yield of the liquefied gas is increased and the olefin content of the gasoline is reduced simultaneously. In step S3, the flow of the crude gasoline produced by the non-MIP process system is controlled to be 5% of the flow of the feed of the riser of the MIP process system.

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