n-Butane Isomerization System

Abstract

The invention provides a normal butane isomerization system, which belongs to the technical field of oil and gas deep processing. A raw material buffer tank, a light hydrocarbon removal tower, a hydrogenation reactor, an isomerization reactor, an isobutane stabilization tower and an isobutane separation tower connected by pipelines are provided, and the top gas phase of the isobutane stabilization tower is connected to the raw material buffer tank. The raw material normal butane is removed from the light hydrocarbon removal tower to remove light components, and after the hydrogenation reaction product is saturated with olefin substances, it is sent to the isomerization reactor, and an isomerization reaction is carried out under the action of a catalyst. The isomerization reaction product is discharged into the isobutane stabilization tower, and the C4 and above components are discharged from the tower kettle of the isobutane stabilization tower to the isobutane separation tower to separate the isobutane component. The light component gas phase at the top of the isobutane stabilization tower is passed into the raw material buffer tank to recover isobutane. According to detection, about 75% of the total amount of isobutane in the gas phase at the top of the isobutane stabilization tower can be recovered, greatly reducing the waste of the isobutane component.

Description

Technical Field

[0001] The invention belongs to the technical field of oil and gas deep processing, and particularly relates to a normal butane isomerization system. Background Art

[0002] Isomerization of n-butane to produce isobutane is an important oil and gas deep processing technology. The isobutane product produced is one of the raw materials for producing high-octane gasoline. At the same time, isobutane is also one of the important raw materials for preparing gasoline additives methyl tert-butyl ether and ethyl tert-butyl ether.

[0003] The process of isomerizing n-butane to produce isobutane mainly includes the processes of removing light components from raw materials, hydrogenating unsaturated olefins in saturated raw materials, isomerizing in the presence of a catalyst, and separating isomerized products. For example, the Chinese invention patent No. 201610256689.3 discloses a device and method for preparing isobutane, which includes a pre-light removal tower, a hydrogenation reactor, a light removal tower, an isobutane finished tower, and an isomerization reactor, etc., to realize the process of preparing isobutane from C4 raw materials through a hydroisomerization reaction.

[0004] In actual production, the top gas phase of the light-removal tower is sent to the gas furnace for incineration, and the top gas phase of the isobutane flat tower is incinerated as fuel gas. However, according to testing, the top gas phase of the isobutane finished tower contains about 50%-60% isobutane components. If it is directly incinerated, a large amount of isobutane will be wasted, reducing the comprehensive utilization rate of oil and gas. Summary of the invention

[0005] In view of this, the present invention provides a normal butane isomerization system to solve the technical problem in the prior art that isobutane is directly incinerated in the gas phase of a flat tower, resulting in a large amount of isobutane waste.

[0006] The technical solution adopted by the present invention to solve its technical problem is:

[0007] A normal butane isomerization system, comprising a raw material buffer tank, a light hydrocarbon removal tower, a hydrogenation reactor, an isomerization reactor, an isobutane stabilization tower and an isobutane separation tower connected by pipelines;

[0008] The raw material buffer tank is connected to a n-butane feed pipe, and the gas phase of the raw material buffer tank is connected to a dry gas collecting pipe;

[0009] The feed end of the light hydrocarbon removal tower is connected to the raw material buffer tank, and the discharge end is connected to the feed end of the hydrogenation reactor;

[0010] The feed end of the hydrogenation reactor is also connected to a hydrogen feed pipe, the feed end of the isomerization reactor is connected to the discharge end of the hydrogenation reactor, and the feed end of the isomerization reactor is also connected to the hydrogen feed pipe;

[0011] The feed end of the isobutane stabilization tower is connected to the discharge end of the isomerization reactor, the top gas phase of the isobutane stabilization tower is connected to the raw material buffer tank, and the feed end of the isobutane separation tower is connected to the discharge end of the bottom of the isobutane stabilization tower.

[0012] Preferably, the light hydrocarbon removal tower is also connected to a propane liquefied gas recovery pipe.

[0013] Preferably, the top gas phase of the isobutane stabilization tower is also connected to a gas phase alkali washing tower, and the discharge end of the gas phase alkali washing tower is connected to the raw material buffer tank.

[0014] Preferably, the bottom of the isobutane separation tower is connected with a heavy component collecting pipe fitting.

[0015] Preferably, a normal butane recovery pipe is provided at the top of the isobutane separation tower, and the normal butane recovery pipe is connected to the feed end of the hydrogenation reactor.

[0016] Preferably, a hydrogen dryer and a hydrogenation product dryer are provided at the feed end of the isomerization reactor.

[0017] It can be seen from the above technical scheme that the present invention provides a n-butane isomerization system, which has the following beneficial effects: a raw material buffer tank, a light hydrocarbon removal tower, a hydrogenation reactor, an isomerization reactor, an isobutane stabilization tower and an isobutane separation tower connected by pipelines are provided, wherein the top gas phase of the isobutane stabilization tower is connected to the raw material buffer tank, and the raw material n-butane first enters the raw material buffer tank for pre-light removal, and then enters the light hydrocarbon removal tower to separate and remove C3 and below components in the raw material n-butane. The bottom liquid of the light hydrocarbon removal tower is sent to the hydrogenation reactor for pre-hydrogenation reaction to saturate the olefinic substances contained in the raw material n-butane. The reaction product in the hydrogenation reactor is dried and dehydrated, and then introduced into the isomerization reactor together with dry hydrogen, and isomerization reaction is carried out under the action of a catalyst to produce isobutane. The isomerization reaction product in the isomerization reactor is discharged into the isobutane stabilization tower, and the light component is discharged from the top of the isobutane stabilization tower, and the C4 and above components are discharged from the bottom of the isobutane stabilization tower to the isobutane separation tower to separate the isobutane component. The light component gas phase discharged from the top of the isobutane stabilization tower is passed into the raw material buffer tank, and the liquid phase in the raw material buffer tank is used to capture the isobutane component in the gas phase at the top of the isobutane stabilization tower, and the isobutane in the gas phase at the top of the isobutane stabilization tower is recovered to reduce the waste of isobutane. At the same time, the gas phase at the top of the isobutane stabilization tower is stripped to accelerate the volatilization of the light component in the raw material n-butane. According to the test, about 75% of the total amount of isobutane in the gas phase at the top of the isobutane stabilization tower can be recovered through the raw material buffer tank, which greatly reduces the waste of isobutane components. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 It is the process flow diagram of the n-butane isomerization system.

[0019] In the figure: n-butane isomerization system 10, raw material buffer tank 100, n-butane feed pipe 110, light hydrocarbon removal tower 200, propane liquefied gas recovery pipe 210, hydrogenation reactor 300, hydrogen feed pipe 310, isomerization reactor 400, hydrogen dryer 410, hydrogenation product dryer 420, isobutane stabilization tower 500, gas phase alkali washing tower 510, isobutane separation tower 600, heavy component collection pipe 610, n-butane recovery pipe 620, dry gas collection pipe 700. DETAILED DESCRIPTION

[0020] The technical solutions and technical effects of the embodiments of the present invention are further described in detail below in conjunction with the accompanying drawings of the present invention.

[0021] Please see Figure 1 In a specific embodiment, a normal butane isomerization system 10 includes a raw material buffer tank 100, a light hydrocarbon removal tower 200, a hydrogenation reactor 300, an isomerization reactor 400, an isobutane stabilization tower 500 and an isobutane separation tower 600 connected by pipelines.

[0022] The raw material buffer tank 100 is used to preliminarily remove light components from the raw material n-butane. The raw material buffer tank 100 is connected to a n-butane feed pipe 110, and the gas phase of the raw material buffer tank 100 is connected to a dry gas collecting pipe 700. The raw material n-butane first enters the raw material buffer tank 100, and under a slightly negative pressure state, C3 and below light components are preliminarily separated, and the light components enter the dry gas collecting pipe 700 and are incinerated as fuel gas. C4 and above components are sent to the light hydrocarbon removal tower 200.

[0023] The feed end of the light hydrocarbon removal tower 200 is connected to the raw material buffer tank 100, and the discharge end is connected to the feed end of the hydrogenation reactor 300. The light hydrocarbon removal tower 200 is used to further remove light components in the raw material n-butane. In one embodiment, the top gas phase of the light hydrocarbon removal tower 200 is connected to the dry gas collecting pipe 700, so that the top gas phase of the light hydrocarbon removal tower 200 is used as fuel gas to recycle the calorific value of the light components. In another embodiment, the top gas phase of the light hydrocarbon removal tower 200 is also connected to a propane liquefied gas recovery pipe 210, and the propane liquefied gas recovery pipe 210 is used to recover the C3 component in the raw material n-butane, and recycle the C3 component as liquefied gas, thereby further improving the added value of the product.

[0024] The feed end of the hydrogenation reactor 300 is also connected to a hydrogen feed pipe 310, and the feed end of the isomerization reactor 400 is connected to the discharge end of the hydrogenation reactor 300, and the feed end of the isomerization reactor 400 is also connected to the hydrogen feed pipe 310. In the light hydrocarbon removal tower 200, the raw material n-butane after deep removal of light components is sent to the hydrogenation reactor 300, and hydrogen is introduced into the hydrogenation reactor 300. In the presence of a hydrogenation catalyst, a hydrogenation reaction is carried out to saturate the unsaturated hydrocarbon compounds in the raw material n-butane. The hydrogenation reaction product is sent to the isomerization reactor 400, and hydrogen is introduced into the isomerization reactor 400. Under the action of the isomerization reaction catalyst, an isomerization reaction occurs to produce isobutane. In one embodiment, in order to prevent the isomerization catalyst from being poisoned and to extend the life of the isomerization reaction catalyst, a hydrogen dryer 410 and a hydrogenation product dryer 420 are provided at the feed end of the isomerization reactor 400 to further dry the feed of the isomerization reactor 400 and reduce the water content of the feed of the isomerization reactor 400, thereby reducing the risk of poisoning of the isomerization catalyst.

[0025] The feed end of the isobutane stabilization tower 500 is connected to the discharge end of the isomerization reactor 400, the top gas phase of the isobutane stabilization tower 500 is connected to the raw material buffer tank 100, and the feed end of the isobutane separation tower 600 is connected to the discharge end of the bottom of the isobutane stabilization tower 500. After the isomerization reaction is completed, the isomerization reaction product is sent to the isobutane stabilization tower 500 for separation of light and heavy components. C3 and below light components and part of the normal butane and isobutane components are discharged from the top of the isobutane stabilization tower 500 and discharged into the raw material buffer tank 100, and the normal butane and isobutane components therein are recovered, and the light components are discharged from the gas phase of the raw material buffer tank 100 into the dry gas collection pipe 700 as fuel gas to recover the calorific value of the light components.

[0026] As shown in Table 1, the composition of the gas phase at the top of the isobutane stabilization tower 500 and the composition of the gas phase in the raw material buffer tank 100 were analyzed and found that after the gas phase at the top of the isobutane stabilization tower 500 was captured and absorbed by the liquid phase in the raw material buffer tank 100, the isobutane content in the exhaust phase was greatly reduced, and the recovery rate of isobutane reached about 75%, which greatly reduced the waste of isobutane resources. At the same time, the inlet and outlet of the raw material buffer tank 100 were kept closed, and after the gas phase at the top of the isobutane stabilization tower 500 passed through the raw material buffer tank 100, the liquid level of the raw material buffer tank 100 rose slowly. , It rose by about 3% every day. As shown in Table 2, the composition of the materials in the raw material buffer tank 100 was analyzed and found that the isobutane component content of the materials in the raw material buffer tank 100 increased significantly, while the content of C3 and below light components decreased.

[0027] Table 1 Comparison of the composition of the gas phase at the top of the isobutane stabilization tower and the gas phase composition of the raw material buffer tank

[0028]

[0029]

[0030] Table 2 Raw material n-butane components and material composition in the raw material buffer tank after isobutane recovery

[0031] Raw material n-butane Materials in the raw material buffer tank n-Butane 95.8％ 93.5％ Isobutane 1.2％ 4.2％ C1C2 0.9％ 0.8％ C3 1.5％ 1.0％

[0032] In one embodiment, the gas phase at the top of the isobutane stabilization tower 500 is further connected to a gas phase alkali washing tower 510, and the discharge end of the gas phase alkali washing tower 510 is connected to the raw material buffer tank 100. The gas phase discharged from the top of the isobutane stabilization tower 500 is alkali washed to reduce the content of acidic gases in the gas phase, such as hydrogen sulfide or hydrogen chloride, to prevent the acidic gases from affecting the service life of the hydrogenation catalyst and the isomerization catalyst.

[0033] In another embodiment, the bottom of the isobutane separation tower 600 is connected to a heavy component collecting pipe 610 to collect and discharge C5 and above heavy components in the bottom of the isobutane separation tower 600 .

[0034] In another embodiment, a normal butane recovery pipe 620 is disposed at the top of the isobutane separation tower 600, and the normal butane recovery pipe 620 is connected to the feed end of the hydrogenation reactor 300 to recycle the normal butane component that has not been completely reacted.

[0035] What is disclosed above is only a preferred embodiment of the present invention, which certainly cannot be used to limit the scope of rights of the present invention. A person skilled in the art can understand that all or part of the processes of the above embodiments and equivalent changes made according to the claims of the present invention still fall within the scope of the invention.

Claims

1. A n-butane isomerization system, characterized in that: It includes a raw material buffer tank, a light hydrocarbon removal tower, a hydrogenation reactor, an isomerization reactor, an isobutane stabilization tower and an isobutane separation tower connected by pipelines; The raw material buffer tank is connected to a normal butane feed pipe, and the gas phase of the raw material buffer tank is connected to a dry gas collecting pipe; the feed end of the light hydrocarbon removal tower is connected to the raw material buffer tank, and the discharge end is connected to the feed end of the hydrogenation reactor; the feed end of the hydrogenation reactor is also connected to a hydrogen feed pipe, the feed end of the isomerization reactor is connected to the discharge end of the hydrogenation reactor, and the feed end of the isomerization reactor is also connected to the hydrogen feed pipe; The feed end of the isobutane stabilization tower is connected to the discharge end of the isomerization reactor, the top gas phase of the isobutane stabilization tower is connected to the raw material buffer tank, and the feed end of the isobutane separation tower is connected to the discharge end of the bottom of the isobutane stabilization tower; after the isomerization reaction is completed, the isomerization reaction product is sent to the isobutane stabilization tower to separate the light and heavy components, and the light components of C3 and below and part of the normal butane and isobutane components are discharged from the top of the isobutane stabilization tower to the raw material buffer tank, so as to recover the normal butane and isobutane components therein from the raw material buffer tank; The top gas phase of the isobutane stabilization tower is also connected to a gas phase alkali washing tower, and the discharge end of the gas phase alkali washing tower is connected to the raw material buffer tank; the top of the isobutane separation tower is provided with a normal butane recovery pipe fitting, and the normal butane recovery pipe fitting is connected to the feed end of the hydrogenation reactor.

2. The n-butane isomerization system according to claim 1, characterized in that: The light hydrocarbon removal tower is also connected with a propane liquefied gas recovery pipe.

3. The n-butane isomerization system according to claim 1, characterized in that: The tower kettle of the isobutane separation tower is connected with a heavy component collecting pipe fitting.

4. The n-butane isomerization system according to claim 1, characterized in that: The feed end of the isomerization reactor is provided with a hydrogen dryer and a hydrogenation product dryer.

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