Chemical crude isopentene treatment method

Abstract

The invention discloses a chemical crude isopentene treatment method, which comprises the following steps: firstly, carrying out dimerization reaction to polymerize cyclopentadiene in C5 into dicyclopentadiene, rectifying to remove dicyclopentadiene and part of m-pentadiene, extracting and rectifying by using acetonitrile as a solvent to remove crude m-pentadiene and crude dicyclopentadiene of isoprene, and separating the crude isopentadiene from the crude m-pentadiene and the crude dicyclopentadiene to obtain crude isopentene. According to the method, high-purity isoprene is separated from C5 components with very close boiling points, crude isopentene is obtained, and the method has the technical characteristics that the additional value of the crude isopentene can be improved, the economic benefit is effectively improved and the like.

Description

Technical Field

[0001] The invention relates to a processing method, and more specifically to a chemical crude isopentene processing method, belonging to the field of petrochemical industry. Background Art

[0002] Crude isopentene is a byproduct of the production process of polymerization-grade isoprene. When the cracking C5 separation unit produces 1 ton of polymerization-grade isoprene, it can produce about 1.8 tons of crude isopentene as a byproduct. At present, crude isopentene is mainly used in gasoline, and less than 5% enters some fine chemical plants for secondary processing. When it is added to gasoline, it cannot be added too much because it is rich in olefins and affects the saturated vapor pressure of gasoline. Therefore, it will cause low utilization rate and poor economic benefits. In addition, fine chemical plants can only extract a small part of the crude isopentene to synthesize the raw materials of petroleum resin. Therefore, it also has problems such as low utilization rate and poor economic benefits. In recent years, with the gradual increase in the production of refining and chemical projects, how to increase the value of the C5 olefin components produced by chemical plants has become a very valuable research topic. Summary of the invention

[0003] In order to solve the above-mentioned problems in the prior art, the present invention provides a method for processing crude isopentene in a chemical industry, which has the technical characteristics of increasing the added value of crude isopentene and effectively improving economic benefits.

[0004] In order to achieve the above object, the present invention is implemented by the following technical solutions:

[0005] The present invention provides a method for treating crude isopentene in a chemical industry, characterized in that the method comprises the following steps:

[0006] Step 1) using cracked C5 introduced from the tank area as a raw material, and sending it into a double-ring polymerization reactor for dimerization reaction to polymerize cyclopentadiene in C5 into dicyclopentadiene; the double-ring polymerization reactor then enters a decarbonization tower through a pipeline, the upper end of the decarbonization tower is connected to a C4 refining tower through a pipeline, and the lower end of the decarbonization tower is connected to a pre-deweighting tower through a pipeline;

[0007] Step 2) obtaining isopentadiene and dicyclopentadiene products from the bottom of the pre-deweighting tower and sending them to a deweighting tower through a pipeline, preheating the C5 fraction of dimers extracted from the top of the pre-deweighting tower to 70° C., removing dicyclopentadiene and part of isopentadiene through an extraction feed water washing tower into which washing water is introduced, and then sending them to the upper part of an isoprene extraction distillation tower, introducing an acetonitrile solvent containing 5.0% (by weight) of water into the isoprene extraction distillation tower, discharging C5 alkanes, monoolefins and a small amount of isoprene with part of acetonitrile and water from the top of the isoprene extraction distillation tower, and sending them to a residual C5 water washing tower into which washing water is introduced, washing away the entrained acetonitrile through the residual C5 water washing tower, wherein the upper end of the residual C5 water washing tower is connected to a pipeline to send crude isopentene to a crude isopentene tank area and to a diene reactor as a raw material, and the lower end of the residual C5 water washing tower is connected to a pipeline to recover the solvent;

[0008] Step 3) firstly mix the coker naphtha with the crude isopentene obtained from the upper end of the residual carbon five water washing tower, and then enter the diolefin reactor (naphtha hydrogenation unit) together with the pressurized circulating hydrogen to saturate the diolefins in the coker naphtha to obtain the diolefin-saturated coker naphtha; the straight-run naphtha from the atmospheric and vacuum device enters the pre-fractionation tower (straight-run naphtha fractionation tower) for separation, and the top oil is removed through the pre-fractionation tower and the light naphtha removed is sent as the raw material of the ethylene cracking unit through the top pipeline of the pre-fractionation tower;

[0009] Step 4) mixing the obtained coking naphtha saturated with dienes with the straight-run naphtha obtained at the bottom of the pre-fractionator, and then sending the mixture to a hydrogenation reactor (naphtha hydrogenation unit) for desulfurization, denitrogenation, dechlorination and removal of metal impurities to obtain hydrogenated naphtha;

[0010] Step 5) The hydrogenated naphtha is passed into a fractionation tower for separation, wherein the refined heavy naphtha is obtained at the bottom of the fractionation tower and is used as a raw material for reforming and enters a subsequent reforming unit; the light naphtha is obtained at the top of the fractionation tower and is sent out as a raw material for an ethylene cracking unit.

[0011] Preferably, the crude isopentene obtained in step 2) is stored in a pressure storage tank, and the temperature is controlled to be ≮40°C.

[0012] Preferably, the flow rate of crude isopentene in step 3) is controlled to be no higher than 15% of the total feed flow rate.

[0013] Preferably, the coker naphtha feed is 31 t / h, the crude isopentene feed is 10 t / h, and the hydrogenation reactor feed is 342 t / h.

[0014] Beneficial effects: The crude isopentene can be introduced into the naphtha hydrogenation process to produce high-quality light naphtha, which can be used to produce high-value-added products after ethylene cracking, greatly increasing the added value of the crude isopentene and effectively improving the economic benefits of the entire plant. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 This is a crude isopentene production flow chart of the present invention.

[0016] Figure 2 This is a flow chart of the present invention for treating crude isopentene. DETAILED DESCRIPTION

[0017] The present invention will be further described below in conjunction with the accompanying drawings, but the present invention is not limited to the following embodiments.

[0018] like Figure 1-2 The figure shows a specific embodiment of a method for treating crude isopentene in a chemical industry. The embodiment is a method for treating crude isopentene in a chemical industry, and the method comprises the following steps:

[0019] Step 1) using cracked C5 introduced from the tank area as a raw material, sending it into a double-ring polymerization reactor for dimerization reaction to polymerize cyclopentadiene in C5 into dicyclopentadiene; the double-ring polymerization reactor then enters a decarbonization tower through a pipeline, the upper end of the decarbonization tower is connected to a C4 refining tower through a pipeline, the upper end of the C4 refining tower sends refined C4 to the tank area, the lower end of the C4 refining tower sends other components to water washing, and the lower end of the decarbonization tower is connected to a pre-deweighting tower through a pipeline;

[0020] Step 2) obtain isoprene and dicyclopentadiene products from the bottom of the pre-deweighting tower and send them to a deweighting tower through a pipeline, preheat the C5 fraction of dimers taken out from the top of the pre-deweighting tower to 70° C., pass through an extraction feed water washing tower with washing water to remove dicyclopentadiene and part of isoprene (the bottom of the extraction feed water washing tower is connected to a sewage treatment device through a pipeline), and then send it to the upper part of an isoprene extraction distillation tower, pass an acetonitrile solvent containing 5.0% (by weight) water into the isoprene extraction distillation tower, and remove the C5 alkanes, monoolefins and A small amount of isoprene entrained with part of acetonitrile and water is discharged from the top of the isoprene extraction and distillation tower (the bottom of the isoprene extraction and distillation tower is connected to the solvent removal and analysis tower through a pipeline), and sent to the residual carbon five water washing tower into which washing water is introduced, and the entrained acetonitrile is washed away by the residual carbon five water washing tower, wherein the upper end of the residual carbon five water washing tower is connected to the crude isopentene tank area through a pipeline and is sent to the diene reactor as a raw material, and the lower end of the residual carbon five water washing tower is connected to a pipeline to recover the solvent; the obtained crude isopentene is stored in a pressure storage tank, and the temperature is controlled to be ≮40°C;

[0021] Step 3) firstly mix the coking naphtha with the crude isopentene obtained from the upper end of the residual carbon five water washing tower (the flow rate of the crude isopentene is not higher than 15% of the total feed flow rate), and then enter the diolefin reactor (naphtha hydrogenation unit) together with the pressurized circulating hydrogen to saturate the diolefins in the coking naphtha to obtain the diolefin-saturated coking naphtha; the straight-run naphtha from the atmospheric and vacuum device enters the pre-fractionation tower (straight-run naphtha fractionation tower) for separation, and the top oil is removed through the pre-fractionation tower and the light naphtha removed is sent as the raw material of the ethylene cracking unit through the top pipeline of the pre-fractionation tower; a preferred parameter is that the coking naphtha feed is 31 t / h, the crude isopentene feed is 10 t / h, and the hydrogenation reactor feed is 342 t / h;

[0022] Step 4) mixing the obtained coking naphtha saturated with dienes with the straight-run naphtha obtained at the bottom of the pre-fractionator, and then sending the mixture to a hydrogenation reactor (naphtha hydrogenation unit) for desulfurization, denitrogenation, dechlorination and removal of metal impurities to obtain hydrogenated naphtha;

[0023] Step 5) The hydrogenated naphtha is passed into a fractionation tower for separation, wherein the refined heavy naphtha is obtained at the bottom of the fractionation tower and is used as a raw material for reforming and enters a subsequent reforming unit; the light naphtha is obtained at the top of the fractionation tower and is sent out as a raw material for an ethylene cracking unit.

[0024] The production of polymerization-grade isoprene in the technical case of this application is based on the cracking of C5 as raw material. First, a dimerization reaction is carried out to polymerize the cyclopentadiene in C5 into dicyclopentadiene. Dicyclopentadiene and part of isoprene are removed by distillation. Then, acetonitrile is used as a solvent and crude isoprene and dicyclopentadiene are removed by extractive distillation. High-purity isoprene is separated from the C5 components with very close boiling points, and crude isopentene is obtained. Crude isopentene is produced from the C5 water washing tower ( Figure 1 ), the properties of crude isopentene in this application are shown in the following tables (Table 1, Table 2).

[0025] Table 1 Composition and properties of crude isopentene

[0026] Analyze Project unit Composition 1 Isopentane %(mass fraction) 39.09 1,4-Pentadiene %(mass fraction) 3.03 2-Butyne %(mass fraction) 0.07 n-pentene %(mass fraction) 5.69 2-Methyl-1-butene %(mass fraction) 16.65 n-Pentane %(mass fraction) 24.27 Isoprene %(mass fraction) 1.65 trans-2-pentene %(mass fraction) 3.91 1-Penten-3-yne %(mass fraction) <0.01 1-Pentyne %(mass fraction) <0.01 Cis-2-Pentene %(mass fraction) 2.06 2-Methyl-2-butene %(mass fraction) 3.25 trans-1,3-pentadiene %(mass fraction) <0.01 Cyclopentadiene %(mass fraction) <0.01 Mass fraction of cyclopentane %(mass fraction) C6 and above components 1 %(mass fraction) C5 conjugated diene + dicyclopentadiene %(mass fraction) 1.67 C5 monoolefins %(mass fraction) Diolefin Index gI / 100g 0.7 Octane RON 90.6

[0027] Table 2 Comparison of properties of crude isopentene and coker naphtha

[0028]

[0029]

[0030] The present application can realize the blending of crude isopentene in a naphtha hydrogenation unit, wherein the crude isopentene has an olefin content of 40%, a diolefin value of 0.7 gI / 100g, and the nitrogen content and sulfur content meet the feed requirements. At present, conventional technology cannot realize the blending of crude isopentene in a naphtha hydrogenation unit. If the naphtha hydrogenation unit is directly used for blending, it is impossible to cope with the reaction exotherm and coking and ensure that the refined naphtha produced by the original unit is qualified.

[0031] like Figure 2 As shown, coker naphtha and straight-run naphtha are used as raw materials. A diolefin reactor is set up for the coker naphtha. The coker naphtha after diolefin saturation is mixed with the straight-run naphtha after decapping and enters the pre-hydrogenation reactor for desulfurization and denitrogenation. The straight-run naphtha adopts a process flow of first fractionation and then hydrogenation, and the product fractionation part adopts a process flow of first stripping and then fractionation. Process description: The straight-run naphtha from the atmospheric and vacuum device enters the straight-run naphtha fractionation tower for separation, and the light naphtha product is sent out as the raw material of the ethylene cracking unit. The straight-run heavy naphtha is obtained at the bottom of the fractionation tower. After mixing with the pressurized circulating hydrogen, it enters the hydrogenation reactor of the naphtha hydrogenation unit for refining. The hydrogenated heavy naphtha produced enters the reforming unit as the raw material for reforming. Coker naphtha and pressurized circulating hydrogen enter the diolefin reactor of the naphtha hydrogenation unit. First, the diolefins in the coker naphtha are saturated. Then, the reaction product and the above-mentioned straight-run heavy naphtha enter the hydrogenation reactor of the naphtha hydrogenation unit. Under the action of the catalyst, impurities such as sulfur, nitrogen, chlorine and metal are removed to obtain hydrogenated naphtha. The hydrogenated naphtha enters the fractionation tower for separation. The light naphtha is used as the raw material of the ethylene cracking unit, and the refined naphtha at the bottom of the tower is sent to the continuous reforming unit as the raw material. After reaction and fractionation, gas, light naphtha and heavy naphtha are separated respectively (see Table 3 for the main operating conditions).

[0032] Table 3 Main operating conditions

[0033]

[0034] After blending crude isopentene, the highest diene value in the monitored feed was 3.9gI / 100g, which was lower than the designed feed index ≤8gI / 100g. There was no significant change in the temperature rise of dienes and pre-hydrogenation main reaction. After hydrofining, the light naphtha production increased by 7t / h. Table 4 shows the light naphtha before blending, and Table 5 shows the composition changes after blending.

[0035] Table 4 Mass fraction composition of light naphtha before blending with crude isopentene

[0036] Cnum np ip O N A C.SUM C5 55.02 23.7 0 3.38 0 82.1 C6 0.86 16.72 0 0.08 0.18 17.84 T.Sum 55.88 40.42 0 3.46 0.18 99.94

[0037] Table 5 Mass fraction composition of light naphtha after blending with crude isopentene

[0038] Cnum np ip O N A C.SUM C5 45.57 49.03 0 1.07 0 92.67 C6 0.33 6.87 0 0.04 0.06 7.3 T.Sum 45.9 55.9 0 1.11 0.06 99.97

[0039] After the naphtha hydrogenation unit blended crude isopentene, the C5 component of light naphtha increased from 82.1% to 92.67%, indicating that crude isopentene was converted into light naphtha after reaction and separation, becoming a high-quality ethylene cracking raw material, as shown in Table 6.

[0040] Table 6 Product Distribution

[0041]

[0042]

[0043] The benefit calculation of the technical solution of this application:

[0044] Crude isopentene is used as a gasoline blending component and sold directly: 10t / h*5420 yuan / ton*24h=1.3008 million yuan / d.

[0045] Crude isopentene passes through naphtha hydrogenation unit: benefit increment 603180-593280=19580 yuan / d

[0046] The processing fee of crude isopentene through naphtha hydrogenation unit is about 51 yuan / ton, so the comprehensive benefit is: 603180-593280-10*24*51=7340 yuan / d.

[0047] Comprehensively comparing the technical solutions of this application, the annual economic benefit can reach 7340*365d=2.6791 million yuan.

[0048] Finally, it should be noted that the present invention is not limited to the above embodiments, and there are many variations. All variations that can be directly derived or associated with the content disclosed by ordinary technicians in this field should be considered as the protection scope of the present invention.

Claims

1. A method for treating crude isopentene in a chemical industry, Features The method comprises the following steps: Step 1) using cracked C5 introduced from the tank area as a raw material, and sending it into a double-ring polymerization reactor for dimerization reaction to polymerize cyclopentadiene in C5 into dicyclopentadiene; the double-ring polymerization reactor then enters a decarbonization tower through a pipeline, the upper end of the decarbonization tower is connected to a C4 refining tower through a pipeline, and the lower end of the decarbonization tower is connected to a pre-deweighting tower through a pipeline; Step 2) obtaining isopentadiene and dicyclopentadiene products from the bottom of the pre-deweighting tower and sending them to a deweighting tower through a pipeline, preheating the C5 fraction of dimers extracted from the top of the pre-deweighting tower to 70° C., removing dicyclopentadiene and part of isopentadiene through an extraction feed water washing tower into which washing water is introduced, and then sending them to the upper part of an isoprene extraction distillation tower, introducing an acetonitrile solvent containing 5.0% (by weight) of water into the isoprene extraction distillation tower, discharging C5 alkanes, monoolefins and a small amount of isoprene with part of acetonitrile and water from the top of the isoprene extraction distillation tower, and sending them to a residual C5 water washing tower into which washing water is introduced, washing away the entrained acetonitrile through the residual C5 water washing tower, wherein the upper end of the residual C5 water washing tower is connected to a pipeline to send crude isopentene to a crude isopentene tank area and to a diene reactor as a raw material, and the lower end of the residual C5 water washing tower is connected to a pipeline to recover the solvent; Step 3) firstly mix the coker naphtha with the crude isopentene obtained from the upper end of the residual carbon five water washing tower, and then enter the diolefin reactor (naphtha hydrogenation unit) together with the pressurized circulating hydrogen to saturate the diolefins in the coker naphtha to obtain the diolefin-saturated coker naphtha; the straight-run naphtha from the atmospheric and vacuum device enters the pre-fractionation tower (straight-run naphtha fractionation tower) for separation, and the top oil is removed through the pre-fractionation tower and the light naphtha removed is sent as the raw material of the ethylene cracking unit through the top pipeline of the pre-fractionation tower; Step 4) mixing the obtained coking naphtha saturated with dienes with the straight-run naphtha obtained at the bottom of the pre-fractionator, and then sending the mixture to a hydrogenation reactor (naphtha hydrogenation unit) for desulfurization, denitrogenation, dechlorination and removal of metal impurities to obtain hydrogenated naphtha; Step 5) The hydrogenated naphtha is passed into a fractionation tower for separation, wherein the refined heavy naphtha is obtained at the bottom of the fractionation tower and is used as a raw material for reforming and enters a subsequent reforming unit; the light naphtha is obtained at the top of the fractionation tower and is sent out as a raw material for an ethylene cracking unit.

2. A method for treating crude chemical isopentene according to claim 1, Features: The crude isopentene obtained in step 2) is stored in a pressure storage tank, and the temperature is controlled to be ≮40°C.

3. A method for treating crude isopentene in a chemical industry according to claim 1, Features: The flow rate of crude isopentene in step 3) is controlled to be no higher than 15% of the total feed flow rate.

4. A method for treating crude chemical isopentene according to claim 3, Features: The coker naphtha feed is 31t / h, the crude isopentene feed is 10t / h, and the hydrogenation reactor feed is 342t / h.

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