Process for the production of a blowing agent feedstock from the pentane fraction of a catalytic reforming unit

Abstract

The application discloses a device and method for producing foaming agent by pentane fraction of catalytic reforming device. The reforming oil raw material enters a pentane removal tower, and C4 / C5 fraction is obtained at the top of the tower, and a pentane fraction containing tower is extracted from the upper side line; the obtained pentane fraction containing tower enters a pentane hydrogenation reactor to perform hydrogenation reaction, hydrogenation products are mixed with low-temperature naphtha at the top of a reforming pre-hydrogenation unit separation tower, and then are returned to the upper part of the pentane removal tower; the obtained C4 / C5 fraction is subjected to gas-liquid separation to obtain liquid products, and the liquid products are divided into two streams, one of which is mixed with optional low-temperature naphtha at the top of the reforming pre-hydrogenation unit separation tower, and then enters a C4 / C5 fractionating tower, and the other stream is returned to the reflux inlet II of the pentane removal tower. The method greatly simplifies the hydrogenation process flow of the pentane fraction, and reduces the device investment and operation cost.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of hydrogenation technology, and relates to a method for producing foaming agent from pentane fraction of catalytic reforming device, in particular to a method for combining the hydrogenation treatment unit of pentane fraction of reforming device with the reforming device, which is particularly suitable for the reforming device requiring production of foaming agent raw material. BACKGROUND

[0002] The reformate can be directly used as a blending component of motor gasoline, and can also be extracted by aromatic extraction to produce benzene, toluene and xylene, while by-product hydrogen. The low molecular hydrocarbons which cannot be converted into aromatic hydrocarbons, mainly C5- fraction, have not been widely concerned. In China, cyclopentane is used as a foaming agent for polyurethane industry instead of freon and can completely replace imported products; cyclopentane is also an important basic chemical raw material, such as chlorinated cyclopentane, cyclopentadiene, etc. Isopentane can be used as a solvent for catalysts for synthesizing polyethylene, a foaming agent for expandable polystyrene, a foaming agent for polyurethane foam system, a solvent for deasphalting; isopentane is also an important basic chemical raw material, such as isopentyl alcohol, isoprene, etc. n-Pentane can be used as a desorption agent for molecular sieve dewaxing process, and after blending with isopentane in different proportions, it can meet the requirements of different foaming degrees and can completely replace imported products; the further development of the saturated hydrocarbons such as hydrocarbon aerosol, foaming agent, solvent oil, etc. is widely used in the cosmetics, perfume, rubber, plastic and oil industries.

[0003] With the increasing global refining capacity, the production of light naphtha also increases substantially, and how to reasonably use the light naphtha of reforming device becomes an important issue in industrial production. Since the light naphtha is rich in C5 alkanes, this part of raw material can be used to produce high-purity pentane oil, i.e. pentane foaming agent. Foaming agent is a substance that promotes the generation of foam to form a closed or linked pore structure material, also known as foaming agent or foaming agent. Traditional fluorochlorohydrocarbon foaming agents are gradually abandoned due to environmental pollution problems, and pentane foaming agent can meet the environmental protection requirements as a substitute for fluorochlorohydrocarbon due to its small greenhouse gas potential (GWP), low toxicity, safety and environmental protection, etc. From the physical and chemical properties of foaming agent, the reforming device is very suitable for producing high-purity pentane foaming agent. The sulfur, nitrogen, oxygen and other impurities in the naphtha are removed by the reforming pre-hydrogenation reactor, and after separation by the fractionation unit, high-quality pentane foaming agent can be obtained.

[0004] In recent years, China's oil refining industry has rapidly expanded its capacity through a combination of expansion and new construction. However, the market for fuel oil is becoming saturated, and the overcapacity problem is becoming increasingly prominent. In addition, the rapid development of new energy vehicles is expected to reduce demand for gasoline, and some enterprises are having difficulty in producing gasoline. Light naphtha used as a blending component for gasoline will reduce the octane number and increase the saturated vapor pressure of gasoline, which has a greater impact in summer. Against this background, many domestic refining and chemical enterprises have further optimized the use of light naphtha through process adjustment, adjustment of processing schemes, and the construction of new devices.

[0005] CN111362773A discloses a device for preparing pentane blowing agent from reforming overhead naphtha and a process thereof. The method connects a feed buffer tank with a de-isopentane column, and the top of the de-isopentane column is connected with the bottom of a common rectifying column. A baffle tower is arranged in the de-isopentane column, and the upper side line of the de-isopentane column is connected with an isopentane product tank, and the middle side line of the de-isopentane column is connected with a blowing agent tank. The bottom of the common rectifying column is connected with the top of the de-isopentane column through a common rectifying column feed pump. The present application omits the reaction section and the subsequent fractionation section, and has obvious energy-saving effect. In addition, the process uses a baffle rectification process technology to complete the operation that two fractionating columns can complete, thereby saving the investment of equipment. However, compared with the method of the present application, the raw material processed by the method is light naphtha obtained from a reforming pre-hydrogenation device, while the method of the present application processes light naphtha on the top of a de-pentane column of a reforming device, and the raw materials and properties are completely different.

[0006] CN104557392B discloses a method for producing pentane. Ether post carbon five is used as raw material, and hydrogenation and removal of residual olefins are performed to produce pentane product with qualified pentane index. The ether post carbon five and hydrogen are mixed and then subjected to hydrogenation reaction through a fixed bed catalyst bed, and the catalyst is a Ni / diatomite catalyst. The hydrogenation product is subjected to removal of residual unsaturated hydrocarbons through a strong acid cation exchange resin fixed bed at a temperature of 10-40℃. The raw material processed by the method is completely different from the method of the present application, and the catalyst used and the reaction mechanism also have great differences. In addition, a new independent hydrogenation device needs to be built, and the investment and operating cost are also relatively high. SUMMARY

[0007] In view of the deficiencies of the prior art, the present application provides a device and method for producing blowing agent from pentane fraction of a catalytic reforming device. By deeply coupling the pentane hydrogenation treatment device with the reforming device, not only can the indicators of the hydrogenated pentane oil fraction meet the requirements for producing blowing agent, but also the investment, energy consumption, operating cost, and land occupation are greatly reduced compared with the existing device, and the problem that the temperature of the material on the top of the de-pentane column does not meet the reaction requirements of the hydrogenation unit is solved.

[0008] According to a first aspect of the present application, the present application provides a device for producing a blowing agent raw material from a pentane fraction of a catalytic reforming device.

[0009] Specifically, the device for producing a blowing agent raw material from a pentane fraction of a catalytic reforming device comprises:

[0010] a de-pentanizer for fractionating a reformate product into a C4 / C5 fraction and a heavy fraction (i.e. a C6+ fraction); the de-pentanizer comprises a feed line for feeding a reformate raw material into the de-pentanizer, a bottom take-off for removing the heavy fraction, a side-draw for withdrawing a pentane-containing fraction from an upper portion of the de-pentanizer, and an overhead take-off for removing the overhead product C4 / C5 fraction;

[0011] a pentane hydrogenation reactor in which the pentane-containing fraction is subjected to a hydrogenation reaction in the presence of a hydrogenation catalyst; the pentane hydrogenation reactor is connected to the side-draw, and an outlet line of the pentane hydrogenation reactor is connected to a reflux inlet I of an upper portion of the de-pentanizer after being combined with the overhead naphtha line of the reforming pre-hydrogenation unit separation tower;

[0012] a gas-liquid separator in which the cooled de-pentanizer overhead product is separated into a gas and a liquid product; the liquid outlet of the gas-liquid separator is connected to a reflux inlet II of a C4 / C5 fractionation tower and a feed inlet of the C4 / C5 fractionation tower, respectively;

[0013] a C4 / C5 fractionation tower in which the liquid product from the gas-liquid separator is separated into a liquefied gas and a pentane oil; the C4 / C5 fractionation tower comprises a take-off for removing the liquefied gas, a bottom take-off for removing the pentane oil product, and an optional feed line for feeding part of the low-temperature naphtha from the top of the reforming pre-hydrogenation unit separation tower into the C4 / C5 fractionation tower;

[0014] wherein the opening positions of the reflux inlet I, the side-draw outlet, and the reflux inlet II are sequentially lowered.

[0015] Further, a valve is provided on the reforming device pre-hydrogenation low-temperature naphtha line for controlling the flow of the reforming device pre-hydrogenation low-temperature naphtha into the de-pentanizer.

[0016] Further, the device further comprises a reformate liquid-phase hydrogenation reactor, and the outlet of the reformate hydrogenation reactor is connected to the feed inlet of the de-pentanizer.

[0017] Further, the opening position of the reflux inlet I is 1-7 tray higher than the side-draw outlet, preferably 2-5 trays higher; and the opening position of the reflux inlet II is 1-6 trays lower than the side-draw outlet, preferably 2-4 trays lower.

[0018] In the present application, since the discharge temperature of the de-pentanizer overhead gas phase product cannot meet the hydrogenation reaction requirement, the pentane hydrogenation unit is arranged at a suitable position of the de-pentanizer side line to ensure that the temperature of the side line extracted pentane-containing material can directly meet the hydrogenation reaction condition requirement. Meanwhile, the side line hydrogenation unit is arranged in the upper part of the de-pentanizer, and the process flow of the lower part extraction and upper part return is adopted, which can effectively avoid the problem of repeated hydrogenation of the side line extracted pentane-containing material.

[0019] In the present application, since the de-pentanizer overhead material temperature cannot meet the hydrogenation reaction requirement, the temperature needs to be increased by 10-25℃ to meet the reaction requirement, therefore, the pentane hydrogenation unit is arranged at a suitable position of the de-pentanizer side line to ensure that the extracted material temperature can directly meet the hydrogenation reaction condition requirement. Preferably, the pentane hydrogenation reactor is arranged at the upper side line position of the de-pentanizer in the reforming device, generally at the 3rd-30th tray, preferably at the 5th-20th tray. The temperature of the de-pentanizer side line extracted material (containing hydrogen) can directly reach the required operating condition, and the pentane hydrogenation reactor introduced material directly enters the normal production stage without producing unqualified products.

[0020] According to the second aspect of the present application, the present application provides a method for producing a foaming agent raw material from the pentane fraction of a catalytic reforming device.

[0021] Specifically, the method for producing a foaming agent raw material comprises the following steps:

[0022] (1) The reformate raw material enters the de-pentanizer, and C4 / C5 fraction is obtained at the top, pentane-containing fraction is extracted from the upper side line, and C6+ fraction is obtained at the bottom;

[0023] (2) The pentane-containing fraction obtained in step (1) directly enters the pentane hydrogenation reactor, and hydrogen is added to the reactor to perform hydrogenation reaction in the presence of a hydrogenation catalyst;

[0024] (3) The product of the pentane hydrogenation reactor is mixed with low-temperature naphtha at the top of the reforming pre-hydrogenation unit separation tower, and then returns to the upper part of the de-pentanizer through reflux port I;

[0025] (4) The C4 / C5 fraction obtained in step (1) is cooled and then separated in a gas-liquid separator to obtain light hydrocarbon and liquid product;

[0026] (5) The liquid product obtained in step (4) is divided into two streams, one of which is mixed with optional low-temperature naphtha at the top of the reforming pre-hydrogenation unit separation tower, and then enters the C4 / C5 fractionating tower, and the other stream returns to the reflux port II of the de-pentanizer.

[0027] Further, the temperature of the pentane-containing fraction extracted from the side line in step (1) is generally 95-135℃, and preferably 105-130℃.

[0028] Further, in step (2), the hydrogenation reaction conditions include: the reaction pressure is generally 0.5 MPa to 6.0 MPa, preferably 0.8 MPa to 2.0 MPa. The reaction pressure is determined according to the pressure at the top of the depentanizer, and generally does not need to be adjusted, and can also be appropriately adjusted as needed. The reaction temperature is generally 80°C to 200°C, preferably 100°C to 160°C. The liquid phase volume space velocity is 1.0 h -1 ~15.0 h -1 , preferably 4.0 h -1 ~10.0 h -1 . The hydrogen (i.e. the additional introduced supplemental hydrogen) oil volume ratio is 0 to 20:1 (since the pentane fraction containing hydrogen dissolved is extracted from the side line of the depentanizer, the additional introduced hydrogen can be 0), preferably 3 to 8:1. In the present application, the hydrogen oil volume ratio can be significantly reduced compared with the conventional method.

[0029] In the present application, during the pentane hydrogenation reaction, the material is in a gas phase circulation mode. Since the temperature distribution of the depentanizer is gradually increased from the bottom to the top, and the hydrogenation reaction is an exothermic reaction, the temperature of the material after the reaction will be higher than the temperature of the feedstock. Therefore, to achieve the process flow of extracting the material from the lower part of the depentanizer and returning it to the upper part, the temperature of the material after the reaction must be reduced. By mixing a small part of the naphtha at the top of the reforming pre-hydrogenation unit fractionator entering the C4 / C5 fractionator with the hydrogenation reaction product to reduce the temperature of the material after the reaction, so as to meet the temperature requirement of returning to the upper part of the depentanizer, and has no adverse effect on the normal operation of the depentanizer. In addition, since the pentane-containing material extracted from the side line contains a small amount of carbon six or more aromatic hydrocarbon components, in order to avoid the loss of high-value aromatic hydrocarbons due to the saturation of aromatic hydrocarbons, it is preferred to load a high-selectivity noble metal or high-nickel hydrogenation catalyst in the pentane hydrogenation reactor, so that the aromatic content of the material after hydrogenation is basically not reduced.

[0030] The hydrogenation catalyst in step (2) can be a commercial hydrogenation refining catalyst, such as a hydrogenation refining catalyst with noble metal or reduced nickel as active component. Such catalysts have high hydrogenation selectivity and can selectively hydrogenate olefins at relatively low temperature, while having very weak hydrogenation performance for aromatic hydrocarbons. In the present application, a hydrogenation refining catalyst with intermediate noble metal as active component is preferably used, such as the FHDO-18 catalyst developed and produced by SINOPEC (Dalian) Petroleum Chemical Research Institute. The noble metal hydrogenation refining catalyst generally uses alumina as carrier and Pt and / or Pd as active component, with the content of active component in the catalyst being not less than 0.1% by weight, generally 0.1%-1.5% by weight. For the hydrogenation refining catalyst with reduced nickel as active component, generally alumina or modified alumina is used as carrier and nickel oxide is used as active component (15%-70% by weight of nickel oxide in the catalyst, preferably 25%-45% by weight). Before use, the catalyst is reduced and activated to convert nickel oxide into reduced state, so as to improve the hydrogenation activity of the catalyst. The active metals of the two kinds of catalysts are both distributed on the outer surface of the catalyst. For the pentane fraction of reformate, the use of the hydrogenation refining catalyst can make the bromine index of the pentane fraction of reformate less than 100 mgBr / 100 g, meeting the index requirement for the production of pentane blowing agent.

[0031] Further, in step (3), the temperature of the reflux stream obtained by mixing the pentane hydrogenation product with the low-temperature naphtha from the top of the fractionating column of the pre-hydrogenation unit of the reformer is generally 80-120°C, preferably 90-115°C. The mixing ratio of the low-temperature naphtha from the top of the fractionating column of the pre-hydrogenation unit of the reformer to the pentane hydrogenation product is generally 20-70 m%, preferably 30-60 m%.

[0032] Further, the pentane hydrogenation reactor can be operated in the top feeding mode, i.e. the reaction material enters the reactor from the upper part of the hydrogenation reactor for hydrogenation reaction. The refined oil is not cooled and separated, but mixed with a small amount of the low-temperature naphtha from the top of the fractionating column of the pre-hydrogenation unit of the reformer entering the C4 / C5 fractionating column, so as to reduce the temperature of the post-reaction material and meet the temperature requirement for returning to the upper part of the de-pentanizer, without adversely affecting the normal operation of the de-pentanizer. The pentane hydrogenation reactor can also be operated in the bottom feeding mode, i.e. the reaction material enters the reactor from the bottom of the hydrogenation reactor for hydrogenation reaction. The pentane hydrogenation reactor is operated in the gas phase reaction state, i.e. under the reaction conditions, most of the pentane fraction is in the gas phase state. The bottom of the pentane hydrogenation reactor is provided with a material conveying device, which conveys all the pentane reformate to the reflux inlet at the corresponding position of the de-pentanizer side line. The de-pentanizer is generally provided with a reboiler to provide heat source for the de-pentanizer. When the pentane fraction hydrogenation reactor is started, part or all of the overhead material of the de-pentanizer returns to the top of the de-pentanizer.

[0033] Further, the gas-liquid separator in step (4) adopts the conventional operating conditions in the art.

[0034] Further, in step (5), the mass ratio of the liquid product obtained in step (4) to the return de-pentanizing column reflux port II is generally 1:6-1:1, preferably 1:4-1:2.

[0035] Further, the proportion of the naphtha separated from the top of the reforming pre-hydrogenation unit separation column to the stream entering the C4 / C5 fractionating column through reflux port I is generally 10-60 m%, preferably 20-50 m%.

[0036] Further, the temperature of the low-temperature naphtha separated from the top of the reforming pre-hydrogenation unit separation column is generally 20-70℃, preferably 25-55℃.

[0037] Further, the de-pentanizing column in step (1) adopts the conventional operating conditions in the art. The operating conditions generally include: the top column temperature is 80~100℃, the bottom column temperature is 185~225℃, and the operating pressure is 0.8~1.0MPa.

[0038] The method for producing a foaming agent from the pentane fraction of the catalytic reforming device in the present application comprises the following contents: liquid phase hydrogenation treatment is performed on the reformate before entering the de-pentanizing column to remove most of the trace olefins therein. The hydrogenated reformate and the remaining hydrogen enter the de-pentanizing column for fractionation, and a hydrogenation reaction unit is additionally arranged in the upper part of the de-pentanizing column. The side stream of the de-pentanizing column (containing hydrogen) directly enters the hydrogenation reactor for reaction. The reaction effluent is mixed with part of the low-temperature naphtha from the top of the pre-hydrogenation unit fractionating column of the reforming device, and then returned to the de-pentanizing column through reflux port I above the side stream extraction point for re-fractionation. The top material of the de-pentanizing column is cooled and then enters the product separator. The gaseous components after separation are discharged from the device, and the liquid hydrogenation product enters the subsequent C4 / C5 fractionating column. The C5 fraction separated from the bottom can be directly used for producing a pentane foaming agent.

[0039] Compared with the prior art, the present application has the following beneficial effects:

[0040] 1. After the hydrotreating process of reformed oil, the bromine index of the separated pentane fraction remains high, generally reaching several thousand or even tens of thousands. For more demanding reforming units, the bromine index of the pentane fraction is even higher. If used as a raw material for producing foaming agents, further processing is necessary. Generally speaking, hydrotreating can refine the product to meet requirements, but the necessary reaction conditions must be met for the properties of the pentane-derived oil to meet the requirements for foaming agent raw materials. However, the temperature at the top of the depentane stripping tower in the reforming unit is significantly low, requiring the reactants to be raised by at least 10-25°C. By setting the pentane hydrotreating unit at a suitable location on the side stream of the depentane stripping tower, the temperature of the side stream extractor material can directly meet the requirements of the hydrotreating reaction, completely solving the problem of substandard pentane-derived oil properties caused by unsuitable reaction conditions. This method also has advantages such as short start-up time and no substandard products leaving the unit.

[0041] 2. In this invention, the added pentane hydrogenation unit is cleverly positioned at a suitable location on the side stream of the depentane tower, ensuring that the material temperature directly meets the reaction requirements. The process of extracting material from the bottom and returning it from the top avoids the problem of increased aromatic loss due to repeated hydrogenation of pentane-containing materials, and has no adverse impact on the normal operation of the depentane tower. The design of the pipeline and corresponding valves for the pentane hydrogenation product returning to the depentane tower is tailored to the specific characteristics of the device, namely, a suitable top pressure in the depentane tower but a relatively high temperature (excessive reaction temperature is detrimental to olefin saturation and easily leads to excessive aromatic saturation, affecting product quality). This is achieved by mixing the pentane hydrogenation product with a small amount of low-temperature naphtha to lower the temperature of the reflux material, allowing it to smoothly return from the top of the depentane tower.

[0042] 3. This invention, while ensuring system pressure balance and meeting the pressure requirements for the hydrogenation reaction, fully utilizes the surplus hydrogen from the upper part of the depentanizer as feedstock hydrogen. This hydrogen, along with the pentane feedstock extracted from the depentanizer side stream, enters the hydrogenation reactor from the top of the reactor, significantly simplifying the process and reducing investment costs. When the pentane hydrogenation unit starts up, the material temperature at the corresponding location on the depentanizer side stream is sufficient for the hydrogenation reaction. Therefore, the material extracted from the side stream is directly introduced into the pentane hydrogenation reactor, allowing the hydrogenation reactor and hydrogenation catalyst to quickly reach the optimal state required for the reaction. This avoids the problem of the hydrogenation reaction product properties failing to meet specifications during unit start-up or normal operation. This method provides greater flexibility to the process and will not affect the normal operation of subsequent foaming agent production units. Attached Figure Description

[0043] Figure 1 This is a schematic diagram of the process of the device of the present invention.

[0044] wherein the numerals correspond to: 10 - depentanizer, 11 - feed line, 12 - overhead take-off, 13 - bottoms take-off, 14 / 15 - reflux port, 16 - side draw, 20 - pentane oil hydrogenation reactor, 21 - side draw line, 22 - line, 23 - make-up hydrogen line, 30 - cooler, 40 - gas-liquid separator, 41 / 42 - line, 421 - valve, 50 - C4 / C5 fractionator, 51 - gas line, 52 - liquid line, 71 / 72 - line, 721 - valve, 60 - reformate hydrogenation reactor, 61 - line. DETAILED DESCRIPTION

[0045] The method of the present application will now be described in detail with reference to the accompanying drawings and specific examples.

[0046] In conjunction with Figure 1 the apparatus for producing a blowing agent raw material of the present application comprises:

[0047] a depentanizer 10 for fractionating a reformate raw material into a C4 / C5 fraction and a heavy (C6+) fraction; the depentanizer 10 includes a feed line 11 for feeding the reformate raw material to the depentanizer, a bottoms take-off 13 for taking off the heavy (C6+) fraction, a side draw 21 for taking off a pentane fraction from the upper portion of the depentanizer, and an overhead take-off 12 for taking off the C4 / C5 fraction as an overhead product;

[0048] a pentane hydrogenation reactor 20 in which the pentane fraction is hydrogenated in the presence of a hydrogenation catalyst; the pentane hydrogenation reactor 20 is connected to the side draw, and the product outlet line 22 of the pentane hydrogenation reactor is connected to the reflux port I 14 in the upper portion of the depentanizer after being combined with the overhead naphtha line 72 from the reforming pre-hydrogenation unit separation column;

[0049] a gas-liquid separator 40 in which the cooled overhead product from the depentanizer is separated into a gas and a liquid product; the liquid outlet of the gas-liquid separator is connected to the reflux port II 15 of the C4 / C5 fractionator and the feed inlet of the C4 / C5 fractionator 50 via lines 42 and 43, respectively;

[0050] a C4 / C5 fractionator 50 in which the liquid product from the gas-liquid separator is separated into a liquefied gas and a pentane oil, which are removed via lines 51 and 52, respectively; the C4 / C5 fractionator 50 includes a take-off 51 for removing the liquefied gas, a bottoms take-off 52 for removing the pentane oil product, and an optional line 71 for feeding a portion of the low-temperature naphtha from the overhead of the reforming pre-hydrogenation unit separation column to the C4 / C5 fractionator;

[0051] The positions of reflux port I 14, side stream outlet 16, and reflux port II 15 decrease sequentially. Preferably, reflux port I 14 is 1-7 trays higher than side stream outlet 16, more preferably 2-5 trays higher; reflux port II 15 is 1-6 trays lower than side stream outlet 16, more preferably 2-4 trays lower.

[0052] Furthermore, the apparatus also includes a reforming oil liquid phase hydrogenation reactor 60, the outlet of which is connected to the feed inlet of the depentanizer.

[0053] In this invention, since the outlet temperature of the gaseous product from the top of the depentanizer tower cannot meet the requirements for the hydrogenation reaction, the pentane hydrogenation unit needs to be positioned appropriately on the side stream of the depentanizer tower to ensure that the temperature of the pentane-containing material extracted from the side stream directly meets the requirements for the hydrogenation reaction. Simultaneously, by adding the side stream hydrogenation unit to the upper part of the depentanizer tower and adopting a process flow of bottom extraction and top return, the problem of repeated hydrogenation of the pentane-containing material extracted from the side stream can be effectively avoided.

[0054] In this invention, since the temperature of the material at the top of the depentane tower cannot meet the requirements of the hydrogenation reaction, it needs to be increased by 10-25°C to meet the reaction requirements. Therefore, the pentane hydrogenation unit is set at a suitable position on the side line of the depentane tower to ensure that the temperature of the extracted material can directly meet the requirements of the hydrogenation reaction. Preferably, the pentane hydrogenation reactor is set at the upper side line position of the depentane tower in the reforming unit, generally at the 3rd to 30th tray, preferably at the 5th to 20th tray. The temperature of the material (containing hydrogen) extracted from the side line of the depentane tower can directly reach the required operating conditions. After the material is introduced into the pentane hydrogenation reactor, it directly enters the normal production stage without the generation of unqualified products.

[0055] For reforming apparatus employing the method of the present invention, such as Figure 1 As shown: The reformed oil product enters the depentane tower 10 for fractionation via pipeline 11 (containing residual hydrogen from the reaction). The pentane fraction (containing hydrogen) in the side stream is extracted via side stream 21 and enters the pentane hydrogenation reactor 20 with optional supplementary hydrogen via supplementary hydrogen pipeline 23. The hydrogenation reaction product is mixed with a small amount of naphtha from the top of the reforming pre-hydrogenation unit separation tower flowing through pipeline 72, cooled, and then returned to the depentane tower 3 through the reflux port I14 at the top of the depentane tower for re-fractionation. The naphtha from the top of the reforming pre-hydrogenation unit separation tower and the reaction product and mixing amount of the pentane hydrogenation unit are controlled by the valve position. Reflux port II15 can effectively control the temperature of the return to the depentane tower 10. The refined pentane fraction is removed from the top of the tower by device 12, passes through cooler 30 and gas-liquid separator 40 to the downstream C4 / C5 fractionation tower 50, and the separated refined pentane oil is removed via pipeline 52 and can be directly used to produce pentane foaming agent. Once the normal production process begins, this flexible process avoids the problem of unqualified pentane products caused by substandard operating conditions at the top of the depentane tower.

[0056] In normal operation, the temperature of the pentane hydrogenation reactor reaction product 6 can be adjusted by flexibly adjusting the valve position of valve 721 to meet the requirements of returning to the upper part of the depentanizer, according to the required conditions of the reaction and the properties of the pentane raw material, without affecting the stable operation of the depentanizer 10. The feed conditions can directly meet the needs of the reaction, which solves the problem of unqualified pentane product entering the downstream foaming agent production device during the initial start-up and normal production, and avoids the impact on the normal production of the foaming agent device.

[0057] When the method of the present application is used for a reforming device using a clay refining process, the operation method is basically the same, and additional hydrogen needs to be supplied, but since the required hydrogen is very small, it can be introduced from a suitable position inside the reforming device. When the hydrogenation device is started, the reformate can be first treated by the clay refining device, then introduced into the depentanizer, and the side stream of the depentanizer is directly introduced into the hydrogenation reactor to remove trace amounts of olefins. The reaction product is mixed with a small amount of low-temperature reforming pre-hydrogenation column top naphtha, and then returned to the upper part of the depentanizer for fractionation again. The depentanizer top fraction passes through a cooler and a gas-liquid separator, enters the C4 / C5 fractionation column, and the bottom material is directly used to produce pentane foaming agent. The pentane hydrogenation reactor feed temperature directly meets the operating conditions required by the hydrogenation reaction, so that the hydrogenation reactor and the hydrogenation catalyst quickly reach the optimal state required by the reaction, and the problem of pentane hydrogenation product properties not meeting the specifications during device start-up is avoided.

[0058] The pentane reformate treated by the method of the present application can achieve the following properties: the refined oil bromine index is less than 100 mgBr / 100g, and other properties meet the requirements of foaming agent raw materials.

[0059] The present application has the advantages of simple process flow, easy operation, and lower investment. For existing reforming devices of oil refining enterprises, only a hydrogenation reactor and corresponding pipelines and valves need to be added to the side line of the depentanizer of the reforming device, without the need to build a separate hydrogenation device, which can greatly reduce investment and operating costs. The process flow of the method of the present application is simple, the operating conditions are relatively mild, and the method is easy to implement, and does not require additional hydrogen supply. If the existing process method is used, a hydrogenation device and supporting equipment need to be newly built, and the investment and operating costs are relatively high. The addition of a mixing pipeline and valve for mixing the low-temperature naphtha at the top of the reforming pre-hydrogenation column top with the reaction product can effectively reduce the temperature of the reaction product, so that it meets the requirements of returning to the depentanizer from the upper part of the pentane hydrogenation reactor feed position, avoiding the problem of repeated hydrogenation of the pentane fraction, and having no adverse effect on the normal operation of the depentanizer. In addition, the pentane hydrogenation reactor is filled with noble metal or high-nickel hydrogenation catalysts with high selectivity, and the active metals of the catalysts are distributed on the outer surface of the catalyst, so that the aromatic content of the hydrogenated material is basically not reduced.

[0060] The following embodiments will further illustrate the present invention.

[0061] The catalyst used in the experiment was an industrial hydrogenation catalyst, specifically the FHDO-18 hydrogenation catalyst developed and produced by Sinopec (Dalian) Petrochemical Research Institute Co., Ltd., whose physicochemical properties are shown in Table 1. Example

[0062] The reforming unit according to this application involves the reformed oil passing through a liquid-phase hydrogenation reactor and then entering a depentanizer along with the remaining hydrogen gas. The depentane feedstock 1 and hydrogen gas from the side stream of the depentanizer then enter the pentane hydrogenation reactor. The reaction conditions are: reaction pressure 0.95 MPa, volumetric hourly space velocity 7.0 h⁻¹. -1 The reactor inlet temperature is 108℃. The main operating conditions of the depentane tower are: top temperature 90℃, bottom temperature 207℃, and operating pressure 0.89MPa. The reflux inlet for the C5 fraction hydrogenation product is three trays higher than the reflux inlet for the C4 / C5 liquid phase product. The reflux ratio is 1:3. Using the method described in this invention for hydrogenation treatment ensures that the refined product directly meets the quality requirements of a foaming agent. The properties of the pentane feedstock and the product are listed in Table 2.

[0063] As shown in Table 2, this process technology can reduce the bromine index of the material after hydrogenation in the side stream of the depentane tower to below 100 mgBr / 100g, and no unqualified products are generated during the entire start-up process. Example

[0064] The process of refining reformate with clay is modified to the method described in this application. After refining in a clay tower, the reformate enters a depentanizer. The pentane feedstock 2 from the tower's side stream is mixed with supplementary hydrogen and then enters the pentane hydrogenation reactor. The reaction conditions are: reaction pressure 0.95 MPa, volume hourly space velocity 6.0 h⁻¹. -1 The reactor inlet temperature is 110℃, and the hydrogen-to-oil ratio is 6. The main operating conditions of the depentane tower are: top temperature 93℃, bottom temperature 211℃, and operating pressure 0.91MPa. The reflux inlet for the C5 fraction hydrogenation product is three trays higher than the reflux inlet for the C4 / C5 liquid phase product. The reflux ratio is 1:4. Using the method described in this invention for hydrogenation treatment ensures that the refined product directly meets the quality requirements of a foaming agent. The properties of the pentane feedstock and the product are listed in Table 3.

[0065] As shown in Table 3, this process technology can reduce the bromine index of the material after hydrogenation in the side stream of the depentane tower to below 100 mgBr / 100g, and no unqualified products are generated during the entire start-up process. Example

[0066] The reformer according to the present application. The reformate is sent to the liquid phase hydrogenation reactor and then to the de-pentanizer together with the hydrogen gas left in the reactor. The pentane feed 3 and hydrogen gas are sent to the pentane hydrogenation reactor. The reaction conditions are: reaction pressure 0.98 MPa, volume space velocity 6.7 h -1 The main operating conditions of the de-pentanizer are: top temperature 94℃, bottom temperature 215℃, operating pressure 0.94 MPa. The C5 fraction hydrogenation product reflux inlet is 4 plates higher than the C4 / C5 liquid phase product reflux inlet. The reflux ratio is 1:3. The hydrogenation treatment is carried out according to the method described in the present application, which can ensure that the refined product directly meets the quality requirements of the blowing agent. The properties of the pentane feedstock and the product are listed in Table 4.

[0067] As can be seen from Table 4, the bromine index of the material after hydrogenation of the de-pentanizer side line can be reduced to below 100 mgBr / 100g, and no unqualified product is generated during the entire start-up process.

[0068] Table 1 Physical and chemical property indexes of the catalyst

[0069] Catalyst FHDO-18 Metal composition Pt-Pd Physical properties Pore volume, mL / g ≮0.48 Specific surface area, m 2 / g]] ≮160 Compressive strength, N / cm ≮90 Shape Cylindrical bar

[0070] Table 2 Properties of the feedstock oil and test results of Example 1

[0071]

[0072] Table 3 Properties of the feedstock oil and test results of Example 2

[0073]

[0074] Table 4 Properties of the feedstock oil and test results of Example 3

[0075]

Claims

1. An apparatus for producing foaming agent feedstock from pentane fraction in a catalytic reforming unit, characterized in that, include: A depentanizer is used to fractionate reformed oil products into C4 / C5 fractions and C6+ heavy fractions; the depentanizer includes a feed line for feeding the reformed oil products into the depentanizer, a bottom removal device for removing the C6+ heavy fraction, a side outlet for extracting pentane-containing fractions from the top of the depentanizer, and a top removal device for removing the C4 / C5 fractions from the top of the tower; A pentane hydrogenation reactor in which pentane fraction and hydrogen are hydrogenated in the presence of a hydrogenation catalyst; the inlet of the pentane hydrogenation reactor is connected to the side outlet; the outlet pipeline of the pentane hydrogenation reactor merges with the naphtha pipeline at the top of the separation tower of the reforming pre-hydrogenation unit and is connected to the reflux port I at the top of the depentane tower. The tower top removal device is connected to the cooler and gas-liquid separator in sequence via pipelines; A gas-liquid separator in which the cooled C4 / C5 fraction is separated into gaseous and liquid products; the liquid outlet of the gas-liquid separator is connected to the reflux port II of the depentanizer and the feed port of the C4 / C5 fractionation tower, respectively. A C4 / C5 fractionation column, wherein the liquid product obtained from the gas-liquid separator is separated into liquefied petroleum gas (LPG) and pentane oil; the C4 / C5 fractionation column includes a removal device for removing LPG, a bottom removal device for removing pentane oil product, and a feed line for feeding a portion of the low-temperature naphtha from the top of the reforming pre-hydrogenation unit to the C4 / C5 fractionation column; Among them, the opening positions of reflux port I, side line extraction port and reflux port II are successively lower; A valve is installed on the naphtha feed line at the top of the reforming pre-hydrogenation unit separator to control the flow rate of naphtha from the top of the reforming pre-hydrogenation unit separator into the depentanizer.

2. The apparatus according to claim 1, characterized in that, It also includes a reforming product oil hydrogenation reactor, the outlet of which is connected to the feed inlet of the depentanizer.

3. The apparatus according to claim 1, characterized in that, The opening of reflux port I is 1-7 trays higher than the side stream outlet; the opening of reflux port II is 1-6 trays lower than the side stream outlet.

4. The apparatus according to claim 3, characterized in that, The opening of reflux port I is 2-5 trays higher than the side stream outlet; the opening of reflux port II is 2-4 trays lower than the side stream outlet.

5. A method for producing foaming agent feedstock from pentane fraction in a catalytic reforming unit, using the apparatus for producing foaming agent feedstock from pentane fraction in a catalytic reforming unit as described in any one of claims 1-4, characterized in that, Includes the following steps: (1) The reformed oil product enters the depentanizer, and C4 / C5 fraction is obtained at the top of the column. The pentane-containing fraction is drawn off from the side stream, and C6+ heavy fraction is obtained at the bottom of the column. (2) The pentane-containing fraction obtained in step (1) is directly fed into the pentane hydrogenation reactor and undergoes a hydrogenation reaction with hydrogen in the presence of a hydrogenation catalyst; (3) The pentane hydrogenation product is mixed with the low-temperature naphtha from the top of the separation tower of the reforming pre-hydrogenation unit and then returned to the top of the depentane tower through reflux port I; (4) The C4 / C5 fraction obtained in step (1) is cooled and then enters a gas-liquid separator for separation to obtain gaseous and liquid products; (5) The liquid product obtained in step (4) is divided into two streams. One stream is mixed with the low-temperature naphtha from the top of the reforming pre-hydrogenation unit separation tower and then enters the C4 / C5 fractionation tower. The other stream is returned to the reflux port II of the depentane tower.

6. The method according to claim 5, characterized in that, In step (1), the temperature at which the pentane-containing fraction is extracted via the side stream is 95-135℃.

7. The method according to claim 5, characterized in that, The conditions for the hydrogenation reaction include: a reaction pressure of 0.5 MPa to 6.0 MPa, a reaction temperature of 80°C to 200°C, and a liquid hourly space velocity of 1.0 h⁻¹. -1 ~15.0h -1 The hydrogen-to-oil volume ratio is 0~20:

1.

8. The method according to claim 7, characterized in that, The conditions for the hydrogenation reaction include: a reaction pressure of 0.8 MPa to 2.0 MPa, a reaction temperature of 100°C to 160°C, and a liquid hourly space velocity of 4.0 h⁻¹. -1 ~10.0 h -1 The hydrogen-to-oil volume ratio is 3 to 8:

1.

9. The method according to claim 5, characterized in that, In step (3), after the pentane hydrogenation product is mixed with the low-temperature naphtha from the top of the separation tower of the reforming pre-hydrogenation unit, the temperature of the reflux stream obtained is 80-120℃.

10. The method according to claim 9, characterized in that, Low-temperature naphtha from the top of the separation tower in the reforming pre-hydrogenation unit accounts for 20-70% of the pentane hydrogenation products.

11. The method according to claim 5, characterized in that, The mass ratio of the liquid product entering the C4 / C5 fractionation tower to the liquid product returning to the reflux port II of the depentanizer is 1:6-1:

1.

12. The method according to claim 5, characterized in that, The low-temperature naphtha from the top of the reforming pre-hydrogenation unit separation tower that enters the depentanizer via reflux port I accounts for 10-60% of the naphtha from the top of the reforming pre-hydrogenation unit separation tower that enters the C4 / C5 fractionation tower.

13. The method according to claim 5, characterized in that, The temperature of the low-temperature naphtha at the top of the separation tower in the reforming pre-hydrogenation unit is 20-70℃.

14. The method according to claim 5, characterized in that, The operating conditions of the depentane tower in step (1) include: top temperature of 80~100℃, bottom temperature of 185~225℃, and operating pressure of 0.8~1.0MPa.

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