Apparatus and process for producing blowing agent feedstock from the pentane fraction of a catalytic reforming unit

Abstract

The application discloses a method and device for producing foaming agent raw material from pentane fraction of catalytic reforming device. The method comprises the following steps: liquid phase hydrogenation treatment is performed on reforming oil; the hydrogenated reforming oil and residual hydrogen enter a de-pentanization tower for fractionation; a hydrogenation reaction unit is additionally arranged before a reflux tank at the top of the de-pentanization tower; the material at the top of the de-pentanization tower is heated by heat exchange and then enters the reaction unit for hydrogenation; the hydrogenation product enters a subsequent C4 / C5 fractionation tower; and the C5 fraction obtained at the bottom of the tower can be directly used as the raw material for producing pentane foaming agent. The method greatly simplifies the hydrogenation process flow of the pentane fraction, reduces the investment and operation cost of the device, and effectively solves the problem that the temperature of the material at the top of the de-pentanization tower cannot meet the hydrogenation reaction requirement during the initial start-up and normal production.

Description

Technical Field

[0001] This invention belongs to the field of hydrogenation technology and relates to an apparatus and method for producing foaming agent feedstock from pentane fraction in a catalytic reforming unit. Specifically, it involves embedding a pentane fraction processing unit into the reforming unit, which is particularly suitable for reforming units that require the production of foaming agent feedstock. Background Technology

[0002] Light naphtha from reforming units is a valuable petroleum resource. Its components are relatively light, primarily consisting of saturated alkanes, with C3 and C4 components accounting for approximately 40%–50%, C5 components for 50%–60%, and the remainder being trace amounts of C5+ components. Saturated C5 hydrocarbons such as n-pentane, isopentane, and cyclopentane have wide applications in industry. Isopentane can be used as a solvent for catalysts in the synthesis of polyethylene, a blowing agent for expandable polystyrene, a blowing agent for polyurethane foam systems, and a solvent for deasphalting. Isopentane is also an important basic chemical raw material, used in the production of isopentyl alcohol and isoprene. n-Pentane can be used as a desorbent in molecular sieve dewaxing processes; when blended with isopentane in different proportions, it can meet the requirements for different degrees of foaming and can completely replace imported products. Mixtures of n-pentane and isopentane can be used as catalysts for polyethylene. n-Pentane is also used as a chemical raw material to produce n-pentanol and n-pentanal. Currently, low-carbon, low-sulfur saturated hydrocarbons that are non-toxic, odorless, clean, and have certain volatility are receiving increasing attention. As a result, hydrocarbon aerosols, foaming agents, and solvent oils developed from these saturated hydrocarbons are widely used in industries such as cosmetics, fragrances, rubber, plastics, and oils.

[0003] With the increasing global refining capacity, the production of light naphtha has also increased significantly. How to rationally utilize light naphtha from reforming units has become an important issue in industrial production. Currently, light naphtha is often used as a gasoline blending component or a feedstock for aromatization units. However, because light naphtha is rich in C4-C6 alkanes, directly blending it into gasoline will lower the gasoline's octane number and increase its vapor pressure. Aromatization conversion of light naphtha requires new equipment, increasing investment costs. However, because light naphtha is rich in C5 alkanes, this feedstock can be used to produce high-purity pentane oil, i.e., pentane foaming agent. Foaming agents are substances that promote foam formation, thereby creating closed-cell or interconnected-cell structures; they are also called foaming agents or foaming agents. Traditional chlorofluorocarbon (CFC) foaming agents are gradually being abandoned due to environmental pollution problems. Pentane foaming agents, due to their low global warming potential (GWP), low toxicity, safety, and environmental friendliness, can serve as a substitute for CFCs, meeting various environmental protection requirements. From the perspective of the physicochemical properties of foaming agents, reforming units are very suitable for producing high-purity pentane foaming agents. The reforming pre-hydrogenation reactor removes impurities such as sulfur, nitrogen, and oxygen from naphtha, and after separation by the fractionation unit, high-quality pentane foaming agents can be obtained.

[0004] In recent years, China's refining industry has rapidly expanded its refining scale and increased its capacity through a combination of renovation, expansion, and new construction. This has led to a saturated fuel oil market and a growing overcapacity problem. Coupled with the rapid development of new energy vehicles, gasoline demand is expected to decline, causing some companies to experience difficulties in delivering gasoline. Furthermore, using light naphtha as a blending component lowers the octane number and increases the saturated vapor pressure of gasoline, a situation that is more pronounced in summer. Against this backdrop, many domestic refining and chemical companies have further optimized the use of light naphtha through process adjustments, processing scheme modifications, and the construction of new facilities. For example, a 2.6 million tons / year naphtha hydrotreating unit of a PetroChina company and a 300,000 tons / year naphtha hydrotreating unit of a Sinopec company use light naphtha to produce pentane foaming agents, achieving significant economic and social benefits.

[0005] CN111362773A discloses an apparatus and process for preparing pentane foaming agent from reformed naphtha. The method connects a feed buffer tank to a deisopentane tower, with the top of the deisopentane tower connected to the bottom of a common distillation tower. The deisopentane tower has a baffled section inside, with its upper side line connected to an isopentane product tank and its middle side line connected to a foaming agent tank. The bottom of the common distillation tower is connected to the top of the deisopentane tower via a common distillation tower feed pump. This invention omits the reaction section and subsequent fractionation section, resulting in significant energy savings. Furthermore, the process employs baffled distillation technology, completing operations that previously required two fractionation towers with a single tower, saving on equipment investment. However, compared to this invention, the feedstock processed by this method is light naphtha obtained from a reforming pre-hydrogenation unit, while the method of this invention processes light naphtha from the top of the depentane tower in a reforming unit; the feedstocks and their properties are completely different.

[0006] CN104557392B discloses a method for producing pentane. Using post-etherified C5 as a raw material, pentane with a qualified pentane bromide index is produced through hydrogenation and removal of residual olefins. The post-etherified C5 and hydrogen are mixed and hydrogenated through a fixed-bed catalyst bed. The catalyst is a Ni / diatomaceous earth catalyst. The hydrogenation product is then passed through a strongly acidic cation exchange resin fixed bed at a temperature of 10–40°C to remove residual unsaturated hydrocarbons. This method uses completely different raw materials than the method of this invention, and the catalyst and reaction mechanism are also significantly different. Furthermore, it requires the construction of a separate hydrogenation unit, resulting in relatively higher investment and operating costs. Summary of the Invention

[0007] To address the shortcomings of existing technologies, this invention provides an apparatus and method for producing foaming agent feedstock from pentane fraction in a catalytic reforming unit. By optimizing the combination of the pentane hydrogenation unit and the reforming unit, not only can the various indicators of the hydrogenated pentane product meet the requirements for foaming agent production, but the investment, energy consumption, and operating costs are also significantly reduced compared to existing equipment. Furthermore, it solves the problem of substandard product quality caused by unsatisfactory operating conditions during the initial start-up and production processes of the hydrogenation unit.

[0008] According to a first aspect of the present invention, the present invention provides an apparatus for producing foaming agent feedstock from pentane fraction of a catalytic reforming unit.

[0009] Specifically, an apparatus for producing foaming agent feedstock from pentane fraction in a catalytic reforming unit is characterized in that the apparatus comprises:

[0010] A depentanizer is used to fractionate reformed oil products into C4 / C5 and C6 fractions. + (i.e., C6 and above) fraction; the depentane tower includes a feed line for feeding the reforming product hydrogenation product into the depentane tower, a bottom removal device for removing the C6+ fraction, and a top removal device for removing the top product pentane fraction.

[0011] A pentane hydrogenation reactor in which pentane fraction is contacted with hydrogen to carry out a hydrogenation reaction; the hydrogenation reactor includes a hydrogenation catalyst bed; the inlet of the hydrogenation reactor is connected to a top removal device via a first heat exchanger; the outlet of the hydrogenation reactor is connected to a gas-liquid separator via a pipeline after passing through the first heat exchanger and an air cooler.

[0012] The first heat exchanger, in which the pentane fraction exchanges heat with the effluent from the hydrogenation reactor;

[0013] A gas-liquid separator separates the cooled hydrogenation reaction effluent into gaseous and liquid products; the liquid outlet of the gas-liquid separator is connected to the liquid reflux inlet at the top of the depentanizer and the feed inlet of the C4 / C5 fractionation tower, respectively.

[0014] Furthermore, the depentanizer tower is also equipped with a top gas reflux port located above the liquid phase reflux inlet. The outlet of the pentane hydrogenation reactor is connected to the top gas reflux port via a pipeline after passing through the first heat exchanger. Furthermore, a valve is installed on the pipeline to control the flow rate of the top gas reflux.

[0015] Furthermore, the apparatus also includes a C4 / C5 fractionation tower, in which the C4 / C5 fraction obtained from the gas-liquid separator is fractionated into C4 and C5 fractions.

[0016] Furthermore, the apparatus also includes a reforming oil hydrogenation reactor for hydrogenating the reforming oil fraction; the outlet of the reforming oil hydrogenation reactor is connected to the feed inlet of the depentanizer.

[0017] Furthermore, after the outlet of the pentane hydrogenation reactor passes through the first heat exchanger, a valve is installed on the connecting pipeline to the air cooler to control the flow rate of the material entering the gas-liquid separator through the air cooler.

[0018] According to a second aspect of the present invention, the present invention provides a method for producing foaming agent feedstock from pentane fraction in a catalytic reforming unit.

[0019] The method for producing foaming agent feedstock from pentane fraction in the catalytic reforming unit includes the following steps:

[0020] (1) The reformed oil products enter the depentanizer, where pentane fraction is obtained at the top and C6 fraction is obtained at the bottom. + distillate;

[0021] (2) Provide a pentane hydrogenation reactor; the pentane fraction obtained in step (1) is mixed with optional supplemental hydrogen, and after exchanging heat with the pentane fraction hydrogenation product in the first heat exchanger, it enters the pentane fraction hydrogenation reactor and passes through the hydrogenation catalyst bed under hydrogenation conditions.

[0022] (3) The hydrogenation product of the pentane fraction after cooling by the first heat exchanger is divided into two streams, one of which returns to the upper tray of the depentane tower through the gas phase reflux port.

[0023] (4) The other route of the hydrogenated product of the pentane fraction after cooling in the first heat exchanger is further cooled and then enters the gas-liquid separator to obtain gas phase product and C4 / C5 liquid phase product;

[0024] (5) The C4 / C5 liquid product obtained in step (4) is divided into two streams. One stream enters the downstream C4 / C5 fractionation tower, and the other stream is returned to the upper part of the depentane tower as liquid reflux through the liquid reflux port.

[0025] Furthermore, the reformed oil product mentioned in step (1) can be a hydrogenated product obtained by hydrogenating the reformed oil fraction (containing unreacted hydrogen or dissolved hydrogen), or it can be a product obtained by refining the reformed oil fraction with clay.

[0026] Furthermore, the position (gas phase reflux port) of the pentane fraction hydrogenation product returned to the depentane tower in step (3) is higher than the position (liquid phase reflux port) of the C4 / C5 liquid phase product returned to the depentane tower in step (4). Preferably, the position of the pentane fraction hydrogenation product returned to the depentane tower is 1-5 trays higher than the position of the C4 / C5 liquid phase product returned to the depentane tower. Setting the position of the pentane fraction hydrogenation product returned to the depentane tower higher than the position of the C4 / C5 liquid phase product returned to the depentane tower in step (4) allows a portion of the pentane fraction hydrogenation product passing through the first heat exchanger to re-enter the depentane tower and be further heated in the depentane tower. After being removed through the top of the tower, it is equivalent to increasing the inlet feed temperature of the pentane hydrogenation reactor, which helps to obtain the minimum temperature of the hydrogenation reaction as soon as possible in the initial stage of operation. After normal operation, the reflux flow rate of the pentane fraction hydrogenation product can be appropriately reduced by adjusting the valve opening.

[0027] Furthermore, the depentane degasser in step (1) operates under conventional conditions in the art. These conditions generally include: a top temperature of 80-120°C, a bottom temperature of 180-225°C, and an operating pressure of 0.8-1.2 MPa.

[0028] Furthermore, the hydrogenation conditions described in step (2) include: a reaction pressure generally of 0.5 MPa to 6.0 MPa, preferably 0.8 MPa to 2.0 MPa. The reaction pressure is usually determined based on the pressure at the top of the depentanizer and generally does not need to be adjusted, but can be adjusted appropriately as needed. The reaction temperature is generally 80℃ to 200℃, preferably 100℃ to 160℃. The liquid hourly space velocity is 1.0 h⁻¹. -1 ~15. 0h -1 Preferably 4.0 h -1 ~10.0 h -1 The hydrogen-to-oil volume ratio is 0~20:1 (since the depentanizer overhead material contains dissolved hydrogen, the additional hydrogen introduced can be 0), preferably 3~8:1. In this invention, the hydrogen-to-oil volume ratio can be significantly reduced compared to existing conventional methods.

[0029] Furthermore, the hydrorefining catalyst mentioned in step (2) can be a conventional hydrorefining catalyst or a hydrotreating catalyst in the art. The hydrorefining catalyst can be a commercial hydrorefining catalyst, such as a hydrorefining catalyst with noble metals or reduced nickel as the active component. Such catalysts have high hydrogenation activity and can carry out hydrogenation reactions at relatively low temperatures. Preferably, a hydrorefining catalyst with noble metals as the active component is used, such as the FHDA-10 catalyst developed and produced by Sinopec (Dalian) Petrochemical Research Institute Co., Ltd. Noble metal hydrorefining catalysts generally use alumina as a support and Pt and / or Pd as the active component. The content of the active component in the catalyst, by weight, is not less than 0.1%, generally 0.1% to 1.5%. For hydrorefining catalysts using reduced nickel as the active component, alumina or modified alumina is generally used as the support, and nickel oxide is used as the active component (accounting for 15%–70% of the catalyst weight, preferably 25%–45%). Before use, the catalyst is reduced and activated to convert the nickel oxide into a reduced state, thereby improving the catalyst's hydrorefining activity. For reformed pentane fraction feedstock, using this hydrorefining catalyst can reduce the bromine index of the reformed pentane fraction to less than 100 mgBr / 100g, meeting the requirements for producing foaming agent feedstock.

[0030] Furthermore, the volume ratio of the C5 fraction hydrogenated product returned to the top of the depentane tower in step (3) to the C5 fraction hydrogenated product entering the gas-liquid separator in step (4) is generally 1:4-1:1.

[0031] Furthermore, in step (4), the material used as liquid phase reflux in the C4 / C5 liquid phase product accounts for 10-50% of the total mass fraction of the C4 / C5 liquid phase product.

[0032] In this invention, a preferred configuration is a pipeline connecting the outlet of the pentane hydrogenation reactor back to the upper gas reflux port of the depentane tower. When the pentane hydrogenation reactor starts up, the material at the outlet of the pentane hydrogenation reactor is first returned entirely to the depentane tower for heat exchange and temperature increase. The material adopts a gas-phase total reflux method. After 5 minutes to 24 hours, preferably 1 to 10 hours, when the temperature of the material (containing hydrogen) at the top of the depentane tower reaches the operating conditions required for pentane hydrogenation and the temperature of the hydrogenation product is significantly increased, the valve for returning the pentane hydrogenation product to the depentane tower is gradually partially or completely closed. The pentane refined oil gradually enters the downstream cooler and gas-liquid separator, and the pentane hydrogenation unit enters the normal production stage.

[0033] In this invention, the pentane hydrogenation reactor is located between the top outlet of the depentanizer and the cooler. The material (containing hydrogen) discharged from the top of the depentanizer passes through a heat exchanger and enters the hydrogenation reactor. The pentane hydrogenation reactor adopts a top-feed operation, meaning the reactants enter the reactor from the top for hydrogenation. The refined oil, after cooling and separation, enters the C4 / C5 separation unit, and the C5 fraction can be directly used to produce foaming agent raw materials. The pentane hydrogenation reactor can also adopt a bottom-flow operation, meaning the reactants enter the reactor from the bottom for hydrogenation. The pentane hydrogenation reactor operates in a gas-phase reaction state, meaning that under the reaction conditions, the vast majority of the pentane fraction is in the gas phase. A material conveying device is installed at the bottom of the pentane hydrogenation reactor to partially or completely transport the pentane-generated oil to the corresponding inlet at the top of the depentanizer. The depentanizer typically has a bottom reboiler to provide a heat source for the depentanizer. When the pentane fraction hydrogenation reactor is started, part or all of the material at the top of the depentane column is returned to the top of the depentane column.

[0034] The pentane fraction described in this invention is the top fraction of the oil-de-pentane column generated in the reforming unit.

[0035] In this invention, to ensure that the feed temperature of the C5 fraction hydrogenation reactor is increased by reflux of the C5 fraction hydrogenation product through the return tower, without affecting the fractionation accuracy of the original depentanizer, the operating pressure of the depentanizer should be appropriately increased. Preferably, the operating pressure of the depentanizer can be increased by 0.1-1.0 MPa; most preferably, the operating pressure of the depentanizer can be increased by 0.2-0.5 MPa.

[0036] Compared with the prior art, the present invention has the following beneficial effects:

[0037] 1. Although the reformed product oil undergoes hydrogenation before entering the depentanizer, the bromine index of the separated pentane fraction remains high, typically 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, hydrogenation can refine the product to meet requirements, but the necessary reaction conditions must be met for the pentane product oil to meet the requirements for foaming agent raw materials. However, the reaction temperature at the top of the depentanizer in the reforming unit is significantly low, requiring the reactants to be heated by at least 10-25°C. By installing pipelines and corresponding valves to return the pentane product oil to the depentanizer, the problem of substandard pentane product oil properties caused by unsuitable reaction conditions is completely solved. This method also has advantages such as short start-up time and no substandard products leaving the unit. This invention cleverly employs the design of pipelines and corresponding valves for returning pentane-derived oil to the depentanizer. Considering the specific characteristics of the device—namely, a suitable top pressure in the depentanizer but a relatively low temperature—the return of part or all of the pentane-derived oil vapor phase material to the depentanizer ensures the material receives sufficient heat, meeting the reaction conditions and resolving the issue of substandard pentane refined oil properties. This invention is ingeniously conceived, with a simple process flow, easy implementation, low maintenance costs, and effectively avoids product quality defects.

[0038] 2. This invention, while ensuring system pressure balance and meeting the pressure requirements for the hydrogenation reaction, fully utilizes the surplus hydrogen gas from the top of the depentane tower as feedstock. Compared to having pentane feedstock enter the hydrogenation reactor from the top, this significantly simplifies the process and reduces investment costs. Furthermore, during startup of the hydrogenation unit, when the tower top temperature is too low to meet the hydrogenation reaction requirements, all the pentane hydrogenation reactor outlet material is first introduced into the depentane tower. This raises the temperature of the pentane fraction at the top of the tower to the operating conditions required for the hydrogenation reaction, allowing the hydrogenation reactor and catalyst to quickly reach the optimal state for the reaction. This prevents the hydrogenation reaction product properties from failing to meet specifications during startup. This method provides greater flexibility to the process and will not affect the normal operation of subsequent foaming agent production units. Attached Figure Description

[0039] Figure 1 This is a schematic diagram of a specific process of the method of the present invention.

[0040] In the diagram, the numbers correspond to: 10-Depentane tower, 11-Reformed oil hydrogenation product feed line, 12-Top removal device, 13-Bottom removal device, 14-Supplemental hydrogen line, 15-Liquid reflux port, 16-Gas reflux port, 20-First heat exchanger, 30-Pentane hydrogenation reactor, 31-Line, 311 / 312-Valve, 60-Air cooler, 40-Gas-liquid separator, 41 / 42 / 43-Line, 50-Reformed oil hydrogenation reactor, 51-Line. Detailed Implementation

[0041] The method of the present invention will now be described in detail with reference to the accompanying drawings and specific embodiments.

[0042] like Figure 1 As shown, the apparatus for producing foaming agent feedstock from pentane fraction provided by the present invention includes: a depentanizer 10, which is used to fractionate reformate oil hydrogenation product into pentane fraction and C6+ fraction; the depentanizer 10 includes a feed line 11 for feeding reformate oil hydrogenation product oil into the depentanizer 10, a bottom removal device 13 for removing C6+ fraction, and a top removal device 12 for removing top product pentane fraction;

[0043] The pentane hydrogenation reactor 30 is a reactor in which pentane fraction is contacted with hydrogen gas for hydrogenation reaction. The pentane hydrogenation reactor 30 includes a hydrogenation catalyst bed. The inlet of the pentane hydrogenation reactor is connected to the top removal device phase (i.e., the top gas phase pipeline) 12 via a first heat exchanger 20. The outlet of the hydrogenation reactor is connected to the gas-liquid separator 40 via a pipeline after passing through the first heat exchanger 20 and an air cooler 60. A valve 312 is installed on the pipeline.

[0044] First heat exchanger 20, in which pentane fraction, optional supplemental hydrogen and effluent from pentane hydrogenation reactor 30 exchange heat;

[0045] The gas-liquid separator 40 separates the cooled hydrogenation reaction effluent into gas and C4 / C5 liquid products; the liquid outlet of the gas-liquid separator 40 is connected to the liquid reflux inlet 17 at the top of the depentanizer 10 and the feed inlet of the C4 / C5 fractionation tower, respectively.

[0046] Preferably, the depentane tower 10 is further provided with a top gas reflux port 16 at a position higher than the liquid phase reflux inlet 15, and the outlet of the pentane hydrogenation reactor is connected to the top gas reflux port 16 via a pipeline 31 after passing through the first heat exchanger 20. A valve 311 is provided on the pipeline for controlling the flow rate of the gas reflux.

[0047] The apparatus also includes a C4 / C5 fractionation tower (not shown in the figure), in which the C4 / C5 liquid phase fraction is fractionated into C4 and C5 fractions.

[0048] Furthermore, the apparatus also includes a reformate oil hydrotreating reactor 50, in which the reformate oil fraction undergoes a hydrorefining reaction with hydrogen; the outlet of the reformate oil hydrotreating reactor 50 is connected to the feed inlet of the depentanizer.

[0049] Combination Figure 1 The method for producing foaming agent raw materials from pentane fraction of the present invention includes the following:

[0050] The pentane hydrogenation unit starts up. Reformate oil enters the liquid-phase hydrogenation reactor 50 via pipeline 51 and a heat exchanger. Hydrogenation products (including residual hydrogen) enter the depentanizer 10 via pipeline 11 for fractionation. The pentane fraction (containing hydrogen) at the top of the tower exits through unit 12 and the first heat exchanger 20, and enters the pentane hydrogenation reactor 30. Initially, valve 312 is closed, and valve 311 is slowly opened to return all pentane oil to the depentanizer 10 for reheating. The reheated material reaches the required operating conditions for the reaction. The pentane product re-enters the pentane hydrogenation reactor 10 via the top pipeline of the depentane tower for reaction. Simultaneously, the heat generated by the hydrogenation reaction serves as heat exchanger for the pentane feed fraction. At this point, valve 312 is slowly opened, and valve 311 is gradually partially or completely closed. The qualified pentane product, after being cooled by cooler 60, enters gas-liquid separator 40. The gaseous product, light hydrocarbons, is discharged from the unit via the top pipeline 41 of the gas-liquid separator. The liquid product enters the subsequent C4 / C5 fractionation tower via pipeline 42, and the bottom pentane fraction is directly used as raw material for producing foaming agents. The pentane hydrogenation unit then enters the normal production process flow. This flexible process flow avoids the problem of unqualified pentane products caused by substandard operating conditions during the initial start-up or production process.

[0051] During normal operation, the valve positions of valves 311 and 312 can be flexibly adjusted according to the reaction conditions and the changes in the properties of the pentane feedstock to ensure that the pentane feed conditions meet the reaction requirements. At the same time, this solves the problem of unqualified pentane products entering the downstream foaming agent production unit during the initial start-up and normal production process, thus avoiding the impact on the normal production of the foaming agent unit.

[0052] When using the method of this invention in a reforming unit employing the clay refining process, the operation is basically the same. Additional hydrogen needs to be supplied, but since the required amount is minimal, it can be introduced from a suitable location within the reforming unit. When starting the hydrogenation unit, the reforming product oil can first be processed through the clay refining unit and then introduced into the depentanizer. The top material from the depentanizer is then introduced into the hydrogenation reactor. All the pentane hydrogenation reactor outlet material is first introduced into the depentanizer for heat exchange, raising the temperature of the pentane fraction at the top of the tower to the operating conditions required for the hydrogenation reaction. This allows the hydrogenation reactor and hydrogenation catalyst to quickly reach the optimal state required for the reaction, preventing the pentane hydrogenation product properties from failing to meet specifications during unit startup.

[0053] The pentane-derived oil processed by the method of this invention can achieve the following properties: the bromine index of the refined oil is less than 100 mgBr / 100g, and other properties meet the requirements for use as a raw material for foaming agents.

[0054] The advantages of this invention are: simple process flow, easy operation, and low investment. For existing reforming units in oil refineries, only a hydrotreating reactor and corresponding pipelines and valves need to be added between the top of the depentane tower and the cooler in the reforming unit. It eliminates the need to build a separate hydrogenation unit, significantly reducing investment and operating costs. The method of this invention has a simple process flow, relatively mild operating conditions, strong feasibility, and requires no additional hydrogen supply. If existing processes are used, a new hydrogenation unit and supporting equipment are required, resulting in higher investment and operating costs. Simultaneously, by adding a return circulation pipeline from the bottom of the pentane hydrogenation reactor to the depentane tower, during the initial start-up and normal production process, the valve positions of valves 311 and 312 can be flexibly adjusted according to the reaction conditions and changes in the properties of the pentane feedstock to ensure that the pentane feed conditions meet the reaction requirements. This also prevents substandard pentane products from entering the downstream foaming agent production unit during the initial start-up and normal production process, avoiding any impact on the normal production of the foaming agent unit.

[0055] The following embodiments will further illustrate the present invention.

[0056] The catalyst used in the experiment was an industrial hydrogenation catalyst, specifically the FHDA-10 hydrogenation catalyst developed and produced by Sinopec (Dalian) Petrochemical Research Institute Co., Ltd., whose physicochemical properties are shown in Table 1. Example 1

[0057] use Figure 1 The apparatus is described above. After passing through a liquid-phase hydrogenation reactor, the reformed oil, along with the remaining hydrogen from the reaction, enters a depentanizer. The top of the depentanizer yields pentane feedstock 1 and hydrogen, which then enters the pentane hydrogenation reactor. Using the method described in this invention for hydrogenation, the pentane feedstock is first introduced into the depentanizer for heat exchange during startup. Once the top material of the depentanizer meets the reaction operating conditions, it is then introduced into the pentane hydrogenation reactor. After 3 hours, the process switches to normal operation (pentane feedstock enters the pentane hydrogenation reactor, and the pentane feedstock may partially or not return to the depentanizer). The main operating conditions of the depentanizer are: top temperature 106℃, bottom temperature 215℃, and operating pressure 1.1 MPa. 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. The properties of the pentane feedstock and the product are listed in Table 2.

[0058] As shown in Table 2, this process technology can reduce the bromine index of the depentane tower top material to below 100 mgBr / 100 g, and the product quality remains stable throughout the entire start-up process. Example 2

[0059] 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 at the top of the depentanizer is mixed with supplementary hydrogen and then enters the pentane hydrogenation reactor. The hydrogenation unit is started using the method described in this invention. During start-up, the pentane feedstock is first introduced into the depentanizer for heating. Once the top material of the depentanizer meets the reaction operating conditions, it is then introduced into the pentane hydrogenation reactor. After 5 hours, the process switches to normal operation (pentane feedstock enters the pentane hydrogenation reactor, and the pentane feedstock may partially or not return to the depentanizer). The main operating conditions of the depentanizer are: top temperature 112°C, bottom temperature 218°C, and operating pressure 1.15 MPa. The reflux inlet for the C5 fraction hydrogenation product is four trays higher than the reflux inlet for the C4 / C5 liquid phase product. The reflux ratio is 1:4. The properties of the pentane feedstock and product are listed in Table 3.

[0060] As shown in Table 3, this process technology can reduce the bromine index of reformed oil to below 100 mgBr / 100g, and the product quality remains stable throughout the entire start-up process. Example 3

[0061] use Figure 1 The apparatus is described above. After passing through a liquid-phase hydrogenation reactor, the reformed oil, along with the remaining hydrogen, enters a depentanizer. The top of the depentanizer yields pentane feedstock 3 and hydrogen, which then enters the pentane hydrogenation reactor. Using the method described in this invention for hydrogenation, the pentane feedstock is first introduced into the depentanizer for heat exchange during startup. Once the top material of the depentanizer meets the reaction operating conditions, it is then introduced into the pentane hydrogenation reactor. After 4 hours, the process switches to normal operation (pentane feedstock enters the pentane hydrogenation reactor, and the pentane feedstock may partially or not return to the depentanizer). The main operating conditions of the depentanizer are: top temperature 109°C, bottom temperature 221°C, and operating pressure 1.22 MPa. 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. The properties of the pentane feedstock and the product are listed in Table 4.

[0062] As shown in Table 4, this process technology can reduce the bromine index of the depentane tower top material to below 100 mgBr / 100 g, and the product quality remains stable throughout the entire start-up process.

[0063] Table 1 Physicochemical properties of catalysts

[0064]

[0065] Table 2 Properties and test results of feedstock oil in Example 1

[0066]

[0067] Table 3 Properties and test results of feedstock oil in Example 2

[0068]

[0069] Table 4. Properties and test results of the feedstock oil in Example 3

[0070]

Claims

1. An apparatus for producing foaming agent feedstock from pentane fraction in a catalytic reforming unit, characterized in that, The device includes: A depentanizer is used to fractionate reformed oil products into C4 / C5 fractions and C6+ fractions; the depentanizer includes a feed line for feeding the hydrogenated product of the reformed oil into the depentanizer, a bottom removal device for removing the C6+ fraction, and a top removal device for removing the top product C4 / C5 fraction. A pentane hydrogenation reactor in which C4 / C5 fractions are contacted with hydrogen to carry out a hydrogenation reaction; the hydrogenation reactor includes a hydrogenation catalyst bed; the inlet of the pentane hydrogenation reactor is connected to a top removal device via a first heat exchanger; the outlet of the pentane hydrogenation reactor is connected to a gas-liquid separator via a pipeline after passing through the first heat exchanger and an air cooler. The first heat exchanger is in which the C4 / C5 fraction exchanges heat with the C4 / C5 fraction hydrogenation product; A gas-liquid separator separates the cooled C4 / C5 fraction hydrogenation product into a gaseous product and a liquid product; the liquid outlet of the gas-liquid separator is connected to the liquid reflux inlet at the top of the depentanizer and the feed inlet of the C4 / C5 fractionation tower, respectively. The depentane tower is provided with a top gas reflux port at a position higher than the liquid phase reflux inlet, and the outlet of the pentane hydrogenation reactor is connected to the top gas reflux port through a pipeline after passing through the first heat exchanger. A valve is installed on the pipeline between the first heat exchanger and the gas reflux port at the top of the tower to control the flow rate of the gas reflux at the top of the tower. A valve is installed on the pipeline connecting the outlet of the pentane hydrogenation reactor to the air cooler after passing through the first heat exchanger. This valve is used to control the flow rate of the material entering the gas-liquid separator from the air cooler.

2. The apparatus according to claim 1, characterized in that, The apparatus also includes a C4 / C5 fractionation tower, in which the liquid product obtained from the gas-liquid separator is fractionated into C4 and C5 fractions.

3. The apparatus according to claim 1, characterized in that, The apparatus also includes a reformate hydrotreating reactor for hydrotreating the reformate fraction; the outlet of the reformate hydrotreating reactor is connected to the feed inlet of the depentanizer.

4. A method for producing foaming agent feedstock from pentane fraction in a catalytic reforming unit, characterized in that, The apparatus for producing foaming agent feedstock using the pentane fraction of the catalytic reforming unit as described in claim 1 or 2, the method comprising the following steps: (1) The reformed oil products enter the depentanizer, where C4 / C5 fractions are obtained at the top and C6+ fractions are obtained at the bottom. (2) Provide a pentane hydrogenation reactor; the C4 / C5 fraction obtained in step (1) is mixed with optional supplemental hydrogen, and after exchanging heat with the C4 / C5 fraction hydrogenation product in the first heat exchanger, it enters the pentane hydrogenation reactor and passes through the hydrogenation catalyst bed under hydrogenation conditions; (3) The hydrogenation product of the C4 / C5 fraction after cooling by the first heat exchanger is divided into two streams, one of which returns to the upper tray of the depentane tower through the gas phase reflux port. (4) The other route of the hydrogenation product of C4 / C5 fraction after cooling in the first heat exchanger is further cooled and then enters the gas-liquid separator to obtain gaseous and liquid products. (5) The liquid product obtained in step (4) is divided into two streams. One stream enters the downstream C4 / C5 fractionation tower, and the other stream is returned to the upper part of the depentane tower as liquid reflux through the liquid reflux port.

5. The method according to claim 4, characterized in that, The reformed oil product in step (1) is a hydrogenated product obtained by hydrogenating the reformed oil fraction, which contains unreacted hydrogen; or, the reformed oil product is a product obtained by refining the reformed oil fraction with clay.

6. The method according to claim 4, characterized in that, The C4 / C5 fraction hydrogenation products are returned to the depentanizer at a position 1-5 trays higher than the C4 / C5 liquid products.

7. The method according to claim 4, characterized in that, The operating conditions of the depentane degassing tower in step (1) include: top temperature of 80~120℃, bottom temperature of 180~225℃, and operating pressure of 0.8~1.2MPa.

8. The method according to claim 4, characterized in that, The hydrogenation conditions described in step (2) 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 ~15.0 h -1 The hydrogen-to-oil volume ratio is 0~20:

1.

9. The method according to claim 8, characterized in that, The hydrogenation conditions described in step (2) include: a reaction pressure of 0.8 MPa to 2.0 MPa, a reaction temperature of 100℃ to 160℃, 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.

10. The method according to claim 4, characterized in that, The hydrogenation catalyst uses alumina as a support and Pt and / or Pd as active components, with the content of the active components in the catalyst being 0.1% to 1.5% by weight.

11. The method according to claim 4, characterized in that, The volume ratio of the C4 / C5 fraction hydrogenation product returned to the top of the depentane tower in step (3) to the C4 / C5 fraction hydrogenation product entering the gas-liquid separator in step (4) is 1:4-1:

1.

12. The method according to claim 4, characterized in that, In step (4), the material used as liquid phase reflux accounts for 10-50% of the total mass fraction of the liquid product.

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