A catalytic hydrogenation process for the production of green renewable diesel with energy recovery

Abstract

The application provides a catalytic hydrogenation method for producing green renewable diesel fuel by recycling energy, and relates to the field of biofuel production. The application uses a new type of composite reactor for homogeneous hydrogenation pretreatment and secondary hydrogenation treatment, instead of a traditional process in which a suspension bed reactor or a fixed bed reactor is connected in series with a pipe reactor, the composite reactor uses chemical reaction heat release in the hydrogenation reaction process to heat the reactants, realizes reasonable utilization of waste heat, correspondingly saves the heat load of a heating furnace, is beneficial to reducing the comprehensive energy consumption of the device, and has high production efficiency.

Description

Technical Field

[0001] This invention relates to the field of biofuel production, and more particularly to a catalytic hydrogenation method for producing green renewable diesel by recovering energy. Background Technology

[0002] Green diesel is a second-generation biodiesel under development. Unlike first-generation biodiesel, which is composed of higher fatty acid methyl esters, green diesel is composed of higher aliphatic hydrocarbons, consistent with the main chemical composition of petroleum mineral diesel. Therefore, green diesel has greater potential as a substitute for mineral diesel. Green diesel is manufactured from raw materials through processes such as hydrogenation, isomerization, and purification. Among these processes, hydrogenation is crucial.

[0003] The chemical reaction in the catalytic hydrogenation of oil products is exothermic. Once the reaction begins, the heat released is sufficient to maintain the required active temperature of the reactants, with a surplus remaining. Therefore, after the materials enter the reactor, further heating is not necessary; in fact, the heat released must be controlled to ensure a balanced temperature rise within the reactor. Otherwise, excessive heat accumulation can affect the catalyst structure and performance, or even lead to safety accidents such as equipment burnout. There are generally two approaches to controlling the heat of reaction: one is to reduce the feed rate to control the amount of heat generated; the other is to add heat exchange functionality to the reactor to remove excess heat. Both methods have drawbacks. The former limits equipment capacity, reduces production efficiency, and has low economic benefits, while the latter increases equipment investment and complicates the production process.

[0004] In existing processes, the heat required to heat the materials entering the reactor comes from two sources: one is through a heat exchanger, where the high-temperature material carrying the heat of reaction exits the reactor indirectly transfers heat to the low-temperature raw material before it enters the reactor, thus achieving an initial temperature rise; the other is to use heating equipment to further heat the raw material after the initial temperature rise. However, the heat transfer efficiency of the former decreases as the temperature difference decreases during the heat transfer process, and the remaining heat of the high-temperature material is insufficient to raise the low-temperature raw material to the required temperature within the effective time. At this point, heating equipment is needed to continue heating, but the heating equipment suffers significant heat loss during the heating process, resulting in high production energy consumption.

[0005] Therefore, it is crucial to control the exothermic reaction and reduce the heating temperature of the feedstock during the oil hydrotreating process. Summary of the Invention

[0006] The purpose of this invention is to address the shortcomings of existing technologies by providing a catalytic hydrogenation method for producing green and renewable diesel fuel by recovering energy, thereby solving at least some of the problems existing in the prior art.

[0007] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0008] On one hand, a composite reactor for catalytic hydrogenation includes a shell and a tubular reactor disposed inside the shell; a solid catalyst bed is disposed between the shell and the tubular reactor; wherein,

[0009] The tubular reactor is a single-row spiral tube or a bundle of parallel straight tubes.

[0010] Furthermore, the composite reactor for catalytic hydrogenation also includes: a feed inlet, a discharge outlet, an ash discharge outlet, and a distribution plate; the feed inlet is located at the upper part of the shell and communicates with the pipeline reactor; the discharge outlet is located at the top of the shell; the ash discharge outlet is located at the bottom of the shell; and the distribution plate is located at the lower part of the solid catalyst bed.

[0011] On the other hand, a catalytic hydrogenation method for producing green renewable diesel fuel by recovering energy includes hydrogenating feedstock oil using the aforementioned composite reactor for catalytic hydrogenation.

[0012] Furthermore, the raw oil is selected from any one of gutter oil, vegetable oil, and animal oil.

[0013] Further, the hydrogenation treatment step is as follows:

[0014] (1) The raw oil in the raw material storage tank is pressurized by a pressurizing pump and mixed with hydrogen, and then heated by a reaction heating furnace; the liquid catalyst in the homogeneous catalyst storage tank is then pressurized and injected into the raw oil by a homogeneous catalyst injection pump, and then sent to the composite reactor for catalytic hydrogenation.

[0015] (2) After the feedstock is fed into the composite reactor for catalytic hydrogenation, it is first subjected to hydrogenation pretreatment in a pipeline reactor to obtain the pretreated product.

[0016] (3) The pretreated product flows out from the bottom of the pipeline reactor and enters the lower part of the shell. A small part of the heavy components in the material and the components of the liquid catalyst settle by gravity and are discharged from the ash discharge port. Most of the remaining material is returned upwards and, after being evenly distributed by the distribution plate, enters the solid catalyst bed for secondary hydrogenation treatment to obtain the secondary hydrogenation product, which is then collected from the discharge port.

[0017] In the secondary hydrogenation process, the pretreated products react in a solid catalyst bed. The heat released by the reaction is conducted to the material inside the tubular reactor through the tube wall, raising the temperature of the material inside the tube and realizing the comprehensive utilization of waste heat.

[0018] Furthermore, in step (1), the liquid catalyst is a nickel-based room-temperature fluidized catalyst, wherein the mass content of nickel metal element in the nickel-based room-temperature fluidized catalyst is 8-15%, preferably 13%, and the nickel-based room-temperature fluidized catalyst includes any one of nickel-molybdenum fluidized catalyst, nickel-cobalt fluidized catalyst, and nickel-molybdenum-cobalt fluidized catalyst.

[0019] Preferably, the molar ratio of nickel to molybdenum in the nickel-molybdenum flowable catalyst is 1:(0.1-0.5); the molar ratio of nickel to cobalt in the nickel-cobalt flowable catalyst is 1:(0.2-0.6); and the molar ratio of nickel, molybdenum, and cobalt in the nickel-molybdenum-cobalt flowable catalyst is 1:(0.03-0.1):(0.04-0.08).

[0020] Preferably, the fluidized catalyst needs to be treated with 13X molecular sieve before use. The treatment steps are as follows: mix 13X molecular sieve with the fluidized catalyst and treat at room temperature for 1 to 2 hours; the mass of 13X molecular sieve is 5.5 to 5.8% of the total mass of the fluidized catalyst, and the 13X molecular sieve is spherical with a particle size of 4 to 6 mm.

[0021] Furthermore, the amount of the liquid catalyst used is 200 to 2000 ppm.

[0022] Furthermore, in step (2), the processing conditions for the hydrogenation pretreatment process are as follows:

[0023] The temperature is 200–300℃;

[0024] The pressure is 2–10 MPa;

[0025] The hydrogen-to-oil volume ratio is 400–1000;

[0026] airspeed 10-20h -1 .

[0027] Furthermore, in step (3), the solid catalyst is a molybdenum-nickel-based alumina catalyst, which is either a molybdenum-nickel-alumina catalyst or a cobalt-molybdenum-nickel-alumina catalyst.

[0028] Preferably, the molybdenum-nickel alumina catalyst contains 5-15% molybdenum and 10-18% nickel.

[0029] Preferably, the cobalt-molybdenum-nickel alumina catalyst contains 5-10% cobalt, 3-8% molybdenum, and 5-12% nickel.

[0030] Furthermore, in step (3), the temperature of the secondary hydrogenation process is 300-400°C.

[0031] Furthermore, the above-mentioned catalytic hydrogenation method for producing green renewable diesel by recovering energy also includes the following steps:

[0032] (1) After the secondary hydrogenation product is collected from the outlet of the composite reactor for catalytic hydrogenation, it enters the hot high-pressure separator to separate hot high-pressure gas and hot high-pressure oil.

[0033] (2) The hot high-pressure oil enters the hot low-pressure separator to separate and remove the hydrotreated tailings, and then enters the fractionation tower after being heated by the fractionation heater.

[0034] (3) The hot high-pressure gas enters the cold high-pressure separator, and the separated hydrogenated oil is heated by the fractionation heater and then enters the fractionation tower;

[0035] (4) The material is fractionated in a fractionation tower to obtain green renewable diesel.

[0036] Preferably, in step (1), the temperature of the hot high-pressure separator is 230-330°C and the pressure is 1.9-9.5 MPa;

[0037] Preferably, in step (2), the temperature of the thermal low-pressure separator is 200-300°C and the pressure is 1-1.2 MPa;

[0038] Preferably, in step (3), the top pressure of the distillation column is 10-30 kPa, the feed temperature is 360-370°C, and the top temperature is 150-220°C.

[0039] Furthermore, the aforementioned catalytic hydrogenation method for producing green renewable diesel by recovering energy also includes:

[0040] Heavy components such as high-ash oil and tailings discharged from the bottom of the composite reactor and hot low-pressure separator for catalytic hydrogenation are discharged after hydrogen separation in the hot high-pressure separator for ash discharge and oil separation in the ash settling tank. The separated oil fractions, together with the unreacted oil fractions discharged from the bottom of the fractionation tower, are combined and returned to the beginning of the process as circulating oil, and then mixed into the feed oil for further hydrogenation treatment.

[0041] Compared with the prior art, the present invention has the following beneficial effects:

[0042] 1. The catalytic hydrogenation method for producing green renewable diesel fuel by recovering energy according to the present invention provides a new process for preparing green renewable diesel fuel through hydrogenation treatment.

[0043] 2. The catalytic hydrogenation method for producing green renewable diesel fuel by recovering energy in this invention proposes a novel composite reactor. This composite hydrogenation reactor utilizes the characteristic of a large temperature difference between adjacent parts within the reactor to achieve in-situ heat transfer of some of the chemical reaction heat within the reactor. This correspondingly reduces the heat exchange load of the heat exchangers installed outside the reactor in existing processes, reduces the heat loss that is difficult to avoid with external heat exchange, and saves on corresponding equipment investment.

[0044] 3. The catalytic hydrogenation method for producing green renewable diesel fuel by recovering energy in this invention has the advantage of a highly active liquid catalyst at low temperature, which reduces the temperature of the feedstock entering the reactor. In addition, the temperature-raising effect of heat transfer in the reactor can save 30% to 50% of the heat load of the heating furnace. Attached Figure Description

[0045] Figure 1 This is a flowchart of the catalytic hydrogenation method for producing green renewable diesel fuel by recovering energy according to the present invention;

[0046] Figure 1 In the diagram, 1-raw material storage tank, 2-pressurization pump, 3-reaction heating furnace, 4-homogeneous catalyst storage tank, 5-homogeneous catalyst injection pump, 6-composite reactor for catalytic hydrogenation, 7-hot high-pressure separator, 8-hot low-pressure separator, 9-cold high-pressure separator, 10-fractionation heating furnace, 11-fractionation tower, 12-circulating hydrogen compressor, 13-fresh hydrogen compressor, 14-ash discharge hot high-pressure separator, 15-ash settling tank.

[0047] Figure 2 and Figure 3 This is a schematic diagram of the structure of the composite reactor for catalytic hydrogenation of the present invention;

[0048] Figure 2 and Figure 3 In the middle, 16-single row spiral tube, 17-parallel straight tube bundle, 18-shell, 19-feed inlet, 20-discharge outlet, 21-ash discharge port, 22-solid catalyst bed, 23-distribution plate. Detailed Implementation

[0049] The following non-limiting embodiments are intended to enable those skilled in the art to gain a more comprehensive understanding of the present invention, but do not limit the invention in any way. The following description is merely an exemplary illustration of the scope of protection of the present invention, and those skilled in the art can make various changes and modifications to the invention based on the disclosed content, which should also fall within the scope of protection of the present invention.

[0050] like Figure 2 , Figure 3As shown, a specific embodiment of the present invention provides a composite reactor for catalytic hydrogenation, including a shell 18 and a tubular reactor disposed inside the shell 18; the tubular reactor is a single row of spiral tubes 16 or composed of parallel straight tube bundles 17; a solid catalyst bed 22 is disposed between the shell 18 and the tubular reactor.

[0051] Specifically, the composite reactor for catalytic hydrogenation also includes: a feed inlet 19, a discharge outlet 20, an ash discharge outlet 21, and a distribution plate 23; the feed inlet 19 is located at the upper part of the shell 18 and is connected to the pipeline reactor; the discharge outlet 20 is located at the top of the shell 18; the ash discharge outlet 21 is located at the bottom of the shell 18; and the distribution plate 23 is located at the lower part of the solid catalyst bed inside the shell 18.

[0052] The composite reactor for catalytic hydrogenation of this invention embeds a single-row helical tube or parallel straight tube bundle (hereinafter referred to as tubular structure) within a solid catalyst bed. Within this reactor, the material undergoes a homogeneous reaction at a lower temperature within the tubular structure and a heterogeneous reaction at a higher temperature on the fixed bed. Through this two-stage reaction process, the heat of chemical reaction generated in the fixed bed is conducted through the tube walls to the material inside the tubes, raising the temperature of the material inside to the reaction activation temperature, thus achieving efficient utilization of the heat of chemical reaction.

[0053] like Figure 1 As shown in the specific embodiment of the present invention, a catalytic hydrogenation method for producing green renewable diesel fuel by recovering energy is provided, comprising the following steps:

[0054] S1. The feedstock oil enters the composite reactor 6 for catalytic hydrotreating:

[0055] (1) The raw oil in the raw material storage tank 1 is pressurized by the pressurizing pump 2 and mixed with hydrogen, and then heated by the reaction heating furnace 3; the liquid catalyst in the homogeneous catalyst storage tank 4 is pressurized and injected into the raw oil by the homogeneous catalyst injection pump 5, and then sent to the composite reactor 6 for catalytic hydrogenation.

[0056] (2) The feedstock is first hydrogenated in the pipeline reactor 16 or 17 of the composite reactor 6 for catalytic hydrogenation to obtain the pretreated product.

[0057] (3) The pretreated product flows out through the lower end of the pipeline reactor 16 or 17 and enters the lower part of the shell for sedimentation. A small portion of the heavy components and liquid catalyst components are deposited here and discharged from the ash discharge port 21. The remaining main materials are returned upwards and, after being evenly distributed by the distribution plate 23, enter the solid catalyst bed 22 for secondary hydrogenation treatment to obtain the secondary hydrogenation product, which is then collected from the discharge port 20.

[0058] During the secondary hydrogenation process, the pretreated products react in the solid catalyst bed 22. The heat released by the reaction is conducted to the material inside the pipe through the pipe wall of the tubular reactor 16 or 17, recovering the heat of reaction and realizing the comprehensive utilization of waste heat.

[0059] S2. After the secondary hydrogenation product is collected from the outlet 20 of the composite reactor 6 for catalytic hydrogenation, it enters the hot high-pressure separator 7 to separate hot high-pressure gas and hot high-pressure oil.

[0060] S3. The hot high-pressure oil enters the hot low-pressure separator 8 to separate and remove the hydrotreated tailings, and then enters the fractionation tower 11 after being heated by the fractionation heater 10.

[0061] S4. The hot high-pressure gas enters the cold high-pressure separator 9. The separated hydrogenated oil is heated by the fractionation heater 10 and then enters the fractionation tower 11.

[0062] S5. The material undergoes component fractionation in fractionation tower 11 to finally obtain green and renewable diesel.

[0063] Heavy components such as high-ash oil and tailings discharged from the bottom of the catalytic hydrogenation composite reactor 6 and the hot low-pressure separator 8 are discharged after being separated by the ash settling tank 15. The separated oil is combined with the unreacted oil discharged from the bottom of the fractionation tower 11 and returned to the beginning of the process as circulating oil, and then mixed into the feed oil for further hydrogenation treatment.

[0064] In this application, the liquid catalyst is prepared according to existing processes, and there are no special limitations as long as the composition and content of the liquid catalyst are met. For example, the liquid catalyst can be prepared by fully grinding and mixing the corresponding metal salt and then adding an organic acid. The corresponding nickel metal salt can be selected from any one of nickel carbonate, nickel acetate, nickel sulfate, and nickel nitrate; the molybdenum metal salt can be selected from any one of ammonium heptamolybdate, ammonium tetramolybdate, and sodium heptamolybdate; and the cobalt metal salt can be selected from any one of cobalt acetate, cobalt carbonate, and cobalt nitrate. The specific preparation method of the liquid catalyst and the specific types of metal salts mentioned above do not constitute a limitation on this application. In the specific embodiments section of this application, the liquid catalyst is prepared by fully grinding and mixing the corresponding metal salt and then adding an organic acid. The corresponding nickel metal salt is selected from nickel nitrate, the cobalt metal salt is selected from cobalt nitrate, and the molybdenum metal salt is selected from ammonium heptamolybdate.

[0065] The present invention will be further described below by way of specific embodiments. Unless otherwise specified, all chemical reagents used in the embodiments of the present invention are obtained through conventional commercial means.

[0066] Example 1

[0067] A catalytic hydrogenation method for producing green renewable diesel fuel by recovering energy includes the following steps:

[0068] S1. The feedstock oil (waste cooking oil) enters the catalytic hydrotreating composite reactor for hydrotreating:

[0069] (1) After the feedstock is pressurized by a pressurizing pump, hydrogen is mixed in and then heated in a heating furnace. Liquid catalyst is injected into the feedstock at a concentration of 200 ppm and then sent to a composite reactor for catalytic hydrogenation.

[0070] The liquid catalyst is a nickel-molybdenum flowable catalyst, wherein the molar ratio of nickel to molybdenum is 1:0.5, and the mass content of nickel is 13%.

[0071] (2) The feedstock oil is first subjected to hydrotreating in pipeline reactor 16 to obtain the pretreated product. The hydrotreating conditions are: temperature 300℃, hydrogen pressure 2MPa, hydrogen-to-oil volume ratio of 400, and space velocity of 20h. -1 .

[0072] (3) The pretreated product flows out from the bottom of the pipeline reactor and enters the lower part of the shell for sedimentation. A small portion of the heavy components and liquid catalyst components are deposited here and discharged from the ash discharge port. The remaining main materials are returned upwards and, after being evenly distributed by the distribution plate, enter the solid catalyst bed and undergo secondary hydrogenation treatment at 400°C to obtain the secondary hydrogenation product, which is then collected from the discharge port.

[0073] The solid catalyst is a molybdenum-nickel alumina catalyst, wherein the content of molybdenum metal element is 5% and the content of nickel metal element is 18%.

[0074] S2. After the secondary hydrogenation product is collected from the outlet of the composite reactor for catalytic hydrogenation, it enters the hot high-pressure separator, where hot high-pressure gas and hot high-pressure oil are separated at a temperature of 330℃ and a pressure of 9.5MPa.

[0075] S3. The hot high-pressure oil enters the hot low-pressure separator, where it is separated and the hydrotreated tailings are removed at a temperature of 300℃ and a pressure of 1.2MPa. Then, it is heated by the fractionation heater and enters the fractionation tower. The top pressure of the fractionation tower is 30KPa, the feed temperature is 370℃, and the top temperature is 220℃.

[0076] S4. The hot high-pressure gas enters the cold high-pressure separator. The hydrotreated oil separated at 70°C and 1MPa is heated in the fractionation furnace and then enters the fractionation tower.

[0077] S5. The material undergoes component fractionation in a fractionation tower to obtain green and renewable diesel oil;

[0078] S6. Heavy components such as high-ash oil and tailings discharged from the bottom of the composite reactor and hot low-pressure separator for catalytic hydrogenation are discharged after hydrogen separation in the hot high-pressure separator for ash discharge and oil separation in the ash settling tank. The separated oil fractions, together with the unreacted oil fractions discharged from the bottom of the fractionation tower, are combined and returned to the initial end of the process as circulating oil, and then mixed into the feed oil for further hydrogenation treatment.

[0079] Example 2

[0080] A green, renewable diesel catalytic hydrogenation method for recovering energy includes the following steps:

[0081] S1. The feedstock oil (coconut oil) enters a combined reactor for catalytic hydrotreating for hydrotreating:

[0082] (1) After the feedstock is pressurized by a pressurizing pump, hydrogen is mixed in and then heated in a heating furnace. Liquid catalyst is injected into the feedstock at a concentration of 1000 ppm and then sent to a composite reactor for catalytic hydrogenation.

[0083] The liquid catalyst is a nickel-cobalt flowable catalyst, wherein the molar ratio of nickel to cobalt is 1:0.6, and the mass content of nickel is 13%.

[0084] (2) The feedstock oil is first subjected to hydrogenation pretreatment in pipeline reactor 17 to obtain the pretreated product; the temperature is 200℃, the hydrogen pressure is 10MPa, the hydrogen-to-oil volume ratio is 1000, and the space velocity is 10h. -1 .

[0085] (3) The pretreated product flows out from the bottom of the pipeline reactor and enters the bottom of the shell for sedimentation. A small portion of the heavy components and liquid catalyst components are deposited here and discharged from the ash outlet. The remaining main materials are returned upwards and, after being evenly distributed by the distribution plate, enter the solid catalyst bed for secondary hydrogenation treatment to obtain the secondary hydrogenation product, which is then collected from the outlet. The secondary hydrogenation treatment conditions are: temperature 200℃.

[0086] The solid catalyst is a cobalt-molybdenum-nickel alumina catalyst, with a molybdenum metal content of 3%, a cobalt metal content of 10%, and a nickel metal content of 12%.

[0087] S2. After the secondary hydrogenation product is collected from the outlet of the composite reactor for catalytic hydrogenation, it enters the hot high-pressure separator, where hot high-pressure gas and hot high-pressure oil are separated at a temperature of 230℃ and a pressure of 1.9MPa.

[0088] S3. The hot high-pressure oil enters the hot low-pressure separator, where it is separated and the hydrotreated tailings are removed at a temperature of 200℃ and a pressure of 1MPa. Then, it is heated by the fractionation heater and enters the fractionation tower. The top pressure of the fractionation tower is 10KPa, the feed temperature is 360℃, and the top temperature is 150℃.

[0089] S4. The hot high-pressure gas enters the cold high-pressure separator. The hydrotreated oil separated at 50°C and 6MPa is heated in the fractionation furnace and then enters the fractionation tower.

[0090] S5. The material undergoes component fractionation in a fractionation tower to obtain green and renewable diesel oil;

[0091] S6. Heavy components such as high-ash oil and tailings discharged from the bottom of the composite reactor and hot low-pressure separator for catalytic hydrogenation are discharged after hydrogen and oil separation by the ash discharge hot high-pressure separator. The separated oil is combined with the unreacted oil discharged from the bottom of the fractionation tower and returned to the beginning of the process as circulating oil, and then mixed into the feed oil for further hydrogenation treatment.

[0092] Example 3

[0093] A green, renewable diesel catalytic hydrogenation method for recovering energy includes the following steps:

[0094] S1. The feedstock oil (waste cooking oil) enters the composite reactor for hydrogenation treatment:

[0095] (1) After the feed oil is pressurized by a pressurizing pump, it is mixed with hydrogen and then heated in a heating furnace. Liquid catalyst is injected into the feed oil at a concentration of 2000 ppm and then sent to a composite reactor.

[0096] The liquid catalyst is a nickel-molybdenum-cobalt flowable catalyst, wherein the molar ratio of nickel:molybdenum:cobalt is 1:0.03:0.08, and the mass content of nickel is 13%.

[0097] (2) The feedstock oil is first subjected to hydrogenation pretreatment in pipeline reactor 17 to obtain the pretreated product; the temperature is 200℃, the hydrogen pressure is 10MPa, the hydrogen-to-oil volume ratio is 1000, and the space velocity is 10h. -1 .

[0098] (3) The pretreated product flows out from the lower end of the tubular reactor and enters the bottom of the shell for sedimentation. A small portion of the heavy components and liquid catalyst components are deposited here and discharged from the ash discharge port. The remaining main materials are returned upwards and, after being evenly distributed by the distribution plate, enter the solid catalyst bed for secondary hydrogenation treatment to obtain the secondary hydrogenation product, which is then collected from the discharge port. The secondary hydrogenation treatment conditions are: temperature 200℃, volume hourly space velocity 5h. -1 .

[0099] The solid catalyst is a molybdenum-nickel alumina catalyst, wherein the content of molybdenum metal element is 15% and the content of nickel metal element is 10%.

[0100] S2. After the secondary hydrogenation product is collected from the outlet of the composite reactor for catalytic hydrogenation, it enters the hot high-pressure separator, where hot high-pressure gas and hot high-pressure oil are separated at a temperature of 330℃ and a pressure of 9.5MPa.

[0101] S3. The hot high-pressure oil enters the hot low-pressure separator, where it is separated and the hydrotreated tailings are removed at a temperature of 300℃ and a pressure of 1.2MPa. Then, it is heated by the fractionation heater and enters the fractionation tower. The top pressure of the fractionation tower is 30KPa, the feed temperature is 370℃, and the top temperature is 220℃.

[0102] S4. The hot high-pressure gas enters the cold high-pressure separator. The hydrotreated oil separated at 70°C and 1MPa is heated in the fractionation furnace and then enters the fractionation tower.

[0103] S5. The material undergoes component fractionation in a fractionation tower to obtain green and renewable diesel oil;

[0104] S6. Heavy components such as high-ash oil and tailings discharged from the bottom of the composite reactor and hot low-pressure separator for catalytic hydrogenation are discharged after hydrogen and oil separation by the ash discharge hot high-pressure separator. The separated oil is combined with the unreacted oil discharged from the bottom of the fractionation tower and returned to the beginning of the process as circulating oil, and then mixed into the feed oil for further hydrogenation treatment.

[0105] The properties of the feedstock oils in Examples 1, 2, and 3 above are shown in Table 1 below:

[0106] Table 1. Properties of Feed Oil

[0107] project gutter oil Coconut oil <![CDATA[Density (20°C) (g / cm 3 )]]> 0.83 0.90 <![CDATA[Kinematic Viscosity (50°C) (mm 2 / s)]]> 32.90 58.31 S content (μg / g) 153.0 2.1 Nitrogen content (μg / g) 219.0 2.0 O content (μg / g) 9.8 13.9 Acid value (mgKOH / g) 168.0 0.9

[0108] Example 4

[0109] The difference from Example 1 is that the composition of the nickel-molybdenum fluidized catalyst in the hydrogenation pretreatment process is different. In this example, the molar ratio of nickel to molybdenum in the nickel-molybdenum fluidized catalyst is 1:0.1.

[0110] Example 5

[0111] The difference from Example 2 is that the composition of the nickel-cobalt fluidized catalyst in the hydrogenation pretreatment process is different. In this example, the molar ratio of nickel to cobalt in the nickel-cobalt fluidized catalyst is 1:0.2; the solid catalyst in the secondary hydrogenation treatment is a cobalt-molybdenum-nickel alumina catalyst with a molybdenum metal content of 8%, a cobalt metal content of 5%, and a nickel metal content of 5%.

[0112] Example 6

[0113] The difference from Example 3 is that the composition of the nickel-molybdenum-cobalt fluidized catalyst in the hydrogenation pretreatment process is different. In this example, the molar ratio of nickel, molybdenum and cobalt in the nickel-molybdenum-cobalt fluidized catalyst is 1:0.1:0.04.

[0114] Example 7

[0115] The difference from Example 1 is that, in the hydrogenation pretreatment process, 13X molecular sieves were added to the catalyst before use and treated at room temperature for 2 hours. The mass of 13X molecular sieves was 5.5% of the total mass of the fluidized catalyst. The 13X molecular sieves were spherical with a particle size of 4 mm.

[0116] Example 8

[0117] The difference from Example 1 is that, in the hydrogenation pretreatment process, 13X molecular sieve was added to the nickel-molybdenum fluid catalyst before use and treated at room temperature for 1 hour. The mass of 13X molecular sieve was 5.8% of the total mass of the fluid catalyst. The 13X molecular sieve was spherical with a particle size of 6 mm.

[0118] Example 9

[0119] The difference from Example 7 is that, in the process of treating the nickel-molybdenum flowable catalyst with 13X molecular sieve, the mass of 13X molecular sieve is 5.1% of the total mass of the flowable catalyst.

[0120] Example 10

[0121] The difference from Example 7 is that, in the process of treating the nickel-molybdenum flowable catalyst with 13X molecular sieve, the mass of 13X molecular sieve is 6.2% of the total mass of the flowable catalyst.

[0122] Comparative Example 1

[0123] The difference from Example 1 is that the composite reactor in this comparative example is replaced by a two-step hydrogenation process consisting of a tubular reactor and a fixed-bed reactor connected in series. The hydrogenation process is as follows:

[0124] (1) The raw oil (waste oil) is pressurized by a pressurizing pump and mixed with hydrogen. Then it is heated in a heating furnace. Liquid catalyst (same as in Example 1) is injected into the raw oil at a pressure of 200 ppm and then sent to a pipeline reactor.

[0125] (2) The feedstock oil is subjected to hydrotreating in a pipeline reactor (pipeline reactor 16 is used as an example in this comparative example) to obtain the pretreated product; the hydrotreating conditions remain unchanged.

[0126] (3) The pretreated product flows out from the top of the pipeline reactor and enters the fixed bed reactor for secondary hydrogenation treatment to obtain the secondary hydrogenation product; the secondary hydrogenation treatment conditions remain unchanged.

[0127] Comparative Example 2

[0128] The difference from Example 1 is that the composite reactor in this comparative example is replaced by a two-step hydrogenation process consisting of a suspended bed hydrocracking reactor and a fixed bed reactor connected in series; that is, the steps of the green renewable diesel catalytic hydrogenation method for recovering energy are as follows:

[0129] S1. The feedstock oil (waste cooking oil) is pressurized by a pressure pump, mixed with hydrogen, and then heated in a heater before entering a suspended bed hydrocracking reactor for hydrogenation. The reaction conditions are: temperature 300℃, hydrogen pressure 2MPa, hydrogen-to-oil volume ratio 400, and space velocity 20h⁻¹. -1 .

[0130] The catalyst added to the suspended bed hydrocracking reactor is a nickel-molybdenum fluidized catalyst, the same as in Example 1.

[0131] S2. The reaction product flowing out from the top of the suspended bed hydrocracking reactor enters the fixed bed reactor for secondary hydrogenation treatment to obtain secondary hydrogenation product; the secondary hydrogenation treatment conditions remain unchanged.

[0132] The catalyst added to the fixed-bed reactor is a molybdenum-nickel alumina catalyst, the same as in Example 1.

[0133] S3. The secondary hydrogenation product flows out of the fixed bed reactor and enters the hot high-pressure separator to separate hot high-pressure gas and hot high-pressure oil.

[0134] S4. The hot high-pressure oil enters the hot low-pressure separator to separate and remove the hydrotreating tailings, and then is heated by the fractionation heater before entering the fractionation tower.

[0135] S5. The hot high-pressure gas enters the cold high-pressure separator. The separated hydrogenated oil is heated by the fractionation heater and then enters the fractionation tower.

[0136] S6. The material undergoes component fractionation in a fractionation tower to obtain green and renewable diesel.

[0137] Comparative Example 3

[0138] The difference from Comparative Example 1 is that the composite reactor in this comparative example is replaced with a suspended bed hydrocracking reactor, i.e., the steps of the green renewable diesel catalytic hydrotreating method for energy recovery are as follows:

[0139] S1. The feedstock oil (waste cooking oil) is pressurized by a pressure pump, mixed with hydrogen, and then heated in a heater before entering a suspended bed hydrocracking reactor for hydrogenation. The reaction conditions are: temperature 300℃, hydrogen pressure 2MPa, hydrogen-to-oil volume ratio 400, and space velocity 20h⁻¹. -1 .

[0140] The catalyst added to the suspended bed hydrocracking reactor is a nickel-molybdenum fluidized catalyst, the same as in Example 1.

[0141] S2. The reaction products flowing out from the top of the suspended bed hydrocracking reactor enter the hot high-pressure separator to separate hot high-pressure gas and hot high-pressure oil.

[0142] S3. The hot high-pressure oil enters the hot low-pressure separator to separate and remove the hydrotreated tailings, and then is heated by the fractionation heater before entering the fractionation tower.

[0143] S4. The hot high-pressure gas enters the cold high-pressure separator. The separated hydrogenated oil is heated by the fractionation heater and then enters the fractionation tower.

[0144] S5. The material undergoes component fractionation in a fractionation tower to obtain green and renewable diesel.

[0145] Comparative Example 4

[0146] The difference from Comparative Example 1 is that the catalytic hydrogenation composite reactor in this comparative example does not have a fixed catalyst bed. The steps of the green renewable diesel catalytic hydrogenation method for recovering energy are as follows:

[0147] S1. The feedstock oil (waste cooking oil) is pressurized by a pressure pump and mixed with hydrogen. It is then heated in a furnace, and a liquid catalyst is injected into the feedstock oil at a concentration of 200 ppm under pressure. The mixture then enters a pipeline reactor for hydrogenation. The reaction conditions are: temperature 300℃, hydrogen pressure 2 MPa, hydrogen-to-oil volume ratio 400, and space velocity 20 h⁻¹. -1 .

[0148] S2. The reaction products flowing out from the top of the pipeline reactor enter the hot high-pressure separator to separate hot high-pressure gas and hot high-pressure oil.

[0149] S3. The hot high-pressure oil enters the hot low-pressure separator to separate and remove the hydrotreated tailings, and then is heated by the fractionation heater before entering the fractionation tower.

[0150] S4. The hot high-pressure gas enters the cold high-pressure separator. The separated hydrogenated oil is heated by the fractionation heater and then enters the fractionation tower.

[0151] S5. The material undergoes component fractionation in a fractionation tower to obtain green and renewable diesel.

[0152] Comparative Example 5

[0153] The difference from Comparative Example 1 is that the catalytic hydrogenation in this comparative example is replaced by a fixed-bed reactor instead of a composite reactor. The steps of the green renewable diesel catalytic hydrogenation method for energy recovery are as follows:

[0154] S1. The feedstock oil (waste cooking oil) is pressurized by a pressurizing pump and mixed with hydrogen. It is then heated in a heating furnace and enters a fixed-bed reactor for hydrogenation reaction.

[0155] The catalyst added to the fixed-bed reactor is a nickel-molybdenum fluidized catalyst, the same as in Example 1.

[0156] S2. The reaction products flowing out of the fixed-bed reactor enter the hot high-pressure separator to separate hot high-pressure gas and hot high-pressure oil.

[0157] S3. The hot high-pressure oil enters the hot low-pressure separator to separate and remove the hydrotreated tailings, and then is heated by the fractionation heater before entering the fractionation tower.

[0158] S4. The hot high-pressure gas enters the cold high-pressure separator. The separated hydrogenated oil is heated by the fractionation heater and then enters the fractionation tower.

[0159] S5. The material undergoes component fractionation in a fractionation tower to obtain green and renewable diesel.

[0160] Experimental Example 1

[0161] The hydrogenation products and final diesel products obtained from the above embodiments and comparative examples were tested, and the results are shown in Table 2 below.

[0162] Table 2. Hydrotreating Results and Diesel Quality

[0163]

[0164] The results show that, compared with the process provided in the comparative example, the green renewable diesel catalytic hydrogenation method for recovering energy provided by this invention has a feed conversion rate of over 99% in the hydrogenation process, which is high; the diesel produced has low sulfur content, high cetane number, low acid value, and high alkane content, resulting in high diesel product quality.

[0165] The above description of the embodiments is provided to enable those skilled in the art to understand and use the invention. It will be apparent to those skilled in the art that various modifications can be made to these embodiments, and the general principles described herein can be applied to other embodiments without inventive effort. Therefore, the present invention is not limited to the above embodiments, and any improvements and modifications made by those skilled in the art based on the disclosure of the present invention without departing from the scope of the invention should be within the protection scope of the present invention.

Claims

1. A catalytic hydrogenation method for producing green renewable diesel fuel by recovering energy, characterized in that, This includes using a composite reactor for catalytic hydrogenation to hydrogenate feedstock oil; the composite reactor for catalytic hydrogenation includes: a shell and a tubular reactor disposed inside the shell; a solid catalyst bed is disposed between the shell and the tubular reactor; wherein, the tubular reactor is a single-row helical tube or composed of parallel straight tube bundles; it also includes an inlet, an outlet, an ash discharge port, and a distribution plate; the inlet is located at the upper part of the shell and communicates with the tubular reactor; the outlet is located at the top of the shell; the ash discharge port is located at the bottom of the shell; the distribution plate is located at the lower part of the solid catalyst bed; The hydrogenation treatment steps are as follows: (1) The raw oil in the raw material storage tank is pressurized by a pressurizing pump and mixed with hydrogen, and then heated by a reaction heating furnace; the liquid catalyst in the homogeneous catalyst storage tank is pressurized and injected into the raw oil by a homogeneous catalyst injection pump, and then sent to the composite reactor for catalytic hydrogenation. The raw oil is selected from any one of gutter oil, vegetable oil, and animal oil. (2) After the feedstock oil is fed into the composite reactor for catalytic hydrogenation, it is first subjected to hydrogenation pretreatment in a pipeline reactor to obtain the pretreated product; (3) The pretreated product flows out from the bottom of the pipeline reactor and enters the bottom of the shell for sedimentation. The heavy components and liquid catalyst fine particles are deposited here and discharged from the ash discharge port. The remaining materials are returned upward and, after being evenly distributed by the distribution plate, enter the solid catalyst bed for secondary hydrogenation treatment to obtain the secondary hydrogenation product, which is then collected from the discharge port. In step (1), the liquid catalyst is a nickel-based room-temperature fluid catalyst; the liquid catalyst needs to be treated with 13X molecular sieve before use. The treatment steps are: mix 13X molecular sieve with liquid catalyst and treat at room temperature for 1 to 2 hours; the mass of 13X molecular sieve is 5.5 to 5.8% of the liquid catalyst.

2. The catalytic hydrogenation method for producing green renewable diesel fuel by recovering energy according to claim 1, characterized in that, During the secondary hydrogenation process, the pretreated products react in a solid catalyst bed. The heat released by the reaction is conducted to the material inside the tubular reactor through the tube wall, raising the temperature of the material inside the tube and realizing comprehensive utilization of waste heat.

3. The catalytic hydrogenation method for producing green renewable diesel fuel by recovering energy according to claim 1, characterized in that, The 13X molecular sieve is spherical with a particle size of 4–6 mm.

4. The catalytic hydrogenation method for producing green renewable diesel fuel by recovering energy according to claim 1, characterized in that, The catalytic hydrogenation method for producing green renewable diesel by recovering energy also includes the following steps: (1) After the secondary hydrogenation product is collected from the outlet of the composite reactor for catalytic hydrogenation, it enters the hot high-pressure separator to separate the hot high-pressure gas and hot high-pressure oil. (2) The hot high-pressure oil enters the hot low-pressure separator to separate and remove the hydrotreated tailings, and then enters the fractionation tower after being heated by the fractionation heater. (3) The hot high-pressure gas enters the cold high-pressure separator, and the separated hydrogenated oil is heated by the fractionation heater and then enters the fractionation tower; (4) The material is fractionated in a fractionation tower to obtain green renewable diesel.

5. The catalytic hydrogenation method for producing green renewable diesel fuel by recovering energy according to claim 4, characterized in that, It also includes the following steps: The high-ash oil and heavy components of the tailings discharged from the bottom of the composite reactor and the hot low-pressure separator for catalytic hydrogenation are discharged after being separated by the ash settling tank. The separated oil, together with the unreacted oil discharged from the bottom of the fractionation tower, is combined and returned to the beginning of the process as circulating oil, and then mixed into the feed oil for further hydrogenation treatment.

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