JP2013256601A - System and method for producing light oil - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a system for producing light oil capable of improving yield of light oil than the conventional art.SOLUTION: A system for producing light oil includes: a filter for filtering raw material oil; a pre-heater for pre-heating the filtered raw material oil; a reactor including a solid catalyst with which the pre-heated raw material oil is brought into contact to be converted into cracked oil comprising hydrocarbons; a high temperature fractionating column condensing heavy oil (heavy fraction) from the cracked oil to feed hydrocarbon oil other than the condensed heavy oil in a gas state to a rear stage; a recirculation section for recirculating the heavy oil to the reactor, the heavy oil having being condensed in the high temperature fractionating column to be separated; a low temperature fractionating column for condensing cracked oil (gas oil fraction) with light oil quality from the hydrocarbon oil in a gas state having been fed from the high temperature fractionating column and discharging a naphtha/gas component other than the condensed cracked oil (gas oil fraction) with light oil quality to a rear stage; a cooling column for cooling the cracked oil (gas oil fraction) with light oil quality having been condensed (fractionally distilled) in the low temperature fractionating column; and a light oil recovery section for recovering the light oil having been obtained by being cooled in the cooling column.

Description

  The present invention relates to a light oil production system and a light oil production method produced using a solid catalyst. In particular, the present invention relates to a light oil production system and a light oil production method using a catalytic cracking method, which can use waste edible oil, vegetable oil, animal oil, and various mineral oils as a raw material for light oil. is there.

  As a method for producing light oil using fats and oils such as waste cooking oil, there is a catalytic cracking method (for example, Patent Document 1). In this catalytic cracking method, it decomposes into light oils such as light oily hydrocarbons, carbon dioxide, propane, etc., by a decarboxylation cracking reaction that cleaves the ester bond part of fats and oils by the action of a solid catalyst. Patent Document 1 discloses a light oil production system that enables small-scale processing by reaction under normal pressure.

JP 2011-032408 A

  However, in Patent Document 1, fractional loss and heavy oil (min) generated in each fractionation step after the catalytic reaction step are used as a heat source for the reaction, so the yield of light oil is further improved. There is a request to want.

  Then, this invention is made | formed in view of the said condition, The objective is to provide the light oil manufacturing system and light oil manufacturing method which can improve the yield of light oil conventionally.

The light oil production system of the present invention comprises:
A raw material tank for storing raw material oil;
A filter for filtering the raw oil;
A preheater for preheating the raw oil filtered by the filter;
A reactor having a solid catalyst that contacts the feed oil preheated by the preheater and converts it into cracked oil comprising hydrocarbons;
A high-temperature fractionating tower that condenses heavy oil (heavy fraction) from the cracked oil obtained in the reactor and sends hydrocarbon oil other than the condensed heavy oil in a gaseous state to the subsequent stage;
A reflux section for refluxing the heavy oil condensed and separated in the high-temperature fractionating column to the reactor;
Gas oil cracked oil (light oil fraction) is condensed from the gaseous hydrocarbon oil sent from the high temperature fractionating tower, and naphtha gas components other than the condensed light oil cracked oil are passed to the subsequent stage. A low-temperature fractionating tower to be discharged;
A cooling tower that cools the light oily cracked oil (light oil fraction) condensed (fractionated) in the low-temperature fractionating tower;
A light oil recovery section for recovering light oil obtained by cooling in the cooling tower.

  According to the above configuration, the heavy oil (heavy fraction) separated in the high-temperature fractionation tower is refluxed to the reactor, and is subjected to catalytic cracking reaction again in the reactor to be decomposed into naphtha, kerosene, and light oil. The yield of light oil as a whole system can be improved as compared with the conventional system. In addition, it is no longer necessary to install a heavy oil (heavy fraction) recovery device (for example, a discharge valve, a recovery tank, etc.) that was conventionally required.

  The raw material oil is, for example, a simple or mixed waste cooking oil, vegetable oil, animal oil, and various mineral oils. Examples of the waste cooking oil include tempura oil and fried oil. Examples of vegetable oils include rapeseed oil, soybean oil, sesame oil, safflower oil, cottonseed oil, rice oil, peanut oil, sunflower oil, corn oil, olive oil, palm oil, coconut oil, jatropha oil, peanut oil and the like. Examples of animal fats include beef tallow (hett), pork oil (lard) and the like. Examples of the mineral oil include various hydrocarbon-based mineral oils.

  The foreign material is removed from the raw oil using a filter. By removing the foreign matter in the raw material oil, it is possible to prevent a reduction in the efficiency of the catalytic cracking reaction due to the foreign matter adhering to the solid catalyst. As filtration performance, it can comprise with a filter of about 0.5 micrometer-5 micrometers, and about 1 micrometer is preferred. Examples of the foreign material include heaven waste in tempura oil. In addition, you may store raw material oil in a raw material oil tank, after filtering with a filter beforehand.

  The raw material oil is preheated with a preheater. The temperature of the heated raw material oil is a temperature range in which vaporization does not occur, and a temperature range in which a catalytic reaction is efficiently performed is preferable. For example, a temperature range of 200 to 400 ° C, preferably a temperature range of 300 to 350 ° C. is there. Since the raw material oil is preheated and kept in the catalytic reaction temperature range while being liquid, it is preferable because there is no oxidative deterioration due to vaporization.

The catalyst used in the catalytic cracking method is a solid catalyst. Examples of the solid catalyst include zeolite, ion exchange resin, lime, clay, metal oxide, metal carbonate, composite oxide such as SiO ₂ —MgO and SiO ₂ —CaO, or supported metal oxide, and the like. A supported metal oxide of SiO ₂ —MgO is preferred. When this supported metal oxide of SiO ₂ —MgO is used, the yield of the obtained diesel fuel (light oil) is preferably 60% or more. In addition, the method for fixing the solid catalyst is not particularly limited, and the fixed catalyst reactor is configured by fixing the solid catalyst to the fixing member.

  The cracked oil obtained by reacting the raw material oil in the fixed catalyst reactor is subjected to two-stage fractionation using a high-temperature fractionation tower and a low-temperature fractionation tower. The fractionation temperature range of the high-temperature fractionation tower is a preferred temperature range for separating a boiling point component higher than light oil, and is, for example, 240 to 360 ° C, preferably 250 to 350 ° C. The low-temperature fractionation column is a fractionation temperature range lower than the fractionation temperature range of the high-temperature fractionation column, and is a preferable temperature range for separating boiling components below light oil, for example, 120 ° C to 200 ° C. A temperature range is preferable, and a temperature range of 140 ° C to 170 ° C is more preferable.

  By the two-stage fractionation, hydrocarbon oils such as combustible gas components, naphtha / kerosene / light oil, and residues (coke) are continuously fractionated. And the light oil fraction (gaseous form) obtained in the low temperature fractionation tower is cooled in the cooling tower to obtain liquid light oil (diesel fuel), which is recovered in a recovery part (for example, a storage tank). The light oil produced by the present invention is light oil that conforms to the JIS K2204 standard, and is distinguished from conventional biodiesel fuel (BDF (registered trademark)) and light oil substitute fuel.

  Moreover, in one Embodiment of the said invention, it further has the supply line which supplies the said naphtha gas component discharged | emitted from the said low temperature fractionation column to the said preheater, and utilizes it as a heat source.

  According to this configuration, since the naphtha gas component (including kerosene) can be used as a heat source for the preheater, the thermal energy utilization efficiency of the entire system becomes high, and cracked oil (hydrocarbon oil) discharged from the reactor The fractionation operation can be performed online without heating energy using the sensible heat of steam.

  In one embodiment of the invention, the reflux part is a straight connecting pipe, the high-temperature fractionating tower is installed above the reactor, an upper opening of the reactor, and the high-temperature fraction This is a structure in which the bottom opening of the distillation column is connected by the connecting pipe.

  According to this configuration, since the high-temperature fractionation tower is installed facing the upper side of the reactor, the cracked oil gas rises from the reactor and is introduced into the high-temperature fractionation tower. The heavy oil condensed in is naturally moved to the lower reactor by its own weight. Further, the entire installation area can be reduced, and the gas introduction line and the reflux line for introducing gas from the reactor to the high-temperature fractionation tower can be made the same structure, so that the overall structure can be simplified.

Moreover, in one embodiment of the invention described above, it has a gas introduction line that connects the upper opening of the reactor and the lower opening of the high temperature fractionating column,
Unlike the gas introduction line, the reflux part has a reflux line that connects a bottom opening of the high-temperature fractionating column and an upper side opening of the reactor.

  According to this configuration, the cracked oil gas exiting the reactor is introduced into the high-temperature fractionation tower through a gas introduction line (for example, piping), while the heavy oil condensed in the high-temperature fractionation tower is separated. And return to the reactor through the reflux line (eg, piping).

  Moreover, in one Embodiment of the said invention, the said reflux line has a collection | recovery part for collect | recovering the said heavy oil (heavy fraction). The recovery unit includes, for example, a discharge valve, a discharge pipe, and a recovery tank installed in the reflux line.

  According to this configuration, heavy oil can be recovered together with the reflux line, and if necessary, heavy oil can be recovered for use as a heat source for the preheater and the reactor, and light oil can be recovered using the reflux line. It is preferable because the system can be used in a switchable manner with a reflux treatment for improving the yield of high quality cracked oil.

  In one embodiment of the invention, the reflux line has a seal structure that prevents a backflow of gas from the reactor to the high-temperature fractionating tower.

  According to this configuration, it is preferable that no gas is introduced from the reactor into the high-temperature fractionating column through the reflux line. Examples of the sealing structure include a mechanical structure such as a valve and a structure that seals with heavy oil itself (for example, a drain trap structure).

Further, in one embodiment of the present invention, further comprising a reformer that is disposed between the reactor and the high temperature fractionating tower and reforms the cracked oil obtained in the reactor,
The cracked oil reformed by the reformer is introduced into the high temperature fractionating tower.

  According to this configuration, the cracked oil can be modified by, for example, an organic acid decomposition reaction, a cracked oil hydrogenation reaction, or the like. When a reformer is installed, there is a concern that gas flows from the reactor to the high-temperature fractionation tower through the reflux line due to the pressure loss of the reformer, and in order to prevent this, the seal structure described above is used. Is preferably provided.

In addition, the other light oil production method of the present invention,
A filtration step of filtering the raw material oil;
A preheating step of preheating the raw material oil filtered in the filtration step;
A catalytic reaction step in which the raw oil preheated in the preheating step is brought into contact with a fixed catalyst and converted into cracked oil comprising hydrocarbons;
From the cracked oil obtained in the catalytic reaction step, a high-temperature fractionation step of condensing heavy oil and sending hydrocarbon oil other than the condensed heavy oil in a gas state to the subsequent stage;
A refluxing step for refluxing the heavy oil condensed and separated in the high-temperature fractionation step to the reaction step;
Low temperature fractionation that condenses light oil cracked oil from the gaseous hydrocarbon oil sent from the high temperature fractionation step and discharges naphtha gas components other than the condensed light oil cracked oil to the subsequent stage. Process,
A cooling step of cooling the light oily cracked oil (light oil fraction) condensed (fractionated) in the low temperature fractionating tower;
A light oil recovery step of recovering light oil obtained by cooling in the cooling step.

  Moreover, in one Embodiment of the said invention, the process using the said naphtha gas component discharged | emitted from the said low temperature fractionation process as a heat source of the said preheating process is further included.

  Moreover, in one embodiment of the invention described above, a reforming step for reforming the cracked oil obtained in the reaction step, which is a step performed between the reaction step and the high temperature fractionation step, Further, the cracked oil modified and modified in the reforming step is introduced into the high temperature fractionation step.

It is a figure for demonstrating an example of the light oil manufacturing system of Embodiment 1. FIG. FIG. 3 is a diagram for explaining a reflux unit according to the first embodiment. It is a figure for demonstrating an example of the light oil manufacturing system of Embodiment 2. FIG. FIG. 6 is a diagram for explaining a reflux unit according to a second embodiment. It is a figure for demonstrating the recirculation | reflux part of Embodiment 3. FIG. It is a figure for demonstrating the recirculation | reflux part of Embodiment 4. FIG.

(Embodiment 1)
An example of a light oil production system according to Embodiment 1 will be described with reference to FIGS. The light oil production system is made by contacting a raw material tank 1 that stores raw material oil, a filter 2 that filters the raw material oil, a preheater 3 that preheats the raw material oil, and a raw material oil preheated by the preheater 3 into carbonization. A heavy oil (heavy fraction) is condensed from the cracked oil obtained in the reactor 5 having the solid catalyst 51 to be converted into cracked oil composed of hydrogen and the reactor 5, and other than the condensed heavy oil High-temperature fractionation tower 6 for sending the hydrocarbon oil of the gas to the subsequent stage in gas state, a reflux section (L1) for refluxing the heavy oil condensed and separated in the high-temperature fractionation tower 6 to the reactor 5, and high-temperature fractionation Gas oil-derived cracked oil (gas oil fraction) is condensed from the gaseous hydrocarbon oil sent from the tower 6, and naphtha gas components other than the condensed gas oil-based cracked oil (light oil fraction) are downstream. The low-temperature fractionation tower 7 discharged to the bottom, and the light oil cracked oil (light oil fraction) condensed (fractionation) in the low-temperature fractionation tower 7 is cooled. Having a cooling tower 8, and a gas oil recovery unit 9 for recovering the gas oil obtained by cooling in the cooling tower 8.

  A pump P1 for feeding the raw material oil from the raw material tank 1 to the filter 2 and the preheater 3 is further provided. First, impurities are removed from the feedstock oil by the filter 2. Subsequently, the filtered raw material oil is heated to a temperature range of 200 ° C. to 400 ° C. by the preheater 3, and the raw material oil is sprayed and supplied from the upper part of the reactor 5 to the lower solid catalyst 51. The sprayed raw material oil comes into contact with the solid catalyst 51 and is continuously converted into cracked oil, which is a hydrocarbon mixture mainly composed of carbon 9-20 olefins and paraffins. The cracked oil G1 is introduced into the subsequent high-temperature fractionating tower 6 in a gas state through the connecting pipe L1. At this time, the temperature of the cracked oil G <b> 1 in the gas state exiting from the reactor 5 is, for example, 380 ° C. to 400 ° C.

  In the high-temperature fractionation tower 6, heavy oil (heavy fraction) is condensed from cracked oil, and other gas components, hydrocarbon oil G2 (hydrocarbon oil vapor) such as naphtha, kerosene, and light oil are in a gas state. And is introduced into the low-temperature fractionation tower 7. The gas temperature of the hydrocarbon oil G2 exiting from the high temperature fractionating tower 6 is, for example, 250 ° C to 300 ° C.

  In the low-temperature fractionation tower 7, the light oily cracked oil (light oil fraction) is condensed and separated from the hydrocarbon oil, and the diesel oil cooled by the cooling tower 8 is recovered by the diesel oil recovery unit 9. Here, the light oil recovery unit 9 is a recovery tank.

  In addition, components such as naphtha, gas, and kerosene separated by the low-temperature fractionating tower 7 are discharged in a gas state, supplied to the preheater 3 through the gas supply line L5 (for example, piping), and used as a heat source. . Components such as naphtha, gas, and kerosene may use not only sensible heat but also burn components such as naphtha, gas, and kerosene and use the heat. The temperature of components such as naphtha, gas, and kerosene that have come out of the low-temperature fractionation tower 7 is 150 ° C. to 200 ° C., for example. Note that this gas may be used as a heat source of the heat exchanger of the reactor 5.

  In the present embodiment, as shown in FIG. 2, a high-temperature fractionation tower 6 is disposed directly above the reactor 5, and an upper opening 53 of the reactor 5 and a bottom opening of the high-temperature fractionation tower 6 are disposed. 61 is connected by a linear connecting pipe L1 (reflux part). That is, the reflux portion also serves as the connecting pipe L1. The heavy oil (heavy fraction) H1 fractionated in the high-temperature fractionation tower 6 naturally flows downward by its own weight and returns to the reactor 5 (refluxed). The heavy oil (heavy fraction) reacts again with the solid catalyst 51 in the reactor 5 and is decomposed into naphtha, kerosene, and light oil. This improves the yield of light oil as a whole system.

  Here, the structure of the high-temperature fractionating column 6 will be described with reference to FIG. In FIG. 2, a high-temperature fractionating column 6 includes a bottom opening 61 serving as an inlet for cracked oil from the reactor 5, a punching metal 63 receiving the filler 64 below, and a packing for improving gas-liquid contact. It has the material 64, the demister 65 which capture | acquires the mist and fumes contained in hydrocarbon oil vapor | steam, and the upper discharge part 62 for discharging | emitting hydrocarbon oil vapor | steam. Further, a heater 66 is disposed on the side of the tower, and the measurement control unit 68 measures the temperature of the gas discharged from the upper discharge unit 62 and outputs the temperature output of the heater 66 so that the temperature value becomes a constant value. Control.

  The filler 64 preferably has no activity such as ceramic, for example, a ceramic ball, a ceramic crash ring, or the like. Moreover, the magnitude | size and filling amount are set based on the pressure loss of an installation, etc. Note that the structure of the high-temperature fractionating column 6 is not limited to this. Further, the structure of the low temperature fractionation tower 7 can be configured in the same manner as the high temperature fractionation tower 6.

(Embodiment 2)
The embodiment 2 shown in FIGS. 3 and 4 has a gas introduction line L31 that connects the upper opening 53 of the reactor 5 and the lower opening 611 of the high-temperature fractionating column 6, and the reflux part is a gas introduction line. Unlike L31 (for example, piping), it has a configuration having a reflux line L32 (for example, piping) that connects the bottom opening 61 of the high temperature fractionating column 6 and the upper side opening 54 of the reactor 5. In addition, since the structure of the same code | symbol has the same function as Embodiment 1, description is abbreviate | omitted.

  In FIG. 4, cracked oil G <b> 1 (hydrocarbon oil vapor) is introduced into the high temperature fractionating tower 6 through the gas introduction line L <b> 31. The heavy oil (heavy fraction) H1 fractionated in the high-temperature fractionation tower 6 naturally flows downward by its own weight and returns to the reactor 5 (refluxed). The heavy oil (heavy fraction) reacts again with the solid catalyst 51 in the reactor 5 and is decomposed into naphtha, kerosene, and light oil. This improves the yield of light oil as a whole system.

(Embodiment 3)
Embodiment 3 shown in FIG. 5 further includes a reformer 501 that is disposed between the reactor 5 and the high-temperature fractionating tower 6 and reforms the cracked oil G1 obtained in the reactor 5. The cracked oil G1 reformed by the reformer 501 is introduced into the high temperature fractionating tower 6. The reformer 501 has a function of reforming the cracked oil G1 generated by the reactor 5 by, for example, an organic acid decomposition reaction or a cracked oil hydrogenation reaction according to the purpose of reforming.

  The reflux line L32 has a seal structure that prevents the backflow of gas from the reactor 5 to the high temperature fractionating column 6. The seal structure shown in FIG. 5 includes an inner cylinder 102 connected to the bottom opening 61 of the high-temperature fractionating column 6 and an outer cylinder 101 into which the inner cylinder 102 is inserted and arranged. A pipe 101 a provided at the upper part of the outer cylinder 101 is connected to the upper side opening 54 of the reactor 5. The heavy oil H <b> 1 passes through the inner cylinder 102 by its own weight and accumulates in the lower part of the outer cylinder 101, thereby preventing the gas from flowing back from the reactor 5. The reflux oil is accumulated from the inner bottom of the outer cylinder 101 to the pipe 101a, and the overflowed portion returns to the reactor 5.

(Embodiment 4)
Embodiment 4 shown in FIG. 6 has an S-shaped drain trap structure 201 as a seal structure for preventing a backflow of gas from the reactor 5 to the high-temperature fractionating tower 6 in the reflux line L32. The reflux oil (heavy oil) accumulated in the trap unit 202 is sealed against the backflow of gas. The height of the trap unit 202 can be set based on the pressure difference between the reactor 5 and the high temperature fractionating tower 6. The reflux oil accumulates in the trap portion 202, and the overflowed portion returns to the reactor 5.

(Another embodiment)
The reflux line L32 may have a recovery unit (discharge valve, recovery tank, etc.) for recovering heavy oil (heavy fraction).

(Other components)
The heating source of the preheater 3 may be realized by, for example, an electric heater, a burner, or a heat exchanger using hot air, steam, waste gas waste heat, or the like.

  Moreover, it is preferable that the reactor 5 is provided with a heating means for setting the internal temperature and the temperature of the solid catalyst 51 to a catalytic reaction temperature range (for example, 400 to 450 ° C.). The heating means is not particularly limited, and examples thereof include an electric heater, a burner, or a heat exchanger using hot air, steam, waste gas waste heat, and the like. Moreover, it is preferable to use inert gas, such as nitrogen gas, water vapor | steam, offgas, etc. as carrier gas for conveying the cracked oil generate | occur | produced in the reactor 5 to a back | latter stage. This carrier gas may be supplied continuously during operation, or may be supplied according to the operation status.

  In addition, the regeneration of the fixed catalyst 51 can be performed. For regeneration of the solid catalyst, a part of the combustion exhaust gas obtained by burning naphtha, combustible gas or the like in a combustor may be used. The local excessive combustion exceeding the heat resistance temperature of the solid catalyst can be suppressed, and the solid catalyst 51 can be effectively regenerated as a whole. In addition, it is desirable that combustion exhaust gas be combustion controlled in the combustor so that the oxygen concentration is in the range of 1 to 10%, preferably 5 to 10%. The temperature of the combustion exhaust gas is supplied to the reactor 5 in the range of 200 to 500 ° C., preferably 200 to 300 ° C. so that the combustion of coke adhering to the catalyst can be maintained and the catalyst is not overheated. It is desirable to do.

(Production method)
The light oil production method of the present invention will be described below. This manufacturing method is suitably executed in the manufacturing system of the first to fourth embodiments. This production method includes a filtration step of filtering raw material oil,
A preheating step for preheating the raw material oil filtered in the filtration step, a catalytic reaction step for bringing the raw material oil preheated in the preheating step into contact with a fixed catalyst, and converting it into a cracked oil comprising hydrocarbons, and From the cracked oil obtained in the catalytic reaction step, a heavy oil is condensed, and a hydrocarbon oil other than the condensed heavy oil is sent in a gas state to the subsequent stage, and in the high temperature fractionation step, The heavy oil separated by condensation is refluxed to the reaction step, and the light oily cracked oil is condensed from the gaseous hydrocarbon oil sent from the high-temperature fractionation step, Low temperature fractionation process that discharges naphtha gas components other than condensed light oil cracked oil to the subsequent stage, and cools light oil cracked oil (light oil fraction) condensed (fractionated) in the low temperature fractionation tower And recovering light oil obtained by cooling in the cooling process That and a light oil recovery process.

  The method further includes a step of using the naphtha gas component discharged from the low temperature fractionation step as a heat source for the preheating step.

  The method further includes a reforming step that is performed between the reaction step and the high-temperature fractionation step and reforms the cracked oil obtained in the reaction step, and is modified in the reforming step. The refined cracked oil is introduced into the high temperature fractionation process.

<Example>
Using the system of FIGS. 3 and 4 described above, light oil was produced using waste cooking oil as a production raw material. As an example, heavy oil agglomerated in a high-temperature fractionation tower (fractionation loss, fractionation residue) was refluxed to the reactor. As a comparative example, the heavy oil was recovered as it was without refluxing.

Salad oil after 1 week of use was used as waste cooking oil. In this example, light oil was produced at a processing speed of 12.5 L / h with respect to 100 L of waste cooking oil. As a solid _catalyst, using a supported catalyst of SiO 2 -MgO _(which is configured with a supported metal oxides of SiO 2 -MgO).

  First, foreign substances were removed from the waste cooking oil using a 1 μ filter. Subsequently, it heated to about 400 degreeC with the preheater, and obtained the raw material liquid (it is in the state which is not vaporized). Next, the preheated raw material liquid was sprayed into the reactor of the fixed catalyst and contacted with the solid catalyst to obtain cracked oil gas. In addition, cracked gas, residue, coke, etc. are generated.

  The cracked oil gas generated in the reactor is introduced into a high-temperature fractionating column. This cracked oil gas was subjected to fractional distillation at 350 ° C. in a high-temperature fractionation tower, and fractional distillation was continuously carried out at 120 to 150 ° C. in a low-temperature fractionation tower. That is, hydrocarbon oils such as gas components, naphtha (liquid), kerosene (liquid), light oil (liquid), residual fraction, and coke were continuously fractionated.

  At this time, the composition and mass of the components produced at each stage were analyzed, and the weight balance was calculated. The results are shown in Table 1. Here, from the high-temperature fractionation tower, a fractionation loss of about 5% and a fractionation residue of about 2% occurred as heavy oil. In the examples, this heavy oil was refluxed to the reactor to obtain cracked oil again. Table 2 shows the weight yield for obtaining light oil from heavy oil. From the results of Tables 1 and 2, in the system that did not recirculate heavy oil (comparative example), the weight yield of light oil was 70%, but in the system that recirculated heavy oil (Example), Was 4.9% higher (74.9%) than that.

DESCRIPTION OF SYMBOLS 1 Raw material oil tank 2 Filter 3 Preheater 5 Reactor 6 High temperature fractionator 7 Low temperature fractionator 8 Cooling tower 9 Light oil recovery part 51 Solid catalyst

Claims (10)

A raw material tank for storing raw material oil;
A filter for filtering the raw oil;
A preheater for preheating the raw oil filtered by the filter;
A reactor having a solid catalyst that contacts the feed oil preheated by the preheater and converts it into cracked oil comprising hydrocarbons;
A high-temperature fractionating tower that condenses heavy oil (heavy fraction) from the cracked oil obtained in the reactor and sends hydrocarbon oil other than the condensed heavy oil in a gaseous state to the subsequent stage;
A reflux section for refluxing the heavy oil condensed and separated in the high-temperature fractionating column to the reactor;
Gas oil cracked oil (light oil fraction) is condensed from the gaseous hydrocarbon oil sent from the high temperature fractionating tower, and naphtha gas components other than the condensed light oil cracked oil are passed to the subsequent stage. A low-temperature fractionating tower to be discharged;
A cooling tower that cools the light oily cracked oil (light oil fraction) condensed (fractionated) in the low-temperature fractionating tower;
A light oil recovery system that recovers light oil obtained by cooling in the cooling tower.   The light oil production system according to claim 1, further comprising a supply line that supplies the naphtha gas component discharged from the low-temperature fractionating tower to the preheater and uses it as a heat source. The reflux part is a straight connecting pipe;
The high temperature fractionating tower is installed above the reactor,
The light oil production system according to claim 1 or 2, wherein a top opening of the reactor and a bottom opening of the high temperature fractionating column are connected by the connecting pipe. A gas introduction line connecting the upper opening of the reactor and the lower opening of the high-temperature fractionating column;
The reflux part is
The gas oil production system according to claim 1, further comprising a reflux line that connects a bottom opening of the high-temperature fractionating column and an upper side opening of the reactor, unlike the gas introduction line.   The light oil production system according to claim 4, wherein the reflux line includes a recovery unit for recovering the heavy oil (heavy fraction).   6. The light oil production system according to claim 4, wherein the reflux line has a seal structure that prevents backflow of gas from the reactor to the high-temperature fractionation tower. A reformer that is disposed between the reactor and the high-temperature fractionation tower and reforms the cracked oil obtained in the reactor;
The light oil production system according to any one of claims 4 to 6, wherein the cracked oil reformed by the reformer is introduced into the high temperature fractionating tower. A filtration step of filtering the raw material oil;
A preheating step of preheating the raw material oil filtered in the filtration step;
A catalytic reaction step in which the raw oil preheated in the preheating step is brought into contact with a fixed catalyst and converted into cracked oil comprising hydrocarbons;
From the cracked oil obtained in the catalytic reaction step, a high-temperature fractionation step of condensing heavy oil and sending hydrocarbon oil other than the condensed heavy oil in a gas state to the subsequent stage;
A refluxing step for refluxing the heavy oil condensed and separated in the high-temperature fractionation step to the reaction step;
Low temperature fractionation that condenses light oil cracked oil from the gaseous hydrocarbon oil sent from the high temperature fractionation step and discharges naphtha gas components other than the condensed light oil cracked oil to the subsequent stage. Process,
A cooling step of cooling the light oily cracked oil (light oil fraction) condensed (fractionated) in the low temperature fractionating tower;
A light oil recovery step of recovering light oil obtained by cooling in the cooling step.   The light oil production method according to claim 8, further comprising a step of using the naphtha gas component discharged from the low temperature fractionation step as a heat source of the preheating step. A step performed between the reaction step and the high temperature fractionation step, further comprising a reforming step of reforming the cracked oil obtained in the reaction step;
The method for producing diesel oil according to claim 8 or 9, wherein the cracked oil modified in the reforming step is introduced into the high-temperature fractionating step.

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