JP5107234B2 - Liquid fuel synthesis system - Google Patents

Description

The present invention relates to a liquid fuel synthesis system.

This application claims priority about the Japan patent application 2006-95516 for which it applied on March 30, 2006, and uses the content here.

In recent years, as one of the methods for synthesizing liquid fuel from natural gas, the natural gas is reformed to produce a synthetic gas mainly composed of carbon monoxide gas (CO) and hydrogen gas (H ₂ ), By synthesizing liquid hydrocarbons by Fischer-Tropsch synthesis reaction (hereinafter referred to as “FT synthesis reaction”) using this synthesis gas as raw material gas, and further hydrogenating and purifying this liquid hydrocarbon, naphtha (crude gasoline) GTL (Gas To Liquid) technology for producing liquid fuel products such as kerosene, light oil and wax has been developed.

In such a liquid fuel synthesis system using GTL technology, an oily intermediate product produced by the FT synthesis reaction is introduced into a rectification tower on the downstream side of the liquid fuel synthesis system at a predetermined temperature ( For example, it is necessary to heat to about 320 ° C.
In addition, the intermediate product separated for each boiling point by this rectification column is further hydrogenated and refined in a hydrogenation reactor to become a product, but before being introduced into this hydrogenation reactor. However, it is necessary to heat the separated intermediate product to a predetermined temperature range (for example, 100 to 400 ° C.).

  In a conventional liquid fuel synthesis system using GTL technology, heat medium oil is used as a heating medium in order to perform heating to the above temperature range.

  However, in order to use the heat medium oil as a heating medium, it is necessary to install a device for storing the heat medium oil, a device for heating the heat medium oil, or the like in the liquid fuel synthesis system. . Further, the heat utilization efficiency of the entire liquid fuel synthesis system is not improved.

  The present invention has been made in view of such problems, and an object of the present invention is to provide a liquid fuel synthesis system capable of improving the thermal efficiency of the entire liquid fuel synthesis system.

The liquid fuel synthesizing system of the present invention includes a reformer that reforms a hydrocarbon raw material to generate a syngas mainly composed of carbon monoxide gas and hydrogen gas; and is provided in the reformer for supply A burner that burns the generated fuel gas and discharges the exhaust gas; a reactor that synthesizes liquid hydrocarbons from carbon monoxide gas and hydrogen gas contained in the synthesis gas; and a liquid hydrocarbon that is synthesized in the reactor And a heating means for heating the liquid hydrocarbon introduced into the purification processing apparatus using the exhaust gas discharged from a burner provided in the reformer as a heat source. Comprising.

According to the liquid fuel synthesizing system of the present invention, the reformer reforms the hydrocarbon raw material to generate a syngas mainly composed of carbon monoxide gas and hydrogen gas, and the reactor uses the syngas as a raw material. The liquid fuel is synthesized, the refining apparatus performs a predetermined refining process on the mixture of the plurality of types of liquid fuel, and the heating unit heats the liquid fuel introduced into the refining apparatus. By supplying the high-temperature exhaust gas discharged from the burner provided in the reformer to the heating means, this high-temperature exhaust gas can be directly used as a heating medium. As a result, it is possible to improve the thermal efficiency of the entire liquid fuel synthesis system.

  In the liquid fuel synthesizing system of the present invention, the refining apparatus includes a rectifying tower for fractionating the liquid hydrocarbon into a plurality of types of liquid fuels having different boiling points, or a hydrogenation reactor for hydrogenating the liquid hydrocarbon. It may be at least one of the above.

The heating means may be a heat exchanger capable of exchanging heat between gas and liquid, for example.
Further, the liquid fuel synthesized in the reactor may be a mixture of a plurality of types of liquid fuels having different boiling points.

According to the present invention, the thermal efficiency of the entire liquid fuel synthesis system can be improved by using the exhaust gas discharged from the burner provided in the reformer as a heat source.

FIG. 1 is a schematic diagram showing the overall configuration of a liquid fuel synthesis system according to an embodiment of the present invention. FIG. 2 is a block diagram showing heating means of the liquid fuel synthesis system according to the embodiment of the present invention.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Liquid fuel synthesis system, 3 ... Syngas production unit, 5 ... FT synthesis unit, 7 ... Product refinement unit, 9 ... Purification processing apparatus, 10 ... Desulfurization reactor, 12 ... Reformer, 14 ... Exhaust heat boiler, 16, 18 ... Gas-liquid separator, 20 ... Decarbonation device, 22 ... Absorption tower, 24 ... Regeneration tower, 26 ... Hydrogen separation device, 30 ... Bubble column reactor, 32 ... Heat transfer tube, 34, 38 ... Gas-liquid Separator, 36 ... Separator, 40 ... First fractionator, 50 ... WAX fraction hydrocracking reactor, 52 ... Kerosene / light oil fraction hydrotreating reactor, 54 ... Naphtha fraction hydrotreating reactor, 56, 58, 60 ... Gas-liquid separator, 70 ... Second fractionator, 72 ... Naphtha stabilizer, 100, 102, 104 ... Heat exchanger

  Exemplary embodiments of the present invention will be described below in detail with reference to the accompanying drawings. In addition, in this specification and drawing, about the component which has the substantially same function structure, duplication description is abbreviate | omitted by attaching | subjecting the same code | symbol.

  First, an overall configuration and operation of a liquid fuel synthesizing system 1 that executes a GTL (Gas To Liquid) process according to an embodiment of the present invention will be described with reference to FIG. FIG. 1 is a schematic diagram showing the overall configuration of a liquid fuel synthesis system 1 according to the present embodiment.

  As shown in FIG. 1, a liquid fuel synthesis system 1 according to the present embodiment is a plant facility that executes a GTL process for converting a hydrocarbon raw material such as natural gas into liquid fuel. The liquid fuel synthesis system 1 includes a synthesis gas generation unit 3, an FT synthesis unit 5, and a product purification unit 7. The synthesis gas generation unit 3 reforms natural gas that is a hydrocarbon raw material to generate synthesis gas containing carbon monoxide gas and hydrogen gas. The FT synthesis unit 5 generates liquid hydrocarbons from the synthesis gas by a Fischer-Tropsch synthesis reaction (hereinafter referred to as “FT synthesis reaction”). The product refining unit 7 produces liquid fuel products (naphtha, kerosene, light oil, wax, etc.) by hydrogenating and refining the liquid hydrocarbons produced by this FT synthesis reaction. Hereinafter, components of each unit will be described.

First, the synthesis gas generation unit 3 will be described. The synthesis gas generation unit 3 mainly includes, for example, a desulfurization reactor 10, a reformer 12, an exhaust heat boiler 14, gas-liquid separators 16 and 18, a decarboxylation device 20, and a hydrogen separation device 26. Prepare. The desulfurization reactor 10 is composed of a hydrodesulfurization device or the like and removes sulfur components from natural gas as a raw material. The reformer 12 reforms the natural gas supplied from the desulfurization reactor 10 to generate a synthesis gas containing carbon monoxide gas (CO) and hydrogen gas (H ₂ ) as main components. The exhaust heat boiler 14 recovers the exhaust heat of the synthesis gas generated in the reformer 12 and generates high-pressure steam. The gas-liquid separator 16 separates water heated by heat exchange with the synthesis gas in the exhaust heat boiler 14 into a gas (high-pressure steam) and a liquid. The gas-liquid separator 18 removes the condensate from the synthesis gas cooled by the exhaust heat boiler 14 and supplies the gas to the decarboxylation device 20. The decarbonation device 20 removes carbon dioxide from the synthesis gas supplied from the gas-liquid separator 18 using the absorbent, and strips the carbon dioxide from the absorbent containing the carbon dioxide to release it. And a regeneration tower 24 for regeneration. The hydrogen separation device 26 separates a part of the hydrogen gas contained in the synthesis gas from the synthesis gas from which the carbon dioxide gas has been separated by the decarbonation device 20.

  Among these, the reformer 12 reforms natural gas using carbon dioxide and steam by, for example, the steam / carbon dioxide reforming method represented by the following chemical reaction formulas (1) and (2). Thus, a high-temperature synthesis gas mainly composed of carbon monoxide gas and hydrogen gas is generated. The reforming method in the reformer 12 is not limited to the steam / carbon dioxide reforming method described above, but includes, for example, a steam reforming method, a partial oxidation reforming method (POX) using oxygen, and a partial oxidation method. An autothermal reforming method (ATR), a carbon dioxide gas reforming method, or the like, which is a combination of the reforming method and the steam reforming method, can also be used.

CH ₄ + H ₂ O → CO + 3H ₂ (1)
CH ₄ + CO ₂ → 2CO + 2H ₂ (2)

  The hydrogen separator 26 is provided on a branch line branched from a main pipe connecting the decarbonator 20 or the gas-liquid separator 18 and the bubble column reactor 30. The hydrogen separator 26 can be constituted by, for example, a hydrogen PSA (Pressure Swing Adsorption) device that performs adsorption and desorption of hydrogen using a pressure difference. This hydrogen PSA apparatus has an adsorbent (zeolite adsorbent, activated carbon, alumina, silica gel, etc.) in a plurality of adsorption towers (not shown) arranged in parallel, and pressurizes in each adsorption tower. By repeating the steps of adsorption, desorption (decompression), and purge in order, the purity of the hydrogen gas can be increased (for example, about 99.999%) and continuously supplied to the reactor.

  Note that the hydrogen gas separation method in the hydrogen separator 26 is not limited to the pressure fluctuation adsorption method such as the hydrogen PSA device described above, and for example, a hydrogen storage alloy adsorption method, a membrane separation method, or a combination thereof. There may be.

The hydrogen storage alloy method is, for example, a hydrogen storage alloy having a property of adsorbing / releasing hydrogen by being cooled / heated (TiFe, LaNi ₅ , TiFe _{0.7 to 0.9} , Mn _{0.3 to 0.1).} Or TiMn _1.5 or the like) to separate hydrogen gas. A plurality of adsorption towers containing hydrogen storage alloys are provided, and in each of the adsorption towers, hydrogen adsorption by cooling the hydrogen storage alloys and hydrogen release by heating the hydrogen storage alloys are alternately repeated, so that the inside of the synthesis gas Of hydrogen gas can be separated and recovered.

  The membrane separation method is a method of separating hydrogen gas having excellent membrane permeability from a mixed gas using a membrane made of a polymer material such as aromatic polyimide. Since this membrane separation method does not involve a phase change, the energy required for operation is small, and the running cost is low. Further, since the structure of the membrane separation apparatus is simple and compact, the equipment cost is low and the required area of the equipment is small. Further, the separation membrane has no driving device and has a wide stable operation range, so that there is an advantage that maintenance management is easy.

  Next, the FT synthesis unit 5 will be described. The FT synthesis unit 5 mainly includes, for example, a bubble column reactor 30, a gas-liquid separator 34, a separator 36, a gas-liquid separator 38, and a first rectifying column 40. The bubble column reactor 30 generates a liquid hydrocarbon by performing an FT synthesis reaction of the synthesis gas produced by the synthesis gas production unit 3, that is, carbon monoxide gas and hydrogen gas. The gas-liquid separator 34 separates water heated through circulation in the heat transfer tube 32 disposed in the bubble column reactor 30 into water vapor (medium pressure steam) and liquid. The separator 36 is connected to the center of the bubble column reactor 30 and separates the catalyst and the liquid hydrocarbon product. The gas-liquid separator 38 is connected to the upper part of the bubble column reactor 30 and cools the unreacted synthesis gas and the gaseous hydrocarbon product. The first fractionator 40 distills the liquid hydrocarbons supplied from the bubble column reactor 30 via the separator 36 and the gas-liquid separator 38, and separates and purifies each product fraction according to the boiling point. .

  Among these, the bubble column reactor 30 is an example of a reactor that synthesizes synthesis gas into liquid hydrocarbons, and functions as a reactor for FT synthesis that synthesizes liquid hydrocarbons from synthesis gas by an FT synthesis reaction. The bubble column reactor 30 is constituted by, for example, a bubble column type slurry bed type reactor in which a slurry composed of a catalyst and a medium oil is stored inside a column type container. The bubble column reactor 30 generates liquid hydrocarbons from synthesis gas by an FT synthesis reaction. Specifically, in this bubble column reactor 30, the synthesis gas, which is a raw material gas, is supplied as bubbles from the dispersion plate at the bottom of the bubble column reactor 30, and passes through the slurry composed of catalyst and medium oil. Then, as shown in the chemical reaction formula (3) below, the hydrogen gas and the carbon monoxide gas cause a synthesis reaction in the suspended state.

2nH ₂ + nCO → − (CH ₂ ) _n − + nH ₂ O (3)

  Since this FT synthesis reaction is an exothermic reaction, the bubble column reactor 30 is a heat exchanger type in which a heat transfer tube 32 is disposed, and for example, water (BFW: Boiler Feed Water) is used as a refrigerant. Then, the reaction heat of the FT synthesis reaction can be recovered as medium pressure steam by heat exchange between the slurry and water.

  Finally, the product purification unit 7 will be described. The product refining unit 7 includes, for example, a WAX fraction hydrocracking reactor 50, a kerosene / light oil fraction hydrotreating reactor 52, a naphtha fraction hydrotreating reactor 54, and gas-liquid separators 56, 58, 60, a second rectifying column 70, and a naphtha stabilizer 72. The WAX fraction hydrocracking reactor 50 is connected to the lower part of the first fractionator 40. The kerosene / light oil fraction hydrotreating reactor 52 is connected to the center of the first fractionator 40. The naphtha fraction hydrotreating reactor 54 is connected to the upper part of the first fractionator 40. The gas-liquid separators 56, 58 and 60 are provided corresponding to the hydrogenation reactors 50, 52 and 54, respectively. The second rectification column 70 separates and purifies the liquid hydrocarbons supplied from the gas-liquid separators 56 and 58 according to the boiling point. The naphtha stabilizer 72 rectifies liquid hydrocarbons of the naphtha fraction supplied from the gas-liquid separator 60 and the second rectifying column 70, and discharges lighter components than butane to the flare gas side, and has 5 or more carbon atoms. The components are separated and recovered as naphtha of the product.

  Next, a process (GTL process) of synthesizing liquid fuel from natural gas by the liquid fuel synthesizing system 1 having the above configuration will be described.

The liquid fuel synthesis system 1 is supplied with natural gas (main component is CH ₄ ) as a hydrocarbon feedstock from an external natural gas supply source (not shown) such as a natural gas field or a natural gas plant. The synthesis gas generation unit 3 reforms the natural gas to produce a synthesis gas (a mixed gas containing carbon monoxide gas and hydrogen gas as main components).

  Specifically, first, the natural gas is supplied to the desulfurization reactor 10 together with the hydrogen gas separated by the hydrogen separator 26. The desulfurization reactor 10 hydrodesulfurizes sulfur contained in natural gas using the hydrogen gas, for example, with a ZnO catalyst. By previously desulfurizing natural gas in this way, it is possible to prevent the activity of the catalyst used in the reformer 12 and the bubble column reactor 30 or the like from being reduced by sulfur.

The natural gas (which may contain carbon dioxide) desulfurized in this way is generated in carbon dioxide (CO ₂ ) gas supplied from a carbon dioxide supply source (not shown) and the exhaust heat boiler 14. After being mixed with water vapor, it is supplied to the reformer 12. For example, the reformer 12 reforms the natural gas using carbon dioxide and steam by the steam / carbon dioxide reforming method described above, so that the reformer 12 has a high temperature mainly composed of carbon monoxide gas and hydrogen gas. Generate synthesis gas. At this time, for example, fuel gas and air for a burner provided in the reformer 12 are supplied to the reformer 12, and the steam / carbon dioxide reforming reaction is performed by the combustion heat of the fuel gas in the burner. Necessary heat of reaction is covered. The liquid fuel synthesizing system 1 according to this embodiment is characterized in that it uses an exhaust gas of about 1000 to 1200 ° C. generated by the combustion heat of the combustion gas in this burner. This point will be described in detail below.

  The high-temperature synthesis gas (for example, 900 ° C., 2.0 MPaG) generated in the reformer 12 in this manner is supplied to the exhaust heat boiler 14 and is exchanged by heat exchange with the water flowing in the exhaust heat boiler 14. It is cooled (for example, 400 ° C.) and the exhaust heat is recovered. At this time, water heated by the synthesis gas in the exhaust heat boiler 14 is supplied to the gas-liquid separator 16, and the gas component is reformed as high-pressure steam (for example, 3.4 to 10.0 MPaG) from the gas-liquid separator 16. The water in the liquid is returned to the exhaust heat boiler 14 after being supplied to the vessel 12 or other external device.

  On the other hand, the synthesis gas cooled in the exhaust heat boiler 14 is supplied to the absorption tower 22 or the bubble column reactor 30 of the decarboxylation device 20 after the condensed liquid is separated and removed in the gas-liquid separator 18. The The absorption tower 22 removes carbon dioxide from the synthesis gas by absorbing the carbon dioxide contained in the synthesis gas in the stored absorption liquid. The absorption liquid containing carbon dioxide gas in the absorption tower 22 is sent to the regeneration tower 24, and the absorption liquid containing carbon dioxide gas is heated by, for example, steam and stripped. To the reformer 12 and reused in the reforming reaction.

In this way, the synthesis gas produced by the synthesis gas production unit 3 is supplied to the bubble column reactor 30 of the FT synthesis unit 5. At this time, the composition ratio of the synthesis gas supplied to the bubble column reactor 30 is adjusted to a composition ratio (for example, H ₂ : CO = 2: 1 (molar ratio)) suitable for the FT synthesis reaction. The synthesis gas supplied to the bubble column reactor 30 is subjected to an FT synthesis reaction by a compressor (not shown) provided in a pipe connecting the decarboxylation device 20 and the bubble column reactor 30. The pressure is increased to an appropriate pressure (for example, about 3.6 MPaG).

  A part of the synthesis gas from which the carbon dioxide gas has been separated by the decarbonation device 20 is also supplied to the hydrogen separation device 26. The hydrogen separator 26 separates the hydrogen gas contained in the synthesis gas by adsorption and desorption (hydrogen PSA) using the pressure difference as described above. The separated hydrogen is subjected to various hydrogen utilization reactions in which a predetermined reaction is performed using hydrogen in the liquid fuel synthesizing system 1 from a gas holder (not shown) or the like via a compressor (not shown). It supplies continuously to the apparatus (for example, desulfurization reactor 10, WAX fraction hydrocracking reactor 50, kerosene / light oil fraction hydrotreating reactor 52, naphtha fraction hydrotreating reactor 54, etc.).

  Next, the FT synthesis unit 5 synthesizes liquid hydrocarbons from the synthesis gas produced by the synthesis gas production unit 3 by an FT synthesis reaction.

  Specifically, the synthesis gas from which the carbon dioxide gas has been separated in the decarboxylation device 20 flows from the bottom of the bubble column reactor 30 and rises in the catalyst slurry stored in the bubble column reactor 30. To do. At this time, in the bubble column reactor 30, the carbon monoxide and hydrogen gas contained in the synthesis gas react with each other by the above-described FT synthesis reaction to generate hydrocarbons. Furthermore, at the time of this synthesis reaction, water is circulated through the heat transfer tube 32 of the bubble column reactor 30 to remove the reaction heat of the FT synthesis reaction. Become. As for the water vapor, the water liquefied by the gas-liquid separator 34 is returned to the heat transfer tube 32, and the gas component is supplied to the external device as medium pressure steam (for example, gas pressure 1.0 to 2.5 MPaG).

In this way, the liquid hydrocarbon synthesized in the bubble column reactor 30 is taken out from the center of the bubble column reactor 30 and sent to the separator 36. The separator 36 separates the catalyst (solid content) in the extracted slurry into a liquid content containing the liquid hydrocarbon product. A part of the separated catalyst is returned to the bubble column reactor 30, and the liquid is supplied to the first rectifying column 40. Further, unreacted synthesis gas and synthesized hydrocarbon gas are introduced into the gas-liquid separator 38 from the top of the bubble column reactor 30. The gas-liquid separator 38 cools these gases, separates some of the condensed liquid hydrocarbons, and introduces them into the first fractionator 40. On the other hand, for the gas component separated by the gas-liquid separator 38, the unreacted synthesis gas (CO and H ₂ ) is reintroduced into the bottom of the bubble column reactor 30 and reused in the FT synthesis reaction. Further, exhaust gas mainly composed of hydrocarbon gas having a low carbon number (C ₄ or less), which is not a product object, is generally introduced into an external combustion facility (not shown) as a flare gas and burned. Later released into the atmosphere.

Next, the first rectifying column 40 heats the liquid hydrocarbon (having various carbon numbers) supplied from the bubble column reactor 30 through the separator 36 and the gas-liquid separator 38 as described above. Fractionation using the difference in boiling point, naphtha fraction (boiling point is less than about 315 ° C), kerosene / light oil fraction (boiling point is about 315 to 800 ° C), WAX (boiling point is about 800 ° C or more) Large) and separated and purified. Wax liquid hydrocarbons (mainly C ₂₁ or more) taken out from the bottom of the first fractionator 40 are transferred to the WAX fraction hydrocracking reactor 50 and taken out from the center of the first fractionator 40. The liquid hydrocarbon (mainly C _{11 to} C ₂₀ ) of the kerosene / light oil fraction is transferred to the kerosene / light oil fraction hydrotreating reactor 52 and taken out from the upper part of the first rectifying column 40. Hydrocarbons (mainly C ₅ -C ₁₀ ) are transferred to the naphtha fraction hydrotreating reactor 54.

The WAX fraction hydrocracking reactor 50 is a liquid fed from the lower part of the first rectifying column 40 to a liquid hydrocarbon having a high carbon number (approximately C ₂₁ or more) and hydrogen supplied from the hydrogen separator 26. Hydrocracking using gas to reduce the carbon number to ₂₀ or less. In this hydrocracking reaction, a C—C bond of a hydrocarbon having a large number of carbon atoms is cut using a catalyst and heat to generate a low molecular weight hydrocarbon having a small number of carbon atoms. A product containing liquid hydrocarbons hydrocracked by the WAX hydrocracking reactor 50 is separated into a gas and a liquid by a gas-liquid separator 56, and the liquid hydrocarbons are separated from the second fractionator. The gas component (including hydrogen gas) is transferred to a kerosene / light oil fraction hydrotreating reactor 52 and a naphtha fraction hydrotreating reactor 54.

The kerosene / light oil fraction hydrotreating reactor 52 is a liquid hydrocarbon (generally C _{11 to} C ₂₀ ) of the kerosene / light oil fraction supplied from the center of the first fractionator 40 and having a medium number of carbon atoms. Is hydrorefined using the hydrogen gas supplied from the hydrogen separator 26 via the WAX fraction hydrocracking reactor 50. This hydrorefining reaction is a reaction in which hydrogen is added to the unsaturated bond of the liquid hydrocarbon to saturate to produce a linear saturated hydrocarbon. As a result, the hydrorefined liquid hydrocarbon-containing product is separated into a gas and a liquid by the gas-liquid separator 58, and the liquid hydrocarbon is transferred to the second rectifying column 70, where the gas component (hydrogen Gas is reused) in the hydrogenation reaction.

The naphtha fraction hydrotreating reactor 54, the upper supplied from the naphtha fraction of liquid hydrocarbons having a small number of carbon atoms of the first fractionator 40 (approximately _of C ₁₀ or less), WAX fraction hydrogen from the hydrogen separator 26 Hydrotreating is performed using the hydrogen gas supplied through the hydrocracking reactor 50. As a result, the hydrorefined liquid hydrocarbon-containing product is separated into a gas and a liquid by the gas-liquid separator 60, and the liquid hydrocarbon is transferred to a naphtha stabilizer 72, which is a kind of rectification column. The gas component (including hydrogen gas) is reused in the hydrogenation reaction.

Next, the second rectifying column 70 distills the liquid hydrocarbons supplied from the WAX fraction hydrocracking reactor 50 and the kerosene / light oil fraction hydrotreating reactor 52 as described above to obtain a carbon number. and _of C ₁₀ or less hydrocarbons (having a boiling point of approximately less than 315 ° C.), and kerosene (boiling point of about three hundred fifteen to four hundred fifty ° C.), separated and purified in the gas oil (boiling point of about 450 to 800 ° C.). Light oil is taken out from the lower part of the second fractionator 70, and kerosene is taken out from the center. On the other hand, a hydrocarbon gas having a carbon number of ₁₀ or less is taken out from the top of the second rectifying column 70 and supplied to the naphtha stabilizer 72.

Further, the naphtha stabilizer 72 distills hydrocarbons having a carbon number of ₁₀ or less supplied from the naphtha fraction hydrotreating reactor 54 and the second rectifying tower 70 to obtain naphtha (C ₅ as a product). ~C ₁₀₎ are separated and purified. Thereby, high-purity naphtha is taken out from the lower part of the naphtha stabilizer 72. Meanwhile, from the top of the naphtha stabilizer 72, the exhaust gas carbon number of target products composed mainly of hydrocarbons below predetermined number (C ₄ or less) (flare gas) is discharged. This exhaust gas is sent to an external combustion facility (not shown), burned, and then released into the atmosphere.

The process of the liquid fuel synthesis system 1 (GTL process) has been described above. By such a GTL process, natural gas is cleaned into high purity naphtha (C _{5 to} C ₁₀ : crude gasoline), kerosene (C _{11 to} C ₁₅ : kerosene) and light oil (C _{16 to} C ₂₀ : gas oil). It can be easily and economically converted to liquid fuel. Furthermore, in this embodiment, since the steam / carbon dioxide reforming method is adopted in the reformer 12, carbon dioxide contained in natural gas as a raw material is effectively used, and the FT synthesis is performed. A composition ratio (for example, H ₂ : CO = 2: 1 (molar ratio)) of synthesis gas suitable for the reaction can be efficiently generated by one reaction of the reformer 12, and a hydrogen concentration adjusting device, etc. There is an advantage that is unnecessary.

  Next, the heating means used in the liquid fuel synthesis system according to the present embodiment will be described in detail with reference to FIG. FIG. 2 is a block diagram showing heating means of the liquid fuel synthesis system according to the present embodiment.

  As described above, the reformer 12 according to this embodiment is composed of natural gas and carbon dioxide gas supplied as raw materials, and the main component is carbon monoxide gas and hydrogen gas as high as about 1000 ° C. Although it is an apparatus that generates gas, in order to obtain reaction heat required for the generation reaction of this high-temperature synthesis gas, it is necessary to burn the fuel gas introduced into the reformer 12 with a burner or the like as described above. . Due to the combustion of the fuel gas, exhaust gas of about 1000 to 1200 ° C. is discharged from the reformer 12.

  In a conventional liquid fuel synthesis system using a reformer, natural gas and BFW (Boiler Feed Water) as raw materials are heated by heat exchange with the above-described high-temperature exhaust gas to effectively use waste heat. It was only.

  Therefore, in the liquid fuel synthesizing system according to this embodiment, the high-temperature exhaust gas discharged from the reformer 12 is directly used as a heating medium, and the thermal efficiency of the entire system can be improved as compared with the conventional system. .

  When the mixture of a plurality of types of liquid fuels having different boiling points generated in the bubble column reactor 30 is introduced into the first rectifying column 40 in the FT synthesis unit 5, the temperature of the liquid fuel mixture is set to It is necessary to keep the temperature at about 320 ° C. However, since the temperature of the liquid fuel mixture taken out from the bubble-type reactor 30 is about 240 ° C., it is necessary to heat the mixture to about 80 ° C. to the above temperature. Further, as shown in FIG. 1, the first fractionator 40 is also supplied with a liquid hydrocarbon component of about 40 ° C. separated as a liquid by the gas-liquid separator 38. This liquid hydrocarbon component also needs to be heated to about 320 ° C.

  Therefore, in the liquid fuel synthesizing system according to this embodiment, heating means such as the heat exchanger 100 is provided on the inlet side of the first rectifying tower 40, and the high-temperature exhaust gas discharged from the reformer 12 is directly It was decided to supply.

  As said heat exchanger 100, the heat exchanger which can perform heat exchange between gas-liquids can be used. Examples of such a heat exchanger include, for example, a plate heat exchanger and a finned tube heat exchanger. These heat exchangers are devices that transfer heat between a gas and a liquid via a plate or a tube.

  That is, the liquid fuel mixture produced in the bubble column reactor 30 passes through the heat exchanger 100 provided between the bubble column reactor 30 and the first rectification column 40, and is subjected to the first rectification. Although supplied to the tower 40, the liquid fuel mixture is heated to about 320 ° C. by the high-temperature exhaust gas discharged from the reformer 12 to the heat exchanger 100 when passing through the heat exchanger 100. The exhaust gas from the reformer 12 that has passed through the heat exchanger 100 is discarded after being subjected to a predetermined treatment.

  Thus, the liquid fuel synthesizing system according to the present embodiment uses a high-temperature exhaust gas directly to heat a mixture of a plurality of types of liquid fuels introduced into the first rectifying tower 40. Compared with a heating method using oil, the thermal efficiency can be improved, and there is no need to newly provide equipment or the like for generating heat transfer oil.

  As shown in FIG. 1, the mixture of a plurality of types of liquid fuel is fractionated into three types of liquid fuel by the first fractionator 40 based on the difference in boiling point, and purified. Next, the liquid fuels fractionated into the three types are respectively supplied to the hydrogenation reactors 50, 52, and 54 in the product purification unit 7, where C = C double bonds, C≡C triple bonds, etc. The liquid fuel containing the unsaturated bond is hydrogenated into a liquid fuel having only a C—C single bond. These three types of liquid fuels need to be heated to about 300 ° C. when supplied to the hydrogenation reactors 50, 52, and 54, respectively. Also in this case, in the same manner as described above, for example, a heat exchanger 102 is provided as a heating means between the first rectification column 40 and each of the hydrogenation reactors 50, 52, 54. By supplying the exhaust gas discharged from the reformer 12, each liquid fuel can be efficiently heated.

  As shown in FIG. 1, the hydrogenated liquid fuels are introduced into the second rectifying column 70, where they are separated and purified. Also in this case, each fuel needs to be heated to about 110 to 400 ° C. before being supplied to the second rectification column 70. Also in this case, as shown in FIG. 2, for example, a heat exchanger 104 is provided as a heating means between each hydrogenation reactor 50, 52, 54 and the second rectifying column 70, and this heat By supplying the exhaust gas discharged from the reformer 12 to the exchanger 102, it is possible to efficiently heat the liquid fuel.

  As for the heat exchangers 102 and 104, a heat exchanger similar to the heat exchanger 100 can be used. The exhaust gas from the reformer 12 that has passed through the heat exchangers 102 and 104 is discarded after being subjected to a predetermined treatment.

  FIG. 2 shows the case where the exhaust gas discharged from the reformer 12 is supplied to each heat exchanger 100, 102, 104 using a common exhaust gas supply path. However, the present invention is not limited to such an example. For example, paths dedicated to the heat exchangers 100, 102, and 104 may be provided separately.

  Thus, since the liquid fuel synthesis system 1 according to the present embodiment directly uses the exhaust gas discharged from the reformer 12 as a heating medium, the size of the heat exchangers 100, 102, 104 provided in the system 1 is reduced. It is possible to reduce the size and efficiently heat liquid fuel and the like. Moreover, compared with the heating method using the conventional heat transfer oil etc., the thermal efficiency of the whole liquid fuel synthesis system can be improved about 5 to 10%. Furthermore, since it is not necessary to provide a facility for generating a new heat source such as a heat transfer oil, the entire liquid fuel synthesizing system 1 can be downsized.

  As mentioned above, although preferred embodiment of this invention was described referring an accompanying drawing, it cannot be overemphasized that this invention is not limited to this example. It will be apparent to those skilled in the art that various changes and modifications can be made within the scope of the claims, and these are naturally within the technical scope of the present invention. Understood.

  For example, in the above embodiment, natural gas is used as the hydrocarbon raw material supplied to the liquid fuel synthesizing system 1. However, the present invention is not limited to this example, and other hydrocarbon raw materials such as asphalt and residual oil are used. May be.

  In the above embodiment, the case where the liquid fuel synthesizing system 1 is provided with the decarboxylation device 20 has been described. However, depending on the case, the liquid fuel synthesizing system 1 may not be provided with the decarbonation device 20.

  In the above embodiment, the bubble column type slurry bed type reactor is used as the reactor for synthesizing the synthesis gas into the liquid hydrocarbon. However, the present invention is not limited to this example, and for example, a fixed bed type reactor. The FT synthesis reaction may be performed using such as.

The present invention relates to a reformer for reforming a hydrocarbon raw material to generate a synthesis gas mainly composed of carbon monoxide gas and hydrogen gas; and a liquid from the carbon monoxide gas and the hydrogen gas contained in the synthesis gas. A reactor for synthesizing hydrocarbons; a purification treatment device for performing a predetermined purification treatment on the liquid hydrocarbons synthesized in the reactor; and a liquid hydrocarbon introduced into the purification treatment device, the reformer A liquid fuel synthesizing system comprising: heating means for heating gas discharged from the heat source as a heat source.
According to the liquid fuel synthesis system of the present invention, the thermal efficiency of the entire liquid fuel synthesis system can be improved.

Claims (2)

A reformer for reforming a hydrocarbon raw material to produce a synthesis gas mainly composed of carbon monoxide gas and hydrogen gas;
A burner provided in the reformer for burning the supplied fuel gas and discharging the exhaust gas;
A reactor for synthesizing liquid hydrocarbons from carbon monoxide gas and hydrogen gas contained in the synthesis gas;
A purification treatment apparatus for performing a predetermined purification treatment on the liquid hydrocarbon synthesized in the reactor;
Heating means for heating the liquid hydrocarbon introduced into the purification apparatus using the exhaust gas discharged from a burner provided in the reformer as a heat source;
A liquid fuel synthesis system comprising:   The purification apparatus is at least one of a rectifying tower for fractionating the liquid hydrocarbon into a plurality of types of liquid fuels having different boiling points, or a hydrogenation reactor for hydrogenating the liquid hydrocarbon. Item 2. The liquid fuel synthesis system according to Item 1.

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