JP3791363B2 - Lightening of heavy oil - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method of reacting a hydrocarbon such as heavy oil with supercritical water to lighten the heavy oil and remove a metal content in the heavy oil. The present invention also relates to a method for achieving power generation such as a highly efficient combined cycle with the obtained light oil and supercritical water mixed fuel.
[0002]
[Prior art]
Since heavy oils with high viscosity and high sulfur and heavy metals are not suitable as high-efficiency power generation fuels, a method for converting them into light energy, desulfurization, demetalization and useful energy sources is disclosed in JP-A-11-80750, Japanese Laid-Open Patent Publication Nos. 2000-109850 and 2000-109851 have proposed.
[0003]
In any of the methods described in these publications, supercritical water and heavy oil, or alkali-added water such as Na and heavy oil are 20 MPa or more and about 400 ° C. (super critical point of water: 374 ° C., 22 .1 MPa) under the reaction conditions for thermal decomposition and hydrolysis, reduced pressure step for reducing the pressure of the reaction product, cooling the product after pressure reduction and separating it into gas, light oil, residue, water, etc. It consists of a separation process. In these configurations, when the final form is a low-pressure fuel gas and fuel liquid (light oil, residual oil), and the obtained gas and light oil fuel are used in a gas turbine combustor for highly efficient combined cycle power generation In addition, a gas compressor for compressing gas fuel is required, and gas and oil are supplied to the combustor, so that an apparatus for simultaneously burning the gas and oil is required.
[0004]
In the supercritical reaction process, the resulting light oil is completely dissolved in supercritical water by the dissolution action of supercritical water in addition to thermal decomposition and hydrolysis (clusters of several hundreds of water molecules and light oil molecules). For this reason, ultrafine oil droplets and water droplets are produced in a mixed state by cooling in the separation step (a state in which oil and water are emulsified), and separation of light oil and water is not easy.
[0005]
[Problems to be solved by the invention]
The present invention produces a high-pressure light fuel gas having good combustibility by causing catalytic reaction between supercritical water and heavy oil in a plurality of processes having different reaction conditions to lighten and demetalize heavy oil, and to produce a gas turbine. The purpose of the present invention is to provide a simple and highly efficient heavy oil reforming method that does not require a gas compressor even when used as fuel, and does not require a separation step of separating light oil and water. To do.
[0006]
[Means for Solving the Problems]
In order to solve the above problems, the following means were adopted.
[0007]
In order to efficiently reform heavy oil, the first invention is to bring a supercritical water and a heavy oil into contact with each other to dissolve a light fraction in the supercritical water and an insoluble heavy fraction (residual oil content). ) And a residual oil content reforming process in which the separated residual oil content is further brought into contact with supercritical water for reforming.
[0008]
In general, supercritical water or high-pressure hot water dissolves non-polar gas, hydrocarbon gas (methane, ethane, propane, etc.), oil that becomes liquid at room temperature and normal pressure, etc. to a considerable extent or completely, And the oil has a hydrolytic action that decomposes by reacting with hydrogen ions and hydroxide ions in supercritical water. However, these dissolution and hydrolysis actions are (1) temperature, (2) pressure, (3) partial pressure, (4) contact time, (5) solute (substance dissolved in supercritical water), etc. Will vary greatly.
[0009]
The first invention was made in order to make maximum use of the above-mentioned action in reforming heavy oil (V content is 1 ppm or less) with supercritical water. And a heavy oil of 320 MPa, 22.1 MPa or more, preferably 400 to 539 ° C. generated in a power plant to which the present invention is applied, a supercritical water of about 25 MPa, and a heavy oil of about 25 MPa heated up to 350 ° C. Oil ((supercritical water amount / heavy oil amount) = 0.25 to 2) is introduced into a dissolution / separation reactor, and H ₂ , CO, CO ₂ , CH ₄ , C ₂ H is obtained by hydrolysis in the reactor. ₆ , C ₂ H ₄ , C ₃ H ₈ , C ₃ H ₆ , C ₄ H ₁₀ , C ₄ H _{8 and} other gases and C5 to C20 light fractions are generated, and at the same time, these products are supercritical. Dissolves completely in water to form clusters consisting of water molecules and gas molecules, water molecules and light oil molecules. That. The mixture of clusters and supercritical water is sent to the combustor at the temperature and pressure to be used as fuel for the gas turbine. On the other hand, several percent of unreacted products and polycondensates that could not be hydrolyzed (hereinafter referred to as residual oil) are further lightened under these reaction conditions even if they are retained in the dissolution / separation process. Since it does not proceed, it is extracted from the melting / separating process and sent to the reforming process.
[0010]
In the reforming step, supercritical water about 1 to 4 times the amount of residual oil, preferably 539 to 593 ° C., about 23 to 25 MPa is supplied and brought into contact with the residual oil to make it more severe. Hydrolyze under conditions. As a result, the produced light oil molecules form clusters with supercritical water, and the mixture of clusters and supercritical water is sent to the combustor at the temperature and pressure to be used as gas turbine fuel. Depending on the type of heavy oil, substances that cannot be modified even in the reforming process, or inorganic substances remain, and these are discharged from the bottom of the reformer and processed separately.
[0011]
In the reforming step, an alkali metal can be added and a cracking catalyst or the like can be filled in order to accelerate the cracking reaction of the residual oil. Also, depending on the type of heavy oil (for example, A heavy oil, B heavy oil, C heavy oil, vacuum residual oil, orimulsion, oil sand, oil shell, waste oil, etc.), optimum temperature, pressure, steam in the dissolution / separation process and reforming process Since the partial pressures are different, the temperature, pressure, and water vapor partial pressure in the present invention are not limited. What is important is that it is divided into a dissolution / separation process and a reforming process, and in the dissolution / separation process, aliphatic and aromatic hydrocarbons that are relatively lightened are hydrolyzed with supercritical water to form clusters, and reforming. In the process, the residual oil having a high degree of polymerization is reformed with fresh, higher temperature supercritical water over a sufficient contact time to form a cluster. The mixture of clusters and supercritical water generated in each process (in gaseous form, this is collectively referred to as reformed fuel) is led to the combustor of the gas turbine as fuel at high temperature and high pressure. No gas compressor or oil-water separator is required. In addition, the two-stage reforming method can efficiently modify heavy oil because it can take the optimum temperature, water vapor partial pressure, and contact time corresponding to the change in the solvent substance, compared to the conventional one-step reforming. .
[0012]
The second invention relates to high-efficiency reforming and V removal of heavy oil in the case where the heavy oil contains a large amount of heavy metals such as vanadium (V), and supercritical water and heavy oil are brought into contact with each other. A dissolution / separation process that dissolves the light fraction in supercritical water and separates the undissolvable heavy fraction (residual oil), and a residual oil reforming process that further reforms the separated residual oil in contact with supercritical water. An oxidation process means is employed in which the residue extracted from the residual oil reforming process is burned to remove vanadium compounds.
[0013]
Heavy metals such as vanadium (V) are contained in heavy oils in the form of polyphyllin in polymers with a high degree of polymerization, and only move to the gas or light oil side by catalytic reaction with supercritical water. However, it remains in the polymer having a high degree of polymerization. In the second invention, the dissolution / separation process and the residual oil reforming process have the same basic functions as in the first invention, but the means of the oxidation process for actively removing and removing heavy metals such as V is adopted. ing.
[0014]
In the oxidation process, calcium compound, magnesium compound, dolomite and the like are filled, and residual oil extracted from the reforming process and oxidant such as air from outside the system are supplied to burn the residual oil. When heavy oil becomes CO ₂ and H ₂ O by combustion, heavy metals are oxidized and become metal oxides. For example, V becomes V ₂ O ₅ . V ₂ O ₅ reacts with the packing, becomes a compound such as CaO · V ₂ O ₅ (melting point 618 ° C.), MgO · V ₂ O ₅ (melting point 671 ° C.) and is trapped in the packing.
[0015]
The temperature in the oxidation step is about 450 ° C. to 900 ° C., and preferably burns at a temperature not exceeding the melting point of the substance that is a compound of V ₂ O ₅ and the filler. For example, the amount of oxidant such as air is adjusted so that it can be operated at 600 ° C. for CaO · V ₂ O ₅ (melting point 618 ° C.) and 650 ° C. for MgO · V ₂ O ₅ (melting point 671 ° C.). The pressure is preferably about 1 to 2 atmospheres in order to facilitate the taking in and out of the packing material and to reduce the supply power cost of the combustion air. By making the packing shape into particles crushed to about 0.1 to 2 mm, handling during filling and discharging becomes easy. The layer state of the particles in the oxidizer is preferably a stationary phase, a moving bed, or a fluidized bed.
[0016]
The filler is selected depending on the properties of the heavy oil to be treated. When processing residual oil containing a large amount of sulfur and heavy metals, the calcium-based compounds such as limestone and dolomato are selected and the oxidizer. If the lower temperature is 850 ° C. and the upper temperature is about 600 ° C., the SO ₂ gas generated during combustion reacts with limestone in the lower part and becomes CaSO ₄ and is fixed, and V ₂ O ₅ is CaO. V ₂ O ₅ (melting point 618 ° C.) and fixed. That is, not only heavy metal oxides but also sulfur oxides can be removed. When mainly removing heavy metal, Fe-based oxide, Mg-based oxide, or Ni-based oxide is used as the filler, and Fe ₂ O ₃ · V ₂ O ₅ (melting point 860 ° C.), MgO · V _{2 is used.} It can also be fixed as O ₅ (melting point 671 ° C.), 2NiO · V ₂ O ₅ (melting point 900 ° C.). The particles with V and S fixed are discharged from the oxidation process and used for recovery of V.
[0017]
According to a third invention, in the first and second inventions, new supercritical water is supplied to the reforming step of the residual oil to increase the partial pressure of water vapor, and the temperature of the reforming step is set higher than that of the dissolving step. By increasing it, hydrolysis is performed under more severe conditions.
[0018]
In the fourth invention, the pressure in the oxidation process in the second invention is made lower than the pressure in the dissolution / separation process and the residual oil reforming process, and it is preferable to operate at about 1 to 2 atm to facilitate loading and unloading of the packing material. This is to reduce the supply power cost of the combustion air.
[0019]
The fifth invention is for achieving high-efficiency power generation by power generation using the reformed oil (supercritical water in which oil is dissolved) obtained in the first invention or the second invention as a fuel.
[0020]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.
[0021]
Example 1
FIG. 1 shows a lightening method using heavy oil (mixed oil of C heavy oil and waste oil, mixed oil having a fraction of C15 or more, V content 20 ppm). This system is composed of a heavy oil and supercritical water supply system, a dissolution / separation process 1, a reforming process 2, and piping connecting each process. Heavy oil is heated to 50 ° C. in a tank, heated to 350 ° C. by an extra-tube heater while being transported at 24 g / min by a pump, and supplied to the dissolution / separation step 1. Water is heated to 450 ° C. by an extra-tube heater while being transported at a rate of 24 g / min by a pump, and supplied to the dissolution / separation process 1 as supercritical water. In the dissolution / separation step, the heavy oil is supercritically treated at a liquid-based space velocity of 10 h ⁻¹ while being maintained at 390 ° C. to 25 MPa to produce a reformed fuel composed of a mixed gas of clusters and supercritical water. The reformed fuel is supplied to the gas turbine combustor through the reformed fuel extraction pipe 3 and the pressure control valve 4. On the other hand, the residual oil not dissolved in the dissolution / separation process 1 is supplied to the reforming process 2 through the residual oil extraction pipe 5 and the residual oil extraction valve 6 at 0.8 g / min. In the reforming step 2, supercritical water at 550 ° C.-25 MPa is supplied from the supercritical water supply pipe 7 at 1.6 g / min, the reforming step 2 is maintained at 450 ° C.-25 MPa, and the liquid-based space velocity 2 h ^The residual oil is reacted at ^-1 to generate reformed fuel, and the reformed fuel is returned to the melting / separating process through the reformed fuel pipe 8. The reformed fuel produced by the above operation was collected after cooling under reduced pressure, and its composition was examined. Gaseous material at room temperature _{H 2, CO, CO 2,} C1~C4, V lighter oil component in oil in fraction or C5 was 0.8 ppm. The calorific value of the reformed fuel containing water vapor was 4500 kcal / kg. Further, even when the amount of supercritical water / heavy oil was changed to 0.25-2 (the liquid-based space velocity was the same), V in the light oil was 0.8 ppm.
[0022]
Example 2
FIG. 2 shows a lightening method using a vacuum residue oil as a heavy oil (a fraction having an initial boiling point of 375 ° C. or higher under normal pressure, a V content of 150 ppm). This system connects high pressure heavy oil, supercritical water supply system, dissolution / separation process 1, reforming process 2 and normal pressure oxidation process 20, heat recovery unit 21, dedusting unit 22, and each process. Consists of piping. The heavy oil is heated to 120 ° C. in a tank, heated to 370 ° C. by an external heater while being transported by a pump at 24 g / min, and supplied to the dissolution / separation step 1. Water is heated to 450 ° C. by an extra-tube heater while being transported at a rate of 24 g / min by a pump, and supplied to the dissolution / separation process 1 as supercritical water. In the dissolution / separation step, the heavy oil is supercritically treated at a liquid-based space velocity of 10 h ⁻¹ while being maintained at 390 ° C. to 25 MPa to produce a reformed fuel composed of a mixed gas of clusters and supercritical water. The reformed fuel is supplied to the gas turbine combustor through the reformed fuel extraction pipe 3 and the pressure control valve 4. On the other hand, the residual oil not dissolved in the dissolution / separation process 1 is supplied to the reforming process 2 through the residual oil extraction pipe 5 and the residual oil extraction valve 6 at 5 g / min. In the reforming step 2, supercritical water at 550 ° C.-25 MPa is supplied from the supercritical water supply pipe 7 at 20 g / min, the reforming step 2 is maintained at 450 ° C.-25 MPa, and the liquid-based space velocity 2 h ^−1. Then, the residual oil is reacted to generate reformed fuel, and the reformed fuel is returned to the melting / separating process through the reformed fuel pipe 8. On the other hand, the residual oil that has not been reformed in the reforming step 2 is sent to the atmospheric pressure oxidation step 20 at 2 g / min via the residual oil discharge pipe 9 and the residual oil discharge valve 23. In the oxidation step, limestone having an average particle diameter of 0.5 mm is filled through a filler supply pipe 27 (the filler is discharged through a filler discharge pipe 28). Further, air is supplied at 64 g / min from outside the system to the oxidation step 20 through the oxidant supply pipe 24, and the residual oil is burned at 600 ° C. By combustion, C, H, and S in the residual oil become CO ₂ , H ₂ O, and SO ₂ , and V metal contained in the residual oil becomes V ₂ O ₅ . SO ₂ and V ₂ O ₅ react with the packing to become CaSO ₄ and CaO · V ₂ O ₅ and are chemisorbed onto the solid packing. The combustion exhaust gas is cooled to about 120 ° C. by the heat recovery unit 21 through the exhaust pipe 25, and then the entrained particulates are separated by the dust remover 22 and then discharged from the pipe 26. In the oxidation step 20, 99.4% of V and 58% of S contained in the heavy oil were chemisorbed.
[0023]
Example 3
In the apparatus of Example 2, dolomite having an average particle diameter of 0.5 mm was used as a filler in the oxidation step, and the modification was performed under the conditions of Example 2. The reformed fuel discharged from the pressure control valve 4 was 66 g / min, and V in the liquid fraction of C5 or higher was 1 ppm or less. In the dolomite charged in the oxidation step 20, 99.3% of V and 63% of S contained in the heavy oil were adsorbed. V became MgO · V ₂ O ₅ and CaO · V ₂ O ₅ , and adhered to the solid packing.
[0024]
Example 4
In the apparatus of Example 2, in the reforming step, an equimolar amount of NaOH was supplied with respect to S in the heavy oil and reformed under the conditions of Example 2. The reformed fuel discharged from the pressure control valve 4 was 66 g / min, and V in the liquid fraction of C5 or higher was 1 ppm or less. In the limestone charged in the oxidation step 20, 99.3% of V and 83% of S contained in the heavy oil were adsorbed. V became CaO · V ₂ O _{5 and} was deposited on the solid packing.
[0025]
Example 5
FIG. 3 shows a high-efficiency power generation system using heavy oil lighter fuel.
[0026]
Melting / separation step 1, reforming step 2 and atmospheric pressure oxidation step 20, combustor 31, gas turbine 32, air compressor 33, exhaust heat recovery device 34, environmental device 35 (denitration, desulfurization, dust removal), steam The turbine 36 is configured. The reformed fuel generated in the dissolution / separation process 1 and the reforming process 2 is supplied to the gas turbine combustor 31 through the reformed fuel extraction pipe 3, the pressure control valve 4, and the fuel supply pipe 37. The combustor 31 receives the air from the air compressor 33 from the conduit 38 and burns the reformed fuel. The combustion gas drives the gas turbine 32 and is used for power generation, and then sent to the exhaust heat recovery unit 34. A heat transfer pipe 39 is installed in the exhaust heat recovery unit 34, and power is generated by exhaust heat recovery in a power generation system including a feed water pump 40, a steam turbine 36, and the like connected thereto. The exhaust gas exiting the exhaust heat recovery device 34 is purified by the environmental device 35 and released outside the system. On the other hand, the combustion exhaust gas generated in the oxidation step 20 is sent to the exhaust heat recovery unit 34 through the exhaust pipe 25 and the pipe 26 and is recovered by the exhaust heat recovery unit.
[0027]
This system does not describe how to heat heavy oil and generate supercritical water, but install a heat transfer tube for heating heavy oil and a heat transfer tube for generating supercritical water in the exhaust heat recovery unit 34. And they can be achieved.
[0028]
【The invention's effect】
According to the present invention, a light oil fuel demetalized from heavy oil can be produced. Therefore, when used as a gas turbine fuel, a gas compressor is unnecessary, a separation step for separating light oil and water is unnecessary, An efficient power generation system becomes possible.
[Brief description of the drawings]
FIG. 1 is a schematic diagram showing the configuration of an embodiment of the present invention.
FIG. 2 is a schematic diagram showing the configuration of another embodiment according to the present invention.
FIG. 3 is a schematic view of a power generation system according to the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Dissolution / separation process, 2 ... Reforming process, 3 ... Reformed fuel extraction pipe, 4 ... Pressure control valve, 5 ... Residual oil extraction pipe, 6 ... Residual oil extraction valve, 7 ... Supercritical water supply pipe, 8 ... reformed fuel pipe, 9 ... residue oil discharge pipe, 20 ... oxidation process, 21 ... heat recovery device, 22 ... dust remover, 23 ... residue oil discharge valve, 24 ... oxidant supply pipe, 25 ... discharge pipe , 26 ... piping, 31 ... combustor, 32 ... gas turbine, 33 ... air compressor, 34 ... exhaust heat recovery device, 35 ... environmental equipment, 36 ... steam turbine, 37 ... fuel supply pipe, 38 ... conduit, 39 ... Heat transfer tube, 40 ... feed pump.

Claims (5)

In the method of producing light fuel by mixing supercritical water and heavy oil, the supercritical water and heavy oil are brought into contact with each other to dissolve the light fraction in supercritical water and to dissolve the heavy fraction that cannot be dissolved (residual oil) A method for lightening heavy oil, comprising: a dissolving / separating step for separating oil; and a residual oil reforming step in which the separated residual oil is further brought into contact with supercritical water for reforming. In the method of producing light fuel by mixing supercritical water and heavy oil, the supercritical water and heavy oil are brought into contact with each other to dissolve the light fraction in supercritical water and to dissolve the heavy fraction that cannot be dissolved (residual oil) A dissolution / separation process for separating the residual oil, a residual oil reforming process for bringing the separated residual oil into contact with supercritical water for reforming, and an oxidation process for combusting the residue from the residual oil reforming process A method for reducing the weight of heavy oil. 3. The method according to claim 1, wherein new supercritical water is supplied to the residual oil reforming step to increase the water vapor partial pressure, and the temperature of the residual oil reforming step is higher than that of the dissolving step. Lightening method of quality oil. 3. The method for lightening heavy oil according to claim 2, wherein the pressure in the oxidation step is made lower than the pressure in the dissolution / separation step and the residual oil reforming step, and an oxidizing agent is supplied. A power generation method using heavy oil, wherein power is generated using supercritical water obtained by dissolving the oil obtained in claim 1 or 2 as fuel.

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