JPH11246876A - Method for generating flammable gas, its device and hybrid power generator using the same gas - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a miniturized combustible gas generator having relatively little restriction in heat resistance without environmental pollution by simply and efficiently gasifying various kinds of coals or heavy crude oils at relatively low temperatures, easily bringing sulfur components included in coals and heavy crude oils into nontoxic inorganic salts and removing them, and a hybrid power generator by combining the said generator with a usual hybrid power generator. SOLUTION: This method for producing combustible gases is to decompose one or both of a coal slurry and a heavy oil emulsion by maintaining one or both of them in a subcritical or supercritical state, separate the oils and residues obtained from the decomposition process 11 in the subcritical or supercritical state, produce active hydrogen by adding an oxygen source to the residue in the subcritical or supercritical state separated in the separation process 12, feed the active hydrogen produced in the partial oxidation process 13 to a decomposing reaction process and produce high temperature and high pressure combustible gases in a gasification process 14 by reducing pressure or decreasing temperature of the oil components in the subcritical or supercritical state separated in the separation process 12.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for decomposing coal or heavy oil in a subcritical state or a supercritical state, and decompressing or lowering the temperature of the oil produced by the decomposition to produce a high-temperature and high-pressure combustible gas. Regarding the device. Furthermore, the present invention relates to a combined power generation device for generating electric power by using a high-temperature and high-pressure combustible gas generated by the device.

[0002]

2. Description of the Related Art As a power generation device, a thermal power generation device that converts combustion energy of fossil fuels such as coal, heavy oil, and natural gas into steam by a boiler and drives a steam turbine with the steam energy to generate power is well known. is there. In this power generation device, a large amount of sulfur and the like contained in fossil fuel is generated as impurities. For this reason, a thermal power generator requires a complicated purification device so that these impurities do not become harmful substances and cause environmental pollution. There is also a problem that high power generation efficiency cannot be obtained. In order to improve the power generation efficiency, as shown in FIG. 3, there is known a coal gasification combined power generation device 5 including a gasification device 1, a desulfurization device 2, and a combined power generation device 3. In this power generation device 5, pulverized and dried coal is supplied to the upper furnace of the two-stage fluidized bed gasifier 1, and the coal is gasified by hot gas from the lower furnace and air as a gasifying agent entering the upper stage. Become The generated gas here is taken out from the furnace top as a crude gas after heat exchange. The unreacted char coarse particles that have not been gasified are collected by an inverted L-shaped overflow (not shown), and the fine particles in the coarse gas are collected by a cyclone 1a. The gas is recovered in the furnace and burned by air and steam again to be gasified. Ash is taken out from the furnace bottom and tank 1
b.

[0003] The crude gas taken out of the gasifier 1 is combined with a sulfur compound by iron oxide by a desulfurizer 2 to remove sulfur in the form of iron sulfide, and the SO ₂ gas generated at that time is converted into elemental sulfur. It is reduced and collected. The crude gas taken out of the desulfurization device 2 is removed by a dust collector 2a and dust is removed by a dust separator 2b to become a combustible gas. The combined power generation facility 3 includes a gas turbine 6 and a steam turbine 7. The combustible gas is first mixed with air compressed by the gas turbine compressor 6a and burns in the gas turbine combustor 6b. The combustion gas drives the gas turbine 6 and generates electric power by a generator 8 having a rotating shaft directly connected to the gas turbine 6. Next, the exhaust gas from the gas turbine 6 is recovered by the exhaust heat recovery boiler 9 using the heat energy as steam energy.
This steam energy drives the steam turbine 7 and generates electricity by a generator 8 having a rotating shaft directly connected to the steam turbine 7.

[0004]

However, in the above-mentioned integrated coal gasification combined cycle system, the gasification system and the desulfurization system are relatively large in size, and the control thereof is complicated. Further, since gasification of coal is performed at a temperature of 1000 ° C. or higher, the gasifier is restricted by many severe conditions for withstanding high temperatures, and thermal energy loss increases. SUMMARY OF THE INVENTION It is an object of the present invention to provide a method and apparatus for producing a combustible gas which can efficiently gasify various types of coal or heavy oil at a relatively low temperature and efficiently. Another object of the present invention is to provide a method and an apparatus for producing a combustible gas which does not cause environmental pollution by easily removing a sulfur content contained in coal or heavy oil into a harmless inorganic salt and removing it. . Another object of the present invention is to provide a combustible gas generation device which has relatively few restrictions on heat resistance and can be downsized. Still another object of the present invention is to provide a combined power generation device that can achieve high power generation efficiency by being combined with a conventional combined power generation facility.

[0005]

The invention according to claim 1 is
As shown in FIG. 1, one or both of a slurry of finely divided coal and water or a heavy oil and water emulsion is maintained in a subcritical state or a supercritical state to decompose one or both of coal and heavy oil. Decomposition reaction step 11 and the decomposition reaction step 1
A separation step 12 for separating the oil component and the residue obtained in Step 1 in a subcritical or supercritical state, and adding an oxygen source to the subcritical or supercritical state separated in the separation step 12 to activate hydrogen. A partial oxidation step 13 for producing and supplying the same to the decomposition reaction step 11, and reducing one or both of the pressure and the temperature of the oil component in the subcritical state or the supercritical state separated in the separation step 12, thereby reducing the temperature and the temperature. And a gasification step 14 for generating combustible gas.

The invention according to claim 2 is the invention according to claim 1, and is a method for producing a combustible gas by adding an aqueous alkali solution together with one or both of a slurry and an emulsion. The invention according to claim 3 is the invention according to claim 1 or 2, which is a method for generating a combustible gas that supplies the heavy oil that has not been gasified in the gasification step 14 to the cracking reaction step 11 again. The invention according to claim 4 is a method for producing a combustible gas used for burning heavy oil not gasified in the gasification step 14 to create a high temperature in a subcritical state or a supercritical state.

As shown in FIG. 2, the invention according to claim 5 comprises a tank 21 for storing one or both of a slurry of finely divided coal and water or an emulsion of heavy oil and water, and one or both of a slurry and an emulsion. Is maintained in a subcritical state or a supercritical state to decompose one or both of coal and heavy oil, and an oil component and a residue obtained by the decomposition reaction apparatus 24 are converted into a subcritical state or a supercritical state. And a partial oxidation device 27 which generates an active hydrogen by adding an oxygen source to the subcritical or supercritical residue separated by the separation device 26 and supplies it to the decomposition reactor 24.
And a gasifier 28 that generates a high-temperature and high-pressure combustible gas by reducing one or both of the pressure and the temperature of the oil component in the subcritical or supercritical state separated by the separation device 26. It is a gas generator 20.

According to a sixth aspect of the present invention, as shown in FIG. 2, the gas turbine 31 driven by the combustion energy of the high-temperature and high-pressure combustible gas generated by the generating apparatus according to the fifth aspect, and the exhaust gas of the gas turbine 31 Heat recovery boiler 33 for recovering the heat energy of the steam as steam energy, and heat recovery steam generator 3
, Steam turbines 32 and 36 driven by the steam energy recovered in the gas turbine 31 and the steam turbine 3
This is a combined power generation apparatus including one or two or more generators 34 and 37 that generate electric power using rotational energy of 2, 36.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION In the present invention, the subcritical state of water is a temperature of 200 to 374 ° C. and 160 to 215 kg.
Means the state of water at a pressure of / cm ² . The supercritical state of water is a temperature of 374 to 900 ° C. and 215 to 3
It means the state of water at a pressure of 00 kg / cm ² . If the temperature and pressure in the subcritical state are lower than the lower limits, the reaction is slow and the decomposition efficiency is not good. If the temperature and pressure in the supercritical state exceed the upper limits, the load on the decomposition reactor is too high, which is also inefficient. In the invention according to claim 1, as shown in FIG. 1, one or both of a coal slurry and a heavy oil emulsion are supplied to a decomposition reaction step 11, and further after a separation step 12 and a partial oxidation step 13, In the gasification step 14, it is gasified to become combustible gas.
Reference numeral 15 in FIG. 1 indicates a range maintained in a subcritical state or a supercritical state.

First, when the raw material is coal, a decomposition reaction step 11
It is considered that the hydrolysis reaction of coal, the thermal decomposition reaction of coal, and the hydrogenation reaction occur in the coal slurry in the subcritical state or supercritical state. That is, in high-temperature water, non-covalent bonds such as hydrogen bonds in coal are dissociated, and the coal expands. Thereby, the decomposition and liquefaction reaction of coal proceeds more effectively. In the coal hydrolysis reaction, OH ⁻ and H ⁺ of H ₂ O are added to a hetero element portion connecting the benzene ring of the coal, and the coal is reduced in molecular weight. In the thermal decomposition reaction of coal, the coal is simply pyrolyzed and decomposed. Further, in the hydrogenation reaction, H is added to the radical generated during the above reaction, whereby the thermally decomposed species is stabilized. In addition, a reaction between hydrogen and stable molecules that does not thermally decompose occurs. Here, a hydrogenation reaction can also occur in the hydroxyl group and the carboxylic acid group generated by the hydrolysis, but the hydrogen reaction to the above-mentioned radical occurs more predominantly. The above reactions (1) to (4) are not performed individually, but are performed simultaneously and in a complex manner, and lightening of coal proceeds. When the raw material is heavy oil, it is considered that the above-mentioned reactions (1) to (3) are similarly performed on the heavy oil emulsion in the decomposition reaction step 11. In this way, one or both of coal and heavy oil are decomposed into oil and residue by this subcritical or supercritical state.

The cracked oil and residue are separated in a subcritical or supercritical state in the next separation step 12. When an oxygen source is added to this residue in the partial oxidation step 13, a reaction represented by the following equation (1) occurs. 2C + O ₂ → 2CO (1) As shown in the equation (1), the char which is a residue produced by coal liquefaction is partially oxidized to carbon monoxide, and a water gas shift reaction shown in the following equation (2) To generate active hydrogen. In the water gas shift reaction of the formula (2), CO generated by partial oxidation is immediately reacted with H ₂ O. Here, the char is the one that has not been completely decomposed or the one that has been re-polymerized by the pyrolysis reaction of the coal and the pyrolysis reaction of the coal. Residuals generated without heavy oil being completely decomposed also generate carbon monoxide by partial oxidation according to the char. CO 2 + H ₂ O → CO ₂ + H ₂ (2) The active hydrogen generated in the partial oxidation step 13 as shown in the equation (2) is supplied to the decomposition reaction step 11 and the decomposition reaction step 1 is performed.
The heavy oil in the decomposition product in 1 is further lightened. At the same time, the post-treatment of the residue generated in the decomposition reaction is reduced. Separation process 1
In the gasification step 14, one or both of the pressure and the temperature of the subcritical or supercritical oil separated in 2 are reduced, and a part of the oil becomes heavy oil but a large part becomes a combustible gas. The combustible gas drives a gas turbine provided in the combined cycle power plant 30 to generate power, recovers exhaust heat of the gas turbine, converts the exhaust heat into steam energy, and drives the steam turbine with the steam energy. Generate electricity.

When coal or heavy oil contains sulfur, it is dissolved in supercritical water via sulfur oxide (SOx) in a decomposition reaction step 11. According to the second aspect of the present invention, an aqueous alkali solution is added to one or both of the slurry and the emulsion and supplied to the decomposition reaction step 11. As shown in the following formulas (3) and (4), for example, this alkali (NaO
H) converts sulfur oxides (SO ₃ ) into harmless sulfates (Na ₂ SO
₄ ) SO ₃ + H ₂ O → H ₂ SO ₄ (3) H ₂ SO ₄ + 2NaOH → Na ₂ SO ₄ + 2H ₂ O (4) In the invention according to the third aspect, gas is used in the gasification step 14. The unconverted heavy oil is supplied again to the cracking reaction step 11 to make it a lower molecular weight medium / light oil. Further, in the invention according to claim 4, the heavy oil not gasified in the gasification step 14 is used as a fuel, which is burned, and the decomposition energy reactor, the separation device and the partial oxidation device are brought into a subcritical state or a supercritical state by the heat energy. Make the state high temperature. Thereby, the energy supplied to these devices from the outside can be reduced.

Next, a combustible gas generator according to the present invention and a combined power generator using the same will be described with reference to the drawings. FIG.
As shown in (1), the combined power generation device includes a combustible gas generation device 20 that generates a high-temperature and high-pressure combustible gas, and a combined power generation device 30 that generates power using the high-temperature and high-pressure combustible gas generated by the device 20. The combustible gas generator 20 includes a tank 21 for storing one or both of a slurry of finely divided coal and water or an emulsion of heavy oil and water, and a decomposition for decomposing the coal and heavy oil stored in the tank 21. A reaction device 24, a separation device 26 for separating oil and residue obtained by the decomposition reaction device 24, and an oxygen source added to the residue separated by the separation device 26 to generate active hydrogen, which is subjected to a decomposition reaction. A partial oxidation device 27 for supplying to the device 24 and a separation device 2
And a gasifier 28 that generates a high-temperature and high-pressure combustible gas by reducing one or both of the pressure and the temperature of the subcritical or supercritical oil separated in 6. Cracking of coal and heavy oil in the cracking reactor 24,
The separation of the oil and the residue in the separation device 26 and the generation of active hydrogen in the partial oxidation device 27 are all performed while maintaining the subcritical state or the supercritical state. The combined cycle power plant 30 includes a gas turbine 31 driven by the combustion energy of the combustible gas generated by the generator 20, a steam turbine 32, and an exhaust heat recovery boiler 33 that recovers thermal energy of exhaust gas from the gas turbine 31. And a generator 34 for generating electric power by the turbines 31 and 32.

In the combustible gas generator configured as described above, the combustible gas is generated through the following steps, and then power is generated by the combustible gas in the combined power generation facility. <Decomposition reaction step> In the decomposition reaction step, one or both of coal or heavy oil is maintained by maintaining one or both of a slurry of finely divided coal and water or an emulsion of heavy oil and water in a subcritical or supercritical state. This is the step of decomposing. In this embodiment, finely divided coal, heavy oil, water and an aqueous alkaline solution are uniformly mixed and stored in a tank 21 in a slurry state. Examples of coal include grass coal, lignite, sub-bituminous coal, bituminous coal, anthracite, and the like.
An aqueous solution of OH, Ca (OH) ₂ or the like is exemplified. Coal is preliminarily 30 mm or less, preferably 30 mm depending on the pump capacity.
Finely pulverized to a particle size of 0 μm or less. Water in the slurry is added so that the slurry concentration is preferably 5 to 60% by weight. If the slurry concentration is less than 5% by weight, the decomposition efficiency of coal is poor, and if it exceeds 60% by weight, the slurry lacks fluidity and is difficult to handle. Slurry concentration is 40-55
% Is more preferred.

The slurry discharged from the tank 21 is pumped by a pump 22 and sent to a heater 23. In the heater 23, the slurry is heated to about 150 to 350 ° C.
The slurry heated by the heater 13 is supplied to a decomposition reaction device 24, where the pressure is further increased and the temperature is increased, and here, a supercritical state is established. In the decomposition reaction device 24, the slurry
While maintaining the supercritical state at ８００800 ° C. and an average density of 0.4 g / cm ³ , the above-mentioned reactions 〜 occur concurrently with each other to form a complex. Water in a supercritical state promotes the hydrolysis reaction of coal and heavy oil because the dissociation into hydrogen ions and hydroxyl ions is larger than normal water and at a higher temperature. Furthermore, supercritical water expands coal due to its low dielectric constant,
It has some dissolving power to coal itself or heavy oil and can be uniformly mixed with gas. These also contribute to the promotion of lightening. Further, since the supercritical state extremely lowers the solubility of the sulfur oxide, the sulfur oxide is easily dissolved in water in the supercritical state. As a result, the sulfur content in the decomposition reactor 24 becomes a harmless inorganic salt in the above-described reactions of the formulas (3) and (4). The decomposition product of the slurry is a residue containing an oil component composed of heavy oil, medium / light oil, and the like, and char and inorganic salts. The oil and the residue are separated in a supercritical state by a separation device 26 provided on the discharge side of the decomposition reaction device 24.

<Separation Step> The separation step is a step of separating the oil and the residue obtained in the decomposition reaction step in a subcritical state or a supercritical state. This separation is performed by a separation device 26. The separation device 26 is a cyclone 26a for removing the residue generated in the decomposition reaction device 24 and a filter 2 for removing the residue (dust) remaining without being completely removed by the cyclone 26a.
6b.

<Partial Oxidation Step> The partial oxidation step is a step in which an oxygen source is added to the subcritical or supercritical residue separated in the separation step to generate active hydrogen, and this is supplied to a decomposition reactor. is there. This partial oxidation is performed by a partial oxidation device 27. In the partial oxidation device 27, the cyclone 26
By adding an oxygen source such as air, hydrogen peroxide or oxygen to the residue separated by the filter a and the filter 26b while maintaining the supercritical state, the carbon content in the residue is reduced as shown in the above formula (1). Partially oxidizes to carbon oxide. Also in the reaction of the above formula (1), the activation energy in high-density water is reduced to about 1/3 of the usual value, which also contributes to prompt reaction of CO generated by thermal decomposition. In the partial oxidation device 27, active hydrogen is generated by causing a water gas shift reaction represented by the above formula (2). The active hydrogen is sent to the cracking reaction device 24 to further promote the lightening of heavy oil generated by the cracking of coal. Even in the reaction of the above formula (1), in high-density water, the heat necessary for the reaction in the active partial oxidation step can be covered by the combustion heat of the residue, and this combustion heat is sufficiently high and continuously generated. In this case, there is no need to supply energy from the outside. In the reaction of the formulas (1) and (2), CoMo /
It is also possible to use a catalyst such as Al ₂ O ₃ , NiW / Al ₂ O ₃ , NiW / zeolite to promote lightening or desulfurization or denitrification of the converted oil. Inorganic salts, ash, etc., which have not reacted in the partial oxidation, are removed from the partial oxidation device 27 and disposed.

<Gasification Step> In the gasification step, one or both of the pressure and the temperature of the subcritical or supercritical oil separated in the separation step are reduced to generate a high-temperature and high-pressure combustible gas. This is the step of performing This gasification is performed by a gasifier 28. The gasifier 28 includes a pressure reducing valve 28a for reducing the pressure of the supercritical oil passing through the filter 26b and a tank 28 for lowering the temperature of the oil.
b. By the predetermined pressure reduction and temperature reduction, the tank 28
Water is extracted from the oil content in b and a part of the oil becomes heavy oil. Most of the rest is flammable gas mainly composed of methane, ethane, benzene and the like at high temperature and pressure. Most of the heavy oil extracted from the tank 28b is sent to the cracking reactor 24, where it is lightened. A part of the heavy oil is used as a temperature control heat source for maintaining the cracking reaction device 24, the separation device 26, and the partial oxidation device 27 in a subcritical state or a supercritical state. The water is supplied to a tank 21 for reuse or disposed as waste water.

<Combined Power Generation> The high temperature and high pressure combustible gas from the gasifier 28 mainly containing methane, ethane, benzene, etc. is mixed with air compressed by the gas turbine compressor 31a of the combined power generation facility 30, Gas turbine combustor 31b
Combustion. This combustion gas drives the gas turbine 31, and the generator 3 has a rotating shaft directly connected to the gas turbine 31.
4 to generate electricity. Next, the exhaust gas from the gas turbine 31 is recovered by the exhaust heat recovery boiler 33 using the heat energy as steam energy. This steam energy is supplied to the steam turbine 3
2 is driven, and power is generated by a generator 34 having a rotating shaft directly connected to the steam turbine 32. The exhaust gas generated in the exhaust heat recovery boiler 33 is discharged from the chimney 35. Thereby, power generation is performed with high power generation efficiency. A steam turbine 36 is provided instead of the steam turbine 32 as shown in FIG.
Alternatively, power may be generated by another generator 37.

[0020]

As described above, the present invention decomposes and separates a coal slurry or a heavy oil emulsion in a subcritical or supercritical state to generate a combustible gas, and utilizes the combustion energy of the combustible gas. This has the following excellent effects. (1) Since the gasification temperature is lower than that of conventional gasifiers, there are fewer restrictions on the materials that make up the unit, and the combustible gas generated is of high temperature and pressure. Thus, the energy required for gas compression of the gas turbine can be reduced. (2) If an alkaline aqueous solution is added together with the raw materials, sulfur contained in coal and heavy oil can be removed in the form of inorganic salts. For this reason, a large-sized desulfurization unit used in the conventional combined cycle power generation device is not required, and low-grade coal, heavy oil, or the like having a relatively high sulfur content can be used as a raw material. (3) Gasification of coal or heavy oil using high pressure supercritical water makes it possible to construct the equipment itself relatively compact. Further, the combustible gas generator of the present invention can be provided instead of the gasifier in the conventional combined cycle power generator or as an additional facility.

[Brief description of the drawings]

FIG. 1 is a view showing a process of generating a combustible gas of the present invention and a process of generating power using the combustible gas.

FIG. 2 is a configuration diagram of a combustible gas generation device and a combined power generation facility of the present invention.

FIG. 3 is a configuration diagram of a conventional integrated coal gasification combined cycle device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 11 Decomposition reaction process 12 Separation process 13 Partial oxidation process 14 Gasification process 20 Combustible gas generator 21 Tank 24 Decomposition reaction device 26 Separation device 27 Partial oxidation device 28 Gasifier 30 Combined power generation facility 31 Gas turbine 32, 36 Steam turbine 33 Waste heat recovery boiler 34, 37 Generator

Claims (6)

[Claims] 1. Decomposing one or both of the coal or heavy oil by maintaining one or both of a finely divided coal and water slurry or a heavy oil and water emulsion in a subcritical or supercritical state. A cracking reaction step (11), a separation step (12) of separating the oil and the residue obtained in the cracking reaction step in a subcritical state or a supercritical state, and a subcritical state or a supercritical state separated in the separation step. A partial oxidation step (13) in which an oxygen source is added to the residue in the critical state to generate active hydrogen and supplied to the decomposition reaction step, and the pressure or temperature of the subcritical or supercritical oil separated in the separation step Gasification step of producing high-temperature, high-pressure combustible gas by reducing one or both of
(14) A method for producing combustible gas comprising: 2. The method for producing a combustible gas according to claim 1, wherein an alkaline aqueous solution is added together with one or both of the slurry and the emulsion. 3. The method according to claim 1, wherein the heavy oil not gasified in the gasification step (14) is supplied again to the cracking reaction step (11). 4. The production of a combustible gas according to claim 1, wherein the heavy oil which has not been gasified in the gasification step (14) is burned to create a high temperature in a subcritical state or a supercritical state. Method. 5. A tank (2) for storing one or both of a slurry of finely divided coal and water or an emulsion of heavy oil and water.
1), a cracking reactor (24) that cracks one or both of the coal and heavy oil while maintaining one or both of the slurry and the emulsion in a subcritical or supercritical state, and the cracking reactor ( A separation device (26) for separating the oil and residue obtained in 24) in a subcritical or supercritical state, and an oxygen source for the subcritical or supercritical residue separated in the separation device (26). And a partial oxidation device (27) that generates active hydrogen and supplies it to the decomposition reaction device (24), and the pressure or temperature of the subcritical or supercritical oil separated by the separation device (26). A gasifier (28) for generating a high-temperature and high-pressure combustible gas by lowering one or both of them. 6. A gas turbine driven by the combustion energy of a high-temperature and high-pressure combustible gas generated by the generation device according to claim 5, and heat energy of exhaust gas of the gas turbine is converted into steam energy. An exhaust heat recovery boiler (33) to be recovered, a steam turbine (32, 36) driven by steam energy recovered by the exhaust heat recovery boiler (33), the gas turbine (31) and the steam turbine (32 , 36) and one or more generators (34,
37).