JP6390334B2 - Chemical loop combustion apparatus and chemical loop combustion method - Google Patents

Description

  The present invention relates to a chemical loop combustion apparatus and a chemical loop combustion method.

  In order to suppress global warming, it is necessary to recover the carbon dioxide produced with the combustion of fossil fuels. The exhaust gas generated by the combustion of fossil fuel contains not only carbon dioxide but also oxygen, nitrogen or nitrogen oxides derived from air. Therefore, in order to collect carbon dioxide, a process for separating carbon dioxide from exhaust gas is required. However, a great deal of energy is consumed in the separation process. For example, in the carbon dioxide adsorption / desorption process, a large amount of energy is required to control the temperature of the adsorbent or the pressure of the atmosphere surrounding the adsorbent.

  In recent years, a method called chemical loop combustion (chemical combustion) has attracted attention as a method for easily recovering carbon dioxide in exhaust gas (see Patent Document 1 below). An apparatus for performing chemical loop combustion (chemical loop combustion apparatus) includes an air reactor and a fuel reactor. In the chemical loop combustion method, oxygen carrier particles (powder) containing metal are oxidized with oxygen in the air in an air reactor. In the air reactor, since there is no fuel, carbon dioxide and nitrogen oxides are hardly generated. Oxygen carrier particles oxidized in the air reactor are separated from the air and then supplied to the fuel reactor. In the fuel reactor, oxygen carrier particles are reduced with fuel. That is, the fuel is oxidized with oxygen carrier particles. Combustion gas such as carbon dioxide is generated in the fuel reactor by reduction of oxygen carrier particles (oxidation of fuel). The oxygen carrier particles reduced in the fuel reactor are returned to the air reactor, oxidized again, and reused.

  As described above, in the chemical loop combustion method, oxygen carrier particles circulating between the air reactor and the fuel reactor mediate oxygen from the air to the fuel. That is, air does not react directly with fuel. Therefore, in the chemical loop combustion method, the exhaust gas generated by the oxidation (combustion) of the fuel does not contain nitrogen derived from air, and the combustion gas such as carbon dioxide can be easily recovered.

Special table 2012-529614 gazette

  A conventional chemical loop combustion apparatus includes a riser as an air reactor. A riser is a pipe or tower extending in the vertical direction. Oxygen carrier particles are introduced into the riser from the bottom of the riser. Oxygen carrier particles in the riser are blown up by the air introduced from the lower part of the riser and move to the upper part of the riser. In the process in which the oxygen carrier particles move to the top of the riser, the oxygen carrier particles are oxidized by oxygen in the air. Oxidized oxygen carrier particles are discharged from the top of the riser along with the remaining air. The oxygen carrier particles are driven by the potential energy and kinetic energy provided by the riser, move from the top of the riser to the fuel reactor, and return from the fuel reactor to the air reactor.

  In order to move the oxygen carrier particles from the lower part of the riser to the upper part of the riser, it is necessary to introduce a high-pressure or high-speed air flow into the riser. As a result, the moving speed of the oxygen carrier particles in the riser is increased, and the residence time of the oxygen carrier particles in the riser is shortened. The residence time is, for example, about several seconds. Therefore, the time allowed for the oxidation reaction of the oxygen carrier particles in the riser is short, and the oxygen carrier particles may not be sufficiently oxidized. If oxygen carrier particles that are not sufficiently oxidized are supplied to the fuel reactor, the oxygen carrier particles are excessively reduced in the fuel reactor. Excessively reduced oxygen carrier particles collapse or adhere to each other. It is difficult to regenerate broken oxygen carrier particles or agglomerated oxygen carrier particles by oxidation in an air reactor.

  As described above, in a conventional chemical loop combustion apparatus including a riser as an air reactor, oxygen carrier particles are consumed due to excessive reduction of oxygen carrier particles.

  The present invention has been made in view of the above circumstances, and an object thereof is to provide a chemical loop combustion apparatus capable of suppressing consumption of oxygen carrier particles and a chemical loop combustion method using the chemical loop combustion apparatus. And

A chemical loop combustion apparatus according to one aspect of the present invention includes an air reactor that forms a first bubble fluidized bed containing oxygen carrier particles and air, and oxidizes the oxygen carrier particles with oxygen in the air in the first bubble fluidized bed. A riser in which oxidized oxygen carrier particles are supplied from an air reactor, and the oxygen carrier particles are moved vertically upward by a carrier gas; and a second bubble flow in which oxygen carrier particles are supplied from the riser and contain oxygen carrier particles and fuel A fuel reactor for reducing oxygen carrier particles with fuel in the second bubble fluidized bed and supplying the reduced oxygen carrier particles to the air reactor; and air in the air reactor as a carrier gas An air transfer line for supplying to the lower part of the air .

  In one aspect of the invention, the oxygen carrier particles are not only oxidized in the riser, but are also oxidized in an air reactor different from the riser. Moreover, since the first bubble fluidized bed is formed in the air reactor, the residence time of the oxygen carrier particles in the air reactor is compared with the residence time of the oxygen carrier particles in the conventional air reactor (riser). Easy to control. Therefore, the residence time of the oxygen carrier particles in the air reactor can be controlled to a time sufficient for the oxidation of the oxygen carrier particles. In other words, according to one aspect of the present invention, it is possible to reduce the amount of oxygen carrier particles discharged from the air reactor in a short time without being sufficiently oxidized. Further, since the second bubble fluidized bed is formed in the fuel reactor, the residence time of the oxygen carrier particles in the fuel reactor is the oxygen in the conventional fuel reactor (for example, moving bed type fuel reactor). It is easier to control than the residence time of the carrier particles. Therefore, the residence time of the oxygen carrier particles in the fuel reactor can be controlled to a time that is necessary for the reduction of the oxygen carrier particles and over-reduction of the oxygen carrier particles is suppressed. In other words, according to one aspect of the present invention, the amount of oxygen carrier particles that stay in the fuel reactor for a long time and are excessively reduced can be reduced as compared with the conventional case. For the above reasons, in one aspect of the present invention, the oxygen carrier particles are prevented from being overreduced, and consumption of oxygen carrier particles due to overreduction is also suppressed. In other words, in one aspect of the present invention, it is easy to balance the residence time of oxygen carrier particles in the air reactor and riser and the residence time of oxygen carrier particles in the fuel reactor. Over-reduction of carrier particles is suppressed.

  A chemical loop combustion apparatus according to one aspect of the present invention is provided with a cyclone in which oxygen carrier particles and a carrier gas are supplied from a riser, the oxygen carrier particles are separated from the carrier gas, and the separated oxygen carrier particles are supplied to a fuel reactor. A powder separator).

  The carrier gas discharged from the riser together with the oxygen carrier particles contains at least nitrogen derived from air. By separating the oxygen carrier particles from the carrier gas using a cyclone, nitrogen in the carrier gas is suppressed from being supplied to the fuel reactor together with the oxygen carrier particles. Therefore, mixing of combustion gas (for example, carbon dioxide) generated in the fuel reactor with nitrogen is also suppressed.

  In the chemical loop combustion apparatus according to one aspect of the present invention, oxygen carrier particles and a carrier gas are supplied from a riser, a part of the oxygen carrier particles is separated from the carrier gas, and the separated oxygen carrier particles are supplied to the fuel reactor. And a cyclone in which the remainder of the oxygen carrier particles and the carrier gas are supplied from the drum, the remainder of the oxygen carrier particles are separated from the carrier gas, and the separated oxygen carrier particles are supplied to the fuel reactor. Good.

  The more oxygen carrier particles that circulate in the chemical loop combustion device, the greater the load on the cyclone. When the load on the cyclone is too large, some oxygen carrier particles are not separated from the carrier gas, and are scattered outside the cyclone together with the carrier gas and are not supplied to the fuel reactor. That is, when the load on the cyclone is too large, oxygen carrier particles are consumed in the cyclone. However, by separating some of the oxygen carrier particles from the carrier gas in the drum and then separating the remainder of the oxygen carrier particles from the carrier gas in the cyclone, the load on the cyclone is reduced, and the scattering of oxygen carrier particles in the cyclone and Consumption is suppressed. That is, the drum can be said to be a powder separator for reducing the load on the cyclone.

  A chemical loop combustion method according to an aspect of the present invention may be a chemical loop combustion method using a chemical loop combustion apparatus including the air transfer line, and the first bubble containing oxygen carrier particles and air in an air reactor. Forming a fluidized bed, oxidizing the oxygen carrier particles with oxygen in the air in the first bubble fluidized bed, supplying the oxidized oxygen carrier particles from the air reactor to the lower part of the riser, and the air reactor Supplying the air inside as a carrier gas to the lower part of the riser through the air transfer line, moving oxygen carrier particles from the lower part of the riser to the upper part of the riser by air, and further oxidizing the oxygen carrier particles by oxygen in the air And supplying further oxidized oxygen carrier particles to the fuel reactor from the top of the riser And forming a second bubble fluidized bed containing oxygen carrier particles and fuel in the fuel reactor, reducing the oxygen carrier particles with the fuel in the second bubble fluidized bed, and reducing the oxygen carrier particles into the fuel. Supplying from the reactor to the air reactor.

  By reusing the air heated in the air reactor as the carrier gas for the riser, energy required for preheating the carrier gas and costs for the carrier gas can be saved.

  ADVANTAGE OF THE INVENTION According to this invention, the chemical loop combustion apparatus which can suppress exhaustion of oxygen carrier particle, and the chemical loop combustion method using the said chemical loop combustion apparatus are provided.

FIG. 1 is a schematic view of a chemical loop combustion apparatus according to an embodiment of the present invention. 2a is a schematic perspective view of the air reactor shown in FIG. 1 and a rectangular first bubble fluidized bed formed in the air reactor, and FIG. 2b is a fuel reactor and fuel reactor shown in FIG. It is a typical perspective view of the rectangular 2nd bubble fluidized bed formed in the inside.

  Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings. In the drawings, the same components are denoted by the same reference numerals. The present invention is not limited to the following embodiment. X, Y, and Z shown in each figure mean three coordinate axes orthogonal to each other. The Y axis faces vertically upward. The X axis and the Z axis are horizontal.

  As shown in FIG. 1, a chemical loop combustion apparatus 100 according to this embodiment includes an air reactor 10, a first line 1, an air transfer line 7, a riser 12, a second line 2, a drum 16, a third line 3, A fourth line 4, a cyclone 18, a fifth line 5, a fuel reactor 14, a sixth line 6, a first seal pot 20a, a second seal pot 20b, and a third seal pot 20c are provided. “Line” means a tube that transports a substance. The positional relationship of the above-described components included in the chemical loop combustion apparatus 100 is as shown in FIG. That is, the air reactor 10 is located above the lower portion 12 b of the riser 12. The upper portion 12 a of the riser 12 is located above the fuel reactor 14. The fuel reactor 14 is located above the air reactor 10. The drum 16 and the cyclone 18 are located above the fuel reactor 14. The first seal pot 20 a is installed in the middle of the first line 1. The second seal pot 20 b is installed in the middle of the sixth line 6. The third seal pot 20 c is installed in the middle of the third line 3.

  The first line 1 connects the lower part of the air reactor 10 and the lower part 12 b of the riser 12. The air transfer line 7 connects the upper part of the air reactor 10 and the lower part 12 b of the riser 12. The second line 2 connects the upper portion 12 a of the riser 12 and the side surface of the drum 16. The third line 3 connects the lower part of the drum 16 and the side surface of the fuel reactor 14. The fourth line 4 connects the upper part of the drum 16 and the side surface of the cyclone 18. The fifth line 5 connects the lower part of the cyclone 18 and the third line 3 located between the drum 16 and the third seal pot 20c. The sixth line 6 connects the side surface of the fuel reactor 14 and the side surface of the air reactor 10. The first seal pot 20 a suppresses the backflow of gas from the riser 12 to the air reactor 10. The second seal pot 20 b suppresses the backflow of gas from the air reactor 10 to the fuel reactor 14. The third seal pot 20 c suppresses the backflow of gas from the fuel reactor 14 to the drum 16 and the cyclone 18.

  The chemical loop combustion method according to the present embodiment is implemented using a chemical loop combustion apparatus 100 as described below.

  Oxygen carrier particles are supplied from the air reactor 10 to the lower part 12b of the riser 12, move from the lower part 12b of the riser 12 to the upper part 12a of the riser 12, and from the upper part 12a of the riser 12 through the drum 16 and the cyclone 18 to the fuel reactor. 14 and supplied from the fuel reactor 14 to the air reactor 10. The oxygen carrier particles supplied from the fuel reactor 14 to the air reactor 10 circulate in the chemical loop combustion apparatus 100 in the above order.

The oxygen carrier particle is a powder containing a single metal or a metal oxide. The composition of the oxygen carrier particles in the reduced state, for example, represented by the general formula MO _x. In the general formula, M is a metal, and x is a real number of 0 or more. The composition of oxygen carrier particles in an oxidized state is represented by, for example, the general formula MO _{x + y} . In the general formula, y is a positive real number. The metal M is not particularly limited, but may be at least one selected from the group consisting of Fe, Ni, Cu, Co, and Mn, for example. The oxygen carrier particles may include a plurality of simple metals. The oxygen carrier particles may include a plurality of metal oxides. The oxygen carrier particles may include a complex oxide (for example, a perovskite oxide) containing a plurality of metals. The oxygen carrier particles may include a metal or metal oxide and a carrier on which the metal or metal oxide is supported. The support is not particularly limited, and examples thereof include Al ₂ O ₃ , ZrO ₂ , TiO ₂ , SiO ₂ , MgO, NiAl ₂ O ₄ , CoAl ₂ O ₄ , YSZ (Ytria-Stabilized Zirconia), CuAl ₂ O _4, and AlPO. It may be at least one selected from the group consisting of ₄ . The oxygen carrier particles may include a plurality of types of carriers. The particle size of the oxygen carrier particles is not particularly limited, but may be, for example, 50 μm or more and 1000 μm or less, or 100 μm or more and 500 μm or less.

  In the air reactor 10, a first bubble fluidized bed containing oxygen carrier particles and air is formed, and the oxygen carrier particles are oxidized by oxygen in the air in the first bubble fluidized bed. Since the oxidation of the oxygen carrier particles is an exothermic reaction, the temperature in the air reactor 10 is maintained at a high temperature by the oxidation of the oxygen carrier particles. Accordingly, the oxygen carrier particles and air in the air reactor 10 are heated at a high temperature. Although the temperature in the air reactor 10 is not specifically limited, For example, it may be 500 degreeC or more and 1200 degrees C or less.

  In general, the “bubble fluidized bed” is a state in which the entire powder (a large number of particles) suspended in a gas behaves as a uniform fluid. When the gravity of the particles balances the force exerted on the particles by the gas flowing vertically upward, the powder is fluidized to form a bubble fluidized bed. Below, based on FIG. 2a, the method of forming the rectangular 1st bubble fluidized bed 22 in the air reactor 10 is demonstrated.

  As shown in FIG. 2a, the air reactor 10 has a rectangular parallelepiped shape, and the space in the air reactor 10 also has a rectangular parallelepiped shape. Of the first side 10a, the second side 10b, and the third side 10c orthogonal to each other in the air reactor 10, the first side 10a is parallel to the X axis. The second side 10b is parallel to the Y axis (vertical direction). The third side 10c is parallel to the Z axis.

  The sixth line 6 extending from the fuel reactor 14 is connected to the side surface of the air reactor 10 to which the second side 10b and the third side 10c belong. The first line 1 is connected to the side surface facing the side surface to which the sixth line 6 is connected. The oxygen carrier particles reduced in the fuel reactor 14 are introduced into the air reactor 10 through the sixth line 6 and discharged out of the air reactor 10 through the first line 1. Therefore, the oxygen carrier particles flow along the X axis or the first side 10a. That is, the oxygen carrier particles flow along the horizontal direction. On the other hand, air (Air) is introduced into the air reactor 10 from the bottom surface of the air reactor 10 and discharged out of the air reactor 10 through the air transfer line 7 connected to the top surface of the air reactor 10. Therefore, air (Air) flows along the vertical direction (Y-axis). Thus, in the air reactor 10, the rectangular 1st bubble fluidized bed 22 is formed by making the flow of an oxygen carrier particle cross or orthogonally cross with the flow of air. “Rectangle” means that the cross section 22a of the first bubble fluidized bed 22 in the direction perpendicular to the flow of oxygen carrier particles is rectangular (square). In other words, the cross section 22a of the first bubble fluidized bed 22 parallel to the vertical direction (Y-axis direction) is rectangular. The height of the first bubble fluidized bed 22 in the vertical direction (Y-axis direction) is substantially constant.

  The entire rectangular first bubble fluidized bed 22 behaves as a laminar flow rather than a turbulent flow. Accordingly, the individual oxygen carrier particles contained in the rectangular first bubble fluidized bed 22 are easily moved together in the air reactor 10. In other words, the individual oxygen carrier particles contained in the rectangular first bubble fluidized bed 22 easily move in substantially the same direction at substantially the same speed. Therefore, it is easy to control the residence time of the oxygen carrier particles in the air reactor 10, and the variation in the residence time of the oxygen carrier particles tends to be small. As a result, it is easy to control the residence time to a time sufficient for the oxidation reaction of the oxygen carrier particles. That is, it is easy to reduce the amount of oxygen carrier particles discharged from the air reactor 10 in a short time without being sufficiently oxidized. Moreover, since the inside of the 1st bubble fluidized bed 22 is disturbed by the bubble of air, the temperature of the 1st bubble fluidized bed 22 is easy to be maintained uniformly. Therefore, the oxygen carrier particles in the first bubble fluidized bed 22 are easily oxidized without spots.

  If the oxygen carrier particles are lowered from the upper part of the air reactor 10, the air is caused to flow vertically upward from the lower part of the air reactor 10, and the gravity of the oxygen carrier particles is larger than the force exerted by the air on the oxygen carrier particles. In the air reactor 10, not the bubble fluidized bed but the moving bed is easily formed. Further, if oxygen carrier particles and air are allowed to flow vertically upward from the lower part of the air reactor 10 and the gravity of the oxygen carrier particles is smaller than the force exerted on the oxygen carrier particles, the air reactor 10 has a rectangular shape. It is easy to form a turbulent flow rather than a bubble fluidized bed (laminar flow). In the moving bed or turbulent flow, the oxygen carrier particles are unlikely to behave as a uniform fluid. Therefore, the individual oxygen carrier particles included in the moving bed or turbulent flow are difficult to move in substantially the same direction at substantially the same speed. In other words, the individual oxygen carrier particles contained in the moving bed or turbulent flow are difficult to move together in the air reactor 10. Therefore, it is difficult to control the residence time of the oxygen carrier particles in the air reactor 10, and the variation in the residence time of the oxygen carrier particles tends to increase. As a result, it is difficult to control the residence time to a time sufficient for the oxidation reaction of the oxygen carrier particles. That is, it is difficult to reduce the amount of oxygen carrier particles discharged from the air reactor 10 in a short time without being sufficiently oxidized.

  The superficial velocity of air (Air) in the air reactor 10 only needs to be greater than the bubble fluidization start rate (bubble start rate) and may be less than the terminal velocity of the oxygen carrier particles. The bubble fluidization start speed and end speed vary depending on the shape of the oxygen carrier particles, the average particle size and the particle size distribution, and the shape of the air reactor 10, and are determined experimentally. What is necessary is just to design the air reactor 10 and oxygen carrier particle so that the optimal flow state in the air reactor 10 is acquired on the operating conditions requested | required of the chemical loop combustion apparatus 100. FIG.

  The average value of the residence time of the oxygen carrier particles in the air reactor 10 is estimated by, for example, dividing the volume of the air reactor 10 by the particle circulation rate. Alternatively, the average value of the residence time of the oxygen carrier particles may be calculated by dividing the volume of the flow path of the oxygen carrier particles in the air reactor 10 by the particle circulation amount. The residence time of the oxygen carrier particles in the air reactor 10 may be controlled by adjusting the particle circulation amount. The particle circulation amount is the circulation speed of the oxygen carrier particles in the chemical loop combustion apparatus 100. The particle circulation amount is paraphrased as the amount (for example, volume) of oxygen carrier particles supplied into the air reactor 10 per unit time or the amount of oxygen carrier particles discharged from the air reactor 10 per unit time. May be.

  The moving speed of the first bubble fluidized bed 22 (oxygen carrier particles) in the air reactor 10 is calculated, for example, by dividing the particle circulation amount by the cross-sectional area of the flow path of oxygen carrier particles in the air reactor 10. The The cross-sectional area of the flow path is, for example, the area of the cross-section 22a of the first bubble fluidized bed 22 in the direction perpendicular to the flow of oxygen carrier particles. The cross-sectional area of the flow path depends on the dimensions of the air reactor 10. For example, the width of the flow path depends on the length of the third side 10 c of the air reactor 10. The height of the flow path is equal to or less than the length of the second side 10 b of the air reactor 10. From the above, the moving speed of the first bubble fluidized bed 22 in the air reactor 10 is set to a desired value by adjusting the particle circulation amount or setting the dimensions of the air reactor 10 at the design stage. . By appropriately setting the moving speed of the first bubble fluidized bed 22 in the air reactor 10 according to the type of oxygen carrier particles, a rectangular first bubble fluidized bed 22 that behaves as a laminar flow is easily formed.

  Oxygen carrier particles oxidized in the air reactor 10 are supplied from the air reactor 10 to the lower portion 12 b of the riser 12 through the first line 1. The air in the air reactor 10 is supplied to the lower part 12b of the riser 12 through the air transfer line 7 as carrier gas. The oxygen carrier particles in the air reactor 10 are blown off by the air supplied from the air transfer line 7 and moved from the lower part 12 b of the riser 12 to the upper part 12 a of the riser 12. That is, the oxygen carrier particles are moved vertically upward by the upward flow of air. As a result, potential energy and kinetic energy are imparted to the oxygen carrier particles. The oxygen carrier particles are driven by the energy applied in the riser 12 and circulate in the chemical loop combustion apparatus 100. By adjusting the volume flow rate of the air supplied into the riser 12 (the superficial velocity of the carrier gas in the riser 12), the amount of particle circulation can be controlled. Further, by adjusting the total amount of oxygen carrier particles circulating in the chemical loop combustion apparatus 100, the particle circulation amount can be controlled. The amount of particle circulation in the chemical loop combustion apparatus 100 may be substantially constant.

  In the process in which the oxygen carrier particles move to the upper portion 12a of the riser 12, the oxygen carrier particles are further oxidized by oxygen in the air. By oxidizing the oxygen carrier particles in both the air reactor 10 and the riser 12, the overreduction of the oxygen carrier particles in the fuel reactor 14 is suppressed. By reusing the air heated in the air reactor 10 as the carrier gas for the riser 12, energy required for preheating the carrier gas and costs for the carrier gas can be saved.

  Oxygen carrier particles oxidized in the riser 12 are supplied to the drum 16 from the upper portion 12a of the riser 12 through the second line 2 together with air (carrier gas). The drum 16 is a container in which oxygen carrier particles and air temporarily stay. The lower portion of the drum 16 may have an inverted conical shape, for example, like the cyclone 18. The lower part of the drum 16 may be an end plate. The drum 16 has a function of separating powder from gas by the same principle (centrifugation) as the cyclone 18. In the drum 16, some of the oxygen carrier particles are separated from the air, and the separated oxygen carrier particles are supplied to the fuel reactor 14 through the third line 3. The remainder of the oxygen carrier particles and air are discharged from the drum 16 and supplied to the cyclone 18 through the fourth line 4. In the cyclone 18, the remaining oxygen carrier particles are separated from the air, and the separated oxygen carrier particles are supplied to the fuel reactor 14 through the fifth line 5 and the third line 3. Air (nitrogen and oxygen) separated from the oxygen carrier particles in the cyclone 18 is exhausted from the top of the cyclone 18.

  By separating the oxygen carrier particles from the air using the drum 16 and the cyclone 18, the nitrogen in the air (carrier gas) is suppressed from being supplied to the fuel reactor 14 together with the oxygen carrier particles. Therefore, mixing of the gas produced in the fuel reactor 14 with nitrogen is also suppressed.

  After separating some of the oxygen carrier particles from the air in the drum 16 and then separating the remainder of the oxygen carrier particles from the air in the cyclone 18, the load on the cyclone 18 is reduced, and the scattering of oxygen carrier particles in the cyclone 18 and Consumption is suppressed.

  In the fuel reactor 14, a second bubble fluidized bed is formed from the oxygen carrier particles, the fuel, and the fluidized gas G. In the second bubble fluidized bed, the oxygen carrier particles are reduced by the fuel. That is, the fuel is oxidized with oxygen contained in the oxygen carrier particles. The temperature in the fuel reactor 14 depends on the temperature of the oxygen carrier particles heated by the oxidation reaction in the air reactor 10 and the riser 12. The temperature in the fuel reactor 14 also depends on the reaction heat of the oxygen carrier particle reduction reaction (fuel oxidation reaction) in the fuel reactor 14. Although the temperature in the fuel reactor 14 is not specifically limited, For example, it may be 500 degreeC or more and 1200 degrees C or less.

  The fuel contains carbon. The fuel may be a gaseous fuel or a solid fuel S, for example. The gaseous fuel may be at least one selected from the group consisting of methane, propane, butane, natural gas, and coal gasification gas, for example. The solid fuel S may be at least one selected from the group consisting of coal, coke (hard coal), plastic, and biomass fuel, for example. The solid fuel S may be a powder. Multiple types of fuels may be used. The fluidizing gas G is a gas that does not contain nitrogen. The fluidizing gas G may be at least one selected from the group consisting of water vapor, carbon dioxide, and oxygen, for example. A plurality of types of fluidized gases G may be used. Gaseous fuel may be used as the fluidizing gas G. A fluidizing gas G containing a hydrocarbon gas such as methane and water vapor is supplied to the fuel reactor 14, and a partial oxidation reaction, a water vapor reforming reaction and a water gas shift reaction of the hydrocarbon gas are advanced, and carbon monoxide and hydrogen are produced. Syngas containing may be generated. The fuel may be completely oxidized in the fuel reactor 14 to produce a gas containing carbon dioxide and water.

  Hereinafter, a method of forming the rectangular second bubble fluidized bed 24 in the fuel reactor 14 will be described with reference to FIG. For convenience of explanation, a case where gaseous fuel is used as the fluidizing gas G will be described below.

  As shown in FIG. 2b, the fuel reactor 14 has a rectangular parallelepiped shape, and the space in the fuel reactor 14 also has a rectangular parallelepiped shape. Of the first side 14a, the second side 14b, and the third side 14c orthogonal to each other in the fuel reactor 14, the first side 14a is parallel to the X axis. The second side 14b is parallel to the Y axis (vertical direction). The third side 14c is parallel to the Z axis.

  The third line 3 extending from the drum 16 is connected to the side surface of the fuel reactor 14 to which the second side 14b and the third side 14c belong. The sixth line 6 is connected to the side surface opposite to the side surface to which the third line 3 is connected. Oxygen carrier particles oxidized in the air reactor 10 and the riser 12 are introduced into the fuel reactor 14 through the third line 3 and discharged out of the fuel reactor 14 through the sixth line 6. Accordingly, the oxygen carrier particles flow along the X axis or the first side 14a. That is, the oxygen carrier particles flow along the horizontal direction. On the other hand, the fluidizing gas G is introduced into the fuel reactor 14 from the bottom surface of the fuel reactor 14, and discharged from the fuel reactor 14 to the outside of the fuel reactor 14. Therefore, the fluidizing gas G flows along the vertical direction (Y axis). Thus, the rectangular second bubble fluidized bed 24 is formed by intersecting or orthogonally crossing the flow of the oxygen carrier particles with the flow of the fluidizing gas G in the fuel reactor 14. “Rectangle” means that the cross section 24a of the second bubble fluidized bed 24 in the direction perpendicular to the flow of oxygen carrier particles is rectangular (quadrangle). In other words, the cross section 24a of the second bubbling fluidized bed 24 parallel to the vertical direction (Y-axis direction) is rectangular. The height of the second bubble fluidized bed 24 in the vertical direction (Y-axis direction) is substantially constant.

  The entire rectangular second bubble fluidized bed 24 behaves as a laminar flow rather than a turbulent flow. Therefore, the individual oxygen carrier particles contained in the rectangular second bubble fluidized bed 24 are easily moved together in the fuel reactor 14. In other words, the individual oxygen carrier particles contained in the rectangular second bubble fluidized bed 24 easily move in substantially the same direction at substantially the same speed. Therefore, it is easy to control the residence time of the oxygen carrier particles in the fuel reactor 14, and the dispersion of the residence time of the oxygen carrier particles tends to be small. As a result, it is easy to control the residence time of the oxygen carrier particles in the fuel reactor 14 to a time that is necessary for the reduction of the oxygen carrier particles and the overreduction of the oxygen carrier particles is suppressed. That is, it is easy to reduce the amount of oxygen carrier particles that stay in the fuel reactor 14 for a long time and are excessively reduced. Further, since the inside of the second bubble fluidized bed 24 is disturbed by the bubbles of the fluidized gas G, the temperature in the second bubble fluidized bed 24 is easily maintained uniformly. Therefore, the temperature of the second bubble fluidized bed 24 is not likely to be locally high, and the overreduction of oxygen carrier particles at high temperatures is likely to be suppressed.

  Temporarily, the oxygen carrier particles are lowered from the upper part of the fuel reactor 14, the fluidizing gas G is caused to flow vertically upward from the lower part of the fuel reactor 14, and the gravity of the oxygen carrier particles causes the fluidizing gas G to be oxygen carrier particles. When the force exerted on the fuel is larger than that, a moving bed is easily formed in the fuel reactor 14 instead of the bubble fluidized bed. If oxygen carrier particles and fluidized gas G are allowed to flow vertically upward from the lower part of the fuel reactor 14 and the gravity of the oxygen carrier particles is smaller than the force exerted by the fluidized gas G on the oxygen carrier particles, the fuel reaction In the vessel 14, a turbulent flow is easily formed instead of a rectangular bubble fluidized bed (laminar flow). In the moving bed or turbulent flow, the oxygen carrier particles are unlikely to behave as a uniform fluid. Therefore, the individual oxygen carrier particles included in the moving bed or turbulent flow are difficult to move in substantially the same direction at substantially the same speed. In other words, the individual oxygen carrier particles contained in the moving bed or turbulent flow are difficult to move together in the fuel reactor 14. Therefore, it is difficult to control the residence time of the oxygen carrier particles in the fuel reactor 14, and the dispersion of the residence time of the oxygen carrier particles tends to increase. As a result, it is difficult to control the residence time of the oxygen carrier particles in the fuel reactor 14 to a time that is necessary for the reduction of the oxygen carrier particles and that the excessive reduction of the oxygen carrier particles is suppressed. That is, it is difficult to reduce the amount of oxygen carrier particles that stay in the fuel reactor 14 for a long time and are excessively reduced.

  The superficial velocity of the fluidizing gas G in the fuel reactor 14 may be larger than the bubble fluidization start velocity (bubble initiation velocity) and may be less than the terminal velocity of the oxygen carrier particles. The bubble fluidization start speed and the end speed vary depending on the shape of the oxygen carrier particles, the average particle size and the particle size distribution, and the shape of the fuel reactor 14, and are determined experimentally. What is necessary is just to design the fuel reactor 14 and oxygen carrier particle so that the optimal flow state in the fuel reactor 14 may be obtained under the operating conditions required for the chemical loop combustion apparatus 100.

  The average value of the residence time of the oxygen carrier particles in the fuel reactor 14 is approximated by, for example, dividing the volume of the fuel reactor 14 by the particle circulation rate. Alternatively, the average value of the residence time of the oxygen carrier particles may be calculated by dividing the volume of the flow path of the oxygen carrier particles in the fuel reactor 14 by the particle circulation amount. The residence time of the oxygen carrier particles in the fuel reactor 14 may be controlled by adjusting the particle circulation amount. The particle circulation amount is the amount (for example, volume) of oxygen carrier particles supplied into the fuel reactor 14 per unit time, or the amount of oxygen carrier particles discharged from the fuel reactor 14 per unit time. It may be paraphrased.

  The moving speed of the second bubble fluidized bed 24 (oxygen carrier particles) in the fuel reactor 14 is calculated by, for example, dividing the particle circulation amount by the cross-sectional area of the flow path of oxygen carrier particles in the fuel reactor 14. The The cross-sectional area of the channel is, for example, the area of the cross section 24a of the second bubble fluidized bed 24 in the direction perpendicular to the flow of oxygen carrier particles. The cross-sectional area of the flow path depends on the dimensions of the fuel reactor 14. For example, the width of the flow path depends on the length of the third side 14 c of the fuel reactor 14. The height of the flow path is equal to or less than the length of the second side 14 b of the fuel reactor 14. From the above, the moving speed of the second bubble fluidized bed 24 in the fuel reactor 14 is set to a desired value by adjusting the particle circulation amount or setting the dimensions of the fuel reactor 14 at the design stage. . By appropriately setting the moving speed of the second bubble fluidized bed 24 in the fuel reactor 14 according to the type of oxygen carrier particles, a rectangular second bubble fluidized bed 24 that behaves as a laminar flow is easily formed.

  When the solid fuel S is used, the solid fuel S may be supplied into the fuel reactor 14 from the side surface to which the second side 14b and the third side 14c belong, similarly to the oxygen carrier particles supplied from the third line 3. . When the solid fuel S is used, the second bubble fluidized bed 24 may be controlled based not only on the particle circulation rate and the superficial velocity of the fluidized gas G but also on the supply speed of the solid fuel S to the fuel reactor 14. .

  The oxygen carrier particles reduced in the fuel reactor 14 are supplied from the fuel reactor 14 to the air reactor 10 through the sixth line 6. In the air reactor 10, the oxygen carrier particles are again oxidized with oxygen in the air.

  Electric power may be generated by supplying high-temperature and high-pressure air separated from oxygen carrier particles in the cyclone 18 to the gas turbine, driving the gas turbine with the air, and driving the generator with the gas turbine. The air separated in the cyclone 18 may be supplied to the heat exchanger, and the water may be heated with air in the heat exchanger to generate high-temperature and high-pressure steam. Electric power may be generated by supplying the steam to the steam turbine, driving the steam turbine with the steam, and driving the generator with the steam turbine. Even if the air separated in the cyclone 18 is supplied to the heat exchanger and the fluidized gas G before being supplied to the air reactor 10 or the fluidized gas G before being supplied to the fuel reactor 14 is preheated in the heat exchanger. Good.

  High purity nitrogen may be purified by separating and removing components other than nitrogen from the air separated in the cyclone 18. High purity nitrogen is used, for example, in the chemical industry, the electrical machinery industry, or the steel industry.

  The product gas in the fuel reactor 14 may be supplied to a heat exchanger, and water may be heated with the product gas in the heat exchanger to generate high-temperature and high-pressure steam. Electric power may be generated by supplying the steam to the steam turbine, driving the steam turbine with the steam, and driving the generator with the steam turbine. The product gas in the fuel reactor 14 is supplied to a heat exchanger, and in the heat exchanger, air before being supplied to the air reactor 10 or fluidized gas G before being supplied to the fuel reactor 14 is preheated. Also good.

  When synthesis gas is generated in the fuel reactor 14, the synthesis gas is used as a raw material for a chemical plant, for example. When the product gas in the fuel reactor 14 contains carbon dioxide as a main component, high purity carbon dioxide may be purified by separating and removing components other than carbon dioxide (for example, water) from the product gas. High-purity carbon dioxide is used, for example, as a gas for arc welding, a raw material for carbonated beverages, a coolant, a supercritical fluid for industrial processes, or a raw material for chemical products.

  As mentioned above, although embodiment of this invention was described, this invention is not limited to said embodiment.

  For example, the chemical loop combustion apparatus 100 may not include the air transfer line 7. When there is no air transfer line 7, a carrier gas containing oxygen is supplied from the lower part 12 b of the riser 12 into the riser 12. The carrier gas containing oxygen may be air other than the air supplied to the air reactor 10, for example. The carrier gas containing oxygen may be a mixture of oxygen and an inert gas. You may supply the air discharged | emitted from the cyclone 18 to the riser 12 as carrier gas. When there is no air transfer line 7, the air in the air reactor 10 may be discharged from the upper part of the air reactor 10.

  The chemical loop combustion apparatus 100 may not include the drum 16. In this case, oxygen carrier particles and air (carrier gas) in the riser 12 are directly supplied to the cyclone 18. Oxygen carrier particles separated from air (carrier gas) by the cyclone 18 are directly supplied to the fuel reactor 14.

  When the chemical loop combustion apparatus 100 does not include the drum 16, the chemical loop combustion apparatus 100 may include a plurality of cyclones. In this case, oxygen carrier particles and air (carrier gas) are supplied directly from the upper portion 12a of the riser 12 to the cyclone 18. In the cyclone 18, some of the oxygen carrier particles are separated from the air (carrier gas), and the separated oxygen carrier particles are supplied to the fuel reactor 14. The remainder of the oxygen carrier particles and air (carrier gas) are supplied from the cyclone 18 to another cyclone. In another cyclone, the remainder of the oxygen carrier particles is separated from the air (carrier gas) and the separated oxygen carrier particles are supplied to the fuel reactor 14.

  The shape of the air reactor 10 is not limited to a rectangular parallelepiped. In order to form the rectangular first bubble fluidized bed 22, the air reactor 10 only needs to include a flow path (space) having a rectangular cross section in a direction perpendicular to the flow of oxygen carrier particles. The shape of the fuel reactor 14 is not limited to a rectangular parallelepiped. In order to form the rectangular second bubble fluidized bed 24, the fuel reactor 14 only needs to include a flow path (space) having a rectangular cross section in a direction perpendicular to the flow of oxygen carrier particles. The flow path of the oxygen carrier particles in the air reactor 10 or the fuel reactor 14 may not be linear, and may be bent or bent. For example, the shape of the channel viewed from above is C-shaped, J-shaped, L-shaped, M-shaped, N-shaped, S-shaped, T-shaped, U-shaped, V-shaped, W It may be letter-shaped or Z-shaped.

  The first bubble fluidized bed may not be rectangular. For example, the air reactor 10 may have a tubular or tower shape extending in the vertical direction, and the air reactor 10 may form a circular first bubble fluidized bed. The second bubble fluidized bed may not be rectangular. For example, the fuel reactor 14 may have a tubular or tower shape extending in the vertical direction, and a circular second bubble fluidized bed may be formed in the fuel reactor 14. “Circular” means that the cross section of the bubble fluidized bed in a direction perpendicular to the flow of oxygen carrier particles is circular. However, the flow state of the circular bubble fluidized bed is more complicated than that of the rectangular bubble fluidized bed. Therefore, the residence time of the oxygen carrier particles in the reactor forming the rectangular bubble fluidized bed is easier to control than the residence time of the oxygen carrier particles in the reactor forming the circular bubble fluidized bed.

  The chemical loop combustion apparatus and the chemical loop combustion method according to the present invention are applied to, for example, production of synthesis gas using fossil fuel or power generation using fossil fuel.

DESCRIPTION OF SYMBOLS 1 1st line 2 2nd line 3 3rd line 4 4th line 5 5th line 6 6th line 7 Air transfer line 10 Air reactor 10a First side 10b of an air reactor Second side 10c of an air reactor Air Third side of reactor 12 Riser 12a Upper part of riser 12b Lower part of riser 14 Fuel reactor 14a First side of fuel reactor 14b Second side of fuel reactor 14c Third side of fuel reactor 16 Drum 18 Cyclone 20a First One seal pot 20b Second seal pot 20c Third seal pot 22 First bubble fluidized bed 22a Section 24 of the first bubble fluidized bed Second bubble fluidized bed 24a Section of the second bubble fluidized bed 100 Chemical loop combustion device Air Air G Flow Gas S solid fuel

Claims (4)

Forming an air bubble fluidized bed containing oxygen carrier particles and air, and oxidizing the oxygen carrier particles with oxygen in the air in the air bubble fluidized bed;
A riser for supplying the oxidized oxygen carrier particles from the air reactor, and moving the oxygen carrier particles vertically upward by a carrier gas;
The oxygen carrier particles are supplied from the riser to form a second bubble fluidized bed containing the oxygen carrier particles and fuel, and the oxygen carrier particles are reduced by the fuel in the second bubble fluidized bed and reduced. A fuel reactor for supplying oxygen carrier particles to the air reactor;
An air transfer line for supplying the air in the air reactor to the lower part of the riser as the carrier gas;
Comprising
Chemical loop combustion device. The apparatus further comprises a cyclone in which the oxygen carrier particles and the carrier gas are supplied from the riser, the oxygen carrier particles are separated from the carrier gas, and the separated oxygen carrier particles are supplied to the fuel reactor.
The chemical loop combustion apparatus according to claim 1. A drum in which the oxygen carrier particles and the carrier gas are supplied from the riser, a part of the oxygen carrier particles is separated from the carrier gas, and the separated oxygen carrier particles are supplied to the fuel reactor;
A cyclone in which the remainder of the oxygen carrier particles and the carrier gas are supplied from the drum, the remainder of the oxygen carrier particles are separated from the carrier gas, and the separated oxygen carrier particles are supplied to the fuel reactor;
Further comprising
The chemical loop combustion apparatus according to claim 1. A chemical loop combustion method using the chemical loop combustion apparatus according to any one of claims 1 to 3 ,
Forming the first bubble fluidized bed containing the oxygen carrier particles and the air in the air reactor, and oxidizing the oxygen carrier particles with the oxygen in the air in the first bubble fluidized bed;
Supplying the oxidized oxygen carrier particles from the air reactor to a lower portion of the riser;
Supplying the air in the air reactor as the carrier gas to the lower part of the riser through the air transfer line;
Moving the oxygen carrier particles from the lower part of the riser to the upper part of the riser by the air, and further oxidizing the oxygen carrier particles by oxygen in the air;
Further supplying the oxidized oxygen carrier particles from the top of the riser to the fuel reactor;
Forming the second bubble fluidized bed containing the oxygen carrier particles and the fuel in the fuel reactor, and reducing the oxygen carrier particles with the fuel in the second bubble fluidized bed;
Supplying the reduced oxygen carrier particles from the fuel reactor to the air reactor;
Comprising
Chemical loop combustion method.

Images