Natural gas chemical looping combustion system

Abstract

The utility model discloses a natural gas chemical looping combustion system which is characterized in that a reduction-state oxygen carrier in the system is in direct contact with air in an air reactor, the oxygen carrier is oxidized, and after the oxidation-state oxygen carrier and the air enter a cyclone separator to be separated, the oxygen carrier is conveyed to a fuel reactor to be mixed with gas fuel; sufficient combustion of gas fuel is achieved, high-temperature flue gas full of water vapor and CO2 is generated, and the high-temperature flue gas carries a reduction-state oxygen carrier to enter a separator. After passing through the separator, the oxygen carrier is captured and returned to the fuel reactor and is conveyed back to the air reactor through the controllable valve for the next circulation, and the high-temperature flue gas enters a flue gas treatment system. Part of the high-temperature flue gas enters the material returning device and the controllable valve through the circulating fan to be subjected to material fluidization, so that energy consumption is reduced, water vapor contained in the rest high-temperature flue gas is condensed through heat exchange cooling, high-purity CO2 gas is obtained, and efficient combustion of gas fuel and efficient separation of CO2 are achieved.

Description

Technical Field

[0001] The utility model belongs to the technical field of boiler manufacturing and transformation, and particularly relates to a natural gas chemical chain combustion system. Background Art

[0002] Chemical Looping Combustion is a new type of clean, low-carbon, safe and efficient CO 2 Separation combustion technology usually consists of an air reactor and a fuel reactor. The basic principle of chemical chain combustion is to decompose the traditional combustion reaction of direct contact between fuel and air into two redox reactions with the help of oxygen carriers. Through the cyclic oxidation-reduction of the oxygen carrier between the two reactors, heat and oxygen in the air are transferred from the air reactor to the fuel reactor, avoiding direct contact between fuel and air. Therefore, chemical chain combustion technology has the advantages of separating CO 2 The characteristics of carbon capture have significant advantages in the field of carbon capture.

[0003] Chemical chain combustion technology can reduce carbon emissions from fossil fuel combustion. For gas fuels such as natural gas, current gas boilers have NOx emissions that are difficult to meet standards, low energy efficiency, and CO 2 The chemical looping combustion technology can separate the natural gas combustion reaction into oxidation-reduction reactions in the air reactor and the fuel reactor, which can greatly reduce CO 2 Capture costs.

[0004] In gas boilers, direct contact combustion of natural gas and air results in NOx emissions that are difficult to meet standards, low energy efficiency, and CO 2 The capture cost is high. Utility Model Content

[0005] The utility model aims to overcome the problems of the prior art and discloses a natural gas chemical chain combustion system. Through the structural setting of the system of the utility model, the reduced oxygen carrier is oxidized in the air reactor, and after being separated by the cyclone separator, the oxidized oxygen carrier is transported to the fuel reactor to react with the gas fuel to generate saturated water vapor and CO 2 The high-temperature flue gas carries the reduced oxygen carrier into the cyclone separator for gas-solid separation. The oxygen carrier returns to the fuel reactor, and the high-temperature flue gas enters the flue gas treatment system. The high-temperature flue gas condenses the water vapor contained in it through heat exchange cooling to obtain high-purity CO 2 gas, ultimately achieving efficient combustion of gas fuel and CO 2 Efficient separation.

[0006] The purpose of the utility model is achieved through the following technical solutions:

[0007] A natural gas chemical chain combustion system, comprising: an air reactor, a fuel reactor, an AR cyclone separator, a FR cyclone separator, a splitter return device and a return device;

[0008] The top of the air reactor is connected to the AR cyclone separator via a pipeline. The air reactor is configured to: complete an oxidation reaction based on the received oxygen carrier and air, and the generated oxidized oxygen carrier is transported to the AR cyclone separator driven by the flue gas.

[0009] The AR cyclone separator has a downcomer at the bottom end thereof connected to a flow divider and return device, and the flow divider and return device is connected to a fuel reactor. The AR cyclone separator is configured to complete gas-solid separation of the received material, and input the oxidized oxygen carrier into the flow divider and return device, and the flow divider and return device inputs the oxidized oxygen carrier into the fuel reactor;

[0010] The top of the fuel reactor is provided with a pipeline connected to the FR cyclone separator. The fuel reactor completes the redox reaction based on the received oxidized oxygen carrier and natural gas to generate water vapor and CO 2 The fuel reactor flue gas and reduced oxygen carrier are input to the FR cyclone separator;

[0011] The bottom end of the FR cyclone separator is provided with a downcomer connected to a returner, and the bottom end of the returner is provided with a pipeline connected to a fuel reactor. The FR cyclone separator performs gas-solid separation on the received material, and transports the reduced oxygen carrier particles obtained by separation to the fuel reactor through the returner;

[0012] The bottom end of the fuel reactor is provided with a pipeline connected to the air reactor for transporting the reduced oxygen carrier back to the air reactor.

[0013] According to a preferred embodiment, the AR cyclone separator is externally connected to an AR flue gas treatment system for treating the flue gas separated by the AR cyclone separator.

[0014] According to a preferred embodiment, the split flow return device is further provided with a pipeline connected to the air reactor for refluxing the partially oxidized oxygen carrier to the air reactor.

[0015] According to a preferred embodiment, a controllable valve is provided on the connecting pipe between the fuel reactor and the air reactor.

[0016] According to a preferred embodiment, the FR cyclone separator is externally connected to a FR flue gas treatment system for treating the flue gas separated by the FR cyclone separator.

[0017] According to a preferred embodiment, a flue gas recirculation system is provided downstream of the FR flue gas treatment system, and is connected to the diverter return device, the return device, and the controllable valve respectively through the flue gas recirculation system.

[0018] According to a preferred embodiment, the splitter and returner are fluidized bed equipment, and the fluidizing gas is recycled flue gas. The recycled flue gas temperature is higher than 150°C.

[0019] According to a preferred embodiment, the air reactor adopts a circulating fluidized bed device, the fluidized material and reaction gas inside the air reactor is air, and the corresponding air is provided by an external air supply system. The reaction temperature in the air reactor is about 1015°C, and the fluidized gas velocity is 5-9m / s.

[0020] According to a preferred embodiment, the fuel reactor adopts a circulating fluidized bed device, and the fluidized material and reaction gas inside the fuel reactor are natural gas and CO generated by the reaction. 2 +H 2 O. The reaction temperature in the fuel reactor is about 950°C, and the fluidizing gas velocity is 0.3-1.0 m / s.

[0021] According to a preferred embodiment, the oxygen carrier is a metal oxide, including Ni, Fe, Cu, Co, Mn and composite metal oxides thereof.

[0022] The above-mentioned main scheme of the utility model and its further optional schemes can be freely combined to form multiple schemes, all of which are schemes that can be adopted and claimed for protection by the utility model. After understanding the scheme of the utility model, those skilled in the art can understand that there are many combinations based on the existing technology and common knowledge, all of which are technical schemes to be protected by the utility model, and they are not exhaustively listed here.

[0023] Beneficial effects of the utility model:

[0024] At present, conventional gas boilers have problems such as NOx emissions that are difficult to meet standards, low energy efficiency, and CO 2 The capture cost is high. This is because the direct mixing of natural gas and air leads to the generation of thermal NOx and rapid NOx. The CO in the flue gas produced by natural gas combustion 2 This is due to the low content and the inability to utilize the latent heat in the water vapor.

[0025] In order to overcome the above problems, the utility model discloses a natural gas chemical chain combustion system, which utilizes the characteristics of chemical chain combustion to avoid direct contact between natural gas and air, improve the energy utilization efficiency of natural gas, and reduce CO 2 The capture costs are as follows:

[0026] The fuel reactor adopts a circulating fluidized bed form, which can achieve full contact between natural gas and oxygen carrier, and improve heat and mass transfer efficiency and reaction rate.

[0027] The FR cyclone separator is used to receive high-temperature flue gas and reduced oxygen carriers from the fuel reactor. Through its own efficient gas-solid separation characteristics, the high-temperature flue gas enters the FR flue gas treatment system through the central tube, and the reduced oxygen carrier enters the return device through the downcomer.

[0028] The return device is used to receive the reduced oxygen carrier captured by the FR cyclone separator and transport the reduced oxygen carrier back to the fuel reactor.

[0029] The reduced oxygen carrier in the fuel reactor is transported to the air reactor via a controllable valve, and the circulating flow of the oxygen carrier is effectively controlled by controlling the recirculating flue gas flow of the controllable valve.

[0030] The air reactor is used to receive the reduced oxygen carrier from the controllable valve and fully mix it with the fresh oxygen carrier and the air to carry out a full oxidation reaction.

[0031] The AR cyclone separator is used to receive the oxidized oxygen carrier and high-temperature flue gas in the air reactor. Through its own efficient gas-solid separation characteristics, the high-temperature flue gas enters the AR flue gas treatment system through the central tube, and the oxidized oxygen carrier enters the diversion return device through the downcomer.

[0032] The split return feeder is used to receive the oxidized oxygen carrier captured by the AR cyclone separator, and transport a part of the oxidized oxygen carrier back to the air reactor, and transport the other part of the oxidized oxygen carrier to the fuel reactor to fully contact and react with the natural gas. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 It is a structural schematic diagram of the utility model system.

[0034] Among them, 1-air reactor, 2-fuel reactor, 3-AR cyclone separator, 4-FR cyclone separator, 5-diverter return device, 6-return device, 7-controllable valve, 8-oxygen carrier feeding system, 9-air supply system, 10-natural gas supply system, 11-air reactor flue gas, 12-fuel reactor flue gas, 13-flue gas recirculation system, 14-AR flue gas treatment system, 15-FR flue gas treatment system. DETAILED DESCRIPTION

[0035] The following describes the implementation of the present invention through specific examples, and those skilled in the art can easily understand other advantages and effects of the present invention from the contents disclosed in this specification. The present invention can also be implemented or applied through other different specific implementations, and the details in this specification can also be modified or changed in various ways based on different viewpoints and applications without departing from the spirit of the present invention. It should be noted that the following embodiments and features in the embodiments can be combined with each other without conflict.

[0036] It should be noted that similar reference numerals and letters denote similar items in the following drawings, and therefore, once an item is defined in one drawing, further definition and explanation thereof is not required in subsequent drawings.

[0037] In the description of the present utility model, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inside", "outside", etc. indicate the orientation or position relationship based on the orientation or position relationship shown in the accompanying drawings, or the orientation or position relationship in which the utility model product is usually placed when in use, which is only for the convenience of describing the utility model and simplifying the description, and does not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present utility model. In addition, the terms "first", "second", "third", etc. are only used to distinguish the description, and cannot be understood as indicating or implying relative importance.

[0038] In addition, the terms "horizontal", "vertical", "overhanging" and the like do not mean that the components are required to be absolutely horizontal or overhanging, but can be slightly tilted. For example, "horizontal" only means that its direction is more horizontal than "vertical", and does not mean that the structure must be completely horizontal, but can be slightly tilted.

[0039] In the description of the present invention, it is also necessary to explain that, unless otherwise clearly specified and limited, the terms "set", "install", "connect", and "connect" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0040] In addition, the present utility model should point out that, in the present utility model, if the specific structure, connection relationship, position relationship, power source relationship, etc. are not specifically written out, the structure, connection relationship, position relationship, power source relationship, etc. involved in the present utility model are all known by technical personnel in this field on the basis of existing technology without creative work.

[0041] Embodiment 1:

[0042] refer to Figure 1 As shown, a natural gas chemical chain combustion system is shown in the figure, which mainly includes an air reactor 1 [oxidation reaction of oxygen carrier], a fuel reactor 2 [combustion reaction of natural gas], an AR cyclone separator 3 [gas / solid separation of oxygen carrier and high-temperature flue gas of the air reactor], a FR cyclone separator 4 [gas / solid separation of oxygen carrier and high-temperature flue gas of the fuel reactor], a splitter return device 5, a return device 6, and an H-type valve [oxygen carrier circulation control] composed of a circulation reaction device. When the entire system is running, the oxygen carrier continuously circulates between the air reactor 1 and the fuel reactor 2 and fully contacts and reacts with the natural gas, and the specific reactions that occur are:

[0043] 3MeO+CH 4 →CO 2 +2H 2 O+3Me

[0044] 2Me+O 2 →2MeO

[0045] Thus, efficient combustion of natural gas is achieved. The oxygen carrier is a metal oxide (including Ni, Fe, Cu, Co, Mn, etc. and composite metal oxides). By treating high-temperature flue gas, CO 2 Efficient separation.

[0046] The combustion method adopted by the chemical loop system is:

[0047] The fuel reactor 2 adopts a circulating fluidized bed form, which can achieve full contact between natural gas and oxygen carrier, and improve heat and mass transfer efficiency and reaction rate.

[0048] The FR cyclone separator 4 is used to receive the fuel reactor flue gas 12 and reduced oxygen carriers from the fuel reactor 2, and through its own efficient gas-solid separation characteristics, the fuel reactor flue gas 12 enters the FR flue gas treatment system 15 through the central tube, and the reduced oxygen carrier enters the return device 6 through the downcomer.

[0049] The return device 6 is used to receive the reduced oxygen carrier captured by the FR cyclone separator 4 and transport the reduced oxygen carrier back to the fuel reactor 2 .

[0050] The reduced oxygen carrier in the fuel reactor 2 is transported to the air reactor 1 through the H-type valve, and the circulating flow of the oxygen carrier is effectively controlled by controlling the recirculating flue gas flow of the H-type valve.

[0051] The air reactor 1 is used to receive the reduced oxygen carrier from the H-type valve and fully mix it with the fresh oxygen carrier and the air to perform a full oxidation reaction.

[0052] The AR cyclone separator 3 is used to receive the oxidized oxygen carrier and the air reactor flue gas 11 in the air reactor 1, and through its own high-efficiency gas-solid separation characteristics, the air reactor flue gas 11 enters the AR flue gas treatment system 14 through the central tube, and the oxidized oxygen carrier enters the diversion return device 5 through the downcomer.

[0053] The splitter return device 5 is used to receive the oxidized oxygen carrier captured by the AR cyclone separator 3, and transport a part of the oxidized oxygen carrier back to the air reactor 1, and transport the other part of the oxidized oxygen carrier to the fuel reactor to fully contact and react with the natural gas.

[0054] The above-mentioned device and combustion method can realize the efficient and economical operation of the natural gas chemical chain combustion system and reduce CO 2 Capture energy consumption. The device and combustion method can be used to transform existing gas boilers.

[0055] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A natural gas chemical chain combustion system, characterized in that: The natural gas chemical chain combustion system comprises: an air reactor (1), a fuel reactor (2), an AR cyclone separator (3), a FR cyclone separator (4), a split flow return device (5) and a return device (6); The top of the air reactor (1) is connected to the AR cyclone separator (3) via a pipeline. The air reactor (1) is configured to: complete an oxidation reaction based on the received oxygen carrier and air, and the generated oxidized oxygen carrier is transported to the AR cyclone separator (3) driven by the flue gas; The AR cyclone separator (3) is provided with a downcomer at the bottom end thereof, which is connected to a flow divider and return device (5); the flow divider and return device (5) is connected to the fuel reactor (2); the AR cyclone separator (3) is configured to complete gas-solid separation of the received material, and to input the oxidized oxygen carrier into the flow divider and return device (5); and the flow divider and return device (5) inputs the oxidized oxygen carrier into the fuel reactor (2); The fuel reactor (2) is provided with a pipeline on the top thereof connected to the FR cyclone separator (4). The fuel reactor (2) performs a redox reaction based on the received oxidized oxygen carrier and natural gas, and the generated fuel reactor flue gas containing water vapor and CO2 and the reduced oxygen carrier are input into the FR cyclone separator (4); The FR cyclone separator (4) has a downcomer at its bottom end connected to a return device (6), and the return device (6) has a pipeline at its bottom end connected to a fuel reactor (2). The FR cyclone separator (4) performs gas-solid separation on the received material, and transports the reduced oxygen carrier particles obtained by separation to the fuel reactor (2) via the return device (6); The bottom end of the fuel reactor (2) is provided with a pipeline connected to the air reactor (1) for transporting the reduced oxygen carrier back to the air reactor (1).

2. The natural gas chemical chaining combustion system according to claim 1, characterized in that: The AR cyclone separator (3) is externally connected to an AR flue gas treatment system (14) for treating the flue gas separated by the AR cyclone separator (3).

3. The natural gas chemical chaining combustion system according to claim 1, characterized in that: The split flow return device (5) is also provided with a pipeline connected to the air reactor (1) for returning part of the oxidized oxygen carrier to the air reactor (1).

4. The natural gas chemical chaining combustion system according to claim 1, characterized in that: A controllable valve (7) is provided on the connecting pipeline between the fuel reactor (2) and the air reactor (1).

5. The natural gas chemical chaining combustion system according to claim 4, characterized in that: The FR cyclone separator (4) is externally connected to a FR flue gas treatment system (15) for treating the flue gas separated by the FR cyclone separator (4).

6. The natural gas chemical chaining combustion system according to claim 5, characterized in that: A flue gas recirculation system (13) is provided downstream of the FR flue gas treatment system (15), and is connected to the diverter return device (5), the return device (6), and the controllable valve (7) respectively through the flue gas recirculation system (13).

7. The natural gas chemical chaining combustion system according to claim 6, characterized in that: The split-flow return device (5) and the return device (6) adopt fluidized bed equipment, and the fluidizing gas thereof is recycled flue gas.

8. The natural gas chemical chaining combustion system according to claim 1, characterized in that: The air reactor (1) adopts a circulating fluidized bed device. The fluidized material and reaction gas inside the air reactor (1) are air, and the corresponding air is provided by an external air supply system (9).

9. The natural gas chemical chaining combustion system according to claim 1, characterized in that: The fuel reactor (2) adopts a circulating fluidized bed device, and the fluidized material and reaction gas inside the fuel reactor (2) are natural gas and CO2+H2O generated by the reaction.

10. The natural gas chemical chaining combustion system according to claim 1, characterized in that: The oxygen carrier is a metal oxide, including Ni, Fe, Cu, Co, Mn and composite metal oxides thereof.

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