A SF6 thermal degradation and CO2 recovery device

Abstract

The present invention discloses an SF6 thermal degradation and CO2 recovery device, comprising a bubbling bed reactor with a first feed port and a discharge port at the top and a second feed port at the bottom; the first feed port is connected to a limestone storage tank; the second feed port is connected to an SF6 feed pipe; the discharge port is connected to the inlet of a fast bed reactor; the outlet of the fast bed reactor is connected to a cyclone separator; the bubbling bed reactor is in the shape of a tank; the fast bed reactor is in the shape of an elongated tube; the caliber of the discharge port shrinks from the bubbling bed reactor to the fast bed reactor. The device utilizes the bubbling bed reactor and its feed direction to ensure full contact and efficient reaction of the raw materials, meets the SF6 degradation demand with less limestone in a shorter time, can reduce costs, energy consumption and improve degradation efficiency; the device also adjusts the flow direction and flow rate of the material in the bubbling bed reactor in combination with the fast bed reactor so that the products can smoothly enter the cyclone separator for separation, facilitating subsequent recovery and processing of various products.

Description

Technical Field

[0001] The present invention relates to the field of SF6 thermal degradation, and in particular to a SF6 thermal degradation and CO2 recovery device. Background Art

[0002] SF6 (sulfur hexafluoride) is widely used as an insulating material in various high-voltage electrical equipment due to its excellent electrical properties and arc-extinguishing performance. However, SF6's Global Warming Potential (GWP) is 23,900 times that of CO2, and its atmospheric degradation rate is very slow, taking approximately 3,200 years. Therefore, the Kyoto Protocol, signed in 1997, listed SF6 as one of the six greenhouse gases with restricted emissions.

[0003] At present, the pyrolysis method is mostly used to degrade SF6 after the retirement of electrical equipment, that is, SF6 is introduced into the industrial waste gas treatment furnace. 6(g) , causing it to react chemically with limestone (mainly CaCO3) at a high temperature above 1100°C, thereby converting it into naturally occurring substances such as gypsum (mainly CaSO4) and fluorite (mainly CaF2).

[0004] However, the above-mentioned thermal degradation operation has disadvantages such as low reaction efficiency, large amount of limestone used, high energy consumption and economic cost, and large amount of CO2 emitted into the atmosphere. Summary of the Invention

[0005] The purpose of the present invention is to provide an SF6 thermal degradation and CO2 recovery device, which can reduce the amount of limestone and the energy consumption of thermal degradation by improving the reaction efficiency of raw materials. In addition to collecting solid products, it can also reasonably and effectively realize the enrichment and recovery of CO2.

[0006] To achieve the above-mentioned objectives, the present invention provides an SF6 thermal degradation and CO2 recovery device, comprising a bubbling bed reactor having a first feed port and a discharge port at the top and a second feed port at the bottom; the first feed port is connected to a limestone storage tank; the second feed port is connected to an SF6 feed pipe; the discharge port is connected to the inlet of a fast bed reactor; the outlet of the fast bed reactor is connected to a cyclone separator; the bubbling bed reactor is in the shape of a tank; the fast bed reactor is in the shape of a slender tube; the diameter of the discharge port shrinks from the bubbling bed reactor to the fast bed reactor.

[0007] Preferably, a feeding pipe is provided between the limestone storage tank and the bubbling bed reactor; the sum of the pressure in the limestone storage tank and the pressure in the feeding pipe is not less than the pressure in the bubbling bed reactor.

[0008] Preferably, a return valve is provided in the feeding pipe.

[0009] Preferably, the pressure in the bubbling bed reactor is 1 to 5 kPa greater than the pressure in the limestone storage tank.

[0010] Preferably, the limestone storage tank is an open tank with an open top.

[0011] Preferably, the cyclone separator comprises a gas outlet for allowing CO2 to flow out and a solid outlet open downward for allowing SF6 and CaSO4 to settle downward.

[0012] Preferably, a product storage tank is connected below the solid outlet.

[0013] Preferably, the product storage tank is a narrow-necked tank.

[0014] Preferably, a slender tubular guide pipe is connected between the solid outlet and the product storage tank.

[0015] Preferably, the inner diameter of the bubbling bed reactor is 3 to 5 times the inner diameter of the fast bed reactor.

[0016] Compared with the above background technology, the SF6 thermal degradation and CO2 recovery device provided by the present invention includes a bubbling bed reactor with a first feed port and a discharge port on the top and a second feed port on the bottom; the first feed port is connected to a limestone storage tank; the second feed port is connected to an SF6 feed pipe; the discharge port is connected to the inlet of a fast bed reactor; the outlet of the fast bed reactor is connected to a cyclone separator; the bubbling bed reactor is in the shape of a tank; the fast bed reactor is in the shape of a slender tube; the diameter of the discharge port shrinks from the bubbling bed reactor to the fast bed reactor.

[0017] In the above-mentioned SF6 thermal degradation and CO2 recovery device, the bubbling bed reactor is in the shape of a can, while the fast bed reactor is in the shape of a slender tube. The can-shaped structure of the bubbling bed reactor, combined with the feed direction, can provide a larger space for SF6 and limestone to fully mix, contact, and react. In contrast, the fast bed reactor, due to its slender tubular shape, has a larger difference in cavity diameter from the aforementioned bubbling bed reactor, causing the junction of the two, i.e., the discharge port of the bubbling bed reactor, to shrink sharply. This can increase the flow rate to 9 to 25 times the flow rate of the airflow in the bubbling bed reactor, thereby allowing the generated CaSO4, CaF2, and CO2 to form a high-speed airflow in the fast bed reactor. The aforementioned high-speed airflow not only ensures that the products can smoothly enter the downstream cyclone separator, but also allows a very small amount of unreacted raw materials to fully contact and react in the slender fast bed reactor.

[0018] As the products enter the cyclone separator, solid CaSO4, CaF2 and gaseous CO2 flow out from different outlets of the cyclone separator under the action of the cyclone separator, simplifying the subsequent recovery and treatment of CO2.

[0019] It can be seen that in the SF6 thermal degradation and CO2 recovery device, the raw materials are fully contacted and reacted efficiently in the bubbling bed reactor. Combined with the fast bed reactor, the reaction efficiency of the limestone can be guaranteed, and the SF6 degradation demand can be met with less limestone in a shorter time, thereby reducing costs and energy consumption and improving degradation efficiency; and the products form a fast airflow between the bubbling bed reactor and the fast bed reactor, so that they can smoothly enter the cyclone separator for separation, which is convenient for the subsequent recovery and processing of different types of products. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are merely embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the provided drawings without paying any creative work.

[0021] Figure 1 This is a structural schematic diagram of the SF6 thermal degradation and CO2 recovery device provided in an embodiment of the present invention.

[0022] Among them, 1-limestone storage tank, 2-feeding pipe, 3-return valve, 4-bubbling bed reactor, 5-fast bed reactor, 6-cyclone separator, 61-gas outlet, 7-guide pipe, 8-product storage tank. DETAILED DESCRIPTION

[0023] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0024] In order to enable those skilled in the art to better understand the solutions of the present invention, the present invention is further described in detail below with reference to the accompanying drawings and specific implementation methods.

[0025] Please refer to Figure 1 , Figure 1 This is a schematic diagram of the structure of the SF6 thermal degradation and CO2 recovery device provided by an embodiment of the present invention. Arrow a indicates the inflow direction of gaseous SF6, and arrow b indicates the outflow direction of gaseous CO2.

[0026] The present invention provides an SF6 thermal degradation and CO2 recovery device, comprising a limestone storage tank 1, a bubbling bed reactor 4, a fast bed reactor 5 and a cyclone separator 6; wherein, a first feed port and a discharge port are provided on the top of the bubbling bed reactor 4, the first feed port is connected to the limestone storage tank 1, and is used to supply the material in the limestone storage tank 1 to enter the bubbling bed reactor 4 from top to bottom, and the discharge port is connected to the feed port of the cyclone separator 6; a second feed port is provided at the bottom of the bubbling bed reactor 4, and the second feed port is connected to the SF6 feed pipe, and is used to supply the material in the SF6 feed pipe to enter the bubbling bed reactor 4 from bottom to top.

[0027] For the SF6 thermal degradation and CO2 recovery device, the limestone storage tank 1 and the SF6 feed pipe both serve as raw material supply devices. For example, the limestone storage tank 1 provides solid limestone or a substance whose main component is CaCO3 to the bubbling bed reactor 4, and the SF6 feed pipe provides gaseous SF6 to the bubbling bed reactor 4; the bubbling bed reactor 4 and the fast bed reactor 5 both serve as high-temperature reaction vessels, used for the substances provided by the aforementioned limestone storage tank 1 and the SF6 feed pipe respectively to undergo chemical reactions under a specific high-temperature environment; the cyclone separator 6 is used to realize the classification and separation of products after the aforementioned chemical reaction is completed.

[0028] The reaction mechanism of the above process is described below:

[0029]

[0030] CaO+2SF6—→2SO2+6CaF+O2

[0031] 2SO2+O2—→2SO3

[0032] CaO+SO3—→CaSO4

[0033] In the above chemical formula, "heat" generally refers to a temperature greater than 900° C. This means that the SF6 thermal degradation and CO2 recovery device provided by the present invention requires that the bubbling bed reactor 4 and the fast bed reactor 5 be placed in a high-temperature environment that meets the aforementioned temperature requirements in order to achieve thermal degradation of SF6.

[0034] When using this SF6 thermal degradation and CO2 recovery device to thermally degrade SF6, the solid limestone in the limestone storage tank 1 moves downward from the first feed port and falls into the bubbling bed reactor 4, while the gaseous SF6 in the SF6 feed pipe moves upward from the second feed port and is blown into the bottom of the bubbling bed reactor 4. During this process, the shape and size of the bubbling bed reactor 4 and the feed direction of the aforementioned raw materials all facilitate full contact and rapid reaction between the SF6 that has entered the bubbling bed reactor 4 and the limestone, allowing the vast majority of the raw materials, namely SF6 and limestone, to react to produce solid CaSO4, CaF2, and gaseous CO2.

[0035] Because the bubbling bed reactor 4 is in the shape of a tank and the fast bed reactor 5 is in the shape of an elongated tube, on the one hand, the raw materials SF6 and limestone can be fully mixed, contacted, and reacted with each other in the larger space of the bubbling bed reactor 4. On the other hand, there is a large difference in the inner diameter of the cavity between the bubbling bed reactor 4 and the fast bed reactor 5, that is, the inner diameter is sharply reduced at the junction of the two, which can increase the flow rate to 9 to 25 times the flow rate of the airflow in the bubbling bed reactor 4, thereby forming a high-speed airflow of the generated products CaSO4, CaF2, and CO2. The aforementioned high-speed airflow not only ensures that the products can smoothly enter the downstream cyclone separator 6, but also allows a small amount of unreacted raw materials to fully contact and react in the elongated fast bed reactor 5.

[0036] The shapes of the bubbling bed reactor 4 and the fast bed reactor 5 are relative, that is, the bubbling bed reactor 4 has a larger radial dimension and a smaller axial dimension than the fast bed reactor 5; and the fast bed reactor 5 has a smaller radial dimension and a larger axial dimension than the bubbling bed reactor 4. For example, the inner diameter of the bubbling bed reactor 4 can be set to 3 to 5 times the inner diameter of the fast bed reactor 5.

[0037] As the product enters the cyclone separator 6 from the fast bed reactor 5, solid CaSO4, CaF2 and gaseous CO2 flow out from different outlets of the cyclone separator 6 under the action of the cyclone separator 6, thereby simplifying the subsequent effective collection and treatment of CO2 by enriching CO2.

[0038] In summary, the SF6 thermal degradation and CO2 recovery device provided by the present invention utilizes the bubbling bed reactor 4 to reasonably and effectively ensure sufficient contact and efficient reaction of the raw materials. Combined with the fast bed reactor 5, it can improve the reaction efficiency of limestone, and meet the SF6 degradation requirements with less limestone in a shorter time, thereby reducing costs, reducing energy consumption and improving degradation efficiency; and the products form a fast airflow between the bubbling bed reactor 4 and the fast bed reactor 5, so that they can smoothly enter the cyclone separator 6 for separation, which is convenient for subsequent recovery and processing of different types of products.

[0039] The SF6 thermal degradation and CO2 recovery device provided by the present invention will be further described below in conjunction with the accompanying drawings and implementation examples.

[0040] In this SF6 thermal degradation and CO2 recovery device, after the raw materials undergo a chemical reaction in the bubbling bed reactor 4 to generate products, the products enter the fast bed reactor 5 from the discharge port and do not enter the limestone storage tank 1. Therefore, a structure is provided between the bubbling bed reactor 4 and the limestone storage tank 1 to prevent the reverse flow of materials, including but not limited to valves and other components. The aforementioned reverse flow specifically refers to the direction from the bubbling bed reactor 4 into the limestone storage tank 1.

[0041] In order to simplify and improve the operation of the SF6 thermal degradation and CO2 recovery device, in a specific embodiment provided by the present invention, a feeding pipe 2 is provided between the limestone storage tank 1 and the bubbling bed reactor 4.

[0042] The feed pipe 2 is arranged vertically or inclined relative to the horizontal direction. Its function is to maintain a specific pressure difference between the limestone storage tank 1 and the bubbling bed reactor 4. More specifically, the sum of the pressure in the limestone storage tank 1 and the pressure in the feed pipe 2 is not less than the pressure in the bubbling bed reactor 4. Typically, the sum of the pressure in the limestone storage tank 1 and the pressure in the feed pipe 2 is equal to the pressure in the bubbling bed reactor 4. In other words, the specific size and shape of the feed pipe 2 depends on the pressure difference between the bubbling bed reactor 4 and the limestone storage tank 1.

[0043] Because a specific pressure difference is maintained between the limestone storage tank 1 and the bubbling bed reactor 4 via the feed pipe 2, the product in the bubbling bed reactor 4 does not flow back from the first feed port to the limestone storage tank 1, but instead flows from the discharge port to the cyclone separator 6. Thus, by using the feed pipe 2 to ensure the flow of materials within the SF6 thermal degradation and CO2 recovery device, the operator can be relieved of the need to repeatedly adjust the on / off state between the limestone storage tank 1 and the bubbling bed reactor 4. In other words, the limestone storage tank 1 can continuously and uninterruptedly add raw materials to the bubbling bed reactor 4.

[0044] Of course, in order to better control the supply of raw materials from the limestone storage tank 1 to the bubbling bed reactor 4, a return valve 3 is provided in the feed pipe 2. The return valve 3 can not only assist the feed pipe 2 to ensure that the material does not flow back into the limestone storage tank 1, but also play a role in regulating the rate at which the limestone storage tank 1 supplies raw materials to the bubbling bed reactor 4.

[0045] The pressure differential between the bubbling bed reactor 4 and the limestone storage tank 1 described above can be set to 1-5 kPa, meaning that the pressure within the bubbling bed reactor 4 is 1-5 kPa greater than the pressure within the limestone storage tank 1. As can be seen from the above description, this pressure differential corresponds to the specific shape and dimensions of the feed pipe 2. In practice, a feed pipe 2 with a vertical height of at least 1 meter can typically maintain the aforementioned pressure differential.

[0046] In the SF6 thermal degradation and CO2 recovery device provided by the present invention, the limestone storage tank 1 can be a tank with an open top. In this case, the pressure inside the limestone storage tank 1 is always equal to atmospheric pressure, which facilitates maintaining the pressure difference between the bubbling bed reactor 4 and the limestone storage tank 1 and facilitates replenishing raw materials into the limestone storage tank 1.

[0047] In the SF6 thermal degradation and CO2 recovery device provided by the present invention, the cyclone separator 6 includes a gas outlet 61 for CO2 to flow out and a solid outlet for SF6 and CaSO4 to settle. The solid outlet is open downward to facilitate the rapid downward settling of solid SF6 and CaSO4.

[0048] Furthermore, the bottom of the solid outlet can be connected to a product storage tank 8 for centralized recovery of SF6 and CaSO4.

[0049] To prevent the SF6 and CaSO4 already in product tank 8 from being affected by the airflow and interfering with CO2 enrichment and recovery, product tank 8 is specifically a narrow-necked tank, meaning its opening is much smaller than the radial dimension of its bottom storage cavity. Furthermore, a slender, tubular guide tube 7 can be connected between the solids outlet and product tank 8. This guide tube 7 not only constrains the flow path of SF6 and CaSO4, but also balances the overall dimensions of the SF6 thermal degradation and CO2 recovery apparatus, particularly balancing the height difference between the bubbling bed reactor 4 and product tank 8 caused by the connection to the fast bed reactor 5.

[0050] The above is a detailed introduction to the SF6 thermal degradation and CO2 recovery device provided by the present invention. Specific examples are used herein to illustrate the principles and implementation methods of the present invention. The description of the above embodiments is only used to help understand the method of the present invention and its core idea. It should be pointed out that for ordinary technicians in this technical field, without departing from the principles of the present invention, the present invention can also be improved and modified in several ways, and these improvements and modifications also fall within the scope of protection of the claims of the present invention.

Claims

1. A SF6 thermal degradation and CO2 recovery device, characterized in that: The invention comprises a bubbling bed reactor (4) provided with a first feed port and a discharge port at the top and a second feed port at the bottom; the first feed port is connected to a limestone storage tank (1); the second feed port is connected to an SF6 feed pipe; the discharge port is connected to the inlet of a fast bed reactor (5); the outlet of the fast bed reactor (5) is connected to a cyclone separator (6); the bubbling bed reactor (4) is in the shape of a tank; the fast bed reactor (5) is in the shape of a slender tube; the diameter of the discharge port shrinks from the bubbling bed reactor (4) to the fast bed reactor (5).

2. The SF6 thermal degradation and CO2 recovery device according to claim 1 is characterized in that: A feeding pipe (2) is provided between the limestone storage tank (1) and the bubbling bed reactor (4); the sum of the pressure in the limestone storage tank (1) and the pressure in the feeding pipe (2) is not less than the pressure in the bubbling bed reactor (4).

3. The SF6 thermal degradation and CO2 recovery device according to claim 2 is characterized in that: A return valve (3) is provided in the feeding pipe (2).

4. The SF6 thermal degradation and CO2 recovery device according to claim 2 is characterized in that: The pressure in the bubbling bed reactor (4) is 1 to 5 kPa greater than the pressure in the limestone storage tank (1).

5. The SF6 thermal degradation and CO2 recovery device according to claim 1 is characterized in that: The limestone storage tank (1) is an open tank with an open top.

6. The SF6 thermal degradation and CO2 recovery device according to any one of claims 1 to 5, characterized in that: The cyclone separator (6) comprises a gas outlet (61) for allowing CO2 to flow out and a solid outlet open downward for allowing SF6 and CaSO4 to settle downward.

7. The SF6 thermal degradation and CO2 recovery device according to claim 6 is characterized in that: A product storage tank (8) is connected below the solid outlet.

8. The SF6 thermal degradation and CO2 recovery device according to claim 7 is characterized in that: The product storage tank (8) is a narrow-necked tank.

9. The SF6 thermal degradation and CO2 recovery device according to claim 7, characterized in that: A slender tubular guide pipe (7) is connected between the solid outlet and the product storage tank (8).

10. The SF6 thermal degradation and CO2 recovery device according to claim 1, characterized in that: The inner diameter of the bubbling bed reactor (4) is 3 to 5 times the inner diameter of the fast bed reactor (5).

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