A method for filling ceramic balls in an axial-radial synthesis tower and a synthesis process

Abstract

This invention provides a method and process for filling ceramic balls into an axial-radial synthesis tower. The axial-radial synthesis tower includes a fixed-bed reactor with a central cavity, a central cylinder located within the central cavity of the fixed-bed reactor, an outer collector located on the side wall of the fixed-bed reactor, and a heat exchange tube sheet located within the central cavity of the fixed-bed reactor. The method includes: filling a plurality of ceramic balls into the bottom of the cavity formed by the fixed-bed reactor and the central cylinder. The upper surface of the filled ceramic ball pile has an inclined or curved surface with a gradually decreasing height from the inner wall of the fixed-bed reactor towards the center. The highest point of the upper surface is located below the lower edge of the opening of the outer collector on the inner wall of the fixed-bed reactor; the lowest point of the upper surface is flush with or covers the bottom of the heat exchange tube sheet. This invention provides a method for filling the insulation layer near the tower wall at the bottom of the fixed-bed reactor with ceramic balls, with the ceramic balls having a slope from the tower wall to the central cylinder, thus solving the problem of overheating of the insulation layer near the tower wall during production, which threatens the safe operation of the equipment.

Description

Technical Field

[0001] This invention belongs to the technical field of coal chemical equipment, and specifically relates to a method for filling ceramic balls in an axial-radial synthesis tower and a synthesis process. Background Technology

[0002] Current methanol synthesis typically employs the low-pressure isothermal methanol synthesis technology from Davy in the UK, which uses a fixed-bed pre-reactor and a steam-rising main reactor. The gas in the main reactor flows radially, resulting in a relatively small pressure drop.

[0003] The main reactor of the axial-radial synthesis tower contains key components such as a central cylinder, heat exchange tubes, and an external gas collector. Process gas enters the central cylinder from the bottom of the tower and flows radially through openings around the cylinder, passing through the catalyst bed surrounding the central cylinder to initiate the methanol synthesis reaction. The heat of reaction is carried away by steam in the heat exchange tubes within the catalyst bed. The generated methanol gas and unreacted process gas penetrate the catalyst bed and enter the downstream separation system via the gas collector. After cooling, gas-liquid separation occurs; liquid methanol is sent to the distillation section, while the gas is pressurized by a recirculating gas compressor and then recycled back into the reaction system. However, existing technologies using conventional catalyst loading methods are prone to overheating issues in the catalyst bed. Summary of the Invention

[0004] The purpose of this invention is to address the aforementioned problems in the prior art by providing a method for loading ceramic balls into an axial-radial synthesis tower and a synthesis process, thereby mitigating the risk of overheating of the catalyst bed near the tower wall at the bottom of the synthesis reactor and ensuring the long-term safe and stable operation of the equipment.

[0005] To achieve the above objectives, the present invention provides a method for filling ceramic balls in an axial-radial synthesis tower. The axial-radial synthesis tower includes a fixed-bed reactor with a central cavity, a central cylinder disposed within the central cavity of the fixed-bed reactor, an outer collector disposed on the side wall of the fixed-bed reactor, and a heat exchange tube sheet disposed within the central cavity of the fixed-bed reactor. The method includes: filling a plurality of ceramic balls at the bottom of the cavity formed by the fixed-bed reactor and the central cylinder; the upper surface of the filled ceramic ball pile has an inclined surface or curved surface whose height gradually decreases from the inner wall of the fixed-bed reactor towards the center; the highest point of the upper surface is located below the lower edge of the opening of the outer collector on the inner wall of the fixed-bed reactor; the lowest point of the upper surface is flush with or covers the bottom of the heat exchange tube sheet.

[0006] Preferably, the projection of the inclined surface or curved surface onto the bottom of the axial-radial synthesis tower is annular.

[0007] Preferably, the upper surface of the ceramic ball stack further includes a plane, which is located on the side closer to the central cylinder, and the inclined or curved surface is located on the side closer to the inner wall of the fixed bed reactor; the projection of the plane onto the bottom of the axial-radial synthesis tower is also annular.

[0008] Preferably, the upper surface of the ceramic ball stack has an inclined surface whose height gradually decreases from the inner wall of the fixed bed reactor towards the center, and the slope of the inclined surface is 0.4% to 0.7%.

[0009] Preferably, the bulk density of the ceramic balls is 1.3-1.4 kg / L.

[0010] Preferably, the vertical distance from the lower edge of the opening of the outer collector to the highest point of the upper surface of the ceramic ball pile is 0-5cm.

[0011] Preferably, the bulk density of the ceramic spheres is 1.3-1.4 kg / L.

[0012] The present invention also provides a methanol synthesis process for an axial-radial synthesis tower, comprising loading a ceramic ball stack according to the above method and loading a catalyst bed above the ceramic ball stack.

[0013] Preferably, the catalyst is a copper-based catalyst.

[0014] Compared with the prior art, the beneficial effects of the present invention are:

[0015] 1. This invention provides a method of filling the bottom of a fixed-bed reactor near the tower wall with ceramic balls. These ceramic balls form a gradually decreasing slope from the tower wall towards the central cylinder, solving the problem of excessive temperature in the catalyst bed (i.e., the insulation layer) near the tower wall during production, which affects the equipment's lifespan. Simultaneously, this invention arranges the ceramic balls, located below the opening of the outer collector, into a gradually decreasing slope or curved surface structure. This slope is very gentle and does not occupy catalyst space, thus avoiding the impact on methanol production caused by insufficient catalyst loading due to excessive ceramic balls at the bottom of the tower.

[0016] 2. This invention solves the risk of overheating of the bottom insulation layer during the operation of the Davy synthesis reactor, while ensuring the amount of catalyst loaded, thus meeting the requirements for long-term, high-load methanol production.

[0017] 3. This invention employs a method where the lowest point of the upper surface of the ceramic ball stack near the central cylinder of the fixed-bed reactor is flush with or covers the bottom of the heat exchange tube sheet. The filling height of the ceramic ball stack near the tower wall of the fixed-bed reactor is 0-5 cm from the lower edge of the outer collector opening to the top of the inclined surface of the ceramic ball. The height of the ceramic balls gradually decreases from the tower wall towards the central cylinder, forming a slope of 0.4-0.7%. The catalyst is then loaded onto the top of the ceramic balls. This method can eliminate the risk of high temperature. This is because in existing filling schemes, a non-circulating gas area is formed at the bottom of the catalyst bed near the outer collector. During operation, the non-circulating gas forms an adiabatic zone, causing overheating and posing a safety hazard. At the same time, this part of the catalyst contributes almost nothing to the entire reaction. To eliminate this potential hazard without affecting reaction efficiency due to reduced catalyst loading, 6mm ceramic balls were used to fill the dead zone between the inner and outer collectors of the catalyst bed. A slope of 0.4% to 0.7% was formed at the bottom of the catalyst bed along the inner distributor to the outer collector, reducing the dead zone and lowering the temperature of the adiabatic zone from 325℃ to 280℃. Attached Figure Description

[0018] Figure 1 This is a schematic diagram of a method for loading ceramic balls into an axial-radial synthesis tower, as provided in this invention. Figure 1 ;

[0019] Figure 2 This is a schematic diagram of a method for loading ceramic balls into an axial-radial synthesis tower, as provided in this invention. Figure 2 .

[0020] In the diagram: 1. Fixed-bed reactor, 2. Ceramic ball stack, 3. Central cylinder, 4. External collector, 5. Heat exchanger tube sheet. Detailed Implementation

[0021] To make the technical means, creative features, objectives and effects of the present invention easier to understand, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings.

[0022] In the description of this invention, it should be understood that the terms indicating orientation used in the description of the main body, such as "height," "length," "width," and "front surface," are descriptions based on the premise that the main body is placed vertically, that is, perpendicular to the ground. They are only for the convenience of describing this invention and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0023] Example 1

[0024] Six-mm ceramic balls are packed at the bottom of the fixed-bed reactor 1. The packed ceramic balls 2 are piled up near the inner wall of the fixed-bed reactor 1 to form a slope with a gradually decreasing height of 0.4% to 0.7% from the inner wall of the fixed-bed reactor 1 towards the center. The top of the slope is located below the lower edge of the opening of the outer collector 4 on the inner wall of the fixed-bed reactor 1. The vertical distance from the lower edge of the opening of the outer collector 4 to the top of the slope of the ceramic ball pile 2 is 0-5cm. The lowest point of the upper surface of the packed ceramic ball pile 2 is flush with or covers the bottom of the heat exchange tube sheet 5. The catalyst is packed in the cavity formed by the fixed-bed reactor 1 and the central cylinder 3 above the ceramic ball pile 2. The highest temperature of the catalyst bed near the tower wall, i.e. the temperature of the insulation layer, is obtained by a temperature detector installed on the inner wall of the catalyst bed of the fixed-bed reactor 1.

[0025] Comparative Example 1

[0026] like Figure 1 As shown, 6mm ceramic balls are filled into the cavity formed by multiple horizontally arranged heat exchange tube sheets 5 and the bottom of the fixed bed reactor 1. The upper surface of the ceramic ball stack 2 is flush with the lower surface of the heat exchange tube sheets 5. The highest temperature of the catalyst bed (i.e., the insulation layer) near the tower wall is obtained by a temperature detector set on the inner wall of the catalyst bed of the fixed bed reactor 1. The catalyst is filled into the cavity formed by the fixed bed reactor and the central cylinder 3 above the ceramic ball stack 2.

[0027] Comparative Example 2

[0028] 6mm ceramic balls are packed into the cavity formed by multiple horizontally arranged heat exchange tube sheets 5 and the bottom of the fixed-bed reactor 1. The packing height of the ceramic ball pile 2 near the wall of the fixed-bed reactor 1 is 0-5cm from the lower edge of the opening of the outer collector 4 on the inner wall of the fixed-bed reactor 1 to the top of the inclined surface of the ceramic ball pile 2. The packed ceramic balls 2 are stacked in a slope that gradually decreases from the inner wall of the fixed-bed reactor 1 towards the center. This slope is formed by the ceramic balls growing from the inner wall of the fixed-bed reactor 1 towards the center. The slope gradually decreases from 0.1% to 0.3%. The lowest point of the upper surface of the filled ceramic ball pile 2 is flush with or covers the bottom of the heat exchange tube sheet 5. The catalyst is filled in the cavity formed by the fixed bed reactor 1 and the central cylinder 3 above the ceramic ball pile 2. The highest temperature of the catalyst bed (i.e., the insulation layer) near the tower wall is obtained by a temperature detector set on the inner wall of the catalyst bed of the fixed bed reactor 1. The catalyst is filled in the cavity formed by the fixed bed reactor 1 and the central cylinder 3 above the ceramic balls.

[0029] Comparative Example 3

[0030] 6mm ceramic balls are packed into the cavity formed by multiple horizontally arranged heat exchange tube sheets 5 and the bottom of the fixed bed reactor 1. The packing height of the ceramic ball pile 2 near the tower wall of the fixed bed reactor 1 is 0-5cm from the lower edge of the opening of the outer collector 4 on the inner wall of the fixed bed reactor 1 to the top of the inclined surface of the ceramic ball pile 2. The ceramic ball pile 2 filled in the gap between the bottom of the outer collector 4 and the outer wall of the central cylinder 3 is piled up to form a gradually decreasing slope. This slope is formed by the ceramic ball pile 2 from the bottom of the outer collector 4 towards the top of the inclined surface of the outer collector 4. The central cylinder 3 forms a slope with a gradually decreasing gradient of 0.8% to 0.1%. The lowest point of the upper surface of the filled ceramic ball pile 2 is flush with or covers the bottom of the heat exchange tube sheet 5. The catalyst is filled in the cavity formed by the fixed bed reactor 1 and the central cylinder 3 above the ceramic ball pile 2. The highest temperature of the catalyst bed (i.e., the insulation layer) near the tower wall is obtained by a temperature detector set on the inner wall of the catalyst bed of the fixed bed reactor 1. The catalyst is filled in the cavity formed by the fixed bed reactor and the central cylinder 3 above the ceramic balls.

[0031] Comparative Example 4

[0032] 6mm ceramic balls and catalyst are mixed in a 1:1 ratio. This 1:1 mixture is then filled into the cavity formed by multiple horizontally arranged heat exchange tube sheets 5 and the bottom of the fixed-bed reactor 1. The filling height of the ceramic ball pile 2 near the wall of the fixed-bed reactor 1 is 0-5cm from the lower edge of the opening of the outer collector 4 on the inner wall of the fixed-bed reactor 1 to the top of the inclined surface of the ceramic ball pile 2. The pile is located between the bottom of the outer collector 4 and the outer wall of the central cylinder 3. The ceramic balls and catalyst filled in the gaps are stacked to form a slope with a gradually decreasing height. This slope is formed from the bottom of the outer collector 4 to the central cylinder 3 with a gradually decreasing slope of 0.4% to 0.7%. Then, the 6mm ceramic ball stack 2 and the catalyst are mixed in a 1:1 ratio and filled into the cavity formed between the fixed bed reactor and the central cylinder 3 on the upper part of the ceramic ball stack 2. The highest temperature of the catalyst bed near the tower wall (i.e., the insulation layer) is obtained by a temperature detector set on the inner wall of the catalyst bed of the fixed bed reactor 1.

[0033] After the catalyst and ceramic ball pile 2 were loaded using the catalyst loading methods given in Example 1 and Comparative Examples 1-4, the temperature values ​​obtained near the external collection point are shown in Table 1 below.

[0034] Table 1 shows the temperature values ​​detected by different catalyst loading methods.

[0035]

[0036] Table 1 shows that the temperature values ​​detected under different catalyst loading methods indicate that the loading method of Example 1 can control the temperature at 280℃. Although Comparative Examples 3 and 4 can also reduce the temperature to some extent, the cooling effect in Comparative Example 2 is not obvious, and the amount of catalyst loaded in Comparative Example 3 is small, which will affect the methanol production. However, the loading method of Example 1 can reduce the temperature and reduce the dead zone without affecting the methanol production.

[0037] In this embodiment, the ceramic balls near the center of the fixed-bed reactor are filled with ceramic balls at a height equal to the height of the heat exchange tube sheet. The ceramic balls near the tower wall of the fixed-bed reactor are filled with ceramic balls at a height of 0-5 cm, with the vertical distance from the lower edge of the outer collector opening to the top of the inclined surface of the ceramic balls being 0.5 cm. The ceramic balls gradually decrease in height from the tower wall to the center of the reactor, forming a slope of 0.4-0.7%. The catalyst is then filled on top of the ceramic balls. This filling method can eliminate the high-temperature hazard. This is because in the existing filling scheme, a gas-non-circulating area is formed at the bottom of the catalyst bed near the outer collector. During operation, the lack of gas circulation creates an adiabatic zone, causing overheating and posing a safety hazard. At the same time, this part of the catalyst contributes almost nothing to the entire reaction. To eliminate this potential hazard without affecting reaction efficiency due to reduced catalyst loading, 6mm ceramic balls were used to fill the dead zone between the inner and outer collectors of the catalyst bed. A slope of 0.4% to 0.7% was formed at the bottom of the catalyst bed along the inner distributor to the outer collector, reducing the dead zone and lowering the insulation temperature from 325℃ to 280℃.

[0038] In practical applications, we have found that the curved surface on the upper surface of the ceramic ball stack 2, which gradually decreases in height from the inner wall of the fixed bed reactor 1 towards the center, and the design as an inclined surface, both improve the problem of overheating in the catalyst bed, i.e. the insulation layer, near the tower wall. Since the inclined surface is more convenient to operate in actual production and also facilitates the filling of catalyst, the upper surface of the ceramic ball stack 2 can still maintain the designed slope after the catalyst is filled. Therefore, the inclined surface method is more preferred.

[0039] Similarly, for the other upper surfaces of the ceramic ball pile 2 besides the inclined surface, choosing a flat surface is not only more conducive to maintaining the slope of the ceramic ball pile 2 after the catalyst is filled, but also makes the filling of the ceramic ball pile 2 and the catalyst more convenient.

[0040] The above-disclosed embodiments are merely preferred embodiments of the present invention. However, the embodiments of the present invention are not limited thereto, and any variations that can be conceived by those skilled in the art should fall within the protection scope of the present invention.

Claims

1. A method for filling ceramic balls into an axial-radial synthesis tower, the axial-radial synthesis tower comprising a fixed-bed reactor (1) having a central cavity, a central cylinder (3) disposed within the central cavity of the fixed-bed reactor, an outer collector (4) disposed on the side wall of the fixed-bed reactor, and a heat exchange tube sheet (5) disposed within the central cavity of the fixed-bed reactor (1), characterized in that, The method includes: filling multiple ceramic balls into the bottom of the cavity formed by the fixed bed reactor (1) and the central cylinder (3), the upper surface of the filled ceramic ball pile (2) has an inclined or curved surface whose height gradually decreases from the inner wall of the fixed bed reactor (1) towards the center, the highest point of the upper surface is located below the lower edge of the opening of the outer collector (4) on the inner wall of the fixed bed reactor (1); the lowest point of the upper surface is flush with or covers the bottom of the heat exchange tube sheet (5).

2. The method for filling ceramic balls in an axial-radial synthesis tower as described in claim 1, characterized in that, The projection of the inclined or curved surface onto the bottom of the axial-radial synthesis tower is annular.

3. The method for filling ceramic balls in an axial-radial synthesis tower as described in claim 1, characterized in that, The upper surface of the ceramic ball stack (2) also includes a plane, which is located on the side close to the central cylinder (3), and the inclined or curved surface is located on the side close to the inner wall of the fixed bed reactor (1); the projection of the plane on the bottom of the axial-radial synthesis tower is also annular.

4. The method for filling ceramic balls in an axial-radial synthesis tower as described in claim 3, characterized in that, The upper surface of the ceramic ball stack (2) has an inclined surface whose height gradually decreases from the inner wall of the fixed bed reactor (1) towards the center, and the slope of the inclined surface is 0.4% to 0.7%.

5. The method for filling ceramic balls in an axial-radial synthesis tower as described in claim 1, characterized in that, The vertical distance from the lower edge of the opening of the external collector (4) to the highest point of the upper surface of the ceramic ball pile (2) is 0-5cm.

6. The method for filling ceramic balls in an axial-radial synthesis tower as described in claim 1, characterized in that, The bulk density of the ceramic ball stack (2) is 1.3-1.4 kg / L.

7. A methanol synthesis process using an axial-radial synthesis tower, characterized in that, This includes filling a ceramic ball stack as described in claim 1 and filling a catalyst bed on top of the ceramic ball stack.

8. The axial-radial synthesis tower methanol synthesis process as described in claim 7, characterized in that, The catalyst is a copper-based catalyst.

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