A cold hydrogenation vaporizer deslagging system

Abstract

The utility model discloses a kind of cold hydrogenation vaporizers, involve the technical field of discharging slag in cold hydrogenation section in polysilicon production, including vaporizer, gas-liquid separation tank and washing tower, the installation position of gas-liquid separation tank is lower than vaporizer, vaporizer's feed inlet I connects mixed gas inlet pipe, the material outlet I of vaporizer bottom is connected with the feed inlet II of gas-liquid separation tank by pipeline I, the outlet of vaporizer upper portion is communicated with gas-liquid separation tank by balance pipe, the liquid phase outlet of gas-liquid separation tank is connected with the feed inlet III of washing tower by pipeline II, valve I and valve II are respectively equipped on pipeline I and pipeline II, liquid level transmitter is installed on gas-liquid separation tank, liquid level transmitter is connected with valve II control, solve the problem that there is slag material flow in cold hydrogenation section to scour discharging slag pipeline.

Description

Technical Field

[0001] This utility model relates to the field of slag removal technology in the cold hydrogen chemical section of polysilicon production, specifically to a slag removal system for a cold hydrogen vaporizer. Background Technology

[0002] In the cold hydrogen chemical production process, the mixed raw material of silicon tetrachloride and hydrogen is preheated through multiple stages before entering the vaporizer, which is a vessel-type heat exchanger. This vaporizer uses U-shaped tubes to pass steam for heating, while the material flows in the shell side. To ensure heat exchange efficiency and fully utilize the equipment's performance, the production process controls the liquid level to ensure the top of the heat exchange tubes are completely submerged. Simultaneously, considering that the raw material enters the vaporizer in a gas-liquid two-phase state, to prevent gas-liquid erosion of the heat exchange tubes, the mixed raw material is introduced to the bottom of the vaporizer, and a downward-opening gas distributor is installed in the bottom pipe to achieve uniform gas distribution and reduce erosion.

[0003] However, impurities such as metallic chlorides in the raw material silicon tetrachloride cannot be discharged from the top of the vaporizer with the saturated process gas, causing these impurities to accumulate continuously at the bottom of the vaporizer. Statistics show that Yongxiang Co., Ltd.'s subsidiaries have experienced eight cases of heat exchange tube bundle corrosion and breakage due to insufficient slag discharge from the bottom of the vaporizer. The currently used intermittent slag discharge method, which involves opening the bottom slag discharge valve for 80-100 seconds every 600 seconds and conveying the discharged slag to the downstream scrubbing tower, avoids material waste. However, the 0.5-0.8 MPaG pressure difference between the vaporizer (3.0-3.2 MPaG) and the scrubbing tower (2.4-2.5 MPaG) causes strong erosion of the conveying pipeline by the gas-liquid two-phase slag. Inspection data shows that the pipeline wall thickness has worn down from an initial approximately 5.6 mm to 1 mm, with leaks even appearing in some areas.

[0004] Given that both chlorosilanes and hydrogen are highly hazardous materials, leaks would pose a serious threat to personnel safety and the ecological environment, and could also trigger an emergency system shutdown. Therefore, it is urgent to optimize and improve the existing slag discharge process. Summary of the Invention

[0005] The purpose of this invention is to solve the problem of slag material flow eroding the slag discharge pipeline in the cold hydrogen chemical section, and to propose a slag discharge system for a cold hydrogen vaporizer.

[0006] This invention is achieved through the following technical solution:

[0007] A slag discharge system for a cold hydrogenation vaporizer includes a vaporizer, a gas-liquid separator, and a scrubbing tower. The gas-liquid separator is installed below the vaporizer. The vaporizer's inlet I is connected to a mixed gas inlet pipe. The vaporizer's bottom outlet I is connected to the gas-liquid separator's inlet II via pipe I. The vaporizer's upper outlet is connected to the gas-liquid separator via a balance pipe. The gas-liquid separator's liquid phase outlet is connected to the scrubbing tower's inlet III via pipe II. Pipes I and II are respectively equipped with valve I and valve II. A level transmitter is installed on the gas-liquid separator, and the level transmitter is connected to valve II for control.

[0008] Furthermore, the outlet at the top of the vaporizer is connected to the material inlet of the superheater via pipe III.

[0009] Furthermore, the material outlet of the superheater is connected to the reactor via pipe IV.

[0010] Furthermore, the vaporizer is a kettle-type heat exchanger, and U-shaped heat exchange tube bundles are distributed inside the vaporizer.

[0011] Furthermore, the gas-liquid separator is equipped with a wire mesh for intercepting liquid phase flow.

[0012] Furthermore, the wire mesh is a mesh structure made of stainless steel 304 / 316 material.

[0013] Furthermore, a high-temperature, high-pressure gas discharge pipeline is connected to the top of the washing tower.

[0014] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0015] I. In this utility model, a gas-liquid separator is added to the slag discharge pipeline from the vaporizer to the scrubbing tower in the slag discharge system of the cold hydrogen vaporizer. A balance pipe is installed between the top of the gas-liquid separator and the top of the vaporizer to ensure that the pressure in the gas-liquid separator and the vaporizer are basically the same. This allows the liquid phase in the vaporizer, which is located at a higher level, to enter the gas-liquid separator through pipe I under the action of gravity. Under this condition, the material of the gas and liquid phases has a low flow rate and does not cause much scouring of the pipeline. After the material enters the gas-liquid separator for gas-liquid separation, the liquid phase silicon tetrachloride can be stably sent to the scrubbing tower by controlling the liquid level of the gas-liquid separator. In this way, the scouring problem of the slag discharge pipeline under the existing process flow is solved.

[0016] II. In this utility model, the outlet at the top of the vaporizer is connected to the material inlet of the superheater through pipe III. After being processed by the vaporizer, a mixture of hydrogen and silicon tetrachloride is obtained. This mixture is then heated by the superheater through pipe III and can be sent to the reactor as raw material gas for recycling, thereby reducing the loss of raw material gas and heat.

[0017] Third, in this utility model, the vaporizer is a kettle-type heat exchanger, and the vaporizer has U-shaped heat exchange tube bundles distributed inside, which facilitates the installation and replacement of the tube bundles and is not easy to clog.

[0018] Fourth, in this utility model, a wire mesh for intercepting liquid phase flow is installed inside the gas-liquid separator. The wire mesh is a mesh structure made of stainless steel 304 / 316 material to ensure the separation effect. Attached Figure Description

[0019] Figure 1 This is a schematic diagram of the slag discharge system of the cold hydrogenation vaporizer.

[0020] Figure 2 This is a schematic diagram of another implementation of the slag discharge system for a cold hydrogenation vaporizer.

[0021] Figure 3 This is a schematic diagram of another implementation of the slag discharge system for a cold hydrogenation vaporizer.

[0022] Figure 4 This is a schematic diagram of the vaporizer.

[0023] Figure 5 This is a schematic diagram of the gas-liquid separator.

[0024] Among them, 1. Vaporizer; 2. Gas-liquid separator; 3. Scrubber; 4. Mixed gas inlet pipe; 5. Pipeline I; 6. Balance pipe; 7. Pipeline II; 8. Valve I; 9. Valve II; 10. Level transmitter; 11. Pipeline III; 12. Superheater; 13. Pipeline IV; 14. Reactor; 15. High temperature and high pressure gas discharge pipeline; 1.1. Feed inlet I; 1.2. Material outlet I; 1.3. Outlet; 1.4. U-shaped heat exchange tube bundle; 2.1. Feed inlet II; 2.2. Liquid phase outlet; 2.3. Wire mesh; 3.1. Feed inlet III; 12.1. Material inlet; 12.2. Material outlet. Detailed Implementation

[0025] The present invention will be further described in detail below with reference to embodiments, but the implementation of the present invention is not limited thereto.

[0026] Example 1

[0027] A slag discharge system for a cold hydrogenation vaporizer includes a vaporizer 1, a gas-liquid separator 2, and a scrubbing tower 3. (Reference) Figure 1The gas-liquid separator 2 is installed lower than the vaporizer 1. The inlet I1.1 of the vaporizer 1 is connected to the mixed gas inlet pipe 4. The material outlet I1.2 at the bottom of the vaporizer 1 is connected to the inlet II2.1 of the gas-liquid separator 2 through pipe I5. The outlet 1.3 at the top of the vaporizer 1 is connected to the gas-liquid separator 2 through the balance pipe 6. The liquid phase outlet 2.2 of the gas-liquid separator 2 is connected to the inlet III3.1 of the washing tower 3 through pipe II7. Valves I8 and II9 are respectively installed on pipe I5 and pipe II7. A liquid level transmitter 10 is installed on the gas-liquid separator 2, and the liquid level transmitter 10 is connected to valve II9 for control.

[0028] Preferably, the top of the washing tower 3 is connected to a high-temperature and high-pressure gas discharge pipeline 15.

[0029] Example 2

[0030] This embodiment is a further optimization of embodiment 1, the difference being that, as referenced... Figure 2 The outlet 1.3 at the top of the vaporizer 1 is connected to the material inlet 12.1 of the superheater 12 via pipe Ⅲ11.

[0031] Example 3

[0032] The difference between this embodiment and embodiments 1-2 is that, in reference to... Figure 3 The material outlet 12.2 of the superheater 12 is connected to the reactor 14 via pipe IV 13.

[0033] Example 4

[0034] The difference between this embodiment and embodiments 1-3 is that the vaporizer 1 is a kettle-type heat exchanger, as shown in the reference. Figure 4 The vaporizer 1 has U-shaped heat exchange tube bundles 1.4 distributed inside.

[0035] Example 5

[0036] Compared with Examples 1-4, the difference in this embodiment is that the gas-liquid separator 2 is equipped with a wire mesh 2.3 for intercepting the liquid phase flow. (Refer to...) Figure 5 Preferably, the wire mesh 2.3 is a mesh structure made of stainless steel 304 / 316 material.

[0037] Example 6

[0038] A cold hydrogenation vaporizer slag discharge system includes a vaporizer 1, a gas-liquid separator 2, and a scrubbing tower 3, as shown in the reference. Figure 3The gas-liquid separator 2 is installed lower than the vaporizer 1. The inlet I1.1 of the vaporizer 1 is connected to the mixed gas inlet pipe 4. The material outlet I1.2 at the bottom of the vaporizer 1 is connected to the inlet II2.1 of the gas-liquid separator 2 through pipe I5. The outlet 1.3 at the top of the vaporizer 1 is connected to the gas-liquid separator 2 through the balance pipe 6. The liquid phase outlet 2.2 of the gas-liquid separator 2 is connected to the inlet III3.1 of the scrubbing tower 3 through pipe II7. Valves I8 and II9 are respectively installed on pipe I5 and pipe II7. A level transmitter 10 is installed on the gas-liquid separator 2. The level transmitter 10 is connected to valve II9 for control. A high-temperature and high-pressure gas discharge pipeline 15 is connected to the top of the scrubbing tower 3.

[0039] In this embodiment, the outlet 1.3 at the top of the vaporizer 1 is connected to the material inlet 12.1 of the superheater 12 via pipe III 11.

[0040] In this embodiment, the material outlet 12.2 of the superheater 12 is connected to the reactor 14 via pipe IV 13.

[0041] In this embodiment, the vaporizer 1 is a kettle-type heat exchanger, as shown in the reference. Figure 4 The vaporizer 1 has U-shaped heat exchange tube bundles 1.4 distributed inside.

[0042] In this embodiment, the gas-liquid separator 2 is equipped with a wire mesh 2.3 for intercepting liquid phase flow, as shown in the reference. Figure 5 The wire mesh 2.3 is a mesh structure made of stainless steel 304 / 316 material.

[0043] In this embodiment, a gas-liquid separator 2 is added to the slag discharge pipeline between the vaporizer 1 and the scrubbing tower 3. A balance pipe 6 is installed between the top of the gas-liquid separator 2 and the top of the vaporizer 1, and the gas-liquid separator 2 is installed below the vaporizer 1. During daily control, the bottom of the vaporizer 1 is discharged intermittently, with the bottom slag discharge valve opened once every 600 seconds for 80-100 seconds, and the slag is first discharged into the gas-liquid separator 2. Since the gas-liquid separator 2 and the top of the vaporizer 1 are connected through the balance pipe 6, the pressure of the two is basically the same, and the material at the bottom of the vaporizer 1 is discharged into the gas-liquid separator 2 by gravity. Even though the material is a two-phase gas and liquid, the flow rate is low, and the scouring effect on the pipeline is small. After the material enters the gas-liquid separator 2 for gas-liquid separation, the liquid phase silicon tetrachloride is transported to the scrubbing tower 3 by controlling the liquid level of the gas-liquid separator 2. At this point, the pressure in gas-liquid separator 2 is 3.0~3.2 MPaG, the control pressure in scrubbing tower 3 is 2.4~2.5 MPaG, the temperature in vaporizer 1 (gas-liquid separator 2) is 140~150℃, and the temperature in scrubbing tower 3 is 140~160℃. Silicon tetrachloride vaporizes at a temperature of approximately 210℃ under the control pressure in scrubbing tower 3. Therefore, no vaporization occurs during the discharge of silicon tetrachloride from gas-liquid separator 2 to scrubbing tower 3. This means that the slag discharge pipeline from gas-liquid separator 2 to scrubbing tower 3 is entirely in liquid phase, preventing gas-liquid scouring of the pipeline. This system design effectively solves the scouring problem of slag discharge pipelines in existing processes.

[0044] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Any simple modifications or equivalent changes made to the above embodiments based on the technical essence of the present invention shall fall within the protection scope of the present invention.

Claims

1. A slag discharge system for a cold hydrogenation vaporizer, characterized in that: The system includes a vaporizer (1), a gas-liquid separator (2), and a scrubbing tower (3). The gas-liquid separator (2) is installed at a position lower than the vaporizer (1). The inlet I (1.1) of the vaporizer (1) is connected to the mixed gas inlet pipe (4). The material outlet I (1.2) at the bottom of the vaporizer (1) is connected to the inlet II (2.1) of the gas-liquid separator (2) through pipe I (5). The outlet (1.3) at the top of the vaporizer (1) is connected to the gas-liquid separator (2) through a balance pipe (6). The liquid phase outlet (2.2) of the gas-liquid separator (2) is connected to the inlet III (3.1) of the scrubbing tower (3) through pipe II (7). Valves I (8) and II (9) are respectively installed on pipe I (5) and pipe II (7). A level transmitter (10) is installed on the gas-liquid separator (2). The level transmitter (10) is connected to valve II (9) for control.

2. The slag discharge system for a cold hydrogenation vaporizer according to claim 1, characterized in that: The outlet (1.3) at the top of the vaporizer (1) is connected to the material inlet (12.1) of the superheater (12) via pipe III (11).

3. The slag discharge system for a cold hydrogenation vaporizer according to claim 2, characterized in that: The material outlet (12.2) of the superheater (12) is connected to the reactor (14) via pipe IV (13).

4. The slag discharge system for a cold hydrogenation vaporizer according to claim 1, characterized in that: The vaporizer (1) is a kettle-type heat exchanger, and U-shaped heat exchange tube bundles (1.4) are distributed inside the vaporizer (1).

5. The slag discharge system for a cold hydrogenation vaporizer according to claim 1, characterized in that: The gas-liquid separator (2) is equipped with a wire mesh (2.3) for intercepting liquid phase flow.

6. The slag discharge system for a cold hydrogenation vaporizer according to claim 5, characterized in that: The wire mesh (2.3) is a mesh structure made of stainless steel 304 / 316 material.

7. The slag discharge system for a cold hydrogenation vaporizer according to claim 6, characterized in that: The top of the scrubbing tower (3) is connected to a high-temperature and high-pressure gas discharge pipeline (15).

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