A device for dissolving fine oxalic acid powder suitable for oxalic acid plant

Abstract

The utility model provides a kind of oxalic acid fine powder dissolving device suitable for oxalic acid device, it is related to the technical field of reaction kettle, compared with prior art, the application is by setting up fine powder bin with weigher, solve the problem of no measurement in traditional process, rely on experience to judge the problem, realize fine powder feeding amount real-time monitoring and accurate control, avoid material concentration imbalance and equipment scaling;At the same time, the flow control module on hot salt dewatering conveying pipeline, make up the defect of no measurement control of desalted water, can guarantee the stability of desalted water supply amount, prevent paste from being formed due to water shortage to cause agitator failure, finally improve the stability, continuity of oxalic acid production process, reduce operating cost.

Description

Technical Field

[0001] This utility model relates to the field of reaction vessel technology, and more specifically, to a device for dissolving fine oxalic acid powder suitable for oxalic acid plants. Background Technology

[0002] In the post-processing stage of the drying unit in the hydrolysis of dimethyl oxalate to oxalic acid, the recovery and dissolution of fine oxalic acid powder is a crucial step to ensure raw material utilization and production continuity. In traditional processes, the drying unit conveyor is directly connected to the fine oxalic acid powder dissolution tank. This design lacks any fine powder metering components, causing the fine powder dosage to rely entirely on experience, making real-time data monitoring and precise control impossible. Fluctuations in the fine powder dosage not only cause an imbalance in the material concentration within the dissolution tank, affecting the efficiency of subsequent hydrolysis reactions, but also increase the risk of scaling on the inner wall of the dissolution tank due to excessive local material accumulation, which can shorten the equipment's lifespan in the long run. Meanwhile, the traditional demineralized water delivery system also suffers from a critical flaw – the lack of flow metering and control devices. As the core medium for dissolving fine oxalic acid powder, the demineralized water volume and the amount of fine powder must maintain a strict ratio. In actual production, due to the lack of flow monitoring, operators cannot promptly grasp the real-time supply of demineralized water. When the demineralized water volume is insufficient, the fine powder cannot be fully dispersed, easily forming a viscous paste. This paste can entangle the agitator blades inside the dissolving tank, causing a sudden increase in the agitator load. This can lead to abnormal equipment noise and increased energy consumption, or even cause the agitator to seize up and shut down, forcing the entire production line to stop. After each shutdown, the paste inside the tank must be manually cleaned, which not only consumes a lot of manpower and time but also generates additional material losses, significantly increasing production and operating costs. The aforementioned dual problems of lack of fine powder weighing and lack of demineralized water flow control have become core bottlenecks restricting the stability, continuity, and economy of oxalic acid production processes. Given the increasingly stringent requirements for production precision and efficiency in the current chemical industry, there is an urgent need to address the inherent shortcomings of traditional processes by constructing a new dissolution system with precise fine powder metering and controllable demineralized water flow through technological improvements. Summary of the Invention

[0003] To overcome the shortcomings of the prior art, this application provides an oxalic acid fine powder dissolving device suitable for oxalic acid plants. By setting up a fine powder silo with a weighing device, the device enables real-time monitoring and precise control of the oxalic acid fine powder dosage. It is paired with a hot salt dehydration conveying pipeline equipped with a flow control module to ensure a stable supply of desalinated water. This solves the production problems caused by the lack of weighing of fine powder and the lack of water quantity control in desalinated water in traditional processes, thereby improving the stability, continuity and economy of the oxalic acid production process.

[0004] This application provides an oxalic acid fine powder dissolving device suitable for oxalic acid plants, including an oxalic acid fine powder weighing unit, a hot salt dehydration conveying unit, and a dissolving tank. The oxalic acid fine powder weighing unit includes a fine powder silo, the inlet of which is connected to the oxalic acid fine powder outlet of the drying unit, and the outlet of which is connected to the inlet of the dissolving tank. A weighing device is provided at the bottom of the fine powder silo. The hot salt dehydration conveying unit includes a hot salt dehydration conveying pipeline. The inlet of the hot salt dehydration conveying pipeline is connected to the outlet of the hot salt dehydration unit, and the outlet of the hot salt dehydration conveying pipeline is connected to the inlet of the dissolving tank. A flow control module is installed on the hot salt dehydration conveying pipeline. The outlet of the dissolving tank is connected to the inlet of the hydrolysis mixing vessel.

[0005] Compared with existing technologies, this application solves the problem of unmetered fine powder addition and reliance on experience-based judgment in traditional processes by setting up a fine powder silo with a weighing device. This enables real-time monitoring and precise control of the fine powder addition, avoiding material concentration imbalance and equipment scaling. At the same time, the flow control module on the hot salt dehydration conveying pipeline compensates for the lack of metered control of demineralized water, ensuring a stable supply of demineralized water and preventing agitator failure due to insufficient water volume forming a paste. Ultimately, this improves the stability and continuity of the oxalic acid production process and reduces operating costs.

[0006] In one possible implementation, an external heating coil is provided on the outside of the dissolving tank. The inlet end of the external heating coil is connected to an external steam pipe, and the outlet end of the external heating coil is connected to a condensate collection tank. This application employs the above structure, which can stably supply heat via steam, improve the dissolution rate of fine powders, prevent material accumulation, ensure uniform mixing of the liquid and reduce agitator malfunctions; moreover, external heating eliminates the need to modify the internal structure of the tank, avoids the high-temperature stratification problem of traditional fluoropolymer-lined tanks, balances heating requirements with equipment lifespan, and contributes to stable and efficient production.

[0007] In one possible implementation, the dissolving tank is made of 904L stainless steel. The dissolving tank of this application uses 904L stainless steel, which, compared to the traditional 316L fluoropolymer-lined tank, offers stronger corrosion resistance and can withstand temperature changes during heating, avoiding the problem of high-temperature delamination of the fluoropolymer material, extending the tank's service life, and reducing equipment maintenance costs.

[0008] In one possible implementation, the dissolving tank includes a vessel body with a detachable cover plate, which is a flat-top cover. The dissolving tank of this application features a detachable flat-top cover plate, which, compared to traditional designs without inspection holes or with fixed top covers, allows for quick opening of the tank, facilitating personnel access for maintenance, significantly shortening maintenance time, and reducing equipment maintenance difficulty.

[0009] In one possible implementation, the outlet of the dissolving tank is further provided with a backwash port, which is connected to the hot salt dehydration conveying pipeline. This application provides a backwash port at the outlet of the dissolving tank, which is connected to the outlet of the hot salt dehydration unit. This allows for rapid flushing of residual material at the outlet using hot salt dehydration, preventing blockages and ensuring a stable delivery of the dissolved material to the hydrolysis mixing vessel, thus avoiding disruption to production continuity due to outlet blockages.

[0010] In one possible implementation, the flow control module includes a flow control valve and a flow display controller, which are electrically connected. The flow display controller is used to adjust the opening degree of the flow control valve. The flow control module of this application consists of an electrically connected flow control valve and a flow display controller. The valve opening can be adjusted via the display controller to achieve real-time monitoring and precise control of the demineralized water flow, ensuring a stable ratio with the fine powder and avoiding production problems caused by water imbalance.

[0011] In one possible implementation, the dissolving tank is equipped with a temperature controller, and the external steam pipe is equipped with a pneumatic diaphragm control valve. The temperature controller is electrically connected to the pneumatic diaphragm control valve and is used to adjust the opening degree of the pneumatic diaphragm control valve. This application's dissolving tank is equipped with a temperature controller, and the external steam pipe is equipped with a pneumatic diaphragm control valve, with the two electrically connected. The temperature controller can automatically adjust the valve opening, precisely control the steam supply, thereby stabilizing the temperature inside the dissolving tank, ensuring the efficiency and effect of fine powder dissolution, and avoiding temperature fluctuations affecting production.

[0012] In one possible implementation, the dissolving tank is equipped with a liquid level display controller. This application provides a liquid level display controller on the dissolving tank, which can monitor the liquid level of the material inside the tank in real time, preventing overflow due to excessively high levels or affecting dissolution efficiency due to excessively low levels. Simultaneously, it provides a reference for adjusting the ratio of fine powder addition and demineralized water supply, ensuring stable operation of the dissolution process. Attached Figure Description

[0013] Figure 1 This is a schematic diagram of the oxalic acid fine powder dissolving device of this application; Explanation of reference numerals in the attached figures: 11. Fine powder silo; 12. Weighing device; 21. Hot salt dehydration conveying pipeline; 31. Kettle body; 32. Cover plate; 33. Backwash port; 4. External heating coil; 5. External steam pipeline; 6. Condensate collection tank; 71. Flow control valve; 72. Flow display controller; 81. Temperature controller; 82. Pneumatic diaphragm control valve; 9. Liquid level display controller. Detailed Implementation

[0014] First, those skilled in the art should understand that these embodiments are merely used to explain the technical principles of the embodiments of this application and are not intended to limit the scope of protection of the embodiments of this application. Those skilled in the art can make adjustments as needed to adapt to specific application scenarios.

[0015] In the description of the embodiments of this application, it should be noted that, unless otherwise explicitly specified and limited, the terms "connected" and "linked" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium. Those skilled in the art can understand the specific meaning of the above terms in the embodiments of this application based on the specific circumstances.

[0016] In the embodiments of this application, unless otherwise expressly specified and limited, "above" or "below" the second feature can mean that the first feature is in direct contact with the second feature, or that the first feature is in indirect contact with the second feature through an intermediate medium. Furthermore, "above," "on top of," and "over" the second feature can mean that the first feature is directly above or diagonally above the second feature, or simply that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature can mean that the first feature is directly below or diagonally below the second feature, or simply that the first feature is at a lower horizontal level than the second feature.

[0017] The present application will now be described in further detail with reference to the accompanying drawings and specific embodiments.

[0018] like Figure 1 As shown, an oxalic acid fine powder dissolving device suitable for oxalic acid plants includes an oxalic acid fine powder weighing unit, a hot salt dehydration conveying unit, and a dissolving tank 3. The oxalic acid fine powder weighing unit includes a fine powder silo 11. The inlet of the fine powder silo 11 is connected to the oxalic acid fine powder output port of the drying unit, and the outlet of the fine powder silo 11 is connected to the feed port of the dissolving tank 3. A weighing device 12 is provided at the bottom of the fine powder silo 11. The hot salt dehydration conveying unit includes a hot salt dehydration conveying pipeline 21. The inlet of the hot salt dehydration conveying pipeline 21 is connected to the outlet of the hot salt dehydration unit, and the outlet of the hot salt dehydration conveying pipeline 21 is connected to the inlet of the dissolving tank 3. A flow control module is installed on the hot salt dehydration conveying pipeline. The outlet of the dissolving tank 3 is connected to the inlet of the hydrolysis mixing vessel. Specifically, the working principle of the oxalic acid fine powder dissolving device of this application is as follows: the oxalic acid fine powder output from the drying unit first enters the fine powder silo 11 equipped with a weighing device 12. After the weighing device 12 measures the amount of fine powder, the fine powder enters the dissolving tank 3 from the outlet of the silo. At the same time, the water from the hot salt dehydration unit enters the dissolving tank 3 through the conveying pipeline equipped with a flow control module. The flow control module adjusts the water volume to match the amount of fine powder. After the fine powder and water are mixed and dissolved in the dissolving tank 3, they are conveyed from the tank outlet to the hydrolysis mixing kettle to complete the dissolution of fine powder and the connection with subsequent processes. In a specific embodiment of this application, an external heating coil 4 is provided on the outside of the dissolving tank 3. The inlet end of the external heating coil 4 is connected to an external steam pipe 5, and the outlet end of the external heating coil 4 is connected to a condensate collection tank 6.

[0019] To address the issues of slow dissolution and easy accumulation of fine powder caused by the lack of heating in traditional dissolving tanks 3, the inlet of the external heating coil 4 on the outside of the dissolving tank 3 is connected to an external steam pipe 5. Steam can be introduced to power the coil. The steam releases heat in the coil and transfers it to the dissolving tank 3, heating the mixture of fine powder and hot salt dehydration, thereby improving the dissolution rate of fine powder and ensuring uniform mixing. At the same time, the condensate formed after the heat release flows into the condensate collection tank 6 through the coil outlet, realizing the efficient utilization of steam heat and condensate recovery, avoiding energy waste, and ultimately helping to solve the problems of low dissolution efficiency and easy agglomeration of materials in traditional processes. Furthermore, the material used for the dissolving tank 3 in this application is 904L stainless steel. Given the shortcomings of traditional 316L fluoropolymer-lined dissolving tanks 3, such as poor temperature resistance (prone to fluoropolymer delamination upon prolonged contact with steam above 80°C), limited corrosion resistance, and incompatibility with external heating modules, this application selects 904L stainless steel as the material for the dissolving tank 3. This material contains a high proportion of chromium, nickel, and molybdenum, possessing excellent chemical corrosion resistance and high-temperature stability. It can withstand the corrosive media that may be generated during the dissolution of fine oxalic acid powder and is compatible with the temperature environment of the external heating coil 4 (under steam heating conditions), preventing structural damage to the tank material due to temperature fluctuations or corrosion. Simultaneously, the structural stability of 904L stainless steel does not rely on the lining, ensuring the long-term stable operation of the dissolving tank 3 and meeting the continuous production requirements of oxalic acid. In a specific embodiment of this application, the dissolving tank 3 includes a vessel body 31, on which a cover plate 32 is detachably mounted. The cover plate 32 is a flat-topped cover. The detachable design breaks the limitations of the fixed structure, allowing operators to quickly separate the cover plate 32 from the vessel body 31 and directly open the operating space inside the tank. This facilitates entry into the tank to clean scale buildup on the inner wall, inspect the stirring components, or replace internal accessories, significantly reducing downtime for maintenance. The flat-topped cover structure avoids the drawbacks of traditional arched covers that occupy space above the tank and are inconvenient for hoisting or manual operation. At the same time, the flat-topped shape makes it easier to achieve a sealed fit with the vessel body 31, ensuring the airtightness of the material inside the tank during normal operation. This solves the traditional maintenance problems while also ensuring the stability of the production process. In practical operation, a flange connection structure can be adopted. Matching flanges are machined on the top opening edge of the vessel body 31 and the edge of the cover plate 32, respectively. Bolt holes are evenly distributed on the flanges. During assembly, a corrosion-resistant sealing gasket (such as a PTFE gasket) is installed between the two flanges. High-strength bolts and nuts that pass through the bolt holes are used to tighten the seal between the cover plate 32 and the vessel body 31. When disassembly is required, simply loosen the bolts, remove the nuts and sealing gaskets, and the cover plate 32 can be lifted away from or removed from the vessel body 31. The operation is simple and the sealing reliability is high, which is suitable for the corrosive environment and maintenance needs under oxalic acid dissolution conditions. This application also provides a backwash port 33 at the outlet of the dissolving tank 3. The backwash port is connected to the hot salt dehydration conveying pipeline 21. When there is a tendency for material residue to accumulate or slight blockage at the outlet of the dissolving tank 3, demineralized water can be introduced through the backwash port 33. The flushing force of the water flow can be used to flush the inner wall of the outlet pipeline and the residual material, so as to remove the attached solid particles and thick liquid in time and prevent the blockage from worsening. Specifically, the flow control module of this application includes a flow control valve 71 and a flow display controller 72. The flow control valve 71 and the flow display controller 72 are electrically connected, and the flow display controller 72 is used to adjust the opening degree of the flow control valve 71. A temperature controller 81 is provided on the dissolving tank 3, and a pneumatic diaphragm control valve 82 is provided on the external steam pipe 5. The temperature controller 81 is electrically connected to the pneumatic diaphragm control valve 82, and the temperature controller 81 is used to adjust the opening degree of the pneumatic diaphragm control valve 82. The flow control module of this application constructs a closed-loop control system through the electrical connection between the flow control valve 71 and the flow display controller 72. The flow display controller 72 can collect the flow data in the hot salt dehydration conveying pipeline 21 in real time and convert the data into a control signal to be transmitted to the flow control valve 71. The operator can preset the target flow rate according to the fine powder dosage. After comparing the deviation between the actual flow rate and the target flow rate, the flow display controller 72 automatically adjusts the opening of the flow control valve 71 to achieve dynamic and precise control of the demineralized water flow rate, ensuring that the demineralized water and fine powder always maintain a suitable ratio and ensuring the stability of the dissolution process. This application constructs a temperature closed-loop control system through the electrical connection between the temperature controller 81 and the pneumatic diaphragm control valve 82. The temperature controller 81 collects the temperature data of the material in the dissolution tank 3 in real time. When the temperature is lower than the preset dissolution temperature, the temperature controller 81 outputs a signal to increase the opening of the pneumatic diaphragm control valve 82, increase the steam supply of the external steam pipeline 5, and increase the temperature inside the tank; when the temperature is higher than the preset value, the valve opening is reduced to decrease the steam supply. This real-time linkage adjustment can stabilize the temperature inside the dissolving tank 3 within a suitable range for dissolving fine powder, ensuring dissolution efficiency and material uniformity, and avoiding production problems caused by temperature fluctuations. As a preferred embodiment, this application also provides a liquid level display controller 9 on the dissolving tank 3 for real-time monitoring of the liquid level in the dissolving tank 3. In the description of the embodiments of this application, it should be noted that the terms "inner" and "outer" and other terms indicating direction or positional relationship are based on the direction or positional relationship shown in the drawings. This is only for the convenience of description and does not indicate or imply that the device or component must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, it should not be construed as a limitation of this application. In the description of this application, the terms "one embodiment," "some embodiments," "in this embodiment," "specific example," or "some examples," etc., refer to specific features, structures, materials, or characteristics described in connection with that embodiment or example, which are included in at least one embodiment or example of this application. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Furthermore, without contradiction, those skilled in the art can combine and integrate different embodiments or examples and features of different embodiments or examples described in this specification. The above descriptions are merely specific embodiments of this application, but the scope of protection of this application is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. A device for dissolving fine oxalic acid powder suitable for oxalic acid production, characterized in that, It includes an oxalic acid fine powder weighing unit, a hot salt dehydration conveying unit and a dissolving tank (3). The oxalic acid fine powder weighing unit includes a fine powder silo (11). The inlet of the fine powder silo (11) is connected to the oxalic acid fine powder outlet of the drying unit. The outlet of the fine powder silo (11) is connected to the inlet of the dissolving tank (3). A weighing device (12) is provided at the bottom of the fine powder silo (11). The hot salt dehydration conveying unit includes a hot salt dehydration conveying pipe (21), the inlet of which is connected to the outlet of the hot salt dehydration unit, the outlet of which is connected to the inlet of the dissolving tank (3), and a flow control module is provided on the hot salt dehydration conveying pipe (21). The outlet of the dissolving tank (3) is connected to the inlet of the hydrolysis mixing vessel.

2. The oxalic acid fine powder dissolving device suitable for oxalic acid production facilities as described in claim 1, characterized in that, An external heating coil (4) is provided on the outside of the dissolving tank (3). The inlet end of the external heating coil (4) is connected to an external steam pipe (5), and the outlet end of the external heating coil (4) is connected to a condensate collection tank (6).

3. The oxalic acid fine powder dissolving device suitable for oxalic acid production facilities as described in claim 1, characterized in that, The material of the melting tank (3) is 904L stainless steel.

4. The oxalic acid fine powder dissolving device suitable for oxalic acid production facilities as described in claim 1, characterized in that, The dissolving tank (3) includes a vessel body (31), and a cover plate (32) is detachably provided on the vessel body (31). The cover plate (32) is a flat-top cover.

5. The oxalic acid fine powder dissolving device suitable for oxalic acid production facilities as described in claim 1, characterized in that, The outlet of the dissolving tank (3) is also provided with a backwash port (33), which is connected to the hot salt dehydration conveying pipeline (21).

6. The oxalic acid fine powder dissolving device suitable for oxalic acid production facilities as described in claim 1, characterized in that, The flow control module includes a flow control valve (71) and a flow display controller (72). The flow control valve (71) and the flow display controller (72) are electrically connected. The flow display controller (72) is used to adjust the opening degree of the flow control valve (71).

7. The oxalic acid fine powder dissolving device suitable for oxalic acid production facilities as described in claim 2, characterized in that, A temperature controller (81) is provided on the dissolving tank (3), and a pneumatic diaphragm control valve (82) is provided on the external steam pipe (5). The temperature controller (81) is electrically connected to the pneumatic diaphragm control valve (82), and the temperature controller (81) is used to adjust the opening degree of the pneumatic diaphragm control valve (82).

8. The oxalic acid fine powder dissolving device suitable for oxalic acid production facilities as described in claim 1, characterized in that, The dissolving tank (3) is equipped with a liquid level display controller (9).

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