A shell-and-tube evaporator for acetic acid production

Abstract

The utility model relates to acetic acid technical field proposes a kind of column pipe type evaporator for acetic acid production, including shell, the evaporation subassembly is installed in shell interior, fixedly connected with fixed box on the bellows, the recovery subassembly is installed in the fixed box bottom, the feeding subassembly is installed in the reaction bin interior, evaporation subassembly is made after secondary steam by secondary steam pipe into the reaction bin interior, feeding subassembly works, by feeding pipe one and send in ethylene, by feeding pipe and send in oxygen, so that raw materials are reacted in the reaction bin interior and generated acetic acid, by recovery pipe and send gaseous acetic acid into fixed box, by liquid inlet pipe and add liquid to bellows interior, water in bellows is changed into steam by heat exchange and sent into shell, liquid acetic acid is entered into recovery tank by collection pipe, and subsequent heat is recycled and utilized, reduce production cost. Through the above technical scheme, the problem that waste heat cannot be utilized after acetic acid production in the prior art is solved.

Description

Technical Field

[0001] This utility model relates to the field of acetic acid technology, specifically to a tubular evaporator for acetic acid production. Background Technology

[0002] Acetic acid, also known as acetic acid, is widely distributed in nature. For example, it exists as ethyl acetate in fruits, vegetables, and vegetable oils, as a free acid in animal tissues, excrement, and blood. It can also be produced by the fermentation of other organic matter in microorganisms. Anhydrous acetic acid is often referred to as "glacial acetic acid," a colorless, hygroscopic liquid with a freezing point of 16.6 °C (62 °F). After solidification, it forms colorless crystals. Its aqueous solution is weakly acidic and highly corrosive, and its vapor is irritating to the eyes and nose.

[0003] The direct gas-phase oxidation synthesis of ethylene uses a palladium-based catalyst. Ethylene, oxygen, and steam react in a fixed-bed reactor at 150–160°C and approximately 0.9 MPa to produce acetic acid. This method requires relatively low equipment investment, is suitable for small-scale production plants, and generates minimal wastewater.

[0004] Acetic acid produced by the direct gas-phase oxidation synthesis of ethylene is mainly in gaseous or gas-liquid mixed state. However, after subsequent processing and cooling, liquid acetic acid can be obtained. Acetic acid evaporator is required for production. However, existing evaporators are prone to heat loss during use and are not easy to recover and reuse, resulting in energy waste. Utility Model Content

[0005] This invention proposes a tubular evaporator for acetic acid production, which solves the problem of unutilized waste heat after acetic acid production in related technologies.

[0006] The technical solution of this utility model is as follows: A shell-and-tube evaporator for acetic acid production includes a shell, an evaporation assembly installed inside the shell, a steam connection pipe fixedly connected to the right end of the shell, a corrugated pipe fixedly connected to the end of the steam connection pipe, a fixed box fixedly connected to the corrugated pipe, and a recovery assembly installed at the bottom of the fixed box;

[0007] A reaction chamber is located above the outer shell, and a feeding assembly is installed inside the reaction chamber.

[0008] Preferably, the evaporation assembly includes an isolation plate one, which is fixedly connected inside the outer shell, and a heat exchange tube is fixedly connected to the top of the isolation plate one, and an isolation plate two is fixedly connected to the top of the heat exchange tube.

[0009] Preferably, a drain pipe is fixedly connected to the bottom of the outer shell, a raw material liquid pipe is fixedly connected to the left end of the outer shell above the second isolation plate, and a condenser pipe is fixedly connected to the left end of the outer shell near the top of the first isolation plate.

[0010] Preferably, the recycling assembly includes a support plate, the bottom of the fixed box is fixedly connected to the support plate, the bottom of the support plate is fixedly connected to a support column, the bottom of the support column is fixedly connected to a base plate, the top center of the base plate is fixedly installed with a recycling box, and the bottom of the fixed box is fixedly connected to a collection pipe extending into the inside of the recycling box.

[0011] Preferably, the feeding assembly includes a secondary steam pipe, which is fixedly connected to the top of the outer shell. The end of the secondary steam pipe extends into the interior of the reaction chamber, and a shut-off valve is fixedly installed on the secondary steam pipe. A recovery pipe is fixedly connected to the right end of the reaction chamber, and the end of the recovery pipe extends into the interior of the fixed box. A shut-off valve is fixedly installed on the recovery pipe.

[0012] Preferably, a feed pipe 1 extending into the interior of the reaction chamber is fixedly connected to the top of the reaction chamber, and a feed pipe 2 extending into the interior of the reaction chamber and located to the right of the feed pipe 1 is fixedly connected to the top of the reaction chamber.

[0013] Preferably, the end of the corrugated pipe extends to the right side of the fixed box and is fixedly connected to an inlet pipe.

[0014] Preferably, there are several heat exchange tubes, and the multiple heat exchange tubes are arranged in a circular array between the first isolation plate and the second isolation plate.

[0015] The working principle and beneficial effects of this utility model are as follows:

[0016] 1. In this utility model, by setting up a heat recovery component, the waste heat of the acetic acid generated inside the reaction chamber is utilized through heat exchange via a corrugated pipe. This facilitates the cooling of gaseous acetic acid, reduces production costs, and effectively improves resource utilization. Compared with traditional production equipment, the addition of a waste heat recovery device reduces the cost of raw material production. At the same time, it cools the acetic acid after production. If a high concentration of acetic acid is required, the cooled acetic acid can be collected through a recovery box, facilitating subsequent separation and purification steps. Compared with traditional equipment, the cooling steps are reduced, allowing the waste heat to be fully utilized.

[0017] 2. In this utility model, by setting up an evaporation component, when the heating medium is introduced into the pipe for heating, the relative density of the liquid in the heat exchange tube is smaller than that in the central circulation tube because the heating area of ​​the liquid per unit volume in the heat exchange tube is larger than that in the central circulation tube. This results in a density difference between the liquid in the heat exchange tube and the liquid in the central circulation tube. This density difference causes the solution to flow naturally from the central circulation tube down and then up through the heat exchange tube. The device has the advantages of compact structure, convenient manufacturing and reliable operation. Attached Figure Description

[0018] The present invention will now be described in further detail with reference to the accompanying drawings and specific embodiments.

[0019] Figure 1 This is a schematic diagram of the overall external structure of this utility model;

[0020] Figure 2 This is a schematic diagram of the main cross-sectional structure of this utility model;

[0021] Figure 3 This is a schematic diagram of the evaporation component structure of this utility model;

[0022] Figure 4 This is a schematic diagram of the feeding assembly structure of this utility model;

[0023] Figure 5 This is a schematic diagram of the structure of the recycling component of this utility model.

[0024] In the diagram: 1. Outer shell; 2. Reaction chamber; 3. Fixed box; 4. Evaporation assembly; 41. Raw material liquid pipe; 42. Drain pipe; 43. Heat exchange pipe; 44. Condenser pipe; 45. Isolation plate one; 46. Isolation plate two; 5. Steam connection pipe; 6. Feed assembly; 61. Secondary steam pipe; 62. Feed pipe one; 63. Feed pipe two; 64. Recovery pipe; 65. Shut-off valve one; 66. Shut-off valve two; 7. Liquid inlet pipe; 8. Corrugated pipe; 9. Recovery assembly; 91. Base plate; 92. Recovery box; 93. Support column; 94. Support plate; 95. Collection pipe. Detailed Implementation

[0025] The technical solutions of this utility model will be clearly and completely described below with reference to the embodiments of this utility model. Obviously, the described embodiments are only some embodiments of this utility model, and not all embodiments. Based on the embodiments of this utility model, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of this utility model.

[0026] Example 1

[0027] like Figures 1-5As shown, this embodiment proposes a shell-and-tube evaporator for acetic acid production, including a shell 1, an evaporation assembly 4 installed inside the shell 1, a steam connection pipe 5 fixedly connected to the right end of the shell 1, the evaporation connection pipe 5 connecting a corrugated pipe 8 and the shell 1, facilitating the use of steam, so that the steam generated after the waste heat of acetic acid is recovered and reused is sent into the shell 1, the end of the steam connection pipe 5 is fixedly connected to a corrugated pipe 8, the corrugated pipe 8 is generally S-shaped, with a larger outer surface area than a straight pipe, and a larger contact area with the gas inside the fixed box 3, facilitating heat exchange and increasing heat exchange efficiency, the fixed box 3 is fixedly connected to the corrugated pipe 8, and a recovery assembly 9 is installed at the bottom of the fixed box 3; reaction chamber 2, reaction... The reaction chamber 2 is located above the outer shell 1. The reaction chamber 2 provides a high-pressure and high-temperature environment for the acetic acid reaction. The feed assembly 6 is installed inside the reaction chamber 2. The end of the corrugated pipe 8 extends to the right side of the fixed box 3 and is fixedly connected to the liquid inlet pipe 7. Water is added to the inside of the corrugated pipe 8 through the feed pipe 7 to facilitate subsequent heat exchange. The outer shell 1 and its internal evaporation assembly 4 are a central circulation tube evaporator. The structure of the central circulation tube evaporator is that its heating chamber is composed of a vertical heat exchange tube 43 (heat exchange tube 43 bundle of boiling tubes). In the center of the tube bundle, there is a tube with a larger diameter, called the central circulation tube. Its cross-sectional area is generally 40% to 100% of the total cross-sectional area of ​​the heat exchange tube 43 bundle. When the heating medium is introduced into the pipe fittings, the relative density of the liquid in the heat exchange tube 43 is lower than that in the central circulation tube because the heating area per unit volume of liquid in the heat exchange tube 43 is greater than that in the central circulation tube. This creates a density difference between the liquid in the heat exchange tube 43 and the liquid in the central circulation tube. This density difference causes the solution to circulate naturally, descending from the central circulation tube and then rising again through the heat exchange tube 43. The circulation speed of the solution depends on the density difference and the length of the tube; the greater the density difference and the longer the tube, the greater the circulation speed. However, due to the overall height limitation, the heat exchange tube 43 of this type of evaporator is relatively short, typically 1–2 m, with a diameter of 25–75 mm.

[0028] Furthermore, the recycling component 9 includes a support plate 94. The bottom of the fixed box 3 is fixedly connected to the support plate 94, and the bottom of the support plate 94 is fixedly connected to a support column 93. The bottom of the support column 93 is fixedly connected to a base plate 91, providing a platform for placing the recycling box 92 to facilitate subsequent collection of acetic acid. The recycling box 92 is fixedly installed at the top center of the base plate 91. After gaseous acetic acid enters the fixed box 3, due to the high temperature and high pressure environment during acetic acid production, subsequent recycling requires cooling. The bottom of the fixed box 3 is fixedly connected to a collection pipe 95 extending into the recycling box 92. Gaseous acetic acid is fed into the fixed tank 3 through the recovery pipe, and liquid is added into the corrugated pipe 8 through the liquid inlet pipe 7. The acetic acid undergoes heat exchange through the corrugated pipe 8, turning from gaseous to liquid. The water in the corrugated pipe 8 turns into steam and is sent into the outer shell 1. The liquid acetic acid enters the recovery tank 92 through the collection pipe 95, where the subsequent heat is recovered and utilized, reducing energy waste and production costs. While reducing the processing cost of steam raw materials, the acetic acid is cooled. If high-concentration acetic acid is required, the cooled acetic acid is collected through the recovery tank 92 for subsequent separation and purification steps.

[0029] Furthermore, the feeding assembly 6 includes a secondary steam pipe 61. The secondary steam pipe 61 is fixedly connected to the top of the outer shell 1, and its end extends into the interior of the reaction chamber 2. The secondary steam pipe 61 connects the outer shell 1 and the reaction chamber 2, facilitating the addition of steam to the interior of the reaction chamber 2. A shut-off valve 65 is fixedly installed on the secondary steam pipe 61. A recovery pipe 64 is fixedly connected to the right end of the reaction chamber 2, connecting the reaction chamber 2 and the fixed box 3, facilitating the flow of acetic acid after the reaction to the recovery box 92 for cooling. The end of the recovery pipe 64 extends into the interior of the fixed box 3, and a shut-off valve 66 is fixedly installed on the recovery pipe 64. The shut-off valve is an H21X check valve, mainly used in gas pipelines to prevent gas backflow. It is suitable for water, oil, liquids, and gases. The reaction chamber 2 is equipped with pipelines for air, CNG natural gas, hydrogen, etc. A feed pipe 62 extending into the interior of the reaction chamber 2 is fixedly connected to the top of the chamber. Ethylene is fed into the reaction chamber 2 through feed pipe 62. Ethylene's density is slightly less than air. Oxygen is fed into the reaction chamber 2 through feed pipe 63. In still air, considering only gravity, ethylene tends to rise, while oxygen sinks slightly, facilitating the mixing of raw materials. A feed pipe 63 extending into the interior of the reaction chamber 2 and located to the right of feed pipe 62 is also fixedly connected to the top of the reaction chamber 2. When the feeding assembly 6 is operational, ethylene is fed through feed pipe 62, and oxygen is fed through feed pipe 63. Using a palladium-based catalyst at suitable temperature and pressure, ethylene, oxygen, and steam react inside the reaction chamber 2 to produce acetic acid, providing suitable reaction conditions for acetic acid formation.

[0030] In this embodiment, after the evaporation component 4 generates secondary steam, it enters the reaction chamber 2 through the secondary steam pipe 61. The feeding component 6 operates, feeding ethylene through the first feeding pipe 62 and oxygen through the first feeding pipe 63. Using a palladium-based catalyst, under suitable temperature and pressure, ethylene, oxygen, and steam react inside the reaction chamber 2 to produce acetic acid. The second shut-off valve 66 is opened, and the gaseous acetic acid is sent into the fixed tank 3 through the recovery pipe 64. Liquid is added into the bellows 8 through the liquid inlet pipe 7. The acetic acid undergoes heat exchange through the bellows 8, turning from gaseous to liquid. The bellows 8 heats up, causing the added liquid to absorb heat and turn into steam. The steam is then sent into the outer shell 1 through the steam connection pipe 5. When inside the recovery tank 92... When the temperature is insufficient, steam can be directly introduced through the liquid inlet pipe 7 to facilitate the circulation of steam in subsequent production. Liquid acetic acid enters the recovery tank 92 through the collection pipe 95 to recover and utilize subsequent heat, reducing energy waste and production costs. While reducing the processing cost of steam raw materials, it also cools ethylene. If high-concentration acetic acid is required, the cooled acetic acid is collected through the recovery tank 92 to facilitate subsequent separation and purification steps. Compared with traditional production equipment, the addition of a waste heat recovery device reduces the cost of raw material production. At the same time, it cools the produced acetic acid, reducing the acetic acid cooling step compared with traditional equipment, allowing the waste heat to be fully utilized.

[0031] Example 2

[0032] like Figures 1-3As shown, based on the same concept as Embodiment 1 above, this embodiment also proposes an evaporation assembly 4 including an isolation plate 45. The isolation plate 45 is fixedly connected inside the outer shell 1, determining the positions of the heat exchange tube 43 and the central circulation tube to facilitate subsequent secondary evaporation of steam. The heat exchange tube 43 is fixedly connected to the top of the isolation plate 45, and the isolation plate 46 is fixedly connected to the top of the heat exchange tube 43. A drain pipe 42 is fixedly connected to the bottom of the outer shell 1. When it is necessary to clean the inside of the outer shell 1, the solution inside the outer shell 1 is discharged through the drain pipe 42 to facilitate subsequent cleaning. A raw material liquid pipe 41 is fixedly connected to the left end of the outer shell 1 and above the isolation plate 46. The raw material liquid is added to the inside of the outer shell 1. After being heated by the liquid inside the heat exchange tube 43, the relative density of the liquid inside the heat exchange tube 43 is small, thereby creating a density difference between the liquid inside the heat exchange tube 43 and the liquid inside the central circulation tube. This density difference causes the solution to flow from the central circulation tube... The solution flows naturally downwards and then upwards through heat exchange tube 43. The circulation speed of the solution depends on the density difference generated by the solution and the length of the tube. The greater the density difference and the longer the tube, the greater the circulation speed of the solution. A condenser tube 44 is fixedly connected to the left end of the outer shell 1 and near the top of the isolation plate 45. After heat exchange with the raw liquid inside the heat exchange tube 43, the steam liquefies into liquid and can be discharged through the drain pipe 42. At the same time, it can be recycled to reduce the waste of water resources. There are several heat exchange tubes 43, which are arranged in a circumferential array between the isolation plate 45 and the second isolation plate 46. The raw liquid is added through the raw material liquid pipe 41, and the steam enters through the steam connection pipe 5. When the raw liquid is inside the heat exchange tube 43, the steam transfers heat to raise the temperature of the heat exchange tube 43, heats the raw liquid inside to generate steam, and then enters the reaction chamber 2 to react and produce acetic acid, providing the necessary conditions for the production of acetic acid.

[0033] In this embodiment, the evaporation component 4 is in operation. The raw liquid is added through the raw liquid pipe 41. The corrugated pipe 8 generates steam by exchanging heat with the acetic acid produced in the reaction. The steam enters the shell 1 through the steam connection pipe 5. When the raw liquid is inside the heat exchange pipe 43, the steam transfers heat, causing the heat exchange pipe 43 to heat up and generate secondary steam. The secondary steam is then sent to the rear through the secondary steam pipe 61. After releasing heat, the original steam condenses into water droplets and is discharged through the condenser pipe 44, providing the necessary conditions for the production of acetic acid. The device has the advantages of compact structure, convenient manufacturing and reliable operation. At the same time, the solution inside the shell 1 circulates up and down.

[0034] The above are merely preferred embodiments of the present utility model and are not intended to limit the present utility model. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present utility model shall be included within the protection scope of the present utility model.

Claims

1. A tubular evaporator for acetic acid production, characterized in that, Includes an outer shell (1), an evaporation assembly (4) is installed inside the outer shell (1), a steam connection pipe (5) is fixedly connected to the right end of the outer shell (1), a corrugated pipe (8) is fixedly connected to the end of the steam connection pipe (5), a fixed box (3) is fixedly connected to the corrugated pipe (8), and a recovery assembly (9) is installed at the bottom of the fixed box (3). The reaction chamber (2) is located above the outer shell (1), and the feeding assembly (6) is installed inside the reaction chamber (2).

2. The tubular evaporator for acetic acid production according to claim 1, characterized in that, The evaporation assembly (4) includes an isolation plate one (45), an isolation plate one (45) is fixedly connected inside the outer shell (1), a heat exchange tube (43) is fixedly connected to the top of the isolation plate one (45), and an isolation plate two (46) is fixedly connected to the top of the heat exchange tube (43).

3. A tubular evaporator for acetic acid production according to claim 2, characterized in that, The bottom of the outer shell (1) is fixedly connected to a drain pipe (42), the left end of the outer shell (1) and above the second isolation plate (46) is fixedly connected to a raw material liquid pipe (41), and the left end of the outer shell (1) and near the top of the first isolation plate (45) is fixedly connected to a condenser pipe (44).

4. A tubular evaporator for acetic acid production according to claim 1, characterized in that, The recycling assembly (9) includes a support plate (94), the bottom of the fixed box (3) is fixedly connected to the support plate (94), the bottom of the support plate (94) is fixedly connected to the support column (93), the bottom of the support column (93) is fixedly connected to the bottom plate (91), the recycling box (92) is fixedly installed at the top center of the bottom plate (91), and the bottom of the fixed box (3) is fixedly connected to a collection pipe (95) extending into the recycling box (92).

5. A tubular evaporator for acetic acid production according to claim 1, characterized in that, The feeding assembly (6) includes a secondary steam pipe (61). The secondary steam pipe (61) is fixedly connected to the top of the outer shell (1). The end of the secondary steam pipe (61) extends into the interior of the reaction chamber (2). A shut-off valve (65) is fixedly installed on the secondary steam pipe (61). A recovery pipe (64) is fixedly connected to the right end of the reaction chamber (2). The end of the recovery pipe (64) extends into the interior of the fixed box (3). A shut-off valve (66) is fixedly installed on the recovery pipe (64).

6. A tubular evaporator for acetic acid production according to claim 1, characterized in that, The top of the reaction chamber (2) is fixedly connected to a feed pipe 1 (62) extending into the interior of the reaction chamber (2), and the top of the reaction chamber (2) is fixedly connected to a feed pipe 2 (63) extending into the interior of the reaction chamber (2) and located to the right of the feed pipe 1 (62).

7. A tubular evaporator for acetic acid production according to claim 1, characterized in that, The end of the corrugated pipe (8) extends to the right side of the fixed box (3) and is fixedly connected to the liquid inlet pipe (7).

8. A tubular evaporator for acetic acid production according to claim 2, characterized in that, There are several heat exchange tubes (43), and the multiple heat exchange tubes (43) are arranged in a circular array between the first isolation plate (45) and the second isolation plate (46).

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