A thin-film evaporation device for fuming sulfuric acid

Abstract

This utility model relates to a thin-film evaporation device for fuming sulfuric acid, comprising an upper chamber, a middle chamber, and a lower chamber. The upper chamber has a sulfur trioxide gas outlet at its top and a nicotinic acid inlet pipe on its side wall. A dispersion disk is located below the output end of the nicotinic acid inlet pipe within the upper chamber. The dispersion disk has a number of liquid flow holes and an upwardly extending gas phase pipe. A tube sheet is located below the dispersion disk, and a number of lower liquid heat exchange tubes are distributed on the tube sheet. An overflow groove is provided around the upper periphery of each lower liquid heat exchange tube and the tube sheet. The lower liquid heat exchange tubes pass through the middle chamber and their lower ends directly connect to the lower chamber. This device helps eliminate the risk of air-liquid conditions, improves evaporation capacity, and ensures a continuous, low-consumption, and safe evaporation process.

Description

Technical Field

[0001] This utility model relates to a thin-film evaporation device for fuming sulfuric acid. Background Technology

[0002] Fuming sulfuric acid (oleum) is a solution of sulfuric acid (H2SO4) with excess sulfur trioxide (SO3) dissolved in it. It is a key raw material for the production of high-purity sulfuric acid and sulfur trioxide (SO3). Its evaporation process requires gas-liquid separation through a thin-film evaporation device.

[0003] Traditional equipment often employs a tube-plate liquid distribution structure, where liquid is distributed from the top tube plate to the inner wall of vertically arranged heat exchange tubes to form a falling film, which is then heated and evaporated using high-temperature flue gas or steam. However, this structure has significant drawbacks under the conditions of high-viscosity, highly corrosive fuming sulfuric acid. The core problem lies in the air-liquid phenomenon caused by uneven liquid distribution (i.e., local liquid film rupture forming dry wall zones). The inherent defects of the tube-plate structure have become the core bottleneck restricting the efficient and stable operation of fuming sulfuric acid thin-film evaporation equipment.

[0004] Existing improvement methods cannot achieve a continuous and uniform distribution of the liquid film under high viscosity and heat-sensitive conditions. Therefore, a new type of liquid distribution structure is urgently needed. Utility Model Content

[0005] The purpose of this invention is to provide a thin-film evaporation device for fuming sulfuric acid, which helps to eliminate the risk of air-liquid contamination and improves evaporation processing capacity.

[0006] The technical solution of this utility model is as follows: a thin-film evaporation device for fuming sulfuric acid, comprising an upper cavity, a middle cavity, and a lower cavity. The top of the upper cavity is provided with a sulfur trioxide gas outlet, and the side wall of the upper cavity is provided with a nicotinic acid inlet pipe. A dispersion disk is provided in the upper cavity below the output end of the nicotinic acid inlet pipe. A certain number of liquid flow holes and an upwardly extending gas phase pipe are distributed on the dispersion disk. A tube sheet is provided below the dispersion disk. A certain number of lower liquid heat exchange tubes are distributed on the tube sheet. An overflow groove is provided between the upper periphery of each lower liquid heat exchange tube and the tube sheet. The lower liquid heat exchange tube passes through the middle cavity and its lower end is directly connected to the lower cavity.

[0007] Furthermore, the liquid flow holes on the dispersion plate are positioned to avoid the upper port of the lower liquid heat exchange tube on the tube sheet.

[0008] Furthermore, the flow holes are distributed circumferentially around the outer ring of the overflow groove on the tube sheet on the dispersion plate.

[0009] Furthermore, the dispersion disc is a circular disc-shaped structure with a surrounding edge, and there is a gap between the surrounding edge of the dispersion disc and the side wall of the upper cavity. The lower end of the dispersion disc is fixed to the upper side of the tube sheet by several support rods.

[0010] Furthermore, the nicotinic acid inlet pipe enters the upper cavity through the side wall of the upper cavity. The nicotinic acid inlet pipe has an arc-shaped pipe section with the output port facing downward in the upper cavity. A flow divider is provided between the arc-shaped pipe section and the dispersion plate.

[0011] Furthermore, the nicotinic acid inlet pipe is provided with a suspension rod connected to the top of the central cavity at the pipe section that penetrates into the central cavity; the diverter plate is an inverted disc structure and is connected to the arc-shaped pipe section via a fixing rod.

[0012] Furthermore, the top of the upper cavity is provided with a pressure gauge port, a safety valve port, and an observation mirror.

[0013] Furthermore, a heat medium inlet pipe is provided on the upper side wall of the middle cavity, and a heat medium outlet pipe is provided on the lower side wall of the middle shell.

[0014] Furthermore, a drain pipe is provided at the bottom of the lower cavity, a nicotinic acid outlet pipe and a nicotinic acid overflow outlet pipe are provided on the two side walls of the upper part of the lower cavity, and a thermometer port is also provided on the two side walls of the middle part of the lower cavity.

[0015] Furthermore, the upper cavity includes an upper shell, the middle cavity includes a middle shell, and the lower cavity includes a lower shell. The upper and lower ends of the middle shell are respectively covered with a tube plate and a sealing plate, so that the interior of the upper shell, the interior of the middle shell, and the interior of the lower shell form the upper cavity, the middle cavity, and the lower cavity.

[0016] Compared with the prior art, the present invention has the following advantages:

[0017] 1. This device helps eliminate the risk of air-liquid imbalance, improves evaporation capacity, and ensures a continuous, low-consumption, and safe evaporation process.

[0018] 2. An overflow groove is formed between the outlet of the lower liquid heat exchange tube and the tube sheet in this device. Fuming sulfuric acid flows from the tube sheet first around the overflow groove of the lower liquid heat exchange tube, and then overflows into the lower liquid heat exchange tube. This can better ensure that different lower liquid heat exchange tubes can be filled with liquid, while reducing corrosion between the tube sheet and the weld.

[0019] 3. The dispersion disc and tube sheet of this device are equipped with flow holes to prevent splashing during descent and reduce the generation of acid mist. Attached Figure Description

[0020] Figure 1 This is a schematic diagram of the structure of this utility model;

[0021] Figure 2 This is a cross-sectional view of the present invention;

[0022] Figure 3 This is an enlarged view of the dispersion disc, tube sheet, and lower liquid heat exchange tube of this utility model.

[0023] Figure 4This is a partially enlarged view of the fit between the liquid-filled heat exchange tube and the tube sheet of this utility model;

[0024] Figure 5 This is a top view schematic diagram showing the distribution of the flow holes on the dispersion plate of this utility model;

[0025] In the diagram: 10-Upper cavity 11-Sulfur trioxide gas outlet 12-Upper shell 13-Pressure gauge port 14-Safety valve port 15-Observation mirror 20-Middle cavity 21-Middle shell 22-Heating medium inlet pipe 23-Heating medium outlet pipe 24-Sealing plate 30-Lower cavity 31-Lower shell 32-Drain pipe 33-Nicotinic acid outlet pipe 34-Nicotinic acid overflow pipe 35-Thermometer port 40-Nicotinic acid inlet pipe 41-Arc-shaped tube section 42-Hanging rod 50-Dispersion plate 51-Liquid flow hole 52-Gas phase pipe 53-Side rim 54-Gap 55-Support rod 60-Tube sheet 61-Overflow groove 70-Lower liquid heat exchange tube 80-Diverter plate 81-Fixing rod. Detailed Implementation

[0026] To make the above-mentioned features and advantages of this utility model more easily understood, specific embodiments are described below in conjunction with the accompanying drawings, but this utility model is not limited thereto.

[0027] refer to Figures 1 to 5

[0028] A thin-film evaporation device for fuming sulfuric acid includes an upper cavity 10, a middle cavity 20, and a lower cavity 30. The upper cavity has a sulfur trioxide gas outlet 11 at its top and a nicotinic acid inlet pipe 40 on its side wall. A dispersion disk 50 is located below the output end of the nicotinic acid inlet pipe within the upper cavity. The dispersion disk has a number of liquid flow holes 51 and upward-extending gas phase pipes 52. A tube sheet 60 is located below the dispersion disk, and a number of lower liquid heat exchange tubes 70 are distributed on the tube sheet. The upper end of each lower liquid heat exchange tube is flush with the upper surface of the tube sheet, and an overflow groove 61 is provided around the upper periphery of each tube and between the tube sheet, allowing the fuming sulfuric acid to flow into the overflow groove and then evenly into the lower liquid heat exchange tubes. The middle cavity has a heat medium supply structure, and the lower liquid heat exchange tubes pass through the middle cavity with their lower ends directly connected to the lower cavity.

[0029] In this embodiment, the upper cavity includes an upper shell 12, the middle cavity includes a middle shell 21, and the lower cavity includes a lower shell 31. The upper and lower ends of the middle shell are respectively covered by a tube plate and a sealing plate 24, so that the interior of the upper shell, the interior of the middle shell, and the interior of the lower shell form the upper cavity, the middle cavity, and the lower cavity.

[0030] In this embodiment, to prevent fuming sulfuric acid from falling directly into the lower liquid heat exchange tube, the flow holes on the dispersion plate are positioned to avoid the upper port of the lower liquid heat exchange tube on the tube sheet. Specifically, the top-view projection of the flow holes on the dispersion plate is distributed circumferentially around the outer ring of the overflow groove on the tube sheet, so that the fuming sulfuric acid first falls onto the tube sheet and then flows into the overflow groove, allowing the fuming sulfuric acid to flow downward in a uniform film in the lower liquid heat exchange tube.

[0031] In this embodiment, the dispersion disk is a circular disk-shaped structure with a surrounding edge 53, so that the fuming sulfuric acid can be dispersed to various parts of the bottom plate of the dispersion disk. There is a gap 54 between the surrounding edge of the dispersion disk and the side wall of the upper cavity. The lower end of the dispersion disk is fixed to the upper side of the tube sheet by several support rods 55.

[0032] In this embodiment, the nicotinic acid inlet pipe is inserted into the upper cavity through the side wall of the upper shell. The nicotinic acid inlet pipe has an arc-shaped pipe section 41 with the output port facing downward in the upper cavity. A flow divider 80 is provided between the arc-shaped pipe section and the dispersion plate so that the fuming sulfuric acid can be evenly distributed to the dispersion plate.

[0033] In this embodiment, the nicotinic acid inlet pipe is provided with a hanger 42 connected to the top of the middle cavity at the pipe portion that penetrates into the middle cavity, thereby fixing the nicotinic acid inlet pipe.

[0034] In this embodiment, the diverter plate is an inverted disc structure (with an arc surface on the top) and is connected to the arc-shaped tube section via a fixing rod 81, so that the diverter plate is suspended below the output port of the nicotinic acid inlet pipe.

[0035] In this embodiment, a pressure gauge port 13, a safety valve port 14, and an observation mirror 15 are provided at the top of the upper cavity. A remote pressure gauge is installed through the pressure gauge port.

[0036] In this embodiment, a heat medium inlet pipe 22 is provided on the upper sidewall of the middle cavity, and a heat medium outlet pipe 23 is provided on the lower sidewall of the middle shell. Heat medium vapor enters through the heat medium inlet pipe to provide heat to the lower liquid heat exchange tube for heat exchange evaporation of fuming sulfuric acid. After the heat exchange evaporation process, the heat medium forms vapor condensate and is discharged from the heat medium outlet pipe.

[0037] In this embodiment, a drain pipe 32 is provided at the bottom of the lower cavity, and a nicotinic acid outlet pipe 33 and a nicotinic acid overflow outlet pipe 34 are provided on the upper two side walls of the lower cavity to output 16% fuming sulfuric acid (fuming sulfuric acid whose solubility is reduced by evaporation); thermometer ports 35 are also provided on the middle two side walls of the lower cavity to facilitate the installation of a remote thermometer.

[0038] In this embodiment, the bottom surface of the tube sheet and the periphery of the lower liquid heat exchange tube can be connected by welding.

[0039] In this embodiment, the upper cavity, middle cavity, lower cavity, and their components can be made of corrosion-resistant and high-temperature-resistant materials, respectively.

[0040] Working process: Fuming sulfuric acid (24% concentration) flows into the upper cavity through the nicotinic acid inlet pipe. The fluid is evenly distributed onto the dispersion plate by the distribution plate, flows through the flow holes onto the tube sheet, and then flows through the overflow groove on the tube sheet into the lower liquid heat exchange tube that connects directly to the lower shell section. The fluid flows downward in a uniform film along the lower liquid heat exchange tube. During the downward flow of the fluid, it is heated and vaporized by the heat medium, and the generated sulfur trioxide (SO3) vapor rises into the upper cavity, passes through the vapor phase tube of the dispersion plate, and is then discharged through the sulfur trioxide gas outlet to enter the next process.

[0041] If this utility model discloses or relates to mutually fixedly connected parts or structural components, then unless otherwise stated, a fixed connection can be understood as: a detachable fixed connection (e.g., using bolts or screws) or a non-detachable fixed connection (e.g., riveting or welding). Of course, mutually fixed connections can also be replaced by an integral structure (e.g., manufactured using a casting process) (except where it is obviously impossible to use an integral forming process).

[0042] In addition, unless otherwise stated, the terms used to indicate positional relationships or shapes in any of the technical solutions disclosed in this utility model above include states or shapes that are similar to, close to, or approximate with them.

[0043] Any component provided by this utility model can be assembled from multiple individual components, or it can be a single component manufactured by a one-piece molding process.

[0044] The above description is only a preferred embodiment of the present utility model. All equivalent changes and modifications made within the scope of the patent application of the present utility model shall be covered by the present utility model.

Claims

1. A thin film evaporation apparatus for oleum comprising an upper chamber, a middle chamber and a lower chamber, characterized in that, The upper cavity has a sulfur trioxide gas outlet at the top and a nicotinic acid inlet pipe on the side wall. A dispersion plate is located below the output end of the nicotinic acid inlet pipe in the upper cavity. A certain number of liquid flow holes and upward-extending gas phase pipes are distributed on the dispersion plate. A tube sheet is located below the dispersion plate. A certain number of lower liquid heat exchange tubes are distributed on the tube sheet. An overflow groove is provided around the upper periphery of each lower liquid heat exchange tube and the tube sheet. The lower liquid heat exchange tubes pass through the middle cavity and their lower ends are directly connected to the lower cavity.

2. A thin film evaporation apparatus for oleum according to claim 1, characterized in that The liquid flow holes on the dispersion plate are positioned to avoid the upper port of the lower liquid heat exchange tube on the tube sheet.

3. A thin film evaporation apparatus for oleum according to claim 1 or 2, characterized in that The flow holes are distributed circumferentially around the outer ring of the overflow groove on the tube sheet on the dispersion plate.

4. A thin film evaporation apparatus for oleum according to claim 1 or 2, characterized in that The dispersion disc is a circular disc-shaped structure with a surrounding edge. There is a gap between the surrounding edge of the dispersion disc and the side wall of the upper cavity. The lower end of the dispersion disc is fixed to the upper side of the tube sheet by several support rods.

5. A thin film evaporation apparatus for oleum according to claim 1, wherein The nicotinic acid inlet pipe enters the upper cavity through the side wall of the upper cavity. The nicotinic acid inlet pipe is located in the upper cavity with an arc-shaped pipe section having an output port facing downwards. A flow divider is provided between the arc-shaped pipe section and the dispersion plate.

6. A thin film evaporation apparatus for oleum according to claim 5, characterized in that The nicotinic acid inlet pipe is connected to the top of the central cavity by a suspension rod at the pipe section that enters the central cavity; the diverter plate is an inverted disc structure and is connected to the arc-shaped pipe section by a fixing rod.

7. A thin film evaporation apparatus for smokable sulphuric acid according to claim 1, 2, 5 or 6, characterized in that The top of the upper cavity is equipped with a pressure gauge port, a safety valve port, and an observation mirror.

8. A thin film evaporation apparatus for oleum according to claim 1, characterized in that The upper sidewall of the middle cavity is provided with a heat medium inlet pipe, and the lower sidewall of the middle shell is provided with a heat medium outlet pipe.

9. A thin film evaporation apparatus for oleum according to claim 1, 2, 5, 6 or 8, characterized in that The bottom of the lower cavity is provided with a drain pipe, the upper two side walls of the lower cavity are provided with nicotinic acid outlet pipe and nicotinic acid overflow outlet pipe, and the middle two side walls of the lower cavity are also provided with thermometer ports.

10. A thin film evaporation apparatus for oleum according to claim 1, characterized in that The upper cavity includes an upper shell, the middle cavity includes a middle shell, and the lower cavity includes a lower shell. The upper and lower ends of the middle shell are respectively covered with a tube plate and a sealing plate, so that the interior of the upper shell, the interior of the middle shell, and the interior of the lower shell form the upper cavity, the middle cavity, and the lower cavity.

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