Double-effect gas-liquid mass transfer device and assembly structure

Abstract

The utility model discloses a novel double -effect gas -liquid mass transfer device, including ascending vertical pipe and gas collecting cover, the bottom of ascending vertical pipe is provided with the liquid inlet for the reaction liquid to enter, be provided with gas injection pipe above the liquid inlet, one end of gas injection pipe is used for injecting gas, and the other end is connected with ascending vertical pipe, the gas collecting cover is the cover body of bottom open, the gas collecting cover covers the top of ascending vertical pipe the top export place's top, and the top of gas collecting cover is equipped with the porous diffuser, the utility model aims at improving the overall mass transfer efficiency of gas phase into liquid phase in the gas absorption process, and combines the principle of fluidic device and the principle of porous diffuser, thereby strengthens the double -effect mechanism of diffusion and convection mass transfer, and the mass transfer effect is greatly improved.

Description

Technical Field

[0001] This utility model belongs to the field of gas-liquid mass transfer technology, and relates to a dual-effect gas-liquid mass transfer device and its assembly structure. Background Technology

[0002] Many processes in the chemical, biotechnology, and environmental engineering industries require the dissolution of gases in liquids. This necessitates two-phase contact between the gas and liquid. As long as the liquid is not saturated with the gaseous components, the gaseous components will transfer to their dissolved state in the liquid. The mass transfer rate depends on the partial pressure of the gaseous components in the gas phase and the difference between the maximum solubility of the gas under ambient conditions and its actual solubility. When the liquid layer in contact with the gas phase becomes saturated, the mass transfer rate depends primarily on the rate of gas consumption in the process. This requires the dissolved gas to be transferred to the entire reactor volume via convection. Therefore, a common challenge in gas-to-liquid mass transfer is providing a sufficiently large interfacial area between the gas and liquid during the initial diffusion mass transfer process, while simultaneously promoting convective transport of the saturated interfacial layer to allow the gaseous components to disperse rapidly throughout the reactor volume.

[0003] The most common method for gas-liquid mass transfer is to disperse the gas into the liquid as bubbles using a diffuser. This can be achieved by pressurizing the gas and forcing it through a porous material, thus breaking the gas volume into small bubbles that then rise to the liquid surface. Another widely used method is to disperse the bubbles using an ejector. The gas is introduced into the liquid flow, where intense hydraulic mixing breaks the bubbles into even smaller ones. A third method is to disperse the bubbles using a mechanical agitator. In this case, the gas is injected near a rotating impeller, and the mechanical agitation force disperses the gas into fine bubbles and mixes them with the surrounding volume.

[0004] The existing technology has the following disadvantages: (1) The use of porous diffusers causes the partial pressure of the gas inside the bubble to reach equilibrium with the liquid phase interface layer quickly. The mixing energy provided by the rising bubble is small, resulting in low overall mass transfer efficiency. This results in a large amount of unused gas components being released into the space above the liquid surface as exhaust gas. In order to utilize the remaining gas components in the exhaust gas, the diluted gas can be recompressed and dispersed back into the liquid. However, the low partial pressure of the gas components leads to a further reduction in mass transfer efficiency, so this approach is not economical in most applications. (2) The typical use of jet injectors is to pump the reactor liquid into the jet injector through a side flow pump and mix it with the gas. This produces a highly saturated gas-liquid mixture, but the gas-liquid contact time is short, and it is then immediately discharged into the main reactor. The generated bubble size is larger than that of porous diffusers, so the rising speed is faster. Although the method of adding gas using a side flow jet injector has a high convective mass transfer effect, the volume of the mixture entering the main reactor is often limited by the available mixing energy. (3) Using mechanical agitators for gas dispersion requires a high specific energy requirement, so it is only suitable for smaller reactor volumes. Utility Model Content

[0005] Purpose of the utility model: The purpose of this utility model is to address the above-mentioned problems by providing a dual-effect gas-liquid mass transfer device and its assembly structure. This device can be submerged and installed in a reactor, and is suitable for large reaction tanks with a liquid level depth exceeding 3 meters.

[0006] Technical solution: This utility model provides a dual-effect gas-liquid mass transfer device, including a rising riser and a gas collecting hood. The bottom end of the rising riser is provided with a liquid inlet for the reaction liquid to enter. A gas injection pipe is provided above the liquid inlet. One end of the gas injection pipe is used to inject gas, and the other end is connected to the rising riser. The gas collecting hood is an open-bottomed hood that covers the top outlet of the rising riser. A porous diffuser is provided on the top of the gas collecting hood.

[0007] The operating principle is as follows: Gas is injected into the riser and mixes thoroughly with the liquid in the reactor. Due to the density difference, the gas-liquid mixture flows upward under the action of the gas lift pump. Thorough mixing of gas and liquid in the riser allows the gas components to rapidly reach saturation in the liquid phase. The gas-liquid mixture is then discharged to the space below the gas collection hood. Due to the increased cross-sectional area here, the effective downward flow velocity decreases to a certain extent, causing the rarefied gas bubbles to separate and accumulate in the top space of the gas collection hood. The gas at the top of the gas collection hood is forced out through the porous diffuser at the top of the reactor vessel under the hydrostatic pressure. The gas is released at the top of the equipment in the form of fine bubbles and rises towards the liquid surface in the reactor. The rising bubbles above the equipment form an overall upward suction flow in the surrounding area. Liquid containing saturated gas is released from the bottom of the gas collection hood into the surrounding reactor volume. Because the fluid as a whole exhibits an upward suction flow, this liquid containing saturated gas mixes with the surrounding reactor liquid, thus ensuring that the dissolved gas is transferred to the entire reactor volume through convection. Two-stage mass transfer rapidly saturates the liquid phase in the side stream, after which the dissolved gas is convectively distributed throughout the reactor volume via this mixed flow. Meanwhile, the sparse gas phase is distributed into the reactor via a slow gas mass transfer mechanism dominated by diffusion, unaffected by the high saturation barrier surrounding the bubbles.

[0008] Furthermore, the length between the bottom end of the riser and the bottom end of the gas collection hood is the immersion length H3, and the total length of the riser is H2. The ratio of the immersion length to the total length of the riser is H3 / H2 = 0.5-0.7. This ensures constant flow rate and efficient mixing.

[0009] Furthermore, the height of the riser from its bottom to the gas injection pipe is H4, and the ratio of the height of the riser from its bottom to the gas injection pipe to the total length of the riser is H4 / H2 = 0.2-0.3. This ensures that an initial upward flow is formed when gas injection begins.

[0010] Furthermore, the diameter of the gas collecting hood is D2, the diameter of the rising riser is D1, and the ratio of the diameters of the gas collecting hood and the riser is D2 / D1 = 3-7.

[0011] Another technical solution of this utility model is a dual-effect gas-liquid mass transfer device assembly structure, which includes multiple dual-effect gas-liquid mass transfer devices, and the gas injection pipes of multiple dual-effect gas-liquid mass transfer devices are connected to the gas supply main pipe to form a set of assembly structures.

[0012] Furthermore, the system includes multiple sets of assembly structures, with gas injection and discharge occurring alternately in each set of assembly structures, thereby achieving periodic gas injection through multiple sets of assembly structures.

[0013] Furthermore, the ratio of the average gas flow rate to the injected gas flow rate of the porous diffuser is 0.2-0.6, enabling direct switching of the injected flow rate between groups. Taking two groups of devices as an example, the time of the gas injection phase is equal to the gas emission time when there is no gas injection. In this case, gas injection can be switched between multiple groups.

[0014] Compared with existing technologies, this invention has the following advantages: 1. This invention achieves high-intensity gas-liquid mixing initially through the jet principle, and then releases fine bubbles through a diffuser to distribute them throughout the entire reactor volume, achieving a superior high-diffusion mass transfer effect. Furthermore, it utilizes the advantages of convective mass transfer to achieve efficient gas-liquid mass transfer through a single device. This improves the overall gas-liquid mass transfer effect and reduces energy consumption and operating costs, making it suitable for large-scale gas-liquid mass transfer applications.

[0015] 2. By using a reasonable diameter ratio between the gas collection hood and the riser, the downward surface velocity of the liquid within the gas collection hood is limited, and bubble separation (bubble diameter greater than 0.5 mm) is ensured. Smaller bubbles are carried by the released saturated liquid and further promote the mass transfer process during convective gas transport. Attached Figure Description

[0016] Figure 1 (a) is a side view of the dual-effect gas-liquid mass transfer device of Example 1; Figure 1 (b) is a top view of the dual-effect gas-liquid mass transfer device of Embodiment 1 of this utility model.

[0017] Figure 2 (a) is a side view of the dual-effect gas-liquid mass transfer device of Example 2; Figure 2 (b) is a top view of the dual-effect gas-liquid mass transfer device of Embodiment 2 of this utility model.

[0018] Figure 3 This is a schematic diagram of the operating cycle of the device of this utility model.

[0019] Figure 4 This is a schematic diagram of the assembly structure of multiple dual-effect gas-liquid mass transfer devices.

[0020] Figure 5 An example diagram of a double-effect gas-liquid mass transfer device installed in a reactor.

[0021] Figure 6 A grouping example diagram of a dual-effect gas-liquid mass transfer device in a reactor. Detailed Implementation

[0022] The technical solution of this utility model will be further described below with reference to the accompanying drawings.

[0023] Example 1

[0024] like Figure 1As shown, this embodiment of a dual-effect gas-liquid mass transfer device includes a gas collecting hood 3, a rising riser 1 with a gas injection pipe 2, and a porous diffuser 4. The bottom end of the rising riser 1 is provided with a liquid inlet for liquid entry, and the gas injection pipe 2 is located above the liquid inlet. One end of the gas injection pipe 2 is used to inject gas, and the other end is connected to the rising riser 1. The gas collecting hood 3 is an open-bottomed hood that covers the top outlet of the rising riser 1, forming a top space for gas. The top of the gas collecting hood 3 is provided with a porous diffuser 4.

[0025] Example 2

[0026] like Figure 2 As shown, based on Embodiment 1, this embodiment provides a dual-effect gas-liquid mass transfer device, including a gas collecting hood 3 (height H1, diameter D2), a rising riser 1 (length H2, diameter D1), a gas injection pipe 2 located at height H4, and a porous diffuser 4 (diameter D3). The length between the bottom end of the rising riser 1 and the bottom end of the gas collecting hood 3 is the immersion length H3, and the ratio of the immersion length H3 to the total length H2 of the rising riser is between H3 / H2 = 0.5 and 0.7. The ratio of the gas injection height H4 (measured from the bottom) to the total length H2 of the rising riser is between H4 / H2 = 0.2 and 0.3. The diameter ratio of the gas collecting hood diameter D2 to the rising riser diameter D1 is between D2 / D1 = 3 and 7.

[0027] Example 3

[0028] The operating cycle of the double-effect gas-liquid mass transfer device is shown: like Figure 3 As shown in (a), in stage A, the gas collection hood 3 and the riser 1 are filled with the reaction liquid. At this time, no gas is injected into the gas injection pipe 2, no liquid flows into the riser 1 from the liquid inlet 5 at the bottom of the riser, and no bubbles are discharged from the porous diffuser 4.

[0029] like Figure 3 As shown in (b), in stage B, gas 6 is injected into gas injection pipe 2, and fresh reaction liquid enters riser 1 from liquid inlet 5 at the bottom of riser 1, and enters gas collection hood 3 in the form of saturated liquid 7. The saturated liquid 7 in gas collection hood 3 is gradually replaced by depleted gas 8 and discharged into the reactor, where it mixes with reactor liquid 9. The depleted gas 8 in gas collection hood 3 is discharged into the reactor from porous diffuser 4 in the form of fine bubbles 10.

[0030] like Figure 3As shown in (c), in stage C, gas injection stops in gas injection pipe 2, and fresh reaction liquid no longer enters riser 1 from the inlet 5 at the bottom of riser 1. The depleted gas 8 in gas collection hood 3 continues to be discharged into the reactor from porous diffuser 4 in the form of fine bubbles 10. The depleted gas 8 in gas collection hood 3 is replaced by the rising liquid level 11, and reactor liquid enters from the bottom 301 of gas collection hood 3. When the depleted gas 8 in gas collection hood 3 is completely discharged, the device is filled with reactor liquid, reaching the state of stage A.

[0031] Example 4

[0032] like Figure 4 As shown in the figure, this embodiment illustrates the assembly structure of a double-effect gas-liquid mass transfer device, which consists of multiple double-effect gas-liquid mass transfer devices arranged in a group. The gas injection pipes 2 of each of the multiple double-effect gas-liquid mass transfer devices are all connected to the main gas supply pipe 12. The multiple devices can be installed in pairs or in more groups, and the installation range covers part or all of the bottom area of ​​the reactor.

[0033] Example 5

[0034] like Figure 5 As shown in the figure, this embodiment illustrates the structure of a double-effect gas-liquid mass transfer device 100 installed in a reactor 200. The reactor 200 is filled with reaction liquid 201 to a liquid level 203, and a gas top space 202 exists. The liquid level height h of the reaction liquid 201 is [not specified]. l For distances greater than 3 meters, h is preferred. l >4 meters.

[0035] Example 6

[0036] like Figure 6 As shown in the illustration, this embodiment demonstrates an example of the grouping of a dual-effect gas-liquid mass transfer device 100 within a reactor 200. The device is divided into three groups: Group 1 (210), Group 2 (220), and Group 3 (230). An example sequence of operation phases is shown: Group 1 (210) is in startup phase A, Group 2 (220) is in gas injection phase B, and Group 3 (230) is in gas emission phase C. Each phase has the same duration, and at the end of each phase, the phases are swapped in a clockwise direction.

Claims

1. A dual-effect gas-liquid mass transfer device, characterized in that, The device includes a riser and a gas collection hood. The bottom end of the riser is provided with an inlet for the reaction liquid to enter. A gas injection pipe is provided above the inlet. One end of the gas injection pipe is used to inject gas, and the other end is connected to the riser. The gas collection hood is an open-bottomed hood that covers the top outlet of the riser. The top of the gas collection hood is provided with a porous diffuser.

2. The dual-effect gas-liquid mass transfer device according to claim 1, characterized in that, The length between the bottom end of the riser and the bottom end of the gas collection hood is the immersion length H3, the total length of the riser is H2, and the ratio of the immersion length to the total length of the riser is: H3 / H2 = 0.5-0.

7.

3. The dual-effect gas-liquid mass transfer device according to claim 1, characterized in that, The height of the riser from its bottom end to the gas injection pipe is H4, and the ratio of the height of the riser from its bottom end to the gas injection pipe to the total length of the riser is: H4 / H2 = 0.2-0.

3.

4. The dual-effect gas-liquid mass transfer device according to claim 1, characterized in that, The diameter of the gas collection hood is D2, the diameter of the rising riser is D1, and the ratio of the diameters of the gas collection hood and the riser is D2 / D1 = 3-7.

5. An assembly structure for a dual-effect gas-liquid mass transfer device according to any one of claims 1-4, characterized in that, It includes multiple dual-effect gas-liquid mass transfer devices, and the gas injection pipes of the multiple dual-effect gas-liquid mass transfer devices are connected to the gas supply main pipe to form a set of assembly structures.

6. The assembly structure of the dual-effect gas-liquid mass transfer device according to claim 5, characterized in that, It includes multiple sets of the assembly structures described above.

7. The assembly structure of the dual-effect gas-liquid mass transfer device according to claim 6, characterized in that, The ratio of the average gas flow rate to the injected gas flow rate of the porous diffuser is 0.2-0.6.

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