Efficient washing, desulfurizing and purifying device for biogas engineering

Abstract

The utility model relates to an efficient washing, desulfurizing and purifying device for biogas engineering, which comprises a tower frame and a two-section type absorption tower arranged on the tower frame, and the two-section type absorption tower comprises a lower bubbling tower section and an upper spraying tower section; a gas outlet is formed in the top of the upper spray tower section, and an upper liquid inlet is formed in the side part of the upper spray tower section; an air inlet is formed in the side part of the lower bubbling tower section, a liquid outlet is formed in the bottom of the lower bubbling tower section, and a middle liquid inlet is also formed between the lower bubbling tower section and the upper spraying tower section; the lower bubbling tower section and the upper spraying tower section are respectively and independently fed; and a hole disc type distributor and a groove type distributor are sequentially arranged in the upper spray tower section from top to bottom. The device disclosed by the utility model has the advantages that two-section absorption, bottom bubble tower absorption and upper spray tower absorption are adopted, and the diameter of the tower can be reduced under the same treatment gas quantity, so that the one-time investment of equipment is reduced.

Description

Technical Field

[0001] This utility model relates to a high-efficiency washing, desulfurization and purification device for biogas projects, belonging to the field of purification. Background Technology

[0002] Biogas purification mainly involves removing hydrogen sulfide from biogas to meet national fuel standards. Currently, biogas desulfurization and purification methods at home and abroad are mainly divided into: alkaline washing method, biological method, and complexed iron method.

[0003] The complexed iron desulfurization technology is a wet oxidation method for removing hydrogen sulfide using complexed iron as a catalyst. Its characteristic is that it directly converts H2S in the gas into elemental sulfur. It is a new type of desulfurization technology with simple process, high working sulfur capacity, and environmental protection and non-toxicity. It overcomes the drawbacks of traditional desulfurization processes such as low sulfur capacity, complex desulfurization process, high by-product salt generation rate, and serious environmental pollution. The sulfur recovery rate reaches 99%, which can meet the ever-increasing environmental protection indicators.

[0004] The complexed iron method uses a complexing agent as the absorbent, which is non-toxic, does not pollute the environment, and is recyclable. This not only saves on adsorbent but also reduces the cost of biogas desulfurization (compared to subtractive and biological methods). Traditional complexed iron desulfurization absorption towers are bubble columns, with a large liquid-to-gas ratio to facilitate the full absorption of key components in the gas phase. However, this also brings some problems:

[0005] 1. The most important equipment for desulfurization of complexed iron is the scrubbing absorption tower. In China, bubbling towers are commonly used for absorption. The upper part of the scrubbing tower is unfilled, and the top of the tower is a wire mesh demister. The hydrogen sulfide content in biogas varies greatly, typically ranging from 7000ppm to 20000ppm (for biogas from leachate of municipal solid waste).

[0006] 2. Due to the absorption characteristics of the bubble tower for desulfurization of complexed iron, a large amount of water is required and the liquid level at the bottom of the tower is required to be very high, which leads to a large gas pressure loss. In order to reduce the impact of the large pressure loss, traditional bubble towers usually adopt the method of increasing the diameter. The most direct impact is that the tower equipment volume increases, and the cost often increases several times. Therefore, the traditional equipment tower with a single-section design has great drawbacks.

[0007] 3. As a crucial internal component of the absorption tower, the liquid distributor's function is to uniformly distribute or redistribute the liquid at the top of the packing or at a certain height, thereby increasing the effective surface area for mass transfer, improving interphase contact, and ultimately enhancing the tower's efficiency. However, existing washing bubble towers lack distributors altogether, relying solely on simple nozzles at the top, resulting in poor liquid distribution. Furthermore, due to variations in gas flow, the liquid volume increases, exceeding the spray density of traditional absorption towers relative to the tower diameter. Therefore, traditional liquid distributors often employ sieve plate distributors or floating raft distributors with large single-aperture holes. The most direct engineering approach is to increase the orifice diameter to reduce the possibility of flooding. The large orifice diameter directly leads to uneven liquid distribution, manifesting as wall-attached and offset flow, directly reducing absorption efficiency.

[0008] 4. The liquid flow within the packing layer is not a uniform plunger flow, but rather exhibits channeling, deflection, and wall flow phenomena. This leads to amplification and end effects in the packed tower. While structured packing can maximize the specific surface area, its biggest problem is uneven liquid distribution. Random packing, although achieving good liquid distribution, suffers from a smaller specific surface area. Therefore, existing scrubbing towers are often bulky, essentially a way to increase the volume of the packing to address these issues. This directly results in extremely high equipment investment, increased difficulty in packing construction, and complex maintenance. Utility Model Content

[0009] To overcome the shortcomings of existing technologies, this utility model provides a high-efficiency scrubbing, desulfurization, and purification device for biogas projects. The technical solution of this utility model is as follows:

[0010] A high-efficiency scrubbing and desulfurization purification device for biogas engineering includes a tower and a two-stage absorption tower installed on the tower. The two-stage absorption tower includes a lower bubbling tower section and an upper spraying tower section. A gas outlet is provided at the top of the upper spraying tower section, and an upper liquid inlet is provided on the side. An air inlet is provided on the side of the lower bubbling tower section, and a liquid outlet is provided at the bottom. A middle liquid inlet is also provided between the lower bubbling tower section and the upper spraying tower section. The lower bubbling tower section and the upper spraying tower section are fed independently. A perforated plate distributor and a trough distributor are arranged sequentially from top to bottom in the upper spraying tower section.

[0011] A structured packing layer is installed at the bottom of the perforated disc distributor; a random packing layer is installed at the bottom of the trough distributor; the structured packing layer and the random packing layer are alternately arranged.

[0012] The liquid volume in the lower bubbling tower section is more than four times that in the upper spraying tower section.

[0013] The cross-sectional area of ​​the riser pipe of the perforated distributor is less than 10% of the cross-sectional area of ​​the upper spray tower section, so as to match the gas velocity requirements of the upper tower section.

[0014] A rectangular gas distributor is also provided at the bottom of the lower bubbling tower section. The diameter of the rectangular gas distributor is 3-5 mm, and the spacing between the distribution holes is 2-3 times the diameter of the hole.

[0015] The upper spray tower section is also equipped with an anti-fog entrainment unit, which includes a wire mesh demister installed at the top of the tower and a liquid return pipe connected to the wire mesh demister.

[0016] The ratio of the diameter of the lower bubbling tower section to the diameter of the upper spraying tower section is 1:0.6-0.8.

[0017] The advantages of this utility model are:

[0018] 1. The two-stage absorption system, with bottom bubbling tower absorption and upper spray tower absorption, allows for a reduction in tower diameter while maintaining the same gas throughput, thereby reducing initial equipment investment.

[0019] 2. A combination of random and structured packing is used. This maximizes the gas-liquid contact area while ensuring uniform liquid distribution and avoiding wall flow, which causes uneven distribution of the gas and liquid phases within the packing layer.

[0020] 3. The combination of grooved disc distributor and perforated disc distributor is used to solve the problem of uneven distribution of gas and liquid phases in the tower, such as flow deviation, and improve the absorption effect.

[0021] 4. The use of a rectangular gas distributor can prevent scaling and clogging, thus extending its service life.

[0022] 5. Safe and reliable, with a long service life. In addition, the equipment has protection measures against overpressure and mist entrainment, and is easy to install, use and maintain. Attached Figure Description

[0023] Figure 1 This is a schematic diagram of the main structure of this utility model. Detailed Implementation

[0024] The present invention will be further described below with reference to specific embodiments, and the advantages and features of the present invention will become clearer as a result of the description. However, these embodiments are merely exemplary and do not constitute any limitation on the scope of the present invention. Those skilled in the art should understand that modifications or substitutions can be made to the details and form of the technical solution of the present invention without departing from the spirit and scope of the present invention, but all such modifications and substitutions fall within the protection scope of the present invention.

[0025] See Figure 1 This utility model relates to a high-efficiency scrubbing and desulfurization purification device for biogas engineering, including a tower and a two-section absorption tower installed on the tower. The two-section absorption tower includes a lower bubbling tower section 12 and an upper spray tower section 11. A gas outlet 1 is provided at the top of the upper spray tower section, and an upper liquid inlet 3 is provided on the side. An air inlet 9 is provided on the side of the lower bubbling tower section, and a liquid outlet 10 is provided at the bottom. A middle liquid inlet 8 is also provided between the lower bubbling tower section and the upper spray tower section. The lower bubbling tower section 12 and the upper spray tower section 11 are fed independently. A perforated plate distributor 4 and a trough distributor 6 are arranged sequentially from top to bottom in the upper spray tower section 11.

[0026] Based on the above structural design, the following advantages are achieved:

[0027] 1. Two-stage absorption tower design reduces equipment investment.

[0028] Structural optimization: By dividing the absorption tower into a lower bubbling tower section (12) and an upper spray tower section (11), with two independent feed sections (middle liquid inlet 8 and upper liquid inlet 3), the liquid-to-gas ratio requirement of a single tower section is significantly reduced.

[0029] Reduced tower diameter: Traditional bubble columns require larger tower diameters due to large liquid volumes, but this design, through segmented absorption, can reduce the tower diameter for the same throughput, significantly reducing equipment volume and material costs.

[0030] 2. Highly efficient gas-liquid distribution design enhances absorption efficiency.

[0031] Combination of perforated disc and trough distributors: The upper spray tower section (11) adopts a combination of perforated disc distributor (4) and trough distributor (6). The cross-sectional area of ​​the riser pipe of the perforated disc distributor is less than 10% (to adapt to high gas velocity). The trough distributor optimizes the trough width and spacing to ensure uniform liquid distribution and reduce the phenomenon of flow deviation and wall-attached flow.

[0032] Packing layer optimization: The structured packing layer (large specific surface area) and the random packing layer (uniform distribution) are alternately set to balance the gas-liquid contact area and distribution uniformity, avoid channeling or wall flow in the packing layer, and improve mass transfer efficiency.

[0033] 3. Anti-clogging and long lifespan design

[0034] Rectangular gas distributor: The bottom of the lower bubbling tower section (12) adopts a rectangular gas distributor (9) with an aperture of 3-5mm. Compared with the traditional tubular distributor, it can avoid the blockage problem caused by sulfur precipitation and extend the equipment operation cycle.

[0035] 4. Enhance operational flexibility and stability

[0036] Segmented control: Two independent feeding stages allow for flexible adjustment of liquid volume according to working conditions (the liquid volume in the lower stage is more than 4 times that in the upper stage), adapting to fluctuations in hydrogen sulfide concentration and improving operational flexibility.

[0037] Anti-fog entrainment: A wire mesh demister (combined with a liquid return pipe) is installed at the top of the upper spray tower section to effectively reduce fog entrainment and ensure the purification quality of the gas outlet (1).

[0038] 5. Overall cost and environmental advantages

[0039] Reduced energy consumption: Improved gas-liquid distribution uniformity reduces pressure loss and energy consumption; packing combination design reduces packing volume and lowers maintenance costs.

[0040] Environmental compatibility: The desulfurization method using complexed iron has a sulfur recovery rate of up to 99%, and the non-toxic absorbent is recyclable, meeting environmental protection requirements.

[0041] Through structural innovation (two-stage absorption tower, combined distributor, and mixed packing) and functional optimization (anti-clogging design and segmented control), while ensuring efficient desulfurization, it significantly reduces equipment investment and operating costs, and improves operational stability and environmental performance, making it suitable for biogas purification scenarios with high hydrogen sulfide concentrations.

[0042] A structured packing layer 5 is installed at the lower part of the perforated disc distributor 4; a random packing layer 7 is installed at the lower part of the trough distributor 6; the structured packing layer 5 and the random packing layer 7 are alternately arranged. The structured packing (large specific surface area) provides sufficient gas-liquid contact area, while the random packing (uniformly distributed) reduces liquid segregation and wall flow phenomena. The alternating arrangement of the two maximizes mass transfer efficiency and ensures uniform liquid distribution; it also provides strong resistance to fluctuations: the alternating structure mitigates the impact of gas-liquid flow fluctuations on the packing layer, avoids channeling or local dead zones, and improves operational stability. The combination of the easy replacement of the random packing and the high efficiency of the structured packing reduces long-term maintenance costs.

[0043] The liquid volume of the lower bubbling tower section 12 is more than four times that of the upper spraying tower section 11.

[0044] The cross-sectional area of ​​the riser pipe of the perforated disc distributor 4 is less than 10% of the cross-sectional area of ​​the upper spray tower section to accommodate the gas velocity requirements of the upper tower section. The upper spray tower section has a higher gas velocity (due to the reduced hydrogen sulfide concentration), and the smaller cross-section of the riser pipe increases the gas flow rate, prevents gas short-circuiting, and reduces pressure drop. The small cross-section of the riser pipe forces the gas to pass evenly through the distribution holes, forming a counter-current contact with the liquid spray of the perforated disc distributor, thus enhancing the mass transfer effect.

[0045] A rectangular gas distributor is also provided at the bottom of the lower bubbling tower section 12. The diameter of the rectangular gas distributor is 3-5mm, and the spacing between the distribution holes is 2-3 times the diameter. Compared with the traditional tubular distributor, the rectangular layout reduces the risk of sulfur precipitates accumulating in the channels. The 3-5mm diameter ensures both uniform gas distribution and anti-clogging ability.

[0046] The upper spray tower section is also equipped with an anti-fogging unit 2, which includes a wire mesh demister installed at the top of the tower and a liquid return pipe connected to the wire mesh demister. The wire mesh demister captures liquid droplets entrained in the gas through inertial impaction and surface tension, and the hydrogen sulfide content of the purified gas (outlet 1) meets the standard. The liquid return pipe guides the captured sulfur-containing liquid back to the system for reprocessing, reducing absorbent waste and lowering operating costs.

[0047] The ratio of the diameter of the lower bubbling tower section 12 to the diameter of the upper spraying tower section 11 is 1:0.6-0.8. The lower bubbling tower section has a larger diameter to meet the high liquid volume requirements of the bubbling reaction; the upper spraying tower section has a smaller diameter to meet the high gas velocity requirements of the spraying section and reduce the equipment volume. The optimized tower diameter ratio distributes the pressure drop between the two sections, avoiding excessive local pressure drop that could lead to increased energy consumption and improving overall energy efficiency.

[0048] This utility model discloses a high-efficiency scrubbing and desulfurization purification device for biogas engineering. Based on a two-stage absorption tower design, it combines gas-liquid distribution optimization with packing material combination technology to achieve efficient removal of hydrogen sulfide. The detailed working principle is as follows:

[0049] 1. Biogas pretreatment and preliminary desulfurization (lower bubbling tower section)

[0050] Gas distribution and bubbling reaction:

[0051] Biogas containing a high concentration of hydrogen sulfide (7000-20000ppm) enters the bottom of the lower bubbling tower section 12 through the air inlet 9 and is evenly dispersed into fine bubbles through a rectangular gas distributor (orifice diameter 3-5mm, orifice spacing 2-3 times the orifice diameter).

[0052] Anti-clogging design: The rectangular layout and reasonable orifice size prevent sulfur precipitates from clogging the gas and ensure uniform gas distribution.

[0053] High-efficiency mass transfer: The bubbles are in full contact with the high liquid volume (more than 4 times the liquid volume of the upper part) of the complexed iron absorption liquid, and the sulfide is rapidly oxidized to elemental sulfur in the bubbling reaction;

[0054] Liquid level control and pressure drop optimization:

[0055] The lower section of the tower has a larger diameter (tower diameter ratio 1:0.6-0.8) to meet high liquid volume requirements, reduce gas velocity to reduce pressure loss, and discharge sulfur-rich absorbent through outlet 10 to maintain system circulation.

[0056] 2. Refined desulfurization and gas-liquid distribution (upper spray tower section)

[0057] Segmented feeding and countercurrent contact:

[0058] After preliminary desulfurization, the gas rises to the upper spray tower section 11, where it forms a countercurrent contact with a small amount of absorbent injected from the middle inlet 8 and the upper inlet 3.

[0059] Orifice-type distributor 4: The cross-sectional area of ​​the riser pipe is less than 10%, which is suitable for high gas velocity (due to the reduction of hydrogen sulfide concentration), forcing the gas to pass through the distribution holes evenly and avoiding gas short circuit.

[0060] 6. Optimizes tank width and spacing to ensure uniform liquid spraying and eliminates flow deviation or wall-adhering phenomena.

[0061] Synergistic effect of packing layer:

[0062] The gas passes sequentially through the structured packing layer 5 (high specific surface area) and the random packing layer 7 (uniformly distributed), with the two layers alternating.

[0063] Structured packing: maximizes the gas-liquid contact area and improves mass transfer efficiency.

[0064] Random packing: Reduces channeling and wall flow phenomena, and mitigates the effects of gas-liquid fluctuations.

[0065] This combination design balances efficiency and stability, ensuring that residual hydrogen sulfide is further absorbed.

[0066] 3. Gas-liquid separation and resource recovery

[0067] Anti-fog and droplet entrainment unit:

[0068] The purified gas passes through the top wire mesh demister (anti-fog entrainment unit 2), which uses inertial collision and surface tension to capture entrained droplets, ensuring that the outlet gas (gas outlet 1) meets national gas standards.

[0069] Liquid reflux: The captured sulfur-containing droplets are returned to the system via a liquid reflux pipe, enabling the absorption agent to be recycled and reducing operating costs.

[0070] 4. System Optimization and Overall Benefits

[0071] Energy consumption and pressure drop balance:

[0072] The two-section tower diameter ratio (1:0.6-0.8) optimizes the gas-liquid flow pattern, reduces local pressure drop, and reduces energy consumption; at the same time, the packing combination design reduces the packing volume and reduces maintenance difficulty.

[0073] Operational flexibility and environmental compatibility:

[0074] Two independent feed stages allow for flexible adjustment of liquid volume based on fluctuations in hydrogen sulfide concentration (as shown by dynamic adjustment of liquid volume below), adapting to different operating conditions; the complexed iron method is non-toxic and has a high sulfur recovery rate, meeting environmental protection requirements.

[0075] This invention is applicable to scenarios with high hydrogen sulfide concentrations, such as biogas from leachate of municipal solid waste and biogas from agricultural waste, and combines technological advancement with economic efficiency.

[0076] The above description is only a preferred embodiment of the present utility model, but the protection scope of the present utility model is not limited thereto. Any equivalent substitutions or changes made by those skilled in the art within the technical scope disclosed in the present utility model, based on the technical solution and the inventive concept of the present utility model, should be included within the protection scope of the present utility model.

Claims

1. A high-efficiency scrubbing, desulfurization, and purification device for biogas projects, characterized in that, The system includes a tower and a two-section absorption tower mounted on the tower. The two-section absorption tower comprises a lower bubbling tower section and an upper spray tower section. A gas outlet is provided at the top of the upper spray tower section, and an upper liquid inlet is provided on the side. An air inlet is provided on the side of the lower bubbling tower section, and a liquid outlet is provided at the bottom. A middle liquid inlet is also provided between the lower bubbling tower section and the upper spray tower section. The lower bubbling tower section and the upper spray tower section are fed independently. A perforated plate distributor and a trough distributor are arranged sequentially from top to bottom in the upper spray tower section.

2. The high-efficiency scrubbing, desulfurization, and purification device for biogas projects according to claim 1, characterized in that, A structured packing layer is installed at the bottom of the perforated disc distributor; a random packing layer is installed at the bottom of the trough distributor; the structured packing layer and the random packing layer are alternately arranged.

3. The high-efficiency scrubbing, desulfurization, and purification device for biogas projects according to claim 1 or 2, characterized in that, The liquid volume in the lower bubbling tower section is more than four times that in the upper spraying tower section.

4. The high-efficiency scrubbing, desulfurization, and purification device for biogas projects according to claim 3, characterized in that, The cross-sectional area of ​​the riser pipe of the perforated distributor is less than 10% of the cross-sectional area of ​​the upper spray tower section.

5. The high-efficiency scrubbing, desulfurization, and purification device for biogas projects according to claim 4, characterized in that, A rectangular gas distributor is also provided at the bottom of the lower bubbling tower section. The diameter of the rectangular gas distributor is 3-5 mm, and the spacing between the distribution holes is 2-3 times the diameter of the hole.

6. The high-efficiency scrubbing, desulfurization, and purification device for biogas projects according to claim 5, characterized in that, The upper spray tower section is also equipped with an anti-fog entrainment unit, which includes a wire mesh demister installed at the top of the tower and a liquid return pipe connected to the wire mesh demister.

7. The high-efficiency scrubbing, desulfurization, and purification device for biogas projects according to claim 6, characterized in that, The ratio of the diameter of the lower bubbling tower section to the diameter of the upper spraying tower section is 1:0.6-0.8.

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