A hierarchical absorption tower group for absorbing NMP tail gas

Abstract

The utility model belongs to waste gas recovery technical field especially relates to a kind of hierarchical absorption tower tower group of absorbing NMP tail gas, by setting up spray system, using the spray nozzle of venturi pipe with contraction-throat-expansion structure, can enhance spray atomization effect, let droplet evenly disperse, greatly strengthen gas-liquid contact, effectively improve initial absorption efficiency;First absorption tower packing area is provided with matched stirring assembly, can actively agitate packing, reduce the situation that NMP polymer adheres and deposits, reduce jam from the source;Three-stage absorption tower connection structure of hierarchical cooperation, further strengthen overall processing effect.The overall design has the advantages of improving processing efficiency, reducing maintenance downtime, reducing packing jam, and ensuring stable and efficient NMP tail gas treatment.

Description

Technical Field

[0001] This utility model belongs to the technical field of exhaust gas absorption towers, and in particular relates to a staged absorption tower group for absorbing NMP exhaust gas. Background Technology

[0002] The tail gas absorption tower is a key piece of equipment used to absorb N-methylpyrrolidone (NMP) waste gas. The waste gas passes through a multi-concentration absorption tower group, and gas-liquid contact is achieved in the spray system and packing zone of each tower to achieve efficient tail gas absorption. However, due to the physical properties of NMP, under the high concentration and high temperature conditions of the first absorption tower, a large amount of undissolved gas accumulates in the lower tower body. At this time, NMP is prone to polymerization, and the viscous properties of NMP polymer make it easy to adhere to the surface of the packing zone in the lower tower body (similar to asphalt deposits), which will cause packing blockage over time.

[0003] Because packing blockage directly affects the normal operation of the absorption tower and the efficiency of waste gas treatment, the packing needs to be cleaned regularly. The current cleaning procedure involves workers using a crane to remove the packing from the packing layer through a container at the working window of the absorption tower. The packing is then transported outside for cleaning before being placed back into the packing layer. This method not only requires frequent shutdowns for cleaning, consuming a significant amount of time, but also significantly impacts production efficiency. Utility Model Content

[0004] The purpose of this invention is to provide a staged absorption tower assembly for absorbing NMP tail gas, aiming to solve the technical problems in the prior art of reducing maintenance downtime and preventing packing blockage and spray nozzle blockage.

[0005] To achieve the above objectives, this utility model provides a staged absorption tower assembly for absorbing NMP tail gas, comprising a first absorption tower, a second absorption tower, and a third absorption tower. Each of the first, second, and third absorption towers is equipped with a spray system and two packing zones, which are arranged from top to bottom as a first packing zone and a second packing zone. The spray system includes spray pipes and spray nozzles. Spray systems are provided at the top of both the first and second packing zones. The spray nozzles of the first absorption tower are Venturi nozzles with a contraction section, a throat, and an expansion section. The first and second packing zones include packing support grids, packing material, and packing pressure plates. The second packing zone of the first absorption tower is equipped with a stirring assembly for agitating the packing material.

[0006] Furthermore, the packing pressure plate of the second packing zone is provided with a stirring assembly, which includes three straight blades and a rotating shaft. The upper end of the rotating shaft is provided with a bevel gear, and the three straight blades are located at the lower end of the rotating shaft. A protective cover is provided on the upper part of the stirring assembly.

[0007] Furthermore, the outer sides of the first, second, and third absorption towers include a water supply system and a transmission system, wherein the water supply system is connected to a spray system.

[0008] Furthermore, the transmission system includes a motor and a drive shaft, on which a bevel gear is provided. The transmission system drives the stirring assembly to stir the packing material through the bevel gear.

[0009] Furthermore, the throat of the Venturi nozzle is provided with a through hole that connects to the exhaust gas inside the tower.

[0010] Furthermore, the spray pipes and spray nozzles are detachably connected.

[0011] Furthermore, the Venturi nozzle has a first annular protrusion and a second annular protrusion at its tail end, and an annular groove is provided between the first annular protrusion and the second annular protrusion.

[0012] Furthermore, the spray pipe has grooves that correspond to the two annular protrusions of the Venturi tube spray nozzle. The Venturi tube spray nozzle is detachably connected to the grooves of the spray pipe by engaging the first annular protrusion and the second annular protrusion.

[0013] Furthermore, the spray pipes can be in a straight line or a cross shape.

[0014] Furthermore, the outer sides of the first absorption tower, the second absorption tower, and the third absorption tower are each provided with two working windows with openable structures, which are located in the first packing area and the second packing area, respectively.

[0015] The above-mentioned technical solutions in the staged absorption tower group for absorbing NMP tail gas provided in this embodiment of the utility model have at least one of the following technical effects: The stirring assembly prevents NMP polymer adhesion and deposition, effectively alleviating packing blockage; the spray system optimizes the dispersion of the spray liquid by using Venturi nozzles, enhancing gas-liquid contact and improving initial absorption efficiency; the three-stage absorption tower connection structure enhances absorption efficiency. The Venturi nozzles enhance atomization, and the stirring assembly reduces polymer adhesion in the packing area, resulting in improved operator efficiency, reduced maintenance downtime, and less packing blockage. Attached Figure Description

[0016] To more clearly illustrate the technical solutions in the embodiments of this utility model, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this utility model. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0017] Figure 1This is a three-dimensional structural diagram of a staged absorption tower assembly for absorbing NMP tail gas, provided as an embodiment of the present invention.

[0018] Figure 2 for Figure 1 The partial structure is shown in the figure.

[0019] Figure 3 for Figure 2 A sectional view.

[0020] Figure 4 A schematic diagram of the Venturi tube spray nozzle provided for an embodiment of this utility model is shown in the figure.

[0021] Figure 5 The cross-sectional view of the Venturi tube spray nozzle provided for the embodiment of this utility model is shown in the figure.

[0022] The following are the labeling elements in the figure: 100 Absorption Tower Group, 110 First Absorption Tower, 120 Second Absorption Tower, 130 Third Absorption Tower, 140 Fan, 150 Exhaust Pipe, 160 Ventilation Duct, 170 Absorption Liquid Tower, 180 Waste Liquid Tank; 200 Spray system, 210 Spray pipe, 220 Spray nozzle, 231 Contraction section, 232 Throat, 233 Expansion section, 234 First annular protrusion, 235 Second annular protrusion, 236 Through hole; 310 First packing zone, 320 Second packing zone, 321 Packing support grid, 322 Packing, 323 Packing pressure plate; 330 Stirring assembly, 331 Three straight blades, 340 Protective cover, 350 Waste liquid zone; 410 Working window, 420 Liquid storage tank, 430 Water pump, 440 Transmission system. Detailed Implementation

[0023] The embodiments of the present invention are described in detail below, examples of which are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and intended to explain the embodiments of the present invention, and should not be construed as limiting the present invention.

[0024] In the description of the embodiments of this utility model, it should be understood that the terms "length", "width", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings. They are only for the convenience of describing the embodiments of this utility model and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this utility model.

[0025] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of embodiments of this utility model, "a plurality of" means two or more, unless otherwise explicitly specified.

[0026] In this embodiment of the invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; 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; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this embodiment of the invention according to the specific circumstances.

[0027] In one embodiment of this utility model, such as Figure 1 As shown, a staged absorption tower group 100 for absorbing NMP exhaust gas is provided, including a first absorption tower 110, a second absorption tower 120, and a third absorption tower 130. A fan 140 is connected to the left side of the first absorption tower 110. The fan 140 transports the NMP exhaust gas to the first absorption tower 110 through an exhaust pipe 150. The first absorption tower 110, the second absorption tower 120, and the third absorption tower 130 are connected by a ventilation duct 160. After the NMP exhaust gas undergoes its first recovery in the first absorption tower 110, it passes sequentially through the second absorption tower 120 and the third absorption tower 130 through the ventilation duct 160. The NMP exhaust gas is discharged from the third absorption tower 130, achieving staged treatment of NMP exhaust gas from high to medium to low concentrations, resulting in better purification of the NMP exhaust gas and reducing pollution to the outside world.

[0028] Specifically, such as Figure 2-3 As shown, the first absorption tower 110, the second absorption tower 120, and the third absorption tower 130 are equipped with a water supply system on their outer sides and a spray system 200 on their inner sides. Specifically, the water supply system includes a water pump 430 and a storage tank 420 for storing the absorbent liquid, with the water pump 430 located on top of the storage tank 420. When the water pump 430 is started, it transports the absorbent liquid in the storage tank 420 to the spray system 200. Specifically, an absorbent liquid tower 170 is also provided at the staged absorption tower group 100 to replenish the absorbent liquid in the storage tank 420.

[0029] Specifically, such as Figure 3As shown, the first absorption tower 110, the second absorption tower 120, and the third absorption tower 130 are equipped with two packing zones inside, which are named the first packing zone 310 and the second packing zone 320 from top to bottom. Specifically, both the first packing zone 310 and the second packing zone 320 are equipped with a spray system 200 at their upper parts, which includes a spray pipe 210 and spray nozzles 220. Specifically, the first packing zone 310 and the second packing zone 320 include a packing support grid 321, packing material 322, and a packing pressure plate 323. The interior of the tower body is divided into spaces by welded partitions or support frames for fixing the packing support grid 321 and the packing pressure plate 323. The packing material 322 is placed within the space formed by the packing support grid 321 and the packing pressure plate 323.

[0030] like Figure 1-3 As shown, NMP exhaust gas flows sequentially through the first absorption tower 110, the second absorption tower 120, and the third absorption tower 130 under the action of the fan 140. The NMP exhaust gas first enters the second packing zone 320. Under the guiding effect of the packing support grid 321 in the second packing zone 320, the NMP exhaust gas forms a radial diffusion and uniformly enters the packing 322 in the second packing zone 320. After the spray nozzle 220 at the top of the second packing zone 320 fully atomizes and sprays out the absorbent liquid, the atomized droplets immediately contact the packing 322, forming a liquid film covering layer at the top of the second packing zone 320. The liquid film flows downward along the surface of the packing 322 and enters the porous channels of the packing 322. The porous channels of the packing 322 adsorb the absorbent liquid, and a stable liquid film is formed on the surface of the packing 322, enhancing the gas-liquid mass transfer efficiency of the NMP exhaust gas and the absorbent liquid in the packing 322. New absorbent is replenished from nozzle 220. The NMP-absorbed waste liquid flows down the surface of packing 322, while the unabsorbed tail gas continues to flow upward. The two come into counter-current contact in the porous channels of packing 322, forming a continuous mass transfer gradient to ensure that NMP molecules continuously transfer from the gas phase to the liquid phase. The NMP-absorbed waste liquid enters the waste liquid zone 350 at the bottom of the absorption tower, and is finally discharged from the waste liquid zone 350 and stored in the waste liquid tank 180. The NMP tail gas, after preliminary absorption, enters the first packing zone 310. The NMP concentration in the tail gas has been significantly reduced, and the airflow velocity is reduced. At this point, a more preferred approach is to use smaller-sized packing 322 in the first packing zone 310 to form denser channels and reduce droplet entrainment. The reduced flow rate of absorbent from nozzle 220 forms a thinner liquid film on the surface of packing 322, shortening the diffusion distance of NMP molecules and improving mass transfer efficiency. At this time, the absorption in the first packing zone 310 mainly relies on molecular diffusion driven by concentration difference: the NMP concentration on the surface of the liquid film is close to the equilibrium value, while the concentration inside the liquid film is kept low due to the replenishment of fresh absorbent, forming a concentration gradient from the gas-liquid interface to the inside of the liquid film, which forces the residual NMP molecules to continue to diffuse into the liquid phase.

[0031] Specifically, the spray pipe 210 can be in a straight line, or alternatively, in a cross shape. The absorbent liquid, pressurized by the water supply system, enters the spray system 200, forming a continuous and stable spray flow covering the surface of the packing zone. Under normal cleaning requirements, the straight-line spray pipe 210 uses linearly arranged nozzles to spray the packing layer 322 longitudinally, achieving uniform coverage and meeting basic cleaning requirements. In complex conditions with polymer adhesion, the cross-shaped spray pipe 210 uses intersecting nozzles to form a multi-directional spray surface, performing a grid-like flushing of the packing zone surface, enhancing the impact range on viscous deposits. The combination of the first packing zone 310, the second packing zone 320, and the corresponding spray system 200 achieves intra-tower staged absorption of "large-scale absorption in the second packing zone 320 + deep absorption in the first packing zone 310," combined with inter-tower staged absorption of the first absorption tower 110, the second absorption tower 120, and the third absorption tower 130 connected in series, forming a dual-stage treatment system of "intra-tower + inter-tower."

[0032] Another embodiment of this utility model, such as Figure 4-5 As shown, the spray nozzle 220 of the first absorption tower 110 is a Venturi tube spray nozzle 220 with a contraction section 231, a throat 232, and an expansion section 233. Preferably, the throat 232 of the Venturi tube spray nozzle 220 is provided with a through hole 236 communicating with the tail gas inside the absorption tower. When the absorbent flows through the contraction section 231-throat 232-expansion section 233, the flow velocity in the throat 232 increases sharply and the pressure drops sharply, forming a negative pressure. The negative pressure adsorbs the undissolved gas (mainly air and unabsorbed NMP gas) accumulated in the tower through the through hole 236, causing the gas and absorbent to mix violently in the throat 232. The high-speed fluid breaks up the gas to form microbubbles, increasing the gas-liquid contact area, while reducing the amount of NMP gas in the tower and inhibiting NMP polymerization. As another preferred embodiment, the Venturi tube spray nozzle 220 can be set only in the upper part of the second packing zone 320 of the first absorption tower 110 to precisely inhibit the area where NMP is prone to polymerization and optimize cost input. The improved gas-liquid mixing efficiency brought by the Venturi spray nozzle 220 shortens the residence time of undissolved NMP exhaust gas, extends the cleaning and maintenance cycle, ensures the continuity of the production process, and reduces the intensity of manual operation.

[0033] Another embodiment of this utility model, such as Figure 3-5As shown, the second packing zone 320 of the first absorption tower 110 is equipped with a stirring assembly 330 for agitating the packing 322. The stirring assembly 330 includes three straight blades 331 and a rotating shaft, with the three straight blades 331 located at the lower end of the rotating shaft. A transmission system 440 for driving the stirring assembly 330 is provided on the outer side of the tower body of the first absorption tower 110. The transmission system 440 includes a motor and a drive shaft, and drives the stirring assembly 330 to agitate the packing 322 via a bevel gear. When the motor starts, the drive shaft drives the driving bevel gear to rotate, which in turn drives the driven bevel gear and the rotating shaft to rotate vertically axially through tooth meshing, causing the three straight blades 331 to create disturbance within the packing 322 layer. By periodically agitating the packing 322 layer, the formation of a dense adhesion layer of NMP polymer within the pores of the packing 322 can be reduced, thus lowering the cleaning frequency. Preferably, a protective cover 340 is provided on the upper part of the stirring assembly 330. The protective cover 340 semi-encloses the transmission part of the stirring assembly 330. The top of the protective cover 340 is designed with an arc or sloping structure to guide the liquid flow to both sides. When the spray system 200 is working, the liquid is atomized by the Venturi nozzle 220 and sprayed downwards. The protective cover 340 physically isolates the liquid so that it flows along the outer wall of the cover to the packing layer 322, avoiding direct impact on the connection between the rotating shaft and the bevel gear. At the same time, polymer debris or detached packing particles generated by high temperature in the packing area are blocked by the side wall of the protective cover 340 when they fall under gravity, preventing them from entering the transmission system 440. Thus, the connection between the drive shaft and the motor always operates in a relatively clean environment.

[0034] In another embodiment of this utility model, the spray pipe 210 and the spray nozzle 220 are detachably connected. Detachable connection means that the spray pipe 210 and the spray nozzle 220 form a separable mechanical connection, which can be achieved by snap-fit, threaded connection, or flange connection, allowing for quick assembly and disassembly through a pre-designed mating structure. Preferably, the Venturi nozzle 220 has a first annular protrusion 234 and a second annular protrusion 235 at its tail, with an annular groove between the first annular protrusion 234 and the second annular protrusion 235. The spray pipe 210 has grooves that correspond to the first annular protrusion 234 and the second annular protrusion 235 of the Venturi nozzle 220, and the Venturi nozzle 220 is detachably connected by snapping the first annular protrusion 234 and the second annular protrusion 235 into the groove of the spray pipe 210. During the operation of the spray system 200, the Venturi nozzle 220 is assembled by embedding its tail-end first annular protrusion 234 and second annular protrusion 235 into the corresponding groove of the spray pipe 210. The annular groove refers to the axial gap between the first annular protrusion 234 and the second annular protrusion 235, which can be adjusted by changing the distance between the first annular protrusion 234 and the second annular protrusion 235 to provide elastic deformation space to adapt to the assembly requirements of the groove of the spray pipe 210. When the nozzle 220 needs to be cleaned, the operator can directly pull the nozzle 220 out axially without disassembling the entire structure of the spray pipe 210. This connection method ensures airtightness while making the nozzle 220 an independent replaceable module. For nozzles 220 that are clogged due to NMP polymer adhesion, maintenance only requires separating the local parts for cleaning or replacement.

[0035] like Figure 1-5 As shown, the outer sides of the first absorption tower 110, the second absorption tower 120, and the third absorption tower 130 are each equipped with two operable working windows 410, located in the first packing zone 310 and the second packing zone 320, respectively. These windows can be implemented using hinged sealing doors or sliding covers, and can open to the side or upwards. The positions of the working windows 410 correspond to the first packing zone 310 and the second packing zone 320, allowing direct contact with the surface of the packing layer 322 after opening, forming a physical maintenance channel. When it is necessary to clean the NMP polymer adhering to the surface of the packing layer 322, operators do not need to disassemble the tower or move the packing 322; they can directly open the corresponding working window 410 for manual cleaning or mechanical scraping. When it is necessary to clean the packing 322, operators can move the packing 322 through the working window 410. The sealing structure of the working window 410 maintains the airtightness of the tower when closed, preventing exhaust gas leakage.

[0036] Through the above technical solution, this application achieves the following through a graded absorption structure and graded absorption towers: the NMP concentration in the first absorption tower 110 decreases from ≥80% to 20%-40% in the second absorption tower 120 and then to ≤5% in the third absorption tower 130. It also reduces the intensity of manual cleaning of the packing 322, and has the advantages of improving processing efficiency, reducing maintenance downtime, and reducing clogging of the packing 322 and the spray nozzles 220.

[0037] The above description is only a preferred embodiment of the present utility model and is not intended to limit the present utility model. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present utility model should be included within the protection scope of the present utility model.

Claims

1. A staged absorption tower assembly for absorbing NMP tail gas, characterized in that: The absorption system includes a first absorption tower, a second absorption tower, and a third absorption tower. Each of the three absorption towers is equipped with a spray system and two packing zones, which are arranged from top to bottom as the first packing zone and the second packing zone. The spray system includes spray pipes and spray nozzles. Spray systems are installed at the top of both the first and second packing zones. The spray nozzles of the first absorption tower are Venturi tube nozzles with a contraction section, a throat, and an expansion section. The first and second packing zones include packing support grids, packing, and packing pressure plates. The second packing zone of the first absorption tower is equipped with a stirring assembly for agitating the packing.

2. The staged absorption tower assembly for absorbing NMP tail gas according to claim 1, characterized in that: The packing plate of the second packing zone is equipped with a stirring assembly, which includes three straight blades and a rotating shaft. The upper end of the rotating shaft is equipped with a bevel gear, and the three straight blades are located at the lower end of the rotating shaft. A protective cover is provided on the upper part of the stirring assembly.

3. The staged absorption tower assembly for absorbing NMP tail gas according to claim 1, characterized in that: The outer sides of the first, second, and third absorption towers include a water supply system and a transmission system, and the water supply system is connected to a spray system.

4. The staged absorption tower assembly for absorbing NMP tail gas according to claim 3, characterized in that: The transmission system includes a motor and a drive shaft. A bevel gear is provided on the drive shaft. The transmission system drives the stirring assembly to stir the filler through the bevel gear.

5. A staged absorption tower assembly for absorbing NMP tail gas according to claim 1, characterized in that: The throat of the Venturi nozzle is provided with a through hole that communicates with the exhaust gas inside the tower.

6. A staged absorption tower assembly for absorbing NMP tail gas according to claim 1, characterized in that: The spray pipes and spray nozzles are detachably connected.

7. A staged absorption tower assembly for absorbing NMP tail gas according to claim 6, characterized in that: The Venturi nozzle has a first annular protrusion and a second annular protrusion at its tail end, and an annular groove is provided between the first annular protrusion and the second annular protrusion.

8. A staged absorption tower assembly for absorbing NMP tail gas according to claim 6, characterized in that: The spray pipe has grooves that correspond to the two annular protrusions of the Venturi tube spray nozzle. The Venturi tube spray nozzle is detachably connected to the grooves of the spray pipe by the first annular protrusion and the second annular protrusion engaging with each other.

9. A staged absorption tower assembly for absorbing NMP tail gas according to claim 1, characterized in that: The spray pipe can be in a straight line or a cross shape.

10. A staged absorption tower assembly for absorbing NMP tail gas according to claim 1, characterized in that: The first absorption tower, the second absorption tower, and the third absorption tower are each provided with two openable working windows on the outer side of the tower body. The working windows are located in the first packing area and the second packing area, respectively.

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