Formaldehyde absorption tower and absorption method thereof

Abstract

The invention provides a formaldehyde absorption tower and an absorption method thereof, the absorption tower comprises an absorption tower body, a plurality of layers of tower trays I are arranged in a tower kettle of the absorption tower body, and a broken tower tray I, a filler layer I, a liquid distributor I, a broken tower tray II, a filler layer II, a liquid distributor II and a tower tray II are sequentially arranged at the upper part of the tower tray I; the tower internals formed by combining the trays and the filler are adopted, and each tray adapts to the working condition of the corresponding position, so that the efficiency of the tower internals is improved, and the tower height is reduced; the absorption tower can be transformed on the basis of an original absorption tower for producing formaldehyde through a silver method, the tower height does not need to be increased, only internal parts are transformed, and transformation investment is saved; the mode of combining the tower tray and the filler ensures that internal parts of the absorption tower are not blocked under the condition that the formaldehyde concentration is more than 50%, and long-period stable operation of the absorption tower is ensured.

Description

Technical Field

[0001] The present application relates to the technical field of chemical equipment, and in particular to a formaldehyde absorption tower and an absorption method thereof. Background Art

[0002] Formaldehyde preparation adopts the tail gas circulation silver production process. Generally, the formaldehyde absorption tower adopts two-stage absorption plus N-layer tower plate absorption, and the crude formaldehyde product concentration is designed to be about 50%; the crude formaldehyde product concentration is controlled by the amount of desalted water used at the top of the formaldehyde absorption tower. If you want to get a higher concentration of crude formaldehyde, you need to reduce the amount of desalted water used. Reducing the amount of desalted water will easily cause high-concentration formaldehyde to crystallize and self-aggregate to form particles that block the tower internals and the bottom circulating plate heat exchanger at the bottom of the tower. The blockage will cause the heat exchange effect of the heat exchanger to decrease, and will also cause the absorption effect of the lower internals of the absorption tower to decrease, which is not conducive to long-term stable production.

[0003] For example, a formaldehyde absorption tower with application number 200910179967X discloses a technical solution. The absorption tower includes a kettle, a mixed gas inlet and a finished formaldehyde outlet are arranged at the lower part of the kettle, a water inlet and an exhaust gas outlet are arranged at the upper part of the kettle, two layers of fillers are arranged in the kettle, and a formaldehyde solution circulation pipeline is arranged between each layer of fillers. During the replacement process of the mixed gas from bottom to top and the water from top to bottom, the formaldehyde in the mixed gas dissolves into the water to form formaldehyde liquid, and the formaldehyde liquid circulates in the two layers of fillers to gradually increase the concentration of formaldehyde. This patent application solves the absorption efficiency and the phenomenon of preventing formaldehyde polymerization in the production of medium and high concentration formaldehyde solutions by designing segmented fillers and special circulating spraying devices.

[0004] Although the above patent adopts a special circulating spray device design, in this application, the mixed gas in the tower kettle still passes directly from bottom to top through the first packing layer and the second packing layer, which is prone to blockage of the packing layer and the circulating plate heat exchanger, thereby causing the absorption effect of the absorption tower to decrease; therefore, it is necessary to provide a new technical solution to solve the above technical problems. Summary of the invention

[0005] The present application provides a formaldehyde absorption tower, comprising an absorption tower body, wherein a desalted water feed pipeline and an exhaust pipeline are arranged on the upper part of the absorption tower body; a feed pipeline is connected to the lower part of the absorption tower body, a formaldehyde extraction pipeline is connected to the tower kettle of the absorption tower body, a multi-layer tower plate 1 is arranged inside the tower kettle of the absorption tower body, a broken tower plate 1, a packing layer 1, a liquid distributor 1, a broken tower plate 2, a packing layer 2, a liquid distributor 2, and a tower plate 2 are arranged in sequence on the upper part of the tower plate 1, and a liquid outlet is arranged between the bottom of the broken tower plate 1 and the packing layer 1. Inlet 1 is provided between the upper part of the liquid distributor 1 and the lower part of the breaking tower plate 2 at a position corresponding to the absorption tower body, a circulation pipeline 1 is provided between the liquid outlet 1 and the liquid inlet 1, a cooler 1 is provided on the circulation pipeline 1, a liquid outlet 2 is provided between the breaking tower plate 2 and the lower part of the packing layer 2, a liquid inlet 2 is provided between the upper part of the liquid distributor 2 and the tower plate 2 at a position corresponding to the absorption tower body, a circulation pipeline 2 is provided between the liquid outlet 2 and the liquid inlet 2, and a cooler 2 is provided on the circulation pipeline 2.

[0006] As a preferred solution, the tower tray 1 adopts 5-10 layers of anti-blocking tower trays.

[0007] As a preferred solution, the tower tray 2 uses 12-20 layers of anti-blocking tower trays.

[0008] As a preferred solution, the formaldehyde extraction pipeline is connected to a tower bottom circulation pipeline, and the tower bottom circulation pipeline is connected to the absorption tower body corresponding to the upper part of the uppermost tower tray one.

[0009] As a preferred solution, a feed cooler is provided on the feed pipeline.

[0010] As a preferred solution, a steam generator is provided in front of the feed cooler.

[0011] As a preferred embodiment, the anti-blocking tower plate includes a tower plate body, a plurality of injection nozzles are arranged on the tower plate body, a cap is installed on the tower plate body corresponding to the injection nozzle, the cap includes a cap body, the length and width of the injection nozzle are smaller than the length and width of the cap projected on the tower plate body, a cap top plate is arranged on the top of the cap body, a top gap is provided between the cap top plate and the cap body, the cap body includes two symmetrically arranged cap plates, two side plates are symmetrically arranged between the two cap plates, a plurality of spoiler holes are opened on the two side plates, and an inner spoiler plate or an outer spoiler plate is arranged on the side plate above the spoiler hole.

[0012] As a preferred solution, inner spoiler plates and outer spoiler plates are alternately arranged on spoiler holes that are adjacent in a horizontal row.

[0013] As a preferred solution, the cap body is installed on the tower plate, and the angle between the side plate and the vertical plane of the tower plate is 3°-6°.

[0014] As a preferred solution, the angle between the side plate and the vertical plane of the tower plate is 4.5°.

[0015] As a preferred solution, the shape of the spoiler hole is the same as the shape of the inner spoiler plate and the shape of the outer spoiler plate.

[0016] As a preferred solution, the spoiler hole has a shape of at least one of an elliptical shape, a square shape, and a racetrack shape.

[0017] As a preferred solution, the inner spoiler, the outer spoiler and the side panel are integrally formed.

[0018] As a preferred solution, the inner spoiler plate is formed by punching the spoiler hole inwards, and the outer spoiler plate is formed by punching the spoiler hole outwards.

[0019] As a preferred solution, the injection nozzle includes a rectangular hole, the length and width of the rectangular hole are smaller than the length and width of the projection of the cap cover on the tower plate body, and an inclined injection plate is installed at the edge of the rectangular hole, and the angle between the injection plate and the vertical plane of the tower plate body is 3°-6°.

[0020] A formaldehyde absorption method comprises the following steps:

[0021] S1: Desalted water is introduced into the top of the absorption tower body, and the desalted water flows into the tower kettle of the absorption tower body from the top of the absorption tower body;

[0022] S2: The formaldehyde raw material is introduced into the bottom of the absorption tower through the feed pipeline;

[0023] S3: The gas phase passes through the multiple layers of trays one in turn and enters the desalted water layer of the upper tray one. The gas and liquid phases are fully in contact, and the formaldehyde in the gas phase dissolves into the liquid phase, achieving formaldehyde absorption;

[0024] S4: When the gas phase treated by the multi-layer trays rises to the breaking tray, the gas phase enters the packing layer above the breaking tray, and the liquid falling from the packing layer is intercepted on the breaking tray. The liquid on the breaking tray is cooled and then circulated into the packing layer. The liquid level on the breaking tray exceeds the gas phase rising pipe and overflows to the top of the tray below the breaking tray.

[0025] S5: When the gas phase rises to the break tray 2 through the packing layer 1, the gas phase enters the packing layer 2 above the break tray 2, and the liquid falling from the packing layer 2 is intercepted on the break tray 2. The liquid phase on the break tray 2 is cooled and then circulated into the packing layer 2. The liquid level on the break tray 2 exceeds the gas phase riser and overflows to the liquid distributor 1 at the bottom of the break tray 2.

[0026] S6: The gas phase passing through the packing layer 2 sequentially passes through the multi-layer tower tray 2 to enter the desalted water liquid layer of the upper tower tray 2, and the desalted water absorbs formaldehyde in the gas phase. The gas phase after absorbing formaldehyde is discharged through the exhaust pipeline, and the liquid phase passes through the packing layer 2, the broken tower tray 2, the packing layer 1, and the broken tower tray 1 to enter the top of the tower tray 1 of the tower kettle of the absorption tower body;

[0027] S7: The kettle of the absorption tower body generates formaldehyde product, a part of which is extracted from the kettle of the absorption tower body, and a part of which is circulated into the upper part of the uppermost tray in the absorption tower body to circulate and absorb formaldehyde.

[0028] This application has the following advantages:

[0029] (1) The tower internals are in the form of a combination of trays and packings. Each tray is adapted to the working conditions of its own position, so that the efficiency of the tower internals is improved and the tower height is reduced;

[0030] (2) The existing absorption tower for producing formaldehyde by the silver process can be modified without increasing the tower height. Only the internal parts need to be modified, thus saving modification investment.

[0031] (3) The combination of tray 1, tray 2 and filler ensures that the tower internals will not be blocked when the formaldehyde concentration is above 50%, ensuring the long-term stable operation of the absorption tower;

[0032] (4) The formaldehyde concentration inside the tower is distributed in a gradient, and the temperature is also distributed in a gradient, which controls the possibility of crystallization blockage of formaldehyde under high concentration conditions. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 It is a schematic diagram of the structure of this application;

[0034] Figure 2 This is a structural schematic diagram of the anti-clogging tray of the present application from an angle 1;

[0035] Figure 3 This is a structural schematic diagram of the anti-clogging tray of the present application from an angle 2;

[0036] Figure 4 This is a structural schematic diagram of a partial angle 1 of the present application;

[0037] Figure 5 It is a structural schematic diagram of part 2 of the present application;

[0038] Figure 6 It is a structural schematic diagram of the side panel angle 1 of the present application;

[0039] Figure 7 It is a structural schematic diagram of the side panel angle 2 of the present application;

[0040] Figure 8It is a schematic diagram of the temperature distribution in the absorption tower in the prior art;

[0041] Fig. 9 It is a schematic diagram of the formaldehyde concentration distribution in the absorption tower in the prior art;

[0042] Fig.10 It is a schematic diagram of the temperature distribution in the absorption tower of the present application;

[0043] Fig.11 It is a schematic diagram of the formaldehyde concentration distribution in the absorption tower of the present application;

[0044] 1. Absorption tower body; 2. Desalted water feed pipeline; 3. Exhaust pipeline; 4. Feed pipeline; 5. Feed cooler; 6. Steam generator; 7. Formaldehyde extraction pipeline; 8. Tower kettle circulation pipeline; 9. Formaldehyde extraction pump; 10. Tower tray 1; 11. Packing layer 1; 12. Packing layer 2; 13. Break tower tray 1; 14. Break tower tray 2; 15. Tower tray 2; 16. Liquid outlet 1; 17. Liquid inlet 1; 18. Circulation pipeline 1; 19. Cooler 1; 20. Circulation Circular pump one; 21. Liquid outlet two; 22. Liquid inlet two; 23. Circulation pipeline two; 24. Cooler two; 25. Circulation pump two; 26. Liquid distributor one; 27. Liquid distributor two; 28. Tower plate; 29. ​​Injection nozzle; 30. Injection plate; 31. Cap cover body; 32. Cap cover plate; 33. Side plate; 34. Cap cover top plate; 35. Top gap; 36. Spoiler hole; 37. Inner spoiler; 38. Outer spoiler; 39. Lower gap. DETAILED DESCRIPTION

[0045] The following is combined with Figures 1 to 11 The specific implementation of the present invention is described in detail. It should be noted that the specific implementation described here is only used to illustrate and explain the present invention, and is not used to limit the present invention.

[0046] Embodiment 1:

[0047] like Figure 1As shown, the present application provides a formaldehyde absorption tower, including an absorption tower body 1, a desalted water feed pipeline 2 and an exhaust pipeline 3 are arranged on the upper part of the absorption tower body 1, the desalted water feed pipeline 2 is used to pass desalted water, and the desalted water flows from the top of the absorption tower body 1 to the bottom of the absorption tower body 1, and the lower part of the absorption tower body 1 is connected to a feed pipeline 4, and the feed pipeline 4 is used to pass a gas mixture of formaldehyde gas, air (nitrogen, oxygen, rare gas, carbon dioxide, water vapor, dust, sulfur dioxide, nitrogen oxides and other gases and impurities) and other components. Preferably, a feed cooler 5 is arranged on the feed pipeline 4. Because high temperature is not conducive to formaldehyde absorption, the feed cooler 5 is arranged to feed the original The feed gas is cooled to remove part of the heat of the feed gas; a steam generator 6 is arranged in front of the feed cooler 5 to produce part of the low-pressure steam by utilizing the heat of the feed, so as to improve the utilization efficiency of the heat; the kettle of the absorption tower body 1 is connected with a formaldehyde extraction pipeline 7, and a formaldehyde extraction pump 9 is arranged on the formaldehyde extraction pipeline 7, and a kettle circulation pipeline 8 is connected to the formaldehyde extraction pipeline 7, and the kettle circulation pipeline 8 is connected to the lower part of the absorption tower body 1; a multi-layer tower tray 10 is arranged inside the kettle of the absorption tower body 1, and preferably, the tower tray 10 adopts 5-10 layers of anti-blocking tower trays, and a multi-layer tower tray 10 is arranged in the kettle as a circulation section, and the formaldehyde product in the circulation section is partially extracted. Part of it is injected into the absorption tower body 1 to continue to circulate and absorb formaldehyde; the formaldehyde concentration in the tower bottom is very high, reaching 50%, and it is easy to self-polymerize. In this section of cyclic absorption, no cooler is set, only cyclic absorption is carried out without cooling, so as to reduce the occurrence of self-polymerization and thus reduce the possibility of blockage; and the setting of the anti-blocking tower tray can further prevent the crystallization due to self-polymerization; the upper part of the tower tray 10 is sequentially provided with a broken tower tray 13, a packing layer 11, a liquid distributor 26, a broken tower tray 2 14, a packing layer 2 12, a liquid distributor 27, and a tower tray 2 15. Preferably, the tower tray 2 15 adopts 12-20 layers of anti-blocking tower trays. The setting of the tower tray 2 15 can increase the mass transfer efficiency, and also for the purpose of Under the condition of a small amount of desalted water, the tower washing effect is ensured, so that the formaldehyde content of the gas out of the tower is reduced to the control value; a liquid outlet 16 is arranged between the broken tower plate 13 and the bottom of the packing layer 11, a liquid inlet 17 is arranged between the upper part of the liquid distributor 26 and the lower part of the broken tower plate 14 at a position corresponding to the absorption tower body 1, a circulation pipeline 18 is arranged between the liquid outlet 16 and the liquid inlet 17, a cooler 19 and a circulation pump 20 are arranged on the circulation pipeline 18, a liquid outlet 21 is arranged between the broken tower plate 14 and the lower part of the packing layer 12, and a liquid inlet 22 is arranged between the upper part of the liquid distributor 27 and the tower plate 15 at a position corresponding to the absorption tower body 1;A liquid inlet 22 is provided between the upper part of the packing layer 12 and the tower plate 15. More specifically, the liquid inlet 22 is connected to the liquid distributor 26. A circulation pipeline 23 is provided between the liquid outlet 21 and the liquid inlet 22. A cooler 24 and a circulation pump 25 are provided on the circulation pipeline 23. Through the high-efficiency and high-throughput packing layer 11 and the packing layer 12, and the broken tower plate 13 and the broken tower plate 14 corresponding to the packing layer 11, the formaldehyde concentration is controlled by absorbing formaldehyde through liquid circulation. Because the formaldehyde absorption process is an exothermic reaction, the raw gas has a certain temperature, so that the whole raw gas has a certain amount of heat. The whole absorption in the tower bottom will release a large amount of absorption heat, and all this heat needs to be removed by heat exchange. In this embodiment, the heat is removed by the setting of the cooler 19 and the cooler 24 to avoid self-aggregation to form crystalline particles when the temperature changes, which causes blockage. The occurrence of the phenomenon; both the broken tower plate 13 and the broken tower plate 2 14 are provided with a gas phase riser, and a liquid baffle is provided on the upper part of the gas phase riser to prevent the liquid from the upper filler from directly entering the gas phase riser. The gas phase rises through the annular gap between the upper edge of the riser and the upper liquid baffle. After the liquid level on the corresponding broken tower plate exceeds the gas phase riser, it can overflow downward to the lower layer of the corresponding broken tower plate; specifically, after the liquid level on the broken tower plate 1 exceeds the gas phase riser, it overflows to the tower kettle of the absorption tower body 1 at the lower part of the broken tower plate; after the liquid level on the broken tower plate 2 14 exceeds the gas phase riser, it overflows to the filler layer 11 at the lower part of the broken tower plate 2 14; the structure of the broken tower plate belongs to mature technology, and this application does not make any improvement to it, and will not be described in detail here; in this embodiment, it can ensure that the concentration index at the bottom of the tower meets the process requirements, and ensure that the bottom of the tower will not be blocked, and it can operate stably for a long period of time, thereby reducing the steam usage of the formaldehyde absorption system, reducing the steam usage, and achieving the purpose of energy saving and consumption reduction. ;

[0048] The gas mixture enters the kettle of the absorption tower body 1 through the feed pipeline 4, and the desalted water used to absorb the formaldehyde gas flows into the kettle of the absorption tower body 1 from the top of the absorption tower body 1, and the gas phase in the kettle passes through the multi-layer tower plate 10 from bottom to top and enters the desalted water liquid layer of the upper tower plate 10, and the gas and liquid phases are fully in contact, and the formaldehyde in the gas phase will dissolve in the desalted water liquid phase to achieve formaldehyde absorption. When the gas phase treated by the multi-layer tower plate 10 rises to the breaking tower plate 13, the gas phase enters the packing layer 11 above the breaking tower plate 13, and the liquid falling from the packing layer 11 is intercepted on the breaking tower plate 13. After cooling, the liquid phase on the breaking tower plate 13 circulates into the packing layer 11. After the liquid level on the breaking tower plate 13 exceeds the gas phase rising pipe, it overflows to the top of the tower plate 10 below the breaking tower plate 13; when the gas phase passes through the packing layer 11 and rises to the breaking tower plate 2 14, the gas phase enters the packing layer 2 12 above the breaking tower plate 2 14 The liquid dropped from the packing layer 12 is intercepted on the broken tower plate 14, and the liquid phase on the broken tower plate 14 is circulated into the packing layer 12 after being cooled. After the liquid level on the broken tower plate 14 exceeds the gas phase riser, it overflows to the liquid distributor 26 at the bottom of the broken tower plate 14; the gas phase passing through the packing layer 12 successively passes through the multi-layer tower plate 15 to enter the desalted water liquid layer of the upper tower plate 15, and the desalted water absorbs formaldehyde in the gas phase. The gas phase after absorbing formaldehyde is discharged through the exhaust pipeline 3 and enters the subsequent treatment process. The liquid phase passes through the packing layer 12, the broken tower plate 14, the packing layer 14, and the broken tower plate 13 again to the upper part of the tower plate 10 of the tower kettle of the absorption tower body 1; the tower kettle of the absorption tower body 1 generates formaldehyde product, a part of the generated formaldehyde product is extracted from the tower kettle of the absorption tower body 1, and a part is circulated into the upper part of the uppermost tower plate 10 in the absorption tower body 1 to circulate and absorb formaldehyde.

[0049] In this embodiment, the tower tray 10, the packing layer 11, the packing layer 2 12, and the tower tray 2 15 can all play a role in absorbing formaldehyde, thereby obtaining a formaldehyde product with a higher concentration.

[0050] Embodiment 2:

[0051] This embodiment describes the anti-blocking tray, specifically:

[0052] like Figures 2 to 7As shown, the anti-clogging tray includes a circular tray body 28, and a plurality of injection nozzles 29 are arranged on the tray body 28 (only a part of the tray body 28 of this embodiment is intercepted for display). Preferably, the injection nozzle 29 includes a rectangular hole, and an inclined injection plate 30 is installed at the edge of the rectangular hole to form a reduced diameter. The angle between the injection plate 30 and the vertical plane of the tray body 28 is 3°-6°, and more preferably 4.5°; the reduced diameter injection nozzle 29 can increase the injection force when the gas passes through, enhance the ability of the gas to drive the liquid, increase the rate of liquid circulation, prevent the precipitation and agglomeration of particulate matter, and play an anti-clogging role; a cap is installed on the tray body 28 corresponding to the injection nozzle 29, and the cap includes a cap body 31. The length and width of the injection nozzle 29 are less than the length and width of the projection of the cap on the tray body 28. The shape of the cap body 31 is not specifically limited, and the technician can make a corresponding selection according to the specific situation. The cap body 31 includes two symmetrically arranged cap plates 32. The cap plates 32 in this embodiment are ladder-shaped. The cap cover body 31 is provided with a cap cover top plate 34 on the top, and there is a top gap 35 between the cap cover top plate 34 and the cap cover body 31. A plurality of spoiler holes 36 are opened on the two side plates 33, and an inner spoiler plate 37 or an outer spoiler plate 38 is provided on the side plates 33 at the upper part of the spoiler holes 36; more specifically, the inner spoiler plate 37 or the outer spoiler plate 38 is provided on the side plates 33. The spoiler 37 or the outer spoiler 38 is a spoiler hole 36 that is folded inward and outward when punching. The inner spoiler 37 folded inward forms a torsion stirring effect, and the outer spoiler 38 folded outward controls the gas-liquid mixture to be sprayed horizontally downward to avoid gas-liquid entrainment. The shape of the spoiler hole 36 is the same as that of the inner spoiler 37 and the outer spoiler 38. In this embodiment, the shape is preferably a runway type; preferably, the inner spoiler 37 and the outer spoiler 38 are staggered on the spoiler holes 36 adjacent to each other in a horizontal row, such as Figure 7 The first horizontal row of spoiler holes shown includes six, the first spoiler hole 36 is provided with an outer spoiler plate 38, the second spoiler hole 36 is provided with an inner spoiler plate 37, the third spoiler hole 36 is provided with an outer spoiler plate 38, the fourth spoiler hole 36 is provided with an inner spoiler plate 37, the fifth spoiler hole 36 is provided with an outer spoiler plate 38, and the sixth spoiler hole 36 is provided with an inner spoiler plate 37, so that a staggered arrangement is achieved, the inner spoiler plate 37 is provided on the inner side of the cap cover body 31, and the outer spoiler plate 38 is provided on the outer side of the cap cover body 31.

[0053] The cap body 31 of this embodiment is installed on the tray body 28 by welding or the like, and a lower gap 39 is provided between the lower part of the cap body 31 and the tray body 28. In actual application, a plurality of cap bodies 31 are evenly installed on the tray body 28, and a cap body 31 is provided at a position corresponding to each injection nozzle 29. In this embodiment, the angle between the side plate 33 and the vertical plane of the tray body 28 is 3°-6°, and more preferably: the angle between the side plate 33 and the vertical plane of the tray body 28 is 4.5°; the setting of the angle of 3°-6° enables the gas-liquid mixture to form a certain downward angle through the outer spoiler 38 under the pressure formed inside the cap body 31, thereby reducing the entrainment of mist.

[0054] The gas enters the cap body 31 through the injection nozzle 29 from the lower part of the tray body 28. The desalted water enters the cap body 31 from the lower gap 39 during the horizontal flow from the upper part of the tray body 28. The gas moves upward with the liquid, and continuously absorbs formaldehyde. The absorbed gas-liquid mixture is ejected through the spoiler holes 36 and the top gap 35 on the side plate 33. The gas-liquid mixture ejected through the spoiler holes 36 flows downward, and under the action of the outer spoiler plate 38, the formaldehyde absorption is further completed. The gas-liquid mixture ejected through the top gap 35 contacts with the cap top plate 34 to complete the absorption of formaldehyde.

[0055] In the present embodiment, during the upward flow of gas and liquid in the cap body 31, the gas-liquid mixture is further mixed by being deflected by the inner spoiler 37, and then passes through the outer spoiler 38 under the pressure formed inside the cap body 31, which is beneficial to the absorption of formaldehyde by the desalted water and reduces the entrainment of mist. Reducing the entrainment of mist can make the formaldehyde in the gas phase contact with the desalted water more fully, making the absorption process more effective.

[0056] Embodiment three:

[0057] This embodiment provides a formaldehyde absorption method, comprising the following steps:

[0058] S1: Desalted water is introduced into the top of the absorption tower body 1; the desalted water flows from the top of the absorption tower body 1 into the tower kettle of the absorption tower body 1;

[0059] S2: The formaldehyde raw material (gas mixture) is introduced into the bottom of the absorption tower body 1 through the feed pipeline 4;

[0060] S3: The gas mixture passes through the multiple layers of trays 10 in sequence and enters the desalted water liquid layer of the upper tray 10. The gas and liquid phases are fully in contact, and the formaldehyde in the gas phase dissolves in the desalted water liquid phase, thereby achieving formaldehyde absorption;

[0061] S4: When the gas phase treated by the multi-layer tray 10 rises to the breaking tray 13, the gas phase enters the packing layer 11 above the breaking tray 13, and the liquid falling from the packing layer 11 is intercepted on the breaking tray 13. The liquid phase on the breaking tray 13 is cooled and circulated into the packing layer 11. After the liquid level on the breaking tray 13 exceeds the gas phase riser, it overflows to the top of the tray 10 below the breaking tray 13; the reason for cooling the liquid phase on the breaking tray 13 is to cool the raw gas after absorption, remove the absorption heat, increase the absorption driving force, and enhance the absorption effect;

[0062] S5: When the gas phase rises to the break tray 14 through the packing layer 11, the gas phase enters the packing layer 12 above the break tray 14, and the liquid falling from the packing layer 12 is intercepted on the break tray 14. The liquid phase on the break tray 14 is cooled and circulated into the packing layer 12. After the liquid level on the break tray 14 exceeds the gas phase riser, it overflows to the liquid distributor 26 at the bottom of the break tray 14; the reason for cooling the liquid phase on the break tray 14 is to cool the raw gas after absorption, remove the absorption heat, increase the absorption driving force, and enhance the absorption effect; the setting of the break tray 13 and the break tray 14 is to increase the two-stage circulation, increase the absorption liquid amount of the packing layer 11 and the packing layer 12, and thus improve the absorption efficiency;

[0063] S6: The gas phase passing through the packing layer 2 12 enters the desalted water liquid layer of the upper tray 2 15 through the multi-layer tray 2 15 in sequence, and the desalted water absorbs formaldehyde in the gas phase. The gas phase after absorbing formaldehyde is discharged through the exhaust pipeline and enters the subsequent treatment process; the liquid phase after absorbing formaldehyde passes through the packing layer 2 12, the broken tray 2 14, the packing layer 1 11, and the broken tray 1 13 to enter the upper part of the tray 1 10 of the tower kettle of the absorption tower body 1;

[0064] S7: The kettle of the absorption tower body 1 generates a formaldehyde product that meets the requirements. A part of the generated formaldehyde product is extracted from the kettle of the absorption tower body 1, and a part of it is recycled into the absorption tower body 1 to cycle and absorb formaldehyde. This can ensure that the formaldehyde concentration after absorption reaches more than 50%.

[0065] Embodiment 4:

[0066] This embodiment is described by using the existing silver-method formaldehyde absorption tower and the formaldehyde absorption tower of the present application to specifically illustrate the advantages of the present application:

[0067] Table 1 below shows the data of the existing silver-method formaldehyde absorption tower; Table 2 shows the data of the absorption tower of this application;

[0068]

[0069]

[0070] Table 1

[0071]

[0072]

[0073] Table 2

[0074] According to Table 1, we can get Figure 8 The temperature distribution in the tower of the prior art is shown as Fig. 9 The formaldehyde concentration distribution in the tower of the prior art shown in Table 2 can be obtained as follows: Fig.10 The temperature distribution in the tower of the present application is shown as Fig.11 The formaldehyde concentration distribution in the tower of the present application is shown.

[0075] Figure 8 , Fig. 9 The 9 on the horizontal axis represents the packing layer 1, the 8 on the horizontal axis represents the packing layer 2, and 7-1 represents the top tray. Figure 8 It can be seen that if the mass fraction of formaldehyde concentration in the bottom produced liquid is to be 0.5093, the absorption process is mainly completed in the two packing layers of packing layer 1 and packing layer 2. In this process, Figure 8 , Fig. 9 It can be seen that the formaldehyde concentration corresponding to the first packing layer in the tower bottom is about 50%, and the temperature corresponding to the first packing layer in the tower bottom is about 64°C. It can be seen that the concentration in the lower part is higher, but the temperature is relatively low, and it is easy for the packing layer to be blocked.

[0076] Fig.10 , Fig.11 The horizontal axis 10 represents the tray 10, the horizontal axis 9 represents the packing layer 11, the horizontal axis 8 represents the packing layer 2 12, and 7-1 represents the tray 2 15. Figure 8 , Fig. 9 It can be seen that the formaldehyde concentration corresponding to the tray 10 of the tower bottom is about 50%, and the temperature corresponding to the tray 10 of the tower bottom can reach about 76°C. It can be seen that the concentration of the tower bottom is high, but the temperature is relatively high, so it is not easy to get blocked; in addition, the concentrations of the packing layer 11 (about 36%) and the packing layer 12 (about 20%) of the present application are lower than those of the packing layer 1 (about 50%) and the packing layer 2 (about 30%) in the prior art. It can be seen that the formaldehyde concentrations corresponding to the packing layer 11 and the packing layer 12, which need to increase the absorption effect part, are lower, so they are not easy to get blocked; preferably, the present application can cool the material to a dew point of 80 degrees before feeding the tower, and correspondingly can release about 379KW of heat for utilization.

[0077] The devices, connection relationships, etc. not specifically described above all belong to the prior art and will not be described in detail in the present invention.

[0078] The preferred embodiments of the present application are described in detail above in conjunction with the accompanying drawings; however, the present application is not limited to the specific details in the above embodiments. Within the technical concept of the present application, a variety of simple modifications can be made to the technical solution of the present application, and these simple modifications all fall within the protection scope of the present application.

[0079] It should also be noted that the various specific technical features described in the above specific embodiments can be combined in any suitable manner without contradiction. In order to avoid unnecessary repetition, the various possible combinations of this application will not be described separately.

[0080] In addition, the various implementation modes of the present application may be arbitrarily combined, and as long as they do not violate the concept of the present application, they should also be regarded as the contents disclosed in the present application.

Claims

1. A formaldehyde absorption tower, comprising an absorption tower body (1), wherein a desalted water feed pipeline (2) and an exhaust pipeline (3) are arranged at the upper part of the absorption tower body (1); a feed pipeline (4) is connected to the lower part of the absorption tower body (1), and a formaldehyde extraction pipeline (7) is connected to the bottom of the absorption tower body (1), characterized in that: The absorption tower body (1) has a plurality of trays (10) disposed inside the bottom of the tower. The upper portion of the tray (10) is provided with a cut-off tray (13), a packing layer (11), a liquid distributor (26), a cut-off tray (14), a packing layer (12), a liquid distributor (27), and a tray (15) in sequence. A liquid outlet (16) is disposed between the cut-off tray (13) and the bottom of the packing layer (11). A liquid inlet (17) is disposed between the upper portion of the liquid distributor (26) and the lower portion of the cut-off tray (14) at a position corresponding to the absorption tower body (1). A circulation pipeline (18) is provided between the first liquid outlet (16) and the first liquid inlet (17), and a cooler (19) is provided on the first circulation pipeline (18). A second liquid outlet (21) is provided between the second break tower plate (14) and the lower part of the second packing layer (12). A second liquid inlet (22) is provided between the upper part of the second liquid distributor (27) and the second tower plate (15) at a position corresponding to the absorption tower body (1). A circulation pipeline (23) is provided between the second liquid outlet (21) and the second liquid inlet (22), and a cooler (24) is provided on the second circulation pipeline (23).

2. A formaldehyde absorption tower according to claim 1, characterized in that: The formaldehyde extraction pipeline (7) is connected to a tower bottom circulation pipeline (8), and the tower bottom circulation pipeline (8) is connected to the absorption tower body (1) corresponding to the upper part of the uppermost tower tray (10).

3. A formaldehyde absorption tower according to claim 1, characterized in that: The tower tray one (10) uses 5-10 layers of anti-blocking tower trays.

4. A formaldehyde absorption tower according to claim 1, characterized in that: The second tower tray (15) is a 12-20-layer anti-blocking tower tray.

5. A formaldehyde absorption tower according to claim 1, characterized in that: A feed cooler (5) is provided on the feed pipeline (4).

6. A formaldehyde absorption tower according to claim 5, characterized in that: A steam generator (6) is provided in front of the feed cooler (5).

7. A formaldehyde absorption tower according to claim 3 or 4, characterized in that: The anti-clogging tray comprises a tray body (28), a plurality of injection nozzles (29) are arranged on the tray body (28), a cap is installed on the tray body (28) corresponding to the injection nozzle (29), the cap comprises a cap body (31), the length and width of the injection nozzle (29) are smaller than the length and width of the cap projected on the tray body (28), a cap top plate (34) is arranged on the top of the cap body (31), a top gap (35) is provided between the cap top plate (34) and the cap body (31), the cap body (31) comprises two symmetrically arranged cap plates (32), two side plates (33) are symmetrically arranged between the two cap plates (32), a plurality of spoiler holes (36) are opened on the two side plates (33), and an inner spoiler plate (37) or an outer spoiler plate (38) is arranged on the side plate (33) above the spoiler holes (36).

8. A formaldehyde absorption tower according to claim 7, characterized in that: The injection nozzle (29) comprises a rectangular hole, the length and width of which are smaller than the length and width of the projection of the cap on the tray body (28), and an inclined injection plate (30) is installed at the edge of the rectangular hole, and the angle between the injection plate (30) and the vertical plane of the tray body (28) is 3°-6°.

9. A formaldehyde absorption method, characterized in that: The steps include: S1: Desalted water is introduced into the top of the absorption tower body (1), and the desalted water flows from the top of the absorption tower body (1) into the kettle of the absorption tower body (1); S2: The formaldehyde raw material is introduced into the bottom of the absorption tower body (1) through the feed pipeline (4); S3: The gas phase passes through the multiple layers of trays one (10) in sequence and enters the desalted water layer of the upper tray one (10). The gas and liquid phases are fully in contact, and the formaldehyde in the gas phase dissolves into the liquid phase, thereby achieving formaldehyde absorption; S4: When the gas phase treated by the multi-layer tower tray one (10) rises to the off-tower tray one (13), the gas phase enters the packing layer one (11) above the off-tower tray one (13), and the liquid falling from the packing layer one (11) is intercepted on the off-tower tray one (13). The liquid phase on the off-tower tray one (13) is cooled and then circulated into the packing layer one (11); the liquid level on the off-tower tray one (13) exceeds the gas phase riser and overflows to the top of the tower tray one (10) below the off-tower tray one (13); S5: When the gas phase rises from the packing layer 1 (11) to the break tray 2 (14), the gas phase enters the packing layer 2 (12) above the break tray 2 (14), and the liquid falling from the packing layer 2 (12) is intercepted on the break tray 2 (14). The liquid phase on the break tray 2 (14) is cooled and then circulated into the packing layer 2 (12); the liquid level on the break tray 2 (14) exceeds the gas phase riser and overflows to the liquid distributor 1 (26) below the break tray 2 (14); S6: The gas phase passing through the packing layer 2 (12) sequentially passes through the multi-layer tower tray 2 (15) into the desalted water liquid layer of the upper tower tray 2 (15), and the desalted water absorbs formaldehyde in the gas phase. The gas phase after absorbing formaldehyde is discharged through the exhaust pipeline (3), and the liquid phase passes through the packing layer 2 (12), the cut-off tower tray 2 (14), the packing layer 1 (11), and the cut-off tower tray 1 (13) into the top of the tower tray 1 (10) of the tower kettle of the absorption tower body (1); S7: The kettle of the absorption tower body (1) generates formaldehyde product. A part of the generated formaldehyde product is extracted from the kettle of the absorption tower body (1), and a part of the generated formaldehyde product is circulated into the upper part of the uppermost tray 1 (10) in the absorption tower body (1) to absorb formaldehyde in a circulated manner.

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