Single-stage absorption tower for removing formaldehyde in industrial waste gas by using urea solution

Abstract

The utility model discloses a single-stage absorption tower for removing formaldehyde in industrial waste gas by using a urea solution. The single-stage absorption tower comprises a tower body, a gas mixing and distributing system and an absorption liquid spraying system, according to the utility model, compressed air is introduced and heated by utilizing the gas mixing and distributing system, then industrial waste gas is mixed with the compressed air, and the mixed gas is sprayed into mist through the gas distributor, so that the industrial waste gas is uniformly distributed in the packing layer; the absorption liquid spraying system atomizes a urea solution in an absorption liquid storage pool at the bottom of the tower body into tiny liquid drops, the tiny liquid drops are evenly sprayed to the filler layer, and the urea solution reacts with formaldehyde in the industrial waste gas to generate urea resin. The formaldehyde absorption efficiency and the reaction efficiency of formaldehyde and urea are greatly improved through the measures of introducing heated compressed air, atomizing and distributing the gas distributor, increasing the gas-liquid contact area by the filler and the like, and the resource utilization of formaldehyde in industrial waste gas can be realized while secondary pollution is avoided.

Description

TECHNICAL FIELD

[0001] The utility model belongs to the technical field of waste gas treatment, specifically relates to a single stage absorption tower for removing formaldehyde in industrial waste gas by urea solution. BACKGROUND

[0002] Formaldehyde is a common industrial raw material, widely used in chemical industry, wood processing, textile, pharmaceutical and other industries. However, formaldehyde is also a toxic and harmful substance, which causes serious harm to human health and environment. A large amount of formaldehyde-containing waste gas is generated in the process of industrial production, which will cause serious pollution to the atmospheric environment if directly discharged, so it is necessary to effectively treat the formaldehyde in industrial waste gas. At present, the removal methods of formaldehyde in industrial waste gas mainly include the following several kinds: membrane absorption method, adsorption method, nanometer material catalysis, photocatalytic oxidation and biological method, etc. Although the existing technology can treat formaldehyde waste gas to some extent, there are still limitations, such as complex process, high investment cost, long cycle and low efficiency, etc., so it is difficult to popularize and promote in practical application.

[0003] Formaldehyde has good reactivity with phenol, melamine, urea and sodium sulfite in aqueous solution, so the aqueous solution of these substances can be used to absorb industrial formaldehyde waste gas, so as to achieve the purpose of removing formaldehyde. Among them, urea is a cheap and readily available chemical raw material, and its aqueous solution can react with formaldehyde to generate stable urea-formaldehyde resin, thereby reducing the content of formaldehyde in water. In addition, the generated urea-formaldehyde resin can also be recycled and utilized, realizing the resource utilization of formaldehyde gas. The urea method for removing formaldehyde has the following advantages: 1. fast reaction speed; 2. high removal efficiency; 3. low cost; 4. safe and environmentally friendly.

[0004] After searching, the existing Chinese patent CN201721269547.7 provides a device for removing formaldehyde in indoor air, characterized in that it comprises a shell, the top surface of the shell is open, and the inside is horizontally arranged with a first filter layer, a second filter layer, a third filter layer and an adsorption layer from bottom to top; a gas inlet and a urea spray port are arranged on the side wall of the shell; the gas inlet is located below the first filter layer, and the urea spray port is located between the third filter layer and the adsorption layer. The utility model constructs a formaldehyde reaction bin, and the atomized urea absorbs formaldehyde, which can degrade the formaldehyde in indoor air and also filter the free dust and harmful gas in the air to some extent. The device can efficiently and quickly remove formaldehyde in the air, and has low use cost and is green and pollution-free. Although the above-mentioned patent can remove indoor formaldehyde, there is still no technology for treating formaldehyde in industrial waste gas based on urea solution at present.

[0005] Based on the limitations of the prior art and the advantages of urea absorption technology, it has important practical significance to adopt the technology of absorbing formaldehyde in industrial waste gas by urea. The technology not only can meet the increasingly strict environmental protection policy requirements, but also can reduce the cost of enterprises under the condition of ensuring the normal and stable operation of the factory, and promote the progress of industrial waste gas treatment technology. Practical new type content

[0006] Therefore, the utility model discloses a kind of single-stage absorption tower for removing formaldehyde in industrial waste gas by urea solution, structure is simple, low in cost, removal efficiency is high, and there is no secondary pollution.

[0007] To achieve the above object, the utility model provides the following technical scheme:

[0008] The utility model discloses a kind of single-stage absorption tower for removing formaldehyde in industrial waste gas by urea solution, the single-stage absorption tower includes tower body, gas mixing distribution system and absorption liquid spraying system;

[0009] The bottom of the tower body is provided with an absorption liquid storage pool, the middle part of the tower body is provided with a filler layer, and the top of the tower body is provided with a gas outlet;

[0010] The gas mixing distribution system includes a waste gas inlet pipe, a compressed air pipe, a fan and a gas distributor, a pre-filter is provided on the waste gas inlet pipe, the fan is communicated with the compressed air pipe, a gas heating device is provided on the compressed air pipe, the waste gas inlet pipe and the compressed air pipe are communicated with the gas distributor after being converged, and the gas distributor is arranged between the absorption liquid storage pool and the filler layer in the tower body;

[0011] The absorption liquid spraying system includes a circulating pump, a spraying device and a circulating pipe, the spraying device is arranged above the filler layer in the tower body, one end of the circulating pipe is communicated with the absorption liquid storage pool, the other end is communicated with the spraying device, and the circulating pump is arranged on the circulating pipe.

[0012] As a preferred technical scheme, the gas mixing distribution system further includes a formaldehyde real-time monitor, and the formaldehyde real-time monitor is arranged on the waste gas inlet pipe to monitor the formaldehyde concentration of the waste gas.

[0013] As a preferred technical scheme, the cross section of the gas distributor is a disc shape matched with the size of the tower body, a first jet hole is arranged in the middle of the disc shape in a ring shape, and a second jet hole is arranged on the periphery of the first jet hole in a radial direction.

[0014] As a preferred technical scheme, the gas heating device includes a shell, one end of the shell is a cold gas inlet, the other end of the shell is a hot gas outlet, and a plurality of heating rods are vertically arranged between the cold gas inlet and the hot gas outlet in the shell.

[0015] As a preferred technical solution, a filtration device is also provided above the spraying device inside the tower.

[0016] As a preferred technical solution, an observation window is provided in the middle of the tower body, and an inspection port is provided at the top of the tower body.

[0017] As a preferred technical solution, the single-stage absorption tower further includes an absorbent replenishment system, which includes a drain pipe and a replenishment pipe that are respectively connected to the absorbent storage tank, and a replenishment pump is provided on the replenishment pipe.

[0018] The beneficial effects of this utility model are as follows:

[0019] This invention utilizes a gas mixing and distribution system to introduce and heat compressed air, then mixes industrial waste gas with the compressed air. The mixture is then atomized into a mist by a gas distributor to ensure uniform distribution of the waste gas throughout the packing layer. Meanwhile, an absorbent spraying system atomizes urea solution from the absorbent storage tank at the bottom of the tower into tiny droplets, which are then evenly sprayed onto the packing layer. The urea solution reacts with formaldehyde in the waste gas to form urea-formaldehyde resin. By introducing heated compressed air, using a gas distributor for atomization, and increasing the gas-liquid contact area with the packing layer, this invention significantly improves formaldehyde absorption efficiency and the reaction efficiency between formaldehyde and urea, achieving resource utilization of formaldehyde in industrial waste gas without secondary pollution. Attached Figure Description

[0020] To make the objectives, technical solutions, and beneficial effects of this utility model clearer, the following drawings are provided for illustration:

[0021] Figure 1 This is a schematic diagram of the structure of the single-stage absorption tower of this utility model.

[0022] Figure 2 This is a schematic diagram of a gas distributor.

[0023] Figure 3 This is a schematic diagram of a gas heating device. Detailed Implementation

[0024] The present invention will be further described below with reference to the accompanying drawings and specific embodiments, so that those skilled in the art can better understand and implement the present invention. However, the embodiments are not intended to limit the present invention.

[0025] like Figure 1 The diagram shows a single-stage absorption tower for removing formaldehyde from industrial waste gas using urea solution. The single-stage absorption tower includes a tower body 1, a gas mixing and distribution system, an absorbent spraying system, and an absorbent replenishment system.

[0026] The tower body 1 is provided with an absorption liquid storage pool 2 at the bottom, which stores the recycled urea solution; the tower body 1 is provided with a filler layer 3 in the middle, which can be provided with several layers to enhance the absorption effect; and the tower body 1 is provided with an air outlet 4 at the top.

[0027] The gas mixing and distribution system comprises a waste gas inlet pipe 5, a compressed air pipe 6, a fan 7 and a gas distributor 8, the waste gas inlet pipe 5 is provided with a pre-filter 9, the fan 7 is communicated with the compressed air pipe 6, the compressed air pipe 6 is provided with a gas heating device 10, the waste gas inlet pipe 5 and the compressed air pipe 6 are communicated with the gas distributor 8 after being converged, and the gas distributor 8 is arranged between the absorption liquid storage pool 2 and the filler layer 3 in the tower body 1.

[0028] The gas mixing and distribution system further comprises a formaldehyde real-time monitor 11, which is arranged on the waste gas inlet pipe 5 to monitor the formaldehyde concentration of the waste gas.

[0029] As shown in Figure 2 The cross section of the gas distributor 8 is a disc shape matched with the size of the tower body, the disc shape is provided with a first jet hole 12 arranged in a ring shape in the middle, and the periphery of the first jet hole 12 is provided with a second jet hole 13 arranged in a radial direction.

[0030] As shown in Figure 3 The gas heating device 10 comprises a shell, one end of the shell is a cold gas inlet 14, the other end of the shell is a hot gas outlet 15, and a plurality of heating rods 16 are vertically arranged between the cold gas inlet 14 and the hot gas outlet 15 in the shell.

[0031] The absorption liquid spraying system comprises a circulating pump 17, a spraying device 18 and a circulating pipe 19, the spraying device 18 is arranged above the filler layer 3 in the tower body 1, one end of the circulating pipe 19 is communicated with the absorption liquid storage pool 2, the other end of the circulating pipe 19 is communicated with the spraying device 18, and the circulating pump 17 is arranged on the circulating pipe 19.

[0032] The absorption liquid supplementing system comprises a liquid discharge pipe 20 and a liquid supplementing pipe 21 which are respectively communicated with the absorption liquid storage pool 2, and the liquid supplementing pipe 21 is provided with a liquid supplementing pump 22.

[0033] The tower body 1 is further provided with a filtering device 23 above the spraying device 18, the tower body 1 is provided with an observation window 24 in the middle, and the tower body 1 is provided with an inspection port 25 at the top.

[0034] The working process of the utility model is: the industrial waste gas firstly enters the pre-filter 9 through the waste gas inlet pipe 5 for filtration, while the fan 7 blows in and heats the compressed air through the gas heating device 10, the heated compressed air is mixed with the industrial waste gas, the mixed gas is sprayed into mist through the gas distributor 8 and then moves upward and distributes into the filler layer 3; the circulating pump 17 draws the urea solution in the absorption liquid storage pool 2 and sends it into the spraying device 18, the urea solution is atomized into tiny droplets through the spraying device 18 and is uniformly sprayed onto the filler layer 3; the urea solution reacts with the formaldehyde in the industrial waste gas to generate urea-formaldehyde resin in the filler layer 3; then the waste gas is filtered again through the filtering device 23 and finally is discharged from the gas outlet 4 of the tower body 1. The formaldehyde real-time monitor 11 is used for real-time monitoring of the formaldehyde concentration, according to the real-time monitored formaldehyde concentration, the spraying amount and the circulating flow of the urea solution are adjusted to control the molar ratio of formaldehyde and urea within the suitable range, so that the best removal effect is achieved. In addition, according to the waste gas flow and the change of the formaldehyde concentration, the operating parameters of the gas heating device 10 are dynamically adjusted to ensure the stability of the reaction conditions. The liquid discharge pipe 20 and the liquid supplement pipe 21 discharge and supplement the liquid in real time according to the consumption amount of the urea solution in the absorption liquid storage pool 2.

[0035] The above-described embodiments are only preferred embodiments for fully illustrating the utility model, and the protection scope of the utility model is not limited thereto. The equivalent substitutions or transformations made by the person skilled in the art on the basis of the utility model are all within the protection scope of the utility model. The protection scope of the utility model is subject to the claims.

Claims

1. A single stage absorption tower for removal of formaldehyde from industrial exhaust gas using urea solution, characterized in that: The single-stage absorption tower comprises a tower body, a gas mixing distribution system and an absorption liquid spraying system. The bottom of the tower body is provided with an absorption liquid storage pool, the middle part of the tower body is provided with a filler layer, and the top of the tower body is provided with a gas outlet. The gas mixing distribution system comprises a waste gas inlet pipe, a compressed air pipe, a fan and a gas distributor, the waste gas inlet pipe is provided with a pre-filter, the fan is communicated with the compressed air pipe, the compressed air pipe is provided with a gas heating device, the waste gas inlet pipe and the compressed air pipe are communicated with the gas distributor after being converged, and the gas distributor is arranged between the absorption liquid storage pool and the filler layer in the tower body. The absorption liquid spraying system comprises a circulating pump, a spraying device and a circulating pipe, the spraying device is arranged above the filler layer in the tower body, one end of the circulating pipe is communicated with the absorption liquid storage pool, the other end of the circulating pipe is communicated with the spraying device, and the circulating pump is arranged on the circulating pipe.

2. A single stage absorption tower for removal of formaldehyde from industrial exhaust gas using urea solution as claimed in claim 1, wherein: The gas mixing distribution system further comprises a formaldehyde real-time monitor, and the formaldehyde real-time monitor is arranged on the waste gas inlet pipe and used for monitoring the formaldehyde concentration of waste gas.

3. A single stage absorption tower for removal of formaldehyde from industrial exhaust gas using urea solution as claimed in claim 1, wherein: The cross section of the gas distributor is a disc shape matched with the size of the tower body, a first jet hole in a ring shape is arranged in the middle part of the disc shape, and a second jet hole in a radial shape is arranged outside the first jet hole in a ring shape.

4. A single stage absorption tower for removal of formaldehyde from industrial exhaust gas using urea solution as claimed in claim 1, wherein: The gas heating device comprises a shell, one end of the shell is a cold gas inlet, the other end of the shell is a hot gas outlet, and a plurality of heating rods are vertically arranged between the cold gas inlet and the hot gas outlet in the shell.

5. A single stage absorption tower for removal of formaldehyde from industrial exhaust gas using urea solution as claimed in claim 1, wherein: The tower body is further provided with a filtering device above the spraying device.

6. A single stage absorption tower for removal of formaldehyde from industrial exhaust gas using urea solution as claimed in claim 1, wherein: The middle part of the tower body is provided with an observation window, and the top of the tower body is provided with an inspection port.

7. A single stage absorption tower for removal of formaldehyde from industrial exhaust gas using urea solution as claimed in claim 1, wherein: The single-stage absorption tower further comprises an absorption liquid supplement system, the absorption liquid supplement system comprises a liquid discharge pipe and a liquid supplement pipe which are communicated with the absorption liquid storage pool respectively, and the liquid supplement pipe is provided with a liquid supplement pump.

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