Disqualified formaldehyde recycling system

Abstract

The utility model discloses an unqualified formaldehyde recycling system which comprises a formaldehyde absorption tower, and a first absorption section, a second absorption section and a third absorption section are sequentially arranged in the formaldehyde absorption tower from top to bottom; a liquid inlet spraying pipe and a liquid return spraying pipe are arranged at the top of the first absorption section, a liquid outlet of the first absorption section is communicated with a tube pass inlet of the first heat exchanger through a first conveying pipeline, a first electromagnetic valve is arranged on the first conveying pipeline close to the liquid outlet of the first absorption section, and a tube pass outlet of the first heat exchanger is communicated with an inlet of the liquid return spraying pipe; a liquid outlet of the formaldehyde absorption tower is communicated with a tube pass inlet of a third heat exchanger through a third conveying pipeline, a third conveying pump is arranged on the third conveying pipeline close to the liquid outlet of the formaldehyde absorption tower, and a tube pass outlet of the third heat exchanger is communicated with an inlet of a product storage tank; a second outlet of the product storage tank is communicated with the first conveying pipeline through a liquid return pipeline, and a fifth electromagnetic valve is arranged on the liquid return pipeline.

Description

Technical field:

[0001] The utility model relates to the technical field of formaldehyde recovery, in particular to a system for recovering and utilizing unqualified formaldehyde. Background technology:

[0002] The formaldehyde absorption tower is a key equipment for preparing formaldehyde solution. In the formaldehyde absorption tower, formaldehyde gas moves from bottom to top, while the absorption liquid flows from top to bottom. The two are in countercurrent contact. The absorption liquid absorbs the formaldehyde gas, causing its concentration to increase continuously. When a certain concentration is reached, industrial formaldehyde products are obtained.

[0003] At present, the formaldehyde solution production index of enterprises is 47-55% (wt%). In the initial stage of operation, a large amount of unqualified formaldehyde will be produced, with a concentration of about 10-40% (wt%). The traditional treatment method is: first transport and store the unqualified products in the tank area, and then add the unqualified products to the qualified formaldehyde in small quantities and multiple times, and send them to the downstream section for consumption.

[0004] However, the above method has the following problems: 1. The amount of unqualified formaldehyde added each time is small, and multiple additions take a long time. The storage time of unqualified formaldehyde is long, and there is a risk of formaldehyde leakage; 2. Since the concentration and acidity of formaldehyde added each time cannot be guaranteed, it is very easy to cause downstream products to be unqualified, affecting the quality of qualified products. Utility model content:

[0005] The utility model aims to provide a system for recycling unqualified formaldehyde.

[0006] The utility model is implemented by the following technical scheme: a system for recycling unqualified formaldehyde, which comprises a formaldehyde absorption tower, a first heat exchanger, a third heat exchanger and a product storage tank; the formaldehyde absorption tower is divided into a first absorption section, a second absorption section and a third absorption section from top to bottom by two spaced partitions, and each absorption section is provided with a packing layer;

[0007] A liquid inlet spray pipe and a liquid return spray pipe are provided above the packing layer of the first absorption section, the liquid discharge port of the first absorption section is connected with the tube side inlet of the first heat exchanger through a first delivery pipeline, a first solenoid valve is provided on the first delivery pipeline near the liquid discharge port of the first absorption section, and the tube side outlet of the first heat exchanger is connected with the inlet of the liquid return spray pipe; the liquid discharge port of the formaldehyde absorption tower is connected with the tube side inlet of the third heat exchanger through a third delivery pipeline, a third delivery pump is provided on the third delivery pipeline near the liquid discharge port of the formaldehyde absorption tower, the tube side outlet of the third heat exchanger is connected with the inlet of the product storage tank, and the first outlet of the product storage tank is connected with a qualified product delivery pipeline; the second outlet of the product storage tank is connected with the first delivery pipeline through a liquid return pipeline, a fifth solenoid valve is provided on the liquid return pipeline, and a first delivery pump is provided on the first delivery pipeline between the outlet of the liquid return pipeline and the tube side inlet of the first heat exchanger.

[0008] Preferably, an air inlet is provided on the bottom side wall of the formaldehyde absorption tower, an exhaust port is provided on the top of the formaldehyde absorption tower, and a liquid discharge port is provided on the bottom of the formaldehyde absorption tower; liquid distributors are respectively provided above the packing layers of the second absorption section and the third absorption section, and each of the liquid distributors is respectively provided with a liquid inlet pipeline passing through the side wall of the formaldehyde absorption tower; overflow pipes and ventilation pipelines are provided on the partitions at the bottom of the first absorption section and the second absorption section.

[0009] Preferably, the third delivery pipeline is connected to a circulation pipeline, the outlet of the circulation pipeline is connected to the liquid inlet pipeline of the third absorption section, and a second solenoid valve is provided on the circulation pipeline; a third solenoid valve is provided on the third delivery pipeline between the inlet of the circulation pipeline and the tube inlet of the third heat exchanger.

[0010] Preferably, the discharge port of the second absorption section is connected to the tube side inlet of the second heat exchanger through a second delivery pipeline, a circulation pump is provided on the second delivery pipeline, and the tube side outlet of the second heat exchanger is connected to the inlet of the liquid inlet pipeline of the second absorption section.

[0011] Preferably, a temperature sensor is provided in the product storage tank, the temperature sensor is electrically connected to the input end of the controller, and the output end of the controller is electrically connected to the circulation pump.

[0012] Preferably, a concentration detector is provided in the product storage tank, the concentration detector is electrically connected to the input end of the controller, and the output end of the controller is electrically connected to the fourth solenoid valve and the fifth solenoid valve respectively.

[0013] The utility model has the advantages that the utility model directly delivers a large amount of unqualified formaldehyde solution generated at the initial start-up to the product storage tank. When the concentration detector in the product storage tank detects that the concentration of the formaldehyde solution is between 10% and 40% (wt%), the controller controls the fourth solenoid valve to close and the fifth solenoid valve to open. The unqualified formaldehyde solution in the product storage tank enters the first heat exchanger through the first delivery pump to cool down, and then re-enters the first absorption section through the return liquid pipeline and the return liquid spray pipe in sequence to continue to absorb formaldehyde gas. The above process is repeated to continuously circulate the unqualified formaldehyde solution in the product storage tank until formaldehyde with a qualified concentration is produced; when the concentration of the formaldehyde solution is between 47% and 55% (wt%), the controller controls the fifth solenoid valve to close and the fourth solenoid valve to open, and the formaldehyde solution is discharged through the qualified product delivery pipeline; the above process does not require the setting of a large-volume unqualified formaldehyde storage tank for long-term storage of formaldehyde, which can reduce the risk of formaldehyde leakage; and at the same time, it is avoided that unqualified formaldehyde is mixed into qualified formaldehyde in the downstream section in small amounts and multiple times, which can ensure the stability of product quality. Description of the drawings:

[0014] In order to more clearly illustrate the embodiments of the utility model or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the utility model. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0015] Figure 1 It is a structural schematic diagram of the utility model.

[0016] Figure 2 It is a schematic diagram of the control principle of the utility model.

[0017] The components in the accompanying drawings are marked as follows: formaldehyde absorption tower 1, first absorption section 1.1, second absorption section 1.2, third absorption section 1.3, first heat exchanger 2, second heat exchanger 3, third heat exchanger 4, product storage tank 5, partition 6, packing layer 7, liquid inlet spray pipe 8, liquid return spray pipe 9, liquid distributor 10, liquid inlet pipeline 11, overflow pipe 12, ventilation pipeline 13, first delivery pipeline 14, first solenoid valve 15, third delivery pipeline 16, circulation pipeline 17, second solenoid valve 18, third delivery pump 19, third solenoid valve 20, qualified product delivery pipeline 21, fourth solenoid valve 22, liquid return pipeline 23, fifth solenoid valve 24, first delivery pump 25, concentration detector 26, controller 27, second delivery pipeline 28, circulation pump 29, temperature sensor 30. Specific implementation method:

[0018] The following will be combined with the drawings in the embodiments of the utility model to clearly and completely describe the technical solutions in the embodiments of the utility model. Obviously, the described embodiments are only part of the embodiments of the utility model, not all of the embodiments. Based on the embodiments of the utility model, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the utility model.

[0019] like Figure 1-Figure 2 As shown, a system for recycling unqualified formaldehyde includes a formaldehyde absorption tower 1, a first heat exchanger 2, a second heat exchanger 3, a third heat exchanger 4 and a product storage tank 5;

[0020] An air inlet is provided on the bottom side wall of the formaldehyde absorption tower 1, and formaldehyde gas enters through the air inlet of the formaldehyde absorption tower 1. An exhaust port is provided on the top of the formaldehyde absorption tower 1, and insoluble gas is discharged through the exhaust port of the formaldehyde absorption tower 1. A liquid discharge port is provided at the bottom of the formaldehyde absorption tower 1, and formaldehyde solution is discharged through the liquid discharge port of the formaldehyde absorption tower 1. The formaldehyde absorption tower 1 is divided into a first absorption section 1.1, a second absorption section 1.2 and a third absorption section 1.3 from top to bottom through two spaced-apart partitions 6, and each absorption section is provided with a packing layer 7; a liquid inlet spray pipe 8 and a liquid return spray pipe 9 are provided above the packing layer 7 of the first absorption section 1.1, and the transverse pipes of the liquid inlet spray pipe 8 and the liquid return spray pipe 9 are alternately arranged, and the absorption liquid enters through the liquid inlet spray pipe 8, and the circulating liquid continues to spray through the liquid return spray pipe 9 to improve the uniformity of the spray; the second absorption section 1.2 and the third absorption section 1.3 are divided above the packing layer 7 A liquid distributor 10 is separately provided, and each liquid distributor 10 is respectively provided with a liquid inlet pipeline 11 passing through the side wall of the formaldehyde absorption tower 1. The circulating liquid enters the liquid distributor 10 through the liquid inlet pipeline 11 and is evenly distributed through the liquid distributor 10. An overflow pipe 12 and a venting pipeline 13 are provided on the baffle 6 at the bottom of the first absorption section 1.1 and the second absorption section 1.2. The formaldehyde gas passes through the third absorption section 1.3, the second absorption section 1.2 and the first absorption section 1.1 from bottom to top in sequence through the venting pipeline 13, and the overflow pipe 12 plays an overflow role; since the absorption process of formaldehyde gas is an exothermic process, the temperature of the absorption liquid will increase after the absorption of formaldehyde. The higher the temperature of the absorption liquid, the smaller the solubility of the formaldehyde gas, which is not conducive to the absorption. Therefore, in the circulation process of the absorption liquid, the first heat exchanger 2, the second heat exchanger 3, and the third heat exchanger 4 are provided to reduce the temperature of the absorption liquid to avoid affecting the absorption of formaldehyde gas;

[0021] The discharge port of the first absorption section 1.1 is connected to the tube side inlet of the first heat exchanger 2 through a first delivery pipeline 14. A first solenoid valve 15 is provided on the first delivery pipeline 14 near the discharge port of the first absorption section 1.1. The tube side outlet of the first heat exchanger 2 is connected to the inlet of the return liquid spray pipe 9 through a pipeline, and the absorption liquid in the first absorption section 1.1 is cooled by the first heat exchanger 2.

[0022] The liquid discharge port of the formaldehyde absorption tower 1 is connected to the pipe side inlet of the third heat exchanger 4 through a third delivery pipeline 16, and a circulation pipeline 17 is connected to the third delivery pipeline 16. The outlet of the circulation pipeline 17 is connected to the liquid inlet pipeline 11 of the third absorption section 1.3, and a second solenoid valve 18 is provided on the circulation pipeline 17; a third delivery pump 19 is provided on the third delivery pipeline 16 between the liquid discharge port of the formaldehyde absorption tower 1 and the inlet of the circulation pipeline 17, and a third solenoid valve 20 is provided on the third delivery pipeline 16 between the inlet of the circulation pipeline 17 and the pipe side inlet of the third heat exchanger 4. The formaldehyde solution at the bottom of the formaldehyde absorption tower 1 is delivered to the third delivery pipeline 16 by the third delivery pump 19, and a part of the formaldehyde solution in the third delivery pipeline 16 returns to the third absorption section 1.3 through the circulation pipeline 17, and circulates continuously in the third absorption section 1.3 to continuously increase the concentration of the formaldehyde solution, and the formaldehyde solution in the third delivery pipeline 16 Another part of the formaldehyde solution enters the third heat exchanger 4 and is cooled by the third heat exchanger 4; the tube side outlet of the third heat exchanger 4 is connected to the inlet of the product storage tank 5 through a pipeline, and the cooled formaldehyde solution enters the product storage tank 5 for storage, and the first outlet of the product storage tank 5 is connected to the qualified product delivery pipeline 21, and the qualified product delivery pipeline 21 is provided with a fourth solenoid valve 22; the second outlet of the product storage tank 5 is connected to the first delivery pipeline 14 through a liquid return pipeline 23, and a fifth solenoid valve 24 is provided on the liquid return pipeline 23, and a first delivery pump 25 is provided on the first delivery pipeline 14 between the outlet of the liquid return pipeline 23 and the tube side inlet of the first heat exchanger 2, and the first delivery pump 25 can make the formaldehyde solution in the first absorption section 1.1 circulate continuously in the first absorption section 1.1, and at the same time, the unqualified formaldehyde solution in the product storage tank 5 can enter the first absorption section 1.1 through the liquid return pipeline 23 for continuous spraying;

[0023] A concentration detector 26 is provided in the product storage tank 5. The concentration detector 26 is electrically connected to the input end of the controller 27. The output end of the controller 27 is electrically connected to the fourth solenoid valve 22 and the fifth solenoid valve 24 respectively. The concentration of the formaldehyde solution is detected by the concentration detector 26. When the concentration of the formaldehyde solution is between 10% and 40% (wt%), the controller 27 controls the fourth solenoid valve 22 to close and the fifth solenoid valve 24 to open. The unqualified formaldehyde solution in the product storage tank 5 enters the first heat exchanger 2 through the first delivery pump 25, enters the return liquid spray pipe 9 through the return liquid pipeline 23 after cooling, and enters the first absorption section 1.1 through the return liquid spray pipe 9 to continue absorbing formaldehyde gas until formaldehyde with a qualified concentration is produced; when the concentration of the formaldehyde solution is between 47% and 55% (wt%), the controller 27 controls the fifth solenoid valve 24 to close and the fourth solenoid valve 22 to open, and the formaldehyde solution is discharged through the qualified product delivery pipeline 21.

[0024] The discharge port of the second absorption section 1.2 is connected to the tube side inlet of the second heat exchanger 3 through a second delivery pipeline 28, and a circulation pump 29 is provided on the second delivery pipeline 28. The tube side outlet of the second heat exchanger 3 is connected to the inlet of the liquid inlet pipeline 11 of the second absorption section 1.2 through a pipeline; a temperature sensor 30 is provided in the product storage tank 5, and the temperature sensor 30 is electrically connected to the input end of the controller 27, and the output end of the controller 27 is electrically connected to the circulation pump 29. The temperature of the qualified formaldehyde solution is detected by the temperature sensor 30. When it is detected that the temperature of the qualified formaldehyde solution exceeds the set maximum value, the controller 27 controls the circulation pump 29 to start, and the formaldehyde solution in the second absorption section 1.2 is transported to the second heat exchanger 3 through the circulation pump 29. During the circulation process, the formaldehyde solution is cooled by the second heat exchanger 3. When it is detected that the temperature of the qualified formaldehyde solution is within the set range, the controller 27 controls the circulation pump 29 to stop running.

[0025] Working process: formaldehyde gas enters through the air inlet of the formaldehyde absorption tower 1, passes through the third absorption section 1.3, the second absorption section 1.2 and the first absorption section 1.1 from bottom to top through the ventilation pipeline 13, and the absorption liquid enters through the liquid inlet spray pipe 8, flows from top to bottom into the first absorption section 1.1, the formaldehyde gas moves from bottom to top, and the absorption liquid flows from top to bottom, the two are in countercurrent contact, and the absorption liquid absorbs the formaldehyde gas. When the liquid level at the bottom of the first absorption section 1.1 is higher than the overflow pipe 12, the absorption liquid at the bottom of the first absorption section 1.1 overflows into the second absorption section 1.2 through the overflow pipe 12. Similarly, when the liquid level at the bottom of the second absorption section 1.2 is higher than the overflow pipe 12, the absorption liquid at the bottom of the second absorption section 1.2 overflows into the third absorption section 1.3 through the overflow pipe 12. In the process of the absorption liquid flowing downward, the concentration of the formaldehyde solution continues to increase;

[0026] In the above process, the first delivery pump 25 and the third delivery pump 19 are started at the same time, and the first solenoid valve 15, the second solenoid valve 18, and the third solenoid valve 20 are opened. At the initial start-up, the concentration of the formaldehyde solution is low, and the formaldehyde solution in the first absorption section 1.1 is delivered to the first heat exchanger 2 by the first delivery pump 25, and after cooling, enters the first absorption section 1.1 through the return liquid spray pipe 9 to continue to absorb formaldehyde gas; the unqualified formaldehyde solution at the bottom of the formaldehyde absorption tower 1 enters the third delivery pipeline 16 through the third delivery pump 19, and a part of the unqualified formaldehyde solution in the third delivery pipeline 16 returns to the third absorption section 1.3 through the circulation pipeline 17, and another part of the unqualified formaldehyde solution in the third delivery pipeline 16 enters the product storage tank 5 through the third heat exchanger 4;

[0027] When the concentration detector 26 in the product storage tank 5 detects that the formaldehyde concentration is lower than the set minimum value, the controller 27 controls the fourth solenoid valve 22 to close and the fifth solenoid valve 24 to open, and the unqualified formaldehyde solution in the product storage tank 5 enters the first heat exchanger 2 through the first delivery pump 25, and after cooling, enters the first absorption section 1.1 through the liquid return spray pipe 9 to continue absorbing formaldehyde gas until the formaldehyde with qualified concentration is produced;

[0028] When the concentration detector 26 in the product storage tank 5 detects that the formaldehyde concentration is within the set range, the controller 27 controls the fifth solenoid valve 24 to close and the fourth solenoid valve 22 to open, and the formaldehyde solution is discharged through the qualified product delivery pipeline 21;

[0029] During the circulation of the formaldehyde solution, when the temperature sensor 30 in the product storage tank 5 detects that the temperature of the qualified formaldehyde solution exceeds the set maximum value, the controller 27 controls the circulation pump 29 to start, and the formaldehyde solution in the second absorption section 1.2 is transported to the second heat exchanger 3 through the circulation pump 29, and the formaldehyde solution is cooled by the second heat exchanger 3. When the temperature sensor 30 in the product storage tank 5 detects that the temperature of the qualified formaldehyde solution is within the set range, the controller 27 controls the circulation pump 29 to stop running.

[0030] The above are only preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A system for recycling unqualified formaldehyde, characterized in that: It includes a formaldehyde absorption tower, a first heat exchanger, a third heat exchanger and a product storage tank; the formaldehyde absorption tower is divided into a first absorption section, a second absorption section and a third absorption section from top to bottom by two spaced partitions, and each absorption section is provided with a packing layer; A liquid inlet spray pipe and a liquid return spray pipe are provided above the packing layer of the first absorption section, the liquid discharge port of the first absorption section is connected with the tube side inlet of the first heat exchanger through a first delivery pipeline, a first solenoid valve is provided on the first delivery pipeline near the liquid discharge port of the first absorption section, and the tube side outlet of the first heat exchanger is connected with the inlet of the liquid return spray pipe; the liquid discharge port of the formaldehyde absorption tower is connected with the tube side inlet of the third heat exchanger through a third delivery pipeline, a third delivery pump is provided on the third delivery pipeline near the liquid discharge port of the formaldehyde absorption tower, the tube side outlet of the third heat exchanger is connected with the inlet of the product storage tank, and the first outlet of the product storage tank is connected with a qualified product delivery pipeline; a fourth solenoid valve is provided on the qualified product delivery pipeline, the second outlet of the product storage tank is connected with the first delivery pipeline through a liquid return pipeline, a fifth solenoid valve is provided on the liquid return pipeline, and a first delivery pump is provided on the first delivery pipeline between the outlet of the liquid return pipeline and the tube side inlet of the first heat exchanger.

2. A system for recycling unqualified formaldehyde according to claim 1, characterized in that: An air inlet is provided on the bottom side wall of the formaldehyde absorption tower, an exhaust port is provided on the top of the formaldehyde absorption tower, and a liquid discharge port is provided on the bottom of the formaldehyde absorption tower; liquid distributors are respectively provided above the packing layers of the second absorption section and the third absorption section, and each of the liquid distributors is respectively provided with a liquid inlet pipeline passing through the side wall of the formaldehyde absorption tower; overflow pipes and ventilation pipelines are provided on the partitions at the bottom of the first absorption section and the second absorption section.

3. A system for recycling unqualified formaldehyde according to claim 2, characterized in that: The third delivery pipeline is connected to a circulation pipeline, the outlet of the circulation pipeline is connected to the liquid inlet pipeline of the third absorption section, and a second solenoid valve is provided on the circulation pipeline; a third solenoid valve is provided on the third delivery pipeline between the inlet of the circulation pipeline and the tube inlet of the third heat exchanger.

4. A system for recycling unqualified formaldehyde according to claim 2 or 3, characterized in that: The discharge port of the second absorption section is connected to the tube side inlet of the second heat exchanger through a second delivery pipeline. A circulating pump is provided on the second delivery pipeline. The tube side outlet of the second heat exchanger is connected to the inlet of the liquid inlet pipeline of the second absorption section.

5. A system for recycling unqualified formaldehyde according to claim 4, characterized in that: A temperature sensor is provided in the product storage tank, the temperature sensor is electrically connected to the input end of the controller, and the output end of the controller is electrically connected to the circulation pump.

6. A system for recycling unqualified formaldehyde according to claim 5, characterized in that: A concentration detector is provided in the product storage tank, and the concentration detector is electrically connected to the input end of the controller, and the output end of the controller is electrically connected to the fourth solenoid valve and the fifth solenoid valve respectively.

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