Formaldehyde tail gas treatment system and method

Abstract

The application discloses a formaldehyde tail gas treatment system and method, and belongs to the technical field of formaldehyde tail gas treatment. The system comprises a heat exchanger connected with formaldehyde tail gas, a vacuum pump, a tail gas washing tower and a burning unit. The heat exchanger is communicated with the vacuum pump. The vacuum pump is communicated with the tail gas washing tower through a third pipeline. An air supply pipe is arranged on one side of the tail gas washing tower. A fan is arranged in the air supply pipe. One end of the air supply pipe is connected with the burning unit. A first pipeline is arranged on the lower side of the heat exchanger. One end of the first pipeline is connected with a separation tank. Spraying structures are arranged on the top of the separation tank and the heat exchanger. The separation tank is connected with the vacuum pump through a second pipeline. The second pipeline is a jacketed heat tracing pipeline. Heat exchanger tubes are fixedly arranged in the heat exchanger. A communication seat is arranged on the outer wall of the heat exchanger. The application has the advantages of simple use, simple production process, few production equipment, low investment, a running cycle of the heat exchanger and the pipeline of more than 200 days and high application value.

Description

TECHNICAL FIELD

[0001] The present application relates to a formaldehyde tail gas treatment system and method, belonging to the technical field of formaldehyde tail gas treatment. BACKGROUND

[0002] In the production process of trioxymethylene, during the concentration of 45% formaldehyde into 70% formaldehyde, 15% formaldehyde tail gas is cooled by a heat exchanger, non-condensable gas is transferred to the tail gas washing tower by a vacuum pump, and is sent to a burning unit by a fan for burning and standard emission. In this process, incomplete absorption of formaldehyde tail gas leads to blockage of the heat exchanger and pipeline, damage to the vacuum pump, and greatly reduces the long-period operation of the concentration unit.

[0003] In the Chinese patent with publication number CN113521902A, a flame-retardant formaldehyde tail gas treatment device is proposed, which includes a main absorption chamber, a vice absorption chamber fixedly connected to the bottom of the main absorption chamber, an intermediate filter chamber fixedly installed at the side end of the main absorption chamber, a release port fixedly provided on one side of the intermediate filter chamber, a sealed protection bin fixedly connected to the top of the intermediate filter chamber, a connecting bin movably connected to the upper end of the sealed protection bin, a gas inlet bin fixedly connected to one side of the connecting bin, an observation port fixedly provided on the outer surface of the gas inlet bin, and a fixing frame fixedly connected to the outer surface of the gas inlet bin. The present application provides a formaldehyde tail gas treatment device, which avoids the overflow of excess formaldehyde during the formaldehyde treatment process through the irreversible one-way sealed connection port, pollutes the environment, and improves the safety factor of formaldehyde tail gas treatment and the working efficiency of the formaldehyde tail gas treatment device. The above-mentioned comparative document only improves the sealing effect of the formaldehyde tail gas treatment device, and the recovery of formaldehyde tail gas is still not good enough, and there is room for improvement.

[0004] In the Chinese patent with publication number CN207667371U, a formaldehyde tail gas treatment device is proposed, which uses the design of the first, second and third partitions in the separation tank to separate the exhaust gas, facilitating the reuse of hydrogen gas and avoiding resource waste. The design of the first, second and third vertical plates slows down the gas flow and facilitates gas separation, making the hydrogen recovery rate higher. The design of the bend pipe and the treatment tank can remove toxic gases from the exhaust gas, and the bend pipe will not cause backflow of the chemical treatment liquid, affecting recovery and treatment. The structure is simple, solves the problems of low energy conversion rate and resource waste of the previous formaldehyde tail gas treatment device, has strong practicality, and is easy to popularize. The device proposed in the above-mentioned comparative document mainly recovers hydrogen gas, and the formaldehyde tail gas treatment effect is not good enough. Therefore, the present application is proposed. SUMMARY

[0005] The present application aims at providing a formaldehyde tail gas treatment system and method to solve the above problems, by adding a distributor at the top of the heat exchanger, the heat exchanger coolant continuously sprays the heat exchanger tube, thereby increasing the absorption of formaldehyde tail gas, by adding a separation tank at the lower side of the heat exchanger, the separation tank is also provided with a spray inside, increasing the absorption of formaldehyde tail gas, the pipeline from the top of the separation tank to the vacuum pump inlet is changed to a jacketed heat tracing pipeline, reducing the pipe blockage rate.

[0006] The present application realizes the above-mentioned purposes through the following technical solutions, a formaldehyde tail gas treatment system, comprising a heat exchanger connected to formaldehyde tail gas, a vacuum pump, a tail gas washing tower and a incineration unit, the heat exchanger is communicated with the vacuum pump, the vacuum pump is connected with the tail gas washing tower through a third pipeline, a side of the tail gas washing tower is provided with a air supply pipe, a fan is arranged in the air supply pipe, one end of the air supply pipe is connected with the incineration unit, a first pipeline is arranged at the lower side opening of the heat exchanger, one end of the first pipeline is connected with a separation tank, the separation tank and the top of the heat exchanger are both provided with a spray structure, the separation tank is connected with the vacuum pump through a second pipeline, the second pipeline is a jacketed heat tracing pipeline, a distributor is added at the top of the heat exchanger, the heat exchanger coolant continuously sprays the heat exchanger tube, thereby increasing the absorption of formaldehyde tail gas, a separation tank is added at the lower side opening of the heat exchanger, the separation tank is also provided with a spray inside, increasing the absorption of formaldehyde tail gas, at the same time, the pipeline from the top of the separation tank to the vacuum pump inlet is changed to a jacketed heat tracing pipeline, reducing the pipe blockage rate.

[0007] Preferably, the heat exchanger is fixedly provided with heat exchanger tubes, a communication seat is installed on the outer wall of the heat exchanger, an air inlet hole is arranged on one side of the communication seat for connecting formaldehyde tail gas, one end of each heat exchanger tube is communicated with the communication seat, and the other end of each heat exchanger tube is communicated with the first pipeline, the air inlet hole is connected with formaldehyde tail gas for treatment, and the communication seat disperses the formaldehyde tail gas after being connected to each heat exchanger tube, cooperates with the top spray structure, and keeps the heat exchanger tube in a low temperature state, so that the formaldehyde tail gas passing through is better cooled and the formaldehyde absorption is promoted.

[0008] Preferably, the spray structure arranged on the heat exchanger is a distributor and a spray disc, the spray disc is arranged at the bottom of the distributor, a spray hole is formed in the bottom of the spray disc, the distributor is arranged at the top of the heat exchanger, a water inlet is installed at the top of the distributor, low-temperature heat exchanger coolant is injected through the water inlet, the heat exchanger coolant continuously sprays on the heat exchanger tube for cooling, the heat exchanger tube is kept at a low temperature, and the formaldehyde tail gas is better heat-exchanged and cooled.

[0009] Preferably, the spray structure on the separation tank is specifically a spray plate arranged in the separation tank and a spray opening located at the top of the separation tank, the spray opening is communicated with the spray plate, and in use, the spray liquid is continuously input through the spray opening, the spray liquid is sprayed out after entering the internal sprayer, and the formaldehyde tail gas in the separation tank is subjected to secondary cooling.

[0010] A formaldehyde tail gas treatment method, comprising the following steps:

[0011] S1 heat exchange cooling, formaldehyde tail gas to be treated is input from the air hole at one end of the heat exchanger, is distributed to each heat exchanger tube through the communication seat, and the water injection opening at the top of the distributor continuously inputs the heat exchanger cooling liquid, the heat exchanger cooling liquid is continuously sprayed on the heat exchanger tube, the surface of the heat exchanger tube is kept at low temperature, and the formaldehyde tail gas to be treated is preliminarily cooled through the heat exchanger;

[0012] S2 secondary cooling, the formaldehyde tail gas preliminarily cooled through the heat exchanger enters the separation tank through the first pipeline, the spray liquid is continuously input into the separation tank through the spray opening, the spray liquid is sprayed out after entering the internal sprayer through the spray opening, and the formaldehyde tail gas in the separation tank is subjected to secondary cooling;

[0013] S3 tail gas washing, after the formaldehyde tail gas is subjected to secondary cooling through the separation tank, the formaldehyde tail gas is extracted by opening the vacuum pump, and then is sent into the tail gas washing tower through the third pipeline, and the formaldehyde tail gas is washed in the tail gas washing tower;

[0014] S4 tail gas incineration, after the formaldehyde tail gas is sufficiently washed in the tail gas washing tower, the fan in the air supply pipe is opened, the formaldehyde tail gas is extracted and sent into the incineration unit, the formaldehyde tail gas is incinerated to meet the standard in the incineration unit, and the heat exchanger cooling liquid is specifically a mixed liquid of water and antifreeze.

[0015] The formaldehyde tail gas treatment method has the advantages that the distributor is arranged at the top of the heat exchanger, the heat exchanger cooling liquid continuously sprays on the heat exchanger tube, the absorption of the formaldehyde tail gas is increased, the separation tank is arranged at the lower part of the heat exchanger, the spray is arranged in the separation tank, the absorption of the formaldehyde tail gas is increased, the pipeline from the top of the separation tank to the inlet of the vacuum pump is replaced by the jacketed heat tracing pipeline, the pipeline blockage rate is reduced, the method is simple to use, the production process is simple, the production equipment is few, the investment is less, the running cycle of the heat exchanger and the pipeline is more than 200 days, and the method has high application value. BRIEF DESCRIPTION OF DRAWINGS

[0016] Figure 1 It is a whole structure schematic view of the system equipment of the present application.

[0017] Figure 2It is the overall structure schematic diagram of left side view angle of the system equipment of the application.

[0018] Figure 3 It is the internal structure schematic diagram of the heat exchanger in the application.

[0019] Figure 4 It is the internal structure schematic diagram of the heat exchanger under the upward angle in the application.

[0020] Figure 5 It is the process flow chart of the method of the application.

[0021] In the figure: 1, heat exchanger; 101, heat exchanger tube; 102, communication seat; 103, air hole; 104, distributor; 105, spray tray; 106, spray hole; 107, water injection port; 2, separation tank; 201, spray port; 3, vacuum pump; 4, tail gas washing tower; 5, incineration unit; 6, first pipeline; 7, second pipeline; 8, third pipeline; 9, air supply pipe. DETAILED DESCRIPTION

[0022] The technical solutions in the embodiments of the application will be clearly and completely described below with reference to the drawings in the embodiments of the application. Obviously, the described embodiments are only part of the embodiments of the application, rather than all the embodiments of the application. Based on the embodiments in the application, all other embodiments obtained by those skilled in the art without creative labor fall within the protection scope of the application.

[0023] Please refer to Figures 1-5 as shown.

[0024] Embodiment 1

[0025] A formaldehyde tail gas treatment system, comprising a heat exchanger 1 connected to formaldehyde tail gas, a vacuum pump 3, a tail gas washing tower 4 and an incineration unit 5, the heat exchanger 1 is communicated with the vacuum pump 3, the vacuum pump 3 is communicated with the tail gas washing tower 4 through the third pipeline 8, one side of the tail gas washing tower 4 is provided with an air supply pipe 9, a fan is arranged in the air supply pipe 9, one end of the air supply pipe 9 is connected with the incineration unit 5, the lower side of the heat exchanger 1 is provided with a first pipeline 6, one end of the first pipeline 6 is connected with a separation tank 2, the separation tank 2 and the top of the heat exchanger 1 are both provided with a spray structure, the separation tank 2 is connected with the vacuum pump 3 through a second pipeline 7, and the second pipeline 7 is a jacketed heat tracing pipeline.

[0026] In the application, the heat exchanger 1, the vacuum pump 3, the tail gas washing tower 4 and the incineration unit 5 are the commonly used equipment for the current formaldehyde tail gas treatment, the formaldehyde tail gas is cooled through the heat exchanger 1, the non-condensable gas is transferred to the tail gas washing tower 4 through the vacuum pump 3, is sent to the incineration unit 5 through the fan and is incinerated to reach the standard discharge, on the basis, the application increases the distributor 104 at the top of the heat exchanger 1, the heat exchanger coolant continuously sprays the heat exchanger tube 101, thereby increasing the absorption of the formaldehyde tail gas, on the other hand, the heat exchanger 1 lower side opening increases the separation tank 2, the inside of the separation tank 2 is also provided with spraying, increases the absorption of the formaldehyde tail gas, at the same time, the separation tank 2 top to the vacuum pump 3 inlet pipeline is changed into the jacketed heat tracing pipeline, reduces the pipeline blockage rate, compared with the prior art, the application is simple and convenient to use, the production process is simple, the production equipment is little, the investment is less, the heat exchanger 1 and the pipeline operation cycle reach more than 200 days, has higher application value.

[0027] As shown in Figure 3 The heat exchanger 1 is fixedly provided with the heat exchanger tube 101, the outer wall of the heat exchanger 1 is provided with the communication seat 102, one side of the communication seat 102 is provided with the air hole 103 for the formaldehyde tail gas access, one end of each of the heat exchanger tubes 101 is communicated with the communication seat 102, the other end of each of the heat exchanger tubes 101 is communicated with the first pipeline 6, the air hole 103 accesses the formaldehyde tail gas for treatment, the communication seat 102 disperses the formaldehyde tail gas after access to each heat exchanger tube 101, cooperates with the top spraying structure, keeps the heat exchanger tube 101 low temperature state, thereby making the passing formaldehyde tail gas be better cooled, promoting the formaldehyde absorption.

[0028] Example 2

[0029] A formaldehyde tail gas treatment system, including the heat exchanger 1 of access formaldehyde tail gas, vacuum pump 3, tail gas washing tower 4 and incineration unit 5, the heat exchanger 1 with the vacuum pump 3 is communicated, the vacuum pump 3 is communicated with the tail gas washing tower 4 through the third pipeline 8, one side of the tail gas washing tower 4 is installed with the air supply pipe 9, the air supply pipe 9 is provided with the fan, one end of the air supply pipe 9 is connected with the incineration unit 5, the lower side opening of the heat exchanger 1 is provided with the first pipeline 6, one end of the first pipeline 6 is connected with the separation tank 2, the separation tank 2 and the top of the heat exchanger 1 are provided with the spraying structure, the separation tank 2 is connected with the vacuum pump 3 through the second pipeline 7, the second pipeline 7 is the jacketed heat tracing pipeline.

[0030] The application further limits the spraying structure provided on the heat exchanger 1 based on example 1, and specifically as Figure 4As shown, the spray structure provided on the heat exchanger 1 is specifically a distributor 104 and a spray plate 105, the spray plate 105 is provided at the bottom of the distributor 104, the bottom of the spray plate 105 is provided with spray holes 106, the distributor 104 is provided at the top of the heat exchanger 1, and a water inlet 107 is installed at the top of the distributor 104. The low-temperature heat exchanger cooling liquid is injected through the water inlet 107, so that the heat exchanger cooling liquid continuously sprays on the heat exchanger tube 101 for cooling, so that the heat exchanger tube 101 remains low temperature, and the formaldehyde tail gas is better heat-exchanged and cooled.

[0031] Embodiment 3

[0032] A formaldehyde tail gas treatment system, comprising a heat exchanger 1 connected to the formaldehyde tail gas, a vacuum pump 3, a tail gas washing tower 4 and a incineration unit 5, the heat exchanger 1 is communicated with the vacuum pump 3, the vacuum pump 3 is connected with the tail gas washing tower 4 through a third pipeline 8, a side of the tail gas washing tower 4 is provided with a air supply pipe 9, a fan is arranged in the air supply pipe 9, one end of the air supply pipe 9 is connected with the incineration unit 5, a first pipeline 6 is arranged at the lower side of the heat exchanger 1, one end of the first pipeline 6 is connected with a separation tank 2, the separation tank 2 and the top of the heat exchanger 1 are provided with a spray structure, the separation tank 2 is connected with the vacuum pump 3 through a second pipeline 7, and the second pipeline 7 is a jacketed heat tracing pipeline.

[0033] The embodiment is based on the spray structure on the separation tank 2 in embodiment 1, and the spray structure on the separation tank 2 is specifically a spray plate arranged in the separation tank 2 and a spray port 201 located at the top of the separation tank 2. The spray port 201 is communicated with the spray plate. In use, the spray liquid is continuously input through the spray port 201, the spray liquid is sprayed out after entering the internal sprayer, and the formaldehyde tail gas in the separation tank 2 is secondarily cooled.

[0034] A formaldehyde tail gas treatment method, comprising the following steps:

[0035] S1 heat exchange and cooling, the formaldehyde tail gas to be treated is introduced from the air hole 103 at one end of the heat exchanger 1, and is distributed to each heat exchanger tube 101 through the communication seat 102, while the water inlet 107 at the top of the distributor 104 continuously inputs the heat exchanger cooling liquid, the heat exchanger cooling liquid continuously sprays on the heat exchanger tube 101, so that the surface of the heat exchanger tube 101 remains low temperature, and the formaldehyde tail gas to be treated is preliminarily cooled through the heat exchanger 1.

[0036] S2 secondary cooling, the formaldehyde tail gas after preliminary cooling by the heat exchanger 1 enters the separation tank 2 through the first pipeline 6, the separation tank 2 continuously inputs spray liquid through the spray port 201, the spray liquid is sprayed out after entering the internal sprayer through the spray port 201, and the formaldehyde tail gas in the separation tank 2 is secondarily cooled.

[0037] S3 tail gas washing, the formaldehyde tail gas after secondary cooling in the separation tank 2 is extracted by opening the vacuum pump 3, and then is sent into the tail gas washing tower 4 through the third pipeline 8, and the formaldehyde tail gas is washed in the tail gas washing tower 4.

[0038] S4 tail gas incineration, after the formaldehyde tail gas is sufficiently washed in the tail gas washing tower 4, the fan in the air supply pipe 9 is opened, the formaldehyde tail gas is extracted and sent into the incineration unit 5, the formaldehyde tail gas is incinerated to reach the standard in the incineration unit 5, and the heat exchanger cooling liquid is a mixed liquid of water and antifreeze.

[0039] It is apparent for those skilled in the art that the present application is not limited to the details of the above exemplary embodiments, but can be implemented in other concrete forms without departing from the spirit or essential characteristics of the present application. Therefore, the embodiments should be considered as exemplary and non-limiting, and the scope of the present application is defined by the appended claims rather than the above description, and all changes falling within the meaning and range of the equivalent elements of the claims are intended to be embraced in the present application. Any reference signs in the claims should not be considered as limiting the claims involved.

[0040] In addition, it should be understood that although the present specification is described in terms of embodiments, not every embodiment contains only one independent technical solution, and the description of the specification is only for the sake of clarity, and those skilled in the art should consider the specification as a whole, and the technical solutions in each embodiment can be appropriately combined to form other embodiments that those skilled in the art can understand.

Claims

1. A formaldehyde exhaust gas treatment system, comprising a heat exchanger (1) for receiving formaldehyde exhaust gas, a vacuum pump (3), an exhaust gas scrubbing tower (4), and an incineration unit (5), wherein the heat exchanger (1) is connected to the vacuum pump (3), the vacuum pump (3) is connected to the exhaust gas scrubbing tower (4) via a third pipe (8), an air supply pipe (9) is installed on one side of the exhaust gas scrubbing tower (4), a fan is installed inside the air supply pipe (9), and one end of the air supply pipe (9) is connected to the incineration unit (5), characterized in that: The heat exchanger (1) has a first pipe (6) with an opening on the lower side. One end of the first pipe (6) is connected to the separation tank (2). Both the separation tank (2) and the heat exchanger (1) have a spray structure on their tops. The separation tank (2) is connected to the vacuum pump (3) through a second pipe (7), which is a jacketed heat tracing pipeline.

2. The formaldehyde exhaust gas treatment system according to claim 1, characterized in that: The heat exchanger (1) is fixedly provided with heat exchanger tubes (101), and a connecting seat (102) is installed on the outer wall of the heat exchanger (1).

3. The formaldehyde exhaust gas treatment system according to claim 2, characterized in that: A vent hole (103) is provided on one side of the connecting seat (102) for formaldehyde exhaust gas to enter. One end of each heat exchanger tube (101) is connected to the connecting seat (102), and the other end of each heat exchanger tube (101) is connected to the first pipe (6).

4. The formaldehyde exhaust gas treatment system according to claim 3, characterized in that: The spray structure provided on the heat exchanger (1) is specifically a distributor (104) and a spray plate (105). The spray plate (105) is located at the bottom of the distributor (104), and a spray hole (106) is provided at the bottom of the spray plate (105).

5. The formaldehyde exhaust gas treatment system according to claim 4, characterized in that: The distributor (104) is located on the top of the heat exchanger (1), and a water inlet (107) is installed on the top of the distributor (104).

6. The formaldehyde exhaust gas treatment system according to claim 1, characterized in that: The spray structure on the separation tank (2) specifically consists of a spray plate installed inside the separation tank (2) and a spray nozzle (201) located at the top of the separation tank (2), with the spray nozzle (201) connected to the spray plate.

7. A method for treating formaldehyde exhaust gas, characterized in that, Includes the following steps: S1 heat exchange cooling: The formaldehyde exhaust gas to be treated is introduced into the heat exchanger through the vent at one end of the heat exchanger and distributed to each heat exchanger tube through the connecting seat. At the same time, the water inlet at the top of the distributor continuously introduces the heat exchanger coolant, which is continuously sprayed onto the heat exchanger tube, keeping the surface of the heat exchanger tube at a low temperature. The formaldehyde exhaust gas to be treated is initially cooled by the heat exchanger. S2 secondary cooling: After the formaldehyde exhaust gas is initially cooled by the heat exchanger, it enters the separation tank through the first pipe. Spray liquid is continuously fed into the separation tank through the spray nozzle, and the spray liquid enters the internal sprayer through the spray nozzle and is sprayed out to perform secondary cooling on the formaldehyde exhaust gas in the separation tank. S3 exhaust gas scrubbing: After the formaldehyde exhaust gas is cooled twice in the separator, it is extracted by turning on the vacuum pump and then sent into the exhaust gas scrubbing tower through the third pipeline to scrub the formaldehyde exhaust gas. In S4 exhaust gas incineration, after the formaldehyde exhaust gas is thoroughly washed in the exhaust gas scrubbing tower, the fan in the air supply duct is turned on to extract the formaldehyde exhaust gas and send it into the incineration unit. The formaldehyde exhaust gas is then incinerated in the incineration unit to meet the standards before being discharged.

8. A method for treating formaldehyde exhaust gas, according to claim 7, characterized in that, The heat exchanger coolant is specifically a mixture of water and antifreeze.

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