Formaldehyde tail gas treatment device

Abstract

The utility model relates to the technical field of formaldehyde production discloses a kind of formaldehyde tail gas treatment device, including the hearth that is sequentially communicated in horizontal direction, the heat exchange section for generating steam for primary heat exchange and the tail gas cooling section for secondary heat exchange further recovery waste heat, the gas inlet end of the hearth is connected with the tail gas pipeline for passing into tail gas and the combustion-supporting pipeline for passing into combustion-supporting gas, the gas outlet end of hearth and the gas inlet end of heat exchange section are communicated, the gas outlet end of heat exchange section and the gas inlet end of the tail gas cooling section are communicated, the gas outlet end of tail gas cooling section is connected by pipeline connection induced draft fan, heat exchange section and tail gas cooling section are connected with the heat exchange pipeline system for circulating heat exchange medium, the heat energy cascade utilization of the device, tail gas calorific value is efficiently recovered, energy utilization rate is high, part is converted into high-grade steam, another part is used for preheating feed water, reduce the energy consumption of system itself.

Description

Technical Field

[0001] This utility model relates to the technical field of formaldehyde production, specifically to a formaldehyde exhaust gas treatment device. Background Technology

[0002] During formaldehyde production, approximately 600 cubic meters of exhaust gas (37%) is generated for every ton of formaldehyde produced, with a calorific value of around 1970 kJ / mol. This exhaust gas contains components such as hydrogen, carbon monoxide, methane, carbon dioxide, nitrogen, and a small amount of water. The combustible gases, including hydrogen and carbon monoxide, have a certain calorific value and could be utilized as clean energy.

[0003] In existing technologies, such as the formaldehyde exhaust gas treatment system disclosed in CN213901093U, there are exhaust gas heating towers, flues, economizers, and chimneys connected in sequence. An air inlet is located at the end of the exhaust gas heating tower furthest from the flue, and exhaust gas inlet pipes, air inlet pipes, and fuel gas inlet pipes are connected to the air inlet. A steam outlet pipe is installed on the exhaust gas heating tower, and a water inlet pipe is connected to the economizer. However, this system only has a single heat exchange stage, resulting in limited efficiency of the heat recovery system, low energy utilization, and insufficient stability and safety during operation. Summary of the Invention

[0004] Therefore, the purpose of this utility model is to provide a formaldehyde exhaust gas treatment device that can effectively solve the problems mentioned in the background art.

[0005] This utility model adopts the following technical solution: a formaldehyde exhaust gas treatment device, comprising a furnace, a heat exchange section for primary heat exchange and steam generation, and an exhaust gas cooling section for secondary heat exchange and further recovery of waste heat, arranged sequentially in a horizontal direction. The inlet end of the furnace is connected to an exhaust gas pipe for introducing exhaust gas and an auxiliary combustion gas pipe for introducing combustion gas. The outlet end of the furnace is connected to the inlet end of the heat exchange section, and the outlet end of the heat exchange section is connected to the inlet end of the exhaust gas cooling section. The outlet end of the exhaust gas cooling section is connected to an induced draft fan through a pipe. Both the heat exchange section and the exhaust gas cooling section are connected to a heat exchange pipe system for circulating heat exchange medium.

[0006] The exhaust gas cooling section is equipped with a heat exchange pipe.

[0007] The heat exchange section is equipped with a second heat exchange pipe, and a steam drum structure for storing and separating the generated steam is connected above the second heat exchange pipe.

[0008] The water injection pipe is preferentially connected to the inlet of the heat exchange pipe in the exhaust gas cooling section, and the outlet of the heat exchange pipe extends to the inlet of the heat exchange pipe in the heat exchange section, forming a two-stage countercurrent heat exchange path.

[0009] The combustion-supporting pipeline has an oxygen channel and a gas port for introducing coal gas connected in parallel at its input end, and a valve is provided on the gas port.

[0010] The furnace is equipped with an observation window.

[0011] The steam drum structure is connected to a steam pipeline to output steam.

[0012] A drain outlet is provided at the lower part of the heat exchange section, and a level gauge for detecting and displaying the liquid level inside the container is provided on the outside of the heat exchange section.

[0013] The exhaust gas cooling section has a conical outlet, and the outlet of the induced draft fan is connected to an exhaust tower.

[0014] The furnace, heat exchange section, and exhaust gas cooling section are connected by flanges or welded to form a continuous integral structure.

[0015] Compared with the prior art, the advantages of this utility model are as follows: the device utilizes thermal energy in a cascade manner, efficiently recovers the calorific value of the exhaust gas, has a high energy utilization rate, converts part of it into high-grade steam, and uses the other part to preheat feedwater, reducing the energy consumption of the system itself. The combustible components in the exhaust gas are burned and decomposed, and the final emission is clean flue gas mainly composed of CO2 and H2O, which is environmentally friendly and pollution-free. The backup gas design ensures that the device can operate stably under various working conditions and has strong anti-interference ability. Attached Figure Description

[0016] Figure 1 This is a schematic diagram of the structure of this utility model; Figure 2 This is a schematic diagram of the internal structure of the heat exchange section and the exhaust gas cooling section of this utility model; In the diagram: 1. Furnace; 2. Heat exchange section; 3. Tail gas cooling section; 4. Blower; 5. Gas port; 6. Valve; 7. Combustion-supporting pipe; 8. Steam pipe; 9. Water injection pipe; 10. Induced draft fan; 11. Exhaust tower; 12. Observation window; 13. Level gauge; 14. Tail gas pipe; 15. Heat exchange pipe one; 16. Heat exchange pipe two; 17. Steam drum; 18. Drain outlet. Detailed Implementation

[0017] It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other. The present invention will now be described in detail with reference to the accompanying drawings and embodiments.

[0018] To enable those skilled in the art to better understand the present application, the technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present application, and not all embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative effort should fall within the scope of protection of the present application.

[0019] Please see Figure 1 , Figure 2 As shown, a formaldehyde exhaust gas treatment device includes a furnace 1, a heat exchange section 2 for primary heat exchange and steam generation, and an exhaust gas cooling section 3 for secondary heat exchange and further waste heat recovery, arranged sequentially in a horizontal direction. The inlet end of the furnace 1 is connected to an exhaust gas pipe 14 for introducing exhaust gas and a combustion-supporting gas pipe 7 for introducing combustion-supporting gas. The outlet end of the furnace 1 is connected to the inlet end of the heat exchange section 2, and the outlet end of the heat exchange section 2 is connected to the inlet end of the exhaust gas cooling section 3. The outlet end of the exhaust gas cooling section 3 is connected to an induced draft fan 10 through a pipe. Both the heat exchange section 2 and the exhaust gas cooling section 3 are connected to a heat exchange pipe system for circulating heat exchange medium.

[0020] The exhaust gas cooling section 3 is equipped with a heat exchange pipe 15.

[0021] The heat exchange section 2 is provided with a heat exchange pipe 2 16 inside, and a steam drum structure 17 for storing and separating the generated steam is connected above the heat exchange pipe 2 16.

[0022] The water injection pipe 9 is preferentially connected to the inlet of the heat exchange pipe 15 of the exhaust gas cooling section 3, and the outlet of the heat exchange pipe 15 extends to the inlet of the heat exchange pipe 16 of the heat exchange section 2, forming a two-stage countercurrent heat exchange path.

[0023] The combustion-supporting pipeline 7 has an oxygen channel and a gas port 5 for introducing coal gas connected in parallel at its input end. A valve 6 is provided on the gas port 5.

[0024] The furnace 1 is equipped with an observation window 12 and a detector for monitoring the combustion status. The detector is connected to the central control room for real-time monitoring of the internal combustion situation.

[0025] The steam drum structure 17 outputs steam through the steam pipe 8.

[0026] The lower part of the heat exchange section 2 is provided with a drain outlet 18, and the outside of the heat exchange section 2 is provided with a level gauge 13 for detecting and displaying the liquid level in the container.

[0027] The exhaust gas cooling section 3 has a conical structure at its outlet, and the exhaust tower 11 is connected to the outlet of the induced draft fan 10.

[0028] The furnace chamber 1, heat exchange section 2, and exhaust gas cooling section 3 are connected by flanges or welded to form a continuous integral structure.

[0029] The combustion-supporting pipe 7, steam pipe 8, water injection pipe 9, and drain outlet 18 are equipped with corresponding control valve groups.

[0030] This invention integrates a SIS safety instrumented system, which is independent of the basic process control system and focuses on safety protection.

[0031] One embodiment of this utility model: The blower supplies oxygen and coal gas through the combustion-supporting pipe 7. The methanol gas, formaldehyde gas and ammonia gas introduced through the tail gas pipe 14 are fully mixed by the mixer and then burned. A flame detector is installed in the furnace 1 and connected to the central control room. When the system starts up or the calorific value of the tail gas is unstable, the coal gas is used to assist combustion to generate steam to ensure successful ignition and stable combustion. After normal operation, the valve 6 is closed to stop the coal gas injection. At this time, the tail gas burns normally. The operator can monitor the flame status through the observation window 12 and the detector. In the first stage of heat exchange, the high-temperature flue gas generated by combustion flows into heat exchange section 2 and washes the heat exchange pipe 16. At this time, the heat exchange pipe 16 contains hot water that has been preheated after heat exchange in heat exchange pipe 15. The high-temperature flue gas heats it to saturation temperature, producing a steam-water mixture. The steam-water mixture rises into the steam drum 17, where steam-water separation takes place. The separated saturated steam is output through steam pipe 8 and can be used for production or domestic purposes. The separated water continues to circulate or is discharged through the drain outlet. In the second stage of heat exchange, the cooled flue gas enters the tail gas cooling section 3, flushing the heat exchange pipe 15. The ambient temperature boiler feedwater injected by the water injection pipe 9 first enters the heat exchange pipe 15 and exchanges heat with the flue gas in a countercurrent manner, absorbing the residual heat in the flue gas. The water temperature is preheated to above 90°C, and the flue gas temperature is further reduced to about 120-150°C. The cooled low temperature flue gas is discharged through the conical outlet under the suction action of the induced draft fan 10, and finally discharged into the atmosphere through the exhaust tower 11.

[0032] The above description is merely a preferred embodiment of this utility model and is not intended to limit the utility model. Various modifications and variations can be made to this utility model by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this utility model should be included within the protection scope of this utility model.

Claims

1. A formaldehyde exhaust gas treatment device, characterized in that: The furnace includes a furnace (1) arranged in a horizontal direction, a heat exchange section (2) for primary heat exchange and steam generation, and a tail gas cooling section (3) for secondary heat exchange and further recovery of waste heat. The furnace (1) is connected to a tail gas pipe (14) for introducing tail gas and a combustion-supporting pipe (7) for introducing combustion-supporting gas. The furnace (1) is connected to the heat exchange section (2) at the air inlet and to the tail gas cooling section (3) at the air inlet. The tail gas cooling section (3) is connected to an induced draft fan (10) through a pipe at the air outlet. Both the heat exchange section (2) and the tail gas cooling section (3) are connected to a heat exchange pipe system for circulating heat exchange medium.

2. The formaldehyde exhaust gas treatment device according to claim 1, characterized in that: The exhaust gas cooling section (3) is equipped with a heat exchange pipe (15).

3. The formaldehyde exhaust gas treatment device according to claim 1, characterized in that: The heat exchange section (2) is provided with a second heat exchange pipe (16) inside, and a steam drum structure (17) for storing and separating the generated steam is connected above the second heat exchange pipe (16).

4. The formaldehyde exhaust gas treatment device according to claim 1, characterized in that: The exhaust gas cooling section (3) is equipped with a heat exchange pipe 1 (15), and the heat exchange section (2) is equipped with a heat exchange pipe 2 (16). A steam drum structure (17) for storing and separating the generated steam is connected above the heat exchange pipe 2 (16). The water injection pipe (9) is preferentially connected to the inlet of the heat exchange pipe 1 (15) of the exhaust gas cooling section (3), and the outlet of the heat exchange pipe 1 (15) extends to the inlet of the heat exchange pipe 2 (16) of the heat exchange section (2), forming a two-stage countercurrent heat exchange path.

5. The formaldehyde exhaust gas treatment device according to claim 1, characterized in that: The combustion-supporting pipe (7) has an oxygen channel and a gas port (5) for introducing coal gas connected in parallel at its input end. A valve (6) is provided on the gas port (5).

6. The formaldehyde exhaust gas treatment device according to claim 1, characterized in that: The furnace (1) is equipped with an observation window (12).

7. The formaldehyde exhaust gas treatment device according to claim 3, characterized in that: The steam drum structure (17) is connected to the steam pipe (8) to output steam.

8. The formaldehyde exhaust gas treatment device according to claim 1, characterized in that: The lower part of the heat exchange section (2) is provided with a drain outlet (18), and the outside of the heat exchange section (2) is provided with a level gauge (13) for detecting and displaying the liquid level in the container.

9. The formaldehyde exhaust gas treatment device according to claim 1, characterized in that: The exhaust gas cooling section (3) has a conical structure at its outlet, and the exhaust tower (11) is connected to the outlet of the induced draft fan (10).

10. A formaldehyde exhaust gas treatment device according to claim 1, characterized in that: The furnace (1), heat exchange section (2) and exhaust gas cooling section (3) are connected by flanges or welded to form a continuous integral structure.

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