A VOCs waste gas treatment device based on secondary waste heat recovery

Abstract

The present invention relates to a VOCs waste gas treatment device based on secondary waste heat recovery. The device is composed of a waste gas storage chamber, an exhaust chimney, a preheating box, and a heating catalyst box connected by pipes. The preheating box is equipped with three one-way airflow heat exchangers with the same structure and arranged in an inclined shape and connected end to end. The upper layer of the heating catalyst box has a heat exchange chamber, a heating chamber, and a catalyst chamber from right to left. Two one-way airflow heat exchangers are arranged side by side in the heat exchange chamber. An electric heating wire is installed in the heating chamber. A precious metal honeycomb ceramic catalyst is installed in the catalyst chamber. The VOCs waste gas in the present invention passes through the one-way airflow heat exchanger twice, is heated in the heating chamber, and then enters the catalyst chamber. The precious metal honeycomb ceramic catalyst catalyzes the reaction and converts it into carbon dioxide and water. The waste heat gas after the reaction then passes through the one-way airflow heat exchanger in the opposite direction to recover waste heat twice, storing heat for the primary and secondary heating of the next waste gas, thereby improving energy utilization efficiency and reducing energy usage.

Description

Technical Field

[0001] The present invention relates to the technical field of waste gas treatment, and in particular to a VOCs waste gas treatment device based on secondary waste heat recovery. Background Art

[0002] Volatile organic compounds (VOCs) are primarily composed of hydrocarbons, oxygen-containing organic compounds, and organic compounds containing chlorine, sulfur, phosphorus, and halogens. These harmful organic volatiles, if released directly into the atmosphere without treatment, can cause serious environmental pollution. Existing methods for treating VOC waste gas include catalytic combustion, activated carbon adsorption, low-temperature plasma, and ultraviolet light irradiation. The most ideal treatment method involves heating the VOC waste gas to above 800°C in a furnace, either through self-combustion or with the aid of a burner, to decompose it into carbon dioxide and water, which are then released into the atmosphere.

[0003] Waste heat recovery is based on fully utilizing the heat of the gases after the catalytic reaction, minimizing energy loss and maximizing utilization efficiency. This recovered heat is then used for heating in the next process, reducing electricity usage. This reduces energy consumption while treating waste gas, fully implementing environmental protection. Currently, waste heat recovery from VOCs waste gas treatment generally uses a primary heat recovery system. Most of the waste heat recovery equipment used is a finned heat exchanger, which has a high wind resistance and affects heat exchange efficiency. Summary of the Invention

[0004] The technical problem to be solved by the present invention is: in order to overcome the deficiencies in the existing technology, the present invention provides a VOCs waste gas treatment device based on secondary waste heat recovery. Based on the excellent catalytic performance of the precious metal honeycomb ceramic catalyst, harmful VOCs gases are converted into harmless carbon dioxide and water. At the same time, the secondary waste heat of the gas after the reaction is recovered to improve energy utilization.

[0005] The technical solution adopted by the present invention to solve the technical problem is: a VOCs waste gas treatment device based on secondary waste heat recovery, comprising:

[0006] The preheating box has an air inlet end for the waste gas to be treated. The preheating box is provided with three one-way airflow heat exchangers of the same structure. The three one-way airflow heat exchangers are arranged in an inclined shape and connected end to end to divide the preheating box into eight closed triangular prism cavities.

[0007] The heating catalytic box has a double-layer structure inside. The upper layer has a heat exchange chamber, a heating chamber and a catalytic chamber from right to left. The right air inlet end of the heating catalytic box is connected to the right air outlet end of the preheating box through a pipeline to pass the preheated gas into the heat exchange chamber. The heat exchange chamber and the heating chamber, as well as the heating chamber and the catalytic chamber, are connected or closed respectively by movable baffle brackets.

[0008] Two one-way airflow heat exchangers are arranged side by side in the heat exchange cavity, wherein an upper baffle is fixedly connected between the right side of the one-way airflow heat exchanger and the upper inner wall of the heating catalyst box, an electric heating wire is installed in the heating cavity, and a precious metal honeycomb ceramic catalyst is arranged in the catalyst cavity;

[0009] A high-temperature gas pipe connected to the catalytic chamber is provided in the lower layer of the heating catalytic box. Two lower baffles are fixed at a distance in the lower layer of the heating catalytic box below the heat exchange chamber. The two lower baffles are respectively located below the right side of the two unidirectional airflow heat exchangers. A preheating return air pipe is connected between the heating catalytic box and the preheating box between the two lower baffles.

[0010] Furthermore, the left side of the preheating box is respectively connected to an air intake duct and an exhaust duct, wherein the air intake duct is connected to the triangular prism cavity at the upper left corner of the preheating box, and the exhaust duct is connected to the triangular prism cavity at the lower left corner of the preheating box. The air intake duct is connected to an exhaust gas storage chamber, and the exhaust duct is connected to an exhaust chimney.

[0011] Specifically, the one-way airflow heat exchanger includes a heat exchange box body, in which mutually perpendicular one-way air inlet ducts and one-way exhaust ducts are provided. The gas introduced into the one-way air inlet duct of the previous one-way airflow heat exchanger enters the one-way air inlet duct of the next one-way airflow heat exchanger, and the gas discharged from the one-way exhaust duct of the previous one-way airflow heat exchanger enters the one-way exhaust duct of the next one-way airflow heat exchanger.

[0012] Preferably, the three one-way airflow heat exchangers in the preheating box are arranged at an angle of 45°.

[0013] Furthermore, the baffle bracket is pushed and moved by a movable hinge to achieve communication or closure between the heat exchange chamber and the heating chamber, and between the heating chamber and the catalytic chamber.

[0014] The beneficial effects of the present invention are as follows: the VOCs waste gas in the present invention passes through the one-way airflow heat exchanger twice, is heated in the heating chamber, and then enters the catalytic chamber, where it is catalytically reacted with the precious metal honeycomb ceramic catalyst to be converted into harmless carbon dioxide and water; then the waste heat gas with a higher temperature after the reaction passes through the one-way airflow heat exchanger in the reverse direction again to recover the waste heat twice, and the stored heat is used for the primary and secondary heating of the waste gas in the next process, thereby maximizing the energy utilization efficiency and reducing energy usage. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] The present invention will be further described below with reference to the accompanying drawings and examples.

[0016] Figure 1 It is a structural schematic diagram of the present invention.

[0017] Figure 2 It is a schematic diagram of the installation of the one-way airflow heat exchanger in the preheating box of the present invention.

[0018] Figure 3 It is a schematic diagram of the installation of the one-way airflow heat exchanger in the heat exchange cavity of the present invention.

[0019] In the figure: 1. Exhaust gas storage chamber, 2. Exhaust chimney, 3. Preheating box, 3-1. Triangular prism cavity, 4. Heating catalyst box, 4-1. Heat exchange chamber, 4-2. Heating chamber, 4-3. Catalytic chamber, 5. Air intake duct, 6. Blower, 7. Exhaust duct, 8. One-way air flow heat exchanger, 8-1. Heat exchange box body, 8-2. One-way air intake duct 8-3. One-way exhaust duct, 9. Baffle bracket, 10. Movable hinge, 11. Upper baffle, 12. Heating wire, 13. Precious metal honeycomb ceramic catalyst, 14. Lower baffle, 15. Preheating return air pipe. DETAILED DESCRIPTION

[0020] The present invention will now be described in further detail with reference to the accompanying drawings, which are simplified schematic diagrams that illustrate the basic structure of the present invention in a schematic manner.

[0021] like Figure 1 The VOCs waste gas treatment device based on secondary waste heat recovery shown is composed of a waste gas storage chamber 1, an emission chimney 2, a preheating box 3 and a heating catalyst box 4 connected by pipes.

[0022] The waste gas storage chamber 1 stores VOCs waste gas to be treated. The waste gas storage chamber 1 is connected to the air inlet at the upper end of the left side surface of the preheating box 3 through the air inlet pipe 5, and the waste gas is blown into the preheating box 3 through the blower 6; the exhaust port of the preheating box 3 is located at the lower end of its left side and is connected to the exhaust chimney 4 through the exhaust pipe 7. The treated gas is drawn out to the exhaust chimney 4 through the blower 6 and discharged into the atmosphere.

[0023] like Figure 1 、 Figure 2 As shown, three unidirectional airflow heat exchangers 8 with the same structure are provided in the preheating box 3. The three unidirectional airflow heat exchangers 8 are arranged at an angle of 45 degrees and connected end to end to divide the preheating box 3 into eight closed triangular prism cavities 3-1. The eight triangular prism cavities 3-1 are arranged in groups of two along the length direction of the preheating box 3. The two triangular prism cavities 3-1 in each group are distributed up and down. The air intake duct 5 is connected to the triangular prism cavities 3-1 above the first group on the left side of the preheating box 3, and the exhaust duct 7 is connected to the triangular prism cavities 3-1 below the first group on the left side of the preheating box 3.

[0024] The one-way airflow heat exchanger 8 includes a heat exchange box body 8-1, and the heat exchange box body 8-1 is provided with a one-way air inlet duct 8-2 and a one-way exhaust duct 8-3 which are perpendicular to each other. The gas introduced into the one-way air inlet duct 8-2 of the previous one-way airflow heat exchanger 8 enters the one-way air inlet duct 8-2 of the next one-way airflow heat exchanger 8, and the gas discharged from the one-way exhaust duct 8-3 of the previous one-way airflow heat exchanger 8 enters the one-way exhaust duct 8-3 of the next one-way airflow heat exchanger 8.

[0025] The one-way air inlet duct 8-2 of the first one-way airflow heat exchanger 8 in the preheating box 3 runs from the upper left to the lower right of the heat exchange box body 8-1, and the one-way exhaust duct 8-3 runs from the upper right to the lower left of the heat exchange box body 8-1. The one-way air inlet duct 8-2 of the second one-way airflow heat exchanger 8 runs from the lower left to the upper right of the heat exchange box body 8-1, and the one-way exhaust duct 8-3 runs from the lower right to the upper left. The one-way air inlet duct 8-2 of the third one-way airflow heat exchanger 8 runs from the upper left to the lower right of the heat exchange box body 8-1, and the one-way exhaust duct 8-3 runs from the upper right to the lower left.

[0026] like Figure 1 、 Figure 3 As shown, the interior of the heating and catalytic box 4 has a double-layer structure. The upper layer of the heating and catalytic box 4 is composed of a heat exchange chamber 4-1, a heating chamber 4-2, and a catalytic chamber 4-3 from right to left. A movable baffle bracket 9 is provided between the heat exchange chamber 4-1 and the heating chamber 4-2, and between the heating chamber 4-2 and the catalytic chamber 4-3. The baffle bracket 9 is moved by a movable hinge 10 to connect or block the heat exchange chamber 4-1 and the heating chamber 4-2, and between the heating chamber 4-2 and the catalytic chamber 4-3. The air inlet on the right side of the heating and catalytic box 4 is connected to the air outlet on the right side of the preheating box 3, thereby passing the preheated gas into the heat exchange chamber 4-1.

[0027] Two one-way airflow heat exchangers 8 with the same structure as those in the preheating box 3 are arranged side by side in the heat exchange chamber 4-1. The one-way air inlet ducts 8-2 of the two one-way airflow heat exchangers 8 are horizontally connected. The one-way air exhaust duct 8-3 of the one-way airflow heat exchanger 8 on the right side is vertically downward, and the one-way air exhaust duct 8-3 of the one-way airflow heat exchanger 8 on the left side is vertically upward.

[0028] An upper baffle 11 is fixedly connected between the upper right end of the one-way airflow heat exchanger 8 on the right and the upper inner wall of the heating catalyst box 4. A heating wire 12 is installed in the heating chamber 4-2, and a precious metal honeycomb ceramic catalyst 13 is provided in the catalyst chamber 4-3.

[0029] A high-temperature gas pipe 14 extending into the heat exchange chamber 4-1 is provided in the lower layer of the heating catalyst box 4, and the high-temperature gas pipe 14 is connected to the catalyst chamber 4-3. Two lower baffles 14 are fixed at a distance in the lower layer of the heating catalyst box 4 below the heat exchange chamber 4-1. One of the lower baffles 14 is located below the right side of the one-way airflow heat exchanger 8 on the left, and the other lower baffle 14 is located below the right side of the one-way airflow heat exchanger 8 on the right. A preheating return air pipe 15 is connected between the bottom plate of the heating catalyst box 4 located between the two lower baffles 14 and the top plate of the preheating box 3.

[0030] The treatment process is briefly described as follows: the organic volatile waste gas located in the waste gas storage chamber 1 is powered by the blower 6 and enters the triangular prism cavity 3-1 on the upper left side of the preheating box 3 through the air intake pipe 6, and then flows from the upper left to the lower right through the one-way air inlet duct 8-2 of the first one-way air flow heat exchanger 8 in the preheating box 3 to enter the second group of triangular prism cavities 3-1 below, and then flows from the lower left to the upper right through the second one-way air flow heat exchanger 8, and finally flows from the upper left to the lower right through the third one-way air flow heat exchanger 8. Due to the special structure of the one-way air inlet duct 8-2, the gas can only enter but not exit, and the adjacent side surfaces of the one-way air flow heat exchanger 8 are not connected to each other. Finally, the waste gas flows into the triangular prism cavity 3-1 on the lower right side of the preheating box 3.

[0031] Through the action of the blower 6, the exhaust gas pipeline in the triangular prism cavity 3-1 at the lower right side of the preheating box 3 is transmitted into the rightmost cavity of the upper heat exchange cavity 4-1 inside the heating catalytic box 4. The exhaust gas flows through the two unidirectional airflow heat exchangers 8 in the heat exchange cavity 4-1 in turn. The movable hinge 10 drives the baffle bracket 9 between the heat exchange cavity 4-1 and the heating cavity 4-2 to open, and the exhaust gas passes into the heating cavity 4-2. Then the baffle bracket 9 is closed, and the heating wire 12 heats the gas entering the heating cavity 4-2. When the temperature displayed by the temperature sensor set in the heating cavity 4-2 reaches about 400℃, the baffle bracket 9 between the heating cavity 4-2 and the catalytic cavity 4-3 is opened by the movable hinge 10, and the heated exhaust gas enters the catalytic cavity 4-3. The precious metal honeycomb ceramic catalyst 13 catalyzes the exhaust gas. The organic molecules in the exhaust gas undergo a deep oxidation reaction under the action of the catalyst surface, and are converted into harmless carbon dioxide and water, which are temporarily stored in the gas retention chamber on the left side of the catalytic cavity 4-3.

[0032] Since the gas after the reaction carries relatively high temperature waste heat, the high temperature gas in the gas retention room on the left side of the catalytic chamber 4-3 is passed through the high temperature gas pipe 14 to the bottom of the one-way air flow heat exchanger 8 on the left side of the heat exchange chamber. Due to the action of the lower baffle 14, the high temperature gas flows upward, rightward and downward from the bottom of the one-way air flow heat exchanger 8 on the left side through the one-way exhaust duct 8-3 into the heat exchange box 8-1, and conducts heat convection with the metal sheet inside the heat box 8-1. Due to the formation of the one-way exhaust duct 8-3, the high temperature gas flows upward, rightward and downward from the bottom of the one-way air flow heat exchanger 8 on the left side, and enters the heat exchange box 8-1. The structural characteristics make the gas only go out but not in. The gas is discharged from the one-way airflow heat exchanger 8 on the left, and then enters the heat exchange box 8-1 of the one-way airflow heat exchanger 8 on the right from the one-way exhaust duct 8-3. Part of the heat of the gas is stored in the heat exchange box 8-1 of the one-way airflow heat exchanger 8 on the right. The upper baffle 11 and the lower baffle 14 are used to block the airflow. At this point, the gas completes the first-level waste heat recovery, and the heat recovered by the one-way airflow heat exchanger 8 is used for the second-level heating of the exhaust gas in the next process.

[0033] Since the gas after the first-stage waste heat recovery has completed still has some heat that has not been completely recovered, the gas between the two lower baffles 14 is passed through the preheating return pipe 15 into the triangular prism cavity 3-1 in the upper right area of ​​the preheating box 3. The special structure of the one-way exhaust duct 8-3 is used to

[0034] The gas passes through the three unidirectional airflow heat exchangers 8 in the preheating box 3 in the upper right, lower left, and upper right directions, and reaches the triangular prism cavity 3-1 on the lower left side of the preheating box 3. During this process, the metal sheets inside the heat exchange box body 8-1 of the three unidirectional airflow heat exchangers 8 continuously absorb and store the heat of the gas, which is used for preliminary heating of the exhaust gas in the next process, reducing the power consumption of the heating wire 12 in the next process. At this point, the secondary waste heat recovery is completed; at this time, the gas close to room temperature is acted upon by the blower 6 and enters the exhaust chimney 4 through the exhaust pipe 7 and is discharged to the outside.

[0035] With the above-described preferred embodiments of the present invention as a guide, and with reference to the above description, relevant personnel are fully capable of making various changes and modifications without departing from the technical scope of this invention. The technical scope of this invention is not limited to the contents of the specification and must be determined according to the scope of the claims.

Claims

1. A VOCs waste gas treatment device based on secondary waste heat recovery, characterized by: include The preheating box has an air inlet end that is fed with the waste gas to be treated. The left side of the preheating box is connected to an air inlet pipe and an exhaust pipe. The preheating box is provided with three unidirectional airflow heat exchangers of the same structure. The three unidirectional airflow heat exchangers are arranged at a 45-degree angle and connected end to end to divide the preheating box into eight closed triangular prism cavities. The eight triangular prism cavities are spaced apart along the length of the preheating box in groups of two, with the two triangular prism cavities in each group distributed vertically. The air inlet duct is connected to the triangular prism cavity in the upper left corner of the preheating box, and the exhaust duct is connected to the triangular prism cavity in the lower left corner of the preheating box. The heating catalytic box has a double-layer structure inside. The upper layer has a heat exchange chamber, a heating chamber and a catalytic chamber from right to left. The right air inlet end of the heating catalytic box is connected to the right air outlet end of the preheating box through a pipeline to pass the preheated gas into the heat exchange chamber. The heat exchange chamber and the heating chamber, as well as the heating chamber and the catalytic chamber, are connected or closed respectively by movable baffle brackets. Two one-way airflow heat exchangers are arranged side by side in the heat exchange cavity, wherein an upper baffle is fixedly connected between the right side of the one-way airflow heat exchanger and the upper inner wall of the heating catalyst box, an electric heating wire is installed in the heating cavity, and a precious metal honeycomb ceramic catalyst is arranged in the catalyst cavity; A high-temperature gas pipe connected to the catalytic chamber is provided in the lower layer of the heating catalytic box. Two lower baffles are fixed at a distance in the lower layer of the heating catalytic box below the heat exchange chamber. The two lower baffles are respectively located below the right side of the two unidirectional airflow heat exchangers. A preheating return air pipe is connected between the heating catalytic box and the preheating box between the two lower baffles.

2. The VOCs waste gas treatment device based on secondary waste heat recovery according to claim 1 is characterized in that: The air inlet pipe is connected to a waste gas storage chamber, and the exhaust pipe is connected to a discharge chimney.

3. The VOCs waste gas treatment device based on secondary waste heat recovery according to claim 1 is characterized in that: The one-way airflow heat exchanger includes a heat exchange box body, in which mutually perpendicular one-way air inlet ducts and one-way air exhaust ducts are provided. The gas introduced into the one-way air inlet duct of the previous one-way airflow heat exchanger enters the one-way air inlet duct of the next one-way airflow heat exchanger, and the gas discharged from the one-way exhaust duct of the previous one-way airflow heat exchanger enters the one-way exhaust duct of the next one-way airflow heat exchanger.

4. The VOCs waste gas treatment device based on secondary waste heat recovery according to claim 1 is characterized in that: The baffle bracket is pushed and moved by the movable hinge to realize the connection or closing between the heat exchange chamber and the heating chamber, and between the heating chamber and the catalytic chamber.

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