VOCs treatment and waste heat recovery methods and systems

Abstract

This invention relates to a method and system for VOCs treatment and waste heat recovery. A VOCs treatment and waste heat recovery system includes a regenerating drying cylinder, which is connected to a cyclone dust collector via a first pipeline. The cyclone dust collector is connected to a plate filter via a second pipeline, and the plate filter is connected via a third pipeline. A heat exchanger is connected to an incinerator group via a fourth pipeline. The outlet of the incinerator group is connected to a fifth pipeline. One outlet of the fifth pipeline is connected to the heat inlet of the regenerating drying cylinder via a sixth pipeline, and the other outlet of the fifth pipeline is connected to the tube-side fluid inlet of the heat exchanger via a seventh pipeline. The heat exchanger is connected to the primary drying cylinder via an eighth pipeline, and the flue gas outlet of the primary drying cylinder is connected to post-treatment equipment. By setting up a heat exchanger, an incinerator group, and corresponding piping components, energy utilization efficiency can be improved. Simultaneously, setting up two incinerators can effectively save the gas consumption of a single incinerator, effectively conserving resources and reducing production costs.

Description

Technical Field

[0001] This invention relates to the field of VOCs treatment technology, and in particular to a VOCs treatment and waste heat recovery system. Background Technology

[0002] Asphalt recycling technology refers to the technique of adding a rejuvenating agent to old asphalt using asphalt recycling equipment to restore or approach its original properties. The asphalt mixing plant is the core equipment in asphalt recycling equipment, used to heat and mix the mixture of old asphalt and rejuvenating agents. During operation, the asphalt mixing plant generates VOCs (volatile organic compounds) in the flue gas. Its main components are benzo[a]pyrene, asphalt fumes, particulate matter, and other VOCs. The VOCs in the flue gas have the following characteristics:

[0003] (1) The exhaust temperature is relatively high, around 100℃;

[0004] (2) The flue gas also contains particulate matter that is released due to temperature changes.

[0005] For VOCs flue gas generated during the operation of asphalt mixing plants, the existing technology usually uses incinerators for treatment. After high-temperature incineration, the VOCs flue gas decomposes into carbon dioxide and water vapor, which are then cooled and discharged into the atmosphere.

[0006] However, since incinerators need to heat VOC flue gas to above 750°C, and then cool the carbon dioxide and water vapor obtained from the decomposition of VOC flue gas to meet emission standards, the heat carried by carbon dioxide and water vapor is wasted, resulting in low energy utilization. At the same time, in order to ensure complete decomposition of VOC flue gas, incinerators need to generate heat much higher than 750°C, resulting in large gas consumption by incinerators, which leads to resource waste and increased production costs. Summary of the Invention

[0007] To address the shortcomings of existing production technologies, the applicant provides a method and system for VOCs treatment and waste heat recovery. By setting up a heat exchanger, an incinerator group, and corresponding piping components, the heat generated during the incineration of VOCs components can be used to heat the regeneration drying cylinder and the primary drying cylinder, as well as to serve as a heat source for the heat exchanger, thereby improving energy utilization efficiency. At the same time, setting up two incinerators can effectively save the gas consumption of a single incinerator, effectively saving resources and reducing production costs.

[0008] The technical solution adopted in this invention is as follows:

[0009] A VOCs treatment and waste heat recovery system includes a regenerating drying cylinder. The flue gas outlet of the regenerating drying cylinder is connected to the inlet of a cyclone dust collector via a first pipeline. The outlet of the cyclone dust collector is connected to the inlet of a plate filter via a second pipeline. The outlet of the plate filter is connected to the shell-side fluid inlet of a heat exchanger via a third pipeline. The shell-side fluid outlet of the heat exchanger is connected to the inlet of an incinerator via a fourth pipeline. The outlet of the incinerator is connected to a fifth pipeline. One outlet of the fifth pipeline is connected to the heat inlet of the regenerating drying cylinder via a sixth pipeline. The other outlet of the fifth pipeline is connected to the tube-side fluid inlet of the heat exchanger via a seventh pipeline.

[0010] A first electric valve is installed on the first pipeline, a first fan is installed on the second pipeline, a second electric valve is installed on the sixth pipeline, and a third electric valve is installed on the seventh pipeline;

[0011] The tube-side fluid outlet of the heat exchanger is connected to the heat inlet of the primary drying drum through an eighth pipe. A second fan is installed on the eighth pipe, and a fourth electric valve is installed on the eighth pipe between the second fan and the heat exchanger. The flue gas outlet of the primary drying drum is connected to a post-treatment device, which performs dust removal and cooling treatment on the flue gas generated by the primary drying drum at a temperature below 200°C.

[0012] The inlet of the cyclone dust collector is connected to the flue gas outlet of the mixing tank of the asphalt mixing plant through the ninth pipeline, and the fifth electric valve is installed on the ninth pipeline.

[0013] As a further improvement to the above technical solution:

[0014] The incinerator group includes a first incinerator and a second incinerator connected in series. The first incinerator and the second incinerator are connected by a tenth pipeline, and the tenth pipeline is connected to the seventh pipeline through an eleventh pipeline.

[0015] The tenth pipeline is equipped with a sixth electric valve, and the eleventh pipeline is equipped with a seventh electric valve.

[0016] Both the first and second incinerators are equipped with combustible gas concentration detectors.

[0017] The heat exchanger is a plate heat exchanger.

[0018] The first fan is a variable frequency induced draft fan, and the second fan is a variable frequency return fan.

[0019] The cyclone dust collector adopts a tangential feeding method.

[0020] Temperature measuring instruments are installed on the regenerated drying cylinder, heat exchanger, incinerator group and original drying cylinder;

[0021] Negative pressure devices are installed on the regenerated drying cylinder, the incinerator group, and the primary drying cylinder.

[0022] A method utilizing the aforementioned VOCs treatment and waste heat recovery system, when the asphalt mixing plant and the recycling drying drum are operating simultaneously, includes the following steps:

[0023] The flue gas generated by the recycling drying drum enters the cyclone dust collector through the first pipeline; the flue gas generated by the mixing cylinder of the asphalt mixing plant enters the cyclone dust collector through the ninth pipeline.

[0024] The flue gas entering the cyclone dust collector is initially filtered under the action of centrifugal force and gravity;

[0025] The pre-filtered flue gas then passes through a plate filter to obtain secondary filtered flue gas;

[0026] The first fan sends the secondary filtered flue gas through the third pipeline into the shell-side fluid inlet of the heat exchanger. The heat exchanger heats the secondary filtered flue gas to 500°C, and then it enters the incinerator group through the fourth pipeline from the shell-side fluid outlet of the heat exchanger. The incinerator group heats the 500°C secondary filtered flue gas to 850°C, causing the VOCs components in the secondary filtered flue gas to decompose into carbon dioxide and water vapor, thereby obtaining mixed flue gas. The residence time of the 500°C secondary filtered flue gas in the incinerator group must be greater than or equal to two seconds.

[0027] A portion of the mixed flue gas sequentially passes through the fifth pipe, the sixth pipe, and the heat inlet of the recycling drying cylinder to enter the interior of the recycling drying cylinder, thereby heating the asphalt milling material inside the recycling drying cylinder; the residence time of the asphalt milling material in the recycling drying cylinder is greater than or equal to 8 minutes, thereby heating the asphalt milling material to 130℃-150℃; the temperature of the mixed flue gas at the heat inlet of the recycling drying cylinder is 750℃-850℃;

[0028] After the asphalt milling material is heated in the recycling drying cylinder, the mixed flue gas is cooled to 100℃-120℃, and then enters the cyclone dust collector through the flue gas outlet of the recycling drying cylinder and the first pipeline to form a cycle.

[0029] Another portion of the mixed flue gas enters the heat exchanger through the fifth pipeline, the seventh pipeline, and the tube-side fluid inlet of the heat exchanger, thereby heating the secondary filtered flue gas inside the heat exchanger to 500°C; the temperature of the mixed flue gas at the tube-side fluid inlet of the heat exchanger is 750°C-850°C.

[0030] The second fan sends the mixed flue gas in the heat exchanger into the primary drying cylinder through the eighth pipeline, which serves as the combustion gas for the primary drying cylinder burner to heat the primary material in the primary drying cylinder; the temperature of the mixed flue gas at the heat inlet of the primary drying cylinder is 300°C; the temperature of the exhaust gas generated after the primary drying cylinder heats the primary material is less than 200°C, and the exhaust gas is discharged into the atmosphere after being treated by post-treatment equipment for dust removal and cooling;

[0031] When only the asphalt mixing plant is operating, the following steps are included:

[0032] The first blower sequentially sends the flue gas generated by the mixing cylinder of the asphalt mixing plant through the cyclone dust collector, plate filter, and shell fluid inlet of the heat exchanger into the heat exchanger.

[0033] The heat exchanger heats the flue gas in the shell side to 500°C, and then enters the incinerator group through the fourth pipeline. The incinerator group heats the flue gas from 500°C to 850°C, causing the VOCs components in the secondary filtered flue gas to decompose into carbon dioxide and water vapor, thereby obtaining mixed flue gas.

[0034] The mixed flue gas sequentially enters the interior of the heat exchanger through the fifth pipeline, the seventh pipeline, and the tube-side fluid inlet of the heat exchanger, thereby heating the flue gas in the shell side of the heat exchanger to 500°C.

[0035] The second fan sends the mixed flue gas in the heat exchanger into the primary drying cylinder through the eighth pipeline, which serves as the combustion gas for the primary drying cylinder burner to heat the primary material in the primary drying cylinder. The exhaust gas generated after the primary drying cylinder heats the primary material is discharged into the atmosphere after being treated by the post-treatment equipment for dust removal and cooling.

[0036] As a further improvement to the above technical solution:

[0037] The mixed flue gas includes fine dust particles, carbon dioxide, and water vapor.

[0038] The beneficial effects of this invention are as follows:

[0039] This invention has a compact and reasonable structure and is easy to operate. By setting up a VOCs treatment and waste heat recovery system, the heat generated during the incineration of VOCs components can be used to heat the regeneration drying cylinder and the primary drying cylinder, as well as to serve as a heat source for the heat exchanger, thereby improving energy utilization. At the same time, setting up two incinerators can effectively save the gas consumption of a single incinerator, effectively save resources, and reduce production costs.

[0040] This invention provides a method for VOCs treatment and waste heat recovery. Based on the operating status of the VOCs treatment and waste heat recovery system, the flue gas is collected and then sequentially passed through a primary cyclone dust collector, a plate filter, a heat exchanger, and a secondary high-temperature incineration process to obtain mixed flue gas at 750℃-850℃. The high-temperature mixed flue gas is then sent to a regeneration drying drum and a heat exchanger for reuse. The mixed flue gas after passing through the heat exchanger can also be used for auxiliary heating of the regeneration drying drum. It has a high heat utilization rate and can effectively save production costs.

[0041] By setting up two incinerators, namely the first incinerator 7 and the second incinerator 8, the present invention can effectively prevent the problem of incomplete decomposition of VOCs components in flue gas. At the same time, the gas consumption of a single incinerator is small and the energy utilization rate is high, which can effectively save the gas consumption of the incinerator, thereby saving resources and reducing production costs. Attached Figure Description

[0042] Figure 1 This is a schematic diagram of the VOCs treatment and waste heat recovery system in this invention.

[0043] The components include: 1. Regenerated drying drum; 2. First electric valve; 3. Cyclone dust collector; 4. Plate filter; 5. First fan; 6. Heat exchanger; 7. First incinerator; 8. Second incinerator; 9. Second electric valve; 10. Third electric valve; 11. Storage silo; 12. Fourth electric valve; 13. Fifth electric valve; 14. Sixth electric valve; 15. Seventh electric valve; 16. Second fan; 17. Primary drying drum; 18. Post-processing equipment; 19. Combustible gas concentration detector. Detailed Implementation

[0044] The specific embodiments of the present invention will now be described with reference to the accompanying drawings.

[0045] Example 1:

[0046] like Figure 1As shown, the VOCs treatment and waste heat recovery system of this embodiment includes a regeneration drying cylinder 1. The flue gas outlet of the regeneration drying cylinder 1 is connected to the inlet of a cyclone dust collector 3 via a first pipeline. The outlet of the cyclone dust collector 3 is connected to the inlet of a plate filter 4 via a second pipeline. The outlet of the plate filter 4 is connected to the shell-side fluid inlet of a heat exchanger 6 via a third pipeline. The shell-side fluid outlet of the heat exchanger 6 is connected to the inlet of an incinerator group via a fourth pipeline. The outlet of the incinerator group is connected to a fifth pipeline. One outlet of the fifth pipeline is connected to the heat inlet of the regeneration drying cylinder 1 via a sixth pipeline, and the other outlet of the fifth pipeline is connected to the tube-side fluid inlet of the heat exchanger 6 via a seventh pipeline. The first pipeline is equipped with... There is a first electric valve 2, a first fan 5 installed on the second pipeline, a second electric valve 9 installed on the sixth pipeline, and a third electric valve 10 installed on the seventh pipeline; the fluid outlet of the heat exchanger 6 is connected to the heat inlet of the primary drying cylinder 17 through an eighth pipeline, a second fan 16 is installed on the eighth pipeline, a fourth electric valve 12 is installed on the eighth pipeline between the second fan 16 and the heat exchanger 6, the flue gas outlet of the primary drying cylinder 17 is connected to the post-treatment equipment 18, the post-treatment equipment 18 performs dust removal and cooling treatment on the flue gas generated by the primary drying cylinder 17 at a temperature below 200°C; the inlet of the cyclone dust collector 3 is connected to the flue gas outlet of the mixing cylinder of the asphalt mixing plant through a ninth pipeline, and a fifth electric valve 13 is installed on the ninth pipeline.

[0047] The incinerator unit includes a first incinerator 7 and a second incinerator 8 connected in series. The first incinerator 7 and the second incinerator 8 are connected by a tenth pipeline, which in turn is connected to a seventh pipeline via an eleventh pipeline. A sixth electric valve 14 is installed on the tenth pipeline, and a seventh electric valve 15 is installed on the eleventh pipeline. Both the first incinerator 7 and the second incinerator 8 are equipped with combustible gas concentration detectors 19. The first incinerator 7 heats the flue gas from 500℃ to above 750℃, thereby initially decomposing the VOCs components in the flue gas. Its calorific value is 3 million kcal / hour, and its gas consumption is 40-400 cubic meters / hour. The second incinerator 8 further heats the 750℃ flue gas to 850℃, thereby further ensuring the complete decomposition of the VOCs components in the flue gas. Its calorific value is 6.5 million kcal / hour, and its gas consumption is 85-850 cubic meters / hour.

[0048] By setting up two incinerators for segmented combustion, the heat output and gas consumption of a single incinerator can be effectively saved, and the heat utilization rate of a single incinerator can be improved.

[0049] The heat exchanger 6 is a plate heat exchanger. The first fan 5 is a variable frequency induced draft fan, and the second fan 16 is a variable frequency return fan. The cyclone dust collector 3 adopts a tangential feeding method. Since the flue gas contains relatively light dust particles, the oblique feeding method allows the cyclone dust collector 3 to complete the dust removal of the flue gas at a lower speed, thereby preventing the cyclone dust collector 3 from breaking up the dust particles in the flue gas at high speed and ensuring the dust removal effect. In this invention, by setting the feed port of the cyclone dust collector 3 along its radial direction, the feed direction of the cyclone dust collector 3 is parallel to its radial direction.

[0050] Temperature gauges are installed on the regenerated drying cylinder 1, heat exchanger 6, incinerator group, and primary drying cylinder 17; negative pressure gauges are also installed on the regenerated drying cylinder 1, incinerator group, and primary drying cylinder 17. The temperature gauges are used to measure the temperature of the gas inside the corresponding device. The corresponding electric valve can only be opened when the temperature measured by the temperature gauge meets the requirements; the negative pressure gauges are used to measure the pressure inside the corresponding device.

[0051] This embodiment provides a VOCs treatment and waste heat recovery system, wherein the inlet of the cyclone dust collector 3 is connected to the first pipeline and the ninth pipeline respectively through a three-way connector. The ninth pipeline is connected to the flue gas outlet of the mixing cylinder of the asphalt mixing plant, thereby introducing the flue gas generated by the mixing cylinder of the asphalt mixing plant into the cyclone dust collector 3.

[0052] The first pipeline connects to the flue gas outlet of the recycling drying cylinder 1, thereby introducing the flue gas generated by the recycling drying cylinder 1 into the cyclone dust collector 3. The recycling drying cylinder 1 is used to heat, stir, and mix the cold asphalt milling material.

[0053] Recycled drying cylinder 1 is used to heat asphalt milling material. Figure 1 In the middle, the arrow on one side of the recycling drying cylinder 1 indicates the opposite direction of the asphalt milling material feed. The bottom of the recycling drying cylinder 1 is connected to the storage bin 11, which is used to store the asphalt milling material processed by the recycling drying cylinder 1.

[0054] The flue gas produced by the recycling drying drum 1 has the same composition as the flue gas produced by the mixing drum of the asphalt mixing plant, both containing VOCs components, and their flue gas temperatures are both 100℃-120℃.

[0055] The plate filter 4 is used to further remove dust from the flue gas, filtering out even smaller dust particles in the flue gas;

[0056] The heat exchanger 6 is used to exchange heat with the flue gas. In this invention, the heat source used by the heat exchanger 6 is the mixed flue gas heated by the incinerator group.

[0057] Heat exchanger 6 heats flue gas that has passed through cyclone dust collector 3 and plate filter 4 at a temperature of less than 100°C to 500°C by using mixed flue gas heated by the incinerator group at a temperature of 750°C-850°C.

[0058] The virgin drying drum 17 is used to heat the virgin material. Figure 1 In the middle, the arrow on one side of the virgin drying cylinder 17 indicates the direction of virgin material feeding, and the arrow at the bottom of the virgin drying cylinder 17 indicates the direction of virgin material discharging from the virgin drying cylinder 17.

[0059] The exhaust gas generated during the operation of the primary drying drum 17 is treated by the post-treatment equipment 18 for dust removal and cooling, and is then discharged into the atmosphere after meeting the emission standards.

[0060] Electric valves are installed on the first, sixth, eighth, ninth, tenth, and eleventh pipelines to control the on / off state of the corresponding pipelines.

[0061] Example 2:

[0062] Using the VOCs treatment and waste heat recovery system provided in Embodiment 1, this embodiment provides a method for VOCs treatment and waste heat recovery, including the following steps:

[0063] When the asphalt mixing plant and the recycling drying drum 1 operate simultaneously, the following steps are included:

[0064] The flue gas generated by the regenerated drying cylinder 1 enters the cyclone dust collector 3 through the first pipeline; the flue gas generated by the mixing cylinder of the asphalt mixing plant enters the cyclone dust collector 3 through the ninth pipeline.

[0065] The flue gas entering the cyclone dust collector 3 is initially filtered under the action of centrifugal force and gravity;

[0066] The primary filtered flue gas then passes through plate filter 4 to obtain secondary filtered flue gas.

[0067] The first blower 5 sends the secondary filtered flue gas through the third pipeline into the shell-side fluid inlet of the heat exchanger 6. The heat exchanger 6 heats the secondary filtered flue gas inside to 500°C, and then sends it from the shell-side fluid outlet of the heat exchanger 6 through the fourth pipeline into the incinerator group. The incinerator group heats the 500°C secondary filtered flue gas to 850°C, causing the VOCs components in the secondary filtered flue gas to decompose into carbon dioxide and water vapor, thereby obtaining mixed flue gas. The residence time of the 500°C secondary filtered flue gas in the incinerator group must be greater than or equal to two seconds.

[0068] A portion of the mixed flue gas sequentially passes through the fifth pipe, the sixth pipe, and the heat inlet of the recycling drying cylinder 1 to enter the interior of the recycling drying cylinder 1, thereby heating the asphalt milling material inside the recycling drying cylinder 1; the residence time of the asphalt milling material in the recycling drying cylinder 1 is greater than or equal to 8 minutes, thereby heating the asphalt milling material to 130℃-150℃; the temperature of the mixed flue gas at the heat inlet of the recycling drying cylinder 1 is 750℃-850℃;

[0069] After the asphalt milling material is heated by the recycling drying cylinder 1, the mixed flue gas is cooled to 100℃-120℃, and then enters the cyclone dust collector 3 through the flue gas outlet of the recycling drying cylinder 1 and the first pipeline to form a cycle.

[0070] Another part of the mixed flue gas enters the interior of the heat exchanger 6 through the fifth pipeline, the seventh pipeline, and the tube-side fluid inlet of the heat exchanger 6 in sequence, thereby heating the secondary filtered flue gas inside the heat exchanger 6 to 500°C; the temperature of the mixed flue gas at the tube-side fluid inlet of the heat exchanger 6 is 750°C-850°C.

[0071] The second fan 16 sends the mixed flue gas in the heat exchanger 6 into the primary drying cylinder 17 through the eighth pipeline, which serves as the combustion gas for the burner of the primary drying cylinder 17 to heat the primary raw material in the primary drying cylinder 17; the temperature of the mixed flue gas at the heat inlet of the primary drying cylinder 17 is 300℃; the temperature of the exhaust gas generated by the primary drying cylinder 17 in heating the primary raw material is less than 200℃, and the exhaust gas is discharged into the atmosphere after being dusted and cooled by the post-treatment equipment 18;

[0072] When only the asphalt mixing plant is operating, the following steps are included:

[0073] The flue gas generated by the mixing cylinder of the asphalt mixing plant is sequentially sent into the heat exchanger 6 through the shell-side fluid inlet of the cyclone dust collector 3, plate filter 4, and heat exchanger 6 via the first fan 5.

[0074] Heat exchanger 6 heats the flue gas in the shell side to 500°C, and then enters the incinerator group through the fourth pipeline. The incinerator group heats the flue gas from 500°C to 850°C, so that the VOCs components in the secondary filtered flue gas decompose into carbon dioxide and water vapor, thereby obtaining mixed flue gas.

[0075] The mixed flue gas sequentially passes through the fifth pipeline, the seventh pipeline, and the tube-side fluid inlet of the heat exchanger 6 to enter the interior of the heat exchanger 6, thereby heating the flue gas in the shell side of the heat exchanger 6 to 500°C.

[0076] The second fan 16 sends the mixed flue gas in the heat exchanger 6 into the primary drying cylinder 17 through the eighth pipeline. As the combustion gas for the burner of the primary drying cylinder 17, it heats the primary material in the primary drying cylinder 17. The exhaust gas generated by the primary drying cylinder 17 in heating the primary material is discharged into the atmosphere after being dusted and cooled by the post-treatment equipment 18.

[0077] The mixed flue gas includes fine dust particles, carbon dioxide, and water vapor.

[0078] This embodiment provides a method for VOCs treatment and waste heat recovery. By using the heat generated from treating VOCs components to heat the asphalt milling material in the regenerated drying cylinder 1, to heat the virgin material in the primary drying cylinder 17, and as the input heat source for the heat exchanger 6, the waste heat recovery rate can reach more than 90%, with high energy utilization and good reliability. This method can effectively save natural resources and improve resource utilization.

[0079] Example 3:

[0080] The difference between this embodiment and Embodiment 2 is that this embodiment takes the simultaneous operation of the asphalt mixing plant and the recycling drying drum 1 as an example, and provides a method for VOCs treatment and waste heat recovery, including the following steps:

[0081] S1. The flue gas generated by the regeneration drying cylinder 1 enters the cyclone dust collector 3 through the first pipeline;

[0082] The flue gas generated by the mixing tank of the asphalt mixing plant enters the cyclone dust collector 3 through the ninth pipeline.

[0083] S1.1. The flue gas temperature at the feed inlet of cyclone dust collector 3 is 100℃-120℃;

[0084] S1.2. The first pipeline and the ninth pipeline are independent of each other and do not affect each other. The pipeline opening and closing are controlled by electric valves.

[0085] The first and ninth pipelines can be connected independently, with only one of them being connected; or they can be connected simultaneously.

[0086] S1.3. At this time, both the first electric valve 2 and the fifth electric valve 13 are in the open state;

[0087] S2. The flue gas entering the cyclone dust collector 3 quickly fills the inlet section space. Then, under the action of centrifugal force, the dust particles in the flue gas are captured on the wall of the device. Then, with the help of gravity, the dust particles are kicked off the ash hopper, thus obtaining the pre-filtered flue gas.

[0088] S3. The primary filtered flue gas then passes through plate filter 4 to obtain secondary filtered flue gas;

[0089] S3.1. The plate filter 4 filters out smaller dust particles in the pre-filtered flue gas and causes them to fall into the ash hopper;

[0090] S4. The first blower 5 sends the secondary filtered flue gas through the third pipeline into the shell-side fluid inlet of the heat exchanger 6. The heat exchanger 6 heats the secondary filtered flue gas inside to 500°C, and then sends it from the shell-side fluid outlet of the heat exchanger 6 through the fourth pipeline into the incinerator group.

[0091] The incinerator unit heats the secondary filtered flue gas from 500°C to 850°C, causing the VOCs components in the secondary filtered flue gas to decompose into carbon dioxide and water vapor, thereby obtaining mixed flue gas.

[0092] The residence time of the secondary filtered flue gas at 500℃ in the incinerator group must be greater than or equal to two seconds;

[0093] S4.1. The temperature of the secondary filtered flue gas at the fluid inlet of the shell side of the heat exchanger is below 100 degrees Celsius;

[0094] S4.2. The first incinerator 7 heats the secondary filtered flue gas from 500°C to 750°C, causing the VOCs components in the secondary filtered flue gas to oxidize and decompose into harmless carbon dioxide and water vapor, thereby obtaining the initial mixed flue gas.

[0095] The residence time of the secondary filtered flue gas at 500℃ in the first incinerator 7 must be greater than or equal to one second;

[0096] S4.3. Subsequently, the initial mixed flue gas in the first incinerator 7 enters the second incinerator 8. The second incinerator 8 heats the initial mixed flue gas to 850°C to further oxidize and decompose the residual VOCs components, ensuring that the VOCs components in the flue gas are completely decomposed, thereby obtaining mixed flue gas.

[0097] The residence time of the initial mixed flue gas in the second incinerator 8 must be greater than or equal to one second;

[0098] S4.4. The components of the initial mixed flue gas include fine particulate matter, VOCs, carbon dioxide and water vapor;

[0099] The mixed flue gas includes fine particulate matter, carbon dioxide, and water vapor;

[0100] A portion of the mixed flue gas obtained in S5 and S4 passes through the fifth pipeline, the seventh pipeline, and the tube-side fluid inlet of the heat exchanger 6 in sequence, and enters the interior of the heat exchanger 6, thereby heating the secondary filtered flue gas inside the heat exchanger 6 to 500°C.

[0101] The temperature of the mixed flue gas at the tube-side fluid inlet of heat exchanger 6 is 750℃-850℃;

[0102] S5.1. Both the second electric valve 9 and the third electric valve 10 are in the open state;

[0103] After the recycled drying cylinder 1 in S6 and S5 heats the asphalt milling material, the mixed flue gas is cooled to 100℃-120℃, and then enters the cyclone dust collector 3 through the flue gas outlet of the recycled drying cylinder 1 and the first pipeline to form a cycle.

[0104] Another part of the mixed flue gas obtained in S7.S4. passes through the fifth pipeline, the sixth pipeline, and the heat inlet of the recycling drying cylinder 1 to enter the interior of the recycling drying cylinder 1, heating the asphalt milling material inside the recycling drying cylinder 1. The residence time of the asphalt milling material in the recycling drying cylinder 1 is greater than or equal to 8 minutes, thereby heating the asphalt milling material to 130℃-150℃.

[0105] The temperature of the mixed flue gas at the heat inlet of the regenerated drying cylinder 1 is 750℃-850℃;

[0106] S8. The second fan 16 sends the mixed flue gas in the heat exchanger 6 into the primary drying cylinder 17 through the eighth pipeline, which serves as the combustion gas for the burner of the primary drying cylinder 17 to heat the primary material in the primary drying cylinder 17.

[0107] The temperature of the mixed flue gas at the heat inlet of the original drying cylinder 17 is 300℃;

[0108] The temperature of the exhaust gas generated by the heating of the raw material in the raw drying drum 17 is less than 200°C. After the exhaust gas is treated by the post-treatment equipment 18 for dust removal and cooling, it is discharged into the atmosphere.

[0109] This embodiment takes the simultaneous operation of the asphalt mixing plant and the recycling drying drum 1 as an example to provide a method for VOCs treatment and waste heat recovery. This embodiment can decompose all the flue gas containing VOCs components generated when the asphalt mixing plant and the recycling drying drum 1 are working into carbon dioxide and water vapor, thereby effectively ensuring that the VOCs treatment results meet environmental protection requirements. At the same time, the heat generated during the VOCs treatment process can be used to heat the asphalt milling material in the recycling drying drum 1 and the virgin material in the virgin drying drum 17. The waste heat recovery rate can reach more than 90%, with high working efficiency, thereby effectively saving resources and reducing production costs.

[0110] This embodiment provides a method for VOCs treatment and waste heat recovery. By setting up two incinerators, namely the first incinerator 7 and the second incinerator 8, the problem of incomplete decomposition of VOCs components in flue gas can be effectively prevented. At the same time, the gas consumption of a single incinerator is small and the energy utilization rate is high, which can effectively save the gas consumption of the incinerator, thereby saving resources and reducing production costs.

[0111] Example 4:

[0112] The difference between this embodiment and Embodiment 2 is that this embodiment takes the operation of only the asphalt mixing plant as an example and provides a method for VOCs treatment and waste heat recovery, including the following steps:

[0113] S1. The flue gas generated by the mixing cylinder of the asphalt mixing plant is sequentially sent into the heat exchanger 6 through the shell-side fluid inlet of the cyclone dust collector 3, plate filter 4, and heat exchanger 6 by the first fan 5.

[0114] S1.1. The flue gas temperature at the feed inlet of cyclone dust collector 3 is 100℃-120℃;

[0115] S1.2. The flue gas temperature at the fluid inlet of the shell side of the heat exchanger is below 100 degrees Celsius;

[0116] S1.3. The first electric valve 2 is closed, and the fifth electric valve 13 is opened;

[0117] S2. Heat exchanger 6 heats the flue gas in the shell side to 500°C, and then enters the incinerator group through the fourth pipeline. The incinerator group heats the flue gas from 500°C to 850°C, so that the VOCs components in the secondary filtered flue gas decompose into carbon dioxide and water vapor, thereby obtaining mixed flue gas.

[0118] S2.1. The first incinerator 7 heats the flue gas from 500°C to 750°C, causing the VOCs components in the flue gas to oxidize and decompose into harmless carbon dioxide and water vapor, thereby obtaining the initial mixed flue gas.

[0119] The residence time of the 500°C flue gas in the first incinerator 7 must be greater than or equal to one second;

[0120] S2.2. Subsequently, the initial mixed flue gas in the first incinerator 7 enters the second incinerator 8. The second incinerator 8 heats the initial mixed flue gas to 850°C to further oxidize and decompose the residual VOCs components, ensuring that the VOCs components in the flue gas are completely decomposed, thereby obtaining mixed flue gas.

[0121] The residence time of the initial mixed flue gas in the second incinerator 8 must be greater than or equal to one second;

[0122] S2.3. The components of the initial mixed flue gas include fine particulate matter, VOCs, carbon dioxide and water vapor;

[0123] The mixed flue gas includes fine particulate matter, carbon dioxide, and water vapor;

[0124] S3. The mixed flue gas sequentially passes through the fifth pipeline, the seventh pipeline, and the tube-side fluid inlet of the heat exchanger 6 to enter the interior of the heat exchanger 6, thereby heating the flue gas in the shell side of the heat exchanger 6 to 500°C.

[0125] S3.1. The second electric valve 9 is closed, and the third electric valve 10 is opened;

[0126] S4. The second fan 16 sends the mixed flue gas in the heat exchanger 6 into the primary drying cylinder 17 through the eighth pipeline. As the combustion gas for the burner of the primary drying cylinder 17, it heats the primary material in the primary drying cylinder 17. The exhaust gas generated by the primary drying cylinder 17 in heating the primary material is discharged into the atmosphere after being dusted and cooled by the post-treatment equipment 18.

[0127] S4.1. The temperature of the mixed flue gas at the heat inlet of the original drying cylinder 17 is about 300℃;

[0128] S4.2. The post-processing equipment 18 includes multiple dust collectors arranged in sequence. The exhaust gas generated by the heating of the raw material by the raw drying drum 17 is treated by multiple dust collectors for dust removal and cooling, so that the temperature of the exhaust gas is reduced to 90℃-100℃ and the dust content meets the emission standards before being discharged into the atmosphere.

[0129] This embodiment takes the operation of only the asphalt mixing plant as an example to provide a method for VOCs treatment and waste heat recovery. In this embodiment, the heat generated during the VOCs treatment process is used as the combustion gas of the raw drying drum 17, so that the heat can be used to heat the raw material in the raw drying drum 17. The heat recovery rate can reach more than 70%, which is highly efficient.

[0130] The pipelines described in this invention include, but are not limited to, single pipes, as long as they can complete the connection between two structures.

[0131] The above description is an explanation of the present invention and not a limitation thereof. The scope of the present invention is defined by the claims. Within the scope of protection of the present invention, any form of modification may be made.

Claims

1. A VOCs treatment and waste heat recovery system, characterized in that: The device includes a regenerating drying cylinder (1), the flue gas outlet of which is connected to the inlet of a cyclone dust collector (3) via a first pipeline, the outlet of the cyclone dust collector (3) via a second pipeline, the outlet of a plate filter (4) via a second pipeline, the outlet of the plate filter (4) via a third pipeline, the shell-side fluid inlet of a heat exchanger (6) via a third pipeline, the shell-side fluid outlet of the heat exchanger (6) via a fourth pipeline, the outlet of the incinerator group via a fifth pipeline, one outlet of the fifth pipeline via a sixth pipeline, the heat inlet of the regenerating drying cylinder (1), and the other outlet of the fifth pipeline via a seventh pipeline, which is connected to the tube-side fluid inlet of the heat exchanger (6). A first electric valve (2) is installed on the first pipeline, a first fan (5) is installed on the second pipeline, a second electric valve (9) is installed on the sixth pipeline, and a third electric valve (10) is installed on the seventh pipeline. The tube fluid outlet of the heat exchanger (6) is connected to the heat inlet of the primary drying cylinder (17) through an eighth pipe. A second fan (16) is installed on the eighth pipe. A fourth electric valve (12) is installed on the eighth pipe between the second fan (16) and the heat exchanger (6). The flue gas outlet of the primary drying cylinder (17) is connected to a post-treatment device (18). The post-treatment device (18) performs dust removal and cooling treatment on the flue gas generated by the primary drying cylinder (17) at a temperature below 200°C. The inlet of the cyclone dust collector (3) is connected to the flue gas outlet of the mixing tank of the asphalt mixing plant through the ninth pipeline, and the fifth electric valve (13) is installed on the ninth pipeline. The incinerator group includes a first incinerator (7) and a second incinerator (8) connected in series. The first incinerator (7) and the second incinerator (8) are connected by a tenth pipeline, and the tenth pipeline is connected to the seventh pipeline through an eleventh pipeline.

2. The VOCs treatment and waste heat recovery system as described in claim 1, characterized in that: The tenth pipeline is equipped with a sixth electric valve (14), and the eleventh pipeline is equipped with a seventh electric valve (15).

3. The VOCs treatment and waste heat recovery system as described in claim 1, characterized in that: Combustible gas concentration detectors (19) are installed on both the first incinerator (7) and the second incinerator (8).

4. The VOCs treatment and waste heat recovery system as described in claim 1, characterized in that: The heat exchanger (6) is a plate heat exchanger.

5. The VOCs treatment and waste heat recovery system as described in claim 1, characterized in that: The first fan (5) is a variable frequency induced draft fan, and the second fan (16) is a variable frequency return fan.

6. The VOCs treatment and waste heat recovery system as described in claim 1, characterized in that: The cyclone dust collector (3) adopts a tangential feeding method.

7. The VOCs treatment and waste heat recovery system as described in claim 1, characterized in that: Temperature measuring instruments are installed on the regenerated drying cylinder (1), heat exchanger (6), incinerator group and original drying cylinder (17); Negative pressure devices are installed on the regenerated drying cylinder (1), the incinerator group, and the primary drying cylinder (17).

8. A method for using the VOCs treatment and waste heat recovery system as described in claim 1, characterized in that: When the asphalt mixing plant and the recycling drying drum (1) are working simultaneously, the following steps are included: The flue gas generated by the regenerated drying drum (1) enters the cyclone dust collector (3) through the first pipeline; the flue gas generated by the mixing cylinder of the asphalt mixing plant enters the cyclone dust collector (3) through the ninth pipeline; The flue gas entering the cyclone dust collector (3) is initially filtered under the action of centrifugal force and gravity; The primary filtered flue gas then passes through a plate filter (4) to obtain secondary filtered flue gas; The first fan (5) sends the secondary filtered flue gas through the third pipeline into the shell-side fluid inlet of the heat exchanger (6). The heat exchanger (6) heats the secondary filtered flue gas inside to 500°C, and then the gas enters the incinerator group through the fourth pipeline from the shell-side fluid outlet of the heat exchanger (6). The incinerator group heats the 500°C secondary filtered flue gas to 850°C, so that the VOCs components in the secondary filtered flue gas decompose into carbon dioxide and water vapor, thereby obtaining mixed flue gas. The residence time of the 500°C secondary filtered flue gas in the incinerator group must be greater than or equal to two seconds. A portion of the mixed flue gas sequentially passes through the fifth pipe, the sixth pipe, and the heat inlet of the recycling drying cylinder (1) to enter the interior of the recycling drying cylinder (1), thereby heating the asphalt milling material inside the recycling drying cylinder (1); the residence time of the asphalt milling material in the recycling drying cylinder (1) is greater than or equal to 8 minutes, thereby heating the asphalt milling material to 130℃-150℃; the temperature of the mixed flue gas at the heat inlet of the recycling drying cylinder (1) is 750℃-850℃; After the asphalt milling material is heated by the recycling drying cylinder (1), the mixed flue gas is cooled to 100℃-120℃, and then enters the cyclone dust collector (3) through the flue gas outlet of the recycling drying cylinder (1) and the first pipeline to form a cycle; Another part of the mixed flue gas passes through the fifth pipeline, the seventh pipeline, and the tube-side fluid inlet of the heat exchanger (6) in sequence and enters the interior of the heat exchanger (6), thereby heating the secondary filtered flue gas inside the heat exchanger (6) to 500°C; the temperature of the mixed flue gas at the tube-side fluid inlet of the heat exchanger (6) is 750°C-850°C. The second fan (16) sends the mixed flue gas in the heat exchanger (6) into the primary drying cylinder (17) through the eighth pipeline, which serves as the combustion gas for the burner of the primary drying cylinder (17) to heat the primary material in the primary drying cylinder (17); the temperature of the mixed flue gas at the heat inlet of the primary drying cylinder (17) is 300°C; the temperature of the exhaust gas generated after the primary drying cylinder (17) heats the primary material is less than 200°C, and the exhaust gas is discharged into the atmosphere after being treated and cooled by the post-treatment equipment (18); When only the asphalt mixing plant is operating, the following steps are included: The flue gas generated by the mixing cylinder of the asphalt mixing plant is sent into the heat exchanger (6) through the shell-side fluid inlet of the cyclone dust collector (3), plate filter (4), and heat exchanger (6) in sequence by the first fan (5). The heat exchanger (6) heats the flue gas in the shell side to 500°C, and then enters the incinerator group through the fourth pipeline. The incinerator group heats the flue gas at 500°C to 850°C, so that the VOCs components in the secondary filtered flue gas decompose into carbon dioxide and water vapor, thereby obtaining mixed flue gas. The mixed flue gas sequentially passes through the fifth pipeline, the seventh pipeline, and the tube-side fluid inlet of the heat exchanger (6) to enter the interior of the heat exchanger (6), thereby heating the flue gas in the shell side of the heat exchanger (6) to 500°C. The second fan (16) sends the mixed flue gas in the heat exchanger (6) into the raw drying cylinder (17) through the eighth pipeline. As the combustion gas of the burner of the raw drying cylinder (17), it heats the raw material in the raw drying cylinder (17). The exhaust gas generated after the raw material is heated by the raw drying cylinder (17) is discharged into the atmosphere after being dusted and cooled by the post-treatment equipment (18).

9. The VOCs treatment and waste heat recovery method as described in claim 8, characterized in that: The mixed flue gas includes fine dust particles, carbon dioxide, and water vapor.

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