RTO and SCR synergistic waste gas treatment system capable of efficiently utilizing waste heat
By installing heat exchangers in the RTO and SCR systems, the temperature gradient exchange and mixing of flue gas are achieved, which solves the problems of catalyst deactivation and heat energy waste caused by directly introducing high-temperature flue gas into the SCR system, and realizes efficient system operation and environmentally friendly emissions.
Patent Information
- Application Number
- CN202423235776.X
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2024-12-26
- Publication Date
- 2025-12-09
- Estimated Expiration
- 2034-12-26
AI Technical Summary
In existing RTO and SCR co-processing waste gas treatment systems, the direct introduction of high-temperature flue gas into the SCR system leads to catalyst deactivation, waste of thermal energy, and environmental pollution. Furthermore, the flue gas temperature at the SCR outlet is not suitable for direct emission.
By setting up first and second heat exchangers, the flue gas temperature gradient is exchanged, the inlet flue gas temperature of the SCR system is reduced, the waste gas to be treated is preheated by low-temperature flue gas, the energy consumption of RTO is reduced, and the temperature is regulated by flue gas mixing to prevent catalyst deactivation and white fog phenomenon.
This has enabled the safe operation of the SCR system, reduced RTO energy consumption, avoided catalyst damage and environmental pollution, and improved waste gas treatment efficiency.
Smart Images
Figure CN223649321U_ABST
Abstract
Description
Technical Field
[0001] This utility model relates to the field of waste gas treatment technology, and in particular to a waste gas treatment system that utilizes waste heat efficiently and combines RTO and SCR. Background Technology
[0002] RTO stands for Regenerative Thermal Oxidizer. It mainly consists of a combustion system, a heat storage system, a valve switching system, and a flue gas exhaust system. It is primarily used to treat VOCs. VOCs in the waste gas are oxidized and decomposed into CO2 and H2O. The temperature of the high-temperature flue gas after combustion can reach 760-850℃. However, for organic waste gas containing nitrogen, the high-temperature combustion of RTO will produce a large amount of nitrogen oxides, which need to be treated. This is the shortcoming of a single RTO.
[0003] SCR is a selective catalytic reduction technology that uses a catalyst to mix NOx in flue gas with ammonia from a reducing agent supply system at a certain temperature to undergo a selective catalytic reduction reaction, producing nitrogen and water, thereby reducing NOx emissions and mitigating flue gas pollution to the environment.
[0004] In the current technology for treating organic waste gas containing nitrogen, the combined RTO and SCR waste gas treatment system has become one of the best methods for treating such waste gas. However, because the high temperature of the RTO flue gas outlet is too high, directly introducing it into the SCR system can easily lead to catalyst deactivation. Moreover, the outlet flue gas temperature of the SCR system is also 230-300℃. Direct emission will not only waste heat energy, but also damage the chimney and pipes, and will also form white fog, causing secondary pollution to the environment. Summary of the Invention
[0005] The purpose of this invention is to overcome the shortcomings of the above-mentioned technologies and provide a waste heat-efficient RTO and SCR synergistic waste gas treatment system. By exchanging heat between the RTO outlet flue gas and the SCR outlet flue gas, the system achieves efficient utilization of thermal energy and improves the waste gas treatment effect of RTO and SCR.
[0006] To achieve the above-mentioned objectives, the technical solution adopted by this utility model is as follows:
[0007] A waste heat-efficient RTO and SCR synergistic waste gas treatment system is characterized by comprising an RTO device, an SCR system, a first heat exchanger, and a second heat exchanger; the high-temperature flue gas outlet of the RTO device is connected to the SCR system via a flue gas mixer; the flue gas outlet of the SCR system is connected to the high-temperature medium inlet of the first heat exchanger via a pipeline; the high-temperature medium outlet of the first heat exchanger is connected to the flue gas mixer via a pipeline; the low-temperature flue gas outlet of the RTO device is connected to the low-temperature medium inlet of the first heat exchanger via a pipeline; the low-temperature medium outlet of the first heat exchanger is connected to the high-temperature medium inlet of the second heat exchanger via a pipeline; the high-temperature medium outlet of the second heat exchanger is connected to a chimney via an induced draft fan; the waste gas to be treated by the RTO is connected to the low-temperature medium inlet of the second heat exchanger via a pipeline; and the low-temperature medium outlet of the second heat exchanger is connected to the flue gas inlet of the RTO device via a pipeline.
[0008] A further improvement of this invention is that the RTO device is a three-chamber RTO device, including a combustion chamber and three regenerative heat exchange chambers. The RTO device contains three regenerative heat exchange chambers, and the airflow direction is switched at regular intervals by an airflow switching valve to realize the cycle of heat absorption and heat release processes in the heat storage layer. When the high-temperature exhaust gas flows through the regenerative ceramic bed, it releases heat energy and is absorbed and stored by the heat storage body. This process will cause the exhaust gas temperature to drop significantly. The high-temperature flue gas is the exhaust gas that has just been discharged from the combustion chamber, while the low-temperature flue gas is the exhaust gas after heat exchange through the regenerative ceramic bed. At this time, the high-temperature flue gas and the low-temperature flue gas may coexist in the system and be discharged through different outlets.
[0009] A further improvement of this utility model is that the SCR system includes a static mixer, a filter and an SCR reactor connected in sequence. The flue gas outlet of the flue gas mixer is connected to the static mixer through a pipeline. The static mixer is equipped with an ammonia water atomizing nozzle. The flue gas outlet of the SCR reactor is connected to the high-temperature medium inlet of the first heat exchanger through a pipeline.
[0010] A further improvement of this utility model is that both the first heat exchanger and the second heat exchanger are plate heat exchangers.
[0011] A further improvement of this invention is that a regulating valve is installed on the connecting pipe between the high-temperature flue gas outlet of the RTO device and the flue gas mixer to regulate the amount of high-temperature flue gas entering the flue gas mixer.
[0012] The waste heat utilization process of the flue gas in the above system is as follows:
[0013] During system operation, the high-temperature flue gas outlet of the RTO unit discharges high-temperature flue gas (temperature 760–850°C). This high-temperature flue gas, together with the flue gas from the low-temperature medium outlet of the first heat exchanger (temperature 150–180°C), enters the flue gas mixer to form mixed flue gas (temperature 230–300°C), which then enters the SCR system for denitrification. The flue gas discharged from the SCR system (temperature 230–300°C) enters the high-temperature medium inlet of the first heat exchanger, where it mixes with the low-temperature flue gas from the RTO unit's low-temperature flue gas outlet (temperature approximately 120°C). The first heat exchanger heats the flue gas to 150-180°C by exchanging heat with the flue gas at a temperature of 135°C. The flue gas then enters the flue gas mixer. At this time, the flue gas (temperature 150-220°C) from the high-temperature medium outlet of the first heat exchanger enters the second heat exchanger and exchanges heat with the ambient temperature waste gas to be treated by the RTO. This raises the temperature of the waste gas entering the RTO to about 85°C, thus realizing the waste heat of the waste gas to be treated and reducing the energy consumption of the RTO. The flue gas temperature discharged from the second heat exchanger drops to below 150°C and is discharged through the chimney, which is harmless to the chimney pipes and the environment.
[0014] The beneficial effects of this utility model are as follows:
[0015] This invention utilizes dual heat exchangers to achieve gradient heat exchange, thereby reducing the temperature of the flue gas entering the SCR system to a suitable level for SCR denitrification. Simultaneously, it ensures the flue gas temperature entering the SCR system remains within a safe range, preventing excessively high flue gas temperatures from affecting the performance and lifespan of the SCR catalyst and guaranteeing efficient denitrification. Furthermore, by exchanging heat with the low-temperature flue gas from the RTO, the outlet flue gas of the SCR system is cooled, ensuring that the temperature of the flue gas entering the SCR system does not become too low, which could lead to SCR catalyst blockage. The heat from the remaining flue gas is used to preheat the waste gas to be treated, reducing the energy consumption of the RTO unit and also lowering the exhaust gas temperature to a safe range, preventing high-temperature damage to the chimney inner wall and eliminating white plume phenomenon. Attached Figure Description
[0016] Figure 1 This is a schematic diagram of the structure of this utility model.
[0017] In the diagram: 1. RTO unit; 2. SCR system; 3. First heat exchanger; 4. Second heat exchanger; 5. Flue gas mixer; 6. Exhaust fan; 7. Chimney; 8. Combustion chamber; 9. Regenerative heat exchange chamber; 10. Static mixer; 11. Filter; 12. SCR reactor; 13. Ammonia atomizing nozzle; 14. Regulating valve. Detailed Implementation
[0018] The technical solution of this utility model will be further described in detail below through specific embodiments and with reference to the accompanying drawings:
[0019] like Figure 1As shown, a waste heat-efficient RTO and SCR synergistic waste gas treatment system includes an RTO device 1, an SCR system 2, a first heat exchanger 3, and a second heat exchanger 4. The high-temperature flue gas outlet of the RTO device 1 is connected to the SCR system 2 through a flue gas mixer 5. The flue gas outlet of the SCR system 2 is connected to the high-temperature medium inlet of the first heat exchanger 3 through a pipeline. The high-temperature medium outlet of the first heat exchanger 3 is connected to the flue gas mixer 5 through a pipeline. The low-temperature flue gas outlet of the RTO device 1 is connected to the low-temperature medium inlet of the first heat exchanger 3 through a pipeline. The low-temperature medium outlet of the first heat exchanger 3 is connected to the high-temperature medium inlet of the second heat exchanger 4 through a pipeline. The high-temperature medium outlet of the second heat exchanger 4 is connected to a chimney 7 through an induced draft fan 6. The waste gas to be treated by the RTO is connected to the low-temperature medium inlet of the second heat exchanger 4 through a pipeline. The low-temperature medium outlet of the second heat exchanger 4 is connected to the flue gas inlet of the RTO device 1 through a pipeline.
[0020] In this embodiment, the RTO device 1 is a three-chamber RTO device 1, including a combustion chamber 8 and three regenerative heat exchange chambers 9. The RTO device 1 contains three regenerative heat exchange chambers 9. The airflow direction is switched at regular intervals by an airflow switching valve to realize the cycle of heat absorption and heat release processes in the heat storage layer. When the high-temperature exhaust gas flows through the heat storage ceramic bed, it releases heat energy and is absorbed and stored by the heat storage body. This process will cause the exhaust gas temperature to drop significantly. The high-temperature flue gas is the exhaust gas that has just been discharged from the combustion chamber, while the low-temperature flue gas is the exhaust gas after heat exchange through the heat storage ceramic bed. At this time, the high-temperature flue gas and the low-temperature flue gas may coexist in the system and be discharged through different outlets.
[0021] In this embodiment, the SCR system 2 includes a static mixer 10, a filter 11 and an SCR reactor 12 connected in sequence. The flue gas outlet of the flue gas mixer 5 is connected to the static mixer 10 through a pipe. The static mixer 10 is equipped with an ammonia water atomizing nozzle 13. The flue gas outlet of the SCR reactor 12 is connected to the high-temperature medium inlet of the first heat exchanger 3 through a pipe.
[0022] In this embodiment, both the first heat exchanger 3 and the second heat exchanger 4 are plate heat exchangers.
[0023] In this embodiment, a regulating valve 14 is installed on the connecting pipe between the high-temperature flue gas outlet of the RTO device 1 and the flue gas mixer 5 to regulate the amount of high-temperature flue gas entering the flue gas mixer 5.
[0024] The waste heat utilization process of the flue gas in the above system is as follows:
[0025] During system operation, high-temperature flue gas (760–850°C) is discharged from the high-temperature flue gas outlet of RTO unit 1. This high-temperature flue gas, along with the flue gas (150–180°C) from the low-temperature medium outlet of the first heat exchanger 3, enters the flue gas mixer 5 to form mixed flue gas (230–300°C), which then enters the SCR system 2 for denitrification. The flue gas (230–300°C) discharged from the flue gas outlet of the SCR system 2 enters the high-temperature medium inlet of the first heat exchanger 3, where it mixes with the low-temperature flue gas (approximately 120°C) from the low-temperature flue gas outlet of RTO unit 1. The flue gas undergoes heat exchange at a temperature of 150-180°C (approximately 135°C) and enters the flue gas mixer 5. At this time, the flue gas (temperature 150-220°C) from the high-temperature medium outlet of the first heat exchanger 3 enters the second heat exchanger 4 and exchanges heat with the ambient temperature waste gas to be treated by the RTO, raising the temperature of the waste gas entering the RTO device 1 to approximately 85°C. This allows the waste heat of the waste gas to be treated to be utilized, thereby reducing the energy consumption of the RTO. Meanwhile, the flue gas temperature discharged from the second heat exchanger 4 drops below 150°C and is discharged through the chimney 7, achieving harmlessness to the chimney 7 pipes and the environment.
[0026] Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of the present invention without departing from the principles and spirit of the present invention. Any simple modifications, equivalent changes and modifications made to the above embodiments based on the technical essence of the present invention shall still fall within the scope of the technical solution of the present invention.
Claims
1. A waste gas treatment system that efficiently utilizes waste heat through a combined RTO and SCR process, characterized in that, The system includes an RTO unit, an SCR system, a first heat exchanger, and a second heat exchanger. The high-temperature flue gas outlet of the RTO unit is connected to the SCR system via a flue gas mixer. The flue gas outlet of the SCR system is connected to the high-temperature medium inlet of the first heat exchanger via a pipeline. The high-temperature medium outlet of the first heat exchanger is connected to the flue gas mixer via a pipeline. The low-temperature flue gas outlet of the RTO unit is connected to the low-temperature medium inlet of the first heat exchanger via a pipeline. The low-temperature medium outlet of the first heat exchanger is connected to the high-temperature medium inlet of the second heat exchanger via a pipeline. The high-temperature medium outlet of the second heat exchanger is connected to a chimney via an induced draft fan. The waste gas to be treated by the RTO unit is connected to the low-temperature medium inlet of the second heat exchanger via a pipeline. The low-temperature medium outlet of the second heat exchanger is connected to the flue gas inlet of the RTO unit via a pipeline.
2. The waste heat-efficient RTO and SCR synergistic waste gas treatment system according to claim 1, characterized in that, The RTO device is a three-chamber RTO device, including a combustion chamber and three regenerative heat exchange chambers.
3. The waste heat-efficient RTO and SCR synergistic waste gas treatment system according to claim 1, characterized in that, The SCR system includes a static mixer, a filter, and an SCR reactor connected in sequence. The flue gas outlet of the flue gas mixer is connected to the static mixer through a pipeline. The static mixer is equipped with an ammonia water atomizing nozzle. The flue gas outlet of the SCR reactor is connected to the high-temperature medium inlet of the first heat exchanger through a pipeline.
4. The waste heat-efficient RTO and SCR synergistic waste gas treatment system according to claim 1, characterized in that, Both the first and second heat exchangers are plate heat exchangers.
5. The waste heat-efficient RTO and SCR synergistic waste gas treatment system according to claim 1, characterized in that, A regulating valve is installed on the connecting pipe between the high-temperature flue gas outlet of the RTO device and the flue gas mixer.