Low-temperature flue gas purification system
By designing a low-temperature flue gas purification system, using heat exchangers and flue gas heating devices to heat up the flue gas, the toxicity problem of liquid water and sulfur oxides in the low-temperature flue gas to CO catalysts is solved, and the flue gas temperature is adjusted through the bypass flue and circulating flue to ensure the safe operation of the system and the CO emission reduction efficiency.
Patent Information
- Application Number
- CN202411952476.5
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-12-27
- Publication Date
- 2025-03-14
AI Technical Summary
Under the condition of starting the main machine, the low-temperature flue gas contains a large amount of liquid water and high concentration of sulfur oxides, which leads to toxicity to the CO catalyst, and fluctuations in the smoke temperature may cause the rotary flue gas heat exchanger to become stuck.
A low-temperature flue gas purification system is designed, including a heat exchanger, a flue gas heating device and a reactor. Through the combination of heat exchanger and a flue gas heating device, the flue gas is heated up to avoid the influence of liquid water and sulfur oxides on the catalyst, and the flue gas temperature is adjusted through the bypass flue and circulating flue to ensure the safe operation of the system.
It effectively avoids the toxicity of liquid water and high concentration of sulfur oxides in low-temperature flue gas to CO catalysts, stabilizes the flue gas temperature, prevents heat exchanger from getting stuck, and ensures CO emission reduction efficiency and safe operation of the system.
Smart Images
Figure CN119617439A_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to the field of environmental protection, and in particular to a low-temperature flue gas purification system. Background Art
[0002] At present, the domestic sintering and pelletizing, thermal power, coking, carbon, metal smelting, chemical industry, etc. have basically completed the ultra-low emission transformation of desulfurization and denitrification. CO is the pollutant with the largest emission volume at present. The treatment technologies for CO include oxygen-enriched combustion, steam injection, flue gas recirculation, combustion optimization, etc., but the removal efficiency of these methods is limited. The CO catalytic oxidation combustion method has attracted much attention as a high-efficiency technology, and its removal efficiency can reach more than 80%.
[0003] CO catalytic oxidation combustion technology refers to the process of passing flue gas with a certain temperature (>240°C) through a specific CO catalyst, where CO undergoes an exothermic reaction on the catalyst surface to generate CO2. Therefore, the flue gas temperature at the catalyst layer outlet is often higher, which can easily cause the rotary flue gas heat exchanger to become stuck.
[0004] Existing studies have shown that H2O in the gas will change the surface morphology of the CO catalyst, causing irreversible loss of some active sites; sulfur oxides are poisonous to CO catalysts because they can form sulfates on the surface of the catalyst carrier to weaken the active sites, affect Pt-CO bonding, and reduce Pt's adsorption of CO. In other words, the application conditions of CO catalysts are harsh, and if there is liquid water and sulfur oxides in the flue gas, they will have a poisonous effect on the catalyst.
[0005] At present, major domestic industries have basically completed the ultra-clean emission transformation of desulfurization and denitrification, including activated coke integrated desulfurization and denitrification devices, sodium bicarbonate dry desulfurization devices, etc. If CO emission reduction is to be achieved, an independent CO removal device must be added after the desulfurization and denitrification device to achieve efficient CO removal. However, under the main engine startup condition, the flue gas temperature is low and will carry a large amount of liquid water. At the same time, the desulfurization and denitrification device has not been fully and stably put into operation, and the sulfur oxide emission concentration in the flue gas is unstable. The flue gas entering the CO removal device contains a large amount of sulfur oxides. Therefore, under the main engine startup condition, how to reduce the impact of low-temperature flue gas on CO catalysts, how to control the rise in flue gas temperature, and how to reduce the impact of high-temperature flue gas after catalytic combustion on the safe operation of rotary flue gas heat exchange are urgent problems to be solved. Summary of the invention
[0006] The purpose of the present invention is to provide a low-temperature flue gas purification system, which can avoid the influence of liquid water and high-concentration sulfur oxides in the low-temperature flue gas on the catalyst and solve the problem of heat exchanger blockage caused by flue gas temperature fluctuation.
[0007] In order to solve the above technical problems, the present invention adopts the following technical solutions.
[0008] The present invention provides a low-temperature flue gas purification system, which includes a heat exchanger, a flue gas heating device and a reactor. The flue gas inlet on the original flue gas side of the heat exchanger is used to connect to the flue gas outlet of the desulfurization and denitrification device, the flue gas inlet of the desulfurization and denitrification device is connected to the flue gas outlet of the host, the flue gas outlet on the original flue gas side of the heat exchanger is connected to the flue gas inlet of the flue gas heating device, the flue gas outlet of the flue gas heating device is connected to the flue gas inlet of the reactor through the reactor inlet flue, a catalyst is arranged in the reactor, and the flue gas of the flue gas heating device is connected to the flue gas outlet of the reactor. The outlet is also connected to the smoke inlet on the clean smoke gas side of the heat exchanger through a bypass flue, and the smoke outlet of the reactor is connected to the smoke inlet on the clean smoke gas side of the heat exchanger. The smoke outlet on the clean smoke gas side of the heat exchanger is used to discharge the clean smoke gas to the outside. The smoke outlet on the clean smoke gas side of the heat exchanger is also connected to the smoke inlet on the original smoke gas side of the heat exchanger through a circulating flue. An adjustable reactor inlet flue windshield is provided on the reactor inlet flue, an adjustable bypass flue windshield is provided on the bypass flue, and an adjustable circulating flue windshield is provided on the circulating flue.
[0009] In some embodiments of the present application, the smoke inlet and the smoke outlet on the raw smoke side of the heat exchanger and the smoke inlet and the smoke outlet on the clean smoke side of the heat exchanger are all provided with temperature measuring instruments.
[0010] In some embodiments of the present application, a reactor inlet wind speed detector is provided on the reactor inlet flue, a bypass flue wind speed detector is provided on the bypass flue, and a circulating flue wind speed detector is provided on the circulating flue.
[0011] In some embodiments of the present application, the low-temperature flue gas purification system further includes a controller;
[0012] The controller signal is connected to each of the temperature measuring instruments, the reactor inlet wind speed detector, the bypass flue wind speed detector and the circulating flue wind speed detector, and the controller controls the reactor inlet wind shield, the bypass flue wind shield and the circulating flue wind shield.
[0013] In some embodiments of the present application, the low-temperature flue gas purification system further includes an induced draft fan;
[0014] The smoke outlet on the clean smoke side of the heat exchanger is connected to the smoke inlet of the induced draft fan;
[0015] The smoke outlet of the induced draft fan is used to discharge clean smoke to the outside, and the smoke outlet of the induced draft fan is also connected to the smoke inlet of the original smoke side of the heat exchanger through a circulating smoke duct.
[0016] In some embodiments of the present application, the low-temperature flue gas purification system further includes a chimney;
[0017] The smoke outlet of the induced draft fan is connected to the chimney to discharge clean smoke to the outside through the chimney.
[0018] In some embodiments of the present application, a plurality of shelves are provided in the reactor and are arranged at intervals along the flow direction of the flue gas, and the shelves are used to place the catalyst.
[0019] In some embodiments of the present application, the desulfurization and denitrification device is a wet desulfurization and denitrification device, a semi-dry desulfurization and denitrification device, or a dry desulfurization and denitrification device.
[0020] In some embodiments of the present application, the heat exchanger is a rotary flue gas heat exchanger.
[0021] In some embodiments of the present application, the catalyst is one or more of a carbon monoxide removal catalyst, a methane removal catalyst, and a non-methane total hydrocarbon removal catalyst.
[0022] It can be seen from the above technical solutions that the embodiments of the present invention have at least the following advantages and positive effects:
[0023] In the low-temperature flue gas purification system of the embodiment of the present invention, taking the purification of carbon monoxide in flue gas as an example, the catalyst in the reactor is a carbon monoxide removal catalyst.
[0024] Under the main engine startup condition, the desulfurization and denitrification equipment has not yet been officially put into operation, and the flue gas temperature has not reached the ignition temperature of the CO catalyst. In order to avoid the flue gas temperature being too low, the liquid water and sulfur oxides in the flue gas will poison the CO catalyst.
[0025] At this time, the bypass flue windshield and the circulating flue windshield are opened, and the flue gas heating device is turned on at the same time, and the flue gas circulates between the heat exchanger, the bypass flue and the circulating flue. The flue gas is heated by the heat exchanger and the flue gas heating device. This can avoid the influence of liquid water and high concentration of sulfur oxides in the low-temperature flue gas on the CO catalyst.
[0026] During the process of flue gas temperature rising, the reactor inlet flue windshield is gradually opened, and at the same time, the bypass flue windshield and the circulating flue windshield are gradually closed. When the flue gas temperature and sulfur oxide concentration are stable, the bypass flue windshield and the circulating flue windshield are completely closed. At this time, the CO in the flue gas gradually reacts to form CO2 under the action of the CO catalyst, achieving CO emission reduction.
[0027] Since the CO catalytic combustion reaction releases a large amount of heat and the CO concentration in the flue gas is in a fluctuating state, if the CO concentration in the flue gas is too high, it will inevitably cause the flue gas inlet temperature on the clean flue gas side of the heat exchanger to be higher than the design value. To avoid excessively high flue gas temperature causing the heat exchanger to become stuck. To avoid safety hazards, it is necessary to open the bypass flue duct damper at this time, so that part of the flue gas does not pass through the CO catalyst and directly enters the flue gas inlet on the clean flue gas side of the heat exchanger, thereby reducing the flue gas temperature at the flue gas inlet on the clean flue gas side of the heat exchanger and achieving flue gas temperature control. By setting up bypass flues and circulating flues, the impact of low flue gas temperature on the CO catalyst under host startup conditions and the temperature control problem during system operation can be effectively solved. BRIEF DESCRIPTION OF THE DRAWINGS
[0028] Various objects, features and advantages of the present invention will become more apparent by considering the following detailed description of preferred embodiments of the present invention in conjunction with the accompanying drawings. The accompanying drawings are merely exemplary illustrations of the present invention and are not necessarily drawn to scale. In the accompanying drawings, the same reference numerals always represent the same or similar parts.
[0029] in:
[0030] Figure 1 is a schematic structural diagram of a low-temperature flue gas purification system according to an exemplary embodiment.
[0031] The description of the reference numerals is as follows: 1. Main engine; 2. Desulfurization and denitrification device; 3. Low-temperature flue gas purification system; 4. induced draft fan; 31. Heat exchanger; 32. Flue gas heating device; 33. Reactor; 34. Reactor inlet flue; 35. Bypass flue; 36. Circulating flue; 37. Reactor inlet flue wind shield; 38. Bypass flue wind shield; 39. Circulating flue wind shield; 311. Flue gas inlet on the raw flue gas side of the heat exchanger; 312. Flue gas outlet on the raw flue gas side of the heat exchanger; 313. Flue gas inlet on the clean flue gas side of the heat exchanger; 314. Flue gas outlet on the clean flue gas side of the heat exchanger. DETAILED DESCRIPTION
[0032] Although the present invention can be easily embodied in different forms of embodiments, only some of the specific embodiments are shown in the drawings and will be described in detail in this specification. It should be understood that this description should be regarded as an exemplary illustration of the principles of the invention and is not intended to limit the invention to that described herein.
[0033] Thus, a feature indicated in this specification will be used to illustrate one of the features of an embodiment of the present invention, rather than implying that each embodiment of the present invention must have the described feature. In addition, it should be noted that this specification describes many features. Although some features can be combined together to illustrate possible system designs, these features can also be used in other combinations that are not explicitly described. Thus, unless otherwise stated, the described combinations are not intended to be limiting.
[0034] In the embodiments shown in the drawings, the indications of directions (such as up, down, left, right, front and back) used to explain the structure and movement of various elements of the present invention are not absolute but relative. These descriptions are appropriate when these elements are in the positions shown in the drawings. If the description of the positions of these elements changes, the indications of these directions also change accordingly.
[0035] See also Figure 1 , Figure 1 is a schematic structural diagram of a low-temperature flue gas purification system 3 according to an exemplary embodiment.
[0036] The low-temperature flue gas purification system 3 includes a heat exchanger 31, a flue gas heating device 32 and a reactor 33. The flue gas inlet 311 on the original flue gas side of the heat exchanger is used to connect to the flue gas outlet of the desulfurization and denitration device 2. The flue gas inlet of the desulfurization and denitration device 2 is connected to the flue gas outlet of the host 1. The flue gas outlet 312 on the original flue gas side of the heat exchanger is connected to the flue gas inlet of the flue gas heating device 32. The flue gas outlet of the flue gas heating device 32 is connected to the flue gas inlet of the reactor 33 through the reactor inlet flue 34. The reactor 33 is provided with a catalyst. The flue gas outlet of the flue gas heating device 32 is also connected to the flue gas outlet of the reactor 33 through the bypass flue 34. The smoke inlet 313 of the clean smoke side of the heat exchanger is connected to the smoke inlet 313 of the clean smoke side of the heat exchanger, the smoke outlet of the reactor 33 is connected to the smoke inlet 313 of the clean smoke side of the heat exchanger, the smoke outlet 314 of the clean smoke side of the heat exchanger is used to discharge the clean smoke to the outside, and the smoke outlet 314 of the clean smoke side of the heat exchanger is also connected to the smoke inlet 311 of the raw smoke side of the heat exchanger through the circulating flue 36, the reactor inlet flue 34 is provided with an adjustable reactor inlet flue windshield 37, the bypass flue 35 is provided with an adjustable bypass flue windshield 38, and the circulating flue 36 is provided with an adjustable circulating flue windshield 39.
[0037] Through the above structural design, taking the purification of carbon monoxide in flue gas as an example, the catalyst in the reactor 33 is a carbon monoxide removal catalyst.
[0038] When the main engine 1 is started, the desulfurization and denitrification device 2 has not yet been officially put into operation, and the flue gas temperature has not reached the ignition temperature of the CO catalyst. In order to avoid the flue gas temperature being too low, the liquid water and sulfur oxides in the flue gas will poison the CO catalyst.
[0039] At this time, the bypass flue windshield 38 and the circulating flue windshield 39 are opened, and the flue gas heating device 32 is turned on at the same time, and the flue gas circulates between the heat exchanger 31, the bypass flue 35 and the circulating flue 36. The flue gas is heated by the heat exchanger 31 and the flue gas heating device 32. The influence of liquid water and high-concentration sulfur oxides in the low-temperature flue gas on the CO catalyst can be avoided.
[0040] During the process of flue gas temperature rising, the reactor inlet flue windshield 37 is gradually opened, and at the same time, the bypass flue windshield 38 and the circulating flue windshield 39 are gradually closed. When the flue gas temperature and sulfur oxide concentration are stable, the bypass flue windshield 38 and the circulating flue windshield 39 are completely closed. At this time, CO in the flue gas gradually reacts to form CO2 under the action of the CO catalyst, achieving CO emission reduction.
[0041] Since the CO catalytic combustion reaction releases a large amount of heat and the CO concentration in the flue gas is in a fluctuating state, if the CO concentration in the flue gas is too high, it will inevitably cause the temperature of the flue gas inlet 313 on the clean flue gas side of the heat exchanger to be higher than the design value. To avoid the heat exchanger 31 from getting stuck due to excessively high flue gas temperature. To avoid safety hazards, it is necessary to open the bypass flue windshield 38 at this time, so that part of the flue gas directly enters the flue gas inlet 313 on the clean flue gas side of the heat exchanger without passing through the CO catalyst, thereby reducing the flue gas temperature at the flue gas inlet 313 on the clean flue gas side of the heat exchanger and achieving flue gas temperature control. By setting up a bypass flue 35 and a circulating flue 36, the impact of low flue gas temperature on the CO catalyst under the startup condition of the main engine 1 and the temperature control problem during system operation can be effectively solved.
[0042] The flue gas inlet 311 and flue gas outlet 312 on the raw flue gas side of the heat exchanger and the flue gas inlet 313 and flue gas outlet 314 on the clean flue gas side of the heat exchanger are all equipped with thermometers. The thermometer can accurately grasp the current flue gas temperature and provide a reference for adjusting the reactor 33 inlet windshield, bypass flue windshield 38 and circulating flue windshield 39. Specifically,
[0043] During the flue gas temperature rise process, when the temperature of the flue gas outlet 312 on the original flue gas side of the heat exchanger reaches above 150°C, the reactor inlet flue damper 37 is gradually opened, and at the same time, the bypass flue damper 38 and the circulation flue damper 39 are gradually closed.
[0044] The reactor inlet flue 34 is provided with a reactor 33 inlet wind speed detector, the bypass flue 35 is provided with a bypass flue 35 wind speed detector, and the circulating flue 36 is provided with a circulating flue 36 wind speed detector. The wind speed in the flue can be accurately understood by the wind speed detector, so that the reactor 33 inlet wind shield, the bypass flue wind shield 38 and the circulating flue wind shield 39 can be accurately adjusted. Wind speed detectors include but are not limited to thermal anemometers, impeller anemometers, pitot tube anemometers, etc.
[0045] The low-temperature flue gas purification system 3 also includes a controller, the controller signal is connected to each temperature meter, the reactor 33 inlet wind speed detector, the bypass flue 35 wind speed detector and the circulating flue 36 wind speed detector, and the controller controls the reactor 33 inlet wind shield, the bypass flue wind shield 38 and the circulating flue wind shield 39. Based on the control system composed of the controller, the program can be set to automatically adjust the reactor 33 inlet wind shield, the bypass flue wind shield 38 and the circulating flue wind shield 39 according to the flue gas temperature and wind speed, so as to realize equipment automation and reduce labor costs.
[0046] The low-temperature flue gas purification system 3 also includes an induced draft fan 4. The flue gas outlet 314 on the clean flue gas side of the heat exchanger is connected to the flue gas inlet of the induced draft fan 4. The flue gas outlet of the induced draft fan 4 is used to discharge the clean flue gas to the outside. The flue gas outlet of the induced draft fan 4 is also connected to the flue gas inlet 311 on the raw flue gas side of the heat exchanger through the circulating flue 36. The induced draft fan 4 generates negative pressure to provide power for the flow of the flue gas.
[0047] The low-temperature flue gas purification system 3 also includes a chimney, and the flue gas outlet of the induced draft fan 4 is connected to the chimney to discharge clean flue gas outward through the chimney. It should be noted that the chimney is connected to the external environment, and the circulating flue 36 is in a negative pressure state during the startup stage. Therefore, during the flue gas circulation stage, the flue gas passing through the induced draft fan 4 will mainly enter the circulating flue 36 to participate in the flue gas circulation, and the flue gas will be heated by flue gas heat exchange and supplementary heat.
[0048] The reactor 33 is provided with a plurality of shelves spaced apart along the flow direction of the flue gas. The shelves are used to place catalysts, and the number of catalysts on the shelves can be adjusted according to the amount of flue gas purification.
[0049] It should be noted that the above embodiment is described by taking the removal of carbon monoxide in flue gas as an example, so the catalyst adopts a carbon monoxide removal catalyst. The low-temperature flue gas purification system 3 can also be used for the removal of other gases, for example, it is also suitable for the removal of methane, and the catalyst is replaced with a methane removal catalyst accordingly. For another example, it is also suitable for the removal of non-methane total hydrocarbons, and the catalyst is replaced with a non-methane total hydrocarbon removal catalyst accordingly. And the type of catalyst placed in the reactor 33 is not limited to one, and it can also be a combination of multiple catalysts.
[0050] The low-temperature flue gas purification system 3 can operate safely and independently, and can be coupled with various desulfurization and denitrification devices 2 in different industries, and can be one of a wet desulfurization and denitrification device 2, a semi-dry desulfurization and denitrification device 2, or a dry desulfurization and denitrification device 2. For example, but not limited to, an activated coke integrated desulfurization and denitrification device 2, a sodium bicarbonate dry desulfurization device, etc.
[0051] The host 1 may be an incinerator in the petrochemical industry, steel sintering, industrial kiln, etc. The heat exchanger 31 may be a rotary flue gas heat exchanger 31 .
[0052] By setting the reactor inlet flue windshield 37, the bypass flue windshield 38, and the circulating flue windshield 39, the full operating conditions can be met, the CO catalyst can be prevented from being poisoned by the start-up and shutdown and the flue gas is at a low temperature, and the catalytic efficiency of the CO catalyst can be ensured. It is also possible to close the reactor inlet flue windshield 37 and open the bypass flue windshield 38 to achieve online replacement and maintenance of the CO catalyst without affecting the operation of the original desulfurization and denitrification device 2. By adjusting the bypass flue windshield 38, the flue gas is diverted, and the purpose of flue gas temperature control is achieved while ensuring the removal efficiency.
[0053] Although the present invention has been described with reference to several typical embodiments, it should be understood that the terms used are illustrative and exemplary, rather than restrictive. Since the present invention can be embodied in a variety of forms without departing from the spirit or essence of the invention, it should be understood that the above embodiments are not limited to any of the foregoing details, but should be interpreted broadly within the spirit and scope defined by the appended claims, so all changes and modifications falling within the scope of the claims or their equivalents should be covered by the appended claims.
Claims
1. A low-temperature flue gas purification system, characterized in that: The low-temperature flue gas purification system comprises a heat exchanger, a flue gas heating device and a reactor. The flue gas inlet on the original flue gas side of the heat exchanger is used to connect to the flue gas outlet of the desulfurization and denitration device. The flue gas inlet of the desulfurization and denitration device is connected to the flue gas outlet of the host. The flue gas outlet on the original flue gas side of the heat exchanger is connected to the flue gas inlet of the flue gas heating device. The flue gas outlet of the flue gas heating device is connected to the flue gas inlet of the reactor through the reactor inlet flue. A catalyst is arranged in the reactor. The flue gas outlet of the flue gas heating device is also connected to the flue gas outlet of the reactor through the bypass flue. The duct is connected to the smoke inlet of the clean smoke gas side of the heat exchanger, the smoke outlet of the reactor is connected to the smoke inlet of the clean smoke gas side of the heat exchanger, the smoke outlet on the clean smoke gas side of the heat exchanger is used to discharge the clean smoke gas to the outside, the smoke outlet on the clean smoke gas side of the heat exchanger is also connected to the smoke inlet of the original smoke gas side of the heat exchanger through a circulating flue, the reactor inlet flue is provided with an adjustable reactor inlet flue wind shield, the bypass flue is provided with an adjustable bypass flue wind shield, and the circulating flue is provided with an adjustable circulating flue wind shield.
2. The low-temperature flue gas purification system according to claim 1, characterized in that: The smoke inlet and the smoke outlet on the raw smoke side of the heat exchanger and the smoke inlet and the smoke outlet on the clean smoke side of the heat exchanger are all provided with temperature measuring instruments.
3. The low-temperature flue gas purification system according to claim 2, characterized in that: The reactor inlet flue is provided with a reactor inlet wind speed detector, the bypass flue is provided with a bypass flue wind speed detector, and the circulating flue is provided with a circulating flue wind speed detector.
4. The low-temperature flue gas purification system according to claim 3, characterized in that: The low-temperature flue gas purification system also includes a controller; The controller signal is connected to each of the temperature measuring instruments, the reactor inlet wind speed detector, the bypass flue wind speed detector and the circulating flue wind speed detector, and the controller controls the reactor inlet wind shield, the bypass flue wind shield and the circulating flue wind shield.
5. The low-temperature flue gas purification system according to claim 1, characterized in that: The low-temperature flue gas purification system also includes an induced draft fan; The smoke outlet on the clean smoke side of the heat exchanger is connected to the smoke inlet of the induced draft fan; The smoke outlet of the induced draft fan is used to discharge clean smoke to the outside, and the smoke outlet of the induced draft fan is also connected to the smoke inlet of the original smoke side of the heat exchanger through a circulating smoke duct.
6. The low-temperature flue gas purification system according to claim 5, characterized in that: The low-temperature flue gas purification system also includes a chimney; The smoke outlet of the induced draft fan is connected to the chimney to discharge clean smoke to the outside through the chimney.
7. The low-temperature flue gas purification system according to claim 1, characterized in that: The reactor is provided with a plurality of shelves spaced apart along the flow direction of the flue gas, and the shelves are used to place the catalyst.
8. The low-temperature flue gas purification system according to claim 1, characterized in that: The desulfurization and denitrification device is one of a wet desulfurization and denitrification device, a semi-dry desulfurization and denitrification device or a dry desulfurization and denitrification device.
9. The low-temperature flue gas purification system according to claim 1, characterized in that: The heat exchanger is a rotary flue gas heat exchanger.
10. The low-temperature flue gas purification system according to claim 1, characterized in that: The catalyst is one or more of a carbon monoxide removal catalyst, a methane removal catalyst, and a non-methane total hydrocarbon removal catalyst.