Medium and low temperature SCR flue gas denitration device for smelting kiln
Through the joint control of the thermal oil heat exchange system and the burner refueling system, the problems of high arsenic content and temperature fluctuations in the flue gas of the smelting kiln are solved, and the efficient and economical operation of medium and low temperature SCR flue gas is achieved, ensuring the stability and environmental protection of the denitrification system.
Patent Information
- Application Number
- CN202422568115.2
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2024-10-24
- Publication Date
- 2025-08-29
- Estimated Expiration
- 2034-10-24
AI Technical Summary
The arsenic content in the flue gas of the smelting kiln is high and the temperature fluctuates greatly. The existing SCR flue gas denitrogenation technology cannot be applied before desulfurization, resulting in high energy consumption, high cost and low denitrification efficiency, which makes it difficult to meet environmental protection requirements.
The combined control of the thermal oil heat exchange system, the GGH heat exchange system and the burner re-ignition system is adopted. The high-temperature flue gas heat is recovered through the thermal oil heat exchanger and released in the low-temperature flue gas section. Combined with the GGH heat exchanger and the burner re-ignition system, the flue gas temperature reaches the active temperature of the SCR denitrification catalyst above 230℃.
It effectively reduces energy losses, ensures the stable operation of denitrification systems, reduces operating costs, and ensures long-term emissions of pollutants.
Smart Images
Figure CN223283459U_ABST
Abstract
Description
Technical Field
[0001] The utility model relates to the field of smelting furnace flue gas treatment, in particular to a medium-low temperature SCR flue gas denitrification device for a smelting furnace. Background Art
[0002] At present, the flue gas of smelting furnaces has complex components and contains a large amount of heavy metals, especially arsenic. At the same time, the sulfur content in the flue gas before desulfurization is very high, sometimes as high as 50,000 mg / Nm 3 At the same time, the temperature of the flue gas from the smelting furnace fluctuates periodically according to the periodicity of the feed. Therefore, the denitrification of the flue gas from such smelting furnaces is a difficulty and pain point in this industry.
[0003] Conventional flue gas denitrification technologies primarily include selective catalytic reduction (SCRD) denitrification, selective non-catalytic reduction (SNCR) denitrification, and oxidation. Oxidation denitrification requires low one-time investment, simple equipment and process, and high NOx removal efficiency. However, it poses secondary pollution issues such as wastewater and ozone leakage, and is currently not being promoted. SNCR flue gas denitrification technology has high flue gas temperature requirements and low denitrification efficiency, making the system unable to meet environmental protection requirements continuously over the long term. Because arsenic in flue gas irreversibly affects the SCR denitrification catalyst, SCR denitrification of smelting furnace flue gas cannot be performed before desulfurization and arsenic removal. After desulfurization, the flue gas temperature is only around 60°C. Using conventional SCR denitrification processes requires heating the flue gas, which consumes a large amount of energy, resulting in high operating costs and unreasonable economics, making it unacceptable to enterprises. Therefore, this is a technical issue that urgently needs to be addressed. Utility Model Content
[0004] The purpose of the utility model is to overcome the above-mentioned shortcomings of the prior art and to provide a medium- and low-temperature SCR flue gas denitrification device for smelting furnaces, which can convert and reasonably utilize the inherent heat of the flue gas, perform temperature compensation on the low-temperature flue gas, reduce energy loss, and ensure the normal operation of the denitrification system.
[0005] The technical solution of the utility model is: a medium-low temperature SCR flue gas denitrification device for a smelting furnace, comprising a thermal oil heat exchange system, a GGH heat exchange system, a burner supplementary combustion system and a medium-low temperature SCR denitrification system, wherein the medium-low temperature SCR denitrification system is sequentially provided with a GGH heat exchange system, a thermal oil heat exchange system and a burner supplementary combustion system, the thermal oil heat exchange system comprises a thermal oil heat exchanger, and the heat transfer from high-temperature flue gas to low-temperature flue gas is completed by the thermal oil, the entire system is controlled by a control system, and a temperature testing device is provided at the front end of the burner supplementary combustion system; when the flue gas temperature at the outlet of the thermal oil heat exchanger is below 230°C, the burner supplementary combustion system is put into operation to perform temperature compensation on the flue gas, thereby ensuring that the flue gas temperature entering the SCR denitrification catalyst is higher than 230°C.
[0006] The advantage of this solution is that, through the combination of the thermal oil heat exchange system, the GGH heat exchange system and the burner supplementary combustion system, the three can coordinate and compensate for the flue gas temperature under the control of the control system. According to the specific situation of the flue gas temperature, the controller controls the burner supplementary combustion system to compensate for the flue gas temperature, thereby reducing energy loss. When the temperature detected by the temperature testing equipment is lower than the set value, the control system automatically controls the operation of the burner supplementary combustion system to compensate for the flue gas temperature, ensuring that the flue gas temperature entering the SCR denitrification catalyst is higher than 230°C; the GGH heat exchange system will use the high-temperature flue gas at the catalyst outlet to heat the low-temperature flue gas at the desulfurization tower outlet; then the flue gas after passing through the GGH heat exchanger is heated by the low-temperature heat exchanger. If the temperature after heat exchange is still lower than 230°C, the controller automatically controls the burner supplementary combustion system to compensate for the flue gas temperature according to the temperature detection signal.
[0007] Furthermore, the thermal oil heat exchange system is a closed system, further comprising a thermal oil pressurized circulation system and a thermal oil expansion tank. The thermal oil heat exchanger comprises a high-temperature flue gas heat exchanger and a low-temperature flue gas heat exchanger, which are connected via the thermal oil pressurized circulation system, and the thermal oil expansion tank is provided on the thermal oil pressurized circulation system. Preferably, the thermal oil pressurized circulation system comprises a thermal oil delivery pipe, a pump, and a valve. The high-temperature flue gas heat exchanger, the low-temperature flue gas heat exchanger, and the thermal oil expansion tank are connected via a delivery pipe equipped with a valve and a pump. The high-temperature flue gas heat exchanger is positioned at the high-temperature flue gas outlet of the kiln, and the low-temperature flue gas heat exchanger is positioned between the burner and the GGH heat exchange system to heat the low-temperature flue gas and increase its temperature.
[0008] Furthermore, the high-temperature flue gas heat exchanger is positioned after the flue gas cooling device at the smelting furnace outlet, while the low-temperature flue gas heat exchanger is positioned between the GGH heat exchanger and the afterburner to heat the low-temperature flue gas. Preferably, the high-temperature flue gas heat exchanger is used to recover heat from the high-temperature flue gas and is positioned after the flue gas cooling device at the smelting furnace outlet. Its flue gas temperature is as high as 500°C or above, and the high-temperature flue gas heat exchanger is made of SS310. The low-temperature flue gas heat exchanger is positioned between the GGH heat exchanger and the afterburner, releasing heat from the high-temperature flue gas to heat the low-temperature flue gas. Its operating temperature is approximately 190°C-350°C, and its materials can also be SS316, SS304, or carbon steel.
[0009] Furthermore, the thermal oil pressurized circulation system is an integral skid-mounted module, including a pressure pump, a filter and a valve; the pressure pump is a high-temperature resistant thermal oil pump that needs to withstand temperatures above 350°C.
[0010] Furthermore, the medium and low temperature SCR denitrification system includes an SCR denitrification tower, which is provided with an ammonia supply system, an ammonia injection grid, a flue gas mixer, a rectifier grid, a soot blower and a medium and low temperature catalyst.
[0011] Furthermore, the medium and low temperature catalyst is arranged between the rectifying grid and the GGH heat exchanger, the active temperature is not higher than 230°C, and the medium and low temperature catalyst is a honeycomb, plate or corrugated plate structure.
[0012] Furthermore, the ammonia supply system includes an ammonia-air mixer, a dilution fan and an ammonia spray grid. The flue gas used to dilute the ammonia is taken from the clean flue gas after the induced draft fan. After the clean flue gas is pressurized by the dilution fan, it is diluted and mixed with ammonia through the ammonia-air mixer. The diluted ammonia is sprayed into the flue through the ammonia spray grid.
[0013] Furthermore, the diluted ammonia is fully mixed with the flue gas by the mixer, and the mixed gas is rectified by the rectifier grid before entering the medium- and low-temperature catalyst. Preferably, the diluted ammonia injected into the flue gas is fully mixed by the mixer, rectified by the rectifier, and then the flue gas passes vertically through the catalyst, where denitrification is completed.
[0014] Furthermore, the GGH heat exchange system includes a GGH heat exchanger and is arranged at the bottom of the SCR denitrification tower and forms an integral part of the denitrification tower. The high-temperature flue gas at the catalyst outlet is used to heat the low-temperature flue gas at the desulfurization tower outlet. The inlet and outlet of the SCR denitrification tower are both equipped with temperature measuring devices.
[0015] Furthermore, the burner is arranged between the low-temperature flue gas heat exchanger and the ammonia injection grid. Preferably, the burner is turned on and off according to the flue gas temperature at the outlet of the low-temperature flue gas heat exchanger and the flue gas temperature before entering the SCR catalyst to ensure the temperature required for SCR denitrification.
[0016] The utility model has the following beneficial effects:
[0017] Subject to the sulfur dioxide concentration in the flue gas after desulfurization (<100mg / Nm 3), the reaction temperature of the medium and low temperature SCR denitrification system needs to be controlled above 230°C, while the temperature of the flue gas after wet desulfurization is only 50°C-60°C. If only natural gas is used to heat the flue gas, the operating cost will be extremely high, which is unacceptable to the enterprise. Therefore, the utility model makes full use of the heat of the high-temperature flue gas section, adopts a thermal oil heat exchanger to recover the heat of the high-temperature flue gas section, and then releases the absorbed heat in the low-temperature flue gas section. The low-temperature flue gas is heated by the joint heating effect of the GGH heat exchanger and the thermal oil heat exchanger. For example, when the flue gas temperature at the outlet of the thermal oil heat exchanger is lower than 230°C, the natural gas burner is put into operation for supplementary heating, thereby ensuring that the flue gas temperature entering the SCR denitrification catalyst is higher than 230°C, completing denitrification, and ensuring that the pollutants in the enterprise's smelting kiln are discharged in a long-term and stable manner during normal production, which greatly saves the operating cost of the denitrification system.
[0018] The detailed structure of the present invention is further described below in conjunction with the accompanying drawings and specific implementation methods. BRIEF DESCRIPTION OF THE DRAWINGS
[0019] Figure 1 - is a schematic diagram of the structure of the utility model;
[0020] 1-Kiln, 2-Flue gas cooling device, 3-High-temperature flue gas heat exchanger, 4-Heat transfer oil pressurized circulation system, 5-Heat transfer oil expansion tank, 6-Dust removal system, 7-Wet desulfurization system, 8-GGH heat exchanger, 9-Low-temperature flue gas heat exchanger, 10-Burner, 11-Ammonia injection grid, 12-Flue gas mixer, 13-Ammonia-air mixer, 14-Rectifier grid, 15-Soot blower, 16-Catalyst, 17-Induced draft fan, 18-Dilution fan, 19-Chimney. DETAILED DESCRIPTION
[0021] As shown in the accompanying drawings: a medium- and low-temperature SCR flue gas denitrification device for a smelting furnace 1, including a thermal oil heat exchange system, a GGH heat exchange system, a burner 10 supplementary combustion system and a medium- and low-temperature SCR denitrification system. The medium- and low-temperature SCR denitrification system is sequentially provided with a GGH heat exchange system, a thermal oil heat exchange system and a burner 10 supplementary combustion system. The thermal oil heat exchange system includes a thermal oil heat exchanger. The heat of the high-temperature flue gas is transferred to the low-temperature flue gas through the thermal oil system. The entire system is controlled by the control system. A temperature testing device is provided at the front end of the burner 10 supplementary combustion system. When the flue gas temperature at the outlet of the thermal oil heat exchanger is below 230°C, the burner 10 supplementary combustion system is put into operation to perform temperature compensation on the flue gas to ensure that the flue gas temperature entering the SCR denitrification catalyst 16 is higher than 230°C.
[0022] This solution combines the heat transfer oil heat exchange system, the GGH heat exchange system and the burner 10 supplementary combustion system. The three coordinate and compensate for the flue gas temperature under the control of the control system. According to the specific situation of the flue gas temperature, the controller controls the burner 10 supplementary combustion system to compensate for the flue gas temperature, thereby reducing energy loss. When the temperature detected by the temperature testing equipment is lower than the set value, the control system automatically controls the operation of the burner 10 supplementary combustion system to compensate for the flue gas temperature, ensuring that the flue gas temperature entering the SCR denitrification catalyst 16 is higher than 230°C; the GGH heat exchange system will use the high-temperature flue gas at the outlet of the catalyst 16 to heat the low-temperature flue gas at the outlet of the desulfurization tower; then the flue gas heated by the GGH heat exchanger is heated and heated by the low-temperature heat exchanger. If the temperature after heat exchange is still lower than 230°C, the controller automatically controls the burner 10 supplementary combustion system to compensate for the flue gas temperature according to the temperature detection signal.
[0023] In this embodiment, the thermal oil heat exchange system is a closed system. To ensure safe operation, it is equipped with an explosion vent. The thermal oil heat exchange system also includes a thermal oil pressurized circulation system 4 and a thermal oil expansion tank 5. The thermal oil pressurized circulation system 4 is an integrated skid-mounted module, including a pressure pump, filter, and valves. The pressure pump is a high-temperature thermal oil pump that must withstand temperatures exceeding 350°C. The thermal oil heat exchanger includes a high-temperature flue gas heat exchanger 3 and a low-temperature flue gas heat exchanger 9. The high-temperature flue gas heat exchanger 3 and the low-temperature flue gas heat exchanger 9 are connected by the thermal oil pressurized circulation system 4, which is equipped with a thermal oil expansion tank 5. Preferably, the heat transfer oil pressurized circulation system 4 includes a heat transfer oil delivery pipe, a filter, a pressure pump and a valve. The high-temperature flue gas heat exchanger 3, the low-temperature flue gas heat exchanger 9 and the heat transfer oil expansion tank 5 are connected by a delivery pipe. The delivery pipe is provided with a valve, a filter and a pressure pump. The high-temperature flue gas heat exchanger 3 is arranged at the outlet of the high-temperature flue gas of the kiln 1, and the low-temperature flue gas heat exchanger 9 is arranged between the burner 10 and the GGH heat exchange system for heat exchange and temperature increase of the low-temperature flue gas.
[0024] More preferably, the high-temperature flue gas heat exchanger 3 is disposed after the flue gas cooling device 2 at the outlet of the smelting kiln 1, and the low-temperature flue gas heat exchanger 9 is disposed between the GGH heat exchanger 8 and the afterburner 10 to heat the low-temperature flue gas. Preferably, the high-temperature flue gas heat exchanger 3 is used to recover heat from the high-temperature flue gas and is disposed after the flue gas cooling device 2 at the outlet of the smelting kiln 1. The flue gas temperature is as high as 500°C or above, and the high-temperature flue gas heat exchanger 3 is made of SS310. The low-temperature flue gas heat exchanger 9 is disposed between the GGH heat exchanger 8 and the afterburner 10, releasing heat from the high-temperature flue gas to heat the low-temperature flue gas. The operating temperature is approximately 190°C-350°C, and the low-temperature flue gas heat exchanger 9 can also be made of SS316, SS304, or carbon steel.
[0025] In the embodiment, the medium-low temperature SCR denitration system includes an SCR denitration tower, which is equipped with an ammonia supply system, an ammonia injection grid 11, a flue gas mixer 12, a rectifying grid 14, a soot blower 15, and a medium-low temperature catalyst 16. Preferably, the medium-low temperature catalyst 16 is disposed between the rectifying grid 14 and the GGH heat exchanger 8, has an active temperature not exceeding 230°C, and has a honeycomb, plate, or corrugated plate structure. In the present embodiment, the medium-low temperature catalyst 16 has a honeycomb structure.
[0026] The ammonia supply system includes an ammonia-air mixer 13, a dilution fan 18 and an ammonia injection grid 11. The flue gas used to dilute the ammonia is taken from the clean flue gas after the induced draft fan 17. After the clean flue gas is pressurized by the dilution fan 18, it is diluted and mixed with ammonia through the ammonia-air mixer 13. The diluted ammonia is sprayed into the flue through the ammonia injection grid 11. Preferably, the diluted ammonia is fully mixed with the flue gas under the action of the mixer, and then rectified by the rectifying grid 14 before entering the medium and low temperature catalyst 16. The medium and low temperature catalyst 16 is provided with three layers, and a soot blower 15 is provided at the upper end of the catalyst 16 to reduce the accumulation of dust on the catalyst 16 and block the catalyst 16. Preferably, the diluted ammonia injected into the flue gas is fully mixed under the action of the mixer, and after being rectified by the rectifier, the flue gas passes vertically through the catalyst 16, and denitrification is completed under the action of the catalyst 16.
[0027] In the embodiment, the GGH heat exchange system includes a GGH heat exchanger 8 and is arranged at the bottom of the SCR denitrification tower and forms an integral part with the denitrification tower. The high-temperature flue gas at the outlet of the catalyst 16 is used to heat the low-temperature flue gas at the outlet of the desulfurization tower. The inlet and outlet of the SCR denitrification tower are both provided with temperature measuring devices; a chimney 19 is provided at the tail end of the flue gas outlet of the SCR denitrification tower, and an induced draft fan 17 is provided between the SCR denitrification tower and the chimney 19 to provide clean flue gas to the safety supply system.
[0028] In the embodiment, the burner 10 is disposed between the low-temperature flue gas heat exchanger 9 and the ammonia injection grid 11. Preferably, the burner 10 is turned on and off according to the flue gas temperature at the outlet of the low-temperature flue gas heat exchanger 9 and the flue gas temperature before entering the SCR catalyst 16, ensuring the temperature required for SCR denitration.
[0029] Due to the sulfur dioxide concentration in the flue gas after desulfurization (<100mg / Nm 3), the reaction temperature of the medium and low temperature SCR denitrification system needs to be controlled above 230°C, while the temperature of the flue gas after wet desulfurization is only 50°C-60°C. If only natural gas is used to heat the flue gas, the operating cost will be extremely high, which is unacceptable to the enterprise. Therefore, the utility model makes full use of the heat of the high-temperature flue gas section, adopts a thermal oil heat exchanger to recover the heat of the high-temperature flue gas section, and then releases the absorbed heat in the low-temperature flue gas section. The low-temperature flue gas is heated by the GGH heat exchanger 8 and the thermal oil heat exchanger. When the flue gas temperature at the outlet of the thermal oil heat exchanger is lower than 230°C, the natural gas burner 10 is put into operation for additional heating, thereby ensuring that the flue gas temperature entering the SCR denitrification catalyst 16 is higher than 230°C, completing denitrification, and ensuring that the pollutants in the enterprise's smelting kiln 1 are discharged in a long-term and stable manner during normal production, which greatly saves the operating cost of the denitrification system.
[0030] The above is a preferred embodiment of the present invention and the technical principles used therein. For those skilled in the art, any obvious changes such as equivalent transformations, simple replacements, etc. based on the technical solution of the present invention, without departing from the spirit and scope of the present invention, shall fall within the scope of protection of the present invention.
Claims
1. A medium-low temperature SCR flue gas denitrification device for a smelting furnace, comprising a thermal oil heat exchange system, a GGH heat exchange system, a burner supplementary combustion system, and a medium-low temperature SCR denitrification system, characterized in that: The medium and low temperature SCR denitrification system is provided with a GGH heat exchange system, a thermal oil heat exchange system and a burner supplementary combustion system in sequence. The thermal oil heat exchange system includes a thermal oil heat exchanger. The heat transfer from the high temperature flue gas to the low temperature flue gas is completed by the thermal oil. The entire system is controlled by the control system. The front end of the burner supplementary combustion system is provided with a temperature testing device. When the flue gas temperature at the outlet of the thermal oil heat exchanger is below 230°C, the burner supplementary combustion system is put into operation to perform temperature compensation on the flue gas to ensure that the flue gas temperature entering the SCR denitrification catalyst is higher than 230°C.
2. The medium-low temperature SCR flue gas denitrification device for a smelting furnace according to claim 1 is characterized in that: The thermal oil heat exchange system is a closed system, which also includes a thermal oil pressurized circulation system and a thermal oil expansion tank; the thermal oil heat exchanger includes a high-temperature flue gas heat exchanger and a low-temperature flue gas heat exchanger, and the high-temperature flue gas heat exchanger and the low-temperature flue gas heat exchanger are connected through the thermal oil pressurized circulation system, and the thermal oil pressurized circulation system is provided with a thermal oil expansion tank.
3. The medium-low temperature SCR flue gas denitrification device for a smelting furnace according to claim 2, characterized in that: The high-temperature flue gas heat exchanger is arranged after the flue gas cooling device at the outlet of the smelting furnace, and the low-temperature flue gas heat exchanger is arranged between the GGH heat exchanger and the afterburning burner to heat the flue gas in the low-temperature section.
4. The medium-low temperature SCR flue gas denitrification device for a smelting furnace according to claim 2 is characterized in that: The heat transfer oil pressurized circulation system is an integral skid-mounted module, including a pressure pump, a filter and a valve; the pressure pump is a high-temperature resistant heat transfer oil pump.
5. The medium-low temperature SCR flue gas denitrification device for a smelting furnace according to claim 1 is characterized in that: The medium and low temperature SCR denitration system includes an SCR denitration tower, which is equipped with an ammonia supply system, an ammonia injection grid, a flue gas mixer, a rectifier grid, a soot blower and a medium and low temperature catalyst.
6. The medium-low temperature SCR flue gas denitrification device for a smelting furnace according to claim 5, characterized in that: The medium and low temperature catalyst is arranged between the rectifying grid and the GGH heat exchanger, and the active temperature is not higher than 230°C. The medium and low temperature catalyst is a honeycomb, plate or corrugated plate structure.
7. The medium-low temperature SCR flue gas denitrification device for a smelting furnace according to claim 5, characterized in that: The ammonia supply system includes an ammonia-air mixer, a dilution fan and an ammonia spray grid. The flue gas used to dilute the ammonia is taken from the clean flue gas after the induced draft fan. After the clean flue gas is pressurized by the dilution fan, it is diluted and mixed with ammonia through the ammonia-air mixer. The diluted ammonia is sprayed into the flue through the ammonia spray grid.
8. The medium-low temperature SCR flue gas denitrification device for a smelting furnace according to claim 7, characterized in that: Under the action of the mixer, the diluted ammonia and the flue gas are fully mixed, and the mixed gas is rectified through the rectifying grid and then enters the medium and low temperature catalyst.
9. The medium-low temperature SCR flue gas denitrification device for a smelting furnace according to any one of claims 1 to 8, characterized in that: The GGH heat exchange system includes a GGH heat exchanger and is arranged at the bottom of the SCR denitrification tower and forms an integral part with the denitrification tower. The inlet and outlet of the SCR denitrification tower are both provided with temperature measuring devices.
10. The medium-low temperature SCR flue gas denitrification device for a smelting furnace according to any one of claims 1 to 8, characterized in that: The burner is arranged between the low-temperature flue gas heat exchanger and the ammonia injection grid.