Energy-saving and environment-friendly comprehensive treatment method for garbage power generation fly ash
Through plasma arc furnace melting, multi-stage spray desalination and activated carbon capture technology, the problems of water resource waste and pollution in waste power generation fly ash treatment have been solved, and efficient and environmentally friendly salt extraction and dust resource utilization have been achieved.
Patent Information
- Application Number
- CN202411592564.9
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-11-08
- Publication Date
- 2025-01-14
AI Technical Summary
The existing waste power fly ash treatment method consumes a lot of water resources, has high energy consumption and pollutes the environment, and the debris in the washed salt crystal cannot be effectively utilized.
The plasma arc furnace melting treatment is used to remove dioxins, the secondary combustion chamber is fully burned, the waste heat boiler is cooled and desalted by three-stage water spray, desulfurization neutralization and flocculation precipitation to improve the purity of salt, activated carbon captures harmful substances, and plastic burning plate The dust collector collects dust and resmels to reduce water and energy consumption.
It has achieved fly ash treatment with low water consumption, low energy consumption and pollution-free, improved the purity and resource utilization of salt crystals, and ensured that flue gas meets the standards for emissions.
Smart Images
Figure CN119303941A_ABST
Abstract
Description
Technical Field
[0001] The invention belongs to the technical field of renewable energy utilization, and specifically relates to an energy-saving and environment-friendly comprehensive treatment method for fly ash from garbage power generation. Background Art
[0002] At present, the fly ash produced by garbage power generation contains not only toxic and heavy metals, but also a large amount of sodium chloride and potassium chloride. When these fly ashes containing a large amount of sodium chloride and potassium chloride are used as resources, a large amount of water is often needed to fully wash the fly ash. The fly ash washing is to dissolve and extract the potassium, sodium and chlorine in the fly ash to make secondary by-industrial products. The washed fly ash (also known as dechlorinated fly ash) is sent to the cement kiln for high-temperature calcination, and the high temperature of the cement kiln is used to solidify and decompose heavy metals and dioxins. This fly ash washing treatment method has the following problems: first, the water consumption is huge, resulting in waste of water resources, high energy consumption, large subsequent sewage treatment volume, and great pollution to the environment; second, after the water dissolves the salt in the fly ash, it will also dissolve other harmful substances into the water. If the salt is further evaporated and crystallized, there will be a large amount of debris in the crystallized salt, and these crystallized salts cannot be used due to too many debris. Summary of the invention
[0003] In order to solve the above technical problems existing in the prior art, the present invention provides an energy-saving and environmentally friendly comprehensive treatment method for waste-to-energy fly ash with low water consumption, low energy consumption, no pollution and high salt crystal purity.
[0004] In order to solve the above technical problems, the present invention adopts the following technical solution: an energy-saving and environmentally friendly comprehensive treatment method for fly ash from garbage power generation, comprising the following steps: (1) Firstly, the fly ash is melted in a plasma arc furnace to remove dioxins from the fly ash; (2) The flue gas discharged from the plasma arc furnace is introduced into the secondary combustion chamber to fully burn the combustible gas in the flue gas and denitrify the flue gas at the same time; (3) The high-temperature flue gas discharged from the secondary combustion chamber after denitration is passed into the waste heat boiler for cooling; (4) The flue gas discharged from the waste heat boiler is passed into the desulfurization and desalination spray tower, where it is quickly cooled and the salt and SO2 in the flue gas are removed by three-stage water spraying; (5) The salt water settled in the desulfurization and desalination spray tower is discharged into the desulfurization neutralization tank and the flocculation sedimentation tank in turn, and finally the salt is crystallized out through the MVR evaporator; (6) Spraying activated carbon particles on the flue gas discharged from the desulfurization and desalination spray tower to capture the residual water-insoluble harmful substances in the flue gas; (7) The flue gas is passed into a plastic sintering plate dust collector for dust removal. The flue gas after dust removal is discharged into the atmosphere after meeting the standards. The collected particulate matter is sent to the plasma arc furnace of step (1) for further smelting treatment.
[0005] The specific process of step (2) is as follows: controlling the temperature of the secondary combustion chamber to 1100°C, the residence time of the flue gas in the secondary combustion chamber to be more than 2S, and fully burning the H2 and CO combustible gases in the flue gas. The heating source of the secondary combustion chamber adopts liquefied natural gas; adding an SNCR denitrification device in a suitable area of the secondary combustion chamber, and spraying urea solution through the SNCR denitrification device to reduce NOx in the flue gas to N2 and CO2. The urea solution is prepared by using urea granules as a reducing agent.
[0006] In step (3), the high-temperature flue gas discharged from the secondary combustion chamber after denitration has a temperature of 1100°C. After entering the waste heat boiler, the flue gas temperature drops to 800°C. The hot steam generated by the waste heat boiler is used in the MVR evaporator used for salt crystallization.
[0007] In step (4), the flue gas discharged from the waste heat boiler is passed into the desulfurization and desalination spray tower. A three-stage water spray device is arranged in the desulfurization and desalination spray tower. The first-stage water spray device rapidly reduces the flue gas temperature to 81°C-82°C. The spraying water volume of the first-stage spray device and the second-stage spray device are both 15 t / h. The spraying water volume of the third-stage spray device is about 2.75 t / h. The water content of the flue gas after the three-stage water spray is supersaturated, and the moisture content of the flue gas is 48.34%. The spray water fully absorbs and dissolves the salt in the flue gas, and the desalination efficiency is greater than 90%.
[0008] The specific process of step (5) is as follows: the salt water settled in the desulfurization and desalination spray tower first passes through the desulfurization neutralization tank, and sodium hydroxide solution is added to the desulfurization neutralization tank to neutralize the acidic spray water and fix the sulfate in the water; a reverse osmosis membrane is provided inside the flocculation sedimentation tank to divide the inside of the flocculation sedimentation tank into a concentration side and a purification side, and the neutralized salt solution is discharged into the concentration side of the flocculation sedimentation tank, and a flocculant is added to the concentration side to precipitate water-insoluble impurities. The salt water initially filtered on the concentration side is concentrated by 6 times through the reverse osmosis membrane, and the concentrated brine is then discharged into the MVR evaporator to crystallize salt. The water evaporated by the MVR evaporator passes through the condenser to generate condensate, and the condensate is injected into the concentration side as flushing water. The hot steam after heat exchange in the waste heat boiler provides heat energy for the MVR evaporator, and the water discharged from the purification side is used as spray water for the first-stage spray device and the second-stage spray device. The third-stage spray device uses tap water to supplement the circulating water.
[0009] In step (6), the activated carbon particles are sprayed by installing a gas-solid separation device on the smoke conveying pipeline between the desulfurization and desalination spray tower and the plastic-sintered plate dust collector. The activated carbon injection system sprays the activated carbon particles into the gas-solid separation device. The gas-solid separation device separates the captured water-insoluble harmful substances from the flue gas, and the flue gas is discharged into the plastic-sintered plate dust collector.
[0010] In step (7), more than 99% of the dust particles are collected after the flue gas passes through the plastic sintering plate dust collector, and the collected particles are sent to the plasma arc furnace of step (1) for further smelting treatment. The flue gas after dust removal is tested and the particle concentration is less than 10 mg / Nm³ before it meets the emission standards.
[0011] By adopting the above technical solution, compared with the prior art, the present invention has the following technical effects: 1) The fly ash produced by waste-to-energy is first melted in a plasma arc furnace to fully decompose the dioxins in the fly ash, thereby making the fly ash a resource.
[0012] 2) The secondary combustion in the secondary combustion chamber increases the flue gas temperature, which can fully burn out the combustible gases such as H2 and CO in the flue gas, and at the same time reduce the NOx in the flue gas to harmless gases such as N2 and CO2.
[0013] 3) The flue gas enters the waste heat boiler for heat exchange, and the heat of the flue gas is utilized, while the temperature of the flue gas is reduced. After the temperature is reduced, the flue gas enters the desulfurization and desalination spray tower. The liquefaction temperature of the salt is about 800°C. The first-stage spray device in the desulfurization and desalination spray tower quickly cools the flue gas. The gaseous salt is fully dissolved by the water mist and then enters the high-temperature evaporation and crystallization equipment. The water mist sprayed by the second-stage spray device and the third-stage spray device further dissolves the salt in the flue gas to ensure that the salt in the flue gas is basically absorbed.
[0014] 4) After the flue gas is cooled and sprayed for desalination, it is sprayed with activated carbon particles to capture harmful particulate matter that is insoluble in water.
[0015] 5) The plastic plate sintering dust collector removes and collects the dust dissolved in water and then sends it to the plasma arc furnace for further smelting treatment, ensuring that all fly ash is recycled after treatment and the flue gas that meets the standards is discharged into the atmosphere.
[0016] 6) The plastic plate sintering dust collector removes and collects the dust dissolved in water and then sends it to the plasma arc furnace for further smelting treatment, ensuring that all fly ash is recycled after treatment and the flue gas that meets the standards is discharged into the atmosphere.
[0017] 7) The spray water of dissolved and cooled liquefied salts is first discharged into the desulfurization neutralization tank for neutralization with alkali solution, and the sulfur ions in the solution are converted into sulfate ions, and then discharged into the flocculation sedimentation tank to precipitate the impurities insoluble in water after neutralization, thereby improving the purity of the salt in the brine. The reverse osmosis membrane set at the same time plays the role of concentrating the brine. The light brine with less salt content enters the clean water side through the reverse osmosis membrane. The water in the clean water side is used for spraying the first-stage spray device and the second-stage spray device. The water evaporated by the MVR evaporator passes through the condenser to generate condensed water, which is then injected into the concentration side as flushing water, and the hot steam after heat exchange of the waste heat boiler provides heat energy for the MVR evaporator. The recycling of these water vapor and water fully reduces the water consumption and also reduces the production cost.
[0018] In summary, the present invention adopts the principle of spraying water mist to cool gaseous salt and then dissolve it into liquid salt in the water mist. The salt is first separated from the fly ash, which can ensure the high purity of the crystallized salt after collection. The spray cooling and salt dissolving method greatly reduces the water consumption, reduces energy consumption and environmental pollution, and can fully wash the salt of the fly ash. Then, the dust is separated from the flue gas and discharged into the atmosphere after meeting environmental protection requirements. The salt separated from the flue gas is crystallized into high-purity salt after neutralization, flocculation and reverse osmosis as industrial salt. However, the salt contains sodium chloride and potassium chloride, which can be further separated and utilized. BRIEF DESCRIPTION OF THE DRAWINGS
[0019] Figure 1 It is a process flow chart of the present invention. DETAILED DESCRIPTION
[0020] The embodiments of the present invention are further described in detail below in conjunction with the accompanying drawings and examples.
[0021] like Figure 1 As shown, the present invention provides an energy-saving and environment-friendly comprehensive treatment method for fly ash from garbage power generation, comprising the following steps: (1) Firstly, the fly ash is melted in a plasma arc furnace 1 to remove dioxins from the fly ash; (2) The flue gas discharged from the plasma arc furnace 1 is introduced into the secondary combustion chamber 2 to fully burn the combustible gas in the flue gas and denitrate the flue gas at the same time; (3) The high-temperature flue gas after denitration discharged from the secondary combustion chamber 2 is passed into the waste heat boiler 3 for cooling; (4) The flue gas discharged from the waste heat boiler 3 is passed into the desulfurization and desalination spray tower 4, where it is quickly cooled down and the salt and SO2 in the flue gas are removed by three-stage water spraying; (5) The salt water settled in the desulfurization and desalination spray tower 4 is discharged into the desulfurization neutralization tank 13 and the flocculation sedimentation tank 14 in sequence, and finally the salt is crystallized out through the MVR evaporator 15; (6) Spraying activated carbon particles on the flue gas discharged from the desulfurization and desalination spray tower 4 to capture the water-insoluble harmful substances remaining in the flue gas; (7) The flue gas is passed into the sintered plate dust collector 5 for dust removal. The flue gas after dust removal is discharged into the atmosphere after meeting the standards. The collected particulate matter is sent to the plasma arc furnace 1 of step (1) for further smelting treatment.
[0022] The specific process of step (2) is as follows: controlling the temperature of the secondary combustion chamber 2 to 1100°C, the residence time of the flue gas in the secondary combustion chamber 2 to be more than 2S, and fully burning out the H2 and CO combustible gases in the flue gas. The heating source of the secondary combustion chamber 2 adopts liquefied natural gas; adding an SNCR denitrification device 6 in a suitable area in the secondary combustion chamber 2, and spraying urea solution through the SNCR denitrification device 6 to reduce NOx in the flue gas to N2 and CO2. The urea solution is prepared by using urea granules as a reducing agent.
[0023] In step (3), the temperature of the high-temperature flue gas discharged from the secondary combustion chamber 2 after denitration is 1100°C. After entering the waste heat boiler 3, the flue gas temperature drops to 800°C. The hot steam generated by the waste heat boiler 3 is used in the MVR evaporator 15 used for salt crystallization.
[0024] In step (4), the flue gas discharged from the waste heat boiler 3 is passed into the desulfurization and desalination spray tower 4. A three-stage water spray device is arranged in the desulfurization and desalination spray tower 4. The first-stage water spray device 7 rapidly reduces the flue gas temperature to 81°C-82°C. The spraying water volume of the first-stage water spray device 7 and the second-stage water spray device 8 are both 15 t / h. The spraying water volume of the third-stage water spray device 9 is about 2.75 t / h. The water content of the flue gas after the three-stage water spray is in an oversaturated state, and the moisture content of the flue gas is 48.34%. The spray water fully absorbs and dissolves the salt in the flue gas, and the desalination efficiency is greater than 90%.
[0025] The specific process of step (5) is as follows: the salt water precipitated from the desulfurization and desalination spray tower 4 first passes through the desulfurization neutralization tank 13, and a sodium hydroxide solution is added to the desulfurization neutralization tank 13 to neutralize the acidic spray water and fix the sulfate in the water; a reverse osmosis membrane 16 is provided inside the flocculation sedimentation tank 14 to separate the inside of the flocculation sedimentation tank 14 into a concentration side 17 and a purification side 18, and the neutralized salt solution is discharged into the concentration side 17 of the flocculation sedimentation tank 14, and a flocculant is added to the concentration side 17 to precipitate water-insoluble impurities, and the salt water ( The salt water (with a salt concentration of about 2%) is concentrated by 6 times to 12% salt water through a reverse osmosis membrane 16, and the concentrated salt water is then discharged into the MVR evaporator 15 to crystallize out salt. The water evaporated by the MVR evaporator 15 passes through the condenser 19 to generate condensed water, which is then injected into the concentration side 17 as flushing water. The hot steam after heat exchange in the waste heat boiler 3 provides thermal energy for the MVR evaporator 15. The water discharged from the purification side 18 is used as the spray water of the first-stage water spray device 7 and the second-stage spray device 8. The third-stage spray device 9 uses tap water to supplement the circulating water.
[0026] In step (6), the activated carbon particles are sprayed by setting a gas-solid separation device 10 on the smoke conveying pipeline between the desulfurization and desalination spray tower 4 and the plastic-sintered plate dust collector 5. The activated carbon injection system sprays the activated carbon particles into the gas-solid separation device 10. The gas-solid separation device 10 separates the captured water-insoluble harmful substances from the flue gas, and the flue gas is discharged into the plastic-sintered plate dust collector 5.
[0027] In step (7), after the flue gas passes through the plastic sintering plate dust collector 5, more than 99% of the dust particles are collected, and the collected particles are sent to the plasma arc furnace 1 in step (1) for further smelting treatment. After the flue gas after dust removal is tested, the particle concentration is less than 10 mg / Nm³ and then it is discharged through the chimney 12 to meet the emission standards.
[0028] The above embodiments illustrate the basic principles and features of the present invention, but the above only illustrates the preferred embodiments of the present invention and is not limited to the embodiments. Under the inspiration of this patent, a person skilled in the art can make many forms of deformation and improvement without departing from the scope of protection of the present invention and the claims, which are all within the protection scope of the present invention. Therefore, the patent and protection scope of the present invention shall be subject to the attached claims.
Claims
1. An energy-saving and environment-friendly comprehensive treatment method for fly ash from garbage power generation, characterized by: The following steps are involved: (1) Firstly, the fly ash is melted in a plasma arc furnace to remove dioxins from the fly ash; (2) The flue gas discharged from the plasma arc furnace is introduced into the secondary combustion chamber to fully burn the combustible gas in the flue gas and denitrify the flue gas at the same time; (3) The high-temperature flue gas discharged from the secondary combustion chamber after denitration is passed into the waste heat boiler for cooling; (4) The flue gas discharged from the waste heat boiler is passed into the desulfurization and desalination spray tower, where it is quickly cooled and the salt and SO2 in the flue gas are removed by three-stage water spraying; (5) The salt water settled in the desulfurization and desalination spray tower is discharged into the desulfurization neutralization tank and the flocculation sedimentation tank in turn, and finally the salt is crystallized out through the MVR evaporator; (6) Spraying activated carbon particles on the flue gas discharged from the desulfurization and desalination spray tower to capture the residual water-insoluble harmful substances in the flue gas; (7) The flue gas is passed into a plastic sintering plate dust collector for dust removal. The flue gas after dust removal is discharged into the atmosphere after meeting the standards. The collected particulate matter is sent to the plasma arc furnace of step (1) for further smelting treatment.
2. The energy-saving and environment-friendly comprehensive treatment method for fly ash from garbage-to-energy power generation according to claim 1, characterized in that: The specific process of step (2) is as follows: controlling the temperature of the secondary combustion chamber to 1100°C, the residence time of the flue gas in the secondary combustion chamber to be more than 2S, and fully burning the H2 and CO combustible gases in the flue gas. The heating source of the secondary combustion chamber adopts liquefied natural gas; adding an SNCR denitrification device in a suitable area of the secondary combustion chamber, and spraying urea solution through the SNCR denitrification device to reduce NOx in the flue gas to N2 and CO2. The urea solution is prepared by using urea granules as a reducing agent.
3. The energy-saving and environment-friendly comprehensive treatment method for fly ash from garbage-to-energy power generation according to claim 2 is characterized by: In step (3), the high-temperature flue gas discharged from the secondary combustion chamber after denitration has a temperature of 1100°C. After entering the waste heat boiler, the flue gas temperature drops to 800°C. The hot steam generated by the waste heat boiler is used in the MVR evaporator used for salt crystallization.
4. The energy-saving and environment-friendly comprehensive treatment method for fly ash from garbage-to-energy power generation according to claim 3 is characterized by: In step (4), the flue gas discharged from the waste heat boiler is passed into the desulfurization and desalination spray tower. A three-stage water spray device is arranged in the desulfurization and desalination spray tower. The first-stage water spray device rapidly reduces the flue gas temperature to 81°C-82°C. The spraying water volume of the first-stage spray device and the second-stage spray device are both 15 t / h. The spraying water volume of the third-stage spray device is about 2.75 t / h. The water content of the flue gas after the three-stage water spray is supersaturated, and the moisture content of the flue gas is 48.34%. The spray water fully absorbs and dissolves the salt in the flue gas, and the desalination efficiency is greater than 90%.
5. The energy-saving and environment-friendly comprehensive treatment method for fly ash from garbage-to-energy power generation according to claim 4 is characterized by: The specific process of step (5) is as follows: the salt water settled in the desulfurization and desalination spray tower first passes through the desulfurization neutralization tank, and sodium hydroxide solution is added to the desulfurization neutralization tank to neutralize the acidic spray water and fix the sulfate in the water; a reverse osmosis membrane is provided inside the flocculation sedimentation tank to divide the inside of the flocculation sedimentation tank into a concentration side and a purification side, and the neutralized salt solution is discharged into the concentration side of the flocculation sedimentation tank, and a flocculant is added to the concentration side to precipitate water-insoluble impurities. The salt water initially filtered on the concentration side is concentrated by 6 times through the reverse osmosis membrane, and the concentrated brine is then discharged into the MVR evaporator to crystallize salt. The water evaporated by the MVR evaporator passes through the condenser to generate condensate, and the condensate is injected into the concentration side as flushing water. The hot steam after heat exchange in the waste heat boiler provides heat energy for the MVR evaporator, and the water discharged from the purification side is used as the spray water of the first-stage spray device and the second-stage spray device. The third-stage spray device uses tap water to supplement the circulating water.
6. The energy-saving and environment-friendly comprehensive treatment method for fly ash from garbage-to-energy power generation according to claim 4 is characterized by: In step (6), the activated carbon particles are sprayed by installing a gas-solid separation device on the smoke conveying pipeline between the desulfurization and desalination spray tower and the plastic-sintered plate dust collector. The activated carbon injection system sprays the activated carbon particles into the gas-solid separation device. The gas-solid separation device separates the captured water-insoluble harmful substances from the flue gas, and the flue gas is discharged into the plastic-sintered plate dust collector.
7. The energy-saving and environment-friendly comprehensive treatment method for fly ash from garbage-to-energy power generation according to claim 6 is characterized by: In step (7), more than 99% of the dust particles are collected after the flue gas passes through the plastic sintering plate dust collector, and the collected particles are sent to the plasma arc furnace of step (1) for further smelting treatment. The flue gas after dust removal is tested and the particle concentration is less than 10 mg / Nm³ before it meets the emission standards.