Garbage power generation fly ash gasification desalting method

Abstract

The invention discloses a garbage power generation fly ash gasification desalting method. The method comprises the following steps: (1) melting in a plasma electric arc furnace to remove dioxin in fly ash; (2) combustible gas in the flue gas is fully burnt out in the secondary combustion chamber, and denitration is carried out at the same time; (3) cooling the waste heat boiler; (4) removing salt and SO2 in the flue gas in the desulfurization and desalination spray tower; (5) spraying active carbon particles to capture residual water-insoluble harmful substances in the flue gas; and (6) introducing the flue gas into a sinter plate dust remover for dust removal, and discharging the flue gas after dust removal into the atmosphere after reaching the standard. According to the principle that water mist is sprayed to cool gaseous salt into liquid salt and then dissolve the liquid salt into the water mist, the salt is firstly separated from the fly ash, so that the purity of the collected crystallized salt is high, the water consumption is greatly reduced, the energy consumption and the environmental pollution are reduced by adopting a spraying mode, the salt of the fly ash can be fully washed with water, and the water consumption is reduced. And then the dust is separated from the flue gas, and is discharged into the atmosphere after meeting the environmental protection requirement.

Description

Technical Field

[0001] The invention belongs to the technical field of renewable energy utilization, and in particular relates to a method for gasifying and desalting fly ash for 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 a waste-to-energy fly ash gasification and desalination method 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: a method for gasifying and desalting fly ash in 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) 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; (6) The flue gas is passed into the 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: the temperature of the secondary combustion chamber is controlled to 1100°C, the residence time of the flue gas in the secondary combustion chamber is more than 2S, and the H2 and CO combustible gases in the flue gas are fully burned. The heating source of the secondary combustion chamber adopts liquefied natural gas (LNG), and the consumption is about 124.5 Nm³ / h; an SNCR denitrification device is added in a suitable area in the secondary combustion chamber, and the SNCR denitrification device is sprayed with urea solution to reduce the NOx in the flue gas to N2 and CO2. The urea solution is prepared with urea granules as a reducing agent. The spraying amount of urea granules is about 2.66Kg / h.

[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 can generate about 970kg of steam for 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] In step (5), 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.

[0009] In step (6), 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.

[0010] 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.

[0011] 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.

[0012] 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.

[0013] 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.

[0014] 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.

[0015] 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 method greatly reduces the water consumption, energy consumption and environmental pollution, and the salt in the fly ash can be fully washed with water. Then the dust is separated from the flue gas and discharged into the atmosphere after meeting environmental protection requirements. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 It is a process flow chart of the present invention. DETAILED DESCRIPTION

[0017] The embodiments of the present invention are further described in detail below in conjunction with the accompanying drawings and examples.

[0018] like Figure 1 As shown, a method for gasifying and desalting fly ash for waste-to-energy power generation of the present invention comprises the following steps: (1) First, the fly ash is melted in a plasma arc furnace 1 to remove dioxins from the fly ash; the designed fly ash processing capacity of the plasma arc furnace 1 is 100t / d, and the flue gas volume is about 4000Nm³ / h. The flue gas outlet temperature of the plasma arc furnace 1 is about 600-800℃. After the fly ash is melted in the plasma arc furnace 1, the salt content in the flue gas is about 600kg, the NOx concentration is about 400mg / Nm³, and the SO2 concentration is about 600 mg / Nm³. The flue gas also contains a small amount of combustible gases such as H2 and CO; (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) 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; (6) The flue gas is passed into the plastic sintering 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.

[0019] The specific process of step (2) is as follows: the temperature of the secondary combustion chamber 2 is controlled to 1100°C, the residence time of the flue gas in the secondary combustion chamber 2 is more than 2S, the H2 and CO combustible gases in the flue gas are fully burned, the heating source of the secondary combustion chamber 2 adopts liquefied natural gas (LNG), and the consumption of liquefied natural gas is about 124.5 Nm³ / h; an SNCR denitrification device is added to a suitable area in the secondary combustion chamber 2, and the urea solution is sprayed by the SNCR denitrification device 6 to reduce the NOx in the flue gas to N2 and CO2. The urea solution is prepared by using urea granules as a reducing agent. The spraying amount of urea granules is about 2.66Kg / h.

[0020] In step (3), the high-temperature flue gas discharged from the secondary combustion chamber 2 after denitration has a temperature of 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 (not shown) used for salt crystallization.

[0021] In step (4), the flue gas discharged from the waste heat boiler 3 is passed into the desulfurization and desalination spray tower 4. The 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 spray device 7 and the second-stage spray device 8 are both 15t / h. The spraying water volume of the third-stage spray device 9 is about 2.75t / h. The water content of the flue gas after the three-stage water spray is supersaturated. The spray water fully absorbs and dissolves the salt in the flue gas, and the desalination efficiency is greater than 90%. The flue gas temperature at the outlet of the desulfurization and desalination spray tower 4 is about 81.4°C, the moisture content is about 48.34%, the salt content is about 60kg / h, and the dust concentration is about 8.8g / m³.

[0022] In step (5), the activated carbon particles are sprayed by installing 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 11 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.

[0023] In step (6), 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.

[0024] 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. A method for gasifying and desalting fly ash from garbage-to-energy plants, characterized in that: 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) 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; (6) The flue gas is passed into the 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 method for gasifying and desalting fly ash from garbage-to-energy 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 method for gasifying and desalting fly ash from garbage-to-energy according to claim 2, characterized in that: 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 method for gasifying and desalting fly ash from garbage-to-energy according to claim 3, characterized in that: 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 method for gasifying and desalting fly ash from garbage-to-energy according to claim 4, characterized in that: In step (5), 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.

6. The method for gasifying and desalting fly ash from garbage-to-energy according to claim 5, characterized in that: In step (6), 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.

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