Energy-saving and efficient multi-stage collaborative deacidification system for waste incinerator

Abstract

The application discloses an energy-saving and efficient multi-stage collaborative deacidification system of a waste incinerator, relates to the technical field of deacidification treatment of the waste incinerator, and discloses a three-stage deacidification collaborative waste heat utilization method, which comprises the following steps: introducing calcium carbonate dry powder into the waste incinerator through the secondary air hole, introducing high-activity lime dry powder into the waste incinerator, recovering waste heat of flue gas at the outlet of the economizer, and performing semi-dry treatment in a reaction tower, and the three-stage deacidification collaborative waste heat utilization method is matched with a powder spraying gun with high mixing effect, so that the original flue gas concentration entering the reaction tower can be greatly reduced, the deacidification material cost is reduced, the amount of fly ash generated is greatly reduced, waste heat of flue gas is recovered, the flue gas temperature at the outlet of the reaction tower is increased, and the corrosion of the tail flue is reduced. In addition, through the three-stage deacidification collaborative waste heat recovery, the energy utilization rate is improved, the flue gas temperature at the outlet of the reaction tower is increased, the corrosion of the tail flue is reduced, the air leakage rate and the power consumption of the fan are reduced, and long-period economic and stable operation is ensured.

Description

Technical Field

[0001] This application relates to the technical field of acid removal treatment in waste incinerators, and in particular to an energy-saving and efficient multi-stage synergistic acid removal system for waste incinerators. Background Technology

[0002] Currently, the main acidic substances in the flue gas from waste incinerators are SO2 and HCl. The mainstream flue gas desulfurization process is a combination of semi-dry and dry desulfurization processes. A few furnaces use pure dry desulfurization, while a few others are equipped with wet desulfurization processes due to strict emission restrictions.

[0003] In related technologies, semi-dry acid removal typically uses CaO or Ca(OH)₂ to form a lime slurry suspension with a density of 10-16%. This slurry is atomized into fine droplets by a rotary atomizer and sprayed into a reaction tower for gas / liquid and solid / liquid phase acid-base neutralization reactions. Dry acid removal, on the other hand, involves directly injecting Ca(OH)₂ into the flue gas duct, where it reacts with acidic substances in the flue gas in a solid / gas phase acid-base neutralization reaction. Because the gas / liquid reaction is more efficient, most waste incineration projects are equipped with reaction towers primarily using semi-dry acid removal, with dry acid removal as a backup.

[0004] Furthermore, most waste-to-energy plants in the industry suffer from excessive injection of desulfurizing agents and low utilization rates of these agents in their flue gas desulfurization processes. When the waste composition is too complex, the original concentration of flue gas is high, and it exceeds the optimal efficiency range of the reaction tower, excessive lime slurry needs to be added to the reaction tower to significantly increase the calcium-sulfur ratio in order to control the indicators.

[0005] Regarding the aforementioned technologies, the inventors believe that: when supplementing control indicators through dry methods, the lower efficiency of dry methods also leads to waste of environmental protection materials and increases the cost of flue gas desulfurization; simultaneously, to ensure emission compliance, excessive lime slurry is often injected, which can easily cause the flue gas temperature at the reaction tower outlet to be too low, resulting in low-temperature corrosion and air leakage in subsequent bag filters and flue gas pipelines, leading to increased flue gas flow, which is extremely detrimental to the total amount of pollutant emissions and the power consumption of induced draft fans; furthermore, to ensure sufficient slurry injection margin, the outlet flue gas temperature must be controlled at a high level at the economizer outlet, causing significant heat loss in the flue gas and reducing boiler efficiency; in addition, excessive lime will eventually enter the fly ash and become a component of the fly ash, increasing the amount of fly ash and the subsequent fly ash treatment cost; secondly, to ensure the flue gas outlet temperature, the slurry density can be increased, but higher density slurry injected into the reaction tower increases the probability of atomizer failure, increases maintenance workload, and also easily causes ash accumulation and wall adhesion on the inner wall of the tower, seriously affecting normal operation. Utility Model Content

[0006] The purpose of this application is to provide an energy-efficient and high-performance multi-stage synergistic acid removal system for waste incinerators. This addresses the issue that when control indicators are supplemented via dry methods, the lower efficiency of the dry method leads to waste of environmentally friendly materials and increases the cost of flue gas acid removal. Furthermore, to ensure emission compliance, excessive injection of lime slurry often results in low flue gas temperature at the reaction tower outlet, causing low-temperature corrosion and air leakage in subsequent baghouse dust collectors and flue gas ducts, leading to increased flue gas flow. This is extremely detrimental to both total pollutant emissions and induced draft fan power consumption. Additionally, to ensure adequate filling... The excessive amount of slurry injected necessitates maintaining a high flue gas temperature at the economizer outlet, resulting in significant heat loss and reduced boiler efficiency. Furthermore, excess lime ultimately contributes to fly ash, increasing its volume and subsequent treatment costs. Secondly, while increasing slurry density can maintain flue gas outlet temperature, higher density slurry injected into the reaction tower increases the probability of atomizer malfunctions, requiring more maintenance. It also easily leads to ash accumulation and buildup on the tower walls, severely impacting normal operation.

[0007] On the one hand, the energy-saving and efficient multi-stage synergistic desulfurization process for a waste incinerator provided in this application adopts the following technical solution: An energy-efficient and high-performance multi-stage synergistic acid removal process for waste incinerators includes the following steps: S1. In-furnace calcium carbonate deacidification: By using a calcium carbonate spray gun to spray calcium carbonate into the secondary air position of the incinerator, acidic gases are removed in one step to reduce the original concentration of flue gas entering the waste heat boiler. S2. In-furnace high-activity lime deacidification: The flue gas after primary removal flows backward under the drive of the induced draft fan. In the high-temperature zone of flue gas in the first channel of the boiler / after the evaporator in the third channel, high-activity lime is sprayed into the furnace through a lime spray gun to perform secondary removal of acidic gases, so as to further reduce the original concentration of flue gas entering the reaction tower. S3-1, Flue gas waste heat recovery: Under the premise of S1 and S2, the concentration of acidic gas in the flue gas at the economizer outlet is reduced to a low level, which has little impact on the corrosion of the tube bundle heat exchanger profile. Waste heat is recovered at the economizer outlet to make deep use of the flue gas waste heat and improve the overall thermal efficiency of the incinerator. S3-2, Semi-dry lime slurry deacidification: In the reaction tower, the original concentration of flue gas after two acid gas removal processes has been reduced to a low level and is in the semi-dry reaction zone. After entering the reaction tower, lime slurry is added for a final acid gas removal, which achieves environmental protection standards for safe emission and realizes stable control of the outlet flue gas temperature of the reaction tower.

[0008] Furthermore, a plurality of calcium carbonate spray guns are provided, and the plurality of calcium carbonate spray guns are evenly arranged and installed along the furnace of the incinerator, with an installation distance of 2.5m-3m between the plurality of calcium carbonate spray guns.

[0009] Furthermore, the spray velocity of the calcium carbonate spray gun is designed to be no less than 20 m / s, and the temperature at the injection point of the calcium carbonate spray gun is designed to be no less than 1050℃; the pressure of the secondary air in the incinerator should be maintained at no less than 600 Pa.

[0010] Furthermore, the nozzles of several of the calcium carbonate spray guns are all butterfly-shaped nozzles or multi-directional dispersion nozzles.

[0011] Furthermore, a plurality of lime spray guns are provided, and the plurality of lime spray guns are provided on the evaporator, and the nozzles of the plurality of lime spray guns are all butterfly-shaped nozzles or multi-directional dispersion nozzles.

[0012] Furthermore, the highly active lime contains various non-heavy metals, activators, modifiers, and dispersants.

[0013] On the other hand, the energy-saving and efficient multi-stage synergistic acid removal system for a waste incinerator provided in this application adopts the following technical solution: An energy-efficient and high-performance multi-stage synergistic desulfurization system for a waste incinerator includes an incinerator, an economizer, a reaction tower, and a bag filter. The outlet of the incinerator is connected to the inlet of the economizer, and a calcium carbonate injection device is provided on the furnace of the incinerator to facilitate the injection of dry calcium carbonate powder into the interior of the incinerator. An evaporator is provided between the outlet of the incinerator and the inlet of the economizer. A high-activity lime injection device is provided on the evaporator to facilitate the injection of high-activity lime dry powder into the interior of the evaporator. The outlet of the economizer is connected to the inlet of the reaction tower via a connecting flue, the outlet of the reaction tower is connected to the inlet of the filter bag, and the reaction tower stores lime slurry.

[0014] Furthermore, the incinerator is provided with a first flue, a second flue, and a third flue, which are connected sequentially. The outlet of the third flue is connected to the inlet of the economizer. The calcium carbonate injection device is installed on the first flue, the evaporator is installed in the third flue, and the highly active lime injection device is installed on the evaporator.

[0015] Furthermore, the calcium carbonate injection device includes several calcium carbonate spray guns disposed on the flue, and several secondary air holes are opened at the front wall of the furnace of the flue, and the nozzles of several calcium carbonate spray guns are respectively inserted into several secondary air holes. The high-activity lime spraying device includes several lime spray guns disposed on the evaporator. Several flue vents are opened on the outside of the evaporator, and the nozzles of the lime spray guns are respectively inserted into the flue vents.

[0016] Furthermore, it also includes a gas-water heat exchanger one and a gas-water heat exchanger two. The gas-water heat exchanger one is located at the connecting flue. A steam-air preheater and a primary air fan are also provided on one side of the incinerator. The output end of the steam-air preheater is connected to the first flue. The gas-water heat exchanger two is connected between the steam-air preheater and the gas-water heat exchanger one. The input end of the gas-water heat exchanger two is connected to the output end of the primary air fan.

[0017] Compared with the prior art, the beneficial effects of this application are as follows: This application proposes a three-stage deacidification and waste heat utilization method that combines secondary air vents for porous calcium carbonate powder injection in the incinerator, high-activity lime powder injection in the incinerator, waste heat recovery from the economizer outlet flue gas, and semi-dry treatment in the reaction tower. This method, combined with a powder spray gun with high mixing effect, can significantly reduce the concentration of the original flue gas entering the reaction tower. Consequently, it can reduce the cost of deacidification materials, significantly reduce fly ash generation, recover waste heat from the flue gas, increase the outlet flue gas temperature of the reaction tower, and mitigate corrosion of the tail flue.

[0018] In addition, by using three-stage deacidification and waste heat recovery, energy utilization efficiency is improved, the temperature of flue gas at the outlet of the reaction tower is increased, corrosion of the tail flue is reduced, and air leakage rate and fan power consumption are also reduced, ensuring long-term economic and stable operation.

[0019] In addition, by installing a gas-water heat exchanger one in the connecting flue between the economizer outlet and the reaction tower inlet, it is used to heat the intermediate medium; and by installing a gas-water heat exchanger two between the inlet of the steam-air preheater and the outlet of the gas-water heat exchanger one, it is used to heat the boiler's primary air with the heat of the heated intermediate medium, thereby ultimately realizing the recovery of flue gas waste heat, reducing flue gas heat loss, and improving boiler thermal efficiency. Attached Figure Description

[0020] Figure 1 This is a schematic diagram of the structure of the energy-saving and efficient multi-stage synergistic deacidification system for a waste incinerator, as described in this application embodiment.

[0021] Figure 2 This application includes a flowchart of the flue gas waste heat utilization process.

[0022] Explanation of reference numerals in the attached figures: 1. Incinerator; 11. First flue; 12. Second flue; 13. Third flue; 14. Calcium carbonate spray gun; 15. Secondary air vent; 2. Economizer; 3. Reaction tower; 4. Bag filter; 5. Connecting flue; 51. Gas-water heat exchanger one; 6. Gas-water heat exchanger two; 7. Steam-air preheater; 8. Primary air fan; 9. Evaporator; 91. Lime spray gun; 92. Flue vent. Detailed Implementation

[0023] The following is in conjunction with the appendix Figure 1 and Figure 2 This application will be described in further detail.

[0024] On the one hand, this application discloses an energy-saving and efficient multi-stage synergistic desulfurization process for waste incinerators, referring to... Figure 1 and Figure 2 In this embodiment, the multi-stage synergistic deacidification process includes the following steps: S1. In-furnace calcium carbonate spraying for acid removal: Calcium carbonate is sprayed into the incinerator 1 using calcium carbonate spray guns 14 to remove acidic gases in one step, thereby reducing the original concentration of flue gas entering the waste heat boiler. Specifically, several calcium carbonate spray guns 14 are installed, evenly arranged along the furnace of the incinerator 1, with a distance of 2.5m-3m between them. This installation allows the calcium carbonate spray guns 14 to evenly spray dry calcium carbonate powder into the interior of the waste heat boiler, thereby ensuring uniform mixing of the dry calcium carbonate powder with the acidic gases.

[0025] Meanwhile, the jet velocity of these calcium carbonate spray guns 14 should be designed to be no less than 20 m / s to ensure that the gas mixed with the powder has a certain rigidity, allowing it to penetrate deep into the furnace and ensuring thorough mixing of the powder and flue gas. Furthermore, the temperature at the injection point of these calcium carbonate spray guns 14 should be designed to be no less than 1050℃. This temperature design can improve the decomposition rate and deacidification effect of calcium carbonate.

[0026] In addition, the secondary air pressure in the incinerator should be maintained at no less than 600 Pa. This enhances the turbulence of the flue gas within the furnace, promotes better mixing, and improves reaction efficiency. Furthermore, calcium carbonate is inexpensive and produces virtually no fly ash during the deacidification process, effectively reducing costs associated with the deacidification stage.

[0027] Preferably, the nozzles of these calcium carbonate spray guns 14 are all butterfly-shaped nozzles or multi-directional dispersion nozzles; with such a setting, the powder gas at the nozzle can be effectively disturbed, thereby enhancing the mixing of powder and flue gas, and thus improving the primary removal effect of acidic gas.

[0028] S2. In-furnace deacidification with new type of high-activity lime: The flue gas after primary removal flows backward under the drive of the induced draft fan. After the high-temperature flue gas zone of the boiler channel 11 / evaporator 9 of the three channels 13, high-activity lime is sprayed into the furnace through lime spray gun 91 to perform secondary removal of acidic gas, so as to further reduce the original concentration of flue gas entering the reaction tower 3.

[0029] Specifically, several lime spray guns 91 are provided, and these lime spray guns 91 are respectively installed on the outside of the evaporator 9. The nozzles of these lime spray guns 91 are all butterfly-shaped nozzles or multi-directional dispersion nozzles. Through this arrangement, the powder gas at the nozzle can be effectively disturbed, thereby enhancing the mixing of powder and flue gas, maximizing the reaction efficiency of highly active lime, and thus improving the secondary removal effect of acidic gases.

[0030] Meanwhile, in step S2, the highly active lime sprayed into the evaporator 9 using the lime spray gun 91 contains various non-heavy metals, activators, modifiers, and inhibitors and dispersants, etc. It has the characteristics of dispersing (anti-adhesion), activating, corrosion inhibition, and polar adsorption. It has a high reaction rate with high concentrations of HCl, SO2, and HF. A small amount of highly active lime can significantly reduce the concentration of acidic gases, thereby greatly reducing the amount of slurry sprayed into the subsequent reaction tower 3. This increases the flue gas outlet temperature of the reaction tower 3 while significantly reducing the generation of fly ash.

[0031] S3-1, Flue Gas Waste Heat Recovery: Under the premise of S1 and S2, the concentration of acidic gas in the flue gas at the economizer 2 outlet is reduced to a low level, which has little impact on the corrosion of the tube bundle heat exchanger profile. Waste heat is recovered at the economizer 2 outlet to make deep use of the flue gas waste heat and improve the overall thermal efficiency of the incinerator.

[0032] Specifically, after the two-stage deacidification process (S1 and S2), the original concentration of acidic gases in the flue gas has been reduced to a low level. The designed flue gas heat exchange temperature is far above the acid dew point, which can effectively prevent low-temperature acid corrosion. By utilizing waste heat, the exhaust gas loss is reduced. After heating the hot water, the primary and secondary air are heated through the gas-water heat exchanger, which can effectively increase the primary air temperature and save the steam consumption of the steam-air preheater 7. The saved heating steam can continue to be used for the turbine to generate electricity, thereby improving the overall thermal efficiency of the incinerator.

[0033] S3-2, Semi-dry lime slurry deacidification: In reaction tower 3, the original concentration of flue gas after two acid gas removal processes has been reduced to a low level, which is in the optimal high-efficiency reaction range of the semi-dry process. After entering reaction tower 3, only a small amount of lime slurry needs to be added for a final acid gas removal to achieve safe emission of environmental protection standards and realize stable control of the outlet flue gas temperature of reaction tower 3.

[0034] Specifically, for an initial SO2 concentration < 350 mg / Nm³ 3 In this waste incineration project, reaction tower 3 can essentially discharge the slurry, requiring only water spraying for cooling. Simultaneously, due to the significant reduction in the original flue gas concentration and the substantial decrease in slurry injection volume, the outlet flue gas temperature of reaction tower 3 can be increased to 170℃-180℃ without affecting the desulfurization effect. Furthermore, the increased flue gas temperature of 20-40℃ can be used for waste heat recovery from the flue gas, used to heat the primary air or demineralized water, thus improving the overall plant thermal efficiency and creating greater value.

[0035] On the other hand, this application also provides an energy-efficient and high-performance multi-stage synergistic desulfurization system for waste incinerators, referring to... Figure 2 In this embodiment, the multi-stage synergistic deacidification system includes an incinerator 1, an economizer 2, a reaction tower 3, and a bag filter 4. The outlet of the incinerator 1 is connected to the inlet of the economizer 2, and a calcium carbonate injection device is installed on the furnace of the incinerator 1. This device facilitates the injection of dry calcium carbonate powder into the interior of the incinerator 1, allowing the calcium carbonate powder to remove acidic gases from the interior of the incinerator 1 in a single step, thereby reducing the original concentration of flue gas entering the economizer 2.

[0036] Specifically, refer to Figure 2 In this embodiment, the incinerator 1 is equipped with a first flue 11, a second flue 12, and a third flue 13. These three flues are sequentially connected, and the outlet of the third flue 13 is connected to the inlet of the economizer 2. The calcium carbonate injection device is located on the outside of the first flue 11. Specifically, the flue gas and calcium carbonate powder pass through the primary air in the incinerator 1 sequentially through the first flue 11, second flue 12, and third flue 13. This allows the calcium carbonate powder sufficient time to mix thoroughly with the acidic gases in the flue gas, effectively removing the acidic gases.

[0037] More specifically, the calcium carbonate injection device includes several calcium carbonate spray guns 14 installed on the outside of a flue 11, and several secondary air holes 15 are opened at the front wall of the furnace of the flue 11. The nozzles of the calcium carbonate spray guns 14 are respectively inserted into the secondary air holes 15, so that the calcium carbonate spray guns 14 are evenly arranged along the width of the furnace to ensure that the calcium carbonate spray guns 14 evenly spray calcium carbonate dry powder into the incinerator 1.

[0038] At the same time, refer to Figure 2In this embodiment, the outlet of the economizer 2 and the inlet of the reaction tower 3 are connected to each other through a connecting flue 5, and an evaporator 9 is installed between the outlet of the incinerator 1 and the inlet of the economizer 2. The evaporator 9 is equipped with a high-activity lime injection device. By setting the high-activity lime injection device, it is easy to inject high-activity lime dry powder into the interior of the evaporator 9, so that the high-activity lime dry powder can perform secondary removal treatment on the acidic gas passing through the interior of the evaporator 9, thereby further reducing the original concentration of flue gas entering the reaction tower 3.

[0039] Specifically, in this embodiment, the high-activity lime spraying device includes several lime spray guns 91 installed on the outside of the evaporator 9, and several flue vents 92 are symmetrically opened on the outside of the evaporator 9. The nozzles of the lime spray guns 91 are respectively inserted into the flue vents 92, so that the lime spray guns 91 are evenly arranged along the outside of the evaporator 9, so as to ensure that the lime spray guns 91 evenly spray the high-activity lime dry powder into the evaporator 9.

[0040] Additionally, refer to Figure 2 In this embodiment, the outlet of the reaction tower 3 is connected to the inlet of the bag filter 4, and a small amount of lime slurry is stored in the reaction tower 3. When the flue gas that has undergone two acid gas removal processes is discharged into the reaction tower 3, the original concentration of the flue gas has been reduced to a low level, which is within the optimal high-efficiency reaction range of the semi-dry method. In this way, the flue gas and the small amount of lime slurry in the reaction tower 3 undergo a final acid gas removal process, thereby achieving safe emission in accordance with environmental protection standards and realizing stable control of the flue gas temperature at the outlet of the reaction tower 3. Finally, the slurry in the reaction tower 3 is discharged into the bag filter 4 for collection, and then the slurry is processed uniformly in the future.

[0041] In addition, refer to Figure 1 and Figure 2 In this embodiment, a gas-water heat exchanger 51 and a second gas-water heat exchanger 6 are also included. The first gas-water heat exchanger 51 is installed at the connection point of the flue duct 5 and is located between the outlet of the economizer 2 and the inlet of the reaction tower 3, for heating the intermediate medium; specifically, the intermediate medium is water. A flue gas cooler is installed inside the first gas-water heat exchanger 51, which can cool the flue gas temperature from 220℃ to 165℃, recovering approximately 5231229 kJ / h of flue gas heat. The tubes of the flue gas cooler use closed-loop circulating demineralized water and are equipped with a demineralized water replenishment port to recover waste heat from the flue gas.

[0042] Meanwhile, a steam-air preheater 7 and a primary air fan 8 are also installed on one side of the incinerator 1. The output end of the steam-air preheater 7 is connected to a flue 11. The second gas-water heat exchanger 6 is installed on one side of the steam-air preheater 7 and is connected between the steam-air preheater 7 and the first gas-water heat exchanger 51. The second gas-water heat exchanger 6 and the first gas-water heat exchanger 51 are circulated together, so that the first gas-water heat exchanger 51 can transport the heated intermediate medium to the second gas-water heat exchanger 6, and the second gas-water heat exchanger 6 can also transport the intermediate medium back to the first gas-water heat exchanger 51, thereby realizing the circulatory transport of the intermediate medium.

[0043] This is a reference. Figure 2 In this embodiment, by installing a gas-water heat exchanger 51 on the connecting flue duct 5 at the outlet of the economizer 2, the flue gas can be cooled down, the waste heat in the flue gas can be recovered, and the closed-loop circulating water can be heated. The water medium flow rate is controlled by a variable frequency circulating pump. The water heated by the gas-water heat exchanger 51 has a specific temperature of 130°C. The 130°C hot water is then sent to the gas-water heat exchanger 6 to heat the primary air, thereby saving the steam required for heating the original primary air and improving the overall thermal efficiency.

[0044] Furthermore, the input end of the gas-water heat exchanger 26 is connected to the output end of the primary air fan 8. The output end of the primary air fan 8 discharges the primary air into the gas-water heat exchanger 26 for preliminary heating, and then into the steam-air preheater 7 for further heating. Finally, the hot air is discharged into the incinerator 1. In this way, the gas-water heat exchanger 26 is used to heat the boiler's primary air with the heat of the intermediate medium being heated, ultimately realizing the recovery of waste heat from the flue gas, reducing exhaust heat loss, and improving the boiler's thermal efficiency.

[0045] In this way, the waste heat utilization structure described above can reduce flue gas losses, heat the primary air, save the steam consumption of the steam-air preheater 7, and this part of the steam can be used to generate electricity by the steam turbine, which has good economic benefits.

[0046] Therefore, the multi-stage synergistic desulfurization process and system of this application involves a three-stage synergistic desulfurization method: calcium carbonate dry powder is introduced into the incinerator 1 through secondary air holes 15; highly active lime dry powder is introduced into the connecting flue 5 between the outlet of the incinerator 1 and the inlet of the economizer 2; and semi-dry treatment is carried out in the reaction tower 3. Combined with a powder spray gun with a high mixing effect, this method can significantly reduce the original flue gas concentration entering the reaction tower 3, thereby reducing the cost of desulfurization materials, significantly reducing fly ash generation, increasing flue gas temperature, recovering waste heat, and reducing the occurrence of tail flue corrosion.

[0047] In this process, calcium carbonate inside the furnace is the primary control method, while highly reactive lime outside the furnace serves as an auxiliary method. The semi-dry method is mainly used for temperature control and emergency situations (such as when HCl is too high or SO2 is extremely difficult to control). Specifically, taking a waste incineration project with an initial lime consumption of 12-15 kg / t as an example, the initial SO2 concentration of such projects is generally between 400-500 mg / Nm³. 3 The above describes the process. At this concentration, the calcium carbonate consumption in the furnace reaches 5 kg / t, which can essentially replace the acid removal effect of 5 kg / t ordinary lime in the original reaction tower, thus achieving a fly ash reduction of no less than 5 kg / t. However, the calcium carbonate consumption should not exceed 5 kg / t, otherwise it may easily cause other problems such as wear on the heated surfaces.

[0048] In the secondary deacidification stage outside the furnace, due to the extremely high reaction efficiency of highly active calcium hydroxide, 3-5 kg / t of highly active lime can basically control the indicators, thus further reducing fly ash production to some extent. In the tertiary deacidification stage, since the flue gas concentration is already very low, the slurry volume and concentration can be adjusted as supplementary control according to emission requirements, or the slurry can be withdrawn and only anti-thermal water added for temperature control. Since both primary and secondary deacidification use dry powder injection, the control effect on HCl is limited. When HCl levels are high, a highly efficient semi-dry emergency control method can be used. In special operating conditions with extremely high SO2 levels, a semi-dry emergency control method can also be employed.

[0049] This three-stage synergistic deacidification process increases the outlet flue gas temperature of reaction tower 3, recovers waste heat from the flue gas, and reduces corrosion of the tail flue, thereby reducing air leakage rate and fan power consumption, ensuring long-term economic and stable operation.

[0050] The above description is merely an embodiment of this utility model and does not limit the patent scope of this utility model. Any equivalent structural or procedural transformations made based on the description and drawings of this utility model, or direct or indirect applications in other related technical fields, are similarly included within the patent protection scope of this utility model.

Claims

1. An energy-efficient and high-performance multi-stage synergistic acid removal system for a waste incinerator, characterized in that: It includes an incinerator (1), an economizer (2), a reaction tower (3), and a filter bag (4); The outlet of the incinerator (1) is connected to the inlet of the economizer (2), and a calcium carbonate injection device is provided on the furnace of the incinerator (1) to facilitate the injection of dry calcium carbonate powder into the interior of the incinerator (1). An evaporator (9) is provided between the outlet of the incinerator (1) and the inlet of the economizer (2). A high-activity lime spraying device is provided on the evaporator (9) to facilitate the spraying of high-activity lime dry powder into the interior of the evaporator (9). The outlet of the economizer (2) is connected to the inlet of the reaction tower (3) via a connecting flue (5), the outlet of the reaction tower (3) is connected to the inlet of the cloth bag (4), and the reaction tower (3) stores lime slurry.

2. The energy-saving and efficient multi-stage synergistic acid removal system for a waste incinerator according to claim 1, characterized in that: The incinerator (1) is provided with a first flue (11), a second flue (12) and a third flue (13). The first flue (11), the second flue (12) and the third flue (13) are connected in sequence. The outlet of the third flue (13) is connected to the inlet of the economizer (2). The calcium carbonate injection device is set on the first flue (11). The evaporator (9) is set in the third flue (13). The high-activity lime injection device is set on the evaporator (9).

3. The energy-saving and efficient multi-stage synergistic acid removal system for a waste incinerator according to claim 2, characterized in that: The calcium carbonate injection device includes several calcium carbonate spray guns (14) disposed on the flue (11). Several secondary air holes (15) are provided at the front wall of the furnace of the flue (11). The nozzles of several calcium carbonate spray guns (14) are respectively inserted into several secondary air holes (15).

4. The energy-saving and efficient multi-stage synergistic acid removal system for a waste incinerator according to claim 3, characterized in that: The calcium carbonate spray gun (14) is provided in several units, and the several calcium carbonate spray guns (14) are evenly arranged and installed along the furnace of the incinerator (1), with the installation distance between the several calcium carbonate spray guns (14) being 2.5m-3m.

5. The energy-saving and efficient multi-stage synergistic deacidification system for a waste incinerator according to claim 3, characterized in that: The spray velocity of the calcium carbonate spray gun (14) is designed to be no less than 20 m / s, and the temperature of the injection point of the calcium carbonate spray gun (14) is designed to be no less than 1050℃; the secondary air pressure of the incinerator (1) should be maintained at no less than 600 Pa.

6. The energy-saving and efficient multi-stage synergistic acid removal system for a waste incinerator according to claim 5, characterized in that: The nozzles of several of the calcium carbonate spray guns (14) are either butterfly-shaped or multi-directional dispersion nozzles.

7. The energy-saving and efficient multi-stage synergistic acid removal system for a waste incinerator according to claim 2, characterized in that: The high-activity lime spraying device includes several lime spray guns (91) disposed on the evaporator (9). Several flue vents (92) are opened on the outside of the evaporator (9). The nozzles of several lime spray guns (91) are respectively inserted into several flue vents (92).

8. The energy-saving and efficient multi-stage synergistic acid removal system for a waste incinerator according to claim 7, characterized in that: The lime spray gun (91) is provided in several units, and the lime spray gun (91) is provided on the evaporator (9), and the nozzles of the lime spray gun (91) are all butterfly-shaped nozzles or multi-directional dispersion nozzles.

9. The energy-saving and efficient multi-stage synergistic acid removal system for a waste incinerator according to claim 2, characterized in that: It also includes a gas-water heat exchanger one (51) and a gas-water heat exchanger two (6). The gas-water heat exchanger one (51) is located at the connecting flue (5). A steam-air preheater (7) and a primary air fan (8) are also provided on one side of the incinerator (1). The output end of the steam-air preheater (7) is connected to the first flue (11). The gas-water heat exchanger two (6) is connected between the steam-air preheater (7) and the gas-water heat exchanger one (51). The input end of the gas-water heat exchanger two (6) is connected to the output end of the primary air fan (8).

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