A garbage incineration high-acidity pollutant flue gas purification system and purification process

Abstract

This invention discloses a flue gas purification system and process for high-acid pollutant flue gas from waste incineration, relating to the field of flue gas purification technology for waste incineration. The flue gas purification system includes the following components: a first-stage dry reactor for receiving high-temperature flue gas and performing first-stage deacidification treatment; a first-stage dust removal device; a high-temperature economizer; a second-stage dry reactor for receiving flue gas cooled by the high-temperature economizer and performing low-temperature deacidification treatment and removal of dioxins and heavy metals; a second-stage dust removal device; and a denitrification device for denitrifying the flue gas. The flue gas purification process in this application, when treating flue gas with high concentrations of acidic pollutants, can achieve efficient and synergistic removal of multiple pollutants, ultimately achieving multiple technical effects such as "achieving purification efficiency standards, improving energy utilization, reducing treatment costs, and optimizing power generation efficiency."

Description

Technical Field

[0001] This invention relates to the field of waste incineration flue gas purification technology, and in particular to a waste incineration high-acid pollutant flue gas purification system and purification process. Background Technology

[0002] With the widespread application of waste incineration technology in the waste disposal field, the treatment of flue gas pollutants generated during incineration has become a crucial aspect of environmental governance. Among these, the purification of flue gas with high concentrations of acidic pollutants is particularly challenging. This type of flue gas not only contains large amounts of acidic gases but also includes nitrogen oxides, high concentrations of dust, dioxins, heavy metals, and other toxic substances, posing a potential threat to the ecological environment and human health. Currently, environmental regulations are increasingly stringent on the emissions from waste incineration flue gas, requiring the concentrations of various pollutants to be controlled at extremely low levels. This presents greater challenges to the treatment efficiency, operational stability, and overall economic efficiency of flue gas purification systems.

[0003] To address the dual requirements of high acidic pollutant concentrations and ultra-low emissions, the industry currently widely adopts a complete flue gas treatment process: "rotary spray semi-dry acid removal + dry acid removal + activated carbon injection + bag filter + GGH (flue gas-to-flue gas heat exchanger) + wet acid removal + SGH (flue gas steam heater) + low-temperature SCR (selective catalytic reduction denitrification)". This process, through multi-unit series synergy, attempts to sequentially complete the preliminary removal of acidic gases, dioxin and heavy metal adsorption, dust collection, deep removal of acidic gases, and removal of nitrogen oxides to meet emission requirements.

[0004] However, the existing processes described above have several significant drawbacks when treating flue gas with high concentrations of acidic pollutants, making it difficult to simultaneously achieve both high-efficiency decontamination and economic energy conservation goals: First, to meet the reaction conditions of the rotary spray semi-dry desulfurization process, the exhaust gas temperature of the waste heat boiler needs to be maintained above 180℃, resulting in insufficient heat recovery and a significant reduction in thermal efficiency; Second, for high concentrations of acidic pollutants, relying solely on "rotary spray semi-dry desulfurization + dry desulfurization" is insufficient to achieve ultra-low emission requirements, necessitating the addition of a wet desulfurization unit. Wet desulfurization generates large amounts of desulfurization wastewater and dehumidification wastewater, which are complex in composition, difficult to treat, and significantly increase wastewater treatment costs; Third, the rotary spray semi-dry desulfurization process... Both the spray semi-dry and wet desulfurization processes require water to be sprayed into the flue gas, resulting in a significant drop in flue gas temperature and a waste of the large amount of heat energy carried by the flue gas, which cannot be effectively recovered and utilized. Fourth, the low-temperature SCR denitrification technology requires a minimum flue gas temperature of 180℃. Therefore, after wet desulfurization, the low-temperature flue gas needs to be heated by an SGH steam heater, which consumes a large amount of steam and directly reduces the overall power generation efficiency of the plant. Fifth, in the existing process, the adsorption of dioxins and heavy metals and the removal of acidic pollutants are carried out simultaneously. All fly ash collected by the bag filter becomes hazardous waste due to the adsorption of toxic and harmful substances, requiring complex stabilization treatment, which increases the amount of fly ash to be treated and drives up the treatment cost.

[0005] In summary, existing waste incineration flue gas treatment processes suffer from several key problems when dealing with high concentrations of acidic pollutants and ultra-low emission requirements. These problems include low waste heat utilization efficiency, high wastewater and fly ash treatment costs, high energy consumption, and reduced power generation efficiency. Consequently, they struggle to achieve the comprehensive goals of "high-efficiency decontamination, low-cost operation, and high energy recovery." Therefore, there is an urgent need for a novel flue gas purification process that can specifically address these shortcomings, ensuring efficient purification of flue gas with high acidic pollutant concentrations while simultaneously improving energy utilization efficiency and reducing treatment costs. Summary of the Invention

[0006] This invention discloses a purification system and process for flue gas containing highly acidic pollutants from waste incineration, in order to solve the aforementioned technical problems in related technologies.

[0007] To solve the above problems, the present invention adopts the following technical solution:

[0008] In a first aspect, this application provides a flue gas purification system for highly acidic pollutants from waste incineration, comprising the following components connected sequentially along the flue gas flow direction:

[0009] The first-stage dry reactor has a first flue gas inlet pipe and a first deacidifying agent injection assembly is provided on the first flue gas inlet pipe. The first deacidifying agent is injected into the flue gas through the first deacidifying agent injection assembly. The first-stage dry reactor is used to receive high-temperature flue gas and perform first-stage deacidification treatment.

[0010] The first-stage dust removal device is used to remove dust from the flue gas after the first-stage deacidification treatment;

[0011] High-temperature economizers are used to cool flue gas and recover waste heat.

[0012] The second-stage dry reactor has a first flue gas inlet pipe, and a second deacidifying agent injection assembly and an activated carbon injection assembly are installed on the second flue gas inlet pipe. The second deacidifying agent is injected into the flue gas through the second deacidifying agent injection assembly, and activated carbon is injected into the flue gas through the activated carbon injection assembly. The second-stage dry reactor is used to receive the flue gas cooled by the high-temperature economizer and perform low-temperature deacidification treatment and removal of dioxins and heavy metals.

[0013] The second-stage dust removal device is used for final dust removal of the flue gas after the second-stage deacidification treatment;

[0014] Among them, a first fly ash recycling component is provided between the first-stage dry reactor and the first-stage dust removal device for recycling the first fly ash collected by the first-stage dust removal device back to the first-stage deacidification treatment.

[0015] Between the second-stage dry reactor and the second-stage dust removal device, there is also a second fly ash recycling component for recycling the second fly ash collected by the second-stage dust removal device back to the second-stage deacidification treatment, and a fly ash humidification component for humidifying the second fly ash.

[0016] It also includes a denitrification device for treating flue gas, wherein the denitrification device is configured in one of the following two ways:

[0017] Method 1: The denitrification device is connected in series between the first-stage dust removal device and the high-temperature economizer along the flue gas flow direction;

[0018] Method 2: The denitrification device is connected in series downstream of the second-stage dust removal device along the flue gas flow direction.

[0019] Secondly, this application provides a process for purifying flue gas containing high-acid pollutants from waste incineration. The process utilizes the aforementioned flue gas purification system for high-acid pollutants from waste incineration to purify the flue gas, including:

[0020] High-temperature flue gas is introduced into the first-stage dry reactor, and the first deacidifying agent is injected into the flue gas to carry out the first-stage deacidification treatment. The reaction temperature of the first-stage deacidification treatment is 300-350℃.

[0021] The flue gas after the first stage of deacidification treatment is subjected to the first stage of dust removal device for the first stage of dust removal treatment; the first fly ash from the first stage of dust removal treatment is collected and recycled back to the first stage of deacidification treatment;

[0022] The flue gas is introduced into a denitrification unit for denitrification treatment;

[0023] A high-temperature economizer is used to cool the flue gas and recover waste heat, reducing the flue gas temperature to 145-200℃;

[0024] The cooled flue gas is introduced into the second-stage dry reactor, where a second deacidifying agent and activated carbon are injected into the flue gas for second-stage deacidification treatment and removal of dioxins and heavy metals.

[0025] The flue gas after the second-stage deacidification treatment is subjected to a second-stage dust removal device for second-stage dust removal treatment; the second fly ash from the second-stage dust removal treatment is collected, and the second fly ash is humidified and recycled back to the second-stage deacidification treatment.

[0026] The denitrification treatment is performed after the first-stage dust removal; or, the denitrification treatment is performed after the second-stage dust removal.

[0027] The technical solution adopted in this invention can achieve the following beneficial effects:

[0028] The waste incineration high-acid pollutant flue gas purification system proposed in this application, through its core architecture design of "two-stage high-efficiency fly ash circulation dry gradient deacidification + segmented dust removal + waste heat recovery + flexible denitrification," can specifically address the prominent drawbacks of existing processes in treating high-acid pollutant flue gas. When applying the waste incineration high-acid pollutant flue gas purification system of this application to treat high-acid pollutant concentration flue gas, it not only overcomes the bottlenecks of existing processes such as "wasteful waste heat, large amounts of wastewater, high energy consumption, and large amounts of hazardous waste," but also achieves efficient synergistic removal of multiple pollutants, ultimately achieving multiple technical effects such as "achieving purification efficiency standards, improving energy utilization, reducing treatment costs, and optimizing power generation efficiency," as detailed below:

[0029] (1) The waste incineration high acid pollutant flue gas purification system proposed in this application improves the waste heat utilization efficiency of flue gas and solves the problems of low thermal efficiency of waste heat boiler and waste of flue gas heat energy. First, the first-stage dry reactor is adapted to high-temperature flue gas. In the high-temperature section, SO2 is finally converted into calcium sulfate by the injection of the first deacidifying agent (slaked lime), and then removed by the first-stage dust removal device. Since most of the SO2 is removed in advance in the high-temperature section, the raw materials for sulfuric acid generation in the subsequent low-temperature section (waste heat utilization stage) are greatly reduced, and the amount of sulfuric acid condensation is significantly reduced. Thus, the low-temperature corrosion after the waste heat utilization of flue gas is greatly alleviated by the pre-removal of SO2, breaking the limitation of "waste heat boiler needs to exhaust flue gas at a high level", so that the waste heat boiler can reduce the exhaust temperature according to the heat recovery needs, fully extract the heat energy in the flue gas, and directly improve the thermal efficiency of the waste heat boiler. Second, the added high-temperature economizer can enhance the waste heat recovery. First, after the first-stage dust removal, the flue gas is cooled, and the waste heat recovered during the cooling process is converted into usable energy, such as heating the working fluid, instead of the meaningless loss of heat energy due to water spraying temperature drop as in existing processes. This further maximizes the recovery and utilization rate of flue gas heat energy. Second, the entire purification system is designed without water spraying during the flue gas purification process. Both stages of acid removal adopt a dry process of fly ash circulation, which does not require water spraying into the flue gas. At the same time, it can ensure high acid removal efficiency, avoid the large temperature drop of flue gas caused by water spraying from the source, and ensure that the flue gas heat energy is always within a reasonable range of recovery and utilization. At the same time, it can adapt to the temperature required for both stages of acid removal and denitrification, ensuring the efficiency of acid removal and denitrification.

[0030] (2) The waste incineration high-acid pollutant flue gas purification system proposed in this application adopts a two-stage fly ash circulation dry deacidification method, eliminating the need for wet deacidification and solving the problem of high wastewater treatment costs. First, the first-stage dry reactor undertakes "high-temperature coarse deacidification," receiving high-temperature flue gas from the waste heat boiler outlet. After injecting the first deacidification agent, the high reactivity of the deacidification agent under high-temperature conditions can be utilized. Through sufficient residence time in the first-stage dry reactor and multiple reactions in the first fly ash circulation, most of the acidic gases in the high-acid pollutant flue gas can be quickly removed, reducing the load for subsequent deep deacidification. Second, the second-stage fly ash circulation dry reactor undertakes "low-temperature fine deacidification." In the flue gas environment cooled by the high-temperature economizer, the second deacidification agent is injected to specifically and deeply remove residual acidic gases. This invention utilizes a two-stage dry process to simultaneously spray activated carbon to adsorb dioxins and heavy metals. This creates a gradient deacidification system with high-temperature peak shaving and low-temperature residue collection, achieving ultra-low emission requirements for the removal of high-concentration acidic gases. Unlike existing processes, it eliminates the need for a wet deacidification unit, completely eliminating the generation of deacidification and dehumidification wastewater, significantly reducing wastewater treatment costs and difficulty. Furthermore, to prevent scaling and corrosion in the wastewater treatment system, auxiliary agents such as corrosion inhibitors and scale inhibitors need to be added to the wet system. The procurement and operating costs of these auxiliary agents are essentially hidden costs of the deacidification process. This application eliminates the need for a wet deacidification unit, eliminating the generation of deacidification and dehumidification wastewater at the source. This not only saves direct wastewater treatment costs but also avoids the continuous consumption of auxiliary agents in the wet system.

[0031] (3) The waste incineration high-acid pollutant flue gas purification system proposed in this application adopts a two-stage fly ash recycling dry desulfurization process, which realizes the efficient reuse and on-demand application of desulfurization agents, reduces the amount of desulfurization agents added and the cost of use, and simultaneously reduces the fly ash production and disposal costs. In the first-stage dry desulfurization stage, after the first desulfurization agent injected by the first desulfurization agent injection component reacts with the flue gas, the residual first desulfurization agent that has not fully participated in the reaction is collected by the first-stage dust removal device along with the first fly ash. The first fly ash recycling component recycles these first fly ashes for the first-stage desulfurization treatment, allowing the residual first desulfurization agent to react with the flue gas again. This process not only avoids the waste of unreacted agents directly discharged with fly ash in the traditional process and reduces the amount of fresh first desulfurization agent to be replenished, but also reduces the amount of fly ash emitted per emission due to the recycling of fly ash - the fly ash that originally needed to be directly discharged is partially recycled to participate in the reaction without increasing the discharge volume, thus controlling the scale of fly ash generation from the source. After entering the second-stage deacidification process, the fly ash humidification component first humidifies the second-stage fly ash collected by the second-stage dust removal device to enhance its reactivity. Then, it is recycled back to the second-stage deacidification process via the second-stage fly ash recycling component, allowing the residual components of the second deacidifying agent to be reused. Simultaneously, since the first stage has already removed most of the acidic gases, the second deacidifying agent injection component only needs to be supplemented with a small amount of reagent to treat residual pollutants. The addition of a small amount of reagent itself reduces the amount of reaction products generated, and combined with the recycling of fly ash, further reduces the total amount of fly ash ultimately discharged. The reduction in fly ash production directly leads to a decrease in disposal costs: on the one hand, it reduces the containers and transportation capacity required for fly ash transportation and storage, lowering the costs of intermediate stages; on the other hand, because the amount of fly ash requiring final harmless treatment (such as solidification and stabilization, landfill, etc.) is reduced, the corresponding consumption of treatment reagents, equipment operating costs, and landfill site occupancy costs are significantly reduced, achieving a double saving in deacidifying agent costs and fly ash disposal costs.

[0032] (4) The waste incineration high acid pollutant flue gas purification system proposed in this application has a treatment route designed specifically according to the temperature of the flue gas during the flue gas treatment process. During the flue gas purification process, there is no need to heat the flue gas again, which solves the problems of steam consumption of SGH and low power generation efficiency of the whole plant. First, the dry process described in this application avoids the deep low temperature of flue gas caused by wet desulfurization, such as the 50-60℃ drop of flue gas after wet desulfurization in existing processes. This ensures that the flue gas temperature is always maintained within a reasonable range suitable for the denitrification reaction. Second, if the denitrification device is located "between the first-stage dust removal device and the high-temperature economizer," the flue gas still retains the high-temperature characteristics of the waste heat boiler outlet, which can directly meet the temperature requirements of the denitrification reaction. If it is located "downstream of the second-stage dust removal device," since there is no wet cooling, the flue gas temperature is still at a level suitable for denitrification without additional heating. Unlike existing processes, it does not rely on SGH to consume steam for heating, reducing steam consumption and directly improving the overall plant power generation efficiency. Compared with the existing conventional water-spraying semi-dry desulfurization process, the power generation efficiency can be increased by 2.7%-3.5%.

[0033] (5) The waste incineration high acid pollutant flue gas purification system proposed in this application adopts a two-stage dust removal treatment to classify and treat fly ash, thus solving the problem that all fly ash is hazardous waste and the treatment cost is high. First, the first-stage dust removal pre-treatment (before activated carbon injection): The first-stage dust removal device is used to treat the flue gas after the first-stage deacidification. At this time, activated carbon has not yet been injected. The first fly ash collected is only the first-stage deacidification product and raw dust, which does not contain dioxins, heavy metals and other toxic and harmful substances. Depending on the requirements of different regions, simplified and compliant treatment can be selected, such as being classified as slag treatment; Second, the second-stage dust removal post-treatment (after activated carbon injection): Only the second fly ash collected by the second-stage dust removal device contains activated carbon that adsorbs dioxins and heavy metals, which is hazardous waste and needs to be stabilized; Thus, this application separates hazardous waste fly ash from non-hazardous waste fly ash through two-stage fly ash treatment, which greatly reduces the total amount of hazardous waste fly ash and reduces the workload and cost of fly ash stabilization treatment.

[0034] (6) The waste incineration high acid pollutant flue gas purification system proposed in this application can adapt to high acid pollutant flue gas through "two-stage fly ash circulation dry gradient deacidification + segmented dust removal + waste heat recovery + flexible denitrification", ensuring that the high acid pollutant flue gas purification meets the standards and taking into account the synergistic removal of multiple pollutants. First, for high-concentration acidic gases, a two-stage circulating dry deacidification process is adopted. The synergistic effect of high-temperature coarse deacidification and low-temperature fine deacidification ensures efficient removal of acidic gases and meets ultra-low emission requirements. Second, activated carbon injection is synchronized with the second-stage deacidification. Low-temperature second-stage deacidification and dioxin / heavy metal adsorption are simultaneously completed in the second-stage dry reactor, enabling synergistic treatment of multiple pollutants. Third, a two-stage dust removal system with flexible denitrification is employed. The first-stage dust removal removes most of the dust to ensure subsequent waste heat recovery and deacidification efficiency, while the second-stage dust removal achieves final dust removal to ensure dust compliance. The denitrification unit's flexible layout ensures effective removal of nitrogen oxides. Therefore, the waste incineration high-acidic pollutant flue gas purification system in this application can comprehensively remove acidic gases, dioxins / heavy metals, dust, and nitrogen oxides from high-acidic pollutant flue gas, ensuring that the final emission of high-acidic pollutant flue gas meets stringent standards. Attached Figure Description

[0035] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0036] Figure 1 This is a schematic diagram of the structure of the first embodiment of this application;

[0037] Figure 2 This is a schematic diagram of the structure of the second embodiment of the present application;

[0038] Figure 3 This is a structural schematic diagram of the third embodiment of the present application;

[0039] Figure 4 This is a structural schematic diagram of the fourth embodiment of this application;

[0040] Figure 5 This is a structural schematic diagram of the fifth embodiment of this application;

[0041] Figure 6 This is a structural schematic diagram of the sixth embodiment of the present application.

[0042] In the diagram: 1. First-stage dry reactor; 2. First-stage dust removal device; 3. Denitrification device; 4. High-temperature economizer; 5. Second-stage dry reactor; 6. Second-stage dust removal device; 7. First fly ash circulation assembly; 701. First fly ash discharge pipe; 702. First fly ash collection pipe; 703. First fly ash circulation fluidized bed; 704. First fly ash conveying pipe; 8. Second fly ash circulation assembly; 801. Second fly ash discharge pipe; 802. Second fly ash collection pipe; 803. Second fly ash circulation fluidized bed; 80 4. Second fly ash conveying pipeline; 9. Fly ash humidification assembly; 10. First integrated dust removal and denitrification device; 11. Waste heat boiler; 12. Deaerator feedwater pipeline; 13. High-temperature economizer outlet pipeline; 14. Low-temperature economizer outlet pipeline; 15. Second integrated dust removal and denitrification device; 16. Activated carbon injection assembly; 17. Second deacidifying agent injection assembly; 18. First flue gas inlet pipeline; 19. Second flue gas inlet pipeline; 20. First deacidifying agent injection assembly; 21. Low-temperature economizer; 22. Deaerator; 23. Condensate pipeline. Detailed Implementation

[0043] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be described in detail below. Obviously, the described embodiments are merely some embodiments of this invention, and not all embodiments. Based on the embodiments of this invention, all other implementation methods obtained by those skilled in the art without creative effort are within the scope of protection of this invention.

[0044] The terms "first," "second," etc., used in the specification and claims of this application are used to distinguish similar objects and not to describe a specific order or sequence. It should be understood that such use of data can be interchanged where appropriate so that embodiments of this application can be implemented in orders other than those illustrated or described herein, and the objects distinguished by "first," "second," etc., are generally of the same class and the number of objects is not limited; for example, a first object can be one or more. Furthermore, in the specification and claims, "and / or" indicates at least one of the connected objects, and the character " / " generally indicates that the preceding and following objects are in an "or" relationship.

[0045] The following is in conjunction with the appendix Figures 1 to 6 This application provides a detailed description of a waste incineration high-acid pollutant flue gas purification system and a waste incineration high-acid pollutant flue gas purification process through specific embodiments and application scenarios.

[0046] Example 1:

[0047] This application provides a flue gas purification system for high-acid pollutants from waste incineration, comprising the following components connected sequentially along the flue gas flow direction:

[0048] The first-stage dry reactor 1 has its flue gas inlet connected to the flue gas outlet of the waste heat boiler 11 via a first flue gas inlet pipe 18 (or, the flue gas inlet of the first-stage dry reactor 1 is connected to the flue gas outlet of the superheater via the first flue gas inlet pipe 18). A first deacidifying agent injection assembly 20 is provided on the first flue gas inlet pipe 18 of the first-stage dry reactor 1. A first deacidifying agent is injected into the flue gas through the first deacidifying agent injection assembly 20. The first-stage dry reactor 1 is used to receive the high-temperature flue gas from the outlet of the waste heat boiler 11 and perform first-stage deacidification treatment on the flue gas.

[0049] The first-stage dust removal device 2 has its flue gas inlet connected to the flue gas outlet of the first-stage dry reactor 1 via a flue, and is used to remove dust from the flue gas after the first-stage deacidification treatment.

[0050] The high-temperature economizer 4 has its flue gas inlet connected to the flue gas outlet of the first-stage dust removal device 2 or the flue gas outlet of the denitrification device 3 via a flue. The high-temperature economizer 4 is equipped with a working fluid circulation component for cooling the incoming flue gas and recovering the waste heat of the flue gas through the working fluid circulation component.

[0051] The second-stage dry reactor 5 has its flue gas inlet connected to the flue gas outlet of the high-temperature economizer 4 via a second flue gas inlet pipe 19. The second flue gas inlet pipe 19 of the second-stage dry reactor 5 is equipped with a second deacidifying agent injection assembly 17 and an activated carbon injection assembly 16. The second deacidifying agent is injected through the second deacidifying agent injection assembly 17, and activated carbon is injected through the activated carbon injection assembly 16. The second-stage dry reactor 5 is used to receive the flue gas cooled by the high-temperature economizer 4 and to perform low-temperature deacidification treatment and removal of dioxins and heavy metals from the flue gas.

[0052] The second-stage dust removal device 6 is used to perform final dust removal on the flue gas after the second-stage deacidification treatment; the flue gas inlet of the second-stage dust removal device 6 is connected to the flue gas outlet of the second-stage dry reactor 5 through a flue, and is used to perform final dust removal on the flue gas after the second-stage deacidification treatment, and the flue gas outlet of the second-stage dust removal device 6 is used to connect to the subsequent flue gas discharge or the flue gas inlet of the denitrification device 3 described below.

[0053] Among them, a first fly ash recycling component 7 is provided between the first-stage dry reactor 1 and the first-stage dust removal device 2 for recycling the first fly ash collected by the first-stage dust removal device 2 back to the first-stage deacidification treatment; the first fly ash recycling component 7 is used to transport the first fly ash collected by the first-stage dust removal device 2 and recycle it back to the first-stage dry reactor 1 to participate in the first-stage deacidification treatment.

[0054] Between the second-stage dry reactor 5 and the second-stage dust removal device 6, there is also a second fly ash circulation component 8 for recycling the second fly ash collected by the second-stage dust removal device 6 back to the second-stage deacidification treatment and a fly ash humidification component 9 for humidifying the second fly ash; the second fly ash circulation component 8 is used to transport and circulate the second fly ash collected by the second-stage dust removal device 6 back to the second-stage dry reactor 5 to participate in the second-stage deacidification treatment;

[0055] It also includes a denitrification device 3 for denitrification treatment of flue gas, wherein the denitrification device 3 is configured in one of the following two ways:

[0056] Method 1: For example Figure 1 , Figure 3 and Figure 5 As shown, the denitrification device 3 is connected in series between the first-stage dust removal device 2 and the high-temperature economizer 4 along the flue gas flow direction, and the flue gas inlet of the denitrification device 3 is connected to the flue gas outlet of the first-stage dust removal device 2 through a flue, and the flue gas outlet of the denitrification device 3 is connected to the flue gas inlet of the high-temperature economizer 4 through a flue.

[0057] Method 2: For example Figure 2 , Figure 4 and Figure 6 As shown, the denitrification device 3 is connected in series downstream of the second-stage dust removal device 6 along the flue gas flow direction, and the flue gas inlet of the denitrification device 3 is connected to the flue gas outlet of the second-stage dust removal device 6 through a flue.

[0058] In some embodiments, when the denitrification device 3 is located downstream of the second-stage dust removal device 6, a low-temperature economizer 21 connected in series downstream of the denitrification device 3 is also included to cool the flue gas and recover waste heat. It is understood that since the denitrification device 3 is located downstream of the second-stage dust removal device 6, the flue gas after denitrification still carries a certain amount of usable heat energy. The low-temperature economizer 21 can cool it down and simultaneously convert the recovered waste heat into usable energy, such as preheating condensate or heating the working fluid, avoiding the meaningless waste of this end-stage heat energy and further improving the overall system's waste heat utilization efficiency. At the same time, the cooled flue gas is more suitable for subsequent emission requirements, such as reducing the exhaust temperature to a more reasonable range, without the need for additional energy consumption to regulate the temperature, thus balancing energy recovery and system emission stability.

[0059] In some embodiments, the denitrification device 3 is positioned between the first-stage dust removal device 2 and the high-temperature economizer 4:

[0060] The first stage of dust removal uses an electrostatic precipitator, metal filter bag, or ceramic filter cartridge, and then the flue gas after the first stage of dust removal is treated with high-temperature SCR denitrification; or, the first stage of dust removal and denitrification treatment are combined with a first integrated dust removal and denitrification device 10 that integrates the dust collector (ceramic catalytic filter cartridge or metal catalytic filter bag) and the denitrification device.

[0061] The second-stage dust removal uses a bag filter. It is understandable that the first-stage dust removal device 2 can use an electrostatic precipitator, metal filter bags, or ceramic filter cartridges, all of which are suitable for high-temperature flue gas; alternatively, it can use an integrated dust removal and denitrification device 10 with ceramic catalytic filter cartridges / metal catalytic filter bags. The former can efficiently remove most of the dust in a high-temperature environment, avoiding dust affecting the subsequent high-temperature SCR denitrification efficiency, and unlike existing processes, it does not rely on SGH heating, directly utilizing high-temperature flue gas to meet the denitrification temperature requirements, reducing steam consumption; the latter integrates dust removal and denitrification, saving the installation space and energy consumption of separate denitrification equipment and simplifying the system process.

[0062] In some embodiments, the denitrification device 3 is located downstream of the second-stage dust removal device 6:

[0063] The first stage of dust removal uses electrostatic precipitators, metal filter bags, or ceramic filter cartridges;

[0064] The second-stage dust removal uses a bag filter, followed by low-temperature SCR denitrification; alternatively, the second-stage dust removal and denitrification processes can be handled by a second integrated dust removal and denitrification device 15, which combines a dust collector (using catalytic filter bags or ceramic filter cartridges) with a denitrification unit. It is understood that when the denitrification unit 3 is located downstream of the second-stage dust removal unit 6, the second-stage dust removal can use either a bag filter or the second integrated dust removal and denitrification device 15 with ceramic catalytic filter cartridges / bags. The former ensures final dust removal meets dust standards, and subsequent low-temperature SCR requires no additional heating. Because there is no wet cooling, the flue gas temperature is suitable for low-temperature denitrification, avoiding the steam consumption drawback of SGH. The latter, also through integrated design, simultaneously completes final dust removal and denitrification, reducing equipment redundancy, lowering system operation and maintenance costs, and further optimizing the balance between high-efficiency decontamination and low energy consumption. It should be noted that if this method is used, the temperature control in the second-stage dry acid removal process should be between 180-195℃, and the desulfurization agent should be sodium bicarbonate or high-ratio slaked lime.

[0065] In some embodiments, the first fly ash circulation assembly 7 includes a first fly ash collection pipe 702, a first fly ash circulation fluidized bed 703 located at the end of the first fly ash collection pipe 702, and a first fly ash conveying pipe 704 connected to the first fly ash circulation fluidized bed 703. The other end of the first fly ash conveying pipe 704 is connected to the first-stage dry reactor 1. The first fly ash collection pipe 702 is used to collect the first fly ash captured by the first-stage dust removal device 2 and convey the first fly ash to the first fly ash circulation fluidized bed 703. The first fly ash conveying pipe 704 is used to convey the first fly ash in the first fly ash circulation fluidized bed 703 to the first-stage dry reactor 1 to participate in the first-stage deacidification treatment. A first fly ash discharge pipe 701 is provided at the bottom of the first fly ash circulation fluidized bed 703. When the first fly ash in the first fly ash circulation fluidized bed 703 reaches a certain level, ash is discharged in an intermittent manner. Understandably, the first fly ash is a product collected by the first-stage dust removal device 2. Since activated carbon has not yet been sprayed at this stage, the first fly ash contains the first-stage deacidification products and raw dust, and the temperature is relatively high. Heavy metals and activated carbon are not easily adsorbed in the first fly ash. Therefore, depending on local requirements, it may be classified as non-hazardous waste. Furthermore, since the first fly ash contains unreacted first deacidification agent, recycling the first fly ash through the first fly ash recycling component 7 for use in the first-stage dry deacidification allows the unreacted first deacidification agent in the first fly ash to participate again in the removal of high-concentration acidic gases, reducing the amount of fresh first deacidification agent added and lowering deacidification costs. At the same time, the recycling of the first fly ash reduces the amount of non-hazardous waste fly ash discharged, significantly alleviating the pressure and cost of fly ash treatment.

[0066] In some embodiments, the second fly ash circulation assembly 8 includes a second fly ash collection pipe 802, a second fly ash circulation fluidized bed 803 located at the end of the second fly ash collection pipe 802, and a second fly ash conveying pipe 804 connected to the second fly ash circulation fluidized bed 803. The other two ends of the second fly ash conveying pipe 804 are connected to the second-stage dry reactor 5. The second fly ash collection pipe 802 is used to collect the second fly ash captured by the second-stage dust removal device 6 and convey the second fly ash to the second fly ash circulation fluidized bed 803. The second fly ash conveying pipe 804 is used to convey the second fly ash in the second fly ash circulation fluidized bed 803 to the second-stage dry reactor 5 to participate in the second-stage deacidification treatment. A second fly ash discharge pipe 801 is provided at the bottom of the second fly ash circulation fluidized bed 803. When the second fly ash in the second fly ash circulation fluidized bed 803 reaches a certain level, ash is discharged in an intermittent manner. The fly ash humidification component 9 is connected to the second fly ash conveying pipeline 804 of the second fly ash circulation component 8, and is used to humidify the second fly ash to be recycled back to the second-stage dry reactor 5. It is understood that the second fly ash circulation component 8 reuses the second fly ash (containing unreacted second deacidifying agent) collected by the second-stage dust removal device 6 for the second-stage dry deacidification, which can fully utilize the remaining deacidification capacity in the second fly ash, making the usage of the second deacidifying agent more reasonable, avoiding excessive input, and reducing deacidification costs. The fly ash humidification component 9 humidifies the circulating second fly ash, and a water film forms on the surface of the second fly ash after humidification, which can promote the reaction between the second deacidifying agent and residual acidic gases, further enhancing the deep deacidification efficiency and ensuring that highly acidic pollutants meet standards. At the same time, the circulation of the second fly ash reduces the total amount of hazardous waste fly ash discharged. Even the recycled fly ash, due to the full utilization of deacidification capacity, reduces the cost per unit of treatment, balancing deacidification efficiency and hazardous waste reduction requirements.

[0067] In some embodiments, the flue gas purification system further includes an induced draft fan for discharging the purified flue gas; when the denitrification device 3 is located between the first-stage dust removal device 2 and the high-temperature economizer 4, the induced draft fan is located downstream of the second-stage dust removal device 6; when the denitrification device 3 is located downstream of the second-stage dust removal device 6, the induced draft fan is located downstream of the low-temperature economizer 21.

[0068] like Figure 1As shown, the flue gas inlet of the first-stage dry reactor 1 is connected to the flue gas outlet of the superheater via the first flue gas inlet pipe 18. The superheater is not shown in the figure. The denitrification device 3 is connected in series between the first-stage dust removal device 2 and the high-temperature economizer 4 along the flue gas flow direction. The flue gas inlet of the denitrification device 3 is connected to the flue gas outlet of the first-stage dust removal device 2 via a flue, and the flue gas outlet of the denitrification device 3 is connected to the flue gas inlet of the high-temperature economizer 4 via a flue, so as to perform denitrification treatment on the flue gas after the first-stage dust removal. Furthermore, the first-stage dust removal device 2 and the denitrification device 3 adopt an integrated first integrated dust removal and denitrification device 10 for dust removal and denitrification treatment; of course, the first-stage dust removal device 2 and the denitrification device 3 can also be separate devices.

[0069] like Figure 2 As shown, the flue gas inlet of the first-stage dry reactor 1 is connected to the flue gas outlet of the superheater via the first flue gas inlet pipe 18 (the superheater is not shown in the figure). The denitrification device 3 is connected in series downstream of the second-stage dust removal device 6 along the flue gas flow direction, and the flue gas inlet of the denitrification device 3 is connected to the flue gas outlet of the second-stage dust removal device 6 via a flue to perform denitrification treatment on the clean flue gas after final dust removal. The flue gas outlet of the denitrification device 3 is connected to the flue gas inlet of the low-temperature economizer 21 via a flue. Furthermore, the second-stage dust removal device 6 and the denitrification device 3 adopt an integrated second integrated dust removal and denitrification device 15 for dust removal and denitrification treatment; of course, the second-stage dust removal device 6 and the denitrification device 3 can also be separate devices.

[0070] like Figure 3 and Figure 5As shown, the flue gas inlet of the first-stage dry reactor 1 is connected to the flue gas outlet of the waste heat boiler 11 through the first flue gas inlet pipe 18, for receiving the high-temperature flue gas discharged from the waste heat boiler 11; the denitrification device 3 is connected in series between the first-stage dust removal device 2 and the high-temperature economizer 4 along the flue gas flow direction, and the flue gas inlet of the denitrification device 3 is connected to the flue gas outlet of the first-stage dust removal device 2 through a flue, and the flue gas outlet of the denitrification device 3 is connected to the flue gas inlet of the high-temperature economizer 4 through a flue, so as to perform denitrification treatment on the flue gas after the first-stage dust removal. Deoxygenated feedwater is transported to the feedwater inlet of the high-temperature economizer 4 via deoxygenated feedwater pipeline 12. After heat exchange with the denitrified flue gas in the high-temperature economizer 4 (simultaneously recovering waste heat from the flue gas), the feedwater is then transported to the feedwater inlet of the waste heat boiler 11 via the high-temperature economizer outlet pipeline 13. After entering the waste heat boiler 11, the deoxygenated feedwater continues to absorb the high-temperature heat generated by waste incineration, ultimately generating saturated steam or superheated steam. This steam can be used to: drive the turbine to rotate and generate electricity, realizing the resource utilization of waste incineration heat energy; or provide a power source for auxiliary equipment (such as induced draft fans and forced draft fans) within the waste incineration plant; or serve as steam for plant production (such as fly ash stabilization treatment and wastewater heating) or domestic use (such as heating), improving the overall energy utilization rate. Figure 3 The first-stage dust removal device 2 and the denitrification device 3 adopt an integrated first-stage dust removal and denitrification device 10; Figure 5 The first-stage dust removal device 2 and the denitrification device 3 are separate units.

[0071] like Figure 4 and Figure 6As shown, the flue gas inlet of the first-stage dry reactor 1 is connected to the flue gas outlet of the waste heat boiler 11 through the first flue gas inlet pipe 18, and is used to receive the high-temperature flue gas discharged from the waste heat boiler 11; the denitrification device 3 is connected in series downstream of the second-stage dust removal device 6 along the flue gas flow direction, and the flue gas inlet of the denitrification device 3 is connected to the flue gas outlet of the second-stage dust removal device 6 through the flue, and the flue gas outlet of the denitrification device 3 is connected to the flue gas inlet of the low-temperature economizer 21 through the flue, so as to perform denitrification treatment on the clean flue gas after final dust removal. Condensate is first transported to the feedwater inlet of the low-temperature economizer 21 via condensate pipeline 23. In the low-temperature economizer 21, it exchanges heat with the denitrified flue gas to recover waste heat from the end flue gas. Then, it is transported to the condensate inlet of the deaerator 22 via the low-temperature economizer outlet pipeline 14. After deoxygenation in the deaerator 22, the deaerated feedwater enters the high-temperature economizer 4 via the deaerated feedwater pipeline 12. In the high-temperature economizer 4, it exchanges heat with the upstream flue gas (such as the flue gas after the first-stage dust removal device 2 / before the second-stage dry reactor 5) to increase its temperature before exiting as high-temperature economizer effluent. Pipeline 13 delivers water to the feedwater inlet of the waste heat boiler 11. After entering the waste heat boiler 11, the deaerated feedwater absorbs the high-temperature heat from waste incineration to generate saturated steam or superheated steam. This steam can also be used to: drive the turbine to rotate and generate electricity, realizing the resource utilization of waste incineration heat energy; or provide a power source for auxiliary equipment (such as induced draft fans and forced draft fans) in the waste incineration plant; or, serve as steam for production in the plant (such as fly ash stabilization treatment and wastewater heating) or for domestic use (such as heating), improving the overall energy utilization rate. Figure 4 The second-stage dust removal device 6 and the denitrification device 3 adopt an integrated second-integrated dust removal and denitrification device 15; Figure 6 The second-stage dust removal device 6 and the denitrification device 3 are separate units.

[0072] Example 2:

[0073] This application provides a process for purifying flue gas containing high-acid pollutants from waste incineration. The process utilizes the waste incineration high-acid pollutant flue gas purification system described in Example 1 above, including:

[0074] High-temperature flue gas is introduced into the first-stage dry reactor 1, and the first deacidifying agent is injected into the flue gas to carry out the first-stage deacidification treatment. The reaction temperature of the first-stage deacidification treatment is 300-350℃.

[0075] The flue gas after the first stage of acid removal treatment is subjected to the first stage of dust removal device 2 for the first stage of dust removal treatment; the first fly ash from the first stage of dust removal treatment is collected and recycled back to the first stage of acid removal treatment.

[0076] The flue gas is introduced into the denitrification unit 3 for denitrification treatment;

[0077] The high-temperature economizer 4 is used to cool the flue gas and recover waste heat, reducing the flue gas temperature to 145-200℃;

[0078] The cooled flue gas is introduced into the second-stage dry reactor 5, and a second deacidifying agent and activated carbon are injected into the flue gas to carry out the second-stage deacidification treatment and remove dioxins and heavy metals.

[0079] The flue gas after the second-stage deacidification treatment is subjected to a second-stage dust removal device 6 for a second-stage dust removal treatment; the second fly ash from the second-stage dust removal treatment is collected, and the second fly ash is humidified and recycled back to the second-stage deacidification treatment.

[0080] The denitrification treatment is performed after the first-stage dust removal; or, the denitrification treatment is performed after the second-stage dust removal.

[0081] In some embodiments, when the denitrification treatment is carried out after the second-stage dust removal, the process also includes using a low-temperature economizer 21 to cool the flue gas and recover waste heat before the flue gas is discharged, thereby reducing the flue gas temperature to below 130°C.

[0082] In some embodiments, when the denitrification treatment is carried out after the second-stage dust removal, a high-temperature economizer 4 is used to reduce the flue gas temperature to 180-195°C. The second desulfurization agent includes sodium bicarbonate or a specific surface area greater than 40 m². 2 / g of high-ratio slaked lime; when sodium bicarbonate is used as the second deacidifying agent for the second-stage deacidification treatment, the excess coefficient of the second deacidifying agent is 1.05-1.2; when high-ratio slaked lime is used as the second deacidifying agent for the second-stage deacidification treatment, the excess coefficient of the second deacidifying agent is 1.2-1.8.

[0083] In some implementations, when the denitrification treatment is carried out after the second-stage dust removal, the inlet flue gas temperature of the second-stage dry reactor 5 is 180-195℃, the flue gas flow rate of the reactor is 10-13m / s, and the flue gas residence time is 0.8-1.2s.

[0084] In some implementations, when the denitrification treatment is carried out after the first-stage dust removal, a high-temperature economizer 4 is used to reduce the temperature of the flue gas to 155-165°C. The second deacidifying agent includes slaked lime. When slaked lime is used as the second deacidifying agent for the second-stage deacidification treatment, the excess coefficient of the second deacidifying agent is 1.2-1.5.

[0085] In some implementations, when the denitrification treatment is carried out after the first-stage dust removal, the inlet flue gas temperature of the second-stage dry reactor 5 is 155-165℃, and the outlet flue gas temperature is not higher than 150℃; the flue gas velocity in the reactor is 10-13m / s, and the flue gas residence time is 0.8-1.2s.

[0086] In some implementations, the first fly ash from the first stage of dust removal is collected and recycled for the first stage of acid removal; the recycling rate of the first fly ash is 20-70 times.

[0087] In some embodiments, the second fly ash from the second-stage dust removal treatment is collected and recycled for the second-stage deacidification, with a recycling ratio of 20-70 times; when slaked lime is used as the second deacidification agent, the second fly ash is humidified, with a humidification range of 1%-5%.

[0088] In some embodiments, during the first-stage deacidification treatment, the inlet flue gas temperature of the first-stage dry reactor 1 is 300-350℃, the reactor flow rate is 8-12m / s, and the residence time is 1.0-1.5s.

[0089] In some embodiments, the first deacidifying agent includes slaked lime, and when slaked lime is used as the first deacidifying agent for the first stage of deacidification treatment, the excess coefficient of the first deacidifying agent is 1.2-1.8.

[0090] The following examples illustrate this with specific flue gas treatment projects:

[0091] Example 2-1:

[0092] Flue gas conditions: A waste incineration project, flue gas flow rate: 100,000 Nm³ 3 / h; Original acidic pollutants include: SO2: 400mg / Nm 3 HCl: 800 mg / Nm 3 NOx: 200 mg / Nm 3 Dust concentration: 3000 mg / Nm³ 3 .

[0093] Export emission requirements: SO2: 10 mg / Nm³ 3 HCl: 10 mg / Nm 3 NOx: 50 mg / Nm 3 Dust: 5mg / Nm 3 .

[0094] In this embodiment, the denitrification process is performed after the first-stage dust removal.

[0095] A process for purifying flue gas containing highly acidic pollutants from waste incineration includes the following steps:

[0096] A1. The flue gas at 350℃ from the outlet of the waste heat boiler 11 is introduced into the first-stage dry reactor 1. Quicklime with a specific surface area >20㎡ / g is injected into the flue gas at an excess coefficient of 1.5 for the first-stage deacidification treatment. The inlet flue gas temperature of the first-stage dry reactor 1 is 350℃, the reactor flow rate is 10m / s, and the residence time is 1.3s. The reaction temperature of the first-stage deacidification treatment is 350℃.

[0097] A2. The first integrated dust removal and denitrification device 10 is used for the first stage of dust removal and denitrification treatment. The first integrated dust removal and denitrification device 10 is specifically a ceramic filter cartridge integrated dust removal and denitrification system.

[0098] The ceramic filter cartridge has a filtration velocity of 0.7 m / min; it collects the first fly ash from the first stage of dust removal and recycles it for the first stage of acid removal, with a first fly ash recycling ratio of 30 times.

[0099] The denitrification process uses 20% ammonia water as a reducing agent. After being evaporated by the evaporator, the 20% ammonia water enters the ammonia injection grid in the integrated inlet flue. The amount of ammonia injected is adjusted according to the actual nitrogen oxides and ammonia escape requirements for removal efficiency.

[0100] A3. High-temperature economizer 4 is used to cool the flue gas and recover waste heat. The flue gas inlet temperature of high-temperature economizer 4 is 340℃ and the flue gas outlet temperature is 160℃. The deaeration feedwater inlet temperature of high-temperature economizer 4 is 130℃ and the outlet water temperature is 240℃.

[0101] A4. The flue gas cooled by the high-temperature economizer 4 is introduced into the second-stage dry reactor 5. Hydrated lime with a specific surface area >15㎡ / g is injected into the flue gas at an excess coefficient of 1.3 for second-stage deacidification treatment. Activated carbon is also injected into the flue gas at a rate of 0.5kg per ton of waste incinerated to adsorb dioxins and heavy metals in the flue gas. The inlet flue gas temperature of the second-stage dry reactor 5 is 160℃, and the outlet flue gas temperature is 145℃ (after humidification of the second fly ash, the flue gas temperature decreases from 160℃ to 145℃). The flue gas velocity of the second-stage dry reactor 5 is 11m / s, and the flue gas residence time is 1.0s. Additionally, it should be noted that to prevent smoldering of the activated carbon, the proportion of activated carbon in the fly ash should not exceed 10%.

[0102] A5. The flue gas after the second-stage deacidification treatment is treated with a bag filter for second-stage dust removal, with a filtration velocity of 0.7 m / min. The second fly ash from the second-stage dust removal treatment is collected and recycled back to the second-stage deacidification, with a recycling ratio of 50 times. The second fly ash is also humidified, with a humidification range of 3-5%. After the second-stage dust removal treatment, the flue gas temperature is 145℃, and the flue gas has met the emission standards. It is then introduced into the chimney by an induced draft fan and discharged outside.

[0103] After the above purification process:

[0104] Tests showed that the SO2 content in the flue gas was 6 mg / Nm³. 3 HCl: 5 mg / Nm 3 NOx: 38 mg / Nm 3 Dust concentration: 1.8 mg / Nm³ 3 ;

[0105] The overall excess coefficient of hydrated lime is <1.5;

[0106] Fly ash production ≈ 1.5%;

[0107] In this embodiment, the SCR does not require steam heating, the high-temperature economizer outlet flue gas temperature is 160°C, and the power generation efficiency is approximately 23.9%. In contrast, in the conventional water-spray semi-dry acid removal process (Comparative Example 1), the boiler exhaust temperature is 190°C, the SCR requires steam heating, waste heat recovery is not considered, the chimney exhaust temperature is 180°C, and the power generation efficiency is approximately 21.2%. Therefore, compared to the conventional water-spray semi-dry acid removal process (Comparative Example 1), the power generation efficiency is increased by 2.7%.

[0108] Example 2-2:

[0109] Flue gas conditions: A waste incineration project, flue gas flow rate: 100,000 Nm³ 3 / h; Original acidic pollutants include: SO2: 400mg / Nm 3 HCl: 800 mg / Nm 3 NOx: 200 mg / Nm 3 Dust concentration: 3000 mg / Nm³ 3 .

[0110] Export emission requirements: SO2: 10 mg / Nm³ 3 HCl: 10 mg / Nm 3 NOx: 50 mg / Nm 3 Dust: 5mg / Nm 3 .

[0111] In this embodiment, the denitrification process is performed after the first-stage dust removal.

[0112] A process for purifying flue gas containing highly acidic pollutants from waste incineration includes the following steps:

[0113] A1. The flue gas at 300℃ from the outlet of the waste heat boiler 11 is introduced into the first-stage dry reactor 1. Quicklime with a specific surface area >20㎡ / g is injected into the flue gas at an excess coefficient of 1.6 for the first-stage deacidification treatment. The inlet flue gas temperature of the first-stage dry reactor 1 is 300℃, the reactor flow rate is 10m / s, and the residence time is 1.3s. The reaction temperature of the first-stage deacidification treatment is 300℃.

[0114] A2. The first integrated dust removal and denitrification device 10 is used for the first stage of dust removal and denitrification treatment. The first integrated dust removal and denitrification device 10 is specifically a ceramic filter cartridge integrated dust removal and denitrification system.

[0115] The ceramic filter cartridge has a filtration velocity of 0.7 m / min; it collects the first fly ash from the first stage of dust removal and recycles it for the first stage of acid removal, with a first fly ash recycling ratio of 30 times.

[0116] The denitrification process uses 20% ammonia water as a reducing agent. After being evaporated by the evaporator, the 20% ammonia water enters the ammonia injection grid in the integrated inlet flue. The amount of ammonia injected is adjusted according to the actual nitrogen oxides and ammonia escape requirements for removal efficiency.

[0117] A3. High-temperature economizer 4 is used to cool the flue gas and recover waste heat. The flue gas inlet temperature of high-temperature economizer 4 is 300℃ and the flue gas outlet temperature is 160℃. The deaeration feedwater inlet temperature of high-temperature economizer 4 is 130℃ and the outlet water temperature is 240℃.

[0118] A4. The flue gas cooled by the high-temperature economizer 4 is introduced into the second-stage dry reactor 5. Hydrated lime with a specific surface area >15㎡ / g is injected into the flue gas at an excess coefficient of 1.4 for second-stage deacidification treatment. Activated carbon is also injected into the flue gas at a rate of 0.5kg per ton of waste incinerated to adsorb dioxins and heavy metals in the flue gas. The inlet flue gas temperature of the second-stage dry reactor 5 is 160℃, and the outlet flue gas temperature is 145℃ (after humidification of the second fly ash, the flue gas temperature decreases from 160℃ to 145℃). The flue gas velocity of the second-stage dry reactor 5 is 11m / s, and the flue gas residence time is 1.0s. Additionally, it should be noted that to prevent smoldering of the activated carbon, the proportion of activated carbon in the fly ash should not exceed 10%.

[0119] A5. The flue gas after the second-stage deacidification treatment is treated with a bag filter for second-stage dust removal, with a filtration velocity of 0.7 m / min. The second fly ash from the second-stage dust removal treatment is collected and recycled back to the second-stage deacidification, with a recycling ratio of 70 times. The second fly ash is also humidified, with a humidification range of 3-5%. After the second-stage dust removal treatment, the flue gas temperature is 145℃, and the flue gas has met the emission standards. It is then introduced into the chimney by an induced draft fan and discharged outside.

[0120] After the above purification process:

[0121] Tests showed that the SO2 content in the flue gas was 5 mg / Nm³. 3 HCl: 3 mg / Nm 3 NOx: 40 mg / Nm 3 Dust: 2mg / Nm 3 ;

[0122] The overall excess coefficient of hydrated lime is <1.6;

[0123] Fly ash production ≈ 1.6%;

[0124] In this embodiment, the SCR does not require steam heating, the high-temperature economizer outlet flue gas temperature is 160°C, and the power generation efficiency is approximately 23.9%. In contrast, in the conventional water-spray semi-dry acid removal process (Comparative Example 1), the boiler exhaust temperature is 190°C, the SCR requires steam heating, waste heat recovery is not considered, the chimney exhaust temperature is 180°C, and the power generation efficiency is approximately 21.2%. Therefore, compared to the conventional water-spray semi-dry acid removal process (Comparative Example 1), the power generation efficiency is increased by 2.7%.

[0125] Examples 2-3:

[0126] Flue gas conditions: A waste incineration project, flue gas flow rate: 100,000 Nm³ 3 / h; Original acidic pollutants include: SO2: 600mg / Nm 3 HCl: 1200 mg / Nm 3 NOx: 200 mg / Nm 3 Dust concentration: 3000 mg / Nm³ 3 .

[0127] Export emission requirements: SO2: 10 mg / Nm³ 3 HCl: 10 mg / Nm 3 NOx: 50 mg / Nm 3 Dust: 5mg / Nm 3 .

[0128] In this embodiment, the denitrification process is performed after the second-stage dust removal.

[0129] A process for purifying flue gas containing highly acidic pollutants from waste incineration includes the following steps:

[0130] B1. The high-temperature flue gas from the outlet of the waste heat boiler 11 is introduced into the first-stage dry reactor 1. Quicklime with a specific surface area >20㎡ / g is injected into the flue gas at an excess coefficient of 1.8 to carry out the first-stage deacidification treatment. The inlet flue gas temperature of the first-stage dry reactor 1 is 350℃, the reactor flow rate is 10m / s, and the residence time is 1.3s. The reaction temperature of the first-stage deacidification treatment is 350℃.

[0131] B2. The flue gas after the first stage of acid removal treatment is treated with a ceramic cartridge dust removal system for the first stage of dust removal. The filtration velocity of the ceramic cartridge is 0.8 m / min. The first fly ash from the first stage of dust removal treatment is collected and recycled back to the first stage of acid removal. The recycling ratio of the first fly ash is 50 times.

[0132] B3. High-temperature economizer 4 is used to cool the flue gas and recover waste heat. The flue gas inlet temperature of high-temperature economizer 4 is 350℃ and the flue gas outlet temperature is 185℃. The deaeration feedwater inlet temperature of high-temperature economizer 4 is 130℃ and the outlet water temperature is 240℃.

[0133] B4. The cooled flue gas is introduced into the second-stage dry reactor 5. Ground sodium bicarbonate (particle size below 30 μm) is injected into the flue gas at an excess coefficient of 1.2, or high specific surface area hydrated lime (specific surface area above 40 m² / g) is injected into the flue gas at an excess coefficient of 1.3 for the second-stage deacidification treatment. Activated carbon is also injected into the flue gas (activated carbon injection amount < 0.5 kg / t of waste) to adsorb dioxins and heavy metals in the flue gas. The inlet flue gas temperature of the second-stage dry reactor 5 is 185℃, the flue gas flow rate in the reactor is 10 m / s, and the flue gas residence time is 1.0 s. Note that to prevent smoldering of activated carbon, the proportion of activated carbon in fly ash should not exceed 10%.

[0134] B5. The flue gas after the second stage of acid removal is treated with a bag filter for second stage dust removal. The bag filter has a filtration velocity of 0.8 m / min. The second fly ash from the second stage dust removal is collected and recycled back to the second stage of acid removal. The second fly ash recycling ratio is 20 times, and the flue gas outlet temperature is 180℃.

[0135] B6. The flue gas enters the SCR system. The denitrification process uses 20% ammonia water as a reducing agent. After evaporation in the evaporator, the 20% ammonia water enters the ammonia injection grid in the integrated inlet flue. The ammonia injection rate is adjusted according to the actual nitrogen oxide and ammonia escape requirements for removal efficiency. The flue gas temperature after SCR denitrification is approximately 175-180℃.

[0136] B7. The flue gas enters the low-temperature economizer 21 to cool down the denitrified flue gas and recover waste heat. After secondary waste heat utilization, the flue gas temperature is 130℃, and the flue gas has reached the emission standard. It is then introduced into the chimney by the induced draft fan and discharged outside.

[0137] After the above purification process:

[0138] Tests showed that the SO2 content in the flue gas was 6 mg / Nm³. 3 HCl: 3 mg / Nm 3 NOx: 42 mg / Nm 3 Dust concentration: 2.2 mg / Nm³ 3 ;

[0139] In step B1, slaked lime with a specific surface area > 20 m² / g is used, with an excess coefficient ≤ 1.8; in step B4, slaked lime with a specific surface area > 40 m² / g is used, with an excess coefficient ≤ 1.3; in step B4, baking soda with a particle size < 30 μm is used, with an excess coefficient ≤ 1.2.

[0140] Fly ash production ≈ 1.5%;

[0141] In this embodiment, the SCR does not require steam heating. The flue gas temperature at the outlet of the high-temperature economizer is 185°C. The flue gas enters the low-temperature economizer to cool the denitrified flue gas and recover waste heat. After secondary waste heat utilization, the flue gas temperature is 130°C, and the power generation efficiency is approximately 24.7%. In contrast, in the conventional water-spray semi-dry desulfurization process (Comparative Example 1), the boiler exhaust temperature is 190°C, the SCR requires steam heating, and waste heat recovery is not considered. The chimney exhaust temperature is 180°C, and the power generation efficiency is approximately 21.2%. Therefore, compared with the conventional water-spray semi-dry desulfurization process (Comparative Example 1), the power generation efficiency is increased by 3.5%.

[0142] Examples 2-4:

[0143] Flue gas conditions: A waste incineration project, flue gas flow rate: 100,000 Nm³ 3 / h; Original acidic pollutants include: SO2: 600mg / Nm 3 HCl: 1200 mg / Nm 3 NOx: 200 mg / Nm 3 Dust concentration: 3000 mg / Nm³ 3 .

[0144] Export emission requirements: SO2: 10 mg / Nm³ 3 HCl: 10 mg / Nm 3 NOx: 50 mg / Nm 3 Dust: 5mg / Nm 3 .

[0145] In this embodiment, the denitrification process is performed after the second-stage dust removal.

[0146] A process for purifying flue gas containing highly acidic pollutants from waste incineration includes the following steps:

[0147] B1. The high-temperature flue gas from the outlet of the waste heat boiler 11 is introduced into the first-stage dry reactor 1. Quicklime with a specific surface area >20㎡ / g is injected into the flue gas at an excess coefficient of 1.6 for the first-stage deacidification treatment. The inlet flue gas temperature of the first-stage dry reactor 1 is 300℃, the reactor flow rate is 10m / s, and the residence time is 1.3s. The reaction temperature of the first-stage deacidification treatment is 300℃.

[0148] B2. The flue gas after the first stage of acid removal treatment is treated with a ceramic cartridge dust removal system for the first stage of dust removal. The filtration velocity of the ceramic cartridge is 0.8 m / min. The first fly ash from the first stage of dust removal treatment is collected and recycled back to the first stage of acid removal. The recycling ratio of the first fly ash is 50 times.

[0149] B3. High-temperature economizer 4 is used to cool the flue gas and recover waste heat. The flue gas inlet temperature of high-temperature economizer 4 is 300℃ and the flue gas outlet temperature is 185℃. The deaeration feedwater inlet temperature of high-temperature economizer 4 is 130℃ and the outlet water temperature is 240℃.

[0150] B4. The cooled flue gas is introduced into the second-stage dry reactor 5. Ground baking soda (particle size below 30um) is injected into the flue gas at an excess coefficient of 1.2, or high specific surface area hydrated lime (specific surface area above 40㎡ / g) is injected into the flue gas at an excess coefficient of 1.4 for second-stage deacidification treatment. Activated carbon is also injected into the flue gas (activated carbon injection amount < 0.5kg / t of waste) to adsorb dioxins and heavy metals in the flue gas. The inlet flue gas temperature of the second-stage dry reactor 5 is 185℃, the flue gas flow rate in the reactor is 10m / s, and the flue gas residence time is 1.0s. It should be noted that in order to prevent smoldering of activated carbon, the proportion of activated carbon in fly ash should not exceed 10%.

[0151] B5. The flue gas after the second stage of acid removal is treated with a bag filter for second stage dust removal. The bag filter has a filtration velocity of 0.8 m / min. The second fly ash from the second stage dust removal is collected and recycled back to the second stage of acid removal. The second fly ash recycling ratio is 40 times, and the flue gas outlet temperature is 180℃.

[0152] B6. The flue gas enters the SCR system. The denitrification process uses 20% ammonia water as a reducing agent. After evaporation in the evaporator, the 20% ammonia water enters the ammonia injection grid in the integrated inlet flue. The ammonia injection rate is adjusted according to the actual nitrogen oxide and ammonia escape requirements for removal efficiency. The flue gas temperature after SCR denitrification is approximately 175-180℃.

[0153] B7. The flue gas enters the low-temperature economizer 21 to cool down the denitrified flue gas and recover waste heat. After secondary waste heat utilization, the flue gas temperature is 130℃, and the flue gas has reached the emission standard. It is then introduced into the chimney by the induced draft fan and discharged outside.

[0154] After the above purification process:

[0155] Tests showed that the SO2 content in the flue gas was 5 mg / Nm³. 3 HCl: 5 mg / Nm 3 NOx: 45 mg / Nm 3 Dust concentration: 1.5 mg / Nm³ 3 ;

[0156] In step B1, slaked lime with a specific surface area > 20 m² / g is used, with an excess coefficient ≤ 1.6; in step B4, slaked lime with a specific surface area > 40 m² / g is used, with an excess coefficient ≤ 1.4; in step B4, baking soda with a particle size < 30 μm is used, with an excess coefficient ≤ 1.2.

[0157] Fly ash production ≈ 1.6%;

[0158] In this embodiment, the SCR does not require steam heating. The flue gas temperature at the outlet of the high-temperature economizer is 185°C. The flue gas enters the low-temperature economizer to cool the denitrified flue gas and recover waste heat. After secondary waste heat utilization, the flue gas temperature is 130°C, and the power generation efficiency is approximately 24.7%. In contrast, in the conventional water-spray semi-dry desulfurization process (Comparative Example 1), the boiler exhaust temperature is 190°C, the SCR requires steam heating, and waste heat recovery is not considered. The chimney exhaust temperature is 180°C, and the power generation efficiency is approximately 21.2%. Therefore, compared with the conventional water-spray semi-dry desulfurization process (Comparative Example 1), the power generation efficiency is increased by 3.5%.

[0159] II. Comparative Example:

[0160] Flue gas conditions: A waste incineration project, flue gas flow rate: 100,000 Nm³ 3 / h; Original acidic pollutants include: SO2: 400mg / Nm 3 HCl: 800 mg / Nm 3 NOx: 200 mg / Nm 3 Dust concentration: 3000 mg / Nm³ 3 .

[0161] Export emission requirements: SO2: 10 mg / Nm³ 3 HCl: 10 mg / Nm 3 NOx: 50 mg / Nm 3 Dust: 5mg / Nm 3 .

[0162] Comparative Example 1:

[0163] Conventional water spray semi-dry deacidification: SDA rotary spray semi-dry deacidification (using slaked lime) + dry deacidification (using slaked lime) + bag filter + SGH heater + SCR.

[0164] After conventional water spray semi-dry deacidification treatment as described in Comparative Example 1:

[0165] Tests showed that the SO2 content in the flue gas was 7 mg / Nm³. 3 HCl: 4 mg / Nm 3 NOx: 40 mg / Nm 3 Dust: 2mg / Nm 3 ;

[0166] The overall excess coefficient of hydrated lime is >2.5;

[0167] Fly ash production ≈ 3%;

[0168] The power generation efficiency is approximately 21.2%.

[0169] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any changes or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in the present invention should be included within the scope of protection of the present invention.

Claims

1. A process for purifying flue gas containing high-acid pollutants from waste incineration, characterized in that, A purification system is used to purify flue gas. The purification system includes the following components connected in sequence along the flue gas flow direction: The first-stage dry reactor has a first flue gas inlet pipe and a first deacidifying agent injection assembly is installed on the first flue gas inlet pipe. The first-stage dry reactor is used to receive high-temperature flue gas and perform first-stage deacidification treatment. First-stage dust removal device; High temperature economizer; The second-stage dry reactor has a second flue gas inlet pipe, and the second flue gas inlet pipe is equipped with a second deacidifying agent injection assembly and an activated carbon injection assembly. The second-stage dry reactor is used to receive flue gas cooled by a high-temperature economizer and to perform second-stage deacidification treatment and removal of dioxins and heavy metals. Second-stage dust removal device; Among them, a first fly ash recycling component is provided between the first-stage dry reactor and the first-stage dust removal device for recycling the first fly ash collected by the first-stage dust removal device back to the first-stage deacidification treatment. Between the second-stage dry reactor and the second-stage dust removal device, there is also a second fly ash recycling component for recycling the second fly ash collected by the second-stage dust removal device back to the second-stage deacidification treatment, and a fly ash humidification component for humidifying the second fly ash. It also includes a denitrification device for treating flue gas, wherein the denitrification device is configured in one of the following two ways: Method 1: The denitrification device is connected in series between the first-stage dust removal device and the high-temperature economizer along the flue gas flow direction; Method 2: The denitrification device is connected in series downstream of the second-stage dust removal device along the flue gas flow direction; The purification system described above is used to purify flue gas, comprising the following steps: High-temperature flue gas is introduced into the first-stage dry reactor, and the first deacidifying agent is injected into the flue gas to carry out the first-stage deacidification treatment. The reaction temperature of the first-stage deacidification treatment is 300-350℃. The flue gas after the first stage of deacidification treatment is subjected to the first stage of dust removal device for the first stage of dust removal treatment; the first fly ash from the first stage of dust removal treatment is collected and recycled back to the first stage of deacidification treatment; The flue gas is introduced into a denitrification unit for denitrification treatment; A high-temperature economizer is used to cool the flue gas and recover waste heat, reducing the flue gas temperature to 145-200℃; The cooled flue gas is introduced into the second-stage dry reactor, where a second deacidifying agent and activated carbon are injected into the flue gas for second-stage deacidification treatment and removal of dioxins and heavy metals. The flue gas after the second-stage deacidification treatment is subjected to a second-stage dust removal device for second-stage dust removal treatment; the second fly ash from the second-stage dust removal treatment is collected, and the second fly ash is humidified and recycled back to the second-stage deacidification treatment. The denitrification treatment is performed after the first-stage dust removal; or, the denitrification treatment is performed after the second-stage dust removal.

2. The process for purifying highly acidic pollutant flue gas from waste incineration according to claim 1, characterized in that, When the denitrification device is located downstream of the second-stage dust removal device, the denitrification process is carried out after the second-stage dust removal. It also includes a low-temperature economizer connected in series downstream of the denitrification device. Before the flue gas is discharged, the low-temperature economizer is used to cool the flue gas and recover waste heat, reducing the flue gas temperature to below 130°C.

3. The waste incineration high-acid pollutant flue gas purification process according to claim 1, characterized in that, The first fly ash circulation assembly includes a first fly ash collection pipeline, a first fly ash circulation fluidized bed located at the end of the first fly ash collection pipeline, and a first fly ash conveying pipeline connected to the first fly ash circulation fluidized bed. The other end of the first fly ash conveying pipeline is connected to the first-stage dry reactor. A first fly ash discharge pipe is provided at the bottom of the first fly ash circulation fluidized bed. And / or, the second fly ash circulation assembly includes a second fly ash collection pipeline, a second fly ash circulation fluidized bed located at the end of the second fly ash collection pipeline, and a second fly ash conveying pipeline connected to the second fly ash circulation fluidized bed, the other end of the second fly ash conveying pipeline being connected to a second-stage dry reactor; a second fly ash discharge pipe is provided at the bottom of the second fly ash circulation fluidized bed; the fly ash humidification assembly is connected to the second fly ash conveying pipeline of the second fly ash circulation assembly.

4. The process for purifying highly acidic pollutant flue gas from waste incineration according to claim 1, characterized in that, When the denitrification device is installed between the first-stage dust removal device and the high-temperature economizer: The first stage of dust removal uses an electrostatic precipitator, metal filter bags, or ceramic filter cartridges, followed by high-temperature SCR denitrification treatment of the flue gas after the first stage of dust removal; or, the first stage of dust removal and denitrification treatment are combined using an integrated dust removal and denitrification device with metal catalytic filter bags or catalytic ceramic filter cartridges. The second stage of dust removal uses a bag filter; When the denitrification unit is located downstream of the second-stage dust removal unit: The first stage of dust removal uses electrostatic precipitators, metal filter bags, or ceramic filter cartridges; The second-stage dust removal uses a bag filter, followed by low-temperature SCR denitrification treatment; alternatively, the second-stage dust removal and denitrification treatments are combined using an integrated dust removal and denitrification device with catalytic filter bags or catalytic ceramic filter cartridges.

5. The process for purifying high-acidity pollutant flue gas from waste incineration according to claim 1, characterized in that, When denitrification is performed after the second-stage dust removal, a high-temperature economizer is used to reduce the flue gas temperature to 180-195℃. The second denitrification agent includes sodium bicarbonate or a specific surface area greater than 40m². 2 / g of high-ratio slaked lime; when sodium bicarbonate is used as the second deacidifying agent for the second-stage deacidification treatment, the excess coefficient of the second deacidifying agent is 1.05-1.2; when high-ratio slaked lime is used as the second deacidifying agent for the second-stage deacidification treatment, the excess coefficient of the second deacidifying agent is 1.2-1.8; And / or, when the denitrification treatment is carried out after the second-stage dust removal, the inlet flue gas temperature of the second-stage dry reactor is 180-195℃, the flue gas velocity of the reactor is 10-13m / s, and the flue gas residence time is 0.8-1.2s.

6. The process for purifying high-acidity pollutant flue gas from waste incineration according to claim 1, characterized in that, When the denitrification treatment is carried out after the first-stage dust removal, a high-temperature economizer is used to reduce the temperature of the flue gas to 155-165℃. The second deacidification agent includes slaked lime. When slaked lime is used as the second deacidification agent for the second-stage deacidification treatment, the excess coefficient of the second deacidification agent is 1.2-1.

5. And / or, when the denitrification treatment is carried out after the first-stage dust removal, the inlet flue gas temperature of the second-stage dry reactor is 155-165℃, and the outlet flue gas temperature is not higher than 150℃; the flue gas velocity of the reactor is 10-13m / s, and the flue gas residence time is 0.8-1.2s.

7. The waste incineration high-acid pollutant flue gas purification process according to claim 1, characterized in that, The recycling rate of the first fly ash is 20-80 times; And / or, the circulation ratio of the second fly ash is 20-80 times; when the second deacidifying agent is slaked lime, the second fly ash is humidified, and the humidification range of the second fly ash is 1%-5%.

8. The waste incineration high-acid pollutant flue gas purification process according to claim 1, characterized in that, During the first-stage deacidification treatment, the inlet flue gas temperature of the first-stage dry reactor is 300-350℃, the reactor flow rate is 8-12m / s, and the residence time is 1.0-1.5s. And / or, the first deacidifying agent includes slaked lime, and when slaked lime is used as the first deacidifying agent for the first stage of deacidification treatment, the excess coefficient of the first deacidifying agent is 1.2-1.8.

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