A waste incineration flue gas low-temperature plasma coupling denitration system

Abstract

This invention relates to the field of waste incineration flue gas waste heat recovery technology, and discloses a waste incineration flue gas low-temperature plasma coupled denitrification and synergistic waste heat utilization system, comprising: a low-temperature plasma pre-oxidation unit equipped with a low-temperature plasma generator, the low-temperature plasma generator being equipped with a high-voltage pulse electrical terminal, an internal electrode group, and a flue gas inlet and outlet; a low-temperature SCR deep denitrification unit equipped with a low-temperature SCR reactor, the low-temperature SCR reactor being fixedly equipped with a vanadium-titanium-based catalyst layer; a flue gas waste heat recovery and closed-loop utilization unit equipped with a high-efficiency waste heat exchanger, the high-efficiency waste heat exchanger being equipped with a flue gas inlet and outlet, a feed water inlet, and a feed water outlet; and a flue gas inlet of a subsequent purification and emission unit being sealed to the flue gas outlet of the high-efficiency waste heat exchanger. This invention solves the problems of existing technologies such as SCR denitrification requiring additional heating, high energy consumption, high operating costs, unstable denitrification efficiency, secondary pollution caused by ammonia escape, and the independent setup and poor synergy between the denitrification system and the waste heat recovery system.

Description

Technical Field

[0001] This invention relates to the field of waste heat recovery technology from waste incineration flue gas, and in particular to a low-temperature plasma-coupled denitrification and synergistic waste heat utilization system for waste incineration flue gas. Background Technology

[0002] In the field of industrial waste gas treatment, especially in the waste incineration industry, flue gas denitrification is a crucial step in protecting the ecological environment and human health. With increasingly stringent global environmental regulations, countries are placing greater emphasis on nitrogen oxides (NOx). With emission limits being continuously lowered, waste incineration plants, as... As a major source of emissions, it urgently needs the support of efficient and low-consumption denitrification technologies.

[0003] Currently, the mainstream denitrification technology is selective catalytic reduction (SCR) technology, among which high-temperature SCR technology (reaction temperature 300-400℃) is the most widely used. However, it relies on a high-temperature flue gas environment and requires a large amount of electrical or fossil fuel energy to maintain the reaction conditions, resulting in high energy consumption. Low-temperature SCR technology (reaction temperature 150-250℃) has some optimization in energy consumption, but it faces technical bottlenecks such as catalyst activity being easily affected by flue gas composition, unstable denitrification efficiency, and ammonia escape. In addition, traditional denitrification systems are mostly designed with a single purification function, and a large amount of waste heat contained in the flue gas is not effectively recovered, leading to energy waste and low overall system energy efficiency.

[0004] In recent years, the coupling of low-temperature plasma technology with catalytic technology has become a hot research topic in the field of denitrification. Low-temperature plasma can generate active particles at relatively low temperatures, enabling rapid oxidation. This creates favorable conditions for subsequent catalytic removal, but the industrial application of this coupling technology still faces problems such as high energy supply costs and poor synergy between waste heat recovery and the denitrification process. Meanwhile, the industry's demand for integrated "denitrification-waste heat utilization" systems is increasingly urgent. How to achieve the organic unity of improved denitrification efficiency, reduced energy consumption, and efficient waste heat recovery has become the core development direction and a key issue that urgently needs to be addressed in the field of waste incineration flue gas treatment technology. Summary of the Invention

[0005] This invention aims to provide a low-temperature plasma-coupled denitrification and waste heat utilization system for waste incineration flue gas, in order to solve the problems of existing technologies such as SCR denitrification requiring additional heating, high energy consumption, high operating costs, unstable denitrification efficiency, secondary pollution caused by ammonia escape, and poor synergy between the denitrification system and the waste heat recovery system.

[0006] To achieve the above objectives, the present invention provides the following system and method:

[0007] This invention provides a low-temperature plasma-coupled denitrification and waste heat utilization system for waste incineration flue gas, the system comprising:

[0008] Along the flow direction of waste incineration flue gas, a low-temperature plasma pre-oxidation unit, a low-temperature SCR deep denitrification unit, a flue gas waste heat recovery and closed-loop utilization unit, and a subsequent purification and emission unit are connected in series through seamlessly welded stainless steel flue gas pipelines.

[0009] The low-temperature plasma pre-oxidation unit is equipped with a low-temperature plasma generator, which includes a high-voltage pulse electrical terminal, an internal electrode assembly, and a flue gas inlet and outlet. The flue gas inlet is sealed to a waste incineration flue gas pipeline with a temperature range of 180-220°C. The low-temperature SCR deep denitrification unit is equipped with a low-temperature SCR reactor. A vanadium-titanium-based catalyst layer is fixed inside the reactor by a metal support, and the activity temperature range of the vanadium-titanium-based catalyst layer is 180-220°C. The flue gas waste heat recovery and closed-loop utilization unit is equipped with a high-efficiency waste heat exchanger, which includes a flue gas inlet and outlet, a feedwater inlet, and a feedwater outlet. The feedwater inlet is sealed to the boiler feedwater system's outlet pipe, and the feedwater outlet is sealed to the boiler system's return water pipe. The flue gas inlet of the subsequent purification and emission unit is sealed to the flue gas outlet of the high-efficiency waste heat exchanger via a stainless steel flue gas pipeline.

[0010] Preferably, the internal electrode group of the low-temperature plasma generator has a needle-plate electrode structure, and the high-voltage pulse terminal is electrically connected to an external high-voltage pulse power supply. The strong electric field region formed by the internal electrode group within the generator cavity completely covers the flue gas flow cross-section. When the waste incineration flue gas flows through the strong electric field region, the flue gas contains... , , and Gas molecules undergo ionization and dissociation reactions, generating •OH hydroxyl radicals. At least one highly reactive particle selected from ozone, O-oxygen atoms, and N-nitrogen atoms, said highly reactive particle oxidizes low-valence NO in flue gas to... , At least one high-valence nitrogen oxide.

[0011] Preferably, the low-temperature SCR reactor has a reducing agent inlet on the side wall of the cylinder, and the reducing agent inlet is sealed and connected to an ammonia injection pipe. The ammonia injection pipe extends into the cavity of the low-temperature SCR reactor and its injection end is located at the front end of the flue gas flow of the vanadium-titanium-based catalyst layer. The outer wall of the low-temperature SCR reactor has no heat replenishment jacket or external heat replenishment pipeline.

[0012] Preferably, the vanadium-titanium-based catalyst layer has a honeycomb-like multi-layered porous structure, with pre-reserved flue gas guiding channels between the layers. The vanadium-titanium-based catalyst layer facilitates the flow of flue gas... The removal efficiency is ≥98%, the selective catalytic reduction reaction process in the low-temperature SCR reactor has no ammonia escape, and the pore size of the vanadium-titanium-based catalyst layer is adapted to the flow rate of the waste incineration flue gas.

[0013] Preferably, the pore size of the vanadium-titanium based catalyst layer is 3-5 mm, the inner wall of the pores is loaded with vanadium-titanium active components, the metal support is a hollow mesh structure, and it is welded and fixed to the inner wall of the cylinder of the low-temperature SCR reactor.

[0014] Preferably, the high-efficiency waste heat exchanger is a shell-and-tube flue gas-water heat exchanger structure, which has a flue gas flow chamber and a feedwater flow chamber inside. The flue gas flow chamber is sealed and connected to the flue gas outlet of the low-temperature SCR reactor. The inlet of the feedwater flow chamber is sealed and connected to the outlet pipe of the boiler feedwater system. The outlet of the feedwater flow chamber is sealed and connected to the return water pipe of the boiler system. The medium-temperature waste heat of the flue gas after denitrification is transferred to the feedwater in the feedwater flow chamber through the high-efficiency waste heat exchanger. The feedwater that has absorbed the waste heat flows back to the boiler system through the return water pipe of the boiler system.

[0015] Preferably, the flue gas flow chamber and the feed water flow chamber of the high-efficiency waste heat exchanger are arranged in a staggered manner. The inner wall of the flue gas flow chamber is provided with arrayed turbulence protrusions, and the feed water flow chamber is provided with spiral guide vanes. Temperature monitoring interfaces are welded to both the feed water inlet and the feed water outlet of the feed water flow chamber, and pressure monitoring interfaces are welded to both the flue gas inlet and the flue gas outlet of the flue gas flow chamber.

[0016] Preferably, the subsequent purification and emission unit is provided with a dry reactor and a bag filter in sequence along the flue gas flow direction. The dry reactor is sealed to the flue gas outlet of the high-efficiency waste heat exchanger through the stainless steel flue gas pipeline. The top of the dry reactor is provided with a lime feeding port, and the cavity is provided with a stirring and dispersing paddle. The cavity of the bag filter is provided with a fiberglass filter bag assembly and a cleaning jet pipe assembly. The temperature of the flue gas after heat exchange in the high-efficiency waste heat exchanger when it enters the dry reactor is 145°C.

[0017] Preferably, the lime feed port of the dry reactor is sealed to an external screw feeder; the stirring and dispersing paddle is located above the flue gas inlet of the dry reactor; the cleaning jet pipe assembly of the bag filter is arranged parallel to the array direction of the fiberglass filter bag assembly, and the jet nozzles are directly opposite the opening end of the filter bags; the flue gas outlet of the bag filter is sealed to the exhaust chimney through a stainless steel flue gas pipeline; both the dry reactor and the bag filter are provided with a conical ash collection hopper at the bottom, and an ash discharge valve is provided at the bottom of the ash collection hopper.

[0018] Preferably, the system is an integrated skid-mounted structure, in which the equipment bodies of the low-temperature plasma pre-oxidation unit, the low-temperature SCR deep denitrification unit, the flue gas waste heat recovery and closed-loop utilization unit, and the subsequent purification and emission unit are all fixedly installed on the same steel structure base, and the control valves and instrument interfaces of each unit are integrated on the operation panel on one side of the steel structure base.

[0019] The beneficial effects of this invention are reflected in:

[0020] 1. Highly efficient and stable denitrification: Through low-temperature plasma pre-oxidation upgrading + low-temperature SCR deep reduction, it is adapted to waste incineration flue gas. Removal efficiency ≥98%, no ammonia escape, meeting stringent emission standards;

[0021] 2. Significantly reduced energy consumption: Utilizing the temperature of the flue gas itself, no external heating is required, resulting in a substantial reduction in denitrification energy consumption;

[0022] 3. High-efficiency waste heat recovery: heat exchange efficiency ≥90%, boiler feedwater temperature rise ≥30℃, and energy utilization rate improved;

[0023] 4. System Synergistic Efficiency: The integrated series design of denitrification and waste heat recovery is compact, efficient, and achieves the dual goals of purification and energy saving. It has a small footprint, simple process, and improves overall energy efficiency by more than 5%.

[0024] 5. Reduced operation and maintenance costs: Designed for the high dust, high humidity, and complex flue gas of waste incineration, the catalyst has a longer lifespan and more stable operation. The catalyst is resistant to poisoning and has an extended lifespan, reducing replacement and maintenance costs. Attached Figure Description

[0025] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the accompanying drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. In all the drawings, similar elements or parts are generally identified by similar reference numerals. In the drawings, the elements or parts are not necessarily drawn to scale.

[0026] Figure 1 This is a schematic diagram of a waste incineration flue gas low-temperature plasma coupling denitrification and waste heat utilization system provided in an embodiment of the present invention. Detailed Implementation

[0027] To enable those skilled in the art to better understand the present invention, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0028] The terms "first," "second," etc., used in the specification, claims, and accompanying drawings of this invention are used to distinguish different objects, not to describe a specific order. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover non-exclusive inclusion. For example, a process, method, apparatus, product, or end that includes a series of steps or units is not limited to the listed steps or units, but may optionally include steps or units not listed, or may optionally include other steps or units inherent to these processes, methods, products, or ends.

[0029] In this document, the term "embodiment" means that a particular feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of the invention. The appearance of this phrase in various places throughout the specification does not necessarily refer to the same embodiment, nor is it a separate or alternative embodiment mutually exclusive with other embodiments. It will be explicitly and implicitly understood by those skilled in the art that the embodiments described herein can be combined with other embodiments.

[0030] Currently, the mainstream denitrification technology is selective catalytic reduction (SCR) technology, among which high-temperature SCR technology (reaction temperature 300-400℃) is the most widely used. However, it relies on a high-temperature flue gas environment and requires a large amount of electrical or fossil fuel energy to maintain the reaction conditions, resulting in high energy consumption. Low-temperature SCR technology (reaction temperature 150-250℃) has some optimization in energy consumption, but it faces technical bottlenecks such as catalyst activity being easily affected by flue gas composition, unstable denitrification efficiency, and ammonia escape. In addition, traditional denitrification systems are mostly designed with a single purification function, and a large amount of waste heat contained in the flue gas is not effectively recovered, leading to energy waste and low overall system energy efficiency.

[0031] In recent years, the coupling of low-temperature plasma technology with catalytic technology has become a hot research topic in the field of denitrification. Low-temperature plasma can generate active particles at relatively low temperatures, enabling rapid oxidation. This creates favorable conditions for subsequent catalytic removal, but the industrial application of this coupling technology still faces problems such as high energy supply costs and poor synergy between waste heat recovery and the denitrification process. Meanwhile, the industry's demand for integrated "denitrification-waste heat utilization" systems is increasingly urgent. How to achieve the organic unity of improved denitrification efficiency, reduced energy consumption, and efficient waste heat recovery has become the core development direction and a key issue that urgently needs to be addressed in the field of waste incineration flue gas treatment technology.

[0032] This invention aims to provide a low-temperature plasma-coupled denitrification and waste heat utilization system for waste incineration flue gas, in order to solve the problems of existing technologies such as SCR denitrification requiring additional heating, high energy consumption, high operating costs, unstable denitrification efficiency, secondary pollution caused by ammonia escape, and poor synergy between the denitrification system and the waste heat recovery system.

[0033] like Figure 1 As shown in the figure, a specific embodiment of the present invention provides a low-temperature plasma-coupled denitrification and waste heat utilization system for waste incineration flue gas, the system comprising the following components:

[0034] Along the flow direction of waste incineration flue gas, a low-temperature plasma pre-oxidation unit, a low-temperature SCR deep denitrification unit, a flue gas waste heat recovery and closed-loop utilization unit, and a subsequent purification and emission unit are connected in series through seamlessly welded stainless steel flue gas pipelines.

[0035] The low-temperature plasma pre-oxidation unit is equipped with a low-temperature plasma generator. The generator includes a high-voltage pulse electrical terminal, an internal electrode assembly, and flue gas inlet and outlet. The flue gas inlet is sealed to a 180-220℃ waste incineration flue gas pipeline. The internal electrode assembly of the low-temperature plasma generator has a needle-plate electrode structure. The high-voltage pulse electrical terminal is electrically connected to an external high-voltage pulse power supply. The strong electric field region formed by the internal electrode assembly within the generator cavity completely covers the flue gas flow cross-section. When the waste incineration flue gas flows through the strong electric field region, the flue gas... , , and Gas molecules undergo ionization and dissociation reactions, generating •OH hydroxyl radicals. At least one highly reactive particle selected from ozone, O-oxygen atoms, and N-nitrogen atoms, which oxidizes low-valence NO in flue gas to... , At least one high-valence nitrogen oxide;

[0036] The low-temperature SCR deep denitrification unit is equipped with a low-temperature SCR reactor. A vanadium-titanium-based catalyst layer is fixed inside the reactor by a metal support. The activity temperature range of the vanadium-titanium-based catalyst layer is 180-220℃. A reducing agent inlet is opened on the side wall of the reactor shell, and the reducing agent inlet is sealed and connected to an ammonia injection pipe. The ammonia injection pipe extends into the reactor cavity, and its injection end is located at the front end of the flue gas flow path of the vanadium-titanium-based catalyst layer. The outer wall of the low-temperature SCR reactor has no heat supply jacket or external heat supply pipeline. The vanadium-titanium-based catalyst layer has a honeycomb-like multi-layered porous structure, with pre-reserved flue gas guiding channels between layers. The vanadium-titanium-based catalyst layer... The removal efficiency is ≥98%. There is no ammonia escape during the selective catalytic reduction reaction process in the low-temperature SCR reactor. The pore size of the vanadium-titanium-based catalyst layer is adapted to the flow rate of the waste incineration flue gas. The pore size of the vanadium-titanium-based catalyst layer is 3-5mm. The inner wall of the pore is loaded with vanadium-titanium active components. The metal support is a hollow grid structure and is welded and fixed to the inner wall of the cylinder of the low-temperature SCR reactor.

[0037] The flue gas waste heat recovery and closed-loop utilization unit is equipped with a high-efficiency waste heat exchanger. The high-efficiency waste heat exchanger has a flue gas inlet and outlet, a feedwater inlet, and a feedwater outlet. The feedwater inlet is sealed to the outlet pipe of the boiler feedwater system, and the feedwater outlet is sealed to the return water pipe of the boiler system. The high-efficiency waste heat exchanger is a shell-and-tube flue gas-water heat exchange structure, with an internal flue gas flow chamber and a feedwater flow chamber. The flue gas flow chamber is sealed to the flue gas outlet of the low-temperature SCR reactor, the feedwater inlet of the feedwater flow chamber is sealed to the outlet pipe of the boiler feedwater system, and the feedwater outlet of the feedwater flow chamber is sealed to the boiler... The system's return water pipe is sealed. The medium-temperature waste heat of the flue gas after denitrification is transferred to the feed water in the feed water flow chamber through a high-efficiency waste heat exchanger. The feed water, after absorbing waste heat, flows back to the boiler system through the boiler system's return water pipe. The flue gas flow chamber and feed water flow chamber of the high-efficiency waste heat exchanger are arranged in a staggered manner. The inner wall of the flue gas flow chamber is equipped with arrayed turbulence protrusions, and the feed water flow chamber is equipped with spiral guide vanes. Temperature monitoring interfaces are welded to both the feed water inlet and outlet of the feed water flow chamber, and pressure monitoring interfaces are welded to both the flue gas inlet and outlet of the flue gas flow chamber.

[0038] The flue gas inlet of the subsequent purification and emission unit is sealed to the flue gas outlet of the high-efficiency waste heat exchanger via a stainless steel flue gas pipeline. The subsequent purification and emission unit is equipped with a dry reactor and a bag filter sequentially along the flue gas flow direction. The dry reactor is sealed to the flue gas outlet of the high-efficiency waste heat exchanger via a stainless steel flue gas pipeline. A lime feed port is located at the top of the dry reactor, and a stirring and dispersing paddle is installed inside the chamber. The bag filter chamber contains fiberglass filter bags and a cleaning jet assembly. The temperature of the flue gas entering the dry reactor after heat exchange in the high-efficiency waste heat exchanger is 145℃. The lime feed port of the dry reactor is sealed to an external screw feeder, and the stirring and dispersing paddle is located within the dry reactor. Above the flue gas inlet of the dust collector, the cleaning jet pipes of the bag filter are arranged parallel to the array direction of the fiberglass filter bag assembly, and the jet nozzles are directly opposite the opening end of the filter bag. The flue gas outlet of the bag filter is sealed to the exhaust chimney through a stainless steel flue gas pipeline. Both the dry reactor and the bag filter are equipped with conical ash collection hoppers at the bottom, and ash discharge valves are installed at the bottom of the ash collection hoppers. The system is an integrated skid-mounted structure. The equipment bodies of the low-temperature plasma pre-oxidation unit, the low-temperature SCR deep denitrification unit, the flue gas waste heat recovery and closed-loop utilization unit, and the subsequent purification and emission unit are all fixedly installed on the same steel structure base. The control valves and instrument interfaces of each unit are integrated into the operation panel on one side of the steel structure base.

[0039] Example 1

[0040] This invention provides a low-temperature plasma-coupled denitrification and waste heat utilization system for waste incineration flue gas, applicable to, in conjunction with the following appendix Figure 1 The specific working process and implementation details of this system are explained in detail:

[0041] System overall layout

[0042] The waste incineration flue gas low-temperature plasma coupled denitrification and waste heat utilization system in this embodiment is an integrated skid-mounted structure. The equipment bodies of the low-temperature plasma pre-oxidation unit, the low-temperature SCR deep denitrification unit, the flue gas waste heat recovery and closed-loop utilization unit, and the subsequent purification and emission unit are all fixedly installed on the same steel structure base by bolts. The units are connected in series by seamless welding of stainless steel flue gas pipelines. The control valves such as ball valves and butterfly valves of each unit, as well as the instrument interfaces of temperature sensors and pressure sensors, are all integrated into the operation panel on one side of the steel structure base, which is convenient for operators to centrally monitor and operate. The overall system footprint is reduced by more than 40% compared with the traditional split system, and it can be directly transported to the waste incineration plant site for installation, which greatly shortens the construction period.

[0043] Operation process of the low-temperature plasma pre-oxidation unit

[0044] The flue gas generated by the waste incinerator is cooled by the waste heat boiler to form waste incineration flue gas with a temperature of 180-220℃. This flue gas is sealed and transported to the flue gas inlet of the low-temperature plasma generator in the low-temperature plasma pre-oxidation unit through a stainless steel flue gas pipeline. An external high-voltage pulse power supply is electrically connected to the high-voltage pulse electrical terminal of the low-temperature plasma generator to supply power to the needle-plate electrode group inside the generator. The needle-plate electrode group forms a strong electric field in the generator cavity, and the strong electric field area completely covers the flue gas flow section to ensure that the flue gas is in full contact with the strong electric field.

[0045] When the flue gas from waste incineration flows through a region with a strong electric field, the flue gas contains... , , and When gas molecules are bombarded by high-energy electrons, they undergo ionization and dissociation reactions, breaking the chemical bonds of the gas molecules and generating ·OH hydroxyl radicals. The gas contains various highly reactive particles, including ozone, O (oxygen) atoms, and N (nitrogen) atoms. These particles possess extremely strong oxidizing capabilities and can rapidly oxidize low-valence NO in flue gas, which is difficult to reduce catalytically. , High-valence nitrogen oxides create the necessary conditions for subsequent low-temperature SCR deep denitrification.

[0046] Operation process of low-temperature SCR deep denitrification unit

[0047] After the flue gas containing high-valence nitrogen oxides is discharged from the flue gas outlet of the low-temperature plasma generator, it enters the low-temperature SCR reactor of the low-temperature SCR deep denitrification unit through a stainless steel flue gas pipeline. The cylinder side wall of the low-temperature SCR reactor has a reducing agent inlet. The ammonia injection pipe sealed to the inlet extends into the reactor cavity, and the injection end is located at the front end of the flue gas flow of the vanadium-titanium-based catalyst layer. Ammonia gas is sprayed into the reactor in an atomized form through the ammonia injection pipe and is fully mixed with the flue gas containing high-valence nitrogen oxides.

[0048] The low-temperature SCR reactor has no external heating jacket or heating pipes on its outer wall, relying entirely on the 180-220℃ temperature inherent in the flue gas for the reaction. This temperature range perfectly matches the activity temperature range of the vanadium-titanium-based catalyst layer fixed within the reactor by a perforated mesh metal support. The vanadium-titanium-based catalyst layer has a honeycomb-like multi-layered porous structure, with pre-reserved flue gas flow channels between layers. The pore diameter is 4mm, suitable for the flow rate of waste incineration flue gas. The inner walls of the channels are loaded with vanadium-titanium active components. When the mixed flue gas flows through the vanadium-titanium-based catalyst layer, high-valence nitrogen oxides and ammonia undergo selective catalytic reduction under the action of the catalyst, achieving NO reduction. x The deep removal of this reaction process The removal efficiency reaches 98.5%, and there is no ammonia escape.

[0049] Operation process of flue gas waste heat recovery and closed-loop utilization unit

[0050] After denitrification, the flue gas exits from the flue gas outlet of the low-temperature SCR reactor and enters the flue gas flow chamber of the high-efficiency waste heat exchanger in the flue gas waste heat recovery and closed-loop utilization unit. The high-efficiency waste heat exchanger is a shell-and-tube flue gas-water heat exchange structure. Its flue gas flow chamber and feedwater flow chamber are arranged in a staggered manner. The inner wall of the flue gas flow chamber is provided with arrayed turbulence protrusions, which can turbulentize the flue gas and prolong the residence time of the flue gas in the chamber. The feedwater flow chamber is provided with spiral guide vanes, which can increase the heat exchange path of the feedwater. The combination of the two makes the heat exchanger heat exchange efficiency reach 92%.

[0051] The feedwater in the boiler feedwater system enters the feedwater flow chamber through the feedwater inlet of the high-efficiency waste heat heat exchanger. The medium-temperature waste heat of the flue gas after denitrification is transferred to the feedwater in the feedwater flow chamber through the heat exchanger tube wall, raising the feedwater temperature by 32°C. Temperature monitoring interfaces are welded to both the feedwater inlet and outlet of the feedwater flow chamber, and pressure monitoring interfaces are welded to both the flue gas inlet and outlet of the flue gas flow chamber. Operators can monitor the temperature changes of the feedwater and the pressure changes of the flue gas in real time through the sensors at the interfaces to ensure the stable operation of the heat exchanger. The feedwater that has absorbed waste heat is discharged through the feedwater outlet and flows back to the boiler system through the return water pipe. It works with the economizer and deaerator to preheat the boiler feedwater, realizing the closed-loop utilization of the flue gas waste heat.

[0052] The operation process of the subsequent purification and emission unit

[0053] After heat exchange by a high-efficiency waste heat exchanger, the flue gas, with its temperature reduced to 145℃, is discharged from the flue gas outlet and enters the dry reactor of the subsequent purification and emission unit through a stainless steel flue gas pipeline. The top of the dry reactor is equipped with a lime feed port, which is sealed to an external screw feeder. The lime is quantitatively added into the dry reactor through the screw feeder. The stirring and dispersing paddle inside the reactor chamber is located above the flue gas inlet, which fully disperses the lime, allowing the lime to fully mix and contact with the flue gas, thereby removing acidic gases and other impurities from the flue gas.

[0054] The flue gas purified by the dry reactor enters the bag filter. The bag filter is equipped with fiberglass filter bag assemblies, which intercept and filter the dust in the flue gas. The bag filter is also equipped with a cleaning jet pipe assembly, which is arranged parallel to the array direction of the fiberglass filter bag assemblies. The jet nozzles are directly facing the opening end of the filter bags, and compressed air is periodically sprayed into the filter bags to achieve efficient cleaning of the filter bags and ensure the filtration effect.

[0055] Both the dry reactor and the bag filter are equipped with a conical ash collection hopper at the bottom. The dust and ash generated during the flue gas purification process fall into the ash collection hopper. The ash discharge valve at the bottom of the ash collection hopper can be opened periodically to discharge the ash and ash for centralized treatment. The flue gas, after being deeply purified by the bag filter, is transported to the chimney through a stainless steel flue gas pipeline and discharged into the atmosphere after meeting the standards. All pollutant indicators of the emitted flue gas meet the current environmental emission requirements of the waste incineration industry.

[0056] The system of this invention is specifically designed for the treatment of flue gas from waste incineration. It achieves synergistic optimization of denitrification and waste heat recovery, ensuring efficient denitrification while realizing the resource utilization of flue gas waste heat. The system is stable in operation, has low energy consumption, and is easy to operate and maintain, making it suitable for industrial promotion and application in the waste incineration industry.

[0057] The beneficial effects of this invention are reflected in:

[0058] 1. Highly efficient and stable denitrification: Through low-temperature plasma pre-oxidation upgrading + low-temperature SCR deep reduction, it is adapted to waste incineration flue gas. Removal efficiency ≥98%, no ammonia escape, meeting stringent emission standards;

[0059] 2. Significantly reduced energy consumption: Utilizing the temperature of the flue gas itself, no external heating is required, resulting in a substantial reduction in denitrification energy consumption;

[0060] 3. High-efficiency waste heat recovery: heat exchange efficiency ≥90%, boiler feedwater temperature rise ≥30℃, and energy utilization rate improved;

[0061] 4. System Synergistic Efficiency: The integrated series design of denitrification and waste heat recovery is compact, efficient, and achieves the dual goals of purification and energy saving. It has a small footprint, simple process, and improves overall energy efficiency by more than 5%.

[0062] 5. Reduced operation and maintenance costs: Designed for the high dust, high humidity, and complex flue gas of waste incineration, the catalyst has a longer lifespan and more stable operation. The catalyst is resistant to poisoning and has an extended lifespan, reducing replacement and maintenance costs.

[0063] The above descriptions are merely embodiments of the present invention. Commonly known technical solutions or characteristics are not described in detail here. It should be noted that those skilled in the art can make various modifications and improvements without departing from the present invention, and these should also be considered within the scope of protection of the present invention. These modifications and improvements will not affect the effectiveness of the present invention or the practicality of the patent. The scope of protection claimed in this application should be determined by the content of its claims, and the specific embodiments described in the specification can be used to interpret the content of the claims.

Claims

1. A waste incineration flue gas low-temperature plasma coupling denitrification and waste heat utilization system, characterized in that, The system includes: Along the flow direction of waste incineration flue gas, a low-temperature plasma pre-oxidation unit, a low-temperature SCR deep denitrification unit, a flue gas waste heat recovery and closed-loop utilization unit, and a subsequent purification and emission unit are connected in series through seamlessly welded stainless steel flue gas pipelines. The low-temperature plasma pre-oxidation unit is equipped with a low-temperature plasma generator, which includes a high-voltage pulse electrical terminal, an internal electrode assembly, and a flue gas inlet and outlet. The flue gas inlet is sealed to a waste incineration flue gas pipeline with a temperature range of 180-220°C. The low-temperature SCR deep denitrification unit is equipped with a low-temperature SCR reactor. A vanadium-titanium-based catalyst layer is fixed inside the reactor by a metal support, and the activity temperature range of the vanadium-titanium-based catalyst layer is 180-220°C. The flue gas waste heat recovery and closed-loop utilization unit is equipped with a high-efficiency waste heat exchanger, which includes a flue gas inlet and outlet, a feedwater inlet, and a feedwater outlet. The feedwater inlet is sealed to the boiler feedwater system's outlet pipe, and the feedwater outlet is sealed to the boiler system's return water pipe. The flue gas inlet of the subsequent purification and emission unit is sealed to the flue gas outlet of the high-efficiency waste heat exchanger via a stainless steel flue gas pipeline.

2. The waste incineration flue gas low-temperature plasma coupling denitrification and waste heat utilization system according to claim 1, characterized in that: The internal electrode assembly of the low-temperature plasma generator has a needle-plate electrode structure. The high-voltage pulse terminal is electrically connected to an external high-voltage pulse power supply. The strong electric field region formed by the internal electrode assembly within the generator cavity completely covers the flue gas flow cross-section. When the waste incineration flue gas flows through the strong electric field region, the flue gas... , , and Gas molecules undergo ionization and dissociation reactions, generating •OH hydroxyl radicals. At least one highly reactive particle selected from ozone, O-oxygen atoms, and N-nitrogen atoms, said highly reactive particle oxidizes low-valence NO in flue gas to... , At least one high-valence nitrogen oxide.

3. The waste incineration flue gas low-temperature plasma coupling denitrification and waste heat utilization system according to claim 1, characterized in that: The low-temperature SCR reactor has a reducing agent inlet on the side wall of the cylinder. The reducing agent inlet is sealed and connected to an ammonia injection pipe. The ammonia injection pipe extends into the cavity of the low-temperature SCR reactor and its injection end is located at the front end of the flue gas flow of the vanadium-titanium-based catalyst layer. The outer wall of the low-temperature SCR reactor has no heat replenishment jacket or external heat replenishment pipeline.

4. The waste incineration flue gas low-temperature plasma coupling denitrification and waste heat utilization system according to claim 3, characterized in that: The vanadium-titanium-based catalyst layer has a honeycomb-like multi-layered porous structure, with pre-reserved flue gas guiding channels between the layers. The vanadium-titanium-based catalyst layer facilitates the flow of flue gas... The removal efficiency is ≥98%, the selective catalytic reduction reaction process in the low-temperature SCR reactor has no ammonia escape, and the pore size of the vanadium-titanium-based catalyst layer is adapted to the flow rate of the waste incineration flue gas.

5. The waste incineration flue gas low-temperature plasma coupling denitrification and waste heat utilization system according to claim 4, characterized in that: The vanadium-titanium-based catalyst layer has a pore size of 3-5 mm, and the inner wall of the pores is loaded with vanadium-titanium active components. The metal support is a hollow mesh structure and is welded and fixed to the inner wall of the cylinder of the low-temperature SCR reactor.

6. The waste incineration flue gas low-temperature plasma coupling denitrification and waste heat utilization system according to claim 1, characterized in that: The high-efficiency waste heat exchanger is a shell-and-tube flue gas-water heat exchange structure, which has a flue gas flow chamber and a feedwater flow chamber inside. The flue gas flow chamber is sealed and connected to the flue gas outlet of the low-temperature SCR reactor. The inlet of the feedwater flow chamber is sealed and connected to the outlet pipe of the boiler feedwater system. The outlet of the feedwater flow chamber is sealed and connected to the return water pipe of the boiler system. The medium-temperature waste heat of the flue gas after denitrification is transferred to the feedwater in the feedwater flow chamber through the high-efficiency waste heat exchanger. The feedwater that has absorbed the waste heat flows back to the boiler system through the return water pipe of the boiler system.

7. The waste incineration flue gas low-temperature plasma coupling denitrification and waste heat utilization system according to claim 6, characterized in that: The flue gas flow chamber and the feed water flow chamber of the high-efficiency waste heat exchanger are arranged in a staggered manner. The inner wall of the flue gas flow chamber is provided with arrayed turbulence protrusions, and the feed water flow chamber is provided with spiral guide vanes. Temperature monitoring interfaces are welded to both the feed water inlet and the feed water outlet of the feed water flow chamber, and pressure monitoring interfaces are welded to both the flue gas inlet and the flue gas outlet of the flue gas flow chamber.

8. The waste incineration flue gas low-temperature plasma coupling denitrification and waste heat utilization system according to claim 7, characterized in that: The subsequent purification and emission unit is provided with a dry reactor and a bag filter in sequence along the flue gas flow direction. The dry reactor is sealed to the flue gas outlet of the high-efficiency waste heat exchanger through the stainless steel flue gas pipeline. The top of the dry reactor is provided with a lime feeding port, and the cavity is provided with a stirring and dispersing paddle. The cavity of the bag filter is provided with a fiberglass filter bag assembly and a dust removal spray pipe assembly. The temperature of the flue gas after heat exchange in the high-efficiency waste heat exchanger when it enters the dry reactor is 145°C.

9. A waste incineration flue gas low-temperature plasma coupling denitrification and waste heat utilization system according to claim 8, characterized in that: The lime feed port of the dry reactor is sealed to an external screw feeder. The stirring and dispersing paddle is located above the flue gas inlet of the dry reactor. The cleaning jet pipe assembly of the bag filter is arranged parallel to the array direction of the fiberglass filter bag assembly, and the jet nozzle is directly opposite the opening end of the filter bag. The flue gas outlet of the bag filter is sealed to the exhaust chimney through a stainless steel flue gas pipeline. Both the dry reactor and the bag filter are equipped with a conical ash collection hopper at the bottom, and an ash discharge valve is installed at the bottom of the ash collection hopper.

10. The waste incineration flue gas low-temperature plasma coupling denitrification and waste heat utilization system according to claim 1, characterized in that: The system is an integrated skid-mounted structure. The equipment bodies of the low-temperature plasma pre-oxidation unit, the low-temperature SCR deep denitrification unit, the flue gas waste heat recovery and closed-loop utilization unit, and the subsequent purification and emission unit are all fixedly installed on the same steel structure base. The control valves and instrument interfaces of each unit are integrated into the operation panel on one side of the steel structure base.

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