Environment-friendly flue gas waste heat boiler

Abstract

According to the environment-friendly flue gas waste heat boiler, an L-shaped flue gas pipeline is adopted, heat exchange and denitration equipment is arranged in order according to the flue gas temperature gradient, high-temperature flue gas denitration pretreatment and high-grade heat recovery are completed through a horizontal section, medium-low temperature waste heat deep utilization is achieved through a vertical section, waste heat resources are excavated to the maximum extent, and the heat efficiency of the boiler is improved. The ammonia spraying grid and the SCR catalyst module are integrated, the reaction temperature is accurately controlled in cooperation with the temperature regulator, it is ensured that ammonia water and flue gas are fully mixed, the denitration reaction is efficiently conducted, and the requirement for ultralow emission of nitric oxide is met. In the steam-water system, a steam drum, a water feeding pump and a deaerator are cooperatively operated, the deaerator removes dissolved oxygen in condensed water to guarantee the water supply quality, the water feeding pump conveys water to a coal economizer in a pressurized mode, and the steam drum separates a steam-water mixture; meanwhile, the water spraying desuperheater is matched with the thermolator, temperature control is accurate, different load working conditions are adapted, and stable output of steam is ensured.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of environment-friendly flue gas waste heat boiler, in particular to an environment-friendly flue gas waste heat boiler. BACKGROUND

[0002] In the industrial field, flue gas waste heat boiler as a key equipment for recycling heat energy in high-temperature flue gas and realizing energy secondary utilization is widely used in metallurgy, mining, petrochemical, papermaking and other industries. However, the current domestic flue gas waste heat boilers in production are limited by technical design and functional positioning, and generally have the problems of simple structure and prominent performance short board, which are difficult to adapt to the dual demands of energy efficient utilization and environmental protection emission in the industry, and the specific status is as follows:

[0003] From the perspective of waste heat recovery efficiency, the existing flue gas waste heat boiler is not optimized in design for temperature cascade utilization due to the single structure form, resulting in insufficient exploitation of waste heat resources. The exhaust gas temperature is generally maintained above 180℃, and a large amount of heat energy carried by low-temperature section flue gas is directly discharged without being recovered, causing serious energy waste, reducing the overall energy efficiency of the boiler, and not meeting the development trend of energy saving and consumption reduction in the industrial field.

[0004] In terms of running stability and working condition adaptability, the temperature adjustment form of the existing boiler is extremely single, and most of them only rely on water spray desuperheater for temperature control. This single temperature adjustment method cannot cope with complex variable load conditions: when the boiler is running at different load rates of 30% to 100%, the water spray desuperheater is difficult to accurately match the dynamic changes of flue gas temperature and steam demand, not only increasing the difficulty of production control significantly, but also causing problems such as temperature regulation lag and large fluctuation range, which seriously affects the quality stability of the boiler output steam, and further restricts the running efficiency of downstream energy-using equipment (such as steam turbine unit).

[0005] More importantly, the existing flue gas waste heat boiler generally lacks supporting denitration treatment facilities and cannot effectively treat nitrogen oxides in flue gas. With the continuous upgrading of national environmental protection standards, the current ultra-low emission standard for nitrogen oxides has clearly required that the emission concentration be ≤50mg / m 3 However, some flue gas waste heat boilers are not associated with any denitration equipment and have no denitration treatment function, and the emission of nitrogen oxides directly exceeds the standard, so such equipment has faced the risk of being eliminated by the industry under the background of tightening environmental protection policies.

[0006] In summary, the performance deficiency of the existing flue gas waste heat boiler in the three core demands of waste heat recovery, variable load temperature adjustment and denitration treatment has become a key bottleneck restricting the green and low-carbon development in the industrial field, and it is urgent to develop a new type of flue gas waste heat boiler with efficient waste heat recovery, precise temperature adjustment and denitration function. SUMMARY

[0007] In order to overcome the above-mentioned defects of the prior art, the present application provides an environmentally friendly flue gas waste heat boiler, which aims to solve the performance deficiency of the existing flue gas waste heat boiler in the three core requirements of waste heat recovery, variable load temperature adjustment and denitration treatment.

[0008] The technical scheme adopted by the present application to solve its technical problems is: an environmentally friendly flue gas waste heat boiler, comprising a flue gas pipeline, a heat exchange device and a denitration device, the heat exchange device comprising a superheater, a temperature regulator, an evaporator, a coal economizer and a condensate heater, the denitration device comprising an ammonia injection grid and an SCR catalyst module, the ammonia injection grid, the superheater, the temperature regulator, the SCR catalyst module, the evaporator, the coal economizer and the condensate heater being arranged in the flue gas pipeline in sequence along the flue gas flow direction.

[0009] As a further improvement of the present application: a sound wave soot blower is arranged in the flue gas pipeline, the sound wave soot blower being located between the SCR catalyst module and the temperature regulator, and the sound wave soot blower being used to remove the particles adhering to the surface of the SCR catalyst module. By arranging the sound wave soot blower between the SCR catalyst module and the temperature regulator, the particles adhering to the surface of the SCR catalyst module can be accurately removed, avoiding the accumulation of particles to block the active sites of the catalyst, maintaining the catalytic efficiency of the catalyst and ensuring the stability of the denitration effect.

[0010] As a further improvement of the present application: the flue gas pipeline is in L-shaped structure. By arranging the flue gas pipeline in L-shaped structure, the L-shaped structure can optimize the flue gas flow path, facilitating the reasonable arrangement of the superheater, the temperature regulator, the condensate heater and other devices in the flue gas pipeline according to the flue gas temperature gradient, allowing the high-temperature to low-temperature flue gas to act on the corresponding heat exchange devices in sequence, better adapting to the step-by-step heat exchange demand and improving the waste heat recovery efficiency.

[0011] As a further improvement of the present application: the flue gas pipeline comprises a horizontal flue and a vertical flue, the inlet end of the horizontal flue being communicated with high-temperature flue gas, and the outlet end of the horizontal flue being connected with the lower end of the vertical flue. By communicating the high-temperature flue gas with the inlet end of the horizontal flue, the high-temperature flue gas can be smoothly introduced into the pipeline.

[0012] As a further improvement of the present application: the ammonia injection grid, the superheater, the temperature regulator and the SCR catalyst module are arranged in the horizontal flue in sequence along the flue gas flow direction. By arranging the ammonia injection grid, the superheater, the temperature regulator and the SCR catalyst module in the horizontal flue in sequence along the flue gas flow direction, the high-temperature flue gas is first mixed with ammonia water in the ammonia injection grid, then releases heat in the superheater, and then is precisely temperature-controlled in the temperature regulator, which can stably adjust the flue gas temperature to the appropriate reaction interval of the SCR catalyst module, ensuring the denitration efficiency. By arranging the ammonia injection grid and the SCR catalyst module on the same horizontal line and reserving sufficient length of ammonia water and high-temperature flue gas mixing space between them, the uniform mixing of ammonia water can be maximized, improving the denitration efficiency.

[0013] As a further improvement of the present invention: the evaporator, economizer, and condensate heater are sequentially arranged inside the vertical flue along the flue gas flow direction. By sequentially arranging the evaporator, economizer, and condensate heater inside the vertical flue along the flue gas flow direction, it can adapt to the characteristic of the flue gas temperature gradually decreasing. This allows the medium-temperature flue gas to release heat first through the evaporator and economizer, and the low-temperature flue gas to undergo deep heat exchange through the condensate heater, realizing the cascade utilization of flue gas waste heat, minimizing heat energy waste, and improving boiler thermal efficiency.

[0014] As a further improvement of the present invention, it also includes a deaerator, the input end of which is connected to the output end of the condensate heater via a pipeline, and the deaerator is connected to the economizer via a pipeline. The condensate heater is located at the end of the flue gas pipeline, and is used to receive the condensate after the turbine has done its work, and to preheat the condensate using the low-temperature flue gas from the boiler; the deaerator is used to remove most of the dissolved oxygen from the condensate; the economizer is used to heat the water pumped by the feedwater pump using the relatively low-temperature flue gas at the tail end of the boiler.

[0015] As a further improvement of the present invention, a feedwater pump is also included. The feedwater pump is installed on the pipeline between the deaerator and the economizer. The input end of the feedwater pump is connected to the output end of the deaerator via a pipeline, and the output end of the feedwater pump is connected to the input end of the economizer via a pipeline. The feedwater pump is used to pressurize the deaerated water and send it into the economizer. By installing the feedwater pump on the pipeline between the deaerator and the economizer, the deaerated water can be pressurized and sent into the economizer. When the pressurized water exchanges heat with the flue gas in the economizer, the flow rate and contact effect are better, which can improve the heat exchange efficiency. At the same time, it adapts to the water pressure requirements of the subsequent steam-water circulation, providing power support for the smooth operation of the overall boiler steam-water system.

[0016] As a further improvement of the present invention, it also includes a steam drum, the input end of which is connected to the output end of the economizer via a pipeline, and the output end of the steam drum is connected to the superheater, evaporator, and thermostat via pipelines. The steam drum input end, connected to the economizer output end, can receive the steam-water mixture heated by the economizer. Through its internal steam-water separation function, it accurately separates saturated steam from unsaturated liquid water, providing qualified working fluid for subsequent equipment and preventing liquid water from entering the superheater and affecting steam quality. Furthermore, the steam drum output end, connected to the superheater, evaporator, and thermostat, allows the separated saturated steam to be sent to the superheater for further heating, while the unsaturated liquid water is transported to the evaporator and thermostat for circulating heating, forming a complete and efficient steam-water circulation process, improving thermal energy utilization, and ensuring a stable supply of working fluid to each heat exchange device, reducing system operation fluctuations.

[0017] As a further improvement of the present invention, it also includes a water spray desuperheater, which is installed on the outlet steam pipe of the superheater and is used to cool the superheated steam output by the superheater to ensure that the steam temperature does not exceed the limit.

[0018] Compared with the prior art, the beneficial effects of the present invention are:

[0019] 1. This invention achieves tiered utilization of flue gas heat by arranging the superheater, thermostat, evaporator, economizer, and condensate heater in an orderly manner according to the flue gas flow direction. High-temperature flue gas first releases high-grade heat through the superheater and thermostat, then sequentially passes through the evaporator, economizer, and condensate heater to transfer medium- and low-temperature heat. In particular, the condensate heater can deeply recover waste heat in the low-temperature section, minimizing heat waste and improving waste heat recovery efficiency, thereby enhancing the overall thermal efficiency of the boiler.

[0020] 2. By setting a thermostat, the present invention can flexibly adjust the heat absorption according to the changes in flue gas temperature, and make timely adjustments to the heat absorption under different load rates from 30% to 100%, adapting to the temperature requirements under different load conditions, avoiding the limitations of a single temperature adjustment method, ensuring the stability of the operating environment of subsequent equipment, and improving the overall reliability of boiler operation.

[0021] 3. This invention integrates the ammonia injection grid and the SCR catalyst module into the flue gas duct, with the ammonia injection grid located at the front end. This allows the ammonia water and flue gas to mix thoroughly during flow, creating favorable conditions for the subsequent efficient denitrification of the SCR catalyst module and helping to achieve the standard for nitrogen oxide emissions from the flue gas. At the same time, the integrated layout of each device simplifies the system structure and reduces space occupation and connection costs. Attached Figure Description

[0022] Figure 1 This is a process flow diagram of the present invention.

[0023] Reference numerals: 1. Condensate heater; 2. Economizer; 3. Evaporator; 4. SCR catalyst module; 5. Acoustic soot blower; 6. Temperature controller; 7. Superheater; 8. Water spray desuperheater; 9. Ammonia spray grid; 10. Feedwater pump; 11. Deaerator; 12. Steam drum. Detailed Implementation

[0024] To make the objectives, technical solutions, and advantages of the present invention clearer, the technical solutions of the present invention will be clearly and completely described below in conjunction with specific embodiments and corresponding drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them. 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. It should be noted that the terms "comprising" and "having," and any variations thereof, are intended to cover non-exclusive inclusion. For example, a process, method, system, product, or device that includes a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to these processes, methods, products, or devices.

[0025] Please see Figure 1 An environmentally friendly flue gas waste heat boiler includes a flue gas duct, heat exchange equipment, and denitrification equipment. The heat exchange equipment includes a superheater 7, a thermostat 6, an evaporator 3, an economizer 2, and a condensate heater 1. The denitrification equipment includes an ammonia injection grid 9 and an SCR catalyst module 4. The ammonia injection grid 9, superheater 7, thermostat 6, SCR catalyst module 4, evaporator 3, economizer 2, and condensate heater 1 are sequentially arranged inside the flue gas duct along the flue gas flow direction.

[0026] By arranging the superheater 7, thermostat 6, evaporator 3, economizer 2, and condensate heater 1 in an orderly manner according to the flue gas flow direction, the cascade utilization of flue gas heat can be achieved. High-temperature flue gas first releases high-grade heat through superheater 7 and thermostat 6, and then sequentially transfers medium- and low-temperature heat through evaporator 3, economizer 2, and condensate heater 1. In particular, condensate heater 1 can deeply recover waste heat in the low-temperature section, minimizing heat energy waste, improving waste heat recovery efficiency, and thus improving the overall thermal efficiency of the boiler.

[0027] By setting thermostat 6, the heat absorption can be flexibly adjusted according to the changes in flue gas temperature. The heat absorption can be adjusted in a timely manner under different load rates from 30% to 100%, adapting to the temperature requirements under different load conditions. This avoids the limitations of a single temperature adjustment method, ensures the stability of the operating environment of subsequent equipment, and improves the overall reliability of boiler operation.

[0028] By integrating the ammonia injection grille 9 with the SCR catalyst module 4 into the flue gas duct, with the ammonia injection grille 9 located at the front end, the ammonia water and flue gas can be fully mixed during the flow, creating favorable conditions for the subsequent efficient denitrification of the SCR catalyst module 4, helping the flue gas nitrogen oxide emissions meet the standards. At the same time, the integrated layout of each device simplifies the system structure and reduces space occupation and connection costs.

[0029] In some embodiments, an acoustic soot blower 5 is provided inside the flue gas duct, the acoustic soot blower 5 is located between the SCR catalyst module 4 and the temperature controller 6, and the acoustic soot blower 5 is used to remove particulate matter adhering to the surface of the SCR catalyst module 4.

[0030] By strategically placing an acoustic soot blower 5 between the SCR catalyst module 4 and the temperature controller 6, particulate matter adhering to the surface of the SCR catalyst module 4 can be precisely removed, preventing particulate matter accumulation from obscuring the active sites of the catalyst, maintaining the catalyst's catalytic efficiency, and ensuring stable denitrification performance. Secondly, cleaning can be achieved without disassembling the equipment, reducing interference with the normal operation of the boiler and lowering the frequency and cost of downtime maintenance. At the same time, the acoustic cleaning method will not cause physical damage to the SCR catalyst module 4, extending its service life and ensuring the long-term reliable operation of the denitrification system, thus contributing to the stable compliance of flue gas nitrogen oxide emissions.

[0031] In some embodiments, the flue gas duct has an L-shaped structure.

[0032] By setting the flue gas duct to an L-shaped structure, the flue gas flow path can be optimized, and it is convenient to arrange equipment such as superheater 7, thermostat 6, and condensate heater 1 in the flue gas duct according to the flue gas temperature gradient. This allows the high-temperature to low-temperature flue gas to interact with the corresponding heat exchange equipment in sequence, which is more suitable for the cascade heat exchange requirements and improves the waste heat recovery efficiency.

[0033] In some embodiments, the flue gas duct includes a horizontal flue and a vertical flue, the inlet end of the horizontal flue being connected to high-temperature flue gas, and the outlet end of the horizontal flue being connected to the lower end of the vertical flue.

[0034] By connecting the high-temperature flue gas at the horizontal flue inlet, the high-temperature flue gas can enter the pipeline smoothly. At the same time, the horizontal layout facilitates the installation of front-end equipment such as ammonia injection grille 9 and superheater 7 within the flue, making equipment fixation and maintenance convenient. Secondly, the horizontal flue outlet connects to the lower end of the vertical flue, forming a reasonable flue gas turning path, which is suitable for the staged heat exchange requirements of the L-shaped structure. In the horizontal section, the high-temperature flue gas can complete key heat exchange and denitrification pretreatment, and then the flue gas can flow naturally to the vertical section to fully cooperate with subsequent equipment such as evaporator 3 and economizer 2, improving waste heat recovery and flue gas treatment efficiency. Moreover, this structure can reduce flue gas stagnation dead zones and ensure smooth overall flow.

[0035] In some embodiments, the ammonia injection grille 9, superheater 7, thermostat 6, and SCR catalyst module 4 are sequentially arranged inside the horizontal flue along the flue gas flow direction.

[0036] By incorporating an ammonia injection grid 9 and an SCR catalyst module 4, both arranged on the same horizontal line with a sufficiently long mixing space between them for ammonia water and high-temperature flue gas, the uniform mixing of ammonia water can be ensured to the greatest extent, thereby improving the denitrification efficiency.

[0037] Within the horizontal flue, an ammonia injection grille 9, a superheater 7, a temperature controller 6, and an SCR catalyst module 4 are sequentially arranged along the flue gas flow direction. High-temperature flue gas first undergoes thorough mixing with ammonia water through the ammonia injection grille 9, then flows through the superheater 7 to release heat, and finally is precisely temperature-controlled by the temperature controller 6. This ensures the flue gas temperature is stably adjusted to the appropriate reaction range of the SCR catalyst module 4, guaranteeing denitrification efficiency. Furthermore, the horizontal layout allows for smooth flue gas flow within the flue, reducing the interference of flow velocity fluctuations on mixing and catalytic reactions, ensuring orderly coordination between waste heat recovery and denitrification processes, and improving the overall operational stability of the system.

[0038] In some embodiments, the evaporator 3, economizer 2, and condensate heater 1 are sequentially arranged inside the vertical flue along the flue gas flow direction.

[0039] By sequentially arranging the evaporator 3, economizer 2, and condensate heater 1 along the flue gas flow direction within the vertical flue, the design adapts to the gradually decreasing flue gas temperature. This allows medium-temperature flue gas to release heat first through the evaporator 3 and economizer 2, while the low-temperature flue gas undergoes further heat exchange through the condensate heater 1. This multi-stage utilization of waste heat minimizes heat waste and improves boiler thermal efficiency. Furthermore, the vertical layout conforms to the natural flow trend of flue gas, reducing flow resistance, avoiding dead zones, and ensuring smooth passage of flue gas through all heat exchange devices.

[0040] In some embodiments, a deaerator 11 is also included, the input end of which is connected to the output end of the condensate heater 1 via a pipeline, and the deaerator 11 is connected to the economizer 2 via a pipeline.

[0041] The condensate heater 1 is located at the end of the flue gas duct. The condensate heater 1 is used to receive the condensate after the steam turbine has done its work and to preheat the condensate using the flue gas in the low-temperature section of the boiler. The deaerator 11 is used to remove most of the dissolved oxygen from the condensate. The economizer 2 is used to heat the water pumped by the feedwater pump 10 using the relatively low-temperature flue gas at the tail of the boiler.

[0042] By connecting the input end of the deaerator 11 to the output end of the condensate heater 1, the condensate heated by waste heat can be further deoxygenated, removing most of the dissolved oxygen in the water and ensuring that the boiler feedwater quality meets the standards. Secondly, the deaerator 11 is connected to the economizer 2 through a pipeline, so that the deoxygenated water is directly transported to the economizer 2, forming a continuous process of "condensate heating - deaeration - economizer 2 reheating", reducing intermediate transportation losses, improving the overall heat exchange efficiency of the steam-water system, and ensuring the stable operation of subsequent steam-water circulation.

[0043] In some embodiments, a feedwater pump 10 is also included. The feedwater pump 10 is installed on the pipeline between the deaerator 11 and the economizer 2. The input end of the feedwater pump 10 is connected to the output end of the deaerator 11 through a pipeline, and the output end of the feedwater pump 10 is connected to the input end of the economizer 2 through a pipeline. The feedwater pump 10 is used to pressurize the deaerated water and send it into the economizer 2.

[0044] The feedwater pump 10, located in the pipeline between the deaerator 11 and the economizer 2, pressurizes the deaerated water before sending it into the economizer 2. This compensates for pressure losses during pipeline transport, ensuring efficient water flow into the economizer 2 under pressure and preventing flow obstruction due to insufficient pressure. This guarantees the stable operation of the heat exchange process in the economizer 2. Furthermore, the pressurized water exhibits better flow velocity and contact effect when exchanging heat with the flue gas in the economizer 2, improving heat exchange efficiency. It also meets the subsequent steam-water circulation's water pressure requirements, providing power support for the smooth operation of the overall boiler steam-water system and reducing the risk of system failures caused by water pressure issues.

[0045] In some embodiments, a steam drum 12 is also included, the input end of which is connected to the output end of the economizer 2 via a pipeline, and the output end of the steam drum 12 is connected to the superheater 7, the evaporator 3 and the thermostat 6 via pipelines respectively.

[0046] Economizer 2 is used to heat the water delivered by feedwater pump 10 using the relatively low-temperature flue gas at the tail of the boiler, and then send the heated water into steam drum 12; steam drum 12 is used to separate the steam-water mixture output from economizer 2, send saturated steam into superheater 7, and send unsaturated liquid water into evaporator 3 and thermostat 6 for circulating heating; the evaporator 3 is used to heat the unsaturated liquid water output from steam drum 12 using the higher-temperature flue gas from the boiler.

[0047] The input end of the steam drum 12 is connected to the output end of the economizer 2, and can receive the steam-water mixture heated by the economizer 2. Through the internal steam-water separation function, the saturated steam and unsaturated liquid water are accurately separated to provide qualified working fluid for subsequent equipment and prevent liquid water from entering the superheater 7 and affecting the steam quality. Secondly, the output end of the steam drum 12 is connected to the superheater 7, the evaporator 3 and the thermostat 6 respectively. It can send the separated saturated steam to the superheater 7 for further heating, while the unsaturated liquid water is sent to the evaporator 3 and the thermostat 6 for circulation heating, forming a complete and efficient steam-water circulation process, improving the thermal energy utilization rate, while ensuring a stable supply of working fluid to each heat exchanger and reducing system operation fluctuations.

[0048] In some embodiments, a water spray desuperheater 8 is also included. The water spray desuperheater 8 is located on the outlet steam pipe of the superheater 7 and is used to cool the superheated steam output by the superheater 7 to ensure that the steam temperature does not exceed the limit.

[0049] By installing the water spray desuperheater 8 at the outlet steam pipe of the superheater 7, the superheated steam output from the superheater 7 can be directly cooled, precisely controlling the steam temperature to prevent it from exceeding limits and avoiding damage to downstream equipment such as the turbine unit due to steam overheating, thus ensuring the safe and stable operation of energy-consuming equipment. Secondly, by adjusting the water spray volume in real time, it can flexibly adapt to steam temperature fluctuations under varying boiler load conditions, ensuring that the output steam always meets the temperature standards required by the process, improving steam quality stability, and preventing system shutdowns or malfunctions due to steam overheating, reducing the risk of production interruptions and ensuring the overall operating efficiency of the boiler.

[0050] The flue gas waste heat boiler of this invention adopts an L-shaped structure design, which comprehensively considers the cascade utilization of flue gas temperature and is equipped with a condensate heater. The flue gas in the low-temperature section of the boiler is used to preheat the condensate of the steam turbine, reducing the exhaust gas temperature from the conventional above 180°C to below 140°C, which greatly taps the utilization rate of waste heat resources and improves boiler efficiency.

[0051] The flue gas waste heat boiler of the present invention is based on an L-shaped flue gas duct and is equipped with an adjustable thermostat in the high-temperature section of the flue gas. It can adjust the heat absorption in a timely manner according to the temperature change of the flue gas at different load rates from 30% to 100%. This not only meets the suitable reaction temperature range of 280℃ to 420℃ for the next process SCR catalyst module, but also assists the water spray desuperheater in completing the dynamic adjustment of the boiler outlet steam temperature.

[0052] The boiler of this invention is equipped with an ammonia injection grid and an SCR catalyst module, both arranged on the same horizontal line, and has a sufficiently long mixing space for ammonia water and high-temperature flue gas, which can ensure the uniform mixing of ammonia water to the greatest extent and improve the denitrification efficiency.

[0053] Working principle of the invention:

[0054] I. Description of Boiler Components:

[0055] (1) Condensate heater: Its main function is to use the flue gas in the low-temperature section of the boiler to preheat the condensate of the steam turbine before sending it to the deaerator. The purpose is to reduce the flue gas temperature from the conventional 180℃ or above to below 140℃, which can greatly improve the boiler efficiency.

[0056] (2) Economizer: Its main function is to use the relatively low-temperature flue gas at the tail of the boiler to heat the water from the feed water pump and then send it into the steam drum for steam-water separation.

[0057] (3) Evaporator, whose main function is to heat the boiler water in the steam drum. Its function is equivalent to the water-cooled wall of a conventional boiler, which uses the high-temperature flue gas in the furnace to heat the boiler water.

[0058] (4) The SCR catalyst module mainly provides a catalytic environment to accelerate the reaction of ammonia and nitrogen oxides to generate nitrogen and water, ensuring that the flue gas emitted by the boiler meets the ultra-low emission standards.

[0059] (5) Acoustic soot blower, whose main function is to periodically clean the particles adhering to the catalyst surface of the SCR catalyst module by impact, so as to ensure that the catalyst surface is kept clean.

[0060] (6) The thermostat's main function is to adjust the heat absorption in a timely manner according to the temperature change of the flue gas under different load rates of 30% to 100% of the boiler. It can not only meet the reaction temperature range of 280℃ to 420℃ of the next process SCR catalyst module, but also assist the water spray desuperheater in completing the dynamic adjustment of the boiler outlet steam temperature, so as to achieve the purpose of adjusting the boiler heat load distribution.

[0061] (7) The superheater's main function is to further heat the saturated steam from the steam drum into superheated steam to meet the superheat requirements and ensure that the quality of the superheated steam is up to standard.

[0062] (8) Water spray desuperheater, whose main function is to spray water to cool down the overheated steam when it exceeds the maximum temperature limit, so as to ensure that the overheated steam does not exceed the temperature limit.

[0063] (9) Ammonia spraying grid, whose main function is to control the ammonia water to be sprayed into a plane to form multi-point spray, so as to ensure uniformity at the interface.

[0064] (10) Feed pump, whose main function is to provide the power source for the boiler steam-water system and pressurize the deoxygenated water before sending it to the economizer.

[0065] (11) Deaerator, whose main function is to heat the condensate to 103-104℃ and remove most of the oxygen in the condensate to ensure that the boiler feedwater quality meets the standards.

[0066] (12) Steam drum, whose main function is to separate the heated boiler water into steam and water, send saturated steam into the superheater, and send unsaturated liquid water into the evaporator and thermostat for circulating heating.

[0067] II. Boiler Steam-Water System Description:

[0068] 1. The boiler steam-water system mainly consists of condensate, condensate heater, deaerator, feedwater pump, economizer, steam drum, thermostat, superheater, spray desuperheater, etc.

[0069] 2. Condensate from the turbine after it has completed its work is pressurized by a pump set and sent to a condensate heater near the boiler exhaust outlet for initial heating. It is then sent to a deaerator for further heating to remove most of the dissolved oxygen. The deaerated condensate is then pressurized by a feedwater pump and sent to the economizer for initial heating. The resulting steam-water mixture enters the steam drum for steam-water separation. The saturated steam separated from the steam drum enters the superheater for heating to increase superheat. After passing through a desuperheater, the superheated steam meets the temperature control requirements and is sent to the turbine unit for expansion and work. The unsaturated liquid water separated from the steam drum is circulated and heated through the evaporator and thermostat before returning to the steam drum for repeated steam-water separation.

[0070] III. Boiler Flue Gas System Description:

[0071] 1. The boiler flue gas system mainly consists of flue gas ducts, boiler furnace walls, the outer surfaces of each heat exchanger, and the boiler chimney.

[0072] 2. High-temperature flue gas from each gas turbine generator unit is collected through flue gas ducts and first enters the ammonia injection grid in the boiler's flue gas duct. The high-temperature flue gas evaporates the ammonia water injected into the boiler into water vapor and ammonia gas. The mixed flue gas formed by the flue gas, ammonia gas, and water vapor first flows through the superheater to heat the steam inside. The mixed flue gas then flows through the thermostat to exchange heat with the boiler water inside. The mixed flue gas then flows through the SCR catalyst module, where nitrogen oxides in the flue gas react with ammonia gas to generate nitrogen gas under the action of the catalyst. The mixed flue gas then flows through the evaporator to exchange heat with the boiler water. The mixed flue gas then flows through the economizer to exchange heat with the boiler feedwater. The mixed flue gas then flows through the condensate heater to exchange heat with the condensate. The qualified mixed flue gas is finally discharged through the flue gas flushing.

[0073] The main functions of this invention are:

[0074] This invention employs an L-shaped flue gas duct, with heat exchange and denitrification equipment arranged in an orderly manner according to the flue gas temperature gradient. The horizontal section completes high-temperature flue gas denitrification pretreatment and high-grade heat recovery, while the vertical section achieves deep utilization of medium- and low-temperature waste heat. In particular, the condensate heater reduces the exhaust temperature to below 140℃, maximizing the exploitation of waste heat resources and improving boiler thermal efficiency. Secondly, by integrating an ammonia injection grid and an SCR catalyst module, along with a thermostat to precisely control the reaction temperature, it ensures thorough mixing of ammonia water and flue gas, and efficient denitrification reaction, meeting the requirements for ultra-low nitrogen oxide emissions. In the steam-water system, the steam drum, feedwater pump, and deaerator operate collaboratively as the core, constructing a complete cycle process of "condensate heating - deaeration - pressurization and transportation - heat exchange - steam-water separation - steam temperature regulation." The deaerator removes dissolved oxygen from the condensate to ensure feedwater quality, the feedwater pump pressurizes and delivers water to the economizer, and the steam drum separates the steam-water mixture. Meanwhile, the water spray desuperheater works in conjunction with the thermostat to precisely control the temperature, adapting to variable load conditions of 30% to 100% and ensuring stable steam output.

[0075] In the several embodiments provided in this application, it should be understood that the disclosed technical content can be implemented in other ways. The device embodiments described above are merely illustrative; for example, the division of units can be a logical functional division, and in actual implementation, there may be other division methods. For example, multiple units or components may be combined or integrated into another system, or some features may be ignored or not executed.

[0076] The units described as separate components may or may not be physically separate. Similarly, the components of the control device may or may not be physical units; they may be located in one place or distributed across multiple units. Some or all of the units can be selected to achieve the purpose of this embodiment, depending on actual needs.

[0077] The above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention, and they should all be covered within the scope of the claims and specification of the present invention.

Claims

1. An environmentally friendly flue gas waste heat boiler, characterized in that: The system includes flue gas ducts, heat exchange equipment, and denitrification equipment. The heat exchange equipment includes a superheater, a thermostat, an evaporator, an economizer, and a condensate heater. The denitrification equipment includes an ammonia injection grid and an SCR catalyst module. The ammonia injection grid, superheater, thermostat, SCR catalyst module, evaporator, economizer, and condensate heater are sequentially arranged inside the flue gas duct along the flue gas flow direction.

2. The environmentally friendly flue gas waste heat boiler according to claim 1, characterized in that: An acoustic soot blower is installed inside the flue gas duct. The acoustic soot blower is located between the SCR catalyst module and the temperature controller. The acoustic soot blower is used to remove particulate matter adhering to the surface of the SCR catalyst module.

3. The environmentally friendly flue gas waste heat boiler according to claim 1, characterized in that: The flue gas duct has an L-shaped structure.

4. The environmentally friendly flue gas waste heat boiler according to claim 3, characterized in that: The flue gas duct includes a horizontal flue and a vertical flue. The inlet end of the horizontal flue is connected to high-temperature flue gas, and the outlet end of the horizontal flue is connected to the lower end of the vertical flue.

5. The environmentally friendly flue gas waste heat boiler according to claim 4, characterized in that: The ammonia injection grid, superheater, temperature controller, and SCR catalyst module are sequentially arranged inside the horizontal flue along the flue gas flow direction.

6. The environmentally friendly flue gas waste heat boiler according to claim 5, characterized in that: The evaporator, economizer, and condensate heater are sequentially arranged inside the vertical flue along the flue gas flow direction.

7. The environmentally friendly flue gas waste heat boiler according to claim 6, characterized in that: It also includes a deaerator, the input end of which is connected to the output end of the condensate heater via a pipeline, and the deaerator is connected to the economizer via a pipeline.

8. The environmentally friendly flue gas waste heat boiler according to claim 7, characterized in that: It also includes a feedwater pump, which is installed on the pipeline between the deaerator and the economizer. The input end of the feedwater pump is connected to the output end of the deaerator through a pipeline, and the output end of the feedwater pump is connected to the input end of the economizer through a pipeline.

9. An environmentally friendly flue gas waste heat boiler according to claim 8, characterized in that: It also includes a steam drum, the input end of which is connected to the output end of the economizer via a pipeline, and the output end of which is connected to the superheater, evaporator and thermostat via pipelines.

10. An environmentally friendly flue gas waste heat boiler according to claim 1, characterized in that: It also includes a water spray desuperheater, which is installed on the outlet steam pipe of the superheater.

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