Efficient pulverized coal fired boiler low-temperature economizer

Abstract

The invention provides an efficient pulverized coal fired boiler low-temperature economizer, and relates to the field of economizers. The smoke inlet pipeline structure is connected to the smoke inlet side of the wide-runner plate heat exchanger. The smoke exhaust pipeline structure is connected to the smoke exhaust side of the wide-runner plate heat exchanger. The shape, the length and the installation mode of the wear-resistant part are selected on the windward side of the wide-runner plate heat exchanger according to the shape of an inlet flue, the smoke flow speed, particle size distribution of particulate matter in ash, the fly ash hardness and the incident angle, and the purpose is to consume kinetic energy of coarse particles with the overlarge incident angle and modify the running direction of the coarse particles through collision so as to relieve abrasion to subsequent heat exchange plates. A wide-runner corrugated heat exchange plate is arranged in the wide-runner plate heat exchanger; the wide-runner corrugated heat exchange plate is made of a titanium plate material; when the plate sheets of the wide-runner corrugated heat exchange plate are designed, the welding ring pitch and the bulging height are set, and it is guaranteed that orderly scouring of smoke to the plate sheets is not in a large-abrasion angle area. The anti-blocking, anti-corrosion and anti-abrasion effects are achieved.

Description

Technical Field

[0001] This invention relates to the field of economizer technology, specifically to a low-temperature economizer for high-efficiency pulverized coal boilers. Background Technology

[0002] Boiler flue gas waste heat recovery technology is a core means of achieving energy conservation, emission reduction, and efficient energy utilization in the industrial sector. It involves specifically capturing the sensible and latent heat in flue gas and converting it into usable energy. In the field of medium- and high-temperature flue gas recovery, economizers and air preheaters are the fundamental and most widely used technologies and equipment. Economizers are typically installed in the tail flue of the boiler, transferring the waste heat from the exhaust gas to the boiler feedwater through a serpentine tube bundle.

[0003] Challenges in applying serpentine tube bundles to recover heat from low-temperature flue gas in coal-fired boilers: 1. Corrosion – SO2, SO3, HCl, HF, etc., produced during combustion combine with water vapor in the flue gas and condense on the surface of metal pipes to form a mixture of sulfuric acid, hydrochloric acid, hydrofluoric acid, etc., thereby causing low-temperature corrosion.

[0004] 2. Ash blockage – The condensed mixed acid also adheres to fly ash in the flue gas, forming scale on the metal surface, which aggravates the ash accumulation and blockage inside the equipment. Ammonia escape further exacerbates the degree of ash accumulation and blockage.

[0005] 3. Ash abrasion – Ash in coal-fired flue gas systems contains silica, a highly abrasive material that can cause severe wear on metal surfaces or coatings, leading to heat exchanger failure.

[0006] Traditional air preheaters and flue gas coolers use tubular heat exchange elements, which share common industry pain points: they are prone to clogging, wear, and severe corrosion, resulting in relatively high exhaust gas temperatures, reduced boiler thermal efficiency, and increased fuel consumption. Summary of the Invention

[0007] This invention provides a low-temperature economizer for high-efficiency pulverized coal boilers, which solves at least one of the defects of the above-mentioned background technology, namely that "traditional air preheaters and flue gas coolers use tubular heat exchange elements".

[0008] To solve the above-mentioned technical problems, the present invention discloses a low-temperature economizer for high-efficiency pulverized coal boilers, comprising: A support frame on which a wide-channel plate heat exchanger is connected; The flue gas inlet duct structure is connected to the flue gas inlet side of the wide-channel plate heat exchanger. The exhaust duct structure is connected to the exhaust side of the wide-channel plate heat exchanger.

[0009] Preferably, the flue gas inlet pipe structure includes flue I, flue II, and flue III connected sequentially along the flue gas inlet direction, and flue III of the flue gas inlet pipe structure is connected to the flue gas inlet of the wide-channel plate heat exchanger; The exhaust duct structure includes flue Ⅲ, flue Ⅱ, and flue Ⅳ connected sequentially along the exhaust direction; flue Ⅲ of the exhaust duct structure is connected to the exhaust port of the wide-channel plate heat exchanger.

[0010] Preferably, channel steel and angle steel are provided for flue I, flue II, flue III, and flue IV; Flue I and flue II are connected and linked by connecting structure one. Flue III and flue II of the smoke inlet duct structure are connected and linked by connecting structure two. Flue IV and flue II are connected and linked by connecting structure one. Flue II and flue III of the smoke exhaust duct structure are connected by connecting structure two.

[0011] Preferably, the connection structure one includes: Pipeline 1, the inlet end of which is fixedly installed on the outlet side of the preceding flue along the flue gas flow direction connected by the connecting structure 1, and the outlet end of which is integrally provided with an annular angle steel 1. Pipeline 2, the outlet end of pipeline 2 is fixedly set on the inlet side of the next flue along the flue gas flow direction connected by connecting structure 1, and the inlet end of pipeline 2 is integrally provided with annular angle steel 2. An extension pipe 1 is provided on the side of the annular angle steel 1 that is close to the annular angle steel 2; an extension pipe 2 is provided on the inner side of the pipe 2 that is close to the end of the pipe 1. An annular tube is sleeved on the outside of annular angle steel one and annular angle steel two, and the annular tube is connected to annular angle steel one and annular angle steel two by a detachable connector. The second connection structure includes: a pipe three, with annular extension protrusions on both the inlet and outlet sides of the pipe three. The annular extension protrusions on the inlet side of the pipe three are respectively connected to the angle steel of flue III and the angle steel of flue II.

[0012] Preferably, the shape, length, and installation method of the wear-resistant parts are selected on the windward side of the wide-channel plate heat exchanger according to the shape of the inlet flue, the flue gas velocity, the particle size distribution of ash particles, the hardness of fly ash, and the incident angle. The purpose is to consume the kinetic energy of coarse particles with excessive incident angle and modify their running direction through collision, so as to reduce the wear on the subsequent heat exchange plates.

[0013] Preferably, the wide-channel plate heat exchanger is equipped with a wide-channel corrugated heat exchange plate; The wide-channel corrugated heat exchange plate is made of titanium. The design of the wide-channel corrugated heat exchange plate sets the weld ring pitch and bulge height to ensure that the flue gas flows through the plate in an orderly manner without being in the angle area with greater wear.

[0014] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings and embodiments.

[0015] Compared with the prior art, the present invention has the following beneficial effects: 1. Anti-clogging and anti-corrosion: (1) All economizers use wide-channel self-cleaning plate heat exchangers. Since the plate structure has a straight-through property, and the wide-channel corrugated plate has a self-cleaning function, the heating surface is not easy to accumulate ash. Moreover, the plate spacing can be adjusted according to the flue gas composition. Even if some ash accumulates, the normal operation cycle can be greatly extended.

[0016] (2) Wide flow channel heat exchangers have the characteristic of self-cleaning. Flue gas can carry away floating ash and is not prone to under-deposit corrosion.

[0017] (3) The heat exchanger is made of titanium plate, which is resistant to acid and alkali corrosion and does not easily react with sulfides and ammonia salts in flue gas.

[0018] 2. Wear-resistant: (1) On the windward side of the flue gas cooler, the shape, length and installation method of the wear-resistant parts are selected according to the shape of the inlet flue, the flue gas velocity, the particle size distribution of the ash particles, the hardness of the fly ash and the incident angle. The purpose is to consume the kinetic energy of coarse particles with excessive incident angle and modify their running direction through collision, so as to reduce the wear on the subsequent heat exchange plates.

[0019] (2) When designing the plate, use appropriate welding ring pitch and bulging height to ensure that the flue gas does not scour the plate in an angle area with large wear. At the same time, design a reasonable flow rate to reduce the scouring of dusty flue gas.

[0020] 3. Use ring angle steel + extension pipe + ring pipe (e.g.) Figure 5 The composite connection structure (with sidewalls that can be arc-shaped) transforms the stress on the flue connection from "point contact" to "ring-shaped surface contact," significantly improving the shear and tensile strength of the connection nodes. It can effectively resist the pulsating pressure and long-term vibration generated by flue gas flow, avoiding problems such as loose bolts and cracked welds that are common in traditional flange connections.

[0021] The full-area arrangement of channel steel and angle steel forms a "skeleton" support system for the flue, which significantly enhances the rigidity of the flue body and can adapt to large-span, high-load flue gas transportation scenarios (such as large industrial boilers and power plant flue systems).

[0022] The extension tube 1 of the annular angle steel and the extension tube 2 of the pipe form a nested sealing cavity. Combined with the wrapping connection of the annular pipe, a dual sealing mechanism of "physical barrier + cavity buffer" is constructed, which can effectively block the infiltration of flue gas from the connection gap. Compared with traditional asbestos gasket seals, its sealing life is extended, and it is especially suitable for sealing requirements of high temperature and highly corrosive flue gas.

[0023] The interlocking connection between the annular extension protrusion of the second connecting structure and the angle steel upgrades the sealing surface from a "planar" to a "three-dimensional annular surface," further improving the reliability of the seal and its resistance to deformation.

[0024] The differentiated design of connection structure one and connection structure two can respectively adapt to various connection requirements such as "straight-through flue of the same diameter" and "change of diameter flue of different diameter", so that the solution can be flexibly applied to the integrated layout of multiple systems such as boiler flue and exhaust pipe. Especially in the complex flue network of power plants and chemical plants, it can realize the efficient connection of flues with different functions. Attached Figure Description

[0025] The accompanying drawings are provided to further illustrate the invention and form part of the specification. They are used in conjunction with embodiments of the invention to explain the invention and do not constitute a limitation thereof. In the drawings: Figure 1 This is the overall front view of the present invention; Figure 2 This is an overall side view of the present invention; Figure 3 This is an overall top view of the present invention; Figure 4 for Figure 1 A magnified structural diagram of region A in the diagram; Figure 5 for Figure 1 A magnified structural diagram of region B in the diagram.

[0026] In the diagram: 1. Support; 2. Flue I; 3. Flue II; 4. Flue III; 5. Flue IV; 6. Angle steel; 7. Channel steel; 8. Connection structure I; 81. Pipe I; 82. Annular angle steel I; 83. Pipe II; 84. Annular angle steel II; 85. Extension pipe I; 86. Extension pipe II; 87. Annular pipe; 88. Detachable connector; 9. Connection structure II; 91. Pipe III; 92. Annular extension protrusion; 10. Wide-channel plate heat exchanger. Detailed Implementation

[0027] The preferred embodiments of the present invention will be described below with reference to the accompanying drawings. It should be understood that the preferred embodiments described herein are for illustration and explanation only and are not intended to limit the present invention.

[0028] Furthermore, in this invention, the use of terms such as "first" and "second" is for descriptive purposes only and does not specifically refer to any order or sequence, nor is it intended to limit the invention. They are merely used to distinguish components or operations described using the same technical terms and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Therefore, a feature defined with "first" or "second" may explicitly or implicitly include at least one of those features. Additionally, the technical solutions and features of the various embodiments can be combined with each other, but this must be based on the ability of those skilled in the art to implement them. If a combination of technical solutions is contradictory or impossible to implement, it should be considered that such a combination of technical solutions does not exist and is not within the scope of protection claimed by this invention.

[0029] The present invention provides the following embodiments: Example 1: This embodiment of the invention provides a low-temperature economizer for a high-efficiency pulverized coal boiler, such as... Figures 1-5 As shown, it includes: Support 1, on which a wide-channel plate heat exchanger 10 is connected; The flue gas inlet duct structure is connected to the flue gas inlet side of the wide-channel plate heat exchanger 10. The exhaust duct structure is connected to the exhaust side of the wide-channel plate heat exchanger 10.

[0030] Preferably, the flue gas inlet pipe structure includes flue I2, flue II3, and flue III4 connected sequentially along the flue gas inlet direction, and flue III4 of the flue gas inlet pipe structure is connected to the flue gas inlet of the wide flow channel plate heat exchanger 10. The exhaust duct structure includes flue Ⅲ4, flue Ⅱ3, and flue Ⅳ5 connected sequentially along the exhaust direction; flue Ⅲ4 of the exhaust duct structure is connected to the exhaust port of the wide-channel plate heat exchanger.

[0031] Preferably, channel steel 7 and angle steel 6 are provided for flue I2, flue II3, flue III4, and flue IV5; Flue I2 and flue II3 are connected and linked by connecting structure 18. Flue III4 and flue II3 of the smoke inlet pipe structure are connected and linked by connecting structure 29. Flue IV5 and flue II3 are connected and linked by connecting structure 18. Flue II3 and flue III4 of the smoke exhaust pipe structure are connected by connecting structure 29.

[0032] Preferably, the connection structure 8 includes: Pipeline 81, the inlet end of which is fixedly installed on the outlet side of the previous flue along the flue gas flow direction connected by connecting structure 8, and the outlet end of pipeline 81 is integrally provided with annular angle steel 82. Pipeline 2 83, the outlet end of pipeline 2 83 is fixedly set on the inlet side of the next flue along the flue gas flow direction connected by connecting structure 1 8, and the inlet end of pipeline 2 83 is integrally provided with annular angle steel 2 84. An extension pipe 85 is provided on the side of the annular angle steel 82 near the annular angle steel 84; an extension pipe 86 is provided on the inner side of the pipe 83 near the end of the pipe 81. An annular tube 87 is sleeved on the outside of annular angle steel one 82 and annular angle steel two 84. The annular tube 87 is connected to annular angle steel one 82 and annular angle steel two 84 through a detachable connector 88. The second connection structure 9 includes: a third pipe 91, with annular extension protrusions 92 provided on both the inlet and outlet sides of the third pipe 91. The annular extension protrusions 92 on the inlet side of the third pipe 91 are respectively connected to the angle steel 6 of flue Ⅲ4 and the angle steel 6 of flue Ⅱ3.

[0033] Preferably, the shape, length and installation method of the wear-resistant parts are selected on the windward side of the wide-channel plate heat exchanger 10 according to the shape of the inlet flue, the flue gas velocity, the particle size distribution of ash particles, the hardness of fly ash and the incident angle. The purpose is to consume the kinetic energy of coarse particles with excessive incident angle and modify their running direction through collision, so as to reduce the wear on the subsequent heat exchange plates.

[0034] Preferably, the wide-channel plate heat exchanger is equipped with a wide-channel corrugated heat exchange plate; The wide-channel corrugated heat exchange plate is made of titanium. The design of the wide-channel corrugated heat exchange plate sets the weld ring pitch and bulge height to ensure that the flue gas flows through the plate in an orderly manner without being in the angle area with greater wear.

[0035] This invention can achieve a constant flue gas outlet temperature by controlling the water flow rate inside the heat exchanger.

[0036] The dust removal mode of the present invention can be manual dust removal or automatic timed dust removal.

[0037] The beneficial effects of the above technical solution are as follows: 1. Anti-clogging and anti-corrosion: (1) All economizers use wide-channel self-cleaning plate heat exchangers. Since the plate structure has a straight-through property, and the wide-channel corrugated plate has a self-cleaning function, the heating surface is not easy to accumulate ash. Moreover, the plate spacing can be adjusted according to the flue gas composition. Even if some ash accumulates, the normal operation cycle can be greatly extended.

[0038] (2) Wide flow channel heat exchangers have the characteristic of self-cleaning. Flue gas can carry away floating ash and is not prone to under-deposit corrosion.

[0039] (3) The heat exchanger is made of titanium plate, which is resistant to acid and alkali corrosion and does not easily react with sulfides and ammonia salts in flue gas.

[0040] 2. Wear-resistant: (1) On the windward side of the flue gas cooler, the shape, length and installation method of the wear-resistant parts are selected according to the shape of the inlet flue, the flue gas velocity, the particle size distribution of the ash particles, the hardness of the fly ash and the incident angle. The purpose is to consume the kinetic energy of coarse particles with excessive incident angle and modify their running direction through collision, so as to reduce the wear on the subsequent heat exchange plates.

[0041] (2) When designing the plate, use appropriate welding ring pitch and bulging height to ensure that the flue gas does not scour the plate in an angle area with large wear. At the same time, design a reasonable flow rate to reduce the scouring of dusty flue gas.

[0042] 3. Use ring angle steel + extension pipe + ring pipe (e.g.) Figure 5 The composite connection structure (with sidewalls that can be arc-shaped) transforms the stress on the flue connection from "point contact" to "ring-shaped surface contact," significantly improving the shear and tensile strength of the connection nodes. It can effectively resist the pulsating pressure and long-term vibration generated by flue gas flow, avoiding problems such as loose bolts and cracked welds that are common in traditional flange connections.

[0043] The full-area arrangement of channel steel 7 and angle steel 6 forms a "skeleton" support system for the flue, which significantly enhances the rigidity of the flue body and can adapt to large-span, high-load flue gas transportation scenarios (such as large industrial boilers and power plant flue systems).

[0044] The extension tube 85 of the annular angle steel 82 and the extension tube 86 of the pipe 83 form a nested sealing cavity. Combined with the wrapping connection of the annular pipe 87, a dual sealing mechanism of "physical barrier + cavity buffer" is constructed, which can effectively block the infiltration of flue gas from the connection gap. Compared with traditional asbestos gasket seals, its sealing life is extended, and it is especially suitable for sealing requirements of high temperature and highly corrosive flue gas.

[0045] The interlocking connection between the annular extension protrusion 92 of the connecting structure 29 and the angle steel 6 upgrades the sealing surface from a "planar" to a "three-dimensional annular surface", further improving the reliability of the seal and its resistance to deformation.

[0046] The differentiated design of connection structure 1 (8) and connection structure 2 (9) can respectively adapt to various connection requirements such as "straight-through flue of the same diameter" and "change of diameter flue of different diameter", so that the solution can be flexibly applied to the integrated layout of multiple systems such as boiler flue and exhaust pipe. Especially in the complex flue network of power plants and chemical plants, it can realize the efficient connection of flues with different functions.

[0047] Example 2, based on Example 1, further includes an intelligent monitoring module, which includes: Flue gas dust concentration detection module: used to detect the dust concentration in the flue gas of the flue gas inlet duct structure; Flow velocity detection module 1: Used to detect the flue gas flow velocity at the flue gas inlet of the wide-channel plate heat exchanger 10; Flow velocity detection module 2: Used to detect the flue gas velocity at the flue gas outlet of the wide-channel plate heat exchanger 10; Control Module 1: Used to control the flue gas velocity regulation device of the low-temperature economizer of high-efficiency pulverized coal boiler when assessing whether the flue gas velocity needs to be adjusted, so that the detection value of the velocity detection module 1 is the rated velocity set time. Flow velocity analysis module: used to determine the flow velocity gradient coefficient based on the detection values ​​of flow velocity detection module 2 within a set time period; Analysis Module 1: Used to determine the velocity-dust concentration synergy coefficient based on the velocity gradient coefficient and the detection results of the flue gas dust concentration detection module; Alarm Module 1: Used when the flow velocity-dust content coordination coefficient is not within the corresponding coordination coefficient range (less than the preset value (value is greater than or equal to 1 and less than 1.5); alarms can be triggered based on equipment type (such as the flow channel design and material of a wide flow channel plate heat exchanger) and coal type dust content).

[0048] Flow velocity gradient coefficient = (rated flow velocity - average value detected by flow velocity detection module 2 within a set time period of rated flow velocity) ÷ rated flow velocity; Flow velocity-dust concentration synergy coefficient = Detection value of flue gas dust concentration detection module × Flow velocity gradient coefficient ÷ Reference flue gas dust concentration; The baseline flue gas dust concentration is a pre-set "reference value for flue gas dust concentration under normal operating conditions" used to standardize the calculation of "dust concentration state" and "flow velocity-dust concentration synergy coefficient" to ensure the comparability of parameters under different operating conditions.

[0049] The product of dust concentration (dust concentration detected by the flue gas dust concentration detection module ÷ baseline flue gas dust concentration) and velocity gradient directly reflects the synergistic effect of "dust amount × flow field disturbance degree" (the larger the value, the higher the risk of dust deposition / scouring). If the dust concentration is high, but the velocity gradient is small (uniform flow field), the dust may be deposited uniformly due to the smooth flow. If the velocity gradient is large but the dust concentration is low, the flow field disturbance lacks "sufficient dust" to support it, and will not cause serious dust accumulation / scouring. The product value will only increase significantly when there is a large amount of dust and strong flow field disturbance. At this time, the dust will impact the plate (scouring) or accumulate in the eddy zone (deposition) due to strong disturbance, eventually leading to plate wear or a sharp increase in thermal resistance.

[0050] In this scheme, the rated flow rate refers to the pre-set standard design flow rate at the flue gas inlet of the wide-channel plate heat exchanger 10, which serves as the benchmark reference value for the entire flow rate control and risk assessment system. Essentially, it is the target flue gas inlet flow rate set under normal operating conditions based on factors such as the design performance of the equipment (wide-channel plate heat exchanger 10) and flue gas treatment requirements (e.g., heat exchange efficiency, dust carrying capacity).

[0051] The beneficial effects of the above technical solution are as follows: Based on the "flow rate-dust co-coefficient", early risk warning can identify problems in advance at the "early stage of dust deposition / equipment scouring risk", avoiding serious failures such as equipment blockage and plate wear caused by traditional "post-event alarm", and significantly reducing operation and maintenance costs and downtime losses.

[0052] The scientific and efficient flow rate control module uses the "rated flow rate" as the control benchmark and combines the dynamic analysis of the flow rate gradient coefficient to keep the inlet flow rate of the wide-channel plate heat exchanger always within the design optimal range. This ensures heat exchange efficiency (stable flow rate is conducive to heat exchange) and also controls dust deposition through flow field optimization, achieving the dual benefits of "heat exchange + dust prevention".

[0053] The intelligent and economical system operation and maintenance achieves automated operation through modular detection, analysis and control modules, reducing the workload of manual inspection and the risk of misjudgment; at the same time, accurate risk warning can avoid unnecessary dust cleaning or maintenance actions, extend the equipment maintenance cycle, and significantly improve the economic efficiency of the system throughout its entire life cycle.

[0054] Example 3, based on Example 2, further includes the following intelligent monitoring module: Temperature detection module 1: Used to detect the flue gas temperature at the flue gas inlet and the flue gas temperature at the flue gas outlet of the wide flow channel plate heat exchanger. Temperature detection module 2: Used to detect the temperature of the cold fluid inlet of the wide-channel plate heat exchanger; Heat exchange evaluation module: used to determine the equivalent heat exchange efficiency and flue gas temperature difference-flow velocity coordination coefficient based on the detection values ​​of temperature detection module 1, temperature detection module 2, and flow velocity detection module 2 within the set time period (30S to 5min); Storage module: Stores flue gas velocity-reference flue gas heat exchange efficiency curve; Correction module: When the equivalent heat exchange efficiency is less than the required heat exchange efficiency range (the required heat exchange efficiency range under the current heat exchange state) and alarm module 1 does not alarm, the flue gas velocity-reference flue gas heat exchange efficiency curve is corrected by the flue gas temperature difference-flow velocity coordination coefficient. The filtering and segmentation module is used to filter the target segment of the flue gas heat exchange efficiency curve from the flue gas velocity-corrected reference flue gas heat exchange efficiency curve. The target segment has a corrected reference flue gas heat exchange efficiency of K times (K is greater than 1 and less than 1.5) within the required heat exchange efficiency range and the flow velocity is greater than the rated flow velocity. The target segment is divided into multiple curve sub-segments. The flow velocity of each curve sub-segment is continuous, and the absolute value of the difference between the maximum value and the minimum value of the corrected reference flue gas heat exchange efficiency of each curve sub-segment is less than the preset segmentation difference (which can be 0.02 to 0.2). The curve sub-segments are numbered in ascending order of flow velocity. Test flow rate screening module: used to determine the flow rate corresponding to the median flue gas heat exchange efficiency of each curve segment as the initial test flow rate; Control module one determines the target flow rate based on the initial test flow rate test, and controls the flue gas inlet flow rate to the target flow rate for continuous operation.

[0055] Control module one controls the flue gas inlet velocity sequentially to different initial test velocities in ascending order of flow velocity, and sets a working time for each initial test velocity to determine the test equivalent heat transfer efficiency corresponding to each initial test velocity, until the test equivalent heat transfer efficiency is greater than or equal to the median of the required heat transfer efficiency for the first time; the initial test velocities in which the test equivalent heat transfer efficiency is greater than or equal to the median of the required heat transfer efficiency are determined as the target flow velocities.

[0056] Equivalent heat transfer efficiency = ;in, The average value of the flue gas temperature detected at the flue gas inlet of the wide-channel plate heat exchanger within a set time period; The average value of the flue gas temperature detected at the flue gas outlet of the wide-channel plate heat exchanger within a set time period; The average temperature of the cold fluid inlet of the flow channel plate heat exchanger is the average value within a set time period; the equivalent heat exchange efficiency quantifies the heat exchange effect between the flue gas and the cold fluid. The numerator is the temperature drop of the flue gas, and the denominator is the initial temperature difference between the flue gas and the cold fluid. The closer the value is to 1, the more sufficient the heat exchange is.

[0057] Flue gas temperature difference - velocity coordination coefficient = ; The flue gas temperature at the flue gas inlet of the wide-channel plate heat exchanger is At that time, the theoretical flue gas temperature at the flue gas outlet of the wide-channel plate heat exchanger within the set time period; The rated flow rate (the standard flue gas velocity during the design or normal operation of a wide-channel plate heat exchanger, which is a preset flow rate of the equipment under ideal operating conditions (such as initial clean state, with heat exchange parameters as the reference parameters), is used as a reference for flue gas velocity. The average detection value of the flow velocity detection module 2 within the set time period corresponding to the rated flow velocity; for The corresponding theoretical value; ; This is the theoretical average detection value of the flow velocity detection module two within the set time period corresponding to the rated flow velocity; The synergistic relationship between "actual flue gas cooling effect" and "flow rate matching degree" is quantified. The closer the value is to 1, the better the matching degree between flow rate and heat exchange.

[0058] This refers to the theoretical value of the flue gas outlet temperature calculated based on design parameters and a thermodynamic model for a wide-channel plate heat exchanger under initial clean conditions. Specifically, it refers to the value at the flue gas inlet temperature when the wide-channel plate heat exchanger is in its "initial use (clean state without ash or scale)". The theoretical outlet temperature of the flue gas, calculated using the heat exchange design model, is the temperature at which the heat exchange fluid parameters are taken (when the heat exchange fluid parameters are the baseline / rated parameters; the heat exchange parameters in actual operation can also be the baseline parameters). It is the "expected outlet temperature" of the equipment under ideal operating conditions and is used as a benchmark for judging heat exchange efficiency and ash accumulation during subsequent operation.

[0059] Specifically, when the heat exchanger is running at its rated flow rate, the flow rate detection module two (a device for detecting flue gas velocity) calculates the average flow rate value over a set time period based on ideal operating conditions (such as an initial clean state with no ash accumulation or scaling). It is one of the key parameters in the flue gas temperature difference-flow rate compatibility formula used to quantify flow rate matching, and is related to the rated flow rate. They jointly participate in the calculation of the collaborative relationship between "actual flow velocity and heat transfer matching degree".

[0060] The "flue gas velocity-reference flue gas heat transfer efficiency curve" is a benchmark curve used to quantify the relationship between flue gas velocity and heat transfer efficiency (equivalent flue gas heat transfer efficiency). The specific explanation is as follows: This curve has flue gas velocity as the horizontal axis and reference flue gas heat transfer efficiency as the vertical axis. It is a curve showing the relationship between "flow velocity and heat transfer efficiency" obtained through experiments or simulation calculations under the "initial clean state (no dust accumulation, no scaling)" of the heat exchanger.

[0061] During construction, the corresponding flue gas heat exchange efficiency is tested or calculated at different flue gas velocities (covering the flow rate range designed for the equipment) (based on ideal state data from the temperature detection module and flow rate detection module). These "flow rate-efficiency" data points are fitted into a continuous curve, which serves as a benchmark for the equipment's heat exchange performance.

[0062] The corrected reference flue gas heat transfer efficiency corresponding to the current flow rate in the corrected flue gas velocity-reference flue gas heat transfer efficiency curve is the reference flue gas heat transfer efficiency corresponding to the current flow rate in the original flue gas velocity-reference flue gas heat transfer efficiency curve × flue gas temperature difference - flow velocity coordination coefficient. The beneficial effects of the above technical solution are as follows: By collecting multi-dimensional data from temperature and flow rate detection modules, and combining the quantitative calculation of equivalent heat exchange efficiency and flue gas temperature difference-flow rate synergy coefficient, the real-time heat exchange performance of the heat exchanger can be accurately evaluated. This breaks through the limitations of traditional single temperature detection and enables refined analysis of the correlation between temperature, flow rate and heat exchange efficiency.

[0063] When the heat exchange efficiency deviates from the requirements, the correction module corrects the baseline curve through the coordination coefficient, so that the heat exchange efficiency assessment is more in line with the actual operating conditions (such as non-ideal conditions such as ash accumulation and scaling), and ensures the dynamic optimization of heat exchange efficiency.

[0064] The filtering and segmentation module performs fine-grained interval division on the corrected curve, ensuring that the flow velocity is continuous and the heat exchange efficiency fluctuation is controllable within each segment (the difference is less than the preset interval difference), providing a precise interval basis for subsequent flow velocity control and realizing the transformation from "extensive operation" to "refined adaptation".

[0065] The test flow rate screening and control module determines the target flow rate based on the median efficiency of the sub-segment, so that the matching between the flue gas velocity and the heat exchange efficiency is optimal, and the heat exchanger can maintain high-efficiency operation under different operating conditions.

[0066] Precise flow rate control can avoid energy waste caused by excessive flow rate or insufficient heat exchange caused by insufficient flow rate, thus achieving energy saving and consumption reduction.

[0067] By monitoring and correcting, abnormal changes in heat exchange efficiency (such as in the early stages of ash accumulation) can be detected in a timely manner, avoiding problems such as equipment overload and increased scaling caused by persistently low heat exchange efficiency, and extending the service life of the equipment.

[0068] Using the "median heat exchange efficiency" as the threshold, the heat exchange efficiency corresponding to the target flow rate is ensured to be at a reasonable upper level within the demand range. This avoids insufficient heat exchange due to selecting a flow rate with too low efficiency, fundamentally guaranteeing the heat exchange performance of the wide-channel plate heat exchanger and meeting the core requirements of the process for heat exchange effect.

[0069] By employing a logic of "testing sequentially from small to large + locking in the target upon first success," redundant and repetitive testing is eliminated, significantly shortening the time required to determine the target flow rate. This allows the heat exchanger to quickly enter a high-efficiency operating state, improving the system's response speed and operational efficiency. Furthermore, if subsequent operating efficiency decreases, an initial test flow rate higher than the target flow rate can be selected to determine a suitable flow rate.

[0070] Example 4, based on any one of Examples 1-3, further includes a dust removal control device, the dust removal control device comprising: Pressure sensor 1: Used to detect the gas pressure at the flue gas inlet of a flow channel plate heat exchanger; Pressure sensor 2: Used to detect the gas pressure at the flue gas outlet of the flow channel plate heat exchanger; Runtime detection module: Used to detect the runtime of the flow channel plate heat exchanger; Flow sensor: Used to detect the flue gas flow rate at the flue gas inlet of a flow channel plate heat exchanger; Flue gas dust concentration detection module: used to detect the dust concentration in the flue gas of the flue gas inlet duct structure; The dust removal early warning module is used to periodically determine the difference between the average detection value of pressure sensor 1 and the average detection value of pressure sensor 2 within the latest time period (which can be 1 to 5 minutes). When the difference is greater than a preset difference, a dust removal early warning is issued. Ash accumulation analysis module: used to periodically determine ash accumulation parameters based on the latest values ​​detected by pressure sensor 1, pressure sensor 2, runtime detection module, and flow sensor within a certain time period; Dust accumulation parameter = [(Average detection value of pressure sensor 1 in the latter half of the latest duration 1 - Average detection value of pressure sensor 2 in the latter half of the latest duration 1) - (Average detection value of pressure sensor 1 in the first half of the latest duration 1 - Average detection value of pressure sensor 2 in the first half of the latest duration 1)] ÷ 0.5 times duration 1 ÷ Average detection value of flow sensor in the latest duration ÷ Average detection value of flue gas dust concentration detection module in the latest duration; When the two are coupled, the larger the ash accumulation parameter, the higher the degree of abnormality of the flow channel resistance change caused by ash accumulation under low flow / low concentration conditions, which accurately captures this type of ash accumulation scenario that is easily overlooked.

[0071] Dust accumulation early warning module: Used to issue an early warning when the dust accumulation parameter is greater than the preset dust accumulation parameter, reminding you to adjust the dust concentration entering the flue structure.

[0072] In this invention, a dust removal device is installed before the flue gas inlet duct structure, so that the flue gas can directly enter the flue gas inlet duct structure or pass through the dust removal device before entering the flue gas inlet duct structure.

[0073] When dust accumulation at low flow / low concentration causes a sudden change in air pressure difference (dust removal warning) or when dust accumulation parameters exceed the standard (dust accumulation warning), it promptly reminds you to adjust the dust concentration in the flue gas inlet (such as switching the operating mode of the dust removal device, which is more prone to dust accumulation (possibly due to factors such as dust particles), so the amount of dust needs to be adjusted), filling the blind spot in dust accumulation prevention and control under low flow / low concentration conditions.

[0074] The beneficial effects of the above technical solution are as follows: Dust removal early warning module: Based on the pressure difference between the inlet and outlet, an early warning is triggered, and an immediate response to "sudden blockage" is achieved in case of emergency caused by sudden changes in flow resistance; Ash accumulation early warning module: Based on ash accumulation parameters, it triggers early warnings to intervene in potential risks in advance for chronic ash accumulation trends under low flow / low concentration conditions.

[0075] The two-tiered early warning mechanism forms a complete risk prevention and control chain, ensuring that the problem of dust accumulation can be dealt with in a timely manner at different stages of development.

[0076] The solution is specifically optimized for often overlooked industrial production conditions such as "low flow / low concentration," filling the blind spot in dust accumulation control under these conditions. Whether it's low-load scenarios like equipment start-up and shutdown or process adjustments, or regular low-flow periods during operation, it ensures the effectiveness of dust accumulation monitoring and improves the system's adaptability under all operating conditions.

[0077] Obviously, those skilled in the art can make various modifications and variations to this invention without departing from its spirit and scope. Therefore, if these modifications and variations fall within the scope of the claims of this invention and their equivalents, this invention also intends to include these modifications and variations.

Claims

1. A low-temperature economizer for high-efficiency pulverized coal boilers, characterized in that: include: A support (1) is provided, on which a wide-channel plate heat exchanger (10) is connected; The flue gas inlet pipe structure is connected to the flue gas inlet side of the wide flow channel plate heat exchanger (10); The exhaust duct structure is connected to the exhaust side of the wide-channel plate heat exchanger (10).

2. The high-efficiency pulverized coal boiler low-temperature economizer according to claim 1, characterized in that: The flue gas inlet structure includes flue I (2), flue II (3) and flue III (4) connected sequentially along the flue gas inlet direction. Flue III (4) of the flue gas inlet structure is connected to the flue gas inlet of the wide flow channel plate heat exchanger (10). The exhaust pipe structure includes flue Ⅲ (4), flue Ⅱ (3), and flue Ⅳ (5) connected sequentially along the exhaust direction; flue Ⅲ (4) of the exhaust pipe structure is connected to the exhaust port of the wide-channel plate heat exchanger.

3. The high-efficiency pulverized coal boiler low-temperature economizer according to claim 1, characterized in that: Channel steel (7) and angle steel (6) are installed in flue I (2), flue II (3), flue III (4) and flue IV (5).

4. The high-efficiency pulverized coal boiler low-temperature economizer according to claim 2, characterized in that: Flue I (2) and flue II (3) are connected and connected by connecting structure one (8). Flue III (4) and flue II (3) of the smoke inlet pipe structure are connected and connected by connecting structure two (9). Flue IV (5) and flue II (3) are connected and connected by connecting structure one (8). Flue II (3) and flue III (4) of the smoke exhaust pipe structure are connected by connecting structure two (9).

5. The high-efficiency pulverized coal boiler low-temperature economizer according to claim 4, characterized in that: The connection structure one (8) includes: Pipeline 1 (81), the inlet end of which is fixedly set on the outlet side of the previous flue connected by the connecting structure 1 (8) along the flue gas flow direction, and the outlet end of the pipe 1 (81) is integrally set with an annular angle steel 1 (82). Pipeline 2 (83), the outlet end of pipeline 2 (83) is fixedly set on the inlet side of the next flue connected along the flue gas flow direction by the connecting structure 1 (8), and the inlet end of pipeline 2 (83) is integrally set with annular angle steel 2 (84); An extension pipe 1 (85) is provided on the side of the annular angle steel 1 (82) near the annular angle steel 2 (84); an extension pipe 2 (86) is provided on the inner side of the pipe 2 (83) near the end of the pipe 1 (81); The annular tube (87) is sleeved on the outside of the annular angle steel one (82) and the annular angle steel two (84). The annular tube (87) is connected to the annular angle steel one (82) and the annular angle steel two (84) through a detachable connector (88). The second connection structure (9) includes: a third pipe (91), wherein both the inlet and outlet sides of the third pipe (91) are provided with annular extension protrusions (92), and the annular extension protrusions (92) on the inlet side of the third pipe (91) are connected to the angle steel (6) of flue III (4) and the angle steel (6) of flue II (3) respectively.

6. The high-efficiency pulverized coal boiler low-temperature economizer according to claim 1, characterized in that: The shape, length and installation method of wear-resistant parts are selected on the windward side of the wide-channel plate heat exchanger (10) according to the shape of the inlet flue, flue gas velocity, particle size distribution of ash particles, fly ash hardness and incident angle. The purpose is to consume the kinetic energy of coarse particles with excessive incident angle and modify their running direction through collision, so as to reduce the wear on the subsequent heat exchange plates.

7. The high-efficiency pulverized coal boiler low-temperature economizer according to claim 1, characterized in that: Wide-channel plate heat exchanger (10) is equipped with wide-channel corrugated heat exchange plates; the plate design of the wide-channel corrugated heat exchange plates is configured with weld ring pitch and bulging height.

8. The high-efficiency pulverized coal boiler low-temperature economizer according to claim 1, characterized in that: The wide-channel corrugated heat exchange plate is made of titanium.

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