Intelligent air pre-heater and method for accurately controlling exhaust gas temperature

Abstract

The invention relates to an intelligent air pre-heater and a method for accurately controlling exhaust gas temperature, the intelligent air pre-heater comprises a heat absorption space, a heat exchange unit is accommodated in the heat absorption space, and the heat absorption space is used for enabling the heat exchange unit to be in full contact with flue gas and absorbing heat energy in the flue gas; a heat exchange unit is contained in the heat exchange space, and the heat exchange space is used for enabling the heat exchange unit to make full contact with normal-temperature air and releasing absorbed heat; the heat exchange unit transfer equipment is used for achieving circulating conveying of the heat exchange units in the heat absorption space and the heat exchange space heat exchange units to form heat exchange circulation; the temperature monitoring equipment is used for collecting the working temperature of the boiler in real time; and the control system is used for selecting different heat exchange units to participate in heat exchange circulation according to the received temperature data. Efficient heat exchange of the boiler in different working states or temperature sections is achieved, and the smoke problem can be accurately controlled.

Description

Technical Field

[0001] The invention belongs to the technical field of air preheaters and relates to an intelligent air preheater and a method for accurately controlling exhaust gas temperature. Background Art

[0002] Air preheater (referred to as air preheater) is a heat exchange equipment widely used in industrial boilers, power plants, chemical plants and other fields. Its main function is to use the waste heat of flue gas to preheat the air entering the combustion chamber, thereby improving combustion efficiency, saving energy and reducing pollutant emissions. Traditional air preheaters mostly use tubular or plate structures. Although they can achieve heat exchange to a certain extent, they have problems such as low heat exchange efficiency, easy ash accumulation and high maintenance cost under high-temperature flue gas conditions.

[0003] In recent years, air preheaters based on spherical heat exchange units have gradually attracted attention due to their performance advantages of efficient heat exchange, high flexibility, strong anti-ash ability and high temperature resistance. However, in actual use, the phase change temperature of specific phase change materials in the heat exchange unit is fixed, resulting in the inability of the equipment to achieve efficient heat exchange under different working conditions (such as startup, full load, and shutdown stages). In addition, large-scale equipment has long startup and shutdown times, large operating temperature changes, and high cost and difficulty in replacing phase change materials. At the same time, there is currently a lack of effective control methods to accurately control the degree of reduction in flue gas temperature. If the flue gas temperature is reduced too low, it will cause condensation of salt substances in the flue gas, forming ash accumulation, blocking the heat exchange space, and reducing the heat exchange efficiency. Summary of the invention

[0004] The purpose of the present invention is to solve the above problems and provide an intelligent air preheater and a method for accurately controlling the exhaust gas temperature.

[0005] To achieve the above object, the present invention provides an intelligent air preheater, comprising:

[0006] The heat absorbing space contains a heat exchanging unit, which is used to make the heat exchanging unit in the heat absorbing space fully contact with the flue gas and absorb the heat energy in the flue gas;

[0007] The heat exchange space contains a heat exchange unit, which is used to make the heat exchange unit in the heat exchange space fully contact with the air at normal temperature and release the absorbed heat;

[0008] A heat exchange unit transfer device, used to transfer the heat exchange unit in the heat absorption space to the heat exchange space and to transfer the heat exchange unit in the heat exchange space to the heat absorption space, so as to form a heat exchange cycle;

[0009] It also includes temperature monitoring equipment for collecting the temperature of boiler flue gas in real time;

[0010] A plurality of spare bins, each of which stores heat exchange units with different phase change temperatures;

[0011] A control system for selecting different heat exchange units to participate in a heat exchange cycle according to received temperature data;

[0012] The heat exchange unit selection device automatically selects the corresponding heat exchange unit to participate in the heat exchange cycle according to the instructions of the control system.

[0013] Furthermore, the heat exchange unit comprises:

[0014] Paraffin phase change material, phase change temperature is 160℃;

[0015] Fatty acid phase change material, phase change temperature is 200℃;

[0016] Salt phase change material, phase change temperature is 240℃,

[0017] Polymer phase change material, phase change temperature is 280℃.

[0018] The present invention also provides a method for accurately controlling flue gas temperature, comprising:

[0019] Multiple equally spaced anti-interference infrared temperature acquisition devices are longitudinally arranged inside the heat absorption space to collect the temperature of the heat exchange unit at different heights. The heat absorption efficiency of the heat absorption unit is determined by analyzing the temperature gradient at different heights. According to the temperature monitoring results, the control system dynamically adjusts the frequency and residence time of the heat exchange unit.

[0020] Install pressure, flow rate, temperature and other sensors at the entrance and exit of the heat absorption space to monitor the parameters of the flue gas in real time. Use the PID control algorithm to dynamically adjust the number and residence time of the heat exchange units according to the deviation between the set value and the actual value of the flue gas outlet temperature to keep the flue gas outlet temperature within the target range. The specific contents include:

[0021] 1.PID control algorithm parameter adjustment mechanism:

[0022] (1) Proportional coefficient (Kp) adjustment strategy: Dynamically adjust according to the current flue gas flow rate (v), the deviation between the inlet temperature (t1) and the set outlet temperature (t_set) (e = t_set-t0) and the real-time heat transfer coefficient (h) of the heat exchange unit. When the absolute value of the deviation |e|>10℃ and the flue gas flow rate v>[V1]m 3 / s (determined by the rated flow of the equipment), Kp=0.5+0.05×(|e|-10)×(v-[V1]) / [ΔV]; when |e|≤10℃, Kp=0.5-0.03×(10-|e|), ensuring the balance between fast response and stable control and avoiding overshoot oscillation. This adjustment strategy has been optimized through multi-condition simulation to improve control accuracy and response speed.

[0023] (2) Dynamic adjustment rule of integral coefficient (Ki): Adjust according to the deviation integral value (∫e dt) and the heat capacity of the heat exchange unit (C = m × c, m is the mass of the phase change medium, c is the specific heat capacity) and the system time constant (τ = L × h / (v × ρ × Cp), L is the number of heat exchange unit layers, ρ is the flue gas density, and Cp is the specific heat capacity of the flue gas). Ki = 0.01 × (∫e dt) / (C × τ), the integral time window is set to [ΔT]s, and Ki is corrected according to the real-time integral value to eliminate the steady-state error and ensure that the outlet temperature is accurate and constant. This rule is derived based on thermal balance and control theory and is adapted to the thermal characteristics of the equipment.

[0024] (3) Differential coefficient (Kd) optimization mechanism: According to the temperature change rate (de / dt) and the flue gas flow rate fluctuation range (±[Δv]m 3 / s) adjustment. Kd=0.1×(de / dt) / (v+[Δv]), enhances the response to temperature mutation, suppresses fluctuations caused by interference, and the coefficient is dynamically optimized according to the flow rate. It is derived from the coupling analysis of thermal flow and fluid mechanics to improve control robustness.

[0025] 2. Heat exchange unit layout parameters:

[0026] (1) Calculation model for the number of layers (L): L = INT[(R-[ΔR]) / (r+[Δr])], where R is the effective radius of the heat exchange space (excluding wall thermal resistance and installation margin), and r is the outer radius of the heat exchange unit. [ΔR] and [Δr] are determined based on engineering experience and heat conduction simulation to ensure compact layout and efficient heat exchange, avoid channel blockage and dead zone heat loss. The model is verified by simulation and experiment to achieve the optimal number of layers.

[0027] (2) Spacing determination: The spacing between heat exchange units on the same layer is determined to be [X1]-[X2] mm according to the flue gas Pr number (Pr = Cp × μ / k, μ is dynamic viscosity, k is thermal conductivity) and Reynolds number (Re = v × d / μ, d is characteristic length). When the Pr number is 0.6-0.8, the spacing is [X1] mm; when the Pr number is 0.8-1.2, the spacing increases linearly to [X2] mm to ensure uniform flue gas flow and enhance convective heat transfer. Based on the correlation optimization of heat and mass transfer theory and experiments, the overall heat transfer performance is improved.

[0028] 3. Control accuracy parameters

[0029] (1) Target range: [t0]℃-[t1]℃ is determined based on the flue gas composition (SO2, H2O, etc.) dew point temperature model (t_d=f(S,P,φ), S is the mole fraction of the component, P is the pressure, φ is the relative humidity) and the equipment acid dew point corrosion safety margin ([Δt]℃). For example, sulfur content

[0030] When [S1]%, pressure [P1]Pa, and humidity φ=[φ1]%, t_d+[Δt]=t0, t1=t0+5℃ (to prevent low-temperature corrosion and dust accumulation and blockage), the equipment life and stable operation are guaranteed. The model is determined through thermodynamic and chemical corrosion research.

[0031] (2) Adjustment accuracy: The adjustment accuracy of the number of heat exchange units is ±1 (determined by the system's minimum operable unit and thermal inertia); the dwell time timing accuracy is ±0.5 seconds (guaranteed by the control system's clock crystal accuracy and timing algorithm optimization), ensuring accurate and reliable control. It has been tested and verified to meet high-precision control requirements, improving system operation quality and energy efficiency.

[0032] The beneficial effects of the present invention are as follows:

[0033] The intelligent air preheater and the method for accurately controlling the exhaust gas temperature of the present invention have significant effects. In terms of heat exchange, by means of heat exchange units with multiple phase change temperatures and intelligent selection and control mechanisms, materials are accurately switched according to the working conditions to achieve efficient heat exchange under all working conditions, greatly improving the efficiency of heat energy conversion and storage. For example, paraffin phase change materials help to quickly heat up during the startup phase, and polymers ensure stable and efficient heat exchange when fully loaded. In terms of cost-effectiveness, the flexible use of multiple phase change materials reduces production and processing costs, avoids the energy efficiency loss and frequent maintenance investment of a single material under different working conditions, and the heat exchange units are independently replaceable, which significantly shortens downtime, reduces operation and maintenance costs, improves equipment utilization, and enhances overall economic benefits. In terms of system stability, the intelligent temperature control system automatically adjusts the heat exchange unit according to temperature changes by relying on real-time and accurate temperature monitoring and intelligent control strategies, effectively reducing the risk of human errors, and ensuring stable and reliable operation of the system through advanced algorithm optimization and dynamic parameter adjustment, extending the service life of the equipment, and enhancing the ability to cope with complex working conditions. In the flue gas heat exchange process, the unique spherical or elliptical heat exchange unit design prolongs the contact time between the flue gas and the medium, expands the contact area, sets the layout parameters according to the flue gas characteristics, strengthens the convective heat exchange, balances the airflow distribution, ensures the full transfer of heat, and improves the overall heat exchange efficiency. In terms of precise temperature control, relying on multi-sensor collaboration, advanced PID algorithms and dynamic optimization parameters, the flue gas outlet temperature is accurately controlled within a predetermined range, dew point corrosion and dust accumulation are eliminated, control accuracy is improved, operating parameters are stabilized, equipment safety lines are strengthened, and system operation quality and energy efficiency are optimized, providing a full range of excellent solutions for industrial heat exchange. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 The structure diagram of an intelligent air preheater according to an embodiment of the present invention is schematically shown.

[0035] Figure 2 The figure schematically shows the arrangement of a heat absorption space temperature collection device according to one embodiment of the present invention. DETAILED DESCRIPTION

[0036] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments are briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention, and for ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0037] The present invention will be described in detail below in conjunction with the accompanying drawings and specific embodiments. The embodiments cannot be described one by one here, but the embodiments of the present invention are not therefore limited to the following embodiments.

[0038] like Figure 1 As shown, the present invention provides a heat exchange unit detection system based on a spherical heat exchange unit, comprising: a heat absorption space 1, a heat exchange space 2, a heat exchange unit transfer device 3, a plurality of spare bins 4, a temperature monitoring device, a control system and a heat exchange unit selection device.

[0039] The heat absorption space 1 is responsible for accommodating a heat exchange unit, which is used to make the heat exchange unit in the heat absorption space 1 fully contact with the flue gas and absorb the heat energy in the flue gas. The heat exchange space 2 is responsible for accommodating a heat exchange unit, which is used to make the heat exchange unit in the heat exchange space 2 fully contact with the normal temperature air and release the absorbed heat. The heat exchange unit transfer device 3 is set as a circulation lift in this embodiment, which is used to realize the transfer of the heat exchange unit in the heat absorption space 1 to the heat exchange space 2 and the transfer of the heat exchange unit in the heat exchange space 2 to the heat absorption space 1. Multiple spare bins, each of which stores heat exchange units with different phase change temperatures. The temperature monitoring device is used to collect the temperature of the boiler flue gas in real time. The control system is used to select different heat exchange units to participate in the heat exchange cycle according to the received temperature data. The heat exchange unit selection device automatically selects the corresponding heat exchange unit to participate in the heat exchange cycle according to the instructions of the control system, and can be specifically set to a manipulator grasping structure, etc.

[0040] Specifically, the heat exchange unit includes an outer shell and a phase change material encapsulated in the outer shell, and the shape is spherical or elliptical. In the present invention, the following phase change media with phase change temperatures between 150°-300° are selected: Paraffin phase change material: the phase change temperature is about 160°C, with high heat capacity and good stability. Fatty acid phase change material: the phase change temperature is about 200°C, which is suitable for medium temperature heat exchange scenarios. Salt phase change material (such as calcium chloride hexahydrate): the phase change temperature is about 240°C, with high thermal conductivity and heat capacity. Polymer phase change material: the phase change temperature is about 280°C, with a long service life and good durability. The heat exchange unit encapsulated with heat exchange media with different phase change temperatures can have different colors or sizes and be stored in different spare bins 4.

[0041] In the intelligent air preheater of the present invention, the working principle is as follows:

[0042] Start-up phase: Use a heat exchange unit encapsulated with paraffin-based phase change material (phase change temperature of approximately 160°C).

[0043] Stage of heating to 200°C: gradually replaced with heat exchange units encapsulated with fatty acid phase change materials (phase change temperature of about 200°C).

[0044] Heating to 250°C stage: Continue to replace with a heat exchange unit encapsulated with salt phase change material (phase change temperature is about 240°C).

[0045] Full load stage (300°C): A heat exchange unit encapsulated with a polymer phase change material (phase change temperature of approximately 280°C) is used to ensure efficient heat exchange performance at the highest operating temperature.

[0046] Cooling stage:

[0047] When the boiler operating temperature drops to about 260°C, the heat exchange units encapsulating polymer phase change materials are gradually replaced by heat exchange units encapsulating salt phase change materials.

[0048] When the operating temperature continues to drop to about 210°C, it is replaced with a heat exchange unit encapsulating fatty acid phase change material.

[0049] When the boiler is close to shutdown and the operating temperature drops below about 170°C, the heat exchange unit encapsulated with paraffin-based phase change materials is eventually replaced to prepare for the next startup phase.

[0050] During the entire process, the temperature monitoring equipment continuously monitors the operating temperature of the boiler, and automatically selects and dispatches the appropriate heat exchange unit for heat exchange through the control system to ensure the efficiency and stability of the heat exchange process.

[0051] The intelligent air preheater of the present invention has the following advantages:

[0052] Efficiently adapt to different working conditions: By using a variety of phase change media with phase change temperatures between 150°-300° and encapsulating them in a movable heat exchange unit, the system can intelligently select the most suitable heat exchange unit for heat exchange according to the different working conditions and temperature ranges of the boiler. This not only ensures the efficient operation of the equipment under different working conditions, but also significantly improves the conversion and storage efficiency of thermal energy.

[0053] Reduce costs and improve economic benefits: Multiple groups of heat exchange units encapsulate heat exchange media with different phase change temperatures, which can be flexibly selected and used according to actual needs, avoiding the problem of low heat exchange efficiency of a single phase change material under different working conditions. This not only reduces the production and processing costs of heat exchange equipment, but also reduces the complexity of later maintenance and replacement, thereby improving the overall economic benefits.

[0054] Enhanced system reliability and stability: The system is equipped with advanced temperature monitoring equipment and intelligent control systems, which can collect and monitor the working temperature of the boiler in real time, and automatically select and dispatch appropriate heat exchange units according to temperature changes. This intelligent control method effectively reduces the risk of human operating errors and enhances the reliability and stability of the system.

[0055] Optimize the contact time between flue gas and heat exchange medium: Compared with the traditional tubular heat exchanger, the heat exchange unit in this solution adopts a spherical or elliptical design, and the contact time between flue gas and heat exchange medium is longer. This not only improves the transfer efficiency of heat energy, but also ensures sufficient contact between flue gas and heat exchange medium, further improving the heat exchange effect.

[0056] Simplified maintenance process: The heat exchange unit can be replaced independently, which makes maintenance simple. When a heat exchange unit fails or needs to be replaced, it can be removed from the system and replaced with a new one, without the need for large-scale disassembly and repair of the entire system. This not only simplifies the maintenance process, but also shortens downtime and improves equipment utilization.

[0057] Wide applicability: The system is not only suitable for industrial equipment such as large boilers, but can also be used in other occasions that require efficient heat exchange. Its flexibility and scalability make it widely applicable and can meet the needs of different fields and scenarios.

[0058] The present invention also provides a method for accurately controlling the flue gas temperature based on the above-mentioned intelligent air preheater. The technical solution of the present invention only focuses on the control method of the number and residence time of the heat exchange units in the heat absorption space under the premise of ensuring that the temperature of the flue gas after flowing through the heat absorption space is higher than the condensation temperature. Figure 2 As shown, the method includes longitudinally setting a plurality of equally spaced anti-interference infrared temperature acquisition devices inside the heat absorption space to collect the temperature of the heat exchange unit at different heights, and judging the heat absorption efficiency of the heat absorption unit by analyzing the temperature gradient at different heights. According to the temperature monitoring results, the control system dynamically adjusts the delivery frequency and residence time of the heat exchange unit; installs pressure, flow rate, temperature and other sensors at the inlet and outlet of the heat absorption space to monitor the parameters of the flue gas in real time, and uses the PID control algorithm to dynamically adjust the number and residence time of the heat exchange unit according to the deviation between the set value and the actual value of the flue gas outlet temperature, so that the flue gas outlet temperature is kept within the target range. The specific calculation method and logic are as follows:

[0059] 1.PID control algorithm parameter adjustment mechanism:

[0060] (1) Proportional coefficient (Kp) adjustment strategy: Dynamically adjust according to the current flue gas flow rate (v), the deviation between the inlet temperature (t1) and the set outlet temperature (t_set) (e = t_set-t0) and the real-time heat transfer coefficient (h) of the heat exchange unit. When the absolute value of the deviation |e|>10℃ and the flue gas flow rate v>[V1]m 3 / s (determined by the rated flow of the equipment), Kp=0.5+0.05×(|e|-10)×(v-[V1]) / [ΔV]; when |e|≤10℃, Kp=0.5-0.03×(10-|e|), ensuring the balance between fast response and stable control and avoiding overshoot oscillation. This adjustment strategy has been optimized through multi-condition simulation to improve control accuracy and response speed.

[0061] (2) Dynamic adjustment rule of integral coefficient (Ki): Adjust according to the deviation integral value (∫e dt) and the heat capacity of the heat exchange unit (C = m × c, m is the mass of the phase change medium, c is the specific heat capacity) and the system time constant (τ = L × h / (v × ρ × Cp), L is the number of heat exchange unit layers, ρ is the flue gas density, and Cp is the specific heat capacity of the flue gas). Ki = 0.01 × (∫e dt) / (C × τ), the integral time window is set to [ΔT]s, and Ki is corrected according to the real-time integral value to eliminate the steady-state error and ensure that the outlet temperature is accurate and constant. This rule is derived based on thermal balance and control theory and is adapted to the thermal characteristics of the equipment.

[0062] (3) Differential coefficient (Kd) optimization mechanism: According to the temperature change rate (de / dt) and the flue gas flow rate fluctuation range (±[Δv]m 3 / s) adjustment. Kd=0.1×(de / dt) / (v+[Δv]), enhances the response to temperature mutation, suppresses fluctuations caused by interference, and the coefficient is dynamically optimized according to the flow rate. It is derived from the coupling analysis of thermal flow and fluid mechanics to improve control robustness.

[0063] 2. Heat exchange unit layout parameters:

[0064] (1) Calculation model for the number of layers (L): L = INT[(R-[ΔR]) / (r+[Δr])], where R is the effective radius of the heat exchange space (excluding wall thermal resistance and installation margin), and r is the outer radius of the heat exchange unit. [ΔR] and [Δr] are determined based on engineering experience and heat conduction simulation to ensure compact layout and efficient heat exchange, avoid channel blockage and dead zone heat loss. The model is verified by simulation and experiment to achieve the optimal number of layers.

[0065] (2) Spacing determination: The spacing between heat exchange units on the same layer is determined to be [X1]-[X2] mm according to the flue gas Pr number (Pr = Cp × μ / k, μ is dynamic viscosity, k is thermal conductivity) and Reynolds number (Re = v × d / μ, d is characteristic length). When the Pr number is 0.6-0.8, the spacing is [X1] mm; when the Pr number is 0.8-1.2, the spacing increases linearly to [X2] mm to ensure uniform flue gas flow and enhance convective heat transfer. Based on the correlation optimization of heat and mass transfer theory and experiments, the overall heat transfer performance is improved.

[0066] 3. Control accuracy parameters

[0067] (1) Target range: Determined as [t0]℃-[t1]℃ based on the flue gas composition (SO2, H2O, etc.) dew point temperature model (t_d=f(S,P,φ), S is the mole fraction of the component, P is the pressure, φ is the relative humidity) and the equipment acid dew point corrosion safety margin ([Δt]℃). For example, when the sulfur content is [S1]%, the pressure is [P1]Pa, and the humidity φ=[φ1]%, t_d+[Δt]=t0, t1=t0+5℃ (to prevent low-temperature corrosion and ash accumulation blockage), to ensure the life of the equipment and stable operation. The model is determined through thermodynamic and chemical corrosion research.

[0068] (2) Adjustment accuracy: The adjustment accuracy of the number of heat exchange units is ±1 (determined by the system's minimum operable unit and thermal inertia); the dwell time timing accuracy is ±0.5 seconds (guaranteed by the control system's clock crystal accuracy and timing algorithm optimization), ensuring accurate and reliable control. It has been tested and verified to meet high-precision control requirements, improving system operation quality and energy efficiency.

[0069] The method for accurately controlling flue gas temperature of the present invention has the following advantages:

[0070] 1. Efficient heat exchange and adaptation to operating conditions: The intelligent air preheater uses multi-phase change temperature heat exchange units and precise selection mechanisms to switch the adaptation materials according to the operating conditions, achieving efficient heat exchange under all operating conditions and improving the efficiency of heat energy conversion and storage, such as using paraffin for startup and polymer phase change materials for full load.

[0071] 2. Cost-effectiveness optimization: Flexible selection of multi-phase change materials reduces production and processing costs, reduces energy waste and maintenance expenses caused by unsuitable working conditions of a single material, and independent interchangeable heat exchange units shorten downtime, reduce operation and maintenance costs, and improve equipment utilization and economic benefits.

[0072] 3. The system is reliable and stable: The intelligent temperature control system uses real-time temperature measurement and intelligent regulation to automatically select the heat exchange unit according to temperature changes, reduce human errors, and through algorithm optimization and precise parameter adjustment, ensure system stability, increase operational reliability, extend equipment life, and enhance the ability to adapt to complex working conditions.

[0073] 4. Enhanced flue gas heat exchange: The spherical or elliptical heat exchange unit is optimally designed to increase the contact time and area between the flue gas and the medium. The unit layout is set according to the flue gas flow parameters to enhance convective heat exchange, evenly distribute the airflow, improve heat exchange efficiency, ensure full heat transfer, and enhance the overall heat exchange effect.

[0074] 5. Precise temperature control to prevent damage: Precise temperature control method uses multi-sensor coordination, advanced PID algorithm and dynamic parameter optimization to control the flue gas outlet temperature in a precise range, prevent dew point corrosion and dust accumulation, improve control accuracy, stabilize operating parameters, ensure equipment safety and reliability, and optimize system operation quality and energy efficiency.

[0075] The above is only one embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. An intelligent air preheater, comprising: The heat absorbing space (1) contains a heat exchange unit, which is used to make the heat exchange unit in the heat absorbing space (1) fully contact with the flue gas and absorb the heat energy in the flue gas; The heat exchange space (2) contains a heat exchange unit, which is used to make the heat exchange unit in the heat exchange space (2) fully contact with the air at normal temperature and release the absorbed heat; The heat exchange unit transfer device (3) is used to realize the transfer of the heat exchange unit in the heat absorption space (1) to the heat exchange space (2) and to realize the transfer of the heat exchange unit in the heat exchange space (2) to the heat absorption space (1), so as to form a heat exchange cycle; characterized in that: It also includes temperature monitoring equipment for collecting the temperature of boiler flue gas in real time; The control system is used to select different heat exchange units to participate in the heat exchange cycle according to the received temperature data.

2. The intelligent air preheater according to claim 1, characterized in that: Also includes: A plurality of spare bins (4), each of which stores a heat exchange unit with a different phase change temperature; The heat exchange unit selection device automatically selects the corresponding heat exchange unit to participate in the heat exchange cycle according to the instructions of the control system.

3. The intelligent air preheater according to claim 1, characterized in that: The phase change material encapsulated in the heat exchange unit includes one of the following materials: Paraffin phase change material, phase change temperature is 160℃; Fatty acid phase change material, phase change temperature is 200℃; Salt phase change material, phase change temperature is 240℃, Polymer phase change material, phase change temperature is 280℃.

4. A method for accurately controlling flue gas temperature using the intelligent air preheater according to any one of claims 1 to 3, comprising: Multiple equally spaced anti-interference infrared temperature acquisition devices are longitudinally arranged inside the heat absorption space to collect the temperature of the heat exchange unit at different heights. The heat absorption efficiency of the heat absorption unit is determined by analyzing the temperature gradient at different heights. According to the temperature monitoring results, the control system dynamically adjusts the frequency and residence time of the heat exchange unit. Install pressure, flow rate, temperature and other sensors at the inlet and outlet of the heat absorption space to monitor the flue gas parameters in real time. Use the PID control algorithm to dynamically adjust the number and residence time of the heat exchange units according to the deviation between the set value and the actual value of the flue gas outlet temperature to keep the flue gas outlet temperature within the target range.

5. The method for accurately controlling flue gas temperature of an intelligent air preheater according to claim 3 is characterized in that: The parameter adjustment mechanism of the PID control algorithm is as follows: Proportional coefficient Kp adjustment strategy: Dynamic adjustment based on the current flue gas flow v, inlet temperature t1 and set outlet temperature t_set deviation e = t_set-t0 and the real-time heat transfer coefficient h of the heat exchange unit: when the absolute value of the deviation |e|>10℃ and the flue gas flow v>[V1]m 3 / s, Kp=0.5+0.05×(|e|-10)×(v-[V1]) / [ΔV]; when |e|≤10℃, Kp=0.5-0.03×(10-|e|); Dynamic adjustment rule of integral coefficient Ki: According to the deviation integral value ∫e dt and the heat capacity of the heat exchange unit C = m × c, and the system time constant τ = L × h / (v × ρ × Cp,), Ki = 0.01 × (∫e dt) / (C × τ), the integral time window is set to [ΔT]s, and Ki is corrected according to the real-time integral value to eliminate the steady-state error and ensure that the outlet temperature is accurate and constant. This rule is derived based on thermal balance and control theory and is adapted to the thermal characteristics of the equipment. Among them, m is the mass of the phase change medium, c is the specific heat capacity, L is the number of heat exchange unit layers, ρ is the flue gas density, and Cp is the specific heat capacity of the flue gas; Differential coefficient Kd optimization mechanism: According to the temperature change rate de / dt and the flue gas flow rate fluctuation range ± [Δv]m 3 / s adjustment, Kd=0.1×(de / dt) / (v+[Δv]).

6. The method for accurately controlling flue gas temperature of an intelligent air preheater according to claim 5 is characterized in that: The heat exchange unit layout parameters are set as follows: Calculation model of layer number L: L = INT[(R-[ΔR]) / (r+[Δr])], R is the effective radius of the heat exchange space. After heat conduction simulation and engineering practice verification, the value range of R is [R1] meters to [R2] meters; r is the outer radius of the heat exchange unit, which is determined to be [X] meters according to the design selection; [ΔR] is set to [X] meters based on the equipment manufacturing tolerance and the influence of wall thermal resistance, and [Δr] is set to [X] meters considering the processing accuracy and assembly clearance of the heat exchange unit; Spacing determination: The spacing between heat exchange units on the same layer is determined as [X1]-[X2] mm according to the flue gas Pr number and the Reynolds number. In the Pr number range of 0.6-0.8, the spacing is precisely locked at [X1] mm; when the Pr number rises to the range of 0.8-1.2, the spacing is adjusted to [X2] mm according to the linear increasing rule, where Pr = Cp×μ / k, μ is the dynamic viscosity, k is the thermal conductivity, Re = v×d / μ, d is the characteristic length.

7. The method for accurately controlling flue gas temperature of an intelligent air preheater according to claim 6, characterized in that: The control accuracy parameters are set as follows: Target range: According to the flue gas component dew point temperature model t_d = f(S, P, φ) and the equipment acid dew point corrosion safety margin [Δt] ℃, it is accurately determined as [t0] ℃ - [t1] ℃. Specifically, when the flue gas sulfur content reaches [S1]%, the pressure is [P1] Pa and the humidity φ = [φ1]%, according to the dew point temperature model t_d + [Δt] = t0, and t1 = t0 + 5 ℃, where S is the component mole fraction, P is the pressure, and φ is the relative humidity; Adjustment accuracy: The adjustment accuracy of the number of heat exchange units is strictly controlled within ±1; the timing accuracy of the residence time is ±0.5 seconds.

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