Environment-friendly, energy-saving and efficient flue gas heat exchanger and control method thereof

Abstract

The application provides an environment-friendly, energy-saving and efficient flue gas heat exchanger and a control method thereof, and relates to the technical field of flue gas heat exchangers. The flue gas heat exchanger comprises a heat exchanger body, which comprises a flow guide cylinder having a heat exchange space inside. The flow guide cylinder has a smoke inlet communicating with the heat exchange space at one end in the extending direction of the flow guide cylinder. The heat exchange space has a heat exchange pipe inside, through which a fluid to be heated flows. The smoke inlet is used for conveying high-temperature flue gas to the space between the inner wall of the flow guide cylinder and the outer wall of the heat exchange pipe. A heat storage assembly is arranged outside the heat exchange space and close to the smoke inlet side. The heat storage assembly is used for leading out part of the high-temperature flue gas in the heat exchange space and storing the heat of the led-out part of the high-temperature flue gas. The stored heat can be used for temperature adjustment of the fluid to be heated flowing in the heat exchange pipe. The scheme can greatly improve the precision and controllability of the heating process, help to improve the stability of product quality, and improve the utilization efficiency of energy.

Description

Technical Field

[0001] This application relates to the field of flue gas heat exchanger technology, specifically to an environmentally friendly, energy-saving, and efficient flue gas heat exchanger and its control method. Background Technology

[0002] In traditional industrial production, for processes that require heating objects using high-temperature flue gas, the degree of heating is often controlled by adjusting the amount of flue gas entering the system. However, this method has many problems.

[0003] On the one hand, frequent adjustments to the flue gas intake can affect the stability of the entire flue gas circulation system, potentially leading to pressure fluctuations, uneven airflow, and other issues, which in turn can affect the normal operation of the system.

[0004] On the other hand, when the heat required by the object to be heated is not high, the excess heat is directly discharged with the flue gas, resulting in a large amount of energy waste, which is not in line with the current development trend of energy conservation and emission reduction.

[0005] Therefore, this extensive heating method is difficult to meet production needs. Summary of the Invention

[0006] In view of the above-mentioned defects or deficiencies in the prior art, this application aims to provide an environmentally friendly, energy-saving and efficient flue gas heat exchanger and its control method, so as to provide a heating method for refining the utilization of heated flue gas.

[0007] Firstly, this application proposes an environmentally friendly, energy-saving, and highly efficient flue gas heat exchanger, comprising:

[0008] The heat exchanger body includes a guide tube, which has a heat exchange space inside. One end of the guide tube along its extension direction has a flue gas inlet communicating with the heat exchange space. The heat exchange space has a heat exchange tube, and a fluid to be heated flows inside the heat exchange tube. The flue gas inlet is used to deliver high-temperature flue gas into the heat exchange space and between the inner wall of the guide tube and the outer wall of the heat exchange tube.

[0009] A heat storage component is provided outside the heat exchange space and near the flue gas inlet. The heat storage component is used to export a portion of the high-temperature flue gas in the heat exchange space and store the heat of the exported portion of the high-temperature flue gas. The stored heat can be used to regulate the temperature of the fluid to be heated flowing in the heat exchange tube.

[0010] According to the technical solution provided in the embodiments of this application, the guide tube has a guide port and a clearance port on the side near the flue gas inlet, and the heat exchange tube has a temperature adjustment port coaxially arranged with the clearance port on the side near the flue gas inlet;

[0011] The heat storage component includes:

[0012] A heat storage chamber containing a phase change material, wherein the phase change material stores or releases heat through its phase change.

[0013] The heat storage unit includes a first diversion pipe and a first valve located at the flow guide port. One end of the first diversion pipe is connected to the first inlet of the heat storage chamber, and the other end of the first diversion pipe is connected to the flow guide port. The first valve is used to control the connection / blocking of the flow guide port and the first diversion pipe, as well as the connection ratio.

[0014] The temperature control unit includes a second diversion pipe and a second valve located at the temperature control port. One end of the second diversion pipe is connected to the first outlet of the heat storage chamber, and the other end of the second diversion pipe passes through the clearance and is connected to the temperature control port. The second valve is used to control the connection / blocking between the temperature control port and the second diversion pipe, as well as the connection ratio.

[0015] According to the technical solution provided in the embodiments of this application, the fluid to be heated has a target heat absorption capacity, and the high-temperature flue gas entering through the flue gas inlet has exchangeable heat capacity; when the target heat absorption capacity is greater than the exchangeable heat capacity, the guide port is connected to the first diversion pipe and the temperature control port is blocked from the second diversion pipe; when the target heat absorption capacity is less than the exchangeable heat capacity, the guide port is blocked from the first diversion pipe and the temperature control port is connected to the second diversion pipe.

[0016] According to the technical solution provided in the embodiments of this application, the heat storage cavity includes a plurality of first sub-cavities connected in series along its extension direction, and the phase change temperature of the phase change material in each of the first sub-cavities is different.

[0017] According to the technical solution provided in the embodiments of this application, the phase change temperature of the phase change material in each of the first compartments gradually decreases along the direction that gradually moves away from the guide tube.

[0018] According to the technical solution provided in the embodiments of this application, the other end of the guide tube along its extension direction has a smoke outlet communicating with the heat exchange space, and the smoke outlet is connected to the flue gas treatment device; the heat storage chamber is also connected to an exhaust pipe, and the exhaust pipe is connected to the flue gas treatment device.

[0019] Secondly, this application proposes a control method for an environmentally friendly, energy-saving, and efficient flue gas heat exchanger, used to control the aforementioned environmentally friendly, energy-saving, and efficient flue gas heat exchanger, comprising the following steps:

[0020] Obtain the target absorbed heat of the fluid to be heated during the target production cycle;

[0021] At the start of the target production cycle, at each first preset time interval, the exchangeable heat of the high-temperature flue gas entering through the flue gas inlet is acquired in real time.

[0022] If the exchangeable heat is greater than the target absorbed heat, and the absolute value of the difference between the exchangeable heat and the target absorbed heat is greater than a first preset threshold, the first valve is controlled to open and the second valve is controlled to close, so as to connect the flow guide port with the first diversion pipe and block the temperature control port from the second diversion pipe.

[0023] According to the technical solution provided in the embodiments of this application, the fluid to be heated is preheated air, and the heat exchange tube has an outlet near the flue gas inlet, which is connected to the air inlet of the boiler device.

[0024] The process of obtaining the target absorbed heat of the fluid to be heated within the target production cycle specifically includes the following steps:

[0025] The target total heat of combustion released by fuel combustion in the boiler device within the target production cycle is obtained, as well as the thermal efficiency of the boiler device and the heat ratio of preheated air. The heat ratio of preheated air is the ratio of the heat absorbed by the preheated air to the target total heat of combustion. The preheated air provides a medium for the complete combustion of the fuel.

[0026] The target absorbed heat is obtained based on the target total heat of combustion, the proportion of heat in the preheated air, and the thermal efficiency.

[0027] According to the technical solution provided in the embodiments of this application, the smoke inlet is connected to the exhaust port of the flue gas generating device through a smoke inlet pipe;

[0028] The real-time acquisition of the exchangeable heat of the high-temperature flue gas entering through the flue gas inlet specifically includes the following steps:

[0029] The composition information of the high-temperature flue gas is acquired in real time, and the composition information includes at least the component type and component ratio;

[0030] Based on the component type, the corresponding component specific heat capacity is obtained; based on the component specific heat capacity and component ratio, the flue gas specific heat capacity is obtained.

[0031] The amount and temperature of the high-temperature flue gas entering through the inlet are acquired in real time, and the exchangeable heat of the high-temperature flue gas entering through the inlet is obtained in real time based on the amount, temperature, target outlet temperature, and specific heat capacity of the flue gas; the target outlet temperature is the current ambient temperature.

[0032] According to the technical solution provided in the embodiments of this application, controlling the opening of the first valve specifically includes the following steps:

[0033] The difference between the exchangeable heat and the target absorbed heat, and the quotient of the difference with the exchangeable heat, are used as the difference ratio;

[0034] Based on the difference ratio, a first opening degree is obtained, and the first valve is controlled to open at the first opening degree.

[0035] Compared with existing technologies, the beneficial effects of this application are as follows: By setting up a heat storage component, this application achieves heating of the object to be heated to the target temperature without adjusting the flue gas inlet. When the object requires less heat, the heat storage component can promptly store excess heat from the flue gas, preventing heat waste from being discharged with the flue gas. Conversely, when the object requires more heat but the current flue gas flowing into the inlet does not carry enough heat, the heat storage component can release the stored heat, working together with the flue gas flowing in the guide tube to ensure the object reaches the target temperature. This method greatly improves the precision and controllability of the heating process, contributing to improved product quality stability. Since frequent adjustments to the flue gas inlet are no longer necessary, the stability of the entire flue gas circulation system is significantly improved, reducing pressure fluctuations and uneven airflow caused by changes in flue gas inlet volume. This reduces adverse effects on other related equipment, ensuring the stable operation of the entire production system. Simultaneously, it greatly improves energy utilization efficiency, aligning with the development concept of energy conservation and emission reduction, helping enterprises reduce energy consumption and costs, and contributing to environmental protection. Attached Figure Description

[0036] Figure 1 A schematic diagram of the structure of an environmentally friendly, energy-saving, and efficient flue gas heat exchanger (one heat exchange tube) provided in the embodiments of this application;

[0037] Figure 2 A schematic diagram of the structure of an environmentally friendly, energy-saving, and efficient flue gas heat exchanger (multiple heat exchange tubes) provided in the embodiments of this application;

[0038] Figure 3 The flowchart shows the steps of controlling the valve in the environmentally friendly, energy-saving, and efficient flue gas heat exchanger provided in the embodiments of this application.

[0039] The text labels in the image represent:

[0040] 1. Boiler unit; 2. Heat storage component; 21. Heat storage chamber; 22. First branch pipe; 23. First valve; 24. Second valve; 25. Second branch pipe; 3. Guide tube; 31. Heat exchange space; 32. Flue gas inlet; 4. Heat exchange tube; 41. Heat exchange tube inlet; 42. Heat exchange tube outlet; 43. Main pipe; 44. Branch pipe; 5. Flue gas treatment device. Detailed Implementation

[0041] The present application will now be described in further detail with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and not intended to limit it. Furthermore, it should be noted that, for ease of description, only the parts relevant to the invention are shown in the accompanying drawings.

[0042] It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other. This application will now be described in detail with reference to the accompanying drawings and embodiments.

[0043] Example 1

[0044] As mentioned in the background section, in view of the problems in the prior art, this application proposes an environmentally friendly, energy-saving, and highly efficient flue gas heat exchanger, such as... Figure 1 As shown, it includes:

[0045] The heat exchanger body includes a guide tube 3, which has a heat exchange space 31 inside. One end of the guide tube 3 along its extension direction has a flue gas inlet 32 ​​communicating with the heat exchange space 31. The heat exchange space 31 has a heat exchange tube 4, and a fluid to be heated flows inside the heat exchange tube 4. The flue gas inlet 32 ​​is used to deliver high-temperature flue gas into the heat exchange space 31 and between the inner wall of the guide tube 3 and the outer wall of the heat exchange tube 4.

[0046] Specifically, the guide tube 3 adopts a cylindrical design, and its length is determined according to the actual heat exchange requirements. It is made of high-temperature resistant stainless steel with good thermal conductivity. The flue gas inlet 32 ​​is located at one end of the guide tube 3, and its shape is circular, with a diameter approximately one-third of the diameter of the guide tube 3. It is tightly connected to the guide tube 3 by welding to ensure that the high-temperature flue gas can smoothly enter the heat exchange space 31 without leakage. The heat exchange tube 4 can be a single tube. Figure 1 As shown), there can also be multiple heat exchange tubes 4. When there are multiple heat exchange tubes 4, the heat exchange tube 4 includes several branch tubes 44 and a main tube 43 (as shown) installed near the flue gas inlet 32. Figure 2 As shown, multiple branch pipes 44 are connected to the flue gas inlet 32 ​​via a main pipe 43, meaning one end of the main pipe 43 is connected to the flue gas inlet 32, and the other end is connected to the multiple branch pipes 44. The heat exchange tubes 4 can be made of copper, which has excellent thermal conductivity and can effectively exchange heat from the flue gas to the fluid to be heated. Both ends of the heat exchange tubes 4 extend out of the guide tube 3 and are fixed to the guide tube 3 by welding. One end is the heat exchange tube inlet 41 for the fluid to be heated, and the other end is the heat exchange tube outlet 42 for the fluid to be heated. Both the heat exchange tube inlet 41 and the heat exchange tube outlet 42 are connected to corresponding pipes for transporting the fluid to be heated.

[0047] The heat storage component 2 is located outside the heat exchange space 31 and near the flue gas inlet 32. The heat storage component 2 is used to exhaust a portion of the high-temperature flue gas in the heat exchange space 31 and store the heat of the exhaust portion of the high-temperature flue gas. The stored heat can be used to adjust the temperature of the fluid to be heated flowing in the heat exchange tube 4.

[0048] Furthermore, the guide tube 3 has a guide port and a clearance port on the side near the flue gas inlet 32, and the heat exchange tube 4 has a temperature regulating port coaxially arranged with the clearance port on the side near the flue gas inlet 32.

[0049] The heat storage component 2 includes:

[0050] A heat storage chamber 21 is provided with a phase change material, which stores or releases heat through its phase change.

[0051] The heat storage unit includes a first diversion pipe 22 and a first valve 23 disposed at the flow guide port. One end of the first diversion pipe 22 is connected to the first inlet of the heat storage chamber 21, and the other end of the first diversion pipe 22 is connected to the flow guide port. The first valve 23 is used to control the connection / blocking of the flow guide port and the first diversion pipe 22, as well as the connection ratio.

[0052] The temperature control unit includes a second diversion pipe 25 and a second valve 24 located at the temperature control port. One end of the second diversion pipe 25 is connected to the first outlet of the heat storage chamber 21, and the other end of the second diversion pipe 25 passes through the clearance opening and is connected to the temperature control port. The second valve 24 is used to control the connection / blocking between the temperature control port and the second diversion pipe 25, as well as the connection ratio.

[0053] Specifically, the heat storage chamber 21 is rectangular in shape and made of ceramic material with good heat insulation properties to reduce heat loss. The phase change material can be paraffin wax, which undergoes a phase change under the heat of the high-temperature flue gas, thereby storing heat and releasing it when needed. The first diversion pipe 22 of the heat storage section is a circular pipe made of a high-temperature resistant alloy material. One end of the first diversion pipe 22 is threaded to the first inlet of the heat storage chamber 21 to ensure a tight and airtight connection and prevent heat leakage. The other end of the first diversion pipe 22 is welded to a guide port, which is located below the guide cylinder 3 near the flue gas inlet 32, and its diameter matches that of the first diversion pipe 22. A first valve 23 is installed at the connection between the first diversion pipe 22 and the guide port, and is an electrically adjustable valve that can precisely control the connection / blockage and the connection ratio between the guide port and the first diversion pipe 22. The second diversion pipe 25 of the temperature control section is also a circular pipe, made of the same material as the first diversion pipe 22. One end of the second diversion pipe 25 is connected to the first outlet of the heat storage chamber 21 by a thread, and the other end is welded to the temperature adjustment port on the side of the heat exchange tube 4 near the flue gas inlet 32. The temperature adjustment port is located on the side of the heat exchange tube 4 and its diameter is adapted to the second diversion pipe 25. In order to meet the sealing effect, the first diversion pipe 22 and the second diversion pipe 25 can be integrally formed with the guide tube 3 and the heat exchange tube 4. The second valve 24 is installed at the connection between the second diversion pipe 25 and the temperature adjustment port. It is also an electric regulating valve, which can accurately control the connection / blockage and the connection ratio between the temperature adjustment port and the second diversion pipe 25 according to actual needs, so as to achieve precise temperature adjustment of the fluid to be heated.

[0054] It should be noted that when there is only one heat exchange tube 4, the temperature control port is located on the side of the heat exchange tube 4 near the flue gas inlet 32. When the heat exchange tube 4 includes several branch tubes 44 and a main pipe 43 located near the flue gas inlet 32, the temperature control port is located on the main pipe 43.

[0055] The working principle of this flue gas heat exchanger is as follows: During actual operation, high-temperature flue gas enters the heat exchange space 31 through the inlet 32. Most of the flue gas flows between the inner wall of the guide tube 3 and the outer wall of the heat exchange tube 4, exchanging heat with the fluid to be heated inside the heat exchange tube 4. Simultaneously, according to the system's temperature requirements, the first valve 23 opens to a certain extent, allowing some of the high-temperature flue gas to enter the heat storage chamber 21 through the first diversion pipe 22. The phase change material absorbs the heat from the flue gas and undergoes a phase change to store it. When the temperature of the fluid to be heated needs adjustment, the second valve 24 opens to a corresponding extent, and the heat stored in the heat storage chamber 21 is released into the fluid to be heated inside the heat exchange tube 4 through the second diversion pipe 25 and the temperature adjustment port, thereby achieving precise temperature regulation of the fluid and achieving an environmentally friendly, energy-saving, and highly efficient heat exchange effect.

[0056] In a preferred embodiment, the fluid to be heated has a target heat absorption capacity, and the high-temperature flue gas entering through the flue gas inlet 32 ​​has exchangeable heat capacity; when the target heat absorption capacity is greater than the exchangeable heat capacity, the guide port is connected to the first diversion pipe 22 and the temperature control port is blocked from the second diversion pipe 25; when the target heat absorption capacity is less than the exchangeable heat capacity, the guide port is blocked from the first diversion pipe 22 and the temperature control port is connected to the second diversion pipe 25.

[0057] Specifically, heat monitoring devices are installed in the heat exchanger system, located at the inlet pipe of the fluid to be heated and the inlet pipe 32 of the high-temperature flue gas. These heat monitoring devices can use high-precision thermocouple thermometers and flow meters to calculate the target heat absorption of the fluid to be heated and the exchangeable heat of the high-temperature flue gas by measuring parameters such as the fluid temperature, flow rate, and specific heat capacity. The control system is connected to the heat monitoring devices and the first and second valves 24. When the calculated target heat absorption is greater than the exchangeable heat, the control system sends an opening signal to the first valve 23 to open it by a certain proportion, and simultaneously sends a closing signal to the second valve 24 to ensure that the guide port is connected to the first diversion pipe 22 and the temperature regulating port is blocked from the second diversion pipe 25, allowing some of the high-temperature flue gas to enter the heat storage chamber 21 to store heat to meet subsequent possible heat demands. For example, in a certain process stage of industrial production, the fluid to be heated needs to be rapidly heated to a specific temperature, but the heat from the high-temperature flue gas entering at this time is insufficient to meet the demand, and the system will automatically perform the above operation.

[0058] Conversely, when the heat absorbed by the target is less than the heat that can be exchanged, the control system closes the first valve 23 and opens the second valve 24, blocking the flow port from the first diversion pipe 22 and connecting the temperature regulating port to the second diversion pipe 25, releasing the heat stored in the heat storage chamber 21 into the fluid to be heated, thereby achieving precise temperature control and rational utilization of energy.

[0059] In a preferred embodiment, the heat storage cavity 21 includes a plurality of first sub-cavities connected in series along its extension direction, and the phase change temperature of the phase change material in each of the first sub-cavities is different.

[0060] Specifically, the heat storage chamber 21 is divided into multiple first sub-chambers by multiple partitions arranged along its extension direction. The size of each first sub-chamber is designed according to actual needs; the size of each first sub-chamber can be the same or different. Adjacent partitions are sealed with sealing strips to prevent disordered heat transfer between the sub-chambers. For each first sub-chamber, a phase change material with a different phase change temperature is selected for filling.

[0061] In a preferred embodiment, the phase change temperature of the phase change material in each of the first compartments gradually decreases along a direction that moves away from the guide tube 3.

[0062] Specifically, the first compartment near the flue gas inlet 32 ​​uses a phase change material with a high phase change temperature, such as a composite salt phase change material with a melting point of [G]℃, which can effectively absorb and store a large amount of heat when the high-temperature flue gas first enters. As the flue gas moves further away from the inlet 32, subsequent first compartments use phase change materials with gradually decreasing phase change temperatures, such as other suitable phase change materials with melting points of [H]℃, [I]℃, etc., where G is less than H and less than I. This allows for phased heat storage based on changes in flue gas temperature, improving heat storage efficiency and flexibility in heat utilization. In practical applications, when high-temperature flue gas enters the heat storage chamber 21, it first exchanges heat with the phase change material in the first compartment with the highest phase change temperature. As the flue gas temperature gradually decreases, subsequent first compartments with different temperatures successively play a heat storage role, providing a multi-stage, highly adaptable heat supply for the entire production process.

[0063] In a preferred embodiment, the other end of the guide tube 3 along its extension direction has a smoke outlet communicating with the heat exchange space 31, and the smoke outlet is connected to the flue gas treatment device 5; the heat storage chamber 21 is also connected to an exhaust pipe, and the exhaust pipe is connected to the flue gas treatment device 5.

[0064] Specifically, the flue gas outlet of the guide tube 3 is located at its other end along its extension direction. The flue gas outlet is circular in shape, with a diameter approximately one-quarter of the diameter of the guide tube 3, and is connected to the guide tube 3 by welding. A high-temperature resistant metal pipe is connected to the flue gas outlet, which transports the flue gas to the flue gas treatment device 5. The diameter of the pipe is matched to the flue gas outlet, and the connection is secured with a gasket and flange to ensure no flue gas leakage. An exhaust pipe is connected to the top of the heat storage chamber 21. The exhaust pipe is made of corrosion-resistant plastic or metal. One end of the exhaust pipe is welded to the exhaust port of the heat storage chamber 21 to ensure a tight seal, and the other end is connected to the flue gas treatment inlet of the flue gas treatment device 5, also using a flange connection for easy installation and maintenance. During the operation of the entire heat exchanger system, both the flue gas after heat exchange and the flue gas after heat storage can smoothly enter the flue gas treatment device 5 through the exhaust pipe for further purification to meet environmental protection requirements. For example, in some industrial sectors with strict requirements for exhaust gas emissions, such as the steel and chemical industries, this exhaust gas treatment connection method can effectively reduce the pollution of exhaust gas to the environment, while also ensuring the environmental performance of the entire heat exchanger system.

[0065] Example 2

[0066] Based on Example 1, this example proposes a control method for an environmentally friendly, energy-saving, and efficient flue gas heat exchanger. This method controls the flue gas heat exchanger as described in Example 1 to transfer heat from the high-temperature flue gas to the fluid to be heated (preheated air). The preheated air is used to aid combustion when the boiler unit 1 burns dye. This method improves energy utilization efficiency while meeting environmental protection and energy-saving requirements. Figure 3 As shown, the control method includes the following steps:

[0067] S1. Obtain the target absorbed heat of the fluid to be heated within the target production cycle;

[0068] Furthermore, the fluid to be heated is preheated air, and the heat exchange tube 4 has an air outlet at the end near the flue gas inlet 32, which is connected to the air inlet of the boiler device 1.

[0069] The process of obtaining the target absorbed heat of the fluid to be heated within the target production cycle specifically includes the following steps:

[0070] The target total heat of combustion released by fuel combustion in the boiler device 1 within the target production cycle is obtained, as well as the thermal efficiency and preheating air heat ratio of the boiler device 1. The preheating air heat ratio is the ratio of the heat absorbed by the preheating air to the target total heat of combustion. The preheating air provides a medium for the complete combustion of the fuel.

[0071] It should be noted that the high-temperature flue gas entering the flue gas heat exchanger can be generated by the boiler device 1 mentioned above (which requires the introduction of preheated air), or it can be flue gas generated by other flue gas generating devices and then transported through the flue gas inlet pipe.

[0072] Specifically, before entering the target production cycle, the type of fuel for the target production cycle is determined by checking the boiler operation log. Different fuel types have different calorific values. For example, the calorific value of coal is generally around 20-30 MJ / kg, while the calorific value of natural gas is approximately 35-55 MJ / m³.

[0073] The target absorbed heat is obtained based on the target total heat of combustion, the proportion of heat in the preheated air, and the thermal efficiency.

[0074] Specifically, the target total heat of combustion is obtained by multiplying the calorific value corresponding to the fuel type and the total amount of fuel. Based on the boiler operation log, previous production cycles with the same fuel type, the same initial temperature of preheated air entering boiler unit 1, and the same discharge temperature of preheated air after combustion are found. Reference total heat of combustion and reference absorbed heat of preheated air in these previous production cycles are then obtained (both parameters are recorded in the boiler operation log). Based on the reference total heat of combustion and reference absorbed heat, the preheated air heat ratio for the target production cycle is obtained (reference absorbed heat divided by reference total heat of combustion gives the preheated air heat ratio). The thermal efficiency of boiler unit 1 is related to the service life of the unit, and the thermal efficiency is calculated based on the service life. The formula for calculating the target absorbed heat can be expressed as: Target absorbed heat = Target total heat of combustion × Preheated air heat ratio × Thermal efficiency.

[0075] Specifically, under normal circumstances, a certain fuel type is usually maintained. Therefore, the fuel type for the target production cycle can be obtained by checking the boiler operation log. However, in certain scenarios, such as rising fuel prices, changes in industry policies, or unforeseen circumstances with the original fuel supplier (e.g., natural disasters causing coal mine shutdowns or natural gas pipeline damage), the company may be unable to obtain fuel from the original channels. In such cases, it is necessary to change the original fuel type. Therefore, before the start of the target production cycle, the fuel type for the target production cycle is not yet determined because it differs from the fuel types used in previous production cycles, and thus cannot be obtained by checking the boiler operation log. The following method is proposed to solve this problem.

[0076] Furthermore, obtaining the target total heat released by fuel combustion within the boiler unit 1 during the target production cycle specifically includes the following steps:

[0077] Obtain the fuel type within the target production cycle, and based on the fuel type, obtain the target total calorific value of combustion;

[0078] Obtaining the fuel type within the target production cycle specifically includes the following steps:

[0079] Determine whether the first change condition is met before the start of the target production cycle or during the production process of the previous production cycle. The first change condition includes at least the price increase of the raw material type being greater than the first preset range and the industry policy prohibiting the use of the raw material type.

[0080] If none of the first change conditions are met, the fuel type of the previous production cycle will be used as the fuel type for the target production cycle; if at least one of the first change conditions is met, the fuel type for the target production cycle will be determined based on the current energy price list and industry policies.

[0081] Furthermore, determining the fuel type for the target production cycle based on current energy price lists and industry policies specifically includes the following steps:

[0082] Based on the production cost budget, energy consumption demand and profit target factors of the enterprise of the boiler unit 1, a price evaluation model is established. The input parameters of the price evaluation model include the price of various fuels (obtained from the current energy price list), the expected purchase quantity, and the correlation parameters between fuel and production efficiency (e.g., a certain fuel may make the operating efficiency of the production equipment higher or lower). The output is the expected cost of various fuels within the target production cycle.

[0083] Based on the price assessment model, the expected cost for each fuel type is obtained; and among all fuel types, the fuel type that meets industry policies and has the lowest expected cost is selected as the fuel type for the target production cycle.

[0084] S2. At the start of the target production cycle, at each first preset time interval, the exchangeable heat of the high-temperature flue gas entering through the flue gas inlet 32 ​​is acquired in real time.

[0085] Furthermore, the smoke inlet 32 ​​is connected to the exhaust port of the smoke generating device through a smoke inlet pipe;

[0086] The real-time acquisition of the exchangeable heat of the high-temperature flue gas entering through the flue gas inlet 32 ​​specifically includes the following steps:

[0087] The composition information of the high-temperature flue gas is acquired in real time, and the composition information includes at least the component type and component ratio;

[0088] Specifically, online flue gas composition analysis technologies, such as laser spectroscopy and mass spectrometry, can be introduced into the flue gas inlet duct to achieve real-time and continuous monitoring of flue gas components.

[0089] Based on the component type, the corresponding component specific heat capacity is obtained; based on the component specific heat capacity and component ratio, the flue gas specific heat capacity is obtained.

[0090] Specifically, if the proportions of each component in the high-temperature flue gas are x1, x2, ... xn, where the sum of all proportions is 1, and the specific heat capacities of each component are c1, c2, ... cn, according to the formula... The specific heat capacity of the flue gas was obtained.

[0091] The amount and temperature of the high-temperature flue gas entering through the inlet 32 ​​are acquired in real time, and the exchangeable heat of the high-temperature flue gas entering through the inlet 32 ​​is obtained in real time based on the amount, temperature, target outlet temperature, and specific heat capacity of the flue gas; the target outlet temperature is the current ambient temperature.

[0092] Specifically, according to the formula To obtain exchangeable heat Where m is the inlet smoke volume, T1 is the inlet smoke temperature, and T2 is the target outlet smoke temperature. This refers to the specific heat capacity of the flue gas.

[0093] S3. If the exchangeable heat is greater than the target absorbed heat, and the absolute value of the difference between the exchangeable heat and the target absorbed heat is greater than a first preset threshold, control the first valve 23 to open and the second valve 24 to close, so as to connect the flow guide port with the first diversion pipe 22 and block the temperature control port from the second diversion pipe 25.

[0094] Specifically, when the exchangeable heat is greater than the target absorbable heat, and the absolute value of the difference between the two is greater than a first preset threshold, the control output module of the control system sends an opening signal to the first valve 23 and a closing signal to the second valve 24, causing the first valve 23 to open to a predetermined proportion (this proportion can be intelligently adjusted according to the size of the difference; the larger the difference, the larger the opening proportion, ensuring sufficient heat is stored in the heat storage chamber 21). This achieves the connection between the guide port and the first diversion pipe 22, and the blockage between the temperature regulating port and the second diversion pipe 25. In this way, excess high-temperature flue gas heat will be stored in the heat storage chamber 21 for use when heat is insufficient in subsequent production processes. This achieves efficient heat utilization and precise control, ensuring that the temperature of the fluid to be heated remains stable within a suitable range throughout the entire production process, improving production efficiency and product quality, and also demonstrating the environmental and energy-saving advantages of the heat exchanger.

[0095] Throughout the entire target production cycle, the control system continuously repeats the above steps S2 and S3, monitoring and adjusting the heat distribution of the high-temperature flue gas in real time to adapt to changes in heat demand during the production process, ensuring that the heat exchanger system is always in a highly efficient and stable operating state, and meeting the requirements of environmentally friendly and energy-saving production.

[0096] In a preferred embodiment, controlling the opening of the first valve 23 specifically includes the following steps:

[0097] The difference between the exchangeable heat and the target absorbed heat, and the quotient of the difference with the exchangeable heat, are used as the difference ratio;

[0098] Based on the difference ratio, a first opening degree is obtained, and the first valve 23 is controlled to open at the first opening degree.

[0099] Specifically, the exchangeable heat is Q1, the target absorbed heat is Q0, and the difference ratio is P = (Q1 - Q0) / Q1. For example, at a certain moment, the exchangeable heat is 1000 kJ (this is just an example data; in actual situations, the specific value is obtained using the method described above), and the target absorbed heat is 800 kJ. Then, according to the above formula, the difference ratio is calculated to be 0.2. Based on the difference ratio, the first opening degree is obtained by looking up a table. The table is a mapping relationship table between the difference ratio and the first opening degree. The mapping relationship table includes multiple sets of one-to-one corresponding difference ratios and first opening degrees. For example, the mapping relationship table includes: The first opening is 10%; The first opening is 20%; The first opening is 30%... Continuing with the example of the difference ratio of 0.2 calculated above, by querying the above mapping table, we can obtain the corresponding first opening of 30%.

[0100] This document uses specific examples to illustrate the principles and implementation methods of this application. The descriptions of the above embodiments are only for the purpose of helping to understand the methods and core ideas of this application. The above descriptions are only preferred embodiments of this application. It should be noted that due to the limitations of written expression, while there are objectively infinite specific structures, those skilled in the art can make several improvements, modifications, or changes without departing from the principles of this invention, and can also combine the above technical features in an appropriate manner. These improvements, modifications, changes, or combinations, or the direct application of the inventive concept and technical solution to other situations without modification, should all be considered within the scope of protection of this application.

Claims

1. An environmentally friendly, energy-saving, and highly efficient flue gas heat exchanger, characterized in that, include: The heat exchanger body includes a guide tube (3), which has a heat exchange space (31) inside. One end of the guide tube (3) along its extension direction has a flue gas inlet (32) that communicates with the heat exchange space (31). The heat exchange space (31) has a heat exchange tube (4), and a fluid to be heated flows inside the heat exchange tube (4). The flue gas inlet (32) is used to deliver high-temperature flue gas into the heat exchange space (31), between the inner wall of the guide tube (3) and the outer wall of the heat exchange tube (4). Heat storage component (2), the heat storage component (2) is located outside the heat exchange space (31) and near the flue gas inlet (32). The heat storage component (2) is used to export part of the high temperature flue gas in the heat exchange space (31) and store the heat of the exported part of the high temperature flue gas. The stored heat can be used to adjust the temperature of the fluid to be heated flowing in the heat exchange tube (4). The guide tube (3) has a guide port and a clearance port on the side near the flue gas inlet (32), and the heat exchange tube (4) has a temperature adjustment port coaxially arranged with the clearance port on the side near the flue gas inlet (32). The heat storage component (2) includes: A heat storage chamber (21) is provided with a phase change material, which stores or releases heat through its phase change. The heat storage unit includes a first diversion pipe (22) and a first valve (23) located at the flow port. One end of the first diversion pipe (22) is connected to the first inlet of the heat storage chamber (21), and the other end of the first diversion pipe (22) is connected to the flow port. The first valve (23) is used to control the connection / blocking between the flow port and the first diversion pipe (22) and the connection ratio. The temperature control unit includes a second diversion pipe (25) and a second valve (24) located at the temperature control port. One end of the second diversion pipe (25) is connected to the first outlet of the heat storage chamber (21), and the other end of the second diversion pipe (25) passes through the clearance port and is connected to the temperature control port. The second valve (24) is used to control the connection / blocking between the temperature control port and the second diversion pipe (25) and the connection ratio. The control method for the environmentally friendly, energy-saving, and efficient flue gas heat exchanger includes the following steps: Obtain the target absorbed heat of the fluid to be heated during the target production cycle; At the start of the target production cycle, at each first preset time interval, the exchangeable heat of the high-temperature flue gas entering through the flue gas inlet (32) is acquired in real time. If the exchangeable heat is greater than the target absorbed heat, and the absolute value of the difference between the exchangeable heat and the target absorbed heat is greater than the first preset threshold, the first valve (23) is opened and the second valve (24) is closed, so that the flow port is connected to the first diversion pipe (22) and the temperature regulating port is blocked from the second diversion pipe (25); The smoke inlet (32) is connected to the exhaust port of the flue gas generating device through a smoke inlet pipe; The real-time acquisition of the exchangeable heat of the high-temperature flue gas entering through the flue gas inlet (32) specifically includes the following steps: The composition information of the high-temperature flue gas is acquired in real time, and the composition information includes at least the component type and component ratio; Based on the component type, the corresponding component specific heat capacity is obtained; based on the component specific heat capacity and component ratio, the flue gas specific heat capacity is obtained. The amount and temperature of the high-temperature flue gas entering through the inlet (32) are obtained in real time, and the exchangeable heat of the high-temperature flue gas entering through the inlet (32) is obtained in real time based on the amount of flue gas entering, the flue gas temperature, the target flue gas temperature, and the specific heat capacity of the flue gas; the target flue gas temperature is the current ambient temperature.

2. The environmentally friendly, energy-saving, and efficient flue gas heat exchanger according to claim 1, characterized in that, The fluid to be heated has a target heat absorption capacity, and the high-temperature flue gas entering through the flue gas inlet (32) has exchangeable heat. When the target heat absorption capacity is greater than the exchangeable heat, the guide port is connected to the first diversion pipe (22) and the temperature control port is blocked from the second diversion pipe (25). When the target heat absorption capacity is less than the exchangeable heat, the guide port is blocked from the first diversion pipe (22) and the temperature control port is connected to the second diversion pipe (25).

3. The environmentally friendly, energy-saving, and efficient flue gas heat exchanger according to claim 1, characterized in that, The heat storage chamber (21) includes a plurality of first sub-chambers connected in series along its extension direction, and the phase change temperature of the phase change material in each of the first sub-chambers is different.

4. The environmentally friendly, energy-saving, and efficient flue gas heat exchanger according to claim 3, characterized in that, Along the direction that gradually moves away from the guide tube (3), the phase change temperature of the phase change material in each of the first compartments gradually decreases.

5. The environmentally friendly, energy-saving, and highly efficient flue gas heat exchanger according to claim 1, characterized in that, The guide tube (3) has a smoke outlet at the other end along its extension direction that communicates with the heat exchange space (31), and the smoke outlet is connected to the flue gas treatment device (5); the heat storage chamber (21) is also connected to an exhaust pipe, and the exhaust pipe is connected to the flue gas treatment device (5).

6. The control method for the environmentally friendly, energy-saving, and efficient flue gas heat exchanger according to claim 1, characterized in that, The fluid to be heated is preheated air. The heat exchange tube (4) has an outlet near the flue gas inlet (32), and the outlet is connected to the inlet of the boiler device (1). The process of obtaining the target absorbed heat of the fluid to be heated within the target production cycle specifically includes the following steps: The target total heat of combustion released by fuel combustion in the boiler device (1) within the target production cycle is obtained, as well as the thermal efficiency and preheating air heat ratio of the boiler device (1). The preheating air heat ratio is the ratio of the heat absorbed by the preheating air to the target total heat of combustion. The preheating air provides a medium for the complete combustion of the fuel. The target absorbed heat is obtained based on the target total heat of combustion, the proportion of heat in the preheated air, and the thermal efficiency.

7. The control method for the environmentally friendly, energy-saving, and efficient flue gas heat exchanger according to claim 6, characterized in that, The control of opening the first valve (23) specifically includes the following steps: The difference between the exchangeable heat and the target absorbed heat, and the quotient of the difference with the exchangeable heat, are used as the difference ratio; Based on the difference ratio, a first opening degree is obtained, and the first valve (23) is controlled to open at the first opening degree.

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