Closed anti-blocking heat exchange element and high heat exchange efficiency optimization control method

Abstract

The invention relates to the field of heat exchange, in particular to a closed anti-blocking heat exchange element and a high heat exchange efficiency optimization control method.The closed anti-blocking heat exchange element comprises an air pre-heater shell, an air pre-heater rotor, a heat exchange element body and a corrugated plate, a closed channel is formed through the special design of the corrugated plate, the heat exchange efficiency is improved, blocking is prevented, and high-temperature flue gas and cold air flow through the specific channel; a flowmeter and a thermometer are used for monitoring temperature and flow, a heat exchange efficiency function is established, the temperature after heat exchange of high-temperature flue gas and cold air is calculated through a heat balance formula, and the temperature and flow range is adjusted according to a heat exchange efficiency calculation formula and conditions until the temperature of the cold air after heat exchange is not higher than that of hot flue gas and the heat exchange efficiency reaches 35%-45%. And finally, the flow temperature of each working medium is controlled by adjusting valves and the like, so that the heat exchange benefit is maximized. The heat exchange efficiency is improved, blockage is prevented, the sealing performance is enhanced, accurate control is achieved, and wide application prospects are achieved.

Description

Technical Field

[0001] The invention relates to the field of heat exchange, and in particular to a closed anti-blocking heat exchange element and a high heat exchange efficiency optimization control method. Background Art

[0002] As environmental protection requirements become increasingly stringent, it is imperative to reduce NOx emission indicators. The Action Plan for Energy Conservation and Emission Reduction Upgrade and Renovation of Coal-fired Power (2014-2020) has clearly put forward action goals: "The emission concentration of atmospheric pollutants from newly built coal-fired generating units in the eastern region will basically reach the emission limit of gas turbine units. In principle, newly built units in the central region will approach or reach the emission limit of gas turbine units. New units in the western region are encouraged to approach or reach the emission limit of gas turbine units. The atmospheric pollutant emission concentration of existing public coal-fired generating units of 300,000 kilowatts and above, self-provided coal-fired generating units of 100,000 kilowatts and above, and other coal-fired generating units with conditions in the eastern region will basically reach the emission limit of gas turbine units after renovation.

[0003] In the prior art, since the diagonal lines of traditional heat exchange elements run through the entire plate, the straight-lined plates are pressed on the diagonal lines, and the plates are in point contact, after long-term operation in a high-temperature environment, fatigue will occur at the contact points, the heat exchange elements will become loose, and the soot-blowing steam will act on the element plates and be dispersed, failing to achieve the purpose of concentrated pressure. The heat exchange elements transfer heat between high-temperature flue gas and air. Due to the initial temperature, flow rate and specific heat capacity of the high-temperature flue gas and air, the heat exchange efficiency is low and resource utilization is not sufficient.

[0004] Therefore, it is necessary to propose a closed anti-blocking heat exchange element and a high heat exchange efficiency optimization control method to solve the above problems. Summary of the invention

[0005] The purpose of the present invention is to provide a closed anti-blocking heat exchange element and a high heat exchange efficiency optimization control method to solve the problem that there is point contact between the plates. After long-term operation in a high-temperature environment, the contact points will become fatigued, the heat exchange elements will become loose, the soot blowing steam will act on the element plates and be dispersed, the purpose of concentrated pressure cannot be achieved, and the initial temperature, flow rate and specific heat capacity of the high-temperature flue gas and air will affect the heat exchange efficiency.

[0006] To achieve the above object, the present invention provides the following technical solutions:

[0007] A closed anti-blocking heat exchange element and a high heat exchange efficiency optimization control method, comprising an air preheater shell, an air preheater rotor, a heat exchange element, and a corrugated plate. A rotating shaft is installed in the air preheater shell, and the air preheater rotor is rotatably installed in the air preheater shell through the rotating shaft. The heat exchange element is in a closed form. There are multiple numbers of the heat exchange element and the corrugated plates. The heat exchange element forms a closed channel by staggering two of the corrugated plates. Two adjacent closed channels are not interconnected. There is line contact between the two corrugated plates. The corrugated plates are provided with planes, oblique lines and straight grooves. The oblique lines on the two corrugated plates on the same heat exchange element are cross-arranged in the same plane, and the waveforms between the corrugated plates are the same. The heat exchange element It is connected to the air preheater rotor, and a fan-shaped sealing plate is installed on the air preheater shell by bolts. The fan-shaped sealing plate fits tightly with the edge of the air preheater rotor. A primary air bin, a secondary air bin and a hot air bin are arranged inside the air preheater rotor, and the air bins are not interconnected. The primary air bin and the secondary air bin are both connected with air ducts, and the hot air bin is connected with a hot air duct. Two air channels are arranged on the air preheater shell, and the two air channels are respectively connected with the primary air bin and the secondary air bin. A flue gas channel is arranged on the air preheater shell, and the flue gas channel is connected with the hot air bin. A gas flow meter and a thermal resistance thermometer are arranged on the air duct and the hot air duct, and a thermal resistance thermometer is arranged on the air channel and the flue gas channel.

[0008] Preferably, S1: high-temperature flue gas enters the hot air chamber (11) through the hot air pipe (13), and the gas flow meter (16) and the thermal resistance thermometer (17) respectively monitor and record the initial temperature and flue gas flow rate of the high-temperature flue gas per unit time, and the temperature is averaged;

[0009] S2: The primary cold air and the secondary cold air enter the primary air bin (9) and the secondary air bin (10) respectively through the air duct (12). In the same unit time, the gas flow meter (16) and the thermal resistance thermometer (17) respectively monitor and record the initial temperature and air flow of the primary cold air and the secondary cold air, and the average temperature is taken;

[0010] S3: After heat exchange, the high-temperature flue gas is discharged through the flue gas channel (15), and the resistance thermometer (17) monitors and records the temperature of the high-temperature flue gas per unit time, and the temperature is averaged;

[0011] S4: After heat exchange, the primary cold air and the secondary cold air are discharged through the corresponding air channel (14), and the thermal resistance thermometer (17) monitors and records the temperature of the primary cold air and the secondary cold air per unit time, and the average temperature is taken;

[0012] S5: Based on the two recorded data of the thermal resistance thermometer (17) before and after the heat exchange and the recorded data of the gas flow meter (16), the temperature change data and the flue gas flow data of the high-temperature flue gas before and after the heat exchange are obtained, and the temperature change data and the air flow data of the primary cold air and the secondary cold air after the heat exchange are also obtained, and the heat loss in the heat exchange process is eliminated to establish a heat exchange efficiency function;

[0013] S6: According to the heat exchange efficiency function, under the condition that the temperature of the primary cold air and the secondary cold air after heat exchange is not higher than the temperature of the high-temperature flue gas after heat exchange and the heat exchange efficiency reaches 35%-45%, the initial average temperature and initial flue gas flow range of the high-temperature flue gas per unit time and the initial average temperature and initial air flow range of the primary cold air and the secondary cold air are calculated so that the heat exchange efficiency is in the range of 35%-45%. According to the calculation results, the initial temperature and initial flue gas flow of the high-temperature flue gas entering the hot air bin (11) and the initial average temperature and initial air flow of the primary cold air and the secondary cold air are controlled and adjusted to ensure the maximum heat exchange efficiency.

[0014] Preferably, the data recorded by the gas flow meter (16) and the thermal resistance thermometer (17) before and after the heat exchange are used to obtain the temperature difference of the high-temperature flue gas before and after the heat exchange and the temperature difference before and after the primary cold air and the secondary cold air. The heat transfer function is calculated by combining the data. Assuming that the initial temperature of the high-temperature flue gas is T hi , high temperature flue gas temperature after heat exchange T hf , flue gas flow Q m , the constant pressure specific heat capacity of flue gas C pg , the initial temperature of the cold air is T ci1 , the first cold air temperature after heat exchange is T cf1 , the air flow rate of the primary cooling air is Q a1 , the constant pressure specific heat capacity of primary cold air C pa1 , secondary cold air initial temperature T ci2 , secondary cold air temperature after heat exchange T cf2 , air flow rate Q of secondary cooling air a2 , constant pressure specific heat capacity Q of secondary cooling air pa2 , heat transfer efficiency η, the heat transfer calculation formula is as follows:

[0015]

[0016] Where t is time, Q out is the heat released by high temperature flue gas, Q in1 is the heat absorbed by the primary cooling air, Q in2 The heat absorbed by the secondary cooling air.

[0017] Preferably, according to the heat Q released by the high temperature flue gas out , the heat absorbed by the primary cold air Q in1 And the heat absorbed by the secondary cold air Qin2 , the heat transfer efficiency is calculated according to the following formula:

[0018]

[0019] Preferably, the temperature of the primary cold air and the secondary cold air after heat exchange is not higher than the temperature of the high-temperature flue gas after heat exchange, that is, T cf1 ≤T hf And T cf2 ≤T hf , the heat exchange efficiency reaches 35%-45%, that is, 0.35≤η≤0.45.

[0020] Preferably, the initial temperature of high-temperature flue gas, the initial temperature of primary cold air, and the initial temperature of secondary cold air are assumed to be defined, then T hi =T hi_0 , T ci1 =T ci1_0 , T ci2 =T ci2_0 , because air and flue gas are different substances with different specific heat capacities, it is assumed that the constant pressure specific heat capacity of primary cooling air is C pa1 =C pa1_0 , constant pressure specific heat capacity C of secondary cooling air pa2 =C pa2_0 , constant pressure specific heat capacity of high temperature flue gas C pg =C pg_0 For the temperature after heat exchange, the range of temperature and flow rate when the heat exchange efficiency reaches 35%-45%, assuming that the temperature range of high-temperature flue gas after heat exchange is T hf_min to T hf_max , the flue gas flow range is Q m_min To Q m_max , the temperature range after the cold air heat exchange is T cf1_min to T cf1_max , the primary cooling air flow range is Q a1_min To Q a1_max , the temperature range after secondary cold air heat exchange is T cf2_min to T cf2_max , the secondary cooling air flow range is Q a2_min To Q a2_max .

[0021] Preferably, for each assumed T hf In T hf_min to T hf_max Within range, Q m In Q m_min To Q m_max Within the range, T cf1 In T cf1_min to T cf1_max Within range, Q a1 In Qa1_min To Q a1_max Within the range, T cf2 In T cf2_min to T cf2_max Range and Q a2 In Q a2_min To Q a2_max The combination within the range calculates the temperature T after the cold air heat exchange cf1 , the air flow rate before and after heat exchange remains unchanged. According to the heat balance, Q out =Q in1 +Q in2 , the following heat balance formula is obtained:

[0022]

[0023] It follows that Calculate η according to the heat exchange efficiency calculation formula.

[0024] Preferably, according to the calculation result of heat transfer efficiency η, if the calculation result meets T cf1 ≤T hf And T cf2 ≤T hf And 0.35≤η≤0.45, then the initial temperature and flow range combination of high temperature flue gas, primary cold air, and secondary cold air meets the conditions. If the calculation result does not meet the T cf1 ≤T hf And T cf2 ≤T hf If 0.35≤η≤0.45, adjust the temperature and flow range and repeat the above steps until a range that meets the conditions is found.

[0025] Preferably, based on the found average temperature of the high-temperature flue gas and the range of flue gas flow that meet the conditions, as well as the average temperature and air flow range of the primary and secondary cold air, the initial temperature and initial flue gas flow of the high-temperature flue gas entering the hot air bin, as well as the initial average temperature and initial air flow of the primary and secondary cold air are controlled and adjusted by adjusting valves, fan speeds, etc., to ensure maximum heat exchange efficiency.

[0026] Preferably, the upper heat exchange element at the hot end of the air preheater is made of atmospheric corrosion resistant material, and the lower heat exchange element at the cold end of the air preheater is made of acid corrosion resistant enamel material.

[0027] Technical effects and advantages of the present invention:

[0028] 1. The heat exchange element is closed, with two corrugated plates interlaced to form a closed channel. This design reduces the lateral leakage of heat, making the heat transfer more concentrated and efficient. Adjacent closed channels are not interconnected, ensuring that the heat is transferred in a specific channel, improving the pertinence of heat exchange;

[0029] 2. The plane, diagonal lines and straight grooves on the corrugated plate increase the heat exchange area and provide more contact surfaces for heat transfer. The cross arrangement of diagonal lines in the same plane and the same waveform design between the corrugated plates enhance the turbulence effect of the fluid, promote the heat exchange between the flue gas and the heat exchange element, and between the heat exchange element and the cold air, thereby significantly improving the heat exchange efficiency;

[0030] 3. The present invention makes up for the shortcomings of the traditional heat exchange element with point contact surface on the plate, with a firm structure, high heat exchange efficiency and low maintenance cost;

[0031] 4. This high heat exchange efficiency optimization control method accurately monitors the temperature and flow of each link of the closed anti-blocking heat exchange element, establishes a heat exchange efficiency function and performs heat balance calculations. Under the conditions that the temperature of the cold air after heat exchange is not higher than that of the hot flue gas and the heat exchange efficiency is between 35% and 45%, the temperature and flow range are continuously adjusted. Ultimately, the flow and temperature of each working fluid are accurately controlled by adjusting valves, fan speeds, etc., to ensure maximum heat exchange benefits, improve heat exchange efficiency, prevent blockages, enhance sealing and achieve precise control. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 This is a schematic diagram of the structure of a closed anti-blocking heat exchange element of the present invention.

[0033] Figure 2 It is a schematic diagram of the air preheater shell structure of the present invention.

[0034] Figure 3 It is a schematic diagram of the internal structure of the corrugated plate of the present invention.

[0035] Figure 4 This is a flow chart of the high heat exchange efficiency optimization control method of the present invention.

[0036] In the figure: 1. air preheater shell; 2. air preheater rotor; 3. heat exchange element; 4. corrugated plate; 5. flat surface; 6. twill; 7. straight groove; 8. fan-shaped sealing plate; 9. primary air bin; 10. secondary air bin; 11. hot air bin; 12. air duct; 13. hot air duct; 14. air channel; 15. flue gas channel; 16. gas flow meter; 17. thermal resistance thermometer. DETAILED DESCRIPTION

[0037] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0038] The present invention provides Figure 1-Figure 3 A closed anti-blocking heat exchange element shown in the figure includes an air preheater shell 1, an air preheater rotor 2, a heat exchange element 3, and a corrugated plate 4. A rotating shaft is installed in the air preheater shell 1, and the air preheater rotor 2 is rotatably installed in the air preheater shell 1 through the rotating shaft. The composition form of the heat exchange element 3 is closed, and the number of heat exchange elements 3 and corrugated plates 4 is multiple. The heat exchange element 3 forms a closed channel by staggering two corrugated plates 4. The two adjacent closed channels are not interconnected. There is a line contact between the two corrugated plates 4. The corrugated plates 4 are provided with a plane 5, a diagonal pattern 6 and a straight groove 7. The diagonal patterns 6 on the two corrugated plates 4 on the same heat exchange element 3 are cross-arranged in the same plane, and the waveforms between the corrugated plates 4 are the same. The heat exchange element 3 is connected to the air preheater rotor 2, and the air preheater shell 1 is provided with a flat surface ... A fan-shaped sealing plate 8 is installed by bolts, and the fan-shaped sealing plate 8 is tightly fitted with the edge of the air preheater rotor 2. A primary air bin 9, a secondary air bin 10 and a hot air bin 11 are arranged inside the air preheater rotor 2, and the air bins are not interconnected. The primary air bin 9 and the secondary air bin 10 are both connected with air ducts 12, and the hot air bin 11 is connected with a hot air duct 13. Two air channels 14 are arranged on the air preheater shell 1, and the two air channels 14 are respectively connected with the primary air bin 9 and the secondary air bin 10. A flue gas channel 15 is arranged on the air preheater shell 1, and the flue gas channel 15 is connected with the hot air bin 11. A gas flow meter 16 and a thermal resistance thermometer 17 are arranged on the air duct 12 and the hot air duct 13, and a thermal resistance thermometer 17 is arranged on the air channel 14 and the flue gas channel 15;

[0039] In this embodiment, the high-temperature flue gas enters the hot air bin 11 through the hot air pipe 13, and the gas flow meter 16 and the thermal resistance thermometer 17 on the hot air pipe 13 monitor and record the temperature and flue gas flow of the high-temperature flue gas per unit time. The primary cold air and the secondary cold air enter the primary air bin 9 and the secondary air bin 10 respectively through the air pipe 12. In the same unit time, the gas flow meter 16 and the thermal resistance thermometer 17 on the air pipe 12 respectively monitor and record the temperature and air flow of the primary cold air and the secondary cold air. As the air preheater rotor 2 rotates, the heat exchange element 3 connected to the rotor alternately passes through the hot air bin 11 and the air bin 10. Channel 14, when the heat exchange element 3 is in the hot air bin 11, the high-temperature flue gas contacts the heat exchange element 3, and the heat is transferred to the heat exchange element 3 through the corrugated plate 4 of the heat exchange element 3. After heat exchange, the thermal resistance thermometer 17 on the flue gas channel 15 monitors and records the temperature of the high-temperature flue gas per unit time, and the thermal resistance thermometer 17 on the air channel 14 monitors and records the temperature of the primary cold air and the secondary cold air per unit time. The plane 5, the twill 6 and the straight groove 7 on the corrugated plate 4 increase the heat exchange area. At the same time, the cross setting of the twill 6 and the design of the same waveform can enhance the turbulence effect of the flue gas and improve the heat exchange efficiency.

[0040] See also Figure 4 , a high heat exchange efficiency optimization control method, comprising:

[0041] S1: High-temperature flue gas enters the hot air chamber 11 through the hot air pipe 13, and the gas flow meter 16 and the thermal resistance thermometer 17 respectively monitor and record the initial temperature and flue gas flow rate of the high-temperature flue gas per unit time, and the temperature is averaged;

[0042] S2: The primary cold air and the secondary cold air enter the primary air bin 9 and the secondary air bin 10 respectively through the air duct 12. The gas flow meter 16 and the thermal resistance thermometer 17 monitor and record the initial temperature and air flow of the primary cold air and the secondary cold air respectively in the same unit time, and the temperature is averaged;

[0043] S3: After heat exchange, the high-temperature flue gas is discharged through the flue gas channel 15, and the thermal resistance thermometer 17 monitors and records the temperature of the high-temperature flue gas per unit time, and the temperature is averaged;

[0044] S4: After heat exchange, the primary cold air and the secondary cold air are discharged through the corresponding air channel 14, and the thermal resistance thermometer 17 monitors and records the temperature of the primary cold air and the secondary cold air in unit time, and the temperature is averaged;

[0045] S5: Based on the two recorded data of the thermal resistance thermometer 17 before and after the heat exchange and the recorded data of the gas flow meter 16, the temperature change data and the flue gas flow data of the high-temperature flue gas before and after the heat exchange are obtained, and the temperature change data and the air flow data of the primary cold air and the secondary cold air after the heat exchange are also obtained, and the heat loss in the heat exchange process is eliminated to establish a heat exchange efficiency function;

[0046] S6: According to the heat exchange efficiency function, under the condition that the temperature of the primary cold air and the secondary cold air after heat exchange is not higher than the temperature of the high-temperature flue gas after heat exchange and the heat exchange efficiency reaches 35%-45%, the initial average temperature and initial flue gas flow range of the high-temperature flue gas per unit time and the initial average temperature and initial air flow range of the primary cold air and the secondary cold air are calculated so that the heat exchange efficiency is in the range of 35%-45%. According to the calculation results, the initial temperature and initial flue gas flow of the high-temperature flue gas entering the hot air bin 11 and the initial average temperature and initial air flow of the primary cold air and the secondary cold air are controlled and adjusted to ensure the maximum heat exchange efficiency;

[0047] The present invention utilizes the data recorded twice by the thermal resistance thermometer 17 before and after the heat exchange and the data recorded by the gas flowmeter 16 to obtain the temperature change data and the flue gas flow data of the high-temperature flue gas before and after the heat exchange, as well as the temperature change data and the air flow data of the primary cold air and the secondary cold air after the heat exchange. After eliminating the heat loss in the heat exchange process, a heat exchange efficiency function is established. According to the heat exchange efficiency function and the set conditions (the temperature of the primary cold air and the secondary cold air after the heat exchange is not higher than the temperature of the high-temperature flue gas after the heat exchange, and the heat exchange efficiency reaches 35%-45%), the initial average temperature and the initial flue gas flow range of the high-temperature flue gas per unit time when the heat exchange efficiency is within this range, as well as the initial average temperature and the initial air flow range of the primary cold air and the secondary cold air are calculated. Finally, according to the calculation results, the initial temperature and the initial flue gas flow of the high-temperature flue gas entering the hot air bin 11, as well as the initial average temperature and the initial air flow of the primary cold air and the secondary cold air are controlled and adjusted to ensure the maximum heat exchange benefit. By continuously adjusting the input parameters, the heat exchange process is always carried out in the best state, the energy utilization efficiency is improved, and the operating cost is reduced.

[0048] The data recorded by the gas flow meter 16 and the thermal resistance thermometer 17 before and after the heat exchange are used to obtain the temperature difference of the high-temperature flue gas before and after the heat exchange, as well as the temperature difference before and after the primary cold air and the secondary cold air. The heat transfer function is calculated based on the comprehensive data. Assuming that the initial temperature of the high-temperature flue gas is T hi , high temperature flue gas temperature after heat exchange T hf , flue gas flow Q m , the constant pressure specific heat capacity of flue gas C pg , the initial temperature of the cold air is T ci1 , the first cold air temperature after heat exchange is T cf1 , the air flow rate of the primary cooling air is Q a1 , the constant pressure specific heat capacity of primary cold air C pa1 , secondary cold air initial temperature T ci2 , secondary cold air temperature after heat exchange T cf2 , air flow rate Q of secondary cooling air a2 , constant pressure specific heat capacity Q of secondary cooling air pa2 , heat transfer efficiency η, the heat transfer calculation formula is as follows:

[0049]

[0050] Where t is time, Q out is the heat released by high temperature flue gas, Q in1 is the heat absorbed by the primary cooling air, Q in2 The heat absorbed by the secondary cooling air;

[0051] In this embodiment, according to the temperature changes of the high-temperature flue gas and the primary cold air and the secondary cold air before and after the heat exchange, the functional relationship between the respective temperature changes and the air flow rate and the constant-pressure specific heat capacity is calculated to prepare for the calculation of the heat exchange efficiency.

[0052] According to the heat Q released by high temperature flue gas out , the heat absorbed by the primary cold air Q in1 And the heat absorbed by the secondary cold air Q in2 , the heat transfer efficiency is calculated according to the following formula:

[0053] The temperature of the primary cold air and the secondary cold air after heat exchange is not higher than the temperature of the high-temperature flue gas after heat exchange, that is, T cf1 ≤T hf And T cf2 ≤T hf , the heat exchange efficiency reaches 35%-45%, that is, 0.35≤η≤0.45;

[0054] For the initial temperature of high-temperature flue gas, the initial temperature of primary cold air, and the initial temperature of secondary cold air, T hi =T hi_0 , T ci1 =T ci1_0 , T ci2 =T ci2_0 , because air and flue gas are different substances with different specific heat capacities, it is assumed that the constant pressure specific heat capacity of primary cooling air is C pa1 =C pa1_0 , constant pressure specific heat capacity C of secondary cooling air pa2 =C pa2_0 , constant pressure specific heat capacity of high temperature flue gas C pg =C pg_0 For the temperature after heat exchange, the range of temperature and flow rate when the heat exchange efficiency reaches 35%-45%, assuming that the temperature range of high-temperature flue gas after heat exchange is T hf_min to T hf_max , the flue gas flow range is Q m_min To Q m_max , the temperature range after the cold air heat exchange is T cf1_min to T cf1_max , the primary cooling air flow range is Q a1_min To Q a1_max , the temperature range after secondary cold air heat exchange is T cf2_min to T cf2_max , the secondary cooling air flow range is Q a2_min To Q a2_max , for each assumed T hf In T hf_min to T hf_max Within range, Q m In Qm_min To Q m_max Within the range, T cf1 In T cf1_min to T cf1_max Within range, Q a1 In Q a1_min To Q a1_max Within the range, T cf2 In T cf2_min to T cf2_max Range and Q a2 In Q a2_min To Q a2_max The combination within the range calculates the temperature T after the cold air heat exchange cf1 , the air flow rate before and after heat exchange remains unchanged. According to the heat balance, Q out =Q in1 +Q in2 , the following heat balance formula is obtained:

[0055]

[0056] It follows that Calculate η according to the heat exchange efficiency calculation formula;

[0057] According to the calculation results of heat transfer efficiency η, if the calculation results meet T cf1 ≤T hf And T cf2 ≤T hf And 0.35≤η≤0.45, then the initial temperature and flow range combination of high temperature flue gas, primary cold air, and secondary cold air meets the conditions. If the calculation result does not meet the T cf1 ≤T hf And T cf2 ≤T hf If 0.35≤η≤0.45, adjust the temperature and flow range and repeat the above steps until a range that meets the conditions is found;

[0058] In this embodiment, in order to make the heat exchange efficiency reach the target range of 35%-45%, the value ranges of various temperatures and flow rates after heat exchange are set. By analyzing each assumed combination of high-temperature flue gas temperature after heat exchange, flue gas flow rate, temperature after heat exchange of primary cold air, primary cold air flow rate, temperature after heat exchange of secondary cold air and secondary cold air flow rate within a specific range, the core lies in utilizing the heat balance principle, that is, the heat released by high-temperature flue gas is equal to the sum of the heat absorbed by primary cold air and secondary cold air. The temperature of primary cold air after heat exchange is calculated by the heat balance formula. In the calculation process, it is assumed that the air flow rate before and after heat exchange is unchanged. Then, the heat exchange efficiency is calculated according to the heat exchange efficiency calculation formula, and it is judged whether the temperature of primary cold air and secondary cold air after heat exchange is not higher than the temperature of high-temperature flue gas after heat exchange and the heat exchange efficiency is within the range of 35%-45%. If the conditions are not met, the temperature and flow rate ranges are adjusted, and the calculation and judgment are repeated until a combination that meets the conditions is found to achieve optimal control of the heat exchange process, thereby ensuring the maximum heat exchange benefit.

[0059] According to the found average temperature and flue gas flow range of high-temperature flue gas that meet the conditions, as well as the average temperature and air flow range of the primary and secondary cold air, the initial temperature and initial flue gas flow of the high-temperature flue gas entering the hot air bin, as well as the initial average temperature and initial air flow of the primary and secondary cold air are controlled by adjusting valves, fan speeds, etc., to ensure maximum heat exchange efficiency.

[0060] The upper heat exchange element 3 at the hot end of the air preheater is made of atmospheric corrosion resistant material, which plays a role of gas corrosion resistance and prolongs the service life. The lower heat exchange element 3 at the cold end of the air preheater is made of acid corrosion resistant enamel material, which plays a role of acid corrosion resistance and prolongs the service life.

[0061] The above shows and describes the basic principles, main features and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The above embodiments and descriptions only describe the principles of the present invention. The present invention may be subject to various changes and improvements without departing from the spirit and scope of the present invention. These changes and improvements fall within the scope of the present invention. The scope of protection claimed by the present invention is defined by the attached claims and their equivalents.

Claims

1. A closed anti-blocking heat exchange element, comprising an air preheater housing (1), an air preheater rotor (2), a heat exchange element (3), and a corrugated plate (4), characterized in that: A rotating shaft is installed in the air preheater shell (1), and the air preheater rotor (2) is rotatably installed in the air preheater shell (1) via the rotating shaft. The heat exchange element (3) is a closed type. The number of the heat exchange element (3) and the corrugated plate (4) is multiple. The heat exchange element (3) is formed by two corrugated plates (4) interlaced to form a closed channel. Two adjacent closed channels are not interconnected. The two corrugated plates (4) are in line contact. The corrugated plates (4) are provided with a plane (5), a twill (6) and a straight groove (7). The twill (6) on the two corrugated plates (4) on the same heat exchange element (3) are cross-arranged in the same plane, and the waveforms of the corrugated plates (4) are the same. The heat exchange element (3) is connected to the air preheater rotor (2). A fan-shaped sealing plate (8) is installed on the air preheater shell (1) via bolts. The fan-shaped sealing plate (8) is connected to the air preheater shell (1). The edge of the air preheater rotor (2) is tightly fitted, and a primary air bin (9), a secondary air bin (10) and a hot air bin (11) are arranged inside the air preheater rotor (2), and the air bins are not interconnected. The primary air bin (9) and the secondary air bin (10) are both connected to an air duct (12), and the hot air bin (11) is connected to a hot air duct (13). The air preheater housing (1) is provided with two air passages (14), and the two air passages (14) are connected to the hot air passages (13). The channel (14) is respectively connected to the primary air bin (9) and the secondary air bin (10); a flue gas channel (15) is provided on the air preheater housing (1); the flue gas channel (15) is connected to the hot air bin (11); a gas flow meter (16) and a thermal resistance thermometer (17) are provided on the air duct (12) and the hot air duct (13); and a thermal resistance thermometer (17) is provided on the air channel (14) and the flue gas channel (15).

2. A high heat exchange efficiency optimization control method, which is applicable to the closed anti-blocking heat exchange element described in claim 1, characterized in that: include: S1: High-temperature flue gas enters the hot air chamber (11) through the hot air pipe (13), and the gas flow meter (16) and the thermal resistance thermometer (17) respectively monitor and record the initial temperature and flue gas flow rate of the high-temperature flue gas per unit time, and the temperature is averaged; S2: The primary cold air and the secondary cold air enter the primary air bin (9) and the secondary air bin (10) respectively through the air duct (12). In the same unit time, the gas flow meter (16) and the thermal resistance thermometer (17) respectively monitor and record the initial temperature and air flow of the primary cold air and the secondary cold air, and the average temperature is taken; S3: After heat exchange, the high-temperature flue gas is discharged through the flue gas channel (15), and the resistance thermometer (17) monitors and records the temperature of the high-temperature flue gas per unit time, and the temperature is averaged; S4: After heat exchange, the primary cold air and the secondary cold air are discharged through the corresponding air channel (14), and the thermal resistance thermometer (17) monitors and records the temperature of the primary cold air and the secondary cold air per unit time, and the average temperature is taken; S5: Based on the two recorded data of the thermal resistance thermometer (17) before and after the heat exchange and the recorded data of the gas flow meter (16), the temperature change data and the flue gas flow data of the high-temperature flue gas before and after the heat exchange are obtained, and the temperature change data and the air flow data of the primary cold air and the secondary cold air after the heat exchange are also obtained, and the heat loss in the heat exchange process is eliminated to establish a heat exchange efficiency function; S6: According to the heat exchange efficiency function, under the condition that the temperature of the primary cold air and the secondary cold air after heat exchange is not higher than the temperature of the high-temperature flue gas after heat exchange and the heat exchange efficiency reaches 35%-45%, the initial average temperature and initial flue gas flow range of the high-temperature flue gas per unit time and the initial average temperature and initial air flow range of the primary cold air and the secondary cold air are calculated so that the heat exchange efficiency is in the range of 35%-45%. According to the calculation results, the initial temperature and initial flue gas flow of the high-temperature flue gas entering the hot air bin (11) and the initial average temperature and initial air flow of the primary cold air and the secondary cold air are controlled and adjusted to ensure the maximum heat exchange efficiency.

3. A high heat exchange efficiency optimization control method according to claim 2, characterized in that: The data recorded by the gas flow meter (16) and the thermal resistance thermometer (17) before and after the heat exchange are used to obtain the temperature difference of the high-temperature flue gas before and after the heat exchange and the temperature difference before and after the primary cold air and the secondary cold air. The heat transfer function is calculated based on the comprehensive data. Assuming that the initial temperature of the high-temperature flue gas is T hi , high temperature flue gas temperature after heat exchange T hf , flue gas flow Q m , constant pressure specific heat capacity of flue gas C pg , the initial temperature of the cold air is T ci1 , the first cold air temperature after heat exchange is T cf1 , the air flow rate of the primary cooling air is Q a1 , the constant pressure specific heat capacity of primary cold air C pa1 , secondary cold air initial temperature T ci2 , secondary cold air temperature after heat exchange T cf2 , air flow rate Q of secondary cooling air a2 , constant pressure specific heat capacity Q of secondary cooling air pa2 , heat transfer efficiency η, the heat transfer calculation formula is as follows: Where t is time, Q out is the heat released by high temperature flue gas, Q in1 is the heat absorbed by the primary cooling air, Q in2 The heat absorbed by the secondary cooling air.

4. A high heat exchange efficiency optimization control method according to claim 3, characterized in that: According to the heat Q released by high temperature flue gas out , the heat absorbed by the primary cold air Q in1 And the heat absorbed by the secondary cold air Q in2 , the heat transfer efficiency is calculated according to the following formula:

5. A high heat exchange efficiency optimization control method according to claim 2, characterized in that: The temperature of the primary cold air and the secondary cold air after heat exchange is not higher than the temperature of the high-temperature flue gas after heat exchange, that is, T cf1 ≤T hf And T cf2 ≤T hf , the heat exchange efficiency reaches 35%-45%, that is, 0.35≤η≤0.

45.

6. A high heat exchange efficiency optimization control method according to claim 2, characterized in that: For the initial temperature of high-temperature flue gas, the initial temperature of primary cold air, and the initial temperature of secondary cold air, T hi =T hi_0 , T ci1 =T ci1_0 , T ci2 =T ci2_0 , because air and flue gas are different substances with different specific heat capacities, it is assumed that the constant pressure specific heat capacity of primary cooling air is C pa1 =C pa1_0 , constant pressure specific heat capacity C of secondary cooling air pa2 =C pa2_0 , constant pressure specific heat capacity of high temperature flue gas C pg =C pg_0 For the temperature after heat exchange, the range of temperature and flow rate when the heat exchange efficiency reaches 35%-45%, assuming that the temperature range of high-temperature flue gas after heat exchange is T hf_min to T hf_max , the flue gas flow range is Q m_min To Q m_max , the temperature range after the cold air heat exchange is T cf1_min to T cf1_max , the primary cooling air flow range is Q a1_min To Q a1_max , the temperature range after secondary cold air heat exchange is T cf2_min to T cf2_max , the secondary cooling air flow range is Q a2_min To Q a2_max .

7. The high heat exchange efficiency optimization control method according to any one of claims 2 to 6, characterized in that: For each assumed T hf In T hf_min to T hf_max Within range, Q m In Q m_min To Q m_max Within the range, T cf1 In T cf1_min to T cf1_max Within range, Q a1 In Q a1_min To Q a1_max Within the range, T cf2 In T cf2_min to T cf2_max Range and Q a2 In Q a2_min To Q a2_max The combination within the range calculates the temperature T after the cold air heat exchange cf1 , the air flow rate before and after heat exchange remains unchanged. According to the heat balance, Q out =Q in1 +Q in2 , the following heat balance formula is obtained: It follows that Calculate η according to the heat exchange efficiency calculation formula.

8. A high heat exchange efficiency optimization control method according to claim 7, characterized in that: According to the calculation results of heat transfer efficiency η, if the calculation results meet T cf1 ≤T hf And T cf2 ≤T hf And 0.35≤η≤0.45, then the initial temperature and flow range combination of high temperature flue gas, primary cold air, and secondary cold air meets the conditions. If the calculation result does not meet the T cf1 ≤T hf And T cf2 ≤T hf If 0.35≤η≤0.45, adjust the temperature and flow range and repeat the above steps until a range that meets the conditions is found.

9. A high heat exchange efficiency optimization control method according to claim 8, characterized in that: According to the found average temperature and flue gas flow range of high-temperature flue gas that meet the conditions, as well as the average temperature and air flow range of the primary and secondary cold air, the initial temperature and initial flue gas flow of the high-temperature flue gas entering the hot air bin, as well as the initial average temperature and initial air flow of the primary and secondary cold air are controlled by adjusting valves, fan speeds, etc., to ensure maximum heat exchange efficiency.

10. The closed anti-blocking heat exchange element according to claim 1, characterized in that: The upper heat exchange element (3) at the hot end of the air preheater is made of atmospheric corrosion resistant material, and the lower heat exchange element (3) at the cold end of the air preheater is made of acid corrosion resistant enamel material.

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