Waste heat utilization equipment of boiler and boiler

Abstract

The waste heat utilization equipment comprises a main flue, a bypass outlet and a bypass inlet are formed in the middle side wall of the main flue, a dust removal system is arranged on the main flue, and the bypass inlet is located in front of the dust removal system; an inlet of the bypass flue is connected with the bypass outlet, and an outlet of the bypass flue is connected with the bypass inlet; the heat exchanger is arranged on the bypass flue and connected with a water supply system of the boiler; the baffle device is arranged at an outlet of the bypass flue; the first temperature instrument is arranged on the side wall of the main flue and located between the bypass inlet and the dust removal system; and the controller is electrically connected with the baffle device and the first temperature instrument, and the controller is used for controlling the baffle opening degree of the baffle device based on the detected temperature of the first temperature instrument so that the flue gas temperature at the inlet of the dust removal system can be within a preset first temperature range. The technical problem that the waste heat utilization rate of the boiler is low is solved.

Description

Technical Field

[0001] The present invention belongs to the technical field of waste heat utilization, and in particular relates to a waste heat utilization device of a boiler and a boiler. Background Art

[0002] The boiler's flue is equipped with a dust removal system, which has strict requirements for flue gas temperature. The flue gas temperature at the dust removal system's inlet is generally required to be between 180°C and 130°C. However, in actual production, the flue gas temperature at the dust removal system's inlet is generally 160°C to 170°C, while the dust removal system requires a flue gas temperature of no less than 130°C. As a result, the boiler's waste heat is not fully utilized, resulting in energy waste. In addition, high flue gas temperature has an adverse effect on the resistance of the subsequent flue, the power consumption of the induced draft fan, and the materials used in the desulfurization system. Furthermore, the large amount of heat carried in the flue gas is directly discharged into the air, which has an adverse impact on the atmospheric environment. Therefore, the low utilization rate of boiler waste heat is a technical problem that needs to be urgently addressed. Summary of the Invention

[0003] The embodiment of the present invention provides a boiler waste heat utilization device and a boiler, which solves the technical problem of low waste heat utilization rate of the boiler.

[0004] In a first aspect, an embodiment of the present invention provides a waste heat utilization device for a boiler, comprising: a main flue, wherein the main inlet of the main flue is connected to the furnace of the boiler, a bypass outlet and a bypass inlet are provided at the middle side wall of the main flue, a dust removal system is provided on the main flue, and the bypass inlet is located in front of the dust removal system; a bypass flue, wherein the inlet of the bypass flue is connected to the bypass outlet, and the outlet of the bypass flue is connected to the bypass inlet; a heat exchanger is provided in the bypass flue, and the heat exchanger is connected to the water supply system of the boiler; a baffle device , arranged at the outlet of the bypass flue; a first thermometer, arranged on the side wall of the main flue, and located between the bypass inlet and the dust removal system; a controller, electrically connected to the baffle device and the first thermometer, the controller being used to: obtain the detection temperature of the first thermometer; based on the detection temperature of the first thermometer, control the baffle opening of the baffle device to make the flue gas temperature at the inlet of the dust removal system within a preset first temperature range; wherein, the greater the detection temperature of the first thermometer, the greater the baffle opening of the baffle device.

[0005] In combination with the first aspect of the present invention, in some embodiments, the feed water system includes a condenser, a low-pressure heater connected to the outlet of the condenser, a deaerator connected to the outlet of the low-pressure heater, a boiler feed water pump connected to the outlet of the deaerator, and a high-pressure heater connected to the outlet of the boiler feed water pump; the heat exchanger includes: a feed water heat exchanger, the inlet of the feed water heat exchanger is connected to the outlet of the boiler feed water pump, and the outlet of the feed water heat exchanger is connected to the inlet of the economizer of the boiler.

[0006] In combination with the first aspect of the present invention, in some embodiments, it also includes: a first water pipe, the inlet of the first water pipe is connected to the outlet of the high-pressure heater; a second water pipe, the inlet of the second water pipe is connected to the outlet of the feed water heat exchanger; a third water pipe, the inlet of the third water pipe is connected to the outlet of the first water pipe and the outlet of the second water pipe, and the outlet of the third water pipe is connected to the inlet of the economizer; a first water flow regulating valve is arranged on the water pipe between the feed water heat exchanger and the boiler feed water pump; a second thermometer is arranged on the first water pipe; a third thermometer is arranged on the second water pipe; wherein the controller is electrically connected to the first water flow regulating valve, the second thermometer and the third thermometer.

[0007] In combination with the first aspect of the present invention, in some embodiments, the low-pressure heater includes a first low-pressure heater connected to the outlet of the condenser, and a second low-pressure heater connected to the outlet of the first low-pressure heater; the outlet of the second low-pressure heater is connected to the inlet of the deaerator; the heat exchanger also includes a condensate heat exchanger, the outlet of the condensate heat exchanger is connected to the inlet of the deaerator, and the inlet of the condensate heat exchanger is connected to the outlet of the condenser; the waste heat utilization equipment further includes: a fourth water pipe, the inlet of the fourth water pipe is connected to the outlet of the second low-pressure heater; a fifth water pipe, the inlet of the fifth water pipe is connected to the outlet of the condensate heat exchanger; a sixth water pipe, the inlet of the sixth water pipe is connected to the outlet of the fourth water pipe and the outlet of the fifth water pipe, and the outlet of the sixth water pipe is connected to the inlet of the deaerator; the fourth a thermometer, arranged on the fourth water pipe; a fifth thermometer, arranged on the fifth water pipe; a seventh water pipe, the inlet of the seventh water pipe being connected to the outlet of the condenser, and the first outlet of the seventh water pipe being connected to the inlet of the first low-pressure heater; an eighth water pipe, the inlet of the eighth water pipe being connected to the second outlet of the seventh water pipe; a ninth water pipe, the inlet of the ninth water pipe being connected to the outlet of the first low-pressure heater; a tenth water pipe, the inlet of the tenth water pipe being connected to the outlet of the eighth water pipe and the outlet of the ninth water pipe; an eleventh water pipe, the inlet of the eleventh water pipe being connected to the outlet of the tenth water pipe, and the outlet of the eleventh water pipe being connected to the inlet of the condensate heat exchanger; a first booster variable frequency pump, arranged on the eleventh water pipe; the controller being electrically connected to the first booster variable frequency pump, the fourth thermometer and the fifth thermometer.

[0008] In combination with the first aspect of the present invention, in some embodiments, it also includes: a second water regulating valve, arranged on the eighth water pipe; a sixth thermometer, arranged on the tenth water pipe; and the controller is electrically connected to the second water regulating valve and the sixth thermometer.

[0009] In combination with the first aspect of the present invention, in some embodiments, it also includes: an air preheater, which is arranged on the main flue and located in front of the dust removal system; a desulfurization system, which is arranged on the main flue and located behind the dust removal system; a twelfth water pipe, the inlet of the twelfth water pipe is connected to the outlet of the tenth water pipe; a smoke cooler, which is arranged on the main flue and located between the dust removal system and the desulfurization system, the inlet of the smoke cooler is connected to the outlet of the twelfth water pipe; a thirteenth water pipe, the inlet of the thirteenth water pipe is connected to the outlet of the smoke cooler; a heater, the water inlet of the heater is connected to the first outlet of the thirteenth water pipe, the water outlet of the heater is connected to the inlet of the first low-pressure heater, and the air outlet of the heater is connected to the air inlet of the air preheater.

[0010] In combination with the first aspect of the present invention, in some embodiments, it also includes: a seventh thermometer, arranged on the main flue and located between the flue gas cooler and the desulfurization system; a second booster variable frequency pump, arranged on the twelfth water pipe; the controller is electrically connected to the seventh thermometer and the second booster variable frequency pump.

[0011] In combination with the first aspect of the present invention, in some embodiments, it also includes: a fourteenth water pipe, the inlet of the fourteenth water pipe is connected to the second outlet of the thirteenth water pipe, and the outlet of the fourteenth water pipe is connected to the inlet of the second low-pressure heater; a third water regulating valve is arranged on the fourteenth water pipe; an eighth thermometer is arranged on the air duct between the air outlet of the heater and the air inlet of the air preheater; the controller is electrically connected to the third water regulating valve and the eighth thermometer.

[0012] In combination with the first aspect of the present invention, in some embodiments, it also includes: a denitrification system, which is arranged on the main flue and located in front of the air preheater; wherein the bypass outlet is arranged between the air preheater and the denitrification system, and the bypass inlet is arranged between the air preheater and the dust removal system.

[0013] In a second aspect, an embodiment of the present invention provides a boiler, comprising the waste heat utilization device of the boiler described in any one of the first aspects.

[0014] The one or more technical solutions provided by the embodiments of the present invention achieve at least the following technical effects or advantages:

[0015] An embodiment of the present invention provides a waste heat utilization device for a boiler, comprising: a main flue, wherein the main inlet of the main flue is connected to the furnace of the boiler, a bypass outlet and a bypass inlet are provided at the middle side wall position of the main flue, a dust removal system is provided on the main flue, and the bypass inlet is located in front of the dust removal system; a bypass flue, wherein the inlet of the bypass flue is connected to the bypass outlet, and the outlet of the bypass flue is connected to the bypass inlet; a heat exchanger is provided in the bypass flue, and the heat exchanger is connected to the water supply system of the boiler; a baffle device is provided at the outlet of the bypass flue; a first thermometer is provided on the side wall of the main flue and is located between the bypass inlet and the dust removal system; a controller is electrically connected to the baffle device and the first thermometer, the controller is used to: obtain the detection temperature of the first thermometer; control the baffle opening of the baffle device based on the detection temperature of the first thermometer, so that the flue gas temperature at the inlet of the dust removal system is within a preset first temperature range; wherein, the greater the detection temperature of the first thermometer, the greater the baffle opening of the baffle device. A heat exchanger is provided on the bypass flue, and the heat exchanger is connected to the water supply system, so that the heat of the boiler flue gas can be transferred to the water in the water supply system, thereby improving the waste heat utilization rate of the boiler.

[0016] Furthermore, since the first thermometer can detect the flue gas temperature at the dust removal system's inlet, the controller can control the damper opening of the damper device based on the temperature detected by the first thermometer, so as to keep the flue gas temperature at the dust removal system's inlet within a preset first temperature range, thereby ensuring the dust removal efficiency of the dust removal system. Thus, the beneficial effects of both improving the boiler's waste heat utilization rate and ensuring the dust removal efficiency of the dust removal system are achieved. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following is a brief introduction to the drawings required for use in the description of the embodiments. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0018] Figure 1 Schematic diagram of a waste heat utilization device for a boiler according to an embodiment of the present invention;

[0019] Figure 2 A schematic diagram of more detailed parts of a waste heat utilization device for a boiler according to an embodiment of the present invention;

[0020] Figure 3 Schematic diagram of the control system network architecture in an embodiment of the present invention. DETAILED DESCRIPTION

[0021] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. All other embodiments obtained by ordinary technicians in this field based on the embodiments of the present invention without making any creative efforts shall fall within the scope of protection of the present invention.

[0022] In the present invention, descriptions such as "first" and "second" are for descriptive purposes only and should not be understood as indicating or implying their relative importance or implicitly indicating the number of the technical features indicated. Therefore, features defined as "first" or "second" may explicitly or implicitly include at least one of such features. In addition, the technical solutions of various embodiments may be combined with each other, but this must be based on the fact that they can be implemented by a person of ordinary skill in the art. If the combination of technical solutions is mutually contradictory or cannot be implemented, it should be deemed that such a combination of technical solutions does not exist and is not within the scope of protection claimed by the present invention.

[0023] Figure 1 Schematic diagram of the waste heat utilization device of the boiler in the embodiment of the present invention. Figure 1As shown, an embodiment of the present invention provides a waste heat utilization device for a boiler, comprising: a main flue 10, wherein a main inlet 130 of the main flue 10 is connected to the furnace of the boiler, a bypass outlet 110 and a bypass inlet 120 are provided at the middle side wall of the main flue 10, a dust removal system 60 is provided on the main flue 10, and the bypass inlet 120 is located in front of the dust removal system 60; a bypass flue 20, wherein the inlet of the bypass flue 20 is connected to the bypass outlet 110, and the outlet of the bypass flue 20 is connected to the bypass inlet 120; a heat exchanger 30, which is provided in the bypass flue 20, and the heat exchanger 30 is connected to the water supply system of the boiler. Connect; the baffle device 40 is arranged at the outlet of the bypass flue 20; the first thermometer 50 is arranged on the side wall of the main flue 10, and is located between the bypass inlet 120 and the dust removal system 60; the controller is electrically connected to the baffle device 40 and the first thermometer 50, and the controller is used to: obtain the detection temperature of the first thermometer 50; based on the detection temperature of the first thermometer 50, control the baffle opening of the baffle device 40 to make the flue gas temperature at the inlet of the dust removal system 60 within a preset first temperature range; wherein, the greater the detection temperature of the first thermometer 50, the greater the baffle opening of the baffle device 40.

[0024] It should be noted that the first thermometer 50 can be located on the inside or outside of the sidewall of the main flue 10. The higher the temperature detected by the first thermometer 50, the less heat is removed by the heat exchanger 30 located in the bypass flue 20. In this case, the damper opening of the damper device 40 needs to be increased to increase the gas flow rate in the bypass flue 20, allowing the heat exchanger 30 in the bypass flue 20 to remove more heat, thereby reducing the flue gas temperature at the inlet of the dust removal system 60 to the first temperature range.

[0025] In some embodiments, the feed water system may include a condenser 70, a low-pressure heater 71 connected to the outlet of the condenser 70, a deaerator 72 connected to the outlet of the low-pressure heater 71, a boiler feed water pump 73 connected to the outlet of the deaerator 72, and a high-pressure heater 74 connected to the outlet of the boiler feed water pump 73; the heat exchanger 30 may include: a feed water heat exchanger 310, the inlet of the feed water heat exchanger 310 is connected to the outlet of the boiler feed water pump 73, and the outlet of the feed water heat exchanger 310 is connected to the inlet of the economizer 75 of the boiler.

[0026] refer to Figure 2 As shown, Figure 2 Schematic diagram of more details of the waste heat utilization device of the boiler in the embodiment of the present invention. Among them, the high-pressure heater 74 can be one or more, and the more can be three.

[0027] In some embodiments, the waste heat utilization equipment of the boiler may further include: a first water pipe 76, the inlet of the first water pipe 76 is connected to the outlet of the high-pressure heater 74; a second water pipe 77, the inlet of the second water pipe 77 is connected to the outlet of the feed water heat exchanger 310; a third water pipe 78, the inlet of the third water pipe 78 is connected to the outlet of the first water pipe 76 and the outlet of the second water pipe 77, and the outlet of the third water pipe 78 is connected to the inlet of the economizer 75; a first water flow regulating valve 79, which is arranged on the water pipe between the feed water heat exchanger 310 and the boiler feed water pump 73; a second thermometer 80, which is arranged on the first water pipe 76; a third thermometer 81, which is arranged on the second water pipe 77; wherein the controller is electrically connected to the first water flow regulating valve 79, the second thermometer 80 and the third thermometer 81.

[0028] In some embodiments, the controller is used to: obtain the detection temperature of the second thermometer 80 and the detection temperature of the third thermometer 81; based on the detection temperature of the second thermometer 80 and the detection temperature of the third thermometer 81, control the first water flow regulating valve 79 so that the deviation between the water temperature at the outlet of the high-pressure heater 74 and the water temperature at the outlet of the feed water heat exchanger 310 is less than a preset water temperature deviation threshold; wherein, the greater the detection temperature of the third thermometer 81 is than the detection temperature of the second thermometer 80, the greater the opening of the first water flow regulating valve 79.

[0029] It should be noted that there may be multiple second thermometers 80 and third thermometers 81, for example, three. The temperature detected by the second thermometer 80 may be the median of the temperatures detected by the multiple second thermometers 80, and the temperature detected by the third thermometer 81 may be the median of the temperatures detected by the multiple third thermometers 81. The actuator may be a first water flow regulating valve 79, which is automatically controlled by a PID controller to ensure that the water temperature at the outlet of the high-pressure heater 74 is consistent with the water temperature at the outlet of the feedwater heat exchanger 310.

[0030] It should be noted that the greater the temperature detected by the third thermometer 81 is than the temperature detected by the second thermometer 80, the greater the heat in the bypass flue 20 and the excessive temperature rise of the water in the feedwater heat exchanger 310. In this case, it is necessary to increase the opening of the first water flow regulating valve 79, that is, to increase the water flow in the feedwater heat exchanger 310, and then reduce the water temperature in the feedwater heat exchanger 310 so that the deviation between the water temperature at the outlet of the high-pressure heater 74 and the water temperature at the outlet of the feedwater heat exchanger 310 is less than a preset water temperature deviation threshold. In addition, fluctuations in the water temperature at the inlet of the economizer 75 can cause large fluctuations in the water level in the steam drum and difficulty in water intake, thereby affecting the normal operation of the boiler. Therefore, the embodiment of the present invention controls the water temperature at the outlet of the high-pressure heater 74 to be consistent with the water temperature at the outlet of the feedwater heat exchanger 310, thereby ensuring the stability of the water temperature at the inlet of the economizer 75, thereby ensuring the operational stability of the boiler.

[0031] refer to Figure 2 As shown, when the feed water heat exchanger 310 is added, the water flow direction of the feed water system includes two paths. The first path flows through the condenser 70, the low-pressure heater 71, the deaerator 72, the boiler feed water pump 73, the high-pressure heater 74, the first water pipe 76, the third water pipe 78 and the economizer 75 in sequence; the second path flows through the condenser 70, the low-pressure heater 71, the deaerator 72, the boiler feed water pump 73, the feed water heat exchanger 310, the second water pipe 77, the third water pipe 78 and the economizer 75 in sequence.

[0032] In some embodiments, the low-pressure heater 71 may include a first low-pressure heater 711 connected to the outlet of the condenser 70, a second low-pressure heater 712 connected to the outlet of the first low-pressure heater 711; the outlet of the second low-pressure heater 712 is connected to the inlet of the deaerator 72; the heat exchanger 30 may also include a condensate heat exchanger 320, the outlet of the condensate heat exchanger 320 is connected to the inlet of the deaerator 72, and the inlet of the condensate heat exchanger 320 is connected to the outlet of the condenser 70; the waste heat utilization equipment may also include: a fourth water pipe 82, the inlet of the fourth water pipe 82 is connected to the outlet of the second low-pressure heater 712; a fifth water pipe 83, the inlet of the fifth water pipe 83 is connected to the outlet of the condensate heat exchanger 320; a sixth water pipe 84, the inlet of the sixth water pipe 84 is connected to the outlet of the fourth water pipe 82 and the outlet of the fifth water pipe 83, and the outlet of the sixth water pipe 84 is connected to the inlet of the deaerator 72; a fourth temperature a temperature meter 85 disposed on the fourth water pipe 82; a fifth temperature meter 86 disposed on the fifth water pipe 83; a seventh water pipe 87, the inlet of the seventh water pipe 87 being connected to the outlet of the condenser 70, and the first outlet of the seventh water pipe 87 being connected to the inlet of the first low-pressure heater 711; an eighth water pipe 88, the inlet of the eighth water pipe 88 being connected to the second outlet of the seventh water pipe 87; a ninth water pipe 89, the inlet of the ninth water pipe 89 being connected to the outlet of the first low-pressure heater 711; a tenth water pipe 90, the inlet of the tenth water pipe 90 being connected to the outlet of the eighth water pipe 88 and the outlet of the ninth water pipe 89; an eleventh water pipe 91, the inlet of the eleventh water pipe 91 being connected to the outlet of the tenth water pipe 90, and the outlet of the eleventh water pipe 91 being connected to the inlet of the condensate heat exchanger 320; a first booster variable frequency pump 92 disposed on the eleventh water pipe 91; and a controller being electrically connected to the first booster variable frequency pump 92, the fourth temperature meter 85, and the fifth temperature meter 86.

[0033] refer to Figure 2 As shown, the first low-pressure heater 711 can be one or more, wherein the more can be two.

[0034] In some embodiments, the controller is used to: obtain the detection temperature of the fourth thermometer 85 and the detection temperature of the fifth thermometer 86; based on the detection temperature of the fourth thermometer 85 and the detection temperature of the fifth thermometer 86, control the first booster variable frequency pump 92 so that the deviation between the water temperature at the outlet of the second low-pressure heater 712 and the water temperature at the outlet of the condensate heat exchanger 320 is less than a preset water temperature deviation threshold; wherein, the greater the detection temperature of the fifth thermometer 86 is than the detection temperature of the fourth thermometer 85, the greater the motor frequency of the first booster variable frequency pump 92.

[0035] It should be noted that there may be multiple fourth thermometers 85 and fifth thermometers 86, for example, three. The temperature detected by the fourth thermometer 85 may be the median of the temperatures detected by the multiple fourth thermometers 85, and the temperature detected by the fifth thermometer 86 may be the median of the temperatures detected by the multiple fifth thermometers 86. The flow rate entering the condensate heat exchanger 320 may be regulated by the first booster variable frequency pump 92, and the water temperature at the outlet of the second low-pressure heater 712 may be automatically controlled by a PID controller to be consistent with the water temperature at the outlet of the condensate heat exchanger 320.

[0036] It should be noted that the greater the temperature detected by the fifth thermometer 86 is than the temperature detected by the fourth thermometer 85, the greater the heat in the bypass flue 20 and the excessive temperature rise of the water in the condensate heat exchanger 320. In this case, it is necessary to increase the motor frequency of the first booster variable frequency pump 92, that is, to increase the water flow to the condensate heat exchanger 320 and thereby reduce the water temperature in the condensate heat exchanger 320 so that the deviation between the water temperature at the outlet of the second low-pressure heater 712 and the water temperature at the outlet of the condensate heat exchanger 320 is less than a preset water temperature deviation threshold. In addition, when the water temperature entering the deaerator 72 fluctuates greatly, it will cause instability in the internal pressure and water temperature of the deaerator 72. This instability will cause excessive vibration of the deaerator 72 and abnormal water temperature control. Therefore, the embodiment of the present invention limits the control of the first booster variable frequency pump 92 based on the detection temperature of the fourth thermometer 85 and the detection temperature of the fifth thermometer 86, thereby ensuring the consistency of the water temperature at the outlet of the second low-pressure heater 712 and the water temperature at the outlet of the condensate heat exchanger 320, avoiding fluctuations in the water temperature at the inlet of the deaerator 72, and thus avoiding excessive vibration of the deaerator 72 and abnormal water temperature control, and ultimately achieving the beneficial effect of improving the operating stability of the boiler.

[0037] It should be noted that, when the condensate heat exchanger 320 is added, the water flow direction of the water supply system also includes the following paths: the third path flows through the condenser 70, the seventh water pipe 87, the first low-pressure heater 711, the ninth water pipe 89, the tenth water pipe 90, the eleventh water pipe 91, the condensate heat exchanger 320, the fifth water pipe 83, the sixth water pipe 84, the deaerator 72, the boiler feed water pump 73, the high-pressure heater 74, the first water pipe 76, the third water pipe 78 and the economizer 75 in sequence; the fourth path flows through the condenser 70, the seventh water pipe 87, the eighth water pipe 88, the tenth water pipe 90, the eleventh water pipe 91, the condensate heat exchanger 320, the fifth water pipe 83, the sixth water pipe 84, the deaerator 72, the boiler feed water pump 73, the high-pressure heater 74, the first water pipe 76, the third water pipe 78 and the economizer 75 in sequence.

[0038] In some embodiments, the boiler waste heat utilization device may further include: a second water regulating valve 93, arranged on the eighth water pipe 88; a sixth thermometer 94, arranged on the tenth water pipe 90; and a controller electrically connected to the second water regulating valve 93 and the sixth thermometer 94.

[0039] In some embodiments, the controller is used to: obtain the detection temperature of the sixth thermometer 94; based on the detection temperature of the sixth thermometer 94, control the second water flow regulating valve 93 so that the water temperature of the tenth water pipe 90 is within a preset second temperature range; wherein, the greater the detection temperature of the sixth thermometer 94, the greater the opening of the second water flow regulating valve 93.

[0040] It should be noted that there may be multiple sixth thermometers 94, for example, three, and the detected temperature of the sixth thermometer 94 may be the median of the detected temperatures of the multiple sixth thermometers 94. The second temperature range may be 80°C ± 5°C.

[0041] It should be noted that since the water temperature at the outlet of the condenser 70 is lower than the water temperature at the outlet of the second low-pressure heater 712, if the temperature detected by the sixth thermometer 94 is too high, the water flow at the outlet of the condenser 70 needs to be increased, that is, the opening of the second water flow regulating valve 93 needs to be increased. Furthermore, water temperature fluctuations in the condensate heat exchanger 320 can cause repeated thermal expansion and contraction of components, increasing the risk of wear and leakage of pipes, valves, and other components. Furthermore, frequent temperature fluctuations can also cause aging of the heating element. Therefore, the embodiment of the present invention controls the second water flow regulating valve 93 based on the temperature detected by the sixth thermometer 94 to ensure that the water temperature of the tenth water pipe 90 is within a preset second temperature range. This reduces water temperature fluctuations in the condensate heat exchanger 320, prevents rapid aging, excessive wear, and leakage of components of the condensate heat exchanger 320, and thereby improves the operational stability of the condensate heat exchanger 320.

[0042] In some embodiments, the waste heat utilization equipment of the boiler may further include: an air preheater 95, which is arranged on the main flue 10 and is located in front of the dust removal system 60; a desulfurization system 96, which is arranged on the main flue 10 and is located behind the dust removal system 60; a twelfth water pipe 97, the inlet of the twelfth water pipe 97 is connected to the outlet of the tenth water pipe 90; a smoke cooler 98, which is arranged on the main flue 10 and is located between the dust removal system 60 and the desulfurization system 96, the inlet of the smoke cooler 98 is connected to the outlet of the twelfth water pipe 97; a thirteenth water pipe 99, the inlet of the thirteenth water pipe 99 is connected to the outlet of the smoke cooler 98; a heater 51, the water inlet of the heater 51 is connected to the first outlet of the thirteenth water pipe 99, the water outlet of the heater 51 is connected to the inlet of the first low-pressure heater 711, and the air outlet of the heater 51 is connected to the air inlet of the air preheater 95.

[0043] It should be noted that when the flue gas cooler 98 and the air heater 51 are installed, the flue gas cooler 98 can transfer the heat of the flue gas to the water to obtain heated water. The heated water then flows to the air heater 51 to heat the flue gas to obtain heated gas. The heated gas is further recycled by the air preheater 95. Therefore, the utilization rate of the waste heat of the boiler is improved.

[0044] In some embodiments, the waste heat utilization equipment of the boiler may further include: a seventh thermometer 52, which is arranged on the main flue 10 and located between the flue gas cooler 98 and the desulfurization system 96; a second booster variable frequency pump 53, which is arranged on the twelfth water pipe 97; and a controller electrically connected to the seventh thermometer 52 and the second booster variable frequency pump 53.

[0045] In some embodiments, the controller is used to: obtain the detection temperature of the seventh thermometer 52; based on the detection temperature of the seventh thermometer 52, control the second booster variable frequency pump 53 so that the flue gas temperature at the inlet of the desulfurization system 96 is within a preset third temperature range; wherein, the greater the detection temperature of the seventh thermometer 52, the greater the motor frequency of the second booster variable frequency pump 53.

[0046] It should be noted that there may be multiple seventh thermometers 52, for example, six, and the temperature detected by the seventh thermometer 52 may be the median of the temperatures detected by the multiple seventh thermometers 52. The third temperature range may be a temperature range around 110°C.

[0047] It should be noted that when the flue gas temperature at the inlet of the desulfurization system 96 is too high, the motor frequency of the second booster variable frequency pump 53 can be increased to increase the water volume of the flue gas cooler 98, thereby removing more flue gas heat and lowering the flue gas temperature at the inlet of the desulfurization system 96. It should be noted that by ensuring that the flue gas temperature at the inlet of the desulfurization system 96 is within the preset third temperature range, the stability of the flue gas temperature at the inlet of the desulfurization system 96 is guaranteed, thereby ensuring the operational stability and desulfurization efficiency of the desulfurization system 96.

[0048] In some embodiments, the waste heat utilization equipment of the boiler may further include: a fourteenth water pipe 54, the inlet of the fourteenth water pipe 54 is connected to the second outlet of the thirteenth water pipe 99, and the outlet of the fourteenth water pipe 54 is connected to the inlet of the second low-pressure heater 712; a third water flow regulating valve 55, arranged on the fourteenth water pipe 54; an eighth thermometer 56, arranged on the air duct between the air outlet of the heater 51 and the air inlet of the air preheater 95; and a controller electrically connected to the third water flow regulating valve 55 and the eighth thermometer 56.

[0049] In some embodiments, the controller is used to: obtain the detection temperature of the eighth thermometer 56; based on the detection temperature of the eighth thermometer 56, control the third water regulating valve 55 so that the gas temperature at the air outlet of the heater 51 is within a preset fourth temperature range; wherein, the greater the detection temperature of the eighth thermometer 56, the greater the opening of the third water regulating valve 55.

[0050] It should be noted that there may be multiple eighth thermometers 56, for example, 12, and the temperature detected by the eighth thermometer 56 may be the average value of the temperatures detected by the multiple eighth thermometers 56. The fourth temperature range may be 95±5°C.

[0051] It should be noted that when the gas temperature at the air outlet of the heater 51 is too high, it indicates that the amount of water flowing from the smoke cooler 98 to the heater 51 is too large, and the heat is too high. In this case, it is necessary to increase the opening of the third water flow regulating valve 55, increase the water flow of the fourteenth water pipe 54, and reduce the water flow to the heater 51. This reduces the total heat and, in turn, the gas temperature at the air outlet of the heater 51. Therefore, adjusting the third water flow regulating valve 55 can maintain the stability of the gas temperature at the air outlet of the heater 51, thereby improving the operational stability of the boiler.

[0052] It should be noted that, when the flue gas cooler 98 is added, the water flow of the water supply system can also include the following paths: The fifth path flows sequentially through the condenser 70, the seventh water pipe 87, the eighth water pipe 88, the tenth water pipe 90, the twelfth water pipe 97, the flue gas cooler 98, the thirteenth water pipe 99, the heater 51, and the first low-pressure heater 711. The sixth path flows sequentially through the condenser 70, the seventh water pipe 87, the eighth water pipe 88, the tenth water pipe 90, the twelfth water pipe 97, the flue gas cooler 98, the thirteenth water pipe 99, the fourteenth water pipe 54, and the second low-pressure heater 712.

[0053] In some embodiments, the boiler waste heat utilization equipment may further include: a denitrification system 57, which is arranged on the main flue 10 and located in front of the air preheater 95; wherein the bypass outlet 110 is arranged between the air preheater 95 and the denitrification system 57, and the bypass inlet 120 is arranged between the air preheater 95 and the dust removal system 60.

[0054] In some embodiments, the economizer 75 can be installed on the main flue 10, ahead of the denitrification system 57. An induced draft fan 58 can also be installed between the flue gas cooler 98 and the dust removal system 60. The main outlet 140 of the main flue 10 can be connected to the chimney. The outlet of the air preheater 95 can be connected to the coal pulverizing system and the boiler furnace combustion support system.

[0055] It should be noted that the operating efficiency of coal-fired boilers in my country is low and still lags behind the international advanced level. The energy conservation task is arduous. The boiler of a certain steel plant's self-owned power plant is designed as a subcritical drum boiler, which adopts natural circulation, single intermediate reheating, four-corner tangential combustion, and a single furnace. The boiler burns 0-30% (heat percentage) blast furnace gas and 0-35000Nm 3 / h coke oven gas coal-fired boiler. The flue gas of the boiler can pass through the economizer 75, denitrification system 57, air preheater 95, bag dust removal system 60, induced draft fan 58, desulfurization system 96 from the furnace, and finally be discharged through the chimney to meet the standards; the boiler condensate feed water system can be fed through the condenser 70, condensate pump, condensate polishing system, low-pressure heater 71, deaerator 72, boiler feed water pump 73, high-pressure heater 74, economizer 75, and finally enter the boiler drum. The boiler air preheater 95 can be a Junkers three-compartment rotary regenerative preheater. The basic structure of the air preheater 95 is a giant rotor filled with heat storage elements. By allowing the heat storage elements to alternately pass through the flue and air duct, the waste heat in the flue gas is transferred to the combustion air (primary air and secondary air system), which plays an important role in the thermal energy utilization efficiency of the boiler. With the increasing requirements for environmental protection and the continuous advancement of the ultimate energy efficiency work, it is necessary to combine the existing production processes and existing deficiencies, fully tap the potential for cost reduction and consumption reduction, further improve power generation efficiency, and contribute to cost reduction and efficiency improvement for enterprises; the flue gas dust removal system 60 adopts a full bag type, requiring the normal operating temperature to be controlled not more than 180℃ and not less than 130℃; currently under the normal load of boiler power generation, the temperature of the air preheater 95 entering the bag dust removal system 60 is 160℃~170℃, and the dust removal system 60 requires the flue gas temperature to be not less than 130℃, so the heat of the flue gas is not fully utilized, and the high flue gas temperature also has an adverse effect on the resistance of the subsequent flue, the power consumption of the induced draft fan, and the materials of the desulfurization system 96, and the temperature discharged into the atmosphere is 130℃~140℃, and the flue gas carries a large amount of heat and is directly discharged into the air, which not only causes a lot of energy waste, but also has an adverse effect on the atmospheric environment.

[0056] It should be noted that the embodiment of the present invention can further recycle the waste heat of the flue gas entering the air preheater 95, and reduce the temperature of the flue gas entering the dust collector from the original 160℃~170℃ to 130℃~140℃, ensuring the safe operation of the subsequent dust removal system 60, and the temperature of the flue gas discharged into the atmosphere is reduced from 130℃~140℃ to 110℃, realizing the recycling of the waste heat of the flue gas. In addition, based on the above-mentioned process flow of boiler waste heat utilization, a DCS control system network architecture is designed, and scientific and reasonable control methods and temperature detection schemes are adopted to realize automatic control of the flue gas temperature and the heat exchange medium temperature, ensuring that they are automatically stabilized within the target value range required by the process, and can be safely and effectively integrated and coordinated with the temperature control of the boiler main process system; at the same time, different operating modes are formulated for different operating conditions in different seasons to ensure the safe operation of the boiler system and the optimal effect and maximum benefit. Finally, the above measures can effectively reduce the energy consumption of power generation, further reduce the cost of power generation, and contribute to the cost reduction and efficiency improvement work of the enterprise.

[0057] It should be noted that after exiting feedwater heat exchanger 310, the flue gas enters condensate heat exchanger 320. After heat exchange, the flue gas mixes with the flue gas at the outlet of air preheater 95, reducing its temperature to 130-140°C before entering the dust collector. Condensate at the outlet of condensate heat exchanger 320 is returned to the inlet of deaerator 72 to displace steam extraction from the steam turbine, thereby improving turbine efficiency.

[0058] It should be noted that three monitoring points can be set for the bypass flue gas temperature of air preheater 95. The actuator is the corresponding outlet flue gas adjustment damper door. Based on the characteristics of the damper itself, frequent movement of the damper during the closed-loop adjustment process is avoided. Open-loop control is adopted and the damper instruction is corrected using a broken line function. Based on an ambient temperature (air temperature at the blower inlet) of 20°C, the damper command value and damper command correction value are determined based on the temperature, automatically controlling the mixed flue gas temperature at the dust removal system 60 inlet to reach the target value range. The set value function relationship can be: (300MW, 85%, 270MW, 65%, 240MW, 55%, 210MW, 40%, 180MW, 35%, 150MW, 30%, 130MW, 25%, 100MW, 20%, 75MW, 15%, 60MW, 0%, 0MW, 0%). For example, (300MW, 85%, ambient temperature 0°C, bypass damper command 65%), (300MW, 85%, ambient temperature 30°C, bypass damper command 95%). Among them, 300MW is the power generation load from boiler combustion to the steam turbine generator, 85% is the damper opening, and the others are similar.

[0059] It should be noted that, see Figure 3 As shown, Figure 3This is a schematic diagram of the control system network architecture in an embodiment of the present invention. The DCS control system network architecture diagram of a temperature measurement control system and method based on boiler flue gas waste heat utilization provided by an embodiment of the present invention. The DCS control system uses the I / A of Shanghai Foxboro Process Control Company. In the Series control system, remote control and status monitoring signals for various on-site medium temperature instruments and control actuators (including temperature instruments, electric control valve actuators, and variable-frequency booster pumps) involved in the boiler's waste heat utilization equipment are collected through the I / O signal module FBM and then transmitted via the Fieldbus network to the master module FCP280. The master module is redundant and enables automatic failover. The master module is programmed to perform all on-site control signal analysis, control logic for each medium temperature control system, and output of actuator automatic control commands. The FGC flue gas waste heat utilization control system communicates and shares data with the power plant's DCS control network and other related control systems (MCS, SCS, and ECS) via redundant network switches. This data can also be communicated and shared via a mesh control network. For example, the outlet temperature signals of the high-pressure heater 74 and the low-pressure heater 71 used for automatic control of the feedwater system and condensate temperature are derived from the MCS system, allowing for effective integration and control coordination within the power plant's DCS system. This enables automatic temperature control of various boiler waste heat utilization media and effective integration and control coordination with the main process systems of the boiler and steam turbine, ensuring safe operation of the boiler and steam turbine main units. As components of the entire DCS control system, the FGC flue gas waste heat utilization control system and other control systems (MCS system, SCS system, ECS system, etc.) are connected to the operator station and engineer station via Ethernet, enabling the main control room operators to remotely monitor and modify programs for the flue gas waste heat utilization temperature control system and other related systems.

[0060] It should be noted that the embodiments of the present invention further fully recycle and utilize the waste heat from boiler flue gas, effectively reducing the exhaust temperature of the air preheater 95 while ensuring the required operating temperature of the dust removal system 60. The design of the temperature detection and control scheme for each medium enables automatic control of the feedwater temperature, condensate temperature, air temperature of the heater 51, and flue gas temperature of the boiler waste heat utilization system, achieving the desired control effect. After entering automatic mode operation, the temperatures of all media can be automatically maintained within the design target value range, achieving the effect of automatic coordinated control optimization of the temperatures of each medium. The selection and installation arrangement of the number of temperature measurement points for each medium, including the calculation and selection of automatic closed-loop feedback values, can effectively prevent the normal operation of the automatic mode from being affected by failures of the temperature measurement point instrumentation itself, and even prevent equipment malfunctions from causing the boiler waste heat system to stop operating, thus ensuring the safe and stable operation of the unit boiler and maximizing energy conservation benefits. This achieves effective coordination and integration between the boiler waste heat utilization system and the automatic control system of the boiler's main process system, thereby achieving effective coordination and integration of production operation and monitoring, which is of great significance for improving the labor efficiency of operators and reducing costs and increasing efficiency. Further improving the efficiency of thermal energy utilization and effectively reducing the energy consumption cost of power generation are also of great significance to the company's energy conservation and emission reduction, cost reduction and efficiency improvement work and environmental protection. At the same time, it also ensures the safe operation of the subsequent process induced draft fan and desulfurization system 96.

[0061] It should be noted that the embodiments of the present invention introduce a process flow for recovering waste heat from power plant boilers. Based on the implementation of this process flow, a scheme for determining the number and location of temperature measurement points for each medium, as well as the control feedback value, is designed and formulated. Based on the characteristics of different media and on-site conditions, control valves, frequency converters, and other equipment are used as actuators, and a one-to-one correspondence is established between these and the temperature control of different media, creating conditions for automatic temperature regulation of different media. Based on the characteristics of the flue gas process flow and the baffle itself, frequent baffle movement during closed-loop regulation is avoided. Open-loop control is employed, and a broken-line function relationship is designed and developed. The broken-line function is used to control and modify the baffle instruction, achieving automatic and stable control of the mixed flue gas temperature at the inlet of the dust removal system 60. Based on the characteristics of media such as boiler feed water and condensate, as well as on-site process flows, a corresponding automatic closed-loop control method is designed and developed. Temperature measurement and feedback value schemes are designed for different locations and media. Electric control valve actuators, frequency converters, and other equipment are used as actuators, establishing a one-to-one correspondence, achieving automatic regulation of the corresponding medium temperature. The measured values ​​of the outlet temperatures of the feedwater heat exchanger 310 and the condensate heat exchanger 320 are introduced into the control system as closed-loop control targets. This ensures that the outlet temperatures of the feedwater heat exchanger 310 and the condensate heat exchanger 320 are consistent with those of the high-pressure heater 74 and the low-pressure heater 71, and that these temperatures are automatically controlled and adjusted. Based on the process flow characteristics of the boiler waste heat utilization system and the characteristics of existing DCS control systems, a corresponding boiler waste heat utilization DCS control system was designed. This not only ensures the effective implementation of the principles of automatic temperature control methods for different media, but also ensures effective coordination and integration between the boiler waste heat utilization system and the automatic control system of the boiler turbine main process system, thereby achieving effective coordination and integration of production operation and monitoring. The selection and installation layout design of the number of temperature measurement points for each medium, including the calculation and selection of automatic closed-loop feedback values, effectively prevents the normal operation of the automatic mode from being affected by failures of the temperature measurement point instrumentation itself, and even prevents equipment malfunctions that could cause the boiler waste heat system to shut down, thus ensuring the safe and stable operation of the unit boiler and maximizing energy efficiency. To ensure stable system operation and maximized efficiency throughout the year, different operating modes are designed for different seasons. In the summer, when ambient temperatures are high, condensate at the flue gas cooler outlet is split into two paths: one path goes to the air heater 51 as a heat source to raise the air temperature, and the other path is sent to the inlet of the low-pressure heater 71, displacing the steam extraction from the steam turbine and further improving the efficiency of waste heat recovery from the flue gas. In the winter, when ambient temperatures are low, the heat absorbed by the flue gas cooler is insufficient to reach the required outlet temperature of the air heater 51. Therefore, the heat from the condensate itself is used to heat the air heater 51.

[0062] An embodiment of the present invention provides a waste heat utilization device for a boiler, comprising: a main flue 10, wherein a main inlet 130 of the main flue 10 is connected to a furnace of the boiler; a bypass outlet 110 and a bypass inlet 120 are provided at a middle side wall of the main flue 10; a dust removal system 60 is provided on the main flue 10, and the bypass inlet 120 is located in front of the dust removal system 60; a bypass flue 20, wherein the inlet of the bypass flue 20 is connected to the bypass outlet 110, and the outlet of the bypass flue 20 is connected to the bypass inlet 120; a heat exchanger 30 is provided in the bypass flue 20, and the heat exchanger 30 is connected to the water supply system of the boiler; The baffle device 40 is provided at the outlet of the bypass flue 20; the first thermometer 50 is provided on the side wall of the main flue 10 and is located between the bypass inlet 120 and the dust removal system 60; the controller is electrically connected to the baffle device 40 and the first thermometer 50, and the controller is used to: obtain the detection temperature of the first thermometer 50; based on the detection temperature of the first thermometer 50, control the baffle opening of the baffle device 40 so that the flue gas temperature at the inlet of the dust removal system 60 is within a preset first temperature range; wherein, the greater the detection temperature of the first thermometer 50, the greater the baffle opening of the baffle device 40. A heat exchanger 30 is provided on the bypass flue 20, and the heat exchanger 30 is connected to the water supply system, so that the flue gas heat of the boiler can be transferred to the water in the water supply system, thereby improving the waste heat utilization rate of the boiler. Furthermore, since the first thermometer 50 can detect the flue gas temperature at the inlet of the dust removal system 60, the controller can control the damper opening of the damper device 40 based on the temperature detected by the first thermometer 50, so as to keep the flue gas temperature at the inlet of the dust removal system 60 within a preset first temperature range, thereby ensuring the dust removal efficiency of the dust removal system 60. Therefore, the beneficial effects of both improving the waste heat utilization rate of the boiler and ensuring the dust removal efficiency of the dust removal system 60 are achieved.

[0063] Based on the same inventive concept, an embodiment of the present invention provides a boiler, including the waste heat utilization device of the boiler of any of the above embodiments.

[0064] It should be understood that more implementation details of the boiler in the embodiment of the present invention can be found in the description of the waste heat utilization device of the boiler described above, and will not be repeated here for the sake of brevity.

[0065] The foregoing description is merely an embodiment of the present invention and is not intended to limit the present invention. Those skilled in the art will readily appreciate that various modifications and variations of the present invention are possible. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present invention are intended to be included within the scope of the claims.

Claims

1. A boiler waste heat utilization device, characterized in that: include: A main flue, wherein the main inlet of the main flue is connected to the furnace of the boiler, a bypass outlet and a bypass inlet are provided at the middle side wall of the main flue, a dust removal system is provided on the main flue, and the bypass inlet is located in front of the dust removal system; a bypass flue, wherein the inlet of the bypass flue is connected to the bypass outlet, and the outlet of the bypass flue is connected to the bypass inlet; a heat exchanger, disposed in the bypass flue, the heat exchanger being connected to the water feed system of the boiler; a baffle device, arranged at the outlet of the bypass flue; a first temperature meter, disposed on a side wall of the main flue and located between the bypass inlet and the dust removal system; A controller is electrically connected to the baffle device and the first thermometer, and the controller is used to: obtain the detection temperature of the first thermometer; based on the detection temperature of the first thermometer, control the baffle opening of the baffle device so that the flue gas temperature at the inlet of the dust removal system is within a preset first temperature range; wherein, the greater the detection temperature of the first thermometer, the greater the baffle opening of the baffle device.

2. The waste heat utilization device of the boiler according to claim 1, characterized in that: The feedwater system includes a condenser, a low-pressure heater connected to an outlet of the condenser, a deaerator connected to an outlet of the low-pressure heater, a boiler feedwater pump connected to an outlet of the deaerator, and a high-pressure heater connected to an outlet of the boiler feedwater pump; The heat exchanger comprises: A feedwater heat exchanger, wherein the inlet of the feedwater heat exchanger is connected to the outlet of the boiler feedwater pump, and the outlet of the feedwater heat exchanger is connected to the inlet of the economizer of the boiler.

3. The waste heat utilization device of the boiler according to claim 2, characterized in that: Also includes: a first water pipe, wherein an inlet of the first water pipe is connected to an outlet of the high-pressure heater; a second water pipe, the inlet of the second water pipe being connected to the outlet of the feedwater heat exchanger; a third water pipe, wherein the inlet of the third water pipe is connected to the outlet of the first water pipe and the outlet of the second water pipe, and the outlet of the third water pipe is connected to the inlet of the economizer; a first water flow regulating valve, provided on the water pipe between the feedwater heat exchanger and the boiler feedwater pump; a second temperature meter, disposed on the first water pipe; a third temperature meter, disposed on the second water pipe; Wherein, the controller is electrically connected to the first water regulating valve, the second thermometer and the third thermometer.

4. The boiler waste heat utilization device according to claim 2, characterized in that: The low-pressure heater includes a first low-pressure heater connected to the outlet of the condenser and a second low-pressure heater connected to the outlet of the first low-pressure heater; the outlet of the second low-pressure heater is connected to the inlet of the deaerator; the heat exchanger also includes a condensate heat exchanger, the outlet of the condensate heat exchanger is connected to the inlet of the deaerator, and the inlet of the condensate heat exchanger is connected to the outlet of the condenser; The waste heat utilization equipment further includes: a fourth water pipe, wherein an inlet of the fourth water pipe is connected to an outlet of the second low-pressure heater; a fifth water pipe, wherein the inlet of the fifth water pipe is connected to the outlet of the condensate heat exchanger; a sixth water pipe, wherein the inlet of the sixth water pipe is connected to the outlet of the fourth water pipe and the outlet of the fifth water pipe, and the outlet of the sixth water pipe is connected to the inlet of the deaerator; a fourth temperature meter, disposed on the fourth water pipe; a fifth temperature meter, disposed on the fifth water pipe; a seventh water pipe, wherein an inlet of the seventh water pipe is connected to the outlet of the condenser, and a first outlet of the seventh water pipe is connected to the inlet of the first low-pressure heater; an eighth water pipe, wherein the inlet of the eighth water pipe is connected to the second outlet of the seventh water pipe; a ninth water pipe, wherein the inlet of the ninth water pipe is connected to the outlet of the first low-pressure heater; a tenth water pipe, the inlet of the tenth water pipe being connected to the outlet of the eighth water pipe and the outlet of the ninth water pipe; an eleventh water pipe, the inlet of the eleventh water pipe being connected to the outlet of the tenth water pipe, and the outlet of the eleventh water pipe being connected to the inlet of the condensate heat exchanger; A first booster variable frequency pump is provided on the eleventh water pipe; The controller is electrically connected to the first booster variable frequency pump, the fourth temperature meter, and the fifth temperature meter.

5. The boiler waste heat utilization device according to claim 4, characterized in that: Also includes: a second water flow regulating valve, provided on the eighth water pipe; a sixth thermometer, disposed on the tenth water pipe; The controller is electrically connected to the second water regulating valve and the sixth temperature meter.

6. The boiler waste heat utilization device according to claim 4, characterized in that: Also includes: An air preheater is provided on the main flue and is located in front of the dust removal system; A desulfurization system is provided on the main flue and is located behind the dust removal system; a twelfth water pipe, the inlet of the twelfth water pipe being connected to the outlet of the tenth water pipe; a smoke cooler, provided on the main flue and located between the dust removal system and the desulfurization system, the inlet of the smoke cooler being connected to the outlet of the twelfth water pipe; a thirteenth water pipe, the inlet of the thirteenth water pipe being connected to the outlet of the cigarette cooler; The air heater has its water inlet connected to the first outlet of the thirteenth water pipe, its water outlet connected to the inlet of the first low-pressure heater, and its air outlet connected to the air inlet of the air preheater.

7. The boiler waste heat utilization device according to claim 6, characterized in that: Also includes: a seventh temperature meter, provided on the main flue and located between the flue gas cooler and the desulfurization system; a second booster variable frequency pump, provided on the twelfth water pipe; The controller is electrically connected to the seventh temperature meter and the second booster variable frequency pump.

8. The boiler waste heat utilization device according to claim 6, characterized in that: Also includes: a fourteenth water pipe, the inlet of the fourteenth water pipe being connected to the second outlet of the thirteenth water pipe, and the outlet of the fourteenth water pipe being connected to the inlet of the second low-pressure heater; a third water flow regulating valve, provided on the fourteenth water pipe; an eighth temperature meter, provided on the air duct between the air outlet of the air heater and the air inlet of the air preheater; The controller is electrically connected to the third water regulating valve and the eighth temperature meter.

9. The boiler waste heat utilization device according to claim 6, characterized in that: Also includes: A denitrification system is provided on the main flue and is located in front of the air preheater; Wherein, the bypass outlet is arranged between the air preheater and the denitrification system, and the bypass inlet is arranged between the air preheater and the dust removal system.

10. A boiler, characterized in that: A waste heat utilization device comprising the boiler according to any one of claims 1 to 9.

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