Waste heat recovery device, control method of waste heat recovery device and boiler

Abstract

The invention relates to the technical field of power station boilers, in particular to a waste heat recovery device, a control method of the waste heat recovery device and a boiler. The waste heat recovery device comprises an air pre-heater and an air heater, the air pre-heater comprises a first detection part, a second detection part and a third detection part, the first detection part is used for detecting the dew point temperature of flue gas at a flue gas inlet, and the second detection part can detect the first pressure value of the flue gas at the flue gas inlet and the second pressure value of the flue gas at a flue gas outlet; the third detection piece is used for detecting the temperature of air introduced into the air duct mechanism; multiple working modes are preset in the air heater, the air heater is in communication connection with the first detection piece, the second detection piece and the third detection piece, different working modes can be selected to heat air introduced into the air duct mechanism, and condensation corrosion and dust deposition blockage of the air preheater are avoided. By applying the waste heat recovery device to the boiler, equipment damage and maintenance cost caused by moisture condensation can be reduced, and the operation efficiency and safety of the boiler are improved.

Description

Technical Field

[0001] The present invention relates to the technical field of power station boilers, and in particular to a waste heat recovery device, a control method for the waste heat recovery device, and a boiler. Background Art

[0002] Air preheater is a waste heat recovery device, also known as air preheater. It is widely used in power station boilers. It uses the heat of flue gas discharged by the boiler to preheat the air entering the boiler for combustion, thereby improving the heat exchange performance of the boiler and reducing energy consumption.

[0003] During the use of the existing waste heat recovery device, due to changes in coal type and ambient wind temperature, the wall temperature at the flue gas outlet is easily reduced to the flue gas acid dew point temperature, and liquid sulfuric acid is easily condensed. Sulfuric acid not only corrodes metals, but also adheres to dust particles in the flue gas, causing them to be deposited in the heat storage element and the flue gas duct mechanism, causing dust accumulation and corrosion on the wall of the flue gas duct mechanism and the heat storage element, which not only reduces the thermal efficiency of the boiler, but may also cause equipment damage and safety problems.

[0004] Therefore, there is an urgent need for a waste heat recovery device, a control method for a waste heat recovery device, and a boiler to solve the above problems. Summary of the invention

[0005] The object of the present invention is to provide a waste heat recovery device, a control method for a waste heat recovery device and a boiler, so as to solve the problems of condensation corrosion and ash accumulation blockage of the air preheater caused by changes in coal type and ambient wind temperature, improve the operating efficiency and safety of the boiler, and reduce equipment damage and maintenance costs caused by condensation.

[0006] In order to achieve the above objectives, the following technical solutions are provided:

[0007] Waste heat recovery device, including:

[0008] An air preheater, comprising a flue gas duct mechanism, an air duct mechanism, a first detection member, a second detection member and a third detection member, wherein the flue gas duct mechanism has a flue gas inlet and a flue gas outlet, the first detection member is configured to detect the dew point temperature of the flue gas at the flue gas inlet, the second detection member can detect a first pressure value of the flue gas at the flue gas inlet and a second pressure value of the flue gas at the flue gas outlet, and the third detection member is configured to detect the temperature of the air passing into the air duct mechanism;

[0009] The air heater is configured to heat the air entering the air duct mechanism. The air heater is preset with a plurality of different working modes. The air heater is communicatively connected with the first detection member, the second detection member and the third detection member, and can select different working modes to heat the air entering the air duct mechanism.

[0010] As an optional solution, the air duct mechanism includes:

[0011] The connecting branch is provided with an air inlet and an air outlet, and the connecting branch is used to connect the air inlet and the air outlet so as to transmit the hot air discharged from the air outlet to the air inlet.

[0012] As an optional solution, the air duct mechanism further includes:

[0013] A valve is arranged on the connecting branch.

[0014] As an optional solution, the air duct mechanism further includes:

[0015] The fourth detection element is configured to detect the temperature of the smoke at the smoke outlet.

[0016] As an optional solution, the waste heat recovery device further includes a control mechanism, and the control mechanism is electrically connected to the air preheater and the air heater respectively.

[0017] As an optional solution, the air heater includes:

[0018] Driving mechanism;

[0019] The heating mechanism is arranged at the output end of the driving mechanism, and the driving mechanism can drive the heating mechanism to rotate so that the heating mechanism is switched between an on state and a off state.

[0020] As an optional solution, the heater further includes a second driving member, and the heating mechanism includes:

[0021] Inner shell;

[0022] A water collecting tank, arranged on the inner shell;

[0023] At least two tube bundles, the water collecting tanks are arranged at both ends of the tube bundles along the axial direction, at least two of the tube bundles are arranged at intervals along the length direction of the water collecting tanks, and the second driving member is used to drive the heat source from one of the water collecting tanks to another of the water collecting tanks via the tube bundles.

[0024] The control method of the waste heat recovery device is completed using the above waste heat recovery device, comprising the following steps:

[0025] When determining whether the temperature of the air at the air inlet detected by the third detection element is greater than a preset value;

[0026] If so, the heater does not need to work;

[0027] If not, when the temperature detected by the third detection element is less than or equal to the dew point temperature detected by the first detection element or when the third detection element detects that the temperature at the air inlet is less than or equal to a preset value, the heater starts to work and heats the air.

[0028] As an optional solution, after the air heater starts to work and heats the air, the following steps are also included:

[0029] Determine whether the difference between the first pressure value and the second pressure value detected by the second detection element is greater than a preset pressure difference;

[0030] If not, the control mechanism controls the working power of the second driving member to decrease, and automatically adjusts the supply amount of the heat source entering the heating mechanism;

[0031] If so, the control mechanism controls the valve to open, and the heated air passes through the air outlet and the connecting branch and enters the heater through the air inlet.

[0032] A boiler comprises the above-mentioned waste heat recovery device.

[0033] Compared with the prior art, the present invention has the following beneficial effects:

[0034] The waste heat recovery device provided by the present invention adjusts the working mode of the air preheater according to the data detected by the first detection component, the second detection component and the third detection component, thereby ensuring that the temperature of the flue gas at the flue gas outlet is reduced to the lowest, while condensation does not occur in the air preheater, and the flue gas exhaust temperature is reduced to the maximum extent to recover the waste heat of the flue gas; the air preheater heats the air entering the air inlet to increase the wall temperature of the air preheater, thereby solving the problems of condensation corrosion and ash accumulation blockage of the air preheater caused by changes in coal type and ambient wind temperature.

[0035] The control method of the waste heat recovery device provided by the present invention determines whether the temperature of the air inlet detected by the third detection component is greater than a preset value, controls whether the heater is turned on, and increases the wall temperature of the air preheater, thereby solving problems such as condensation corrosion and ash accumulation blockage of the air preheater caused by changes in coal type and ambient wind temperature, improves the operating efficiency and safety of the boiler, and reduces equipment damage and maintenance costs caused by condensation.

[0036] The boiler provided by the present invention reduces equipment damage and maintenance costs caused by condensation and improves the operating efficiency and safety of the boiler by applying the above-mentioned waste heat recovery device. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following briefly introduces the drawings required for use in the description of the embodiments of the present invention. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the contents of the embodiments of the present invention and these drawings without paying any creative work.

[0038] Figure 1 A simplified structural diagram of a waste heat recovery device provided in an embodiment of the present invention;

[0039] Figure 2 A schematic diagram of the structure of a heater provided in an embodiment of the present invention;

[0040] Figure 3 When the heater is off Figure 2 Middle AA view;

[0041] Figure 4 When the heater is on Figure 2 Center AA view.

[0042] Reference numerals:

[0043] 100. Waste heat recovery device;

[0044] 10. air preheater; 11. heat storage element; 12. flue gas duct mechanism; 121. flue gas inlet; 122. flue gas outlet; 13. air duct mechanism; 131. air inlet; 132. air outlet; 133. connecting branch; 134. valve; 14. first detection member; 15. second detection member; 16. fourth detection member; 17. third detection member;

[0045] 20. Heater; 21. Outer shell; 22. Driving mechanism; 221. First driving member; 222. Transmission member; 23. Heating mechanism; 231. Inner shell; 232. Water collecting tank; 233. Tube bundle; 234. Pipe assembly; 2341. Support pipe; 2342. Hose; 235. Support member; 24. Second driving member; 25. Heat source inlet; 26. Water outlet; 27. Manual start-stop member;

[0046] 30. Control mechanism. DETAILED DESCRIPTION

[0047] In order to make the above-mentioned purposes, features and advantages of the present application more obvious and easy to understand, the specific implementation methods of the present application are described in detail below in conjunction with the accompanying drawings. In the following description, many specific details are set forth to facilitate a full understanding of the present application. However, the present application can be implemented in many other ways different from those described herein, and those skilled in the art can make similar improvements without violating the connotation of the present application, so the present application is not limited by the specific embodiments disclosed below.

[0048] In the description of the present application, it should be understood that if the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise", "axial", "radial", "circumferential", etc. appear, the orientation or position relationship indicated by these terms is based on the orientation or position relationship shown in the accompanying drawings, which is only for the convenience of describing the present application and simplifying the description, and does not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present application.

[0049] In addition, if the terms "first" or "second" appear, these terms are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include at least one of the features. In the description of this application, if the term "plurality" appears, the meaning of "plurality" is at least two, such as two, three, etc., unless otherwise clearly and specifically defined.

[0050] In this application, unless otherwise clearly specified and limited, if the terms "installed", "connected", "connected", "fixed" and the like appear, these terms should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integrated connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements, unless otherwise clearly defined. For ordinary technicians in this field, the specific meanings of the above terms in this application can be understood according to the specific circumstances.

[0051] In the present application, unless otherwise clearly specified and limited, if there is a description that a first feature is "above" or "below" a second feature, etc., or similar descriptions appear, it may mean that the first and second features are in direct contact, or that the first and second features are in indirect contact through an intermediate medium. Moreover, the first feature being "above", "above" and "above" the second feature may mean that the first feature is directly above or obliquely above the second feature, or simply means that the first feature is higher in level than the second feature. The first feature being "below", "below" and "below" the second feature may mean that the first feature is directly below or obliquely below the second feature, or simply means that the first feature is lower in level than the second feature.

[0052] It should be noted that if an element is referred to as being "fixed to" or "disposed on" another element, it may be directly on the other element or there may be a central element. If an element is considered to be "connected to" another element, it may be directly connected to the other element or there may be a central element at the same time. If any, the terms "vertical", "horizontal", "upper", "lower", "left", "right" and similar expressions used in this application are for illustrative purposes only and do not represent the only implementation method.

[0053] This embodiment provides a boiler for providing a specified quantity and quality of steam to a steam turbine to drive the steam turbine to rotate and realize thermal power generation.

[0054] The boiler includes a furnace body, in which the combustible material burns to generate flue gas, which contains heat. In order to improve boiler efficiency and achieve energy conservation and emission reduction, it is usually necessary to recover the heat in the flue gas. Therefore, the boiler provided in this embodiment also includes a waste heat recovery device 100. Figure 1 As shown, the waste heat recovery device 100 includes an air preheater 10, and the air preheater 10 includes a flue gas duct mechanism 12, an air duct mechanism 13 and a heat storage element 11. The flue gas duct mechanism 12 has a flue gas inlet 121 and a flue gas outlet 122, the air duct mechanism 13 has an air inlet 131 and an air outlet 132, and the heat storage element 11 is arranged inside the flue gas duct mechanism 12 and the air duct mechanism 13 and can rotate relative to the flue gas duct mechanism 12 and the air duct mechanism 13. When the air preheater 10 is in operation, high-temperature flue gas enters the flue gas duct mechanism 12 from the flue gas inlet 121 along the vertical direction from top to bottom from the flue gas at the rear of the furnace body, passes through the heat storage element 11, transfers heat to the heat storage element 11, and is discharged from the flue gas outlet 122. Air enters the air preheater 10 from the air inlet 131 along the vertical direction from bottom to top, and the area of ​​the heat storage element 11 heated by the high-temperature flue gas rotates to the air duct mechanism 13. The heat storage element 11 transfers heat to the air coming in from the air inlet 131, and the heated air is transmitted back to the furnace body through the air outlet 132, thereby increasing the temperature of the air required for the combustion, thereby improving the boiler efficiency.

[0055] During the use of the existing waste heat recovery device 100, due to changes in coal type and ambient wind temperature, the wall temperature at the flue gas outlet 122 is easily reduced to the flue gas acid dew point temperature, and liquid sulfuric acid is easily condensed. Sulfuric acid not only corrodes metals, but also adheres to dust particles in the flue gas, causing them to be deposited in the heat storage element 11 and the flue gas duct mechanism 12, causing dust accumulation and corrosion on the wall of the flue gas duct mechanism 12 and the heat storage element 11, which not only reduces the thermal efficiency of the boiler, but may also cause equipment damage and safety problems.

[0056] In order to solve the above problems, the waste heat recovery device 100 provided in this embodiment also includes a heater 20, which is arranged inside the air duct and is used to heat the air introduced into the air duct mechanism 13 from the air inlet 131. The air preheater 10 includes a first detection component 14, a second detection component 15 and a third detection component 17. The first detection component 14 is configured to detect the dew point temperature of the flue gas at the flue gas inlet 121. The second detection component 15 is provided at the flue gas inlet 121 and the flue gas outlet 122. The second detection component 15 can detect the first pressure value of the flue gas at the flue gas inlet 121 and the second pressure value of the flue gas at the smoke gas outlet 122. The third detection component 17 is used to detect the temperature of the air introduced into the air duct mechanism 13. The heater 20 is preset with a plurality of different working modes. The heater 20 is communicatively connected with the first detection component 14, the second detection component 15 and the third detection component 17, and can select different working modes to heat the air introduced into the air duct mechanism 13. By adjusting the working mode of the air preheater 10 according to the data detected by the first detection member 14, the second detection member 15 and the third detection member 17, it is ensured that the temperature of the flue gas at the flue gas outlet 122 is reduced to the minimum, the air preheater 10 does not condense, and the flue gas exhaust temperature is reduced to the maximum extent to recover the flue gas waste heat; the air preheater 10 heats the air entering the air inlet 131 to increase the wall temperature of the air preheater 10, solve the problems of condensation corrosion and ash accumulation and blockage of the air preheater 10 caused by changes in coal type and ambient wind temperature, improve the operating efficiency and safety of the boiler, and reduce equipment damage and maintenance costs caused by condensation. In addition, during the cold start of the boiler, the heater 20 can increase the ignition air temperature, improve the initial combustion conditions, save start-up oil, and reduce the possibility of unburned oil smoke and oil scale accumulating at the rear of the furnace body to cause secondary combustion.

[0057] Optionally, there are two second detection components 15 , one of which is located at the smoke inlet 121 to detect a first pressure value of the smoke at the smoke inlet 121 , and the other second detection component 15 is located at the smoke outlet 122 to detect a second pressure value of the smoke at the smoke outlet 122 .

[0058] When the third detection component 17 detects that the temperature of the air at the air inlet 131 is less than or equal to the preset value, the heater 20 starts to heat the air entering from the air inlet 131, and the second detection component 15 can detect the first pressure value of the smoke at the smoke inlet 121 and the second pressure value of the smoke at the smoke outlet 122. When the difference between the first pressure value and the second pressure value is greater than the preset pressure difference, the working power of the heater 20 increases to improve the heating effect on the air, until the temperature detected by the third detection component 17 is greater than the dew point temperature detected by the first detection component 14 or when the third detection component 17 detects that the temperature of the air at the air inlet 131 is greater than the preset value, the heater 20 stops working to minimize the smoke exhaust temperature and recover the waste heat of the smoke. Among them, the first detection component 14 can be a dew point transmitter. The second detection component 15 can be a pressure sensor. The third detection component 17 is a temperature sensor.

[0059] It is understandable that the various different operating modes of the heater 20 may be on, off, constant power operation, or variable power operation, etc.

[0060] Optionally, the waste heat recovery device 100 also includes a control mechanism 30, which is electrically connected to the air preheater 10 and the air heater 20 respectively to coordinate and control the air preheater 10 and the air heater 20 to cooperate with each other to achieve automated and intelligent management of the waste heat recovery device 100.

[0061] Optionally, the air duct mechanism 13 also includes a connecting branch 133, which is used to connect the air inlet 131 and the air outlet 132 to transmit the hot air discharged from the air outlet 132 to the air inlet 131. When the heater 20 operates at maximum power and still cannot make the temperature of the air entering the air inlet 131 reach a preset condition, the heated air of the air outlet 132 is transmitted to the air inlet 131 through the connecting branch 133 to increase the temperature of the air entering the air inlet 131.

[0062] Optionally, the air duct mechanism 13 further includes a valve 134, which is disposed on the connecting branch 133 and is used to control the opening and closing of the connecting branch 133 and the size of the passage. The valve 134 may be a bypass valve or a solenoid valve, etc. The valve 134 is communicatively connected with the control mechanism 30 to realize automatic control of the opening and closing of the valve 134 and the size of the passage of the valve 134 through the control mechanism 30.

[0063] Optionally, the smoke duct includes a fourth detection member 16, which is disposed at the smoke outlet 122 and configured to detect the temperature of the smoke at the smoke outlet 122, and is used to monitor the temperature of the smoke at the smoke outlet 122 in real time. The fourth detection member 16 may be a temperature sensor.

[0064] Optionally, the air duct mechanism 13 further includes a third detection member 17, which is disposed at the air inlet 131 and is configured to detect the temperature of the air introduced through the air inlet 131. The control mechanism 30 enables the air heater 20 to switch to different working states according to the temperature of the air introduced through the air duct mechanism 13 detected by the third detection member 17. The third detection member 17 may be a temperature sensor.

[0065] Combination Figure 1-Figure 4 The structure of the heater 20 is described as follows. Figure 1-Figure 4 As shown, the heater 20 includes a driving mechanism 22 and a heating mechanism 23. The heating mechanism 23 is arranged at the output end of the driving mechanism 22. The driving mechanism 22 can drive the heating mechanism 23 to rotate so that the heating mechanism 23 is switched between an on state and a off state.

[0066] Optionally, the heater 20 includes an outer shell 21, a heating mechanism 23 is disposed inside the outer shell 21 and is rotatably connected to the outer shell 21, the number of the heating mechanisms 23 is at least two, and at least two heating mechanisms 23 are arranged at intervals along the length direction of the inner shell 231 to adapt to different sizes of air duct mechanisms 13 and improve the heating effect on the air.

[0067] Specifically, the driving mechanism 22 includes a first driving member 221 and a transmission member 222, wherein the transmission member 222 is arranged at the output end of the first driving member 221, and the heating mechanism 23 is connected to the transmission member 222, and the first driving member 221 drives the transmission member 222 to move, thereby driving the heating mechanism 23 to rotate. Among them, the transmission member 222 can be a worm gear structure, and the first driving member 221 drives the turbine to rotate, thereby driving the worm to move, and a plurality of racks are arranged on the worm, and each heating mechanism 23 is provided with a gear, and the gear is meshed with the corresponding rack, thereby driving at least two heating mechanisms 23 to rotate simultaneously. Among them, the first driving member 221 can be a motor. In other embodiments, each heating mechanism 23 is provided with a corresponding rotation drive structure, and the rotation drive structure drives the corresponding heating mechanism 23 to rotate.

[0068] Furthermore, the heater 20 also includes a manual start-stop component 27, on which a gear is provided. The gear on the manual start-stop component 27 is meshed with the rack on the worm gear. Rotating the manual start-stop component 27 drives the worm gear to move, thereby driving at least two heating mechanisms 23 to rotate simultaneously.

[0069] Specifically, the heating mechanism 23 includes an inner shell 231, a water collecting tank 232 and at least two tube bundles 233. The inner shell 231 is rotatably connected to the outer shell 21. The water collecting tank 232 is arranged on the inner shell 231. The tube bundle 233 is connected to the water collecting tank 232 and the water collecting tank 232 is arranged at both ends along the axial direction. At least two tube bundles 233 are arranged at intervals along the length direction of the water collecting tank 232. A heat source is arranged in at least one water collecting tank 232. The heat source can be moved into at least two tube bundles 233 to increase the contact area with the air, thereby improving the heating effect on the air. The heat source can be hot water or high-temperature steam.

[0070] Furthermore, the air heater 20 further includes a second driving member 24, which is used to drive the heat source to move from one water collecting tank 232 to another water collecting tank 232 via the tube bundle 233, so as to achieve continuous heating of the air. The second driving member 24 may be a variable frequency pump, which can drive the heat source to enter one of the water collecting tanks 232 via the heat source inlet 25, and the heat source enters another water collecting tank 232 after completing heat exchange with the hot air via at least two tube bundles 233, and finally is discharged via the water outlet 26.

[0071] The variable frequency pump can operate at a specific power and can also operate at a variable power, so that the heater 20 has a fixed power operation mode and a variable power operation mode. The control mechanism 30 can control the opening, closing, specific power operation or variable power operation of the variable frequency pump according to the data detected by the first detection member 14, the second detection member 15, the third detection member 17 and the fourth detection member 16. It should be noted that the control mechanism 30 is a prior art, and the present embodiment can use any control mechanism 30 that can achieve the above functions.

[0072] Optionally, the heating mechanism 23 also includes two pipe assemblies 234, which are connected to corresponding water collecting tanks 232. After the heat source enters the heat source inlet 25, it enters the water collecting tank 232 connected to the pipe assembly 234 through one of the pipe assemblies 234, and then enters the other water collecting tank 232 after passing through the tube bundle 233 and is connected to the water outlet through the pipe assembly 234 connected to the water collecting tank 232.

[0073] Specifically, the pipe assembly 234 includes a support pipe 2341 and a hose 2342. The support pipe 2341 is connected to the water collecting tank 232 and is rotatably connected to the outer shell 21. The hose 2342 is arranged in the support pipe 2341 and connected to the water collecting tank 232. The support pipe 2341 has a protective effect on the hose 2342 to prevent the hose 2342 from twisting when the heating mechanism 23 rotates and affecting the delivery of the heat source.

[0074] Optionally, the heating mechanism 23 further includes a support member 235, which is disposed on the inner shell 231, and at least two tube bundles 233 are respectively penetrated through the support member 235, and the support member 235 is provided to support the tube bundle 233 to prevent the tube bundle 233 from being deformed during use. Specifically, the support member 235 is a plate-like structure, and at least two through holes are opened on the support member 235 of the plate-like structure, and the tube bundle 233 can pass through the corresponding through holes and be supported on the support member 235.

[0075] like Figure 3 As shown, when the temperature of the air inlet 131 detected by the third detection member 17 is greater than the preset value, the air preheater 10 has no condensation corrosion phenomenon, and the heater 20 does not need to work at this time. The first driving member 221 drives the heating mechanism 23 to rotate parallel to the air flow direction to reduce wind resistance. Figure 4 As shown, when the temperature detected by the third detection member 17 is less than or equal to the dew point temperature detected by the first detection member 14 or when the third detection member 17 detects that the temperature of the air at the air inlet 131 is less than or equal to the preset value, the first driving member 221 drives the heating mechanism 23 to rotate to a direction perpendicular to the air flow, and the second driving member 24 drives the heat source to pass through the heat source inlet 25, one of the hoses 2342, one of the water collecting tanks 232, the tube bundle 233, another water collecting tank 232, and another hose 2342 in sequence and then be discharged from the water outlet 26 to complete the heating of the air.

[0076] For ease of understanding, combined Figure 1-Figure 4 The working process of the waste heat recovery device 100 is described as follows:

[0077] 1) When the temperature of the air inlet 131 detected by the third detection member 17 is greater than a preset value, the heater 20 does not need to work;

[0078] 2) When the temperature detected by the third detection member 17 is less than or equal to the dew point temperature detected by the first detection member 14 or when the temperature of the air at the air inlet 131 detected by the third detection member 17 is less than or equal to a preset value, the first driving member 221 drives the heating mechanism 23 to rotate perpendicular to the air flow direction, and the second driving member 24 drives the heat source to enter the heating mechanism 23, thereby heating the air entering through the air inlet 131;

[0079] 3) When the difference between the first pressure value and the second pressure value detected by the second detection member 15 is greater than the preset pressure difference, the control mechanism 30 controls the working power of the second driving member 24 to increase, automatically adjusts the supply amount of the heat source entering the heating mechanism 23, and further controls the temperature of the air entering the air inlet 131;

[0080] 4) When the power of the second driving member 24 increases to the maximum and the difference between the first pressure value and the second pressure value is still greater than the preset pressure difference, the valve 134 is opened, and the heated air passes through the air outlet 132 and the connecting branch 133, enters from the air inlet 131, and then cooperates with the heater 20 to heat the air. The control mechanism 30 controls the opening and opening and closing of the valve 134 according to the size of the pressure difference, and controls the working mode of the heater 20 at the same time, until the temperature detected by the third detection member 17 is greater than the temperature detected by the first detection member 14, and the heater 20 stops working.

[0081] This embodiment also provides a control method for a waste heat recovery device, which is implemented using the waste heat recovery device 100 described above, and includes the following steps:

[0082] When determining whether the temperature of the air in the air inlet 131 detected by the third detection element 17 is greater than a preset value;

[0083] If yes, the heater 20 does not need to work;

[0084] If not, when the temperature detected by the third detection element 17 is less than or equal to the dew point temperature detected by the first detection element 14 or when the temperature detected by the third detection element 17 at the air inlet 131 is less than or equal to a preset value, the heater 20 starts to work and heats the air.

[0085] Through the above method, condensation caused by too low flue gas temperature can be avoided, the problems of condensation corrosion and ash accumulation and blockage of the air preheater 10 caused by changes in coal type and ambient wind temperature can be solved, and the working efficiency of the air waste heat device and the stable operation of the system can be ensured.

[0086] After the air heater 20 starts to work and heats the air, the following steps are also included:

[0087] Determine whether the difference between the first pressure value and the second pressure value detected by the second detection element 15 is greater than a preset pressure difference;

[0088] If not, the heater 20 operates at a specific power;

[0089] If so, the control mechanism 30 controls the working power of the second driving member 24 to increase, and automatically adjusts the supply amount of the heat source entering the heating mechanism 23 .

[0090] Through the above steps, the working efficiency of the heater 20 is improved, the time for the heater 20 to heat the air is shortened, and the production efficiency is improved.

[0091] After the control mechanism 30 controls the working power of the second driving member 24 to increase and automatically adjusts the supply amount of the heat source entering the heating mechanism 23, the following steps are also included:

[0092] Determine whether the difference between the first pressure value and the second pressure value detected by the second detection element 15 is greater than a preset pressure difference;

[0093] If not, the control mechanism 30 controls the working power of the second driving member 24 to decrease, and automatically adjusts the supply amount of the heat source entering the heating mechanism 23;

[0094] If so, the control mechanism 30 controls the valve 134 to open, and the heated air passes through the air outlet 132 and the connecting branch 133 and enters the heater 20 through the air inlet 131 .

[0095] Through the above steps, when the heater 20 reaches the maximum load, the heating effect on the air can still be guaranteed.

[0096] Note that in the description of this specification, the description with reference to the terms "some embodiments", "other embodiments", etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner.

[0097] The above are only preferred embodiments of the present invention and the technical principles used. Those skilled in the art will understand that the present invention is not limited to the specific embodiments described herein, and that various obvious changes, readjustments and substitutions can be made by those skilled in the art without departing from the scope of protection of the present invention. Therefore, although the present invention has been described in more detail through the above embodiments, the present invention is not limited to the above embodiments, and may include more other equivalent embodiments without departing from the concept of the present invention, and the scope of the present invention is determined by the scope of the appended claims.

Claims

1. Waste heat recovery device, characterized in that: include: An air preheater (10) comprises a flue gas duct mechanism (12), an air duct mechanism (13), a first detection element (14), a second detection element (15) and a third detection element (17); the flue gas duct mechanism (12) has a flue gas inlet (121) and a flue gas outlet (122); the first detection element (14) is configured to detect the dew point temperature of the flue gas at the flue gas inlet (121); the second detection element (15) is capable of detecting a first pressure value of the flue gas at the flue gas inlet (121) and a second pressure value of the flue gas at the flue gas outlet (122); and the third detection element (17) is configured to detect the temperature of air passing into the air duct mechanism (13); A heater (20), wherein the heater (20) is configured to heat the air passing through the air duct mechanism (13), and the heater (20) is preset with a plurality of different working modes. The heater (20) is communicatively connected with the first detection member (14), the second detection member (15), and the third detection member (17), and can select different working modes to heat the air passing through the air duct mechanism (13).

2. The waste heat recovery device according to claim 1, characterized in that: The air duct mechanism (13) comprises: A connecting branch (133), wherein the air duct mechanism (13) has an air inlet (131) and an air outlet (132), and the connecting branch (133) is used to connect the air inlet (131) and the air outlet (132) so as to transmit the hot air discharged from the air outlet (132) to the air inlet (131).

3. The waste heat recovery device according to claim 2, characterized in that: The air duct mechanism (13) further comprises: A valve (134) is arranged on the connecting branch (133).

4. The waste heat recovery device according to claim 1, characterized in that: The air duct mechanism (13) further comprises: The fourth detection element (16) is configured to detect the temperature of the smoke at the smoke outlet (122).

5. The waste heat recovery device according to any one of claims 1 to 4, characterized in that: The waste heat recovery device further comprises a control mechanism (30), wherein the control mechanism (30) is electrically connected to the air preheater (10) and the air heater (20) respectively.

6. The waste heat recovery device according to any one of claims 1 to 4, characterized in that: The air heater (20) comprises: A driving mechanism (22); The heating mechanism (23) is arranged at the output end of the driving mechanism (22), and the driving mechanism (22) can drive the heating mechanism (23) to rotate so that the heating mechanism (23) is switched between an on state and a off state.

7. The waste heat recovery device according to claim 6, characterized in that: The air heater (20) further comprises a second driving member (24), and the heating mechanism (23) comprises: Inner housing (231); A water collecting tank (232) is arranged on the inner shell (231); At least two tube bundles (233), the water collecting tanks (232) are provided at both ends of the tube bundle (233) along the axial direction, at least two of the tube bundles (233) are arranged at intervals along the length direction of the water collecting tank (232), and the second driving member (24) is used to drive the heat source to move from one of the water collecting tanks (232) to another of the water collecting tanks (232) via the tube bundle (233).

8. A control method for a waste heat recovery device, characterized in that: The method is completed by using the waste heat recovery device according to any one of claims 1 to 7, comprising the following steps: When determining whether the temperature of the air at the air inlet (131) detected by the third detection element (17) is greater than a preset value; If yes, the heater (20) does not need to work; If not, when the temperature detected by the third detection element (17) is less than or equal to the dew point temperature detected by the first detection element (14) or when the third detection element (17) detects that the temperature at the air inlet (131) is less than or equal to a preset value, the heater (20) starts to operate and heats the air.

9. The control method of the waste heat recovery device according to claim 8, characterized in that: After the air heater (20) starts to work and heats the air, the following steps are also included: Determining whether the difference between the first pressure value and the second pressure value detected by the second detection element (15) is greater than a preset pressure difference; If not, the control mechanism (30) controls the working power of the second driving member (24) to decrease, and automatically adjusts the supply amount of the heat source entering the heating mechanism (23); If so, the control mechanism (30) controls the valve (134) to open, and the heated air passes through the air outlet (132) and the connecting branch (133), and enters the heater (20) from the air inlet (131).

10. A boiler, characterized in that It comprises a waste heat recovery device as described in any one of claims 1 to 7.

Images