Waste heat recovery system and control method

Abstract

The invention relates to a waste heat recovery system. A waste heat recovery system includes: a first exhaust line communicating to an air outlet of a first heat treatment device and an external space; comprising a first air return pipeline of air return equipment and a first air inlet communicated with the first exhaust pipeline and the first heat treatment device; comprising a first control valve, and is communicated to an air outlet of the second heat treatment device and the external space; comprising a second control valve and is communicated to the second exhaust pipeline and a second air inlet of the first heat treatment device; and the temperature of the first path of return air transmitted through the first return air pipeline is lower than that of the second path of return air transmitted through the second return air pipeline. According to the waste heat recovery system, high-temperature return air of one heat treatment device can be guided into the other heat treatment device, so that efficient gas recycling is achieved, and energy consumption can be reduced.

Description

Technical Field

[0001] The present disclosure relates to a thermal energy device, and more particularly, to a waste heat recovery system, a waste heat recovery control method, a computing device, a production processing system, a computer-readable storage medium, and a computer program product. Background Art

[0002] In applications such as industrial production, materials are usually processed by multiple heat treatment devices in a heat treatment system, and the tail gas generated after the heat treatment device is processed will contain waste heat. In the prior art, the waste heat is usually simply recycled. For example, the waste heat air of a single heat treatment device is introduced into the heat treatment device as return air, while the tail gas of other heat treatment devices still contains a large amount of waste heat (for example, high-temperature tail gas), but is directly discharged to the external environment (such as the atmosphere), which makes the waste heat in the system not fully recycled, resulting in waste of resources and low waste heat recovery rate.

[0003] For example, the production line may include a hot blast furnace for generating hot blast and an expansion furnace for calcining perlite. The tail gas from calcining perlite still contains a large amount of waste heat. In the existing production line, the tail gas is directly discharged into the atmosphere, and the heat contained in it cannot be directly utilized. Summary of the invention

[0004] The present disclosure at least partially solves the problems in the prior art by introducing the relatively high temperature tail gas of a heat treatment device into another heat treatment device.

[0005] A first aspect of the present disclosure provides a waste heat recovery system, comprising: a first exhaust duct connected to an air outlet of a first heat treatment device and an external space, the first exhaust duct comprising a first exhaust device; a first return air duct connected to the first exhaust duct and a first air inlet among multiple air inlets of the first heat treatment device, the first return air duct comprising a return air device; a second exhaust duct connected to an air outlet of a second heat treatment device and an external space, the second exhaust duct comprising a first control valve and a second exhaust device; a second return air duct connected to the second exhaust duct and a second air inlet among multiple air inlets of the first heat treatment device, the second return air duct comprising a second control valve, and the first control valve is arranged between the second return air duct and the external space; wherein the temperature of the first return air transmitted through the first return air duct is lower than the temperature of the second return air transmitted through the second return air duct.

[0006] The second aspect of the present disclosure provides a waste heat recovery control method, which is applicable to the waste heat recovery system according to the first aspect above, and the method includes: adjusting the pressure in the first heat treatment device and the pressure upstream of the second control valve in the second return air duct by controlling the return air equipment, the first control valve and the second control valve.

[0007] A third aspect of the present disclosure provides a computing device, comprising: at least one processor; and a memory for storing computer executable instructions, which, when executed, enable the at least one processor to execute the waste heat recovery control method according to the second aspect.

[0008] A fourth aspect of the present disclosure provides a production processing system, comprising the waste heat recovery system according to the first aspect or the computing device according to the third aspect.

[0009] A fifth aspect of the present disclosure provides a computer-readable storage medium having computer-executable instructions stored thereon, wherein the computer-executable instructions are used to execute the waste heat recovery control method according to the second aspect described above.

[0010] A sixth aspect of the present disclosure provides a computer program product, comprising computer executable instructions, which, when executed, enable at least one processor to perform the waste heat recovery control method according to the second aspect.

[0011] The technical effect of the present disclosure is that the higher temperature exhaust gas from one heat treatment device can be introduced as return air into another heat treatment device, thereby reducing the use of colder temperature exhaust gas as return air, so as to achieve efficient gas circulation, thereby fully recovering and utilizing waste heat, improving the waste heat recovery rate, and saving energy at the same time. By automatically controlling the introduction of return air, it is ensured that waste heat recovery does not affect the normal operation of the two heat treatment devices. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] The features, advantages and other aspects of the embodiments of the present disclosure will become more apparent with reference to the following detailed description in conjunction with the accompanying drawings, in which several embodiments of the present disclosure are shown in an exemplary and non-limiting manner. In the accompanying drawings:

[0013] Figure 1 An existing waste heat recovery system for a heat treatment device is shown;

[0014] Figure 2 A first exemplary waste heat recovery system for multiple heat treatment devices according to an embodiment of the present disclosure is shown;

[0015] Figure 3A second exemplary waste heat recovery system for multiple heat treatment devices according to an embodiment of the present disclosure is shown;

[0016] Figure 4 A third exemplary waste heat recovery system for a plurality of heat treatment devices according to an embodiment of the present disclosure is shown;

[0017] Figure 5 An exemplary waste heat recovery control method according to an embodiment of the present disclosure is shown;

[0018] Figure 6 A state transition diagram of an exemplary waste heat recovery process according to an embodiment of the present disclosure is shown;

[0019] Figure 7 A waste heat recovery control method in a startup state according to an embodiment of the present disclosure is shown;

[0020] Figure 8 A waste heat recovery control method in a waste heat stable state according to an embodiment of the present disclosure is shown;

[0021] Fig. 9 A waste heat recovery control method in a shutdown state according to an embodiment of the present disclosure is shown;

[0022] Fig.10 An exemplary waste heat recovery control method according to an embodiment of the present disclosure is shown;

[0023] Fig.11 An exemplary closed-loop control process according to an embodiment of the present disclosure is shown;

[0024] Fig.12 A block diagram of an exemplary computing device according to an embodiment of the present disclosure is shown.

[0025] refer to Figure 1, shows an existing waste heat recovery system 100 for a heat treatment device 101. The system 100 can be, for example, a waste heat recovery system for a heat treatment device 101 such as a hot blast furnace. The system 100 includes a first exhaust air duct 106, a first return air duct 107, and a plurality of fresh air ducts 108 and 109 (the number shown is 2, which is only for illustration and not for limitation, and the number can be 1 or more than 2). The heat treatment device 101 can be used to generate hot air to provide heat for the heat treatment material. The first exhaust duct 106 is connected to the air outlet 1012 of the heat treatment device 101 and the external space 105 (for example, the atmospheric environment), and the first exhaust duct 106 includes a first exhaust device 102, an air inlet 1021 of the first exhaust device 102 is connected to the air outlet 1012 of the heat treatment device 101 to discharge the hot air (also called tail gas or flue gas, etc.) after the heat treatment, and the air outlet 1022 of the first exhaust device 102 is connected to the external space 105. The first return air duct 107 is connected to the first exhaust duct 106 and the first air inlet 1011a of the heat treatment device 101 to obtain at least a part of the discharged hot air from the first exhaust duct 106, and then used to maintain or control the pressure in the heat treatment device 101 (such as the space in the furnace of the hot blast furnace). The first return air duct 107 includes a return air device 103, an air inlet 1031 of the return air device 103 is connected to the air outlet 1022 of the first exhaust air device 102, and the air outlet 1032 of the return air device 103 is connected to the first air inlet 1011a of the heat treatment device 101. The fresh air ducts 108 and 109 are connected between the external cooling air source 110 and the second air inlets 1011b and 1011c of the heat treatment device 101 to cool one or more parts of the heat treatment device 101, such as the furnace head 1013, the furnace wall (not shown) or other parts. The cold air inlet of the heat treatment device 101 can be set close to the part that needs to be cooled, for example, the air inlet 1011c is close to the furnace head 1013, and the air inlet 1011b is close to the furnace wall. The fresh air ducts 108 and 109 may include a fresh air device 104 (one is shown in the figure for illustration only and not limitation. Each fresh air duct may also include a separate fresh air device, or multiple fresh air ducts may share a fresh air device). The air inlet 1041 of the fresh air device 104 is connected to the external cooling air source 110, and the air outlet 1042 of the fresh air device 104 is connected to the second air inlet 1011b, 1011c of the heat treatment device 101. Each of the first exhaust device 102, the return air device 103, and the fresh air device 104 may include a fan, and the air volume of the fan is controllable. In addition, the hot air furnace can also supplement the air in the furnace by various methods, such as combustion-supporting air, waste heat, or an external air source, as is well known in the art. As previously mentioned, in Figure 1In the system 100, only the waste heat air of the heat treatment device 101 itself is introduced into the heat treatment device 101 as return air, without considering the use of waste heat from other heat treatment devices (for example, exhaust gas or flue gas with higher temperature), which makes the waste heat in the system not fully recovered and utilized.

[0026] refer to Figure 2 , shows a first exemplary waste heat recovery system 200A applied to multiple heat treatment devices according to an embodiment of the present disclosure. The system 200A can be used for a first heat treatment device 201 and a second heat treatment device 212, and the temperature of the tail gas discharged by the second heat treatment device 212 (e.g., 130°) is higher than the temperature of the tail gas discharged by the first heat treatment device 201 (e.g., 80°). For example, the first heat treatment device 201 can be a hot blast furnace for drying materials such as desulfurized gypsum, and the pressure in the device 201 is the furnace pressure of the hot blast furnace. For example, the second heat treatment device 212 can be a calcining device for calcining materials, and the second heat treatment device 212 is located downstream of the production line relative to the first heat treatment device 201. For example, the second heat treatment device 212 can be an expansion furnace for calcining materials such as perlite to generate expanded perlite, and the pressure in the device 212 is the furnace pressure of the expansion furnace. System 200A includes a first heat treatment device 201, a first exhaust air duct 206, a first return air duct 207, and a plurality of fresh air ducts 208, 209 (the number shown is 2, which is for illustration only and not limitation, and the number can be 1 or more than 2). The first return air duct 207 may include a first exhaust air device 202. The first return air duct 207 may include a return air device 203. The fresh air ducts 208, 209 may include a fresh air device 204. The first heat treatment device 201, the first exhaust air duct 206, the first return air duct 207, and a plurality of fresh air ducts 208, 209, and the devices 202, 203, 204 in these ducts are similar to those described above. Figure 1 The described first heat treatment device 101, the first exhaust air duct 106, the first return air duct 107, and the multiple fresh air ducts 108, 109, and the equipment 102, 103, 104 in these ducts (similar figure marks change from "1xx" plus 100 to "2xx" or from "1xxx" plus 1000 to "2xxx") are not described in detail.

[0027] Different from Figure 1 , Figure 2The first heat treatment device 201 also includes a third air inlet 2011d, which can be connected to the air outlet 2131 of the second heat treatment device 212 to obtain at least a portion of the higher temperature exhaust gas from the second heat treatment device 212. Specifically, the system 200A also includes a second exhaust duct 215, which is connected to the air outlet 2111 of the second heat treatment device 101 and the external space 216 (e.g., the atmospheric environment). The second exhaust duct 215 includes a second exhaust device 213 and a first control valve 214, the air inlet 2131 of the second exhaust device 213 is connected to the air outlet 2111 of the second heat treatment device 212 to discharge the hot air (also called exhaust gas or flue gas) after heat treatment, and the air outlet 2132 of the second exhaust device 213 is connected to the inlet 2141 of the first control valve 214, and the outlet 2142 of the first control valve 214 is connected to the external space 216. The system 200 further includes a second air return line 218, which is connected to the second air exhaust line 215 and the third air inlet 2011d of the first heat treatment device 201. The second air return line 218 includes a second control valve 217, an inlet 2171 of the second control valve 217 is connected to the second air exhaust line 215, and an outlet of the second control valve 217 is connected to the third air inlet 2011d. Figure 2 As shown, the first control valve 214 is disposed between the second return air duct 218 and the external space 216, that is, the inlet 2171 of the second control valve 217 is connected between the first control valve 214 and the second exhaust device 213. Similarly, the second exhaust device 213 may include a fan, and the air volume of the fan is controllable.

[0028] like Figure 2As shown, the first return air duct 207 in the system 200 transmits at least a portion of the hot air discharged from the first heat treatment device 201 as the first return air to the first heat treatment device 201 (for example, the furnace of the hot blast furnace), and transmits at least a portion of the hot air discharged from the second heat treatment device 212 (such as) as the second return air to the first heat treatment device 201. This waste heat recovery may affect the pressure change in the first and second heat treatment devices at the same time. In order to prevent the operation of the waste heat recovery system from affecting the normal operation of the first and second heat treatment devices, it is necessary to control the pressure stability in the two heat treatment devices to avoid unstable operation of the heat treatment devices due to the pressure fluctuations in the heat treatment devices. For example, the first and second return air are used to maintain or control the pressure in the heat treatment device 201. For example, the pressure stability in the second heat treatment device can be determined by determining whether the pressure at the upstream of the second control valve 217 in the second return air duct 218 (such as the valve inlet 2171) is within the allowable range. For example, the pressure at the upstream of the second control valve 217 is adjusted so as to introduce the tail gas from the second exhaust pipe 215 into the first heat treatment device 201. For example, when the pressure at the upstream of the second control valve 217 is inappropriate, the tail gas may not be introduced from the second exhaust pipe 215 or only a small amount of tail gas may be introduced into the first heat treatment device 201, for example, due to the chimney effect of the second exhaust pipe 215, which also affects the pressure stability in the second heat treatment device 212.

[0029] For example, the system 200 may further include a control device 221, which is operatively coupled to the return air device 203, the first control valve 214, and the second control valve 217 (as indicated by the dotted line) to adjust the pressure in the first heat treatment device 201 and the pressure upstream of the second control valve 217 in the second return air duct 218. For example, a pressure detection unit 219 (for example, a pressure sensor is disposed in the first heat treatment device 201) may be provided to detect the pressure in the first heat treatment device 201, and the control device 221 may obtain the detected pressure in the first heat treatment device 201 from the pressure detection unit 219. For example, a pressure detection unit 220 (for example, a pressure sensor is disposed in the second duct 218 upstream of the second control valve 217) may be provided to detect the pressure upstream of the second control valve 217, and the control device 221 may obtain the detected pressure upstream of the second control valve 217 from the pressure detection unit 220.

[0030] The control device 221 can be implemented by one or more processing elements, such as a logic gate array, a controller and an arithmetic logic unit, a digital signal processor, a microcomputer, a programmable logic controller (PLC), a field programmable gate array (FPGA), a programmable logic array, a microprocessor, or any other device or device combination known in the art. For example, the control device 221 can be communicatively coupled to a controller associated with the return air device 203 (such as a fan controller), a controller associated with the first control valve 214 (such as a valve controller, a valve positioner, a valve actuator (e.g., a pneumatic or electric actuator), etc.), and a controller associated with the second control valve 217 (such as a valve controller, a valve positioner, a valve actuator (e.g., a pneumatic or electric actuator), etc.). The control device 221 can adjust the corresponding changes of the return air device 203, the first control valve 214, and the second control valve 217, such as the return air volume, valve opening, etc., by sending driving instructions, commands or signals to the controllers associated with the return air device 203, the first control valve 214, and the second control valve 217, so as to use as much higher temperature exhaust gas from the second heat treatment device 212 as possible as return air to be introduced into the first heat treatment device 201.

[0031] refer to Figure 3 , shows a second exemplary waste heat recovery system 200B for multiple heat treatment devices according to an embodiment of the present disclosure. Figure 3 The system 200B is similar to Figure 2 In the system 200A, in addition to the first return air duct 217 being connected to the fresh air ducts 208 and 209 through the guide mechanism 211, at least a portion of the return air delivered via the first return air duct 217 can be delivered to the second air inlets 2011b and 2011c of the first heat treatment device 201 via the fresh air ducts 208 and 209 to cool one or more parts of the first heat treatment device 201, such as the furnace head 2013, the furnace wall (not shown) or other parts. The cooling air from the external cooling air source 210 can also be delivered to the second air inlets 2011b and 2011c via the fresh air ducts 208 and 209 to cool the one or more parts.

[0032] refer to Figure 4 , shows a third exemplary waste heat recovery system 200C for multiple heat treatment devices according to an embodiment of the present disclosure. Figure 4 The system 200C is similar to Figure 2 System 200A and Figure 3 In the system 200B, in addition to the first return air duct 217 being connected to the fresh air ducts 208 and 209 through the guide mechanism 211, the fresh air device 204 and the external cooling air source 210 are eliminated, so that only at least a part of the return air is required to cool one or more parts of the first heat treatment device 201.

[0033] and Figure 1 Compared with the waste heat recovery system 100, Figure 2-Figure 4 The waste heat recovery system 200A-200C introduces the higher temperature tail gas from one heat treatment device as return air into another heat treatment device, thereby reducing the use of the lower temperature tail gas as return air, so as to achieve efficient gas circulation, thereby fully recovering and utilizing the waste heat, improving the waste heat recovery rate, and saving energy. In addition, the waste heat recovery system 200A-200B can also automatically control the introduction of return air to ensure that the waste heat recovery does not affect the normal operation of the two heat treatment devices.

[0034] also, Figure 3 and Figure 4 The waste heat recovery systems 200B and 200C introduce the return air with higher temperature into the fresh air duct to cool the parts of the heat treatment device, which can eliminate the need for external cooling air and achieve more efficient recycling of waste gas to reduce exhaust emissions, which is beneficial to environmental protection, reduces air pollution, and at the same time can reduce heat energy loss and save energy consumption.

[0035] For example, the energy savings can be calculated as follows:

[0036] Q=c·ρ·v·Δt

[0037] Where Q is the heating volume v cubic meters (m 3 ) of air, the specific heat of air c = 1.01 kj / kg℃, the air density ρ = 1.205 kg / m 3 , Δt is the temperature rise. The air volume v per unit time can be calculated as the air volume (m 3 / h) multiplied by unit time.

[0038] For example, when a higher temperature return air (e.g., 130°C) is used to replace a lower temperature return air (e.g., 80°C), Δt is 50°C. When the air volume reaches several thousand m 3 / h, it can save several hundred kw of heat. For example, if 200 kw of heat is saved, the natural gas consumption saved per hour is about 20 cubic meters (m 3 ), or converted into 200 kWh of electricity saved per hour, which can significantly save energy consumption (for example, the use of various energy sources, such as gas, oil, biomass fuel or electricity).

[0039] For example, when the cooling air (e.g., room temperature 25°C) is replaced by the return air with a higher temperature (e.g., 80°C), Δt is 55°C. When the air volume reaches several thousand m 3 / h, it can save several hundred kw of heat. For example, if 200 kw of heat is saved, the natural gas consumption saved per hour is about 20 cubic meters (m 3 ), or converted into 200 kWh of electricity saved per hour, which can significantly save energy consumption (for example, the use of various energy sources, such as gas, oil, biomass fuel or electricity).

[0040] For example, the heat treatment device (such as a hot blast furnace) may include a heat treatment device that burns coal, gas, oil, burns biomass, or is electrically heated, thereby saving corresponding energy consumption.

[0041] Figure 5 An exemplary waste heat recovery control method 300 according to an embodiment of the present disclosure is shown. The method 300 may be applicable to Figure 2-Figure 4 The waste heat recovery system 200A-200C can be Figure 2-Figure 4 The control device 221 or Fig.11 The method 300 includes steps 310 and 320.

[0042] In step 310, an instruction on starting or stopping waste heat recovery is obtained. For example, a user input on starting or stopping waste heat recovery can be received via a user interface, and the control device 221 can start or stop waste heat recovery in response to receiving the user input. For example, when a fault indication is received about at least one of the first heat treatment device and the second heat treatment device, waste heat recovery can be stopped. Alternatively, an instruction on starting or stopping waste heat recovery can be obtained via other means, which is not limited herein.

[0043] In step 320 , the pressure in the first heat treatment device 201 and the pressure upstream of the second control valve 217 in the second return air line 218 are adjusted by controlling the return air device 203 , the first control valve 214 and the second control valve 217 .

[0044] according to Figure 5 The method 300 can automatically control the introduction of return air to ensure that the waste heat recovery does not affect the normal operation of the two heat treatment devices.

[0045] In some examples, step 320 may include: the control device performs closed-loop control on the pressure in the first heat treatment device 201 by controlling at least one of the return air device 203 and the second control valve 217, so that the pressure in the first heat treatment device 201 is maintained in a first stable range, and performs closed-loop control on the pressure in the second return air duct 218 by controlling the first control valve 214, so that the pressure in the second return air duct 218 is maintained in a second stable range.

[0046] For example, the first stable range P1_lower ~P 1_upper The second stable range P is a negative pressure value relative to the external air pressure P0 (for example, standard atmospheric pressure) to prevent heat leakage. 2_lower ~P 2_upper The pressure value is positive relative to the external air pressure P0 (for example, standard atmospheric pressure) to ensure the pressure stability in the second heat treatment device 212 and to prevent the chimney effect of the second exhaust duct 215 from causing the inability to introduce exhaust gas or only a small amount of exhaust gas to be introduced into the first heat treatment device 201 from the second exhaust duct 215.

[0047] In some examples, step 320 may include: the control device controls the return air device 203, the first control valve 214 and the second control valve 217 in multiple states of waste heat recovery to adjust the pressure in the first heat treatment device 201 and the pressure in the second return air duct 218.

[0048] refer to Figure 6 , an exemplary state transition diagram 400 of an exemplary waste heat recovery process according to an embodiment of the present disclosure is shown. The state transition diagram 400 includes three states: a startup state 410, a waste heat stable state 420, and a shutdown state 430.

[0049] For example, when an instruction to start waste heat recovery is obtained, the waste heat recovery process enters the start state 410. In the start state, a corresponding waste heat recovery control method (described below) may be executed. Figure 7 Method 500, Fig.10 Method 800, Fig.11 process 900).

[0050] In the start state 410, 1) when the condition 401 is satisfied (as described below with respect to Figure 7 1) the waste heat recovery process is transferred from the startup state 410 to the waste heat stable state 420, 2) when the condition 403 is met, the waste heat recovery process is transferred from the startup state 410 to the shutdown state 430, otherwise 3) the waste heat recovery process is still in the startup state 410. For example, the condition 403 may be at least one of obtaining a fault indication about at least one of the first heat treatment device and the second heat treatment device, obtaining an indication about stopping waste heat recovery, obtaining other fault indications, etc.

[0051] In the residual heat stable state 420, a corresponding residual heat recovery control method (as described below) may be executed. Figure 8 Method 600, Fig.10 Method 800, Fig.11In the residual heat stable state 420, when the condition 402 is satisfied, the residual heat recovery process may be transferred from the residual heat stable state 420 to the shutdown state 430, otherwise the residual heat recovery process remains in the residual heat stable state 420. For example, the condition 402 may be at least one of obtaining a fault indication about at least one of the first heat treatment device and the second heat treatment device, obtaining an indication about stopping residual heat recovery, obtaining other fault indications, etc.

[0052] In the shutdown state 430, a corresponding waste heat recovery control method (as described below) may be executed. Fig. 9 4. Method 700 of FIG. 4. When condition 404 is met, the waste heat recovery process may be transferred from shutdown state 430 to startup state 410. For example, condition 404 may be that a fault in the waste heat recovery system has been eliminated and an instruction to start waste heat recovery has been obtained.

[0053] refer to Figure 7 , shows an exemplary waste heat recovery control method 500 in the startup state 410 according to an embodiment of the present disclosure. The method 500 may be applicable to Figure 2-Figure 4 The waste heat recovery system 200A-200C can be Figure 2-Figure 4 The control device 221 or Fig.11 The method 500 includes steps 510-560.

[0054] At step 510, the opening of the second control valve 217 is initially set to a first predetermined value (e.g., 10%). For example, the control device 221 may send a drive instruction, command, or signal to a controller associated with the second control valve 217 to initially adjust the opening of the second control valve 217 to a predetermined opening.

[0055] In step 520, the opening of the second control valve 217 is increased, and at this opening, the pressure in the first heat treatment device 201 is closed-loop controlled by controlling the operating parameters (e.g., fan frequency, fan speed, etc.) of the return air device 203. In this step, the second control valve 217 is gradually opened so that the higher temperature tail gas from the second heat treatment device 212 can gradually increase and enter the first heat treatment device 201, and the lower temperature tail gas from the first heat treatment device 201 entering the first heat treatment device 201 is gradually reduced by controlling the operating parameters of the return air device 203 (e.g., reducing the fan frequency, reducing the fan speed, etc.), thereby gradually improving the energy saving.

[0056] At step 530, it is determined whether the operating parameter of the return air device 203 drops to an operating threshold (e.g., minimum fan frequency, minimum fan speed, etc.). If the operating parameter of the return air device 203 does not drop to the operating threshold ("No" branch), the method 500 proceeds to step 540. If the operating parameter of the return air device 203 drops to the operating threshold ("Yes" branch), the method 500 proceeds to step 550.

[0057] At step 540, it is determined whether the opening of the second control valve 217 increases to an opening threshold (e.g., a settable threshold, such as 90% or other value). If the opening of the second control valve 217 does not increase to the opening threshold ("No" branch), the method 500 returns to step 520. If the opening of the second control valve 217 increases to the opening threshold ("Yes" branch), the method 500 proceeds to step 560.

[0058] In step 550 , it is determined that the operation of switching to closed-loop control of the pressure in the first heat treatment device 201 by controlling the operating parameters of the second control valve 217 will be switched.

[0059] In other words, if the operating parameters of the return air device 203 reach the operating threshold, it is necessary to switch from closed-loop control of the pressure in the first heat treatment device 201 by controlling the operating parameters of the return air device 203 to closed-loop control of the pressure in the first heat treatment device 201 by controlling the operating parameters of the second control valve 217. If the operating parameters of the return air device 203 do not reach the operating threshold, the pressure in the first heat treatment device 201 will still be closed-loop controlled by controlling the operating parameters of the return air device 203.

[0060] At step 560 , it is determined that the waste heat recovery is transferred from the startup state to the waste heat steady state.

[0061] according to Figure 7 In method 500, during the startup phase of waste heat recovery, the first return air volume from the first heat treatment device 201 itself is relatively controllable, while the second return air volume from the second heat treatment device 212 is uncertain. By gradually increasing the second return air volume, it is possible to avoid fluctuations in the second return air that affect the pressure stability in the first and second heat treatment devices.

[0062] The method 500 may further include the following steps: the control device 221 acquires the detection pressure in the first heat treatment device 201; and the closed-loop control of the pressure in the first heat treatment device 201 by controlling the return air device 203 may include: based on the current error between the set pressure of the first heat treatment device 201 and the detection pressure, determining the operating parameters for the return air device 203 (for example, changing its operating parameters through the driving parameters of the controller associated with the return air device 203, etc.) to control the air volume of the return air device 203. Through this step, the pressure in the first heat treatment device 201 can be adjusted to ensure the pressure stability in the first heat treatment device 201 during the waste heat recovery process. In other words, in this step, the operating parameters or air volume of the return air device 203 are automatically controlled according to the pressure in the first heat treatment device 201.

[0063] refer to Figure 8 , shows a waste heat recovery control method 600 in a waste heat stable state 420 according to an embodiment of the present disclosure. The method 600 may be applicable to Figure 2-Figure 4 The waste heat recovery system 200A-200C can be Figure 2-Figure 4 The control device 221 or Fig.11 The method 600 includes steps 610-640.

[0064] In step 610, the pressure in the first heat treatment device 201 is closed-loop controlled by controlling the operating parameters of the return air device 203, similar to the above description of method 500. That is, at a given opening of the second control valve 217, the return air device 203 is controlled to adjust the pressure in the first heat treatment device 201.

[0065] In step 620, it is determined whether the change of the pressure in the first heat treatment device 201 relative to the predetermined pressure exceeds the positive limit value. For example, after adjusting the pressure by controlling the return air device 203, when the pressure in the first heat treatment device 201 is greater than the predetermined pressure and exceeds the positive limit value ("Yes" branch), the method 600 goes to step 630, and when the change of the pressure in the first heat treatment device 201 relative to the predetermined pressure does not exceed the positive limit value ("No" branch), the method 600 goes back to step 610.

[0066] In step 630, the pressure in the first heat treatment device 201 is switched to closed-loop control by controlling the second control valve 217. That is, under given operating parameters of the return air device 203, the second control valve 217 is controlled to adjust the pressure in the first heat treatment device 201.

[0067] In step 640, it is determined whether the change of the pressure in the first heat treatment device 201 relative to the predetermined pressure exceeds the negative limit value. For example, after adjusting the pressure by controlling the second control valve 217, when the pressure in the first heat treatment device 201 is less than the predetermined pressure and exceeds the negative limit value ("Yes" branch), the method 600 turns to step 610 (i.e., switching to closed-loop control of the pressure in the first heat treatment device 201 by controlling the operating parameters of the return air device 203), and when the change of the pressure in the first heat treatment device 201 relative to the predetermined pressure does not exceed the negative limit value ("No" branch), the method 600 turns back to step 630.

[0068] according to Figure 8 According to method 600, when the waste heat recovery process is relatively stable, the return air can be controlled to be introduced into the first heat treatment device 201 by selectively switching between controlling the return air device 203 to adjust the pressure and controlling the second control valve 217 to adjust the pressure (i.e., cyclically transferring control authority), thereby relatively stably adjusting the pressure in the first heat treatment device 201.

[0069] The method 600 may further include the following steps: the control device 221 acquires the detection pressure in the first heat treatment device 201; and the closed-loop control of the pressure in the first heat treatment device 201 by controlling the second control valve 217 may include: based on the current error between the set pressure of the first heat treatment device 201 and the detection pressure, determining the operating parameters for the second control valve 217 (for example, the driving parameters for the controller associated with the second control valve 217, etc.) to control the opening of the second control valve 217. Through this step, the pressure in the first heat treatment device 201 can be adjusted to ensure the pressure stability in the first heat treatment device 201 during the waste heat recovery process. In other words, in this step, the opening of the second control valve 217 is automatically controlled according to the pressure in the first heat treatment device 201.

[0070] Method 600 may further include the following steps: when the pressure in the first heat treatment device 201 is closed-loop controlled by controlling the operating parameters of the return air device 203, if the operating parameters of the return air device 203 reach an operating threshold, it is necessary to switch to closed-loop control of the pressure in the first heat treatment device 201 by controlling the operating parameters of the second control valve 217.

[0071] Method 600 may further include the following steps: when the pressure in the first heat treatment device 201 is closed-loop controlled by controlling the operating parameters of the second control valve 217, if the second control valve 217 increases to an opening threshold, it is necessary to switch to closed-loop control of the pressure in the first heat treatment device 201 by controlling the operating parameters of the return air device 203.

[0072] refer to Fig. 9, shows an exemplary waste heat recovery control method 700 in the shutdown state 430 according to an embodiment of the present disclosure. The method 700 may be applicable to Figure 2-Figure 4 The waste heat recovery system 200A-200C can be Figure 2-Figure 4 The control device 221 or Fig.11 The method 700 includes steps 710-720.

[0073] In step 710, the opening of the second control valve 217 is gradually reduced until the second control valve 217 is closed, and at the same time, the pressure in the first heat treatment device 201 is closed-loop controlled by controlling the operating parameters of the return air device 203 at the opening. For example, the closed-loop control of the pressure in the first heat treatment device 201 by controlling the operating parameters of the return air device 203 (for example, fan frequency, fan speed, etc.) may include: based on the current error between the set pressure of the first heat treatment device 201 and the detected pressure, determining the operating parameters for the return air device 203 (for example, changing its operating parameters through the driving parameters of the controller associated with the return air device 203, etc.) to control the air volume of the return air device 203.

[0074] In step 720 , the closed-loop control of the pressure in the second return air line 218 by controlling the first control valve 214 is exited, and the opening degree of the first control valve 217 is opened to a predetermined opening degree (eg, 100%).

[0075] according to Fig. 9 The method 700 can prevent the exhaust gas from the second heat treatment device 212 from being introduced into the first heat treatment device 201, so as to stop the waste heat recovery in time when a fault occurs, avoid the mutual influence between the first heat treatment device 201 and the second heat treatment device 212, and ensure the normal operation of each heat treatment device, such as the normal discharge of exhaust gas.

[0076] The method 700 may further include the following steps: obtaining an instruction on stopping waste heat recovery (similar to the description of step 310 ), and after obtaining the instruction on stopping waste heat recovery, the waste heat recovery enters the shutdown state 430 .

[0077] refer to Fig.10 , shows an exemplary waste heat recovery control method 800 according to an embodiment of the present disclosure. The method 800 may be applicable to Figure 2-Figure 4 The waste heat recovery system 200A-200C, Figure 6 The startup state 410 and the residual heat stable state 420 are executed, and can be performed by Figure 2-Figure 4 The control device 221 or Fig.11 The method 800 includes steps 810-820.

[0078] In step 810 , when the second control valve 217 is opened, the control device 221 obtains the detection pressure at the upstream of the second control valve 217 in the second pipeline 218 .

[0079] In step 820, the pressure in the second return air duct 218 is closed-loop controlled by controlling the first control valve 214, which may include: based on the current error between the set pressure and the detected pressure of the second duct 218, determining the operating parameters for the first control valve 214 (for example, the driving parameters for the controller associated with the first control valve 214, etc.) to control the opening of the first control valve 214.

[0080] according to Fig.10 The method 800 can adjust the pressure in the second return air duct 218 to ensure the pressure stability in the second heat treatment device 212 during the waste heat recovery process, as described above. In other words, the opening of the first control valve 214 is automatically controlled according to the pressure in the second return air duct 218.

[0081] refer to Fig.11 , shows an exemplary closed-loop control process 900 according to an embodiment of the present disclosure. The closed-loop control process 900 may be applicable to Figure 2-Figure 4 The waste heat recovery system 200A-200C, the aforementioned method (for example, Figure 7 Method 500, Figure 8 Method 600, Fig. 9 Method 700, and Fig.10 The closed-loop control in method 800) and can be Figure 2-Figure 4 The control device 221 or Fig.11 The computing device 1000 executes.

[0082] like Fig.11 As shown, the closed-loop control process 900 includes PID control, wherein box 910 represents the set pressure in the first heat treatment device 201 or the set pressure in the second pipeline 218, box 970 represents the detection pressure in the first heat treatment device 201 or the detection pressure in the second pipeline 218, box 920 represents the current error of the set pressure and the detection pressure of the same object, and boxes 930, 940, 950 represent the proportion, integral, and differential values ​​of the current error, which are linearly combined via corresponding coefficients Kp, Ki, and Kd to generate drive parameters or signals 960 to drive and change the characteristics of the corresponding controlled object (for example, the operating parameters of the return air device 203, the opening of the first control valve 214, and the opening of the second control valve 217). For example, the above coefficients Kp, Ki, and Kd may not be 0, or at least one may be 0 to realize a special case of PID control, such as P control, PD control, or PI control. By using PID control to realize closed-loop control, it has the advantages of simple algorithm, good robustness, and high reliability.

[0083] It should be understood that in addition to the PID algorithm, the control device 221 may also use other algorithms to control the operating parameters of the return air device 203, the opening of the first control valve 214, and the opening of the second control valve 217, which is not limited herein.

[0084] In addition, in the above-mentioned embodiments of the present disclosure, the exhaust gas from the first heat treatment device 201 or the second heat treatment device 212 can be directly introduced into the first heat treatment device 201 without passing through a heat exchanger, so as to further reduce heat energy loss (for example, due to heat exchange) and reduce system complexity, thereby reducing the cost of waste heat recovery.

[0085] refer to Fig.12 , a block diagram of an exemplary computing device 1000 according to an embodiment of the present disclosure is shown. The computing device 1000 includes at least one processor 1010 and a memory 1020 coupled to the processor 1010. The memory 702 is used to store computer executable instructions, which, when executed, cause the processor 1010 to perform a method according to an embodiment of the present disclosure (e.g., any one or more steps of the aforementioned methods or processes 300, 400, 500, 600, 700, 800, 900).

[0086] In one embodiment, the present disclosure provides a production process system, including a waste heat recovery system according to an embodiment of the present disclosure (for example, Figure 2-Figure 4 Waste heat recovery system 200A-200C) or Fig.12 The computing device 1000. For example, the production processing system further includes a first heat treatment device and a second heat treatment device.

[0087] In addition, alternatively, the above method can be implemented by a computer-readable storage medium. Computer-readable storage media are loaded with computer-readable program instructions for executing various embodiments of the present disclosure. Computer-readable storage media can be a tangible device that can hold and store instructions used by an instruction execution device. Computer-readable storage media can be, for example, but not limited to, electrical storage devices, magnetic storage devices, optical storage devices, electromagnetic storage devices, semiconductor storage devices, or any suitable combination of the above. More specific examples (non-exhaustive lists) of computer-readable storage media include: portable computer disks, hard disks, random access memories (RAM), read-only memories (ROM), erasable programmable read-only memories (EPROM or flash memory), static random access memories (SRAM), portable compact disk read-only memories (CD-ROM), digital versatile disks (DVD), memory sticks, floppy disks, mechanical encoding devices, such as punch cards or protruding structures in grooves on which instructions are stored, and any suitable combination of the above. The computer-readable storage medium used herein is not to be construed as a transient signal per se, such as a radio wave or other freely propagating electromagnetic wave, an electromagnetic wave propagating through a waveguide or other transmission medium (e.g., light pulses through a fiber optic cable), or an electrical signal transmitted through wires.

[0088] Therefore, in another embodiment, the present disclosure provides a computer-readable storage medium having computer-executable instructions stored thereon, where the computer-executable instructions are used to execute the methods in various embodiments of the present disclosure.

[0089] In another embodiment, the present disclosure proposes a computer program product, which includes computer executable instructions. When the computer executable instructions are executed, at least one processor performs the method in various embodiments of the present disclosure.

[0090] In general, various example embodiments of the present disclosure may be implemented in hardware or dedicated circuits, software, firmware, logic, or any combination thereof. Certain aspects may be implemented in hardware, while other aspects may be implemented in firmware or software that may be executed by a controller, microprocessor, or other computing device. When various aspects of the embodiments of the present disclosure are illustrated or described as block diagrams, flow charts, or using some other graphical representation, it will be understood that the blocks, devices, systems, techniques, or methods described herein may be implemented in hardware, software, firmware, dedicated circuits or logic, general hardware or controllers or other computing devices, or some combination thereof as non-limiting examples.

[0091] In addition to being tangibly stored on a computer-readable storage medium, the computer-readable program instructions or computer program products used to execute the various embodiments of the present disclosure can also be stored in the cloud. When needed, users can access the computer-readable program instructions for executing an embodiment of the present disclosure stored in the cloud through mobile Internet, fixed network or other networks, thereby implementing the technical solutions disclosed in accordance with the various embodiments of the present disclosure.

[0092] Although the embodiments of the present disclosure have been described with reference to several specific embodiments, it should be understood that the embodiments of the present disclosure are not limited to the specific embodiments of the disclosed content. The embodiments of the present disclosure are intended to cover various modifications and equivalent arrangements included in the spirit and scope of the appended claims. The scope of the claims is consistent with the broadest interpretation, thereby including all such modifications and equivalent structures and functions.

Claims

1. A waste heat recovery system, characterized in that: include: a first exhaust duct connected to an air outlet of the first heat treatment device and an external space, wherein the first exhaust duct includes a first exhaust device; a first return air duct connected to the first exhaust air duct and a first air inlet among a plurality of air inlets of the first heat treatment device, the first return air duct comprising return air equipment; a second exhaust duct connected to an air outlet of the second heat treatment device and an external space, wherein the second exhaust duct includes a first control valve and a second exhaust device; a second air return duct connected to the second air exhaust duct and a second air inlet among the plurality of air inlets of the first heat treatment device, the second air return duct comprising a second control valve, and the first control valve being disposed between the second air return duct and the external space; Wherein, the temperature of the first return air transmitted through the first return air duct is lower than the temperature of the second return air transmitted through the second return air duct.

2. The waste heat recovery system according to claim 1, characterized in that: Also includes: A control device is operatively coupled to the return air device, the first control valve, and the second control valve, and is configured to adjust the pressure in the first heat treatment device and the pressure in the second return air duct upstream of the second control valve by controlling the return air device, the first control valve, and the second control valve.

3. The waste heat recovery system according to claim 2, characterized in that: The control device is configured to adjust the pressure in the first heat treatment device and the pressure in the second return air duct by controlling the return air device, the first control valve and the second control valve, including: The control device performs closed-loop control on the pressure in the first heat treatment device by controlling at least one of the return air device and the second control valve, so that the pressure in the first heat treatment device is maintained in a first stable range; The control device performs closed-loop control on the pressure in the second return air duct by controlling the first control valve, so that the pressure in the second return air duct is maintained in a second stable range.

4. The waste heat recovery system according to claim 3, characterized in that: The first stable range is a negative pressure value relative to the external air pressure.

5. The waste heat recovery system according to claim 3, characterized in that: The second stable range is a positive pressure value relative to the external air pressure.

6. A waste heat recovery control method, characterized in that: The method is applicable to the waste heat recovery system according to claim 1, and the method comprises: The pressure in the first heat treatment device and the pressure at the upstream of the second control valve in the second return air line are adjusted by controlling the return air device, the first control valve and the second control valve.

7. The waste heat recovery control method according to claim 6, characterized in that: Regulating the pressure in the first heat treatment device and the pressure upstream of the second control valve by controlling the return air device, the first control valve, and the second control valve comprises: Performing closed-loop control on the pressure in the first heat treatment device by controlling at least one of the return air device and the second control valve, so that the pressure in the first heat treatment device is maintained in a first stable range; The pressure in the second return air duct is controlled in a closed loop by controlling the first control valve, so that the pressure upstream of the second control valve is maintained in a second stable range.

8. The waste heat recovery control method according to claim 6, characterized in that: Adjusting the pressure in the first heat treatment device and the pressure in the second return air duct by controlling the return air device, the first control valve, and the second control valve includes: The return air device, the first control valve, and the second control valve are controlled under multiple states of waste heat recovery to adjust the pressure in the first heat treatment device and the pressure in the second return air duct.

9. The waste heat recovery control method according to claim 8, characterized in that: The multiple states of waste heat recovery include a startup state, wherein in the startup state: Initially setting the opening of the second control valve to a first predetermined value; increasing the opening of the second control valve, and performing closed-loop control on the pressure in the first heat treatment device by controlling the operating parameters of the return air device at the opening; If the operating parameter of the return air device drops to the operating threshold, it is determined that the waste heat recovery enters the waste heat stable state and switches to closed-loop control of the pressure in the first heat treatment device by controlling the operating parameter of the second control valve; If the operating parameters of the return air device do not drop to the operating threshold and the opening of the second control valve increases to the opening threshold, it is determined that the waste heat recovery enters the waste heat stable state and the pressure in the first heat treatment device will be closed-loop controlled by controlling the operating parameters of the return air device.

10. The waste heat recovery control method according to claim 9, characterized in that: The plurality of states include a residual heat stable state, wherein in the residual heat stable state: When the pressure in the first heat treatment device is closed-loop controlled by controlling the operating parameters of the return air device, if the change of the pressure in the first heat treatment device relative to the predetermined pressure exceeds the positive limit value, switching to closed-loop control of the pressure in the first heat treatment device by controlling the second control valve, otherwise the closed-loop control of the pressure in the first heat treatment device by controlling the operating parameters of the return air device is maintained; When the pressure in the first heat treatment device is controlled in a closed loop by controlling the operating parameters of the second control valve, if the change of the pressure in the first heat treatment device relative to the predetermined pressure exceeds the negative limit value, the closed loop control of the pressure in the first heat treatment device is switched to controlling the return air device, otherwise the closed loop control of the pressure in the first heat treatment device is maintained by controlling the operating parameters of the second control valve.

11. The waste heat recovery control method according to any one of claims 7 to 10, characterized in that: Also includes: Under the opening degree of the second control valve, obtaining the detection pressure at the upstream of the second control valve; and The pressure upstream of the second control valve is controlled in a closed loop by controlling the first control valve, including: based on the current error between the set pressure and the detection pressure upstream of the second control valve, determining the operating parameters for the first control valve to control the opening of the first control valve.

12. The waste heat recovery control method according to claim 8, characterized in that: The multiple states include a shutdown state, wherein in the shutdown state: gradually reducing the opening of the second control valve until the second control valve is closed, and at the same time performing closed-loop control on the pressure in the first heat treatment device by controlling the operating parameters of the return air device at the opening; The exit performs closed-loop control on the pressure upstream of the second control valve by controlling the first control valve, and opens the opening of the first control valve to a predetermined opening.

13. The waste heat recovery control method according to claim 12, characterized in that: Also includes: When a fault indication about at least one of the first heat treatment device and the second heat treatment device is received and / or an indication about stopping the waste heat recovery is received, the waste heat recovery enters a shutdown state.

14. The waste heat recovery control method according to any one of claims 7 to 10, characterized in that: obtaining a detection pressure in the first heat treatment device; and Performing closed-loop control of the pressure in the first heat treatment device by controlling the return air device includes: determining operating parameters for the return air device to control the air volume of the return air device based on a current error between a set pressure and a detected pressure of the first heat treatment device.

15. The waste heat recovery control method according to any one of claims 7 to 10, characterized in that: obtaining a detection pressure in the first heat treatment device; and Performing closed-loop control on the pressure in the first heat treatment device by controlling the second control valve includes: determining operating parameters for the second control valve to control the opening of the second control valve based on a current error between a set pressure and a detected pressure of the first heat treatment device.

16. The waste heat recovery control method according to any one of claims 7 to 10, characterized in that: The closed-loop control includes PID control, which includes linearly combining the ratio, integration, and differentiation of the current error between the set pressure in the first heat treatment device or upstream of the second control valve and the detection pressure to form a control quantity, and controlling the corresponding controlled objects in the return air equipment, the first control valve, and the second control valve.

17. A computing device, characterized in that include: at least one processor; as well as A memory for storing computer executable instructions, which, when executed, enables the at least one processor to execute the waste heat recovery control method according to any one of claims 6 to 16.

18. A production processing system, characterized in that: include: A waste heat recovery system according to any one of claims 1 to 5 or a computing device according to claim 17.

19. A computer-readable storage medium having computer-executable instructions stored thereon, wherein the computer-executable instructions are used to execute the waste heat recovery control method according to any one of claims 6 to 16. 20 . A computer program product, comprising computer executable instructions, which when executed, enable at least one processor to perform the waste heat recovery control method according to any one of claims 6 to 16.

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