Intermittent high-temperature flue gas waste heat gradient recovery and cascade utilization system and use method

Abstract

The present invention provides an intermittent high-temperature flue gas waste heat gradient recovery and cascade utilization system and a method for use, wherein the system includes an intermittent industrial kiln group, a flue gas waste heat gradient recovery unit, a flue gas heat storage cascade utilization unit, a gradient heat storage unit and an intelligent control unit; the intermittent high-temperature flue gas waste heat gradient recovery and cascade utilization system and a method for use provided by the present invention are intended to solve the existing problem of imbalance in supply and demand of intermittent high-temperature flue gas waste heat in time, space and energy quality.

Description

Technical Field

[0001] The present invention relates to industrial flue gas waste heat recovery and different quality energy heat storage and heat exchange technology, and in particular to an intermittent high-temperature flue gas waste heat gradient recovery and cascade utilization system and a use method. Background Art

[0002] Existing intermittent industrial production processes often lack comprehensive waste heat recovery systems, and the waste heat from high-temperature flue gases generated in most production processes is not fully utilized. Therefore, energy-saving transformation and waste heat recovery in high-energy-consuming industrial production processes are urgently needed.

[0003] As a commonly used high-temperature thermal storage medium, high-temperature molten salt offers numerous advantages, including a wide operating temperature range (150°C-1300°C), low saturated vapor pressure, high safety, large heat storage capacity, excellent chemical stability, and readily available, inexpensive raw materials. It has been widely used in numerous high-temperature thermal storage industries, such as solar thermal storage, solar thermal power generation, and industrial heating. Its high-density thermal storage, safety, and low cost make it ideal for the recovery and storage of high-temperature flue gas waste heat. Furthermore, due to its wide and easily adjustable operating temperature range, it enables gradient recovery and cascade utilization of flue gas waste heat, potentially resolving the current imbalance in the supply and demand of intermittent high-temperature flue gas waste heat in terms of time, space, and energy quality. Summary of the Invention

[0004] The present invention provides an intermittent high-temperature flue gas waste heat gradient recovery and cascade utilization system and a method for use, aiming to solve the problem of imbalance in supply and demand of existing intermittent high-temperature flue gas waste heat in terms of time, space and energy quality.

[0005] To solve the above problems, the present invention provides an intermittent high-temperature flue gas waste heat gradient recovery and cascade utilization system, comprising:

[0006] Intermittent industrial kiln clusters;

[0007] A flue gas waste heat gradient recovery unit includes a flue gas waste heat recovery main circuit and multiple flue gas waste heat recovery units, the flue gas waste heat recovery main circuit is connected to the intermittent industrial kiln group, a fan is provided on the flue gas waste heat recovery main circuit, the fan is used to extract high-temperature flue gas from the intermittent industrial kiln group, each of the flue gas waste heat recovery units includes a flue gas waste heat recovery branch circuit, a heat storage end heat exchanger and a heat storage end electric valve provided on the flue gas waste heat recovery branch circuit, the flue gas waste heat recovery branch circuit is respectively connected to the flue gas waste heat recovery main circuit, and each of the flue gas waste heat recovery units is used to respectively recover flue gas heat of different qualities from the high-temperature flue gas;

[0008] The flue gas heat storage cascade utilization unit includes a plurality of flue gas heat storage utilization units corresponding to the flue gas waste heat recovery units, each of the flue gas heat storage utilization units includes a flue gas heat storage utilization circuit, a driving machine, a heating end electric valve, a check valve, a heating end heat exchanger, a user source, and an internal heat exchange medium provided on the flue gas heat storage utilization circuit, the driving machine being used to drive the internal heat exchange medium to flow in the flue gas heat storage utilization circuit;

[0009] A gradient heat storage unit includes a plurality of gradient heat storage sources corresponding to each of the flue gas waste heat recovery units and each of the flue gas heat storage and utilization units, each of the gradient heat storage sources is provided with a heat storage medium, the operating temperature of each of the heat storage media decreases step by step, and each of the corresponding heat storage end heat exchangers and the corresponding heat supply end heat exchangers are placed in the heat storage medium for heat exchange through the heat storage medium; and

[0010] An intelligent control unit is electrically connected to the fan, each of the heat storage end electric valves, each of the heat supply end electric valves and each of the driving machines, and is used to control the opening and closing of each of the flue gas waste heat recovery branches and each of the flue gas heat storage and utilization circuits, and the operating power of the fan and each of the driving machines according to the working conditions.

[0011] According to an intermittent high-temperature flue gas waste heat gradient recovery and cascade utilization system provided by the present invention, each flue gas waste heat recovery branch is connected through a flue gas waste heat recovery bypass, and each flue gas waste heat recovery bypass is arranged between two adjacent heat storage end heat exchangers.

[0012] According to an intermittent high-temperature flue gas waste heat gradient recovery and cascade utilization system provided by the present invention, each flue gas heat storage utilization circuit is connected through two flue gas heat storage utilization bypasses, and a bypass electric valve is respectively provided on the two flue gas heat storage utilization bypasses.

[0013] According to an intermittent high-temperature flue gas waste heat gradient recovery and cascade utilization system provided by the present invention, the intelligent control unit includes a fluid condition test component and a controller, and the controller is electrically connected to the fluid condition test component, the fan, each of the heat storage end electric valves, each of the heat supply end electric valves, each of the bypass electric valves, and each of the driving motors;

[0014] The fluid operating condition testing component includes a waste heat main circuit temperature transmitter and a waste heat main circuit fluid flow meter provided on the flue gas waste heat recovery main circuit, a heat storage source temperature transmitter provided on each of the gradient heat storage sources, and a heat storage utilization circuit temperature transmitter and a heat storage utilization circuit fluid flow meter provided on each of the flue gas heat storage utilization circuits. The controller is used to control the operating power of the fan and the opening and closing of each of the heat storage end electric valves according to data from the waste heat main circuit temperature transmitter, the waste heat main circuit fluid flow meter and the heat storage source temperature transmitter, and is used to control the operating power of the corresponding driving machine, the opening and closing of the corresponding heating end electric valve and the opening and closing of the corresponding bypass electric valve according to data from the heat storage source temperature transmitter, the heat storage utilization circuit temperature transmitter, the heat storage utilization circuit fluid flow meter and the heating demand of the user source.

[0015] According to an intermittent high-temperature flue gas waste heat gradient recovery and cascade utilization system provided by the present invention, the user source is provided at the inlet branch of the corresponding heat exchanger at the heating end, the driving motor is provided at the outlet branch of the corresponding heat exchanger at the heating end, and the check valve and the heat storage utilization circuit fluid flowmeter are provided at the outlet branch of the heat exchanger at the heating end;

[0016] The heat storage utilization circuit temperature transmitter is arranged upstream of the user source, and the heat storage utilization circuit temperature transmitter, the heating end electric valve and the user source are all arranged on the same branch.

[0017] According to an intermittent high-temperature flue gas waste heat gradient recovery and cascade utilization system provided by the present invention, the gradient heat storage source includes a heat storage tank, a accommodating chamber is provided in the heat storage tank, the heat storage medium is arranged in the accommodating chamber, an insulation layer is provided on the outside of the heat storage tank, and the heat storage source temperature transmitter is arranged in the heat storage medium of the heat storage tank.

[0018] According to an intermittent high-temperature flue gas waste heat gradient recovery and cascade utilization system provided by the present invention, the heat storage medium includes heat storage molten salt, and the gradient heat storage source stores the heat displaced by the heat storage end heat exchanger by means of the sensible heat storage and phase change heat storage methods of the heat storage molten salt.

[0019] According to an intermittent high-temperature flue gas waste heat gradient recovery and cascade utilization system provided by the present invention, the melting point of each of the thermal storage molten salts is lower than the temperature of the corresponding high-temperature flue gas, and the operating upper limit temperature of the thermal storage molten salt is higher than the corresponding high-temperature flue gas temperature.

[0020] According to an intermittent high-temperature flue gas waste heat gradient recovery and cascade utilization system provided by the present invention, the thermal storage molten salt includes multiple salt components, and the operating temperature of the thermal storage molten salt is determined by the ratio of each salt component.

[0021] The present invention further provides a method for using an intermittent high-temperature flue gas waste heat gradient recovery and cascade utilization system, which uses the intermittent high-temperature flue gas waste heat gradient recovery and cascade utilization system as described in any one of the above items, comprising:

[0022] Determine the first functional relationship between exhaust gas temperature and exhaust gas volume of batch industrial furnaces;

[0023] Obtaining the flue gas temperature, and adjusting the fan frequency according to the first functional relationship to control the flue gas flow;

[0024] Obtaining the actual temperature of the heat storage medium of each gradient heat storage source, and determining the opening and closing of each flue gas waste heat recovery branch according to the flue gas temperature and the actual temperature;

[0025] Obtaining the actual temperature of the heat storage medium of each gradient heat storage source and the heating demand of the user source, and determining the opening and closing of each flue gas heat storage and utilization circuit according to the actual temperature and the heating demand;

[0026] Determine the second functional relationship between the temperature, flow rate and heat supply of the internal heat exchange medium in the flue gas heat storage and utilization loop;

[0027] The temperature of the internal heat exchange medium is obtained, and according to the heat supply demand, the second functional relationship and the temperature of the internal heat exchange medium, the frequency of the corresponding driving machine is regulated to adjust the flow rate of the internal heat exchange medium.

[0028] The intermittent high-temperature flue gas waste heat gradient recovery and cascade utilization system provided by the present invention introduces multiple gradient heat storage sources with different operating temperatures that match the heat demand of actual industrial production processes. This achieves gradient recovery of high-temperature flue gas waste heat generated in industrial processes and a cascade utilization process characterized by "high energy, high utilization, low energy, low utilization." This effectively solves the problems of intermittent high-temperature flue gas waste heat in industrial production processes, such as difficulty in recovery, storage, and timely and spatial heating. Simultaneously, the intelligent control unit calculates the optimal heat storage and heating path based on the flue gas temperature, the temperature of the heat storage medium in the gradient heat storage source, and the user source heating demand, thereby achieving high-quality storage and efficient utilization of intermittent flue gas waste heat and promoting low-carbon and energy-saving production in industrial processes. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] In order to more clearly illustrate the technical solutions in the present invention or the prior art, a brief introduction will be given below to the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0030] Figure 1 This is a schematic diagram of the system structure of the intermittent high-temperature flue gas waste heat gradient recovery and cascade utilization system provided by the present invention;

[0031] Figure 2 yes Figure 1 Schematic diagram of the structure of the intelligent control unit.

[0032] Figure numerals: 1: Intermittent high-temperature flue gas waste heat gradient recovery and cascade utilization system; 2: Intermittent industrial kiln group; 3: Waste heat main line fluid flow meter; 4: Waste heat main line temperature transmitter; 5: Fan; 6: Heat storage end electric valve; 7: Gradient heat storage source; 8: Driving machine; 9: Heat storage utilization loop fluid flow meter; 10: Heating end electric valve; 11: Check valve; 12: First bypass electric valve; 13: Second bypass electric valve; 14: Heat storage source temperature transmitter; 15: Heat storage end heat exchanger; 16: Heating end heat exchanger; 17: User source; 18: Heat storage utilization loop temperature transmitter; 19: Intelligent control unit; 20: Flue gas waste heat recovery bypass. DETAILED DESCRIPTION

[0033] To make the objectives, technical solutions, and advantages of the present invention more clear, the technical solutions of the present invention will be clearly and completely described below in conjunction with the accompanying drawings. Obviously, the embodiments described are only some of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts shall fall within the scope of protection of the present invention.

[0034] In the description of the embodiments of the present invention, it should be noted that the terms "center", "longitudinal", "lateral", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", etc., indicating the orientation or positional relationship, are based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing the embodiments of the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operate in a specific orientation, and therefore should not be understood as limiting the embodiments of the present invention. In addition, the terms "first", "second", and "third" are used for descriptive purposes only and should not be understood as indicating or implying relative importance.

[0035] In the description of the embodiments of the present invention, it should be noted that, unless otherwise specified or limited, the terms "connected" and "connection" should be understood in a broad sense. For example, they can refer to fixed connections, detachable connections, or integral connections; mechanical connections, electrical connections; and direct connections or indirect connections through an intermediary. Those skilled in the art will understand the specific meanings of the above terms in the embodiments of the present invention based on the specific circumstances.

[0036] In the embodiments of the present invention, unless otherwise expressly specified or limited, a first feature being "above" or "below" a second feature 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. Furthermore, a first feature being "above," "above," or "above" a second feature may mean that the first feature is directly above or diagonally above the second feature, or simply means that the first feature is at a higher level than the second feature. A first feature being "below," "below," or "below" a second feature may mean that the first feature is directly below or diagonally below the second feature, or simply means that the first feature is at a lower level than the second feature.

[0037] In the description of this specification, the reference terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" mean 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 embodiment of the present invention. In this specification, the schematic representations of the above terms do 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. In addition, those skilled in the art can combine and combine different embodiments or examples described in this specification and features of different embodiments or examples without contradiction.

[0038] The following combination Figure 1 and Figure 2 The present invention describes an intermittent high-temperature flue gas waste heat gradient recovery and cascade utilization system 1 and a method of use.

[0039] Based on the existing industrial production process, the intermittent high-temperature flue gas waste heat generated by the discontinuous production method is difficult to recover and store, and the problem of mismatch with the actual industrial production process heating demand is mentioned. Figure 1-Figure 2 The present invention provides an intermittent high-temperature flue gas waste heat gradient recovery and cascade utilization system 1, the intermittent high-temperature flue gas waste heat gradient recovery and cascade utilization system 1, including an intermittent industrial kiln group 2, a flue gas waste heat gradient recovery unit, a flue gas heat storage cascade utilization unit, a gradient heat storage unit and an intelligent control unit 19.

[0040] Among them, the flue gas waste heat gradient recovery unit includes a flue gas waste heat recovery main circuit and multiple flue gas waste heat recovery parts. The flue gas waste heat recovery main circuit is connected to the intermittent industrial kiln group 2. A fan 5 is provided on the flue gas waste heat recovery main circuit. The fan 5 is used to extract the high-temperature flue gas from the intermittent industrial kiln group 2. Each flue gas waste heat recovery part includes a flue gas waste heat recovery branch circuit, a heat storage end heat exchanger 15 provided on the flue gas waste heat recovery branch circuit, and a heat storage end electric valve 6. The flue gas waste heat recovery branch circuits are respectively connected to the flue gas waste heat recovery main circuit. Driven by the fan 5, the intermittent high-temperature flue gas flows out through the exhaust port of the intermittent industrial kiln group 2 and flows into the flue gas waste heat recovery branches of each level. The heat of the flue gas in the corresponding level of flue gas waste heat recovery branch circuit is recovered through the heat storage end heat exchanger 15 and stored in the gradient heat storage unit.

[0041] The flue gas heat storage cascade utilization unit includes a plurality of flue gas heat storage utilization units corresponding to the respective flue gas waste heat recovery units. Each flue gas heat storage utilization unit includes a flue gas heat storage utilization circuit, a driving machine 8, a heating end electric valve 10, a check valve 11, a heating end heat exchanger 16, a user source 17, and an internal heat exchange medium provided on the flue gas heat storage utilization circuit. The driving machine 8 is used to drive the internal heat exchange medium to flow in the flue gas heat storage utilization circuit and provide heat to the user source 17.

[0042] The gradient heat storage unit includes a plurality of gradient heat storage sources 7 corresponding to each flue gas waste heat recovery unit and each flue gas heat storage and utilization unit. Each gradient heat storage source 7 is provided with a heat storage medium. The operating temperature of each heat storage medium decreases step by step. Each corresponding heat storage end heat exchanger 15 and corresponding heat supply end heat exchanger 16 are placed in the heat storage medium. Heat is transferred from the heat storage end heat exchanger 15 to the heat supply end heat exchanger 16 through the heat storage medium to achieve heat conversion and utilization.

[0043] The intelligent control unit 19 is electrically connected to the fan 5, each heat storage end electric valve 6, each heat supply end electric valve 10 and each driver 8, and is used to control the opening and closing of each flue gas waste heat recovery branch and each flue gas heat storage and utilization circuit, and the operating power of the fan 5 and each driver 8 according to the working conditions.

[0044] The intermittent high-temperature flue gas waste heat gradient recovery and cascade utilization system 1 provided by the present invention introduces multiple gradient heat storage sources 7 with different operating temperatures that match the heat demand in actual industrial production processes. This achieves gradient recovery of high-temperature flue gas waste heat generated in industrial processes and a "high-energy, high-use, low-energy, low-use" cascade utilization process. This effectively solves the problems of intermittent high-temperature flue gas waste heat in industrial production processes, such as difficulty in recovery, storage, and timely and spatial heating. Simultaneously, the intelligent control unit 19 calculates the optimal heat storage and heating path based on the flue gas temperature, the temperature of the gradient heat storage source 7, and the heating demand of the user source 17, thereby achieving high-quality storage and efficient utilization of intermittent flue gas waste heat and promoting low-carbon and energy-saving production in industrial processes.

[0045] Specifically, each flue gas waste heat recovery branch is connected through a flue gas waste heat recovery bypass 20, and each flue gas waste heat recovery bypass 20 is provided between two adjacent heat storage end heat exchangers 15. It should be noted that the working temperature of the gradient heat storage source 7 is set to decrease step by step, and the high-temperature flue gas preferentially flows into the gradient heat storage source 7 with a matching working temperature, and then flows to the next level gradient heat storage source 7 through the flue gas waste heat recovery bypass 20 in turn. The temperature of the high-temperature flue gas drops after each heat exchange process until the last level gradient heat storage source 7 absorbs the remaining low-grade heat energy of the flue gas with the help of the heat storage medium with a low working temperature and discharges it to the outdoor environment, thereby realizing the step-by-step storage and transmission of flue gas waste heat according to the energy quality. You can refer to Figure 1 There are multiple flue gas waste heat recovery branches, gradient heat storage sources 7 and flue gas heat storage utilization parts. The specific number can be set according to the number of kilns in the intermittent industrial kiln group 2 or the supply and demand requirements of the user source 17. The present invention does not limit this.

[0046] Furthermore, each flue gas thermal storage and utilization circuit is connected through two flue gas thermal storage and utilization bypasses, and each of the two flue gas thermal storage and utilization bypasses is provided with a bypass electric valve. As mentioned above, the high-temperature flue gas preferentially flows into the gradient thermal storage source 7 with a matching operating temperature, and then sequentially flows through the flue gas waste heat recovery bypass 20 to the next-level gradient thermal storage source 7. Correspondingly, if the operating condition of the gradient thermal storage source 7 meets the heating demand of the user source 17 in the corresponding flue gas thermal storage and utilization circuit, the gradient thermal storage source 7 first supplies heat to the corresponding flue gas thermal storage and utilization circuit. If the operating condition of the gradient thermal storage source 7 does not meet the heating demand of the user source 17 in the corresponding flue gas thermal storage and utilization circuit, the first bypass electric valve 12 and the second bypass electric valve 13 are opened, and the gradient thermal storage source 7 preferentially supplies heat to the user source 17 in the next-level flue gas thermal storage and utilization circuit through the flue gas thermal storage and utilization bypass.

[0047] Specifically, the intelligent control unit 19 includes a fluid working condition test component and a controller. The controller is electrically connected to the fluid working condition test component, the fan 5, each heat storage end electric valve 6, each heat supply end electric valve 10, each bypass electric valve and each driver 8; the fluid working condition test component includes a waste heat main road temperature transmitter 4 and a waste heat main road flue gas flowmeter 3 provided on the flue gas waste heat recovery main road, a heat storage source temperature transmitter 14 provided on each gradient heat storage source 7, and a heat storage utilization circuit temperature transmitter 18 and a heat storage utilization circuit fluid flowmeter 9 provided on each flue gas heat storage utilization circuit. The controller is used to detect the residual heat in the flue gas waste heat recovery main road. The data from the main temperature transmitter 4 and the waste heat main fluid flowmeter 3 control the operating power of the fan 5 and the opening and closing of each heat storage end electric valve 6, so as to control the operating power of the corresponding driving machine 8, the opening and closing of the corresponding heating end electric valve 10 and the opening and closing of the corresponding bypass electric valve according to the data from the heat storage source temperature transmitter 14, the heat storage utilization loop temperature transmitter 18, the heat storage utilization loop fluid flowmeter 9 and the heating demand of the user source 17. The specific operation method of the intelligent control unit 19 will be described in detail with reference to the following method of using the intermittent high-temperature flue gas waste heat gradient recovery and cascade utilization system 1.

[0048] In the technical solution provided by the present invention, please refer to Figure 1 The user source 17 is arranged at the inlet branch of the corresponding heat exchanger 16 at the heating end, the driving machine 8 is arranged at the outlet branch of the corresponding heat exchanger 16 at the heating end, the check valve 11 and the heat storage utilization loop fluid flowmeter 9 are arranged at the outlet branch of the heat exchanger 16 at the heating end, the heat storage utilization loop temperature transmitter 18 is arranged upstream of the user source 17, and the heat storage utilization loop temperature transmitter 18, the heating end electric valve 10 and the user source 17 are all arranged on the same branch.

[0049] Specifically, the gradient heat storage source 7 includes a heat storage tank, a storage cavity is provided in the heat storage tank, a heat storage medium is provided in the storage cavity, an insulation layer is provided outside the heat storage tank, and a heat storage source temperature transmitter 14 is provided in the heat storage tank. The insulation layer is used to prevent heat loss. The heat storage medium can be a substance with a large specific heat capacity, preferably a substance that can produce a phase change within the temperature range of the flue gas, so that the maximum range of heat storage can be achieved. In the technical solution provided by the present invention, the heat storage medium includes but is not limited to heat storage molten salt, and the gradient heat storage source 7 uses the explicit heat storage and phase change heat storage methods of the heat storage molten salt to store the heat displaced by the corresponding heat storage heat exchanger.

[0050] It should be noted that the melting point of the thermal storage molten salt must be lower than the temperature of the high-temperature flue gas, and the upper limit temperature of the thermal storage molten salt must be higher than the temperature of the high-temperature flue gas. In the early stage of heat exchange, the temperature of the thermal storage molten salt continues to rise as the heat exchange proceeds; when the temperature reaches the melting point of the thermal storage molten salt, the thermal storage molten salt begins to undergo a phase change until all the thermal storage molten salt in the thermal storage tank melts into a liquid; at the end of the heat exchange, the temperature of the thermal storage molten salt continues to rise as the heat exchange proceeds. The gradient thermal storage source 7 uses the two heat storage methods of thermal storage molten salt explicit heat storage and phase change heat storage to store the waste heat of the high-temperature flue gas within the corresponding molten salt heat storage operating temperature range, and provides a heat source during the heating period of the user source 17, thereby realizing the staggered time and space utilization of the waste heat of the high-temperature flue gas. It should be noted that thermal storage molten salt includes multiple salt components. The operating temperature of thermal storage molten salt is determined by the ratio of each salt component. The salt component ratio can be adjusted accordingly according to the different melting points and upper working limit temperatures of different salt components, so that the melting point of thermal storage molten salt is lower than the high-temperature flue gas temperature and the upper working limit temperature is higher than the corresponding high-temperature flue gas temperature.

[0051] Furthermore, the present invention also provides a method for using the intermittent high-temperature flue gas waste heat gradient recovery and cascade utilization system 1, which uses the intermittent high-temperature flue gas waste heat gradient recovery and cascade utilization system 1 as described above, comprising:

[0052] S100, determining a first functional relationship between exhaust gas temperature and exhaust gas volume of a batch industrial furnace group;

[0053] S200, obtaining the flue gas temperature, and adjusting the fan frequency according to the first functional relationship to control the flue gas flow;

[0054] S300, obtaining the actual temperature of the heat storage medium of each gradient heat storage source, and determining whether to open or close each flue gas waste heat recovery branch according to the flue gas temperature and the actual temperature;

[0055] S400: Acquire the actual temperature of the heat storage medium of each gradient heat storage source and the heating demand of the user source, and determine whether to open or close each flue gas heat storage and utilization circuit according to the actual temperature and the heating demand;

[0056] S500, determining a second functional relationship among the temperature, flow rate, and heat supply of the internal heat exchange medium in the flue gas heat storage and utilization loop;

[0057] S600: Acquire the temperature of the internal heat exchange medium, and adjust the frequency of the corresponding driving machine to adjust the flow rate of the internal heat exchange medium according to the heating demand, the second functional relationship, and the temperature of the internal heat exchange medium.

[0058] Generally speaking, the firing temperature of industrial kilns (flue gas temperature T0) It is positively correlated with the flue gas volume. To ensure the normal production of the industrial kiln cluster, the flue gas generated must be discharged in a timely manner and cannot accumulate. First, the exhaust temperature and exhaust volume data can be obtained multiple times during the production process. The first functional relationship between the exhaust temperature and exhaust volume of the intermittent industrial kiln cluster 2 can be determined based on parameter fitting and stored in the controller. Secondly, the main line temperature transmitter 4 can be used to obtain the flue gas temperature in real time through waste heat. The fan 5 frequency is automatically adjusted based on the first functional relationship and the flue gas temperature to control the flue gas flow, thereby ensuring the normal production of the industrial kiln cluster.

[0059] Assume that i In the heat storage circuit ( i =1, 2, 3… n 、 n +1) User Source M i The minimum required temperature is t I , user source M i The corresponding internal heat exchange medium temperature in the flue gas heat storage and utilization circuit is T , user source M i The actual temperature of the heat storage medium in the flue gas heat storage and utilization circuit is T i , the upper limit working temperature of the heat storage medium is T i，max , user source M i The minimum heat exchange temperature difference between the corresponding flue gas heat storage and utilization loop and the gradient heat storage source 7 is ∆ T i In the method of use provided by the present invention, the waste heat of high-temperature flue gas is stored in a gradient heat storage source 7 with different working temperatures in accordance with the principle of "high energy, high storage; low energy, low storage".

[0060] In the technical solution provided by the present invention, it is necessary to obtain the actual temperature of each heat storage medium, and determine the opening and closing of each flue gas waste heat recovery branch based on the flue gas temperature and the actual temperature of the heat storage medium. The specific method of using the flue gas waste heat gradient recovery unit is as follows:

[0061] When the high temperature flue gas temperature T 0 is greater than i Actual temperature of heat storage medium in step gradient heat storage source 7 T i (actual temperature), the intelligent control unit 19 automatically opens the corresponding i Electric valve A at the heat storage end of the secondary flue gas waste heat recovery branch i The electric valve 6 at the heat storage end of the other level flue gas waste heat recovery branch is automatically closed, and the high temperature flue gas is automatically iThe step gradient heat storage source 7 utilizes the flue gas waste heat to bypass and flows through each downstream gradient heat storage source 7 step by step to store heat, and then discharges it into the atmosphere. i The minimum value is given priority. For example, when T 0 is greater than T 1 and T 2. The high-temperature flue gas flows from the first-stage heat storage unit through the downstream heat storage units step by step to store heat, thereby realizing the expansion of the heat storage capacity while improving the heat storage quality.

[0062] In order to prevent the thermal storage medium of each gradient thermal storage source 7 from exceeding the operating temperature range during the thermal storage process, which may lead to overheating of the molten salt and high-pressure boiling, the intelligent control unit 19 automatically monitors the actual operating temperature of the thermal storage medium of each gradient thermal storage source 7 through the thermal storage source temperature transmitter 14. T i ,when T i Exceeding the upper limit of the working temperature of the heat storage medium T i，max When the intelligent control unit 19 controller automatically turns off the corresponding i Electric valve A on the secondary flue gas waste heat recovery branch i , and open the i + Electric valve A on the 1st stage flue gas waste heat recovery branch i+1 , guiding the flue gas directly into i +1 gradient heat storage source 7 performs heat storage.

[0063] In the technical solution provided by the present invention, flue gas thermal storage follows the principle of "high energy, high utilization, low energy, low utilization" and is preferentially allocated to user sources 17 with different energy quality heating needs. It is necessary to obtain the actual temperature of each thermal storage medium and the heating demand of the user source 17. The opening and closing of each flue gas thermal storage utilization circuit is determined based on the actual temperature of the thermal storage medium and the heating demand. The method of using the thermal storage cascade utilization system is as follows:

[0064] When the gradient heat storage source i Medium heat storage medium temperature T i (Actual temperature) is greater than user source M i Minimum required temperature t I +∆ T i When the gradient heat storage source i The heat storage is supplied first to the i Level User Source M i At this time, the intelligent control unit automatically opens the heating end electric valve B on the flue gas heat storage and utilization circuit i , and automatically adjust the drive F i The power maintains the temperature of the heat exchange medium in the circuit T In user source Mi Heating demand temperature range.

[0065] It should be noted that, similar to the process of obtaining the first functional relationship, the second functional relationship of the temperature, flow rate, and heat supply of the internal heat exchange medium in the flue gas thermal storage and utilization circuit is first determined. During the operation of the flue gas thermal storage and utilization circuit, by obtaining the temperature of the internal heat exchange medium, the frequency of the corresponding driving machine 8 can be adjusted to adjust the flow rate of the internal heat exchange medium according to the heating demand, the second functional relationship, and the temperature of the internal heat exchange medium. Specifically, when the temperature of the internal heat exchange medium is lower than the user source M i Heating demand temperature range, appropriately reduce the driving machine F i The power is used to reduce the heat exchange medium flow rate to increase the heat exchange medium temperature. When the internal heat exchange medium temperature exceeds the user source M i Heating demand temperature range, appropriately increase the drive F i The power is increased to increase the flow rate of heat exchange medium to reduce the temperature of heat exchange medium. At this time, the heat exchange medium i The secondary flue gas heat storage and utilization loop circulates and continuously provides users with M i Heating.

[0066] Furthermore, when the gradient heat storage source i Medium heat storage medium temperature T i Less than user source M i Minimum required temperature t I +∆ T i When the gradient heat storage source i Heat storage is supplied to i +1 level user source M i+1 , as a gradient heat storage source i +1 supplementary heat storage source. At this time, the intelligent control unit 19 automatically closes the heating end electric valve B on the flue gas heat storage utilization circuit. i , open the two bypass electric valves C connected to the next gradient heat storage source 7 i and D i and user source M i+1 Electric valve B at the downstream heating end i+1 , and automatically adjust the drive F i Temperature of internal heat exchange medium in power maintenance circuit T In user source M i+1 Within the heating demand temperature range, that is, when the internal heat exchange medium temperature is lower than the user source M i+1 Heating demand temperature range, appropriately reduce the driving machine F i The power is used to reduce the internal heat exchange medium flow rate to increase the heat exchange medium temperature; when the internal heat exchange medium temperature exceeds the user source M i+1Heating demand temperature range, appropriately increase the drive F i The power of the heat exchange medium is increased to increase the flow rate of the heat exchange medium and reduce the temperature of the heat exchange medium. i and i +1 level gradient heat storage source composed of flue gas heat storage and utilization loop circulates, continuously providing user source M i+1 Heating.

[0067] Furthermore, if the gradient heat storage source i +1 medium heat storage medium temperature T i+1 Continue to be consumed until it is less than the user source M i+1 Minimum required temperature t I+1 +∆ T i+1 When the gradient heat storage source i +1 heat storage is supplied to i +2-level flue gas heat storage utilization unit user source M i+2 , as a gradient heat storage source i +2 supplementary heat storage source. At this time, the intelligent control unit 19 closes the heating end electric valve B on the flue gas heat storage and utilization circuit. i+1 , open the bypass electric valve C connected to the next gradient heat storage source i+1 and D i+1 and user source M i+2 Electric valve B at the downstream heating end i+2 , and automatically adjust the drive F i Temperature of heat exchange medium in power maintenance circuit T In user source M i+2 The heat supply demand temperature range is kept within this cycle until the user source 17 in the last stage of the flue gas heat storage utilization loop consumes all the available heat in the gradient heat storage source 7, and the entire heat exchange process stops. It should be noted that if the temperature of the heat storage medium in the gradient heat storage source T i Greater than user source M i Minimum required temperature t I +∆ T i , but user source M i The maximum heating demand has been reached, then the gradient heat storage source i The stored waste heat can be used by the user source 17 in the downstream flue gas heat storage and utilization unit in the same manner as described above.

[0068] The intermittent high-temperature flue gas waste heat gradient recovery and cascade utilization system 1 provided by the present invention cleverly utilizes the adjustability of the heat storage medium's operating temperature to match the heat quality requirements of the user source 17. This enables the gradient recovery of medium- and high-temperature flue gas waste heat generated during the industrial kiln firing process, as well as the cascade utilization of flue gas heat storage, achieving "high energy, high storage; low energy, low storage" and "high energy, high utilization; low energy, low utilization." This invention is expected to address the challenges of waste heat recovery, storage, and stable heat supply from unstable heat sources such as high-temperature flue gas, and meet the staggered time and space requirements and varying energy quality requirements of actual production processes.

[0069] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the various embodiments of the present invention.

Claims

1. An intermittent high-temperature flue gas waste heat gradient recovery and cascade utilization system, characterized in that: include: Intermittent industrial kiln clusters; A flue gas waste heat gradient recovery unit includes a flue gas waste heat recovery main circuit and multiple flue gas waste heat recovery units, the flue gas waste heat recovery main circuit is connected to the intermittent industrial kiln group, a fan is provided on the flue gas waste heat recovery main circuit, the fan is used to extract high-temperature flue gas from the intermittent industrial kiln group, each of the flue gas waste heat recovery units includes a flue gas waste heat recovery branch circuit, a heat storage end heat exchanger and a heat storage end electric valve provided on the flue gas waste heat recovery branch circuit, the flue gas waste heat recovery branch circuit is respectively connected to the flue gas waste heat recovery main circuit, and each of the flue gas waste heat recovery units is used to respectively recover flue gas heat of different qualities from the high-temperature flue gas; The flue gas heat storage cascade utilization unit includes a plurality of flue gas heat storage utilization units corresponding to the flue gas waste heat recovery units, each of the flue gas heat storage utilization units includes a flue gas heat storage utilization circuit, a driving machine, a heating end electric valve, a check valve, a heating end heat exchanger, a user source, and an internal heat exchange medium provided on the flue gas heat storage utilization circuit, the driving machine being used to drive the internal heat exchange medium to flow in the flue gas heat storage utilization circuit; A gradient heat storage unit includes a plurality of gradient heat storage sources corresponding to each of the flue gas waste heat recovery units and each of the flue gas heat storage and utilization units, each of the gradient heat storage sources is provided with a heat storage medium, the operating temperature of each of the heat storage media decreases step by step, and each of the corresponding heat storage end heat exchangers and the corresponding heat supply end heat exchangers are placed in the heat storage medium for heat exchange through the heat storage medium; and an intelligent control unit, electrically connected to the fan, each of the heat storage end electric valves, each of the heat supply end electric valves, and each of the driving motors, for controlling the opening and closing of each of the flue gas waste heat recovery branches and each of the flue gas heat storage and utilization circuits, and the operating power of the fan and each of the driving motors according to operating conditions; Each of the flue gas waste heat recovery branches is connected via a flue gas waste heat recovery bypass, and each of the flue gas waste heat recovery bypasses is provided between two adjacent heat storage end heat exchangers; Each of the flue gas heat storage and utilization circuits is connected through two flue gas heat storage and utilization bypasses, and a bypass electric valve is respectively provided on the two flue gas heat storage and utilization bypasses.

2. The intermittent high-temperature flue gas waste heat gradient recovery and cascade utilization system according to claim 1 is characterized in that: The intelligent control unit includes a fluid working condition test component and a controller, and the controller is electrically connected to the fluid working condition test component, the fan, each of the heat storage end electric valves, each of the heat supply end electric valves, each of the bypass electric valves and each of the driving machines; The fluid operating condition testing component includes a waste heat main circuit temperature transmitter and a waste heat main circuit fluid flow meter provided on the flue gas waste heat recovery main circuit, a heat storage source temperature transmitter provided on each of the gradient heat storage sources, and a heat storage utilization circuit temperature transmitter and a heat storage utilization circuit fluid flow meter provided on each of the flue gas heat storage utilization circuits. The controller is used to control the operating power of the fan and the opening and closing of each of the heat storage end electric valves according to data from the waste heat main circuit temperature transmitter, the waste heat main circuit fluid flow meter and the heat storage source temperature transmitter, and is used to control the operating power of the corresponding driving machine, the opening and closing of the corresponding heating end electric valve and the opening and closing of the corresponding bypass electric valve according to data from the heat storage source temperature transmitter, the heat storage utilization circuit temperature transmitter, the heat storage utilization circuit fluid flow meter and the heating demand of the user source.

3. The intermittent high-temperature flue gas waste heat gradient recovery and cascade utilization system according to claim 2 is characterized in that: The user source is provided at the inlet branch of the corresponding heat exchanger at the heating end, the driving machine is provided at the outlet branch of the corresponding heat exchanger at the heating end, and the check valve and the heat storage utilization loop fluid flow meter are provided at the outlet branch of the heat exchanger at the heating end; The heat storage utilization circuit temperature transmitter is arranged upstream of the user source, and the heat storage utilization circuit temperature transmitter, the heating end electric valve and the user source are all arranged on the same branch.

4. The intermittent high-temperature flue gas waste heat gradient recovery and cascade utilization system according to claim 2 is characterized in that: The gradient heat storage source includes a heat storage tank, a receiving cavity is provided in the heat storage tank, the heat storage medium is provided in the receiving cavity, an insulation layer is provided outside the heat storage tank, and the heat storage source temperature transmitter is provided in the heat storage medium.

5. The intermittent high-temperature flue gas waste heat gradient recovery and cascade utilization system according to claim 4 is characterized in that: The heat storage medium includes heat storage molten salt, and the gradient heat storage source stores the heat displaced by the heat storage end heat exchanger by means of the sensible heat storage and phase change heat storage methods of the heat storage molten salt.

6. The intermittent high-temperature flue gas waste heat gradient recovery and cascade utilization system according to claim 5 is characterized in that: The melting point of each of the thermal storage molten salts is lower than the temperature of the corresponding high-temperature flue gas, and the upper limit operating temperature of the thermal storage molten salt is higher than the temperature of the corresponding high-temperature flue gas.

7. The intermittent high-temperature flue gas waste heat gradient recovery and cascade utilization system according to claim 5 is characterized in that: The thermal storage molten salt includes multiple salt components, and the operating temperature of the thermal storage molten salt is determined by the ratio of each salt component.

8. A method for using an intermittent high-temperature flue gas waste heat gradient recovery and cascade utilization system, using the intermittent high-temperature flue gas waste heat gradient recovery and cascade utilization system according to any one of claims 1 to 7, characterized in that: include: Determine the first functional relationship between exhaust gas temperature and exhaust gas volume of batch industrial furnaces; Obtaining the flue gas temperature, and adjusting the fan frequency according to the first functional relationship to control the flue gas flow; Obtaining the actual temperature of the heat storage medium of each gradient heat storage source, and determining the opening and closing of each flue gas waste heat recovery branch according to the flue gas temperature and the actual temperature; Obtaining the actual temperature of the heat storage medium of each gradient heat storage source and the heating demand of the user source, and determining the opening and closing of each flue gas heat storage and utilization circuit according to the actual temperature and the heating demand; Determine the second functional relationship between the temperature, flow rate and heat supply of the internal heat exchange medium in the flue gas heat storage and utilization loop; The temperature of the internal heat exchange medium is obtained, and according to the heat supply demand, the second functional relationship and the temperature of the internal heat exchange medium, the frequency of the corresponding driving machine is regulated to adjust the flow rate of the internal heat exchange medium.

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