Fused salt heat storage heating system for intermittent high-temperature flue gas waste heat recovery

Abstract

The application provides a molten salt heat storage and heat supply system for intermittent high-temperature flue gas waste heat recovery, comprising: an intermittent industrial kiln; a high-temperature flue gas waste heat recovery unit comprising a flue gas waste heat recovery pipeline, a fan, a first heat exchanger and a flue gas purifier; a flue gas waste heat utilization unit comprising a flue gas waste heat utilization loop, an internal heat exchange medium, a driving machine, a second heat exchanger and a user source; a heat storage source, the heat storage source being provided with a heat storage medium, the first heat exchanger and the second heat exchanger being arranged in the heat storage medium and used for heat exchange through the heat storage medium; and an intelligent control unit electrically connected with the fan and the driving machine and used for controlling the operating power of the fan and the driving machine according to the working condition. The system aims to solve the problems of difficult recovery, difficult storage and difficult reuse of high-temperature flue gas waste heat generated in the production process of the existing intermittent industrial kiln due to the intermittent production mode, unbalanced energy quality and high impurity content of the flue gas.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of high-temperature intermittent flue gas waste heat storage and recycling equipment, and particularly relates to a molten salt heat storage and heat supply system for intermittent high-temperature flue gas waste heat recovery. BACKGROUND

[0002] The ceramic industry has been labeled as a high-energy-consumption and high-pollution industry due to its own particularity of production. The energy utilization rate of the existing ceramic production process is relatively low, and most of the waste heat is not fully recycled and is directly discharged. This phenomenon is common in intermittent ceramic industrial kilns, especially in industrial kilns under the small workshop production mode. The firing process of intermittent industrial kilns is different from the continuous firing method of roller kilns. The high-temperature waste heat of the firing process cannot be directly utilized in the production links such as body drying and kiln preheating due to the intermittent production mode. Most intermittent ceramic industrial kilns lack a complete and systematic waste heat recovery system, and the high-temperature flue gas waste heat in the firing process of ceramic products often only undergoes simple combustion-supporting air preheating or even is discharged with an open flame without any recycling measures. Although the application of intelligent control technology in intermittent industrial kilns has improved the fuel combustion efficiency and energy utilization rate to some extent, it still cannot change the high energy consumption problem in the production process of ceramic products.

[0003] Exploring the key technology of high-efficiency recovery of high-temperature flue gas waste heat in intermittent ceramic industrial kilns has important theoretical and practical guiding significance for realizing low-carbon and energy-saving intermittent ceramic industrial kilns, and provides a new idea for the energy upgrading and green and energy-saving production of high-energy-consumption ceramic industry. At the same time, it is also the only way for traditional intermittent kilns to seek healthy and sustainable development under the production concept of low-carbon and green in the new era. SUMMARY

[0004] The present application provides a molten salt heat storage and heat supply system for intermittent high-temperature flue gas waste heat recovery, which aims to solve the problems of difficult recovery, difficult storage and difficult recycling of high-temperature flue gas waste heat generated in the production process of existing intermittent ceramic industrial kilns due to intermittent production mode, unbalanced energy quality and high impurity content in flue gas.

[0005] To solve the above problems, the present application provides a molten salt heat storage and heat supply system for intermittent high-temperature flue gas waste heat recovery, which comprises:

[0006] an intermittent industrial kiln;

[0007] a high-temperature flue gas waste heat recovery unit, comprising a flue gas waste heat recovery pipeline, a fan arranged on the flue gas waste heat recovery pipeline and a first heat exchanger, the flue gas waste heat recovery pipeline being in communication with the intermittent industrial kiln, the fan being used for extracting high-temperature flue gas in the intermittent industrial kiln, and the first heat exchanger being used for recovering heat in the high-temperature flue gas;

[0008] The flue gas waste heat utilization unit comprises a flue gas waste heat utilization loop, a driving machine, a second heat exchanger, a user source and an internal heat exchange medium, and the driving machine is used for driving the internal heat exchange medium to flow in the flue gas waste heat utilization loop.

[0009] A heat storage source is internally provided with a heat storage medium, and the first heat exchanger and the second heat exchanger are both arranged in the heat storage medium and used for heat exchange through the heat storage medium.

[0010] An intelligent control unit is electrically connected with the fan and the driving machine and used for controlling the operating power of the fan and the driving machine according to working conditions.

[0011] According to the application, the intelligent control unit comprises a fluid working condition testing component and a controller, and the controller is electrically connected with the fluid working condition testing component, the fan and the driving machine.

[0012] The fluid working condition testing component comprises a first temperature transmitter arranged in the intermittent industrial kiln, a second temperature transmitter arranged in the flue gas waste heat utilization loop, a first flow meter arranged in the flue gas waste heat recovery pipeline and a second flow meter arranged in the flue gas waste heat utilization loop, and the controller is used for controlling the operating power of the fan according to the data of the first temperature transmitter and the first flow meter and for controlling the operating power of the driving machine according to the data of the second temperature transmitter, the second flow meter and the heat supply demand of the user source.

[0013] According to the application, the second temperature transmitter and the second flow meter are arranged downstream of the second heat exchanger.

[0014] According to the application, the heat storage source comprises a heat storage tank, the heat storage tank is internally provided with a containing cavity, the heat storage medium is arranged in the containing cavity, and the heat storage tank is externally provided with a heat preservation layer.

[0015] According to the application, the heat storage medium comprises heat storage molten salt, and the heat storage source stores the heat replaced by the first heat exchanger through explicit heat storage and phase change heat storage of the heat storage molten salt.

[0016] The application provides a molten salt heat storage and supply system for intermittent high-temperature flue gas waste heat recovery.

[0017] The application provides a molten salt heat storage and supply system for intermittent high-temperature flue gas waste heat recovery.

[0018] The application provides a molten salt heat storage and supply system for intermittent high-temperature flue gas waste heat recovery.

[0019] The application provides a molten salt heat storage and supply system for intermittent high-temperature flue gas waste heat recovery.

[0020] The application provides a molten salt heat storage and supply system for intermittent high-temperature flue gas waste heat recovery. BRIEF DESCRIPTION OF DRAWINGS

[0021] In order to more clearly illustrate the technical solutions in the application or prior art, the following will briefly introduce the drawings needed to be used in the embodiments or prior art description. Obviously, the drawings in the following description are some embodiments of the application, and other drawings can be obtained by those skilled in the art without any creative effort on the basis of these drawings.

[0022] Figure 1 Fig. 1 is a structural schematic diagram of the molten salt heat storage and supply system for intermittent high-temperature flue gas waste heat recovery provided by the application.

[0023] Figure 2 Fig. 2 is a schematic diagram of the relationship between the unit mass salt bath heat storage amount of the heat storage source in Fig. 1 and time. Figure 1

[0024] ​Mark No. 1: molten salt heat storage heat supply system for intermittent high-temperature flue gas waste heat recovery; 2: intermittent industrial kiln; 3: high-temperature flue gas waste heat recovery unit; 4: flue gas waste heat utilization unit; 5: heat storage source; 6: intelligent regulation and control unit; 7: flue gas waste heat recovery pipeline; 8: fan; 9: first heat exchanger; 10: flue gas purifier; 11: flue gas waste heat utilization circuit; 12: driving machine; 13: second heat exchanger; 14: user source; 15: heat storage medium; 16: heat storage tank; 17: fluid working condition test component; 18: controller; 19: first temperature transmitter; 20: second temperature transmitter; 21: first flowmeter; 22: second flowmeter; 23: third temperature transmitter. DETAILED DESCRIPTION

[0025] To make the objectives, technical solutions and advantages of the present application clearer, the technical solutions in the present application will be described below in connection with the drawings in the present application. Obviously, the described embodiments are only some of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without any creative effort belong to the scope of protection of the present application.

[0026] In the description of the embodiments of the present application, it should be noted that the orientations or positional relationships indicated by the terms "center", "longitudinal", "lateral", "upper", "lower", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer" and the like are based on the orientations or positional relationships shown in the drawings, and are only for the convenience of describing the embodiments of the present application and simplifying the description, and therefore cannot be understood as indicating or implying that the devices or elements indicated thereby must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as a limitation on the embodiments of the present application. In addition, the terms "first", "second", "third" are only for the purpose of description, and cannot be understood as indicating or implying relative importance.

[0027] In the description of the embodiments of the present application, it should be noted that, unless otherwise explicitly specified and limited, the terms "connected", "connected" should be understood broadly, for example, can be fixedly connected, can be detachably connected, or integrally connected; can be mechanically connected, or electrically connected; can be directly connected, or indirectly connected through an intermediate medium. For those of ordinary skill in the art, the specific meanings of the above terms in the embodiments of the present application can be understood according to the specific circumstances.

[0028] In the embodiments of the present application, unless otherwise explicitly specified and limited, the first feature is "on" or "under" the second feature, which can be that the first and second features are in direct contact, or the first and second features are in indirect contact through an intermediate medium. Moreover, the first feature can be "above", "over" and "on" the second feature, which can be that the first feature is directly above or obliquely above the second feature, or only means that the horizontal height of the first feature is higher than that of the second feature. The first feature can be "below", "under" and "underneath" the second feature, which can be that the first feature is directly below or obliquely below the second feature, or only means that the horizontal height of the first feature is less than that of the second feature.

[0029] In the description of the present application, the description of the terms "one embodiment", "some embodiments", "an example", "a specific example" or "some examples" and the like means that the specific features, structures, materials or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the embodiments of the present application. In the present application, the illustrative description of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any suitable manner in any one or more embodiments or examples. In addition, the skilled in the art can combine and combine the different embodiments or examples described in the present application and the features of the different embodiments or examples without contradiction.

[0030] The present application is described below in conjunction with Figure 1 and Figure 2 The present application provides a molten salt heat storage and heat supply system 1 for intermittent high-temperature flue gas waste heat recovery.

[0031] The existing intermittent industrial kiln production process generates high-temperature flue gas waste heat, which is difficult to recover, store and reuse due to intermittent production mode, unbalanced energy quality and high impurity content in flue gas. In view of this, please refer to Figure 1 The present application provides a molten salt heat storage and heat supply system 1 for intermittent high-temperature flue gas waste heat recovery, comprising: an intermittent industrial kiln 2; a high-temperature flue gas waste heat recovery unit 3, comprising a flue gas waste heat recovery pipeline 7, a fan 8 arranged on the flue gas waste heat recovery pipeline 7 and a first heat exchanger 9, the flue gas waste heat recovery pipeline 7 is in communication with the intermittent industrial kiln 2, the fan 8 is used for extracting high-temperature flue gas in the kiln 2, and the first heat exchanger 9 is used for recovering heat in the high-temperature flue gas; a flue gas waste heat utilization unit 4, comprising a flue gas waste heat utilization circuit 11, an internal heat exchange medium arranged in the flue gas waste heat utilization circuit 11, a driving machine 12, a second heat exchanger 13 and a user source 14, the driving machine 12 is used for driving the internal heat exchange medium to flow in the flue gas waste heat utilization circuit 11; a heat storage source 5, the heat storage source 5 is provided with a heat storage medium 15, the first heat exchanger 9 and the second heat exchanger 13 are both arranged in the heat storage medium 15, and are used for heat exchange through the heat storage medium 15.

[0032] It should be noted that the high-temperature flue gas generated in the intermittent industrial kiln 2 firing process flows into the first heat exchanger 9 under the suction action of the fan 8 through the flue gas waste heat recovery pipeline 7, and the high-temperature flue gas exchanges heat through the first heat exchanger 9 to store the flue gas waste heat in the heat storage medium 15 in the heat storage source 5 through convection heat exchange and heat conduction; The heat exchange medium enters the second heat exchanger 13 through the flue gas waste heat utilization circuit 11 under the suction action of the driving machine 12 and exchanges heat with the heat storage medium 15 through convection and heat conduction, and then the stored flue gas waste heat is replaced to supply the user source 14, thereby realizing the clean utilization of the high-temperature flue gas waste heat containing impurities. The internal heat exchange medium can be gas or fluid, if it is gas, the driving machine 12 can select the fan 8, if it is fluid, the driving machine 12 can select the fluid pump. The heat exchange medium can be combustion-supporting air, ceramic body drying hot air and steam required for the intermittent industrial kiln 2 combustion, and can also be industrial hot water, etc., so that the heat exchange medium can be directly utilized after heat exchange, which is more convenient and fast.

[0033] Specifically, the molten salt heat storage and heat supply system 1 for intermittent high-temperature flue gas waste heat recovery provided by the present application further comprises an intelligent control unit 6, which is electrically connected with the fan 8 and the driving machine 12, and is used for controlling the operating power of the fan 8 and the driving machine according to the working condition. The molten salt heat storage and heat supply system 1 for intermittent high-temperature flue gas waste heat recovery provided by the present application adopts the high-temperature flue gas waste heat recovery unit 3 to recover the heat of the flue gas, the heat storage source 5 to store the waste heat, and the flue gas waste heat utilization unit 4 to utilize the heat, thereby avoiding the problem that the high-temperature flue gas waste heat generated in the ceramic firing process cannot be directly utilized in the wrong time and space production link due to the intermittent production mode and the high impurity content. In addition, by setting the intelligent control unit 6, the power of the fan 8 and the driving machine 12 is adjusted according to the working condition to adjust the working medium flow, so that the heat supply demand of the user source 14 can be additionally guaranteed in the process of guaranteeing normal production.

[0034] Further, the intelligent control unit 6 comprises a fluid working condition testing component 17 and a controller 18, the controller 18 being electrically connected with the fluid working condition testing component 17, the fan 8 and the driving machine 12; the fluid working condition testing component 17 comprises a first temperature transmitter 19 arranged at the kiln 2, a second temperature transmitter 20 arranged at the flue gas waste heat utilization circuit 11, a first flow meter 21 arranged at the flue gas waste heat recovery pipeline 7 and a second flow meter 22 arranged at the flue gas waste heat utilization circuit 11. The first temperature transmitter 19 and the first flow meter 21 respectively feed back the internal temperature signal of the kiln 2 and the exhaust gas volume signal to the controller 18, the controller 18 automatically controls the frequency of the fan 8 to realize the exhaust gas energy storage under the normal firing condition of the ceramic products in the kiln 2 according to the preset function relationship between the temperature and the exhaust gas flow and after logical analysis and judgment; the controller 18 automatically calculates the heat supply Q1 according to the feedback signals of the second flow meter 22 and the second temperature transmitter 20 of the flue gas waste heat utilization circuit 11, and intelligently controls the frequency of the driving machine 12 according to the demand of the user source 14 to meet the preset heat supply demand Q0 of the user source 14. Specifically, when Q1>Q0+ε, the controller 18 reduces the fluid flow of the driving machine 12 by changing the frequency; when Q1<Q0+ε, the intelligent control center increases the fluid flow of the driving machine 12 by changing the frequency. Wherein, ε is the allowable fluid flow error.

[0035] Specifically, the heat storage source 5 comprises a heat storage tank 16, the heat storage tank 16 is internally provided with a containing cavity, the heat storage medium 15 is arranged in the containing cavity, and the heat storage tank 16 is externally provided with a heat preservation layer for preventing heat loss. The heat storage medium 15 can be selected as a substance with large specific heat capacity, and preferably a substance capable of phase change in the temperature range of the flue gas, so that the heat storage in the largest range can be realized. In the technical scheme provided in the present application, the heat storage medium 15 comprises heat storage molten salt, and the heat storage source 5 stores the heat replaced by the first heat exchanger 9 by means of the explicit heat storage and phase change heat storage of the heat storage molten salt.

[0036] It should be noted that the second temperature transmitter 20 and the second flow meter 22 in the flue gas waste heat utilization loop are located downstream of the second heat exchanger 13. The melting point of the heat storage molten salt is lower than the temperature of the high-temperature flue gas, and the upper limit temperature of the heat storage molten salt is higher than the temperature of the high-temperature flue gas. In the initial stage of heat exchange, the temperature of the heat storage molten salt continuously rises as heat exchange progresses; when the temperature reaches the melting point of the heat storage molten salt, the heat storage molten salt begins to undergo a phase change until all the heat storage molten salt in the heat storage tank 16 melts into liquid; in the final stage of heat exchange, the temperature of the heat storage molten salt continues to rise as heat exchange progresses. The heat storage source 5 uses two heat storage methods, namely heat storage molten salt storage and phase change heat storage, to store the high-temperature flue gas waste heat generated during the firing process of the kiln 2 within the corresponding molten salt heat storage operating temperature range, and provides a heat source during the heating period of the user source 14, thereby realizing the staggered utilization of high-temperature flue gas waste heat. It should be noted that the heat storage molten salt includes multiple salt components. The working temperature of the heat storage molten salt is determined by the ratio of each salt component. The salt component ratio can be adjusted according to the different melting points and upper working limits of different salt components, so that the melting point of the heat storage molten salt is lower than the temperature of the high-temperature flue gas, and the upper working limit temperature is higher than the temperature of the high-temperature flue gas.

[0037] Furthermore, to ensure the safety of the heat storage source 5 and prevent the heat storage molten salt from overheating and decomposing due to excessively high heat storage temperature, the intelligent control unit 6 also includes a third temperature transmitter 23. The third temperature transmitter 23 is installed inside the heat storage tank 16 and is used to monitor the working temperature of the heat storage molten salt. The third temperature transmitter 23 is electrically connected to the controller 18 and can reduce or shut down the fan 8 or increase the operating power of the drive motor 12 when the temperature of the heat storage molten salt exceeds the preset range, so as to reduce the temperature of the heat storage molten salt and prevent its decomposition.

[0038] Please see Figure 2 , Figure 2 The heat storage performance diagram of the molten salt thermal storage system is given. It can be seen from the diagram that the heat storage capacity per unit mass of molten salt increases rapidly with the heat exchange. After 5 hours of heat storage experiments, the heat storage capacity per unit mass of molten salt exceeded 600 kJ, showing a significant heat storage effect.

[0039] Furthermore, the high-temperature flue gas waste heat recovery unit 3 also includes a flue gas purifier 10, which is located at the outlet end of the flue gas waste heat recovery pipeline 7. The low-temperature flue gas, after being cooled by the first heat exchanger 9, flows into the flue gas purifier 10 for desulfurization and denitrification purification treatment, and then is discharged into the atmosphere to prevent the flue gas from polluting the atmosphere, making it more energy-efficient and environmentally friendly.

[0040] The molten salt heat storage and heat supply system 1 for intermittent high-temperature flue gas waste heat recovery provided by the application introduces a heat storage source 5 and an intelligent control unit 6 in the process of recycling high-temperature flue gas generated in the intermittent ceramic industrial kiln firing process, fully utilizes the high heat storage density and clean heat storage characteristics of the heat storage molten salt, realizes the recycling, storage and multi-dimensional, staggered space reuse of the intermittent industrial kiln flue gas waste heat, and solves the problem of low waste heat utilization rate of the high-temperature flue gas generated in the existing intermittent ceramic industrial kiln production process due to the intermittent production mode, unbalanced energy quality and high impurity content of the flue gas.

[0041] Finally, it should be noted that: the above examples are only used to illustrate the technical solutions of the present application, and not to limit them; although the present application has been described in detail with reference to the foregoing examples, those skilled in the art should understand that: it can still modify the technical solutions recorded in the foregoing examples, or make equivalent replacement for part of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solution deviate from the spirit and scope of the technical solutions of the embodiments of the present application.

Claims

1. A molten salt thermal storage heating system for intermittent high-temperature flue gas waste heat recovery, characterized in that, Comprising: An intermittent industrial kiln; A high-temperature flue gas waste heat recovery unit, including a flue gas waste heat recovery pipeline, a fan and a first heat exchanger provided on the flue gas waste heat recovery pipeline. The flue gas waste heat recovery pipeline is connected to the intermittent industrial kiln. The fan is used to extract high-temperature flue gas from the intermittent industrial kiln, and the first heat exchanger is used to recover the heat in the high-temperature flue gas; A flue gas waste heat utilization unit, including a flue gas waste heat utilization loop, a drive machine, a second heat exchanger, a user source and an internal heat exchange medium provided on the flue gas waste heat utilization loop. The drive machine is used to drive the internal heat exchange medium to flow in the flue gas waste heat utilization loop; A heat storage source, in which a heat storage medium is provided. Both the first heat exchanger and the second heat exchanger 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 and the drive machine, for controlling the operating power of the fan and the drive machine according to the working conditions. The intelligent control unit includes a fluid working condition testing component and a controller. The controller is electrically connected to the fluid working condition testing component, the fan and the drive machine; The fluid working condition testing component includes a first temperature transmitter provided on the intermittent industrial kiln, a second temperature transmitter provided on the flue gas waste heat utilization loop, a first flowmeter provided on the flue gas waste heat recovery pipeline, and a second flowmeter provided on the flue gas waste heat utilization loop. The controller is used to control the operating power of the fan according to the data of the first temperature transmitter and the first flowmeter, and is used to control the operating power of the drive machine according to the data of the second temperature transmitter, the second flowmeter and the heating demand of the user source; Wherein, the controller automatically regulates the frequency of the fan according to the preset function relationship between temperature and exhaust gas flow rate, and realizes exhaust gas energy storage under the normal firing conditions of ceramic products in the intermittent industrial kiln after logical analysis and judgment. The controller automatically calculates the heat supply Q1 according to the feedback signals of the second flowmeter and the second temperature transmitter on the flue gas waste heat utilization loop, and intelligently regulates the frequency of the drive machine according to the user source demand to meet the preset heating demand Q0 of the user source. When Q1>Q0+ε, the controller reduces the fluid flow rate of the drive machine by changing the frequency. When Q1<Q0+ε, the controller increases the fluid flow rate of the drive machine by changing the frequency; ε is the allowable fluid flow error; The second temperature transmitter and the second flowmeter are provided downstream of the second heat exchanger. The intelligent control unit further includes a third temperature transmitter provided in the heat storage tank, and the third temperature transmitter is electrically connected to the controller; The heat storage source includes a heat storage tank, which has a receiving cavity inside. The heat storage medium is disposed inside the receiving cavity, and the heat storage tank is provided with an insulation layer outside. The heat storage medium includes heat storage molten salt. The heat storage source stores the heat dissipated by the first heat exchanger by means of explicit heat storage and phase change heat storage of the heat storage molten salt. The melting point of the heat storage molten salt is lower than the temperature of the high-temperature flue gas, and the upper limit temperature of the heat storage molten salt is higher than the temperature of the high-temperature flue gas. The heat storage molten salt comprises multiple salt components, and the operating temperature of the heat storage molten salt is determined by the ratio of each salt component. The high-temperature flue gas waste heat recovery unit also includes a flue gas purifier, which is located at the outlet end of the flue gas waste heat recovery pipeline.

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