Flue gas waste heat utilization system

Abstract

The invention relates to a flue gas waste heat utilization system which comprises a plurality of heat storage devices which are sequentially communicated from upstream to downstream; the boiler communicates with the downstream of the most downstream one of the heat storage devices, the multiple kinds of flue gas communicate with the corresponding heat storage devices correspondingly, and the temperature of the flue gas communicating with any one of the heat storage devices is higher than that of the flue gas communicating with the upstream heat storage device. In the electricity utilization trough period, various kinds of flue gas are controlled to flow into the corresponding heat storage devices correspondingly and flow in the upstream direction, and heat release and heat storage are conducted step by step; and in the peak period of electricity utilization, various kinds of flue gas are controlled to flow into the corresponding heat storage devices respectively and flow towards the downstream, so that heat is absorbed from the heat storage devices till the flue gas flows into the boiler. The complexity of a flue gas waste heat utilization system is effectively simplified, and utilization equipment does not need to be arranged for flue gas at different temperatures. And the flue gas waste heat at each temperature can be fully utilized by the process of step-by-step heat release and step-by-step heat absorption, so that the utilization efficiency of the waste heat is improved.

Description

Technical Field

[0001] This disclosure relates to the field of flue gas waste heat utilization technology, specifically, to a flue gas waste heat utilization system. Background Technology

[0002] Industrial production generates a large amount of waste heat. Currently, the utilization level of industrial waste heat in China is relatively low, especially for low-quality waste heat, which needs further improvement. A typical waste heat utilization method is to use waste heat boilers for power generation. However, due to the inconsistent quality (variable temperature) of waste heat generated during industrial production, existing waste heat utilization systems require a wide variety of equipment. This means that different equipment needs to be set up for different qualities of flue gas, and the utilization efficiency for low-temperature, low-quality waste heat is relatively low. Summary of the Invention

[0003] The purpose of this disclosure is to provide a flue gas waste heat recovery system to at least partially solve the problems existing in the related technologies.

[0004] To achieve the above objectives, this disclosure provides a flue gas waste heat utilization system, wherein the flue gas includes multiple gases with different temperatures, and the flue gas waste heat utilization system includes: Multiple thermal storage devices, which are connected sequentially from upstream to downstream; and The boiler is connected downstream of the most downstream of the plurality of thermal storage devices. In this embodiment, various types of flue gas are respectively connected to a corresponding heat storage device, and the temperature of the flue gas connected to any one of the multiple heat storage devices is higher than the temperature of the flue gas connected to the heat storage device located upstream of it.

[0005] Optionally, each of the flue gases is also connected to one of the downstream heat storage devices or the boilers associated with its corresponding heat storage device.

[0006] Optionally, two of the plurality of said thermal storage devices and the boiler that are connected to the same type of flue gas are adjacent to each other.

[0007] Optionally, it also includes multiple electric heating devices, each used to heat its corresponding heat storage device.

[0008] Optionally, the plurality of thermal storage devices include a first thermal storage device, a second thermal storage device, and a third thermal storage device connected sequentially from upstream to downstream, and the plurality of flue gases include a first flue gas, a second flue gas, and a third flue gas with sequentially increasing temperatures. The first flue gas is connected to the first heat storage device and the second heat storage device, the second flue gas is connected to the second heat storage device and the third heat storage device, and the third flue gas is connected to the third heat storage device and the boiler.

[0009] Optionally, it also includes a fan connected downstream of the boiler.

[0010] Optionally, the fan is also connected to the upstream of the plurality of thermal storage devices.

[0011] Optionally, it also includes a chimney, with the most upstream of the plurality of thermal storage devices and the boiler respectively connected to the chimney.

[0012] Optionally, it also includes a purification device disposed at the air inlet of the chimney.

[0013] Optionally, the heat storage device is made of carbon-based material.

[0014] Through the above technical solution, during off-peak electricity demand, various flue gases can be controlled to flow into their respective heat storage devices and release heat. They then continue flowing upstream, releasing heat at each heat storage device until they reach the upstreammost device and are discharged. This achieves staged heat release and storage, with the heat storage temperature of multiple devices increasing sequentially from upstream to downstream. During peak electricity demand, various flue gases are controlled to flow into their respective heat storage devices and continue flowing downstream, absorbing heat from the higher-temperature storage devices until they flow into the boiler and release heat to generate steam. This design allows for staged deep heat release and storage of various flue gases during off-peak electricity demand and staged heat absorption and application to the same boiler during peak electricity demand. This effectively simplifies the complexity of the flue gas waste heat utilization system, eliminating the need for separate utilization equipment for flue gases at different temperatures and significantly reducing system operating costs. Furthermore, this process of stepwise heat release and stepwise heat absorption can make full use of the waste heat of flue gas at various temperatures. Low-quality flue gas at lower temperatures can also be gradually heated and fully utilized, thereby improving the utilization efficiency of waste heat of flue gas.

[0015] Other features and advantages of this disclosure will be described in detail in the following detailed description section. Attached Figure Description

[0016] The accompanying drawings are provided to further illustrate the present disclosure and form part of the specification. They are used together with the following detailed description to explain the present disclosure, but do not constitute a limitation thereof. In the drawings: Figure 1 This is a schematic diagram of a flue gas waste heat utilization system exemplarily illustrated according to this disclosure.

[0017] Explanation of reference numerals in the attached figures 101-First flue gas; 102-Second flue gas; 103-Third flue gas; 201-First thermal storage device; 202-Second thermal storage device; 203-Third thermal storage device; 3-Boiler; 4-Electric heating device; 5-Fan; 6-Chimney; 7-Purification device; 8-Generator set. Detailed Implementation

[0018] The specific embodiments of this disclosure will be described in detail below with reference to the accompanying drawings. It should be understood that the specific embodiments described herein are for illustration and explanation only and are not intended to limit this disclosure.

[0019] In this disclosure, unless otherwise stated, the terms "upstream" and "downstream" are used in relation to the flow direction of flue gas during peak power periods, i.e., during peak power periods, flue gas flows from upstream to downstream, and during off-peak power periods, flue gas flows from downstream to upstream.

[0020] In addition, the terms "first," "second," etc., used in this disclosure are for distinguishing one element from another and do not have sequential or importance. When the following description refers to the accompanying drawings, unless otherwise indicated, the same numbers in different drawings represent the same or similar elements.

[0021] Reference Figure 1 This disclosure exemplarily illustrates a flue gas waste heat utilization system. The flue gas includes multiple gases with different temperatures. The system comprises multiple heat storage devices connected sequentially from upstream to downstream, and a boiler 3 connected downstream of the most downstream of the multiple heat storage devices. The boiler is preferably a waste heat boiler, capable of generating steam using the waste heat of the flue gas. Each of the multiple flue gases is connected to a corresponding heat storage device, and the temperature of the flue gas connected to any one of the heat storage devices is higher than the temperature of the flue gas connected to the heat storage device upstream of it. That is, along the direction from upstream to downstream, the temperature of the flue gas connected to the multiple heat storage devices increases sequentially, so that after absorbing heat from the flue gas, the heat stored in the multiple heat storage devices also increases sequentially from upstream to downstream.

[0022] The flue gas can be of three, four, or other types, and can be adaptively designed according to the types of flue gas actually generated in industrial production. The flue gas is classified according to different temperatures and can be connected to the corresponding heat storage devices through pipelines. Correspondingly, a number of heat storage devices can be arranged according to the type of flue gas, and each heat storage device is connected to the corresponding type of flue gas through pipelines.

[0023] It should be noted that all the "connections" mentioned above in this disclosure can be achieved through pipelines, and various valves (not shown in the figure) can be installed at corresponding locations on the pipelines to control the flow direction and flow rate of flue gas in the system. Since the arrangement and use of valves are well known to those skilled in the art, they will not be described in detail here. As long as the flow direction of flue gas can be switched between upstream to downstream and downstream to upstream by controlling the valves, operation is convenient and system adjustment is flexible.

[0024] This disclosure does not limit the specific structure of the thermal storage device, which can be a solid thermal storage device that can store heat and release it when needed. Its specific composition will be described below.

[0025] By using the above technical solution, during off-peak electricity periods, various flue gases are controlled to flow into their respective heat storage devices and release heat. They then continue flowing upstream, passing through each upstream heat storage device in sequence until reaching the upstreammost device before exiting. This process achieves step-by-step heat release and storage within each heat storage device. Since the flue gas temperature is higher in downstream devices, the heat storage temperature of multiple devices increases sequentially from upstream to downstream. During peak electricity periods, various flue gases are controlled to flow into their respective heat storage devices and continue flowing downstream, absorbing heat from the higher-temperature devices until they flow into the boiler to release heat and generate steam. This design allows for step-by-step deep heat release and storage of various flue gases during off-peak periods and step-by-step heat absorption and application to the same boiler during peak periods. This effectively simplifies the complexity of the flue gas waste heat utilization system, eliminating the need for separate utilization equipment for flue gases at different temperatures and significantly reducing system operating costs. Furthermore, this process of stepwise heat release and stepwise heat absorption can make full use of the waste heat of flue gas at various temperatures, so that low-quality flue gas at lower temperatures can also be gradually heated and fully utilized, thereby improving the utilization efficiency of waste heat of flue gas.

[0026] Reference Figure 1 In the embodiments of this disclosure, each type of flue gas is also connected to one of the downstream heat storage devices or boilers 3 corresponding to its respective heat storage device. This design allows each type of flue gas to flow directly to the downstream heat storage device or boiler 3 during peak electricity periods by controlling the valves, preventing the flue gas from flowing through its corresponding heat storage device, thus avoiding the flue gas releasing heat towards that device and extending the flue gas circulation path and time, which would affect waste heat utilization efficiency.

[0027] Furthermore, referring to Figure 1In the embodiments of this disclosure, multiple heat storage devices and boiler 3 are arranged adjacent to each other when they are connected to the same type of flue gas. This design ensures that during peak power periods, each type of flue gas can absorb heat from the first heat storage device downstream of its corresponding heat storage device, continuing until it has absorbed heat from the last downstream heat storage device before being discharged to boiler 3. This arrangement allows the flue gas to absorb heat gradually at each stage, maximizing waste heat utilization. It should be noted that in this configuration, the flue gas with the highest temperature can flow directly to boiler 3.

[0028] In addition to the aforementioned implementation, in other embodiments, multiple heat storage devices and boiler 3 connected to the same flue gas may be spaced apart by other heat storage devices, which can be adapted to the actual waste heat utilization situation.

[0029] Reference Figure 1 In the embodiments of this disclosure, the flue gas waste heat utilization system may further include multiple electric heating devices 4, each used to heat its corresponding heat storage device. This design allows for lower electricity prices during off-peak hours, resulting in lower electricity costs. Therefore, multiple electric heating devices 4 can be controlled to heat their respective heat storage devices during off-peak hours, releasing heat from the heat storage devices to power the boiler during peak hours. Furthermore, the electric heating devices 4 effectively increase the heat storage temperature of the heat storage devices, thereby increasing their heat release capacity towards the flue gas and raising the flue gas temperature, further improving the waste heat quality of the flue gas. By utilizing the cyclical characteristics of off-peak and peak electricity and leveraging the price advantage of off-peak electricity, the use of peak electricity is reduced, further improving economic efficiency and reducing carbon emissions. In addition to utilizing off-peak electricity, unstable power sources such as wind power and solar power can also be used to power the electric heating devices 4, thus also incorporating renewable energy generation.

[0030] As stated above, this disclosure does not limit the number of thermal storage devices or the types and quantities of flue gas, for example in Figure 1 In the illustrated embodiment, the multiple thermal storage devices may include a first thermal storage device 201, a second thermal storage device 202, and a third thermal storage device 203 connected sequentially from upstream to downstream. The multiple flue gases may include a first flue gas 101, a second flue gas 102, and a third flue gas 103 with sequentially increasing temperatures. The first flue gas 101 may be connected to the first thermal storage device 201 and the second thermal storage device 202; the second flue gas 102 may be connected to the second thermal storage device 202 and the third thermal storage device 203; and the third flue gas 103 may be connected to the third thermal storage device 203 and the boiler 3. Furthermore, in some other embodiments, a fourth thermal storage device and a fourth flue gas, etc., may be interconnected. Figure 1 The embodiments shown are merely illustrative of the inventive concept of this disclosure and are not actually limited thereto.

[0031] Reference Figure 1 In embodiments of this disclosure, the flue gas waste heat utilization system may further include a fan 5 connected downstream of the boiler 3. By designing the fan 5, during peak power periods, the fan 5 is activated, and the valves are controlled to open and close, allowing various types of flue gas to flow downstream to the boiler 3, thereby improving waste heat utilization efficiency and flue gas flow velocity, increasing power generation efficiency, and enabling the establishment of internal flue gas circulation even when no waste heat flue gas flows in. In addition to the fan 5, in some other embodiments, fans may be added to various pipelines to increase the flue gas flow velocity; this disclosure does not limit this. It should be noted that even without the fan 5, the flue gas itself has pressure, allowing it to still flow within the system.

[0032] Furthermore, referring to Figure 1 In the embodiments disclosed herein, the fan 5 may also be connected to the upstream of a plurality of heat storage devices. With this design, during peak power periods, the high-temperature flue gas that has exchanged heat with the boiler 3 can be returned to the upstream heat storage device via the fan, where it can absorb heat and be progressively heated through multiple heat storage devices before finally reaching the boiler 3. This design fully utilizes the residual heat after heat exchange with the boiler 3, as well as the heat from the upstream heat storage device, and increases the flue gas circulation flow, thereby improving waste heat utilization efficiency and the power generation efficiency of the boiler 3.

[0033] Correspondingly, in Figure 1 In the embodiment shown, the flue gas waste heat recovery system may further include a generator set 8 for connection to the boiler 3. Steam generated by the boiler 3 drives the turbine of the generator set 8 to generate electricity. Furthermore, in some other embodiments, the heat generated by the boiler 3 may also be used for urban heating, etc.

[0034] Reference Figure 1 In embodiments of this disclosure, the flue gas waste heat utilization system may further include a chimney 6, with the upstreammost of a plurality of heat storage devices and the boiler 3 respectively connected to the chimney 6. With this design, during off-peak electricity periods, various types of flue gas flow upstream to the upstream heat storage device to release heat before being discharged through the chimney 6. When the peak electricity period ends and needs to transition to off-peak electricity, the flue gas that has exchanged heat with the boiler no longer participates in the circulation and can be discharged through the chimney 6.

[0035] To avoid environmental pollution and chimney blockage, refer to Figure 1In embodiments of this disclosure, the flue gas waste heat recovery system may further include a purification device 7 disposed at the air inlet of the chimney 6. This disclosure does not limit the specific structure of the purification device 7, for example, it may be a filter structure to recover particulate pollutants, nitrogen oxides, sulfides, VOCs, etc. in the flue gas.

[0036] In the embodiments of this disclosure, the thermal storage device can be made of carbon-based materials. Compared with the thermal storage materials such as magnesium bricks, phase change materials, and composite phase change materials used in traditional solid thermal storage devices, the high thermal density and high thermal conductivity of carbon-based materials can stably produce industrial steam. Compared with phase change materials such as molten salts, the system complexity and construction cost of carbon-based materials can be significantly reduced, and they have a wide temperature range, allowing for the storage of heat over a larger temperature range.

[0037] The preferred embodiments of this disclosure have been described in detail above with reference to the accompanying drawings. However, this disclosure is not limited to the specific details of the above embodiments. Within the scope of the technical concept of this disclosure, various simple modifications can be made to the technical solutions of this disclosure, and these simple modifications all fall within the protection scope of this disclosure.

[0038] It should also be noted that the various specific technical features described in the above specific embodiments can be combined in any suitable manner without contradiction. In order to avoid unnecessary repetition, this disclosure will not describe the various possible combinations separately.

[0039] Furthermore, various different embodiments of this disclosure can be combined in any way, as long as they do not violate the spirit of this disclosure, they should also be regarded as the content disclosed in this disclosure.

Claims

1. A flue gas waste heat recovery system, wherein the flue gas comprises multiple gases with different temperatures, characterized in that, The flue gas waste heat recovery system includes: Multiple thermal storage devices, which are connected sequentially from upstream to downstream; and The boiler is connected downstream of the most downstream of the plurality of thermal storage devices. In this embodiment, various types of flue gas are respectively connected to a corresponding heat storage device, and the temperature of the flue gas connected to any one of the multiple heat storage devices is higher than the temperature of the flue gas connected to the heat storage device located upstream of it.

2. The flue gas waste heat utilization system according to claim 1, characterized in that, Each of the flue gases is also connected to one of the downstream heat storage devices or the boilers associated with its corresponding heat storage device.

3. The flue gas waste heat utilization system according to claim 2, characterized in that, The multiple heat storage devices and the boilers that are connected to the same type of flue gas are adjacent to each other.

4. The flue gas waste heat utilization system according to any one of claims 1-3, characterized in that, It also includes multiple electric heating devices, each used to heat its corresponding heat storage device.

5. The flue gas waste heat utilization system according to any one of claims 1-3, characterized in that, The plurality of thermal storage devices include a first thermal storage device, a second thermal storage device, and a third thermal storage device connected sequentially from upstream to downstream. The plurality of flue gases include a first flue gas, a second flue gas, and a third flue gas with sequentially increasing temperatures. The first flue gas is connected to the first heat storage device and the second heat storage device, the second flue gas is connected to the second heat storage device and the third heat storage device, and the third flue gas is connected to the third heat storage device and the boiler.

6. The flue gas waste heat utilization system according to claim 1, characterized in that, It also includes a fan connected downstream of the boiler.

7. The flue gas waste heat utilization system according to claim 6, characterized in that, The fan is also connected to the upstream one of the plurality of thermal storage devices.

8. The flue gas waste heat utilization system according to claim 1, characterized in that, It also includes a chimney, with the most upstream of the plurality of thermal storage devices and the boiler respectively connected to the chimney.

9. The flue gas waste heat utilization system according to claim 8, characterized in that, It also includes a purification device installed at the air inlet of the chimney.

10. The flue gas waste heat utilization system according to claim 1, characterized in that, The thermal storage device is made of carbon-based materials.

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