CFB (circulating fluid bed) boiler for heating fused salt by extracting smoke from tail flue

Abstract

The invention provides a CFB (circulating fluid bed) boiler for heating molten salt by sucking smoke in a tail flue, and belongs to the technical field of CFB boilers coupled with molten salt heat storage. The problem that the scale and efficiency improvement of industrial production are seriously limited due to the fact that a traditional CFB boiler unit is generally lack of high-capacity and high-parameter industrial gas supply capacity is solved. The system comprises a hearth, a separating and returning system and a tail flue, the separating and returning system comprises a cyclone separator, and a low-temperature superheater high-temperature section, a low-temperature superheater low-temperature section, a high-temperature economizer, an SCR device, a low-temperature economizer and an air preheater are sequentially arranged in the tail flue in the flowing direction. A high-temperature flue gas leading-out pipeline is arranged between the low-temperature superheater high-temperature section and the low-temperature superheater low-temperature section, a low-temperature flue gas leading-out pipeline is arranged between the high-temperature economizer and the SCR device, and the outlet end of the high-temperature flue gas leading-out pipeline and the outlet end of the low-temperature flue gas leading-out pipeline are both connected with the inlet end of the mixer. The device is mainly used for the CFB boiler unit.

Description

Technical Field

[0001] The invention belongs to the technical field of molten salt heat storage coupled CFB boilers, and in particular relates to a CFB boiler that heats molten salt with flue gas extracted from a tail flue. Background Art

[0002] In the current energy field, traditional systems are facing many problems that need to be solved urgently. In terms of industrial gas supply, traditional CFB boiler units generally lack the ability to supply large-capacity and high-parameter industrial gas. This defect makes it unable to fully meet the increasingly stringent requirements of modern industrial production for steam parameters and supply, which seriously limits the scale and efficiency of industrial production.

[0003] The restriction on industrial gas supply has further produced a chain reaction, which has a negative impact on the peak load and frequency regulation capabilities of the units. In the power system, peak load and frequency regulation capabilities are crucial to maintaining the stable operation of the power grid. Due to the shortcomings of traditional CFB boiler units in this regard, when the power load fluctuates, the units are difficult to respond quickly and effectively, and cannot adjust the power generation in time to match the changes in power demand, which brings hidden dangers to the stable power supply of the power grid and increases the risks and costs of power grid operation.

[0004] At the same time, the importance of energy storage technology in the modern energy system is increasing day by day. As a highly promising energy storage technology, molten salt energy storage has gradually entered people's field of vision. It uses molten salt as an energy storage medium and has a series of outstanding advantages. Its strong peak-shaving capacity enables it to store energy during the low-load period and release energy during the peak period, effectively balancing the supply and demand of electricity; its suitability for large-scale applications makes it possible for its widespread promotion in the energy field; its long service life means lower long-term cost investment; its excellent economic benefits are reflected in its ability to create more economic value while optimizing energy utilization; and the technology is safe and environmentally friendly, in line with the current concept of sustainable development and strict environmental protection requirements.

[0005] However, the molten salt energy storage technology and CFB units have not yet achieved full and effective coupling integration and flexible use. How to organically combine the advantages of molten salt energy storage with CFB boiler units, overcome the above-mentioned problems of traditional CFB boiler units, and build a more efficient, stable and green energy system has become a key problem that needs to be overcome in the energy field. Summary of the invention

[0006] In view of this, the present invention aims to propose a CFB boiler that uses flue gas from the tail flue to heat molten salt, so as to solve the problem that traditional CFB boiler units generally lack large-capacity and high-parameter industrial gas supply capacity, thereby seriously limiting the scale and efficiency improvement of industrial production.

[0007] To achieve the above-mentioned purpose, the present invention adopts the following technical scheme: a CFB boiler for heating molten salt by exhausting flue gas from a tail flue, which comprises a furnace, a separation and return system and a tail flue, wherein the separation and return system comprises a cyclone separator, wherein the inlet end of the cyclone separator is connected to the exhaust port of the furnace, the solid outlet of the cyclone separator is connected to the furnace through a pipeline, the gas outlet of the cyclone separator is connected to the inlet end of the tail flue, and the tail flue is provided with a high temperature section of a low temperature superheater, a low temperature section of a low temperature superheater, a high temperature economizer, an S CR device, low-temperature economizer and air preheater, a high-temperature flue gas outlet pipeline is arranged between the high-temperature section of the low-temperature superheater and the low-temperature section of the low-temperature superheater, a low-temperature flue gas outlet pipeline is arranged between the high-temperature economizer and the SCR device, the outlet ends of the high-temperature flue gas outlet pipeline and the low-temperature flue gas outlet pipeline are both connected to the inlet end of the mixer, the outlet end of the mixer is connected to the inlet end of the molten salt heat exchanger, a heat exchange flue gas introduction pipeline is arranged between the high-temperature economizer and the SCR device, and the outlet end of the molten salt heat exchanger is connected to the heat exchange flue gas introduction pipeline.

[0008] Furthermore, a screen-type heating surface is provided in the furnace.

[0009] Furthermore, a wind chamber is provided at the bottom of the furnace.

[0010] Furthermore, the CFB boiler that heats molten salt with flue gas extracted from the tail flue also includes a fan system, which includes a primary fan, a secondary fan, a primary air duct and a secondary air duct. The primary fan is connected to the wind chamber through the primary air duct, and the secondary fan is connected to the furnace through the secondary duct.

[0011] Furthermore, the primary air duct and the secondary air duct both pass through the air preheater.

[0012] Furthermore, a high-pressure fan is connected to the pipeline between the solid outlet of the cyclone separator and the furnace.

[0013] Furthermore, an induced draft fan is provided on the heat exchange flue gas introduction pipeline.

[0014] Furthermore, both the high-temperature flue gas outlet pipeline and the low-temperature flue gas outlet pipeline are provided with adjustment baffles.

[0015] Furthermore, a return valve is provided at the solid outlet of the cyclone separator.

[0016] Furthermore, the furnace is provided with a feeding port.

[0017] Compared with the prior art, the present invention has the following beneficial effects:

[0018] 1. The present invention provides a CFB boiler that heats molten salt by extracting flue gas from a tail flue. The tail flue gas is led out to a bypass molten salt heat exchanger through the flue, and the molten salt working medium is heated by the flue gas. With the advantage of molten salt energy storage, the industrial gas supply capacity of the boiler can be effectively improved, and the higher requirements of industrial production on steam parameters and supply can be met, alleviating the limitations of traditional units in this regard.

[0019] 2. The present invention provides a CFB boiler that uses flue gas from the tail flue to heat molten salt, combines molten salt energy storage with CFB units, improves the peak-shaving capability of the units, and enhances the peak-shaving and frequency-regulating performance of the entire units. When the power load fluctuates, the energy stored or released by the molten salt can be used to quickly respond to grid demand, ensure the stability and reliability of power supply, and overcome the problem that the peak-shaving and frequency-regulating capabilities of traditional CFB boiler units are limited by industrial gas supply;

[0020] 3. The present invention provides a CFB boiler that heats molten salt by extracting flue gas from a tail flue, and is provided with a flue gas regulating means, which can ensure that the molten salt system can stably absorb heat according to different boiler load conditions. At the same time, by providing a high-temperature flue gas outlet pipeline and a low-temperature flue gas outlet pipeline in the tail flue, and using a mixer to achieve matching of flue gas temperature and flue gas volume, it is ensured that under various working conditions, the molten salt in the bypass molten salt heat exchanger can efficiently exchange heat with the flue gas of appropriate temperature and flow, thereby maintaining the stable operation of the molten salt system and improving the thermal efficiency of the entire system;

[0021] 4. The present invention provides a CFB boiler that heats molten salt by extracting flue gas from a tail flue. An induced draft fan is arranged at the flue outlet to provide stable flue gas power for the bypass flue, thereby ensuring the stability of the flue gas heat exchange system. The stable flue gas power enables the flue gas to flow continuously and stably in the system, which not only ensures the heat exchange effect between the flue gas and the molten salt, but also ensures the good performance of the heat exchange regulation characteristics of the system, making the operation of the entire CFB boiler and molten salt heat storage coupling system more reliable and efficient;

[0022] 5. The present invention provides a CFB boiler that uses flue gas from the tail flue to heat molten salt, constructs a new power system with new energy as the theme, applies molten salt heat storage to the CFB boiler, and promotes the realization of green and low-carbon development goals. This coupling method improves energy utilization efficiency and reduces energy waste and pollutant emissions. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] The accompanying drawings constituting a part of the present invention are used to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention. In the accompanying drawings:

[0024] Figure 1 This is a schematic diagram of the overall structure of a CFB boiler for heating molten salt with flue gas extracted from a tail flue according to the present invention.

[0025] 1-furnace, 2-screen heating surface, 3-cyclone separator, 4-tail flue, 5-high temperature section of low temperature superheater, 6-low temperature section of low temperature superheater, 7-high temperature economizer, 8-SCR device, 9-low temperature economizer, 10-air preheater, 11-mixer, 12-molten salt heat exchanger, 13-induced draft fan, 14-adjusting damper, 15-primary fan, 16-secondary fan, 17-high pressure fan, 18-wind chamber. DETAILED DESCRIPTION

[0026] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely explain the technical solutions in the embodiments of the present invention. It should be noted that the embodiments of the present invention and the features in the embodiments can be combined with each other without conflict, and the described embodiments are only part of the embodiments of the present invention, not all of the embodiments.

[0027] See also Figure 1 To illustrate the present embodiment, a CFB boiler for heating molten salt by exhausting flue gas from a tail flue comprises a furnace 1, a separation and recycling system and a tail flue 4, wherein the separation and recycling system comprises a cyclone separator 3, wherein the inlet end of the cyclone separator 3 is connected to the exhaust port of the furnace 1, the solid outlet of the cyclone separator 3 is connected to the furnace 1 through a pipeline, the gas outlet of the cyclone separator 3 is connected to the inlet end of the tail flue 4, and the tail flue 4 is provided with a low-temperature superheater high-temperature section 5, a low-temperature superheater low-temperature section 6, a high-temperature economizer 7, an SCR device 8, a low-temperature economizer 9 and an air preheater 10 in sequence along the flow direction, a high-temperature flue gas outlet pipeline is provided between the low-temperature superheater high-temperature section 5 and the low-temperature superheater low-temperature section 6, and the high-temperature superheater high-temperature section 6 is provided with a high-temperature superheater high-temperature section 5. A low-temperature flue gas outlet pipeline is arranged between the warm economizer 7 and the SCR device 8, and the outlet ends of the high-temperature flue gas outlet pipeline and the low-temperature flue gas outlet pipeline are both connected to the inlet end of the mixer 11, and the outlet end of the mixer 11 is connected to the inlet end of the molten salt heat exchanger 12. A heat exchange flue gas introduction pipeline is arranged between the high-temperature economizer 7 and the SCR device 8, and the outlet end of the molten salt heat exchanger 12 is connected to the heat exchange flue gas introduction pipeline. In this embodiment, the tail flue gas is led out to the bypass molten salt heat exchanger 12 through the tail flue 4, and the molten salt working medium is heated by the flue gas. With the advantage of molten salt energy storage, the industrial gas supply capacity of the boiler can be effectively improved, and the higher requirements of industrial production on steam parameters and supply volume can be met, alleviating the limitations of traditional units in this regard.

[0028] The cyclone separator 3 in this embodiment includes but is not limited to being in the form of insulation, water cooling, and steam cooling.

[0029] In this embodiment, molten salt energy storage is combined with the CFB unit to improve the peak-shaving capability of the unit, and enhance the peak-shaving and frequency-regulating performance of the entire unit. When the power load fluctuates, the energy stored or released by the molten salt can be used to quickly respond to grid demand, ensure the stability and reliability of power supply, and overcome the problem that the peak-shaving and frequency-regulating capabilities of traditional CFB boiler units are limited by industrial gas supply.

[0030] In the present embodiment, a platen-type heating surface 2 is arranged in the furnace 1. In the present embodiment, the platen-type heating surface 2 includes but is not limited to a water-cooled platen and a platen-type superheater.

[0031] In this embodiment, a wind chamber 18 is provided at the bottom of the furnace 1, and the CFB boiler that draws flue gas from the tail flue 4 to heat the molten salt also includes a fan system, which includes a primary fan 15, a secondary fan 16, a primary air duct and a secondary air duct. The primary fan 15 is connected to the wind chamber through a primary air duct, and the secondary fan 16 is connected to the furnace 1 through a secondary duct. The primary fan 15 and the secondary fan 16 provide primary air and secondary air to the wind chamber and the furnace 1 respectively. The primary air enters the wind chamber to blow up the materials accumulated at the bottom of the furnace 1 to facilitate the full combustion of the materials. The secondary air enters the furnace 1 to provide oxygen for the combustion of the materials.

[0032] In this embodiment, the primary air duct and the secondary air duct both pass through the air preheater 10, and the air preheater 10 is used to preheat the primary air and the secondary air in the primary air duct and the secondary air duct.

[0033] In this embodiment, a high-pressure fan 17 is connected to the pipeline between the solid outlet of the cyclone separator 3 and the furnace 1. The high-pressure fan 17 is used to blow the solid particles separated by the cyclone separator 3 into the furnace 1 to prevent the solid particles from accumulating in the pipeline and causing pipeline blockage.

[0034] In this embodiment, an induced draft fan 13 is arranged on the heat exchange flue gas inlet pipeline, and the induced draft fan 13 is arranged at the flue outlet to provide stable flue gas power for the bypass flue, thereby ensuring the stability of the flue gas heat exchange system. The stable flue gas power enables the flue gas to flow continuously and stably in the system, which not only ensures the heat exchange effect between the flue gas and the molten salt, but also ensures the good performance of the heat exchange regulation characteristics of the system, making the operation of the entire CFB boiler and molten salt heat storage coupling system more reliable and efficient.

[0035] In the present embodiment, both the high-temperature flue gas outlet pipeline and the low-temperature flue gas outlet pipeline are provided with an adjusting baffle 14. By adjusting the baffle 14, a flue gas regulating means is provided, and the molten salt system can be guaranteed to absorb heat stably according to different boiler load conditions. At the same time, by providing a high-temperature flue gas outlet pipeline and a low-temperature flue gas outlet pipeline in the tail flue, and using the mixer 11 to achieve matching of flue gas temperature and flue gas volume, it is ensured that under various working conditions, the molten salt in the bypass molten salt heat exchanger can efficiently exchange heat with the flue gas of appropriate temperature and flow, thereby maintaining stable operation of the molten salt system and improving the thermal efficiency of the entire system.

[0036] In this embodiment, a return valve is provided at the solid outlet of the cyclone separator 3 , and the return valve is used to control the on-off of the pipeline between the solid outlet of the cyclone separator 3 and the furnace 1 .

[0037] In this embodiment, the furnace 1 is provided with a feeding port, and the feeding port is used to feed coal and limestone into the furnace 1.

[0038] In this embodiment, a new power system with new energy as the theme is constructed, and molten salt heat storage is applied to CFB boilers, which promotes the realization of green and low-carbon development goals. This coupling method improves energy utilization efficiency and reduces energy waste and pollutant emissions.

[0039] The embodiments of the present invention disclosed above are only used to help illustrate the present invention. The embodiments do not describe all the details in detail, nor do they limit the invention to the specific implementation methods described. According to the content of this specification, many modifications and changes can be made. This specification selects and specifically describes these embodiments in order to better explain the principles and practical applications of the present invention, so that those skilled in the art can understand and use the present invention well.

Claims

1. A CFB boiler that heats molten salt with flue gas from the tail flue, characterized in that: It comprises a furnace (1), a separation and recycling system and a tail flue (4), wherein the separation and recycling system comprises a cyclone separator (3), wherein the inlet end of the cyclone separator (3) is connected to the smoke exhaust port of the furnace (1), the solid outlet of the cyclone separator (3) is connected to the furnace (1) through a pipeline, and the gas outlet of the cyclone separator (3) is connected to the inlet end of the tail flue (4), and the tail flue (4) is provided with a high temperature section (5) of a low temperature superheater, a low temperature section (6) of a low temperature superheater, a high temperature economizer (7), an SCR device (8), a low temperature economizer (9) and an air preheater (10) in sequence along the flow direction. 10), a high-temperature flue gas outlet pipeline is provided between the high-temperature section (5) of the low-temperature superheater and the low-temperature section (6) of the low-temperature superheater, a low-temperature flue gas outlet pipeline is provided between the high-temperature economizer (7) and the SCR device (8), the outlet ends of the high-temperature flue gas outlet pipeline and the low-temperature flue gas outlet pipeline are both connected to the inlet end of the mixer (11), the outlet end of the mixer (11) is connected to the inlet end of the molten salt heat exchanger (12), a heat exchange flue gas inlet pipeline is provided between the high-temperature economizer (7) and the SCR device (8), and the outlet end of the molten salt heat exchanger (12) is connected to the heat exchange flue gas inlet pipeline.

2. A CFB boiler for heating molten salt with flue gas from the tail flue according to claim 1, characterized in that: A screen-type heating surface (2) is arranged in the furnace (1).

3. A CFB boiler for heating molten salt with flue gas from the tail flue according to claim 1, characterized in that: A wind chamber (18) is provided at the bottom of the furnace (1).

4. A CFB boiler for heating molten salt with flue gas from the tail flue according to claim 1, characterized in that: The CFB boiler that uses flue gas from the tail flue (4) to heat molten salt also includes a fan system, which includes a primary fan (15), a secondary fan (16), a primary air duct and a secondary air duct. The primary fan (15) is connected to the wind chamber via the primary air duct, and the secondary fan (16) is connected to the furnace (1) via the secondary duct.

5. A CFB boiler for heating molten salt with flue gas from the tail flue according to claim 4, characterized in that: The primary air duct and the secondary air duct both pass through the air preheater (10).

6. A CFB boiler for heating molten salt with flue gas from the tail flue according to claim 1, characterized in that: A high-pressure fan (17) is connected to the pipeline between the solid outlet of the cyclone separator (3) and the furnace (1).

7. The CFB boiler for heating molten salt with flue gas from the tail flue according to claim 1, characterized in that: An induced draft fan (13) is arranged on the heat exchange flue gas introduction pipeline.

8. The CFB boiler for heating molten salt with flue gas from the tail flue according to claim 1, characterized in that: The high-temperature flue gas outlet pipeline and the low-temperature flue gas outlet pipeline are both provided with an adjustment baffle (14).

9. A CFB boiler for heating molten salt with flue gas from the tail flue according to claim 1, characterized in that: A return valve is provided at the solid outlet of the cyclone separator (3).

10. The CFB boiler for heating molten salt with flue gas from the tail flue according to claim 1, characterized in that: The furnace (1) is provided with a feeding port.

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