Dual-heat-source waste heat recovery and flue gas white smoke elimination system and working method

Abstract

The application discloses a double-heat-source waste heat recovery and flue gas white smoke elimination system and a working method, which can provide heat to users in the operation modes of double-heat-source single heating, parallel heating or cascade heating through the transportation of a pipeline system and the switching of valves according to the economy of the system, is favorable for maximizing the economy of the heating system, and solves the problems that the heating mode of the heating system in the prior art cannot be regulated according to the economy, the waste heat resources are not fully utilized, and the economy maximization cannot be realized. The application realizes three-stage utilization of flue gas waste heat through a flue gas waste heat utilization system, including heating gas by using flue gas waste heat to improve the combustion efficiency of a gas boiler burner, making flue gas waste heat enter an air source heat pump heating circulation system to improve the performance of the air source heat pump, and heating boiler air inlet by using flue gas waste heat to improve the efficiency of the boiler, so that the waste heat resources are fully utilized step by step and the smoke plume is eliminated, and visual pollution caused by flue gas emission is avoided.

Description

Technical Field

[0001] This invention relates to the technical field of boiler heating and waste heat recovery, and in particular to a dual-heat-source waste heat recovery and flue gas whitening system and its working method. Background Technology

[0002] Chinese patent CN209744518U discloses an electrically controlled mixed heat source centralized domestic hot water system, including a water volumetric heat exchanger. The water volumetric heat exchanger has a hot water chamber and a heat exchange chamber, which can exchange heat. The hot water chamber has a first inlet, a first outlet, a second inlet, and a second outlet. The first inlet and the first outlet are respectively connected to the outlet pipe and inlet pipe of an air source circulating hot water subsystem. The second inlet is connected to a return water device, and the second outlet is connected to a domestic water terminal. The return water device is equipped with a first thermometer, and the second outlet is equipped with a second thermometer. The third inlet of the heat exchange chamber is connected to the inlet pipe of a boiler circulating hot water subsystem, and the third outlet of the heat exchange chamber is connected to the outlet pipe of the boiler circulating hot water subsystem.

[0003] In the aforementioned document, when all air source heat pump water heaters are started, and the first thermometer detects that the water temperature is still below 50°C, the second electric valve is activated, the boiler circulation pump is started, and finally the gas boiler is turned on to provide 85°C-60°C high-temperature hot water into the heat exchange chamber of the water volumetric heat exchanger. The heat exchange chamber exchanges heat with the hot water chamber to heat the hot water in the hot water chamber and ensure the supply of hot water at low temperatures.

[0004] The aforementioned documents disclose both series-connected cascade heating of the air source heat pump water heater unit and the boiler circulating hot water subsystem, and individual heating of the air source heat pump water heater unit. This series-connected cascade heating method is only effective in winter or autumn when the outside temperature is low and the air source heat pump water heater unit cannot heat the water to the required temperature. In this case, the economic efficiency of this series-connected cascade heating method is relatively improved. However, in spring or summer when the outside temperature is high and the air source heat pump water heater unit can heat the water to the required temperature, the individual heating method of the air source heat pump water heater unit can be used to maximize the utilization of air heat, and the economic efficiency can also be relatively improved.

[0005] In actual heating systems, under partial load, the economical gas-to-electricity price ratio for heating needs to be calculated based on gas and electricity prices, as well as gas-to-heat and electricity-to-heat conversion efficiencies. Then, based on this ratio, the appropriate operating mode for the heating system is determined, and the system is adjusted to the most suitable mode. Under full load, the primary operating mode is determined based on the economical gas-to-electricity price ratio. In this case, the air-source heat pump water heater and the boiler circulating hot water system need to be connected in parallel for heating. Only after this calculation and determination can the heating system be adjusted to use the air-source heat pump water heater and the boiler circulating hot water system in parallel for heating, and the primary heating system (either the air-source heat pump water heater or the boiler circulating hot water system) be determined to maximize the overall economic efficiency of the heating system. However, the aforementioned electrically controlled mixed heat source centralized domestic hot water system cannot connect the air-source heat pump water heater and the boiler circulating hot water system in parallel for heating, and the heating mode cannot be adjusted based on economic efficiency. Furthermore, the aforementioned documents do not utilize the waste heat resources of transformers in air source heat pump water heaters and flue gas in boiler circulating hot water systems. This waste heat resources are wasted, reducing resource utilization and hindering the maximization of the economic efficiency of the heating system. Summary of the Invention

[0006] To address the shortcomings in the aforementioned background technology, this invention proposes a dual-heat-source waste heat recovery and flue gas whitening system and its operating method, which solves the problems in the existing heating system where the heating mode cannot be adjusted according to economic efficiency, waste heat resources are not fully utilized, and economic efficiency cannot be maximized.

[0007] The technical solution of this invention is implemented as follows: A dual-heat-source waste heat recovery and flue gas whitening elimination system includes a user heating system, on which a gas-fired boiler hot water circulation system and an air-source heat pump hot water circulation system are connected; the gas-fired boiler hot water circulation system or the air-source heat pump hot water circulation system supplies heat to the user heating system independently; or the gas-fired boiler hot water circulation system and the air-source heat pump hot water circulation system are connected in series to supply heat to the user heating system; or the hot water circulation system and the air-source heat pump hot water circulation system are connected in parallel to supply heat to the user heating system; the gas-fired boiler hot water circulation system is equipped with a gas preheating system and a gas-fired boiler burner air preheating system; the air-source heat pump hot water circulation system is equipped with a transformer cabinet waste heat utilization system, the air-source heat pump hot water circulation system is connected to a flue gas waste heat utilization system, the gas preheating system and the gas-fired boiler burner air preheating system are respectively connected to the flue gas waste heat utilization system, and the flue gas waste heat utilization system is connected to a boiler flue gas whitening elimination system.

[0008] Preferably, the user heating system includes a user-side hot water return main pipeline and a user-side hot water supply main pipeline that are interconnected. The user-side hot water supply main pipeline and the user-side hot water return main pipeline are respectively connected to the outlet and inlet of the condenser on the user side. The user-side hot water supply main pipeline is respectively connected to the outlet and inlet of the heat exchanger on the user side. The user-side hot water return main pipeline is connected to the inlet of the heat exchanger on the user side. A condenser outlet water pipeline valve B is provided on the hot water supply main pipeline located between the outlet and inlet of the heat exchanger on the user side. The outlet and inlet of the condenser on the user side are respectively connected to an air source heat pump hot water circulation system, and the outlet and inlet of the heat exchanger on the user side are respectively connected to a gas boiler hot water circulation system.

[0009] Preferably, the gas-fired boiler hot water circulation system includes a gas-fired boiler body, a gas-fired boiler burner on the gas-fired boiler body, and a gas pipeline connected to the gas-fired boiler burner; the inlet and outlet of the gas-fired boiler body are respectively connected to the outlet and inlet on the side of the heat exchanger furthest from the user.

[0010] Preferably, the gas preheating system includes a gas preheater, a gas pipeline, gas pipeline valves, and a flue gas pipeline. The gas preheater is connected in parallel to the gas pipeline. The gas preheater inlet pipeline valve and the gas preheater outlet pipeline valve are respectively installed at the inlet and outlet of the gas preheater. A gas pipeline valve is installed on the gas pipeline located between the inlet and outlet of the gas preheater. The gas preheater is connected to the gas boiler body through the flue gas pipeline.

[0011] Preferably, the air preheating system for the gas-fired boiler burner includes a solution dehumidifier B, an air heat exchanger, an air duct A, a first air preheating pipe, and a second air preheating pipe. The first inlet of the solution dehumidifier B is connected to the air duct A, which is in communication with the air. The first outlet of the solution dehumidifier B is connected to the air heat exchanger via the second air preheating pipe. The air heat exchanger is connected to the gas-fired boiler burner via the first air preheating pipe, and is in communication with the air via the air duct A.

[0012] Preferably, the flue gas waste heat utilization system includes a solution dehumidifier A, a solution dehumidifier B, a regenerator, a flue gas pipeline, a first dehumidifying liquid circulation pipeline, a second dehumidifying liquid circulation pipeline, and a third dehumidifying liquid circulation pipeline. The solution dehumidifier A is connected to the first inlet of the regenerator through the first dehumidifying liquid circulation pipeline, and a dehumidifying liquid circulation pump is provided on the first dehumidifying liquid circulation pipeline. The first outlet of the regenerator is connected to the solution dehumidifier B through the second dehumidifying liquid circulation pipeline. The solution dehumidifier B is connected to the air heat exchanger through a second air preheating pipeline.

[0013] Preferably, the boiler flue gas whitening system includes a flue gas air cooler, which is connected to the solution dehumidifier A through a whitening pipeline.

[0014] Preferably, the air source heat pump hot water circulation system includes a regenerator, a compressor, a condenser, a throttling valve, and an evaporator. The evaporator is connected to the second inlet of the regenerator, and the second outlet of the regenerator is connected to the compressor. The outlet and inlet of the condenser on the side away from the user are respectively connected to the compressor and the evaporator. The throttling valve is located between the condenser and the evaporator.

[0015] Preferably, the transformer cabinet waste heat utilization system includes a transformer cabinet, which is connected to an evaporator and connected to the air via an air duct C.

[0016] A method for operating a dual-heat-source waste heat recovery and flue gas whitening system, used in the aforementioned dual-heat-source waste heat recovery and flue gas whitening system.

[0017] The beneficial effects of this invention are:

[0018] 1. This invention employs a dual-energy complementary heating system combining a gas-fired boiler hot water circulation system and an air-source heat pump hot water circulation system. Through pipeline transportation and valve switching, it achieves four heating supply methods to users: the gas-fired boiler hot water circulation system provides heat to the user's heating system independently; the air-source heat pump hot water circulation system provides heat to the user's heating system independently; the gas-fired boiler hot water circulation system and the air-source heat pump hot water circulation system are connected in parallel to provide heat to the user's heating system; and the hot water generated by the air-source heat pump hot water circulation system is heated in stages by the gas-fired boiler hot water circulation system before being supplied to the user's heating system. The heating method can be adjusted according to economic considerations. Furthermore, this invention utilizes a flue gas waste heat utilization system to preheat the intake air and gas of both the gas-fired boiler hot water circulation system and the air-source heat pump hot water circulation system, and to treat the exhaust flue gas to eliminate white spots. This maximizes resource utilization, prevents waste heat resources from being wasted, and helps maximize the economic efficiency of the heating system. This solves the problems in existing technologies where the heating mode cannot be adjusted according to economic considerations, waste heat resources are not fully utilized, and economic maximization is not achieved.

[0019] 2. This invention employs a cooling and dehumidification method to further utilize the waste heat of flue gas and eliminate plume. Boiler flue gas is transported through a flue gas pipeline. In a solution dehumidifier A, the dehumidifying liquid is heated and humidified, changing from a concentrated solution to a dilute solution. The dilute dehumidifying liquid is then pumped to a regenerator via a dehumidifying liquid circulation pump. In the regenerator, some heat is transferred to the refrigerant before entering a solution dehumidifier B. In solution dehumidifier B, mass transfer and heat exchange occur with the outdoor cold air, cooling and regenerating the solution. The moisture in the solution transfers mass to the cold air for dehumidification, changing the dehumidifying solution from a dilute solution to a concentrated solution, which then enters solution dehumidifier A for the next cycle. This process of recycling the waste heat in the flue gas solves the technical problem in existing technologies where dehumidifying solution regeneration and plume elimination require additional energy consumption.

[0020] 3. This invention utilizes flue gas waste heat in three stages. In the first stage, the fuel temperature in the gas-fired boiler hot water circulation system is low in winter, affecting the energy efficiency of the boiler burner. A gas preheater is used to heat the gas using the flue gas waste heat, thus utilizing the heat and improving the combustion efficiency of the boiler burner. In the second stage, the heating performance of the air source heat pump hot water circulation system decreases in low temperature and high humidity conditions during winter, and in severe cases, it may shut down for defrosting. The diluted solution from the solution dehumidifier A is circulated into the regenerator, and the heat enters the air source heat pump hot water circulation system, thus utilizing the waste heat a second time and improving the performance of the system. In the third stage, the efficiency of the gas-fired boiler burner decreases as the inlet air temperature decreases. The heated air from the solution dehumidifier B enters the air heat exchanger and then into the gas-fired boiler burner, thus heating the inlet air and utilizing the waste heat a third time, improving the burner's efficiency. Attached Figure Description

[0021] To more clearly illustrate the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0022] Figure 1 This is a schematic diagram of the present invention.

[0023] In the diagram: 1. Gas boiler boiler body; 2. Gas boiler burner; 3. Gas preheater; 4. Solution dehumidifier A; 5. Solution dehumidifier B; 6. Gas boiler flue gas fan; 7. Dehumidifying liquid circulation pump; 8. Flue gas air cooler; 9. Air fan A; 10. Air heat exchanger; 11. Air fan B; 12. Regenerator; 13. Compressor; 14. Condenser; 15. Throttling valve; 16. Evaporator; 17. Hot water circulation pump A; 18. Air fan C; 19. Transformer cabinet 20. Hot water circulating pump B; 21. Heat exchanger; 22. Gas pipeline; 23. Gas pipeline valve; 24. Gas preheater inlet pipeline valve; 25. Gas preheater inlet pipeline; 26. Gas preheater outlet pipeline valve; 27. Gas preheater outlet pipeline; 28. Flue gas pipeline; 29. ​​Dehumidifier circulation pipeline; 30. Air pipeline A; 31. Air pipeline B; 32. Air pipeline C; 33. Gas boiler inlet water pipeline; 34. Gas boiler outlet water pipeline; 3 5. Gas boiler inlet water pipe valve; 36. Gas boiler outlet water pipe valve; 37. User-side hot water return main pipe; 38. Condenser inlet water pipe valve; 39. Condenser inlet water pipe; 40. Heat exchanger inlet water pipe valve A; 41. Heat exchanger inlet water pipe A; 42. Heat exchanger outlet water pipe valve; 43. Heat exchanger outlet water pipe; 44. Condenser outlet water pipe; 45. Condenser outlet water pipe valve A; 46. Condenser outlet water pipe valve B; 47. Hot water supply main pipeline on the user side; 48. Heat exchanger inlet water pipeline B; 49. Heat exchanger inlet water pipeline B valve; 50. Heat exchanger inlet water main pipeline; 51. User; 52. Second dehumidifying liquid circulation pipeline; 53. Third dehumidifying liquid circulation pipeline; 54. First air preheating pipeline; 55. Second air preheating pipeline; 56. First pipeline; 57. Second pipeline; 58. Third pipeline; 59. Fourth pipeline; 60. Transformer cabinet waste heat utilization pipeline; 61. Whitening pipeline. Detailed Implementation

[0024] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0025] Example 1, as Figure 1As shown, a dual-heat-source waste heat recovery and flue gas whitening system includes a user heating system, to which a gas-fired boiler hot water circulation system and an air-source heat pump hot water circulation system are connected; the gas-fired boiler hot water circulation system or the air-source heat pump hot water circulation system supplies heat to the user heating system independently, or the gas-fired boiler hot water circulation system and the air-source heat pump hot water circulation system are connected in series to supply heat to the user heating system, or the hot water circulation system and the air-source heat pump hot water circulation system are connected in parallel to supply heat to the user heating system; the gas-fired boiler hot water circulation system is equipped with a gas preheating system and a gas-fired boiler burner air preheating system; the air-source heat pump hot water circulation system is equipped with a transformer cabinet waste heat utilization system, the air-source heat pump hot water circulation system is connected to a flue gas waste heat utilization system, the gas preheating system and the gas-fired boiler burner air preheating system are respectively connected to the flue gas waste heat utilization system, and the flue gas waste heat utilization system is connected to a boiler flue gas whitening system. The gas-fired boiler hot water circulation system and the air-source heat pump hot water circulation system of this invention constitute a dual-energy complementary heating system. The heat source in the dual-energy complementary heating system is the condenser 14 and the gas-fired boiler body 1. Heat is generated through the gas-fired boiler hot water circulation system and the air-source heat pump hot water circulation system, and is delivered through the pipeline system and the valve switching to achieve four ways of supplying heat to user 51. The four ways of supplying heat to user 51 are: the gas-fired boiler hot water circulation system provides heat to user 51 alone; the air-source heat pump hot water circulation system provides heat to user 51 alone; the gas-fired boiler hot water circulation system and the air-source heat pump hot water circulation system are connected in parallel to provide heat to user 51; and the hot water generated by the air-source heat pump hot water circulation system is heated in stages by the gas-fired boiler hot water circulation system before being supplied to user 51. This invention enables the adjustment of heating modes based on economic efficiency. Furthermore, through a flue gas waste heat utilization system, it further utilizes waste heat to preheat the intake air and gas of the gas boiler hot water circulation system and the air source heat pump hot water circulation system, and to eliminate whitening of the exhaust flue gas. This maximizes resource utilization, prevents waste heat resources from being wasted, and helps to maximize the economic efficiency of the heating system. It solves the problems in the prior art where the heating mode of the heating system cannot be adjusted based on economic efficiency, waste heat resources are not fully utilized, and the economic efficiency cannot be maximized.

[0026] Example 2, based on Example 1, such as Figure 1As shown, a dual-heat-source waste heat recovery and flue gas whitening system is disclosed. The user heating system includes a user-side hot water return main pipe 37 and a user-side hot water supply main pipe 47, which are connected. The end of the user-side hot water supply main pipe 47 is connected to the condenser outlet water pipe 44 via a valve. The end of the user-side hot water return main pipe 37 is connected to the condenser inlet water pipe 39 via a valve. The middle section of the user-side hot water supply main pipe 47 is connected to the heat exchanger outlet water pipe 43 via a valve. The middle section of the user-side hot water return main pipe 37 is connected to... The heat exchanger inlet water main pipe 50 is also connected to the user-side hot water supply main pipe 47. The hot water supply main pipe 47, located between the user-side heat exchanger outlet water pipe 43 and the heat exchanger inlet water main pipe 50, is equipped with a condenser outlet water pipe valve B46. The condenser outlet water pipe 44 and the condenser inlet water pipe 39 are respectively connected to the air source heat pump hot water circulation system. The heat exchanger outlet water pipe 43 and the heat exchanger inlet water main pipe 50 are respectively connected to the outlet of the heat exchanger 21 on the side closer to the user 51 and the inlet on the side closer to 51 on the side closer to the user 51 on the gas boiler hot water circulation system. The user heating system consists of condenser 14, condenser inlet water pipe 39, condenser outlet water pipe 44, condenser inlet water pipe valve 38, condenser outlet water pipe valve A45, condenser outlet water pipe valve B46, user-side hot water return main pipe 37, user-side hot water supply main pipe 47, hot water circulation pump A17, heat exchanger outlet water pipe valve 42, heat exchanger outlet water pipe 43, heat exchanger inlet water pipe B48, heat exchanger inlet water pipe B valve 49, heat exchanger inlet water main pipe 50, heat exchanger inlet water pipe A valve 40, heat exchanger inlet water pipe A41, and user 51. The heat source for the user's heating system is a gas-fired boiler hot water circulation system and an air-source heat pump hot water circulation system. By switching the condenser inlet water pipe valve 38, the heat exchanger outlet water pipe valve 42, the condenser outlet water pipe valve A45, the condenser outlet water pipe valve B46, and the heat exchanger inlet water pipe valve B49, the user's heating system can be heated by either the gas-fired boiler hot water circulation system or the air-source heat pump hot water circulation system alone, or by connecting the gas-fired boiler hot water circulation system and the air-source heat pump hot water circulation system in series, or by connecting the hot water circulation system and the air-source heat pump hot water circulation system in parallel.

[0027] Example 3, based on Example 2, such as Figure 1As shown, a dual-heat-source waste heat recovery and flue gas whitening system is disclosed. The gas boiler hot water circulation system includes a gas boiler body 1 and a gas boiler burner 2, which are connected together. A gas pipeline 22 is connected to the gas boiler burner 2. A gas boiler inlet pipeline 33 and a gas boiler outlet pipeline 34 are connected to the gas boiler body 1, which are respectively connected to the boiler-side outlet and boiler-side inlet of the heat exchanger 21. The gas-fired boiler hot water circulation system consists of a gas-fired boiler body 1, a gas-fired boiler burner 2, an air pipeline A30, an air fan A9, an air heat exchanger 10, a gas pipeline 22, a gas pipeline valve 23, a gas preheater inlet pipeline valve 24, a gas preheater inlet pipeline 25, a gas preheater outlet pipeline valve 26, a gas preheater outlet pipeline 27, a gas preheater 3, a hot water circulation pump B20, a heat exchanger 21, a gas-fired boiler inlet water pipeline 33, a gas-fired boiler outlet water pipeline 34, a gas-fired boiler inlet water pipeline valve 35, and a gas-fired boiler outlet water pipeline valve 36. The gas preheated by the gas preheater 3 and the air preheated by the air heat exchanger 10 are mixed and burned in the gas-fired boiler burner 2, generating heat energy to heat the water in the gas-fired boiler body 1 to produce hot water at a certain temperature. This hot water is then supplied to user 51 through heat exchanger 21.

[0028] Example 4, based on Example 3, such as Figure 1 As shown, a dual-heat-source waste heat recovery and flue gas whitening system is disclosed. The gas preheating system includes a gas preheater 3, a gas pipeline 22, a gas pipeline valve 23, and a flue gas pipeline 28. The gas preheater 3 is connected in parallel to the gas pipeline 22. The gas preheater inlet valve 24 and the gas preheater outlet valve 26 are respectively installed at the inlet and outlet of the gas preheater 3. The gas pipeline valve 23 is installed on the gas pipeline 22 located between the inlet and outlet of the gas preheater 3. The gas preheater 3 is connected to the gas boiler body 1 via the flue gas pipeline 28. The gas preheating system consists of the gas pipeline 22, the gas pipeline valve 23, the gas preheater inlet valve 24, the gas preheater inlet pipe 25, the gas preheater outlet valve 26, the gas preheater outlet pipe 27, the flue gas pipeline 28, and the gas preheater 3. The gas in the gas pipeline 22 is partially or completely introduced into the gas preheater 3 by the regulation of the gas pipeline valve 23 and the gas preheater inlet pipeline valve 24. The gas is preheated by the flue gas from the flue gas pipeline 28. The preheated gas is mixed with the unpreheated gas and then enters the gas boiler burner 2 to be mixed with air and burned.

[0029] Example 5, based on Example 4, such as Figure 1As shown, a dual-heat-source waste heat recovery and flue gas whitening elimination system is disclosed. The gas-fired boiler burner air preheating system includes a solution dehumidifier B5, an air heat exchanger 10, an air duct A30, a first air preheating pipe 54, and a second air preheating pipe 55. The first inlet of the solution dehumidifier B5 is connected to the air duct A30, which is in communication with the air. The first outlet of the solution dehumidifier B5 is connected to the air heat exchanger 10 via the second air preheating pipe 55. The air heat exchanger 10 is connected to the gas-fired boiler burner 2 via the first air preheating pipe 54 and is in communication with the air via the air duct A30. The gas-fired boiler burner air preheating system consists of an air fan A9, an air heat exchanger 10, an air fan B11, and an air duct A30. Air heat exchanger 10 is connected to solution dehumidifier B5 via second air preheating pipe 55. Air in air pipe B31 absorbs heat from solution dehumidifier B5 and is transported to air heat exchanger 10 via air fan B11. After exchanging heat with air in air pipe A30, it is discharged into the atmosphere. Air in air pipe A30 is preheated and then transported to gas boiler burner 2 via air fan A9 to mix with gas for combustion. The waste heat sources in the circulating waste heat recovery are the heat in transformer cabinet 19 and the heat of boiler flue gas in gas boiler body 1.

[0030] Example 6, based on Example 5, such as Figure 1 As shown, a dual-heat-source waste heat recovery and flue gas whitening system is disclosed. The flue gas waste heat utilization system includes a solution dehumidifier A4, a solution dehumidifier B5, a regenerator 12, a flue gas pipeline 28, a first dehumidifying liquid circulation pipeline 29, a second dehumidifying liquid circulation pipeline 52, and a third dehumidifying liquid circulation pipeline 53. The solution dehumidifier A4 is connected to the first inlet of the regenerator 12 through the first dehumidifying liquid circulation pipeline 29, which is equipped with a dehumidifying liquid circulation pump 7. The first outlet of the regenerator 12 is connected to the solution dehumidifier B5 through the second dehumidifying liquid circulation pipeline 52. The solution dehumidifier B5 is connected to the solution dehumidifier B4 through the third dehumidifying liquid circulation pipeline 53. The solution dehumidifier B5 is connected to the air heat exchanger 10 through a second air preheating pipeline 55. The waste heat from the boiler flue gas is used partly to preheat the fuel gas and partly to heat the dehumidifying liquid. Part of the heat in the dehumidifying liquid is absorbed by the refrigerant in the regenerator 12, and the other part is used to preheat the air in the air heat exchanger 10.

[0031] Currently, the flue gas temperature of large boilers is generally maintained at around 125-150℃, which is relatively high. The flue gas requires a series of treatments before it can be discharged. The existing flue gas whitening technologies mainly include flue gas heating, flue gas cooling and condensation, and flue gas condensation and reheating. However, these methods are primarily for flue gas with an exhaust temperature of 125-150℃, and are complex. Furthermore, when the boiler flue gas waste heat is below 125℃ and insufficient to eliminate white plumes, a large amount of additional fuel gas or electricity is required for whitening, resulting in high system investment. The flue gas temperature involved in this invention is 50-80℃. Therefore, flue gas heating, flue gas cooling and condensation, and flue gas condensation and reheating methods are not suitable for flue gas waste heat utilization and plume elimination engineering applications under this condition. The transformers and flue gas waste heat involved in this invention are both low-grade waste heat, i.e., flue gas at 50-80℃. Existing treatment methods generally involve directly emitting the 50-80℃ flue gas into the atmosphere, which is not a full utilization of waste heat resources. Most existing technologies use heating to eliminate efflorescence, which consumes a lot of energy. This invention uses low-temperature solution cooling and dehumidification, and recycles the waste heat, which saves energy and increases efficiency. For the regeneration of the dehumidification solution, existing technologies use heating evaporation regeneration, which is energy-intensive. This invention uses air-cooled evaporation regeneration, which saves energy and increases efficiency. Compared with systems that use water source heat pumps to recover waste heat, this invention does not add high-value equipment such as large heat pumps, resulting in lower initial investment. Water source heat pump waste heat utilization systems are more suitable for the recovery and utilization of waste heat from large boiler flue gas, while this invention is more suitable for small and medium-sized systems.

[0032] This invention employs a cooling and dehumidification method to further utilize the waste heat of flue gas and eliminate smoke plumes. Boiler flue gas is transported through flue gas pipeline 28. In solution dehumidifier A4, the dehumidifying liquid is heated and humidified, changing the dehumidifying liquid from a concentrated solution to a dilute solution. The dilute dehumidifying liquid is then pumped to regenerator 12 by dehumidifying liquid circulation pump 7. In regenerator 12, some heat is transferred to the refrigerant before entering solution dehumidifier B5. In solution dehumidifier B5, mass transfer and heat exchange occur with outdoor cold air, and the solution is cooled and regenerated. The moisture in the solution transfers mass to the cold air for dehumidification, changing the dehumidifying solution from a dilute solution to a concentrated solution. The solution then enters solution dehumidifier A4 to continue the next cycle, thus recycling the waste heat in the flue gas.

[0033] Boiler flue gas is transported through flue gas pipe 28 to the solution dehumidifier A4 to heat and humidify the dehumidifying liquid, changing the dehumidifying liquid from a concentrated solution to a dilute solution. The dilute dehumidifying liquid is then transported to the regenerator 12 by the dehumidifying liquid circulation pump 7. After transferring some heat to the regenerator 12, it enters the solution dehumidifier B5 through the dehumidifying liquid circulation pipe 29. In the solution dehumidifier B5, it exchanges heat with the outdoor cold air and is cooled and dehumidified again, changing the dehumidifying liquid from a dilute solution to a concentrated solution, and then enters the solution dehumidifier A4 to continue the next cycle.

[0034] In the first stage of flue gas waste heat utilization, the fuel temperature in the gas boiler hot water circulation system is low in winter, affecting the energy efficiency of the gas boiler burner 2. A gas preheater 3 is used to heat the gas using flue gas waste heat, which not only utilizes the heat but also improves the combustion efficiency of the gas boiler burner 2. In the second stage of flue gas waste heat utilization, the heating performance of the air source heat pump hot water circulation system will decrease in the low temperature and high humidity environment in winter, and in severe cases, it will shut down for defrosting. The diluted solution from the solution dehumidifier A4 is circulated into the regenerator 12, and the heat enters the air source heat pump hot water circulation system, thus utilizing the waste heat for the second time and improving the heating performance of the air source heat pump hot water circulation system. In the third stage of flue gas waste heat utilization, the efficiency of the gas boiler burner 2 will decrease as the inlet air temperature decreases. The heated air from the solution dehumidifier B5 enters the air heat exchanger 10 and then enters the gas boiler burner 2, so that the gas boiler burner 2 receives air, and the waste heat is utilized for the third time, thus improving the efficiency of the gas boiler burner 2.

[0035] Example 7, based on Example 6, such as Figure 1 As shown, a dual-heat-source waste heat recovery and flue gas whitening elimination system is described. The boiler flue gas whitening elimination system includes a flue gas air cooler 8, which is connected to a solution dehumidifier A4 via a whitening elimination pipeline 61. Boiler flue gas is connected to a gas preheater 3, a solution dehumidifier A4, and the flue gas air cooler 8 via a flue gas pipeline 28. The boiler flue gas is preheated and cooled in the gas preheater 3, and then further cooled and dehumidified in the solution dehumidifier A4. The treated boiler flue gas is then introduced into the flue gas air cooler 8 through the whitening elimination pipeline 61 to exchange heat with outdoor air, further cooling and dehumidifying. After a series of treatments, the temperature and humidity of the boiler flue gas are significantly reduced, and no white smoke is produced after it is discharged into the atmosphere, thus achieving whitening elimination of boiler flue gas emissions. While effectively utilizing waste heat, it can effectively reduce the moisture content of the flue gas, effectively eliminating the "white smoke" in flue gas emissions.

[0036] The boiler flue gas is preheated and cooled in the gas preheater 3, and then cooled and dehumidified in the solution dehumidifier A4. Gas preheating can improve the boiler's thermal efficiency. The treated boiler flue gas is introduced into the flue gas air cooler 8 through the gas boiler flue gas fan 6 to exchange heat with the outdoor air, cooling and dehumidifying it. After the flue gas mixes with the outdoor cold air in the air cooler 8, the temperature and humidity of the boiler flue gas are significantly reduced, and no plume is generated after it is discharged into the atmosphere, thus achieving the elimination of white plumes in boiler flue gas emissions.

[0037] Example 8, based on Example 7, such as Figure 1As shown, a dual-heat-source waste heat recovery and flue gas whitening system is disclosed. The air-source heat pump hot water circulation system includes a regenerator 12, a compressor 13, a condenser 14, a throttling valve 15, and an evaporator 16. The evaporator 16 is connected to the second inlet of the regenerator 12, and the second outlet of the regenerator 12 is connected to the compressor 13. The outlet and inlet of the condenser 14 on the side away from the user 51 are connected to the compressor 13 and the evaporator 16, respectively. The throttling valve 15 is located between the condenser 14 and the evaporator 16. The air source heat pump hot water circulation system includes an evaporator 16. The evaporator 16 is connected to the second inlet of the regenerator 12 via a first pipe 56. The second outlet of the regenerator 12 is connected to a compressor 13 via a second pipe 57. The compressor 13 is connected to a condenser 14 via a third pipe 58. The condenser 14 is connected to the evaporator 16 via a fourth pipe 59, which is equipped with a throttling valve 15. The outlet and inlet of the condenser 14, which are closer to the user 51, are respectively connected to the condenser outlet water pipe 44 and the condenser inlet water pipe 39. The second inlet and second outlet of the regenerator 12 are connected by pipes to form one loop, and the first inlet and first outlet of the regenerator 12 form another loop. The two loops are not interconnected. The low-temperature, low-pressure refrigerant absorbs low-grade heat from the air in the evaporator 16, and continues to absorb heat from the dehumidifying liquid in the regenerator 12. The refrigerant is then boosted by the compressor 13. The high-temperature, high-pressure refrigerant condenses and releases heat in the condenser 14, producing high-grade hot water which is supplied to the user 51 through the pipeline system. The condensed refrigerant is then throttled and depressurized by the expansion valve 15 before entering the evaporator 16 to complete the next cycle.

[0038] Example 9, based on Example 8, such as Figure 1 As shown, a dual-heat-source waste heat recovery and flue gas whitening system is disclosed. The transformer cabinet waste heat utilization system is connected to the evaporator 16. The transformer cabinet waste heat utilization system includes a transformer cabinet 19, which houses the transformer in the air-source heat pump hot water circulation system. The transformer cabinet 19 is connected to the evaporator 16 via a transformer cabinet waste heat utilization pipe 60, and the transformer cabinet 19 is connected to the air via an air pipe C32. Air in the air pipe C32 enters the transformer cabinet 19, absorbs heat from the transformer cabinet, and the heated air is introduced into the evaporator 16 by an air fan C18 as a low-temperature heat source for the air-source heat pump hot water circulation system. When the outdoor ambient temperature is low, the transformer cabinet waste heat utilization system improves the operating conditions of the air-source heat pump, reduces the occurrence of frosting, and improves the energy efficiency of the transformer cabinet waste heat utilization system by utilizing the waste heat of the transformer.

[0039] An air fan A9 is installed on the first air preheating pipe 54 to facilitate the transfer of preheated air in the first air preheating pipe 54 to the gas boiler burner 2; an air fan B11 is installed on the second air preheating pipe 55 to facilitate the transfer of preheated air in the second air preheating pipe 55 to the air heat exchanger 10 for heat exchange; an air fan C18 is installed on the transformer cabinet waste heat utilization pipe 60, and the installation of the air fan C18 facilitates the transfer of hot air in the transformer cabinet 19 to the evaporator; a gas boiler flue gas fan 6 is installed on the whitening pipe 61, and the gas boiler flue gas fan 6 introduces the boiler flue gas into the flue gas air cooler 8 for heat exchange with the outdoor air.

[0040] Example 10, based on any one of Examples 1 to 9, such as Figure 1 As shown, a working method of a dual-heat-source waste heat recovery and flue gas whitening system includes the aforementioned dual-heat-source waste heat recovery and flue gas whitening system.

[0041] The specific operating method is as follows: When the gas-fired boiler hot water circulation system supplies heat independently, the gas preheating system, the gas-fired boiler burner air preheating system, the gas-fired boiler hot water circulation system, the boiler flue gas whitening system, and the boiler flue gas waste heat utilization system are all in operation. The hot water generated by the gas-fired boiler hot water circulation system is supplied to user 51 independently through the pipeline system. At this time, gas pipeline valve 23, gas preheater inlet pipeline valve 24, gas preheater outlet pipeline valve 26, gas boiler inlet water pipeline valve 35, gas boiler outlet water pipeline valve 36, heat exchanger inlet water pipeline valve A 40, and heat exchanger outlet water pipeline valve 42 are open, and the remaining valves are closed. This enables the gas-fired boiler hot water circulation system to supply heat to user 51 independently. The waste heat generated by the gas-fired boiler hot water circulation system is recovered and utilized by the gas preheating system, the gas-fired boiler burner air preheating system, and the boiler flue gas waste heat utilization system, and the whitening of the flue gas is achieved jointly by the boiler flue gas whitening system and the boiler flue gas waste heat utilization system.

[0042] When the air source heat pump hot water circulation system is supplying heat independently, both the transformer cabinet waste heat utilization system and the air source heat pump hot water circulation system are operational. The hot water produced by the air source heat pump hot water circulation system is supplied to user 51 independently through the piping system. At this time, valves 38 (condenser inlet water pipe), A45 (condenser outlet water pipe), and B46 (condenser outlet water pipe) are open, while the remaining valves are closed. This enables the air source heat pump hot water circulation system to supply heat to user 51 independently. Outdoor air is heated by the transformer cabinet waste heat utilization system and used as a low-temperature heat source for the air source heat pump hot water circulation system, improving its operational efficiency.

[0043] When the gas-fired boiler hot water circulation system and the air-source heat pump hot water circulation system are connected in parallel for heating, the gas preheating system, the gas-fired boiler burner air preheating system, the gas-fired boiler hot water circulation system, the transformer cabinet waste heat utilization system, the air-source heat pump hot water circulation system, the boiler flue gas whitening system, and the boiler flue gas waste heat utilization system are all in operation. The hot water produced by the gas-fired boiler hot water circulation system and the air-source heat pump hot water circulation system is supplied to user 51 through the pipeline system. At this time, gas pipeline valve 23, gas preheater inlet pipeline valve 24, gas preheater outlet pipeline valve 26, gas boiler inlet water pipeline valve 35, gas boiler outlet water pipeline valve 36, condenser inlet water pipeline valve 38, heat exchanger inlet water pipeline valve A 40, heat exchanger outlet water pipeline valve 42, condenser outlet water pipeline valve A 45, and condenser outlet water pipeline valve B 46 are open, and the remaining valves are closed. The return water from User 51's system is heated by both the gas-fired boiler hot water circulation system and the air-source heat pump hot water circulation system before being mixed and entering the supply pipeline, thus enabling the gas-fired boiler hot water circulation system and the air-source heat pump hot water circulation system to supply heat to User 51 in parallel. The waste heat from the flue gas generated by the gas-fired boiler hot water circulation system is recovered and utilized by the gas preheating system, the gas-fired boiler burner air preheating system, and the boiler flue gas waste heat utilization system. Flue gas whitening is eliminated by the combined boiler flue gas whitening system and the boiler flue gas waste heat utilization system. Outdoor air is heated by the transformer cabinet waste heat utilization system and used as a low-temperature heat source for the air-source heat pump hot water circulation system, improving the operating efficiency of the air-source heat pump hot water circulation system.

[0044] When the gas-fired boiler hot water circulation system and the air-source heat pump hot water circulation system are connected in series for cascade heating, the gas preheating system, the gas-fired boiler burner air preheating system, the gas-fired boiler hot water circulation system, the transformer cabinet waste heat utilization system, the air-source heat pump hot water circulation system, the boiler flue gas whitening system, and the boiler flue gas waste heat utilization system are all in operation. The hot water generated by the gas-fired boiler hot water circulation system and the air-source heat pump hot water circulation system is heated in series through the pipeline system to provide heat to user 51. At this time, valves 23 (gas pipeline), 24 (gas preheater inlet pipeline), 26 (gas preheater outlet pipeline), 35 (gas boiler inlet water pipeline), 36 (gas boiler outlet water pipeline), 38 (condenser inlet water pipeline), 42 (heat exchanger outlet water pipeline), A45 (condenser outlet water pipeline), and B49 (heat exchanger inlet water pipeline) are open, and the remaining valves are closed. The return water from user 51 is heated by the air source heat pump hot water circulation system, and then by the gas boiler hot water circulation system before entering the water supply pipeline. This achieves a series cascade heating system between the gas boiler hot water circulation system and the air source heat pump hot water circulation system to supply heat to user 51.

[0045] When actually providing heating, the choice of which of the above heating methods to select requires calculation, based on economic considerations. The calculation is as follows:

[0046] 1. Under partial load:

[0047] First, based on the gas price, electricity price, gas-to-heat conversion efficiency, and electricity-to-heat conversion efficiency, the economical gas-to-electricity price ratio for heating is obtained. Then, based on the economical gas-to-electricity price ratio for heating, the appropriate dual-energy complementary heating system operation mode is determined.

[0048] 2. At full load:

[0049] Based on the ratio of gas to electricity prices in terms of heating economics, determine which dual-energy complementary heating system operation mode should be adopted as the primary operation mode.

[0050] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A dual-heat-source waste heat recovery and flue gas whitening system, comprising a user heating system, characterized in that, The user heating system is connected to a gas-fired boiler hot water circulation system and an air-source heat pump hot water circulation system; the gas-fired boiler hot water circulation system or the air-source heat pump hot water circulation system supplies heat to the user heating system independently; or the gas-fired boiler hot water circulation system and the air-source heat pump hot water circulation system are connected in series to supply heat to the user heating system; or the gas-fired boiler hot water circulation system and the air-source heat pump hot water circulation system are connected in parallel to supply heat to the user heating system; the gas-fired boiler hot water circulation system is equipped with a gas preheating system and a gas-fired boiler burner air preheating system; the air-source heat pump hot water circulation system is equipped with a transformer cabinet waste heat utilization system, the air-source heat pump hot water circulation system is connected to a flue gas waste heat utilization system, the gas preheating system and the gas-fired boiler burner air preheating system are respectively connected to the flue gas waste heat utilization system, and the flue gas waste heat utilization system is connected to a boiler flue gas whitening system; The gas-fired boiler hot water circulation system includes a gas-fired boiler body, a gas-fired boiler burner installed on the gas-fired boiler body, and a gas pipeline connected to the gas-fired boiler burner; the inlet and outlet of the gas-fired boiler body are respectively connected to the outlet and inlet on the side of the heat exchanger furthest from the user. The gas preheating system includes a gas preheater, a gas pipeline, gas pipeline valves, and a flue gas pipeline. The gas preheater is connected in parallel to the gas pipeline. The gas preheater inlet pipeline valve and the gas preheater outlet pipeline valve are respectively installed at the inlet and outlet of the gas preheater. A gas pipeline valve is installed on the gas pipeline between the inlet and outlet of the gas preheater. The gas preheater is connected to the gas boiler body through the flue gas pipeline. The gas boiler burner air preheating system includes a solution dehumidifier B, an air heat exchanger, an air duct A, an air duct B, a first air preheating pipe, and a second air preheating pipe. The first inlet of the solution dehumidifier B is connected to the air duct B, which is in communication with the air. The first outlet of the solution dehumidifier B is connected to the first inlet of the air heat exchanger through the second air preheating pipe. The first outlet of the air heat exchanger is in communication with the atmosphere. The second outlet of the air heat exchanger is connected to the gas boiler burner through the first air preheating pipe. The second inlet of the air heat exchanger is in communication with the air through the air duct A. The flue gas waste heat utilization system includes a solution dehumidifier A, a solution dehumidifier B, a regenerator, a flue gas pipeline, a first dehumidifying liquid circulation pipeline, a second dehumidifying liquid circulation pipeline, and a third dehumidifying liquid circulation pipeline. The solution dehumidifier A is connected to the first inlet of the regenerator through the first dehumidifying liquid circulation pipeline, and a dehumidifying liquid circulation pump is installed on the first dehumidifying liquid circulation pipeline. The first outlet of the regenerator is connected to the solution dehumidifier B through the second dehumidifying liquid circulation pipeline, and the solution dehumidifier B is connected to the solution dehumidifier A through the third dehumidifying liquid circulation pipeline. Boiler flue gas is transported through flue gas pipelines. In solution dehumidifier A, the dehumidifying liquid is heated and humidified, changing from a concentrated solution to a dilute solution. The dilute dehumidifying liquid is then transported to the regenerator by a dehumidifying liquid circulation pump. In the regenerator, some heat is transferred to the refrigerant before entering solution dehumidifier B. In solution dehumidifier B, mass transfer and heat exchange occur with the outdoor cold air, and the solution is cooled and regenerated. The moisture in the solution transfers mass to the cold air to reduce humidity, and the dehumidifying solution changes from a dilute solution to a concentrated solution, then enters solution dehumidifier A to continue the next cycle. The boiler flue gas whitening system includes a flue gas air cooler. The flue gas outlet of the gas preheater is connected to the flue gas inlet of the solution dehumidifier A through a flue gas pipeline. The flue gas outlet of the solution dehumidifier A is connected to the flue gas air cooler through a whitening pipeline.

2. The dual-heat-source waste heat recovery and flue gas whitening system according to claim 1, characterized in that: The user heating system includes a user-side hot water return main pipeline and a user-side hot water supply main pipeline that are interconnected. The user-side hot water supply main pipeline and the user-side hot water return main pipeline are respectively connected to the outlet and inlet of the condenser on the user side. The user-side hot water supply main pipeline is respectively connected to the outlet and inlet of the heat exchanger on the user side. The user-side hot water return main pipeline is connected to the inlet of the heat exchanger on the user side. A condenser outlet water pipeline valve B is provided on the hot water supply main pipeline located between the outlet and inlet of the heat exchanger on the user side. The outlet and inlet of the condenser on the side away from the user are respectively connected to an air source heat pump hot water circulation system. The outlet and inlet of the heat exchanger on the side away from the user are respectively connected to a gas boiler hot water circulation system.

3. The dual-heat-source waste heat recovery and flue gas whitening system according to claim 2, characterized in that: The air source heat pump hot water circulation system includes a regenerator, a compressor, a condenser, a throttling valve, and an evaporator. The evaporator is connected to the second inlet of the regenerator, and the second outlet of the regenerator is connected to the compressor. The outlet and inlet of the condenser on the side away from the user are connected to the compressor and the evaporator, respectively. The throttling valve is located between the condenser and the evaporator.

4. The dual-heat-source waste heat recovery and flue gas whitening system according to claim 3, characterized in that: The waste heat utilization system of the transformer cabinet includes a transformer cabinet, which is connected to an evaporator and connected to the air through an air pipe C.

5. A method for operating a dual-heat-source waste heat recovery and flue gas whitening system, characterized in that, Used in the dual heat source waste heat recovery and flue gas whitening system as described in any one of claims 1 to 4.

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