A flue gas waste heat and moisture comprehensive recycling system

Abstract

This utility model provides a comprehensive flue gas waste heat and moisture recovery system, belonging to the field of boiler flue gas treatment technology. The technical problem it solves is that existing boiler flue gas treatment methods easily cause equipment corrosion and have low resource utilization rates. The comprehensive flue gas waste heat and moisture recovery system includes: a spray tower, the bottom of which is connected to the waste heat boiler in a gas-fired steam combined cycle unit, and a water distribution device is installed in the upper part of the spray tower; a first pipeline connecting the bottom and upper part of the spray tower from the outside, with an intermediate water pump installed on the first pipeline; a second pipeline connecting the first pipeline and the heat network return water pipeline, with a recovery water pump and a water quality adjustment device installed on the second pipeline; and a lithium bromide heat pump system, the evaporator side of which is connected to the first pipeline, and the condenser side of which is connected to the heat network return water pipeline. This system can realize the recovery of flue gas waste heat and the resource utilization of condensate, achieving energy saving and environmental protection.

Description

Technical Field

[0001] This utility model relates to the field of boiler flue gas treatment technology, and in particular to a flue gas waste heat and moisture integrated recovery system. Background Technology

[0002] The flue gas emission temperature of the waste heat boiler of the gas-fired steam combined cycle heating and power generation unit usually drops to 80-120℃, but still contains a large amount of latent heat of vaporization and condensate. Traditional indirect heat exchangers are prone to low-temperature corrosion, heat exchange surface contamination and condensate discharge, resulting in waste of energy and water resources.

[0003] Flue gas waste heat recovery and utilization is widely adopted by gas-fired power plants due to its high economic, energy-saving, and environmental benefits. It uses flue gas as a heat source, a heat pump as a cooling source, and heat transfer through intermediate water, significantly improving the unit's thermal efficiency. However, at the same time, the acidic components carried by the condensed flue gas accelerate the corrosion rate of the metal materials in the intermediate water system, shortening the equipment's lifespan. Furthermore, the circulating water volume gradually increases after flue gas condensation, with excess water primarily discharged, resulting in low utilization.

[0004] Existing technologies using direct spray condensation with intermediate water can improve heat exchange intensity to some extent, but the condensate is acidic and cannot be directly reused in the heating network; at the same time, the waste heat from low-temperature flue gas is of low quality and difficult to utilize effectively. Therefore, there is an urgent need for an integrated system that is compact, has high heat exchange efficiency, allows for the resource utilization of condensate, and enables the upgrading and utilization of waste heat. Utility Model Content

[0005] The technical problem this utility model aims to solve is that existing boiler flue gas treatment methods are prone to causing equipment corrosion and have low resource utilization. It provides a flue gas waste heat and moisture integrated recovery system. This flue gas waste heat and moisture integrated recovery system has a compact structure, is not easy to corrode equipment, has high heat exchange efficiency, realizes the recovery of flue gas waste heat and the resource utilization of condensate, saves energy and is environmentally friendly, and has good application prospects.

[0006] To solve the above-mentioned technical problems, the technical solution of this utility model is as follows: This utility model provides a comprehensive flue gas waste heat and moisture recovery system, comprising: The bottom of the spray tower is connected to the waste heat boiler in the gas-fired steam combined cycle unit, and a water distribution device is installed in the upper part of the spray tower. A first pipeline connecting the bottom and top of the spray tower from the outside is provided, and an intermediate water pump is installed on the first pipeline; A second pipeline connects the first pipeline and the heating network return water pipeline, and a recovery water pump and a water quality conditioning device are installed on the second pipeline; A lithium bromide heat pump system, wherein the evaporator side of the lithium bromide heat pump system is connected to the first pipeline, and the condenser side of the lithium bromide heat pump system is connected to the return water pipeline of the heating network.

[0007] Optionally, a liquid collection tank is provided at the bottom of the spray tower.

[0008] Optionally, a level gauge is installed at the bottom of the exterior of the spray tower.

[0009] Optionally, a thermometer is installed at the upper flue gas outlet of the spray tower.

[0010] Optionally, a pH meter is installed on the second pipeline.

[0011] Optionally, the flue gas waste heat and moisture integrated recycling system also includes an intelligent control and monitoring system, which is connected to a thermometer, a level gauge, a pH meter, an intermediate water pump, a recycled water pump, a water quality conditioning device, and a lithium bromide heat pump system.

[0012] Optionally, the water quality conditioning device includes a self-cleaning filter and a pH adjustment device arranged sequentially along the water flow direction.

[0013] Optionally, it also includes a steam-water heat exchanger located at the connection between the return water pipeline and the supply water pipeline of the heating network.

[0014] Optionally, a heating network circulating water pump is installed on the heating network water supply pipeline.

[0015] Optionally, the return water pipeline and the supply water pipeline of the heating network are connected to the primary heat exchange station respectively.

[0016] The above-described solution of this utility model has at least the following beneficial effects: (1) Flue gas and intermediate water directly contact each other for heat exchange in the spray tower, causing water vapor to condense and mix with the intermediate water. The mixed water is adjusted by the water quality conditioning device and then used as supplement water for the heating network circulating water. At the same time, the waste heat of flue gas is extracted by the lithium bromide heat pump system and used to heat the heating network circulating water, thereby realizing the comprehensive utilization of waste heat recovery of flue gas and condensate resource utilization. In addition, the first and second pipelines can prevent the mixed water from accumulating in the spray tower and avoid the corrosion of the spray tower by the mixed water. The water quality conditioning device can adjust the pH of the water and prevent the mixed water from corroding the subsequent heating network. (2) The flue gas and the intermediate water come into direct contact in the spray tower, so that the flue gas water vapor can be fully condensed and the condensate can be recovered; (3) The condensate and intermediate water are mixed and purified online through a water quality conditioning device to meet the heating network makeup water standard; (4) Use a lithium bromide heat pump system to recover low-temperature waste heat and use it to heat the circulating water of the heating network to improve the waste heat utilization rate; (5) The intelligent control and monitoring system can automatically monitor the entire process to ensure the safe, stable and energy-saving operation of the system. Attached Figure Description

[0017] Figure 1 This is a structural diagram of the flue gas waste heat and moisture integrated recycling system of this utility model; Figure 2 This is a flowchart of a lithium bromide heat pump system; Figure 3 This is a flowchart of the water quality regulation unit.

[0018] Figure label: 1-Spray tower; 2-Intermediate water pump; 3-Recovery water pump; 4-Water quality adjustment device; 5-Lithium bromide heat pump system; 6-Steam-water heat exchanger; 7-Heating network circulating water pump; 8-Primary heat exchange station; 9-Intelligent control and monitoring system; 10-Water distribution device; 11-Collection tank; 12-Level gauge; 13-pH meter; 14-Thermometer; 15-Gas-steam combined cycle unit; 16-Waste heat boiler; 17-First pipeline; 18-Heating network return water pipeline; 19-Second pipeline; 20-Heating network supply water pipeline; 21-Low-pressure cylinder; 22-High-medium-pressure cylinder; 23-Evaporator; 24-Absorber; 25-Generator; 26-Condenser; 27-Condensate; 28-Self-cleaning filter; 29-pH adjustment device; A - Intermediate water; B - Heating network water; C - Steam; D - Heating network water. Detailed Implementation

[0019] Exemplary embodiments of the present invention will now be described in more detail with reference to the accompanying drawings. While exemplary embodiments of the present invention are shown in the drawings, it should be understood that the present invention may be implemented in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided so that this invention will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art.

[0020] like Figure 1 As shown, an embodiment of this utility model proposes a comprehensive flue gas waste heat and moisture recovery system, comprising: The bottom of the spray tower 1 is connected to the waste heat boiler 16 in the gas-fired steam combined cycle unit 15, and a water distribution device 10 is installed in the upper part of the spray tower 1. A first pipe 17 connects the bottom and top of the spray tower 1 from the outside. An intermediate water pump 2 is installed on the first pipe 17. In the spray tower 1, the humid flue gas from the waste heat boiler 16 directly contacts and exchanges heat with the intermediate water from the water distribution device 10, so that the water vapor in the flue gas condenses, mixes with the intermediate water, and collects the waste heat in the flue gas, thereby raising the temperature of the intermediate water. The intermediate water utilizes the uninterrupted operation of the intermediate water pump 2 to achieve continuous recovery of waste heat and moisture from the flue gas. A second pipeline 19 connects the first pipeline 17 and the heating network return water pipeline 18. A recovery water pump 3 and a water quality conditioning device 4 are installed on the second pipeline 19. This structure constitutes a condensate reuse system. The recovery water pump 3 recovers part of the intermediate water of the mixed flue gas condensate. After being treated by the water quality conditioning device 4, it is used as the supplement water for the heating network circulating water in the heating network return water pipeline 18. The lithium bromide heat pump system 5 has its evaporator side connected to the first pipeline 17 and its condenser side connected to the heat network return water pipeline 18. The evaporator side of the lithium bromide heat pump system 5 exchanges heat with the intermediate water that has been heated by absorbing the waste heat of the flue gas, and the condenser side of the lithium bromide heat pump system 5 is connected to the heat network return water pipeline 18 to use the recovered heat to heat the circulating water of the heat network.

[0021] The lithium bromide heat pump system 5 has a conventional structure in the art, comprising an evaporator 23, an absorber 24, a generator 25, and a condenser 26. For example... Figure 2 As shown, the process of recovering waste heat in the lithium bromide heat pump system 5 is as follows: the evaporator 23 in the lithium bromide heat pump system 5 exchanges heat with the intermediate water A after absorbing the waste heat of the flue gas and raising its temperature. The waste heat then exchanges heat with the heating network water B through the absorber 24 and is converted into heat with steam C in the generator 25. Finally, the recovered heat is used to heat the heating network water B through the condenser 26.

[0022] For example, the water quality conditioning device 4 includes a self-cleaning filter 28 and a pH conditioning device 29 arranged sequentially along the water flow direction.

[0023] The second pipeline 19, the recovery water pump 3, the self-cleaning filter 28, the pH adjustment device 29, and the heating network return water pipeline 18 constitute a water quality adjustment unit. For example... Figure 3 As shown, the process of the water quality adjustment unit is as follows: condensate 27 enters the second pipeline 19 through the recovery water pump 3, and after being filtered by the self-cleaning filter 28 and pH adjusted by the pH adjustment device 29, it enters the heating network return water pipeline 18.

[0024] In a preferred embodiment, the flue gas waste heat and moisture integrated recycling system further includes a steam-water heat exchanger 6, located at the connection between the heat network return water pipeline 18 and the heat network supply water pipeline 20.

[0025] For example, a heating network circulating water pump 7 is installed on the heating network water supply pipeline 20.

[0026] For example, the return water pipeline 18 and the supply water pipeline 20 of the heating network are respectively connected to the primary heat exchange station 8.

[0027] The heating network circulating water system consists of a steam-water heat exchanger 6, a heating network return water pipeline 18, a heating network supply water pipeline 20, and a heating network circulating water pump 7. The heating network circulating water, which is preheated by the lithium bromide heat pump system 5, is then heated a second time by the steam-water heat exchanger 6 and sent to the city's primary heat exchange station 8 by the heating network circulating water pump 7. The primary heat exchange station 8 heats the secondary pipeline network through the heat exchanger, ultimately providing heat to users.

[0028] For example, a liquid collection tank 11 is provided at the bottom of the spray tower 1 for collecting condensate and intermediate water.

[0029] For example, a level gauge 12 is provided at the bottom of the outside of the spray tower 1 to detect the liquid level in the spray tower 1.

[0030] For example, a thermometer 14 is installed at the upper flue gas outlet of the spray tower 1 to detect the temperature of the flue gas discharged from the upper end.

[0031] For example, a pH meter 13 is installed on the second pipeline 19 to detect the pH value of the water after it has been adjusted by the water quality conditioning device 4.

[0032] For example, a recycling water pump 3, a water quality adjustment device 4, and a pH meter 13 are sequentially arranged along the water flow direction on the second pipeline 19.

[0033] In a preferred embodiment, the flue gas waste heat and moisture integrated recycling system further includes an intelligent control and monitoring system 9, which is connected to a thermometer 14, a level gauge 2, a pH meter 13, an intermediate water pump 2, a recycled water pump 3, a water quality conditioning device 4, and a lithium bromide heat pump system 5. The intelligent control and monitoring system 9 is used to collect real-time data on flue gas temperature, spray tower level, and recycled water pH, and to control the operating conditions of the intermediate water pump 2, recycled water pump 3, water quality conditioning device 4, and lithium bromide heat pump system 5.

[0034] This integrated flue gas waste heat and moisture recovery system includes a flue gas condensation device, an intermediate water circulation system, a condensate recovery system, a lithium bromide heat pump system 5, and an intelligent control and monitoring system 9. Flue gas and intermediate water directly exchange heat in the condensation device, causing water vapor to condense and mix with the intermediate water. The mixed water, after quality adjustment, serves as supplementary water for the heating network circulation. Simultaneously, flue gas waste heat is extracted through the lithium bromide heat pump system 5 and used to heat the heating network circulation water. This integrated flue gas waste heat and moisture recovery system features a compact structure, high heat exchange efficiency, and achieves both flue gas waste heat recovery and condensate resource utilization. It is energy-saving and environmentally friendly, and has promising application prospects.

[0035] For example, the high-pressure cylinder 22 in the gas-steam combined cycle unit 15 is connected to the steam-water heat exchanger 6, the lithium bromide heat pump system 5 and the low-pressure cylinder 21 respectively. A portion of the water vapor in the high-pressure cylinder 22 returns to the condensate system after heat exchange with the steam-water heat exchanger 6 and the lithium bromide heat pump system 5, while another portion of the water vapor enters the low-pressure cylinder 21.

[0036] The working principle of this flue gas waste heat and moisture recovery system is as follows: Flue gas generated during the operation of the waste heat boiler 16 enters the spray tower 1 in a counter-current manner. At the top of the tower, it directly contacts the intermediate water, which has been evenly distributed by the water distribution device 10, for heat exchange and condensation. The condensate produced after flue gas condensation mixes with the intermediate water and enters the collection tank 11. The cooled flue gas is then discharged into the atmosphere from the top of the spray tower 1. Through the continuous operation of the intermediate water pump 2, the absorbed flue gas condensate is continuously enriched in the collection tank 11. When the level gauge 12 reaches the set start value, the recovery water pump 3 starts operating, recovering part of the intermediate water mixed with the flue gas condensate. After being treated by the water quality conditioning device 4, it is used as supplementary water for the heating network circulation. The water quality conditioning device 4 includes a self-cleaning filter and a pH adjustment device along the water flow direction. Using the self-cleaning filter and pH adjustment device, suspended solids in the water can be removed and the pH value of the recovered water can be adjusted to ensure the quality of the recovered water meets the requirements. The water quality meets the power industry standards for heating network circulating water makeup water and can be directly added to the heating network circulating water. The intelligent control and monitoring system 9 controls the liquid level of the collection tank 11 by adjusting the operating parameters of the recovery water pump 3, monitors the pH meter 13 at the outlet of the water quality conditioning device 4, automatically controls the dosage of the water quality conditioning device 4 (e.g., adding alkali for neutralization) to ensure that the recovered water quality meets the standard requirements, monitors the operating parameters of the thermometer 14 and the lithium bromide heat pump system 5, and automatically adjusts the operating parameters of the intermediate water pump 2 to maximize the value of flue gas waste heat recovery. The high-pressure cylinder 22 in the gas-steam combined cycle unit 15 is connected to the steam-water heat exchanger 6, the lithium bromide heat pump system 5 and the low-pressure cylinder 21, respectively. A portion of the water vapor in the high-pressure cylinder 22 returns to the condensate system after heat exchange with the steam-water heat exchanger 6 and the lithium bromide heat pump system 5, while another portion of the water vapor enters the low-pressure cylinder 21.

[0037] Taking a 1×255MW 9E gas-fired combined cycle turbine unit as an example, two lithium bromide heat pump units were constructed, effectively recovering 24MW of waste heat from the flue gas. After adopting the integrated waste heat and moisture recovery system of this utility model, the following effects are achieved: (1) The flue gas temperature of the waste heat boiler decreased from 89℃ to 33℃, the intermediate water temperature increased from 28℃ to 38℃, a single lithium bromide heat pump absorbed 12MW of waste heat, and the circulating water temperature of the heating network increased from 43℃ to 76℃.

[0038] (2) After filtration and pH adjustment, the recycled water has pH=9.5~10.5, YD<0.1mmol / L, turbidity<1NTU, and Fe<0.5mg / L, which fully meets the requirements of the power industry standards. It can be directly added to the heating network circulating water, and the condensate resource recycling capacity is as high as 25,000 tons / heating season.

[0039] (3) Under back pressure conditions, with the input gas volume and output power remaining basically unchanged, the output heat is increased by more than 23%, and the total system efficiency is increased from about 82.5% to more than 91.9%.

[0040] (4) The annual heating capacity will increase by approximately 500,000 GJ, which can increase the heating area by approximately 1 million square meters and save 17.34 million Nm³ of natural gas. 3 / year, NO emissions reduction x 21.8 tons / year, collecting approximately 25,000 tons / year of condensate, reducing NO emissions. x 16%.

[0041] (5) By adding alkali to the intermediate water through the water quality adjustment device 4, the corrosion problem of acidic condensate on metals was completely solved, and the corrosion of pipes and equipment was <0.075mm / year.

[0042] The key features of this utility model include: (1) The intermediate water is in direct contact with the flue gas at the outlet of the waste heat boiler. The two phases have a large contact area and sufficient heat and mass exchange. The heat exchange end difference between the flue gas and the cooling water in the spray heat exchange can reach about 2℃, which is 60% lower than the traditional heat exchange temperature difference (5℃).

[0043] (2) After filtration and pH adjustment, the condensate has pH=9.5~10.5, YD<0.1mmol / L, turbidity<1NTU, and Fe<0.5mg / L, which fully meets the requirements of the power industry standard and can be directly added to the heating network circulating water, saving ≥90% of water.

[0044] (3) Under back pressure conditions, the flue gas emission temperature can be reduced to below 33°C. Under the premise that the input gas volume and output power remain basically unchanged, the output heat is increased by more than 23%, and the total system efficiency is increased from about 82.5% to more than 91.9%.

[0045] (4) It has achieved the integration of waste heat recovery, emission reduction and water resource recovery, reduced nitrogen oxide emissions by more than 10%, and recovered and utilized up to 25,000 tons of condensate water per heating season.

[0046] (5) By adding alkali to the intermediate water through the water quality adjustment device 4, the corrosion problem of acidic condensate on metals was completely solved, and the corrosion of pipes and equipment was <0.075mm / year.

[0047] (6) Automatic operation is achieved through the intelligent control and monitoring system 9, which has low temperature alarm, overpressure protection and water quality exceeding the standard discharge interlock function, and the operation is unattended.

[0048] The above description is the preferred embodiment of this utility model. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of this utility model, and these improvements and modifications should also be considered within the protection scope of this utility model.

Claims

1. A comprehensive flue gas waste heat and moisture recovery system, characterized in that, include: The bottom of the spray tower (1) is connected to the waste heat boiler (16) in the gas-fired steam combined cycle unit (15), and a water distribution device (10) is installed in the upper part of the spray tower (1). A first pipe (17) connecting the bottom and top of the spray tower (1) from the outside of the spray tower (1) is provided with an intermediate water pump (2). A second pipeline (19) connects the first pipeline (17) and the heat network return water pipeline (18), and a recovery water pump (3) and a water quality adjustment device (4) are installed on the second pipeline (19). A lithium bromide heat pump system (5) is provided, wherein the evaporator side of the lithium bromide heat pump system (5) is connected to the first pipeline (17), and the condenser side of the lithium bromide heat pump system (5) is connected to the heat network return water pipeline (18).

2. The flue gas waste heat and moisture integrated recovery system according to claim 1, characterized in that, A liquid collection tank (11) is provided at the bottom of the interior of the spray tower (1).

3. The integrated flue gas waste heat and moisture recovery system according to claim 2, characterized in that, A level gauge (12) is installed at the bottom of the outside of the spray tower (1).

4. The integrated flue gas waste heat and moisture recovery system according to claim 3, characterized in that, A thermometer (14) is installed at the flue gas outlet at the upper end of the spray tower (1).

5. The flue gas waste heat and moisture integrated recovery system according to claim 4, characterized in that, A pH meter (13) is installed on the second pipeline (19).

6. The integrated flue gas waste heat and moisture recovery system according to claim 5, characterized in that, It also includes an intelligent control and monitoring system (9), which is connected to a thermometer (14), a level gauge (12), a pH meter (13), an intermediate water pump (2), a recycling water pump (3), a water quality conditioning device (4), and a lithium bromide heat pump system (5), respectively.

7. The integrated flue gas waste heat and moisture recovery system according to claim 1, characterized in that, The water quality conditioning device (4) includes a self-cleaning filter (28) and a pH conditioning device (29) arranged sequentially along the water flow direction.

8. The integrated flue gas waste heat and moisture recovery system according to claim 1, characterized in that, It also includes a steam-water heat exchanger (6), located at the connection between the heat network return water pipeline (18) and the heat network supply water pipeline (20).

9. The flue gas waste heat and moisture integrated recovery system according to claim 8, characterized in that, A heating network circulating water pump (7) is installed on the heating network water supply pipeline (20).

10. The flue gas waste heat and moisture integrated recovery system according to claim 8, characterized in that, The return water pipeline (18) and the supply water pipeline (20) of the heating network are respectively connected to the primary heat exchange station (8).

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