Deoxidizing system of flue gas waste heat recycling technology

Abstract

The utility model belongs to environmental protection treatment, soft water purification and flue gas recycling technical field, especially for a kind of flue gas waste heat recycling technology's deoxidation system, including deoxidation system and flue gas heat exchange system;The deoxidation system includes water inlet tank, water inlet pump, filter, water inlet dissolved oxygen meter, membrane contactor, vacuum circulating pump, heat exchanger, circulating water tank, nitrogen source, the flue gas waste heat that originally possibly be wasted is used for heating desalted water, improves energy utilization, avoids resource waste, need not to add chemical reagent, reduces reagent purchase, storage and use cost, also avoids the water quality pollution problem and subsequent chemical waste liquid processing cost due to reagent residue;Meanwhile, relatively simple system structure reduces maintenance difficulty and cost, simplified process reduces complex operation process and equipment, improves the operation efficiency of entire deoxidation and heat exchange process.

Description

Technical Field

[0001] This utility model belongs to the field of environmental protection treatment, soft water purification and flue gas recovery and utilization technology, specifically relating to a deoxygenation system for flue gas waste heat recovery technology. Background Technology

[0002] Hot water boilers are widely used as heating sources in northern my country, but dissolved oxygen in the boiler water can cause numerous problems. On one hand, dissolved oxygen accelerates the oxidation of ferrous ions, forming iron oxide and other substances, leading to pipe corrosion, uneven heat transfer, and low heating efficiency in the boiler system. Oxygen corrosion can thin the walls of flue pipes and water-cooled pipes, and in severe cases, even cause them to rot, greatly threatening the safe and economical operation of the boiler. On the other hand, dissolved oxygen in the boiler water causes severe corrosion to the metals of the thermal system. Its products condense into copper and iron scale at high-temperature areas, leading to deterioration of heat transfer. In severe cases, it can cause deposits in the high-pressure cylinder of the steam turbine and tube rupture, reducing boiler efficiency and affecting normal operation.

[0003] Currently used methods for removing dissolved oxygen have many drawbacks: Thermal deoxygenation (physical deoxygenation): This method involves heating water to its boiling point to release oxygen. Although the principle is simple, it is energy-intensive and requires continuous heating; the equipment is large and the initial investment is high; the high-temperature environment may also accelerate equipment corrosion.

[0004] Chemical deoxygenation involves adding reducing agents to water to react with dissolved oxygen. However, agent residues may pollute the water, such as hydrazine, which is toxic and requires strict control. Long-term operating costs are high, and chemical waste liquid needs to be treated, resulting in significant environmental pressure.

[0005] Vacuum deoxygenation: Dissolved oxygen is released at low temperature by drawing a vacuum in a closed system. However, the equipment is complex, difficult to maintain, and the vacuum system is susceptible to leakage, resulting in low stability.

[0006] Catalytic resin deoxygenation: This method uses a resin loaded with a catalyst to promote the reaction of oxygen and hydrogen to produce water. However, it requires a continuous supply of hydrogen, which poses safety risks. The catalyst is also prone to poisoning and failure, resulting in high maintenance costs. Utility Model Content

[0007] This invention aims to solve the problems of high energy consumption, high cost, complex equipment, and water pollution in existing deoxygenation technologies. By studying demineralized water, a membrane deoxygenation system is used to reduce the dissolved oxygen content in the demineralized water to meet the boiler water supply requirements. The waste heat from the flue gas is fully utilized to exchange heat with the deoxygenated demineralized water, and the heated demineralized water is used as boiler feed water to improve the utilization rate of waste heat from the flue gas and achieve cost reduction and efficiency improvement.

[0008] System composition: This system consists of a deoxygenation system and a flue gas heat exchange system.

[0009] Deoxygenation System: Components include an inlet tank, inlet pump, filter, dissolved oxygen meter, membrane contactor, vacuum circulation pump, heat exchanger, circulating water tank, and nitrogen source. Demineralized water enters the inlet tank and is pumped into the downstream membrane treatment system. En route, it passes through a filter to remove impurities before entering the membrane contactor. An inlet dissolved oxygen meter is installed on the inlet pipeline to monitor the oxygen content of the inlet water in real time. A water-ring vacuum pump creates a vacuum environment within the membrane contactor, while nitrogen gas is simultaneously injected into the contactor using a nitrogen source. Based on the membrane contactor's process principle, oxygen in the demineralized water is expelled, reducing the oxygen content in the water. The water-ring vacuum pump is equipped with a circulating cooling system. Cooling circulating water from the circulating water tank is pumped into the water-ring vacuum pump, and the effluent exchanges heat with the heat exchanger before being pumped back into the circulating water tank, continuously providing cooling for the water-ring vacuum pump.

[0010] Flue gas heat exchange system: This includes equipment such as a flue gas heat exchanger, a booster pump, and a high-temperature dissolved oxygen meter. After deoxygenation, the demineralized water is boosted by the booster pump and then exchanges heat with the flue gas heat exchanger. The waste heat from the flue gas is used to raise the temperature of the demineralized water. The heated demineralized water is then pumped into the boiler for use. During transportation, the oxygen content is monitored in real time by a high-temperature dissolved oxygen meter to ensure safe boiler operation.

[0011] Working principle: In the deoxygenation system, a vacuum environment created by a water ring vacuum pump and nitrogen provided by a nitrogen source are used to remove oxygen from the deoxygenated water through a special process of the membrane contactor, reducing the dissolved oxygen content. In the flue gas heat exchange system, the waste heat of the flue gas is used to heat the deoxygenated water, raising its temperature to meet the boiler feedwater temperature requirements. Simultaneously, the dissolved oxygen meter monitors the oxygen content in real time throughout the process to ensure water quality safety. Compared with the prior art, the beneficial effects of this utility model are: Make full use of flue gas waste heat: Use the waste heat of flue gas that might otherwise be wasted to heat demineralized water, thereby improving energy utilization and avoiding resource waste.

[0012] Reduced operating and maintenance costs: No chemical reagents are required, reducing the costs of reagent procurement, storage and use, and avoiding water pollution problems caused by reagent residues and subsequent chemical waste treatment costs; at the same time, the relatively simple system structure reduces maintenance difficulty and cost.

[0013] Improved operational efficiency: The simplified process reduces complex operating procedures and equipment, thereby improving the overall operational efficiency of the deoxygenation and heat exchange process. Attached Figure Description

[0014] The accompanying drawings are provided to further illustrate the present invention and form part of the specification. They are used together with the embodiments of the present invention to explain the present invention, but do not constitute a limitation thereof. In the drawings: Figure 1 This is a schematic diagram of the deoxygenation system of a flue gas waste heat recovery technology according to this utility model; In the picture: 1. Inlet water tank; 2. Filter; 3. Inlet dissolved oxygen meter; 4. Water ring vacuum pump; 5. Heat exchanger; 6. Circulating water tank; 7. Membrane contactor; 8. Outlet dissolved oxygen meter; 9. High temperature dissolved oxygen meter; 10. Flue gas heat exchanger; 11. Booster pump; 12. Nitrogen source. Detailed Implementation

[0015] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present utility model, and not all embodiments. Based on the embodiments of the present utility model, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the protection scope of the present utility model. Example

[0016] like Figure 1 As shown; A deoxygenation system for flue gas waste heat recovery technology.

[0017] In this implementation plan: to solve the technical problems existing in the prior art, such as the "currently commonly used dissolved oxygen removal methods have many drawbacks" disclosed in the background art above: Thermal deoxygenation (physical deoxygenation): This method involves heating water to its boiling point to release oxygen. Although the principle is simple, it is energy-intensive and requires continuous heating; the equipment is large and the initial investment is high; the high-temperature environment may also accelerate equipment corrosion.

[0018] Chemical deoxygenation involves adding reducing agents to water to react with dissolved oxygen. However, agent residues may pollute the water, such as hydrazine, which is toxic and requires strict control. Long-term operating costs are high, and chemical waste liquid needs to be treated, resulting in significant environmental pressure.

[0019] Vacuum deoxygenation: Dissolved oxygen is released at low temperature by drawing a vacuum in a closed system. However, the equipment is complex, difficult to maintain, and the vacuum system is susceptible to leakage, resulting in low stability.

[0020] Catalytic resin deoxygenation: This method utilizes a resin carrying a catalyst to promote the reaction of oxygen and hydrogen to produce water. However, it requires a continuous supply of hydrogen, which poses safety risks. The catalyst is also prone to poisoning and failure, resulting in high maintenance costs. In practical terms, this is a real and difficult problem to solve. Therefore, to address this technical issue, a deoxygenation system based on flue gas waste heat recovery technology is proposed.

[0021] like Figure 1 As shown in the figure; Based on the above, the system includes a deoxygenation system and a flue gas heat exchange system. The deoxygenation system includes an inlet tank 1, an inlet pump, a filter 2, an inlet dissolved oxygen meter 3, a membrane contactor 7, a water ring vacuum pump 4, a heat exchanger 5, a circulating water tank 6, and a nitrogen source 12. The inlet tank 1 is connected to the filter 2 via the inlet pump, and the filter 2 is connected to the membrane contactor 7. The inlet dissolved oxygen meter 3 is installed on the pipeline between the inlet tank 1 and the filter 2. The water ring vacuum pump 4 is connected to the membrane contactor 7 to create a vacuum environment inside the membrane contactor 7, and the nitrogen source 12 is connected to the membrane contactor 7 to inject nitrogen gas into the membrane contactor 7.

[0022] The circulating water tank 6 is connected to the water ring vacuum pump 4 via a pipe, and a heat exchanger 5 is installed on the pipe between the circulating water tank 6 and the water ring vacuum pump 4. The flue gas heat exchange system includes a flue gas heat exchanger 10, a booster pump 11, a high-temperature resistant dissolved oxygen meter 9, and an effluent water meter 8. The outlet end of the membrane contactor 7 is connected to the flue gas heat exchanger 10 via the booster pump 11, and the outlet end of the flue gas heat exchanger 10 is connected to the boiler via a pipe. The high-temperature resistant dissolved oxygen meter 9 is installed on the pipe between the flue gas heat exchanger 10 and the boiler. The effluent water meter 8 is connected between the membrane contactor 7 and the booster pump 11.

[0023] The inlet pump is used to pump the demineralized water in the inlet tank 1 into the downstream membrane treatment system, and the filter 2 is used to filter impurities in the demineralized water.

[0024] The influent dissolved oxygen meter 3 is used to monitor the oxygen content of the influent water in real time, and the membrane contactor 7 is used to discharge oxygen from the demineralized water using the process principle.

[0025] The water ring vacuum pump 4 is used to extract the vacuum environment inside the membrane contactor 7 and is equipped with a circulating cooling system. The heat exchanger 5 is used to exchange heat with the cooling circulating water of the water ring vacuum pump 4.

[0026] The circulating water tank 6 is used to store cooling circulating water and continuously supply water to the water ring vacuum pump 4. The nitrogen source 12 is used to inject nitrogen into the membrane contactor 7 to assist in deoxygenation.

[0027] The booster pump 11 is used to increase the pressure of the deoxygenated demineralized water so that it can enter the flue gas heat exchanger 10, which is used to increase the temperature of the deoxygenated demineralized water by utilizing the waste heat of the flue gas.

[0028] The high-temperature resistant dissolved oxygen meter 9 is used to detect the oxygen content of demineralized water before it enters the boiler in real time, ensuring the safe use of the boiler.

[0029] Deoxygenation System Operation: First, inject demineralized water into the inlet tank. Turn on the inlet pump, allowing the demineralized water to pass through the filter sequentially, removing impurities and ensuring the water quality entering the membrane contactor. The inlet dissolved oxygen meter monitors the oxygen content of the inlet water in real time and provides data feedback for timely adjustments to subsequent operations. Start the water ring vacuum pump to extract air from the membrane contactor, creating a vacuum environment. Simultaneously, turn on the nitrogen source and introduce nitrogen gas into the membrane contactor. Inside the membrane contactor, oxygen in the demineralized water is expelled under the action of vacuum and nitrogen, achieving deoxygenation of the demineralized water. Cooling circulating water from the circulating water tank is continuously pumped into the water ring vacuum pump to cool the water. The cooled water exchanges heat with the heat exchanger and then flows back to the circulating water tank, ensuring stable operation of the water ring vacuum pump.

[0030] Flue gas heat exchange system operation: After deoxygenation, the demineralized water is pressurized by a booster pump and then enters the flue gas heat exchanger. The flue gas heat exchanger uses the waste heat of the flue gas to heat the demineralized water, raising its temperature. Before the demineralized water enters the boiler, its oxygen content is tested again using a high-temperature dissolved oxygen meter. Only when the oxygen content meets the boiler inlet water standard is it allowed to enter the boiler, ensuring safe boiler operation.

[0031] During the entire system operation, it is necessary to regularly check the operating status of each device, such as the filtration effect of the filter, the accuracy of the dissolved oxygen meter, and the working condition of each pump. Impurities in the filter should be cleaned in a timely manner, the dissolved oxygen meter should be calibrated, and faulty equipment should be repaired or replaced to ensure the continuous and stable operation of the system.

[0032] Finally, it should be noted that the above are merely preferred embodiments of this utility model and are not intended to limit the utility model. Although the utility model has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this utility model should be included within the protection scope of this utility model.

Claims

1. A deoxygenation system for flue gas waste heat recovery technology, characterized in that, It includes a deoxygenation system and a flue gas heat exchange system; the deoxygenation system includes an inlet tank (1), an inlet pump, a filter (2), an inlet dissolved oxygen meter (3), a membrane contactor (7), a water ring vacuum pump (4), a heat exchanger (5), a circulating water tank (6), and a nitrogen source (12); the inlet tank (1) is connected to the filter (2) through the inlet pump, the filter (2) is connected to the membrane contactor (7), and the inlet dissolved oxygen meter (3) is installed on the pipeline between the inlet tank (1) and the filter (2); the water ring vacuum pump (4) is connected to the membrane contactor (7) and is used to extract the vacuum environment inside the membrane contactor (7), and the nitrogen source (12) is connected to the membrane contactor (7) and is used to inject nitrogen into the membrane contactor (7).

2. The deoxygenation system for flue gas waste heat recovery technology according to claim 1, characterized in that, The circulating water tank (6) is connected to the water ring vacuum pump (4) through a pipe. A heat exchanger (5) is installed on the pipe between the circulating water tank (6) and the water ring vacuum pump (4). The flue gas heat exchange system includes a flue gas heat exchanger (10), a booster pump (11), a high-temperature resistant dissolved oxygen meter (9), and an effluent meter (8). The outlet end of the membrane contactor (7) is connected to the flue gas heat exchanger (10) through the booster pump (11). The outlet end of the flue gas heat exchanger (10) is connected to the boiler through a pipe. The high-temperature resistant dissolved oxygen meter (9) is installed on the pipe between the flue gas heat exchanger (10) and the boiler. An effluent meter (8) is connected between the membrane contactor (7) and the booster pump (11).

3. The deaeration system for flue gas waste heat recovery technology according to claim 1, characterized in that: The inlet pump is used to pump the demineralized water in the inlet tank (1) into the back-end membrane treatment system, and the filter (2) is used to filter impurities in the demineralized water.

4. The deaeration system for flue gas waste heat recovery technology according to claim 1, characterized in that: The dissolved oxygen meter (3) is used to monitor the oxygen content of the influent in real time, and the membrane contactor (7) is used to discharge oxygen from the demineralized water using the process principle.

5. The deaeration system for flue gas waste heat recovery technology according to claim 1, characterized in that: The water ring vacuum pump (4) is used to extract the vacuum environment inside the membrane contactor (7) and is equipped with a circulating cooling system. The heat exchanger (5) is used to exchange heat with the cooling circulating water of the water ring vacuum pump (4).

6. The deaeration system for flue gas waste heat recovery technology according to claim 1, characterized in that: The circulating water tank (6) is used to store cooling circulating water and continuously supply water to the water ring vacuum pump (4), and the nitrogen source (12) is used to inject nitrogen into the membrane contactor (7) to assist in deoxygenation.

7. The deaeration system for flue gas waste heat recovery technology according to claim 2, characterized in that: The booster pump (11) is used to increase the pressure of the deoxygenated demineralized water so that it can enter the flue gas heat exchanger (10). The flue gas heat exchanger (10) is used to utilize the waste heat of the flue gas to increase the temperature of the deoxygenated demineralized water.

8. The deaeration system for flue gas waste heat recovery technology according to claim 2, characterized in that: The high-temperature resistant dissolved oxygen meter (9) is used to detect the oxygen content of the demineralized water before it enters the boiler in real time, ensuring the safe use of the boiler.

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