Thermal power generation boiler feed water deoxidizing device and method

Abstract

The invention discloses a thermal power generation boiler feed water deoxygenization device and method, and the device comprises a degassing membrane assembly which comprises a tube shell and a degassing membrane arranged in the tube shell, the degassing membrane divides the tube shell into a liquid phase side and a gas phase side, the liquid phase side is provided with a liquid phase side inlet and a liquid phase side outlet, the gas phase side is provided with a gas phase side outlet, and the liquid phase side inlet is used for receiving water to be deoxygenized; an inlet of the vacuum pump is connected with the gas phase side outlet; an inlet of the first filter is connected with the liquid phase side outlet; the electrochemical deoxidization module comprises a shell with an inlet and an outlet, a negative and positive electrode group arranged in the shell and a power supply for supplying power to the negative and positive electrode group, the inlet of the shell is connected with the liquid phase side outlet, and the outlet of the shell is connected to a boiler water vapor system. According to the method, oxygen in boiler feed water is removed through multi-stage degassing membrane coupling electrochemistry, extra steam does not need to be consumed, and the corrosion rate of boiler equipment and pipelines can be greatly reduced without dosing.

Description

Technical Field

[0001] The present invention relates to the technical field of power water treatment, and particularly relates to a deaeration device and method for feed water of a thermal power generation boiler. Background Art

[0002] Oxygen corrosion is the most common and relatively serious corrosion in the thermal power generation boiler system. The forms of oxygen corrosion are generally ulcerative corrosion and small-hole type local corrosion. This kind of corrosion causes very serious damage to the strength of metal components. Therefore, in the process of boiler feed water treatment technology, deaeration is a very crucial link. Oxygen is the main corrosive substance in the boiler feed water system. The oxygen in the feed water system should be removed quickly. Otherwise, it will corrode the feed water system and components of the boiler. The generated corrosive substance iron oxide will enter the boiler, deposit or adhere to the boiler tube wall and heating surface, forming iron scale that is insoluble and has poor heat transfer. The corroded iron scale will cause pitting on the inner wall of the pipeline, increasing the resistance coefficient. When the pipeline corrosion is serious, even pipeline explosion accidents may occur. In order to eliminate the corrosion and harm of dissolved oxygen to the boiler steam-water system, it is stipulated that steam boilers with an evaporation capacity greater than or equal to 2 tons per hour and hot water boilers with a water temperature greater than or equal to 95 °C must be deaerated, and according to the different working pressures of the boilers, the dissolved oxygen in the feed water is required to be controlled within the qualified range.

[0003] At present, the main deaeration methods in thermal power plants are thermal deaeration, vacuum deaeration, chemical deaeration and analytical deaeration. The principle of thermal deaeration is to heat the boiler feed water to the boiling point, reduce the solubility of oxygen, and continuously release the oxygen in the water. Then, the oxygen generated on the water surface is removed together with the water vapor. In this way, various gases in the water (including free CO 2 , N 2 ) can be removed. The water after deaeration will not increase the salt content or the dissolved amount of other gases, and the operation control is relatively easy, and the operation is stable and reliable. This is also the most widely used and mature deaeration method. However, thermal deaeration has the problems of relatively large steam consumption and high energy consumption; vacuum deaeration is a medium-temperature deaeration technology. Vacuum deaeration can utilize low-grade waste heat and can use a jet heater to heat softened water. Compared with the thermal deaeration technology, its heating conditions have been improved, and the self-consumed steam volume in the boiler house has decreased, but most of the disadvantages of thermal deaeration still exist; chemical deaeration refers to using steel filings, sodium sulfite, hydrazine, etc. for deaeration. Among them, the deaeration effect of steel filings is less reliable. Sodium sulfite deaeration will increase the salt content of the boiler water, resulting in an increase in the blowdown volume and waste of heat, which is very uneconomical. Hydrazine has been gradually phased out due to its toxicity and volatility; the working principle of analytical deaeration is to strongly mix and contact the oxygen-free gas with the feed water to be deaerated, so that the oxygen dissolved in the water is resolved into the gas, and so on in a cycle to achieve the purpose of deoxygenating the feed water. This method does not increase the self-consumed steam in the boiler house, but the device adjustment is complex, and the sealing requirements for the pipeline system and the deaeration tank are relatively high. Summary of the Invention

[0004] In view of the problems existing in the prior art, the present invention provides a thermal power generation boiler feed water deaeration device and method, which uses a multi-stage degassing membrane coupled with electrochemistry to remove oxygen in the boiler feed water, without consuming additional steam and without adding chemicals, and can greatly reduce the corrosion rate of boiler equipment and pipelines.

[0005] To solve the above technical problems, the present invention is realized through the following technical solutions: According to a first aspect of the present invention, there is provided a thermal power generation boiler feed water deaeration device, comprising: A degassing membrane assembly, including a shell and a degassing membrane disposed inside the shell. The degassing membrane divides the shell into a liquid phase side and a gas phase side. The liquid phase side is provided with a liquid phase side inlet and a liquid phase side outlet, and the gas phase side is provided with a gas phase side outlet. The liquid phase side inlet is used to access the water to be deaerated. A vacuum pump, the inlet of which is connected to the gas phase side outlet. A first filter, the inlet of which is connected to the liquid phase side outlet. An electrochemistry deaeration module, including a housing with an inlet and an outlet, a cathode and anode electrode group disposed inside the housing, and a power supply for supplying power to the cathode and anode electrode group. The inlet of the housing is connected to the liquid phase side outlet, and the outlet of the housing is connected to the boiler water vapor system.

[0006] In a possible implementation manner of the first aspect, the thermal power generation boiler feed water deaeration device further includes an iron removal module, the inlet of which is connected to the outlet of the housing, and the outlet of the iron removal module is connected to the boiler water vapor system.

[0007] In a possible implementation manner of the first aspect, the thermal power generation boiler feed water deaeration device further includes a second filter, the inlet of which is connected to the outlet of the iron removal module, and the outlet of the second filter is connected to the boiler water vapor system.

[0008] In a possible implementation manner of the first aspect, the thermal power generation boiler feed water deaeration device further includes a gas-water separator connected to the outlet of the vacuum pump.

[0009] In a possible implementation manner of the first aspect, the thermal power generation boiler feed water deaeration device includes multiple stages of the degassing membrane assemblies, and the multiple stages of degassing membrane assemblies are connected in series. The liquid phase side outlet of the upper stage degassing membrane assembly is connected to the liquid phase side inlet of the lower stage degassing membrane assembly, the liquid phase side outlet of the last stage degassing membrane assembly is connected to the inlet of the housing, and the gas phase side outlet of each stage of degassing membrane assembly is connected to the inlet of the vacuum pump.

[0010] In a possible implementation of the first aspect, the yin-yang electrode group includes steel cathode plates and steel anode plates that are installed alternately in parallel at equal intervals. The steel anode plates are connected to the positive pole of the power supply, and the steel cathode plates are connected to the negative pole of the power supply.

[0011] In a possible implementation of the first aspect, the deaeration device for feed water of a thermal power generation boiler further includes a nitrogen purging system. A nitrogen inlet is provided on the gas phase side, and the nitrogen inlet is connected to the nitrogen purging system.

[0012] In a possible implementation of the first aspect, the degassing membrane uses a hollow fiber hydrophobic microporous membrane.

[0013] In a possible implementation of the first aspect, the power supply is a DC power supply.

[0014] According to the second aspect of the present invention, there is provided a method for deaerating feed water of a thermal power generation boiler, using the deaeration device for feed water of a thermal power generation boiler described above. The method includes: Introduce the water to be deaerated into the liquid phase side from the liquid phase side inlet, use the vacuum pump to evacuate the gas phase side to form an oxygen concentration difference, drive the dissolved oxygen in the water to be deaerated on the liquid phase side to cross the degassing membrane and enter the gas phase side. The water passing through the degassing membrane module is filtered by the first filter and then enters the shell of the electro-chemical deaeration module from the liquid phase side outlet. Use the power supply to supply power to the yin-yang electrode group. Under the action of the yin-yang electrode group, the remaining oxygen in the water is removed as an electron acceptor. The water passing through the electro-chemical deaeration module is input into the boiler water vapor system.

[0015] Compared with the prior art, the present invention has at least the following beneficial effects: A deaerator for feed water of a thermal power generation boiler provided by the present invention introduces the water to be deaerated into the liquid phase side from the liquid phase side inlet, uses a vacuum pump to evacuate the gas phase side to form an oxygen concentration difference, and drives the dissolved oxygen in the water to be deaerated on the liquid phase side to cross the degassing membrane and enter the gas phase side. The water passing through the degassing membrane module is filtered by a first filter and then enters the shell of the electro-chemical deaeration module from the liquid phase side outlet. A power supply is used to supply power to the anode and cathode electrode groups. Under the action of the anode and cathode electrode groups, the remaining oxygen in the water is removed as an electron acceptor. The water passing through the electro-chemical deaeration module is input into the boiler water vapor system. It can be seen that through the coupling effect of the multi-stage degassing membrane module and the electro-chemical deaeration module, the present invention realizes the efficient removal of oxygen in the boiler feed water. The degassing membrane module uses the oxygen concentration difference to drive the dissolved oxygen to cross the membrane from the liquid phase to the gas phase, and this process does not require additional steam consumption, greatly reducing the energy consumption. Before entering the electro-chemical deaeration module, the first filter is used to remove the impurities that may be contained in the water to avoid blocking the electro-chemical deaeration module and affecting the electro-chemical deaeration effect. The electro-chemical deaeration module further removes the remaining oxygen in the water through electrolysis. The whole process does not require adding medicine, avoiding the problems of increased salt content and increased sewage discharge brought by the traditional chemical deaeration method, and realizing energy conservation and environmental protection. The device of the present invention can effectively remove the dissolved oxygen in the boiler feed water, thereby greatly reducing the corrosion rate of boiler equipment and pipelines. The electro-chemical deaeration module can completely remove the remaining trace oxygen in the water, further improving the deaeration effect and ensuring the safe and stable operation of the boiler system.

[0016] In order to make the above objects, features and advantages of the present invention more obvious and understandable, the following specifically enumerates preferred embodiments and, in conjunction with the accompanying drawings, makes a detailed description as follows. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] In order to more clearly illustrate the technical solutions in the specific embodiments of the present invention, the following will briefly introduce the drawings required for use in the description of the specific embodiments. Obviously, the following drawings are some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0018] Figure 1 Schematic diagram of a deaerator for feed water of a thermal power generation boiler provided in Embodiment 1 of the present invention; Figure 2 Schematic diagram of a deaerator for feed water of a thermal power generation boiler provided in Embodiment 2 of the present invention; In the figure: 1 - water-oxygen separation membrane module; 101 - liquid phase side inlet; 102 - liquid phase side outlet; 103 - gas phase side outlet; 104 - nitrogen inlet; 2 - vacuum pump; 3 - electro-chemical deaeration module; 301 - shell; 302 - anode and cathode electrode groups; 303 - power supply; 4 - iron removal module; 5 - first filter; 6 - gas-liquid separator; 7 - second filter. Detailed implementation mode

[0019] To make the objectives, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are some, but not all, of the embodiments of the present invention. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the scope of protection of the present invention.

[0020] As Figure 1 shown, the embodiment of the present invention provides a deaeration device for feed water of a thermal power generation boiler, mainly to solve the deficiencies of existing deaeration technologies in terms of energy consumption, operation complexity, and environmental protection. The deaeration device for feed water of a thermal power generation boiler mainly includes a degassing membrane module 1, a vacuum pump 2, an electro-chemical deaeration module 3, and a first filter 5. The degassing membrane module 1 includes a shell and a degassing membrane disposed inside the shell. The degassing membrane divides the shell into a liquid phase side and a gas phase side. The liquid phase side is provided with a liquid phase side inlet 101 and a liquid phase side outlet 102, and the gas phase side is provided with a gas phase side outlet 103. The liquid phase side inlet 101 is used to connect the water to be deaerated. The inlet of the vacuum pump 2 is connected to the gas phase side outlet 103. The inlet of the first filter 5 is connected to the liquid phase side outlet 102. The electro-chemical deaeration module 3 includes a housing 301 with inlets and outlets, a cathode and anode electrode group 302 disposed inside the housing 301, and a power supply 303 for supplying power to the cathode and anode electrode group 302. The inlet of the housing 301 is connected to the outlet of the first filter 5, and the outlet of the housing 301 is connected to the boiler water vapor system.

[0021] Specifically, the degassing membrane of the degassing membrane module 1 is made of a high-performance hydrophobic polymer membrane material, such as polytetrafluoroethylene (PTFE) or polypropylene (PP). This membrane material has oxygen permeability and water impermeability, and can effectively promote the migration of dissolved oxygen in water to the gas phase side. The water to be deaerated is connected through the liquid phase side inlet 101, and is connected to the vacuum pump 2 through the gas phase side outlet 103 to form a negative pressure environment, accelerating the deaeration process of dissolved oxygen.

[0022] When deaerating water using the feedwater deaeration device for a thermal power generation boiler in this embodiment, start the vacuum pump 2 to pre-vacuum the gas phase side of the degassing membrane module 1 until the set vacuum degree is reached. At the same time, turn on the power supply 303 of the electro-chemical deaeration module 3 to preheat the electrodes to an appropriate operating temperature. Continuously inject the water to be deaerated through the liquid phase inlet 101 into the liquid phase side of the degassing membrane module 1, and the water forms a thin liquid film on the membrane surface. Under the action of the vacuum pump 2, a negative pressure environment is formed on the gas phase side, driving the dissolved oxygen to pass through the degassing membrane into the gas phase side, and then being pumped out and discharged by the vacuum pump. The water that has undergone preliminary deaeration flows out from the liquid phase outlet 102 and enters the first filter 5 to filter out possible impurities in the water, avoiding large particle impurities from blocking the electro-chemical deaeration module 3. The water filtered by the first filter 5 enters the housing 301 of the electro-chemical deaeration module 3. Under the action of the anode and cathode electrode group 302, the residual dissolved oxygen in the water is removed by oxidation as an electron acceptor. The water after being treated by the electro-chemical deaeration module 3 has a dissolved oxygen content that has reached the specified standard and is directly input into the boiler water vapor system through the outlet.

[0023] In an implementable manner, as Figure 1 shown, the feedwater deaeration device for a thermal power generation boiler further includes an iron removal module 4. The inlet of the iron removal module 4 is connected to the outlet of the housing 301, and the outlet of the iron removal module 4 is connected to the boiler water vapor system.

[0024] Specifically, the iron removal module 4 includes a strong magnetic iron removal housing and magnetic rods installed inside the strong magnetic iron removal housing. It should be noted that the number and arrangement of the magnetic rods are optimized according to the water treatment volume and the content of ferromagnetic substances to ensure the best iron removal effect. The inlet of the iron removal module 4 is connected to the outlet of the electro-chemical deaeration module 3 to ensure that the water after electro-chemical deaeration treatment can directly enter the iron removal module 4. The outlet of the iron removal module 4 is then connected to the boiler water vapor system to send the iron-removed water for use in the boiler.

[0025] In this embodiment, during the deaeration operation, start the vacuum pump 2 and the power supply 303 of the electro-chemical deaeration module 3 to ensure that the equipment is in a normal working state. After the water to be deaerated has been treated by the degassing membrane module 1 and the electro-chemical deaeration module 3, most of the dissolved oxygen has been removed. At this time, the water enters the iron removal module 4, and under the action of the strong magnetic iron removal housing and the magnetic rods, the ferromagnetic corrosion products (such as rust, iron oxide, etc.) in the water are adsorbed on the surface of the magnetic rods. The water after being treated by the iron removal module 4 has both a dissolved oxygen content and a ferromagnetic corrosion product content that have reached the specified standard and is directly input into the boiler water vapor system through the outlet.

[0026] In an implementable manner, as Figure 1 shown, the feedwater deaeration device for a thermal power generation boiler further includes a second filter 7. The inlet of the second filter 7 is connected to the outlet of the iron removal module 4, and the outlet of the second filter 7 is connected to the boiler water vapor system.

[0027] Specifically, the inlet of the second filter 7 is connected to the outlet of the iron removal module 4 to ensure that the water after iron removal treatment can directly enter the second filter 7. The outlet of the second filter 7 is connected to the boiler water vapor system to send the filtered water into the boiler for use.

[0028] In this embodiment, during the deaeration operation, the power supplies 303 of the vacuum pump 2 and the electro-chemical deaeration module 3 are started to ensure that the equipment is in a normal working state. After the deaerated water is sequentially treated by the degassing membrane module 1, the electro-chemical deaeration module 3, and the iron removal module 4, most of the dissolved oxygen and ferromagnetic corrosion products have been removed. At this time, the water enters the second filter 7, and under the action of the filter element, impurities such as suspended solids, colloids, microorganisms, and non-magnetic corrosion products in the water are further removed. For the water treated by the second filter 7, the contents of dissolved oxygen, ferromagnetic corrosion products, and non-magnetic corrosion products all meet the specified standards and are directly input into the boiler water vapor system through the outlet.

[0029] In an implementable manner, as Figure 1 shown, the thermal power generation boiler feed water deaeration device further includes a gas-liquid separator 6 connected to the outlet of the vacuum pump 2. The inlet of the gas-liquid separator 6 is connected to the outlet of the vacuum pump 2 to receive the gas-liquid mixture discharged from the vacuum pump 2. It should be understood that the gas outlet of the gas-liquid separator 6 is connected to the exhaust system for discharging the separated gas; the liquid outlet returns to an appropriate position in the system, such as the inlet of the degassing membrane module 1 or the inlet of the electro-chemical deaeration module 3, to realize the recycling of water.

[0030] In an implementable manner, as Figure 1 shown, the anode-cathode electrode group 302 includes steel cathode plates and steel anode plates that are alternately installed in parallel at equal intervals. The steel anode plates are connected to the positive pole of the power supply 303, and the steel cathode plates are connected to the negative pole of the power supply 303. Specifically, the anode-cathode electrode group 302 is composed of steel cathode plates and steel anode plates that are alternately installed in parallel at equal intervals. The cathode plates are connected to the negative pole of the power supply 303, and the anode plates are connected to the positive pole of the power supply 303. Under the action of the DC power supply, the anode plates can uniformly and efficiently lose electrons to generate ferromagnetic corrosion products such as F3O4, and at the same time, the residual oxygen in the water is removed as an electron acceptor.

[0031] In other words, the water to be deoxygenated enters from the inlet of the electrochemical deoxygenation module 3 and flows through the anode and cathode electrode groups 302 in sequence. Under the action of the DC power supply, the anode plate loses electrons to generate ferromagnetic corrosion products such as F3O4, and at the same time, the residual oxygen in the water is removed as an electron acceptor. The cathode plate receives electrons to form a reducing environment, which can further remove the dissolved oxygen in the water. After the water is treated by electrochemical deoxygenation, the dissolved oxygen content is greatly reduced, and a certain amount of ferromagnetic corrosion products are generated. The deoxygenated water enters the iron removal module 4, and the ferromagnetic corrosion products in the water are removed through the action of the strong magnetic iron removal housing and the magnetic rod. Subsequently, the water enters the second filter 7 to further remove impurities such as suspended solids, colloids, microorganisms, and non-magnetic corrosion products in the water.

[0032] In one implementable manner, as Figure 1 shown, the feed water deoxygenation device for a thermal power generation boiler further includes a nitrogen purging system. A nitrogen inlet 104 is provided on the gas phase side, and the nitrogen inlet 104 is connected to the nitrogen purging system.

[0033] Start the nitrogen purging system and adjust the flow control valve so that nitrogen enters the nitrogen inlet 104 of the degassing membrane module 1 at an appropriate flow rate. The water to be deoxygenated flows in the membrane channels of the degassing membrane module 1, while nitrogen enters the gas phase side of the degassing membrane module 1 in a cross-flow manner from the nitrogen inlet 104. Under the action of nitrogen purging, nitrogen dilutes and timely takes away the oxygen that crosses the membrane from the liquid phase side to the gas phase side of each stage of the degassing membrane module, accelerating the separation and removal of dissolved oxygen.

[0034] In one implementable manner, as Figure 1 shown, the feed water deoxygenation device for a thermal power generation boiler includes a multi-stage degassing membrane module 1. The multi-stage degassing membrane module 1 is connected in series. The liquid phase side outlet 102 of the upper-stage degassing membrane module 1 is connected to the liquid phase side inlet 101 of the lower-stage degassing membrane module 1. The liquid phase side outlet 102 of the last-stage degassing membrane module 1 is connected to the inlet of the housing 301. The gas phase side outlet 103 of each stage of the degassing membrane module 1 is connected to the inlet of the vacuum pump 2.

[0035] Specifically, the boiler feed water to be deoxygenated enters from the liquid phase side inlet 101 of the first-stage degassing membrane module in the multi-stage degassing membrane module. A combined mode of vacuum pumping and nitrogen purging is adopted. Nitrogen is introduced into the nitrogen inlet 104, and vacuum is pumped at the gas phase side outlet 103 near the liquid phase side inlet 101 of each stage of the membrane module, so that nitrogen purging and the water to be deoxygenated enter and pass through the degassing membrane module 1 in a cross-flow manner. Nitrogen is used to dilute and timely take away the oxygen that crosses the membrane from the liquid phase side of each stage of the degassing membrane module 1 to the vacuum side, achieving the purpose of removing most of the dissolved oxygen in the boiler feed water. The water treated by each stage of the degassing membrane module 1 enters the housing 301 of the electrochemical deoxygenation module 3 from the liquid phase side outlet 102 of the last-stage degassing membrane module 1. Under the action of the DC power supply, the steel anode plate loses electrons to generate F 3 O4 Ferromagnetic corrosion products such as 4 are removed, and the residual oxygen in the water is removed as an electron acceptor. The water further deoxygenated by the electrochemical deoxygenation module 3 enters the iron removal module 4. The ferromagnetic corrosion products generated during the electrochemical deoxygenation process are adsorbed by the magnetic rod and removed. The boiler feed water after being treated by the iron removal module 4 returns to the boiler water vapor system from the outlet of the iron removal module 4.

[0036] In one implementable manner, the degassing membrane is a hollow fiber hydrophobic microporous membrane, which is made of non-polar materials such as polytetrafluoroethylene and polyvinylidene fluoride, and has strong hydrophobicity. Water molecules cannot pass through its pores, while gas molecules in the water can pass through the pores driven by the concentration difference on both sides of the membrane.

[0037] Example 1 The device diagram of this example is shown in the appendix Figure 1 , and its main body includes a multi-stage degassing membrane assembly 1, a nitrogen purging system, a vacuum pump 2, a gas-water separator 6, an electrochemical deoxygenation module 3, a DC power supply, an iron removal module 4, a first filter 5, and devices such as connecting pipes and valves. The specific connection methods of each part are as follows: The boiler feed water to be deoxygenated is connected to the liquid-phase side inlet 101 of the first-stage degassing membrane assembly 1 of the multi-stage degassing membrane assembly of this example by a pipeline. Its liquid-phase side outlet 102 is connected to the liquid-phase side inlet 101 of the next-stage degassing membrane assembly 1. The liquid-phase side outlet 102 of the last-stage degassing membrane assembly 1 is connected to the inlet of the first filter 5. The outlet of the first filter 5 is connected to the inlet of the electrochemical deoxygenation module 3. The nitrogen inlet 104 is connected to a nitrogen source. The gas-phase side outlet 103 near the liquid-phase side inlet 101 is connected to the inlet of the vacuum pump 2. The outlet of the vacuum pump 2 is connected to the inlet of the gas-water separator 6. The exhaust gas of the gas-water separator 6 is directly discharged to the atmosphere; inside the housing 301 of the electrochemical deoxygenation module 3, a cathode and anode electrode group 302 is installed. The cathode plate and the anode plate are installed in parallel and alternately at equal intervals. The anode is connected to the positive pole of the DC power supply, and the cathode is connected to the negative pole of the DC power supply; the outlet of the electrochemical deoxygenation module 3 is connected to the inlet of the iron removal module 4. The outlet of the iron removal module 4 is connected to the boiler water vapor system, and a magnetic rod is installed inside the iron removal module 4.

[0038] The operation method of the device in this example is as follows: The boiler feed water to be deoxygenated enters from the liquid-phase side inlet 101 of the first-stage degassing membrane module 1 in the multi-stage degassing membrane module. A combined mode of vacuum pumping and nitrogen purging is adopted. Nitrogen is introduced into the nitrogen inlet 104 of each stage of the degassing membrane module 1, and vacuum is pumped at the gas-phase side outlet 103 near the liquid-phase side inlet 101 of each stage of the degassing membrane module 1, so that nitrogen purging and the water to be deoxygenated enter and pass through the degassing membrane module 1 in a cross-flow form. The nitrogen is used to dilute and timely carry away the oxygen that crosses the membrane from the liquid phase side to the gas phase side of each stage of the degassing membrane module, achieving the purpose of removing most of the dissolved oxygen in the boiler feed water. The extracted gas is discharged to the atmosphere, and the separated water can be recycled to systems such as the power plant industrial water system and the demineralized water preparation system that have no requirements for oxygen content; the water treated by each stage of the degassing membrane module enters the first filter 5 from the liquid-phase side outlet of the last-stage degassing membrane module to filter out possible impurities in the water, avoiding blockage of the electrochemical deoxygenation module 3 by large-particle impurities. The water filtered by the first filter 5 enters the housing 301 of the electrochemical deoxygenation module 3. Under the action of the DC power supply, the steel anode plate loses electrons to generate F 3 O 4 and other ferromagnetic corrosion products, and the residual oxygen in the water is removed as an electron acceptor. The water further deoxygenated by the electrochemical deoxygenation module 3 enters the iron removal module 4. The ferromagnetic corrosion products generated during the electrochemical deoxygenation process are adsorbed by the magnetic rod and removed. The boiler feed water treated by the strong iron removal module 4 returns to the boiler water vapor system.

[0039] In this embodiment, a total of three-stage series-connected degassing membrane modules 1 are set. The degassing membrane material is polytetrafluoroethylene (PTFE), with an outer diameter of the membrane filament of 300 μm and an inner diameter of 200 μm; the vacuum pump 2 is of the water-ring type, and the vacuum degree at the gas-phase side outlet of the degassing membrane module is controlled to be -92~-96 kPa; in the electrochemical deoxygenation module 3, the cathode of the anode and cathode electrode group selects a steel cathode plate, and the anode selects a steel anode plate, and the output voltage of the DC power supply is controlled to be 10 V; the magnetic rod inside the iron removal module 4 is made of neodymium magnet strong magnetic material. In this embodiment, the dissolved oxygen content of the boiler feed water entering the degassing membrane module is 500~700 μg / L, and after treatment, the dissolved oxygen in the water produced at the outlet of the iron removal module 4 drops to less than 10 μg / L.

[0040] Embodiment 2 The device diagram of this embodiment is shown in the appendix Figure 2 , and the difference from Embodiment 1 is that: in this embodiment, an additional set of two-stage degassing membrane modules 1 is provided for the boiler make-up water to carry out deoxygenation treatment on the boiler make-up water. In this embodiment, a second filter 7 is also installed at the outlet of the iron removal module 4 to further remove the corrosion products generated during the electrochemical deoxygenation process. Except for this, the rest of this embodiment is the same as that of Embodiment 1, so the connection method and operation method will not be described in detail again.

[0041] In this embodiment, the degassing membrane material of the two-stage series degassing membrane module 1 for boiler make-up water is polytetrafluoroethylene (PTFE), with a filament outer diameter of 300 μm and an inner diameter of 200 μm; the degassing membrane material of the three-stage series membrane module 1 for boiler feed water is polytetrafluoroethylene (PTFE), with a filament outer diameter of 300 μm and an inner diameter of 200 μm; the vacuum pump 2 is of the water ring type, and the vacuum degree at the gas-phase side outlet of the membrane module is controlled to be -92 to -96 kPa; for the cathode and anode groups of the cathode and anode electrode groups inside the electro-chemical deoxidation module 3, a steel cathode plate is selected for the cathode and a steel anode plate is selected for the anode, and the output voltage of the DC power supply is controlled to be 10 V; the magnetic rods inside the iron removal module 4 are made of neodymium magnet strong magnetic materials. In this embodiment, the dissolved oxygen content of the boiler feed water entering the degassing membrane module is 500 to 700 μg / L, and after treatment, the dissolved oxygen in the water produced at the outlet of the iron removal module 4 drops to less than 10 μg / L.

[0042] In the description of the present invention, it should be understood that the orientation or positional relationship indicated by the terms "upper", "lower", "bottom", "inner", "outer", etc. is based on the orientation or positional relationship shown in the drawings, and is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and thus should not be construed as a limitation of the present invention.

[0043] In addition, the terms "first" and "second" are only used for descriptive purposes and cannot be construed as indicating or implying relative importance or implicitly specifying the quantity of the indicated technical features. Thus, the features defined with "first" and "second" may explicitly or implicitly include at least one of such features. In the description of the present invention, the meaning of "a plurality" is at least two, such as two, three, etc., unless otherwise specifically defined.

[0044] In the present invention, unless otherwise clearly specified and limited, the terms "connected" and "coupled" should be understood in a broad sense. For example, it may be a fixed connection, a detachable connection, or an integral body; it may be a mechanical connection, an electrical connection, or communication with each other; it may be directly connected, or indirectly connected through an intermediate medium, and may be the internal connection or the interaction relationship between two elements, unless otherwise clearly limited. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0045] In the present invention, unless otherwise clearly defined and limited, the first feature being "on" or "under" the second feature may mean that the first and second features are in direct contact, or the first and second features are in indirect contact through an intermediate medium. Moreover, the first feature being "above", "over" and "on top of" the second feature may mean that the first feature is directly above or obliquely above the second feature, or merely indicates that the horizontal height of the first feature is higher than that of the second feature. The first feature being "under", "beneath" and "underneath" the second feature may mean that the first feature is directly below or obliquely below the second feature, or merely indicates that the horizontal height of the first feature is lower than that of the second feature.

[0046] In the present invention, the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples", etc. mean that the specific features, structures, materials, or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials, or characteristics described may be combined in any one or more embodiments or examples in a suitable manner. In addition, without contradiction, those skilled in the art may combine and combine the different embodiments or examples described in this specification and the features of different embodiments or examples.

[0047] Finally, it should be noted that the above-described embodiments are only specific embodiments of the present invention, used to illustrate the technical solutions of the present invention, rather than limiting it. The protection scope of the present invention is not limited thereto. Although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that: any person skilled in the art within the technical scope disclosed by the present invention can still modify the technical solutions recorded in the foregoing embodiments or can easily think of changes, or perform equivalent replacements on some of the technical features; and these modifications, changes or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present invention, and should all be covered by the protection scope of the present invention. Therefore, the protection scope of the present invention shall be subject to the protection scope of the claims.

Claims

1. A thermal power generation boiler feed water deoxygenation device, characterized in that: include: A degassing membrane assembly (1) comprises a tube shell and a degassing membrane arranged in the tube shell, wherein the degassing membrane separates the tube shell into a liquid phase side and a gas phase side, the liquid phase side is provided with a liquid phase side inlet (101) and a liquid phase side outlet (102), the gas phase side is provided with a gas phase side outlet (103), and the liquid phase side inlet (101) is used to receive water to be deoxygenated; A vacuum pump (2), wherein an inlet of the vacuum pump (2) is connected to the gas phase side outlet (103); A first filter (5), wherein an inlet of the first filter (5) is connected to the liquid phase side outlet (102); The electrochemical deoxygenation module (3) comprises a shell (301) provided with an inlet and an outlet, a positive and negative electrode group (302) arranged in the shell (301), and a power supply (303) for supplying power to the positive and negative electrode group (302), wherein the inlet of the shell (301) is connected to the outlet of the first filter (5), and the outlet of the shell (301) is connected to the boiler water vapor system.

2. A thermal power generation boiler feed water deoxygenation device according to claim 1, characterized in that: The thermal power generation boiler feed water deoxygenation device further comprises an iron removal module (4), the inlet of the iron removal module (4) being connected to the outlet of the shell (301), and the outlet of the iron removal module (4) being connected to the boiler water vapor system.

3. A thermal power generation boiler feed water deoxygenation device according to claim 2, characterized in that: The thermal power generation boiler feed water deoxygenation device further comprises a second filter (7), the inlet of the second filter (7) is connected to the outlet of the iron removal module (4), and the outlet of the second filter (7) is connected to the boiler water vapor system.

4. A thermal power generation boiler feed water deoxygenation device according to claim 1, characterized in that: The thermal power generation boiler feed water deoxygenation device also includes a gas-water separator (6) connected to the outlet of the vacuum pump (2).

5. A thermal power generation boiler feed water deoxygenation device according to claim 1, characterized in that: The feed water deoxygenation device for a thermal power generation boiler comprises a plurality of stages of the degassing membrane assemblies (1), wherein the plurality of stages of the degassing membrane assemblies (1) are connected in series, wherein the liquid phase side outlet (102) of the upper stage of the degassing membrane assembly (1) is connected to the liquid phase side inlet (101) of the lower stage of the degassing membrane assembly (1), the liquid phase side outlet (102) of the last stage of the degassing membrane assembly (1) is connected to the inlet of the shell (301), and the gas phase side outlet (103) of each stage of the degassing membrane assembly (1) is connected to the inlet of the vacuum pump (2).

6. A thermal power generation boiler feed water deoxygenation device according to claim 1, characterized in that: The positive and negative electrode groups (302) include steel cathode plates and steel anode plates that are alternately installed in parallel and at equal intervals. The steel anode plates are connected to the positive electrode of the power source (303), and the steel cathode plates are connected to the negative electrode of the power source (303).

7. A thermal power generation boiler feed water deoxygenation device according to claim 1, characterized in that: The thermal power generation boiler feed water deoxygenation device also includes a nitrogen purge system. The gas phase side is provided with a nitrogen inlet (104), and the nitrogen inlet (104) is connected to the nitrogen purge system.

8. A thermal power generation boiler feed water deoxygenation device according to claim 1, characterized in that: The degassing membrane is a hollow fiber hydrophobic microporous membrane.

9. A thermal power generation boiler feed water deoxygenation device according to claim 1, characterized in that: The power supply (303) is a direct current power supply.

10. A method for deoxygenating feed water for thermal power generation boilers, characterized in that: Using a thermal power generation boiler feed water deoxygenation device as claimed in any one of claims 1 to 9, the method comprises: The water to be deoxygenated is connected to the liquid phase side from the liquid phase side inlet (101), and the gas phase side is evacuated by the vacuum pump (2) to form an oxygen concentration difference, so as to drive the dissolved oxygen in the water to be deoxygenated on the liquid phase side to cross the degassing membrane and enter the gas phase side. The water passing through the degassing membrane assembly (1) is filtered by the first filter (5) and then enters the shell (301) of the electrochemical deoxygenation module (3) from the liquid phase side outlet (102). The power supply (303) is used to supply power to the anode and cathode electrode group (302). Under the action of the anode and cathode electrode group (302), the residual oxygen in the water is removed as an electron acceptor, and the water passing through the electrochemical deoxygenation module (3) is input into the boiler water vapor system.

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