Cascade waste heat recovery system based on membrane deoxidization

Abstract

The utility model discloses a stepped waste heat recovery system based on membrane deoxidization, which is characterized in that on the basis of source deoxidization, stepped preheating recovery and low-grade waste heat recovery are arranged, so that the energy utilization rate is improved. The boiler flue gas cascade flow direction assembly comprises a boiler, a dust remover, a desulfurizing tower, a condenser and a chimney, the boiler comprises a hearth, a steam pocket and a flue, and a superheater, an economizer and an air pre-heater are sequentially arranged in the outflow direction of the flue; the water step flow direction assembly comprises a chemical water station, a desalted water tank, a membrane deaerator, a deoxygenated water tank and a plurality of step warming and heating mechanisms; the superheated steam utilization assembly comprises a steam turbine and a generator; a flue output port of the boiler is connected with an inlet of the dust remover, an outlet of the dust remover is connected into an inlet of the desulfurizing tower after being cooled, an outlet of the desulfurizing tower is connected with a gas end input port of the condenser, and a gas end output port of the condenser is connected to the bottom of the chimney.

Description

TECHNICAL FIELD

[0001] The utility model relates to the technical field of waste heat recovery system, specifically is a kind of based on membrane deaeration's cascade waste heat recovery system. BACKGROUND

[0002] In the process of boiler feed water treatment, deoxygenation is a very key link, oxygen is the main corrosive substance of boiler feed water system, and the oxygen in the feed water system should be quickly removed, otherwise it can corrode the feed water system and components of the boiler, and the corrosive substance iron oxide can enter the boiler, deposit or adhere to the boiler pipe wall and heating surface, form the iron scale that is difficult to dissolve and heat transfer is poor, and the corroded iron scale can cause the inner wall of pipeline to appear point pit, and the resistance coefficient increases, and when the pipeline corrosion is serious, even pipe explosion accident can occur.

[0003] In the fields of electric power, steel, petroleum chemical industry and the like, there are still a large number of low-grade waste heat directly discharged, including latent heat of saturated wet flue gas after desulfurization, sensible heat of flue gas after dust removal, sensible heat of steam turbine condensate; The existing thermal deaerator is based on the deaeration principle of Henry's law, and a large amount of steam needs to be introduced for temperature rise deaeration, which not only wastes high-grade steam, but also cannot recover low-grade waste heat after temperature rise, and only the heat is wasted. CONTENT OF UTILITY MODEL

[0004] In view of the above problems, the utility model provides a kind of based on membrane deaeration's cascade waste heat recovery system, it is arranged on the basis of source deoxygenation cascade preheating recovery, recovers low-grade waste heat, to improve energy utilization.

[0005] A kind of based on membrane deaeration's cascade waste heat recovery system, it is characterized in that, it includes:

[0006] Boiler flue gas cascade flow direction component, it includes boiler, dust collector, desulfurization tower, condenser, chimney, the boiler includes hearth, steam drum, flue, the outflow direction of the flue is sequentially arranged with superheater, coal saving device, air preheater;

[0007] Water cascade flow direction component, it includes water treatment station, desalted water tank, membrane deaerator, deaerated water tank, several ladder temperature rise heating mechanisms;

[0008] And superheated steam utilization component, it includes steam turbine, generator;

[0009] The flue outlet of the boiler is connected to the inlet of the dust collector, the outlet of the dust collector is connected to the inlet of the desulfurization tower after temperature reduction, the outlet of the desulfurization tower is connected to the gas end input port of the condenser, and the gas end output port of the condenser is connected to the bottom of the chimney;

[0010] The water outputted from the water treatment station sequentially passes through the desalted water tank, the membrane deaerator, and then is connected to the water end inlet of the condenser, the water end outlet of the condenser is connected to the input port of the deaerated water tank, the output port of the deaerated water tank is connected to the initial stage input port of the several ladder temperature heating mechanisms, the high stage output port of the several ladder temperature heating mechanisms connects the water input end of the economizer, the water output end of the economizer is connected to the steam drum, the steam output end of the steam drum is connected to the steam input end of the superheater, the steam output end of the superheater is connected to the steam input end of the steam turbine, the steam turbine drives the generator to generate electricity, and the low-temperature steam of the steam turbine is connected to the corresponding heating mechanism of the several ladder temperature heating mechanisms to heat the deaerated water.

[0011] The gas input end of the membrane deaerator is connected to the nitrogen purging pipeline, and the gas output port of the membrane deaerator discharges the mixed gas of oxygen and nitrogen.

[0012] It is further characterized in that:

[0013] The several ladder temperature heating mechanisms include a low-pressure heater, a low-temperature economizer, and a high-pressure heater in sequence along the water flow direction, and a feed water pump is further arranged between the low-temperature economizer and the high-pressure heater;

[0014] The output port of the deaerated water tank is connected to the first medium input port of the low-pressure heater through a deaerated water pump, the first medium output port of the low-pressure heater is connected to the first medium input port of the low-temperature economizer, the first medium output port of the low-temperature economizer is connected to the first medium input port of the high-pressure heater through the feed water pump, and the first medium output port of the high-pressure heater is connected to the water input end of the economizer;

[0015] The steam outlet of the steam turbine includes a residual steam outlet that is not completely used and a used exhaust steam outlet, the residual steam outlet is connected to the second medium input port of the high-pressure heater, the second medium output port of the high-pressure heater is connected to the backflow port of the deaerated water tank, the exhaust steam outlet is connected to the condenser and then connected to the second medium input port of the low-pressure heater, and the second medium output port of the low-pressure heater is connected to the backflow port of the deaerated water tank;

[0016] A nitrogen sealing module is arranged at the top of the deaerated water tank, and the nitrogen sealing module transports nitrogen through a nitrogen pipeline;

[0017] The flue gas discharged by the dust remover is connected to the second medium input port of the low-temperature economizer, and the second medium output port of the low-temperature economizer further transports the flue gas to the inlet of the desulfurization tower;

[0018] The membrane deaerator comprises at least one set of deaeration membrane contactors, each set of deaeration membrane contactors comprises a contactor body, an oxygen-containing water inlet, deoxygenated water outlet, nitrogen gas inlet, waste gas exhaust, the water inlets and outlets of the several sets of deaeration membrane contactors are connected in series, the several sets of nitrogen gas inlets and waste gas exhausts are arranged in parallel, the oxygen-containing water inlet of the first-stage deaeration membrane contactor formed in series is the total water inlet, and the deoxygenated water outlet of the last-stage deaeration membrane contactor formed in series is the total water outlet.

[0019] A kind of based on membrane deaeration's step-by-step waste heat recovery process, it is characterized in that: it uses based on membrane deaeration's step-by-step waste heat recovery system, after being pretreated by chemical water station, desalted water is stored to desalted water tank for standby, is sent into membrane deaerator for deaeration treatment by desalted water pump, after deaeration, deoxygenated water is stored to deoxygenated water tank after absorbing the latent heat of saturated wet flue gas after desulfurization tower, deoxygenated water tank must be treated by nitrogen sealing module nitrogen sealing, deoxygenated water is absorbed after low-pressure heater after steam turbine does work, again, deoxygenated water is sent into high-pressure heater by feed water pump after absorbing part of waste heat of boiler exhaust flue gas by low-temperature coal economizer, through high-pressure heater, after steam turbine does work, steam turbine drives motor to generate electricity.

[0020] It is further characterized in that:

[0021] Through condenser, the condensation latent heat of saturated wet flue gas after desulfurization tower is recovered, which reduces the burden of high temperature of desulfurization tower slurry;

[0022] Through low-pressure heater and high-pressure heater, the waste heat of condensed water after steam turbine does work is recovered, and the dissolved oxygen in condensed water is not up to standard. After reducing the temperature, the condensed water is mixed with deoxygenated water in deoxygenated water tank to make the dissolved oxygen up to standard.

[0023] Through low-temperature coal economizer, the sensible heat of flue gas before desulfurization tower is recovered, which improves the thermal efficiency of boiler.

[0024] It is further characterized in that:

[0025] The water is heated to 35℃ by condenser and enters deoxygenated water tank, the temperature of water entering the first medium input port of low-pressure heater is 40℃-45℃, the temperature of water entering the first medium input port of low-temperature coal economizer is 45℃-50℃, the temperature of water entering the first medium input port of high-pressure heater is 65℃-70℃, the temperature of water entering the water input end of coal economizer is 104℃-158℃, the temperature of water flowing out of the water output end of coal economizer is 150℃-180℃, the temperature of steam discharged from the excess steam outlet of steam turbine is 150℃-180℃, and the temperature of water formed by condenser after steam discharged from the exhaust steam outlet of steam turbine is 50°-55℃; the temperature of water flowing into deoxygenated water tank through backflow port is 40℃-45℃.

[0026] The temperature of the flue gas flowing out of the flue is 130℃-140℃, the temperature of the flue gas flowing out of the dust collector is 120℃-130℃, the temperature of the flue gas flowing out of the low-temperature economizer is 95℃-105℃, the temperature of the flue gas introduced into the desulfurization tower by the induced draft fan to the condenser inlet is 55℃-60℃, and the temperature of the flue gas discharged after passing through the condenser is 50℃-55℃.

[0027] After passing through the membrane deaerator, the dissolved oxygen level at room temperature is <5 ppb.

[0028] Traditional thermal deaerators fluctuate with boiler load, resulting in unstable deaeration. To prevent cavitation at the feedwater pump inlet, the thermal deaerator must be placed at a high position. In contrast, the membrane deaerator in this system can be placed at a low position, making efficient use of space. This system can flexibly adjust the boiler feedwater temperature according to the boiler load, improving boiler thermal efficiency, and is stable and reliable. Users can perform ambient temperature deaeration at the source of demineralized water, eliminating the need for a thermal deaerator. High-quality steam is consumed at zero, significantly reducing operating costs. It eradicates the problems of feedwater pump inlet cavitation and oxygen corrosion in the delivery pipeline. The system operates stably, greatly saving on maintenance costs, and provides users with new ideas for reintegrating waste heat resources, optimizing the system, and improving efficiency and production. Attached Figure Description

[0029] Figure 1 This is a schematic block diagram of the system connection corresponding to this utility model;

[0030] Figure 2 This is the process route diagram corresponding to this utility model;

[0031] Figure 3 This is a schematic diagram of the membrane deaerator used in this utility model;

[0032] Figure 4 This is a schematic diagram of the deoxidation membrane contactor of this utility model;

[0033] The names corresponding to the serial numbers in the diagram are as follows:

[0034] Boiler 10, Furnace 11, Steam Drum 12, Flue 13, Superheater 14, Economizer 15, Air Preheater 16, Circulating Pump 17, Blower 18, Dust Collector 20, Desulfurization Tower 30, Induced Draft Fan 31, Condenser 40, Chimney 50, Water Treatment Station 60, Demineralized Water Tank 70, Demineralized Water Pump 71, Membrane Deaerator 80, Deoxygenated Water Tank 90, Deoxygenated Water Pump 91, Nitrogen Sealing Module 92, Low-Pressure Heater 100, Low-Temperature Economizer 110, Feedwater Pump 111, High-Pressure Heater 120, Nitrogen Pipeline 130, Steam Turbine 140, Generator 150, Condenser 160, Steam Trap 161, Nitrogen Purge Pipeline 170, Exhaust Gas Discharge Pipeline 180, Water Ring Vacuum Pump 181, Bypass Passage 190, Valve 191, Deoxygenated Membrane Contactor 200;

[0035] The contactor body 1, the oxygen-containing water inlet 2, the oxygen-removed water outlet 3, the nitrogen gas inlet 4, and the exhaust gas outlet 5. DETAILED DESCRIPTION

[0036] A step-by-step waste heat recovery system based on membrane oxygen removal, see Figures 1-4 , comprising a boiler flue gas step flow assembly, a water step flow assembly, and a superheated steam utilization assembly;

[0037] The boiler flue gas step flow assembly comprises a boiler 10, a dust remover 20, a desulfurization tower 30, a condenser 40, and a chimney 50. The boiler 10 comprises a hearth 11, a steam drum 12, and a flue 13. The flue 13 is sequentially provided with a superheater 14, an economizer 15, and an air preheater 16 in the flow direction. A circulating pump 17 injects air into the steam drum 12, and a blower 18 injects air into the air preheater 16.

[0038] The water step flow assembly comprises a water treatment station 60, a desalted water tank 70, a membrane oxygen remover 80, an oxygen-removed water tank 90, and a plurality of step-by-step temperature-raising heating mechanisms. The step-by-step temperature-raising heating mechanisms comprise a low-pressure heater 100, a low-temperature economizer 110, and a high-pressure heater 120 in sequence along the water flow direction. A feedwater pump 111 is further arranged between the low-temperature economizer 110 and the high-pressure heater 120.

[0039] The superheated steam utilization assembly comprises a steam turbine 140 and a generator 150.

[0040] The flue outlet of the boiler 10 is connected to the inlet of the dust remover 20. The flue gas discharged by the dust remover 20 is connected to the second medium inlet of the low-temperature economizer 110. The second medium outlet of the low-temperature economizer 110 delivers the flue gas to the inlet of the desulfurization tower 30. The outlet of the desulfurization tower 30 is connected to the induced draft fan 31, which is then connected to the gas end inlet of the condenser 40. The gas end outlet of the condenser 40 is connected to the bottom of the chimney 50.

[0041] The water output from the water treatment station 60 is sequentially connected to the water end inlet of the condenser 40 through the desalted water tank 70 and the membrane oxygen remover 80. A desalted water pump 71 is arranged between the desalted water tank 70 and the membrane oxygen remover 80. The water end outlet of the condenser 40 is connected to the input of the oxygen-removed water tank 90. The output of the oxygen-removed water tank 90 is connected to the first medium inlet of the low-pressure heater 100 through the oxygen-removed water pump 91. The first medium outlet of the low-pressure heater 100 is connected to the first medium inlet of the low-temperature economizer 110. The first medium outlet of the low-temperature economizer 110 is connected to the first medium inlet of the high-pressure heater 120 through the feedwater pump 111. The first medium outlet of the high-pressure heater 120 is connected to the water input end of the economizer 15.

[0042] The water output end of the coal economizer 15 is connected to the steam drum 12, the steam output end of the steam drum 12 is connected to the steam input end of the superheater 14, the steam output end of the superheater 14 is connected to the steam input end of the steam turbine 140, the steam turbine 140 drives the generator 150 to generate electricity, the steam outlet of the steam turbine 140 includes a residual steam outlet for incomplete use and a used exhaust steam outlet, the residual steam outlet is connected to the second medium input port of the high-pressure heater 120, the second medium output port of the high-pressure heater 120 is connected to the backflow port of the deaerated water tank 90, and the exhaust steam outlet is connected to the condenser 160, then connected to the trap 161, and then connected to the second medium input port of the low-pressure heater 100, and the second medium output port of the low-pressure heater 100 is connected to the backflow port of the deaerated water tank 90.

[0043] The gas input end of the membrane deaerator 80 is connected to the nitrogen purge pipeline 170, and the gas output port of the membrane deaerator 80 discharges the mixed gas of oxygen and nitrogen through the waste gas discharge pipeline 180.

[0044] The nitrogen sealing module 92 is arranged at the top of the deaerated water tank 90, the nitrogen sealing module 92 transports nitrogen through the nitrogen pipeline 130, the nitrogen pipeline 130 simultaneously transports nitrogen to the nitrogen purge pipeline 170, and the waste gas discharge pipeline 180 is also integrated with the water ring vacuum pump 181.

[0045] In specific implementation, the membrane deaerator 80 includes two groups of deoxygenation membrane contactors 200, each group of deoxygenation membrane contactors 200 includes a contactor body 1, an oxygen-containing water inlet 2, a deoxygenated water outlet 3, a nitrogen inlet 4, and a waste gas discharge outlet 5, the water inlets and outlets of the two groups of deoxygenation membrane contactors 80 are sequentially and serially connected, the nitrogen inlets 4 and the waste gas discharge outlets 5 of the two groups are arranged in parallel, the oxygen-containing water inlet of the first-stage deoxygenation membrane contactor formed in series is the total water inlet, and the deoxygenated water outlet of the second-stage deoxygenation membrane contactor formed in series is the total water outlet.

[0046] When the dissolved oxygen of the water at the front end of the water input port of the membrane deaerator 80 is less than 5 ppb, the water does not need to pass through the membrane deaerator 80, and the valve 191 on the bypass passage 190 is directly opened to enter the water end inlet of the condenser 40, when the dissolved oxygen of the water at the front end of the water input port of the membrane deaerator 80 is not less than 5 ppb, the valve 191 on the bypass passage 190 is closed, and the water flows into the water end inlet of the condenser 40 after passing through the membrane deaerator 80.

[0047] A step-by-step waste heat recovery process based on membrane deoxygenation is shown in Figure 2The application adopts a step waste heat recovery system based on membrane oxygen removal, and the desalted water after pretreatment by the water conditioning station is stored in a desalted water tank for standby, is pumped into a membrane oxygen remover for oxygen removal treatment, and is stored in an oxygen removal water tank after absorbing the saturated wet flue gas latent heat of a desulfurization tower through a condenser. The oxygen removal water tank needs to be subjected to nitrogen sealing module nitrogen sealing treatment, and the oxygen removal water absorbs the waste heat of the condensate of the exhaust steam of the steam turbine after work through a low-pressure heater, absorbs part of the waste heat of the boiler exhaust flue gas through a low-temperature coal economizer, and is then sent into a high-pressure heater through a feed water pump to absorb the exhaust steam waste heat after work of the steam turbine through the high-pressure heater. After the water is heated, it is sent into a boiler, and the target steam obtained after heating of the boiler is sent into a steam turbine for work. The steam turbine drives an electric motor to generate electricity.

[0048] The condenser recovers the condensation latent heat of the saturated wet flue gas after the desulfurization tower, and reduces the burden of the high temperature of the slurry of the desulfurization tower;

[0049] The low-pressure heater and the high-pressure heater recover the waste heat of the condensate of the exhaust steam of the steam turbine after work, the dissolved oxygen of the condensate is substandard, the temperature is reduced, and the dissolved oxygen is made standard by mixing the condensate with the oxygen removal water in the oxygen removal water tank;

[0050] The low-temperature coal economizer recovers the sensible heat of the flue gas before the desulfurization tower, and improves the thermal efficiency of the boiler.

[0051] In the specific implementation, the water is heated to 35℃ through the condenser and then enters the oxygen removal water tank, the temperature of the water entering the first medium input port of the low-pressure heater is 40℃-45℃, the temperature of the water entering the first medium input port of the low-temperature coal economizer is 45℃-50℃, the temperature of the water entering the first medium input port of the high-pressure heater is 65℃-70℃, the temperature of the water entering the water input end of the coal economizer is 104℃-158℃, the temperature of the water flowing out of the water output end of the coal economizer is 150℃-180℃, the steam discharged from the steam outlet of the steam turbine is 150℃-180℃, the temperature of the water formed after the steam discharged from the steam outlet of the steam turbine passes through the condenser is 50°-55℃, and the temperature of the water flowing in through the backflow port of the oxygen removal water tank is 40℃-45℃.

[0052] The temperature of the flue gas flowing out of the flue is 135℃, the temperature of the flue gas flowing out of the dust collector is 125℃, the temperature of the flue gas flowing out of the low-temperature coal economizer is 100℃, the temperature of the flue gas introduced into the inlet of the condenser by the induced draft fan of the desulfurization tower is 55℃-60℃, the temperature of the flue gas discharged after passing through the condenser is 50°-55℃, the dissolved oxygen of the water at normal temperature after passing through the membrane oxygen remover is less than 5ppb, when the dissolved oxygen of the water before the water input port of the membrane oxygen remover is less than 5ppb, the water does not need to pass through the membrane oxygen remover, and the valve on the bypass passage is directly opened to enter the water end inlet of the condenser, when the dissolved oxygen of the water before the water input port of the membrane oxygen remover is not less than 5ppb, the valve on the bypass passage is closed, and the water flows into the water end inlet of the condenser after passing through the membrane oxygen remover.

[0053] The conventional thermal deaerator fluctuates according to the fluctuation of the boiler load, the deaeration effect is unstable, in order to prevent the cavitation of the feed water pump inlet, the thermal deaerator must be placed at a high position; the membrane deaerator of the system can be placed at a low position, and the occupied space is reasonably utilized; the system can flexibly adjust the boiler feed water temperature according to the boiler load, improve the boiler thermal efficiency, and the system is stable and reliable; the user uses the system to deaerate at normal temperature at the source of desalted water, cancels the thermal deaerator, consumes 0 high-quality steam, greatly reduces the operation cost, roots out the problems of cavitation of the feed water pump inlet and oxygen corrosion of the conveying pipeline, and the system is stable in operation, greatly saves the operation and maintenance cost, and provides a new idea for the user to re-integrate the waste heat resources, optimize the system, improve the efficiency and increase the yield.

[0054] It is apparent for those skilled in the art that the present application is not limited to the details of the above exemplary embodiments, but can be implemented in other concrete forms without departing from the spirit or essential characteristics of the present application. Accordingly, the embodiments should be considered as exemplary and non-limiting, and the scope of the present application is defined by the appended claims rather than the above description, and thus all changes falling within the meaning and range of the equivalent elements of the claims are intended to be embraced in the present application. Any reference signs in the claims should not be considered as limiting the claims involved.

[0055] In addition, it should be understood that, although the present specification is described in terms of embodiments, not every embodiment contains only one independent technical solution, and the description manner of the specification is only for the sake of clarity, and those skilled in the art should consider the specification as a whole, and the technical solutions in each embodiment can be properly combined to form other embodiments that can be understood by those skilled in the art.

Claims

1. A membrane-based oxygen-depolarized step-heat recovery system, characterized by, It comprises: A boiler flue step flow assembly, comprising a boiler, a dust remover, a desulfurization tower, a condenser, a chimney, the boiler comprising a furnace, a steam drum, a flue, the flue being sequentially arranged with a superheater, an economizer, an air preheater in the flow direction; A water step flow assembly, comprising a water treatment station, a desalted water tank, a membrane deaerator, a deaerated water tank, and a plurality of step-by-step heating mechanisms; And a superheated steam utilization assembly, comprising a steam turbine and a generator; The flue outlet of the boiler is connected to the inlet of the dust remover, the outlet of the dust remover is connected to the inlet of the desulfurization tower after being cooled, the outlet of the desulfurization tower is connected to the gas end input port of the condenser, and the gas end output port of the condenser is connected to the bottom of the chimney; The water output from the water treatment station sequentially passes through the desalted water tank and the membrane deaerator, and is connected to the water end inlet of the condenser, the water end outlet of the condenser is connected to the input port of the deaerated water tank, the output port of the deaerated water tank is connected to the initial stage input port of the plurality of step-by-step heating mechanisms, and the high-order output port of the plurality of step-by-step heating mechanisms is connected to the water input end of the economizer, the water output end of the economizer is connected to the steam drum, the steam input end of the superheater is connected to the steam output end of the superheater, and the steam input end of the steam turbine is connected to the steam output end of the steam turbine. The gas input end of the membrane deaerator is connected to a nitrogen purging pipeline, and the gas output port of the membrane deaerator discharges oxygen-nitrogen mixed gas.

2. The membrane-based oxygen-depolarized step-heat recovery system of claim 1, wherein: The plurality of step-by-step heating mechanisms comprise a low-pressure heater, a low-temperature economizer, and a high-pressure heater sequentially arranged along the water flow direction, and a feedwater pump is further arranged between the low-temperature economizer and the high-pressure heater.

3. The membrane-based oxygen-depolarized step-heat recovery system of claim 2, wherein: The output port of the deaerated water tank is connected to the first medium input port of the low-pressure heater through a deaerated water pump, the first medium output port of the low-pressure heater is connected to the first medium input port of the low-temperature economizer, the first medium output port of the low-temperature economizer is connected to the first medium input port of the high-pressure heater through the feedwater pump, and the first medium output port of the high-pressure heater is connected to the water input end of the economizer.

4. The membrane-based oxygen-depolarized step-heat recovery system of claim 3, wherein: The steam outlet of the steam turbine comprises a residual steam outlet that is not fully used and a used exhaust steam outlet, the residual steam outlet is connected to the second medium input port of the high-pressure heater, the second medium output port of the high-pressure heater is connected to the backflow port of the deaerated water tank, and the exhaust steam outlet is connected to the condenser and then connected to the second medium input port of the low-pressure heater, and the second medium output port of the low-pressure heater is connected to the backflow port of the deaerated water tank.

5. The membrane-based oxygen-depolarized fuel cell system of claim 1, wherein: A nitrogen sealing module is arranged on the top of the deaerated water tank, and the nitrogen sealing module delivers nitrogen through a nitrogen pipeline.

6. The membrane-based oxygen-depolarized fuel cell system of claim 2, wherein: The flue gas discharged by the dust remover is connected to the second medium input port of the low-temperature economizer, and the second medium output port of the low-temperature economizer delivers the flue gas to the inlet of the desulfurization tower.

7. The membrane-based oxygen-depolarized fuel cell system of claim 1, wherein: The film oxygen remover comprises at least one set of deoxygenated film contactor, each set of deoxygenated film contactor comprises a contactor body, an oxygen-containing water inlet, deoxygenated water outlet, nitrogen gas inlet, waste gas exhaust, the water inlets and outlets of the several sets of deoxygenated film contactor are connected in series, the several sets of nitrogen gas inlets and waste gas exhausts are arranged in parallel, the oxygen-containing water inlet of the first-stage deoxygenated film contactor formed in series is the total water inlet, and the deoxygenated water outlet of the last-stage deoxygenated film contactor formed in series is the total water outlet.

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