CN218548493U - Device for generating electricity by utilizing methane in solid oxide fuel cell - Google Patents

Abstract

The utility model discloses an utilize marsh gas in device of solid oxide fuel cell electricity generation, the device include with solid oxide fuel cell's the gaseous access connection's of positive pole gaseous pipeline of anode, with solid oxide fuel cell's the gaseous access connection's of negative pole gaseous pipeline of cathode, be equipped with the marsh gas air-blower that is used for giving the gaseous pressurization of anode along the gaseous direction of delivery of anode on the gaseous pipeline of anode in proper order, a desulphurization unit for desorption sulphur impurity, the prereformer who adjusts gaseous constitution, a gas heater for heating gas, be equipped with the air-blower that is used for giving the gaseous pressurization of cathode along the gaseous direction of delivery of cathode on the gaseous pipeline of cathode in proper order, an air heater for heating air. The device and the method provided by the utility model improve the power generation efficiency of the methane and efficiently utilize the methane resource.

Description

Device for generating electricity by utilizing methane in solid oxide fuel cell

Technical Field

The utility model belongs to the solid oxide fuel cell field, concretely relates to utilize marsh gas in device of solid oxide fuel cell electricity generation.

Background

Biogas is a combustible gas produced by fermenting organic matters under the condition of air isolation (anaerobic environment) and proper temperature and pH value by microorganisms, is named as the biogas which is firstly found in marsh, belongs to secondary energy and is renewable energy. Besides direct combustion for cooking, drying agricultural and sideline products, heating, lighting and gas welding, the marsh gas can also be used as fuel of internal combustion engine and chemical raw material for producing methanol, formalin, carbon tetrachloride and the like. The feed liquid and the sediments discharged after the fermentation of the biogas device contain rich nutrient substances and can be used as fertilizer and feed.

The composition of the biogas is greatly changed due to the influence of factors such as the type of organic matters, environmental conditions, the type of microorganisms and the like, and the composition of the conventional biogas is shown in table 1 at present.

TABLE 1 typical biogas composition

The main component of methane is methane, an ideal gas fuel, which is colorless and odorless and can be combusted after being mixed with a proper amount of air. The calorific value of pure methane is 35900kJ/m ³ The calorific value of the biogas is about 20800-23600 kJ/m ³ . I.e. 1m ³ After the biogas is completely combusted, the heat which is equivalent to that provided by anthracite coal of 0.7kg can be generated. Compared with other fuel gases, the fuel gas has better anti-explosion performance, has the advantages of efficiency, energy conservation, safety, environmental protection and the like when used for generating electricity, and is a good clean fuel.

In recent years, with the development of economy in China, the demand for energy is more and more large, but the external dependence of petroleum in China exceeds 70%, the external dependence of natural gas exceeds 40%, and the current situation of the external dependence cannot meet the most basic energy safety demand. In addition, according to the requirements of fourteen five countries, the power generation installation for realizing renewable energy in 2025 accounts for more than 50% of the total installed proportion of Chinese electric power. However, the problems of intermittency of wind energy, solar energy and the like in China and uneven distribution of resources such as wind energy, solar energy and the like in China exist, so that development of a distributed power generation technology to improve energy utilization efficiency becomes a new trend in the future.

Solid Oxide Fuel Cells (SOFC) are a new generation of clean and efficient power generation technology. Chemical energy is directly converted into electric energy through electrochemical reaction. In the process of energy conversion, combustion and mechanical movement are avoided, the limitation of Carnot cycle is avoided, and the energy conversion efficiency is high. The power generation efficiency of the SOFC can reach 50% -70%, the waste heat taste is high, and the power generation efficiency can exceed 80% by combining with the cogeneration. The SOFC has high light power generation efficiency and wide fuel selectivity, and natural gas, petroleum gas, biogas, hydrogen, coal gas, methanol and the like can be used as raw materials. Therefore, SOFC is considered to be a very promising fuel cell.

At present, a single-fuel biogas generator set, a dual-fuel biogas-diesel generator set and the like are mainly adopted for biogas power generation, but the traditional power generation modes convert chemical energy into heat energy and mechanical energy and further convert the heat energy into electric energy. The power generation efficiency of the gas turbine in advanced countries exceeds 40 percent at present, and the power generation efficiency of the gas turbine in China only slightly exceeds 30 percent at present; the power generation efficiency of the gas internal combustion engine power generation device is 30-50%; the power generation efficiency of the steam turbine is about 20%. Therefore, the low power generation efficiency of the internal combustion engine and the gas turbine causes the problem of energy utilization waste. With the progress of technology, the power generation efficiency of internal combustion engines and gas turbines is improved, but the trend of change is that the power generation efficiency is increased and then becomes stable along with the increase of scale, and the power generation efficiency is more suitable for large-scale power stations. However, large-scale centralized power generation has the problems of high cost, large occupied area, power distribution loss and the like. The SOFC has flexible output power and high power generation efficiency which can reach more than 65 percent, is very suitable for distributed energy sources, and is a key development direction of the future countries. And the generating efficiency of the SOFC combined heat and power generation technology is much higher than that of the gas turbine combined use, and is about 70-90%. In summary, SOFC and SOFC cogeneration technologies are significantly advantageous from the standpoint of power generation efficiency and output.

SUMMERY OF THE UTILITY MODEL

Aiming at the problems of the prior art in the methane power generation, the utility model provides a device and a method for generating power by utilizing methane in a solid oxide fuel cell, which improve the methane power generation efficiency and efficiently utilize methane resources. In addition, the method for providing the water-carbon ratio and the temperature required in the process of methane reforming is improved. Current SOFC system adopts steam generator direct control water carbon ratio mostly, and the utility model discloses an anode tail gas endless mode except utilizing steam generator moisturizing during the initial period of driving, follow-up operation will not need the demand that external water just accorded with water carbon ratio. On the other hand the utility model discloses a radiant method heats reformer and the gas before reforming, has reduced the use of heat exchanger, makes the volume and the cost of equipment obtain optimizing.

According to the first embodiment of the present invention, a device for generating power by using biogas in a solid oxide fuel cell is provided, which comprises an anode gas delivery pipe connected to an anode gas inlet of a solid oxide fuel cell set, a cathode gas delivery pipe connected to a cathode gas inlet of the solid oxide fuel cell set, the anode gas delivery pipe is sequentially provided with a biogas blower for pressurizing anode gas along a delivery direction of the anode gas, a desulfurization device for removing sulfur impurities, a prereformer composed of adjustment gas, and a gas heat exchanger for heating gas, the cathode gas delivery pipe is sequentially provided with an air blower for pressurizing cathode gas along a delivery direction of the cathode gas, an air preheater for heating air, a steam inlet pipe is connected to an inlet of the prereformer or a water inlet pipe is connected to an inlet of the prereformer through a steam generator.

Further, an anode tail gas output pipeline of the solid oxide fuel cell group is divided into a first branch pipe and a second branch pipe after heat exchange through a gas heat exchanger, the first branch pipe is connected with an anode tail gas inlet of the combustor, the second branch pipe is connected with a gas inlet of the pre-reformer after passing through a temperature-resistant circulating device, a cathode tail gas output pipeline of the solid oxide fuel cell group is connected with a cathode tail gas inlet of the combustor, the cathode tail gas and the anode tail gas are combusted in the combustor to generate heat, and the combustion tail gas output pipeline of the combustor sequentially passes through (a high-temperature medium channel of) the air preheater and the tail gas heat recoverer and then is output to the outside of the system.

Further, the gas heat exchanger is one of a plate shell type or a plate fin type heat exchanger, preferably, an inlet of a low-temperature medium channel of the gas heat exchanger is connected with the anode gas conveying pipeline, and an outlet of a high-temperature medium channel is connected with the first branch pipe and the second branch pipe after passing through the pipeline.

Further, the pre-reformer is a tubular reactor, for example, the inside of the tube is filled with a catalyst, an anode gas conveying pipeline is connected with a tube side inlet, the anode gas conveying pipeline is connected with an anode inlet of the solid oxide fuel cell stack through a gas heat exchanger after being discharged from the pre-reformer, and the temperature of the pre-reformer is maintained through the radiation transfer of heat generated by the solid oxide fuel cell stack and a combustor.

Furthermore, the air preheater is one of a plate-shell type heat exchanger and a plate-fin type heat exchanger, a combustion tail gas output pipeline of the combustor is connected with a high-temperature medium channel inlet of the air preheater, and a cathode gas conveying pipeline after the outlet of the air blower is connected with a low-temperature medium channel inlet of the air preheater.

Furthermore, the tail gas heat recoverer is one of a plate-shell type heat exchanger and a plate-fin type heat exchanger, an outlet of a high-temperature medium channel of the air preheater is connected with an inlet of a high-temperature medium channel of the tail gas heat recoverer, an inlet of a low-temperature medium channel of the tail gas heat recoverer is connected with a domestic cold water input pipeline, an outlet of the low-temperature medium channel is connected with a domestic hot water output pipeline, and the tail gas heat recoverer recovers heat of burning tail gas to be used for heating domestic water.

Further, the temperature-resistant circulating equipment is one of a temperature-resistant circulating blower or a venturi tube. A second branch pipe of the anode tail gas output pipeline is connected with an inlet of the reformer after being merged with an anode gas conveying pipeline after being discharged from the desulphurization device after being discharged from the temperature-resistant circulating equipment; the first branch pipe of the anode tail gas output pipeline is connected with the part of the combustor subjected to heat exchange, so that a part of anode tail gas is mixed with fuel flow coming from the outside after passing through the circulating equipment and enters the reformer; and the rest anode tail gas enters the combustor along the pipeline to be combusted and release heat. The temperature-resistant circulating equipment has the functions of circulating part of the unused fuel and the generated steam back to the reformer so as to achieve the effect of adjusting the water-carbon ratio in the reforming process, simultaneously improving the utilization rate of the fuel, avoiding the problem of carbon deposition in the reformer and preventing the fuel cell from being hot cracked.

Further, the radiant heating section is applied to the pre-reformer and the pre-reforming gas heating, and the solid oxide fuel cell stack, the burner and the pre-reformer are annularly distributed, wherein the pre-reformer is arc-shaped, the burner is located inside the pre-reformer, and the solid oxide fuel cell stack is located outside the pre-reformer, i.e. the pre-reformer and part of the inlet pipe thereof (i.e. the pipe section of the anode gas conveying pipe between the outlet of the desulfurizer and the inlet of the pre-reformer on the side close to the inlet of the pre-reformer) is located between the solid oxide fuel cell stack and the burner, preferably, the distance between the solid oxide fuel cell stack and the pre-reformer is generally 0.2-1.0m, preferably 0.2-0.5 m, preferably 0.3m-0.4m, and the distance between the pre-reformer and the burner is generally 0.2-0.8m, preferably 0.2m-0.4m, preferably 0.25m-0.35m; the distance between the solid oxide fuel cell stack and the burner is 0.3-1.2m, preferably 0.4-0.9m, preferably 0.55-0.75m.

Preferably, the outer wall of the pre-reformer and part of its inlet duct is made of a material that absorbs heat well (e.g. a metallic material such as steel or copper) to achieve heat collection and conduction.

Preferably, a housing, preferably made of a heat insulating material, is provided outside the solid oxide fuel cell stack, the pre-reformer, and a portion of the inlet duct and the burner, and is preferably sealed to keep heat from being lost to the outside. The reforming temperature and gas temperature can then be adjusted by varying the distance between the components.

The desulfurization unit, the prereformer, etc. may employ those known in the art.

The cathode raw material gas is provided by a fuel supply unit, the biogas is dedusted and then enters a desulfurization device R102 along a pipeline through a blower C101, and the biogas is desulfurized at normal temperature to obtain fuel gas (the sulfur content is lower than 0.1 ppm) required by power generation. The fuel gas is mixed with a portion of the anode tail gas (i.e., the "recycle gas") from the cell anode, preheated by radiation from the cell (SOFC) and the burner (a 101), and fed to the pre-reformer, where the heat generated by the cell and burner is used to continuously provide the desired temperature (e.g., 400 c to 500 c) for reforming. The pre-reformed gas enters a gas heat exchanger and enters the anode of the solid oxide fuel cell stack after reaching, for example, 600 ℃ to 750 ℃.

The steam generator is a movable device and mainly used for adjusting the water-carbon ratio of fuel gas at the initial start-up stage, and the water-carbon ratio is too low, so that the pre-reforming catalyst generates coking and carbon deposition; too high a water to carbon ratio ensures that pre-reforming is safe, but the cell operating voltage will drop, accelerating the rate of decay of the cell anode.

According to a second embodiment of the present invention, there is provided a method for generating biogas by using the above apparatus, the method comprising:

(1) The biogas is dedusted, pressurized by a biogas blower to 3-10kPa (further 4-8kPa, e.g. about 6 kPa), and then enters a desulfurization unit along a pipeline, desulfurized by normal temperature to obtain fuel gas (sulfur content can be as low as 0.1ppm below) required for power generation, preheated along a pipeline to 200-350 ℃ (further 250-320 ℃, e.g. about 300 ℃), steam is fed through a steam generator at the beginning of the reaction, and then mixed with recycle gas (a part of anode tail gas output from the anode of the solid oxide fuel cell stack, the volume ratio of fuel gas from the desulfurization unit to recycle gas can be 0.3-1.5, preferably 0.4-1.2 ℃), the water-carbon ratio is adjusted to 1.5-3 (further 1.8-2.5, preferably about 1), and then enters a pre-reformer, and the heat generated by the solid oxide fuel cell stack and the combustor is radiated to maintain the reforming temperature of 350-500 ℃, further comprising about 480 ℃ of nickel-based catalyst: 16% -19%, la:2% -5%, the pre-reformed gas enters the anode of the solid oxide fuel cell stack after being subjected to heat exchange by a gas heat exchanger to 600-750 ℃ (further 650-710 ℃, for example, about 700 ℃);

(2) Air is compressed by an air blower at 3-10kPa (preferably 6 kPa) and fed to an air preheater, preheated to 600-750 deg.C (further 650-720 deg.C, for example, about 700 deg.C) by the high temperature gas burned by the burner and fed to the cathode of the solid oxide fuel cell stack where the air electrochemically reacts with the fuel gas of the anode. The volume ratio of air to pre-reformer outlet gas is 7-12:1, further 8-11, further 9-10, e.g. the volume ratio of air to pre-reformer exit gas at 700 ℃ is 9.

(3) The anode tail gas output from the anode of the solid oxide fuel cell stack is at a pressure of about 1-5kPa (further 2-4kPa, e.g. about 3 kPa), at a temperature of 700-800 ℃ (further 730-770 ℃, e.g. about 760 ℃), and the gas is cooled to 450-650 ℃ (further 500-600 ℃, preferably 550 ℃) by a gas heat exchanger and then split into two portions, 20-60% (preferably 25-55 vol%, 30-50 vol%, 35-45 vol% or 40 vol%) of the anode tail gas is mixed with fuel gas via a temperature resistant circulation device, the remaining portion of the anode tail gas is fed to a burner for combustion with a cathode tail gas (typically about 700-850 ℃, further 720-800 ℃, e.g. about 760 ℃, pressure 1-6kPa, e.g. about 3 kPa), the burner outlet temperature is 700-1000 ℃ (further 750-900 ℃, e.g. about 850 ℃), and the combustion tail gas output from the burner is passed through an air preheater for heat transfer to air, the temperature is reduced to 100-200 ℃ (further 120-180 ℃, e.g. about 130-150 ℃, heat is recovered, the temperature is reduced to 40-60 ℃, and then is further discharged via a conduit for evacuation, e.g. 55 ℃, e.g. to a system for heat recovery.

Further, the composition of the biogas in the step (1) is the general composition in the field, and the composition is CH ₄ :50-70%, further 55-67% or 58-65%, e.g. 62%, CO ₂ :30-45%, further 33-40% or 35-39%, e.g. about 37%, N ₂ :0.1-2%, further 0.2-1.5% or 0.3-0.8%, e.g. about 0.5%, CO:0.1-2%, further 0.2-1.5% or 0.3-0.8%, e.g. about 0.4%, other ingredients: 0.01-0.5%, e.g., about 0.1%; units are in mol%.

Further, the pre-reformed gas in the step (1) has the composition of CH ₄ :10.6-25%, further 12-20% or 15-19%, e.g. about 17.37%, H ₂ :12-26%, further 15-22% or 16-19%, e.g. 17.24%, CO ₂ :15-30%, further 18-24% or 19-23%, e.g. about 22.77%, N ₂ :0.15-0.42%, further 0.20-0.35% or 0.21-0.30%, e.g. about 0.21%, CO:0.5-2.3%, further 0.6-2.0 or 0.8-1.5%, e.g. about 1.23%, H ₂ O:30-56%, further 35-48% or 38-43%, for example about 41.18%, in mol%.

Further, the anode tail gas in the step (3) is composed of CH ₄ :3.2-4.5%, further 3.5-4% or 3.6-3.9%, H ₂ :3.0-5.0%, further 3.6-4.2% or 3.8-4.0%、CO ₂ :18-32%, further 20-30% or 22-28%, N ₂ :0.10-0.40%, further 0.15-0.2% or 0.16-0.19%, CO:1.5-5.0%, further 2-3% or 2.2-2.8%, H ₂ O:55-72%, further 60-70% or 62-68%, in mol%;

cathode tail gas composition is O ₂ :10-27%, further 15-22% or 16-20%, e.g. about 18.82%, N ₂ :73-90%, further 75-85% or 78-82%, for example about 81.18%, in mol%.

Further, the composition of the combustion tail gas in the step (3) is CO ₂ :2.0-5.0%, further 2.2-3.5% or 2.5-3%, e.g. about 2.72%, N ₂ :60-82%, further 70-80% or 72-78%, e.g. about 74.75%, H ₂ O:3-10.0%, further 4-6.5% or 4.2-6.2%, e.g. about 6.05%, O ₂ :12-25%, further 15-20% or 16-19%, for example about 16.48%, in mol%.

Further, the reaction temperature of the solid oxide fuel battery pack is 700-800 ℃; the solid oxide fuel cell stack has small pressure bearing capacity, the operating environment is low pressure, and the inlet pressures of cathode gas and anode gas of the solid oxide fuel cell stack are respectively 1-5 kPa; in addition, due to the special design structure and the operation condition of the solid oxide fuel cell, the fuel utilization rate meets 75% -85%, and the utilization rate is too high, so that the anode of the cell is in a high-oxidation environment, and the service life of the anode of the cell is damaged; when the utilization rate is too low, the power generation efficiency is lowered, and the air-fuel ratio is set to 20 to 50 in accordance with the system heat balance.

In this application, "optionally" means with or without subsequent operations.

The utility model has the advantages that:

the device of the utility model is used for enriching CH in the methane ₄ The energy is efficiently, stably and cleanly utilized, the efficient and clean utilization of the energy is realized, and the resources are rationalized. Meanwhile, the whole process flow is simple, the cost of fixed equipment is reduced, the requirement on the pressure resistance of the reactor is reduced under the low-pressure operating condition, and the investment cost is indirectly reduced. The utility model discloses aThe water replenishing is the water recycling generated by the system reaction, and only after the part is added in the initial stage of driving, the internal balance of the system is realized in the later stage. The utility model discloses a radiant heating's method, simple structure, saving space can be better realize thermal recovery.

Drawings

Fig. 1 is a schematic diagram of a device for generating electricity by using biogas in a solid oxide fuel cell according to the present invention.

Fig. 2 is a configuration diagram of a solid oxide fuel cell stack, a combustor, and a pre-reformer, in which fig. 2 (a) is a front view and fig. 2 (b) is a plan view.

Reference numerals:

l1-anode gas conveying pipeline, L2-anode tail gas output pipeline, L3-first branch pipe, L4-second branch pipe, L5-cathode gas conveying pipeline, L6-cathode tail gas output pipeline, L7-combustion tail gas output pipeline, L8-domestic cold water input pipeline and L9-domestic hot water output pipeline.

The system comprises a C101-biogas blower, an R102-desulfurizer, an E102-gas heat exchanger, an R101-prereformer, a C102-air blower, an SOFC-solid oxide fuel cell stack, a C103-temperature-resistant circulating device, an A101-combustor, an E101-air preheater, an E103-tail gas heat recoverer and an A102-steam generator.

Detailed Description

The invention is further described with reference to the following figures and examples.

As shown in fig. 1, the present invention provides a device for generating power by using biogas in a solid oxide fuel cell, which comprises an anode gas conveying pipeline L1 connected to an anode gas inlet of a solid oxide fuel cell stack SOFC, a cathode gas conveying pipeline L5 connected to a cathode gas inlet of the solid oxide fuel cell stack, a biogas blower C101 for pressurizing the anode gas, a desulfurization device R102 for removing sulfur impurities, a pre-reformer R101 for adjusting gas composition, and a gas heat exchanger E102 for heating gas are sequentially arranged on the anode gas conveying pipeline L1 along the anode gas conveying direction, and an air blower C102 for pressurizing the cathode gas, and an air preheater E101 for heating air are sequentially arranged on the cathode gas conveying pipeline L5 along the cathode gas conveying direction.

An anode tail gas output pipeline L2 of the solid oxide fuel cell stack SOFC is divided into a first branch pipe L3 and a second branch pipe L4 after being cooled by a gas heat exchanger, the second branch pipe L4 is connected with a gas inlet of a pre-reformer R101 after passing through a temperature-resistant circulation device C103, the first branch pipe L3 is connected with an anode tail gas inlet of a combustor A101, a cathode tail gas output pipeline L6 of the solid oxide fuel cell stack SOFC is connected with a cathode tail gas inlet of the combustor A101, the volume ratio of the cathode tail gas to the anode tail gas (for example, the cathode tail gas to the anode tail gas is 5-7.

The gas heat exchanger E102 is one of a plate shell type heat exchanger and a plate fin type heat exchanger, an inlet of a low-temperature medium channel of the gas heat exchanger is connected with an anode gas conveying pipeline, and an outlet of a high-temperature medium channel of the gas heat exchanger is connected with a first branch pipe L3 and a second branch pipe L4 through pipelines.

The pre-reformer R101 is a tubular reactor, catalyst is filled in the tubular reactor, an anode gas conveying pipeline is connected with a tube pass inlet, gas after the pre-reformer enters the anode of the solid oxide fuel cell stack SOFC after heat exchange through the gas heat exchanger E102, and the pre-reforming temperature is maintained through radiation transfer of heat generated by the solid oxide fuel cell stack SOFC and the combustor A101.

The air preheater E101 is one of a plate-shell type heat exchanger and a plate-fin type heat exchanger, a combustion tail gas output pipeline L7 of the combustor A101 is connected with a high-temperature medium channel inlet of the air preheater E101, and a cathode gas conveying pipeline L5 is connected with a low-temperature medium channel inlet of the air preheater E101.

The tail gas heat recoverer E103 is one of a plate-shell type heat exchanger and a plate-fin type heat exchanger, a combustion tail gas output pipeline L7 of the combustor is connected with a high-temperature medium inlet of the tail gas heat recoverer E103, a low-temperature medium inlet of the tail gas heat recoverer E103 is connected with a domestic cold water input pipeline L8, a low-temperature medium outlet is connected with a domestic hot water output pipeline L9, and heat of combustion tail gas recovered by the tail gas heat recoverer E103 is used for heating domestic water.

The temperature-resistant circulation device C103 is one of a temperature-resistant circulation blower or a venturi tube for circulating the anode off-gas to the pre-reformer R101.

As shown in fig. 2, the SOFC of solid oxide fuel cell stack, the burner a101 and the pre-reformer R101 are arranged in a ring shape, wherein the pre-reformer R101 is arc-shaped, the burner a101 is located inside the pre-reformer, and the SOFC of solid oxide fuel cell stack is located outside the pre-reformer, i.e. the pre-reformer and part of its inlet pipe (i.e. the pipe section of the anode gas transfer pipe between the outlet of the desulfurizer and the inlet of the pre-reformer near the inlet of the pre-reformer) is located between the solid oxide fuel cell stack and the burner, preferably, the distance between the solid oxide fuel cell stack and the pre-reformer is generally 0.2m to 0.5m, preferably 0.3m to 0.4m, and the distance between the pre-reformer and the burner is generally 0.2m to 0.4m, preferably 0.25m to 0.35m; the distance between the solid oxide fuel cell stack and the burner is 0.4-0.9m, preferably 0.55-0.75m; the outer wall of the pre-reformer and part of its inlet duct is preferably made of a material that absorbs heat well (e.g. a metallic material such as steel or copper) to achieve heat collection and conduction.

An outer casing, preferably made of a heat insulating material, is provided outside the solid oxide fuel cell stack, the pre-reformer and a part of the inlet duct and the burner as a whole, and is preferably in a sealed state for heat preservation and prevention of heat loss to the outside. The reforming temperature and gas temperature can then be adjusted by varying the distance between the components.

Example 1

(1) Biogas (composition: CH) ₄ ：62％、CO ₂ ：37％、N ₂ :0.5%, CO:0.4%, others: 0.1 percent; unit adopts mol percent), after dust removal, the biogas is pressurized by a biogas blower at 6kPa,then enters a desulfurization device along a pipeline, fuel gas (the sulfur content is as low as 0.1 ppm) required by power generation is obtained through normal temperature desulfurization, the fuel gas is preheated to about 300 ℃ along the pipeline, water is supplemented to 2 by a steam generator at the beginning of the reaction, the fuel gas is subsequently mixed with recycle gas (the volume ratio of partial anode tail gas output from the anode of the solid oxide fuel cell stack and the fuel gas output from the desulfurization device to the recycle gas is about 0.64), and then enters a pre-reformer for reforming, the reforming temperature is maintained to be about 450 ℃ through the arrangement of the pre-reformer and a part of inlet pipelines thereof between the solid oxide fuel cell stack and a combustor, the radiant heat generated by the solid oxide fuel cell stack and the combustor, and the reformer is filled with a nickel-based catalyst, the main component of Ni: about 18%, la: about 2%), pre-reformed gas (including CH) ₄ ：17.37％、H ₂ ：17.24％、CO ₂ ：22.77％、N ₂ ：0.21％、CO：1.23％、H ₂ O: 41.18%) was heated to about 700 ℃ using a gas heat exchanger and entered the anode of the solid oxide fuel cell stack;

(2) Pressurizing 6kPa by an air blower, feeding the air into an air preheater, preheating the air to 700 ℃ by high-temperature gas combusted by a combustor, and feeding the air into a cathode of a solid oxide fuel cell stack, wherein the air and fuel gas of an anode generate electrochemical reaction in the solid oxide fuel cell stack, and the volume ratio of the air to the outlet gas of the pre-reformer is about 9;

(3) Anode tail gas (pressure 3kPa, temperature 760 ℃, CH included) output from the anode of the solid oxide fuel cell stack ₄ ：3.72％、H ₂ ：3.98％、CO ₂ ：27.15％、N ₂ ：0.16％、CO：2.15％、H ₂ O: 62.84%) is cooled to 550 ℃ by a gas heat exchanger and then divided into two parts, one part is mixed with fuel gas after passing through temperature-resistant circulating equipment, and the other part of anode tail gas and cathode tail gas (comprising: o is ₂ ：18.82％、N ₂ :81.18 percent, the pressure of cathode tail gas is 3kPa, the temperature is 760 ℃, the cathode tail gas and the tail gas are sent into a combustor to be combusted, the outlet temperature of the combustor is 850 ℃, and the tail gas (comprising CO) of the combustion output from the combustor ₂ ：2.72％、N ₂ ：74.72％、H ₂ O：6.05％、O ₂ : 16.51%) transferred heat to air by an air preheater, the temperature is reduced to 150 ℃, the heat is recovered by a tail gas heat recoverer, and the heat is discharged out of the system by a pipeline after the temperature is reduced to 50 ℃.

The reaction temperature of the solid oxide fuel cell stack is 760 ℃; the inlet pressures of cathode gas and anode gas of the solid oxide fuel cell stack are respectively 4kPa; the solid oxide fuel cell has a fuel utilization of 85% and the air-fuel ratio 40 is designed according to the system heat balance.

Example 2

(1) Biogas (composition: CH) ₄ ：64.5％、CO ₂ ：34.5％、N ₂ :0.43%, CO:0.5%, others: 0.07 percent; unit by mol%) is dedusted, pressurized by a methane blower at 8kPa, enters a desulfurization device along a pipeline, and is desulfurized at normal temperature to obtain fuel gas (the sulfur content is as low as below 0.8 ppm) required by power generation, the fuel gas is preheated to about 320 ℃ along the pipeline by radiation, water is supplemented to 1.5 by a steam generator at the beginning of reaction, and then is mixed with recycle gas (part of anode tail gas output from the anode of the solid oxide fuel cell stack, the volume ratio of the fuel gas from the desulfurization device to the recycle gas is about 0.56 1), and then enters a pre-reformer for reforming, the reforming temperature is maintained at 400 ℃ by the radiation heat generated by the solid oxide fuel cell stack and a combustor, the reformer is filled with a nickel-based catalyst, and the main components are Ni:17%, la: 3%) pre-reformed gas (including CH) by placing the pre-reformer and part of its inlet duct between the solid oxide fuel cell stack and the burner ₄ ：19.4％、H ₂ ：16.71％、CO ₂ ：20.4％、N ₂ ：0.21％、CO：1.20％、H ₂ O: 42.08%) was heated to about 700 c using a gas heat exchanger and fed to the anode of the solid oxide fuel cell stack;

(2) Pressurizing 8kPa by an air blower, feeding the air into an air preheater, preheating the air to 700 ℃ by high-temperature gas combusted by a combustor, and feeding the air into a cathode of the solid oxide fuel cell stack, wherein the air and fuel gas of an anode generate electrochemical reaction in the solid oxide fuel cell stack, and the volume ratio of the air to the outlet gas of the pre-reformer is about 10;

(3) Anode tail gas (pressure 6kPa, temperature 760 ℃, CH included) output from the anode of the solid oxide fuel cell stack ₄ ：3.95％、H ₂ ：4.05％、CO ₂ ：26.03％、N ₂ ：0.52％、CO：2.45％、H ₂ O: 63.0%) is cooled to 570 ℃ by a gas heat exchanger and then divided into two parts, one part is mixed with fuel gas after passing through temperature-resistant circulating equipment, and the other part of anode tail gas and cathode tail gas (comprising: o is ₂ ：15.56％、N ₂ :84.44 percent, the pressure of cathode tail gas is 5kPa, the temperature is 760 ℃, the cathode tail gas is sent into a burner to be burnt, the outlet temperature of the burner is 830 ℃, and the burning tail gas (comprising CO) output from the burner ₂ ：2.62％、N ₂ ：74.83％、H ₂ O：7.05％、O ₂ : 15.50%) transferred heat to air through an air preheater, then the temperature is reduced to 130 ℃, heat is recovered through a tail gas heat recoverer, and the temperature is reduced to 45 ℃ and then is discharged out of the system through a pipeline to be emptied.

The reaction temperature of the solid oxide fuel cell stack is 760 ℃; the inlet pressures of cathode gas and anode gas of the solid oxide fuel cell stack are respectively 6kPa; the fuel utilization of the solid oxide fuel cell stack is 85%, and the air-fuel ratio 35 is designed according to the system heat balance.

The methane SOFC power generation process of the utility model can efficiently, stably and cleanly utilize the methane rich in the methane; the oxidant on the cathode side of the solid oxide fuel cell directly comes from the atmosphere, pretreatment is not needed, and the process is simple; in addition, the recycling of the anode tail gas greatly reduces the water consumption, reasonably utilizes energy and realizes the purpose of energy conservation; meanwhile, the pressure resistance requirement of the equipment is lower, and the cost of the fixed equipment is also reduced. The whole system recycles the heat, and zero loss is basically achieved, so that the overall efficiency of fuel utilization is further improved.

The above description is only a preferred embodiment of the present invention and it is not intended to limit the scope of the present invention, and various modifications and variations of the present invention are possible to those skilled in the art. All the changes, modifications, replacements, integrations and parameter changes of the embodiments which are within the spirit and principle of the invention through the conventional substitution or can realize the same function without departing from the principle and spirit of the invention all fall into the protection scope of the invention.

Claims (10)

1. The device for generating power by utilizing the biogas to the solid oxide fuel cell is characterized by comprising an anode gas conveying pipeline (L1) connected with an anode gas inlet of a solid oxide fuel cell Stack (SOFC), a cathode gas conveying pipeline (L5) connected with a cathode gas inlet of the SOFC, wherein the anode gas conveying pipeline (L1) is sequentially provided with a biogas blower (C101) for pressurizing anode gas, a desulfurization device (R102) for removing sulfur impurities, a pre-reformer (R101) for adjusting gas composition and a gas heat exchanger (E102) for heating gas along the conveying direction of the anode gas, the cathode gas conveying pipeline (L5) is sequentially provided with an air blower (C102) for pressurizing cathode gas and an air preheater (E101) for heating air along the conveying direction of the cathode gas, and a steam feeding pipe is connected with an inlet of the pre-reformer (R101) or a water feeding pipe is connected with an inlet of the pre-reformer (R101) through a steam generator.

2. The device for generating power by utilizing biogas in a solid oxide fuel cell according to claim 1, wherein an anode tail gas output pipeline (L2) of the solid oxide fuel cell Stack (SOFC) is divided into a first branch pipe (L3) and a second branch pipe (L4) after heat exchange by the gas heat exchanger (E102), the first branch pipe (L3) is connected with a gas inlet of the pre-reformer (R101) after passing through the temperature-resistant circulating equipment (C103), the second branch pipe (L4) is connected with an anode tail gas inlet of the combustor (A101), a cathode tail gas output pipeline (L6) of the solid oxide fuel cell Stack (SOFC) is connected with a cathode tail gas inlet of the combustor (A101), the cathode tail gas and the anode tail gas are combusted in the combustor (A101) to generate heat, and a combustion tail gas output pipeline (L7) of the combustor (A101) sequentially passes through the air preheater (E101) and the tail gas heat recoverer (E103) and then is output to the outside the system.

3. The device for generating power by utilizing biogas in a solid oxide fuel cell according to claim 1, wherein the gas heat exchanger (E102) is one of a plate-shell type heat exchanger and a plate-fin type heat exchanger, an inlet of a low-temperature medium channel of the gas heat exchanger (E102) is connected with an anode gas conveying pipeline (L1) out of the pre-reformer (R101), and an outlet of a high-temperature medium channel is connected with the first branch pipe (L3) and the second branch pipe (L4) through pipelines.

4. The apparatus of any of claims 1-3, wherein the pre-reformer (R101) is a tubular reactor, the tubes are filled with catalyst, the anode gas transport line (L1) is connected to the tube side inlet, and the anode gas transport line (L1) is connected to the anode inlet of the solid oxide fuel cell Stack (SOFC) via a gas heat exchanger (E102) after exiting the pre-reformer (R101).

5. The device for generating power by utilizing biogas in a solid oxide fuel cell according to any one of claims 1 to 3, wherein the air preheater (E101) is one of a plate-shell type heat exchanger and a plate-fin type heat exchanger, the combustion tail gas output pipeline (L7) of the burner (A101) is connected with the high-temperature medium channel inlet of the air preheater (E101), and the cathode gas delivery pipeline (L5) after the air blower (C102) is connected with the low-temperature medium channel inlet of the air preheater (E101).

6. The device for generating power by utilizing biogas in a solid oxide fuel cell according to any one of claims 1 to 3, wherein the tail gas heat recovery device (E103) is one of a plate-shell type heat exchanger and a plate-fin type heat exchanger, a combustion tail gas output pipeline (L7) after the tail gas heat recovery device (E101) is connected with a high-temperature medium channel inlet of the tail gas heat recovery device (E103), a low-temperature medium channel inlet of the tail gas heat recovery device (E103) is connected with a domestic cold water input pipeline (L8), and a low-temperature medium channel outlet is connected with a domestic hot water output pipeline (L9).

7. The device for generating power by utilizing biogas in a solid oxide fuel cell according to any one of claims 1 to 3, wherein the temperature-resistant circulation equipment (C103) is one of a temperature-resistant circulation blower or a venturi tube, and the second branch (L4) of the anode tail gas output pipeline (L2) is connected with the inlet of the reformer (R101) after being merged with the anode gas delivery pipeline (L1) after being discharged from the desulfurization device (R102) after being discharged from the temperature-resistant circulation equipment (C103); the first branch pipe (L3) of the anode tail gas output pipeline (L2) is connected with the inlet of the combustor (A101).

8. The apparatus of any one of claims 1 to 3, wherein the solid oxide fuel cell stack, the burner and the pre-reformer are arranged in a ring shape, wherein the pre-reformer is an arc, the burner is located inside the pre-reformer, and the solid oxide fuel cell stack is located outside the pre-reformer, i.e. the pre-reformer and a part of the inlet pipe thereof are located between the solid oxide fuel cell stack and the burner.

9. The apparatus of claim 8, wherein the distance between the solid oxide fuel cell stack and the pre-reformer is 0.2m to 0.5m, and the distance between the pre-reformer and the burner is 0.2m to 0.4m; the distance between the solid oxide fuel cell stack and the burner is 0.4-0.9m.

10. The apparatus of claim 8, wherein a housing made of a heat insulating material is provided outside the solid oxide fuel cell stack, the pre-reformer, a portion of the inlet duct thereof, and the burner.

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