Solid oxide fuel cell power generation system based on oil fuel
阅读说明：本技术 一种基于油类燃料的固体氧化物燃料电池发电系统 (Solid oxide fuel cell power generation system based on oil fuel ) 是由 蒲健 郭群威 杨佳军 贾礼超 颜冬 池波 李箭 于 2019-11-06 设计创作，主要内容包括：本发明属于清洁可再生能源相关技术领域,其公开了一种基于油类燃料的固体氧化物燃料电池发电系统,发电系统包括固体氧化物燃料电池电堆、空气换热器、燃烧室、燃料重整器、水蒸气蒸发器及预混器,空气换热器连接于固体氧化物燃料电池电堆的阴极,燃料重整器连接于固体氧化物燃料电池电堆的阳极,燃烧室连接于固体氧化物燃料电池电堆的尾气出口；燃烧室分别与空气换热器、燃料重整器及预混器相连通；水蒸气蒸发器连接于预混器；固体氧化物燃料电池电堆所产生的尾气进入燃烧室,并在燃烧室内发生催化燃烧以得到热气流,热气流按照预定体积比分别进入空气换热器、燃料重整器及预混器。本发明提高了能量利用效率,同时简化了系统。(The invention belongs to the technical field related to clean renewable energy sources, and discloses a solid oxide fuel cell power generation system based on oil fuel, which comprises a solid oxide fuel cell stack, an air heat exchanger, a combustion chamber, a fuel reformer, a steam evaporator and a premixer, wherein the air heat exchanger is connected to the cathode of the solid oxide fuel cell stack, the fuel reformer is connected to the anode of the solid oxide fuel cell stack, and the combustion chamber is connected to a tail gas outlet of the solid oxide fuel cell stack; the combustion chamber is respectively communicated with the air heat exchanger, the fuel reformer and the premixer; the steam evaporator is connected with the premixer; tail gas generated by the solid oxide fuel cell stack enters a combustion chamber, catalytic combustion is carried out in the combustion chamber to obtain hot air flow, and the hot air flow respectively enters an air heat exchanger, a fuel reformer and a premixer according to a preset volume ratio. The invention improves the energy utilization efficiency and simplifies the system.)
1. A solid oxide fuel cell power generation system based on oil fuel is characterized in that:
the power generation system comprises a solid oxide fuel cell stack, an air heat exchanger (1), a combustion chamber (2), a fuel reformer (3), a steam evaporator (4) and a premixer (5), wherein the air heat exchanger (1) is connected to the cathode of the solid oxide fuel cell stack, the fuel reformer (3) is connected to the anode of the solid oxide fuel cell stack, and the combustion chamber (2) is connected to the tail gas outlet of the solid oxide fuel cell stack; the combustion chamber (2) is respectively communicated with the air heat exchanger (1), the fuel reformer (3) and the premixer (5); the water vapor evaporator (4) is connected to the premixer (5);
tail gas generated by the solid oxide fuel cell stack enters the combustion chamber (2), and is subjected to catalytic combustion in the combustion chamber (2) to obtain hot gas flows, and the hot gas flows respectively enter the air heat exchanger (1), the fuel reformer (3) and the premixer (5) according to a preset volume ratio; the hot air flow entering the air heat exchanger (1) heats the air entering the air heat exchanger (1), and the air heat exchanger (1) transmits the heated air to the cathode of the solid oxide fuel cell stack; the water vapor evaporator (4) is used for converting liquid water into water vapor and transmitting the water vapor to the premixer (5); the steam and hot gas flow entering the premixer (5) heats the atomized fuel entering the premixer (5) to obtain a mixture of fuel gas and steam, the premixer (5) passes the mixture to the fuel reformer (3); the flow direction of the mixed gas entering the fuel reformer (3) is opposite to that of the hot gas flow entering the fuel reformer (3), the fuel reformer (3) carries out step reforming on the mixed gas and transmits the obtained reformed gas to the anode of the solid oxide fuel cell stack, and then the solid oxide fuel cell stack carries out electrochemical power generation.
2. The oil fuel based solid oxide fuel cell power generation system of claim 1, wherein: the temperature of the fuel reformer (3) gradually increases in the flow direction of the mixture; the temperature in the fuel reformer (3) is 450 ℃ to 750 ℃.
3. The oil fuel based solid oxide fuel cell power generation system of claim 1, wherein: the fuel reformer (3) is provided with an accommodating cavity, a corrugated sheet is arranged in the accommodating cavity, the corrugated sheet divides the accommodating cavity into a plurality of layers, the mixed gas and the hot gas flow entering the fuel reformer (3) flow in different layers, and the flow directions of the mixed gas and the hot gas flow are opposite.
4. The oil fuel based solid oxide fuel cell power generation system of claim 3, wherein: and a catalyst is filled between the layers where the mixed gas flows.
5. The oil fuel based solid oxide fuel cell power generation system according to any one of claims 1 to 4, wherein: and a tail gas outlet of the air heat exchanger (1), a tail gas outlet of the fuel reformer (3) and a tail gas outlet of the premixer (5) are communicated, and are respectively provided with a back pressure valve.
6. The oil fuel based solid oxide fuel cell power generation system according to any one of claims 1 to 4, wherein: the premixer (5) is also provided with an atomized fuel inlet (5-1) and a mixed gas outlet (5-2), and the mixed gas outlet (5-2) and a hot air flow inlet of the premixer (5) are respectively positioned at two ends of the premixer (5) which are opposite to each other; the mixed gas outlet (5-2) is communicated with the fuel reformer (3) through a pipeline; the fuel is atomized by the atomizer and then enters the premixer (5) through the atomized fuel inlet (5-1).
7. The oil fuel based solid oxide fuel cell power generation system of claim 6, wherein: the water vapor evaporator (4) is arranged at a hot air flow inlet of the premixer (5) and is wound on a pipeline connected with the hot air flow inlet of the premixer (5); the water vapor evaporator (4) is connected to one end of the premixer (5) and is arranged adjacent to the atomized fuel inlet (5-1).
8. The oil fuel based solid oxide fuel cell power generation system according to any one of claims 1 to 4, wherein: the pipeline through which the mixed gas flows is coated with an insulating layer.
9. The oil fuel based solid oxide fuel cell power generation system according to any one of claims 1 to 4, wherein: the heat generated by the combustion chamber (2) is adjusted by regulating the power generation efficiency of the solid oxide fuel cell stack.
10. The oil fuel based solid oxide fuel cell power generation system according to any one of claims 1 to 4, wherein: the gas outlet pressure is adjusted through the pipe diameter of the hot gas flow pipeline and the backpressure valve so as to regulate and control the gas flow; the diameter of the pipeline connected with the hot gas flow inlet of the fuel reformer (3) is larger than that of the pipeline connected with the hot gas flow inlet of the air heat exchanger (1); the combustion chamber (2) is positioned between the air heat exchanger (1) and the fuel reformer (3), and the premixer (5) and the combustion chamber (2) are respectively positioned at two sides opposite to the fuel reformer (3).
Technical Field
The invention belongs to the technical field related to clean renewable energy sources, and particularly relates to a solid oxide fuel cell power generation system based on oil fuel.
Background
The Solid Oxide Fuel Cell (SOFC) has no combustion process, so that the fuel energy loss and the emission of atmospheric pollutants are greatly reduced, and the SOFC has the advantages that the traditional power generation device does not have, and has wide application prospects in the fields of portable power generation devices, automobile auxiliary power sources, distributed power stations and the like.
The SOFC has higher energy conversion efficiency, can realize more than 50% of electric conversion efficiency, has very high waste heat quality, can be used together with a gas turbine or a steam engine and the like, and ensures that the comprehensive utilization rate of fuel reaches more than 80%. Under the same electric load, the electric efficiency is far higher than that of the traditional heat engine power generation device (less than or equal to 30%). The SOFC has the working temperature of 650-850 ℃, can avoid poisoning of CO on a metal ceramic electrode (Ni-YSZ) and reduce the requirement of the SOFC on the fuel quality, so that the SOFC has strong fuel adaptability and can use hydrogen, hydrocarbon gas, diesel oil, kerosene and the like as fuels. Although SOFCs can theoretically generate electricity directly using hydrocarbons as fuel, for the most commonly used Ni-YSZ anode, the catalytic performance is drastically reduced by carbon deposition and sulfur poisoning occurring on the electrode, and thus hydrocarbon fuels such as methane (CH) are generally used4) Externally reforming methanol and the like to CO and H2And then the fuel is introduced into the anode side of the SOFC pile to generate power. However, the gaseous fuel is inThe storage and transportation and the use have certain limitations, and the volume energy density of the fuel is far smaller than that of oil fuel.
Because the oil fuel contains more long-carbon alkane components, the SOFC anode has strong catalytic activity for C-C bond breakage in the gasified hydrocarbon fuel, and if the cracking and reforming reactions of the long-carbon alkane occur in the anode functional layer, the anode functional layer can generate serious carbon deposition poisoning, so that the anode loses electrochemical catalytic activity. The catalytic reforming of long-chain hydrocarbons to form smaller molecular gas hydrocarbons is more complicated, and therefore is generally accomplished by external reforming, and depending on the reactant gas introduced during reforming, oil-based fuels are mainly reformed in the following three ways: 1. steam Reforming (SR), the reaction of hydrocarbons with steam to form CO and H2(ii) a 2. Partial oxidation reforming (POX), in which hydrocarbons undergo incomplete oxidation with oxygen to form small molecules and water, and the small molecules continue to react with steam to form CO and H2(ii) a 3. Autothermal reforming (ATR), which takes oxygen and steam as reactants, is an integrated reforming mode of SR and POX, and simultaneously takes part in partial oxidation reaction and steam reforming reaction, and the oxidation reaction provides heat for the steam reforming reaction, and the reaction process is as follows:
partial oxidation reforming:
CnHm+aO2→bH2+cCO+dCO2+eH2O(ΔH<0) (1)
steam reforming:
CnHm+aH2O→bH2+cCO+dCO2+eH2O(ΔH>0) (2)
autothermal reforming:
steam reforming has received much attention because it can achieve the maximum hydrogen production rate among the three reforming modes and can effectively suppress the carbon deposition of the catalyst. However, the steam reforming oil fuel plant is generally complicated because the endothermic reaction occurs during steam reforming, catalytic reforming of the oil fuel generally needs to be performed at a high carbon ratio, and the supply of steam also consumes a large amount of heat energy.
Disclosure of Invention
In view of the above drawbacks or needs for improvement in the prior art, the present invention provides a solid oxide fuel cell power generation system based on oil fuel, which is based on the working characteristics of the existing power generation system, and researches and designs a solid oxide fuel cell power generation system based on oil fuel, wherein the power generation system selects a steam reforming mode according to oil fuel such as diesel oil/kerosene, and has the advantages of controllable temperature, good hydrogen selectivity, high yield, etc., but the steam reforming reaction is an endothermic reaction and needs to be performed at a higher temperature, which brings many difficulties to the practical application of steam reforming; based on the integrated design of the oil fuel catalytic reforming device and the SOFC power generation device, the waste heat generated by the SOFC during operation can be used as a heat source for catalytic reforming of the oil fuel and gasification of the oil fuel and water, so that the overall energy utilization efficiency of the fuel cell is improved, and the system is simplified.
In order to achieve the above object, according to one aspect of the present invention, there is provided an oil fuel-based solid oxide fuel cell power generation system, comprising a solid oxide fuel cell stack, an air heat exchanger, a combustor, a fuel reformer, a steam evaporator and a premixer, wherein the air heat exchanger is connected to a cathode of the solid oxide fuel cell stack, the fuel reformer is connected to an anode of the solid oxide fuel cell stack, and the combustor is connected to a tail gas outlet of the solid oxide fuel cell stack; the combustion chamber is respectively communicated with the air heat exchanger, the fuel reformer and the premixer; the water vapor evaporator is connected to the premixer;
tail gas generated by the solid oxide fuel cell stack enters the combustion chamber, and catalytic combustion is carried out in the combustion chamber to obtain hot gas flow, and the hot gas flow respectively enters the air heat exchanger, the fuel reformer and the premixer according to a preset volume ratio; the hot air flow entering the air heat exchanger heats the air entering the air heat exchanger, and the air heat exchanger transmits the heated air to the cathode of the solid oxide fuel cell stack; the water vapor evaporator is used for converting liquid water into water vapor and transmitting the water vapor to the premixer; the steam and hot gas flow entering the premixer heats the atomized fuel entering the premixer to obtain a mixture of fuel gas and steam, the premixer passes the mixture to the fuel reformer; the flow direction of the mixed gas entering the fuel reformer is opposite to that of the hot gas flow entering the fuel reformer, the fuel reformer carries out step reforming on the mixed gas, the obtained reformed gas is transmitted to the anode of the solid oxide fuel cell stack, and then the solid oxide fuel cell stack carries out electrochemical power generation.
Further, the temperature of the fuel reformer gradually increases in the flow direction of the mixture gas; the temperature in the fuel reformer is 450 ℃ to 750 ℃.
Furthermore, the fuel reformer is provided with an accommodating cavity, a corrugated sheet is arranged in the accommodating cavity, the corrugated sheet divides the accommodating cavity into a plurality of layers, and the mixed gas and the hot air flow entering the fuel reformer flow between different layers in opposite flowing directions.
Further, a catalyst is filled between layers where the mixture flows.
Further, a tail gas outlet of the air heat exchanger, a tail gas outlet of the fuel reformer and a tail gas outlet of the premixer are communicated, and are respectively provided with a back pressure valve.
Furthermore, the premixer is also provided with an atomized fuel inlet and a mixed gas outlet, and the mixed gas outlet and the hot gas inlet of the premixer are respectively positioned at two ends of the premixer, which are opposite to each other; the mixed gas outlet is communicated with the fuel reformer through a pipeline; the fuel is atomized by the atomizer and then enters the premixer through the atomized fuel inlet.
Further, the water vapor evaporator is arranged at a hot air flow inlet of the premixer and is wound on a pipeline connected with the hot air flow inlet of the premixer; the water vapor evaporator is connected to one end of the premixer and is arranged adjacent to the atomized fuel inlet.
Furthermore, the pipeline through which the mixed gas flows is coated with an insulating layer.
Further, the heat generated by the combustion chamber is adjusted by regulating the power generation efficiency of the solid oxide fuel cell stack.
Further, the diameter of the duct to which the hot gas flow inlet of the fuel reformer is connected is larger than the diameter of the duct to which the hot gas flow inlet of the air heat exchanger is connected; the combustion chamber is positioned between the air heat exchanger and the fuel reformer, and the premixer and the combustion chamber are respectively positioned at two sides opposite to the fuel reformer.
In general, compared with the prior art, the solid oxide fuel cell power generation system based on oil fuel provided by the invention mainly has the following beneficial effects:
1. and tail gas generated by the solid oxide fuel cell stack enters the combustion chamber, and is subjected to catalytic combustion in the combustion chamber to obtain hot gas flow, the hot gas flow respectively enters the air heat exchanger, the fuel reformer and the premixer according to a preset volume ratio, and waste heat generated during the operation of the SOFC and heat released by combustion of thin combustible gas in the catalytic tail gas are used as heat sources for catalytic reforming of oil fuel and gasification of the oil fuel and water, so that the overall energy utilization efficiency of the fuel cell is improved, the system is simplified, and the carbon deposition behavior of a catalyst of the hydrocarbon fuel in the reforming process is effectively avoided.
2. The combustion chamber is used as a part for concentrating the waste heat of the SOFC, and a catalytic combustion mode is adopted to adapt to the combustion of lean fuel, so that the heat supply of a liquid fuel reforming system is regulated and controlled, and the operation is simple.
3. The mixed gas entering the fuel reformer and the hot gas flow entering the fuel reformer have opposite flow directions to form a temperature gradient, so that reforming catalysts aiming at different fuels and catalytic temperatures can be placed in different temperature sections of the reformer, the flexibility is good, and the applicability is strong.
4. The water evaporation is carried out at the hot air flow inlet, so that the temperature of the hot air flow can be reduced to a certain degree, and the high-temperature cracking of fuel gas and the generation of carbon deposition caused by overhigh temperature in the premixer are avoided; the atomized oil fuel is introduced, the atomized fuel is mixed with high-temperature steam, and the mixture is gasified under the combined action of the high-temperature steam and hot air, so that the steam and the fuel can be mixed more uniformly, meanwhile, the existence of the steam also avoids the high-temperature cracking and carbon deposition of the fuel to a certain extent, and the mixed gas is introduced into the fuel reformer to carry out reforming reaction.
5. For the regulation and control of the overall heat, the SOFC electric pile power generation efficiency is reduced or increased, so that the content of the thin combustible gas in the tail gas is increased or reduced to increase or reduce the heat generated in the combustion chamber, and the optimal balance between the SOFC power generation efficiency and the reforming efficiency of the fuel reformer is realized.
6. The pipelines through which the hot gas flows are all provided with heat insulating layers so as to avoid fuel condensation and liquefaction before the gaseous fuel is introduced into the fuel reformer.
Drawings
FIG. 1 is a partial schematic view of an oil fuel based solid oxide fuel cell power generation system provided by the present invention;
FIG. 2 is a partial schematic view of a fuel reformer of the oil fuel based solid oxide fuel cell power generation system of FIG. 1;
FIG. 3 is a cross-sectional view of the fuel reformer of FIG. 2;
fig. 4 is a sectional view of the fuel reformer taken along a-a direction in fig. 2.
The same reference numbers will be used throughout the drawings to refer to the same or like elements or structures, wherein: the device comprises a 1-air heat exchanger, a 1-1-high temperature air outlet, a 1-2-low temperature air inlet, a 2-combustion chamber, a 2-1-low temperature tail gas outlet, a 2-2-SOFC high temperature tail gas inlet, a 3-fuel reformer, a 3-1-high temperature reformed gas outlet, a 3-2-mixed gas inlet, a 4-steam evaporator, a 4-1-liquid water inlet, a 5-premixer, a 5-1-atomized fuel inlet, a 5-2-mixed gas outlet, a 6-mixed gas, a 7-hot air flow, an 8-catalyst, a-a first temperature measuring point, a b-a second temperature measuring point and a c-a third temperature measuring point.
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is described in further detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention. In addition, the technical features involved in the embodiments of the present invention described below may be combined with each other as long as they do not conflict with each other.
Referring to fig. 1, in the solid oxide fuel cell power generation system based on oil fuel provided by the present invention, part of heat generated by the SOFC stack during operation is distributed to the air heat exchanger, the fuel reformer and the premixer according to a certain proportion, and is distributed according to a certain proportion, and part of heat can convert the oil fuel into gaseous fuel and is premixed with water vapor; another part of the heat entering the fuel reformer will make the fuel reformer form a temperature gradient of 450 ℃ to 750 ℃ at the positions of the fuel inlet and the fuel outlet, and the arrangement of the reforming catalyst can be carried out according to different fuels and catalytic temperatures; progressive conversion of premixed oil fuel and steam to CO and H as they pass through a fuel reformer2The arrangement can fully utilize the heat of the SOFC to gasify the oil fuel and ensure the steam reforming reaction to be smoothly carried out; the temperature gradient formed by the integrated design of the fuel reformer can effectively avoid the carbon deposition behavior of the catalyst in the reforming process of the hydrocarbon fuel, thereby improving the overall fuel utilization rate and electrical efficiency of the SOFC based on the oil fuel.
The solid oxide fuel cell power generation system comprises a solid oxide fuel cell stack, a plurality of back pressure valves, an air heat exchanger 1, a combustion chamber 2, a fuel reformer 3, a steam evaporator 4 and a premixer 5, wherein one end of the combustion chamber 2 is respectively communicated with the air heat exchanger 1, the fuel reformer 3 and the premixer 5, and the steam evaporator 4 is arranged on a pipeline connected to the premixer 5 and is communicated with the premixer 5. The fuel reformer 3 is in communication with the premixer 5.
The air heat exchanger 1 is provided with a high-temperature air outlet 1-1 and a low-temperature air inlet 1-2, the high-temperature air outlet 1-1 is connected to the cathode of the solid oxide fuel cell stack, and the low-temperature air inlet 1-2 is used for allowing low-temperature air to pass through so as to enter the air heat exchanger 1. The back pressure valve is arranged at a tail gas outlet of the air heat exchanger 1, and a pipeline where the back pressure valve is located is communicated with a low-temperature tail gas outlet 2-1 arranged on the combustion chamber 2. The air heat exchanger 1 is also connected to the combustion chamber 2 by a pipe.
The combustor 2 is provided with a low-temperature tail gas outlet 2-1 and a SOFC high-temperature tail gas inlet 2-2, and the low-temperature tail gas outlet 2-1 is respectively communicated with the tail gas outlet of the air heat exchanger 1, the tail gas outlet of the fuel reformer 3 and the tail gas outlet of the premixer 5. The SOFC high-temperature tail gas inlet 2-2 is communicated with a tail gas outlet of the solid oxide fuel cell stack, so that the high-temperature tail gas of the solid oxide fuel cell stack enters the combustion chamber 2, and then catalytic combustion is carried out in the combustion chamber 2 to generate hot gas flow. In the present embodiment, the combustion chamber 2 adopts a catalytic combustion mode to adapt to the combustion of lean fuel, thereby regulating and controlling the heat supply of liquid fuel.
The hot gas flow outlet of the combustion chamber 2 is respectively communicated with the hot gas flow inlet of the air heat exchanger 1, the hot gas flow inlet of the fuel reformer 3 and the hot gas flow inlet of the premixer 5, so that the hot gas flows proportionally enter the air heat exchanger 1, the fuel reformer 3 and the premixer 5 respectively. Wherein, the hot air flow entering the air heat exchanger 1 heats the air, and the heated air enters the cathode of the solid oxide fuel cell stack.
Referring to fig. 2, 3 and 4, the fuel reformer 3 is provided with a high temperature reformed gas outlet 3-1 and a mixed gas inlet 3-2, the high temperature reformed gas outlet 3-1 is connected to the anode of the solid oxide fuel cell stack, and the mixed gas inlet 3-2 is connected to the mixed gas outlet 5-2 of the premixer 5. And a tail gas outlet of the fuel reformer 3 is provided with a back pressure valve, and a pipeline where the back pressure valve is arranged is communicated with the low-temperature tail gas outlet 2-1.
The fuel reformer 3 is internally provided with a layered structure, specifically, the reformer 3 is provided with an accommodating cavity, the accommodating cavity is internally provided with a corrugated sheet, the corrugated sheet divides the accommodating cavity into a plurality of layers, the mixed gas entering the fuel reformer 3 and hot air flow in different layers flow in opposite directions, and the mixed gas is reformed from a low-temperature region to a high-temperature region. In addition, the corrugated sheet also serves to increase the relative resistance of the contact area to the flow of gas, so that heat transfer is more effectively achieved. And a
In the present embodiment, the fuel reformer 3 utilizes the reverse flow of the hot gas flow and the mixed gas to realize that the temperature of the hot gas flow is distributed in a gradient manner in the flowing direction of the mixed gas, and the mixed gas realizes the distributed catalytic reforming reaction in different temperature intervals; different types and quantities of reforming catalysts can be filled according to the difference of gas components in different temperature sections, so that the efficiency and the selectivity of reforming catalysis are improved, and the consumption of noble metal catalysts is reduced.
The fuel reformer 3 is provided with a first temperature measuring point a, a second temperature measuring point b and a third temperature measuring point c at intervals along the flowing direction of the mixed gas, when the mixed gas is between the first temperature measuring point a and the second temperature measuring point b, most of fuel is converted, because the section from the first temperature measuring point a to the second temperature measuring point b is a main heat absorption section of the fuel reformer 3, the temperature is low and is about 500 ℃,the products are C1-C3 hydrocarbon, CO and H2Hydrocarbon with CH4Mainly small amount of C2 and C3 hydrocarbon, and very small amount of long-chain hydrocarbon which is not catalytically converted and products formed after the long-chain hydrocarbon is cracked, aromatic hydrocarbon and the like. The mixed gas between the second temperature measuring point b and the third temperature measuring point c basically realizes full catalytic conversion, the temperature is high, and at about 700 ℃, the product only contains CO and CO2And H2And unreacted water vapor.
In the present embodiment, the fuel reformer 3 preheats the mixture gas at the mixture gas inlet 3-2, and the mixture gas is preheated to about 450 ℃ before entering the fuel reformer 3; the temperature of the fuel reformer 3 is increased from the mixed gas inlet 3-2 to the hot gas inlet of the fuel reformer 3 due to the directional flow heating of hot gas flow, the mixed gas is gradually reformed and catalytically converted in different temperature intervals, and is completely converted into CO and H at the high-temperature reforming gas outlet 3-12And the electrochemical power generation can be carried out by directly entering the anode of the solid oxide fuel cell stack.
And a tail gas outlet of the premixer 5 is provided with a back pressure valve, and a pipeline where the back pressure valve is located is communicated with the low-temperature tail gas outlet 2-1. The premixer 5 is also provided with an atomized fuel inlet 5-1 and a mixed gas outlet 5-2, and the mixed gas outlet 5-2 and the hot air inlet of the premixer 5 are respectively positioned at two ends of the premixer 5 opposite to each other. The mixed gas outlet 5-2 is communicated with the mixed gas inlet 3-2. The fuel is atomized by the atomizer and then enters the premixer 5 through the atomized fuel inlet 5-1. In the present embodiment, the fuel is diesel oil, kerosene, or gasoline.
The steam evaporator 4 is wound on a pipeline connected with a hot gas inlet of the premixer 5 and communicated with the premixer 5, and liquid water enters the steam evaporator 4 and is heated by the temperature outside the pipeline to form steam. The water vapor evaporator 4 is provided with a liquid water inlet 4-1, and liquid water enters the water vapor evaporator 4 through the liquid water inlet 4-1. In the present embodiment, the ends of the steam evaporator 4 connected to the premixer 5 are disposed adjacent to the atomized fuel inlet 5-1 and are all located at one end of the premixer 5.
The atomized fuel entering the premixer 5 is gasified in the premixer 5, and is mixed with steam in a gaseous state, the gas is heated to a certain temperature by
In the embodiment, based on the calculation of gas pressure, vent pipes with different diameters and a back pressure valve are selected to controllably regulate gas flux, the SOFC waste heat is proportionally distributed, part of heat is provided for a fuel reformer, and the temperature of reformed CO and H2 gas reaches the SOFC reactor reaction temperature (above 650 ℃); part of heat is provided for oil fuel to be evaporated, and simultaneously, liquid water completes the gasification process through a metal coil arranged in a high-temperature pipeline and is uniformly mixed with the gasified fuel in a premixer 5; the pipelines are all provided with heat insulation layers to avoid the condensation and liquefaction of the gaseous fuel before the gaseous fuel is introduced into the fuel reformer 3.
During operation, at the start-up stage of the SOFC stack, hydrogen is introduced into the solid oxide fuel cell stack through an external pipeline, tail gas of the solid oxide fuel cell stack enters the combustion chamber 2, and catalytic combustion is performed in the combustion chamber 2, so as to generate heat, and the generated hot gas flows respectively enter the air heat exchanger 1, the fuel reformer 3 and the premixer 5. The hot air flow entering the air heat exchanger 1 heats the air, and the heated air is transmitted to the cathode side of the solid oxide fuel cell stack, so that the oxygen in the air is subjected to a reduction reaction to form oxygen ions; the hot gas flow entering the fuel reformer 3 heats the mixed gas and transmits the generated high-temperature reformed gas to the anode of the solid oxide fuel cell stack, so that the high-temperature reformed gas (mainly comprising hydrogen and carbon monoxide) is subjected to oxidation reaction to form water and carbon dioxide, and electric energy and heat energy are generated.
A large amount of the solid oxide fuel cell stack is generated as the electrochemical reaction proceedsThe heat of reaction, in addition to maintaining the heat required by the solid oxide fuel cell stack itself, can also be used to preheat air and mixture through the air heat exchanger 1. When the solid oxide fuel cell stack is in the working temperature state, the fuel can be discharged from the H2And switching to oil fuel to carry out electrochemical power generation. In addition, since the fuel introduced into the solid oxide fuel cell stack cannot be fully utilized, the tail gas at the outlet of the solid oxide fuel cell stack contains thin combustible gas, the combustion chamber 2 can perform catalytic combustion by using the thin combustible gas, and the generated heat can increase the temperature of air and a mixed gas.
In the air heat exchanger 1 section, the hot air flow generated in the combustion chamber 2 flows in the reverse direction to the cold air, thereby heating the air. In the premixer 5 section, steam may be mixed with the gasified oil-based fuel. Wherein, the pipeline for water is wound at the inlet of the hot air flow pipeline of the premixer 5, high-temperature steam can be formed by the heat of the pipeline, and then the high-temperature steam is introduced into the premixer 5. The water evaporation at the hot air flow inlet can reduce the temperature of the hot air flow to a certain extent, and avoids the high temperature cracking of the fuel gas and the carbon deposition caused by the overhigh temperature in the premixer 5. The atomized oil fuel is introduced, the atomized fuel is mixed with high-temperature steam, and the atomized fuel is gasified under the combined action of the high-temperature steam and hot air, so that the steam and the fuel can be mixed more uniformly, meanwhile, the existence of the steam also avoids the high-temperature cracking and carbon deposition of the fuel to a certain extent, and the mixed gas is introduced into the fuel reformer 3 for reforming reaction.
Since the heat required for operation of the air heat exchanger 1, the fuel reformer 3 and the premixer 5 differs, there are three regulation schemes: (1) the vent pipes with different inner diameters are used at hot air flow inlets of all the parts, so that the parts with more heat requirements can obtain larger gas flow, and the method belongs to rough adjustment; (2) a back pressure valve is arranged at the hot air flow outlet of each part, and the back pressure valve is used for further accurately controlling the air flow; (3) for the regulation of the overall heat, the SOFC stack power generation efficiency is reduced or increased, so that the content of the lean combustible gas in the tail gas is increased or reduced to increase or reduce the heat generated in the combustion chamber 2, thereby achieving the optimal balance between the SOFC power generation efficiency and the reforming efficiency of the fuel reformer 3.
The fuel reformer 3, which is a part where reforming reaction occurs, has the largest heat demand, and thus is closest to the combustion chamber 2, and has the largest pipe diameter at the hot gas flow inlet; secondly, the air heat exchanger 1 needs to heat air to about the SOFC working temperature range (700 ℃), and finally the premixer 5 has a large demand on heat, but has a low demand on the temperature of hot air flow, and only the steam needs to be heated to about 400 ℃ finally, so the pipe diameters of hot air flow inlets of the premixer 5 and the air heat exchanger 2 are approximately equal, but the distribution positions are different;
when the fuel reformer 3 needs a large amount of heat during adjustment, the pressure at the position of the back pressure valve can be reduced by adjusting the back pressure valve, so that the pressure difference between the tail gas outlet of the fuel reformer 3 and the hot gas inlet of the fuel reformer is increased, and the gas flow is increased. When the integral heat demand is larger, the generating efficiency can be reduced by regulating and controlling the gas supply proportion (air and fuel) of the solid oxide fuel cell stack, so that the combustible gas component in the tail gas of the fuel cell is increased, and more heat is provided by catalytic combustion of the combustion chamber 2.
It will be understood by those skilled in the art that the foregoing is only a preferred embodiment of the present invention, and is not intended to limit the invention, and that any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the scope of the present invention.
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