KR100987823B1 - Solid Oxide Fuel Cell System - Google Patents

Abstract

The present invention relates to a solid oxide fuel cell system, and more particularly, a reformer receiving a liquid hydrocarbon-based raw material to generate a hydrogen-rich reformed gas; A heater attached to the reformer outer wall to warm the reformer to an initial ignition temperature; A desulfurizer which receives fuel gas discharged from the reformer and removes sulfur to generate fuel gas; A complex heat exchanger for raising a temperature of air and fuel gas discharged from the desulfurizer; A solid oxide fuel cell stack configured to generate electricity by receiving the fuel gas heated in the complex heat exchanger through a cathode gas inlet and receiving the air heated in the complex heat exchanger through a cathode gas inlet; And a catalytic combustor configured to generate a combustion gas by receiving the cathode and the discharge gas of the anode discharged from the solid oxide fuel cell stack, wherein the complex heat exchanger exchanges heat between the combustion gas, the fuel gas, and air. The solid oxide fuel cell stack, the reformer, the heater, the desulfurizer, the catalytic combustor, and the composite heat exchanger are related to a solid oxide fuel cell system provided in one hot box.

Solid Oxide Fuel Cell Systems, Reformers, Catalytic Combustors, Heat Exchangers, Hot Boxes

Description

Solid Oxide Fuel Cell System

The present invention relates to a solid oxide fuel cell system including a reformer, a heat exchanger, a catalytic combustion unit, and a solid oxide fuel cell stack. In detail, the system can be miniaturized and lightened, and a solid oxide fuel cell system can be provided with minimal heat supply. The present invention relates to a solid oxide fuel cell system capable of initial driving and capable of thermally independent operation.

The demand for energy is increasing worldwide due to industrial development and population growth, but the production of oil and natural gas, the main energy sources, is expected to decrease gradually from about 2020. With the depletion of fossil fuels, there is an urgent need for research and development on alternative clean energy sources that do not pollute the environment.

In 1997, the Kyoto Protocol was adopted to reduce greenhouse gas emissions, and ratified by 119 countries including Korea, and mandatory reduction of greenhouse gas emissions and the burden of mandatory greenhouse gas reduction are underway.

The technology that uses various natural resources such as solar heat, wind power and hydrogen energy as the energy source is being researched and developed. However, unlike conventional thermal power generation, 1) thermodynamic limitation is limited by direct power generation without the combustion process or mechanical work. ) High power generation efficiency of 40 ~ 60%, almost constant efficiency even in wide load range of 25 ~ 100% of rated power, 2) Nitrogen compounds (NOx), sulfur compounds (SOx), etc. CO ₂ emissions can be reduced by more than 30%, and operating noise / vibration is also a very eco-friendly energy technology. 3) It is possible to produce electricity directly at home or industrial sites by using a distributed power generation method. 4) It is a system that can be supplied and does not require transmission / distribution. 4) Medium and large power generation system in the scale of 100㎾ ~ 10㎿, small household power generation system of 1㎾ ~ 10㎾ It spotlighted as; (solid oxide fuel cell SOFC) the alternative clean energy technology auxiliary power source for cars, can be by W~ ㎾ class lighting movable power source, such as power capacity easily adjust the size of the solid oxide fuel cell.

A solid oxide fuel cell is an energy conversion device that converts chemical energy owned by a fuel gas directly into electrical energy by an electrochemical reaction. In the electrochemical reaction of a solid oxide fuel cell, in the anode, hydrogen meets oxygen ions that have passed through electrons and moves through the electrolyte to generate water and heat, and the electrons generated at the anode produce a DC current through an external circuit. It moves to the cathode, meets oxygen at the cathode, becomes oxygen ions, and the generated ions move to the anode through the electrolyte.

The potential difference obtained from one basic unit cell of a fuel cell of an anode / electrolyte / air electrode is about 1 V. Therefore, in order to use the fuel cell as a power source, the fuel cell is mainly focused on a stack in which several unit cells are connected in series and in parallel. The system is being configured.

Typical fuel cell systems include SOFC stacks that produce electricity, fuel processors that supply hydrogen / hydrocarbon and oxygen to the stacks, conversion systems that convert DC power produced by SOFC stacks to AC power, and SOFCs And a heat recovery device for recovering heat.

The fuel cell may be an alkaline fuel cell (AFC), a phosphoric acid fuel cell (PAFC), a polymer electrolyte fuel cell (PEMFC), a molten carbonate fuel cell (MCFC), or a solid oxide fuel cell (SOFC), depending on the material of the electrolyte used. In the case of the polymer electrolyte fuel cell (PEMFC), the most demanding fuel treatment is required, and in the case of the solid oxide fuel cell (SOFC), it is known that sufficient fuel treatment is possible only by internal reforming in the stack.

Specifically, in the case of the polymer electrolyte fuel cell (PEMFC), after the desulfurization treatment to remove the sulfur component from the natural gas, a reforming process for generating hydrogen is performed, the removal of CO generated during the reforming reaction (water shift reaction) ) And a selective oxidation reaction is further carried out. The concentration of CO should be controlled to 100 ppm or less through the CO removal step. However, in the case of a solid oxide fuel cell (SOFC), since CO itself can be used as a fuel, catalyst materials provided in the solid oxide fuel cell stack after desulfurization are used. Fuel treatment can be achieved only by internal reforming.

Table 1 below summarizes the usable fuels, conductive ionic materials, fuel reforming methods, and technical problems to be solved for each fuel cell type.

(Table 1)

Fuel cell MCFC SOFC PAFC PEMFC DMFC Working temperature (℃) 550-700 600-1000 150-250 50-100 50-100 ion CO ₃ ^2- O ^2- H ⁺ H ⁺ H ⁺ Possible fuel H ₂ , CO H ₂ , CO, methane H ₂ , methanol H ₂ Methanol External reformer Unnecessary Unnecessary need need need problem Corrosion, volatilization High temperature deterioration,
stability corrosion,
Phosphate Outflow High Cost,
Low efficiency High Cost,
Methanol crossover

Fuel reforming in a fuel cell means converting the fuel provided as a raw material into the fuel required in the fuel cell stack.

In the case of PAFC, PEMFC, and DMFC, which are low temperature fuel cells using platinum catalysts, as shown in Table 1, it is necessary to reduce and suppress the CO concentration in the reforming gas by using an external reformer to prevent catalyst deterioration. In high-temperature fuel cells such as MCFC and SOFC, which are used as catalysts, CO can be used as a fuel, eliminating the need for a CO removal process, and can cause reforming reactions at the anode containing nickel in the stack (internal reforming). Is known to be unnecessary.

Specifically, the reforming of hydrocarbon fuels is conventionally steam reforming using a nickel catalyst. That is, it is a reforming reaction in which CO and H ₂ are generated by reacting a hydrocarbon gas with water vapor under a nickel catalyst. Since the reforming reaction is an endothermic reaction, heat supply from the outside is required.

In addition to this steam reforming, an automatic thermal reforming combining partial oxidation reforming, which reacts hydrocarbon fuel with oxygen to produce CO and H ₂ , and steam reforming and partial oxidation reforming can be used.

Then, in the case of a low temperature fuel cell using a platinum-based catalyst as an electrode catalyst, a shift reaction is performed in which water vapor is reacted with CO again to oxidize to CO ₂ .

Then, if necessary, in order to reduce the CO concentration to 10 ppm or less, a selective oxidation reaction for selectively oxidizing CO in an atmosphere having a high hydrogen concentration is performed.

As described above, since SOFC and MCFC are fuel cells that use nickel-based anodes and operate at high temperatures, carbon monoxide can be used as a fuel and hydrocarbons by internal reforming at the anode can be used. It is common for fuel reformers for SOFCs to be composed of only a desulfurizer and a pre-reformer for removing sulfur.

In this case, when a liquid hydrocarbon system is used as the fuel, sufficient reforming efficiency cannot be obtained by only such a pre-reformer and internal reforming in the stack, so that a desulfurizer and a reformer constitute a fuel reformer for SOFC, but it is operated at high temperature. Due to the nature of SOFCs, carbon monoxide and methane contained in hydrogen can also be used as fuels, so the reforming requirements are not strict.

In a conventional SOFC system having an external reformer, Japanese Laid-Open Patent Publication No. 2006-351293 discloses a desulfurizer for desulfurizing liquid fuel, a vaporizer for making reformed fuel from liquid fuel and water, and hydrogen rich (H ₂ -rich) from the reformed fuel. An SOFC system has been proposed that includes a reformer and a solid electrolyte SOFC cell to produce a gas.

Japanese Laid-Open Patent Publication No. 2006-351292 discloses a SOFC system including a desulfurization apparatus for desulfurizing hydrocarbon raw materials, a reformer for making a desulfurized hydrocarbon raw material into a hydrogen-rich (H ₂ -rich) gas, and a solid electrolyte SOFC cell. A system has been proposed that includes a desulfurizer in which the apparatus removes sulfur compounds, a desulfurization feed tank for storing desulfurized hydrocarbon feedstock and a return flow path from the desulfurization feedstock tank to the desulfurizer.

US Patent Publication No. 2007-0092766 relates to a fuel processing apparatus, comprising a liquid desulfurizer for partially desulfurizing a liquid raw material, a fuel transfer device for vaporizing / transferring a liquid raw material partially desulfurized by a liquid desulfurizer, and desulfurizing a vaporized raw material. A fuel treatment apparatus has been proposed that includes a gaseous desulfurizer and a reformer made of hydrogen rich (H ₂ -rich) gas.

Among the above-described internal reforming methods and external reforming methods through an external reformer, when the internal reforming method is used, it is not necessary to configure a separate reformer and is excellent in terms of efficiency of the system because it uses heat generated in the stack. However, internal reforming has many difficulties in terms of system stability for applications with portable social fuels such as diesel with sufficient social infrastructure and high hydrogen density. Therefore, it is inevitable to employ an external reforming method for diesel which has been proven to be excellent in various aspects.

For the stable operation of the SOFC system, it is very important to keep the fuel reformer and fuel cell at a high operating temperature, which requires proper component placement inside the system. In addition, in order to increase the overall efficiency of the fuel cell system, a thermal independent operation is possible, and a system for minimizing external energy required for initial operation is required.

However, in the design of a fuel cell system including a conventional fuel reformer, various methods for increasing the efficiency of individual components have been studied and proposed, but none has been studied in relation to the overall arrangement of the system detailed components. .

In addition, it is common to heat each component to a substantial operating temperature using enormous external energy, such as joule heat, for the initial operation of the SOFC system, and unreacted fuel inside the SOFC stack is usually discharged out and discarded. This reduces the overall system efficiency.

An object of the present invention for solving the above problems is the initial drive with a minimum amount of heat, and after the initial drive, the thermal independent operation and the temperature control of the entire system and each component is possible, the heat availability of the system itself is very It is possible to provide a solid oxide fuel cell system that is high in size, light in size, and light in system construction cost.

The solid oxide fuel cell system according to the present invention comprises a reformer for receiving a hydrocarbon-based raw material of the liquid phase to produce a hydrogen-rich reformed gas; A heater attached to the reformer outer wall to warm the reformer to an initial ignition temperature; A desulfurizer which receives fuel gas discharged from the reformer and removes sulfur to generate fuel gas; A complex heat exchanger for raising a temperature of air and fuel gas discharged from the desulfurizer; A solid oxide fuel cell stack configured to generate electricity by supplying fuel gas heated in the complex heat exchanger to a cathode gas inlet and receiving air heated in the complex heat exchanger into a cathode gas inlet; And a catalytic combustor configured to generate combustion gas by receiving and combusting the exhaust gas of the cathode and the anode discharged from the solid oxide fuel cell stack; The composite heat exchanger is configured to include heat exchange between the combustion gas and the fuel gas and air, and the solid oxide fuel cell stack, the reformer, the heater, the desulfurizer, the catalytic combustion unit, and the composite heat exchanger are one There is a feature provided in a hot box.

Solid oxide fuel cell system according to the present invention comprises a raw material supply pump for supplying the hydrocarbon-based raw material to the reformer; A water supply pump for supplying water to the reformer; A mass flow controller (MFC) for supplying air to control a flow rate of air supplied to the reformer; And a cathode MFC for controlling a flow rate of air supplied to the cathode gas inlet of the solid oxide fuel cell stack, wherein the reformer is heated to an ignition temperature by the heater, and then the raw material supply pump and The raw material and the air are supplied to the reformer under the condition of complete oxidation by the air supply MFC, and the raw material and the air are heated to the operating temperature of the reformer by non-ignition spontaneous ignition of the supplied raw material.

After the reformer is heated to an operating temperature, the fuel cell stack is heated, wherein the solid oxide fuel cell stack is heated to a reaction temperature by hot fuel gas and air discharged from the complex heat exchanger. .

The solid oxide fuel cell system according to the present invention further includes a first vent valve in front of the anode gas inlet of the fuel cell stack and is supplied to the solid oxide fuel cell stack by the first vent valve. The flow rate of fuel gas is controlled.

In the solid oxide fuel cell system according to the present invention, a second vent valve is further provided at a rear end of the anode gas outlet of the solid oxide fuel cell stack, and the solid oxide is supplied to the catalytic combustor by the second vent valve. The flow rate of the exhaust gas discharged from the fuel electrode of the fuel cell stack is controlled.

The reformer further comprises a spray nozzle, characterized in that the raw material and air through the spray nozzle is mixed and sprayed into the reformer, the water supplied to the reformer is one end is connected to the water supply pump and the other An end is supplied through a water supply pipe connected to the reformer, and the water is introduced into the reformer into water vapor by heat exchange at a contact surface between the water supply pipe and the outer wall of the reformer.

The combustion gas discharged from the complex heat exchanger is heat-exchanged with the reformer, the desulfurizer, the catalytic combustor, the hot box, or a combination thereof through an exhaust pipe through which the combustion gas is exhausted.

A temperature of each of the reformer, the desulfurizer, the catalytic combustor, and the solid oxide fuel cell stack may control the flow rate of the raw material supplied to the reformer; An MFC for controlling the flow rate of air supplied to the cathode gas inlet of the solid oxide fuel cell stack; And a first vent valve for controlling the flow rate of the fuel gas supplied to the solid oxide fuel cell stack and a second vent valve for controlling the flow rate of the anode exhaust gas supplied to the catalytic combustor.

Thereby, the raw material supply pump for controlling the flow rate of the raw material is also supplied to the reformer temperature of the hot box; An MFC for controlling the flow rate of air supplied to the cathode gas inlet of the solid oxide fuel cell stack; And a first vent valve for controlling the flow rate of the fuel gas supplied to the solid oxide fuel cell stack and a second vent valve for controlling the flow rate of the anode exhaust gas supplied to the catalytic combustor.

The solid oxide fuel cell system according to the present invention is capable of initial driving with a minimum amount of heat, and after initial driving, thermal self-supporting operation and temperature control of the entire system and each component, the heat utilization of the system itself is very high, The system can be miniaturized and lightweight, and there is an advantage of having a reduced system construction cost.

Hereinafter, a solid oxide fuel cell system of the present invention will be described in detail with reference to the accompanying drawings. The drawings introduced below are provided by way of example so that the spirit of the invention to those skilled in the art can fully convey. Accordingly, the present invention is not limited to the drawings presented below and may be embodied in other forms. Also, throughout the specification, like reference numerals designate like elements.

Hereinafter, the technical and scientific terms used herein will be understood by those skilled in the art without departing from the scope of the present invention. Descriptions of known functions and configurations that may be unnecessarily blurred are omitted.

As shown in FIG. 1, a solid oxide fuel cell system according to the present invention includes a reformer 10 for reforming a liquid hydrocarbon-based raw material to generate a hydrogen-rich reformed gas; A heater 10 'attached to the reformer outer wall to warm the reformer; A desulfurizer 20 for removing sulfur components from the reformed gas to generate reformed gas from which sulfur is removed; A solid oxide fuel cell stack 40 which generates electricity from the reformed gas and air from which sulfur is removed; A catalytic combustor 50 for combusting the exhaust gas (outlet An (out)) of the anode discharged from the solid oxide fuel cell stack 40 and the exhaust gas (outlet Ca (out)) of the cathode; And a complex heat exchanger 30 in which heat exchange between the combustion gas and the reformed gas from which sulfur is supplied to the solid oxide fuel cell stack 40 and air is performed is performed.

The solid oxide fuel cell system according to the present invention is a system in which external energy is not consumed separately for the initial operation and normal operation of the system except for the heater 10 'for raising the temperature of the reformer. By using heat exchange of the chemical reaction energy of the hydrocarbon-based raw material and air as the raw material and the chemical reaction energy by the composite heat exchanger 30, the initial driving and the normal operation of the system are possible.

Solid oxide fuel cell system according to the present invention is provided with a heater (10 ') for heating the reformer 10 by generating joule heat supplied with electricity, the rear end of the reformer 10 and the composite heat exchanger (30) ) Is characterized in that the desulfurizer 20 is provided at the front end.

Specifically, a reformer 10 is supplied with a liquid hydrocarbon-based raw material to generate a hydrogen-rich reformed gas, and a heater 10 'is attached to the reformer outer wall to raise the reformer to an initial ignition temperature. A desulfurizer 20 is provided at the rear end of the reformer 10 to receive the reformed gas discharged from the reformer 10 to remove sulfur components to generate fuel gas.

The air to be supplied to the solid oxide fuel cell stack 40 and the fuel gas discharged from the desulfurizer 20 are supplied to the solid oxide fuel cell stack 40 through the composite heat exchanger 30, wherein the composite heat exchanger is performed. The unit 30 receives a high temperature combustion gas generated and discharged from the catalytic combustion device 50 and performs heat exchange between the combustion gas, the air, and the fuel gas.

The complex heat exchanger (30) is a single heat exchanger, characterized in that heat exchange of hot combustion gas and air, hot combustion gas and fuel gas is performed simultaneously.

The solid oxide fuel cell stack 40 receives the fuel gas heated in the composite heat exchanger 30 to the anode gas inlet An (in) and receives the air heated in the composite heat exchanger 30 in the cathode gas inlet. It is supplied as (Ca (in)) to generate electricity.

The solid oxide fuel cell stack 40 is a fuel gas (electrochemical reaction in which an electrochemical reaction is performed) and a fuel gas introduced through the anode gas inlet An (in) through an anode gas outlet An (out). And the air introduced through the cathode gas inlet Ca (in) through the cathode gas outlet Ca (out) (including unreacted fuel gas not performed) (air and electricity in which the electrochemical reaction was performed). Exhaust of unreacted air, in which no chemical reaction has been carried out.

The solid oxide fuel cell stack 40 receives a high temperature fuel gas and air heated by the complex heat exchanger 30 to generate electricity by a normal electrochemical reaction (operating temperature of the solid oxide fuel cell). The temperature of the solid oxide fuel cell stack 40 is increased until the unreacted fuel gas and unreacted air are discharged from the anode gas outlet An (out) and the cathode gas outlet Ca (out) during the temperature increase process of the solid oxide fuel cell stack 40. Then, the solid oxide fuel cell stack 40 heated up to a normal operating temperature by the fuel gas and air heated in the composite heat exchanger 30 is the anode gas outlet (An (out)) and the cathode gas outlet ( Ca (out)) discharges fuel gas and air after the normal electrochemical reaction, respectively.

Hereinafter, the cathode discharge gas refers to a gas discharged through the cathode gas outlet Ca (out) regardless of whether the solid oxide fuel cell stack 40 is normally operated, and the anode discharge gas is a solid oxide fuel cell stack 40. It means the gas discharged through the anode gas outlet (An (out)) regardless of whether or not the normal operation of).

The catalytic combustor 50 receives the cathode exhaust gas and the exhaust gas of the anode to combust the combustion gas to generate a high temperature combustion gas, and the combustion gas generated by the catalytic combustor 50 is supplied to the complex heat exchanger 30. Heat exchange with reforming gas and air.

Preferably, the solid oxide fuel cell stack 40, the reformer 10, the heater 10 ′, the desulfurizer 20, the catalytic combustion unit 50 and the composite heat exchanger 30 constituting the solid oxide fuel cell system. ) Is provided in one hot box 60, which may be made of a thermally insulating ceramic material.

Figure 2 is another example of a solid oxide fuel cell system configuration according to the present invention, based on the above-described system based on Figure 1, a raw material supply pump for supplying the hydrocarbon-based raw material (raw material) to the reformer 10 (14); A water supply pump 15 for supplying water to the reformer; An air supply MFC (Mass Flow Controller) for controlling the flow rate of air supplied to the reformer; A cathode MFC (13) for controlling a flow rate of air supplied to the cathode gas inlet (Ca (in)) of the solid oxide fuel cell stack 40; Vent valves 17 provided in front of the anode gas inlet An (in) of the solid oxide fuel cell stack 40 to control a flow rate of the fuel gas supplied to the solid oxide fuel cell stack 40. First vent valve); And it is preferable that the spray nozzle 16 for mixing and spraying the air and the raw material is supplied to the reformer.

The air is compressed and stored in a bomb (bombe) can be supplied without a separate supply pump by the pressure in the bomb, the MFC (11 ~ 13) for controlling the flow rate of the air to the reformer 10 each raw material And an MFC 11 for controlling the flow rate of the air supplied to the spray nozzle 16 for mixing and spraying the air, and an MFC 12 for controlling the flow rate of the air supplied to the reformer 10 independently of the spray nozzle 16. And an MFC 13 for controlling the flow rate of the air supplied to the complex heat exchanger 30.

The MFC 11 for controlling the flow rate of the air supplied to the spray nozzle 16 controls the amount of air and fuel mixture to atomize the liquid fuel through the spray nozzle 16 and is required for the liquid fuel reforming reaction. It takes part in the amount of air. The MFC 12 which controls the flow rate of the air supplied to the reformer 10 independently of the spray nozzle 16 may adjust the amount of air required for the reforming reaction in addition to the amount of air supplied to the spray nozzle 16. The main role is to supply

As shown in FIG. 2, since the air supplied to the composite heat exchanger 30 is supplied to the solid oxide fuel cell stack 40 through heat exchange with a high temperature combustion gas, the flow rate of air supplied to the composite heat exchanger 30 is controlled. The MFC 13 controls the flow rate of the air supplied to the cathode gas inlet Ca (in).

The liquid hydrocarbon-based raw material is supplied to the reformer 10 through the raw material supply pump 14, mixed with air through the spray nozzle 16, and sprayed into the reformer 10.

The water is supplied to the reformer 10 through the water supply pump 15, although not shown in the figure, one end is connected to the water supply pump 15 and the other end is a water supply pipe connected to the reformer The water supplied by the water supply pump 15 is preferably introduced into the reformer 10 as water vapor by heat exchange at a contact surface between the water supply pipe and the outer wall of the reformer 10 contacted with each other.

To this end, the water supply pipe is made of a metal, preferably stainless steel, which is easily heat exchanged with the reformer 10 outer wall, and in order to widen the contact area between the water supply pipe and the reformer 10, The shape surrounding the outer wall of the reformer 10 is preferable.

3 to 4 are views showing the characteristics of the solid oxide fuel cell system according to the present invention capable of initial driving with a minimum amount of heat and thermal independence. FIG. 4 is an extended view of FIG. 3.

In FIG. 3 to FIG. 4, a device shown in red among the devices in the hot box 60 means a heating state (heated state) that has not reached a normal state, and a device shown in red outside the hot box 60 operates. It means that the device is operating in a state other than normal operation state, and the blue colored device means normal operation state, the red arrow means abnormal fluid state, and the blue arrow indicates normal operation state. Means the state of fluid.

The steady state is a gas reformed through a reformer, a gas desulfurized through a desulfurizer, a gas heated through a heat exchanger, a gas discharged after an electrochemical reaction through a solid oxide fuel cell, a reformer in which a reforming reaction is performed, and a desulfurization reaction. This means a desulfurizer to be performed, a complex heat exchanger to perform heat exchange, a solid oxide fuel cell to generate electricity, and the like, and the abnormal state means a state of a device and a state of a fluid other than the above-described normal state.

As shown in FIG. 3 (a), the reformer 10 of the solid oxide fuel cell system according to the present invention is 1 to 200 to 250 ° C. (primary heating temperature or initial ignition temperature) by the heater 10 '. The temperature is gradually increased, and after being heated to the initial ignition temperature by the heater 10 ', as shown in Figure 3 (b) by the raw material supply pump 14 and the air supply MFC (11, 12) The raw material and air are supplied to the reformer 10 under the conditions of complete oxidation, so that the raw material-air is free of ignition (not ignition by an external device that triggers ignition such as a heating wire). Thereby the reformer is heated to an operating temperature.

The complete oxidation reaction condition is a condition in which the hydrocarbon-based fuel supplied to the reformer reacts with air (oxygen in the air) to be completely combusted, and specifically, the air is supercharged so that a reaction such as the following formula (1) occurs.

C _n H _m + (n + m / 4) O ₂ = nCO ₂ + (m / 2) H ₂ O ---- Formula (1)

(N and m are each one or more natural numbers)

Hydrocarbon-based fuel and air supplied to the reformer 10 heated to the initial ignition temperature by the heater 10 'under complete oxidation reaction conditions are ignited and spontaneously ignited without the aid of a catalyst. It is heated up to the operating temperature secondary.

When the reformer 10 is raised to an operating temperature by no-ignition spontaneous combustion, the reforming reaction for reforming the hydrocarbon-based raw material to hydrogen-rich gas is normally performed in the reformer 10 as shown in FIG. ), The reformed gas is discharged.

At this time, as shown in Fig. 3 (a) and 3 (b) the time of supplying the hydrocarbon-based raw material and air to the reformer 10 is after the first temperature rise is completed, the hydrocarbon to the reformer 10 When the system raw material and air are supplied and spontaneous ignition occurs, heating of the reformer 10 using the external heat source (heater, 10 ') is stopped.

In detail, when the reformer 10 is raised to an operating temperature by spontaneous ignition of the hydrocarbon-based raw material, normal reforming may be performed. In order to reform the hydrocarbon-based raw material into a hydrogen-rich reformed gas, it is supplied under a complete oxidation reaction condition. The supply of hydrocarbon-based raw materials and air is changed to reforming conditions.

In detail, when the reformer 10 is raised to an operating temperature (500 to 600 ° C.) at which a normal reforming reaction may be performed, the reformer 10 is supplied with hydrocarbon-based fuel, air, and water, which are reactants under autothermal reforming conditions. The amount of hydrocarbon-based fuel and water may be controlled by the raw material supply pump 14 and the water supply pump 15, respectively, between the raw material supply pump 14 and the reformer 10 and between the water supply pump 15 and the water supply pump 15. Flow regulators between the reformer 10 may be further provided, respectively, of course.

Hydrogen-rich reformed gas can be obtained by supplying reactants (hydrocarbon-based fuel, air and water) to the reformer 10 heated to the normal operating temperature by spontaneous ignition under normal reforming conditions (thermal reforming reaction conditions). In one example, the reactant feed under modified conditions is SH Yoon, IY Kang, JM Bae. It can be performed with reference to "Effects of ethylene on carbon formation in diesel autothermal reforming" (J of Power Sources, 2008 (33), 4780-4788). At this time, the supply ratio of the reactants (hydrocarbon-based fuel, air and water supply ratio) is preferably supplied in a condition that can sustain the reaction to maintain the autothermal reforming reaction temperature.

As a practical example, the temperature of the reformer is maintained by the reaction heat generated in the autothermal reforming reaction by continuously supplying the reactants to the reformer under the conditions of H ₂ O / C = 2, O ₂ /C=0.68, GHSV = 12,500. However, this is only one example, and of course, it can be properly adjusted in the reactant feed rate for conventional autothermal reforming.

Preferably, when converting the reactant supplied to the reformer 10 from the complete oxidation reaction condition to the autothermal reforming reaction condition, after supplying water from the maintained complete oxidation reaction condition to the autothermal reforming reaction condition, the air flow rate is adjusted and To adjust the flow of fuel. This is to suppress the carbon deposition during the conversion of the reactant feed ratio, and for this purpose, not only the conversion order of the reactants described above, but also the transition time, the holding time of the transition stage, and the like are preferably accumulated.

At this time, the reformer 10 is heated to the operating temperature (500 to 600 ℃) by the non-ignition spontaneous combustion to perform the reforming reaction temperature is maintained by the reaction heat generated during the autothermal reforming reaction by fuel, air and steam, The continuous reforming reaction is carried out without supplying any external heat.

Thereafter, as shown in FIG. 3C, the reformer 10 performs a normal reforming reaction, receives a reactant under the reforming conditions, generates a reformed gas of hydrogen-rich, and is generated by the reformer 10. The reformed gas is supplied to the desulfurizer 20.

At this time, the desulfurizer 20 is heated by the hot reforming gas supplied to the desulfurizer 20. Specifically, the initial desulfurizer 20 begins to be heated by its own heat of reforming gas, and as the desulfurizer 20 is heated, desulfurization containing sulfur compounds and ZnO together with the reforming gas itself heat discharged from the reformer 10. The heat of reaction generated by the catalytic adsorption exothermic reaction between the catalysts is maintained at a temperature (300 to 500 ° C.) where the heating and normal desulfurization reaction is performed. Therefore, a separate heating device for heating the desulfurizer 20 is unnecessary and no external heat is consumed.

The reformed gas supplied to the desulfurizer 20 by the normal reforming reaction of the reformer 10 is discharged through the desulfurizer 20 regardless of whether or not the desulfurization reaction is carried out in the desulfurizer 20, the desulfurizer 20 The reformed gas and air discharged through the MFC 13 for the cathode are supplied to the combined heat exchanger (30).

In detail, the desulfurization reformer 20 or the partial desulfurization reforming gas is supplied to the complex heat exchanger 30 in the process of raising the temperature to the normal operating temperature by the reaction gas of the reforming gas and the desulfurization reaction. In operation 20 at a normal operating temperature, the desulfurized reformed gas is supplied to the combined heat exchanger 30. Hereinafter, the gas discharged from the desulfurizer 20 and supplied to the composite heat exchanger 30 is also referred to as a reforming gas.

Since the high temperature combustion gas is not supplied to the complex heat exchanger 30 when the initial system is driven, the reformed gas and air supplied from the desulfurizer 20 to the complex heat exchanger 30 are solid oxide fuels without temperature change. The reformed gas and air supplied to the battery stack 40 and bypassed the solid oxide fuel cell stack 40 at room temperature (low temperature) as shown in FIG. 50).

The anode discharge gas and the cathode discharge gas discharged from the solid oxide fuel cell stack 40 are burned by ignition-free spontaneous combustion in the catalyst combustor 50.

The catalytic combustor 50 is provided with a noble metal catalyst containing palladium or platinum (Pd, Pt), without receiving a separate external heat source, the exhaust gas introduced into the catalytic burner 50 is the noble metal catalyst under the It is ignited and spontaneously ignited by the heat of the anode exhaust itself to produce hot combustion gases.

This is because the reformed gas heated to a constant temperature by the temperature of the reformer 10 is supplied to the solid oxide fuel cell stack 40 through the desulfurizer 20 and the complex heat exchanger 30, and then the low stack 40. As it is bypassed by the temperature and flows into the catalytic combustor 50, it is spontaneously ignited by the heat of the reforming gas itself under the noble metal catalyst to spontaneously ignite to produce a high temperature combustion gas.

Although FIGS. 2 to 4 illustrate an example in which the reformed gas discharged from the desulfurizer is supplied to the catalytic combustor 50 by bypassing the solid oxide fuel cell stack 40, the solid oxide fuel cell of the present invention. The system includes a gas outlet of the desulfurizer 20 and a gas inlet of the catalytic combustor 50 and an anode gas inlet of the solid oxide fuel cell stack 40 to facilitate spontaneous combustion of the initial catalytic combustor. It is further provided with a three way valve (connecting An (in)) to selectively supply the reformed gas discharged from the desulfurizer 20 to the catalytic combustion device 50 or the solid oxide fuel cell stack. Therefore, the reformed gas discharged from the desulfurizer 20 through the three-way valve before the spontaneous ignition of the initial catalytic combustion device 50 drives the solid oxide fuel cell stack 40. There is a feature that is supplied directly to the catalytic combustor 50 without passing through.

At this time, after the catalytic combustion device 50 is spontaneously ignited by the reformed gas itself heat discharged from the desulfurization unit 20, the catalytic combustion device 50 in the desulfurizer 20 through the three-way valve as described above. It is preferable to stop the supply of reformed gas directly to the furnace, and similarly, the reformed gas bypassing the solid oxide fuel cell stack 40 is supplied to the catalytic combustor 50.

As shown in FIG. 4 (d), the complex heat exchanger 30 supplied with the high temperature combustion gas has a heat exchanger for heating the reform gas and the air supplied by the cathode MFC 13 through the desulfurizer 20. As shown in FIG. 4E, the high temperature reformed gas and the high temperature air heated by the composite heat exchanger 30 may cause the solid oxide fuel cell stack 40 to have a normal reaction temperature (600 to 800 ° C.). Heated to.

The high temperature reformed gas and the high temperature air heat-exchanged with the combustion gas by the composite heat exchanger 30 heats up the solid oxide fuel cell stack 40 and while the solid oxide fuel cell stack 40 is heated, The reformer 10 has a temperature of 700 to 900 ° C. as the raw material is switched from the complete oxidation condition to the reforming condition at an operating temperature (500 to 600 ° C. at a temperature point of 500 to 600 ° C. through an exothermic reaction that is a self-thermal reforming reaction by fuel, air and steam. The desulfurizer 20 heated to the normal operating temperature (300 to 500 ° C.) of the desulfurizer 20 by the heat of the reforming gas is catalytically adsorbed between the normal sulfide and the ZnO desulfurization catalyst. The temperature is maintained by the reaction heat generated during the reaction, so that the continuous desulfurization reaction is performed even without supplying external heat.

As shown in FIG. 4E, the solid oxide fuel cell stack 40 is gradually heated by a high temperature reformed gas and high temperature air heated by the complex heat exchanger 30 and supplied to the cathode and the anode, respectively. Since the reformed gas supplied to the solid oxide fuel cell stack 40 is supplied to the catalytic combustor 50 in an unreacted state, The heat of combustion generated during spontaneous ignition under the noble metal catalyst in the catalytic combustor 50 is controlled by the supply amount of the solid oxide fuel cell reformed gas.

Accordingly, the solid oxide fuel cell stack 40 may be formed by using a vent valve 17 (first vent valve) provided in front of the anode gas inlet An (in) of the solid oxide fuel cell stack 40. Controlling the flow rate of the reformed gas (fuel gas when the desulfurizer operates normally) and supplying the solid oxide fuel cell stack 40 by controlling the flow rate of the reformed gas (fuel gas when the desulfurizer operates normally). The heating rate of the solid oxide fuel cell stack 40 is controlled by controlling the supply amount (flow rate) of the reformed gas supplied to the catalytic combustion device 50 by passing.

Generation of reformed gas by reformer 10, generation of fuel gas (sulfur-reformed reformed gas) by desulfurizer 20, heat exchange between fuel gas (reformed gas) and combustion gas, heat exchange between air and combustion gas, The supply of hot fuel gas (reformer gas) and air heated by heat exchange to the solid oxide fuel cell stack 40, the temperature rise of the solid oxide fuel cell stack 40 by hot fuel gas (reformer gas) and air The cycle of generating high temperature combustion gas by combustion of exhaust gas discharged from the solid oxide fuel cell stack 40 is repeated, and the solid oxide fuel cell stack 40 is continuously heated up to the reaction temperature (600 to 800 ° C.). do.

As shown in FIG. 4 (f), when the solid oxide fuel cell stack 40 is heated up to a reaction temperature (600 to 800 ° C.), normal electrochemistry of hydrogen, carbon monoxide, methane and the like contained in the reformed gas with oxygen in the air The reaction takes place and electricity is generated to bring the solid oxide fuel cell stack (and system) to normal operation.

After the predetermined temperature is raised as described above, a reformer 10 and a desulfurizer 20 for performing continuous reforming and desulfurization reaction by an exothermic reaction are provided, and a high temperature combustion gas and solid oxide fuel cell stack 40 are provided. Catalytic combustor (50) for burning the exhaust gas discharged from the composite heat exchanger (30) and the solid oxide fuel cell stack (40) for heating up the fuel gas (reformed gas) and air supplied to the gas (50) The solid oxide fuel cell system of the present invention includes the energy of the system itself (including hydrocarbon-based raw materials and materials such as air) except for the amount of external heat required to raise the reformer 10 to the point of ignition free ignition. Since the initial drive is made by using, there is an advantage that the initial drive of the system with a minimum amount of heat.

3 to 4, the solid oxide fuel cell system according to the present invention in the normal driving state in which the initial driving is completed may be thermally independent operation, and the temperature of each of the solid oxide fuel cell stack, the reformer, and the catalytic combustion device is adjustable.

In detail, the reformer 10 performs exothermic reaction through autothermal reforming under a noble metal catalyst, which is Pt, Rh, Ru, Pd, Au, or a mixture thereof, so that no additional external heat source is generated by reaction heat generated during the reforming reaction. It is possible to continuously reform, and the desulfurizer 20 is provided at the rear end of the reformer 10 so that exothermic reaction of the catalytic adsorption reaction of sulfur compounds is carried out under a desulfurization catalyst, preferably a ZnO catalyst, so It can be continuously desulfurized without a separate external heat source, the solid oxide fuel cell stack 40 can also be continuously operated without a separate external heat source due to the reaction heat by the electrochemical oxidation reaction, the catalytic burner 50 is a solid If there is an unreacted fuel in the anode of the oxide fuel cell stack 40, the non-ignition spontaneous ignition is performed by the heat of the exhaust gas itself. Of the normal combustion is performed when the unreacted reformed gas is discharged with no external heat source.

Therefore, the solid oxide fuel cell system of the present invention has a feature capable of thermally independent operation without an external heat source after the normal driving.

At this time, the temperature of each of the solid oxide fuel cell stack 40, the catalytic burner 50, the reformer 10, and the desulfurizer 20 constituting the system may be controlled, and the temperature of the solid oxide fuel cell stack 40 may be controlled. By controlling the flow rate of the air flowing into the stack 40 by using the cathode MFC 13, regardless of the supply amount of fuel gas, the electrochemical oxidation by the oxygen of the cathode of the solid oxide fuel cell stack 40 The heat generated by the reaction is controlled.

That is, when the temperature of the solid oxide fuel cell stack 40 is too high, the amount of air (oxygen) supplied to the cathode of the solid oxide fuel cell stack 40 is reduced by using the cathode MFC 13. The amount of heat generated by the fuel cell stack 40 is reduced. In addition, the temperature of the solid oxide fuel cell stack 40 may be adjusted by controlling the flow rate of the reformed gas flowing into the solid oxide fuel cell stack 40 by using a vent valve 17 (first vent valve). You can also control it.

The temperature of the reformer 10 and the desulfurizer 20 provided in the solid oxide fuel cell system is controlled by controlling the flow rate of the fuel flowing into the reformer 10 using the raw material supply pump 14. The heat generated by the reforming reaction of the reformer 10 is controlled according to the flow rate of the hydrocarbon-based raw material flowing into the reformer 10, so that the temperature of the reformer 10 can be adjusted, and the flow rate of the reformed gas discharged from the reformer 10. This control is also performed to control the heat generated by the desulfurization reaction of the desulfurizer 20.

The temperature of the catalytic combustor 50 included in the solid oxide fuel cell system may be adjusted by adjusting the flow rate of the fuel flowing into the reformer 10 and the flow rate of the air flowing into the stack 40. More preferably, the flow rate of the fuel flowing into the reformer 10 by the raw material supply pump 14, the flow rate of the fuel gas flowing into the stack 40 using the vent valve 17 and the first vent valve, and the MFC for the cathode By controlling the flow rate of the air supplied to the stack 40 by the (13) it is possible to adjust the temperature of the catalytic burner (50).

In detail, in the catalytic combustor 50, unreacted hydrogen, carbon monoxide, methane, and hydrocarbon substances in the exhaust gas discharged from the anode of the solid oxide fuel cell stack 40 react with the oxygen in the exhaust gas discharged from the cathode. The temperature of the catalytic combustor 50 may be controlled by controlling a relative supply flow rate ratio of the fuel gas supplied to the solid oxide fuel cell stack 40 and air (oxygen).

In addition, as shown in FIGS. 2 to 3, a vent valve 18 and a second vent valve are further provided at a lower end of the anode outlet An (out) of the solid oxide fuel cell, and the fuel exhaust gas may be discharged. The temperature of the catalyst combustor 50 may be controlled by controlling the flow rate of the anode discharge gas flowing into the catalytic combustor 50, and the stack 40 and the catalyst combustor 50 may be controlled by the vent valve (the second vent valve 18). ) Temperature can be adjusted independently.

As described above, the reformer 10, the desulfurizer 20, the catalytic combustion device 50, and the solid oxide fuel cell stack 40 each have a flow rate of air controlled by the MFC 13 for the cathode, a vent valve 17. , The flow rate of the fuel gas controlled by the first vent valve), the flow rate of the hydrocarbon-based raw material controlled by the raw material supply pump 14, and the discharge of the anode gas regulated by the vent valve 18 (the second vent valve). It is characterized in that it is controlled through the supply flow rate (the feed flow rate to the catalyst burner).

Therefore, the internal temperature of the hot box is also adjusted by the flow rate of air regulated by the MFC 13 for the cathode, the flow rate of fuel gas regulated by the vent valve 17 and the first vent valve, and the raw material supply pump 14. And the flow rate of the hydrocarbon-based raw material and the supply flow rate of the anode exhaust gas controlled by the vent valve 18 (the second vent valve) to the catalytic combustor.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is to be understood that the invention is not limited to the disclosed embodiments, but, on the contrary, Those skilled in the art will recognize that many modifications and variations are possible in light of the above teachings.

Therefore, the spirit of the present invention should not be limited to the described embodiments, and all of the equivalents or equivalents of the claims as well as the claims to be described later will belong to the scope of the present invention. .

1 is a configuration diagram of a solid oxide fuel cell system according to the present invention;

2 is another configuration diagram of a solid oxide fuel cell system according to the present invention;

3 is a view showing the initial operation of the solid oxide fuel cell system according to the present invention,

4 is an enlarged view of the drawing of FIG.

* Description of the symbols for the main parts of the drawings *

10: reformer 20: desulfurizer

30: composite heat exchanger 40: solid oxide fuel cell stack

50 catalyst burner 60 hot box

10 ': burner

Claims (8)

A reformer that receives a liquid hydrocarbon-based raw material and generates a hydrogen-rich reformed gas; A heater attached to the reformer outer wall to warm the reformer to an initial ignition temperature; A desulfurizer which receives fuel gas discharged from the reformer and removes sulfur to generate fuel gas; A complex heat exchanger for raising a temperature of air and fuel gas discharged from the desulfurizer; A solid oxide fuel cell stack configured to generate electricity by receiving the fuel gas heated in the complex heat exchanger through a cathode gas inlet and receiving the air heated in the complex heat exchanger through a cathode gas inlet; And A catalytic combustor configured to generate combustion gas by receiving and combusting the exhaust gas of the cathode and the anode discharged from the solid oxide fuel cell stack; It is configured to include, The complex heat exchanger is a heat exchange of the combustion gas; and the fuel gas and air; And said solid oxide fuel cell stack, reformer, heater, desulfurizer, catalytic burner and composite heat exchanger are provided in one hot box. The method of claim 1, The solid oxide fuel cell system includes a raw material supply pump for supplying the hydrocarbon-based raw material to the reformer; A water supply pump for supplying water to the reformer; A mass flow controller (MFC) for supplying air to control a flow rate of air supplied to the reformer; And an MFC for controlling the flow rate of air supplied to the cathode gas inlet of the solid oxide fuel cell stack. The reformer is heated to an ignition temperature by the heater, and then the raw material and air are supplied to the reformer under the conditions of complete oxidation by the raw material supply pump and the air supply MFC, and the raw material-air is not supplied. A solid oxide fuel cell system, characterized by heating to an operating temperature of a reformer by ignition spontaneous ignition. 3. The method of claim 2, And the solid oxide fuel cell stack is heated to a reaction temperature by hot fuel gas and air discharged from the complex heat exchanger. 3. The method of claim 2, The solid oxide fuel cell system further includes a first vent valve in front of the anode gas inlet of the solid oxide fuel cell stack, and supplies the fuel to the solid oxide fuel cell stack by the first vent valve. Solid oxide fuel cell system, characterized in that the flow rate of the gas is controlled. The method of claim 4, wherein The solid oxide fuel cell system may further include a second vent valve at a rear end of an anode gas outlet of the solid oxide fuel cell stack, and the solid oxide fuel cell stack is supplied to the catalytic combustor by the second vent valve. Solid oxide fuel cell system, characterized in that the flow rate of the exhaust gas discharged from the anode of the control. 3. The method of claim 2, The reformer further comprises a spray nozzle, the solid oxide fuel cell system, characterized in that the spray and the raw material and the mixture is mixed sprayed into the reformer. The method of claim 6, Water supplied to the reformer is one end is connected to the water supply pump and the other end is supplied through a water supply pipe connected to the reformer, And the water is introduced into the reformer into water vapor by heat exchange at a contact surface between the water supply pipe and the outer wall of the reformer. The method of claim 5, A temperature of each of the reformer, the desulfurizer, the catalytic combustor, and the solid oxide fuel cell stack may control the flow rate of the raw material supplied to the reformer; An MFC for controlling the flow rate of air supplied to the cathode gas inlet of the solid oxide fuel cell stack; And a first vent valve for controlling the flow rate of the fuel gas supplied to the solid oxide fuel cell stack and a second vent valve for controlling the flow rate of the anode exhaust gas supplied to the catalytic combustor. Battery system.

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