JP3586989B2 - Generated water recovery device for fuel cell power generator - Google Patents

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
TECHNICAL FIELD The present invention relates to a generated water recovery apparatus that effectively and efficiently collects generated water generated by a power generation operation in a fuel cell power generation apparatus.
[0002]
[Prior art]
FIG. 2 is a flow chart showing the flow of reactant gas and generated water of a fuel cell power generator conventionally used. Reaction air containing oxygen is supplied to the air electrode of the fuel cell main body 1, and a reformed gas having a high hydrogen concentration obtained by reforming a mixed gas of raw fuel and steam in the reformer 2 is used as the fuel cell main body 1. , And power is generated by an electrochemical reaction between oxygen and hydrogen. The fuel electrode off-gas containing residual hydrogen discharged from the fuel electrode is sent to the combustor 2a of the reformer 2 along with the combustion air and burned, and is used to heat the reformer 2 to promote the reforming reaction. . In the above-described electrochemical reaction, reaction product water is generated, and also when combustion is performed in the combustor 2a of the reformer 2, combustion product water is generated. Therefore, the air electrode off-gas discharged from the air electrode of the fuel cell body 1 and the combustion exhaust gas discharged from the combustor 2a are sent to the heat exchanger 3 having the cooling water pipe to be cooled, and the contained moisture is reduced. It is condensed, liquefied and collected, and the exhaust gas is taken out. The recovered water recovered by the heat exchanger 3 is used as steam mixed with the raw fuel.
[0003]
The flow rate of the reaction air supplied to the fuel cell body 1 and the flow rate of the raw fuel supplied to the fuel cell body 1 via the reformer 2 are controlled according to the power generation load. The flow rate of the supplied combustion air is also controlled in accordance with the composition and flow rate of the fuel electrode off-gas, which varies according to the power generation load, and the operating conditions of the reformer 2. Therefore, the composition and flow rate of the air electrode off-gas discharged from the air electrode and the combustion exhaust gas discharged from the combustor 2a also vary depending on the operating conditions of the fuel cell body 1. For this reason, the flow rate is adjusted in accordance with the maximum condition of the power generation load, that is, the condition in which the recovered water is maximized, so that the amount of the recovered water obtained in the heat exchanger 3 always satisfies the required amount of steam used by mixing with the raw fuel. A method is generally used in which the control valve 4 is adjusted to operate by setting the temperature and flow rate of the cooling water flowing through the cooling water pipe of the heat exchanger 3.
[0004]
[Problems to be solved by the invention]
As described above, in the generated water recovery device of the conventional fuel cell power generation device, the temperature and the flow rate of the cooling water flowing through the cooling water pipe of the heat exchanger 3 are set according to the maximum condition of the power generation load. Therefore, even if the power generation load fluctuates, a required amount of recovered water is always obtained and mixed with the raw fuel to obtain a predetermined amount of reformed gas.
[0005]
By the way, in the heat exchanger 3, the cooling water passed through the cooling water pipe is heated by heat exchange with the air electrode off-gas and the combustion exhaust gas, and is taken out as hot water. Therefore, if this hot water is used, for example, for hot water supply, waste heat is effectively used, and an efficient system can be obtained.
However, in the conventional apparatus, as described above, the condition of the cooling water flowing through the cooling water pipe is set in accordance with the maximum condition of the power generation load. Since the temperature and the flow rate of the combustion exhaust gas decrease and the temperature of the hot water taken out by heat exchange with the exhaust gas decreases, there is a disadvantage that the range that can be used as the hot water is limited.
[0006]
An object of the present invention is that even when raw fuel, reaction air or combustion air fluctuates due to fluctuations in power generation load, required generated water is recovered without excess and shortage, and water is passed for recovery. Another object of the present invention is to provide a generated water recovery device of a fuel cell power generation device in which cooling water is heated and taken out as warm water of an appropriate temperature, and heat is effectively used.
In order to achieve the above object, the present invention provides a reformer for reforming a mixed gas of raw fuel and steam into a hydrogen-rich reformed gas, and introducing the reformed gas to a fuel electrode. A product water recovery device used in a fuel cell power generation device including a fuel cell body that introduces reaction air into an air electrode to generate electricity by an electrochemical reaction, and includes a fuel air off-gas discharged from the combustion air and a fuel electrode. The combustion exhaust gas discharged after the combustion is used to heat the reformer, and the air electrode off-gas discharged from the air electrode are introduced into the product water recovery device, and cooling water piping supplied from the outside is introduced. By cooling the combustion exhaust gas and the air electrode off-gas by exchanging heat with a system, the generated water contained in the combustion exhaust gas and the air electrode off-gas is condensed and collected in the generated water recovery device, and after the generated water is collected. Exhaust gas In the produced water recovery device for discharging a scan,
(1) a flow control valve for adjusting a flow rate of a cooling water flowing through a piping system of the cooling water, a temperature detecting means for measuring a temperature of the exhaust gas, a temperature setting device for setting a temperature of the exhaust gas, and the temperature detecting means And a temperature controller that outputs a valve opening control signal to the flow control valve so that the detected temperature is controlled to the temperature set by the temperature setting device.
[0008]
(2) Further, in the generated water recovery device of the fuel cell power generation device according to (1), the temperature setting device includes a flow rate detecting means for measuring a flow rate of the raw fuel, a flow rate detecting means for measuring the flow rate of the reaction air, and A detection signal is input from at least one of the flow rate detecting means for measuring the flow rate, and the temperature is set in accordance with the detected flow rate.
[0009]
FIG. 3 is a flow chart showing the composition of gas flowing through each system corresponding to FIG. 2. CH ₄ is supplied as a raw fuel, and the molar ratio of carbon to water vapor of the mixed gas supplied to the reformer is 1; : 3, the balance when the hydrogen utilization rate in the fuel cell body was 80%, the oxygen utilization rate was 50%, and the amount of oxygen in the combustion air supplied to the combustor of the reformer was twice the required amount was shown. Things. In response to CH ₄ supplied as the raw fuel _is supplied combustion air 12.8N ₂ + 3.2O 2 reaction air and 3.2N ₂ + 0.8O _2, the heat exchanger for recovering produced water And CO ₂ + 2O ₂ + 5H ₂ O obtained by adding the air electrode off-gas (12.8N ₂ + 1.6O ₂ + 3.2H ₂ O) and the combustion exhaust gas (CO ₂ + 0.4O ₂ + 1.8H ₂ O + 3.2N ₂ ). + so that the gas composition of 16N ₂ is sent. When cooling is performed by exchanging heat with cooling water from the outside in the heat exchanger, the moisture contained in the exhaust gas is limited to the saturated steam content (2H ₂ O), and the remaining moisture (3H ₂ O) is condensed and recovered and recovered. Mixed with fuel.
[0010]
Therefore, according to the above (1), the temperature of the exhaust gas from the heat exchanger can be arbitrarily controlled to the set temperature, so that a predetermined amount of recovered water can be obtained by passing an appropriate amount of cooling water, and at the same time, Thus, it is possible to adjust the temperature so as to obtain appropriately heated warm water.
In particular, in the case of the above (2), the composition of the gas sent to the heat exchanger can be calculated from the supply amount of each gas, and the amount of water recovered by setting and controlling the temperature of the exhaust gas of the heat exchanger Can be defined. Therefore, appropriately heated warm water can be obtained more effectively.
[0011]
BEST MODE FOR CARRYING OUT THE INVENTION
FIG. 1 is a flow chart showing the flow of reaction gas and generated water of a fuel cell power generation device showing an embodiment of a generated water recovery device according to the present invention.
This embodiment is characterized by a heat exchanger 3, a thermometer 5 for detecting the temperature of the exhaust gas from the heat exchanger 3, and a cooling valve 4 for supplying cooling water to the heat exchanger 3 to obtain hot water. A water supply system, a temperature setting device 7 for setting the temperature of the heat exchanger 3, and a temperature for receiving a detection signal of the thermometer 5 and a setting signal of the temperature setting device 7 and transmitting a valve opening control signal to the flow rate regulating valve 4. A generated water recovery device 9 having a controller 6 and a flow rate detection signal of flow meters 8A, 8B, 8C provided in a combustion air supply system, a raw fuel supply system, and a reaction air supply system are used for temperature setting. Is sent to the container 7. That is, in this configuration, the set temperature of the heat exchanger 3 is calculated by the temperature setting unit 7 based on the flow rate detection signals of the flow meters 8A, 8B, 8C and the preset ratio of the raw fuel flow rate and the steam flow rate. The flow rate control valve 4 is controlled by the temperature controller 6 based on the set value, and the flow rate of the cooling water supplied to the cooling system of the heat exchanger 3 is adjusted. In the heat exchanger 3, the exhaust gas is cooled by the heat exchange between the exhaust gas and the cooling water to lower the dew point, and the condensed water is recovered as recovered water and used as steam mixed with the raw fuel. The cooling water is heated by the exhaust gas, taken out as warm water, and used, for example, for hot water supply. In the present configuration, the supply amount of the cooling water is adjusted in accordance with the operating conditions of the fuel cell power generation device as described above, so that the required recovered water is obtained without excess or shortage, and is taken out by exchanging heat with the exhaust gas. The hot water will also be adjusted so as not to be too cold.
[0012]
In the embodiment shown in FIG. 1, the combustion air flow rate detection signal, the raw fuel flow rate detection signal, and the reaction air flow rate detection signal from the three flow meters 8A, 8B, 8C are sent to the temperature setting device 7, The set temperature of the heat exchanger 3 is calculated on the basis of the following equation. However, the present invention is not limited to this configuration. For example, the fuel utilization rate (fuel Consumption rate), air-fuel ratio (reaction air flow rate and fuel flow rate), and air utilization rate (reaction air consumption rate in the fuel cell body) are set in advance, and these are set for the heat exchanger 3 in the temperature setting device 7. If it is used to calculate the set temperature, the same effect can be obtained by using only one of the flow rate detection signals of the three flow meters.
[0013]
【The invention's effect】
As described above, according to the present invention, a product water recovery device used in a fuel cell power generation device
(1) Since it is configured as described in claim 1, even when the raw fuel, the reaction air or the combustion air fluctuates due to the fluctuation of the power generation load, the required generated water is not excessive or shortage. The cooling water that is recovered and passed through for recovery is heated and taken out as hot water of an appropriate temperature, and a generated water recovery device of a fuel cell power generation device that can be effectively utilized is obtained. .
[0014]
(2) Further, if configured as described in claim 2, it is more suitable as a generated water recovery device of a fuel cell power generation device having the above performance.
[Brief description of the drawings]
FIG. 1 is a flow diagram of a reaction gas and a generated water flow of a fuel cell power generation device showing an embodiment of a product water recovery device according to the present invention. FIG. 2 is a reaction gas and generation of a conventionally used fuel cell power generation device. Flow diagram showing the flow of water [FIG. 3] Flow diagram showing the composition of gas flowing through each system shown in FIG.
DESCRIPTION OF SYMBOLS 1 Fuel cell main body 2 Reformer 2a Combustor 3 Heat exchanger 4 Flow control valve 5 Thermometer 6 Temperature controller 7 Temperature setter 8A, 8B, 8C Flow meter 9 Generated water recovery device

Claims (2)

A reformer that reforms a mixed gas of raw fuel and water vapor into a hydrogen-rich reformed gas, and a fuel cell that introduces the reformed gas into the fuel electrode and introduces reaction air into the air electrode to generate electricity by an electrochemical reaction A product water recovery device used for a fuel cell power generator including a main body,
The combustion air and the fuel electrode off-gas discharged from the fuel electrode are burned, and the combustion exhaust gas discharged after being used for heating the reformer and the air electrode off-gas discharged from the air electrode are separated into the generated water recovery device. The cooling water supplied from outside is exchanged with heat to exchange heat with the piping system to cool the combustion exhaust gas and the air electrode off gas, thereby condensing the water contained in the combustion exhaust gas and the air electrode off gas to condense the water. In the product water recovery device that is collected in the product water recovery device and discharges the gas after product water recovery as exhaust gas,
A flow rate adjustment valve for adjusting the flow rate of the cooling water flowing through the cooling water piping system,
Temperature detection means for measuring the temperature of the exhaust gas,
A temperature setting device for setting the temperature of the exhaust gas,
A temperature controller that inputs a detection signal of the temperature detection unit and outputs a valve opening control signal to the flow rate adjustment valve so that the detected temperature is controlled to a temperature set by the temperature setting device,
A water recovery apparatus for a fuel cell power generator, comprising: 2. The generated water recovery apparatus for a fuel cell power generator according to claim 1, wherein the temperature setting device is configured to measure a flow rate of the raw fuel, a flow rate detection means that measures a flow rate of the reaction air, and a flow rate of the combustion air. A fuel cell characterized in that it is configured to receive a detection signal from at least one of the flow rate detecting means among the flow rate detecting means for measuring the flow rate and to set the temperature of the exhaust gas in accordance with the detected flow rate. A generated water recovery device for a power generator.

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