JPH06176784A - Condensed water recovery device of fuel cell - Google Patents

Abstract

PURPOSE:To keep the life of an ion exchange treaatment device long by keeping the amount of heat exchange by means of a condensation heat exchanger at a fixed level regardless of change in air temperature, and whereby not increasing the amount of recovered water and the amount of phosphoric acid even when the air temperature is low, in the condensed water recovery device of a fuel cell, in which the exhausted air of the fuel cell is cooled by cooling water in the condensation heat exchanger, for recovery, and phosphoric acid is removed by the ion exchange treatment device, and the water is supplied to cooling water for fuel cell. CONSTITUTION:The flow of cooling water fed to a condensation heat exchanger 2 by a fixed flow pump 4 is kept at a fixed level, and a flow control valve 12 provided on a bypass piping 11 communicated to cooling water piping 9 in which cooling water is flowed to the condensation heat exchanger 2, and to a hot water piping 10 in which hot water from the condensation heat exchanger 2 is flowed, is controlled by a water temperature control means 13, according to the temperature of the cooling water fed to the condensation heat exchanger 2. The temperature of the cooling water is kept constant by controlling the flow of the hot water to be mixed with the cooling water, and the amount of heat exchange at the condensation heat exchanger 2 is kept constant.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a condensed water collecting apparatus for a fuel cell, which collects and purifies water contained in the exhaust air of the fuel cell and purifies the water to supply the cooling water for the fuel cell.

[0002]

2. Description of the Related Art FIG. 5 shows, for example, JP-A-62-29186.
FIG. 5 is a configuration diagram showing a conventional condensed water recovery device for a fuel cell disclosed in Japanese Patent Laid-Open No. 5 and Japanese Patent Laid-Open No. 2-10664. In FIG. 1, reference numeral 1 denotes a fuel cell having a fuel electrode and an air electrode for obtaining DC power, and a reformed gas obtained by a reaction between a fuel and a reforming raw material steam in a reformer (not shown) is used as a fuel electrode. At the same time as reacting with air to obtain DC power, exhaust air is discharged from the air electrode.

Reference numeral 2 is a condensation heat exchanger for cooling the water in the exhaust air from the air electrode of the fuel cell 1 by heat exchange with cooling water to condense water to obtain condensed water, and 3 is heat in the condensation heat exchanger 2. Cooling towers 4 for cooling the cooling water that has become hot water by the exchange are constant flow rate pumps for circulating the cooling water through the condensing heat exchanger 1 and the cooling tower 3.

Reference numeral 5 denotes a degassing tank for degassing recovered water for collecting the condensed water obtained in the condensation heat exchanger 2 and gas components such as carbon dioxide gas in city water from the outside to obtain deaerated water. This is an ion exchange treatment device for purifying deaerated water obtained in the deaeration tank 5 with an ion exchange resin to obtain pure water.

Numeral 7 separates steam and water generated by cooling the fuel cell 7 to obtain cooling water for cooling the fuel cell 7 and the reforming raw material steam necessary for the reaction in the reformer.
Pure water obtained by the ion exchange treatment device 6 is supplied as makeup water for the cooling water of the fuel cell 7, and 8 is the cooling water for fuel cell obtained by the steam separator 7. It is a fuel cell cooling water pump that circulates into the.

Reference numeral 9 denotes a cooling water pipe through which cooling water flows from the cooling tower 3 to the condensation heat exchanger 2, and 10 denotes cooling water which has become warm water due to heat exchange in the condensation heat exchanger 2 from the condensation heat exchanger 2. It is a hot water pipe that flows to the cooling tower 3.

Next, the operation of the above configuration will be described. The exhaust air from the air electrode of the fuel cell 1 is condensed by the heat exchanger 2
Is cooled by heat exchange with the cooling water supplied to the condensing heat exchanger 2 by the constant flow pump 4 and the water in the exhaust air is condensed with phosphoric acid scattered from the fuel cell electrolyte to be condensed water. Obtained as.

The recovered water from which the condensed water is recovered is introduced into the deaeration tank 5 and deaerated to become deaerated water, which is then introduced into the ion exchange treatment device 6. The ion exchange treatment device 6 removes the phosphate ions in the degassed water with an ion exchange resin to convert the degassed water into pure water and supplies it to the steam separator 7. As a result, the fuel cell 7 consumed as steam for reforming in the steam separator 7
Cooling water is replenished.

When the estimated amount of supplementary water is insufficient with only the recovered water, city water is supplied to the degassing tank 5 to make up for the shortage of the recovered water.

On the other hand, the cooling water supplied to the condensation heat exchanger 2 becomes hot water by heat exchange and is introduced into the cooling tower 3. The hot water cooled in the cooling tower 3 becomes cold water and is supplied to the condensation heat exchanger 2 again.

[0011]

In the conventional condensate water recovery apparatus for a fuel cell, the temperature of the cooling water in the condensing heat exchanger 2 changes as the temperature changes seasonally. Since the amount of heat exchange changes, the amount of water recovered from the condensation heat exchanger 2 changes and the amount of phosphoric acid removed by the ion exchange treatment device also changes. That is, when the temperature of the cooling water is low such as in winter, the heat exchange amount of the condensation heat exchanger 2 increases and the recovered water amount increases, so that the amount of phosphoric acid removed by the ion exchange treatment device 7 increases.

Phosphoric acid in the recovered water is removed from the recovered water by neutralizing the anion phosphate ion with the cation of the ion exchange resin in the ion exchange resin device 7, but it should be removed at a low temperature. When the amount of phosphoric acid is large, there is a problem that the cations of the ion exchange resin, which are necessary for neutralizing the phosphate ions, are immediately lost and the life of the ion exchange resin is shortened.

The present invention has been made in order to solve the above problems, and provides a condensed water recovery device for a fuel cell which can keep the life of the ion exchange resin long even when the temperature is low such as in winter. With the goal.

[0014]

According to a first aspect of the present invention, there is provided a condensed heat recovery device for a fuel cell, which comprises a heat of condensation for collecting recovered water by cooling exhaust air from an air electrode of the fuel cell with cooling water to condense it. The exchanger is provided with a cooling water circuit that converts hot water generated by heat exchange in the condensation heat exchanger into cooling water by a cooling means and supplies the cooling water to the condensation heat exchanger, and collects recovered water from the condensation heat exchanger. In a condensed water recovery device for a fuel cell, which is purified through an ion exchange treatment device for purification to obtain makeup water to a steam separator, in the cooling water circuit, cooling from the cooling means to the condensation heat exchanger A bypass pipe for supplying hot water flowing in the cooling water pipe into the cooling water pipe by communicating with the cooling water pipe through which the water flows and the hot water pipe through which the hot water flows from the condensation heat exchanger to the cooling means. Provided in And a water temperature control means for measuring the temperature of the cooling water and controlling the flow control valve according to the measured value to keep the temperature of the cooling water flowing to the condensation heat exchanger constant. It is a thing.

Further, a condensed water recovery apparatus for a fuel cell according to a second aspect of the present invention is a condensing heat exchanger for collecting recovered water by cooling and condensing exhaust air from an air electrode of the fuel cell with cooling water, Ion exchange for purifying recovered water obtained from the condensation heat exchanger, which is provided with a cooling water circuit for converting hot water generated by heat exchange in the condensation heat exchanger into cooling water by a cooling means and supplying the cooling water to the condensation heat exchanger. In a condensed water recovery device for a fuel cell, which is purified through a processing device to obtain makeup water to a steam separator, a flow rate measuring means for measuring a flow rate of the cooling water in the cooling water circuit, and the cooling Water temperature measuring means for measuring the temperature of water, and the condensation in order to make the heat exchange amount of the condensing heat exchanger constant with respect to the temperature measured value of the cooling water based on the measured values of the flow rate measuring means and the temperature measuring means. Cooling supplied to the heat exchanger It is obtained by a flow control means for controlling the flow rate of.

[0016]

In the condensed water recovery apparatus for a fuel cell according to the first aspect of the present invention, the temperature of the cooling water supplied to the condensation heat exchanger is measured by the water temperature control means, and the cooling water is provided in the bypass pipe according to the measured value. The temperature of the cooling water flowing to the condensing heat exchanger is kept constant by controlling the flow rate control valve provided to control the flow rate of the warm water mixed with the cooling water. Thereby, the amount of heat exchange in the condensation heat exchanger is made constant, and the amount of water recovered in the condensation heat exchanger purified by the ion exchange treatment device is made constant.

In the condensate water recovery apparatus for a fuel cell according to a second aspect of the present invention, the heat exchange amount of the condensing heat exchanger is constant based on the measured values of the flow rate measuring means and the temperature measuring means by the flow rate controlling means. The flow rate of the cooling water supplied to the condensation heat exchanger is controlled in accordance with the measured temperature value of the cooling water. As a result, the amount of water recovered from the condensation heat exchanger purified by the ion exchange treatment device is kept constant.

[0008]

Embodiments of the present invention will be described below with reference to the drawings. Example 1. First Embodiment FIG. 1 is a configuration diagram showing a first embodiment of the present invention. In the figure, 1 to 10 have the same configuration as that of FIG. 5, and 11 denotes the hot water flowing through the hot water pipe 10 and the cooling water pipe 9.
It is a bypass pipe that feeds back inside and mixes into the cooling water.

Reference numeral 10 is a flow control valve provided in the bypass pipe 11, 13 is provided in the cooling water pipe 9 between the constant flow pump 4 and the condensation heat exchanger 2, and cooling is supplied to the condensation heat exchanger 2. Measure the water temperature and adjust the flow rate control valve 12 according to the measured value.
It is a water temperature control means for controlling.

Next, the operation of the above configuration will be described. The water temperature control means 13 measures the temperature of the cooling water supplied to the condensation heat exchanger 2, controls the flow rate adjusting valve 12 so that the measured value is always constant, and passes through the bypass pipe 11 to the inside of the cooling pipe 9. Control the flow rate of hot water mixed with the cooling water of.

The cooling water is controlled to a constant temperature in this way and is supplied to the condensing heat exchanger 2 at a constant flow rate by the constant flow rate pump 4.

Therefore, since the flow rate and the temperature of the cooling water supplied to the condensation heat exchanger 2 are always kept constant, the heat exchange amount in the condensation heat exchanger 2 is always constant. for that reason,
Since the amount of water recovered from the heat exchanger 2 is constant regardless of the temperature, the amount of phosphoric acid removed by the ion exchange treatment device 6 is constant.

Example 2. Second Embodiment FIG. 2 is a configuration diagram of a second embodiment of the present invention. In the second embodiment, the cooling water pipe 9 is provided with a centrifugal pump 4A to circulate the cooling water. Further, a flow rate adjusting valve 12 is provided in the vicinity of the projecting port of the centrifugal pump 4a, and a flow rate measuring means 14 is provided at the outlet of the flow rate adjusting valve 12, whereby the condensation heat exchanger 2 passes through the flow rate adjusting valve 12.
Measure the flow rate of the cooling water supplied to the.

Further, temperature measuring means 13A for measuring the temperature of the cooling water 2 is provided near the cooling water inlet of the condensation heat exchanger 2, and the flow rate control valve is based on the measured value and the measured value of the flow rate measuring means 14. A flow rate controller 15 that controls the opening degree of 12 to control the flow rate supplied to the condensation heat exchanger 2 is provided.
Other configurations are the same as those in FIG.

Next, the operation of the above configuration will be described. The heat exchange amount H of the condensing heat exchanger 2 is H = KAΔT _m ...
(1), the overall heat transfer coefficient K determined by the material of the condensing heat exchanger 2, the heat transfer area A determined by the shape of the condensing heat exchanger 2, and the heating side (discharging side) of the condensing heat exchanger 2. air)
And the logarithmic average temperature difference ΔT _m between the heat receiving side (cooling water side). The logarithmic average temperature difference ΔT _m is calculated by using the temperature c of exhaust air before heat exchange, the temperature a of exhaust air after heat exchange, the cooling water temperature b before heat exchange, and the cooling water temperature d after heat exchange.
T _m = {(cd)-(ab)} / ln {(cd) /
(Ab)}.

The flow rate Q of the cooling water is Q = H / (b-
a) ... (2).

In the above equation (1), the overall heat transfer coefficient K and the heat transfer area A are constant because they are specific to the condensing heat exchanger 2, and the temperature a of the exhaust air before heat exchange and the exhaust air after heat exchange are constant. Since the air temperature c is predetermined as a process condition, the heat exchange amount H depends on the difference b-d between the cooling water temperature b before the heat exchange and the cooling water temperature d after the heat exchange.

Therefore, from the equation (1), when the heat exchange amount H is constant, the cooling water temperature b before the heat exchange is the water temperature measuring means 13A.
If the heat exchange amount H of the condensation heat exchanger 2 is set to a constant value in Eq. (2), the cooling water amount Q will be the cooling water temperature before the heat exchange. b, that is, the cooling water temperature measured by the water temperature measuring means 13A.

Therefore, since the heat exchange amount H of the condensation heat exchanger 2 is constant, the cooling water flow rate Q with respect to the cooling water temperature b is
As shown by the solid line in FIG. 3, the characteristics increase as the cooling water temperature b increases.

Therefore, the flow rate controller 15 is preset with the cooling water amount Q corresponding to the cooling water temperature b obtained from the characteristics of FIG. 3, and the flow rate controller 15 determines the cooling water temperature measured by the water temperature measuring means 13A. The opening degree of the flow rate adjusting valve 12 is controlled so that the cooling water amount measured by the flow rate measuring means 14 becomes a set value. Thereby, the cooling water is supplied to the condensation heat recovery device 2 at a required flow rate.

As described above, in the second embodiment, the amount of cooling water is controlled according to the temperature of the cooling water to make the heat exchange amount in the condensation heat exchanger 2 constant, so that the condensation heat exchanger is irrespective of the temperature. The amount of water recovered from 2 is constant, so the amount of phosphoric acid removed by the ion exchange treatment device 6 is kept constant.

Example 3. FIG. 4 is a configuration diagram showing a third embodiment of the present invention. The third embodiment is a flow control valve 12
Is provided in the bypass pipe 11 that communicates with the cooling water pipe 9 and the hot water pipe 10. Other configurations are the same as those in FIG.

Next, the operation will be described. The cooling water amount corresponding to the cooling water temperature measured by the water temperature measuring means 13A is obtained from the characteristics of FIG. 3 and set in the flow rate controller 15. The flow rate controller 15 controls the opening degree of the flow rate control valve 12 so that the cooling water flow rate measured by the flow rate measurement means 14 becomes a set value in accordance with the cooling water temperature measured by the water temperature measurement means 13A, and the cooling water piping The amount of cooling water flowing from 9 to the hot water pipe 10 is controlled.

In this way, by indirectly controlling the flow rate of the cooling water supplied to the condensation heat exchanger 2 in accordance with the temperature of the cooling water flowing through the condensation heat exchanger 2, the condensation heat exchanger 2 The heat exchange amount of is kept constant. As a result, the amount of recovered water obtained from the condensation heat exchanger 2 becomes constant regardless of the temperature, so that the amount of phosphoric acid removed by the ion exchange treatment device 6 becomes constant.

Example 4. In the second embodiment, the opening degree of the flow rate adjusting valve 12 is controlled by the flow rate controller 15, but the rotational speed of the centrifugal pump 4A may be controlled without using the flow rate adjusting valve 12. For this, for example, the rotation speed of the motor that drives the centrifugal pump 4A is controlled by the flow rate controller 15, or a slip joint is provided between the motor and the centrifugal pump 4A and is controlled by the flow rate controller 15. It is achieved by

By controlling the rotational speed of the centrifugal pump 4 as described above, the power cost can be reduced.

[0037]

As described above, the condensate water recovery apparatus for a fuel cell according to claim 1 of the present invention provides cooling water to the condensing heat exchanger according to the temperature of the cooling water supplied to the condensing heat exchanger. Control the flow control valve provided in the bypass pipe that communicates with the cooling water pipe that flows through and the hot water pipe through which the hot water from the condensation heat exchanger flows, and control the flow rate of the hot water mixed with the cooling water. By keeping the temperature constant, even if the temperature changes, the temperature of the cooling water is kept constant and the amount of heat exchange in the condensation heat exchanger is constant, so even when the temperature is low such as in winter, Since the amount of recovered water in the condensation heat exchanger purified by the ion exchange treatment device does not increase and the amount of phosphoric acid removed does not increase, it is possible to maintain the life of the ion exchange resin of the ion exchange treatment device for a long time. .

According to the second aspect of the present invention, in the condensed water recovery apparatus for a fuel cell, the condensing heat exchanger is connected to the condensing heat exchanger according to the temperature measurement value of the cooling water so that the heat exchange amount of the condensing heat exchanger becomes constant. By controlling the flow rate of the cooling water to be supplied, the amount of heat exchange is constant even if the temperature changes, so even when the temperature is low such as in winter, the condensation heat exchanger is purified by the ion exchange treatment device. Since the amount of recovered phosphoric acid does not increase and the amount of phosphoric acid to be removed does not increase, there is an effect that the life of the ion exchange resin of the ion exchange treatment device can be maintained for a long time.

[Brief description of drawings]

FIG. 1 is a configuration diagram showing a first embodiment of the present invention.

FIG. 2 is a configuration diagram showing a second embodiment of the present invention.

FIG. 3 is a characteristic diagram for explaining the operation of the second embodiment of the present invention.

FIG. 4 is a configuration diagram showing a third embodiment of the present invention.

FIG. 5 is a configuration diagram showing a conventional condensed water recovery device for a fuel cell.

[Explanation of Codes] 1 Fuel Cell 2 Condensation Heat Exchanger 3 Cooling Tower 4A Centrifugal Pump 6 Ion Exchange Treatment Device 7 Gas / Water Separation 9 Cooling Water Pipe 10 Hot Water Pipe 11 Bypass Pipe 12 Flow Control Valve 13 Water Temperature Control Means 13A Water Temperature Measuring means 14 Flow rate measuring means 15 Flow rate controlling means

Claims (2)

[Claims] 1. A condensing heat exchanger for collecting recovered water by cooling and condensing exhaust air from an air electrode of a fuel cell with cooling water,
Ion exchange for purifying recovered water obtained from the condensation heat exchanger, which is provided with a cooling water circuit for converting hot water generated by heat exchange in the condensation heat exchanger into cooling water by a cooling means and supplying the cooling water to the condensation heat exchanger. In a condensed water recovery device for a fuel cell, which is purified through a treatment device to obtain makeup water for a steam separator, cooling in which cooling water flows from the cooling means to the condensation heat exchanger in the cooling water circuit. A bypass pipe, which is connected to a water pipe and a hot water pipe in which hot water flows from the condensation heat exchanger to the cooling means, and which supplies hot water flowing in the hot water pipe into the cooling water pipe, and the bypass pipe A flow rate control valve and water temperature control means for measuring the temperature of the cooling water and controlling the flow rate control valve according to the measured value to keep the temperature of the cooling water flowing to the condensation heat exchanger constant. Featuring Condensed water recovery system of a fuel cell that. 2. A condensing heat exchanger for collecting recovered water by cooling exhaust air from an air electrode of a fuel cell with cooling water and condensing it.
Ion exchange for purifying recovered water obtained from the condensation heat exchanger, which is provided with a cooling water circuit for converting hot water generated by heat exchange in the condensation heat exchanger into cooling water by a cooling means and supplying the cooling water to the condensation heat exchanger. In a condensed water recovery device for a fuel cell, which is purified through a processing device to obtain makeup water to a steam separator, a flow rate measuring means for measuring a flow rate of the cooling water in the cooling water circuit, and the cooling Water temperature measuring means for measuring the temperature of the water, and the condensation in order to make the heat exchange amount of the condensation heat exchanger constant with respect to the temperature measured value of the cooling water based on the measured values of the flow rate measuring means and the temperature measuring means. A condensate water recovery apparatus for a fuel cell, comprising: a flow rate control means for controlling a flow rate of cooling water supplied to the heat exchanger.