JPH07254425A - Heat retaining device for piping and equipment in fuel gas system in fuel cell power generation system - Google Patents

Abstract

PURPOSE:To provide a heat retaining device in a fuel cell power generation system for preventing reliquefaction of fuel gas flowing through pipings and devices in a fuel gas system through which vaporized fuel gas of liquid fuel flows. CONSTITUTION:An electric heater 2 is wound around the surface of pipings 1 in a fuel gas system, a signal of a detected temperature at a temperature detector 6 provided on the surface is inputted to a control device 7, and a switch 4 is on/off controlled by the control device 7, so the fuel gas is controlled at a specified temperature at which it can be prevented from reliquefaction. Similar heat retaining devices are provided on valves, flow control valves, and heat exchangers provided in the middle of the pipings to control them at the specified temperature.

Description

Detailed Description of the Invention

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fuel cell power generation system mainly composed of a fuel cell and a fuel reformer, in which a raw fuel gas obtained by vaporizing a liquid raw fuel flows or stays. This relates to gas system piping and equipment heat insulation devices.

2. Description of the Related Art A fuel cell produces electric power by a cell reaction of hydrogen and oxygen. Normally, hydrogen is reformed from a hydrocarbon-based or alcohol-based raw fuel gas into a hydrogen-rich gas in a fuel reformer. The reformed gas is used and oxygen is air. Therefore, the fuel cell power generation system is configured with the fuel reformer and the fuel cell as main components, and supplies the reformed gas generated by the fuel reformer to the fuel cell.
By the way, the fuel reformer includes a reformer equipped with a reaction tube filled with a reforming catalyst, a burner for burning the fuel to heat the reaction tube with combustion heat, and a raw fuel gas of a hydrocarbon type. In this case, a desulfurizer provided before the reformer to desulfurize the sulfur content contained in the raw fuel gas, and a desulfurizer provided after the reformer to remove carbon monoxide in the reformed gas from the reformer. And a carbon monoxide transformer for reducing the concentration. Here, the raw fuel gas supplied to the reformer is a liquid raw fuel such as propane, which has a small volume and is easy to transport.
Since liquid raw fuels such as butane, methanol, and naphtha are transported from the place where they are produced to the place of consumption, these raw fuels are obtained by vaporization with an evaporator or the like. The raw fuel gas as described above passes through a raw fuel gas system including pipes, valves arranged in the middle of the pipe, a flow control valve, a heat exchanger, and the like to a reformer, and the raw fuel is hydrocarbon-based. In some cases, the steam is reformed by being supplied to the reaction tube of the reformer through the desulfurizer. In addition,
When starting the fuel cell power generation system, for example, it is necessary to warm up the reaction tube of the reformer in a cold state to a predetermined temperature suitable for carrying out the reforming reaction, and in this case also, the raw fuel gas is used as fuel. The reformer is warmed up by the combustion heat of the combustion of the raw fuel gas in the burner of the reformer. At this time, the raw fuel gas is also used for supporting combustion formed by the pipes and equipment as described above. It is supplied to the burner through a raw fuel gas system.

As described above, the raw fuel gas for reforming and auxiliary combustion that flows or stays in the pipes and equipment of the raw fuel gas system for reforming and the raw fuel gas system for supporting heat. Is a liquid raw fuel that has been vaporized, so the atmosphere of the piping and equipment of the raw fuel gas system for reforming and the raw fuel gas system for combustion is low, and the support that supports the piping and equipment is If it is cooled by heat transfer to the stand, the cooled pipes,
There is a problem that the raw fuel gas is reliquefied in the equipment part and the supply amount of the raw fuel gas cannot be kept constant. Further, when the pipe has a device for adjusting the flow rate, for example, a flow control valve, the raw fuel gas is adiabatically expanded when flowing from a narrow flow passage area narrowed by the flow control to a wide flow passage area. There is a problem in that the supply amount of the raw fuel gas cannot be kept constant as in the above case by being cooled and reliquefied. An object of the present invention is, in a fuel cell power generation system, the raw fuel gas flowing through piping and equipment of a raw fuel gas system in which a raw fuel gas obtained by vaporizing a liquid raw fuel flows,
Piping of raw fuel gas system of fuel cell power generation system that can prevent reliquefaction caused by cooling when staying,
An object of the present invention is to provide a device heat retention device.

To solve the above problems, according to the present invention, a raw fuel gas obtained by vaporizing a liquid raw fuel in a fuel cell power generation system comprising a fuel cell and a fuel reformer flows. , Or a pipe of a raw fuel gas system that stays, a pipe of a raw fuel gas system of a fuel cell power generation system that keeps the equipment warm, or a heat insulating device of the equipment, a heating means that is arranged on the surface of the pipe or the equipment and heats these And a temperature detector that detects the temperature of the heated portion, and the heating by the heating means is controlled from the deviation between the temperature detected by this detector and the target value of the predetermined temperature that can prevent re-liquefaction of the raw fuel gas. And control means. In the above description, the heating means is an electric heater. The heating means is a heat transfer tube through which hot water or steam generated in the fuel cell power generation system flows.

In the fuel cell power generation system, the raw fuel gas obtained by vaporizing the liquid raw fuel is connected to the raw fuel gas system including the pipe and the valve, flow control valve, heat exchanger, and other devices provided in the middle of the pipe. It flows or stays again. However, the atmosphere of the raw fuel gas system is low temperature,
Because the raw fuel gas is reliquefied by being cooled by adiabatic expansion when flowing from a narrow flow passage area to a wide flow passage area by being throttled by a flow control valve etc. for flow control, the raw fuel gas flowing through the raw fuel gas System pipes, heating means for equipment, electric heaters that cover the surface of pipes as this means, or heat transfer tubes through which hot water or steam generated during power generation of a fuel cell power generation system flows, and heating by this heating means And a temperature detector for detecting the temperature of the portion where the temperature of the electric heater is provided, and from the deviation between the temperature detected by the temperature detector by the control means and the target value of the predetermined temperature that can prevent re-liquefaction of the raw fuel gas, By controlling the flow rate of hot water or steam flowing through the output or heat transfer pipe to heat the raw fuel gas flowing to the pipes and equipment of the raw fuel gas system or staying, the temperature is controlled to the predetermined temperature to control the raw fuel gas. To prevent liquefaction.

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a partial perspective view of a pipe of a raw fuel gas system including a heat retaining device in a fuel cell power generation system according to an embodiment of the present invention. In FIG. 1, a pipe 1 is a pipe through which vaporized raw fuel gas flows, and an electric heater 2 is wound to cover the surface of the pipe 1. In addition, 3 is an electric heater 2
Power source 4, electric heater 2 and lead wire 5 connected to the electric heater 2.
It is a switch that turns on-off the circuit consisting of. The temperature detector 6 detects the temperature of the pipe 1 heated by the electric heater 2. The controller 7 receives the signal of the temperature detected by the temperature detector 6, and controls the switch 4 via the relay 8 from the deviation between this detected temperature and the target value of the predetermined temperature at which the raw fuel gas can be prevented from being reliquefied. Control on-off. The heat insulating material 9 is provided so as to cover the surface of the pipe 1 with the electric heater 2 and the temperature detector 6. With such a configuration, the pipe 1 is heated by the electric heater 2, and the control device 7 detects a temperature detected by the temperature detector 6 and a target value of a predetermined temperature for preventing the raw fuel gas flowing in the pipe 1 from being reliquefied. By controlling the switch 4 on-off via the relay 8 from the deviation of 1, the temperature of the pipe 1 is controlled to the predetermined temperature, so that the raw fuel gas is not reliquefied. FIG. 2 is a partial perspective view of piping of a raw fuel gas system including a heat retaining device in a fuel cell power generation system according to another embodiment of the present invention. In FIG. 2, a heat transfer tube 10 made of, for example, a copper tube, in which hot water or steam generated in the fuel cell power generation system flows so as to cover the surface of the tube 1, is wound, and a flow path control valve 11 is provided in a conduit 13 connected to the heat transfer tube 10. The flow control valve 1 is provided based on a deviation between a temperature detected by the temperature detector 6 and a target value of a predetermined temperature capable of preventing reliquefaction of the raw fuel gas flowing through the pipe 1.
1 is the same as that of FIG. 1 except that a control device 12 for controlling 1 is provided. With such a configuration, hot water or steam generated during power generation of the fuel cell power generation system is caused to flow through the heat transfer pipe 10 to heat the pipe 1, and the temperature detected by the temperature detector 6 and the raw fuel gas are regenerated by the control device 12. Since the temperature of the pipe 1 is controlled to the predetermined temperature by controlling the flow rate control valve 11 from the deviation from the target value of the predetermined temperature that can prevent liquefaction, the raw fuel gas is not reliquefied. Electric heater 2 above
Alternatively, the heat insulating device that heats the pipe 1 by hot water or steam flowing through the heat transfer pipe 10 to control the temperature of the pipe 1 to a predetermined temperature that can prevent re-liquefaction of the raw fuel gas is used not only in the pipe 1 but also in the middle of the pipe. Re-liquefaction of the raw fuel gas can be prevented by providing the valve, the flow rate control valve, and the heat exchanger. The following is an example of applying the above heat retaining device to the piping and equipment of the raw fuel gas system in a fuel cell power generation system. FIG. 3 is a system diagram of a fuel cell power generation system including a reformer for steam reforming a gas rich in hydrogen using butane gas having a high condensation point of hydrocarbon as a raw fuel gas. Figure 3
In the above, 15 is a reformer equipped with a reaction tube 16 and a burner 17, 18 is a desulfurizer for desulfurizing sulfur contained in raw fuel,
Reference numeral 19 is a carbon monoxide transformer, 20 is a fuel cell including an electrolyte 21, and a fuel electrode 22 and an air electrode 23 that sandwich the electrolyte 21, 24
Is a heat exchanger, and 25 is a steam ejector. The raw fuel gas supply system 27 includes a flow rate control valve 28 and is connected to the inlet of the desulfurizer 18 via the heat exchanger 24. The desulfurization raw fuel gas supply system 30 is connected to the outlet of the desulfurizer 18 and the inlet of the reaction tube 16 via a steam ejector 25 and a heat exchanger 24. The auxiliary combustion raw fuel gas supply system 31 includes a flow rate control valve 32 and is connected to the burner 17 of the reformer 15.
The steam reformed gas supply system 34 is connected to the outlet of the reaction tube 16 of the reformer 15 and the inlet of the carbon monoxide shift converter 19 via the heat exchanger 24. The reformed gas supply system 35 is connected to the outlet of the carbon monoxide shift converter 19 and the fuel electrode 22 of the fuel cell 20 with a stop valve 36. The off-gas exhaust system 37 is connected to the fuel electrode 22 of the fuel cell 20 and the burner 17 of the reformer 15 with a stop valve 38. The bypass system 39 bypasses the fuel cell 20 and includes a stop valve 40, which is connected to the reformed gas supply system 35 and the off-gas discharge system 37. The air supply system 41 includes a blower 42 and a flow rate control valve 43, and is connected to the air electrode 23, and the off-air discharge system 44 is connected to the air electrode 23 of the fuel cell 20. The recycle system 45 is branched from the steam reformed gas supply system 34 and is provided with a stop valve 46 to join the raw fuel gas supply system 27 upstream of the heat exchanger 24. The combustion air supply system 47 includes a blower 48 and a flow rate control valve 49, and is connected to the burner 17 of the reformer 15. The exhaust gas exhaust system 50 joins the off-air exhaust system 44 from the combustion exhaust gas outlet of the reformer 15. Reference numeral 51 is a steam supply system for supplying steam to the steam ejector 25 for driving. Here, the pipe leading to the desulfurizer 18 via the heat exchanger 24 of the raw fuel gas supply system 27 shown by the solid line with a broken line in the figure in which the vaporized raw fuel gas flows, the desulfurization of the desulfurization raw fuel gas supply system 30 Piping from the container 18 to the Sutim ejector 25, raw fuel gas supply system 3 for auxiliary combustion
1 to the burner 17 of the reformer 15 and from the stop valve 46 of the recycle system 45 where the raw fuel gas stays due to the closing of the start stop valve 46 to the confluence with the raw fuel gas supply system 27. The pipe is provided with a heat retention device including the electric heater, the temperature detector, and the control device described above. In addition, the flow control valve 28 provided in the middle of these pipes,
32, the stop valve 46, and the heat exchanger 24 are also provided with the heat retaining device. Here, the heat retaining device provided in the pipe is appropriately divided and provided independently in consideration of the ambient temperature, the heat capacity, etc., and the pipe of the raw fuel gas supply system 27 is divided into eight parts to obtain the desulfurization raw fuel gas supply system 30. The pipe is divided into two parts, and the pipe of the auxiliary combustion raw fuel gas supply system 31 is divided into two parts.
In the flow rate control valves 28 and 32, the flow of the raw fuel gas is throttled by the valve opening degree and then adiabatically expanded to cool the flow rate. Therefore, a temperature detector is installed in the pipe section at the outlet of the flow rate control valves 28 and 32. The set temperature for mounting and keeping the temperature higher is about 10 ° C. higher than a predetermined temperature that can prevent reliquefaction of the raw fuel gas in a normal pipe. With such a configuration, when starting the fuel cell power generation system, the raw fuel gas composed of butane is fed to the raw fuel gas for auxiliary combustion via the raw fuel gas for auxiliary combustion 31 in order to warm up the reformer 15 in the cold state. The burner 1 is controlled by the flow rate control valve 32 as gas.
7, the pressure is increased by the blower 48 via the combustion air supply system 47, the flow rate is controlled by the flow rate control valve 49, and combustion is performed by the combustion air supplied to the burner 17. And
The combustion heat heats the reaction tube 16 of the reformer 15 to a predetermined temperature suitable for the reforming reaction. After the temperature of the reaction tube 16 is raised, the raw fuel gas is caused to flow into the raw fuel gas supply system 27, and the heat exchanger 2
4, It supplies to the steam ejector 25 via the desulfurizer 18. Then, the raw fuel gas is sucked by the driving steam passing through the steam supply system 51 by the steam ejector 25 and supplied to the reaction tube 16 together with the steam for steam reforming. At this time, the stop valve 36 of the reformed gas supply system 35 and the stop valve 38 of the off gas discharge system 37 are closed, and the stop valve 40 of the bypass system 39 is opened until the steam-reformed gas is supplied to the fuel cell 20. The steam-reformed gas from the reaction tube 16 is supplied to the burner 17 through the bypass system 39 and the off-gas discharge system 37 and used as fuel. When the raw fuel gas flows through the raw fuel gas supply system 27, the recycle system 45 between the confluence of the raw fuel gas supply system 27 and the recycle system 45 and the stop valve 46 of the recycle system 45 has the raw fuel gas. Stays. In the operation of the fuel cell power generation system, the stop valve 40 of the bypass system 39 is closed, the stop valve 46 of the recycle system 45, the stop valve 36 of the reformed gas supply system 35, and the stop valve 38 of the off gas discharge system 37 are opened, It is performed as follows. At this time, the auxiliary combustion raw fuel gas supply system 3
The raw fuel gas for assisting combustion passing through 1 is not supplied to the burner 17. Raw fuel gas supply system 2 consisting of butane
7 and the temperature is raised by heat exchange through the heat exchanger 24, and then supplied to the desulfurizer 18. At this time, a part of the hydrogen-rich reformed gas from the carbon monoxide shift converter 19, which will be described later, is added to the raw fuel gas supplied to the desulfurizer 18 through the recycle system 45. Therefore, the hydrogen-added raw fuel gas in the reformed gas is desulfurized by the desulfurizer 18 to remove the sulfur content contained in the raw fuel gas. The desulfurized raw fuel gas is sucked into the steam ejector 25 driven by the steam passing through the desulfurization raw fuel gas supply system 30 and the steam supply system 51, mixed with the steam, and heated by heat exchange in the heat exchanger 24. After doing
It is supplied to the reaction tube 16 of the reformer 15. On the other hand, reformer 1
The burner 17 of No. 5 has a fuel electrode 22 of a fuel cell 20 described later.
Off gas is supplied through the off gas exhaust system 37. Then, this off gas is boosted by the blower 48 through the combustion air supply system 47 to the burner 17, and the flow control valve 4
It is burned by the combustion air whose flow rate is controlled by 9, and the reaction tube 16 is heated by this combustion heat. It should be noted that the combustion exhaust gas is mixed with the off air from the fuel cell 20 flowing through the off air exhaust system 44 via the exhaust gas exhaust system 50 and is exhausted. Here, the raw fuel gas mixed with steam flowing through the heated reaction tube 16 is steam-reformed into a gas rich in hydrogen. The steam-reformed gas is cooled by the heat exchanger 24 and then supplied to the carbon monoxide shift converter 19, which contains carbon monoxide contained in the steam-reformed gas and poisoning the catalyst of the fuel cell. Reduce the concentration. In the fuel cell 20, the reformed gas having a low carbon monoxide concentration from the carbon monoxide shift converter 19 and the air whose pressure is increased by the blower 42 through the air supply system 41 and whose flow rate is controlled by the flow rate control valve 43 are supplied. Generate a battery reaction to generate electricity. The heat generated during power generation of the fuel cell 20 is removed by cooling water flowing through a cooling plate (not shown) provided in the cell body, and the operating temperature of the fuel cell 20 is maintained. The off air from the fuel cell 20 is
It is discharged to the outside through the off-air discharge system 44. As described above, when the raw fuel gas flows through the system as described above, the raw fuel gas supply system 27, the desulfurization raw fuel gas supply system 30, and the recycle system 45 in which the raw fuel gas at start-up stays are shown in the solid line with the broken line as described above. , Auxiliary fuel raw fuel gas supply system 31, flow control valve 2
Since the heat retaining device is provided for the 8, 32, the stop valve 46, and the heat exchanger 24 as described above, even if the atmosphere has a low temperature, heat is transferred to the support base of the equipment, or cooling is performed by adiabatic expansion. Since the raw fuel gas is heated at a predetermined temperature by being given heat from the heat retaining device, reliquefaction of the raw fuel gas can be prevented.

As is apparent from the above description, according to the present invention, in the fuel cell power generation system, the raw fuel gas system piping in which the raw fuel gas obtained by vaporizing the liquid raw fuel flows,
A heating means, an electric heater as this means, a heat transfer tube through which hot water or steam generated in the fuel cell power generation system flows, is attached to the surface of the equipment, the temperature is detected by a temperature detector, and the raw fuel gas is reliquefied by the control means. Since the temperature is controlled to a predetermined temperature that can be prevented, the atmosphere is low,
It is possible to prevent re-liquefaction of the raw fuel gas even if the raw fuel gas is cooled by heat transfer to the equipment support table or by adiabatic expansion caused by restriction of the flow rate by flow rate control.

[Brief description of drawings]

FIG. 1 is a partial perspective view of a pipe of a raw fuel gas system provided with a heat insulating device according to an embodiment of the present invention.

FIG. 2 is a partial perspective view of a pipe of a raw fuel gas system provided with a heat insulating device according to another embodiment of the present invention.

FIG. 3 is a system diagram of a fuel cell power generation system including a raw fuel gas system in which a heat insulating device is installed in a pipe and equipment of a raw fuel gas supply system according to an embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Piping 2 Electric heater 6 Temperature detector 7 Control device 10 Heat transfer pipe 11 Flow control valve 12 Control device

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Takashi Watanabe 1-1, Tanabe Nitta, Kawasaki-ku, Kawasaki-shi, Kanagawa Fuji Electric Co., Ltd. No. 1 inside Fuji Electric Co., Ltd.

Claims (3)

[Claims] 1. A fuel cell for maintaining the temperature of piping and equipment of a raw fuel gas system in which a raw fuel gas obtained by vaporizing a liquid raw fuel flows or stays in a fuel cell power generation system including a fuel cell and a fuel reformer. In a pipe of a raw fuel gas system of a power generation system and a heat insulating device of a device, a heating means disposed on the surface of the pipe and the device for heating them, a temperature detector for detecting the temperature of a heated portion, and this detection Of the fuel cell power generation system, comprising: a control means for controlling heating by the heating means based on a deviation between a temperature detected by the reactor and a target value of a predetermined temperature capable of preventing re-liquefaction of the raw fuel gas. Fuel gas system piping, equipment heat insulation device. 2. The heat insulation device for piping and equipment of a raw fuel gas system of a fuel cell power generation system according to claim 1, wherein the heating means is an electric heater. 3. The raw fuel gas system of a fuel cell power generation system according to claim 1, wherein the heating means is a heat transfer tube through which hot water or steam generated in the fuel cell power generation system flows. A heat insulation device for piping and equipment.