JPH0217696B2 - - Google Patents

Description

[Detailed Description of the Invention] [Field of Industrial Application] This invention utilizes exhaust gas energy from a system to drive a turbine, and supplies the air required by the system by a compressor installed coaxially with the turbine. This relates to a method for starting a turbo compressor system.

[Conventional technology]

This type of turbo compressor system does not waste the exhaust gas energy of the system.
Energy is effectively recovered within the system, and a typical example is a fuel cell power generation system. This fuel cell power generation system will be described below as an example.

Fuel cell power generation systems have advantages over conventional steam power generation, such as higher efficiency and better environmental protection, and have been actively developed in recent years with the aim of putting them into practical use. A fuel cell power generation system consists of a fuel cell body consisting of an air electrode, a fuel electrode, and an electrolyte layer, and a reformer that reforms hydrocarbon fuel such as natural gas and supplies hydrogen gas as fuel to the fuel cell body. , a turbo compressor that supplies air to the fuel cell body and reformer. The performance of the fuel cell main body tends to improve as the pressure of the reactant gas increases, and therefore the operating pressures of fuel, air, and each reactant gas are maintained at, for example, about 4 to 6 kg/cmg. At this time, a large amount of power is required to compress the air, but this power is provided by the turbine of the turbo compressor, which introduces the combustion exhaust gas from the reformer and surplus air from the air electrode of the fuel cell main body. In other words, this turbo compressor uses a turbine to recover energy from the system's exhaust gas, and a coaxial compressor supplies the necessary compressed air, thereby recovering power within the system and improving system efficiency. be.

Now, in such a fuel cell power generation system, in order to start the system, it is first necessary to start the turbo compressor, but since the system exhaust gas that serves as the driving source cannot be obtained in the initial stage, some external energy must be applied. It is necessary to start up the turbo compressor. For this reason, it is common to use a compressed air supply device for startup, but as a specific conventional method, for example,
There is a device disclosed in Japanese Patent No. 17434, and an example thereof is shown in FIG. 3 in a simplified manner. In the figure,
1 is a system consisting of a fuel cell main body, a reformer, etc.; 2 is a turbine 2a that is driven by the exhaust gas from system 1 and supplies the compressed air necessary for system 1; and is arranged coaxially with this turbine 2a. 3 is an air supply pipe arranged on the inlet side of the compressor 2b of this turbo compressor 2, 4 is a valve installed in this air supply pipe 3, and 5 is a compressed air for starting. A supply device 6 supplies air from this startup compressed air supply device 5 to the air supply pipe 3 on the inlet side of the compressor 2b.
7 is a valve installed on the introduction pipe 6, 8 is an air supply pipe installed on the outlet side of the compressor 2b to supply air from the compressor 2b to the system 1, and 9 is an air supply pipe from the system 1. 10 is a turbine exhaust gas pipe that discharges the exhaust gas from the turbine 2a; 11 is a turbine bypass pipe that connects the system exhaust gas pipe 9 and the turbine exhaust gas pipe 10 by bypassing the turbine 2a; 1
2 is a turbine bypass valve installed on this turbine bypass piping 11.

Next, the starting operation of the turbo compressor 2 in the conventional system configured as described above will be explained. When starting the system, first, valve 4 is closed, valve 7 is opened, and starting compressed air supply device 5 is started. Compressed air discharged from the startup compressed air supply device 5 passes through the compressor 2b and is supplied to a reformer (not shown) in the system 1 via the air supply piping 8. In this state, fuel is introduced into the reformer of system 1 and combustion is started. The combustion exhaust gas from the reformer, i.e. from the system 1, passes through the system exhaust gas piping 9 to the turbine 2a.
After returning to the atmosphere, it is discharged to the atmosphere through the turbine exhaust gas pipe 10. During this time, the temperature of the reformer increases,
Along with this, the exhaust gas temperature also rises, and the turbo compressor 2 starts rotating at a certain point. When the exhaust gas temperature reaches a temperature sufficient to allow the turbo compressor 2 to operate on its own, the valve 4 is opened, the starting compressed air supply device 5 is stopped, and the valve 7 is closed. As a result, turbo compressor 2
obtains exhaust gas energy from system 1 and becomes self-operating. In the above process, the turbine bypass valve 12 is used to adjust the overload of the turbo compressor 2, and is adjusted in a timely manner to prevent overload. In this way, the startup of the turbo compressor 2 is completed, and after that, the required air volume is set by the turbo compressor 2 according to the request of the system 1.
Compressed air at wind pressure is supplied.

Now, one of the features of such conventional technology is that the starting air from the starting compressed air supply device 5 is supplied to the inlet side of the compressor 2b, so even in the starting operation mode, the starting air is supplied to the inlet side of the compressor 2b.
It is possible to secure a sufficient flow rate of the engine, thereby preventing surging that tends to occur during startup. Yet another feature is
Since the exhaust gas energy of the system 1 is effectively used to start up the turbo compressor 2, no other extra energy is required to start up the turbo compressor. That is,
In a fuel cell power generation system, it takes several hours to raise the temperature around the reformer, but this is done using air from the startup compressed air supply device 5,
The exhaust gas energy is used to start up the turbo compressor 2 and increase the pressure after the temperature has been raised, and the energy required to start up the turbo compressor 2 can be kept small.

[Problem that the invention seeks to solve]

However, in such a conventional configuration, the starting air from the starting compressed air supply device 5 passes through the compressor, system, and turbine in series, resulting in an extremely large pressure loss. There was a problem in that the capacity of the starting compressed air supply device 5 had to be considerably increased in order to supply the air necessary for heating. That is, since the turbo compressor 2 has not yet been started during the temperature rising process of the system, the ventilation resistance of the compressor 2b and the turbine 2a is large.
For this reason, it was necessary to increase the discharge pressure of the starting compressed air supply device 5. Furthermore, in order to start the turbo compressor 2 from a stopped state after the temperature of the system has increased, appropriate inlet gas pressure conditions of the turbine 2a (for example, about 0.5 kg/cmG) are required. The pressure loss during this time was large, and for this reason as well, it was necessary to increase the discharge pressure of the starting compressed air supply device 5.

This invention was made to solve the above-mentioned problems, and provides a turbo compressor system that can easily and stably start up a turbo compressor with a small capacity starting compressed air supply device. It is something to do.

[Means for solving problems]

The turbo compressor system according to the present invention includes compressor bypass piping that connects the inlet side piping and outlet side piping of the compressor via a valve, and compressor bypass piping that connects the inlet side piping and the outlet side piping of the turbine through the valve. A turbine bypass piping is installed to connect to the compressor bypass piping, and when the system is started, air from the startup compressed air supply device passes through this compressor bypass piping and is supplied to the system, and exhaust gas from the system is passed through this turbine bypass piping. The system is characterized in that the temperature of the system is increased. In addition, after the temperature of the system was raised, the turbo compressor was started by closing the on-off valve of the turbine bypass circuit while introducing air from the startup compressed air supply device to the compressor bypass piping.

[Effect]

In the turbo compressor system of the present invention, the compressed air from the startup compressed air supply device and the exhaust gas from the system bypass the compressor and turbine, respectively, during the temperature rise process at system startup, so that the pressure loss in the path is almost eliminated from the system. The capacity of the starting compressed air supply device can be reduced, and the energy consumption required during starting can be reduced. Furthermore, when the turbo compressor is started, the compressed air from the startup compressed air supply device is injected into the turbine bypassing the compressor, so that sufficient turbine inlet pressure can be maintained and the turbo compressor can easily start up.

[Embodiments of the invention]

An embodiment of the present invention will be described below with reference to FIG. In the figure, numerals 1 to 10 are the same as the conventional structure shown in FIG. 13 is compressor 2
A compressor bypass pipe connects between the air supply pipe 3 on the inlet side of compressor 2b and the air supply pipe 8 on the outlet side of the compressor 2b, 14 is an on-off valve installed on this compressor bypass pipe 13, and 15 is a turbine 2a. Turbine bypass piping 16 connects between the system exhaust gas piping 9 on the upstream side of the turbine 2a and the turbine exhaust gas piping 10 on the downstream side of the turbine 2a, 16 is an on-off valve installed on this turbine bypass piping 15; , 15 and the on-off valves 14, 16, the diameters are selected so that the pressure loss is sufficiently small for the passage of supply air or system exhaust gas at the time of system startup. Reference numeral 17 indicates an auxiliary combustor to compensate for the lack of turbine power; 18 indicates an air supply pipe branching from the air supply pipe 8 to supply combustion air to the auxiliary combustor 17; and 19 indicates an air supply pipe on the air supply pipe 18. This is the installed control valve. In this embodiment, an example is given in which the turbine power is insufficient for the necessary compressor load, and for this reason, an auxiliary combustor 17 is arranged in the middle of the system exhaust gas piping 9. Although the auxiliary combustor 17 is not installed in the conventional example shown in FIG. 3, the auxiliary combustor 17 is generally required due to insufficient turbine power. However, the installation of the auxiliary combustor 17 in such a system is based on conventional technology, and one example is the patent application filed in 1983-
As shown in Publication No. 202804.

Next, the operation of the embodiment shown in FIG. 1 will be explained. When starting the system, first close valves 4 and 19,
Start-up compressed air supply device 5 is started with valves 7, 14, and 16 open. The compressed air from the startup compressed air supply device 5 passes through both the compressor 2b and the compressor bypass piping 13, but since the ventilation resistance on the compressor 2b side is extremely large, most of the compressed air passes through the compressor bypass piping 1.
3 to the air supply pipe 8 and system 1
will be put into the In this state, fuel is introduced into the reformer (not shown) of system 1 and combustion is started. This combustion exhaust gas passes through the system exhaust gas piping 9, flows through the turbine 2a and the turbine bypass piping 15 in parallel, and is discharged into the atmosphere via the turbine exhaust gas piping 10 as a system exhaust gas. Also at this time, since the ventilation resistance of the turbine 2a is large, most of the exhaust gas passes through the turbine bypass pipe 15. The temperature of the system 1 is raised by configuring such a ventilation path for air and exhaust gas. With this configuration, the pressure loss in the system from the discharge side of the startup compressed air supply device 5 to the exhaust gas discharge is almost exclusively accounted for by the pressure loss within the system 1, and the pressure loss in the system is significantly reduced compared to the conventional system. can. Therefore, in this configuration, it is sufficient to prepare the startup compressed air supply device 5 with a discharge pressure that is almost equal to the pressure loss within the system 1, which reduces the equipment capacity and further reduces the energy consumption during startup. The effect of this can be obtained. Now, when the temperature of the system 1 rises and the exhaust gas temperature also rises to a certain extent, the next step is to start the turbo compressor 2. In the conventional example shown in Fig. 3, the timing for starting the turbo compressor was when the system exhaust gas temperature satisfied the conditions for starting the turbo compressor, but in the example shown in Fig. 1, the auxiliary combustor 17 was installed. Even if the energy of the system exhaust gas is not sufficient for starting the turbo compressor 2 and operating it on its own, the turbo compressor 2 can be started at any time. First, the on-off valve 16 of the turbine bypass pipe 15 is closed.
As a result, the entire amount of system exhaust gas is transferred to the turbine 2a.
However, because the ventilation resistance of the turbine 2a is large and the amount of air passing through is limited, the internal pressure of the system gradually increases due to the buffer volume effect within the system 1. In this way, when the turbine inlet pressure conditions necessary for starting the turbo compressor 2 are established, the turbo compressor 2 starts starting. At this time, if the turbine inlet temperature is insufficient to start the turbo compressor 2, combustion in the auxiliary combustor 17 may be started prior to starting. Combustion in the auxiliary combustor 17 is performed by opening the control valve 19 of the air supply pipe 18 and simultaneously supplying fuel. In such a system, the compressor 2b is bypassed for startup, so that the capacity of the startup compressed air supply device 5 can be reduced compared to the conventional system.
Once the turbo compressor 2 is started, the compressor 2b tries to start blowing air by rotation, so that the air from the starting compressed air supply device 5 comes to pass through the compressor 2b. If the on-off valve 14 of the compressor bypass piping 13 is closed when the compressor 2b starts blowing air, the pressure is ready to increase. The timing of whether or not the compressor 2b starts blowing air may be determined based on the rotation speed of the turbo compressor 2.
Alternatively, the determination can be made based on the difference between the suction pressure and the discharge pressure of the compressor 2b. After this, if combustion is not being performed in the auxiliary combustor 17, combustion is started. Due to combustion in the auxiliary combustor 17, the turbine 2a
The temperature of the inlet gas increases, the turbine power increases accordingly, the rotational speed of the turbo compressor 2 increases, and the air volume and discharge pressure of the compressor 2b increase. During this time, the compressed air from the startup compressed air supply device 5 is continuously pushed into the suction side of the compressor 2b, so that the compressor 2b has a relatively low compression ratio to ensure sufficient air volume and perform stable startup and boosting operations. be exposed. After that, when the turbine inlet gas conditions necessary for self-operation of the turbo compressor 2 are reached, valve 4 is opened to stop the starting compressed air supply device 5, and valve 7 is closed to allow the turbo compressor 2 to operate on its own. Realize the state. The starting compressed air supply device 5 may be stopped when the discharge pressure of the starting compressed air supply device 5, that is, the suction pressure of the compressor 2b has decreased to around 0 kg/cmG (atmospheric pressure). This completes the startup of the turbo compressor 2, and thereafter compressed air of the required air volume and pressure is supplied from the turbo compressor 2 according to the request of the system 1.

In the above embodiment, an example was described in which the on-off valve 14 was installed on the compressor bypass piping 13.
A check valve may be used instead of this on-off valve and the same effect can be achieved. An embodiment using a check valve is shown in FIG. In the figure, 20 indicates a check valve, and in this case, the check valve 20 is installed in a direction to prevent backflow from the air supply pipe 8 on the outlet side of the compressor 2b to the air supply pipe 3 on the inlet side of the compressor 2b. In a system using this check valve 20, the compressor 2
Since the check valve 20 is automatically closed when the compressor 2b starts blowing air, that is, when the discharge pressure of the compressor 2b exceeds the suction pressure, the embodiment shown in FIG. There is no need to close the on-off valve.

In addition, the air supply pipe 3 on the inlet side of the compressor 2b
The upper valve 4 may be replaced with a check valve, and the valve 7 on the introduction pipe 6 may be omitted, and the same effects as in the embodiments shown in FIGS. 1 and 2 can be obtained.

Furthermore, in the embodiments shown in FIGS. 1 and 2, the auxiliary combustor 17 is installed in the middle of the system exhaust gas piping 9. If energy alone is sufficient, the auxiliary combustor 17 may be omitted.

Further, in the above embodiment, an example was shown in which the turbo compressor 2 is started after the temperature of the system 1 is increased, but in the case where the auxiliary combustor 17 is installed, the turbo compressor 2 is activated at any time without waiting for the temperature of the system 1 to increase.
can be started. However, it is preferable to use the exhaust gas energy to start up the turbo compressor 2 after the temperature of the system 1 has been increased, since the capacity of the auxiliary combustor 17 can be reduced and the amount of energy consumed can be reduced.

By the way, in the above embodiment, the case where the target is a fuel cell power generation system is described, but it goes without saying that the present invention can be applied to other systems such as chemical plants, and in short, the present invention can be applied to a system using a turbo compressor. This embodiment has the same effect as the above embodiment.

〔Effect of the invention〕

As described above, according to the present invention, the compressor bypass piping connects the inlet side piping and the outlet side piping of the compressor via the valve, and the compressor bypass piping connects the inlet side piping and the outlet side piping of the turbine via the valve. By installing the turbine bypass piping, it is possible to supply the air necessary to raise the temperature of the system using a relatively small-capacity starting compressed air supply device, and it is also possible to easily and stably supply the air needed to raise the temperature of the system. can be started.

[Brief explanation of drawings]

FIG. 1 is a system diagram showing a method for starting a turbo compressor system according to an embodiment of the present invention, and FIG.
FIG. 3 is a system diagram showing a method for starting a turbo compressor system according to another embodiment of the present invention, and FIG. 3 is a system diagram showing a method for starting a conventional turbo compressor system. In the figure, 1 is a system, 2 is a turbo compressor, 2a is a turbine, 2b is a compressor,
3 is an air supply pipe, 5 is a compressed air supply device for startup, 8
is air supply piping, 9 is system exhaust gas piping, 13
is compressor bypass piping, 14 is on-off valve, 1
5 is a turbine bypass pipe, 16 is an on-off valve, 20
is a check valve. Note that the same reference numerals in the figures indicate the same or equivalent parts.

Claims (1)

[Claims] 1. A turbo compressor comprising a turbine driven by exhaust gas from the system and a compressor coaxially and directly connected to the turbine to supply compressed air necessary for the system, and an inlet of the compressor. In a turbo compressor system equipped with a starting compressed air supply device installed in a side pipe, the compressor bypass pipe connects the inlet side pipe and the outlet side pipe of the compressor via a valve, and the turbine A turbine bypass piping is installed to connect the inlet side piping and the outlet side piping via a valve, and when the system is started, air from the startup compressed air supply device is guided to the compressor bypass piping. Exhaust gas from the system is guided to the turbine bypass piping, and when the turbo compressor is started, air from the startup compressed air supply device is guided to the compressor bypass piping. A turbo compressor system characterized in that the valve of the compressor bypass piping is closed after the turbo compressor is started. 2 The valves on the compressor bypass piping are
Claim 1 characterized in that it is a check valve.
Turbo compressor system as described in section.