JPH0217698B2 - - 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 main body and a 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/cm ² g. 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 recovers the exhaust gas energy of the system with a turbine,
By supplying the necessary compressed air with a coaxial compressor, power is recovered within the system, improving system efficiency.

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.

As a specific conventional method, for example,
There is something disclosed in Publication No. 59-202804,
Its configuration is shown in FIG. 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 exhaust gas from system 1 and supplies the compressed air necessary for system 1, and is coaxial with this turbine 2a. 3 is an air supply pipe installed on the inlet side of the compressor 2b of this turbo compressor 2, and 4 is this air supply pipe 3.
5 is an air supply pipe installed on the outlet side of the compressor 2b and supplies air from the compressor 2b to the system 1; 6 is a control valve installed in the air supply pipe 5; 7 is a control valve installed in the system 1;
8 is an auxiliary combustor provided in the middle of the system exhaust gas piping 7, and 9 is a system branched from the air supply piping 5 to supply combustion air to the auxiliary combustor 8. 10 is a control valve installed in the middle of this air supply pipe 9, 11 is a fuel supply pipe to the auxiliary combustor 8, 12 is a compressed air supply device for starting, 1
Reference numeral 3 denotes an introduction pipe that guides the air from this starting compressed air supply device 12 to the inlet air supply pipe 3 of the compressor 2b, 14 a switching valve installed in this introduction pipe 13, and 15 an air supply pipe 5 and system exhaust gas. A starting bypass pipe 16 that connects the starting bypass pipe 15 with the pipe 7 is a control valve installed in this starting bypass pipe 15 .

In addition, in the embodiment shown in Japanese Patent Application No. 59-202804, the auxiliary combustor 8 is placed in the middle of the air supply pipe 9, but this is connected to the system exhaust gas as shown in FIG. Even if it is placed in the middle of the piping 7, it is functionally equivalent.

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, the switching valve 4 and the regulating valves 6 and 10 are closed, and the switching valve 14 and the regulating valve 16 are opened, and the starting compressed air supply device 12 is started. Compressed air supply device 12 for startup
The compressed air passes through the compressor 2b, passes through the air supply pipe 5, the start-up bypass pipe 15, and the system exhaust gas pipe 7, and is input into the turbine 2a. As a result, the turbo compressor 2 is activated, and the pressure of the compressed air from the compressor 2b increases. Thereafter, the control valve 10 is opened, air is introduced into the auxiliary combustor 8, and fuel is also introduced from the fuel supply pipe 11, and combustion in the auxiliary combustor 8 is started. The combustion exhaust gas from the auxiliary combustor 8 is combined with the compressed air returning through the startup bypass pipe 15, and is input into the turbine 2a. In this way, the temperature of the gas input to the turbine 2a increases, and along with this, the turbine power increases and the discharge air pressure of the compressor 2b increases. When the temperature necessary for self-operation of the turbo compressor 2 is reached, the switching valve 4 is opened, the starting compressed air supply device 12 is stopped, and the switching valve 14 is closed. This causes the turbo compressor 2 to become self-operating. After this, control valve 6
By gradually opening the control valve 16 and gradually closing the control valve 16, the air passing through the starting bypass piping 15 is gradually switched to the system 1, and the compressed air from the compressor 2b is introduced into the system 1. In this way, startup of the turbo compressor system is completed.

[Problem that the invention seeks to solve]

However, in such a conventional configuration, when starting the turbo compressor 2, the air from the starting compressed air supply device 12 passes through the compressor 2b and then is input into the turbine 2a. There is a drawback that the turbo compressor 2 cannot be started unless the capacity of the air supply device 12 is considerably increased. That is, in order to start the turbo compressor 2 from a stopped state, it is necessary to inject air at an appropriate pressure (about 0.5 kg/cm ² G in one example) and air volume into the turbine 2a. In this state, the pressure loss when the air from the startup compressed air supply device 12 passes through the compressor 2b is extremely large. Therefore, if the startup compressed air supply device 12 does not have sufficient capacity, the turbine inlet required for startup will be Conditions could not be obtained and the turbo compressor 2 could not be started.

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

[Means for solving problems]

The turbo compressor system according to the present invention includes a compressor bypass pipe connected via a valve between an air supply pipe on the inlet side of the compressor and an air supply pipe on the outlet side of the compressor,
The turbo compressor is characterized in that, when starting up the turbo compressor, air from the starting compressed air supply device is passed through this compressor bypass piping to start up the turbo compressor.

[Effect]

In the turbo compressor system according to the present invention, when the turbo compressor is started, compressed air from the startup compressed air supply device passes through the compressor bypass piping and is input into the turbine without passing through the compressor. The pressure loss from the starting compressed air supply device to the turbine inlet is small, and therefore the turbo compressor is started up by the starting compressed air supply device having a relatively small capacity.

[Embodiments of the invention]

An embodiment of the present invention will be described below with reference to FIG. In the figure, numerals 1 to 16 are the same as the conventional system configuration described above. 17 is a compressor bypass pipe that connects the air supply pipe 3 on the inlet side of the compressor 2b and the air supply pipe 5 on the outlet side of the compressor 2b, and 18 is an on-off valve installed on the compressor bypass pipe 17. .

Next, the operation of this system will be explained. When starting the system, the switching valve 4 and the control valves 6 and 10 are closed, and the switching valve 14, the control valve 16, and the on-off valve 18 are opened.
Start 2. The compressed air from the startup compressed air supply device 12 passes through both the compressor 2b and the compressor bypass piping 17, but most of the air passes through the compressor bypass piping 17 because the ventilation resistance on the compressor 2b side is large. The compressed air then reaches the air supply pipe 5, and is then introduced into the turbine 2a via the startup bypass pipe 15 and the system exhaust gas pipe 7. In this configuration, most of the air that exits the startup compressed air supply device 12 bypasses the compressor 2b, so the turbine 2
The ventilation resistance, that is, the pressure loss up to the inlet of the turbine a is small, and therefore, it is possible to give a large starting power to the turbine 2a of the turbo compressor 2 compared to the conventional configuration. That is, in order to start the turbo compressor 2, it is necessary to inject air with a pressure and air volume above a certain level into the turbine 2a, but with this method, a starting compressed air supply device with a smaller capacity than the conventional configuration is used. The turbo compressor 2 can be activated. Once the turbo compressor 2 is started, the compressor 2b tries to start blowing air by rotation, so that the air from the startup compressed air supply device 12 passes through the compressor 2b. At the point when compressor 2b starts blowing air,
When the on-off valve 18 of the compressor bypass piping 17 is closed, the pressure increase is ready. The timing of whether or not the compressor 2b starts blowing air may be determined based on the rotational speed of the turbo compressor 2, or based on the difference between the suction pressure and the discharge pressure of the compressor 2b. After this, the control valve 10 is opened, and at the same time, fuel is introduced from the fuel supply pipe 11 to start combustion in the auxiliary combustor 8. Due to the combustion in the auxiliary combustor 8, the temperature of the gas entering the turbine 2a 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. increases. During this time, the compressed air from the startup compressed air supply device 12 is continuously pushed into the inlet side of the compressor 2b, so that the compressor 2b can secure sufficient air volume with a relatively low compression ratio 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, the switching valve 4 is opened to stop the starting compressed air supply device 12, the switching valve 14 is closed, and the turbo compressor 2 Achieve self-driving condition. The time to stop the starting compressed air supply device 12 is when the outlet pressure of the starting compressed air supply device 12, that is, the suction pressure of the compressor 2b is 0 kg/cm ²
It may also be the point when the pressure drops to around G (atmospheric pressure).
All that is left to do is gradually close the control valve 6 and gradually open the control valve 16 to transfer the air discharged from the compressor 2b to the system 1.
and complete the system startup.

In addition, in the above embodiment, an example was described in which the on-off valve 18 was installed on the compressor bypass piping 17, but a check valve may be used instead of this on-off valve.
have the same effect. An embodiment using a check valve is shown in FIG. In the figure, 19 indicates a check valve,
In this case, the check valve 19 is installed in a direction that prevents backflow from the air supply pipe 5 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 19,
When the compressor 2b starts blowing air,
That is, since the check valve 19 is automatically closed when the discharge pressure of the compressor 2b exceeds the suction pressure, it is no longer necessary to close the on-off valve at this point, which was necessary in the embodiment shown in FIG. .

In addition, the air supply pipe 3 on the inlet side of the compressor 2b
The switching valve 4 on the top may be replaced with a check valve, and the switching valve 14 on the introduction pipe 13 may be omitted.
The same effects as those of the embodiments shown in FIG. 1 and FIG. 2 are achieved respectively.

In the above embodiment, the case where the target is a fuel cell power generation system has been 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 systems using turbo compressors. This embodiment has the same effect as the above embodiment.

〔Effect of the invention〕

As described above, according to the present invention, compressor bypass piping is installed that connects the inlet side piping and outlet side piping of the compressor via a valve, and when the turbo compressor is started, the compressed air supply device for starting Since the turbo compressor is started by passing air through this compressor bypass piping, the turbo compressor can be started easily and stably using a comparatively small capacity starting compressed air supply device. Can be done.

[Brief explanation of drawings]

FIG. 1 is a system diagram showing a turbo compressor system according to one embodiment of the present invention, FIG. 2 is a system diagram showing a turbo compressor system according to another embodiment of the invention, and FIG. 3 is a system diagram showing a conventional turbo compressor system. A system diagram showing the system is shown. 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 an air supply pipe, 7 is a system exhaust gas pipe, 12 is a starting compressed air supply device, 1
7 is a compressor bypass pipe, and 18 and 19 are valves. 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 on the side, compressor bypass piping is installed to connect the inlet side piping and the outlet side piping of the compressor via a valve, Air from the compressed air supply device for startup is guided to the compressor bypass piping when the turbo compressor is started, and a valve of the compressor bypass piping is closed after the turbo compressor is started. turbo compressor system. 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.