JPH034736B2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a method for controlling a turbo compressor system, and particularly to a turbo compressor system for controlling the pressure of air discharged from a compressor of a turbo compressor. The present invention relates to a control method.

[Conventional technology]

A conventional method of controlling a turbo compressor system will be explained with reference to FIG. 3, taking a method of controlling a fuel cell power generation system as an example. In the figure, a load section 1 that requires compressed air and discharges exhaust gas,
A turbo compressor 2 consisting of a turbine 2a and a compressor 2b, a variable nozzle 2c at the gas inlet of the turbine 2a, an air supply pipe 3 that guides compressed air discharged from the compressor 2b to a load section 1, and an exhaust gas from the load section 1. system exhaust gas piping 4 that guides air to the turbine 2a, a pressure detector 5 installed in the middle of the air supply piping 3, and a variable nozzle 2c based on the compressor discharge air pressure detected by the pressure detector 5.
a pressure controller 6 that feedback-controls the compressor discharge air pressure to a predetermined value by manipulating the opening degree of the compressor; and a pressure setting value 7 for the pressure controller 6.
In the system, the compressor discharge air pressure is determined by the balance between the air flow rate supplied to the load section 1 through the air supply pipe 3 and the air flow rate discharged from the compressor 2b. If the compressor discharge air pressure is constant, the compressor discharge air flow rate is approximately proportional to the power of the turbine 2a, and if the turbine inlet gas pressure is constant, the turbine power is determined by the square root of the absolute temperature of the turbine inlet gas and the variable nozzle 2c. Proportionate the opening. Therefore, for example, if the compressor discharge air pressure becomes lower than a predetermined value, this means that the compressor discharge air pressure is insufficient with respect to the air flow rate supplied to the load section 1, and the variable nozzle 2
The compressor discharge air pressure can be increased by increasing the opening degree of c and using turbine power to increase the compressor discharge air pressure. Based on this principle, the pressure controller 6 feedback-controls the compressor discharge air pressure to the set value 7 by manipulating the opening degree of the variable nozzle 2c based on the compressor discharge air pressure detected by the pressure detector 5.

Here, the compressor discharge air pressure is set to 7.
If the variable nozzle opening degree is reduced too much when the variable nozzle opening is in the vicinity, the turbine power will be too insufficient and the compressor 2b will not be able to compress the air, which may cause a surging phenomenon, which is a type of backflow phenomenon.

[Problem that the invention seeks to solve]

In the conventional turbo compressor system control method as described above, for example, when the compressor discharge air pressure becomes larger than the set value 7, the pressure controller 6 reduces the opening degree of the variable nozzle 2c to control the compressor discharge. Although attempts are made to lower the air pressure, the decrease in the compressor discharge air pressure is delayed due to the piping volume on the compressor discharge side compared to the variable nozzle opening operation, so the compressor discharge air pressure cannot be kept constant. The problem was that it could not be maintained.

The present invention has been made to solve the above-mentioned problems, and an object of the present invention is to provide a control method for a turbo compressor system that can always maintain compressor discharge air pressure within a predetermined value or within a predetermined range.

[Means for solving problems]

A control method for a turbo compressor system according to the present invention includes a first compressor discharge system that feedback-controls compressor discharge air pressure to a set value by operating a variable nozzle opening based on a detected value and a set value of the compressor discharge air pressure. Along with the air pressure control system, the second compressor discharge air pressure is controlled to feed back the compressor discharge air pressure to a set value by manipulating the opening degree of an atmosphere release control valve installed in the middle of the atmosphere release pipe branched from the air supply pipe. The pressure setting value of the second compressor discharge air pressure control system was set slightly higher than that of the first compressor discharge air pressure control system within a range that is not abnormal.

[Effect]

In this invention, if the compressor discharge air pressure is lower than the set value (first set value) to the first compressor discharge air pressure control system, the first compressor discharge air pressure control system controls the variable nozzle opening. The second compressor discharge air pressure control system, which is given a second set value that is higher than the first set value, decreases or fully closes the opening of the atmospheric release control valve, and Try to increase the discharge air pressure. After the opening of the atmospheric release control valve becomes fully closed, the second compressor discharge air pressure control system eliminates the control allowance, but the first compressor discharge air pressure control system works effectively and controls the compressor discharge air pressure. control to the first set value.

If the compressor discharge air pressure is higher than the second set value, it is naturally higher than the first set value, and the first compressor discharge air pressure control system reduces or minimizes the variable nozzle opening, and the second compressor discharge air pressure control system reduces or minimizes the variable nozzle opening. The discharge air pressure control system attempts to reduce the compressor discharge air pressure by increasing or fully opening the atmospheric release control valve. Note that the reason why the variable nozzle opening does not become smaller than the minimum opening is due to the action of the limiter calculation means. After the variable nozzle opening reaches the minimum opening, the first compressor discharge air pressure control system eliminates the control allowance, but the second compressor discharge air pressure control system works effectively and increases the compressor discharge air pressure. control to the second set value.

If the compressor discharge air pressure is higher than the first set value but lower than the second set value, the first compressor discharge air pressure control system reduces or minimizes the variable nozzle opening to reduce the compressor discharge air pressure. The second compressor discharge air pressure control system attempts to increase the compressor discharge air pressure by decreasing or fully closing the opening of the atmospheric release control valve. At this time, the variable nozzle opening may temporarily become minimum and the atmospheric release control valve may become fully closed, eliminating control allowance for both the first and second compressor discharge air pressure control systems. , the compressor discharge air pressure is between the first and second setpoints.

[Embodiments of the invention]

An embodiment of the present invention will be described below with reference to FIG. In FIG. 1, the same or corresponding parts as those shown in FIG. 3 are given the same reference numerals, and the explanation thereof will be omitted.

In FIG. 1, a pressure controller 6 which is a first compressor discharge air pressure control system, a pressure melt setting value (first setting value) 7 for the pressure controller 6,
Atmospheric release piping 8 branched from air supply piping 3 that leads compressed air from compressor 2b to load section 1;
An atmosphere release control valve 9 is located in the middle of the atmosphere release pipe 8 and can adjust the amount of compressed air released to the outside (to the atmosphere, etc.) through the atmosphere release pipe 8, and a pressure controller 10 is a second compressor discharge air pressure control system. , the pressure setting value (second setting value) 11 to the pressure controller 10, and the opening degree command of the variable nozzle 2c that is the operation target of the pressure controller 6. A limiter calculator 12 and the like for indicating a lower limit value are arranged and connected. In addition, the second setting value 11
is set slightly higher than the first set value 7.

Next, the control method will be explained. A pressure controller 6, which is a first compressor discharge air pressure control system, operates the opening degree of the variable nozzle 2c based on the compressor discharge air pressure detected by the pressure detector 5 and the first set value 7, and controls the opening degree of the variable nozzle 2c, for example. If the compressor discharge air pressure is lower than the first set value 7, the variable nozzle opening degree is increased to increase the turbine power, and the air flow rate discharged from the compressor 2b is increased to try to increase the compressor discharge air pressure. As a result, the compressor discharge air pressure is feedback-controlled to the first set value 7. The limiter operator 12 functions to prevent the variable nozzle opening, which is the object of operation of the pressure controller 6, from deviating from the predetermined minimum and maximum opening ranges. The operation value for the degree is guaranteed to be greater than or equal to the minimum degree of opening and less than or equal to the maximum degree of opening.

The second set value 1 is slightly higher than the first set value 7.
The pressure controller 10, which is a second compressor discharge air pressure control system given the value 1, controls the opening of the atmospheric release control valve 9 according to the compressor discharge air pressure detected by the pressure detector 5 and the second set value 11. For example, if the compressor discharge air pressure is higher than the second set value 11, the opening degree of the atmosphere release control valve 9 is increased and the amount of compressed air is released to the outside through the atmosphere release pipe 8. The compressor discharge air pressure is feedback-controlled to the second set value 11 by increasing the compressor discharge air pressure and attempting to decrease the compressor discharge air pressure.

As a result of the above, for example, if the compressor discharge air pressure is lower than the first set value 7, the pressure controller 6 increases or maximizes the opening degree of the variable nozzle 2c, and naturally the compressor discharge air pressure is set to the second set value. 11, the pressure controller 10 attempts to increase the compressor discharge air pressure by decreasing or fully closing the atmospheric release control valve 9. When the atmospheric release control valve 9 is fully closed, the pressure controller 10 eliminates the control allowance, but the pressure controller 6 works effectively and the compressor discharge air pressure is controlled to the first set value 7.

If the compressor discharge air pressure is higher than the second setting 11, it is naturally higher than the first setting 7,
The pressure controller 6 reduces or minimizes the opening degree of the variable nozzle 2c, and also controls the pressure controller 1.
0 increases or fully opens the atmospheric release control valve 9 in an attempt to lower the compressor discharge air pressure. When the opening degree of the variable nozzle 2c becomes the minimum, the pressure controller 6 eliminates the control allowance, but the pressure controller 10 works effectively and the compressor discharge air pressure is controlled to the second set value 11.

If the compressor discharge air pressure is higher than the first set value 7 but lower than the second set value 11,
The pressure controller 6 attempts to lower the compressor discharge air pressure to the first set value 7 by reducing or minimizing the opening degree of the variable nozzle 2c, and the pressure controller 10 reduces the opening degree of the atmospheric release control valve 9 or completely closes it. to lower the compressor discharge air pressure to the second set value 11. At this time, if the opening degree of the variable nozzle 2c becomes the minimum and the atmospheric release control valve 9 is fully closed, the control allowance for both the pressure controllers 6 and 10 is eliminated, but the compressor discharge air pressure remains at the first set value 7. It is between the second setting value 11 and does not indicate an abnormal value, so there is no problem.

On the other hand, as a measure to prevent the surging phenomenon, if a programmable limiter function is provided for the variable nozzle opening or measures are taken to mechanically narrow the movable range of the variable nozzle, for example, the compressor discharge air pressure can be set. If the variable nozzle opening reaches the lower limit when the value is higher than 7, the pressure controller 6 loses control margin after that, causing a problem that the compressor discharge air pressure cannot be actively controlled. However, in the above embodiment, Limiter calculator 12
As a result, the opening degree of the variable nozzle 2c is kept within the upper and lower limits, thereby making it possible to prevent the surging phenomenon from occurring.

Although the above embodiment describes only the control of the compressor discharge air pressure, the turbine inlet gas pressure, which has a large influence on the turbine power, is controlled to maintain the turbine inlet gas pressure at a predetermined value or within a predetermined range. If the turbine power is stabilized in this manner, the compressor discharge air pressure will be more effectively controlled to a predetermined value. As another embodiment, a method for controlling the turbine inlet gas pressure will be described with reference to FIG.
One is that an auxiliary combustion furnace 24 is provided in the middle of the system exhaust gas pipe 4, and the amount of auxiliary combustion in the auxiliary combustion furnace 24, in other words, the flow rate of air for auxiliary combustion, is determined based on the turbine inlet gas pressure detected by the pressure detector 22 and a set value. Alternatively, the pressure controller 25 can feed back the turbine inlet gas pressure to the set value by manipulating the fuel flow rate for auxiliary combustion. A control valve 21 is provided, and a pressure controller 23 operates the opening degree of the turbine bypass control valve 21 based on the turbine inlet gas pressure detected by a pressure detector 22 and a set value to feedback control the turbine inlet gas pressure to the set value. or a method in which the pressure setting value for the pressure controller 23 is set slightly higher than the pressure setting value for the pressure controller 25 by combining the above two methods.

Further, in the above embodiment, the limiter calculator 12 is provided outside the pressure controller 6 which is the first compressor discharge air pressure control system, but the pressure controller 6 may have the same function as the limiter calculator 12. good.

〔Effect of the invention〕

As is clear from the above description, this invention
In addition to the first compressor discharge air pressure control system that operates the variable nozzle opening of the turbine, there is a second compressor discharge air pressure control system that sets the compression setting value to be slightly higher than the first compressor discharge air pressure control system. Since the opening of the atmospheric release control valve is controlled using the system, the compressor discharge air pressure can always be maintained at a predetermined value or within a predetermined range over a wide range of loads, regardless of whether the load is fluctuating or during steady operation. effective.

[Brief explanation of drawings]

Fig. 1 is a circuit diagram for explaining one embodiment of the present invention, Fig. 2 is a circuit diagram for explaining another embodiment, and Fig. 3 is a circuit diagram for explaining a conventional turbo compressor system control method. FIG. 1... Load section, 2... Turbo compressor, 2a...
Turbine, 2b... Compressor, 2c... Variable nozzle, 3... Air supply piping, 5... Pressure detector, 6... First compressor discharge air pressure controller, 8... Atmospheric release piping, 9... Atmosphere Open control valve, 10...second compressor discharge air pressure controller, 12...limiter computing unit. In each figure, the same reference numerals indicate the same or equivalent parts.

Claims (1)

[Scope of Claims] 1. For a load section that requires air and generates exhaust gas, a turbine driven by the exhaust gas from the load section, a variable nozzle provided at the inlet of the turbine, and the turbine directly coaxially connected to
A turbo compressor consisting of a compressor that compresses and supplies the air necessary for the load section, and a turbo compressor that is installed in the middle of an atmosphere release pipe branched from an air supply pipe that leads compressed air from the compressor to the load section. an atmosphere release control valve that can adjust the amount of compressed air released to the outside through the compressor; By controlling the opening degree of the variable nozzle based on the compressor discharge air pressure detected by a pressure detector installed in the middle of the piping, the compressor discharge air pressure is feedback-controlled to the set value. A second compressor discharge air pressure control system, which has a pressure setting value slightly higher than that of the first compressor discharge air pressure control system, controls the compressor discharge air pressure to the set value by controlling the opening degree of the atmospheric release control valve. How to control a turbo compressor system. 2. An upper limit and a lower limit are set for the opening degree of the variable nozzle to be operated by the first compressor discharge air pressure control system, and a limiter calculation means instructs the upper limit when it is above the upper limit, and the lower limit when it is below the lower limit. A method for controlling a turbo compressor system according to claim 1. 3. The method of controlling a turbo compressor system according to claim 1, wherein the load section is a fuel cell power generation system that uses compressed air for fuel cell reaction and reformer combustion.