JPH10141006A - Control device for city gas line energy recovery turbine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To hold a pressure in a spot situated downstream from a turbine at a constant value in all cases of the starting period, the operation period, and the stop period of the turbine, to maintain a generation amount at a maximum, and to prevent the occurrence of overload operation of the turbine, in a system to effect recovery of city gas line energy by an expansion turbine. SOLUTION: An automatic pressure regulating valve for turbine 2 is located in a gas line 4 on the inlet side of an expansion turbine 1 and a bypass line 5 having an automatic pressure regulation valve for bypass 3 is arranged in a state to intercouple the inlet side of the automatic pressure regulation valve for turbine 2 and the exhaust side of an expansion turbine 1. Pressure.flow regulating means 6, 7, and 8 are provided such that through control of opening and closing of the automatic pressure regulation valve for bypass 3 during the starting and the stop of operation of the expansion turbine 1, a pressure regulation means 6 to hold a pressure in a spot situated downstream from a confluent line of a turbine line and a bypass line at a constant value and the automatic pressure regulating valve for turbine 2 are opened and closed so that, during operation of the expansion turbine 1, a flow rate through a turbine line is adjusted to a value approximately equal to a given value in a range not to exceed the given value, and a pressure in a downstream spot is held at a constant value.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a stable gas supply for an energy recovery turbine which is provided in a city gas supply line and is directly expanded using a high-pressure supply gas as a working medium, and is used for cold energy utilization and power generation. It relates to a control device.

[0002]

2. Description of the Related Art A typical prior art of a cold power generation plant related to a turbine installed at a governor station or the like associated with a city gas supply line and directly expanding low-temperature and high-pressure NG which is a raw material of the city gas is disclosed in the prior art. Kaisho 57-1141
No. 39 (first conventional example) and Japanese Utility Model Laid-Open No. 58-136603 (second conventional example). The first conventional example has a configuration in which a bypass pipe via an automatic pressure regulating valve is bypass-connected between an inlet side and an exhaust side of a turbine in order to stabilize NG supply when the turbine is stopped. The automatic pressure regulating valve in the bypass line is controlled by a pressure controller provided downstream of the turbine.

On the other hand, the second conventional example has a configuration in which an automatic pressure regulating valve is installed at the turbine inlet in addition to the automatic pressure regulating valve in the bypass pipe, and only the pressure downstream of the turbine is controlled as a detection signal.

[0004]

In the case of the first prior art, since this is a control means which operates only when the turbine is stopped, when the gas supply amount fluctuates greatly at the time of start-up or operation of the turbine, the control means is provided downstream of the turbine. There is no means for keeping the pressure constant and supplying gas stably.

Further, in the case of the second conventional example, since only the function of controlling the downstream pressure as the sum of the flow rates of the turbine line and the bypass line is constant, it is impossible to control the flow rate of each turbine line. Therefore, control is performed to maintain the power generation amount of the turbine at the maximum, and when the flow rate is too large in the turbine line and the load is overloaded (excessive rotation due to the excessive flow rate), the bypass valve is opened to maintain the predetermined turbine flow rate. It does not have a control means to perform.

SUMMARY OF THE INVENTION The present invention has been made to solve such a problem, and an object of the present invention is to provide a system for recovering city gas line energy using an expansion turbine of this kind. The turbine downstream pressure is kept constant for all cases of operation and shutdown including flow rate fluctuations during start-up and flow rate, and stable supply of gas is maintained, and power generation in the turbine is maintained at the maximum, and An object of the present invention is to improve the operation efficiency and safety by avoiding overload operation of the turbine.

[0007]

The present invention has the following configuration to achieve the above object. That is, according to the present invention, a turbine automatic pressure regulating valve is provided in a pipe connected to an inlet side of an expansion turbine for energy recovery for use in cold heat or power generation installed in a city gas line, and a bypass automatic pressure regulating valve is provided. A bypass line having a pressure valve is provided by connecting the inlet side of the turbine automatic pressure regulating valve to the exhaust side of the expansion turbine, and the bypass automatic pressure regulating valve is controlled to open and close when the expansion turbine is started and stopped. Pressure adjusting means for maintaining the downstream pressure of the merging line of the line and the bypass line constant; and controlling the automatic pressure regulating valve for the turbine so that the flow rate of the turbine line does not exceed a predetermined value during operation of the expansion turbine. Pressure control means for opening and closing so as to approach the value so as to keep the downstream pressure constant. A control device for the energy recovery turbine.

[0008] The present invention also provides a bypass pipe having an automatic pressure regulating valve for bypass, in which a nozzle of an expansion turbine for energy recovery which is installed in a city gas line and used for cooling and power generation is formed as a variable nozzle capable of adjusting a flow rate. While the passage is provided connecting the inlet side and the exhaust side of the expansion turbine, the automatic pressure regulating valve for bypass is controlled to be opened and closed when the expansion turbine is started and stopped, so that the downstream pressure of the merging line of the turbine line and the bypass line is constant. Pressure control means for controlling the variable nozzle to increase or decrease the flow rate of the turbine line during operation of the expansion turbine so as to approach the predetermined value within a range that does not exceed the predetermined value, so that the downstream pressure is constant. And a nozzle adjusting means for maintaining the gas turbine in a city gas line energy recovery turbine.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described below with reference to the accompanying drawings, in which embodiments are shown. FIG. 1 shows a schematic system of a gas supply power generation plant to which an embodiment of the invention described in claim 1 is applied.
This gas supply power plant is provided, for example, in a city gas supply line, and includes an expansion turbine 1 and a gas pipeline 4 connected to an inlet side of the expansion turbine 1 and forming a main part of the turbine line. , A downstream gas line connected to the exhaust side of the expansion turbine 1 and also forming a main part of the turbine line, and a generator 9 axially connected to the expansion turbine 1. The main system is configured.

A control device for controlling the operation of the turbine is provided for the main system. This device comprises a turbine automatic pressure regulating valve 2, a bypass pipe line (bypass line) 5 in which a bypass automatic pressure regulating valve 3 is provided, a pressure gauge 6, a flow meter 7, and a pressure flow controller 8. Made up of The turbine automatic pressure regulating valve 2 is provided in the middle of the gas line 4,
The pressure and flow rate of the gas supplied to the expansion turbine 1 are adjusted. The bypass line 5 is provided connecting the inlet side of the turbine automatic pressure regulating valve 2 and the exhaust side of the expansion turbine 1.
The bypass automatic pressure regulating valve 3 regulates the pressure and flow rate of the gas flowing through the bypass line 5.

A pressure gauge 6 is provided on a merging line connected to the exhaust-side pipe of the expansion turbine 1 and the bypass pipe 5, detects a downstream pressure of the merging line, and opens and closes the automatic pressure regulating valve 3 for bypass. While controlling, the detection signal is transmitted to the pressure flow controller 8. The flow meter 7 detects the gas flow rate in the exhaust-side pipeline of the expansion turbine 1 and transmits a detection signal to the pressure flow controller 8. The pressure flow controller 8 receives the detection signals of the pressure gauge 6 and the flow meter 7 and controls opening and closing of the turbine automatic pressure regulating valve 2.

In the gas supply power plant, the LNG is pressurized and vaporized, and the high-pressure gas (NG) generated by vaporization is directly expanded in the expansion turbine 1 as a working medium. While being stored in a reservoir tank or the like via a merging line, the expansion turbine 1
Is converted into electric energy by the generator 9.

Next, the operation of the control device will be described. When the expansion turbine 1 is started or stopped, the pressure gauge 6 detects an increase and a decrease in the exhaust pressure, and sends a control signal for maintaining a constant downstream pressure of a merging line of the turbine line and the bypass line to a bypass automatic pressure regulating valve. Output to 3.
As a result, the bypass automatic pressure regulating valve 3 opens and closes to adjust the valve opening degree, the bypass flow rate in the bypass line 5 is controlled, the pressure is prevented from increasing and decreasing, and the downstream pressure is kept constant. it can.

On the other hand, when the pressure and the flow rate of the turbine line fluctuate during the operation of the expansion turbine 1, the pressure gauge 6 and the flow meter 7 detect the change in the pressure and the flow rate and merge through the pressure / flow rate controller 8. A control signal for keeping the line pressure and the turbine line flow rate constant is output to the turbine automatic pressure regulating valve 2. In this case, the flow rate of the turbine line is first controlled for the two control elements of the pressure and the flow rate, and the turbine flow rate is controlled so as to maximize the power generation in a flow rate range not exceeding a predetermined value. And the downstream pressure is kept constant by opening and closing the bypass automatic pressure regulating valve 3. That is, the automatic pressure regulating valve for turbine 2 is controlled to open and close so that the flow rate of the turbine line does not exceed the predetermined value and approaches the predetermined value, and the downstream pressure is kept constant by the automatic pressure regulating valve 3 for bypass. And the overload of the turbine 1 can be prevented.

FIG. 2 shows a schematic system of a gas supply power generation plant to which another embodiment of the present invention is applied. In the control device of this gas supply power plant, each member similar to and corresponding to the control device of the embodiment shown in FIG. 1 is denoted by the same reference numeral, and the characteristic portions are omitted here to avoid redundant description. It is described below.

A particular point of attention in the embodiment shown in FIG. 2 is that in the expansion turbine 1, for example, a radial turbine, a nozzle provided around a moving blade is formed as a variable nozzle 10 capable of changing a flow rate. As a mechanism for adjusting the flow rate of the variable nozzle 10, a well-known nozzle operating device 11 that can be operated from outside the turbine casing by an actuator such as an air cylinder or a servomotor, and a nozzle that automatically operates the nozzle operating device 11 And nozzle adjusting means comprising the adjuster 12.
Then, the nozzle adjuster 12 receives the detection signals of the pressure gauge 6 and the flow meter 7 and controls the operation amount such as the stroke and the number of revolutions of the nozzle operating device 11.

Next, the operation of the control device will be described.
When the expansion turbine 1 is started or stopped, the pressure gauge 6 detects an increase and a decrease in the exhaust pressure, and sends a control signal for maintaining a constant downstream pressure of a merging line of the turbine line and the bypass line to a bypass automatic pressure regulating valve. Output to 3. As a result, the automatic pressure regulating valve for bypass 3 opens and closes to adjust the valve opening, the bypass flow rate of the bypass line 5 is controlled, the pressure drop is prevented, and the downstream pressure can be kept constant.

On the other hand, when the pressure and flow rate of the turbine line fluctuate during the operation of the expansion turbine 1, the pressure gauge 6 and the flow meter 7 detect changes in the pressure and flow rate, and
A control signal for keeping the pressure of the merging line and the flow rate of the turbine line constant through 2 is output to the nozzle operating device 11. In this case, the flow rate of the turbine line is first controlled for the two control elements of the pressure and the flow rate, and the turbine flow rate is controlled so as to maximize the power generation in a flow rate range not exceeding a predetermined value. And the downstream pressure is kept constant by opening and closing the bypass automatic pressure regulating valve 3. That is, by controlling the opening and closing of the variable nozzle 10 so that the flow rate of the turbine line does not exceed the predetermined value and approaches the predetermined value, the downstream pressure can be kept constant. Turbine 1
Overload can be prevented.

[0019]

The present invention is embodied in the form described above and has the following effects.

According to the first aspect of the present invention, the downstream pressure of the turbine is kept constant under all of the starting, operating, and stopping conditions, and the maximum amount of power generation and the amount of cold energy corresponding to the conditions during operation are maintained. Can be achieved. Further, since the turbine is operated in a range not exceeding the predetermined flow rate, stable operation is ensured without overloading (overflow) of the turbine.

[0021] In the invention of the second aspect of the present invention, a larger turbine head can be obtained during operation than the effect of the first aspect of the invention, so that a larger amount of power generation and cooling can be obtained. The effect is achieved.

[Brief description of the drawings]

FIG. 1 is a schematic system diagram of a gas supply power plant according to one embodiment of the present invention.

FIG. 2 is a schematic system diagram of a gas supply power plant according to another embodiment of the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Expansion turbine, 2 ... Automatic pressure regulating valve for turbine, 3 ... Automatic pressure regulating valve for bypass, 4 ... Gas line, 5 ... Bypass line, 6 ... Pressure gauge, 7 ... Flow meter, 8 ... Pressure flow controller, 9: generator, 10: variable nozzle, 11: nozzle operating device, 12: nozzle adjusting device,

Claims (2)

[Claims] An automatic pressure control valve for a turbine is provided in a pipe connected to an inlet side of an expansion turbine for energy recovery for use in cold energy or power generation installed in a city gas line, and an automatic pressure control valve for a bypass. A bypass line connecting the inlet side of the turbine automatic pressure regulating valve and the exhaust side of the expansion turbine is provided, while the bypass automatic pressure regulating valve is opened / closed when the expansion turbine is started / stopped, and a turbine line is provided. Pressure regulating means for maintaining a constant downstream pressure of the merging line of the bypass line and the bypass line; and setting the turbine automatic pressure regulating valve to a predetermined value within a range in which the flow rate of the turbine line does not exceed the predetermined value during operation of the expansion turbine. And a pressure flow control means for controlling the opening and closing so as to approach the pressure so as to keep the downstream pressure constant. Energy recovery turbine control device. 2. A nozzle of an expansion turbine for energy recovery which is installed in a city gas line and used for cold energy use or power generation is formed as a variable nozzle capable of adjusting a flow rate, and a bypass pipe having an automatic pressure regulating valve for bypass is expanded. While the inlet side and the exhaust side of the turbine are connected and provided, the automatic pressure regulating valve for bypass is controlled to be opened and closed when the expansion turbine is started and stopped, so that the downstream pressure of the merging line of the turbine line and the bypass line is kept constant. Pressure control means for controlling the variable nozzle to increase or decrease the flow rate of the turbine line during operation of the expansion turbine so as to approach the predetermined value within a range not exceeding the predetermined value, so that the downstream pressure is maintained constant. A control device for a city gas line energy recovery turbine, characterized by comprising a nozzle adjusting means.