Power plants – Motive fluid energized by externally applied heat – Process of power production or system operation
Reexamination Certificate
2001-12-10
2002-10-01
Nguyen, Hoang (Department: 3748)
Power plants
Motive fluid energized by externally applied heat
Process of power production or system operation
C060S670000, C415S017000
Reexamination Certificate
active
06457313
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a pressure and flow control apparatus, and a plant system using the same. More particularly, the present invention relates to a pressure and flow control apparatus in which a pressure control valve is connected with another control valve in series.
2. Description of the Related Art
To control a pressure and a physical quantity of fluid at the same time, a pressure control valve and anther control valve are connected in series.
FIG. 1
shows a conventional pressure and flow control apparatus. Referring to
FIG. 1
, the conventional pressure and flow control apparatus is composed of a pressure control valve
101
and a flow rate control valve
102
. A pipe
103
is connected with the input side of the pressure control valve
101
. A pipe
104
is connected between the output side of the pressure control valve
101
and the input side of the flow rate control valve
102
. The output side of the flow rate control valve
102
is connected with a pipe
105
. The fluid is introduced into the pipe
103
, and is led to the pipe
104
through the pressure control valve
101
. Then, the fluid in the pipe
104
is led to the pipe
105
through the flow rate control valve
102
.
The opening degree of the pressure control valve
101
is controlled by a pressure gauge
106
, a difference unit
107
and a pressure control unit
108
. The pressure gauge
106
measures the pressure X
P
in the pipe
104
. The difference unit
107
calculates the difference between the measured pressure X
P
and a reference pressure R
P
to obtain a deviation E
P
. The degree U
P
of the pressure control valve
101
based on the deviation E
P
. The opening degree of the pressure control valve
101
is set to the determined opening degree U
P
. As a result, the pressure X
P
of the pipe
104
is controlled to be coincident with the reference pressure R
P
.
Also, the opening degree of the flow control valve
102
is controlled by a flowmeter Fx
109
, a difference unit
111
, and a flow control unit
112
. The flowmeter FX
109
measures the flow rate X
F
of the fluid flowing through the pipe
105
. The difference unit
111
calculates a difference between the measured flow rate X
F
and a reference flow rate R
F
to obtain a deviation E
F
. The flow control unit
112
determines the opening degree U
F
of the flow control valve
102
based on the deviation E
F
. The opening degree of the flow control valve
102
is set to the determined opening degree U
F
. As a result, the flow rate X
F
of the fluid flowing through the pipe
105
is controlled to be coincident with the reference flow rate R
F
.
In the above-mentioned pressure and flow control apparatus, the opening degree of the flow control valve
102
has an influence on the pressure XP of the pipe
104
which depends on the opening degree of the pressure control valve
101
. Therefore, it is desirable that the pressure XP of the pipe
104
is controlled, considering such an influence.
Especially, when the opening degree of the flow control valve
102
is small, the pressure control valve
101
often repeats a switching operation between a small opened state and a full closed state. The repetition causes the damage and abrasion of a valve sheet of the pressure control valve
101
. Therefore, it is desirable that the repetition of the switching operation is not carried out in the pressure control valve
101
, even if the opening degree of the flow control valve
102
is small.
In conjunction with the above description, a fuel flow rate control apparatus for a turbine is disclosed in Japanese Laid Open Patent application (JP-A-Heisei 7-54672). In this reference, a fuel-adjusting pipe is connected to a fuel supply system and has a closed portion at one end and a fuel-blowing hole on a side portion. A casing is provided around the fuel-adjusting pipe and connected with a fuel consuming system. A flap valve is provided near the fuel-blowing hole to be movable in a longitudinal direction of the fuel-adjusting pipe for setting an opening quantity of the fuel-blowing hole. A position sensor detects the position of the flap valve. A torque motor is connected to the position sensor and the flap valve and drives the flap valve based on a fuel instruction value and position detection data by the position sensor.
SUMMARY OF THE INVENTION
Therefore, an object of the present invention is to provide a pressure and flow control apparatus in which a pressure control valve is connected to another control valve in series, and the opening degree of the pressure control valve is controlled considering the opening degree of the other control valve.
Another object of the present invention is to provide a pressure and flow control apparatus in which a pressure control valve is connected to another control valve in series, and the pressure control valve does not repeat a switching operation between a small open state and a full close state even if the opening degree of the other control valve is small.
Still another object of the present invention is to provide a pressure and flow control apparatus in which a pressure control valve is connected to another control valve in series, and a damage and abrasion of a valve sheet of the pressure control valve can be prevented.
Yet still another object of the present invention is to provide a plant system having any of the above pressure and flow control apparatuses.
In an aspect of the present, a pressure and flow control apparatus includes first to third pipes, fluid being supplied to the first pipe and outputted from the third pipe, a pressure control valve, a control valve, and a control unit. The pressure control valve is provided between the first and second pipes and opened or closed based on a first opening degree to control flow of the fluid from the second pipe to the third pipe. The control valve is provided between the second and third pipes and opened or closed based on a second opening degree to control flow of the fluid from the first pipe to the second pipe. The control unit determines the first opening degree, and determines the second opening degree based on the first opening degree and a pressure in the second pipe.
Here, the control unit preferably determines the first opening degree based on a physical parameter. In this case, the control unit may include a detecting unit provided for the third pipe to detect the physical parameter. Otherwise, the control unit may include a detecting unit provided for an output of a unit which operates using the fluid outputted from the third pipe, to detect the physical parameter. The physical parameter is one of temperature and flow rate.
Also, the control unit may determine the first opening degree based on the physical parameter and a first reference value.
Also, the control unit may include a pressure-detecting unit which detects the pressure in the second pipe.
Also, the control unit may determine the second opening degree such that the second pressure control valve is always opened as far as the control valve is opened.
In another aspect of the present invention, a pressure and flow control apparatus includes first to third pipes, fluid being supplied to the first pipe and outputted from the third pipe, a pressure control valve, a control valve and a control unit. The pressure control valve is provided between the first and second pipes and opened or closed based on a first opening degree to control flow of the fluid from the second pipe to the third pipe. The control valve is provided between the second and third pipes and opened or closed based on a second opening degree to control flow of the fluid from the first pipe to the second pipe. The control unit determines the first opening degree, determines a first temporary opening degree based on the first opening degree, determines a second temporary opening degree based on a pressure in the second pipe, and determines the second opening degree based on the first and second temporary opening degrees.
Here, the control unit may include a function
Mitsubishi Heavy Industries Ltd.
Nguyen Hoang
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