JP2006046775A - Air supply valve control device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an air supply valve control device capable of immediately controlling an air supply valve to a closed state even in case that the air supply valve is in any opening/closing state at the time of tripping a house boiler. <P>SOLUTION: In this air supply valve control device for controlling the opening and closing of the air supply valve for supplying steam generated by the house boiler to the outside, a control for automatically closing the air supply valve from the present state to a full-close state is performed when the air supply valve is not in the full-closed state at the time of tripping the house boiler. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an air supply valve control device that controls an opening / closing operation of an air supply valve that supplies steam generated by an in-house boiler to the outside.

  Generally, in-house boilers are installed in power plants such as thermal power generation. The in-house boiler generates auxiliary steam necessary for starting and stopping plant units (generic name for facilities related to power generation such as boilers, turbines, and generators), and the generated auxiliary steam uses an air supply valve. Devices that require this (for example, devices that degas air contained in water in the condensate system, devices that preheat air to activate the ventilation system, and fuel pipes for heating Supplied to a steam tracing device).

  Normally, a device for controlling the air supply valve is connected to the air supply valve, and automatic opening / closing control of the air supply valve is made possible based on a programmed predetermined sequence control. FIG. 3 is a diagram showing a part of the sequence control performed by the conventional air supply valve control device as a logic circuit.

  In the circuit diagram of FIG. 3, the automatic control logic of the opening operation and closing operation of the air supply valve is shown. First, regarding the opening operation of the air supply valve, it is shown that when the “air supply valve open command” signal is turned ON, the “air supply valve inching open” signal is turned ON via the OR circuit 16, thereby The air valve opens (if it is already fully open, it remains). Further, the circuit 41 composed of the AND circuit 15 and the OR circuit 16 has a condition that the air supply valve is not fully closed (the output signal of the NOT circuit 14 is ON) even when the “air supply valve open command” signal is turned OFF. This is a so-called self-holding circuit that enables the control to continue the opening operation of the air supply valve by controlling the “air supply valve inching open” signal to ON.

  On the other hand, in order to close the air supply valve, all input signals of the AND circuit 11 must be turned on. That is, the “air supply valve fully open” signal is ON, the output signal of the OR circuit 13 is ON (the output signal of the NOT circuit 12 is ON (fuel valve closed) or the “in-house boiler trip” signal is ON), and the output signal of the NOT circuit 14 It is shown that the “air supply valve inching closed” signal is turned on only when is ON (the “air supply valve fully closed” signal is OFF). When this condition is satisfied, the air supply valve can be closed.

  Here, the trip of the in-house boiler refers to an abnormality in the in-house boiler (for example, high pressure, low water level (low circulation), insufficient supply of air, fuel, etc.) A state in which the boiler is automatically stopped. When such a local boiler trips, the air supply valve needs to be closed (fully closed). This is because it is necessary to maintain the in-house boiler in a closed state without supplying the auxiliary steam until the pressure of the auxiliary steam to be supplied satisfies a predetermined condition at the time of starting the in-house boiler.

  However, in the conventional control sequence based on the circuit diagram of FIG. 3, even if the “in-house boiler trip” signal is turned ON, the “air supply valve inching closed” signal is not turned ON unless the air supply valve is fully opened. The air supply valve cannot be closed automatically. That is, in the above conventional control sequence, only the case where the in-house boiler trips during normal operation is assumed, and the automatic closing logic when the air supply valve trips during the opening operation is not incorporated. Conventionally, in such a case, it is necessary to wait until the air supply valve is fully opened, and then close the air supply valve by an operation of a worker or the like (forced signal (air supply valve close command) from the central control room or the like). Had gone.

  However, in such a conventional response, if an error occurs such as an operator forgetting the operation, the in-house boiler may be restarted with the air supply valve open. If it does so, the preparation time (start-up time until auxiliary steam pressure will become fixed pressure) after starting (ignition) until it can supply auxiliary steam will become long, and power expenses, such as a fuel cost, will increase by that much. . In addition, since the air supply valve is open, steam (hot water) at low temperature and low pressure will be supplied to the external device for a while after startup, which may cause damage to the piping, equipment, etc. There is also a risk that the auxiliary steam temperature will rise abnormally excessively.

  The present invention has been made in order to solve the above-described conventional problems. When an in-house boiler trip occurs, the air supply is controlled so that it can be automatically closed even when the air supply valve is in the middle of the opening operation. An object is to provide a valve control device.

  An air supply control device according to the present invention is an apparatus that controls opening and closing of an air supply valve that supplies steam generated by an in-house boiler to the outside, and when the in-house boiler trips, the air supply valve is in a fully closed state. If not, control is performed to automatically close the air supply valve from the current state until it is fully closed.

  According to the above air supply valve control device, when an internal boiler trip occurs, unless the air supply valve is fully closed, control is performed based on the control sequence for closing the air supply valve. Even if the air supply valve is in the process of opening, it immediately switches to the closing operation control, and the air supply valve is closed. Therefore, after the trip, the in-house boiler is not restarted while the air supply valve is open, and safety can be improved.

  As described above, the present invention can immediately control the air supply valve to be in a closed state regardless of the open / closed state of the air supply valve when the internal boiler trips. Costs can be increased and the danger of supplying steam (hot water) with abnormal pressure and abnormal temperature can be eliminated, and safety can be improved.

  Hereinafter, an embodiment of an air supply valve control device according to the present invention will be described with reference to the drawings.

  FIG. 1 is a conceptual diagram of an auxiliary steam supply system including an air supply valve control device according to the present embodiment. In FIG. 1, an in-house boiler 1 is installed at a predetermined location in a power plant, and substitutes steam (auxiliary steam) when starting and stopping the unit, that is, during a period when main steam from the unit boiler is not supplied. It produces | generates and supplies to an air deaeration apparatus, an air preheating apparatus, a steam trace apparatus, etc. via the air supply valve 2. FIG.

  The protection device 3 monitors the state of the in-house boiler 1 (steam pressure, steam level, etc.), and when an abnormality (high pressure, low level, etc.) is detected, the operation of the in-house boiler 1 is stopped (tripped) A trip signal (ON) is output to the air supply valve control device 4.

  The air supply valve control device 4 uses the trip signal, a signal related to the state of the air supply valve 2 and an operation signal from a central control device (not shown) as input parameters to control opening / closing of the air supply valve 2 based on a predetermined control sequence. I do. The control sequence is programmed and stored in a storage device (for example, ROM) (not shown) provided in the air supply valve control device 4. Similarly, the program is read and executed by a processing device (not shown) such as a CPU provided in the device.

  In the air supply valve control device 4 according to the present embodiment, in the control sequence, when the trip signal (ON) is input from the protection device 3, the air supply valve 2 is in the middle of the opening operation (a state where the air supply valve 2 is fully closed and not fully open). Even so, it has a feature in that it has a logic that can be immediately switched to the closing operation.

  Hereinafter, such feature points will be described with reference to FIG.

  FIG. 2 is a diagram showing a part of sequence control performed by the air supply valve control device 4 according to the present embodiment in a logic circuit. FIG. 2 shows the automatic control logic of the opening and closing operations of the air supply valve as in FIG.

  In FIG. 2, 21 and 24 are newly added circuits (logic) that are not present in the conventional circuit (FIG. 3). Further, the circuit 28 is a self-holding circuit corresponding to the circuit 31 of FIG. 3, and a difference from the circuit 31 is that a line indicated by a broken line is newly input to the AND circuit 15. The common parts of the circuit shown in FIG. 4 and the conventional circuit shown in FIG. 3 are denoted by the same reference numerals and description thereof is omitted.

  The circuit 21 includes an AND circuit 22 and an OR circuit 23. The AND circuit 22 is configured to receive an “air supply valve fully open” signal and an “in-house boiler trip” signal. Further, the output signal of the AND circuit 22 and the output signal of the OR circuit 13 are input to the OR circuit 23. The output signal of the OR circuit 23 becomes the input signal of the AND circuit 11.

  By adding the circuit 21, if the output signal of the OR circuit 13 is ON and the output signal of the NOT circuit 14 is ON (not in a fully closed state), the output signal of the AND circuit 11 is turned ON and the OR that inputs it is input. Since the output signal of the circuit 27 is also turned ON, the “air supply valve inching close” signal is turned ON, and the air supply valve can be closed.

  Since the input signal of the OR circuit 13 is the output signal of the NOT circuit 12 and the “in-house boiler trip” signal, when the “in-house boiler trip” signal is turned on by the circuit 21, whether or not the air supply valve is fully opened. Regardless, a control sequence that can immediately control the closing operation is established. The addition of the circuit 21 allows the closing operation control to be performed immediately even when the output signal of the NOT circuit 12 is ON (“fuel valve open” signal OFF), but this does not cause any inconvenience. The reason for this is that when the fuel valve is closed (when combustion is not performed in the in-house boiler 1), auxiliary steam cannot be supplied, so the air supply valve 2 must be closed. is there.

  The circuit 24 includes a NOT circuit 25, an AND circuit 26, and an OR circuit 27, and the “air supply valve fully closed” signal is input to the NOT circuit 25, and the output signal of the NOT circuit 25 and the OR circuit are input to the AND circuit 26. The output signal of the circuit 27 is input, and the output signal of the AND circuit 26 and the output signal of the AND circuit 11 are input to the OR circuit 27.

  The circuit 24 having such a configuration is a so-called control in which once the output signal of the AND circuit 11 is turned ON, control is performed to continue the closing operation until the air supply valve 2 is fully closed even if the output signal is turned OFF thereafter. It has a role as a self-holding circuit. Specifically, for example, it is effective when the boiler trip signal is once turned ON, but is reset (OFF) for some reason before the air supply valve 2 is closed.

  The circuit 28 functions as a self-holding circuit that performs control to continue the opening operation of the air supply valve even when the “air supply valve opening command” signal is turned from ON to OFF, as in the conventional circuit 31 of FIG. The difference from the prior art is that a NOT circuit 29 is added and this output signal is input to the AND circuit 15. With this change, even if the self-holding circuit is functioning (the “air supply valve open command” signal is OFF and the “air supply valve inching open” signal is ON), the output signal of the OR circuit 13 is ON (ie, the fuel valve is closed). (Or trip state), the “air supply valve inching open” signal can be immediately turned OFF. Therefore, switching from the opening operation control of the air supply valve 2 to the closing operation control can be performed smoothly.

  As described above, according to the air supply valve control device of the present embodiment, when the in-house boiler 1 trips in a state where the air supply valve is open, it is possible to automatically control the closing operation of the air supply valve 2. The in-house boiler 1 can be restarted without any trouble after the trip.

  The air supply valve control device according to the present invention is not limited to the above embodiment, and various modifications can be made without departing from the gist of the present invention.

  For example, in the above-described embodiment, the air supply valve control device is shown as an independent device that controls the air supply valve. However, the present invention is not limited to this. For example, the air supply valve control device can also be applied as a function of an in-house boiler control system. It is.

1 is a conceptual diagram of an auxiliary steam supply system according to an embodiment of the present invention. It is a logic circuit diagram of opening and closing control performed by the air supply valve control device according to the same embodiment. It is a logic circuit diagram of the opening / closing control which the conventional air supply valve control apparatus performs.

Explanation of symbols

1 In-house boiler 2 Air supply valve 3 Protection device 4 Air supply valve control device

Claims (1)

A device that controls the opening and closing of an air supply valve that supplies steam generated by the in-house boiler to the outside,
If the air supply valve is not fully closed when the internal boiler trips, the air supply valve is automatically controlled to be closed until it is fully closed from the current state. Air supply valve control device.

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