JPS608620A - Checking system for leakage of fuel control valve - Google Patents

Abstract

PURPOSE:To reliably detect a leakage if a leak through either of fuel control valves occurs, resulting in sharp improvement of reliability, by a method wherein, when a heat demand signal is generated, the one fuel control valve is opened but the other fuel control valve is held in a closed state, and a motion of checking a leak is alternately effected each time a combustion demand signal arrives. CONSTITUTION:When a heat demand signal arrives, relays K1 and K3 are immediately brought into an operative state, but a relay K2 is brought into an operative state after a given time elapsed. The other fuel control vlave V2 is in a closed state and can detect a leakage of a fuel control valve V2. When a succeeding combustion demand signal (a) arrives, the alternating motion relay K3 is inverted to an OFF-state, a contact K3-1 is switched to the contact K2-1 side, and a contact K3-2 is switched to the contact K1-2 side. Thus, during an on-delay time after the combustion demand signal arrives, the combustion control valve V2 is brough into an opening motion state, but the V1 maintains a closed state, and thereby a leak through a fuel valve V1 can be detected by following the same procedures.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a system for checking for leakage in two fuel control valves that are mutually provided in series in a fuel supply line of a gas combustor or the like.

In order to achieve an improvement in fuel efficiency, two fuel control valves are often connected in series with each other. However, if for some reason one of the fuel control valves fails to close completely and fuel leaks, there is no way to check all of this, and a pseudo-fire check is only performed when both fuel control valves leak. It is possible to detect it by means such as. However, the situation where both fuel control valves leak cannot be resolved even if combustion is stopped by high limit operation or the like, so there is a high risk of an accident occurring.

The present invention provides a fuel control valve checking method that can reliably detect leakage from either of two fuel control valves installed in series, and can prevent risks of accidents such as explosions. It is an object.

Next, an embodiment of the present invention will be described with reference to the drawings. FIG. 1 shows a gas combustor to which the leak check system of the present invention is applied, in which 1 is a burner, and 2 is a fuel control unit that is provided in series with each other for supplying fuel gas to burner 1. The valve 3 is a fire detector that detects a fire in the burner 1. When combustion of the burner 1 is required, the combustion control device 4 simultaneously opens the fuel control valves v1 and V2' to supply all the fuel gas to the burner 1, and also drives an ignition wave # (not shown) to start the burner 1. Make a motion to ignite. Further, the ignition of the burner 1 is detected by the fire detector 3, and the flame relay is activated by the output thereof, thereby entering a normal combustion state. In order to extinguish the burner 1, when there is no longer a combustion request, the fuel control valves v1 and V2 are closed, and the flame relay to the burner 1 is deactivated at this time.

An example of a circuit that drives the fuel control valves Vl and V2''i and checks their leakage is shown in Figure 2.This circuit consists of a relay Kl, an on-delay relay 2, and an on-delay relay that operate in response to a combustion request signal, respectively. There are three alternating relays, and the valves Vl and V2' are controlled by a combination of on/off operations of the contacts of each relay.In other words, relay 1 operates when a combustion request signal is supplied. , the three normally open contacts K1-1, KI-2, and K1-3 are all turned on, and at the same time as the combustion request signal disappears, K1-1
, K1-2°Kl-3'r has the function of turning off. In addition, when the combustion request signal is supplied to the on-delay relay 2, it operates after a predetermined on-delay time, and the two normally open contacts are connected to the 2-1°K2-2 until the combustion request signal is no longer present.
'(i) has the function of turning on and turning off 2-3 to one normally closed contact.Furthermore, the alternating operation relay 3 has the function of turning 3-1 on two contacts every time a combustion request signal arrives. 3-
2 at the same time.

The contacts 1-1 and 2-1 are connected in parallel to one fuel control valve v1, and either one of the contacts 1-1 and 2-1 is selected by the contact 3-1. be done. Also, the contacts 1-2 and 2-2 are connected to the other fuel 1.
They are mutually connected in parallel to the 1it control valve v2, and one of them is selected as a contact point by 3-2.

Further, contacts 1-3 and 2-3 are connected in series with normally open contact PK-1 of the flame relay described above to form an AND circuit, and when the AND condition of this AND circuit is satisfied, the delay operation switch The heater SSH is energized. This delayed action switch is a heater SSM
It operates after a predetermined period of time after the alarm is energized to fully operate the alarm.

Next, the operation will be explained. When the heat request signal arrives, relays 1 and 3 immediately enter the operating state as shown in FIG. 3, but relay 2 is configured to enter the operating state after a predetermined on-delay time has elapsed. Now heat request 4
When number 6 arrives, 3 operates on the relay, and 3- is applied to the contact.
If 1 is in the state shown in Fig. 2 (contact K1-1'i is about to be selected), the relay 1 will also enter the operating state, so the contact 1-1 will not be turned on, and the contact 3-1' will be turned on. 1 Oni 3-2 selects 2-2 for the contact, but 2-2 is selected for the contact.
is off during the predetermined on-delay time, so the other fuel control valve v2 is in a closed state. Since the ignition device (not shown) is configured to operate for a predetermined period of time when the heat request signal arrives, the burner 1 will not ignite unless there is a leak in the fuel control valve v2.The shift flame relay will not operate. Since the first contact FK-1 remains off, the heater SSH is not energized. However, if there is a leak in the fuel control valve v2, burner 1 will ignite and contact FK-1 will turn on, so the normally closed contacts 1-3 and 2, which are inactive during the on-delay period, will become on contacts. 2-3
The heater SSH is energized through t-, and an alarm is issued after a predetermined time. In other words, all leaks from the fuel control valve v2 can be detected.

When this on-delay time has elapsed, relay 2 also enters the operating state, so contact 2-2 is also turned on, and fuel control valve v2 is opened along with fuel control valve v1, and Sihana IK fuel gas is supplied. Since the ignition device is configured to operate for a predetermined time at the end of the on-delay time, the burner 1 ignites and enters a normal combustion state. At this time, the flame relay operates and contact FK-1 turns on, but when relay 2 enters the operating state, contact 2-3 turns off, and heater SSH is not energized. Normal combustion will occur.

When the combustion request signal disappears, 1. is sent to the relay at that point. 2 remains inactive, and the fuel control valves V1 and V2 return to the closed state, thereby stopping combustion.

When the next combustion request signal arrives, the alternating operation relay
is reversed to OFF, and the contact 3-1 is switched to the 2-1 side, and the contact 3-2 is switched to the 1-2 side. Therefore, during the on-delay time after the arrival of the combustion request signal, the fuel control valve v2 is in the open operation state, but the fuel control valve vl
Since the valve is maintained in the closed state, leakage of the fuel control valve v1 can be detected by following the same procedure as described above.

As described above, according to the present invention, when a heat request signal is generated, one fuel control valve opens, but the other fuel control valve is kept closed until a predetermined time elapses, and during this time, one fuel control valve is opened. The operation of checking whether the closed fuel control valve is leaking is performed alternately for each fuel control valve each time a combustion request signal arrives, so that one of the two fuel control valves is checked for leakage. Even if there is a leak, it can be detected reliably, and compared to conventional systems that can only be detected after both leaks, significantly higher safety can be ensured. Furthermore, since there is no need to use expensive sensors such as gas sensors or pressure sensors as a means for detecting leakage from the fuel control valve, the present invention can be implemented at low cost and has high reliability.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing the configuration of a combustor to which the leak check method of the present invention is applied, FIG. 2 is a circuit diagram of a device based on the leak check method applied to the combustor of FIG. 1,
FIG. 3 is a timing chart showing the operation of each part in FIG. 2. DESCRIPTION OF SYMBOLS 1...Burner, 2...Fuel supply line, 3...Fire detector, 4...Combustion control device, Vl, V2...Fuel control valve, K1...Relay, K2... - On-delay relay, K3... Alternate operation relay, FK-1... Flame relay contact, SSH... Heater. Patent applicant Yamatake Honeywell Co., Ltd. Representative Patent Attorney Yoshiharu Matsushita 119

Claims (1)

[Claims] In a method of checking for leakage in two fuel control valves installed in series in a fuel supply line, the two fuel control valves, which open when a combustion request signal is supplied, are By opening one fuel control valve with a delay of a predetermined delay time from the other fuel control valve at the start of a supply signal, it is possible to check for leaks in the closed fuel control valve within this delay time. A fuel control valve leakage check system characterized by checking the presence or absence of a combustion signal and alternately switching all fuel control valves which operate on a delay every time the combustion request signal arrives.