JPS60232419A - Gas combustion controlling apparatus - Google Patents

Abstract

PURPOSE:To avoid the deviation from the stable combustion zone of a burner even in case where an unusual condition has broken out by arranging plural numbers of differential pressure sensor in parallel to the differential sensor and disposing of the output of these differential pressure by the adding circuit. CONSTITUTION:Suppose the pressure receiving part of a differential sensor 11 has broken, the pressure difference is about to be produced between point (a) and point (d) momentarily, but one hand, because the output signal of the second differential pressure sensor 11A has been added with the output signal of the sensor 11 of the broken side at the adding circuit 16, the sensor 11A regulates so that the pressure difference between point (a) and point (d) becomes zero. That is, the pressure difference of P1-P4 is about to be produced at point (a) and point (d) owing to the sensor 11, but, contrary to this, the pressure difference P1-P4 comes to be produced at the differential pressure sensor 11, and the sensor 11A comes to control the gas proportional control valve 6 so that this pressure difference becomes zero, the pressure control P1=P4, accordingly, P1=P2=P3=P4 is realized at all times.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a control device for a waste combustion device using a pressure equalization control method.

Conventional configuration and its problems A block diagram of a conventional gas combustion control device is shown in FIG.

Combustion air disposed in the air side passage 1 and sent out from the blower 2 passes through the air side throttle 3 and is guided to the mixing section 4. On the other hand, the combustion gas is similarly led to the mixing section 4 through a gas proportional control valve 6 and a gas-side throttle 7 disposed in the gas-side passage 5, and is supplied to the burner 8 as a homogeneous mixed gas. Ru.

A heat exchanger 10 in which a temperature detector 9 is disposed is provided above the burner 8 . Further, a differential pressure sensor 11 is provided which includes a built-in pressure receiving section 11A that detects the pressure difference between the upstream side of the air side throttle 3 and the upstream side of the gas side throttle 7.

The signal from the temperature detector 9 is compared with the signal from the temperature setting device 12, and processed as a deviation signal by the rotation speed control circuit 13 to control the blower 2. On the other hand, the signal from the differential pressure sensor 11 passes through a differential pressure sensor detection circuit 14 and an air-fuel ratio adjustment circuit 15 to control the gas proportional control valve 6.

In this configuration, when there is a change in temperature setting or a change in load due to a change in water volume, the rotation speed of the blower is controlled. In the pressure equalization control method, the upstream pressure P1 of the air side throttle 3,
The upstream pressure P4 of the gas side throttle 7 is controlled so that Pl=P4 at all times.

That is, even if there is a change in Pl, the gas proportional control valve 6 is controlled based on the signal from the differential pressure sensor 11 in response to the change, so that the pressures of Pl and P4 are always equalized.

However, for example, the pressure receiving part of the differential pressure sensor 11 for pressure equalization control, which is used for household combustion equipment, etc., is composed of a thin rubber diaphragm in order to improve the sensor sensitivity. - If this diaphragm (generally used nitrile rubber NBR is known to be gradually degraded by trace amounts of ozone 03 in the atmosphere) is torn during combustion, in many cases, There was a tendency to deviate from the stable combustion range of the gas. The details will be explained below using FIGS. 1, 2, and 3.

If a diaphragm rupture occurs in the differential pressure sensor 11 during combustion, the pressure is Passing from conduit C to d, waste side passage 5
Air flows into the point (point d in Figure 1). In such a state, as is clear from FIG.
A pressure difference occurs between the pressure at point and the pressure at point d, that is, between Pl and P4. Although the differential pressure sensor 11 is controlled so that there is no differential pressure (P2=P3), in reality, pressure is guided from the pressure port of the differential pressure sensor 11 to each of the air and gas passages. This is because there are pressure conduits a glass and pressure conduits C to d for this purpose, and therefore there is an associated pressure loss as the air flows from point a to point d.

Next, the combustion characteristics of the burner 8 in such a case will be explained using FIG. 2. The horizontal axis shows the input amount 1 of the burner 8, the vertical axis shows the excess air ratio m, and (1) and (2) represent the upper and lower limits of stable combustion of the burner 8.

The cases shown by broken lines (A) to (B) indicate a normal state in which the excess air ratio m remains approximately constant even if the combustion amount is varied, and there is no diaphragm breakage.

If the tire flam breaks during combustion, it depends on the size of the tear, but while it is small, the solid line from (Y) to (B) indicates that it is in the stable combustion range, or as it gets larger, ( d) to (b), (e) to (b), completely deviating from the stable combustion upper limit value. However, considering the worst case scenario, there were some points that could not be said to be sufficient from a safety perspective.

Purpose of the Invention The present invention solves such conventional problems, and even in the unlikely event that a tear occurs in the pressure receiving part of the differential pressure sensor during combustion, the burner will deviate from the stable combustion range. The purpose is to ensure that there are no

Structure of the Invention The present invention is a gas combustion control device using a pressure equalization control method in which a conventional differential pressure sensor is installed, and a plurality of differential pressure sensors are newly installed in parallel with the conventional differential pressure sensor, and these differential pressure sensors are It is configured so that the output of the pressure sensor is processed by an adding circuit.

This configuration has the effect of ensuring safety with sufficient reliability even in the unlikely event that the pressure-receiving parts of the 11 differential pressure sensors break (I think it is unlikely that two or more will break at the same time). .

DESCRIPTION OF EMBODIMENTS An embodiment of the present invention will be described below with reference to FIGS. 4, 5, and 6.

Components that are the same as those in FIGS. 1, 2, and 3 are given the same numbers and their explanations will be omitted.

11A is a second differential pressure sensor arranged in parallel with the differential pressure sensor 11, 11B is a pressure receiving part, and 14A is the second differential pressure sensor 1.
1A differential pressure sensor detection circuit 16 is an addition circuit that adds the output signals of the differential pressure sensor 11 and the second differential pressure sensor 11A.

In the above configuration, if there is no tear in the pressure receiving part (diaphragm) of either the differential pressure sensor 11 or the second differential pressure sensor 11A, it is the same as the conventional one.

Now, if a rupture occurs in the pressure receiving part of one of the differential pressure sensors during steady combustion, if the pressure receiving part of the differential pressure sensor 11 breaks, the difference between point a and point d in FIG. However, on the other hand, since the output signal of the second differential pressure sensor 1 i''A is added to the output signal of the differential pressure sensor 11 that has failed in the adding circuit 16, This second differential pressure sensor 11A controls the pressure difference between point a and point d to be zero.

That is, for the differential pressure sensor 11, pl-
A pressure difference of p4 is about to occur, but on the contrary, a pressure difference of pl-p4 is generated in the second differential pressure sensor 11A.
Therefore, the second differential pressure sensor 11A controls the gas proportional control valve 6 so that this pressure difference becomes zero.
In the end, as shown in Fig. 6, the pressure control in the pressure equalization control method is P1=P4.Therefore, Pl=P2=P3=P4
will always hold true.

Note that when the pressure receiving part is not torn, the pressures at point a and point b are equal (P1=P2), and the pressures at point 0 and point d are also equal. (P3=P4) Above, we have explained the case of all-primary burner without secondary air system.
The same applies to Bunsen burners with secondary air systems.

Effects of the Invention As described above, the gas combustion control device of the present invention has a configuration in which a plurality of differential pressure sensors are arranged, and each signal of the differential pressure sensors is processed by an adding circuit to perform pressure equalization control. As a result, there is at least one differential pressure sensor pressure-receiving part that will not be torn during combustion, and even if the other ones should be torn, its safety can be sufficiently ensured and guaranteed.

[Brief explanation of the drawing]

Figure 1 is a block diagram of a conventional gas combustion control device, Figures 2 and 3 are explanatory diagrams of characteristics when the conventional device is abnormal,
FIG. 4 is a block diagram of the gas combustion control device of the present invention, and FIG.
6 and 6 are explanatory diagrams of control characteristics of the device. 1...Air side passage, 2...Blower, 3
...Air side throttle, 4...Mixing section, 5...
...Gas side passage, 6...Gas proportional control valve,
7... Gas side throttle, 8... Burner, 9...
... Temperature detector, 10 ... Heat exchanger, 11.
...Differential pressure sensor, 11A...Second differential pressure sensor, 11B...Pressure receiving part, 12...Temperature setter, 13...Rotation speed control Circuit, 14...
・Differential pressure sensor detection circuit, 14A...Second differential pressure sensor detection circuit, 15...Air space ratio adjustment circuit, 16
...Addition circuit. Name of agent: Patent attorney Toshio Nakao (1st person)
Figure/614 Figure 2 7-> Figure 3 M/7 Fortune-telling, → Figure 10

Claims (3)

[Claims] (1) A blower and an air-side throttle are installed in the air-side passage, and a gas proportional control valve and a gas-side throttle are installed in the gas-side passage, each of which is guided to the mixing section and burned in a burner. A heat exchanger and a temperature detector are provided nearby, and a rotation speed control circuit is provided to control the blower based on the deviation signal between the output signal of the temperature sensor and the temperature setting device, and the air-side throttle upstream and A plurality of differential pressure sensors are arranged to detect the pressure difference with the upstream side of the gas side throttle, and each signal of the differential pressure sensor is sent to a differential pressure sensor detection circuit and the output of the plurality of differential pressure sensors. It is composed of an addition circuit that performs addition processing and an air-fuel ratio adjustment circuit that controls the gas proportional control valve, and when at least one pressure receiving part of the differential pressure sensor is broken, the gas proportional control is performed using another differential pressure sensor. A gas combustion control device configured to control a valve. (2) The gas combustion control device according to claim 1, wherein the mixing section has a venturi tube shape. (3) The gas combustion control device according to claim 1, which comprises two differential pressure sensors, and at least one pressure receiving part of the differential pressure sensor is made of non-rubber.