JP2020200973A - Heating power control device - Google Patents

Abstract

To prevent combustion failure when heating power is strong, in a heating power control device including a flow regulating valve 2 interposed in a gas supply passage to a burner nozzle 1 and a governor 3 interposed in the gas supply passage and located upstream of the flow regulating valve in which the governor 3 includes a diaphragm 34 covering an end surface on the side opposite to a valve seat 33 of a secondary pressure chamber 32 and a governor valve 36 varying an opening of a valve hole 33a formed on the valve seat 33 and coupled to the diaphragm 34, and is configured to control differential pressure between secondary pressure and back pressure (pressure in a back pressure chamber 35 on the diaphragm back surface side) to predetermined set pressure.SOLUTION: A back pressure chamber 35 is communicated with a portion in a gas supply passage between a flow regulating valve 2 and a nozzle 1. Nozzle pressure that is gas pressure supplied to the nozzle 1 becomes back pressure, and a governor 3 performs pressure control so that differential pressure between secondary pressure and the nozzle pressure becomes set pressure.SELECTED DRAWING: Figure 1

Description

The present invention relates to a thermal power control device including a flow rate control valve provided in a gas supply path to a nozzle for a burner and a governor located in the gas supply path on the upstream side of the flow rate control valve. ..

Conventionally, in this type of thermal power regulation device, the governor is a valve seat between the primary pressure chamber on the upstream side, the secondary pressure chamber on the downstream side communicating with the flow control valve, and the primary pressure chamber and the secondary pressure chamber. The diaphragm that covers the end face on the opposite side of the valve seat of the secondary pressure chamber, the back pressure chamber that is partitioned by the diaphragm from the secondary pressure chamber, and the opening of the valve hole formed in the valve seat are variable. It has a governor valve connected to the diaphragm, and is configured to adjust the differential pressure between the secondary pressure, which is the gas pressure in the secondary pressure chamber, and the back pressure, which is the pressure in the back pressure chamber, to a predetermined set pressure. (See, for example, Patent Documents 1 and 2). Here, the back pressure chamber is open to the atmosphere, and the back pressure becomes atmospheric pressure.

In this case, even if the primary pressure, which is the gas pressure in the primary pressure chamber, fluctuates, the secondary pressure supplied to the flow control valve is adjusted to the set pressure. Therefore, the nozzle pressure, which is the gas pressure supplied to the nozzle, that is, the flow rate of the gas ejected from the nozzle (the thermal power of the burner) can be adjusted by the flow rate adjusting valve without being affected by the fluctuation of the primary pressure.

However, when the primary pressure falls below the set pressure due to the fluctuation of the primary pressure, the governor valve is fully opened and the secondary pressure becomes equal to the primary pressure, and the secondary pressure cannot be adjusted to the set pressure. Therefore, conventionally, the set pressure is set to be equal to or lower than the lower limit pressure in the expected fluctuation range of the primary pressure. Therefore, by fully opening the flow control valve during high heat, even if the nozzle pressure is boosted to the secondary pressure, that is, the set pressure, the set pressure itself is low, so the gas ejection speed from the nozzle is sufficient. It did not rise, and the amount of primary air sucked by the ejector was insufficient, resulting in a gas-rich state, which sometimes caused combustion failure.

Japanese Unexamined Patent Publication No. 2004-60898 (Fig. 4) Japanese Unexamined Patent Publication No. 2004-340432

In view of the above points, it is an object of the present invention to provide a thermal power adjusting device capable of preventing combustion defects at high thermal power.

In order to solve the above problems, the present invention is provided with a flow rate control valve provided in the gas supply path to the nozzle for the burner and located in the gas supply path on the upstream side of the flow rate control valve. A thermal power regulator equipped with a governor, the governor is a valve between a primary pressure chamber on the upstream side, a secondary pressure chamber on the downstream side communicating with a flow control valve, and a primary pressure chamber and a secondary pressure chamber. The opening of the valve hole formed in the seat, the diaphragm covering the end surface opposite to the valve seat of the secondary pressure chamber, the back pressure chamber partitioned by the diaphragm from the secondary pressure chamber, and the valve seat is changed. It has a governor valve connected to the diaphragm, and is configured to adjust the differential pressure between the secondary pressure, which is the gas pressure in the secondary pressure chamber, and the back pressure, which is the pressure in the back pressure chamber, to a predetermined set pressure. The back pressure chamber is characterized in that the back pressure chamber is communicated with a portion of a gas supply path between the flow rate control valve and the nozzle, and the nozzle pressure, which is the gas pressure supplied to the nozzle, becomes the back pressure.

According to the present invention, the governor adjusts the pressure so that the differential pressure between the secondary pressure and the nozzle pressure, that is, the pressure loss generated by the flow rate control valve, becomes the set pressure. Therefore, even if the primary pressure, which is the gas pressure supplied to the primary pressure chamber, fluctuates, the gas flow rate passing through the flow rate control valve is a constant amount (amount that causes a pressure loss of the set pressure) according to the opening degree of the valve. The pressure regulation function of the governor is exerted so as to be, and the fluctuation of the thermal power of the burner due to the fluctuation of the primary pressure can be reduced. Furthermore, at high heat, the differential pressure between the secondary pressure and the nozzle pressure becomes zero by opening the flow control valve fully, so the governor valve is not fully opened and the governor valve is fully open, and the primary pressure is primary. The pressure is supplied to the nozzle as it is. Therefore, when the heat is high, the nozzle pressure is not insufficient, the amount of primary air sucked by the ejector can be appropriately secured, and combustion failure does not occur.

Further, in the present invention, it is desirable that the set pressure is set to be equal to or lower than the lower limit pressure in the expected fluctuation range of the primary pressure. According to this, the nozzle pressure at the time of weak and medium heat, in which the pressure adjusting function of the governor is exerted, is stable regardless of the fluctuation of the primary pressure, and problems such as misfire do not occur.

Further, in the present invention, it is desirable that the set pressure can be variably set and the set pressure is lowered as the Wobbe index of the fuel gas used becomes higher. Here, it is necessary to lower the nozzle pressure as a whole as the Wobbe index of the fuel gas becomes higher. It is costly to replace the flow control valve in order to change the nozzle pressure as a whole. If the set pressure can be variably set as described above, the nozzle pressure can be changed as a whole by changing the set pressure, so that it is not necessary to replace the flow rate control valve when switching the gas type, which is advantageous in terms of cost. ..

The schematic sectional view of the thermal power control apparatus of embodiment of this invention.

With reference to FIG. 1, the thermal power adjusting device according to the embodiment of the present invention has a flow rate adjusting valve 2 interposed in a gas supply path to a nozzle 1 for a burner and an upstream of the flow rate adjusting valve 2 in the gas supply path. It is equipped with a governor 3 located on the side and interposed. The nozzle 1 faces the inflow port at the upstream end of the mixing pipe portion of the burner (not shown). Then, the fuel gas is injected from the nozzle 1 toward the inflow port, and the primary air is sucked by the ejector (suction by the ejector effect) along with this injection.

The flow rate control valve 2 includes a valve chamber 21 that communicates with the downstream side of the governor 3 via a communication port 21a, a valve seat 22 that forms a valve hole 22a that allows fuel gas to flow from the valve chamber 21 toward the nozzle 1, and a valve. It has a needle-shaped valve body 23 that can move forward and backward with respect to the valve seat 22 provided in the chamber 21. Then, by advancing and retreating the valve body 23 by an actuator (not shown) connected to the valve shaft 23a integrated with the valve body 23, the opening degree of the flow rate adjusting valve 2 (specifically, the opening degree of the valve hole 22a) is adjusted. Variable.

The governor 3 has a primary pressure chamber 31 in which fuel gas flows from the upstream portion of the gas supply path through the inflow port 31a, a secondary pressure chamber 32 having the communication port 21a on the side surface, and a primary pressure chamber 31. The valve seat 33 between the secondary compression chamber 32 and the diaphragm 34 covering the end surface of the secondary compression chamber 32 opposite to the valve seat 33, and the back of the secondary compression chamber 32 partitioned by the diaphragm 34. Inside the back pressure chamber 35 that urges the pressure chamber 35, the governor valve 36 connected to the diaphragm 34 that changes the opening degree of the valve hole 33a formed in the valve seat 33, and the diaphragm 34 in the direction approaching the valve seat 33. It has a spring 37 of the above. Here, the opening area of the valve hole 33a is S1, the effective pressure receiving area of the diaphragm 34 is S2, the primary pressure which is the gas pressure supplied to the primary pressure chamber 31 is P1, and the gas pressure in the secondary pressure chamber 32 is 2. The next pressure is P2, the back pressure which is the pressure in the back pressure chamber 35 is PB, the urging force of the spring 37 is F, and the force for pressing the diaphragm 34 in the direction away from the valve seat 33 is P1, S1 + P2, S2. Therefore, the force for pressing the diaphragm 34 in the direction approaching the valve seat 33 is P2 · S1 + PB · S2 + F. Since the governor valve 36 is displaced so that both of these forces are equal, the following equation,
P1, S1 + P2, S2 = P2, S1 + PB, S2 + F ... (1)
Is established, and from equation (1) to the following equation,
P2-PB = (P2-P1) · S1 / S2 + F / S2 ... (2)
Is obtained. Since S1 is considerably smaller than S2, the first term on the right side of equation (2) can be regarded as zero, and the following equation,
P2-PB = F / S2 ... (3)
Is established. This means that P2-PB, that is, the differential pressure between the secondary pressure and the back pressure is adjusted to a predetermined set pressure (= F / S2).

Then, in the present embodiment, the back pressure chamber 35 communicates with the portion of the gas supply path between the flow rate control valve 2 and the nozzle 1 via the communication port 35a. Therefore, the nozzle pressure, which is the gas pressure supplied to the nozzle 1, becomes the back pressure. Therefore, the governor 3 adjusts the pressure so that the differential pressure between the secondary pressure and the nozzle pressure becomes the set pressure.

According to the present embodiment, even if the opening degree of the flow rate control valve 2 changes, the differential pressure between the secondary pressure and the nozzle pressure does not change, but for that purpose, the gas flow rate passing through the flow rate control valve 2 (this). The flow rate is equal to the flow rate of the gas ejected from the nozzle 1), and the opening degree of the flow rate control valve 2 is changed so that the pressure loss (difference pressure between the secondary pressure and the nozzle pressure) generated by the flow rate control valve 2 becomes constant. It needs to be changed accordingly. Therefore, the flow rate of the gas ejected from the nozzle 1, that is, the thermal power of the burner can be variably adjusted by the flow rate control valve 2. Then, even if the primary pressure fluctuates, the pressure of the governor 3 is adjusted so that the gas flow rate passing through the flow rate control valve 2 becomes a constant amount (amount that causes a pressure loss of the set pressure) according to the opening degree of the valve 2. The function is exhibited, and the fluctuation of the thermal power of the burner due to the fluctuation of the primary pressure can be reduced. Further, at high heat, the pressure difference between the secondary pressure and the nozzle pressure becomes zero by opening the flow rate control valve 2 fully, so that the pressure adjusting function of the governor 3 is not exhibited and the governor valve 36 is fully opened. Then, the primary pressure is supplied to the nozzle 1 as it is. Therefore, when the heat is high, the nozzle pressure is not insufficient, the amount of primary air sucked by the ejector can be appropriately secured, and combustion failure does not occur.

By the way, the set pressure is set to be equal to or lower than the lower limit pressure in the expected fluctuation range of the primary pressure. According to this, the nozzle pressure at the time of weak and medium heat power at which the pressure adjusting function of the governor 3 is exerted is stable regardless of the fluctuation of the primary pressure, and problems such as misfire do not occur.

Further, in the present embodiment, a spring receiver 38 for the spring 37 is provided in the back pressure chamber 35, and the position of the spring receiver 38 can be adjusted by the adjusting screw 39. The set pressure can be variably set by adjusting the position of the spring receiver 38 with the adjusting screw 39.

Here, it is necessary to lower the nozzle pressure as a whole as the Wobbe index of the fuel gas becomes higher. In this case, it is conceivable to replace the flow rate control valve 2 to change the nozzle pressure as a whole, but this is disadvantageous in terms of cost. On the other hand, if the set pressure can be variably set as in the present embodiment, the nozzle pressure can be changed as a whole by changing the set pressure. If the set pressure is set lower as the Wobbe index of the fuel gas used becomes higher, it is not necessary to replace the flow rate control valve 2 when switching the gas type, which is advantageous in terms of cost.

Although the embodiments of the present invention have been described above with reference to the drawings, the present invention is not limited thereto. For example, in the above embodiment, the flow control valve 2 having a needle-shaped valve body 23 that can move forward and backward is used, but another type of flow control valve having a rotatable valve body or the like can also be used. Is.

1 ... Nozzle, 2 ... Flow control valve, 3 ... Governor, 31 ... Primary pressure chamber, 32 ... Secondary pressure chamber, 33 ... Valve seat, 33a ... Valve hole, 34 ... Diaphragm, 35 ... Back pressure chamber, 36 ... Governor valve , 37 ... Spring.

Claims (3)

A thermal power control device including a flow rate control valve provided in a gas supply path to a nozzle for a burner and a governor located upstream of the flow rate control valve in the gas supply path. Is the primary pressure chamber on the upstream side, the secondary pressure chamber on the downstream side communicating with the flow control valve, the valve seat between the primary pressure chamber and the secondary pressure chamber, and the valve seat of the secondary pressure chamber. It has a diaphragm that covers the end face on the opposite side, a back pressure chamber that is partitioned by a diaphragm from the secondary pressure chamber, and a governor valve that is connected to the diaphragm and that changes the opening of the valve hole formed in the valve seat. In a device configured to adjust the differential pressure between the secondary pressure, which is the gas pressure in the secondary pressure chamber, and the back pressure, which is the pressure in the back pressure chamber, to a predetermined set pressure.
The back pressure chamber is a thermal power adjusting device characterized in that the nozzle pressure, which is the gas pressure supplied to the nozzle, is the back pressure, which is communicated with the portion of the gas supply path between the flow control valve and the nozzle. The thermal power adjusting device according to claim 1, wherein the set pressure is set to be equal to or lower than a lower limit pressure in an expected fluctuation range of the primary pressure, which is a gas pressure supplied to the primary pressure chamber. The thermal power adjusting device according to claim 1 or 2, wherein the set pressure can be variably set, and the set pressure is set lower as the Wobbe index of the fuel gas used becomes higher.

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