JPS6011296B2 - Combustion control safety device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides a forced air combustion system in which the gas amount ratio is kept within a certain set range to obtain a good combustion state.
The purpose is to automatically stop the operation of the combustion equipment if the ratio exceeds the set range due to changes in gas pressure, voltage changes, blockages in the supply and exhaust passages, the effects of strong winds, etc. be.

In conventional forced air combustion systems, in order to detect abnormal conditions in the fan that supplies combustion air, a switch that operates on the fan discharge opens and closes the gas supply path, and a switch that operates based on the pressure difference between the suction and discharge sides of the fan is used. A differential pressure switch was used to open and close the gas supply path, but both were based on wind pressure and had no function at all to detect air volume, making them insufficient as a safety device.

Furthermore, Jikai Publication No. 49-78941 discloses a system in which two pressure switches are opened and closed based on the pressure difference between the air supply pressure and the gas supply pressure, and the valve function of the gas circuit is adjusted by a motor by opening and closing the pressure switches. It is shown. In this application, the gas valve function is controlled so that air pressure and gas pressure are always equal, and a conventionally known zero governor is operated electromechanically, and considering the performance of the pressure switch, considerably high accuracy is expected. It is clear that the product will be large and expensive due to its composition. The present invention uses a gas pressure regulator and a differential pressure generator to easily follow and constrain the gas supply pressure to the air supply pressure. It attempts to stop the operation mechanically, and is inherently superior as a safety function compared to conventional methods.
This enables small size and low price.

Examples thereof will be described below with reference to the accompanying drawings.

In Fig. 1, 1 is a general air duct that sucks combustion air, and is connected to an air chamber 3 on the upstream side of the mixing section 2. Reduce pressure. Then, the mixed gas and air pass through the enlarged portion 5 to recover static pressure and are burned in the burner 7. This combustion chamber is taken up by a heat exchanger 8 and the exhaust gases are discharged through an exhaust duct 10 by a fan 9. Next, the gas circuit 11 supplies gas from a cock 12 through a solenoid valve 13 and a gas pressure regulator 14 to a gas nozzle 15 provided facing the mixing chamber 6 of the mixing section 2 . Reference numeral 16 denotes a pressure equalization pipe that transmits the air pressure gas in the air chamber 3 to the diaphragm back pressure chamber of the pressure regulator 14, and is used to ensure that the outlet pressure of the gas pressure regulator 14 follows the air pressure in the air chamber 3. It is.

Next, 17 is a differential pressure switch, and a diaphragm 20
On one side there is a gas pressure chamber 18, into which the inlet pressure of the gas nozzle 15 is introduced, and on the other side there is an air pressure chamber 19, into which the air pressure of the air chamber 3 of the mixing section 2 is introduced. Therefore, the diaphragm is displaced by two rivers due to the pressure difference between the gas pressure and the air pressure, and the contact 21 is opened and closed by this displacement. Now, in this device, symbols are defined as follows for explanation. Air pressure in the air chamber 3 of the mixing section 2...Pai Pressure in the mixing chamber 6 of the mixing section 2...Outlet pressure of the Pno gas pressure regulator 14...Pzo:Pni(
The amount of combustion air (equal to the inlet gas pressure of the gas nozzle 15)...
...Qc gas amount...
Qg excess air ratio...
As is well known, Q and Pai-P
The relationship for no is approximately a square curve as shown in FIG.

Furthermore, due to the difference between the inlet pressure Pni of the gas nozzle 15 and the pressure Pno at the outlet (mixing chamber in this case), Qg becomes a square root curve as shown in FIG. In other words, Qc; F south 6 on the Ka string......[1-Qg=Kg's Pni-Pn
6 ・・・・・・・・・(2}Here, Pai=Pzo=Pni...
・・・・・・If the gas pressure follows the air side so that the relationship is as shown in '31, then there will be ants. - The excess air ratio becomes '4' and becomes constant.

However, it is well known that the outlet pressure Pzo of the gas pressure regulator changes depending on the gas amount, and as shown in Fig. 6, when Pai changes from Pai, to Pai2 at a given gas amount Q, It is easy for Pzo to undergo the same change, but when a gas amount change is involved, it is inevitable that Pzo will have some error even if Pai is constant.

Generally, as shown in FIG. 6, there is a tendency to decrease as the flow rate increases. In addition, even if Pai is constant, it is difficult to establish the '3' formula under all conditions due to changes in the gas supply source, errors during production, etc. Now, Pni=Pz
o = Pai 1 △P ...... [5] If the error occurs, then M = K invading western seaweed: b t, . (6) It becomes 10 Pai-Pn city, resulting in M fluctuation, and the degree changes depending on the value of Pai-Pno even for the same ΔP.

Conversely, the range of allowable M of the burner is set to an upper limit Mmax and a lower limit Mm.
If it is set as in, △P(=Pni
The value of △P can be obtained from the formula {6}, as shown in Figure 7, and the allowable value of △P is Pai - Pno
It depends. The tolerance △P corresponding to Pai-Pno at a certain air volume is plus △P, minus △P2 as shown in Figure 7.
As long as the error is within this range, there is no risk of poor combustion. Focusing on this, in the present invention, a pressure detector 17 is provided, and Pai and Pni (=P
zo) is introduced, and when ΔP or ΔP2 shown in FIG. 7 is reached, the contact 21 opens so as to close the solenoid valve 13 to stop the gas supply. FIG. 2 shows a part of the electric circuit, and shows the electrical contacts 21 of the pressure detector 17.
A manual switch 22 is inserted in parallel.

Before combustion starts, the fan 9 rotates, creating a pressure difference between the air chamber 3 and the mixing chamber 6, but since the solenoid valve 13 is closed, the outlet pressure Pzo of the gas pressure regulator 14 and the inlet pressure Pni of the gas nozzle 15 are Pai-Pn are all equal to the mixing chamber pressure Pno
o acts on the pressure detector 17, the contact 21 remains open, and the solenoid valve cannot open. Therefore, when the manual pushbutton switch 22 is temporarily closed, gas is supplied, Pzo=Pni is made almost equal to Pai, the contact 21 is closed by the action of the pressure detector 17, and the pushbutton switch 2 is closed.
Even if 2 is released, operation continues. FIG. 3 shows another embodiment of the electric circuit system, which has a delay relay 23 and its contacts 24,
The cross point 21 of the differential pressure switch 17 and the delay relay contact 24 are in parallel.

When the manual switch 22 is closed, the delay relay contact 24 closes, but after a certain period of time, it automatically opens.
Operation can be started as in the case of FIG. Further, the manual switch 22 can also be conveniently used as a power switch for equipment. As explained above, the present invention detects the difference between air pressure and gas pressure, which is the most problematic for an excess air ratio stabilizing device, so if this difference is within a predetermined range, stable combustion can be maintained. High stability compared to other wind pressure switches.

This safety device alone can protect you from abnormal conditions such as an abnormal rise or fall in gas pressure, abnormalities in the fan, abnormalities in the supply/exhaust duct system, and abnormalities caused by strong outside air winds applied to the terminal of the supply E duct. The device only requires a differential pressure switch and a manual switch to start operation, and can be constructed at low cost.

[Brief explanation of drawings]

FIG. 1 is a schematic configuration diagram of a combustion device showing an embodiment of the present invention;
Figures 2 and 3 are diagrams showing the specifics of the electric circuit, Figure 4 is a diagram showing the relationship between the amount of combustion air and the pressure difference before and after the differential pressure generator, and Figure 5 is a diagram showing the relationship between the pressure difference between the outlet and inlet of the gas nozzle. Figure 6 is a diagram showing the relationship between the gas volume and gas volume; Figure 6 is a diagram showing the relationship between gas pressure regulator outlet pressure and gas volume; Figure 7 is a diagram showing the relationship between the change in excess air ratio and the differential pressure difference across the mixing section. be. 1...Air supply path (air supply duct), 2...Mixing section, 3...Air chamber, 6...Mixing chamber, 1
1... Gas circuit, 13... Solenoid valve, 14...
...Gas pressure regulator, 17...Pressure detector. Figure 1, Figure 2, Figure 8, Number 4, Mother Leopard, Figure 5, Figure 6, Figure 7

Claims (1)

[Claims of Claims] 1. A differential pressure generator that is installed in a fuel supply passage and generates a differential pressure depending on the amount of combustion air, and a gas outlet pressure that is related to the air pressure in an air chamber upstream of the differential pressure generator. a gas pressure regulator;
a gas nozzle provided between the outlet of the gas pressure regulator and the mixing chamber on the downstream side of the differential pressure generator; a pressure detector that operates based on the pressure difference between the air pressure on the upstream side of the differential pressure generator and the gas pressure regulator outlet pressure; and a solenoid valve provided in the circuit, the pressure detector comprising:
A combustion control safety device that closes the solenoid valve when the pressure difference exceeds a predetermined value. 2. Combustion control according to claim 1, wherein the pressure detector sets a predetermined value of the pressure difference that closes the solenoid valve equal to the same pressure difference that reaches the upper and lower limits of the allowable excess air ratio of the combustion section. Safety device. 3. The pressure sensor according to claim 1, wherein the predetermined value of the pressure difference for closing the solenoid valve is set to a different value depending on whether the gas pressure regulator outlet pressure is higher or lower. Combustion control safety device. 4. A gas circuit according to claim 1, characterized in that a differential pressure switch is provided which operates based on a difference in air pressure to open and close a solenoid valve provided in the gas circuit, and a starting switch is provided in parallel with the differential pressure switch. Combustion control safety device.