JPS6121322B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a control method for a mix-type high-speed gas burner used in industrial furnaces and improvements to the device.

Conventional control methods for MIX-type high-speed gas burners for industrial furnaces can be roughly divided into ○IGAS control (gas control).
There are two types of independent control: control) or on ratio control.
It is as follows.

Gas control keeps the combustion air constant and controls only the fuel gas.

On-ratio control is a method of controlling one of the combustion air or fuel gas and having the other follow.

Gas control can always maintain the ejection flow velocity of the burner, but as the amount of fuel gas is restricted, excessive air combustion occurs, resulting in large fuel losses. on·
Ratio control, on the other hand, causes no fuel loss, but as the combustion rate is reduced, the burner jet flow velocity is lost, causing temperature differences and problems, especially in furnace equipment that requires uniform heating.

The present invention combines gas control and on-ratio control, with gas control on the low combustion side and on-ratio control on the high combustion side. Since the burner discharge flow velocity is switched to gas control from the point where the burner discharge flow velocity is lost due to the on-ratio control throttle, the burner discharge flow velocity can be maintained. Additionally, since gas is controlled only on the low combustion side, the amount of excess air is significantly reduced, and fuel loss due to excess air is also reduced.

Embodiments of the present invention will be described based on the drawings.

Air supply source 1 such as an air pump (e.g. 900 mm
The air from Aq) is guided to the nozzle mix type high speed burner 4 of the industrial furnace 3 via air passages 2a and 2b, and is also introduced to a fuel gas supply source 5 such as a gas tank.
(For example, normally around 2000mmAq in gas path 6a)
The fuel gas is led to the burner 4 via gas passages 6a, 6b, and 6c.

The furnace temperature signal F of the furnace temperature f from the temperature detector 7 installed in the industrial furnace 3 is input to the temperature controller 8, and the set temperature signal G of the set temperature g from the program setting device 9 for setting the furnace temperature is also input to the temperature controller 8. It is input to controller 8. The temperature controller 8 compares the furnace temperature signal F with the set temperature signal G, and inputs the temperature difference g−f between the two to the comparison setting device 10 as a temperature difference signal H.

The gas control valve 11 inserted into the gas paths 6a, 6b, 6c for gas control has an electric positioner 12.
The opening state of the air passage 2 is controlled by
The opening state of the on-ratio control air control valve 13 inserted in ports a and 2b is controlled by an electroelectric positioner 14.

Based on the temperature difference signal H, the ratio setting device 10 sets the electric positioner when the difference g−f between the furnace temperature f of the industrial furnace 3 and the set temperature g of the program setting device 9 for setting the furnace temperature is less than a predetermined value ΔH. The opening degree of the gas control valve 11 is controlled so as to send the optimum amount of fuel gas to maintain the interior of the industrial furnace 3 at a predetermined temperature via the electrostatic positioner 14, and the air control valve 13 is controlled to a predetermined minimum open state via the electric positioner 14. to hold. Further, when the difference g−f between the furnace temperature f of the industrial furnace 3 and the set temperature g of the program setting device 9 for setting the furnace temperature is equal to or higher than a predetermined value ΔH, the ratio setting device 10 controls the While maintaining the opening degree of the control valve 11 at the maximum open state, the opening degree of the air control valve 13 is adjusted between the minimum open state and the maximum open state via the electric positioner 14, and the adjustment is performed using a diaphragm described later. The opening degree of the pressure equalizing valve 17 is adjusted via the device 16 to control the optimal amount of fuel gas to maintain the interior of the industrial furnace 3 at a predetermined temperature. That is, the air passage 2b between the air control valve 13 and the burner 4 is connected to the diaphragm device 16 via the pressure guiding pipe 15.
a homogeneous valve 17 inserted into the gas passages 6a, 6b between the fuel gas supply source 5 and the gas control valve 11;
The opening degree of the gas control valve 11 is determined between the minimum open state and the maximum open state by the air pressure in the air passage 2b between the air control valve 13 and the burner 4 (shown on the pressure gauge 18) and the maximum open state of the gas control valve 11. The gas pressure in the gas passage 6c between the gas control valve 11 and the burner 4 (as shown on the pressure gauge 19) in this state is controlled to be equal. Therefore, when the air control valve 13 is in the minimum open state, the pressure equalizing valve 17 is also in the minimum open state, but if the gas control valve 11 is not in the maximum open position in this state, the pressure gauge 19 is low, but when the gas control valve 11 is in the maximum open state, the pressure gauges 18 and 19 display the same pressure, and air and gas at the same pressure are sent to the burner 4. .

The control method will be explained. The difference between the temperature g set by the program setting device 9 and the actual temperature f measured by the temperature detector 7 becomes a deviation in the temperature controller 8, and the control signal H
is sent to the ratio setter 10. The ratio setting device 10 has a dial for setting the switching point between gas control and on-ratio control within the range of the input signal H from the temperature controller 8, and the switch between gas control and on-ratio control can be set in advance. A point (a point at which it is necessary to maintain the ejection flow velocity of the burner 4) is set in advance.

When the control signal from the temperature controller 8 to the ratio setter 10 is within the gas control range, the ratio setter 10 outputs a signal to operate the gas control valve 11 via the electric positioner 12, and the air control valve 13, the output of the switching point between gas control and on-ratio control is outputted via an electric positioner 14. In other words, gas
During control, the air control valve 13 maintains the minimum open state at the switching point between gas control and on-ratio control, and only the gas control valve 11 adjusts its opening degree. In addition, the instrument of the ratio setting device 10 has a structure that allows the output signal to the gas control valve 11 to be automatically adjusted so that the gas control valve 11 is in the maximum open state at the switching setting point between gas control and on-ratio control. It's summery.

When the control signal H from the temperature controller 8 to the ratio setter 10 is within the on-ratio control range, the ratio setter 10 outputs a signal to operate the air control valve 13 via the electric positioner 14. The control on the fuel gas side is an equalization valve type on-ratio control in which the pressure equalization valve 17 is adjusted by the pressure conduit 15 by the control operation of the air control valve 13, and the pressure gauges 18 and 19 are controlled to have the same pressure. It's summery. At this time, the gas control valve 11 is already fully open at the switching point between gas control and on-ratio control as described above, so it does not become a resistance part that causes pressure loss after the pressure equalization valve 17, and the on-ratio There will be no problem with ratio control.

As described above, the method for controlling a gas burner for an industrial furnace according to the present invention is to control an industrial furnace equipped with a mix-type high-speed gas burner that separately sends air and fuel gas to the burner. A gas control type control is performed to send a desired amount of fuel gas, and on the high combustion side, an on-ratio control type control is performed to send an air amount that exceeds the above-mentioned certain amount and a gas amount that increases or decreases in response to the air amount. In addition, the switching point between the gas control type control and the on-ratio control type control is set near the point where the fluid ejection speed from the burner starts to become insufficient in the on-ratio control type control.

Further, the control device for a mix-type high-speed gas burner for industrial furnaces according to the present invention guides the air supply source 1 to the nozzle mix-type high-speed burner 4 through the air passages 2a, 2b, and guides the air supply source 1 along the flow of the air passages 2a, 2b. An air control valve 13 and a pressure guiding pipe 15 are provided, and the fuel gas supply source 5 is guided to the burner 4 through gas passages 6a, 6b, 6c, and the gas passages 6a, 6
A pressure equalizing valve 17 and a gas control valve 11 are installed along the flow of steps b and 6c, and the set temperature signal G from the program setting device 9 for setting the furnace temperature and the furnace temperature signal from the temperature detector 7 installed in the industrial furnace 3 are provided. The temperature controller 8 compares the set temperature signal G and the furnace temperature signal F, and calculates the temperature difference g−f between the set temperature g and the furnace temperature f. The configuration is such that the signal H is input to the ratio setter 10, and on the low combustion side below the switching point between gas control type control and on-ratio control type control, the air control valve 13 is opened to the minimum by the output of the ratio setter 10. state and on the high combustion side above the switching point, the air control valve 13
An electric positioner 14 is provided to adjust the opening degree of the
Further, on the low combustion side below the switching point, the opening degree of the gas control valve 11 is adjusted by the output of the ratio setting device 10, and on the high combustion side above the switching point, the electric current is used to keep the gas control valve 11 in the maximum open state. A positioner 12 is provided, and a pressure guiding pipe 15 is further connected to a pressure equalizing valve 17 via a diaphragm device 16.

That is, in FIG. 3, in the conventional type with only gas control, the air control valve was open as indicated by D-E, resulting in excess air in the entire combustion range and lowering the combustion efficiency. In addition, in the conventional type with on-ratio control alone, the air control valve is A-C-
Since the opening was as shown in E, the gas jetting flow rate was slow on the low combustion side, making uniform heating of the furnace difficult. However, in the case of the present invention, since air is fed in as in B-C-E, the amount of excess air can be significantly reduced by using only the excess air on the low combustion side, and the combustion efficiency can be greatly reduced without significantly reducing the combustion efficiency. It is possible to uniformly heat the furnace without running out of outflow gas.

Note that the minimum open state of the pressure equalizing valve 17 is defined as a state in which the pressure equalizing valve 17 is not completely closed so as to allow a desired minimum amount of fuel gas to pass through.
As shown in FIG. 2, the pressure equalizing valve body 17C is completely closed and the minimum amount adjusting valve
The gas may also flow through a bypass path 17b having 7a.

Further, the minimum open state of the gas control valve 11 may be configured such that it is not completely closed so that a desired minimum amount of fuel gas passes through, or the gas control valve main body 11C is completely closed as shown in FIG. Alternatively, the gas may flow through a bypass passage 11b having a minimum amount adjustment valve 11a.

Furthermore, the minimum open state of the air control valve 13 can be configured so that it is not completely closed so as to allow a desired minimum amount of air to pass through, or it can be configured such that the air control valve 13 is completely closed and the minimum amount of air is allowed to pass through, as shown in FIG. Adjustment valve 13a
Air may be made to flow through the bypass path 13b having the following.

[Brief explanation of the drawing]

The drawings are for explaining the embodiment of this invention. Fig. 1 shows the overall principle, Fig. 2 shows the principle of partially modified parts, and Fig. 3 shows the amount of fuel gas sent to the burner and air control. It is a graph which shows the relationship of the opening degree of a valve. 1... Air supply source, 2a, 2b... Air path, 3
...Industrial furnace, 4...Burner, 5...Fuel gas supply source, 6a, 6b, 6c...Gas path, 7...Temperature detector, 8...Temperature controller, 10...Ratio setting device, 11 ... Gas control valve, 12 ... Electric positioner, 13 ... Air control valve, 14 ... Electric positioner, 15 ... Impulse pipe, 16 ... Diaphragm device, 17 ... Pressure equalization valve, F ... Temperature signal, f ……
Furnace temperature, G... Set temperature signal, g... Set temperature, H...
Temperature difference signal.

Claims (1)

[Claims] 1. In an industrial furnace equipped with a mix-type high-speed gas burner that separately sends air and fuel gas to the burner, gas control that sends a certain amount of air and a desired amount of fuel gas on the low combustion side. On the high combustion side, on-ratio control type control is performed to send an air amount exceeding the above-mentioned certain amount and a fuel gas amount that increases or decreases in response to the air amount, and gas control type control and on-ratio control type control are performed. - A control method for a mix-type high-speed gas burner for industrial furnaces, characterized in that the switching point of the ratio control type control is set near the point where the fluid ejection velocity from the burner starts to be insufficient in the on-ratio control type control. . 2. The air supply source 1 is guided to the nozzle mix type high-speed burner 4 through the air passages 2a, 2b, and an air control valve 13 and a pressure pipe 15 are provided along the flow of the air passages 2a, 2b. is guided to the burner 4 through gas paths 6a, 6b, and 6c, and a pressure equalizing valve 17 and a gas control valve 11 are provided along the flow of the gas paths 6a, 6b, and 6c, and a program setting device for setting the furnace temperature is provided. The wiring is such that the set temperature signal G from 9 and the furnace temperature signal F of the temperature detector 7 set in the industrial furnace 3 are input to the temperature controller 8, and the temperature controller 8 receives the set temperature signal G and the furnace temperature signal. The temperature difference g−f between the set temperature g and the furnace temperature f is determined as a temperature difference signal H.
On the low combustion side below the switching point between gas control type control and on-ratio control type control, the air control valve 13 is
An electric positioner 14 is provided to maintain the opening of the air control valve 13 in the minimum open state and adjust the opening degree of the air control valve 13 on the high combustion side above the switching point, and to adjust the opening degree of the air control valve 13 on the low combustion side below the switching point. An electric positioner 12 is provided to adjust the opening degree of the gas control valve 11 and keep the gas control valve 11 in the maximum open state on the high combustion side above the switching point. A control device for a mix-type high-speed gas burner for an industrial furnace, characterized in that it is connected to a pressure valve 17.