JP2001090940A - Control device for automatic switching of kind of combustion gas - Google Patents

Abstract

PROBLEM TO BE SOLVED: To switch the kind of combustion gas automatically. SOLUTION: A combustion control device is provided with a combustion gas flow rate control device 23, a combustion air flow rate control device 24, a gas burner 12, into which the combustion gas and the air, which are controlled by the flow rate control devices, are supplied, and a combustion air to fuel ratio control means 25, controlling the flow rate ratio to burn the combustion gas and the air optimally in the gas burner. In this case, an optimum combustion air to fuel ratio automatic changing means, monitoring the change of density of gas through a gas density meter 30 to judge a time point, whereat the change of a density value, higher than a preset deciding value, is generated, as the starting of switching of gas and change the combustion air to fuel ratio by changing a theoretical combustion air volume set value of gas to air in accordance with the density value of the gas, is provided.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention aims at stabilizing the temperature of a combustion chamber at a certain target temperature by performing a combustion air-fuel ratio control, which is a control of a mixture ratio of combustion gas and combustion air, and controlling each combustion gas. BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a combustion gas type automatic switching control device which controls a flow rate of combustion air by a flow control valve and uses a plurality of types of combustion gas by switching as a heating fuel gas.

[0002]

2. Description of the Related Art Heretofore, when switching the gas type of combustion gas, switching by manual operation is basically performed, and the flame of each burner on site is directly monitored with the naked eye. That is, the switching timing of the gas is determined from the color of the flame, the length of the flame, etc.
The manual switching of parameters such as (μ, O) and the gas density correction set value has been performed, relying on human eyes and a long-standing feeling.

[0003]

In the above-described conventional combustion gas type switching method, the timing of switching the gas is determined by directly observing the flame with the naked eye. There were many involved. Also, due to human judgment, the switching timing varies every time, and it has been difficult to realize stable gas combustion. In addition, when a gas type switching notification (telephone) is sent from the energy center, which is the gas supply side, the combustion control device side, which is the gas use side, has to wait for a mature person on site to prepare for the cut-off of the gas type. Furthermore, if the gas type is changed while insufficient communication or incorrect communication of the gas type occurs, the ratio of combustion gas and combustion air is disturbed and air rich
(High air ratio), the oxygen concentration in the furnace increases, and the products in the combustion chamber are oxidized and the quality deteriorates, or conversely, they become gas rich (high gas ratio) and black smoke in the combustion chamber And, in the worst case, unburned gas fills the combustion chamber and there is even a danger of explosion. Further, when the combustion gas type is manually switched, the control valve for controlling the combustion gas flow rate and the control valve for controlling the combustion air flow rate are always in a fixed opening degree, and the temperature control in the combustion chamber is temporarily stopped. Furthermore, although it depends on the total combustion gas flow rate and the piping volume of the gas piping, it takes a considerable amount of time to completely switch the gas type. In addition, problems such as variations in the indoor temperature caused by the temporary interruption of the temperature control in the combustion chamber have been considered indispensable.

SUMMARY OF THE INVENTION Accordingly, the present invention has been made to solve the above-mentioned problems, and has as its object to have no adverse effect on the original control of the temperature in the combustion chamber, the control of the flow rate of the combustion gas, and the control of the flow rate of the combustion air. Without the need for manual intervention,
An object of the present invention is to provide a combustion gas type automatic switching control device capable of safely switching a combustion gas type while maintaining stable combustion.

[0005]

A combustion gas type automatic switching control device according to the present invention is provided with a combustion gas flow control device equipped with a flow control valve and controlling the flow rate, and a combustion gas flow control device equipped with a flow control valve and controlling the flow rate. A combustion air flow control device,
A gas burner to which the combustion gas and the air controlled by these flow control devices are supplied; and a combustion air-fuel ratio control means for controlling a flow ratio of the combustion gas and the air in the gas burner in order to optimally burn the combustion gas and the air. In the provided combustion control device, when the combustion gas is changed to another type of gas, the change in the gas density is monitored by a gas density meter, and the change in the density value which is equal to or higher than a predetermined determination value is monitored. Is determined to be the start of gas switching, and the optimal combustion air-fuel ratio automatic changing means for changing the combustion air-fuel ratio by gradually changing the set theoretical combustion air amount of gas and air in accordance with the density value of gas. It is characterized by having.

Further, in the combustion gas automatic switching control device according to the present invention, there is further provided a means capable of switching between an automatic switching mode for performing automatic gas type switching and a manual switching mode based on human judgment. It is characterized by having.

Further, in the combustion gas type automatic switching control device according to the present invention, when the change in gas density due to the switching of the combustion gas reaches a predetermined value, the manipulated variable calculation in the combustion gas flow control device is performed. And means for changing parameters of a proportional gain, an integration time, and a differentiation time.

That is, the combustion gas type automatic switching control device according to the present invention obtains the combustion gas flow rate control and the combustion air flow rate control by a certain calculation so that the temperature of the combustion chamber is stabilized at a preset target temperature. It is controlled to burn at the specified optimum combustion ratio, which enables control of the temperature in the combustion chamber, but stable combustion gas and combustion air combustion without interrupting the temperature control in the combustion chamber when switching the combustion gas type. If this is possible, two types of mixed gas can be corrected by correcting the combustion gas flow based on the gas density input from the gas density meter, and calculating and automatically changing the optimal combustion ratio of gas and air (air-fuel ratio μ). Even in this case, it is possible to perform the optimal combustion, and it is possible to perform control such that the temperature in the combustion chamber always follows a certain temperature set value without temporarily stopping the temperature control in the combustion chamber.

Further, according to the present invention, the switching operation of the combustion gas, which has conventionally been required by two or more persons, can be automatically performed by an unmanned person.

Also, in case that the gas density meter fails due to some trouble and does not display a normal instruction, the combustion control device starts operating at the timing when gas switching is started on the combustion gas supply side (energy center). Total combustion gas usage flow rate (burning amount) is integrated, and the timing of the mixed gas reaching the combustion burner is measured by back calculation from the gas pipe volume value from the energy center to the gas burner of the combustion control device, and various combustion conditions are set. A backup function that automatically changes the values (gas density flow correction, theoretical air volume μ ₀ , air-fuel ratio μ) is also provided, and a stable indoor temperature is secured by suppressing variations in the indoor temperature due to the temporary interruption of the combustion chamber temperature control. Can be.

[0011]

Embodiments of the present invention will be described below in detail with reference to the drawings. FIG. 1 is a block diagram showing a configuration of a combustion gas type automatic switching control device of the present invention. This control device supplies a combustion gas and air to a gas burner 12 installed on the inner wall of the combustion chamber 11 through a gas pipe 13 and an air pipe 14 provided outside the combustion chamber 11. This is a device for controlling a combustion furnace for burning 12. The control device includes a combustion chamber temperature control device 21, an air-fuel ratio control device 22 for controlling the combustion ratio of combustion gas and combustion air, a combustion gas flow control device 2
3. Combustion air flow controller 24, flow ratio calculator 2
5, a combustion gas flow control valve 26 and a combustion air flow control valve 27 are included. The measured output temperature i of the indoor temperature sensor 15 installed in the combustion chamber 11 and the target combustion chamber temperature set value a1 are supplied to the combustion chamber temperature control device 21 as inputs. The output of the combustion chamber temperature controller 21 is supplied to a flow ratio calculator 25. The combustion gas flow control device 23 is supplied with the output of the flow rate calculator 25 and the output of the gas flow sensor 28 provided in the gas pipe 13 as inputs, and the output thereof outputs the combustion gas provided in the gas pipe 13. The flow control valve 26 is controlled. The combustion air flow control device 24 is supplied with the output of the flow ratio calculator 25 and the output of the air flow sensor 29 provided in the air pipe 14 as inputs, and outputs the combustion air provided in the air pipe 14 by the output. Flow control valve 27
Control. A gas density sensor 30 is provided in the gas pipe 13. The output of the gas density sensor 30 is a gas density flow compensator 31.
Is supplied to the input of the combustion gas flow control device 23 via the. The output of the gas density sensor 30 is also supplied as an input signal to the air-fuel ratio control device 22 via the gas density flow rate corrector 31. This air-fuel ratio control device 22 includes:
The output of the air flow sensor 29 is supplied as an input.

In the control apparatus for automatically switching the type of combustion gas of the present invention thus constituted, the indoor temperature sensor 15
In order to make the actual measurement value i of the target follow the target combustion chamber temperature set value a1, the flow set values of the combustion gas flow control device 23 and the combustion air flow control device 24 are operated to control the target combustion chamber temperature. The combustion gas flow control device 23 controls the flow rate of the combustion gas flow rate control valve 26 based on the combustion gas flow rate set value of the flow rate calculator 25 so that the flow rate instruction of the combustion gas flow rate sensor 28 follows the set value. I have. Similarly to the above combustion gas flow control device, the combustion air flow control device 24 also controls the flow rate of the combustion air flow sensor 29 based on the combustion air flow rate set value of the flow ratio calculator 25 so that the flow rate instruction of the combustion air flow sensor 29 follows the set value. At 27, the flow rate is controlled. Then, in order to realize the optimum combustion, the combustion gas flow rate set value and the combustion air flow rate set value are not changed by the flow rate calculator 25 even if the combustion chamber temperature fluctuates rapidly even when the combustion chamber temperature fluctuates. As described above, there is a limitation based on the setting value limitation method.

Incidentally, the gas density meter 30 is connected to the gas pipe 1.
Measure the density of the gas flowing in 3; if the density is high, decrease the flow rate of the gas flowing in the gas pipe 13; conversely, if the density is low, increase the flow rate of the gas flowing in the gas pipe 13 It is used as a flow rate correction. The gas density meter 30 also constantly monitors the density of the gas flowing through the gas pipe 13 for the purpose of determining the type of gas, and sends a stoichiometric air set value to the combustion air-fuel ratio control device 22 according to a change in the gas density meter.
The configuration is such that b2 and the air-fuel ratio set value b1 are automatically changed.

FIG. 2 is a block diagram of a combustion gas type automatic switching control apparatus showing an operation system diagram of automatic parameter change by a combustion gas density meter in more detail. In the figure, the same elements as those in FIG. 1 are denoted by the same reference numerals, and description thereof will be omitted. This control system is supplied with a density value from the combustion gas density meter 30, and a gas density determiner 35 for determining the gas density here.
Gas density determiner theoretical air quantity determination output is supplied 35 mu _O calculator 36 and the air-fuel ratio correction arithmetic unit 37 is added. The outputs of these computing units 36 and 37 are supplied to the combustion air-fuel ratio controller 22 as the set value μ _O of the stoichiometric air amount and the set value μ of the air-fuel ratio.

The automatic switching control device for the combustion gas type shown in FIG.
A / manual changeover switch 32 and a gas flow rate setting fixed calculator 38 which is switched by the automatic / manual changeover switch 32 are added. The automatic / manual selector switch 32 selectively switches the output of the flow rate calculator 25 and the output of the gas flow rate fixed calculator 38 and supplies the output to the combustion gas flow controller 23 as a flow rate set value. The output of the automatic / manual changeover switch 32 is also supplied to the gas flow rate setting arithmetic unit 38 so that the flow rate immediately before switching when switching from the automatic mode to the manual mode is used as the output of the gas flow rate setting arithmetic unit 38. Have been.

FIG. 3 is a diagram for explaining the operation when the gas type is changed in the combustion gas type automatic switching control device of FIG. In FIG. 7A, the horizontal axis represents time t, and the vertical axis represents gas density ρ, and shows the temporal change of gas density. The horizontal lines PSV1 and PSV2 in the figure are defined values for determining the judgment output of the gas density judgment unit 35 in FIG. The gas density determiner 35 determines in which region the gas density is relative to these specified values PSV1 and PSV2, that is, whether the gas density is smaller than the specified values PSV1 and PSV1 and PSV2.
It is determined whether the value is between V2 or greater than PSV2. PSV1 and PSV2 are, for example, 1.
If the values are selected as 71 and 0.47, BPG is larger than 1.71 and COG is smaller than 0.47, so that the gas type can be distinguished. FIG. 3B shows the output of the air-fuel ratio correction calculator 37 when the horizontal axis represents time t and the vertical axis represents the air-fuel ratio μ. The air-fuel ratio correction calculator 37 outputs, for example, an air-fuel ratio μ2 corresponding to the COG gas while the gas density is smaller than the specified value PSV1, and outputs a value between the gas density smaller than the specified value PSV1 and PSV1 and PSV2. If the value has increased, μ2 + α is output. The gas density further increases,
When it exceeds PSV2, the air-fuel ratio correction calculator 37 outputs, for example, the air-fuel ratio μ1 corresponding to the BPG gas. When the gas density decreases from the specified value PSV2 to a value between PSV1 and PSV2, the air-fuel ratio correction calculator 37 outputs μ1-α. Then, when the gas density further falls below PSV2, the air-fuel ratio correction calculator 37 outputs μ2.

As described above, in the combustion gas type automatic switching control device of FIG. 2, the combustion ratio between the combustion gas and the combustion air performed in the flow rate ratio calculator 25 is corrected by the output of the combustion gas density meter 30. , Also theoretical air volume
The set values of (μ _O ) and the air-fuel ratio (μ) are calculated by the stoichiometric air amount calculator 36 and the air-fuel ratio correction calculator 37 in accordance with the gas density to enable the optimum combustion.

The automatic / manual switch 32 is capable of switching between an automatic mode and a manual mode. When the automatic mode is selected, stable combustion can be performed by the above-described automatic control. In the combustion gas switching operation when the manual mode is selected, the combustion chamber temperature control is temporarily suspended, and the manual gas changeover switch is operated to set the flow rate set value of each of the combustion gas flow control system and the combustion air flow control system. It becomes fixed from the point in time, and becomes constant value flow control by each simple flow control. After that, the flame of the burner is monitored with the naked eye, the timing at which the combustion gas is switched is determined, and various set values are changed manually.When the combustion gas is completely switched, the manual gas switch is turned off to control the temperature in the combustion chamber. Is an operation to resume.

The automatic / manual switching means is provided, for example, on the assumption that the gas density meter 30 cannot measure the gas density normally due to some trouble. From the start timing of switching
Calculate from the gas usage flow rate (burning amount) of the current number of all combustion burners in the combustion device and the volume of gas piping from the gas supply side switching point to each combustion burner of the combustion device, etc. Measure the timing at which the switched mixed gas reaches each burner of the combustion device, and automatically change the theoretical combustion air set value (μO) to the set value that matches the gas type to be switched at the mixed gas arrival timing, It is equipped with a backup process to prevent poor combustion due to gas types having different gas densities.

By the way, the gas density value changes due to the above-mentioned change of gas type. However, if the flow rate values of the fluids having different densities are calculated in the same manner, a considerable error occurs in the flow rate value. The corrector 31 corrects the gas flow rate to the gas density value and quickly responds to changes in the density to calculate a normal flow rate. In addition, the control amount of the valve opening of the gas flow control valve 26 is different from the control value of the valve opening degree of the gas flow control valve 26 as well as the flow rate value is different due to the above-mentioned difference in density. It leads to hunting.

FIG. 4 is a block diagram showing a configuration of a gain switch for preventing such hunting. Here, the gas density determiner 35 to which the output of the gas density meter 30 is supplied constantly monitors the density of the combustion gas and determines whether or not the density exceeds a predetermined value PSV1 set in advance as shown in FIG. , While this value is exceeded, changeover switches 41, 42, 43
To change the proportional gain of the operation amount calculation for the density difference of the combustion gas from P1 to P2, the integration time from I1 to I2, and the differentiation time from D1 to D2. In this case, in order to prevent hunting of the control, as shown in FIG. 3, a specified value PSV1 for the switching operation and a specified value PSV2 for return (<PSV).
1) has a difference of ΔP.

Thus, according to the present embodiment, safe and stable burner combustion and temperature control in the combustion chamber can be achieved without adversely affecting the operation even while the product is in the combustion chamber. Also, by correcting and setting the parameters of the combustion gas flow rate correction and the PID calculation of the combustion gas flow rate control valve according to the gas density change, the flow rate error due to the gas density difference and the control due to the difference in gas flow rate controllability. Instability can be prevented. Also, as a backup function, it is equipped with a response to failure of the gas density meter,
Fully automatic combustion gas type switching control is possible.

[0023]

As is apparent from the above description, according to the present invention, it is possible to prevent the temperature of the combustion chamber from being disturbed. . In addition, automation has made it possible to reduce the number of personnel involved in the manual switching work that has been performed up to now.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a schematic configuration of an embodiment of a combustion gas type automatic switching control device according to the present invention.

FIG. 2 is a block diagram showing a detailed configuration of a main part of the embodiment shown in FIG. 1;

FIG. 3 is an operation explanatory view of the embodiment shown in FIG. 2;

FIG. 4 is a block diagram showing a detailed configuration of a main part of the embodiment shown in FIG. 1;

[Explanation of symbols]

REFERENCE SIGNS LIST 11 combustion chamber 12 gas burner 13 gas pipe 14 air pipe 15 indoor temperature sensor 21 combustion chamber temperature control device 22 air-fuel ratio control device 23 combustion gas flow control device 24 combustion air flow control device 25 combustion gas flow control device 26 combustion gas flow control Valve 27 Combustion air flow control valve 28 Gas flow sensor 29 Air flow sensor 30 Air flow sensor 35 Air flow sensor 36 Theoretical air amount μ _O calculator 37 Air-fuel ratio correction calculator 38 Gas flow setting fixed calculator

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 3K003 AA01 AB02 AB03 AB06 AC02 BA06 CA03 CA05 CC02 DA01 DA03 3K065 QB17 RA00

Claims (3)

[Claims] 1. A combustion gas flow control device equipped with a flow control valve and controlled in flow rate, a combustion air flow control device also equipped with a flow control valve and controlled in flow rate, and a combustion air flow control device controlled by these flow control devices A combustion burner to which combustion gas and air are supplied, and combustion air-fuel ratio control means for controlling a flow ratio of the combustion gas and air in the gas burner for optimally burning the combustion gas and air. When the combustion gas is changed to another gas type, the change in the gas density is monitored by a gas density meter, and the gas switching is performed when a change in the density value exceeds a predetermined judgment value. Judging that the start of combustion, the optimum combustion air that changes the combustion air-fuel ratio by gradually changing the set theoretical combustion air amount of gas and air according to the gas density value A combustion gas type automatic switching control device comprising automatic fuel ratio changing means. 2. The combustion gas automatic switching control device includes:
2. The automatic combustion gas switching according to claim 1, further comprising means for switching between an automatic switching mode for performing automatic gas type switching and a manual switching mode based on human judgment. Control device. 3. When the change in gas density due to the switching of the combustion gas reaches a predetermined value, parameters of a proportional gain, an integration time, and a differentiation time for calculating an operation amount in the combustion gas flow control device. 3. The combustion gas type automatic switching control device according to claim 1, further comprising means for changing the combustion gas type.