JPS6172922A - Boiler combustion control device - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] [Field of Application] The present invention relates to a combustion control device for a boiler, and in particular, the present invention relates to a combustion control device for a boiler. , relates to a combustion control device that ensures proportional control of combustion.

[Prior art and its problems]

Combustion control in steam pressure generating boilers applied to heating systems, etc. has conventionally been proportionally controlled using the valve opening of a fuel control valve connected to a control motor that is operated by the output of a pressure converter that responds to the steam pressure. At the same time, the start and stop of combustion was carried out in a fail-safe manner using a combustion safety control device.This conventional combustion control is reliable when the size of the boiler load corresponds to the combustion capacity of the boiler. Proportional control allows the desired steam pressure to be obtained continuously, but for example, when applied to heating equipment, it is necessary to prevent the load on the steam boiler from exceeding the range of combustion capacity due to a rise in room temperature, etc. If this occurs, even if the fuel supply is throttled down, the proportional control will not work due to excessive supply, and the pressure switch installed for safety will operate the 0N10FF control.This ON10 F F control This has the drawback that heat loss is large due to operations such as pre-purge performed by the combustion safety control device to start and stop combustion, and therefore economic loss is large.

[Summary of the invention]

The present invention was made in view of such circumstances, and includes:
The boiler load is detected by signal processing, and when the load becomes lighter than a predetermined value, the scale of the valve opening of the fuel control valve for boiler combustion is changed. It should be configured as much as possible.

Hereinafter, the present invention will be described in detail based on Examples.

[Detailed description of examples]

FIG. 4 shows an overall configuration diagram of combustion control of a boiler to which the combustion control device according to the present invention is applied.

1 is a boiler, and the inside is filled with water 2.
Steam 5 generated by the heat of the flame 4 burned in the combustion chamber 3 is supplied to a load (not shown) through a pipe 6. 7 is the combustion flue.・8 is a combustion safety control device that starts and stops combustion in a fail-safe manner, and after performing pre-purging with the fan motor 9, it drives the igniter 10 to perform ignition operation, and opens the main valve 11 to start the burner 12. Execute ignition. 13Vi flame sensor and confirms the ignition of the flame. Here, the fan motor 9 supplies air for combustion after ignition.

Reference numeral 14 denotes a pressure converter, which converts the vapor pressure of the steam 5 into, for example, a corresponding electrical resistance value through mechanical displacement, etc. Conventionally, the control motor 15 is driven by monitoring changes in this resistance value, etc. , the valve opening degree of the proportional valve 17 for fuel supply through the linkage 16 and the opening degree of the damper 18 for adjusting the air amount are proportionally controlled. The proportional valve 17 and damper 18 are controlled proportionally in order to achieve the vapor pressure value, and air-fuel ratio control is realized by controlling the proportional valve 17 and damper 18 synchronously by one control motor 15. ing.

Reference numeral 19 denotes a pressure switch with hysteresis, which turns OFF when the steam pressure exceeds the pressure setting value of the pressure converter 14 and reaches a predetermined upper limit value, and notifies the combustion safety control device 8 to that effect, thereby starting the combustion process. It instructs to stop, and turns ON when the steam pressure drops to a predetermined lower limit pressure value to instruct restart of combustion. When the boiler load is large enough to correspond to the combustion capacity of the boiler, the steam pressure is controlled by the ninth pressure switch 1 controlled by the pressure transducer 14.
9 will not operate, but if the load becomes light beyond this range, the pressure switch 19 will operate and proportional control will no longer work.

Reference numeral 20 denotes a combustion device according to the present invention, in which the pressure switch 1 is connected via a conventionally provided combustion safety control device 8.
9 is read, the load of the boiler is determined, and the scale of the scale converter 21 is selected, thereby converting the operation scale of the control motor 15. Further, 22 is a release pressure switch, which is a steam pressure pressure switch for detecting that the boiler load has returned to a normal state.

FIG. 5 shows an operational diagram of conventional boiler combustion control. The horizontal axis is the flow of time, and the vertical axis is the steam pressure. Between the pressure setting value set in the pressure transducer 14,
An OFF operating point, which is the upper limit value, and an ON operating point, which is the lower limit value, of the pressure switch 19 are set. When the burner 12 starts combustion, the steam pressure increases over time, but if the combustion capacity of the boiler and the load appropriately correspond, the control motor 15 is driven by the pressure transducer 14).
The opening of the proportional valve 17 is controlled to maintain the desired pressure setting. On the other hand, when the load on the boiler becomes lighter than its combustion capacity, the steam pressure continues to rise even if the opening degree of the proportional valve 17 is reduced to a predetermined lower limit, and eventually the pressure switch 19 turns OFF. The point will be reached. This OF
When the F operating point is reached, the combustion safety control device 8 detects the OFF operation of the pressure switch 19 and forcibly stops combustion. As a result, the steam pressure is changed to O of the pressure switch 19.
When this ON operating point is reached, the combustion safety control device 8 turns the pressure switch 19 ON.
It will detect motion and restart combustion according to a predetermined sequence. When the combustion is restarted, the combustion safety control device 8 performs a bleed-purge operation, resulting in extremely large heat loss.Therefore, the conventional technology has the drawback of large economic losses. Moreover, as shown in Figure 4, 0N10
Since it is FF control, the steam pressure value fluctuates greatly between the OFF operating point and the ON operating point of the pressure switch 19, which also has the disadvantage that temperature control on the load side cannot be achieved sufficiently.

Next, the operation of the present invention will be described in detail to overcome these drawbacks of the prior art. FIG. 2 shows a hardware configuration diagram of a combustion control device 20 according to the present invention, a combustion safety control device 8 that is an external device, a release pressure switch 22, a pressure converter 14, and a scale converter 21.
and a connection diagram with the control motor 15. Here, the combustion control device 20 includes a CPU 23, a ROM 24, a RAM
25, and the CPU 23 executes a flowchart shown in FIG. 1, which will be described later, according to a predetermined program stored in the ROM 24 in advance.

The 0N10FF mode of the pressure switch 19 is read into the combustion control device 20 via the combustion safety control device 8, and the C
It is determined whether the PU23 is in a false or false mode. Further, the ON10FF mode of the release pressure switch 22 is directly read into the combustion control device 20, and is similarly read into the CPU 2.
3 decides. The scale converter 21 is configured by selecting different resistance values, for example, as shown in FIG. The opening scale will be changed. In this embodiment, the pressure transducer 14 is assumed to be a device whose electrical resistance value changes in response to steam pressure, and the control motor 15 is assumed to be a device that operates by adjusting the change in resistance value by balancing the bridge circuit. Therefore, an example in which a resistance value is selected as the scale converter 21 has been exemplified, but the present invention is not limited to this, and may be configured based on the operating principles of the pressure converter 14 and the control motor 15.

FIG. 1 shows a flowchart executed by the CPU 23. The combustion control device 20 constantly checks whether the pressure switch 19 has reached the OFF operating point. If the load is normal combustion with an appropriate load, the steam pressure is proportionally controlled near the pressure setting value set by the pressure converter 14, as shown in the operational diagram of the present invention in FIG. If a phenomenon in which the load becomes lighter occurs, combustion becomes excessive and the steam pressure increases, eventually reaching the OFF operating point of the pressure switch 19. The combustion safety control device 8 is connected to this pressure switch 1.
As soon as the OFF operation of the pressure switch 19 is detected, combustion is stopped, so the steam pressure decreases with time, and eventually reaches the ON operation point of the pressure switch 19. The CPU 23 of the combustion control device 20 calculates the time 1. from the OFF operation to the ON operation of the pressure switch. Count. If the load is sufficiently light, the steam 5 will not be used sparingly, so the 1 hour t0 will be sufficiently long at this time. From now on, when to becomes larger than a predetermined value T0, the combustion control device 20 of the present invention assumes that the load has become lighter and switches the scale converter 21 to control the control motor 1.
By narrowing the drive range of the proportional valve 17, the valve opening scale of the proportional valve 17 is changed to a smaller value.

This switching will restrict the fuel supply, so
When the combustion safety control device 8 detects the ON operation of the pressure switch 19 and restarts combustion, the steam pressure is proportionally controlled to the pressure setting value of the pressure converter 14.

Furthermore, as shown in the flowchart of FIG. 1 and the operation diagram of FIG. The drop in steam pressure can be controlled by switching the release pressure switch 22 to O.
This can be handled by detecting the N operation and returning the scale converter 21 to its original state. As described above, the present invention improves O
This makes it possible to always achieve proportional control without N10FF control.

The present invention is not limited to this embodiment. For example, in the embodiment shown in FIG. 2, the scale converter 21 has two-stage switching; It may be selected based on the size of . Further, in the operation diagram of FIG. 3, an example is shown in which the ON operating point of the release pressure switch 22 is set to a steam pressure lower than the ON operating point of the pressure switch 19, but the present invention is not limited to this. , O of the release pressure switch 22
The N operating point may be set to a vapor pressure higher than the ON operating point of the pressure switch 19.

Furthermore, in this embodiment, the release pressure switch 22 is
The N operating point is only used to detect that the boiler load has been restored, and the release pressure switch 22 is turned off.
Set the operating point between the OFF operating point of the pressure switch 19 and the pressure setting value, and once t0≧T0, the load becomes light.
) After t, when the load becomes light again and the release pressure switch 22 reaches the OFF operating point, the scale converter 21 is switched to lower the pressure switch 19 to the OFF operating point.
It is also possible to configure the combustion safety control device 8 so that the FF operating point is not reached, that is, the combustion safety control device 8 does not stop the combustion. At this time, if the ON operating point of the release pressure switch 22 is set between the ON operating point of the pressure switch 19 and the pressure setting value, combustion can be controlled before the pressure switch 19 operates 0N10FF, so a preferable control is achieved. It will become a reality.

〔Effect of the invention〕

As explained above, according to the present invention, the boiler load condition is detected by signal processing, and when the load becomes lighter than a predetermined value, the valve opening degree scale of the boiler combustion fuel control valve is adjusted. By changing the configuration so that the proportional control region is applied when the load is light, wasteful fuel consumption can be suppressed and economic loss can be reduced.

[Brief explanation of drawings]

FIG. 1 is a flowchart executed by the CPU of the combustion control device according to the present invention, FIG. 2 is a hardware configuration diagram showing an embodiment of the combustion control device according to the present invention, and FIG. 3 is the device according to the present invention. FIG. 4 is an overall configuration diagram of combustion control of a boiler to which the combustion control device according to the present invention is applied, and FIG. 5 is an operation explanation diagram showing the operating state of combustion control in a conventional boiler. It is a diagram. 8... Combustion safety control device, 14... Pressure transducer, 15... Control motor, 21... Scale converter, 22... Release pressure switch, 2
0... Combustion control device, 23... CPU,
24...ROM. 25...RAM 0 Patent applicant: Hirayo Iron Works Co., Ltd. Patent applicant: Yamatake Honeywell Co., Ltd. (2 others) Engraving of drawings; no changes in ζ] Figure 1 1-9-36 Hirakawa Co., Ltd. Iron Works Procedures Amendment (Voluntary) Name of Ichiaki Temple Commissioner General Relationship with the case of a person who corrects boiler combustion control equipment Patent Applicant Address Name (666) Yamatake Honeywell Co., Ltd. (Other 1)
Name) Agent Postal code 105 Address 1-4-10 Nishi-Shinbashi, Minato-ku, Tokyo Subject of amendment

Claims (2)

[Claims] (1) Control by reading the operating mode of the pressure switch via the combustion safety control device, determining the size of the boiler load based on the pressure converter output, and selecting the scale of the scale converter using the pressure converter output. In a boiler combustion control device that converts the operating scale of a motor, the load of the boiler is detected, and when the load becomes lighter than a predetermined value, the valve opening of the fuel control valve for combustion of the boiler is adjusted. A combustion control device for a boiler, characterized in that the scale of is changed so that a proportional control region is achieved in the above-mentioned light load state. (2) The load is detected from the OFF operation of the pressure switch.
The combustion control device for a boiler according to claim 1, wherein the combustion control device for a boiler is performed during the time until the N operation is reached.