JP2526464B2 - Boiler combustion control device - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a combustion control device for reducing the number of times of starting and stopping a combustion device.

[0002]

2. Description of the Related Art Conventionally, in a once-through hot water boiler, the temperature of hot water is detected and the combustion device is turned on based on the detected temperature.
N-OFF control is performed. For example, when the hot water temperature reaches 65 ° C, the burner is stopped and the hot water temperature is set to 60
When the temperature drops to ℃, the burner is controlled to operate.

[0003]

However, since the once-through hot water boiler has a small amount of water, the combustion device frequently repeats starting and stopping when the low load state (particularly 1/2 load state) is continued for a long time. Cause Such frequent start and stop significantly shortens the life of the device. Further, in the oil-fired hot water boiler, even when the amount of soot generated during steady combustion is extremely small, the amount of soot generated during ignition and extinguishing increases sharply.
There is also a problem that this adheres to the heat exchange surface of the can body and hinders heat transfer, resulting in a marked decrease in the heat exchange rate.

[0004]

The present invention has been made in view of the above-mentioned problems, and the detected value is OFF based on the detected value of at least one of hot water temperature, steam pressure and steam temperature. Stops the combustion device when the set value is exceeded
The detected value is different from the OFF setting value.
The combustion device is activated when the ON set value is lower than the low value.
In the boiler, the start / stop cycle detecting means for detecting the start / stop cycle of the combustion device, and the start / stop cycle according to a predetermined table of the relationship between the start / stop cycle of the combustion device and the corresponding combustion control differential value And a differential value changing means for changing the combustion control differential value based on the value of the start / stop cycle detected by the detecting means.

[0005]

According to the above-mentioned structure, the start / stop of the combustion device detected by the start / stop cycle detecting means is determined according to a predetermined table for the relationship between the start / stop cycle of the combustion device and the corresponding combustion control differential value. An appropriate differential value can be selected based on the cycle, and the number of times of starting and stopping the combustion device can be reduced.

[0006]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT A preferred embodiment of the present invention will be described below with reference to the drawings. FIG. 3 is a system configuration diagram showing an embodiment in which the present invention is applied to a hot water boiler. (1) is a once-through hot water boiler, which connects a number of vertical water pipes between the upper and lower headers and heats the water pipes by the combustion device (2) to heat the water in the water pipes. Use warm water.
A circulation pump (5) and a heat exchanger (6) are connected in series by piping between the hot water outlet (3) and the hot water return port (4) of the boiler (1). (7) is a three-way valve, which is inserted in the hot water supply line (14) connected to the hot water outlet (8) on the load side of the heat exchanger (6),
The amount of hot water from the heat exchanger (6) and the cistern tank (1
The mixing ratio of cold water from 5) is automatically controlled. (9) is the load side hot water return port of the heat exchanger (6). (10), (11), (12) are pipe connection parts of the three-way valve (7), (10) is hot water inlet, (11) is cold water inlet, (12)
Indicates a hot water outlet.

(16) is a first temperature detector for detecting the hot water temperature T1 of the upper part of the boiler (1) inside the can. (17) is a second temperature detector, which is the outlet side hot water temperature (hot water temperature) T2 of the heat exchanger (6).
To detect. These temperature detectors usually use thermistors.

Next, an embodiment of the control circuit will be described with reference to FIG. (18) is an operation switch such as an operation switch and a combustion switch, and (19) is an indicator. The above combustion device (2),
The circulation pump (5) and the indicator (19) are controlled according to a control procedure stored in advance in a control unit (20) including a microcomputer. That is, the circulation pump (5) is operated by the operation switch (1
While 8) is ON, continuous operation is performed. The combustion device (2) is the second control for the combustion device main control under the condition that the operation switch (18) is ON.
Based on the temperature detected by the temperature detector (17), the hot water temperature is turned on.
When the temperature is below the set value (TON), the combustion is ON and the hot water temperature is O.
When the FF set value (TOFF) or more, the combustion is controlled to be turned off. Here, TOFF-TON = differential value ΔT, and its initial setting value is ΔT0. Also, the temperature detected by the second temperature detector (17) is indicated by the indicator (19).
It is supposed to be displayed in real time.

The first temperature detector (16) is connected to the second temperature detector (1
7) and the OR circuit are configured to control the combustion device. When the temperature detected by the first temperature detector (16), that is, the temperature of the hot water inside the can exceeds the OFF set value, the combustion is turned off, and when it falls below the ON set value, the combustion is turned on. The combustion device is interlocked to the OFF state.

When the temperature information is displayed by a 3-digit LED,
The first temperature detector and the second temperature detector can be displayed in different cases depending on whether they are operating normally. That is, when both temperature detectors are operating normally, the value of the first temperature detector is lit and displayed, and when the first temperature detector is disconnected and the second temperature detector is operating normally, −−
"-" Is lit, and the first temperature detector operates normally and the second
If the temperature detector is broken, the value of the first temperature detector is displayed blinking. If both temperature detectors are broken, "-" is displayed.
"-" Is displayed in a blinking manner. If you do this,
With one temperature indicator, the disconnection state of two temperature detectors can be known at the same time.

Further, in a boiler having a function of performing antifreeze combustion for antifreeze, an antifreeze switch is provided, and the following control can be performed in combination with the combustion switch. That is, when the combustion switch is ON and the freeze prevention switch is ON, normal combustion is performed, and the combustion switch O
Even when N and the antifreezing switch are OFF, normal combustion is performed. When the combustion switch is OFF and the antifreezing switch is ON, antifreezing combustion is performed. When the combustion switch is OFF and the antifreezing switch is OFF, the control is stopped. By doing so, normal combustion is performed in the ON-OFF state of the combustion switch regardless of whether the antifreeze switch is ON-OFF, and when the combustion switch is turned OFF, the antifreeze combustion is automatically set. I will never forget to set it.

The differential value ΔT is automatically changed according to the number of times the combustion device is started and stopped according to the control procedure shown in FIG. This auto differential function reduces the number of times the combustion device is started and stopped. The control unit
(20) is provided with a changeover switch (not shown) for switching between a manual position where the differential value ΔT can be manually adjusted and an automatic position which forms an automatic differential function.

A first embodiment of the automatic differential operation will be described below with reference to FIG. Step S
In 1, it is determined whether the operation switch is ON. Yes
If it is determined that it is determined that the pre-purge is started, the process proceeds to step S2. If YES is determined in step S2, the process proceeds to step S3, and the prepurge start time is stored in the prepurge start time storage memory M1. Next, in step S4, it is determined whether or not the previous prepurge start time is stored in the memory M1. Immediately after the operation switch is turned on, the pre-purge start time is not stored, so the determination is NO, and otherwise the determination is YES. If YES is determined, the process proceeds to step S5, the cycle time from the previous prepurge start time to the current prepurge start time is calculated, and in step S6,
The calculated value is stored in the cycle time calculation memory M2.

Next, in step S7, it is determined whether or not data has been stored in the memory M2 for 5 cycles. If NO, the process returns to step S1. If YES,
The process proceeds to step S8, obtaining the total value t of the data for the last 5 cycles stored in the memory M2. In this method, as shown in FIG. 5, the cycle times are totaled, and when the next cycle time is stored, the cycle times are totaled. The calculation method can be obtained by subtracting from the total time of and then adding. Then, in step S9, based on the value of the total value t, determines a differential value ΔT in accordance with the differential value change table shown in FIG. In the differential value change table, the initial value + the total value t
It is composed of increasing values, and for example, if t is 1900 seconds, the differential decision value is set to 1 ° C.
It is the added value. The initial setting value can be changed.

Next, in step S10, it is determined whether the determined value exceeds a predetermined value, for example, 8 ° C. Where N
If it is determined to be O, the determined value is stored in the differential value storage memory M3 in step S11. On the other hand, YE
If it is determined to be S, the process proceeds to step S12, and the differential value is set to 8 ° C. and stored in the memory M3. The combustion device is ON-OFF controlled according to the stored value.

When the operation switch is turned off, NO is determined in step S1, the process proceeds to step S13, and the contents stored in the memories M1, M2, M3 are cleared.

With the auto differential function described above, the more the number of times the combustion device (2) is started and stopped, that is, t
The smaller the value of, the larger the differential value is controlled, and as a result, the number of times the combustion device is started and stopped is reduced.

A second embodiment of the automatic differential operation will be described below with reference to FIG. Step S
In 1, it is determined whether the operation switch is ON. Yes
If it is determined that it is determined that the pre-purge is started, the process proceeds to step S2. If YES is determined in step S2, the process proceeds to step S3, and the prepurge start time is stored in the prepurge start time storage memory M1. Next, in step S4, it is determined whether or not the previous prepurge start time is stored in the memory M1. Immediately after the operation switch is turned on, the pre-purge start time is not stored, so the determination is NO, and otherwise the determination is YES. If YES is determined, the process proceeds to step S5, the combustion cycle time Δt from the previous prepurge start time to the current prepurge start time is calculated, and the calculated value is stored in the cycle time calculation memory M2 in step S6. .

Next, in step S7, the next differential value is determined from the calculated cycle time and the current differential value according to the differential value determination table shown in FIG. The determined differential value is stored in the differential value storage memory M3 in step S8. The combustion device (2) is controlled according to the value stored in the memory M3. The differential value determination table uses the immediately preceding combustion cycle time Δt and the current differential value as variables, and the next differential value is set based on experimental results. The differential value determination table can be modified based on the experimental result so that the control becomes stable, and the fuzzy control can be performed by setting the next differential value based on the fuzzy theory.

When the operation switch is turned off, NO is determined in step S1 and the process proceeds to step S9 to clear the contents stored in the memories M1, M2 and M3.

With the auto differential function as described above, the differential value is controlled to increase as the number of times the combustion device (2) is started and stopped increases.
The number of times the combustor starts and stops is reduced.

The present invention is not limited to the above embodiment, and the can structure may be a hot water storage type, and can be applied to combustion control of a steam boiler. When applied to the combustion control of a steam boiler, the combustion device is ON-OFF controlled based on the steam pressure or the steam temperature, and the auto differential function is applied to the steam pressure or the steam temperature. Further, the configuration of the differential value determination table may be, in addition to the total cycle time-differential value, the average cycle time-differential value, or the unit time start / stop count-differential value. Furthermore, it is also applicable to a boiler that controls the combustion device in three positions: ON (high combustion / low combustion switching) -OFF.

Further, when changing the differential value, in the above embodiment, the TOFF value is fixed and the TON value is changed, but the differential change value is 50%.
It is possible to adjust the TON value and the TOFF value one by one, and the differential change value can be adjusted to the TON value and the TOFF value at an arbitrary ratio.

[0024]

EFFECTS OF THE INVENTION Since the present invention has the above-described structure, it is possible to detect whether or not the number of times of starting and stopping the combustion device is large, and to perform ON-OFF control of the combustion device according to the detected starting and stopping status. The differential value of can be changed to an appropriate value, and as a result, it is possible to reduce the number of times of starting and stopping of the combustion device, shorten the life of the device due to frequent start and stop, and ignite. It is possible to solve problems such as a decrease in heat exchange rate due to the attachment of soot that occurs at the time of fire extinguishing.

[Brief description of drawings]

FIG. 1 is a flowchart showing a first embodiment of an automatic differential operation in the present invention.

FIG. 2 is a block diagram showing an outline of a control circuit in one embodiment of the present invention.

FIG. 3 is a system configuration diagram showing an embodiment of the present invention.

FIG. 4 is a table diagram in the first embodiment of the auto differential operation of the present invention shown in FIG.

FIG. 5 is an explanatory diagram of the auto differential operation according to the first embodiment of the present invention shown in FIG.

FIG. 6 is a flowchart showing a second embodiment of the automatic differential operation in the present invention.

FIG. 7 is a table diagram in the second embodiment of the automatic differential operation of the present invention shown in FIG.

[Explanation of symbols]

 1 Boiler 2 Combustor 3 Hot water outlet 4 Hot water return port 5 Circulation pump 6 Heat exchanger 7 Three-way valve 8 Load side hot water outlet 9 Load side hot water return port 10 Hot water inlet 11 Cold water inlet 13 Hot water outlet 13 Load 14 Hot water supply line 15 Sisturn tank 16 First temperature detector 17 Second temperature detector 18 Operation switch 19 Display 20 Control section

Claims (2)

(57) [Claims] 1. A hot water temperature, based on at least one of the detection value of the steam pressure and steam temperature, the detection value
When it exceeds the OFF set value, the combustion device is stopped and the detected value
Is lower than the OFF setting value by the differential value
In a boiler that operates a combustion device when the ON / OFF value is less than a certain ON set value, the relationship between the start / stop cycle detection means for detecting the start / stop cycle of the combustion device, and the combustion control differential value corresponding to the start / stop cycle of the combustion device According to a predetermined table, the combustion control of the boiler, characterized by comprising: a differential value changing means for changing the combustion control differential value based on the value of the start / stop cycle detected by the start / stop cycle detecting means. apparatus. 2. A hot water temperature, based on at least one of the detection value of the steam pressure and steam temperature, the detection value
When it exceeds the OFF set value, the combustion device is stopped and the detected value
Is lower than the OFF setting value by the differential value
In the boiler that operates the combustion device when the temperature becomes less than the ON set value, the start / stop cycle detecting means for detecting the start / stop cycle of the combustion device, the start / stop cycle of the combustion device, and the differential value for the current combustion control are used as variables. According to a predetermined table for the combustion control differential value, the differential value changing means for changing the combustion control differential value based on the start / stop cycle detected by the start / stop cycle detecting means and the current combustion control differential value is provided. A boiler combustion control device characterized by being provided.