JPH0387516A - Safety device for combustion equipment - Google Patents

Abstract

PURPOSE:To make the control by an oxygen sensor applicable to combustion equipment other than a Bunsen burner by providing first and second comparison circuits whereby a memory is updated when an output from a detective circuit, which reads oxygen concentration, is greater than a previous output in storage and an abnormality signal is outputted when an output is lower than a reference value. CONSTITUTION:When a scan timer has counted up, an output voltage from an oxygen sensor is read by a detective circuit 3 again; then the previous output voltage from the detective circuit 3 is read from the storage 4 and the two data are compared by a first comparison circuit 5; when the data read from the oxygen sensor 2 is greater in oxygen concentration than the data from storage 4, the data in the storage 4 is updated. When the data read from the oxygen sensor 2 is less in concentration than the data from the storage 4, a reference data is read from a reference value-setting circuit 12; a second comparison circuit 6 compares the reference with the difference between the data from the storage 4 and the data from the detective circuit 3, and in the case of discovery of abnormality, an alarm 7 is actuated and an automatic fire extinguisher 11 is put in action.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a safety device that directly detects the oxygen concentration of indoor air to prevent combustion abnormalities due to low oxygen conditions.

[Conventional technology]

If the degree of sealing in a room where a conventional combustor is used is high, oxygen will be depleted due to combustion, causing problems such as incomplete combustion in the combustor. For this reason, in the past, the characteristics of the combustor were used to indirectly determine the oxygen status from fluctuations in the flame current and to issue an abnormal signal, and zirconium-based oxygen concentration batteries were used to control indoor air containing oxygen. The state of oxygen in a room can be determined by determining the difference in oxygen partial pressure between the combustion gas and the combustion gas, which has consumed oxygen and is close to an anoxic state.

[Problem to be solved by the invention]

By the way, the conventional oxygen sensor described above uses combustion to detect oxygen, so in a Bunsen burner, in which a gaseous fuel with a stable fuel composition is mixed with an appropriate amount of air in advance and combusted, the combustion flame is also It is possible to stably change the flame current in accordance with the oxygen concentration in the room, and it is possible to supply air commensurate with the theoretical air amount to almost eliminate residual oxygen in the combustion gas. You can know the state of oxygen.

However, gas fuel burners other than the Bunsen method and liquid fuel burners supply a larger amount of air than is required for combustion, so a large amount of oxygen is present in the combustion gas. Small changes in the indoor air had little effect on the combustion flame, and it was not possible to correlate changes in flame current with the oxygen concentration in the room. In addition, in oxygen concentration batteries, combustion gas containing almost no oxygen is placed on one side of the electrode in a high-temperature atmosphere, and indoor air containing oxygen is placed on the other side. It generates an electromotive force, and the level of oxygen in the indoor air is detected based on the magnitude of this electromotive force, but if oxygen remains in the combustion gas, the electromotive force weakens and the level of oxygen in the indoor air is detected. cannot know.

Therefore, most burner safety devices that use oxygen sensors that are currently in practical use are for Bunsen burners that use vaporized fuel, and even for those that gasify liquid fuel and burn it in Bunsen burners, the composition of the gasified fuel is unstable. Because it was unstable, its reliability was poor.

[Means to solve problems]

This invention does not relate to an oxygen sensor related to combustion, but relates to a safety device for a combustor that uses an oxygen sensor that generates an electromotive force using oxygen contained in gas, such as a galvanic cell. An oxygen sensor 2 that changes its output voltage according to the oxygen concentration in the air in the room where it is installed, a detection circuit 3 that repeatedly reads the output voltage of the oxygen sensor 2 as needed, and a storage section 4 that stores the output of the detection circuit 3. and a first comparison circuit 5 that compares the previously stored output of the detection circuit 3 with the reread output of the detection circuit 3 and updates the storage unit 4 when the output is greater than the previously stored output; A second comparison circuit 6 is provided which compares the previously stored output of the detection circuit 3 with the re-read output and outputs an abnormal signal when the re-read output is lower than the reference value,
The abnormality signal from the second comparison circuit 6 is used to reduce the amount of combustion in the combustor, including activating the alarm 7 or extinguishing the fire.

In addition, the output stored in the storage unit 4 is not cleared immediately after the extinguishing operation, but a post-purge timer 8 and a memory clearing circuit 9 are provided, so that the output stored in the storage unit 4 is not cleared immediately after the extinguishing operation of the combustor 1.
For example, after one hour or more has passed, the memory clear circuit 9
It is configured to rewrite and clear the storage unit 4 with a specific value,
To start combustion while the post-versiter 4F 8 is in operation, the previously stored output of the storage unit 4 is used as is.

In addition, a third comparison circuit IO is provided to compare the preset usage limit value of the oxygen sensor 2 and the output of the detection circuit 3, and when the output voltage of the oxygen sensor 2 at the beginning of use is below the usage limit value, , the automatic fire extinguishing device 11 of the combustor 1 is activated to extinguish the combustor 1.

Furthermore, a circuit engineer 2 sets a reference value to be compared with a second comparison circuit 6.
is provided with a room temperature sensor 13 that detects the temperature inside the room in which the combustor 1 is installed, and the reference value compared by the second comparison circuit 6 is varied by the output of the room temperature sensor 3. Further, the oxygen sensor 2 detects the oxygen concentration in the indoor air, and in this invention, it is installed near the combustor 1, and the oxygen sensor 2 starts operating after the combustor 1 starts steady combustion. There is.

[Explanation of action]

An oxygen sensor that detects the content of oxygen in gas has a range of 0 to
Because it measures a wide range of 100%, it is not suitable for measuring a narrow range of 21% normal and 18% abnormal, such as oxygen in the air, and has many errors, making it extremely difficult to control combustors. It is difficult to use.

In this invention, the value of the electromotive force of the oxygen sensor does not directly correspond to the oxygen concentration, but an abnormality in oxygen is detected from the state of the electromotive force that changes when the combustor is used.The detection circuit 3 reads the output voltage of the oxygen sensor 2. and the read detection circuit 3
A storage unit 4 is provided for storing the output of The output of 4 and the output of the detection circuit 3 are compared, and when the oxygen data of the detection circuit 3 becomes worse than the reference value, an abnormality signal is issued to activate an alarm or extinguish the combustor. Therefore, even if the electromotive force of oxygen sensor 2 fluctuates, air pollution can be reliably detected by assuming that the oxygen in the indoor air at the start of combustion (the oxygen when the highest electromotive force is produced) is 21%. It became so.

In addition, the oxygen data in the storage unit 4 can be retained for a certain period of time by the post-purge timer 8 even after the fire has been extinguished, so that the air in the room is replaced little by little after the fire is extinguished, and combustion starts again before the oxygen concentration approaches that of the outside air. In such a case, by using the previous oxygen data in the storage unit 4 as is, it was possible to treat the air with the reduced oxygen concentration as normal air, thereby preventing the problem of the level at which the alarm was issued being out of order.

Furthermore, the detection method 1 always assumes that the electromotive force of the oxygen sensor 2 immediately after the start of combustion is the normal oxygen concentration in the air. Even when sufficient electromotive force cannot be obtained due to deterioration of the oxygen sensor 2 or the ambient temperature is too low, the method continues as usual. Since the alarm is activated, there is a risk that the level at which the alarm is issued will be drastically out of order. In this invention, when the safety device of the combustor is activated, the electromotive force of the oxygen sensor 2 is checked by the third comparison circuit 1.0, and if the alarm cannot be issued at the set oxygen concentration, the combustor 1 is forcibly extinguished. Safety has been increased by making it unusable.

In addition, the electromotive force of oxygen sensor 2 has a temperature dependence that decreases as the temperature decreases, and experiments have shown that the drop in voltage at low temperatures is smaller than the drop in voltage during oxygen depletion at high temperatures. stomach. Conversely, when the window is opened for ventilation, the oxygen sensor 2 cools down rapidly and the electromotive force decreases, even though the air is normal, the electromotive force of the oxygen sensor 2 becomes small, and the output difference becomes large, causing an abnormal signal. may be issued. In this invention, the reference value of the second comparator circuit 6 is changed in magnitude by the signal from the room temperature sensor 13, and stable operation can be obtained even when the temperature changes.

Furthermore, as described above, the electromotive force of the temperature sensor 2 becomes too low at low temperatures, and if the low output of the oxygen sensor 2 at the start of combustion is written into the storage section 4, the abnormality level will become even lower. In this invention, even if the oxygen sensor 2 detects oxygen in indoor air, it is installed near the combustor 1, and the operation of the oxygen sensor 2 is performed only after the ignition operation is performed and the combustion state of the combustor 1 reaches a steady state. Even when the room temperature is very low, when the combustion state reaches a steady state, the temperature near combustor 1 will have started to rise, and the temperature around oxygen sensor 2 will not be abnormally low, so it will not start. Electric power can be obtained reliably and stable operation is possible.

[Explanation of Examples]

The embodiment is a combustor safety device used in an up-and-down type oil combustor, and the main part uses a low-voltage driven microcomputer.

In the figure, 1 is a combustor, 14 is an ignition device that is operated after a wick raising operation by a wick up/down device 15;
When the core is lifted up, the power to the safety device is turned on. At the same time as the power is turned on, a battery check is performed, and if the power is abnormal, an automatic extinguishing operation is performed, and if normal, the wick is ignited by the ignition device 14 and combustion begins. Reference numeral 16 denotes a prepurge timer that counts the time until combustion in the combustor reaches steady combustion after ignition, and is set to 20 minutes in the wick type oil combustor of the embodiment. Further, the operation of the pre-purge timer 16 may be replaced by a temperature sensor or flame sensor that can confirm steady combustion.

2 is an oxygen sensor that detects the oxygen concentration in the indoor air
3 is a detection circuit that amplifies the electromotive force of the oxygen sensor 2 and converts it into a digital number so that it can be easily read by a computer;
7 is a main control circuit that compares and judges data and inputs and outputs signals to and from each section. When the pre-purge timer 16 counts up and the main control circuit 17 starts operating, first the output voltage of the oxygen sensor is read from the detection circuit 3, and the output voltage of the oxygen sensor 2 is determined by the third comparison circuit 10 to be below the usage limit value. At this time, it is determined that oxygen sensor 2 is defective and automatic fire extinguishing operation is performed.

18 is a scan timer for the detection circuit 3, which determines an interval for repeatedly reading the output voltage of the oxygen sensor 2 via the detection circuit 3 as needed. 4 is a storage unit for the output voltage of the oxygen sensor 2 in which the initial value is written; 12 is a reference value setting circuit for determining the oxygen deficiency state in indoor air; 1
3 is a room temperature sensor for making the reference value of the reference value setting circuit 12 temperature dependent; the reference value becomes smaller when the temperature is low in accordance with the characteristics of the oxygen sensor 2; If it suddenly occurs (when cold air blows into the combustor), change the reference value by temporarily increasing the value. In the embodiment, the scan timer 18 clocks in at 10 seconds]
When the output voltage of the oxygen sensor is increased, the output voltage of the oxygen sensor is read from the detection circuit 3 again, and then the previously stored output voltage of the detection circuit 3 is read from the storage section 4, and both data are compared by the first comparison circuit 5. When the read data from the oxygen sensor 2 indicates a higher concentration of oxygen than the storage section 4, the data in the storage section 4 is updated and the process returns to the scan timer 18.

Further, when the read data of the oxygen sensor 2 indicates a lower concentration of oxygen than the storage section 4, and it does not meet the reference value data, it is determined to be normal and the process returns to the scan timer 18. Further, in the event of an abnormality, the alarm 7 is activated and the automatic fire extinguishing system 11 is activated. At this time, the calorific value is small like a wick type oil combustor,
For burners that still have time to spare before abnormal combustion occurs, it may be possible to respond by reducing the amount of combustion.

When the combustor 1 lowers the wick manually by the wick lifting device 15 or by the automatic fire extinguishing device 11 while the combustor 1 is burning, the combustor engineer extinguishes the fire and the power to the safety device is cut off.

8 is a post-purge timer that starts counting when the automatic fire extinguishing device 11 is activated due to fire extinguishing by the wick up/down device 15 or extinguishing operation by the safety device; 9 is the data in the storage unit 4 which is activated when the post-purge timer 8 counts up. This is a memory clearing circuit for returning to the initial value, and in the Novostop purge timer 8 of the embodiment, the data in the memory unit 4 is held for one hour after the extinguishing operation, and then the data in the memory unit 4 is returned to the initial value. Therefore, while the post/merge timer 8 is counting, the core up/down device 15
When the combustion is started by operating the , the counting is interrupted and the data stored in the memory section 4 from the previous combustion is used as is.

[Explanation of effects]

As mentioned above, the data of the type of oxygen sensor that directly detects the oxygen concentration in indoor air varies depending on the measurement conditions, and the measured value of only around 21% to 18%, which is important for a combustor oxygen sensor, is directly measured in the combustor. It was almost impossible to use it as control data. This invention was able to directly measure the oxygen concentration in the air for the first time by examining how the data changes with the use of the combustor and confirming that the rate of change follows the change in oxygen concentration even with such an oxygen sensor. This is a completed combustor safety device that uses an oxygen sensor, and is a practical invention that enables oxygen sensor control in combustors other than Bunsen burners.

[Brief explanation of drawings]

1 is a block diagram showing an embodiment of the present invention, FIG. 2 is a flowchart of the operation, and FIG. 3 is a sectional view of the combustion device. 1... Combustor 2... Oxygen sensor
3...Detection circuit 4...Storage section 5.
...First comparison circuit 6 ...Second comparison circuit 7 ...Alarm device 8 ...Post purge timer 9 ...Memory clear circuit 10・・・・・・
...Third comparison circuit II...Automatic fire extinguishing system 1
2...Reference value setting circuit 13...Room temperature sensor wholesale (out 9 ~ 1 year old) 1 ¥1 Te 3

Claims (5)

[Claims] (1) An oxygen sensor 2 that changes the output voltage according to the oxygen concentration in the air in the room where the combustor 1 is installed, a detection circuit 3 that repeatedly reads the output voltage of the oxygen sensor 2 as needed, and A memory unit 4 stores the output, and a memory unit 4 is updated when the previously stored output of the detection circuit 3 is compared with the re-read output of the detection circuit 3 and the output is greater than the previously stored output. 1 comparator circuit 5 and a second comparator circuit 6 that compares the previously stored output of the detection circuit 3 with the re-read output and outputs an abnormal signal when the re-read output is lower than the reference value. A second comparison circuit 6 is provided.
A safety device for a combustor, which operates an alarm 7 or reduces the amount of combustion in the combustor, including extinguishing the fire, in response to an abnormal signal. (2) A post-purge timer 8 that operates when the combustor 1 is extinguished and a memory clearing circuit 9 for the memory unit 4 that is activated by the post-purge timer 8 are provided, and the memory unit 4 is set to a specific value after a certain period of time has elapsed during the extinguishing operation. 2. The combustor safety device according to claim 1, wherein the output of the storage unit 4 which has been previously stored is used for clearing and starting combustion during the operation of the post-purge timer 8. (3) Third comparison circuit 10 that compares the preset usage limit value of the oxygen sensor 2 and the output of the detection circuit 3
2. The combustor safety device according to claim 1, wherein the combustor 1 is provided with a combustor 1 and operates the automatic fire extinguishing device 11 of the combustor 1 when the output voltage of the oxygen sensor 2 at the start of use is below the usage limit value. (4) Reference value setting circuit 1 to be compared with second comparison circuit 6
2 is provided with a room temperature sensor 13 for detecting the temperature in the room in which the combustor 1 is installed, and the reference value of the second comparison circuit is varied by the output of the room temperature sensor 13.
Combustor safety devices as described in section. (5) The combustor safety device according to claim 1, wherein the oxygen sensor 2 is installed near the combustor 1, and the oxygen sensor 2 starts operating after the combustor 1 starts steady combustion.