JP2010175135A - Combustion device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a combustion device including a gas sensor capable of accurately sensing a CO concentration. <P>SOLUTION: Heat exchange with combustion gas generated by combustion of a combustion burner 2 is performed by a heat exchanger 5, and exhaust gas after the heat exchange is discharged via an air exhaust route 8. The gas sensor 9 is provided in the air exhaust route 8, and is stored within a sensing box 10 formed in the middle of the air exhaust route 8. The sensing box 10 is partitioned at the center in the longitudinal direction by a partition plate 11, and includes two chambers which are an upper separation chamber 12 and a lower sensing chamber 13. An inflow port 14 for the exhaust gas is opened at the center on a lateral wall of the separation chamber 12, and an exhaust port 15 and a communication port 16 smaller than the inflow port 14 and having the same size are formed at the centers of a top plate and the partition plate 11 of the separation chamber 12. The gas sensor 9 is positioned in the sensing chamber 13, and a gas venting small hole 17 is provided on the bottom plate of the sensing chamber 13. Thus, the CO concentration can be accurately detected. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a combustion apparatus that includes a gas sensor such as CO and detects incomplete combustion to stop combustion.

  Conventionally, this type has a stirring box in the exhaust path, a sensor box with a built-in CO sensor is provided on the side of the stirring box, and exhaust gas is introduced into the sensor box from almost the center of the stirring box. The inlet pipe, the inlet, and the outlet for discharging the exhaust gas are formed on the side surfaces, and the CO concentration is efficiently and accurately detected in the sensor box while suppressing the flow rate.

JP 2004-20155 A

  By the way, in this conventional apparatus, the CO sensor is generally used mainly for detecting CO, but also detects H2 (hydrogen) at the same time. Since this results in insufficient sensitivity when reacting only with CO, the lack of sensitivity can be compensated by detecting H2 generated simultaneously with CO during incomplete combustion. When the gas / petroleum combustion equipment causes incomplete combustion, it is possible to estimate the concentration of CO alone even in the exhaust gas in which CO and H2 are mixed by assuming that the ratio of CO and H2 in the exhaust gas is almost constant. However, in actuality, the ratio of CO and H2 in the exhaust gas is not stable and constant, and the ratio of CO and H2 changes due to differences in the cause of thermal power or incomplete combustion. However, there was a dangerous problem such as stopping even though the CO was not rising, or conversely not stopping even though the CO concentration was rising.

  In order to solve the above-described problems, the present invention particularly has a configuration in which the combustion gas generated by the combustion of the combustion burner is heat-exchanged by the heat exchanger, and the exhaust gas after the heat exchange is discharged through the exhaust path. The exhaust path is provided with a gas sensor, and the gas sensor is housed in a detection box formed in the middle of the exhaust path. The detection box is partitioned by a partition plate at the center in the vertical direction. And a detection chamber in the lower chamber, an exhaust gas inlet is opened in the center of the side wall of the separation chamber, and the center of the top plate and partition plate of the separation chamber is smaller than both of the inlets. Are formed with an exhaust port and a communication port of the same size, the gas sensor is located in the detection chamber, and a small hole for gas venting is provided in the bottom plate of the detection chamber.

  As described above, according to the present invention, CO and H2 in the exhaust gas can be easily separated from the difference in specific gravity, and the concentration of only CO can be detected reliably without erroneous detection, and incomplete combustion can be accurately detected. Therefore, there is no danger of incomplete combustion continuing, and it can be used safely for a long time.

The principal part block diagram of the combustion apparatus which shows one Embodiment of this invention. Explanatory drawing of the detection box. The block diagram of the principal part electric circuit. The flowchart of the principal part.

Next, an embodiment of the present invention will be described with reference to the drawings.
Reference numeral 1 denotes a water heater body as a combustion device, which is provided with a combustion chamber 4 having a gun-type combustion burner 2 and a combustion fan 3 attached downward at the upper end, and further, combustion burners in and outside the combustion chamber 4. A heat exchanger 5 for exchanging heat of the exhaust gas 2 with running water is provided.

  6 is a silencer that communicates the bottom of the combustion chamber 4 to one end and silences combustion noise. The other end is connected to an exhaust path 8 having a discharge port 7 at the top, and the exhaust gas from the combustion chamber 4 is silenced by the silencer 6. It is turned and discharged from the discharge port 7 by the blowing force of the combustion fan 3 through the exhaust path 8.

  A contact combustion type gas sensor 9 is provided in the exhaust path 8 and detects CO concentration in the exhaust gas to prevent incomplete combustion. The gas sensor 9 is housed in a detection box 10 formed in the middle of the exhaust path 8. ing.

  The detection box 10 is formed by dividing the center in the vertical direction by a partition plate 11 and forming two chambers of the same size vertically, with the upper chamber being a separation chamber 12 and the lower chamber being a detection chamber 13. An exhaust gas inlet 14 is opened in the center of the side wall on the exhaust path 8 side by a single hole, and the top plate of the separation chamber 12 and the central part of the partition plate 11 are smaller than the inlet 14 and both are the same size. The exhaust port 15 and the communication port 16 are formed as a single hole, and the gas sensor 9 is mounted in the detection chamber 13 on the wall surface of the exhaust path 8 forming one side wall. A small hole 17 for extraction is formed.

  Next, referring to the block diagram of the electric circuit shown in FIG. 3, an abnormality determination unit 19 and a timer 20 for timing are provided in the hot water supply control circuit 18 composed of a microcomputer of the water heater body 1, and a gas sensor is provided in the abnormality determination unit 19. 9, when a voltage is applied from the abnormality determination unit 19 to the gas sensor 9 at all times during energization, the gas sensor 9 returns an output to the abnormality determination unit 19. If this reference value is exceeded when compared with the set and stored reference value, the timer 20 starts counting and determines that abnormal combustion has occurred for 10 seconds or longer, and the abnormality determination unit 19 performs combustion control. A signal is output to the section 21 and the combustion of the combustion burner 2 is stopped.

Next, the operation of this embodiment will be described with reference to the flowchart shown in FIG. 4. When the faucet is now opened and running water is generated and the combustion control unit 21 is energized, the combustion burner 2 starts combustion (step 22). ).
Then, the heat exchanger 5 is heated by the combustion in the combustion chamber 4, and the flowing water flowing through the heat exchanger 5 is warm water and is appropriately supplied with hot water.

  On the other hand, the gas sensor 9 starts to detect the CO concentration. In general, exhaust gas components are mainly N2 (molecular weight 28), CO2 (molecular weight 44), O2 (molecular weight 32), and these volume ratios account for 90% or more. , CO and H2 are very small, less than 0.01% during normal combustion, and the molecular weight of CO is 28, which is almost the same weight as N2 which is the most component in the exhaust gas. Dispersed almost uniformly inside. However, the molecular weight of H2 is 2, which is much lighter than other gas components, so it is likely to rise, and if it exists in a space where there is no flow, H2 will collect above the space. Using this behavior, CO and H2 can be separated in the separation chamber 12 and the influence of H2 can be minimized.

  Accordingly, detection of the CO concentration is started in step 23, and the exhaust gas flows into the separation chamber 12 from the inlet 14 of the detection box 10, but the separation chamber 12 has a smaller exhaust port 15 than the inlet 14, so that the static pressure is low. The exhaust gas that has flowed into the separation chamber 12 does not flow in one direction, but diffuses in the separation chamber 12 and backflows to the exhaust port 15 and the inflow port 14 and returns to the exhaust path 8, and the exhaust gas passes through the communication port 16. It also diffuses into the detection chamber 13 and reacts with the gas sensor 9. At this time, since H2 in the exhaust gas diffused in the separation chamber 12 is lighter than other exhaust gas components, most of the H2 goes out from the exhaust port 15, and the H2 flowing into the detection chamber 13 is always stable in a small amount. Even if the ratio of CO and H2 in the exhaust gas fluctuates greatly, the amount of H2 that reacts with the gas sensor 9 can be attenuated, and it is difficult to be affected by fluctuations in H2 concentration. It can be built.

  The relatively heavy gas components N2 (molecular weight 28), CO2 (molecular weight 44), and O2 (molecular weight 32) in the exhaust gas flowing into the separation chamber 12 are directly applied to the detection chamber 13 through the communication port 16 with their weights. Although it falls, it passes through the exhaust hole 8 from the degassing small hole 17 on the bottom plate of the detection chamber 13, so that there is no stagnation due to heavy gas components in the detection chamber 13 and it can always be kept clean and in good condition. It is.

  Next, the process proceeds to step 24, where it is determined whether the CO concentration value X detected by the gas sensor 9 is the reference value A, here 1000 ppm or more. If NO, there is no abnormality, so the process proceeds to step 25 to determine whether the combustion is stopped. 26, the combustion end state is maintained as it is, and NO is the combustion continuation state, so that the process returns to step 23 and the CO concentration is detected again. If the CO concentration value X is 1000 ppm or more in step 24 and YES, step In step 27, the timer 20 starts counting and determines whether or not the abnormality detection time continues for T of 10 seconds or more in this case. If NO, the process returns to step 23. The combustion is stopped and an abnormal state in the incomplete combustion state is notified.

  Therefore, it is possible to accurately detect the CO concentration in the exhaust gas by utilizing the difference in specific gravity of the gas components, and to reliably prevent the danger caused by incomplete combustion. If the cause is investigated and the lock is made until the repair is completed, the safety is further improved.

2 Combustion burner 5 Heat exchanger 8 Exhaust path 9 Gas sensor 10 Detection box 11 Partition plate 12 Separation chamber 13 Detection chamber 14 Inlet 15 Exhaust port 16 Communication port 17 Small hole for degassing

Claims (1)

  Combustion gas generated by the combustion of the combustion burner is heat-exchanged by a heat exchanger, and the exhaust gas after heat exchange is discharged through an exhaust path. The exhaust path is provided with a gas sensor, The detection box is housed in a detection box formed in the middle of the exhaust path. The detection box is partitioned by a partition plate at the center in the vertical direction, and is composed of an upper chamber separation chamber and a lower chamber detection chamber. An exhaust gas inlet is opened in the center of the side wall, and an exhaust port and a communication port that are smaller than the inlet and both have the same size are formed in the center of the top plate and the partition plate of the separation chamber. A combustion apparatus characterized in that the gas sensor is positioned in a detection chamber, and a small hole for venting is provided in a bottom plate of the detection chamber.

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