JP5854547B2 - boiler - Google Patents

Description

  The present invention relates to a boiler that detects scale adhesion in a water pipe by detecting the water pipe temperature.

  As described in Japanese Patent Application Laid-Open No. 2009-92278, a temperature sensor is provided at a predetermined location of a water pipe constituting a boiler, and scale adhesion in the water pipe is determined by detecting the water pipe temperature. Yes. In the boiler, the temperature of the boiler water is raised by heating the water pipe from the outside by the heat generated by the combustion device and transferring the heat to the boiler water in the water pipe. If the scale adheres to the inner side of the water pipe, heat transfer from the water pipe to the boiler water will deteriorate, leading to a shortened boiler life due to a rise in water pipe temperature and a decrease in boiler efficiency. Since adhesion of the scale can be determined by detecting an increase in the water tube temperature, the adhesion of the scale is determined by detecting the water tube temperature as described above.

  As described in Japanese Patent Application Laid-Open No. 2009-92278, in order to accurately detect the amount of scale attached, it is necessary to provide a temperature measuring device at a portion where the scale is easily attached. And in invention of Unexamined-Japanese-Patent No. 2009-92278, by providing a temperature sensor in the boiling start part of the water in a water pipe, or the high heat load part of the water pipe, the amount of scale adhesion on the inner surface of a water pipe is grasped correctly. It is said that you can. However, scale adhesion does not necessarily increase at the above-mentioned locations, and there are cases in which the amount of scale adhesion increases at a position near the air / water surface higher than this position. Therefore, in order to increase the accuracy of scale detection, it is necessary to detect the water tube temperature at a more appropriate location.

JP 2009-92278 A

  The problem to be solved by the present invention is to increase the detection accuracy in a boiler that determines the scale adhesion in the water pipe by detecting the water pipe temperature so that the scale adhesion can be judged at an earlier stage. It is in.

The invention according to claim 1 is a once-through boiler in which a water level is set in the middle of a water pipe installed in a vertical direction, and when the boiler is burned, the lower part in the water pipe mainly composed of boiler water and steam A temperature sensor that detects the temperature of the water pipe is provided in the area where the air / water surface, which is the boundary with the upper part of the main water pipe, is formed. If the water level is controlled so that the area where the air-water surface is formed is different depending on the combustion amount, the water pipe temperature is higher than the reference value and the scale adhesion is determined. A temperature sensor is provided in accordance with a plurality of air-water surface formation regions that differ depending on the combustion amount.
The invention according to claim 2 is that, in the boiler, when the water level in the boiler is controlled to be high, the scale adheres based on the water pipe temperature detected by the temperature sensor provided in accordance with the air / water surface area at the high water level. When the water level in the boiler is controlled to be low, the scale adhesion is determined based on the water pipe temperature detected by the temperature sensor provided in accordance with the air / water surface area at the low water level. .

  Since the temperature of the water pipe is detected at the portion where the scale adheres most, it is possible to accurately detect the scale adherence.

Partial sectional view in a state where the set water level of a boiler implementing the present invention is increased Partial sectional view in a state where the set water level of a boiler implementing the present invention is lowered Explanatory drawing of temperature sensor installation status in a boiler implementing the present invention

  An embodiment of the present invention will be described with reference to the drawings. 1 and 2 are partial cross-sectional views of a boiler according to an embodiment of the present invention. FIG. 1 shows a case where the water level in the boiler is controlled high, and FIG. 2 shows a case where the water level is controlled low. FIG. 3 is an explanatory view of a temperature sensor installation state in a boiler implementing the present invention.

  The boiler 1 has a configuration in which a combustion chamber 2 installed in the center is surrounded by a large number of vertical water pipes 3 and a combustion device 4 is provided in the upper portion of the combustion chamber. The combustion device 4 generates a flame downward toward the combustion chamber 2 and heats the water tube 3 with the heat of the flame. The water pipe 3 is connected to an annular header provided at the upper part and the lower part, water is supplied to the lower header 7, steam is generated by heating boiler water in the water pipe part, and the steam is supplied to the upper header 8. Remove after gathering. The water pipes connect adjacent water pipes with fins 5 to form an annular inner water pipe row and an outer water pipe row, and a combustion gas passage 6 through which combustion gas passes is provided between the inner and outer water tube rows.

  The combustion gas generated by the combustion by the combustion device 4 heats the water pipe 3 when flowing along the surface of the water pipe around the combustion chamber. In the case of the structure in which the water tubes are arranged in two rows in a ring shape, the combustion gas generated by the combustion device 4 enters the combustion gas passage 6 from the combustion chamber 2 and the combustion gas passage 6 formed between the inner water tube row and the outer water tube row. The water pipe 3 is heated by letting the combustion gas pass through, and the exhaust gas whose temperature has decreased by exchanging heat with the water pipe is discharged out of the boiler. In the case of the inner water tube row, one surface faces the combustion chamber 2 and the other surface faces the combustion gas passage 6, so that heating is performed from both surfaces. In the case of the outer water tube row, one surface faces the combustion gas passage 6, but the other surface is heated only from one surface because the combustion gas does not pass therethrough.

  Since the boiler water boiled from the vertical water pipe portion flows into the upper header 8 together with the steam, the steam and boiler water are separated by the steam / water separator 9 connected to the upper header 8 by a connecting pipe. The steam separated by the steam separator 9 is taken out from the top of the steam separator, and the boiler water is returned to the lower header 7 of the boiler through a return water pipe connecting the bottom of the steam separator 9 and the lower header 7.

  The combustion device 4 performs combustion control at three positions of high combustion, low combustion, and combustion stop, and determines the amount of combustion according to the value of the steam pressure supplied from the boiler. The operation control device 10 that controls the operation of the combustion device receives a signal from the pressure detection device 11 that detects the steam pressure value of the boiler, determines the combustion amount, and fuel and combustion air so that the determined combustion amount is obtained. Supply. In the operation control device 10, when the steam pressure value is in the low category, the combustion amount is set to high combustion. When the steam pressure value becomes higher by one step from that state, the combustion amount is reduced to reduce the combustion, and when the steam pressure value exceeds the upper limit value of the control range, the combustion is stopped.

  The water level in the boiler is detected by a water level detection device 15 provided outside the can body. The water level detection device 15 is provided with a plurality of electrode rods having different heights at the lower ends, and the water level is detected by examining which electrode rods are in contact with water. When the water level detected by the water level detection device 15 falls to the water supply start water level, the operation control device 10 operates the water supply pump to supply water to the boiler, and stops the water supply when the water level rises to the water supply stop water level. The water level adjustment range is set high when the combustion amount of the boiler is small, and is set low when the combustion amount of the boiler is large. For example, the water level range at low combustion is between a and b in the figure, and the water level range at high combustion is between b and c in the figure.

  Boiling of boiler water occurs in a water pipe in which boiler water is boiling. Even when the water level of the boiler is set in the middle of the water pipe, the boiler water is heated up in the water pipe. Is prevented. The amount of boiler water boiling varies depending on the amount of boiler combustion. When the amount of combustion of the boiler is small, the amount of boiling of the boiler water is small, and when the amount of combustion is large, the amount of boiling of the boiler water is increased. Therefore, when the amount of boiler water boiling is small, there is a risk that the upper part of the water pipe will be overheated if the set water level of the boiler is low. If the boiler water is taken out together with the steam, the dryness of the steam may be reduced. Therefore, the water level in the boiler is increased when the combustion amount of the boiler is small, and the water level is decreased when the combustion amount is large. By doing in this way, even if the amount of boiling in a water pipe changes with combustion amounts, water pipe overheating and the fall of steam dryness can be prevented.

  Detection of scale adhesion is performed by a temperature sensor 12 that detects the water tube temperature and a scale determination unit 13 that determines the presence or absence of scale adhesion based on the detected water tube temperature. The scale determination unit 13 is installed in the operation control apparatus 10 of the boiler. Keep it. The water pipe 3 is provided with a temperature sensor 12 for detecting the water pipe temperature, and information on the water pipe temperature detected by the temperature sensor 12 is output to the scale determination unit 13 of the operation control device 10.

  As shown in FIG. 3, the temperature sensor 12 has a structure in which a temperature sensing portion is inserted into a portion facing the combustion gas passage 6 of the water tube from the outside of the outer water tube row, and a portion facing the combustion gas passage of the water tube. Is provided with a mounting base 14 having a hole for inserting a rod-shaped temperature sensing portion. The temperature sensor 12 is attached by penetrating the fin 5 connecting the outer water pipe, and the temperature of the water pipe can be detected by inserting the temperature sensing part of the temperature sensor 12 into the hole of the mounting base 14. To do. The temperature sensor 12 is installed in a height range where an air-water surface is formed in the water pipe during boiler combustion.

  When burning in a boiler, the temperature in the lower part of the water pipe is low, and the temperature increases as it goes up. When the temperature of the boiler water reaches a temperature at which boiling begins, bubbles start to be generated in the water, and when the temperature rises further, the bubbles increase, so the ratio of bubbles increases above the boiling start point. . When the number of air bubbles increases, steam is mainly used from a certain point. The dry state due to is mixed in intricately. In the water pipe near the air / water surface, the concentration of boiler water proceeds and the concentration of scale components increases. And in this part, since the area | region where wetting and drying is repeated is formed, a scale tends to precipitate.

  The scale determination unit 13 that determines scale adhesion makes a determination based on the water tube temperature value detected by the temperature sensor 12. If the scale adheres to the inside of the water pipe, the heat transfer from the water pipe to the boiler water is hindered because the scale has a significantly lower heat transferability than the metallic water pipe. Since the water pipe is heated from the outside by the combustion gas and cooled from the inside by the boiler water, if the heat transfer from the water pipe to the boiler water decreases, the temperature of the water pipe will not decrease, and the water pipe temperature will rise. Therefore, when the water tube temperature is lower than the reference value, there is no scale adhesion, and when the water tube temperature is higher than the reference value, it can be determined that there is scale adhesion.

  By installing the temperature sensor 12 in the area of the air / water surface where the scale adheres more, it becomes possible to detect the scale quickly when the scale adheres. In a boiler in which different water levels are set according to the amount of combustion, a plurality of air-water level ranges may be formed. In that case, a plurality of temperature sensors 12 are installed in accordance with the plurality of air-water surface ranges. By setting it, the detection accuracy of scale adhesion can be made higher. At that time, when the water level is high, the scale adhesion is determined based on the water pipe temperature detected by the temperature sensor 12 installed at a high position, and when the water level is low, By determining the scale adhesion based on the water tube temperature detected by the temperature sensor 12 installed at a low position, it is possible to improve the detection accuracy of the scale adhesion.

  In boilers, there are boilers with high combustion and boilers with low combustion depending on the installation environment.Boilers with high combustion have a large scale in the air-water surface area at high combustion, and boilers with low combustion have low combustion. Scale increases in the water surface area. However, it is difficult to specify the combustion state of the boiler depending on the installation environment. Therefore, even if a plurality of temperature sensors 12 are installed in accordance with the air / water surface range that varies depending on the combustion amount, it may not be known in advance which temperature sensor 12 value is optimal for determining the scale adhesion. There are many.

  Even in that case, the amount of scale that adheres to the air / water surface during high combustion increases in boilers that burn for a long time with high combustion, and the amount of scale that adheres to the air / water surface during low combustion for boilers that burn for a long time with low combustion Will increase. Therefore, when burning at high combustion, the water pipe temperature is detected in the air / water surface range at high combustion, and when burning at low combustion, the water pipe temperature is detected at the air / water surface range at low combustion. By doing so, it is possible to make a judgment according to the operating state and to perform highly reliable scale detection.

  The present invention is not limited to the embodiments described above, and many modifications can be made by those having ordinary knowledge in the art within the technical idea of the present invention.

1 boiler
2 Combustion chamber
3 Water pipe 4 Combustion device 5 Fin 6 Combustion gas passage 7 Lower header 8 Upper header 9 Air / water separator 10 Operation control device 11 Pressure detection device 12 Temperature sensor 13 Scale judgment unit
14 Mounting base 15 Water level detection device

Claims (2)

A once-through boiler in which the water level is set in the middle of a water pipe installed in the vertical direction, and when the boiler is burned, the boundary between the lower part in the water pipe mainly composed of boiler water and the upper part in the water pipe mainly composed of steam A temperature sensor that detects the temperature of the water pipe is provided in the area where the air / water surface is formed, and has a scale judgment unit that judges the presence or absence of scale adhesion based on the water pipe temperature detected by the temperature sensor. If the water level is controlled so that the area where the air / water surface is formed differs depending on the combustion amount, the formation of multiple air / water surfaces that differ depending on the combustion amount is determined. A boiler comprising a temperature sensor according to a region . The boiler according to claim 1 , wherein when the water level in the boiler is controlled to be high, adhesion of scale is determined based on a water pipe temperature detected by a temperature sensor provided in accordance with an air-water surface region at a high water level. A boiler characterized in that, when the internal water level is controlled to be low, scale adhesion is determined based on a water pipe temperature detected by a temperature sensor provided in accordance with an air-water surface region at a low water level.

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