Boiler

Abstract

To provide a boiler capable of controlling a water level according to an electrical conductivity of boiler water.SOLUTION: A boiler comprises: a boiler body 2 that generates steam; a steam extraction unit 3 that extracts the generated steam to the outside of the boiler body 2; a separator 4 that is connected to the steam extraction unit 3, and separates the steam extracted by the steam extraction unit 3 into water and steam; and a water level detection unit 5 that detects a water level of the boiler body 2. The water level detection unit has a communication pipe that communicates with the inside of the steam extraction unit.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a boiler. [Background technology]

[0002] Conventionally, when controlling the water level of a boiler, a water level detection tube is provided connected to the upper header and lower header inside the boiler body, and the water level detected inside the water level detection tube is used to estimate the boiler water level inside the boiler body, thereby supplying water to the boiler body (for example, Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2016-164480 A Summary of the Invention [Problem to be solved by the invention]

[0004] Here, when the electrical conductivity of the boiler water in the boiler body becomes high due to concentration or the like (high EC), the viscosity increases and bubbling becomes intense. This makes it easier for water to be carried out together with the steam, and there is a risk that steam with low dryness will be supplied (carry-over). Therefore, when the electrical conductivity of the boiler water is high, it is necessary to lower the boiler water level compared to when the electrical conductivity is low (low EC). In conventional water level control, an electrical conductivity meter is installed and water is supplied according to changes in the electrical conductivity measured by the electrical conductivity meter, thereby controlling the water level while taking the electrical conductivity into consideration. However, there was a risk that the water level control according to the electrical conductivity would not be performed appropriately due to the electrical conductivity meter breaking down or the like.

[0005] The present invention has been devised in view of the above circumstances, and an object of the present invention is to provide a boiler capable of controlling the water level in accordance with the electrical conductivity of the boiler water. [Means for solving the problem]

[0006] In order to achieve the above-mentioned object, the boiler of the present invention comprises a boiler body that generates steam, a steam extraction section that extracts the generated steam to the outside of the boiler body, a separator connected to the steam extraction section that separates the steam extracted by the steam extraction section into steam and water, and a water level detection section that detects the water level in the boiler body, and the water level detection section has a communicating pipe that communicates with the inside of the steam extraction section.

[0007] According to the above configuration, by providing the steam extraction part, pressure loss occurs when steam is extracted from the boiler body to the steam extraction part. In addition, the viscosity of boiler water increases with an increase in electrical conductivity, so the pressure loss also varies with the change in electrical conductivity. As a result, pressure according to the change in electrical conductivity is applied to the water level detection part communicated with the steam extraction part via the communication pipe. As a result, it becomes possible to control the water level according to the electrical conductivity of the boiler water.

[0008] Preferably, the steam outlet is disposed above the boiler body.

[0009] According to the above configuration, since the steam outlet is disposed above the boiler body, the steam in the boiler body can be collected at the steam outlet and then flowed into the separator. As a result, it is possible to prevent water from being carried away to the separator together with the steam, while generating pressure loss.

[0010] Preferably, the communication pipe communicates with the inside of the steam outlet portion at a position where a pressure loss after the generated steam is taken out from the boiler body falls within a predetermined range.

[0011] According to the above configuration, the communication pipe communicates with the steam outlet at a position where the pressure loss is within a predetermined range. This makes it possible to prevent the water level from being controlled at a low water level relative to the boiler water's electrical conductivity because the pressure loss is smaller than the predetermined range, or the water level from being controlled at a high water level relative to the boiler water's electrical conductivity because the pressure loss is larger than the predetermined range. As a result, the water level can be controlled at an appropriate water level according to the boiler water's electrical conductivity. [Brief description of the drawings]

[0012] [Figure 1] FIG. 2 is a diagram for explaining a schematic configuration of a boiler. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0013] <Overview of the configuration> DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, an embodiment of the present invention will be described with reference to the drawings. First, a schematic configuration of a boiler according to the present embodiment will be described with reference to FIG.

[0014] As shown in Fig. 1, the boiler 1 includes a boiler body 2 that burns fuel to generate steam, a steam extraction pipe (steam extraction section) 3 that extracts the steam generated in the boiler body 2 to the outside, a separator (steam-water separator) 4, a water level detection section 5 that detects the water level in the boiler body 2, and a water supply line 7 that supplies water to the boiler body 2. The boiler 1 also includes, as combustion and blowing equipment, a blower (not shown) that sends air into the combustion chamber of the boiler body 2 through an air supply passage, an exhaust passage (not shown) that draws out exhaust gas from the boiler body 2, and a fuel supply line (not shown) that supplies fuel to the boiler body 2. The fuel is not limited to a liquid such as oil, and may be a gas such as gas.

[0015] The operation and behavior of the boiler 1 is controlled by a control device realized by a computer including an internal memory, timer, and calculation processing unit. The combustion amount of the boiler 1 is adjusted continuously or stepwise by adjusting the flow rate of air sent to the boiler body 2 and the flow rate of fuel supplied by the control device.

[0016] The boiler body 2 is formed in a substantially cylindrical shape, and includes therein a burner, a plurality of water tubes 23, an upper header 21, and a lower header 22. The plurality of water tubes 23 are housed inside the boiler body 2, and are erected at predetermined intervals in the circumferential direction of the boiler body 2. As a result, a combustion chamber is formed in the substantially central portion of the boiler body 2.

[0017] A burner is provided above the combustion chamber, and the burner heats boiler water introduced into the water tubes 23 to generate steam. The burner is also connected to a fuel tank via a fuel supply line.

[0018] The lower header 22 is provided at the bottom of the boiler body 2 and is connected to the lower parts of the multiple water tubes 23. The lower header 22 is connected to the water supply line 7. Water supplied from the water supply line 7 through the lower header 22 is heated in the water tubes 23.

[0019] The upper header 21 is provided at the top of the boiler body 2 and is connected to the upper parts of the multiple water tubes 23. Steam generated in the multiple water tubes 23 is collected into the steam extraction pipe 3 via the upper header 21. The steam collected in the steam extraction pipe 3 is led to the separator 4. A steam pipe (not shown) for taking out steam is connected to the top of the separator 4, and the steam separated by the separator 4 is taken out from the steam pipe. In addition, a downcomer pipe 41 is provided connecting the lower part of the separator 4 and the lower header 22, and the water separated by the separator 4 is returned from the downcomer pipe 41 through the lower header 22 to the boiler body 2.

[0020] The steam extraction pipe 3 is provided on the upper part of the boiler body 2, and extracts the steam generated in the boiler body 2 to the outside of the boiler body 2. The steam extraction pipe 3 collects the steam generated in the boiler body 2 and leads the collected steam to the separator 4. As a result, the steam generated in the boiler body 2 is separated into steam and water in the separator 4 through the steam extraction pipe 3. As a result, steam with a high dryness is supplied to the destination of use. The steam extraction pipe 3 is not limited to a tubular one, and may be formed in a box shape. The boiler body 2 and the steam extraction pipe 3 are connected by three connecting pipes 31. The number of connecting pipes 31 is not limited to three, and may be, for example, two or four.

[0021] The water level detection unit 5 has an upper portion communicating (connected) with the inside of the steam extraction pipe 3 via the communication pipe 6. The lower portion of the water level detection unit 5 communicates (connected) with the lower portion (lower header 22) of the boiler body 2. The connection position of the communication pipe 6, the position, length, and number of the connection pipes 31, and the shape and dimensions of the steam extraction pipe 3 are set so that when the electric conductivity of the boiler water is high (high EC (predetermined electric conductivity)), the "pressure loss Δp" that occurs from when the steam generated in the boiler body 2 is taken out from the boiler body 2 via the connection pipe 31 until it reaches the connection position of the communication pipe 6 is within a predetermined range. The predetermined electric conductivity may be a relatively high value, and is, for example, the electric conductivity when the water is blown off in order to maintain appropriate water quality. Moreover, the pressure loss Δp occurring from when the steam generated in the boiler body 2 is taken out from the boiler body 2 through the connecting pipe 31 until it reaches the connecting position of the communicating pipe 6 is, for example, the difference Δp between the pressure p1 of the steam when it flows into the connecting pipe 31 and the pressure p2 of the steam when it reaches the connecting position of the communicating pipe 6. The pressure loss Δp in the predetermined range will be described later in detail. Note that the pressure loss Δp at high EC may be adjusted to be within a predetermined range by providing a pressure reducing member such as an orifice in the connecting pipe 31.

[0022] The water level detection unit 5 includes a water level control tube 51 formed of a conductive metal, and electrode rods 52 of different lengths. The water level detection unit 5 is configured to detect the water level in the water level control tube 51 in stages by detecting the water level with the tip of the electrode rod 52. For example, an L rod 52L and an S rod 52S that is shorter than the L rod 52L and detects a water level higher than the L rod 52L are provided, and when the combustion amount is low, it is determined that the water level in the boiler main body 2 has dropped below a predetermined position when the water level is no longer detected by the S rod 52S, and when the combustion amount is high, it is determined that the water level in the boiler main body 2 has dropped below a predetermined position when the water level is no longer detected by the L rod 52L.

[0023] When the water level is no longer detected by the electrode rods 52 (for example, after a predetermined time (e.g., 5 seconds) has elapsed since the water level was no longer detected), the control device controls the supply of water to the boiler body 2. The water level detected by the electrode rods 52 is determined to be, for example, the ideal dryness limit water level or a water level lower than that level when the boiler water is new water (when EC is lowest). The dryness limit water level is the upper limit water level of the boiler water in the boiler body 2 for maintaining steam of a desired dryness. The number of electrode rods 52 is not limited to two, the L rod 52L and the S rod 52S, but may be any number required according to the combustion stage to be controlled, etc.

[0024] In addition, pressure p from the steam extraction pipe 3 is applied to the water level control cylinder 51 through the communication pipe 6. The water level in the water level control cylinder 51 fluctuates according to the pressure p from the steam extraction pipe 3. The pressure p from the steam extraction pipe 3 fluctuates according to the electrical conductivity of the boiler water, as described later.

[0025] Here, when the electrical conductivity of the boiler water in the boiler body 2 becomes high (high EC) due to concentration or the like, the viscosity increases and bubbling becomes intense. This makes it easier for water to be carried away with the steam, and there is a risk that steam with low dryness will be supplied. Therefore, it is necessary to keep the water level in the boiler body 2 lower than when the electrical conductivity is low (low EC).

[0026] Furthermore, the boiler water has a higher electrical conductivity and a higher viscosity, which increases the pressure of the steam generated from the boiler body 2. Therefore, when the electrical conductivity is high (high EC), the pressure loss Δp when steam is extracted from the boiler body 2 to the steam extraction pipe 3 becomes larger than when the electrical conductivity is low (low EC). Therefore, in this embodiment, the pressure loss caused by the change in the electrical conductivity of the boiler water is utilized to vary the water level in the water level control tube 51 detected by the water level detection unit 5 according to the electrical conductivity of the boiler water.

[0027] In this embodiment, when the boiler water has a low electrical conductivity (low EC), the pressure loss Δp when steam is taken out from the boiler body 2 to the steam take-out pipe 3 is smaller than that when the boiler water has a high EC. As described above, the electrode rod 52 can detect whether the boiler water has reached the ideal dryness limit water level or a water level lower than the ideal dryness limit water level when the boiler water is new (when the EC is the lowest). This makes it possible to supply water based on the detection result of the water level detection unit 5 so that the boiler water has an appropriate water level according to the fact that the boiler water is new.

[0028] Thereafter, the electrical conductivity of the boiler water gradually increases in response to the operation of the boiler 1, and the pressure loss Δp also gradually increases, increasing the difference between the pressure inside the boiler body 2 and the pressure at the connection position of the communicating tube 6. As a result, even if the boiler water is new and the water level is not detected by the water level detection unit 5, the pressure at the connection position of the communicating tube 6 becomes smaller relative to the pressure inside the boiler body 2 as the electrical conductivity increases, so that the water level in the water level control tube 51 becomes higher than the actual water level of the boiler water and can be detected by the electrode rod 52.

[0029] Furthermore, when the electrical conductivity of the boiler water becomes higher, i.e., higher EC, the pressure loss Δp increases when steam is taken out from the boiler body 2 to the steam take-out pipe 3, and the difference between the pressure inside the boiler body 2 and the pressure at the connection position of the communicating pipe 6 becomes larger. As a result, even if the water level is not detected by the water level detection unit 5 when the electrical conductivity of the boiler water is low, the pressure at the connection position of the communicating pipe 6 becomes smaller compared to the pressure inside the boiler body 2 when the EC is high, so that the water level in the water level control tube 51 becomes higher and can be detected by the electrode rod 52.

[0030] In this way, water can be supplied based on the detection result of the water level detection unit 5 so that the boiler water level becomes appropriate in response to the increase in the electric conductivity of the boiler water. That is, the pressure applied to the water level control tube 51 through the communication pipe 6 decreases in response to the increase in the electric conductivity of the boiler water, so that the water level in the water level control tube 51 gradually becomes higher than the actual water level in the boiler body 2. As a result, when the electric conductivity of the boiler water increases and it is necessary to lower the water level in the boiler body 2, the water level detection unit 5 detects a water level higher than the actual water level in the boiler body 2, so that excessive water supply can be suppressed. In addition, in the water level control in this embodiment, the water level can be controlled in response to the water level and electric conductivity in the boiler body 2 without measuring the electric conductivity using an electric conductivity meter or the like, so that steam with a high dryness can be supplied without directly measuring the electric conductivity.

[0031] The communicating pipe 6, which communicates the inside of the steam extraction pipe 3 with the water level detection unit 5, communicates with the inside of the steam extraction pipe 3 at a position where the pressure loss Δp from when steam is extracted from the boiler body 2 when the boiler water has a high EC is within a predetermined range (for example, 150 mmAq to 250 mmAq). In other words, the communicating pipe 6 is communicated at a position where the pressure loss Δp from when the steam generated from the boiler body 2 is extracted to the steam extraction pipe 3 to when it reaches the communicating pipe 6 is within a predetermined range. Note that the position where the communicating pipe 6 is communicated may be, for example, the upper side or side of the steam extraction pipe 3 in the vertical direction.

[0032] Here, the predetermined range of the pressure loss Δp at high EC in this embodiment will be described. The upper and lower limit values ​​of the predetermined range of the pressure loss Δp at high EC are determined, for example, based on the ideal dryness limit water level in the boiler body 2 at high EC. The lower limit value of the predetermined range is the pressure loss that is detected by the water level detection unit 5 when the highest water level in the range of the ideal dryness limit water level is reached at high EC. On the other hand, the upper limit value of the predetermined range is the pressure loss that is detected by the water level detection unit 5 when the lowest water level in the range of the ideal dryness limit water level is reached at high EC. The predetermined range is determined according to the size and shape of the boiler, and therefore differs for each boiler. The predetermined range may be determined based on other parameters in addition to or instead of the dryness limit water level at high EC, and may be determined based on, for example, the ratio to the water level not including the pressure loss.

[0033] This makes it possible to prevent the following problems from occurring: the pressure applied inside the water level control cylinder 51 becomes too large because the pressure loss Δp is smaller than the specified range, causing water level control to be performed at a water level lower than appropriate for the boiler water's electrical conductivity; or the pressure applied inside the water level control cylinder 51 becomes too small because the pressure loss Δp is larger than the specified range, causing water level control to be performed at a water level higher than appropriate for the boiler water's electrical conductivity.

[0034] As described above, in this embodiment, the steam extraction pipe 3 is provided to extract the steam generated from the boiler body 2 to the outside of the boiler body 2, and thus a pressure loss Δp occurs when the steam is extracted from the boiler body 2. In addition, since the viscosity of boiler water increases with an increase in electrical conductivity, the pressure loss Δp also varies with the change in electrical conductivity. As a result, pressure according to the change in electrical conductivity is applied to the water level detection unit 5, which is connected to the steam extraction pipe 3, via the communication pipe 6. As a result, the water level can be controlled according to the electrical conductivity of the boiler water.

[0035] In addition, since the steam extraction pipe 3 is disposed above the boiler body 2, the steam in the boiler body 2 can be collected by the steam extraction pipe 3 and then flowed into the separator 4. As a result, it is possible to suppress water from being carried away to the separator 4 together with the steam, while generating a pressure loss.

[0036] Furthermore, the communicating pipe 6 communicates with the inside of the steam extraction pipe 3 at a position where the pressure loss Δp after the steam is extracted from the boiler body 2 is within a predetermined range. This makes it possible to prevent water level control from being performed at a water level lower than the appropriate water level for the boiler water's electrical conductivity because the pressure loss Δp is smaller than the predetermined range, or to prevent water level control from being performed at a water level higher than the appropriate water level for the boiler water's electrical conductivity because the pressure loss Δp is larger than the predetermined range. As a result, water level control becomes possible at an appropriate water level according to the boiler water's electrical conductivity.

[0037] Therefore, in the boiler 1 of this embodiment, as the electrical conductivity of the boiler water increases, the pressure loss Δp after the steam is taken out of the boiler body 2 also increases, and as the pressure loss Δp increases, the water level in the water level control cylinder 51 becomes higher than the water level in the boiler body 2. In other words, the steam take-out pipe 3, the connection pipe 31, and the communication pipe 6 are provided so that the water level in the water level control cylinder 51 is detected as higher than the water level in the boiler body 2 according to the pressure loss Δp when the EC is high, and therefore the water level can be controlled at an appropriate water level even when the boiler water has a high EC.

[0038] The present invention is not limited to the above-described embodiment, and various modifications and applications are possible. Modifications of the above-described embodiment that can be applied to the present invention will be described below.

[0039] In the above embodiment, an example has been described in which the steam extraction pipe 3 is installed above the boiler body 2. However, the present invention is not limited to this, and the steam extraction pipe 3 may be installed to the side of the boiler body 2. Even in this case, it is sufficient to create a pressure loss Δp so that the water level in the water level control tube 51 is detected to be higher than the water level in the boiler body 2 according to the pressure loss Δp when steam is extracted from the boiler body 2 to the steam extraction pipe 3 when the boiler water has a high EC, thereby enabling water level control according to the ideal dryness limit water level for the high EC.

[0040] In the above embodiment, an example has been described in which the water level detected by the electrode rod 52 is set to the ideal dryness limit water level or a water level lower than that level when the boiler water is new water (when EC is lowest). However, the invention is not limited to this, and the water level may be set so that the ideal dryness limit water level or a water level lower than that level is detected at an average EC when the boiler 1 is operated. Alternatively, the water level may be set so that the ideal dryness limit water level or a water level lower than that level is detected when the boiler water has a high electrical conductivity (high EC (predetermined electrical conductivity)).

[0041] In the above embodiment, the electrode rod of the water level detection unit 5 is exemplified as one that detects the water level at the tip of the electrode rod. However, this is not limiting, and for example, an insulating coating that acts as a dielectric may be formed on the surface of the electrode rod that detects the water level, and the part of the electrode rod that contacts the water in the water level control cylinder 51 may be used as a capacitor, and the capacitance between the electrode rod and the water level control cylinder 51, etc. due to changes in the water that contacts the electrode rod when electricity is applied may be measured, and the water level of the water that contacts the electrode rod in the water level control cylinder 51, etc. may be detected in an analog manner based on the measured capacitance.

[0042] The embodiments disclosed herein should be considered to be illustrative and not restrictive in all respects. The scope of the present invention is defined by the claims, not the above description, and is intended to include all modifications within the meaning and scope of the claims. [Explanation of symbols]

[0043] 1. Boiler 2 Boiler body 21 Top Header 22 Lower Header 23 Water pipe 3 Steam extraction pipe (steam extraction section) 31 Connecting pipe 4. Separator 41 Downpipe 5 Water level detector 51 Water level control cylinder 52 Electrode rod 52L L bar 52S S rod 6 Communication pipe 7. Water Supply Line

Claims

1. A boiler body for generating steam; A steam outlet that takes out the generated steam to the outside of the boiler body; a separator connected to the steam outlet and configured to separate the steam taken out by the steam outlet into steam and water; A water level detection unit that detects the water level of the boiler body, The water level detection unit has a communication pipe that communicates with the inside of the steam extraction unit.

2. The boiler according to claim 1 , wherein the steam outlet is disposed above the boiler body.

3. 2. The boiler according to claim 1, wherein the communication pipe communicates with the inside of the steam outlet at a position where a pressure loss after the generated steam is taken out of the boiler body falls within a predetermined range.

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