Electric boiler

Abstract

To provide an electric boiler having a structure appropriate to increase the output while securing the easiness of installation.SOLUTION: An electric boiler 1 includes a first lower header 2a extending in a X direction (a first direction) in a horizontal plane, a second lower header 2b arranged in parallel therewith in a Y direction (a second direction) perpendicular to the X direction (the first direction) in the horizontal plane, a plurality of water pipes 3 arranged in each of the first lower header 2a and the second lower header 2b while extending to the upper side, and one upper header 6 connected to each of the plurality of water pipes 3 via a riser tube 5.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The technology disclosed in this specification relates to an electric boiler. [Background technology]

[0002] Electric boilers that heat water with an electric heater are known. In Patent Document 1, three water tubes extending in the vertical direction are arranged between an upper header and a lower header, and an electric heater is installed in each water tube. The three water tubes are aligned along the length of the straight lower header. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2010-169356 A Summary of the Invention [Problem to be solved by the invention]

[0004] When increasing the output of an electric boiler, there are two methods: making the electric heater larger and increasing the number of water tubes. When making the electric heater larger, the water tubes and electric heater become longer, which reduces the workability of attaching and detaching the electric heater during maintenance. When increasing the number of water tubes, the upper header and lower header are extended to increase the number of water tubes, so the boiler body (a structure including the upper header, each water tube, and lower header) becomes elongated as a whole. This makes it difficult to secure an installation location because the installation area (footprint) of the boiler body becomes elongated, and there are problems in that the boiler body becomes shaped like an elongated fence, making it prone to falling over and unstable. There is a demand for an electric boiler with a structure suitable for increasing output while ensuring ease of installation.

[0005] The technique disclosed in this specification aims to provide an electric boiler having a structure suitable for increasing output while ensuring ease of installation. [Means for solving the problem]

[0006] This specification discloses an electric boiler comprising a first lower header extending in a first direction in a horizontal plane, a second lower header arranged side by side in a second direction perpendicular to the first direction in the horizontal plane, a plurality of water tubes arranged in each of the first lower header and the second lower header and extending upward, and an upper header connected to each of the plurality of water tubes via riser pipes. Effect of the Invention

[0007] According to the technology disclosed in this specification, an electric boiler having a structure suitable for increasing output while ensuring ease of installation is provided. [Brief description of the drawings]

[0008] [Figure 1] FIG. 1 is a perspective view that shows a schematic view of a boiler body of an electric boiler according to this embodiment. [Diagram 2] FIG. 2 is a side view that illustrates an example of the electric boiler according to the present embodiment. [Diagram 3] FIG. 3 is a top view that illustrates an example of the electric boiler according to the present embodiment. [Figure 4] FIG. 4 is a front view illustrating an example of the electric boiler according to the present embodiment. [Diagram 5] FIG. 5 is a front view showing a schematic diagram of a modified example of the can body. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] Hereinafter, an embodiment according to the present disclosure will be described with reference to the drawings, but the present disclosure is not limited to the embodiment. The components of the embodiments described below can be appropriately combined. In addition, some components may not be used.

[0010] In this embodiment, a three-dimensional orthogonal coordinate system is defined, and the positional relationship of each part will be described based on the three-dimensional orthogonal coordinate system. Two directions that are orthogonal to each other in a horizontal plane are defined as the X direction and the Y direction, respectively. One side of the X direction is defined as the X1 direction, and the other side of the X direction is defined as the X2 direction. The up-down direction (vertical direction) that is orthogonal to the X direction and the Y direction is defined as the Z direction.

[0011] <Electric boiler> Fig. 1 is a perspective view that typically shows a boiler body WS of an electric boiler 1 according to the present embodiment. Fig. 2 is a side view that typically shows an example of an electric boiler 1 according to the present embodiment. Fig. 2 shows a cross section of a portion of the electric boiler 1. Fig. 3 is a top view that typically shows an example of an electric boiler 1 according to the present embodiment. Fig. 4 is a front view that typically shows an example of an electric boiler 1 according to the present embodiment.

[0012] 1 and 2, the electric boiler 1 includes a first lower header 2a, a second lower header 2b, a plurality of water tubes 3 to which electric heaters 4 are attached, and an upper header 6 connected to each of the plurality of water tubes 3 via a riser pipe 5. As shown in Fig. 2, the electric boiler 1 includes a water supply device 20, a water level detector 30 that detects the water level in the water tubes 3, a control device 40 that controls the electric boiler 1, and a power source 41 that supplies power to the electric heater 4.

[0013] (Lower header) The boiler body WS shown in Fig. 1 is formed by interconnecting the first lower header 2a, the second lower header 2b, the water tubes 3, the riser tubes 5, and the upper header 6. The boiler body WS is a container for receiving a supply of water, evaporating it, and discharging steam. The electric boiler 1 is a once-through boiler. That is, an electric heater 4 is attached to each of the multiple water tubes 3, and all of the water tubes 3 are connected to the riser tube 5.

[0014] In the example of FIG. 1, the first lower header 2a and the second lower header 2b extend in the X direction (first direction) in a horizontal plane. The second lower header 2b is arranged side by side in the Y direction (second direction) perpendicular to the X direction (first direction) in the horizontal plane. The first lower header 2a and the second lower header 2b are made of cylindrical pipes with both ends sealed and extend linearly. The cylindrical portions of the first lower header 2a and the second lower header 2b have approximately the same dimensions.

[0015] The first lower header 2a and the second lower header 2b are containers that contain water supplied from a water supply device 20 (see FIG. 2). The first lower header 2a and the second lower header 2b are each provided with a plurality (six) of water pipes 3. The first lower header 2a and the second lower header 2b distribute the water supplied from the water supply device 20 to each of the plurality of water pipes 3. As shown in FIG. 1, the first lower header 2a and the second lower header 2b are connected to a drain pipe 7 and a downcomer pipe 8. The first lower header 2a and the second lower header 2b are each connected to one water supply pipe 9a, 9b.

[0016] (water pipe) A plurality of water tubes 3 are arranged in each of the first lower header 2a and the second lower header 2b and extend upward. In the first lower header 2a, six water tubes 3 are arranged at intervals in the X direction. In the second lower header 2b, six water tubes 3 are arranged at intervals in the X direction. As shown in FIG. 3, the interval (pitch Lp) between adjacent water tubes 3 is approximately equal in the first lower header 2a and the second lower header 2b. Each water tube 3 in the first lower header 2a and each water tube 3 in the second lower header 2b are shifted by half a pitch in the X direction.

[0017] The water pipe 3 distributes water from the first lower header 2a or the second lower header 2b. The water pipe 3 is a cylindrical pipe that distributes water and extends in a straight line. The water pipe 3 is arranged so that the central axis of the water pipe 3 is parallel to the Z axis. The lower end of the water pipe 3 communicates with the upper part of the first lower header 2a or the second lower header 2b.

[0018] (Electric heater) As shown in FIG. 2, the electric heater 4 is inserted into the interior of each of the water tubes 3 from the upper end of the tube. In this embodiment, a total of 12 electric heaters 4 are provided, one for each of the total of 12 water tubes 3. The electric heater 4 has a straight rod shape. The electric heater 4 is, for example, a sheath heater or a ceramic heater. The surface of the electric heater 4 faces the inner surface of the water tube 3 with a gap therebetween. The surface of the electric heater 4 comes into contact with the water supplied inside the water tube 3. When the surface of the electric heater 4 comes into contact with the water, the water is heated and steam is generated.

[0019] The electric heater 4 has a heat generating area FA that generates heat when current is applied, and a non-heat generating area NA. The non-heat generating area NA is disposed above the heat generating area FA. The heat generating area FA includes the lower end of the electric heater 4, and has a greater length in the Z direction than the non-heat generating area NA. The non-heat generating area NA includes the upper end of the electric heater 4. Temperature sensors (not shown) are provided in some or all of the twelve electric heaters 4. The temperature sensors measure the temperature of the upper part of the heat generating area FA, and output a signal according to the measurement value to the control device 40.

[0020] (Rising pipe and upper header) As shown in FIG. 1 , the riser pipe 5 connects the water pipes 3 and the upper header 6. The riser pipe 5 is a cylindrical pipe having a steam flow path. The riser pipe 5 circulates the steam generated in the water pipes 3. The lower end of the riser pipe 5 is connected to the upper part of the water pipes 3. The upper end of the riser pipe 5 is connected to the lower part of the upper header 6. The steam generated in the water pipes 3 is supplied to the upper header 6 via the riser pipe 5. One riser pipe 5 is provided for each of the multiple water pipes 3 (i.e., a total of 12 riser pipes 5). The upper ends of the multiple riser pipes 5 are each connected to one upper header 6.

[0021] The upper header 6 accommodates the steam supplied from the riser pipes 5. The upper header 6 is a cylindrical pipe sealed at both ends, and is a vessel for accommodating steam. In this embodiment, only one upper header 6 is provided, and it is connected to each of the multiple water pipes 3 via the riser pipes 5. The upper header 6 receives and collects the steam supplied from each of the multiple riser pipes 5.

[0022] As shown in Fig. 2, a steam pipe 11 is connected to the upper part of the upper header 6. A steam valve 12 is disposed on the steam pipe 11. When the steam valve 12 is opened, at least a part of the steam contained in the upper header 6 is discharged through the steam pipe 11.

[0023] The upper header 6 extends in a first direction (X direction) in a horizontal plane. As shown in Fig. 4, the upper header 6 is disposed at a position shifted in the Y direction with respect to each of the first lower header 2a and the second lower header 2b. In Fig. 4, the upper header 6 is disposed at a position shifted to one side in the Y direction (the left side in Fig. 4) with respect to the first lower header 2a and the second lower header 2b.

[0024] The riser pipes 5 are connected to the side of the upper part of the water pipes 3 in the Y direction. Each riser pipe 5 bypasses the upper areas of the water pipes 3 of the first lower header 2a and the second lower header 2b to connect to the upper header 6. In detail, the riser pipes 5 connected to each water pipe 3 of the first lower header 2a extend in the Y direction from the connection part, then bend upward in the Z direction to connect to the upper header 6. The riser pipes 5 connected to each water pipe 3 of the second lower header 2b pass between the water pipes 3 of the first lower header 2a in the Y direction, then bend upward in the Z direction to connect to the upper header 6.

[0025] Therefore, the upper header 6 and the uprising pipes 5 are not disposed in the upper region of each water pipe 3, and a maintenance work space is secured. This improves the workability when the electric heater 4 is pulled upward from the water pipe 3 for maintenance.

[0026] (water supply pipe) The water supply pipes 9a and 9b are connected to the first lower header 2a and the second lower header 2b, respectively. As shown in FIG. 2 (particularly illustrating the water supply pipe 9b), the water supply pipes 9a and 9b are connected to at least the first lower header 2a or the second lower header 2b at a middle position in the X direction (first direction). Here, the middle position is the middle position in the arrangement of the water pipes 3. Specifically, the water supply pipe 9b is connected to a position (middle position) where the six water pipes 3 of the second lower header 2b are divided into three pipes each. Similarly, the water supply pipe 9a is connected to a position (middle position) where the six water pipes 3 of the first lower header 2a are divided into three pipes each. Three water pipes 3 are arranged on each of one end side (X1 side) and the other end side (X2 side) in the X direction with respect to the connection position of the water supply pipe 9a. In addition, when the number of water pipes 3 in the first lower header 2a or the second lower header 2b is an odd number (2N+1), the intermediate position is the position where the water pipes 3 are divided into N and N+1 at one end and the other end.

[0027] The water supply pipes 9a, 9b have water supply ports SP1, SP2 facing one end side and the other end side in the X direction (first direction) at least inside the first lower header 2a or the second lower header 2b in the X direction (first direction). Specifically, a T-shaped pipe joint 9c is arranged inside the second lower header 2b, and the ends of the water supply pipes 9a, 9b are connected to the inlets of the pipe joint. Two openings of the pipe joint 9c branched into a T shape are directed to one end side (X1 side) and the other end side (X2 side) in the X direction, respectively constituting a pair of water supply ports SP1, SP2. As a result, the water supply port SP1 supplies water toward the three water pipes 3 on one end side, and the water supply port SP2 supplies water toward the three water pipes 3 on the other end side. Although only the water supply ports SP1, SP2 of the water supply pipe 9b are illustrated in FIG. 2, the same applies to the water supply pipe 9a.

[0028] The water supply pipes 9a, 9b are connected to a water supply device 20. The water supply device 20 has a water supply branch 21 connected to the water supply pipes 9a, 9b, a water supply pump 22, and a water supply valve 23 provided between the water supply branch 21 and the water supply pump 22.

[0029] The water supply pump 22 discharges water to the first lower header 2a and the second lower header 2b via the water supply valve 23, the water supply branch 21, and each of the water supply pipes 9a, 9b. This supplies water to each of the water pipes 3. The water supply device 20 can adjust the amount of water supply per unit time by the control device 40 controlling the rotation speed of the water supply pump 22. The water supply valve 23 opens and closes the water supply path to the water supply branch 21. When the water supply valve 23 functions as a flow rate adjustment valve, the water supply valve 23 may adjust the amount of water supply per unit time.

[0030] (drain pipe) 1 and 4, the drain pipe 7 is connected to the lower part of each of the first lower header 2a and the second lower header 2b. The drain pipe 7 is connected to one end of the first lower header 2a and the second lower header 2b in the X direction (on the X1 side of each water pipe 3) (see FIG. 2).

[0031] The drain pipe 7 has a communication portion 7a that communicates the first lower header 2a and the second lower header 2b. The drain pipe 7 has pipe portions 7b and 7c that extend downward from the first lower header 2a and the second lower header 2b, respectively, and are bent so as to approach each other in the Y direction, and the pipe portions 7b and 7c are each connected to the communication portion 7a. The communication portion 7a is a T-shaped pipe joint. The communication portion 7a is disposed between the first lower header 2a and the second lower header 2b in the Y direction. The drain pipe 7 has a pipe portion 7d (see FIG. 1) that extends from the communication portion 7a and discharges the joined water. A drain valve 13 (see FIG. 2) is disposed in the pipe portion 7d. When the drain valve 13 opens, at least a portion of the water contained in the first lower header 2a and the second lower header 2b is discharged (called blow) through the drain pipe 7.

[0032] In this embodiment, two separate steam generation systems are provided: a system of six water tubes 3 arranged in the first lower header 2a, and a system of six water tubes 3 arranged in the second lower header 2b. The communication unit 7a communicates the two systems with each other, thereby achieving the function of aligning the water levels of the water tubes 3 even if there is variation in the amount of steam generated or the amount of water distributed between the systems.

[0033] 4, the pipe section 7b from the first lower header 2a to the communicating section 7a and the pipe section 7c from the second lower header 2b to the communicating section 7a are symmetrical in the Y direction with the communicating section 7a at the center. Therefore, the flow resistances from the first lower header 2a and the second lower header 2b to the communicating section 7a are equivalent, improving the uniformity of the discharge amount during blowing.

[0034] (Downpipe) The downcomer pipe 8 is connected to the upper header 6 and branches at a branching portion 8a to connect to each of the first lower header 2a and the second lower header 2b. The steam flowing into the upper header 6 is wet saturated steam containing air and water, and the downcomer pipe 8 returns the water that has flowed into the upper header 6 to the first lower header 2a and the second lower header 2b. In the electric boiler 1 according to this embodiment, a separator (gas-liquid separator, not shown) is not provided, so the downcomer pipe 8 is directly connected to the upper header 6, but a separator may be provided between the upper header 6 and the downcomer pipe 8, and the downcomer pipe 8 may be connected to the separator.

[0035] As shown in FIG. 1, the downcomer pipe 8 connects one end of the upper header 6 in the X direction (X1 side of each uprising pipe 5) to one end of the first lower header 2a and the second lower header 2b in the X direction (X1 side of each water pipe 3). As shown in FIG. 4, the downcomer pipe 8 is composed of a branching section 8a and pipe sections 8b to 8d, and the upper end of the pipe section 8b is connected to the lower part of the upper header 6. The pipe section 8b extends downward in the Z direction from the upper header 6, and then bends to connect to the branching section 8a. The branching section 8a is disposed between the first lower header 2a and the second lower header 2b. The branching section 8a is a T-shaped pipe joint, and branches the downcomer pipe 8 into two in the Y direction toward the first lower header 2a side and the second lower header 2b side. The pipe section 8c is bent downward from the branching section 8a to connect to the upper part of the first lower header 2a. The pipe section 8d is bent downward from the branch section 8a and connected to the upper part of the second lower header 2b. With this configuration, the branch section 8a, like the drain pipe 7, has the function of connecting the insides of the first lower header 2a and the second lower header 2b to each other.

[0036] The pipe section 8c from the branching section 8a to the first lower header 2a and the pipe section 8d from the branching section 8a to the second lower header 2b are shaped symmetrically in the Y direction with respect to the branching section 8a as the center. Therefore, the flow resistances from the branching section 8a to the first lower header 2a and the second lower header 2b are equal, improving the uniformity of the distribution amount of water from the downcomer pipe 8.

[0037] The downcomer pipe 8 has a concentrated drain outlet 14 between the upper header 6 and the branch 8a. The concentrated drain outlet 14 is connected to a concentrated drain valve 15 (see FIG. 2). By opening the concentrated drain valve 15, the water in the downcomer pipe 8 can be discharged to the outside (called concentrated blow). The impurity concentration in the boiler body WS is reduced by the water supply from the water supply pipes 9a and 9b and the water discharged from the concentrated drain outlet 14.

[0038] The downcomer pipe 8 has a water quality measuring unit 16 (see FIG. 2) between the branch 8a and the concentrated drain outlet 14. The water quality measuring unit 16 is connected to a connection port 8e (see FIG. 1) provided between the branch 8a and the concentrated drain outlet 14. The water quality measuring unit 16 has, for example, an electrical conductivity sensor that measures the electrical conductivity of the water in the pipe. By monitoring the electrical conductivity of the water in the boiler body WS with the water quality measuring unit 16, it is possible to grasp the degree of concentration of the water in the boiler body WS. Then, when the water in the boiler body WS becomes more concentrated than a predetermined amount as the electric boiler 1 is operated, the concentrated drain valve 15 is opened to perform concentrated blow.

[0039] The connection positions of the downcomer pipe 8 to the first lower header 2a and the second lower header 2b and the connection positions of the drain pipe 7 to the first lower header 2a and the second lower header 2b are approximately aligned in the X direction (see FIG. 2) and face each other in the Z direction (see FIG. 4). Since the downcomer pipe 8 is connected directly above the drain pipe 7, precipitates contained in the water returned from the downcomer pipe 8 tend to accumulate near the drain pipe 7. Therefore, the deposits (sludge) in the boiler body WS can be effectively removed during drainage (blowing) through the drain pipe 7.

[0040] (Water Level Detector) As shown in FIG. 2, the water level detector 30 is connected to the upper header 6 and at least one of the first lower header 2a or the second lower header 2b via a detector connection pipe 31. In this embodiment, the water level detector 30 is connected only to the first lower header 2a (see FIG. 3), but it may be connected only to the second lower header 2b or to both. The detector connection pipe 31 includes an upper communication pipe 31a that connects the upper end of the water level detector 30 to the upper header 6, and a lower communication pipe 31b that connects the lower end of the water level detector 30 to the first lower header 2a. Note that the water level detector 30 and the detector connection pipe 31 are not shown in FIG. 1 and FIG. 4.

[0041] The upper communicating pipe 31a is disposed at one end (X1 side) of the upper header 6 in the X direction (first direction). The lower communicating pipe 31b is disposed at one end of the first lower header 2a in the X direction. Therefore, in this embodiment, the detector connecting pipe 31, the downcomer pipe 8, and the drain pipe 7 are all disposed at one end of the first lower header 2a (or the second lower header 2b) in the X direction (first direction). The detector connecting pipe 31, the downcomer pipe 8, and the drain pipe 7 are disposed at one end (X1 side) of the X direction relative to the multiple (12) water pipes 3.

[0042] The water level detector 30 has a detection container 32 and a plurality of electrode rods 33 arranged in the detection container 32. The upper and lower surfaces of the detection container 32 are connected to the upper communicating pipe 31a and the lower communicating pipe 31b, respectively, and water is contained therein. The water level of the detection container 32 and the water level of each water tube 3 are substantially equal. The water level detector 30 can detect the water level of the water tube 3 by detecting the water level of the detection container 32. The water level refers to the position of the water surface in the Z-axis direction.

[0043] The plurality of electrode rods 33 are disposed inside the detection container 32. In this embodiment, the electrode rods 33 include three electrode rods 33A, 33B, and 33C. Note that two or four or more electrode rods 33 may be provided.

[0044] The electrode rod 33 is a rod-shaped member made of a conductive material. The upper end of the electrode rod 33 is held by the upper lid of the detection container 32 via an insulating member (not shown). The lower end of the electrode rod 33 is separated from the inner surface of the detection container 32.

[0045] The positions of the lower ends of the electrode bars 33A, 33B, and 33C in the Z-axis direction are different. In this embodiment, among the electrode bars 33A, 33B, and 33C, the lower end of the electrode bar 33A is located at the highest position, the lower end of the electrode bar 33B is located at the next highest position after the lower end of the electrode bar 33A, and the lower end of the electrode bar 33C is located at the lowest position.

[0046] The detection container 32 is made of a conductive material. The detection container 32 functions as a common electrode for the multiple electrode rods 33. When the water contained in the detection container 32 comes into contact with the lower ends of the electrode rods 33, electricity is conducted between the detection container 32 and the electrode rods 33 via the water.

[0047] The water level detector 30 detects the water level in the detection container 32 based on the presence or absence of a current flowing through each of the multiple electrode rods 33. In the Z-axis direction, the position of the lower end of the electrode rod 33C and the position of the upper end (boundary EG) of the heat generating area FA of the electric heater 4 are substantially the same.

[0048] When the electrodes 33B and 33C detect water but the electrode 33A does not detect water, the control device 40 operates the water supply pump 22 to supply water. When all of the electrodes 33A, 33B, and 33C detect water, the control device 40 stops the operation of the water supply pump 22 to stop water supply. This maintains the water level in the water tube 3 at a position between the lower end of the electrode 33A and the lower end of the electrode 33B. By maintaining the water level in the water tube 3 between the lower end of the electrode 33A and the lower end of the electrode 33B, the entire heat generating area FA of the electric heater 4 can be immersed in water. The control device 40 may stop the power supply to the electric heater 4 when the electrode 33C does not detect water for a predetermined time.

[0049] <Installation area (footprint) of the can body> As shown in FIG. 3, the first lower header 2a and the second lower header 2b have a length Lx in the X direction. The length Lx corresponds to a length for arranging six water pipes 3 at a pitch Lp and for securing an area for connecting a downcomer pipe 8 and a discharge pipe 7 to one end (X1 side). The first lower header 2a has one end extended to connect a detector connection pipe 31 of a water level detector 30 to the extended part (see FIG. 2), but the extended part will be omitted in the description here. The first lower header 2a and the second lower header 2b are arranged in the Y direction, separated by a length Ly. The first lower header 2a and the second lower header 2b have a diameter d. The approximate shape of the installation area (footprint) of the boiler body WS is a rectangle of (X direction x Y direction) = "Lx x (Ly + 2d)".

[0050] <Effects> As described above, the electric boiler 1 of this embodiment includes the first lower header 2a extending in the X direction (first direction) in a horizontal plane, the second lower header 2b arranged in a row in the Y direction (second direction) perpendicular to the X direction (first direction) in the horizontal plane, the water tubes 3 arranged in multiples in each of the first lower header 2a and the second lower header 2b and extending upward, and one upper header 6 connected to each of the multiple water tubes 3 via a riser pipe 5. By arranging the first lower header 2a and the second lower header 2b in parallel and providing multiple water tubes 3, the number of water tubes 3 can be increased, and the output of the electric boiler 1 can be increased. If all 12 water tubes 3 are arranged in one lower header, the length dimension in the X direction of the boiler body WS in FIG. 3 becomes double (2×Lx) by simple calculation, and the width in the Y direction becomes less than half (d). In this case, the installation area (footprint) of the boiler body has a very large length dimension in the X direction, making it difficult to secure an installation space, and a small width dimension in the Y direction makes the boiler body WS prone to tipping over and unstable. In contrast, in this embodiment, the length (Lx) in the X direction of the first lower header 2a and the second lower header 2b can be reduced, making it unnecessary to secure a long and narrow installation space. In addition, the width dimension (Ly+2d) in the Y direction of the installation area of ​​the boiler body WS is not excessively small relative to the length (Lx) in the X direction, improving stability. Therefore, according to this embodiment, an electric boiler 1 having a structure suitable for increasing output while ensuring ease of installation is obtained.

[0051] In this embodiment, the electric boiler 1 further includes a drain pipe 7 having a communication portion 7a that connects the first lower header 2a and the second lower header 2b. This allows the blow drain pipe 7 to function as a connecting pipe, so there is no need to provide a structure (connecting pipe) for connecting the first lower header 2a and the second lower header 2b. As a result, the structure of the boiler body WS can be simplified.

[0052] In this embodiment, the electric boiler 1 further includes a downcomer pipe 8 that is connected to the upper header 6 and branches at a branching portion 8a to connect to each of the first lower header 2a and the second lower header 2b. This allows the downcomer pipe 8 to function as a connecting pipe, so there is no need to provide a structure (connecting pipe) for connecting the first lower header 2a and the second lower header 2b. In addition, water with an increased impurity concentration can be branched at the branching portion 8a and distributed to the first lower header 2a and the second lower header 2b, so that the variation (bias) in the impurity concentration of the water between the first lower header 2a and the second lower header 2b can be suppressed. As a result, the variation in the boiling state, water level, and progress of scale adhesion in each water tube 3 can be suppressed. The same effect can be obtained even when a separator is provided between the downcomer pipe 8 and the upper header 6.

[0053] In this embodiment, the electric boiler 1 further includes feedwater pipes 9a, 9b connected to the first lower header 2a and the second lower header 2b, respectively, and the feedwater pipes 9a, 9b are connected to at least the intermediate positions in the X direction (first direction) of the first lower header 2a or the second lower header 2b. Here, a gradient occurs in the water temperature, etc., depending on the distance from the connection positions of the feedwater pipes 9a, 9b. Therefore, by connecting the feedwater pipes 9a, 9b to the intermediate positions in the X direction, the gradient between one end side (X1 side) and the other end side (X2 side) inside the first lower header 2a and the second lower header 2b can be made closer, and the variation in the water temperature, etc. can be suppressed.

[0054] In this embodiment, the water supply pipes 9a, 9b have water supply ports SP1, SP2 facing one end side and the other end side in the X direction (first direction) at least inside the first lower header 2a or the second lower header 2b in the X direction (first direction). Because water can be pumped from the center toward each end inside the first lower header 2a and the second lower header 2b, the formation of gradients in the water temperature, impurity concentration, etc. can be effectively suppressed.

[0055] In this embodiment, the electric boiler 1 further includes a water level detector 30 connected to the upper header 6 and at least one of the first lower header 2a and the second lower header 2b via a detector connection pipe 31, and the detector connection pipe 31, the downcomer pipe 8, and the drain pipe 7 are all disposed at one end side of the first lower header 2a or the second lower header 2b in the X direction (first direction). This allows the group of pipes in which the water level detector 30 and valves (drain valve 13, concentrated drain valve 15) are disposed to be concentrated and disposed at the end of the boiler body WS. As a result, an operator can perform daily inspection and maintenance in one place, improving workability.

[0056] In this embodiment, the downcomer pipe 8 has a concentrated drain outlet 14 between the upper header 6 and the branch 8a. Here, when the concentrated drain outlet 14 is provided downstream of the branch 8a (either the pipe 8c or the pipe 8d), the impurity concentration is reduced in one of the first lower header 2a and the second lower header 2b by concentrated blow from the concentrated drain outlet 14, but the impurity concentration is difficult to reduce in the other, so that a bias in the impurity concentration is likely to occur between the first lower header 2a and the second lower header 2b. Therefore, by providing the concentrated drain outlet 14 between the upper header 6 and the branch 8a, the bias in the impurity concentration between the first lower header 2a and the second lower header 2b can be suppressed.

[0057] In this embodiment, the downcomer pipe 8 further includes a water quality measuring unit 16 between the branching portion 8a and the concentrated drain outlet 14. If the water quality measuring unit 16 is provided downstream of the branching portion 8a (either the pipe portion 8c or the pipe portion 8d), the water quality of either the first lower header 2a or the second lower header 2b is measured, which makes it difficult to grasp the change in water quality when the distribution of water from the downcomer pipe 8 is biased. Therefore, by providing the water quality measuring unit 16 between the upper header 6 and the branching portion 8a, the water quality before distribution to the first lower header 2a and the second lower header 2b can be measured, and the water quality in the boiler body WS can be grasped more accurately even if the distribution of water is biased.

[0058] <Modification> In the embodiment, the upper header 6 (see FIG. 4) is disposed at a position shifted to one side in the Y direction from the first lower header 2a and the second lower header 2b, but the upper header 6 may be disposed as shown in FIG. 5, for example. FIG. 5 is a front view showing a modified example of the can body WS. In FIG. 5, the upper header 6 is disposed at a position between the first lower header 2a and the second lower header 2b in the Y direction. Compared to the configuration in FIG. 4, the distance between the first lower header 2a and the second lower header 2b (Ly in FIG. 3) is larger, but since the upper header 6 does not protrude in the Y direction, the Y direction dimension of the entire can body WS can be reduced. In addition, since the center of gravity of the entire can body WS can be moved closer to the center in the Y direction, stability is improved even if the Y direction dimension of the entire can body WS is reduced.

[0059] Also, in the embodiment, an example is shown in which the first lower header 2a and the second lower header 2b are provided, but three or more lower headers may be provided, i.e., a third lower header, a fourth lower header, .... Also, the number of water pipes 3 provided in each lower header is not particularly limited, and may be any number as long as it is more than one.

[0060] In addition, in the embodiment, an example in which the drain pipe 7 is provided with the communication portion 7a has been shown, but the drain pipe 7 may not be provided with the communication portion 7a, and the drain pipe 7 may be provided individually at each lower header. Similarly, an example in which the downcomer pipe 8 is provided with the branch portion 8a has been shown, but the downcomer pipe 8 may not be provided with the branch portion 8a, and the downcomer pipe 8 may be provided individually at each lower header. In these cases, a communication pipe that communicates each lower header may be provided separately from the drain pipe 7 and the downcomer pipe 8.

[0061] In the embodiment, the water supply pipe 9a and the water supply pipe 9b are connected to the middle positions in the X direction of the first lower header 2a and the second lower header 2b, respectively, but they may be connected to the ends in the X direction, or may be connected to multiple positions (for example, one end and the other end in the X direction). Also, a water supply pipe may be provided to only one of the first lower header 2a and the second lower header 2b, and the first lower header 2a and the second lower header 2b may be connected to each other, thereby supplying water to both lower headers through one water supply pipe. Also, the water supply pipes 9a and 9b may have one water supply port.

[0062] In addition, in the embodiment, an example is shown in which the detector connection pipe 31, the downflow pipe 8, and the drain pipe 7 are arranged at the ends in the X direction, but the pipes may be concentrated in the center in the X direction or may be distributed and arranged in separate positions. [Explanation of symbols]

[0063] 1...electric boiler, 2a...first lower header, 2b...second lower header, 3...water pipe, 4...electric heater, 5...rising pipe, 6...upper header, 7...drain pipe, 7a...connecting section, 7b, 7c, 7d...pipe section, 8...downcomer pipe, 8a...branching section, 8b, 8c, 8d...pipe section, 8e...connection port, 9a, 9b...feed pipe, 9c...pipe joint, 11...steam pipe, 12...steam valve, 13...drain valve, 14...concentrated drain port, 15...concentrated drain valve, 16...water quality measuring section, 20...water supply device, 21...water supply branch section, 22...water supply pump, 23...water supply valve, 30...water level detector, 31...detector connecting pipe, 31a...upper connecting pipe, 31b...lower connecting pipe, 32...detection container, 33 (33A, 33B, 33C)...electrode rod, 40...control device, 41...power source, FA...heat generating area, NA...non-heat generating area, EG...boundary, SP1, SP2...water supply port, WS...boiler body, Lp...pitch.

Claims

1. a first lower header extending in a first direction in a horizontal plane; second lower headers arranged side by side in a second direction perpendicular to the first direction in the horizontal plane; a plurality of water pipes are disposed in each of the first lower header and the second lower header and extend upward; an upper header connected to each of the plurality of water pipes via a riser pipe; Electric boiler.

2. a drain pipe having a communication portion that communicates the first lower header and the second lower header, 2. The electric boiler of claim 1.

3. a downcomer connected to the upper header or to the separator, branching at a branching portion to connect to each of the first lower header and the second lower header, 2. The electric boiler of claim 1.

4. a water supply pipe connected to each of the first lower header and the second lower header, The water supply pipe is connected to at least the first lower header or the second lower header at a middle position in the first direction. An electric boiler according to any one of claims 1 to 3.

5. the water supply pipe has a water supply port facing one end side and the other end side in the first direction at least inside the first lower header or the second lower header in the first direction; 5. An electric boiler as claimed in claim 4.

6. a water level detector connected to the upper header and at least one of the first lower header and the second lower header via a detector connection pipe; the detector connection pipe, the downcomer pipe, and the drain pipe are all disposed on one end side of the first lower header or the second lower header in the first direction; 4. An electric boiler as claimed in claim 3.

7. The downcomer has a concentrated outlet between the upper header and the branch.

4. An electric boiler as claimed in claim 3.

8. The downcomer further has a water quality measuring unit between the branching portion and the concentrated drain outlet.

8. An electric boiler as claimed in claim 7.

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