JP7413148B2 - Heater equipment for underground tanks - Google Patents

Description

The present invention relates to heater equipment for an underground tank that warms the ground in an annular area surrounding the side wall of an underground tank that stores low-temperature liquefied gas such as LNG or LPG.

As an example of this type of underground tank heater equipment, a side heater equipment disclosed in Patent Document 1 is known. This side heater equipment is a hot water circulation type heater equipment, and has a heater pipe that is buried in the ground around the underground tank and extends in the vertical direction. In this side heater equipment, a heating device, a circulation pump, an annular supply side header pipe, a supply side branch pipe, a heater pipe, a recovery side branch pipe, an annular recovery side header pipe, and a heater liquid are installed in the order of the heating device. It is designed to warm the ground around the underground tank by circulating (hot water).

Furthermore, in the side heater equipment described in Patent Document 1, a thermometer for measuring the temperature of the heater liquid is individually provided in each of the supply side branch pipe and the recovery side branch pipe, and these two thermometers The system is configured so that the amount of heat loss in the heater tube (that is, the amount of temperature drop in the heater liquid) can be monitored using data from the heater tube. As each thermometer, a type that measures local temperature, such as a thermocouple, was used.

Patent No. 6588831

However, in the side heater equipment described in Patent Document 1, in order to monitor the amount of temperature drop of the heater liquid in the heater pipe, it is necessary to separately provide a thermometer in each of the supply side branch pipe and the recovery side branch pipe. Therefore, in this side heater equipment, the wiring related to temperature measurement becomes complicated, and a new method is required.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide an underground tank heater facility that is capable of monitoring the amount of temperature drop of heater liquid in a heater pipe with a simple configuration.

According to one aspect of the present invention, there is provided a heater installation for an underground tank that warms the ground in an annular region surrounding a side wall of an underground tank that stores low-temperature liquefied gas. This underground tank heater equipment includes a heating device that warms a heater liquid for heat exchange with the ground, a heater pipe, a first branch pipe, a second branch pipe, and a first optical fiber through which light is incident. and a first temperature measuring section. The heater tube has an internal reciprocating flow path that reciprocates up and down in the annular region and allows the heater liquid to flow therethrough, and is embedded in the annular region. The first branch pipe has one end connected to the inlet end of the reciprocating flow path, and is for supplying the heater liquid warmed by the heating device to the heater pipe. The second branch pipe has one end connected to the outlet side end of the reciprocating flow path, and is for returning the heater liquid that has passed through the reciprocating flow path to the heating device. The first optical fiber is laid so as to pass through at least an outer surface of the first branch pipe and an outer surface of the second branch pipe. The first measurement unit measures the temperature distribution along the installation direction of the first optical fiber based on the return light from the first optical fiber.

According to the underground tank heater equipment according to the above aspect, the above-mentioned The temperature distribution along the installation direction of the first optical fiber is measured. In other words, it is possible to monitor the temperature drop of the heater liquid in the heater tube with a simple configuration that uses the first optical fiber as a temperature sensor and measures the temperature distribution along the installation direction of the first optical fiber. becomes.

BRIEF DESCRIPTION OF THE DRAWINGS It is a conceptual diagram for demonstrating the structure of the heater equipment for underground tanks which shows one Embodiment of this invention. It is a partial plan view containing the main part of the said heater equipment for underground tanks. It is a conceptual diagram for explaining the structure of the measuring device containing the 1st optical fiber of the said heater equipment for underground tanks. FIG. 3 is a diagram showing a state in which the first optical fiber is installed. FIG. 7 is a conceptual diagram for explaining a modification of the measuring device. 6 is a conceptual diagram for explaining the configuration of the measuring device shown in FIG. 5. FIG. FIG. 7 is a conceptual diagram for explaining another modification of the measuring device. It is a conceptual diagram for demonstrating yet another modification of the said measuring device. 9 is a side view of the heater tube in the measuring device shown in FIG. 8. FIG.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
FIG. 1 is a conceptual diagram for explaining the configuration of underground tank heater equipment 100 (hereinafter simply referred to as heater equipment 100) according to an embodiment of the present invention, and an underground tank 1 in which heater equipment 100 is used. It is also a cross-sectional view of the ground near . FIG. 2 is a plan view of essential parts of the heater equipment 100.

As shown in FIG. 1, the underground tank 1 is a tank for storing low-temperature liquefied gas such as LNG and LPG, and is buried underground. The underground tank 1 is constructed, for example, inside an underground continuous wall 2 made of reinforced concrete and constructed in a cylindrical shape in the ground. The underground tank 1 has a reinforced concrete frame consisting of a cylindrical side wall 3 and a bottom plate 4, and a spherical steel roof 5.

The heater equipment 100 is equipment for managing the frozen range of the ground in the annular area S surrounding the side wall 3 of the underground tank 1.

In this embodiment, the heater equipment 100 includes a heating device 10, a pump 20, a piping system 30 including a heater pipe 31, a measuring device 40, and a control unit 50. The heater equipment 100 circulates a heater liquid (for example, hot water of about 10 to 60°C) for heat exchange with the ground through the piping system 30, and exchanges heat between the heater liquid and the ground in the annular area S. It is configured to warm the ground in the annular region S. Note that as the heater liquid, in addition to hot water, an antifreeze solution such as brine may be used.

The heating device 10 is a facility for warming the heater liquid, and has a heating tank (not shown) that can store the heater liquid and warm the heater liquid using an appropriate type of heat source. The heating device 10 is provided midway through the piping system 30 on the ground.

The pump 20 is provided on the ground in a portion of the piping system 30 on the downstream side of the heating device 10, and pumps the heater liquid under pressure, and is of a variable flow rate type.

The piping system 30 constitutes a circulation flow path that circulates and distributes the heater liquid. The heater liquid warmed by the heating device 10 is returned to the heating device 10 again via the heater pipe 31 by the circulation flow path.

Specifically, the piping system 30 includes a heater pipe 31, a first branch pipe (hereinafter referred to as "supply side branch pipe") 32, and a second branch pipe (hereinafter referred to as "recovery side branch pipe") 33. , a supply side header pipe 34, a recovery side header pipe 35, a supply pipe 36, and a return pipe 37. The heater liquid warmed by the heating device 10 passes through the pump 20, supply pipe 36, supply side header pipe 34, supply side branch pipe 32, heater pipe 31, recovery side branch pipe 33, recovery side header pipe 35, return pipe 37, The water flows in this order and is returned to the heating device 10.

The heater tube 31 is a member that is embedded in the annular region S and is made of a steel piping member, and has a reciprocating flow path 31a that reciprocates up and down in the annular region S and circulates the heater liquid therein.

As shown in FIG. 2, the heater tubes 31 are installed at a plurality of locations in the annular region S at intervals in the circumferential direction. Although not particularly limited, the heater pipes 31 are provided, for example, at intervals of 3 m in the circumferential direction near the outer peripheral surface of the underground continuous wall 2, and a total of 80 heater pipes 31 are installed in the underground tank 1 (side wall). 3). In other words, a heater tube group 31A is constituted by a predetermined number (in this embodiment, the total number, that is, 80) of heater tubes 31 arranged in a row in the circumferential direction. Each heater pipe 31 extends vertically downward from the ground surface to approximately the depth of the bottom plate 4 of the underground tank 1, and has a length of, for example, about 50 to 65 m.

In this embodiment, the heater tube 31 has a so-called double tube type structure having an inner tube 311 and an outer tube 312, and is inserted into a hole previously formed in the ground by boring. Although not shown, the gap between the hole wall of the hole and the heater tube 31 is filled with a heat conductive filling material such as cement bentonite, which has a thermal conductivity higher than that of soil.

The inner pipe 311 has one end (downstream end in the flow direction) of the supply side branch pipe 32 connected to its upper part (in other words, the inlet end of the reciprocating flow path 31a), and has an open end at the lower part. . That is, as shown in FIG. 1, the heater liquid flows into the inner tube 311 from the upper part of the inner tube 311, flows downward in the inner tube 311, and flows out from the lower part of the inner tube 311.

The outer tube 312 surrounds the inner tube 311 and forms a flow path with an annular cross section therebetween. The lower part of the outer tube 312 has a closed end, and the recovery side branch pipe 33 is connected to the upper part (in other words, the outlet side end of the reciprocating flow path 31a). As shown in FIG. 1, there is a gap between the lower part of the outer tube 312 and the lower part of the inner tube 311, and the heater liquid flowing out from the lower part of the inner tube 311 is transferred between the inner tube 311 and the outer tube 312. The liquid flows upward through the flow path between them and is discharged from the upper part of the outer tube 312. In this embodiment, the reciprocating flow path 31a is constituted by a flow path within the inner tube 311, a gap between the lower part of the outer tube 312 and the lower portion of the inner tube 311, and the flow path having the annular cross section. .

The supply side branch pipe 32 has one end connected to the inlet side end (inflow side end) of the reciprocating flow path 31a, and is used for supplying the heater liquid warmed by the heating device 10 to the heater pipe 31. It is a piping member and is provided at each location where the heater pipe 31 is installed. The other end of each supply side branch pipe 32 is connected to a supply side header pipe 34, respectively.

The recovery side branch pipe 33 has one end connected to the outlet side end (discharge side end) of the reciprocating flow path 31a, and is a pipe for returning the heater liquid that has passed through the reciprocating flow path 31a to the heating device 10. It is a member and is provided at each location where the heater tube 31 is installed. The other end of each recovery side branch pipe 33 is connected to a recovery side header pipe 35, respectively.

The supply side header pipe 34 is a piping member into which the heater liquid from the heating device 10 flows, and to which the other end of each supply side branch pipe 32 is connected. The supply header pipe 34 is buried on the ground surface side in the annular region S, and is formed as a pipe closed in an annular shape so as to surround the heater pipe group 31A. The heater liquid that has flowed into the supply side header pipe 34 is distributed to each heater pipe 31 via the supply side branch pipe 32.

In the supply header pipe 34, each supply branch pipe 32 extends from the supply header pipe 34 toward the center of the underground tank 1 in the radial direction. Specifically, each supply side branch pipe 32 is provided so as to extend beyond the recovery side header pipe 35 and bridge (straddle) between the supply side header pipe 34 and the corresponding heater pipe 31.

The recovery side header pipe 35 is a piping member that extends parallel to the supply side header pipe 34 and is connected to the other end of the recovery side branch pipe 33. The recovery side header pipe 35 is also formed as a pipe closed in an annular shape so as to surround the heater pipe group 31A in the annular region S. In this embodiment, the recovery side header pipe 35 is arranged radially inside the supply side header pipe 34, that is, between the heater tube group 31A and the supply side header pipe 34.

In the recovery side header pipe 35, each recovery side branch pipe 33 extends from the recovery side header pipe 35 toward the center side of the underground tank 1 in the radial direction. Specifically, the recovery side branch pipe 33 extends in the vicinity of the supply header pipe 34 connected to the same heater pipe 31 and generally parallel to the supply header pipe 34 . As shown in FIG. 2, when the piping system 30 is viewed from above, the supply side branch pipes 32 and the recovery side branch pipes 33 are arranged alternately. Although not particularly limited, in this embodiment, on the ground surface side in the annular region S, the supply side branch pipe 32 and the recovery side branch pipe 33 are arranged at approximately the same depth (approximately the same height position in the vertical direction). be done.

The supply pipe 36 is a piping member that connects the heating device 10 and the supply side header pipe 34. A pump 20 is provided in the middle of the supply pipe 36.

The return pipe 37 is a piping member that connects the recovery side header pipe 35 and the heating device 10. The heater liquid returned into the recovery side header pipe 35 is returned (recovered) to the heating device 10 via the return pipe 37. The heater liquid returned to the heating device 10 is warmed again in the heating tank, and then supplied to each heater pipe 31 again via the pump 20, the supply header pipe 34, and the supply branch pipe 32.

Further, in this embodiment, a first gate valve 38 for flow rate adjustment is provided in the middle of each supply side branch pipe 32, and a second gate valve 39 for flow rate adjustment is provided in the middle of each recovery side branch pipe 33. ing. By adjusting each of the first gate valve 38 and the second gate valve 39, the circulating flow rate of the heater fluid in each heater pipe 31 is initially set to be approximately equal. Note that there are cases where an operator or the like repairs only an arbitrary heater pipe 31, but in such a case, the first gate valve 38 and the second gate valve 39 corresponding to the arbitrary heater pipe 31 should be closed. Then, the operator or the like can perform the above-mentioned repair work while continuing the circulating operation of the heater liquid by the heater equipment 100.

Here, the temperature of the heater liquid decreases as it flows through each heater pipe 31, but by being reheated by the heating device 10, the temperature of the heater liquid in the supply side header pipe 34 is maintained approximately constant. Ru. Specifically, the heater equipment 100 uses the control unit 50 to monitor the temperature of the heater liquid in the supply side header pipe 34 and the temperature of the heater liquid in the recovery side header pipe 35, and makes sure that the difference between these temperatures is within a predetermined range. The control unit 50 is configured to control the circulation flow rate of the pump 20 so that the temperature is below 2° C. (for example, below 2° C.). Through such circulation, the surface temperature of the heater tube 31 (outer tube 312) is maintained approximately constant over its entire length, and the heat of the heater liquid is removed from the surface of the heater tube 31 over the entire depth of the heater tube 31. is constructed so that it is conducted to the ground. Thereby, the position of the freezing line (that is, the boundary line between frozen ground and unfrozen ground) is controlled, and the frozen range of the ground in the annular region S around the underground tank 1 is controlled. Note that the temperature of the heater liquid in the supply side header pipe 34 and the temperature of the heater liquid in the recovery side header pipe 35 are monitored using, for example, a device different from the measuring device 40, and the measurement results by this device are sent to the control unit. 50. However, in this embodiment, as will be described later, the first optical fiber 41 as a temperature detection sensor in the measuring device 40 is partially laid along the recovery side header pipe 35. The temperature of the heater liquid in the pipe 35 may be monitored using the measurement results from the measuring device 40.

FIG. 3 is a conceptual diagram for explaining the configuration of the measuring device 40. The measuring device 40 is a device that can measure temperature using an optical fiber.

In this embodiment, the measuring device 40 includes a first optical fiber 41 as a temperature detection sensor, and a first temperature measuring section 42 for measuring (calculating) the temperature.

The first optical fiber 41 is a member that is laid so as to pass through at least the outer surface of the supply side branch pipe 32 and the outer surface of the recovery side branch pipe 33, and into which light is incident. As the first optical fiber 41, for example, a general-purpose coated optical fiber cable is used, which has a core serving as an optical path, a cladding covering the core, and a covering portion covering the cladding. Specifically, as the first optical fiber 41, a single-wire (that is, one optical path) coated type optical fiber cable made of a single coated wire is used. However, since optical fiber cables are inexpensive, the first optical fiber 41 may be a double-wire coated cable (that is, multiple optical paths) or a single-wire coated cable, which is made by covering the entire bundle of a plurality of single wires. A bundle of multiple cables may also be used. In this case, if for some reason it becomes impossible to perform measurements using the normally used channels (optical paths/lines), it is possible to switch to any of the remaining channels and perform measurements. Note that the installation route of the first optical fiber 41 and the like will be described later.

The first temperature measurement unit 42 can measure the temperature distribution along the installation direction of the first optical fiber 41 based on the return light (specifically, backscattered light) from the first optical fiber 41 (in other words, The temperature along the installation direction of the first optical fiber 41 can be continuously measured). The first temperature measuring section 42 is provided in a measurement chamber provided on the ground side, and is optically connected to the first optical fiber 41 via a measuring section side optical fiber 43 and a repeater 44. The measurement device 40 of this embodiment performs measurement using a so-called single-end method in which the light incident position (incidence end) is fixed to either one end 41a or the other end 41b of the first optical fiber 41. However, in the measuring device 40 of this embodiment, both one end 41a and the other end 41b of the first optical fiber 41 are connected to the repeater 44, and the light incident end is connected to one end of the first optical fiber 41 at a constant cycle. 41a and the other end 41b, so-called loop-type measurement (also referred to as double-end measurement or dual-end measurement) is configured.

Specifically, the first temperature measurement section 42 measures the temperature of the heater liquid at a plurality of locations spaced apart at intervals according to the processing capacity of the first temperature measurement section 42 in the installation direction of the first optical fiber 41. It is possible. Specifically, the first temperature measurement unit 42 measures the temperature of the portion that the first optical fiber 41 is in contact with (that is, the temperature of the outer surface of the piping system 30) as the temperature of the heater liquid. That is, the measuring device 40 indirectly measures the temperature of the heater liquid by measuring the temperature of the outer surface of the piping system 30. The temperature data at each location is associated with data indicating the measurement location. For example, the distance along the installation direction from the input end (one end 41a or the other end 41b) of the first optical fiber 41 is used as the data indicating the measurement location. Thereby, it is easily specified at which location in the installation direction of the first optical fiber 41 each temperature data is located.

Next, the installation route and installation state of the first optical fiber 41 will be explained with reference to FIGS. 2 to 4. FIG. 4 is a diagram showing a state in which the first optical fiber 41 is installed in the supply side branch pipe 32 or the collection side branch pipe 33. FIG. 4(A) is a side view of the supply side branch pipe 32 or the recovery side branch pipe 33 in which the first optical fiber 41 is installed, and FIG. 4(B) is a side view of the supply side branch pipe 32 or the recovery side branch pipe 33 at the position shown in the arrow AA shown in FIG. 4(A). FIG.

As shown by the thick line in FIG. 2, the first optical fiber 41 is laid so as to pass through at least the outer surface of the supply side branch pipe 32 and the outer surface of the recovery side branch pipe 33. In this embodiment, as shown in FIG. 2, the first optical fiber 41 extends so as to be folded back near the top of the heater tube 31 when viewed from above. Specifically, the folded portion 41c of the first optical fiber 41 that is folded back near the upper part of the heater tube 31 connects the portion of the first optical fiber 41 passing through the outer surface of the supply side branch tube 32 and the first optical fiber on the heater tube 31 side. 41 through the outer surface of the supply side branch pipe 32 are directly connected.

The heater tubes 31 are provided at a plurality of locations (80 locations in this embodiment), and the first optical fiber 41 is continuously extended for each heater tube group 31A consisting of a predetermined number of rows of heater tubes 31. There is. Note that the heater pipes 31 are arranged at equal intervals so as to surround the entire circumference (0° to 360°) of the underground tank 1. In FIG. 3, for clarity of illustration, the distance between adjacent heater tubes 31 is exaggerated and shown wider than it actually is.

In this embodiment, the heater tube group 31A is composed of all the heater tubes 31 (that is, 80 heater tubes 31) among the plurality of installed heater tubes 31, and is shown in FIGS. 2 and 3. As such, one first optical fiber 41 is extended so as to pass through the outer surface of the supply side branch pipe 32 and the outer surface of the recovery side branch pipe 33 corresponding to all the heater pipes 31 (that is, in one stroke). Specifically, the first optical fiber 41 has a header pipe-side laying part 41d that extends from the outer surface of the recovery-side header pipe 35 except for a range corresponding to each heater pipe 31 (specifically, an arc portion). are doing. One end 41a and the other end 41b of the first optical fiber 41 are both connected to the repeater 44, and the first optical fiber 41 extends generally in an annular shape as a whole.

Here, for each of the heater tubes 31 constituting the heater tube group 31A, numbers are given from the one end 41a side of the first optical fiber 41 to the other end 41b side (in counterclockwise order in FIGS. 2 and 3). In this embodiment, there are 80th heater tubes from the first heater tube 31. Regarding the supply side branch pipe 32 and the recovery side branch pipe 33, there are the 1st to 80th ones, respectively.The first supply side branch pipe 32, the first recovery side branch pipe 33, the second supply side branch pipe 32, The supply side branch pipes 32 and the recovery side branch pipes 33 are arranged alternately, such as the 80th supply side branch pipe 32, the 80th recovery side branch pipe 33, and so on. The first optical fiber 41 extends generally in an annular shape as a whole when seen in a plan view from above, and protrudes toward the heater tube 31 side at a portion corresponding to each heater tube 31. It reciprocates between the heater tube 31 in a zigzag pattern. That is, the first optical fiber 41 is connected from its one end 41a side to the outer surface of the recovery side header tube 35 near the repeater 44, the outer surface of the first supply side branch tube 32, the outer surface of the first recovery side branch tube 33, and the recovery side header tube 35 near the repeater 44. The part between the first heater pipe 31 and the second heater pipe 31 in the side header pipe 35, ... the outer surface of the 80th supply side branch pipe 32, the outer surface of the 80th recovery side branch pipe 33, the recovery side header The pipe 35 is extended in the order of the part between the 80th heater pipe 31 and the 1st heater pipe 31 in a single stroke, and the final other end 41b is connected to the repeater 44.

As shown in FIG. 4, the first optical fiber 41 is attached to the piping system 30 so as to be in close contact with the outer surface of the supply side branch pipe 32 and the outer surface of the recovery side branch pipe 33. Although not particularly limited, in FIG. 4, the first optical fiber 41 is inserted into a tubular heat shrink tube 45 together with the supply side branch pipe 32 and the recovery side branch pipe 33, and the heat shrink tube 45 is shrunk. By doing so, it is in close contact with the outer surface of the supply side branch pipe 32 and the outer surface of the recovery side branch pipe 33. Although not shown in the drawings, the header pipe-side installation portion 41d of the first optical fiber 41 is similarly attached to the outer surface of the recovery-side header pipe 35 using a heat shrink tube. However, the first optical fiber 41 is not limited to the heat-shrinkable tube 45, and can be attached to the supply side branch pipe 32, the recovery side branch pipe 33, or the recovery side header pipe 35 by directly bonding it or wrapping it with a band-shaped tape. It may be attached so as to be in close contact with the outer surface of the system 30 (32, 33, 35).

The control unit 50 centrally controls the operation of the entire equipment, and is configured to be able to drive the heating device 10, control the circulation flow rate of the pump 20 described above, and the like. As described above, the control unit 50 maintains a predetermined temperature difference between the temperature of the heater liquid in the supply side header pipe 34 and the temperature of the heater liquid in the recovery side header pipe 35 by controlling the circulating flow rate of the pump 20. It has a function to control the temperature so that it stays within a range of (for example, 2°C or less). However, this function does not individually monitor the amount of temperature drop of the heater liquid in each heater pipe 31. Regarding this point, in the present embodiment, the control unit 50 includes a determination unit 51 and a notification unit 52, and uses the measurement result from the first temperature measurement unit 42 to determine the amount of temperature drop of the heater liquid in each heater pipe 31. It has an individual monitoring function.

The determination unit 51 is based on first measurement data D1 corresponding to the supply side branch pipe 32 and second measurement data D2 corresponding to the recovery side branch pipe 33 among the measurement results by the measuring device 40 (first temperature measurement unit 42). The temperature T1 of the heater liquid in the supply side branch pipe 32 (specifically, the temperature of the outer surface of the supply side branch pipe 32) and the temperature T2 of the heater liquid in the recovery side branch pipe 33 (specifically, the temperature of the outer surface of the recovery side branch pipe 33). ) is configured to determine whether the temperature difference ΔT (=T1-T2) exceeds a predetermined threshold Tc (for example, 0.5° C.). Specifically, the threshold value Tc for the temperature difference ΔT (=T1-T2) is the upper limit for the temperature difference between the temperature of the heater liquid in the supply-side header pipe 34 and the temperature of the heater liquid in the recovery-side header pipe 35 described above. temperature (for example, 2°C).

Specifically, the determination unit 51 selects a data group corresponding to each supply side branch pipe 32 as the first measurement data D1 from among all the data indicating the temperature distribution along the installation direction of the first optical fiber 41. At the same time, the data group of the portion corresponding to each recovery side branch pipe 33 is specified as the second measurement data D2. Then, the determination unit 51 calculates the representative temperature (for example, average value) of each supply side branch pipe 32 as the temperature T1, based on the first measurement data D1. Similarly, the determination unit 51 calculates the representative temperature (for example, average value) of each collection side branch pipe 33 as the temperature T2, based on the second measurement data D2. Then, the determination unit 51 calculates the temperature difference ΔT (=T1−T2) between the temperature T1 and the temperature T2 for each of the supply side branch pipe 32 and the recovery side branch pipe 33 connected to the same heater pipe 31. It is determined whether any of the temperature differences ΔT exceeds the threshold Tc. In this way, the outer surface temperature of each of the pair of branch pipes (32, 33) connected to each heater pipe 31 is measured, and the difference between the outer surface temperature of one branch pipe and the outer surface temperature of the other branch pipe is calculated. By calculating the temperature difference ΔT between the temperature T1 and the temperature T2, the temperature difference ΔT (that is, the amount of temperature drop of the heater liquid in the heater tube 31) is individually monitored. The control unit 50 is configured to store the calculation result and determination result of the temperature difference ΔT in each heater tube 31 in association with the position of the heater tube 31.

When the determination unit 51 determines that the temperature difference ΔT (temperature drop amount) exceeds the threshold Tc in any one of the plurality of heater tubes 31, the notification unit 52 informs the operator of the position of the heater tube 31. It is a device for notifying people, etc., with letters and sounds, and includes, for example, a display section consisting of a display that displays judgment results, and an alarm that notifies abnormalities with sound. In addition, the operator etc. can ascertain the position of the heater tube 31 whose temperature drop exceeds the threshold Tc based on the notification result from the notification unit 52, and also understand the cause of the increase in the temperature drop in the heater tube 31. to be investigated individually in detail.

According to the heater equipment 100 according to this embodiment, the first The temperature distribution along the installation direction of the optical fiber 41 is measured. In other words, the amount of temperature drop of the heater liquid in the heater tube 31 can be monitored with a simple configuration in which the first optical fiber 41 is used as a temperature sensor and the temperature distribution along the installation direction of the first optical fiber 41 is measured. becomes possible. In this way, it is possible to provide the underground tank heater equipment 100 that can monitor the amount of temperature drop of the heater liquid in the heater pipe 31 with a simple configuration.

In this way, by individually monitoring the amount of temperature drop in each heater pipe 31, signs of trouble in the heater pipe 31 itself or trouble in the underground tank 1 can be grasped. Specifically, if there is a heater tube 31 where the reciprocating flow path 31a has begun to become clogged and the circulating flow rate has decreased, the sign of this will appear in the amount of temperature drop. In addition, a heat insulating material is generally provided inside the underground tank 1, and when this heat insulating material partially deteriorates, the amount of heat dissipated in the heater pipe 31 near the deteriorated part increases, and the sign of this is the amount of temperature drop. appears in

In this embodiment, the heater pipe 31 is installed at a plurality of locations spaced apart in the circumferential direction in the annular region S, and the supply side branch pipe 32 and the recovery side branch pipe 33 are provided at each installation location of the heater pipe 31, and the first The optical fiber 41 extends continuously for each heater tube group 31A formed by all the heater tubes 31 (that is, 80 heater tubes 31) among the plurality of installed heater tubes 31. Specifically, the outer surface temperature of a pair of branch pipes (32, 33) in each of the 80 heater tubes 31 is measured using a single first optical fiber 41, and the measurement results are used to determine the temperature of each of the heater tubes 31. The amount of temperature drop (temperature difference ΔT) of the heater liquid is calculated by calculation. That is, the temperature of the supply side branch pipe 32 and the recovery side branch pipe 33 (specifically, 160 locations) corresponding to all the heater pipes 31 in the piping system 30 is detected by one first optical fiber 41, and the temperature is Although there are multiple locations, the wiring in the measuring device 40 is simple. Thereby, the amount of temperature drop in each of the heater tubes 31 provided at a plurality of locations can be individually monitored with a simple configuration.

In the present embodiment, the first optical fiber 41 has a header pipe-side installation part 41d that extends from the outer surface of the recovery-side header pipe 35 excluding a range corresponding to the heater pipe 31 (specifically, an arc portion). ing. That is, the first optical fiber 41 is laid along the outer surface of the recovery side header pipe 35 as well. Thereby, the first optical fiber 41 can be easily and continuously laid (laid in a single stroke) using the constituent members of the piping system 30. Note that the first optical fiber 41 may be laid along the outer surface of the supply header pipe 34 instead of the outer surface of the recovery header pipe 35. Further, in this embodiment, the recovery side header pipe 35 is arranged radially inside the supply side header pipe 34, but the supply side header pipe 34 is arranged radially inside the recovery side header pipe 35. may be done.

FIG. 5 is a conceptual diagram for explaining a modification (modification 1) of the measuring device 40, and FIG. 6 is a conceptual diagram for explaining the configuration of the measuring device 40 shown in FIG. The measuring device 40 shown in FIGS. 5 and 6 is different from the measuring device 40 shown in FIGS. 1 to 4 only in the installation route and the number of first optical fibers 41. FIG. 5(A) is a partial plan view of the main part viewed from above, and FIG. 5(B) is a side view of the heater tube 31 viewed from the direction of arrow B shown in FIG. 5(A).

As shown in FIG. 5, the first optical fiber 41 may be laid so as to pass through the outer surface of the heater tube 31 in addition to the outer surface of the supply side branch pipe 32 and the recovery side branch pipe 33. Specifically, the first optical fiber 41 is a vertically reciprocating portion 41e that reciprocates up and down along the outer surface of the heater tube 31, and has a heater side end portion and a recovery side branch portion that pass through the outer surface of the supply side branch pipe 32. It has a vertical reciprocating section 41e that connects the heater side end of the section passing through the outer surface of the tube 33. That is, the portion of the first optical fiber 41 between the supply side branch pipe 32 and the collection side branch pipe 33 is laid so as to reciprocate up and down along the outer surface of the heater pipe 31. In this case, although not shown, the outer surface of the heater tube 31 in the first optical fiber 41 is surrounded by a heat shrink tube 45 as in FIG. There is. In addition, in the measurement device 40 according to this modification, the 80 installed heater tubes 31 are divided into 8 parts, and the heater tube group 31A is made up of 10 heater tubes 31 arranged in a row in the circumferential direction, and the first optical fiber 41 extends continuously for each heater tube group 31A consisting of ten heater tubes 31.

As shown in FIG. 6, in this modification 1, the measuring device 40 has eight first optical fibers 41 (eight series), and one end 41a and the other end of the first optical fiber 41 of each series. 41b are connected to repeaters 44 provided correspondingly. The measurement unit side optical fiber 43 is provided for each repeater 44, and each first optical fiber 41 is optically connected to the first temperature measurement unit 42 via the corresponding repeater 44 and measurement unit side optical fiber 43. It is connected. Further, the first temperature measurement unit 42 measures the temperature distribution along the installation direction of the first optical fibers 41 for each series based on the return light from each first optical fiber 41. Since the first optical fibers 41 of each series are laid so as to reciprocate up and down along the outer surface of the heater tube 31 in the portion on the heater tube 31 side, the first temperature measuring section 42 The temperature distribution of the heater liquid in the depth direction of each heater tube 31 can be measured based on the temperature distribution data from the portion corresponding to the outer surface of the tube 31. Therefore, for example, when the determination unit 51 determines that the temperature difference ΔT (amount of temperature drop) exceeds the threshold Tc in any one of the plurality of heater tubes 31, the measurement result of the temperature distribution in the depth direction Based on this, it is possible to specify at what depth in the heater tube 31 the trouble is occurring.

FIG. 7 is a conceptual diagram for explaining another modified example (modified example 2) of the measuring device 40. The temperature distribution in the depth direction was measured using the first optical fiber 41 and the first temperature measuring section 42 in the first modification, but in the second modification, the second optical fiber 41' and the second temperature measuring section 42' were used. It is configured to be performed individually using .

Specifically, in the second modification, the measuring device 40 further includes a second optical fiber 41' and a second temperature measuring section 42', in addition to the first optical fiber 41 and the first temperature measuring section 42. The second optical fiber 41' serves as a detection sensor that replaces the part of the first optical fiber 41 along the outer surface of the heater tube 31, and is laid so as to reciprocate up and down along the outer surface of the heater tube 31, and emits light. is incident. The second temperature measuring section 42' measures the temperature distribution along the installation direction of the second optical fiber 41' based on the return light from the second optical fiber 41'. Here, the second optical fiber 41' is provided for each heater tube 31, for example, and both ends thereof (one end 41'a and the other end 41'b) are exposed on the ground side and optically connected to the repeater 44'. It is configured to be detachable. For example, only one second temperature measuring section 42' is provided as a whole, and can be optically connected to the second optical fiber 41' via a measuring section side optical fiber 43' and a repeater 44'. It is configured. As a result, in the second modification, the temperature distribution of the heater liquid in the depth direction of the heater tube 31 can be measured for each heater tube 31 using the second optical fiber 41' and the second temperature measuring section 42'. . For example, when there is a heater tube 31 for which the determination unit 51 determines that the temperature difference ΔT (amount of temperature drop) exceeds the threshold Tc, the repeater 44' of the second optical fiber 41' corresponding to that heater tube 31 The second temperature measuring section 42' may be connected to the measuring section side optical fiber 43'. That is, in the measuring device 40, there is no need to provide a plurality of second temperature measuring sections 42'. Further, the data of the measurement results of the second temperature measurement section 42' can be outputted to the control section 50 of the measurement room, for example, wirelessly.

FIG. 8 is a conceptual diagram for explaining yet another modification (modification 3) of the measuring device 40, and FIG. 9 is a side view of the heater tube 31 in the measuring device 40 shown in FIG.

In the third modification, each heater tube 31 extends in a U-shape, and the reciprocating flow path 31a is constituted by the flow path within the heater tube 31 itself. The inlet side end and the outlet side end of the reciprocating flow path 31a in the U-shaped heater tube 31 are respectively located on the ground surface side, and each constitute a closed end. One end of the supply side branch pipe 32 is connected to the inlet side end of the reciprocating flow path 31a of the heater pipe 31, and one end of the recovery side branch pipe 33 is connected to the outlet side end of the reciprocating flow path 31a of the heater pipe 31. is connected. One U-shaped heater pipe 31 has a circulation flow rate equivalent to that of a double-pipe type heater pipe 31, and the heater pipe 31, supply side branch pipe 32, and recovery side branch pipe 33 have a circulation flow rate equivalent to that of the double pipe type heater pipe 31, and the heater pipe 31, supply side branch pipe 32, and recovery side branch pipe 33 are arranged in Figs. A thicker piping is used than in case 4. For example, 40 U-shaped heater tubes 31 are provided, which is half the number in the case of FIGS. 1 to 4. The distance between the portion forming the downward flow path and the portion forming the upward flow path in one heater tube 31 is adjusted, for example, to the distance between the double-pipe type heater tubes 31 that are adjacent to each other. It is being In the third modification using this U-shaped heater tube 31, the first optical fiber 41 is arranged upwardly, for example, as shown in FIGS. 8 and 9, similar to the first optical fiber 41 shown in FIG. When viewed from above, it extends in a generally annular shape as a whole and reciprocates in a zigzag pattern between the recovery side header pipe 35 and the heater pipe 31. Thereby, the measuring device 40 according to the third modification can also measure the amount of temperature drop of the heater liquid in each heater tube 31, similarly to the measuring device 40 according to the embodiment shown in FIGS. 1 to 4. Although not shown in the drawings, in the measuring device 40 according to the third modification, the first optical fiber 41 is connected to the outer surface of the supply side branch pipe 32 and the outer surface of the collection side branch pipe 33 as in the first modification, as well as to the heater pipe. It may be laid so as to pass through the outer surface of 31. Further, the measuring device 40 according to the third modification may include the second optical fiber 41' and the second temperature measuring section 42' of the second modification.

Although preferred embodiments and modifications thereof of the present invention have been described above, the present invention is not limited to the above embodiments and modifications thereof, and various modifications and changes can be made based on the technical idea of the present invention. It is possible.

DESCRIPTION OF SYMBOLS 1... Underground tank, 3... Side wall, 10... Warming device, 31... Heater pipe, 31a... Reciprocating flow path, 32... Supply side branch pipe (first branch pipe), 33... Recovery side branch pipe (second branch pipe), 34... Supply side header pipe, 35... Recovery side header pipe, 36... Supply pipe, 37... Return pipe, 41... First optical fiber, 41d... Header pipe side laying part, 41e... Vertical reciprocating part, 41'... Second Optical fiber, 42... First temperature measurement section, 42'... Second temperature measurement section, 51... Judgment section, 100... Heater equipment (heater equipment for underground tank), S... Annular area

Claims (4)

In underground tank heater equipment that warms the ground in an annular area surrounding the side wall of an underground tank that stores low-temperature liquefied gas,
a heating device that warms a heater liquid for heat exchange with the ground;
a heater tube embedded in the annular region and having therein a reciprocating flow path that reciprocates up and down in the annular region and circulates the heater liquid;
a first branch pipe having one end connected to an inlet side end of the reciprocating flow path and for supplying the heater liquid warmed by the heating device to the heater pipe;
a second branch pipe having one end connected to an outlet side end of the reciprocating flow path, and for returning the heater liquid that has passed through the reciprocating flow path to the heating device;
A first optical fiber that is laid so as to pass through at least the outer surface of the first branch pipe and the outer surface of the second branch pipe, into which light is incident, and extends so as to be folded in the vicinity of the heater pipe. , a first optical fiber;
a first temperature measurement unit that measures temperature distribution along the installation direction of the first optical fiber based on the return light from the first optical fiber;
a second optical fiber that is laid so as to reciprocate up and down along the outer surface of the heater tube, and into which light is incident;
a second temperature measurement unit that measures temperature distribution along the installation direction of the second optical fiber based on the return light from the second optical fiber;
Underground tank heater equipment, including : The heater tubes are installed at a plurality of locations spaced apart in the circumferential direction in the annular region,
The first branch pipe and the second branch pipe are provided at each installation location of the heater pipe,
2. The underground tank heater equipment according to claim 1 , wherein the first optical fiber extends continuously for each heater tube group consisting of a predetermined number of rows of heater tubes. an annular supply side header pipe into which the heater liquid from the heating device flows and to which the other end of the first branch pipe is connected;
an annular recovery side header pipe extending parallel to the supply side header pipe and connected to the other end of the second branch pipe;
a supply pipe connecting between the heating device and the supply side header pipe;
a return pipe connecting between the recovery side header pipe and the heating device;
further including;
2. The first optical fiber has a header tube-side installation portion that extends over a portion of the outer surface of the supply-side header tube or the outer surface of the recovery-side header tube excluding a range corresponding to the heater tube. Heater equipment for underground tanks as described in . The heater in the first branch pipe is based on the first measurement data corresponding to the first branch pipe and the second measurement data corresponding to the second branch pipe among the measurement results by the first temperature measurement unit. The underground according to any one of claims 1 to 3 , further comprising a determination unit that determines whether a temperature difference between the temperature of the liquid and the temperature of the heater liquid in the second branch pipe exceeds a predetermined threshold. Tank heater equipment.