Hot water tank and hot water tank modification method

Abstract

To provide a hot water tank that is easy to maintain. [Solution] The hot water storage tank (11) comprises a tank body (12) in which hot water is stored, a heat exchanger (13) that heats the hot water with steam via a heat transfer plate (13C), and a circulation pipe (14) having an outward pipe (14A) that guides the hot water from inside the tank body (12) to the heat exchanger, and a return pipe (14B) that guides the hot water from the heat exchanger (13) back into the tank body (12). Preferably, the hot water storage tank (11) comprises a pump (17) that sends hot water from the outward tank body (12) to the heat exchanger (13), and a make-up water pipe (20) that is connected to the outward pipe (14A) between the tank body (12) and the pump (17).

Description

[Technical Field]

[0001] This specification discloses a hot water tank and a method for retrofitting a hot water tank. [Background technology]

[0002] Japanese Utility Model Application Laid-Open Publication No. 56-144978 discloses a hot water storage tank in which a heat exchanger is arranged inside a pressure vessel. Figure 3 shows an example of a hot water storage tank 1 in which a heat exchanger 3 is similarly arranged inside a tank body 2. In this hot water storage tank 1, hot water is stored in the tank body 2. The heat exchanger 3 has a steam pipe 3A through which pressurized steam flows. This tank body 2 is watertight. Pressurized steam is passed through the steam pipe 3A inside the tank body 2. The hot water in the tank body 2 is heated by this pressurized steam. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Jikkai Showa 56-144978 Summary of the Invention [Problem to be solved by the invention]

[0004] A hot water storage tank like the one shown in Figure 3 has steam piping through which pressurized steam flows inside the tank body, and the tank body is considered a pressure vessel. This hot water storage tank is managed in accordance with legal regulations. For example, a central hot water supply system for a lodging facility requires a large tank body. This type of tank body is considered a Class 1 pressure vessel and must undergo regular inspections. In addition, handling this tank body requires a national license. Repairing this hot water storage tank requires government procedures, and modifications to this hot water storage tank are subject to restrictions.

[0005] The applicant's intention is to provide a hot water tank that is easy to maintain. [Means for solving the problem]

[0006] The hot water storage tank disclosed in this specification includes a tank body for storing hot water, a heat exchanger that heats the hot water with steam through a heat transfer plate; and, a circulation flow path having an outward flow path that guides the hot water from inside the tank body to the heat exchanger, and a return flow path that guides the hot water from the heat exchanger back into the tank body; Equipped with. [Effects of the Invention]

[0007] In this hot water tank, the tank body does not qualify as a pressure vessel. This hot water tank is easy to maintain. [Brief explanation of the drawings]

[0008] [Figure 1] FIG. 1 is a conceptual diagram of a hot water tank according to one embodiment. [Figure 2] FIG. 2 is a perspective view of a diffusion pipe provided in the hot water tank of FIG. [Figure 3] FIG. 3 is a conceptual diagram showing an example of a conventional hot water tank. DETAILED DESCRIPTION OF THE INVENTION

[0009] Hereinafter, preferred embodiments will be described in detail with reference to the drawings as appropriate.

[0010] Figure 1 shows a hot water tank 11. This hot water tank 11 is used, for example, in a central hot water supply system in a lodging facility. The hot water tank 11 includes a tank body 12 for storing hot water, a heat exchanger 13 for heating the hot water in the tank body 12, a circulation pipe 14 located between the tank body 12 and the heat exchanger 13, and a diffusion pipe 15 for discharging the hot water from the circulation pipe 14 into the tank body 12.

[0011] Furthermore, the hot water storage tank 11 is equipped with a temperature sensor 16 that detects the temperature of the hot water in the tank body 12. The hot water storage tank 11 is equipped with a pump 17 that circulates the hot water in the circulation piping 14. The hot water storage tank 11 is equipped with a steam piping 18 that supplies steam to the heat exchanger 13 and recovers steam and drain from the heat exchanger 13, and a switching valve 19 attached to the steam piping 18 and controls the supply and stop of steam. The hot water storage tank 11 is equipped with a make-up water piping 20 that is connected to the circulation piping 14 and can be replenished with water. The hot water storage tank 11 is equipped with a switching valve 21 attached to the make-up water piping 20 and controls the supply and stop of make-up water. The hot water storage tank 11 is equipped with a controller 22 that receives detection data from the temperature sensor 16 and controls the heat exchanger 13, the pump 17, and the switching valve 19.

[0012] The tank body 12 is watertight. The tank body 12 has a supply port 12A that sends the stored hot water to equipment within the facility, and a hot water supply pipe connection port 12B that connects to the tank body 12. The tank body 12 has a flange 12C with an opening to which the circulation pipe 14 is attached. The tank body 12 has a fusible plug 12D that releases high-pressure gas in the event of an abnormal rise in temperature or pressure. For example, in a central hot water supply system for a lodging facility, the tank body 12 has a large internal volume to supply hot water to the entire facility.

[0013] The heat exchanger 13 has a heated flow path 13A connected to the circulation pipe 14, a heating flow path 13B connected to the steam pipe 18, and heat transfer plates 13C that separate the heated flow path 13A from the heating flow path 13B. The heat exchanger 13 is, for example, a plate-type heat exchanger. The number of heat transfer plates 13C arranged in this heat exchanger 13 can be changed. The heating capacity of this heat exchanger 13 can be increased or decreased by changing the number of heat transfer plates 13C to change the number of heated flow paths 13A and heating flow paths 13B.

[0014] The circulation pipe 14 has an outward pipe 14A that guides hot water from the tank body 12 to the heated flow path 13A of the heat exchanger 13, and a return pipe 14B that guides hot water from the heated flow path 13A of the heat exchanger 13 to the tank body 12. The circulation pipe 14 has a flange 14C that serves as an attachment portion for attaching the circulation pipe 14 to the tank body 12. The circulation pipe 14 is attached to the flange 12C of the tank body 12 by the flange 14C. The circulation pipe 14 is fixed to the tank body 12 with the inlet of the outward pipe 14A and the outlet of the return pipe 14B positioned within the tank body 12.

[0015] The pump 17 is connected to the outward piping 14A. The make-up water piping 20 is connected to the outward piping 14A between the tank body 12 and the pump 17. The diffusion pipe 15 is connected to the outlet of the return piping 14B. The diffusion pipe 15 is located inside the tank body 12. The diffusion pipe 15 may be integrally molded with the return piping 14B.

[0016] FIG. 2 shows the diffusion pipe 15 together with a portion of the return pipe 14B. The diffusion pipe 15 has a hollow pipe shape with a closed end. The diffusion pipe 15 has a plurality of holes 15A whose positions and opening directions vary in the circumferential direction. The diffusion pipe 15 also has a plurality of holes 15A whose positions vary in the longitudinal direction. The plurality of holes 15A only need to have different positions and opening directions in the circumferential direction and different positions in the longitudinal direction, and the spacing and opening directions in the circumferential and longitudinal directions are not particularly limited.

[0017] The double-headed arrow Dm in Figure 2 represents the inner diameter of the diffusion pipe 15. The symbol Sm represents the diameter area of ​​the diffusion pipe 15. The double-headed arrow Da represents the inner diameter of the hole 15A. The symbol Sa represents the opening area of ​​the hole 15A. The total opening area of ​​the holes 15A is calculated by multiplying the opening area Sa by the number N of the holes 15A (N is a natural number greater than or equal to 2). In this diffusion pipe 15, the total opening area N·Sa is smaller than the diameter area Sm of the diffusion pipe 15. Furthermore, in this diffusion pipe 15, the total opening area N·Sa of the holes 15A is smaller than the diameter area of ​​the return pipe 14B.

[0018] The hot water storage tank 11 is equipped with a heat exchanger 13 that heats hot water with steam via a heat transfer plate 13C. The hot water storage tank 11 is equipped with a circulation pipe 14 having an outward pipe 14A that guides hot water from inside the tank body 12 to the heat exchanger 13, and a return pipe 14B that guides hot water from the heat exchanger 13 back into the tank body 12. In this hot water storage tank 11, the heat exchanger 13 is located outside the tank body 12. Even if the heat exchanger 13, through which pressurized steam flows, is damaged, the tank body 12 is not subjected to the steam pressure. This tank body 12 does not qualify as a pressure vessel. This tank body 12 is easy to maintain. Repairs to this tank body 12 do not require any government procedures.

[0019] The hot water storage tank 11 is equipped with a pump 17 that sends hot water from the tank body 12 to the heat exchanger 13 via an outward piping 14A, and a replenishment water piping 20 that is connected to the outward piping 14A between the tank body 12 and the pump 17. Even when hot water is sent out from the tank body 12, the replenishment water piping 20 prevents the tank body 12 from becoming negative pressure. This prevents the tank body 12 from being damaged by negative pressure.

[0020] The hot water storage tank 11 is equipped with a diffusion pipe 15 attached to the outlet of the return pipe 14B. The diffusion pipe 15 is located inside the tank body 12 and has a plurality of holes 15A on its outer periphery that open in different directions. The hot water in the tank body 12 is stirred by discharging hot water from the holes 15A of the diffusion pipe 15 into the tank body 12. The hot water storage tank 11 can make the temperature of the hot water in the tank body 12 uniform.

[0021] In this diffusion pipe 15, the total opening area N·Sa of the holes 15A is smaller than the diameter area Sm of the diffusion pipe 15. This allows the diffusion pipe 15 to reduce the difference in the amount of hot water released from the holes 15A far from the outlet of the return pipe 14B and the amount of hot water released from the holes 15A close to the outlet of the return pipe 14B. Therefore, in the diffusion pipe 15, it is preferable that the total opening area N·Sa is smaller than the diameter area Sm.

[0022] This hot water storage tank 11 can be obtained by modifying a storage tank in which the heat exchanger 3 using steam shown in Figure 3 is attached to the tank body 12. In this modification method, the circulation piping 14 is prepared. The heat exchanger 3 is removed from the flange 12C of the tank body 12. The inlet of the outward piping 14A and the outlet of the return piping 14B are positioned inside the tank body 12, and the circulation piping 14 is attached to the flange 12C of the tank body 12. This modification method allows the tank body 12, which corresponds to a pressure vessel, to be changed to a tank body 12 that does not correspond to a pressure vessel.

[0023] Repairs to the conventional hot water tank 1 in Figure 3 require government procedures because the tank body 2 is a Class 1 pressure vessel, and modifications to the hot water tank 1 are restricted. Repairs to the tank body 2 are time-consuming when it deteriorates over time. As mentioned above, by changing the tank body 12, which is a Class 1 pressure vessel, to a tank body 12 that is not a pressure vessel, the time and effort required for repairs and modifications can be reduced. This modification method shortens the construction period and reduces construction costs.

[0024] The internal volume is 0.04m 3 Therefore, in this modification method, the tank body 12 with an internal volume of 0.04 m3 or more is classified as a first-class pressure vessel by satisfying the specified requirements. 3 This is particularly effective for modifying the tank body 12 exceeding 1000 mm.

[0025] [Disclosure items] Each of the following sections discloses a preferred embodiment.

[0026] [Item 1] The tank itself holds hot water, a heat exchanger that heats the hot water with steam through a heat transfer plate; and, a circulation flow path having an outward flow path that guides the hot water from inside the tank body to the heat exchanger, and a return flow path that guides the hot water from the heat exchanger back into the tank body; A hot water storage tank.

[0027] [Item 2] Item 1. The hot water storage tank according to item 1, further comprising: a pump that sends hot water from the tank body to the heat exchanger through the forward flow path; and a makeup water flow path that is connected to the forward flow path between the tank body and the pump.

[0028] [Item 3] 3. The hot water storage tank according to claim 1, further comprising a diffusion tube attached to the outlet of the return flow path, located inside the tank body, and having a plurality of holes on its outer periphery that open in different directions.

[0029] [Item 4] A method for modifying a hot water tank, comprising: a tank body; and a steam heat exchanger having a steam pipe; wherein the steam pipe is positioned within the tank body and the steam heat exchanger is attached to the tank body, a circulation flow path having a forward flow path for guiding the hot water from the inside of the tank body to another heat exchanger, and a return flow path for guiding the hot water from the other heat exchanger to the inside of the tank body; Remove the steam heat exchanger from the tank body; A method for modifying a hot water storage tank, comprising: positioning an inlet of the forward flow path and an outlet of the return flow path within the tank body; and attaching the circulation flow path to the tank body. [Explanation of symbols]

[0030] 11. Hot water tank 12...tank body 12C···Flange (mounting part) 13...heat exchanger 13C...Heat transfer plate 14. Circulation piping (circulation flow path) 14A···Outward piping (outward flow path) 14B···Return piping (return flow path) 15. Diffusion tube 15A...hole 17 Pump 20...Makeup water piping (makeup water flow path)

Claims

[Claim 1] A method for modifying a hot water tank, comprising: a tank body; and a steam heat exchanger having a steam pipe; wherein the steam pipe is positioned within the tank body and the steam heat exchanger is attached to the tank body, another heat exchanger for heating the hot water in the tank body; another steam pipe for supplying steam to the other heat exchanger and recovering steam and drain from the other heat exchanger; and a circulation flow path having a forward flow path for guiding the hot water from inside the tank body to the other heat exchanger and a return flow path for guiding the hot water from the other heat exchanger into the tank body; Remove the steam heat exchanger from the tank body; The other heat exchanger and the other steam pipe are positioned outside the tank body; A method for modifying a hot water storage tank, comprising: positioning an inlet of the forward flow path and an outlet of the return flow path within the tank body; and attaching the circulation flow path to the tank body.

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