A domestic water purification device

Abstract

The invention relates to a domestic water purification device, which adopts a purifier to remove impurities, harmful ions and bacteria in domestic water, adopts tube-in-tube technology to realize the purification treatment of domestic water, adopts hot air generated by a solar hot air heater to heat water supply, eliminates the defects of traditional direct-insertion vacuum collector tube water heaters, has strong versatility, can effectively improve the water supply quality of domestic water, has flexible and convenient operation and adjustment, and helps to improve people's quality of life.

Description

Technical Field

[0001] The invention relates to the technical field of domestic water, and in particular to a domestic water purification device adopting a purified water circulation technology. Background Art

[0002] As people's living standards improve, their requirements for quality of life are getting higher and higher, such as water quality.

[0003] The pipes for ordinary household water supply generally consist of a main pipe entering the house and multiple branches that are distributed to each room. As we all know, when a branch is discharging water, the water inside the pipe generally only passes through the main pipe and the branch to reach the user end, and the water in other branches is in a relatively static state. If the water in the branch is not used for a long time, it is easy to deteriorate and breed bacteria, thus endangering the health of the user.

[0004] Solar energy is a clean energy that can be used sustainably. According to statistics from the IEA SHC TCP, in 2022, the installed capacity of household solar thermal systems that provide domestic hot water or heating for single-family homes accounted for about 60% of the total installed capacity of solar thermal systems worldwide. Taking China as an example, the annual new collector area and proportion of different types of solar thermal collectors from 2004 to 2023 are shown in the attached figure. Figure 4 shown.

[0005] Solar water heating system is the main form of solar thermal utilization in China. It is a device that uses solar energy to heat water and store it in a water tank for use.

[0006] Take the common household direct-plug solar vacuum water heater as an example. When it is working, the vacuum tube is filled with water, which mainly plays a role in heat conduction and cannot flow completely, similar to "dead water". After a period of use, scale will accumulate at the bottom of the vacuum tube, including organic matter. When the water temperature is between 30℃ and 60℃, it is a good condition for bacteria to grow, which may cause a large number of bacteria to multiply. At the same time, nitrite is easily accumulated in the vacuum tube, which is a carcinogen that is harmful to the human body. The above phenomenon leads to more serious secondary pollution of household direct-plug solar water heaters, including bacterial growth, excessive heavy metals, scale accumulation, excessive nitrite, etc. Therefore, the water heated by the solar water heater cannot be drunk directly. Even if it is used for bathing, it may cause and induce a series of diseases after bathing, such as skin itching, gynecological diseases, children's hand, mouth and foot diseases, etc. This problem is particularly serious in rural areas. In rural areas, because many places use surface water or even river water as the water source for solar water heaters, the water quality is complicated. This requires the hot water system to not only have the function of heating water, but also have the functions of filtering, sterilizing, removing harmful substances and regulating water quality.

[0007] Chinese patent CN202021346507.X-A live water circulation system, discloses a live water circulation system, which includes a pipe-in-pipe pipeline composed of a pipe-in-pipe and a pipe joint, the end of the pipe-in-pipe pipeline is connected to the liquid outlet device through a tail valve, and the inner cavity of the tail valve connects the inner flow channel and the outer flow channel. This technical solution can promote the regular circulation of liquid between the inner flow channel and the outer flow channel through the setting of a circulation pump, a filter, a sterilizer and a tail valve, inhibit and reduce the growth of bacteria, ensure the cleanliness and hygiene of the water source, and has excellent application effects, such as the attached Figure 2 However, there is still room for further optimization, such as reducing the cavitation phenomenon of the circulation pump, simplifying the system, and improving the flexible operation capability of the system.

[0008] Chinese patent CN202310477593.X - A pressure differential tube-in-tube liquid outlet pipeline system, discloses a tube-in-tube liquid outlet system, which includes a main pipeline, a main water inlet valve, a plurality of branches, a pressure differential liquid inlet valve core, a plurality of pressure differential liquid outlet valve cores and a plurality of water outlet devices. When the water outlet device of one or more of the branches is opened, due to the presence of the pressure differential liquid inlet valve core and the pressure differential liquid outlet valve core, a pressure difference will be generated between the inner flow channel and the outer flow channel, and the pressure of the outer flow channel will be higher than the pressure of the inner flow channel, so that in the remaining branches, the liquid in the outer flow channel can flow back to the inner flow channel through the corresponding pipeline outlet end, and finally flow out by opening the pipeline outlet end of the water outlet device. The internal water of all branches of the system can flow at any time to prevent the occurrence of dead water and deteriorated water, as shown in the attached Figure 3 However, there is still room for optimization, such as impurities in the water are not removed and a pressure differential control valve core must be used.

[0009] Chinese Patent CN201922497721.9-A directional hot water circulation control system discloses a hot water circulation control system, including a hot water source, a circulation pump, a starting valve and a pipe-in-pipe pipeline connected in sequence, and a pipe-in-pipe reflux valve is provided on the pipe-in-pipe pipeline. The opening size of the inner flow channel or the outer flow channel of the pipe-in-pipe pipeline is controlled by adjusting the valve head, and the directional circulation of the pipe-in-pipe pipeline is realized. The utility model controls the size of the inner flow channel or the outer flow channel by adjusting the valve head. When the inner flow channel or the outer flow channel is blocked, single-channel liquid discharge and directional flow can be realized; in the pipe-in-pipe pipeline, since the inner and outer flow channels are blocked, they do not participate in the circulation, which can save a large part of the energy wasted due to the circulation; when the inner and outer flow channels are opened, liquid circulation reflux can be realized, as shown in the attached Figure 5 However, there is still room for improvement, such as the impurities in the hot water and the bacteria that may grow are not removed, and the reflux valve is used.

[0010] Therefore, how to choose appropriate domestic water purification equipment to improve the quality of domestic water is worthy of in-depth study. Summary of the invention

[0011] The purpose of the present invention is to solve the above problems and provide a domestic water purification device, which adopts pipe-in-pipe and water circulation purification technology to effectively eliminate impurities, harmful ions and bacteria in domestic water, so as to improve the water quality.

[0012] A domestic water purification device, comprising: Inlet valve 41, water storage tank 43, pipe-in-pipe pipeline, external pipeline check valve 48, low-pressure end purifier 44 and / or high-pressure end purifier 46, circulating water pump 45, water use facilities, The pipe-in-pipe pipeline comprises an inner pipe 50, an outer pipe 49 and a support frame arranged between the inner and outer pipes. The inner pipeline includes an inner pipe and an inner pipe fitting, and the outer pipeline includes an outer pipe and an outer pipe fitting. The inner pipe fittings or outer pipe fittings include elbows, tees, crosses, reducers, pipe caps, etc. The support frame adopts a hollow structure and is arranged between the inner pipe and the outer pipe of the pipe-in-pipe pipeline. It adopts a separate or integrated structure with the inner pipe or the outer pipe. The integrated structure means that the support frame and the inner pipe or the outer pipe are cast together. Various types of support frames in traditional shell-and-tube heat exchangers can be applied to the pipe-in-pipe pipeline of the present invention. Domestic water enters the water storage tank 43 through the water inlet valve 41. When water facilities are out of service: Domestic water enters the outer flow channel 52 of the pipe 49 outside the pipe-in-pipe through the low-pressure end purifier 44, the circulating water pump 45, and the water supply pipe 47, and then flows back into the inner flow channel 53 of the pipe-in-pipe at the water facility, and returns to the water storage tank 43. The outer pipe check valve 48 of the pipe-in-pipe is closed. Alternatively, domestic water enters the outer flow channel 52 of the pipe 49 outside the pipe-in-pipe through the circulating water pump 45, the high-pressure end purifier 46, and the water supply pipe 47, and then flows back into the inner flow channel 53 of the pipe-in-pipe at the water-using facility, and returns to the water storage tank 43, and the outer pipe check valve 48 of the pipe-in-pipe is closed. Alternatively, the water in the water storage tank 43 enters the outer flow channel 52 of the pipe 49 outside the pipe-in-pipe through the low-pressure end purifier 44, the circulating water pump 45, and the water supply pipe 47, and then flows back into the inner flow channel 53 of the pipe-in-pipe at the water-using facility, and returns to the water storage tank 43, and the outer pipe check valve 48 of the pipe-in-pipe is closed. Alternatively, the water in the water storage tank 43 enters the outer flow channel 52 of the pipe 49 outside the pipe-in-pipe through the circulating water pump 45, the high-pressure end purifier 46, and the water supply pipe 47, and then flows back into the inner flow channel 53 of the pipe-in-pipe at the water-using facility, and returns to the water storage tank 43, and the outer pipe check valve 48 of the pipe-in-pipe is closed, thereby realizing the purification process of domestic water; When water facilities are put into operation: The outer pipe check valve 48 of the pipe-in-pipe pipeline is opened, the circulating water pump 45 is stopped, and the water in the water storage tank is supplied to the water facilities through the outer flow channel 52 and the inner flow channel 53 of the pipe-in-pipe pipeline. Or the one-way valve 48 of the outer pipe of the pipe-in-pipe pipeline is closed and the circulating water pump 45 is running, and the water in the water storage tank enters the outer flow channel 52 of the pipe 49 outside the pipe-in-pipe pipeline through the low-pressure end purifier 44, the circulating water pump 45, and the water supply pipe 47 to supply water to the water facilities, and part of the water flows back into the inner flow channel 53 of the pipe-in-pipe pipeline at the water facilities and returns to the water storage tank 43. Or the outer pipe one-way valve 48 of the pipe-in-pipe pipeline is closed and the circulating water pump 45 is running, and the water in the water storage tank enters the outer flow channel 52 of the pipe 49 outside the pipe-in-pipe pipeline through the circulating water pump 45, the high-pressure end purifier 46, and the water supply pipe 47 to supply water to the water facilities, and part of the water flows back into the inner flow channel 53 of the pipe-in-pipe pipeline at the water facilities and returns to the water storage tank 43.

[0013] The domestic water includes tap water, hot water or groundwater.

[0014] The low-pressure end purifier 44 and / or the high-pressure end purifier 46 include a filter, an ultraviolet sterilizer, an ozone sterilizer, a reverse osmosis membrane water purifier or a water softener (including a specific ion removal device, such as chloride ions, etc.).

[0015] The connections between pipes, pipes and pipe fittings, and pipe fittings and pipe fittings in the pipe-in-pipe pipeline are welded, hot-melt, expanded or threaded.

[0016] The water facilities include faucets, hot and cold water faucets, showers, washing machines, dishwashers, hot water heaters for heating, etc.

[0017] Preferably, the water inlet valve 41 is an automatic water replenishment valve, which opens to let water in when the water level in the water tank 43 is at a set low water level, and closes to stop replenishing water when the water level in the water tank 43 reaches a set high water level.

[0018] Preferably, the circulating water pump 45 is provided with a water flow switch. When the water facility uses water, the water flow switch is triggered to start the circulating water pump 45 to purify the water supply.

[0019] Preferably, when the water-using facilities are shut down, the circulating water pump 45 is started regularly to purify the water in the water storage tank 43 and the pipe-in-pipe pipeline, thereby ensuring the quality of water.

[0020] An air-water heater 59 is provided: water in the water storage tank 43 enters the air-water heater 59 through the low-pressure end purifier 44 and the circulating water pump 45 or the circulating water pump 45 and the high-pressure end purifier 46, is heated by the hot gas sent from the solar hot air heater 61, and then returns to the water storage tank 43; the hot air generated in the solar hot air heater 61 is sent to the air-water heater 59 through the gas pipeline 62 to heat the water, and the gas with reduced temperature is sent back to the solar hot air heater 61 through the fan 60, absorbs the heat of the solar energy through the heat collecting pipe in the solar hot air heater 61, and then generates hot air, thereby forming a heat utilization process of the solar energy.

[0021] Preferably, the cold water supply pipe of the gas-water heater 59 and the hot water return pipe of the water storage tank 43 adopt a pipe-in-pipe structure, thereby effectively reducing heat loss and the risk of freezing in winter.

[0022] Preferably, the gas-water heater 59 and / or the water storage tank 43 are made of stainless steel.

[0023] The outer pipe 49 of the pipe-in-pipe pipeline is provided with a support to fix the pipe-in-pipe pipeline.

[0024] Other supporting facilities of the domestic water purification device are matched with reference to or according to the reliable and mature technologies in the known pipe-in-pipe pipeline.

[0025] Compared with the prior art, the present invention has the following advantages: 1. Compared with the existing pipe-in-pipe tap water or hot water supply technology (CN202021346507.X-a live water circulation system, CN202310477593.X-a pressure differential pipe-in-pipe liquid outlet pipeline system, CN201922497721.9-a directional hot water circulation control system, etc.), the process structure of the present invention retains the advantages of the existing pipe-in-pipe water supply technology, without the need to use a pressure differential control valve or a reflux valve. Through the setting of the purifier, it can effectively ensure the water supply quality of domestic water, and the operation and adjustment are flexible and convenient; 2. Compared with the prior art, the technical solution of the present invention can be applied to both tap water supply systems and domestic hot water systems. The provision of a water storage tank can effectively reduce the cavitation phenomenon of the circulating water pump and enhance the emergency prevention capability during water outages; 3. Compared with the existing direct-insert vacuum tube solar water heater technology, the present invention adopts the water heater technology of solar hot air heater to heat water and the water purification technology, which can effectively avoid the scaling, bacteria breeding and secondary pollution of the direct-insert vacuum tube solar water heater. The hot water produced can be used for multiple purposes in life, which is safe and hygienic, and realizes the clean and efficient thermal utilization of solar energy. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 It is a structural schematic diagram of a domestic water purification device of the present invention.

[0027] Figure 1 In: 41-water inlet valve, 42-water inlet pipe, 43-water storage tank, 44-low-pressure end purifier, 45-circulating water pump, 46-high-pressure end purifier, 47-water supply pipe, 48-external pipe check valve, 49-external pipe, 50-inner pipe, 51-support frame, 52-external flow channel, 53-inner flow channel, 54-No. 1 water facility, 55-No. 2 water facility, 56-No. 3 water facility, 57-discharge valve, 58-water supply check valve, 59-gas-water heater, 60-fan, 61-solar thermal air heater, 62-gas pipe.

[0028] Figure 2 It is a structural schematic diagram of CN202021346507.X-a living water circulation system.

[0029] Figure 2 Middle: 1-tube in tube pipeline, 2-circulation pipeline, 3-circulation start valve, 6-water inlet pipe, 11-tube in tube, 12-pipe joint, 21-circulation pipe, 22-circulation pump, 23-filter, 24-ultraviolet disinfection tube, 25-water flow switch, 31-tube in tube connecting end, 32-first inner tube installation end, 33-first outer tube installation end, 36-liquid outlet one-way valve, 38-second inner tube installation end, 39-liquid inlet one-way valve.

[0030] Figure 3 It is a structural schematic diagram of CN202310477593.X-a pressure differential tube-in-tube liquid outlet pipeline system.

[0031] Figure 3 Middle: 1-main line, 2-branch line, 3-pressure differential liquid inlet valve core, 4-pressure differential liquid outlet valve core, 5-water outlet equipment, 7-main water inlet valve, 11-liquid inlet end of pipeline, 14-end pipe joint, 21-liquid outlet end of pipeline.

[0032] Figure 4 This is a diagram showing the annual new collector area and proportion of different types of solar collectors in China from 2004 to 2023.

[0033] Figure 5 It is CN201922497721.9-a structural schematic diagram of a directional hot water circulation control system.

[0034] Figure 5 Middle: 2-pipe in pipe, 100-pipe in pipe return valve, 200-hot water source, 300-circulation pump, 400-starting valve, 500-tap water pipeline, 600-controller, 700-manual delay switch, 800-induction delay switch, 801-temperature probe. DETAILED DESCRIPTION

[0035] The following is combined with Figure 1 The present invention is further described in detail with reference to the accompanying drawings and specific examples.

[0036] Embodiment 1: A domestic water purification device, comprising: Inlet valve 41, water storage tank 43, pipe-in-pipe pipeline, external pipeline check valve 48, low-pressure end purifier 44 and / or high-pressure end purifier 46, circulating water pump 45, water use facilities, The pipe-in-pipe pipeline comprises an inner pipe 50, an outer pipe 49 and a support frame arranged between the inner and outer pipes. The inner pipeline includes an inner pipe and an inner pipe fitting, and the outer pipeline includes an outer pipe and an outer pipe fitting. The inner pipe fittings or outer pipe fittings include elbows, tees, crosses, reducers, pipe caps, etc. The support frame adopts a hollow structure and is arranged between the inner pipe and the outer pipe of the pipe-in-pipe pipeline. It adopts a separate or integrated structure with the inner pipe or the outer pipe. The integrated structure means that the support frame and the inner pipe or the outer pipe are cast together. Various types of support frames in traditional shell-and-tube heat exchangers can be applied to the pipe-in-pipe pipeline of the present invention. Domestic water enters the water storage tank 43 through the water inlet valve 41. When water facilities are out of service: Domestic water enters the outer flow channel 52 of the outer pipe 49 of the pipe-in-pipe pipeline through the water inlet valve 41, the water inlet pipe 42, the low-pressure end purifier 44, the circulating water pump 45, and the water supply pipe 47, and flows back into the inner flow channel 53 of the pipe-in-pipe pipeline at the No. 1 water facility 54, the No. 2 water facility 55 or the No. 3 water facility 56, and returns to the water storage tank 43. The outer pipe check valve 48 of the pipe-in-pipe pipeline is closed. Or the domestic water enters the outer flow channel 52 of the pipe 49 outside the pipe-in-pipe through the water inlet valve 41, the water inlet pipe 42, the circulating water pump 45, the high-pressure end purifier 46, and the water supply pipe 47, and flows back into the inner flow channel 53 of the pipe-in-pipe at the No. 1 water facility 54, the No. 2 water facility 55 or the No. 3 water facility 56, and returns to the water storage tank 43, and the outer pipe check valve 48 of the pipe-in-pipe is closed. Alternatively, the water in the water storage tank 43 enters the outer flow channel 52 of the pipe 49 outside the pipe-in-pipe through the water supply check valve 58, the low-pressure end purifier 44, the circulating water pump 45, and the water supply pipe 47, and then flows back into the inner flow channel 53 of the pipe-in-pipe at the No. 1 water facility 54, the No. 2 water facility 55, or the No. 3 water facility 56, and returns to the water storage tank 43. The outer pipe check valve 48 of the pipe-in-pipe is closed. Alternatively, the water in the water storage tank 43 enters the outer flow channel 52 of the pipe 49 outside the pipe-in-pipe through the water supply check valve 58, the circulating water pump 45, the high-pressure end purifier 46, and the water supply pipe 47, and flows back into the inner flow channel 53 of the pipe-in-pipe at the No. 1 water facility 54, the No. 2 water facility 55, or the No. 3 water facility 56, and returns to the water storage tank 43, and the outer pipe check valve 48 of the pipe-in-pipe is closed, thereby realizing the purification process of domestic water; When water facilities are put into operation: The one-way valve 48 of the outer pipe of the pipe-in-pipe pipeline is opened, the circulating water pump 45 is stopped, and the water in the water storage tank is supplied to the No. 1 water-using facility 54, the No. 2 water-using facility 55 or the No. 3 water-using facility 56 through the outer flow channel 52 and the inner flow channel 53 of the outer pipe 49 of the pipe-in-pipe pipeline. Or the one-way valve 48 of the outer pipe of the pipe-in-pipe pipeline is closed and the circulating water pump 45 is running, and the water in the water storage tank enters the outer flow channel 52 of the pipe 49 outside the pipe-in-pipe pipeline through the water supply check valve 58, the low-pressure end purifier 44, the circulating water pump 45, and the water supply pipeline 47 to supply water to the No. 1 water-using facility 54, the No. 2 water-using facility 55 or the No. 3 water-using facility 56, and part of the water flows back into the inner flow channel 53 of the pipe-in-pipe pipeline at the water-using facility and returns to the water storage tank 43. Or the outer pipe one-way valve 48 of the pipe-in-pipe pipeline is closed and the circulating water pump 45 is running, and the water in the water storage tank enters the outer flow channel 52 of the pipe 49 outside the pipe-in-pipe pipeline through the water supply check valve 58, the circulating water pump 45, the high-pressure end purifier 46, and the water supply pipe 47 to supply water to the No. 1 water use facility 54, the No. 2 water use facility 55 or the No. 3 water use facility 56, and part of the water flows back into the inner flow channel 53 of the pipe-in-pipe pipeline at the water use facility and returns to the water storage tank 43.

[0037] The water storage tank 43 is provided with a discharge valve 57 for adjusting the water level of the water storage tank 43 to a suitable range when the system is put into operation.

[0038] The domestic water includes tap water, hot water or groundwater.

[0039] The low-pressure end purifier 44 and / or the high-pressure end purifier 46 include a filter, an ultraviolet sterilizer, an ozone sterilizer, a reverse osmosis membrane water purifier, and a water softener (including a specific ion removal device, such as chloride ions, etc.).

[0040] The connections between pipes, pipes and pipe fittings, and pipe fittings and pipe fittings in the pipe-in-pipe pipeline are welded, hot-melt, expanded or threaded.

[0041] The water facilities include faucets, hot and cold water faucets, showers, washing machines, dishwashers, hot water heaters for heating, etc.

[0042] Preferably, the water inlet valve 41 is an automatic water replenishment valve, which opens to let water in when the water level in the water tank 43 is at a set low water level, and closes to stop replenishing water when the water level in the water tank 43 reaches a set high water level.

[0043] Preferably, the circulating water pump 45 is provided with a water flow switch. When the water facility uses water, the water flow switch is triggered to start the circulating water pump 45 to purify the water supply.

[0044] Preferably, when the water-using facilities are shut down, the circulating water pump 45 is started regularly to purify the water in the water storage tank 43 and the pipe-in-pipe pipeline, thereby ensuring the quality of water.

[0045] An air-water heater 59 is provided: water in the water storage tank 43 enters the air-water heater 59 through the low-pressure end purifier 44 and the circulating water pump 45 or the circulating water pump 45 and the high-pressure end purifier 46, is heated by the hot gas sent from the solar hot air heater 61, and then returns to the water storage tank 43; the hot air generated in the solar hot air heater 61 is sent to the air-water heater 59 through the gas pipeline 62 to heat the water, and the gas with reduced temperature is sent back to the solar hot air heater 61 through the fan 60, absorbs the heat of the solar energy through the heat collecting pipe in the solar hot air heater 61, and then generates hot air, thereby forming a heat utilization process of the solar energy.

[0046] Preferably, the cold water supply pipe of the gas-water heater 59 and the hot water return pipe of the water storage tank 43 adopt a pipe-in-pipe structure, thereby effectively reducing heat loss and the risk of freezing in winter.

[0047] The outer pipe 49 of the pipe-in-pipe pipeline is provided with a support to fix the pipe-in-pipe pipeline.

[0048] Other supporting facilities of the domestic water purification system are matched with reference to or according to the reliable and mature technologies in the known pipe-in-pipe pipeline.

[0049] Although the present invention has been disclosed as above with preferred embodiments, they are not intended to limit the present invention. Anyone familiar with the art can make various changes or modifications without departing from the spirit and scope of the present invention, which also belong to the protection scope of the present invention. Therefore, the protection scope of the present invention shall be based on the definition of the claims of this application.

Claims

1. A domestic water purification device, characterized in that: include: Inlet valve (41), water storage tank (43), pipe-in-pipe pipeline, external pipeline check valve (48), low-pressure end purifier (44) and / or high-pressure end purifier (46), circulating water pump (45), water use facilities, The pipe-in-pipe pipeline comprises an inner pipe (50), an outer pipe (49), and a support frame arranged between the inner and outer pipes. The inner pipeline includes an inner pipe and an inner pipe fitting, and the outer pipeline includes an outer pipe and an outer pipe fitting. The support frame adopts a hollow structure and is arranged between the inner pipe and the outer pipe of the pipe-in-pipe pipeline. Domestic water enters the water storage tank (43) through the water inlet valve (41). When water facilities are out of service: The domestic water enters the outer flow channel (52) of the pipe (49) outside the pipe-in-pipe pipeline through the low-pressure end purifier (44) and the circulating water pump (45), and then flows into the inner flow channel (53) of the pipe-in-pipe pipeline at the water-using facility and returns to the water storage tank (43). The outer pipe check valve (48) of the pipe-in-pipe pipeline is closed. Alternatively, the domestic water enters the outer flow channel (52) of the pipe (49) outside the pipe-in-pipe pipeline through the circulating water pump (45) and the high-pressure end purifier (46), flows back into the inner flow channel (53) of the pipe-in-pipe pipeline at the water-using facility, and returns to the water storage tank 43. The outer pipe check valve (48) of the pipe-in-pipe pipeline is closed. Alternatively, the water in the water storage tank (43) enters the outer flow channel (52) of the pipe (49) outside the pipe-in-pipe pipeline through the low-pressure end purifier (44) and the circulating water pump (45), and then flows back into the inner flow channel (53) of the pipe-in-pipe pipeline at the water-using facility and returns to the water storage tank (43). The outer pipe check valve (48) of the pipe-in-pipe pipeline is closed. Alternatively, the water in the water storage tank (43) enters the outer flow channel (52) of the pipe (49) outside the pipe-in-pipe pipeline through the circulating water pump (45) and the high-pressure end purifier (46), and then flows back into the inner flow channel (53) of the pipe-in-pipe pipeline at the water-using facility and returns to the water storage tank (43). The outer pipe check valve (48) of the pipe-in-pipe pipeline is closed, thereby achieving the purification process of domestic water; When water facilities are put into operation: The outer pipe check valve (48) of the pipe-in-pipe pipeline is opened, the circulating water pump (45) is stopped, and the water in the water storage tank (43) is supplied to the water supply facility through the outer flow channel (52) and the inner flow channel (53) of the pipe-in-pipe pipeline. Alternatively, the one-way valve (48) on the outer pipe of the pipe-in-pipe pipeline is closed and the circulating water pump (45) is running, and the water in the water storage tank (43) enters the outer flow channel (52) of the pipe (49) outside the pipe-in-pipe pipeline through the low-pressure end purifier (44) and the circulating water pump (45) to supply water to the water facilities, and part of the water flows back into the inner flow channel (53) of the pipe-in-pipe pipeline at the water facilities and returns to the water storage tank (43). Alternatively, the one-way valve (48) on the outer pipe of the pipe-in-pipe pipeline is closed and the circulating water pump (45) is running, and the water in the water storage tank (43) enters the outer flow channel (52) of the pipe (49) outside the pipe-in-pipe pipeline through the circulating water pump (45) and the high-pressure end purifier (46) to supply water to the water-using facilities, and part of the water flows back into the inner flow channel (53) of the pipe-in-pipe pipeline at the water-using facilities and returns to the water storage tank (43).

2. The domestic water purification device according to claim 1, characterized in that: The connections between pipes, pipes and pipe fittings, and pipe fittings and pipe fittings in the pipe-in-pipe pipeline are welded, hot-melt, expanded or threaded.

3. The domestic water purification device according to claim 1, characterized in that: The low-pressure end purifier (44) and / or the high-pressure end purifier (46) include a filter, an ultraviolet sterilizer, an ozone sterilizer, a reverse osmosis membrane water purifier or a water softener.

4. The domestic water purification device according to claim 1, characterized in that: The water facilities include faucets, hot and cold water faucets, showers, washing machines, dishwashers, and hot water heaters for heating.

5. The domestic water purification device according to claim 1, characterized in that: The water inlet valve (41) is an automatic water replenishment valve, which opens to allow water to enter when the water level in the water storage tank (43) is at a set low water level, and closes to stop replenishing water when the water level in the water storage tank (43) reaches a set high water level.

6. The domestic water purification device according to claim 1, characterized in that: The circulating water pump (45) is provided with a water flow switch. When the water-using facility uses water, the water flow switch is activated to start the circulating water pump (45) to purify the supplied water.

7. The domestic water purification device according to claim 1, characterized in that: When the water-using facility is out of service, the circulating water pump (45) is started at a fixed time to purify the water in the water storage tank (43) and the pipe-in-pipe pipeline.

8. The domestic water purification device according to claim 1, characterized in that: An air-water heater (59) is provided: water in the water storage tank (43) enters the air-water heater (59) through a low-pressure end purifier (44) and a circulating water pump (45) or a circulating water pump (45) and a high-pressure end purifier (46), is heated by hot gas sent from a solar hot air heater (61), and then returns to the water storage tank (43); hot air generated in the solar hot air heater (61) is sent to the air-water heater (59) through a gas pipeline (62) to heat water, and the gas with a lowered temperature is sent back to the solar hot air heater (61) through a fan (60), absorbs solar energy heat through a heat collecting pipe in the solar hot air heater (61), and then generates hot air, thereby forming a solar energy heat utilization process.

9. The domestic water purification device according to claim 8, characterized in that: The cold water supply pipe of the gas-water heater (59) and the hot water return pipe of the water storage tank (43) adopt a pipe-in-pipe structure.

10. The domestic water purification device according to claim 8, characterized in that: The gas-water heater (59) and / or the water storage tank (43) are made of stainless steel.

Images