Domestic water purification system

Abstract

The utility model relates to a domestic water purification system which comprises a water inlet valve, a water storage tank, a pipe-in-pipe pipeline, an inner pipeline check valve, a low-pressure end purifier and / or a high-pressure end purifier, a circulating water pump and a water utilization facility. When the water utilization facility is stopped, domestic water enters the inner flow channel of the inner pipeline of the pipe-in-pipe pipeline through the low-pressure end purifier and the circulating water pump, turns over at the water utilization facility to enter the outer flow channel of the pipe-in-pipe pipeline and returns to the water storage tank, and the inner pipeline check valve of the pipe-in-pipe pipeline is closed; when the water utilization facility is put into operation, the inner pipeline check valve of the pipe-in-pipe pipeline is opened, the circulating water pump stops operating, and water in the water storage tank is supplied to the water utilization facility through the outer flow channel and the inner flow channel of the pipe-in-pipe pipeline. Impurities, harmful ions and bacteria in domestic water are removed by adopting the purifier, and the water supply quality of the domestic water is effectively improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of domestic water, and particularly relates to a domestic water purification system adopting a purification water circulation technology. BACKGROUND

[0002] With the improvement of people's living standards, the requirement for the quality of life is also getting higher and higher, for example, the quality of water.

[0003] The pipeline of general domestic water of ordinary family is composed of one main pipeline into the house and multiple branch pipelines distributed to each room. As known, when a branch pipeline is used to discharge water, the water in the pipeline generally only passes through the main pipeline and the branch pipeline to reach the user end, and the water in other branch pipelines is in a relatively static state. If the water in the branch pipeline 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 the statistical data of IEA SHC TCP, in 2022, the installed capacity of household solar heat utilization systems for providing domestic hot water or heating for single-family houses accounted for about 60% of the total installed capacity of global solar heat utilization systems. Taking China as an example, the annual newly added collector area and the proportion of different types of solar collectors from 2004 to 2023 are as shown in the accompanying Figure 4

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

[0006] Taking a common household direct-insert type solar vacuum water heater as an example, when it works, the vacuum tube is filled with water, which mainly plays a heat conduction role and cannot flow completely, similar to "dead water". After a period of use, scale will accumulate at the bottom of the vacuum tube, which contains organic matter. When the water temperature is between 30℃ and 60℃, it is a good condition for bacteria to breed, which may cause a large number of bacteria to breed. At the same time, the accumulation of nitrite, a carcinogenic substance harmful to the human body, is easy to occur in the vacuum tube. The above phenomena lead to serious secondary pollution of household direct-insert type solar water heaters, including bacterial breeding, heavy metal exceeding standard, scale accumulation, nitrite exceeding standard, etc. Therefore, the water heated by the solar water heater cannot be directly drunk, even if it is used for bathing, it may also cause or induce a series of diseases, such as skin itching, gynecological diseases, and pediatric hand-foot diseases. This problem is particularly serious in rural areas. In rural areas, because surface water or even river water is used as the water source of the solar water heater in many places, the water quality is complex, which requires the hot water system not only to have the function of heating water, but also to have the functions of filtering, sterilizing, removing harmful substances, and adjusting water quality.

[0007] ​Chinese patent CN202021346507.X - A circulating water system, discloses a circulating water system, which includes a pipe-in-pipe pipeline composed of a pipe-in-pipe and a pipe joint, the tail valve at the end of the pipe-in-pipe pipeline is connected to the liquid outlet device, and the inner cavity of the tail valve is connected to the inner flow channel and the outer flow channel. The technical scheme can promote the timed circulation of the liquid between the inner flow channel and the outer flow channel through the setting of the circulating pump, the filter, the sterilizer and the tail valve, inhibit and reduce the breeding of bacteria, ensure the cleanliness and hygiene of the water source, and has excellent application effect, as shown in the accompanying Figure 2 But there is still room for further optimization, such as reducing the cavitation phenomenon of the circulating pump, simplifying the system, and improving the flexible operation ability of the system.

[0008] Chinese patent CN202310482556.8 - Passive differential pipe-in-pipe liquid outlet system, discloses a pipe-in-pipe liquid outlet system, which includes a main pipeline, a total water inlet valve, a plurality of branches, a differential pressure liquid inlet valve core, a plurality of differential pressure liquid outlet valve cores and a plurality of water outlet devices. When one or more of the branches are opened, the pressure difference between the inner flow channel and the outer flow channel is generated due to the presence of the differential pressure liquid inlet valve core and the differential pressure liquid outlet valve core, and the pressure of the inner flow channel is higher than that of the outer flow channel, so that the liquid in the inner flow channel can flow back to the outer flow channel through the corresponding pipe outlet end in the remaining branches, and finally flow out through the pipe outlet end of the opened water outlet device. The internal water of all branches of the system can flow at any time, preventing the occurrence of dead water and deteriorated water, as shown in the accompanying Figure 3 But there is still room for optimization, such as the impurities in the water are not removed, and the differential pressure 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, which includes a hot water source, a circulating pump, a starting valve and a pipe-in-pipe pipeline connected in sequence, and a pipe-in-pipe backflow valve is arranged 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 directional circulation of the pipe-in-pipe pipeline is realized. The size of the inner flow channel or the outer flow channel is controlled by adjusting the valve head, and when the inner flow channel or the outer flow channel is blocked, unidirectional flow and directional flow can be realized; in the pipe-in-pipe pipeline, the inner and outer flow channels are blocked, so they do not participate in circulation, which can save a large part of energy wasted by circulation; when the inner and outer flow channels are opened, liquid circulation backflow can be realized, as shown in the accompanying Figure 5 But there is still room for optimization, such as the impurities in the hot water and the possible breeding of bacteria are not removed, and the backflow valve is used.

[0010] Therefore, how to choose a suitable domestic water purification system to improve the quality of domestic water is worth further studying. SUMMARY

[0011] The present application aims to solve the above problems, and provides a domestic water purification system, which adopts a pipe-in-pipe and water circulation purification technology, effectively eliminates impurities, harmful ions and bacteria in domestic water, and achieves the purpose of improving water quality.

[0012] A domestic water purification system comprises:

[0013] a water inlet valve 41, a water storage tank 43, a pipe-in-pipe pipeline, an inner pipeline check valve 48, a low-pressure end purifier 44 and / or a high-pressure end purifier 46, a circulating water pump 45, and a water using facility,

[0014] The pipe-in-pipe pipeline comprises an inner pipeline 50, an outer pipeline 49, and a support frame arranged between the inner pipeline and the outer pipeline,

[0015] The inner pipeline comprises an inner pipe and an inner fitting, and the outer pipeline comprises an outer pipe and an outer fitting,

[0016] The inner fitting or the outer fitting comprises an elbow, a tee, a cross, a reducer, a pipe cap, etc.,

[0017] The support frame adopts a hollow structure, is arranged between the inner pipeline and the outer pipeline of the pipe-in-pipe pipeline, and adopts a split or integrated structure with the inner pipeline or the outer pipeline. The integrated structure refers to that the support frame is cast together with the inner pipeline or the outer pipeline. Various types of support frames in a conventional double-pipe heat exchanger can be applied to the pipe-in-pipe pipeline of the present application,

[0018] Domestic water enters the water storage tank 43 through the water inlet valve 41,

[0019] When the water using facility is not in use:

[0020] Domestic water enters the inner flow channel 53 of the inner pipeline 50 of the pipe-in-pipe pipeline through the low-pressure end purifier 44, the circulating water pump 45, and the water supply pipeline 47, is turned over into the outer flow channel 52 of the pipe-in-pipe pipeline at the water using facility, returns to the water storage tank 43, and the inner pipeline check valve 48 of the pipe-in-pipe pipeline is closed,

[0021] or domestic water enters the inner flow channel 53 of the inner pipeline 50 of the pipe-in-pipe pipeline through the circulating water pump 45 and the high-pressure end purifier 46, is turned over into the outer flow channel 52 of the pipe-in-pipe pipeline at the water using facility, returns to the water storage tank 43, and the inner pipeline check valve 48 of the pipe-in-pipe pipeline is closed,

[0022] or water in the water storage tank 43 enters the inner flow channel 53 of the inner pipeline 50 of the pipe-in-pipe pipeline through the low-pressure end purifier 44 and the circulating water pump 45, is turned over into the outer flow channel 52 of the pipe-in-pipe pipeline at the water using facility, returns to the water storage tank 43, and the inner pipeline check valve 48 of the pipe-in-pipe pipeline is closed,

[0023] Or the water in the water storage tank 43 is pumped by the circulating water pump 45, the high-pressure end purifier 46 and the water supply pipeline 47 into the inner flow channel 53 of the inner pipeline 50 of the pipe-in-pipe pipeline, and then flows back to the water storage tank 43 through the outer flow channel 52 of the pipe-in-pipe pipeline, so as to realize the purification process of the domestic water.

[0024] When the water-using facility is put into operation:

[0025] When the water-using facility is put into operation:

[0026] When the water-using facility is put into operation:

[0027] When the water-using facility is put into operation:

[0028] The domestic water includes tap water, hot water or underground water, etc.

[0029] 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 chlorine ion, etc.).

[0030] The connection between the pipes, between the pipe and the pipe fitting, and between the pipe fittings in the pipe-in-pipe pipeline is achieved by welding, hot melt connection, expansion joint or threaded connection.

[0031] The water-using facility includes a faucet, a hot and cold water faucet, a shower, a washing machine, a dishwasher, a hot water heater for heating, etc.

[0032] Preferably, the water inlet valve 41 is an automatic water replenishment valve, which is opened when the water level in the water storage tank 43 is at a set low water level, and is closed when the water level in the water storage tank 43 reaches a set high water level, so as to stop water replenishment.

[0033] Preferably, the circulating water pump 45 is provided with a water flow switch, which is triggered when the water-using facility uses water, so as to start the circulating water pump 45 and perform the purification treatment of the water supply.

[0034] Preferably, during the shutdown of the water facility, the circulating water pump 45 is started in time to purify the water in the water storage tank 43 and the pipe-in-pipe pipeline, thereby ensuring the quality of the water.

[0035] A gas-water heater 59 is provided: the water in the water storage tank 43, through the low-pressure end purifier 44, the circulating water pump 45 or the circulating water pump 45, the high-pressure end purifier 46, enters the gas-water heater 59, is heated by the hot gas sent by the solar hot air generator 61, and returns to the water storage tank 43; the hot air generated in the solar hot air generator 61 is sent to the gas-water heater 59 to heat the water through the gas pipeline 62, the gas with reduced temperature is sent back to the solar hot air generator 61 through the fan 60, absorbs the heat of solar energy through the heat collecting pipe in the solar hot air generator 61, and generates hot air again, thereby forming a solar heat utilization process.

[0036] Preferably, the cold water supply pipeline and the hot water return pipeline of the gas-water heater 59 adopt a pipe-in-pipe structure, thereby effectively reducing heat loss and the risk of freezing in winter.

[0037] Preferably, the gas-water heater 59 and / or the water storage tank 43 adopt stainless steel materials.

[0038] The outer pipeline 49 of the pipe-in-pipe pipeline is provided with a support for fixing the pipe-in-pipe pipeline.

[0039] Other supporting facilities of the domestic water purification system refer to or are matched according to reliable and mature technologies in the pipe-in-pipe pipeline.

[0040] Compared with the prior art, the present application has the following advantages:

[0041] 1. Compared with the existing pipe-in-pipe water supply or hot water supply technology (CN202021346507.X-A living water circulation system, CN202310482556.8-Passive differential pressure pipe-in-pipe liquid outlet system, CN201922497721.9-A directional hot water circulation control system, etc.), the process structure of the present application retains the advantages of the existing pipe-in-pipe water supply technology, and does not need to use a differential pressure control valve or a backflow valve. Through the setting of the purifier, the water supply quality of domestic water can be effectively guaranteed, and the operation adjustment is flexible and convenient.

[0042] 2. Compared with the prior art, the technical scheme of the present application can be applied to a tap water supply system and a domestic hot water system. The setting of the water storage tank can effectively reduce the cavitation phenomenon of the circulating water pump and enhance the emergency prevention ability during water shutdown.

[0043] 3. Compared with the existing direct insertion type vacuum tube solar water heater technology, the water heater technology of the application uses solar hot air generator hot air to heat water, and the water purification technology can effectively avoid the scaling, bacterial breeding and secondary pollution of the direct insertion type vacuum tube solar water heater, and the produced hot water can be used for multiple purposes in life, safe and sanitary, and the clean and efficient heat utilization of solar energy is realized. BRIEF DESCRIPTION OF DRAWINGS

[0044] Figure 1 is a structure diagram of a water purification system for daily use.

[0045] Figure 1 In the figure: 41 is an inlet valve, 42 is an inlet pipeline, 43 is a water storage tank, 44 is a low-pressure end purifier, 45 is a circulating water pump, 46 is a high-pressure end purifier, 47 is a water supply pipeline, 48 is an inner pipeline check valve, 49 is an outer pipeline, 50 is an inner pipeline, 51 is a support frame, 52 is an outer flow channel, 53 is an inner flow channel, 54 is a first water use facility, 55 is a second water use facility, 56 is a third water use facility, 57 is a discharge valve, 58 is a water supply check valve, 59 is a gas-water heater, 60 is a fan, 61 is a solar hot air generator, and 62 is a gas pipeline.

[0046] Figure 2 is a structure diagram of a CN202021346507.X-structure diagram of a circulating water system.

[0047] Figure 2 In the figure: 1 is a pipe-in-pipe pipeline, 2 is a circulating pipeline, 3 is a circulating start valve, 4 is a tail valve, 5 is a liquid outlet device, 6 is a water inlet pipe, 11 is a pipe-in-pipe, 12 is a pipe joint, 21 is a circulating pipe, and 22 is a circulating pump.

[0048] Figure 3 is a structure diagram of CN202310482556.8-passive differential pressure type pipe-in-pipe liquid outlet system.

[0049] Figure 3 In the figure: 1 is a main pipeline, 2 is a branch pipeline, 3 is a differential pressure liquid inlet valve core, 4 is a differential pressure liquid outlet valve core, 5 is a water outlet device, 7 is a total water inlet valve, 11 is a pipeline liquid inlet end, 14 is an end pipe joint, and 21 is a pipeline liquid outlet end.

[0050] Figure 4 is a chart showing the annual increase in collector area and the proportion of different types of solar collectors in China from 2004 to 2023.

[0051] Figure 5 is a structure diagram of CN201922497721.9-directional hot water circulation control system.

[0052] Figure 5Fig. 1 is a schematic diagram of the water purification system of the present application, wherein: 2 - pipe-in-pipe pipeline, 100 - pipe-in-pipe backflow valve, 200 - hot water source, 300 - circulating pump, 400 - starting valve, 500 - tap water pipeline, 600 - controller, 700 - manual delay switch, 800 - inductive delay switch, 801 - temperature probe. DETAILED DESCRIPTION

[0053] The present application will be further described in detail below with reference to the accompanying drawings and specific embodiments. Figure 1

[0054] Example 1

[0055] A domestic water purification system, comprising:

[0056] a water inlet valve 41, a water storage tank 43, a pipe-in-pipe pipeline, an inner pipeline check valve 48, a low-pressure end purifier 44 and / or a high-pressure end purifier 46, a circulating water pump 45, and a water using facility,

[0057] The pipe-in-pipe pipeline comprises an inner pipeline 50, an outer pipeline 49, and a support frame arranged between the inner and outer pipelines,

[0058] The inner pipeline comprises an inner pipe and an inner fitting, and the outer pipeline comprises an outer pipe and an outer fitting,

[0059] The inner fitting or the outer fitting comprises an elbow, a tee, a cross, a reducer, a cap, etc.,

[0060] The support frame adopts a hollow structure and is arranged between the inner and outer pipelines of the pipe-in-pipe pipeline, and adopts a split or integrated structure with the inner pipeline or the outer pipeline. The integrated structure refers to that the support frame is cast together with the inner pipeline or the outer pipeline. Various types of support frames in traditional jacketed heat exchangers can be applied to the pipe-in-pipe pipeline of the present application,

[0061] Domestic water enters the water storage tank 43 through the water inlet valve 41,

[0062] When the water using facility is not in use:

[0063] Domestic water enters the inner flow channel 53 of the inner pipeline 50 of the pipe-in-pipe pipeline through the water inlet valve 41, the water inlet pipeline 42, the low-pressure end purifier 44, the circulating water pump 45, and the water supply pipeline 47, and flows back to the water storage tank 43 through the outer flow channel 52 of the pipe-in-pipe pipeline at the first water using facility 54, the second water using facility 55, or the third water using facility 56, and the inner pipeline check valve 48 of the pipe-in-pipe pipeline is closed,

[0064] ​Or the water in the water tank 43 flows through the water supply check valve 58, the low pressure end purifier 44, the circulating water pump 45, the water supply pipeline 47 into the inner flow channel 53 of the inner pipeline 50 of the pipe-in-pipe pipeline, and flows into the outer flow channel 52 of the pipe-in-pipe pipeline at the first water using facility 54, the second water using facility 55 or the third water using facility 56, and returns to the water tank 43, and the inner pipeline one-way valve 48 of the pipe-in-pipe pipeline is closed,

[0065] Or the water in the water tank 43 flows through the water supply check valve 58, the low pressure end purifier 44, the circulating water pump 45, the water supply pipeline 47 into the inner flow channel 53 of the inner pipeline 50 of the pipe-in-pipe pipeline, and flows into the outer flow channel 52 of the pipe-in-pipe pipeline at the first water using facility 54, the second water using facility 55 or the third water using facility 56, and returns to the water tank 43, and the inner pipeline one-way valve 48 of the pipe-in-pipe pipeline is closed,

[0066] Or the water in the water tank 43 flows through the water supply check valve 58, the low pressure end purifier 44, the circulating water pump 45, the water supply pipeline 47 into the inner flow channel 53 of the inner pipeline 50 of the pipe-in-pipe pipeline, and flows into the outer flow channel 52 of the pipe-in-pipe pipeline at the first water using facility 54, the second water using facility 55 or the third water using facility 56, and returns to the water tank 43, and the inner pipeline one-way valve 48 of the pipe-in-pipe pipeline is closed,

[0067] When the water using facility is put into operation:

[0068] The inner pipeline one-way valve 48 of the pipe-in-pipe pipeline is opened, and the circulating water pump 45 is stopped, and the water in the water tank flows through the outer flow channel 52 and the inner flow channel 53 of the outer pipeline 49 of the pipe-in-pipe pipeline to supply water to the first water using facility 54, the second water using facility 55 or the third water using facility 56,

[0069] Or the inner pipeline one-way valve 48 of the pipe-in-pipe pipeline is closed, and the circulating water pump 45 is operated, and the water in the water tank flows through the water supply check valve 58, the low pressure end purifier 44, the circulating water pump 45, the water supply pipeline 47 into the inner flow channel 53 of the inner pipeline 50 of the pipe-in-pipe pipeline to supply water to the first water using facility 54, the second water using facility 55 or the third water using facility 56, and part of the water flows into the outer flow channel 52 of the pipe-in-pipe pipeline at the water using facility and returns to the water tank 43,

[0070] Or the inner pipeline one-way valve 48 of the pipe-in-pipe pipeline is closed, and the circulating water pump 45 is operated, and the water in the water tank flows through the water supply check valve 58, the low pressure end purifier 44, the circulating water pump 45, the water supply pipeline 47 into the inner flow channel 53 of the inner pipeline 50 of the pipe-in-pipe pipeline to supply water to the first water using facility 54, the second water using facility 55 or the third water using facility 56, and part of the water flows into the outer flow channel 52 of the pipe-in-pipe pipeline at the water using facility and returns to the water tank 43.

[0071] 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.

[0072] The domestic water includes tap water, hot water or underground water, etc.

[0073] The low-pressure end purifier 44 and the high-pressure end purifier 46 include filters, ultraviolet sterilizers, ozone sterilizers, reverse osmosis membrane water purifiers and water softeners (including specific ion removal devices such as chlorine ions, etc.).

[0074] The connections between the pipes and the pipes, the pipes and the pipe fittings, and the pipe fittings and the pipe fittings in the pipe-in-pipe pipeline are achieved by welding, hot melt connection, expansion joint or threaded connection.

[0075] The water using facilities include faucets, dual-purpose faucets, shower heads, washing machines, dishwashers and hot water heaters for heating.

[0076] Preferably, the water inlet valve 41 is an automatic water replenishment valve which is opened to replenish water when the water level in the water storage tank 43 is at a set low water level, and is closed to stop replenishing water when the water level in the water storage tank 43 reaches a set high water level.

[0077] Preferably, the circulating water pump 45 is provided with a water flow switch which is actuated to start the circulating water pump 45 to perform purification treatment of the water when the water using facilities use water.

[0078] Preferably, the circulating water pump 45 is started at regular intervals to perform purification treatment of the water in the water storage tank 43 and the pipe-in-pipe pipeline when the water using facilities are not in operation, so as to ensure the water quality.

[0079] The gas-water heater 59 is provided: the water in the water storage tank 43, after passing through the low-pressure end purifier 44, the circulating water pump 45 or the circulating water pump 45 and the high-pressure end purifier 46, enters the gas-water heater 59, is heated by the hot gas sent by the solar heat blower 61, and returns to the water storage tank 43; the hot air generated in the solar heat blower 61 is sent to the gas-water heater 59 to heat the water, the gas with reduced temperature is sent back to the solar heat blower 61 by the air blower 60, absorbs the heat of the sun through the heat collecting pipe in the solar heat blower 61, and generates hot air again, thereby forming a solar heat utilization process.

[0080] Preferably, the cold water supply pipeline and the hot water return pipeline of the gas-water heater 59 adopt a pipe-in-pipe structure, thereby effectively reducing heat loss and the risk of freezing in winter.

[0081] The outer pipeline 49 of the pipe-in-pipe pipeline is provided with a support for fixing the pipe-in-pipe pipeline.

[0082] Other facilities of the water purification system for daily use are matched with reliable and mature technology in the known pipe-in-pipe pipeline.

[0083] Although the present application has been disclosed with reference to preferred embodiments, it is not intended to limit the present application to the preferred embodiments, and any person skilled in the art, without departing from the spirit and scope of the present application, can make various changes or modifications, which are also within the scope of the present application. Therefore, the scope of the present application should be defined by the claims of the present application.

Claims

1. A domestic water purification system, characterized in that, comprising: an inlet valve (41), a water storage tank (43), a pipe-in-pipe conduit, an inner conduit check valve (48), a low-pressure end purifier (44) and / or a high-pressure end purifier (46), a circulating water pump (45), a water using facility, the pipe-in-pipe conduit comprises an inner conduit (50), an outer conduit (49) and a support frame arranged between the inner and outer conduits, the inner conduit comprises an inner pipe and an inner fitting, and the outer conduit comprises an outer pipe and an outer fitting, the support frame adopts a hollow structure and is arranged between the inner and outer conduits of the pipe-in-pipe conduit, the domestic water enters the water storage tank (43) through the inlet valve (41), when the water using facility is not in use: the domestic water enters the inner flow channel (53) of the inner conduit (50) of the pipe-in-pipe conduit through the low-pressure end purifier (44) and the circulating water pump (45), and then flows back to the water storage tank (43) through the outer flow channel (52) of the pipe-in-pipe conduit, and the inner conduit check valve (48) of the pipe-in-pipe conduit is closed, or the domestic water enters the inner flow channel (53) of the inner conduit (50) of the pipe-in-pipe conduit through the circulating water pump (45) and the high-pressure end purifier (46), and then flows back to the water storage tank (43) through the outer flow channel (52) of the pipe-in-pipe conduit, and the inner conduit check valve (48) of the pipe-in-pipe conduit is closed, or the water in the water storage tank (43) enters the inner flow channel (53) of the inner conduit (50) of the pipe-in-pipe conduit through the low-pressure end purifier (44) and the circulating water pump (45), and then flows back to the water storage tank (43) through the outer flow channel (52) of the pipe-in-pipe conduit, and the inner conduit check valve (48) of the pipe-in-pipe conduit is closed, or the water in the water storage tank (43) enters the inner flow channel (53) of the inner conduit (50) of the pipe-in-pipe conduit through the circulating water pump (45) and the high-pressure end purifier (46), and then flows back to the water storage tank (43) through the outer flow channel (52) of the pipe-in-pipe conduit, and the inner conduit check valve (48) of the pipe-in-pipe conduit is closed, thereby realizing the purification process of the domestic water; when the water using facility is in use: the inner conduit check valve (48) of the pipe-in-pipe conduit is opened, the circulating water pump (45) is stopped, and the water in the water storage tank (43) supplies the water using facility through the outer flow channel (52) and the inner flow channel (53) of the pipe-in-pipe conduit, or the inner conduit check valve (48) of the pipe-in-pipe conduit is closed, the circulating water pump (45) is operated, and the water in the water storage tank (43) supplies the water using facility through the low-pressure end purifier (44) and the circulating water pump (45), and part of the water flows back to the water storage tank (43) through the outer flow channel (52) of the pipe-in-pipe conduit, or the inner conduit check valve (48) of the pipe-in-pipe conduit is closed, the circulating water pump (45) is operated, and the water in the water storage tank (43) supplies the water using facility through the circulating water pump (45) and the high-pressure end purifier (46), and part of the water flows back to the water storage tank (43) through the outer flow channel (52) of the pipe-in-pipe conduit.

2. The domestic water purification system according to claim 1, characterized in that, the connection between the pipes and the pipes, the pipes and the fittings, the fittings and the fittings in the pipe-in-pipe pipeline is by welding, hot melt connection, expansion or threaded connection.

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

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

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

6. The domestic water purification system according to claim 1, characterized in that, the circulating water pump (45) is provided with a water flow switch, which is activated when the water-using facilities are in use, starting the circulating water pump (45) to purify the water supply.

7. The domestic water purification system according to claim 1, characterized in that, when the water-using facilities are not in operation, the circulating water pump (45) is started regularly to purify the water in the water storage tank (43) and the pipe-in-pipe pipeline.

8. The domestic water purification system according to claim 1, characterized in that, a gas-water heater (59) is provided: the water in the water storage tank (43) enters the gas-water heater (59) through the low-pressure end purifier (44), the circulating water pump (45) or the circulating water pump (45), the high-pressure end purifier (46), is heated by the hot gas sent by the solar hot air generator (61), and returns to the water storage tank (43); the hot air generated in the solar hot air generator (61) is sent to the gas-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 generator (61) through the fan (60), and the heat-absorbing tube in the solar hot air generator (61) absorbs the heat of solar energy to generate hot air, thereby forming a solar heat utilization process.

9. The domestic water purification system according to claim 8, characterized in that, the cold water supply and hot water return pipeline of the gas-water heater (59) adopts a pipe-in-pipe structure.

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

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