Energy-saving gas heating water heater based on waste heat recovery

Abstract

The invention provides an energy-saving gas heating water heater based on waste heat recovery, which belongs to the technical field of water heaters and comprises a burner assembly, a combustion chamber, a first heat exchanger, a smoke exhaust mechanism, a second heat exchanger, a heat preservation water tank, a water inlet pipe, a three-way control valve, an electric control water mixing valve, a pressure pump, a pneumatic control on-off valve, a temperature detector and a controller. The water pumping pipe is provided with an electric flow adjusting valve, the heat preservation water tank is provided with a heater with a temperature measuring function and a water level sensor, and the smoke discharging mechanism is provided with a temperature sensor. The device does not need to add a water return pipe or an additional valve, recovers hot water retained in the water outlet pipe through the pressure pump, recovers flue gas waste heat for preheating in combination with the second heat exchanger, and realizes zero cold water supply; the water flow is adjusted through double-parameter linkage of the controller, the temperature is controlled through the electric control water mixing valve, the heat energy utilization rate is increased, various residence scenes are adapted, and energy saving and practicability are both considered.

Description

Technical Field

[0001] This invention relates to the field of hot water boiler technology, and more specifically, to an energy-saving gas-fired heating hot water boiler based on waste heat recovery. Background Technology

[0002] In the field of residential heating and domestic hot water supply, gas-fired heating and hot water boilers with zero cold water supply are widely used to meet users' immediate demand for constant-temperature hot water. To achieve the "hot water on startup" function, traditional gas-fired heating and hot water boilers with zero cold water supply typically require the addition of a return water pipe to circulate and reheat stagnant cold water in the hot water pipes; or multiple control valves and circulation pumps can be added to construct a complex water circuit switching system, forcibly driving the cold water return.

[0003] However, adding a return water pipe requires secondary modifications to the house, which is not only difficult and costly to construct, but also unsuitable for already renovated residences. Adding valves and circulation pumps increases equipment complexity and failure rates; the continuous operation of the circulation pump also increases electricity consumption, and still cannot prevent the waste of heat energy caused by the direct emission of high-temperature flue gas. Furthermore, traditional zero-cold-water boilers lack efficient flue gas waste heat recovery structures; the large amount of latent heat carried by the high-temperature flue gas is directly discharged through the exhaust system, resulting in generally low heat utilization rates. Moreover, after the tap is turned off, the remaining hot water in the outlet pipe cools naturally; even if recovered through a circulation system, it requires reheating with gas, further increasing user costs. Summary of the Invention

[0004] To address the aforementioned technical problems, this invention provides an energy-saving gas-fired heating and hot water boiler based on waste heat recovery, thereby solving the technical problems of existing zero-cold-water gas-fired heating and hot water boilers, which require the installation of return water pipes or additional valves, have low waste heat utilization rates, and suffer serious waste of water resources and heat energy.

[0005] The purpose and effectiveness of the energy-saving gas-fired heating and hot water boiler based on waste heat recovery of the present invention are achieved by the following specific technical means:

[0006] This invention provides an energy-saving gas-fired heating and hot water boiler based on waste heat recovery.

[0007] An energy-saving gas-fired heating and hot water boiler based on waste heat recovery includes:

[0008] Burner assembly;

[0009] The combustion chamber is located above the burner assembly;

[0010] A first heat exchanger is installed on the combustion chamber;

[0011] The smoke exhaust mechanism is located above the combustion chamber;

[0012] The second heat exchanger is installed on the exhaust mechanism;

[0013] An insulated water tank is provided with an inlet, an outlet and a return end. A heater is provided inside the insulated water tank. The outlet of the insulated water tank is connected to the inlet of the second heat exchanger.

[0014] The water inlet pipe is equipped with a one-way valve and a water pump in sequence along the water flow direction, and its inlet is connected to the cold water pipe interface.

[0015] A three-way control valve is installed at the outlet end of the inlet pipe, and its two outlets are respectively connected to the inlet of the first heat exchanger and the inlet of the insulated water tank.

[0016] An electrically controlled mixing valve is provided with two sets of inlets and outlets. The two sets of inlets are respectively connected to the outlet of the first heat exchanger and the outlet of the insulated water tank, and the outlet is connected to the hot water pipe interface through the outlet pipe.

[0017] A booster pump, whose inlet is connected to the outlet pipe and whose outlet is connected to the return water end of the insulated water tank, is used to extract some of the stagnant hot water in the outlet pipe.

[0018] As a preferred embodiment, a pneumatic control on / off valve is installed on the water outlet pipe to maintain a low-pressure sealing state after water is pumped out of the water outlet pipe;

[0019] A temperature detector is used to detect the water temperature in the outlet pipe;

[0020] The controller is electrically connected to the water pump, the three-way control valve, the electrically controlled mixing valve, the pressurization pump, the air pressure control on / off valve, the temperature detector, and the heater.

[0021] As a preferred embodiment, the pneumatic control on / off valve is normally closed, with its opening threshold set to 0.08–0.1 MPa and its closing threshold set to 0.15–0.3 MPa, consistent with the tap water supply pressure.

[0022] The air pressure control on / off valve is linked to the pressure sensor installed on the water outlet pipe.

[0023] As a preferred embodiment, the inlet of the pumping pipe is located at 1 / 2 of the length of the outlet pipe, and the pumping pipe is equipped with a flow regulating valve to limit the pumping volume to 1 / 2 of the total water storage capacity of the outlet pipe.

[0024] In a preferred embodiment, the inlet and outlet of the insulated water tank are both located at the top, and the outlet is located at the bottom.

[0025] The heater is installed at the bottom of the insulated water tank, and the heater control logic is as follows:

[0026] When the device is in the off state, if the heater detects that the water temperature in the insulated water tank is below 35°C, the controller controls the heater to heat the water temperature in the insulated water tank to 40°C to 45°C.

[0027] As a preferred embodiment, the electrically controlled mixing valve is a temperature-controlled proportional regulating valve, which integrates a temperature feedback module to mix the water supplied by the first heat exchanger and the second heat exchanger to obtain constant temperature water.

[0028] As a preferred embodiment, the water outlet pipe is equipped with a pressure relief pipe, and the inlet of the pressure relief pipe is located between the electrically controlled mixing valve and the hot water pipe interface;

[0029] The top of the insulated water tank is provided with a pressure relief port, the outlet of the pressure relief pipe is connected to the pressure relief port of the insulated water tank, and the pressure relief pipe is provided with a pressure relief valve.

[0030] As a preferred embodiment, the three-way control valve is a proportional regulating valve, including a first state connected to the first heat exchanger, and a second state connected to the first heat exchanger and the insulated water tank. The insulated water tank is equipped with a water level sensor, and the exhaust mechanism is equipped with an exhaust temperature sensor.

[0031] As a preferred embodiment, when the water level sensor detects that the water level in the insulated water tank is lower than 50% of the rated volume, the three-way control valve switches to the second state, and 60% to 70% of the water flow is introduced into the insulated water tank.

[0032] When the water level sensor detects that the water volume in the insulated water tank is higher than 50% of the rated volume, and the exhaust temperature sensor detects that the exhaust temperature is greater than 60°C, the three-way control valve switches to the first state.

[0033] When the water level sensor detects that the water volume in the insulated water tank is higher than 50% of the rated volume, and the exhaust temperature sensor detects that the exhaust temperature is 50-60℃, the three-way control valve switches to the second state, and only 30%-40% of the water flow is introduced into the insulated water tank.

[0034] As a preferred embodiment, the control logic of the controller includes:

[0035] S1. When the faucet is turned on, the pressure sensor detects the air pressure fluctuation in the water outlet pipe, and the controller triggers the air pressure control on / off valve to open.

[0036] S2. Control the three-way control valve to distribute the water flow in the inlet pipe according to the linkage logic of water volume and flue gas temperature, so that part of the cold water enters the first heat exchanger for heating and part of the cold water is added to the insulated water tank;

[0037] S3. The electrically controlled mixing valve receives water temperature data from the temperature detector and adjusts the mixing ratio of the high-temperature hot water output from the first heat exchanger and the preheated hot water output from the insulated water tank so that the outlet water temperature reaches the set value and water is continuously supplied.

[0038] S4. When the faucet is turned off, the controller maintains the air pressure control on / off valve in the open state and starts the pressurization pump to draw half of the hot water remaining in the outlet pipe into the insulated water tank;

[0039] S5. After the pumping is completed, the controller controls the pressurization pump to stop and the air pressure control on / off valve to close, maintaining a low-pressure sealed state in the outlet pipe.

[0040] Compared with the prior art, the present invention has the following beneficial effects:

[0041] 1. This invention, through the combined use of a booster pump and an insulated water tank, eliminates the cumbersome design of traditional zero-cold-water hot water heaters that require additional return pipes or valves, thus improving the device's adaptability and practicality. The device uses the booster pump to extract half of the remaining hot water in the hot water pipe and store it in the insulated water tank after the tap is turned off, achieving the goal of "instant hot water upon startup" without requiring secondary modifications to the house. This makes the device suitable for both newly renovated and already furnished homes, enhancing its adaptability in different scenarios while simplifying the structure and reducing the failure rate.

[0042] 2. When using this device, the connection between the second heat exchanger and the insulated water tank allows for the full recovery of the latent heat of the high-temperature flue gas emitted by the exhaust system. This enables the device to preheat cold water without consuming additional energy, thus improving the thermal energy utilization rate. Furthermore, by storing the recovered residual hot water and waste heat preheated water in the insulated water tank, the device avoids waste caused by the natural cooling of residual hot water and the direct emission of waste heat from the flue gas. This reduces gas and electricity consumption, lowers user costs, and enhances the energy-saving and consumption-reducing capabilities of the device. Attached Figure Description

[0043] Figure 1 This is a schematic diagram of the assembly structure of the invention;

[0044] Figure 2 This is a schematic diagram of the disassembled structure of the invention;

[0045] Figure 3 This is a schematic diagram of the internal structure of the invention;

[0046] Figure 4This is a schematic diagram of the structure of the exhaust temperature sensor of this invention;

[0047] Figure 5 This is a schematic diagram of the water pumping pipe of the invention;

[0048] Figure 6 This is a schematic diagram of the three-way control valve of the invention;

[0049] Figure 7 This is a structural schematic diagram of the insulated water tank of this invention;

[0050] Figure 8 This is a schematic diagram of the structure of the first heat exchanger of the invention;

[0051] Figure 9 This is a top view of the invention;

[0052] Figure 10 yes Figure 9 Sectional view of section AA;

[0053] Figure 11 The principle framework diagram of the invention.

[0054] In the diagram, the correspondence between component names and their corresponding reference numerals is as follows:

[0055] 11. Burner assembly; 12. Combustion chamber; 13. First heat exchanger; 14. Exhaust system; 15. Second heat exchanger; 16. Insulated water tank; 17. Heater; 18. Electrically controlled mixing valve; 19. Three-way control valve; 21. Inlet pipe; 22. Outlet pipe; 23. Pumping pipe; 24. Pressure relief pipe; 25. Cold water pipe interface; 26. Hot water pipe interface; 27. Check valve; 28. Water pump; 29. ​​Booster pump; 31. Flow regulating valve; 32. Gas pressure control on / off valve; 33. Pressure relief valve; 34. Controller; 35. Temperature detector; 36. Pressure sensor; 37. Water level sensor; 38. Exhaust temperature sensor. Detailed Implementation

[0056] The embodiments of the present invention will be described in further detail below with reference to the accompanying drawings and examples. The following examples are used to illustrate the technical solutions of the present invention, but should not be used to limit the scope of protection of the present invention.

[0057] Example:

[0058] like Figures 1 to 11 As shown, the present invention provides an energy-saving gas-fired heating and hot water boiler based on waste heat recovery, comprising:

[0059] The burner assembly 11 uses a natural gas burner to receive instructions from the controller 34 to ignite and burn, generating a high-temperature flame to provide a heat source for subsequent heat exchange. Its combustion power can be adaptively adjusted according to water supply demand to ensure a balance between heat exchange efficiency and energy consumption.

[0060] Combustion chamber 12, located above burner assembly 11, is a closed cavity made of high-temperature resistant stainless steel. It is used to collect the high-temperature flame and flue gas generated by burner assembly 11 and guide the heat energy to be concentrated on the first heat exchanger 13 to reduce heat loss.

[0061] The first heat exchanger 13 is installed on the combustion chamber 12. It includes a coil structure that fits against the inner wall of the combustion chamber 12 and a finned condenser heat exchanger structure that is set on the top of the combustion chamber 12. Cold water flows inside the heat exchanger and rapidly heats the cold water to the set high temperature through heat exchange with the high temperature environment of the combustion chamber 12, providing the core heat source for domestic hot water supply.

[0062] The exhaust mechanism 14 is located above the combustion chamber 12 and is used to exhaust the flue gas after heat exchange in the combustion chamber 12. At the same time, it provides an installation carrier for the second heat exchanger 15. Its inner wall is insulated to prevent the flue gas heat from being lost prematurely.

[0063] The second heat exchanger 15 is installed on the flue gas exhaust mechanism 14. It adopts a finned condensing heat exchanger structure, and the fins are made of 316L stainless steel. By increasing the contact area with the flue gas, it can fully absorb the residual latent heat in the flue gas, realize the secondary recovery of the waste heat of the flue gas, and improve the overall thermal energy utilization rate.

[0064] The insulated water tank 16 is made of a stainless steel inner liner wrapped with a polyurethane foam insulation layer, with a rated volume of 2-3L (adapted to auxiliary pre-storage function, not the main water storage structure). It is equipped with an inlet, an outlet and a return end. The insulated water tank 16 is equipped with a heater 17 (using an electric heating tube structure with a power of 500-800W). The outlet of the insulated water tank 16 is connected to the inlet of the second heat exchanger 15 through a high-temperature resistant water pipe, so that the water in the insulated water tank 16 can flow into the second heat exchanger 15, be preheated by the waste heat of the flue gas and then participate in the mixing.

[0065] The inlet pipe 21 is made of PPR hot water resistant pipe. Along the water flow direction, a one-way valve 27 and a water pump 28 are sequentially installed on the inlet pipe 21. The one-way valve 27 prevents backflow and avoids water contamination or pressure disturbance in the pipe. The water pump 28 is a miniature booster pump that provides power for the cold water supply through the inlet pipe 21. The inlet of the inlet pipe 21 is connected to the cold water pipe interface 25, allowing it to be connected to the household tap water system for continuous cold water supply.

[0066] The three-way control valve 19 is located at the outlet end of the inlet pipe 21. It is an electric proportional regulating valve with high response accuracy. Its two sets of outlets are connected to the inlet of the first heat exchanger 13 and the inlet of the insulated water tank 16 through pipelines, respectively. It can dynamically adjust the water flow ratio of the two sets of outlets according to the instructions of the controller 34, so as to realize the distribution of cold water in the heating branch of the first heat exchanger 13 and the water replenishment branch of the insulated water tank 16.

[0067] The electrically controlled mixing valve 18 can be a DN20 temperature-controlled proportional regulating valve with an integrated temperature feedback module. It has two sets of inlets and one outlet. The two inlets are connected to the outlet of the first heat exchanger 13 and the outlet of the insulated water tank 16 via pipelines, respectively, to high-temperature hot water and waste heat preheated hot water. The outlet is connected to the hot water pipe interface 26 via an outlet pipe 22. This electrically controlled mixing valve 18 can receive water temperature data from the temperature detector 35 and dynamically adjust the water flow ratio of the two inlets to ensure that the output water temperature is stable at the user-set value, with a fluctuation range not exceeding ±1℃.

[0068] The booster pump 29 is a DP-60 miniature DC booster pump with a power of 30W and a head of 3m. It has the dual functions of negative pressure pumping and pressurized delivery, and is suitable for the low flow and low head requirements of domestic hot water pipelines. The operating noise is ≤45dB, so as to avoid disturbing the user's life.

[0069] The inlet of the booster pump 29 is connected to the outlet pipe 22 via the pumping pipe 23. This connection allows for the collection of retained hot water at both the near and far ends of the outlet pipe 22, ensuring that the recycled water has a preheated temperature. An LXD-15 type electric proportional regulating valve is installed on the pumping pipe 23, which is electrically connected to the controller 34. The valve's opening parameters can be preset, limiting the pumping volume to half of the total water storage capacity of the outlet pipe 22 per pumping cycle. The outlet of the booster pump 29 is sealed to the return end of the insulated water tank 16 via a high-temperature resistant hose. During pumping, retained hot water is pressurized and transported to the tank for storage, preventing heat waste caused by natural cooling.

[0070] The booster pump 29 is linked with the controller 34 to achieve automatic start and stop: it is triggered by the controller 34 only after the user turns off the tap, and the pumping operation is completed in conjunction with the opening state of the air pressure control valve 32; after the pumping is completed, the controller 34 immediately controls the booster pump 29 to stop according to the preset running time or flow feedback signal, forming an operation mode of "starting on demand and pumping water in a quantitative manner", which not only ensures the waste heat recovery effect, but also reduces power consumption.

[0071] A pressure-controlled on / off valve 32 is installed on the water outlet pipe 22, located between the electrically controlled mixing valve 18 and the hot water pipe interface 26. It is a normally closed valve with an opening threshold set to 0.08-0.1 MPa and a closing threshold set to 0.15-0.3 MPa, consistent with the tap water supply pressure. It is used to maintain a low-pressure sealing state after water is pumped from the water outlet pipe 22. The pressure-controlled on / off valve 32 is linked with a pressure sensor 36 installed on the water outlet pipe 22. The pressure sensor 36 detects the air pressure inside the water outlet pipe 22 and transmits the data to the controller 34. The controller 34 controls the valve to open and close according to the air pressure change to prevent water leakage or air entry into the pipeline and ensure that the pipeline is stable when the machine is turned on next time.

[0072] Temperature detector 35, using a PT100 temperature sensor, is installed on the outlet pipe 22 near the hot water pipe interface 26. It is used to detect the outlet water temperature of the outlet pipe 22 and transmit the detection data to the controller 34 to provide temperature basis for the adjustment of the electric mixing valve 18 and the start and stop of the heater 17.

[0073] The controller 34 uses a dedicated industrial-grade microcontroller unit (MCU) as the control core, integrating signal receiving, processing and command output modules. It is electrically connected to the water pump 28, the three-way control valve 19, the electrically controlled mixing valve 18, the booster pump 29, the air pressure control on / off valve 32, the temperature detector 35, the heater 17, the water level sensor 37 and the flue gas temperature sensor 38 via wires.

[0074] like Figures 3 to 9 As shown, the inlet of the pumping pipe 23 is located at 1 / 2 of the length of the outlet pipe 22. The pumping pipe 23 is equipped with a flow regulating valve 31, which is used to limit the pumping volume to 1 / 2 of the total water storage capacity of the outlet pipe 22.

[0075] Specifically, the pumping pipe 23 uses a PPR hot water resistant pipe of the same specification as the outlet pipe 22. Its inlet end is connected to the outlet pipe 22 at half its length via a T-joint. This position can accommodate the residual hot water at both the near and far ends of the outlet pipe 22, avoiding the extraction of only cold water at the near end or residual water at the far end, ensuring that the recovered water has a certain temperature to meet the pre-storage requirements of the insulated water tank 16. The flow regulating valve 31 installed on the pumping pipe 23 is an LXD-15 type electric proportional regulating valve, which is electrically connected to the controller 34. The controller 34 can preset and store the opening parameters according to the actual pipe diameter (such as DN20) and length of the outlet pipe 22. By dynamically adjusting the cross-sectional area of ​​the water flow channel, the pumping volume in a single operation is controlled to be half of the total water storage capacity of the outlet pipe 22.

[0076] This system avoids both over-pumping of the insulated water tank 16, which could lead to overcapacity and abnormal pressure, and under-pumping of the water, which could result in the waste of hot water remaining in the pipeline. In addition, the system works in conjunction with the preset start and stop times of the booster pump 29 to form a dual guarantee of "mechanical valve limit + pump time control". This ensures that a stable and quantitative amount of hot water can be recovered each time the pump is turned off. This is matched with the volume of the insulated water tank 16 (2-3L) and the subsequent preheating logic to maintain the stability and energy efficiency of the device.

[0077] The inlet and outlet of the insulated water tank 16 are both located at the top, and its outlet is located at the bottom. The heater 17 is installed at the bottom of the insulated water tank 16. The control logic of the heater 17 is as follows: when the device is in the off state, when the heater 17 detects that the water temperature in the insulated water tank 16 is lower than 35°C, the controller 34 controls the heater 17 to heat the water temperature in the insulated water tank 16 to 40°C to 45°C.

[0078] Specifically, the return port of the insulated water tank 16 is connected to the outlet of the booster pump 29, and the inlet of the insulated water tank 16 is connected to the outlet of the three-way control valve 19. The inlet directions of the two are opposite, which can avoid the stratification of replenished and recycled hot water and ensure that the water temperature in the insulated water tank 16 is uniform. The outlet of the insulated water tank 16 is located at the bottom of the tank, near the bottom of the inner tank, which can maximize the discharge of preheated hot water, avoid the accumulation of cold water residue, and ensure that the temperature of the water participating in the mixing meets the standard.

[0079] The heater 17 uses a DJR-05 integrated stainless steel electric heating tube with built-in temperature detection function, with a power of 500-800W. It is embedded in the bottom inner liner of the insulated water tank 16. The heating tube has a built-in PT100 temperature sensor element, which can monitor the water temperature in the tank without relying on an external temperature detector 35, simplifying the wiring connection and improving the temperature detection accuracy. Its control logic is linked with the controller 34 to achieve automated operation: when the device is in the off state, the built-in temperature sensor of the heater 17 continuously collects water temperature data and transmits it to the controller 34. If the water temperature is detected to be below 35℃, the controller 34 immediately sends a start command, and the heater 17 starts to work; when the water temperature rises to the preset range of 40℃-45℃, the built-in sensor feeds back a compliance signal, and the controller 34 triggers the heater 17 to stop, forming a closed-loop control.

[0080] The electrically controlled mixing valve 18 is a temperature-controlled proportional regulating valve with an integrated temperature feedback module, which is used to mix the water supplied by the first heat exchanger 13 and the second heat exchanger 15 to obtain constant temperature water.

[0081] Specifically, the electrically controlled mixing valve 18 uses a DN20 temperature-controlled proportional regulating valve (model: MXF-20). The main body is made of brass, suitable for domestic hot water pipe pressure scenarios. It has two inlets and one outlet, with a sealing rating of IP65, capable of withstanding water temperatures up to 80℃, ensuring long-term stable operation. Internally, it integrates a high-precision PT100 temperature feedback module and an electric regulating valve core, eliminating the need for external detection components. It can collect water temperature data from its own outlet, achieving integrated control of "detection-regulation-temperature control".

[0082] The valve's two inlets are connected to the outlets of the first heat exchanger 13 and the second heat exchanger 15 respectively via high-temperature resistant pipelines, corresponding to high-temperature hot water (60-80℃) and flue gas waste heat preheated hot water (40-50℃). The outlet is connected to the outlet pipe 22, delivering constant-temperature hot water to the user. During operation, the internal temperature feedback module collects water temperature data once per second and compares it with the user's preset water temperature value (e.g., 45℃, 50℃) on the controller 34. The electric valve core dynamically adjusts the water flow ratio of the two inlets—if the water temperature is too high, the flow rate of preheated hot water in the second heat exchanger 15 is increased, and the proportion of high-temperature water in the first heat exchanger 13 is decreased; if the water temperature is too low, the reverse adjustment is performed, always controlling the outlet water temperature within the set value ±0.5℃ range, outputting constant-temperature water.

[0083] Meanwhile, the electronically controlled mixing valve 18 is bidirectionally linked with the controller 34. It can receive start / stop and water temperature setting commands from the controller 34, and can also provide feedback on its own operating status and water temperature data. It is compatible with the automatic control logic of the whole machine, which simplifies the pipeline layout and external line connection, improves the response speed and accuracy of constant temperature water supply, avoids the impact of water temperature fluctuations on the user experience, and adapts to the diverse needs of domestic hot water.

[0084] The outlet pipe 22 is equipped with a pressure relief pipe 24, and the inlet of the pressure relief pipe 24 is located between the electric mixing valve 18 and the hot water pipe interface 26.

[0085] The top of the insulated water tank 16 is provided with a pressure relief port, the outlet of the pressure relief pipe 24 is connected to the pressure relief port of the insulated water tank 16, and the pressure relief pipe 24 is provided with a pressure relief valve 33.

[0086] Specifically, the pressure relief pipe 24 is made of DN15 PPR hot water resistant pipe of the same specification as the outlet pipe 22. Its inlet is connected to the outlet pipe 22 section between the electric mixing valve 18 and the hot water pipe interface 26 through a tee connector. This position can directly capture the instantaneous overpressure water at the end of the water supply, avoiding overpressure impact on the user's faucet or pipe joint.

[0087] The outlet of the pressure relief pipe 24 is sealed and connected to the pressure relief port pre-set on the top of the insulated water tank 16 through a threaded joint. The pipeline is equipped with an A28H-16 type brass spring-loaded pressure relief valve 33, whose opening pressure is preset to 0.35MPa, which is suitable for the domestic tap water supply pressure range (0.15-0.3MPa). This ensures that the pressure relief valve 33 is normally closed during normal water supply and only opens automatically when the pressure in the pipeline exceeds the threshold due to a sudden increase in water temperature or valve misoperation.

[0088] When the pressure in the outlet pipe 22 exceeds the standard, the valve core of the pressure relief valve 33 is opened under pressure, and the overpressurized water flows back to the insulated water tank 16 through the pressure relief pipe 24 for recycling. This avoids the risk of pipeline leakage and bursting due to overpressure and also prevents water waste. After the pipeline pressure drops back to a safe range, the pressure relief valve 33 automatically closes and the normal water supply is restored.

[0089] This application combines the pressure relief and return flow with the water storage function of the insulated water tank 16. Compared with the traditional solution of directly depressurizing to the sewer, it realizes the secondary utilization of overpressured water and further improves the energy efficiency and operational safety of the whole machine.

[0090] like Figure 2 As shown, the three-way control valve 19 is a proportional regulating valve, including a first state connected to the first heat exchanger 13. The three-way control valve 19 also includes a second state connected to the first heat exchanger 13 and the insulated water tank 16. The insulated water tank 16 is equipped with a water level sensor 37, and the exhaust mechanism 14 is equipped with an exhaust temperature sensor 38.

[0091] When the water level sensor 37 detects that the water volume in the insulated water tank 16 is less than 50% of the rated volume, the three-way control valve 19 switches to the second state, and 60% to 70% of the water flow is introduced into the insulated water tank 16.

[0092] When the water level sensor 37 detects that the water volume in the insulated water tank 16 is higher than 50% of the rated volume, and the exhaust temperature sensor 38 detects that the exhaust temperature is greater than 60°C, the three-way control valve 19 switches to the first state.

[0093] When the water level sensor 37 detects that the water volume in the insulated water tank 16 is higher than 50% of the rated volume, and the exhaust temperature sensor 38 detects that the exhaust temperature is 50-60℃, the three-way control valve 19 switches to the second state, and only 30%-40% of the water flow is introduced into the insulated water tank 16.

[0094] Specifically, the three-way control valve 19 is a VEXG-20 electric proportional regulating valve with a brass body. It has two independent water outlet branches, which are connected to the inlet of the first heat exchanger 13 and the inlet of the insulated water tank 16 through DN15 high-temperature resistant pipelines, respectively. The valve response time is ≤0.5s, which can realize stepless adjustment of the water flow ratio and meet the water distribution requirements under different working conditions.

[0095] The valve's state switching and parameter adjustment are centrally controlled by controller 34. Controller 34 receives two detection signals: one is a CYW-20 capacitive water level sensor (water level sensor 37) installed inside the insulated water tank 16, which can monitor the water volume in the tank and output a liquid level percentage signal of 0-100%; the other is a WRN-101 K-type thermocouple (exhaust gas temperature sensor 38) installed inside the exhaust mechanism 14 near the second heat exchanger 15, which can collect flue gas temperature data and provide feedback on the potential for waste heat recovery.

[0096] Based on the two detection signals, the controller 34 drives the three-way control valve 19 to dynamically switch its working state according to preset logic:

[0097] When the water level sensor 37 reports that the water level in the insulated water tank 16 is less than 50% of the rated volume, it is determined that the water tank's heat storage capacity is insufficient. The controller 34 immediately drives the three-way control valve 19 to switch to the second state and distributes 60% to 70% of the water flow from the inlet pipe 21 to the inlet branch of the insulated water tank 16 to replenish the water tank's water volume first. The remaining 30% to 40% of the water flow enters the first heat exchanger 13 for heating, taking into account both immediate water supply and heat storage needs.

[0098] When the water level sensor 37 reports that the water volume is higher than 50% of the rated volume, and the flue gas temperature sensor 38 detects that the flue gas temperature is greater than 60°C, it is determined that the flue gas has little waste heat and low recovery value. The controller 34 drives the valve to switch to the first state, and all the water flow from the inlet pipe 21 enters the first heat exchanger 13 for heating, thereby improving the efficiency of the main water supply.

[0099] When the water level sensor 37 reports that the water volume is 50% higher than the rated volume, and the flue gas temperature sensor 38 detects that the flue gas temperature is in the range of 50-60℃, it is determined that the waste heat of the flue gas is sufficient. The controller 34 drives the valve to maintain the second state, and only allocates 30%-40% of the water flow to the insulated water tank 16 to preheat the water body using waste heat. The remaining water flows into the first heat exchanger 13, achieving the optimal balance between waste heat recovery and water supply efficiency.

[0100] This dual-parameter linkage control logic overcomes the limitations of traditional single-parameter regulation, achieving matching between water distribution and waste heat intensity and water storage status, thereby improving the energy efficiency and operational stability of the entire unit.

[0101] like Figure 2 , Figure 11 As shown, the control logic of controller 34 includes:

[0102] S1. When the faucet is turned on, the pressure sensor 36 detects the air pressure fluctuation in the water outlet pipe 22, and the controller 34 triggers the air pressure control on / off valve 32 to open.

[0103] S2. Control the three-way control valve 19 to distribute the water flow in the inlet pipe 21 according to the linkage logic of water volume and flue gas temperature. Part of the cold water enters the first heat exchanger 13 for heating, and part of the cold water is added to the insulated water tank 16.

[0104] S3. The electrically controlled mixing valve 18 receives water temperature data from the temperature detector 35 and adjusts the mixing ratio of the high-temperature hot water output from the first heat exchanger 13 and the preheated hot water output from the insulated water tank 16 so that the outlet water temperature reaches the set value and water is continuously supplied.

[0105] S4. When the faucet is turned off, the controller 34 maintains the air pressure control on / off valve 32 in the open state and starts the pressurization pump 29 to extract half of the hot water remaining in the water pipe 22 to the insulated water tank 16.

[0106] S5. After the pumping is completed, the controller 34 controls the pressurization pump 29 to stop and the air pressure control on / off valve 32 to close, maintaining a low-pressure sealing state in the outlet pipe 22.

[0107] Understandably, the controller 34, as the "control center" of the entire machine, uses a preset program as its core to link various detection and execution components, achieving fully automated closed-loop operation. Each step is interconnected and logically clear, ensuring both zero-cold-water supply and waste heat recovery effects, as well as operational stability. Specifically, it can be broken down into the following coherent workflow:

[0108] The controller 34 has a built-in microcontroller control core, which pre-stores the linkage parameters and thresholds of each component, receives feedback signals from the pressure sensor 36, water level sensor 37, flue gas temperature sensor 38, and temperature detector 35, and drives the actions of each actuator in an orderly manner step by step.

[0109] When the user turns on the tap (S1), the water flow in the outlet pipe 22 breaks the original pressure balance. The pressure sensor 36 (MPX5010) quickly captures the air pressure fluctuation signal and transmits it to the controller 34. The controller 34 determines that there is a water supply demand and immediately outputs a command to trigger the air pressure control on / off valve 32 to open, thus opening the outlet pipe 22 and preparing for subsequent water supply.

[0110] After the pipeline is connected (S2), the controller 34 synchronously retrieves data from the water level sensor 37 and the flue gas temperature sensor 38, and sends an adjustment command to the three-way control valve 19 according to the preset dual-parameter linkage logic. If the water tank is insufficient, water is added first; if the waste heat is sufficient, a portion of the water flow is allocated to utilize the waste heat for preheating; if the waste heat is insufficient, the main pipeline heating is fully guaranteed. By allocating the water flow through the inlet pipe 21, the three major needs of immediate water supply, water tank heat storage, and waste heat recovery are taken into account.

[0111] During the water supply process (S3), the electronically controlled mixing valve 18 and the temperature detector 35 form a feedback regulation mechanism: the temperature detector 35 continuously collects the water temperature data of the outlet pipe 22 and transmits it to the controller 34. After comparing the actual water temperature with the user-set value, the controller 34 sends an adjustment command to the electronically controlled mixing valve 18 to dynamically adjust the mixing ratio of high-temperature hot water and preheated hot water, ensuring that the outlet water temperature is stable at the set value and avoiding water temperature fluctuations from affecting the user experience.

[0112] When the user turns off the tap (S4), the pressure in the outlet pipe 22 tends to stabilize, and the controller 34 determines that the water supply has ended, but maintains the air pressure control on / off valve 32 in the open state. At the same time, the booster pump 29 is started, and the electric flow regulating valve 31 is controlled to work at the preset opening degree to extract half of the hot water remaining in the outlet pipe 22. After pressurization, it is transported to the insulated water tank 16 through the pumping pipe 23 for storage, so as to avoid the waste of heat energy caused by the natural cooling of hot water.

[0113] After the pumping is completed (S5), the controller 34 determines that the pumping is finished by the running time of the booster pump 29 (preset 10-15s, adapted to the pipeline volume) or the flow feedback signal. Then, it sends a command to control the booster pump 29 to stop and close the air pressure control on / off valve 32 at the same time, so that the outlet pipe 22 is kept in a low-pressure sealed state to prevent air from entering or water from leaking, laying the foundation for immediate water supply when the machine is turned on again.

[0114] The entire control logic forms a complete closed loop of "demand triggering - dynamic adjustment - end of recovery - standby preparation", requiring no manual intervention. It achieves the function of zero cold water without return water pipe, and maximizes the recovery of waste heat from flue gas and hot water retained in the pipeline.

[0115] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. An energy-saving gas-fired heating and hot water boiler based on waste heat recovery, characterized in that, include: Burner assembly (11); Combustion chamber (12) is disposed above the burner assembly (11); The first heat exchanger (13) is installed on the combustion chamber (12); A smoke exhaust mechanism (14) is disposed above the combustion chamber (12); The second heat exchanger (15) is installed on the exhaust mechanism (14); A water insulated tank (16) is provided with an inlet, an outlet and a return end. A heater (17) is provided inside the water insulated tank (16). The outlet of the water insulated tank (16) is connected to the inlet of the second heat exchanger (15). Water inlet pipe (21), a one-way valve (27) and a water pump (28) are sequentially provided on the water inlet pipe (21) along the water flow direction, and its inlet is connected to the cold water pipe interface (25); A three-way control valve (19) is installed at the outlet end of the water inlet pipe (21), and its two sets of outlets are respectively connected to the inlet of the first heat exchanger (13) and the inlet of the insulated water tank (16). The electric mixing valve (18) is provided with two sets of inlets and outlets. The two sets of inlets are connected to the outlet of the first heat exchanger (13) and the outlet of the insulated water tank (16) respectively. The outlet is connected to the hot water pipe interface (26) through the outlet pipe (22). A booster pump (29) has its inlet end connected to the outlet pipe (22) and its outlet end connected to the return end of the insulated water tank (16) for extracting part of the stagnant hot water in the outlet pipe (22).

2. The energy-saving gas-fired heating and hot water boiler according to claim 1, characterized in that, Also includes: A pneumatic control on / off valve (32) is installed on the water outlet pipe (22) to maintain a low-pressure sealing state after the water outlet pipe (22) is pumped out; Temperature detector (35) is used to detect the water temperature in the outlet pipe (22); The controller (34) is electrically connected to the water pump (28), the three-way control valve (19), the electric mixing valve (18), the booster pump (29), the air pressure control on / off valve (32), the temperature detector (35), and the heater (17).

3. The energy-saving gas-fired heating and hot water boiler according to claim 2, characterized in that: The pneumatic control on / off valve (32) is normally closed, with its opening threshold set to 0.08-0.1 MPa and its closing threshold set to 0.15-0.3 MPa, which is consistent with the tap water supply pressure. The air pressure control on / off valve (32) is linked to the pressure sensor (36) installed on the water outlet pipe (22).

4. The energy-saving gas-fired heating and hot water boiler according to claim 3, characterized in that: The inlet of the pumping pipe (23) is located at 1 / 2 of the length of the outlet pipe (22). The pumping pipe (23) is equipped with a flow regulating valve (31) to limit the pumping volume to 1 / 2 of the total water storage capacity of the outlet pipe (22).

5. An energy-saving gas-fired heating and hot water boiler based on waste heat recovery according to claim 4, characterized in that: The inlet and outlet of the insulated water tank (16) are both located at the top, and its outlet is located at the bottom. The heater (17) is installed at the bottom of the insulated water tank (16), and the control logic of the heater (17) is as follows: When the device is in the off state, when the heater (17) detects that the water temperature in the insulated water tank (16) is lower than 35°C, the controller (34) controls the heater (17) to heat the water temperature in the insulated water tank (16) to 40°C to 45°C.

6. The energy-saving gas-fired heating and hot water boiler based on waste heat recovery according to claim 1, characterized in that: The electrically controlled mixing valve (18) is a temperature-controlled proportional regulating valve with an integrated temperature feedback module, which is used to mix the water provided by the first heat exchanger (13) and the second heat exchanger (15) to obtain constant temperature water.

7. An energy-saving gas-fired heating and hot water boiler based on waste heat recovery according to claim 6, characterized in that: The outlet pipe (22) is provided with a pressure relief pipe (24), and the inlet of the pressure relief pipe (24) is located between the electric mixing valve (18) and the hot water pipe interface (26); The top of the insulated water tank (16) is provided with a pressure relief port, the outlet of the pressure relief pipe (24) is connected to the pressure relief port of the insulated water tank (16), and the pressure relief pipe (24) is provided with a pressure relief valve (33).

8. An energy-saving gas-fired heating and hot water boiler based on waste heat recovery according to claim 7, characterized in that: The three-way control valve (19) is a proportional regulating valve, including a first state connected to the first heat exchanger (13), and a second state connected to the first heat exchanger (13) and the insulated water tank (16). The insulated water tank (16) is equipped with a water level sensor (37), and the exhaust mechanism (14) is equipped with an exhaust temperature sensor (38).

9. An energy-saving gas-fired heating and hot water boiler based on waste heat recovery according to claim 8, characterized in that: When the water level sensor (37) detects that the water volume in the insulated water tank (16) is lower than 50% of the rated volume, the three-way control valve (19) switches to the second state, and 60% to 70% of the water flow is introduced into the insulated water tank (16). When the water level sensor (37) detects that the water volume of the insulated water tank (16) is higher than 50% of the rated volume, and the exhaust temperature sensor (38) detects that the exhaust temperature is >60℃, the three-way control valve (19) switches to the first state; When the water level sensor (37) detects that the water volume of the insulated water tank (16) is higher than 50% of the rated volume, and the exhaust temperature sensor (38) detects that the exhaust temperature is 50-60°C, the three-way control valve (19) switches to the second state, and only 30%-40% of the water flow is introduced into the insulated water tank (16).

10. An energy-saving gas-fired heating and hot water boiler based on waste heat recovery according to claims 1 to 9, characterized in that, The control logic of the controller (34) includes: S1. When the faucet is turned on, the pressure sensor (36) detects the air pressure fluctuation of the water outlet pipe (22), and the controller (34) triggers the air pressure control on / off valve (32) to open; S2. Control the three-way control valve (19) to distribute the water flow in the inlet pipe (21) according to the linkage logic of water volume and flue gas temperature. Part of the cold water enters the first heat exchanger (13) for heating, and part of the cold water is added to the insulated water tank (16). S3. The electrically controlled mixing valve (18) receives the water temperature data from the temperature detector (35), adjusts the mixing ratio of the high-temperature hot water output by the first heat exchanger (13) and the preheated hot water output by the heat preservation tank (16), so that the outlet water temperature reaches the set value and water is continuously supplied. S4. When the tap is turned off, the controller (34) maintains the air pressure control on / off valve (32) in the open state and starts the pressurization pump (29) to draw half of the hot water remaining in the outlet pipe (22) into the insulated water tank (16). S5. After the pumping is completed, the controller (34) controls the pressurizing pump (29) to stop and the air pressure control on / off valve (32) to close, maintaining a low-pressure sealing state in the outlet pipe (22).

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