Stirling and semiconductor thermoelectric cogeneration device adapting to biomass boiler waste heat

Abstract

The application discloses a kind of Stirling and semiconductor temperature difference compound micro combined heat and power device suitable for biomass boiler waste heat, it is related to waste heat recovery and micro combined heat and power technical field, solve the problem of poor adaptability, high cost, low energy utilization efficiency of existing device.The device includes waste heat collection module, Stirling power generation module, semiconductor temperature difference power generation module, waste heat recovery module, electric energy processing module and control module;Waste heat collection module is connected with biomass boiler waste heat outlet, Stirling power generation module uses piezoelectric structure without moving parts, semiconductor temperature difference power generation module uses single-stage temperature difference sheet, realize waste heat cascade recovery power generation, waste heat recovery module uses remaining waste heat for heating / heat water, control module adjusts system operating state according to waste heat parameter.The application has strong adaptability, long service life, low cost, waste heat utilization rate is improved to more than 85%, small and exquisite, easy to install, suitable for household and small commercial places of biomass boiler waste heat recovery and cogeneration.

Description

Technical Field

[0001] This invention relates to the field of waste heat recovery and micro-cogeneration technology, specifically to a Stirling and semiconductor thermoelectric composite micro-cogeneration device adapted to waste heat from biomass boilers, suitable for integrated applications of waste heat recovery power generation and heating / hot water supply in residential and small commercial settings. Background Technology

[0002] With increasing demands for energy conservation and environmental protection, biomass boilers, as clean heating equipment, are being used more and more widely in households and small parks. However, these devices generate a large amount of medium and low temperature waste heat (temperature range 80-200℃) during operation. Currently, most of this waste heat is directly discharged, resulting in energy waste.

[0003] In existing micro-cogeneration technologies, while standalone Stirling generators can generate electricity using medium- and low-temperature waste heat, traditional Stirling engines have high maintenance costs and low power generation efficiency in low-grade waste heat scenarios; standalone thermoelectric generators have limited energy conversion efficiency and are difficult to meet the power supply needs of small-scale scenarios.

[0004] Existing cogeneration units are mostly designed for a single heat source, which cannot flexibly adapt to the unstable temperature fluctuations of waste heat flow in biomass boilers, making them unsuitable for the installation and use needs of residential and small-scale commercial applications. Therefore, there is an urgent need for a micro-cogeneration unit that can adapt to the waste heat of biomass boilers, realize the cascade utilization of waste heat, and improve energy conversion efficiency. Summary of the Invention

[0005] To address the shortcomings of the existing technology, the present invention aims to provide a Stirling and semiconductor thermoelectric composite micro cogeneration device adapted to the waste heat of biomass boilers. This device solves the technical problems of poor adaptability, high maintenance costs, and low energy conversion efficiency of existing micro cogeneration devices, realizes the cascade recovery of low-temperature waste heat from biomass boilers, and combines power generation, heating / hot water supply functions. It also features a simple structure, long service life, and controllable cost.

[0006] To achieve the above objectives, the present invention adopts the following technical solution: A Stirling and semiconductor thermoelectric composite micro cogeneration device adapted to waste heat from biomass boilers includes a waste heat collection module, a Stirling power generation module, a semiconductor thermoelectric power generation module, a waste heat recovery module, an energy processing module, and a control module. The waste heat collection module includes a waste heat inlet pipe, an insulation sleeve, and a heat exchange chamber. One end of the waste heat inlet pipe is connected to the waste heat outlet of a biomass boiler or wall-hung boiler, and the other end extends into the heat exchange chamber. The insulation sleeve is fitted over the outside of the waste heat inlet pipe to reduce waste heat loss. The heat exchange chamber is filled with a high-efficiency thermally conductive medium, which is a mixture of thermally conductive oil and graphite powder, wherein the graphite powder accounts for 5%-10% of the total mass. The Stirling power generation module adopts a Stirling power generation structure without moving parts, including a cold-end heat exchanger, a hot-end heat exchanger, a heat storage body, and a power generation unit. The hot-end heat exchanger is attached to the outside of the heat exchange cavity to absorb the waste heat transferred by the heat exchange cavity. The cold-end heat exchanger is connected to the semiconductor thermoelectric power generation module. The heat storage body is set between the hot-end heat exchanger and the cold-end heat exchanger to stabilize temperature fluctuations, which is suitable for the characteristics of unstable waste heat temperature in boilers. The power generation unit adopts a piezoelectric power generation structure. The semiconductor thermoelectric power generation module is attached to the outside of the cold end heat exchanger. Its high-temperature end is in contact with the cold end heat exchanger, and its low-temperature end is in contact with the heat exchange tube of the waste heat recovery module, forming a temperature gradient to realize secondary recovery of waste heat for power generation. The semiconductor thermoelectric power generation module adopts a single-stage semiconductor thermoelectric plate, which is selected to match medium and low temperature waste heat scenarios (temperature difference 50-150℃). The waste heat recovery module includes a heat exchange tube, a water storage tank, and a circulation pump. One end of the heat exchange tube is connected to the low-temperature end of the semiconductor thermoelectric power generation module, and the other end is connected to the water storage tank. The circulation pump is installed on the heat exchange tube and is used to drive the heat exchange medium to circulate, absorb the heat from the cold end heat exchanger and the low-temperature end of the semiconductor thermoelectric power generation module, and realize the function of heating or hot water supply. The power processing module includes a rectifier, a voltage regulator, and an energy storage unit. The rectifier is electrically connected to the power generation unit of the Stirling power generation module and the semiconductor thermoelectric power generation module, respectively, and is used to convert AC power into DC power. The voltage regulator is electrically connected to the rectifier and is used to stabilize the output voltage. The energy storage unit uses a small lithium battery to store excess power and is adapted to the power fluctuation needs of households and small businesses. The control module includes a temperature sensor, a flow sensor, and a controller. The temperature sensor is located at the connection between the heat exchange chamber and the waste heat inlet pipe to detect the waste heat temperature. The flow sensor is located on the waste heat inlet pipe to detect the waste heat flow rate. The controller is electrically connected to the temperature sensor, the flow sensor, the circulating pump, and the power processing module, and is used to adjust the speed of the circulating pump and the working state of the power processing module according to changes in waste heat temperature and flow rate to ensure stable system operation and avoid energy waste.

[0007] Furthermore, the waste heat inlet pipe is made of corrosion-resistant stainless steel with a diameter of 50-80mm, which is compatible with the conventional waste heat outlet size of biomass boilers, eliminating the need for additional modifications to the heat source equipment and reducing adaptation costs; the insulation sleeve uses a rock wool insulation layer with a thickness of 10-15mm and an insulation efficiency of ≥90%, reducing waste heat loss during transmission.

[0008] Furthermore, the heat storage body of the Stirling power generation module adopts a composite heat storage material of paraffin and expanded graphite with a phase change temperature of 80-100℃. It can quickly absorb and release heat, stabilize the temperature difference between the hot end and the cold end, and avoid the decrease in power generation efficiency due to the fluctuation of waste heat from the biomass boiler. At the same time, the material is low in cost and easy to obtain.

[0009] Furthermore, a thermally conductive silicone pad is provided between the high-temperature end and the cold-end heat exchanger of the semiconductor thermoelectric power generation module, and a thermally conductive silicone pad is also provided between the low-temperature end and the heat exchange tube of the waste heat recovery module. The thickness of the thermally conductive silicone pad is 1-2mm, and the thermal conductivity is ≥2W / (m·K), thereby improving the heat transfer efficiency.

[0010] Furthermore, the waste heat recovery module's water storage tank is equipped with a temperature monitor and a water inlet. The temperature monitor is electrically connected to the controller. When the water temperature in the storage tank is lower than the set value (40-50℃), the controller adjusts the speed of the circulating pump to improve the heat exchange efficiency. The water inlet is used to replenish the lost heat exchange medium to ensure the stability of the waste heat recovery function.

[0011] Furthermore, the control module also includes a wireless communication unit, which can transmit the device's operating parameters (waste heat temperature, power generation, and water temperature in the storage tank) to a mobile terminal, facilitating remote monitoring and control by users and improving ease of use.

[0012] Furthermore, the device adopts a modular design, with each module connected by flanges, which facilitates installation, disassembly and maintenance. It is also compact in size, making it suitable for the installation space requirements of residential and small commercial spaces.

[0013] The Stirling power generation module has a power output of 50-100W, and the semiconductor thermoelectric power generation module has a power output of 20-50W.

[0014] The Stirling power generation module's power generation unit is a piezoelectric ceramic power generation component, which has no mechanical moving parts, operates without wear, and has a service life of no less than 10 years.

[0015] Compared with the prior art, the present invention has the following beneficial effects: 1. It has strong adaptability and can be directly connected to the waste heat outlet of biomass boilers without modifying the original heat source equipment. Through the cooperation of the heat storage body and the controller, it can adapt to the characteristics of large fluctuations in waste heat temperature and flow rate, solving the problem of poor adaptability of existing devices. At the same time, it can be used as a supplement to solar photovoltaic, and can operate stably when there is insufficient sunlight in winter. 2. Cost is controllable. The semiconductor thermoelectric power generation module uses a single-stage thermoelectric plate, the heat conduction medium adopts a low-cost hybrid system, and the heat storage material is a readily available composite material of paraffin and expanded graphite, resulting in a low overall cost. 3. High energy efficiency with cascaded waste heat recovery: The first stage utilizes medium-to-high temperature waste heat (120-200℃) to generate electricity through a Stirling power generation module. The second stage utilizes cold-end waste heat (80-120℃) through a semiconductor thermoelectric power generation module for secondary power generation. The remaining waste heat is used for heating and hot water supply through a waste heat recovery module, increasing the waste heat utilization rate to over 85%. This can simultaneously meet the integrated needs of power generation, heating, and hot water supply for residential and small commercial establishments. It solves the energy waste problem of existing single power generation devices. Furthermore, the Stirling module and semiconductor module work together to improve the system's flexibility in variable load operation and adapt to different operating conditions. 4. It has a simple structure and small size, adopts a modular design, is easy to install and disassemble, is suitable for residential, small shop and other scenarios, and has wireless remote monitoring function. It is easy to use and can meet the cogeneration needs of small-scale scenarios. Attached Figure Description

[0016] Figure 1 A schematic diagram of a Stirling and semiconductor thermoelectric composite micro-cogeneration unit that utilizes waste heat from biomass boilers. Detailed Implementation

[0017] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. The following embodiments are used to illustrate the present invention, but are not limited to the scope of protection of the present invention.

[0018] This embodiment provides a Stirling and semiconductor thermoelectric composite micro cogeneration device adapted to the waste heat of biomass boilers, including a waste heat collection module, a Stirling power generation module, a semiconductor thermoelectric power generation module, a waste heat recovery module, an energy processing module, and a control module.

[0019] Waste heat collection module: The waste heat inlet pipe is made of corrosion-resistant stainless steel with a diameter of 60mm. One end is connected to the waste heat outlet flange of the biomass boiler, and the other end extends into the heat exchange chamber. The insulation sleeve is made of rock wool insulation layer with a thickness of 12mm and an insulation efficiency of 92%. The heat exchange chamber is filled with a mixed heat transfer medium of heat transfer oil and graphite powder, with graphite powder accounting for 8% of the mass, ensuring heat transfer efficiency while controlling costs.

[0020] Stirling power generation module: It adopts a piezoelectric Stirling power generation structure with no moving parts. The hot-end heat exchanger is attached to the outside of the heat exchange cavity, and the cold-end heat exchanger is connected to the semiconductor power generation module. The heat storage body adopts a composite heat storage material of paraffin and expanded graphite with a phase change temperature of 90℃, which can stabilize the temperature difference between the hot and cold ends and adapt to the waste heat fluctuation characteristics of biomass boilers. The power generation unit adopts piezoelectric ceramic power generation components with an output power of 50-100W. It has no moving parts and avoids wear.

[0021] Semiconductor thermoelectric power generation module: It adopts a single-stage semiconductor thermoelectric plate, which is attached to the outside of the cold end heat exchanger. The high-temperature end contacts the cold end heat exchanger through a thermally conductive silicone pad (1.5mm thick, thermal conductivity 2.2W / (m·K)), and the low-temperature end contacts the heat exchange tube of the waste heat recovery module through a thermally conductive silicone pad of the same specification. The thermoelectric plate is a long-life model (MTBF=120000hrs), which is suitable for temperature difference scenarios of 50-150℃. The output power is 20-50W, and the cost is reduced by 35% compared with multi-stage modules, meeting the power supply needs of micro-scenario.

[0022] Waste heat recovery module: The heat exchange tube is made of copper with a diameter of 40mm. One end is connected to the low-temperature end of the semiconductor thermoelectric generator module, and the other end is connected to the water storage tank (50L capacity). The circulation pump is a small silent circulation pump with a power of 30W, and the speed is adjusted by the controller. The water storage tank is equipped with a temperature monitor and a water inlet. The temperature monitor detects the water temperature in real time. When the water temperature is lower than 45℃, the controller increases the speed of the circulation pump to ensure heating / hot water supply needs.

[0023] Power processing module: The rectifier adopts a bridge rectifier to convert the AC power output from the Stirling power generation module and the thermoelectric power generation module into DC power; the voltage regulator adopts a linear voltage regulator to stabilize the output voltage at 12V; the energy storage unit adopts a 100Ah small lithium battery to store excess power and meet the power supply needs of small household appliances (such as lamps and routers).

[0024] Control module: The temperature sensor is located at the connection between the heat exchange chamber and the waste heat inlet pipe, with a detection range of 0-250℃ and an accuracy of ±1℃; the flow sensor is located on the waste heat inlet pipe, with a detection range of 0.1-1m³ / h; the controller uses a single-chip microcomputer, model STM32F103, which is electrically connected to the temperature sensor, flow sensor, circulating pump, power processing module, and wireless communication unit (WiFi module), and can transmit operating parameters to a mobile APP for convenient remote monitoring by users.

[0025] The working process of this embodiment of the Stirling and semiconductor thermoelectric composite micro cogeneration device adapted to the waste heat of biomass boilers is as follows: The waste heat generated by the biomass boiler (temperature around 150°C) enters the heat exchange chamber through the waste heat inlet pipe. The heat transfer medium absorbs the waste heat and transfers it to the hot end heat exchanger of the Stirling power generation module. The heat storage body stabilizes the temperature fluctuations. The Stirling power generation module converts heat energy into electrical energy through the piezoelectric effect, with an output power of approximately 80W. The cold end heat exchanger absorbs the cold end heat from the Stirling power generation module, maintaining the temperature at around 100°C. The semiconductor thermoelectric power generation module utilizes the temperature difference between the cold end heat exchanger and the heat exchange tube of the waste heat recovery module (… With a temperature difference of approximately 60℃, secondary power generation is achieved through the Seebeck effect, with an output power of about 35W. After being processed by a rectifier and voltage regulator, part of the electrical energy is directly supplied to users, while excess energy is stored in a lithium battery. The circulating pump of the waste heat recovery module drives the heat exchange medium to circulate, absorbing heat from the cold end heat exchanger and the low-temperature end of the semiconductor thermoelectric power generation module, heating the water in the storage tank to about 55℃ for heating or hot water supply. The controller adjusts the speed of the circulating pump in real time based on the detection data of the temperature sensor and flow sensor to ensure stable operation of the device. When the waste heat temperature is below 100℃, the heat storage body releases heat to maintain power generation efficiency.

Claims

1. A Stirling and semiconductor thermoelectric composite micro-cogeneration device adapted to waste heat from biomass boilers, characterized in that, It includes a waste heat harvesting module, a Stirling power generation module, a semiconductor thermoelectric power generation module, a waste heat recovery module, an energy processing module, and a control module; The waste heat collection module includes a waste heat inlet pipe, an insulation sleeve, and a heat exchange chamber. One end of the waste heat inlet pipe is connected to the waste heat outlet of a biomass boiler or wall-mounted boiler, and the other end extends into the heat exchange chamber. The insulation sleeve is fitted over the outside of the waste heat inlet pipe. The heat exchange chamber is filled with a high-efficiency thermally conductive medium, which is a mixture of thermally conductive oil and graphite powder, with the graphite powder accounting for 5%-10% of the total mass. The Stirling power generation module adopts a Stirling power generation structure without moving parts, including a cold end heat exchanger, a hot end heat exchanger, a heat storage body, and a power generation unit. The hot end heat exchanger is attached to the outside of the heat exchange cavity, the cold end heat exchanger is connected to the semiconductor power generation module, and the heat storage body is disposed between the hot end heat exchanger and the cold end heat exchanger; the power generation unit adopts a piezoelectric power generation structure. The semiconductor thermoelectric power generation module is attached to the outside of the cold end heat exchanger, with its high-temperature end in contact with the cold end heat exchanger and its low-temperature end in contact with the heat exchange tube of the waste heat recovery module; the semiconductor thermoelectric power generation module adopts a single-stage semiconductor thermoelectric plate, which is suitable for temperature difference scenarios of 50-150℃. The waste heat recovery module includes a heat exchange tube, a water storage tank, and a circulation pump. One end of the heat exchange tube is connected to the low-temperature end of the semiconductor thermoelectric power generation module, and the other end is connected to the water storage tank. The circulation pump is installed on the heat exchange tube. The power processing module includes a rectifier, a voltage regulator, and an energy storage unit. The rectifier is electrically connected to the power generation unit of the Stirling power generation module and the semiconductor thermoelectric power generation module, respectively. The voltage regulator is electrically connected to the rectifier. The energy storage unit uses a small lithium battery. The control module includes a temperature sensor, a flow sensor, and a controller. The temperature sensor is located at the connection between the heat exchange chamber and the waste heat inlet pipe, the flow sensor is located on the waste heat inlet pipe, and the controller is electrically connected to the temperature sensor, the flow sensor, the circulating pump, and the power processing module.

2. The Stirling and semiconductor temperature difference composite micro cogeneration device adapted to waste heat from biomass boilers according to claim 1, characterized in that, The waste heat introduction pipe is made of corrosion-resistant stainless steel with a diameter of 50-80mm; the insulation sleeve is made of rock wool insulation layer with a thickness of 10-15mm and an insulation efficiency of ≥90%.

3. The Stirling and semiconductor temperature difference composite micro cogeneration device adapted to waste heat from biomass boilers according to claim 1, characterized in that, The heat storage body is a composite heat storage material made of paraffin and expanded graphite, with a phase change temperature of 80-100℃.

4. A Stirling and semiconductor temperature difference composite micro cogeneration device adapted to waste heat from biomass boilers according to claim 1, characterized in that, Thermally conductive silicone pads are provided between the high-temperature end and the cold-end heat exchanger of the semiconductor thermoelectric power generation module, and between the low-temperature end and the heat exchange tube. The thickness of the thermally conductive silicone pads is 1-2mm, and the thermal conductivity is ≥2.0W / (m·K).

5. A Stirling and semiconductor temperature difference composite micro cogeneration device adapted to waste heat from biomass boilers according to claim 1, characterized in that, The water storage tank is equipped with a temperature monitor and a water inlet, and the temperature monitor is electrically connected to the controller.

6. A Stirling and semiconductor temperature difference composite micro cogeneration device adapted to waste heat from biomass boilers according to claim 1, characterized in that, The control module also includes a wireless communication unit for transmitting device operating parameters to a mobile terminal.

7. A Stirling and semiconductor temperature difference composite micro cogeneration device adapted to waste heat from biomass boilers according to claim 1, characterized in that, The device adopts a modular design, and the modules are connected by flanges.

8. A Stirling and semiconductor temperature difference composite micro cogeneration device adapted to waste heat from biomass boilers according to claim 1, characterized in that, The Stirling power generation module has a power output of 50-100W, and the semiconductor thermoelectric power generation module has a power output of 20-50W.

9. A Stirling and semiconductor temperature difference composite micro cogeneration device adapted to waste heat from biomass boilers according to claim 1, characterized in that, The Stirling power generation module's power generation unit is a piezoelectric ceramic power generation component, which has no mechanical moving parts, operates without wear, and has a service life of no less than 10 years.

10. A Stirling and semiconductor temperature difference composite micro cogeneration device adapted to waste heat from biomass boilers according to claim 1, characterized in that, The overall waste heat utilization rate of the device is no less than 85%, which can simultaneously meet the integrated needs of power generation, heating and hot water supply for residential and small commercial venues.

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